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Jędrychowska J, Vardanyan V, Wieczor M, Marciniak A, Czub J, Amini R, Jain R, Shen H, Choi H, Kuznicki J, Korzh V. Mutant analysis of Kcng4b reveals how the different functional states of the voltage-gated potassium channel regulate ear development. Dev Biol 2024; 513:50-62. [PMID: 38492873 DOI: 10.1016/j.ydbio.2024.03.002] [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: 08/01/2023] [Revised: 03/04/2024] [Accepted: 03/06/2024] [Indexed: 03/18/2024]
Abstract
The voltage gated (Kv) slow-inactivating delayed rectifier channel regulates the development of hollow organs of the zebrafish. The functional channel consists of the tetramer of electrically active Kcnb1 (Kv2.1) subunits and Kcng4b (Kv6.4) modulatory or electrically silent subunits. The two mutations in zebrafish kcng4b gene - kcng4b-C1 and kcng4b-C2 (Gasanov et al., 2021) - have been studied during ear development using electrophysiology, developmental biology and in silico structural modelling. kcng4b-C1 mutation causes a C-terminal truncation characterized by mild Kcng4b loss-of-function (LOF) manifested by failure of kinocilia to extend and formation of ectopic otoliths. In contrast, the kcng4b-C2-/- mutation causes the C-terminal domain to elongate and the ectopic seventh transmembrane (TM) domain to form, converting the intracellular C-terminus to an extracellular one. Kcng4b-C2 acts as a Kcng4b gain-of-function (GOF) allele. Otoliths fail to develop and kinocilia are reduced in kcng4b-C2-/-. These results show that different mutations of the silent subunit Kcng4 can affect the activity of the Kv channel and cause a wide range of developmental defects.
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Affiliation(s)
- Justyna Jędrychowska
- International Institute of Molecular and Cell Biology in Warsaw, Poland; Department of Genetics, Institute of Physiology and Pathology of Hearing, Warsaw, Poland
| | - Vitya Vardanyan
- Institute of Molecular Biology, Armenian Academy of Sciences, Yerevan, Armenia
| | - Milosz Wieczor
- Department of Physical Chemistry, Gdansk University of Technology, Gdansk, Poland
| | - Antoni Marciniak
- Department of Physical Chemistry, Gdansk University of Technology, Gdansk, Poland
| | - Jacek Czub
- Department of Physical Chemistry, Gdansk University of Technology, Gdansk, Poland
| | - Razieh Amini
- International Institute of Molecular and Cell Biology in Warsaw, Poland
| | - Ruchi Jain
- International Institute of Molecular and Cell Biology in Warsaw, Poland
| | - Hongyuan Shen
- Singapore Nuclear Research and Safety Initiative, National University of Singapore, Singapore
| | - Hyungwon Choi
- Cardiovascular Research Institute, National University Health Sciences, Singapore; Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Jacek Kuznicki
- International Institute of Molecular and Cell Biology in Warsaw, Poland
| | - Vladimir Korzh
- International Institute of Molecular and Cell Biology in Warsaw, Poland.
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2
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Singh V, Auerbach DS. Neurocardiac pathologies associated with potassium channelopathies. Epilepsia 2024. [PMID: 39087855 DOI: 10.1111/epi.18066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2024] [Revised: 07/10/2024] [Accepted: 07/10/2024] [Indexed: 08/02/2024]
Abstract
Voltage-gated potassium channels are expressed throughout the human body and are essential for physiological functions. These include delayed rectifiers, A-type channels, outward rectifiers, and inward rectifiers. They impact electrical function in the heart (repolarization) and brain (repolarization and stabilization of the resting membrane potential). KCNQx and KCNHx encode Kv7.x and Kv11.x proteins, which form delayed rectifier potassium channels. KCNQx and KCNHx channelopathies are associated with both cardiac and neuronal pathologies. These include electrocardiographic abnormalities, cardiac arrhythmias, sudden cardiac death (SCD), epileptiform discharges, seizures, bipolar disorder, and sudden unexpected death in epilepsy (SUDEP). Due to the ubiquitous expression of KCNQx and KCNHx channels, abnormalities in their function can be particularly harmful, increasing the risk of sudden death. For example, KCNH2 variants have a dual role in both cardiac and neuronal pathologies, whereas KCNQ2 and KCNQ3 variants are associated with severe and refractory epilepsy. Recurrent and uncontrolled seizures lead to secondary abnormalities, which include autonomics, cardiac electrical function, respiratory drive, and neuronal electrical activity. Even with a wide array of anti-seizure therapies available on the market, one-third of the more than 70 million people worldwide with epilepsy have uncontrolled seizures (i.e., intractable/drug-resistant epilepsy), which negatively impact neurodevelopment and quality of life. To capture the current state of the field, this review examines KCNQx and KCNHx expression patterns and electrical function in the brain and heart. In addition, it discusses several KCNQx and KCNHx variants that have been clinically and electrophysiologically characterized. Because these channel variants are associated with multi-system pathologies, such as epileptogenesis, Kv7 channel modulators provide a potential anti-seizure therapy, particularly for people with intractable epilepsy. Ultimately an increased understanding of the role of Kv channels throughout the body will fuel the development of innovative, safe, and effective therapies for people at a high risk of sudden death (SCD and SUDEP).
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Affiliation(s)
- Veronica Singh
- Department of Pharmacology, SUNY Upstate Medical University, Syracuse, New York, USA
| | - David S Auerbach
- Department of Pharmacology, SUNY Upstate Medical University, Syracuse, New York, USA
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Shin HJ, Ko A, Kim SH, Lee JS, Kang HC. Unusual Voltage-Gated Sodium and Potassium Channelopathies Related to Epilepsy. J Clin Neurol 2024; 20:402-411. [PMID: 38951973 PMCID: PMC11220354 DOI: 10.3988/jcn.2023.0435] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Revised: 01/03/2024] [Accepted: 01/23/2024] [Indexed: 07/03/2024] Open
Abstract
BACKGROUND AND PURPOSE There is extensive literature on monogenic epilepsies caused by mutations in familiar channelopathy genes such as SCN1A. However, information on other less-common channelopathy genes is scarce. This study aimed to explore the genetic and clinical characteristics of patients diagnosed with unusual voltage-gated sodium and potassium channelopathies related to epilepsy. METHODS This observational, retrospective study analyzed pediatric patients with epilepsy who carried pathogenic variants of unusual voltage-gated sodium and potassium channelopathy genes responsible for seizure-associated phenotypes. Targeted next-generation sequencing (NGS) panel tests were performed between November 2016 and June 2022 at Severance Children's Hospital, Seoul, South Korea. Clinical characteristics and the treatment responses to different types of antiseizure medications were further analyzed according to different types of gene mutation. RESULTS This study included 15 patients with the following unusual voltage-gated sodium and potassium channelopathy genes: SCN3A (n=1), SCN4A (n=1), KCNA1 (n=1), KCNA2 (n=4), KCNB1 (n=6), KCNC1 (n=1), and KCNMA1 (n=1). NGS-based genetic testing identified 13 missense mutations (87%), 1 splice-site variant (7%), and 1 copy-number variant (7%). Developmental and epileptic encephalopathy was diagnosed in nine (60%) patients. Seizure freedom was eventually achieved in eight (53%) patients, whereas seizures persisted in seven (47%) patients. CONCLUSIONS Our findings broaden the genotypic and phenotypic spectra of less-common voltage-gated sodium and potassium channelopathies associated with epilepsy.
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Affiliation(s)
- Hui Jin Shin
- Division of Pediatric Neurology, Department of Pediatrics, Severance Children's Hospital, Yonsei University College of Medicine, Seoul, Korea
| | - Ara Ko
- Division of Pediatric Neurology, Department of Pediatrics, Severance Children's Hospital, Yonsei University College of Medicine, Seoul, Korea
| | - Se Hee Kim
- Division of Pediatric Neurology, Department of Pediatrics, Severance Children's Hospital, Yonsei University College of Medicine, Seoul, Korea
| | - Joon Soo Lee
- Division of Pediatric Neurology, Department of Pediatrics, Severance Children's Hospital, Yonsei University College of Medicine, Seoul, Korea
| | - Hoon-Chul Kang
- Division of Pediatric Neurology, Department of Pediatrics, Severance Children's Hospital, Yonsei University College of Medicine, Seoul, Korea.
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Zhao T, Wang L, Chen F. Potassium channel-related epilepsy: Pathogenesis and clinical features. Epilepsia Open 2024; 9:891-905. [PMID: 38560778 PMCID: PMC11145612 DOI: 10.1002/epi4.12934] [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: 04/25/2023] [Revised: 03/11/2024] [Accepted: 03/17/2024] [Indexed: 04/04/2024] Open
Abstract
Variants in potassium channel-related genes are one of the most important mechanisms underlying abnormal neuronal excitation and disturbances in the cellular resting membrane potential. These variants can cause different forms of epilepsy, which can seriously affect the physical and mental health of patients, especially those with refractory epilepsy or status epilepticus, which are common among pediatric patients and are potentially life-threatening. Variants in potassium ion channel-related genes have been reported in few studies; however, to our knowledge, no systematic review has been published. This study aimed to summarize the epilepsy phenotypes, functional studies, and pharmacological advances associated with different potassium channel gene variants to assist clinical practitioners and drug development teams to develop evidence-based medicine and guide research strategies. PubMed and Google Scholar were searched for relevant literature on potassium channel-related epilepsy reported in the past 5-10 years. Various common potassium ion channel gene variants can lead to heterogeneous epilepsy phenotypes, and functional effects can result from gene deletions and compound effects. Administration of select anti-seizure medications is the primary treatment for this type of epilepsy. Most patients are refractory to anti-seizure medications, and some novel anti-seizure medications have been found to improve seizures. Use of targeted drugs to correct aberrant channel function based on the type of potassium channel gene variant can be used as an evidence-based pathway to achieve precise and individualized treatment for children with epilepsy. PLAIN LANGUAGE SUMMARY: In this article, the pathogenesis and clinical characteristics of epilepsy caused by different types of potassium channel gene variants are reviewed in the light of the latest research literature at home and abroad, with the expectation of providing a certain theoretical basis for the diagnosis and treatment of children with this type of disease.
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Affiliation(s)
- Tong Zhao
- Hebei Children's HospitalShijiazhuangHebeiChina
| | - Le Wang
- Hebei Children's HospitalShijiazhuangHebeiChina
| | - Fang Chen
- Hebei Children's HospitalShijiazhuangHebeiChina
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5
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Qunies AM, Spitznagel BD, Du Y, Peprah PK, Mohamed YK, Weaver CD, Emmitte KA. Structure-Activity Relationship Studies in a Series of Xanthine Inhibitors of SLACK Potassium Channels. Molecules 2024; 29:2437. [PMID: 38893312 PMCID: PMC11173529 DOI: 10.3390/molecules29112437] [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: 04/30/2024] [Revised: 05/17/2024] [Accepted: 05/20/2024] [Indexed: 06/21/2024] Open
Abstract
Gain-of-function mutations in the KCNT1 gene, which encodes the sodium-activated potassium channel known as SLACK, are associated with the rare but devastating developmental and epileptic encephalopathy known as epilepsy of infancy with migrating focal seizures (EIMFS). The design of small molecule inhibitors of SLACK channels represents a potential therapeutic approach to the treatment of EIMFS, other childhood epilepsies, and developmental disorders. Herein, we describe a hit optimization effort centered on a xanthine SLACK inhibitor (8) discovered via a high-throughput screen. Across three distinct regions of the chemotype, we synthesized 58 new analogs and tested each one in a whole-cell automated patch-clamp assay to develop structure-activity relationships for inhibition of SLACK channels. We further evaluated selected analogs for their selectivity versus a variety of other ion channels and for their activity versus clinically relevant SLACK mutants. Selectivity within the series was quite good, including versus hERG. Analog 80 (VU0948578) was a potent inhibitor of WT, A934T, and G288S SLACK, with IC50 values between 0.59 and 0.71 µM across these variants. VU0948578 represents a useful in vitro tool compound from a chemotype that is distinct from previously reported small molecule inhibitors of SLACK channels.
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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 for Chemical Biology, Vanderbilt University, Nashville, TN 37232, USA
| | - Paul K. Peprah
- 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
| | - Yasmeen K. Mohamed
- Department of Pharmaceutical Sciences, UNT System College of Pharmacy, University of North Texas Health Science Center, Fort Worth, TX 76107, USA
| | - C. David Weaver
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA
- Vanderbilt Institute for 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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Delgado-Ramírez M, López-Serrano AL, Rodríguez-Menchaca AA. Inhibition of Kv2.1 potassium channels by the antidepressant drug sertraline. Eur J Pharmacol 2024; 970:176487. [PMID: 38458411 DOI: 10.1016/j.ejphar.2024.176487] [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: 12/15/2023] [Revised: 02/07/2024] [Accepted: 03/05/2024] [Indexed: 03/10/2024]
Abstract
Sertraline is a commonly used antidepressant of the selective serotonin reuptake inhibitors (SSRIs) class. In this study, we have used the patch-clamp technique to assess the effects of sertraline on Kv2.1 channels heterologously expressed in HEK-293 cells and on the voltage-gated potassium currents (IKv) of Neuro 2a cells, which are predominantly mediated by Kv2.1 channels. Our results reveal that sertraline inhibits Kv2.1 channels in a concentration-dependent manner. The sertraline-induced inhibition was not voltage-dependent and did not require the channels to be open. The kinetics of activation and deactivation were accelerated and decelerated, respectively, by sertraline. Moreover, the inhibition by this drug was use-dependent. Notably, sertraline significantly modified the inactivation mechanism of Kv2.1 channels; the steady-state inactivation was shifted to hyperpolarized potentials, the closed-state inactivation was enhanced and accelerated, and the recovery from inactivation was slowed, suggesting that this is the main mechanism by which sertraline inhibits Kv2.1 channels. Overall, this study provides novel insights into the pharmacological actions of sertraline on Kv2.1 channels, shedding light on the intricate interaction between SSRIs and ion channel function.
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Affiliation(s)
- Mayra Delgado-Ramírez
- Departamento de Fisiología y Biofísica, Facultad de Medicina, Universidad Autónoma de San Luis Potosí, San Luis Potosí, SLP, 78210, Mexico.
| | - Ana Laura López-Serrano
- Departamento de Fisiología y Biofísica, Facultad de Medicina, Universidad Autónoma de San Luis Potosí, San Luis Potosí, SLP, 78210, Mexico
| | - Aldo A Rodríguez-Menchaca
- Departamento de Fisiología y Biofísica, Facultad de Medicina, Universidad Autónoma de San Luis Potosí, San Luis Potosí, SLP, 78210, Mexico
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7
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Wang Y, Yang J. ER-organelle contacts: A signaling hub for neurological diseases. Pharmacol Res 2024; 203:107149. [PMID: 38518830 DOI: 10.1016/j.phrs.2024.107149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/28/2023] [Revised: 03/07/2024] [Accepted: 03/19/2024] [Indexed: 03/24/2024]
Abstract
Neuronal health is closely linked to the homeostasis of intracellular organelles, and organelle dysfunction affects the pathological progression of neurological diseases. In contrast to isolated cellular compartments, a growing number of studies have found that organelles are largely interdependent structures capable of communicating through membrane contact sites (MCSs). MCSs have been identified as key pathways mediating inter-organelle communication crosstalk in neurons, and their alterations have been linked to neurological disease pathology. The endoplasmic reticulum (ER) is a membrane-bound organelle capable of forming an extensive network of pools and tubules with important physiological functions within neurons. There are multiple MCSs between the ER and other organelles and the plasma membrane (PM), which regulate a variety of cellular processes. In this review, we focus on ER-organelle MCSs and their role in a variety of neurological diseases. We compared the biological effects between different tethering proteins and the effects of their respective disease counterparts. We also discuss how altered ER-organelle contacts may affect disease pathogenesis. Therefore, understanding the molecular mechanisms of ER-organelle MCSs in neuronal homeostasis will lay the foundation for the development of new therapies targeting ER-organelle contacts.
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Affiliation(s)
- Yunli Wang
- Key Laboratory of Environmental Stress and Chronic Disease Control & Prevention (China Medical University), Ministry of Education, PR China; Department of Toxicology, School of Public Health, China Medical University, Shenyang 110122, PR China
| | - Jinghua Yang
- Key Laboratory of Environmental Stress and Chronic Disease Control & Prevention (China Medical University), Ministry of Education, PR China; Department of Toxicology, School of Public Health, China Medical University, Shenyang 110122, PR China.
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8
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Kang SK, Hawkins NA, Thompson CH, Baker EM, Echevarria-Cooper DM, Barse L, Thenstedt T, Dixon CJ, Speakes N, George AL, Kearney JA. Altered neurological and neurobehavioral phenotypes in a mouse model of the recurrent KCNB1-p.R306C voltage-sensor variant. Neurobiol Dis 2024; 194:106470. [PMID: 38485094 PMCID: PMC11024897 DOI: 10.1016/j.nbd.2024.106470] [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: 03/29/2023] [Revised: 02/23/2024] [Accepted: 03/06/2024] [Indexed: 03/21/2024] Open
Abstract
Pathogenic variants in KCNB1 are associated with a neurodevelopmental disorder spectrum that includes global developmental delays, cognitive impairment, abnormal electroencephalogram (EEG) patterns, and epilepsy with variable age of onset and severity. Additionally, there are prominent behavioral disturbances, including hyperactivity, aggression, and features of autism spectrum disorder. The most frequently identified recurrent variant is KCNB1-p.R306C, a missense variant located within the S4 voltage-sensing transmembrane domain. Individuals with the R306C variant exhibit mild to severe developmental delays, behavioral disorders, and a diverse spectrum of seizures. Previous in vitro characterization of R306C described altered sensitivity and cooperativity of the voltage sensor and impaired capacity for repetitive firing of neurons. Existing Kcnb1 mouse models include dominant negative missense variants, as well as knockout and frameshifts alleles. While all models recapitulate key features of KCNB1 encephalopathy, mice with dominant negative alleles were more severely affected. In contrast to existing loss-of-function and dominant-negative variants, KCNB1-p.R306C does not affect channel expression, but rather affects voltage-sensing. Thus, modeling R306C in mice provides a novel opportunity to explore impacts of a voltage-sensing mutation in Kcnb1. Using CRISPR/Cas9 genome editing, we generated the Kcnb1R306C mouse model and characterized the molecular and phenotypic effects. Consistent with the in vitro studies, neurons from Kcnb1R306C mice showed altered excitability. Heterozygous and homozygous R306C mice exhibited hyperactivity, altered susceptibility to chemoconvulsant-induced seizures, and frequent, long runs of slow spike wave discharges on EEG, reminiscent of the slow spike and wave activity characteristic of Lennox Gastaut syndrome. This novel model of channel dysfunction in Kcnb1 provides an additional, valuable tool to study KCNB1 encephalopathies. Furthermore, this allelic series of Kcnb1 mouse models will provide a unique platform to evaluate targeted therapies.
