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Correction: "Ryanopathies" and RyR2 dysfunctions: can we further decipher them using in vitro human disease models? Cell Death Dis 2022; 13:1014. [PMID: 36450727 PMCID: PMC9712522 DOI: 10.1038/s41419-022-05468-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
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Ono K, Iwasaki YK, Akao M, Ikeda T, Ishii K, Inden Y, Kusano K, Kobayashi Y, Koretsune Y, Sasano T, Sumitomo N, Takahashi N, Niwano S, Hagiwara N, Hisatome I, Furukawa T, Honjo H, Maruyama T, Murakawa Y, Yasaka M, Watanabe E, Aiba T, Amino M, Itoh H, Ogawa H, Okumura Y, Aoki-Kamiya C, Kishihara J, Kodani E, Komatsu T, Sakamoto Y, Satomi K, Shiga T, Shinohara T, Suzuki A, Suzuki S, Sekiguchi Y, Nagase S, Hayami N, Harada M, Fujino T, Makiyama T, Maruyama M, Miake J, Muraji S, Murata H, Morita N, Yokoshiki H, Yoshioka K, Yodogawa K, Inoue H, Okumura K, Kimura T, Tsutsui H, Shimizu W. JCS/JHRS 2020 Guideline on Pharmacotherapy of Cardiac Arrhythmias. Circ J 2022; 86:1790-1924. [DOI: 10.1253/circj.cj-20-1212] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
| | - Yu-ki Iwasaki
- Department of Cardiovascular Medicine, Nippon Medical School
| | - Masaharu Akao
- Department of Cardiovascular Medicine, National Hospital Organization Kyoto Medical Center
| | - Takanori Ikeda
- Department of Cardiovascular Medicine, Toho University Graduate School of Medicine
| | - Kuniaki Ishii
- Department of Pharmacology, Yamagata University Faculty of Medicine
| | - Yasuya Inden
- Department of Cardiology, Nagoya University Graduate School of Medicine
| | - Kengo Kusano
- Department of Cardiovascular Medicine, National Cerebral and Cardiovascular Center
| | - Yoshinori Kobayashi
- Division of Cardiology, Department of Medicine, Tokai University Hachioji Hospital
| | | | - Tetsuo Sasano
- Department of Cardiovascular Medicine, Tokyo Medical and Dental University
| | - Naokata Sumitomo
- Department of Pediatric Cardiology, Saitama Medical University International Medical Center
| | - Naohiko Takahashi
- Department of Cardiology and Clinical Examination, Faculty of Medicine, Oita University
| | - Shinichi Niwano
- Department of Cardiovascular Medicine, Kitasato University School of Medicine
| | | | | | - Tetsushi Furukawa
- Department of Bio-information Pharmacology, Medical Research Institute, Tokyo Medical and Dental University
| | - Haruo Honjo
- Research Institute of Environmental Medicine, Nagoya University
| | - Toru Maruyama
- Department of Hematology, Oncology and Cardiovascular Medicine, Kyushu University Hospital
| | - Yuji Murakawa
- The 4th Department of Internal Medicine, Teikyo University School of Medicine, Mizonokuchi Hospital
| | - Masahiro Yasaka
- Department of Cerebrovascular Medicine and Neurology, Clinical Research Institute, National Hospital Organization Kyushu Medical Center
| | - Eiichi Watanabe
- Department of Cardiology, Fujita Health University School of Medicine
| | - Takeshi Aiba
- Department of Cardiovascular Medicine, National Cerebral and Cardiovascular Center
| | - Mari Amino
- Department of Cardiovascular Medicine, Tokai University School of Medicine
| | - Hideki Itoh
- Division of Patient Safety, Hiroshima University Hospital
| | - Hisashi Ogawa
- Department of Cardiology, National Hospital Organisation Kyoto Medical Center
| | - Yasuo Okumura
- Division of Cardiology, Department of Medicine, Nihon University School of Medicine
| | - Chizuko Aoki-Kamiya
- Department of Obstetrics and Gynecology, National Cerebral and Cardiovascular Center
| | - Jun Kishihara
- Department of Cardiovascular Medicine, Kitasato University School of Medicine
| | - Eitaro Kodani
- Department of Cardiovascular Medicine, Nippon Medical School Tama Nagayama Hospital
| | - Takashi Komatsu
- Division of Cardiology, Department of Internal Medicine, Iwate Medical University School of Medicine
| | | | | | - Tsuyoshi Shiga
- Department of Clinical Pharmacology and Therapeutics, The Jikei University School of Medicine
| | - Tetsuji Shinohara
- Department of Cardiology and Clinical Examination, Faculty of Medicine, Oita University
| | - Atsushi Suzuki
- Department of Cardiology, Tokyo Women's Medical University
| | - Shinya Suzuki
- Department of Cardiovascular Medicine, The Cardiovascular Institute
| | - Yukio Sekiguchi
- Department of Cardiology, National Hospital Organization Kasumigaura Medical Center
| | - Satoshi Nagase
- Department of Cardiovascular Medicine, National Cerebral and Cardiovascular Center
| | - Noriyuki Hayami
