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Ferreira JJ, Kent LN, McCarthy R, Butler A, Ma X, Peramsetty N, Amazu C, Zhang A, Whitter GC, England SK, Santi CM. SLO2.1/NALCN Functional Complex Activity in Mouse Myometrial Smooth Muscle Cells During Pregnancy. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.29.596465. [PMID: 38853884 PMCID: PMC11160795 DOI: 10.1101/2024.05.29.596465] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2024]
Abstract
At the end of pregnancy, the uterus transitions from a quiescent to a highly contractile state. This is partly due to depolarization of the resting membrane potential in uterine (myometrial) smooth muscle cells (MSMCs). Experiments with human MSMCs showed that the membrane potential is regulated by a functional complex between the sodium (Na+)-activated potassium (K+) channel SLO2.1 and the Na+ Leak Channel Non-Selective (NALCN). In human MSMCs, Na+ entering through NALCN activates SLO2.1, leading to K+ efflux, membrane hyperpolarization (cells become more negative inside), and reduced contractility. Decreased SLO2.1/NALCN activity results in reduced K+ efflux, leading to membrane depolarization, Ca2+ influx via voltage-dependent calcium channels, and increased MSMC contractility. However, all of these experiments were performed with MSMCs isolated from women at term, so the role of the SLO2.1/NALCN complex early in pregnancy was speculative. To address this question here, we examined the role of the SLO2.1/NALCN complex in regulating mouse MSMC membrane potential across pregnancy. We report that Slo2.1 and Nalcn expression change along pregnancy, being more highly expressed in MSMCs from non-pregnant and early pregnant mice than in those from late-pregnant mice. Functional studies revealed that SLO2.1 channels mediate a significant portion of the K+ current in mouse MSMCs, particularly in cells from non-pregnant and early pregnant mice. Activation of SLO2.1 by Na+ influx through NALCN led to membrane hyperpolarization in MSMCs from early pregnancy but not in MSMCs from later pregnancy. Moreover, we found that the NALCN/SLO2.1 complex regulates intracellular Ca2+ responses more in MSMCs from non-pregnant and early pregnancy mice than in MSMCs from late pregnancy. Together, these findings reveal that the SLO2.1/NALCN functional complex is conserved between mouse and humans and functions throughout pregnancy. This work could open avenues for targeted pharmacological interventions in pregnancy-related complications.
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Affiliation(s)
| | | | - Ronald McCarthy
- Department of Obstetrics and Gynecology, Center for Reproductive Health Sciences, Washington University in St. Louis, School of Medicine, 425 S. Euclid Avenue, CB 8064, St. Louis, MO 63110, USA
| | - Alice Butler
- Department of Obstetrics and Gynecology, Center for Reproductive Health Sciences, Washington University in St. Louis, School of Medicine, 425 S. Euclid Avenue, CB 8064, St. Louis, MO 63110, USA
| | - Xiaofeng Ma
- Department of Obstetrics and Gynecology, Center for Reproductive Health Sciences, Washington University in St. Louis, School of Medicine, 425 S. Euclid Avenue, CB 8064, St. Louis, MO 63110, USA
| | - Nikita Peramsetty
- Department of Obstetrics and Gynecology, Center for Reproductive Health Sciences, Washington University in St. Louis, School of Medicine, 425 S. Euclid Avenue, CB 8064, St. Louis, MO 63110, USA
| | - Chinwendu Amazu
- Department of Obstetrics and Gynecology, Center for Reproductive Health Sciences, Washington University in St. Louis, School of Medicine, 425 S. Euclid Avenue, CB 8064, St. Louis, MO 63110, USA
| | - Alexander Zhang
- Department of Obstetrics and Gynecology, Center for Reproductive Health Sciences, Washington University in St. Louis, School of Medicine, 425 S. Euclid Avenue, CB 8064, St. Louis, MO 63110, USA
| | - Grace C. Whitter
- Department of Obstetrics and Gynecology, Center for Reproductive Health Sciences, Washington University in St. Louis, School of Medicine, 425 S. Euclid Avenue, CB 8064, St. Louis, MO 63110, USA
| | - Sarah K. England
- Department of Obstetrics and Gynecology, Center for Reproductive Health Sciences, Washington University in St. Louis, School of Medicine, 425 S. Euclid Avenue, CB 8064, St. Louis, MO 63110, USA
| | - Celia M. Santi
- Department of Obstetrics and Gynecology, Center for Reproductive Health Sciences, Washington University in St. Louis, School of Medicine, 425 S. Euclid Avenue, CB 8064, St. Louis, MO 63110, USA
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2
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Ng ACH, Chahine M, Scantlebury MH, Appendino JP. Channelopathies in epilepsy: an overview of clinical presentations, pathogenic mechanisms, and therapeutic insights. J Neurol 2024; 271:3063-3094. [PMID: 38607431 DOI: 10.1007/s00415-024-12352-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2024] [Revised: 03/24/2024] [Accepted: 03/25/2024] [Indexed: 04/13/2024]
Abstract
Pathogenic variants in genes encoding ion channels are causal for various pediatric and adult neurological conditions. In particular, several epilepsy syndromes have been identified to be caused by specific channelopathies. These encompass a spectrum from self-limited epilepsies to developmental and epileptic encephalopathies spanning genetic and acquired causes. Several of these channelopathies have exquisite responses to specific antiseizure medications (ASMs), while others ASMs may prove ineffective or even worsen seizures. Some channelopathies demonstrate phenotypic pleiotropy and can cause other neurological conditions outside of epilepsy. This review aims to provide a comprehensive exploration of the pathophysiology of seizure generation, ion channels implicated in epilepsy, and several genetic epilepsies due to ion channel dysfunction. We outline the clinical presentation, pathogenesis, and the current state of basic science and clinical research for these channelopathies. In addition, we briefly look at potential precision therapy approaches emerging for these disorders.
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Affiliation(s)
- Andy Cheuk-Him Ng
- Clinical Neuroscience and Pediatric Neurology, Department of Pediatrics, Cumming School of Medicine, Alberta Children's Hospital, University of Calgary, 28 Oki Drive NW, Calgary, AB, T3B 6A8, Canada
- Division of Neurology, Department of Pediatrics, Faculty of Medicine and Dentistry, University of Alberta and Stollery Children's Hospital, Edmonton, AB, Canada
| | - Mohamed Chahine
- Department of Medicine, Faculty of Medicine, Université Laval, Quebec City, QC, Canada
- CERVO, Brain Research Centre, Quebec City, Canada
| | - Morris H Scantlebury
- Clinical Neuroscience and Pediatric Neurology, Department of Pediatrics, Cumming School of Medicine, Alberta Children's Hospital, University of Calgary, 28 Oki Drive NW, Calgary, AB, T3B 6A8, Canada
- Hotchkiss Brain Institute and Alberta Children's Hospital Research Institute, Calgary, Canada
| | - Juan P Appendino
- Clinical Neuroscience and Pediatric Neurology, Department of Pediatrics, Cumming School of Medicine, Alberta Children's Hospital, University of Calgary, 28 Oki Drive NW, Calgary, AB, T3B 6A8, Canada.
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3
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Shore AN, Li K, Safari M, Qunies AM, Spitznagel BD, Weaver CD, Emmitte KA, Frankel WN, Weston MC. Heterozygous expression of a Kcnt1 gain-of-function variant has differential effects on SST- and PV-expressing cortical GABAergic neurons. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.10.11.561953. [PMID: 37873369 PMCID: PMC10592778 DOI: 10.1101/2023.10.11.561953] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
More than twenty recurrent missense gain-of-function (GOF) mutations have been identified in the sodium-activated potassium (KNa) channel gene KCNT1 in patients with severe developmental and epileptic encephalopathies (DEEs), most of which are resistant to current therapies. Defining the neuron types most vulnerable to KCNT1 GOF will advance our understanding of disease mechanisms and provide refined targets for precision therapy efforts. Here, we assessed the effects of heterozygous expression of a Kcnt1 GOF variant (Y777H) on KNa currents and neuronal physiology among cortical glutamatergic and GABAergic neurons in mice, including those expressing vasoactive intestinal polypeptide (VIP), somatostatin (SST), and parvalbumin (PV), to identify and model the pathogenic mechanisms of autosomal dominant KCNT1 GOF variants in DEEs. Although the Kcnt1-Y777H variant had no effects on glutamatergic or VIP neuron function, it increased subthreshold KNa currents in both SST and PV neurons but with opposite effects on neuronal output; SST neurons became hypoexcitable with a higher rheobase current and lower action potential (AP) firing frequency, whereas PV neurons became hyperexcitable with a lower rheobase current and higher AP firing frequency. Further neurophysiological and computational modeling experiments showed that the differential effects of the Y777H variant on SST and PV neurons are not likely due to inherent differences in these neuron types, but to an increased persistent sodium current in PV, but not SST, neurons. The Y777H variant also increased excitatory input onto, and chemical and electrical synaptic connectivity between, SST neurons. Together, these data suggest differential pathogenic mechanisms, both direct and compensatory, contribute to disease phenotypes, and provide a salient example of how a pathogenic ion channel variant can cause opposite functional effects in closely related neuron subtypes due to interactions with other ionic conductances.
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Affiliation(s)
- Amy N. Shore
- Fralin Biomedical Research Institute at Virginia Tech Carilion, Center for Neurobiology Research, Roanoke, VA, USA
- Department of Neurological Sciences, University of Vermont, Burlington, VT, USA
| | - Keyong Li
- Fralin Biomedical Research Institute at Virginia Tech Carilion, Center for Neurobiology Research, Roanoke, VA, USA
| | - Mona Safari
- Fralin Biomedical Research Institute at Virginia Tech Carilion, Center for Neurobiology Research, Roanoke, VA, USA
- Translational Biology, Medicine, and Health Graduate Program, Fralin Biomedical Research Institute at Virginia Tech Carilion, Roanoke, VA, USA
| | - Alshaima’a M. Qunies
- Department of Pharmaceutical Sciences, UNT System College of Pharmacy, University of North Texas Health Science Center, Fort Worth, TX, USA
- School of Biomedical Sciences, University of North Texas Health Science Center, Fort Worth, TX, USA
| | - Brittany D. Spitznagel
- Department of Pharmacology, Vanderbilt University, Nashville, TN, USA
- Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, TN, USA
- Department of Chemistry, Vanderbilt University, Nashville, TN, USA
| | - C. David Weaver
- Department of Pharmacology, Vanderbilt University, Nashville, TN, USA
- Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, TN, USA
- Department of Chemistry, Vanderbilt University, Nashville, TN, USA
| | - Kyle A. Emmitte
- Department of Pharmaceutical Sciences, UNT System College of Pharmacy, University of North Texas Health Science Center, Fort Worth, TX, USA
| | - Wayne N. Frankel
- Institute for Genomic Medicine, Columbia University, New York, NY, USA
- Department of Neurology, Columbia University, New York, NY, USA
| | - Matthew C. Weston
- Fralin Biomedical Research Institute at Virginia Tech Carilion, Center for Neurobiology Research, Roanoke, VA, USA
- Department of Neurological Sciences, University of Vermont, Burlington, VT, USA
- Translational Biology, Medicine, and Health Graduate Program, Fralin Biomedical Research Institute at Virginia Tech Carilion, Roanoke, VA, USA
- School of Neuroscience, Virginia Tech, Blacksburg, VA, USA
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Cui F, Wulan T, Zhang Q, Zhang VW, Jiang Y. Identification of a novel KCNT2 variant in a family with developmental and epileptic encephalopathies: a case report and literature review. Front Genet 2024; 15:1371282. [PMID: 38510274 PMCID: PMC10951377 DOI: 10.3389/fgene.2024.1371282] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2024] [Accepted: 02/20/2024] [Indexed: 03/22/2024] Open
Abstract
Background: Developmental and epileptic encephalopathies (DEEs) are a group of heterogeneous neurodevelopmental diseases characterized mainly by developmental delay/intellectual disability and early-onset epilepsy. Researchers have identified variations in the KCNT2 gene (OMIM* 610044) as the cause of DEE type 57 (MIM# 617771). Case presentation: We report in this study a 46-year-old woman who presented with early-onset epilepsy, intellectual disability, hypertrichosis, coarse facial features, and short stature. Besides, there were four other affected individuals in her family history, including two elder brothers, a younger brother, and their mother. We collected blood samples from the proband, her two affected brothers, and her clinically normal daughter for genetic analysis. Clinical exome sequencing revealed a novel heterozygous variant in the KCNT2 gene (NM_198503: c.188G>A, p.Arg63His) in the proband and her two affected brothers, while her daughter did not carry this variant. Furthermore, we reviewed all 25 patients identified in the literature with KCNT2 variants and compared their phenotypes. Conclusion: Epilepsy and intellectual disability/developmental delay occur in almost all patients with KCNT2 variants. KCNT2-relevant DEEs partially overlap with the clinical phenotypes of KATP channel diseases, particularly in hypertrichosis and distinctive coarse facial features.
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Affiliation(s)
- Fengji Cui
- Department of Molecular Genetics, Chifeng Maternity Hospital, Chifeng, China
| | - Tuoya Wulan
- Department of Reproduction, Chifeng Maternity Hospital, Chifeng, China
| | | | | | - Yuhua Jiang
- Department of Obstetrics, Chifeng Maternity Hospital, Chifeng, China
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Malone TJ, Wu J, Zhang Y, Licznerski P, Chen R, Nahiyan S, Pedram M, Jonas EA, Kaczmarek LK. Neuronal potassium channel activity triggers initiation of mRNA translation through binding of translation regulators. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.07.579306. [PMID: 38370631 PMCID: PMC10871293 DOI: 10.1101/2024.02.07.579306] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/20/2024]
Abstract
Neuronal activity stimulates mRNA translation crucial for learning and development. While FMRP (Fragile X Mental Retardation Protein) and CYFIP1 (Cytoplasmic FMR1 Interacting Protein 1) regulate translation, the mechanism linking translation to neuronal activity is not understood. We now find that translation is stimulated when FMRP and CYFIP1 translocate to the potassium channel Slack (KCNT1, Slo2.2). When Slack is activated, both factors are released from eIF4E (Eukaryotic Initiation Factor 4E), where they normally inhibit translation initiation. A constitutively active Slack mutation and pharmacological stimulation of the wild-type channel both increase binding of FMRP and CYFIP1 to the channel, enhancing the translation of a reporter for β-actin mRNA in cell lines and the synthesis of β-actin in neuronal dendrites. Slack activity-dependent translation is abolished when both FMRP and CYFIP1 expression are suppressed. The effects of Slack mutations on activity-dependent translation may explain the severe intellectual disability produced by these mutations in humans. HIGHLIGHTS Activation of Slack channels triggers translocation of the FMRP/CYFIP1 complexSlack channel activation regulates translation initiation of a β-actin reporter constructA Slack gain-of-function mutation increases translation of β-actin reporter construct and endogenous cortical β-actinFMRP and CYFIP1 are required for Slack activity-dependent translation. IN BRIEF Malone et al . show that the activation of Slack channels triggers translocation of the FMRP/CYFIP1 complex from the translation initiation factor eIF4E to the channel. This translocation releases eIF4E and stimulates mRNA translation of a reporter for β-actin and cortical β-actin mRNA, elucidating the mechanism that connects neuronal activity with translational regulation.
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Qunies AM, Spitznagel BD, Du Y, David Weaver C, Emmitte KA. Design, synthesis, and biological evaluation of a novel series of 1,2,4-oxadiazole inhibitors of SLACK potassium channels: Identification of in vitro tool VU0935685. Bioorg Med Chem 2023; 95:117487. [PMID: 37812884 PMCID: PMC10842602 DOI: 10.1016/j.bmc.2023.117487] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Revised: 09/28/2023] [Accepted: 09/29/2023] [Indexed: 10/11/2023]
Abstract
Malignant migrating partial seizure of infancy (MMPSI) is a devastating and pharmacoresistant form of infantile epilepsy. MMPSI has been linked to multiple gain-of-function (GOF) mutations in the KCNT1 gene, which encodes for a potassium channel often referred to as SLACK. SLACK channels are sodium-activated potassium channels distributed throughout the central nervous system (CNS) and the periphery. The investigation described here aims to discover SLACK channel inhibitor tool compounds and profile their pharmacokinetic and pharmacodynamic properties. A SLACK channel inhibitor VU0531245 (VU245) was identified via a high-throughput screen (HTS) campaign. Structure-activity relationship (SAR) studies were conducted in five distinct regions of the hit VU245. VU245 analogs were evaluated for their ability to affect SLACK channel activity using a thallium flux assay in HEK-293 cells stably expressing wild-type (WT) human SLACK. Selected analogs were tested for metabolic stability in mouse liver microsomes and plasma-protein binding in mouse plasma. The same set of analogs was tested via thallium flux for activity versus human A934T SLACK and other structurally related potassium channels, including SLICK and Maxi-K. In addition, potencies for selected VU245 analogs were obtained using whole-cell electrophysiology (EP) assays in CHO cells stably expressing WT human SLACK through an automated patch clamp system. Results revealed that this scaffold tolerates structural changes in some regions, with some analogs demonstrating improved SLACK inhibitory activity, good selectivity against the other channels tested, and modest improvements in metabolic clearance. Analog VU0935685 represents a new, structurally distinct small-molecule inhibitor of SLACK channels that can serve as an in vitro tool for studying this target.
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Affiliation(s)
- Alshaima'a M Qunies
- Department of Pharmaceutical Sciences, UNT System College of Pharmacy, University of North Texas Health Science Center, Fort Worth, TX 76107, USA; School of Biomedical Sciences, University of North Texas Health Science Center, Fort Worth, TX 76107, USA
| | | | - Yu Du
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA; Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, TN 37232, USA
| | - C David Weaver
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA; Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, TN 37232, USA
| | - Kyle A Emmitte
- Department of Pharmaceutical Sciences, UNT System College of Pharmacy, University of North Texas Health Science Center, Fort Worth, TX 76107, USA.
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7
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Cioclu MC, Mosca I, Ambrosino P, Puzo D, Bayat A, Wortmann SB, Koch J, Strehlow V, Shirai K, Matsumoto N, Sanders SJ, Michaud V, Legendre M, Riva A, Striano P, Muhle H, Pendziwiat M, Lesca G, Mangano GD, Nardello R, Lemke JR, Møller RS, Soldovieri MV, Rubboli G, Taglialatela M. KCNT2-Related Disorders: Phenotypes, Functional, and Pharmacological Properties. Ann Neurol 2023; 94:332-349. [PMID: 37062836 DOI: 10.1002/ana.26662] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 04/10/2023] [Accepted: 04/14/2023] [Indexed: 04/18/2023]
Abstract
OBJECTIVE Pathogenic variants in KCNT2 are rare causes of developmental epileptic encephalopathy (DEE). We herein describe the phenotypic and genetic features of patients with KCNT2-related DEE, and the in vitro functional and pharmacological properties of KCNT2 channels carrying 14 novel or previously untested variants. METHODS Twenty-five patients harboring KCNT2 variants were investigated: 12 were identified through an international collaborative network, 13 were retrieved from the literature. Clinical data were collected and included in a standardized phenotyping sheet. Novel variants were detected using exome sequencing and classified using ACMG criteria. Functional and pharmacological studies were performed by whole-cell electrophysiology in HEK-293 and SH-SY5Y cells. RESULTS The phenotypic spectrum encompassed: (a) intellectual disability/developmental delay (21/22 individuals with available information), ranging from mild to severe/profound; (b) epilepsy (15/25); (c) neurological impairment, with altered muscle tone (14/22); (d) dysmorphisms (13/20). Nineteen pathogenic KCNT2 variants were found (9 new, 10 reported previously): 16 missense, 1 in-frame deletion of a single amino acid, 1 nonsense, and 1 frameshift. Among tested variants, 8 showed gain-of-function (GoF), and 6 loss-of-function (LoF) features when expressed heterologously in vitro. Quinidine and fluoxetine blocked all GoF variants, whereas loxapine and riluzole activated some LoF variants while blocking others. INTERPRETATION We expanded the phenotypic and genotypic spectrum of KCNT2-related disorders, highlighting novel genotype-phenotype associations. Pathogenic KCNT2 variants cause GoF or LoF in vitro phenotypes, and each shows a unique pharmacological profile, suggesting the need for in vitro functional and pharmacological investigation to enable targeted therapies based on the molecular phenotype. ANN NEUROL 2023;94:332-349.
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Affiliation(s)
- Maria Cristina Cioclu
- Department of Epilepsy Genetics and Personalized Medicine (member of ERN EpiCARE), Danish Epilepsy Centre, Dianalund, Denmark
- Department of Biomedical, Metabolic, and Neural Science, University of Modena and Reggio Emilia, Modena, Italy
| | - Ilaria Mosca
- Department of Medicine and Health Sciences "Vincenzo Tiberio", University of Molise, Campobasso, Italy
| | - Paolo Ambrosino
- Dept. of Science and Technology, University of Sannio, Benevento, Italy
| | - Deborah Puzo
- Department of Medicine and Health Sciences "Vincenzo Tiberio", University of Molise, Campobasso, Italy
| | - Allan Bayat
- Department of Epilepsy Genetics and Personalized Medicine (member of ERN EpiCARE), Danish Epilepsy Centre, Dianalund, Denmark
- Department of Regional Health Research, University of Southern Denmark, Odense, Denmark
| | - Saskia B Wortmann
- University Children's Hospital, Paracelsus Medical University, Salzburg, Austria
- Amalia Children's Hospital, Nijmegen, The Netherlands
| | - Johannes Koch
- University Children's Hospital, Paracelsus Medical University, Salzburg, Austria
| | - Vincent Strehlow
- Institute of Human Genetics, University of Leipzig Medical Center, Leipzig, Germany
| | - Kentaro Shirai
- Department of Pediatrics, Tsuchiura Kyodo General Hospital, Tsuchiura, Japan
| | - Naomichi Matsumoto
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Stephan J Sanders
- Department of Psychiatry and Behavioral Sciences, UCSF Weill Institute for Neurosciences, University of California, San Francisco, CA, USA
- Institute for Human Genetics, University of California, San Francisco, CA, USA
- Bakar Computational Health Sciences Institute, University of California, San Francisco, CA, USA
| | - Vincent Michaud
- Service de Génétique Médicale, Centre de Référence Anomalies du Développement et Syndrome Malformatifs, Centre Hospitalier Universitaire de Bordeaux, Bordeaux, France
- Maladies rares: Génétique et Métabolisme (MRGM), INSERM U1211, Université de Bordeaux, Bordeaux, France
| | - Marine Legendre
- Service de Génétique Médicale, Centre de Référence Anomalies du Développement et Syndrome Malformatifs, Centre Hospitalier Universitaire de Bordeaux, Bordeaux, France
| | - Antonella Riva
- IRCCS Istituto Giannina Gaslini, Genoa, Italy
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, Genoa, Italy
| | - Pasquale Striano
- IRCCS Istituto Giannina Gaslini, Genoa, Italy
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, Genoa, Italy
| | - Hiltrud Muhle
- Department of Neuropediatrics, University Medical Centre Schleswig-Holstein, Christian-Albrechts-University, Kiel, Germany
| | - Manuela Pendziwiat
- Department of Neuropediatrics, University Medical Centre Schleswig-Holstein, Christian-Albrechts-University, Kiel, Germany
- Institute of Clinical Molecular Biology, Christian-Albrechts-University of Kiel, Kiel, Germany
| | - Gaetan Lesca
- Pathophysiology and Genetics of Neuron and Muscle (PNMG), UCBL, CNRS UMR5261-INSERM U1315, Lyon, France
- Department of Medical Genetics, University Hospital of Lyon and Claude Bernard Lyon I University, Lyon, France
| | - Giuseppe Donato Mangano
- Department of Biomedicine, Neuroscience and Advanced Diagnostics, University of Palermo, Palermo, Italy
| | - Rosaria Nardello
- Department of Health Promotion, Mother and Child Care, Internal Medicine and Medical Specialties "G. D'Alessandro", University of Palermo, Palermo, Italy
| | - Johannes R Lemke
- Institute of Human Genetics, University of Leipzig Medical Center, Leipzig, Germany
- Center for Rare Diseases, University of Leipzig Medical Center, Leipzig, Germany
| | - Rikke S Møller
- Department of Epilepsy Genetics and Personalized Medicine (member of ERN EpiCARE), Danish Epilepsy Centre, Dianalund, Denmark
- Department of Regional Health Research, University of Southern Denmark, Odense, Denmark
| | - Maria Virginia Soldovieri
- Department of Medicine and Health Sciences "Vincenzo Tiberio", University of Molise, Campobasso, Italy
| | - Guido Rubboli
- Department of Epilepsy Genetics and Personalized Medicine (member of ERN EpiCARE), Danish Epilepsy Centre, Dianalund, Denmark
- University of Copenhagen, Copenhagen, Denmark
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Liu R, Sun L, Wang Y, Jia M, Wang Q, Cai X, Wu J. Double-edged Role of K Na Channels in Brain Tuning: Identifying Epileptogenic Network Micro-Macro Disconnection. Curr Neuropharmacol 2022; 20:916-928. [PMID: 34911427 PMCID: PMC9881102 DOI: 10.2174/1570159x19666211215104829] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Revised: 11/09/2021] [Accepted: 12/10/2021] [Indexed: 11/22/2022] Open
Abstract
Epilepsy is commonly recognized as a disease driven by generalized hyperexcited and hypersynchronous neural activity. Sodium-activated potassium channels (KNa channels), which are encoded by the Slo 2.2 and Slo 2.1 genes, are widely expressed in the central nervous system and considered as "brakes" to adjust neuronal adaptation through regulating action potential threshold or after-hyperpolarization under physiological condition. However, the variants in KNa channels, especially gain-of-function variants, have been found in several childhood epileptic conditions. Most previous studies focused on mapping the epileptic network on the macroscopic scale while ignoring the value of microscopic changes. Notably, paradoxical role of KNa channels working on individual neuron/microcircuit and the macroscopic epileptic expression highlights the importance of understanding epileptogenic network through combining microscopic and macroscopic methods. Here, we first illustrated the molecular and physiological function of KNa channels on preclinical seizure models and patients with epilepsy. Next, we summarized current hypothesis on the potential role of KNa channels during seizures to provide essential insight into what emerged as a micro-macro disconnection at different levels. Additionally, we highlighted the potential utility of KNa channels as therapeutic targets for developing innovative anti-seizure medications.
