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Li T, Marashly Q, Kim JA, Li N, Chelu MG. Cardiac conduction diseases: understanding the molecular mechanisms to uncover targets for future treatments. Expert Opin Ther Targets 2024; 28:385-400. [PMID: 38700451 DOI: 10.1080/14728222.2024.2351501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2023] [Accepted: 05/01/2024] [Indexed: 05/05/2024]
Abstract
INTRODUCTION The cardiac conduction system (CCS) is crucial for maintaining adequate cardiac frequency at rest and modulation during exercise. Furthermore, the atrioventricular node and His-Purkinje system are essential for maintaining atrioventricular and interventricular synchrony and consequently maintaining an adequate cardiac output. AREAS COVERED In this review article, we examine the anatomy, physiology, and pathophysiology of the CCS. We then discuss in detail the most common genetic mutations and the molecular mechanisms of cardiac conduction disease (CCD) and provide our perspectives on future research and therapeutic opportunities in this field. EXPERT OPINION Significant advancement has been made in understanding the molecular mechanisms of CCD, including the recognition of the heterogeneous signaling at the subcellular levels of sinoatrial node, the involvement of inflammatory and autoimmune mechanisms, and the potential impact of epigenetic regulations on CCD. However, the current treatment of CCD manifested as bradycardia still relies primarily on cardiovascular implantable electronic devices (CIEDs). On the other hand, an If specific inhibitor was developed to treat inappropriate sinus tachycardia and sinus tachycardia in heart failure patients with reduced ejection fraction. More work is needed to translate current knowledge into pharmacologic or genetic interventions for the management of CCDs.
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Affiliation(s)
- Tingting Li
- Department of Medicine (Section of Cardiovascular Research), Baylor College of Medicine, Houston, TX, USA
- Cardiovascular Research Institute, Baylor College of Medicine, Houston, TX, USA
| | - Qussay Marashly
- Department of Cardiology, Montefiore Medical Center, New York, NY, USA
| | - Jitae A Kim
- Division of CardiovasculMedicine, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY, USA
| | - Na Li
- Department of Medicine (Section of Cardiovascular Research), Baylor College of Medicine, Houston, TX, USA
- Cardiovascular Research Institute, Baylor College of Medicine, Houston, TX, USA
| | - Mihail G Chelu
- Cardiovascular Research Institute, Baylor College of Medicine, Houston, TX, USA
- Department of Medicine (Division of Cardiology), Baylor College of Medicine, Houston, TX, USA
- Division of Cardiology, Baylor St. Luke's Medical Center, Houston, TX, USA
- Division of Cardiology, Texas Heart Institute, Houston, TX, USA
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Stevens TL, Coles S, Sturm AC, Hoover CA, Borzok MA, Mohler PJ, El Refaey M. Molecular Pathways and Animal Models of Arrhythmias. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2024; 1441:1057-1090. [PMID: 38884769 DOI: 10.1007/978-3-031-44087-8_67] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2024]
Abstract
Arrhythmias account for over 300,000 annual deaths in the United States, and approximately half of all deaths are associated with heart disease. Mechanisms underlying arrhythmia risk are complex; however, work in humans and animal models over the past 25 years has identified a host of molecular pathways linked with both arrhythmia substrates and triggers. This chapter will focus on select arrhythmia pathways solved by linking human clinical and genetic data with animal models.
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Affiliation(s)
- Tyler L Stevens
- The Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH, USA
- Department of Physiology and Cell Biology, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Sara Coles
- Division of Cardiology, Department of Medicine, Duke University Medical Center, Durham, NC, USA
| | - Amy C Sturm
- Genomic Medicine Institute, 23andMe, Sunnyvale, CA, USA
| | - Catherine A Hoover
- Department of Biochemistry, Chemistry, Engineering and Physics, Commonwealth University of Pennsylvania, Mansfield, PA, USA
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ, USA
| | - Maegen A Borzok
- Department of Biochemistry, Chemistry, Engineering and Physics, Commonwealth University of Pennsylvania, Mansfield, PA, USA
| | - Peter J Mohler
- The Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH, USA
- Department of Physiology and Cell Biology, The Ohio State University Wexner Medical Center, Columbus, OH, USA
- Department of Internal Medicine, Division of Cardiovascular Medicine, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Mona El Refaey
- The Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH, USA.
- Department of Surgery, Division of Cardiac Surgery, The Ohio State University Wexner Medical Center, Columbus, OH, USA.
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3
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Bersell KR, Yang T, Mosley JD, Glazer AM, Hale AT, Kryshtal DO, Kim K, Steimle JD, Brown JD, Salem JE, Campbell CC, Hong CC, Wells QS, Johnson AN, Short L, Blair MA, Behr ER, Petropoulou E, Jamshidi Y, Benson MD, Keyes MJ, Ngo D, Vasan RS, Yang Q, Gerszten RE, Shaffer C, Parikh S, Sheng Q, Kannankeril PJ, Moskowitz IP, York JD, Wang TJ, Knollmann BC, Roden DM. Transcriptional Dysregulation Underlies Both Monogenic Arrhythmia Syndrome and Common Modifiers of Cardiac Repolarization. Circulation 2023; 147:824-840. [PMID: 36524479 PMCID: PMC9992308 DOI: 10.1161/circulationaha.122.062193] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Accepted: 11/03/2022] [Indexed: 12/23/2022]
Abstract
BACKGROUND Brugada syndrome (BrS) is an inherited arrhythmia syndrome caused by loss-of-function variants in the cardiac sodium channel gene SCN5A (sodium voltage-gated channel alpha subunit 5) in ≈20% of subjects. We identified a family with 4 individuals diagnosed with BrS harboring the rare G145R missense variant in the cardiac transcription factor TBX5 (T-box transcription factor 5) and no SCN5A variant. METHODS We generated induced pluripotent stem cells (iPSCs) from 2 members of a family carrying TBX5-G145R and diagnosed with Brugada syndrome. After differentiation to iPSC-derived cardiomyocytes (iPSC-CMs), electrophysiologic characteristics were assessed by voltage- and current-clamp experiments (n=9 to 21 cells per group) and transcriptional differences by RNA sequencing (n=3 samples per group), and compared with iPSC-CMs in which G145R was corrected by CRISPR/Cas9 approaches. The role of platelet-derived growth factor (PDGF)/phosphoinositide 3-kinase (PI3K) pathway was elucidated by small molecule perturbation. The rate-corrected QT (QTc) interval association with serum PDGF was tested in the Framingham Heart Study cohort (n=1893 individuals). RESULTS TBX5-G145R reduced transcriptional activity and caused multiple electrophysiologic abnormalities, including decreased peak and enhanced "late" cardiac sodium current (INa), which were entirely corrected by editing G145R to wild-type. Transcriptional profiling and functional assays in genome-unedited and -edited iPSC-CMs showed direct SCN5A down-regulation caused decreased peak INa, and that reduced PDGF receptor (PDGFRA [platelet-derived growth factor receptor α]) expression and blunted signal transduction to PI3K was implicated in enhanced late INa. Tbx5 regulation of the PDGF axis increased arrhythmia risk due to disruption of PDGF signaling and was conserved in murine model systems. PDGF receptor blockade markedly prolonged normal iPSC-CM action potentials and plasma levels of PDGF in the Framingham Heart Study were inversely correlated with the QTc interval (P<0.001). CONCLUSIONS These results not only establish decreased SCN5A transcription by the TBX5 variant as a cause of BrS, but also reveal a new general transcriptional mechanism of arrhythmogenesis of enhanced late sodium current caused by reduced PDGF receptor-mediated PI3K signaling.
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Affiliation(s)
- Kevin R Bersell
- Departments of Pharmacology (K.R.B., A.M.G., D.O.K., K.K., J-E.S., C.C.C., Q.S.W., S.P., B.C.K., D.M.R.), Vanderbilt University, Nashville, TN
| | - Tao Yang
- Medicine (T.Y., J.D.M., J.D.B., J-E.S., Q.S.W., L.S., M.A.B., C.S., T.J.W., B.C.K., D.M.R.), Vanderbilt University, Nashville, TN
| | - Jonathan D Mosley
- Departments of Pharmacology (K.R.B., A.M.G., D.O.K., K.K., J-E.S., C.C.C., Q.S.W., S.P., B.C.K., D.M.R.), Vanderbilt University, Nashville, TN
| | - Andrew M Glazer
- Departments of Pharmacology (K.R.B., A.M.G., D.O.K., K.K., J-E.S., C.C.C., Q.S.W., S.P., B.C.K., D.M.R.), Vanderbilt University, Nashville, TN
| | - Andrew T Hale
- Biochemistry (A.T.H., J.D.Y.), Vanderbilt University, Nashville, TN
| | - Dmytro O Kryshtal
- Departments of Pharmacology (K.R.B., A.M.G., D.O.K., K.K., J-E.S., C.C.C., Q.S.W., S.P., B.C.K., D.M.R.), Vanderbilt University, Nashville, TN
| | - Kyungsoo Kim
- Departments of Pharmacology (K.R.B., A.M.G., D.O.K., K.K., J-E.S., C.C.C., Q.S.W., S.P., B.C.K., D.M.R.), Vanderbilt University, Nashville, TN
| | - Jeffrey D Steimle
- Departments of Pediatrics, Pathology, and Human Genetics, University of Chicago, IL (J.D.S., I.P.M.)
| | - Jonathan D Brown
- Medicine (T.Y., J.D.M., J.D.B., J-E.S., Q.S.W., L.S., M.A.B., C.S., T.J.W., B.C.K., D.M.R.), Vanderbilt University, Nashville, TN
| | - Joe-Elie Salem
- Departments of Pharmacology (K.R.B., A.M.G., D.O.K., K.K., J-E.S., C.C.C., Q.S.W., S.P., B.C.K., D.M.R.), Vanderbilt University, Nashville, TN
- Medicine (T.Y., J.D.M., J.D.B., J-E.S., Q.S.W., L.S., M.A.B., C.S., T.J.W., B.C.K., D.M.R.), Vanderbilt University, Nashville, TN
- Assistance Publique - Hôpitaux de Paris, Pitié-Salpêtrière Hospital, Department of Pharmacology, CIC-1901, Sorbonne University, Paris, France (J-E.S.)
- Sorbonne Universités, UPMC Univ Paris 06, Faculty of Medicine, France (J-E.S.)
| | - Courtney C Campbell
- Departments of Pharmacology (K.R.B., A.M.G., D.O.K., K.K., J-E.S., C.C.C., Q.S.W., S.P., B.C.K., D.M.R.), Vanderbilt University, Nashville, TN
| | - Charles C Hong
- Department of Medicine, University of Maryland School of Medicine, Baltimore (C.C.H.)
| | - Quinn S Wells
- Departments of Pharmacology (K.R.B., A.M.G., D.O.K., K.K., J-E.S., C.C.C., Q.S.W., S.P., B.C.K., D.M.R.), Vanderbilt University, Nashville, TN
- Medicine (T.Y., J.D.M., J.D.B., J-E.S., Q.S.W., L.S., M.A.B., C.S., T.J.W., B.C.K., D.M.R.), Vanderbilt University, Nashville, TN
- Biomedical Informatics (Q.S.W., D.M.R.), Vanderbilt University, Nashville, TN
| | - Amanda N Johnson
- Molecular Physiology and Biophysics (A.N.J.), Vanderbilt University, Nashville, TN
| | - Laura Short
- Medicine (T.Y., J.D.M., J.D.B., J-E.S., Q.S.W., L.S., M.A.B., C.S., T.J.W., B.C.K., D.M.R.), Vanderbilt University, Nashville, TN
| | - Marcia A Blair
- Medicine (T.Y., J.D.M., J.D.B., J-E.S., Q.S.W., L.S., M.A.B., C.S., T.J.W., B.C.K., D.M.R.), Vanderbilt University, Nashville, TN
| | | | - Evmorfia Petropoulou
- Cardiology Clinical Academic Group, Molecular and Clinical Sciences Institute, St George's, University of London and St George's University Hospitals National Health Service Foundation Trust, London, UK (E.P., Y.J.)
| | - Yalda Jamshidi
- Cardiology Clinical Academic Group, Molecular and Clinical Sciences Institute, St George's, University of London and St George's University Hospitals National Health Service Foundation Trust, London, UK (E.P., Y.J.)
| | - Mark D Benson
- Cardiovascular Research Center (E.J.B., M.D.B., M.J.K., R.E.G.), Beth Israel Deaconess Hospital, Boston, MA
- Division of Cardiovascular Medicine, Brigham and Women's Hospital, Boston, MA (M.D.B.)
| | - Michelle J Keyes
- Cardiovascular Research Center (E.J.B., M.D.B., M.J.K., R.E.G.), Beth Israel Deaconess Hospital, Boston, MA
| | - Debby Ngo
- Division of Pulmonary and Cardiovascular Medicine (D.N., R.E.G.), Beth Israel Deaconess Hospital, Boston, MA
| | | | - Qiong Yang
- Boston University School of Medicine, MA (R.S.V., Q.Y.)
| | - Robert E Gerszten
- Cardiovascular Research Center (E.J.B., M.D.B., M.J.K., R.E.G.), Beth Israel Deaconess Hospital, Boston, MA
- Division of Pulmonary and Cardiovascular Medicine (D.N., R.E.G.), Beth Israel Deaconess Hospital, Boston, MA
| | - Christian Shaffer
- Medicine (T.Y., J.D.M., J.D.B., J-E.S., Q.S.W., L.S., M.A.B., C.S., T.J.W., B.C.K., D.M.R.), Vanderbilt University, Nashville, TN
| | - Shan Parikh
- Departments of Pharmacology (K.R.B., A.M.G., D.O.K., K.K., J-E.S., C.C.C., Q.S.W., S.P., B.C.K., D.M.R.), Vanderbilt University, Nashville, TN
| | | | | | - Ivan P Moskowitz
- Departments of Pediatrics, Pathology, and Human Genetics, University of Chicago, IL (J.D.S., I.P.M.)
| | - John D York
- Biochemistry (A.T.H., J.D.Y.), Vanderbilt University, Nashville, TN
| | - Thomas J Wang
- Medicine (T.Y., J.D.M., J.D.B., J-E.S., Q.S.W., L.S., M.A.B., C.S., T.J.W., B.C.K., D.M.R.), Vanderbilt University, Nashville, TN
| | - Bjorn C Knollmann
- Departments of Pharmacology (K.R.B., A.M.G., D.O.K., K.K., J-E.S., C.C.C., Q.S.W., S.P., B.C.K., D.M.R.), Vanderbilt University, Nashville, TN
- Medicine (T.Y., J.D.M., J.D.B., J-E.S., Q.S.W., L.S., M.A.B., C.S., T.J.W., B.C.K., D.M.R.), Vanderbilt University, Nashville, TN
| | - Dan M Roden
- Departments of Pharmacology (K.R.B., A.M.G., D.O.K., K.K., J-E.S., C.C.C., Q.S.W., S.P., B.C.K., D.M.R.), Vanderbilt University, Nashville, TN
- Medicine (T.Y., J.D.M., J.D.B., J-E.S., Q.S.W., L.S., M.A.B., C.S., T.J.W., B.C.K., D.M.R.), Vanderbilt University, Nashville, TN
- Biomedical Informatics (Q.S.W., D.M.R.), Vanderbilt University, Nashville, TN
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Lin L, Li K, Tian B, Jia M, Wang Q, Xu C, Xiong L, Wang Q, Zeng Y, Wang P. Two Novel Functional Mutations in Promoter Region of SCN3B Gene Associated with Atrial Fibrillation. Life (Basel) 2022; 12:life12111794. [PMID: 36362949 PMCID: PMC9698146 DOI: 10.3390/life12111794] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Revised: 11/01/2022] [Accepted: 11/03/2022] [Indexed: 11/09/2022] Open
Abstract
The sodium voltage-gated channel beta subunit 3 (SCN3B) plays a crucial role in electrically excitable cells and conduction tissue in the heart. Some previous studies have established that genetic modification in sodium voltage-channel genes encoding for the cardiac β-subunits, such as SCN1B, SCN2B, SCN3B and SCN4B, can result in atrial fibrillation (AF). In the current study, we identified two rare variants in 5′UTR (NM_018400.4: c.-324C>A, rs976125894 and NM_018400.4: c.-303C>T, rs1284768362) of SCN3B in two unrelated lone AF patients. Our further functional studies discovered that one of them, the A allele of c.-324C>A (rs976125894), can improve transcriptional activity and may raise SCN3B expression levels. The A allele of c.-324C>A (rs976125894) has higher transcriptional activity when it interacts with GATA4, as we confirmed transcription factor GATA4 is a regulator of SCN3B. To the best of our knowledge, the current study is the first to demonstrate that the gain-of-function mutation of SCN3B can produce AF and the first to link a mutation occurring in the non-coding 5′UTR region of SCN3B to lone AF. The work also offers empirical proof that GATA4 is a critical regulator of SCN3B gene regulation. Our findings may serve as an encyclopedia for AF susceptibility variants and can also provide insight into the investigation of the functional mechanisms behind AF variants discovered by genetic methods.