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Affiliation(s)
- Seok Kyu Kang
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA; Northwestern University Interdepartmental Neuroscience Program, Northwestern University, Chicago, IL 60611, USA
| | - Nicole A Hawkins
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Christopher H Thompson
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Erin M Baker
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Dennis M Echevarria-Cooper
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA; Northwestern University Interdepartmental Neuroscience Program, Northwestern University, Chicago, IL 60611, USA
| | - Levi Barse
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Tyler Thenstedt
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Conor J Dixon
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Nathan Speakes
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Alfred L George
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA; Northwestern University Interdepartmental Neuroscience Program, Northwestern University, Chicago, IL 60611, USA
| | - Jennifer A Kearney
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA; Northwestern University Interdepartmental Neuroscience Program, Northwestern University, Chicago, IL 60611, USA.
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9
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Bhat S, Rousseau J, Michaud C, Lourenço CM, Stoler JM, Louie RJ, Clarkson LK, Lichty A, Koboldt DC, Reshmi SC, Sisodiya SM, Hoytema van Konijnenburg EMM, Koop K, van Hasselt PM, Démurger F, Dubourg C, Sullivan BR, Hughes SS, Thiffault I, Tremblay ES, Accogli A, Srour M, Blunck R, Campeau PM. Mono-allelic KCNB2 variants lead to a neurodevelopmental syndrome caused by altered channel inactivation. Am J Hum Genet 2024; 111:761-777. [PMID: 38503299 PMCID: PMC11023922 DOI: 10.1016/j.ajhg.2024.02.014] [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: 07/28/2023] [Revised: 02/23/2024] [Accepted: 02/25/2024] [Indexed: 03/21/2024] Open
Abstract
Ion channels mediate voltage fluxes or action potentials that are central to the functioning of excitable cells such as neurons. The KCNB family of voltage-gated potassium channels (Kv) consists of two members (KCNB1 and KCNB2) encoded by KCNB1 and KCNB2, respectively. These channels are major contributors to delayed rectifier potassium currents arising from the neuronal soma which modulate overall excitability of neurons. In this study, we identified several mono-allelic pathogenic missense variants in KCNB2, in individuals with a neurodevelopmental syndrome with epilepsy and autism in some individuals. Recurrent dysmorphisms included a broad forehead, synophrys, and digital anomalies. Additionally, we selected three variants where genetic transmission has not been assessed, from two epilepsy studies, for inclusion in our experiments. We characterized channel properties of these variants by expressing them in oocytes of Xenopus laevis and conducting cut-open oocyte voltage clamp electrophysiology. Our datasets indicate no significant change in absolute conductance and conductance-voltage relationships of most disease variants as compared to wild type (WT), when expressed either alone or co-expressed with WT-KCNB2. However, variants c.1141A>G (p.Thr381Ala) and c.641C>T (p.Thr214Met) show complete abrogation of currents when expressed alone with the former exhibiting a left shift in activation midpoint when expressed alone or with WT-KCNB2. The variants we studied, nevertheless, show collective features of increased inactivation shifted to hyperpolarized potentials. We suggest that the effects of the variants on channel inactivation result in hyper-excitability of neurons, which contributes to disease manifestations.
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Affiliation(s)
- Shreyas Bhat
- Center for Interdisciplinary Research on Brain and Learning (CIRCA), Department of Physics and Department of Pharmacology and Physiology, Université de Montréal, Montréal, QC, Canada
| | - Justine Rousseau
- Centre de Recherche Du Centre Hospitalier Universitaire Sainte-Justine, Université de Montréal, Montréal, QC H3T 1C5, Canada
| | - Coralie Michaud
- Centre de Recherche Du Centre Hospitalier Universitaire Sainte-Justine, Université de Montréal, Montréal, QC H3T 1C5, Canada
| | | | - Joan M Stoler
- Division of Genetics and Genomics, Boston Children's Hospital, Boston, MA, USA
| | | | | | - Angie Lichty
- Greenwood Genetic Center, Greenwood, SC 29646, USA
| | - Daniel C Koboldt
- Steve and Cindy Rasmussen Institute for Genomic Medicine at Nationwide Children's Hospital, Columbus, OH, USA
| | - Shalini C Reshmi
- Steve and Cindy Rasmussen Institute for Genomic Medicine at Nationwide Children's Hospital, Columbus, OH, USA; Department of Pathology and Laboratory Medicine, Nationwide Children's Hospital, Columbus, OH, USA
| | - Sanjay M Sisodiya
- Department of Clinical and Experimental Epilepsy, University College London Queen Square Institute of Neurology, London WC1N 3BG, UK
| | | | - Klaas Koop
- Department of Metabolic Diseases, Wilhelmina Children's Hospital, University Medical Center Utrecht, Utrecht, the Netherlands
| | - Peter M van Hasselt
- Department of Genetics, Section Metabolic Diagnostics, University Medical Center Utrecht, Utrecht, the Netherlands
| | | | - Christèle Dubourg
- Department of Molecular Genetics and Genomics, Rennes University Hospital, Rennes, France; Université de Rennes, CNRS, IGDR, UMR 6290 Rennes, France
| | - Bonnie R Sullivan
- Division of Clinical Genetics, Department of Pediatrics, Children's Mercy Kansas City, Kansas City, MO, USA
| | - Susan S Hughes
- Division of Clinical Genetics, Department of Pediatrics, Children's Mercy Kansas City, Kansas City, MO, USA
| | - Isabelle Thiffault
- Departments of Pediatrics and of Pathology and Laboratory Medicine, Children's Mercy Kansas City, Kansas City, MO, USA
| | - Elisabeth Simard Tremblay
- Department of Neurology and Neurosurgery, McGill University Health Centre, Montréal, QC, Canada; Department of Pediatrics, Division of Pediatric Neurology, McGill University, Montréal, QC, Canada
| | - Andrea Accogli
- Department of Specialized Medicine, Division of Medical Genetics, McGill University Health Centre, Montréal, QC, Canada; Department of Human Genetics, Faculty of Medicine, McGill University, Montral, QC H3A 1B1, Canada
| | - Myriam Srour
- Department of Pediatrics, Division of Pediatric Neurology, McGill University, Montréal, QC, Canada; Department of Human Genetics, Faculty of Medicine, McGill University, Montral, QC H3A 1B1, Canada
| | - Rikard Blunck
- Center for Interdisciplinary Research on Brain and Learning (CIRCA), Department of Physics and Department of Pharmacology and Physiology, Université de Montréal, Montréal, QC, Canada.
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10
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Khan R, Chaturvedi P, Sahu P, Ludhiadch A, Singh P, Singh G, Munshi A. Role of Potassium Ion Channels in Epilepsy: Focus on Current Therapeutic Strategies. CNS & NEUROLOGICAL DISORDERS DRUG TARGETS 2024; 23:67-87. [PMID: 36578258 DOI: 10.2174/1871527322666221227112621] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Revised: 11/10/2022] [Accepted: 11/12/2022] [Indexed: 12/30/2022]
Abstract
BACKGROUND Epilepsy is one of the prevalent neurological disorders characterized by disrupted synchronization between inhibitory and excitatory neurons. Disturbed membrane potential due to abnormal regulation of neurotransmitters and ion transport across the neural cell membrane significantly contributes to the pathophysiology of epilepsy. Potassium ion channels (KCN) regulate the resting membrane potential and are involved in neuronal excitability. Genetic alterations in the potassium ion channels (KCN) have been reported to result in the enhancement of the release of neurotransmitters, the excitability of neurons, and abnormal rapid firing rate, which lead to epileptic phenotypes, making these ion channels a potential therapeutic target for epilepsy. The aim of this study is to explore the variations reported in different classes of potassium ion channels (KCN) in epilepsy patients, their functional evaluation, and therapeutic strategies to treat epilepsy targeting KCN. METHODOLOGY A review of all the relevant literature was carried out to compile this article. RESULTS A large number of variations have been reported in different genes encoding various classes of KCN. These genetic alterations in KCN have been shown to be responsible for disrupted firing properties of neurons. Antiepileptic drugs (AEDs) are the main therapeutic strategy to treat epilepsy. Some patients do not respond favorably to the AEDs treatment, resulting in pharmacoresistant epilepsy. CONCLUSION Further to address the challenges faced in treating epilepsy, recent approaches like optogenetics, chemogenetics, and genome editing, such as clustered regularly interspaced short palindromic repeats (CRISPR), are emerging as target-specific therapeutic strategies.
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Affiliation(s)
- Rahul Khan
- Department of Human Genetics and Molecular Medicine Central University of Punjab, Bathinda 151401, India
| | - Pragya Chaturvedi
- Department of Human Genetics and Molecular Medicine Central University of Punjab, Bathinda 151401, India
| | - Prachi Sahu
- Department of Human Genetics and Molecular Medicine Central University of Punjab, Bathinda 151401, India
| | - Abhilash Ludhiadch
- Department of Human Genetics and Molecular Medicine Central University of Punjab, Bathinda 151401, India
| | - Paramdeep Singh
- Department of Radiology, All India Institute of Medical Sciences, Bathinda, Punjab, 151001 India
| | - Gagandeep Singh
- Department of Neurology, Dayanand Medical College and Hospital, Ludhiana, Punjab, India
| | - Anjana Munshi
- Department of Human Genetics and Molecular Medicine Central University of Punjab, Bathinda 151401, India
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11
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Alam KA, Svalastoga P, Martinez A, Glennon JC, Haavik J. Potassium channels in behavioral brain disorders. Molecular mechanisms and therapeutic potential: A narrative review. Neurosci Biobehav Rev 2023; 152:105301. [PMID: 37414376 DOI: 10.1016/j.neubiorev.2023.105301] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 06/26/2023] [Accepted: 06/30/2023] [Indexed: 07/08/2023]
Abstract
Potassium channels (K+-channels) selectively control the passive flow of potassium ions across biological membranes and thereby also regulate membrane excitability. Genetic variants affecting many of the human K+-channels are well known causes of Mendelian disorders within cardiology, neurology, and endocrinology. K+-channels are also primary targets of many natural toxins from poisonous organisms and drugs used within cardiology and metabolism. As genetic tools are improving and larger clinical samples are being investigated, the spectrum of clinical phenotypes implicated in K+-channels dysfunction is rapidly expanding, notably within immunology, neurosciences, and metabolism. K+-channels that previously were considered to be expressed in only a few organs and to have discrete physiological functions, have recently been found in multiple tissues and with new, unexpected functions. The pleiotropic functions and patterns of expression of K+-channels may provide additional therapeutic opportunities, along with new emerging challenges from off-target effects. Here we review the functions and therapeutic potential of K+-channels, with an emphasis on the nervous system, roles in neuropsychiatric disorders and their involvement in other organ systems and diseases.
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Affiliation(s)
| | - Pernille Svalastoga
- Mohn Center for Diabetes Precision Medicine, Department of Clinical Science, University of Bergen, Bergen, Norway; Children and Youth Clinic, Haukeland University Hospital, Bergen, Norway
| | | | - Jeffrey Colm Glennon
- Conway Institute for Biomolecular and Biomedical Research, School of Medicine, University College Dublin, Dublin, Ireland.
| | - Jan Haavik
- Department of Biomedicine, University of Bergen, Norway; Division of Psychiatry, Haukeland University Hospital, Norway.
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12
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Kang SK, Hawkins NA, Echevarria-Cooper DM, Baker EM, Dixon CJ, Speakes N, Kearney JA. Altered neurological and neurobehavioral phenotypes in a mouse model of the recurrent KCNB1-p.R306C voltage-sensor variant. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.29.534736. [PMID: 37034689 PMCID: PMC10081335 DOI: 10.1101/2023.03.29.534736] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
Pathogenic variants in KCNB1 are associated with a neurodevelopmental disorder spectrum that includes global developmental delays, cognitive impairment, abnormal electroencephalogram (EEG) patterns, and epilepsy with variable age of onset and severity. Additionally, there are prominent behavioral disturbances, including hyperactivity, aggression, and features of autism spectrum disorder. The most frequently identified recurrent variant is KCNB1-p.R306C, a missense variant located within the S4 voltage-sensing transmembrane domain. Individuals with the R306C variant exhibit mild to severe developmental delays, behavioral disorders, and a diverse spectrum of seizures. Previous in vitro characterization of R306C described loss of voltage sensitivity and cooperativity of the sensor and inhibition of repetitive firing. Existing Kcnb1 mouse models include dominant negative missense variants, as well as knockout and frameshifts alleles. While all models recapitulate key features of KCNB1 encephalopathy, mice with dominant negative alleles were more severely affected. In contrast to existing loss-of-function and dominant-negative variants, KCNB1-p.R306C does not affect channel expression, but rather affects voltage-sensing. Thus, modeling R306C in mice provides a novel opportunity to explore impacts of a voltage-sensing mutation in Kcnb1. Using CRISPR/Cas9 genome editing, we generated the Kcnb1R306C mouse model and characterized the molecular and phenotypic effects. Heterozygous and homozygous R306C mice exhibited pronounced hyperactivity, altered susceptibility to flurothyl and kainic acid induced-seizures, and frequent, long runs of spike wave discharges on EEG. This novel model of channel dysfunction in Kcnb1 provides an additional, valuable tool to study KCNB1 encephalopathies. Furthermore, this allelic series of Kcnb1 mouse models will provide a unique platform to evaluate targeted therapies.
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Affiliation(s)
- Seok Kyu Kang
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
- Northwestern University Interdepartmental Neuroscience Program, Northwestern University, Chicago, IL 60611, USA
| | - Nicole A Hawkins
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Dennis M Echevarria-Cooper
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
- Northwestern University Interdepartmental Neuroscience Program, Northwestern University, Chicago, IL 60611, USA
| | - Erin M Baker
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Conor J Dixon
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Nathan Speakes
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Jennifer A Kearney
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
- Northwestern University Interdepartmental Neuroscience Program, Northwestern University, Chicago, IL 60611, USA
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13
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Hiraide T, Akita T, Uematsu K, Miyamoto S, Nakashima M, Sasaki M, Fukuda A, Kato M, Saitsu H. A novel de novo KCNB1 variant altering channel characteristics in a patient with periventricular heterotopia, abnormal corpus callosum, and mild seizure outcome. J Hum Genet 2023; 68:25-31. [PMID: 36257979 DOI: 10.1038/s10038-022-01090-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Revised: 08/31/2022] [Accepted: 10/01/2022] [Indexed: 01/20/2023]
Abstract
KCNB1 encodes the α-subunit of Kv2.1, the main contributor to neuronal delayed rectifier potassium currents. The subunit consists of six transmembrane α helices (S1-S6), comprising the voltage-sensing domain (S1-S4) and the pore domain (S5-P-S6). Heterozygous KCNB1 pathogenic variants are associated with developmental and epileptic encephalopathy. Here we report an individual who shows the milder phenotype compared to the previously reported cases, including delayed language development, mild intellectual disability, attention deficit hyperactivity disorder, late-onset epilepsy responsive to an antiepileptic drug, elevation of serum creatine kinase, and peripheral axonal neuropathy. On the other hand, his brain MRI showed characteristic findings including periventricular heterotopia, polymicrogyria, and abnormal corpus callosum. Exome sequencing identified a novel de novo KCNB1 variant c.574G>A, p.(Ala192Thr) located in the S1 segment of the voltage-sensing domain. Functional analysis using the whole-cell patch-clamp technique in Neuro2a cells showed that the Ala192Thr mutant reduces both activation and inactivation of the channel at membrane voltages in the range of -50 to -30 mV. Our case could expand the phenotypic spectrum of patients with KCNB1 variants, and suggested that variants located in the S1 segment might be associated with a milder outcome of seizures.
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Affiliation(s)
- Takuya Hiraide
- Department of Biochemistry, Hamamatsu University School of Medicine, Hamamatsu, Japan.,Department of Pediatrics, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Tenpei Akita
- Department of Neurophysiology, Hamamatsu University School of Medicine, Hamamatsu, Japan. .,Division of Health Science, Department of Basic Nursing, Hamamatsu University School of Medicine, Hamamatsu, Japan.
| | - Kenji Uematsu
- Department of Child Neurology, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Sachiko Miyamoto
- Department of Biochemistry, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Mitsuko Nakashima
- Department of Biochemistry, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Masayuki Sasaki
- Department of Child Neurology, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Atsuo Fukuda
- Department of Neurophysiology, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Mitsuhiro Kato
- Department of Pediatrics, Showa University School of Medicine, Tokyo, Japan
| | - Hirotomo Saitsu
- Department of Biochemistry, Hamamatsu University School of Medicine, Hamamatsu, Japan.