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Affiliation(s)
- Ru Liu
- Beijing Tiantan Hospital, Capital Medical University, Beijing, China;,Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, China;,China National Clinical Research Center for Neurological Diseases, Beijing, China
| | - Lei Sun
- Beijing Tiantan Hospital, Capital Medical University, Beijing, China;,Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, China;,China National Clinical Research Center for Neurological Diseases, Beijing, China
| | | | - Meng Jia
- Beijing Tiantan Hospital, Capital Medical University, Beijing, China;,Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, China;,China National Clinical Research Center for Neurological Diseases, Beijing, China
| | - Qun Wang
- Beijing Tiantan Hospital, Capital Medical University, Beijing, China;,China National Clinical Research Center for Neurological Diseases, Beijing, China
| | - Xiang Cai
- Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, China;,Address correspondence to these authors at the Beijing Tiantan Hospital, Capital Medical University, Beijing, China; Tel: +0086-18062552085; E-mail: Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, China; Tel: +0086-13319285082; E-mail:
| | - Jianping Wu
- Beijing Tiantan Hospital, Capital Medical University, Beijing, China;,Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, China;,China National Clinical Research Center for Neurological Diseases, Beijing, China;,Address correspondence to these authors at the Beijing Tiantan Hospital, Capital Medical University, Beijing, China; Tel: +0086-18062552085; E-mail: Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, China; Tel: +0086-13319285082; E-mail:
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9
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Slick Potassium Channels Control Pain and Itch in Distinct Populations of Sensory and Spinal Neurons in Mice. Anesthesiology 2022; 136:802-822. [PMID: 35303056 DOI: 10.1097/aln.0000000000004163] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Slick, a sodium-activated potassium channel, has been recently identified in somatosensory pathways, but its functional role is poorly understood. The authors of this study hypothesized that Slick is involved in processing sensations of pain and itch. METHODS Immunostaining, in situ hybridization, Western blot, and real-time quantitative reverse transcription polymerase chain reaction were used to investigate the expression of Slick in dorsal root ganglia and the spinal cord. Mice lacking Slick globally (Slick-/-) or conditionally in neurons of the spinal dorsal horn (Lbx1-Slick-/-) were assessed in behavioral models. RESULTS The authors found Slick to be enriched in nociceptive Aδ-fibers and in populations of interneurons in the spinal dorsal horn. Slick-/- mice, but not Lbx1-Slick-/- mice, showed enhanced responses to noxious heat in the hot plate and tail-immersion tests. Both Slick-/- and Lbx1-Slick-/- mice demonstrated prolonged paw licking after capsaicin injection (mean ± SD, 45.6 ± 30.1 s [95% CI, 19.8 to 71.4]; and 13.1 ± 16.1 s [95% CI, 1.8 to 28.0]; P = 0.006 [Slick-/- {n = 8} and wild-type {n = 7}, respectively]), which was paralleled by increased phosphorylation of the neuronal activity marker extracellular signal-regulated kinase in the spinal cord. In the spinal dorsal horn, Slick is colocalized with somatostatin receptor 2 (SSTR2), and intrathecal preadministration of the SSTR2 antagonist CYN-154806 prevented increased capsaicin-induced licking in Slick-/- and Lbx1-Slick-/- mice. Moreover, scratching after intrathecal delivery of the somatostatin analog octreotide was considerably reduced in Slick-/- and Lbx1-Slick-/- mice (Slick-/- [n = 8]: 6.1 ± 6.7 bouts [95% CI, 0.6 to 11.7]; wild-type [n =8]: 47.4 ± 51.1 bouts [95% CI, 4.8 to 90.2]; P = 0.039). CONCLUSIONS Slick expressed in a subset of sensory neurons modulates heat-induced pain, while Slick expressed in spinal cord interneurons inhibits capsaicin-induced pain but facilitates somatostatin-induced itch. EDITOR’S PERSPECTIVE
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10
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Gao L, Zhao J, Ardiel EL, Hall Q, Nurrish S, Kaplan JM. Shank promotes action potential repolarization by recruiting BK channels to calcium microdomains. eLife 2022; 11:75140. [PMID: 35266450 PMCID: PMC8937234 DOI: 10.7554/elife.75140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2021] [Accepted: 03/09/2022] [Indexed: 11/13/2022] Open
Abstract
Mutations altering the scaffolding protein Shank are linked to several psychiatric disorders, and to synaptic and behavioral defects in mice. Among its many binding partners, Shank directly binds CaV1 voltage activated calcium channels. Here we show that the C. elegans SHN-1/Shank promotes CaV1 coupling to calcium activated potassium channels. Mutations inactivating SHN-1, and those preventing SHN-1 binding to EGL-19/CaV1 all increase action potential durations in body muscles. Action potential repolarization is mediated by two classes of potassium channels: SHK-1/KCNA and SLO-1 and SLO-2 BK channels. BK channels are calcium-dependent, and their activation requires tight coupling to EGL-19/CaV1 channels. SHN-1's effects on AP duration are mediated by changes in BK channels. In shn-1 mutants, SLO-2 currents and channel clustering are significantly decreased in both body muscles and neurons. Finally, increased and decreased shn-1 gene copy number produce similar changes in AP width and SLO-2 current. Collectively, these results suggest that an important function of Shank is to promote microdomain coupling of BK with CaV1.
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Affiliation(s)
- Luna Gao
- Department of Molecular Biology, Massachusetts General Hospital, Boston, United States
| | - Jian Zhao
- Department of Molecular Biology, Massachusetts General Hospital, Boston, United States
| | - Evan L Ardiel
- Department of Molecular Biology, Massachusetts General Hospital, Boston, United States
| | - Qi Hall
- Department of Molecular Biology, Massachusetts General Hospital, Boston, United States
| | - Stephen Nurrish
- Department of Molecular Biology, Massachusetts General Hospital, Boston, United States
| | - Joshua M Kaplan
- Department of Molecular Biology, Massachusetts General Hospital, Boston, United States
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11
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Zhang Q, Liu Y, Xu J, Teng Y, Zhang Z. The Functional Properties, Physiological Roles, Channelopathy and Pharmacological Characteristics of the Slack (KCNT1) Channel. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2022; 1349:387-400. [PMID: 35138624 DOI: 10.1007/978-981-16-4254-8_18] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The KCNT1 gene encodes the sodium-activated potassium channel that is abundantly expressed in the central nervous system of mammalians and plays an important role in reducing neuronal excitability. Structurally, the KCNT1 channel is absent of voltage sensor but possesses a long C-terminus including RCK1 and RCK2domain, to which the intracellular sodium and chloride bind to activate the channel. Recent publications using electron cryo-microscopy (cryo-EM) revealed the open and closed structural characteristics of the KCNT1 channel and co-assembly of functional domains. The activation of the KCNT1 channel regulates various physiological processes including nociceptive behavior, itch, spatial learning. Meanwhile, malfunction of this channel causes important pathophysiological consequences, including Fragile X syndrome and a wide spectrum of seizure disorders. This review comprehensively describes the structure, expression patterns, physiological functions of the KCNT1 channel and emphasizes the channelopathy of gain-of-function KCNT1 mutations in epilepsy.
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Affiliation(s)
- Qi Zhang
- Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical University, Xuzhou, Jiangsu Province, China
- Jiangsu Province Key Laboratory of Anesthesia and Analgesia Application Technology, Xuzhou Medical University, Xuzhou, Jiangsu Province, China
| | - Ye Liu
- Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical University, Xuzhou, Jiangsu Province, China
- Jiangsu Province Key Laboratory of Anesthesia and Analgesia Application Technology, Xuzhou Medical University, Xuzhou, Jiangsu Province, China
| | - Jie Xu
- Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical University, Xuzhou, Jiangsu Province, China
- Jiangsu Province Key Laboratory of Anesthesia and Analgesia Application Technology, Xuzhou Medical University, Xuzhou, Jiangsu Province, China
| | - Yue Teng
- Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical University, Xuzhou, Jiangsu Province, China
- Jiangsu Province Key Laboratory of Anesthesia and Analgesia Application Technology, Xuzhou Medical University, Xuzhou, Jiangsu Province, China
| | - Zhe Zhang
- Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical University, Xuzhou, Jiangsu Province, China.
- Jiangsu Province Key Laboratory of Anesthesia and Analgesia Application Technology, Xuzhou Medical University, Xuzhou, Jiangsu Province, China.
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12
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Ehinger R, Kuret A, Matt L, Frank N, Wild K, Kabagema-Bilan C, Bischof H, Malli R, Ruth P, Bausch AE, Lukowski R. Slack K + channels attenuate NMDA-induced excitotoxic brain damage and neuronal cell death. FASEB J 2021; 35:e21568. [PMID: 33817875 DOI: 10.1096/fj.202002308rr] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Revised: 03/14/2021] [Accepted: 03/17/2021] [Indexed: 12/13/2022]
Abstract
The neuronal Na+ -activated K+ channel Slack (aka Slo2.2, KNa 1.1, or Kcnt1) has been implicated in setting and maintaining the resting membrane potential and defining excitability and firing patterns, as well as in the generation of the slow afterhyperpolarization following bursts of action potentials. Slack activity increases significantly under conditions of high intracellular Na+ levels, suggesting this channel may exert important pathophysiological functions. To address these putative roles, we studied whether Slack K+ channels contribute to pathological changes and excitotoxic cell death caused by glutamatergic overstimulation of Ca2+ - and Na+ -permeable N-methyl-D-aspartic acid receptors (NMDAR). Slack-deficient (Slack KO) and wild-type (WT) mice were subjected to intrastriatal microinjections of the NMDAR agonist NMDA. NMDA-induced brain lesions were significantly increased in Slack KO vs WT mice, suggesting that the lack of Slack renders neurons particularly susceptible to excitotoxicity. Accordingly, excessive neuronal cell death was seen in Slack-deficient primary cerebellar granule cell (CGC) cultures exposed to glutamate and NMDA. Differences in neuronal survival between WT and Slack KO CGCs were largely abolished by the NMDAR antagonist MK-801, but not by NBQX, a potent and highly selective competitive antagonist of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-type ionotropic glutamate receptors. Interestingly, NMDAR-evoked Ca2+ signals did not differ with regard to Slack genotype in CGCs. However, real-time monitoring of K+ following NMDAR activation revealed a significant contribution of this channel to the intracellular drop in K+ . Finally, TrkB and TrkC neurotrophin receptor transcript levels were elevated in NMDA-exposed Slack-proficient CGCs, suggesting a mechanism by which this K+ channel contributes to the activation of the extracellular-signal-regulated kinase (Erk) pathway and thereby to neuroprotection. Combined, our findings suggest that Slack-dependent K+ signals oppose the NMDAR-mediated excitotoxic neuronal injury by promoting pro-survival signaling via the BDNF/TrkB and Erk axis.
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Affiliation(s)
- Rebekka Ehinger
- Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, University of Tübingen, Tübingen, Germany
| | - Anna Kuret
- Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, University of Tübingen, Tübingen, Germany
| | - Lucas Matt
- Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, University of Tübingen, Tübingen, Germany
| | - Nadine Frank
- Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, University of Tübingen, Tübingen, Germany
| | - Katharina Wild
- Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, University of Tübingen, Tübingen, Germany
| | - Clement Kabagema-Bilan
- Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, University of Tübingen, Tübingen, Germany
| | - Helmut Bischof
- Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, University of Tübingen, Tübingen, Germany
| | - Roland Malli
- Gottfried Schatz Research Center, Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria
| | - Peter Ruth
- Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, University of Tübingen, Tübingen, Germany
| | - Anne E Bausch
- Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, University of Tübingen, Tübingen, Germany
| | - Robert Lukowski
- Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, University of Tübingen, Tübingen, Germany
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13
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Jackson A, Banka S, Stewart H, Robinson H, Lovell S, Clayton-Smith J. Recurrent KCNT2 missense variants affecting p.Arg190 result in a recognizable phenotype. Am J Med Genet A 2021; 185:3083-3091. [PMID: 34061450 DOI: 10.1002/ajmg.a.62370] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Revised: 03/29/2021] [Accepted: 05/05/2021] [Indexed: 12/13/2022]
Abstract
KCNT2 variants resulting in substitutions affecting the Arg190 residue have been shown to cause epileptic encephalopathy and a recognizable facial gestalt. We report two additional individuals with intellectual disability, dysmorphic features, hypertrichosis, macrocephaly and the same de novo KCNT2 missense variants affecting the Arg190 residue as previously described. Notably, neither patient has epilepsy. Homology modeling of these missense variants revealed that they are likely to disrupt the stabilization of a closed channel conformation of KCNT2 resulting in a constitutively open state. This is the first report of pathogenic variants in KCNT2 causing a developmental phenotype without epilepsy.
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Affiliation(s)
- Adam Jackson
- Manchester Centre for Genomic Medicine, Division of Evolution and Genomic Sciences, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
| | - Siddharth Banka
- Manchester Centre for Genomic Medicine, Division of Evolution and Genomic Sciences, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK.,Manchester Centre for Genomic Medicine, St Mary's Hospital, Manchester University NHS Foundation Trust, Health Innovation Manchester, Manchester, UK
| | - Helen Stewart
- Department of Clinical Genetics, Oxford Centre for Genomic Medicine, Oxford Radcliffe Hospitals NHS Trust, Nuffield Orthopaedic Hospital, Oxford, UK
| | -
- Genomics England, London, UK
| | - Hannah Robinson
- Department of Peninsula Clinical Genetics, Exeter Genomics Laboratory, Royal Devon and Exeter NHS Foundation Trust, Exeter, UK
| | - Simon Lovell
- Division of Evolution and Genomic Sciences, School of Biological Sciences, University of Manchester, Manchester, UK
| | - Jill Clayton-Smith
- Manchester Centre for Genomic Medicine, Division of Evolution and Genomic Sciences, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK.,Manchester Centre for Genomic Medicine, St Mary's Hospital, Manchester University NHS Foundation Trust, Health Innovation Manchester, Manchester, UK
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14
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Cole BA, Clapcote SJ, Muench SP, Lippiat JD. Targeting K Na1.1 channels in KCNT1-associated epilepsy. Trends Pharmacol Sci 2021; 42:700-713. [PMID: 34074526 DOI: 10.1016/j.tips.2021.05.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Revised: 04/30/2021] [Accepted: 05/05/2021] [Indexed: 12/19/2022]
Abstract
Gain-of-function (GOF) pathogenic variants of KCNT1, the gene encoding the largest known potassium channel subunit, KNa1.1, are associated with developmental and epileptic encephalopathies accompanied by severe psychomotor and intellectual disabilities. Blocking hyperexcitable KNa1.1 channels with quinidine, a class I antiarrhythmic drug, has shown variable success in patients in part because of dose-limiting off-target effects, poor blood-brain barrier (BBB) penetration, and low potency. In recent years, high-resolution cryogenic electron microscopy (cryo-EM) structures of the chicken KNa1.1 channel in different activation states have been determined, and animal models of the diseases have been generated. Alongside increasing information about the functional effects of GOF pathogenic variants on KNa1.1 channel behaviour and how they lead to hyperexcitability, these tools will facilitate the development of more effective treatment strategies. We review the range of KCNT1 variants and their functional effects, the challenges posed by current treatment strategies, and recent advances in finding more potent and selective therapeutic interventions for KCNT1-related epilepsies.
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Affiliation(s)
- Bethan A Cole
- School of Biomedical Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Steven J Clapcote
- School of Biomedical Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Stephen P Muench
- School of Biomedical Sciences, University of Leeds, Leeds LS2 9JT, UK
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15
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Venti V, Ciccia L, Scalia B, Sciuto L, Cimino C, Marino S, Praticò AD, Falsaperla R. KCNT1-Related Epilepsy: A Review. JOURNAL OF PEDIATRIC NEUROLOGY 2021. [DOI: 10.1055/s-0041-1728688] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Abstract
KCNT1 gene encodes the sodium-dependent potassium channel reported as a causal factor for several different epileptic disorders. The gene has been also linked with cardiac disorders and in a family to sudden unexpected death in epilepsy. KCNT1 mutations, in most cases, result in a gain of function causing a neuronal hyperpolarization with loss of inhibition. Many early-onset epileptic encephalopathies related to gain of function of KCNT1 gene have been described, most often associated with two phenotypes: malignant migrating focal seizures of infancy and familial autosomal-dominant nocturnal frontal lobe epilepsy; however, there is no clear phenotype–genotype correlation, in fact same mutations have been represented in patients with West syndrome, Ohtahara syndrome, and early myoclonic encephalopathy. Additional neurologic features include intellectual disability, psychiatric disorders, hypotonia, microcephaly, strabismus, and movement disorders. Conventional anticonvulsant, vagal stimulation, and ketogenic diet have been used in the absence of clinical benefit in individuals with KCNT1-related epilepsy; in some patients, quinidine therapy off-label has been practiced successfully. This review aims to describe the characteristics of the gene, the phenotypes related to genetic mutations with the possible genotype–phenotype correlations and the treatments proposed to date, discussing the comorbidities reported in the literature.
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Affiliation(s)
- Valeria Venti
- Pediatrics Postgraduate Residency Program, Section of Pediatrics and Child Neuropsychiatry, Department of Clinical and Experimental Medicine, University of Catania, Catania, Italy
| | - Lina Ciccia
- Pediatrics Postgraduate Residency Program, Section of Pediatrics and Child Neuropsychiatry, Department of Clinical and Experimental Medicine, University of Catania, Catania, Italy
| | - Bruna Scalia
- Pediatrics Postgraduate Residency Program, Section of Pediatrics and Child Neuropsychiatry, Department of Clinical and Experimental Medicine, University of Catania, Catania, Italy
| | - Laura Sciuto
- Pediatrics Postgraduate Residency Program, Section of Pediatrics and Child Neuropsychiatry, Department of Clinical and Experimental Medicine, University of Catania, Catania, Italy
| | - Carla Cimino
- Unit of Pediatrics and Pediatric Emergency, University Hospital “Policlinico Rodolico-San Marco,” Catania, Italy
| | - Simona Marino
- Unit of Neonatal Intensive Care and Neonatology, University Hospital “Policlinico Rodolico-San Marco,” Catania, Italy
| | - Andrea D. Praticò
- Unit of Rare Diseases of the Nervous System in Childhood, Section of Pediatrics and Child Neuropsychiatry, Department of Clinical and Experimental Medicine, University of Catania, Catania, Italy
| | - Raffaele Falsaperla
- Unit of Pediatrics and Pediatric Emergency, University Hospital “Policlinico Rodolico-San Marco,” Catania, Italy
- Unit of Neonatal Intensive Care and Neonatology, University Hospital “Policlinico Rodolico-San Marco,” Catania, Italy
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16
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Shore AN, Colombo S, Tobin WF, Petri S, Cullen ER, Dominguez S, Bostick CD, Beaumont MA, Williams D, Khodagholy D, Yang M, Lutz CM, Peng Y, Gelinas JN, Goldstein DB, Boland MJ, Frankel WN, Weston MC. Reduced GABAergic Neuron Excitability, Altered Synaptic Connectivity, and Seizures in a KCNT1 Gain-of-Function Mouse Model of Childhood Epilepsy. Cell Rep 2020; 33:108303. [PMID: 33113364 PMCID: PMC7712469 DOI: 10.1016/j.celrep.2020.108303] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Revised: 08/06/2020] [Accepted: 10/01/2020] [Indexed: 01/07/2023] Open
Abstract
Gain-of-function (GOF) variants in K+ channels cause severe childhood epilepsies, but there are no mechanisms to explain how increased K+ currents lead to network hyperexcitability. Here, we introduce a human Na+-activated K+ (KNa) channel variant (KCNT1-Y796H) into mice and, using a multiplatform approach, find motor cortex hyperexcitability and early-onset seizures, phenotypes strikingly similar to those of human patients. Although the variant increases KNa currents in cortical excitatory and inhibitory neurons, there is an increase in the KNa current across subthreshold voltages only in inhibitory neurons, particularly in those with non-fast-spiking properties, resulting in inhibitory-neuron-specific impairments in excitability and action potential (AP) generation. We further observe evidence of synaptic rewiring, including increases in homotypic synaptic connectivity, accompanied by network hyperexcitability and hypersynchronicity. These findings support inhibitory-neuron-specific mechanisms in mediating the epileptogenic effects of KCNT1 channel GOF, offering cell-type-specific currents and effects as promising targets for therapeutic intervention.
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Affiliation(s)
- Amy N Shore
- Department of Neurological Sciences, University of Vermont, Burlington, VT 05405, USA
| | - Sophie Colombo
- Institute for Genomic Medicine, Columbia University, New York, NY 10032, USA
| | - William F Tobin
- Department of Neurological Sciences, University of Vermont, Burlington, VT 05405, USA
| | - Sabrina Petri
- Institute for Genomic Medicine, Columbia University, New York, NY 10032, USA
| | - Erin R Cullen
- Department of Neurological Sciences, University of Vermont, Burlington, VT 05405, USA
| | - Soledad Dominguez
- Institute for Genomic Medicine, Columbia University, New York, NY 10032, USA
| | | | - Michael A Beaumont
- Institute for Genomic Medicine, Columbia University, New York, NY 10032, USA; Axion BioSystems, Atlanta, GA 30309, USA
| | - Damian Williams
- Institute for Genomic Medicine, Columbia University, New York, NY 10032, USA
| | - Dion Khodagholy
- Department of Electrical Engineering, Columbia University, New York, NY 10032, USA
| | - Mu Yang
- Institute for Genomic Medicine, Columbia University, New York, NY 10032, USA
| | | | - Yueqing Peng
- Institute for Genomic Medicine, Columbia University, New York, NY 10032, USA; Department of Pathology and Cell Biology, Columbia University, New York, NY 10032, USA
| | - Jennifer N Gelinas
- Institute for Genomic Medicine, Columbia University, New York, NY 10032, USA; Department of Neurology, Columbia University, New York, NY 10032, USA
| | - David B Goldstein
- Institute for Genomic Medicine, Columbia University, New York, NY 10032, USA; Department of Genetics and Development, Columbia University, New York, NY 10032, USA
| | - Michael J Boland
- Institute for Genomic Medicine, Columbia University, New York, NY 10032, USA; Department of Genetics and Development, Columbia University, New York, NY 10032, USA
| | - Wayne N Frankel
- Institute for Genomic Medicine, Columbia University, New York, NY 10032, USA; Department of Neurology, Columbia University, New York, NY 10032, USA
| | - Matthew C Weston
- Department of Neurological Sciences, University of Vermont, Burlington, VT 05405, USA.
