1
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Aman TK, Raman IM. Resurgent current in context: Insights from the structure and function of Na and K channels. Biophys J 2023:S0006-3495(23)04154-1. [PMID: 38130058 DOI: 10.1016/j.bpj.2023.12.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2023] [Revised: 12/07/2023] [Accepted: 12/18/2023] [Indexed: 12/23/2023] Open
Abstract
Discovered just over 25 years ago in cerebellar Purkinje neurons, resurgent Na current was originally described operationally as a component of voltage-gated Na current that flows upon repolarization from relatively depolarized potentials and speeds recovery from inactivation, increasing excitability. Its presence in many excitable cells and absence from others has raised questions regarding its biophysical and molecular mechanisms. Early studies proposed that Na channels capable of generating resurgent current are subject to a rapid open-channel block by an endogenous blocking protein, which binds upon depolarization and unblocks upon repolarization. Since the time that this mechanism was suggested, many physiological and structural studies of both Na and K channels have revealed aspects of gating and conformational states that provide insights into resurgent current. These include descriptions of domain movements for activation and inactivation, solution of cryo-EM structures with pore-blocking compounds, and identification of native blocking domains, proteins, and modulatory subunits. Such results not only allow the open-channel block hypothesis to be refined but also link it more clearly to research that preceded it. This review considers possible mechanisms for resurgent Na current in the context of earlier and later studies of ion channels and suggests a framework for future research.
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Affiliation(s)
- Teresa K Aman
- Department of Neurobiology, Northwestern University, Evanston, Illinois
| | - Indira M Raman
- Department of Neurobiology, Northwestern University, Evanston, Illinois.
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2
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Angsutararux P, Dutta AK, Marras M, Abella C, Mellor RL, Shi J, Nerbonne JM, Silva JR. Differential regulation of cardiac sodium channels by intracellular fibroblast growth factors. J Gen Physiol 2023; 155:e202213300. [PMID: 36944081 PMCID: PMC10038838 DOI: 10.1085/jgp.202213300] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Revised: 01/17/2023] [Accepted: 02/09/2023] [Indexed: 03/23/2023] Open
Abstract
Voltage-gated sodium (NaV) channels are responsible for the initiation and propagation of action potentials. In the heart, the predominant NaV1.5 α subunit is composed of four homologous repeats (I-IV) and forms a macromolecular complex with multiple accessory proteins, including intracellular fibroblast growth factors (iFGF). In spite of high homology, each of the iFGFs, iFGF11-iFGF14, as well as the individual iFGF splice variants, differentially regulates NaV channel gating, and the mechanisms underlying these differential effects remain elusive. Much of the work exploring iFGF regulation of NaV1.5 has been performed in mouse and rat ventricular myocytes in which iFGF13VY is the predominant iFGF expressed, whereas investigation into NaV1.5 regulation by the human heart-dominant iFGF12B is lacking. In this study, we used a mouse model with cardiac-specific Fgf13 deletion to study the consequences of iFGF13VY and iFGF12B expression. We observed distinct effects on the voltage-dependences of activation and inactivation of the sodium currents (INa), as well as on the kinetics of peak INa decay. Results in native myocytes were recapitulated with human NaV1.5 heterologously expressed in Xenopus oocytes, and additional experiments using voltage-clamp fluorometry (VCF) revealed iFGF-specific effects on the activation of the NaV1.5 voltage sensor domain in repeat IV (VSD-IV). iFGF chimeras further unveiled roles for all three iFGF domains (i.e., the N-terminus, core, and C-terminus) on the regulation of VSD-IV, and a slower time domain of inactivation. We present here a novel mechanism of iFGF regulation that is specific to individual iFGF isoforms and that leads to distinct functional effects on NaV channel/current kinetics.
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Affiliation(s)
- Paweorn Angsutararux
- Department of Biomedical Engineering, McKelvey School of Engineering, Washington University in St. Louis, St. Louis, MO, USA
| | - Amal K. Dutta
- Department of Medicine, Cardiovascular Division, Washington University School of Medicine, St. Louis, MO, USA
| | - Martina Marras
- Department of Biomedical Engineering, McKelvey School of Engineering, Washington University in St. Louis, St. Louis, MO, USA
| | - Carlota Abella
- Department of Biomedical Engineering, McKelvey School of Engineering, Washington University in St. Louis, St. Louis, MO, USA
| | - Rebecca L. Mellor
- Department of Medicine, Cardiovascular Division, Washington University School of Medicine, St. Louis, MO, USA
| | - Jingyi Shi
- Department of Biomedical Engineering, McKelvey School of Engineering, Washington University in St. Louis, St. Louis, MO, USA
| | - Jeanne M. Nerbonne
- Department of Medicine, Cardiovascular Division, Washington University School of Medicine, St. Louis, MO, USA
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO, USA
| | - Jonathan R. Silva
- Department of Biomedical Engineering, McKelvey School of Engineering, Washington University in St. Louis, St. Louis, MO, USA
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3
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Brake N, Mancino AS, Yan Y, Shimomura T, Kubo Y, Khadra A, Bowie D. Closed-state inactivation of cardiac, skeletal, and neuronal sodium channels is isoform specific. J Gen Physiol 2022; 154:213242. [PMID: 35612552 PMCID: PMC9136305 DOI: 10.1085/jgp.202112921] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 05/09/2022] [Accepted: 05/12/2022] [Indexed: 01/07/2023] Open
Abstract
Voltage-gated sodium (Nav) channels produce the upstroke of action potentials in excitable tissues throughout the body. The gating of these channels is determined by the asynchronous movements of four voltage-sensing domains (VSDs). Past studies on the skeletal muscle Nav1.4 channel have indicated that VSD-I, -II, and -III are sufficient for pore opening, whereas VSD-IV movement is sufficient for channel inactivation. Here, we studied the cardiac sodium channel, Nav1.5, using charge-neutralizing mutations and voltage-clamp fluorometry. Our results reveal that both VSD-III and -IV are necessary for Nav1.5 inactivation, and that steady-state inactivation can be modulated by all VSDs. We also demonstrate that channel activation is partially determined by VSD-IV movement. Kinetic modeling suggests that these observations can be explained from the cardiac channel's propensity to enter closed-state inactivation (CSI), which is significantly higher than that of other Nav channels. We show that skeletal muscle Nav1.4, cardiac Nav1.5, and neuronal Nav1.6 all have different propensities for CSI and postulate that these differences produce isoform-dependent roles for the four VSDs.
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Affiliation(s)
- Niklas Brake
- Quantitative Life Sciences PhD Program, McGill University, Montreal, Quebec, Canada,Department of Physiology, McGill University, Montreal, Quebec, Canada
| | - Adamo S. Mancino
- Integrated Program in Neuroscience, McGill University, Montreal, Quebec, Canada,Department of Pharmacology and Therapeutics, McGill University, Montreal, Quebec, Canada
| | - Yuhao Yan
- Integrated Program in Neuroscience, McGill University, Montreal, Quebec, Canada,Department of Pharmacology and Therapeutics, McGill University, Montreal, Quebec, Canada
| | - Takushi Shimomura
- Division of Biophysics and Neurobiology, National Institute for Physiological Sciences, Okazaki, Japan,Department of Physiological Sciences, School of Life Science, The Graduate University for Advanced Studies (SOKENDAI), Hayama, Japan
| | - Yoshihiro Kubo
- Division of Biophysics and Neurobiology, National Institute for Physiological Sciences, Okazaki, Japan,Department of Physiological Sciences, School of Life Science, The Graduate University for Advanced Studies (SOKENDAI), Hayama, Japan
| | - Anmar Khadra
- Department of Physiology, McGill University, Montreal, Quebec, Canada
| | - Derek Bowie
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Quebec, Canada,Correspondence to Derek Bowie:
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4
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Daimi H, Lozano-Velasco E, Aranega A, Franco D. Genomic and Non-Genomic Regulatory Mechanisms of the Cardiac Sodium Channel in Cardiac Arrhythmias. Int J Mol Sci 2022; 23:1381. [PMID: 35163304 PMCID: PMC8835759 DOI: 10.3390/ijms23031381] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Revised: 12/30/2021] [Accepted: 01/06/2022] [Indexed: 12/19/2022] Open
Abstract
Nav1.5 is the predominant cardiac sodium channel subtype, encoded by the SCN5A gene, which is involved in the initiation and conduction of action potentials throughout the heart. Along its biosynthesis process, Nav1.5 undergoes strict genomic and non-genomic regulatory and quality control steps that allow only newly synthesized channels to reach their final membrane destination and carry out their electrophysiological role. These regulatory pathways are ensured by distinct interacting proteins that accompany the nascent Nav1.5 protein along with different subcellular organelles. Defects on a large number of these pathways have a tremendous impact on Nav1.5 functionality and are thus intimately linked to cardiac arrhythmias. In the present review, we provide current state-of-the-art information on the molecular events that regulate SCN5A/Nav1.5 and the cardiac channelopathies associated with defects in these pathways.
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Affiliation(s)
- Houria Daimi
- Biochemistry and Molecular Biology Laboratory, Faculty of Pharmacy, University of Monastir, Monastir 5000, Tunisia
| | - Estefanía Lozano-Velasco
- Department of Experimental Biology, University of Jaen, 23071 Jaen, Spain; (E.L.-V.); (A.A.); (D.F.)
- Medina Foundation, Technology Park of Health Sciences, Av. del Conocimiento, 34, 18016 Granada, Spain
| | - Amelia Aranega
- Department of Experimental Biology, University of Jaen, 23071 Jaen, Spain; (E.L.-V.); (A.A.); (D.F.)
- Medina Foundation, Technology Park of Health Sciences, Av. del Conocimiento, 34, 18016 Granada, Spain
| | - Diego Franco
- Department of Experimental Biology, University of Jaen, 23071 Jaen, Spain; (E.L.-V.); (A.A.); (D.F.)
- Medina Foundation, Technology Park of Health Sciences, Av. del Conocimiento, 34, 18016 Granada, Spain
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5
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Angsutararux P, Kang PW, Zhu W, Silva JR. Conformations of voltage-sensing domain III differentially define NaV channel closed- and open-state inactivation. J Gen Physiol 2021; 153:212533. [PMID: 34347027 PMCID: PMC8348240 DOI: 10.1085/jgp.202112891] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Accepted: 07/14/2021] [Indexed: 11/21/2022] Open
Abstract
Voltage-gated Na+ (NaV) channels underlie the initiation and propagation of action potentials (APs). Rapid inactivation after NaV channel opening, known as open-state inactivation, plays a critical role in limiting the AP duration. However, NaV channel inactivation can also occur before opening, namely closed-state inactivation, to tune the cellular excitability. The voltage-sensing domain (VSD) within repeat IV (VSD-IV) of the pseudotetrameric NaV channel α-subunit is known to be a critical regulator of NaV channel inactivation. Yet, the two processes of open- and closed-state inactivation predominate at different voltage ranges and feature distinct kinetics. How inactivation occurs over these different ranges to give rise to the complexity of NaV channel dynamics is unclear. Past functional studies and recent cryo-electron microscopy structures, however, reveal significant inactivation regulation from other NaV channel components. In this Hypothesis paper, we propose that the VSD of NaV repeat III (VSD-III), together with VSD-IV, orchestrates the inactivation-state occupancy of NaV channels by modulating the affinity of the intracellular binding site of the IFMT motif on the III-IV linker. We review and outline substantial evidence that VSD-III activates in two distinct steps, with the intermediate and fully activated conformation regulating closed- and open-state inactivation state occupancy by altering the formation and affinity of the IFMT crevice. A role of VSD-III in determining inactivation-state occupancy and recovery from inactivation suggests a regulatory mechanism for the state-dependent block by small-molecule anti-arrhythmic and anesthetic therapies.
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Affiliation(s)
- Paweorn Angsutararux
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO
| | - Po Wei Kang
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO
| | - Wandi Zhu
- Department of Medicine, Brigham and Women's Hospital, Boston, MA
| | - Jonathan R Silva
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO
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6
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Poulin H, Chahine M. R1617Q epilepsy mutation slows Na V 1.6 sodium channel inactivation and increases the persistent current and neuronal firing. J Physiol 2021; 599:1651-1664. [PMID: 33442870 DOI: 10.1113/jp280838] [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: 09/21/2020] [Accepted: 12/21/2020] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS A human NaV 1.6 construct was established to study the biophysical consequences of the R1617Q mutation on NaV 1.6 identified in patients with unclassified epileptic encephalopathy and severe intellectual disability. The R1617Q mutation disrupts the inactivation process of the channel, and more specifically, slows the current decay, increases the persistent sodium current that was blocked by tetrodotoxin and riluzole, and disrupts the inactivation voltage-dependence and increases the kinetics of recovery. In native hippocampal neurons, the R1617Q mutation exhibited a significant increase in action potentials triggered in response to stimulation and a significant increase in the number of neurons that exhibited spontaneous activity compared to neurons expressing WT channels that were inhibited by riluzole. The abnormally persistent current activity caused by the disruption of the channel inactivation process in NaV 1.6/R1617Q may result in epileptic encephalopathy in patients. ABSTRACT The voltage-gated sodium channel NaV 1.6 is the most abundantly expressed sodium channel isoform in the central nervous system. It plays a critical role in saltatory and continuous conduction. Although over 40 NaV 1.6 mutations have been linked to epileptic encephalopathy, only a few have been functionally analysed. In the present study, we characterized a NaV 1.6 mutation (R1617Q) identified in patients with epileptic encephalopathy and intellectual disability. R1617Q substitutes an arginine for a glutamine in the S4 segment of domain IV, which plays a major role in coupling the activation and inactivation of sodium channels. We used patch-clamp to show that R1617Q is a gain-of-function mutation. It is typified by slower inactivation kinetics and a loss of inactivation of voltage-dependence, which result in a 2.5-fold increase in the window current. In addition, sodium currents exhibited an enhanced rate of recovery from inactivation, most likely due to the destabilization of the inactivation state. The alterations in the fast inactivation caused a significant increase in the persistent sodium current. Overexpression of R1617Q in rat hippocampal neurons resulted in an increase in action potential firing activity that was inhibited by riluzole, consistent with the gain-of-function observed. We conclude that the R1617Q mutation causes neuronal hyperexcitability and may result in epileptic encephalopathy.
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Affiliation(s)
- Hugo Poulin
- CERVO Brain Research Centre, Quebec City, Québec, Canada
| | - Mohamed Chahine
- CERVO Brain Research Centre, Quebec City, Québec, Canada.,Department of Medicine, Faculty of Medicine, Université Laval, Quebec City, Québec, Canada
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7
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Nakajima T, Kaneko Y, Dharmawan T, Kurabayashi M. Role of the voltage sensor module in Na v domain IV on fast inactivation in sodium channelopathies: The implication of closed-state inactivation. Channels (Austin) 2020; 13:331-343. [PMID: 31357904 PMCID: PMC6713248 DOI: 10.1080/19336950.2019.1649521] [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] [Indexed: 12/19/2022] Open
Abstract
The segment 4 (S4) voltage sensor in voltage-gated sodium channels (Navs) have domain-specific functions, and the S4 segment in domain DIV (DIVS4) plays a key role in the activation and fast inactivation processes through the coupling of arginine residues in DIVS4 with residues of putative gating charge transfer center (pGCTC) in DIVS1-3. In addition, the first four arginine residues (R1-R4) in Nav DIVS4 have position-specific functions in the fast inactivation process, and mutations in these residues are associated with diverse phenotypes of Nav-related diseases (sodium channelopathies). R1 and R2 mutations commonly display a delayed fast inactivation, causing a gain-of-function, whereas R3 and R4 mutations commonly display a delayed recovery from inactivation and profound use-dependent current attenuation, causing a severe loss-of-function. In contrast, mutations of residues of pGCTC in Nav DIVS1-3 can also alter fast inactivation. Such alterations in fast inactivation may be caused by disrupted interactions of DIVS4 with DIVS1-3. Despite fast inactivation of Navs occurs from both the open-state (open-state inactivation; OSI) and closed state (closed-state inactivation; CSI), changes in CSI have received considerably less attention than those in OSI in the pathophysiology of sodium channelopathies. CSI can be altered by mutations of arginine residues in DIVS4 and residues of pGCTC in Navs, and altered CSI can be an underlying primary biophysical defect of sodium channelopathies. Therefore, CSI should receive focus in order to clarify the pathophysiology of sodium channelopathies.