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Affiliation(s)
- Liyan Lin
- Department of Clinical Laboratory, Liyuan Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430077, China
| | - Ke Li
- Key Laboratory of Molecular Biophysics of the Ministry of Education, Cardio-X Institute, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, China
- Human Genome Research Center, College of Life and Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Beijia Tian
- Key Laboratory of Molecular Biophysics of the Ministry of Education, Cardio-X Institute, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, China
- Human Genome Research Center, College of Life and Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Mengru Jia
- Key Laboratory of Molecular Biophysics of the Ministry of Education, Cardio-X Institute, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, China
- Human Genome Research Center, College of Life and Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Qianyan Wang
- Liyuan Cardiovascular Center, Liyuan Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430077, China
| | - Chengqi Xu
- Key Laboratory of Molecular Biophysics of the Ministry of Education, Cardio-X Institute, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, China
- Human Genome Research Center, College of Life and Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Liang Xiong
- Department of Clinical Laboratory, Liyuan Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430077, China
| | - Qing Wang
- Key Laboratory of Molecular Biophysics of the Ministry of Education, Cardio-X Institute, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, China
- Human Genome Research Center, College of Life and Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Yali Zeng
- Department of Clinical Laboratory, Liyuan Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430077, China
- Correspondence: (Y.Z.); (P.W.)
| | - Pengyun Wang
- Department of Clinical Laboratory, Liyuan Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430077, China
- Correspondence: (Y.Z.); (P.W.)
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Zhu Z, Bolt E, Newmaster K, Osei-Bonsu W, Cohen S, Cuddapah VA, Gupta S, Paudel S, Samanta D, Dang LT, Carney PR, Naik S. SCN1B Genetic Variants: A Review of the Spectrum of Clinical Phenotypes and a Report of Early Myoclonic Encephalopathy. CHILDREN (BASEL, SWITZERLAND) 2022; 9:children9101507. [PMID: 36291443 PMCID: PMC9600564 DOI: 10.3390/children9101507] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2022] [Revised: 09/26/2022] [Accepted: 09/30/2022] [Indexed: 11/06/2022]
Abstract
Background: Pathogenic variants in SCN1B, the gene encoding voltage-gated sodium channel b1/b1B subunits are associated with a spectrum of epileptic disorders. This study describes a child with early myoclonic encephalopathy and a compound heterozygous variant in the SCN1B gene (p.Arg85Cys and c.3G>C/p.Met1), along with the child’s clinical response to anti-seizure medications (ASMs) and the ketogenic diet. We reviewed the current clinical literature pertinent to SCN1B-related epilepsy. Methods: We described the evaluation and management of a patient with SCN1B-related developmental and epileptic encephalopathy (DEE). We used the Medline and Pubmed databases to review the various neurological manifestations associated with SCN1B genetic variants, and summarize the functional studies performed on SCN1B variants. Results: We identified 20 families and six individuals (including the index case described herein) reported to have SCN1B-related epilepsy. Individuals with monoallelic pathogenic variants in SCN1B often present with genetic epilepsy with febrile seizures plus (GEFS+), while those with biallelic pathogenic variants may present with developmental and epileptic encephalopathy (DEE). Individuals with DEE present with seizures of various semiologies (commonly myoclonic seizures) and status epilepticus at early infancy and are treated with various antiseizure medications. In our index case, adjunctive fenfluramine was started at 8 months of age at 0.2 mg/kg/day with gradual incremental increases to the final dose of 0.7 mg/kg/day over 5 weeks. Fenfluramine was effective in the treatment of seizures, resulting in a 50% reduction in myoclonic seizures, status epilepticus, and generalized tonic-clonic seizures, as well as a 70−90% reduction in focal seizures, with no significant adverse effects. Following the initiation of fenfluramine at eight months of age, there was also a 50% reduction in the rate of hospitalizations. Conclusions: SCN1B pathogenic variants cause epilepsy and neurodevelopmental impairment with variable expressivity and incomplete penetrance. The severity of disease is associated with the zygosity of the pathogenic variants. Biallelic variants in SCN1B can result in early myoclonic encephalopathy, and adjunctive treatment with fenfluramine may be an effective treatment for SCN1B-related DEE. Further research on the efficacy and safety of using newer ASMs, such as fenfluramine in patients under the age of 2 years is needed.
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Affiliation(s)
- Zahra Zhu
- College of Medicine, Penn State University, Hershey, PA 17033, USA
| | - Elizabeth Bolt
- College of Medicine, Penn State University, Hershey, PA 17033, USA
| | - Kyra Newmaster
- College of Medicine, Penn State University, Hershey, PA 17033, USA
| | - Wendy Osei-Bonsu
- College of Medicine, Penn State University, Hershey, PA 17033, USA
| | - Stacey Cohen
- Epilepsy Neurogenetics Initiative, Division of Neurology, Children’s Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Vishnu Anand Cuddapah
- Epilepsy Neurogenetics Initiative, Division of Neurology, Children’s Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Siddharth Gupta
- Kennedy Krieger Institute, Department of Neurology, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Sita Paudel
- Department of Pediatrics and Neurology, Penn State Health Milton Hershey Medical Center, Hershey, PA 17033, USA
| | - Debopam Samanta
- Division of Pediatric Neurology, Arkansas Children’s Hospital, Little Rock, AR 72202, USA
| | - Louis T. Dang
- Department of Pediatrics, Division of Pediatric Neurology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Paul R. Carney
- Pediatric Neurology Division, University of Missouri Health Care, Columbia, MO 65212, USA
- Correspondence: (P.R.C.); (S.N.)
| | - Sunil Naik
- Department of Pediatrics and Neurology, Penn State Health Milton Hershey Medical Center, Hershey, PA 17033, USA
- Correspondence: (P.R.C.); (S.N.)
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Bidzimou MTK, Landstrom AP. From diagnostic testing to precision medicine: the evolving role of genomics in cardiac channelopathies and cardiomyopathies in children. Curr Opin Genet Dev 2022; 76:101978. [PMID: 36058060 PMCID: PMC9733798 DOI: 10.1016/j.gde.2022.101978] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 07/04/2022] [Accepted: 08/01/2022] [Indexed: 12/13/2022]
Abstract
Pediatric sudden cardiac death (SCD) is the sudden unexpected death of a child or adolescent due to a presumed cardiac etiology. Heritable causes of pediatric SCD are predominantly cardiomyopathies and cardiac ion channelopathies. This review illustrates recent advances in determining the genetic cause of established and emerging channelopathies and cardiomyopathies, and how broader genomic sequencing is uncovering complex interactions between genetic architecture and disease manifestation. We discuss innovative models and experimental platforms for resolving the variant of uncertain significance as both the variants and genes associated with disease continue to evolve. Finally, we highlight the growing problem of incidentally identified variants in cardiovascular disease-causing genes and review innovative methods to determining whether these variants may ultimately result in penetrant disease. Overall, we seek to illustrate both the promise and inherent challenges in bridging the traditional role for genetics in diagnosing cardiomyopathies and channelopathies to one of true risk-predictive precision medicine.
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Affiliation(s)
- Minu-Tshyeto K Bidzimou
- Department of Cell Biology, Duke University School of Medicine, Durham, NC, United States. https://twitter.com/@MBidzimou
| | - Andrew P Landstrom
- Department of Cell Biology, Duke University School of Medicine, Durham, NC, United States; Department of Pediatrics, Division of Pediatric Cardiology, Duke University School of Medicine, Durham, NC, United States.
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Hodges SL, Bouza AA, Isom LL. Therapeutic Potential of Targeting Regulated Intramembrane Proteolysis Mechanisms of Voltage-Gated Ion Channel Subunits and Cell Adhesion Molecules. Pharmacol Rev 2022; 74:1028-1048. [PMID: 36113879 PMCID: PMC9553118 DOI: 10.1124/pharmrev.121.000340] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Accepted: 05/13/2022] [Indexed: 10/03/2023] Open
Abstract
Several integral membrane proteins undergo regulated intramembrane proteolysis (RIP), a tightly controlled process through which cells transmit information across and between intracellular compartments. RIP generates biologically active peptides by a series of proteolytic cleavage events carried out by two primary groups of enzymes: sheddases and intramembrane-cleaving proteases (iCLiPs). Following RIP, fragments of both pore-forming and non-pore-forming ion channel subunits, as well as immunoglobulin super family (IgSF) members, have been shown to translocate to the nucleus to function in transcriptional regulation. As an example, the voltage-gated sodium channel β1 subunit, which is also an IgSF-cell adhesion molecule (CAM), is a substrate for RIP. β1 RIP results in generation of a soluble intracellular domain, which can regulate gene expression in the nucleus. In this review, we discuss the proposed RIP mechanisms of voltage-gated sodium, potassium, and calcium channel subunits as well as the roles of their generated proteolytic products in the nucleus. We also discuss other RIP substrates that are cleaved by similar sheddases and iCLiPs, such as IgSF macromolecules, including CAMs, whose proteolytically generated fragments function in the nucleus. Importantly, dysfunctional RIP mechanisms are linked to human disease. Thus, we will also review how understanding RIP events and subsequent signaling processes involving ion channel subunits and IgSF proteins may lead to the discovery of novel therapeutic targets. SIGNIFICANCE STATEMENT: Several ion channel subunits and immunoglobulin superfamily molecules have been identified as substrates of regulated intramembrane proteolysis (RIP). This signal transduction mechanism, which generates polypeptide fragments that translocate to the nucleus, is an important regulator of gene transcription. RIP may impact diseases of excitability, including epilepsy, cardiac arrhythmia, and sudden death syndromes. A thorough understanding of the role of RIP in gene regulation is critical as it may reveal novel therapeutic strategies for the treatment of previously intractable diseases.
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Affiliation(s)
- Samantha L Hodges
- Departments of Pharmacology (S.L.H., A.A.B., L.L.I.), Neurology (L.L.I.), and Molecular & Integrative Physiology (L.L.I.), University of Michigan Medical School, Ann Arbor, Michigan
| | - Alexandra A Bouza
- Departments of Pharmacology (S.L.H., A.A.B., L.L.I.), Neurology (L.L.I.), and Molecular & Integrative Physiology (L.L.I.), University of Michigan Medical School, Ann Arbor, Michigan
| | - Lori L Isom
- Departments of Pharmacology (S.L.H., A.A.B., L.L.I.), Neurology (L.L.I.), and Molecular & Integrative Physiology (L.L.I.), University of Michigan Medical School, Ann Arbor, Michigan
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8
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Concealed Substrates in Brugada Syndrome: Isolated Channelopathy or Associated Cardiomyopathy? Genes (Basel) 2022; 13:genes13101755. [DOI: 10.3390/genes13101755] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2022] [Revised: 09/20/2022] [Accepted: 09/23/2022] [Indexed: 11/17/2022] Open
Abstract
Brugada syndrome (BrS) is an inherited autosomal dominant genetic disorder responsible for sudden cardiac death from malignant ventricular arrhythmia. The term “channelopathy” is nowadays used to classify BrS as a purely electrical disease, mainly occurring secondarily to loss-of-function mutations in the α subunit of the cardiac sodium channel protein Nav1.5. In this setting, arrhythmic manifestations of the disease have been reported in the absence of any apparent structural heart disease or cardiomyopathy. Over the last few years, however, a consistent amount of evidence has grown in support of myocardial structural and functional abnormalities in patients with BrS. In detail, abnormal ventricular dimensions, either systolic or diastolic dysfunctions, regional wall motion abnormalities, myocardial fibrosis, and active inflammatory foci have been frequently described, pointing to alternative mechanisms of arrhythmogenesis which challenge the definition of channelopathy. The present review aims to depict the status of the art of concealed arrhythmogenic substrates in BrS, often resulting from an advanced and multimodal diagnostic workup, to foster future preclinical and clinical research in support of the cardiomyopathic nature of the disease.
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9
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Wang M, Tu X. The Genetics and Epigenetics of Ventricular Arrhythmias in Patients Without Structural Heart Disease. Front Cardiovasc Med 2022; 9:891399. [PMID: 35783865 PMCID: PMC9240357 DOI: 10.3389/fcvm.2022.891399] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Accepted: 05/25/2022] [Indexed: 12/19/2022] Open
Abstract
Ventricular arrhythmia without structural heart disease is an arrhythmic disorder that occurs in structurally normal heart and no transient or reversible arrhythmia factors, such as electrolyte disorders and myocardial ischemia. Ventricular arrhythmias without structural heart disease can be induced by multiple factors, including genetics and environment, which involve different genetic and epigenetic regulation. Familial genetic analysis reveals that cardiac ion-channel disorder and dysfunctional calcium handling are two major causes of this type of heart disease. Genome-wide association studies have identified some genetic susceptibility loci associated with ventricular tachycardia and ventricular fibrillation, yet relatively few loci associated with no structural heart disease. The effects of epigenetics on the ventricular arrhythmias susceptibility genes, involving non-coding RNAs, DNA methylation and other regulatory mechanisms, are gradually being revealed. This article aims to review the knowledge of ventricular arrhythmia without structural heart disease in genetics, and summarizes the current state of epigenetic regulation.
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10
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Lee JH, Lee DH, Lee BK, Cho YS, Kim DK, Jung YH. Role of electrocardiogram findings in predicting 48-h mortality in patients with traumatic brain injury. BMC Neurol 2022; 22:190. [PMID: 35610594 PMCID: PMC9128249 DOI: 10.1186/s12883-022-02717-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Accepted: 05/18/2022] [Indexed: 11/17/2022] Open
Abstract
OBJECTIVE Electrocardiogram (ECG) patterns can change, especially in patients with central nervous system disorders such as spontaneous subarachnoid hemorrhage. However, the association between the prognosis of traumatic brain injury (TBI) and ECG findings is unknown. Therefore, this study aimed to compare and to analyze ECG findings to predict early mortality in patients with TBI. METHODS This retrospective observational study included patients with severe trauma and TBI who were admitted to the emergency department (ED) between January 2018 and December 2020. TBI was defined as an abbreviated injury scale score of the head of ≥3. We examined ECG findings, including PR prolongation (≥ 200 ms), QRS complex widening (≥ 120 ms), corrected QT interval prolongation (QTP, ≥ 480 ms), ST-segment elevation, and ST-segment depression (STD) at ED arrival. The primary outcome was 48-h mortality. RESULTS Of the total patients with TBI, 1024 patients were included in this study and 48-h mortality occurred in 89 patients (8.7%). In multivariate analysis, QTP (odds ratio [OR], 2.017; confidence interval [CI], 1.203-3.382) and STD (OR, 8.428; 95% CI, 5.019-14.152) were independently associated with 48-h mortality in patients with TBI. The areas under the curve (AUCs) of the revised trauma score (RTS), injury severity score (ISS), QTP, STD, and the combination of QTP and STD were 0.790 (95% CI, 0.764-0.815), 0.632 (95% CI, 0.602-0.662), 0.605 (95% CI, 0.574-0.635), 0.723 (95% CI, 0.695-0.750), and 0.786 (95% CI, 0.759-0.811), respectively. The AUC of the combination of QTP and STD significantly differed from that of ISS, QTP, and STD, but not RTS. CONCLUSION Based on the ECG findings, QTP and STD were associated with 48-h mortality in patients with TBI.
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Affiliation(s)
- Ji Ho Lee
- Department of Emergency Medicine, Chonnam National University Hospital, 42 Jebong-ro, Donggu, Gwangju, Republic of Korea
| | - Dong Hun Lee
- Department of Emergency Medicine, Chonnam National University Hospital, 42 Jebong-ro, Donggu, Gwangju, Republic of Korea.
| | - Byung Kook Lee
- Department of Emergency Medicine, Chonnam National University Hospital, 42 Jebong-ro, Donggu, Gwangju, Republic of Korea
- Department of Emergency Medicine, Chonnam National University Medical School, 160 Baekseo-ro, Dong-gu, Gwangju, Republic of Korea
| | - Yong Soo Cho
- Department of Emergency Medicine, Chonnam National University Hospital, 42 Jebong-ro, Donggu, Gwangju, Republic of Korea
| | - Dong Ki Kim
- Department of Emergency Medicine, Chonnam National University Hospital, 42 Jebong-ro, Donggu, Gwangju, Republic of Korea
| | - Yong Hun Jung
- Department of Emergency Medicine, Chonnam National University Hospital, 42 Jebong-ro, Donggu, Gwangju, Republic of Korea
- Department of Emergency Medicine, Chonnam National University Medical School, 160 Baekseo-ro, Dong-gu, Gwangju, Republic of Korea
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11
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Daimi H, Lozano-Velasco E, Aranega A, Franco D. Genomic and Non-Genomic Regulatory Mechanisms of the Cardiac Sodium Channel in Cardiac Arrhythmias. Int J Mol Sci 2022; 23:1381. [PMID: 35163304 PMCID: PMC8835759 DOI: 10.3390/ijms23031381] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Revised: 12/30/2021] [Accepted: 01/06/2022] [Indexed: 12/19/2022] Open
Abstract
Nav1.5 is the predominant cardiac sodium channel subtype, encoded by the SCN5A gene, which is involved in the initiation and conduction of action potentials throughout the heart. Along its biosynthesis process, Nav1.5 undergoes strict genomic and non-genomic regulatory and quality control steps that allow only newly synthesized channels to reach their final membrane destination and carry out their electrophysiological role. These regulatory pathways are ensured by distinct interacting proteins that accompany the nascent Nav1.5 protein along with different subcellular organelles. Defects on a large number of these pathways have a tremendous impact on Nav1.5 functionality and are thus intimately linked to cardiac arrhythmias. In the present review, we provide current state-of-the-art information on the molecular events that regulate SCN5A/Nav1.5 and the cardiac channelopathies associated with defects in these pathways.