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17
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Inuzuka LM, Macedo-Souza LI, Della-Ripa B, Monteiro FP, Ramos L, Kitajima JP, Garzon E, Kok F. Additional observation of a de novo pathogenic variant in KCNT2 leading to epileptic encephalopathy with clinical features of frontal lobe epilepsy. Brain Dev 2020; 42:691-695. [PMID: 32773162 DOI: 10.1016/j.braindev.2020.05.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 05/07/2020] [Accepted: 05/08/2020] [Indexed: 12/16/2022]
Abstract
INTRODUCTION KCNT2 was recently recognized as a gene associated with neurodevelopmental disorder and epilepsy. CASE REPORT We present an additional observation of a 16-year-old male patient with a novel de novo KCNT2 likely pathogenic variant and review the five previously reported cases of de novo variants in this gene. DISCUSSION Whole exome sequencing identified the missense variant c.725C > A p.(Thr242Asn), which was confirmed by Sanger sequencing. Our patient has a refractory stereotyped and monomorphic type of hyperkinetic focal motor seizure, similar to what is seen in frontal lobe epilepsy, occurring only during sleep. This type of seizure is not usually seen in epileptic encephalopathies.
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Affiliation(s)
- Luciana Midori Inuzuka
- Epilepsy Clinic, Hospital Sírio-Libanês, São Paulo, Brazil; Department of Neurology, University of São Paulo School of Medicine, Brazil.
| | | | - Bruno Della-Ripa
- Department of Neurology, University of São Paulo School of Medicine, Brazil
| | | | - Luiza Ramos
- Mendelics Genomic Analysis, São Paulo, Brazil
| | | | - Eliana Garzon
- Epilepsy Clinic, Hospital Sírio-Libanês, São Paulo, Brazil; Department of Neurology, University of São Paulo School of Medicine, Brazil
| | - Fernando Kok
- Mendelics Genomic Analysis, São Paulo, Brazil; Department of Neurology, University of São Paulo School of Medicine, Brazil
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18
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Kessi M, Chen B, Peng J, Tang Y, Olatoutou E, He F, Yang L, Yin F. Intellectual Disability and Potassium Channelopathies: A Systematic Review. Front Genet 2020; 11:614. [PMID: 32655623 PMCID: PMC7324798 DOI: 10.3389/fgene.2020.00614] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Accepted: 05/20/2020] [Indexed: 01/15/2023] Open
Abstract
Intellectual disability (ID) manifests prior to adulthood as severe limitations to intellectual function and adaptive behavior. The role of potassium channelopathies in ID is poorly understood. Therefore, we aimed to evaluate the relationship between ID and potassium channelopathies. We hypothesized that potassium channelopathies are strongly associated with ID initiation, and that both gain- and loss-of-function mutations lead to ID. This systematic review explores the burden of potassium channelopathies, possible mechanisms, advancements using animal models, therapies, and existing gaps. The literature search encompassed both PubMed and Embase up to October 2019. A total of 75 articles describing 338 cases were included in this review. Nineteen channelopathies were identified, affecting the following genes: KCNMA1, KCNN3, KCNT1, KCNT2, KCNJ10, KCNJ6, KCNJ11, KCNA2, KCNA4, KCND3, KCNH1, KCNQ2, KCNAB1, KCNQ3, KCNQ5, KCNC1, KCNB1, KCNC3, and KCTD3. Twelve of these genes presented both gain- and loss-of-function properties, three displayed gain-of-function only, three exhibited loss-of-function only, and one had unknown function. How gain- and loss-of-function mutations can both lead to ID remains largely unknown. We identified only a few animal studies that focused on the mechanisms of ID in relation to potassium channelopathies and some of the few available therapeutic options (channel openers or blockers) appear to offer limited efficacy. In conclusion, potassium channelopathies contribute to the initiation of ID in several instances and this review provides a comprehensive overview of which molecular players are involved in some of the most prominent disease phenotypes.
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Affiliation(s)
- Miriam Kessi
- Department of Pediatrics, Xiangya Hospital, Central South University, Changsha, China.,Hunan Intellectual and Developmental Disabilities Research Center, Changsha, China.,Kilimanjaro Christian Medical University College, Moshi, Tanzania.,Mawenzi Regional Referral Hospital, Moshi, Tanzania
| | - Baiyu Chen
- Department of Pediatrics, Xiangya Hospital, Central South University, Changsha, China.,Hunan Intellectual and Developmental Disabilities Research Center, Changsha, China
| | - Jing Peng
- Department of Pediatrics, Xiangya Hospital, Central South University, Changsha, China.,Hunan Intellectual and Developmental Disabilities Research Center, Changsha, China
| | - Yulin Tang
- Department of Pediatrics, Xiangya Hospital, Central South University, Changsha, China.,Hunan Intellectual and Developmental Disabilities Research Center, Changsha, China
| | - Eleonore Olatoutou
- Department of Pediatrics, Xiangya Hospital, Central South University, Changsha, China.,Hunan Intellectual and Developmental Disabilities Research Center, Changsha, China
| | - Fang He
- Department of Pediatrics, Xiangya Hospital, Central South University, Changsha, China.,Hunan Intellectual and Developmental Disabilities Research Center, Changsha, China
| | - Lifen Yang
- Department of Pediatrics, Xiangya Hospital, Central South University, Changsha, China.,Hunan Intellectual and Developmental Disabilities Research Center, Changsha, China
| | - Fei Yin
- Department of Pediatrics, Xiangya Hospital, Central South University, Changsha, China.,Hunan Intellectual and Developmental Disabilities Research Center, Changsha, China
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19
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Mao X, Bruneau N, Gao Q, Becq H, Jia Z, Xi H, Shu L, Wang H, Szepetowski P, Aniksztejn L. The Epilepsy of Infancy With Migrating Focal Seizures: Identification of de novo Mutations of the KCNT2 Gene That Exert Inhibitory Effects on the Corresponding Heteromeric K Na1.1/K Na1.2 Potassium Channel. Front Cell Neurosci 2020; 14:1. [PMID: 32038177 PMCID: PMC6992647 DOI: 10.3389/fncel.2020.00001] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Accepted: 01/06/2020] [Indexed: 12/21/2022] Open
Abstract
The epilepsy of infancy with migrating focal seizures (EIMFS; previously called Malignant migrating partial seizures of infancy) are early-onset epileptic encephalopathies (EOEE) that associate multifocal ictal discharges and profound psychomotor retardation. EIMFS have a genetic origin and are mostly caused by de novo mutations in the KCNT1 gene, and much more rarely in the KCNT2 gene. KCNT1 and KCNT2 respectively encode the KNa1.1 (Slack) and KNa1.2 (Slick) subunits of the sodium-dependent voltage-gated potassium channel KNa. Functional analyses of the corresponding mutant homomeric channels in vitro suggested gain-of-function effects. Here, we report two novel, de novo truncating mutations of KCNT2: one mutation is frameshift (p.L48Qfs43), is situated in the N-terminal domain, and was found in a patient with EOEE (possibly EIMFS); the other mutation is nonsense (p.K564*), is located in the C-terminal region, and was found in a typical EIMFS patient. Using whole-cell patch-clamp recordings, we have analyzed the functional consequences of those two novel KCNT2 mutations on reconstituted KNa1.2 homomeric and KNa1.1/KNa1.2 heteromeric channels in transfected chinese hamster ovary (CHO) cells. We report that both mutations significantly impacted on KNa function; notably, they decreased the global current density of heteromeric channels by ~25% (p.K564*) and ~55% (p.L48Qfs43). Overall our data emphasize the involvement of KCNT2 in EOEE and provide novel insights into the role of heteromeric KNa channel in the severe KCNT2-related epileptic phenotypes. This may have important implications regarding the elaboration of future treatment.
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Affiliation(s)
- Xiao Mao
- Hunan Provincial Maternal and Child Health Care Hospital, Changsha, China
- NHC Key Laboratory of Birth Defects Research, Prevention and Treatment, Changsha, China
| | - Nadine Bruneau
- INSERM, Aix-Marseille University, INMED, UMR1249, Marseille, France
| | - Quwen Gao
- Department of Epilepsy, General Hospital of Southern Theater Command, Guangzhou, China
| | - Hélène Becq
- INSERM, Aix-Marseille University, INMED, UMR1249, Marseille, France
| | - Zhengjun Jia
- Hunan Provincial Maternal and Child Health Care Hospital, Changsha, China
- NHC Key Laboratory of Birth Defects Research, Prevention and Treatment, Changsha, China
| | - Hui Xi
- Hunan Provincial Maternal and Child Health Care Hospital, Changsha, China
- NHC Key Laboratory of Birth Defects Research, Prevention and Treatment, Changsha, China
| | - Li Shu
- Hunan Provincial Maternal and Child Health Care Hospital, Changsha, China
- NHC Key Laboratory of Birth Defects Research, Prevention and Treatment, Changsha, China
| | - Hua Wang
- Hunan Provincial Maternal and Child Health Care Hospital, Changsha, China
- NHC Key Laboratory of Birth Defects Research, Prevention and Treatment, Changsha, China
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20
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Ali SR, Malone TJ, Zhang Y, Prechova M, Kaczmarek LK. Phactr1 regulates Slack (KCNT1) channels via protein phosphatase 1 (PP1). FASEB J 2020; 34:1591-1601. [PMID: 31914597 PMCID: PMC6956700 DOI: 10.1096/fj.201902366r] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Revised: 11/18/2019] [Accepted: 11/20/2019] [Indexed: 12/14/2022]
Abstract
The Slack (KCNT1) gene encodes sodium-activated potassium channels that are abundantly expressed in the central nervous system. Human mutations alter the function of Slack channels, resulting in epilepsy and intellectual disability. Most of the disease-causing mutations are located in the extended cytoplasmic C-terminus of Slack channels and result in increased Slack current. Previous experiments have shown that the C-terminus of Slack channels binds a number of cytoplasmic signaling proteins. One of these is Phactr1, an actin-binding protein that recruits protein phosphatase 1 (PP1) to certain phosphoprotein substrates. Using co-immunoprecipitation, we found that Phactr1 is required to link the channels to actin. Using patch clamp recordings, we found that co-expression of Phactr1 with wild-type Slack channels reduces the current amplitude but has no effect on Slack channels in which a conserved PKC phosphorylation site (S407) that regulates the current amplitude has been mutated. Furthermore, a Phactr1 mutant that disrupts the binding of PP1 but not that of actin fails to alter Slack currents. Our data suggest that Phactr1 regulates the Slack by linking PP1 to the channel. Targeting Slack-Phactr1 interactions may therefore be helpful in developing the novel therapies for brain disorders associated with the malfunction of Slack channels.
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Affiliation(s)
- Syed Rydwan Ali
- Department of Pharmacology, Yale School of Medicine, New Haven, CT, USA
| | | | - Yalan Zhang
- Department of Pharmacology, Yale School of Medicine, New Haven, CT, USA
| | - Magdalena Prechova
- Signalling and Transcription Group, The Francis Crick Institute, London, UK
- Laboratory of Integrative Biology, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, CZ
| | - Leonard Konrad Kaczmarek
- Department of Pharmacology, Yale School of Medicine, New Haven, CT, USA
- Department of Cellular and Molecular Physiology, Yale School of Medicine, New Haven, CT, USA
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21
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Li P, Halabi CM, Stewart R, Butler A, Brown B, Xia X, Santi C, England S, Ferreira J, Mecham RP, Salkoff L. Sodium-activated potassium channels moderate excitability in vascular smooth muscle. J Physiol 2019; 597:5093-5108. [PMID: 31444905 PMCID: PMC6800802 DOI: 10.1113/jp278279] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Accepted: 08/19/2019] [Indexed: 12/12/2022] Open
Abstract
KEY POINTS We report that a sodium-activated potassium current, IKNa , has been inadvertently overlooked in both conduit and resistance arterial smooth muscle cells. IKNa is a major K+ resting conductance and is absent in cells of IKNa knockout (KO) mice. The phenotype of the IKNa KO is mild hypertension, although KO mice react more strongly than wild-type with raised blood pressure when challenged with vasoconstrictive agents. IKNa is negatively regulated by angiotensin II acting through Gαq protein-coupled receptors. In current clamp, KO arterial smooth muscle cells have easily evoked Ca2+ -dependent action potentials. ABSTRACT Although several potassium currents have been reported to play a role in arterial smooth muscle (ASM), we find that one of the largest contributors to membrane conductance in both conduit and resistance ASMs has been inadvertently overlooked. In the present study, we show that IKNa , a sodium-activated potassium current, contributes a major portion of macroscopic outward current in a critical physiological voltage range that determines intrinsic cell excitability; IKNa is the largest contributor to ASM cell resting conductance. A genetic knockout (KO) mouse strain lacking KNa channels (KCNT1 and KCNT2) shows only a modest hypertensive phenotype. However, acute administration of vasoconstrictive agents such as angiotensin II (Ang II) and phenylephrine results in an abnormally large increase in blood pressure in the KO animals. In wild-type animals Ang II acting through Gαq protein-coupled receptors down-regulates IKNa , which increases the excitability of the ASMs. The complete genetic removal of IKNa in KO mice makes the mutant animal more vulnerable to vasoconstrictive agents, thus producing a paroxysmal-hypertensive phenotype. This may result from the lowering of cell resting K+ conductance allowing the cells to depolarize more readily to a variety of excitable stimuli. Thus, the sodium-activated potassium current may serve to moderate blood pressure in instances of heightened stress. IKNa may represent a new therapeutic target for hypertension and stroke.
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Affiliation(s)
- Ping Li
- Dept. of Neuroscience, Washington University School of Medicine, Saint Louis. MO 63110
- Equal contributors
| | - Carmen M. Halabi
- Dept. of Pediatrics, Washington University School of Medicine, Saint Louis. MO 63110
- Equal contributors
| | - Richard Stewart
- Dept. of Neuroscience, Washington University School of Medicine, Saint Louis. MO 63110
| | - Alice Butler
- Dept. of Neuroscience, Washington University School of Medicine, Saint Louis. MO 63110
| | - Bobbie Brown
- Dept. of Neuroscience, Washington University School of Medicine, Saint Louis. MO 63110
| | - Xiaoming Xia
- Dept. of Anesthesiology, Washington University School of Medicine, Saint Louis. MO 63110
| | - Celia Santi
- Dept. of Neuroscience, Washington University School of Medicine, Saint Louis. MO 63110
- Dept. of OBGYN, Washington University School of Medicine, Saint Louis. MO 63110
| | - Sarah England
- Dept. of OBGYN, Washington University School of Medicine, Saint Louis. MO 63110
| | - Juan Ferreira
- Dept. of Neuroscience, Washington University School of Medicine, Saint Louis. MO 63110
- Dept. of OBGYN, Washington University School of Medicine, Saint Louis. MO 63110
| | - Robert P. Mecham
- Dept. of Cell Biology, Washington University School of Medicine, Saint Louis. MO 63110
| | - Lawrence Salkoff
- Dept. of Neuroscience, Washington University School of Medicine, Saint Louis. MO 63110
- Dept. of Genetics, Washington University School of Medicine, Saint Louis. MO 63110
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22
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Ambrosino P, Soldovieri MV, Bast T, Turnpenny PD, Uhrig S, Biskup S, Döcker M, Fleck T, Mosca I, Manocchio L, Iraci N, Taglialatela M, Lemke JR. De novo gain-of-function variants in KCNT2 as a novel cause of developmental and epileptic encephalopathy. Ann Neurol 2019; 83:1198-1204. [PMID: 29740868 DOI: 10.1002/ana.25248] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2017] [Revised: 04/22/2018] [Accepted: 04/23/2018] [Indexed: 12/30/2022]
Abstract
Variants in several potassium channel genes have been found in developmental and epileptic encephalopathies (DEE). We report on 2 females with de novo variants in KCNT2 with West syndrome followed by Lennox-Gastaut syndrome or with DEE with migrating focal seizures. After in vitro analysis suggested quinidine-responsive gain-of-function effects, we treated 1 of the girls with quinidine add-on therapy and achieved marked clinical improvements. This suggests that the new spectrum of KCNT2-related disorders do not only share similar phenotypic and in vitro functional and pharmacological features with previously known KCNT1-related disorders, but also represents a further example for possible precision medicine approaches. Ann Neurol 2018;83:1198-1204.
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Affiliation(s)
- Paolo Ambrosino
- Department of Medicine and Health Sciences "Vincenzo Tiberio", University of Molise, Campobasso, Italy
| | - Maria Virginia Soldovieri
- Department of Medicine and Health Sciences "Vincenzo Tiberio", University of Molise, Campobasso, Italy
| | - Thomas Bast
- Epilepsy Center Kork, Kehl, Germany.,Faculty of Medicine of the University of Freiburg, Freiburg, Germany
| | - Peter D Turnpenny
- Clinical Genetics, Royal Devon & Exeter NHS Foundation Trust, Exeter, United Kingdom
| | - Sabine Uhrig
- Institute of Clinical Genetics, Klinikum Stuttgart, Stuttgart, Germany
| | - Saskia Biskup
- CeGaT GmbH and Praxis für Humangenetik Tübingen, Tübingen, Germany
| | - Miriam Döcker
- CeGaT GmbH and Praxis für Humangenetik Tübingen, Tübingen, Germany
| | - Thilo Fleck
- University Heart Center Freiburg-Bad Krozingen, Department of Congenital Heart Disease and Pediatric Cardiology, Medical Center-University of Freiburg, Freiburg, Germany
| | - Ilaria Mosca
- Department of Medicine and Health Sciences "Vincenzo Tiberio", University of Molise, Campobasso, Italy
| | - Laura Manocchio
- Department of Medicine and Health Sciences "Vincenzo Tiberio", University of Molise, Campobasso, Italy
| | - Nunzio Iraci
- Department of Pharmacy, University of Salerno, Fisciano, Salerno, Italy
| | | | - Johannes R Lemke
- Institute of Human Genetics, University of Leipzig Hospitals and Clinics, Leipzig, Germany
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23
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Leanza L, Checchetto V, Biasutto L, Rossa A, Costa R, Bachmann M, Zoratti M, Szabo I. Pharmacological modulation of mitochondrial ion channels. Br J Pharmacol 2019; 176:4258-4283. [PMID: 30440086 DOI: 10.1111/bph.14544] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Revised: 10/15/2018] [Accepted: 10/22/2018] [Indexed: 12/17/2022] Open
Abstract
The field of mitochondrial ion channels has undergone a rapid development during the last three decades, due to the molecular identification of some of the channels residing in the outer and inner membranes. Relevant information about the function of these channels in physiological and pathological settings was gained thanks to genetic models for a few, mitochondria-specific channels. However, many ion channels have multiple localizations within the cell, hampering a clear-cut determination of their function by pharmacological means. The present review summarizes our current knowledge about the ins and outs of mitochondrial ion channels, with special focus on the channels that have received much attention in recent years, namely, the voltage-dependent anion channels, the permeability transition pore (also called mitochondrial megachannel), the mitochondrial calcium uniporter and some of the inner membrane-located potassium channels. In addition, possible strategies to overcome the difficulties of specifically targeting mitochondrial channels versus their counterparts active in other membranes are discussed, as well as the possibilities of modulating channel function by small peptides that compete for binding with protein interacting partners. Altogether, these promising tools along with large-scale chemical screenings set up to identify new, specific channel modulators will hopefully allow us to pinpoint the actual function of most mitochondrial ion channels in the near future and to pharmacologically affect important pathologies in which they are involved, such as neurodegeneration, ischaemic damage and cancer. LINKED ARTICLES: This article is part of a themed section on Mitochondrial Pharmacology: Featured Mechanisms and Approaches for Therapy Translation. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.22/issuetoc.
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Affiliation(s)
- Luigi Leanza
- Department of Biology, University of Padova, Padova, Italy
| | | | - Lucia Biasutto
- CNR Institute of Neurosciences, Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - Andrea Rossa
- Department of Chemical Sciences, University of Padova, Padova, Italy
| | - Roberto Costa
- Department of Biology, University of Padova, Padova, Italy
| | | | - Mario Zoratti
- CNR Institute of Neurosciences, Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - Ildiko Szabo
- Department of Biology, University of Padova, Padova, Italy.,CNR Institute of Neurosciences, Department of Biomedical Sciences, University of Padova, Padova, Italy
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24
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Ferreira JJ, Butler A, Stewart R, Gonzalez-Cota AL, Lybaert P, Amazu C, Reinl EL, Wakle-Prabagaran M, Salkoff L, England SK, Santi CM. Oxytocin can regulate myometrial smooth muscle excitability by inhibiting the Na + -activated K + channel, Slo2.1. J Physiol 2018; 597:137-149. [PMID: 30334255 DOI: 10.1113/jp276806] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Accepted: 10/17/2018] [Indexed: 01/05/2023] Open
Abstract
KEY POINTS At the end of pregnancy, the uterus transitions from a quiescent state to a highly contractile state. This transition requires that the uterine (myometrial) smooth muscle cells increase their excitability, although how this occurs is not fully understood. We identified SLO2.1, a potassium channel previously unknown in uterine smooth muscle, as a potential significant contributor to the electrical excitability of myometrial smooth muscle cells. We found that activity of the SLO2.1 channel is negatively regulated by oxytocin via Gαq-protein-coupled receptor activation of protein kinase C. This results in depolarization of the uterine smooth muscle cells and calcium entry, which may contribute to uterine contraction. These findings provide novel insights into a previously unknown mechanism by which oxytocin may act to modulate myometrial smooth muscle cell excitability. Our findings also reveal a new potential pharmacological target for modulating uterine excitability. ABSTRACT During pregnancy, the uterus transitions from a quiescent state to a more excitable contractile state. This is considered to be at least partly a result of changes in the myometrial smooth muscle cell (MSMC) resting membrane potential. However, the ion channels controlling the myometrial resting membrane potential and the mechanism of transition to a more excitable state have not been fully clarified. In the present study, we show that the sodium-activated, high-conductance, potassium leak channel, SLO2.1, is expressed and active at the resting membrane potential in MSMCs. Additionally, we report that SLO2.1 is inhibited by oxytocin binding to the oxytocin receptor. Inhibition of SLO2.1 leads to membrane depolarization and activation of voltage-dependent calcium channels, resulting in calcium influx. The results of the present study reveal that oxytocin may modulate MSMC electrical activity by inhibiting SLO2.1 potassium channels.