- Department of Fourth Internal Medicine, Teikyo University Mizonokuchi Hospital
| | | | - Tadashi Fujino
- Department of Cardiovascular Medicine, Toho University, Faculty of Medicine
| | - Takeru Makiyama
- Department of Cardiovascular Medicine, Graduate School of Medicine, Kyoto University
| | - Mitsunori Maruyama
- Department of Cardiovascular Medicine, Nippon Medical School Musashi Kosugi Hospital
| | - Junichiro Miake
- Department of Pharmacology, Tottori University Faculty of Medicine
| | - Shota Muraji
- Department of Pediatric Cardiology, Saitama Medical University International Medical Center
| | | | - Norishige Morita
- Division of Cardiology, Department of Medicine, Tokai University Hachioji Hospital
| | - Hisashi Yokoshiki
- Department of Cardiovascular Medicine, Sapporo City General Hospital
| | - Koichiro Yoshioka
- Division of Cardiology, Department of Internal Medicine, Tokai University School of Medicine
| | - Kenji Yodogawa
- Department of Cardiovascular Medicine, Nippon Medical School
| | | | - Ken Okumura
- Division of Cardiology, Saiseikai Kumamoto Hospital Cardiovascular Center
| | - Takeshi Kimura
- Department of Cardiovascular Medicine, Graduate School of Medicine, Kyoto University
| | - Hiroyuki Tsutsui
- Department of Cardiovascular Medicine, Faculty of Medical Sciences, Kyushu University
| | - Wataru Shimizu
- Department of Cardiovascular Medicine, Nippon Medical School
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Guo W, Wei J, Estillore JP, Zhang L, Wang R, Sun B, Chen SRW. RyR2 disease mutations at the C-terminal domain intersubunit interface alter closed-state stability and channel activation. J Biol Chem 2021; 297:100808. [PMID: 34022226 PMCID: PMC8214192 DOI: 10.1016/j.jbc.2021.100808] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 05/14/2021] [Accepted: 05/18/2021] [Indexed: 11/19/2022] Open
Abstract
Ryanodine receptors (RyRs) are ion channels that mediate the release of Ca2+ from the sarcoplasmic reticulum/endoplasmic reticulum, mutations of which are implicated in a number of human diseases. The adjacent C-terminal domains (CTDs) of cardiac RyR (RyR2) interact with each other to form a ring-like tetrameric structure with the intersubunit interface undergoing dynamic changes during channel gating. This mobile CTD intersubunit interface harbors many disease-associated mutations. However, the mechanisms of action of these mutations and the role of CTD in channel function are not well understood. Here, we assessed the impact of CTD disease-associated mutations P4902S, P4902L, E4950K, and G4955E on Ca2+− and caffeine-mediated activation of RyR2. The G4955E mutation dramatically increased both the Ca2+-independent basal activity and Ca2+-dependent activation of [3H]ryanodine binding to RyR2. The P4902S and E4950K mutations also increased Ca2+ activation but had no effect on the basal activity of RyR2. All four disease mutations increased caffeine-mediated activation of RyR2 and reduced the threshold for activation and termination of spontaneous Ca2+ release. G4955D dramatically increased the basal activity of RyR2, whereas G4955K mutation markedly suppressed channel activity. Similarly, substitution of P4902 with a negatively charged residue (P4902D), but not a positively charged residue (P4902K), also dramatically increased the basal activity of RyR2. These data suggest that electrostatic interactions are involved in stabilizing the CTD intersubunit interface and that the G4955E disease mutation disrupts this interface, and thus the stability of the closed state. Our studies shed new insights into the mechanisms of action of RyR2 CTD disease mutations.
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Affiliation(s)
- Wenting Guo
- Libin Cardiovascular Institute, Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada
| | - Jinhong Wei
- Libin Cardiovascular Institute, Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada
| | - John Paul Estillore
- Libin Cardiovascular Institute, Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada
| | - Lin Zhang
- Libin Cardiovascular Institute, Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada
| | - Ruiwu Wang
- Libin Cardiovascular Institute, Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada
| | - Bo Sun
- Libin Cardiovascular Institute, Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada; Medical School, Kunming University of Science and Technology, Kunming, China.
| | - S R Wayne Chen
- Libin Cardiovascular Institute, Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada.