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Affiliation(s)
- Tadashi Nakajima
- a Department of Cardiovascular Medicine, Gunma University Graduate School of Medicine , Maebashi , Gunma , Japan
| | - Yoshiaki Kaneko
- a Department of Cardiovascular Medicine, Gunma University Graduate School of Medicine , Maebashi , Gunma , Japan
| | - Tommy Dharmawan
- a Department of Cardiovascular Medicine, Gunma University Graduate School of Medicine , Maebashi , Gunma , Japan
| | - Masahiko Kurabayashi
- a Department of Cardiovascular Medicine, Gunma University Graduate School of Medicine , Maebashi , Gunma , Japan
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8
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Thull S, Neacsu C, O'Reilly AO, Bothe S, Hausmann R, Huth T, Meents J, Lampert A. Mechanism underlying hooked resurgent-like tail currents induced by an insecticide in human cardiac Nav1.5. Toxicol Appl Pharmacol 2020; 397:115010. [PMID: 32302602 DOI: 10.1016/j.taap.2020.115010] [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: 02/10/2020] [Revised: 04/12/2020] [Accepted: 04/14/2020] [Indexed: 01/02/2023]
Abstract
Voltage-gated sodium channels are responsible not only for the fast upstroke of the action potential, but they also modify cellular excitability via persistent and resurgent currents. Insecticides act via permanently opening sodium channels to immobilize the animals. Cellular recordings performed decades ago revealed distinctly hooked tail currents induced by these compounds. Here, we applied the classical type-II pyrethroid deltamethrin on human cardiac Nav1.5 and observed resurgent-like currents at very negative potentials in the absence of any pore-blocker, which resemble those hooked tail currents. We show that deltamethrin dramatically slows both fast inactivation and deactivation of Nav1.5 and thereby induces large persistent currents. Using the sea anemone toxin ATx-II as a tool to prevent all inactivation-related processes, resurgent-like currents were eliminated while persistent currents were preserved. Our experiments suggest that, in deltamethrin-modified channels, recovery from inactivation occurs faster than delayed deactivation, opening a brief window for sodium influx and leading to hooked, resurgent-like currents, in the absence of an open channel blocker. Thus, we now explain with pharmacological methods the biophysical gating changes underlying the deltamethrin induced hooked tail currents. SUMMARY: The pyrethroid deltamethrin induces hooked resurgent-like tail currents in human cardiac voltage-gated Nav1.5 channels. Using deltamethrin and ATx-II, we identify additional conducting channel states caused by a faster recovery from inactivation compared to the deltamethrin-induced delayed deactivation.
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Affiliation(s)
- Sarah Thull
- Institute of Physiology, RWTH Aachen University, Pauwelsstr. 30, 52074 Aachen, Germany
| | - Cristian Neacsu
- Institut für Physiologie und Pathophysiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Universitaetsstr. 17, 91054 Erlangen, Germany
| | - Andrias O O'Reilly
- School of Natural Sciences and Psychology, Liverpool John Moores University, Liverpool, UK
| | - Stefanie Bothe
- Institute of Physiology, RWTH Aachen University, Pauwelsstr. 30, 52074 Aachen, Germany; Research Training Group 2416 MultiSenses-MultiScales, RWTH Aachen University, Aachen, Germany
| | - Ralf Hausmann
- Institute of Clinical Pharmacology, RWTH Aachen University, Wendlingweg 2, 52074 Aachen, Germany
| | - Tobias Huth
- Institut für Physiologie und Pathophysiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Universitaetsstr. 17, 91054 Erlangen, Germany
| | - Jannis Meents
- Institute of Physiology, RWTH Aachen University, Pauwelsstr. 30, 52074 Aachen, Germany.
| | - Angelika Lampert
- Institute of Physiology, RWTH Aachen University, Pauwelsstr. 30, 52074 Aachen, Germany; Research Training Group 2416 MultiSenses-MultiScales, RWTH Aachen University, Aachen, Germany; Research Training Group 2415 ME3T, RWTH Aachen University, Aachen, Germany.
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9
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Morales F, Pusch M. An Up-to-Date Overview of the Complexity of Genotype-Phenotype Relationships in Myotonic Channelopathies. Front Neurol 2020; 10:1404. [PMID: 32010054 PMCID: PMC6978732 DOI: 10.3389/fneur.2019.01404] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Accepted: 12/23/2019] [Indexed: 12/11/2022] Open
Abstract
Myotonic disorders are inherited neuromuscular diseases divided into dystrophic myotonias and non-dystrophic myotonias (NDM). The latter is a group of dominant or recessive diseases caused by mutations in genes encoding ion channels that participate in the generation and control of the skeletal muscle action potential. Their altered function causes hyperexcitability of the muscle membrane, thereby triggering myotonia, the main sign in NDM. Mutations in the genes encoding voltage-gated Cl− and Na+ channels (respectively, CLCN1 and SCN4A) produce a wide spectrum of phenotypes, which differ in age of onset, affected muscles, severity of myotonia, degree of hypertrophy, and muscle weakness, disease progression, among others. More than 200 CLCN1 and 65 SCN4A mutations have been identified and described, but just about half of them have been functionally characterized, an approach that is likely extremely helpful to contribute to improving the so-far rather poor clinical correlations present in NDM. The observed poor correlations may be due to: (1) the wide spectrum of symptoms and overlapping phenotypes present in both groups (Cl− and Na+ myotonic channelopathies) and (2) both genes present high genotypic variability. On the one hand, several mutations cause a unique and reproducible phenotype in most patients. On the other hand, some mutations can have different inheritance pattern and clinical phenotypes in different families. Conversely, different mutations can be translated into very similar phenotypes. For these reasons, the genotype-phenotype relationships in myotonic channelopathies are considered complex. Although the molecular bases for the clinical variability present in myotonic channelopathies remain obscure, several hypotheses have been put forward to explain the variability, which include: (a) differential allelic expression; (b) trans-acting genetic modifiers; (c) epigenetic, hormonal, or environmental factors; and (d) dominance with low penetrance. Improvements in clinical tests, the recognition of the different phenotypes that result from particular mutations and the understanding of how a mutation affects the structure and function of the ion channel, together with genetic screening, is expected to improve clinical correlation in NDMs.
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Affiliation(s)
- Fernando Morales
- Instituto de Investigaciones en Salud, Universidad de Costa, San José, Costa Rica
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10
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Glazer AM, Kroncke BM, Matreyek KA, Yang T, Wada Y, Shields T, Salem JE, Fowler DM, Roden DM. Deep Mutational Scan of an SCN5A Voltage Sensor. CIRCULATION-GENOMIC AND PRECISION MEDICINE 2020; 13:e002786. [PMID: 31928070 DOI: 10.1161/circgen.119.002786] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
BACKGROUND Variants in ion channel genes have classically been studied in low throughput by patch clamping. Deep mutational scanning is a complementary approach that can simultaneously assess function of thousands of variants. METHODS We have developed and validated a method to perform a deep mutational scan of variants in SCN5A, which encodes the major voltage-gated sodium channel in the heart. We created a library of nearly all possible variants in a 36 base region of SCN5A in the S4 voltage sensor of domain IV and stably integrated the library into HEK293T cells. RESULTS In preliminary experiments, challenge with 3 drugs (veratridine, brevetoxin, and ouabain) could discriminate wild-type channels from gain- and loss-of-function pathogenic variants. High-throughput sequencing of the pre- and postdrug challenge pools was used to count the prevalence of each variant and identify variants with abnormal function. The deep mutational scan scores identified 40 putative gain-of-function and 33 putative loss-of-function variants. For 8 of 9 variants, patch clamping data were consistent with the scores. CONCLUSIONS These experiments demonstrate the accuracy of a high-throughput in vitro scan of SCN5A variant function, which can be used to identify deleterious variants in SCN5A and other ion channel genes.
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Affiliation(s)
- Andrew M Glazer
- Department of Medicine, Division of Clinical Pharmacology, Vanderbilt Center for Arrhythmia Research and Therapeutics (A.M.G., B.M.K., T.Y., Y.W., T.S., J.-E.S., D.M.R.), Vanderbilt University Medical Center, Nashville, TN
| | - Brett M Kroncke
- Department of Medicine, Division of Clinical Pharmacology, Vanderbilt Center for Arrhythmia Research and Therapeutics (A.M.G., B.M.K., T.Y., Y.W., T.S., J.-E.S., D.M.R.), Vanderbilt University Medical Center, Nashville, TN
| | - Kenneth A Matreyek
- Department of Genome Sciences, University of Washington, Seattle (K.A.M., D.M.F.)
| | - Tao Yang
- Department of Medicine, Division of Clinical Pharmacology, Vanderbilt Center for Arrhythmia Research and Therapeutics (A.M.G., B.M.K., T.Y., Y.W., T.S., J.-E.S., D.M.R.), Vanderbilt University Medical Center, Nashville, TN
| | - Yuko Wada
- Department of Medicine, Division of Clinical Pharmacology, Vanderbilt Center for Arrhythmia Research and Therapeutics (A.M.G., B.M.K., T.Y., Y.W., T.S., J.-E.S., D.M.R.), Vanderbilt University Medical Center, Nashville, TN
| | - Tiffany Shields
- Department of Medicine, Division of Clinical Pharmacology, Vanderbilt Center for Arrhythmia Research and Therapeutics (A.M.G., B.M.K., T.Y., Y.W., T.S., J.-E.S., D.M.R.), Vanderbilt University Medical Center, Nashville, TN
| | - Joe-Elie Salem
- Department of Medicine, Division of Clinical Pharmacology, Vanderbilt Center for Arrhythmia Research and Therapeutics (A.M.G., B.M.K., T.Y., Y.W., T.S., J.-E.S., D.M.R.), Vanderbilt University Medical Center, Nashville, TN.,Department of Clinical Pharmacology, APHP, Sorbonne Université, INSERM, CIC-1421, Hôpital Pitié-Salpêtrière, Paris, France (J.-E.S.)
| | - Douglas M Fowler
- Department of Genome Sciences, University of Washington, Seattle (K.A.M., D.M.F.)
| | - Dan M Roden
- Department of Medicine, Division of Clinical Pharmacology, Vanderbilt Center for Arrhythmia Research and Therapeutics (A.M.G., B.M.K., T.Y., Y.W., T.S., J.-E.S., D.M.R.), Vanderbilt University Medical Center, Nashville, TN.,Department of Biomedical Informatics (D.M.R.), Vanderbilt University Medical Center, Nashville, TN.,Department of Pharmacology (D.M.R.), Vanderbilt University Medical Center, Nashville, TN
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11
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Kokunai Y, Dalle C, Vicart S, Sternberg D, Pouliot V, Bendahhou S, Fournier E, Chahine M, Fontaine B, Nicole S. A204E mutation in Na v1.4 DIS3 exerts gain- and loss-of-function effects that lead to periodic paralysis combining hyper- with hypo-kalaemic signs. Sci Rep 2018; 8:16681. [PMID: 30420713 PMCID: PMC6232142 DOI: 10.1038/s41598-018-34750-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Accepted: 10/25/2018] [Indexed: 12/11/2022] Open
Abstract
Periodic paralyses (PP) are characterized by episodic muscle weakness and are classified into the distinct hyperkalaemic (hyperPP) and hypokalaemic (hypoPP) forms. The dominantly-inherited form of hyperPP is caused by overactivity of Nav1.4 - the skeletal muscle voltage-gated sodium channel. Familial hypoPP results from a leaking gating pore current induced by dominant mutations in Nav1.4 or Cav1.1, the skeletal muscle voltage-gated calcium channel. Here, we report an individual with clinical signs of hyperPP and hypokalaemic episodes of muscle paralysis who was heterozygous for the novel p.Ala204Glu (A204E) substitution located in one region of Nav1.4 poor in disease-related variations. A204E induced a significant decrease of sodium current density, increased the window current, enhanced fast and slow inactivation of Nav1.4, and did not cause gating pore current in functional analyses. Interestingly, the negative impact of A204E on Nav1.4 activation was strengthened in low concentration of extracellular K+. Our data prove the existence of a phenotype combining signs of hyperPP and hypoPP due to dominant Nav1.4 mutations. The hyperPP component would result from gain-of-function effects on Nav1.4 and the hypokalemic episodes of paralysis from loss-of-function effects strengthened by low K+. Our data argue for a non-negligible role of Nav1.4 loss-of-function in familial hypoPP.
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Affiliation(s)
- Yosuke Kokunai
- Inserm U1127, CNRS UMR 7225, Sorbonne Universités, UPMC Univ Paris 06 UMR S 1127, Institut du Cerveau et de la Moelle épinière (ICM), F-75013, Paris, France
| | - Carine Dalle
- Inserm U1127, CNRS UMR 7225, Sorbonne Universités, UPMC Univ Paris 06 UMR S 1127, Institut du Cerveau et de la Moelle épinière (ICM), F-75013, Paris, France
| | - Savine Vicart
- Inserm U1127, CNRS UMR 7225, Sorbonne Universités, UPMC Univ Paris 06 UMR S 1127, Institut du Cerveau et de la Moelle épinière (ICM), F-75013, Paris, France
- AP-HP, Hôpital Universitaire Pitié-Salpétrière, National Reference Center for Channelopathies, F-75013, Paris, France
| | - Damien Sternberg
- Inserm U1127, CNRS UMR 7225, Sorbonne Universités, UPMC Univ Paris 06 UMR S 1127, Institut du Cerveau et de la Moelle épinière (ICM), F-75013, Paris, France
- AP-HP, Hôpital Universitaire Pitié-Salpétrière, National Reference Center for Channelopathies, F-75013, Paris, France
| | - Valérie Pouliot
- Centre de recherche CERVO, Institut Universitaire en Santé Mentale de Québec, Quebec City, QC, G1J 2G3, Canada
- Department of Medicine, Université Laval, Quebec City, QC, G1K 7P4, Canada
| | - Said Bendahhou
- CNRS UMR7370, LP2M, Labex ICST, University Nice Sophia-Antipolis, Faculté de Médecine, Nice, France
| | - Emmanuel Fournier
- Inserm U1127, CNRS UMR 7225, Sorbonne Universités, UPMC Univ Paris 06 UMR S 1127, Institut du Cerveau et de la Moelle épinière (ICM), F-75013, Paris, France
- AP-HP, Hôpital Universitaire Pitié-Salpétrière, National Reference Center for Channelopathies, F-75013, Paris, France
| | - Mohamed Chahine
- Centre de recherche CERVO, Institut Universitaire en Santé Mentale de Québec, Quebec City, QC, G1J 2G3, Canada
- Department of Medicine, Université Laval, Quebec City, QC, G1K 7P4, Canada
| | - Bertrand Fontaine
- Inserm U1127, CNRS UMR 7225, Sorbonne Universités, UPMC Univ Paris 06 UMR S 1127, Institut du Cerveau et de la Moelle épinière (ICM), F-75013, Paris, France.
- AP-HP, Hôpital Universitaire Pitié-Salpétrière, National Reference Center for Channelopathies, F-75013, Paris, France.
| | - Sophie Nicole
- Inserm U1127, CNRS UMR 7225, Sorbonne Universités, UPMC Univ Paris 06 UMR S 1127, Institut du Cerveau et de la Moelle épinière (ICM), F-75013, Paris, France.
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12
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Bayless-Edwards L, Winston V, Lehmann-Horn F, Arinze P, Groome JR, Jurkat-Rott K. Na V1.4 DI-S4 periodic paralysis mutation R222W enhances inactivation and promotes leak current to attenuate action potentials and depolarize muscle fibers. Sci Rep 2018; 8:10372. [PMID: 29991727 PMCID: PMC6039468 DOI: 10.1038/s41598-018-28594-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Accepted: 06/20/2018] [Indexed: 01/24/2023] Open
Abstract
Hypokalemic periodic paralysis is a skeletal muscle disease characterized by episodic weakness associated with low serum potassium. We compared clinical and biophysical effects of R222W, the first hNaV1.4 domain I mutation linked to this disease. R222W patients exhibited a higher density of fibers with depolarized resting membrane potentials and produced action potentials that were attenuated compared to controls. Functional characterization of the R222W mutation in heterologous expression included the inactivation deficient IFM/QQQ background to isolate activation. R222W decreased sodium current and slowed activation without affecting probability. Consistent with the phenotype of muscle weakness, R222W shifted fast inactivation to hyperpolarized potentials, promoted more rapid entry, and slowed recovery. R222W increased the extent of slow inactivation and slowed its recovery. A two-compartment skeletal muscle fiber model revealed that defects in fast inactivation sufficiently explain action potential attenuation in patients. Molecular dynamics simulations showed that R222W disrupted electrostatic interactions within the gating pore, supporting the observation that R222W promotes omega current at hyperpolarized potentials. Sodium channel inactivation defects produced by R222W are the primary driver of skeletal muscle fiber action potential attenuation, while hyperpolarization-induced omega current produced by that mutation promotes muscle fiber depolarization.