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Affiliation(s)
- Juan J Ferreira
- Washington University School of Medicine, Department of Obstetrics and Gynecology, St Louis, MO, USA
| | - Alice Butler
- Washington University School of Medicine, Department of Neuroscience, St Louis, MO, USA
| | - Richard Stewart
- Washington University School of Medicine, Department of Neuroscience, St Louis, MO, USA
| | - Ana Laura Gonzalez-Cota
- Washington University School of Medicine, Department of Obstetrics and Gynecology, St Louis, MO, USA
| | - Pascale Lybaert
- Washington University School of Medicine, Department of Obstetrics and Gynecology, St Louis, MO, USA.,Present address: Laboratoire de Physiologie et Pharmacologie (LAPP), Faculté de Médecine, Université Libre de Bruxelles, Bruxelles, Belgium
| | - Chinwendu Amazu
- Washington University School of Medicine, Department of Obstetrics and Gynecology, St Louis, MO, USA
| | - Erin L Reinl
- Washington University School of Medicine, Department of Obstetrics and Gynecology, St Louis, MO, USA.,Present address: Pharmacology Department, School of Medicine, University of Maryland, Baltimore, MD, USA
| | - Monali Wakle-Prabagaran
- Washington University School of Medicine, Department of Obstetrics and Gynecology, St Louis, MO, USA
| | - Lawrence Salkoff
- Washington University School of Medicine, Department of Neuroscience, St Louis, MO, USA
| | - Sarah K England
- Washington University School of Medicine, Department of Obstetrics and Gynecology, St Louis, MO, USA
| | - Celia M Santi
- Washington University School of Medicine, Department of Obstetrics and Gynecology, St Louis, MO, USA.,Washington University School of Medicine, Department of Neuroscience, St Louis, MO, USA
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25
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Gururaj S, Palmer EE, Sheehan GD, Kandula T, Macintosh R, Ying K, Morris P, Tao J, Dias KR, Zhu Y, Dinger ME, Cowley MJ, Kirk EP, Roscioli T, Sachdev R, Duffey ME, Bye A, Bhattacharjee A. A De Novo Mutation in the Sodium-Activated Potassium Channel KCNT2 Alters Ion Selectivity and Causes Epileptic Encephalopathy. Cell Rep 2018; 21:926-933. [PMID: 29069600 DOI: 10.1016/j.celrep.2017.09.088] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Revised: 06/12/2017] [Accepted: 09/26/2017] [Indexed: 12/31/2022] Open
Abstract
Early infantile epileptic encephalopathies (EOEE) are a debilitating spectrum of disorders associated with cognitive impairments. We present a clinical report of a KCNT2 mutation in an EOEE patient. The de novo heterozygous variant Phe240Leu SLICK was identified by exome sequencing and confirmed by Sanger sequencing. Phe240Leu rSlick and hSLICK channels were electrophysiologically, heterologously characterized to reveal three significant alterations to channel function. First, [Cl-]i sensitivity was reversed in Phe240Leu channels. Second, predominantly K+-selective WT channels were made to favor Na+ over K+ by Phe240Leu. Third, and consequent to altered ion selectivity, Phe240Leu channels had larger inward conductance. Further, rSlick channels induced membrane hyperexcitability when expressed in primary neurons, resembling the cellular seizure phenotype. Taken together, our results confirm that Phe240Leu is a "change-of-function" KCNT2 mutation, demonstrating unusual altered selectivity in KNa channels. These findings establish pathogenicity of the Phe240Leu KCNT2 mutation in the reported EOEE patient.
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Affiliation(s)
- Sushmitha Gururaj
- Pharmacology and Toxicology, University at Buffalo - The State University of New York, Buffalo, NY 14214, USA
| | - Elizabeth Emma Palmer
- Sydney Children's Hospital, Randwick, NSW 2031, Australia; University of New South Wales, Sydney, NSW 2031, Australia; Genetics of Learning Disability Service, Waratah, NSW 2298, Australia
| | - Garrett D Sheehan
- Pharmacology and Toxicology, University at Buffalo - The State University of New York, Buffalo, NY 14214, USA
| | - Tejaswi Kandula
- Sydney Children's Hospital, Randwick, NSW 2031, Australia; University of New South Wales, Sydney, NSW 2031, Australia
| | | | - Kevin Ying
- Kinghorn Centre for Clinical Genomics, Garvan Institute of Medical Research, Sydney, NSW 2298, Australia
| | - Paula Morris
- Kinghorn Centre for Clinical Genomics, Garvan Institute of Medical Research, Sydney, NSW 2298, Australia
| | - Jiang Tao
- Kinghorn Centre for Clinical Genomics, Garvan Institute of Medical Research, Sydney, NSW 2298, Australia
| | - Kerith-Rae Dias
- Kinghorn Centre for Clinical Genomics, Garvan Institute of Medical Research, Sydney, NSW 2298, Australia
| | - Ying Zhu
- Genetics of Learning Disability Service, Waratah, NSW 2298, Australia; SEALS Pathology, Randwick, NSW 2031, Australia
| | - Marcel E Dinger
- University of New South Wales, Sydney, NSW 2031, Australia; Kinghorn Centre for Clinical Genomics, Garvan Institute of Medical Research, Sydney, NSW 2298, Australia
| | - Mark J Cowley
- University of New South Wales, Sydney, NSW 2031, Australia; Kinghorn Centre for Clinical Genomics, Garvan Institute of Medical Research, Sydney, NSW 2298, Australia
| | - Edwin P Kirk
- Sydney Children's Hospital, Randwick, NSW 2031, Australia; University of New South Wales, Sydney, NSW 2031, Australia; SEALS Pathology, Randwick, NSW 2031, Australia
| | - Tony Roscioli
- Sydney Children's Hospital, Randwick, NSW 2031, Australia; University of New South Wales, Sydney, NSW 2031, Australia; SEALS Pathology, Randwick, NSW 2031, Australia
| | - Rani Sachdev
- Sydney Children's Hospital, Randwick, NSW 2031, Australia; University of New South Wales, Sydney, NSW 2031, Australia
| | - Michael E Duffey
- Physiology and Biophysics, University at Buffalo - The State University of New York, Buffalo, NY 14214, USA
| | - Ann Bye
- Sydney Children's Hospital, Randwick, NSW 2031, Australia; University of New South Wales, Sydney, NSW 2031, Australia
| | - Arin Bhattacharjee
- Pharmacology and Toxicology, University at Buffalo - The State University of New York, Buffalo, NY 14214, USA; Program for Neuroscience, University at Buffalo - The State University of New York, Buffalo, NY 14214, USA.
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26
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Smith CO, Wang YT, Nadtochiy SM, Miller JH, Jonas EA, Dirksen RT, Nehrke K, Brookes PS. Cardiac metabolic effects of K Na1.2 channel deletion and evidence for its mitochondrial localization. FASEB J 2018; 32:fj201800139R. [PMID: 29863912 PMCID: PMC6181635 DOI: 10.1096/fj.201800139r] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Accepted: 05/07/2018] [Indexed: 12/18/2022]
Abstract
Controversy surrounds the molecular identity of mitochondrial K+ channels that are important for protection against cardiac ischemia-reperfusion injury. Although KNa1.2 (sodium-activated potassium channel encoded by Kcn2) is necessary for cardioprotection by volatile anesthetics, electrophysiological evidence for a channel of this type in mitochondria is lacking. The endogenous physiological role of a potential mito-KNa1.2 channel is also unclear. In this study, single channel patch-clamp of 27 independent cardiac mitochondrial inner membrane (mitoplast) preparations from wild-type (WT) mice yielded 6 channels matching the known ion sensitivity, ion selectivity, pharmacology, and conductance properties of KNa1.2 (slope conductance, 138 ± 1 pS). However, similar experiments on 40 preparations from Kcnt2-/- mice yielded no such channels. The KNa opener bithionol uncoupled respiration in WT but not Kcnt2-/- cardiomyocytes. Furthermore, when oxidizing only fat as substrate, Kcnt2-/- cardiomyocytes and hearts were less responsive to increases in energetic demand. Kcnt2-/- mice also had elevated body fat, but no baseline differences in the cardiac metabolome. These data support the existence of a cardiac mitochondrial KNa1.2 channel, and a role for cardiac KNa1.2 in regulating metabolism under conditions of high energetic demand.-Smith, C. O., Wang, Y. T., Nadtochiy, S. M., Miller, J. H., Jonas, E. A., Dirksen, R. T., Nehrke, K., Brookes, P. S. Cardiac metabolic effects of KNa1.2 channel deletion and evidence for its mitochondrial localization.
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Affiliation(s)
- Charles O. Smith
- Department of Biochemistry, University of Rochester Medical Center, Rochester, New York, USA
| | - Yves T. Wang
- Department of Anesthesiology and Perioperative Medicine, University of Rochester Medical Center, Rochester, New York, USA
| | - Sergiy M. Nadtochiy
- Department of Anesthesiology and Perioperative Medicine, University of Rochester Medical Center, Rochester, New York, USA
| | - James H. Miller
- Department of Anesthesiology and Perioperative Medicine, University of Rochester Medical Center, Rochester, New York, USA
| | - Elizabeth A. Jonas
- Section of Endocrinology, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Robert T. Dirksen
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, New York, USA
| | - Keith Nehrke
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, New York, USA
- Department of Medicine, University of Rochester Medical Center, Rochester, New York, USA
| | - Paul S. Brookes
- Department of Anesthesiology and Perioperative Medicine, University of Rochester Medical Center, Rochester, New York, USA
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, New York, USA
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27
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Klaerke DA, Tejada MDLA, Christensen VG, Lassen M, Pedersen PA, Calloe K. Reconstitution and Electrophysiological Characterization of Ion Channels in Lipid Bilayers. ACTA ACUST UNITED AC 2018; 81:e37. [PMID: 29927074 DOI: 10.1002/cpph.37] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Detergent-solubilized purified ion channels can be reconstituted into lipid bilayers for electrophysiological analysis. Traditionally, ion channels were inserted into vesicles and subsequently fused with planar "black lipid membranes" formed from lipids dissolved in a hydrophobic solvent such as decane. Provided in this article is a step-by-step guide to reconstitute purified ion channel proteins into giant unilamellar vesicles (GUVs). This procedure results in the formation of proteoliposomes that can be used for planar bilayer formation and electrophysiological characterization of single-channel currents. By using preformed GUVs it is possible to omit the membrane solvent. Compared to traditional preparations, the lipid bilayers formed from GUVs provide an environment that more closely resembles the native cell membrane. Also described is an alternate protocol that entails the production of planar lipid bilayers from GUVs onto which proteins in detergent are added. © 2018 by John Wiley & Sons, Inc.
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Affiliation(s)
- Dan A Klaerke
- Department of Veterinary and Animal Sciences, Section for Anatomy, Biochemistry, and Physiology, University of Copenhagen, Frederiksberg, Denmark
| | - Maria de Los Angeles Tejada
- Department of Veterinary and Animal Sciences, Section for Anatomy, Biochemistry, and Physiology, University of Copenhagen, Frederiksberg, Denmark
| | - Vibeke Grøsfjeld Christensen
- Department of Veterinary and Animal Sciences, Section for Anatomy, Biochemistry, and Physiology, University of Copenhagen, Frederiksberg, Denmark
| | - Mette Lassen
- Department of Veterinary and Animal Sciences, Section for Anatomy, Biochemistry, and Physiology, University of Copenhagen, Frederiksberg, Denmark
| | - Per Amstrup Pedersen
- Department of Biology, Cell Biology and Physiology, University of Copenhagen, Copenhagen, Denmark
| | - Kirstine Calloe
- Department of Veterinary and Animal Sciences, Section for Anatomy, Biochemistry, and Physiology, University of Copenhagen, Frederiksberg, Denmark
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McTague A, Nair U, Malhotra S, Meyer E, Trump N, Gazina EV, Papandreou A, Ngoh A, Ackermann S, Ambegaonkar G, Appleton R, Desurkar A, Eltze C, Kneen R, Kumar AV, Lascelles K, Montgomery T, Ramesh V, Samanta R, Scott RH, Tan J, Whitehouse W, Poduri A, Scheffer IE, Chong WKK, Cross JH, Topf M, Petrou S, Kurian MA. Clinical and molecular characterization of KCNT1-related severe early-onset epilepsy. Neurology 2018; 90:e55-e66. [PMID: 29196579 PMCID: PMC5754647 DOI: 10.1212/wnl.0000000000004762] [Citation(s) in RCA: 76] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Accepted: 09/26/2017] [Indexed: 11/20/2022] Open
Abstract
OBJECTIVE To characterize the phenotypic spectrum, molecular genetic findings, and functional consequences of pathogenic variants in early-onset KCNT1 epilepsy. METHODS We identified a cohort of 31 patients with epilepsy of infancy with migrating focal seizures (EIMFS) and screened for variants in KCNT1 using direct Sanger sequencing, a multiple-gene next-generation sequencing panel, and whole-exome sequencing. Additional patients with non-EIMFS early-onset epilepsy in whom we identified KCNT1 variants on local diagnostic multiple gene panel testing were also included. When possible, we performed homology modeling to predict the putative effects of variants on protein structure and function. We undertook electrophysiologic assessment of mutant KCNT1 channels in a xenopus oocyte model system. RESULTS We identified pathogenic variants in KCNT1 in 12 patients, 4 of which are novel. Most variants occurred de novo. Ten patients had a clinical diagnosis of EIMFS, and the other 2 presented with early-onset severe nocturnal frontal lobe seizures. Three patients had a trial of quinidine with good clinical response in 1 patient. Computational modeling analysis implicates abnormal pore function (F346L) and impaired tetramer formation (F502V) as putative disease mechanisms. All evaluated KCNT1 variants resulted in marked gain of function with significantly increased channel amplitude and variable blockade by quinidine. CONCLUSIONS Gain-of-function KCNT1 pathogenic variants cause a spectrum of severe focal epilepsies with onset in early infancy. Currently, genotype-phenotype correlations are unclear, although clinical outcome is poor for the majority of cases. Further elucidation of disease mechanisms may facilitate the development of targeted treatments, much needed for this pharmacoresistant genetic epilepsy.
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Affiliation(s)
- Amy McTague
- From Molecular Neurosciences (A.M., E.M., A., A.N., M.A.K.), Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health; Department of Neurology (A.M., A., A.N., C.E., J.H.C., M.A.K.) and Neuroradiology (W.K.C.), Great Ormond Street Hospital for Children, London, UK; Florey Institute of Neuroscience and Mental Health (U.N., E.V.G., I.E.S., S.P.), Melbourne, Australia; Department of Biological Sciences (S.M., M.T.), Institute of Structural and Molecular Biology, Birkbeck College, University of London; Regional Molecular Genetics Laboratory (N.T., R.H.S.), North East Thames Regional Genetics Service, and Department of Clinical Genetics (A.V.K., R.H.S.), Great Ormond Street Hospital, London, UK; Department of Paediatric Neurology (S.A.), Red Cross War Memorial Children's Hospital, Cape Town, South Africa; Department of Paediatric Neurology (G.A.), Addenbrooke's Hospital, Cambridge; Roald Dahl EEG Unit (R.A.), Department of Neurology, and Department of Neurology (R.K.), Alder Hey Children's Hospital, Liverpool; Department of Paediatric Neurology (A.D.), Sheffield Children's Hospital; Clinical Neurosciences (C.E., J.H.C.), Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health, London; Institute of Infection and Global Health (R.K.), University of Liverpool; Department of Paediatric Neurology (K.L.), Evelina Children's Hospital, Guys and St. Thomas' NHS Foundation Trust, London; Department of Clinical Genetics (T.M.), Northern Genetics Service; Department of Pediatric Neurology (V.R.), Great North Children's Hospital, Newcastle Upon Tyne; Department of Paediatric Neurology (R.S.), University Hospital Leicester Children's Hospital; Department of Paediatric Neurology (J.T.), Royal Manchester Children's Hospital; Department of Paediatric Neurology (W.W.), Nottingham University Hospitals NHS Trust, UK; Epilepsy Genetics Program (A. Poduri), Department of Neurology, Boston Children's Hospital; Department of Neurology (A. Poduri), Harvard Medical School, Boston, MA; University of Melbourne (I.E.S.), Austin Health and Royal Children's Hospital, Australia; and Department of Medicine (S.P.), Royal Melbourne Hospital, University of Melbourne, Australia. Dr. Malhotra is currently at the Department of Biochemistry, University of Cambridge, UK.
| | - Umesh Nair
- From Molecular Neurosciences (A.M., E.M., A., A.N., M.A.K.), Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health; Department of Neurology (A.M., A., A.N., C.E., J.H.C., M.A.K.) and Neuroradiology (W.K.C.), Great Ormond Street Hospital for Children, London, UK; Florey Institute of Neuroscience and Mental Health (U.N., E.V.G., I.E.S., S.P.), Melbourne, Australia; Department of Biological Sciences (S.M., M.T.), Institute of Structural and Molecular Biology, Birkbeck College, University of London; Regional Molecular Genetics Laboratory (N.T., R.H.S.), North East Thames Regional Genetics Service, and Department of Clinical Genetics (A.V.K., R.H.S.), Great Ormond Street Hospital, London, UK; Department of Paediatric Neurology (S.A.), Red Cross War Memorial Children's Hospital, Cape Town, South Africa; Department of Paediatric Neurology (G.A.), Addenbrooke's Hospital, Cambridge; Roald Dahl EEG Unit (R.A.), Department of Neurology, and Department of Neurology (R.K.), Alder Hey Children's Hospital, Liverpool; Department of Paediatric Neurology (A.D.), Sheffield Children's Hospital; Clinical Neurosciences (C.E., J.H.C.), Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health, London; Institute of Infection and Global Health (R.K.), University of Liverpool; Department of Paediatric Neurology (K.L.), Evelina Children's Hospital, Guys and St. Thomas' NHS Foundation Trust, London; Department of Clinical Genetics (T.M.), Northern Genetics Service; Department of Pediatric Neurology (V.R.), Great North Children's Hospital, Newcastle Upon Tyne; Department of Paediatric Neurology (R.S.), University Hospital Leicester Children's Hospital; Department of Paediatric Neurology (J.T.), Royal Manchester Children's Hospital; Department of Paediatric Neurology (W.W.), Nottingham University Hospitals NHS Trust, UK; Epilepsy Genetics Program (A. Poduri), Department of Neurology, Boston Children's Hospital; Department of Neurology (A. Poduri), Harvard Medical School, Boston, MA; University of Melbourne (I.E.S.), Austin Health and Royal Children's Hospital, Australia; and Department of Medicine (S.P.), Royal Melbourne Hospital, University of Melbourne, Australia. Dr. Malhotra is currently at the Department of Biochemistry, University of Cambridge, UK
| | - Sony Malhotra
- From Molecular Neurosciences (A.M., E.M., A., A.N., M.A.K.), Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health; Department of Neurology (A.M., A., A.N., C.E., J.H.C., M.A.K.) and Neuroradiology (W.K.C.), Great Ormond Street Hospital for Children, London, UK; Florey Institute of Neuroscience and Mental Health (U.N., E.V.G., I.E.S., S.P.), Melbourne, Australia; Department of Biological Sciences (S.M., M.T.), Institute of Structural and Molecular Biology, Birkbeck College, University of London; Regional Molecular Genetics Laboratory (N.T., R.H.S.), North East Thames Regional Genetics Service, and Department of Clinical Genetics (A.V.K., R.H.S.), Great Ormond Street Hospital, London, UK; Department of Paediatric Neurology (S.A.), Red Cross War Memorial Children's Hospital, Cape Town, South Africa; Department of Paediatric Neurology (G.A.), Addenbrooke's Hospital, Cambridge; Roald Dahl EEG Unit (R.A.), Department of Neurology, and Department of Neurology (R.K.), Alder Hey Children's Hospital, Liverpool; Department of Paediatric Neurology (A.D.), Sheffield Children's Hospital; Clinical Neurosciences (C.E., J.H.C.), Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health, London; Institute of Infection and Global Health (R.K.), University of Liverpool; Department of Paediatric Neurology (K.L.), Evelina Children's Hospital, Guys and St. Thomas' NHS Foundation Trust, London; Department of Clinical Genetics (T.M.), Northern Genetics Service; Department of Pediatric Neurology (V.R.), Great North Children's Hospital, Newcastle Upon Tyne; Department of Paediatric Neurology (R.S.), University Hospital Leicester Children's Hospital; Department of Paediatric Neurology (J.T.), Royal Manchester Children's Hospital; Department of Paediatric Neurology (W.W.), Nottingham University Hospitals NHS Trust, UK; Epilepsy Genetics Program (A. Poduri), Department of Neurology, Boston Children's Hospital; Department of Neurology (A. Poduri), Harvard Medical School, Boston, MA; University of Melbourne (I.E.S.), Austin Health and Royal Children's Hospital, Australia; and Department of Medicine (S.P.), Royal Melbourne Hospital, University of Melbourne, Australia. Dr. Malhotra is currently at the Department of Biochemistry, University of Cambridge, UK
| | - Esther Meyer
- From Molecular Neurosciences (A.M., E.M., A., A.N., M.A.K.), Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health; Department of Neurology (A.M., A., A.N., C.E., J.H.C., M.A.K.) and Neuroradiology (W.K.C.), Great Ormond Street Hospital for Children, London, UK; Florey Institute of Neuroscience and Mental Health (U.N., E.V.G., I.E.S., S.P.), Melbourne, Australia; Department of Biological Sciences (S.M., M.T.), Institute of Structural and Molecular Biology, Birkbeck College, University of London; Regional Molecular Genetics Laboratory (N.T., R.H.S.), North East Thames Regional Genetics Service, and Department of Clinical Genetics (A.V.K., R.H.S.), Great Ormond Street Hospital, London, UK; Department of Paediatric Neurology (S.A.), Red Cross War Memorial Children's Hospital, Cape Town, South Africa; Department of Paediatric Neurology (G.A.), Addenbrooke's Hospital, Cambridge; Roald Dahl EEG Unit (R.A.), Department of Neurology, and Department of Neurology (R.K.), Alder Hey Children's Hospital, Liverpool; Department of Paediatric Neurology (A.D.), Sheffield Children's Hospital; Clinical Neurosciences (C.E., J.H.C.), Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health, London; Institute of Infection and Global Health (R.K.), University of Liverpool; Department of Paediatric Neurology (K.L.), Evelina Children's Hospital, Guys and St. Thomas' NHS Foundation Trust, London; Department of Clinical Genetics (T.M.), Northern Genetics Service; Department of Pediatric Neurology (V.R.), Great North Children's Hospital, Newcastle Upon Tyne; Department of Paediatric Neurology (R.S.), University Hospital Leicester Children's Hospital; Department of Paediatric Neurology (J.T.), Royal Manchester Children's Hospital; Department of Paediatric Neurology (W.W.), Nottingham University Hospitals NHS Trust, UK; Epilepsy Genetics Program (A. Poduri), Department of Neurology, Boston Children's Hospital; Department of Neurology (A. Poduri), Harvard Medical School, Boston, MA; University of Melbourne (I.E.S.), Austin Health and Royal Children's Hospital, Australia; and Department of Medicine (S.P.), Royal Melbourne Hospital, University of Melbourne, Australia. Dr. Malhotra is currently at the Department of Biochemistry, University of Cambridge, UK
| | - Natalie Trump
