1
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Lilliu E, Hackl B, Zabrodska E, Gewessler S, Karge T, Marksteiner J, Sauer J, Putz EM, Todt H, Hilber K, Koenig X. Cell size induced bias of current density in hypertrophic cardiomyocytes. Channels (Austin) 2024; 18:2361416. [PMID: 38836323 PMCID: PMC11155701 DOI: 10.1080/19336950.2024.2361416] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2024] [Accepted: 05/26/2024] [Indexed: 06/06/2024] Open
Abstract
Alterations in ion channel expression and function known as "electrical remodeling" contribute to the development of hypertrophy and to the emergence of arrhythmias and sudden cardiac death. However, comparing current density values - an electrophysiological parameter commonly utilized to assess ion channel function - between normal and hypertrophied cells may be flawed when current amplitude does not scale with cell size. Even more, common routines to study equally sized cells or to discard measurements when large currents do not allow proper voltage-clamp control may introduce a selection bias and thereby confound direct comparison. To test a possible dependence of current density on cell size and shape, we employed whole-cell patch-clamp recording of voltage-gated sodium and calcium currents in Langendorff-isolated ventricular cardiomyocytes and Purkinje myocytes, as well as in cardiomyocytes derived from trans-aortic constriction operated mice. Here, we describe a distinct inverse relationship between voltage-gated sodium and calcium current densities and cell capacitance both in normal and hypertrophied cells. This inverse relationship was well fit by an exponential function and may be due to physiological adaptations that do not scale proportionally with cell size or may be explained by a selection bias. Our study emphasizes the need to consider cell size bias when comparing current densities in cardiomyocytes of different sizes, particularly in hypertrophic cells. Conventional comparisons based solely on mean current density may be inadequate for groups with unequal cell size or non-proportional current amplitude and cell size scaling.
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Affiliation(s)
- Elena Lilliu
- Department of Neurophysiology and Neuropharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Benjamin Hackl
- Department of Neurophysiology and Neuropharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Eva Zabrodska
- Institute of Anatomy, First Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Stefanie Gewessler
- Department of Neurophysiology and Neuropharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Tobias Karge
- Ludwig Boltzmann Institute for Cardiovascular Research at the Center for Biomedical Research and Translational Surgery, Medical University of Vienna, Vienna, Austria
| | - Jessica Marksteiner
- Department of Neurophysiology and Neuropharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Jakob Sauer
- Department of Neurophysiology and Neuropharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Eva M. Putz
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Hannes Todt
- Department of Neurophysiology and Neuropharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Karlheinz Hilber
- Department of Neurophysiology and Neuropharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Xaver Koenig
- Department of Neurophysiology and Neuropharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
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2
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Marchal GA, Rivaud MR, Wolswinkel R, Basso C, van Veen TAB, Bezzina CR, Remme CA. Genetic background determines the severity of age-dependent cardiac structural abnormalities and arrhythmia susceptibility in Scn5a-1798insD mice. Europace 2024; 26:euae153. [PMID: 38875491 PMCID: PMC11203918 DOI: 10.1093/europace/euae153] [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: 02/09/2024] [Accepted: 05/12/2024] [Indexed: 06/16/2024] Open
Abstract
AIMS Patients with mutations in SCN5A encoding NaV1.5 often display variable severity of electrical and structural alterations, but the underlying mechanisms are not fully elucidated. We here investigate the combined modulatory effect of genetic background and age on disease severity in the Scn5a1798insD/+ mouse model. METHODS AND RESULTS In vivo electrocardiogram and echocardiograms, ex vivo electrical and optical mapping, and histological analyses were performed in adult (2-7 months) and aged (8-28 months) wild-type (WT) and Scn5a1798insD/+ (mutant, MUT) mice from the FVB/N and 129P2 inbred strains. Atrio-ventricular (AV) conduction, ventricular conduction, and ventricular repolarization are modulated by strain, genotype, and age. An aging effect was present in MUT mice, with aged MUT mice of both strains showing prolonged QRS interval and right ventricular (RV) conduction slowing. 129P2-MUT mice were severely affected, with adult and aged 129P2-MUT mice displaying AV and ventricular conduction slowing, prolonged repolarization, and spontaneous arrhythmias. In addition, the 129P2 strain appeared particularly susceptible to age-dependent electrical, functional, and structural alterations including RV conduction slowing, reduced left ventricular (LV) ejection fraction, RV dilatation, and myocardial fibrosis as compared to FVB/N mice. Overall, aged 129P2-MUT mice displayed the most severe conduction defects, RV dilatation, and myocardial fibrosis, in addition to the highest frequency of spontaneous arrhythmia and inducible arrhythmias. CONCLUSION Genetic background and age both modulate disease severity in Scn5a1798insD/+ mice and hence may explain, at least in part, the variable disease expressivity observed in patients with SCN5A mutations. Age- and genetic background-dependent development of cardiac structural alterations furthermore impacts arrhythmia risk. Our findings therefore emphasize the importance of continued assessment of cardiac structure and function in patients carrying SCN5A mutations.
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Affiliation(s)
- Gerard A Marchal
- Department of Experimental Cardiology, Heart Centre, Amsterdam UMC location University of Amsterdam, Meibergdreef 15, PO Box 22660, 1100 DD Amsterdam, The Netherlands
- Amsterdam Cardiovascular Sciences, Heart Failure & Arrhythmias, Meibergdreef 15, PO Box 22660, 1100 DD Amsterdam, The Netherlands
- OptoCARD Lab, Institute of Clinical Physiology (IFC-CNR), Florence, Italy
| | - Mathilde R Rivaud
- Department of Experimental Cardiology, Heart Centre, Amsterdam UMC location University of Amsterdam, Meibergdreef 15, PO Box 22660, 1100 DD Amsterdam, The Netherlands
- Amsterdam Cardiovascular Sciences, Heart Failure & Arrhythmias, Meibergdreef 15, PO Box 22660, 1100 DD Amsterdam, The Netherlands
| | - Rianne Wolswinkel
- Department of Experimental Cardiology, Heart Centre, Amsterdam UMC location University of Amsterdam, Meibergdreef 15, PO Box 22660, 1100 DD Amsterdam, The Netherlands
- Amsterdam Cardiovascular Sciences, Heart Failure & Arrhythmias, Meibergdreef 15, PO Box 22660, 1100 DD Amsterdam, The Netherlands
| | - Cristina Basso
- Department of Cardiac, Thoracic and Vascular Sciences and Public Health, University of Padova, Padua, Italy
| | - Toon A B van Veen
- Department of Medical Physiology, Division Heart & Lungs, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Connie R Bezzina
- Department of Experimental Cardiology, Heart Centre, Amsterdam UMC location University of Amsterdam, Meibergdreef 15, PO Box 22660, 1100 DD Amsterdam, The Netherlands
- Amsterdam Cardiovascular Sciences, Heart Failure & Arrhythmias, Meibergdreef 15, PO Box 22660, 1100 DD Amsterdam, The Netherlands
| | - Carol Ann Remme
- Department of Experimental Cardiology, Heart Centre, Amsterdam UMC location University of Amsterdam, Meibergdreef 15, PO Box 22660, 1100 DD Amsterdam, The Netherlands
- Amsterdam Cardiovascular Sciences, Heart Failure & Arrhythmias, Meibergdreef 15, PO Box 22660, 1100 DD Amsterdam, The Netherlands
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3
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Proost VM, van den Berg MP, Remme CA, Wilde AAM. SCN5A-1795insD founder variant: a unique Dutch experience spanning 7 decades. Neth Heart J 2023:10.1007/s12471-023-01799-8. [PMID: 37474841 PMCID: PMC10400486 DOI: 10.1007/s12471-023-01799-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/05/2023] [Indexed: 07/22/2023] Open
Abstract
The SCN5A-1795insD founder variant is a unique SCN5A gene variant found in a large Dutch pedigree that first came to attention in the late 1950s. To date, this is still one of the largest and best described SCN5A founder families worldwide. It was the first time that a single pathogenic variant in SCN5A proved to be sufficient to cause a sodium channel overlap syndrome. Affected family members displayed features of Brugada syndrome, cardiac conduction disease and long QT syndrome type 3, thus encompassing features of both loss and gain of sodium channel function. This brief summary takes us past 70 years of clinical experience and over 2 decades of research. It is remarkable to what extent researchers and clinicians have managed to gain understanding of this complex phenotype in a relatively short time. Extensive clinical, genetic, electrophysiological and molecular studies have provided fundamental insights into SCN5A and the cardiac sodium channel Nav1.5.
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Affiliation(s)
- Virginnio M Proost
- Department of Clinical Cardiology, Heart Centre, Amsterdam Cardiovascular Sciences, Heart Failure & Arrhythmias, Amsterdam University Medical Centres, location Academic Medical Centre/University of Amsterdam, Amsterdam, The Netherlands
| | - Maarten P van den Berg
- Department of Cardiology, University Medical Centre Groningen, University of Groningen, Groningen, The Netherlands
| | - Carol Ann Remme
- Department of Experimental Cardiology, Heart Centre, Amsterdam Cardiovascular Sciences, Heart Failure & Arrhythmias, Amsterdam University Medical Centres, location Academic Medical Centre/University of Amsterdam, Amsterdam, The Netherlands
| | - Arthur A M Wilde
- Department of Clinical Cardiology, Heart Centre, Amsterdam Cardiovascular Sciences, Heart Failure & Arrhythmias, Amsterdam University Medical Centres, location Academic Medical Centre/University of Amsterdam, Amsterdam, The Netherlands.
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4
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Ripplinger CM, Glukhov AV, Kay MW, Boukens BJ, Chiamvimonvat N, Delisle BP, Fabritz L, Hund TJ, Knollmann BC, Li N, Murray KT, Poelzing S, Quinn TA, Remme CA, Rentschler SL, Rose RA, Posnack NG. Guidelines for assessment of cardiac electrophysiology and arrhythmias in small animals. Am J Physiol Heart Circ Physiol 2022; 323:H1137-H1166. [PMID: 36269644 PMCID: PMC9678409 DOI: 10.1152/ajpheart.00439.2022] [Citation(s) in RCA: 32] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Revised: 10/11/2022] [Accepted: 10/17/2022] [Indexed: 01/09/2023]
Abstract
Cardiac arrhythmias are a major cause of morbidity and mortality worldwide. Although recent advances in cell-based models, including human-induced pluripotent stem cell-derived cardiomyocytes (iPSC-CM), are contributing to our understanding of electrophysiology and arrhythmia mechanisms, preclinical animal studies of cardiovascular disease remain a mainstay. Over the past several decades, animal models of cardiovascular disease have advanced our understanding of pathological remodeling, arrhythmia mechanisms, and drug effects and have led to major improvements in pacing and defibrillation therapies. There exist a variety of methodological approaches for the assessment of cardiac electrophysiology and a plethora of parameters may be assessed with each approach. This guidelines article will provide an overview of the strengths and limitations of several common techniques used to assess electrophysiology and arrhythmia mechanisms at the whole animal, whole heart, and tissue level with a focus on small animal models. We also define key electrophysiological parameters that should be assessed, along with their physiological underpinnings, and the best methods with which to assess these parameters.
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Affiliation(s)
- Crystal M Ripplinger
- Department of Pharmacology, University of California Davis School of Medicine, Davis, California
| | - Alexey V Glukhov
- Department of Medicine, Cardiovascular Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin
| | - Matthew W Kay
- Department of Biomedical Engineering, The George Washington University, Washington, District of Columbia
| | - Bastiaan J Boukens
- Department Physiology, University Maastricht, Maastricht University Medical Center, Maastricht, The Netherlands
- Department of Medical Biology, University of Amsterdam, Amsterdam University Medical Center, Amsterdam, The Netherlands
| | - Nipavan Chiamvimonvat
- Department of Pharmacology, University of California Davis School of Medicine, Davis, California
- Department of Internal Medicine, University of California Davis School of Medicine, Davis, California
- Veterans Affairs Northern California Healthcare System, Mather, California
| | - Brian P Delisle
- Department of Physiology, University of Kentucky, Lexington, Kentucky
| | - Larissa Fabritz
- University Center of Cardiovascular Science, University Heart and Vascular Center, University Hospital Hamburg-Eppendorf with DZHK Hamburg/Kiel/Luebeck, Germany
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Thomas J Hund
- Department of Internal Medicine, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, Ohio
- Department of Biomedical Engineering, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, Ohio
| | - Bjorn C Knollmann
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Na Li
- Department of Medicine, Baylor College of Medicine, Houston, Texas
| | - Katherine T Murray
- Departments of Medicine and Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Steven Poelzing
- Virginia Tech Carilon School of Medicine, Center for Heart and Reparative Medicine Research, Fralin Biomedical Research Institute at Virginia Tech, Roanoke, Virginia
- Department of Biomedical Engineering and Mechanics, Virginia Polytechnic Institute and State University, Blacksburg, Virginia
| | - T Alexander Quinn
- Department of Physiology and Biophysics, Dalhousie University, Halifax, Nova Scotia, Canada
- School of Biomedical Engineering, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Carol Ann Remme
- Department of Experimental Cardiology, Heart Centre, Amsterdam Cardiovascular Sciences, Heart Failure and Arrhythmias Amsterdam UMC Location University of Amsterdam, Amsterdam, The Netherlands
| | - Stacey L Rentschler
- Cardiovascular Division, Department of Medicine, Washington University in Saint Louis, School of Medicine, Saint Louis, Missouri
| | - Robert A Rose
- Department of Cardiac Sciences, Libin Cardiovascular Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
- Department of Physiology and Pharmacology, Libin Cardiovascular Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Nikki G Posnack
- Sheikh Zayed Institute for Pediatric Surgical Innovation, Children's National Hospital, Washington, District of Columbia
- Department of Pediatrics, George Washington University School of Medicine, Washington, District of Columbia
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5
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SCN5A mutation in Brugada syndrome is associated with substrate severity detected by ECG imaging and high density electroanatomical mapping. Heart Rhythm 2022; 19:945-951. [DOI: 10.1016/j.hrthm.2022.01.034] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Revised: 01/25/2022] [Accepted: 01/28/2022] [Indexed: 11/16/2022]
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6
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Obergassel J, O'Reilly M, Sommerfeld LC, Kabir SN, O'Shea C, Syeda F, Eckardt L, Kirchhof P, Fabritz L. Effects of genetic background, sex, and age on murine atrial electrophysiology. Europace 2021; 23:958-969. [PMID: 33462602 DOI: 10.1093/europace/euaa369] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Indexed: 11/14/2022] Open
Abstract
AIMS Genetically altered mice are powerful models to investigate mechanisms of atrial arrhythmias, but normal ranges for murine atrial electrophysiology have not been robustly characterized. METHODS AND RESULTS We analyzed results from 221 electrophysiological (EP) studies in isolated, Langendorff-perfused hearts of wildtype mice (114 female, 107 male) from 2.5 to 17.7 months (mean 7 months) with different genetic backgrounds (C57BL/6, FVB/N, MF1, 129/Sv, Swiss agouti). Left atrial monophasic action potential duration (LA-APD), interatrial activation time (IA-AT), and atrial effective refractory period (ERP) were summarized at different pacing cycle lengths (PCLs). Factors influencing atrial electrophysiology including genetic background, sex, and age were determined. LA-APD70 was 18 ± 0.5 ms, atrial ERP was 27 ± 0.8 ms, and IA-AT was 17 ± 0.5 ms at 100 ms PCL. LA-APD was longer with longer PCL (+17% from 80 to 120 ms PCL for APD70), while IA-AT decreased (-7% from 80 to 120 ms PCL). Female sex was associated with longer ERP (+14% vs. males). Genetic background influenced atrial electrophysiology: LA-APD70 (-20% vs. average) and atrial ERP (-25% vs. average) were shorter in Swiss agouti background compared to others. LA-APD70 (+25% vs. average) and IA-AT (+44% vs. average) were longer in 129/Sv mice. Atrial ERP was longer in FVB/N (+34% vs. average) and in younger experimental groups below 6 months of age. CONCLUSION This work defines normal ranges for murine atrial EP parameters. Genetic background has a profound effect on these parameters, at least of the magnitude as those of sex and age. These results can inform the experimental design and interpretation of murine atrial electrophysiology.
