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Tankisi H, Bostock H, Tan SV, Howells J, Ng K, Z'Graggen WJ. Muscle excitability testing. Clin Neurophysiol 2024; 164:1-18. [PMID: 38805900 DOI: 10.1016/j.clinph.2024.04.022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2023] [Revised: 04/22/2024] [Accepted: 04/22/2024] [Indexed: 05/30/2024]
Abstract
Conventional electrophysiological methods, i.e. nerve conduction studies and electromyography are suitable methods for the diagnosis of neuromuscular disorders, however, they provide limited information about muscle fibre membrane properties and underlying disease mechanisms. Muscle excitability testing is a technique that provides in vivo information about muscle fibre membrane properties such as membrane potential and ion channel function. Since the 1960s, various methodologies have been suggested to examine muscle membrane properties but technical difficulties have limited its use. In 2009, an automated, fast and simple application, the so-called multi-fibre muscle velocity recovery cycles (MVRC) has accelerated the use of muscle excitability testing. Later, frequency ramp and repetitive stimulation protocols have been developed. Though this method has been used mainly in research for revealing disease mechanisms across a broad range of neuromuscular disorders, it may have additional diagnostic uses; value has been shown particularly in muscle channelopathies. This review will provide a description of the state-of-the art of methodological and clinical studies for muscle excitability testing.
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Affiliation(s)
- H Tankisi
- Department of Clinical Neurophysiology, Aarhus University Hospital, Aarhus, Denmark; Institute of Clinical Medicine, Aarhus University Hospital, Aarhus, Denmark.
| | - H Bostock
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, Queen Square, WC1N 3BG London, United Kingdom
| | - S V Tan
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, Queen Square, WC1N 3BG London, United Kingdom; Department of Neurology and Neurophysiology, Guys and St Thomas' NHS Foundation Trust, London, United Kingdom
| | - J Howells
- Central Clinical School, Faculty of Medicine and Health, University of Sydney, Sydney, Australia
| | - K Ng
- Department of Neurology and Neurophysiology, Royal North Shore Hospital, St Leonards, NSW, Australia; University of Sydney, Camperdown, NSW, Australia
| | - W J Z'Graggen
- Departments Neurology and Neurosurgery, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
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2
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Sun Y, Xiao Z, Chen B, Zhao Y, Dai J. Advances in Material-Assisted Electromagnetic Neural Stimulation. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024; 36:e2400346. [PMID: 38594598 DOI: 10.1002/adma.202400346] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2024] [Revised: 03/26/2024] [Indexed: 04/11/2024]
Abstract
Bioelectricity plays a crucial role in organisms, being closely connected to neural activity and physiological processes. Disruptions in the nervous system can lead to chaotic ionic currents at the injured site, causing disturbances in the local cellular microenvironment, impairing biological pathways, and resulting in a loss of neural functions. Electromagnetic stimulation has the ability to generate internal currents, which can be utilized to counter tissue damage and aid in the restoration of movement in paralyzed limbs. By incorporating implanted materials, electromagnetic stimulation can be targeted more accurately, thereby significantly improving the effectiveness and safety of such interventions. Currently, there have been significant advancements in the development of numerous promising electromagnetic stimulation strategies with diverse materials. This review provides a comprehensive summary of the fundamental theories, neural stimulation modulating materials, material application strategies, and pre-clinical therapeutic effects associated with electromagnetic stimulation for neural repair. It offers a thorough analysis of current techniques that employ materials to enhance electromagnetic stimulation, as well as potential therapeutic strategies for future applications.
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Affiliation(s)
- Yuting Sun
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and developmental Biology, Chinese Academy of Sciences, Beijing, 100101, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Zhifeng Xiao
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and developmental Biology, Chinese Academy of Sciences, Beijing, 100101, China
| | - Bing Chen
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and developmental Biology, Chinese Academy of Sciences, Beijing, 100101, China
| | - Yannan Zhao
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and developmental Biology, Chinese Academy of Sciences, Beijing, 100101, China
| | - Jianwu Dai
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and developmental Biology, Chinese Academy of Sciences, Beijing, 100101, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
- Tianjin Key Laboratory of Biomedical Materials, Institute of Biomedical Engineering, Chinese Academy of Medical Sciences & Peking Union Medical College, Tianjin, 300192, China
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Renaud JM, Ørtenblad N, McKenna MJ, Overgaard K. Exercise and fatigue: integrating the role of K +, Na + and Cl - in the regulation of sarcolemmal excitability of skeletal muscle. Eur J Appl Physiol 2023; 123:2345-2378. [PMID: 37584745 PMCID: PMC10615939 DOI: 10.1007/s00421-023-05270-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Accepted: 06/29/2023] [Indexed: 08/17/2023]
Abstract
Perturbations in K+ have long been considered a key factor in skeletal muscle fatigue. However, the exercise-induced changes in K+ intra-to-extracellular gradient is by itself insufficiently large to be a major cause for the force decrease during fatigue unless combined to other ion gradient changes such as for Na+. Whilst several studies described K+-induced force depression at high extracellular [K+] ([K+]e), others reported that small increases in [K+]e induced potentiation during submaximal activation frequencies, a finding that has mostly been ignored. There is evidence for decreased Cl- ClC-1 channel activity at muscle activity onset, which may limit K+-induced force depression, and large increases in ClC-1 channel activity during metabolic stress that may enhance K+ induced force depression. The ATP-sensitive K+ channel (KATP channel) is also activated during metabolic stress to lower sarcolemmal excitability. Taking into account all these findings, we propose a revised concept in which K+ has two physiological roles: (1) K+-induced potentiation and (2) K+-induced force depression. During low-moderate intensity muscle contractions, the K+-induced force depression associated with increased [K+]e is prevented by concomitant decreased ClC-1 channel activity, allowing K+-induced potentiation of sub-maximal tetanic contractions to dominate, thereby optimizing muscle performance. When ATP demand exceeds supply, creating metabolic stress, both KATP and ClC-1 channels are activated. KATP channels contribute to force reductions by lowering sarcolemmal generation of action potentials, whilst ClC-1 channel enhances the force-depressing effects of K+, thereby triggering fatigue. The ultimate function of these changes is to preserve the remaining ATP to prevent damaging ATP depletion.
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Affiliation(s)
- Jean-Marc Renaud
- Faculty of Medicine, Department of Cellular and Molecular Medicine, University of Ottawa, 451 Smyth Rd., Ottawa, ON, K1H 8M5, Canada.
| | - Niels Ørtenblad
- Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark
| | - Michael J McKenna
- Institute for Health and Sport, Victoria University, Melbourne, VIC, 8001, Australia
- College of Physical Education, Southwest University, Chongqing, China
- College of Sport Science, Zhuhai College of Science and Technology, Zhuhai, China
| | - Kristian Overgaard
- Exercise Biology, Department of Public Health, Aarhus University, Aarhus, Denmark
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Ke Q, Zhao Y, Li Y, Ye J, Tang S, He F, Ji F, Dai X, Ni J, Li Y, Griggs RC, Cheng X. Clinical comparison and functional study of the L703P: a recurrent mutation in human SCN4A that causes sodium channel myotonia. Neuromuscul Disord 2022; 32:811-819. [PMID: 36050252 DOI: 10.1016/j.nmd.2022.08.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Revised: 08/10/2022] [Accepted: 08/16/2022] [Indexed: 12/01/2022]
Abstract
The non-dystrophic myotonias are inherited skeletal muscle disorders characterized by skeletal muscle stiffness after voluntary contraction, without muscle atrophy. Based on their clinical features, non-dystrophic myotonias are classified into myotonia congenita, paramyotonia congenita, and sodium channel myotonia. Using whole-exome next-generation sequencing, we identified a L703P mutation (c.2108T>C, p.L703P) in SCN4A in a Chinese family diagnosed with non-dystrophic myotonias. The clinical findings of patients in this family included muscle stiffness and hypertrophy. The biophysical properties of wildtype and mutant channels were investigated using whole-cell patch clamp. L703P causes both gain-of-function and loss-of-function changes in Nav1.4 properties, including decreased current density, impaired recovery, enhanced activation and slow inactivation. Our study demonstrates that L703P is a pathogenic variant for myotonia, and provides additional electrophysiological information for understanding the pathogenic mechanism of SCN4A-associated channelopathies.
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Affiliation(s)
- Qing Ke
- Department of Neurology, the First Affiliated Hospital, Zhejiang University School of Medicine. #79 Qingchun Road, Hangzhou, Zhejiang 310003, P.R. China.
| | - Youcheng Zhao
- Department of Anesthesiology, Zhejiang Provincial People's Hospital, P.R. China
| | - Yuezhou Li
- The Children's hospital, Zhejiang university school of medicine, P.R. China
| | - Jia Ye
- The Children's hospital, Zhejiang university school of medicine, P.R. China
| | - Siyang Tang
- The Children's hospital, Zhejiang university school of medicine, P.R. China
| | - Fangping He
- Department of Neurology, the First Affiliated Hospital, Zhejiang University School of Medicine. #79 Qingchun Road, Hangzhou, Zhejiang 310003, P.R. China
| | - Fang Ji
- Department of Neurology, the First Affiliated Hospital, Zhejiang University School of Medicine. #79 Qingchun Road, Hangzhou, Zhejiang 310003, P.R. China
| | - Xuejiao Dai
- Department of Neurology, the First Affiliated Hospital, Zhejiang University School of Medicine. #79 Qingchun Road, Hangzhou, Zhejiang 310003, P.R. China
| | - Jie Ni
- Department of Neurology, the First Affiliated Hospital, Zhejiang University School of Medicine. #79 Qingchun Road, Hangzhou, Zhejiang 310003, P.R. China
| | - Yi Li
- Department of Neurology, the First Affiliated Hospital, Zhejiang University School of Medicine. #79 Qingchun Road, Hangzhou, Zhejiang 310003, P.R. China
| | - Robert C Griggs
- Department of Neurology, University of Rochester School of Medicine and Dentistry, Rochester, New York, USA.
| | - Xiaoyang Cheng
- Department of Neurology, Yale University School of Medicine, New Haven, Connecticut 06510, US; Center for Neuroscience & Regeneration Research, Yale University, New Haven, Connecticut 06510, US; Center for Rehabilitation Research, VA Connecticut Healthcare System, West Haven, Connecticut 06516, US.