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14
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Veale EL, Golluscio A, Grand K, Graham JM, Mathie A. A KCNB1 gain of function variant causes developmental delay and speech apraxia but not seizures. Front Pharmacol 2022; 13:1093313. [PMID: 36618935 PMCID: PMC9810754 DOI: 10.3389/fphar.2022.1093313] [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: 11/08/2022] [Accepted: 12/09/2022] [Indexed: 12/24/2022] Open
Abstract
Objective: Numerous pathogenic variants in KCNB1, which encodes the voltage-gated potassium channel, KV2.1, are linked to developmental and epileptic encephalopathies and associated with loss-of-function, -regulation, and -expression of the channel. Here we describe a novel de novo variant (P17T) occurring in the KV2.1 channel that is associated with a gain-of-function (GoF), with altered steady-state inactivation and reduced sensitivity to the selective toxin, guanxitoxin-1E and is clinically associated with neurodevelopmental disorders, without seizures. Methods: The autosomal dominant variant was identified using whole exome sequencing (WES). The functional effects of the KCNB1 variant on the encoded KV2.1 channel were investigated using whole-cell patch-clamp recordings. Results: We identified a de novo missense variant in the coding region of the KCNB1 gene, c.49C>A which encodes a p.P17T mutation in the N-terminus of the voltage-gated, KV2.1 potassium channel. Electrophysiological studies measuring the impact of the variant on the functional properties of the channel, identified a gain of current, rightward shifts in the steady-state inactivation curve and reduced sensitivity to the blocker, guanxitoxin-1E. Interpretation: The clinical evaluation of this KCNB1 mutation describes a novel variant that is associated with global developmental delays, mild hypotonia and joint laxity, but without seizures. Most of the phenotypic features described are reported for other variants of the KCNB1 gene. However, the absence of early-onset epileptic disorders is a much less common occurrence. This lack of seizure activity may be because other variants reported have resulted in loss-of-function of the encoded KV2.1 potassium channel, whereas this variant causes a gain-of-function.
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Affiliation(s)
- Emma L. Veale
- Medway School of Pharmacy, University of Kent and University of Greenwich, Chatham Maritime, United Kingdom
| | - Alessia Golluscio
- Medway School of Pharmacy, University of Kent and University of Greenwich, Chatham Maritime, United Kingdom
| | - Katheryn Grand
- Department of Pediatrics, Harbor-UCLA Medical Center, Cedars-Sinai Medical Center, David Geffen School of Medicine at UCLA, Los Angeles, CA, United States
| | - John M. Graham
- Department of Pediatrics, Harbor-UCLA Medical Center, Cedars-Sinai Medical Center, David Geffen School of Medicine at UCLA, Los Angeles, CA, United States,*Correspondence: Alistair Mathie, ; John M. Graham Jr.,
| | - Alistair Mathie
- Medway School of Pharmacy, University of Kent and University of Greenwich, Chatham Maritime, United Kingdom,School of Engineering, Arts, Science and Technology, University of Suffolk, Ipswich, United Kingdom,*Correspondence: Alistair Mathie, ; John M. Graham Jr.,
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15
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Sinha AS, Wang T, Watanabe M, Hosoi Y, Sohara E, Akita T, Uchida S, Fukuda A. WNK3 kinase maintains neuronal excitability by reducing inwardly rectifying K+ conductance in layer V pyramidal neurons of mouse medial prefrontal cortex. Front Mol Neurosci 2022; 15:856262. [PMID: 36311015 PMCID: PMC9613442 DOI: 10.3389/fnmol.2022.856262] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Accepted: 09/22/2022] [Indexed: 11/13/2022] Open
Abstract
The with-no-lysine (WNK) family of serine-threonine kinases and its downstream kinases of STE20/SPS1-related proline/alanine-rich kinase (SPAK) and oxidative stress-responsive kinase-1 (OSR1) may regulate intracellular Cl− homeostasis through phosphorylation of cation-Cl− co-transporters. WNK3 is expressed in fetal and postnatal brains, and its expression level increases during development. Its roles in neurons, however, remain uncertain. Using WNK3 knockout (KO) mice, we investigated the role of WNK3 in the regulation of the intracellular Cl− concentration ([Cl−]i) and the excitability of layer V pyramidal neurons in the medial prefrontal cortex (mPFC). Gramicidin-perforated patch-clamp recordings in neurons from acute slice preparation at the postnatal day 21 indicated a significantly depolarized reversal potential for GABAA receptor-mediated currents by 6 mV, corresponding to the higher [Cl−]i level by ~4 mM in KO mice than in wild-type littermates. However, phosphorylation levels of SPAK and OSR1 and those of neuronal Na+-K+-2Cl− co-transporter NKCC1 and K+-Cl− co-transporter KCC2 did not significantly differ between KO and wild-type mice. Meanwhile, the resting membrane potential of neurons was more hyperpolarized by 7 mV, and the minimum stimulus current necessary for firing induction was increased in KO mice. These were due to an increased inwardly rectifying K+ (IRK) conductance, mediated by classical inwardly rectifying (Kir) channels, in KO neurons. The introduction of an active form of WNK3 into the recording neurons reversed these changes. The potential role of KCC2 function in the observed changes of KO neurons was investigated by applying a selective KCC2 activator, CLP290. This reversed the enhanced IRK conductance in KO neurons, indicating that both WNK3 and KCC2 are intimately linked in the regulation of resting K+ conductance. Evaluation of synaptic properties revealed that the frequency of miniature excitatory postsynaptic currents (mEPSCs) was reduced, whereas that of inhibitory currents (mIPSCs) was slightly increased in KO neurons. Together, the impact of these developmental changes on the membrane and synaptic properties was manifested as behavioral deficits in pre-pulse inhibition, a measure of sensorimotor gating involving multiple brain regions including the mPFC, in KO mice. Thus, the basal function of WNK3 would be the maintenance and/or development of both intrinsic and synaptic excitabilities.
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Affiliation(s)
- Adya Saran Sinha
- Department of Neurophysiology, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Tianying Wang
- Department of Neurophysiology, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Miho Watanabe
- Department of Neurophysiology, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Yasushi Hosoi
- Department of Neurophysiology, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Eisei Sohara
- Department of Nephrology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan
| | - Tenpei Akita
- Department of Neurophysiology, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Shinichi Uchida
- Department of Nephrology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan
| | - Atsuo Fukuda
- Department of Neurophysiology, Hamamatsu University School of Medicine, Hamamatsu, Japan
- *Correspondence: Atsuo Fukuda
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16
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Kim S, Coukos R, Gao F, Krainc D. Dysregulation of organelle membrane contact sites in neurological diseases. Neuron 2022; 110:2386-2408. [PMID: 35561676 PMCID: PMC9357093 DOI: 10.1016/j.neuron.2022.04.020] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Revised: 03/21/2022] [Accepted: 04/18/2022] [Indexed: 10/18/2022]
Abstract
The defining evolutionary feature of eukaryotic cells is the emergence of membrane-bound organelles. Compartmentalization allows each organelle to maintain a spatially, physically, and chemically distinct environment, which greatly bolsters individual organelle function. However, the activities of each organelle must be balanced and are interdependent for cellular homeostasis. Therefore, properly regulated interactions between organelles, either physically or functionally, remain critical for overall cellular health and behavior. In particular, neuronal homeostasis depends heavily on the proper regulation of organelle function and cross talk, and deficits in these functions are frequently associated with diseases. In this review, we examine the emerging role of organelle contacts in neurological diseases and discuss how the disruption of contacts contributes to disease pathogenesis. Understanding the molecular mechanisms underlying the formation and regulation of organelle contacts will broaden our knowledge of their role in health and disease, laying the groundwork for the development of new therapies targeting interorganelle cross talk and function.
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Affiliation(s)
- Soojin Kim
- Department of Neurology, Northwestern University Feinberg School of Medicine, 303 E Chicago Avenue, Chicago, IL, 60611, USA
| | - Robert Coukos
- Department of Neurology, Northwestern University Feinberg School of Medicine, 303 E Chicago Avenue, Chicago, IL, 60611, USA
| | - Fanding Gao
- Department of Neurology, Northwestern University Feinberg School of Medicine, 303 E Chicago Avenue, Chicago, IL, 60611, USA
| | - Dimitri Krainc
- Department of Neurology, Northwestern University Feinberg School of Medicine, 303 E Chicago Avenue, Chicago, IL 60611, USA.
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17
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Xiong J, Liu Z, Chen S, Kessi M, Chen B, Duan H, Deng X, Yang L, Peng J, Yin F. Correlation Analyses of Clinical Manifestations and Variant Effects in KCNB1-Related Neurodevelopmental Disorder. Front Pediatr 2022; 9:755344. [PMID: 35071126 PMCID: PMC8767024 DOI: 10.3389/fped.2021.755344] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/08/2021] [Accepted: 12/14/2021] [Indexed: 12/24/2022] Open
Abstract
Objective: Vitro functional analyses of KCNB1 variants have been done to disclose possible pathogenic mechanisms in KCNB1-related neurodevelopmental disorder. "Complete or partial loss of function (LoF)," "dominant-negative (DN) effect" are applied to describe KCNB1 variant's molecular phenotypes. The study here aimed to investigate clinical presentations and variant effects associations in the disorder. Methods: We reported 10 Chinese pediatric patients with KCNB1-related neurodevelopmental disorder here. Functional experiments on newly reported variants, including electrophysiology and protein expression, were performed in vitro. Phenotypic, functional, and genetic data in the cohort and published literature were collected. According to their variants' molecular phenotypes, patients were grouped into complete or partial LoF, and DN effect or non-dominant-negative (non-DN) effect to compare their clinical features. Results: Nine causative KCNB1 variants in 10 patients were identified in the cohort, including eight novel and one reported. Epilepsy (9/10), global developmental delay (10/10), and behavior issues (7/10) were common clinical features in our patients. Functional analyses of 8 novel variants indicated three partial and five complete LoF variants, five DN and three non-DN effect variants. Patient 1 in our series with truncated variants, whose functional results supported haploinsufficiency, had the best prognosis. Cases in complete LoF group had earlier seizure onset age (64.3 vs. 16.7%, p = 0.01) and worse seizure outcomes (18.8 vs. 66.7%, p = 0.03), and patients in DN effect subgroup had multiple seizure types compared to those in non-DN effect subgroup (65.5 vs. 30.8%, p = 0.039). Conclusion: Patients with KCNB1 variants in the Asian cohort have similar clinical manifestations to those of other races. Truncated KCNB1 variants exhibiting with haploinsufficiency molecular phenotype are linked to milder phenotypes. Individuals with complete LoF and DN effect KCNB1 variants have more severe seizure attacks than the other two subgroups.
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Affiliation(s)
- Juan Xiong
- Department of Pediatrics, Xiangya Hospital, Central South University, Changsha, China
- Hunan Intellectual and Developmental Disabilities Research Center, Changsha, China
| | - Zhonghua Liu
- The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, China
| | - Shimeng Chen
- Department of Pediatrics, Xiangya Hospital, Central South University, Changsha, China
- Hunan Intellectual and Developmental Disabilities Research Center, Changsha, China
| | - Miriam Kessi
- Department of Pediatrics, Xiangya Hospital, Central South University, Changsha, China
- Hunan Intellectual and Developmental Disabilities Research Center, Changsha, China
| | - Baiyu Chen
- Department of Pediatrics, Xiangya Hospital, Central South University, Changsha, China
- Hunan Intellectual and Developmental Disabilities Research Center, Changsha, China
| | - Haolin Duan
- Department of Pediatrics, Xiangya Hospital, Central South University, Changsha, China
- Hunan Intellectual and Developmental Disabilities Research Center, Changsha, China
| | - Xiaolu Deng
- 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
| | - Jing Peng
- 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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18
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Hoshino H, Miya F, Kato M, Kanemura H. Efficacy of ethosuximide on atonic seizures with KCNB1 mutation. Pediatr Int 2022; 64:e14871. [PMID: 35099827 DOI: 10.1111/ped.14871] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Revised: 03/26/2021] [Accepted: 05/28/2021] [Indexed: 11/30/2022]
Affiliation(s)
- Hiroki Hoshino
- Department of Pediatrics, Toho University, Sakura, Chiba, Japan
| | - Fuyuki Miya
- Department of Medical Science Mathematics, Medical Research Institute, Tokyo Medical and Dental University, Bunkyo, Tokyo, Japan.,Laboratory for Medical Science Mathematics, RIKEN Center for integrative Medical Sciences, Yokohama, Kanagawa, Japan.,Laboratoty for Medical Science Mathematics, Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo, Tokyo, Japan
| | - Mitsuhiro Kato
- Department of Pediatrics, Showa University School of Medicine, Shinagawa, Tokyo, Japan
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19
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Yang YS, Choi JH, Rah JC. Hypoxia with inflammation and reperfusion alters membrane resistance by dynamically regulating voltage-gated potassium channels in hippocampal CA1 neurons. Mol Brain 2021; 14:147. [PMID: 34556177 PMCID: PMC8461870 DOI: 10.1186/s13041-021-00857-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Accepted: 09/07/2021] [Indexed: 02/01/2023] Open
Abstract
Hypoxia typically accompanies acute inflammatory responses in patients and animal models. However, a limited number of studies have examined the effect of hypoxia in combination with inflammation (Hypo-Inf) on neural function. We previously reported that neuronal excitability in hippocampal CA1 neurons decreased during hypoxia and greatly rebounded upon reoxygenation. We attributed this altered excitability mainly to the dynamic regulation of hyperpolarization-activated cyclic nucleotide-gated cation (HCN) channels and input resistance. However, the molecular mechanisms underlying input resistance changes by Hypo-Inf and reperfusion remained unclear. In the present study, we found that a change in the density of the delayed rectifier potassium current (IDR) can explain the input resistance variability. Furthermore, voltage-dependent inactivation of A-type potassium (IA) channels shifted in the depolarizing direction during Hypo-Inf and reverted to normal upon reperfusion without a significant alteration in the maximum current density. Our results indicate that changes in the input resistance, and consequently excitability, caused by Hypo-Inf and reperfusion are at least partially regulated by the availability and voltage dependence of KV channels. Moreover, these results suggest that selective KV channel modulators can be used as potential neuroprotective drugs to minimize hypoxia- and reperfusion-induced neuronal damage.
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Affiliation(s)
- Yoon-Sil Yang
- Korea Brain Research Institute, 61 Cheomdan-ro, Dong-gu, Daegu, 41062 South Korea
| | - Joon Ho Choi
- Korea Brain Research Institute, 61 Cheomdan-ro, Dong-gu, Daegu, 41062 South Korea
| | - Jong-Cheol Rah
- Korea Brain Research Institute, 61 Cheomdan-ro, Dong-gu, Daegu, 41062 South Korea
- Department of Brain & Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology, 333 Techno Jungang-daero, Dalseong-gun, Daegu, 42988 South Korea
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20
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Newkirk GS, Guan D, Dembrow N, Armstrong WE, Foehring RC, Spain WJ. Kv2.1 Potassium Channels Regulate Repetitive Burst Firing in Extratelencephalic Neocortical Pyramidal Neurons. Cereb Cortex 2021; 32:1055-1076. [PMID: 34435615 DOI: 10.1093/cercor/bhab266] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Revised: 07/01/2021] [Accepted: 07/03/2021] [Indexed: 11/14/2022] Open
Abstract
Coincidence detection and cortical rhythmicity are both greatly influenced by neurons' propensity to fire bursts of action potentials. In the neocortex, repetitive burst firing can also initiate abnormal neocortical rhythmicity (including epilepsy). Bursts are generated by inward currents that underlie a fast afterdepolarization (fADP) but less is known about outward currents that regulate bursting. We tested whether Kv2 channels regulate the fADP and burst firing in labeled layer 5 PNs from motor cortex of the Thy1-h mouse. Kv2 block with guangxitoxin-1E (GTx) converted single spike responses evoked by dendritic stimulation into multispike bursts riding on an enhanced fADP. Immunohistochemistry revealed that Thy1-h PNs expressed Kv2.1 (not Kv2.2) channels perisomatically (not in the dendrites). In somatic macropatches, GTx-sensitive current was the largest component of outward current with biophysical properties well-suited for regulating bursting. GTx drove ~40% of Thy1 PNs stimulated with noisy somatic current steps to repetitive burst firing and shifted the maximal frequency-dependent gain. A network model showed that reduction of Kv2-like conductance in a small subset of neurons resulted in repetitive bursting and entrainment of the circuit to seizure-like rhythmic activity. Kv2 channels play a dominant role in regulating onset bursts and preventing repetitive bursting in Thy1 PNs.
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Affiliation(s)
- Greg S Newkirk
- Department of Physiology and Biophysics, University of Washington, Seattle, WA 98195, USA
| | - Dongxu Guan
- Department of Anatomy and Neurobiology, Neuroscience Institute, University of Tennessee Health Science Center, Memphis, TN 38163, USA
| | - Nikolai Dembrow
- Department of Physiology and Biophysics, University of Washington, Seattle, WA 98195, USA.,Epilepsy Center of Excellence, Veterans Affairs Puget Sound Health Care System, Seattle, WA 98108, USA
| | - William E Armstrong
- Department of Anatomy and Neurobiology, Neuroscience Institute, University of Tennessee Health Science Center, Memphis, TN 38163, USA
| | - Robert C Foehring
- Department of Anatomy and Neurobiology, Neuroscience Institute, University of Tennessee Health Science Center, Memphis, TN 38163, USA
| | - William J Spain
- Department of Physiology and Biophysics, University of Washington, Seattle, WA 98195, USA.,Epilepsy Center of Excellence, Veterans Affairs Puget Sound Health Care System, Seattle, WA 98108, USA
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21
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Abstract
The presence of unprovoked, recurrent seizures, particularly when drug resistant and associated with cognitive and behavioral deficits, warrants investigation for an underlying genetic cause. This article provides an overview of the major classes of genes associated with epilepsy phenotypes divided into functional categories along with the recommended work-up and therapeutic considerations. Gene discovery in epilepsy supports counseling and anticipatory guidance but also opens the door for precision medicine guiding therapy with a focus on those with disease-modifying effects.
