1
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Absolute Quantification of Nav1.5 Expression by Targeted Mass Spectrometry. Int J Mol Sci 2022; 23:ijms23084177. [PMID: 35456996 PMCID: PMC9028338 DOI: 10.3390/ijms23084177] [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: 03/17/2022] [Revised: 04/07/2022] [Accepted: 04/08/2022] [Indexed: 11/20/2022] Open
Abstract
Nav1.5 is the pore forming α-subunit of the cardiac voltage-gated sodium channel that initiates cardiac action potential and regulates the human heartbeat. A normal level of Nav1.5 is crucial to cardiac function and health. Over- or under-expression of Nav1.5 can cause various cardiac diseases ranging from short PR intervals to Brugada syndromes. An assay that can directly quantify the protein amount in biological samples would be a priori to accurately diagnose and treat Nav1.5-associated cardiac diseases. Due to its large size (>200 KD), multipass transmembrane domains (24 transmembrane passes), and heavy modifications, Nav1.5 poses special quantitation challenges. To date, only the relative quantities of this protein have been measured in biological samples. Here, we describe the first targeted and mass spectrometry (MS)-based quantitative assay that can provide the copy numbers of Nav1.5 in cells with a well-defined lower limit of quantification (LLOQ) and precision. Applying the developed assay, we successfully quantified transiently expressed Nav1.5 in as few as 1.5 million Chinese hamster ovary (CHO) cells. The obtained quantity was 3 ± 2 fmol on the column and 3 ± 2 × 104 copies/cell. To our knowledge, this is the first absolute quantity of Nav1.5 measured in a biological sample.
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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: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Revised: 12/30/2021] [Accepted: 01/06/2022] [Indexed: 12/19/2022] Open
Abstract
Nav1.5 is the predominant cardiac sodium channel subtype, encoded by the SCN5A gene, which is involved in the initiation and conduction of action potentials throughout the heart. Along its biosynthesis process, Nav1.5 undergoes strict genomic and non-genomic regulatory and quality control steps that allow only newly synthesized channels to reach their final membrane destination and carry out their electrophysiological role. These regulatory pathways are ensured by distinct interacting proteins that accompany the nascent Nav1.5 protein along with different subcellular organelles. Defects on a large number of these pathways have a tremendous impact on Nav1.5 functionality and are thus intimately linked to cardiac arrhythmias. In the present review, we provide current state-of-the-art information on the molecular events that regulate SCN5A/Nav1.5 and the cardiac channelopathies associated with defects in these pathways.
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Affiliation(s)
- Houria Daimi
- Biochemistry and Molecular Biology Laboratory, Faculty of Pharmacy, University of Monastir, Monastir 5000, Tunisia
| | - Estefanía Lozano-Velasco
- Department of Experimental Biology, University of Jaen, 23071 Jaen, Spain; (E.L.-V.); (A.A.); (D.F.)
- Medina Foundation, Technology Park of Health Sciences, Av. del Conocimiento, 34, 18016 Granada, Spain
| | - Amelia Aranega
- Department of Experimental Biology, University of Jaen, 23071 Jaen, Spain; (E.L.-V.); (A.A.); (D.F.)
- Medina Foundation, Technology Park of Health Sciences, Av. del Conocimiento, 34, 18016 Granada, Spain
| | - Diego Franco
- Department of Experimental Biology, University of Jaen, 23071 Jaen, Spain; (E.L.-V.); (A.A.); (D.F.)
- Medina Foundation, Technology Park of Health Sciences, Av. del Conocimiento, 34, 18016 Granada, Spain
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3
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Pinsach-Abuin M, del Olmo B, Pérez-Agustin A, Mates J, Allegue C, Iglesias A, Ma Q, Merkurjev D, Konovalov S, Zhang J, Sheikh F, Telenti A, Brugada J, Brugada R, Gymrek M, di Iulio J, Garcia-Bassets I, Pagans S. Analysis of Brugada syndrome loci reveals that fine-mapping clustered GWAS hits enhances the annotation of disease-relevant variants. Cell Rep Med 2021; 2:100250. [PMID: 33948580 PMCID: PMC8080235 DOI: 10.1016/j.xcrm.2021.100250] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Revised: 01/07/2021] [Accepted: 03/23/2021] [Indexed: 11/30/2022]
Abstract
Genome-wide association studies (GWASs) are instrumental in identifying loci harboring common single-nucleotide variants (SNVs) that affect human traits and diseases. GWAS hits emerge in clusters, but the focus is often on the most significant hit in each trait- or disease-associated locus. The remaining hits represent SNVs in linkage disequilibrium (LD) and are considered redundant and thus frequently marginally reported or exploited. Here, we interrogate the value of integrating the full set of GWAS hits in a locus repeatedly associated with cardiac conduction traits and arrhythmia, SCN5A-SCN10A. Our analysis reveals 5 common 7-SNV haplotypes (Hap1-5) with 2 combinations associated with life-threatening arrhythmia-Brugada syndrome (the risk Hap1/1 and protective Hap2/3 genotypes). Hap1 and Hap2 share 3 SNVs; thus, this analysis suggests that assuming redundancy among clustered GWAS hits can lead to confounding disease-risk associations and supports the need to deconstruct GWAS data in the context of haplotype composition.