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Affiliation(s)
- Julius Obergassel
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, UK.,University Heart and Vascular Center, University Hospital Hamburg-Eppendorf, Hamburg, Germany
| | - Molly O'Reilly
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, UK
| | - Laura C Sommerfeld
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, UK
| | - S Nashitha Kabir
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, UK
| | - Christopher O'Shea
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, UK
| | - Fahima Syeda
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, UK
| | - Lars Eckardt
- Department of Cardiology II - Electrophysiology, University Hospital Münster, Münster, Germany
| | - Paulus Kirchhof
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, UK.,University Heart and Vascular Center, University Hospital Hamburg-Eppendorf, Hamburg, Germany.,Department of Cardiology, UHB NHS Trust, Birmingham, UK.,Department of Cardiology, SWBH NHS Trust, Birmingham City Hospital, Birmingham, UK.,German Center for Cardiovascular Research, Partner Site Hamburg/Kiel/Lübeck, Hamburg, Germany
| | - Larissa Fabritz
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, UK.,University Heart and Vascular Center, University Hospital Hamburg-Eppendorf, Hamburg, Germany.,Department of Cardiology, UHB NHS Trust, Birmingham, UK
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7
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Odening KE, Gomez AM, Dobrev D, Fabritz L, Heinzel FR, Mangoni ME, Molina CE, Sacconi L, Smith G, Stengl M, Thomas D, Zaza A, Remme CA, Heijman J. ESC working group on cardiac cellular electrophysiology position paper: relevance, opportunities, and limitations of experimental models for cardiac electrophysiology research. Europace 2021; 23:1795-1814. [PMID: 34313298 DOI: 10.1093/europace/euab142] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2021] [Accepted: 05/19/2021] [Indexed: 12/19/2022] Open
Abstract
Cardiac arrhythmias are a major cause of death and disability. A large number of experimental cell and animal models have been developed to study arrhythmogenic diseases. These models have provided important insights into the underlying arrhythmia mechanisms and translational options for their therapeutic management. This position paper from the ESC Working Group on Cardiac Cellular Electrophysiology provides an overview of (i) currently available in vitro, ex vivo, and in vivo electrophysiological research methodologies, (ii) the most commonly used experimental (cellular and animal) models for cardiac arrhythmias including relevant species differences, (iii) the use of human cardiac tissue, induced pluripotent stem cell (hiPSC)-derived and in silico models to study cardiac arrhythmias, and (iv) the availability, relevance, limitations, and opportunities of these cellular and animal models to recapitulate specific acquired and inherited arrhythmogenic diseases, including atrial fibrillation, heart failure, cardiomyopathy, myocarditis, sinus node, and conduction disorders and channelopathies. By promoting a better understanding of these models and their limitations, this position paper aims to improve the quality of basic research in cardiac electrophysiology, with the ultimate goal to facilitate the clinical translation and application of basic electrophysiological research findings on arrhythmia mechanisms and therapies.
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Affiliation(s)
- Katja E Odening
- Translational Cardiology, Department of Cardiology, Inselspital, Bern University Hospital, Bern, Switzerland.,Institute of Physiology, University of Bern, Bern, Switzerland
| | - Ana-Maria Gomez
- Signaling and cardiovascular pathophysiology-UMR-S 1180, Inserm, Université Paris-Saclay, 92296 Châtenay-Malabry, France
| | - Dobromir Dobrev
- Institute of Pharmacology, West German Heart and Vascular Center, University Duisburg-Essen, Essen, Germany
| | - Larissa Fabritz
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, UK.,Department of Cardiology, University Hospital Birmingham NHS Trust, Birmingham, UK
| | - Frank R Heinzel
- Department of Internal Medicine and Cardiology, Charité - Universitätsmedizin Berlin, Campus Virchow-Klinikum, Berlin, Germany.,DZHK (German Centre for Cardiovascular Research), Partner Site, Berlin, Germany
| | - Matteo E Mangoni
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France
| | - Cristina E Molina
- Institute of Experimental Cardiovascular Research, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.,German Centre for Cardiovascular Research (DZHK), Partner Site, Hamburg/Kiel/Lübeck, Germany
| | - Leonardo Sacconi
- National Institute of Optics and European Laboratory for Non Linear Spectroscopy, Italy.,Institute for Experimental Cardiovascular Medicine, University Freiburg, Germany
| | - Godfrey Smith
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, UK
| | - Milan Stengl
- Department of Physiology, Faculty of Medicine in Pilsen, Charles University, Pilsen, Czech Republic
| | - Dierk Thomas
- Department of Cardiology, University Hospital Heidelberg, Heidelberg, Germany; Heidelberg Center for Heart Rhythm Disorders (HCR), University Hospital Heidelberg, Heidelberg, Germany.,German Centre for Cardiovascular Research (DZHK), Partner Site, Heidelberg/Mannheim, Germany
| | - Antonio Zaza
- Department of Biotechnology and Bioscience, University of Milano-Bicocca, Milano, Italy
| | - Carol Ann Remme
- Department of Experimental Cardiology, Amsterdam UMC, location AMC, Amsterdam, The Netherlands
| | - Jordi Heijman
- Department of Cardiology, CARIM School for Cardiovascular Diseases, Maastricht University, Maastricht, The Netherlands
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8
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Marchal GA, Jouni M, Chiang DY, Pérez-Hernández M, Podliesna S, Yu N, Casini S, Potet F, Veerman CC, Klerk M, Lodder EM, Mengarelli I, Guan K, Vanoye CG, Rothenberg E, Charpentier F, Redon R, George AL, Verkerk AO, Bezzina CR, MacRae CA, Burridge PW, Delmar M, Galjart N, Portero V, Remme CA. Targeting the Microtubule EB1-CLASP2 Complex Modulates Na V1.5 at Intercalated Discs. Circ Res 2021; 129:349-365. [PMID: 34092082 PMCID: PMC8298292 DOI: 10.1161/circresaha.120.318643] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
[Figure: see text].
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Affiliation(s)
- Gerard A Marchal
- Department of Experimental Cardiology, Amsterdam UMC - location AMC, The Netherlands (G.A.M., S.P., S.C., C.C.V., E.M.L., I.M., A.O.V., C.R.B., V.P., C.A.R.)
| | - Mariam Jouni
- Department of Pharmacology, University Feinberg School of Medicine, Chicago, IL (M.J., F.P., C.G.V., A.L.G., P.W.B.)
| | - David Y Chiang
- Brigham and Women's Hospital and Harvard Medical School, Boston, MA (D.Y.C., C.A.M.)
| | | | - Svitlana Podliesna
- Department of Experimental Cardiology, Amsterdam UMC - location AMC, The Netherlands (G.A.M., S.P., S.C., C.C.V., E.M.L., I.M., A.O.V., C.R.B., V.P., C.A.R.)
| | - Nuo Yu
- Department of Cell Biology, Erasmus Medical Centre Rotterdam, The Netherlands (N.Y., N.G.)
| | - Simona Casini
- Department of Experimental Cardiology, Amsterdam UMC - location AMC, The Netherlands (G.A.M., S.P., S.C., C.C.V., E.M.L., I.M., A.O.V., C.R.B., V.P., C.A.R.)
| | - Franck Potet
- Department of Pharmacology, University Feinberg School of Medicine, Chicago, IL (M.J., F.P., C.G.V., A.L.G., P.W.B.)
| | - Christiaan C Veerman
- Department of Experimental Cardiology, Amsterdam UMC - location AMC, The Netherlands (G.A.M., S.P., S.C., C.C.V., E.M.L., I.M., A.O.V., C.R.B., V.P., C.A.R.)
| | - Mischa Klerk
- Department of Medical Biology, Amsterdam UMC - location AMC, The Netherlands (M.K., A.O.V.)
| | - Elisabeth M Lodder
- Department of Experimental Cardiology, Amsterdam UMC - location AMC, The Netherlands (G.A.M., S.P., S.C., C.C.V., E.M.L., I.M., A.O.V., C.R.B., V.P., C.A.R.)
| | - Isabella Mengarelli
- Department of Experimental Cardiology, Amsterdam UMC - location AMC, The Netherlands (G.A.M., S.P., S.C., C.C.V., E.M.L., I.M., A.O.V., C.R.B., V.P., C.A.R.)
| | - Kaomei Guan
- Institute of Pharmacology and Toxicology, Technische Universität Dresden, Germany (K.G.)
| | - Carlos G Vanoye
- Department of Pharmacology, University Feinberg School of Medicine, Chicago, IL (M.J., F.P., C.G.V., A.L.G., P.W.B.)
| | - Eli Rothenberg
- Department of Biochemistry and Pharmacology (E.R.), NYU School of Medicine
| | - Flavien Charpentier
- Université de Nantes, CNRS, INSERM, l'institut du Thorax, Nantes, France (F.C., R.R., V.P.)
| | - Richard Redon
- Université de Nantes, CNRS, INSERM, l'institut du Thorax, Nantes, France (F.C., R.R., V.P.)
| | - Alfred L George
- Department of Pharmacology, University Feinberg School of Medicine, Chicago, IL (M.J., F.P., C.G.V., A.L.G., P.W.B.)
| | - Arie O Verkerk
- Department of Experimental Cardiology, Amsterdam UMC - location AMC, The Netherlands (G.A.M., S.P., S.C., C.C.V., E.M.L., I.M., A.O.V., C.R.B., V.P., C.A.R.)
- Department of Medical Biology, Amsterdam UMC - location AMC, The Netherlands (M.K., A.O.V.)
| | - Connie R Bezzina
- Department of Experimental Cardiology, Amsterdam UMC - location AMC, The Netherlands (G.A.M., S.P., S.C., C.C.V., E.M.L., I.M., A.O.V., C.R.B., V.P., C.A.R.)
| | - Calum A MacRae
- Brigham and Women's Hospital and Harvard Medical School, Boston, MA (D.Y.C., C.A.M.)
| | - Paul W Burridge
- Department of Pharmacology, University Feinberg School of Medicine, Chicago, IL (M.J., F.P., C.G.V., A.L.G., P.W.B.)
| | - Mario Delmar
- Division of Cardiology (M.P.-H., M.D.), NYU School of Medicine
| | - Niels Galjart
- Department of Cell Biology, Erasmus Medical Centre Rotterdam, The Netherlands (N.Y., N.G.)
| | - Vincent Portero
- Department of Experimental Cardiology, Amsterdam UMC - location AMC, The Netherlands (G.A.M., S.P., S.C., C.C.V., E.M.L., I.M., A.O.V., C.R.B., V.P., C.A.R.)
- Université de Nantes, CNRS, INSERM, l'institut du Thorax, Nantes, France (F.C., R.R., V.P.)
| | - Carol Ann Remme
- Department of Experimental Cardiology, Amsterdam UMC - location AMC, The Netherlands (G.A.M., S.P., S.C., C.C.V., E.M.L., I.M., A.O.V., C.R.B., V.P., C.A.R.)
