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Husti Z, Varró A, Baczkó I. Arrhythmogenic Remodeling in the Failing Heart. Cells 2021; 10:cells10113203. [PMID: 34831426 PMCID: PMC8623396 DOI: 10.3390/cells10113203] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Revised: 11/05/2021] [Accepted: 11/11/2021] [Indexed: 12/12/2022] Open
Abstract
Chronic heart failure is a clinical syndrome with multiple etiologies, associated with significant morbidity and mortality. Cardiac arrhythmias, including ventricular tachyarrhythmias and atrial fibrillation, are common in heart failure. A number of cardiac diseases including heart failure alter the expression and regulation of ion channels and transporters leading to arrhythmogenic electrical remodeling. Myocardial hypertrophy, fibrosis and scar formation are key elements of arrhythmogenic structural remodeling in heart failure. In this article, the mechanisms responsible for increased arrhythmia susceptibility as well as the underlying changes in ion channel, transporter expression and function as well as alterations in calcium handling in heart failure are discussed. Understanding the mechanisms of arrhythmogenic remodeling is key to improving arrhythmia management and the prevention of sudden cardiac death in patients with heart failure.
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Affiliation(s)
- Zoltán Husti
- Department of Pharmacology and Pharmacotherapy, University of Szeged, 6720 Szeged, Hungary; (Z.H.); (A.V.)
- Department of Pharmacology and Pharmacotherapy, Interdisciplinary Excellence Centre, University of Szeged, 6720 Szeged, Hungary
| | - András Varró
- Department of Pharmacology and Pharmacotherapy, University of Szeged, 6720 Szeged, Hungary; (Z.H.); (A.V.)
- Department of Pharmacology and Pharmacotherapy, Interdisciplinary Excellence Centre, University of Szeged, 6720 Szeged, Hungary
- ELKH-SZTE Research Group for Cardiovascular Pharmacology, Eötvös Loránd Research Network, 6720 Szeged, Hungary
| | - István Baczkó
- Department of Pharmacology and Pharmacotherapy, University of Szeged, 6720 Szeged, Hungary; (Z.H.); (A.V.)
- Department of Pharmacology and Pharmacotherapy, Interdisciplinary Excellence Centre, University of Szeged, 6720 Szeged, Hungary
- Correspondence:
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Histone deacetylase 2-dependent ventricular electrical remodeling in a porcine model of early heart failure. Life Sci 2021; 281:119769. [PMID: 34186046 DOI: 10.1016/j.lfs.2021.119769] [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: 05/11/2021] [Revised: 06/21/2021] [Accepted: 06/23/2021] [Indexed: 12/29/2022]
Abstract
AIMS Heart failure (HF) is linked to electrical remodeling that promotes ventricular arrhythmias. Underlying molecular signaling is insufficiently understood, in particular concerning patients with early disease stages. Previous observations suggest a key role for epigenetic mechanisms in cardiac remodeling processes. We hypothesized that histone deacetylases (HDACs) 1 and 2 contribute to cellular electrophysiological dysregulation in ventricular cardiomyocytes during HF development. MATERIALS AND METHODS HDAC and ion channel expression was quantified in a porcine model of early HF induced by short-term atrial tachypacing, resulting in atrial fibrillation with rapid ventricular rate response. Anti-Hdac1 and anti-Hdac2 siRNA treatment was employed in neonatal murine cardiomyocytes (NMCM) to study effects of HDACs on ion channel mRNA expression and action potential duration (APD). KEY FINDINGS Early HF was characterized by mild reduction of left ventricular ejection fraction, prolonged QTc intervals, and increased ventricular effective refractory periods. Delayed repolarization was linked to significant downregulation of HDAC2 in left ventricular (LV) tissue. In addition, there was a tendency towards reduced transcript expression of KCNJ2/Kir2.1 K+ channels. In NMCM, knock-down of Hdac2 recapitulated AP prolongation. Finally, siRNA-mediated suppression of Hdac2 reduced Kcnh2/Kv11.1 K+ channel expression. SIGNIFICANCE Suppression of HDAC2 is linked to ventricular electrical remodeling of APD and ion channel expression in early stages of heart failure. This previously unrecognized mechanism may serve as basis for future approaches to prevention and treatment of ventricular arrhythmias.