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Affiliation(s)
- Mel·lina Pinsach-Abuin
- Department of Medical Sciences, School of Medicine, Universitat de Girona, Girona, Spain
- Visiting Scholar Program, Department of Medicine, School of Medicine, University of California, San Diego, La Jolla, CA, USA
- Institut d’Investigació Biomèdica de Girona, Salt, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Cardiovasculares, Madrid, Spain
| | - Bernat del Olmo
- Department of Medical Sciences, School of Medicine, Universitat de Girona, Girona, Spain
- Visiting Scholar Program, Department of Medicine, School of Medicine, University of California, San Diego, La Jolla, CA, USA
- Institut d’Investigació Biomèdica de Girona, Salt, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Cardiovasculares, Madrid, Spain
| | - Adrian Pérez-Agustin
- Department of Medical Sciences, School of Medicine, Universitat de Girona, Girona, Spain
- Institut d’Investigació Biomèdica de Girona, Salt, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Cardiovasculares, Madrid, Spain
| | - Jesus Mates
- Department of Medical Sciences, School of Medicine, Universitat de Girona, Girona, Spain
- Institut d’Investigació Biomèdica de Girona, Salt, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Cardiovasculares, Madrid, Spain
| | - Catarina Allegue
- Department of Medical Sciences, School of Medicine, Universitat de Girona, Girona, Spain
- Visiting Scholar Program, Department of Medicine, School of Medicine, University of California, San Diego, La Jolla, CA, USA
- Institut d’Investigació Biomèdica de Girona, Salt, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Cardiovasculares, Madrid, Spain
| | - Anna Iglesias
- Department of Medical Sciences, School of Medicine, Universitat de Girona, Girona, Spain
- Institut d’Investigació Biomèdica de Girona, Salt, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Cardiovasculares, Madrid, Spain
| | - Qi Ma
- Department of Medicine, School of Medicine, University of California, San Diego, La Jolla, CA, USA
| | - Daria Merkurjev
- Department of Medicine, School of Medicine, University of California, San Diego, La Jolla, CA, USA
- Department of Statistics, University of California, Los Angeles, Los Angeles, CA, USA
| | - Sergiy Konovalov
- Department of Medicine, School of Medicine, University of California, San Diego, La Jolla, CA, USA
| | - Jing Zhang
- Department of Medicine, School of Medicine, University of California, San Diego, La Jolla, CA, USA
| | - Farah Sheikh
- Department of Medicine, School of Medicine, University of California, San Diego, La Jolla, CA, USA
| | - Amalio Telenti
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA, USA
| | - Josep Brugada
- Arrhythmia Unit, Hospital Clinic de Barcelona, Universitat de Barcelona, Barcelona, Spain
| | - Ramon Brugada
- Department of Medical Sciences, School of Medicine, Universitat de Girona, Girona, Spain
- Institut d’Investigació Biomèdica de Girona, Salt, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Cardiovasculares, Madrid, Spain
- Cardiology Service, Hospital Universitari Dr. Josep Trueta, Girona, Spain
| | - Melissa Gymrek
- Department of Medicine, School of Medicine, University of California, San Diego, La Jolla, CA, USA
- Department of Computer Science and Engineering, University of California, San Diego, La Jolla, CA, USA
| | - Julia di Iulio
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA, USA
| | - Ivan Garcia-Bassets
- Department of Medicine, School of Medicine, University of California, San Diego, La Jolla, CA, USA
| | - Sara Pagans
- Department of Medical Sciences, School of Medicine, Universitat de Girona, Girona, Spain
- Institut d’Investigació Biomèdica de Girona, Salt, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Cardiovasculares, Madrid, Spain
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iPSC-Cardiomyocyte Models of Brugada Syndrome-Achievements, Challenges and Future Perspectives. Int J Mol Sci 2021; 22:ijms22062825. [PMID: 33802229 PMCID: PMC8001521 DOI: 10.3390/ijms22062825] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2021] [Revised: 03/02/2021] [Accepted: 03/03/2021] [Indexed: 12/19/2022] Open
Abstract
Brugada syndrome (BrS) is an inherited cardiac arrhythmia that predisposes to ventricular fibrillation and sudden cardiac death. It originates from oligogenic alterations that affect cardiac ion channels or their accessory proteins. The main hurdle for the study of the functional effects of those variants is the need for a specific model that mimics the complex environment of human cardiomyocytes. Traditionally, animal models or transient heterologous expression systems are applied for electrophysiological investigations, each of these models having their limitations. The ability to create induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs), providing a source of human patient-specific cells, offers new opportunities in the field of cardiac disease modelling. Contemporary iPSC-CMs constitute the best possible in vitro model to study complex cardiac arrhythmia syndromes such as BrS. To date, thirteen reports on iPSC-CM models for BrS have been published and with this review we provide an overview of the current findings, with a focus on the electrophysiological parameters. We also discuss the methods that are used for cell derivation and data acquisition. In the end, we critically evaluate the knowledge gained by the use of these iPSC-CM models and discuss challenges and future perspectives for iPSC-CMs in the study of BrS and other arrhythmias.
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Pérez-Agustín A, Pinsach-Abuin M, Pagans S. Role of Non-Coding Variants in Brugada Syndrome. Int J Mol Sci 2020; 21:E8556. [PMID: 33202810 PMCID: PMC7698069 DOI: 10.3390/ijms21228556] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Revised: 11/09/2020] [Accepted: 11/10/2020] [Indexed: 12/15/2022] Open
Abstract
Brugada syndrome (BrS) is an inherited electrical heart disease associated with a high risk of sudden cardiac death (SCD). The genetic characterization of BrS has always been challenging. Although several cardiac ion channel genes have been associated with BrS, SCN5A is the only gene that presents definitive evidence for causality to be used for clinical diagnosis of BrS. However, more than 65% of diagnosed cases cannot be explained by variants in SCN5A or other genes. Therefore, in an important number of BrS cases, the underlying mechanisms are still elusive. Common variants, mostly located in non-coding regions, have emerged as potential modulators of the disease by affecting different regulatory mechanisms, including transcription factors (TFs), three-dimensional organization of the genome, or non-coding RNAs (ncRNAs). These common variants have been hypothesized to modulate the interindividual susceptibility of the disease, which could explain incomplete penetrance of BrS observed within families. Altogether, the study of both common and rare variants in parallel is becoming increasingly important to better understand the genetic basis underlying BrS. In this review, we aim to describe the challenges of studying non-coding variants associated with disease, re-examine the studies that have linked non-coding variants with BrS, and provide further evidence for the relevance of regulatory elements in understanding this cardiac disorder.