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9
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Schroder EA, Wayland JL, Samuels KM, Shah SF, Burgess DE, Seward T, Elayi CS, Esser KA, Delisle BP. Cardiomyocyte Deletion of Bmal1 Exacerbates QT- and RR-Interval Prolongation in Scn5a +/ΔKPQ Mice. Front Physiol 2021; 12:681011. [PMID: 34248669 PMCID: PMC8265216 DOI: 10.3389/fphys.2021.681011] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Accepted: 05/18/2021] [Indexed: 11/21/2022] Open
Abstract
Circadian rhythms are generated by cell autonomous circadian clocks that perform a ubiquitous cellular time-keeping function and cell type-specific functions important for normal physiology. Studies show inducing the deletion of the core circadian clock transcription factor Bmal1 in adult mouse cardiomyocytes disrupts cardiac circadian clock function, cardiac ion channel expression, slows heart rate, and prolongs the QT-interval at slow heart rates. This study determined how inducing the deletion of Bmal1 in adult cardiomyocytes impacted the in vivo electrophysiological phenotype of a knock-in mouse model for the arrhythmogenic long QT syndrome (Scn5a+/ΔKPQ). Electrocardiographic telemetry showed inducing the deletion of Bmal1 in the cardiomyocytes of mice with or without the ΔKPQ-Scn5a mutation increased the QT-interval at RR-intervals that were ≥130 ms. Inducing the deletion of Bmal1 in the cardiomyocytes of mice with or without the ΔKPQ-Scn5a mutation also increased the day/night rhythm-adjusted mean in the RR-interval, but it did not change the period, phase or amplitude. Compared to mice without the ΔKPQ-Scn5a mutation, mice with the ΔKPQ-Scn5a mutation had reduced heart rate variability (HRV) during the peak of the day/night rhythm in the RR-interval. Inducing the deletion of Bmal1 in cardiomyocytes did not affect HRV in mice without the ΔKPQ-Scn5a mutation, but it did increase HRV in mice with the ΔKPQ-Scn5a mutation. The data demonstrate that deleting Bmal1 in cardiomyocytes exacerbates QT- and RR-interval prolongation in mice with the ΔKPQ-Scn5a mutation.
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Affiliation(s)
- Elizabeth A Schroder
- Department of Physiology, University of Kentucky, Lexington, KY, United States.,Internal Medicine and Pulmonary, University of Kentucky, Lexington, KY, United States
| | - Jennifer L Wayland
- Department of Physiology, University of Kentucky, Lexington, KY, United States
| | - Kaitlyn M Samuels
- Department of Physiology, University of Kentucky, Lexington, KY, United States
| | - Syed F Shah
- Department of Physiology, University of Kentucky, Lexington, KY, United States
| | - Don E Burgess
- Department of Physiology, University of Kentucky, Lexington, KY, United States
| | - Tanya Seward
- Department of Physiology, University of Kentucky, Lexington, KY, United States
| | | | - Karyn A Esser
- Department of Physiology and Functional Genomics, University of Florida, Gainesville, FL, United States
| | - Brian P Delisle
- Department of Physiology, University of Kentucky, Lexington, KY, United States
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10
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Rivaud MR, Marchal GA, Wolswinkel R, Jansen JA, van der Made I, Beekman L, Ruiz-Villalba A, Baartscheer A, Rajamani S, Belardinelli L, van Veen TAB, Basso C, Thiene G, Creemers EE, Bezzina CR, Remme CA. Functional modulation of atrio-ventricular conduction by enhanced late sodium current and calcium-dependent mechanisms in Scn5a1798insD/+ mice. Europace 2021; 22:1579-1589. [PMID: 32778883 PMCID: PMC7544532 DOI: 10.1093/europace/euaa127] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Accepted: 05/01/2020] [Indexed: 11/16/2022] Open
Abstract
Aims SCN5A mutations are associated with arrhythmia syndromes, including Brugada syndrome, long QT syndrome type 3 (LQT3), and cardiac conduction disease. Long QT syndrome type 3 patients display atrio-ventricular (AV) conduction slowing which may contribute to arrhythmogenesis. We here investigated the as yet unknown underlying mechanisms. Methods and results We assessed electrophysiological and molecular alterations underlying AV-conduction abnormalities in mice carrying the Scn5a1798insD/+ mutation. Langendorff-perfused Scn5a1798insD/+ hearts showed prolonged AV-conduction compared to wild type (WT) without changes in atrial and His-ventricular (HV) conduction. The late sodium current (INa,L) inhibitor ranolazine (RAN) normalized AV-conduction in Scn5a1798insD/+ mice, likely by preventing the mutation-induced increase in intracellular sodium ([Na+]i) and calcium ([Ca2+]i) concentrations. Indeed, further enhancement of [Na+]i and [Ca2+]i by the Na+/K+-ATPase inhibitor ouabain caused excessive increase in AV-conduction time in Scn5a1798insD/+ hearts. Scn5a1798insD/+ mice from the 129P2 strain displayed more severe AV-conduction abnormalities than FVB/N-Scn5a1798insD/+ mice, in line with their larger mutation-induced INa,L. Transverse aortic constriction (TAC) caused excessive prolongation of AV-conduction in FVB/N-Scn5a1798insD/+ mice (while HV-intervals remained unchanged), which was prevented by chronic RAN treatment. Scn5a1798insD/+-TAC hearts showed decreased mRNA levels of conduction genes in the AV-nodal region, but no structural changes in the AV-node or His bundle. In Scn5a1798insD/+-TAC mice deficient for the transcription factor Nfatc2 (effector of the calcium-calcineurin pathway), AV-conduction and conduction gene expression were restored to WT levels. Conclusions Our findings indicate a detrimental role for enhanced INa,L and consequent calcium dysregulation on AV-conduction in Scn5a1798insD/+ mice, providing evidence for a functional mechanism underlying AV-conduction disturbances secondary to gain-of-function SCN5A mutations.
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Affiliation(s)
- Mathilde R Rivaud
- Department of Clinical and Experimental Cardiology, Amsterdam UMC, Heart Center, Academic Medical Center, Room K2-104.2, Meibergdreef 15, 1105 AZ Amsterdam, The Netherlands
| | - Gerard A Marchal
- Department of Clinical and Experimental Cardiology, Amsterdam UMC, Heart Center, Academic Medical Center, Room K2-104.2, Meibergdreef 15, 1105 AZ Amsterdam, The Netherlands
| | - Rianne Wolswinkel
- Department of Clinical and Experimental Cardiology, Amsterdam UMC, Heart Center, Academic Medical Center, Room K2-104.2, Meibergdreef 15, 1105 AZ Amsterdam, The Netherlands
| | - John A Jansen
- Department of Medical Physiology, University Medical Center, Utrecht, The Netherlands
| | - Ingeborg van der Made
- Department of Clinical and Experimental Cardiology, Amsterdam UMC, Heart Center, Academic Medical Center, Room K2-104.2, Meibergdreef 15, 1105 AZ Amsterdam, The Netherlands
| | - Leander Beekman
- Department of Clinical and Experimental Cardiology, Amsterdam UMC, Heart Center, Academic Medical Center, Room K2-104.2, Meibergdreef 15, 1105 AZ Amsterdam, The Netherlands
| | - Adrián Ruiz-Villalba
- Department of Anatomy, Embryology & Physiology, Amsterdam UMC, Academic Medical Center, Amsterdam, The Netherlands.,Regenerative Medicine Program, Center for Applied Medical Research (CIMA), University of Navarra, IdiSNA, Pamplona, 31008, Spain
| | - Antonius Baartscheer
- Department of Clinical and Experimental Cardiology, Amsterdam UMC, Heart Center, Academic Medical Center, Room K2-104.2, Meibergdreef 15, 1105 AZ Amsterdam, The Netherlands
| | - Sridharan Rajamani
- Department of Biological Sciences, Gilead Sciences, Foster City, USA.,Department of Cardiometabolic Disorders, Amgen Inc, 1120 Veterans Blvd, South San Francisco, CA 94080, USA
| | - Luiz Belardinelli
- Department of Biological Sciences, Gilead Sciences, Foster City, USA.,InCarda Therapeutics Inc, 150 Northhill Drive, Brisbane, CA 94005, USA
| | - Toon A B van Veen
- Department of Medical Physiology, University Medical Center, Utrecht, The Netherlands
| | - Cristina Basso
- Department of Cardiac, Thoracic and Vascular Sciences, Cardiovascular Pathology, University of Padua, Italy
| | - Gaetano Thiene
- Department of Cardiac, Thoracic and Vascular Sciences, Cardiovascular Pathology, University of Padua, Italy
| | - Esther E Creemers
- Department of Clinical and Experimental Cardiology, Amsterdam UMC, Heart Center, Academic Medical Center, Room K2-104.2, Meibergdreef 15, 1105 AZ Amsterdam, The Netherlands
| | - Connie R Bezzina
- Department of Clinical and Experimental Cardiology, Amsterdam UMC, Heart Center, Academic Medical Center, Room K2-104.2, Meibergdreef 15, 1105 AZ Amsterdam, The Netherlands
| | - Carol Ann Remme
- Department of Clinical and Experimental Cardiology, Amsterdam UMC, Heart Center, Academic Medical Center, Room K2-104.2, Meibergdreef 15, 1105 AZ Amsterdam, The Netherlands
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11
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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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12
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Parrotta EI, Lucchino V, Scaramuzzino L, Scalise S, Cuda G. Modeling Cardiac Disease Mechanisms Using Induced Pluripotent Stem Cell-Derived Cardiomyocytes: Progress, Promises and Challenges. Int J Mol Sci 2020; 21:E4354. [PMID: 32575374 PMCID: PMC7352327 DOI: 10.3390/ijms21124354] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Revised: 06/12/2020] [Accepted: 06/15/2020] [Indexed: 12/12/2022] Open
Abstract
Cardiovascular diseases (CVDs) are a class of disorders affecting the heart or blood vessels. Despite progress in clinical research and therapy, CVDs still represent the leading cause of mortality and morbidity worldwide. The hallmarks of cardiac diseases include heart dysfunction and cardiomyocyte death, inflammation, fibrosis, scar tissue, hyperplasia, hypertrophy, and abnormal ventricular remodeling. The loss of cardiomyocytes is an irreversible process that leads to fibrosis and scar formation, which, in turn, induce heart failure with progressive and dramatic consequences. Both genetic and environmental factors pathologically contribute to the development of CVDs, but the precise causes that trigger cardiac diseases and their progression are still largely unknown. The lack of reliable human model systems for such diseases has hampered the unraveling of the underlying molecular mechanisms and cellular processes involved in heart diseases at their initial stage and during their progression. Over the past decade, significant scientific advances in the field of stem cell biology have literally revolutionized the study of human disease in vitro. Remarkably, the possibility to generate disease-relevant cell types from induced pluripotent stem cells (iPSCs) has developed into an unprecedented and powerful opportunity to achieve the long-standing ambition to investigate human diseases at a cellular level, uncovering their molecular mechanisms, and finally to translate bench discoveries into potential new therapeutic strategies. This review provides an update on previous and current research in the field of iPSC-driven cardiovascular disease modeling, with the aim of underlining the potential of stem-cell biology-based approaches in the elucidation of the pathophysiology of these life-threatening diseases.
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13
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Zaitsev AV, Warren M. "Heart Oddity": Intrinsically Reduced Excitability in the Right Ventricle Requires Compensation by Regionally Specific Stress Kinase Function. Front Physiol 2020; 11:86. [PMID: 32132931 PMCID: PMC7040197 DOI: 10.3389/fphys.2020.00086] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Accepted: 01/27/2020] [Indexed: 11/13/2022] Open
Abstract
The traditional view of ventricular excitation and conduction is an all-or-nothing response mediated by a regenerative activation of the inward sodium channel, which gives rise to an essentially constant conduction velocity (CV). However, whereas there is no obvious biological need to tune-up ventricular conduction, the principal molecular components determining CV, such as sodium channels, inward-rectifier potassium channels, and gap junctional channels, are known targets of the “stress” protein kinases PKA and calcium/calmodulin dependent protein kinase II (CaMKII), and are thus regulatable by signal pathways converging on these kinases. In this mini-review we will expose deficiencies and controversies in our current understanding of how ventricular conduction is regulated by stress kinases, with a special focus on the chamber-specific dimension in this regulation. In particular, we will highlight an odd property of cardiac physiology: uniform CV in ventricles requires co-existence of mutually opposing gradients in cardiac excitability and stress kinase function. While the biological advantage of this peculiar feature remains obscure, it is important to recognize the clinical implications of this phenomenon pertinent to inherited or acquired conduction diseases and therapeutic interventions modulating activity of PKA or CaMKII.
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Affiliation(s)
- Alexey V Zaitsev
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT, United States
| | - Mark Warren
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT, United States
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14
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Bayer JD, Boukens BJ, Krul SPJ, Roney CH, Driessen AHG, Berger WR, van den Berg NWE, Verkerk AO, Vigmond EJ, Coronel R, de Groot JR. Acetylcholine Delays Atrial Activation to Facilitate Atrial Fibrillation. Front Physiol 2019; 10:1105. [PMID: 31551802 PMCID: PMC6737394 DOI: 10.3389/fphys.2019.01105] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Accepted: 08/09/2019] [Indexed: 11/13/2022] Open
Abstract
Background Acetylcholine (ACh) shortens action potential duration (APD) in human atria. APD shortening facilitates atrial fibrillation (AF) by reducing the wavelength for reentry. However, the influence of ACh on electrical conduction in human atria and its contribution to AF are unclear, particularly when combined with impaired conduction from interstitial fibrosis. Objective To investigate the effect of ACh on human atrial conduction and its role in AF with computational, experimental, and clinical approaches. Methods S1S2 pacing (S1 = 600 ms and S2 = variable cycle lengths) was applied to the following human AF computer models: a left atrial appendage (LAA) myocyte to quantify the effects of ACh on APD, maximum upstroke velocity (V max ), and resting membrane potential (RMP); a monolayer of LAA myocytes to quantify the effects of ACh on conduction; and 3) an intact left atrium (LA) to determine the effects of ACh on arrhythmogenicity. Heterogeneous ACh and interstitial fibrosis were applied to the monolayer and LA models. To corroborate the simulations, APD and RMP from isolated human atrial myocytes were recorded before and after 0.1 μM ACh. At the tissue level, LAAs from AF patients were optically mapped ex vivo using Di-4-ANEPPS. The difference in total activation time (AT) was determined between AT initially recorded with S1 pacing, and AT recorded during subsequent S1 pacing without (n = 6) or with (n = 7) 100 μM ACh. Results In LAA myocyte simulations, S1 pacing with 0.1 μM ACh shortened APD by 41 ms, hyperpolarized RMP by 7 mV, and increased V max by 27 mV/ms. In human atrial myocytes, 0.1 μM ACh shortened APD by 48 ms, hyperpolarized RMP by 3 mV, and increased V max by 6 mV/ms. In LAA monolayer simulations, S1 pacing with ACh hyperpolarized RMP to delay total AT by 32 ms without and 35 ms with fibrosis. This led to unidirectional conduction block and sustained reentry in fibrotic LA with heterogeneous ACh during S2 pacing. In AF patient LAAs, S1 pacing with ACh increased total AT from 39.3 ± 26 ms to 71.4 ± 31.2 ms (p = 0.036) compared to no change without ACh (56.7 ± 29.3 ms to 50.0 ± 21.9 ms, p = 0.140). Conclusion In fibrotic atria with heterogeneous parasympathetic activation, ACh facilitates AF by shortening APD and slowing conduction to promote unidirectional conduction block and reentry.