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Shugg T, Hudmon A, Overholser BR. Neurohormonal Regulation of I Ks in Heart Failure: Implications for Ventricular Arrhythmogenesis and Sudden Cardiac Death. J Am Heart Assoc 2020; 9:e016900. [PMID: 32865116 PMCID: PMC7726975 DOI: 10.1161/jaha.120.016900] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Heart failure (HF) results in sustained alterations in neurohormonal signaling, including enhanced signaling through the sympathetic nervous system and renin-angiotensin-aldosterone system pathways. While enhanced sympathetic nervous system and renin-angiotensin-aldosterone system activity initially help compensate for the failing myocardium, sustained signaling through these pathways ultimately contributes to HF pathophysiology. HF remains a leading cause of mortality, with arrhythmogenic sudden cardiac death comprising a common mechanism of HF-related death. The propensity for arrhythmia development in HF occurs secondary to cardiac electrical remodeling that involves pathological regulation of ventricular ion channels, including the slow component of the delayed rectifier potassium current, that contribute to action potential duration prolongation. To elucidate a mechanistic explanation for how HF-mediated electrical remodeling predisposes to arrhythmia development, a multitude of investigations have investigated the specific regulatory effects of HF-associated stimuli, including enhanced sympathetic nervous system and renin-angiotensin-aldosterone system signaling, on the slow component of the delayed rectifier potassium current. The objective of this review is to summarize the current knowledge related to the regulation of the slow component of the delayed rectifier potassium current in response to HF-associated stimuli, including the intracellular pathways involved and the specific regulatory mechanisms.
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Affiliation(s)
- Tyler Shugg
- Division of Clinical PharmacologyIndiana University School of MedicineIndianapolisIN
| | - Andy Hudmon
- Department of Medicinal Chemistry and Molecular PharmacologyPurdue University College of PharmacyWest LafayetteIN
| | - Brian R. Overholser
- Division of Clinical PharmacologyIndiana University School of MedicineIndianapolisIN
- Department of Pharmacy PracticePurdue University College of PharmacyIndianapolisIN
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4
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Benz A, Kossack M, Auth D, Seyler C, Zitron E, Juergensen L, Katus HA, Hassel D. miR-19b Regulates Ventricular Action Potential Duration in Zebrafish. Sci Rep 2016; 6:36033. [PMID: 27805004 PMCID: PMC5090966 DOI: 10.1038/srep36033] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Accepted: 10/10/2016] [Indexed: 01/03/2023] Open
Abstract
Sudden cardiac death due to ventricular arrhythmias often caused by action potential duration (APD) prolongation is a common mode of death in heart failure (HF). microRNAs, noncoding RNAs that fine tune gene expression, are frequently dysregulated during HF, suggesting a potential involvement in the electrical remodeling process accompanying HF progression. Here, we identified miR-19b as an important regulator of heart function. Zebrafish lacking miR-19b developed severe bradycardia and reduced cardiac contractility. miR-19b deficient fish displayed increased sensitivity to AV-block, a characteristic feature of long QT syndrome in zebrafish. Patch clamp experiments from whole hearts showed that miR-19b deficient zebrafish exhibit significantly prolonged ventricular APD caused by impaired repolarization. We found that miR-19b directly and indirectly regulates the expression of crucial modulatory subunits of cardiac ion channels, and thereby modulates AP duration and shape. Interestingly, miR-19b knockdown mediated APD prolongation can rescue a genetically induced short QT phenotype. Thus, miR-19b might represent a crucial modifier of the cardiac electrical activity, and our work establishes miR-19b as a potential candidate for human long QT syndrome.