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Affiliation(s)
- Luis A Martinez
- Department of Pediatrics, Section of Pediatric Neurology and Developmental Neuroscience, Baylor College of Medicine, Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, 1250 Moursund Drive, Houston, TX 77030, USA
| | - Yi-Chen Lai
- Department of Pediatrics, Section of Pediatric Critical Care Medicine, Baylor College of Medicine, Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, 1250 Moursund Drive, Houston, TX 77030, USA
| | - J Lloyd Holder
- Department of Pediatrics, Section of Pediatric Neurology and Developmental Neuroscience, Baylor College of Medicine, Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, 1250 Moursund Drive, Houston, TX 77030, USA
| | - Anne E Anderson
- Department of Pediatrics, Section of Pediatric Neurology and Developmental Neuroscience, Baylor College of Medicine, Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, 1250 Moursund Drive, Houston, TX 77030, USA.
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22
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Spagnoli C, Fusco C, Pisani F. Rett Syndrome Spectrum in Monogenic Developmental-Epileptic Encephalopathies and Epilepsies: A Review. Genes (Basel) 2021; 12:genes12081157. [PMID: 34440332 PMCID: PMC8394997 DOI: 10.3390/genes12081157] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Revised: 07/21/2021] [Accepted: 07/23/2021] [Indexed: 01/22/2023] Open
Abstract
INTRODUCTION Progress in the clinical application of next-generation-sequencing-based techniques has resulted in a dramatic increase in the recognized genetic heterogeneity of the Rett syndrome spectrum (RSS). Our awareness of the considerable overlap with pediatric-onset epilepsies and epileptic/developmental encephalopathies (EE/DE) genes is also growing, and the presence of variable clinical features inside a general frame of commonalities has drawn renewed attention into deep phenotyping. METHODS We decided to review the medical literature on atypical Rett syndrome and "Rett-like" phenotypes, with special emphasis on described cases with pediatric-onset epilepsies and/or EE-DE, evaluating Neul's criteria for Rett syndrome and associated movement disorders and notable stereotypies. RESULTS "Rett-like" features were described in syndromic and non-syndromic monogenic epilepsy- and DE/EE-related genes, in "intellectual disability plus epilepsy"-related genes and in neurodegenerative disorders. Additionally, prominent stereotypies can be observed in monogenic complex neurodevelopmental disorders featuring epilepsy with or without autistic features outside of the RSS. CONCLUSIONS Patients share a complex neurodevelopmental and neurological phenotype (developmental delay, movement disorder) with impaired gait, abnormal tone and hand stereotypies. However, the presence and characteristics of regression and loss of language and functional hand use can differ. Finally, the frequency of additional supportive criteria and their distribution also vary widely.
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Affiliation(s)
- Carlotta Spagnoli
- Child Neurology Unit, AUSL-IRCCS di Reggio Emilia, 42123 Reggio Emilia, Italy;
- Correspondence:
| | - Carlo Fusco
- Child Neurology Unit, AUSL-IRCCS di Reggio Emilia, 42123 Reggio Emilia, Italy;
| | - Francesco Pisani
- Child Neuropsychiatry Unit, University-Hospital of Parma, 43123 Parma, Italy;
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23
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Mayo S, Gómez-Manjón I, Fernández-Martínez FJ, Camacho A, Martínez F, Benito-León J. Candidate Genes for Eyelid Myoclonia with Absences, Review of the Literature. Int J Mol Sci 2021; 22:ijms22115609. [PMID: 34070602 PMCID: PMC8199219 DOI: 10.3390/ijms22115609] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Revised: 05/19/2021] [Accepted: 05/21/2021] [Indexed: 01/11/2023] Open
Abstract
Eyelid myoclonia with absences (EMA), also known as Jeavons syndrome (JS) is a childhood onset epileptic syndrome with manifestations involving a clinical triad of absence seizures with eyelid myoclonia (EM), photosensitivity (PS), and seizures or electroencephalogram (EEG) paroxysms induced by eye closure. Although a genetic contribution to this syndrome is likely and some genetic alterations have been defined in several cases, the genes responsible for have not been identified. In this review, patients diagnosed with EMA (or EMA-like phenotype) with a genetic diagnosis are summarized. Based on this, four genes could be associated to this syndrome (SYNGAP1, KIA02022/NEXMIF, RORB, and CHD2). Moreover, although there is not enough evidence yet to consider them as candidate for EMA, three more genes present also different alterations in some patients with clinical diagnosis of the disease (SLC2A1, NAA10, and KCNB1). Therefore, a possible relationship of these genes with the disease is discussed in this review.
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Affiliation(s)
- Sonia Mayo
- Genetics and Inheritance Research Group, Instituto de Investigación Sanitaria Hospital 12 de Octubre (imas12), 28041 Madrid, Spain; (I.G.-M.); (F.J.F.-M.)
- Correspondence: ; Tel.: +34-91-779-2603
| | - Irene Gómez-Manjón
- Genetics and Inheritance Research Group, Instituto de Investigación Sanitaria Hospital 12 de Octubre (imas12), 28041 Madrid, Spain; (I.G.-M.); (F.J.F.-M.)
- Department of Genetics, Hospital Universitario 12 de Octubre, 28041 Madrid, Spain
| | - Fco. Javier Fernández-Martínez
- Genetics and Inheritance Research Group, Instituto de Investigación Sanitaria Hospital 12 de Octubre (imas12), 28041 Madrid, Spain; (I.G.-M.); (F.J.F.-M.)
- Department of Genetics, Hospital Universitario 12 de Octubre, 28041 Madrid, Spain
| | - Ana Camacho
- Department of Neurology, Division of Pediatric Neurology, Hospital Universitario 12 de Octubre, Universidad Complutense de Madrid, 28041 Madrid, Spain;
| | - Francisco Martínez
- Traslational Research in Genetics, Instituto de Investigación Sanitaria La Fe (IIS La Fe), 46026 Valencia, Spain;
- Genetics Unit, Hospital Universitario y Politecnico La Fe, 46026 Valencia, Spain
| | - Julián Benito-León
- Department of Neurology, Hospital Universitario 12 de Octubre, 28041 Madrid, Spain;
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), 28031 Madrid, Spain
- Department of Medicine, Universidad Complutense de Madrid, 28040 Madrid, Spain
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24
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Lee MC, Nahorski MS, Hockley JRF, Lu VB, Ison G, Pattison LA, Callejo G, Stouffer K, Fletcher E, Brown C, Drissi I, Wheeler D, Ernfors P, Menon D, Reimann F, Smith ESJ, Woods CG. Human Labor Pain Is Influenced by the Voltage-Gated Potassium Channel K V6.4 Subunit. Cell Rep 2021; 32:107941. [PMID: 32697988 PMCID: PMC7383234 DOI: 10.1016/j.celrep.2020.107941] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 03/19/2020] [Accepted: 06/30/2020] [Indexed: 12/22/2022] Open
Abstract
By studying healthy women who do not request analgesia during their first delivery, we investigate genetic effects on labor pain. Such women have normal sensory and psychometric test results, except for significantly higher cuff pressure pain. We find an excess of heterozygotes carrying the rare allele of SNP rs140124801 in KCNG4. The rare variant KV6.4-Met419 has a dominant-negative effect and cannot modulate the voltage dependence of KV2.1 inactivation because it fails to traffic to the plasma membrane. In vivo, Kcng4 (KV6.4) expression occurs in 40% of retrograde-labeled mouse uterine sensory neurons, all of which express KV2.1, and over 90% express the nociceptor genes Trpv1 and Scn10a. In neurons overexpressing KV6.4-Met419, the voltage dependence of inactivation for KV2.1 is more depolarized compared with neurons overexpressing KV6.4. Finally, KV6.4-Met419-overexpressing neurons have a higher action potential threshold. We conclude that KV6.4 can influence human labor pain by modulating the excitability of uterine nociceptors. KCNG4 variant highly prevalent in women requiring no analgesia in childbirth KCNG4 variant encodes KV6.4Met-419; KV6.4 is a silent subunit modifying KV activity KV6.4Met-419 is retained in the cytoplasm and acts in a dominant-negative manner KV6.4Met-419 overexpression results in hypoexcitable sensory neurons
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Affiliation(s)
- Michael C Lee
- University Division of Anaesthesia, University of Cambridge, Addenbrooke's Hospital, Hills Road, Cambridge CB2 0QQ, UK.
| | - Michael S Nahorski
- Cambridge Institute for Medical Research, Wellcome Trust MRC Building, Addenbrooke's Hospital, Hills Road, Cambridge CB2 0QQ, UK
| | - James R F Hockley
- Department of Pharmacology, Tennis Court Road, Cambridge CB2 1PD, UK
| | - Van B Lu
- Wellcome Trust-MRC Institute of Metabolic Science, Addenbrooke's Hospital, Hills Road, Cambridge CB2 0QQ, UK
| | - Gillian Ison
- University Division of Anaesthesia, University of Cambridge, Addenbrooke's Hospital, Hills Road, Cambridge CB2 0QQ, UK
| | - Luke A Pattison
- Department of Pharmacology, Tennis Court Road, Cambridge CB2 1PD, UK
| | - Gerard Callejo
- Department of Pharmacology, Tennis Court Road, Cambridge CB2 1PD, UK
| | - Kaitlin Stouffer
- Cambridge Institute for Medical Research, Wellcome Trust MRC Building, Addenbrooke's Hospital, Hills Road, Cambridge CB2 0QQ, UK
| | - Emily Fletcher
- Cambridge Institute for Medical Research, Wellcome Trust MRC Building, Addenbrooke's Hospital, Hills Road, Cambridge CB2 0QQ, UK
| | - Christopher Brown
- Department of Psychological Sciences, Institute of Psychology, Health and Society, University of Liverpool, Liverpool L69 7ZA, UK
| | - Ichrak Drissi
- University Division of Anaesthesia, University of Cambridge, Addenbrooke's Hospital, Hills Road, Cambridge CB2 0QQ, UK
| | - Daniel Wheeler
- University Division of Anaesthesia, University of Cambridge, Addenbrooke's Hospital, Hills Road, Cambridge CB2 0QQ, UK
| | - Patrik Ernfors
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, 171 77 Stockholm, Sweden
| | - David Menon
- University Division of Anaesthesia, University of Cambridge, Addenbrooke's Hospital, Hills Road, Cambridge CB2 0QQ, UK
| | - Frank Reimann
- Wellcome Trust-MRC Institute of Metabolic Science, Addenbrooke's Hospital, Hills Road, Cambridge CB2 0QQ, UK.
| | | | - C Geoffrey Woods
- Cambridge Institute for Medical Research, Wellcome Trust MRC Building, Addenbrooke's Hospital, Hills Road, Cambridge CB2 0QQ, UK.
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25
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Nikitin ES, Vinogradova LV. Potassium channels as prominent targets and tools for the treatment of epilepsy. Expert Opin Ther Targets 2021; 25:223-235. [PMID: 33754930 DOI: 10.1080/14728222.2021.1908263] [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] [Indexed: 10/21/2022]
Abstract
INTRODUCTION K+ channels are of great interest to epilepsy research as mutations in their genes are found in humans with inherited epilepsy. At the level of cellular physiology, K+ channels control neuronal intrinsic excitability and are the main contributors to membrane repolarization of active neurons. Recently, a genetically modified voltage-dependent K+ channel has been patented as a remedy for epileptic seizures. AREAS COVERED We review the role of potassium channels in excitability, clinical and experimental evidence for the association of potassium channelopathies with epilepsy, the targeting of K+ channels by drugs, and perspectives of gene therapy in epilepsy with the expression of extra K+ channels in the brain. EXPERT OPINION Control over K+ conductance is of great potential benefit for the treatment of epilepsy. Nowadays, gene therapy affecting K+ channels is one of the most promising approaches to treat pharmacoresistant focal epilepsy.
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Affiliation(s)
- E S Nikitin
- Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences, Moscow, Russia
| | - L V Vinogradova
- Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences, Moscow, Russia
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26
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Deardorff AS, Romer SH, Fyffe RE. Location, location, location: the organization and roles of potassium channels in mammalian motoneurons. J Physiol 2021; 599:1391-1420. [DOI: 10.1113/jp278675] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2020] [Accepted: 01/08/2021] [Indexed: 11/08/2022] Open
Affiliation(s)
- Adam S. Deardorff
- Department of Neuroscience, Cell Biology and Physiology, Wright State University Boonshoft School of Medicine Dayton OH 45435 USA
- Department of Neurology and Internal Medicine, Wright State University Boonshoft School of Medicine Dayton OH 45435 USA
| | - Shannon H. Romer
- Odyssey Systems Environmental Health Effects Laboratory, Navy Medical Research Unit‐Dayton Wright‐Patterson Air Force Base OH 45433 USA
| | - Robert E.W. Fyffe
- Department of Neuroscience, Cell Biology and Physiology, Wright State University Boonshoft School of Medicine Dayton OH 45435 USA
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27
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Hawkins NA, Misra SN, Jurado M, Kang SK, Vierra NC, Nguyen K, Wren L, George AL, Trimmer JS, Kearney JA. Epilepsy and neurobehavioral abnormalities in mice with a dominant-negative KCNB1 pathogenic variant. Neurobiol Dis 2020; 147:105141. [PMID: 33132203 PMCID: PMC7725922 DOI: 10.1016/j.nbd.2020.105141] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2020] [Revised: 10/04/2020] [Accepted: 10/12/2020] [Indexed: 11/23/2022] Open
Abstract
Developmental and epileptic encephalopathies (DEE) are a group of severe epilepsies that usually present with intractable seizures, developmental delay, and often have elevated risk for premature mortality. Numerous genes have been identified as a monogenic cause of DEE, including KCNB1. The voltage-gated potassium channel Kv2.1, encoded by KCNB1, is primarily responsible for delayed rectifier potassium currents that are important regulators of excitability in electrically excitable cells, including neurons. In addition to its canonical role as a voltage-gated potassium conductance, Kv2.1 also serves a highly conserved structural function organizing endoplasmic reticulum-plasma membrane junctions clustered in the soma and proximal dendrites of neurons. The de novo pathogenic variant KCNB1-p.G379R was identified in an infant with epileptic spasms, and atonic, focal and tonic-clonic seizures that were refractory to treatment with standard antiepileptic drugs. Previous work demonstrated deficits in potassium conductance, but did not assess non-conducting functions. To determine if the G379R variant affected Kv2.1 clustering at endoplasmic reticulum-plasma membrane junctions, Kv2.1-G379R was expressed in HEK293T cells. Kv2.1-G379R expression did not induce formation of endoplasmic reticulum-plasma membrane junctions, and co-expression of Kv2.1-G379R with Kv2.1-wild-type lowered induction of these structures relative to Kv2.1-WT alone, consistent with a dominant negative effect. To model this variant in vivo, we introduced Kcnb1G379R into mice using CRISPR/Cas9 genome editing. We characterized neuronal expression, neurological and neurobehavioral phenotypes of Kcnb1G379R/+ (Kcnb1R/+) and Kcnb1G379R/G379R (Kcnb1R/R) mice. Immunohistochemistry studies on brains from Kcnb1+/+, Kcnb1R/+ and Kcnb1R/R mice revealed genotype-dependent differences in the expression levels of Kv2.1 protein, as well as associated Kv2.2 and AMIGO-1 proteins. Kcnb1R/+ and Kcnb1R/R mice displayed profound hyperactivity, repetitive behaviors, impulsivity and reduced anxiety. Spontaneous seizures were observed in Kcnb1R/R mice, as well as seizures induced by exposure to novel environments and/ or handling. Both Kcnb1R/+ and Kcnb1R/R mutants were more susceptible to proconvulsant-induced seizures. In addition, both Kcnb1R/+ and Kcnb1R/R mice exhibited abnormal interictal EEG activity, including isolated spike and slow waves. Overall, the Kcnb1G379R mice recapitulate many features observed in individuals with DEE due to pathogenic variants in KCNB1. This new mouse model of KCNB1-associated DEE will be valuable for improving the understanding of the underlying pathophysiology and will provide a valuable tool for the development of therapies to treat this pharmacoresistant DEE.
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Affiliation(s)
- Nicole A Hawkins
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, United States of America
| | - Sunita N Misra
- Department of Pediatrics, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, United States of America; Ann & Robert H. Lurie Children's Hospital of Chicago Chicago, IL 60611, United States of America
| | - Manuel Jurado
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, United States of America
| | - Seok Kyu Kang
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, United States of America
| | - Nicholas C Vierra
- Department of Neurobiology, Physiology and Behavior, University of California, Davis, CA 95616, United States of America; Department of preceding Physiology and Membrane Biology, University of California, Davis, CA 95616, United States of America
| | - Kimberly Nguyen
- Department of Neurobiology, Physiology and Behavior, University of California, Davis, CA 95616, United States of America
| | - Lisa Wren
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, United States of America
| | - Alfred L George
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, United States of America
| | - James S Trimmer
- Department of Neurobiology, Physiology and Behavior, University of California, Davis, CA 95616, United States of America; Department of preceding Physiology and Membrane Biology, University of California, Davis, CA 95616, United States of America
| | - Jennifer A Kearney
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, United States of America.