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Affiliation(s)
| | - Vern Winston
- Department of Biological Sciences, Idaho State University, 83209, Pocatello, ID, USA
| | | | - Paula Arinze
- Department of Biological Sciences, Idaho State University, 83209, Pocatello, ID, USA
| | - James R Groome
- Department of Biological Sciences, Idaho State University, 83209, Pocatello, ID, USA.
| | - Karin Jurkat-Rott
- Department of Neuroanesthesiology, Clinic for Neurosurgery, Ulm University, Guenzburg, Germany
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13
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Substitutions of the S4DIV R2 residue (R1451) in Na V1.4 lead to complex forms of paramyotonia congenita and periodic paralyses. Sci Rep 2018; 8:2041. [PMID: 29391559 PMCID: PMC5794747 DOI: 10.1038/s41598-018-20468-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Accepted: 01/18/2018] [Indexed: 01/19/2023] Open
Abstract
Mutations in NaV1.4, the skeletal muscle voltage-gated Na+ channel, underlie several skeletal muscle channelopathies. We report here the functional characterization of two substitutions targeting the R1451 residue and resulting in 3 distinct clinical phenotypes. The R1451L is a novel pathogenic substitution found in two unrelated individuals. The first individual was diagnosed with non-dystrophic myotonia, whereas the second suffered from an unusual phenotype combining hyperkalemic and hypokalemic episodes of periodic paralysis (PP). The R1451C substitution was found in one individual with a single attack of hypoPP induced by glucocorticoids. To elucidate the biophysical mechanism underlying the phenotypes, we used the patch-clamp technique to study tsA201 cells expressing WT or R1451C/L channels. Our results showed that both substitutions shifted the inactivation to hyperpolarized potentials, slowed the kinetics of inactivation, slowed the recovery from slow inactivation and reduced the current density. Cooling further enhanced these abnormalities. Homology modeling revealed a disruption of hydrogen bonds in the voltage sensor domain caused by R1451C/L. We concluded that the altered biophysical properties of R1451C/L well account for the PMC-hyperPP cluster and that additional factors likely play a critical role in the inter-individual differences of clinical expression resulting from R1451C/L.
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14
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Distinct modulation of inactivation by a residue in the pore domain of voltage-gated Na + channels: mechanistic insights from recent crystal structures. Sci Rep 2018; 8:631. [PMID: 29330525 PMCID: PMC5766632 DOI: 10.1038/s41598-017-18919-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Accepted: 12/18/2017] [Indexed: 12/19/2022] Open
Abstract
Inactivation of voltage-gated Na+ channels (VGSC) is essential for the regulation of cellular excitability. The molecular rearrangement underlying inactivation is thought to involve the intracellular linker between domains III and IV serving as inactivation lid, the receptor for the lid (domain III S4-S5 linker) and the pore-lining S6 segements. To better understand the role of the domain IV S6 segment in inactivation we performed a cysteine scanning mutagenesis of this region in rNav 1.4 channels and screened the constructs for perturbations in the voltage-dependence of steady state inactivation. This screen was performed in the background of wild-type channels and in channels carrying the mutation K1237E, which profoundly alters both permeation and gating-properties. Of all tested constructs the mutation I1581C was unique in that the mutation-induced gating changes were strongly influenced by the mutational background. This suggests that I1581 is involved in specific short-range interactions during inactivation. In recently published crystal structures VGSCs the respective amino acids homologous to I1581 appear to control a bend of the S6 segment which is critical to the gating process. Furthermore, I1581 may be involved in the transmission of the movement of the DIII voltage-sensor to the domain IV S6 segment.
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15
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Abstract
Voltage-gated sodium (Na+) channels are expressed in virtually all electrically excitable tissues and are essential for muscle contraction and the conduction of impulses within the peripheral and central nervous systems. Genetic disorders that disrupt the function of these channels produce an array of Na+ channelopathies resulting in neuronal impairment, chronic pain, neuromuscular pathologies, and cardiac arrhythmias. Because of their importance to the conduction of electrical signals, Na+ channels are the target of a wide variety of local anesthetic, antiarrhythmic, anticonvulsant, and antidepressant drugs. The voltage-gated family of Na+ channels is composed of α-subunits that encode for the voltage sensor domains and the Na+-selective permeation pore. In vivo, Na+ channel α-subunits are associated with one or more accessory β-subunits (β1-β4) that regulate gating properties, trafficking, and cell-surface expression of the channels. The permeation pore of Na+ channels is divided in two parts: the outer mouth of the pore is the site of the ion selectivity filter, while the inner cytoplasmic pore serves as the channel activation gate. The cytoplasmic lining of the permeation pore is formed by the S6 segments that include highly conserved aromatic amino acids important for drug binding. These residues are believed to undergo voltage-dependent conformational changes that alter drug binding as the channels cycle through the closed, open, and inactivated states. The purpose of this chapter is to broadly review the mechanisms of Na+ channel gating and the models used to describe drug binding and Na+ channel inhibition.
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Affiliation(s)
- M E O'Leary
- Cooper Medical School of Rowan University, Camden, NJ, USA
| | - M Chahine
- CERVO Brain Research Center, Institut universitaire en santé mentale de Québec, Quebec City, QC, Canada.
- Department of Medicine, Université Laval, Quebec City, QC, Canada.
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16
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Ke Q, Ye J, Tang S, Wang J, Luo B, Ji F, Zhang X, Yu Y, Cheng X, Li Y. N1366S mutation of human skeletal muscle sodium channel causes paramyotonia congenita. J Physiol 2017; 595:6837-6850. [PMID: 28940424 DOI: 10.1113/jp274877] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Accepted: 09/15/2017] [Indexed: 12/16/2022] Open
Abstract
KEY POINTS Paramyotonia congenita is a hereditary channelopathy caused by missense mutations in the SCN4A gene, which encodes the α subunit of the human skeletal muscle voltage-gated sodium channel NaV1.4. Affected individuals suffered from myotonia and paralysis of muscles, which were aggravated by exposure to cold. We report a three-generation Chinese family with patients presenting paramyotonia congenita and identify a novel N1366S mutation of NaV1.4. Whole-cell electrophysiological recordings of the N1366S channel reveal a gain-of-function change of gating in response to cold. Modelling and molecular dynamic simulation data suggest that an arginine-to-serine substitution at position 1366 increases the distance from N1366 to R1454 and disrupts the hydrogen bond formed between them at low temperature. We demonstrate that N1366S is a disease-causing mutation and that the temperature-sensitive alteration of N1366S channel activity may be responsible for the pronounced paramyotonia congenita symptoms of these patients. ABSTRACT Paramyotonia congenita is an autosomal dominant skeletal muscle channelopathy caused by missense mutations in SCN4A, the gene encoding the α subunit of the human skeletal muscle voltage-gated sodium channel NaV1.4. We report a three-generation family in which six members present clinical symptoms of paramyotonia congenita characterized by a marked worsening of myotonia by cold and by the presence of clear episodes of paralysis. We identified a novel mutation in SCN4A (Asn1366Ser, N1366S) in all patients in the family but not in healthy relatives or in 500 normal control subjects. Functional analysis of the channel protein expressed in HEK293 cells by whole-cell patch clamp recording revealed that the N1366S mutation led to significant alterations in the gating process of the NaV1.4 channel. The N1366S mutant displayed a cold-induced hyperpolarizing shift in the voltage dependence of activation and a depolarizing shift in fast inactivation, as well as a reduced rate of fast inactivation and accelerated recovery from fast inactivation. In addition, homology modelling and molecular dynamic simulation of N1366S and wild-type NaV1.4 channels indicated that the arginine-to-serine substitution disrupted the hydrogen bond formed between N1366 and R1454. Together, our results suggest that N1366S is a gain-of-function mutation of NaV1.4 at low temperature and the mutation may be responsible for the clinical symptoms of paramyotonia congenita in the affected family and constitute a basis for studies into its pathogenesis.
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Affiliation(s)
- Qing Ke
- Department of Neurology, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Jia Ye
- Department of Physiology, Institute of Neuroscience, Key Laboratory of Medical Neurobiology of Ministry of Health of China, Zhejiang Province Key Laboratory of Tissue Engineering and Regenerative Medicine, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Siyang Tang
- Department of Physiology, Institute of Neuroscience, Key Laboratory of Medical Neurobiology of Ministry of Health of China, Zhejiang Province Key Laboratory of Tissue Engineering and Regenerative Medicine, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Jin Wang
- Institute of Medical Sciences and Department of Pharmacology, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Benyan Luo
- Department of Neurology, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Fang Ji
- Department of Neurology, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Xu Zhang
- Bejing Epigen Medical Institute, Beijing, China
| | - Ye Yu
- Institute of Medical Sciences and Department of Pharmacology, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Xiaoyang Cheng
- Department of Anatomy, Histology and Embryology, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yuezhou Li
- Department of Physiology, Institute of Neuroscience, Key Laboratory of Medical Neurobiology of Ministry of Health of China, Zhejiang Province Key Laboratory of Tissue Engineering and Regenerative Medicine, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
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17
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Lowrie M, Garosi L. Classification of Involuntary Movements in Dogs: Myoclonus and Myotonia. J Vet Intern Med 2017; 31:979-987. [PMID: 28557061 PMCID: PMC5508344 DOI: 10.1111/jvim.14771] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Revised: 04/07/2017] [Accepted: 04/27/2017] [Indexed: 12/25/2022] Open
Abstract
Myoclonus is a sudden brief, involuntary muscle jerk. Of all the movement disorders, myoclonus is the most difficult to encapsulate into any simple framework. On the one hand, a classification system is required that is clinically useful to aid in guiding diagnosis and treatment. On the other hand, there is need for a system that organizes current knowledge regarding biological mechanisms to guide scientific research. These 2 needs are distinct, making it challenging to develop a robust classification system suitable for all purposes. We attempt to classify myoclonus as “epileptic” and “nonepileptic” based on its association with epileptic seizures. Myotonia in people may be divided into 2 clinically and molecularly defined forms: (1) nondystrophic myotonias and (2) myotonic dystrophies. The former are a group of skeletal muscle channelopathies characterized by delayed skeletal muscle relaxation. Many distinct clinical phenotypes are recognized in people, the majority relating to mutations in skeletal muscle voltage‐gated chloride (CLCN1) and sodium channel (SCN4A) genes. In dogs, myotonia is associated with mutations in CLCN1. The myotonic dystrophies are considered a multisystem clinical syndrome in people encompassing 2 clinically and molecularly defined forms designated myotonic dystrophy types 1 and 2. No mutation has been linked to veterinary muscular dystrophies. We detail veterinary examples of myotonia and attempt classification according to guidelines used in humans. This more precise categorization of myoclonus and myotonia aims to promote the search for molecular markers contributing to the phenotypic spectrum of disease. Our work aimed to assist recognition for these 2 enigmatic conditions.
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Affiliation(s)
- M Lowrie
- Dovecote Veterinary Hospital, Derby, UK
| | - L Garosi
- Davies Veterinary Specialists, Hitchin, UK
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18
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Palmio J, Sandell S, Hanna MG, Männikkö R, Penttilä S, Udd B. Predominantly myalgic phenotype caused by the c.3466G>A p.A1156T mutation in SCN4A gene. Neurology 2017; 88:1520-1527. [PMID: 28330959 PMCID: PMC5395072 DOI: 10.1212/wnl.0000000000003846] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2016] [Accepted: 01/20/2017] [Indexed: 12/27/2022] Open
Abstract
Objective: To characterize the clinical phenotype in patients with p.A1156T sodium channel mutation. Methods: Twenty-nine Finnish patients identified with the c.3466G>A p.A1156T mutation in the SCN4A gene were extensively examined. In a subsequent study, 63 patients with similar myalgic phenotype and with negative results in myotonic dystrophy type 2 genetic screening (DM2-neg group) and 93 patients diagnosed with fibromyalgia were screened for the mutation. Functional consequences of the p.A1156T mutation were studied in HEK293 cells with whole-cell patch clamp. Results: The main clinical manifestation in p.A1156T patients was not myotonia or periodic paralysis but exercise- and cold-induced muscle cramps, muscle stiffness, and myalgia. EMG myotonic discharges were detected in most but not all. Electrophysiologic compound muscle action potentials exercise test showed variable results. The p.A1156T mutation was identified in one patient in the DM2-neg group but not in the fibromyalgia group, making a total of 30 patients so far identified. Functional studies of the p.A1156T mutation showed mild attenuation of channel fast inactivation. Conclusions: The unspecific symptoms of myalgia stiffness and exercise intolerance without clinical myotonia or periodic paralysis in p.A1156T patients make the diagnosis challenging. The symptoms of milder SCN4A mutations may be confused with other similar myalgic syndromes, including fibromyalgia and myotonic dystrophy type 2.
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Affiliation(s)
- Johanna Palmio
- From the Neuromuscular Research Center (J.P., S.P., B.U.), Department of Neurology, Tampere University and University Hospital, Neurology; Seinäjoki Central Hospital (S.S.), Department of Neurology, Finland; MRC Centre for Neuromuscular Disease (M.G.H., R.M.), UCL Institute of Neurology, Queen Square, London, UK; Folkhälsan Institute of Genetics and the Department of Medical Genetics (B.U.), Haartman Institute, University of Helsinki; and Vaasa Central Hospital (B.U.), Department of Neurology, Finland.
| | - Satu Sandell
- From the Neuromuscular Research Center (J.P., S.P., B.U.), Department of Neurology, Tampere University and University Hospital, Neurology; Seinäjoki Central Hospital (S.S.), Department of Neurology, Finland; MRC Centre for Neuromuscular Disease (M.G.H., R.M.), UCL Institute of Neurology, Queen Square, London, UK; Folkhälsan Institute of Genetics and the Department of Medical Genetics (B.U.), Haartman Institute, University of Helsinki; and Vaasa Central Hospital (B.U.), Department of Neurology, Finland
| | - Michael G Hanna
- From the Neuromuscular Research Center (J.P., S.P., B.U.), Department of Neurology, Tampere University and University Hospital, Neurology; Seinäjoki Central Hospital (S.S.), Department of Neurology, Finland; MRC Centre for Neuromuscular Disease (M.G.H., R.M.), UCL Institute of Neurology, Queen Square, London, UK; Folkhälsan Institute of Genetics and the Department of Medical Genetics (B.U.), Haartman Institute, University of Helsinki; and Vaasa Central Hospital (B.U.), Department of Neurology, Finland
| | - Roope Männikkö
- From the Neuromuscular Research Center (J.P., S.P., B.U.), Department of Neurology, Tampere University and University Hospital, Neurology; Seinäjoki Central Hospital (S.S.), Department of Neurology, Finland; MRC Centre for Neuromuscular Disease (M.G.H., R.M.), UCL Institute of Neurology, Queen Square, London, UK; Folkhälsan Institute of Genetics and the Department of Medical Genetics (B.U.), Haartman Institute, University of Helsinki; and Vaasa Central Hospital (B.U.), Department of Neurology, Finland
| | - Sini Penttilä
- From the Neuromuscular Research Center (J.P., S.P., B.U.), Department of Neurology, Tampere University and University Hospital, Neurology; Seinäjoki Central Hospital (S.S.), Department of Neurology, Finland; MRC Centre for Neuromuscular Disease (M.G.H., R.M.), UCL Institute of Neurology, Queen Square, London, UK; Folkhälsan Institute of Genetics and the Department of Medical Genetics (B.U.), Haartman Institute, University of Helsinki; and Vaasa Central Hospital (B.U.), Department of Neurology, Finland
| | - Bjarne Udd
- From the Neuromuscular Research Center (J.P., S.P., B.U.), Department of Neurology, Tampere University and University Hospital, Neurology; Seinäjoki Central Hospital (S.S.), Department of Neurology, Finland; MRC Centre for Neuromuscular Disease (M.G.H., R.M.), UCL Institute of Neurology, Queen Square, London, UK; Folkhälsan Institute of Genetics and the Department of Medical Genetics (B.U.), Haartman Institute, University of Helsinki; and Vaasa Central Hospital (B.U.), Department of Neurology, Finland
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19
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Yan H, Wang C, Marx SO, Pitt GS. Calmodulin limits pathogenic Na+ channel persistent current. J Gen Physiol 2017; 149:277-293. [PMID: 28087622 PMCID: PMC5299624 DOI: 10.1085/jgp.201611721] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2016] [Revised: 12/13/2016] [Accepted: 12/19/2016] [Indexed: 01/29/2023] Open
Abstract
The molecular mechanisms controlling “persistent” current through voltage-gated Na+ channels are poorly understood. Yan et al. show that apocalmodulin binding to the intracellular C-terminal domain limits persistent Na+ flux and accelerates inactivation across the voltage-gated Na+ channel family. Increased “persistent” current, caused by delayed inactivation, through voltage-gated Na+ (NaV) channels leads to cardiac arrhythmias or epilepsy. The underlying molecular contributors to these inactivation defects are poorly understood. Here, we show that calmodulin (CaM) binding to multiple sites within NaV channel intracellular C-terminal domains (CTDs) limits persistent Na+ current and accelerates inactivation across the NaV family. Arrhythmia or epilepsy mutations located in NaV1.5 or NaV1.2 channel CTDs, respectively, reduce CaM binding either directly or by interfering with CTD–CTD interchannel interactions. Boosting the availability of CaM, thus shifting its binding equilibrium, restores wild-type (WT)–like inactivation in mutant NaV1.5 and NaV1.2 channels and likewise diminishes the comparatively large persistent Na+ current through WT NaV1.6, whose CTD displays relatively low CaM affinity. In cerebellar Purkinje neurons, in which NaV1.6 promotes a large physiological persistent Na+ current, increased CaM diminishes the persistent Na+ current, suggesting that the endogenous, comparatively weak affinity of NaV1.6 for apoCaM is important for physiological persistent current.