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Affiliation(s)
- Alexander Benz
- Department of Medicine III, Cardiology, Angiology and Pneumology, University Hospital of Heidelberg, 69120 Heidelberg, Germany.,DZHK (German Centre for Cardiovascular Research), Partner Site Heidelberg/Mannheim, 69120 Heidelberg, Germany
| | - Mandy Kossack
- Department of Medicine III, Cardiology, Angiology and Pneumology, University Hospital of Heidelberg, 69120 Heidelberg, Germany.,DZHK (German Centre for Cardiovascular Research), Partner Site Heidelberg/Mannheim, 69120 Heidelberg, Germany
| | - Dominik Auth
- Department of Medicine III, Cardiology, Angiology and Pneumology, University Hospital of Heidelberg, 69120 Heidelberg, Germany
| | - Claudia Seyler
- Department of Medicine III, Cardiology, Angiology and Pneumology, University Hospital of Heidelberg, 69120 Heidelberg, Germany.,DZHK (German Centre for Cardiovascular Research), Partner Site Heidelberg/Mannheim, 69120 Heidelberg, Germany
| | - Edgar Zitron
- Department of Medicine III, Cardiology, Angiology and Pneumology, University Hospital of Heidelberg, 69120 Heidelberg, Germany.,DZHK (German Centre for Cardiovascular Research), Partner Site Heidelberg/Mannheim, 69120 Heidelberg, Germany
| | - Lonny Juergensen
- Department of Medicine III, Cardiology, Angiology and Pneumology, University Hospital of Heidelberg, 69120 Heidelberg, Germany.,DZHK (German Centre for Cardiovascular Research), Partner Site Heidelberg/Mannheim, 69120 Heidelberg, Germany
| | - Hugo A Katus
- Department of Medicine III, Cardiology, Angiology and Pneumology, University Hospital of Heidelberg, 69120 Heidelberg, Germany.,DZHK (German Centre for Cardiovascular Research), Partner Site Heidelberg/Mannheim, 69120 Heidelberg, Germany
| | - David Hassel
- Department of Medicine III, Cardiology, Angiology and Pneumology, University Hospital of Heidelberg, 69120 Heidelberg, Germany.,DZHK (German Centre for Cardiovascular Research), Partner Site Heidelberg/Mannheim, 69120 Heidelberg, Germany
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5
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Gloschat CR, Koppel AC, Aras KK, Brennan JA, Holzem KM, Efimov IR. Arrhythmogenic and metabolic remodelling of failing human heart. J Physiol 2016; 594:3963-80. [PMID: 27019074 DOI: 10.1113/jp271992] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Accepted: 03/21/2016] [Indexed: 12/24/2022] Open
Abstract
Heart failure (HF) is a major cause of morbidity and mortality worldwide. The global burden of HF continues to rise, with prevalence rates estimated at 1-2% and incidence approaching 5-10 per 1000 persons annually. The complex pathophysiology of HF impacts virtually all aspects of normal cardiac function - from structure and mechanics to metabolism and electrophysiology - leading to impaired mechanical contraction and sudden cardiac death. Pharmacotherapy and device therapy are the primary methods of treating HF, but neither is able to stop or reverse disease progression. Thus, there is an acute need to translate basic research into improved HF therapy. Animal model investigations are a critical component of HF research. However, the translation from cellular and animal models to the bedside is hampered by significant differences between species and among physiological scales. Our studies over the last 8 years show that hypotheses generated in animal models need to be validated in human in vitro models. Importantly, however, human heart investigations can establish translational platforms for safety and efficacy studies before embarking on costly and risky clinical trials. This review summarizes recent developments in human HF investigations of electrophysiology remodelling, metabolic remodelling, and β-adrenergic remodelling and discusses promising new technologies for HF research.