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28
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Bar C, Kuchenbuch M, Barcia G, Schneider A, Jennesson M, Le Guyader G, Lesca G, Mignot C, Montomoli M, Parrini E, Isnard H, Rolland A, Keren B, Afenjar A, Dorison N, Sadleir LG, Breuillard D, Levy R, Rio M, Dupont S, Negrin S, Danieli A, Scalais E, De Saint Martin A, El Chehadeh S, Chelly J, Poisson A, Lebre A, Nica A, Odent S, Sekhara T, Brankovic V, Goldenberg A, Vrielynck P, Lederer D, Maurey H, Terrone G, Besmond C, Hubert L, Berquin P, Billette de Villemeur T, Isidor B, Freeman JL, Mefford HC, Myers CT, Howell KB, Rodríguez‐Sacristán Cascajo A, Meyer P, Genevieve D, Guët A, Doummar D, Durigneux J, van Dooren MF, de Wit MCY, Gerard M, Marey I, Munnich A, Guerrini R, Scheffer IE, Kabashi E, Nabbout R. Developmental and epilepsy spectrum of
KCNB1
encephalopathy with long‐term outcome. Epilepsia 2020; 61:2461-2473. [DOI: 10.1111/epi.16679] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Revised: 08/11/2020] [Accepted: 08/11/2020] [Indexed: 12/11/2022]
Affiliation(s)
- Claire Bar
- Department of Pediatric Neurology Reference Center for Rare Epilepsies Assistance Publique‐Hôpitaux de Paris (AP‐HP), Necker‐Enfants Malades Hospital Paris France
- Imagine Institute, Mixed Unit of Research 1163 University of ParisSorbonne University Paris France
| | - Mathieu Kuchenbuch
- Department of Pediatric Neurology Reference Center for Rare Epilepsies Assistance Publique‐Hôpitaux de Paris (AP‐HP), Necker‐Enfants Malades Hospital Paris France
- Imagine Institute, Mixed Unit of Research 1163 University of ParisSorbonne University Paris France
| | - Giulia Barcia
- Imagine Institute, Mixed Unit of Research 1163 University of ParisSorbonne University Paris France
- Department of Clinical Genetics AP‐HP, Necker‐Enfants Malades Hospital Paris France
| | - Amy Schneider
- Department of Medicine Epilepsy Research Centre Austin Health University of Melbourne Heidelberg Victoria Australia
| | | | - Gwenaël Le Guyader
- Department of Genetics Poitiers University Hospital CenterPoitiers Cedex France
- EA3808–NEUVACOD Neurovascular and Cognitive Disorders Unit University of Poitiers Poitiers France
| | - Gaetan Lesca
- Department of Genetics Lyon Civil Hospices Lyon France
- NeuroMyoGène Institute National Center for Scientific Research Mixed Unit of Research 5310, National Institute of Health and Medical Research U1217University of LyonClaude Bernard Lyon 1 University Villeurbanne France
| | - Cyril Mignot
- National Institute of Health and Medical Research, U1127 National Center for Scientific Research Mixed Unit of Research 7225 Pierre and Marie Curie University Paris 6 Mixed Unit of Research S1127 Brain and Spine Institute Sorbonne University Paris France
- Department of Genetics Rare Causes of Intellectual Disability Reference Center AP‐HP, Pitié‐Salpêtrière HospitalSorbonne University Paris France
| | - Martino Montomoli
- Pediatric Neurology, Neurogenetics, and Neurobiology Unit and Laboratories Neuroscience Department A. Meyer Children's HospitalUniversity of Florence Florence Italy
| | - Elena Parrini
- Pediatric Neurology, Neurogenetics, and Neurobiology Unit and Laboratories Neuroscience Department A. Meyer Children's HospitalUniversity of Florence Florence Italy
| | - Hervé Isnard
- Pediatric Neurologist Medical Office Lyon France
| | - Anne Rolland
- Department of Pediatrics Nantes University Hospital Center Nantes France
| | - Boris Keren
- Department of Genetics Rare Causes of Intellectual Disability Reference Center AP‐HP, Pitié‐Salpêtrière HospitalSorbonne University Paris France
| | - Alexandra Afenjar
- Department of Genetics and Medical Embryology Reference Center for Malformations and Congenital Diseases of the Cerebellum and Rare Causes of Intellectual Disabilities Sorbonne UniversityAP‐HP, Trousseau Hospital Paris France
| | - Nathalie Dorison
- Pediatric Neurosurgery Department Rothschild Foundation Hospital Paris France
- Department of Pediatric Neurology AP‐HP, Armand Trousseau HospitalSorbonne University Paris France
| | - Lynette G. Sadleir
- Department of Pediatrics and Child Health University of Otago Wellington New Zealand
| | - Delphine Breuillard
- Department of Pediatric Neurology Reference Center for Rare Epilepsies Assistance Publique‐Hôpitaux de Paris (AP‐HP), Necker‐Enfants Malades Hospital Paris France
- Imagine Institute, Mixed Unit of Research 1163 University of ParisSorbonne University Paris France
| | - Raphael Levy
- Department of Pediatric Radiology Necker‐Enfants Malades Hospital Paris France
| | - Marlène Rio
- Department of Clinical Genetics AP‐HP, Necker‐Enfants Malades Hospital Paris France
- Laboratory of Developmental Brain Disorders National Institute of Health and Medical Research Mixed Unit of Research 1163 Imagine InstituteSorbonne University Paris France
| | - Sophie Dupont
- National Institute of Health and Medical Research, U1127 National Center for Scientific Research Mixed Unit of Research 7225 Pierre and Marie Curie University Paris 6 Mixed Unit of Research S1127 Brain and Spine Institute Sorbonne University Paris France
- Epileptology Unit and Rehabilitation Unit AP‐HP, Pitie‐Salpêtrière‐Charles Foix Hospital Paris France
| | - Susanna Negrin
- Epilepsy and Clinical Neurophysiology Unit Scientific InstituteIRCCS E. Medea Treviso Italy
| | - Alberto Danieli
- Epilepsy and Clinical Neurophysiology Unit Scientific InstituteIRCCS E. Medea Treviso Italy
| | - Emmanuel Scalais
- Pediatric Neurology Unit Luxembourg Hospital Center Luxembourg City Luxembourg
| | - Anne De Saint Martin
- Department of Pediatric Neurology Strasbourg University HospitalHautepierre Hospital Strasbourg France
| | - Salima El Chehadeh
- Department of Medical Genetics Strasbourg University HospitalsHautepierre Hospital Strasbourg France
| | - Jamel Chelly
- Department of Medical Genetics Strasbourg University HospitalsHautepierre Hospital Strasbourg France
| | - Alice Poisson
- GénoPsy Reference Center for Diagnosis and Management of Genetic Psychiatric Disorders le Vinatier Hospital Center and EDR‐Psy Team (National Center for Scientific Research and Lyon 1 Claude Bernard University) Villeurbanne France
| | - Anne‐Sophie Lebre
- Reims University Hospital CenterMaison Blanche HospitalBiology Department Reims France
| | - Anca Nica
- Neurology Department Center for Clinical Research (CIC 1414) Rennes University Hospital Rennes France
- Laboratory of Signal ProcessingNational Institute of Health and Medical Research Mixed Unit of Research 1099 Rennes France
| | - Sylvie Odent
- Reference Center for Rare Developmental Abnormalities CLAD‐Ouest Rennes University Hospital Center Rennes France
- National Center for Scientific Research Mixed Unit of Research 6290, Institute of Genetics and Development of Rennes (IGDR)University of Rennes Rennes France
| | - Tayeb Sekhara
- Department of Pediatric Neurology C.H.I.R.E.C Brussels Belgium
| | | | - Alice Goldenberg
- Reference Center for Developmental Anomalies and Malformation Syndromes Rouen University Hospital Center Rouen France
| | - Pascal Vrielynck
- Reference Center for Refractory Epilepsy, Catholic University of Louvain William Lennox Neurological Hospital Ottignies Belgium
| | | | - Hélène Maurey
- Department of Pediatric Neurology AP‐HP, Bicêtre University Hospital Kremlin Bicêtre France
| | - Gaetano Terrone
- Department of Translational Medical Sciences Section of Pediatrics, Child Neurology Unit Federico II University Naples Italy
| | - Claude Besmond
- Translational Genetics National Institute of Health and Medical Research Mixed Unit of Research 1163Imagine InstituteUniversity of Paris Paris France
| | - Laurence Hubert
- Translational Genetics National Institute of Health and Medical Research Mixed Unit of Research 1163Imagine InstituteUniversity of Paris Paris France
| | - Patrick Berquin
- Department of Pediatric Neurology Amiens‐Picardie University Hospital CenterUniversity of Picardy Jules Verne Amiens France
| | | | - Bertrand Isidor
- Department of Clinical Genetics Nantes University Hospital Center Nantes France
| | - Jeremy L. Freeman
- Departments of Neurology and Paediatrics Royal Children's Hospital University of Melbourne Melbourne Victoria Australia
- Murdoch Children’s Research Institute Melbourne Victoria Australia
| | - Heather C. Mefford
- Department of Pediatrics Division of Genetic Medicine University of Washington Seattle Washington United States
| | - Candace T. Myers
- Department of Pediatrics Division of Genetic Medicine University of Washington Seattle Washington United States
| | - Katherine B. Howell
- Departments of Neurology and Paediatrics Royal Children's Hospital University of Melbourne Melbourne Victoria Australia
- Murdoch Children’s Research Institute Melbourne Victoria Australia
| | - Andrés Rodríguez‐Sacristán Cascajo
- Pediatric Neurology Unit Department of Pediatric Virgen Macarena Hospital Seville Spain
- Department of Pediatrics School of Medicine University of Seville Seville Spain
| | - Pierre Meyer
- Department of Pediatric Neurology Montpellier University Hospital Center Montpellier France
- PhyMedExp National Institute of Health and Medical Research, U1046National Center for Scientific Research Mixed Unit of Research 9214University of Montpellier Montpellier France
| | - David Genevieve
- Department of Medical Genetics, Rare Disease, and Personalized Medicine IRMBUniversity of MontpellierNational Institute of Health and Medical ResearchMontpellier University Hospital Center Montpellier France
| | - Agnès Guët
- Department of Pediatrics Louis‐Mourier Hospital Colombes France
| | - Diane Doummar
- Department of Pediatric Neurology AP‐HP, Armand Trousseau HospitalSorbonne University Paris France
| | - Julien Durigneux
- Departments of Neurology and Paediatrics Royal Children's Hospital University of Melbourne Melbourne Victoria Australia
| | - Marieke F. van Dooren
- Department of Clinical Genetics Erasmus University Medical Center Rotterdam the Netherlands
| | - Marie Claire Y. de Wit
- Department of Pediatric Neurology and ENCORE Expertise Center Erasmus University Medical Center Sophia Children’s Hospital Rotterdam the Netherlands
| | - Marion Gerard
- Clinical Genetics Côte de Nacre University Hospital Center Caen France
| | - Isabelle Marey
- Department of Genetics Rare Causes of Intellectual Disability Reference Center AP‐HP, Pitié‐Salpêtrière HospitalSorbonne University Paris France
| | - Arnold Munnich
- Imagine Institute, Mixed Unit of Research 1163 University of ParisSorbonne University Paris France
- Department of Clinical Genetics AP‐HP, Necker‐Enfants Malades Hospital Paris France
| | - Renzo Guerrini
- Pediatric Neurology, Neurogenetics, and Neurobiology Unit and Laboratories Neuroscience Department A. Meyer Children's HospitalUniversity of Florence Florence Italy
| | - Ingrid E. Scheffer
- Department of Medicine Epilepsy Research Centre Austin Health University of Melbourne Heidelberg Victoria Australia
- Departments of Neurology and Paediatrics Royal Children's Hospital University of Melbourne Melbourne Victoria Australia
- Murdoch Children’s Research Institute Melbourne Victoria Australia
- Florey Institute of Neurosciences and Mental Health Heidelberg Victoria Australia
| | - Edor Kabashi
- Imagine Institute, Mixed Unit of Research 1163 University of ParisSorbonne University Paris France
| | - Rima Nabbout
- Department of Pediatric Neurology Reference Center for Rare Epilepsies Assistance Publique‐Hôpitaux de Paris (AP‐HP), Necker‐Enfants Malades Hospital Paris France
- Imagine Institute, Mixed Unit of Research 1163 University of ParisSorbonne University Paris France
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Akita T, Fukuda A. Intracellular Cl - dysregulation causing and caused by pathogenic neuronal activity. Pflugers Arch 2020; 472:977-987. [PMID: 32300887 DOI: 10.1007/s00424-020-02375-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Revised: 03/23/2020] [Accepted: 03/27/2020] [Indexed: 02/06/2023]
Abstract
The intracellular Cl- concentration ([Cl-]i) is tightly regulated in brain neurons for stabilizing brain performance. The [Cl-]i in mature neurons is determined by the balance between the rate of Cl- extrusion mainly mediated by the neuron-specific type 2 K+-Cl- cotransporter (KCC2) and the rate of Cl- entry through various Cl- channels including GABAA receptors during neuronal activity. Disturbance of the balance causes instability of brain circuit performance and may lead to epileptic seizures. In the first part of this review, we discuss how genetic alterations in KCC2 in humans cause infantile migrating focal seizures, based on our previous report and others. Depolarization of the membrane potential increases the driving force for Cl- entry into neurons. Thus, the duration of action potential spike generation and the frequency of excitatory synaptic inputs are the crucial factors for determining the total amount of Cl- entry and the equilibrium [Cl-]i in neurons. Moreover, there is also a significant interdependence between the neuronal activity and the KCC2 expression. In the second part, we discuss plausible mechanisms by which excessive neuronal activity due to excitotoxic brain insults or other epilepsy-associated gene mutations may cause the Cl- imbalance in neurons and lead to epileptic discharges over the brain, using the schematic "unifying foci" model based on literature.
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Affiliation(s)
- Tenpei Akita
- Department of Neurophysiology, Hamamatsu University School of Medicine, Hamamatsu, 431-3192, Japan.
| | - Atsuo Fukuda
- Department of Neurophysiology, Hamamatsu University School of Medicine, Hamamatsu, 431-3192, Japan
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30
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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: 29] [Impact Index Per Article: 7.3] [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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31
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Chow CY, Absalom N, Biggs K, King GF, Ma L. Venom-derived modulators of epilepsy-related ion channels. Biochem Pharmacol 2020; 181:114043. [PMID: 32445870 DOI: 10.1016/j.bcp.2020.114043] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Accepted: 05/18/2020] [Indexed: 12/18/2022]
Abstract
Epilepsy is characterised by spontaneous recurrent seizures that are caused by an imbalance between neuronal excitability and inhibition. Since ion channels play fundamental roles in the generation and propagation of action potentials as well as neurotransmitter release at a subset of excitatory and inhibitory synapses, their dysfunction has been linked to a wide variety of epilepsies. Indeed, these unique proteins are the major biological targets for antiepileptic drugs. Selective targeting of a specific ion channel subtype remains challenging for small molecules, due to the high level of homology among members of the same channel family. As a consequence, there is a growing trend to target ion channels with biologics. Venoms are the best known natural source of ion channel modulators, and venom peptides are increasingly recognised as potential therapeutics due to their high selectivity and potency gained through millions of years of evolutionary selection pressure. Here we describe the major ion channel families involved in the pathogenesis of various types of epilepsy, including voltage-gated Na+, K+, Ca2+ channels, Cys-loop receptors, ionotropic glutamate receptors and P2X receptors, and currently available venom-derived peptides that target these channel proteins. Although only a small number of venom peptides have successfully progressed to the clinic, there is reason to be optimistic about their development as antiepileptic drugs, notwithstanding the challenges associated with development of any class of peptide drug.
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Affiliation(s)
- Chun Yuen Chow
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Nathan Absalom
- Brain and Mind Centre, School of Pharmacy, Faculty of Health and Medicine, The University of Sydney, Sydney, NSW 2050, Australia
| | - Kimberley Biggs
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Glenn F King
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia.
| | - Linlin Ma
- Griffith Institute for Drug Discovery, Griffith University, Nathan, QLD 4111, Australia.
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32
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Tang S, Addis L, Smith A, Topp SD, Pendziwiat M, Mei D, Parker A, Agrawal S, Hughes E, Lascelles K, Williams RE, Fallon P, Robinson R, Cross HJ, Hedderly T, Eltze C, Kerr T, Desurkar A, Hussain N, Kinali M, Bagnasco I, Vassallo G, Whitehouse W, Goyal S, Absoud M, Møller RS, Helbig I, Weber YG, Marini C, Guerrini R, Simpson MA, Pal DK. Phenotypic and genetic spectrum of epilepsy with myoclonic atonic seizures. Epilepsia 2020; 61:995-1007. [PMID: 32469098 DOI: 10.1111/epi.16508] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Revised: 02/24/2020] [Accepted: 03/27/2020] [Indexed: 12/30/2022]
Abstract
OBJECTIVE We aimed to describe the extent of neurodevelopmental impairments and identify the genetic etiologies in a large cohort of patients with epilepsy with myoclonic atonic seizures (MAE). METHODS We deeply phenotyped MAE patients for epilepsy features, intellectual disability, autism spectrum disorder, and attention-deficit/hyperactivity disorder using standardized neuropsychological instruments. We performed exome analysis (whole exome sequencing) filtered on epilepsy and neuropsychiatric gene sets to identify genetic etiologies. RESULTS We analyzed 101 patients with MAE (70% male). The median age of seizure onset was 34 months (range = 6-72 months). The main seizure types were myoclonic atonic or atonic in 100%, generalized tonic-clonic in 72%, myoclonic in 69%, absence in 60%, and tonic seizures in 19% of patients. We observed intellectual disability in 62% of patients, with extremely low adaptive behavioral scores in 69%. In addition, 24% exhibited symptoms of autism and 37% exhibited attention-deficit/hyperactivity symptoms. We discovered pathogenic variants in 12 (14%) of 85 patients, including five previously published patients. These were pathogenic genetic variants in SYNGAP1 (n = 3), KIAA2022 (n = 2), and SLC6A1 (n = 2), as well as KCNA2, SCN2A, STX1B, KCNB1, and MECP2 (n = 1 each). We also identified three new candidate genes, ASH1L, CHD4, and SMARCA2 in one patient each. SIGNIFICANCE MAE is associated with significant neurodevelopmental impairment. MAE is genetically heterogeneous, and we identified a pathogenic genetic etiology in 14% of this cohort by exome analysis. These findings suggest that MAE is a manifestation of several etiologies rather than a discrete syndromic entity.