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Affiliation(s)
- Houria Daimi
- Biochemistry and Molecular Biology Laboratory, Faculty of Pharmacy, University of Monastir, Monastir 5000, Tunisia
| | - Estefanía Lozano-Velasco
- Department of Experimental Biology, University of Jaen, 23071 Jaen, Spain; (E.L.-V.); (A.A.); (D.F.)
- Medina Foundation, Technology Park of Health Sciences, Av. del Conocimiento, 34, 18016 Granada, Spain
| | - Amelia Aranega
- Department of Experimental Biology, University of Jaen, 23071 Jaen, Spain; (E.L.-V.); (A.A.); (D.F.)
- Medina Foundation, Technology Park of Health Sciences, Av. del Conocimiento, 34, 18016 Granada, Spain
| | - Diego Franco
- Department of Experimental Biology, University of Jaen, 23071 Jaen, Spain; (E.L.-V.); (A.A.); (D.F.)
- Medina Foundation, Technology Park of Health Sciences, Av. del Conocimiento, 34, 18016 Granada, Spain
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12
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Gauvrit S, Bossaer J, Lee J, Collins MM. Modeling Human Cardiac Arrhythmias: Insights from Zebrafish. J Cardiovasc Dev Dis 2022; 9:jcdd9010013. [PMID: 35050223 PMCID: PMC8779270 DOI: 10.3390/jcdd9010013] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Revised: 12/23/2021] [Accepted: 12/25/2021] [Indexed: 12/13/2022] Open
Abstract
Cardiac arrhythmia, or irregular heart rhythm, is associated with morbidity and mortality and is described as one of the most important future public health challenges. Therefore, developing new models of cardiac arrhythmia is critical for understanding disease mechanisms, determining genetic underpinnings, and developing new therapeutic strategies. In the last few decades, the zebrafish has emerged as an attractive model to reproduce in vivo human cardiac pathologies, including arrhythmias. Here, we highlight the contribution of zebrafish to the field and discuss the available cardiac arrhythmia models. Further, we outline techniques to assess potential heart rhythm defects in larval and adult zebrafish. As genetic tools in zebrafish continue to bloom, this model will be crucial for functional genomics studies and to develop personalized anti-arrhythmic therapies.
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13
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Chen K, Palagashvili T, Hsu W, Chen Y, Tabakoff B, Hong F, Shih AT, Shih JC. Brain injury and inflammation genes common to a number of neurological diseases and the genes involved in the genesis of GABAnergic neurons are altered in monoamine oxidase B knockout mice. Brain Res 2022; 1774:147724. [PMID: 34780749 PMCID: PMC8638699 DOI: 10.1016/j.brainres.2021.147724] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Revised: 11/03/2021] [Accepted: 11/08/2021] [Indexed: 01/03/2023]
Abstract
Monoamine oxidase B (MAO B) oxidizes trace amine phenylethylamine (PEA), and neurotransmitters serotonin and dopamine in the brain. We reported previously that PEA levels increased significantly in all brain regions, but serotonin and dopamine levels were unchanged in MAO B knockout (KO) mice. PEA and dopamine are both synthesized from phenylalanine by aromatic L-amino acid decarboxylase in dopaminergic neurons in the striatum. A high concentration of PEA in the striatum may cause dopaminergic neuronal death in the absence of MAO B. We isolated the RNA from brain tissue of MAO B KO mice (2-month old) and age-matched wild type (WT) male mice and analyzed the altered genes by Affymetrix microarray. Differentially expressed genes (DEGs) in MAO B KO compared to WT mice were analyzed by Partek Genomics Suite, followed by Ingenuity Pathway Analysis (IPA) to assess their functional relationships. DEGs in MAO B KO mice are involved in brain inflammation and the genesis of GABAnergic neurons. The significant DEGs include four brain injury or inflammation genes (upregulated: Ido1, TSPO, AVP, Tdo2), five gamma-aminobutyric acid (GABA) receptors (down-regulated: GABRA2, GABRA3, GABRB1, GABRB3, GABRG3), five transcription factors related to adult neurogenesis (upregulated: Wnt7b, Hes5; down-regulated: Pax6, Tcf4, Dtna). Altered brain injury and inflammation genes in MAO B knockout mice are involved in various neurological disorders: attention deficit hyperactive disorder, panic disorder, obsessive compulsive disorder, autism, amyotrophic lateral sclerosis, Parkinson's diseases, Alzheimer's disease, bipolar affective disorder. Many were commonly involved in these disorders, indicating that there are overlapping molecular pathways.
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Affiliation(s)
- Kevin Chen
- Department of Pharmacology and Pharmaceutical Sciences, School of Pharmacy, 1985 Zonal Ave., Los Angeles, CA, USA
| | - Tamara Palagashvili
- Department of Pharmacology and Pharmaceutical Sciences, School of Pharmacy, 1985 Zonal Ave., Los Angeles, CA, USA
| | - W Hsu
- Department of Pharmacology and Pharmaceutical Sciences, School of Pharmacy, 1985 Zonal Ave., Los Angeles, CA, USA
| | - Yibu Chen
- Norris Medical Library, University of Southern California, Los Angeles, CA, USA
| | - Boris Tabakoff
- University of Colorado Health Science Center, Denver, CO, USA
| | - Frank Hong
- Department of Pharmacology and Pharmaceutical Sciences, School of Pharmacy, 1985 Zonal Ave., Los Angeles, CA, USA
| | - Abigail T Shih
- Department of Pharmacology and Pharmaceutical Sciences, School of Pharmacy, 1985 Zonal Ave., Los Angeles, CA, USA
| | - Jean C Shih
- Department of Pharmacology and Pharmaceutical Sciences, School of Pharmacy, 1985 Zonal Ave., Los Angeles, CA, USA; Department of Integrative Anatomical Sciences, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA; Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA; USC-Taiwan Center for Translational Research, University of Southern California, Los Angeles CA, USA.
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14
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Angsutararux P, Zhu W, Voelker TL, Silva JR. Molecular Pathology of Sodium Channel Beta-Subunit Variants. Front Pharmacol 2021; 12:761275. [PMID: 34867379 PMCID: PMC8640220 DOI: 10.3389/fphar.2021.761275] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Accepted: 10/28/2021] [Indexed: 12/19/2022] Open
Abstract
The voltage-gated Na+ channel regulates the initiation and propagation of the action potential in excitable cells. The major cardiac isoform NaV1.5, encoded by SCN5A, comprises a monomer with four homologous repeats (I-IV) that each contain a voltage sensing domain (VSD) and pore domain. In native myocytes, NaV1.5 forms a macromolecular complex with NaVβ subunits and other regulatory proteins within the myocyte membrane to maintain normal cardiac function. Disturbance of the NaV complex may manifest as deadly cardiac arrhythmias. Although SCN5A has long been identified as a gene associated with familial atrial fibrillation (AF) and Brugada Syndrome (BrS), other genetic contributors remain poorly understood. Emerging evidence suggests that mutations in the non-covalently interacting NaVβ1 and NaVβ3 are linked to both AF and BrS. Here, we investigated the molecular pathologies of 8 variants in NaVβ1 and NaVβ3. Our results reveal that NaVβ1 and NaVβ3 variants contribute to AF and BrS disease phenotypes by modulating both NaV1.5 expression and gating properties. Most AF-linked variants in the NaVβ1 subunit do not alter the gating kinetics of the sodium channel, but rather modify the channel expression. In contrast, AF-related NaVβ3 variants directly affect channel gating, altering voltage-dependent activation and the time course of recovery from inactivation via the modulation of VSD activation.
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Affiliation(s)
- Paweorn Angsutararux
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, United States
| | - Wandi Zhu
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, United States.,Department of Medicine, Brigham and Women's Hospital, Boston, MA, United States
| | - Taylor L Voelker
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, United States
| | - Jonathan R Silva
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, United States
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15
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Hu RM, Song EJ, Tester DJ, Deschenes I, Ackerman MJ, Makielski JC, Tan BH. Expression defect of the rare variant/Brugada mutation R1512W depends upon the SCN5A splice variant background and can be rescued by mexiletine and the common polymorphism H558R. Channels (Austin) 2021; 15:253-261. [PMID: 33535892 PMCID: PMC7872018 DOI: 10.1080/19336950.2021.1875645] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Revised: 01/08/2021] [Accepted: 01/08/2021] [Indexed: 12/01/2022] Open
Abstract
Background : Mutations in SCN5A that decrease Na current underlie arrhythmia syndromes such as the Brugada syndrome (BrS). SCN5A in humans has two splice variants, one lacking a glutamine at position 1077 (Q1077del) and one containing Q1077. We investigated the effect of splice variant background on loss-of-function and rescue for R1512W, a mutation reported to cause BrS. Methods and results : We made the mutation in both variants and expressed them in HEK-293 cells for voltage-clamp study. After 24 hours of transfection, the current expression level of R1512W was reduced by ~50% in both Q1077del and Q1077 compared to the wild-type (WT) channel, respectively. The activation and inactivation midpoint were not different between WT and mutant channels in both splice variant backgrounds. However, slower time constants of recovery and enhanced intermediate inactivation were observed for R1512W/Q1077 compared with WT-Q1077, while the recovery and intermediate inactivation parameters of R1512W/Q1077del were similar to WT-Q1077del. Furthermore, both mexiletine and the common polymorphism H558R restored peak sodium current (INa) amplitude of the mutant channel by increasing the cell surface expression of SCN5A. Conclusion : These findings provide further evidence that the splice variant affects the molecular phenotype with implications for the clinical phenotype, and they provide insight into the expression defect mechanisms and potential treatment in BrS.
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Affiliation(s)
- Rou-Mu Hu
- Department of Cardiology, Heart Center & Beijing Key Laboratory of Hypertension, Beijing Chaoyang Hospital, Capital Medical University, Beijing, China
- Division of Cardiovascular Medicine, Department of Medicine, University of Wisconsin, Madison, WI, USA
| | - Evelyn J. Song
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - David J. Tester
- Departments of Medicine, Pediatrics, and Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, MN, USA
| | - Isabelle Deschenes
- Department of Physiology and Cell Biology, The Dorothy M. Davis Heart and Lung Research Institute, Frick Center for Heart Failure and Arrhythmia, the Ohio State University, Columbus, OH, USA
| | - Michael J. Ackerman
- Departments of Medicine, Pediatrics, and Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, MN, USA
| | - Jonathan C. Makielski
- Division of Cardiovascular Medicine, Department of Medicine, University of Wisconsin, Madison, WI, USA
| | - Bi-Hua Tan
- Division of Cardiovascular Medicine, Department of Medicine, University of Wisconsin, Madison, WI, USA
- Department of Physiology and Cell Biology, The Dorothy M. Davis Heart and Lung Research Institute, Frick Center for Heart Failure and Arrhythmia, the Ohio State University, Columbus, OH, USA
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16
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Chen L, He Y, Wang X, Ge J, Li H. Ventricular voltage-gated ion channels: Detection, characteristics, mechanisms, and drug safety evaluation. Clin Transl Med 2021; 11:e530. [PMID: 34709746 PMCID: PMC8516344 DOI: 10.1002/ctm2.530] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Revised: 07/23/2021] [Accepted: 07/26/2021] [Indexed: 02/06/2023] Open
Abstract
Cardiac voltage-gated ion channels (VGICs) play critical roles in mediating cardiac electrophysiological signals, such as action potentials, to maintain normal heart excitability and contraction. Inherited or acquired alterations in the structure, expression, or function of VGICs, as well as VGIC-related side effects of pharmaceutical drug delivery can result in abnormal cellular electrophysiological processes that induce life-threatening cardiac arrhythmias or even sudden cardiac death. Hence, to reduce possible heart-related risks, VGICs must be acknowledged as important targets in drug discovery and safety studies related to cardiac disease. In this review, we first summarize the development and application of electrophysiological techniques that are employed in cardiac VGIC studies alone or in combination with other techniques such as cryoelectron microscopy, optical imaging and optogenetics. Subsequently, we describe the characteristics, structure, mechanisms, and functions of various well-studied VGICs in ventricular myocytes and analyze their roles in and contributions to both physiological cardiac excitability and inherited cardiac diseases. Finally, we address the implications of the structure and function of ventricular VGICs for drug safety evaluation. In summary, multidisciplinary studies on VGICs help researchers discover potential targets of VGICs and novel VGICs in heart, enrich their knowledge of the properties and functions, determine the operation mechanisms of pathological VGICs, and introduce groundbreaking trends in drug therapy strategies, and drug safety evaluation.
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Affiliation(s)
- Lulan Chen
- Department of Cardiology, Shanghai Institute of Cardiovascular DiseasesShanghai Xuhui District Central Hospital & Zhongshan‐xuhui Hospital, Zhongshan Hospital, Fudan UniversityShanghaiChina
| | - Yue He
- Department of CardiologyShanghai Xuhui District Central Hospital & Zhongshan‐xuhui HospitalShanghaiChina
| | - Xiangdong Wang
- Institute of Clinical Science, Zhongshan HospitalFudan UniversityShanghaiChina
| | - Junbo Ge
- Department of Cardiology, Shanghai Institute of Cardiovascular DiseasesShanghai Xuhui District Central Hospital & Zhongshan‐xuhui Hospital, Zhongshan Hospital, Fudan UniversityShanghaiChina
| | - Hua Li
- Department of Cardiology, Shanghai Institute of Cardiovascular DiseasesShanghai Xuhui District Central Hospital & Zhongshan‐xuhui Hospital, Zhongshan Hospital, Fudan UniversityShanghaiChina
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17
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Blandin CE, Gravez BJ, Hatem SN, Balse E. Remodeling of Ion Channel Trafficking and Cardiac Arrhythmias. Cells 2021; 10:cells10092417. [PMID: 34572065 PMCID: PMC8468138 DOI: 10.3390/cells10092417] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Revised: 09/08/2021] [Accepted: 09/11/2021] [Indexed: 01/08/2023] Open
Abstract
Both inherited and acquired cardiac arrhythmias are often associated with the abnormal functional expression of ion channels at the cellular level. The complex machinery that continuously traffics, anchors, organizes, and recycles ion channels at the plasma membrane of a cardiomyocyte appears to be a major source of channel dysfunction during cardiac arrhythmias. This has been well established with the discovery of mutations in the genes encoding several ion channels and ion channel partners during inherited cardiac arrhythmias. Fibrosis, altered myocyte contacts, and post-transcriptional protein changes are common factors that disorganize normal channel trafficking during acquired cardiac arrhythmias. Channel availability, described notably for hERG and KV1.5 channels, could be another potent arrhythmogenic mechanism. From this molecular knowledge on cardiac arrhythmias will emerge novel antiarrhythmic strategies.
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Affiliation(s)
- Camille E. Blandin
- INSERM, Unité de Recherche sur les Maladies Cardiovasculaires, le Métabolisme et la Nutrition—UNITE 1166, Sorbonne Université, EQUIPE 3, F-75013 Paris, France; (C.E.B.); (B.J.G.); (S.N.H.)
| | - Basile J. Gravez
- INSERM, Unité de Recherche sur les Maladies Cardiovasculaires, le Métabolisme et la Nutrition—UNITE 1166, Sorbonne Université, EQUIPE 3, F-75013 Paris, France; (C.E.B.); (B.J.G.); (S.N.H.)
| | - Stéphane N. Hatem
- INSERM, Unité de Recherche sur les Maladies Cardiovasculaires, le Métabolisme et la Nutrition—UNITE 1166, Sorbonne Université, EQUIPE 3, F-75013 Paris, France; (C.E.B.); (B.J.G.); (S.N.H.)
- ICAN—Institute of Cardiometabolism and Nutrition, Institute of Cardiology, Pitié-Salpêtrière Hospital, Sorbonne University, F-75013 Paris, France
| | - Elise Balse
- INSERM, Unité de Recherche sur les Maladies Cardiovasculaires, le Métabolisme et la Nutrition—UNITE 1166, Sorbonne Université, EQUIPE 3, F-75013 Paris, France; (C.E.B.); (B.J.G.); (S.N.H.)