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Affiliation(s)
- C R Gloschat
- Department of Biomedical Engineering, The George Washington University, Washington, DC, USA
| | - A C Koppel
- Department of Biomedical Engineering, The George Washington University, Washington, DC, USA
| | - K K Aras
- Department of Biomedical Engineering, The George Washington University, Washington, DC, USA
| | - J A Brennan
- Department of Biomedical Engineering, The George Washington University, Washington, DC, USA
| | - K M Holzem
- Department of Biomedical Engineering, The George Washington University, Washington, DC, USA
| | - I R Efimov
- Department of Biomedical Engineering, The George Washington University, Washington, DC, USA
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6
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Patel PJ, Borovskiy Y, Killian A, Verdino RJ, Epstein AE, Callans DJ, Marchlinski FE, Deo R. Optimal QT interval correction formula in sinus tachycardia for identifying cardiovascular and mortality risk: Findings from the Penn Atrial Fibrillation Free study. Heart Rhythm 2015; 13:527-35. [PMID: 26552754 DOI: 10.1016/j.hrthm.2015.11.008] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2015] [Indexed: 11/19/2022]
Abstract
BACKGROUND The QT interval measures cardiac repolarization, and prolongation is associated with adverse cardiovascular outcomes and death. The exponential Bazett correction formula overestimates the QT interval during tachycardia. OBJECTIVE We evaluated 4 formulas of QT interval correction in individuals with sinus tachycardia for the identification of coronary artery disease, heart failure, and mortality. METHODS The Penn Atrial Fibrillation Free study is a large cohort study of patients without atrial fibrillation. The present study examined 6723 Penn Atrial Fibrillation Free study patients without a history of heart failure and with baseline sinus rate ≥100 beats/min. Medical records were queried for index clinical parameters, incident cardiovascular events, and all-cause mortality. The QT interval was corrected by using Bazett (QT/RR(0.5)), Fridericia (QT/RR(0.33)), Framingham [QT + 0.154 * (1000 - RR)], and Hodges (QT + 105 * (1/RR - 1)) formulas. RESULTS In 6723 patients with a median follow-up of 4.5 years (interquartile range 1.9-6.4 years), the annualized cardiovascular event rate was 2.3% and the annualized mortality rate was 2.2%. QT prolongation was diagnosed in 39% of the cohort using the Bazett formula, 6.2% using the Fridericia formula, 3.7% using the Framingham formula, and 8.7% using the Hodges formula. Only the Hodges formula was an independent risk marker for death across the range of QT values (highest tertile: hazard ratio 1.26; 95% confidence interval 1.03-1.55). CONCLUSION Although all correction formulas demonstrated an association between QTc values and cardiovascular events, only the Hodges formula identified one-third of individuals with tachycardia that are at higher risk of all-cause mortality. Furthermore, the Bazett correction formula overestimates the number of patients with a prolonged QT interval and was not associated with mortality. Future work may validate these findings and result in changes to automated algorithms for QT interval assessment.
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Affiliation(s)
- Parin J Patel
- St. Vincent Medical Group, Division of Cardiology, Indianapolis, Indiana; Section of Electrophysiology, Division of Cardiovascular Medicine, University of Pennsylvania, Philadelphia, Pennsylvania.
| | - Yuliya Borovskiy
- Section of Electrophysiology, Division of Cardiovascular Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Anthony Killian
- Section of Electrophysiology, Division of Cardiovascular Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Ralph J Verdino
- Section of Electrophysiology, Division of Cardiovascular Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Andrew E Epstein
- Section of Electrophysiology, Division of Cardiovascular Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - David J Callans
- Section of Electrophysiology, Division of Cardiovascular Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Francis E Marchlinski
- Section of Electrophysiology, Division of Cardiovascular Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Rajat Deo
- Section of Electrophysiology, Division of Cardiovascular Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
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7
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Abstract
Optimal cardiac function depends on proper timing of excitation and contraction in various regions of the heart, as well as on appropriate heart rate. This is accomplished via specialized electrical properties of various components of the system, including the sinoatrial node, atria, atrioventricular node, His-Purkinje system, and ventricles. Here we review the major regionally determined electrical properties of these cardiac regions and present the available data regarding the molecular and ionic bases of regional cardiac function and dysfunction. Understanding these differences is of fundamental importance for the investigation of arrhythmia mechanisms and pharmacotherapy.
