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Akbari Ahangar A, Elhanafy E, Blanton H, Li J. Mapping structural distribution and gating-property impacts of disease-associated mutations in voltage-gated sodium channels. iScience 2024; 27:110678. [PMID: 39286500 PMCID: PMC11404175 DOI: 10.1016/j.isci.2024.110678] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2024] [Revised: 06/18/2024] [Accepted: 08/02/2024] [Indexed: 09/19/2024] Open
Abstract
Thousands of voltage-gated sodium (Nav) channel variants contribute to a variety of disorders, including epilepsy, cardiac arrhythmia, and pain disorders. Yet, the effects of more variants remain unclear. The conventional gain-of-function (GoF) or loss-of-function (LoF) classifications are frequently employed to interpret mutations' effects and guide therapy for sodium channelopathies. Our study challenges this binary classification by analyzing 525 mutations associated with 34 diseases across 366 electrophysiology studies, revealing that diseases with similar GoF/LoF effects can stem from unique molecular mechanisms. Utilizing UniProt data, we mapped over 2,400 disease-associated missense mutations across Nav channels. This analysis pinpoints key mutation hotspots and maps patterns of gating-property impacts for the mutations, respectively, located around the selectivity filter, activation gate, fast inactivation region, and voltage-sensing domains. This study shows great potential to enhance prediction accuracy for mutational effects based on the structural context, paving the way for targeted drug design in precision medicine.
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Affiliation(s)
- Amin Akbari Ahangar
- Department of Biomolecular Sciences, School of Pharmacy, University of Mississippi, Oxford, MS 38677, USA
| | - Eslam Elhanafy
- Department of Biomolecular Sciences, School of Pharmacy, University of Mississippi, Oxford, MS 38677, USA
| | - Hayden Blanton
- Department of Biomolecular Sciences, School of Pharmacy, University of Mississippi, Oxford, MS 38677, USA
| | - Jing Li
- Department of Biomolecular Sciences, School of Pharmacy, University of Mississippi, Oxford, MS 38677, USA
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Elhanafy E, Ahangar AA, Roth R, Gamal El-Din TM, Bankston JR, Li J. ELUCIDATING THE DIFFERENTIAL IMPACTS OF EQUIVALENT GATING-CHARGE MUTATIONS IN VOLTAGE-GATED SODIUM CHANNELS. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.09.09.612021. [PMID: 39314455 PMCID: PMC11419121 DOI: 10.1101/2024.09.09.612021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 09/25/2024]
Abstract
Voltage-gated sodium (Nav) channels are pivotal for cellular signaling and mutations in Nav channels can lead to excitability disorders in cardiac, muscular, and neural tissues. A major cluster of pathological mutations localizes in the voltage-sensing domains (VSDs), resulting in either gain-of-function (GoF), loss-of-function (LoF) effects, or both. However, the mechanism behind this functional divergence of mutations at equivalent positions remains elusive. Through hotspot analysis, we identified three gating charges (R1, R2, and R3) as major mutational hotspots in VSDs. The same amino-acid substitutions at equivalent gating-charge positions in VSDI and VSDII of the cardiac sodium channel Nav1.5 show differential gating-property impacts in electrophysiology measurements. We conducted 120 μs molecular dynamics (MD) simulations on wild-type and six mutants to elucidate the structural basis of their differential impacts. Our μs-scale MD simulations with applied external electric fields captured VSD state transitions and revealed the differential structural dynamics between equivalent R-to-Q mutants. Notably, we observed transient leaky conformations in some mutants during structural transitions, offering a detailed structural explanation for gating-pore currents. Our salt-bridge network analysis uncovered VSD-specific and state-dependent interactions among gating charges, countercharges, and lipids. This detailed analysis elucidated how mutations disrupt critical electrostatic interactions, thereby altering VSD permeability and modulating gating properties. By demonstrating the crucial importance of considering the specific structural context of each mutation, our study represents a significant leap forward in understanding structure-function relationships in Nav channels. Our work establishes a robust framework for future investigations into the molecular basis of ion channel-related disorders.
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Affiliation(s)
- Eslam Elhanafy
- Department of Biomolecular Sciences, School of Pharmacy, University of Mississippi, Oxford, MS
| | - Amin Akbari Ahangar
- Department of Biomolecular Sciences, School of Pharmacy, University of Mississippi, Oxford, MS
| | - Rebecca Roth
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus, Aurora, CO
| | | | - John R Bankston
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus, Aurora, CO
| | - Jing Li
- Department of Biomolecular Sciences, School of Pharmacy, University of Mississippi, Oxford, MS
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Glazer AM, Yang T, Li B, Page D, Fouda M, Wada Y, Lancaster MC, O’Neill MJ, Muhammad A, Gao X, Ackerman MJ, Sanatani S, Ruben PC, Roden DM. Multifocal Ectopic Purkinje Premature Contractions due to neutralization of an SCN5A negative charge: structural insights into the gating pore hypothesis. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.13.580021. [PMID: 38405820 PMCID: PMC10888965 DOI: 10.1101/2024.02.13.580021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/27/2024]
Abstract
Background We identified a novel SCN5A variant, E171Q, in a neonate with very frequent ectopy and reduced ejection fraction which normalized after arrhythmia suppression by flecainide. This clinical picture is consistent with multifocal ectopic Purkinje-related premature contractions (MEPPC). Most previous reports of MEPPC have implicated SCN5A variants such as R222Q that neutralize positive charges in the S4 voltage sensor helix of the channel protein NaV1.5 and generate a gating pore current. Methods and Results E171 is a highly conserved negatively-charged residue located in the S2 transmembrane helix of NaV1.5 domain I. E171 is a key component of the Gating Charge Transfer Center, a region thought to be critical for normal movement of the S4 voltage sensor helix. We used heterologous expression, CRISPR-edited induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs), and molecular dynamics simulations to demonstrate that E171Q generates a gating pore current, which was suppressed by a low concentration of flecainide (IC50 = 0.71±0.07 µM). R222Q shifts voltage dependence of activation and inactivation in a negative direction but we observed positive shifts with E171Q. E171Q iPSC-CMs demonstrated abnormal spontaneous activity and prolonged action potentials. Molecular dynamics simulations revealed that both R222Q and E171Q proteins generate a water-filled permeation pathway that underlies generation of the gating pore current. Conclusion Previously identified MEPPC-associated variants that create gating pore currents are located in positively-charged residues in the S4 voltage sensor and generate negative shifts in the voltage dependence of activation and inactivation. We demonstrate that neutralizing a negatively charged S2 helix residue in the Gating Charge Transfer Center generates positive shifts but also create a gating pore pathway. These findings implicate the gating pore pathway as the primary functional and structural determinant of MEPPC and widen the spectrum of variants that are associated with gating pore-related disease in voltage-gated ion channels.
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Affiliation(s)
| | - Tao Yang
- Vanderbilt University Medical Center, Nashville, TN, USA
| | - Bian Li
- Vanderbilt University Medical Center, Nashville, TN, USA
- Current address: Regeneron Pharmaceuticals Inc., Tarrytown NY, USA. Bian Li contributed to this article as an employee of Vanderbilt University Medical Center and the views expressed do not necessarily represent the views of Regeneron Pharmaceuticals Inc
| | - Dana Page
- Simon Fraser University, Burnaby, BC, Canada
| | | | - Yuko Wada
- Vanderbilt University Medical Center, Nashville, TN, USA
| | | | | | | | - Xiaozhi Gao
- Mayo Clinic College of Medicine and Science, Mayo Foundation, Rochester, MN, USA
| | - Michael J. Ackerman
- Mayo Clinic College of Medicine and Science, Mayo Foundation, Rochester, MN, USA
| | | | | | - Dan M. Roden
- Vanderbilt University Medical Center, Nashville, TN, USA
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Li W, Wu CX, Hou JW, Sun J, Wang QS, Zhang PP, Yu Y, Yang M, Chen M, Mo BF, Wang YP, Li YG. Higher Sodium Channel Excitability in Cardiac Purkinje Fibers: Implications for Multifocal Ectopic Purkinje-Related Premature Contractions. JACC Clin Electrophysiol 2023; 9:2477-2490. [PMID: 37831033 DOI: 10.1016/j.jacep.2023.08.029] [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: 02/26/2023] [Revised: 07/24/2023] [Accepted: 08/22/2023] [Indexed: 10/14/2023]
Abstract
BACKGROUND Multifocal ectopic Purkinje-related premature contractions (MEPPCs) are associated with SCN5A variants. However, it is not well understood why Purkinje fibers, but not ventricular myocardium, play a predominant role in arrhythmogenesis. OBJECTIVES This study sought to explore the underlying mechanisms of MEPPC. METHODS Whole-cell patch-clamp and molecular biology techniques were used in the present study. RESULTS Clinical data from one patient with R814W variant showed MEPPC syndrome, which is well responsive to amiodarone. Compared with canine ventricular myocytes, Purkinje cells (PCs) had significantly larger sodium current (INa), leftward shift of INa activation and inactivation curves, suggesting higher sodium channel excitability in PCs. Real-time polymerase chain reaction and Western blot analysis showed that the mRNA and protein expression of NaVβ1 and NaVβ3 was higher in canine Purkinje fibers than in ventricular myocardium. INa in heterologous Chinese hamster ovary cell expression system co-expressing NaV1.5 and NaVβ1/NaVβ3 exhibited similar biophysical properties of INa in PCs. R814W variant shifted INa activation in a hyperdepolarized direction, caused a larger window current, and generated an outward-gating pore current at depolarized voltages. Coexpression of NaVβ1/NaVβ3 with Nav1.5-R814W further left-shifted INa activation and caused an even larger window current and gating pore current, suggesting higher susceptibility of Purkinje fibers to R814W variant. Amiodarone inhibited INa, shifted its inactivation to more negative voltages, and significantly decreased the window current. CONCLUSIONS A higher expression of β1 and β3 subunits contributes to higher sodium channel excitability in cardiac Purkinje fibers, making them more susceptible to MEPPC.
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Affiliation(s)
- Wei Li
- Department of Cardiology, Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Chun-Xuan Wu
- Department of Cardiology, Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Jian-Wen Hou
- Department of Cardiology, Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Jian Sun
- Department of Cardiology, Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Qun-Shan Wang
- Department of Cardiology, Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Peng-Pai Zhang
- Department of Cardiology, Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yi Yu
- Department of Cardiology, Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Mei Yang
- Department of Cardiology, Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Mu Chen
- Department of Cardiology, Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Bin-Feng Mo
- Department of Cardiology, Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yue-Peng Wang
- Department of Cardiology, Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yi-Gang Li
- Department of Cardiology, Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China.
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Liang J, Luo S, Huang B. Case Report: SCN5A mutations in three young patients with sick sinus syndrome. Front Cardiovasc Med 2023; 10:1294197. [PMID: 38107266 PMCID: PMC10722160 DOI: 10.3389/fcvm.2023.1294197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Accepted: 11/17/2023] [Indexed: 12/19/2023] Open
Abstract
Background Sick Sinus Syndrome (SSS) is generally regarded as a degenerative disease with aging; however, genetic mutations have been confirmed to be associated with SSS. Among them, mutations in SCN5A are common in patients with SSS. We report three young SSS patients with SCN5A mutations at different sites that have not been previously reported in Asian patients. Case presentation The three patients were all young females who presented with symptoms of severe bradycardia and paroxysmal atrial flutter, for which two patients received ablation therapy. However, after ablation, Holter monitoring indicated a significant long cardiac arrest; therefore, the patients received pacemaker implantation. The three patients had familial SSS, and genetic testing was performed. Mutations were found in SCN5A at different sites in the three families. All three patients received pacemaker implantation, resulting in the symptoms of severe bradycardia disappearing. Conclusion SCN5A heterozygous mutations are common among patients clinically affected by SSS. Their causative role is confirmed by our data and by the co-occurrence of genetic arrhythmias among our patients. Genetic testing for SSS cannot be performed as a single gene panel because of feasible literature results, but in presence of familial and personal history of SSS in association with arrhythmias can provide clinically useful information.
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Affiliation(s)
| | - Suxin Luo
- Department of Cardiology, The First Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Bi Huang
- Department of Cardiology, The First Affiliated Hospital of Chongqing Medical University, Chongqing, China
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Wada Y. From Basic Cardiac Electrophysiology to Mechanism-Based Therapy in Ion Channelopathies. JACC Clin Electrophysiol 2023; 9:2491-2493. [PMID: 38151300 DOI: 10.1016/j.jacep.2023.11.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Revised: 11/04/2023] [Accepted: 11/04/2023] [Indexed: 12/29/2023]
Affiliation(s)
- Yuko Wada
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, USA.
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7
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Wauchop M, Rafatian N, Zhao Y, Chen W, Gagliardi M, Massé S, Cox BJ, Lai P, Liang T, Landau S, Protze S, Gao XD, Wang EY, Tung KC, Laksman Z, Lu RXZ, Keller G, Nanthakumar K, Radisic M, Backx PH. Maturation of iPSC-derived cardiomyocytes in a heart-on-a-chip device enables modeling of dilated cardiomyopathy caused by R222Q-SCN5A mutation. Biomaterials 2023; 301:122255. [PMID: 37651922 PMCID: PMC10942743 DOI: 10.1016/j.biomaterials.2023.122255] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Revised: 07/17/2023] [Accepted: 07/23/2023] [Indexed: 09/02/2023]
Abstract
To better understand sodium channel (SCN5A)-related cardiomyopathies, we generated ventricular cardiomyocytes from induced pluripotent stem cells obtained from a dilated cardiomyopathy patient harbouring the R222Q mutation, which is only expressed in adult SCN5A isoforms. Because the adult SCN5A isoform was poorly expressed, without functional differences between R222Q and control in both embryoid bodies and cell sheet preparations (cultured for 29-35 days), we created heart-on-a-chip biowires which promote myocardial maturation. Indeed, biowires expressed primarily adult SCN5A with R222Q preparations displaying (arrhythmogenic) short action potentials, altered Na+ channel biophysical properties and lower contractility compared to corrected controls. Comprehensive RNA sequencing revealed differential gene regulation between R222Q and control biowires in cellular pathways related to sarcoplasmic reticulum and dystroglycan complex as well as biological processes related to calcium ion regulation and action potential. Additionally, R222Q biowires had marked reductions in actin expression accompanied by profound sarcoplasmic disarray, without differences in cell composition (fibroblast, endothelial cells, and cardiomyocytes) compared to corrected biowires. In conclusion, we demonstrate that in addition to altering cardiac electrophysiology and Na+ current, the R222Q mutation also causes profound sarcomere disruptions and mechanical destabilization. Possible mechanisms for these observations are discussed.