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Affiliation(s)
- Haidun Yan
- Ion Channel Research Unit, Duke University Medical Center, Durham, NC 27710
| | - Chaojian Wang
- Ion Channel Research Unit, Duke University Medical Center, Durham, NC 27710
| | - Steven O Marx
- Division of Cardiology, Department of Medicine, College of Physicians and Surgeons, Columbia University, New York, NY 10032.,Department of Pharmacology, College of Physicians and Surgeons, Columbia University, New York, NY 10032
| | - Geoffrey S Pitt
- Ion Channel Research Unit, Duke University Medical Center, Durham, NC 27710
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20
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Vaccaro SR. Derivation of Hodgkin-Huxley equations for a Na^{+} channel from a master equation for coupled activation and inactivation. Phys Rev E 2016; 94:052407. [PMID: 27967064 DOI: 10.1103/physreve.94.052407] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2016] [Indexed: 11/07/2022]
Abstract
The Na^{+} current in nerve and muscle membranes may be described in terms of the activation variable m(t) and the inactivation variable h(t), which are dependent on the transitions of S4 sensors of each of the Na^{+} channel domains DI to DIV. The time-dependence of the Na^{+} current and the rate equations satisfied by m(t) and h(t) may be derived from the solution to a master equation that describes the coupling between two or three activation sensors regulating the Na^{+} channel conductance and a two-stage inactivation process. If the inactivation rate from the closed or open states increases as the S4 sensors activate, a more general form of the Hodgkin-Huxley expression for the open-state probability may be derived where m(t) is dependent on both activation and inactivation processes. The voltage dependence of the rate functions for inactivation and recovery from inactivation are consistent with the empirically determined expressions and exhibit saturation for both depolarized and hyperpolarized clamp potentials.
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Affiliation(s)
- S R Vaccaro
- Department of Physics, University of Adelaide, Adelaide, South Australia, 5005, Australia
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21
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Bednarz M, Stunnenberg BC, Kusters B, Kamsteeg EJ, Saris CG, Groome J, Winston V, Meola G, Jurkat-Rott K, Voermans NC. A novel Ile1455Thr variant in the skeletal muscle sodium channel alpha-subunit in a patient with a severe adult-onset proximal myopathy with electrical myotonia and a patient with mild paramyotonia phenotype. Neuromuscul Disord 2016; 27:175-182. [PMID: 28024841 DOI: 10.1016/j.nmd.2016.09.023] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Revised: 09/04/2016] [Accepted: 09/28/2016] [Indexed: 12/19/2022]
Abstract
In sodium channelopathies, a severe fixed myopathy caused by a dominant mutation is rare. We describe two unrelated patients with a novel variant, p.Ile1455Thr, with phenotypes of paramyotonia in one case and fixed proximal myopathy with latent myotonia in another. In-vitro whole cell patch-clamp studies show that the mutation slows inactivation and accelerates recovery, in line with other paramyotonia variants with destabilized fast inactivation as pathomechanism. Additionally, p.IleI1455 causes a loss-of-function by reduced membrane insertion, right-shift of activation, and slowed kinetics. Molecular dynamics simulations comparing wild type and mutant Nav1.4 showed that threonine substitution hindered D4S4 mobility in response to membrane depolarization, consistent with effects of the mutation on channel inactivation. The fixed myopathy is likely to be associated to gain-of-function leading to sodium accumulation, regional edema, T-tubular swelling and mitochondrial stress. A possible contribution of the loss-of-function features towards myotonia and myopathy is discussed.
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Affiliation(s)
- Marcin Bednarz
- Division of Neurophysiology, Ulm University, Ulm, Germany
| | - Bas C Stunnenberg
- Department of Neurology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Benno Kusters
- Department of Pathology, Radboud University Medical Center, Nijmegen, The Netherlands; Department of Pathology, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Erik-Jan Kamsteeg
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Christiaan G Saris
- Department of Neurology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - James Groome
- Department of Biological Sciences, Idaho State University, Pocatello, ID 83209, USA
| | - Vern Winston
- Department of Biological Sciences, Idaho State University, Pocatello, ID 83209, USA
| | - Giovanni Meola
- Department of Biomedical Sciences for Health, University of Milan, IRCCS Policlinico San Donato, Italy
| | | | - Nicol C Voermans
- Department of Neurology, Radboud University Medical Center, Nijmegen, The Netherlands.
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22
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Ahern CA, Payandeh J, Bosmans F, Chanda B. The hitchhiker's guide to the voltage-gated sodium channel galaxy. ACTA ACUST UNITED AC 2016; 147:1-24. [PMID: 26712848 PMCID: PMC4692491 DOI: 10.1085/jgp.201511492] [Citation(s) in RCA: 217] [Impact Index Per Article: 27.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Eukaryotic voltage-gated sodium (Nav) channels contribute to the rising phase of action potentials and served as an early muse for biophysicists laying the foundation for our current understanding of electrical signaling. Given their central role in electrical excitability, it is not surprising that (a) inherited mutations in genes encoding for Nav channels and their accessory subunits have been linked to excitability disorders in brain, muscle, and heart; and (b) Nav channels are targeted by various drugs and naturally occurring toxins. Although the overall architecture and behavior of these channels are likely to be similar to the more well-studied voltage-gated potassium channels, eukaryotic Nav channels lack structural and functional symmetry, a notable difference that has implications for gating and selectivity. Activation of voltage-sensing modules of the first three domains in Nav channels is sufficient to open the channel pore, whereas movement of the domain IV voltage sensor is correlated with inactivation. Also, structure–function studies of eukaryotic Nav channels show that a set of amino acids in the selectivity filter, referred to as DEKA locus, is essential for Na+ selectivity. Structures of prokaryotic Nav channels have also shed new light on mechanisms of drug block. These structures exhibit lateral fenestrations that are large enough to allow drugs or lipophilic molecules to gain access into the inner vestibule, suggesting that this might be the passage for drug entry into a closed channel. In this Review, we will synthesize our current understanding of Nav channel gating mechanisms, ion selectivity and permeation, and modulation by therapeutics and toxins in light of the new structures of the prokaryotic Nav channels that, for the time being, serve as structural models of their eukaryotic counterparts.
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Affiliation(s)
- Christopher A Ahern
- Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, IA 52242
| | - Jian Payandeh
- Department of Structural Biology, Genentech, Inc., South San Francisco, CA 94080
| | - Frank Bosmans
- Department of Physiology and Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, School of Medicine, Baltimore, MD 21205 Department of Physiology and Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, School of Medicine, Baltimore, MD 21205
| | - Baron Chanda
- Department of Neuroscience and Department of Biomolecular Chemistry, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI 53705 Department of Neuroscience and Department of Biomolecular Chemistry, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI 53705
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23
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Meisler MH, Helman G, Hammer MF, Fureman BE, Gaillard WD, Goldin AL, Hirose S, Ishii A, Kroner BL, Lossin C, Mefford HC, Parent JM, Patel M, Schreiber J, Stewart R, Whittemore V, Wilcox K, Wagnon JL, Pearl PL, Vanderver A, Scheffer IE. SCN8A encephalopathy: Research progress and prospects. Epilepsia 2016; 57:1027-35. [PMID: 27270488 PMCID: PMC5495462 DOI: 10.1111/epi.13422] [Citation(s) in RCA: 97] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/26/2016] [Indexed: 01/15/2023]
Abstract
On April 21, 2015, the first SCN8A Encephalopathy Research Group convened in Washington, DC, to assess current research into clinical and pathogenic features of the disorder and prepare an agenda for future research collaborations. The group comprised clinical and basic scientists and representatives of patient advocacy groups. SCN8A encephalopathy is a rare disorder caused by de novo missense mutations of the sodium channel gene SCN8A, which encodes the neuronal sodium channel Nav 1.6. Since the initial description in 2012, approximately 140 affected individuals have been reported in publications or by SCN8A family groups. As a result, an understanding of the severe impact of SCN8A mutations is beginning to emerge. Defining a genetic epilepsy syndrome goes beyond identification of molecular etiology. Topics discussed at this meeting included (1) comparison between mutations of SCN8A and the SCN1A mutations in Dravet syndrome, (2) biophysical properties of the Nav 1.6 channel, (3) electrophysiologic effects of patient mutations on channel properties, (4) cell and animal models of SCN8A encephalopathy, (5) drug screening strategies, (6) the phenotypic spectrum of SCN8A encephalopathy, and (7) efforts to develop a bioregistry. A panel discussion of gaps in bioregistry, biobanking, and clinical outcomes data was followed by a planning session for improved integration of clinical and basic science research. Although SCN8A encephalopathy was identified only recently, there has been rapid progress in functional analysis and phenotypic classification. The focus is now shifting from identification of the underlying molecular cause to the development of strategies for drug screening and prioritized patient care.
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Affiliation(s)
- Miriam H. Meisler
- Department of Human Genetics, University of Michigan, Ann Arbor, Michigan, U.S.A
| | - Guy Helman
- Department of Neurology, Children’s National Health System, Washington, District of Columbia, U.S.A
- Center for Genetic Medicine Research, Children’s National Health System, Washington, District of Columbia, U.S.A
| | - Michael F. Hammer
- ARL Division of Biotechnology, University of Arizona, Tucson, Arizona, U.S.A
| | - Brandy E. Fureman
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, U.S.A
| | - William D. Gaillard
- Department of Neurology, Children’s National Health System, Washington, District of Columbia, U.S.A
- Center for Neuroscience Research, Children’s National Health System, Washington, District of Columbia, U.S.A
| | - Alan L. Goldin
- Microbiology & Molecular Genetics and Anatomy & Neurobiology, University of California, Irvine, California, U.S.A
| | - Shinichi Hirose
- Department of Pediatrics, Fukuoka University School of Medicine, Fukuoka, Japan
| | - Atsushi Ishii
- Department of Pediatrics, Fukuoka University School of Medicine, Fukuoka, Japan
| | - Barbara L. Kroner
- Biostatistics and Epidemiology, RTI International, Rockville, Maryland, U.S.A
| | - Christoph Lossin
- Department of Neurology, School of Medicine, University of California Davis, Sacramento, California, U.S.A
| | - Heather C. Mefford
- Division of Genetic Medicine, Department of Pediatrics, University of Washington, Seattle, Washington, U.S.A
| | - Jack M. Parent
- Department of Neurology, University of Michigan Medical Center and VA Ann Arbor Healthcare System, Ann Arbor, Michigan, U.S.A
| | - Manoj Patel
- Department of Anesthesiology, University of Virginia Health System, Charlottesville, Virginia, U.S.A
| | - John Schreiber
- Department of Neurology, Children’s National Health System, Washington, District of Columbia, U.S.A
| | - Randall Stewart
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, U.S.A
| | - Vicky Whittemore
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, U.S.A
| | - Karen Wilcox
- Anticonvulsant Drug Development Program, Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, Utah, U.S.A
| | - Jacy L Wagnon
- Department of Human Genetics, University of Michigan, Ann Arbor, Michigan, U.S.A
| | - Phillip L. Pearl
- Department of Neurology, Boston Children’s Hospital, Harvard Medical School, Boston, Massachusetts, U.S.A
| | - Adeline Vanderver
- Department of Neurology, Children’s National Health System, Washington, District of Columbia, U.S.A
- Center for Genetic Medicine Research, Children’s National Health System, Washington, District of Columbia, U.S.A
- Department of Integrated Systems Biology and Pediatrics, George Washington University, Washington, District of Columbia, U.S.A
| | - Ingrid E. Scheffer
- Department of Neurology, Royal Children’s Hospital, Melbourne, Victoria, Australia
- Department of Paediatrics, University of Melbourne, Melbourne, Victoria, Australia
- Department of Medicine, Epilepsy Research Centre, University of Melbourne, Austin Health, Melbourne, Victoria, Australia
- Florey Institute of Neurosciences and Mental Health, Melbourne, Victoria, Australia
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24
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DeMarco KR, Clancy CE. Cardiac Na Channels: Structure to Function. CURRENT TOPICS IN MEMBRANES 2016; 78:287-311. [PMID: 27586288 DOI: 10.1016/bs.ctm.2016.05.001] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Heart rhythms arise from electrical activity generated by precisely timed opening and closing of ion channels in individual cardiac myocytes. Opening of the primary cardiac voltage-gated sodium (NaV1.5) channel initiates cellular depolarization and the propagation of an electrical action potential that promotes coordinated contraction of the heart. The regularity of these contractile waves is critically important since it drives the primary function of the heart: to act as a pump that delivers blood to the brain and vital organs. When electrical activity goes awry during a cardiac arrhythmia, the pump does not function, the brain does not receive oxygenated blood, and death ensues. Perturbations to NaV1.5 may alter the structure, and hence the function, of the ion channel and are associated downstream with a wide variety of cardiac conduction pathologies, such as arrhythmias.
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Affiliation(s)
- K R DeMarco
- University of California, Davis, Davis, CA, United States
| | - C E Clancy
- University of California, Davis, Davis, CA, United States
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25
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Barbosa C, Cummins TR. Unusual Voltage-Gated Sodium Currents as Targets for Pain. CURRENT TOPICS IN MEMBRANES 2016; 78:599-638. [PMID: 27586296 DOI: 10.1016/bs.ctm.2015.12.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Pain is a serious health problem that impacts the lives of many individuals. Hyperexcitability of peripheral sensory neurons contributes to both acute and chronic pain syndromes. Because voltage-gated sodium currents are crucial to the transmission of electrical signals in peripheral sensory neurons, the channels that underlie these currents are attractive targets for pain therapeutics. Sodium currents and channels in peripheral sensory neurons are complex. Multiple-channel isoforms contribute to the macroscopic currents in nociceptive sensory neurons. These different isoforms exhibit substantial variations in their kinetics and pharmacology. Furthermore, sodium current complexity is enhanced by an array of interacting proteins that can substantially modify the properties of voltage-gated sodium channels. Resurgent sodium currents, atypical currents that can enhance recovery from inactivation and neuronal firing, are increasingly being recognized as playing potentially important roles in sensory neuron hyperexcitability and pain sensations. Here we discuss unusual sodium channels and currents that have been identified in nociceptive sensory neurons, describe what is known about the molecular determinants of the complex sodium currents in these neurons. Finally, we provide an overview of therapeutic strategies to target voltage-gated sodium currents in nociceptive neurons.
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Affiliation(s)
- C Barbosa
- Indiana University School of Medicine, Indianapolis, IN, United States
| | - T R Cummins
- Indiana University School of Medicine, Indianapolis, IN, United States
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26
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Loussouarn G, Sternberg D, Nicole S, Marionneau C, Le Bouffant F, Toumaniantz G, Barc J, Malak OA, Fressart V, Péréon Y, Baró I, Charpentier F. Physiological and Pathophysiological Insights of Nav1.4 and Nav1.5 Comparison. Front Pharmacol 2016; 6:314. [PMID: 26834636 PMCID: PMC4712308 DOI: 10.3389/fphar.2015.00314] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Accepted: 12/21/2015] [Indexed: 12/19/2022] Open
Abstract
Mutations in Nav1.4 and Nav1.5 α-subunits have been associated with muscular and cardiac channelopathies, respectively. Despite intense research on the structure and function of these channels, a lot of information is still missing to delineate the various physiological and pathophysiological processes underlying their activity at the molecular level. Nav1.4 and Nav1.5 sequences are similar, suggesting structural and functional homologies between the two orthologous channels. This also suggests that any characteristics described for one channel subunit may shed light on the properties of the counterpart channel subunit. In this review article, after a brief clinical description of the muscular and cardiac channelopathies related to Nav1.4 and Nav1.5 mutations, respectively, we compare the knowledge accumulated in different aspects of the expression and function of Nav1.4 and Nav1.5 α-subunits: the regulation of the two encoding genes (SCN4A and SCN5A), the associated/regulatory proteins and at last, the functional effect of the same missense mutations detected in Nav1.4 and Nav1.5. First, it appears that more is known on Nav1.5 expression and accessory proteins. Because of the high homologies of Nav1.5 binding sites and equivalent Nav1.4 sites, Nav1.5-related results may guide future investigations on Nav1.4. Second, the analysis of the same missense mutations in Nav1.4 and Nav1.5 revealed intriguing similarities regarding their effects on membrane excitability and alteration in channel biophysics. We believe that such comparison may bring new cues to the physiopathology of cardiac and muscular diseases.