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Affiliation(s)
- Daniel C Bartos
- Department of Pharmacology, University of California Davis, Davis, California, USA
| | - Eleonora Grandi
- Department of Pharmacology, University of California Davis, Davis, California, USA
| | - Crystal M Ripplinger
- Department of Pharmacology, University of California Davis, Davis, California, USA
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8
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Elshrif MM, Shi P, Cherry EM. Representing variability and transmural differences in a model of human heart failure. IEEE J Biomed Health Inform 2015; 19:1308-20. [PMID: 26068919 DOI: 10.1109/jbhi.2015.2442833] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
During heart failure (HF) at the cellular level, the electrophysiological properties of single myocytes get remodeled, which can trigger the occurrence of ventricular arrhythmias that could be manifested in many forms such as early afterdepolarizations (EADs) and alternans (ALTs). In this paper, based on experimentally observed human HF data, specific ionic and exchanger current strengths are modified from a recently developed human ventricular cell model: the O'Hara-Virág-Varró-Rudy (OVVR) model. A new transmural HF-OVVR model is developed that incorporates HF changes and variability of the observed remodeling. This new heterogeneous HF-OVVR model is able to replicate many of the failing action potential (AP) properties and the dynamics of both [Ca(2+)]i and [Na(+)]i in accordance with experimental data. Moreover, it is able to generate EADs for different cell types and exhibits ALTs at modest pacing rate for transmural cell types. We have assessed the HF-OVVR model through the examination of the AP duration and the major ionic currents' rate dependence in single myocytes. The evaluation of the model comes from utilizing the steady-state (S-S) and S1-S2 restitution curves and from probing the accommodation of the HF-OVVR model to an abrupt change in cycle length. In addition, we have investigated the effect of chosen currents on the AP properties, such as blocking the slow sodium current to shorten the AP duration and suppress the EADs, and have found good agreement with experimental observations. This study should help elucidate arrhythmogenic mechanisms at the cellular level and predict unseen properties under HF conditions. In addition, this AP cell model might be useful for modeling and simulating HF at the tissue and organ levels.
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9
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Holzem KM, Efimov IR. Arrhythmogenic remodelling of activation and repolarization in the failing human heart. Europace 2013; 14 Suppl 5:v50-v57. [PMID: 23104915 DOI: 10.1093/europace/eus275] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Heart failure is a major cause of disability and death worldwide, and approximately half of heart failure-related deaths are sudden and presumably due to ventricular arrhythmias. Patients with heart failure have been shown to be at 6- to 9-fold increased risk of sudden cardiac death compared to the general population. (AHA. Heart Disease and Stroke Statistics-2003 Update. Heart and Stroke Facts. Dallas, TX: American Heart Association; 2002) Thus, electrophysiological remodelling associated with heart failure is a leading cause of disease mortality and has been a major investigational focus examined using many animal models of heart failure. While these studies have provided an important foundation for understanding the arrhythmogenic pathophysiology of heart failure, the need for corroborating studies conducted on human heart tissue has been increasingly recognized. Many human heart studies of conduction and repolarization remodelling have now been published and shed some light on important, potentially arrhythmogenic, changes in human heart failure. These studies are being conducted at multiple experimental scales from isolated cells to whole-tissue preparations and have provided insight into regulatory mechanisms such as decreased protein expression, alternative mRNA splicing of ion channel genes, and defective cellular trafficking. Further investigations of heart failure in the human myocardium will be essential for determining possible therapeutic targets to prevent arrhythmia in heart failure and for facilitating the translation of basic research findings to the clinical realm.