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Identification of loss-of-function RyR2 mutations associated with idiopathic ventricular fibrillation and sudden death. Biosci Rep 2021; 41:228220. [PMID: 33825858 PMCID: PMC8062958 DOI: 10.1042/bsr20210209] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2021] [Revised: 03/24/2021] [Accepted: 04/06/2021] [Indexed: 11/23/2022] Open
Abstract
Mutations in cardiac ryanodine receptor (RyR2) are linked to catecholaminergic polymorphic ventricular tachycardia (CPVT). Most CPVT RyR2 mutations characterized are gain-of-function (GOF), indicating enhanced RyR2 function as a major cause of CPVT. Loss-of-function (LOF) RyR2 mutations have also been identified and are linked to a distinct entity of cardiac arrhythmia termed RyR2 Ca2+ release deficiency syndrome (CRDS). Exercise stress testing (EST) is routinely used to diagnose CPVT, but it is ineffective for CRDS. There is currently no effective diagnostic tool for CRDS in humans. An alternative strategy to assess the risk for CRDS is to directly determine the functional impact of the associated RyR2 mutations. To this end, we have functionally screened 18 RyR2 mutations that are associated with idiopathic ventricular fibrillation (IVF) or sudden death. We found two additional RyR2 LOF mutations E4146K and G4935R. The E4146K mutation markedly suppressed caffeine activation of RyR2 and abolished store overload induced Ca2+ release (SOICR) in human embryonic kidney 293 (HEK293) cells. E4146K also severely reduced cytosolic Ca2+ activation and abolished luminal Ca2+ activation of single RyR2 channels. The G4935R mutation completely abolished caffeine activation of and [3H]ryanodine binding to RyR2. Co-expression studies showed that the G4935R mutation exerted dominant negative impact on the RyR2 wildtype (WT) channel. Interestingly, the RyR2-G4935R mutant carrier had a negative EST, and the E4146K carrier had a family history of sudden death during sleep, which are different from phenotypes of typical CPVT. Thus, our data further support the link between RyR2 LOF and a new entity of cardiac arrhythmias distinct from CPVT.
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Wang Q, Paskevicius T, Filbert A, Qin W, Kim HJ, Chen XZ, Tang J, Dacks JB, Agellon LB, Michalak M. Phylogenetic and biochemical analysis of calsequestrin structure and association of its variants with cardiac disorders. Sci Rep 2020; 10:18115. [PMID: 33093545 PMCID: PMC7582152 DOI: 10.1038/s41598-020-75097-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Accepted: 10/08/2020] [Indexed: 12/16/2022] Open
Abstract
Calsequestrin is among the most abundant proteins in muscle sarcoplasmic reticulum and displays a high capacity but a low affinity for Ca2+ binding. In mammals, calsequestrin is encoded by two genes, CASQ1 and CASQ2, which are expressed almost exclusively in skeletal and cardiac muscles, respectively. Phylogenetic analysis indicates that calsequestrin is an ancient gene in metazoans, and that the duplication of the ancestral calsequestrin gene took place after the emergence of the lancelet. CASQ2 gene variants associated with catecholaminergic polymorphic ventricular tachycardia (CPVT) in humans are positively correlated with a high degree of evolutionary conservation across all calsequestrin homologues. The mutations are distributed in diverse locations of the calsequestrin protein and impart functional diversity but remarkably manifest in a similar phenotype in humans.
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Affiliation(s)
- Qian Wang
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, T6G 2H7, Canada
| | - Tautvydas Paskevicius
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, T6G 2H7, Canada
| | - Alexander Filbert
- Division of Infectious Disease, Department of Medicine, University of Alberta, Edmonton, AB, T6G 2G3, Canada
| | - Wenying Qin
- Institute of Biomedical and Pharmaceutical Sciences, Key Laboratory of Fermentation Engineering, Hubei Provincial Cooperative Innovation Center of Industrial Fermentation, Hubei Key Laboratory of Industrial Microbiology, Hubei University of Technology, Wuhan, Hubei, China
| | - Hyeong Jin Kim
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, T6G 2H7, Canada
| | - Xing-Zhen Chen
- Institute of Biomedical and Pharmaceutical Sciences, Key Laboratory of Fermentation Engineering, Hubei Provincial Cooperative Innovation Center of Industrial Fermentation, Hubei Key Laboratory of Industrial Microbiology, Hubei University of Technology, Wuhan, Hubei, China.,Department of Physiology, University of Alberta, Edmonton, Alberta, T6G 2H7, Canada
| | - Jingfeng Tang
- Institute of Biomedical and Pharmaceutical Sciences, Key Laboratory of Fermentation Engineering, Hubei Provincial Cooperative Innovation Center of Industrial Fermentation, Hubei Key Laboratory of Industrial Microbiology, Hubei University of Technology, Wuhan, Hubei, China
| | - Joel B Dacks
- Division of Infectious Disease, Department of Medicine, University of Alberta, Edmonton, AB, T6G 2G3, Canada.