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Affiliation(s)
- Gildas Loussouarn
- Institut National de la Santé et de la Recherche Médicale, UMR 1087, l'Institut du ThoraxNantes, France; Centre National de la Recherche Scientifique, UMR 6291Nantes, France; Université de NantesNantes, France
| | - Damien Sternberg
- Institut National de la Santé et de la Recherche Médicale, U1127Paris, France; Sorbonne Universités, Université Pierre-et-Marie-Curie, UMR S1127Paris, France; Centre National de la Recherche Scientifique, UMR 7225Paris, France; Institut du Cerveau et de la Moelle Épinière, ICMParis, France; Assistance Publique - Hôpitaux de Paris (AP-HP), Centres de Référence des Canalopathies Musculaires et des Maladies Neuro-musculaires Paris-EstParis, France; Assistance Publique - Hôpitaux de Paris (AP-HP), Hôpital de la Pitié Salpêtrière, Service de Biochimie Métabolique, Unité de Cardiogénétique et MyogénétiqueParis, France
| | - Sophie Nicole
- Institut National de la Santé et de la Recherche Médicale, U1127Paris, France; Sorbonne Universités, Université Pierre-et-Marie-Curie, UMR S1127Paris, France; Centre National de la Recherche Scientifique, UMR 7225Paris, France; Institut du Cerveau et de la Moelle Épinière, ICMParis, France
| | - Céline Marionneau
- Institut National de la Santé et de la Recherche Médicale, UMR 1087, l'Institut du ThoraxNantes, France; Centre National de la Recherche Scientifique, UMR 6291Nantes, France; Université de NantesNantes, France
| | - Francoise Le Bouffant
- Institut National de la Santé et de la Recherche Médicale, UMR 1087, l'Institut du ThoraxNantes, France; Centre National de la Recherche Scientifique, UMR 6291Nantes, France; Université de NantesNantes, France
| | - Gilles Toumaniantz
- Institut National de la Santé et de la Recherche Médicale, UMR 1087, l'Institut du ThoraxNantes, France; Centre National de la Recherche Scientifique, UMR 6291Nantes, France; Université de NantesNantes, France
| | - Julien Barc
- Institut National de la Santé et de la Recherche Médicale, UMR 1087, l'Institut du ThoraxNantes, France; Centre National de la Recherche Scientifique, UMR 6291Nantes, France; Université de NantesNantes, France
| | - Olfat A Malak
- Institut National de la Santé et de la Recherche Médicale, UMR 1087, l'Institut du ThoraxNantes, France; Centre National de la Recherche Scientifique, UMR 6291Nantes, France; Université de NantesNantes, France
| | - Véronique Fressart
- Assistance Publique - Hôpitaux de Paris (AP-HP), Hôpital de la Pitié Salpêtrière, Service de Biochimie Métabolique, Unité de Cardiogénétique et Myogénétique Paris, France
| | - Yann Péréon
- Centre Hospitalier Universitaire de Nantes, Centre de Référence Maladies Neuromusculaires Nantes-AngersNantes, France; Atlantic Gene Therapies - Biotherapy Institute for Rare DiseasesNantes, France
| | - Isabelle Baró
- Institut National de la Santé et de la Recherche Médicale, UMR 1087, l'Institut du ThoraxNantes, France; Centre National de la Recherche Scientifique, UMR 6291Nantes, France; Université de NantesNantes, France
| | - Flavien Charpentier
- Institut National de la Santé et de la Recherche Médicale, UMR 1087, l'Institut du ThoraxNantes, France; Centre National de la Recherche Scientifique, UMR 6291Nantes, France; Université de NantesNantes, France; Centre Hospitalier Universitaire de Nantes, l'Institut du ThoraxNantes, France
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27
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Habbout K, Poulin H, Rivier F, Giuliano S, Sternberg D, Fontaine B, Eymard B, Morales RJ, Echenne B, King L, Hanna MG, Männikkö R, Chahine M, Nicole S, Bendahhou S. A recessive Nav1.4 mutation underlies congenital myasthenic syndrome with periodic paralysis. Neurology 2015; 86:161-9. [PMID: 26659129 DOI: 10.1212/wnl.0000000000002264] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2015] [Accepted: 09/08/2015] [Indexed: 01/30/2023] Open
Abstract
OBJECTIVE To determine the molecular basis of a complex phenotype of congenital muscle weakness observed in an isolated but consanguineous patient. METHODS The proband was evaluated clinically and neurophysiologically over a period of 15 years. Genetic testing of candidate genes was performed. Functional characterization of the candidate mutation was done in mammalian cell background using whole cell patch clamp technique. RESULTS The proband had fatigable muscle weakness characteristic of congenital myasthenic syndrome with acute and reversible attacks of most severe muscle weakness as observed in periodic paralysis. We identified a novel homozygous SCN4A mutation (p.R1454W) linked to this recessively inherited phenotype. The p.R1454W substitution induced an important enhancement of fast and slow inactivation, a slower recovery for these inactivated states, and a frequency-dependent regulation of Nav1.4 channels in the heterologous expression system. CONCLUSION We identified a novel loss-of-function mutation of Nav1.4 that leads to a recessive phenotype combining clinical symptoms and signs of congenital myasthenic syndrome and periodic paralysis, probably by decreasing channel availability for muscle action potential genesis at the neuromuscular junction and propagation along the sarcolemma.
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Affiliation(s)
- Karima Habbout
- From UMR7370 CNRS (K.H., S.G., S.B.), LP2M, Labex ICST, University Nice Sophia-Antipolis, Faculté de Médecine, Nice, France; Centre de Recherche (H.P., M.C.), Institut Universitaire en Santé Mentale de Québec; Department of Medicine (H.P., M.C.), Université Laval, Québec City, Canada; CHRU Montpellier (F.R., R.J.M., B.E.), Neuropédiatrie & Centre de Référence Maladies Neuromusculaires, Montpellier; Université de Montpellier (F.R., B.E.); INSERM (F.R.), U1046, CNRS, UMR9214, Montpellier; INSERM (D.S., B.F., B.E., S.N.), U1127, Paris; Sorbonne Universités (D.S., B.F., B.E., S.N.), UPMC University Paris 6, UMR S1127; CNRS (D.S., B.F., B.E., S.N.), UMR 7225, Paris; Institut du Cerveau et de la Moelle Épinière (D.S., B.F., B.E., S.N.), ICM, Paris; AP-HP (D.S., B.F., B.E.), Centres de Référence des Canalopathies Musculaires et des Maladies Neuro-musculaires Paris-Est, Service de Biochimie Métabolique, Hôpital de la Pitié Salpêtrière, France; and MRC Centre for Neuromuscular Diseases (L.K., M.G.H., R.M.), UCL Institute of Neurology, London, UK
| | - Hugo Poulin
- From UMR7370 CNRS (K.H., S.G., S.B.), LP2M, Labex ICST, University Nice Sophia-Antipolis, Faculté de Médecine, Nice, France; Centre de Recherche (H.P., M.C.), Institut Universitaire en Santé Mentale de Québec; Department of Medicine (H.P., M.C.), Université Laval, Québec City, Canada; CHRU Montpellier (F.R., R.J.M., B.E.), Neuropédiatrie & Centre de Référence Maladies Neuromusculaires, Montpellier; Université de Montpellier (F.R., B.E.); INSERM (F.R.), U1046, CNRS, UMR9214, Montpellier; INSERM (D.S., B.F., B.E., S.N.), U1127, Paris; Sorbonne Universités (D.S., B.F., B.E., S.N.), UPMC University Paris 6, UMR S1127; CNRS (D.S., B.F., B.E., S.N.), UMR 7225, Paris; Institut du Cerveau et de la Moelle Épinière (D.S., B.F., B.E., S.N.), ICM, Paris; AP-HP (D.S., B.F., B.E.), Centres de Référence des Canalopathies Musculaires et des Maladies Neuro-musculaires Paris-Est, Service de Biochimie Métabolique, Hôpital de la Pitié Salpêtrière, France; and MRC Centre for Neuromuscular Diseases (L.K., M.G.H., R.M.), UCL Institute of Neurology, London, UK
| | - François Rivier
- From UMR7370 CNRS (K.H., S.G., S.B.), LP2M, Labex ICST, University Nice Sophia-Antipolis, Faculté de Médecine, Nice, France; Centre de Recherche (H.P., M.C.), Institut Universitaire en Santé Mentale de Québec; Department of Medicine (H.P., M.C.), Université Laval, Québec City, Canada; CHRU Montpellier (F.R., R.J.M., B.E.), Neuropédiatrie & Centre de Référence Maladies Neuromusculaires, Montpellier; Université de Montpellier (F.R., B.E.); INSERM (F.R.), U1046, CNRS, UMR9214, Montpellier; INSERM (D.S., B.F., B.E., S.N.), U1127, Paris; Sorbonne Universités (D.S., B.F., B.E., S.N.), UPMC University Paris 6, UMR S1127; CNRS (D.S., B.F., B.E., S.N.), UMR 7225, Paris; Institut du Cerveau et de la Moelle Épinière (D.S., B.F., B.E., S.N.), ICM, Paris; AP-HP (D.S., B.F., B.E.), Centres de Référence des Canalopathies Musculaires et des Maladies Neuro-musculaires Paris-Est, Service de Biochimie Métabolique, Hôpital de la Pitié Salpêtrière, France; and MRC Centre for Neuromuscular Diseases (L.K., M.G.H., R.M.), UCL Institute of Neurology, London, UK
| | - Serena Giuliano
- From UMR7370 CNRS (K.H., S.G., S.B.), LP2M, Labex ICST, University Nice Sophia-Antipolis, Faculté de Médecine, Nice, France; Centre de Recherche (H.P., M.C.), Institut Universitaire en Santé Mentale de Québec; Department of Medicine (H.P., M.C.), Université Laval, Québec City, Canada; CHRU Montpellier (F.R., R.J.M., B.E.), Neuropédiatrie & Centre de Référence Maladies Neuromusculaires, Montpellier; Université de Montpellier (F.R., B.E.); INSERM (F.R.), U1046, CNRS, UMR9214, Montpellier; INSERM (D.S., B.F., B.E., S.N.), U1127, Paris; Sorbonne Universités (D.S., B.F., B.E., S.N.), UPMC University Paris 6, UMR S1127; CNRS (D.S., B.F., B.E., S.N.), UMR 7225, Paris; Institut du Cerveau et de la Moelle Épinière (D.S., B.F., B.E., S.N.), ICM, Paris; AP-HP (D.S., B.F., B.E.), Centres de Référence des Canalopathies Musculaires et des Maladies Neuro-musculaires Paris-Est, Service de Biochimie Métabolique, Hôpital de la Pitié Salpêtrière, France; and MRC Centre for Neuromuscular Diseases (L.K., M.G.H., R.M.), UCL Institute of Neurology, London, UK
| | - Damien Sternberg
- From UMR7370 CNRS (K.H., S.G., S.B.), LP2M, Labex ICST, University Nice Sophia-Antipolis, Faculté de Médecine, Nice, France; Centre de Recherche (H.P., M.C.), Institut Universitaire en Santé Mentale de Québec; Department of Medicine (H.P., M.C.), Université Laval, Québec City, Canada; CHRU Montpellier (F.R., R.J.M., B.E.), Neuropédiatrie & Centre de Référence Maladies Neuromusculaires, Montpellier; Université de Montpellier (F.R., B.E.); INSERM (F.R.), U1046, CNRS, UMR9214, Montpellier; INSERM (D.S., B.F., B.E., S.N.), U1127, Paris; Sorbonne Universités (D.S., B.F., B.E., S.N.), UPMC University Paris 6, UMR S1127; CNRS (D.S., B.F., B.E., S.N.), UMR 7225, Paris; Institut du Cerveau et de la Moelle Épinière (D.S., B.F., B.E., S.N.), ICM, Paris; AP-HP (D.S., B.F., B.E.), Centres de Référence des Canalopathies Musculaires et des Maladies Neuro-musculaires Paris-Est, Service de Biochimie Métabolique, Hôpital de la Pitié Salpêtrière, France; and MRC Centre for Neuromuscular Diseases (L.K., M.G.H., R.M.), UCL Institute of Neurology, London, UK
| | - Bertrand Fontaine
- From UMR7370 CNRS (K.H., S.G., S.B.), LP2M, Labex ICST, University Nice Sophia-Antipolis, Faculté de Médecine, Nice, France; Centre de Recherche (H.P., M.C.), Institut Universitaire en Santé Mentale de Québec; Department of Medicine (H.P., M.C.), Université Laval, Québec City, Canada; CHRU Montpellier (F.R., R.J.M., B.E.), Neuropédiatrie & Centre de Référence Maladies Neuromusculaires, Montpellier; Université de Montpellier (F.R., B.E.); INSERM (F.R.), U1046, CNRS, UMR9214, Montpellier; INSERM (D.S., B.F., B.E., S.N.), U1127, Paris; Sorbonne Universités (D.S., B.F., B.E., S.N.), UPMC University Paris 6, UMR S1127; CNRS (D.S., B.F., B.E., S.N.), UMR 7225, Paris; Institut du Cerveau et de la Moelle Épinière (D.S., B.F., B.E., S.N.), ICM, Paris; AP-HP (D.S., B.F., B.E.), Centres de Référence des Canalopathies Musculaires et des Maladies Neuro-musculaires Paris-Est, Service de Biochimie Métabolique, Hôpital de la Pitié Salpêtrière, France; and MRC Centre for Neuromuscular Diseases (L.K., M.G.H., R.M.), UCL Institute of Neurology, London, UK
| | - Bruno Eymard
- From UMR7370 CNRS (K.H., S.G., S.B.), LP2M, Labex ICST, University Nice Sophia-Antipolis, Faculté de Médecine, Nice, France; Centre de Recherche (H.P., M.C.), Institut Universitaire en Santé Mentale de Québec; Department of Medicine (H.P., M.C.), Université Laval, Québec City, Canada; CHRU Montpellier (F.R., R.J.M., B.E.), Neuropédiatrie & Centre de Référence Maladies Neuromusculaires, Montpellier; Université de Montpellier (F.R., B.E.); INSERM (F.R.), U1046, CNRS, UMR9214, Montpellier; INSERM (D.S., B.F., B.E., S.N.), U1127, Paris; Sorbonne Universités (D.S., B.F., B.E., S.N.), UPMC University Paris 6, UMR S1127; CNRS (D.S., B.F., B.E., S.N.), UMR 7225, Paris; Institut du Cerveau et de la Moelle Épinière (D.S., B.F., B.E., S.N.), ICM, Paris; AP-HP (D.S., B.F., B.E.), Centres de Référence des Canalopathies Musculaires et des Maladies Neuro-musculaires Paris-Est, Service de Biochimie Métabolique, Hôpital de la Pitié Salpêtrière, France; and MRC Centre for Neuromuscular Diseases (L.K., M.G.H., R.M.), UCL Institute of Neurology, London, UK
| | - Raul Juntas Morales
- From UMR7370 CNRS (K.H., S.G., S.B.), LP2M, Labex ICST, University Nice Sophia-Antipolis, Faculté de Médecine, Nice, France; Centre de Recherche (H.P., M.C.), Institut Universitaire en Santé Mentale de Québec; Department of Medicine (H.P., M.C.), Université Laval, Québec City, Canada; CHRU Montpellier (F.R., R.J.M., B.E.), Neuropédiatrie & Centre de Référence Maladies Neuromusculaires, Montpellier; Université de Montpellier (F.R., B.E.); INSERM (F.R.), U1046, CNRS, UMR9214, Montpellier; INSERM (D.S., B.F., B.E., S.N.), U1127, Paris; Sorbonne Universités (D.S., B.F., B.E., S.N.), UPMC University Paris 6, UMR S1127; CNRS (D.S., B.F., B.E., S.N.), UMR 7225, Paris; Institut du Cerveau et de la Moelle Épinière (D.S., B.F., B.E., S.N.), ICM, Paris; AP-HP (D.S., B.F., B.E.), Centres de Référence des Canalopathies Musculaires et des Maladies Neuro-musculaires Paris-Est, Service de Biochimie Métabolique, Hôpital de la Pitié Salpêtrière, France; and MRC Centre for Neuromuscular Diseases (L.K., M.G.H., R.M.), UCL Institute of Neurology, London, UK
| | - Bernard Echenne
- From UMR7370 CNRS (K.H., S.G., S.B.), LP2M, Labex ICST, University Nice Sophia-Antipolis, Faculté de Médecine, Nice, France; Centre de Recherche (H.P., M.C.), Institut Universitaire en Santé Mentale de Québec; Department of Medicine (H.P., M.C.), Université Laval, Québec City, Canada; CHRU Montpellier (F.R., R.J.M., B.E.), Neuropédiatrie & Centre de Référence Maladies Neuromusculaires, Montpellier; Université de Montpellier (F.R., B.E.); INSERM (F.R.), U1046, CNRS, UMR9214, Montpellier; INSERM (D.S., B.F., B.E., S.N.), U1127, Paris; Sorbonne Universités (D.S., B.F., B.E., S.N.), UPMC University Paris 6, UMR S1127; CNRS (D.S., B.F., B.E., S.N.), UMR 7225, Paris; Institut du Cerveau et de la Moelle Épinière (D.S., B.F., B.E., S.N.), ICM, Paris; AP-HP (D.S., B.F., B.E.), Centres de Référence des Canalopathies Musculaires et des Maladies Neuro-musculaires Paris-Est, Service de Biochimie Métabolique, Hôpital de la Pitié Salpêtrière, France; and MRC Centre for Neuromuscular Diseases (L.K., M.G.H., R.M.), UCL Institute of Neurology, London, UK