- From Molecular Neurosciences (A.M., E.M., A., A.N., M.A.K.), Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health; Department of Neurology (A.M., A., A.N., C.E., J.H.C., M.A.K.) and Neuroradiology (W.K.C.), Great Ormond Street Hospital for Children, London, UK; Florey Institute of Neuroscience and Mental Health (U.N., E.V.G., I.E.S., S.P.), Melbourne, Australia; Department of Biological Sciences (S.M., M.T.), Institute of Structural and Molecular Biology, Birkbeck College, University of London; Regional Molecular Genetics Laboratory (N.T., R.H.S.), North East Thames Regional Genetics Service, and Department of Clinical Genetics (A.V.K., R.H.S.), Great Ormond Street Hospital, London, UK; Department of Paediatric Neurology (S.A.), Red Cross War Memorial Children's Hospital, Cape Town, South Africa; Department of Paediatric Neurology (G.A.), Addenbrooke's Hospital, Cambridge; Roald Dahl EEG Unit (R.A.), Department of Neurology, and Department of Neurology (R.K.), Alder Hey Children's Hospital, Liverpool; Department of Paediatric Neurology (A.D.), Sheffield Children's Hospital; Clinical Neurosciences (C.E., J.H.C.), Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health, London; Institute of Infection and Global Health (R.K.), University of Liverpool; Department of Paediatric Neurology (K.L.), Evelina Children's Hospital, Guys and St. Thomas' NHS Foundation Trust, London; Department of Clinical Genetics (T.M.), Northern Genetics Service; Department of Pediatric Neurology (V.R.), Great North Children's Hospital, Newcastle Upon Tyne; Department of Paediatric Neurology (R.S.), University Hospital Leicester Children's Hospital; Department of Paediatric Neurology (J.T.), Royal Manchester Children's Hospital; Department of Paediatric Neurology (W.W.), Nottingham University Hospitals NHS Trust, UK; Epilepsy Genetics Program (A. Poduri), Department of Neurology, Boston Children's Hospital; Department of Neurology (A. Poduri), Harvard Medical School, Boston, MA; University of Melbourne (I.E.S.), Austin Health and Royal Children's Hospital, Australia; and Department of Medicine (S.P.), Royal Melbourne Hospital, University of Melbourne, Australia. Dr. Malhotra is currently at the Department of Biochemistry, University of Cambridge, UK
| | - Elena V Gazina
- From Molecular Neurosciences (A.M., E.M., A., A.N., M.A.K.), Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health; Department of Neurology (A.M., A., A.N., C.E., J.H.C., M.A.K.) and Neuroradiology (W.K.C.), Great Ormond Street Hospital for Children, London, UK; Florey Institute of Neuroscience and Mental Health (U.N., E.V.G., I.E.S., S.P.), Melbourne, Australia; Department of Biological Sciences (S.M., M.T.), Institute of Structural and Molecular Biology, Birkbeck College, University of London; Regional Molecular Genetics Laboratory (N.T., R.H.S.), North East Thames Regional Genetics Service, and Department of Clinical Genetics (A.V.K., R.H.S.), Great Ormond Street Hospital, London, UK; Department of Paediatric Neurology (S.A.), Red Cross War Memorial Children's Hospital, Cape Town, South Africa; Department of Paediatric Neurology (G.A.), Addenbrooke's Hospital, Cambridge; Roald Dahl EEG Unit (R.A.), Department of Neurology, and Department of Neurology (R.K.), Alder Hey Children's Hospital, Liverpool; Department of Paediatric Neurology (A.D.), Sheffield Children's Hospital; Clinical Neurosciences (C.E., J.H.C.), Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health, London; Institute of Infection and Global Health (R.K.), University of Liverpool; Department of Paediatric Neurology (K.L.), Evelina Children's Hospital, Guys and St. Thomas' NHS Foundation Trust, London; Department of Clinical Genetics (T.M.), Northern Genetics Service; Department of Pediatric Neurology (V.R.), Great North Children's Hospital, Newcastle Upon Tyne; Department of Paediatric Neurology (R.S.), University Hospital Leicester Children's Hospital; Department of Paediatric Neurology (J.T.), Royal Manchester Children's Hospital; Department of Paediatric Neurology (W.W.), Nottingham University Hospitals NHS Trust, UK; Epilepsy Genetics Program (A. Poduri), Department of Neurology, Boston Children's Hospital; Department of Neurology (A. Poduri), Harvard Medical School, Boston, MA; University of Melbourne (I.E.S.), Austin Health and Royal Children's Hospital, Australia; and Department of Medicine (S.P.), Royal Melbourne Hospital, University of Melbourne, Australia. Dr. Malhotra is currently at the Department of Biochemistry, University of Cambridge, UK
| | - Apostolos Papandreou
- From Molecular Neurosciences (A.M., E.M., A., A.N., M.A.K.), Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health; Department of Neurology (A.M., A., A.N., C.E., J.H.C., M.A.K.) and Neuroradiology (W.K.C.), Great Ormond Street Hospital for Children, London, UK; Florey Institute of Neuroscience and Mental Health (U.N., E.V.G., I.E.S., S.P.), Melbourne, Australia; Department of Biological Sciences (S.M., M.T.), Institute of Structural and Molecular Biology, Birkbeck College, University of London; Regional Molecular Genetics Laboratory (N.T., R.H.S.), North East Thames Regional Genetics Service, and Department of Clinical Genetics (A.V.K., R.H.S.), Great Ormond Street Hospital, London, UK; Department of Paediatric Neurology (S.A.), Red Cross War Memorial Children's Hospital, Cape Town, South Africa; Department of Paediatric Neurology (G.A.), Addenbrooke's Hospital, Cambridge; Roald Dahl EEG Unit (R.A.), Department of Neurology, and Department of Neurology (R.K.), Alder Hey Children's Hospital, Liverpool; Department of Paediatric Neurology (A.D.), Sheffield Children's Hospital; Clinical Neurosciences (C.E., J.H.C.), Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health, London; Institute of Infection and Global Health (R.K.), University of Liverpool; Department of Paediatric Neurology (K.L.), Evelina Children's Hospital, Guys and St. Thomas' NHS Foundation Trust, London; Department of Clinical Genetics (T.M.), Northern Genetics Service; Department of Pediatric Neurology (V.R.), Great North Children's Hospital, Newcastle Upon Tyne; Department of Paediatric Neurology (R.S.), University Hospital Leicester Children's Hospital; Department of Paediatric Neurology (J.T.), Royal Manchester Children's Hospital; Department of Paediatric Neurology (W.W.), Nottingham University Hospitals NHS Trust, UK; Epilepsy Genetics Program (A. Poduri), Department of Neurology, Boston Children's Hospital; Department of Neurology (A. Poduri), Harvard Medical School, Boston, MA; University of Melbourne (I.E.S.), Austin Health and Royal Children's Hospital, Australia; and Department of Medicine (S.P.), Royal Melbourne Hospital, University of Melbourne, Australia. Dr. Malhotra is currently at the Department of Biochemistry, University of Cambridge, UK
| | - Adeline Ngoh
- From Molecular Neurosciences (A.M., E.M., A., A.N., M.A.K.), Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health; Department of Neurology (A.M., A., A.N., C.E., J.H.C., M.A.K.) and Neuroradiology (W.K.C.), Great Ormond Street Hospital for Children, London, UK; Florey Institute of Neuroscience and Mental Health (U.N., E.V.G., I.E.S., S.P.), Melbourne, Australia; Department of Biological Sciences (S.M., M.T.), Institute of Structural and Molecular Biology, Birkbeck College, University of London; Regional Molecular Genetics Laboratory (N.T., R.H.S.), North East Thames Regional Genetics Service, and Department of Clinical Genetics (A.V.K., R.H.S.), Great Ormond Street Hospital, London, UK; Department of Paediatric Neurology (S.A.), Red Cross War Memorial Children's Hospital, Cape Town, South Africa; Department of Paediatric Neurology (G.A.), Addenbrooke's Hospital, Cambridge; Roald Dahl EEG Unit (R.A.), Department of Neurology, and Department of Neurology (R.K.), Alder Hey Children's Hospital, Liverpool; Department of Paediatric Neurology (A.D.), Sheffield Children's Hospital; Clinical Neurosciences (C.E., J.H.C.), Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health, London; Institute of Infection and Global Health (R.K.), University of Liverpool; Department of Paediatric Neurology (K.L.), Evelina Children's Hospital, Guys and St. Thomas' NHS Foundation Trust, London; Department of Clinical Genetics (T.M.), Northern Genetics Service; Department of Pediatric Neurology (V.R.), Great North Children's Hospital, Newcastle Upon Tyne; Department of Paediatric Neurology (R.S.), University Hospital Leicester Children's Hospital; Department of Paediatric Neurology (J.T.), Royal Manchester Children's Hospital; Department of Paediatric Neurology (W.W.), Nottingham University Hospitals NHS Trust, UK; Epilepsy Genetics Program (A. Poduri), Department of Neurology, Boston Children's Hospital; Department of Neurology (A. Poduri), Harvard Medical School, Boston, MA; University of Melbourne (I.E.S.), Austin Health and Royal Children's Hospital, Australia; and Department of Medicine (S.P.), Royal Melbourne Hospital, University of Melbourne, Australia. Dr. Malhotra is currently at the Department of Biochemistry, University of Cambridge, UK
| | - Sally Ackermann
- From Molecular Neurosciences (A.M., E.M., A., A.N., M.A.K.), Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health; Department of Neurology (A.M., A., A.N., C.E., J.H.C., M.A.K.) and Neuroradiology (W.K.C.), Great Ormond Street Hospital for Children, London, UK; Florey Institute of Neuroscience and Mental Health (U.N., E.V.G., I.E.S., S.P.), Melbourne, Australia; Department of Biological Sciences (S.M., M.T.), Institute of Structural and Molecular Biology, Birkbeck College, University of London; Regional Molecular Genetics Laboratory (N.T., R.H.S.), North East Thames Regional Genetics Service, and Department of Clinical Genetics (A.V.K., R.H.S.), Great Ormond Street Hospital, London, UK; Department of Paediatric Neurology (S.A.), Red Cross War Memorial Children's Hospital, Cape Town, South Africa; Department of Paediatric Neurology (G.A.), Addenbrooke's Hospital, Cambridge; Roald Dahl EEG Unit (R.A.), Department of Neurology, and Department of Neurology (R.K.), Alder Hey Children's Hospital, Liverpool; Department of Paediatric Neurology (A.D.), Sheffield Children's Hospital; Clinical Neurosciences (C.E., J.H.C.), Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health, London; Institute of Infection and Global Health (R.K.), University of Liverpool; Department of Paediatric Neurology (K.L.), Evelina Children's Hospital, Guys and St. Thomas' NHS Foundation Trust, London; Department of Clinical Genetics (T.M.), Northern Genetics Service; Department of Pediatric Neurology (V.R.), Great North Children's Hospital, Newcastle Upon Tyne; Department of Paediatric Neurology (R.S.), University Hospital Leicester Children's Hospital; Department of Paediatric Neurology (J.T.), Royal Manchester Children's Hospital; Department of Paediatric Neurology (W.W.), Nottingham University Hospitals NHS Trust, UK; Epilepsy Genetics Program (A. Poduri), Department of Neurology, Boston Children's Hospital; Department of Neurology (A. Poduri), Harvard Medical School, Boston, MA; University of Melbourne (I.E.S.), Austin Health and Royal Children's Hospital, Australia; and Department of Medicine (S.P.), Royal Melbourne Hospital, University of Melbourne, Australia. Dr. Malhotra is currently at the Department of Biochemistry, University of Cambridge, UK
| | - Gautam Ambegaonkar
- From Molecular Neurosciences (A.M., E.M., A., A.N., M.A.K.), Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health; Department of Neurology (A.M., A., A.N., C.E., J.H.C., M.A.K.) and Neuroradiology (W.K.C.), Great Ormond Street Hospital for Children, London, UK; Florey Institute of Neuroscience and Mental Health (U.N., E.V.G., I.E.S., S.P.), Melbourne, Australia; Department of Biological Sciences (S.M., M.T.), Institute of Structural and Molecular Biology, Birkbeck College, University of London; Regional Molecular Genetics Laboratory (N.T., R.H.S.), North East Thames Regional Genetics Service, and Department of Clinical Genetics (A.V.K., R.H.S.), Great Ormond Street Hospital, London, UK; Department of Paediatric Neurology (S.A.), Red Cross War Memorial Children's Hospital, Cape Town, South Africa; Department of Paediatric Neurology (G.A.), Addenbrooke's Hospital, Cambridge; Roald Dahl EEG Unit (R.A.), Department of Neurology, and Department of Neurology (R.K.), Alder Hey Children's Hospital, Liverpool; Department of Paediatric Neurology (A.D.), Sheffield Children's Hospital; Clinical Neurosciences (C.E., J.H.C.), Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health, London; Institute of Infection and Global Health (R.K.), University of Liverpool; Department of Paediatric Neurology (K.L.), Evelina Children's Hospital, Guys and St. Thomas' NHS Foundation Trust, London; Department of Clinical Genetics (T.M.), Northern Genetics Service; Department of Pediatric Neurology (V.R.), Great North Children's Hospital, Newcastle Upon Tyne; Department of Paediatric Neurology (R.S.), University Hospital Leicester Children's Hospital; Department of Paediatric Neurology (J.T.), Royal Manchester Children's Hospital; Department of Paediatric Neurology (W.W.), Nottingham University Hospitals NHS Trust, UK; Epilepsy Genetics Program (A. Poduri), Department of Neurology, Boston Children's Hospital; Department of Neurology (A. Poduri), Harvard Medical School, Boston, MA; University of Melbourne (I.E.S.), Austin Health and Royal Children's Hospital, Australia; and Department of Medicine (S.P.), Royal Melbourne Hospital, University of Melbourne, Australia. Dr. Malhotra is currently at the Department of Biochemistry, University of Cambridge, UK
| | - Richard Appleton
- From Molecular Neurosciences (A.M., E.M., A., A.N., M.A.K.), Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health; Department of Neurology (A.M., A., A.N., C.E., J.H.C., M.A.K.) and Neuroradiology (W.K.C.), Great Ormond Street Hospital for Children, London, UK; Florey Institute of Neuroscience and Mental Health (U.N., E.V.G., I.E.S., S.P.), Melbourne, Australia; Department of Biological Sciences (S.M., M.T.), Institute of Structural and Molecular Biology, Birkbeck College, University of London; Regional Molecular Genetics Laboratory (N.T., R.H.S.), North East Thames Regional Genetics Service, and Department of Clinical Genetics (A.V.K., R.H.S.), Great Ormond Street Hospital, London, UK; Department of Paediatric Neurology (S.A.), Red Cross War Memorial Children's Hospital, Cape Town, South Africa; Department of Paediatric Neurology (G.A.), Addenbrooke's Hospital, Cambridge; Roald Dahl EEG Unit (R.A.), Department of Neurology, and Department of Neurology (R.K.), Alder Hey Children's Hospital, Liverpool; Department of Paediatric Neurology (A.D.), Sheffield Children's Hospital; Clinical Neurosciences (C.E., J.H.C.), Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health, London; Institute of Infection and Global Health (R.K.), University of Liverpool; Department of Paediatric Neurology (K.L.), Evelina Children's Hospital, Guys and St. Thomas' NHS Foundation Trust, London; Department of Clinical Genetics (T.M.), Northern Genetics Service; Department of Pediatric Neurology (V.R.), Great North Children's Hospital, Newcastle Upon Tyne; Department of Paediatric Neurology (R.S.), University Hospital Leicester Children's Hospital; Department of Paediatric Neurology (J.T.), Royal Manchester Children's Hospital; Department of Paediatric Neurology (W.W.), Nottingham University Hospitals NHS Trust, UK; Epilepsy Genetics Program (A. Poduri), Department of Neurology, Boston Children's Hospital; Department of Neurology (A. Poduri), Harvard Medical School, Boston, MA; University of Melbourne (I.E.S.), Austin Health and Royal Children's Hospital, Australia; and Department of Medicine (S.P.), Royal Melbourne Hospital, University of Melbourne, Australia. Dr. Malhotra is currently at the Department of Biochemistry, University of Cambridge, UK
| | - Archana Desurkar
- From Molecular Neurosciences (A.M., E.M., A., A.N., M.A.K.), Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health; Department of Neurology (A.M., A., A.N., C.E., J.H.C., M.A.K.) and Neuroradiology (W.K.C.), Great Ormond Street Hospital for Children, London, UK; Florey Institute of Neuroscience and Mental Health (U.N., E.V.G., I.E.S., S.P.), Melbourne, Australia; Department of Biological Sciences (S.M., M.T.), Institute of Structural and Molecular Biology, Birkbeck College, University of London; Regional Molecular Genetics Laboratory (N.T., R.H.S.), North East Thames Regional Genetics Service, and Department of Clinical Genetics (A.V.K., R.H.S.), Great Ormond Street Hospital, London, UK; Department of Paediatric Neurology (S.A.), Red Cross War Memorial Children's Hospital, Cape Town, South Africa; Department of Paediatric Neurology (G.A.), Addenbrooke's Hospital, Cambridge; Roald Dahl EEG Unit (R.A.), Department of Neurology, and Department of Neurology (R.K.), Alder Hey Children's Hospital, Liverpool; Department of Paediatric Neurology (A.D.), Sheffield Children's Hospital; Clinical Neurosciences (C.E., J.H.C.), Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health, London; Institute of Infection and Global Health (R.K.), University of Liverpool; Department of Paediatric Neurology (K.L.), Evelina Children's Hospital, Guys and St. Thomas' NHS Foundation Trust, London; Department of Clinical Genetics (T.M.), Northern Genetics Service; Department of Pediatric Neurology (V.R.), Great North Children's Hospital, Newcastle Upon Tyne; Department of Paediatric Neurology (R.S.), University Hospital Leicester Children's Hospital; Department of Paediatric Neurology (J.T.), Royal Manchester Children's Hospital; Department of Paediatric Neurology (W.W.), Nottingham University Hospitals NHS Trust, UK; Epilepsy Genetics Program (A. Poduri), Department of Neurology, Boston Children's Hospital; Department of Neurology (A. Poduri), Harvard Medical School, Boston, MA; University of Melbourne (I.E.S.), Austin Health and Royal Children's Hospital, Australia; and Department of Medicine (S.P.), Royal Melbourne Hospital, University of Melbourne, Australia. Dr. Malhotra is currently at the Department of Biochemistry, University of Cambridge, UK
| | - Christin Eltze
- From Molecular Neurosciences (A.M., E.M., A., A.N., M.A.K.), Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health; Department of Neurology (A.M., A., A.N., C.E., J.H.C., M.A.K.) and Neuroradiology (W.K.C.), Great Ormond Street Hospital for Children, London, UK; Florey Institute of Neuroscience and Mental Health (U.N., E.V.G., I.E.S., S.P.), Melbourne, Australia; Department of Biological Sciences (S.M., M.T.), Institute of Structural and Molecular Biology, Birkbeck College, University of London; Regional Molecular Genetics Laboratory (N.T., R.H.S.), North East Thames Regional Genetics Service, and Department of Clinical Genetics (A.V.K., R.H.S.), Great Ormond Street Hospital, London, UK; Department of Paediatric Neurology (S.A.), Red Cross War Memorial Children's Hospital, Cape Town, South Africa; Department of Paediatric Neurology (G.A.), Addenbrooke's Hospital, Cambridge; Roald Dahl EEG Unit (R.A.), Department of Neurology, and Department of Neurology (R.K.), Alder Hey Children's Hospital, Liverpool; Department of Paediatric Neurology (A.D.), Sheffield Children's Hospital; Clinical Neurosciences (C.E., J.H.C.), Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health, London; Institute of Infection and Global Health (R.K.), University of Liverpool; Department of Paediatric Neurology (K.L.), Evelina Children's Hospital, Guys and St. Thomas' NHS Foundation Trust, London; Department of Clinical Genetics (T.M.), Northern Genetics Service; Department of Pediatric Neurology (V.R.), Great North Children's Hospital, Newcastle Upon Tyne; Department of Paediatric Neurology (R.S.), University Hospital Leicester Children's Hospital; Department of Paediatric Neurology (J.T.), Royal Manchester Children's Hospital; Department of Paediatric Neurology (W.W.), Nottingham University Hospitals NHS Trust, UK; Epilepsy Genetics Program (A. Poduri), Department of Neurology, Boston Children's Hospital; Department of Neurology (A. Poduri), Harvard Medical School, Boston, MA; University of Melbourne (I.E.S.), Austin Health and Royal Children's Hospital, Australia; and Department of Medicine (S.P.), Royal Melbourne Hospital, University of Melbourne, Australia. Dr. Malhotra is currently at the Department of Biochemistry, University of Cambridge, UK
| | - Rachel Kneen
- From Molecular Neurosciences (A.M., E.M., A., A.N., M.A.K.), Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health; Department of Neurology (A.M., A., A.N., C.E., J.H.C., M.A.K.) and Neuroradiology (W.K.C.), Great Ormond Street Hospital for Children, London, UK; Florey Institute of Neuroscience and Mental Health (U.N., E.V.G., I.E.S., S.P.), Melbourne, Australia; Department of Biological Sciences (S.M., M.T.), Institute of Structural and Molecular Biology, Birkbeck College, University of London; Regional Molecular Genetics Laboratory (N.T., R.H.S.), North East Thames Regional Genetics Service, and Department of Clinical Genetics (A.V.K., R.H.S.), Great Ormond Street Hospital, London, UK; Department of Paediatric Neurology (S.A.), Red Cross War Memorial Children's Hospital, Cape Town, South Africa; Department of Paediatric Neurology (G.A.), Addenbrooke's Hospital, Cambridge; Roald Dahl EEG Unit (R.A.), Department of Neurology, and Department of Neurology (R.K.), Alder Hey Children's Hospital, Liverpool; Department of Paediatric Neurology (A.D.), Sheffield Children's Hospital; Clinical Neurosciences (C.E., J.H.C.), Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health, London; Institute of Infection and Global Health (R.K.), University of Liverpool; Department of Paediatric Neurology (K.L.), Evelina Children's Hospital, Guys and St. Thomas' NHS Foundation Trust, London; Department of Clinical Genetics (T.M.), Northern Genetics Service; Department of Pediatric Neurology (V.R.), Great North Children's Hospital, Newcastle Upon Tyne; Department of Paediatric Neurology (R.S.), University Hospital Leicester Children's Hospital; Department of Paediatric Neurology (J.T.), Royal Manchester Children's Hospital; Department of Paediatric Neurology (W.W.), Nottingham University Hospitals NHS Trust, UK; Epilepsy Genetics Program (A. Poduri), Department of Neurology, Boston Children's Hospital; Department of Neurology (A. Poduri), Harvard Medical School, Boston, MA; University of Melbourne (I.E.S.), Austin Health and Royal Children's Hospital, Australia; and Department of Medicine (S.P.), Royal Melbourne Hospital, University of Melbourne, Australia. Dr. Malhotra is currently at the Department of Biochemistry, University of Cambridge, UK
| | - Ajith V Kumar
- From Molecular Neurosciences (A.M., E.M., A., A.N., M.A.K.), Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health; Department of Neurology (A.M., A., A.N., C.E., J.H.C., M.A.K.) and Neuroradiology (W.K.C.), Great Ormond Street Hospital for Children, London, UK; Florey Institute of Neuroscience and Mental Health (U.N., E.V.G., I.E.S., S.P.), Melbourne, Australia; Department of Biological Sciences (S.M., M.T.), Institute of Structural and Molecular Biology, Birkbeck College, University of London; Regional Molecular Genetics Laboratory (N.T., R.H.S.), North East Thames Regional Genetics Service, and Department of Clinical Genetics (A.V.K., R.H.S.), Great Ormond Street Hospital, London, UK; Department of Paediatric Neurology (S.A.), Red Cross War Memorial Children's Hospital, Cape Town, South Africa; Department of Paediatric Neurology (G.A.), Addenbrooke's Hospital, Cambridge; Roald Dahl EEG Unit (R.A.), Department of Neurology, and Department of Neurology (R.K.), Alder Hey Children's Hospital, Liverpool; Department of Paediatric Neurology (A.D.), Sheffield Children's Hospital; Clinical Neurosciences (C.E., J.H.C.), Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health, London; Institute of Infection and Global Health (R.K.), University of Liverpool; Department of Paediatric Neurology (K.L.), Evelina Children's Hospital, Guys and St. Thomas' NHS Foundation Trust, London; Department of Clinical Genetics (T.M.), Northern Genetics Service; Department of Pediatric Neurology (V.R.), Great North Children's Hospital, Newcastle Upon Tyne; Department of Paediatric Neurology (R.S.), University Hospital Leicester Children's Hospital; Department of Paediatric Neurology (J.T.), Royal Manchester Children's Hospital; Department of Paediatric Neurology (W.W.), Nottingham University Hospitals NHS Trust, UK; Epilepsy Genetics Program (A. Poduri), Department of Neurology, Boston Children's Hospital; Department of Neurology (A. Poduri), Harvard Medical School, Boston, MA; University of Melbourne (I.E.S.), Austin Health and Royal Children's Hospital, Australia; and Department of Medicine (S.P.), Royal Melbourne Hospital, University of Melbourne, Australia. Dr. Malhotra is currently at the Department of Biochemistry, University of Cambridge, UK
| | - Karine Lascelles