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Affiliation(s)
- Adrian Pérez-Agustín
- Department of Medical Sciences, School of Medicine, University of Girona, 17003 Girona, Spain;
- Biomedical Research Institute of Girona, 17190 Salt, Spain;
| | | | - Sara Pagans
- Department of Medical Sciences, School of Medicine, University of Girona, 17003 Girona, Spain;
- Biomedical Research Institute of Girona, 17190 Salt, Spain;
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6
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Jenewein T, Beckmann BM, Rose S, Osterhues HH, Schmidt U, Wolpert C, Miny P, Marschall C, Alders M, Bezzina CR, Wilde AAM, Kääb S, Kauferstein S. Genotype-phenotype dilemma in a case of sudden cardiac death with the E1053K mutation and a deletion in the SCN5A gene. Forensic Sci Int 2017; 275:187-194. [PMID: 28391114 DOI: 10.1016/j.forsciint.2017.02.038] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2016] [Revised: 01/13/2017] [Accepted: 02/23/2017] [Indexed: 12/19/2022]
Abstract
Mutations in the cardiac sodium channel gene SCN5A may result in various arrhythmia syndromes such as long QT syndrome type 3 (LQTS), Brugada syndrome (BrS), sick sinus syndrome (SSS), cardiac conduction diseases (CCD) and possibly dilated cardiomyopathy (DCM). In most of these inherited cardiac arrhythmia syndromes the phenotypical expression may range from asymptomatic phenotypes to sudden cardiac death (SCD). A 16-year-old female died during sleep. Autopsy did not reveal any explanation for her death and a genetic analysis was performed. A variant in the SCN5A gene (E1053K) that was previously described as disease causing was detected. Family members are carriers of the same E1053K variant, some even in a homozygous state, but surprisingly did not exhibit any pathological cardiac phenotype. Due to the lack of genotype-phenotype correlation further genetic studies were performed. A novel deletion in the promoter region of SCN5A was identified in the sudden death victim but was absent in other family members. These findings demonstrate the difficulties in interpreting the results of a family-based genetic screening and underline the phenotypic variability of SCN5A mutations.
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Affiliation(s)
- T Jenewein
- Institute of Legal Medicine, University of Frankfurt, Frankfurt am Main, Germany
| | - B M Beckmann
- University Hospital Munich, Department of Medicine I, Ludwig Maximilians University, Munich, Germany; German Cardiovascular Research Center (DZHK), Partner Site: Munich Heart Alliance, Munich, Germany
| | - S Rose
- Institute of Legal Medicine, University of Frankfurt, Frankfurt am Main, Germany
| | - H H Osterhues
- District Hospital Loerrach, Medical Clinic, Loerrach, Germany
| | - U Schmidt
- Institute of Legal Medicine, University Hospital of Freiburg, Freiburg, Germany
| | - C Wolpert
- Klinik für Innere Medizin, Cardiology Klinikum Ludwigsburg, Ludwigsburg, Germany
| | - P Miny
- Medical Genetics, University Hospital Basel, Basel, Switzerland
| | - C Marschall
- Center of Human Genetics and Laboratory Diagnostics, Martinsried, Germany
| | - M Alders
- Department of Clinical Genetics, Amsterdam Medical Center, Amsterdam, The Netherlands
| | - C R Bezzina
- Heart Centre, Department of Clinical and Experimental Cardiology, Amsterdam Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - A A M Wilde
- Heart Centre, Department of Clinical and Experimental Cardiology, Amsterdam Medical Center, University of Amsterdam, Amsterdam, The Netherlands; Princess Al-Jawhara Al-Brahim Centre of Excellence in Research of Hereditary Disorders, Jeddah, Kingdom of Saudi Arabia
| | - S Kääb
- University Hospital Munich, Department of Medicine I, Ludwig Maximilians University, Munich, Germany; German Cardiovascular Research Center (DZHK), Partner Site: Munich Heart Alliance, Munich, Germany
| | - S Kauferstein
- Institute of Legal Medicine, University of Frankfurt, Frankfurt am Main, Germany.
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7
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McKinnon D, Rosati B. Transmural gradients in ion channel and auxiliary subunit expression. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2016; 122:165-186. [PMID: 27702655 DOI: 10.1016/j.pbiomolbio.2016.09.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Accepted: 09/30/2016] [Indexed: 12/11/2022]
Abstract
Evolution has acted to shape the action potential in different regions of the heart in order to produce a maximally stable and efficient pump. This has been achieved by creating regional differences in ion channel expression levels within the heart as well as differences between equivalent cardiac tissues in different species. These region- and species-dependent differences in channel expression are established by regulatory evolution, evolution of the regulatory mechanisms that control channel expression levels. Ion channel auxiliary subunits are obvious targets for regulatory evolution, in order to change channel expression levels and/or modify channel function. This review focuses on the transmural gradients of ion channel expression in the heart and the role that regulation of auxiliary subunit expression plays in generating and shaping these gradients.
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Affiliation(s)
- David McKinnon
- Department of Veterans Affairs Medical Center, Northport, NY, USA; Institute of Molecular Cardiology, Stony Brook University, Stony Brook, NY, USA; Department of Neurobiology and Behavior, Stony Brook University, Stony Brook, NY, 11794, USA
| | - Barbara Rosati
- Department of Veterans Affairs Medical Center, Northport, NY, USA; Institute of Molecular Cardiology, Stony Brook University, Stony Brook, NY, USA; Department of Physiology and Biophysics, Stony Brook University, Stony Brook, NY, 11794, USA.