| | - Louise King
- From UMR7370 CNRS (K.H., S.G., S.B.), LP2M, Labex ICST, University Nice Sophia-Antipolis, Faculté de Médecine, Nice, France; Centre de Recherche (H.P., M.C.), Institut Universitaire en Santé Mentale de Québec; Department of Medicine (H.P., M.C.), Université Laval, Québec City, Canada; CHRU Montpellier (F.R., R.J.M., B.E.), Neuropédiatrie & Centre de Référence Maladies Neuromusculaires, Montpellier; Université de Montpellier (F.R., B.E.); INSERM (F.R.), U1046, CNRS, UMR9214, Montpellier; INSERM (D.S., B.F., B.E., S.N.), U1127, Paris; Sorbonne Universités (D.S., B.F., B.E., S.N.), UPMC University Paris 6, UMR S1127; CNRS (D.S., B.F., B.E., S.N.), UMR 7225, Paris; Institut du Cerveau et de la Moelle Épinière (D.S., B.F., B.E., S.N.), ICM, Paris; AP-HP (D.S., B.F., B.E.), Centres de Référence des Canalopathies Musculaires et des Maladies Neuro-musculaires Paris-Est, Service de Biochimie Métabolique, Hôpital de la Pitié Salpêtrière, France; and MRC Centre for Neuromuscular Diseases (L.K., M.G.H., R.M.), UCL Institute of Neurology, London, UK
| | - Michael G Hanna
- From UMR7370 CNRS (K.H., S.G., S.B.), LP2M, Labex ICST, University Nice Sophia-Antipolis, Faculté de Médecine, Nice, France; Centre de Recherche (H.P., M.C.), Institut Universitaire en Santé Mentale de Québec; Department of Medicine (H.P., M.C.), Université Laval, Québec City, Canada; CHRU Montpellier (F.R., R.J.M., B.E.), Neuropédiatrie & Centre de Référence Maladies Neuromusculaires, Montpellier; Université de Montpellier (F.R., B.E.); INSERM (F.R.), U1046, CNRS, UMR9214, Montpellier; INSERM (D.S., B.F., B.E., S.N.), U1127, Paris; Sorbonne Universités (D.S., B.F., B.E., S.N.), UPMC University Paris 6, UMR S1127; CNRS (D.S., B.F., B.E., S.N.), UMR 7225, Paris; Institut du Cerveau et de la Moelle Épinière (D.S., B.F., B.E., S.N.), ICM, Paris; AP-HP (D.S., B.F., B.E.), Centres de Référence des Canalopathies Musculaires et des Maladies Neuro-musculaires Paris-Est, Service de Biochimie Métabolique, Hôpital de la Pitié Salpêtrière, France; and MRC Centre for Neuromuscular Diseases (L.K., M.G.H., R.M.), UCL Institute of Neurology, London, UK
| | - Roope Männikkö
- From UMR7370 CNRS (K.H., S.G., S.B.), LP2M, Labex ICST, University Nice Sophia-Antipolis, Faculté de Médecine, Nice, France; Centre de Recherche (H.P., M.C.), Institut Universitaire en Santé Mentale de Québec; Department of Medicine (H.P., M.C.), Université Laval, Québec City, Canada; CHRU Montpellier (F.R., R.J.M., B.E.), Neuropédiatrie & Centre de Référence Maladies Neuromusculaires, Montpellier; Université de Montpellier (F.R., B.E.); INSERM (F.R.), U1046, CNRS, UMR9214, Montpellier; INSERM (D.S., B.F., B.E., S.N.), U1127, Paris; Sorbonne Universités (D.S., B.F., B.E., S.N.), UPMC University Paris 6, UMR S1127; CNRS (D.S., B.F., B.E., S.N.), UMR 7225, Paris; Institut du Cerveau et de la Moelle Épinière (D.S., B.F., B.E., S.N.), ICM, Paris; AP-HP (D.S., B.F., B.E.), Centres de Référence des Canalopathies Musculaires et des Maladies Neuro-musculaires Paris-Est, Service de Biochimie Métabolique, Hôpital de la Pitié Salpêtrière, France; and MRC Centre for Neuromuscular Diseases (L.K., M.G.H., R.M.), UCL Institute of Neurology, London, UK
| | - Mohamed Chahine
- From UMR7370 CNRS (K.H., S.G., S.B.), LP2M, Labex ICST, University Nice Sophia-Antipolis, Faculté de Médecine, Nice, France; Centre de Recherche (H.P., M.C.), Institut Universitaire en Santé Mentale de Québec; Department of Medicine (H.P., M.C.), Université Laval, Québec City, Canada; CHRU Montpellier (F.R., R.J.M., B.E.), Neuropédiatrie & Centre de Référence Maladies Neuromusculaires, Montpellier; Université de Montpellier (F.R., B.E.); INSERM (F.R.), U1046, CNRS, UMR9214, Montpellier; INSERM (D.S., B.F., B.E., S.N.), U1127, Paris; Sorbonne Universités (D.S., B.F., B.E., S.N.), UPMC University Paris 6, UMR S1127; CNRS (D.S., B.F., B.E., S.N.), UMR 7225, Paris; Institut du Cerveau et de la Moelle Épinière (D.S., B.F., B.E., S.N.), ICM, Paris; AP-HP (D.S., B.F., B.E.), Centres de Référence des Canalopathies Musculaires et des Maladies Neuro-musculaires Paris-Est, Service de Biochimie Métabolique, Hôpital de la Pitié Salpêtrière, France; and MRC Centre for Neuromuscular Diseases (L.K., M.G.H., R.M.), UCL Institute of Neurology, London, UK
| | - Sophie Nicole
- From UMR7370 CNRS (K.H., S.G., S.B.), LP2M, Labex ICST, University Nice Sophia-Antipolis, Faculté de Médecine, Nice, France; Centre de Recherche (H.P., M.C.), Institut Universitaire en Santé Mentale de Québec; Department of Medicine (H.P., M.C.), Université Laval, Québec City, Canada; CHRU Montpellier (F.R., R.J.M., B.E.), Neuropédiatrie & Centre de Référence Maladies Neuromusculaires, Montpellier; Université de Montpellier (F.R., B.E.); INSERM (F.R.), U1046, CNRS, UMR9214, Montpellier; INSERM (D.S., B.F., B.E., S.N.), U1127, Paris; Sorbonne Universités (D.S., B.F., B.E., S.N.), UPMC University Paris 6, UMR S1127; CNRS (D.S., B.F., B.E., S.N.), UMR 7225, Paris; Institut du Cerveau et de la Moelle Épinière (D.S., B.F., B.E., S.N.), ICM, Paris; AP-HP (D.S., B.F., B.E.), Centres de Référence des Canalopathies Musculaires et des Maladies Neuro-musculaires Paris-Est, Service de Biochimie Métabolique, Hôpital de la Pitié Salpêtrière, France; and MRC Centre for Neuromuscular Diseases (L.K., M.G.H., R.M.), UCL Institute of Neurology, London, UK
| | - Said Bendahhou
- From UMR7370 CNRS (K.H., S.G., S.B.), LP2M, Labex ICST, University Nice Sophia-Antipolis, Faculté de Médecine, Nice, France; Centre de Recherche (H.P., M.C.), Institut Universitaire en Santé Mentale de Québec; Department of Medicine (H.P., M.C.), Université Laval, Québec City, Canada; CHRU Montpellier (F.R., R.J.M., B.E.), Neuropédiatrie & Centre de Référence Maladies Neuromusculaires, Montpellier; Université de Montpellier (F.R., B.E.); INSERM (F.R.), U1046, CNRS, UMR9214, Montpellier; INSERM (D.S., B.F., B.E., S.N.), U1127, Paris; Sorbonne Universités (D.S., B.F., B.E., S.N.), UPMC University Paris 6, UMR S1127; CNRS (D.S., B.F., B.E., S.N.), UMR 7225, Paris; Institut du Cerveau et de la Moelle Épinière (D.S., B.F., B.E., S.N.), ICM, Paris; AP-HP (D.S., B.F., B.E.), Centres de Référence des Canalopathies Musculaires et des Maladies Neuro-musculaires Paris-Est, Service de Biochimie Métabolique, Hôpital de la Pitié Salpêtrière, France; and MRC Centre for Neuromuscular Diseases (L.K., M.G.H., R.M.), UCL Institute of Neurology, London, UK.
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28
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Gawali VS, Lukacs P, Cervenka R, Koenig X, Rubi L, Hilber K, Sandtner W, Todt H. Mechanism of Modification, by Lidocaine, of Fast and Slow Recovery from Inactivation of Voltage-Gated Na⁺ Channels. Mol Pharmacol 2015; 88:866-79. [PMID: 26358763 DOI: 10.1124/mol.115.099580] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2015] [Accepted: 09/09/2015] [Indexed: 11/22/2022] Open
Abstract
The clinically important suppression of high-frequency discharges of excitable cells by local anesthetics (LA) is largely determined by drug-induced prolongation of the time course of repriming (recovery from inactivation) of voltage-gated Na(+) channels. This prolongation may result from periodic drug-binding to a high-affinity binding site during the action potentials and subsequent slow dissociation from the site between action potentials ("dissociation hypothesis"). For many drugs it has been suggested that the fast inactivated state represents the high-affinity binding state. Alternatively, LAs may bind with high affinity to a native slow-inactivated state, thereby accelerating the development of this state during action potentials ("stabilization hypothesis"). In this case, slow recovery between action potentials occurs from enhanced native slow inactivation. To test these two hypotheses we produced serial cysteine mutations of domain IV segment 6 in rNav1.4 that resulted in constructs with varying propensities to enter fast- and slow-inactivated states. We tested the effect of the LA lidocaine on the time course of recovery from short and long depolarizing prepulses, which, under drug-free conditions, recruited mainly fast- and slow-inactivated states, respectively. Among the tested constructs the mutation-induced changes in native slow recovery induced by long depolarizations were not correlated with the respective lidocaine-induced slow recovery after short depolarizations. On the other hand, for long depolarizations the mutation-induced alterations in native slow recovery were significantly correlated with the kinetics of lidocaine-induced slow recovery. These results favor the "dissociation hypothesis" for short depolarizations but the "stabilization hypothesis" for long depolarizations.
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Affiliation(s)
- Vaibhavkumar S Gawali
- Center for Physiology and Pharmacology, Department of Neurophysiology and Neuropharmacology (V.S.G., P.L., R.C., X.K., L.R., K.H., H.T.) and Center for Physiology and Pharmacology (W.S.), Medical University of Vienna, Vienna, Austria
| | - Peter Lukacs
- Center for Physiology and Pharmacology, Department of Neurophysiology and Neuropharmacology (V.S.G., P.L., R.C., X.K., L.R., K.H., H.T.) and Center for Physiology and Pharmacology (W.S.), Medical University of Vienna, Vienna, Austria
| | - Rene Cervenka
- Center for Physiology and Pharmacology, Department of Neurophysiology and Neuropharmacology (V.S.G., P.L., R.C., X.K., L.R., K.H., H.T.) and Center for Physiology and Pharmacology (W.S.), Medical University of Vienna, Vienna, Austria
| | - Xaver Koenig
- Center for Physiology and Pharmacology, Department of Neurophysiology and Neuropharmacology (V.S.G., P.L., R.C., X.K., L.R., K.H., H.T.) and Center for Physiology and Pharmacology (W.S.), Medical University of Vienna, Vienna, Austria
| | - Lena Rubi
- Center for Physiology and Pharmacology, Department of Neurophysiology and Neuropharmacology (V.S.G., P.L., R.C., X.K., L.R., K.H., H.T.) and Center for Physiology and Pharmacology (W.S.), Medical University of Vienna, Vienna, Austria
| | - Karlheinz Hilber
- Center for Physiology and Pharmacology, Department of Neurophysiology and Neuropharmacology (V.S.G., P.L., R.C., X.K., L.R., K.H., H.T.) and Center for Physiology and Pharmacology (W.S.), Medical University of Vienna, Vienna, Austria
| | - Walter Sandtner
- Center for Physiology and Pharmacology, Department of Neurophysiology and Neuropharmacology (V.S.G., P.L., R.C., X.K., L.R., K.H., H.T.) and Center for Physiology and Pharmacology (W.S.), Medical University of Vienna, Vienna, Austria
| | - Hannes Todt
- Center for Physiology and Pharmacology, Department of Neurophysiology and Neuropharmacology (V.S.G., P.L., R.C., X.K., L.R., K.H., H.T.) and Center for Physiology and Pharmacology (W.S.), Medical University of Vienna, Vienna, Austria
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29
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Arnold WD, Feldman DH, Ramirez S, He L, Kassar D, Quick A, Klassen TL, Lara M, Nguyen J, Kissel JT, Lossin C, Maselli RA. Defective fast inactivation recovery of Nav 1.4 in congenital myasthenic syndrome. Ann Neurol 2015; 77:840-50. [PMID: 25707578 DOI: 10.1002/ana.24389] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2014] [Revised: 02/10/2015] [Accepted: 02/11/2015] [Indexed: 11/06/2022]
Abstract
OBJECTIVE To describe the unique phenotype and genetic findings in a 57-year-old female with a rare form of congenital myasthenic syndrome (CMS) associated with longstanding muscle fatigability, and to investigate the underlying pathophysiology. METHODS We used whole-cell voltage clamping to compare the biophysical parameters of wild-type and Arg1457His-mutant Nav 1.4. RESULTS Clinical and neurophysiological evaluation revealed features consistent with CMS. Sequencing of candidate genes indicated no abnormalities. However, analysis of SCN4A, the gene encoding the skeletal muscle sodium channel Nav 1.4, revealed a homozygous mutation predicting an arginine-to-histidine substitution at position 1457 (Arg1457His), which maps to the channel's voltage sensor, specifically D4/S4. Whole-cell patch clamp studies revealed that the mutant required longer hyperpolarization to recover from fast inactivation, which produced a profound use-dependent current attenuation not seen in the wild type. The mutant channel also had a marked hyperpolarizing shift in its voltage dependence of inactivation as well as slowed inactivation kinetics. INTERPRETATION We conclude that Arg1457His compromises muscle fiber excitability. The mutant fast-inactivates with significantly less depolarization, and it recovers only after extended hyperpolarization. The resulting enhancement in its use dependence reduces channel availability, which explains the patient's muscle fatigability. Arg1457His offers molecular insight into a rare form of CMS precipitated by sodium channel inactivation defects. Given this channel's involvement in other muscle disorders such as paramyotonia congenita and hyperkalemic periodic paralysis, our study exemplifies how variations within the same gene can give rise to multiple distinct dysfunctions and phenotypes, revealing residues important in basic channel function.
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Affiliation(s)
- W David Arnold
- Department of Neurology, Ohio State University Wexner Medical Center, Columbus, OH
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Li J, Huang Q, Ge L, Xu J, Shi X, Xie W, Liu X, Liu X. Identification of genetic variations of a Chinese family with paramyotonia congenita via whole exome sequencing. GENOMICS DATA 2015; 4:65-8. [PMID: 26484179 PMCID: PMC4535863 DOI: 10.1016/j.gdata.2015.03.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/06/2015] [Revised: 03/03/2015] [Accepted: 03/03/2015] [Indexed: 11/09/2022]
Abstract
Paramyotonia congenita (PC) is a rare autosomal dominant neuromuscular disorder characterized by juvenile onset and development of cold-induced myotonia after repeated activities. The disease is mostly caused by genetic mutations of the sodium channel, voltage-gated, type IV, alpha subunit (SCN4A) gene. This study intended to systematically identify the causative genetic variations of a Chinese Han PC family. Seven members of this PC family, including four patients and three healthy controls, were selected for whole exome sequencing (WES) using the Illumina HiSeq platform. Sequence variations were identified using the SoftGenetics program. The mutation R1448C of SCN4A was found to be the only causative mutation. This study applied WES technology to sequence multiple members of a large PC family and was the first to systematically confirm that the genetic change in SCN4A is the only causative variation in this PC family and the SCN4A mutation is sufficient to lead to PC.
