51
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Zhang J, Chen X, Eaton M, Wu J, Ma Z, Lai S, Park A, Ahmad TS, Que Z, Lee JH, Xiao T, Li Y, Wang Y, Olivero-Acosta MI, Schaber JA, Jayant K, Yuan C, Huang Z, Lanman NA, Skarnes WC, Yang Y. Severe deficiency of the voltage-gated sodium channel Na V1.2 elevates neuronal excitability in adult mice. Cell Rep 2021; 36:109495. [PMID: 34348148 PMCID: PMC8382316 DOI: 10.1016/j.celrep.2021.109495] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Revised: 06/30/2021] [Accepted: 07/14/2021] [Indexed: 12/13/2022] Open
Abstract
Scn2a encodes the voltage-gated sodium channel NaV1.2, a main mediator of neuronal action potential firing. The current paradigm suggests that NaV1.2 gain-of-function variants enhance neuronal excitability, resulting in epilepsy, whereas NaV1.2 deficiency impairs neuronal excitability, contributing to autism. However, this paradigm does not explain why ∼20%-30% of individuals with NaV1.2 deficiency still develop seizures. Here, we report the counterintuitive finding that severe NaV1.2 deficiency results in increased neuronal excitability. Using a NaV1.2-deficient mouse model, we show enhanced intrinsic excitability of principal neurons in the prefrontal cortex and striatum, brain regions known to be involved in Scn2a-related seizures. This increased excitability is autonomous and reversible by genetic restoration of Scn2a expression in adult mice. RNA sequencing reveals downregulation of multiple potassium channels, including KV1.1. Correspondingly, KV channel openers alleviate the hyperexcitability of NaV1.2-deficient neurons. This unexpected neuronal hyperexcitability may serve as a cellular basis underlying NaV1.2 deficiency-related seizures.
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Affiliation(s)
- Jingliang Zhang
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, IN 47907, USA; Purdue Institute for Integrative Neuroscience, Purdue University, West Lafayette, IN 47907, USA
| | - Xiaoling Chen
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, IN 47907, USA; Purdue Institute for Integrative Neuroscience, Purdue University, West Lafayette, IN 47907, USA; Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN 47907, USA
| | - Muriel Eaton
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, IN 47907, USA; Purdue Institute for Integrative Neuroscience, Purdue University, West Lafayette, IN 47907, USA
| | - Jiaxiang Wu
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, IN 47907, USA; Purdue Institute for Integrative Neuroscience, Purdue University, West Lafayette, IN 47907, USA
| | - Zhixiong Ma
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, IN 47907, USA; Purdue Institute for Integrative Neuroscience, Purdue University, West Lafayette, IN 47907, USA
| | - Shirong Lai
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, IN 47907, USA; Purdue Institute for Integrative Neuroscience, Purdue University, West Lafayette, IN 47907, USA
| | - Anthony Park
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, IN 47907, USA; Purdue Institute for Integrative Neuroscience, Purdue University, West Lafayette, IN 47907, USA
| | - Talha S Ahmad
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, IN 47907, USA; Purdue Institute for Integrative Neuroscience, Purdue University, West Lafayette, IN 47907, USA
| | - Zhefu Que
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, IN 47907, USA; Purdue Institute for Integrative Neuroscience, Purdue University, West Lafayette, IN 47907, USA
| | - Ji Hea Lee
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, IN 47907, USA; Purdue Institute for Integrative Neuroscience, Purdue University, West Lafayette, IN 47907, USA
| | - Tiange Xiao
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, IN 47907, USA; Purdue Institute for Integrative Neuroscience, Purdue University, West Lafayette, IN 47907, USA
| | - Yuansong Li
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, IN 47907, USA; Purdue Institute for Integrative Neuroscience, Purdue University, West Lafayette, IN 47907, USA
| | - Yujia Wang
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, IN 47907, USA; Purdue Institute for Integrative Neuroscience, Purdue University, West Lafayette, IN 47907, USA
| | - Maria I Olivero-Acosta
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, IN 47907, USA; Purdue Institute for Integrative Neuroscience, Purdue University, West Lafayette, IN 47907, USA
| | - James A Schaber
- Bioscience Imaging Facility, Bindley Bioscience Center, Purdue University, West Lafayette, IN 47907, USA
| | - Krishna Jayant
- Purdue Institute for Integrative Neuroscience, Purdue University, West Lafayette, IN 47907, USA; Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN 47907, USA
| | - Chongli Yuan
- Davidson School of Chemical Engineering, Purdue University, West Lafayette, IN 47907, USA
| | - Zhuo Huang
- Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Sciences, Peking University Health Science Center, Beijing 100191, China
| | - Nadia A Lanman
- Department of Comparative Pathobiology, Purdue University, West Lafayette, IN 47907, USA; Purdue Center for Cancer Research, Purdue University, West Lafayette, IN 47907, USA
| | - William C Skarnes
- The Jackson Laboratory for Genomic Medicine, Farmington, CT 06032, USA
| | - Yang Yang
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, IN 47907, USA; Purdue Institute for Integrative Neuroscience, Purdue University, West Lafayette, IN 47907, USA.
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52
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Zhang Y, Tachtsidis G, Schob C, Koko M, Hedrich UBS, Lerche H, Lemke JR, Haeringen A, Ruivenkamp C, Prescott T, Tveten K, Gerstner T, Pruniski B, DiTroia S, VanNoy GE, Rehm HL, McLaughlin H, Bolz HJ, Zechner U, Bryant E, McDonough T, Kindler S, Bähring R. KCND2 variants associated with global developmental delay differentially impair Kv4.2 channel gating. Hum Mol Genet 2021; 30:2300-2314. [PMID: 34245260 DOI: 10.1093/hmg/ddab192] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 07/06/2021] [Accepted: 07/07/2021] [Indexed: 11/13/2022] Open
Abstract
Here, we report on six unrelated individuals, all presenting with early-onset global developmental delay, associated with impaired motor, speech and cognitive development, partly with developmental epileptic encephalopathy and physical dysmorphisms. All individuals carry heterozygous missense variants of KCND2, which encodes the voltage-gated potassium (Kv) channel α-subunit Kv4.2. The amino acid substitutions associated with the variants, p.(Glu323Lys) (E323K), p.(Pro403Ala) (P403A), p.(Val404Leu) (V404L) and p.(Val404Met) (V404M), affect sites known to be critical for channel gating. To unravel their likely pathogenicity, recombinant mutant channels were studied in the absence and presence of auxiliary β-subunits under two-electrode voltage-clamp in Xenopus oocytes. All channel mutants exhibited slowed and incomplete macroscopic inactivation, and the P403A variant in addition slowed activation. Co-expression of KChIP2 or DPP6 augmented the functional expression of both wild-type and mutant channels, however, the auxiliary β-subunit-mediated gating modifications differed from wild-type and among mutants. To simulate the putative setting in the affected individuals, heteromeric Kv4.2 channels (wild-type + mutant) were studied as ternary complexes (containing both KChIP2 and DPP6). In the heteromeric ternary configuration, the E323K variant exhibited only marginal functional alterations compared to homomeric wild-type ternary, compatible with mild loss-of-function. By contrast, the P403A, V404L and V404M variants displayed strong gating impairment in the heteromeric ternary configuration, compatible with loss or gain-of-function. Our results support the etiological involvement of Kv4.2 channel gating impairment in early-onset monogenic global developmental delay. In addition, they suggest that gain-of-function mechanisms associated with a substitution of V404 increase epileptic seizure susceptibility.
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Affiliation(s)
- Yongqiang Zhang
- Institute for Cellular and Integrative Physiology, Center for Experimental Medicine, University Hospital Hamburg-Eppendorf, Hamburg, Germany.,Southeast University, Nanjing, China
| | - Georgios Tachtsidis
- Institute for Cellular and Integrative Physiology, Center for Experimental Medicine, University Hospital Hamburg-Eppendorf, Hamburg, Germany
| | - Claudia Schob
- Institute for Human Genetics, University Hospital Hamburg-Eppendorf, Hamburg, Germany
| | - Mahmoud Koko
- Department of Neurology and Epileptology, Hertie-Institute for Clinical Brain Research, Tübingen, Germany
| | - Ulrike B S Hedrich
- Department of Neurology and Epileptology, Hertie-Institute for Clinical Brain Research, Tübingen, Germany
| | - Holger Lerche
- Department of Neurology and Epileptology, Hertie-Institute for Clinical Brain Research, Tübingen, Germany
| | - Johannes R Lemke
- University Center for Rare Diseases, Institute for Human Genetics, University Hospital, Leipzig, Germany
| | - Arie Haeringen
- Department of Clinical Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Claudia Ruivenkamp
- Department of Clinical Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Trine Prescott
- Department of Medical Genetics, Telemark Hospital Trust, Skien, Norway
| | - Kristian Tveten
- Department of Medical Genetics, Telemark Hospital Trust, Skien, Norway
| | - Thorsten Gerstner
- Department of Child Neurology and Rehabilitation and Department of Pediatrics, Hospital of Southern Norway, Arendal, Norway
| | - Brianna Pruniski
- Division of Genetics & Metabolism, Phoenix Children's Medical Group, Phoenix, AZ, USA
| | - Stephanie DiTroia
- Center for Mendelian Genomics and Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Grace E VanNoy
- Center for Mendelian Genomics and Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Heidi L Rehm
- Center for Mendelian Genomics and Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | | | - Hanno J Bolz
- Senckenberg Centre for Human Genetics, Frankfurt/Main, Germany.,Institute of Human Genetics, University Hospital of Cologne, Cologne, Germany
| | - Ulrich Zechner
- Senckenberg Centre for Human Genetics, Frankfurt/Main, Germany.,Institute of Human Genetics, University Medical Center Mainz, Mainz, Germany
| | - Emily Bryant
- Ann & Robert H Lurie Children's Hospital of Chicago, Department of Pediatrics, Northwestern University Feinberg Scool of Medicine, Chicago, IL, USA
| | - Tiffani McDonough
- Ann & Robert H Lurie Children's Hospital of Chicago, Department of Pediatrics, Northwestern University Feinberg Scool of Medicine, Chicago, IL, USA
| | - Stefan Kindler
- Institute for Human Genetics, University Hospital Hamburg-Eppendorf, Hamburg, Germany
| | - Robert Bähring
- Institute for Cellular and Integrative Physiology, Center for Experimental Medicine, University Hospital Hamburg-Eppendorf, Hamburg, Germany
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53
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Mathie A, Veale EL, Golluscio A, Holden RG, Walsh Y. Pharmacological Approaches to Studying Potassium Channels. Handb Exp Pharmacol 2021; 267:83-111. [PMID: 34195873 DOI: 10.1007/164_2021_502] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In this review, we consider the pharmacology of potassium channels from the perspective of these channels as therapeutic targets. Firstly, we describe the three main families of potassium channels in humans and disease states where they are implicated. Secondly, we describe the existing therapeutic agents which act on potassium channels and outline why these channels represent an under-exploited therapeutic target with potential for future drug development. Thirdly, we consider the evidence desired in order to embark on a drug discovery programme targeting a particular potassium channel. We have chosen two "case studies": activators of the two-pore domain potassium (K2P) channel TREK-2 (K2P10.1), for the treatment of pain and inhibitors of the voltage-gated potassium channel KV1.3, for use in autoimmune diseases such as multiple sclerosis. We describe the evidence base to suggest why these are viable therapeutic targets. Finally, we detail the main technical approaches available to characterise the pharmacology of potassium channels and identify novel regulatory compounds. We draw particular attention to the Comprehensive in vitro Proarrhythmia Assay initiative (CiPA, https://cipaproject.org ) project for cardiac safety, as an example of what might be both desirable and possible in the future, for ion channel regulator discovery projects.
