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Zhong Z, Li X, Gao L, Wu X, Ye Y, Zhang X, Zeng Q, Zhou C, Lu X, Wei Y, Ding Y, Chen S, Zhou G, Xu J, Liu S. Long Non-coding RNA Involved in the Pathophysiology of Atrial Fibrillation. Cardiovasc Drugs Ther 2023:10.1007/s10557-023-07491-8. [PMID: 37702834 DOI: 10.1007/s10557-023-07491-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 07/12/2023] [Indexed: 09/14/2023]
Abstract
BACKGROUND Atrial fibrillation (AF) is a prevalent and chronic cardiovascular disorder associated with various pathophysiological alterations, including atrial electrical and structural remodeling, disrupted calcium handling, autonomic nervous system dysfunction, aberrant energy metabolism, and immune dysregulation. Emerging evidence suggests that long non-coding RNAs (lncRNAs) play a significant role in the pathogenesis of AF. OBJECTIVE This discussion aims to elucidate the involvement of AF-related lncRNAs, with a specific focus on their role as miRNA sponges that modulate crucial signaling pathways, contributing to the progression of AF. We also address current limitations in AF-related lncRNA research and explore potential future directions in this field. Additionally, we summarize feasible strategies and promising delivery systems for targeting lncRNAs in AF therapy. CONCLUSION In conclusion, targeting AF-related lncRNAs holds substantial promise for future investigations and represents a potential therapeutic avenue for managing AF.
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Affiliation(s)
- Zikan Zhong
- Department of Cardiology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Xintao Li
- Department of Cardiology, The First Affiliated Hospital of Soochow University, Suzhou, Jiangsu, China
| | - Longzhe Gao
- Department of Cardiology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Xiaoyu Wu
- Department of Cardiology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yutong Ye
- Department of Cardiology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Xiaoyu Zhang
- Department of Cardiology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Qingye Zeng
- Department of Cardiology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Changzuan Zhou
- Department of Cardiology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Xiaofeng Lu
- Department of Cardiology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yong Wei
- Department of Cardiology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yu Ding
- Department of Cardiology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Songwen Chen
- Department of Cardiology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Genqing Zhou
- Department of Cardiology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
| | - Juan Xu
- Department of Cardiology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
| | - Shaowen Liu
- Department of Cardiology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
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Telle Å, Bargellini C, Chahine Y, Del Álamo JC, Akoum N, Boyle PM. Personalized biomechanical insights in atrial fibrillation: opportunities & challenges. Expert Rev Cardiovasc Ther 2023; 21:817-837. [PMID: 37878350 PMCID: PMC10841537 DOI: 10.1080/14779072.2023.2273896] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/12/2023] [Accepted: 10/18/2023] [Indexed: 10/26/2023]
Abstract
INTRODUCTION Atrial fibrillation (AF) is an increasingly prevalent and significant worldwide health problem. Manifested as an irregular atrial electrophysiological activation, it is associated with many serious health complications. AF affects the biomechanical function of the heart as contraction follows the electrical activation, subsequently leading to reduced blood flow. The underlying mechanisms behind AF are not fully understood, but it is known that AF is highly correlated with the presence of atrial fibrosis, and with a manifold increase in risk of stroke. AREAS COVERED In this review, we focus on biomechanical aspects in atrial fibrillation, current and emerging use of clinical images, and personalized computational models. We also discuss how these can be used to provide patient-specific care. EXPERT OPINION Understanding the connection betweenatrial fibrillation and atrial remodeling might lead to valuable understanding of stroke and heart failure pathophysiology. Established and emerging imaging modalities can bring us closer to this understanding, especially with continued advancements in processing accuracy, reproducibility, and clinical relevance of the associated technologies. Computational models of cardiac electromechanics can be used to glean additional insights on the roles of AF and remodeling in heart function.
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Affiliation(s)
- Åshild Telle
- Department of Bioengineering, University of Washington, Seattle, WA, USA
| | - Clarissa Bargellini
- Department of Mechanical Engineering, University of Washington, Seattle, WA, USA
| | - Yaacoub Chahine
- Division of Cardiology, University of Washington, Seattle, WA, USA
| | - Juan C Del Álamo
- Department of Mechanical Engineering, University of Washington, Seattle, WA, USA
- Center for Cardiovascular Biology, University of Washington, Seattle, WA, USA
| | - Nazem Akoum
- Department of Bioengineering, University of Washington, Seattle, WA, USA
- Division of Cardiology, University of Washington, Seattle, WA, USA
| | - Patrick M Boyle
- Department of Bioengineering, University of Washington, Seattle, WA, USA
- Center for Cardiovascular Biology, University of Washington, Seattle, WA, USA
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA, USA
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3
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Godoy-Marín H, Jiménez-Sábado V, Tarifa C, Ginel A, Santos JLD, Bentzen BH, Hove-Madsen L, Ciruela F. Increased Density of Endogenous Adenosine A 2A Receptors in Atrial Fibrillation: From Cellular and Porcine Models to Human Patients. Int J Mol Sci 2023; 24:ijms24043668. [PMID: 36835078 PMCID: PMC9963500 DOI: 10.3390/ijms24043668] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2023] [Revised: 02/04/2023] [Accepted: 02/09/2023] [Indexed: 02/17/2023] Open
Abstract
Adenosine, an endogenous nucleoside, plays a critical role in maintaining homeostasis during stressful situations, such as energy deprivation or cellular damage. Therefore, extracellular adenosine is generated locally in tissues under conditions such as hypoxia, ischemia, or inflammation. In fact, plasma levels of adenosine in patients with atrial fibrillation (AF) are elevated, which also correlates with an increased density of adenosine A2A receptors (A2ARs) both in the right atrium and in peripheral blood mononuclear cells (PBMCs). The complexity of adenosine-mediated effects in health and disease requires simple and reproducible experimental models of AF. Here, we generate two AF models, namely the cardiomyocyte cell line HL-1 submitted to Anemonia toxin II (ATX-II) and a large animal model of AF, the right atrium tachypaced pig (A-TP). We evaluated the density of endogenous A2AR in those AF models. Treatment of HL-1 cells with ATX-II reduced cell viability, while the density of A2AR increased significantly, as previously observed in cardiomyocytes with AF. Next, we generated the animal model of AF based on tachypacing pigs. In particular, the density of the key calcium regulatory protein calsequestrin-2 was reduced in A-TP animals, which is consistent with the atrial remodelling shown in humans suffering from AF. Likewise, the density of A2AR in the atrium of the AF pig model increased significantly, as also shown in the biopsies of the right atrium of subjects with AF. Overall, our findings revealed that these two experimental models of AF mimicked the alterations in A2AR density observed in patients with AF, making them attractive models for studying the adenosinergic system in AF.
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Affiliation(s)
- Héctor Godoy-Marín
- Pharmacology Unit, Department of Pathology and Experimental Therapeutics, School of Medicine and Health Sciences, Institute of Neurosciences, University of Barcelona, 08907 L’Hospitalet de Llobregat, Spain
- Neuropharmacology & Pain Group, Neuroscience Program, Bellvitge Institute for Biomedical Research, 08907 L’Hospitalet de Llobregat, Spain
| | - Verónica Jiménez-Sábado
- Biomedical Research Institute Sant Pau, IIB Sant Pau, 08025 Barcelona, Spain
- Centro de Investigación Biomédica en Red Enfermedades Cardiovasculares, 28029 Madrid, Spain
| | - Carmen Tarifa
- Biomedical Research Institute Sant Pau, IIB Sant Pau, 08025 Barcelona, Spain
- Biomedical Research Institute of Barcelona, IIBB-CSIC, 08036 Barcelona, Spain
| | - Antonino Ginel
- Department Cardiac Surgery, Hospital de la Santa Creu i Sant Pau, 08036 Barcelona, Spain
| | | | - Bo Hjorth Bentzen
- Department of Biomedical Sciences, University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - Leif Hove-Madsen
- Biomedical Research Institute Sant Pau, IIB Sant Pau, 08025 Barcelona, Spain
- Centro de Investigación Biomédica en Red Enfermedades Cardiovasculares, 28029 Madrid, Spain
- Biomedical Research Institute of Barcelona, IIBB-CSIC, 08036 Barcelona, Spain
- Correspondence: (L.H.-M.); (F.C.)
| | - Francisco Ciruela
- Pharmacology Unit, Department of Pathology and Experimental Therapeutics, School of Medicine and Health Sciences, Institute of Neurosciences, University of Barcelona, 08907 L’Hospitalet de Llobregat, Spain
- Neuropharmacology & Pain Group, Neuroscience Program, Bellvitge Institute for Biomedical Research, 08907 L’Hospitalet de Llobregat, Spain
- Correspondence: (L.H.-M.); (F.C.)
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Hao H, Dai C, Han X, Li Y. A novel therapeutic strategy for alleviating atrial remodeling by targeting exosomal miRNAs in atrial fibrillation. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2022; 1869:119365. [PMID: 36167158 DOI: 10.1016/j.bbamcr.2022.119365] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2022] [Revised: 08/29/2022] [Accepted: 09/18/2022] [Indexed: 06/16/2023]
Abstract
Atrial fibrillation (AF) is one of the most frequent cardiac arrhythmias, and atrial remodeling is related to the progression of AF. Although several therapeutic approaches have been presented in recent years, the continuously increasing mortality rate suggests that more advanced strategies for treatment are urgently needed. Exosomes regulate pathological processes through intercellular communication mediated by microribonucleic acid (miRNA) in various cardiovascular diseases (CVDs). Exosomal miRNAs associated with signaling pathways have added more complexity to an already complex direct cell-to-cell interaction. Exosome delivery of miRNAs is involved in cardiac regeneration and cardiac protection. Recent studies have found that exosomes play a critical role in the diagnosis and treatment of cardiac fibrosis. By improving exosome stability and modifying surface epitopes, specific pharmaceutical agents can be supplied to improve tropism and targeting to cells and tissues in vivo. Exosomes harboring miRNAs may have clinical utility in cell-free therapeutic approaches and may serve as prognostic and diagnostic biomarkers for AF. Currently, limitations challenge pharmaceutic design, therapeutic utility and in vivo targeted delivery to patients. The aim of this article is to review the developmental features of AF associated with exosomal miRNAs and relate them to underlying mechanisms.
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Affiliation(s)
- Hongting Hao
- Department of Cardiology, the First Affiliated Hospital, Harbin Medical University, Harbin 150001, China
| | - Chenguang Dai
- Department of Cardiology, the First Affiliated Hospital, Harbin Medical University, Harbin 150001, China
| | - Xuejie Han
- Department of Cardiology, the First Affiliated Hospital, Harbin Medical University, Harbin 150001, China
| | - Yue Li
- Department of Cardiology, the First Affiliated Hospital, Harbin Medical University, Harbin 150001, China; NHC Key Laboratory of Cell Translation, Harbin Medical University, Heilongjiang 150001, China; Key Laboratory of Hepatosplenic Surgery, Harbin Medical University, Ministry of Education, Harbin 150001, China; Key Laboratory of Cardiac Diseases and Heart Failure, Harbin Medical University, Harbin 150001, China; Heilongjiang Key Laboratory for Metabolic Disorder & Cancer Related Cardiovascular Diseases, Harbin 150081, China; Institute of Metabolic Disease, Heilongjiang Academy of Medical Science, Harbin, China.
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5
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Higher Na+-Ca2+ Exchanger Function and Triggered Activity Contribute to Male Predisposition to Atrial Fibrillation. Int J Mol Sci 2022; 23:ijms231810724. [PMID: 36142639 PMCID: PMC9501955 DOI: 10.3390/ijms231810724] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Revised: 09/06/2022] [Accepted: 09/09/2022] [Indexed: 11/17/2022] Open
Abstract
Male sex is one of the most important risk factors of atrial fibrillation (AF), with the incidence in men being almost double that in women. However, the reasons for this sex difference are unknown. Accordingly, in this study, we sought to determine whether there are sex differences in intracellular Ca2+ homeostasis in mouse atrial myocytes that might help explain male predisposition to AF. AF susceptibility was assessed in male (M) and female (F) mice (4–5 months old) using programmed electrical stimulation (EPS) protocols. Males were 50% more likely to develop AF. The Ca2+ transient amplitude was 28% higher in male atrial myocytes. Spontaneous systolic and diastolic Ca2+ releases, which are known sources of triggered activity, were significantly more frequent in males than females. The time to 90% decay of Ca2+ transient was faster in males. Males had 54% higher Na+-Ca2+ exchanger (NCX1) current density, and its expression was also more abundant. L-type Ca2+ current (ICaL) was recorded with and without BAPTA, a Ca2+ chelator. ICaL density was lower in males only in the absence of BAPTA, suggesting stronger Ca2+-dependent inactivation in males. CaV1.2 expression was similar between sexes. This study reports major sex differences in Ca2+ homeostasis in mouse atria, with larger Ca2+ transients and enhanced NCX1 function and expression in males resulting in more spontaneous Ca2+ releases. These sex differences may contribute to male susceptibility to AF by promoting triggered activity.
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6
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Djalinac N, Kolesnik E, Maechler H, Scheruebel-Posch S, Pelzmann B, Rainer PP, Foessl I, Wallner M, Scherr D, Heinemann A, Sedej S, Ljubojevic-Holzer S, von Lewinski D, Bisping E. miR-1183 Is a Key Marker of Remodeling upon Stretch and Tachycardia in Human Myocardium. Int J Mol Sci 2022; 23:ijms23136962. [PMID: 35805966 PMCID: PMC9266684 DOI: 10.3390/ijms23136962] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Revised: 06/20/2022] [Accepted: 06/21/2022] [Indexed: 11/16/2022] Open
Abstract
Many cardiac insults causing atrial remodeling are linked to either stretch or tachycardia, but a comparative characterization of their effects on early remodeling events in human myocardium is lacking. Here, we applied isometric stretch or sustained tachycardia at 2.5 Hz in human atrial trabeculae for 6 h followed by microarray gene expression profiling. Among largely independent expression patterns, we found a small common fraction with the microRNA miR-1183 as the highest up-regulated transcript (up to 4-fold). Both, acute stretch and tachycardia induced down-regulation of the predicted miR-1183 target genes ADAM20 and PLA2G7. Furthermore, miR-1183 was also significantly up-regulated in chronically remodeled atrial samples from patients with persistent atrial fibrillation (3-fold up-regulation versus sinus rhythm samples), and in ventricular myocardium from dilative cardiomyopathy hearts (2-fold up-regulation) as compared to non-failing controls. In sum, although stretch and tachycardia show distinct transcriptomic signatures in human atrial myocardium, both cardiac insults consistently regulate the expression of miR-1183 and its downstream targets in acute and chronic remodeling. Thus, elevated expression of miR-1183 might serve as a tissue biomarker for atrial remodeling and might be of potential functional significance in cardiac disease.
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Affiliation(s)
- Natasa Djalinac
- Department of Internal Medicine, Division of Cardiology, Medical University of Graz, 8036 Graz, Austria; (N.D.); (E.K.); (P.P.R.); (D.S.); (S.S.); (S.L.-H.); (E.B.)
- Unit of Human Molecular Genetics and Functional Genomics, Department of Biology, University of Padua, 35121 Padua, Italy
| | - Ewald Kolesnik
- Department of Internal Medicine, Division of Cardiology, Medical University of Graz, 8036 Graz, Austria; (N.D.); (E.K.); (P.P.R.); (D.S.); (S.S.); (S.L.-H.); (E.B.)
| | - Heinrich Maechler
- Department of Cardiothoracic Surgery, Medical University of Graz, 8036 Graz, Austria;
| | - Susanne Scheruebel-Posch
- Gottfried Schatz Research Center, Institute of Biophysics, Medical University of Graz, 8010 Graz, Austria; (S.S.-P.); (B.P.)
| | - Brigitte Pelzmann
- Gottfried Schatz Research Center, Institute of Biophysics, Medical University of Graz, 8010 Graz, Austria; (S.S.-P.); (B.P.)
| | - Peter P. Rainer
- Department of Internal Medicine, Division of Cardiology, Medical University of Graz, 8036 Graz, Austria; (N.D.); (E.K.); (P.P.R.); (D.S.); (S.S.); (S.L.-H.); (E.B.)
- BioTechMed Graz, 8036 Graz, Austria
| | - Ines Foessl
- Department of Internal Medicine, Division of Endocrinology and Diabetology, Medical University of Graz, 8010 Graz, Austria;
| | - Markus Wallner
- Department of Internal Medicine, Division of Cardiology, Medical University of Graz, 8036 Graz, Austria; (N.D.); (E.K.); (P.P.R.); (D.S.); (S.S.); (S.L.-H.); (E.B.)
- Cardiovascular Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA 19140, USA
- Correspondence: (M.W.); (D.v.L.); Tel.: +43-316-385-31261 (M.W.); +43-316-385-80684 (D.v.L.)
| | - Daniel Scherr
- Department of Internal Medicine, Division of Cardiology, Medical University of Graz, 8036 Graz, Austria; (N.D.); (E.K.); (P.P.R.); (D.S.); (S.S.); (S.L.-H.); (E.B.)
| | - Akos Heinemann
- Institute of Experimental and Clinical Pharmacology, Medical University of Graz, 8010 Graz, Austria;
| | - Simon Sedej
- Department of Internal Medicine, Division of Cardiology, Medical University of Graz, 8036 Graz, Austria; (N.D.); (E.K.); (P.P.R.); (D.S.); (S.S.); (S.L.-H.); (E.B.)
- BioTechMed Graz, 8036 Graz, Austria
- Institute of Physiology, Faculty of Medicine, University of Maribor, 2000 Maribor, Slovenia
| | - Senka Ljubojevic-Holzer
- Department of Internal Medicine, Division of Cardiology, Medical University of Graz, 8036 Graz, Austria; (N.D.); (E.K.); (P.P.R.); (D.S.); (S.S.); (S.L.-H.); (E.B.)
- BioTechMed Graz, 8036 Graz, Austria
| | - Dirk von Lewinski
- Department of Internal Medicine, Division of Cardiology, Medical University of Graz, 8036 Graz, Austria; (N.D.); (E.K.); (P.P.R.); (D.S.); (S.S.); (S.L.-H.); (E.B.)
- Correspondence: (M.W.); (D.v.L.); Tel.: +43-316-385-31261 (M.W.); +43-316-385-80684 (D.v.L.)
| | - Egbert Bisping
- Department of Internal Medicine, Division of Cardiology, Medical University of Graz, 8036 Graz, Austria; (N.D.); (E.K.); (P.P.R.); (D.S.); (S.S.); (S.L.-H.); (E.B.)
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7
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Small extracellular vesicles derived from patients with persistent atrial fibrillation exacerbate arrhythmogenesis via miR-30a-5p. Clin Sci (Lond) 2022; 136:621-637. [PMID: 35411927 DOI: 10.1042/cs20211141] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Revised: 03/21/2022] [Accepted: 04/11/2022] [Indexed: 11/17/2022]
Abstract
Small extracellular vesicles (sEVs) are nanometer-sized membranous vesicles that contribute to the pathogenesis of atrial fibrillation (AF). Here, we investigated the role of sEVs derived from patients with persistent AF in the pathophysiology of AF. First, we evaluated the pathological effects of sEVs derived from the peripheral blood of patients with persistent AF (AF-sEVs). AF-sEVs treatment reduced cell viability, caused abnormal Ca2+ handling, induced reactive oxygen species (ROS) production, and led to increased CaMKII activation of non-paced and paced atrial cardiomyocytes. Next, we analyzed the miRNA profile of AF-sEVs to investigate which components of AF-sEVs promote arrhythmias, and we selected six miRNAs that correlated with CaMKII activation. qRT-PCR experiment identified that miR-30a-5p was significantly downregulated in AF-sEVs, paced cardiomyocytes, and atrial tissues of patients with persistent AF. CaMKII was predicted by bioinformatics analysis as a miR-30a-5p target gene and validated by a dual luciferase reporter; hence, we evaluated the effects of miR-30a-5p on paced cardiomyocytes and validated miR-30a-5p as a pro-arrhythmic signature of AF-sEVs. Consequently, AF-sEVs-loaded with miR-30a-5p attenuated pacing-induced Ca2+-handling abnormalities, whereas AF-sEVs-loaded with anti-miR-30a-5p reversed the change in paced cardiomyocytes. Taken together, the regulation of CaMKII by miR-30a-5p revealed that miR-30a-5p is a major mediator for AF-sEVs-mediated AF pathogenesis. Accordingly, these findings suggest that sEVs derived from patients with persistent AF exacerbate arrhythmogenesis via miR-30a-5p.