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Functional Voltage-Gated Sodium Channels Are Present in the Human B Cell Membrane. Cells 2022; 11:cells11071225. [PMID: 35406789 PMCID: PMC8998058 DOI: 10.3390/cells11071225] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Revised: 03/31/2022] [Accepted: 04/03/2022] [Indexed: 02/04/2023] Open
Abstract
B cells express various ion channels, but the presence of voltage-gated sodium (NaV) channels has not been confirmed in the plasma membrane yet. In this study, we have identified several NaV channels, which are expressed in the human B cell membrane, by electrophysiological and molecular biology methods. The sensitivity of the detected sodium current to tetrodotoxin was between the values published for TTX-sensitive and TTX-insensitive channels, which suggests the co-existence of multiple NaV1 subtypes in the B cell membrane. This was confirmed by RT-qPCR results, which showed high expression of TTX-sensitive channels along with the lower expression of TTX-insensitive NaV1 channels. The biophysical characteristics of the currents also supported the expression of multiple NaV channels. In addition, we investigated the potential functional role of NaV channels by membrane potential measurements. Removal of Na+ from the extracellular solution caused a reversible hyperpolarization, supporting the role of NaV channels in shaping and maintaining the resting membrane potential. As this study was mainly limited to electrophysiological properties, we cannot exclude the possible non-canonical functions of these channels. This work concludes that the presence of voltage-gated sodium channels in the plasma membrane of human B cells should be recognized and accounted for in the future.
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MacKenzie TMG, Abderemane-Ali F, Garrison CE, Minor DL, Bois JD. Differential effects of modified batrachotoxins on voltage-gated sodium channel fast and slow inactivation. Cell Chem Biol 2021; 29:615-624.e5. [PMID: 34963066 PMCID: PMC9035044 DOI: 10.1016/j.chembiol.2021.12.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Revised: 09/14/2021] [Accepted: 11/29/2021] [Indexed: 11/19/2022]
Abstract
Voltage-gated sodium channels (NaVs) are targets for a number of acute poisons. Many of these agents act as allosteric modulators of channel activity and serve as powerful chemical tools for understanding channel function. Herein, we detail studies with batrachotoxin (BTX), a potent steroidal amine, and three ester derivatives prepared through de novo synthesis against recombinant NaV subtypes (rNaV1.4 and hNaV1.5). Two of these compounds, BTX-B and BTX-cHx, are functionally equivalent to BTX, hyperpolarizing channel activation and blocking both fast and slow inactivation. BTX-yne-a C20-n-heptynoate ester-is a conspicuous outlier, eliminating fast but not slow inactivation. This property differentiates BTX-yne among other NaV modulators as a unique reagent that separates inactivation processes. These findings are supported by functional studies with bacterial NaVs (BacNaVs) that lack a fast inactivation gate. The availability of BTX-yne should advance future efforts aimed at understanding NaV gating mechanisms and designing allosteric regulators of NaV activity.
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Affiliation(s)
- Tim M G MacKenzie
- Department of Chemistry, Stanford University, 337 Campus Drive, Stanford, CA 94305, USA
| | - Fayal Abderemane-Ali
- Cardiovascular Research Institute, University of California, San Francisco, Box 3122, 555 Mission Bay Boulevard South, Rm. 452Z, San Francisco, CA 94158-9001, USA
| | - Catherine E Garrison
- Department of Chemistry, Stanford University, 337 Campus Drive, Stanford, CA 94305, USA
| | - Daniel L Minor
- Cardiovascular Research Institute, University of California, San Francisco, Box 3122, 555 Mission Bay Boulevard South, Rm. 452Z, San Francisco, CA 94158-9001, USA; Departments of Biochemistry and Biophysics, and Cellular and Molecular Pharmacology, University of California, San Francisco, CA 94158-9001, USA; California Institute for Quantitative Biomedical Research, University of California, San Francisco, CA 94158-9001, USA; Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, CA 94158-9001, USA; Molecular Biophysics and Integrated Bio-imaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
| | - J Du Bois
- Department of Chemistry, Stanford University, 337 Campus Drive, Stanford, CA 94305, USA.
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Santillo S. Changes in Biophysical Properties of Undifferentiated SH-SY5Y Cells During Long-term Cultures. Neuroscience 2021; 482:143-158. [PMID: 34826533 DOI: 10.1016/j.neuroscience.2021.10.033] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 10/14/2021] [Accepted: 10/18/2021] [Indexed: 11/25/2022]
Abstract
The electrophysiological properties of undifferentiated SH-SY5Y cells were examined during cultures prolonged even to 20 days by measuring the passive and active membrane properties at 5 days interval, as well as the spontaneous spiking activity. The results showed that culturing this cell for long time affected not only membrane shape but also their electrophysiological properties. In particular, these cells considerably varied their sodium and potassium voltage-dependent currents, various channels kinetic features and their excitable properties. These modifications would synergically contribute to the bioelectrical conversion of these cells and could be part of a more complex machinery with which the tumoral cell would regulate its survival advantage and resilience. Understanding these processes could add a new clue to the exploitation of this preclinical human neuronal model.
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Affiliation(s)
- Silvia Santillo
- Istituto di Scienze Applicate e Sistemi Intelligenti del CNR (ISASI-CNR), Naples, Italy.
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8
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Tan X, Hu S, Xie Z, Mei H, Liu Y, Yin L, Shi P, Chen Q, Sang D. Identification of a SCN4A mutation in a large Chinese family with atypical normokalemic periodic paralysis using whole-exome sequencing. J Int Med Res 2020; 48:300060520953643. [PMID: 32962503 PMCID: PMC7517994 DOI: 10.1177/0300060520953643] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
OBJECTIVES Normokalemic periodic paralysis (NormoKPP) of skeletal muscle is an autosomal dominant disorder caused by mutations in the gene encoding voltage-gated sodium channel protein type 4 subunit alpha (SCN4A), which leads to ion channel dysfunction. Little is known about the relationship between genotype and the clinical symptoms of NormoKPP. The present study aimed to evaluate the genetic variation in a large Chinese family with NormoKPP. The patients in this pedigree did not respond to saline treatment, but calcium gluconate treatment was effective. METHODS We performed a series of clinical examinations and genetic analyses, using whole-exome and Sanger sequencing, to examine the mutation status of SCN4A in a Chinese family segregating for NormoKPP. RESULTS Whole-exome sequencing revealed a c.2111C>T substitution in SCN4A in most of the affected family members. This mutation results in the amino acid substitution p.T704M. CONCLUSIONS These results support a causative role of this mutation in SCN4A in NormoKPP, and provide information about the relationship between genotype and atypical clinical symptoms.
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Affiliation(s)
- XinYu Tan
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - SongNian Hu
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Zongyu Xie
- Department of Image Center, the First Affiliated Hospital of Bengbu Medical College, Bengbu, China
| | - Hailiang Mei
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Yang Liu
- Department of Neurology, the First Affiliated Hospital of Bengbu Medical College, Bengbu, China
| | - Liang Yin
- Department of Neurology, the First Affiliated Hospital of Bengbu Medical College, Bengbu, China
| | - Peng Shi
- Department of Neurology, the First Affiliated Hospital of Bengbu Medical College, Bengbu, China
| | - Qiming Chen
- Department of Neurology, the First Affiliated Hospital of Bengbu Medical College, Bengbu, China
| | - Daoqian Sang
- Department of Neurology, the First Affiliated Hospital of Bengbu Medical College, Bengbu, China
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Encinas AC, Watkins JC, Longoria IA, Johnson JP, Hammer MF. Variable patterns of mutation density among NaV1.1, NaV1.2 and NaV1.6 point to channel-specific functional differences associated with childhood epilepsy. PLoS One 2020; 15:e0238121. [PMID: 32845893 PMCID: PMC7449494 DOI: 10.1371/journal.pone.0238121] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Accepted: 08/10/2020] [Indexed: 11/28/2022] Open
Abstract
Variants implicated in childhood epilepsy have been identified in all four voltage-gated sodium channels that initiate action potentials in the central nervous system. Previous research has focused on the functional effects of particular variants within the most studied of these channels (NaV1.1, NaV1.2 and NaV1.6); however, there have been few comparative studies across channels to infer the impact of mutations in patients with epilepsy. Here we compare patterns of variation in patient and public databases to test the hypothesis that regions of known functional significance within voltage-gated sodium (NaV) channels have an increased burden of deleterious variants. We assessed mutational burden in different regions of the Nav channels by (1) performing Fisher exact tests on odds ratios to infer excess variants in domains, segments, and loops of each channel in patient databases versus public “control” databases, and (2) comparing the cumulative distribution of variant sites along DNA sequences of each gene in patient and public databases (i.e., independent of protein structure). Patient variant density was concordant among channels in regions known to play a role in channel function, with statistically significant higher patient variant density in S4-S6 and DIII-DIV and an excess of public variants in SI-S3, DI-DII, DII-DIII. On the other hand, channel-specific patterns of patient burden were found in the NaV1.6 inactivation gate and NaV1.1 S5-S6 linkers, while NaV1.2 and NaV1.6 S4-S5 linkers and S5 segments shared patient variant patterns that contrasted with those in NaV1.1. These different patterns may reflect different roles played by the NaV1.6 inactivation gate in action potential propagation, and by NaV1.1 S5-S6 linkers in loss of function and haploinsufficiency. Interestingly, NaV1.2 and NaV1.6 both lack amino acid substitutions over significantly long stretches in both the patient and public databases suggesting that new mutations in these regions may cause embryonic lethality or a non-epileptic disease phenotype.