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Affiliation(s)
- Alistair Mathie
- Medway School of Pharmacy, University of Kent, Kent, UK. .,Medway School of Pharmacy, University of Greenwich, London, UK. .,School of Engineering, Arts, Science and Technology, University of Suffolk, Ipswich, UK.
| | - Emma L Veale
- Medway School of Pharmacy, University of Kent, Kent, UK.,Medway School of Pharmacy, University of Greenwich, London, UK
| | - Alessia Golluscio
- Medway School of Pharmacy, University of Kent, Kent, UK.,Medway School of Pharmacy, University of Greenwich, London, UK
| | - Robyn G Holden
- Medway School of Pharmacy, University of Kent, Kent, UK.,Medway School of Pharmacy, University of Greenwich, London, UK
| | - Yvonne Walsh
- Medway School of Pharmacy, University of Kent, Kent, UK.,Medway School of Pharmacy, University of Greenwich, London, UK
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54
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Miljanovic N, Hauck SM, van Dijk RM, Di Liberto V, Rezaei A, Potschka H. Proteomic signature of the Dravet syndrome in the genetic Scn1a-A1783V mouse model. Neurobiol Dis 2021; 157:105423. [PMID: 34144125 DOI: 10.1016/j.nbd.2021.105423] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2021] [Revised: 05/14/2021] [Accepted: 06/08/2021] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Dravet syndrome is a rare, severe pediatric epileptic encephalopathy associated with intellectual and motor disabilities. Proteomic profiling in a mouse model of Dravet syndrome can provide information about the molecular consequences of the genetic deficiency and about pathophysiological mechanisms developing during the disease course. METHODS A knock-in mouse model of Dravet syndrome with Scn1a haploinsufficiency was used for whole proteome, seizure, and behavioral analysis. Hippocampal tissue was dissected from two- (prior to epilepsy manifestation) and four- (following epilepsy manifestation) week-old male mice and analyzed using LC-MS/MS with label-free quantification. Proteomic data sets were subjected to bioinformatic analysis including pathway enrichment analysis. The differential expression of selected proteins was confirmed by immunohistochemical staining. RESULTS The findings confirmed an increased susceptibility to hyperthermia-associated seizures, the development of spontaneous seizures, and behavioral alterations in the novel Scn1a-A1873V mouse model of Dravet syndrome. As expected, proteomic analysis demonstrated more pronounced alterations following epilepsy manifestation. In particular, proteins involved in neurotransmitter dynamics, receptor and ion channel function, synaptic plasticity, astrogliosis, neoangiogenesis, and nitric oxide signaling showed a pronounced regulation in Dravet mice. Pathway enrichment analysis identified several significantly regulated pathways at the later time point, with pathways linked to synaptic transmission and glutamatergic signaling dominating the list. CONCLUSION In conclusion, the whole proteome analysis in a mouse model of Dravet syndrome demonstrated complex molecular alterations in the hippocampus. Some of these alterations may have an impact on excitability or may serve a compensatory function, which, however, needs to be further confirmed by future investigations. The proteomic data indicate that, due to the molecular consequences of the genetic deficiency, the pathophysiological mechanisms may become more complex during the course of the disease. As a result, the management of Dravet syndrome may need to consider further molecular and cellular alterations. Ensuing functional follow-up studies, this data set may provide valuable guidance for the future development of novel therapeutic approaches.
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Affiliation(s)
- Nina Miljanovic
- Institute of Pharmacology, Toxicology & Pharmacy, Ludwig-Maximilians-University (LMU), Munich, Germany; Graduate School of Systemic Neurosciences (GSN), Ludwig-Maximilians-University (LMU), Munich, Germany
| | - Stefanie M Hauck
- Research Unit Protein Science, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Germany
| | - R Maarten van Dijk
- Institute of Pharmacology, Toxicology & Pharmacy, Ludwig-Maximilians-University (LMU), Munich, Germany
| | - Valentina Di Liberto
- Institute of Pharmacology, Toxicology & Pharmacy, Ludwig-Maximilians-University (LMU), Munich, Germany
| | - Ali Rezaei
- Institute of Pharmacology, Toxicology & Pharmacy, Ludwig-Maximilians-University (LMU), Munich, Germany; Graduate School of Systemic Neurosciences (GSN), Ludwig-Maximilians-University (LMU), Munich, Germany
| | - Heidrun Potschka
- Institute of Pharmacology, Toxicology & Pharmacy, Ludwig-Maximilians-University (LMU), Munich, Germany.
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55
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Springer K, Varghese N, Tzingounis AV. Flexible Stoichiometry: Implications for KCNQ2- and KCNQ3-Associated Neurodevelopmental Disorders. Dev Neurosci 2021; 43:191-200. [PMID: 33794528 PMCID: PMC8440324 DOI: 10.1159/000515495] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Accepted: 02/25/2021] [Indexed: 11/19/2022] Open
Abstract
KCNQ2 and KCNQ3 pathogenic channel variants have been associated with a spectrum of developmentally regulated diseases that vary in age of onset, severity, and whether it is transient (i.e., benign familial neonatal seizures) or long-lasting (i.e., developmental and epileptic encephalopathy). KCNQ2 and KCNQ3 channels have also emerged as a target for novel antiepileptic drugs as their activation could reduce epileptic activity. Consequently, a great effort has taken place over the last 2 decades to understand the mechanisms that control the assembly, gating, and modulation of KCNQ2 and KCNQ3 channels. The current view that KCNQ2 and KCNQ3 channels assemble as heteromeric channels (KCNQ2/3) forms the basis of our understanding of KCNQ2 and KCNQ3 channelopathies and drug design. Here, we review the evidence that supports the formation of KCNQ2/3 heteromers in neurons. We also highlight functional and transcriptomic studies that suggest channel composition might not be necessarily fixed in the nervous system, but rather is dynamic and flexible, allowing some neurons to express KCNQ2 and KCNQ3 homomers. We propose that to fully understand KCNQ2 and KCNQ3 channelopathies, we need to adopt a more flexible view of KCNQ2 and KCNQ3 channel stoichiometry, which might differ across development, brain regions, cell types, and disease states.
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Affiliation(s)
- Kristen Springer
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut, USA
| | - Nissi Varghese
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut, USA
| | - Anastasios V Tzingounis
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut, USA
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56
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Qaswal AB, Ababneh O, Khreesha L, Al-Ani A, Suleihat A, Abbad M. Mathematical Modeling of Ion Quantum Tunneling Reveals Novel Properties of Voltage-Gated Channels and Quantum Aspects of Their Pathophysiology in Excitability-Related Disorders. PATHOPHYSIOLOGY 2021; 28:116-154. [PMID: 35366274 PMCID: PMC8830480 DOI: 10.3390/pathophysiology28010010] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Revised: 03/03/2021] [Accepted: 03/04/2021] [Indexed: 02/08/2023] Open
Abstract
Voltage-gated channels are crucial in action potential initiation and propagation and there are many diseases and disorders related to them. Additionally, the classical mechanics are the main mechanics used to describe the function of the voltage-gated channels and their related abnormalities. However, the quantum mechanics should be considered to unravel new aspects in the voltage-gated channels and resolve the problems and challenges that classical mechanics cannot solve. In the present study, the aim is to mathematically show that quantum mechanics can exhibit a powerful tendency to unveil novel electrical features in voltage-gated channels and be used as a promising tool to solve the problems and challenges in the pathophysiology of excitability-related diseases. The model of quantum tunneling of ions through the intracellular hydrophobic gate is used to evaluate the influence of membrane potential and gating free energy on the tunneling probability, single channel conductance, and quantum membrane conductance. This evaluation is mainly based on graphing the mathematical relationships between these variables. The obtained mathematical graphs showed that ions can achieve significant quantum membrane conductance, which can affect the resting membrane potential and the excitability of cells. In the present work, quantum mechanics reveals original electrical properties associated with voltage-gated channels and introduces new insights and implications into the pathophysiology of excitability- related disorders. In addition, the present work sets a mathematical and theoretical framework that can be utilized to conduct experimental studies in order to explore the quantum aspects of voltage-gated channels and the quantum bioelectrical property of biological membranes.
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Affiliation(s)
- Abdallah Barjas Qaswal
- Department of Internship Program, Jordan University Hospital, The University of Jordan, Amman 11942, Jordan
- Correspondence:
| | - Omar Ababneh
- Department of Anesthesia and Intensive Care, School of Medicine, The University of Jordan, Amman 11942, Jordan;
| | - Lubna Khreesha
- Department of Special Surgery, School of Medicine, The University of Jordan, Amman 11942, Jordan;
| | - Abdallah Al-Ani
- School of Medicine, The University of Jordan, Amman 11942, Jordan;
| | - Ahmad Suleihat
- Department of General Surgery, School of Medicine, The University of Jordan, Amman 11942, Jordan; (A.S.); (M.A.)
| | - Mutaz Abbad
- Department of General Surgery, School of Medicine, The University of Jordan, Amman 11942, Jordan; (A.S.); (M.A.)