| | - Luis B Agellon
- School of Dietetics and Human Nutrition, McGill University, Ste. Anne de Bellevue, Quebec, H9X 3V9, Canada.
| | - Marek Michalak
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, T6G 2H7, Canada. .,Institute of Biomedical and Pharmaceutical Sciences, Key Laboratory of Fermentation Engineering, Hubei Provincial Cooperative Innovation Center of Industrial Fermentation, Hubei Key Laboratory of Industrial Microbiology, Hubei University of Technology, Wuhan, Hubei, China.
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Wang Q, Michalak M. Calsequestrin. Structure, function, and evolution. Cell Calcium 2020; 90:102242. [PMID: 32574906 DOI: 10.1016/j.ceca.2020.102242] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Revised: 06/05/2020] [Accepted: 06/06/2020] [Indexed: 12/25/2022]
Abstract
Calsequestrin is the major Ca2+ binding protein in the sarcoplasmic reticulum (SR), serves as the main Ca2+ storage and buffering protein and is an important regulator of Ca2+ release channels in both skeletal and cardiac muscle. It is anchored at the junctional SR membrane through interactions with membrane proteins and undergoes reversible polymerization with increasing Ca2+ concentration. Calsequestrin provides high local Ca2+ at the junctional SR and communicates changes in luminal Ca2+ concentration to Ca2+ release channels, thus it is an essential component of excitation-contraction coupling. Recent studies reveal new insights on calsequestrin trafficking, Ca2+ binding, protein evolution, protein-protein interactions, stress responses and the molecular basis of related human muscle disease, including catecholaminergic polymorphic ventricular tachycardia (CPVT). Here we provide a comprehensive overview of calsequestrin, with recent advances in structure, diverse functions, phylogenetic analysis, and its role in muscle physiology, stress responses and human pathology.
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Affiliation(s)
- Qian Wang
- Department of Biochemistry, University of Alberta, Edmonton, AB, T6H 2S7, Canada
| | - Marek Michalak
- Department of Biochemistry, University of Alberta, Edmonton, AB, T6H 2S7, Canada.
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Veith M, El-Battrawy I, Roterberg G, Raschwitz L, Lang S, Wolpert C, Schimpf R, Zhou X, Akin I, Borggrefe M. Long-Term Follow-Up of Patients with Catecholaminergic Polymorphic Ventricular Arrhythmia. J Clin Med 2020; 9:jcm9040903. [PMID: 32218223 PMCID: PMC7230751 DOI: 10.3390/jcm9040903] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2020] [Accepted: 03/10/2020] [Indexed: 11/24/2022] Open
Abstract
Background: Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a rare inherited disorder causing life-threatening arrhythmias. Long-term outcome studies of the channelopathy are limited. Objective: The aim of the present study was to summarize our knowledge on CPVT patients, including the clinical profile treatment approach and long-term outcome. Methods: In this single center study, we retrospectively and prospectively collected data from nine CPVT patients and analyzed them. Results: We reviewed nine patients with CPVT in seven families (22% male), with a median follow-up time of 8.6 years. Mean age at diagnosis was 26.4 ± 12 years. Symptoms at admission were syncope (four patients) and aborted cardiac arrest (four patients). Family history of sudden cardiac death was screened in five patients. In genetic analyses, we found five patients with ryanodine type 2 receptor (RYR2) mutations. Seven patients were treated with beta-blockers, and if symptoms persisted flecainide was added (four patients). Despite beta-blocker treatment, three patients suffered from seven adverse cardiac events. An implantable cardioverter defibrillator was implanted in seven patients (one primary, six secondary prevention). Over the follow-up period, three patients suffered from ventricular tachycardia (ten times) and five patients from ventricular fibrillation (nine times). No one died during follow-up. Conclusion: Our CPVT cohort showed a high risk of cardiac events. Family screening, optimal medical therapy and individualized treatment are necessary in affected patients in referral centers.
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Affiliation(s)
- Michael Veith
- First Department of Medicine, Faculty of Medicine, University Medical Centre Mannheim (UMM), University of Heidelberg, 68167 Mannheim, Germany; (G.R.); (L.R.); (S.L.); (C.W.); (R.S.); (X.Z.); (I.A.); (M.B.)
- Correspondence: (M.V.); (I.E.-B.)
| | - Ibrahim El-Battrawy
- First Department of Medicine, Faculty of Medicine, University Medical Centre Mannheim (UMM), University of Heidelberg, 68167 Mannheim, Germany; (G.R.); (L.R.); (S.L.); (C.W.); (R.S.); (X.Z.); (I.A.); (M.B.)