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8
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Petkova MA, Dobrzynski H. Do human sinoatrial node cells have t-tubules? TRANSLATIONAL RESEARCH IN ANATOMY 2021. [DOI: 10.1016/j.tria.2021.100131] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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9
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Kaplan AD, Joca HC, Boyman L, Greiser M. Calcium Signaling Silencing in Atrial Fibrillation: Implications for Atrial Sodium Homeostasis. Int J Mol Sci 2021; 22:10513. [PMID: 34638854 PMCID: PMC8508839 DOI: 10.3390/ijms221910513] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Revised: 09/14/2021] [Accepted: 09/14/2021] [Indexed: 12/19/2022] Open
Abstract
Atrial fibrillation (AF) is the most common type of cardiac arrhythmia, affecting more than 33 million people worldwide. Despite important advances in therapy, AF's incidence remains high, and treatment often results in recurrence of the arrhythmia. A better understanding of the cellular and molecular changes that (1) trigger AF and (2) occur after the onset of AF will help to identify novel therapeutic targets. Over the past 20 years, a large body of research has shown that intracellular Ca2+ handling is dramatically altered in AF. While some of these changes are arrhythmogenic, other changes counteract cellular arrhythmogenic mechanisms (Calcium Signaling Silencing). The intracellular Na+ concentration ([Na+])i is a key regulator of intracellular Ca2+ handling in cardiac myocytes. Despite its importance in the regulation of intracellular Ca2+ handling, little is known about [Na+]i, its regulation, and how it might be changed in AF. Previous work suggests that there might be increases in the late component of the atrial Na+ current (INa,L) in AF, suggesting that [Na+]i levels might be high in AF. Indeed, a pharmacological blockade of INa,L has been suggested as a treatment for AF. Here, we review calcium signaling silencing and changes in intracellular Na+ homeostasis during AF. We summarize the proposed arrhythmogenic mechanisms associated with increases in INa,L during AF and discuss the evidence from clinical trials that have tested the pharmacological INa,L blocker ranolazine in the treatment of AF.
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Affiliation(s)
- Aaron D. Kaplan
- Center for Biomedical Engineering and Technology, Department of Physiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA; (A.D.K.); (H.C.J.); (L.B.)
- Division of Cardiovascular Medicine, Department of Medicine, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Humberto C. Joca
- Center for Biomedical Engineering and Technology, Department of Physiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA; (A.D.K.); (H.C.J.); (L.B.)
| | - Liron Boyman
- Center for Biomedical Engineering and Technology, Department of Physiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA; (A.D.K.); (H.C.J.); (L.B.)
| | - Maura Greiser
- Center for Biomedical Engineering and Technology, Department of Physiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA; (A.D.K.); (H.C.J.); (L.B.)
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10
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Jost N, Christ T, Magyar J. New Strategies for the Treatment of Atrial Fibrillation. Pharmaceuticals (Basel) 2021; 14:ph14090926. [PMID: 34577626 PMCID: PMC8466466 DOI: 10.3390/ph14090926] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Revised: 09/07/2021] [Accepted: 09/08/2021] [Indexed: 12/19/2022] Open
Abstract
Atrial fibrillation (AF) is the most prevalent cardiac arrhythmia in the clinical practice. It significantly contributes to the morbidity and mortality of the elderly population. Over the past 25-30 years intense effort in basic research has advanced the understanding of the relationship between the pathophysiology of AF and atrial remodelling. Nowadays it is clear that the various forms of atrial remodelling (electrical, contractile and structural) play crucial role in initiating and maintaining the persistent and permanent types of AF. Unlike in ventricular fibrillation, in AF rapid ectopic firing originating from pulmonary veins and re-entry mechanism may induce and maintain (due to atrial remodelling) this complex cardiac arrhythmia. The present review presents and discusses in detail the latest knowledge on the role of remodelling in AF. Special attention is paid to novel concepts and pharmacological targets presumably relevant to the drug treatment of atrial fibrillation.
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Affiliation(s)
- Norbert Jost
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, 6725 Szeged, Hungary
- Department of Pharmacology and Pharmacotherapy, Interdisciplinary Excellence Centre, University of Szeged, 6725 Szeged, Hungary
- ELKH-SZTE Research Group for Cardiovascular Pharmacology, Eötvös Loránd Research Network, 6725 Szeged, Hungary
- Correspondence:
| | - Torsten Christ
- Institute of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany;
- DZHK (German Center for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, 20246 Hamburg, Germany
| | - János Magyar
- Department of Physiology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary;
- Department of Sport Physiology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary
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11
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Inhibition of Ca 2+-dependent protein kinase C rescues high calcium-induced pro-arrhythmogenic cardiac alternans in rabbit hearts. Pflugers Arch 2021; 473:1315-1327. [PMID: 34145500 DOI: 10.1007/s00424-021-02574-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Revised: 04/22/2021] [Accepted: 05/03/2021] [Indexed: 10/21/2022]
Abstract
Cardiac alternans closely linked to calcium dysregulation is a crucial risk factor for fatal arrhythmia causing especially sudden death. Calcium overload is well-known to activate Ca2+-dependent protein kinase C (PKC); however, the effects of PKC on arrhythmogenic cardiac alternans have not yet been investigated. This study aimed to determine the contributions of PKC activities in cardiac alternans associated with calcium cycling disturbances. In the present study, action potential duration alternans (APD-ALT) induced by high free intracellular calcium ([Ca2+]i) exerted not only in a calcium concentration-dependent manner but also in a frequency-dependent manner. High [Ca2+]i-induced APD-ALT was suppressed by not only BAPTA-AM but also nifedipine. On the other hand, PKC inhibitors BIM and Gö 6976 eliminated high [Ca2+]i-induced APD-ALT, and PKC activator PMA was found to induce APD-ALT at normal [Ca2+]i condition. Furthermore, BIM effectively prevented calcium transient alternans (CaT-ALT) and even CaT disorders caused by calcium overload. Moreover, BIM not only eliminated electrocardiographic T-wave alternans (TWA) caused by calcium dysregulation, but also lowered the incidence of ventricular arrhythmias in isolated hearts. What's more, BIM prevented the expression of PKC α upregulated by calcium overload in high calcium-perfused hearts. We firstly found that pharmacologically inhibiting Ca2+-dependent PKC over-activation suppressed high [Ca2+]i-induced cardiac alternans. This recognition indicates that inhibition of PKC activities may become a therapeutic target for the prevention of pro-arrhythmogenic cardiac alternans associated with calcium dysregulation.
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12
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Vagos MR, Arevalo H, Heijman J, Schotten U, Sundnes J. A Computational Study of the Effects of Tachycardia-Induced Remodeling on Calcium Wave Propagation in Rabbit Atrial Myocytes. Front Physiol 2021; 12:651428. [PMID: 33897459 PMCID: PMC8063103 DOI: 10.3389/fphys.2021.651428] [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: 01/09/2021] [Accepted: 03/08/2021] [Indexed: 11/24/2022] Open
Abstract
In atrial cardiomyocytes without a well-developed T-tubule system, calcium diffuses from the periphery toward the center creating a centripetal wave pattern. During atrial fibrillation, rapid activation of atrial myocytes induces complex remodeling in diffusion properties that result in failure of calcium to propagate in a fully regenerative manner toward the center; a phenomenon termed “calcium silencing.” This has been observed in rabbit atrial myocytes after exposure to prolonged rapid pacing. Although experimental studies have pointed to possible mechanisms underlying calcium silencing, their individual effects and relative importance remain largely unknown. In this study we used computational modeling of the rabbit atrial cardiomyocyte to query the individual and combined effects of the proposed mechanisms leading to calcium silencing and abnormal calcium wave propagation. We employed a population of models obtained from a newly developed model of the rabbit atrial myocyte with spatial representation of intracellular calcium handling. We selected parameters in the model that represent experimentally observed cellular remodeling which have been implicated in calcium silencing, and scaled their values in the population to match experimental observations. In particular, we changed the maximum conductances of ICaL, INCX, and INaK, RyR open probability, RyR density, Serca2a density, and calcium buffering strength. We incorporated remodeling in a population of 16 models by independently varying parameters that reproduce experimentally observed cellular remodeling, and quantified the resulting alterations in calcium dynamics and wave propagation patterns. The results show a strong effect of ICaL in driving calcium silencing, with INCX, INaK, and RyR density also resulting in calcium silencing in some models. Calcium alternans was observed in some models where INCX and Serca2a density had been changed. Simultaneously incorporating changes in all remodeled parameters resulted in calcium silencing in all models, indicating the predominant role of decreasing ICaL in the population phenotype.
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Affiliation(s)
- Márcia R Vagos
- Simula Research Laboratory, Computational Physiology Department, Lysaker, Norway
| | - Hermenegild Arevalo
- Simula Research Laboratory, Computational Physiology Department, Lysaker, Norway
| | - Jordi Heijman
- Faculty of Health, Medicine and Life Sciences, School for Cardiovascular Diseases, Maastricht, Netherlands
| | - Ulrich Schotten
- Faculty of Health, Medicine and Life Sciences, School for Cardiovascular Diseases, Maastricht, Netherlands
| | - Joakim Sundnes
- Simula Research Laboratory, Computational Physiology Department, Lysaker, Norway.,Department of Informatics, University of Oslo, Oslo, Norway
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13
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Zhang Y, Qi Y, Li JJ, He WJ, Gao XH, Zhang Y, Sun X, Tong J, Zhang J, Deng XL, Du XJ, Xie W. Stretch-induced sarcoplasmic reticulum calcium leak is causatively associated with atrial fibrillation in pressure-overloaded hearts. Cardiovasc Res 2021; 117:1091-1102. [PMID: 32531044 DOI: 10.1093/cvr/cvaa163] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Revised: 01/06/2020] [Accepted: 06/05/2020] [Indexed: 12/21/2022] Open
Abstract
AIMS Despite numerous reports documenting an important role of hypertension in the development of atrial fibrillation (AF), the detailed mechanism underlying the pathological process remains incompletely understood. Here, we aim to test the hypothesis that diastolic sarcoplasmic reticulum (SR) Ca2+ leak in atrial myocytes, induced by mechanical stretch due to elevated pressure in the left atrium (LA), plays an essential role in the AF development in pressure-overloaded hearts. METHODS AND RESULTS Isolated mouse atrial myocytes subjected to acute axial stretch displayed an immediate elevation of SR Ca2+ leak. Using a mouse model of transverse aortic constriction (TAC), the relation between stretch, SR Ca2+ leak, and AF susceptibility was further tested. At 36 h post-TAC, SR Ca2+ leak in cardiomyocytes from the LA (with haemodynamic stress), but not right atrium (without haemodynamic stress), significantly increased, which was further elevated at 4 weeks post-TAC. Accordingly, AF susceptibility to atrial burst pacing in the 4-week TAC mice were also significantly increased, which was unaffected by inhibition of atrial fibrosis or inflammation via deletion of galectin-3. Western blotting revealed that type 2 ryanodine receptor (RyR2) in left atrial myocytes of TAC mice was oxidized due to activation and up-regulation of Nox2 and Nox4. Direct rescue of dysfunctional RyR2 with dantrolene or rycal S107 reduced diastolic SR Ca2+ leak in left atrial myocytes and prevented atrial burst pacing stimulated AF. CONCLUSION Our study demonstrated for the first time the increased SR Ca2+ leak mediated by enhanced oxidative stress in left atrial myocytes that is causatively associated with higher AF susceptibility in pressure-overloaded hearts.
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Affiliation(s)
- Yi Zhang
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, Shaanxi, China
| | - Ying Qi
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, No. 28 West Xianning Road, Xi'an, Shaanxi 710049, China
| | - Jing-Jing Li
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, No. 28 West Xianning Road, Xi'an, Shaanxi 710049, China
| | - Wen-Jin He
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, No. 28 West Xianning Road, Xi'an, Shaanxi 710049, China
| | - Xiao-Hang Gao
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, No. 28 West Xianning Road, Xi'an, Shaanxi 710049, China
| | - Yu Zhang
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, Shaanxi, China
| | - Xia Sun
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, Shaanxi, China
| | - Jie Tong
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, No. 28 West Xianning Road, Xi'an, Shaanxi 710049, China
| | - Jianbao Zhang
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, No. 28 West Xianning Road, Xi'an, Shaanxi 710049, China
| | - Xiu-Ling Deng
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, Shaanxi, China
- Cardiovascular Research Centre, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, Shaanxi, China
| | - Xiao-Jun Du
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, Shaanxi, China
| | - Wenjun Xie
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, No. 28 West Xianning Road, Xi'an, Shaanxi 710049, China
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14
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Qi XY, Vahdati Hassani F, Hoffmann D, Xiao J, Xiong F, Villeneuve LR, Ljubojevic-Holzer S, Kamler M, Abu-Taha I, Heijman J, Bers DM, Dobrev D, Nattel S. Inositol Trisphosphate Receptors and Nuclear Calcium in Atrial Fibrillation. Circ Res 2020; 128:619-635. [PMID: 33375812 DOI: 10.1161/circresaha.120.317768] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
RATIONALE The mechanisms underlying atrial fibrillation (AF), the most common clinical arrhythmia, are poorly understood. Nucleoplasmic Ca2+ regulates gene expression, but the nature and significance of nuclear Ca2+-changes in AF are largely unknown. OBJECTIVE To elucidate mechanisms by which AF alters atrial-cardiomyocyte nuclear Ca2+ ([Ca2+]Nuc) and CaMKII (Ca2+/calmodulin-dependent protein kinase-II)-related signaling. METHODS AND RESULTS Atrial cardiomyocytes were isolated from control and AF dogs (kept in AF by atrial tachypacing [600 bpm × 1 week]). [Ca2+]Nuc and cytosolic [Ca2+] ([Ca2+]Cyto) were recorded via confocal microscopy. Diastolic [Ca2+]Nuc was greater than [Ca2+]Cyto under control conditions, while resting [Ca2+]Nuc was similar to [Ca2+]Cyto; both diastolic and resting [Ca2+]Nuc increased with AF. IP3R (Inositol-trisphosphate receptor) stimulation produced larger [Ca2+]Nuc increases in AF versus control cardiomyocytes, and IP3R-blockade suppressed the AF-related [Ca2+]Nuc differences. AF upregulated nuclear protein expression of IP3R1 (IP3R-type 1) and of phosphorylated CaMKII (immunohistochemistry and immunoblot) while decreasing the nuclear/cytosolic expression ratio for HDAC4 (histone deacetylase type-4). Isolated atrial cardiomyocytes tachypaced at 3 Hz for 24 hours mimicked AF-type [Ca2+]Nuc changes and L-type calcium current decreases versus 1-Hz-paced cardiomyocytes; these changes were prevented by IP3R knockdown with short-interfering RNA directed against IP3R1. Nuclear/cytosolic HDAC4 expression ratio was decreased by 3-Hz pacing, while nuclear CaMKII phosphorylation was increased. Either CaMKII-inhibition (by autocamtide-2-related peptide) or IP3R-knockdown prevented the CaMKII-hyperphosphorylation and nuclear-to-cytosolic HDAC4 shift caused by 3-Hz pacing. In human atrial cardiomyocytes from AF patients, nuclear IP3R1-expression was significantly increased, with decreased nuclear/nonnuclear HDAC4 ratio. MicroRNA-26a was predicted to target ITPR1 (confirmed by luciferase assay) and was downregulated in AF atrial cardiomyocytes; microRNA-26a silencing reproduced AF-induced IP3R1 upregulation and nuclear diastolic Ca2+-loading. CONCLUSIONS AF increases atrial-cardiomyocyte nucleoplasmic [Ca2+] by IP3R1-upregulation involving miR-26a, leading to enhanced IP3R1-CaMKII-HDAC4 signaling and L-type calcium current downregulation. Graphic Abstract: A graphic abstract is available for this article.
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Affiliation(s)
- Xiao-Yan Qi
- Medicine, Montreal Heart Institute, Université de Montréal, Canada (X.-Y.Q., F.V.H., J.X., F.X., L.R.V., D.D., S.N.)
| | - Faezeh Vahdati Hassani
- Medicine, Montreal Heart Institute, Université de Montréal, Canada (X.-Y.Q., F.V.H., J.X., F.X., L.R.V., D.D., S.N.)
| | - Dennis Hoffmann
- Institute of Pharmacology, West German Heart and Vascular Center, Medical Faculty, University Duisburg-Essen, Germany (D.H., I.A.-T., J.H., D.D., S.N.)
| | - Jiening Xiao
- Medicine, Montreal Heart Institute, Université de Montréal, Canada (X.-Y.Q., F.V.H., J.X., F.X., L.R.V., D.D., S.N.)
| | - Feng Xiong
- Medicine, Montreal Heart Institute, Université de Montréal, Canada (X.-Y.Q., F.V.H., J.X., F.X., L.R.V., D.D., S.N.)
| | - Louis R Villeneuve
- Medicine, Montreal Heart Institute, Université de Montréal, Canada (X.-Y.Q., F.V.H., J.X., F.X., L.R.V., D.D., S.N.)
| | | | - Markus Kamler
- Departments of Thoracic and Cardiovascular Surgery Huttrop (M.K.)
| | - Issam Abu-Taha
- Institute of Pharmacology, West German Heart and Vascular Center, Medical Faculty, University Duisburg-Essen, Germany (D.H., I.A.-T., J.H., D.D., S.N.)
| | - Jordi Heijman
- Institute of Pharmacology, West German Heart and Vascular Center, Medical Faculty, University Duisburg-Essen, Germany (D.H., I.A.-T., J.H., D.D., S.N.).,Cardiology, Cardiovascular Research Institute Maastricht, Faculty of Health, Medicine, and Life Sciences, Maastricht University, the Netherlands (J.H.)
| | - Donald M Bers
- Physiology, University of California, Davis (S.L.-H., D.M.B.)
| | - Dobromir Dobrev
- Medicine, Montreal Heart Institute, Université de Montréal, Canada (X.-Y.Q., F.V.H., J.X., F.X., L.R.V., D.D., S.N.).,Institute of Pharmacology, West German Heart and Vascular Center, Medical Faculty, University Duisburg-Essen, Germany (D.H., I.A.-T., J.H., D.D., S.N.)
| | - Stanley Nattel
- Medicine, Montreal Heart Institute, Université de Montréal, Canada (X.-Y.Q., F.V.H., J.X., F.X., L.R.V., D.D., S.N.).,Institute of Pharmacology, West German Heart and Vascular Center, Medical Faculty, University Duisburg-Essen, Germany (D.H., I.A.-T., J.H., D.D., S.N.).,Pharmacology, McGill University Montreal, Canada (S.N.).,IHU LIRYC, Bordeaux, France (S.N.)