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Affiliation(s)
- Alejandra C. Encinas
- Graduate Program in Genetics, University of Arizona, Tucson, Arizona, United States of America
| | - Joseph C. Watkins
- Department of Mathematics, University of Arizona, Tucson, Arizona, United States of America
| | - Iris Arenas Longoria
- Department of Mathematics, University of Arizona, Tucson, Arizona, United States of America
| | | | - Michael F. Hammer
- Department of Neurology, University of Arizona, Tucson, Arizona, United States of America
- * E-mail:
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In vivo assessment of interictal sarcolemmal membrane properties in hypokalaemic and hyperkalaemic periodic paralysis. Clin Neurophysiol 2020; 131:816-827. [PMID: 32066100 DOI: 10.1016/j.clinph.2019.12.414] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Revised: 11/26/2019] [Accepted: 12/10/2019] [Indexed: 01/07/2023]
Abstract
OBJECTIVE Hypokalaemic periodic paralysis (HypoPP) is caused by mutations of Cav1.1, and Nav1.4 which result in an aberrant gating pore current. Hyperkalaemic periodic paralysis (HyperPP) is due to a gain-of-function mutation of the main alpha pore of Nav1.4. This study used muscle velocity recovery cycles (MVRCs) to investigate changes in interictal muscle membrane properties in vivo. METHODS MVRCs and responses to trains of stimuli were recorded in tibialis anterior and compared in patients with HyperPP(n = 7), HypoPP (n = 10), and normal controls (n = 26). RESULTS Muscle relative refractory period was increased, and early supernormality reduced in HypoPP, consistent with depolarisation of the interictal resting membrane potential. In HyperPP the mean supernormality and residual supernormality to multiple conditioning stimuli were increased, consistent with increased inward sodium current and delayed repolarisation, predisposing to spontaneous myotonic discharges. CONCLUSIONS The in vivo findings suggest the interictal resting membrane potential is depolarized in HypoPP, and mostly normal in HyperPP. The MVRC findings in HyperPP are consistent with presence of a window current, previously proposed on the basis of in vitro expression studies. Although clinically similar, HyperPP was electrophysiologically distinct from paramyotonia congenita. SIGNIFICANCE MVRCs provide important in vivo data that complements expression studies of ion channel mutations.
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Ghotbeddin Z, Heysieattalab S, Borjkhani M, Mirnajafi-Zadeh J, Semnanian S, Hosseinmardi N, Janahmadi M. Ca 2+ Channels Involvement in Low-Frequency Stimulation-Mediated Suppression of Intrinsic Excitability of Hippocampal CA1 Pyramidal Cells in a Rat Amygdala Kindling Model. Neuroscience 2019; 406:234-248. [PMID: 30885638 DOI: 10.1016/j.neuroscience.2019.03.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2018] [Revised: 03/04/2019] [Accepted: 03/05/2019] [Indexed: 12/26/2022]
Abstract
Low-frequency stimulation has demonstrated promising seizure suppression in animal models of epilepsy, while the mechanism of the effect is still debated. Changes in intrinsic properties have been recognized as a prominent pathophysiologically relevant feature of numerous neurological disorders including epilepsy. Here, it was evaluated whether LFS can preserve the intrinsic neuronal electrophysiological properties in a rat model of epilepsy, focusing on the possible involvement of voltage-gated Ca2+ channels. The amygdala kindling model was induced by 3 s monophasic square wave pulses (50 Hz, 1 ms duration, 12times/day at 5 min intervals). Both LFS alone and kindled plus LFS (KLFS) groups received four packages of LFS (each consisting of 200 monophasic square pulses, 0.1 ms pulse duration at 1 Hz with the after discharge threshold intensity), which in KLFS rats was applied immediately after kindling induction. Whole-cell patch-clamp recordings were made in the presence of fast synaptic blockers 24 h after the last kindling stimulations or following kindling stimulations plus LFS application. In the KLFS group, both the rebound excitation and kindling-induced intrinsic hyperexcitability were decreased, associated with a regular intrinsic firing as indicated by a lower coefficient of variation. The amplitude of afterdepolarization (ADP) and its area under the curve were both decreased in the KLFS group compared to the kindled group. LFS prevented the increasing effect of kindling on Ca2+ currents in the KLFS group. Findings provided evidence for a novel form of epileptiform activity suppression by LFS in the presence of synaptic blockade possibly by decreasing Ca2+ currents.
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Affiliation(s)
- Zohreh Ghotbeddin
- Department of Physiology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran; Department of Physiology, Faculty of Veterinary Medicine, Shahid Chamran University of Ahvaz, Ahvaz, Iran; Stem Cell and Transgenic Technology Research Center, Shahid Chamran University of Ahvaz, Ahvaz, Iran
| | | | - Mehdi Borjkhani
- Department of Electrical Engineering, Urmia University of Technology, Urmia, Iran
| | - Javad Mirnajafi-Zadeh
- Department of Physiology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
| | - Saeed Semnanian
- Department of Physiology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
| | - Narges Hosseinmardi
- Neuroscience Research Center and Department of Physiology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Mahyar Janahmadi
- Neuroscience Research Center and Department of Physiology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
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12
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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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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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Yin L, Rasch MJ, He Q, Wu S, Dou F, Shu Y. Selective Modulation of Axonal Sodium Channel Subtypes by 5-HT1A Receptor in Cortical Pyramidal Neuron. Cereb Cortex 2018; 27:509-521. [PMID: 26494800 DOI: 10.1093/cercor/bhv245] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Serotonergic innervation of the prefrontal cortex (PFC) modulates neuronal activity and PFC functions. However, the cellular mechanism for serotonergic modulation of neuronal excitability remains unclear. We performed patch-clamp recording at the axon of layer-5 pyramidal neurons in rodent PFC slices. We found surprisingly that the activation of 5-HT1A receptors selectively inhibits Na+ currents obtained at the axon initial segment (AIS) but not those at the axon trunk. In addition, Na+ channel subtype NaV1.2 but not NaV1.6 at the AIS is selectively modulated by 5-HT1A receptors. Further experiments revealed that the inhibitory effect is attributable to a depolarizing shift of the activation curve and a facilitation of slow inactivation of AIS Na+ currents. Consistently, dual somatic and axonal recording and simulation results demonstrate that the activation of 5-HT1A receptors could decrease the success rate of action potential (AP) backpropagation toward the somatodendritic compartments, enhancing the segregation of axonal and dendritic activities. Together, our results reveal a selective modulation of NaV1.2 distributed at the proximal AIS region and AP backpropagation by 5-HT1A receptors, suggesting a potential mechanism for serotonergic regulation of functional polarization in the dendro-axonal axis, synaptic plasticity and PFC functions.
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Affiliation(s)
- Luping Yin
- Institute of Neuroscience and State Key Laboratory of Neuroscience, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 200031, China
| | - Malte J Rasch
- State Key Laboratory of Cognitive Neuroscience and Learning and IDG/McGovern Institute for Brain Research, School of Brain and Cognitive Sciences, the Collaborative Innovation Center for Brain Science
| | - Quansheng He
- State Key Laboratory of Cognitive Neuroscience and Learning and IDG/McGovern Institute for Brain Research, School of Brain and Cognitive Sciences, the Collaborative Innovation Center for Brain Science
| | - Si Wu
- State Key Laboratory of Cognitive Neuroscience and Learning and IDG/McGovern Institute for Brain Research, School of Brain and Cognitive Sciences, the Collaborative Innovation Center for Brain Science
| | - Fei Dou
- College of Life Sciences, Beijing Normal University, Beijing 100875, China
| | - Yousheng Shu
- State Key Laboratory of Cognitive Neuroscience and Learning and IDG/McGovern Institute for Brain Research, School of Brain and Cognitive Sciences, the Collaborative Innovation Center for Brain Science
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15
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Meshik X, Choi M, Baker A, Malchow RP, Covnot L, Doan S, Mukherjee S, Farid S, Dutta M, Stroscio MA. Modulation of voltage-gated conductances of retinal horizontal cells by UV-excited TiO2 nanoparticles. NANOMEDICINE-NANOTECHNOLOGY BIOLOGY AND MEDICINE 2017; 13:1031-1040. [DOI: 10.1016/j.nano.2016.11.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Revised: 10/19/2016] [Accepted: 11/17/2016] [Indexed: 12/25/2022]
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16
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Yamane M, Yamashita N, Hida T, Kamiya Y, Nakamura F, Kolattukudy P, Goshima Y. A functional coupling between CRMP1 and Na v1.7 for retrograde propagation of Semaphorin3A signaling. J Cell Sci 2017; 130:1393-1403. [PMID: 28254884 DOI: 10.1242/jcs.199737] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Accepted: 02/22/2017] [Indexed: 12/19/2022] Open
Abstract
Semaphorin3A (Sema3A) is a secreted type of axon guidance molecule that regulates axon wiring through complexes of neuropilin-1 (NRP1) with PlexinA protein receptors. Sema3A regulates the dendritic branching through tetrodotoxin (TTX)-sensitive retrograde axonal transport of PlexA proteins and tropomyosin-related kinase A (TrkA) complex. We here demonstrate that Nav1.7 (encoded by SCN9A), a TTX-sensitive Na+ channel, by coupling with collapsin response mediator protein 1 (CRMP1), mediates the Sema3A-induced retrograde transport. In mouse dorsal root ganglion (DRG) neurons, Sema3A increased co-localization of PlexA4 and TrkA in the growth cones and axons. TTX treatment and RNAi knockdown of Nav1.7 sustained Sema3A-induced colocalized signals of PlexA4 and TrkA in growth cones and suppressed the subsequent localization of PlexA4 and TrkA in distal axons. A similar localization phenotype was observed in crmp1-/- DRG neurons. Sema3A induced colocalization of CRMP1 and Nav1.7 in the growth cones. The half maximal voltage was increased in crmp1-/- neurons when compared to that in wild type. In HEK293 cells, introduction of CRMP1 lowered the threshold of co-expressed exogenous Nav1.7. These results suggest that Nav1.7, by coupling with CRMP1, mediates the axonal retrograde signaling of Sema3A.