- DZHK (German Center for Cardiovascular Research), Partner Site, Heidelberg-Mannheim, 68167 Mannheim, Germany
- Correspondence: (M.V.); (I.E.-B.)
| | - Gretje Roterberg
- First Department of Medicine, Faculty of Medicine, University Medical Centre Mannheim (UMM), University of Heidelberg, 68167 Mannheim, Germany; (G.R.); (L.R.); (S.L.); (C.W.); (R.S.); (X.Z.); (I.A.); (M.B.)
| | - Laura Raschwitz
- First Department of Medicine, Faculty of Medicine, University Medical Centre Mannheim (UMM), University of Heidelberg, 68167 Mannheim, Germany; (G.R.); (L.R.); (S.L.); (C.W.); (R.S.); (X.Z.); (I.A.); (M.B.)
| | - Siegfried Lang
- First Department of Medicine, Faculty of Medicine, University Medical Centre Mannheim (UMM), University of Heidelberg, 68167 Mannheim, Germany; (G.R.); (L.R.); (S.L.); (C.W.); (R.S.); (X.Z.); (I.A.); (M.B.)
- DZHK (German Center for Cardiovascular Research), Partner Site, Heidelberg-Mannheim, 68167 Mannheim, Germany
| | - Christian Wolpert
- First Department of Medicine, Faculty of Medicine, University Medical Centre Mannheim (UMM), University of Heidelberg, 68167 Mannheim, Germany; (G.R.); (L.R.); (S.L.); (C.W.); (R.S.); (X.Z.); (I.A.); (M.B.)
| | - Rainer Schimpf
- First Department of Medicine, Faculty of Medicine, University Medical Centre Mannheim (UMM), University of Heidelberg, 68167 Mannheim, Germany; (G.R.); (L.R.); (S.L.); (C.W.); (R.S.); (X.Z.); (I.A.); (M.B.)
| | - Xiaobo Zhou
- First Department of Medicine, Faculty of Medicine, University Medical Centre Mannheim (UMM), University of Heidelberg, 68167 Mannheim, Germany; (G.R.); (L.R.); (S.L.); (C.W.); (R.S.); (X.Z.); (I.A.); (M.B.)
- DZHK (German Center for Cardiovascular Research), Partner Site, Heidelberg-Mannheim, 68167 Mannheim, Germany
| | - Ibrahim Akin
- First Department of Medicine, Faculty of Medicine, University Medical Centre Mannheim (UMM), University of Heidelberg, 68167 Mannheim, Germany; (G.R.); (L.R.); (S.L.); (C.W.); (R.S.); (X.Z.); (I.A.); (M.B.)
- DZHK (German Center for Cardiovascular Research), Partner Site, Heidelberg-Mannheim, 68167 Mannheim, Germany
| | - Martin Borggrefe
- First Department of Medicine, Faculty of Medicine, University Medical Centre Mannheim (UMM), University of Heidelberg, 68167 Mannheim, Germany; (G.R.); (L.R.); (S.L.); (C.W.); (R.S.); (X.Z.); (I.A.); (M.B.)
- DZHK (German Center for Cardiovascular Research), Partner Site, Heidelberg-Mannheim, 68167 Mannheim, Germany
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Pérez-Riera AR, Barbosa-Barros R, de Rezende Barbosa MPC, Daminello-Raimundo R, de Lucca AA, de Abreu LC. Catecholaminergic polymorphic ventricular tachycardia, an update. Ann Noninvasive Electrocardiol 2017; 23:e12512. [PMID: 29048771 DOI: 10.1111/anec.12512] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Accepted: 09/20/2017] [Indexed: 12/11/2022] Open
Abstract
Catecholaminergic polymorphic ventricular tachycardia is a rare devastating lethal inherited disorder or sporadic cardiac ion channelopathy characterized by unexplained syncopal episodes, and/or sudden cardiac death (SCD), aborted SCD (ASCD), or sudden cardiac arrest (SCA) observed in children, adolescents, and young adults without structural heart disease, consequence of adrenergically mediated arrhythmias: exercise-induced, by acute emotional stress, atrial pacing, or β-stimulant infusion, even when the electrocardiogram is normal. The entity is difficult to diagnose in the emergency department, given the range of presentations; thus, a familiarity with and high index of suspicion for this pathology are crucial. Furthermore, recognition of the characteristic findings and knowledge of the management of symptomatic patients are necessary, given the risk of arrhythmia recurrence and SCA. In this review, we will discuss the concept, epidemiology, genetic background, genetic subtypes, clinical presentation, electrocardiographic features, diagnosis criteria, differential diagnosis, and management.