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8
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Yagihara N, Watanabe H, Barnett P, Duboscq-Bidot L, Thomas AC, Yang P, Ohno S, Hasegawa K, Kuwano R, Chatel S, Redon R, Schott JJ, Probst V, Koopmann TT, Bezzina CR, Wilde AAM, Nakano Y, Aiba T, Miyamoto Y, Kamakura S, Darbar D, Donahue BS, Shigemizu D, Tanaka T, Tsunoda T, Suda M, Sato A, Minamino T, Endo N, Shimizu W, Horie M, Roden DM, Makita N. Variants in the SCN5A Promoter Associated With Various Arrhythmia Phenotypes. J Am Heart Assoc 2016; 5:JAHA.116.003644. [PMID: 27625342 PMCID: PMC5079027 DOI: 10.1161/jaha.116.003644] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
BACKGROUND Mutations in the coding sequence of SCN5A, which encodes the cardiac Na(+) channel α subunit, have been associated with inherited susceptibility to various arrhythmias. Variable expression of SCN5A is a possible mechanism responsible for this pleiotropic effect; however, it is unknown whether variants in the promoter and regulatory regions of SCN5A also modulate the risk of arrhythmias. METHODS AND RESULTS We resequenced the core promoter region of SCN5A and the regulatory regions of SCN5A transcription in 1298 patients with arrhythmia phenotypes (atrial fibrillation, n=444; sinus node dysfunction, n=49; conduction disease, n=133; Brugada syndrome, n=583; and idiopathic ventricular fibrillation, n=89). We identified 26 novel rare variants in the SCN5A promoter in 29 patients affected by various arrhythmias (atrial fibrillation, n=6; sinus node dysfunction, n=1; conduction disease, n=3; Brugada syndrome, n=14; idiopathic ventricular fibrillation, n=5). The frequency of rare variants was higher in patients with arrhythmias than in controls. In the alignment with chromatin immunoprecipitation sequencing data, the majority of variants were located at regions bound by transcription factors. Using a luciferase reporter assay, 6 variants (Brugada syndrome, n=3; idiopathic ventricular fibrillation, n=2; conduction disease, n=1) were functionally characterized, and each displayed decreased promoter activity compared with the wild-type sequences. We also identified rare variants in the regulatory region that were associated with atrial fibrillation, and the variant decreased promoter activity. CONCLUSIONS Variants in the core promoter region and the transcription regulatory region of SCN5A were identified in multiple arrhythmia phenotypes, consistent with the idea that altered SCN5A transcription levels modulate susceptibility to arrhythmias.
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Affiliation(s)
- Nobue Yagihara
- Department of Cardiovascular Biology and Medicine, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Hiroshi Watanabe
- Department of Cardiovascular Biology and Medicine, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan Departments of Medicine and Pharmacology, Vanderbilt University School of Medicine, Nashville, TN
| | - Phil Barnett
- Department of Anatomy, Embryology and Physiology, Academic Medical Center, Amsterdam, The Netherlands
| | - Laetitia Duboscq-Bidot
- Institut National de la Santé et de la Recherche Médicale (INSERM) Unité Mixte de Recherche (UMR) 1087, L'Institut du Thorax, Nantes, France Centre National de la Recherche Scientifique (CNRS) UMR 6291, Nantes, France Université de Nantes, France Centre Hospitalier Universitaire (CHU) Nantes, Nantes, France
| | - Atack C Thomas
- Departments of Medicine and Pharmacology, Vanderbilt University School of Medicine, Nashville, TN
| | - Ping Yang
- Departments of Medicine and Pharmacology, Vanderbilt University School of Medicine, Nashville, TN
| | - Seiko Ohno
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science, Shiga, Japan
| | - Kanae Hasegawa
- Department of Cardiovascular Biology and Medicine, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Ryozo Kuwano
- Department of Molecular Genetics, Brain Research Institute, Niigata University, Niigata, Japan
| | - Stéphanie Chatel
- Institut National de la Santé et de la Recherche Médicale (INSERM) Unité Mixte de Recherche (UMR) 1087, L'Institut du Thorax, Nantes, France Centre National de la Recherche Scientifique (CNRS) UMR 6291, Nantes, France Université de Nantes, France Centre Hospitalier Universitaire (CHU) Nantes, Nantes, France
| | - Richard Redon
- Institut National de la Santé et de la Recherche Médicale (INSERM) Unité Mixte de Recherche (UMR) 1087, L'Institut du Thorax, Nantes, France Centre National de la Recherche Scientifique (CNRS) UMR 6291, Nantes, France Université de Nantes, France Centre Hospitalier Universitaire (CHU) Nantes, Nantes, France
| | - Jean-Jacques Schott
- Institut National de la Santé et de la Recherche Médicale (INSERM) Unité Mixte de Recherche (UMR) 1087, L'Institut du Thorax, Nantes, France Centre National de la Recherche Scientifique (CNRS) UMR 6291, Nantes, France Université de Nantes, France Centre Hospitalier Universitaire (CHU) Nantes, Nantes, France
| | - Vincent Probst
- Institut National de la Santé et de la Recherche Médicale (INSERM) Unité Mixte de Recherche (UMR) 1087, L'Institut du Thorax, Nantes, France Centre National de la Recherche Scientifique (CNRS) UMR 6291, Nantes, France Université de Nantes, France Centre Hospitalier Universitaire (CHU) Nantes, Nantes, France
| | - Tamara T Koopmann
- Department of Clinical and Experimental Cardiology, Academic Medical Center, Amsterdam, The Netherlands
| | - Connie R Bezzina
- Department of Clinical and Experimental Cardiology, Academic Medical Center, Amsterdam, The Netherlands
| | - Arthur A M Wilde
- Department of Clinical and Experimental Cardiology, Academic Medical Center, Amsterdam, The Netherlands Princess Al-Jawhara Al-Brahim Centre of Excellence in Research of Hereditary Disorders, Jeddah, Kingdom of Saudi Arabia
| | - Yukiko Nakano
- Division of Frontier Medical Science, Department of Cardiovascular Medicine, Programs for Biomedical Research, Graduate School of Biomedical Science, Hiroshima University, Hiroshima, Japan
| | - Takeshi Aiba
- Division of Arrhythmia and Electrophysiology, Department of Cardiovascular Medicine, National Cerebral and Cardiovascular Center, Suita, Japan
| | - Yoshihiro Miyamoto
- Division of Arrhythmia and Electrophysiology, Department of Cardiovascular Medicine, National Cerebral and Cardiovascular Center, Suita, Japan
| | - Shiro Kamakura
- Division of Arrhythmia and Electrophysiology, Department of Cardiovascular Medicine, National Cerebral and Cardiovascular Center, Suita, Japan
| | - Dawood Darbar
- Departments of Medicine and Pharmacology, Vanderbilt University School of Medicine, Nashville, TN University of Illinois at Chicago, IL
| | - Brian S Donahue
- Departments of Medicine and Pharmacology, Vanderbilt University School of Medicine, Nashville, TN
| | - Daichi Shigemizu
- Department of Medical Science Mathematics, Medical Research Institute, Tokyo Medical and Dental University, Tokyo, Japan Laboratory for Medical Science Mathematics, RIKEN Center for Integrative Medical Sciences, Yokohama, Japan
| | - Toshihiro Tanaka
- Department of Human Genetics and Disease Diversity, Tokyo Medical and Dental University, Tokyo, Japan
| | - Tatsuhiko Tsunoda
- Department of Medical Science Mathematics, Medical Research Institute, Tokyo Medical and Dental University, Tokyo, Japan Laboratory for Medical Science Mathematics, RIKEN Center for Integrative Medical Sciences, Yokohama, Japan