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Affiliation(s)
- Jason D Bayer
- Electrophysiology and Heart Modeling Institute (IHU-LIRYC), Bordeaux University Foundation, Bordeaux, France.,Institute of Mathematics of Bordeaux (U5251), University of Bordeaux, Bordeaux, France
| | - Bastiaan J Boukens
- Department of Medical Biology, Academic Medical Center, Amsterdam, Netherlands
| | - Sébastien P J Krul
- Department of Cardiology, Academic Medical Center, Amsterdam, Netherlands
| | - Caroline H Roney
- Division of Imaging Sciences and Bioengineering, King's College London, London, United Kingdom
| | | | - Wouter R Berger
- Department of Cardiology, Academic Medical Center, Amsterdam, Netherlands.,Department of Cardiology, Heart Center, OLVG, Amsterdam, Netherlands
| | | | - Arie O Verkerk
- Department of Medical Biology, Academic Medical Center, Amsterdam, Netherlands.,Department of Experimental Cardiology, Academic Medical Center, Amsterdam, Netherlands
| | - Edward J Vigmond
- Electrophysiology and Heart Modeling Institute (IHU-LIRYC), Bordeaux University Foundation, Bordeaux, France.,Institute of Mathematics of Bordeaux (U5251), University of Bordeaux, Bordeaux, France
| | - Ruben Coronel
- Electrophysiology and Heart Modeling Institute (IHU-LIRYC), Bordeaux University Foundation, Bordeaux, France.,Department of Experimental Cardiology, Academic Medical Center, Amsterdam, Netherlands
| | - Joris R de Groot
- Department of Cardiology, Academic Medical Center, Amsterdam, Netherlands
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15
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Cerrone M, Remme CA, Tadros R, Bezzina CR, Delmar M. Beyond the One Gene-One Disease Paradigm: Complex Genetics and Pleiotropy in Inheritable Cardiac Disorders. Circulation 2019; 140:595-610. [PMID: 31403841 DOI: 10.1161/circulationaha.118.035954] [Citation(s) in RCA: 94] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Inheritable cardiac disorders, which may be associated with cardiomyopathic changes, are often associated with increased risk of sudden death in the young. Early linkage analysis studies in Mendelian forms of these diseases, such as hypertrophic cardiomyopathy and long-QT syndrome, uncovered large-effect genetic variants that contribute to the phenotype. In more recent years, through genotype-phenotype studies and methodological advances in genetics, it has become evident that most inheritable cardiac disorders are not monogenic but, rather, have a complex genetic basis wherein multiple genetic variants contribute (oligogenic or polygenic inheritance). Conversely, studies on genes underlying these disorders uncovered pleiotropic effects, with a single gene affecting multiple and apparently unrelated phenotypes. In this review, we explore these 2 phenomena: on the one hand, the evidence that variants in multiple genes converge to generate one clinical phenotype, and, on the other, the evidence that variants in one gene can lead to apparently unrelated phenotypes. Although multiple conditions are addressed to illustrate these concepts, the experience obtained in the study of long-QT syndrome, Brugada syndrome, and arrhythmogenic cardiomyopathy, and in the study of functions related to SCN5A (the gene coding for the α-subunit of the most abundant sodium channel in the heart) and PKP2 (the gene coding for the desmosomal protein plakophilin-2), as well, is discussed in more detail.
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Affiliation(s)
- Marina Cerrone
- Leon H. Charney Division of Cardiology (M.C., M.D.), NYU School of Medicine, New York.,Inherited Arrhythmias Clinic and Heart Rhythm Center, Leon H. Charney Division of Cardiology (M.C.), NYU School of Medicine, New York
| | - Carol Ann Remme
- Inherited Arrhythmias Clinic and Heart Rhythm Center, Leon H. Charney Division of Cardiology (M.C.), NYU School of Medicine, New York
| | - Rafik Tadros
- Amsterdam UMC, University of Amsterdam, Clinical and Experimental Cardiology, Amsterdam Cardiovascular Sciences, AMC Heart Center, The Netherlands (C.A.R., C.R.B.)
| | - Connie R Bezzina
- Inherited Arrhythmias Clinic and Heart Rhythm Center, Leon H. Charney Division of Cardiology (M.C.), NYU School of Medicine, New York
| | - Mario Delmar
- Leon H. Charney Division of Cardiology (M.C., M.D.), NYU School of Medicine, New York
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16
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Zaitsev AV, Torres NS, Cawley KM, Sabry AD, Warren JS, Warren M. Conduction in the right and left ventricle is differentially regulated by protein kinases and phosphatases: implications for arrhythmogenesis. Am J Physiol Heart Circ Physiol 2019; 316:H1507-H1527. [PMID: 30875259 PMCID: PMC6620685 DOI: 10.1152/ajpheart.00660.2018] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Revised: 02/19/2019] [Accepted: 03/07/2019] [Indexed: 12/19/2022]
Abstract
The "stress" kinases cAMP-dependent protein kinase (PKA) and calcium/calmodulin-dependent protein kinase II (CaMKII), phosphorylate the Na+ channel Nav1.5 subunit to regulate its function. However, how the channel regulation translates to ventricular conduction is poorly understood. We hypothesized that the stress kinases positively and differentially regulate conduction in the right (RV) and the left (LV) ventricles. We applied the CaMKII blocker KN93 (2.75 μM), PKA blocker H89 (10 μM), and broad-acting phosphatase blocker calyculin (30 nM) in rabbit hearts paced at a cycle length (CL) of 150-8,000 ms. We used optical mapping to determine the distribution of local conduction delays (inverse of conduction velocity). Control hearts exhibited constant and uniform conduction at all tested CLs. Calyculin (15-min perfusion) accelerated conduction, with greater effect in the RV (by 15.3%) than in the LV (by 4.1%; P < 0.05). In contrast, both KN93 and H89 slowed down conduction in a chamber-, time-, and CL-dependent manner, with the strongest effect in the RV outflow tract (RVOT). Combined KN93 and H89 synergistically promoted conduction slowing in the RV (KN93: 24.7%; H89: 29.9%; and KN93 + H89: 114.2%; P = 0.0016) but not the LV. The progressive depression of RV conduction led to conduction block and reentrant arrhythmias. Protein expression levels of both the CaMKII-δ isoform and the PKA catalytic subunit were higher in the RVOT than in the apical LV (P < 0.05). Thus normal RV conduction requires a proper balance between kinase and phosphatase activity. Dysregulation of this balance due to pharmacological interventions or disease is potentially proarrhythmic. NEW & NOTEWORTHY We show that uniform ventricular conduction requires a precise physiological balance of the activities of calcium/calmodulin-dependent protein kinase II (CaMKII), PKA, and phosphatases, which involves region-specific expression of CaMKII and PKA. Inhibiting CaMKII and/or PKA activity elicits nonuniform conduction depression, with the right ventricle becoming vulnerable to the development of conduction disturbances and ventricular fibrillation/ventricular tachycardia.
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Affiliation(s)
- Alexey V Zaitsev
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah , Salt Lake City, Utah
- Department of Bioengineering, University of Utah , Salt Lake City, Utah
| | - Natalia S Torres
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah , Salt Lake City, Utah
| | - Keiko M Cawley
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah , Salt Lake City, Utah
| | - Amira D Sabry
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah , Salt Lake City, Utah
| | - Junco S Warren
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah , Salt Lake City, Utah
- Department of Internal Medicine, School of Medicine, University of Utah , Salt Lake City, Utah
| | - Mark Warren
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah , Salt Lake City, Utah
- Department of Bioengineering, University of Utah , Salt Lake City, Utah
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17
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Rivaud MR, Baartscheer A, Verkerk AO, Beekman L, Rajamani S, Belardinelli L, Bezzina CR, Remme CA. Enhanced late sodium current underlies pro-arrhythmic intracellular sodium and calcium dysregulation in murine sodium channelopathy. Int J Cardiol 2018; 263:54-62. [PMID: 29754923 DOI: 10.1016/j.ijcard.2018.03.044] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Revised: 02/23/2018] [Accepted: 03/09/2018] [Indexed: 12/20/2022]
Abstract
BACKGROUND Long QT syndrome mutations in the SCN5A gene are associated with an enhanced late sodium current (INa,L) which may lead to pro-arrhythmic action potential prolongation and intracellular calcium dysregulation. We here investigated the dynamic relation between INa,L, intracellular sodium ([Na+]i) and calcium ([Ca2+]i) homeostasis and pro-arrhythmic events in the setting of a SCN5A mutation. METHODS AND RESULTS Wild-type (WT) and Scn5a1798insD/+ (MUT) mice (age 3-5 months) carrying the murine homolog of the SCN5A-1795insD mutation on two distinct genetic backgrounds (FVB/N and 129P2) were studied. [Na+]i, [Ca2+]i and Ca2+ transient amplitude were significantly increased in 129P2-MUT myocytes as compared to WT, but not in FVB/N-MUT. Accordingly, INa,L wassignificantly more enhanced in 129P2-MUT than in FVB/N-MUT myocytes, consistent with a dose-dependent correlation. Quantitative RT-PCR analysis revealed intrinsic differences in mRNA expression levels of the sodium/potassium pump, the sodium/hydrogen exchanger, and sodium‑calcium exchanger between the two mouse strains. The rate of increase in [Na+]i, [Ca2+]i and Ca2+ transient amplitude following the application of the Na+/K+-ATPase inhibitor ouabain was significantly greater in 129P2-MUT than in 129P2-WT myocytes and was normalized by the INa,L inhibitor ranolazine. Furthermore, ranolazine decreased the incidence of pro-arrhythmic calcium after-transients elicited in 129P2-MUT myocytes. CONCLUSIONS In this study we established a causal link between the magnitude of INa,L, extent of Na+ and Ca2+ dysregulation, and incidence of pro-arrhythmic events in murine Scn5a1798insD/+ myocytes. Furthermore, our findings provide mechanistic insight into the anti-arrhythmic potential of pharmacological inhibition of INa,L in patients with LQT3 syndrome.
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Affiliation(s)
- Mathilde R Rivaud
- Heart Center, Department of Clinical and Experimental Cardiology, Academic Medical Center, Meibergdreef 15, 1105AZ Amsterdam, The Netherlands
| | - Antonius Baartscheer
- Heart Center, Department of Clinical and Experimental Cardiology, Academic Medical Center, Meibergdreef 15, 1105AZ Amsterdam, The Netherlands
| | - Arie O Verkerk
- Heart Center, Department of Clinical and Experimental Cardiology, Academic Medical Center, Meibergdreef 15, 1105AZ Amsterdam, The Netherlands; Department of Medical Biology, Academic Medical Center, Meibergdreef 15, 1105AZ Amsterdam, The Netherlands
| | - Leander Beekman
- Heart Center, Department of Clinical and Experimental Cardiology, Academic Medical Center, Meibergdreef 15, 1105AZ Amsterdam, The Netherlands
| | | | | | - Connie R Bezzina
- Heart Center, Department of Clinical and Experimental Cardiology, Academic Medical Center, Meibergdreef 15, 1105AZ Amsterdam, The Netherlands
| | - Carol Ann Remme
- Heart Center, Department of Clinical and Experimental Cardiology, Academic Medical Center, Meibergdreef 15, 1105AZ Amsterdam, The Netherlands.
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18
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Verkerk AO, Amin AS, Remme CA. Disease Modifiers of Inherited SCN5A Channelopathy. Front Cardiovasc Med 2018; 5:137. [PMID: 30327767 PMCID: PMC6174200 DOI: 10.3389/fcvm.2018.00137] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Accepted: 09/10/2018] [Indexed: 12/19/2022] Open
Abstract
To date, a large number of mutations in SCN5A, the gene encoding the pore-forming α-subunit of the primary cardiac Na+ channel (NaV1.5), have been found in patients presenting with a wide range of ECG abnormalities and cardiac syndromes. Although these mutations all affect the same NaV1.5 channel, the associated cardiac syndromes each display distinct phenotypical and biophysical characteristics. Variable disease expressivity has also been reported, where one particular mutation in SCN5A may lead to either one particular symptom, a range of various clinical signs, or no symptoms at all, even within one single family. Additionally, disease severity may vary considerably between patients carrying the same mutation. The exact reasons are unknown, but evidence is increasing that various cardiac and non-cardiac conditions can influence the expressivity and severity of inherited SCN5A channelopathies. In this review, we provide a summary of identified disease entities caused by SCN5A mutations, and give an overview of co-morbidities and other (non)-genetic factors which may modify SCN5A channelopathies. A comprehensive knowledge of these modulatory factors is not only essential for a complete understanding of the diverse clinical phenotypes associated with SCN5A mutations, but also for successful development of effective risk stratification and (alternative) treatment paradigms.