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Affiliation(s)
- Marianne Wauchop
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, ON, M5S 1A8, Canada
| | - Naimeh Rafatian
- Division of Cardiology and Peter Munk Cardiac Center, University Health Network, Toronto, ON, M5G 1L7, Canada
| | - Yimu Zhao
- Toronto General Hospital Research Institute, Toronto, ON, M5G 2C4, Canada; Institute of Biomedical Engineering, University of Toronto, Toronto, ON, M5S 3G9, Canada
| | - Wenliang Chen
- Division of Cardiology and Peter Munk Cardiac Center, University Health Network, Toronto, ON, M5G 1L7, Canada; Department of Biology, York University, Toronto, ON, M3J 1P3, Canada
| | - Mark Gagliardi
- McEwen Stem Cell Institute, University Health Network, Toronto, ON, M5G 1L7, Canada
| | - Stéphane Massé
- Division of Cardiology and Peter Munk Cardiac Center, University Health Network, Toronto, ON, M5G 1L7, Canada; Toronto General Hospital Research Institute, Toronto, ON, M5G 2C4, Canada; The Hull Family Cardiac Fibrillation Management Laboratory, Toronto General Hospital, Toronto, ON, M5G 2C4, Canada
| | - Brian J Cox
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, ON, M5S 1A8, Canada; Department of Obstetrics and Gynaecology, Faculty of Medicine, University of Toronto, Toronto, ON, M5S 1A8, Canada
| | - Patrick Lai
- Division of Cardiology and Peter Munk Cardiac Center, University Health Network, Toronto, ON, M5G 1L7, Canada; Toronto General Hospital Research Institute, Toronto, ON, M5G 2C4, Canada; The Hull Family Cardiac Fibrillation Management Laboratory, Toronto General Hospital, Toronto, ON, M5G 2C4, Canada
| | - Timothy Liang
- Division of Cardiology and Peter Munk Cardiac Center, University Health Network, Toronto, ON, M5G 1L7, Canada; Toronto General Hospital Research Institute, Toronto, ON, M5G 2C4, Canada; The Hull Family Cardiac Fibrillation Management Laboratory, Toronto General Hospital, Toronto, ON, M5G 2C4, Canada
| | - Shira Landau
- Institute of Biomedical Engineering, University of Toronto, Toronto, ON, M5S 3G9, Canada
| | - Stephanie Protze
- McEwen Stem Cell Institute, University Health Network, Toronto, ON, M5G 1L7, Canada; Department of Molecular Genetics, University of Toronto, Toronto, ON, M5S 1A8, Canada
| | - Xiao Dong Gao
- Department of Biology, York University, Toronto, ON, M3J 1P3, Canada
| | - Erika Yan Wang
- Institute of Biomedical Engineering, University of Toronto, Toronto, ON, M5S 3G9, Canada
| | - Kelvin Chan Tung
- McEwen Stem Cell Institute, University Health Network, Toronto, ON, M5G 1L7, Canada
| | - Zachary Laksman
- Department of Medicine, University of British Columbia, Vancouver, BC, V6E 1M7, Canada
| | - Rick Xing Ze Lu
- Institute of Biomedical Engineering, University of Toronto, Toronto, ON, M5S 3G9, Canada
| | - Gordon Keller
- McEwen Stem Cell Institute, University Health Network, Toronto, ON, M5G 1L7, Canada; Department of Medical Biophysics, University of Toronto, Toronto, ON, M5G 1L7, Canada
| | - Kumaraswamy Nanthakumar
- Division of Cardiology and Peter Munk Cardiac Center, University Health Network, Toronto, ON, M5G 1L7, Canada; Toronto General Hospital Research Institute, Toronto, ON, M5G 2C4, Canada; The Hull Family Cardiac Fibrillation Management Laboratory, Toronto General Hospital, Toronto, ON, M5G 2C4, Canada.
| | - Milica Radisic
- Toronto General Hospital Research Institute, Toronto, ON, M5G 2C4, Canada; Institute of Biomedical Engineering, University of Toronto, Toronto, ON, M5S 3G9, Canada; Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, ON, Canada, M5S 3E5.
| | - Peter H Backx
- Division of Cardiology and Peter Munk Cardiac Center, University Health Network, Toronto, ON, M5G 1L7, Canada; Department of Biology, York University, Toronto, ON, M3J 1P3, Canada; Terrence Donnelly Centre for Cellular & Biomolecular Research, University of Toronto, Toronto, ON, M5S 3E1, Canada.
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Wong J, Peters S, Marwick TH. Phenotyping heart failure by genetics and associated conditions. Eur Heart J Cardiovasc Imaging 2023; 24:1293-1301. [PMID: 37279791 DOI: 10.1093/ehjci/jead125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Accepted: 05/26/2023] [Indexed: 06/08/2023] Open
Abstract
Heart failure is a highly heterogeneous disease, and genetic testing may allow phenotypic distinctions that are incremental to those obtainable from imaging. Advances in genetic testing have allowed for the identification of deleterious variants in patients with specific heart failure phenotypes (dilated cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy, and hypertrophic cardiomyopathy), and many of these have specific treatment implications. The diagnostic yield of genetic testing in heart failure is modest, and many rare variants are associated with incomplete penetrance and variable expressivity. Environmental factors and co-morbidities have a large role in the heterogeneity of the heart failure phenotype. Future endeavours should concentrate on the cumulative impact of genetic polymorphisms in the development of heart failure.
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Affiliation(s)
- Joshua Wong
- Baker Heart and Diabetes Institute and Department of Cardiometabolic Health, University of Melbourne, PO Box 6492, Melbourne, VIC 3004, Australia
| | - Stacey Peters
- Baker Heart and Diabetes Institute and Department of Cardiometabolic Health, University of Melbourne, PO Box 6492, Melbourne, VIC 3004, Australia
| | - Thomas H Marwick
- Baker Heart and Diabetes Institute and Department of Cardiometabolic Health, University of Melbourne, PO Box 6492, Melbourne, VIC 3004, Australia
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Ahangar AA, Elhanafy E, Blanton H, Li J. Mapping Structural Distribution and Gating-Property Impacts of Disease-Associated Missense Mutations in Voltage-Gated Sodium Channels. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.20.558623. [PMID: 37781633 PMCID: PMC10541146 DOI: 10.1101/2023.09.20.558623] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/03/2023]
Abstract
Thousands of voltage-gated sodium (Nav) channel variants contribute to a variety of disorders, including epilepsy, autism, cardiac arrhythmia, and pain disorders. Yet variant effects of more mutations remain unclear. The conventional gain-of-function (GoF) or loss-of-function (LoF) classifications is frequently employed to interpret of variant effects on function and guide precision therapy for sodium channelopathies. Our study challenges this binary classification by analyzing 525 mutations associated with 34 diseases across 366 electrophysiology studies, revealing that diseases with similar phenotypic effects can stem from unique molecular mechanisms. Our results show a high biophysical agreement (86%) between homologous disease-associated variants in different Nav genes, significantly surpassing the 60% phenotype (GoFo/LoFo) agreement among homologous mutants, suggesting the need for more nuanced disease categorization and treatment based on specific gating-property changes. Using UniProt data, we mapped over 2,400 disease-associated missense variants across nine human Nav channels and identified three clusters of mutation hotspots. Our findings indicate that mutations near the selectivity filter generally diminish the maximal current amplitude, while those in the fast inactivation region lean towards a depolarizing shift in half-inactivation voltage in steady-state activation, and mutations in the activation gate commonly enhance persistent current. In contrast to mutations in the PD, those within the VSD exhibit diverse impacts and subtle preferences on channel activity. This study shows great potential to enhance prediction accuracy for variant effects based on the structural context, laying the groundwork for targeted drug design in precision medicine.
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Affiliation(s)
- Amin Akbari Ahangar
- Department of Biomolecular Sciences, School of Pharmacy, University of Mississippi
| | - Eslam Elhanafy
- Department of Biomolecular Sciences, School of Pharmacy, University of Mississippi
| | - Hayden Blanton
- Department of Biomolecular Sciences, School of Pharmacy, University of Mississippi
| | - Jing Li
- Department of Biomolecular Sciences, School of Pharmacy, University of Mississippi
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10
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Calloe K, Magnusson HBD, Lildballe DL, Christiansen MK, Jensen HK. Multifocal ectopic purkinje-related premature contractions and related cardiomyopathy. Front Cardiovasc Med 2023; 10:1179018. [PMID: 37600057 PMCID: PMC10436533 DOI: 10.3389/fcvm.2023.1179018] [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: 03/03/2023] [Accepted: 07/24/2023] [Indexed: 08/22/2023] Open
Abstract
In the past 20 years, genetic variants in SCN5A encoding the cardiac voltage-gated sodium channel Nav1.5 have been linked to a range of inherited cardiac arrhythmias: variants resulting in loss-of-function of Nav1.5 have been linked to sick sinus syndrome, atrial stand still, atrial fibrillation (AF) impaired pulse generation, progressive and non-progressive conduction defects, the Brugada Syndrome (BrS), and sudden cardiac death. SCN5A variants causing increased sodium current during the plateau phase of the cardiac action potential is associated with Long QT Syndrome type 3 (LQTS3), Torsade de Pointes ventricular tachycardia and SCD. Recently, gain-of-function variants have been linked to complex electrical phenotypes, such as the Multifocal Ectopic Purkinje-related Premature Contractions (MEPPC) syndrome. MEPPC is a rare condition characterized by a high burden of premature atrial contractions (PACs) and/or premature ventricular contractions (PVCs) often accompanied by dilated cardiomyopathy (DCM). MEPPC is inherited in an autosomal dominant fashion with an almost complete penetrance. The onset is often in childhood. The link between SCN5A variants, MEPPC and DCM is currently not well understood, but amino acid substitutions resulting in gain-of-function of Nav1.5 or introduction of gating pore currents potentially play an important role. DCM patients with a MEPPC phenotype respond relatively poorly to standard heart failure medical therapy and catheter ablation as the PVCs originate from all parts of the fascicular Purkinje fiber network. Class 1c sodium channel inhibitors, notably flecainide, have a remarkable positive effect on the ectopic burden and the associated cardiomyopathy. This highlights the importance of genetic screening of DCM patients to identify patients with SCN5A variants associated with MEPPC. Here we review the MEPPC phenotype, MEPPC-SCN5A associated variants, and pathogenesis as well as treatment options.
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Affiliation(s)
- Kirstine Calloe
- Department of Veterinary and Animal Sciences, University of Copenhagen, Frederiksberg, Denmark
| | - Helena B. D. Magnusson
- Department of Veterinary and Animal Sciences, University of Copenhagen, Frederiksberg, Denmark
| | | | | | - Henrik Kjærulf Jensen
- Department of Cardiology, Aarhus University Hospital, Aarhus, Denmark
- Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
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11
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Calloe K, Geryk M, Freude K, Treat JA, Vold VA, Frederiksen HRS, Broendberg AK, Frederiksen TC, Jensen HK, Cordeiro JM. The G213D variant in Nav1.5 alters sodium current and causes an arrhythmogenic phenotype resulting in a multifocal ectopic Purkinje-related premature contraction phenotype in human-induced pluripotent stem cell-derived cardiomyocytes. Europace 2022; 24:2015-2027. [PMID: 35726875 DOI: 10.1093/europace/euac090] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Accepted: 05/12/2022] [Indexed: 12/14/2022] Open
Abstract
AIMS Variants in SCN5A encoding Nav1.5 are associated with cardiac arrhythmias. We aimed to determine the mechanism by which c.638G>A in SCNA5 resulting in p.Gly213Asp (G213D) in Nav1.5 altered Na+ channel function and how flecainide corrected the defect in a family with multifocal ectopic Purkinje-related premature contractions (MEPPC)-like syndrome. METHODS AND RESULTS Five patients carrying the G213D variant were treated with flecainide. Gating pore currents were evaluated in Xenopus laevis oocytes. The 638G>A SCN5A variant was introduced to human-induced pluripotent stem cell (hiPSC) by CRISPR-Cas9 gene editing and subsequently differentiated to cardiomyocytes (hiPSC-CM). Action potentials and sodium currents were measured in the absence and presence of flecainide. Ca2+ transients were measured by confocal microscopy. The five patients exhibited premature atrial and ventricular contractions which were suppressed by flecainide treatment. G213D induced gating pore current at potentials negative to -50 mV. Voltage-clamp analysis in hiPSC-CM revealed the activation threshold of INa was shifted in the hyperpolarizing direction resulting in a larger INa window current. The G213D hiPSC-CMs had faster beating rates compared with wild-type and frequently showed Ca2+ waves and alternans. Flecainide applied to G213D hiPSC-CMs decreased window current by shifting the steady-state inactivation curve and slowed the beating rate. CONCLUSION The G213D variant in Nav1.5 induced gating pore currents and increased window current. The changes in INa resulted in a faster beating rate and Ca2+ transient dysfunction. Flecainide decreased window current and inhibited INa, which is likely responsible for the therapeutic effectiveness of flecainide in MEPPC patients carrying the G213D variant.