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15
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Christoph J, Lebert J. Inverse mechano-electrical reconstruction of cardiac excitation wave patterns from mechanical deformation using deep learning. CHAOS (WOODBURY, N.Y.) 2020; 30:123134. [PMID: 33380038 DOI: 10.1063/5.0023751] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Accepted: 11/18/2020] [Indexed: 06/12/2023]
Abstract
The inverse mechano-electrical problem in cardiac electrophysiology is the attempt to reconstruct electrical excitation or action potential wave patterns from the heart's mechanical deformation that occurs in response to electrical excitation. Because heart muscle cells contract upon electrical excitation due to the excitation-contraction coupling mechanism, the resulting deformation of the heart should reflect macroscopic action potential wave phenomena. However, whether the relationship between macroscopic electrical and mechanical phenomena is well-defined and unique enough to be utilized for an inverse imaging technique in which mechanical activation mapping is used as a surrogate for electrical mapping has yet to be determined. Here, we provide a numerical proof-of-principle that deep learning can be used to solve the inverse mechano-electrical problem in phenomenological two- and three-dimensional computer simulations of the contracting heart wall, or in elastic excitable media, with muscle fiber anisotropy. We trained a convolutional autoencoder neural network to learn the complex relationship between electrical excitation, active stress, and tissue deformation during both focal or reentrant chaotic wave activity and, consequently, used the network to successfully estimate or reconstruct electrical excitation wave patterns from mechanical deformation in sheets and bulk-shaped tissues, even in the presence of noise and at low spatial resolutions. We demonstrate that even complicated three-dimensional electrical excitation wave phenomena, such as scroll waves and their vortex filaments, can be computed with very high reconstruction accuracies of about 95% from mechanical deformation using autoencoder neural networks, and we provide a comparison with results that were obtained previously with a physics- or knowledge-based approach.
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Affiliation(s)
- Jan Christoph
- Department of Cardiology and Pneumology, University Medical Center Göttingen, 37075 Göttingen, Germany
| | - Jan Lebert
- Department of Cardiology and Pneumology, University Medical Center Göttingen, 37075 Göttingen, Germany
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16
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Parahuleva MS, Kockskämper J, Heger J, Grimm W, Scherer A, Bühler S, Kreutz J, Schulz R, Euler G. Structural, Pro-Inflammatory and Calcium Handling Remodeling Underlies Spontaneous Onset of Paroxysmal Atrial Fibrillation in JDP2-Overexpressing Mice. Int J Mol Sci 2020; 21:E9095. [PMID: 33265909 PMCID: PMC7731172 DOI: 10.3390/ijms21239095] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2020] [Revised: 11/26/2020] [Accepted: 11/27/2020] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND Cardiac-specific JDP2 overexpression provokes ventricular dysfunction and atrial dilatation in mice. We performed in vivo studies on JDP2-overexpressing mice to investigate the impact of JDP2 on the predisposition to spontaneous atrial fibrillation (AF). METHODS JDP2-overexpression was started by withdrawal of a doxycycline diet in 4-week-old mice. The spontaneous onset of AF was documented by ECG within 4 to 5 weeks of JDP2 overexpression. Gene expression was analyzed by real-time RT-PCR and Western blots. RESULTS In atrial tissue of JDP2 mice, besides the 3.6-fold increase of JDP2 mRNA, no changes could be detected within one week of JDP2 overexpression. Atrial dilatation and hypertrophy, combined with elongated cardiomyocytes and fibrosis, became evident after 5 weeks of JDP2 overexpression. Electrocardiogram (ECG) recordings revealed prolonged PQ-intervals and broadened P-waves and QRS-complexes, as well as AV-blocks and paroxysmal AF. Furthermore, reductions were found in the atrial mRNA and protein level of the calcium-handling proteins NCX, Cav1.2 and RyR2, as well as of connexin40 mRNA. mRNA of the hypertrophic marker gene ANP, pro-inflammatory MCP1, as well as markers of immune cell infiltration (CD68, CD20) were increased in JDP2 mice. CONCLUSION JDP2 is an important regulator of atrial calcium and immune homeostasis and is involved in the development of atrial conduction defects and arrhythmogenic substrates preceding paroxysmal AF.
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Affiliation(s)
- Mariana S. Parahuleva
- Internal Medicine/Cardiology and Angiology, University Hospital of Giessen and Marburg, 35033 Marburg, Germany; (W.G.); (J.K.)
| | - Jens Kockskämper
- Biochemical-Pharmacological Centre (BPC) Marburg, Institute of Pharmacology and Clinical Pharmacy, University of Marburg, 35043 Marburg, Germany; (J.K.); (A.S.); (S.B.)
| | - Jacqueline Heger
- Institute of Physiology, Justus Liebig University, 35392 Giessen, Germany; (J.H.); (R.S.); (G.E.)
| | - Wolfram Grimm
- Internal Medicine/Cardiology and Angiology, University Hospital of Giessen and Marburg, 35033 Marburg, Germany; (W.G.); (J.K.)
| | - Anna Scherer
- Biochemical-Pharmacological Centre (BPC) Marburg, Institute of Pharmacology and Clinical Pharmacy, University of Marburg, 35043 Marburg, Germany; (J.K.); (A.S.); (S.B.)
| | - Sarah Bühler
- Biochemical-Pharmacological Centre (BPC) Marburg, Institute of Pharmacology and Clinical Pharmacy, University of Marburg, 35043 Marburg, Germany; (J.K.); (A.S.); (S.B.)
| | - Julian Kreutz
- Internal Medicine/Cardiology and Angiology, University Hospital of Giessen and Marburg, 35033 Marburg, Germany; (W.G.); (J.K.)
| | - Rainer Schulz
- Institute of Physiology, Justus Liebig University, 35392 Giessen, Germany; (J.H.); (R.S.); (G.E.)
| | - Gerhild Euler
- Institute of Physiology, Justus Liebig University, 35392 Giessen, Germany; (J.H.); (R.S.); (G.E.)
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17
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Geng M, Lin A, Nguyen TP. Revisiting Antiarrhythmic Drug Therapy for Atrial Fibrillation: Reviewing Lessons Learned and Redefining Therapeutic Paradigms. Front Pharmacol 2020; 11:581837. [PMID: 33240090 PMCID: PMC7680856 DOI: 10.3389/fphar.2020.581837] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Accepted: 09/17/2020] [Indexed: 12/12/2022] Open
Abstract
Since the clinical use of digitalis as the first pharmacological therapy for atrial fibrillation (AF) 235 years ago in 1785, antiarrhythmic drug therapy has advanced considerably and become a cornerstone of AF clinical management. Yet, a preventive or curative panacea for sustained AF does not exist despite the rise of AF global prevalence to epidemiological proportions. While multiple elevated risk factors for AF have been established, the natural history and etiology of AF remain incompletely understood. In the present article, the first section selectively highlights some disappointing shortcomings and current efforts in antiarrhythmic drug therapy to uncover reasons why AF is such a clinical challenge. The second section discusses some modern takes on the natural history of AF as a relentless, progressive fibro-inflammatory "atriomyopathy." The final section emphasizes the need to redefine therapeutic strategies on par with new insights of AF pathophysiology.
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Affiliation(s)
| | | | - Thao P. Nguyen
- Division of Cardiology, Department of Medicine, The Cardiovascular Research Laboratory, David Geffen School of Medicine at UCLA, Los Angeles, CA, United States
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18
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Marchena M, Echebarria B. Influence of the tubular network on the characteristics of calcium transients in cardiac myocytes. PLoS One 2020; 15:e0231056. [PMID: 32302318 PMCID: PMC7164608 DOI: 10.1371/journal.pone.0231056] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Accepted: 03/14/2020] [Indexed: 01/09/2023] Open
Abstract
Transverse and axial tubules (TATS) are an essential ingredient of the excitation-contraction machinery that allow the effective coupling of L-type Calcium Channels (LCC) and ryanodine receptors (RyR2). They form a regular network in ventricular cells, while their presence in atrial myocytes is variable regionally and among animal species We have studied the effect of variations in the TAT network using a bidomain computational model of an atrial myocyte with variable density of tubules. At each z-line the t-tubule length is obtained from an exponential distribution, with a given mean penetration length. This gives rise to a distribution of t-tubules in the cell that is characterized by the fractional area (F.A.) occupied by the t-tubules. To obtain consistent results, we average over different realizations of the same mean penetration length. To this, in some simulations we add the effect of a network of axial tubules. Then we study global properties of calcium signaling, as well as regional heterogeneities and local properties of sparks and RyR2 openings. In agreement with recent experiments in detubulated ventricular and atrial cells, we find that detubulation reduces the calcium transient and synchronization in release. However, it does not affect sarcoplasmic reticulum (SR) load, so the decrease in SR calcium release is due to regional differences in Ca2+ release, that is restricted to the cell periphery in detubulated cells. Despite the decrease in release, the release gain is larger in detubulated cells, due to recruitment of orphaned RyR2s, i.e, those that are not confronting a cluster of LCCs. This probably provides a safeguard mechanism, allowing physiological values to be maintained upon small changes in the t-tubule density. Finally, we do not find any relevant change in spark properties between tubulated and detubulated cells, suggesting that the differences found in experiments could be due to differential properties of the RyR2s in the membrane and in the t-tubules, not incorporated in the present model. This work will help understand the effect of detubulation, that has been shown to occur in disease conditions such as heart failure (HF) in ventricular cells, or atrial fibrillation (AF) in atrial cells.
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Affiliation(s)
- Miquel Marchena
- Departament de Física, Universitat Politècnica de Catalunya, Barcelona, Spain
| | - Blas Echebarria
- Departament de Física, Universitat Politècnica de Catalunya, Barcelona, Spain
- * E-mail:
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19
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Mitochondrial Dysfunction Underlies Cardiomyocyte Remodeling in Experimental and Clinical Atrial Fibrillation. Cells 2019; 8:cells8101202. [PMID: 31590355 PMCID: PMC6829298 DOI: 10.3390/cells8101202] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Revised: 10/01/2019] [Accepted: 10/03/2019] [Indexed: 12/21/2022] Open
Abstract
Atrial fibrillation (AF), the most common progressive tachyarrhythmia, results in structural remodeling which impairs electrical activation of the atria, rendering them increasingly permissive to the arrhythmia. Previously, we reported on endoplasmic reticulum stress and NAD+ depletion in AF, suggesting a role for mitochondrial dysfunction in AF progression. Here, we examined mitochondrial function in experimental model systems for AF (tachypaced HL-1 atrial cardiomyocytes and Drosophila melanogaster) and validated findings in clinical AF. Tachypacing of HL-1 cardiomyocytes progressively induces mitochondrial dysfunction, evidenced by impairment of mitochondrial Ca2+-handling, upregulation of mitochondrial stress chaperones and a decrease in the mitochondrial membrane potential, respiration and ATP production. Atrial biopsies from AF patients display mitochondrial dysfunction, evidenced by aberrant ATP levels, upregulation of a mitochondrial stress chaperone and fragmentation of the mitochondrial network. The pathophysiological role of mitochondrial dysfunction is substantiated by the attenuation of AF remodeling by preventing an increased mitochondrial Ca2+-influx through partial blocking or downregulation of the mitochondrial calcium uniporter, and by SS31, a compound that improves bioenergetics in mitochondria. Together, these results show that conservation of the mitochondrial function protects against tachypacing-induced cardiomyocyte remodeling and identify this organelle as a potential novel therapeutic target.
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20
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Dai W, Laforest B, Tyan L, Shen KM, Nadadur RD, Alvarado FJ, Mazurek SR, Lazarevic S, Gadek M, Wang Y, Li Y, Valdivia HH, Shen L, Broman MT, Moskowitz IP, Weber CR. A calcium transport mechanism for atrial fibrillation in Tbx5-mutant mice. eLife 2019; 8:41814. [PMID: 30896405 PMCID: PMC6428569 DOI: 10.7554/elife.41814] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Accepted: 02/28/2019] [Indexed: 02/06/2023] Open
Abstract
Risk for Atrial Fibrillation (AF), the most common human arrhythmia, has a major genetic component. The T-box transcription factor TBX5 influences human AF risk, and adult-specific Tbx5-mutant mice demonstrate spontaneous AF. We report that TBX5 is critical for cellular Ca2+ homeostasis, providing a molecular mechanism underlying the genetic implication of TBX5 in AF. We show that cardiomyocyte action potential (AP) abnormalities in Tbx5-deficient atrial cardiomyocytes are caused by a decreased sarcoplasmic reticulum (SR) Ca2+ ATPase (SERCA2)-mediated SR calcium uptake which was balanced by enhanced trans-sarcolemmal calcium fluxes (calcium current and sodium/calcium exchanger), providing mechanisms for triggered activity. The AP defects, cardiomyocyte ectopy, and AF caused by TBX5 deficiency were rescued by phospholamban removal, which normalized SERCA function. These results directly link transcriptional control of SERCA2 activity, depressed SR Ca2+ sequestration, enhanced trans-sarcolemmal calcium fluxes, and AF, establishing a mechanism underlying the genetic basis for a Ca2+-dependent pathway for AF risk. The human heart contains four distinct chambers that work together to pump blood around the body. In individuals with a condition called atrial fibrillation, two of the chambers (known as the atria) beat irregularly and are unable to push all the blood they hold into the other two chambers of the heart. This can cause heart failure and increases the likelihood of blood clots, which may lead to stroke and heart attacks. Small molecules called calcium ions play a crucial role in regulating how and when the atria contract by driving electrical activity in heart cells. To contract the atria, a storage compartment within heart cells known as the sarcoplasmic reticulum releases calcium ions into the main compartment of the cells. Calcium ions also enter the cell from the surrounding tissue. As the atria relax, calcium ions are pumped back into the sarcoplasmic reticulum or out of the cell by specific transport proteins. Individuals with mutations in a gene called Tbx5 are more likely to develop atrial fibrillation than other people, but it was not clear how such gene mutations contribute to the disease. Here, Dai, Laforest et al. used mice with a mutation in the Tbx5 gene to study how defects in Tbx5 affect electrical activity in heart cells. The experiments found that the Tbx5 gene was critical for calcium ions to drive normal electrical activity in mouse heart cells. Compared with heart cells from normal mice, the heart cells from the mutant mice had decreased flow of calcium ions into the sarcoplasmic reticulum and increased flow of calcium ions out of the cell. These findings provide a direct link between atrial fibrillation and the flow of calcium ions in heart cells. Together with previous work, these findings indicate that multiple different mechanisms could lead to atrial fibrillation, but that many of these involve changes in the flow of calcium ions. Therefore, personalized medicine, where clinicians uncover the specific mechanisms responsible for atrial fibrillation in individual patients, may play an important role in treating this condition in the future.
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Affiliation(s)
- Wenli Dai
- Department of Pathology, University of Chicago, Chicago, United States
| | - Brigitte Laforest
- Departments of Pediatrics, Pathology, and Human Genetics, University of Chicago, Chicago, United States
| | - Leonid Tyan
- Department of Pathology, University of Chicago, Chicago, United States
| | - Kaitlyn M Shen
- Departments of Pediatrics, Pathology, and Human Genetics, University of Chicago, Chicago, United States
| | - Rangarajan D Nadadur
- Departments of Pediatrics, Pathology, and Human Genetics, University of Chicago, Chicago, United States
| | - Francisco J Alvarado
- Department of Medicine, Division of Cardiovascular Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, United States
| | - Stefan R Mazurek
- Department of Medicine, University of Chicago, Chicago, United States
| | - Sonja Lazarevic
- Departments of Pediatrics, Pathology, and Human Genetics, University of Chicago, Chicago, United States
| | - Margaret Gadek
- Departments of Pediatrics, Pathology, and Human Genetics, University of Chicago, Chicago, United States
| | - Yitang Wang
- Department of Pathology, University of Chicago, Chicago, United States
| | - Ye Li
- Department of Pathology, University of Chicago, Chicago, United States
| | - Hector H Valdivia
- Department of Medicine, Division of Cardiovascular Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, United States
| | - Le Shen
- Department of Pathology, University of Chicago, Chicago, United States.,Section of Neurosurgery, Department of Surgery, University of Chicago, Chicago, United States
| | - Michael T Broman
- Department of Medicine, University of Chicago, Chicago, United States
| | - Ivan P Moskowitz
- Departments of Pediatrics, Pathology, and Human Genetics, University of Chicago, Chicago, United States
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21
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Thomas D, Christ T, Fabritz L, Goette A, Hammwöhner M, Heijman J, Kockskämper J, Linz D, Odening KE, Schweizer PA, Wakili R, Voigt N. German Cardiac Society Working Group on Cellular Electrophysiology state-of-the-art paper: impact of molecular mechanisms on clinical arrhythmia management. Clin Res Cardiol 2018; 108:577-599. [PMID: 30306295 DOI: 10.1007/s00392-018-1377-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Accepted: 09/24/2018] [Indexed: 12/19/2022]
Abstract
Cardiac arrhythmias remain a common challenge and are associated with significant morbidity and mortality. Effective and safe rhythm control strategies are a primary, yet unmet need in everyday clinical practice. Despite significant pharmacological and technological advances, including catheter ablation and device-based therapies, the development of more effective alternatives is of significant interest to increase quality of life and to reduce symptom burden, hospitalizations and mortality. The mechanistic understanding of pathophysiological pathways underlying cardiac arrhythmias has advanced profoundly, opening up novel avenues for mechanism-based therapeutic approaches. Current management of arrhythmias, however, is primarily guided by clinical and demographic characteristics of patient groups as opposed to individual, patient-specific mechanisms and pheno-/genotyping. With this state-of-the-art paper, the Working Group on Cellular Electrophysiology of the German Cardiac Society aims to close the gap between advanced molecular understanding and clinical decision-making in cardiac electrophysiology. The significance of cellular electrophysiological findings for clinical arrhythmia management constitutes the main focus of this document. Clinically relevant knowledge of pathophysiological pathways of arrhythmias and cellular mechanisms of antiarrhythmic interventions are summarized. Furthermore, the specific molecular background for the initiation and perpetuation of atrial and ventricular arrhythmias and mechanism-based strategies for therapeutic interventions are highlighted. Current "hot topics" in atrial fibrillation are critically appraised. Finally, the establishment and support of cellular and translational electrophysiology programs in clinical rhythmology departments is called for to improve basic-science-guided patient management.
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Affiliation(s)
- Dierk Thomas
- Department of Cardiology, Medical University Hospital, Im Neuenheimer Feld 410, 69120, Heidelberg, Germany. .,HCR (Heidelberg Center for Heart Rhythm Disorders), Heidelberg, Germany. .,DZHK (German Center for Cardiovascular Research), partner site Heidelberg/Mannheim, Heidelberg, Germany.
| | - Torsten Christ
- Department of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.,DZHK (German Center for Cardiovascular Research), partner site Hamburg/Kiel/Lübeck, Hamburg, Germany
| | - Larissa Fabritz
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, UK.,Department of Cardiology, UHB NHS Trust, Birmingham, UK.,Department of Cardiovascular Medicine, Division of Rhythmology, University Hospital Münster, Münster, Germany
| | - Andreas Goette
- St. Vincenz-Hospital, Paderborn, Germany.,Working Group: Molecular Electrophysiology, University Hospital Magdeburg, Magdeburg, Germany
| | - Matthias Hammwöhner
- St. Vincenz-Hospital, Paderborn, Germany.,Working Group: Molecular Electrophysiology, University Hospital Magdeburg, Magdeburg, Germany
| | - Jordi Heijman
- Institute of Pharmacology, West German Heart and Vascular Center, University Duisburg-Essen, Essen, Germany.,Cardiovascular Research Institute Maastricht, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Jens Kockskämper
- Biochemical and Pharmacological Center (BPC) Marburg, Institute of Pharmacology and Clinical Pharmacy, University of Marburg, Marburg, Germany
| | - Dominik Linz
- Centre for Heart Rhythm Disorders, South Australian Health and Medical Research Institute, University of Adelaide and Royal Adelaide Hospital, Adelaide, SA, Australia.,Experimental Electrophysiology, University Hospital of Saarland, Homburg, Saar, Germany
| | - Katja E Odening
- Department of Cardiology and Angiology I, Heart Center University of Freiburg, Freiburg, Germany.,Faculty of Medicine, University of Freiburg, Freiburg, Germany.,Institute for Experimental Cardiovascular Medicine, Heart Center University of Freiburg, Freiburg, Germany
| | - Patrick A Schweizer
- Department of Cardiology, Medical University Hospital, Im Neuenheimer Feld 410, 69120, Heidelberg, Germany.,HCR (Heidelberg Center for Heart Rhythm Disorders), Heidelberg, Germany.,DZHK (German Center for Cardiovascular Research), partner site Heidelberg/Mannheim, Heidelberg, Germany.,Heidelberg Research Center for Molecular Medicine (HRCMM), Heidelberg, Germany
| | - Reza Wakili
- Department of Cardiology and Vascular Medicine, Medical Faculty, West German Heart Center, University Hospital Essen, Essen, Germany
| | - Niels Voigt
- Institute of Pharmacology and Toxicology, University Medical Center Göttingen, Georg-August University Göttingen, Robert-Koch-Straße 40, 37075, Göttingen, Germany. .,DZHK (German Center for Cardiovascular Research), partner site Göttingen, Göttingen, Germany.