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Affiliation(s)
- Arie O Verkerk
- Department of Clinical and Experimental Cardiology, Heart Centre, Academic Medical Center, Amsterdam, Netherlands.,Department of Medical Biology, Academic Medical Center, Amsterdam, Netherlands
| | - Ahmad S Amin
- Department of Clinical and Experimental Cardiology, Heart Centre, Academic Medical Center, Amsterdam, Netherlands
| | - Carol Ann Remme
- Department of Clinical and Experimental Cardiology, Heart Centre, Academic Medical Center, Amsterdam, Netherlands
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19
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Giudicessi JR, Wilde AAM, Ackerman MJ. The genetic architecture of long QT syndrome: A critical reappraisal. Trends Cardiovasc Med 2018; 28:453-464. [PMID: 29661707 DOI: 10.1016/j.tcm.2018.03.003] [Citation(s) in RCA: 84] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/26/2018] [Revised: 03/19/2018] [Accepted: 03/21/2018] [Indexed: 12/19/2022]
Abstract
Collectively, the completion of the Human Genome Project and subsequent development of high-throughput next-generation sequencing methodologies have revolutionized genomic research. However, the rapid sequencing and analysis of thousands upon thousands of human exomes and genomes has taught us that most genes, including those known to cause heritable cardiovascular disorders such as long QT syndrome, harbor an unexpected background rate of rare, and presumably innocuous, non-synonymous genetic variation. In this Review, we aim to reappraise the genetic architecture underlying both the acquired and congenital forms of long QT syndrome by examining how the clinical phenotype associated with and background genetic variation in long QT syndrome-susceptibility genes impacts the clinical validity of existing gene-disease associations and the variant classification and reporting strategies that serve as the foundation for diagnostic long QT syndrome genetic testing.
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Affiliation(s)
- John R Giudicessi
- Department of Cardiovascular Medicine (Cardiovascular Diseases Fellowship and Clinician-Investigator Training Programs), Mayo Clinic, Rochester, MN, United States
| | - Arthur A M Wilde
- Department of Medicine (Division of Cardiology), Columbia University Irving Medical Center, New York, NY, United States; Department of Clinical & Experimental Cardiology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Michael J Ackerman
- Departments of Cardiovascular Medicine (Division of Heart Rhythm Services), Pediatrics (Division of Pediatric Cardiology), and Molecular Pharmacology & Experimental Therapeutics (Windland Smith Rice Sudden Death Genomics Laboratory), Mayo Clinic, Rochester, MN, United States.
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20
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Sinus Bradycardia in Carriers of the SCN5A-1795insD Mutation: Unraveling the Mechanism through Computer Simulations. Int J Mol Sci 2018; 19:ijms19020634. [PMID: 29473904 PMCID: PMC5855856 DOI: 10.3390/ijms19020634] [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: 01/08/2018] [Revised: 02/13/2018] [Accepted: 02/19/2018] [Indexed: 11/25/2022] Open
Abstract
The SCN5A gene encodes the pore-forming α-subunit of the ion channel that carries the cardiac fast sodium current (INa). The 1795insD mutation in SCN5A causes sinus bradycardia, with a mean heart rate of 70 beats/min in mutation carriers vs. 77 beats/min in non-carriers from the same family (lowest heart rate 41 vs. 47 beats/min). To unravel the underlying mechanism, we incorporated the mutation-induced changes in INa into a recently developed comprehensive computational model of a single human sinoatrial node cell (Fabbri–Severi model). The 1795insD mutation reduced the beating rate of the model cell from 74 to 69 beats/min (from 49 to 43 beats/min in the simulated presence of 20 nmol/L acetylcholine). The mutation-induced persistent INa per se resulted in a substantial increase in beating rate. This gain-of-function effect was almost completely counteracted by the loss-of-function effect of the reduction in INa conductance. The further loss-of-function effect of the shifts in steady-state activation and inactivation resulted in an overall loss-of-function effect of the 1795insD mutation. We conclude that the experimentally identified mutation-induced changes in INa can explain the clinically observed sinus bradycardia. Furthermore, we conclude that the Fabbri–Severi model may prove a useful tool in understanding cardiac pacemaker activity in humans.
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21
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Schwartz PJ, Crotti L. Founder populations with channelopathies and church records reveal all sorts of interesting secrets: Some are scientifically relevant. Heart Rhythm 2017; 14:1882-1883. [DOI: 10.1016/j.hrthm.2017.09.016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Indexed: 11/25/2022]
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Symonds JD, Zuberi SM. Genetics update: Monogenetics, polygene disorders and the quest for modifying genes. Neuropharmacology 2017; 132:3-19. [PMID: 29037745 DOI: 10.1016/j.neuropharm.2017.10.013] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Revised: 10/09/2017] [Accepted: 10/11/2017] [Indexed: 12/19/2022]
Abstract
The genetic channelopathies are a broad collection of diseases. Many ion channel genes demonstrate wide phenotypic pleiotropy, but nonetheless concerted efforts have been made to characterise genotype-phenotype relationships. In this review we give an overview of the factors that influence genotype-phenotype relationships across this group of diseases as a whole, using specific individual channelopathies as examples. We suggest reasons for the limitations observed in these relationships. We discuss the role of ion channel variation in polygenic disease and highlight research that has contributed to unravelling the complex aetiological nature of these conditions. We focus specifically on the quest for modifying genes in inherited channelopathies, using the voltage-gated sodium channels as an example. Epilepsy related to genetic channelopathy is one area in which precision medicine is showing promise. We will discuss the successes and limitations of precision medicine in these conditions. This article is part of the Special Issue entitled 'Channelopathies.'
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Affiliation(s)
- Joseph D Symonds
- The Paediatric Neurosciences Research Group, Royal Hospital for Children, Queen Elizabeth University Hospitals, Glasgow, UK; School of Medicine, University of Glasgow, Glasgow, UK
| | - Sameer M Zuberi
- The Paediatric Neurosciences Research Group, Royal Hospital for Children, Queen Elizabeth University Hospitals, Glasgow, UK; School of Medicine, University of Glasgow, Glasgow, UK.
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Symonds JD, Zuberi SM. WITHDRAWN: Genetics update: Monogenetics, polygene disorders and the quest for modifying genes. Neuropharmacology 2017:S0028-3908(17)30347-7. [PMID: 28757052 DOI: 10.1016/j.neuropharm.2017.07.016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Accepted: 07/17/2017] [Indexed: 11/15/2022]
Abstract
The Publisher regrets that this article is an accidental duplication of an article that has already been published, https://doi.org/10.1016/j.neuropharm.2017.10.013. The duplicate article has therefore been withdrawn. The full Elsevier Policy on Article Withdrawal can be found at https://www.elsevier.com/about/our-business/policies/article-withdrawal.
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Affiliation(s)
- Joseph D Symonds
- The Paediatric Neurosciences Research Group, Royal Hospital for Children, Queen Elizabeth University Hospitals, Glasgow, UK; School of Medicine, University of Glasgow, Glasgow, UK
| | - Sameer M Zuberi
- The Paediatric Neurosciences Research Group, Royal Hospital for Children, Queen Elizabeth University Hospitals, Glasgow, UK; School of Medicine, University of Glasgow, Glasgow, UK
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Ackers-Johnson M, Li PY, Holmes AP, O'Brien SM, Pavlovic D, Foo RS. A Simplified, Langendorff-Free Method for Concomitant Isolation of Viable Cardiac Myocytes and Nonmyocytes From the Adult Mouse Heart. Circ Res 2016; 119:909-20. [PMID: 27502479 DOI: 10.1161/circresaha.116.309202] [Citation(s) in RCA: 315] [Impact Index Per Article: 39.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/29/2016] [Accepted: 08/05/2016] [Indexed: 11/16/2022]
Abstract
RATIONALE Cardiovascular disease represents a global pandemic. The advent of and recent advances in mouse genomics, epigenomics, and transgenics offer ever-greater potential for powerful avenues of research. However, progress is often constrained by unique complexities associated with the isolation of viable myocytes from the adult mouse heart. Current protocols rely on retrograde aortic perfusion using specialized Langendorff apparatus, which poses considerable logistical and technical barriers to researchers and demands extensive training investment. OBJECTIVE To identify and optimize a convenient, alternative approach, allowing the robust isolation and culture of adult mouse cardiac myocytes using only common surgical and laboratory equipment. METHODS AND RESULTS Cardiac myocytes were isolated with yields comparable to those in published Langendorff-based methods, using direct needle perfusion of the LV ex vivo and without requirement for heparin injection. Isolated myocytes can be cultured antibiotic free, with retained organized contractile and mitochondrial morphology, transcriptional signatures, calcium handling, responses to hypoxia, neurohormonal stimulation, and electric pacing, and are amenable to patch clamp and adenoviral gene transfer techniques. Furthermore, the methodology permits concurrent isolation, separation, and coculture of myocyte and nonmyocyte cardiac populations. CONCLUSIONS We present a novel, simplified method, demonstrating concomitant isolation of viable cardiac myocytes and nonmyocytes from the same adult mouse heart. We anticipate that this new approach will expand and accelerate innovative research in the field of cardiac biology.
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Affiliation(s)
- Matthew Ackers-Johnson
- From the Cardiovascular Research Institute, Centre for Translational Medicine MD6, National University Health System, Singapore (M.A.-J., P.Y.L., R.S.F.); Genome Institute of Singapore (M.A.-J., R.S.F.); and Institute of Cardiovascular Sciences, University of Birmingham, UK (A.P.H., S.-M.O., D.P.)
| | - Peter Yiqing Li
- From the Cardiovascular Research Institute, Centre for Translational Medicine MD6, National University Health System, Singapore (M.A.-J., P.Y.L., R.S.F.); Genome Institute of Singapore (M.A.-J., R.S.F.); and Institute of Cardiovascular Sciences, University of Birmingham, UK (A.P.H., S.-M.O., D.P.)
| | - Andrew P Holmes
- From the Cardiovascular Research Institute, Centre for Translational Medicine MD6, National University Health System, Singapore (M.A.-J., P.Y.L., R.S.F.); Genome Institute of Singapore (M.A.-J., R.S.F.); and Institute of Cardiovascular Sciences, University of Birmingham, UK (A.P.H., S.-M.O., D.P.)
| | - Sian-Marie O'Brien
- From the Cardiovascular Research Institute, Centre for Translational Medicine MD6, National University Health System, Singapore (M.A.-J., P.Y.L., R.S.F.); Genome Institute of Singapore (M.A.-J., R.S.F.); and Institute of Cardiovascular Sciences, University of Birmingham, UK (A.P.H., S.-M.O., D.P.)
| | - Davor Pavlovic
- From the Cardiovascular Research Institute, Centre for Translational Medicine MD6, National University Health System, Singapore (M.A.-J., P.Y.L., R.S.F.); Genome Institute of Singapore (M.A.-J., R.S.F.); and Institute of Cardiovascular Sciences, University of Birmingham, UK (A.P.H., S.-M.O., D.P.)
| | - Roger S Foo
- From the Cardiovascular Research Institute, Centre for Translational Medicine MD6, National University Health System, Singapore (M.A.-J., P.Y.L., R.S.F.); Genome Institute of Singapore (M.A.-J., R.S.F.); and Institute of Cardiovascular Sciences, University of Birmingham, UK (A.P.H., S.-M.O., D.P.).
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25
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Liu M, Yang KC, Dudley SC. Cardiac Sodium Channel Mutations: Why so Many Phenotypes? CURRENT TOPICS IN MEMBRANES 2016; 78:513-59. [PMID: 27586294 DOI: 10.1016/bs.ctm.2015.12.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The cardiac Na(+) channel (Nav1.5) conducts a depolarizing inward Na(+) current that is responsible for the generation of the upstroke Phase 0 of the action potential. In heart tissue, changes in Na(+) currents can affect conduction velocity and impulse propagation. The cardiac Nav1.5 is also involved in determination of the action potential duration, since some channels may reopen during the plateau phase, generating a persistent or late inward current. Mutations of cardiac Nav1.5 can induce gain or loss of channel function because of an increased late current or a decrease of peak current, respectively. Gain-of-function mutations cause Long QT syndrome type 3 and possibly atrial fibrillation, while loss-of-function channel mutations are associated with a wider variety of phenotypes, such as Brugada syndrome, cardiac conduction disease, dilated cardiomyopathy, and sick sinus node syndrome. The penetrance and phenotypes resulting from Nav1.5 mutations also vary with age, gender, body temperature, circadian rhythm, and between regions of the heart. This phenotypic variability makes it difficult to correlate genotype-phenotype. We propose that mutations are only one contributor to the phenotype and additional modifications on Nav1.5 lead to the phenotypic variability. Possible modifiers include other genetic variations and alterations in the life cycle of Nav1.5 such as gene transcription, RNA processing, translation, posttranslational modifications, trafficking, complex assembly, and degradation. In this chapter, we summarize potential modifiers of cardiac Nav1.5 that could help explain the clinically observed phenotypic variability. Consideration of these modifiers could help improve genotype-phenotype correlations and lead to new therapeutic strategies.
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Affiliation(s)
- M Liu
- The Warren Alpert Medical School of Brown University, Providence, RI, United States
| | - K-C Yang
- The Warren Alpert Medical School of Brown University, Providence, RI, United States
| | - S C Dudley
- The Warren Alpert Medical School of Brown University, Providence, RI, United States
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26
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Basheer WA, Harris BS, Mentrup HL, Abreha M, Thames EL, Lea JB, Swing DA, Copeland NG, Jenkins NA, Price RL, Matesic LE. Cardiomyocyte-specific overexpression of the ubiquitin ligase Wwp1 contributes to reduction in Connexin 43 and arrhythmogenesis. J Mol Cell Cardiol 2015; 88:1-13. [PMID: 26386426 DOI: 10.1016/j.yjmcc.2015.09.004] [Citation(s) in RCA: 36] [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: 05/08/2015] [Revised: 08/30/2015] [Accepted: 09/14/2015] [Indexed: 12/12/2022]
Abstract
Gap junctions (GJ) are intercellular channels composed of connexin subunits that play a critical role in a diverse number of cellular processes in all tissue types. In the heart, GJs mediate electrical coupling between cardiomyocytes and display mislocalization and/or downregulation in cardiac disease (a process known as GJ remodeling), producing an arrhythmogenic substrate. The main constituent of GJs in the ventricular myocardium is Connexin 43 (Cx43), an integral membrane protein that is rapidly turned over and shows decreased expression or function with age. We hypothesized that Wwp1, an ubiquitin ligase whose expression in known to increase in aging-related pathologies, may regulate Cx43 in vivo by targeting it for ubiquitylation and degradation and yield tissue-specific Cx43 loss of function phenotypes. When Wwp1 was globally overexpressed in mice under the control of a β-actin promoter, the highest induction of Wwp1 expression was observed in the heart which was associated with a 90% reduction in cardiac Cx43 protein levels, left ventricular hypertrophy (LVH), and the development of lethal ventricular arrhythmias around 8weeks of age. This phenotype was completely penetrant in two independent founder lines. Cardiomyocyte-specific overexpression of Wwp1 confirmed that this phenotype was cell autonomous and delineated Cx43-dependent and -independent roles for Wwp1 in arrhythmogenesis and LVH, respectively. Using a cell-based system, it was determined that Wwp1 co-immunoprecipitates with and ubiquitylates Cx43, causing a decrease in the steady state levels of Cx43 protein. These findings offer new mechanistic insights into the regulation of Cx43 which may be exploitable in various gap junctionopathies.