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Affiliation(s)
- Kirstine Calloe
- Section for Pathobiological Sciences, Department of Veterinary and Animal Sciences, University of Copenhagen, Dyrlaegevej 100 DK-1870 Frederiksberg, Denmark
| | - Michelle Geryk
- Section for Pathobiological Sciences, Department of Veterinary and Animal Sciences, University of Copenhagen, Dyrlaegevej 100 DK-1870 Frederiksberg, Denmark
| | - Kristine Freude
- Section for Pathobiological Sciences, Department of Veterinary and Animal Sciences, University of Copenhagen, Dyrlaegevej 100 DK-1870 Frederiksberg, Denmark
| | - Jacqueline A Treat
- Department of Experimental Cardiology, Masonic Medical Research Institute, 2150 Bleecker Street, Utica, NY 13501, USA
| | - Victoria A Vold
- Section for Pathobiological Sciences, Department of Veterinary and Animal Sciences, University of Copenhagen, Dyrlaegevej 100 DK-1870 Frederiksberg, Denmark
| | - Henriette Reventlow S Frederiksen
- Section for Pathobiological Sciences, Department of Veterinary and Animal Sciences, University of Copenhagen, Dyrlaegevej 100 DK-1870 Frederiksberg, Denmark
| | | | - Tanja Charlotte Frederiksen
- Department of Cardiology, Aarhus University Hospital, DK-8200 Aarhus N, Denmark.,Department of Clinical Medicine, Aarhus University, DK-8200 Aarhus N, Denmark
| | - Henrik K Jensen
- Department of Cardiology, Aarhus University Hospital, DK-8200 Aarhus N, Denmark.,Department of Clinical Medicine, Aarhus University, DK-8200 Aarhus N, Denmark
| | - Jonathan M Cordeiro
- Department of Experimental Cardiology, Masonic Medical Research Institute, 2150 Bleecker Street, Utica, NY 13501, USA
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12
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Cojocaru C, Penela D, Berruezo A, Vatasescu R. Mechanisms, time course and predictability of premature ventricular contractions cardiomyopathy-an update on its development and resolution. Heart Fail Rev 2022; 27:1639-1651. [PMID: 34510326 DOI: 10.1007/s10741-021-10167-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 08/23/2021] [Indexed: 01/05/2023]
Abstract
Frequent premature ventricular contractions (PVCs) associated left ventricular systolic dysfunction (LVSD) is a well-known clinical scenario and numerous predictors for cardiomyopathy (CMP) development have been already thoroughly described. It may present as a "pure" form of dissynchrony-induced cardiomyopathy or it may be an aggravating component of a multifactorial structural heart disease. However, the precise risk to develop PVC-induced CMP (which would allow for tailored-patient monitoring and/or early treatment) and the degree of CMP reversibility after PVC suppression/elimination (which may permit appropriate candidate selection for therapy) are unclear. Moreover, there is limited data regarding the time course of CMP development and resolution after arrhythmia suppression. Even less known are the other components of PVC-induced CMP, such as right ventricular (RV) and atrial myopathies. This review targets to synthetize the most recent information in this regard and bring a deeper understanding of this heart failure scenario. The mechanisms, time course (both in experimental models and clinical experiences) and predictors of reverse-remodelling after arrhythmia suppression are described. The novel experience hereby presented may aid everyday clinical practice, promoting a new paradigm involving more complex, multi-level and multi-modality evaluation and possible earlier intervention at least in some patient subsets.
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Affiliation(s)
- C Cojocaru
- Clinical Emergency Hospital, Bucharest, Romania
| | - D Penela
- Heart Institute, Teknon Medical Centre, Barcelona, Spain
| | - Antonio Berruezo
- Medical Centre Teknon, Grupo Quironsalud, Barcelona, Spain. .,Heart Institute, Teknon Medical Centre, Barcelona, Spain.
| | - R Vatasescu
- Clinical Emergency Hospital, Bucharest, Romania
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13
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Lukas Laws J, Lancaster MC, Ben Shoemaker M, Stevenson WG, Hung RR, Wells Q, Marshall Brinkley D, Hughes S, Anderson K, Roden D, Stevenson LW. Arrhythmias as Presentation of Genetic Cardiomyopathy. Circ Res 2022; 130:1698-1722. [PMID: 35617362 PMCID: PMC9205615 DOI: 10.1161/circresaha.122.319835] [Citation(s) in RCA: 29] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
There is increasing evidence regarding the prevalence of genetic cardiomyopathies, for which arrhythmias may be the first presentation. Ventricular and atrial arrhythmias presenting in the absence of known myocardial disease are often labelled as idiopathic, or lone. While ventricular arrhythmias are well-recognized as presentation for arrhythmogenic cardiomyopathy in the right ventricle, the scope of arrhythmogenic cardiomyopathy has broadened to include those with dominant left ventricular involvement, usually with a phenotype of dilated cardiomyopathy. In addition, careful evaluation for genetic cardiomyopathy is also warranted for patients presenting with frequent premature ventricular contractions, conduction system disease, and early onset atrial fibrillation, in which most detected genes are in the cardiomyopathy panels. Sudden death can occur early in the course of these genetic cardiomyopathies, for which risk is not adequately tracked by left ventricular ejection fraction. Only a few of the cardiomyopathy genotypes implicated in early sudden death are recognized in current indications for implantable cardioverter defibrillators which otherwise rely upon a left ventricular ejection fraction ≤0.35 in dilated cardiomyopathy. The genetic diagnoses impact other aspects of clinical management such as exercise prescription and pharmacological therapy of arrhythmias, and new therapies are coming into clinical investigation for specific genetic cardiomyopathies. The expansion of available genetic information and implications raises new challenges for genetic counseling, particularly with the family member who has no evidence of a cardiomyopathy phenotype and may face a potentially negative impact of a genetic diagnosis. Discussions of risk for both probands and relatives need to be tailored to their numeric literacy during shared decision-making. For patients presenting with arrhythmias or cardiomyopathy, extension of genetic testing and its implications will enable cascade screening, intervention to change the trajectory for specific genotype-phenotype profiles, and enable further development and evaluation of emerging targeted therapies.
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Affiliation(s)
- J Lukas Laws
- Division of Cardiovascular Medicine, Vanderbilt Heart and Vascular Institute, Vanderbilt University Medical Center, Nashville, TN
| | - Megan C Lancaster
- Division of Cardiovascular Medicine, Vanderbilt Heart and Vascular Institute, Vanderbilt University Medical Center, Nashville, TN
| | - M Ben Shoemaker
- Division of Cardiovascular Medicine, Vanderbilt Heart and Vascular Institute, Vanderbilt University Medical Center, Nashville, TN
| | - William G Stevenson
- Division of Cardiovascular Medicine, Vanderbilt Heart and Vascular Institute, Vanderbilt University Medical Center, Nashville, TN
| | - Rebecca R Hung
- Division of Cardiovascular Medicine, Vanderbilt Heart and Vascular Institute, Vanderbilt University Medical Center, Nashville, TN
| | - Quinn Wells
- Division of Cardiovascular Medicine, Vanderbilt Heart and Vascular Institute, Vanderbilt University Medical Center, Nashville, TN
| | - D Marshall Brinkley
- Division of Cardiovascular Medicine, Vanderbilt Heart and Vascular Institute, Vanderbilt University Medical Center, Nashville, TN
| | - Sean Hughes
- Division of Cardiovascular Medicine, Vanderbilt Heart and Vascular Institute, Vanderbilt University Medical Center, Nashville, TN
| | - Katherine Anderson
- Division of Cardiovascular Medicine, Vanderbilt Heart and Vascular Institute, Vanderbilt University Medical Center, Nashville, TN
| | - Dan Roden
- Division of Cardiovascular Medicine, Vanderbilt Heart and Vascular Institute, Vanderbilt University Medical Center, Nashville, TN
| | - Lynne W Stevenson
- Division of Cardiovascular Medicine, Vanderbilt Heart and Vascular Institute, Vanderbilt University Medical Center, Nashville, TN
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14
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Peters S, Thompson BA, Perrin M, James P, Zentner D, Kalman JM, Vandenberg JI, Fatkin D. Arrhythmic Phenotypes Are a Defining Feature of Dilated Cardiomyopathy-Associated SCN5A Variants: A Systematic Review. CIRCULATION. GENOMIC AND PRECISION MEDICINE 2022; 15:e003432. [PMID: 34949099 DOI: 10.1161/circgen.121.003432] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
BACKGROUND Variants in the SCN5A gene, that encodes the cardiac sodium channel, Nav1.5, are associated with a highly arrhythmogenic form of dilated cardiomyopathy (DCM). Our aim was to review the phenotypes, natural history, functional effects, and treatment outcomes of DCM-associated rare SCN5A variants. METHODS A systematic review of reported DCM-associated rare SCN5A variants was undertaken using PubMed and Embase. RESULTS Eighteen SCN5A rare variants in 29 families with DCM (173 affected individuals) were identified. Eleven variants had undergone experimental evaluation, with 7 of these resulting in increased sustained current flow during the action potential (eg, increased window current) and at resting membrane potentials (eg, creation of a new gating pore current). These variants were located in transmembrane voltage-sensing domains and had a consistent phenotype characterized by frequent multifocal narrow and broad complex ventricular premature beats (VPB; 72% of affected relatives), ventricular arrhythmias (33%), atrial arrhythmias (32%), sudden cardiac death (13%), and DCM (56%). This VPB-predominant phenotype was not seen with 1 variant that increased late sodium current, or with variants that reduced peak current density or had mixed effects. In the latter groups, affected individuals mainly showed sinus node dysfunction, conduction defects, and atrial arrhythmias, with infrequent VPB and ventricular arrhythmias. DCM did not occur in the absence of arrhythmias for any variant. Twelve studies (23 total patients) reported treatment success in the VPB-predominant cardiomyopathy using sodium channel-blocking drug therapy. CONCLUSIONS SCN5A variants can present with a diverse spectrum of primary arrhythmic features. A majority of DCM-associated variants cause a multifocal VPB-predominant cardiomyopathy that is reversible with sodium channel blocking drug therapy. Early recognition of the distinctive phenotype and prompt genetic testing to identify variant carriers are needed. Our findings have implications for interpretation and management of SCN5A variants found in DCM patients with and without arrhythmias.
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Affiliation(s)
- Stacey Peters
- Department of Cardiology (S.P., M.P., D.Z., J.M.K.), Royal Melbourne Hospital
- Department of Genomic Medicine (S.P., B.A.T., M.P., P.J., D.Z.), Royal Melbourne Hospital
- Department of Medicine, University of Melbourne (S.P., P.J., D.Z., J.M.K.)
| | - Bryony A Thompson
- Department of Genomic Medicine (S.P., B.A.T., M.P., P.J., D.Z.), Royal Melbourne Hospital
- Department of Pathology (B.A.T.), Royal Melbourne Hospital
| | - Mark Perrin
- Department of Genomic Medicine (S.P., B.A.T., M.P., P.J., D.Z.), Royal Melbourne Hospital
| | - Paul James
- Department of Genomic Medicine (S.P., B.A.T., M.P., P.J., D.Z.), Royal Melbourne Hospital
- Department of Medicine, University of Melbourne (S.P., P.J., D.Z., J.M.K.)
- Familial Cancer Centre, Peter MacCallum Centre, Melbourne, Victoria (P.J.)
| | - Dominica Zentner
- Department of Genomic Medicine (S.P., B.A.T., M.P., P.J., D.Z.), Royal Melbourne Hospital
- Department of Medicine, University of Melbourne (S.P., P.J., D.Z., J.M.K.)
| | - Jonathan M Kalman
- Department of Medicine, University of Melbourne (S.P., P.J., D.Z., J.M.K.)
| | - Jamie I Vandenberg
- Molecular Cardiology Division, Victor Chang Cardiac Research Institute (J.I.V., D.F.)
- St. Vincent's Clinical School, Faculty of Medicine, UNSW Sydney (J.I.V., D.F.)
| | - Diane Fatkin
- Molecular Cardiology Division, Victor Chang Cardiac Research Institute (J.I.V., D.F.)
- St. Vincent's Clinical School, Faculty of Medicine, UNSW Sydney (J.I.V., D.F.)
- Cardiology Department, St. Vincent's Hospital, Sydney, New South Wales, Australia (D.F.)
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15
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Long-Term Efficacy and Safety of Sodium Channel Antagonists in Patients With p.R222Q SCN5A-Related Arrhythmic Dilated Cardiomyopathy. JACC Clin Electrophysiol 2021; 7:126-128. [PMID: 33478705 DOI: 10.1016/j.jacep.2020.09.023] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Accepted: 09/14/2020] [Indexed: 11/24/2022]
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16
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Fatkin D, Calkins H, Elliott P, James CA, Peters S, Kovacic JC. Contemporary and Future Approaches to Precision Medicine in Inherited Cardiomyopathies: JACC Focus Seminar 3/5. J Am Coll Cardiol 2021; 77:2551-2572. [PMID: 34016267 DOI: 10.1016/j.jacc.2020.12.072] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Revised: 12/10/2020] [Accepted: 12/18/2020] [Indexed: 01/02/2023]
Abstract
Inherited cardiomyopathies are commonly occurring myocardial disorders that are associated with substantial morbidity and mortality. Clinical management strategies have focused on treatment of heart failure and arrhythmic complications in symptomatic patients according to standardized guidelines. Clinicians are now being urged to implement precision medicine, but what does this involve? Advances in understanding of the genetic underpinnings of inherited cardiomyopathies have brought new possibilities for interventions that are tailored to genes, specific variants, or downstream mechanisms. However, the phenotypic variability that can occur with any given pathogenic variant suggests that factors other than single driver gene mutations are often involved. This is propelling a new imperative to elucidate the nuanced ways in which individual combinations of genetic variation, comorbidities, and lifestyle may influence cardiomyopathy phenotypes. Here, Part 3 of a 5-part precision medicine Focus Seminar series reviews the current status and future opportunities for precision medicine in the inherited cardiomyopathies.