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Affiliation(s)
- Shan Tang
- Evelina London Children's Hospital, London, UK
- Institute of Psychiatry, Psychology, and Neuroscience, King's College London, London, UK
| | - Laura Addis
- Institute of Psychiatry, Psychology, and Neuroscience, King's College London, London, UK
- Eli Lilly and Company, Erl Wood, Surrey, UK
| | - Anna Smith
- Institute of Psychiatry, Psychology, and Neuroscience, King's College London, London, UK
| | - Simon D Topp
- Institute of Psychiatry, Psychology, and Neuroscience, King's College London, London, UK
| | - Manuela Pendziwiat
- Clinic for Neuropediatrics, Schleswig-Holstein University Clinics, Kiel, Germany
| | - Davide Mei
- Meyer Children's Hospital, University of Florence, Florence, Italy
| | | | - Shakti Agrawal
- Birmingham Children's Hospital National Health Service Foundation Trust, Birmingham, UK
| | - Elaine Hughes
- Evelina London Children's Hospital, London, UK
- King's College Hospital, London, UK
| | | | | | - Penny Fallon
- St George's National Health Service Health Care Trust, London, UK
| | - Robert Robinson
- Great Ormond Street Hospital for Children National Health Service Trust, London, UK
| | - Helen J Cross
- Great Ormond Street Hospital for Children National Health Service Trust, London, UK
- Clinical Neurosciences, UCL - Institute of Child Health, London, UK
| | | | - Christin Eltze
- Great Ormond Street Hospital for Children National Health Service Trust, London, UK
| | - Tim Kerr
- St George's National Health Service Health Care Trust, London, UK
| | - Archana Desurkar
- Sheffield Children's National Health Service Foundation Trust, Sheffield, UK
| | - Nahin Hussain
- University Hospital of Leicester National Health Service Trust, Leicester, UK
| | - Maria Kinali
- Chelsea and Westminster Hospital National Health Service Foundation Trust, London, UK
| | - Irene Bagnasco
- Child Neurology and Psychiatry Unit, Martini Hospital, Turin, Italy
| | | | | | - Sushma Goyal
- Evelina London Children's Hospital, London, UK
- King's College Hospital, London, UK
| | | | | | - Ingo Helbig
- Clinic for Neuropediatrics, Schleswig-Holstein University Clinics, Kiel, Germany
- Division of Neurology, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania
- Epilepsy NeuroGenetics Initiative, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania
- Department of Biomedical and Health Informatics, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania
- Department of Neurology, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Yvonne G Weber
- Department of Neurology and Epileptology, Hertie Institute for Clinical Brain Research, Tübingen, Germany
- Department of Neurosurgery, University of Tübingen, Tübingen, Germany
| | - Carla Marini
- Meyer Children's Hospital, University of Florence, Florence, Italy
| | - Renzo Guerrini
- Meyer Children's Hospital, University of Florence, Florence, Italy
| | - Michael A Simpson
- Division of Genetics and Molecular Medicine, King's College London, London, UK
| | - Deb K Pal
- Evelina London Children's Hospital, London, UK
- Institute of Psychiatry, Psychology, and Neuroscience, King's College London, London, UK
- King's College Hospital, London, UK
- Medical Research Council Centre for Neurodevelopmental Disorders, King's College London, London, UK
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33
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Samanta D. Epileptic spasm and de novo KCNB1 mutation: if it is not one potassium channel, it is another! Acta Neurol Belg 2020; 120:417-420. [PMID: 29808309 DOI: 10.1007/s13760-018-0950-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Accepted: 05/20/2018] [Indexed: 11/24/2022]
Affiliation(s)
- Debopam Samanta
- Child Neurology Division, Department of Pediatrics, University of Arkansas for Medical Sciences, 1 Children's Way, Little Rock, AR, 72202, USA.
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34
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Al Hajri Q, Dash S, Feng WC, Garner HR, Anandakrishnan R. Identifying multi-hit carcinogenic gene combinations: Scaling up a weighted set cover algorithm using compressed binary matrix representation on a GPU. Sci Rep 2020; 10:2022. [PMID: 32029803 PMCID: PMC7005272 DOI: 10.1038/s41598-020-58785-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Accepted: 01/20/2020] [Indexed: 01/16/2023] Open
Abstract
Despite decades of research, effective treatments for most cancers remain elusive. One reason is that different instances of cancer result from different combinations of multiple genetic mutations (hits). Therefore, treatments that may be effective in some cases are not effective in others. We previously developed an algorithm for identifying combinations of carcinogenic genes with mutations (multi-hit combinations), which could suggest a likely cause for individual instances of cancer. Most cancers are estimated to require three or more hits. However, the computational complexity of the algorithm scales exponentially with the number of hits, making it impractical for identifying combinations of more than two hits. To identify combinations of greater than two hits, we used a compressed binary matrix representation, and optimized the algorithm for parallel execution on an NVIDIA V100 graphics processing unit (GPU). With these enhancements, the optimized GPU implementation was on average an estimated 12,144 times faster than the original integer matrix based CPU implementation, for the 3-hit algorithm, allowing us to identify 3-hit combinations. The 3-hit combinations identified using a training set were able to differentiate between tumor and normal samples in a separate test set with 90% overall sensitivity and 93% overall specificity. We illustrate how the distribution of mutations in tumor and normal samples in the multi-hit gene combinations can suggest potential driver mutations for further investigation. With experimental validation, these combinations may provide insight into the etiology of cancer and a rational basis for targeted combination therapy.
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Affiliation(s)
- Qais Al Hajri
- Department of Electrical and Computer Engineering, Virginia Tech, Blacksburg, VA, 24060, USA
| | - Sajal Dash
- Department of Computer Science, Virginia Tech, Blacksburg, VA, 24060, USA
| | - Wu-Chun Feng
- Department of Electrical and Computer Engineering, Virginia Tech, Blacksburg, VA, 24060, USA
- Department of Computer Science, Virginia Tech, Blacksburg, VA, 24060, USA
| | - Harold R Garner
- Department of Biomedical Sciences, Edward Via College of Osteopathic Medicine, Blacksburg, VA, 24060, USA
- Gibbs Cancer Center and Research Institute, Spartanburg, SC, 29303, USA
| | - Ramu Anandakrishnan
- Department of Biomedical Sciences, Edward Via College of Osteopathic Medicine, Blacksburg, VA, 24060, USA.
- Gibbs Cancer Center and Research Institute, Spartanburg, SC, 29303, USA.
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35
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Papandreou A, Danti FR, Spaull R, Leuzzi V, Mctague A, Kurian MA. The expanding spectrum of movement disorders in genetic epilepsies. Dev Med Child Neurol 2020; 62:178-191. [PMID: 31784983 DOI: 10.1111/dmcn.14407] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 03/01/2019] [Indexed: 12/27/2022]
Abstract
An ever-increasing number of neurogenetic conditions presenting with both epilepsy and atypical movements are now recognized. These disorders within the 'genetic epilepsy-dyskinesia' spectrum are clinically and genetically heterogeneous. Increased clinical awareness is therefore necessary for a rational diagnostic approach. Furthermore, careful interpretation of genetic results is key to establishing the correct diagnosis and initiating disease-specific management strategies in a timely fashion. In this review we describe the spectrum of movement disorders associated with genetically determined epilepsies. We also propose diagnostic strategies and putative pathogenic mechanisms causing these complex syndromes associated with both seizures and atypical motor control. WHAT THIS PAPER ADDS: Implicated genes encode proteins with very diverse functions. Pathophysiological mechanisms by which epilepsy and movement disorder phenotypes manifest are often not clear. Early diagnosis of treatable disorders is essential and next generation sequencing may be required.
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Affiliation(s)
- Apostolos Papandreou
- Molecular Neurosciences, Developmental Neurosciences Programme, UCL Great Ormond Street Institute of Child Health, London, UK
- Department of Neurology, Great Ormond Street Hospital, London, UK
| | - Federica Rachele Danti
- Molecular Neurosciences, Developmental Neurosciences Programme, UCL Great Ormond Street Institute of Child Health, London, UK
- Department of Human Neuroscience, Unit of Child Neurology and Psychiatry, Sapienza University of Rome, Rome, Italy
| | - Robert Spaull
- Department of Paediatric Neurology, Bristol Royal Hospital for Children, Bristol, UK
- Bristol Medical School, University of Bristol, Bristol, UK
| | - Vincenzo Leuzzi
- Department of Human Neuroscience, Unit of Child Neurology and Psychiatry, Sapienza University of Rome, Rome, Italy
| | - Amy Mctague
- Molecular Neurosciences, Developmental Neurosciences Programme, UCL Great Ormond Street Institute of Child Health, London, UK
- Department of Neurology, Great Ormond Street Hospital, London, UK
| | - Manju A Kurian
- Molecular Neurosciences, Developmental Neurosciences Programme, UCL Great Ormond Street Institute of Child Health, London, UK
- Department of Neurology, Great Ormond Street Hospital, London, UK
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36
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Yu W, Shin MR, Sesti F. Complexes formed with integrin-α5 and KCNB1 potassium channel wild type or epilepsy-susceptibility variants modulate cellular plasticity via Ras and Akt signaling. FASEB J 2019; 33:14680-14689. [PMID: 31682765 DOI: 10.1096/fj.201901792r] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Voltage-gated potassium (K+) channel subfamily B member 1 (KCNB1, Kv2.1) and integrin-α5 form macromolecular complexes-named integrin-α5-KCNB1 complexes (IKCs)-in the human brain, but their function was poorly understood. Here we report that membrane depolarization triggered IKC intracellular signals mediated by small GTPases of the Ras subfamily and protein kinase B (Akt) to advance the development of filopodia and lamellipodia in Chinese hamster ovary cells, stimulate their motility, and enhance neurite outgrowth in mouse neuroblastoma Neuro2a cells. Five KCNB1 mutants (L211P, R312H G379R, G381R, and F416L) linked to severe infancy or early-onset epileptic encephalopathy exhibited markedly defective conduction. However, although L211P, G379R, and G381R normally engaged Ras/Akt and stimulated cell migration, R312H and F416L failed to activate Ras/Akt signaling and did not enhance cell migration. Taken together, these data suggest that IKCs modulate cellular plasticity via Ras and Akt signaling. As such, defective IKCs may cause epilepsy through mechanisms other than dysregulated excitability such as, for example, abnormal neuronal development and resulting synaptic connectivity.-Yu, W., Shin, M. R., Sesti, F. Complexes formed with integrin-α5 and KCNB1 potassium channel wild type or epilepsy-susceptibility variants modulate cellular plasticity via Ras and Akt signaling.
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Affiliation(s)
- Wei Yu
- Department of Neuroscience and Cell Biology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, New Jersey, USA
| | - Mi Ryung Shin
- Department of Neuroscience and Cell Biology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, New Jersey, USA
| | - Federico Sesti
- Department of Neuroscience and Cell Biology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, New Jersey, USA
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37
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Kang SK, Vanoye CG, Misra SN, Echevarria DM, Calhoun JD, O'Connor JB, Fabre KL, McKnight D, Demmer L, Goldenberg P, Grote LE, Thiffault I, Saunders C, Strauss KA, Torkamani A, van der Smagt J, van Gassen K, Carson RP, Diaz J, Leon E, Jacher JE, Hannibal MC, Litwin J, Friedman NR, Schreiber A, Lynch B, Poduri A, Marsh ED, Goldberg EM, Millichap JJ, George AL, Kearney JA. Spectrum of K V 2.1 Dysfunction in KCNB1-Associated Neurodevelopmental Disorders. Ann Neurol 2019; 86:899-912. [PMID: 31600826 DOI: 10.1002/ana.25607] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Revised: 09/16/2019] [Accepted: 09/16/2019] [Indexed: 12/13/2022]
Abstract
OBJECTIVE Pathogenic variants in KCNB1, encoding the voltage-gated potassium channel KV 2.1, are associated with developmental and epileptic encephalopathy (DEE). Previous functional studies on a limited number of KCNB1 variants indicated a range of molecular mechanisms by which variants affect channel function, including loss of voltage sensitivity, loss of ion selectivity, and reduced cell-surface expression. METHODS We evaluated a series of 17 KCNB1 variants associated with DEE or other neurodevelopmental disorders (NDDs) to rapidly ascertain channel dysfunction using high-throughput functional assays. Specifically, we investigated the biophysical properties and cell-surface expression of variant KV 2.1 channels expressed in heterologous cells using high-throughput automated electrophysiology and immunocytochemistry-flow cytometry. RESULTS Pathogenic variants exhibited diverse functional defects, including altered current density and shifts in the voltage dependence of activation and/or inactivation, as homotetramers or when coexpressed with wild-type KV 2.1. Quantification of protein expression also identified variants with reduced total KV 2.1 expression or deficient cell-surface expression. INTERPRETATION Our study establishes a platform for rapid screening of KV 2.1 functional defects caused by KCNB1 variants associated with DEE and other NDDs. This will aid in establishing KCNB1 variant pathogenicity and the mechanism of dysfunction, which will enable targeted strategies for therapeutic intervention based on molecular phenotype. ANN NEUROL 2019;86:899-912.
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Affiliation(s)
- Seok Kyu Kang
- Departments of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL
| | - Carlos G Vanoye
- Departments of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL
| | - Sunita N Misra
- Departments of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL.,Departments of Pediatrics, Northwestern University Feinberg School of Medicine, Chicago, IL.,Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, IL
| | - Dennis M Echevarria
- Departments of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL
| | - Jeffrey D Calhoun
- Departments of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL
| | - John B O'Connor
- Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, IL
| | - Katarina L Fabre
- Departments of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL
| | | | - Laurie Demmer
- Department of Pediatrics, Atrium Health's Levine Children's Hospital, Charlotte, NC
| | - Paula Goldenberg
- Medical Genetics, Massachusetts General Hospital for Children, Harvard Medical School, Boston, MA
| | - Lauren E Grote
- Division of Clinical Genetics, Children's Mercy Hospital, Kansas City, MO.,University of Missouri-Kansas City School of Medicine, Kansas City, MO
| | - Isabelle Thiffault
- University of Missouri-Kansas City School of Medicine, Kansas City, MO.,Center for Pediatric Genomic Medicine, Children's Mercy Hospital, Kansas City, MO.,Department of Pathology and Laboratory Medicine, Children's Mercy Hospital, Kansas City, MO
| | - Carol Saunders
- University of Missouri-Kansas City School of Medicine, Kansas City, MO.,Center for Pediatric Genomic Medicine, Children's Mercy Hospital, Kansas City, MO.,Department of Pathology and Laboratory Medicine, Children's Mercy Hospital, Kansas City, MO
| | | | - Ali Torkamani
- Scripps Translational Science Institute and Scripps Research Institute, La Jolla, CA
| | - Jasper van der Smagt
- Department of Genetics, University Medical Center Utrecht, Utrecht, the Netherlands
| | - Koen van Gassen
- Department of Genetics, University Medical Center Utrecht, Utrecht, the Netherlands
| | - Robert P Carson
- Monroe Carell Jr Children's Hospital at Vanderbilt, Nashville, TN
| | - Jullianne Diaz
- Rare Disease Institute, Children's National Medical Center, Washington, DC
| | - Eyby Leon
- Rare Disease Institute, Children's National Medical Center, Washington, DC
| | - Joseph E Jacher
- Division of Pediatric Genetics, Metabolism, and Genomic Medicine, University of Michigan, Ann Arbor, MI
| | - Mark C Hannibal
- Division of Pediatric Genetics, Metabolism, and Genomic Medicine, University of Michigan, Ann Arbor, MI
| | - Jessica Litwin
- University of California, San Francisco Benioff Children's Hospital, San Francisco, CA
| | | | | | - Bryan Lynch
- Department of Paediatric Neurology and Clinical Neurophysiology, Children's University Hospital, Dublin, Ireland
| | - Annapurna Poduri
- Epilepsy Genetics Program, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA
| | - Eric D Marsh
- Division of Child Neurology, Children's Hospital of Philadelphia, Philadelphia, PA
| | - Ethan M Goldberg
- Division of Child Neurology, Children's Hospital of Philadelphia, Philadelphia, PA
| | - John J Millichap
- Departments of Pediatrics, Northwestern University Feinberg School of Medicine, Chicago, IL.,Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, IL.,Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL
| | - Alfred L George
- Departments of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL
| | - Jennifer A Kearney
- Departments of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL
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The Novel Direct Modulatory Effects of Perampanel, an Antagonist of AMPA Receptors, on Voltage-Gated Sodium and M-type Potassium Currents. Biomolecules 2019; 9:biom9100638. [PMID: 31652643 PMCID: PMC6843791 DOI: 10.3390/biom9100638] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Accepted: 10/20/2019] [Indexed: 12/17/2022] Open
Abstract
Perampanel (PER) is a selective blocker of AMPA receptors showing efficacy in treating various epileptic disorders including brain tumor-related epilepsy and also potential in treating motor neuron disease. However, besides its inhibition of AMPA-induced currents, whether PER has any other direct ionic effects in different types of neurons remains largely unknown. We investigated the effects of PER and related compounds on ionic currents in different types of cells, including hippocampal mHippoE-14 neurons, motor neuron-like NSC-34 cells and U87 glioma cells. We found that PER differentially and effectively suppressed the amplitude of voltage-gated Na+ currents (INa) in mHippoE-14 cells. The IC50 values required to inhibit peak and late INa were 4.12 and 0.78 μM, respectively. PER attenuated tefluthrin-induced increases in both amplitude and deactivating time constant of INa. Importantly, PER also inhibited the amplitude of M-type K+ currents (IK(M)) with an IC50 value of 0.92 μM. The suppression of IK(M) was attenuated by the addition of flupirtine or ZnCl2 but not by L-quisqualic acid or sorafenib. Meanwhile, in cell-attached configuration, PER (3 μM) decreased the activity of M-type K+ channels with no change in single-channel conductance but shifting the activation curve along the voltage axis in a rightward direction. Supportively, PER suppressed IK(M) in NSC-34 cells and INa in U87 glioma cells. The inhibitory effects of PER on both INa and IK(M), independent of its antagonistic effect on AMPA receptors, may be responsible for its wide-spectrum of effects observed in neurological clinical practice.