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MESH Headings
- Actins/genetics
- Actins/metabolism
- Animals
- Arrhythmias, Cardiac/genetics
- Arrhythmias, Cardiac/metabolism
- Arrhythmias, Cardiac/pathology
- Connexin 43/genetics
- Connexin 43/metabolism
- Disease Models, Animal
- Female
- Gap Junctions/metabolism
- Gap Junctions/pathology
- Gene Expression Regulation
- Heart Ventricles/metabolism
- Heart Ventricles/pathology
- Hypertrophy, Left Ventricular/genetics
- Hypertrophy, Left Ventricular/metabolism
- Hypertrophy, Left Ventricular/pathology
- Male
- Mice
- Mice, Transgenic
- Myocardium/metabolism
- Myocardium/pathology
- Myocytes, Cardiac/metabolism
- Myocytes, Cardiac/pathology
- Phenotype
- Promoter Regions, Genetic
- Proteasome Endopeptidase Complex/metabolism
- Protein Stability
- Proteolysis
- Signal Transduction
- Ubiquitin-Protein Ligases/genetics
- Ubiquitin-Protein Ligases/metabolism
- Ubiquitination
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Affiliation(s)
- Wassim A Basheer
- Department of Biological Sciences, University of South Carolina, Columbia, SC 29208, USA
| | - Brett S Harris
- Department of Regenerative Medicine and Cell Biology, Medical University of South Carolina, Charleston, SC 29425, USA
| | - Heather L Mentrup
- Department of Biological Sciences, University of South Carolina, Columbia, SC 29208, USA
| | - Measho Abreha
- Department of Biological Sciences, University of South Carolina, Columbia, SC 29208, USA
| | - Elizabeth L Thames
- Department of Biological Sciences, University of South Carolina, Columbia, SC 29208, USA
| | - Jessica B Lea
- Department of Biological Sciences, University of South Carolina, Columbia, SC 29208, USA
| | - Deborah A Swing
- Mouse Cancer Genetics Program, The National Cancer Institute at Frederick, Frederick, MD 21702, USA
| | - Neal G Copeland
- Mouse Cancer Genetics Program, The National Cancer Institute at Frederick, Frederick, MD 21702, USA
| | - Nancy A Jenkins
- Mouse Cancer Genetics Program, The National Cancer Institute at Frederick, Frederick, MD 21702, USA
| | - Robert L Price
- Department of Cell Biology and Anatomy, University of South Carolina School of Medicine, Columbia, SC 29209, USA
| | - Lydia E Matesic
- Department of Biological Sciences, University of South Carolina, Columbia, SC 29208, USA.
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27
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Milano A, Lodder EM, Bezzina CR. TNNI3K in cardiovascular disease and prospects for therapy. J Mol Cell Cardiol 2015; 82:167-73. [PMID: 25787061 DOI: 10.1016/j.yjmcc.2015.03.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/09/2014] [Revised: 02/23/2015] [Accepted: 03/09/2015] [Indexed: 12/26/2022]
Abstract
Cardiovascular diseases are an important cause of morbidity and mortality worldwide and the global burden of these diseases continues to grow. Therefore new therapies are urgently needed. The role of protein kinases in disease, including cardiac disease, is long recognized, making kinases important therapeutic targets. We here review the knowledge gathered in the last decade about troponin I-interacting kinase (TNNI3K), a kinase with cardiac-restricted expression that has been implicated in various cardiac phenotypes and diseases including heart failure, cardiomyopathy, ischemia/reperfusion injury and conduction of the cardiac electrical impulse.
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Affiliation(s)
- Annalisa Milano
- Department of Clinical and Experimental Cardiology, Academic Medical Centre, Amsterdam, The Netherlands
| | - Elisabeth M Lodder
- Department of Clinical and Experimental Cardiology, Academic Medical Centre, Amsterdam, The Netherlands
| | - Connie R Bezzina
- Department of Clinical and Experimental Cardiology, Academic Medical Centre, Amsterdam, The Netherlands.
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28
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Abstract
Sodium current in the heart flows principally through the pore protein NaV1.5, which is part of a complex of interacting proteins that serve both to target and localize the complex in the membrane, and to modulate function by such post-translational modifications as phosphorylation and nitrosylation. Multiple mutations in seven different NaV1.5 interacting proteins have been associated with dysfunctional sodium current and inherited cardiac diseases, including long QT syndrome, Brugada syndrome, atrial fibrillation, and cardiomyopathy, as well as sudden infant death syndrome (SIDS). Mutations in as yet unidentified interacting proteins may account for cardiac disease for which a genetic basis has not yet been established. Characterizing the mechanisms by which these mutations cause disease may give insight into etiologies and treatments of more common acquired cardiac disease, such as ischemia and heart failure.
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Affiliation(s)
- John W Kyle
- Department of Medicine, Division of Cardiovascular Medicine, University of Wisconsin, Madison, Wisconsin, USA 53792
| | - Jonathan C Makielski
- Department of Medicine, Division of Cardiovascular Medicine, University of Wisconsin, Madison, Wisconsin, USA 53792
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29
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Abstract
Mutations of the cardiac sodium channel (Nav1.5) can induce gain or loss of channel function. Gain-of-function mutations can cause long QT syndrome type 3 and possibly atrial fibrillation, whereas loss-of-function mutations are associated with a variety of phenotypes, such as Brugada syndrome, cardiac conduction disease, sick sinus syndrome, and possibly dilated cardiomyopathy. The phenotypes produced by Nav1.5 mutations vary according to the direct effect of the mutation on channel biophysics, but also with age, sex, body temperature, and between regions of the heart. This phenotypic variability makes genotype-phenotype correlations difficult. In this Perspectives article, we propose that phenotypic variability not ascribed to mutation-dependent changes in channel function might be the result of additional modifiers of channel behaviour, such as other genetic variation and alterations in transcription, RNA processing, translation, post-translational modifications, and protein degradation. Consideration of these modifiers might help to improve genotype-phenotype correlations and lead to new therapeutic strategies.
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Affiliation(s)
- Man Liu
- Warren Alpert Medical School, Brown University, 593 Eddy Street, APC730, Providence, RI 02903, USA
| | - Kai-Chien Yang
- Warren Alpert Medical School, Brown University, 593 Eddy Street, APC730, Providence, RI 02903, USA
| | - Samuel C Dudley
- Warren Alpert Medical School, Brown University, 593 Eddy Street, APC730, Providence, RI 02903, USA
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30
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Lodder EM, Scicluna BP, Beekman L, Arends D, Moerland PD, Tanck MWT, Adriaens ME, Bezzina CR. Integrative genomic approach identifies multiple genes involved in cardiac collagen deposition. ACTA ACUST UNITED AC 2014; 7:790-8. [PMID: 25217174 DOI: 10.1161/circgenetics.114.000537] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND With aging and in cardiac disease, fibrosis caused by collagen deposition is increased, impairing contractility and providing a substrate for arrhythmia. In this study, we set out to identify genetic modifiers of collagen deposition in the heart by exploiting the genetic variability among F2 progeny of 129P2 and FVBN/J mice carrying the Scn5a(tm1Care/+) mutation. METHODS AND RESULTS Relative amounts of collagen were determined in left ventricular myocardium of 65 F2-mice and combined with genome-wide genotypic and cardiac expression data to identify collagen quantitative trait loci (QTLs) and overlapping expression QTLs (eQTLs). A significant collagen QTL was identified on mouse Chr8; an additional collagen QTL was identified on mouse Chr2 after correction for a genetic covariate uncovered on Chr18 using multiple QTL mapping. Of the 24 eQTLs colocalizing with the Chr8-collagen QTL, 6 transcripts were correlated with relative collagen amount. Similarly, of the 7 eQTLs colocalizing with the Chr2-collagen QTL, 1 transcript, Gpr158, correlated with relative collagen. Of the 12 transcripts with an eQTLs in the Chr18-covariate region, only Fgf1 correlated with relative collagen amount. Furthermore, 2 of the transcripts, Pdlim3 (Chr8) and Itga6 (Chr2), with eQTLs overlapping with collagen QTLs, had a genetic covariate on Chr18 that coincided with the Chr18 collagen covariate locus. Application of recombinant human FGF1 to isolated cardiac fibroblasts in culture affected the level of expression of Pdlim3, Itga6, and Gpr158. CONCLUSIONS We here mapped a possible novel genetic network modulating collagen deposition in mouse left ventricular myocardium.
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Affiliation(s)
- Elisabeth M Lodder
- From the Department of Experimental Cardiology (E.M.L., B.P.S., L.B., M.E.A., C.R.B.), and Department of Clinical Epidemiology, Biostatistics and Bioinformatics (P.D.M., M.W.T.T.), University of Amsterdam, Academic Medical Center, Amsterdam, Netherlands; and Groningen Bioinformatics Centre, University of Groningen, Groningen, Netherlands (D.A.)
| | - Brendon P Scicluna
- From the Department of Experimental Cardiology (E.M.L., B.P.S., L.B., M.E.A., C.R.B.), and Department of Clinical Epidemiology, Biostatistics and Bioinformatics (P.D.M., M.W.T.T.), University of Amsterdam, Academic Medical Center, Amsterdam, Netherlands; and Groningen Bioinformatics Centre, University of Groningen, Groningen, Netherlands (D.A.)
| | - Leander Beekman
- From the Department of Experimental Cardiology (E.M.L., B.P.S., L.B., M.E.A., C.R.B.), and Department of Clinical Epidemiology, Biostatistics and Bioinformatics (P.D.M., M.W.T.T.), University of Amsterdam, Academic Medical Center, Amsterdam, Netherlands; and Groningen Bioinformatics Centre, University of Groningen, Groningen, Netherlands (D.A.)
| | - Danny Arends
- From the Department of Experimental Cardiology (E.M.L., B.P.S., L.B., M.E.A., C.R.B.), and Department of Clinical Epidemiology, Biostatistics and Bioinformatics (P.D.M., M.W.T.T.), University of Amsterdam, Academic Medical Center, Amsterdam, Netherlands; and Groningen Bioinformatics Centre, University of Groningen, Groningen, Netherlands (D.A.)
| | - Perry D Moerland
- From the Department of Experimental Cardiology (E.M.L., B.P.S., L.B., M.E.A., C.R.B.), and Department of Clinical Epidemiology, Biostatistics and Bioinformatics (P.D.M., M.W.T.T.), University of Amsterdam, Academic Medical Center, Amsterdam, Netherlands; and Groningen Bioinformatics Centre, University of Groningen, Groningen, Netherlands (D.A.)
| | - Michael W T Tanck
- From the Department of Experimental Cardiology (E.M.L., B.P.S., L.B., M.E.A., C.R.B.), and Department of Clinical Epidemiology, Biostatistics and Bioinformatics (P.D.M., M.W.T.T.), University of Amsterdam, Academic Medical Center, Amsterdam, Netherlands; and Groningen Bioinformatics Centre, University of Groningen, Groningen, Netherlands (D.A.)
| | - Michiel E Adriaens
- From the Department of Experimental Cardiology (E.M.L., B.P.S., L.B., M.E.A., C.R.B.), and Department of Clinical Epidemiology, Biostatistics and Bioinformatics (P.D.M., M.W.T.T.), University of Amsterdam, Academic Medical Center, Amsterdam, Netherlands; and Groningen Bioinformatics Centre, University of Groningen, Groningen, Netherlands (D.A.)
| | - Connie R Bezzina
- From the Department of Experimental Cardiology (E.M.L., B.P.S., L.B., M.E.A., C.R.B.), and Department of Clinical Epidemiology, Biostatistics and Bioinformatics (P.D.M., M.W.T.T.), University of Amsterdam, Academic Medical Center, Amsterdam, Netherlands; and Groningen Bioinformatics Centre, University of Groningen, Groningen, Netherlands (D.A.).
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Kusumoto S, Kawano H, Makita N, Ichimaru S, Kaku T, Haruta D, Hida A, Sera N, Imaizumi M, Nakashima E, Maemura K, Akahoshi M. Right bundle branch block without overt heart disease predicts higher risk of pacemaker implantation: The study of atomic-bomb survivors. Int J Cardiol 2014; 174:77-82. [DOI: 10.1016/j.ijcard.2014.03.152] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/31/2013] [Revised: 02/14/2014] [Accepted: 03/22/2014] [Indexed: 11/26/2022]
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Calhoun JD, Isom LL. The role of non-pore-forming β subunits in physiology and pathophysiology of voltage-gated sodium channels. Handb Exp Pharmacol 2014; 221:51-89. [PMID: 24737232 DOI: 10.1007/978-3-642-41588-3_4] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Voltage-gated sodium channel β1 and β2 subunits were discovered as auxiliary proteins that co-purify with pore-forming α subunits in brain. The other family members, β1B, β3, and β4, were identified by homology and shown to modulate sodium current in heterologous systems. Work over the past 2 decades, however, has provided strong evidence that these proteins are not simply ancillary ion channel subunits, but are multifunctional signaling proteins in their own right, playing both conducting (channel modulatory) and nonconducting roles in cell signaling. Here, we discuss evidence that sodium channel β subunits not only regulate sodium channel function and localization but also modulate voltage-gated potassium channels. In their nonconducting roles, VGSC β subunits function as immunoglobulin superfamily cell adhesion molecules that modulate brain development by influencing cell proliferation and migration, axon outgrowth, axonal fasciculation, and neuronal pathfinding. Mutations in genes encoding β subunits are linked to paroxysmal diseases including epilepsy, cardiac arrhythmia, and sudden infant death syndrome. Finally, β subunits may be targets for the future development of novel therapeutics.