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Affiliation(s)
- Diane Fatkin
- Victor Chang Cardiac Research Institute, Darlinghurst, New South Wales, Australia; St. Vincent's Clinical School, Faculty of Medicine, UNSW Sydney, Kensington, New South Wales, Australia; Cardiology Department, St. Vincent's Hospital, Darlinghurst, New South Wales, Australia.
| | - Hugh Calkins
- Division of Cardiology, Johns Hopkins School of Medicine, Baltimore, Maryland, USA
| | - Perry Elliott
- Institute of Cardiovascular Sciences, University College London, London, United Kingdom; Barts Heart Centre, St. Bartholomew's Hospital, London, United Kingdom
| | - Cynthia A James
- Division of Cardiology, Johns Hopkins School of Medicine, Baltimore, Maryland, USA
| | - Stacey Peters
- Departments of Cardiology and Genomic Medicine, Royal Melbourne Hospital, Melbourne, Victoria, Australia; Department of Medicine, University of Melbourne, Melbourne, Victoria, Australia
| | - Jason C Kovacic
- Victor Chang Cardiac Research Institute, Darlinghurst, New South Wales, Australia; St. Vincent's Clinical School, Faculty of Medicine, UNSW Sydney, Kensington, New South Wales, Australia; Cardiology Department, St. Vincent's Hospital, Darlinghurst, New South Wales, Australia; The Zena and Michael A. Wiener Cardiovascular Institute, Icahn School of Medicine at Mount Sinai, New York, New York, USA.
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17
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Leventopoulos G, Perperis A, Karelas D, Almpanis G. You cannot ablate the Lernaean Hydra: SCN5A mutation in a patient with multifocal ectopic Purkinje-related premature contractions syndrome treated with Flecainide and an implant of a subcutaneous defibrillator—a case report. Eur Heart J Case Rep 2021; 5:ytab158. [PMID: 33959699 PMCID: PMC8086419 DOI: 10.1093/ehjcr/ytab158] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2020] [Revised: 08/28/2020] [Accepted: 04/12/2021] [Indexed: 12/19/2022]
Abstract
Background SCN5A mutations may present with different clinical phenotypes such as Brugada syndrome, long QT3 syndrome, sick sinus syndrome, atrial fibrillation, dilated cardiomyopathy, and the least known multifocal ectopic Purkinje-related premature contractions syndrome. Case summary We report a case of a 29-year-old woman with palpitations due to multifocal premature ventricular complexes (PVCs) and a family history of sudden death. The previous electrophysiological study had shown that PVCs arose from Purkinje fibres but catheter ablation was unsuccessful. Cardiac magnetic resonance (CMR) imaging demonstrated non-ischaemic areas of subendocardial fibrosis at multiple left ventricular (LV) segments with concomitant dilatation and mild systolic impairment. Amiodarone suppressed the ectopy but caused hyperthyroidism. Due to recent pregnancy, she received no antiarrhythmics which resulted in PVC burden increase and further deterioration of the ejection fraction (EF). After gestation, amiodarone was reinitiated and switched to flecainide after implantation of a subcutaneous defibrillator as a safety net. At follow-up, LV function had almost normalized. Genetic analysis confirmed an SCN5A mutation. Discussion Multifocal ectopic Purkinje-related premature contractions syndrome is associated with SCN5A mutation which in our case (R222Q) is the most common described. Flecainide can be an appropriate treatment option when ablation is ineffective. Defibrillator—even a subcutaneous type—could be implanted in cases of LV dysfunction or scar. PVCs suppression by flecainide and restoration of EF implies an arrhythmia—induced mechanism of LV impairment.
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18
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Nakajima T, Kaneko Y, Dharmawan T, Kurabayashi M. Role of the voltage sensor module in Na v domain IV on fast inactivation in sodium channelopathies: The implication of closed-state inactivation. Channels (Austin) 2020; 13:331-343. [PMID: 31357904 PMCID: PMC6713248 DOI: 10.1080/19336950.2019.1649521] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The segment 4 (S4) voltage sensor in voltage-gated sodium channels (Navs) have domain-specific functions, and the S4 segment in domain DIV (DIVS4) plays a key role in the activation and fast inactivation processes through the coupling of arginine residues in DIVS4 with residues of putative gating charge transfer center (pGCTC) in DIVS1-3. In addition, the first four arginine residues (R1-R4) in Nav DIVS4 have position-specific functions in the fast inactivation process, and mutations in these residues are associated with diverse phenotypes of Nav-related diseases (sodium channelopathies). R1 and R2 mutations commonly display a delayed fast inactivation, causing a gain-of-function, whereas R3 and R4 mutations commonly display a delayed recovery from inactivation and profound use-dependent current attenuation, causing a severe loss-of-function. In contrast, mutations of residues of pGCTC in Nav DIVS1-3 can also alter fast inactivation. Such alterations in fast inactivation may be caused by disrupted interactions of DIVS4 with DIVS1-3. Despite fast inactivation of Navs occurs from both the open-state (open-state inactivation; OSI) and closed state (closed-state inactivation; CSI), changes in CSI have received considerably less attention than those in OSI in the pathophysiology of sodium channelopathies. CSI can be altered by mutations of arginine residues in DIVS4 and residues of pGCTC in Navs, and altered CSI can be an underlying primary biophysical defect of sodium channelopathies. Therefore, CSI should receive focus in order to clarify the pathophysiology of sodium channelopathies.
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Affiliation(s)
- Tadashi Nakajima
- a Department of Cardiovascular Medicine, Gunma University Graduate School of Medicine , Maebashi , Gunma , Japan
| | - Yoshiaki Kaneko
- a Department of Cardiovascular Medicine, Gunma University Graduate School of Medicine , Maebashi , Gunma , Japan
| | - Tommy Dharmawan
- a Department of Cardiovascular Medicine, Gunma University Graduate School of Medicine , Maebashi , Gunma , Japan
| | - Masahiko Kurabayashi
- a Department of Cardiovascular Medicine, Gunma University Graduate School of Medicine , Maebashi , Gunma , Japan
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19
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Doisne N, Waldmann V, Redheuil A, Waintraub X, Fressart V, Ader F, Fossé L, Hidden-Lucet F, Gandjbakhch E, Neyroud N. A novel gain-of-function mutation in SCN5A responsible for multifocal ectopic Purkinje-related premature contractions. Hum Mutat 2020; 41:850-859. [PMID: 31930659 DOI: 10.1002/humu.23981] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Revised: 12/13/2019] [Accepted: 01/02/2020] [Indexed: 12/19/2022]
Abstract
Recently, four SCN5A mutations have been associated with Multifocal Ectopic Purkinje-related Premature Contractions (MEPPC), a rare cardiac syndrome combining polymorphic ventricular arrhythmia with dilated cardiomyopathy (DCM). Here, we identified a novel heterozygous mutation in SCN5A (c.611C>A, pAla204Glu) in a young woman presenting with polymorphic premature ventricular contractions (PVCs) and DCM. After failure of antiarrhythmic drugs and an attempt of radiofrequency catheter ablation showing three exit-sites of PVCs, all with presystolic Purkinje potentials, a treatment by hydroquinidine was tried, leading to an immediate and spectacular disappearance of all PVCs and normalization of cardiac function. Electrophysiological studies showed that Nav 1.5-A204E mutant channels exhibited a significant leftward shift of 8 mV of the activation curve, leading to a larger hyperpolarized window current when compared to wild-type. Action potential modeling using Purkinje fiber and ventricular cell models predicted an arrhythmogenic effect predominant in Purkinje fibers for the A204E mutation. Comparison with other MEPPC-associated Nav 1.5 mutations revealed a common electrophysiological pattern of abnormal voltage-dependence of activation leading to a larger hyperpolarized window current as a shared biophysical mechanism of this syndrome. These features of the mutant sodium channels are likely to be responsible for the hyperexcitability of the fascicular-Purkinje system observed in patients with MEPPC.
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Affiliation(s)
- Nicolas Doisne
- Faculté de Médecine, Sorbonne Université, Paris, France.,INSERM, UMR_S1166, Hôpital Pitié-Salpêtrière, Paris, France.,ICAN, Institute of Cardiometabolism and Nutrition, Paris, France
| | - Victor Waldmann
- Département de Cardiologie, Hôpital Pitié-Salpêtrière, Assistance Publique-Hôpitaux de Paris, Paris, France
| | - Alban Redheuil
- Faculté de Médecine, Sorbonne Université, Paris, France.,ICAN, Institute of Cardiometabolism and Nutrition, Paris, France.,Département d'Imagerie Cardiovasculaire, Hôpital Pitié-Salpêtrière, Assistance Publique-Hôpitaux de Paris, Paris, France
| | - Xavier Waintraub
- ICAN, Institute of Cardiometabolism and Nutrition, Paris, France.,Département de Cardiologie, Hôpital Pitié-Salpêtrière, Assistance Publique-Hôpitaux de Paris, Paris, France
| | - Véronique Fressart
- Faculté de Médecine, Sorbonne Université, Paris, France.,INSERM, UMR_S1166, Hôpital Pitié-Salpêtrière, Paris, France.,ICAN, Institute of Cardiometabolism and Nutrition, Paris, France.,Département de Biochimie métabolique, Cardiogénétique, Hôpital Pitié-Salpêtrière, Assistance Publique-Hôpitaux de Paris, Paris, France
| | - Flavie Ader
- Faculté de Médecine, Sorbonne Université, Paris, France.,INSERM, UMR_S1166, Hôpital Pitié-Salpêtrière, Paris, France.,ICAN, Institute of Cardiometabolism and Nutrition, Paris, France.,Département de Biochimie métabolique, Cardiogénétique, Hôpital Pitié-Salpêtrière, Assistance Publique-Hôpitaux de Paris, Paris, France
| | - Lucie Fossé
- Faculté de Médecine, Sorbonne Université, Paris, France.,INSERM, UMR_S1166, Hôpital Pitié-Salpêtrière, Paris, France
| | - Françoise Hidden-Lucet
- ICAN, Institute of Cardiometabolism and Nutrition, Paris, France.,Département de Cardiologie, Hôpital Pitié-Salpêtrière, Assistance Publique-Hôpitaux de Paris, Paris, France
| | - Estelle Gandjbakhch
- Faculté de Médecine, Sorbonne Université, Paris, France.,INSERM, UMR_S1166, Hôpital Pitié-Salpêtrière, Paris, France.,ICAN, Institute of Cardiometabolism and Nutrition, Paris, France.,Département de Cardiologie, Hôpital Pitié-Salpêtrière, Assistance Publique-Hôpitaux de Paris, Paris, France
| | - Nathalie Neyroud
- Faculté de Médecine, Sorbonne Université, Paris, France.,INSERM, UMR_S1166, Hôpital Pitié-Salpêtrière, Paris, France.,ICAN, Institute of Cardiometabolism and Nutrition, Paris, France
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20
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Fatkin D, Huttner IG, Kovacic JC, Seidman J, Seidman CE. Precision Medicine in the Management of Dilated Cardiomyopathy. J Am Coll Cardiol 2019; 74:2921-2938. [DOI: 10.1016/j.jacc.2019.10.011] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Revised: 09/25/2019] [Accepted: 10/10/2019] [Indexed: 01/16/2023]
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21
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Pang PD, Alsina KM, Cao S, Koushik AB, Wehrens XHT, Cooper TA. CRISPR -Mediated Expression of the Fetal Scn5a Isoform in Adult Mice Causes Conduction Defects and Arrhythmias. J Am Heart Assoc 2019; 7:e010393. [PMID: 30371314 PMCID: PMC6404881 DOI: 10.1161/jaha.118.010393] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Background The sodium channel, Nav1.5, encoded by SCN5A, undergoes developmentally regulated splicing from inclusion of exon 6A in the fetal heart to exon 6B in adults. These mutually exclusive exons differ in 7 amino acids altering the electrophysiological properties of the Nav1.5 channel. In myotonic dystrophy type 1, SCN5A is mis‐spliced such that the fetal pattern of exon 6A inclusion is detected in adult hearts. Cardiac manifestations of myotonic dystrophy type 1 include conduction defects and arrhythmias and are the second‐leading cause of death. Methods and Results This work aimed to determine the impact of SCN5A mis‐splicing on cardiac function. We used clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR‐associated protein 9 (Cas9) to delete Scn5a exon 6B in mice, thereby redirecting splicing toward exon 6A. These mice exhibit prolonged PR and QRS intervals, slowed conduction velocity, extended action potential duration, and are highly susceptible to arrhythmias. Conclusions Our findings highlight a nonmutational pathological mechanism of arrhythmias and conduction defects as a result of mis‐splicing of the predominant cardiac sodium channel. Animals homozygous for the deleted exon express only the fetal isoform and have more‐severe phenotypes than heterozygotes that also express the adult isoform. This observation is directly relevant to myotonic dystrophy type 1, and possibly pathological arrhythmias, in which individuals differ with regard to the ratios of the isoforms expressed.