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Affiliation(s)
- Masayuki Yamane
- Department of Molecular Pharmacology and Neurobiology, Yokohama City University School of Medicine, Yokohama 236-0004, Japan
| | - Naoya Yamashita
- Department of Molecular Pharmacology and Neurobiology, Yokohama City University School of Medicine, Yokohama 236-0004, Japan .,Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Tomonobu Hida
- Department of Molecular Pharmacology and Neurobiology, Yokohama City University School of Medicine, Yokohama 236-0004, Japan.,RIKEN Brain Science Institute, Saitama 351-0198, Japan
| | - Yoshinori Kamiya
- Department of Anesthesiology, Uonuma Institute of Community Medicine, Niigata University Medical and Dental Hospital, 4132 Urasa, Minami-uonuma, Niigata 949-7302, Japan
| | - Fumio Nakamura
- Department of Molecular Pharmacology and Neurobiology, Yokohama City University School of Medicine, Yokohama 236-0004, Japan
| | - Pappachan Kolattukudy
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL 32816, USA
| | - Yoshio Goshima
- Department of Molecular Pharmacology and Neurobiology, Yokohama City University School of Medicine, Yokohama 236-0004, Japan
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17
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Fan C, Mao N, Lehmann-Horn F, Bürmann J, Jurkat-Rott K. Effects of S906T polymorphism on the severity of a novel borderline mutation I692M in Na v 1.4 cause periodic paralysis. Clin Genet 2016; 91:859-867. [PMID: 27714768 DOI: 10.1111/cge.12880] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Revised: 09/29/2016] [Accepted: 09/30/2016] [Indexed: 11/29/2022]
Abstract
Hyperkalemic periodic paralysis (HyperPP) is a dominantly inherited muscle disease caused by mutations in SCN4A gene encoding skeletal muscle voltage gated Nav 1.4 channels. We identified a novel Nav 1.4 mutation I692M in 14 families out of the 104 genetically identified HyperPP families in the Neuromuscular Centre Ulm and is therefore as frequent as I693T (13 families out of 14 HyperPP families) in Germany. Surprisingly, in 13 families, a known polymorphism S906T was also present. It was on the affected allele in at least 10 families compatible with a possible founder effect in central Europe. All affected members suffered from episodic weakness; myotonia was also common. Compared with I692M patients, I692M-S906T patients had longer weakness episodes, more affected muscles, CK elevation and presence of permanent weakness. Electrophysiological investigation showed that both mutants had incomplete slow inactivation and a hyperpolarizing shift of activation which contribute to membrane depolarization and weakness. Additionally, I692M-S906T significantly enhanced close-state fast inactivation compared with I692M alone, suggesting a higher proportion of inactivated I692M-S906T channels upon membrane depolarization which may facilitate the initiation of weakness episodes and therefore clinical manifestation. Our results suggest that polymorphism S906T has effects on the clinical phenotypic and electrophysiological severity of a novel borderline Nav 1.4 mutation I692M, making the borderline mutation fully penetrant.
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Affiliation(s)
- C Fan
- Division of Neurophysiology, Ulm University, Ulm, Germany
| | - N Mao
- Division of Neurophysiology, Ulm University, Ulm, Germany.,Human Oncology & Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - F Lehmann-Horn
- Division of Neurophysiology, Ulm University, Ulm, Germany
| | - J Bürmann
- Department of Neurology, University Hospital of the Saarland, Homburg, Germany
| | - K Jurkat-Rott
- Dept. of Neurosurgery, Ulm University, Albert-Einstein-Allee 23,89081 Ulm, Germany
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18
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Ghovanloo MR, Aimar K, Ghadiry-Tavi R, Yu A, Ruben PC. Physiology and Pathophysiology of Sodium Channel Inactivation. CURRENT TOPICS IN MEMBRANES 2016; 78:479-509. [PMID: 27586293 DOI: 10.1016/bs.ctm.2016.04.001] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Voltage-gated sodium channels are present in different tissues within the human body, predominantly nerve, muscle, and heart. The sodium channel is composed of four similar domains, each containing six transmembrane segments. Each domain can be functionally organized into a voltage-sensing region and a pore region. The sodium channel may exist in resting, activated, fast inactivated, or slow inactivated states. Upon depolarization, when the channel opens, the fast inactivation gate is in its open state. Within the time frame of milliseconds, this gate closes and blocks the channel pore from conducting any more sodium ions. Repetitive or continuous stimulations of sodium channels result in a rate-dependent decrease of sodium current. This process may continue until the channel fully shuts down. This collapse is known as slow inactivation. This chapter reviews what is known to date regarding, sodium channel inactivation with a focus on various mutations within each NaV subtype and with clinical implications.
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Affiliation(s)
- M-R Ghovanloo
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada
| | - K Aimar
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada
| | - R Ghadiry-Tavi
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada
| | - A Yu
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada
| | - P C Ruben
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada
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19
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SCN5A variant that blocks fibroblast growth factor homologous factor regulation causes human arrhythmia. Proc Natl Acad Sci U S A 2015; 112:12528-33. [PMID: 26392562 DOI: 10.1073/pnas.1516430112] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Nav channels are essential for metazoan membrane depolarization, and Nav channel dysfunction is directly linked with epilepsy, ataxia, pain, arrhythmia, myotonia, and irritable bowel syndrome. Human Nav channelopathies are primarily caused by variants that directly affect Nav channel permeability or gating. However, a new class of human Nav channelopathies has emerged based on channel variants that alter regulation by intracellular signaling or cytoskeletal proteins. Fibroblast growth factor homologous factors (FHFs) are a family of intracellular signaling proteins linked with Nav channel regulation in neurons and myocytes. However, to date, there is surprisingly little evidence linking Nav channel gene variants with FHFs and human disease. Here, we provide, to our knowledge, the first evidence that mutations in SCN5A (encodes primary cardiac Nav channel Nav1.5) that alter FHF binding result in human cardiovascular disease. We describe a five*generation kindred with a history of atrial and ventricular arrhythmias, cardiac arrest, and sudden cardiac death. Affected family members harbor a novel SCN5A variant resulting in p.H1849R. p.H1849R is localized in the central binding core on Nav1.5 for FHFs. Consistent with these data, Nav1.5 p.H1849R affected interaction with FHFs. Further, electrophysiological analysis identified Nav1.5 p.H1849R as a gain-of-function for INa by altering steady-state inactivation and slowing the rate of Nav1.5 inactivation. In line with these data and consistent with human cardiac phenotypes, myocytes expressing Nav1.5 p.H1849R displayed prolonged action potential duration and arrhythmogenic afterdepolarizations. Together, these findings identify a previously unexplored mechanism for human Nav channelopathy based on altered Nav1.5 association with FHF proteins.
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20
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Bugiardini E, Rivolta I, Binda A, Soriano Caminero A, Cirillo F, Cinti A, Giovannoni R, Botta A, Cardani R, Wicklund M, Meola G. SCN4A mutation as modifying factor of Myotonic Dystrophy Type 2 phenotype. Neuromuscul Disord 2015; 25:301-7. [DOI: 10.1016/j.nmd.2015.01.006] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2014] [Revised: 01/09/2015] [Accepted: 01/14/2015] [Indexed: 12/19/2022]
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21
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Tang C, Zhou X, Huang Y, Zhang Y, Hu Z, Wang M, Chen P, Liu Z, Liang S. The tarantula toxin jingzhaotoxin-XI (κ-theraphotoxin-Cj1a) regulates the activation and inactivation of the voltage-gated sodium channel Nav1.5. Toxicon 2014; 92:6-13. [DOI: 10.1016/j.toxicon.2014.09.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2014] [Revised: 09/01/2014] [Accepted: 09/09/2014] [Indexed: 01/28/2023]
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22
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Enhanced slow inactivation of the human skeletal muscle sodium channel causing normokalemic periodic paralysis. Cell Mol Neurobiol 2014; 34:707-14. [PMID: 24682880 DOI: 10.1007/s10571-014-0052-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2014] [Accepted: 03/18/2014] [Indexed: 10/25/2022]
Abstract
Normokalemic periodic paralysis (normoPP) is a type of skeletal muscle function disorder which is characterized by paralysis attack with concomitant normal serum potassium level. We previously reported that R675Q mutation of human skeletal muscle voltage-gated sodium channel α subunit (SCN4A) may be the novel mutation which caused normoPP in Chinese families. However, it is still not clear how this mutation affects the SCN4A channel function. In this study, we used patch-clamp recording to study the function of wild type (WT) and R675Q mutant of SCN4A channels expressed in human embryonic kidney (HEK293) cells. We found that R675Q mutation did not affect the voltage dependence of sodium channel activation. The fast inactivation was also not significantly affected by R675Q mutation. However, R675Q mutation of SCN4A channels exhibited an 11.1 mV hyperpolarized shift in the voltage dependence of slow inactivation and significantly prolonged the recovery from prolonged inactivation state. Our results thus indicate that SCN4A was functionally affected by R675Q mutation, suggesting a possible reason for causing normoPP in Chinese patients.