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22
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Brandenburg S, Pawlowitz J, Fakuade FE, Kownatzki-Danger D, Kohl T, Mitronova GY, Scardigli M, Neef J, Schmidt C, Wiedmann F, Pavone FS, Sacconi L, Kutschka I, Sossalla S, Moser T, Voigt N, Lehnart SE. Axial Tubule Junctions Activate Atrial Ca 2+ Release Across Species. Front Physiol 2018; 9:1227. [PMID: 30349482 PMCID: PMC6187065 DOI: 10.3389/fphys.2018.01227] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Accepted: 08/14/2018] [Indexed: 01/10/2023] Open
Abstract
Rationale: Recently, abundant axial tubule (AT) membrane structures were identified deep inside atrial myocytes (AMs). Upon excitation, ATs rapidly activate intracellular Ca2+ release and sarcomeric contraction through extensive AT junctions, a cell-specific atrial mechanism. While AT junctions with the sarcoplasmic reticulum contain unusually large clusters of ryanodine receptor 2 (RyR2) Ca2+ release channels in mouse AMs, it remains unclear if similar protein networks and membrane structures exist across species, particularly those relevant for atrial disease modeling. Objective: To examine and quantitatively analyze the architecture of AT membrane structures and associated Ca2+ signaling proteins across species from mouse to human. Methods and Results: We developed superresolution microscopy (nanoscopy) strategies for intact live AMs based on a new custom-made photostable cholesterol dye and immunofluorescence imaging of membraneous structures and membrane proteins in fixed tissue sections from human, porcine, and rodent atria. Consistently, in mouse, rat, and rabbit AMs, intact cell-wide tubule networks continuous with the surface membrane were observed, mainly composed of ATs. Moreover, co-immunofluorescence nanoscopy showed L-type Ca2+ channel clusters adjacent to extensive junctional RyR2 clusters at ATs. However, only junctional RyR2 clusters were highly phosphorylated and may thus prime Ca2+ release at ATs, locally for rapid signal amplification. While the density of the integrated L-type Ca2+ current was similar in human and mouse AMs, the intracellular Ca2+ transient showed quantitative differences. Importantly, local intracellular Ca2+ release from AT junctions occurred through instantaneous action potential propagation via transverse tubules (TTs) from the surface membrane. Hence, sparse TTs were sufficient as electrical conduits for rapid activation of Ca2+ release through ATs. Nanoscopy of atrial tissue sections confirmed abundant ATs as the major network component of AMs, particularly in human atrial tissue sections. Conclusion: AT junctions represent a conserved, cell-specific membrane structure for rapid excitation-contraction coupling throughout a representative spectrum of species including human. Since ATs provide the major excitable membrane network component in AMs, a new model of atrial “super-hub” Ca2+ signaling may apply across biomedically relevant species, opening avenues for future investigations about atrial disease mechanisms and therapeutic targeting.
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Affiliation(s)
- Sören Brandenburg
- Heart Research Center Göttingen, Department of Cardiology and Pneumology, University Medical Center Göttingen, Göttingen, Germany
| | - Jan Pawlowitz
- Heart Research Center Göttingen, Department of Cardiology and Pneumology, University Medical Center Göttingen, Göttingen, Germany
| | - Funsho E Fakuade
- Heart Research Center Göttingen, Institute of Pharmacology and Toxicology, University Medical Center Göttingen, Göttingen, Germany
| | - Daniel Kownatzki-Danger
- Heart Research Center Göttingen, Department of Cardiology and Pneumology, University Medical Center Göttingen, Göttingen, Germany
| | - Tobias Kohl
- Heart Research Center Göttingen, Department of Cardiology and Pneumology, University Medical Center Göttingen, Göttingen, Germany
| | - Gyuzel Y Mitronova
- Department of NanoBiophotonics, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Marina Scardigli
- European Laboratory for Non-Linear Spectroscopy and National Institute of Optics (INO-CNR), Sesto Fiorentino, Italy
| | - Jakob Neef
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany
| | - Constanze Schmidt
- Heart Research Center Göttingen, Department of Cardiology and Pneumology, University Medical Center Göttingen, Göttingen, Germany.,DZHK (German Centre for Cardiovascular Research) partner site Heidelberg/Mannheim, University of Heidelberg, Heidelberg, Germany.,Heidelberg Center for Heart Rhythm Disorders, University Hospital Heidelberg, Heidelberg, Germany
| | - Felix Wiedmann
- Department of Cardiology, University Hospital Heidelberg, Heidelberg, Germany.,DZHK (German Centre for Cardiovascular Research) partner site Heidelberg/Mannheim, University of Heidelberg, Heidelberg, Germany.,Heidelberg Center for Heart Rhythm Disorders, University Hospital Heidelberg, Heidelberg, Germany
| | - Francesco S Pavone
- European Laboratory for Non-Linear Spectroscopy and National Institute of Optics (INO-CNR), Sesto Fiorentino, Italy.,Department of Physics, University of Florence, Florence, Italy
| | - Leonardo Sacconi
- European Laboratory for Non-Linear Spectroscopy and National Institute of Optics (INO-CNR), Sesto Fiorentino, Italy
| | - Ingo Kutschka
- Department of Cardiothoracic and Vascular Surgery, University Medical Center Göttingen, Göttingen, Germany
| | - Samuel Sossalla
- Heart Research Center Göttingen, Department of Cardiology and Pneumology, University Medical Center Göttingen, Göttingen, Germany
| | - Tobias Moser
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany
| | - Niels Voigt
- Heart Research Center Göttingen, Institute of Pharmacology and Toxicology, University Medical Center Göttingen, Göttingen, Germany.,DZHK (German Centre for Cardiovascular Research) partner site Göttingen, Göttingen, Germany
| | - Stephan E Lehnart
- Heart Research Center Göttingen, Department of Cardiology and Pneumology, University Medical Center Göttingen, Göttingen, Germany.,DZHK (German Centre for Cardiovascular Research) partner site Göttingen, Göttingen, Germany.,BioMET, The Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD, United States
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23
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Modification of levosimendan-induced suppression of atrial natriuretic peptide secretion in hypertrophied rat atria. Eur J Pharmacol 2018; 829:54-62. [PMID: 29653089 DOI: 10.1016/j.ejphar.2018.04.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Revised: 04/05/2018] [Accepted: 04/09/2018] [Indexed: 10/17/2022]
Abstract
This study aimed to determine the effects of levosimendan, a calcium sensitizer, on atrial contractility and atrial natriuretic peptide (ANP) secretion and its modification in hypertrophied atria. Isolated perfused beating rat atria were used from control and isoproterenol-treated rats. Levosimendan and its metabolite OR-1896 caused a positive inotropic effect and suppressed ANP secretion in rat atria. Similar to levosimendan, the selective phosphodiesterase 3 (PDE3) or PDE4 inhibitor also suppressed ANP secretion. Suppression of ANP secretion by 1 µM levosimendan was abolished by PDE3 inhibitor, but reversed by PDE4 inhibitor. Levosimendan-induced suppression of ANP secretion was potentiated by KATP channel blocker, but blocked by KATP channel opener. Levosimendan alone did not significantly change cyclic adenosine monophosphate (cAMP) efflux in the perfusate; however, levosimendan combined with PDE4 inhibitor markedly increased this efflux. The stimulation of ANP secretion induced by levosimendan combined with PDE4 inhibitor was blocked by the protein kinase A (PKA) inhibitor. In isoproterenol-treated atria, levosimendan augmented the positive inotropic effect and ANP secretion in response to an increased extracellular calcium concentration ([Ca+]o). These results suggests that levosimendan suppresses ANP secretion by both inhibiting PDE3 and opening KATP channels and that levosimendan combined with PDE4 inhibitor stimulates ANP secretion by activating the cAMP-PKA pathway. Modification of the effects of levosimendan on [Ca+]o-induced positive inotropic effects and ANP secretion in isoproterenol-treated rat atria might be related to a disturbance in calcium metabolism.
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24
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Carrera C, Jiménez-Conde J, Derdak S, Rabionet K, Vives-Bauzá C, Soriano-Tárrega C, Giralt-Steinhauer E, Mola-Caminal M, Diaz-Navarro RM, Tur S, Muiño E, Gallego-Fabrega C, Beltran S, Roquer J, Ruiz A, Sotolongo-Grau O, Krupinski J, Lee JM, Cruchaga C, Delgado P, Malik R, Worrall BB, Seshadri S, Montaner J, Fernández-Cadenas I. Whole exome sequencing analysis reveals TRPV3 as a risk factor for cardioembolic stroke/subtitle. Thromb Haemost 2018; 116:1165-1171. [DOI: 10.1160/th16-02-0113] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Accepted: 08/15/2016] [Indexed: 12/12/2022]
Abstract
SummaryGenetic studies suggest that hundreds of genes associated with stroke remain unidentified. Exome sequencing proves useful for finding new genes associated with stroke. We aimed to find new genetic risk factors for cardioembolic stroke by analysing exome sequence data using new strategies. For discovery, we analysed 42 cardioembolic stroke cases and controls with extreme phenotypes (cohort 1), and for replication, 32 cardioembolic stroke cases and controls (cohort 2) using the SeqCapExome capture kit. We then analysed the replicated genes in two new cohorts that comprised 834 cardioembolic strokes and controls (cohort 3) and 64,373 cardioembolic strokes and controls (cohort 4). Transcriptomic in-silico functional analyses were also performed. We found 26 coding regions with a higher frequency of mutations in cardioembolic strokes after correcting for the number of mutations found in the whole exome of every patient. The TRPV3 gene was associated with cardioembolic stroke after replication of exome sequencing analysis (p-value-discovery: 0.018, p-value-replication: 0.014). The analysis of the TRPV3 gene using polymorphisms in cohort 3 and 4 revealed two polymorphisms associated with cardioembolic stroke in both cohorts, the most significant polymorphism being rs151091899 (p-value: 3.1 × 10−05; odds ratio: 5.4) in cohort 3. The genotype of one polymorphism of TRPV3 was associated with a differential expression of genes linked to cardiac malformations. In conclusion, new strategies using exome sequence data have revealed TRPV3 as a new gene associated with cardioembolic stroke. This strategy among others might be useful in finding new genes associated with complex genetic diseases.
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25
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Probucol prevents atrial ion channel remodeling in an alloxan-induced diabetes rabbit model. Oncotarget 2018; 7:83850-83858. [PMID: 27863381 PMCID: PMC5356629 DOI: 10.18632/oncotarget.13339] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Accepted: 11/09/2016] [Indexed: 12/21/2022] Open
Abstract
Diabetes mellitus (DM) increases the risk of developing atrial fibrillation (AF), but the molecular mechanisms of diabetes-induced atrial remodeling processes have not been fully characterized. The aim of this study was to examine the mechanisms underlying atrial ion channel remodeling in alloxan-induced diabetes model in rabbits. A total of 40 Japanese rabbits were randomly assigned to a control group (C), alloxan-induced diabetic group (DM), probucol-treated control group (Control-P), and probucol-treated diabetic group (DM-P). Using whole-cell voltage-clamp techniques, ICa,L, INa and action potential durations (APDs) were measured in cardiomyocytes isolated from the left atria in the four groups, respectively. In the DM group, increased Ica,L and decreased INa currents were reflected in prolonged APD90 and APD50 values. These changes were reversed in the DM-P group. In conclusion, probucol cured AF by alleviating the ion channel remodeling of atrial myocytes in the setting of diabetes and the promising therapeutic potential of anti-oxidative compounds in the treatment of AF warrants further study.
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26
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Schweitzer MK, Wilting F, Sedej S, Dreizehnter L, Dupper NJ, Tian Q, Moretti A, My I, Kwon O, Priori SG, Laugwitz KL, Storch U, Lipp P, Breit A, Mederos y Schnitzler M, Gudermann T, Schredelseker J. Suppression of Arrhythmia by Enhancing Mitochondrial Ca 2+ Uptake in Catecholaminergic Ventricular Tachycardia Models. JACC Basic Transl Sci 2017; 2:737-747. [PMID: 29354781 PMCID: PMC5774336 DOI: 10.1016/j.jacbts.2017.06.008] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Revised: 06/26/2017] [Accepted: 06/27/2017] [Indexed: 11/30/2022]
Abstract
Cardiovascular disease-related deaths frequently arise from arrhythmias, but treatment options are limited due to perilous side effects of commonly used antiarrhythmic drugs. Cardiac rhythmicity strongly depends on cardiomyocyte Ca2+ handling and prevalent cardiac diseases are causally associated with perturbations in intracellular Ca2+ handling. Therefore, intracellular Ca2+ transporters are lead candidate structures for novel and safer antiarrhythmic therapies. Mitochondria and mitochondrial Ca2+ transport proteins are important regulators of cardiac Ca2+ handling. Here we evaluated the potential of pharmacological activation of mitochondrial Ca2+ uptake for the treatment of cardiac arrhythmia. To this aim,we tested substances that enhance mitochondrial Ca2+ uptake for their ability to suppress arrhythmia in a murine model for ryanodine receptor 2 (RyR2)-mediated catecholaminergic polymorphic ventricular tachycardia (CPVT) in vitro and in vivo and in induced pluripotent stem cell-derived cardiomyocytes from a CPVT patient. In freshly isolated cardiomyocytes of RyR2R4496C/WT mice efsevin, a synthetic agonist of the voltage-dependent anion channel 2 (VDAC2) in the outer mitochondrial membrane, prevented the formation of diastolic Ca2+ waves and spontaneous action potentials. The antiarrhythmic effect of efsevin was abolished by blockade of the mitochondrial Ca2+ uniporter (MCU), but could be reproduced using the natural MCU activator kaempferol. Both mitochondrial Ca2+ uptake enhancers (MiCUps), efsevin and kaempferol, significantly reduced episodes of stress-induced ventricular tachycardia in RyR2R4496C/WT mice in vivo and abolished diastolic, arrhythmogenic Ca2+ events in human iPSC-derived cardiomyocytes.
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Affiliation(s)
- Maria K. Schweitzer
- Walther Straub Institute of Pharmacology and Toxicology, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Fabiola Wilting
- Walther Straub Institute of Pharmacology and Toxicology, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Simon Sedej
- Department of Cardiology, Medical University of Graz, Graz, Austria
| | - Lisa Dreizehnter
- Department of Medicine (Cardiology), Klinikum rechts der Isar, Technische Universität München, Munich, Germany
| | - Nathan J. Dupper
- Department of Chemistry and Biochemistry, University of California Los Angeles, Los Angeles, California
| | - Qinghai Tian
- Institute for Molecular Cell Biology, University Medical Center, Saarland University, Homburg/Saar, Germany
| | - Alessandra Moretti
- Department of Medicine (Cardiology), Klinikum rechts der Isar, Technische Universität München, Munich, Germany
- Deutsches Zentrum für Herz-Kreislauf-Forschung, Partner Site Munich Heart Alliance, Munich, Germany
| | - Ilaria My
- Department of Medicine (Cardiology), Klinikum rechts der Isar, Technische Universität München, Munich, Germany
| | - Ohyun Kwon
- Department of Chemistry and Biochemistry, University of California Los Angeles, Los Angeles, California
| | - Silvia G. Priori
- Molecular Cardiology, Istituto di ricovero e cura a carattere scientifico (IRCCS) Salvatore Maugeri Foundation, Pavia, Italy
- Department of Molecular Medicine, University of Pavia, Pavia, Italy
| | - Karl-Ludwig Laugwitz
- Department of Medicine (Cardiology), Klinikum rechts der Isar, Technische Universität München, Munich, Germany
- Deutsches Zentrum für Herz-Kreislauf-Forschung, Partner Site Munich Heart Alliance, Munich, Germany
| | - Ursula Storch
- Walther Straub Institute of Pharmacology and Toxicology, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Peter Lipp
- Institute for Molecular Cell Biology, University Medical Center, Saarland University, Homburg/Saar, Germany
| | - Andreas Breit
- Walther Straub Institute of Pharmacology and Toxicology, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Michael Mederos y Schnitzler
- Walther Straub Institute of Pharmacology and Toxicology, Ludwig-Maximilians-Universität München, Munich, Germany
- Deutsches Zentrum für Herz-Kreislauf-Forschung, Partner Site Munich Heart Alliance, Munich, Germany
| | - Thomas Gudermann
- Walther Straub Institute of Pharmacology and Toxicology, Ludwig-Maximilians-Universität München, Munich, Germany
- Deutsches Zentrum für Herz-Kreislauf-Forschung, Partner Site Munich Heart Alliance, Munich, Germany
| | - Johann Schredelseker
- Walther Straub Institute of Pharmacology and Toxicology, Ludwig-Maximilians-Universität München, Munich, Germany
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27
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Wiersma M, Meijering RAM, Qi XY, Zhang D, Liu T, Hoogstra-Berends F, Sibon OCM, Henning RH, Nattel S, Brundel BJJM. Endoplasmic Reticulum Stress Is Associated With Autophagy and Cardiomyocyte Remodeling in Experimental and Human Atrial Fibrillation. J Am Heart Assoc 2017; 6:JAHA.117.006458. [PMID: 29066441 PMCID: PMC5721854 DOI: 10.1161/jaha.117.006458] [Citation(s) in RCA: 74] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Background Derailment of proteostasis, the homeostasis of production, function, and breakdown of proteins, contributes importantly to the self‐perpetuating nature of atrial fibrillation (AF), the most common heart rhythm disorder in humans. Autophagy plays an important role in proteostasis by degrading aberrant proteins and organelles. Herein, we investigated the role of autophagy and its activation pathway in experimental and clinical AF. Methods and Results Tachypacing of HL‐1 atrial cardiomyocytes causes a gradual and significant activation of autophagy, as evidenced by enhanced LC3B‐II expression, autophagic flux and autophagosome formation, and degradation of p62, resulting in reduction of Ca2+ amplitude. Autophagy is activated downstream of endoplasmic reticulum (ER) stress: blocking ER stress by the chemical chaperone 4‐phenyl butyrate, overexpression of the ER chaperone‐protein heat shock protein A5, or overexpression of a phosphorylation‐blocked mutant of eukaryotic initiation factor 2α (eIF2α) prevents autophagy activation and Ca2+‐transient loss in tachypaced HL‐1 cardiomyocytes. Moreover, pharmacological inhibition of ER stress in tachypaced Drosophila confirms its role in derailing cardiomyocyte function. In vivo treatment with sodium salt of phenyl butyrate protected atrial‐tachypaced dog cardiomyocytes from electrical remodeling (action potential duration shortening, L‐type Ca2+‐current reduction), cellular Ca2+‐handling/contractile dysfunction, and ER stress and autophagy; it also attenuated AF progression. Finally, atrial tissue from patients with persistent AF reveals activation of autophagy and induction of ER stress, which correlates with markers of cardiomyocyte damage. Conclusions These results identify ER stress–associated autophagy as an important pathway in AF progression and demonstrate the potential therapeutic action of the ER‐stress inhibitor 4‐phenyl butyrate.