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Affiliation(s)
- Paul D Pang
- 1 Department of Molecular Physiology & Biophysics Baylor College of Medicine Houston TX.,2 Department of Pathology & Immunology Baylor College of Medicine Houston TX.,3 Integrative Molecular and Biomedical Sciences Program Baylor College of Medicine Houston TX
| | - Katherina M Alsina
- 1 Department of Molecular Physiology & Biophysics Baylor College of Medicine Houston TX.,3 Integrative Molecular and Biomedical Sciences Program Baylor College of Medicine Houston TX
| | - Shuyi Cao
- 1 Department of Molecular Physiology & Biophysics Baylor College of Medicine Houston TX
| | - Amrita B Koushik
- 2 Department of Pathology & Immunology Baylor College of Medicine Houston TX
| | - Xander H T Wehrens
- 1 Department of Molecular Physiology & Biophysics Baylor College of Medicine Houston TX.,3 Integrative Molecular and Biomedical Sciences Program Baylor College of Medicine Houston TX.,5 Department of Medicine Baylor College of Medicine Houston TX.,6 Department of Pediatrics Baylor College of Medicine Houston TX.,7 Center for Space Medicine Baylor College of Medicine Houston TX.,8 Cardiovascular Research Institute Baylor College of Medicine Houston TX
| | - Thomas A Cooper
- 1 Department of Molecular Physiology & Biophysics Baylor College of Medicine Houston TX.,2 Department of Pathology & Immunology Baylor College of Medicine Houston TX.,3 Integrative Molecular and Biomedical Sciences Program Baylor College of Medicine Houston TX.,4 Department of Molecular & Cellular Biology Baylor College of Medicine Houston TX.,8 Cardiovascular Research Institute Baylor College of Medicine Houston TX
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Daniel LL, Yang T, Kroncke B, Hall L, Stroud D, Roden DM. SCN5A variant R222Q generated abnormal changes in cardiac sodium current and action potentials in murine myocytes and Purkinje cells. Heart Rhythm 2019; 16:1676-1685. [PMID: 31125670 PMCID: PMC6825529 DOI: 10.1016/j.hrthm.2019.05.017] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Indexed: 12/19/2022]
Abstract
BACKGROUND The cardiac sodium channel (SCN5A) mutation R222Q neutralizes a positive charge in the domain I voltage sensor. Mutation carriers display very frequent ectopy and dilated cardiomyopathy. OBJECTIVES To describe the effect of SCN5A R222Q on murine myocyte and Purkinje fiber electrophysiology, and identify underlying mechanisms. METHODS We generated mice carrying humanized wild-type (H) and mutant (RQ) SCN5A channels. We characterized whole-heart and isolated ventricular and Purkinje myocyte properties. RESULTS RQ/RQ mice were not viable. INa from RQ/H ventricular myocytes displayed increased "window current" and hyperpolarizing shifts in both inactivation and activation compared to H/H, as previously reported in heterologous expression systems. Surprisingly, action potentials were markedly abbreviated in RQ/H myocytes (action potential durations at 90% repolarization: 12.6 ± 1.3 ms vs 29.1 ± 1.0 ms in H/H, P < .01, n = 10 each). We identified a large [K+]o-dependent outward gating pore current in RQ/H but not H/H myocytes, and decreasing [K+]o elicited early afterdepolarizations (EADs) and triggered activity in isolated myocytes and ectopic beats in whole hearts. Further, RQ/H Purkinje cells displayed striking, consistent low-voltage EADs. In vivo, however, RQ/H mice displayed little ectopy and contractile function was normal. CONCLUSION While SCN5A R222Q increases plateau inward sodium current, action potentials were unexpectedly shortened, likely reflecting an outward gating-pore current. Low extracellular potassium increased this pore current, and was arrhythmogenic in vitro and ex vivo.
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Affiliation(s)
- Laura L Daniel
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee; Department of Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Tao Yang
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee; Department of Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Brett Kroncke
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee; Department of Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Lynn Hall
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Dina Stroud
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Dan M Roden
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee; Department of Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee; Department of Biomedical Informatics, Vanderbilt University Medical Center, Nashville, Tennessee.
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Wilde AA, Garan H, Boyden PA. Role of the Purkinje system in heritable arrhythmias. Heart Rhythm 2019; 16:1121-1126. [DOI: 10.1016/j.hrthm.2019.01.034] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Indexed: 12/28/2022]
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24
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Peters S, Kumar S, Elliott P, Kalman JM, Fatkin D. Arrhythmic Genotypes in Familial Dilated Cardiomyopathy: Implications for Genetic Testing and Clinical Management. Heart Lung Circ 2019; 28:31-38. [DOI: 10.1016/j.hlc.2018.09.010] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Accepted: 09/23/2018] [Indexed: 11/30/2022]
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25
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Zakrzewska-Koperska J, Franaszczyk M, Bilińska Z, Truszkowska G, Karczmarz M, Szumowski Ł, Zieliński T, Płoski R, Bilińska M. Rapid and effective response of the R222Q SCN5A to quinidine treatment in a patient with Purkinje-related ventricular arrhythmia and familial dilated cardiomyopathy: a case report. BMC MEDICAL GENETICS 2018; 19:94. [PMID: 29871609 PMCID: PMC5989373 DOI: 10.1186/s12881-018-0599-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/29/2017] [Accepted: 05/01/2018] [Indexed: 11/13/2022]
Abstract
Background Mutations of the SCN5A gene are reported in 2-4% of patients with dilated cardiomyopathy (DCM). In such cases, DCM is associated with different rhythm disturbances such as the multifocal ectopic Purkinje-related premature contractions and atrial fibrillation. Arrhythmia often occurs at a young age and is the first symptom of heart disease. Case presentation We present the case of 55-year old male with a 30-year history of heart failure (HF) in the course of familial DCM and complex ventricular tachyarrhythmias, which constituted 50-80% of the whole rhythm. The patient was qualified for heart transplantation because of the increasing symptoms of HF. We revealed the heterozygotic R222Q mutation in SCN5A by means of whole exome sequencing. After the quinidine treatment, a rapid and significant reduction of ventricular tachyarrhythmias and an improvement in the myocardial function were observed and this effect remained constant in the 2.5-year follow-up. This effect was observed even in the presence of concomitant coronary artery disease. Conclusions Patients with familial DCM and Purkinje-related ventricular arrhythmias should be offered genetic screening. The quinidine treatment for the SCN5A R222Q mutation can be life saving for patients.
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Affiliation(s)
| | - Maria Franaszczyk
- Molecular Biology Laboratory, Department of Medical Biology, Institute of Cardiology, ul. Alpejska 42, 04-628, Warszawa, Poland
| | - Zofia Bilińska
- Unit for Screening Studies in Inherited Cardiovascular Diseases, Institute of Cardiology, ul. Alpejska 42, 04-628, Warszawa, Poland.
| | - Grażyna Truszkowska
- Molecular Biology Laboratory, Department of Medical Biology, Institute of Cardiology, ul. Alpejska 42, 04-628, Warszawa, Poland
| | - Małgorzata Karczmarz
- Department of Heart Failure and Transplantology, Institute of Cardiology, ul. Alpejska 42, 04-628, Warszawa, Poland
| | - Łukasz Szumowski
- Department of Arrhythmia, Institute of Cardiology, ul. Alpejska 42, 04-628, Warszawa, Poland
| | - Tomasz Zieliński
- Department of Heart Failure and Transplantology, Institute of Cardiology, ul. Alpejska 42, 04-628, Warszawa, Poland
| | - Rafał Płoski
- Department of Medical Genetics, Medical University of Warsaw, ul. Pawinskiego 3c, 02-106, Warszawa, Poland.
| | - Maria Bilińska
- Department of Arrhythmia, Institute of Cardiology, ul. Alpejska 42, 04-628, Warszawa, Poland
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26
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Wilde AAM, Amin AS. Clinical Spectrum of SCN5A Mutations: Long QT Syndrome, Brugada Syndrome, and Cardiomyopathy. JACC Clin Electrophysiol 2018; 4:569-579. [PMID: 29798782 DOI: 10.1016/j.jacep.2018.03.006] [Citation(s) in RCA: 190] [Impact Index Per Article: 31.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Revised: 03/02/2018] [Accepted: 03/08/2018] [Indexed: 12/13/2022]
Abstract
SCN5A gene encodes the pore-forming ion-conducting α-subunit of the cardiac sodium channel (Nav1.5), which is responsible for the initiation and propagation of action potentials and thereby determines cardiac excitability and conduction of electrical stimuli through the heart. The importance of Nav1.5 for normal cardiac electricity is reflected by various disease entities that can be caused by mutations in SCN5A. Gain-of-function mutations in SCN5A lead to more sodium influx into cardiomyocytes through aberrant channel gating and cause long QT syndrome, a primary electrical disease of the heart. Loss-of-function mutations in SCN5A lead to lower expression levels of SCN5A or production of defective Nav1.5 proteins and cause Brugada syndrome, an electrical disease with minor structural changes in the heart. In addition, both loss- and gain-of-function mutations may cause dilated cardiomyopathy, which is an arrhythmogenic disease with gross structural defects of the left ventricle (and sometimes both ventricles). Other SCN5A-related diseases are multifocal ectopic premature Purkinje-related complexes (gain-of-function mutations), isolated cardiac conduction defect (loss-of-function mutations), sick sinus syndrome (loss-of-function mutations), atrial fibrillation (loss-of-function or gain-of-function mutations), and overlap syndromes (mutations with both loss-of-function and gain-of-function effects). Growing insights into the role of SCN5A in health and disease has enabled clinicians to lay out gene-specific risk stratification schemes and mutation-specific diagnostic and therapeutic strategies in the management of patients with a SCN5A mutation. This review summarizes currently available knowledge about the pathophysiological mechanisms of SCN5A mutations and describes how this knowledge can be used to manage patients suffering from potentially lethal cardiac diseases.
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Affiliation(s)
- Arthur A M Wilde
- Heart Centre Academic Medical Center, Department of Clinical and Experimental Cardiology, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands; Princess Al-Jawhara Al-Brahim Centre of Excellence in Research of Hereditary Disorders, Jeddah, Kingdom of Saudi Arabia; Department of Medicine, Columbia University Irving Medical Centre, New York, New York.
| | - Ahmad S Amin
- Heart Centre Academic Medical Center, Department of Clinical and Experimental Cardiology, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands
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Multifocal atrial and ventricular premature contractions with an increased risk of dilated cardiomyopathy caused by a Na v 1.5 gain-of-function mutation (G213D). Int J Cardiol 2018; 257:160-167. [DOI: 10.1016/j.ijcard.2017.11.095] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/24/2017] [Revised: 10/24/2017] [Accepted: 11/27/2017] [Indexed: 01/14/2023]
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28
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Abstract
Voltage-gated sodium channels belong to the superfamily of voltage-gated cation channels. Their structure is based on domains comprising a voltage sensor domain (S1-S4 segments) and a pore domain (S5-S6 segments). Mutations in positively charged residues of the S4 segments may allow protons or cations to pass directly through the gating pore constriction of the voltage sensor domain; these anomalous currents are referred to as gating pore or omega (ω) currents. In the skeletal muscle disorder hypokalemic periodic paralysis, and in arrhythmic dilated cardiomyopathy, inherited mutations of S4 arginine residues promote omega currents that have been shown to be a contributing factor in the pathogenesis of these sodium channel disorders. Characterization of gating pore currents in these channelopathies and with artificial mutations has been possible by measuring the voltage-dependence and selectivity of these leak currents. The basis of gating pore currents and the structural basis of S4 movement through the gating pore has also been studied extensively with molecular dynamics. These simulations have provided valuable insight into the nature of S4 translocation and the physical basis for the effects of mutations that promote permeation of protons or cations through the gating pore.
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Affiliation(s)
- J R Groome
- Department of Biological Sciences, Idaho State University, Pocatello, ID, 83209, USA.
| | - A Moreau
- Institut NeuroMyogene, ENS de Lyon, Site MONOD, Lyon, France
| | - L Delemotte
- Science for Life Laboratory, Department of Physics, KTH Royal Institute of Technology, Box 1031, 171 21, Solna, Sweden
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29
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Savio-Galimberti E, Argenziano M, Antzelevitch C. Cardiac Arrhythmias Related to Sodium Channel Dysfunction. Handb Exp Pharmacol 2018; 246:331-354. [PMID: 28965168 DOI: 10.1007/164_2017_43] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The voltage-gated cardiac sodium channel (Nav1.5) is a mega-complex comprised of a pore-forming α subunit and 4 ancillary β-subunits together with numerous protein partners. Genetic defects in the form of rare variants in one or more sodium channel-related genes can cause a loss- or gain-of-function of sodium channel current (INa) leading to the manifestation of various disease phenotypes, including Brugada syndrome, long QT syndrome, progressive cardiac conduction disease, sick sinus syndrome, multifocal ectopic Purkinje-related premature contractions, and atrial fibrillation. Some sodium channelopathies have also been shown to be responsible for sudden infant death syndrome (SIDS). Although these genetic defects often present as pure electrical diseases, recent studies point to a contribution of structural abnormalities to the electrocardiographic and arrhythmic manifestation in some cases, such as dilated cardiomyopathy. The same rare variants in SCN5A or related genes may present with different clinical phenotypes in different individuals and sometimes in members of the same family. Genetic background and epigenetic and environmental factors contribute to the expression of these overlap syndromes. Our goal in this chapter is to review and discuss what is known about the clinical phenotype and genotype of each cardiac sodium channelopathy, and to briefly discuss the underlying mechanisms.
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Affiliation(s)
| | - Mariana Argenziano
- Lankenau Institute for Medical Research, 100 E. Lancaster Avenue, Wynnewood, PA, 19096, USA
| | - Charles Antzelevitch
- Lankenau Institute for Medical Research, 100 E. Lancaster Avenue, Wynnewood, PA, 19096, USA.
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30
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Abstract
Nonischemic dilated cardiomyopathy (DCM) often has a genetic pathogenesis. Because of the large number of genes and alleles attributed to DCM, comprehensive genetic testing encompasses ever-increasing gene panels. Genetic diagnosis can help predict prognosis, especially with regard to arrhythmia risk for certain subtypes. Moreover, cascade genetic testing in family members can identify those who are at risk or with early stage disease, offering the opportunity for early intervention. This review will address diagnosis and management of DCM, including the role of genetic evaluation. We will also overview distinct genetic pathways linked to DCM and their pathogenetic mechanisms. Historically, cardiac morphology has been used to classify cardiomyopathy subtypes. Determining genetic variants is emerging as an additional adjunct to help further refine subtypes of DCM, especially where arrhythmia risk is increased, and ultimately contribute to clinical management.