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39
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Jędrychowska J, Korzh V. Kv2.1 voltage-gated potassium channels in developmental perspective. Dev Dyn 2019; 248:1180-1194. [PMID: 31512327 DOI: 10.1002/dvdy.114] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Revised: 09/01/2019] [Accepted: 09/03/2019] [Indexed: 11/11/2022] Open
Abstract
Kv2.1 voltage-gated potassium channels consist of two types of α-subunits: (a) electrically-active Kcnb1 α-subunits and (b) silent or modulatory α-subunits plus β-subunits that, similar to silent α-subunits, also regulate electrically-active subunits. Voltage-gated potassium channels were traditionally viewed, mainly by electrophysiologists, as regulators of the electrical activity of the plasma membrane in excitable cells, a role that is performed by transmembrane protein domains of α-subunits that form the electric pore. Genetic studies revealed a role for this region of α-subunits of voltage-gated potassium channels in human neurodevelopmental disorders, such as epileptic encephalopathy. The N- and C-terminal domains of α-subunits interact to form the cytoplasmic subunit of heterotetrameric potassium channels that regulate electric pores. Subsequent animal studies revealed the developmental functions of Kcnb1-containing voltage-gated potassium channels and illustrated their role during brain development and reproduction. These functions of potassium channels are discussed in this review in the context of regulatory interactions between electrically-active and regulatory subunits.
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Affiliation(s)
- Justyna Jędrychowska
- International Institute of Molecular and Cell Biology in Warsaw, Warsaw, Poland.,Postgraduate School of Molecular Medicine, Warsaw Medical University, Warsaw, Poland
| | - Vladimir Korzh
- International Institute of Molecular and Cell Biology in Warsaw, Warsaw, Poland
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40
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Bar C, Barcia G, Jennesson M, Le Guyader G, Schneider A, Mignot C, Lesca G, Breuillard D, Montomoli M, Keren B, Doummar D, Billette de Villemeur T, Afenjar A, Marey I, Gerard M, Isnard H, Poisson A, Dupont S, Berquin P, Meyer P, Genevieve D, De Saint Martin A, El Chehadeh S, Chelly J, Guët A, Scalais E, Dorison N, Myers CT, Mefford HC, Howell KB, Marini C, Freeman JL, Nica A, Terrone G, Sekhara T, Lebre A, Odent S, Sadleir LG, Munnich A, Guerrini R, Scheffer IE, Kabashi E, Nabbout R. Expanding the genetic and phenotypic relevance of
KCNB1
variants in developmental and epileptic encephalopathies: 27 new patients and overview of the literature. Hum Mutat 2019; 41:69-80. [DOI: 10.1002/humu.23915] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Revised: 08/28/2019] [Accepted: 09/09/2019] [Indexed: 12/28/2022]
Affiliation(s)
- Claire Bar
- Department of Pediatric Neurology, Reference Centre for Rare EpilepsiesHôpital Necker‐Enfants MaladesParis France
- Imagine institute, laboratory of Translational Research for Neurological Disorders, INSERM UMR 1163Imagine InstituteParis France
- Université Paris Descartes‐Sorbonne Paris CitéParis France
| | - Giulia Barcia
- Imagine institute, laboratory of Translational Research for Neurological Disorders, INSERM UMR 1163Imagine InstituteParis France
- Université Paris Descartes‐Sorbonne Paris CitéParis France
- Department of genetics, Necker Enfants Malades hospitalAssistance Publique‐Hôpitaux de ParisParis France
| | | | - Gwenaël Le Guyader
- Department of geneticsUniversity hospital PoitiersPoitiers Cedex France
- EA3808‐NEUVACOD Unité Neurovasculaire et Troubles Cognitifs, Pôle Biologie SantéUniversité de PoitiersPoitiers France
| | - Amy Schneider
- Department of Medicine, Epilepsy Research Centre, Austin HealthThe University of MelbourneHeidelberg Victoria Australia
| | - Cyril Mignot
- Institut du Cerveau et de la Moelle épinière, INSERM, U 1127, CNRS UMR 7225Sorbonne Universités UPMC Univ Paris 06 UMR S 1127 Paris France
- Département de Génétique et de Cytogénétique, Centre de Reference Déficience Intellectuelle de Causes Rares, APHP, Hôpital Pitié‐SalpêtrièreGRC UPMC (Déficience Intellectuelle et Autisme)Paris France
| | - Gaetan Lesca
- Department of geneticsHospices Civils de LyonLyon France
- Neurosciences centre of Lyon, INSERM U1028, UMR CNRS 5292Université Claude Bernard Lyon 1Bron Cedex France
| | - Delphine Breuillard
- Department of Pediatric Neurology, Reference Centre for Rare EpilepsiesHôpital Necker‐Enfants MaladesParis France
| | - Martino Montomoli
- Pediatric Neurology, Neurogenetics and Neurobiology Unit and Laboratories, Department of Neuroscience, A Meyer Children's HospitalUniversity of FlorenceFlorence Italy
| | - Boris Keren
- Département de Génétique et de Cytogénétique, Centre de Reference Déficience Intellectuelle de Causes Rares, APHP, Hôpital Pitié‐SalpêtrièreGRC UPMC (Déficience Intellectuelle et Autisme)Paris France
| | - Diane Doummar
- Department of Pediatric Neurology, Hôpital Armand TrousseauAP‐HPParis France
| | | | - Alexandra Afenjar
- Département de Génétique et Embryologie Médicale, Pathologies Congénitales du Cervelet‐LeucoDystrophies, Centre de Référence déficiences intellectuelles de causes rares, AP‐HP, Hôpital Armand Trousseau, GRC n°19Sorbonne UniversitéParis France
| | - Isabelle Marey
- Département de Génétique et de Cytogénétique, Centre de Reference Déficience Intellectuelle de Causes Rares, APHP, Hôpital Pitié‐SalpêtrièreGRC UPMC (Déficience Intellectuelle et Autisme)Paris France
| | | | | | - Alice Poisson
- Reference Center for Diagnosis and Management of Genetic Psychiatric Disorders, Centre Hospitalier le Vinatier and EDR‐Psy TeamCentre National de la Recherche Scientifique & Lyon 1 Claude Bernard UniversityVilleurbanne France
| | - Sophie Dupont
- Institut du Cerveau et de la Moelle épinière, INSERM, U 1127, CNRS UMR 7225Sorbonne Universités UPMC Univ Paris 06 UMR S 1127 Paris France
- Epileptology and Rehabilitation department, GH Pitie‐Salpêtrière‐Charles FoixAP‐HPParis France
| | - Patrick Berquin
- Department of pediatric neurology Amiens‐Picardie university hospitalUniversité de Picardie Jules VerneAmiens France
| | - Pierre Meyer
- Department of pediatric neurologyMontpellier university hospitalMontpellier France
- PhyMedExp, U1046 INSERMUMR9214 CNRSMontpellier France
| | - David Genevieve
- Service de génétique clinique et du Département de Génétique Médicale, Maladies Rares et Médecine Personnalisée, Centre de référence maladies rares anomalies du développementCHU MontpellierMontpellier France
| | - Anne De Saint Martin
- Department of Pediatric NeurologyStrasbourg University HospitalStrasbourg France
| | - Salima El Chehadeh
- Department of genetics, Hôpital de HautepierreHôpitaux Universitaires de StrasbourgStrasbourg France
| | - Jamel Chelly
- Department of genetics, Hôpital de HautepierreHôpitaux Universitaires de StrasbourgStrasbourg France
| | - Agnès Guët
- Department of PediatricLouis‐Mourier HospitalColombes France
| | - Emmanuel Scalais
- Department of Pediatric Neurology, Centre Hospitalier de LuxembourgLuxembourg CityLuxembourg City Luxembourg
| | - Nathalie Dorison
- Department of pediatric NeurosurgeryRothschild Foundation HospitalParis France
| | - Candace T. Myers
- Department of PediatricsUniversity of WashingtonSeattle Washington
| | - Heather C. Mefford
- Department of Pediatrics, Division of Genetic MedicineUniversity of WashingtonSeattle Washington
| | - Katherine B. Howell
- Departments of Neurology and Paediatrics, Royal Children's HospitalUniversity of MelbourneMelbourne Victoria Australia
- Murdoch Children's Research InstituteMelbourne Victoria Australia
| | - Carla Marini
- Pediatric Neurology, Neurogenetics and Neurobiology Unit and Laboratories, Department of Neuroscience, A Meyer Children's HospitalUniversity of FlorenceFlorence Italy
| | - Jeremy L. Freeman
- Departments of Neurology and Paediatrics, Royal Children's HospitalUniversity of MelbourneMelbourne Victoria Australia
- Murdoch Children's Research InstituteMelbourne Victoria Australia
| | - Anca Nica
- Department of Neurology, Center for Clinical Research (CIC 1414)Rennes University HospitalRennes France
| | - Gaetano Terrone
- Department of Translational Medical Sciences, Section of Pediatrics‐Child Neurology UnitFederico II UniversityNaples Italy
| | - Tayeb Sekhara
- Department of Pediatric NeurologyC.H.I.R.E.CBrussels Belgium
| | - Anne‐Sophie Lebre
- Department of genetics, Maison Blanche hospitalUniversity hospital, ReimsReims France
| | - Sylvie Odent
- Reference Centre for Rare Developmental AbnormalitiesCLAD‐Ouest, CHU RennesRennes France
- Institute of genetics and developmentCNRS UMR 6290, Rennes universityRennes France
| | - Lynette G. Sadleir
- Department of Paediatrics and Child HealthUniversity of OtagoWellington New Zealand
| | - Arnold Munnich
- Université Paris Descartes‐Sorbonne Paris CitéParis France
- Department of genetics, Necker Enfants Malades hospitalAssistance Publique‐Hôpitaux de ParisParis France
| | - Renzo Guerrini
- Pediatric Neurology, Neurogenetics and Neurobiology Unit and Laboratories, Department of Neuroscience, A Meyer Children's HospitalUniversity of FlorenceFlorence Italy
| | - Ingrid E. Scheffer
- Department of Medicine, Epilepsy Research Centre, Austin HealthThe University of MelbourneHeidelberg Victoria Australia
- Departments of Neurology and Paediatrics, Royal Children's HospitalUniversity of MelbourneMelbourne Victoria Australia
- The Florey Institute of Neurosciences and Mental HealthHeidelberg Victoria Australia
| | - Edor Kabashi
- Imagine institute, laboratory of Translational Research for Neurological Disorders, INSERM UMR 1163Imagine InstituteParis France
- Université Paris Descartes‐Sorbonne Paris CitéParis France
| | - Rima Nabbout
- Department of Pediatric Neurology, Reference Centre for Rare EpilepsiesHôpital Necker‐Enfants MaladesParis France
- Imagine institute, laboratory of Translational Research for Neurological Disorders, INSERM UMR 1163Imagine InstituteParis France
- Université Paris Descartes‐Sorbonne Paris CitéParis France
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41
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Jacobson DA, Shyng SL. Ion Channels of the Islets in Type 2 Diabetes. J Mol Biol 2019; 432:1326-1346. [PMID: 31473158 DOI: 10.1016/j.jmb.2019.08.014] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Revised: 08/19/2019] [Accepted: 08/21/2019] [Indexed: 02/06/2023]
Abstract
Ca2+ is an essential signal for pancreatic β-cell function. Ca2+ plays critical roles in numerous β-cell pathways such as insulin secretion, transcription, metabolism, endoplasmic reticulum function, and the stress response. Therefore, β-cell Ca2+ handling is tightly controlled. At the plasma membrane, Ca2+ entry primarily occurs through voltage-dependent Ca2+ channels. Voltage-dependent Ca2+ channel activity is dependent on orchestrated fluctuations in the plasma membrane potential or voltage, which are mediated via the activity of many ion channels. During the pathogenesis of type 2 diabetes the β-cell is exposed to stressful conditions, which result in alterations of Ca2+ handling. Some of the changes in β-cell Ca2+ handling that occur under stress result from perturbations in ion channel activity, expression or localization. Defective Ca2+ signaling in the diabetic β-cell alters function, limits insulin secretion and exacerbates hyperglycemia. In this review, we focus on the β-cell ion channels that control Ca2+ handling and how they impact β-cell dysfunction in type 2 diabetes.
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Affiliation(s)
- David A Jacobson
- Department of Molecular Physiology and Biophysics, Vanderbilt University, 7415 MRB4 (Langford), 2213 Garland Avenue, Nashville, TN 37232, USA.
| | - Show-Ling Shyng
- Department of Biochemistry and Molecular Biology, Oregon Health & Science University, L224, MRB 624, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA.
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42
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Romer SH, Deardorff AS, Fyffe REW. A molecular rheostat: Kv2.1 currents maintain or suppress repetitive firing in motoneurons. J Physiol 2019; 597:3769-3786. [DOI: 10.1113/jp277833] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Accepted: 05/29/2019] [Indexed: 12/26/2022] Open
Affiliation(s)
- Shannon H. Romer
- Neuroscience, Cell Biology & PhysiologyBoonshoft School of MedicineWright State University Fairborn OH 45435 USA
- Oak Ridge Institute for Science and EducationEnvironmental Health Effects LaboratoryNavy Medical Research Unit‐DaytonWright‐Patterson Air Force Base OH 45433 USA
| | - Adam S. Deardorff
- Neuroscience, Cell Biology & PhysiologyBoonshoft School of MedicineWright State University Fairborn OH 45435 USA
- Neurology, Boonshoft School of MedicineWright State University Dayton OH 45409 USA
| | - Robert E. W. Fyffe
- Neuroscience, Cell Biology & PhysiologyBoonshoft School of MedicineWright State University Fairborn OH 45435 USA
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43
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Dong J, Williams N, Cerrone M, Borck C, Wang D, Zhou B, Eng LS, Subbotina E, Um SY, Lin Y, Ruiter K, Rojas L, Coetzee WA, Sampson BA, Tang Y. Molecular autopsy: using the discovery of a novel de novo pathogenic variant in the KCNH2 gene to inform healthcare of surviving family. Heliyon 2018; 4:e01015. [PMID: 30582040 PMCID: PMC6288419 DOI: 10.1016/j.heliyon.2018.e01015] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Revised: 10/24/2018] [Accepted: 12/04/2018] [Indexed: 01/23/2023] Open
Abstract
Background Molecular testing of the deceased (Molecular Autopsy) is an overlooked area in the United States healthcare system and is not covered by medical insurance, leading to ineffective care for surviving families of thousands of sudden unexpected natural deaths each year. We demonstrated the precision management of surviving family members through the discovery of a novel de novo pathogenic variant in a decedent. Methods Forensic investigation and molecular autopsy were performed on an 18-year-old female who died suddenly and unexpectedly. Co-segregation family study of the first-degree relatives and functional characterization of the variant were conducted. Findings We identified a novel nonsense variant, NP_000229.1:p.Gln1068Ter, in the long QT syndrome type II gene KCNH2 in the decedent. This finding correlated with her ante-mortem electrocardiograms. Patch clamp functional studies using transfected COS-7 cells show that hERG-ΔQ1068 has a mixed phenotype, with both gain- (negative voltage shift of steady-state activation curve, the positive shift of the steady-state inactivation curve, and accelerated activation) and loss-of function (reduced current density, reduced surface expression and accelerated deactivation) hallmarks. Loss of cumulative activation during rapid pacing demonstrates that the loss-of-function phenotype predominates. The wild-type channel did not rescue the hERG-ΔQ1068 defects, demonstrating haploinsufficiency of the heterozygous state. Targeted variant testing in the family showed that the variant in KCNH2 arose de novo, which eliminated the need for exhaustive genome testing and annual cardiac follow-up for the parents and four siblings. Interpretation Molecular testing enables accurate determination of natural causes of death and precision care of the surviving family members in a time and cost-saving manner. We advocate for molecular autopsy being included under the healthcare coverage in US.