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Affiliation(s)
- Jeffrey D Calhoun
- Department of Pharmacology, University of Michigan, Ann Arbor, MI, 48109-5632, USA
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Kawakami H, Aiba T, Yamada T, Okayama H, Kazatani Y, Konishi K, Nakajima I, Miyamoto K, Yamada Y, Okamura H, Noda T, Satomi K, Kamakura S, Makita N, Shimizu W. Variable phenotype expression with a frameshift mutation of the cardiac sodium channel gene SCN5A. J Arrhythm 2013. [DOI: 10.1016/j.joa.2013.04.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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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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Zanella F, Lyon RC, Sheikh F. Modeling heart disease in a dish: from somatic cells to disease-relevant cardiomyocytes. Trends Cardiovasc Med 2013; 24:32-44. [PMID: 24054750 DOI: 10.1016/j.tcm.2013.06.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/06/2013] [Revised: 06/07/2013] [Accepted: 06/10/2013] [Indexed: 01/02/2023]
Abstract
A scientific milestone that has tremendously impacted the cardiac research field has been the discovery and establishment of human-induced pluripotent stem cells (hiPSC). Key to this discovery has been uncovering a viable path in generating human patient and disease-specific cardiac cells to dynamically model and study human cardiac diseases in an in vitro setting. Recent studies have demonstrated that hiPSC-derived cardiomyocytes can be used to model and recapitulate various known disease features in hearts of patient donors harboring genetic-based cardiac diseases. Experimental drugs have also been tested in this setting and shown to alleviate disease phenotypes in hiPSC-derived cardiomyocytes, further paving the way for therapeutic interventions for cardiac disease. Here, we review state-of-the-art methods to generate high-quality hiPSC and differentiate them towards cardiomyocytes as well as the full range of genetic-based cardiac diseases, which have been modeled using hiPSC. We also provide future perspectives on exploiting the potential of hiPSC to compliment existing studies and gain new insights into the mechanisms underlying cardiac disease.
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Affiliation(s)
- Fabian Zanella
- Department of Medicine (Cardiology Division), University of California-San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Robert C Lyon
- Department of Medicine (Cardiology Division), University of California-San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Farah Sheikh
- Department of Medicine (Cardiology Division), University of California-San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA.
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Adsit GS, Vaidyanathan R, Galler CM, Kyle JW, Makielski JC. Channelopathies from mutations in the cardiac sodium channel protein complex. J Mol Cell Cardiol 2013; 61:34-43. [PMID: 23557754 PMCID: PMC3720718 DOI: 10.1016/j.yjmcc.2013.03.017] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/02/2013] [Revised: 03/15/2013] [Accepted: 03/21/2013] [Indexed: 12/19/2022]
Abstract
The cardiac sodium current underlies excitability in heart, and inherited abnormalities of the proteins regulating and conducting this current cause inherited arrhythmia syndromes. This review focuses on inherited mutations in non-pore forming proteins of sodium channel complexes that cause cardiac arrhythmia, and the deduced mechanisms by which they affect function and dysfunction of the cardiac sodium current. Defining the structure and function of these complexes and how they are regulated will contribute to understanding the possible roles for this complex in normal and abnormal physiology and homeostasis. This article is part of a Special Issue entitled "Na(+) Regulation in Cardiac Myocytes".
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Affiliation(s)
- Graham S. Adsit
- Department of Medicine, Division of Cardiovascular Medicine, University of Wisconsin, Madison, Wisconsin, USA 53792
| | - Ravi Vaidyanathan
- Department of Medicine, Division of Cardiovascular Medicine, University of Wisconsin, Madison, Wisconsin, USA 53792
| | - Carla M. Galler
- School of Business and Applied Arts, Division of Visual Communication, Madison College, Madison, WI, USA 53704
| | - John W. Kyle
- Department of Medicine, Division of Cardiovascular Medicine, University of Wisconsin, Madison, Wisconsin, USA 53792
| | - Jonathan C. Makielski
- Department of Medicine, Division of Cardiovascular Medicine, University of Wisconsin, Madison, Wisconsin, USA 53792
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Remme CA. Cardiac sodium channelopathy associated with SCN5A mutations: electrophysiological, molecular and genetic aspects. J Physiol 2013; 591:4099-116. [PMID: 23818691 DOI: 10.1113/jphysiol.2013.256461] [Citation(s) in RCA: 121] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Over the last two decades, an increasing number of SCN5A mutations have been described in patients with long QT syndrome type 3 (LQT3), Brugada syndrome, (progressive) conduction disease, sick sinus syndrome, atrial standstill, atrial fibrillation, dilated cardiomyopathy, and sudden infant death syndrome (SIDS). Combined genetic, electrophysiological and molecular studies have provided insight into the dysfunction and dysregulation of the cardiac sodium channel in the setting of SCN5A mutations identified in patients with these inherited arrhythmia syndromes. However, risk stratification and patient management is hindered by the reduced penetrance and variable disease expressivity in sodium channelopathies. Furthermore, various SCN5A-related arrhythmia syndromes are known to display mixed phenotypes known as cardiac sodium channel overlap syndromes. Determinants of variable disease expressivity, including genetic background and environmental factors, are suspected but still largely unknown. Moreover, it has become increasingly clear that sodium channel function and regulation is more complicated than previously assumed, and the sodium channel may play additional, as of yet unrecognized, roles in cardiac structure and function. Development of cardiac structural abnormalities secondary to SCN5A mutations has been reported, but the clinical relevance and underlying mechanisms are unclear. Increased insight into these issues would enable a major next step in research related to cardiac sodium channel disease, ultimately enabling improved diagnosis, risk stratification and treatment strategies.
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Affiliation(s)
- Carol Ann Remme
- C. A. Remme: Department of Experimental Cardiology, Academic Medical Center, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands.
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38
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Defining the Pathways Underlying the Prolonged PR Interval in Atrioventricular Conduction Disease. PLoS Genet 2012; 8:e1003154. [PMID: 23236297 PMCID: PMC3516548 DOI: 10.1371/journal.pgen.1003154] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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Lodder EM, Scicluna BP, Milano A, Sun AY, Tang H, Remme CA, Moerland PD, Tanck MWT, Pitt GS, Marchuk DA, Bezzina CR. Dissection of a quantitative trait locus for PR interval duration identifies Tnni3k as a novel modulator of cardiac conduction. PLoS Genet 2012; 8:e1003113. [PMID: 23236294 PMCID: PMC3516546 DOI: 10.1371/journal.pgen.1003113] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2012] [Accepted: 10/08/2012] [Indexed: 11/23/2022] Open
Abstract
Atrio-ventricular conduction disease is a common feature in Mendelian rhythm disorders associated with sudden cardiac death and is characterized by prolongation of the PR interval on the surface electrocardiogram (ECG). Prolongation of the PR interval is also a strong predictor of atrial fibrillation, the most prevalent sustained cardiac arrhythmia. Despite the significant genetic component in PR duration variability, the genes regulating PR interval duration remain largely elusive. We here aimed to dissect the quantitative trait locus (QTL) for PR interval duration that we previously mapped in murine F2 progeny of a sensitized 129P2 and FVBN/J cross. To determine the underlying gene responsible for this QTL, genome-wide transcriptional profiling was carried out on myocardial tissue from 109 F2 mice. Expression QTLs (eQTLs) were mapped and the PR interval QTL was inspected for the co-incidence of eQTLs. We further determined the correlation of each of these transcripts to the PR interval. Tnni3k was the only eQTL, mapping to the PR-QTL, with an established abundant cardiac-specific expression pattern and a significant correlation to PR interval duration. Genotype inspection in various inbred mouse strains revealed the presence of at least three independent haplotypes at the Tnni3k locus. Measurement of PR interval duration and Tnni3k mRNA expression levels in six inbred lines identified a positive correlation between the level of Tnni3k mRNA and PR interval duration. Furthermore, in DBA/2J mice overexpressing hTNNI3K, and in DBA.AKR.hrtfm2 congenic mice, which harbor the AKR/J “high-Tnni3k expression” haplotype in the DBA/2J genetic background, PR interval duration was prolonged as compared to DBA/2J wild-type mice (“low-Tnni3k expression” haplotype). Our data provide the first evidence for a role of Tnni3k in controlling the electrocardiographic PR interval indicating a function of Tnni3k in atrio-ventricular conduction. Atrio-ventricular (AV) conduction disease (delay), characterized by prolongation of the PR interval on the surface electrocardiogram (ECG), is a common feature in Mendelian rhythm disorders and is associated with sudden cardiac death. Prolongation of the PR interval is also a strong predictor of atrial fibrillation (AF), the most common sustained cardiac arrhythmia. Although there is a substantial heritable component to the variability of the PR interval, the causative genes remain largely elusive. The identification of these genetic factors in the human population has been difficult owing to wide genetic heterogeneity and an uncontainable environment. We here exploited the homogeneous genetic background and controlled environment of inbred laboratory mouse strains to detect a genetic modifier of the PR interval. We identify Tnni3k as prime candidate for the modulation of the PR interval duration and suggest a new role for this gene, in the modulation of atrio-ventricular conduction.
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Affiliation(s)
- Elisabeth M. Lodder
- Heart Failure Research Center, Department of Experimental Cardiology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Brendon P. Scicluna
- Heart Failure Research Center, Department of Experimental Cardiology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Annalisa Milano
- Heart Failure Research Center, Department of Experimental Cardiology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Albert Y. Sun
- The Ion Channel Research Unit, Department of Medicine, Duke University, Durham, North Carolina, United States of America
| | - Hao Tang
- Department of Molecular Genetics and Microbiology, Duke University, Durham, North Carolina, United States of America
| | - Carol Ann Remme
- Heart Failure Research Center, Department of Experimental Cardiology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Perry D. Moerland
- Department of Clinical Epidemiology, Biostatistics, and Bioinformatics, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Michael W. T. Tanck
- Department of Clinical Epidemiology, Biostatistics, and Bioinformatics, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Geoffrey S. Pitt
- The Ion Channel Research Unit, Department of Medicine, Duke University, Durham, North Carolina, United States of America
| | - Douglas A. Marchuk
- Department of Molecular Genetics and Microbiology, Duke University, Durham, North Carolina, United States of America
| | - Connie R. Bezzina
- Heart Failure Research Center, Department of Experimental Cardiology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
- * E-mail:
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Abstract
PURPOSE OF REVIEW As genetic testing for long QT syndrome (LQTS) has become readily available, important advances are being made in understanding the exact link between ion channel mutation and observed phenotype. This paper reviews recent findings in the literature. RECENT FINDINGS Congenital LQTS is an important cause of sudden cardiac death. To date, 12 genes have been identified as the cause of congenital LQTS. With increasing availability of genetic testing, subtype-specific management of LQTS has become the standard of care. Detailed correlative studies between LQTS mutations and clinical phenotypes are leading the field towards 'mutation-specific' management within LQTS subtypes. A clear link between the distinct functional/biophysical defect in each LQT mutation and disease phenotype is complicated by the variable penetrance and pleiotropic expression of clinical phenotype. This is especially evident with the overlap syndrome now documented for several sodium channel (SCN5A) mutations. SUMMARY The management of LQTS has become subtype-specific due to the availability of genotype information. Review of recent literature suggests that 'mutation-specific' management is possible based upon distinct functional/biophysical characteristics of mutations within each LQT gene. Further research is required to clearly delineate the molecular and cellular mechanisms underlying variable penetrance, and pleiotropic expression of LQTS mutations.
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41
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Affiliation(s)
- Yuka Mizusawa
- Heart Failure Research Centre, Department of Clinical and Experimental Cardiology, Academic Medical Center, Amsterdam, The Netherlands
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Hoekstra M, Mummery CL, Wilde AAM, Bezzina CR, Verkerk AO. Induced pluripotent stem cell derived cardiomyocytes as models for cardiac arrhythmias. Front Physiol 2012; 3:346. [PMID: 23015789 PMCID: PMC3449331 DOI: 10.3389/fphys.2012.00346] [Citation(s) in RCA: 138] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2012] [Accepted: 08/09/2012] [Indexed: 12/20/2022] Open
Abstract
Cardiac arrhythmias are a major cause of morbidity and mortality. In younger patients, the majority of sudden cardiac deaths have an underlying Mendelian genetic cause. Over the last 15 years, enormous progress has been made in identifying the distinct clinical phenotypes and in studying the basic cellular and genetic mechanisms associated with the primary Mendelian (monogenic) arrhythmia syndromes. Investigation of the electrophysiological consequences of an ion channel mutation is ideally done in the native cardiomyocyte (CM) environment. However, the majority of such studies so far have relied on heterologous expression systems in which single ion channel genes are expressed in non-cardiac cells. In some cases, transgenic mouse models have been generated, but these also have significant shortcomings, primarily related to species differences. The discovery that somatic cells can be reprogrammed to pluripotency as induced pluripotent stem cells (iPSC) has generated much interest since it presents an opportunity to generate patient- and disease-specific cell lines from which normal and diseased human CMs can be obtained These genetically diverse human model systems can be studied in vitro and used to decipher mechanisms of disease and identify strategies and reagents for new therapies. Here, we review the present state of the art with respect to cardiac disease models already generated using IPSC technology and which have been (partially) characterized. Human iPSC (hiPSC) models have been described for the cardiac arrhythmia syndromes, including LQT1, LQT2, LQT3-Brugada Syndrome, LQT8/Timothy syndrome and catecholaminergic polymorphic ventricular tachycardia (CPVT). In most cases, the hiPSC-derived cardiomyoctes recapitulate the disease phenotype and have already provided opportunities for novel insight into cardiac pathophysiology. It is expected that the lines will be useful in the development of pharmacological agents for the management of these disorders.