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Affiliation(s)
- Katherine M Holzem
- Department of Biomedical Engineering, Washington University in St Louis, One Brookings Drive, St Louis, MO 63130, USA
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10
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Yoshizawa A, Nagai S, Baba Y, Yamada T, Matsui M, Tanaka H, Miyoshi SI, Amagai M, Yoshikawa T, Fukuda K, Ogawa S, Koyasu S. Autoimmunity against M2muscarinic acetylcholine receptor induces myocarditis and leads to a dilated cardiomyopathy-like phenotype. Eur J Immunol 2012; 42:1152-63. [DOI: 10.1002/eji.201142104] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Akihiro Yoshizawa
- Department of Microbiology and Immunology, Keio University School of Medicine; Tokyo Japan
- Department of Cardiology; Keio University School of Medicine; Tokyo Japan
- Tokyo Dental College Ichikawa Hospital; Ichikawa Japan
| | - Shigenori Nagai
- Department of Microbiology and Immunology, Keio University School of Medicine; Tokyo Japan
- Core Research for Evolutional Science and Technology, Japan Science and Technology Agency; Tokyo Japan
| | - Yukiko Baba
- Department of Microbiology and Immunology, Keio University School of Medicine; Tokyo Japan
- Core Research for Evolutional Science and Technology, Japan Science and Technology Agency; Tokyo Japan
| | - Taketo Yamada
- Department of Pathology; Keio University School of Medicine; Tokyo Japan
| | - Minoru Matsui
- Department of Pharmacy; Chiba Institute of Science; Chiba Japan
| | - Hikaru Tanaka
- Department of Pharmacology; Toho University Faculty of Pharmaceutical Sciences; Chiba Japan
| | | | - Masayuki Amagai
- Department of Dermatology; Keio University School of Medicine; Tokyo Japan
| | - Tsutomu Yoshikawa
- Department of Cardiology; Keio University School of Medicine; Tokyo Japan
| | - Keiichi Fukuda
- Department of Cardiology; Keio University School of Medicine; Tokyo Japan
| | - Satoshi Ogawa
- Department of Cardiology; Keio University School of Medicine; Tokyo Japan
| | - Shigeo Koyasu
- Department of Microbiology and Immunology, Keio University School of Medicine; Tokyo Japan
- Research Center for Science Systems, Japan Society for the Promotion of Science; Tokyo Japan
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11
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Wang K, Terrenoire C, Sampson KJ, Iyer V, Osteen JD, Lu J, Keller G, Kotton DN, Kass RS. Biophysical properties of slow potassium channels in human embryonic stem cell derived cardiomyocytes implicate subunit stoichiometry. J Physiol 2011; 589:6093-104. [PMID: 22025662 DOI: 10.1113/jphysiol.2011.220863] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Human embryonic stem cells (hESCs) are an important cellular model for studying ion channel function in the context of a human cardiac cell and will provide a wealth of information about both heritable arrhythmias and acquired electrophysiological disorders. However, detailed electrophysiological characterization of the important cardiac ion channels has been so far overlooked. Because mutations in the gene for the I(Ks) α subunit, KCNQ1, constitute the majority of long QT syndrome (LQT-1) cases, we have carried out a detailed biophysical analysis of this channel expressed in hESCs to establish baseline I(Ks) channel biophysical properties in cardiac myocytes derived from hESCs (hESC-CMs). I(Ks) channels are heteromultimeric proteins consisting of four identical α-subunits (KCNQ1) assembled with auxiliary β-subunits (KCNE1). We found that the half-maximal I(Ks) activation voltage in hESC-CMs and in myocytes derived from human induced pluripotent stems cells (hiPSC-CMs) falls between that of KCNQ1 channels expressed alone and with full complement of KCNE1, the major KCNE subunit expressed in hESC-CMs as shown by qPCR analysis. Overexpression of KCNE1 by transfection of hESC-CMs markedly shifted and slowed native I(Ks) activation implying assembly of additional KCNE1 subunits with endogenous channels. Our results in hESC-CMs, which indicate an I(Ks) subunit stoichiometry that can be altered by variable KCNE1 expression, suggest the possibility for variable I(Ks) function in the developing heart, in different tissues in the heart, and in disease. This establishes a new baseline for I(Ks) channel properties in myocytes derived from pluripotent stem cells and will guide future studies in patient-specific hiPSCs.