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Affiliation(s)
- Marit Wiersma
- Department of Physiology, Amsterdam Cardiovascular Sciences, VU University Medical Center, Amsterdam, The Netherlands
- Department of Clinical Pharmacy and Pharmacology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Roelien A M Meijering
- Department of Clinical Pharmacy and Pharmacology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Xiao-Yan Qi
- Department of Medicine, Montreal Heart Institute and Université de Montréal, the Department of Pharmacology and Therapeutics, McGill University, Montreal, Québec, Canada
- Institute of Pharmacology, West German Heart and Vascular Center, Faculty of Medicine, University of Duisburg-Essen, Duisburg, Germany
| | - Deli Zhang
- Department of Physiology, Amsterdam Cardiovascular Sciences, VU University Medical Center, Amsterdam, The Netherlands
- Department of Clinical Pharmacy and Pharmacology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Tao Liu
- Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, China
| | - Femke Hoogstra-Berends
- Department of Clinical Pharmacy and Pharmacology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Ody C M Sibon
- Department of Cell Biology, University Medical Center Groningen, University of Groningen, The Netherlands
| | - Robert H Henning
- Department of Clinical Pharmacy and Pharmacology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Stanley Nattel
- Department of Medicine, Montreal Heart Institute and Université de Montréal, the Department of Pharmacology and Therapeutics, McGill University, Montreal, Québec, Canada
- Institute of Pharmacology, West German Heart and Vascular Center, Faculty of Medicine, University of Duisburg-Essen, Duisburg, Germany
| | - Bianca J J M Brundel
- Department of Physiology, Amsterdam Cardiovascular Sciences, VU University Medical Center, Amsterdam, The Netherlands
- Department of Clinical Pharmacy and Pharmacology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
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28
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Greiser M. Calcium signalling silencing in atrial fibrillation. J Physiol 2017; 595:4009-4017. [PMID: 28332202 DOI: 10.1113/jp273045] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Accepted: 01/05/2017] [Indexed: 01/19/2023] Open
Abstract
Subcellular calcium signalling silencing is a novel and distinct cellular and molecular adaptive response to rapid cardiac activation. Calcium signalling silencing develops during short-term sustained rapid atrial activation as seen clinically during paroxysmal atrial fibrillation (AF). It is the first 'anti-arrhythmic' adaptive response in the setting of AF and appears to counteract the maladaptive changes that lead to intracellular Ca2+ signalling instability and Ca2+ -based arrhythmogenicity. Calcium signalling silencing results in a failed propagation of the [Ca2+ ]i signal to the myocyte centre both in patients with AF and in a rabbit model. This adaptive mechanism leads to a substantial reduction in the expression levels of calcium release channels (ryanodine receptors, RyR2) in the sarcoplasmic reticulum, and the frequency of Ca2+ sparks and arrhythmogenic Ca2+ waves remains low. Less Ca2+ release per [Ca2+ ]i transient, increased fast Ca2+ buffering strength, shortened action potentials and reduced L-type Ca2+ current contribute to a substantial reduction of intracellular [Na+ ]. These features of Ca2+ signalling silencing are distinct and in contrast to the changes attributed to Ca2+ -based arrhythmogenicity. Some features of Ca2+ signalling silencing prevail in human AF suggesting that the Ca2+ signalling 'phenotype' in AF is a sum of Ca2+ stabilizing (Ca2+ signalling silencing) and Ca2+ destabilizing (arrhythmogenic unstable Ca2+ signalling) factors. Calcium signalling silencing is a part of the mechanisms that contribute to the natural progression of AF and may limit the role of Ca2+ -based arrhythmogenicity after the onset of AF.
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Affiliation(s)
- Maura Greiser
- Center for Biomedical Engineering and Technology and Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA
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29
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Bond RC, Bryant SM, Watson JJ, Hancox JC, Orchard CH, James AF. Reduced density and altered regulation of rat atrial L-type Ca 2+ current in heart failure. Am J Physiol Heart Circ Physiol 2017; 312:H384-H391. [PMID: 27923791 PMCID: PMC5402008 DOI: 10.1152/ajpheart.00528.2016] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/27/2016] [Revised: 11/21/2016] [Accepted: 11/23/2016] [Indexed: 11/22/2022]
Abstract
Constitutive regulation by PKA has recently been shown to contribute to L-type Ca2+ current (ICaL) at the ventricular t-tubule in heart failure. Conversely, reduction in constitutive regulation by PKA has been proposed to underlie the downregulation of atrial ICaL in heart failure. The hypothesis that downregulation of atrial ICaL in heart failure involves reduced channel phosphorylation was examined. Anesthetized adult male Wistar rats underwent surgical coronary artery ligation (CAL, N=10) or equivalent sham-operation (Sham, N=12). Left atrial myocytes were isolated ~18 wk postsurgery and whole cell currents recorded (holding potential=-80 mV). ICaL activated by depolarizing pulses to voltages from -40 to +50 mV were normalized to cell capacitance and current density-voltage relations plotted. CAL cell capacitances were ~1.67-fold greater than Sham (P ≤ 0.0001). Maximal ICaL conductance (Gmax ) was downregulated more than 2-fold in CAL vs. Sham myocytes (P < 0.0001). Norepinephrine (1 μmol/l) increased Gmax >50% more effectively in CAL than in Sham so that differences in ICaL density were abolished. Differences between CAL and Sham Gmax were not abolished by calyculin A (100 nmol/l), suggesting that increased protein dephosphorylation did not account for ICaL downregulation. Treatment with either H-89 (10 μmol/l) or AIP (5 μmol/l) had no effect on basal currents in Sham or CAL myocytes, indicating that, in contrast to ventricular myocytes, neither PKA nor CaMKII regulated basal ICaL Expression of the L-type α1C-subunit, protein phosphatases 1 and 2A, and inhibitor-1 proteins was unchanged. In conclusion, reduction in PKA-dependent regulation did not contribute to downregulation of atrial ICaL in heart failure.NEW & NOTEWORTHY Whole cell recording of L-type Ca2+ currents in atrial myocytes from rat hearts subjected to coronary artery ligation compared with those from sham-operated controls reveals marked reduction in current density in heart failure without change in channel subunit expression and associated with altered phosphorylation independent of protein kinase A.
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Affiliation(s)
- Richard C Bond
- Cardiovascular Research Laboratories, School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, United Kingdom
| | - Simon M Bryant
- Cardiovascular Research Laboratories, School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, United Kingdom
| | - Judy J Watson
- Cardiovascular Research Laboratories, School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, United Kingdom
| | - Jules C Hancox
- Cardiovascular Research Laboratories, School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, United Kingdom
| | - Clive H Orchard
- Cardiovascular Research Laboratories, School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, United Kingdom
| | - Andrew F James
- Cardiovascular Research Laboratories, School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, United Kingdom
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30
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Maxwell JT, Blatter LA. A novel mechanism of tandem activation of ryanodine receptors by cytosolic and SR luminal Ca 2+ during excitation-contraction coupling in atrial myocytes. J Physiol 2017; 595:3835-3845. [PMID: 28028837 DOI: 10.1113/jp273611] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Accepted: 12/01/2016] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS In atrial myocytes excitation-contraction coupling is strikingly different from ventricle because atrial myocytes lack a transverse tubule membrane system: Ca2+ release starts in the cell periphery and propagates towards the cell centre by Ca2+ -induced Ca2+ release from the sarcoplasmic reticulum (SR) Ca2+ store. The cytosolic Ca2+ sensitivity of the ryanodine receptor (RyRs) Ca2+ release channel is low and it is unclear how Ca2+ release can be activated in the interior of atrial cells. Simultaneous confocal imaging of cytosolic and intra-SR calcium revealed a transient elevation of store Ca2+ that we termed 'Ca2+ sensitization signal'. We propose a novel paradigm of atrial ECC that is based on tandem activation of the RyRs by cytosolic and luminal Ca2+ through a 'fire-diffuse-uptake-fire' (or FDUF) mechanism: Ca2+ uptake by SR Ca2+ pumps at the propagation front elevates Ca2+ inside the SR locally, leading to luminal RyR sensitization and lowering of the cytosolic Ca2+ activation threshold. ABSTRACT In atrial myocytes Ca2+ release during excitation-contraction coupling (ECC) is strikingly different from ventricular myocytes. In many species atrial myocytes lack a transverse tubule system, dividing the sarcoplasmic reticulum (SR) Ca2+ store into the peripheral subsarcolemmnal junctional (j-SR) and the much more abundant central non-junctional (nj-SR) SR. Action potential (AP)-induced Ca2+ entry activates Ca2+ -induced Ca2+ release (CICR) from j-SR ryanodine receptor (RyR) Ca2+ release channels. Peripheral elevation of [Ca2+ ]i initiates CICR from nj-SR and sustains propagation of CICR to the cell centre. Simultaneous confocal measurements of cytosolic ([Ca2+ ]i ; with the fluorescent Ca2+ indicator rhod-2) and intra-SR ([Ca2+ ]SR ; fluo-5N) Ca2+ in rabbit atrial myocytes revealed that Ca2+ release from j-SR resulted in a cytosolic Ca2+ transient of higher amplitude compared to release from nj-SR; however, the degree of depletion of j-SR [Ca2+ ]SR was smaller than nj-SR [Ca2+ ]SR . Similarly, Ca2+ signals from individual release sites of the j-SR showed a larger cytosolic amplitude (Ca2+ sparks) but smaller depletion (Ca2+ blinks) than release from nj-SR. During AP-induced Ca2+ release the rise of [Ca2+ ]i detected at individual release sites of the nj-SR preceded the depletion of [Ca2+ ]SR , and during this latency period a transient elevation of [Ca2+ ]SR occurred. We propose that Ca2+ release from nj-SR is activated by cytosolic and luminal Ca2+ (tandem RyR activation) via a novel 'fire-diffuse-uptake-fire' (FDUF) mechanism. This novel paradigm of atrial ECC predicts that Ca2+ uptake by sarco-endoplasmic reticulum Ca2+ -ATPase (SERCA) at the propagation front elevates local [Ca2+ ]SR , leading to luminal RyR sensitization and lowering of the activation threshold for cytosolic CICR.
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Affiliation(s)
- Joshua T Maxwell
- Department of Molecular Biophysics and Physiology, Rush University Medical Centre, Chicago, IL, 60612, USA
| | - Lothar A Blatter
- Department of Molecular Biophysics and Physiology, Rush University Medical Centre, Chicago, IL, 60612, USA
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31
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Arora R, Aistrup GL, Supple S, Frank C, Singh J, Tai S, Zhao A, Chicos L, Marszalec W, Guo A, Song LS, Wasserstrom JA. Regional distribution of T-tubule density in left and right atria in dogs. Heart Rhythm 2016; 14:273-281. [PMID: 27670628 DOI: 10.1016/j.hrthm.2016.09.022] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Indexed: 11/25/2022]
Abstract
BACKGROUND The peculiarities of transverse tubule (T-tubule) morphology and distribution in the atrium-and how they contribute to excitation-contraction coupling-are just beginning to be understood. OBJECTIVES The objectives of this study were to determine T-tubule density in the intact, live right and left atria in a large animal and to determine intraregional differences in T-tubule organization within each atrium. METHODS Using confocal microscopy, T-tubules were imaged in both atria in intact, Langendorf-perfused normal dog hearts loaded with di-4-ANEPPS. T-tubules were imaged in large populations of myocytes from the endocardial surface of each atrium. Computerized data analysis was performed using a new MatLab (Mathworks, Natick, MA) routine, AutoTT. RESULTS There was a large percentage of myocytes that had no T-tubules in both atria with a higher percentage in the right atrium (25.1%) than in the left atrium (12.5%) (P < .02). The density of transverse and longitudinal T-tubule elements was low in cells that did contain T-tubules, but there were no significant differences in density between the left atrial appendage, the pulmonary vein-posterior left atrium, the right atrial appendage, and the right atrial free wall. In contrast, there were significant differences in sarcomere spacing and cell width between different regions of the atria. CONCLUSION There is a sparse T-tubule network in atrial myocytes throughout both dog atria, with significant numbers of myocytes in both atria-the right atrium more so than the left atrium-having no T-tubules at all. These regional differences in T-tubule distribution, along with differences in cell width and sarcomere spacing, may have implications for the emergence of substrate for atrial fibrillation.
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Affiliation(s)
- Rishi Arora
- Division of Cardiology, Department of Medicine, Feinberg Cardiovascular Research Institute, Northwestern University Feinberg School of Medicine, Chicago, Illinois,.
| | - Gary L Aistrup
- Division of Cardiology, Department of Medicine, Feinberg Cardiovascular Research Institute, Northwestern University Feinberg School of Medicine, Chicago, Illinois
| | - Stephen Supple
- Division of Cardiology, Department of Medicine, Feinberg Cardiovascular Research Institute, Northwestern University Feinberg School of Medicine, Chicago, Illinois
| | - Caleb Frank
- Division of Cardiology, Department of Medicine, Feinberg Cardiovascular Research Institute, Northwestern University Feinberg School of Medicine, Chicago, Illinois
| | - Jasleen Singh
- Division of Cardiology, Department of Medicine, Feinberg Cardiovascular Research Institute, Northwestern University Feinberg School of Medicine, Chicago, Illinois
| | - Shannon Tai
- Division of Cardiology, Department of Medicine, Feinberg Cardiovascular Research Institute, Northwestern University Feinberg School of Medicine, Chicago, Illinois
| | - Anne Zhao
- Division of Cardiology, Department of Medicine, Feinberg Cardiovascular Research Institute, Northwestern University Feinberg School of Medicine, Chicago, Illinois
| | - Laura Chicos
- Division of Cardiology, Department of Medicine, Feinberg Cardiovascular Research Institute, Northwestern University Feinberg School of Medicine, Chicago, Illinois
| | - William Marszalec
- Division of Cardiology, Department of Medicine, Feinberg Cardiovascular Research Institute, Northwestern University Feinberg School of Medicine, Chicago, Illinois
| | - Ang Guo
- Division of Cardiology, University of Iowa School of Medicine, Iowa City, Iowa
| | - Long-Sheng Song
- Division of Cardiology, University of Iowa School of Medicine, Iowa City, Iowa
| | - J Andrew Wasserstrom
- Division of Cardiology, Department of Medicine, Feinberg Cardiovascular Research Institute, Northwestern University Feinberg School of Medicine, Chicago, Illinois
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32
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Brandenburg S, Kohl T, Williams GSB, Gusev K, Wagner E, Rog-Zielinska EA, Hebisch E, Dura M, Didié M, Gotthardt M, Nikolaev VO, Hasenfuss G, Kohl P, Ward CW, Lederer WJ, Lehnart SE. Axial tubule junctions control rapid calcium signaling in atria. J Clin Invest 2016; 126:3999-4015. [PMID: 27643434 DOI: 10.1172/jci88241] [Citation(s) in RCA: 95] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Accepted: 08/09/2016] [Indexed: 11/17/2022] Open
Abstract
The canonical atrial myocyte (AM) is characterized by sparse transverse tubule (TT) invaginations and slow intracellular Ca2+ propagation but exhibits rapid contractile activation that is susceptible to loss of function during hypertrophic remodeling. Here, we have identified a membrane structure and Ca2+-signaling complex that may enhance the speed of atrial contraction independently of phospholamban regulation. This axial couplon was observed in human and mouse atria and is composed of voluminous axial tubules (ATs) with extensive junctions to the sarcoplasmic reticulum (SR) that include ryanodine receptor 2 (RyR2) clusters. In mouse AM, AT structures triggered Ca2+ release from the SR approximately 2 times faster at the AM center than at the surface. Rapid Ca2+ release correlated with colocalization of highly phosphorylated RyR2 clusters at AT-SR junctions and earlier, more rapid shortening of central sarcomeres. In contrast, mice expressing phosphorylation-incompetent RyR2 displayed depressed AM sarcomere shortening and reduced in vivo atrial contractile function. Moreover, left atrial hypertrophy led to AT proliferation, with a marked increase in the highly phosphorylated RyR2-pS2808 cluster fraction, thereby maintaining cytosolic Ca2+ signaling despite decreases in RyR2 cluster density and RyR2 protein expression. AT couplon "super-hubs" thus underlie faster excitation-contraction coupling in health as well as hypertrophic compensatory adaptation and represent a structural and metabolic mechanism that may contribute to contractile dysfunction and arrhythmias.
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33
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LIU SHUENHSIN, HSIAO YAWEN, CHONG ERIC, SINGHAL RAHUL, FONG MANCAI, TSAI YUNGNAN, HSU CHIAOPO, CHEN YAOCHANG, CHEN YIJEN, CHIOU CHUENWANG, CHIANG SHUOJU, CHANG SHIHLIN, CHEN SHIHANN. Rhodiola Inhibits Atrial Arrhythmogenesis in a Heart Failure Model. J Cardiovasc Electrophysiol 2016; 27:1093-101. [DOI: 10.1111/jce.13026] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Revised: 05/12/2016] [Accepted: 05/16/2016] [Indexed: 12/01/2022]
Affiliation(s)
- SHUEN-HSIN LIU
- Division of Cardiology, Department of Medicine, Shuang-Ho Hospital; Taipei Medical University; New Taipei City Taiwan
| | - YA-WEN HSIAO
- Division of Cardiology; Taipei Veterans General Hospital; Taipei Taiwan
| | - ERIC CHONG
- Division of Cardiology, Department of Medicine; Alexandra Hospital; Jurong Health Singapore
| | - RAHUL SINGHAL
- Department of Electrophysiology and Cardiac Pacing; Heart and General Hospital; India
| | - MAN-CAI FONG
- Division of Cardiovascular Medicine; Cheng Hsin General Hospital; Taipei Taiwan
| | - YUNG-NAN TSAI
- Division of Cardiology; Taipei Veterans General Hospital; Taipei Taiwan
- Department of Medicine; National Yang-Ming University School of Medicine; Taipei Taiwan
| | - CHIAO-PO HSU
- Department of Medicine; National Yang-Ming University School of Medicine; Taipei Taiwan
- Division of Cardiovascular Surgery; Taipei Veterans General Hospital; Taipei Taiwan
| | - YAO-CHANG CHEN
- Department of Biomedical Engineering; National Defense Medical Center; Taipei Taiwan
| | - YI-JEN CHEN
- Graduate Institute of Clinical Medicine, College of Medicine; Taipei Medical University; Taipei Taiwan
- Division of Cardiovascular Medicine, Department of Internal Medicine, Wan-Fang Hospital; Taipei Medical University; Taipei Taiwan
| | - CHUEN-WANG CHIOU
- Division of Cardiology; Taipei Veterans General Hospital; Taipei Taiwan
- Department of Medicine; National Yang-Ming University School of Medicine; Taipei Taiwan
| | - SHUO-JU CHIANG
- Division of Cardiology, Department of Internal Medicine, School of Medicine, College of Medicine; Taipei Medical University; Taipei Taiwan
| | - SHIH-LIN CHANG
- Division of Cardiology; Taipei Veterans General Hospital; Taipei Taiwan
- Department of Medicine; National Yang-Ming University School of Medicine; Taipei Taiwan
| | - SHIH-ANN CHEN
- Division of Cardiology; Taipei Veterans General Hospital; Taipei Taiwan
- Department of Medicine; National Yang-Ming University School of Medicine; Taipei Taiwan
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34
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Gadeberg HC, Bond RC, Kong CHT, Chanoit GP, Ascione R, Cannell MB, James AF. Heterogeneity of T-Tubules in Pig Hearts. PLoS One 2016; 11:e0156862. [PMID: 27281038 PMCID: PMC4900646 DOI: 10.1371/journal.pone.0156862] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2014] [Accepted: 04/30/2016] [Indexed: 12/15/2022] Open
Abstract
Background T-tubules are invaginations of the sarcolemma that play a key role in excitation-contraction coupling in mammalian cardiac myocytes. Although t-tubules were generally considered to be effectively absent in atrial myocytes, recent studies on atrial cells from larger mammals suggest that t-tubules may be more numerous than previously supposed. However, the degree of heterogeneity between cardiomyocytes in the extent of the t-tubule network remains unclear. The aim of the present study was to investigate the t-tubule network of pig atrial myocytes in comparison with ventricular tissue. Methods Cardiac tissue was obtained from young female Landrace White pigs (45–75 kg, 5–6 months old). Cardiomyocytes were isolated by arterial perfusion with a collagenase-containing solution. Ca2+ transients were examined in field-stimulated isolated cells loaded with fluo-4-AM. Membranes of isolated cells were visualized using di-8-ANEPPS. T-tubules were visualized in fixed-frozen tissue sections stained with Alexa-Fluor 488-conjugated WGA. Binary images were obtained by application of a threshold and t-tubule density (TTD) calculated. A distance mapping approach was used to calculate half-distance to nearest t-tubule (HDTT). Results & Conclusion The spatio-temporal properties of the Ca2+ transient appeared to be consistent with the absence of functional t-tubules in isolated atrial myocytes. However, t-tubules could be identified in a sub-population of atrial cells in frozen sections. While all ventricular myocytes had TTD >3% (mean TTD = 6.94±0.395%, n = 24), this was true of just 5/22 atrial cells. Mean atrial TTD (2.35±0.457%, n = 22) was lower than ventricular TTD (P<0.0001). TTD correlated with cell-width (r = 0.7756, n = 46, P<0.0001). HDTT was significantly greater in the atrial cells with TTD ≤3% (2.29±0.16 μm, n = 17) than in either ventricular cells (1.33±0.05 μm, n = 24, P<0.0001) or in atrial cells with TTD >3% (1.65±0.06 μm, n = 5, P<0.05). These data demonstrate considerable heterogeneity between pig cardiomyocytes in the extent of t-tubule network, which correlated with cell size.