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23
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Tomašić T, Hartzoulakis B, Zidar N, Chan F, Kirby RW, Madge DJ, Peigneur S, Tytgat J, Kikelj D. Ligand- and Structure-Based Virtual Screening for Clathrodin-Derived Human Voltage-Gated Sodium Channel Modulators. J Chem Inf Model 2013; 53:3223-32. [DOI: 10.1021/ci400505e] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Tihomir Tomašić
- University of Ljubljana, Faculty of Pharmacy, Aškerčeva 7, 1000 Ljubljana, Slovenia
| | - Basil Hartzoulakis
- Xention Limited, Iconix Park, London
Road, Pampisford, Cambridge CB22 3EG, United Kingdom
| | - Nace Zidar
- University of Ljubljana, Faculty of Pharmacy, Aškerčeva 7, 1000 Ljubljana, Slovenia
| | - Fiona Chan
- Xention Limited, Iconix Park, London
Road, Pampisford, Cambridge CB22 3EG, United Kingdom
| | - Robert W. Kirby
- Xention Limited, Iconix Park, London
Road, Pampisford, Cambridge CB22 3EG, United Kingdom
| | - David J. Madge
- Xention Limited, Iconix Park, London
Road, Pampisford, Cambridge CB22 3EG, United Kingdom
| | - Steve Peigneur
- University of Leuven (K. U. Leuven), Toxicology and Pharmacology, Campus Gasthuisberg O&N2, Herestraat 49, P.O. Box 922, 3000 Leuven, Belgium
| | - Jan Tytgat
- University of Leuven (K. U. Leuven), Toxicology and Pharmacology, Campus Gasthuisberg O&N2, Herestraat 49, P.O. Box 922, 3000 Leuven, Belgium
| | - Danijel Kikelj
- University of Ljubljana, Faculty of Pharmacy, Aškerčeva 7, 1000 Ljubljana, Slovenia
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24
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Dejthevaporn C, Papsing C, Phakdeekitcharoen B, Jaovisidha S, Phudhichareonrat S, Witoonpanich R, Pulkes T. Long-term effectiveness of acetazolamide on permanent weakness in hyperkalemic periodic paralysis. Neuromuscul Disord 2013; 23:445-9. [DOI: 10.1016/j.nmd.2013.02.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2012] [Revised: 02/02/2013] [Accepted: 02/07/2013] [Indexed: 11/25/2022]
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25
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Jones DK, Peters CH, Allard CR, Claydon TW, Ruben PC. Proton sensors in the pore domain of the cardiac voltage-gated sodium channel. J Biol Chem 2013; 288:4782-91. [PMID: 23283979 DOI: 10.1074/jbc.m112.434266] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Protons impart isoform-specific modulation of inactivation in neuronal, skeletal muscle, and cardiac voltage-gated sodium (Na(V)) channels. Although the structural basis of proton block in Na(V) channels has been well described, the amino acid residues responsible for the changes in Na(V) kinetics during extracellular acidosis are as yet unknown. We expressed wild-type (WT) and two pore mutant constructs (H880Q and C373F) of the human cardiac Na(V) channel, Na(V)1.5, in Xenopus oocytes. C373F and H880Q both attenuated proton block, abolished proton modulation of use-dependent inactivation, and altered pH modulation of the steady-state and kinetic parameters of slow inactivation. Additionally, C373F significantly reduced the maximum probability of use-dependent inactivation and slow inactivation, relative to WT. H880Q also significantly reduced the maximum probability of slow inactivation and shifted the voltage dependence of activation and fast inactivation to more positive potentials, relative to WT. These data suggest that Cys-373 and His-880 in Na(V)1.5 are proton sensors for use-dependent and slow inactivation and have implications in isoform-specific modulation of Na(V) channels.
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Affiliation(s)
- David K Jones
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
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26
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Martin CA, Siedlecka U, Kemmerich K, Lawrence J, Cartledge J, Guzadhur L, Brice N, Grace AA, Schwiening C, Terracciano CM, Huang CLH. Reduced Na(+) and higher K(+) channel expression and function contribute to right ventricular origin of arrhythmias in Scn5a+/- mice. Open Biol 2012; 2:120072. [PMID: 22773948 PMCID: PMC3390792 DOI: 10.1098/rsob.120072] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2012] [Accepted: 05/11/2012] [Indexed: 12/17/2022] Open
Abstract
Brugada syndrome (BrS) is associated with ventricular tachycardia originating particularly in the right ventricle (RV). We explore electrophysiological features predisposing to such arrhythmic tendency and their possible RV localization in a heterozygotic Scn5a+/- murine model. Na(v)1.5 mRNA and protein expression were lower in Scn5a+/- than wild-type (WT), with a further reduction in the RV compared with the left ventricle (LV). RVs showed higher expression levels of K(v)4.2, K(v)4.3 and KChIP2 in both Scn5a+/- and WT. Action potential upstroke velocity and maximum Na(+) current (I(Na)) density were correspondingly decreased in Scn5a+/-, with a further reduction in the RV. The voltage dependence of inactivation was shifted to more negative values in Scn5a+/-. These findings are predictive of a localized depolarization abnormality leading to slowed conduction. Persistent Na(+) current (I(pNa)) density was decreased in a similar pattern to I(Na). RV transient outward current (I(to)) density was greater than LV in both WT and Scn5a+/-, and had larger time constants of inactivation. These findings were also consistent with the observation that AP durations were smallest in the RV of Scn5a+/-, fulfilling predictions of an increased heterogeneity of repolarization as an additional possible electrophysiological mechanism for arrhythmogenesis in BrS.
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Affiliation(s)
- Claire A Martin
- Physiological Laboratory, University of Cambridge, Downing Site, Cambridge CB2 3EG, UK.
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27
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Channelopathies. Neurogenetics 2012. [DOI: 10.1017/cbo9781139087711.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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28
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Zhao J, Duprè N, Puymirat J, Chahine M. Biophysical characterization of M1476I, a sodium channel founder mutation associated with cold-induced myotonia in French Canadians. J Physiol 2012; 590:2629-44. [PMID: 22250216 DOI: 10.1113/jphysiol.2011.223461] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
M1476I, a French Canadian founder mutation of Na⁺ channel Nav1.4, causes potassium-aggravated myotonia, with cold-induced myotonia as the most distinctive clinical feature. Mexiletine, a class 1B local anaesthetic, relieves the myotonic symptoms of patients carrying the M1476I mutation. We used the patch-clamp method to investigate the functional characteristics of this mutation by heterologous expression in tsA201 cells. The M1476I mutation caused an increased persistent Na⁺ current, a 2- to 3-fold slower fast inactivation, a 6.4 mV depolarizing shift in the midpoint of steady-state inactivation, and an accelerated recovery from fast inactivation compared to the wild-type (WT) channel. Cooling slowed the kinetics of both channel types and increased the amplitude of the persistent current in M1476I channels.Mexiletine suppressed the persistent Na⁺ current generated by the M1476I mutation and blocked both WT and M1476I channels in a use- dependent manner. The inactivation-deficient M1476I channels were less susceptible to mexiletine during repetitive pulses. The decreased use-dependent block of M1476I channels might have resulted from the slower onset of mexiletine block, and/or the faster recovery from mexiletine block, given that the affinity of mexiletine for the inactivated state of the WT and mutant channels was similar. Increased extracellular concentrations of potassium had no effect on either M1476I or WT currents. These results indicated that cooling can augment the disruption of the voltage dependence of fast inactivation by M1476I channels.
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Affiliation(s)
- Juan Zhao
- Le Centre de recherche en neurosciences, Institut universitaire en santé mentale de Québec, 2601 Chemin de Canardière, Quebec, QC, G1J 2G3, Canada
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Fu Y, Struyk A, Markin V, Cannon S. Gating behaviour of sodium currents in adult mouse muscle recorded with an improved two-electrode voltage clamp. J Physiol 2010; 589:525-46. [PMID: 21135045 DOI: 10.1113/jphysiol.2010.199430] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Muscle contraction is triggered by the spread of an action potential along the fibre. The ionic current to generate the action potential is conducted through voltage-activated sodium channels, and mutations of these channels are known to cause several human muscle disorders. Mouse models have been created by introducing point mutations into the sodium channel gene. This achievement has created the need for a high-fidelity technique to record sodium currents from intact mouse muscle fibres. We have optimized a two-electrode voltage clamp, using sharp microelectrodes to preserve the myoplasmic contents. The voltage-dependent behaviour of sodium channel activation, inactivation and slow-inactivation were characterized. The voltage range for these gating behaviours was remarkably hyperpolarized, in comparison to studies in artificial expression systems. These results provide normative data for sodium channels natively expressed in mouse muscle and illustrate the need to modify model simulations of muscle excitability to account for the hyperpolarized shift.