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Affiliation(s)
- Kai Wang
- Department of Pharmacology, College of Physicians and Surgeons, Columbia University Medical Center, New York, NY 10032, USA
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12
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Affiliation(s)
- T Jespersen
- Department of Biomedical Sciences 16.5, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
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13
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Soltysinska E, Olesen SP, Christ T, Wettwer E, Varró A, Grunnet M, Jespersen T. Transmural expression of ion channels and transporters in human nondiseased and end-stage failing hearts. Pflugers Arch 2010; 459:11-23. [PMID: 19768467 DOI: 10.1007/s00424-009-0718-3] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2009] [Revised: 07/27/2009] [Accepted: 08/21/2009] [Indexed: 02/02/2023]
Abstract
The cardiac action potential is primarily shaped by the orchestrated function of several different types of ion channels and transporters. One of the regional differences believed to play a major role in the progression and stability of the action potential is the transmural gradient of electrical activity across the ventricular wall. An altered balance in the ionic currents across the free wall is assumed to be a substrate for arrhythmia. A large fraction of patients with heart failure experience ventricular arrhythmia. However, the underlying substrate of these functional changes is not well-established as expression analyses of human heart failure (HF) are sparse. We have investigated steady-state RNA levels by quantitative polymerase chain reaction of ion channels, transporters, connexin 43, and miR-1 in 11 end-stage HF and seven nonfailing (NF) hearts. The quantifications were performed on endo-, mid-, and epicardium of left ventricle, enabling us to establish changes in the transmural expression gradient. Transcripts encoding Cav1.2, HCN2, Kir2.1, KCNE1, SUR1, and NCX1 were upregulated in HF compared to NF while a downregulation was observed for KChIP2, SERCA2, and miR-1. Additionally, the transmural gradient of KCNE1, KChIP2, Kir6.2, SUR1, Nav1.5, NCX1, and RyR2 found in NF was only preserved for KChiP2 and Nav1.5 in HF. The transmural gradients of NCX1, Nav1.5, and KChIP2 and the downregulation of KChIP2 were confirmed by Western blotting. In conclusion, our results reveal altered expression of several cardiac ion channels and transporters which may in part explain the increased susceptibility to arrhythmia in end-state failing hearts.
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Affiliation(s)
- Ewa Soltysinska
- The Danish National Research Foundation Centre for Cardiac Arrhythmia (DARC), Department of Biomedical Sciences, Faculty of Health Sciences, University of Copenhagen, Blegdamsvej 3, 2200 Copenhagen N, Denmark
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14
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Fatini C, Sticchi E, Marcucci R, Verdiani V, Nozzoli C, Vassallo C, Emdin M, Abbate R, Gensini GF. S38G single-nucleotide polymorphism at the KCNE1 locus is associated with heart failure. Heart Rhythm 2009; 7:363-7. [PMID: 20185111 DOI: 10.1016/j.hrthm.2009.11.032] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/19/2009] [Accepted: 11/29/2009] [Indexed: 11/26/2022]
Abstract
BACKGROUND Prolongation of the action potential duration, whose major determinants are the delayed-rectifier potassium currents, is a hallmark of failing ventricular myocardium. Genetic variants in the KCNE1 gene, encoding for the beta-subunit (minK) of a slowly activated cardiac potassium channel (I(ks)), may impair myocardial repolarization. Experimental data demonstrated a higher KCNE1 expression in heart failure (HF). OBJECTIVE The purpose of this study was to investigate the association between a KCNE1 S38G single-nucleotide polymorphism (SNP) and HF. METHODS We genotyped 197 out of 323 previously investigated patients and 352 healthy controls comparable for age and sex. This study was replicated in 186 HF patients and in 200 healthy subjects comparable for age and sex and recruited from the Department of Cardiovascular Medicine of the National Research Council, Pisa, Italy. RESULTS A significant difference in genotype distribution and allele frequency between patients and controls was observed for the KCNE1 S38G SNP (P = .002 and P = .0008, respectively). The KCNE1 38G variant was associated with a significant predisposition to HF under a dominant (odds ratio [OR] = 2.22 [1.23-3.28]; P = .008) and additive (OR = 2.13 [1.09-4.15]; P = .03) model, after adjustment for age, sex, and traditional cardiovascular risk factors. No difference in genotype distribution and allele frequency for the KCNE1 S38G SNP according to functional New York Heart Association class was found (P = .4 and P = .3, respectively). In the HF replication study, the KCNE1 38G allele frequency was significantly higher in comparison with that observed in the control population (38G = 0.59 vs. 0.49; P = .004). The 38G allele was associated with HF predisposition under the recessive (OR [95% confidence interval (CI)] = 2.49 [1.45-4.29]; P = .001) and additive models (OR [95% CI] = 2.63 [1.29-5.35]; P = .008), after adjustment for traditional risk factors. CONCLUSION KCNE1 S38G SNP is associated with HF predisposition in two study populations. Nevertheless, further studies performed in larger populations and aimed to better define the role of this locus are required.