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Affiliation(s)
- Elizabeth M McNally
- From the Center for Genetic Medicine, Northwestern University Feinberg School of Medicine, Chicago IL (E.M.M.); and Cardiovascular Institute, University of Colorado Anschutz Medical Campus, Aurora (L.M.).
| | - Luisa Mestroni
- From the Center for Genetic Medicine, Northwestern University Feinberg School of Medicine, Chicago IL (E.M.M.); and Cardiovascular Institute, University of Colorado Anschutz Medical Campus, Aurora (L.M.).
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31
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Roston TM, Cunningham T, Lehman A, Laksman ZW, Krahn AD, Sanatani S. Beyond the Electrocardiogram: Mutations in Cardiac Ion Channel Genes Underlie Nonarrhythmic Phenotypes. CLINICAL MEDICINE INSIGHTS-CARDIOLOGY 2017; 11:1179546817698134. [PMID: 28469493 PMCID: PMC5392026 DOI: 10.1177/1179546817698134] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Accepted: 02/01/2017] [Indexed: 12/19/2022]
Abstract
Cardiac ion channelopathies are an important cause of sudden death in the young and include long QT syndrome, Brugada syndrome, catecholaminergic polymorphic ventricular tachycardia, idiopathic ventricular fibrillation, and short QT syndrome. Genes that encode ion channels have been implicated in all of these conditions, leading to the widespread implementation of genetic testing for suspected channelopathies. Over the past half-century, researchers have also identified systemic pathologies that extend beyond the arrhythmic phenotype in patients with ion channel gene mutations, including deafness, epilepsy, cardiomyopathy, periodic paralysis, and congenital heart disease. A coexisting phenotype, such as cardiomyopathy, can influence evaluation and management. However, prior to recent molecular advances, our understanding and recognition of these overlapping phenotypes were poor. This review highlights the systemic and structural heart manifestations of the cardiac ion channelopathies, including their phenotypic spectrum and molecular basis.
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Affiliation(s)
- Thomas M Roston
- British Columbia Inherited Arrhythmia Program and University of British Columbia, Vancouver, BC, Canada
| | - Taylor Cunningham
- British Columbia Inherited Arrhythmia Program and University of British Columbia, Vancouver, BC, Canada
| | - Anna Lehman
- British Columbia Inherited Arrhythmia Program and University of British Columbia, Vancouver, BC, Canada
| | - Zachary W Laksman
- British Columbia Inherited Arrhythmia Program and University of British Columbia, Vancouver, BC, Canada
| | - Andrew D Krahn
- British Columbia Inherited Arrhythmia Program and University of British Columbia, Vancouver, BC, Canada
| | - Shubhayan Sanatani
- British Columbia Inherited Arrhythmia Program and University of British Columbia, Vancouver, BC, Canada.,Children's Heart Centre, BC Children's Hospital, Vancouver, BC, Canada
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32
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Loussouarn G, Sternberg D, Nicole S, Marionneau C, Le Bouffant F, Toumaniantz G, Barc J, Malak OA, Fressart V, Péréon Y, Baró I, Charpentier F. Physiological and Pathophysiological Insights of Nav1.4 and Nav1.5 Comparison. Front Pharmacol 2016; 6:314. [PMID: 26834636 PMCID: PMC4712308 DOI: 10.3389/fphar.2015.00314] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Accepted: 12/21/2015] [Indexed: 12/19/2022] Open
Abstract
Mutations in Nav1.4 and Nav1.5 α-subunits have been associated with muscular and cardiac channelopathies, respectively. Despite intense research on the structure and function of these channels, a lot of information is still missing to delineate the various physiological and pathophysiological processes underlying their activity at the molecular level. Nav1.4 and Nav1.5 sequences are similar, suggesting structural and functional homologies between the two orthologous channels. This also suggests that any characteristics described for one channel subunit may shed light on the properties of the counterpart channel subunit. In this review article, after a brief clinical description of the muscular and cardiac channelopathies related to Nav1.4 and Nav1.5 mutations, respectively, we compare the knowledge accumulated in different aspects of the expression and function of Nav1.4 and Nav1.5 α-subunits: the regulation of the two encoding genes (SCN4A and SCN5A), the associated/regulatory proteins and at last, the functional effect of the same missense mutations detected in Nav1.4 and Nav1.5. First, it appears that more is known on Nav1.5 expression and accessory proteins. Because of the high homologies of Nav1.5 binding sites and equivalent Nav1.4 sites, Nav1.5-related results may guide future investigations on Nav1.4. Second, the analysis of the same missense mutations in Nav1.4 and Nav1.5 revealed intriguing similarities regarding their effects on membrane excitability and alteration in channel biophysics. We believe that such comparison may bring new cues to the physiopathology of cardiac and muscular diseases.
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Affiliation(s)
- Gildas Loussouarn
- Institut National de la Santé et de la Recherche Médicale, UMR 1087, l'Institut du ThoraxNantes, France; Centre National de la Recherche Scientifique, UMR 6291Nantes, France; Université de NantesNantes, France
| | - Damien Sternberg
- Institut National de la Santé et de la Recherche Médicale, U1127Paris, France; Sorbonne Universités, Université Pierre-et-Marie-Curie, UMR S1127Paris, France; Centre National de la Recherche Scientifique, UMR 7225Paris, France; Institut du Cerveau et de la Moelle Épinière, ICMParis, France; Assistance Publique - Hôpitaux de Paris (AP-HP), Centres de Référence des Canalopathies Musculaires et des Maladies Neuro-musculaires Paris-EstParis, France; Assistance Publique - Hôpitaux de Paris (AP-HP), Hôpital de la Pitié Salpêtrière, Service de Biochimie Métabolique, Unité de Cardiogénétique et MyogénétiqueParis, France
| | - Sophie Nicole
- Institut National de la Santé et de la Recherche Médicale, U1127Paris, France; Sorbonne Universités, Université Pierre-et-Marie-Curie, UMR S1127Paris, France; Centre National de la Recherche Scientifique, UMR 7225Paris, France; Institut du Cerveau et de la Moelle Épinière, ICMParis, France
| | - Céline Marionneau
- Institut National de la Santé et de la Recherche Médicale, UMR 1087, l'Institut du ThoraxNantes, France; Centre National de la Recherche Scientifique, UMR 6291Nantes, France; Université de NantesNantes, France
| | - Francoise Le Bouffant
- Institut National de la Santé et de la Recherche Médicale, UMR 1087, l'Institut du ThoraxNantes, France; Centre National de la Recherche Scientifique, UMR 6291Nantes, France; Université de NantesNantes, France
| | - Gilles Toumaniantz
- Institut National de la Santé et de la Recherche Médicale, UMR 1087, l'Institut du ThoraxNantes, France; Centre National de la Recherche Scientifique, UMR 6291Nantes, France; Université de NantesNantes, France
| | - Julien Barc
- Institut National de la Santé et de la Recherche Médicale, UMR 1087, l'Institut du ThoraxNantes, France; Centre National de la Recherche Scientifique, UMR 6291Nantes, France; Université de NantesNantes, France
| | - Olfat A Malak
- Institut National de la Santé et de la Recherche Médicale, UMR 1087, l'Institut du ThoraxNantes, France; Centre National de la Recherche Scientifique, UMR 6291Nantes, France; Université de NantesNantes, France
| | - Véronique Fressart
- Assistance Publique - Hôpitaux de Paris (AP-HP), Hôpital de la Pitié Salpêtrière, Service de Biochimie Métabolique, Unité de Cardiogénétique et Myogénétique Paris, France
| | - Yann Péréon
- Centre Hospitalier Universitaire de Nantes, Centre de Référence Maladies Neuromusculaires Nantes-AngersNantes, France; Atlantic Gene Therapies - Biotherapy Institute for Rare DiseasesNantes, France
| | - Isabelle Baró
- Institut National de la Santé et de la Recherche Médicale, UMR 1087, l'Institut du ThoraxNantes, France; Centre National de la Recherche Scientifique, UMR 6291Nantes, France; Université de NantesNantes, France
| | - Flavien Charpentier
- Institut National de la Santé et de la Recherche Médicale, UMR 1087, l'Institut du ThoraxNantes, France; Centre National de la Recherche Scientifique, UMR 6291Nantes, France; Université de NantesNantes, France; Centre Hospitalier Universitaire de Nantes, l'Institut du ThoraxNantes, France
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33
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Moreau A, Gosselin-Badaroudine P, Boutjdir M, Chahine M. Mutations in the Voltage Sensors of Domains I and II of Nav1.5 that are Associated with Arrhythmias and Dilated Cardiomyopathy Generate Gating Pore Currents. Front Pharmacol 2015; 6:301. [PMID: 26733869 PMCID: PMC4689871 DOI: 10.3389/fphar.2015.00301] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2015] [Accepted: 12/09/2015] [Indexed: 12/19/2022] Open
Abstract
Voltage gated sodium channels (Nav) are transmembrane proteins responsible for action potential initiation. Mutations mainly located in the voltage sensor domain (VSD) of Nav1.5, the cardiac sodium channel, have been associated with the development of arrhythmias combined with dilated cardiomyopathy. Gating pore currents have been observed with three unrelated mutations associated with similar clinical phenotypes. However, gating pores have never been associated with mutations outside the first domain of Nav1.5. The aim of this study was to explore the possibility that gating pore currents might be caused by the Nav1.5 R225P and R814W mutations (R3, S4 in DI and DII, respectively), which are associated with rhythm disturbances and dilated cardiomyopathy. Nav1.5 WT and mutant channels were transiently expressed in tsA201 cells. The biophysical properties of the alpha pore currents and the presence of gating pore currents were investigated using the patch-clamp technique. We confirmed the previously reported gain of function of the alpha pores of the mutant channels, which mainly consisted of increased window currents mostly caused by shifts in the voltage dependence of activation. We also observed gating pore currents associated with the R225P and R814W mutations. This novel permeation pathway was open under depolarized conditions and remained temporarily open at hyperpolarized potentials after depolarization periods. Gating pore currents could represent a molecular basis for the development of uncommon electrical abnormalities and changes in cardiac morphology. We propose that this biophysical defect be routinely evaluated in the case of Nav1.5 mutations on the VSD.
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Affiliation(s)
- Adrien Moreau
- Centre de Recherche de l'Institut Universitaire en Santé Mentale de Québec, Quebec City QC, Canada
| | | | - Mohamed Boutjdir
- Cardiovascular Research Program, VA New York Harbor Healthcare System, Brooklyn NY, USA
| | - Mohamed Chahine
- Centre de Recherche de l'Institut Universitaire en Santé Mentale de Québec, Quebec CityQC, Canada; Department of Medicine, Université Laval, Quebec CityQC, Canada
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Moreau A, Gosselin-Badaroudine P, Delemotte L, Klein ML, Chahine M. Gating pore currents are defects in common with two Nav1.5 mutations in patients with mixed arrhythmias and dilated cardiomyopathy. ACTA ACUST UNITED AC 2015; 145:93-106. [PMID: 25624448 PMCID: PMC4306709 DOI: 10.1085/jgp.201411304] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Nav1.5 channels bearing voltage-sensor domain mutations associated with atypical cardiac arrhythmias and dilated cardiomyopathy generate gating pore currents. The gating pore current, also called omega current, consists of a cation leak through the typically nonconductive voltage-sensor domain (VSD) of voltage-gated ion channels. Although the study of gating pore currents has refined our knowledge of the structure and the function of voltage-gated ion channels, their implication in cardiac disorders has not been established. Two Nav1.5 mutations (R222Q and R225W) located in the VSD are associated with atypical clinical phenotypes involving complex arrhythmias and dilated cardiomyopathy. Using the patch-clamp technique, in silico mutagenesis, and molecular dynamic simulations, we tested the hypothesis that these two mutations may generate gating pore currents, potentially accounting for their clinical phenotypes. Our findings suggest that the gating pore current generated by the R222Q and R225W mutations could constitute the underlying pathological mechanism that links Nav1.5 VSD mutations with human cardiac arrhythmias and dilatation of cardiac chambers.
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Affiliation(s)
- Adrien Moreau
- Centre de Recherche de L'Institut Universitaire en Santé Mentale de Québec, Québec City, Québec G1J 2G3, Canada
| | - Pascal Gosselin-Badaroudine
- Centre de Recherche de L'Institut Universitaire en Santé Mentale de Québec, Québec City, Québec G1J 2G3, Canada
| | - Lucie Delemotte
- Institute of Computational Molecular Science, Temple University, Philadelphia, PA 19122
| | - Michael L Klein
- Institute of Computational Molecular Science, Temple University, Philadelphia, PA 19122
| | - Mohamed Chahine
- Centre de Recherche de L'Institut Universitaire en Santé Mentale de Québec, Québec City, Québec G1J 2G3, Canada Department of Medicine, Université Laval, Québec City, Québec G1K 7P4, Canada
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35
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Amarouch MY, Swan H, Leinonen J, Marjamaa A, Lahtinen AM, Kontula K, Toivonen L, Widen E, Abriel H. Antiarrhythmic Action of Flecainide in Polymorphic Ventricular Arrhythmias Caused by a Gain-of-Function Mutation in the Nav 1.5 Sodium Channel. Ann Noninvasive Electrocardiol 2015; 21:343-51. [PMID: 26965448 DOI: 10.1111/anec.12312] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Revised: 07/04/2015] [Accepted: 07/15/2015] [Indexed: 01/02/2023] Open
Abstract
BACKGROUND The cardiac sodium channel Nav 1.5, encoded by the gene SCN5A, is associated with a wide spectrum of hereditary arrhythmias. The gain-of-function mutation p.I141V in SCN5A was identified in a large multigenerational family with exercise-induced polymorphic ventricular arrhythmias. The purpose of this study was to evaluate the molecular and clinical effects of flecainide administration on patients with this syndrome. METHODS Eleven p.I141V carriers who exhibited frequent multiformic premature ventricular complexes (PVCs) during exercise were subjected to exercise stress tests, both before and after intravenous infusion of 2 mg/kg flecainide. The in vitro effects of flecainide were evaluated using the patch-clamp technique with HEK293 cells expressing the Nav 1.5 channel. RESULTS The flecainide treatment significantly reduced the frequency of PVCs during and after exercise. Next, the sensitivity of the p.I141V mutant channel to flecainide was compared to that of the wild type channel. Perfusion of flecainide inhibited the peak and window currents in both groups. CONCLUSION The clinical investigations of the affected patients, as well as the molecular and pharmacological characterization of the SCN5A p.I141V mutation, provide new evidence supporting the association of this mutation with exercise-induced polymorphic ventricular arrhythmias. These data also demonstrate that flecainide may serve as an effective treatment for the defect in Nav 1.5 that leads to an increased sodium window current.