- Correspondence:
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18
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Rivaud MR, Delmar M, Remme CA. Heritable arrhythmia syndromes associated with abnormal cardiac sodium channel function: ionic and non-ionic mechanisms. Cardiovasc Res 2021; 116:1557-1570. [PMID: 32251506 PMCID: PMC7341171 DOI: 10.1093/cvr/cvaa082] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Revised: 03/01/2020] [Accepted: 04/01/2020] [Indexed: 12/19/2022] Open
Abstract
The cardiac sodium channel NaV1.5, encoded by the SCN5A gene, is responsible for the fast upstroke of the action potential. Mutations in SCN5A may cause sodium channel dysfunction by decreasing peak sodium current, which slows conduction and facilitates reentry-based arrhythmias, and by enhancing late sodium current, which prolongs the action potential and sets the stage for early afterdepolarization and arrhythmias. Yet, some NaV1.5-related disorders, in particular structural abnormalities, cannot be directly or solely explained on the basis of defective NaV1.5 expression or biophysics. An emerging concept that may explain the large disease spectrum associated with SCN5A mutations centres around the multifunctionality of the NaV1.5 complex. In this alternative view, alterations in NaV1.5 affect processes that are independent of its canonical ion-conducting role. We here propose a novel classification of NaV1.5 (dys)function, categorized into (i) direct ionic effects of sodium influx through NaV1.5 on membrane potential and consequent action potential generation, (ii) indirect ionic effects of sodium influx on intracellular homeostasis and signalling, and (iii) non-ionic effects of NaV1.5, independent of sodium influx, through interactions with macromolecular complexes within the different microdomains of the cardiomyocyte. These indirect ionic and non-ionic processes may, acting alone or in concert, contribute significantly to arrhythmogenesis. Hence, further exploration of these multifunctional effects of NaV1.5 is essential for the development of novel preventive and therapeutic strategies.
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Affiliation(s)
- Mathilde R Rivaud
- Department of Clinical and Experimental Cardiology, Heart Center, Amsterdam UMC (location AMC), University of Amsterdam, Amsterdam Cardiovascular Sciences, Meigberdreef 15, 1105AZ Amsterdam, The Netherlands
| | - Mario Delmar
- The Leon H. Charney Division of Cardiology, New York University School of Medicine, 435 E 30th St, NSB 707, New York, NY 10016, USA
| | - Carol Ann Remme
- Department of Clinical and Experimental Cardiology, Heart Center, Amsterdam UMC (location AMC), University of Amsterdam, Amsterdam Cardiovascular Sciences, Meigberdreef 15, 1105AZ Amsterdam, The Netherlands
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19
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Ramzan S, Tennstedt S, Tariq M, Khan S, Noor Ul Ayan H, Ali A, Munz M, Thiele H, Korejo AA, Mughal AR, Jamal SZ, Nürnberg P, Baig SM, Erdmann J, Ahmad I. A Novel Missense Mutation in TNNI3K Causes Recessively Inherited Cardiac Conduction Disease in a Consanguineous Pakistani Family. Genes (Basel) 2021; 12:genes12081282. [PMID: 34440456 PMCID: PMC8395014 DOI: 10.3390/genes12081282] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 08/15/2021] [Accepted: 08/16/2021] [Indexed: 11/16/2022] Open
Abstract
Cardiac conduction disease (CCD), which causes altered electrical impulse propagation in the heart, is a life-threatening condition with high morbidity and mortality. It exhibits genetic and clinical heterogeneity with diverse pathomechanisms, but in most cases, it disrupts the synchronous activity of impulse-generating nodes and impulse-conduction underlying the normal heartbeat. In this study, we investigated a consanguineous Pakistani family comprised of four patients with CCD. We applied whole exome sequencing (WES) and co-segregation analysis, which identified a novel homozygous missense mutation (c.1531T>C;(p.Ser511Pro)) in the highly conserved kinase domain of the cardiac troponin I-interacting kinase (TNNI3K) encoding gene. The behaviors of mutant and native TNNI3K were compared by performing all-atom long-term molecular dynamics simulations, which revealed changes at the protein surface and in the hydrogen bond network. Furthermore, intra and intermolecular interaction analyses revealed that p.Ser511Pro causes structural variation in the ATP-binding pocket and the homodimer interface. These findings suggest p.Ser511Pro to be a pathogenic variant. Our study provides insights into how the variant perturbs the TNNI3K structure-function relationship, leading to a disease state. This is the first report of a recessive mutation in TNNI3K and the first mutation in this gene identified in the Pakistani population.
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Affiliation(s)
- Shafaq Ramzan
- Institute for Cardiogenetics, University of Lübeck, 23562 Lübeck, Germany; (S.R.); (S.T.); (H.N.U.A.); (M.M.); (J.E.)
- National Institute for Biotechnology and Genetic Engineering (NIBGE-C), Institute of Engineering and Applied Sciences (PIEAS), Islamabad 44000, Pakistan; (M.T.); (S.K.); (A.A.); (S.M.B.)
| | - Stephanie Tennstedt
- Institute for Cardiogenetics, University of Lübeck, 23562 Lübeck, Germany; (S.R.); (S.T.); (H.N.U.A.); (M.M.); (J.E.)
- DZHK (German Research Centre for Cardiovascular Research) Partner Site Hamburg/Lübeck/Kiel, 23562 Lübeck, Germany
- University Heart Center Lübeck, 23562 Lübeck, Germany
| | - Muhammad Tariq
- National Institute for Biotechnology and Genetic Engineering (NIBGE-C), Institute of Engineering and Applied Sciences (PIEAS), Islamabad 44000, Pakistan; (M.T.); (S.K.); (A.A.); (S.M.B.)
| | - Sheraz Khan
- National Institute for Biotechnology and Genetic Engineering (NIBGE-C), Institute of Engineering and Applied Sciences (PIEAS), Islamabad 44000, Pakistan; (M.T.); (S.K.); (A.A.); (S.M.B.)
| | - Hafiza Noor Ul Ayan
- Institute for Cardiogenetics, University of Lübeck, 23562 Lübeck, Germany; (S.R.); (S.T.); (H.N.U.A.); (M.M.); (J.E.)
- National Institute for Biotechnology and Genetic Engineering (NIBGE-C), Institute of Engineering and Applied Sciences (PIEAS), Islamabad 44000, Pakistan; (M.T.); (S.K.); (A.A.); (S.M.B.)
| | - Aamir Ali
- National Institute for Biotechnology and Genetic Engineering (NIBGE-C), Institute of Engineering and Applied Sciences (PIEAS), Islamabad 44000, Pakistan; (M.T.); (S.K.); (A.A.); (S.M.B.)
| | - Matthias Munz
- Institute for Cardiogenetics, University of Lübeck, 23562 Lübeck, Germany; (S.R.); (S.T.); (H.N.U.A.); (M.M.); (J.E.)
- DZHK (German Research Centre for Cardiovascular Research) Partner Site Hamburg/Lübeck/Kiel, 23562 Lübeck, Germany
| | - Holger Thiele
- Cologne Center for Genomics (CCG), University of Cologne, Faculty of Medicine, University Hospital Cologne, 50931 Cologne, Germany; (H.T.); (P.N.)
| | - Asad Aslam Korejo
- National Institute of Cardiovascular Disease, Karachi 75510, Pakistan; (A.A.K.); (S.Z.J.)
| | | | - Syed Zahid Jamal
- National Institute of Cardiovascular Disease, Karachi 75510, Pakistan; (A.A.K.); (S.Z.J.)
| | - Peter Nürnberg
- Cologne Center for Genomics (CCG), University of Cologne, Faculty of Medicine, University Hospital Cologne, 50931 Cologne, Germany; (H.T.); (P.N.)
- Center for Molecular Medicine Cologne (CMMC), University of Cologne, Faculty of Medicine, University Hospital Cologne, 50931 Cologne, Germany
| | - Shahid Mahmood Baig
- National Institute for Biotechnology and Genetic Engineering (NIBGE-C), Institute of Engineering and Applied Sciences (PIEAS), Islamabad 44000, Pakistan; (M.T.); (S.K.); (A.A.); (S.M.B.)
- Department of Biological and Biomedical Sciences, Aga Khan University, Karachi 74000, Pakistan
- Pakistan Science Foundation (PSF), 1-Constitution Avenue, G-5/2, Islamabad 44000, Pakistan
| | - Jeanette Erdmann
- Institute for Cardiogenetics, University of Lübeck, 23562 Lübeck, Germany; (S.R.); (S.T.); (H.N.U.A.); (M.M.); (J.E.)
- DZHK (German Research Centre for Cardiovascular Research) Partner Site Hamburg/Lübeck/Kiel, 23562 Lübeck, Germany
- University Heart Center Lübeck, 23562 Lübeck, Germany
| | - Ilyas Ahmad
- Institute for Cardiogenetics, University of Lübeck, 23562 Lübeck, Germany; (S.R.); (S.T.); (H.N.U.A.); (M.M.); (J.E.)
- DZHK (German Research Centre for Cardiovascular Research) Partner Site Hamburg/Lübeck/Kiel, 23562 Lübeck, Germany
- University Heart Center Lübeck, 23562 Lübeck, Germany
- Correspondence: ; Tel.: +49-(0)451-3101-8320
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20
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Ezekian JE, Rehder C, Kishnani PS, Landstrom AP. Interpretation of Incidental Genetic Findings Localizing to Genes Associated With Cardiac Channelopathies and Cardiomyopathies. CIRCULATION-GENOMIC AND PRECISION MEDICINE 2021; 14:e003200. [PMID: 34384235 DOI: 10.1161/circgen.120.003200] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Recent advances in next-genetic sequencing technology have facilitated an expansion in the use of exome and genome sequencing in the research and clinical settings. While this has aided in the genetic diagnosis of individuals with atypical clinical presentations, there has been a marked increase in the number of incidentally identified variants of uncertain diagnostic significance in genes identified as clinically actionable by the American College of Medical Genetics guidelines. Approximately 20 of these genes are associated with cardiac diseases, which carry a significant risk of sudden cardiac death. While identification of at-risk individuals is paramount, increased discovery of incidental variants of uncertain diagnostic significance has placed a burden on the clinician tasked with determining the diagnostic significance of these findings. Herein, we describe the scope of this emerging problem using cardiovascular genetics to illustrate the challenges associated with variants of uncertain diagnostic significance interpretation. We review the evidence for diagnostic weight of these variants, discuss the role of clinical genetics providers in patient care, and put forward general recommendations about the interpretation of incidentally identified variants found with clinical genetic testing.
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Affiliation(s)
- Jordan E Ezekian
- Division of Cardiology, Department of Pediatrics (J.E.E., A.P.L.), Duke University School of Medicine, Durham, NC
| | - Catherine Rehder
- Department of Pathology (C.R.), Duke University School of Medicine, Durham, NC
| | - Priya S Kishnani
- Division of Medical Genetics, Department of Pediatrics (P.S.K.), Duke University School of Medicine, Durham, NC
| | - Andrew P Landstrom
- Division of Cardiology, Department of Pediatrics (J.E.E., A.P.L.), Duke University School of Medicine, Durham, NC.,Department of Cell Biology (A.P.L.), Duke University School of Medicine, Durham, NC
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21
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Adedeji OM, Falk Z, Tracy CM, Batarseh A. Brugada pattern in an afebrile patient with acute COVID-19. BMJ Case Rep 2021; 14:e242632. [PMID: 34257116 PMCID: PMC8278894 DOI: 10.1136/bcr-2021-242632] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/20/2021] [Indexed: 11/24/2022] Open
Abstract
COVID-19 has been associated with significant risk for cardiac arrhythmias, particularly in patients with underlying cardiac conditions or prior histories of arrhythmia. It has been shown that a Brugada pattern can be unmasked in febrile patients with COVID-19. Herein we report a unique case of an afebrile patient without known prior history of Brugada presenting with Brugada pattern on ECG.
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Affiliation(s)
- Omowunmi M Adedeji
- Internal Medicine, The George Washington University Hospital, Washington, DC, USA
| | - Zachary Falk
- Internal Medicine, The George Washington University Hospital, Washington, DC, USA
| | - Cynthia M Tracy
- Cardiology, The George Washington University Hospital, Washington, DC, USA
| | - Alberto Batarseh
- Internal Medicine, The George Washington University Hospital, Washington, DC, USA
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22
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Nakajima T, Tamura S, Kurabayashi M, Kaneko Y. Towards Mutation-Specific Precision Medicine in Atypical Clinical Phenotypes of Inherited Arrhythmia Syndromes. Int J Mol Sci 2021; 22:ijms22083930. [PMID: 33920294 PMCID: PMC8069124 DOI: 10.3390/ijms22083930] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Accepted: 04/08/2021] [Indexed: 12/19/2022] Open
Abstract
Most causal genes for inherited arrhythmia syndromes (IASs) encode cardiac ion channel-related proteins. Genotype-phenotype studies and functional analyses of mutant genes, using heterologous expression systems and animal models, have revealed the pathophysiology of IASs and enabled, in part, the establishment of causal gene-specific precision medicine. Additionally, the utilization of induced pluripotent stem cell (iPSC) technology have provided further insights into the pathophysiology of IASs and novel promising therapeutic strategies, especially in long QT syndrome. It is now known that there are atypical clinical phenotypes of IASs associated with specific mutations that have unique electrophysiological properties, which raises a possibility of mutation-specific precision medicine. In particular, patients with Brugada syndrome harboring an SCN5A R1632C mutation exhibit exercise-induced cardiac events, which may be caused by a marked activity-dependent loss of R1632C-Nav1.5 availability due to a marked delay of recovery from inactivation. This suggests that the use of isoproterenol should be avoided. Conversely, the efficacy of β-blocker needs to be examined. Patients harboring a KCND3 V392I mutation exhibit both cardiac (early repolarization syndrome and paroxysmal atrial fibrillation) and cerebral (epilepsy) phenotypes, which may be associated with a unique mixed electrophysiological property of V392I-Kv4.3. Since the epileptic phenotype appears to manifest prior to cardiac events in this mutation carrier, identifying KCND3 mutations in patients with epilepsy and providing optimal therapy will help prevent sudden unexpected death in epilepsy. Further studies using the iPSC technology may provide novel insights into the pathophysiology of atypical clinical phenotypes of IASs and the development of mutation-specific precision medicine.
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23
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Tambi R, Abdel Hameid R, Bankapur A, Nassir N, Begum G, Alsheikh-Ali A, Uddin M, Berdiev BK. Single-cell transcriptomics trajectory and molecular convergence of clinically relevant mutations in Brugada syndrome. Am J Physiol Heart Circ Physiol 2021; 320:H1935-H1948. [PMID: 33797273 DOI: 10.1152/ajpheart.00061.2021] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Brugada syndrome (BrS) is a rare, inherited arrhythmia with high risk of sudden cardiac death. To evaluate the molecular convergence of clinically relevant mutations and to identify developmental cardiac cell types that are associated with BrS etiology, we collected 733 mutations represented by 16 sodium, calcium, potassium channels, and regulatory and structural genes related to BrS. Among the clinically relevant mutations, 266 are unique singletons and 88 mutations are recurrent. We observed an over-representation of clinically relevant mutations (∼80%) in SCN5A gene and also identified several candidate genes, including GPD1L, TRPM4, and SCN10A. Furthermore, protein domain enrichment analysis revealed that a large proportion of the mutations impacted ion transport domains in multiple genes, including SCN5A, TRPM4, and SCN10A. A comparative protein domain analysis of SCN5A further established a significant (P = 0.04) enrichment of clinically relevant mutations within ion transport domain, including a significant (P = 0.02) mutation hotspot within 1321-1380 residue. The enrichment of clinically relevant mutations within SCN5A ion transport domain is stronger (P = 0.00003) among early onset of BrS. Our spatiotemporal cellular heart developmental (prenatal to adult) trajectory analysis applying single-cell transcriptome identified the most frequently BrS-mutated genes (SCN5A and GPD1L) are significantly upregulated in the prenatal cardiomyocytes. A more restrictive cellular expression trajectory is prominent in the adult heart ventricular cardiomyocytes compared to prenatal. Our study suggests that genomic and proteomic hotspots in BrS converge into ion transport pathway and cardiomyocyte as a major BrS-associated cell type that provides insight into the complex genetic etiology of BrS.NEW & NOTEWORTHY Brugada syndrome is a rare inherited arrhythmia with high risk of sudden cardiac death. We present the findings for a molecular convergence of clinically relevant mutations and identification of a single-cell transcriptome-derived cardiac cell types that are associated with the etiology of BrS. Our study suggests that genomic and proteomic hotspots in BrS converge into ion transport pathway and cardiomyocyte as a major BrS-associated cell type that provides insight into the complex genetic etiology of BrS.