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Affiliation(s)
- Maaike Hoekstra
- Department of Clinical and Experimental Cardiology, Heart Failure Research Center, Academic Medical Center, University of Amsterdam Amsterdam, Netherlands
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Verkerk AO, Remme CA, Schumacher CA, Scicluna BP, Wolswinkel R, de Jonge B, Bezzina CR, Veldkamp MW. Functional Na
V
1.8 Channels in Intracardiac Neurons. Circ Res 2012; 111:333-43. [DOI: 10.1161/circresaha.112.274035] [Citation(s) in RCA: 107] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Rationale:
The
SCN10A
gene encodes the neuronal sodium channel isoform Na
V
1.8. Several recent genome-wide association studies have linked
SCN10A
to PR interval and QRS duration, strongly suggesting an as-yet unknown role for Na
V
1.8 in cardiac electrophysiology.
Objective:
To demonstrate the functional presence of
SCN10A
/Nav1.8 in intracardiac neurons of the mouse heart.
Methods and Results:
Immunohistochemistry on mouse tissue sections showed intense Na
V
1.8 labeling in dorsal root ganglia and intracardiac ganglia and only modest Na
V
1.8 expression within the myocardium. Immunocytochemistry further revealed substantial Na
V
1.8 staining in isolated neurons from murine intracardiac ganglia but no Na
V
1.8 expression in isolated ventricular myocytes. Patch-clamp studies demonstrated that the Na
V
1.8 blocker A-803467 (0.5–2 μmol/L) had no effect on either mean sodium current (I
Na
) density or I
Na
gating kinetics in isolated myocytes but significantly reduced I
Na
density in intracardiac neurons. Furthermore, A-803467 accelerated the slow component of current decay and shifted voltage dependence of inactivation toward more negative voltages, as expected for blockade of Na
V
1.8-based I
Na
. In line with these findings, A-803467 did not affect cardiomyocyte action potential upstroke velocity but markedly reduced action potential firing frequency in intracardiac neurons, confirming a functional role for Na
V
1.8 in cardiac neural activity.
Conclusions:
Our findings demonstrate the functional presence of
SCN10A
/Na
V
1.8 in intracardiac neurons, indicating a novel role for this neuronal sodium channel in regulation of cardiac electric activity.
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Affiliation(s)
- Arie O. Verkerk
- From the Department of Clinical and Experimental Cardiology (C.A.R., C.A.S., B.P.S., R.W., C.R.B., M.W.V.) and the Department of Anatomy, Embryology, and Physiology (A.O.V., B.d.J.), Heart Failure Research Center, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Carol Ann Remme
- From the Department of Clinical and Experimental Cardiology (C.A.R., C.A.S., B.P.S., R.W., C.R.B., M.W.V.) and the Department of Anatomy, Embryology, and Physiology (A.O.V., B.d.J.), Heart Failure Research Center, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Cees A. Schumacher
- From the Department of Clinical and Experimental Cardiology (C.A.R., C.A.S., B.P.S., R.W., C.R.B., M.W.V.) and the Department of Anatomy, Embryology, and Physiology (A.O.V., B.d.J.), Heart Failure Research Center, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Brendon P. Scicluna
- From the Department of Clinical and Experimental Cardiology (C.A.R., C.A.S., B.P.S., R.W., C.R.B., M.W.V.) and the Department of Anatomy, Embryology, and Physiology (A.O.V., B.d.J.), Heart Failure Research Center, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Rianne Wolswinkel
- From the Department of Clinical and Experimental Cardiology (C.A.R., C.A.S., B.P.S., R.W., C.R.B., M.W.V.) and the Department of Anatomy, Embryology, and Physiology (A.O.V., B.d.J.), Heart Failure Research Center, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Berend de Jonge
- From the Department of Clinical and Experimental Cardiology (C.A.R., C.A.S., B.P.S., R.W., C.R.B., M.W.V.) and the Department of Anatomy, Embryology, and Physiology (A.O.V., B.d.J.), Heart Failure Research Center, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Connie R. Bezzina
- From the Department of Clinical and Experimental Cardiology (C.A.R., C.A.S., B.P.S., R.W., C.R.B., M.W.V.) and the Department of Anatomy, Embryology, and Physiology (A.O.V., B.d.J.), Heart Failure Research Center, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Marieke W. Veldkamp
- From the Department of Clinical and Experimental Cardiology (C.A.R., C.A.S., B.P.S., R.W., C.R.B., M.W.V.) and the Department of Anatomy, Embryology, and Physiology (A.O.V., B.d.J.), Heart Failure Research Center, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
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45
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Derangeon M, Montnach J, Baró I, Charpentier F. Mouse Models of SCN5A-Related Cardiac Arrhythmias. Front Physiol 2012; 3:210. [PMID: 22737129 PMCID: PMC3381239 DOI: 10.3389/fphys.2012.00210] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2012] [Accepted: 05/29/2012] [Indexed: 12/19/2022] Open
Abstract
Mutations of SCN5A gene, which encodes the α-subunit of the voltage-gated Na+ channel NaV1.5, underlie hereditary cardiac arrhythmic syndromes such as the type 3 long QT syndrome, cardiac conduction diseases, the Brugada syndrome, the sick sinus syndrome, a trial standstill, and numerous overlap syndromes. Patch-clamp studies in heterologous expression systems have provided important information to understand the genotype-phenotype relationships of these diseases. However, they could not clarify how SCN5A mutations can be responsible for such a large spectrum of diseases, for the late age of onset or the progressiveness of some of these diseases and for the overlapping syndromes. Genetically modified mice rapidly appeared as promising tools for understanding the pathophysiological mechanisms of cardiac SCN5A-related arrhythmic syndromes and several mouse models have been established. This review presents the results obtained on these models that, for most of them, recapitulate the clinical phenotypes of the patients. This includes two models knocked out for Nav1.5 β1 and β3 auxiliary subunits that are also discussed. Despite their own limitations that we point out, the mouse models still appear as powerful tools to elucidate the pathophysiological mechanisms of SCN5A-related diseases and offer the opportunity to investigate the secondary cellular consequences of SCN5A mutations such as the expression remodeling of other genes. This points out the potential role of these genes in the overall human phenotype. Finally, they constitute useful tools for addressing the role of genetic and environmental modifiers on cardiac electrical activity.
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Davis RP, Casini S, van den Berg CW, Hoekstra M, Remme CA, Dambrot C, Salvatori D, Oostwaard DWV, Wilde AAM, Bezzina CR, Verkerk AO, Freund C, Mummery CL. Cardiomyocytes derived from pluripotent stem cells recapitulate electrophysiological characteristics of an overlap syndrome of cardiac sodium channel disease. Circulation 2012; 125:3079-91. [PMID: 22647976 DOI: 10.1161/circulationaha.111.066092] [Citation(s) in RCA: 189] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
BACKGROUND Pluripotent stem cells (PSCs) offer a new paradigm for modeling genetic cardiac diseases, but it is unclear whether mouse and human PSCs can truly model both gain- and loss-of-function genetic disorders affecting the Na(+) current (I(Na)) because of the immaturity of the PSC-derived cardiomyocytes. To address this issue, we generated multiple PSC lines containing a Na(+) channel mutation causing a cardiac Na(+) channel overlap syndrome. METHOD AND RESULTS Induced PSC (iPSC) lines were generated from mice carrying the Scn5a(1798insD/+) (Scn5a-het) mutation. These mouse iPSCs, along with wild-type mouse iPSCs, were compared with the targeted mouse embryonic stem cell line used to generate the mutant mice and with the wild-type mouse embryonic stem cell line. Patch-clamp experiments showed that the Scn5a-het cardiomyocytes had a significant decrease in I(Na) density and a larger persistent I(Na) compared with Scn5a-wt cardiomyocytes. Action potential measurements showed a reduced upstroke velocity and longer action potential duration in Scn5a-het myocytes. These characteristics recapitulated findings from primary cardiomyocytes isolated directly from adult Scn5a-het mice. Finally, iPSCs were generated from a patient with the equivalent SCN5A(1795insD/+) mutation. Patch-clamp measurements on the derivative cardiomyocytes revealed changes similar to those in the mouse PSC-derived cardiomyocytes. CONCLUSION Here, we demonstrate that both embryonic stem cell- and iPSC-derived cardiomyocytes can recapitulate the characteristics of a combined gain- and loss-of-function Na(+) channel mutation and that the electrophysiological immaturity of PSC-derived cardiomyocytes does not preclude their use as an accurate model for cardiac Na(+) channel disease.
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Affiliation(s)
- Richard P Davis
- Department of Anatomy and Embryology, Leiden University Medical Center, Einthovenweg 20, 2333 ZC Leiden, The Netherlands.
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Ferreiro M, Petrosky AD, Escobar AL. Intracellular Ca2+ release underlies the development of phase 2 in mouse ventricular action potentials. Am J Physiol Heart Circ Physiol 2011; 302:H1160-72. [PMID: 22198177 DOI: 10.1152/ajpheart.00524.2011] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The ventricular action potential (AP) is characterized by a fast depolarizing phase followed by a repolarization that displays a second upstroke known as phase 2. This phase is generally not present in mouse ventricular myocytes. Thus we performed colocalized electrophysiological and optical recordings of APs in Langendorff-perfused mouse hearts founding a noticeable phase 2. Ryanodine as well as nifedipine reduced phase 2. Our hypothesis is that a depolarizing current activated by Ca(2+) released from the sarcoplasmic reticulum (SR) rather than the "electrogenicity" of the L-type Ca(2+) current is crucial in the generation of mouse ventricular phase 2. When Na(+) was partially replaced by Li(+) in the extracellular perfusate or the organ was cooled down, phase 2 was reduced. These results suggest that the Na(+)/Ca(2+) exchanger functioning in the forward mode is driving the depolarizing current that defines phase 2. Phase 2 appears to be an intrinsic characteristic of single isolated myocytes and not an emergent property of the tissue. As in whole heart experiments, ventricular myocytes impaled with microelectrodes displayed a large phase 2 that significantly increases when temperature was raised from 22 to 37°C. We conclude that mouse ventricular APs display a phase 2; however, changes in Ca(2+) dynamics and thermodynamic parameters also diminish phase 2, mostly by impairing the Na(+)/Ca(2+) exchanger. In summary, these results provide important insights about the role of Ca(2+) release in AP ventricular repolarization under physiological and pathological conditions.
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Affiliation(s)
- Marcela Ferreiro
- Biological Engineering and Small Scale Technologies Program, School of Engineering, University of California, Merced, CA 95343, USA
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Brackenbury WJ, Isom LL. Na Channel β Subunits: Overachievers of the Ion Channel Family. Front Pharmacol 2011; 2:53. [PMID: 22007171 PMCID: PMC3181431 DOI: 10.3389/fphar.2011.00053] [Citation(s) in RCA: 221] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2011] [Accepted: 09/12/2011] [Indexed: 11/13/2022] Open
Abstract
Voltage-gated Na+ channels (VGSCs) in mammals contain a pore-forming α subunit and one or more β subunits. There are five mammalian β subunits in total: β1, β1B, β2, β3, and β4, encoded by four genes: SCN1B–SCN4B. With the exception of the SCN1B splice variant, β1B, the β subunits are type I topology transmembrane proteins. In contrast, β1B lacks a transmembrane domain and is a secreted protein. A growing body of work shows that VGSC β subunits are multifunctional. While they do not form the ion channel pore, β subunits alter gating, voltage-dependence, and kinetics of VGSCα subunits and thus regulate cellular excitability in vivo. In addition to their roles in channel modulation, β subunits are members of the immunoglobulin superfamily of cell adhesion molecules and regulate cell adhesion and migration. β subunits are also substrates for sequential proteolytic cleavage by secretases. An example of the multifunctional nature of β subunits is β1, encoded by SCN1B, that plays a critical role in neuronal migration and pathfinding during brain development, and whose function is dependent on Na+ current and γ-secretase activity. Functional deletion of SCN1B results in Dravet Syndrome, a severe and intractable pediatric epileptic encephalopathy. β subunits are emerging as key players in a wide variety of physiopathologies, including epilepsy, cardiac arrhythmia, multiple sclerosis, Huntington’s disease, neuropsychiatric disorders, neuropathic and inflammatory pain, and cancer. β subunits mediate multiple signaling pathways on different timescales, regulating electrical excitability, adhesion, migration, pathfinding, and transcription. Importantly, some β subunit functions may operate independently of α subunits. Thus, β subunits perform critical roles during development and disease. As such, they may prove useful in disease diagnosis and therapy.
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Founder mutations in the Netherlands: SCN5a 1795insD, the first described arrhythmia overlap syndrome and one of the largest and best characterised families worldwide. Neth Heart J 2011; 17:422-8. [PMID: 19949711 DOI: 10.1007/bf03086296] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
In this part of a series on founder mutations in the Netherlands, we review a Dutch family carrying the SCN5a 1795insD mutation. We describe the advances in our understanding of the premature sudden cardiac deaths that have accompanied this family in the past centuries. The mutation carriers show a unique overlap of long-QT syndrome (type 3), Brugada syndrome and progressive cardiac conduction defects attributed to a single mutation in the cardiac sodium channel gene SCN5a. It is at present one of the largest and best-described families worldwide and we have learned immensely from the mouse strains with the murine homologue of the SCN5a 1795insD mutation (SCN5a 1798insD). From the studies currently performed we are about to obtain new insights into the phenotypic variability in this monogenic arrhythmia syndrome, and this might also be relevant for other arrhythmia syndromes and the general population. (Neth Heart J 2009;17:422-8.).
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