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Affiliation(s)
- Jingyun Dong
- Department of Pediatrics, NYU School of Medicine, USA.,Department of Biochemistry and Molecular Pharmacology, NYU School of Medicine, USA.,Department of Physiology and Neurosciences, NYU School of Medicine, USA
| | - Nori Williams
- Molecular Genetics Laboratory, New York City Office of Chief Medical Examiner, USA
| | - Marina Cerrone
- Cardiovascular Genetics Program, Leon H Charney Division of Cardiology, NYU School of Medicine, NY, USA
| | - Christopher Borck
- Department of Pathology, New York City Office of Chief Medical Examiner, USA
| | - Dawei Wang
- Molecular Genetics Laboratory, New York City Office of Chief Medical Examiner, USA
| | - Bo Zhou
- Molecular Genetics Laboratory, New York City Office of Chief Medical Examiner, USA
| | - Lucy S Eng
- Molecular Genetics Laboratory, New York City Office of Chief Medical Examiner, USA
| | - Ekaterina Subbotina
- Department of Pediatrics, NYU School of Medicine, USA.,Department of Biochemistry and Molecular Pharmacology, NYU School of Medicine, USA.,Department of Physiology and Neurosciences, NYU School of Medicine, USA
| | - Sung Yon Um
- Molecular Genetics Laboratory, New York City Office of Chief Medical Examiner, USA
| | - Ying Lin
- Molecular Genetics Laboratory, New York City Office of Chief Medical Examiner, USA
| | - Kevin Ruiter
- Molecular Genetics Laboratory, New York City Office of Chief Medical Examiner, USA
| | - Lisa Rojas
- Molecular Genetics Laboratory, New York City Office of Chief Medical Examiner, USA
| | - William A Coetzee
- Department of Pediatrics, NYU School of Medicine, USA.,Department of Biochemistry and Molecular Pharmacology, NYU School of Medicine, USA.,Department of Physiology and Neurosciences, NYU School of Medicine, USA
| | - Barbara A Sampson
- Department of Pathology, New York City Office of Chief Medical Examiner, USA
| | - Yingying Tang
- Molecular Genetics Laboratory, New York City Office of Chief Medical Examiner, USA
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44
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Kirmiz M, Palacio S, Thapa P, King AN, Sack JT, Trimmer JS. Remodeling neuronal ER-PM junctions is a conserved nonconducting function of Kv2 plasma membrane ion channels. Mol Biol Cell 2018; 29:2410-2432. [PMID: 30091655 PMCID: PMC6233057 DOI: 10.1091/mbc.e18-05-0337] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The endoplasmic reticulum (ER) and plasma membrane (PM) form junctions crucial to ion and lipid signaling and homeostasis. The Kv2.1 ion channel is localized at ER–PM junctions in brain neurons and is unique among PM proteins in its ability to remodel these specialized membrane contact sites. Here, we show that this function is conserved between Kv2.1 and Kv2.2, which differ in their biophysical properties, modulation, and cellular expression. Kv2.2 ER–PM junctions are present at sites deficient in the actin cytoskeleton, and disruption of the actin cytoskeleton affects their spatial organization. Kv2.2-containing ER–PM junctions overlap with those formed by canonical ER–PM tethers. The ability of Kv2 channels to remodel ER–PM junctions is unchanged by point mutations that eliminate their ion conduction but eliminated by point mutations within the Kv2-specific proximal restriction and clustering (PRC) domain that do not impact their ion channel function. The highly conserved PRC domain is sufficient to transfer the ER–PM junction–remodeling function to another PM protein. Last, brain neurons in Kv2 double-knockout mice have altered ER–PM junctions. Together, these findings demonstrate a conserved in vivo function for Kv2 family members in remodeling neuronal ER–PM junctions that is distinct from their canonical role as ion-conducting channels shaping neuronal excitability.
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Affiliation(s)
- Michael Kirmiz
- Department of Neurobiology, Physiology, and Behavior, University of California, Davis, Davis, CA 95616
| | - Stephanie Palacio
- Department of Neurobiology, Physiology, and Behavior, University of California, Davis, Davis, CA 95616
| | - Parashar Thapa
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA 95616
| | - Anna N King
- Department of Neurobiology, Physiology, and Behavior, University of California, Davis, Davis, CA 95616
| | - Jon T Sack
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA 95616.,Department of Anesthesiology and Pain Medicine, University of California, Davis, Davis, CA 95616
| | - James S Trimmer
- Department of Neurobiology, Physiology, and Behavior, University of California, Davis, Davis, CA 95616.,Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA 95616
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45
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Identification of VAPA and VAPB as Kv2 Channel-Interacting Proteins Defining Endoplasmic Reticulum-Plasma Membrane Junctions in Mammalian Brain Neurons. J Neurosci 2018; 38:7562-7584. [PMID: 30012696 DOI: 10.1523/jneurosci.0893-18.2018] [Citation(s) in RCA: 85] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Revised: 06/01/2018] [Accepted: 07/07/2018] [Indexed: 11/21/2022] Open
Abstract
Membrane contacts between endoplasmic reticulum (ER) and plasma membrane (PM), or ER-PM junctions, are ubiquitous in eukaryotic cells and are platforms for lipid and calcium signaling and homeostasis. Recent studies have revealed proteins crucial to the formation and function of ER-PM junctions in non-neuronal cells, but little is known of the ER-PM junctions prominent in aspiny regions of mammalian brain neurons. The Kv2.1 voltage-gated potassium channel is abundantly clustered at ER-PM junctions in brain neurons and is the first PM protein that functions to organize ER-PM junctions. However, the molecular mechanism whereby Kv2.1 localizes to and remodels these junctions is unknown. We used affinity immunopurification and mass spectrometry-based proteomics on brain samples from male and female WT and Kv2.1 KO mice and identified the resident ER vesicle-associated membrane protein-associated proteins isoforms A and B (VAPA and VAPB) as prominent Kv2.1-associated proteins. Coexpression with Kv2.1 or its paralog Kv2.2 was sufficient to recruit VAPs to ER-PM junctions. Multiplex immunolabeling revealed colocalization of Kv2.1 and Kv2.2 with endogenous VAPs at ER-PM junctions in brain neurons from male and female mice in situ and in cultured rat hippocampal neurons, and KO of VAPA in mammalian cells reduces Kv2.1 clustering. The association of VAPA with Kv2.1 relies on a "two phenylalanines in an acidic tract" (FFAT) binding domain on VAPA and a noncanonical phosphorylation-dependent FFAT motif comprising the Kv2-specific clustering or PRC motif. These results suggest that Kv2.1 localizes to and organizes neuronal ER-PM junctions through an interaction with VAPs.SIGNIFICANCE STATEMENT Our study identified the endoplasmic reticulum (ER) proteins vesicle-associated membrane protein-associated proteins isoforms A and B (VAPA and VAPB) as proteins copurifying with the plasma membrane (PM) Kv2.1 ion channel. We found that expression of Kv2.1 recruits VAPs to ER-PM junctions, specialized membrane contact sites crucial to distinct aspects of cell function. We found endogenous VAPs at Kv2.1-mediated ER-PM junctions in brain neurons and other mammalian cells and that knocking out VAPA expression disrupts Kv2.1 clustering. We identified domains of VAPs and Kv2.1 necessary and sufficient for their association at ER-PM junctions. Our study suggests that Kv2.1 expression in the PM can affect ER-PM junctions via its phosphorylation-dependent association to ER-localized VAPA and VAPB.
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46
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Evaluating the pathogenic potential of genes with de novo variants in epileptic encephalopathies. Genet Med 2018; 21:17-27. [PMID: 29895856 PMCID: PMC6752304 DOI: 10.1038/s41436-018-0011-y] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2017] [Accepted: 03/20/2018] [Indexed: 01/08/2023] Open
Abstract
Epileptic encephalopathies comprise a group of catastrophic epilepsies with heterogeneous genetic etiology. Although next-generation sequencing techniques can reveal a number of de novo variants in epileptic encephalopathies, evaluating the pathogenicity of these variants can be challenging. Determining the pathogenic potential of genes in epileptic encephalopathies is critical before evaluating the pathogenicity of variants identified in an individual. We reviewed de novo variants in epileptic encephalopathies, including their genotypes and functional consequences. We then evaluated the pathogenic potential of genes, with the following additional considerations: (1) recurrence of variants in unrelated cases, (2) information of previously defined phenotypes, and (3) data from genetic experimental studies. Genes related to epileptic encephalopathy revealed pathogenicity with distinct functional alterations, i.e., either a gain of function or loss of function in the majority; however, several genes warranted further study to confirm their pathogenic potential. Whether a gene was associated with distinct phenotype, the genotype (or functional alteration)-–phenotype correlation, and quantitative correlation between genetic impairment and phenotype severity were suggested to be specific evidence in determining the pathogenic role of genes. Data from epileptic encephalopathy-related genes would be helpful in outlining guidelines for evaluating the pathogenic potential of genes in other genetic disorders.
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47
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Schönewolf-Greulich B, Bisgaard AM, Møller R, Dunø M, Brøndum-Nielsen K, Kaur S, Van Bergen N, Lunke S, Eggers S, Jespersgaard C, Christodoulou J, Tümer Z. Clinician’s guide to genes associated with Rett-like phenotypes-Investigation of a Danish cohort and review of the literature. Clin Genet 2018; 95:221-230. [DOI: 10.1111/cge.13153] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2017] [Revised: 10/04/2017] [Accepted: 10/05/2017] [Indexed: 12/16/2022]
Affiliation(s)
- B. Schönewolf-Greulich
- Center for Rett Syndrome, Kennedy Center, Department of Paediatrics; Copenhagen University Hospital, Rigshospitalet; Copenhagen Denmark
- Applied Human Molecular Genetics, Kennedy Center, Department of Clinical Genetics; Copenhagen University Hospital, Rigshospitalet; Copenhagen Denmark
| | - A-M. Bisgaard
- Center for Rett Syndrome, Kennedy Center, Department of Paediatrics; Copenhagen University Hospital, Rigshospitalet; Copenhagen Denmark
| | - R.S. Møller
- Danish Epilepsy Centre; Dianalund Denmark
- Institute for Regional Health Services; University of Southern Denmark; Odense Denmark
| | - M. Dunø
- Department of Clinical Genetics; Copenhagen University Hospital, Rigshospitalet; Copenhagen Denmark
| | - K. Brøndum-Nielsen
- Department of Clinical Genetics; Copenhagen University Hospital, Rigshospitalet; Copenhagen Denmark
| | - S. Kaur
- Neurodevelopmental Genomics Research Group; Murdoch Children's Research Institute; Melbourne Australia
- Department of Paediatrics; Melbourne Medical School, University of Melbourne; Melbourne Australia
| | - N.J. Van Bergen
- Neurodevelopmental Genomics Research Group; Murdoch Children's Research Institute; Melbourne Australia
- Department of Paediatrics; Melbourne Medical School, University of Melbourne; Melbourne Australia
| | - S. Lunke
- Translational Genomics Unit; Murdoch Children’s Research Institute; Melbourne Australia
| | - S. Eggers
- Translational Genomics Unit; Murdoch Children’s Research Institute; Melbourne Australia
| | - C. Jespersgaard
- Applied Human Molecular Genetics, Kennedy Center, Department of Clinical Genetics; Copenhagen University Hospital, Rigshospitalet; Copenhagen Denmark
| | - J. Christodoulou
- Neurodevelopmental Genomics Research Group; Murdoch Children's Research Institute; Melbourne Australia
- Department of Paediatrics; Melbourne Medical School, University of Melbourne; Melbourne Australia
| | - Z. Tümer
- Applied Human Molecular Genetics, Kennedy Center, Department of Clinical Genetics; Copenhagen University Hospital, Rigshospitalet; Copenhagen Denmark
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48
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Monogenic disorders that mimic the phenotype of Rett syndrome. Neurogenetics 2018; 19:41-47. [PMID: 29322350 DOI: 10.1007/s10048-017-0535-3] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Revised: 12/17/2017] [Accepted: 12/21/2017] [Indexed: 10/18/2022]
Abstract
Rett syndrome (RTT) is caused by mutations in methyl-CpG-binding protein 2 (MECP2), but defects in a handful of other genes (e.g., CDKL5, FOXG1, MEF2C) can lead to presentations that resemble, but do not completely mirror, classical RTT. In this study, we attempted to identify other monogenic disorders that share features with RTT. We performed a retrospective chart review on n = 319 patients who had undergone clinical whole exome sequencing (WES) for further etiological evaluation of neurodevelopmental diagnoses that remained unexplained despite extensive prior workup. From this group, we characterized those who (1) possessed features that were compatible with RTT based on clinical judgment, (2) subsequently underwent MECP2 sequencing and/or MECP2 deletion/duplication analysis with negative results, and (3) ultimately arrived at a diagnosis other than RTT with WES. n = 7 patients had clinical features overlapping RTT with negative MECP2 analysis but positive WES providing a diagnosis. These seven patients collectively possessed pathogenic variants in six different genes: two in KCNB1 and one each in FOXG1, IQSEC2, MEIS2, TCF4, and WDR45. n = 2 (both with KCNB1 variants) fulfilled criteria for atypical RTT. RTT-associated features included the following: loss of hand or language skills (n = 3; IQSEC2, KCNB1 x 2); disrupted sleep (n = 4; KNCB1, MEIS2, TCF4, WDR45); stereotyped hand movements (n = 5; FOXG1, KNCB1 x 2, MEIS2, TCF4); bruxism (n = 3; KCNB1 x 2; TCF4); and hypotonia (n = 7). Clinically based diagnoses can be misleading, evident by the increasing number of genetic conditions associated with features of RTT with negative MECP2 mutations.
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49
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Oyrer J, Maljevic S, Scheffer IE, Berkovic SF, Petrou S, Reid CA. Ion Channels in Genetic Epilepsy: From Genes and Mechanisms to Disease-Targeted Therapies. Pharmacol Rev 2018; 70:142-173. [PMID: 29263209 DOI: 10.1124/pr.117.014456] [Citation(s) in RCA: 163] [Impact Index Per Article: 27.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Accepted: 10/02/2017] [Indexed: 12/19/2022] Open
Abstract
Epilepsy is a common and serious neurologic disease with a strong genetic component. Genetic studies have identified an increasing collection of disease-causing genes. The impact of these genetic discoveries is wide reaching-from precise diagnosis and classification of syndromes to the discovery and validation of new drug targets and the development of disease-targeted therapeutic strategies. About 25% of genes identified in epilepsy encode ion channels. Much of our understanding of disease mechanisms comes from work focused on this class of protein. In this study, we review the genetic, molecular, and physiologic evidence supporting the pathogenic role of a number of different voltage- and ligand-activated ion channels in genetic epilepsy. We also review proposed disease mechanisms for each ion channel and highlight targeted therapeutic strategies.
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Affiliation(s)
- Julia Oyrer
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Melbourne, Australia (J.O., S.M., I.E.S., S.P., C.A.R.); Department of Medicine, Austin Health, University of Melbourne, Heidelberg West, Melbourne, Australia (I.E.S., S.F.B.); and Department of Paediatrics, University of Melbourne, Royal Children's Hospital, Melbourne, Australia (I.E.S.)
| | - Snezana Maljevic
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Melbourne, Australia (J.O., S.M., I.E.S., S.P., C.A.R.); Department of Medicine, Austin Health, University of Melbourne, Heidelberg West, Melbourne, Australia (I.E.S., S.F.B.); and Department of Paediatrics, University of Melbourne, Royal Children's Hospital, Melbourne, Australia (I.E.S.)
| | - Ingrid E Scheffer
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Melbourne, Australia (J.O., S.M., I.E.S., S.P., C.A.R.); Department of Medicine, Austin Health, University of Melbourne, Heidelberg West, Melbourne, Australia (I.E.S., S.F.B.); and Department of Paediatrics, University of Melbourne, Royal Children's Hospital, Melbourne, Australia (I.E.S.)
| | - Samuel F Berkovic
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Melbourne, Australia (J.O., S.M., I.E.S., S.P., C.A.R.); Department of Medicine, Austin Health, University of Melbourne, Heidelberg West, Melbourne, Australia (I.E.S., S.F.B.); and Department of Paediatrics, University of Melbourne, Royal Children's Hospital, Melbourne, Australia (I.E.S.)
| | - Steven Petrou
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Melbourne, Australia (J.O., S.M., I.E.S., S.P., C.A.R.); Department of Medicine, Austin Health, University of Melbourne, Heidelberg West, Melbourne, Australia (I.E.S., S.F.B.); and Department of Paediatrics, University of Melbourne, Royal Children's Hospital, Melbourne, Australia (I.E.S.)
| | - Christopher A Reid
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Melbourne, Australia (J.O., S.M., I.E.S., S.P., C.A.R.); Department of Medicine, Austin Health, University of Melbourne, Heidelberg West, Melbourne, Australia (I.E.S., S.F.B.); and Department of Paediatrics, University of Melbourne, Royal Children's Hospital, Melbourne, Australia (I.E.S.)
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50
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Aboutorabi A, Naderi N, Gholami pourbadie H, Zolfagharian H, Vatanpour H. The Effects of Buthotus schach Scorpion Venom on Electrophysiological Properties of Magnocellular Neurons of Rat Supraoptic Nucleus. IRANIAN JOURNAL OF PHARMACEUTICAL RESEARCH : IJPR 2018; 17:184-192. [PMID: 29755550 PMCID: PMC5937089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Bothutous Schach (BS) scorpion venom consists of several polypeptides that could modulate ion channels. In this study, the effects of BS crude venom on passive and active electrophysiological properties of rat neurons in supraoptic nucleus (SON) of hypothalamus was investigated using whole-cell patch clamp technique. The results showed that bath application of BS venom produced significant change in passive properties of SON neurons, namely a decrease in resting membrane potential and an increase in input resistance of the cells. Also, significant change in active properties of SON neurons was shown after bath application of BS venom; including a decrease in the number of evoked action potential along with an increase in half width and decay time of action potential and a significant decrease in after-hyperpolarization amplitude. Finally, a decreased latency to the first spike accompanied by a lower current threshold to elicit the first spike was shown compared with the values before venom application. These effects are possibly through blocking different ion channels including potassium channels. Further experiments using different fractions of the venom is required to specify venom effects on various ion channels.
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Affiliation(s)
- Akram Aboutorabi
- Student Research Committee, School of Pharmacy, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
| | - Nima Naderi
- Department of Toxicology and Pharmacology, School of Pharmacy, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
| | | | - Hossein Zolfagharian
- Department of venomous animals and antivenom production Razi vaccine and serum research institute Agricultural research education and extension organization ( AREEO), Karaj, Iran.
| | - Hossein Vatanpour
- Department of Toxicology and Pharmacology, School of Pharmacy, Shahid Beheshti University of Medical Sciences, Tehran, Iran.,Corresponding author: E-mail:
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