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Affiliation(s)
- Richa Tambi
- Mohammed Bin Rashid University of Medicine and Health Sciences, Dubai, United Arab Emirates
| | - Reem Abdel Hameid
- Mohammed Bin Rashid University of Medicine and Health Sciences, Dubai, United Arab Emirates
| | - Asma Bankapur
- Mohammed Bin Rashid University of Medicine and Health Sciences, Dubai, United Arab Emirates
| | - Nasna Nassir
- Mohammed Bin Rashid University of Medicine and Health Sciences, Dubai, United Arab Emirates
| | - Ghausia Begum
- Mohammed Bin Rashid University of Medicine and Health Sciences, Dubai, United Arab Emirates
| | - Alawi Alsheikh-Ali
- Mohammed Bin Rashid University of Medicine and Health Sciences, Dubai, United Arab Emirates
| | - Mohammed Uddin
- Mohammed Bin Rashid University of Medicine and Health Sciences, Dubai, United Arab Emirates
| | - Bakhrom K Berdiev
- Mohammed Bin Rashid University of Medicine and Health Sciences, Dubai, United Arab Emirates
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24
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Ademuwagun IA, Rotimi SO, Syrbe S, Ajamma YU, Adebiyi E. Voltage Gated Sodium Channel Genes in Epilepsy: Mutations, Functional Studies, and Treatment Dimensions. Front Neurol 2021; 12:600050. [PMID: 33841294 PMCID: PMC8024648 DOI: 10.3389/fneur.2021.600050] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Accepted: 03/01/2021] [Indexed: 12/19/2022] Open
Abstract
Genetic epilepsy occurs as a result of mutations in either a single gene or an interplay of different genes. These mutations have been detected in ion channel and non-ion channel genes. A noteworthy class of ion channel genes are the voltage gated sodium channels (VGSCs) that play key roles in the depolarization phase of action potentials in neurons. Of huge significance are SCN1A, SCN1B, SCN2A, SCN3A, and SCN8A genes that are highly expressed in the brain. Genomic studies have revealed inherited and de novo mutations in sodium channels that are linked to different forms of epilepsies. Due to the high frequency of sodium channel mutations in epilepsy, this review discusses the pathogenic mutations in the sodium channel genes that lead to epilepsy. In addition, it explores the functional studies on some known mutations and the clinical significance of VGSC mutations in the medical management of epilepsy. The understanding of these channel mutations may serve as a strong guide in making effective treatment decisions in patient management.
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Affiliation(s)
- Ibitayo Abigail Ademuwagun
- Covenant University Bioinformatics Research, Covenant University, Ota, Nigeria
- Department of Biochemistry, Covenant University, Ota, Nigeria
| | - Solomon Oladapo Rotimi
- Covenant University Bioinformatics Research, Covenant University, Ota, Nigeria
- Department of Biochemistry, Covenant University, Ota, Nigeria
| | - Steffen Syrbe
- Clinic for Pediatric and Adolescent Medicine, Heidelberg University, Heidelberg, Germany
| | | | - Ezekiel Adebiyi
- Covenant University Bioinformatics Research, Covenant University, Ota, Nigeria
- Department of Computer and Information Sciences, Covenant University, Ota, Nigeria
- Division of Applied Bioinformatics, German Cancer Research Center (DKFZ), Heidelberg, Germany
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25
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Yoon N, Jeong HK, Lee KH, Park HW, Cho JG. Right Ventricular Longitudinal Conduction Delay in Patients with Brugada Syndrome. J Korean Med Sci 2021; 36:e75. [PMID: 33754508 PMCID: PMC7985285 DOI: 10.3346/jkms.2021.36.e75] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/15/2020] [Accepted: 01/12/2021] [Indexed: 11/20/2022] Open
Abstract
BACKGROUND The mechanism of Brugada syndrome (BrS) is still unclear, with different researchers favoring either the repolarization or depolarization hypothesis. Prolonged longitudinal activation time has been verified in only a small number of human right ventricles (RVs). The purpose of the present study was to demonstrate RV conduction delays in BrS. METHODS The RV outflow tract (RVOT)-to-RV apex (RVA) and RVA-to-RVOT conduction times were measured by endocardial stimulation and mapping in 7 patients with BrS and 14 controls. RESULTS Patients with BrS had a longer PR interval (180 ± 12.6 vs. 142 ± 6.7 ms, P = 0.016). The RVA-to-RVOT conduction time was longer in the patients with BrS than in controls (stimulation at 600 ms, 107 ± 9.9 vs. 73 ± 3.4 ms, P = 0.001; stimulation at 500 ms, 104 ± 12.3 vs. 74 ± 4.2 ms, P = 0.037; stimulation at 400 ms, 107 ±12.2 vs. 73 ± 5.1 ms, P = 0.014). The RVOT-to-RVA conduction time was longer in the patients with BrS than in controls (stimulation at 500 ms, 95 ± 10.3 vs. 62 ± 4.1 ms, P = 0.007; stimulation at 400 ms, 94 ±11.2 vs. 64 ± 4.6 ms, P = 0.027). The difference in longitudinal conduction time was not significant when isoproterenol was administered. CONCLUSION The patients with BrS showed an RV longitudinal conduction delay obviously. These findings suggest that RV conduction delay might contribute to generate the BrS phenotype.
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Affiliation(s)
- Namsik Yoon
- Heart Center of Chonnam National University Hospital, Gwangju, Korea
- Division of Cardiology, Department of Internal Medicine, Chonnam National University Medical School, Gwangju, Korea
| | - Hyung Ki Jeong
- Heart Center of Chonnam National University Hospital, Gwangju, Korea
| | - Ki Hong Lee
- Heart Center of Chonnam National University Hospital, Gwangju, Korea
- Division of Cardiology, Department of Internal Medicine, Chonnam National University Medical School, Gwangju, Korea
| | - Hyung Wook Park
- Heart Center of Chonnam National University Hospital, Gwangju, Korea
- Division of Cardiology, Department of Internal Medicine, Chonnam National University Medical School, Gwangju, Korea
| | - Jeong Gwan Cho
- Heart Center of Chonnam National University Hospital, Gwangju, Korea
- Division of Cardiology, Department of Internal Medicine, Chonnam National University Medical School, Gwangju, Korea.
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26
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Bouza AA, Edokobi N, Hodges SL, Pinsky AM, Offord J, Piao L, Zhao YT, Lopatin AN, Lopez-Santiago LF, Isom LL. Sodium channel β1 subunits participate in regulated intramembrane proteolysis-excitation coupling. JCI Insight 2021; 6:141776. [PMID: 33411695 PMCID: PMC7934843 DOI: 10.1172/jci.insight.141776] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Accepted: 12/29/2020] [Indexed: 12/17/2022] Open
Abstract
Loss-of-function (LOF) variants in SCN1B, encoding voltage-gated sodium channel β1 subunits, are linked to human diseases with high risk of sudden death, including developmental and epileptic encephalopathy and cardiac arrhythmia. β1 Subunits modulate the cell-surface localization, gating, and kinetics of sodium channel pore-forming α subunits. They also participate in cell-cell and cell-matrix adhesion, resulting in intracellular signal transduction, promotion of cell migration, calcium handling, and regulation of cell morphology. Here, we investigated regulated intramembrane proteolysis (RIP) of β1 by BACE1 and γ-secretase and show that β1 subunits are substrates for sequential RIP by BACE1 and γ-secretase, resulting in the generation of a soluble intracellular domain (ICD) that is translocated to the nucleus. Using RNA sequencing, we identified a subset of genes that are downregulated by β1-ICD overexpression in heterologous cells but upregulated in Scn1b-null cardiac tissue, which lacks β1-ICD signaling, suggesting that the β1-ICD may normally function as a molecular brake on gene transcription in vivo. We propose that human disease variants resulting in SCN1B LOF cause transcriptional dysregulation that contributes to altered excitability. Moreover, these results provide important insights into the mechanism of SCN1B-linked channelopathies, adding RIP-excitation coupling to the multifunctionality of sodium channel β1 subunits.
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Affiliation(s)
- Alexandra A Bouza
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Nnamdi Edokobi
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Samantha L Hodges
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Alexa M Pinsky
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - James Offord
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Lin Piao
- Department of Molecular & Integrative Physiology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Yan-Ting Zhao
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Anatoli N Lopatin
- Department of Molecular & Integrative Physiology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Luis F Lopez-Santiago
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Lori L Isom
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, Michigan, USA.,Department of Molecular & Integrative Physiology, University of Michigan Medical School, Ann Arbor, Michigan, USA.,Department of Neurology, University of Michigan Medical School, Ann Arbor, Michigan, USA
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27
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Martinez-Moreno R, Selga E, Riuró H, Carreras D, Parnes M, Srinivasan C, Wangler MF, Pérez GJ, Scornik FS, Brugada R. An SCN1B Variant Affects Both Cardiac-Type (Na V1.5) and Brain-Type (Na V1.1) Sodium Currents and Contributes to Complex Concomitant Brain and Cardiac Disorders. Front Cell Dev Biol 2020; 8:528742. [PMID: 33134290 PMCID: PMC7550680 DOI: 10.3389/fcell.2020.528742] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Accepted: 08/21/2020] [Indexed: 12/19/2022] Open
Abstract
Voltage-gated sodium (NaV) channels are transmembrane proteins that initiate and propagate neuronal and cardiac action potentials. NaV channel β subunits have been widely studied due to their modulatory role. Mice null for Scn1b, which encodes NaV β1 and β1b subunits, have defects in neuronal development and excitability, spontaneous generalized seizures, cardiac arrhythmias, and early mortality. A mutation in exon 3 of SCN1B, c.308A>T leading to β1_p.D103V and β1b_p.D103V, was previously found in a patient with a history of proarrhythmic conditions with progressive atrial standstill as well as cognitive and motor deficits accompanying structural brain abnormalities. We investigated whether β1 or β1b subunits carrying this mutation affect NaV1.5 and/or NaV1.1 currents using a whole cell patch-clamp technique in tsA201 cells. We observed a decrease in sodium current density in cells co-expressing NaV1.5 or NaV1.1 and β1D103V compared to β1WT. Interestingly, β1bD103V did not affect NaV1.1 sodium current density but induced a positive shift in the voltage dependence of inactivation and a faster recovery from inactivation compared to β1bWT. The β1bD103V isoform did not affect NaV1.5 current properties. Although the SCN1B_c.308A>T mutation may not be the sole cause of the patient's symptoms, we observed a clear loss of function in both cardiac and brain sodium channels. Our results suggest that the mutant β1 and β1b subunits play a fundamental role in the observed electrical dysfunction.
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Affiliation(s)
- Rebecca Martinez-Moreno
- Departament de Ciències Mèdiques, Facultat de Medicina, Universitat de Girona, Girona, Spain
- Cardiovascular Genetics Center, Institut d’Investigació Biomèdica de Girona Dr. Josep Trueta, Girona, Spain
| | - Elisabet Selga
- Departament de Ciències Mèdiques, Facultat de Medicina, Universitat de Girona, Girona, Spain
- Cardiovascular Genetics Center, Institut d’Investigació Biomèdica de Girona Dr. Josep Trueta, Girona, Spain
- Faculty of Medicine, University of Vic-Central University of Catalonia (UVic-UCC), Vic, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Cardiovasculares (CIBERCV)Madrid, Spain
| | - Helena Riuró
- Cardiovascular Genetics Center, Institut d’Investigació Biomèdica de Girona Dr. Josep Trueta, Girona, Spain
| | - David Carreras
- Cardiovascular Genetics Center, Institut d’Investigació Biomèdica de Girona Dr. Josep Trueta, Girona, Spain
| | - Mered Parnes
- Blue Bird Circle Clinic for Pediatric Neurology, Section, of Pediatric Neurology and Developmental Neuroscience, Texas Children’s Hospital, Baylor College of Medicine, Houston, TX, United States
| | - Chandra Srinivasan
- Section of Pediatric Cardiac Electrophysiology, Division of Pediatric Cardiology, Department of Pediatrics, University of Texas Health Science Center at Houston, Houston, TX, United States
| | - Michael F. Wangler
- Texas Children’s Hospital, Houston, TX, United States
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, United States
| | - Guillermo J. Pérez
- Departament de Ciències Mèdiques, Facultat de Medicina, Universitat de Girona, Girona, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Cardiovasculares (CIBERCV)Madrid, Spain
| | - Fabiana S. Scornik
- Departament de Ciències Mèdiques, Facultat de Medicina, Universitat de Girona, Girona, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Cardiovasculares (CIBERCV)Madrid, Spain
| | - Ramon Brugada
- Departament de Ciències Mèdiques, Facultat de Medicina, Universitat de Girona, Girona, Spain
- Cardiovascular Genetics Center, Institut d’Investigació Biomèdica de Girona Dr. Josep Trueta, Girona, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Cardiovasculares (CIBERCV)Madrid, Spain
- Hospital Josep Trueta, Girona, Spain
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28
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Llongueras JP, Das S, De Waele J, Capulzini L, Sorgente A, Van Petegem F, Bosmans F. Biophysical Investigation of Sodium Channel Interaction with β-Subunit Variants Associated with Arrhythmias. Bioelectricity 2020; 2:269-278. [PMID: 34476357 DOI: 10.1089/bioe.2020.0030] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Background: Voltage-gated sodium (NaV) channels help regulate electrical activity of the plasma membrane. Mutations in associated subunits can result in pathological outcomes. Here we examined the interaction of NaV channels with cardiac arrhythmia-linked mutations in SCN2B and SCN4B, two genes that encode auxiliary β-subunits. Materials and Methods: To investigate changes in SCN2B R137H and SCN4B I80T function, we combined three-dimensional X-ray crystallography with electrophysiological measurements on NaV1.5, the dominant subtype in the heart. Results: SCN4B I80T alters channel activity, whereas SCN2B R137H does not have an apparent effect. Structurally, the SCN4B I80T perturbation alters hydrophobic packing of the subunit with major structural changes and causes a thermal destabilization of the folding. In contrast, SCN2B R137H leads to structural changes but overall protein stability is unaffected. Conclusion: SCN4B I80T data suggest a functionally important region in the interaction between NaV1.5 and β4 that, when disrupted, could lead to channel dysfunction. A lack of apparent functional effects of SCN2B R137H on NaV1.5 suggests an alternative working mechanism, possibly through other NaV channel subtypes present in heart tissue. Indeed, mapping the structural variations of SCN2B R137H onto neuronal NaV channel structures suggests altered interaction patterns.
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Affiliation(s)
- José P Llongueras
- Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Samir Das
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, Canada.,Life Sciences Institute, University of British Columbia, Vancouver, Canada
| | - Jolien De Waele
- Department of Basic and Applied Medical Sciences, Ghent University, Ghent, Belgium
| | - Lucio Capulzini
- Arrhythmia and Electrophysiology Center, Department of Cardiology, Epicura Hospitalier Center, Hornu, Belgium
| | - Antonio Sorgente
- Arrhythmia and Electrophysiology Center, Department of Cardiology, Epicura Hospitalier Center, Hornu, Belgium
| | - Filip Van Petegem
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, Canada.,Life Sciences Institute, University of British Columbia, Vancouver, Canada
| | - Frank Bosmans
- Department of Basic and Applied Medical Sciences, Ghent University, Ghent, Belgium
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29
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Bouza AA, Philippe JM, Edokobi N, Pinsky AM, Offord J, Calhoun JD, Lopez-Florán M, Lopez-Santiago LF, Jenkins PM, Isom LL. Sodium channel β1 subunits are post-translationally modified by tyrosine phosphorylation, S-palmitoylation, and regulated intramembrane proteolysis. J Biol Chem 2020; 295:10380-10393. [PMID: 32503841 PMCID: PMC7383382 DOI: 10.1074/jbc.ra120.013978] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Revised: 06/02/2020] [Indexed: 01/05/2023] Open
Abstract
Voltage-gated sodium channel (VGSC) β1 subunits are multifunctional proteins that modulate the biophysical properties and cell-surface localization of VGSC α subunits and participate in cell-cell and cell-matrix adhesion, all with important implications for intracellular signal transduction, cell migration, and differentiation. Human loss-of-function variants in SCN1B, the gene encoding the VGSC β1 subunits, are linked to severe diseases with high risk for sudden death, including epileptic encephalopathy and cardiac arrhythmia. We showed previously that β1 subunits are post-translationally modified by tyrosine phosphorylation. We also showed that β1 subunits undergo regulated intramembrane proteolysis via the activity of β-secretase 1 and γ-secretase, resulting in the generation of a soluble intracellular domain, β1-ICD, which modulates transcription. Here, we report that β1 subunits are phosphorylated by FYN kinase. Moreover, we show that β1 subunits are S-palmitoylated. Substitution of a single residue in β1, Cys-162, to alanine prevented palmitoylation, reduced the level of β1 polypeptides at the plasma membrane, and reduced the extent of β1-regulated intramembrane proteolysis, suggesting that the plasma membrane is the site of β1 proteolytic processing. Treatment with the clathrin-mediated endocytosis inhibitor, Dyngo-4a, re-stored the plasma membrane association of β1-p.C162A to WT levels. Despite these observations, palmitoylation-null β1-p.C162A modulated sodium current and sorted to detergent-resistant membrane fractions normally. This is the first demonstration of S-palmitoylation of a VGSC β subunit, establishing precedence for this post-translational modification as a regulatory mechanism in this protein family.