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Affiliation(s)
- Hanne C. Gadeberg
- Cardiovascular Research Laboratories, Bristol Cardiovascular, School of Physiology, Pharmacology & Neuroscience, University of Bristol, Bristol, BS8 1TD, United Kingdom
| | - Richard C. Bond
- Cardiovascular Research Laboratories, Bristol Cardiovascular, School of Physiology, Pharmacology & Neuroscience, University of Bristol, Bristol, BS8 1TD, United Kingdom
| | - Cherrie H. T. Kong
- Cardiovascular Research Laboratories, Bristol Cardiovascular, School of Physiology, Pharmacology & Neuroscience, University of Bristol, Bristol, BS8 1TD, United Kingdom
| | - Guillaume P. Chanoit
- School of Veterinary Sciences, University of Bristol, Langford House, Langford, BS40 5DU, United Kingdom
| | - Raimondo Ascione
- School of Clinical Sciences, University of Bristol, Bristol Royal Infirmary, Upper Maudlin Street, Bristol, BS2 8HW, United Kingdom
| | - Mark B. Cannell
- Cardiovascular Research Laboratories, Bristol Cardiovascular, School of Physiology, Pharmacology & Neuroscience, University of Bristol, Bristol, BS8 1TD, United Kingdom
- * E-mail: (AFJ); (MBC)
| | - Andrew F. James
- Cardiovascular Research Laboratories, Bristol Cardiovascular, School of Physiology, Pharmacology & Neuroscience, University of Bristol, Bristol, BS8 1TD, United Kingdom
- * E-mail: (AFJ); (MBC)
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Yang S, Xu W, Dong Z, Zhou M, Lin C, Jin H, Su Y, Li Q, Wang X, Chang H, Han W. TPEN prevents rapid pacing-induced calcium overload and nitration stress in HL-1 myocytes. Cardiovasc Ther 2016; 33:200-8. [PMID: 25973665 DOI: 10.1111/1755-5922.12134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
INTRODUCTION Atrial fibrillation (AF) is the most common cardiac arrhythmia. However, the current drug interference of antiarrhythmia has limited efficacy and off-target effects. Accumulating evidence has implicated a potential role of nitration stress in the pathogenesis of AF. The aim of the study was to determine whether TPEN provided antinitration effects on atrial myocytes during AF, especially under circumstances of nitration stress. METHODS We utilized a rapid paced HL-1 cells model for AF. The changes of electrophysiological characteristics and structure of paced HL-1 cells were determined by a patch clamp and a TEM method. The effects of TPEN on pacing and ONOO(-) pretreated HL-1 cells were examined using MTT assay, TUNEL technique, confocal microscope experiment, and Western blot analysis. RESULTS The results revealed that ONOO(-) reduced the viability of HL-1 cells in a dose-dependent manner, and 1 μmol/L TPEN significantly ameliorated the damage caused by 50 μmol/L ONOO(-) (P < 0.05). Pacing and/or ONOO(-) -induced marked shortening of APD, myolysis, and nuclear condensation. TPEN inhibited the Ca(2+) overload induced by rapid pacing (P < 0.05) and ONOO(-) stimulation (P < 0.05). The application of TPEN significantly prevented the protein nitration caused by pacing or pacing plus ONOO(-) (P < 0.05). Additionally, pacing in combination with ONOO(-) treatment led to increase in apoptosis in HL-1 cells (P < 0.01), which could be reduced by pretreatment with TPEN (P < 0.05). CONCLUSIONS TPEN prevents Ca(2+) overload and nitration stress in HL-1 atrial myocytes during rapid pacing and circumstances of nitration stress.
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Affiliation(s)
- Shusen Yang
- Department of Cardiology, The First Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Wenjing Xu
- Department of Cardiology, The First Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Zengxiang Dong
- Department of Cardiology, The First Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Mo Zhou
- Department of Cardiology, The First Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Chaolan Lin
- Department of Cardiology, The First Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Hongbo Jin
- Laboratory of Physiology, Harbin Medical University, Harbin, China
| | - Yafen Su
- Department of Cardiology, The First Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Qingyu Li
- Department of Cardiology, The First Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Xu Wang
- Department of Cardiology, The First Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Huiying Chang
- Department of Cardiology, The First Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Wei Han
- Department of Cardiology, The First Affiliated Hospital of Harbin Medical University, Harbin, China
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36
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Hua R, MacLeod SL, Polina I, Moghtadaei M, Jansen HJ, Bogachev O, O’Blenes SB, Sapp JL, Legare JF, Rose RA. Effects of Wild-Type and Mutant Forms of Atrial Natriuretic Peptide on Atrial Electrophysiology and Arrhythmogenesis. Circ Arrhythm Electrophysiol 2015; 8:1240-54. [DOI: 10.1161/circep.115.002896] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Accepted: 07/10/2015] [Indexed: 11/16/2022]
Abstract
Background—
Atrial natriuretic peptide (ANP) is a hormone with numerous beneficial cardiovascular effects. Recently, a mutation in the ANP gene, which results in the generation of a mutant form of ANP (mANP), was identified and shown to cause atrial fibrillation in people. The mechanism(s) through which mANP causes atrial fibrillation is unknown. Our objective was to compare the effects of wild-type ANP and mANP on atrial electrophysiology in mice and humans.
Methods and Results—
Action potentials (APs), L-type Ca
2+
currents (
I
Ca,L
), and Na
+
current were recorded in atrial myocytes from wild-type or natriuretic peptide receptor C knockout (NPR-C
−/−
) mice. In mice, ANP and mANP (10–100 nmol/L) had opposing effects on atrial myocyte AP morphology and
I
Ca,L
. ANP increased AP upstroke velocity (
V
max
), AP duration, and
I
Ca,L
similarly in wild-type and NPR-C
−/−
myocytes. In contrast, mANP decreased
V
max
, AP duration, and
I
Ca,L
, and these effects were completely absent in NPR-C
−/−
myocytes. ANP and mANP also had opposing effects on
I
Ca,L
in human atrial myocytes. In contrast, neither ANP nor mANP had any effect on Na
+
current in mouse atrial myocytes. Optical mapping studies in mice demonstrate that ANP sped electric conduction in the atria, whereas mANP did the opposite and slowed atrial conduction. Atrial pacing in the presence of mANP induced arrhythmias in 62.5% of hearts, whereas treatment with ANP completely prevented the occurrence of arrhythmias.
Conclusions—
These findings provide mechanistic insight into how mANP causes atrial fibrillation and demonstrate that wild-type ANP is antiarrhythmic.
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Affiliation(s)
- Rui Hua
- From the Department of Physiology and Biophysics (R.H., S.L.M., I.P., M.M., H.J.J., O.B., S.B.O., J.L.S., R.A.R.), IWK Health Centre (S.B.O.), Department of Surgery (S.B.O., J.-F.L.), Division of Cardiology (J.L.S.), School of Biomedical Engineering (R.A.R.), Faculty of Medicine, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Sarah L. MacLeod
- From the Department of Physiology and Biophysics (R.H., S.L.M., I.P., M.M., H.J.J., O.B., S.B.O., J.L.S., R.A.R.), IWK Health Centre (S.B.O.), Department of Surgery (S.B.O., J.-F.L.), Division of Cardiology (J.L.S.), School of Biomedical Engineering (R.A.R.), Faculty of Medicine, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Iuliia Polina
- From the Department of Physiology and Biophysics (R.H., S.L.M., I.P., M.M., H.J.J., O.B., S.B.O., J.L.S., R.A.R.), IWK Health Centre (S.B.O.), Department of Surgery (S.B.O., J.-F.L.), Division of Cardiology (J.L.S.), School of Biomedical Engineering (R.A.R.), Faculty of Medicine, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Motahareh Moghtadaei
- From the Department of Physiology and Biophysics (R.H., S.L.M., I.P., M.M., H.J.J., O.B., S.B.O., J.L.S., R.A.R.), IWK Health Centre (S.B.O.), Department of Surgery (S.B.O., J.-F.L.), Division of Cardiology (J.L.S.), School of Biomedical Engineering (R.A.R.), Faculty of Medicine, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Hailey J. Jansen
- From the Department of Physiology and Biophysics (R.H., S.L.M., I.P., M.M., H.J.J., O.B., S.B.O., J.L.S., R.A.R.), IWK Health Centre (S.B.O.), Department of Surgery (S.B.O., J.-F.L.), Division of Cardiology (J.L.S.), School of Biomedical Engineering (R.A.R.), Faculty of Medicine, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Oleg Bogachev
- From the Department of Physiology and Biophysics (R.H., S.L.M., I.P., M.M., H.J.J., O.B., S.B.O., J.L.S., R.A.R.), IWK Health Centre (S.B.O.), Department of Surgery (S.B.O., J.-F.L.), Division of Cardiology (J.L.S.), School of Biomedical Engineering (R.A.R.), Faculty of Medicine, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Stacy B. O’Blenes
- From the Department of Physiology and Biophysics (R.H., S.L.M., I.P., M.M., H.J.J., O.B., S.B.O., J.L.S., R.A.R.), IWK Health Centre (S.B.O.), Department of Surgery (S.B.O., J.-F.L.), Division of Cardiology (J.L.S.), School of Biomedical Engineering (R.A.R.), Faculty of Medicine, Dalhousie University, Halifax, Nova Scotia, Canada
| | - John L. Sapp
- From the Department of Physiology and Biophysics (R.H., S.L.M., I.P., M.M., H.J.J., O.B., S.B.O., J.L.S., R.A.R.), IWK Health Centre (S.B.O.), Department of Surgery (S.B.O., J.-F.L.), Division of Cardiology (J.L.S.), School of Biomedical Engineering (R.A.R.), Faculty of Medicine, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Jean-Francois Legare
- From the Department of Physiology and Biophysics (R.H., S.L.M., I.P., M.M., H.J.J., O.B., S.B.O., J.L.S., R.A.R.), IWK Health Centre (S.B.O.), Department of Surgery (S.B.O., J.-F.L.), Division of Cardiology (J.L.S.), School of Biomedical Engineering (R.A.R.), Faculty of Medicine, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Robert A. Rose
- From the Department of Physiology and Biophysics (R.H., S.L.M., I.P., M.M., H.J.J., O.B., S.B.O., J.L.S., R.A.R.), IWK Health Centre (S.B.O.), Department of Surgery (S.B.O., J.-F.L.), Division of Cardiology (J.L.S.), School of Biomedical Engineering (R.A.R.), Faculty of Medicine, Dalhousie University, Halifax, Nova Scotia, Canada
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Harada M, Tadevosyan A, Qi X, Xiao J, Liu T, Voigt N, Karck M, Kamler M, Kodama I, Murohara T, Dobrev D, Nattel S. Atrial Fibrillation Activates AMP-Dependent Protein Kinase and its Regulation of Cellular Calcium Handling: Potential Role in Metabolic Adaptation and Prevention of Progression. J Am Coll Cardiol 2015; 66:47-58. [PMID: 26139058 DOI: 10.1016/j.jacc.2015.04.056] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/15/2014] [Revised: 04/05/2015] [Accepted: 04/23/2015] [Indexed: 11/28/2022]
Abstract
BACKGROUND Atrial fibrillation (AF) is associated with metabolic stress, which activates adenosine monophosphate-regulated protein kinase (AMPK). OBJECTIVES This study sought to examine AMPK response to AF and associated metabolic stress, along with consequences for atrial cardiomyocyte Ca(2+) handling. METHODS Calcium ion (Ca(2+)) transients (CaTs) and cell shortening (CS) were measured in dog and human atrial cardiomyocytes. AMPK phosphorylation and AMPK association with Ca(2+)-handling proteins were evaluated by immunoblotting and immunoprecipitation. RESULTS CaT amplitude and CS decreased at 4-min glycolysis inhibition (GI) but returned to baseline at 8 min, suggesting cellular adaptation to metabolic stress, potentially due to AMPK activation. GI increased AMPK-activating phosphorylation, and an AMPK inhibitor, compound C (CompC), abolished the adaptation of CaT and CS to GI. The AMPK activator 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR) increased CaT amplitude and CS, restoring CompC-induced CaT and CS decreases. CompC decreased L-type calcium channel current (ICa,L), along with ICa,L-triggered CaT amplitude and sarcoplasmic reticulum (SR) Ca(2+) content under voltage clamp conditions in dog cells and suppressed CaT and ICa,L in human cardiomyocytes. Small interfering ribonucleic acid-based AMPK knockdown decreased CaT amplitude in neonatal rat cardiomyocytes. L-type Ca(2+) channel α subunits coimmunoprecipitated with AMPKα. Atrial AMPK-activating phosphorylation was enhanced by 1 week of electrically maintained AF in dogs; fractional AMPK phosphorylation was increased in paroxysmal AF and reduced in longstanding persistent AF patients. CONCLUSIONS AMPK is activated by metabolic stress and AF, and helps maintain the intactness of atrial ICa,L, Ca(2+) handling, and cell contractility. AMPK contributes to the atrial compensatory response to AF-related metabolic stress; AF-related metabolic responses may be an interesting new therapeutic target.
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Affiliation(s)
- Masahide Harada
- Department of Medicine and Research Center, Montreal Heart Institute and Université de Montréal, Montreal, Quebec, Canada; Department of Cardiology, Fujita Health University School of Medicine, Toyoake, Japan
| | - Artavazd Tadevosyan
- Department of Medicine and Research Center, Montreal Heart Institute and Université de Montréal, Montreal, Quebec, Canada
| | - Xiaoyan Qi
- Department of Medicine and Research Center, Montreal Heart Institute and Université de Montréal, Montreal, Quebec, Canada
| | - Jiening Xiao
- Department of Medicine and Research Center, Montreal Heart Institute and Université de Montréal, Montreal, Quebec, Canada
| | - Tao Liu
- Department of Medicine and Research Center, Montreal Heart Institute and Université de Montréal, Montreal, Quebec, Canada; Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, China
| | - Niels Voigt
- Institute of Pharmacology, West German Cardiac and Vascular Center, School of Medicine, University Duisburg-Essen, Essen, Germany
| | - Matthias Karck
- Department of Cardiac Surgery, Heidelberg University, Heidelberg, Germany
| | - Markus Kamler
- Department of Cardiac Surgery, Huttrop Heart Center, Essen, Germany
| | | | - Toyoaki Murohara
- Department of Cardiology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Dobromir Dobrev
- Institute of Pharmacology, West German Cardiac and Vascular Center, School of Medicine, University Duisburg-Essen, Essen, Germany
| | - Stanley Nattel
- Department of Medicine and Research Center, Montreal Heart Institute and Université de Montréal, Montreal, Quebec, Canada.
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38
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Edwards JN, Blatter LA. Cardiac alternans and intracellular calcium cycling. Clin Exp Pharmacol Physiol 2015; 41:524-32. [PMID: 25040398 DOI: 10.1111/1440-1681.12231] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2013] [Revised: 03/12/2014] [Accepted: 03/17/2014] [Indexed: 12/20/2022]
Abstract
Cardiac alternans refers to a condition in which there is a periodic beat-to-beat oscillation in electrical activity and the strength of cardiac muscle contraction at a constant heart rate. Clinically, cardiac alternans occurs in settings that are typical for cardiac arrhythmias and has been causally linked to these conditions. At the cellular level, alternans is defined as beat-to-beat alternations in contraction amplitude (mechanical alternans), action potential duration (APD; electrical or APD alternans) and Ca(2+) transient amplitude (Ca(2+) alternans). The cause of alternans is multifactorial; however, alternans always originate from disturbances of the bidirectional coupling between membrane voltage (Vm ) and intracellular calcium ([Ca(2+) ]i ). Bidirectional coupling refers to the fact that, in cardiac cells, Vm depolarization and the generation of action potentials cause the elevation of [Ca(2+) ]i that is required for contraction (a process referred to as excitation-contraction coupling); conversely, changes of [Ca(2+) ]i control Vm because important membrane currents are Ca(2+) dependent. Evidence is mounting that alternans is ultimately caused by disturbances of cellular Ca(2+) signalling. Herein we review how two key factors of cardiac cellular Ca(2+) cycling, namely the release of Ca(2+) from internal stores and the capability of clearing the cytosol from Ca(2+) after each beat, determine the conditions under which alternans occurs. The contributions from key Ca(2+) -handling proteins (i.e. surface membrane channels, ion pumps and transporters and internal Ca(2+) release channels) are discussed.
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Affiliation(s)
- Joshua N Edwards
- Department of Molecular Biophysics and Physiology, Rush University Medical Center, Chicago, IL, USA
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39
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Ju YK, Lee BH, Trajanovska S, Hao G, Allen DG, Lei M, Cannell MB. The involvement of TRPC3 channels in sinoatrial arrhythmias. Front Physiol 2015; 6:86. [PMID: 25859221 PMCID: PMC4373262 DOI: 10.3389/fphys.2015.00086] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Accepted: 03/04/2015] [Indexed: 01/08/2023] Open
Abstract
Atrial fibrillation (AF) is a significant contributor to cardiovascular morbidity and mortality. The currently available treatments are limited and AF continues to be a major clinical challenge. Clinical studies have shown that AF is frequently associated with dysfunction in the sino-atrial node (SAN). The association between AF and SAN dysfunction is probably related to the communication between the SAN and the surrounding atrial cells that form the SAN-atrial pacemaker complex and/or pathological processes that affect both the SAN and atrial simultaneously. Recent evidence suggests that Ca2+ entry through TRPC3 (Transient Receptor Potential Canonical-3) channels may underlie several pathophysiological conditions -including cardiac arrhythmias. However, it is still not known if atrial and sinoatrial node cells are also involved. In this article we will first briefly review TRPC3 and IP3R signaling that relate to store/receptor-operated Ca2+ entry (SOCE/ROCE) mechanisms and cardiac arrhythmias. We will then present some of our recent research progress in this field. Our experiments results suggest that pacing-induced AF in angiotensin II (Ang II) treated mice are significantly reduced in mice lacking the TRPC3 gene (TRPC3−/− mice) compared to wild type controls. We also show that pacemaker cells express TRPC3 and several other molecular components related to SOCE/ROCE signaling, including STIM1 and IP3R. Activation of G-protein coupled receptors (GPCRs) signaling that is able to modulate SOCE/ROCE and Ang II induced Ca2+ homeostasis changes in sinoatrial complex being linked to TRPC3. The results provide new evidence that TRPC3 may play a role in sinoatrial and atrial arrhythmias that are caused by GPCRs activation.