| | - Masayoshi Suda
- Department of Cardiovascular Biology and Medicine, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Akinori Sato
- Department of Cardiovascular Biology and Medicine, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Tohru Minamino
- Department of Cardiovascular Biology and Medicine, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Naoto Endo
- Division of Orthopedic Surgery, Brain Research Institute, Niigata University, Niigata, Japan Center for the Inter-organ Communication Research, Brain Research Institute, Niigata University, Niigata, Japan
| | - Wataru Shimizu
- Division of Arrhythmia and Electrophysiology, Department of Cardiovascular Medicine, National Cerebral and Cardiovascular Center, Suita, Japan Department of Cardiovascular Medicine, Nippon Medical School, Tokyo, Japan
| | - Minoru Horie
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science, Shiga, Japan
| | - Dan M Roden
- Departments of Medicine and Pharmacology, Vanderbilt University School of Medicine, Nashville, TN
| | - Naomasa Makita
- Department of Molecular Physiology, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan
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9
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Marcsa B, Dénes R, Vörös K, Rácz G, Sasvári-Székely M, Rónai Z, Törő K, Keszler G. A Common Polymorphism of the Human Cardiac Sodium Channel Alpha Subunit (SCN5A) Gene Is Associated with Sudden Cardiac Death in Chronic Ischemic Heart Disease. PLoS One 2015; 10:e0132137. [PMID: 26146998 PMCID: PMC4492622 DOI: 10.1371/journal.pone.0132137] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Accepted: 06/10/2015] [Indexed: 11/18/2022] Open
Abstract
Cardiac death remains one of the leading causes of mortality worldwide. Recent research has shed light on pathophysiological mechanisms underlying cardiac death, and several genetic variants in novel candidate genes have been identified as risk factors. However, the vast majority of studies performed so far investigated genetic associations with specific forms of cardiac death only (sudden, arrhythmogenic, ischemic etc.). The aim of the present investigation was to find a genetic marker that can be used as a general, powerful predictor of cardiac death risk. To this end, a case-control association study was performed on a heterogeneous cohort of cardiac death victims (n=360) and age-matched controls (n=300). Five single nucleotide polymorphisms (SNPs) from five candidate genes (beta2 adrenergic receptor, nitric oxide synthase 1 adaptor protein, ryanodine receptor 2, sodium channel type V alpha subunit and transforming growth factor-beta receptor 2) that had previously been shown to associate with certain forms of cardiac death were genotyped using sequence-specific real-time PCR probes. Logistic regression analysis revealed that the CC genotype of the rs11720524 polymorphism in the SCN5A gene encoding a subunit of the cardiac voltage-gated sodium channel occurred more frequently in the highly heterogeneous cardiac death cohort compared to the control population (p=0.019, odds ratio: 1.351). A detailed subgroup analysis uncovered that this effect was due to an association of this variant with cardiac death in chronic ischemic heart disease (p=0.012, odds ratio = 1.455). None of the other investigated polymorphisms showed association with cardiac death in this context. In conclusion, our results shed light on the role of this non-coding polymorphism in cardiac death in ischemic cardiomyopathy. Functional studies are needed to explore the pathophysiological background of this association.
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Affiliation(s)
- Boglárka Marcsa
- Department of Medical Chemistry, Molecular Biology and Pathobiochemistry, Semmelweis University, Budapest, Hungary
| | - Réka Dénes
- Department of Medical Chemistry, Molecular Biology and Pathobiochemistry, Semmelweis University, Budapest, Hungary
| | - Krisztina Vörös
- Department of Medical Chemistry, Molecular Biology and Pathobiochemistry, Semmelweis University, Budapest, Hungary
| | - Gergely Rácz
- 1st Department of Pathology and Experimental Cancer Research, Semmelweis University, Budapest, Hungary
| | - Mária Sasvári-Székely
- Department of Medical Chemistry, Molecular Biology and Pathobiochemistry, Semmelweis University, Budapest, Hungary
| | - Zsolt Rónai
- Department of Medical Chemistry, Molecular Biology and Pathobiochemistry, Semmelweis University, Budapest, Hungary
| | - Klára Törő
- Department of Forensic and Insurance Medicine, Semmelweis University, Budapest, Hungary
| | - Gergely Keszler
- Department of Medical Chemistry, Molecular Biology and Pathobiochemistry, Semmelweis University, Budapest, Hungary
- * E-mail:
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Novotný T, Raudenská M, Kadlecová J, Andršová I, Floriánová A, Vašků A, Kozák M, Sepši M, Křivan L, Gaillyová R, Špinar J. Mutation analysis of ion channel genes promoters in ventricular fibrillation survivors with coronary artery disease. COR ET VASA 2013. [DOI: 10.1016/j.crvasa.2013.06.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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11
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Jagu B, Charpentier F, Toumaniantz G. Identifying potential functional impact of mutations and polymorphisms: linking heart failure, increased risk of arrhythmias and sudden cardiac death. Front Physiol 2013; 4:254. [PMID: 24065925 PMCID: PMC3778269 DOI: 10.3389/fphys.2013.00254] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2013] [Accepted: 08/29/2013] [Indexed: 01/22/2023] Open
Abstract
Researchers and clinicians have discovered several important concepts regarding the mechanisms responsible for increased risk of arrhythmias, heart failure, and sudden cardiac death. One major step in defining the molecular basis of normal and abnormal cardiac electrical behavior has been the identification of single mutations that greatly increase the risk for arrhythmias and sudden cardiac death by changing channel-gating characteristics. Indeed, mutations in several genes encoding ion channels, such as SCN5A, which encodes the major cardiac Na+ channel, have emerged as the basis for a variety of inherited cardiac arrhythmias such as long QT syndrome, Brugada syndrome, progressive cardiac conduction disorder, sinus node dysfunction, or sudden infant death syndrome. In addition, genes encoding ion channel accessory proteins, like anchoring or chaperone proteins, which modify the expression, the regulation of endocytosis, and the degradation of ion channel a-subunits have also been reported as susceptibility genes for arrhythmic syndromes. The regulation of ion channel protein expression also depends on a fine-tuned balance among different other mechanisms, such as gene transcription, RNA processing, post-transcriptional control of gene expression by miRNA, protein synthesis, assembly and post-translational modification and trafficking. The aim of this review is to inventory, through the description of few representative examples, the role of these different biogenic mechanisms in arrhythmogenesis, HF and SCD in order to help the researcher to identify all the processes that could lead to arrhythmias. Identification of novel targets for drug intervention should result from further understanding of these fundamental mechanisms.