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57
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Kuchenbuch M, Nabbout R, Yochum M, Sauleau P, Modolo J, Wendling F, Benquet P. In silico model reveals the key role of GABA in KCNT1-epilepsy in infancy with migrating focal seizures. Epilepsia 2021; 62:683-697. [PMID: 33617692 DOI: 10.1111/epi.16834] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Revised: 12/08/2020] [Accepted: 01/18/2021] [Indexed: 02/06/2023]
Abstract
OBJECTIVE This study was undertaken to investigate how gain of function (GOF) of slack channel due to a KCNT1 pathogenic variant induces abnormal neuronal cortical network activity and generates specific electroencephalographic (EEG) patterns of epilepsy in infancy with migrating focal seizures. METHODS We used detailed microscopic computational models of neurons to explore the impact of GOF of slack channel (explicitly coded) on each subtype of neurons and on a cortical micronetwork. Then, we adapted a thalamocortical macroscopic model considering results obtained in detailed models and immature properties related to epileptic brain in infancy. Finally, we compared simulated EEGs resulting from the macroscopic model with interictal and ictal patterns of affected individuals using our previously reported EEG markers. RESULTS The pathogenic variants of KCNT1 strongly decreased the firing rate properties of γ-aminobutyric acidergic (GABAergic) interneurons and, to a lesser extent, those of pyramidal cells. This change led to hyperexcitability with increased synchronization in a cortical micronetwork. At the macroscopic scale, introducing slack GOF effect resulted in epilepsy of infancy with migrating focal seizures (EIMFS) EEG interictal patterns. Increased excitation-to-inhibition ratio triggered seizure, but we had to add dynamic depolarizing GABA between somatostatin-positive interneurons and pyramidal cells to obtain migrating seizure. The simulated migrating seizures were close to EIMFS seizures, with similar values regarding the delay between the different ictal activities (one of the specific EEG markers of migrating focal seizures due to KCNT1 pathogenic variants). SIGNIFICANCE This study illustrates the interest of biomathematical models to explore pathophysiological mechanisms bridging the gap between the functional effect of gene pathogenic variants and specific EEG phenotype. Such models can be complementary to in vitro cellular and animal models. This multiscale approach provides an in silico framework that can be further used to identify candidate innovative therapies.
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Affiliation(s)
- Mathieu Kuchenbuch
- LTSI-U1099, Université de Rennes 1, INSERM, Rennes, France.,Department of Pediatric Neurology, Reference Center for Rare Epilepsies, Hôpital Necker-Enfants malades, member of European Network EPICARE, Paris, France.,Laboratory of Translational Research for Neurological Disorders (UMR 1163), IHU Imagine Institute of Genetic Diseases, INSERM, University of Paris, Paris, France
| | - Rima Nabbout
- Department of Pediatric Neurology, Reference Center for Rare Epilepsies, Hôpital Necker-Enfants malades, member of European Network EPICARE, Paris, France.,Laboratory of Translational Research for Neurological Disorders (UMR 1163), IHU Imagine Institute of Genetic Diseases, INSERM, University of Paris, Paris, France
| | - Maxime Yochum
- LTSI-U1099, Université de Rennes 1, INSERM, Rennes, France
| | - Paul Sauleau
- CHU de Rennes (Department of Neurophysiology), "Behavior and Basal Ganglia" Research Unit (EA4712), University of Rennes, Rennes, France
| | - Julien Modolo
- LTSI-U1099, Université de Rennes 1, INSERM, Rennes, France
| | | | - Pascal Benquet
- LTSI-U1099, Université de Rennes 1, INSERM, Rennes, France
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58
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Gripp KW, Smithson SF, Scurr IJ, Baptista J, Majumdar A, Pierre G, Williams M, Henderson LB, Wentzensen IM, McLaughlin H, Leeuwen L, Simon MEH, van Binsbergen E, Dinulos MBP, Kaplan JD, McRae A, Superti-Furga A, Good JM, Kutsche K. Syndromic disorders caused by gain-of-function variants in KCNH1, KCNK4, and KCNN3-a subgroup of K + channelopathies. Eur J Hum Genet 2021; 29:1384-1395. [PMID: 33594261 PMCID: PMC8440610 DOI: 10.1038/s41431-021-00818-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Revised: 01/18/2021] [Accepted: 01/22/2021] [Indexed: 12/13/2022] Open
Abstract
Decreased or increased activity of potassium channels caused by loss-of-function and gain-of-function (GOF) variants in the corresponding genes, respectively, underlies a broad spectrum of human disorders affecting the central nervous system, heart, kidney, and other organs. While the association of epilepsy and intellectual disability (ID) with variants affecting function in genes encoding potassium channels is well known, GOF missense variants in K+ channel encoding genes in individuals with syndromic developmental disorders have only recently been recognized. These syndromic phenotypes include Zimmermann–Laband and Temple–Baraitser syndromes, caused by dominant variants in KCNH1, FHEIG syndrome due to dominant variants in KCNK4, and the clinical picture associated with dominant variants in KCNN3. Here we review the presentation of these individuals, including five newly reported with variants in KCNH1 and three additional individuals with KCNN3 variants, all variants likely affecting function. There is notable overlap in the phenotypic findings of these syndromes associated with dominant KCNN3, KCNH1, and KCNK4 variants, sharing developmental delay and/or ID, coarse facial features, gingival enlargement, distal digital hypoplasia, and hypertrichosis. We suggest to combine the phenotypes and define a new subgroup of potassium channelopathies caused by increased K+ conductance, referred to as syndromic neurodevelopmental K+ channelopathies due to dominant variants in KCNH1, KCNK4, or KCNN3.
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Affiliation(s)
- Karen W Gripp
- Division of Medical Genetics, Alfred I. duPont Hospital for Children, Wilmington, DE, USA
| | - Sarah F Smithson
- Department of Clinical Genetics, University Hospitals Bristol and Weston, Bristol, UK
| | - Ingrid J Scurr
- Department of Clinical Genetics, University Hospitals Bristol and Weston, Bristol, UK
| | - Julia Baptista
- Exeter Genomics Laboratory, Royal Devon & Exeter NHS Foundation Trust, Exeter, UK.,College of Medicine and Health, University of Exeter, Exeter, UK
| | - Anirban Majumdar
- Department of Paediatric Neurology, Bristol Royal Hospital for Children, Bristol, UK
| | - Germaine Pierre
- Department of Paediatric Metabolic Medicine, Bristol Royal Hospital for Children, Bristol, UK
| | - Maggie Williams
- Bristol Genetics Laboratory, North Bristol NHS Trust, Bristol, UK
| | | | | | | | - Lisette Leeuwen
- Department of Genetics, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Marleen E H Simon
- Department of Genetics, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Ellen van Binsbergen
- Department of Genetics, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Mary Beth P Dinulos
- Section of Genetics and Child Development, Children's Hospital at Dartmouth, Lebanon, NH, USA
| | - Julie D Kaplan
- Division of Medical Genetics, Alfred I. duPont Hospital for Children, Wilmington, DE, USA
| | - Anne McRae
- Division of Genetics, Birth Defects and Metabolism, Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, IL, USA
| | - Andrea Superti-Furga
- Division of Genetic Medicine, Lausanne University Hospital, Lausanne, Switzerland
| | - Jean-Marc Good
- Division of Genetic Medicine, Lausanne University Hospital, Lausanne, Switzerland
| | - Kerstin Kutsche
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
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59
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Simkin D, Marshall KA, Vanoye CG, Desai RR, Bustos BI, Piyevsky BN, Ortega JA, Forrest M, Robertson GL, Penzes P, Laux LC, Lubbe SJ, Millichap JJ, George AL, Kiskinis E. Dyshomeostatic modulation of Ca 2+-activated K + channels in a human neuronal model of KCNQ2 encephalopathy. eLife 2021; 10:64434. [PMID: 33544076 PMCID: PMC7864629 DOI: 10.7554/elife.64434] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Accepted: 01/20/2021] [Indexed: 12/22/2022] Open
Abstract
Mutations in KCNQ2, which encodes a pore-forming K+ channel subunit responsible for neuronal M-current, cause neonatal epileptic encephalopathy, a complex disorder presenting with severe early-onset seizures and impaired neurodevelopment. The condition is exceptionally difficult to treat, partially because the effects of KCNQ2 mutations on the development and function of human neurons are unknown. Here, we used induced pluripotent stem cells (iPSCs) and gene editing to establish a disease model and measured the functional properties of differentiated excitatory neurons. We find that patient iPSC-derived neurons exhibit faster action potential repolarization, larger post-burst afterhyperpolarization and a functional enhancement of Ca2+-activated K+ channels. These properties, which can be recapitulated by chronic inhibition of M-current in control neurons, facilitate a burst-suppression firing pattern that is reminiscent of the interictal electroencephalography pattern in patients. Our findings suggest that dyshomeostatic mechanisms compound KCNQ2 loss-of-function leading to alterations in the neurodevelopmental trajectory of patient iPSC-derived neurons.
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Affiliation(s)
- Dina Simkin
- The Ken & Ruth Davee Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, United States.,Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, United States
| | - Kelly A Marshall
- The Ken & Ruth Davee Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, United States
| | - Carlos G Vanoye
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, United States
| | - Reshma R Desai
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, United States
| | - Bernabe I Bustos
- The Ken & Ruth Davee Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, United States
| | - Brandon N Piyevsky
- The Ken & Ruth Davee Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, United States
| | - Juan A Ortega
- The Ken & Ruth Davee Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, United States
| | - Marc Forrest
- Department of Physiology, Feinberg School of Medicine, Northwestern University, Chicago, United States.,Center for Autism and Neurodevelopment, Feinberg School of Medicine, Northwestern University, Chicago, United States
| | - Gabriella L Robertson
- The Ken & Ruth Davee Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, United States
| | - Peter Penzes
- Department of Physiology, Feinberg School of Medicine, Northwestern University, Chicago, United States.,Center for Autism and Neurodevelopment, Feinberg School of Medicine, Northwestern University, Chicago, United States
| | - Linda C Laux
- Epilepsy Center and Division of Neurology, Departments of Pediatrics and Neurology, Ann & Robert H. Lurie Children's Hospital of Chicago, Feinberg School of Medicine, Northwestern University, Chicago, United States
| | - Steven J Lubbe
- The Ken & Ruth Davee Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, United States
| | - John J Millichap
- Epilepsy Center and Division of Neurology, Departments of Pediatrics and Neurology, Ann & Robert H. Lurie Children's Hospital of Chicago, Feinberg School of Medicine, Northwestern University, Chicago, United States
| | - Alfred L George
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, United States
| | - Evangelos Kiskinis
- The Ken & Ruth Davee Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, United States.,Department of Physiology, Feinberg School of Medicine, Northwestern University, Chicago, United States
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60
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Disruption of NEUROD2 causes a neurodevelopmental syndrome with autistic features via cell-autonomous defects in forebrain glutamatergic neurons. Mol Psychiatry 2021; 26:6125-6148. [PMID: 34188164 PMCID: PMC8760061 DOI: 10.1038/s41380-021-01179-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Revised: 05/17/2021] [Accepted: 05/26/2021] [Indexed: 02/06/2023]
Abstract
While the transcription factor NEUROD2 has recently been associated with epilepsy, its precise role during nervous system development remains unclear. Using a multi-scale approach, we set out to understand how Neurod2 deletion affects the development of the cerebral cortex in mice. In Neurod2 KO embryos, cortical projection neurons over-migrated, thereby altering the final size and position of layers. In juvenile and adults, spine density and turnover were dysregulated in apical but not basal compartments in layer 5 neurons. Patch-clamp recordings in layer 5 neurons of juvenile mice revealed increased intrinsic excitability. Bulk RNA sequencing showed dysregulated expression of many genes associated with neuronal excitability and synaptic function, whose human orthologs were strongly associated with autism spectrum disorders (ASD). At the behavior level, Neurod2 KO mice displayed social interaction deficits, stereotypies, hyperactivity, and occasionally spontaneous seizures. Mice heterozygous for Neurod2 had similar defects, indicating that Neurod2 is haploinsufficient. Finally, specific deletion of Neurod2 in forebrain excitatory neurons recapitulated cellular and behavioral phenotypes found in constitutive KO mice, revealing the region-specific contribution of dysfunctional Neurod2 in symptoms. Informed by these neurobehavioral features in mouse mutants, we identified eleven patients from eight families with a neurodevelopmental disorder including intellectual disability and ASD associated with NEUROD2 pathogenic mutations. Our findings demonstrate crucial roles for Neurod2 in neocortical development, whose alterations can cause neurodevelopmental disorders including intellectual disability and ASD.