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Affiliation(s)
- Alexandra A Bouza
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Julie M Philippe
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Nnamdi Edokobi
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Alexa M Pinsky
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - James Offord
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Jeffrey D Calhoun
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Mariana Lopez-Florán
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Luis F Lopez-Santiago
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Paul M Jenkins
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, Michigan, USA
- Department of Psychiatry, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Lori L Isom
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, Michigan, USA
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, Michigan, USA
- Department of Neurology, University of Michigan Medical School, Ann Arbor, Michigan, USA
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30
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Salvage SC, Huang CLH, Jackson AP. Cell-Adhesion Properties of β-Subunits in the Regulation of Cardiomyocyte Sodium Channels. Biomolecules 2020; 10:biom10070989. [PMID: 32630316 PMCID: PMC7407995 DOI: 10.3390/biom10070989] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2020] [Revised: 06/25/2020] [Accepted: 06/27/2020] [Indexed: 12/17/2022] Open
Abstract
Voltage-gated sodium (Nav) channels drive the rising phase of the action potential, essential for electrical signalling in nerves and muscles. The Nav channel α-subunit contains the ion-selective pore. In the cardiomyocyte, Nav1.5 is the main Nav channel α-subunit isoform, with a smaller expression of neuronal Nav channels. Four distinct regulatory β-subunits (β1–4) bind to the Nav channel α-subunits. Previous work has emphasised the β-subunits as direct Nav channel gating modulators. However, there is now increasing appreciation of additional roles played by these subunits. In this review, we focus on β-subunits as homophilic and heterophilic cell-adhesion molecules and the implications for cardiomyocyte function. Based on recent cryogenic electron microscopy (cryo-EM) data, we suggest that the β-subunits interact with Nav1.5 in a different way from their binding to other Nav channel isoforms. We believe this feature may facilitate trans-cell-adhesion between β1-associated Nav1.5 subunits on the intercalated disc and promote ephaptic conduction between cardiomyocytes.
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Affiliation(s)
- Samantha C. Salvage
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, UK;
- Correspondence: (S.C.S.); (A.P.J.); Tel.: +44-1223-765950 (S.C.S.); +44-1223-765951 (A.P.J.)
| | - Christopher L.-H. Huang
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, UK;
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3EG, UK
| | - Antony P. Jackson
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, UK;
- Correspondence: (S.C.S.); (A.P.J.); Tel.: +44-1223-765950 (S.C.S.); +44-1223-765951 (A.P.J.)
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31
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Brewer KR, Kuenze G, Vanoye CG, George AL, Meiler J, Sanders CR. Structures Illuminate Cardiac Ion Channel Functions in Health and in Long QT Syndrome. Front Pharmacol 2020; 11:550. [PMID: 32431610 PMCID: PMC7212895 DOI: 10.3389/fphar.2020.00550] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Accepted: 04/09/2020] [Indexed: 12/13/2022] Open
Abstract
The cardiac action potential is critical to the production of a synchronized heartbeat. This electrical impulse is governed by the intricate activity of cardiac ion channels, among them the cardiac voltage-gated potassium (Kv) channels KCNQ1 and hERG as well as the voltage-gated sodium (Nav) channel encoded by SCN5A. Each channel performs a highly distinct function, despite sharing a common topology and structural components. These three channels are also the primary proteins mutated in congenital long QT syndrome (LQTS), a genetic condition that predisposes to cardiac arrhythmia and sudden cardiac death due to impaired repolarization of the action potential and has a particular proclivity for reentrant ventricular arrhythmias. Recent cryo-electron microscopy structures of human KCNQ1 and hERG, along with the rat homolog of SCN5A and other mammalian sodium channels, provide atomic-level insight into the structure and function of these proteins that advance our understanding of their distinct functions in the cardiac action potential, as well as the molecular basis of LQTS. In this review, the gating, regulation, LQTS mechanisms, and pharmacological properties of KCNQ1, hERG, and SCN5A are discussed in light of these recent structural findings.
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Affiliation(s)
- Kathryn R. Brewer
- Center for Structural Biology, Vanderbilt University School of Medicine Basic Sciences, Nashville, TN, United States
- Department of Biochemistry, Vanderbilt University, Nashville, TN, United States
| | - Georg Kuenze
- Center for Structural Biology, Vanderbilt University School of Medicine Basic Sciences, Nashville, TN, United States
- Department of Chemistry, Vanderbilt University, Nashville, TN, United States
| | - Carlos G. Vanoye
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
| | - Alfred L. George
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
| | - Jens Meiler
- Center for Structural Biology, Vanderbilt University School of Medicine Basic Sciences, Nashville, TN, United States
- Department of Chemistry, Vanderbilt University, Nashville, TN, United States
- Department of Pharmacology, Vanderbilt University School of Medicine Basic Sciences, Nashville, TN, United States
- Institute for Drug Discovery, Leipzig University Medical School, Leipzig, Germany
| | - Charles R. Sanders
- Center for Structural Biology, Vanderbilt University School of Medicine Basic Sciences, Nashville, TN, United States
- Department of Biochemistry, Vanderbilt University, Nashville, TN, United States
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32
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CYP2J2 Modulates Diverse Transcriptional Programs in Adult Human Cardiomyocytes. Sci Rep 2020; 10:5329. [PMID: 32210298 PMCID: PMC7093536 DOI: 10.1038/s41598-020-62174-w] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Accepted: 03/06/2020] [Indexed: 01/05/2023] Open
Abstract
CYP2J2, a member of the Cytochrome P450 family of enzymes, is the most abundant epoxygenase in the heart and has multifunctional properties including bioactivation of arachidonic acid to epoxyeicosatrienoic acids, which, in turn, have been implicated in mediating several cardiovascular conditions. Using a proteomic approach, we found that CYP2J2 expression is lower in cardiac tissue from patients with cardiomyopathy compared to controls. In order to better elucidate the complex role played by CYP2J2 in cardiac cells, we performed targeted silencing of CYP2J2 expression in human adult ventricular cardiomyocytes and interrogated whole genome transcriptional responses. We found that knockdown of CYP2J2 elicits widespread alterations in gene expression of ventricular cardiomyocytes and leads to the activation of a diverse repertoire of programs, including those involved in ion channel signaling, development, extracellular matrix, and metabolism. Several members of the differentially up-regulated ion channel module have well-known pathogenetic roles in cardiac dysrhythmias. By leveraging causal network and upstream regulator analysis, we identified several candidate drivers of the observed transcriptional response to CYP2J2 silencing; these master regulators have been implicated in aberrant cardiac remodeling, heart failure, and myocyte injury and repair. Collectively, our study demonstrates that CYP2J2 plays a central and multifaceted role in cardiomyocyte homeostasis and provides a framework for identifying critical regulators and pathways influenced by this gene in cardiovascular health and disease.
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33
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Glass WG, Duncan AL, Biggin PC. Computational Investigation of Voltage-Gated Sodium Channel β3 Subunit Dynamics. Front Mol Biosci 2020; 7:40. [PMID: 32266288 PMCID: PMC7103644 DOI: 10.3389/fmolb.2020.00040] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Accepted: 02/19/2020] [Indexed: 01/23/2023] Open
Abstract
Voltage-gated sodium (Na v ) channels form the basis for the initiation of the action potential in excitable cells by allowing sodium ions to pass through the cell membrane. The Na v channel α subunit is known to function both with and without associated β subunits. There is increasing evidence that these β subunits have multiple roles that include not only influencing the voltage-dependent gating but also the ability to alter the spatial distribution of the pore-forming α subunit. Recent structural data has shown possible ways in which β1 subunits may interact with the α subunit. However, the position of the β1 subunit would not be compatible with a previous trimer structure of the β3 subunit. Furthermore, little is currently known about the dynamic behavior of the β subunits both as individual monomers and as higher order oligomers. Here, we use multiscale molecular dynamics simulations to assess the dynamics of the β3, and the closely related, β1 subunit. These findings reveal the spatio-temporal dynamics of β subunits and should provide a useful framework for interpreting future low-resolution experiments such as atomic force microscopy.
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Affiliation(s)
| | | | - Philip C. Biggin
- Structural Bioinformatics and Computational Biochemistry, Department of Biochemistry, University of Oxford, Oxford, United Kingdom
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34
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Monasky MM, Micaglio E, Ciconte G, Pappone C. Brugada Syndrome: Oligogenic or Mendelian Disease? Int J Mol Sci 2020; 21:ijms21051687. [PMID: 32121523 PMCID: PMC7084676 DOI: 10.3390/ijms21051687] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Revised: 02/27/2020] [Accepted: 02/28/2020] [Indexed: 02/06/2023] Open
Abstract
Brugada syndrome (BrS) is diagnosed by a coved-type ST-segment elevation in the right precordial leads on the electrocardiogram (ECG), and it is associated with an increased risk of sudden cardiac death (SCD) compared to the general population. Although BrS is considered a genetic disease, its molecular mechanism remains elusive in about 70-85% of clinically-confirmed cases. Variants occurring in at least 26 different genes have been previously considered causative, although the causative effect of all but the SCN5A gene has been recently challenged, due to the lack of systematic, evidence-based evaluations, such as a variant's frequency among the general population, family segregation analyses, and functional studies. Also, variants within a particular gene can be associated with an array of different phenotypes, even within the same family, preventing a clear genotype-phenotype correlation. Moreover, an emerging concept is that a single mutation may not be enough to cause the BrS phenotype, due to the increasing number of common variants now thought to be clinically relevant. Thus, not only the complete list of genes causative of the BrS phenotype remains to be determined, but also the interplay between rare and common multiple variants. This is particularly true for some common polymorphisms whose roles have been recently re-evaluated by outstanding works, including considering for the first time ever a polygenic risk score derived from the heterozygous state for both common and rare variants. The more common a certain variant is, the less impact this variant might have on heart function. We are aware that further studies are warranted to validate a polygenic risk score, because there is no mutated gene that connects all, or even a majority, of BrS cases. For the same reason, it is currently impossible to create animal and cell line genetic models that represent all BrS cases, which would enable the expansion of studies of this syndrome. Thus, the best model at this point is the human patient population. Further studies should first aim to uncover genetic variants within individuals, as well as to collect family segregation data to identify potential genetic causes of BrS.
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Affiliation(s)
| | | | | | - Carlo Pappone
- Correspondence: ; Tel.: +39-0252-774260; Fax: +39-0252-774306
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35
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Li KHC, Lee S, Yin C, Liu T, Ngarmukos T, Conte G, Yan GX, Sy RW, Letsas KP, Tse G. Brugada syndrome: A comprehensive review of pathophysiological mechanisms and risk stratification strategies. IJC HEART & VASCULATURE 2020; 26:100468. [PMID: 31993492 PMCID: PMC6974766 DOI: 10.1016/j.ijcha.2020.100468] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Revised: 01/01/2020] [Accepted: 01/02/2020] [Indexed: 12/17/2022]
Abstract
Brugada syndrome (BrS) is an inherited ion channel channelopathy predisposing to ventricular arrhythmias and sudden cardiac death. Originally believed to be predominantly associated with mutations in SCN5A encoding for the cardiac sodium channel, mutations of 18 genes other than SCN5A have been implicated in the pathogenesis of BrS to date. Diagnosis is based on the presence of a spontaneous or drug-induced coved-type ST segment elevation. The predominant electrophysiological mechanism underlying BrS remains disputed, commonly revolving around the three main hypotheses based on abnormal repolarization, depolarization or current-load match. Evidence from computational modelling, pre-clinical and clinical studies illustrates that molecular abnormalities found in BrS lead to alterations in excitation wavelength (λ), which ultimately elevates arrhythmic risk. A major challenge for clinicians in managing this condition is the difficulty in predicting the subset of patients who will suffer from life-threatening ventricular arrhythmic events. Several repolarization risk markers have been used thus far, but these neglect the contributions of conduction abnormalities in the form of slowing and dispersion. Indices incorporating both repolarization and conduction based on the concept of λ have recently been proposed. These may have better predictive values than the existing markers. Current treatment options include pharmacological therapy to reduce the occurrence of arrhythmic events or to abort these episodes, and interventions such as implantable cardioverter-defibrillator insertion or radiofrequency ablation of abnormal arrhythmic substrate.
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Affiliation(s)
- Ka Hou Christien Li
- Faculty of Medicine, Newcastle University, Newcastle, United Kingdom.,Laboratory of Cardiovascular Physiology, Li Ka Shing Institute of Health Sciences, Hong Kong, SAR, PR China
| | - Sharen Lee
- Laboratory of Cardiovascular Physiology, Li Ka Shing Institute of Health Sciences, Hong Kong, SAR, PR China
| | - Chengye Yin
- School of Biological and Chemical Sciences, Queen Mary University of London, London, United Kingdom
| | - Tong Liu
- Tianjin Key Laboratory of Ionic-Molecular Function of Cardiovascular Disease, Department of Cardiology, Tianjin Institute of Cardiology, Second Hospital of Tianjin Medical University, Tianjin 300211, PR China
| | - Tachapong Ngarmukos
- Department of Medicine Faculty of Medicine Ramathibodi Hospital Mahidol University, Bangkok, Thailand
| | - Giulio Conte
- Division of Cardiology, Cardiocentro Ticino, Lugano, Switzerland
| | - Gan-Xin Yan
- Lankenau Institute for Medical Research and Lankenau Medical Center, Wynnewood, PA, USA
| | - Raymond W Sy
- Department of Cardiology, Royal Prince Alfred Hospital, Camperdown, New South Wales, Australia.,Sydney Medical School, University of Sydney, Camperdown, New South Wales, Australia
| | - Konstantinos P Letsas
- Second Department of Cardiology, Laboratory of Cardiac Electrophysiology, Evangelismos General Hospital of Athens, Athens, Greece
| | - Gary Tse
- Tianjin Key Laboratory of Ionic-Molecular Function of Cardiovascular Disease, Department of Cardiology, Tianjin Institute of Cardiology, Second Hospital of Tianjin Medical University, Tianjin 300211, PR China.,Xiamen Cardiovascular Hospital, Xiamen University, Xiamen, China
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36
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Van de Sande DV, Kopljar I, Teisman A, Gallacher DJ, Snyders DJ, Lu HR, Labro AJ. Pharmacological Profile of the Sodium Current in Human Stem Cell-Derived Cardiomyocytes Compares to Heterologous Nav1.5+β1 Model. Front Pharmacol 2019; 10:1374. [PMID: 31920633 PMCID: PMC6917651 DOI: 10.3389/fphar.2019.01374] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2019] [Accepted: 10/29/2019] [Indexed: 12/20/2022] Open
Abstract
The cardiac Nav1.5 mediated sodium current (INa) generates the upstroke of the action potential in atrial and ventricular myocytes. Drugs that modulate this current can therefore be antiarrhythmic or proarrhythmic, which requires preclinical evaluation of their potential drug-induced inhibition or modulation of Nav1.5. Since Nav1.5 assembles with, and is modulated by, the auxiliary β1-subunit, this subunit can also affect the channel’s pharmacological response. To investigate this, the effect of known Nav1.5 inhibitors was compared between COS-7 cells expressing Nav1.5 or Nav1.5+β1 using whole-cell voltage clamp experiments. For the open state class Ia blockers ajmaline and quinidine, and class Ic drug flecainide, the affinity did not differ between both models. For class Ib drugs phenytoin and lidocaine, which are inactivated state blockers, the affinity decreased more than a twofold when β1 was present. Thus, β1 did not influence the affinity for the class Ia and Ic compounds but it did so for the class Ib drugs. Human stem cell-derived cardiomyocytes (hSC-CMs) are a promising translational cell source for in vitro models that express a representative repertoire of channels and auxiliary proteins, including β1. Therefore, we subsequently evaluated the same drugs for their response on the INa in hSC-CMs. Consequently, it was expected and confirmed that the drug response of INa in hSC-CMs compares best to INa expressed by Nav1.5+β1.