- From Molecular Neurosciences (A.M., E.M., A., A.N., M.A.K.), Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health; Department of Neurology (A.M., A., A.N., C.E., J.H.C., M.A.K.) and Neuroradiology (W.K.C.), Great Ormond Street Hospital for Children, London, UK; Florey Institute of Neuroscience and Mental Health (U.N., E.V.G., I.E.S., S.P.), Melbourne, Australia; Department of Biological Sciences (S.M., M.T.), Institute of Structural and Molecular Biology, Birkbeck College, University of London; Regional Molecular Genetics Laboratory (N.T., R.H.S.), North East Thames Regional Genetics Service, and Department of Clinical Genetics (A.V.K., R.H.S.), Great Ormond Street Hospital, London, UK; Department of Paediatric Neurology (S.A.), Red Cross War Memorial Children's Hospital, Cape Town, South Africa; Department of Paediatric Neurology (G.A.), Addenbrooke's Hospital, Cambridge; Roald Dahl EEG Unit (R.A.), Department of Neurology, and Department of Neurology (R.K.), Alder Hey Children's Hospital, Liverpool; Department of Paediatric Neurology (A.D.), Sheffield Children's Hospital; Clinical Neurosciences (C.E., J.H.C.), Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health, London; Institute of Infection and Global Health (R.K.), University of Liverpool; Department of Paediatric Neurology (K.L.), Evelina Children's Hospital, Guys and St. Thomas' NHS Foundation Trust, London; Department of Clinical Genetics (T.M.), Northern Genetics Service; Department of Pediatric Neurology (V.R.), Great North Children's Hospital, Newcastle Upon Tyne; Department of Paediatric Neurology (R.S.), University Hospital Leicester Children's Hospital; Department of Paediatric Neurology (J.T.), Royal Manchester Children's Hospital; Department of Paediatric Neurology (W.W.), Nottingham University Hospitals NHS Trust, UK; Epilepsy Genetics Program (A. Poduri), Department of Neurology, Boston Children's Hospital; Department of Neurology (A. Poduri), Harvard Medical School, Boston, MA; University of Melbourne (I.E.S.), Austin Health and Royal Children's Hospital, Australia; and Department of Medicine (S.P.), Royal Melbourne Hospital, University of Melbourne, Australia. Dr. Malhotra is currently at the Department of Biochemistry, University of Cambridge, UK
| | - Tara Montgomery
- From Molecular Neurosciences (A.M., E.M., A., A.N., M.A.K.), Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health; Department of Neurology (A.M., A., A.N., C.E., J.H.C., M.A.K.) and Neuroradiology (W.K.C.), Great Ormond Street Hospital for Children, London, UK; Florey Institute of Neuroscience and Mental Health (U.N., E.V.G., I.E.S., S.P.), Melbourne, Australia; Department of Biological Sciences (S.M., M.T.), Institute of Structural and Molecular Biology, Birkbeck College, University of London; Regional Molecular Genetics Laboratory (N.T., R.H.S.), North East Thames Regional Genetics Service, and Department of Clinical Genetics (A.V.K., R.H.S.), Great Ormond Street Hospital, London, UK; Department of Paediatric Neurology (S.A.), Red Cross War Memorial Children's Hospital, Cape Town, South Africa; Department of Paediatric Neurology (G.A.), Addenbrooke's Hospital, Cambridge; Roald Dahl EEG Unit (R.A.), Department of Neurology, and Department of Neurology (R.K.), Alder Hey Children's Hospital, Liverpool; Department of Paediatric Neurology (A.D.), Sheffield Children's Hospital; Clinical Neurosciences (C.E., J.H.C.), Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health, London; Institute of Infection and Global Health (R.K.), University of Liverpool; Department of Paediatric Neurology (K.L.), Evelina Children's Hospital, Guys and St. Thomas' NHS Foundation Trust, London; Department of Clinical Genetics (T.M.), Northern Genetics Service; Department of Pediatric Neurology (V.R.), Great North Children's Hospital, Newcastle Upon Tyne; Department of Paediatric Neurology (R.S.), University Hospital Leicester Children's Hospital; Department of Paediatric Neurology (J.T.), Royal Manchester Children's Hospital; Department of Paediatric Neurology (W.W.), Nottingham University Hospitals NHS Trust, UK; Epilepsy Genetics Program (A. Poduri), Department of Neurology, Boston Children's Hospital; Department of Neurology (A. Poduri), Harvard Medical School, Boston, MA; University of Melbourne (I.E.S.), Austin Health and Royal Children's Hospital, Australia; and Department of Medicine (S.P.), Royal Melbourne Hospital, University of Melbourne, Australia. Dr. Malhotra is currently at the Department of Biochemistry, University of Cambridge, UK
| | - Venkateswaran Ramesh
- From Molecular Neurosciences (A.M., E.M., A., A.N., M.A.K.), Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health; Department of Neurology (A.M., A., A.N., C.E., J.H.C., M.A.K.) and Neuroradiology (W.K.C.), Great Ormond Street Hospital for Children, London, UK; Florey Institute of Neuroscience and Mental Health (U.N., E.V.G., I.E.S., S.P.), Melbourne, Australia; Department of Biological Sciences (S.M., M.T.), Institute of Structural and Molecular Biology, Birkbeck College, University of London; Regional Molecular Genetics Laboratory (N.T., R.H.S.), North East Thames Regional Genetics Service, and Department of Clinical Genetics (A.V.K., R.H.S.), Great Ormond Street Hospital, London, UK; Department of Paediatric Neurology (S.A.), Red Cross War Memorial Children's Hospital, Cape Town, South Africa; Department of Paediatric Neurology (G.A.), Addenbrooke's Hospital, Cambridge; Roald Dahl EEG Unit (R.A.), Department of Neurology, and Department of Neurology (R.K.), Alder Hey Children's Hospital, Liverpool; Department of Paediatric Neurology (A.D.), Sheffield Children's Hospital; Clinical Neurosciences (C.E., J.H.C.), Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health, London; Institute of Infection and Global Health (R.K.), University of Liverpool; Department of Paediatric Neurology (K.L.), Evelina Children's Hospital, Guys and St. Thomas' NHS Foundation Trust, London; Department of Clinical Genetics (T.M.), Northern Genetics Service; Department of Pediatric Neurology (V.R.), Great North Children's Hospital, Newcastle Upon Tyne; Department of Paediatric Neurology (R.S.), University Hospital Leicester Children's Hospital; Department of Paediatric Neurology (J.T.), Royal Manchester Children's Hospital; Department of Paediatric Neurology (W.W.), Nottingham University Hospitals NHS Trust, UK; Epilepsy Genetics Program (A. Poduri), Department of Neurology, Boston Children's Hospital; Department of Neurology (A. Poduri), Harvard Medical School, Boston, MA; University of Melbourne (I.E.S.), Austin Health and Royal Children's Hospital, Australia; and Department of Medicine (S.P.), Royal Melbourne Hospital, University of Melbourne, Australia. Dr. Malhotra is currently at the Department of Biochemistry, University of Cambridge, UK
| | - Rajib Samanta
- From Molecular Neurosciences (A.M., E.M., A., A.N., M.A.K.), Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health; Department of Neurology (A.M., A., A.N., C.E., J.H.C., M.A.K.) and Neuroradiology (W.K.C.), Great Ormond Street Hospital for Children, London, UK; Florey Institute of Neuroscience and Mental Health (U.N., E.V.G., I.E.S., S.P.), Melbourne, Australia; Department of Biological Sciences (S.M., M.T.), Institute of Structural and Molecular Biology, Birkbeck College, University of London; Regional Molecular Genetics Laboratory (N.T., R.H.S.), North East Thames Regional Genetics Service, and Department of Clinical Genetics (A.V.K., R.H.S.), Great Ormond Street Hospital, London, UK; Department of Paediatric Neurology (S.A.), Red Cross War Memorial Children's Hospital, Cape Town, South Africa; Department of Paediatric Neurology (G.A.), Addenbrooke's Hospital, Cambridge; Roald Dahl EEG Unit (R.A.), Department of Neurology, and Department of Neurology (R.K.), Alder Hey Children's Hospital, Liverpool; Department of Paediatric Neurology (A.D.), Sheffield Children's Hospital; Clinical Neurosciences (C.E., J.H.C.), Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health, London; Institute of Infection and Global Health (R.K.), University of Liverpool; Department of Paediatric Neurology (K.L.), Evelina Children's Hospital, Guys and St. Thomas' NHS Foundation Trust, London; Department of Clinical Genetics (T.M.), Northern Genetics Service; Department of Pediatric Neurology (V.R.), Great North Children's Hospital, Newcastle Upon Tyne; Department of Paediatric Neurology (R.S.), University Hospital Leicester Children's Hospital; Department of Paediatric Neurology (J.T.), Royal Manchester Children's Hospital; Department of Paediatric Neurology (W.W.), Nottingham University Hospitals NHS Trust, UK; Epilepsy Genetics Program (A. Poduri), Department of Neurology, Boston Children's Hospital; Department of Neurology (A. Poduri), Harvard Medical School, Boston, MA; University of Melbourne (I.E.S.), Austin Health and Royal Children's Hospital, Australia; and Department of Medicine (S.P.), Royal Melbourne Hospital, University of Melbourne, Australia. Dr. Malhotra is currently at the Department of Biochemistry, University of Cambridge, UK
| | - Richard H Scott
- From Molecular Neurosciences (A.M., E.M., A., A.N., M.A.K.), Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health; Department of Neurology (A.M., A., A.N., C.E., J.H.C., M.A.K.) and Neuroradiology (W.K.C.), Great Ormond Street Hospital for Children, London, UK; Florey Institute of Neuroscience and Mental Health (U.N., E.V.G., I.E.S., S.P.), Melbourne, Australia; Department of Biological Sciences (S.M., M.T.), Institute of Structural and Molecular Biology, Birkbeck College, University of London; Regional Molecular Genetics Laboratory (N.T., R.H.S.), North East Thames Regional Genetics Service, and Department of Clinical Genetics (A.V.K., R.H.S.), Great Ormond Street Hospital, London, UK; Department of Paediatric Neurology (S.A.), Red Cross War Memorial Children's Hospital, Cape Town, South Africa; Department of Paediatric Neurology (G.A.), Addenbrooke's Hospital, Cambridge; Roald Dahl EEG Unit (R.A.), Department of Neurology, and Department of Neurology (R.K.), Alder Hey Children's Hospital, Liverpool; Department of Paediatric Neurology (A.D.), Sheffield Children's Hospital; Clinical Neurosciences (C.E., J.H.C.), Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health, London; Institute of Infection and Global Health (R.K.), University of Liverpool; Department of Paediatric Neurology (K.L.), Evelina Children's Hospital, Guys and St. Thomas' NHS Foundation Trust, London; Department of Clinical Genetics (T.M.), Northern Genetics Service; Department of Pediatric Neurology (V.R.), Great North Children's Hospital, Newcastle Upon Tyne; Department of Paediatric Neurology (R.S.), University Hospital Leicester Children's Hospital; Department of Paediatric Neurology (J.T.), Royal Manchester Children's Hospital; Department of Paediatric Neurology (W.W.), Nottingham University Hospitals NHS Trust, UK; Epilepsy Genetics Program (A. Poduri), Department of Neurology, Boston Children's Hospital; Department of Neurology (A. Poduri), Harvard Medical School, Boston, MA; University of Melbourne (I.E.S.), Austin Health and Royal Children's Hospital, Australia; and Department of Medicine (S.P.), Royal Melbourne Hospital, University of Melbourne, Australia. Dr. Malhotra is currently at the Department of Biochemistry, University of Cambridge, UK
| | - Jeen Tan
- From Molecular Neurosciences (A.M., E.M., A., A.N., M.A.K.), Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health; Department of Neurology (A.M., A., A.N., C.E., J.H.C., M.A.K.) and Neuroradiology (W.K.C.), Great Ormond Street Hospital for Children, London, UK; Florey Institute of Neuroscience and Mental Health (U.N., E.V.G., I.E.S., S.P.), Melbourne, Australia; Department of Biological Sciences (S.M., M.T.), Institute of Structural and Molecular Biology, Birkbeck College, University of London; Regional Molecular Genetics Laboratory (N.T., R.H.S.), North East Thames Regional Genetics Service, and Department of Clinical Genetics (A.V.K., R.H.S.), Great Ormond Street Hospital, London, UK; Department of Paediatric Neurology (S.A.), Red Cross War Memorial Children's Hospital, Cape Town, South Africa; Department of Paediatric Neurology (G.A.), Addenbrooke's Hospital, Cambridge; Roald Dahl EEG Unit (R.A.), Department of Neurology, and Department of Neurology (R.K.), Alder Hey Children's Hospital, Liverpool; Department of Paediatric Neurology (A.D.), Sheffield Children's Hospital; Clinical Neurosciences (C.E., J.H.C.), Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health, London; Institute of Infection and Global Health (R.K.), University of Liverpool; Department of Paediatric Neurology (K.L.), Evelina Children's Hospital, Guys and St. Thomas' NHS Foundation Trust, London; Department of Clinical Genetics (T.M.), Northern Genetics Service; Department of Pediatric Neurology (V.R.), Great North Children's Hospital, Newcastle Upon Tyne; Department of Paediatric Neurology (R.S.), University Hospital Leicester Children's Hospital; Department of Paediatric Neurology (J.T.), Royal Manchester Children's Hospital; Department of Paediatric Neurology (W.W.), Nottingham University Hospitals NHS Trust, UK; Epilepsy Genetics Program (A. Poduri), Department of Neurology, Boston Children's Hospital; Department of Neurology (A. Poduri), Harvard Medical School, Boston, MA; University of Melbourne (I.E.S.), Austin Health and Royal Children's Hospital, Australia; and Department of Medicine (S.P.), Royal Melbourne Hospital, University of Melbourne, Australia. Dr. Malhotra is currently at the Department of Biochemistry, University of Cambridge, UK
| | - William Whitehouse
- From Molecular Neurosciences (A.M., E.M., A., A.N., M.A.K.), Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health; Department of Neurology (A.M., A., A.N., C.E., J.H.C., M.A.K.) and Neuroradiology (W.K.C.), Great Ormond Street Hospital for Children, London, UK; Florey Institute of Neuroscience and Mental Health (U.N., E.V.G., I.E.S., S.P.), Melbourne, Australia; Department of Biological Sciences (S.M., M.T.), Institute of Structural and Molecular Biology, Birkbeck College, University of London; Regional Molecular Genetics Laboratory (N.T., R.H.S.), North East Thames Regional Genetics Service, and Department of Clinical Genetics (A.V.K., R.H.S.), Great Ormond Street Hospital, London, UK; Department of Paediatric Neurology (S.A.), Red Cross War Memorial Children's Hospital, Cape Town, South Africa; Department of Paediatric Neurology (G.A.), Addenbrooke's Hospital, Cambridge; Roald Dahl EEG Unit (R.A.), Department of Neurology, and Department of Neurology (R.K.), Alder Hey Children's Hospital, Liverpool; Department of Paediatric Neurology (A.D.), Sheffield Children's Hospital; Clinical Neurosciences (C.E., J.H.C.), Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health, London; Institute of Infection and Global Health (R.K.), University of Liverpool; Department of Paediatric Neurology (K.L.), Evelina Children's Hospital, Guys and St. Thomas' NHS Foundation Trust, London; Department of Clinical Genetics (T.M.), Northern Genetics Service; Department of Pediatric Neurology (V.R.), Great North Children's Hospital, Newcastle Upon Tyne; Department of Paediatric Neurology (R.S.), University Hospital Leicester Children's Hospital; Department of Paediatric Neurology (J.T.), Royal Manchester Children's Hospital; Department of Paediatric Neurology (W.W.), Nottingham University Hospitals NHS Trust, UK; Epilepsy Genetics Program (A. Poduri), Department of Neurology, Boston Children's Hospital; Department of Neurology (A. Poduri), Harvard Medical School, Boston, MA; University of Melbourne (I.E.S.), Austin Health and Royal Children's Hospital, Australia; and Department of Medicine (S.P.), Royal Melbourne Hospital, University of Melbourne, Australia. Dr. Malhotra is currently at the Department of Biochemistry, University of Cambridge, UK
| | - Annapurna Poduri
- From Molecular Neurosciences (A.M., E.M., A., A.N., M.A.K.), Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health; Department of Neurology (A.M., A., A.N., C.E., J.H.C., M.A.K.) and Neuroradiology (W.K.C.), Great Ormond Street Hospital for Children, London, UK; Florey Institute of Neuroscience and Mental Health (U.N., E.V.G., I.E.S., S.P.), Melbourne, Australia; Department of Biological Sciences (S.M., M.T.), Institute of Structural and Molecular Biology, Birkbeck College, University of London; Regional Molecular Genetics Laboratory (N.T., R.H.S.), North East Thames Regional Genetics Service, and Department of Clinical Genetics (A.V.K., R.H.S.), Great Ormond Street Hospital, London, UK; Department of Paediatric Neurology (S.A.), Red Cross War Memorial Children's Hospital, Cape Town, South Africa; Department of Paediatric Neurology (G.A.), Addenbrooke's Hospital, Cambridge; Roald Dahl EEG Unit (R.A.), Department of Neurology, and Department of Neurology (R.K.), Alder Hey Children's Hospital, Liverpool; Department of Paediatric Neurology (A.D.), Sheffield Children's Hospital; Clinical Neurosciences (C.E., J.H.C.), Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health, London; Institute of Infection and Global Health (R.K.), University of Liverpool; Department of Paediatric Neurology (K.L.), Evelina Children's Hospital, Guys and St. Thomas' NHS Foundation Trust, London; Department of Clinical Genetics (T.M.), Northern Genetics Service; Department of Pediatric Neurology (V.R.), Great North Children's Hospital, Newcastle Upon Tyne; Department of Paediatric Neurology (R.S.), University Hospital Leicester Children's Hospital; Department of Paediatric Neurology (J.T.), Royal Manchester Children's Hospital; Department of Paediatric Neurology (W.W.), Nottingham University Hospitals NHS Trust, UK; Epilepsy Genetics Program (A. Poduri), Department of Neurology, Boston Children's Hospital; Department of Neurology (A. Poduri), Harvard Medical School, Boston, MA; University of Melbourne (I.E.S.), Austin Health and Royal Children's Hospital, Australia; and Department of Medicine (S.P.), Royal Melbourne Hospital, University of Melbourne, Australia. Dr. Malhotra is currently at the Department of Biochemistry, University of Cambridge, UK
| | - Ingrid E Scheffer
- From Molecular Neurosciences (A.M., E.M., A., A.N., M.A.K.), Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health; Department of Neurology (A.M., A., A.N., C.E., J.H.C., M.A.K.) and Neuroradiology (W.K.C.), Great Ormond Street Hospital for Children, London, UK; Florey Institute of Neuroscience and Mental Health (U.N., E.V.G., I.E.S., S.P.), Melbourne, Australia; Department of Biological Sciences (S.M., M.T.), Institute of Structural and Molecular Biology, Birkbeck College, University of London; Regional Molecular Genetics Laboratory (N.T., R.H.S.), North East Thames Regional Genetics Service, and Department of Clinical Genetics (A.V.K., R.H.S.), Great Ormond Street Hospital, London, UK; Department of Paediatric Neurology (S.A.), Red Cross War Memorial Children's Hospital, Cape Town, South Africa; Department of Paediatric Neurology (G.A.), Addenbrooke's Hospital, Cambridge; Roald Dahl EEG Unit (R.A.), Department of Neurology, and Department of Neurology (R.K.), Alder Hey Children's Hospital, Liverpool; Department of Paediatric Neurology (A.D.), Sheffield Children's Hospital; Clinical Neurosciences (C.E., J.H.C.), Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health, London; Institute of Infection and Global Health (R.K.), University of Liverpool; Department of Paediatric Neurology (K.L.), Evelina Children's Hospital, Guys and St. Thomas' NHS Foundation Trust, London; Department of Clinical Genetics (T.M.), Northern Genetics Service; Department of Pediatric Neurology (V.R.), Great North Children's Hospital, Newcastle Upon Tyne; Department of Paediatric Neurology (R.S.), University Hospital Leicester Children's Hospital; Department of Paediatric Neurology (J.T.), Royal Manchester Children's Hospital; Department of Paediatric Neurology (W.W.), Nottingham University Hospitals NHS Trust, UK; Epilepsy Genetics Program (A. Poduri), Department of Neurology, Boston Children's Hospital; Department of Neurology (A. Poduri), Harvard Medical School, Boston, MA; University of Melbourne (I.E.S.), Austin Health and Royal Children's Hospital, Australia; and Department of Medicine (S.P.), Royal Melbourne Hospital, University of Melbourne, Australia. Dr. Malhotra is currently at the Department of Biochemistry, University of Cambridge, UK
| | - W K Kling Chong
- From Molecular Neurosciences (A.M., E.M., A., A.N., M.A.K.), Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health; Department of Neurology (A.M., A., A.N., C.E., J.H.C., M.A.K.) and Neuroradiology (W.K.C.), Great Ormond Street Hospital for Children, London, UK; Florey Institute of Neuroscience and Mental Health (U.N., E.V.G., I.E.S., S.P.), Melbourne, Australia; Department of Biological Sciences (S.M., M.T.), Institute of Structural and Molecular Biology, Birkbeck College, University of London; Regional Molecular Genetics Laboratory (N.T., R.H.S.), North East Thames Regional Genetics Service, and Department of Clinical Genetics (A.V.K., R.H.S.), Great Ormond Street Hospital, London, UK; Department of Paediatric Neurology (S.A.), Red Cross War Memorial Children's Hospital, Cape Town, South Africa; Department of Paediatric Neurology (G.A.), Addenbrooke's Hospital, Cambridge; Roald Dahl EEG Unit (R.A.), Department of Neurology, and Department of Neurology (R.K.), Alder Hey Children's Hospital, Liverpool; Department of Paediatric Neurology (A.D.), Sheffield Children's Hospital; Clinical Neurosciences (C.E., J.H.C.), Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health, London; Institute of Infection and Global Health (R.K.), University of Liverpool; Department of Paediatric Neurology (K.L.), Evelina Children's Hospital, Guys and St. Thomas' NHS Foundation Trust, London; Department of Clinical Genetics (T.M.), Northern Genetics Service; Department of Pediatric Neurology (V.R.), Great North Children's Hospital, Newcastle Upon Tyne; Department of Paediatric Neurology (R.S.), University Hospital Leicester Children's Hospital; Department of Paediatric Neurology (J.T.), Royal Manchester Children's Hospital; Department of Paediatric Neurology (W.W.), Nottingham University Hospitals NHS Trust, UK; Epilepsy Genetics Program (A. Poduri), Department of Neurology, Boston Children's Hospital; Department of Neurology (A. Poduri), Harvard Medical School, Boston, MA; University of Melbourne (I.E.S.), Austin Health and Royal Children's Hospital, Australia; and Department of Medicine (S.P.), Royal Melbourne Hospital, University of Melbourne, Australia. Dr. Malhotra is currently at the Department of Biochemistry, University of Cambridge, UK
| | - J Helen Cross
- From Molecular Neurosciences (A.M., E.M., A., A.N., M.A.K.), Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health; Department of Neurology (A.M., A., A.N., C.E., J.H.C., M.A.K.) and Neuroradiology (W.K.C.), Great Ormond Street Hospital for Children, London, UK; Florey Institute of Neuroscience and Mental Health (U.N., E.V.G., I.E.S., S.P.), Melbourne, Australia; Department of Biological Sciences (S.M., M.T.), Institute of Structural and Molecular Biology, Birkbeck College, University of London; Regional Molecular Genetics Laboratory (N.T., R.H.S.), North East Thames Regional Genetics Service, and Department of Clinical Genetics (A.V.K., R.H.S.), Great Ormond Street Hospital, London, UK; Department of Paediatric Neurology (S.A.), Red Cross War Memorial Children's Hospital, Cape Town, South Africa; Department of Paediatric Neurology (G.A.), Addenbrooke's Hospital, Cambridge; Roald Dahl EEG Unit (R.A.), Department of Neurology, and Department of Neurology (R.K.), Alder Hey Children's Hospital, Liverpool; Department of Paediatric Neurology (A.D.), Sheffield Children's Hospital; Clinical Neurosciences (C.E., J.H.C.), Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health, London; Institute of Infection and Global Health (R.K.), University of Liverpool; Department of Paediatric Neurology (K.L.), Evelina Children's Hospital, Guys and St. Thomas' NHS Foundation Trust, London; Department of Clinical Genetics (T.M.), Northern Genetics Service; Department of Pediatric Neurology (V.R.), Great North Children's Hospital, Newcastle Upon Tyne; Department of Paediatric Neurology (R.S.), University Hospital Leicester Children's Hospital; Department of Paediatric Neurology (J.T.), Royal Manchester Children's Hospital; Department of Paediatric Neurology (W.W.), Nottingham University Hospitals NHS Trust, UK; Epilepsy Genetics Program (A. Poduri), Department of Neurology, Boston Children's Hospital; Department of Neurology (A. Poduri), Harvard Medical School, Boston, MA; University of Melbourne (I.E.S.), Austin Health and Royal Children's Hospital, Australia; and Department of Medicine (S.P.), Royal Melbourne Hospital, University of Melbourne, Australia. Dr. Malhotra is currently at the Department of Biochemistry, University of Cambridge, UK
| | - Maya Topf