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61
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Jedrychowska J, Gasanov EV, Korzh V. Kcnb1 plays a role in development of the inner ear. Dev Biol 2020; 471:65-75. [PMID: 33316259 DOI: 10.1016/j.ydbio.2020.12.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2020] [Revised: 12/03/2020] [Accepted: 12/07/2020] [Indexed: 10/22/2022]
Abstract
The function of the inner ear depends on the maintenance of high concentrations of K+ ions. The slow-inactivating delayed rectifier Kv2.1/KCNB1 channel works in the inner ear in mammals. The kcnb1 gene is expressed in the otic vesicle of developing zebrafish, suggesting its role in development of the inner ear. In the present study, we found that a Kcnb1 loss-of-function mutation affected development of the inner ear at multiple levels, including otic vesicle expansion, otolith formation, and the proliferation and differentiation of mechanosensory cells. This resulted in defects of kinocilia and stereocilia and abnormal function of the inner ear detected by behavioral assays. The quantitative transcriptional analysis of 75 genes demonstrated that the kcnb1 mutation affected the transcription of genes that are involved in K+ metabolism, cell proliferation, cilia development, and intracellular protein trafficking. These results demonstrate a role for Kv2.1/Kcnb1 channels in development of the inner ear in zebrafish.
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Affiliation(s)
- Justyna Jedrychowska
- International Institute of Molecular and Cell Biology in Warsaw, Poland; Postgraduate School of Molecular Medicine, Warsaw Medical University, Warsaw, Poland
| | - Eugene V Gasanov
- 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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62
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Hung TY, Huang CW, Wu SN. High ability of zileuton ((±)-1-(1-benzo[b]thien-2-ylethyl)-1-hydroxyurea) to stimulate I K(Ca) but suppress I K(DR) and I K(M) independently of 5-lipoxygenase inhibition. Eur J Pharmacol 2020; 887:173482. [PMID: 32795513 DOI: 10.1016/j.ejphar.2020.173482] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Revised: 08/07/2020] [Accepted: 08/08/2020] [Indexed: 12/16/2022]
Abstract
Zileuton (Zyflo®) is regarded to be an inhibitor of 5-lipoxygenase. Although its effect on Ca2+-activated K+ currents has been reported, its overall ionic effects on neurons are uncertain. In whole-cell current recordings, zileuton increased the amplitude of Ca2+-activated K+ currents with an EC50 of 3.2 μM in pituitary GH3 lactotrophs. Furthermore, zileuton decreased the amplitudes of both delayed-rectifier K+ current (IK(DR)) and M-type K+ current (IK(M)). Conversely, no modification of hyperpolarization-activated cation current (Ih) was demonstrated in its presence of zileuton, although the subsequent addition of cilobradine effectively suppressed the current. In inside-out current recordings, the addition of zileuton to the bath increased the probability of large-conductance Ca2+-activated K+ (BKCa) channels; however, the subsequent addition of GAL-021 effectively reversed the stimulation of channel activity. The kinetic analyses showed an evident shortening in the slow component of mean closed time of BKCa channels in the presence of zileuton, with minimal change in mean open time or that in the fast component of mean closed time. The elevation of BKCa channels caused by zileuton was also observed in hippocampal mHippoE-14 neurons, without any modification of single-channel amplitude. In conclusion, except for its suppression of 5-lipoxygenase, our results indicate that zileuton does not exclusively act on BKCa channels, and its inhibitory effects on IK(DR) and IK(M) may combine to exert strong influence on the functional activities of electrically excitable cells in vivo.
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Affiliation(s)
- Te-Yu Hung
- Department of Pediatrics, Chi-Mei Medical Center, Tainan, Taiwan
| | - Chin-Wei Huang
- Department of Neurology, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
| | - Sheng-Nan Wu
- Department of Physiology, National Cheng Kung University Medical College, Tainan, Taiwan; Institute of Basic Medical Sciences, National Cheng Kung University Medical College, Tainan, Taiwan; Department of Medical Research, China Medical University Hospital, China Medical University, Taichung City, Taiwan.
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63
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Pantazis A, Kaneko M, Angelini M, Steccanella F, Westerlund AM, Lindström SH, Nilsson M, Delemotte L, Saitta SC, Olcese R. Tracking the motion of the K V1.2 voltage sensor reveals the molecular perturbations caused by a de novo mutation in a case of epilepsy. J Physiol 2020; 598:5245-5269. [PMID: 32833227 PMCID: PMC8923147 DOI: 10.1113/jp280438] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Accepted: 08/14/2020] [Indexed: 12/28/2022] Open
Abstract
KEY POINTS KV1.2 channels, encoded by the KCNA2 gene, regulate neuronal excitability by conducting K+ upon depolarization. A new KCNA2 missense variant was discovered in a patient with epilepsy, causing amino acid substitution F302L at helix S4, in the KV1.2 voltage-sensing domain. Immunocytochemistry and flow cytometry showed that F302L does not impair KCNA2 subunit surface trafficking. Molecular dynamics simulations indicated that F302L alters the exposure of S4 residues to membrane lipids. Voltage clamp fluorometry revealed that the voltage-sensing domain of KV1.2-F302L channels is more sensitive to depolarization. Accordingly, KV1.2-F302L channels opened faster and at more negative potentials; however, they also exhibited enhanced inactivation: that is, F302L causes both gain- and loss-of-function effects. Coexpression of KCNA2-WT and -F302L did not fully rescue these effects. The proband's symptoms are more characteristic of patients with loss of KCNA2 function. Enhanced KV1.2 inactivation could lead to increased synaptic release in excitatory neurons, steering neuronal circuits towards epilepsy. ABSTRACT An exome-based diagnostic panel in an infant with epilepsy revealed a previously unreported de novo missense variant in KCNA2, which encodes voltage-gated K+ channel KV1.2. This variant causes substitution F302L, in helix S4 of the KV1.2 voltage-sensing domain (VSD). F302L does not affect KCNA2 subunit membrane trafficking. However, it does alter channel functional properties, accelerating channel opening at more hyperpolarized membrane potentials, indicating gain of function. F302L also caused loss of KV1.2 function via accelerated inactivation onset, decelerated recovery and shifted inactivation voltage dependence to more negative potentials. These effects, which are not fully rescued by coexpression of wild-type and mutant KCNA2 subunits, probably result from the enhancement of VSD function, as demonstrated by optically tracking VSD depolarization-evoked conformational rearrangements. In turn, molecular dynamics simulations suggest altered VSD exposure to membrane lipids. Compared to other encephalopathy patients with KCNA2 mutations, the proband exhibits mild neurological impairment, more characteristic of patients with KCNA2 loss of function. Based on this information, we propose a mechanism of epileptogenesis based on enhanced KV1.2 inactivation leading to increased synaptic release preferentially in excitatory neurons, and hence the perturbation of the excitatory/inhibitory balance of neuronal circuits.
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Affiliation(s)
- Antonios Pantazis
- Division of Molecular Medicine, Department of Anesthesiology & Perioperative Medicine, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, CA, USA
- Division of Neurobiology, Department of Biomedical and Clinical Sciences (BKV), Linköping University, Linköping, Sweden
- Wallenberg Center for Molecular Medicine, Linköping University, Linköping, Sweden
| | - Maki Kaneko
- Center for Personalized Medicine, Children's Hospital, Los Angeles, Los Angeles, CA, USA
- Division of Genomic Medicine, Department of Pathology, Children's Hospital Los Angeles, Los Angeles, CA, USA
| | - Marina Angelini
- Division of Molecular Medicine, Department of Anesthesiology & Perioperative Medicine, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, CA, USA
| | - Federica Steccanella
- Division of Molecular Medicine, Department of Anesthesiology & Perioperative Medicine, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, CA, USA
| | - Annie M Westerlund
- Science for Life Laboratory, Department of Applied Physics, KTH Royal Institute of Technology, Solna, Sweden
| | - Sarah H Lindström
- Division of Neurobiology, Department of Biomedical and Clinical Sciences (BKV), Linköping University, Linköping, Sweden
| | - Michelle Nilsson
- Division of Neurobiology, Department of Biomedical and Clinical Sciences (BKV), Linköping University, Linköping, Sweden
| | - Lucie Delemotte
- Science for Life Laboratory, Department of Applied Physics, KTH Royal Institute of Technology, Solna, Sweden
| | - Sulagna C Saitta
- Department of Obstetrics and Gynecology and Division of Medical Genetics, Department of Pediatrics, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, CA, USA
| | - Riccardo Olcese
- Division of Molecular Medicine, Department of Anesthesiology & Perioperative Medicine, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, CA, USA
- Department of Physiology, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, CA, USA
- Brain Research Institute, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, CA, USA
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64
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Shore AN, Colombo S, Tobin WF, Petri S, Cullen ER, Dominguez S, Bostick CD, Beaumont MA, Williams D, Khodagholy D, Yang M, Lutz CM, Peng Y, Gelinas JN, Goldstein DB, Boland MJ, Frankel WN, Weston MC. Reduced GABAergic Neuron Excitability, Altered Synaptic Connectivity, and Seizures in a KCNT1 Gain-of-Function Mouse Model of Childhood Epilepsy. Cell Rep 2020; 33:108303. [PMID: 33113364 PMCID: PMC7712469 DOI: 10.1016/j.celrep.2020.108303] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Revised: 08/06/2020] [Accepted: 10/01/2020] [Indexed: 01/07/2023] Open
Abstract
Gain-of-function (GOF) variants in K+ channels cause severe childhood epilepsies, but there are no mechanisms to explain how increased K+ currents lead to network hyperexcitability. Here, we introduce a human Na+-activated K+ (KNa) channel variant (KCNT1-Y796H) into mice and, using a multiplatform approach, find motor cortex hyperexcitability and early-onset seizures, phenotypes strikingly similar to those of human patients. Although the variant increases KNa currents in cortical excitatory and inhibitory neurons, there is an increase in the KNa current across subthreshold voltages only in inhibitory neurons, particularly in those with non-fast-spiking properties, resulting in inhibitory-neuron-specific impairments in excitability and action potential (AP) generation. We further observe evidence of synaptic rewiring, including increases in homotypic synaptic connectivity, accompanied by network hyperexcitability and hypersynchronicity. These findings support inhibitory-neuron-specific mechanisms in mediating the epileptogenic effects of KCNT1 channel GOF, offering cell-type-specific currents and effects as promising targets for therapeutic intervention.