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Affiliation(s)
- Yu Fu
- Program in Neuroscience, UT Southwestern Medical Center, Dallas, TX 75390, USA
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Liao Y, Deprez L, Maljevic S, Pitsch J, Claes L, Hristova D, Jordanova A, Ala-Mello S, Bellan-Koch A, Blazevic D, Schubert S, Thomas EA, Petrou S, Becker AJ, De Jonghe P, Lerche H. Molecular correlates of age-dependent seizures in an inherited neonatal-infantile epilepsy. Brain 2010; 133:1403-14. [DOI: 10.1093/brain/awq057] [Citation(s) in RCA: 137] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Choi JS, Zhang L, Dib-Hajj SD, Han C, Tyrrell L, Lin Z, Wang X, Yang Y, Waxman SG. Mexiletine-responsive erythromelalgia due to a new Nav1.7 mutation showing use-dependent current fall-off. Exp Neurol 2009; 216:383-9. [DOI: 10.1016/j.expneurol.2008.12.012] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2008] [Revised: 12/15/2008] [Accepted: 12/17/2008] [Indexed: 02/01/2023]
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Carboni M, Zhang ZS, Neplioueva V, Starmer CF, Grant AO. Slow sodium channel inactivation and use-dependent block modulated by the same domain IV S6 residue. J Membr Biol 2009; 207:107-17. [PMID: 16477531 DOI: 10.1007/s00232-005-0805-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2004] [Accepted: 10/22/2005] [Indexed: 10/25/2022]
Abstract
Voltage- and/or conformation-dependent association and dissociation of local anesthetic-class drugs from a putative receptor site in domain IV S6 of the sodium channel and slow conformation transitions of the drug-associated channel have been proposed as mechanisms of use- and frequency-dependent reduction in sodium current. To distinguish these possibilities, we have explored the reactivity to covalent modification by thiols and block of the mutations F1760C and F1760A at the putative receptor site of the cardiac sodium channel expressed as stable cell lines in HEK-293 cells. Both mutations decreased steady-state fast inactivation, shifting V1/2h from -86 +/- 1.3 mV (WT) to -72.3 +/- 1.4 mV (F1760C) and -67.7 +/- 1 mV (F1760A). In the absence of drug, the F1760C mutant channel displayed use-dependent current reduction during pulse-train stimulation, and faster onset of slow inactivation. This mutant also retained some sensitivity to lidocaine. In contrast, the F1760A mutant showed no use-dependent current reduction or sensitivity to lidocaine. The covalent-modifying agent MTS-ET enhanced use-dependent current reduction of the F1760C mutant channel only. The use-dependent reduction in current of the covalently modified channel completely recovered with rest. Lidocaine produced no additional block during exposure to MTS-ET-treated cells (MTS-ET 43 +/- 2.7%: MTS-ET lidocaine 47 +/- 4.5%), implying interaction at a common binding site. The data suggest that use-dependent binding at the F1760 site results in enhanced slow inactivation rather than alteration of drug association and dissociation from that site and may be a general mechanism of action of sodium-channel blocking agents.
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Affiliation(s)
- M Carboni
- Department of Pediatrics, Duke University Medical Center, Box 3504, Durham, NC 27710, USA
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Deconstructing voltage sensor function and pharmacology in sodium channels. Nature 2008; 456:202-8. [PMID: 19005548 PMCID: PMC2587061 DOI: 10.1038/nature07473] [Citation(s) in RCA: 227] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2008] [Accepted: 09/30/2008] [Indexed: 12/04/2022]
Abstract
Voltage-activated sodium (Nav) channels are crucial for the generation and propagation of nerve impulses, and as such are amongst the most widely targeted ion channels by toxins and drugs. The four voltage sensors in Nav channels have distinct amino acid sequences, raising fundamental questions about their relative contributions to the function and pharmacology of the channel. Here we use four-fold symmetric voltage-activated potassium (Kv) channels as reporters to examine the contributions of individual Nav channel S3b-S4 paddle motifs to the kinetics of voltage sensor activation and to forming toxin receptors. Our results uncover binding sites for toxins from tarantula and scorpion venom on each of the four paddle motifs in Nav channels and reveal how paddle-specific interactions can be used to reshape Nav channel activity. One paddle motif is unique in that it slows voltage sensor activation and toxins selectively targeting this motif impede Nav channel inactivation. This reporter approach and the principles that emerge will be useful in developing new drugs for treating pain and Nav channelopathies.
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Four-mode gating model of fast inactivation of sodium channel Nav1.2a. Pflugers Arch 2008; 457:103-19. [DOI: 10.1007/s00424-008-0500-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2008] [Revised: 03/18/2008] [Accepted: 03/18/2008] [Indexed: 12/19/2022]
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36
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Xiuhai G, Weiping W, Ke Z, Hongbin W, Yiling S, MaoYanling. Mutations of sodium channel alpha-subunit genes in Chinese patients with normokalemic periodic paralysis. Cell Mol Neurobiol 2007; 28:653-61. [PMID: 18046642 DOI: 10.1007/s10571-007-9231-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2007] [Accepted: 10/23/2007] [Indexed: 11/24/2022]
Abstract
OBJECTIVE In this study, we aim to investigate the clinical features and Mutations of sodium channel alpha-subunit (SCN4A) genes in Chinese patients with normokalemic periodic paralysis (normoKPP). METHODS Six unrelated Chinese families with normoKPP were analyzed in clinical features. Genomic DNA was extracted from peripheral blood leukocytes and amplified with PCR. We screened all 24 exons of SCN4A gene with denaturing high performance liquid chromatography (DHPLC) technology, and then sequence analysis was performed in those who showed heteroduplex as compared with unaffected controls. RESULTS The laboratory tests were within normal ranges. Electromyograms and electrocardiograms were normal. One muscle biopsy was performed with the patient in family 4 after a brief attack of normoKPP. Examination of light microscopy showed no changes, but electronic microscopy showed occasionally degenerating myofibers. The mutations of SCN4A genes were as follows: (1) Met1592Val occurred in family 1. (2) Val-781-Ile occurred with the patient and her father in family 4. (3) Both the patients had a novel mutation g2101a predicting the amino acid exchange Arg675Gln in family 5, which may be a disease-causing mutation. CONCLUSIONS In addition to Val-781-Ile and Met1592Val, the mutation g2101a (Arg675Gln) may be the novel mutation of SCN4A genes in Chinese patients with normoKPP.
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Affiliation(s)
- Guo Xiuhai
- Department of Neurology, Chinese PLA General Hospital, No. 28 Fuxing Road, Beijing, China
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37
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Sheets PL, Jackson JO, Waxman SG, Dib-Hajj SD, Cummins TR. A Nav1.7 channel mutation associated with hereditary erythromelalgia contributes to neuronal hyperexcitability and displays reduced lidocaine sensitivity. J Physiol 2007; 581:1019-31. [PMID: 17430993 PMCID: PMC2170829 DOI: 10.1113/jphysiol.2006.127027] [Citation(s) in RCA: 131] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Mutations in the TTX-sensitive voltage-gated sodium channel subtype Nav1.7 have been implicated in the painful inherited neuropathy, hereditary erythromelalgia. Hereditary erythromelalgia can be difficult to treat and, although sodium channels are targeted by local anaesthetics such as lidocaine (lignocaine), some patients do not respond to treatment with local anaesthetics. This study examined electrophysiological differences in Nav1.7 caused by a hereditary erythromelalgia mutation (N395K) that lies within the local anaesthetic binding site of the channel. The N395K mutation produced a hyperpolarized voltage dependence of activation, slower kinetics of deactivation, and impaired steady-state slow inactivation. Computer simulations indicate that the shift in activation is the major determinant of the hyperexcitability induced by erythromelalgia mutations in sensory neurons, but that changes in slow inactivation can modulate the overall impact on excitability. This study also investigated lidocaine inhibition of the Nav1.7-N395K channel. We show that the N395K mutation attenuates the inhibitory effects of lidocaine on both resting and inactivated Nav1.7. The IC50 for lidocaine was estimated at 500 microM for inactivated wild-type Nav1.7 and 2.8 mM for inactivated Nav1.7-N395K. The N395K mutation also significantly reduced use-dependent inhibition of lidocaine on Nav1.7 current. In contrast, a different hereditary erythromelalgia mutation (F216S), not located in the local anaesthetic binding site, had no effect on lidocaine inhibition of Nav1.7 current. Our observation of reduced lidocaine inhibition on Nav1.7-N395K shows that the residue N395 is critical for lidocaine binding to Nav1.7 and suggests that the response of individuals with hereditary erythromelalgia to lidocaine treatment may be determined, at least in part, by their specific genotype.
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MESH Headings
- Action Potentials/drug effects
- Anesthetics, Local/metabolism
- Anesthetics, Local/pharmacology
- Anesthetics, Local/therapeutic use
- Binding Sites
- Cell Line
- Computer Simulation
- Dose-Response Relationship, Drug
- Erythromelalgia/drug therapy
- Erythromelalgia/genetics
- Erythromelalgia/metabolism
- Ganglia, Spinal/cytology
- Ganglia, Spinal/drug effects
- Ganglia, Spinal/metabolism
- Humans
- Ion Channel Gating/drug effects
- Kinetics
- Lidocaine/metabolism
- Lidocaine/pharmacology
- Lidocaine/therapeutic use
- Models, Neurological
- Mutation
- NAV1.7 Voltage-Gated Sodium Channel
- Nerve Tissue Proteins/genetics
- Nerve Tissue Proteins/metabolism
- Neurons, Afferent/drug effects
- Neurons, Afferent/metabolism
- Sodium Channel Blockers/metabolism
- Sodium Channel Blockers/pharmacology
- Sodium Channel Blockers/therapeutic use
- Sodium Channels/drug effects
- Sodium Channels/genetics
- Sodium Channels/metabolism
- Transfection
- Voltage-Gated Sodium Channel beta-2 Subunit
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Affiliation(s)
- Patrick L Sheets
- Department of Pharmacology and Toxicology, Stark Neurosciences Research Institute, Indiana University School of Medicine, 950 West Walnut St, R2 468, Indianapolis, IN 46202, USA
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Jurkat-Rott K, Lehmann-Horn F. Genotype-phenotype correlation and therapeutic rationale in hyperkalemic periodic paralysis. Neurotherapeutics 2007; 4:216-24. [PMID: 17395131 DOI: 10.1016/j.nurt.2007.02.001] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Familial hyperkalemic periodic paralysis (PP) is a dominantly inherited muscle disease characterized by attacks of flaccid weakness and intermittent myotonia. Some patients experience muscle stiffness that is aggravated by cold and exercise, bordering on the diagnosis of paramyotonia congenita. Hyperkalemic PP and paramyotonia congenita are allelic diseases caused by gain-of-function mutations of the skeletal muscle sodium channel, Nav1.4, which is essential for the generation of skeletal muscle action potentials. In this review, the functional and clinical consequences of the mutations and therapeutic strategies are reported and the differential diagnoses discussed. Also, the question is addressed of whether hyperkalemic PP is truly a different entity than normokalemic PP. Additionally, the differential diagnosis of Andersen-Tawil syndrome in which hyperkalemic PP attacks may occur will be briefly introduced. Last, because hyperkalemic PP has been described to be associated with an R83H mutation of a MiRP2 potassium channel subunit, evidence refuting disease-causality in this case will be discussed.