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Affiliation(s)
- Andrés R Pérez-Riera
- Design of Studies and Scientific Writing Laboratory in the ABC Medicine Faculty, Santo André, São Paulo, Brazil
| | - Raimundo Barbosa-Barros
- Coronary Center of the Messejana Hospital Dr. Carlos Alberto Studart Gomes, Fortaleza, Ceará, Brazil
| | | | - Rodrigo Daminello-Raimundo
- Design of Studies and Scientific Writing Laboratory in the ABC Medicine Faculty, Santo André, São Paulo, Brazil
| | - Augusto A de Lucca
- Design of Studies and Scientific Writing Laboratory in the ABC Medicine Faculty, Santo André, São Paulo, Brazil
| | - Luiz C de Abreu
- Design of Studies and Scientific Writing Laboratory in the ABC Medicine Faculty, Santo André, São Paulo, Brazil
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McNamara C, Cullen P, Rackauskas M, Kelly R, O'Sullivan KE, Galvin J, Eaton D. Left cardiac sympathetic denervation: case series and technical report. Ir J Med Sci 2017; 186:607-613. [PMID: 28238200 DOI: 10.1007/s11845-017-1577-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Accepted: 02/02/2017] [Indexed: 11/29/2022]
Abstract
BACKGROUND Left cardiac sympathetic denervation (LCSD) is a surgical procedure that has been shown to have an antiarrhythmic and antifibrillatory effect. Evidence indicating its antiarrhythmic effect has been available for over 100 years. It involves the removal of the lower half of the stellate ganglion and T2-T4 of the sympathetic ganglia and is carried out as either a unilateral or bilateral procedure. With advancements in thoracic surgery, it can be safely performed via a minimally invasive Video-Assisted Thoracoscopic Surgery (VATS) approach resulting in significantly less morbidity and a shortened inpatient stay. LCSD provides a valuable treatment option for patients with life-threatening channelopathies and cardiomyopathies. AIMS AND METHODS This case series reports the preliminary paediatric and adult experience in the Republic of Ireland with LCSD and describes five cases recently treated in addition to an outline of the operative procedure employed. Of the five cases included, two were paediatric cases and three were adult cases. RESULTS One of the paediatric patients had a diagnosis of the rare catecholaminergic polymorphic ventricular tachycardia (CPVT) and the other a diagnosis of long-QT syndrome. Both paediatric patients experienced excellent outcomes. Of the three adult patients, two benefitted greatly and remain well at follow-up (one inappropriate sinus tachycardia and one CPVT). One patient with idiopathic ventricular fibrillation unfortunately passed away from intractable VF despite all attempts at resuscitation. CONCLUSION In this case series, we highlight that LCSD provides a critical adjunct to existing medical therapies and should be considered for all patients with life-threatening refractory arrhythmias especially those patients on maximal medical therapy.
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Affiliation(s)
- C McNamara
- Department of Cardiothoracic Surgery, Mater Misericordiae University Hospital, Eccles St., Dublin 7, Ireland
| | - P Cullen
- Department of Cardiothoracic Surgery, Mater Misericordiae University Hospital, Eccles St., Dublin 7, Ireland
| | - M Rackauskas
- Department of Cardiothoracic Surgery, Mater Misericordiae University Hospital, Eccles St., Dublin 7, Ireland
| | - R Kelly
- Department of Cardiothoracic Surgery, Our Lady's Children's Hospital, Crumlin, Dublin, Ireland
| | - K E O'Sullivan
- Department of Cardiothoracic Surgery, Mater Misericordiae University Hospital, Eccles St., Dublin 7, Ireland
| | - J Galvin
- Department of Cardiology, Mater Misericordiae University Hospital, Dublin, Ireland
| | - D Eaton
- Department of Cardiothoracic Surgery, Mater Misericordiae University Hospital, Eccles St., Dublin 7, Ireland.
- Department of Cardiothoracic Surgery, Our Lady's Children's Hospital, Crumlin, Dublin, Ireland.