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Affiliation(s)
- Amy N Shore
- Department of Neurological Sciences, University of Vermont, Burlington, VT 05405, USA
| | - Sophie Colombo
- Institute for Genomic Medicine, Columbia University, New York, NY 10032, USA
| | - William F Tobin
- Department of Neurological Sciences, University of Vermont, Burlington, VT 05405, USA
| | - Sabrina Petri
- Institute for Genomic Medicine, Columbia University, New York, NY 10032, USA
| | - Erin R Cullen
- Department of Neurological Sciences, University of Vermont, Burlington, VT 05405, USA
| | - Soledad Dominguez
- Institute for Genomic Medicine, Columbia University, New York, NY 10032, USA
| | | | - Michael A Beaumont
- Institute for Genomic Medicine, Columbia University, New York, NY 10032, USA; Axion BioSystems, Atlanta, GA 30309, USA
| | - Damian Williams
- Institute for Genomic Medicine, Columbia University, New York, NY 10032, USA
| | - Dion Khodagholy
- Department of Electrical Engineering, Columbia University, New York, NY 10032, USA
| | - Mu Yang
- Institute for Genomic Medicine, Columbia University, New York, NY 10032, USA
| | | | - Yueqing Peng
- Institute for Genomic Medicine, Columbia University, New York, NY 10032, USA; Department of Pathology and Cell Biology, Columbia University, New York, NY 10032, USA
| | - Jennifer N Gelinas
- Institute for Genomic Medicine, Columbia University, New York, NY 10032, USA; Department of Neurology, Columbia University, New York, NY 10032, USA
| | - David B Goldstein
- Institute for Genomic Medicine, Columbia University, New York, NY 10032, USA; Department of Genetics and Development, Columbia University, New York, NY 10032, USA
| | - Michael J Boland
- Institute for Genomic Medicine, Columbia University, New York, NY 10032, USA; Department of Genetics and Development, Columbia University, New York, NY 10032, USA
| | - Wayne N Frankel
- Institute for Genomic Medicine, Columbia University, New York, NY 10032, USA; Department of Neurology, Columbia University, New York, NY 10032, USA
| | - Matthew C Weston
- Department of Neurological Sciences, University of Vermont, Burlington, VT 05405, USA.
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65
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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: 22] [Impact Index Per Article: 5.5] [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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66
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Liu J, Qu C, Han C, Chen MM, An LJ, Zou W. Potassium channels and their role in glioma: A mini review. Mol Membr Biol 2020; 35:76-85. [PMID: 32067536 DOI: 10.1080/09687688.2020.1729428] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
K+ channels regulate a multitude of biological processes and play important roles in a variety of diseases by controlling potassium flow across cell membranes. They are widely expressed in the central and peripheral nervous system. As a malignant tumor derived from nerve epithelium, glioma has the characteristics of high incidence, high recurrence rate, high mortality rate, and low cure rate. Since glioma cells show invasive growth, current surgical methods cannot completely remove tumors. Adjuvant chemotherapy is still needed after surgery. Because the blood-brain barrier and other factors lead to a lower effective concentration of chemotherapeutic drugs in the tumor, the recurrence rate of residual lesions is extremely high. Therefore, new therapeutic methods are needed. Numerous studies have shown that different K+ channel subtypes are differentially expressed in glioma cells and are involved in the regulation of the cell cycle of glioma cells to arrest them at different stages of the cell cycle. Increasing evidence suggests that K+ channels express in glioma cells and regulate glioma cell behaviors such as cell cycle, proliferation and apoptosis. This review article aims to summarize the current knowledge on the function of K+ channels in glioma, suggests K+ channels participating in the development of glioma.
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Affiliation(s)
- Jia Liu
- School of Life Science and Biotechnology, Faculty of Chemical, Environmental and Biological Science, Technology, Dalian University of Technology, Dalian, China.,College of Life Science, Liaoning Normal University, Dalian, China
| | - Chao Qu
- College of Life Science, Liaoning Normal University, Dalian, China
| | - Chao Han
- Regenerative Medicine Center, First Affiliated Hospital of Dalian Medical University, Dalian, China
| | - Meng-Meng Chen
- Company of Qingdao Re-Store Life Sciences, Qingdao, China
| | - Li-Jia An
- School of Life Science and Biotechnology, Faculty of Chemical, Environmental and Biological Science, Technology, Dalian University of Technology, Dalian, China
| | - Wei Zou
- College of Life Science, Liaoning Normal University, Dalian, China.,Company of Qingdao Re-Store Life Sciences, Qingdao, China
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67
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Nappi P, Miceli F, Soldovieri MV, Ambrosino P, Barrese V, Taglialatela M. Epileptic channelopathies caused by neuronal Kv7 (KCNQ) channel dysfunction. Pflugers Arch 2020; 472:881-898. [PMID: 32506321 DOI: 10.1007/s00424-020-02404-2] [Citation(s) in RCA: 50] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2020] [Revised: 05/12/2020] [Accepted: 05/18/2020] [Indexed: 11/28/2022]
Abstract
Seizures are the most common neurological manifestation in the newborn period, with an estimated incidence of 1.8-3.5 per 1000 live births. Prolonged or intractable seizures have a detrimental effect on cognition and brain function in experimental animals and are associated with adverse long-term neurodevelopmental sequelae and an increased risk of post-neonatal epilepsy in humans. The developing brain is particularly susceptible to the potentially severe effects of epilepsy, and epilepsy, especially when refractory to medications, often results in a developmental and epileptic encephalopathy (DEE) with developmental arrest or regression. DEEs can be primarily attributed to genetic causes. Given the critical role of potassium (K+) currents with distinct subcellular localization, biophysical properties, modulation, and pharmacological profile in regulating intrinsic electrical properties of neurons and their responsiveness to synaptic inputs, it is not too surprising that genetic research in the past two decades has identified several K+ channel genes as responsible for a large fraction of DEE. In the present article, we review the genetically determined epileptic channelopathies affecting three members of the Kv7 family, namely Kv7.2 (KCNQ2), Kv7.3 (KCNQ3), and Kv7.5 (KCNQ5); we review the phenotypic spectrum of Kv7-related epileptic channelopathies, the different genetic and pathogenetic mechanisms, and the emerging genotype-phenotype correlations which may prove crucial for prognostic predictions, disease management, parental counseling, and individually tailored therapeutic attempts.
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Affiliation(s)
- Piera Nappi
- Section of Pharmacology, Department of Neuroscience, University of Naples, "Federico II", Via Pansini 5, 80131, Naples, Italy
| | - Francesco Miceli
- Section of Pharmacology, Department of Neuroscience, University of Naples, "Federico II", Via Pansini 5, 80131, Naples, Italy
| | | | - Paolo Ambrosino
- Department of Science and Technology (DST), University of Sannio, Benevento, Italy
| | - Vincenzo Barrese
- Section of Pharmacology, Department of Neuroscience, University of Naples, "Federico II", Via Pansini 5, 80131, Naples, Italy
| | - Maurizio Taglialatela
- Section of Pharmacology, Department of Neuroscience, University of Naples, "Federico II", Via Pansini 5, 80131, Naples, Italy.
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68
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D'Adamo MC, Liantonio A, Conte E, Pessia M, Imbrici P. Ion Channels Involvement in Neurodevelopmental Disorders. Neuroscience 2020; 440:337-359. [PMID: 32473276 DOI: 10.1016/j.neuroscience.2020.05.032] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Revised: 05/16/2020] [Accepted: 05/19/2020] [Indexed: 12/14/2022]
Abstract
Inherited and sporadic mutations in genes encoding for brain ion channels, affecting membrane expression or biophysical properties, have been associated with neurodevelopmental disorders characterized by epilepsy, cognitive and behavioral deficits with significant phenotypic and genetic heterogeneity. Over the years, the screening of a growing number of patients and the functional characterization of newly identified mutations in ion channels genes allowed to recognize new phenotypes and to widen the clinical spectrum of known diseases. Furthermore, advancements in understanding disease pathogenesis at atomic level or using patient-derived iPSCs and animal models have been pivotal to orient therapeutic intervention and to put the basis for the development of novel pharmacological options for drug-resistant disorders. In this review we will discuss major improvements and critical issues concerning neurodevelopmental disorders caused by dysfunctions in brain sodium, potassium, calcium, chloride and ligand-gated ion channels.
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Affiliation(s)
- Maria Cristina D'Adamo
- Department of Physiology and Biochemistry, Faculty of Medicine and Surgery, University of Malta, Malta
| | | | - Elena Conte
- Department of Pharmacy-Drug Sciences, University of Bari "Aldo Moro", Italy
| | - Mauro Pessia
- Department of Physiology and Biochemistry, Faculty of Medicine and Surgery, University of Malta, Malta; Department of Physiology, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates
| | - Paola Imbrici
- Department of Pharmacy-Drug Sciences, University of Bari "Aldo Moro", Italy.
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69
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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: 10] [Impact Index Per Article: 2.5] [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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70
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von Wittgenstein J, Zheng F, Wittmann MT, Balta EA, Ferrazzi F, Schäffner I, Häberle BM, Valero-Aracama MJ, Koehl M, Miranda CJ, Kaspar BK, Ekici AB, Reis A, Abrous DN, Alzheimer C, Lie DC. Sox11 is an Activity-Regulated Gene with Dentate-Gyrus-Specific Expression Upon General Neural Activation. Cereb Cortex 2020; 30:3731-3743. [PMID: 32080705 DOI: 10.1093/cercor/bhz338] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2019] [Revised: 06/25/2019] [Accepted: 07/04/2019] [Indexed: 01/21/2023] Open
Abstract
Neuronal activity initiates transcriptional programs that shape long-term changes in plasticity. Although neuron subtypes differ in their plasticity response, most activity-dependent transcription factors (TFs) are broadly expressed across neuron subtypes and brain regions. Thus, how region- and neuronal subtype-specific plasticity are established on the transcriptional level remains poorly understood. We report that in young adult (i.e., 6-8 weeks old) mice, the developmental TF SOX11 is induced in neurons within 6 h either by electroconvulsive stimulation or by exploration of a novel environment. Strikingly, SOX11 induction was restricted to the dentate gyrus (DG) of the hippocampus. In the novel environment paradigm, SOX11 was observed in a subset of c-FOS expressing neurons (ca. 15%); whereas around 75% of SOX11+ DG granule neurons were c-FOS+, indicating that SOX11 was induced in an activity-dependent fashion in a subset of neurons. Environmental enrichment or virus-mediated overexpression of SOX11 enhanced the excitability of DG granule cells and downregulated the expression of different potassium channel subunits, whereas conditional Sox11/4 knock-out mice presented the opposite phenotype. We propose that Sox11 is regulated in an activity-dependent fashion, which is specific to the DG, and speculate that activity-dependent Sox11 expression may participate in the modulation of DG neuron plasticity.