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Affiliation(s)
- Jinxin Li
- Key Laboratory of Developmental Genes and Human Diseases, Institute of Life Sciences, Southeast University, Nanjing 210096, China
| | - Qinghai Huang
- Key Laboratory of Developmental Genes and Human Diseases, Institute of Life Sciences, Southeast University, Nanjing 210096, China
| | - Liang Ge
- Key Laboratory of Developmental Genes and Human Diseases, Institute of Life Sciences, Southeast University, Nanjing 210096, China
| | - Jing Xu
- Key Laboratory of Developmental Genes and Human Diseases, Institute of Life Sciences, Southeast University, Nanjing 210096, China
| | - Xingjuan Shi
- Key Laboratory of Developmental Genes and Human Diseases, Institute of Life Sciences, Southeast University, Nanjing 210096, China
| | - Wei Xie
- Key Laboratory of Developmental Genes and Human Diseases, Institute of Life Sciences, Southeast University, Nanjing 210096, China
| | - Xiang Liu
- Hainan Medical University, Hainan 571199, China
| | - Xiangdong Liu
- Key Laboratory of Developmental Genes and Human Diseases, Institute of Life Sciences, Southeast University, Nanjing 210096, China
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31
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The specificity of Av3 sea anemone toxin for arthropods is determined at linker DI/SS2-S6 in the pore module of target sodium channels. Biochem J 2014; 463:271-7. [PMID: 25055135 DOI: 10.1042/bj20140576] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Av3 is a peptide neurotoxin from the sea anemone Anemonia viridis that shows specificity for arthropod voltage-gated sodium channels (Navs). Interestingly, Av3 competes with a scorpion α-toxin on binding to insect Navs and similarly inhibits the inactivation process, and thus has been classified as 'receptor site-3 toxin', although the two peptides are structurally unrelated. This raises questions as to commonalities and differences in the way both toxins interact with Navs. Recently, site-3 was partly resolved for scorpion α-toxins highlighting S1-S2 and S3-S4 external linkers at the DIV voltage-sensor module and the juxtaposed external linkers at the DI pore module. To uncover channel determinants involved in Av3 specificity for arthropods, the toxin was examined on channel chimaeras constructed with the external linkers of the mammalian brain Nav1.2a, which is insensitive to Av3, in the background of the Drosophila DmNav1. This approach highlighted the role of linker DI/SS2-S6, adjacent to the channel pore, in determining Av3 specificity. Point mutagenesis at DI/SS2-S6 accompanied by functional assays highlighted Trp404 and His405 as a putative point of Av3 interaction with DmNav1. His405 conservation in arthropod Navs compared with tyrosine in vertebrate Navs may represent an ancient substitution that explains the contemporary selectivity of Av3. Trp404 and His405 localization near the membrane surface and the hydrophobic bioactive surface of Av3 suggest that the toxin possibly binds at a cleft by DI/S6. A partial overlap in receptor site-3 of both toxins nearby DI/S6 may explain their binding competition capabilities.
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Abstract
Resurgent Na(+) current results from a distinctive form of Na(+) channel gating, originally identified in cerebellar Purkinje neurons. In these neurons, the tetrodotoxin-sensitive voltage-gated Na(+) channels responsible for action potential firing have specialized mechanisms that reduce the likelihood that they accumulate in fast inactivated states, thereby shortening refractory periods and permitting rapid, repetitive, and/or burst firing. Under voltage clamp, step depolarizations evoke transient Na(+) currents that rapidly activate and quickly decay, and step repolarizations elicit slower channel reopening, or a 'resurgent' current. The generation of resurgent current depends on a factor in the Na(+) channel complex, probably a subunit such as NaVβ4 (Scn4b), which blocks open Na(+) channels at positive voltages, competing with the fast inactivation gate, and unblocks at negative voltages, permitting recovery from an open channel block along with a flow of current. Following its initial discovery, resurgent Na(+) current has been found in nearly 20 types of neurons. Emerging research suggests that resurgent current is preferentially increased in a variety of clinical conditions associated with altered cellular excitability. Here we review the biophysical, molecular and structural mechanisms of resurgent current and their relation to the normal functions of excitable cells as well as pathophysiology.
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Affiliation(s)
- Amanda H Lewis
- Ion Channel Research Unit & Department of Neurobiology, Duke University Medical Center, Durham, NC, 27710, USA
| | - Indira M Raman
- Department of Neurobiology, Northwestern University, Evanston, IL, 60208, USA
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Brunklaus A, Ellis R, Reavey E, Semsarian C, Zuberi SM. Genotype phenotype associations across the voltage-gated sodium channel family. J Med Genet 2014; 51:650-8. [PMID: 25163687 DOI: 10.1136/jmedgenet-2014-102608] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Mutations in genes encoding voltage-gated sodium channels have emerged as the most clinically relevant genes associated with epilepsy, cardiac conduction defects, skeletal muscle channelopathies and peripheral pain disorders. Geneticists in partnership with neurologists and cardiologists are often asked to comment on the clinical significance of specific mutations. We have reviewed the evidence relating to genotype phenotype associations among the best known voltage-gated sodium channel related disorders. Comparing over 1300 sodium channel mutations in central and peripheral nervous system, heart and muscle, we have identified many similarities in the genetic and clinical characteristics across the voltage-gated sodium channel family. There is evidence, that the level of impairment a specific mutation causes can be anticipated by the underlying physico-chemical property change of that mutation. Across missense mutations those with higher Grantham scores are associated with more severe phenotypes and truncating mutations underlie the most severe phenotypes. Missense mutations are clustered in specific areas and are associated with distinct phenotypes according to their position in the protein. Inherited mutations tend to be less severe than de novo mutations which are usually associated with greater physico-chemical difference. These findings should lead to a better understanding of the clinical significance of specific voltage-gated sodium channel mutations, aiding geneticists and physicians in the interpretation of genetic variants and counselling individuals and their families.
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Affiliation(s)
- Andreas Brunklaus
- The Paediatric Neurosciences Research Group, Royal Hospital for Sick Children, Glasgow, UK
| | - Rachael Ellis
- The Paediatric Neurosciences Research Group, Royal Hospital for Sick Children, Glasgow, UK Molecular Diagnostics, West of Scotland Genetic Services, Southern General Hospital, Glasgow, UK
| | - Eleanor Reavey
- The Paediatric Neurosciences Research Group, Royal Hospital for Sick Children, Glasgow, UK Molecular Diagnostics, West of Scotland Genetic Services, Southern General Hospital, Glasgow, UK
| | - Christopher Semsarian
- Agnes Ginges Centre for Molecular Cardiology, Centenary Institute, Sydney, Australia Sydney Medical School, University of Sydney, Australia
| | - Sameer M Zuberi
- The Paediatric Neurosciences Research Group, Royal Hospital for Sick Children, Glasgow, UK School of Medicine, College of Medical, Veterinary & Life Sciences, University of Glasgow, UK
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34
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Moreau A, Gosselin-Badaroudine P, Chahine M. Biophysics, pathophysiology, and pharmacology of ion channel gating pores. Front Pharmacol 2014; 5:53. [PMID: 24772081 PMCID: PMC3982104 DOI: 10.3389/fphar.2014.00053] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2014] [Accepted: 03/12/2014] [Indexed: 12/19/2022] Open
Abstract
Voltage sensor domains (VSDs) are a feature of voltage gated ion channels (VGICs) and voltage sensitive proteins. They are composed of four transmembrane (TM) segments (S1–S4). Currents leaking through VSDs are called omega or gating pore currents. Gating pores are caused by mutations of the highly conserved positively charged amino acids in the S4 segment that disrupt interactions between the S4 segment and the gating charge transfer center (GCTC). The GCTC separates the intracellular and extracellular water crevices. The disruption of S4–GCTC interactions allows these crevices to communicate and create a fast activating and non-inactivating alternative cation-selective permeation pathway of low conductance, or a gating pore. Gating pore currents have recently been shown to cause periodic paralysis phenotypes. There is also increasing evidence that gating pores are linked to several other familial diseases. For example, gating pores in Nav1.5 and Kv7.2 channels may underlie mixed arrhythmias associated with dilated cardiomyopathy (DCM) phenotypes and peripheral nerve hyperexcitability (PNH), respectively. There is little evidence for the existence of gating pore blockers. Moreover, it is known that a number of toxins bind to the VSD of a specific domain of Na+ channels. These toxins may thus modulate gating pore currents. This focus on the VSD motif opens up a new area of research centered on developing molecules to treat a number of cell excitability disorders such as epilepsy, cardiac arrhythmias, and pain. The purpose of the present review is to summarize existing knowledge of the pathophysiology, biophysics, and pharmacology of gating pore currents and to serve as a guide for future studies aimed at improving our understanding of gating pores and their pathophysiological roles.
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Affiliation(s)
- Adrien Moreau
- Centre de Recherche de L'Institut Universitaire en Santé Mentale de Québec Quebec City, QC, Canada
| | | | - Mohamed Chahine
- Centre de Recherche de L'Institut Universitaire en Santé Mentale de Québec Quebec City, QC, Canada ; Department of Medicine, Université Laval Quebec City, QC, Canada
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35
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Gao R, Du Y, Wang L, Nomura Y, Satar G, Gordon D, Gurevitz M, Goldin AL, Dong K. Sequence variations at I260 and A1731 contribute to persistent currents in Drosophila sodium channels. Neuroscience 2014; 268:297-308. [PMID: 24662849 DOI: 10.1016/j.neuroscience.2014.03.028] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2013] [Revised: 02/02/2014] [Accepted: 03/09/2014] [Indexed: 12/19/2022]
Abstract
Tetrodotoxin-sensitive persistent sodium currents, INaP, that activate at subthreshold voltages, have been detected in numerous vertebrate and invertebrate neurons. These currents are believed to be critical for regulating neuronal excitability. However, the molecular mechanism underlying INaP is controversial. In this study, we identified an INaP with a broad range of voltage dependence, from -60mV to 20mV, in a Drosophila sodium channel variant expressed in Xenopus oocytes. Mutational analysis revealed that two variant-specific amino acid changes, I260T in the S4-S5 linker of domain I (ILS4-S5) and A1731V in the voltage sensor S4 of domain IV (IVS4), contribute to the INaP. I260T is critical for the portion of INaP at hyperpolarized potentials. The T260-mediated INaP is likely the result of window currents flowing in the voltage range where the activation and inactivation curves overlap. A1731V is responsible for impaired inactivation and contributes to the portion of INaP at depolarized potentials. Furthermore, A1731V causes enhanced activity of two site-3 toxins which induce persistent currents by inhibiting the outward movement of IVS4, suggesting that A1731V inhibits the outward movement of IVS4. These results provided molecular evidence for the involvement of distinct mechanisms in the generation of INaP: T260 contributes to INaP via enhancement of the window current, whereas V1731 impairs fast inactivation probably by inhibiting the outward movement of IVS4.
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Affiliation(s)
- R Gao
- Department of Entomology and Neuroscience Program, Michigan State University, East Lansing, MI 48824, United States
| | - Y Du
- Department of Entomology and Neuroscience Program, Michigan State University, East Lansing, MI 48824, United States
| | - L Wang
- Department of Entomology and Neuroscience Program, Michigan State University, East Lansing, MI 48824, United States
| | - Y Nomura
- Department of Entomology and Neuroscience Program, Michigan State University, East Lansing, MI 48824, United States
| | - G Satar
- Department of Entomology and Neuroscience Program, Michigan State University, East Lansing, MI 48824, United States
| | - D Gordon
- Department of Plant Molecular Biology & Ecology, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Israel
| | - M Gurevitz
- Department of Plant Molecular Biology & Ecology, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Israel
| | - A L Goldin
- Department of Microbiology and Molecular Genetics, University of California, Irvine, CA 92697, United States
| | - K Dong
- Department of Entomology and Neuroscience Program, Michigan State University, East Lansing, MI 48824, United States.
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36
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Abstract
The mechanism by which voltage-gated ion channels respond to changes in membrane polarization during action potential signaling in excitable cells has been the subject of research attention since the original description of voltage-dependent sodium and potassium flux in the squid giant axon. The cloning of ion channel genes and the identification of point mutations associated with channelopathy diseases in muscle and brain has facilitated an electrophysiological approach to the study of ion channels. Experimental approaches to the study of voltage gating have incorporated the use of thiosulfonate reagents to test accessibility, fluorescent probes, and toxins to define domain-specific roles of voltage-sensing S4 segments. Crystallography, structural and homology modeling, and molecular dynamics simulations have added computational approaches to study the relationship of channel structure to function. These approaches have tested models of voltage sensor translocation in response to membrane depolarization and incorporate the role of negative countercharges in the S1 to S3 segments to define our present understanding of the mechanism by which the voltage sensor module dictates gating particle permissiveness in excitable cells.
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Affiliation(s)
- James R Groome
- Department of Biological Sciences, Idaho State University, Pocatello, ID, 83209, USA,
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37
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Goldschen-Ohm MP, Chanda B. Probing gating mechanisms of sodium channels using pore blockers. Handb Exp Pharmacol 2014; 221:183-201. [PMID: 24737237 DOI: 10.1007/978-3-642-41588-3_9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Several classes of small molecules and peptides bind at the central pore of voltage-gated sodium channels either from the extracellular or intracellular side of the membrane and block ion conduction through the pore. Biophysical studies that shed light on the chemical nature, accessibility, and kinetics of binding of these naturally occurring and synthetic compounds reveal a wealth of information about how these channels gate. Here, we discuss insights into the structural underpinnings of gating of the channel pore and its coupling to the voltage sensors obtained from pore blockers including site 1 neurotoxins and local anesthetics.
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38
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Ma Z, Kong J, Gordon D, Gurevitz M, Kallen RG. Direct evidence that scorpion α-toxins (site-3) modulate sodium channel inactivation by hindrance of voltage-sensor movements. PLoS One 2013; 8:e77758. [PMID: 24302985 PMCID: PMC3841157 DOI: 10.1371/journal.pone.0077758] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2013] [Accepted: 09/07/2013] [Indexed: 01/09/2023] Open
Abstract
The position of the voltage-sensing transmembrane segment, S4, in voltage-gated ion channels as a function of voltage remains incompletely elucidated. Site-3 toxins bind primarily to the extracellular loops connecting transmembrane helical segments S1-S2 and S3-S4 in Domain 4 (D4) and S5-S6 in Domain 1 (D1) and slow fast-inactivation of voltage-gated sodium channels. As S4 of the human skeletal muscle voltage-gated sodium channel, hNav1.4, moves in response to depolarization from the resting to the inactivated state, two D4S4 reporters (R2C and R3C, Arg1451Cys and Arg1454Cys, respectively) move from internal to external positions as deduced by reactivity to internally or externally applied sulfhydryl group reagents, methane thiosulfonates (MTS). The changes in reporter reactivity, when cycling rapidly between hyperpolarized and depolarized voltages, enabled determination of the positions of the D4 voltage-sensor and of its rate of movement. Scorpion α-toxin binding impedes D4S4 segment movement during inactivation since the modification rates of R3C in hNav1.4 with methanethiosulfonate (CH3SO2SCH2CH2R, where R = -N(CH3)3 (+) trimethylammonium, MTSET) and benzophenone-4-carboxamidocysteine methanethiosulfonate (BPMTS) were slowed ~10-fold in toxin-modified channels. Based upon the different size, hydrophobicity and charge of the two reagents it is unlikely that the change in reactivity is due to direct or indirect blockage of access of this site to reagent in the presence of toxin (Tx), but rather is the result of inability of this segment to move outward to the normal extent and at the normal rate in the toxin-modified channel. Measurements of availability of R3C to internally applied reagent show decreased access (slower rates of thiol reaction) providing further evidence for encumbered D4S4 movement in the presence of toxins consistent with the assignment of at least part of the toxin binding site to the region of D4S4 region of the voltage-sensor module.
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Affiliation(s)
- Zhongming Ma
- Department of Biochemistry and Biophysics, Perelman School of Medicine University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Jun Kong
- Department of Biochemistry and Biophysics, Perelman School of Medicine University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Dalia Gordon
- Department of Plant Molecular Biology and Ecology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Ramat Aviv, Tel Aviv, Israel
| | - Michael Gurevitz
- Department of Plant Molecular Biology and Ecology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Ramat Aviv, Tel Aviv, Israel
| | - Roland G. Kallen
- Department of Biochemistry and Biophysics, Perelman School of Medicine University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- The Mahoney Institute for Neuroscience, Perelman School of Medicine University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
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39
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Sheets MF, Chen T, Hanck DA. Outward stabilization of the voltage sensor in domain II but not domain I speeds inactivation of voltage-gated sodium channels. Am J Physiol Heart Circ Physiol 2013; 305:H1213-21. [DOI: 10.1152/ajpheart.00225.2013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
To determine the roles of the individual S4 segments in domains I and II to activation and inactivation kinetics of sodium current ( INa) in NaV1.5, we used a tethered biotin and avidin approach after a site-directed cysteine substitution was made in the second outermost Arg in each S4 (DI-R2C and DII-R2C). We first determined the fraction of gating charge contributed by the individual S4's to maximal gating current (Qmax), and found that the outermost Arg residue in each S4 contributed ∼19% to Qmax with minimal contributions by other arginines. Stabilization of the S4's in DI-R2C and DII-R2C was confirmed by measuring the expected reduction in Qmax. In DI-R2C, stabilization resulted in a decrease in peak INa of ∼45%, while its peak current-voltage ( I-V) and voltage-dependent Na channel availability (SSI) curves were nearly unchanged from wild type (WT). In contrast, stabilization of the DII-R2C enhanced activation with a negative shift in the peak I-V relationship by −7 mV and a larger −17 mV shift in the voltage-dependent SSI curve. Furthermore, its INa decay time constants and time-to-peak INa became more rapid than WT. An explanation for these results is that the depolarized conformation of DII-S4, but not DI-S4, affects the receptor for the inactivation particle formed by the interdomain linker between DIII and IV. In addition, the leftward shifts of both activation and inactivation and the decrease in Gmax after stabilization of the DII-S4 support previous studies that showed β-scorpion toxins trap the voltage sensor of DII in an activated conformation.