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Affiliation(s)
- Benoît Jagu
- INSERM, UMR1087, l'institut du thorax, IRS-UN Nantes, France ; CNRS, UMR6291 Nantes, France ; Faculté de Médecine, Université de Nantes Nantes, France
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Schroder EA, Lefta M, Zhang X, Bartos DC, Feng HZ, Zhao Y, Patwardhan A, Jin JP, Esser KA, Delisle BP. The cardiomyocyte molecular clock, regulation of Scn5a, and arrhythmia susceptibility. Am J Physiol Cell Physiol 2013; 304:C954-65. [PMID: 23364267 PMCID: PMC3651636 DOI: 10.1152/ajpcell.00383.2012] [Citation(s) in RCA: 106] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Accepted: 01/29/2013] [Indexed: 11/22/2022]
Abstract
The molecular clock mechanism underlies circadian rhythms and is defined by a transcription-translation feedback loop. Bmal1 encodes a core molecular clock transcription factor. Germline Bmal1 knockout mice show a loss of circadian variation in heart rate and blood pressure, and they develop dilated cardiomyopathy. We tested the role of the molecular clock in adult cardiomyocytes by generating mice that allow for the inducible cardiomyocyte-specific deletion of Bmal1 (iCSΔBmal1). ECG telemetry showed that cardiomyocyte-specific deletion of Bmal1 (iCSΔBmal1(-/-)) in adult mice slowed heart rate, prolonged RR and QRS intervals, and increased episodes of arrhythmia. Moreover, isolated iCSΔBmal1(-/-) hearts were more susceptible to arrhythmia during electromechanical stimulation. Examination of candidate cardiac ion channel genes showed that Scn5a, which encodes the principle cardiac voltage-gated Na(+) channel (Na(V)1.5), was circadianly expressed in control mouse and rat hearts but not in iCSΔBmal1(-/-) hearts. In vitro studies confirmed circadian expression of a human Scn5a promoter-luciferase reporter construct and determined that overexpression of clock factors transactivated the Scn5a promoter. Loss of Scn5a circadian expression in iCSΔBmal1(-/-) hearts was associated with decreased levels of Na(V)1.5 and Na(+) current in ventricular myocytes. We conclude that disruption of the molecular clock in the adult heart slows heart rate, increases arrhythmias, and decreases the functional expression of Scn5a. These findings suggest a potential link between environmental factors that alter the cardiomyocyte molecular clock and factors that influence arrhythmia susceptibility in humans.
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Bébarová M. Arrhythmogenesis in Brugada syndrome: impact and constrains of current concepts. Int J Cardiol 2013; 167:1760-71. [PMID: 23295036 DOI: 10.1016/j.ijcard.2012.12.019] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/04/2012] [Revised: 11/15/2012] [Accepted: 12/06/2012] [Indexed: 01/13/2023]
Abstract
Brugada syndrome (BrS), an inherited arrhythmogenic disease first described in 1992, is characterized by ST segment elevations on the electrocardiogram in the right precordium and by a high occurrence of arrhythmias including the life-threatening ventricular tachycardia/fibrillation. Knowledge of the underlying mechanisms of formation of arrhythmogenic substrate in BrS is essential, namely for the risk stratification of BrS patients and their therapy which is still restrained almost exclusively to the implantation of cardioverter/defibrillator. In spite of many crucial findings in this field published within recent years, the final consistent view has not been established so far. Hence, BrS described 20 years ago remains an actual topic of both clinical and experimental studies. This review presents an overview of the current knowledge related to the pathogenesis of BrS arrhythmogenic substrate, namely of the genetic basis of BrS, functional consequences of mutations related to BrS, and arrhythmogenic mechanisms in BrS.
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Affiliation(s)
- Markéta Bébarová
- Department of Physiology, Faculty of Medicine, Masaryk University, Kamenice 5, 625 00 Brno, Bohunice, Czech Republic.
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Giudicessi JR, Ackerman MJ. Determinants of incomplete penetrance and variable expressivity in heritable cardiac arrhythmia syndromes. Transl Res 2013; 161:1-14. [PMID: 22995932 PMCID: PMC3624763 DOI: 10.1016/j.trsl.2012.08.005] [Citation(s) in RCA: 125] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2012] [Accepted: 08/23/2012] [Indexed: 12/19/2022]
Abstract
Mutations in genes encoding ion channel pore-forming α-subunits and accessory β-subunits as well as intracellular calcium-handling proteins that collectively maintain the electromechanical function of the human heart serve as the underlying pathogenic substrate for a spectrum of sudden cardiac death (SCD)-predisposing heritable cardiac arrhythmia syndromes, including long QT syndrome (LQTS), short QT syndrome (SQTS), Brugada syndrome (BrS), and catecholaminergic polymorphic ventricular tachycardia (CPVT). Similar to many Mendelian disorders, the cardiac "channelopathies" exhibit incomplete penetrance, variable expressivity, and phenotypic overlap, whereby genotype-positive individuals within the same genetic lineage assume vastly different clinical courses as objectively assessed by phenotypic features such electrocardiographic abnormalities and number/type of cardiac events. In this Review, we summarize the current understanding of the global architecture of complex electrocardiographic traits such as the QT interval, focusing on the role of common genetic variants in the modulation of ECG parameters in health and the environmental and genetic determinants of incomplete penetrance and variable expressivity in the heritable cardiac arrhythmia syndromes most likely to be encountered in clinical practice.