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Affiliation(s)
- Julia von Wittgenstein
- Institute of Biochemistry, Emil Fischer Center, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054 Erlangen, Germany.,Department of Biology, Animal Physiology, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91058 Erlangen, Germany
| | - Fang Zheng
- Institute of Physiology and Pathophysiology, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054 Erlangen, Germany
| | - Marie-Theres Wittmann
- Institute of Biochemistry, Emil Fischer Center, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054 Erlangen, Germany.,Institute of Human Genetics, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054 Erlangen, Germany
| | - Elli-Anna Balta
- Institute of Biochemistry, Emil Fischer Center, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054 Erlangen, Germany
| | - Fulvia Ferrazzi
- Institute of Human Genetics, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054 Erlangen, Germany
| | - Iris Schäffner
- Institute of Biochemistry, Emil Fischer Center, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054 Erlangen, Germany
| | - Benjamin M Häberle
- Institute of Biochemistry, Emil Fischer Center, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054 Erlangen, Germany
| | - Maria J Valero-Aracama
- Institute of Physiology and Pathophysiology, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054 Erlangen, Germany
| | - Muriel Koehl
- Neurocentre Magendie U1215, INSERM and Université de Bordeaux, Bordeaux 33000, France
| | - Carlos J Miranda
- The Research Institute, Nationwide Children's Hospital, Columbus, OH 43205, USA
| | - Brian K Kaspar
- The Research Institute, Nationwide Children's Hospital, Columbus, OH 43205, USA
| | - Arif B Ekici
- Institute of Human Genetics, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054 Erlangen, Germany
| | - André Reis
- Institute of Human Genetics, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054 Erlangen, Germany
| | - Djoher Nora Abrous
- Neurocentre Magendie U1215, INSERM and Université de Bordeaux, Bordeaux 33000, France
| | - Christian Alzheimer
- Institute of Physiology and Pathophysiology, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054 Erlangen, Germany
| | - D Chichung Lie
- Institute of Biochemistry, Emil Fischer Center, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054 Erlangen, Germany
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71
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Zhang J, Kim EC, Chen C, Procko E, Pant S, Lam K, Patel J, Choi R, Hong M, Joshi D, Bolton E, Tajkhorshid E, Chung HJ. Identifying mutation hotspots reveals pathogenetic mechanisms of KCNQ2 epileptic encephalopathy. Sci Rep 2020; 10:4756. [PMID: 32179837 PMCID: PMC7075958 DOI: 10.1038/s41598-020-61697-6] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Accepted: 03/02/2020] [Indexed: 11/08/2022] Open
Abstract
Kv7 channels are enriched at the axonal plasma membrane where their voltage-dependent potassium currents suppress neuronal excitability. Mutations in Kv7.2 and Kv7.3 subunits cause epileptic encephalopathy (EE), yet the underlying pathogenetic mechanism is unclear. Here, we used novel statistical algorithms and structural modeling to identify EE mutation hotspots in key functional domains of Kv7.2 including voltage sensing S4, the pore loop and S6 in the pore domain, and intracellular calmodulin-binding helix B and helix B-C linker. Characterization of selected EE mutations from these hotspots revealed that L203P at S4 induces a large depolarizing shift in voltage dependence of Kv7.2 channels and L268F at the pore decreases their current densities. While L268F severely reduces expression of heteromeric channels in hippocampal neurons without affecting internalization, K552T and R553L mutations at distal helix B decrease calmodulin-binding and axonal enrichment. Importantly, L268F, K552T, and R553L mutations disrupt current potentiation by increasing phosphatidylinositol 4,5-bisphosphate (PIP2), and our molecular dynamics simulation suggests PIP2 interaction with these residues. Together, these findings demonstrate that each EE variant causes a unique combination of defects in Kv7 channel function and neuronal expression, and suggest a critical need for both prediction algorithms and experimental interrogations to understand pathophysiology of Kv7-associated EE.
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Affiliation(s)
- Jiaren Zhang
- Department of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801, USA
| | - Eung Chang Kim
- Department of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801, USA
| | - Congcong Chen
- Department of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801, USA
- Department of Statistics, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801, USA
| | - Erik Procko
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801, USA
- Neuroscience Program, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801, USA
| | - Shashank Pant
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801, USA
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801, USA
- Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801, USA
| | - Kin Lam
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801, USA
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801, USA
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801, USA
| | - Jaimin Patel
- Department of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801, USA
| | - Rebecca Choi
- Department of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801, USA
| | - Mary Hong
- Department of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801, USA
| | - Dhruv Joshi
- Department of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801, USA
| | - Eric Bolton
- Department of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801, USA
| | - Emad Tajkhorshid
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801, USA
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801, USA
- Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801, USA
| | - Hee Jung Chung
- Department of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801, USA.
- Neuroscience Program, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801, USA.
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72
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Borlot F, Abushama A, Morrison-Levy N, Jain P, Puthenveettil Vinayan K, Abukhalid M, Aldhalaan HM, Almuzaini HS, Gulati S, Hershkovitz T, Konanki R, Lingappa L, Luat AF, Shafi S, Tabarki B, Thomas M, Yoganathan S, Alfadhel M, Arya R, Donner EJ, Ehaideb SN, Gowda VK, Jain V, Madaan P, Myers KA, Otsubo H, Panda P, Sahu JK, Sampaio LPB, Sharma S, Simard-Tremblay E, Zak M, Whitney R. KCNT1-related epilepsy: An international multicenter cohort of 27 pediatric cases. Epilepsia 2020; 61:679-692. [PMID: 32167590 DOI: 10.1111/epi.16480] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Revised: 02/02/2020] [Accepted: 02/24/2020] [Indexed: 12/19/2022]
Abstract
OBJECTIVE Through international collaboration, we evaluated the phenotypic aspects of a multiethnic cohort of KCNT1-related epilepsy and explored genotype-phenotype correlations associated with frequently encountered variants. METHODS A cross-sectional analysis of children harboring pathogenic or likely pathogenic KCNT1 variants was completed. Children with one of the two more common recurrent KCNT1 variants were compared with the rest of the cohort for the presence of particular characteristics. RESULTS Twenty-seven children (15 males, mean age = 40.8 months) were included. Seizure onset ranged from 1 day to 6 months, and half (48.1%) exhibited developmental plateauing upon onset. Two-thirds had epilepsy of infancy with migrating focal seizures (EIMFS), and focal tonic seizures were common (48.1%). The most frequent recurrent KCNT1 variants were c.2800G>A; p.Ala934Thr (n = 5) and c.862G>A; p.Gly288Ser (n = 4). De novo variants were found in 96% of tested parents (23/24). Sixty percent had abnormal magnetic resonance imaging (MRI) findings. Delayed myelination, thin corpus callosum, and brain atrophy were the most common. One child had gray-white matter interface indistinctness, suggesting a malformation of cortical development. Several antiepileptic drugs (mean = 7.4/patient) were tried, with no consistent response to any one agent. Eleven tried quinidine; 45% had marked (>50% seizure reduction) or some improvement (25%-50% seizure reduction). Seven used cannabidiol; 71% experienced marked or some improvement. Fourteen tried diet therapies; 57% had marked or some improvement. When comparing the recurrent variants to the rest of the cohort with respect to developmental trajectory, presence of EIMFS, >500 seizures/mo, abnormal MRI, and treatment response, there were no statistically significant differences. Four patients died (15%), none of sudden unexpected death in epilepsy. SIGNIFICANCE Our cohort reinforces common aspects of this highly pleiotropic entity. EIMFS manifesting with refractory tonic seizures was the most common. Cannabidiol, diet therapy, and quinidine seem to offer the best chances of seizure reduction, although evidence-based practice is still unavailable.