- From Molecular Neurosciences (A.M., E.M., A., A.N., M.A.K.), Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health; Department of Neurology (A.M., A., A.N., C.E., J.H.C., M.A.K.) and Neuroradiology (W.K.C.), Great Ormond Street Hospital for Children, London, UK; Florey Institute of Neuroscience and Mental Health (U.N., E.V.G., I.E.S., S.P.), Melbourne, Australia; Department of Biological Sciences (S.M., M.T.), Institute of Structural and Molecular Biology, Birkbeck College, University of London; Regional Molecular Genetics Laboratory (N.T., R.H.S.), North East Thames Regional Genetics Service, and Department of Clinical Genetics (A.V.K., R.H.S.), Great Ormond Street Hospital, London, UK; Department of Paediatric Neurology (S.A.), Red Cross War Memorial Children's Hospital, Cape Town, South Africa; Department of Paediatric Neurology (G.A.), Addenbrooke's Hospital, Cambridge; Roald Dahl EEG Unit (R.A.), Department of Neurology, and Department of Neurology (R.K.), Alder Hey Children's Hospital, Liverpool; Department of Paediatric Neurology (A.D.), Sheffield Children's Hospital; Clinical Neurosciences (C.E., J.H.C.), Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health, London; Institute of Infection and Global Health (R.K.), University of Liverpool; Department of Paediatric Neurology (K.L.), Evelina Children's Hospital, Guys and St. Thomas' NHS Foundation Trust, London; Department of Clinical Genetics (T.M.), Northern Genetics Service; Department of Pediatric Neurology (V.R.), Great North Children's Hospital, Newcastle Upon Tyne; Department of Paediatric Neurology (R.S.), University Hospital Leicester Children's Hospital; Department of Paediatric Neurology (J.T.), Royal Manchester Children's Hospital; Department of Paediatric Neurology (W.W.), Nottingham University Hospitals NHS Trust, UK; Epilepsy Genetics Program (A. Poduri), Department of Neurology, Boston Children's Hospital; Department of Neurology (A. Poduri), Harvard Medical School, Boston, MA; University of Melbourne (I.E.S.), Austin Health and Royal Children's Hospital, Australia; and Department of Medicine (S.P.), Royal Melbourne Hospital, University of Melbourne, Australia. Dr. Malhotra is currently at the Department of Biochemistry, University of Cambridge, UK
| | - Steven Petrou
- From Molecular Neurosciences (A.M., E.M., A., A.N., M.A.K.), Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health; Department of Neurology (A.M., A., A.N., C.E., J.H.C., M.A.K.) and Neuroradiology (W.K.C.), Great Ormond Street Hospital for Children, London, UK; Florey Institute of Neuroscience and Mental Health (U.N., E.V.G., I.E.S., S.P.), Melbourne, Australia; Department of Biological Sciences (S.M., M.T.), Institute of Structural and Molecular Biology, Birkbeck College, University of London; Regional Molecular Genetics Laboratory (N.T., R.H.S.), North East Thames Regional Genetics Service, and Department of Clinical Genetics (A.V.K., R.H.S.), Great Ormond Street Hospital, London, UK; Department of Paediatric Neurology (S.A.), Red Cross War Memorial Children's Hospital, Cape Town, South Africa; Department of Paediatric Neurology (G.A.), Addenbrooke's Hospital, Cambridge; Roald Dahl EEG Unit (R.A.), Department of Neurology, and Department of Neurology (R.K.), Alder Hey Children's Hospital, Liverpool; Department of Paediatric Neurology (A.D.), Sheffield Children's Hospital; Clinical Neurosciences (C.E., J.H.C.), Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health, London; Institute of Infection and Global Health (R.K.), University of Liverpool; Department of Paediatric Neurology (K.L.), Evelina Children's Hospital, Guys and St. Thomas' NHS Foundation Trust, London; Department of Clinical Genetics (T.M.), Northern Genetics Service; Department of Pediatric Neurology (V.R.), Great North Children's Hospital, Newcastle Upon Tyne; Department of Paediatric Neurology (R.S.), University Hospital Leicester Children's Hospital; Department of Paediatric Neurology (J.T.), Royal Manchester Children's Hospital; Department of Paediatric Neurology (W.W.), Nottingham University Hospitals NHS Trust, UK; Epilepsy Genetics Program (A. Poduri), Department of Neurology, Boston Children's Hospital; Department of Neurology (A. Poduri), Harvard Medical School, Boston, MA; University of Melbourne (I.E.S.), Austin Health and Royal Children's Hospital, Australia; and Department of Medicine (S.P.), Royal Melbourne Hospital, University of Melbourne, Australia. Dr. Malhotra is currently at the Department of Biochemistry, University of Cambridge, UK
| | - Manju A Kurian
- From Molecular Neurosciences (A.M., E.M., A., A.N., M.A.K.), Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health; Department of Neurology (A.M., A., A.N., C.E., J.H.C., M.A.K.) and Neuroradiology (W.K.C.), Great Ormond Street Hospital for Children, London, UK; Florey Institute of Neuroscience and Mental Health (U.N., E.V.G., I.E.S., S.P.), Melbourne, Australia; Department of Biological Sciences (S.M., M.T.), Institute of Structural and Molecular Biology, Birkbeck College, University of London; Regional Molecular Genetics Laboratory (N.T., R.H.S.), North East Thames Regional Genetics Service, and Department of Clinical Genetics (A.V.K., R.H.S.), Great Ormond Street Hospital, London, UK; Department of Paediatric Neurology (S.A.), Red Cross War Memorial Children's Hospital, Cape Town, South Africa; Department of Paediatric Neurology (G.A.), Addenbrooke's Hospital, Cambridge; Roald Dahl EEG Unit (R.A.), Department of Neurology, and Department of Neurology (R.K.), Alder Hey Children's Hospital, Liverpool; Department of Paediatric Neurology (A.D.), Sheffield Children's Hospital; Clinical Neurosciences (C.E., J.H.C.), Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health, London; Institute of Infection and Global Health (R.K.), University of Liverpool; Department of Paediatric Neurology (K.L.), Evelina Children's Hospital, Guys and St. Thomas' NHS Foundation Trust, London; Department of Clinical Genetics (T.M.), Northern Genetics Service; Department of Pediatric Neurology (V.R.), Great North Children's Hospital, Newcastle Upon Tyne; Department of Paediatric Neurology (R.S.), University Hospital Leicester Children's Hospital; Department of Paediatric Neurology (J.T.), Royal Manchester Children's Hospital; Department of Paediatric Neurology (W.W.), Nottingham University Hospitals NHS Trust, UK; Epilepsy Genetics Program (A. Poduri), Department of Neurology, Boston Children's Hospital; Department of Neurology (A. Poduri), Harvard Medical School, Boston, MA; University of Melbourne (I.E.S.), Austin Health and Royal Children's Hospital, Australia; and Department of Medicine (S.P.), Royal Melbourne Hospital, University of Melbourne, Australia. Dr. Malhotra is currently at the Department of Biochemistry, University of Cambridge, UK.
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HRPU-2, a Homolog of Mammalian hnRNP U, Regulates Synaptic Transmission by Controlling the Expression of SLO-2 Potassium Channel in Caenorhabditis elegans. J Neurosci 2017; 38:1073-1084. [PMID: 29217678 DOI: 10.1523/jneurosci.1991-17.2017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Revised: 11/27/2017] [Accepted: 12/02/2017] [Indexed: 12/22/2022] Open
Abstract
Slo2 channels are large-conductance potassium channels abundantly expressed in the nervous system. However, it is unclear how their expression level in neurons is regulated. Here we report that HRPU-2, an RNA-binding protein homologous to mammalian heterogeneous nuclear ribonucleoprotein U (hnRNP U), plays an important role in regulating the expression of SLO-2 (a homolog of mammalian Slo2) in Caenorhabditis elegans Loss-of-function (lf) mutants of hrpu-2 were isolated in a genetic screen for suppressors of a sluggish phenotype caused by a hyperactive SLO-2. In hrpu-2(lf) mutants, SLO-2-mediated delayed outward currents in neurons are greatly decreased, and neuromuscular synaptic transmission is enhanced. These mutant phenotypes can be rescued by expressing wild-type HRPU-2 in neurons. HRPU-2 binds to slo-2 mRNA, and hrpu-2(lf) mutants show decreased SLO-2 protein expression. In contrast, hrpu-2(lf) does not alter the expression of either the BK channel SLO-1 or the Shaker type potassium channel SHK-1. hrpu-2(lf) mutants are indistinguishable from wild type in gross motor neuron morphology and locomotion behavior. Together, these observations suggest that HRPU-2 plays important roles in SLO-2 function by regulating SLO-2 protein expression, and that SLO-2 is likely among a restricted set of proteins regulated by HRPU-2. Mutations of human Slo2 channel and hnRNP U are strongly linked to epileptic disorders and intellectual disability. The findings of this study suggest a potential link between these two molecules in human patients.SIGNIFICANCE STATEMENT Heterogeneous nuclear ribonucleoprotein U (hnRNP U) belongs to a family of RNA-binding proteins that play important roles in controlling gene expression. Recent studies have established a strong link between mutations of hnRNP U and human epilepsies and intellectual disability. However, it is unclear how mutations of hnRNP U may cause such disorders. This study shows that mutations of HRPU-2, a worm homolog of mammalian hnRNP U, result in dysfunction of a Slo2 potassium channel, which is critical to neuronal function. Because mutations of Slo2 channels are also strongly associated with epileptic encephalopathies and intellectual disability in humans, the findings of this study point to a potential mechanism underlying neurological disorders caused by hnRNP U mutations.
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The Slo(w) path to identifying the mitochondrial channels responsible for ischemic protection. Biochem J 2017; 474:2067-2094. [PMID: 28600454 DOI: 10.1042/bcj20160623] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Revised: 02/10/2017] [Accepted: 02/13/2017] [Indexed: 12/19/2022]
Abstract
Mitochondria play an important role in tissue ischemia and reperfusion (IR) injury, with energetic failure and the opening of the mitochondrial permeability transition pore being the major causes of IR-induced cell death. Thus, mitochondria are an appropriate focus for strategies to protect against IR injury. Two widely studied paradigms of IR protection, particularly in the field of cardiac IR, are ischemic preconditioning (IPC) and volatile anesthetic preconditioning (APC). While the molecular mechanisms recruited by these protective paradigms are not fully elucidated, a commonality is the involvement of mitochondrial K+ channel opening. In the case of IPC, research has focused on a mitochondrial ATP-sensitive K+ channel (mitoKATP), but, despite recent progress, the molecular identity of this channel remains a subject of contention. In the case of APC, early research suggested the existence of a mitochondrial large-conductance K+ (BK, big conductance of potassium) channel encoded by the Kcnma1 gene, although more recent work has shown that the channel that underlies APC is in fact encoded by Kcnt2 In this review, we discuss both the pharmacologic and genetic evidence for the existence and identity of mitochondrial K+ channels, and the role of these channels both in IR protection and in regulating normal mitochondrial function.
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The Phe932Ile mutation in KCNT1 channels associated with severe epilepsy, delayed myelination and leukoencephalopathy produces a loss-of-function channel phenotype. Neuroscience 2017; 351:65-70. [PMID: 28366665 DOI: 10.1016/j.neuroscience.2017.03.035] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Revised: 03/08/2017] [Accepted: 03/22/2017] [Indexed: 12/13/2022]
Abstract
Sodium-activated potassium (KNa) channels contribute to firing frequency adaptation and slow after hyperpolarization. The KCNT1 gene (also known as SLACK) encodes a KNa subunit that is expressed throughout the central and peripheral nervous systems. Missense mutations of the SLACK C-terminus have been reported in several patients with rare forms of early onset epilepsy and in some cases severely delayed myelination. To date, such mutations identified in patients with autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE), epilepsy of infancy with migrating focal seizures (EIMFS) and Ohtahara syndrome (OS) have been reported to be gain-of-function mutations (Villa and Combi, 2016). An exome sequencing study identified a p.Phe932Ile KCNT1 mutation as the disease-causing change in a child with severe early infantile epileptic encephalopathy and abnormal myelination (Vanderver et al., 2014). We characterized an analogous mutation in the rat Slack channel and unexpectedly found this mutation to produce a loss-of-function phenotype. In an effort to restore current, we tested the known Slack channel opener loxapine. Loxapine exhibited no effect, indicating that this mutation either caused the channel to be insensitive to this established opener or proper translation and trafficking to the membrane was disrupted. Protein analysis confirmed that while total mutant protein did not differ from wild type, membrane expression of the mutant channel was substantially reduced. Although gain-of-function mutations to the Slack channel are linked to epileptic phenotypes, this is the first reported loss-of-function mutation linked to severe epilepsy and delayed myelination.
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Tejada MA, Hashem N, Calloe K, Klaerke DA. Heteromeric Slick/Slack K+ channels show graded sensitivity to cell volume changes. PLoS One 2017; 12:e0169914. [PMID: 28222129 PMCID: PMC5319697 DOI: 10.1371/journal.pone.0169914] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Accepted: 12/22/2016] [Indexed: 12/16/2022] Open
Abstract
Slick and Slack high-conductance K+ channels are found in the CNS, kidneys, pancreas, among other organs, where they play an important role in cell excitability as well as in ion transport processes. They are both activated by Na+ and Cl- but show a differential regulation by cell volume changes. Slick has been shown to be regulated by cell volume changes, whereas Slack is insensitive. α-subunits of these channels form homomeric as well as heteromeric channels. It is the aim of this work to explore whether the subunit composition of the Slick/Slack heteromeric channel affects the response to osmotic challenges. In order to provide with the adequate water permeability to the cell membrane of Xenopus laevis oocytes, mRNA of aquaporin 1 was co-expressed with homomeric or heteromeric Slick and Slack α-subunits. Oocytes were superfused with hypotonic or hypertonic buffers and changes in currents were measured by two-electrode voltage clamp. This work presents the first heteromeric K+ channel with a characteristic graded sensitivity to small and fast changes in cell volume. Our results show that the cell volume sensitivity of Slick/Slack heteromeric channels is dependent on the number of volume sensitive Slick α-subunits in the tetrameric channels, giving rise to graded cell volume sensitivity. Regulation of the subunit composition of a channel may constitute a novel mechanism to determine volume sensitivity of cells.
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Affiliation(s)
- Maria A. Tejada
- Department of Physiology, IKVH, Faculty of Health and Medical Sciences, University of Copenhagen, Dyrlaegevej, Frederiksberg C, Denmark
| | - Nadia Hashem
- Department of Physiology, IKVH, Faculty of Health and Medical Sciences, University of Copenhagen, Dyrlaegevej, Frederiksberg C, Denmark
| | - Kirstine Calloe
- Department of Physiology, IKVH, Faculty of Health and Medical Sciences, University of Copenhagen, Dyrlaegevej, Frederiksberg C, Denmark
| | - Dan A. Klaerke
- Department of Physiology, IKVH, Faculty of Health and Medical Sciences, University of Copenhagen, Dyrlaegevej, Frederiksberg C, Denmark
- * E-mail:
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Kaczmarek LK, Aldrich RW, Chandy KG, Grissmer S, Wei AD, Wulff H. International Union of Basic and Clinical Pharmacology. C. Nomenclature and Properties of Calcium-Activated and Sodium-Activated Potassium Channels. Pharmacol Rev 2017; 69:1-11. [PMID: 28267675 PMCID: PMC11060434 DOI: 10.1124/pr.116.012864] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/02/2024] Open
Abstract
A subset of potassium channels is regulated primarily by changes in the cytoplasmic concentration of ions, including calcium, sodium, chloride, and protons. The eight members of this subfamily were originally all designated as calcium-activated channels. More recent studies have clarified the gating mechanisms for these channels and have documented that not all members are sensitive to calcium. This article describes the molecular relationships between these channels and provides an introduction to their functional properties. It also introduces a new nomenclature that differentiates between calcium- and sodium-activated potassium channels.
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Affiliation(s)
- Leonard K Kaczmarek
- Departments of Pharmacology and Cellular and Molecular Physiology, Yale School of Medicine, New Haven, Connecticut (L.K.K.); Center for Learning and Memory and Department of Neuroscience, University of Texas at Austin, Austin, Texas (R.W.A.); Laboratory of Molecular Physiology in the Infection and Immunity Theme, Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore (K.G.C.); Institute of Applied Physiology, Ulm University, Ulm, Germany (S.G.); Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington (A.D.W.); and Department of Pharmacology, School of Medicine, University of California, Davis, California (H.W.)
| | - Richard W Aldrich
- Departments of Pharmacology and Cellular and Molecular Physiology, Yale School of Medicine, New Haven, Connecticut (L.K.K.); Center for Learning and Memory and Department of Neuroscience, University of Texas at Austin, Austin, Texas (R.W.A.); Laboratory of Molecular Physiology in the Infection and Immunity Theme, Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore (K.G.C.); Institute of Applied Physiology, Ulm University, Ulm, Germany (S.G.); Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington (A.D.W.); and Department of Pharmacology, School of Medicine, University of California, Davis, California (H.W.)
| | - K George Chandy
- Departments of Pharmacology and Cellular and Molecular Physiology, Yale School of Medicine, New Haven, Connecticut (L.K.K.); Center for Learning and Memory and Department of Neuroscience, University of Texas at Austin, Austin, Texas (R.W.A.); Laboratory of Molecular Physiology in the Infection and Immunity Theme, Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore (K.G.C.); Institute of Applied Physiology, Ulm University, Ulm, Germany (S.G.); Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington (A.D.W.); and Department of Pharmacology, School of Medicine, University of California, Davis, California (H.W.)
| | - Stephan Grissmer
- Departments of Pharmacology and Cellular and Molecular Physiology, Yale School of Medicine, New Haven, Connecticut (L.K.K.); Center for Learning and Memory and Department of Neuroscience, University of Texas at Austin, Austin, Texas (R.W.A.); Laboratory of Molecular Physiology in the Infection and Immunity Theme, Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore (K.G.C.); Institute of Applied Physiology, Ulm University, Ulm, Germany (S.G.); Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington (A.D.W.); and Department of Pharmacology, School of Medicine, University of California, Davis, California (H.W.)
| | - Aguan D Wei
- Departments of Pharmacology and Cellular and Molecular Physiology, Yale School of Medicine, New Haven, Connecticut (L.K.K.); Center for Learning and Memory and Department of Neuroscience, University of Texas at Austin, Austin, Texas (R.W.A.); Laboratory of Molecular Physiology in the Infection and Immunity Theme, Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore (K.G.C.); Institute of Applied Physiology, Ulm University, Ulm, Germany (S.G.); Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington (A.D.W.); and Department of Pharmacology, School of Medicine, University of California, Davis, California (H.W.)
| | - Heike Wulff
- Departments of Pharmacology and Cellular and Molecular Physiology, Yale School of Medicine, New Haven, Connecticut (L.K.K.); Center for Learning and Memory and Department of Neuroscience, University of Texas at Austin, Austin, Texas (R.W.A.); Laboratory of Molecular Physiology in the Infection and Immunity Theme, Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore (K.G.C.); Institute of Applied Physiology, Ulm University, Ulm, Germany (S.G.); Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington (A.D.W.); and Department of Pharmacology, School of Medicine, University of California, Davis, California (H.W.)
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Cardiac Slo2.1 Is Required for Volatile Anesthetic Stimulation of K+ Transport and Anesthetic Preconditioning. Anesthesiology 2016; 124:1065-76. [PMID: 26845140 DOI: 10.1097/aln.0000000000001046] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
BACKGROUND Anesthetic preconditioning (APC) is a clinically important phenomenon in which volatile anesthetics (VAs) protect tissues such as heart against ischemic injury. The mechanism of APC is thought to involve K channels encoded by the Slo gene family, and the authors showed previously that slo-2 is required for APC in Caenorhabditis elegans. Thus, the authors hypothesized that a slo-2 ortholog may mediate APC-induced cardioprotection in mammals. METHODS A perfused heart model of ischemia-reperfusion injury, a fluorescent assay for K flux, and mice lacking Slo2.1 (Slick), Slo2.2 (Slack), or both (double knockouts, Slo2.x dKO) were used to test whether these channels are required for APC-induced cardioprotection and for cardiomyocyte or mitochondrial K transport. RESULTS In wild-type (WT) hearts, APC improved post-ischemia-reperfusion functional recovery (APC = 39.5 ± 3.7% of preischemic rate × pressure product vs. 20.3 ± 2.3% in controls, means ± SEM, P = 0.00051, unpaired two-tailed t test, n = 8) and lowered infarct size (APC = 29.0 ± 4.8% of LV area vs. 51.4 ± 4.5% in controls, P = 0.0043, n = 8). Protection by APC was absent in hearts from Slo2.1 mice (% recovery APC = 14.6 ± 2.6% vs. 16.5 ± 2.1% in controls, P = 0.569, n = 8 to 9, infarct APC = 52.2 ± 5.4% vs. 53.5 ± 4.7% in controls, P = 0.865, n = 8 to 9). APC protection was also absent in Slo2.x dKO hearts (% recovery APC = 11.0 ± 1.7% vs. 11.9 ± 2.2% in controls, P = 0.725, n = 8, infarct APC = 51.6 ± 4.4% vs. 50.5 ± 3.9% in controls, P = 0.855, n = 8). Meanwhile, Slo2.2 hearts responded similar to WT (% recovery APC = 41.9 ± 4.0% vs. 18.0 ± 2.5% in controls, P = 0.00016, n = 8, infarct APC = 25.2 ± 1.3% vs. 50.8 ± 3.3% in controls, P < 0.000005, n = 8). Furthermore, VA-stimulated K transport seen in cardiomyocytes or mitochondria from WT or Slo2.2 mice was absent in Slo2.1 or Slo2.x dKO. CONCLUSION Slick (Slo2.1) is required for both VA-stimulated K flux and for the APC-induced cardioprotection.
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Bansal V, Fisher TE. Na(+) -Activated K(+) Channels in Rat Supraoptic Neurones. J Neuroendocrinol 2016; 28. [PMID: 27091544 DOI: 10.1111/jne.12394] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/16/2016] [Revised: 04/06/2016] [Accepted: 04/15/2016] [Indexed: 11/29/2022]
Abstract
The magnocellular neurosecretory cells (MNCs) of the hypothalamus secrete the neurohormones vasopressin and oxytocin. The systemic release of these hormones depends on the rate and pattern of MNC firing and it is therefore important to identify the ion channels that contribute to the electrical behaviour of MNCs. In the present study, we report evidence for the presence of Na(+) -activated K(+) (KN a ) channels in rat MNCs. KN a channels mediate outwardly rectifying K(+) currents activated by the increases in intracellular Na(+) that occur during electrical activity. Although the molecular identity of native KN a channels is unclear, their biophysical properties are consistent with those of expressed Slick (slo 2.1) and Slack (slo 2.2) proteins. Using immunocytochemistry and Western blot experiments, we found that both Slick and Slack proteins are expressed in rat MNCs. Using whole cell voltage clamp techniques on acutely isolated rat MNCs, we found that inhibiting Na(+) influx by the addition of the Na(+) channel blocker tetrodotoxin or the replacement of Na(+) in the external solution with Li(+) caused a significant decrease in sustained outward currents. Furthermore, the evoked outward current density was significantly higher in rat MNCs using patch pipettes containing 60 mm Na(+) than it was when patch pipettes containing 0 mm Na(+) were used. Our data show that functional KN a channels are expressed in rat MNCs. These channels could contribute to the activity-dependent afterhyperpolarisations that have been identified in the MNCs and thereby play a role in the regulation of their electrical behaviour.