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Affiliation(s)
- Yue-Kun Ju
- Department of Physiology, School of Medical Sciences, Bosch Institute, University of Sydney Sydney, NSW, Australia
| | - Bon Hyang Lee
- Department of Physiology, School of Medical Sciences, Bosch Institute, University of Sydney Sydney, NSW, Australia
| | - Sofie Trajanovska
- Department of Physiology, School of Medical Sciences, Bosch Institute, University of Sydney Sydney, NSW, Australia
| | - Gouliang Hao
- Department of Pharmacology, University of Oxford Oxford, UK
| | - David G Allen
- Department of Physiology, School of Medical Sciences, Bosch Institute, University of Sydney Sydney, NSW, Australia
| | - Ming Lei
- Department of Pharmacology, University of Oxford Oxford, UK
| | - Mark B Cannell
- Department of Physiology and Pharmacology, University of Bristol Bristol, UK
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40
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Pluteanu F, Heß J, Plackic J, Nikonova Y, Preisenberger J, Bukowska A, Schotten U, Rinne A, Kienitz MC, Schäfer MKH, Weihe E, Goette A, Kockskämper J. Early subcellular Ca2+ remodelling and increased propensity for Ca2+ alternans in left atrial myocytes from hypertensive rats. Cardiovasc Res 2015; 106:87-97. [PMID: 25691541 DOI: 10.1093/cvr/cvv045] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
AIMS Hypertension is a major risk factor for atrial fibrillation. We hypothesized that arterial hypertension would alter atrial myocyte calcium (Ca2+) handling and that these alterations would serve to trigger atrial tachyarrhythmias. METHODS AND RESULTS Left atria or left atrial (LA) myocytes were isolated from spontaneously hypertensive rats (SHR) or normotensive Wistar-Kyoto (WKY) controls. Early after the onset of hypertension, at 3 months of age, there were no differences in Ca2+ transients (CaTs) or expression and phosphorylation of Ca2+ handling proteins between SHR and WKY. At 7 months of age, when left ventricular (LV) hypertrophy had progressed and markers of fibrosis were increased in left atrium, CaTs (at 1 Hz stimulation) were still unchanged. Subcellular alterations in Ca2+ handling were observed, however, in SHR atrial myocytes including (i) reduced expression of the α1C subunit of and reduced Ca2+ influx through L-type Ca2+ channels, (ii) reduced expression of ryanodine receptors with increased phosphorylation at Ser2808, (iii) decreased activity of the Na+ / Ca2+ exchanger (at unaltered intracellular Na+ concentration), and (iv) increased SR Ca2+ load with reduced fractional release. These changes were associated with an increased propensity of SHR atrial myocytes to develop frequency-dependent, arrhythmogenic Ca2+ alternans. CONCLUSIONS In SHR, hypertension induces early subcellular LA myocyte Ca2+ remodelling during compensated LV hypertrophy. In basal conditions, atrial myocyte CaTs are not changed. At increased stimulation frequency, however, SHR atrial myocytes become more prone to arrhythmogenic Ca2+ alternans, suggesting a link between hypertension, atrial Ca2+ homeostasis, and development of atrial tachyarrhythmias.
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Affiliation(s)
- Florentina Pluteanu
- Institute of Pharmacology and Clinical Pharmacy, Biochemical and Pharmacological Center (BPC) Marburg, Philipps-University Marburg, Karl-von-Frisch-Str. 1, 35032 Marburg, Germany
| | - Johannes Heß
- Institute of Pharmacology and Clinical Pharmacy, Biochemical and Pharmacological Center (BPC) Marburg, Philipps-University Marburg, Karl-von-Frisch-Str. 1, 35032 Marburg, Germany
| | - Jelena Plackic
- Institute of Pharmacology and Clinical Pharmacy, Biochemical and Pharmacological Center (BPC) Marburg, Philipps-University Marburg, Karl-von-Frisch-Str. 1, 35032 Marburg, Germany
| | - Yulia Nikonova
- Institute of Pharmacology and Clinical Pharmacy, Biochemical and Pharmacological Center (BPC) Marburg, Philipps-University Marburg, Karl-von-Frisch-Str. 1, 35032 Marburg, Germany
| | - Judit Preisenberger
- Institute of Pharmacology and Clinical Pharmacy, Biochemical and Pharmacological Center (BPC) Marburg, Philipps-University Marburg, Karl-von-Frisch-Str. 1, 35032 Marburg, Germany
| | - Alicja Bukowska
- Working Group of Molecular Electrophysiology, Medical Faculty, Otto-von-Guericke-University Magdeburg, Magdeburg, Germany
| | - Ulrich Schotten
- Department of Physiology, Cardiovascular Research Institute Maastricht, University Maastricht, Maastricht, The Netherlands
| | - Andreas Rinne
- Institute of Physiology, Ruhr-University Bochum, Bochum, Germany
| | | | - Martin K-H Schäfer
- Institute of Anatomy and Cell Biology, Philipps-University Marburg, Marburg, Germany
| | - Eberhard Weihe
- Institute of Anatomy and Cell Biology, Philipps-University Marburg, Marburg, Germany
| | - Andreas Goette
- Working Group of Molecular Electrophysiology, Medical Faculty, Otto-von-Guericke-University Magdeburg, Magdeburg, Germany St. Vincenz-Hospital, Paderborn, Germany
| | - Jens Kockskämper
- Institute of Pharmacology and Clinical Pharmacy, Biochemical and Pharmacological Center (BPC) Marburg, Philipps-University Marburg, Karl-von-Frisch-Str. 1, 35032 Marburg, Germany
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41
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Shimizu H, Schredelseker J, Huang J, Lu K, Naghdi S, Lu F, Franklin S, Fiji HD, Wang K, Zhu H, Tian C, Lin B, Nakano H, Ehrlich A, Nakai J, Stieg AZ, Gimzewski JK, Nakano A, Goldhaber JI, Vondriska TM, Hajnóczky G, Kwon O, Chen JN. Mitochondrial Ca(2+) uptake by the voltage-dependent anion channel 2 regulates cardiac rhythmicity. eLife 2015; 4. [PMID: 25588501 PMCID: PMC4293673 DOI: 10.7554/elife.04801] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2014] [Accepted: 12/23/2014] [Indexed: 01/02/2023] Open
Abstract
Tightly regulated Ca2+ homeostasis is a prerequisite for proper cardiac function. To dissect the regulatory network of cardiac Ca2+ handling, we performed a chemical suppressor screen on zebrafish tremblor embryos, which suffer from Ca2+ extrusion defects. Efsevin was identified based on its potent activity to restore coordinated contractions in tremblor. We show that efsevin binds to VDAC2, potentiates mitochondrial Ca2+ uptake and accelerates the transfer of Ca2+ from intracellular stores into mitochondria. In cardiomyocytes, efsevin restricts the temporal and spatial boundaries of Ca2+ sparks and thereby inhibits Ca2+ overload-induced erratic Ca2+ waves and irregular contractions. We further show that overexpression of VDAC2 recapitulates the suppressive effect of efsevin on tremblor embryos whereas VDAC2 deficiency attenuates efsevin's rescue effect and that VDAC2 functions synergistically with MCU to suppress cardiac fibrillation in tremblor. Together, these findings demonstrate a critical modulatory role for VDAC2-dependent mitochondrial Ca2+ uptake in the regulation of cardiac rhythmicity. DOI:http://dx.doi.org/10.7554/eLife.04801.001 The heart is a large muscle that pumps blood around the body by maintaining a regular rhythm of contraction and relaxation. If the heart loses this regular rhythm it works less efficiently, which can lead to life-threatening conditions. Regular heart rhythms are maintained by changes in the concentration of calcium ions in the cytoplasm of the heart muscle cells. These changes are synchronised so that the heart cells contract in a controlled manner. In each cell, a contraction begins when calcium ions from outside the cell enter the cytoplasm by passing through a channel protein in the membrane that surrounds the cell. This triggers the release of even more calcium ions into the cytoplasm from stores within the cell. For the cells to relax, the calcium ions must then be pumped out of the cytoplasm to lower the calcium ion concentration back to the original level. Shimizu et al. studied a zebrafish mutant—called tremblor—that has irregular heart rhythms because its heart muscle cells are unable to efficiently remove calcium ions from the cytoplasm. Embryos of the tremblor mutant were treated with a wide variety of chemical compounds with the aim of finding some that could correct the heart defect. A compound called efsevin restores regular heart rhythms in tremblor mutants. Efsevin binds to a pump protein called VDAC2, which is found in compartments called mitochondria within the cell. Although mitochondria are best known for their role in supplying energy for the cell, they also act as internal stores for calcium. By binding to VDAC2, efsevin increases the rate at which calcium ions are pumped from the cytoplasm into the mitochondria. This restores rhythmic calcium ion cycling in the cytoplasm and enables the heart muscle cells to develop regular rhythms of contraction and relaxation. Increasing the levels of VDAC2 or another similar calcium ion pump protein in the heart cells can also restore a regular heart rhythm. Efsevin can also correct irregular heart rhythms in human and mouse heart muscle cells, therefore the new role for mitochondria in controlling heart rhythms found by Shimizu et al. appears to be shared in other animals. The experiments have also identified the VDAC family of proteins as potential new targets for drug therapies to treat people with irregular heart rhythms. DOI:http://dx.doi.org/10.7554/eLife.04801.002
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Affiliation(s)
- Hirohito Shimizu
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, Los Angeles, United States
| | - Johann Schredelseker
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, Los Angeles, United States
| | - Jie Huang
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, Los Angeles, United States
| | - Kui Lu
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, United States
| | - Shamim Naghdi
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, United States
| | - Fei Lu
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, Los Angeles, United States
| | - Sarah Franklin
- Department of Anesthesiology, University of California, Los Angeles, Los Angeles, United States
| | - Hannah Dg Fiji
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, United States
| | - Kevin Wang
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, Los Angeles, United States
| | - Huanqi Zhu
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, United States
| | - Cheng Tian
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, Los Angeles, United States
| | - Billy Lin
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, Los Angeles, United States
| | - Haruko Nakano
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, Los Angeles, United States
| | - Amy Ehrlich
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, United States
| | - Junichi Nakai
- Brain Science Institute, Saitama University, Saitama, Japan
| | - Adam Z Stieg
- California NanoSystems Institute, University of California, Los Angeles, Los Angeles, United States
| | - James K Gimzewski
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, United States
| | - Atsushi Nakano
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, Los Angeles, United States
| | | | - Thomas M Vondriska
- Department of Anesthesiology, University of California, Los Angeles, Los Angeles, United States
| | - György Hajnóczky
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, United States
| | - Ohyun Kwon
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, United States
| | - Jau-Nian Chen
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, Los Angeles, United States
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Greiser M, Kerfant BG, Williams GS, Voigt N, Harks E, Dibb KM, Giese A, Meszaros J, Verheule S, Ravens U, Allessie MA, Gammie JS, van der Velden J, Lederer WJ, Dobrev D, Schotten U. Tachycardia-induced silencing of subcellular Ca2+ signaling in atrial myocytes. J Clin Invest 2014; 124:4759-72. [PMID: 25329692 PMCID: PMC4347234 DOI: 10.1172/jci70102] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2013] [Accepted: 08/28/2014] [Indexed: 01/06/2023] Open
Abstract
Atrial fibrillation (AF) is characterized by sustained high atrial activation rates and arrhythmogenic cellular Ca2+ signaling instability; however, it is not clear how a high atrial rate and Ca2+ instability may be related. Here, we characterized subcellular Ca2+ signaling after 5 days of high atrial rates in a rabbit model. While some changes were similar to those in persistent AF, we identified a distinct pattern of stabilized subcellular Ca2+ signaling. Ca2+ sparks, arrhythmogenic Ca2+ waves, sarcoplasmic reticulum (SR) Ca2+ leak, and SR Ca2+ content were largely unaltered. Based on computational analysis, these findings were consistent with a higher Ca2+ leak due to PKA-dependent phosphorylation of SR Ca2+ channels (RyR2s), fewer RyR2s, and smaller RyR2 clusters in the SR. We determined that less Ca2+ release per [Ca2+]i transient, increased Ca2+ buffering strength, shortened action potentials, and reduced L-type Ca2+ current contribute to a stunning reduction of intracellular Na+ concentration following rapid atrial pacing. In both patients with AF and in our rabbit model, this silencing led to failed propagation of the [Ca2+]i signal to the myocyte center. We conclude that sustained high atrial rates alone silence Ca2+ signaling and do not produce Ca2+ signaling instability, consistent with an adaptive molecular and cellular response to atrial tachycardia.
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Affiliation(s)
- Maura Greiser
- Department of Physiology, Maastricht University, Maastricht, the Netherlands. Center for Biomedical Engineering and Technology, Laboratory of Molecular Cardiology, and Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland, USA. Institute of Pharmacology, Faculty of Medicine, University Duisburg-Essen, Essen, Germany. Unit of Cardiac Physiology, Manchester Academic Health Sciences Centre, Manchester, United Kingdom. Department of Pharmacology and Toxicology, Dresden University of Technology, Dresden, Germany. Division of Cardiac Surgery, University of Maryland Medical Center, Baltimore, Maryland, USA. Laboratory for Physiology, VU University Medical Center, Amsterdam, the Netherlands
| | - Benoît-Gilles Kerfant
- Department of Physiology, Maastricht University, Maastricht, the Netherlands. Center for Biomedical Engineering and Technology, Laboratory of Molecular Cardiology, and Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland, USA. Institute of Pharmacology, Faculty of Medicine, University Duisburg-Essen, Essen, Germany. Unit of Cardiac Physiology, Manchester Academic Health Sciences Centre, Manchester, United Kingdom. Department of Pharmacology and Toxicology, Dresden University of Technology, Dresden, Germany. Division of Cardiac Surgery, University of Maryland Medical Center, Baltimore, Maryland, USA. Laboratory for Physiology, VU University Medical Center, Amsterdam, the Netherlands
| | - George S.B. Williams
- Department of Physiology, Maastricht University, Maastricht, the Netherlands. Center for Biomedical Engineering and Technology, Laboratory of Molecular Cardiology, and Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland, USA. Institute of Pharmacology, Faculty of Medicine, University Duisburg-Essen, Essen, Germany. Unit of Cardiac Physiology, Manchester Academic Health Sciences Centre, Manchester, United Kingdom. Department of Pharmacology and Toxicology, Dresden University of Technology, Dresden, Germany. Division of Cardiac Surgery, University of Maryland Medical Center, Baltimore, Maryland, USA. Laboratory for Physiology, VU University Medical Center, Amsterdam, the Netherlands
| | - Niels Voigt
- Department of Physiology, Maastricht University, Maastricht, the Netherlands. Center for Biomedical Engineering and Technology, Laboratory of Molecular Cardiology, and Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland, USA. Institute of Pharmacology, Faculty of Medicine, University Duisburg-Essen, Essen, Germany. Unit of Cardiac Physiology, Manchester Academic Health Sciences Centre, Manchester, United Kingdom. Department of Pharmacology and Toxicology, Dresden University of Technology, Dresden, Germany. Division of Cardiac Surgery, University of Maryland Medical Center, Baltimore, Maryland, USA. Laboratory for Physiology, VU University Medical Center, Amsterdam, the Netherlands
| | - Erik Harks
- Department of Physiology, Maastricht University, Maastricht, the Netherlands. Center for Biomedical Engineering and Technology, Laboratory of Molecular Cardiology, and Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland, USA. Institute of Pharmacology, Faculty of Medicine, University Duisburg-Essen, Essen, Germany. Unit of Cardiac Physiology, Manchester Academic Health Sciences Centre, Manchester, United Kingdom. Department of Pharmacology and Toxicology, Dresden University of Technology, Dresden, Germany. Division of Cardiac Surgery, University of Maryland Medical Center, Baltimore, Maryland, USA. Laboratory for Physiology, VU University Medical Center, Amsterdam, the Netherlands
| | - Katharine M. Dibb
- Department of Physiology, Maastricht University, Maastricht, the Netherlands. Center for Biomedical Engineering and Technology, Laboratory of Molecular Cardiology, and Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland, USA. Institute of Pharmacology, Faculty of Medicine, University Duisburg-Essen, Essen, Germany. Unit of Cardiac Physiology, Manchester Academic Health Sciences Centre, Manchester, United Kingdom. Department of Pharmacology and Toxicology, Dresden University of Technology, Dresden, Germany. Division of Cardiac Surgery, University of Maryland Medical Center, Baltimore, Maryland, USA. Laboratory for Physiology, VU University Medical Center, Amsterdam, the Netherlands
| | - Anne Giese
- Department of Physiology, Maastricht University, Maastricht, the Netherlands. Center for Biomedical Engineering and Technology, Laboratory of Molecular Cardiology, and Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland, USA. Institute of Pharmacology, Faculty of Medicine, University Duisburg-Essen, Essen, Germany. Unit of Cardiac Physiology, Manchester Academic Health Sciences Centre, Manchester, United Kingdom. Department of Pharmacology and Toxicology, Dresden University of Technology, Dresden, Germany. Division of Cardiac Surgery, University of Maryland Medical Center, Baltimore, Maryland, USA. Laboratory for Physiology, VU University Medical Center, Amsterdam, the Netherlands
| | - Janos Meszaros
- Department of Physiology, Maastricht University, Maastricht, the Netherlands. Center for Biomedical Engineering and Technology, Laboratory of Molecular Cardiology, and Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland, USA. Institute of Pharmacology, Faculty of Medicine, University Duisburg-Essen, Essen, Germany. Unit of Cardiac Physiology, Manchester Academic Health Sciences Centre, Manchester, United Kingdom. Department of Pharmacology and Toxicology, Dresden University of Technology, Dresden, Germany. Division of Cardiac Surgery, University of Maryland Medical Center, Baltimore, Maryland, USA. Laboratory for Physiology, VU University Medical Center, Amsterdam, the Netherlands
| | - Sander Verheule
- Department of Physiology, Maastricht University, Maastricht, the Netherlands. Center for Biomedical Engineering and Technology, Laboratory of Molecular Cardiology, and Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland, USA. Institute of Pharmacology, Faculty of Medicine, University Duisburg-Essen, Essen, Germany. Unit of Cardiac Physiology, Manchester Academic Health Sciences Centre, Manchester, United Kingdom. Department of Pharmacology and Toxicology, Dresden University of Technology, Dresden, Germany. Division of Cardiac Surgery, University of Maryland Medical Center, Baltimore, Maryland, USA. Laboratory for Physiology, VU University Medical Center, Amsterdam, the Netherlands
| | - Ursula Ravens
- Department of Physiology, Maastricht University, Maastricht, the Netherlands. Center for Biomedical Engineering and Technology, Laboratory of Molecular Cardiology, and Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland, USA. Institute of Pharmacology, Faculty of Medicine, University Duisburg-Essen, Essen, Germany. Unit of Cardiac Physiology, Manchester Academic Health Sciences Centre, Manchester, United Kingdom. Department of Pharmacology and Toxicology, Dresden University of Technology, Dresden, Germany. Division of Cardiac Surgery, University of Maryland Medical Center, Baltimore, Maryland, USA. Laboratory for Physiology, VU University Medical Center, Amsterdam, the Netherlands
| | - Maurits A. Allessie
- Department of Physiology, Maastricht University, Maastricht, the Netherlands. Center for Biomedical Engineering and Technology, Laboratory of Molecular Cardiology, and Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland, USA. Institute of Pharmacology, Faculty of Medicine, University Duisburg-Essen, Essen, Germany. Unit of Cardiac Physiology, Manchester Academic Health Sciences Centre, Manchester, United Kingdom. Department of Pharmacology and Toxicology, Dresden University of Technology, Dresden, Germany. Division of Cardiac Surgery, University of Maryland Medical Center, Baltimore, Maryland, USA. Laboratory for Physiology, VU University Medical Center, Amsterdam, the Netherlands
| | - James S. Gammie
- Department of Physiology, Maastricht University, Maastricht, the Netherlands. Center for Biomedical Engineering and Technology, Laboratory of Molecular Cardiology, and Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland, USA. Institute of Pharmacology, Faculty of Medicine, University Duisburg-Essen, Essen, Germany. Unit of Cardiac Physiology, Manchester Academic Health Sciences Centre, Manchester, United Kingdom. Department of Pharmacology and Toxicology, Dresden University of Technology, Dresden, Germany. Division of Cardiac Surgery, University of Maryland Medical Center, Baltimore, Maryland, USA. Laboratory for Physiology, VU University Medical Center, Amsterdam, the Netherlands
| | - Jolanda van der Velden
- Department of Physiology, Maastricht University, Maastricht, the Netherlands. Center for Biomedical Engineering and Technology, Laboratory of Molecular Cardiology, and Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland, USA. Institute of Pharmacology, Faculty of Medicine, University Duisburg-Essen, Essen, Germany. Unit of Cardiac Physiology, Manchester Academic Health Sciences Centre, Manchester, United Kingdom. Department of Pharmacology and Toxicology, Dresden University of Technology, Dresden, Germany. Division of Cardiac Surgery, University of Maryland Medical Center, Baltimore, Maryland, USA. Laboratory for Physiology, VU University Medical Center, Amsterdam, the Netherlands
| | - W. Jonathan Lederer
- Department of Physiology, Maastricht University, Maastricht, the Netherlands. Center for Biomedical Engineering and Technology, Laboratory of Molecular Cardiology, and Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland, USA. Institute of Pharmacology, Faculty of Medicine, University Duisburg-Essen, Essen, Germany. Unit of Cardiac Physiology, Manchester Academic Health Sciences Centre, Manchester, United Kingdom. Department of Pharmacology and Toxicology, Dresden University of Technology, Dresden, Germany. Division of Cardiac Surgery, University of Maryland Medical Center, Baltimore, Maryland, USA. Laboratory for Physiology, VU University Medical Center, Amsterdam, the Netherlands
| | - Dobromir Dobrev
- Department of Physiology, Maastricht University, Maastricht, the Netherlands. Center for Biomedical Engineering and Technology, Laboratory of Molecular Cardiology, and Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland, USA. Institute of Pharmacology, Faculty of Medicine, University Duisburg-Essen, Essen, Germany. Unit of Cardiac Physiology, Manchester Academic Health Sciences Centre, Manchester, United Kingdom. Department of Pharmacology and Toxicology, Dresden University of Technology, Dresden, Germany. Division of Cardiac Surgery, University of Maryland Medical Center, Baltimore, Maryland, USA. Laboratory for Physiology, VU University Medical Center, Amsterdam, the Netherlands
| | - Ulrich Schotten
- Department of Physiology, Maastricht University, Maastricht, the Netherlands. Center for Biomedical Engineering and Technology, Laboratory of Molecular Cardiology, and Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland, USA. Institute of Pharmacology, Faculty of Medicine, University Duisburg-Essen, Essen, Germany. Unit of Cardiac Physiology, Manchester Academic Health Sciences Centre, Manchester, United Kingdom. Department of Pharmacology and Toxicology, Dresden University of Technology, Dresden, Germany. Division of Cardiac Surgery, University of Maryland Medical Center, Baltimore, Maryland, USA. Laboratory for Physiology, VU University Medical Center, Amsterdam, the Netherlands
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Caldwell JL, Smith CER, Taylor RF, Kitmitto A, Eisner DA, Dibb KM, Trafford AW. Dependence of cardiac transverse tubules on the BAR domain protein amphiphysin II (BIN-1). Circ Res 2014; 115:986-96. [PMID: 25332206 DOI: 10.1161/circresaha.116.303448] [Citation(s) in RCA: 96] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
RATIONALE Transverse tubules (t-tubules) regulate cardiac excitation-contraction coupling and exhibit interchamber and interspecies differences in expression. In cardiac disease, t-tubule loss occurs and affects the systolic calcium transient. However, the mechanisms controlling t-tubule maintenance and whether these factors differ between species, cardiac chambers, and in a disease setting remain unclear. OBJECTIVE To determine the role of the Bin/Amphiphysin/Rvs domain protein amphiphysin II (AmpII) in regulating t-tubule maintenance and the systolic calcium transient. METHODS AND RESULTS T-tubule density was assessed by di-4-ANEPPS, FM4-64 or WGA staining using confocal microscopy. In rat, ferret, and sheep hearts t-tubule density and AmpII protein levels were lower in the atrium than in the ventricle. Heart failure (HF) was induced in sheep using right ventricular tachypacing and ferrets by ascending aortic coarctation. In both HF models, AmpII protein and t-tubule density were decreased in the ventricles. In the sheep, atrial t-tubules were also lost in HF and AmpII levels decreased. Conversely, junctophilin 2 levels did not show interchamber differences in the rat and ferret nor did they change in HF in the sheep or ferret. In addition, in rat atrial and sheep HF atrial cells where t-tubules were absent, junctophilin 2 had sarcomeric intracellular distribution. Small interfering RNA-induced knockdown of AmpII protein reduced t-tubule density, calcium transient amplitude, and the synchrony of the systolic calcium transient. CONCLUSIONS AmpII is intricately involved in t-tubule maintenance. Reducing AmpII protein decreases t-tubule density, reduces the amplitude, and increases the heterogeneity of the systolic calcium transient.