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Affiliation(s)
| | - Heikki Swan
- Heart and Lung Center, Helsinki University Central Hospital, Helsinki, Finland
| | - Jaakko Leinonen
- Institute for Molecular Medicine Finland (FIMM), University of Helsinki, Helsinki, Finland
| | - Annukka Marjamaa
- Heart and Lung Center, Helsinki University Central Hospital, Helsinki, Finland
| | - Annukka M Lahtinen
- Department of Medicine, University of Helsinki and Helsinki University Central Hospital, Helsinki, Finland
| | - Kimmo Kontula
- Department of Medicine, University of Helsinki and Helsinki University Central Hospital, Helsinki, Finland
| | - Lauri Toivonen
- Heart and Lung Center, Helsinki University Central Hospital, Helsinki, Finland
| | - Elisabeth Widen
- Institute for Molecular Medicine Finland (FIMM), University of Helsinki, Helsinki, Finland
| | - Hugues Abriel
- Department of Clinical Research, University of Bern, Bern, Switzerland
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Veerman CC, Wilde AAM, Lodder EM. The cardiac sodium channel gene SCN5A and its gene product NaV1.5: Role in physiology and pathophysiology. Gene 2015; 573:177-87. [PMID: 26361848 DOI: 10.1016/j.gene.2015.08.062] [Citation(s) in RCA: 111] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2015] [Revised: 07/31/2015] [Accepted: 08/27/2015] [Indexed: 12/18/2022]
Abstract
The gene SCN5A encodes the main cardiac sodium channel NaV1.5. This channel predominates the cardiac sodium current, INa, which underlies the fast upstroke of the cardiac action potential. As such, it plays a crucial role in cardiac electrophysiology. Over the last 60years a tremendous amount of knowledge regarding its function at the electrophysiological and molecular level has been acquired. Furthermore, genetic studies have shown that mutations in SCN5A are associated with multiple cardiac diseases (e.g. Brugada syndrome, Long QT syndrome, conduction disease and cardiomyopathy), while genetic variation in the general population has been associated with differences in cardiac conduction and risk of arrhythmia through genome wide association studies. In this review we aim to give an overview of the current knowledge (and the gaps therein) on SCN5A and NaV1.5.
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Affiliation(s)
- Christiaan C Veerman
- Department of Clinical and Experimental Cardiology, Academic Medical Center, Amsterdam, The Netherlands
| | - Arthur A M Wilde
- Department of Clinical and Experimental Cardiology, Academic Medical Center, Amsterdam, The Netherlands.
| | - Elisabeth M Lodder
- Department of Clinical and Experimental Cardiology, Academic Medical Center, Amsterdam, The Netherlands.
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Nakajima T, Kaneko Y, Saito A, Ota M, Iijima T, Kurabayashi M. Enhanced fast-inactivated state stability of cardiac sodium channels by a novel voltage sensor SCN5A mutation, R1632C, as a cause of atypical Brugada syndrome. Heart Rhythm 2015; 12:2296-304. [PMID: 26031372 DOI: 10.1016/j.hrthm.2015.05.032] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/10/2015] [Indexed: 12/19/2022]
Abstract
BACKGROUND Mutations in SCN5A, which encodes the cardiac voltage-gated sodium channels, can be associated with multiple electrophysiological phenotypes. A novel SCN5A R1632C mutation, located in the domain IV-segment 4 voltage sensor, was identified in a young male patient who had a syncopal episode during exercise and presented with atrial tachycardia, sinus node dysfunction, and Brugada syndrome. OBJECTIVE We sought to elucidate the functional consequences of the R1632C mutation. METHODS The wild-type (WT) or R1632C SCN5A mutation was coexpressed with β1 subunit in tsA201 cells, and whole-cell sodium currents (INa) were recorded using patch-clamp methods. RESULTS INa density, measured at -20 mV from a holding potential of -120 mV, for R1632C was significantly lower than that for WT (R1632C: -433 ± 52 pA/pF, n = 14; WT: -672 ± 90 pA/pF, n = 15; P < .05); however, no significant changes were observed in the steady-state activation and fast inactivation rate. The steady-state inactivation curve for R1632C was remarkably shifted to hyperpolarizing potentials compared with that for WT (R1632C: V1/2 = -110.7 ± 0.8 mV, n = 16; WT: V1/2 = -85.9 ± 2.5 mV, n = 17; P < .01). The steady-state fast inactivation curve for R1632C was also shifted to the same degree. Recovery from fast inactivation after a 20-ms depolarizing pulse for R1632C was remarkably delayed compared with that for WT (R1632C: τ = 246.7 ± 14.3 ms, n = 8; WT: τ = 3.7 ± 0.3 ms, n = 8; P < .01). Repetitive depolarizing pulses at various cycle lengths greatly attenuated INa for R1632C than that for WT. CONCLUSION R1632C showed a loss of function of INa by an enhanced fast-inactivated state stability because of a pronounced impairment of recovery from fast inactivation, which may explain the phenotypic manifestation observed in our patient.
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Affiliation(s)
- Tadashi Nakajima
- Department of Medicine and Biological Science, Gunma University Graduate School of Medicine, Maebashi, Japan.
| | - Yoshiaki Kaneko
- Department of Medicine and Biological Science, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Akihiro Saito
- Department of Medicine and Biological Science, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Masaki Ota
- Department of Medicine and Biological Science, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Takafumi Iijima
- Department of Medicine and Biological Science, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Masahiko Kurabayashi
- Department of Medicine and Biological Science, Gunma University Graduate School of Medicine, Maebashi, Japan
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Abstract
Inherited arrhythmia syndromes are collectively associated with substantial morbidity, yet our understanding of the genetic architecture of these conditions remains limited. Recent technological advances in DNA sequencing have led to the commercialization of genetic testing now widely available in clinical practice. In particular, next-generation sequencing allows the large-scale and rapid assessment of entire genomes. Although next-generation sequencing represents a major technological advance, it has introduced numerous challenges with respect to the interpretation of genetic variation and has opened a veritable floodgate of biological data of unknown clinical significance to practitioners. In this review, we discuss current genetic testing indications for inherited arrhythmia syndromes, broadly outline characteristics of next-generation sequencing techniques, and highlight challenges associated with such testing. We further summarize future directions that will be necessary to address to enable the widespread adoption of next-generation sequencing in the routine management of patients with inherited arrhythmia syndromes.
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Affiliation(s)
- Steven A Lubitz
- Cardiac Arrhythmia Service and Cardiovascular Research Center, Massachusetts General Hospital, Boston, Massachusetts, and Medical and Population Genetics Program, The Broad Institute, Cambridge, Massachusetts.
| | - Patrick T Ellinor
- Cardiac Arrhythmia Service and Cardiovascular Research Center, Massachusetts General Hospital, Boston, Massachusetts, and Medical and Population Genetics Program, The Broad Institute, Cambridge, Massachusetts
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39
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Amarouch MY, Abriel H. Cellular hyper-excitability caused by mutations that alter the activation process of voltage-gated sodium channels. Front Physiol 2015; 6:45. [PMID: 25741286 PMCID: PMC4330716 DOI: 10.3389/fphys.2015.00045] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Accepted: 01/30/2015] [Indexed: 12/19/2022] Open
Abstract
Voltage-gated sodium channels (Nav) are widely expressed as macro-molecular complexes in both excitable and non-excitable tissues. In excitable tissues, the upstroke of the action potential is the result of the passage of a large and rapid influx of sodium ions through these channels. NaV dysfunction has been associated with an increasingly wide range of neurological, muscular and cardiac disorders. The purpose of this review is to summarize the recently identified sodium channel mutations that are linked to hyper-excitability phenotypes and associated with the alteration of the activation process of voltage gated sodium channels. Indeed, several clinical manifestations that demonstrate an alteration of tissue excitability were recently shown to be strongly associated with the presence of mutations that affect the activation process of the Nav. These emerging genotype-phenotype correlations have expanded the clinical spectrum of sodium channelopathies to include disorders which feature a hyper-excitability phenotype that may or may not be associated with a cardiomyopathy. The p.I141V mutation in SCN4A and SCN5A, as well as its homologous p.I136V mutation in SCN9A, are interesting examples of mutations that have been linked to inherited hyperexcitability myotonia, exercise-induced polymorphic ventricular arrhythmias and erythromelalgia, respectively. Regardless of which sodium channel isoform is investigated, the substitution of the isoleucine to valine in the locus 141 induces similar modifications in the biophysical properties of the Nav by shifting the voltage-dependence of steady state activation toward more negative potentials.
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Affiliation(s)
- Mohamed-Yassine Amarouch
- Materials, Natural Substances, Environment and Modeling Laboratory, Multidisciplinary Faculty of Taza, University of Sidi Mohamed Ben Abdellah-Fes Taza, Morocco
| | - Hugues Abriel
- Department of Clinical Research, University of Bern Bern, Switzerland
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Swan H, Amarouch MY, Leinonen J, Marjamaa A, Kucera JP, Laitinen-Forsblom PJ, Lahtinen AM, Palotie A, Kontula K, Toivonen L, Abriel H, Widen E. Gain-of-Function Mutation of the
SCN5A
Gene Causes Exercise-Induced Polymorphic Ventricular Arrhythmias. ACTA ACUST UNITED AC 2014; 7:771-81. [DOI: 10.1161/circgenetics.114.000703] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Background—
Over the past 15 years, a myriad of mutations in genes encoding cardiac ion channels and ion channel interacting proteins have been linked to a long list of inherited atrial and ventricular arrhythmias. The purpose of this study was to identify the genetic and functional determinants underlying exercise-induced polymorphic ventricular arrhythmia present in a large multigenerational family.
Methods and Results—
A large 4-generation family presenting with exercise-induced polymorphic ventricular arrhythmia, which was followed for 10 years, was clinically characterized. A novel
SCN5A
mutation was identified via whole exome sequencing and further functionally evaluated by patch-clamp studies using human embryonic kidney 293 cells. Of 37 living family members, a total of 13 individuals demonstrated ≥50 multiformic premature ventricular complexes or ventricular tachycardia upon exercise stress tests when sinus rate exceeded 99±17 beats per minute. Sudden cardiac arrest occurred in 1 individual during follow-up. Exome sequencing identified a novel missense mutation (p.I141V) in a highly conserved region of the
SCN5A
gene, encoding the Na
v
1.5 sodium channel protein that cosegregated with the arrhythmia phenotype. The mutation p.I141V shifted the activation curve toward more negative potentials and increased the window current, whereas action potential simulations suggested that it lowered the excitability threshold of cardiac cells.
Conclusions—
Gain-of-function of Na
v
1.5 may cause familial forms of exercise-induced polymorphic ventricular arrhythmias.