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10
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Kawata H, Ohno S, Aiba T, Sakaguchi H, Miyazaki A, Sumitomo N, Kamakura T, Nakajima I, Inoue YY, Miyamoto K, Okamura H, Noda T, Kusano K, Kamakura S, Miyamoto Y, Shiraishi I, Horie M, Shimizu W. Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT) Associated With Ryanodine Receptor (RyR2) Gene Mutations - Long-Term Prognosis After Initiation of Medical Treatment. Circ J 2016; 80:1907-15. [PMID: 27452199 DOI: 10.1253/circj.cj-16-0250] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
BACKGROUND The long-term prognosis of cardiac ryanodine receptor (RyR2) positive catecholaminergic polymorphic ventricular tachycardia (CPVT) patients after initiation of medical therapy has not been well investigated. This study aimed to assess the recurrence of fatal cardiac event after initiation of medical therapy inRyR2-positive CPVT patients. METHODS AND RESULTS Thirty-fourRyR2-positive CPVT patients with a history of cardiac events were enrolled. All patients had medical treatment initiated after the first symptom or diagnosis. Exercise stress tests (ESTs) were performed to evaluate the efficacy of the medical therapy. Even after the initiation of medical therapy, high-risk ventricular arrhythmias (VAs), including premature ventricular contraction couplets, bigeminy, and ventricular tachycardia, were still induced in the majority of patients (80.6%). During 7.4 years of follow-up after the diagnosis, 7 of the 34 (20.6%) patients developed fatal cardiac events. Among those 7 patients, 6 (85.7%) were not compliant with either exercise restriction or medication therapy at the time of the events. CONCLUSIONS Even after initiation of medical treatment, high-risk VAs were induced during EST in mostRyR2-positive CPVT patients. Most fatal recurrent cardiac events occurred in patients who were noncompliant with exercise restriction and/or medical therapy. Medical management including strict exercise restriction should be emphasized to prevent recurrent cardiac event in mostRyR2-positive CPVT patients. (Circ J 2016; 80: 1907-1915).
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Affiliation(s)
- Hiro Kawata
- Division of Arrhythmia and Electrophysiology, Department of Cardiovascular Medicine, National Cerebral and Cardiovascular Center
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11
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ZHAO YT, VALDIVIA CR, GURROLA GB, HERNÁNDEZ JJ, VALDIVIA HH. Arrhythmogenic mechanisms in ryanodine receptor channelopathies. SCIENCE CHINA-LIFE SCIENCES 2014; 58:54-8. [PMID: 25480325 PMCID: PMC6309702 DOI: 10.1007/s11427-014-4778-z] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/26/2014] [Accepted: 09/10/2014] [Indexed: 11/27/2022]
Abstract
Ryanodine receptors (RyRs) are the calcium release channels of sarcoplasmic reticulum (SR) that provide the majority of cal-cium ions (Ca2+) necessary to induce contraction of cardiac and skeletal muscle cells. In their intracellular environment, RyR channels are regulated by a variety of cytosolic and luminal factors so that their output signal (Ca2+) induces finely-graded cell contraction without igniting cellular processes that may lead to aberrant electrical activity (ventricular arrhythmias) or cellular remodeling. The importance of RyR dysfunction has been recently highlighted with the demonstration that point mutations in RYR2, the gene encoding for the cardiac isoform of the RyR (RyR2), are associated with catecholaminergic polymorphic ventricular tachycardia (CPVT), an arrhythmogenic syndrome characterized by the development of adrenergically-mediated ventricular tachycardia in individuals with an apparently normal heart. Here we summarize the state of the field in regards to the main arrhythmogenic mechanisms triggered by RyR2 channels harboring mutations linked to CPVT. Most CPVT mutations characterized to date endow RyR2 channels with a gain of function, resulting in hyperactive channels that release Ca2+ spontaneously, especially during diastole. The spontaneous Ca2+ release is extruded by the electrogenic Na+/Ca2+ exchanger, which depolarizes the external membrane (delayed afterdepolarization or DAD) and may trigger untimely action potentials. However, a rare set of CPVT mutations yield RyR2 channels that are intrinsically hypo-active and hypo-responsive to stimuli, and it is unclear whether these channels release Ca2+ spontaneously during diastole. We discuss novel cellular mechanisms that appear more suitable to explain ventricular arrhythmias due to RyR2 loss-of-function mutations.
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12
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Wase A, Masood AM, Garikipati NV, Mufti O, Kabir A. Bidirectional ventricular tachycardia with myocardial infarction: a case report with insight on mechanism and treatment. Indian Heart J 2014; 66:466-9. [PMID: 25173208 DOI: 10.1016/j.ihj.2014.05.024] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2013] [Revised: 01/14/2014] [Accepted: 05/15/2014] [Indexed: 10/25/2022] Open
Abstract
Bidirectional ventricular tachycardia (BVT) is a rare variety of tachycardia with morphologically distinct presentation: The QRS axis and/or morphology is alternating in the frontal plane leads. Since its original description in association with digitalis,(1) numerous cases of this fascinating tachycardia with disparate etiologies and mechanisms have been postulated. We report a patient with BVT in association with non-ST elevation myocardial infarction and severe cardiomyopathy in the absence of digoxin toxicity.