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Affiliation(s)
- V Bansal
- Department of Physiology, College of Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - T E Fisher
- Department of Physiology, College of Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
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Ohya S, Kito H, Hatano N, Muraki K. Recent advances in therapeutic strategies that focus on the regulation of ion channel expression. Pharmacol Ther 2016; 160:11-43. [PMID: 26896566 DOI: 10.1016/j.pharmthera.2016.02.001] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
A number of different ion channel types are involved in cell signaling networks, and homeostatic regulatory mechanisms contribute to the control of ion channel expression. Profiling of global gene expression using microarray technology has recently provided novel insights into the molecular mechanisms underlying the homeostatic and pathological control of ion channel expression. It has demonstrated that the dysregulation of ion channel expression is associated with the pathogenesis of neural, cardiovascular, and immune diseases as well as cancers. In addition to the transcriptional, translational, and post-translational regulation of ion channels, potentially important evidence on the mechanisms controlling ion channel expression has recently been accumulated. The regulation of alternative pre-mRNA splicing is therefore a novel therapeutic strategy for the treatment of dominant-negative splicing disorders. Epigenetic modification plays a key role in various pathological conditions through the regulation of pluripotency genes. Inhibitors of pre-mRNA splicing and histone deacetyalase/methyltransferase have potential as potent therapeutic drugs for cancers and autoimmune and inflammatory diseases. Moreover, membrane-anchoring proteins, lysosomal and proteasomal degradation-related molecules, auxiliary subunits, and pharmacological agents alter the protein folding, membrane trafficking, and post-translational modifications of ion channels, and are linked to expression-defect channelopathies. In this review, we focused on recent insights into the transcriptional, spliceosomal, epigenetic, and proteasomal regulation of ion channel expression: Ca(2+) channels (TRPC/TRPV/TRPM/TRPA/Orai), K(+) channels (voltage-gated, KV/Ca(2+)-activated, KCa/two-pore domain, K2P/inward-rectifier, Kir), and Ca(2+)-activated Cl(-) channels (TMEM16A/TMEM16B). Furthermore, this review highlights expression of these ion channels in expression-defect channelopathies.
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Affiliation(s)
- Susumu Ohya
- Department of Pharmacology, Division of Pathological Sciences, Kyoto Pharmaceutical University, Kyoto 607-8414, Japan.
| | - Hiroaki Kito
- Department of Pharmacology, Division of Pathological Sciences, Kyoto Pharmaceutical University, Kyoto 607-8414, Japan
| | - Noriyuki Hatano
- Laboratory of Cellular Pharmacology, School of Pharmacy, Aichi-Gakuin University, Nagoya 464-8650, Japan
| | - Katsuhiko Muraki
- Laboratory of Cellular Pharmacology, School of Pharmacy, Aichi-Gakuin University, Nagoya 464-8650, Japan.
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Lim CX, Ricos MG, Dibbens LM, Heron SE. KCNT1mutations in seizure disorders: the phenotypic spectrum and functional effects. J Med Genet 2016; 53:217-25. [DOI: 10.1136/jmedgenet-2015-103508] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2015] [Accepted: 12/06/2015] [Indexed: 01/01/2023]
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Rizzi S, Knaus HG, Schwarzer C. Differential distribution of the sodium-activated potassium channels slick and slack in mouse brain. J Comp Neurol 2015; 524:2093-116. [PMID: 26587966 PMCID: PMC4982087 DOI: 10.1002/cne.23934] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2015] [Revised: 11/10/2015] [Accepted: 11/11/2015] [Indexed: 12/11/2022]
Abstract
The sodium‐activated potassium channels Slick (Slo2.1, KCNT2) and Slack (Slo2.2, KCNT1) are high‐conductance potassium channels of the Slo family. In neurons, Slick and Slack channels are involved in the generation of slow afterhyperpolarization, in the regulation of firing patterns, and in setting and stabilizing the resting membrane potential. The distribution and subcellular localization of Slick and Slack channels in the mouse brain have not yet been established in detail. The present study addresses this issue through in situ hybridization and immunohistochemistry. Both channels were widely distributed and exhibited distinct distribution patterns. However, in some brain regions, their expression overlapped. Intense Slick channel immunoreactivity was observed in processes, varicosities, and neuronal cell bodies of the olfactory bulb, granular zones of cortical regions, hippocampus, amygdala, lateral septal nuclei, certain hypothalamic and midbrain nuclei, and several regions of the brainstem. The Slack channel showed primarily a diffuse immunostaining pattern, and labeling of cell somata and processes was observed only occasionally. The highest Slack channel expression was detected in the olfactory bulb, lateral septal nuclei, basal ganglia, and distinct areas of the midbrain, brainstem, and cerebellar cortex. In addition, comparing our data obtained from mouse brain with a previously published study on rat brain revealed some differences in the expression and distribution of Slick and Slack channels in these species. J. Comp. Neurol. 524:2093–2116, 2016. © 2015 The Authors The Journal of Comparative Neurology Published by Wiley Periodicals, Inc.
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Affiliation(s)
- Sandra Rizzi
- Division of Molecular and Cellular Pharmacology, Medical University of Innsbruck, 6020, Innsbruck, Austria
| | - Hans-Günther Knaus
- Division of Molecular and Cellular Pharmacology, Medical University of Innsbruck, 6020, Innsbruck, Austria
| | - Christoph Schwarzer
- Department of Pharmacology, Medical University of Innsbruck, 6020, Innsbruck, Austria
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Martinez-Espinosa PL, Wu J, Yang C, Gonzalez-Perez V, Zhou H, Liang H, Xia XM, Lingle CJ. Knockout of Slo2.2 enhances itch, abolishes KNa current, and increases action potential firing frequency in DRG neurons. eLife 2015; 4:e10013. [PMID: 26559620 PMCID: PMC4641468 DOI: 10.7554/elife.10013] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2015] [Accepted: 10/06/2015] [Indexed: 02/02/2023] Open
Abstract
Two mammalian genes, Kcnt1 and Kcnt2, encode pore-forming subunits of Na(+)-dependent K(+) (KNa) channels. Progress in understanding KNa channels has been hampered by the absence of specific tools and methods for rigorous KNa identification in native cells. Here, we report the genetic disruption of both Kcnt1 and Kcnt2, confirm the loss of Slo2.2 and Slo2.1 protein, respectively, in KO animals, and define tissues enriched in Slo2 expression. Noting the prevalence of Slo2.2 in dorsal root ganglion, we find that KO of Slo2.2, but not Slo2.1, results in enhanced itch and pain responses. In dissociated small diameter DRG neurons, KO of Slo2.2, but not Slo2.1, abolishes KNa current. Utilizing isolectin B4+ neurons, the absence of KNa current results in an increase in action potential (AP) firing and a decrease in AP threshold. Activation of KNa acts as a brake to initiation of the first depolarization-elicited AP with no discernible effect on afterhyperpolarizations.
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Affiliation(s)
| | - Jianping Wu
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, United States
| | - Chengtao Yang
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, United States
| | - Vivian Gonzalez-Perez
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, United States
| | - Huifang Zhou
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, United States
| | - Hongwu Liang
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, United States
| | - Xiao-Ming Xia
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, United States
| | - Christopher J Lingle
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, United States
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Identification of potential novel interaction partners of the sodium-activated potassium channels Slick and Slack in mouse brain. Biochem Biophys Rep 2015; 4:291-298. [PMID: 29124216 PMCID: PMC5669359 DOI: 10.1016/j.bbrep.2015.09.024] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Revised: 09/18/2015] [Accepted: 09/29/2015] [Indexed: 02/06/2023] Open
Abstract
The sodium-activated potassium channels Slick (Slo2.1, KCNT2) and Slack (Slo2.2, KCNT1) are paralogous channels of the Slo family of high-conductance potassium channels. Slick and Slack channels are widely distributed in the mammalian CNS and they play a role in slow afterhyperpolarization, generation of depolarizing afterpotentials and in setting and stabilizing the resting potential. In the present study we used a combined approach of (co)-immunoprecipitation studies, Western blot analysis, double immunofluorescence and mass spectrometric sequencing in order to investigate protein-protein interactions of the Slick and Slack channels. The data strongly suggest that Slick and Slack channels co-assemble into identical cellular complexes. Double immunofluorescence experiments revealed that Slick and Slack channels co-localize in distinct mouse brain regions. Moreover, we identified the small cytoplasmic protein beta-synuclein and the transmembrane protein 263 (TMEM 263) as novel interaction partners of both, native Slick and Slack channels. In addition, the inactive dipeptidyl-peptidase (DPP 10) and the synapse associated protein 102 (SAP 102) were identified as constituents of the native Slick and Slack channel complexes in the mouse brain. This study presents new insights into protein-protein interactions of native Slick and Slack channels in the mouse brain.
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Takahashi I, Yoshino M. Functional coupling between sodium-activated potassium channels and voltage-dependent persistent sodium currents in cricket Kenyon cells. J Neurophysiol 2015; 114:2450-9. [PMID: 26269549 DOI: 10.1152/jn.00087.2015] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Accepted: 08/09/2015] [Indexed: 01/02/2023] Open
Abstract
In this study, we examined the functional coupling between Na(+)-activated potassium (KNa) channels and Na(+) influx through voltage-dependent Na(+) channels in Kenyon cells isolated from the mushroom body of the cricket Gryllus bimaculatus. Single-channel activity of KNa channels was recorded with the cell-attached patch configuration. The open probability (Po) of KNa channels increased with increasing Na(+) concentration in a bath solution, whereas it decreased by the substitution of Na(+) with an equimolar concentration of Li(+). The Po of KNa channels was also found to be reduced by bath application of a high concentration of TTX (1 μM) and riluzole (100 μM), which inhibits both fast (INaf) and persistent (INaP) Na(+) currents, whereas it was unaffected by a low concentration of TTX (10 nM), which selectively blocks INaf. Bath application of Cd(2+) at a low concentration (50 μM), as an inhibitor of INaP, also decreased the Po of KNa channels. Conversely, bath application of the inorganic Ca(2+)-channel blockers Co(2+) and Ni(2+) at high concentrations (500 μM) had little effect on the Po of KNa channels, although Cd(2+) (500 μM) reduced the Po of KNa channels. Perforated whole cell clamp analysis further indicated the presence of sustained outward currents for which amplitude was dependent on the amount of Na(+) influx. Taken together, these results indicate that KNa channels could be activated by Na(+) influx passing through voltage-dependent persistent Na(+) channels. The functional significance of this coupling mechanism was discussed in relation to the membrane excitability of Kenyon cells and its possible role in the formation of long-term memory.
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Affiliation(s)
- Izumi Takahashi
- Department of Biology, Tokyo Gakugei University, Tokyo, Japan
| | - Masami Yoshino
- Department of Biology, Tokyo Gakugei University, Tokyo, Japan
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Steinmann ME, González-Salgado A, Bütikofer P, Mäser P, Sigel E. A heteromeric potassium channel involved in the modulation of the plasma membrane potential is essential for the survival of African trypanosomes. FASEB J 2015; 29:3228-37. [DOI: 10.1096/fj.15-271353] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Accepted: 03/31/2015] [Indexed: 11/11/2022]
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Abstract
Slack (Slo2.2) is a sodium-activated potassium channel that regulates neuronal firing activities and patterns. Previous studies identified Slack in sensory neurons, but its contribution to acute and chronic pain in vivo remains elusive. Here we generated global and sensory neuron-specific Slack mutant mice and analyzed their behavior in various animal models of pain. Global ablation of Slack led to increased hypersensitivity in models of neuropathic pain, whereas the behavior in models of inflammatory and acute nociceptive pain was normal. Neuropathic pain behaviors were also exaggerated after ablation of Slack selectively in sensory neurons. Notably, the Slack opener loxapine ameliorated persisting neuropathic pain behaviors. In conclusion, Slack selectively controls the sensory input in neuropathic pain states, suggesting that modulating its activity might represent a novel strategy for management of neuropathic pain.
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Kim GE, Kronengold J, Barcia G, Quraishi IH, Martin HC, Blair E, Taylor JC, Dulac O, Colleaux L, Nabbout R, Kaczmarek LK. Human slack potassium channel mutations increase positive cooperativity between individual channels. Cell Rep 2014; 9:1661-1672. [PMID: 25482562 DOI: 10.1016/j.celrep.2014.11.015] [Citation(s) in RCA: 86] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2014] [Revised: 10/06/2014] [Accepted: 11/10/2014] [Indexed: 11/24/2022] Open
Abstract
Disease-causing mutations in ion channels generally alter intrinsic gating properties such as activation, inactivation, and voltage dependence. We examined nine different mutations of the KCNT1 (Slack) Na(+)-activated K(+) channel that give rise to three distinct forms of epilepsy. All produced many-fold increases in current amplitude compared to the wild-type channel. This could not be accounted for by increases in the intrinsic open probability of individual channels. Rather, greatly increased opening was a consequence of cooperative interactions between multiple channels in a patch. The degree of cooperative gating was much greater for all of the mutant channels than for the wild-type channel, and could explain increases in current even in a mutant with reduced unitary conductance. We also found that the same mutation gave rise to different forms of epilepsy in different individuals. Our findings indicate that a major consequence of these mutations is to alter channel-channel interactions.
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Affiliation(s)
- Grace E Kim
- Department of Pharmacology, Yale University, New Haven, CT 06520, USA; Department of Cellular and Molecular Physiology, Yale University, New Haven, CT 06520, USA
| | - Jack Kronengold
- Department of Pharmacology, Yale University, New Haven, CT 06520, USA
| | - Giulia Barcia
- Department of Pediatric Neurology, Centre de Reference Epilepsies Rares, Hôpital Necker-Enfants Malades, Assistance Publique-Hôpitaux de Paris, 75015 Paris, France
| | - Imran H Quraishi
- Comprehensive Epilepsy Center, Department of Neurology, Yale University, New Haven, CT 06520, USA
| | - Hilary C Martin
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
| | - Edward Blair
- Oxford University Hospitals Trust, Oxford OX3 9DU, UK
| | - Jenny C Taylor
- Oxford Biomedical Research Centre, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
| | - Olivier Dulac
- Department of Pediatric Neurology, Centre de Reference Epilepsies Rares, Hôpital Necker-Enfants Malades, Assistance Publique-Hôpitaux de Paris, 75015 Paris, France
| | - Laurence Colleaux
- INSERM U781, Université Paris Descartes, Sorbonne Paris Cité, Institut Imagine, Hôpital Necker-Enfants Malades, 75015 Paris, France
| | - Rima Nabbout
- Department of Pediatric Neurology, Centre de Reference Epilepsies Rares, Hôpital Necker-Enfants Malades, Assistance Publique-Hôpitaux de Paris, 75015 Paris, France
| | - Leonard K Kaczmarek
- Department of Pharmacology, Yale University, New Haven, CT 06520, USA; Department of Cellular and Molecular Physiology, Yale University, New Haven, CT 06520, USA.
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Cell volume changes regulate slick (Slo2.1), but not slack (Slo2.2) K+ channels. PLoS One 2014; 9:e110833. [PMID: 25347289 PMCID: PMC4210196 DOI: 10.1371/journal.pone.0110833] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2014] [Accepted: 09/05/2014] [Indexed: 01/10/2023] Open
Abstract
Slick (Slo2.1) and Slack (Slo2.2) channels belong to the family of high-conductance K+ channels and have been found widely distributed in the CNS. Both channels are activated by Na+ and Cl− and, in addition, Slick channels are regulated by ATP. Therefore, the roles of these channels in regulation of cell excitability as well as ion transport processes, like regulation of cell volume, have been hypothesized. It is the aim of this work to evaluate the sensitivity of Slick and Slack channels to small, fast changes in cell volume and to explore mechanisms, which may explain this type of regulation. For this purpose Slick and Slack channels were co-expressed with aquaporin 1 in Xenopus laevis oocytes and cell volume changes of around 5% were induced by exposure to hypotonic or hypertonic media. Whole-cell currents were measured by two electrode voltage clamp. Our results show that Slick channels are dramatically stimulated (196% of control) by cell swelling and inhibited (57% of control) by a decrease in cell volume. In contrast, Slack channels are totally insensitive to similar cell volume changes. The mechanism underlining the strong volume sensitivity of Slick channels needs to be further explored, however we were able to show that it does not depend on an intact actin cytoskeleton, ATP release or vesicle fusion. In conclusion, Slick channels, in contrast to the similar Slack channels, are the only high-conductance K+ channels strongly sensitive to small changes in cell volume.
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Kim GE, Kaczmarek LK. Emerging role of the KCNT1 Slack channel in intellectual disability. Front Cell Neurosci 2014; 8:209. [PMID: 25120433 PMCID: PMC4112808 DOI: 10.3389/fncel.2014.00209] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2014] [Accepted: 07/10/2014] [Indexed: 01/15/2023] Open
Abstract
The sodium-activated potassium KNa channels Slack and Slick are encoded by KCNT1 and KCNT2, respectively. These channels are found in neurons throughout the brain, and are responsible for a delayed outward current termed I KNa. These currents integrate into shaping neuronal excitability, as well as adaptation in response to maintained stimulation. Abnormal Slack channel activity may play a role in Fragile X syndrome, the most common cause for intellectual disability and inherited autism. Slack channels interact directly with the fragile X mental retardation protein (FMRP) and I KNa is reduced in animal models of Fragile X syndrome that lack FMRP. Human Slack mutations that alter channel activity can also lead to intellectual disability, as has been found for several childhood epileptic disorders. Ongoing research is elucidating the relationship between mutant Slack channel activity, development of early onset epilepsies and intellectual impairment. This review describes the emerging role of Slack channels in intellectual disability, coupled with an overview of the physiological role of neuronal I KNa currents.
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Affiliation(s)
- Grace E Kim
- Departments of Pharmacology and Cellular & Molecular Physiology, Yale University School of Medicine New Haven, CT, USA
| | - Leonard K Kaczmarek
- Departments of Pharmacology and Cellular & Molecular Physiology, Yale University School of Medicine New Haven, CT, USA
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González C, Baez-Nieto D, Valencia I, Oyarzún I, Rojas P, Naranjo D, Latorre R. K(+) channels: function-structural overview. Compr Physiol 2013; 2:2087-149. [PMID: 23723034 DOI: 10.1002/cphy.c110047] [Citation(s) in RCA: 143] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Potassium channels are particularly important in determining the shape and duration of the action potential, controlling the membrane potential, modulating hormone secretion, epithelial function and, in the case of those K(+) channels activated by Ca(2+), damping excitatory signals. The multiplicity of roles played by K(+) channels is only possible to their mammoth diversity that includes at present 70 K(+) channels encoding genes in mammals. Today, thanks to the use of cloning, mutagenesis, and the more recent structural studies using x-ray crystallography, we are in a unique position to understand the origins of the enormous diversity of this superfamily of ion channels, the roles they play in different cell types, and the relations that exist between structure and function. With the exception of two-pore K(+) channels that are dimers, voltage-dependent K(+) channels are tetrameric assemblies and share an extremely well conserved pore region, in which the ion-selectivity filter resides. In the present overview, we discuss in the function, localization, and the relations between function and structure of the five different subfamilies of K(+) channels: (a) inward rectifiers, Kir; (b) four transmembrane segments-2 pores, K2P; (c) voltage-gated, Kv; (d) the Slo family; and (e) Ca(2+)-activated SK family, SKCa.
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Affiliation(s)
- Carlos González
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
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Abstract
The Slack and Slick genes encode potassium channels that are very widely expressed in the central nervous system. These channels are activated by elevations in intracellular sodium, such as those that occur during trains of one or more action potentials, or following activation of non-selective cationic neurotransmitter receptors such as AMPA receptors. This review covers the cellular and molecular properties of Slack and Slick channels and compares them with findings on the properties of sodium-activated potassium currents (termed KNa currents) in native neurons. Human mutations in Slack channels produce extremely severe defects in learning and development, suggesting that KNa channels play a central role in neuronal plasticity and intellectual function.
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49
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Regulation of neuronal excitability by interaction of fragile X mental retardation protein with slack potassium channels. J Neurosci 2013; 32:15318-27. [PMID: 23115170 DOI: 10.1523/jneurosci.2162-12.2012] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Loss of the RNA-binding protein fragile X mental retardation protein (FMRP) represents the most common form of inherited intellectual disability. Studies with heterologous expression systems indicate that FMRP interacts directly with Slack Na(+)-activated K(+) channels (K(Na)), producing an enhancement of channel activity. We have now used Aplysia bag cell (BC) neurons, which regulate reproductive behaviors, to examine the effects of Slack and FMRP on excitability. FMRP and Slack immunoreactivity were colocalized at the periphery of isolated BC neurons, and the two proteins could be reciprocally coimmunoprecipitated. Intracellular injection of FMRP lacking its mRNA binding domain rapidly induced a biphasic outward current, with an early transient tetrodotoxin-sensitive component followed by a slowly activating sustained component. The properties of this current matched that of the native Slack potassium current, which was identified using an siRNA approach. Addition of FMRP to inside-out patches containing native Aplysia Slack channels increased channel opening and, in current-clamp recordings, produced narrowing of action potentials. Suppression of Slack expression did not alter the ability of BC neurons to undergo a characteristic prolonged discharge in response to synaptic stimulation, but prevented recovery from a prolonged inhibitory period that normally follows the discharge. Recovery from the inhibited period was also inhibited by the protein synthesis inhibitor anisomycin. Our studies indicate that, in BC neurons, Slack channels are required for prolonged changes in neuronal excitability that require new protein synthesis, and raise the possibility that channel-FMRP interactions may link changes in neuronal firing to changes in protein translation.
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Liu J, Bukiya AN, Kuntamallappanavar G, Singh AK, Dopico AM. Distinct sensitivity of slo1 channel proteins to ethanol. Mol Pharmacol 2012; 83:235-44. [PMID: 23093494 DOI: 10.1124/mol.112.081240] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Ethanol levels reached in circulation during moderate-to-heavy alcohol intoxication (50-100 mM) modify Ca(2+)- and voltage-gated K(+) (BK) channel steady-state activity, eventually altering both physiology and behavior. Ethanol action on BK steady-state activity solely requires the channel-forming subunit slo1 within a bare lipid environment. To identify the protein regions that confer ethanol sensitivity to slo1, we tested the ethanol sensitivity of heterologously expressed slo1 and structurally related channels. Ethanol (50 mM) increased the steady-state activities of mslo1 and Ca(2+)-gated MthK, the latter after channel reconstitution into phospholipid bilayers. In contrast, 50-100 mM ethanol failed to alter the steady-state activities of Na(+)/Cl(-)-gated rslo2, H(+)-gated mslo3, and an mslo1/3 chimera engineered by joining the mslo1 region encompassing the N terminus to S6 with the mslo3 cytosolic tail domain (CTD). Collectively, data indicate that the slo family canonical design, which combines a transmembrane 6 (TM6) voltage-gated K(+) channel (K(V)) core with CTDs that empower the channel with ion-sensing, does not necessarily render ethanol sensitivity. In addition, the region encompassing the N terminus to the S0-S1 cytosolic loop (missing in MthK) is not necessary for ethanol action. Moreover, incorporation of both this region and an ion-sensing CTD to TM6 K(V) cores (a design common to mslo1, mslo3, and the mslo1/mslo3 chimera) is not sufficient for ethanol sensitivity. Rather, a CTD containing Ca(2+)-sensing regulator of conductance for K(+) domains seems to be critical to bestow K(V) structures, whether of TM2 (MthK) or TM6 (slo1), with sensitivity to intoxicating ethanol levels.
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Affiliation(s)
- Jianxi Liu
- University of Tennessee Health Science Center, College of Medicine, Department of Pharmacology, 874 Union Avenue, Memphis, TN 38163, USA
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