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Affiliation(s)
- Heikki Swan
- From the Heart and Lung Center, Helsinki University Central Hospital, Helsinki, Finland (H.S., A.M., L.T.); Department of Clinical Research (M.Y.A., H.A), and Department of Physiology (J.P.K), University of Bern, Bern, Switzerland. and Institute for Molecular Medicine Finland (FIMM), University of Helsinki (J.L., A.P., E.W.), and Department of Medicine, University of Helsinki and Helsinki University Central Hospital (P.J.L.-F., A.M.L., K.K.), Helsinki, Finland
| | - Mohamed Yassine Amarouch
- From the Heart and Lung Center, Helsinki University Central Hospital, Helsinki, Finland (H.S., A.M., L.T.); Department of Clinical Research (M.Y.A., H.A), and Department of Physiology (J.P.K), University of Bern, Bern, Switzerland. and Institute for Molecular Medicine Finland (FIMM), University of Helsinki (J.L., A.P., E.W.), and Department of Medicine, University of Helsinki and Helsinki University Central Hospital (P.J.L.-F., A.M.L., K.K.), Helsinki, Finland
| | - Jaakko Leinonen
- From the Heart and Lung Center, Helsinki University Central Hospital, Helsinki, Finland (H.S., A.M., L.T.); Department of Clinical Research (M.Y.A., H.A), and Department of Physiology (J.P.K), University of Bern, Bern, Switzerland. and Institute for Molecular Medicine Finland (FIMM), University of Helsinki (J.L., A.P., E.W.), and Department of Medicine, University of Helsinki and Helsinki University Central Hospital (P.J.L.-F., A.M.L., K.K.), Helsinki, Finland
| | - Annukka Marjamaa
- From the Heart and Lung Center, Helsinki University Central Hospital, Helsinki, Finland (H.S., A.M., L.T.); Department of Clinical Research (M.Y.A., H.A), and Department of Physiology (J.P.K), University of Bern, Bern, Switzerland. and Institute for Molecular Medicine Finland (FIMM), University of Helsinki (J.L., A.P., E.W.), and Department of Medicine, University of Helsinki and Helsinki University Central Hospital (P.J.L.-F., A.M.L., K.K.), Helsinki, Finland
| | - Jan P. Kucera
- From the Heart and Lung Center, Helsinki University Central Hospital, Helsinki, Finland (H.S., A.M., L.T.); Department of Clinical Research (M.Y.A., H.A), and Department of Physiology (J.P.K), University of Bern, Bern, Switzerland. and Institute for Molecular Medicine Finland (FIMM), University of Helsinki (J.L., A.P., E.W.), and Department of Medicine, University of Helsinki and Helsinki University Central Hospital (P.J.L.-F., A.M.L., K.K.), Helsinki, Finland
| | - Päivi J. Laitinen-Forsblom
- From the Heart and Lung Center, Helsinki University Central Hospital, Helsinki, Finland (H.S., A.M., L.T.); Department of Clinical Research (M.Y.A., H.A), and Department of Physiology (J.P.K), University of Bern, Bern, Switzerland. and Institute for Molecular Medicine Finland (FIMM), University of Helsinki (J.L., A.P., E.W.), and Department of Medicine, University of Helsinki and Helsinki University Central Hospital (P.J.L.-F., A.M.L., K.K.), Helsinki, Finland
| | - Annukka M. Lahtinen
- From the Heart and Lung Center, Helsinki University Central Hospital, Helsinki, Finland (H.S., A.M., L.T.); Department of Clinical Research (M.Y.A., H.A), and Department of Physiology (J.P.K), University of Bern, Bern, Switzerland. and Institute for Molecular Medicine Finland (FIMM), University of Helsinki (J.L., A.P., E.W.), and Department of Medicine, University of Helsinki and Helsinki University Central Hospital (P.J.L.-F., A.M.L., K.K.), Helsinki, Finland
| | - Aarno Palotie
- From the Heart and Lung Center, Helsinki University Central Hospital, Helsinki, Finland (H.S., A.M., L.T.); Department of Clinical Research (M.Y.A., H.A), and Department of Physiology (J.P.K), University of Bern, Bern, Switzerland. and Institute for Molecular Medicine Finland (FIMM), University of Helsinki (J.L., A.P., E.W.), and Department of Medicine, University of Helsinki and Helsinki University Central Hospital (P.J.L.-F., A.M.L., K.K.), Helsinki, Finland
| | - Kimmo Kontula
- From the Heart and Lung Center, Helsinki University Central Hospital, Helsinki, Finland (H.S., A.M., L.T.); Department of Clinical Research (M.Y.A., H.A), and Department of Physiology (J.P.K), University of Bern, Bern, Switzerland. and Institute for Molecular Medicine Finland (FIMM), University of Helsinki (J.L., A.P., E.W.), and Department of Medicine, University of Helsinki and Helsinki University Central Hospital (P.J.L.-F., A.M.L., K.K.), Helsinki, Finland
| | - Lauri Toivonen
- From the Heart and Lung Center, Helsinki University Central Hospital, Helsinki, Finland (H.S., A.M., L.T.); Department of Clinical Research (M.Y.A., H.A), and Department of Physiology (J.P.K), University of Bern, Bern, Switzerland. and Institute for Molecular Medicine Finland (FIMM), University of Helsinki (J.L., A.P., E.W.), and Department of Medicine, University of Helsinki and Helsinki University Central Hospital (P.J.L.-F., A.M.L., K.K.), Helsinki, Finland
| | - Hugues Abriel
- From the Heart and Lung Center, Helsinki University Central Hospital, Helsinki, Finland (H.S., A.M., L.T.); Department of Clinical Research (M.Y.A., H.A), and Department of Physiology (J.P.K), University of Bern, Bern, Switzerland. and Institute for Molecular Medicine Finland (FIMM), University of Helsinki (J.L., A.P., E.W.), and Department of Medicine, University of Helsinki and Helsinki University Central Hospital (P.J.L.-F., A.M.L., K.K.), Helsinki, Finland
| | - Elisabeth Widen
- From the Heart and Lung Center, Helsinki University Central Hospital, Helsinki, Finland (H.S., A.M., L.T.); Department of Clinical Research (M.Y.A., H.A), and Department of Physiology (J.P.K), University of Bern, Bern, Switzerland. and Institute for Molecular Medicine Finland (FIMM), University of Helsinki (J.L., A.P., E.W.), and Department of Medicine, University of Helsinki and Helsinki University Central Hospital (P.J.L.-F., A.M.L., K.K.), Helsinki, Finland
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Beckermann TM, McLeod K, Murday V, Potet F, George AL. Novel SCN5A mutation in amiodarone-responsive multifocal ventricular ectopy-associated cardiomyopathy. Heart Rhythm 2014; 11:1446-53. [PMID: 24815523 DOI: 10.1016/j.hrthm.2014.04.042] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/31/2013] [Indexed: 12/19/2022]
Abstract
BACKGROUND Mutations in SCN5A, which encodes the cardiac sodium channel NaV1.5, typically cause ventricular arrhythmia or conduction slowing. Recently, SCN5A mutations have been associated with heart failure combined with variable atrial and ventricular arrhythmia. OBJECTIVE The purpose of this study was to determine the clinical, genetic, and functional features of an amiodarone-responsive multifocal ventricular ectopy-related cardiomyopathy associated with a novel mutation in a NaV1.5 voltage sensor domain. METHODS A novel, de novo SCN5A mutation (NaV1.5-R225P) was identified in a boy with prenatal arrhythmia and impaired cardiac contractility followed by postnatal multifocal ventricular ectopy suppressible by amiodarone. We investigated the functional consequences of NaV1.5-R225P expressed heterologously in tsA201 cells. RESULTS Mutant channels exhibited significant abnormalities in both activation and inactivation leading to large, hyperpolarized window and ramp currents that predict aberrant sodium influx at potentials near the cardiomyocyte resting membrane potential. Mutant channels also exhibited significantly increased persistent (late) sodium current. This profile of channel dysfunction shares features with other SCN5A voltage sensor mutations associated with cardiomyopathy and overlapped that of congenital long QT syndrome. Amiodarone stabilized fast inactivation, suppressed persistent sodium current, and caused frequency-dependent inhibition of channel availability. CONCLUSION We determined the functional consequences and pharmacologic responses of a novel SCN5A mutation associated with an arrhythmia-associated cardiomyopathy. Comparisons with other cardiomyopathy-associated NaV1.5 voltage sensor mutations revealed a pattern of abnormal voltage dependence of activation as a shared biophysical mechanism of the syndrome.
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Affiliation(s)
| | - Karen McLeod
- Royal Hospital for Sick Children, Yorkhill, Glasgow, Scotland, United Kingdom
| | - Victoria Murday
- Royal Hospital for Sick Children, Yorkhill, Glasgow, Scotland, United Kingdom
| | - Franck Potet
- Division of Genetic Medicine, Department of Medicine, Vanderbilt University, Nashville, Tennessee
| | - Alfred L George
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee; Division of Genetic Medicine, Department of Medicine, Vanderbilt University, Nashville, Tennessee.
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42
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Moreau A, Gosselin-Badaroudine P, Chahine M. Biophysics, pathophysiology, and pharmacology of ion channel gating pores. Front Pharmacol 2014; 5:53. [PMID: 24772081 PMCID: PMC3982104 DOI: 10.3389/fphar.2014.00053] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2014] [Accepted: 03/12/2014] [Indexed: 12/19/2022] Open
Abstract
Voltage sensor domains (VSDs) are a feature of voltage gated ion channels (VGICs) and voltage sensitive proteins. They are composed of four transmembrane (TM) segments (S1–S4). Currents leaking through VSDs are called omega or gating pore currents. Gating pores are caused by mutations of the highly conserved positively charged amino acids in the S4 segment that disrupt interactions between the S4 segment and the gating charge transfer center (GCTC). The GCTC separates the intracellular and extracellular water crevices. The disruption of S4–GCTC interactions allows these crevices to communicate and create a fast activating and non-inactivating alternative cation-selective permeation pathway of low conductance, or a gating pore. Gating pore currents have recently been shown to cause periodic paralysis phenotypes. There is also increasing evidence that gating pores are linked to several other familial diseases. For example, gating pores in Nav1.5 and Kv7.2 channels may underlie mixed arrhythmias associated with dilated cardiomyopathy (DCM) phenotypes and peripheral nerve hyperexcitability (PNH), respectively. There is little evidence for the existence of gating pore blockers. Moreover, it is known that a number of toxins bind to the VSD of a specific domain of Na+ channels. These toxins may thus modulate gating pore currents. This focus on the VSD motif opens up a new area of research centered on developing molecules to treat a number of cell excitability disorders such as epilepsy, cardiac arrhythmias, and pain. The purpose of the present review is to summarize existing knowledge of the pathophysiology, biophysics, and pharmacology of gating pore currents and to serve as a guide for future studies aimed at improving our understanding of gating pores and their pathophysiological roles.
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Affiliation(s)
- Adrien Moreau
- Centre de Recherche de L'Institut Universitaire en Santé Mentale de Québec Quebec City, QC, Canada
| | | | - Mohamed Chahine
- Centre de Recherche de L'Institut Universitaire en Santé Mentale de Québec Quebec City, QC, Canada ; Department of Medicine, Université Laval Quebec City, QC, Canada
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43
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Gosselin-Badaroudine P, Moreau A, Chahine M. Nav 1.5 mutations linked to dilated cardiomyopathy phenotypes: Is the gating pore current the missing link? Channels (Austin) 2013; 8:90-4. [PMID: 24300601 DOI: 10.4161/chan.27179] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Nav 1.5 dysfunctions are commonly linked to rhythms disturbances that include type 3 long QT syndrome (LQT3), Brugada syndrome (BrS), sick sinus syndrome (SSS) and conduction defects. Recently, this channel protein has been also linked to structural heart diseases such as dilated cardiomyopathy (DCM).
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Affiliation(s)
| | - Adrien Moreau
- Centre de recherche; Institut universitaire en santé mentale de Québec; Quebec City, QC Canada
| | - Mohamed Chahine
- Centre de recherche; Institut universitaire en santé mentale de Québec; Quebec City, QC Canada; Department of Medicine; Université Laval; Quebec City, QC Canada
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44
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Zeng Z, Zhou J, Hou Y, Liang X, Zhang Z, Xu X, Xie Q, Li W, Huang Z. Electrophysiological characteristics of a SCN5A voltage sensors mutation R1629Q associated with Brugada syndrome. PLoS One 2013; 8:e78382. [PMID: 24167619 PMCID: PMC3805610 DOI: 10.1371/journal.pone.0078382] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2013] [Accepted: 09/14/2013] [Indexed: 12/18/2022] Open
Abstract
Brugada syndrome (BrS) is an inherited arrhythmogenic syndrome leading to sudden cardiac death, partially associated with autosomal dominant mutations in SCN5A, which encodes the cardiac sodium channel alpha-subunit (Nav1.5). To date some SCN5A mutations related with BrS have been identified in voltage sensor of Nav1.5. Here, we describe a dominant missense mutation (R1629Q) localized in the fourth segment of domain IV region (DIV-S4) in a Chinese Han family. The mutation was identified by direct sequencing of SCN5A from the proband's DNA. Co-expression of Wild-type (WT) or R1629Q Nav1.5 channel and hβ1 subunit were achieved in human embryonic kidney cells by transient transfection. Sodium currents were recorded using whole cell patch-clamp protocols. No significant changes between WT and R1629Q currents were observed in current density or steady-state activation. However, hyperpolarized shift of steady-state inactivation curve was identified in cells expressing R1629Q channel (WT: V1/2 = -81.1 ± 1.3 mV, n = 13; R1629Q: V1/2 = -101.7 ± 1.2 mV, n = 18). Moreover, R1629Q channel showed enhanced intermediate inactivation and prolonged recovery time from inactivation. In summary, this study reveals that R1629Q mutation causes a distinct loss-of-function of the channel due to alter its electrophysiological characteristics, and facilitates our understanding of biophysical mechanisms of BrS.
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Affiliation(s)
- Zhipeng Zeng
- Department of Cardiology, the First Affiliated Hospital of Xiamen University, Xiamen, China
| | - Jieqiong Zhou
- Department of Cardiology, the First Affiliated Hospital of Xiamen University, Xiamen, China
| | - Yuxi Hou
- Department of Cardiology, the First Affiliated Hospital of Xiamen University, Xiamen, China
| | - Xiaojing Liang
- Department of Cardiology, the First Affiliated Hospital of Xiamen University, Xiamen, China
| | - Ziguan Zhang
- Department of Cardiology, the First Affiliated Hospital of Xiamen University, Xiamen, China
| | - Xuejing Xu
- Department of Cardiology, the First Affiliated Hospital of Xiamen University, Xiamen, China
| | - Qiang Xie
- Department of Cardiology, the First Affiliated Hospital of Xiamen University, Xiamen, China
| | - Weihua Li
- Department of Cardiology, the First Affiliated Hospital of Xiamen University, Xiamen, China
- * E-mail: (ZH); (WL)
| | - Zhengrong Huang
- Department of Cardiology, the First Affiliated Hospital of Xiamen University, Xiamen, China
- * E-mail: (ZH); (WL)
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45
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R222Q SCN5A Mutation Is Associated With Reversible Ventricular Ectopy and Dilated Cardiomyopathy. J Am Coll Cardiol 2012; 60:1566-73. [DOI: 10.1016/j.jacc.2012.05.050] [Citation(s) in RCA: 99] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/09/2011] [Revised: 04/26/2012] [Accepted: 05/01/2012] [Indexed: 11/21/2022]
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46
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How insensitive … How a mutation in the SCN5A voltage sensor leads to clinical arrhythmia. Heart Rhythm 2012; 9:1689-90. [DOI: 10.1016/j.hrthm.2012.07.020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/10/2012] [Indexed: 11/17/2022]
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