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39
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Bendahhou S, O'Reilly AO, Duclohier H. Role of hydrophobic residues in the voltage sensors of the voltage-gated sodium channel. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2007; 1768:1440-7. [PMID: 17442264 DOI: 10.1016/j.bbamem.2007.03.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2006] [Revised: 02/07/2007] [Accepted: 03/01/2007] [Indexed: 01/17/2023]
Abstract
The role of hydrophobic residues in voltage sensors S4 of voltage-sensitive ion channels is less documented than that of charged residues. We performed alanine-substitution of branched-sidechain residues contiguous to the third, fourth and fifth positively charged residues in S4s of the first three domains of the sodium channel expressed in HEK cells. These locations were selected because they are close to the arginines and lysines important in gating. Mutations in the first two domains (DIS4 and DIIS4) altered steady-state activation curves. In DIIIS4, the mutation L1131A next to the third arginine greatly slowed inactivation in a manner similar to that for substitutions of charged residues in DIVS4, whereas the mutation L1137A next to the fifth arginine preserved wild-type behaviour. Homology models of domain III, based on the structure of a crystallized mammalian potassium channel, shows that L1131 is located at the interface between S3 and S4 helices, whereas L1137, on the opposite side of S4, does not interact with the voltage sensor. The two mutated residues are closer to each other in domains I and II than in domain III, as may be corroborated by their different electrophysiological effects.
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Affiliation(s)
- Saïd Bendahhou
- Institut de Pharmacologie Moléculaire et Cellulaire, UMR 6097 CNRS, Université de Nice, Sophia Antipolis 660 Route des Lucioles, Sophia-Antipolis, Valbonne, France
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40
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Hanna MG. Genetic neurological channelopathies. ACTA ACUST UNITED AC 2006; 2:252-63. [PMID: 16932562 DOI: 10.1038/ncpneuro0178] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2006] [Accepted: 03/09/2006] [Indexed: 12/14/2022]
Abstract
Ion channels are crucial for the normal function of excitable tissues such as neurons and skeletal muscle. Since the discovery that the paroxysmal muscle disorder periodic paralysis is caused by mutations in genes that encode voltage-gated ion channels, many genetic neurological channelopathies have been defined. These channelopathies include epilepsy syndromes that show a mendelian pattern of inheritance, certain forms of migraine and disorders of cerebellar function, as well as periodic paralysis. The clinical diversity of these disorders relates in part to the tissue-specific expression of the dysfunctional channel, but is probably influenced by other, as yet unidentified, genetic and non-genetic factors. The complementary disciplines of molecular genetics and cellular and in vitro electrophysiology have resulted in significant advances in understanding of the basic molecular pathophysiology of some of these disorders. The single-gene neurological channelopathies are generally regarded as a paradigm for understanding common human paroxysmal disorders, such as epilepsy and migraine. This article reviews the clinical and molecular features of some of the single-gene channelopathies that affect muscle and brain. The possible role of ion-channel functional and genetic variation in predisposing individuals to common forms of human epilepsy and migraine are also considered. The implications for accurate genetic diagnosis and therapeutic intervention are highlighted.
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Affiliation(s)
- Michael G Hanna
- National Hospital for Neurology and Neurosurgery, Queen Square, London, UK.
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41
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Xiong W, Farukhi YZ, Tian Y, Disilvestre D, Li RA, Tomaselli GF. A conserved ring of charge in mammalian Na+ channels: a molecular regulator of the outer pore conformation during slow inactivation. J Physiol 2006; 576:739-54. [PMID: 16873407 PMCID: PMC1890405 DOI: 10.1113/jphysiol.2006.115105] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The molecular mechanisms underlying slow inactivation in sodium channels are elusive. Our results suggest that EEDD, a highly conserved ring of charge in the external vestibule of mammalian voltage-gated sodium channels, undermines slow inactivation. By employing site-directed mutagenesis, we found that charge alterations in this asymmetric yet strong local electrostatic field of the EEDD ring significantly altered the kinetics of slow inactivation gating. Using a non-linear Poisson-Boltzmann equation, quantitative computations of the electrostatic field in a sodium channel structural model suggested a significant electrostatic repulsion between residues E403 and E758 at close proximity. Interestingly, when this electrostatic interaction was eliminated by the double mutation E403C + E758C, the kinetics of recovery from slow inactivation of the double-mutant channel was retarded by 2500% compared to control. These data suggest that the EEDD ring, located within the asymmetric electric field, is a molecular motif that critically modulates slow inactivation in sodium channels.
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Affiliation(s)
- Wei Xiong
- Department of Medicine, Johns Hopkins University School of Medicine, 720 Rutland Ave/Ross 844, Baltimore, MD 21205, USA
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42
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Stocker PJ, Bennett ES. Differential sialylation modulates voltage-gated Na+ channel gating throughout the developing myocardium. ACTA ACUST UNITED AC 2006; 127:253-65. [PMID: 16476705 PMCID: PMC2151503 DOI: 10.1085/jgp.200509423] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Voltage-gated sodium channel function from neonatal and adult rat cardiomyocytes was measured and compared. Channels from neonatal ventricles required an ∼10 mV greater depolarization for voltage-dependent gating events than did channels from neonatal atria and adult atria and ventricles. We questioned whether such gating shifts were due to developmental and/or chamber-dependent changes in channel-associated functional sialic acids. Thus, all gating characteristics for channels from neonatal atria and adult atria and ventricles shifted significantly to more depolarized potentials after removal of surface sialic acids. Desialylation of channels from neonatal ventricles did not affect channel gating. After removal of the complete surface N-glycosylation structures, gating of channels from neonatal atria and adult atria and ventricles shifted to depolarized potentials nearly identical to those measured for channels from neonatal ventricles. Gating of channels from neonatal ventricles were unaffected by such deglycosylation. Immunoblot gel shift analyses indicated that voltage-gated sodium channel α subunits from neonatal atria and adult atria and ventricles are more heavily sialylated than α subunits from neonatal ventricles. The data are consistent with approximately 15 more sialic acid residues attached to each α subunit from neonatal atria and adult atria and ventricles. The data indicate that differential sialylation of myocyte voltage-gated sodium channel α subunits is responsible for much of the developmental and chamber-specific remodeling of channel gating observed here. Further, cardiac excitability is likely impacted by these sialic acid–dependent gating effects, such as modulation of the rate of recovery from inactivation. A novel mechanism is described by which cardiac voltage-gated sodium channel gating and subsequently cardiac rhythms are modulated by changes in channel-associated sialic acids.
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Affiliation(s)
- Patrick J Stocker
- Department of Physiology and Biophysics and Program in Neuroscience, University of South Florida College of Medicine, Tampa, 33612, USA
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43
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Abstract
Voltage-gated sodium channels open (activate) when the membrane is depolarized and close on repolarization (deactivate) but also on continuing depolarization by a process termed inactivation, which leaves the channel refractory, i.e., unable to open again for a period of time. In the “classical” fast inactivation, this time is of the millisecond range, but it can last much longer (up to seconds) in a different slow type of inactivation. These two types of inactivation have different mechanisms located in different parts of the channel molecule: the fast inactivation at the cytoplasmic pore opening which can be closed by a hinged lid, the slow inactivation in other parts involving conformational changes of the pore. Fast inactivation is highly vulnerable and affected by many chemical agents, toxins, and proteolytic enzymes but also by the presence of β-subunits of the channel molecule. Systematic studies of these modulating factors and of the effects of point mutations (experimental and in hereditary diseases) in the channel molecule have yielded a fairly consistent picture of the molecular background of fast inactivation, which for the slow inactivation is still lacking.
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Affiliation(s)
- Werner Ulbricht
- Psychologisches Institut, University of Kiel, Hermann-Rodewald-Strasse 5, D-24118 Kiel, Germany.
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Venance SL, Cannon SC, Fialho D, Fontaine B, Hanna MG, Ptacek LJ, Tristani-Firouzi M, Tawil R, Griggs RC. The primary periodic paralyses: diagnosis, pathogenesis and treatment. ACTA ACUST UNITED AC 2005; 129:8-17. [PMID: 16195244 DOI: 10.1093/brain/awh639] [Citation(s) in RCA: 195] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Periodic paralyses (PPs) are rare inherited channelopathies that manifest as abnormal, often potassium (K)-sensitive, muscle membrane excitability leading to episodic flaccid paralysis. Hypokalaemic (HypoPP) and hyperkalaemic PP and Andersen-Tawil syndrome are genetically heterogeneous. Over the past decade mutations in genes encoding three ion channels, CACN1AS, SCN4A and KCNJ2, have been identified and account for at least 70% of the identified cases of PP and several allelic disorders. No prospective clinical studies have followed sufficiently large cohorts with characterized molecular lesions to draw precise conclusions. We summarize current knowledge of the clinical diagnosis, molecular genetics, genotype-phenotype correlations, pathophysiology and treatment in the PPs. We focus on unresolved issues including (i) Are there additional ion channel defects in cases without defined mutations? (ii) What is the mechanism for depolarization-induced weakness in Hypo PP? and finally (iii) Will detailed electrophysiological studies be able to correctly identify specific channel mutations? Understanding the pathophysiology of the potassium-sensitive PPs ought to reduce genetic complexity, allow subjects to be stratified during future clinical trials and increase the likelihood of observing true clinical effects. Ideally, therapy for the PPs will prevent attacks, avoid permanent weakness and improve quality of life. Moreover, understanding the skeletal muscle channelopathies will hopefully lead to insights into the more common central nervous system channel diseases such as migraine and epilepsy.
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Affiliation(s)
- S L Venance
- Department of Clinical Neurological Sciences, London Health Sciences Centre, London, ON, Canada.