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Affiliation(s)
- Felippe Borlot
- Division of Neurology, Department of Paediatrics, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Ahmed Abushama
- Division of Neurology, Department of Paediatrics, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Nadine Morrison-Levy
- Division of Neurology, Department of Paediatrics, The Hospital for Sick Children, Toronto, Ontario, Canada.,Children's Hospital of Eastern Ottawa, Ottawa, Ontario, Canada
| | - Puneet Jain
- Division of Neurology, Department of Paediatrics, The Hospital for Sick Children, Toronto, Ontario, Canada.,Division of Pediatric Neurology, Department of Pediatrics, Danat Al Emarat Hospital for Women and Children, Abu Dhabi, United Arab Emirates
| | | | - Musaad Abukhalid
- Department of Neurosciences, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - Hesham M Aldhalaan
- Department of Neurosciences, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - Hanin S Almuzaini
- Department of Neurosciences, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - Sheffali Gulati
- Child Neurology Division, Department of Pediatrics, Center of Excellence & Advanced Research on Childhood Neurodevelopmental Disorders, All India Institute of Medical Sciences, New Delhi, India
| | | | - Ramesh Konanki
- Department of Neurology, Rainbow Children's Hospital, Hyderabad, India
| | - Lokesh Lingappa
- Department of Neurology, Rainbow Children's Hospital, Hyderabad, India
| | - Aimee F Luat
- Detroit Medical Center, Children's Hospital of Michigan, Wayne State University School of Medicine, Detroit, Michigan
| | - Shatha Shafi
- Division of Neurology, Department of Pediatrics, Prince Sultan Military Medical City, Riyadh, Saudi Arabia
| | - Brahim Tabarki
- Division of Neurology, Department of Pediatrics, Prince Sultan Military Medical City, Riyadh, Saudi Arabia
| | - Maya Thomas
- Pediatric Neurology, Department of Neurological Sciences, Christian Medical College, Vellore, India
| | - Sangeetha Yoganathan
- Pediatric Neurology, Department of Neurological Sciences, Christian Medical College, Vellore, India
| | - Majid Alfadhel
- King Abdullah International Medical Research Center, King Saud bin Abdulaziz University for Health Sciences, King Abdulaziz Medical City, Ministry of National Guard-Health Affairs, Riyadh, Saudi Arabia.,Division of Genetics, Department of Pediatrics, King Abdulaziz Medical City, Ministry of National Guard-Health Affairs, Riyadh, Saudi Arabia
| | - Ravindra Arya
- Division of Neurology, Comprehensive Epilepsy Center, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio.,Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, Ohio
| | - Elizabeth J Donner
- Division of Neurology, Department of Paediatrics, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Salleh N Ehaideb
- King Abdullah International Medical Research Center, King Saud bin Abdulaziz University for Health Sciences, King Abdulaziz Medical City, Ministry of National Guard-Health Affairs, Riyadh, Saudi Arabia
| | | | - Vivek Jain
- Santokba Durlabhji Hospital, Jaipur, India
| | - Priyanka Madaan
- Pediatric Neurology Unit, Department of Pediatrics, Postgraduate Institute of Medical Education and Research, Chandigarh, India
| | - Kenneth A Myers
- Division of Neurology, Department of Pediatrics, Montreal Children's Hospital, McGill University Health Centre, Montreal, Quebec, Canada.,Department of Neurology & Neurosurgery, McGill University Health Centre, Montreal, Quebec, Canada.,Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada
| | - Hiroshi Otsubo
- Division of Neurology, Department of Paediatrics, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Prateek Panda
- Child Neurology Division, Department of Pediatrics, Center of Excellence & Advanced Research on Childhood Neurodevelopmental Disorders, All India Institute of Medical Sciences, New Delhi, India
| | - Jitendra K Sahu
- Pediatric Neurology Unit, Department of Pediatrics, Postgraduate Institute of Medical Education and Research, Chandigarh, India
| | - Letícia P B Sampaio
- Department of Neurology, Faculty of Medicine, University of Sao Paulo, Sao Paulo, Brazil
| | - Suvasini Sharma
- Neurology Division, Department of Pediatrics, Lady Harding Medical College and Kalawati Saran Children's Hospital, New Delhi, India
| | - Elisabeth Simard-Tremblay
- Division of Neurology, Department of Pediatrics, Montreal Children's Hospital, McGill University Health Centre, Montreal, Quebec, Canada.,Department of Neurology & Neurosurgery, McGill University Health Centre, Montreal, Quebec, Canada
| | - Maria Zak
- Division of Neurology, Department of Paediatrics, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Robyn Whitney
- Division of Neurology, Department of Paediatrics, The Hospital for Sick Children, Toronto, Ontario, Canada
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73
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Mao X, Bruneau N, Gao Q, Becq H, Jia Z, Xi H, Shu L, Wang H, Szepetowski P, Aniksztejn L. The Epilepsy of Infancy With Migrating Focal Seizures: Identification of de novo Mutations of the KCNT2 Gene That Exert Inhibitory Effects on the Corresponding Heteromeric K Na1.1/K Na1.2 Potassium Channel. Front Cell Neurosci 2020; 14:1. [PMID: 32038177 PMCID: PMC6992647 DOI: 10.3389/fncel.2020.00001] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Accepted: 01/06/2020] [Indexed: 12/21/2022] Open
Abstract
The epilepsy of infancy with migrating focal seizures (EIMFS; previously called Malignant migrating partial seizures of infancy) are early-onset epileptic encephalopathies (EOEE) that associate multifocal ictal discharges and profound psychomotor retardation. EIMFS have a genetic origin and are mostly caused by de novo mutations in the KCNT1 gene, and much more rarely in the KCNT2 gene. KCNT1 and KCNT2 respectively encode the KNa1.1 (Slack) and KNa1.2 (Slick) subunits of the sodium-dependent voltage-gated potassium channel KNa. Functional analyses of the corresponding mutant homomeric channels in vitro suggested gain-of-function effects. Here, we report two novel, de novo truncating mutations of KCNT2: one mutation is frameshift (p.L48Qfs43), is situated in the N-terminal domain, and was found in a patient with EOEE (possibly EIMFS); the other mutation is nonsense (p.K564*), is located in the C-terminal region, and was found in a typical EIMFS patient. Using whole-cell patch-clamp recordings, we have analyzed the functional consequences of those two novel KCNT2 mutations on reconstituted KNa1.2 homomeric and KNa1.1/KNa1.2 heteromeric channels in transfected chinese hamster ovary (CHO) cells. We report that both mutations significantly impacted on KNa function; notably, they decreased the global current density of heteromeric channels by ~25% (p.K564*) and ~55% (p.L48Qfs43). Overall our data emphasize the involvement of KCNT2 in EOEE and provide novel insights into the role of heteromeric KNa channel in the severe KCNT2-related epileptic phenotypes. This may have important implications regarding the elaboration of future treatment.
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Affiliation(s)
- Xiao Mao
- Hunan Provincial Maternal and Child Health Care Hospital, Changsha, China
- NHC Key Laboratory of Birth Defects Research, Prevention and Treatment, Changsha, China
| | - Nadine Bruneau
- INSERM, Aix-Marseille University, INMED, UMR1249, Marseille, France
| | - Quwen Gao
- Department of Epilepsy, General Hospital of Southern Theater Command, Guangzhou, China
| | - Hélène Becq
- INSERM, Aix-Marseille University, INMED, UMR1249, Marseille, France
| | - Zhengjun Jia
- Hunan Provincial Maternal and Child Health Care Hospital, Changsha, China
- NHC Key Laboratory of Birth Defects Research, Prevention and Treatment, Changsha, China
| | - Hui Xi
- Hunan Provincial Maternal and Child Health Care Hospital, Changsha, China
- NHC Key Laboratory of Birth Defects Research, Prevention and Treatment, Changsha, China
| | - Li Shu
- Hunan Provincial Maternal and Child Health Care Hospital, Changsha, China
- NHC Key Laboratory of Birth Defects Research, Prevention and Treatment, Changsha, China
| | - Hua Wang
- Hunan Provincial Maternal and Child Health Care Hospital, Changsha, China
- NHC Key Laboratory of Birth Defects Research, Prevention and Treatment, Changsha, China
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74
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Allen NM, Weckhuysen S, Gorman K, King MD, Lerche H. Genetic potassium channel-associated epilepsies: Clinical review of the K v family. Eur J Paediatr Neurol 2020; 24:105-116. [PMID: 31932120 DOI: 10.1016/j.ejpn.2019.12.002] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Accepted: 12/06/2019] [Indexed: 12/22/2022]
Abstract
Next-generation sequencing has enhanced discovery of many disease-associated genes in previously unexplained epilepsies, mainly in developmental and epileptic encephalopathies and familial epilepsies. We now classify these disorders according to the underlying molecular pathways, which encompass a diverse array of cellular and sub-cellular compartments/signalling processes including voltage-gated ion-channel defects. With the aim to develop and increase the use of precision medicine therapies, understanding the pathogenic mechanisms and consequences of disease-causing variants has gained major relevance in clinical care. The super-family of voltage-gated potassium channels is the largest and most diverse family among the ion channels, encompassing approximately 80 genes. Key potassium channelopathies include those affecting the KV, KCa and Kir families, a significant proportion of which have been implicated in neurological disease. As for other ion channel disorders, different pathogenic variants within any individual voltage-gated potassium channel gene tend to affect channel protein function differently, causing heterogeneous clinical phenotypes. The focus of this review is to summarise recent clinical developments regarding the key voltage-gated potassium (KV) family-related epilepsies, which now encompasses approximately 12 established disease-associated genes, from the KCNA-, KCNB-, KCNC-, KCND-, KCNV-, KCNQ- and KCNH-subfamilies.
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Affiliation(s)
- Nicholas M Allen
- Department of Paediatrics, National University of Ireland, Galway, Ireland; Department of Paediatrics (Neurology), Galway University Hospital, Ireland; Regenerative Medicine Institute (REMEDI), National University of Ireland, Galway, Ireland.
| | - Sarah Weckhuysen
- Neurogenetics Group, Center for Molecular Neurology, VIB-University of Antwerp, Antwerp, Belgium; Department of Neurology, University Hospital Antwerp, Antwerp, Belgium
| | - Kathleen Gorman
- Department of Paediatric Neurology & Clinical Neurophysiology, Children's Health Ireland at Temple Street, Dublin 1, Ireland; University College Dublin School of Medicine and Medical Science, University College, Dublin, Ireland
| | - Mary D King
- Department of Paediatric Neurology & Clinical Neurophysiology, Children's Health Ireland at Temple Street, Dublin 1, Ireland; University College Dublin School of Medicine and Medical Science, University College, Dublin, Ireland
| | - Holger Lerche
- Department of Neurology and Epileptology, Hertie Institute of Clinical Brain Research, University of Tubingen, Germany
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75
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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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76
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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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Li BG, Wu WJ, Zheng HC, Yang HF, Zuo YX, Cui XP. Long noncoding RNA GAS5 silencing inhibits the expression of KCNQ3 by sponging miR-135a-5p to prevent the progression of epilepsy. Kaohsiung J Med Sci 2019; 35:527-534. [PMID: 31373759 DOI: 10.1002/kjm2.12102] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Accepted: 06/03/2019] [Indexed: 02/06/2023] Open
Abstract
Epilepsy is one of the most common neurological disorders in humans. Recently, long noncoding RNAs (lncRNAs) have been reported to be important players in neurological diseases. Herein, this study aimed to examine the effect of lncRNA GAS5 on the occurrence of epilepsy in rat and cell models of epileptic seizure. The expression of lncRNA GAS5 was measured in the established rat and cell models. The binding sites between lncRNA GAS5 and miR-135a-5p, as well as those between miR-135a-5p and 3' untranslated region of KCNQ3 were predicted by miRDB and Targetscan, separately, followed by verification using dual-luciferase reporter gene assay. The expression of miR-135a-5p was measured in response to the overexpression of lncRNA GAS5. The mRNA and protein levels of KCNQ3 were examined in response to overexpression of miR-135a-5p. Next, the latency of epilepsy and frequency of epileptic seizures were assessed in rats injected with Lv-shGAS5 and Lv-miR-135a-5p in epileptic seizure model. In the rat and cell models, lncRNA GAS5 was highly expressed when epileptic seizure was induced. The expression of miR-135a-5p was decreased by overexpression of lncRNA GAS5. Meanwhile, the mRNA and protein levels of KCNQ3 were decreased in response to knockdown of miR-135a-5p. After the treatment of Lv-shGAS5 and Lv-miR-135a-5p, the average latent period of epilepsy was prolonged and the frequency of seizures was decreased. The key findings of the present study provide evidence emphasizing that lncRNA GAS5 functions as a competitive endogenous RNA of miR-135a-5p to increase expression of KCNQ3, and lncRNA GAS5 silencing inhibited the occurrence and progression of epilepsy.