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Affiliation(s)
- Dieter V Van de Sande
- Laboratory of Molecular, Cellular, and Network Excitability, University of Antwerp, Antwerp, Belgium
| | - Ivan Kopljar
- Laboratory of Molecular, Cellular, and Network Excitability, University of Antwerp, Antwerp, Belgium.,Global Safety Pharmacology, Non-Clinical Safety, Janssen R&D, Beerse, Belgium
| | - Ard Teisman
- Global Safety Pharmacology, Non-Clinical Safety, Janssen R&D, Beerse, Belgium
| | - David J Gallacher
- Global Safety Pharmacology, Non-Clinical Safety, Janssen R&D, Beerse, Belgium
| | - Dirk J Snyders
- Laboratory of Molecular, Cellular, and Network Excitability, University of Antwerp, Antwerp, Belgium
| | - Hua Rong Lu
- Global Safety Pharmacology, Non-Clinical Safety, Janssen R&D, Beerse, Belgium
| | - Alain J Labro
- Laboratory of Molecular, Cellular, and Network Excitability, University of Antwerp, Antwerp, Belgium
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37
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Maroni M, Körner J, Schüttler J, Winner B, Lampert A, Eberhardt E. β1 and β3 subunits amplify mechanosensitivity of the cardiac voltage-gated sodium channel Nav1.5. Pflugers Arch 2019; 471:1481-1492. [PMID: 31728700 DOI: 10.1007/s00424-019-02324-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2019] [Revised: 09/25/2019] [Accepted: 10/21/2019] [Indexed: 12/19/2022]
Abstract
In cardiomyocytes, electrical activity is coupled to cellular contraction, thus exposing all proteins expressed in the sarcolemma to mechanical stress. The voltage-gated sodium channel Nav1.5 is the main contributor to the rising phase of the action potential in the heart. There is growing evidence that gating and kinetics of Nav1.5 are modulated by mechanical forces and pathogenic variants that affect mechanosensitivity have been linked to arrhythmias. Recently, the sodium channel β1 subunit has been described to stabilise gating against mechanical stress of Nav1.7 expressed in neurons. Here, we tested the effect of β1 and β3 subunits on mechanosensitivity of the cardiac Nav1.5. β1 amplifies stress-induced shifts of V1/2 of steady-state fast inactivation to hyperpolarised potentials (ΔV1/2: 6.2 mV without and 10.7 mV with β1 co-expression). β3, on the other hand, almost doubles stress-induced speeding of time to sodium current transient peak (Δtime to peak at - 30 mV: 0.19 ms without and 0.37 ms with β3 co-expression). Our findings may indicate that in cardiomyocytes, the interdependence of electrical activity and contraction is used as a means of fine tuning cardiac sodium channel function, allowing quicker but more strongly inactivating sodium currents under conditions of increased mechanical stress. This regulation may help to shorten action potential duration during tachycardia, to prevent re-entry phenomena and thus arrhythmias.
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Affiliation(s)
- Michele Maroni
- Department of Anaesthesiology, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 91054, Erlangen, Germany.,Department of Stem Cell Biology, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 91054, Erlangen, Germany
| | - Jannis Körner
- Institute of Physiology, Medical Faculty, RWTH Aachen University, 52074, Aachen, Germany.,Department of Anaesthesiology, Medical Faculty, RWTH Aachen University, 52074, Aachen, Germany
| | - Jürgen Schüttler
- Department of Anaesthesiology, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 91054, Erlangen, Germany
| | - Beate Winner
- Department of Stem Cell Biology, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 91054, Erlangen, Germany
| | - Angelika Lampert
- Institute of Physiology, Medical Faculty, RWTH Aachen University, 52074, Aachen, Germany
| | - Esther Eberhardt
- Department of Anaesthesiology, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 91054, Erlangen, Germany.
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El-Battrawy I, Müller J, Zhao Z, Cyganek L, Zhong R, Zhang F, Kleinsorge M, Lan H, Li X, Xu Q, Huang M, Liao Z, Moscu-Gregor A, Albers S, Dinkel H, Lang S, Diecke S, Zimmermann WH, Utikal J, Wieland T, Borggrefe M, Zhou X, Akin I. Studying Brugada Syndrome With an SCN1B Variants in Human-Induced Pluripotent Stem Cell-Derived Cardiomyocytes. Front Cell Dev Biol 2019; 7:261. [PMID: 31737628 PMCID: PMC6839339 DOI: 10.3389/fcell.2019.00261] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2019] [Accepted: 10/17/2019] [Indexed: 01/26/2023] Open
Abstract
Background Among rare channelopathies BrS patients are at high risk of sudden cardiac death (SCD). SCN5A mutations are found in a quarter of patients. Other rare gene mutations including SCN1B have been implicated to BrS. Studying the human cellular phenotype of BrS associated with rare gene mutation remains lacking. Objectives We sought to study the cellular phenotype of BrS with the SCN1B gene variants using human-induced pluripotent stem cell (hiPSCs)–derived cardiomyocytes (hiPSC-CMs). Methods and Results A BrS patient suffering from recurrent syncope harboring a two variants (c.629T > C and c.637C > A) in SCN1B, which encodes the function-modifying sodium channel beta1 subunit, and three independent healthy subjects were recruited and their skin biopsies were used to generate hiPSCs, which were differentiated into cardiomyocytes (hiPSC-CMs) for studying the cellular electrophysiology. A significantly reduced peak and late sodium channel current (INa) and a shift of activation curve to more positive potential as well as a shift of inactivation curve to more negative potential were detected in hiPSC-CMs of the BrS patient, indicating that the SCN1B variants impact the function of sodium channels in cardiomyocytes. The reduced INa led to a reduction of amplitude (APA) and upstroke velocity (Vmax) of action potentials. Ajmaline, a sodium channel blocker, showed a stronger effect on APA and Vmax in BrS cells as compared to cells from healthy donors. Furthermore, carbachol was able to increase arrhythmia events and the beating frequency in BrS. Conclusion Our hiPSC-CMs from a BrS-patient with two variants in SCN1B recapitulated some key phenotypic features of BrS and can provide a platform for studies on BrS with SCN1B variants.
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Affiliation(s)
- Ibrahim El-Battrawy
- First Department of Medicine, University Medical Centre Mannheim (UMM), Mannheim, Germany.,DZHK (German Center for Cardiovascular Research), Partner Sites Heidelberg-Mannheim and Göttingen, Mannheim, Germany
| | - Jonas Müller
- First Department of Medicine, University Medical Centre Mannheim (UMM), Mannheim, Germany.,DZHK (German Center for Cardiovascular Research), Partner Sites Heidelberg-Mannheim and Göttingen, Mannheim, Germany
| | - Zhihan Zhao
- First Department of Medicine, University Medical Centre Mannheim (UMM), Mannheim, Germany.,DZHK (German Center for Cardiovascular Research), Partner Sites Heidelberg-Mannheim and Göttingen, Mannheim, Germany
| | - Lukas Cyganek
- DZHK (German Center for Cardiovascular Research), Partner Sites Heidelberg-Mannheim and Göttingen, Mannheim, Germany.,Stem Cell Unit, Clinic for Cardiology and Pneumology, University Medical Center Göttingen, Göttingen, Germany
| | - Rujia Zhong
- First Department of Medicine, University Medical Centre Mannheim (UMM), Mannheim, Germany
| | - Feng Zhang
- First Department of Medicine, University Medical Centre Mannheim (UMM), Mannheim, Germany
| | - Mandy Kleinsorge
- DZHK (German Center for Cardiovascular Research), Partner Sites Heidelberg-Mannheim and Göttingen, Mannheim, Germany.,Stem Cell Unit, Clinic for Cardiology and Pneumology, University Medical Center Göttingen, Göttingen, Germany
| | - Huan Lan
- First Department of Medicine, University Medical Centre Mannheim (UMM), Mannheim, Germany.,DZHK (German Center for Cardiovascular Research), Partner Sites Heidelberg-Mannheim and Göttingen, Mannheim, Germany.,Key Laboratory of Medical Electrophysiology of Ministry of Education and Medical Electrophysiological, Key Laboratory of Sichuan Province, Institute of Cardiovascular Research, Southwest Medical University, Luzhou, China
| | - Xin Li
- First Department of Medicine, University Medical Centre Mannheim (UMM), Mannheim, Germany
| | - Qiang Xu
- First Department of Medicine, University Medical Centre Mannheim (UMM), Mannheim, Germany
| | - Mengying Huang
- First Department of Medicine, University Medical Centre Mannheim (UMM), Mannheim, Germany
| | - Zhenxing Liao
- First Department of Medicine, University Medical Centre Mannheim (UMM), Mannheim, Germany
| | | | - Sebastian Albers
- First Department of Medicine, University Medical Centre Mannheim (UMM), Mannheim, Germany.,DZHK (German Center for Cardiovascular Research), Partner Sites Heidelberg-Mannheim and Göttingen, Mannheim, Germany
| | - Hendrik Dinkel
- First Department of Medicine, University Medical Centre Mannheim (UMM), Mannheim, Germany
| | - Siegfried Lang
- First Department of Medicine, University Medical Centre Mannheim (UMM), Mannheim, Germany.,DZHK (German Center for Cardiovascular Research), Partner Sites Heidelberg-Mannheim and Göttingen, Mannheim, Germany
| | | | - Wolfram-Hubertus Zimmermann
- DZHK (German Center for Cardiovascular Research), Partner Sites Heidelberg-Mannheim and Göttingen, Mannheim, Germany.,Institute of Pharmacology and Toxicology, University of Göttingen, Göttingen, Germany
| | - Jochen Utikal
- DZHK (German Center for Cardiovascular Research), Partner Sites Heidelberg-Mannheim and Göttingen, Mannheim, Germany.,Skin Cancer Unit, German Cancer Research Center (DKFZ), Heidelberg and Department of Dermatology, Venereology and Allergology, University Medical Center Mannheim, University of Heidelberg, Mannheim, Germany
| | - Thomas Wieland
- DZHK (German Center for Cardiovascular Research), Partner Sites Heidelberg-Mannheim and Göttingen, Mannheim, Germany.,Institute of Experimental and Clinical Pharmacology and Toxicology, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
| | - Martin Borggrefe
- First Department of Medicine, University Medical Centre Mannheim (UMM), Mannheim, Germany.,DZHK (German Center for Cardiovascular Research), Partner Sites Heidelberg-Mannheim and Göttingen, Mannheim, Germany
| | - Xiaobo Zhou
- First Department of Medicine, University Medical Centre Mannheim (UMM), Mannheim, Germany.,DZHK (German Center for Cardiovascular Research), Partner Sites Heidelberg-Mannheim and Göttingen, Mannheim, Germany.,Key Laboratory of Medical Electrophysiology of Ministry of Education and Medical Electrophysiological, Key Laboratory of Sichuan Province, Institute of Cardiovascular Research, Southwest Medical University, Luzhou, China
| | - Ibrahim Akin
- First Department of Medicine, University Medical Centre Mannheim (UMM), Mannheim, Germany.,DZHK (German Center for Cardiovascular Research), Partner Sites Heidelberg-Mannheim and Göttingen, Mannheim, Germany
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Cortada E, Brugada R, Verges M. Trafficking and Function of the Voltage-Gated Sodium Channel β2 Subunit. Biomolecules 2019; 9:biom9100604. [PMID: 31614896 PMCID: PMC6843408 DOI: 10.3390/biom9100604] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Revised: 10/07/2019] [Accepted: 10/08/2019] [Indexed: 12/15/2022] Open
Abstract
The voltage-gated sodium channel is vital for cardiomyocyte function, and consists of a protein complex containing a pore-forming α subunit and two associated β subunits. A fundamental, yet unsolved, question is to define the precise function of β subunits. While their location in vivo remains unclear, large evidence shows that they regulate localization of α and the biophysical properties of the channel. The current data support that one of these subunits, β2, promotes cell surface expression of α. The main α isoform in an adult heart is NaV1.5, and mutations in SCN5A, the gene encoding NaV1.5, often lead to hereditary arrhythmias and sudden death. The association of β2 with cardiac arrhythmias has also been described, which could be due to alterations in trafficking, anchoring, and localization of NaV1.5 at the cardiomyocyte surface. Here, we will discuss research dealing with mechanisms that regulate β2 trafficking, and how β2 could be pivotal for the correct localization of NaV1.5, which influences cellular excitability and electrical coupling of the heart. Moreover, β2 may have yet to be discovered roles on cell adhesion and signaling, implying that diverse defects leading to human disease may arise due to β2 mutations.
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Affiliation(s)
- Eric Cortada
- Cardiovascular Genetics Group, Girona Biomedical Research Institute (IDIBGI), C/ Doctor Castany, s/n-Edifici IDIBGI, 17190 Girona, Spain.
- Biomedical Research Networking Center on Cardiovascular Diseases (CIBERCV), 28029 Madrid, Spain.
| | - Ramon Brugada
- Cardiovascular Genetics Group, Girona Biomedical Research Institute (IDIBGI), C/ Doctor Castany, s/n-Edifici IDIBGI, 17190 Girona, Spain.
- Biomedical Research Networking Center on Cardiovascular Diseases (CIBERCV), 28029 Madrid, Spain.
- Medical Sciences Department, University of Girona Medical School, 17003 Girona, Spain.
- Cardiology Department, Hospital Josep Trueta, 17007 Girona, Spain.
| | - Marcel Verges
- Cardiovascular Genetics Group, Girona Biomedical Research Institute (IDIBGI), C/ Doctor Castany, s/n-Edifici IDIBGI, 17190 Girona, Spain.
- Biomedical Research Networking Center on Cardiovascular Diseases (CIBERCV), 28029 Madrid, Spain.
- Medical Sciences Department, University of Girona Medical School, 17003 Girona, Spain.
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40
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Cortada E, Brugada R, Verges M. N-Glycosylation of the voltage-gated sodium channel β2 subunit is required for efficient trafficking of Na V1.5/β2 to the plasma membrane. J Biol Chem 2019; 294:16123-16140. [PMID: 31511323 DOI: 10.1074/jbc.ra119.007903] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Revised: 09/01/2019] [Indexed: 01/25/2023] Open
Abstract
The voltage-gated sodium channel is critical for cardiomyocyte function and consists of a protein complex comprising a pore-forming α subunit and two associated β subunits. It has been shown previously that the associated β2 subunits promote cell surface expression of the α subunit. The major α isoform in the adult human heart is NaV1.5, and germline mutations in the NaV1.5-encoding gene, sodium voltage-gated channel α subunit 5 (SCN5A), often cause inherited arrhythmias. Here, we investigated the mechanisms that regulate β2 trafficking and how they may determine proper NaV1.5 cell surface localization. Using heterologous expression in polarized Madin-Darby canine kidney cells, we show that β2 is N-glycosylated in vivo and in vitro at residues 42, 66, and 74, becoming sialylated only at Asn-42. We found that fully nonglycosylated β2 was mostly retained in the endoplasmic reticulum, indicating that N-linked glycosylation is required for efficient β2 trafficking to the apical plasma membrane. The nonglycosylated variant reached the cell surface by bypassing the Golgi compartment at a rate of only approximately one-third of that of WT β2. YFP-tagged, nonglycosylated β2 displayed mobility kinetics in the plane of the membrane similar to that of WT β2. However, it was defective in promoting surface localization of NaV1.5. Interestingly, β2 with a single intact glycosylation site was as effective as the WT in promoting NaV1.5 surface localization. In conclusion, our results indicate that N-linked glycosylation of β2 is required for surface localization of NaV1.5, a property that is often defective in inherited cardiac arrhythmias.
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Affiliation(s)
- Eric Cortada
- Cardiovascular Genetics Group-Girona Biomedical Research Institute (IDIBGI), University of Girona Medical School, C/ Doctor Castany, s/n-Edifici IDIBGI, 17190 Salt-Prov. Girona, Spain.,Biomedical Research Networking Center on Cardiovascular Diseases (CIBERCV), University of Girona Medical School, C/ Doctor Castany, s/n-Edifici IDIBGI, 17190 Salt-Prov. Girona, Spain
| | - Ramon Brugada
- Cardiovascular Genetics Group-Girona Biomedical Research Institute (IDIBGI), University of Girona Medical School, C/ Doctor Castany, s/n-Edifici IDIBGI, 17190 Salt-Prov. Girona, Spain.,Biomedical Research Networking Center on Cardiovascular Diseases (CIBERCV), University of Girona Medical School, C/ Doctor Castany, s/n-Edifici IDIBGI, 17190 Salt-Prov. Girona, Spain.,Medical Sciences Department, University of Girona Medical School, C/ Doctor Castany, s/n-Edifici IDIBGI, 17190 Salt-Prov. Girona, Spain.,Cardiology Department, Hospital Josep Trueta, University of Girona Medical School, C/ Doctor Castany, s/nγÇôEdifici IDIBGI, 17190 SaltγÇôProv. Girona, Spain
| | - Marcel Verges
- Cardiovascular Genetics Group-Girona Biomedical Research Institute (IDIBGI), University of Girona Medical School, C/ Doctor Castany, s/n-Edifici IDIBGI, 17190 Salt-Prov. Girona, Spain .,Biomedical Research Networking Center on Cardiovascular Diseases (CIBERCV), University of Girona Medical School, C/ Doctor Castany, s/n-Edifici IDIBGI, 17190 Salt-Prov. Girona, Spain.,Medical Sciences Department, University of Girona Medical School, C/ Doctor Castany, s/n-Edifici IDIBGI, 17190 Salt-Prov. Girona, Spain
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41
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Hu RM, Tester DJ, Li R, Sun T, Peterson BZ, Ackerman MJ, Makielski JC, Tan BH. Mexiletine rescues a mixed biophysical phenotype of the cardiac sodium channel arising from the SCN5A mutation, N406K, found in LQT3 patients. Channels (Austin) 2019; 12:176-186. [PMID: 29983085 PMCID: PMC6104686 DOI: 10.1080/19336950.2018.1475794] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Introduction: Individual mutations in the SCN5A-encoding cardiac sodium channel α-subunit usually cause a single cardiac arrhythmia disorder, some cause mixed biophysical or clinical phenotypes. Here we report an infant, female patient harboring a N406K mutation in SCN5A with a marked and mixed biophysical phenotype and assess pathogenic mechanisms. Methods and Results: A patient suffered from recurrent seizures during sleep and torsades de pointes with a QTc of 530 ms. Mutational analysis identified a N406K mutation in SCN5A. The mutation was engineered by site-directed mutagenesis and heterologously expressed in HEK293 cells. After 48 hours incubation with and without mexiletine, macroscopic voltage-gated sodium current (INa) was measured with standard whole-cell patch clamp techniques. SCN5A-N406K elicited both a significantly decreased peak INa and a significantly increased late INa compared to wide-type (WT) channels. Furthermore, mexiletine both restored the decreased peak INa of the mutant channel and inhibited the increased late INa of the mutant channel. Conclusion: SCN5A-N406K channel displays both “gain-of-function” in late INa and “loss-of-function” in peak INa density contributing to a mixed biophysical phenotype. Moreover, our finding may provide the first example that mexiletine exerts a dual rescue of both “gain-of-function” and “loss-of-function” of the mutant sodium channel.