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Affiliation(s)
- Michael F. Sheets
- The Nora Eccles Harrison Cardiovascular Research and Training Institute and the Department of Internal Medicine, University of Utah, Salt Lake City, Utah; and
| | - Tiehua Chen
- The Nora Eccles Harrison Cardiovascular Research and Training Institute and the Department of Internal Medicine, University of Utah, Salt Lake City, Utah; and
| | - Dorothy A. Hanck
- The Department of Medicine, The University of Chicago, Chicago, Illinois
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40
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Lewis AH, Raman IM. Interactions among DIV voltage-sensor movement, fast inactivation, and resurgent Na current induced by the NaVβ4 open-channel blocking peptide. ACTA ACUST UNITED AC 2013; 142:191-206. [PMID: 23940261 PMCID: PMC3753608 DOI: 10.1085/jgp.201310984] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Resurgent Na current flows as voltage-gated Na channels recover through open states from block by an endogenous open-channel blocking protein, such as the NaVβ4 subunit. The open-channel blocker and fast-inactivation gate apparently compete directly, as slowing the onset of fast inactivation increases resurgent currents by favoring binding of the blocker. Here, we tested whether open-channel block is also sensitive to deployment of the DIV voltage sensor, which facilitates fast inactivation. We expressed NaV1.4 channels in HEK293t cells and assessed block by a free peptide replicating the cytoplasmic tail of NaVβ4 (the "β4 peptide"). Macroscopic fast inactivation was disrupted by mutations of DIS6 (L443C/A444W; "CW" channels), which reduce fast-inactivation gate binding, and/or by the site-3 toxin ATX-II, which interferes with DIV movement. In wild-type channels, the β4 peptide competed poorly with fast inactivation, but block was enhanced by ATX. With the CW mutation, large peptide-induced resurgent currents were present even without ATX, consistent with increased open-channel block upon depolarization and slower deactivation after blocker unbinding upon repolarization. The addition of ATX greatly increased transient current amplitudes and further enlarged resurgent currents, suggesting that pore access by the blocker is actually decreased by full deployment of the DIV voltage sensor. ATX accelerated recovery from block at hyperpolarized potentials, however, suggesting that the peptide unbinds more readily when DIV voltage-sensor deployment is disrupted. These results are consistent with two open states in Na channels, dependent on the DIV voltage-sensor position, which differ in affinity for the blocking protein.
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Affiliation(s)
- Amanda H Lewis
- Interdepartmental Biological Sciences Program and 2 Department of Neurobiology, Northwestern University, Evanston, IL 60208, USA
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41
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Capes DL, Goldschen-Ohm MP, Arcisio-Miranda M, Bezanilla F, Chanda B. Domain IV voltage-sensor movement is both sufficient and rate limiting for fast inactivation in sodium channels. ACTA ACUST UNITED AC 2013; 142:101-12. [PMID: 23858005 PMCID: PMC3727307 DOI: 10.1085/jgp.201310998] [Citation(s) in RCA: 147] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Voltage-gated sodium channels are critical for the generation and propagation of electrical signals in most excitable cells. Activation of Na(+) channels initiates an action potential, and fast inactivation facilitates repolarization of the membrane by the outward K(+) current. Fast inactivation is also the main determinant of the refractory period between successive electrical impulses. Although the voltage sensor of domain IV (DIV) has been implicated in fast inactivation, it remains unclear whether the activation of DIV alone is sufficient for fast inactivation to occur. Here, we functionally neutralize each specific voltage sensor by mutating several critical arginines in the S4 segment to glutamines. We assess the individual role of each voltage-sensing domain in the voltage dependence and kinetics of fast inactivation upon its specific inhibition. We show that movement of the DIV voltage sensor is the rate-limiting step for both development and recovery from fast inactivation. Our data suggest that activation of the DIV voltage sensor alone is sufficient for fast inactivation to occur, and that activation of DIV before channel opening is the molecular mechanism for closed-state inactivation. We propose a kinetic model of sodium channel gating that can account for our major findings over a wide voltage range by postulating that DIV movement is both necessary and sufficient for fast inactivation.
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Affiliation(s)
- Deborah L Capes
- Department of Neuroscience, University of Wisconsin, Madison, Madison, WI 53706, USA
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42
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Affiliation(s)
- Christopher A Ahern
- Department of Molecular Physiology and Biophysics, The University of Iowa, Iowa City, IA 52242, USA
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43
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Multiple pore conformations driven by asynchronous movements of voltage sensors in a eukaryotic sodium channel. Nat Commun 2013; 4:1350. [PMID: 23322038 PMCID: PMC3562458 DOI: 10.1038/ncomms2356] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2012] [Accepted: 12/04/2012] [Indexed: 11/08/2022] Open
Abstract
Voltage-dependent Na(+) channels are crucial for electrical signalling in excitable cells. Membrane depolarization initiates asynchronous movements in four non-identical voltage-sensing domains of the Na(+) channel. It remains unclear to what extent this structural asymmetry influences pore gating as compared with outwardly rectifying K(+) channels, where channel opening results from a final concerted transition of symmetric pore gates. Here we combine single channel recordings, cysteine accessibility and voltage clamp fluorimetry to probe the relationships between voltage sensors and pore conformations in an inactivation deficient Nav1.4 channel. We observe three distinct conductance levels such that DI-III voltage sensor activation is kinetically correlated with formation of a fully open pore, whereas DIV voltage sensor movement underlies formation of a distinct subconducting pore conformation preceding inactivation in wild-type channels. Our experiments reveal that pore gating in sodium channels involves multiple transitions driven by asynchronous movements of voltage sensors. These findings shed new light on the mechanism of coupling between activation and fast inactivation in voltage-gated sodium channels.
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44
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Frossard B, Combret C, Benhamou D. [Analgesia for labour and delivery in a parturient with paramytonia congenita]. ACTA ACUST UNITED AC 2013; 32:372-4. [PMID: 23648013 DOI: 10.1016/j.annfar.2013.03.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2013] [Accepted: 03/25/2013] [Indexed: 11/15/2022]
Abstract
A patient presenting with paramyotonia congenita (Eulenburg's paramyotonia) was seen at the preanaesthetic visit during pregnancy. The underlying disease was known for years. Analysis of the literature and advice taken from specialists emphasized the safe use of regional anaesthesia and analgesia which was indeed used for labour and delivery without any complication. By contrast, the limited information available on the use of general anaesthesia suggests the risks associated with the use of succinylcholine and possibly with halogenated agents. Additional and useful factors that may limit the occurrence of myotonic crises such as maintenance of normal temperature and plasma potassium concentration, should be undertaken simultaneously.
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Affiliation(s)
- B Frossard
- Département d'anesthésie-réanimation, hôpital Bicêtre, hôpitaux universitaires Paris-Sud, 78 rue du Général-Leclerc, Le Kremlin-Bicêtre cedex, France
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45
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Groome JR, Winston V. S1-S3 counter charges in the voltage sensor module of a mammalian sodium channel regulate fast inactivation. ACTA ACUST UNITED AC 2013; 141:601-18. [PMID: 23589580 PMCID: PMC3639575 DOI: 10.1085/jgp.201210935] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The movement of positively charged S4 segments through the electric field drives the voltage-dependent gating of ion channels. Studies of prokaryotic sodium channels provide a mechanistic view of activation facilitated by electrostatic interactions of negatively charged residues in S1 and S2 segments, with positive counterparts in the S4 segment. In mammalian sodium channels, S4 segments promote domain-specific functions that include activation and several forms of inactivation. We tested the idea that S1-S3 countercharges regulate eukaryotic sodium channel functions, including fast inactivation. Using structural data provided by bacterial channels, we constructed homology models of the S1-S4 voltage sensor module (VSM) for each domain of the mammalian skeletal muscle sodium channel hNaV1.4. These show that side chains of putative countercharges in hNaV1.4 are oriented toward the positive charge complement of S4. We used mutagenesis to define the roles of conserved residues in the extracellular negative charge cluster (ENC), hydrophobic charge region (HCR), and intracellular negative charge cluster (INC). Activation was inhibited with charge-reversing VSM mutations in domains I-III. Charge reversal of ENC residues in domains III (E1051R, D1069K) and IV (E1373K, N1389K) destabilized fast inactivation by decreasing its probability, slowing entry, and accelerating recovery. Several INC mutations increased inactivation from closed states and slowed recovery. Our results extend the functional characterization of VSM countercharges to fast inactivation, and support the premise that these residues play a critical role in domain-specific gating transitions for a mammalian sodium channel.
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Affiliation(s)
- James R Groome
- Department of Biological Sciences, Idaho State University, Pocatello, ID 83209, USA.
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46
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Gating pore currents and the resting state of Nav1.4 voltage sensor domains. Proc Natl Acad Sci U S A 2012; 109:19250-5. [PMID: 23134726 DOI: 10.1073/pnas.1217990109] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Mammalian voltage-gated sodium channels are composed of four homologous voltage sensor domains (VSDs; DI, DII, DIII, and DIV) in which their S4 segments contain a variable number of positively charged residues. We used single histidine (H) substitutions of these charged residues in the Na(v)1.4 channel to probe the positions of the S4 segments at hyperpolarized potentials. The substitutions led to the formation of gating pores that were detected as proton leak currents through the VSDs. The leak currents indicated that the mutated residues are accessible from both sides of the membrane. Leak currents of different magnitudes appeared in the DI/R1H, DII/R1H, and DIII/R2H mutants, suggesting that the resting state position of S4 varies depending on the domain. Here, DI/R1H indicates the first arginine R1, in domain DI, has been mutated to histidine. The single R1H, R2H, and R3H mutations in DIV did not produce appreciable proton currents, indicating that the VSDs had different topologies. A structural model of the resting states of the four VSDs of Na(v)1.4 relaxed in their membrane/solution environment using molecular dynamics simulations is proposed based on the recent Na(v)Ab sodium channel X-ray structure. The model shows that the hydrophobic septa that isolate the intracellular and the extracellular media within the DI, DII, and DIII VSDs are ∼2 Å long, similar to those of K(v) channels. However, the septum of DIV is longer, which prevents water molecules from hydrating the center of the VSD, thus breaking the proton conduction pathway. This structural model rationalizes the activation sequence of the different VSDs of the Na(v)1.4 channel.
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47
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Nurputra DK, Nakagawa T, Takeshima Y, Harahap ISK, Morikawa S, Sakaeda T, Lai PS, Matsuo M, Takaoka Y, Nishio H. Paramyotonia congenita: from clinical diagnosis to in silico protein modeling analysis. Pediatr Int 2012; 54:602-12. [PMID: 22507243 DOI: 10.1111/j.1442-200x.2012.03646.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
BACKGROUND Paramyotonia congenita (PMC) is an autosomal dominant disorder characterized by cold- or exercise-induced myotonia. PMC is caused by a mutation in SCN4A which encodes the α-subunit of the skeletal muscle sodium channel. METHODS The patient was an 11-year-old Japanese girl who was diagnosed as having PMC. To confirm the diagnosis, an orbital ice-pack test and blinking tests were performed. Next, to identify the mutation, genetic analysis of SCN4A was performed. Finally, to evaluate the mutation effect on the protein structure, in silico protein modeling analysis was performed. RESULTS Cold- and exercise-induced myotonia was reproduced in the patient with non-invasive bedside tests: ice-pack and blinking tests. In the genetic analysis, a missense mutation, c.4343G>A in SCN4A, was identified, which may result in an arginine to histidine substitution at 1448 in the protein sequence (p.Arg1448His). According to the protein modeling analysis, the mutation neutralized the positive electrostatic charge at 1448 in the DIV/S4 segment and disrupted the beginning of the helical structure in the DIV/S3-S4 linker of the SCN4A protein. CONCLUSIONS Diagnostic physical interventions in the patient confirmed the phenotype presentation consistent with PMC, and the in silico protein modeling analysis of p.Arg1448His predicted structural changes which can affect function of the protein. All the data confirmed the diagnosis of PMC in the patient and added to existing literature emphasizing the important role of arginine residue at 1448.
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Affiliation(s)
- Dian K Nurputra
- Department of Community Medicine and Social Health Care, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-Cho, Chuo-Ku, Kobe 650-0017, Japan
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48
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Paldi T. Enhancement of Closed-State Inactivation by Neutralization of S4 Arginines in Domain IV of a Sodium Channel. Front Pharmacol 2012; 3:143. [PMID: 22826699 PMCID: PMC3399128 DOI: 10.3389/fphar.2012.00143] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2012] [Accepted: 07/03/2012] [Indexed: 11/21/2022] Open
Affiliation(s)
- Tzur Paldi
- The Hebrew University of Jerusalem Jerusalem, Israel
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49
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Goldfarb M. Voltage-gated sodium channel-associated proteins and alternative mechanisms of inactivation and block. Cell Mol Life Sci 2012; 69:1067-76. [PMID: 21947499 PMCID: PMC3272111 DOI: 10.1007/s00018-011-0832-1] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2011] [Revised: 09/11/2011] [Accepted: 09/13/2011] [Indexed: 12/13/2022]
Abstract
Voltage-gated sodium channels mediate inward current of action potentials upon membrane depolarization of excitable cells. The initial transient sodium current is restricted to milliseconds through three distinct channel-inactivating and blocking mechanisms. All pore-forming alpha subunits of sodium channels possess structural elements mediating fast inactivation upon depolarization and recovery within milliseconds upon membrane repolarization. Accessory subunits modulate fast inactivation dynamics, but these proteins can also limit current by contributing distinct inactivation and blocking particles. A-type isoforms of fibroblast growth factor homologous factors (FHFs) bear a particle that induces long-term channel inactivation, while sodium channel subunit Navβ4 employs a blocking particle that rapidly dissociates upon membrane repolarization to generate resurgent current. Despite their different physiological functions, the FHF and Navβ4 particles have similarity in amino acid composition and mechanisms for docking within sodium channels. The three competing channel-inactivating and blocking processes functionally interact to regulate a neuron's intrinsic excitability.
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Affiliation(s)
- Mitchell Goldfarb
- Department of Biological Sciences, Hunter College of City University, New York, NY, 10065, USA.
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50
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Gonzalez C, Contreras GF, Peyser A, Larsson P, Neely A, Latorre R. Voltage sensor of ion channels and enzymes. Biophys Rev 2012; 4:1-15. [PMID: 28509999 PMCID: PMC5425699 DOI: 10.1007/s12551-011-0061-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2011] [Accepted: 11/17/2011] [Indexed: 10/14/2022] Open
Abstract
Placed in the cell membrane (a two-dimensional environment), ion channels and enzymes are able to sense voltage. How these proteins are able to detect the difference in the voltage across membranes has attracted much attention, and at times, heated debate during the last few years. Sodium, Ca2+ and K+ voltage-dependent channels have a conserved positively charged transmembrane (S4) segment that moves in response to changes in membrane voltage. In voltage-dependent channels, S4 forms part of a domain that crystallizes as a well-defined structure consisting of the first four transmembrane (S1-S4) segments of the channel-forming protein, which is defined as the voltage sensor domain (VSD). The VSD is tied to a pore domain and VSD movements are allosterically coupled to the pore opening to various degrees, depending on the type of channel. How many charges are moved during channel activation, how much they move, and which are the molecular determinants that mediate the electromechanical coupling between the VSD and the pore domains are some of the questions that we discuss here. The VSD can function, however, as a bona fide proton channel itself, and, furthermore, the VSD can also be a functional part of a voltage-dependent phosphatase.
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Affiliation(s)
- Carlos Gonzalez
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Pasaje Harrington 287, Valparaíso, 2360103, Chile
| | - Gustavo F Contreras
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Pasaje Harrington 287, Valparaíso, 2360103, Chile
| | - Alexander Peyser
- Department of Physiology and Biophysics, University of Miami, Miami, FL, USA
| | - Peter Larsson
- Department of Physiology and Biophysics, University of Miami, Miami, FL, USA
| | - Alan Neely
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Pasaje Harrington 287, Valparaíso, 2360103, Chile
| | - Ramón Latorre
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Pasaje Harrington 287, Valparaíso, 2360103, Chile.
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