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Polak S, Wiśniowska B, Glinka A, Polak M. Tox-database.net: a curated resource for data describing chemical triggered in vitro cardiac ion channels inhibition. BMC Pharmacol Toxicol 2012; 13:6. [PMID: 22947121 PMCID: PMC3506270 DOI: 10.1186/2050-6511-13-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2012] [Accepted: 08/13/2012] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND Drugs safety issues are now recognized as being factors generating the most reasons for drug withdrawals at various levels of development and at the post-approval stage. Among them cardiotoxicity remains the main reason, despite the substantial effort put into in vitro and in vivo testing, with the main focus put on hERG channel inhibition as the hypothesized surrogate of drug proarrhythmic potency. The large interest in the IKr current has resulted in the development of predictive tools and informative databases describing a drug's susceptibility to interactions with the hERG channel, although there are no similar, publicly available sets of data describing other ionic currents driven by the human cardiomyocyte ionic channels, which are recognized as an overlooked drug safety target. DISCUSSION The aim of this database development and publication was to provide a scientifically useful, easily usable and clearly verifiable set of information describing not only IKr (hERG), but also other human cardiomyocyte specific ionic channels inhibition data (IKs, INa, ICa). SUMMARY The broad range of data (chemical space and in vitro settings) and the easy to use user interface makes tox-database.net a useful tool for interested scientists. DATABASE URL: http://tox-database.net.
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Affiliation(s)
- Sebastian Polak
- Unit of Pharmacoepidemiology and Pharmacoeconomics, Faculty of Pharmacy Jagiellonian University Medical College, Medyczna 9 Street, 30-688 Krakow, Poland.
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Park JK, Martin LJ, Zhang X, Jegga AG, Benson DW. Genetic variants in SCN5A promoter are associated with arrhythmia phenotype severity in patients with heterozygous loss-of-function mutation. Heart Rhythm 2012; 9:1090-6. [PMID: 22370247 DOI: 10.1016/j.hrthm.2012.02.023] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2011] [Indexed: 12/20/2022]
Abstract
BACKGROUND Heterozygous SCN5A mutations have been associated with varied arrhythmia phenotypes; phenotype severity may range from asymptomatic electrocardiographic changes (mild phenotype) to symptomatic arrhythmias resulting in syncope, cardiac arrest, and sudden cardiac death (severe phenotype) even among family members carrying the same mutation. Risk-stratification schemes for SCN5A mutation carriers remain uncertain. OBJECTIVE To determine the role of SCN5A promoter variants and DNA methylation by using a family-based approach in predicting phenotype severity in a kindred with loss-of-function SCN5A mutation. METHODS In a large kindred with a heterozygous SCN5A loss-of-function mutation (1936delC, Q646RfsX5; 22 mutation carriers), we sought SCN5A promoter variants. In addition, we assessed SCN5A and genome-wide DNA methylation profiles on genomic DNA derived from blood (Illumina Human Methylation27 BeadChip). RESULTS During systematic survey of the 2.8-kb SCN5A promoter region, we identified 2 single nucleotide polymorphisms in complete linkage disequilibrium (rs41310749 and rs41310239). These promoter variants were significantly associated with disease severity (mild vs severe phenotype) (P = .0007), as all 3 patients with severe phenotype carried the 2-SNP variant on both mutant and wild-type alleles. Analysis did not support a role for the methylation of SCN5A-related genes. CONCLUSION These family-based genetic findings suggest that the presence of specific promoter variants increase the risk of a severe phenotype in heterozygous carriers of an SCN5A loss-of-function mutation.
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Affiliation(s)
- Ji Kwon Park
- Department of Obstetrics and Gynecology, and Institute of Health Sciences, School of Medicine, Gyeongsang National University, Jinju, Republic of Korea
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Atack TC, Stroud DM, Watanabe H, Yang T, Hall L, Hipkens SB, Lowe JS, Leake B, Magnuson MA, Yang P, Roden DM. Informatic and functional approaches to identifying a regulatory region for the cardiac sodium channel. Circ Res 2011; 109:38-46. [PMID: 21566215 DOI: 10.1161/circresaha.110.235630] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
RATIONALE Although multiple lines of evidence suggest that variable expression of the cardiac sodium channel gene SCN5A plays a role in susceptibility to arrhythmia, little is known about its transcriptional regulation. OBJECTIVE We used in silico and in vitro experiments to identify possible noncoding sequences important for transcriptional regulation of SCN5A. The results were extended to mice in which a putative regulatory region was deleted. METHODS AND RESULTS We identified 92 noncoding regions highly conserved (>70%) between human and mouse SCN5A orthologs. Three conserved noncoding sequences (CNS) showed significant (>5-fold) activity in luciferase assays. Further in vitro studies indicated one, CNS28 in intron 1, as a potential regulatory region. Using recombinase-mediated cassette exchange (RMCE), we generated mice in which a 435-base pair region encompassing CNS28 was removed. Animals homozygous for the deletion showed significant increases in SCN5A transcripts, Na(V)1.5 protein abundance, and sodium current measured in isolated ventricular myocytes. ECGs revealed a significantly shorter QRS (10.7±0.2 ms in controls versus 9.7±0.2 ms in knockouts), indicating more rapid ventricular conduction. In vitro analysis of CNS28 identified a short 3' segment within this region required for regulatory activity and including an E-box motif. Deletion of this segment reduced reporter activity to 3.6%±0.3% of baseline in CHO cells and 16%±3% in myocytes (both P<0.05), and mutation of individual sites in the E-box restored activity to 62%±4% and 57%±2% of baseline in CHO cells and myocytes, respectively (both P<0.05). CONCLUSIONS These findings establish that regulation of cardiac sodium channel expression modulates channel function in vivo, and identify a noncoding region underlying this regulation.