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Affiliation(s)
- Bao-Guang Li
- Department of Neurology, Children's Hospital of Hebei Province, Shijiazhuang, Hebei, China
| | - Wen-Juan Wu
- Department of Neurology, Children's Hospital of Hebei Province, Shijiazhuang, Hebei, China
| | - Hua-Cheng Zheng
- Department of Neurology, Children's Hospital of Hebei Province, Shijiazhuang, Hebei, China
| | - Hua-Fang Yang
- Department of Neurology, Children's Hospital of Hebei Province, Shijiazhuang, Hebei, China
| | - Yue-Xian Zuo
- Department of Neurology, Children's Hospital of Hebei Province, Shijiazhuang, Hebei, China
| | - Xiao-Pu Cui
- Department of Neurology, Children's Hospital of Hebei Province, Shijiazhuang, Hebei, China
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78
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Kim EC, Patel J, Zhang J, Soh H, Rhodes JS, Tzingounis AV, Chung HJ. Heterozygous loss of epilepsy gene KCNQ2 alters social, repetitive and exploratory behaviors. GENES BRAIN AND BEHAVIOR 2019; 19:e12599. [PMID: 31283873 PMCID: PMC7050516 DOI: 10.1111/gbb.12599] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Revised: 06/28/2019] [Accepted: 07/06/2019] [Indexed: 12/28/2022]
Abstract
KCNQ/Kv7 channels conduct voltage‐dependent outward potassium currents that potently decrease neuronal excitability. Heterozygous inherited mutations in their principle subunits Kv7.2/KCNQ2 and Kv7.3/KCNQ3 cause benign familial neonatal epilepsy whereas patients with de novo heterozygous Kv7.2 mutations are associated with early‐onset epileptic encephalopathy and neurodevelopmental disorders characterized by intellectual disability, developmental delay and autism. However, the role of Kv7.2‐containing Kv7 channels in behaviors especially autism‐associated behaviors has not been described. Because pathogenic Kv7.2 mutations in patients are typically heterozygous loss‐of‐function mutations, we investigated the contributions of Kv7.2 to exploratory, social, repetitive and compulsive‐like behaviors by behavioral phenotyping of both male and female KCNQ2+/− mice that were heterozygous null for the KCNQ2 gene. Compared with their wild‐type littermates, male and female KCNQ2+/− mice displayed increased locomotor activity in their home cage during the light phase but not the dark phase and showed no difference in motor coordination, suggesting hyperactivity during the inactive light phase. In the dark phase, KCNQ2+/− group showed enhanced exploratory behaviors, and repetitive grooming but decreased sociability with sex differences in the degree of these behaviors. While male KCNQ2+/− mice displayed enhanced compulsive‐like behavior and social dominance, female KCNQ2+/− mice did not. In addition to elevated seizure susceptibility, our findings together indicate that heterozygous loss of Kv7.2 induces behavioral abnormalities including autism‐associated behaviors such as reduced sociability and enhanced repetitive behaviors. Therefore, our study is the first to provide a tangible link between loss‐of‐function Kv7.2 mutations and the behavioral comorbidities of Kv7.2‐associated epilepsy.
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Affiliation(s)
- Eung Chang Kim
- Department of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, Illinois
| | - Jaimin Patel
- Department of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, Illinois
| | - Jiaren Zhang
- Department of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, Illinois
| | - Heun Soh
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut
| | - Justin S Rhodes
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois.,Department of Psychology, University of Illinois at Urbana-Champaign, Urbana, Illinois.,Neuroscience Program, University of Illinois at Urbana-Champaign, Urbana, Illinois
| | | | - Hee Jung Chung
- Department of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, Illinois.,Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois.,Neuroscience Program, University of Illinois at Urbana-Champaign, Urbana, Illinois
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79
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Perucca P, Perucca E. Identifying mutations in epilepsy genes: Impact on treatment selection. Epilepsy Res 2019; 152:18-30. [DOI: 10.1016/j.eplepsyres.2019.03.001] [Citation(s) in RCA: 61] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2019] [Revised: 03/01/2019] [Accepted: 03/03/2019] [Indexed: 02/06/2023]
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80
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Shao LR, Habela CW, Stafstrom CE. Pediatric Epilepsy Mechanisms: Expanding the Paradigm of Excitation/Inhibition Imbalance. CHILDREN-BASEL 2019; 6:children6020023. [PMID: 30764523 PMCID: PMC6406372 DOI: 10.3390/children6020023] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Revised: 01/31/2019] [Accepted: 01/31/2019] [Indexed: 02/07/2023]
Abstract
Mechanisms underlying seizures and epilepsy have traditionally been considered to involve abnormalities of ion channels or synaptic function. Those considerations gave rise to the excitation/inhibition (E/I) imbalance theory, whereby increased excitation, decreased inhibition, or both favor a hyperexcitable state and an increased propensity for seizure generation and epileptogenesis. Several recent findings warrant reconsideration and expansion of the E/I hypothesis: novel genetic mutations have been identified that do not overtly affect E/I balance; neurotransmitters may exert paradoxical effects, especially during development; anti-seizure medications do not necessarily work by decreasing excitation or increasing inhibition; and metabolic factors participate in the regulation of neuronal and network excitability. These novel conceptual and experimental advances mandate expansion of the E/I paradigm, with the expectation that new and exciting therapies will emerge from this broadened understanding of how seizures and epilepsy arise and progress.
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Affiliation(s)
- Li-Rong Shao
- Division of Pediatric Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA.
| | - Christa W Habela
- Division of Pediatric Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA.
| | - Carl E Stafstrom
- Division of Pediatric Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA.
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81
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Barro-Soria R. Epilepsy-associated mutations in the voltage sensor of KCNQ3 affect voltage dependence of channel opening. J Gen Physiol 2018; 151:247-257. [PMID: 30578330 PMCID: PMC6363412 DOI: 10.1085/jgp.201812221] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Accepted: 12/03/2018] [Indexed: 11/20/2022] Open
Abstract
One of the major factors known to cause neuronal hyperexcitability is malfunction of the potassium channels formed by KCNQ2 and KCNQ3. These channel subunits underlie the M current, which regulates neuronal excitability. Here, I investigate the molecular mechanisms by which epilepsy-associated mutations in the voltage sensor (S4) of KCNQ3 cause channel malfunction. Voltage clamp fluorometry reveals that the R230C mutation in KCNQ3 allows S4 movement but shifts the open/closed transition of the gate to very negative potentials. This results in the mutated channel remaining open throughout the physiological voltage range. Substitution of R230 with natural and unnatural amino acids indicates that the functional effect of the arginine residue at position 230 depends on both its positive charge and the size of its side chain. I find that KCNQ3-R230C is hard to close, but it is capable of being closed at strong negative voltages. I suggest that compounds that shift the voltage dependence of S4 activation to more positive potentials would promote gate closure and thus have therapeutic potential.
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Affiliation(s)
- Rene Barro-Soria
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, Miller School of Medicine, University of Miami, Miami, FL
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82
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Soh H, Park S, Ryan K, Springer K, Maheshwari A, Tzingounis AV. Deletion of KCNQ2/3 potassium channels from PV+ interneurons leads to homeostatic potentiation of excitatory transmission. eLife 2018; 7:e38617. [PMID: 30382937 PMCID: PMC6211828 DOI: 10.7554/elife.38617] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Accepted: 10/19/2018] [Indexed: 12/18/2022] Open
Abstract
KCNQ2/3 channels, ubiquitously expressed neuronal potassium channels, have emerged as indispensable regulators of brain network activity. Despite their critical role in brain homeostasis, the mechanisms by which KCNQ2/3 dysfunction lead to hypersychrony are not fully known. Here, we show that deletion of KCNQ2/3 channels changed PV+ interneurons', but not SST+ interneurons', firing properties. We also find that deletion of either KCNQ2/3 or KCNQ2 channels from PV+ interneurons led to elevated homeostatic potentiation of fast excitatory transmission in pyramidal neurons. Pvalb-Kcnq2 null-mice showed increased seizure susceptibility, suggesting that decreases in interneuron KCNQ2/3 activity remodels excitatory networks, providing a new function for these channels.
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Affiliation(s)
- Heun Soh
- Department of Physiology and NeurobiologyUniversity of ConnecticutConnecticutUnited States
| | - Suhyeorn Park
- Department of NeurologyBaylor College of MedicineTexasUnited States
| | - Kali Ryan
- Department of Physiology and NeurobiologyUniversity of ConnecticutConnecticutUnited States
| | - Kristen Springer
- Department of Physiology and NeurobiologyUniversity of ConnecticutConnecticutUnited States
| | - Atul Maheshwari
- Department of NeurologyBaylor College of MedicineTexasUnited States
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83
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Baronas VA, Yang RY, Morales LC, Sipione S, Kurata HT. Slc7a5 regulates Kv1.2 channels and modifies functional outcomes of epilepsy-linked channel mutations. Nat Commun 2018; 9:4417. [PMID: 30356053 PMCID: PMC6200743 DOI: 10.1038/s41467-018-06859-x] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Accepted: 10/02/2018] [Indexed: 01/25/2023] Open
Abstract
Kv1.2 is a prominent voltage-gated potassium channel that influences action potential generation and propagation in the central nervous system. We explored multi-protein complexes containing Kv1.2 using mass spectrometry followed by screening for effects on Kv1.2. We report that Slc7a5, a neutral amino acid transporter, has a profound impact on Kv1.2. Co-expression with Slc7a5 reduces total Kv1.2 protein, and dramatically hyperpolarizes the voltage-dependence of activation by -47 mV. These effects are attenuated by expression of Slc3a2, a known binding partner of Slc7a5. The profound Slc7a5-mediated current suppression is partly explained by a combination of gating effects including accelerated inactivation and a hyperpolarizing shift of channel activation, causing channels to accumulate in a non-conducting state. Two recently reported Slc7a5 mutations linked to neurodevelopmental delay exhibit a localization defect and have attenuated effects on Kv1.2. In addition, epilepsy-linked gain-of-function Kv1.2 mutants exhibit enhanced sensitivity to Slc7a5.
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Affiliation(s)
- Victoria A Baronas
- Department of Pharmacology, University of Alberta, Edmonton, T6G 2R3, Canada
| | - Runying Y Yang
- Department of Pharmacology, University of Alberta, Edmonton, T6G 2R3, Canada
| | - Luis Carlos Morales
- Department of Pharmacology, University of Alberta, Edmonton, T6G 2R3, Canada
| | - Simonetta Sipione
- Department of Pharmacology, University of Alberta, Edmonton, T6G 2R3, Canada.,Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Canada
| | - Harley T Kurata
- Department of Pharmacology, University of Alberta, Edmonton, T6G 2R3, Canada. .,Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Canada. .,Alberta Diabetes Institute, University of Alberta, Edmonton, Canada.
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