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Affiliation(s)
- Cinzia Fatini
- Department of Medical and Surgical Critical Care, University of Florence, Florence, Italy.
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Lehtinen AB, Daniel KR, Shah SA, Nelson MR, Ziegler JT, Freedman BI, Carr JJ, Herrington DM, Langefeld CD, Bowden DW. Relationship between genetic variants in myocardial sodium and potassium channel genes and QT interval duration in diabetics: the Diabetes Heart Study. Ann Noninvasive Electrocardiol 2009; 14:72-9. [PMID: 19149796 DOI: 10.1111/j.1542-474x.2008.00276.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND Genetic variants in myocardial sodium and potassium channel genes are associated with prolonged QT interval and increased risk of sudden death. It is unclear whether these genetic variants remain relevant in subjects with underlying conditions such as diabetes that are associated with prolonged QT interval. METHODS We tested single nucleotide polymorphisms (SNPs) in five candidate genes for association with QT interval in a family-based study of subjects with type 2 diabetes mellitus (T2DM). Thirty-six previously reported SNPs were genotyped in KCNQ1, HERG, SCN5A, KCNE1, and KCNE2 in 901 European Americans from 366 families. The heart rate-corrected (QTc) durations were determined using the Marquette 12SL program. Associations between the QTc interval and the genotypes were evaluated using SOLAR adjusting for age, gender, T2DM status, and body mass index. RESULTS Within KCNQ1 there was weak evidence for association between the minor allele of IVS12 +14T>C and increased QTc (P = 0.02). The minor allele of rs2236609 in KCNE1 trended toward significance with longer QTc (P = 0.06), while the minor allele of rs1805123 in HERG trended toward significance with shorter QTc (P = 0.07). However, no statistically significant associations were observed between the remaining SNPs and QTc variation. CONCLUSIONS We found weak evidence of association between three previously reported SNPs and QTc interval duration. While it appears as though genetic variants in previously identified candidate genes may be associated with QT duration in subjects with diabetes, the clinical implications of these associations in diabetic subjects at high risk for sudden death remain to be determined.
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Affiliation(s)
- Allison B Lehtinen
- Department of Biochemistry, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27157, USA
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Poulsen AN, Klaerke DA. The KCNE1 beta-subunit exerts a transient effect on the KCNQ1 K+ channel. Biochem Biophys Res Commun 2007; 363:133-9. [PMID: 17845799 DOI: 10.1016/j.bbrc.2007.08.146] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2007] [Accepted: 08/21/2007] [Indexed: 11/23/2022]
Abstract
The KCNE1 beta-subunit is a modulatory one-trans-membrane segment accessory protein that alters KCNQ1 K(+) channel current characteristics, though it is not required for channel expression. The KCNE1 and KCNQ1 interaction was investigated by looking for effects of expression time on channel currents in Xenopus laevis oocytes. We found that long-time expression of KCNQ1+KCNE1 (2-14 days) resulted in gradual changes in current characteristics resembling a disappearance of KCNE1 from the oocyte plasma membrane. Towards the end of the expression period the current of oocytes expressing KCNQ1+KCNE1 was indistinguishable from those expressing KCNQ1 alone. No time dependent effect was seen in oocytes expressing KCNQ1 alone or a concatamer of KCNQ1 and KCNE1. Brefeldin A was tested, showing that measured current was independent of exocytosis (decreased capacitance) thus eliminating a continuous displacement-explanation. Based on the functional data, we suggest that the interaction between KNCE1 and KCNQ1 may be reversible and transient in a "Kiss & Go" manner, supporting a physiological role for KCNE1 as a dynamic regulatory molecule.
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Affiliation(s)
- Asser Nyander Poulsen
- Department of Physiology and Biochemistry, IBHV, Faculty of Life Sciences, University of Copenhagen, Groennegaardsvej 7, 1870 Frederiksberg C, Denmark.
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