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Affiliation(s)
- Jessica L Caldwell
- From the Unit of Cardiac Physiology and Cardiac Biophysics Group, Institute of Cardiovascular Sciences, Manchester Academic Health Science Centre, University of Manchester, Manchester, United Kingdom
| | - Charlotte E R Smith
- From the Unit of Cardiac Physiology and Cardiac Biophysics Group, Institute of Cardiovascular Sciences, Manchester Academic Health Science Centre, University of Manchester, Manchester, United Kingdom
| | - Rebecca F Taylor
- From the Unit of Cardiac Physiology and Cardiac Biophysics Group, Institute of Cardiovascular Sciences, Manchester Academic Health Science Centre, University of Manchester, Manchester, United Kingdom
| | - Ashraf Kitmitto
- From the Unit of Cardiac Physiology and Cardiac Biophysics Group, Institute of Cardiovascular Sciences, Manchester Academic Health Science Centre, University of Manchester, Manchester, United Kingdom
| | - David A Eisner
- From the Unit of Cardiac Physiology and Cardiac Biophysics Group, Institute of Cardiovascular Sciences, Manchester Academic Health Science Centre, University of Manchester, Manchester, United Kingdom
| | - Katharine M Dibb
- From the Unit of Cardiac Physiology and Cardiac Biophysics Group, Institute of Cardiovascular Sciences, Manchester Academic Health Science Centre, University of Manchester, Manchester, United Kingdom
| | - Andrew W Trafford
- From the Unit of Cardiac Physiology and Cardiac Biophysics Group, Institute of Cardiovascular Sciences, Manchester Academic Health Science Centre, University of Manchester, Manchester, United Kingdom.
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44
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KCNE2 modulates cardiac L-type Ca2+ channel. J Mol Cell Cardiol 2014; 72:208-18. [DOI: 10.1016/j.yjmcc.2014.03.013] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2013] [Revised: 03/05/2014] [Accepted: 03/18/2014] [Indexed: 11/19/2022]
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Koivumäki JT, Seemann G, Maleckar MM, Tavi P. In silico screening of the key cellular remodeling targets in chronic atrial fibrillation. PLoS Comput Biol 2014; 10:e1003620. [PMID: 24853123 PMCID: PMC4031057 DOI: 10.1371/journal.pcbi.1003620] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Accepted: 03/30/2014] [Indexed: 02/07/2023] Open
Abstract
Chronic atrial fibrillation (AF) is a complex disease with underlying changes in electrophysiology, calcium signaling and the structure of atrial myocytes. How these individual remodeling targets and their emergent interactions contribute to cell physiology in chronic AF is not well understood. To approach this problem, we performed in silico experiments in a computational model of the human atrial myocyte. The remodeled function of cellular components was based on a broad literature review of in vitro findings in chronic AF, and these were integrated into the model to define a cohort of virtual cells. Simulation results indicate that while the altered function of calcium and potassium ion channels alone causes a pronounced decrease in action potential duration, remodeling of intracellular calcium handling also has a substantial impact on the chronic AF phenotype. We additionally found that the reduction in amplitude of the calcium transient in chronic AF as compared to normal sinus rhythm is primarily due to the remodeling of calcium channel function, calcium handling and cellular geometry. Finally, we found that decreased electrical resistance of the membrane together with remodeled calcium handling synergistically decreased cellular excitability and the subsequent inducibility of repolarization abnormalities in the human atrial myocyte in chronic AF. We conclude that the presented results highlight the complexity of both intrinsic cellular interactions and emergent properties of human atrial myocytes in chronic AF. Therefore, reversing remodeling for a single remodeled component does little to restore the normal sinus rhythm phenotype. These findings may have important implications for developing novel therapeutic approaches for chronic AF.
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Affiliation(s)
- Jussi T. Koivumäki
- Simula Research Laboratory, Center for Cardiological Innovation and Center for Biomedical Computing, Oslo, Norway
- Department of Biotechnology and Molecular Medicine, A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland
| | - Gunnar Seemann
- Institute of Biomedical Engineering, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Mary M. Maleckar
- Simula Research Laboratory, Center for Cardiological Innovation and Center for Biomedical Computing, Oslo, Norway
| | - Pasi Tavi
- Department of Biotechnology and Molecular Medicine, A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland
- * E-mail:
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46
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Okumura S, Fujita T, Cai W, Jin M, Namekata I, Mototani Y, Jin H, Ohnuki Y, Tsuneoka Y, Kurotani R, Suita K, Kawakami Y, Hamaguchi S, Abe T, Kiyonari H, Tsunematsu T, Bai Y, Suzuki S, Hidaka Y, Umemura M, Ichikawa Y, Yokoyama U, Sato M, Ishikawa F, Izumi-Nakaseko H, Adachi-Akahane S, Tanaka H, Ishikawa Y. Epac1-dependent phospholamban phosphorylation mediates the cardiac response to stresses. J Clin Invest 2014; 124:2785-801. [PMID: 24892712 DOI: 10.1172/jci64784] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
PKA phosphorylates multiple molecules involved in calcium (Ca2+) handling in cardiac myocytes and is considered to be the predominant regulator of β-adrenergic receptor-mediated enhancement of cardiac contractility; however, recent identification of exchange protein activated by cAMP (EPAC), which is independently activated by cAMP, has challenged this paradigm. Mice lacking Epac1 (Epac1 KO) exhibited decreased cardiac contractility with reduced phospholamban (PLN) phosphorylation at serine-16, the major PKA-mediated phosphorylation site. In Epac1 KO mice, intracellular Ca2+ storage and the magnitude of Ca2+ movement were decreased; however, PKA expression remained unchanged, and activation of PKA with isoproterenol improved cardiac contractility. In contrast, direct activation of EPAC in cardiomyocytes led to increased PLN phosphorylation at serine-16, which was dependent on PLC and PKCε. Importantly, Epac1 deletion protected the heart from various stresses, while Epac2 deletion was not protective. Compared with WT mice, aortic banding induced a similar degree of cardiac hypertrophy in Epac1 KO; however, lack of Epac1 prevented subsequent cardiac dysfunction as a result of decreased cardiac myocyte apoptosis and fibrosis. Similarly, Epac1 KO animals showed resistance to isoproterenol- and aging-induced cardiomyopathy and attenuation of arrhythmogenic activity. These data support Epac1 as an important regulator of PKA-independent PLN phosphorylation and indicate that Epac1 regulates cardiac responsiveness to various stresses.
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Pinho-Gomes AC, Reilly S, Brandes RP, Casadei B. Targeting inflammation and oxidative stress in atrial fibrillation: role of 3-hydroxy-3-methylglutaryl-coenzyme a reductase inhibition with statins. Antioxid Redox Signal 2014; 20:1268-85. [PMID: 23924190 PMCID: PMC3934546 DOI: 10.1089/ars.2013.5542] [Citation(s) in RCA: 74] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
SIGNIFICANCE Atrial fibrillation (AF) is a burgeoning health-care problem, and the currently available therapeutic armamentarium is barely efficient. Experimental and clinical evidence implicates inflammation and myocardial oxidative stress in the pathogenesis of AF. RECENT ADVANCES Local and systemic inflammation has been found to both precede and follow the new onset of AF, and NOX2-dependent generation of reactive oxygen species in human right atrial samples has been independently associated with the occurrence of AF in the postoperative period in patients undergoing cardiac surgery. Anti-inflammatory and antioxidant agents can prevent atrial electrical remodeling in animal models of atrial tachypacing and the new onset of AF after cardiac surgery, suggesting a causal relationship between inflammation/oxidative stress and the atrial substrate that supports AF. CRITICAL ISSUES Statin therapy, by redressing the myocardial nitroso-redox balance and reducing inflammation, has emerged as a potentially effective strategy for the prevention of AF. Evidence indicates that statins prevent AF-induced electrical remodeling in animal models of atrial tachypacing and may reduce the new onset of AF after cardiac surgery. However, whether statins have antiarrhythmic properties in humans has yet to be conclusively demonstrated, as data from randomized controlled trials specifically addressing the relevance of statin therapy for the primary and secondary prevention of AF remain scanty. FUTURE DIRECTIONS A better understanding of the mechanisms underpinning the putative antiarrhythmic effects of statins may afford tailoring AF treatment to specific clinical settings and patient's subgroups. Large-scale randomized clinical trials are needed to support the indication of statin therapy solely on the basis of AF prevention.
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Affiliation(s)
- Ana Catarina Pinho-Gomes
- 1 Department of Cardiovascular Medicine, University of Oxford , John Radcliffe Hospital, Oxford, United Kingdom
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Banerjee A, Taillandier S, Olesen JB, Lane DA, Lallemand B, Lip GY, Fauchier L. Ejection fraction and outcomes in patients with atrial fibrillation and heart failure: the Loire Valley Atrial Fibrillation Project. Eur J Heart Fail 2014; 14:295-301. [PMID: 22294759 DOI: 10.1093/eurjhf/hfs005] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Affiliation(s)
- Amitava Banerjee
- University of Birmingham Centre for Cardiovascular Sciences; City Hospital; Birmingham B18 7QH UK
| | - Sophie Taillandier
- Service de Cardiologie, Pôle Coeur Thorax Vasculaire, Centre Hospitalier, Universitaire Trousseau et Faculté de Médecine; Université François Rabelais; Tours France
| | - Jonas Bjerring Olesen
- University of Birmingham Centre for Cardiovascular Sciences; City Hospital; Birmingham B18 7QH UK
- Department of Cardiology; Copenhagen University Hospital Gentofte; Hellerup 2900 Denmark
| | - Deirdre A. Lane
- University of Birmingham Centre for Cardiovascular Sciences; City Hospital; Birmingham B18 7QH UK
| | - Benedicte Lallemand
- Service de Cardiologie, Pôle Coeur Thorax Vasculaire, Centre Hospitalier, Universitaire Trousseau et Faculté de Médecine; Université François Rabelais; Tours France
| | - Gregory Y.H. Lip
- University of Birmingham Centre for Cardiovascular Sciences; City Hospital; Birmingham B18 7QH UK
| | - Laurent Fauchier
- Service de Cardiologie, Pôle Coeur Thorax Vasculaire, Centre Hospitalier, Universitaire Trousseau et Faculté de Médecine; Université François Rabelais; Tours France
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Faggioni M, Savio-Galimberti E, Venkataraman R, Hwang HS, Kannankeril PJ, Darbar D, Knollmann BC. Suppression of spontaneous ca elevations prevents atrial fibrillation in calsequestrin 2-null hearts. Circ Arrhythm Electrophysiol 2014; 7:313-20. [PMID: 24493699 DOI: 10.1161/circep.113.000994] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
BACKGROUND Atrial fibrillation (AF) risk has been associated with leaky ryanodine receptor 2 (RyR2) Ca release channels. Patients with mutations in RyR2 or in the sarcoplasmic reticulum Ca-binding protein calsequestrin 2 (Casq2) display an increased risk for AF. Here, we examine the underlying mechanisms of AF associated with loss of Casq2 and test mechanism-based drug therapy. METHODS AND RESULTS Compared with wild-type Casq2+/+ mice, atrial burst pacing consistently induced atrial flutter or AF in Casq2-/- mice and in isolated Casq2-/- hearts. Atrial optical voltage maps obtained from isolated hearts revealed multiple independent activation sites arising predominantly from the pulmonary vein region. Ca and voltage mapping demonstrated diastolic subthreshold spontaneous Ca elevations (SCaEs) and delayed afterdepolarizations whenever the pacing train failed to induce AF. The dual RyR2 and Na channel inhibitor R-propafenone (3 μmol/L) significantly reduced frequency and amplitude of SCaEs and delayed afterdepolarizations in atrial myocytes and intact atria and prevented induction of AF. In contrast, the S-enantiomer of propafenone, an equipotent Na channel blocker but much weaker RyR2 inhibitor, did not reduce SCaEs and delayed afterdepolarizations and failed to prevent AF. CONCLUSIONS Loss of Casq2 increases risk of AF by promoting regional SCaEs and delayed afterdepolarizations in atrial tissue, which can be prevented by RyR2 inhibition with R-propafenone. Targeting AF caused by leaky RyR2 Ca channels with R-propafenone may be a more mechanism-based approach to treating this common arrhythmia.
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Affiliation(s)
- Michela Faggioni
- Division of Clinical Pharmacology, Department of Medicine, Division of Cardiology, Department of Medicine, Department of Biomedical Engineering and Physics, and Division of Cardiology, Department of Pediatrics, Vanderbilt University, Nashville, TN; and Department of Cardiovascular Diseases, University of Pisa, Pisa, Italy
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50
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Khananshvili D. Sodium-calcium exchangers (NCX): molecular hallmarks underlying the tissue-specific and systemic functions. Pflugers Arch 2013; 466:43-60. [PMID: 24281864 DOI: 10.1007/s00424-013-1405-y] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2013] [Revised: 11/06/2013] [Accepted: 11/09/2013] [Indexed: 12/19/2022]
Abstract
NCX proteins explore the electrochemical gradient of Na(+) to mediate Ca(2+)-fluxes in exchange with Na(+) either in the Ca(2+)-efflux (forward) or Ca(2+)-influx (reverse) mode, whereas the directionality depends on ionic concentrations and membrane potential. Mammalian NCX variants (NCX1-3) and their splice variants are expressed in a tissue-specific manner to modulate the heartbeat rate and contractile force, the brain's long-term potentiation and learning, blood pressure, renal Ca(2+) reabsorption, the immune response, neurotransmitter and insulin secretion, apoptosis and proliferation, mitochondrial bioenergetics, etc. Although the forward mode of NCX represents a major physiological module, a transient reversal of NCX may contribute to EC-coupling, vascular constriction, and synaptic transmission. Notably, the reverse mode of NCX becomes predominant in pathological settings. Since the expression levels of NCX variants are disease-related, the selective pharmacological targeting of tissue-specific NCX variants could be beneficial, thereby representing a challenge. Recent structural and biophysical studies revealed a common module for decoding the Ca(2+)-induced allosteric signal in eukaryotic NCX variants, although the phenotype variances in response to regulatory Ca(2+) remain unclear. The breakthrough discovery of the archaebacterial NCX structure may serve as a template for eukaryotic NCX, although the turnover rates of the transport cycle may differ ~10(3)-fold among NCX variants to fulfill the physiological demands for the Ca(2+) flux rates. Further elucidation of ion-transport and regulatory mechanisms may lead to selective pharmacological targeting of NCX variants under disease conditions.
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Affiliation(s)
- Daniel Khananshvili
- Department of Physiology and Pharmacology, Sackler School of Medicine, Tel-Aviv University, Ramat-Aviv, Tel-Aviv, 69978, Israel,
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