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Affiliation(s)
- Thomas C Atack
- Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN, USA
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Albert CM, MacRae CA, Chasman DI, VanDenburgh M, Buring JE, Manson JE, Cook NR, Newton-Cheh C. Common variants in cardiac ion channel genes are associated with sudden cardiac death. Circ Arrhythm Electrophysiol 2010; 3:222-9. [PMID: 20400777 DOI: 10.1161/circep.110.944934] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
BACKGROUND Rare variants in cardiac ion channel genes are associated with sudden cardiac death in rare primary arrhythmic syndromes; however, it is unknown whether common variation in these same genes may contribute to sudden cardiac death risk at the population level. METHODS AND RESULTS We examined the association between 147 single nucleotide polymorphisms (SNPs) (137 tag, 5 noncoding SNPs associated with QT interval duration, and 5 nonsynonymous SNPs) in 5 cardiac ion channel genes, KCNQ1, KCNH2, SCN5A, KCNE1, and KCNE2, and sudden and/or arrhythmic death in a combined nested case-control analysis among 516 cases and 1522 matched control subjects of European ancestry enrolled in 6 prospective cohort studies. After accounting for multiple testing, 2 SNPs (rs2283222 located in intron 11 in KCNQ1 and rs11720524 located in intron 1 in SCN5A) remained significantly associated with sudden/arrhythmic death (false discovery rate=0.01 and 0.03, respectively). Each increasing copy of the major T-allele of rs2283222 or the major C-allele of rs1172052 was associated with an odds ratio of 1.36 (95% confidence interval, 1.16 to 1.60; P=0.0002) and 1.30 (95% confidence interval, 1.12 to 1.51; P=0.0005), respectively. Control for cardiovascular risk factors and/or limiting the analysis to definite sudden cardiac death did not significantly alter these relationships. CONCLUSION In this combined analysis of 6 prospective cohort studies, 2 common intronic variants in KCNQ1 and SCN5A were associated with sudden cardiac death in individuals of European ancestry. Further study in other populations and investigation into the functional abnormalities associated with noncoding variation in these genes may lead to important insights into predisposition to lethal arrhythmias.
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Affiliation(s)
- Christine M Albert
- Center for Arrhythmia Prevention, Division of Preventive Medicine, Cardiovascular Division, Channing Laboratory, and Division of Aging, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115-1204, USA.
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Nakatome M, Yamamoto T, Isobe I, Matoba R. Diplotype analysis of the human cardiac sodium channel regulatory region in Japanese cases of sudden death by unknown causes. Leg Med (Tokyo) 2009; 11:298-301. [DOI: 10.1016/j.legalmed.2009.08.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2009] [Revised: 08/21/2009] [Accepted: 08/21/2009] [Indexed: 12/13/2022]
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Bush WS, Crawford DC, Alexander C, George AL, Roden DM, Ritchie MD. Genetic variation in the rhythmonome: ethnic variation and haplotype structure in candidate genes for arrhythmias. Pharmacogenomics 2009; 10:1043-53. [PMID: 19530973 DOI: 10.2217/pgs.09.67] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
AIMS The 'rhythmonome' is the term we have adopted to describe the set of genes that determine the normal coordinated electrical activity in the heart. Elements of this set include pore-forming ion channels, function-modifying proteins and intracellular calcium control elements. Rare mutations in many of these genes are known to cause unusual congenital monogenic arrhythmia syndromes, and single common variants have been reported to modify arrhythmia phenotypes. Here, we report an evaluation of the variation and haplotype structure in six key components of the rhythmonome. MATERIALS & METHODS SNPs were typed using DNA extracted from Coriell cell lines to survey allele frequencies and haplotype structure in six genes (ANK2, SCN5A, KCNE1 and 2 gene cluster, KCNQ1, KCNH2 and RYR2) across four human populations (African-American, European American, Han Chinese and Mexican American). RESULTS A total of 307 SNPs were analyzed across the six genes, revealing significant allele-frequency differences between populations and clear differences in haplotype structure. CONCLUSIONS The pattern of variation we report is an important step towards incorporating common variation across the rhythmonome in studies of arrhythmia susceptibility.
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Affiliation(s)
- William S Bush
- Center for Human Genetics Research & Department of Molecular Physiology & Biophysics, Vanderbilt University Medical Center, Nashville, TN, USA
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Abstract
The Brugada syndrome, first described as a new clinical entity in 1992, is widely recognized today as a form of inherited sudden cardiac arrest. The past 16 years witnessed a progressive increase in the number of reported cases and a dramatic proliferation of articles serving to define the clinical, genetic, cellular, ionic, and molecular aspects of the disease. This article provides a brief overview of recent advances in our understanding of the clinical presentation and molecular and cellular mechanisms and an update of existing controversies.
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SCN5A channelopathies--an update on mutations and mechanisms. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2008; 98:120-36. [PMID: 19027780 DOI: 10.1016/j.pbiomolbio.2008.10.005] [Citation(s) in RCA: 124] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Voltage-gated Na+ channels mediate the rapid upstroke of the action potential in excitable tissues. Na(v)1.5, encoded by the SCN5A gene, is the predominant isoform in the heart. Mutations in SCN5A are associated with distinct cardiac excitation disorders often resulting in life-threatening arrhythmias. This review outlines the currently known SCN5A mutations linked to three distinct cardiac rhythm disorders: long QT syndrome subtype 3 (LQT3), Brugada syndrome (BS), and cardiac conduction disease (CCD). Electrophysiological properties of the mutant channels are summarized and discussed in terms of Na+ channel structure-function relationships and regarding molecular mechanisms underlying the respective cardiac dysfunction. Possible reasons for less convincing genotype-phenotype correlations are suggested.
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Schulze-Bahr E. Susceptibility genes & modifiers for cardiac arrhythmias. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2008; 98:289-300. [DOI: 10.1016/j.pbiomolbio.2009.01.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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