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Affiliation(s)
- Rou-Mu Hu
- a Heart Center & Beijing Key Laboratory of Hypertension, Beijing Chaoyang Hospital , Capital Medical University , Beijing , China.,b Division of Cardiovascular Medicine, Department of Medicine , University of Wisconsin , Madison , Wisconsin , USA
| | - David J Tester
- c Departments of Medicine, Pediatrics, and Molecular Pharmacology and Experimental Therapeutics , Mayo Clinic , Rochester , MN , USA
| | - Ryan Li
- d Departments of Pediatrics, and Cellular & Molecular Physiology , Pennsylvania State University College of Medicine , Hershey , PA , USA
| | - Tianyu Sun
- d Departments of Pediatrics, and Cellular & Molecular Physiology , Pennsylvania State University College of Medicine , Hershey , PA , USA
| | - Blaise Z Peterson
- d Departments of Pediatrics, and Cellular & Molecular Physiology , Pennsylvania State University College of Medicine , Hershey , PA , USA
| | - Michael J Ackerman
- c Departments of Medicine, Pediatrics, and Molecular Pharmacology and Experimental Therapeutics , Mayo Clinic , Rochester , MN , USA
| | - Jonathan C Makielski
- b Division of Cardiovascular Medicine, Department of Medicine , University of Wisconsin , Madison , Wisconsin , USA
| | - Bi-Hua Tan
- b Division of Cardiovascular Medicine, Department of Medicine , University of Wisconsin , Madison , Wisconsin , USA.,d Departments of Pediatrics, and Cellular & Molecular Physiology , Pennsylvania State University College of Medicine , Hershey , PA , USA
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Abstract
Brugada syndrome is an inherited, rare cardiac arrhythmogenic disease, associated with sudden cardiac death. It accounts for up to 20% of sudden deaths in patients without structural cardiac abnormalities. The majority of mutations involve the cardiac sodium channel gene SCN5A and give rise to classical abnormal electrocardiogram with ST segment elevation in the right precordial leads V1 to V3 and a predisposition to ventricular fibrillation. The pathophysiological mechanisms of Brugada syndrome have been investigated using model systems including transgenic mice, canine heart preparations, and expression systems to study different SCN5A mutations. These models have a number of limitations. The recent development of pluripotent stem cell technology creates an opportunity to study cardiomyocytes derived from patients and healthy individuals. To date, only a few studies have been done using Brugada syndrome patient-specific iPS-CM, which have provided novel insights into the mechanisms and pathophysiology of Brugada syndrome. This review provides an evaluation of the strengths and limitations of each of these model systems and summarizes the key mechanisms that have been identified to date.
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The role of the gap junction perinexus in cardiac conduction: Potential as a novel anti-arrhythmic drug target. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2018; 144:41-50. [PMID: 30241906 DOI: 10.1016/j.pbiomolbio.2018.08.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Revised: 07/09/2018] [Accepted: 08/10/2018] [Indexed: 12/16/2022]
Abstract
Cardiovascular disease remains the single largest cause of natural death in the United States, with a significant cause of mortality associated with cardiac arrhythmias. Presently, options for treating and preventing myocardial electrical dysfunction, including sudden cardiac death, are limited. Recent studies have indicated that conduction of electrical activation in the heart may have an ephaptic component, wherein intercellular coupling occurs via electrochemical signaling across narrow extracellular clefts between cardiomyocytes. The perinexus is a 100-200 nm-wide stretch of closely apposed membrane directly adjacent to connexin 43 gap junctions. Electron and super-resolution microscopy studies, as well as biochemical analyses, have provided evidence that perinexal nanodomains may be candidate structures for facilitating ephaptic coupling. This work has included characterization of the perinexus as a region of close inter-membrane contact between cardiomyocytes (<30 nm) containing dense clusters of voltage-gated sodium channels. Here, we review what is known about perinexal structure and function and the potential that the perinexus may have novel and pivotal roles in disorders of cardiac conduction. Of particular interest is the prospect that cell adhesion mediated by the cardiac sodium channel β subunit (Scn1b) may be a novel anti-arrhythmic target.
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44
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He BJ, Boyden P, Scheinman M. Ventricular arrhythmias involving the His-Purkinje system in the structurally abnormal heart. PACING AND CLINICAL ELECTROPHYSIOLOGY: PACE 2018; 41:1051-1059. [PMID: 30084120 DOI: 10.1111/pace.13465] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Revised: 06/28/2018] [Accepted: 07/05/2018] [Indexed: 12/01/2022]
Abstract
His-Purkinje-related ventricular arrhythmias are a subset of ventricular tachycardias that use the specialized cardiac conduction system. These arrhythmias can occur in various different forms of structural heart disease. Here, we review the basic science discoveries and their analogous clinical observations that implicate the His-Purkinje system as a crucial component of the arrhythmia circuit. While mutations serve the molecular basis for arrhythmias in the heritable cardiomyopathies, transcriptional and posttranslational changes constitute the adverse remodeling leading to arrhythmias in acquired structural heart disease. Additional studies on the electrical properties of the His-Purkinje network and its interactions with the surrounding myocardium will improve the clinical diagnosis and treatment of these arrhythmias.
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Affiliation(s)
- Beixin Julie He
- Department of Medicine, University of California, San Francisco, California
| | - Penelope Boyden
- Department of Pharmacology, Columbia University, New York city, New York
| | - Melvin Scheinman
- Department of Medicine, University of California, San Francisco, California
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45
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Monasky MM, Pappone C, Piccoli M, Ghiroldi A, Micaglio E, Anastasia L. Calcium in Brugada Syndrome: Questions for Future Research. Front Physiol 2018; 9:1088. [PMID: 30147658 PMCID: PMC6095984 DOI: 10.3389/fphys.2018.01088] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Accepted: 07/23/2018] [Indexed: 12/11/2022] Open
Abstract
The Brugada syndrome (BrS) is characterized by coved-type ST-segment elevation in the right precordial leads on the electrocardiogram (ECG) and increased risk of sudden cardiac death (SCD). While it is an inheritable disease, determining the true prevalence is a challenge, since patients may report no known family history of the syndrome, present with a normal spontaneous ECG pattern at the time of examination, and test negative for all known BrS-causative genes. In fact, SCD is often the first indication that a person is affected by the syndrome. Men are more likely to be symptomatic than women. Abnormal, low-voltage, fractionated electrograms have been found in the epicardium of the right ventricular outflow tract (RVOT). Ablation of this area abolishes the abnormal electrograms and helps to prevent arrhythmic recurrences. BrS patients are more likely to experience ventricular tachycardia/fibrillation (VT/VF) during fever or during an increase in vagal tone. Isoproterenol helps to reverse the ECG BrS phenotype. In this review, we discuss roles of calcium in various conditions that are relevant to BrS, such as changes in temperature, heart rate, and vagal tone, and the effects of gender and isoproterenol on calcium handling. Studies are warranted to further investigate these mechanisms in models of BrS.
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Affiliation(s)
| | - Carlo Pappone
- Arrhythmology Department, IRCCS Policlinico San Donato, Milan, Italy
| | - Marco Piccoli
- Stem Cells for Tissue Engineering Lab, IRCCS Policlinico San Donato, Milan, Italy
| | - Andrea Ghiroldi
- Stem Cells for Tissue Engineering Lab, IRCCS Policlinico San Donato, Milan, Italy
| | - Emanuele Micaglio
- Arrhythmology Department, IRCCS Policlinico San Donato, Milan, Italy
| | - Luigi Anastasia
- Stem Cells for Tissue Engineering Lab, IRCCS Policlinico San Donato, Milan, Italy.,Department of Biomedical Sciences for Health, University of Milan, Milan, Italy
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46
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Boyden PA. Purkinje physiology and pathophysiology. J Interv Card Electrophysiol 2018; 52:255-262. [PMID: 30056516 DOI: 10.1007/s10840-018-0414-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Accepted: 07/17/2018] [Indexed: 01/08/2023]
Abstract
There has always been an appreciation of the role of Purkinje fibers in the fast conduction of the normal cardiac impulse. Here, we briefly update our knowledge of this important set of cardiac cells. We discuss the anatomy of a Purkinje fiber strand, the importance of longitudinal conduction within a strand, circus movement within a strand, conduction, and excitability properties of Purkinjes. At the cell level, we discuss the important components of the ion channel makeup in the nonremodeled Purkinjes of healthy hearts. Finally, we discuss the role of the Purkinjes in forming the heritable arrhythmogenic substrates such as long QT, heritable conduction slowing, CPVT, sQT, and Brugada syndromes.
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Affiliation(s)
- Penelope A Boyden
- Department of Pharmacology, Columbia University, New York, NY, 10032, USA.
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47
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Human iPSC-Derived Cardiomyocytes for Investigation of Disease Mechanisms and Therapeutic Strategies in Inherited Arrhythmia Syndromes: Strengths and Limitations. Cardiovasc Drugs Ther 2018; 31:325-344. [PMID: 28721524 PMCID: PMC5550530 DOI: 10.1007/s10557-017-6735-0] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
During the last two decades, significant progress has been made in the identification of genetic defects underlying inherited arrhythmia syndromes, which has provided some clinical benefit through elucidation of gene-specific arrhythmia triggers and treatment. However, for most arrhythmia syndromes, clinical management is hindered by insufficient knowledge of the functional consequences of the mutation in question, the pro-arrhythmic mechanisms involved, and hence the most optimal treatment strategy. Moreover, disease expressivity and sensitivity to therapeutic interventions often varies between mutations and/or patients, underlining the need for more individualized strategies. The development of the induced pluripotent stem cell (iPSC) technology now provides the opportunity for generating iPSC-derived cardiomyocytes (CMs) from human material (hiPSC-CMs), enabling patient- and/or mutation-specific investigations. These hiPSC-CMs may furthermore be employed for identification and assessment of novel therapeutic strategies for arrhythmia syndromes. However, due to their relative immaturity, hiPSC-CMs also display a number of essential differences as compared to adult human CMs, and hence there are certain limitations in their use. We here review the electrophysiological characteristics of hiPSC-CMs, their use for investigating inherited arrhythmia syndromes, and their applicability for identification and assessment of (novel) anti-arrhythmic treatment strategies.
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48
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Abe KT, Rizzo IMPO, Coelho ALV, Sakai N, Carvalho DR, Speck‐Martins CE. 19q13.11 microdeletion: Clinical features overlapping ectrodactyly ectodermal dysplasia-clefting syndrome phenotype. Clin Case Rep 2018; 6:1300-1307. [PMID: 29988626 PMCID: PMC6028370 DOI: 10.1002/ccr3.1600] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Revised: 03/20/2018] [Accepted: 04/26/2018] [Indexed: 11/08/2022] Open
Abstract
We report a patient who was followed for a long time under an ectrodactyly ectodermal dysplasia-clefting (EEC) syndrome and was subsequently diagnosed with a 19q13.11 microdeletion. After a review of the related literature, we suggest testing patients with EEC for 19q13.11 microdeletion and include WTIP and UBA2 to a minimal overlapping region.
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Affiliation(s)
- Kikue Terada Abe
- Cytogenetic LaboratoryMolecular PathologySARAH Network of Rehabilitation HospitalsBrasíliaBrazil
| | | | - Ana L. V. Coelho
- Department of Clinical GeneticsSARAH Network of Rehabilitation HospitalsBrasíliaBrazil
| | - Nilo Sakai
- Cytogenetic LaboratoryMolecular PathologySARAH Network of Rehabilitation HospitalsBrasíliaBrazil
| | - Daniel R. Carvalho
- Department of Clinical GeneticsSARAH Network of Rehabilitation HospitalsBrasíliaBrazil
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49
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Calloe K, Aistrup GL, Di Diego JM, Goodrow RJ, Treat JA, Cordeiro JM. Interventricular differences in sodium current and its potential role in Brugada syndrome. Physiol Rep 2018; 6:e13787. [PMID: 30009404 PMCID: PMC6046646 DOI: 10.14814/phy2.13787] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Revised: 06/14/2018] [Accepted: 06/15/2018] [Indexed: 12/19/2022] Open
Abstract
Brugada syndrome (BrS) is an inherited disease associated with ST elevation in the right precordial leads, polymorphic ventricular tachycardia (PVT), and sudden cardiac death in adults. Mutations in the cardiac sodium channel account for a large fraction of BrS cases. BrS manifests in the right ventricle (RV), which led us to examine the biophysical and molecular properties of sodium channel in myocytes isolated from the left (LV) and right ventricle. Patch clamp was used to record sodium current (INa ) in single canine RV and LV epicardial (epi) and endocardial (endo) myocytes. Action potentials were recorded from multicellular preparations and single cells. mRNA and proteins were determined using quantitative RT-PCR and Western blot. Although LV wedge preparations were thicker than RV wedges, transmural ECG recordings showed no difference in the width of the QRS complex or transmural conduction time. Action potential characteristics showed RV epi and endo had a lower Vmax compared with LV epi and endo cells. Peak INa density was significantly lower in epi and endo RV cells compared with epi and endo LV cells. Recovery from inactivation of INa in RV cells was slightly faster and half maximal steady-state inactivation was more positive. β2 and β4 mRNA was detected at very low levels in both ventricles, which was confirmed at the protein level. Our observations demonstrate that Vmax and Na+ current are smaller in RV, presumably due to differential Nav 1.5/β subunit expression. These results provide a potential mechanism for the right ventricular manifestation of BrS.
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Affiliation(s)
- Kirstine Calloe
- Department of Veterinary and Animal SciencesSection for Anatomy, Biochemistry and PhysiologyUniversity of CopenhagenFrederiksbergDenmark
| | - Gary L. Aistrup
- Department of Experimental CardiologyMasonic Medical Research LaboratoryUticaNew York
| | - José M. Di Diego
- Department of Experimental CardiologyMasonic Medical Research LaboratoryUticaNew York
- Lankenau Institute for Medical ResearchWynnewoodPennsylvania
| | - Robert J. Goodrow
- Department of Experimental CardiologyMasonic Medical Research LaboratoryUticaNew York
| | - Jacqueline A. Treat
- Department of Experimental CardiologyMasonic Medical Research LaboratoryUticaNew York
| | - Jonathan M. Cordeiro
- Department of Experimental CardiologyMasonic Medical Research LaboratoryUticaNew York
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Abstract
INTRODUCTION Brugada syndrome (BrS) is an inherited cardiac arrhythmia syndrome characterized by ST-segment elevation in right precordial ECG leads and associated with sudden cardiac death in young adults. The ECG manifestations of BrS are often concealed but can be unmasked by sodium channel blockers and fever. Areas covered: Implantation of a cardioverter defibrillator (ICD) is first-line therapy for BrS patients presenting with prior cardiac arrest or documented VT. A pharmacological approach to therapy is recommended in cases of electrical storm, as an adjunct to ICD and as preventative therapy. The goal of pharmacological therapy is to produce an inward shift to counter the genetically-induced outward shift of ion channel current flowing during the early phases of the ventricular epicardial action potential. This is accomplished by augmentation of ICa using □□adrenergic agents or phosphodiesterase III inhibitors or via inhibition of Ito. Radiofrequency ablation of the right ventricular outward flow tract epicardium is effective in suppressing arrhythmogenesis in BrS patients experiencing frequent appropriate ICD-shocks. Expert commentary: Understanding of the pathophysiology and approach to therapy of BrS has advanced considerably in recent years, but there remains an urgent need for development of cardio-selective and ion-channel-specific Ito blockers for treatment of BrS.
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Affiliation(s)
- Mariana Argenziano
- a Cardiovascular Research , Lankenau Institute for Medical Research , Wynnewood , PA , USA
| | - Charles Antzelevitch
- a Cardiovascular Research , Lankenau Institute for Medical Research , Wynnewood , PA , USA.,b Cardiovascular Research , Lankenau Heart Institute , Wynnewood , PA , USA.,c Department of Medicine and Pharmacology and Experimental Therapeutics , Sidney Kimmel Medical College of Thomas Jefferson University , Philadelphia , PA , USA
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