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45
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Bendahhou S, Donaldson MR, Plaster NM, Tristani-Firouzi M, Fu YH, Ptácek LJ. Defective potassium channel Kir2.1 trafficking underlies Andersen-Tawil syndrome. J Biol Chem 2003; 278:51779-85. [PMID: 14522976 DOI: 10.1074/jbc.m310278200] [Citation(s) in RCA: 113] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Andersen-Tawil syndrome is a skeletal and cardiac muscle disease with developmental features caused by mutations in the inward rectifier K+ channel gene KCNJ2. Patients harboring these mutations exhibit extremely variable expressivities. To explore whether these mutations can be correlated with a specific patient phenotype, we expressed both wild-type (WT) and mutant genes cloned into a bi-cistronic vector. Functional expression in human embryonic kidney 293 cells showed that none of the mutant channels express current when present alone. When co-expressed with WT channels, only construct V302M-WT yields inward current. Confocal microscopy fluorescence revealed three patterns of channel expression in the cell: 1) mutations D71V, N216H, R218Q, and pore mutations co-assemble and co-localize to the membrane with the WT and exert a dominant-negative effect on the WT channels; 2) mutation V302M leads to channels that lose their ability to co-assemble with WT and traffic to the cell surface; 3) deletions Delta 95-98 and Delta 314-315 lead to channels that do not traffic to the membrane but retain their ability to co-assemble with WT channels. These data show that the Andersen-Tawil syndrome phenotype may occur through a dominant-negative effect as well as through haplo-insufficiency and reveal amino acids critical in trafficking and conductance of the inward rectifier K+ channels.
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Affiliation(s)
- Saïd Bendahhou
- Department of Human Molecular Biology and Genetics, University of Utah, Salt Lake City, Utah 84112, USA.
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46
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Xiong W, Li RA, Tian Y, Tomaselli GF. Molecular motions of the outer ring of charge of the sodium channel: do they couple to slow inactivation? J Gen Physiol 2003; 122:323-32. [PMID: 12913092 PMCID: PMC2234489 DOI: 10.1085/jgp.200308881] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In contrast to fast inactivation, the molecular basis of sodium (Na) channel slow inactivation is poorly understood. It has been suggested that structural rearrangements in the outer pore mediate slow inactivation of Na channels similar to C-type inactivation in potassium (K) channels. We probed the role of the outer ring of charge in inactivation gating by paired cysteine mutagenesis in the rat skeletal muscle Na channel (rNav1.4). The outer charged ring residues were substituted with cysteine, paired with cysteine mutants at other positions in the external pore, and coexpressed with rat brain beta1 in Xenopus oocytes. Dithiolthreitol (DTT) markedly increased the current in E403C+E758C double mutant, indicating the spontaneous formation of a disulfide bond and proximity of the alpha carbons of these residues of no more than 7 A. The redox catalyst Cu(II) (1,10-phenanthroline)3 (Cu(phe)3) reduced the peak current of double mutants (E403C+E758C, E403C+D1241C, E403C+D1532C, and D1241C+D1532C) at a rate proportional to the stimulation frequency. Voltage protocols that favored occupancy of slow inactivation states completely prevented Cu(phe)3 modification of outer charged ring paired mutants E403C+E758C, E403C+D1241C, and E403C+D1532C. In contrast, voltage protocols that favored slow inactivation did not prevent Cu(phe)3 modification of other double mutants such as E403C+W756C, E403C+W1239C, and E403C+W1531C. Our data suggest that slow inactivation of the Na channel is associated with a structural rearrangement of the outer ring of charge.
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Affiliation(s)
- Wei Xiong
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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Lucet V, Lupoglazoff JM, Fontaine B. [Andersen syndrome, ventricular arrhythmias and channelopathy (a case report)]. Arch Pediatr 2002; 9:1256-9. [PMID: 12536108 DOI: 10.1016/s0929-693x(02)00124-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
INTRODUCTION Recent advances in molecular genetic research have provided new insights into severe ventricular arrhythmias related to channelopathies. CASE REPORT A case of Andersen's syndrome followed during fourteen years is reported. This rare familial periodic paralysis is characterized by its association with dysmorphic features (micrognatia) and ventricular arrhythmias. COMMENTS Andersen's syndrome has been attributed to a mutation in the KCNJ2 gene which is involved not only in stabilizing cardiac rhythm, but also in modulating the excitability of skeletal muscle and in morphogenesis. This disease must be distinguished from hyperkalemic periodic paralysis due to a mutation in the skeletal muscle sodium channel gene (SCN4A) and from hypokalemic periodic paralysis related to dihydropyridine receptor mutation (CACNL1A3). Furthermore, it may not be confused with others rhythmic channelopathies (long QT syndromes, catecholaminergic polymorphic ventricular tachycardia and Brugada's syndrome).
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MESH Headings
- Adolescent
- Adult
- Child
- Chromosomes, Human, Pair 17/genetics
- Diagnosis, Differential
- Glycogen Storage Disease Type IV/diagnosis
- Glycogen Storage Disease Type IV/drug therapy
- Glycogen Storage Disease Type IV/genetics
- Humans
- Male
- Micrognathism/genetics
- Mutation
- Paralyses, Familial Periodic/diagnosis
- Paralyses, Familial Periodic/drug therapy
- Paralyses, Familial Periodic/genetics
- Potassium Channels, Inwardly Rectifying/genetics
- Tachycardia, Ventricular/diagnosis
- Tachycardia, Ventricular/drug therapy
- Tachycardia, Ventricular/genetics
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Affiliation(s)
- V Lucet
- Unité de rythmologie pédiatrique, Château des Côtes, 78350 Les Loges-en-Josas, France.
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48
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Abstract
Ion channels are complex proteins that span the lipid bilayer of the cell membrane, where they orchestrate the electrical signals necessary for normal function of the central nervous system, peripheral nerve, and both skeletal and cardiac muscle. The role of ion channel defects in the pathogenesis of numerous disorders, many of them neuromuscular, has become increasingly apparent over the last decade. Progress in molecular biology has allowed cloning and expression of genes that encode channel proteins, while comparable advances in biophysics, including patch-clamp electrophysiology and related techniques, have made the study of expressed proteins at the level of single channel molecules possible. Understanding the molecular basis of ion channel function and dysfunction will facilitate both the accurate classification of these disorders and the rational development of specific therapeutic interventions. This review encompasses clinical, genetic, and pathophysiological aspects of ion channels disorders, focusing mainly on those with neuromuscular manifestations.
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Affiliation(s)
- Kleopas A Kleopa
- Department of Neurology, University of Pennsylvania School of Medicine, 122 College Hall, Philadelphia, PA 19104, USA
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49
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Bendahhou S, Cummins TR, Kula RW, Fu YH, Ptácek LJ. Impairment of slow inactivation as a common mechanism for periodic paralysis in DIIS4-S5. Neurology 2002; 58:1266-72. [PMID: 11971097 DOI: 10.1212/wnl.58.8.1266] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
BACKGROUND Mutations in the human skeletal muscle sodium channels are associated with hyperKPP, hypoKPP, paramyotonia congenita, and potassium-aggravated myotonia. This article describes the clinical manifestations of a patient with hyperKPP carrying a mutation (L689I) occurring in the linker DIIS4-S5 and its functional expression in a mammalian system. OBJECTIVE To correlate the clinical manifestations of hyperkalemic periodic paralysis (hyperKPP) with the functional expression of a sodium channel mutation. METHODS The mutation was introduced into a mammalian expression vector and expressed in the human embryonic kidney 293 cells. The functional expression of the L689I and that of the wild-type channels was monitored using the whole cell voltage-clamp technique. RESULTS There was no change in the kinetics of fast inactivation, and inactivation curves were indistinguishable from that of wild-type channels. However, the L689I mutation caused a hyperpolarizing shift in the voltage dependence of activation and the mutant channels showed an impaired slow inactivation process. In addition, the mutant channels have a larger persistent current at -40 mV where window current may occur. CONCLUSIONS The L689I mutation has similar effects to the T704M mutation and causes hyperKPP in this family. Because both of these hyperKPP mutations cause episodic muscle weakness, and because patients harboring another mutation (I693T) also can have episodic weakness, it is hypothesized that mutations occurring in this region of the sodium channel may cause episodic weakness through an impaired slow inactivation process coupled with enhanced activation.
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Affiliation(s)
- S Bendahhou
- Howard Hughes Medical Institute, Eccles Institute of Human Genetics, University of Utah, Salt Lake City 84112, USA.
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50
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Lehmann-Horn F, Jurkat-Rott K, Rüdel R. Periodic paralysis: understanding channelopathies. Curr Neurol Neurosci Rep 2002; 2:61-9. [PMID: 11898585 DOI: 10.1007/s11910-002-0055-9] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Familial periodic paralyses are typical channelopathies (i.e., caused by functional disturbances of ion channel proteins). The episodes of flaccid muscle weakness observed in these disorders are due to underexcitability of sarcolemma leading to a silent electromyogram and the lack of action potentials even upon electrical stimulation. Interictally, ion channel malfunction is well compensated, so that special exogenous or endogenous triggers are required to produce symptoms in the patients. An especially obvious trigger is the level of serum potassium (K+), the ion responsible for resting membrane potential and degree of excitability. The clinical symptoms can be caused by mutations in genes coding for ion channels that mediate different functions for maintaining the resting potential or propagating the action potential, the basis of excitability. The phenotype is determined by the type of functional defect brought about by the mutations, rather than the channel effected, because the contrary phenotypes hyperkalemic periodic paralysis (HyperPP) and hypokalemic periodic paralysis (HypoPP) may be caused by point mutations in the same gene. Still, the common mechanism for inexcitability in all known episodic-weakness phenotypes is a long-lasting depolarization that inactivates sodium ion (Na+) channels, initiating the action potential.
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Affiliation(s)
- Frank Lehmann-Horn
- Department of Physiology, Ulm University, Albert-Einstein-Allee II, Ulm 89069, Germany.
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