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Affiliation(s)
- Abdul Wase
- Clinical Professor of Medicine, Wright State University Boonshoft School of Medicine, Dayton, OH, USA; Director, Electrophysiology Laboratories, Dayton Heart and Vascular Hospital at Good Samaritan Hospital, Dayton, OH, USA
| | | | - Naga V Garikipati
- Cardiology Fellow, Wright State University Boonshoft School of Medicine, Dayton, OH, USA
| | - Omar Mufti
- Cardiology Fellow, Wright State University Boonshoft School of Medicine, Dayton, OH, USA
| | - Anwarul Kabir
- Attending Physician, Good Samaritan Heart and Vascular Hospital, Dayton, OH, USA
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13
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Stathopulos PB, Seo MD, Enomoto M, Amador FJ, Ishiyama N, Ikura M. Themes and variations in ER/SR calcium release channels: structure and function. Physiology (Bethesda) 2013; 27:331-42. [PMID: 23223627 DOI: 10.1152/physiol.00013.2012] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Calcium (Ca(2+)) release from reticular stores is a vital regulatory signal in eukaryotes. Recent structural data on large NH(2)-terminal regions of IP(3)Rs and RyRs and their tetrameric arrangement in the full-length context reveal striking mechanistic similarities in Ca(2+) release channel function. A common ancestor found in unicellular genomes underscores the fundamentality of these elements to Ca(2+) release channels.
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Affiliation(s)
- Peter B Stathopulos
- Ontario Cancer Institute and Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
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14
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Singh VP, Rubinstein J, Arvanitis DA, Ren X, Gao X, Haghighi K, Gilbert M, Iyer VR, Kim DH, Cho C, Jones K, Lorenz JN, Armstrong CF, Wang HS, Gyorke S, Kranias EG. Abnormal calcium cycling and cardiac arrhythmias associated with the human Ser96Ala genetic variant of histidine-rich calcium-binding protein. J Am Heart Assoc 2013; 2:e000460. [PMID: 24125847 PMCID: PMC3835262 DOI: 10.1161/jaha.113.000460] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND A human genetic variant (Ser96Ala) in the sarcoplasmic reticulum (SR) histidine-rich Ca(2+)-binding (HRC) protein has been linked to ventricular arrhythmia and sudden death in dilated cardiomyopathy. However, the precise mechanisms affecting SR function and leading to arrhythmias remain elusive. METHODS AND RESULTS We generated transgenic mice with cardiac-specific expression of human Ala96 HRC or Ser96 HRC in the null background to assess function in absence of endogenous protein. Ala96 HRC decreased (25% to 30%) cardiomyocyte contractility and Ca2+ kinetics compared with Ser96 HRC in the absence of any structural or histological abnormalities. Furthermore, the frequency of Ca2+ waves was significantly higher (10-fold), although SR Ca2+ load was reduced (by 27%) in Ala96 HRC cells. The underlying mechanisms involved diminished interaction of Ala96 HRC with triadin, affecting ryanodine receptor (RyR) stability. Indeed, the open probability of RyR, assessed by use of ryanodine binding, was significantly increased. Accordingly, stress conditions (5 Hz plus isoproterenol) induced aftercontractions (65% in Ala96 versus 12% in Ser96) and delayed afterdepolarizations (70% in Ala96 versus 20% in Ser96). The increased SR Ca2+ leak was accompanied by hyperphosphorylation (1.6-fold) of RyR at Ser2814 by calmodulin-dependent protein kinase II. Accordingly, inclusion of the calmodulin-dependent protein kinase II inhibitor KN93 prevented Ser2814 phosphorylation and partially reversed the increases in Ca2+ spark frequency and wave production. Parallel in vivo studies revealed ventricular ectopy on short-term isoproterenol challenge and increased (4-fold) propensity to arrhythmias, including nonsustained ventricular tachycardia, after myocardial infarction in Ala96 HRC mice. CONCLUSIONS These findings suggest that aberrant SR Ca2+ release and increased susceptibility to delayed afterdepolarizations underlie triggered arrhythmic activity in human Ala96 HRC carriers.
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Affiliation(s)
- Vivek P Singh
- Department of Pharmacology and Cell Biophysics, University of Cincinnati College of Medicine, Cincinnati, OH
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15
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Jabbari J, Jabbari R, Nielsen MW, Holst AG, Nielsen JB, Haunsø S, Tfelt-Hansen J, Svendsen JH, Olesen MS. New Exome Data Question the Pathogenicity of Genetic Variants Previously Associated With Catecholaminergic Polymorphic Ventricular Tachycardia. ACTA ACUST UNITED AC 2013; 6:481-9. [DOI: 10.1161/circgenetics.113.000118] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Background—
Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a lethal, rare hereditary disease with an estimated prevalence of 1:10 000. The genetic variants that cause CPVT are usually highly penetrant. To date, about 189 variants in 5 genes (
RYR2, CASQ2, CALM1, TRND
, and
KCNJ2
) have been associated with CPVT pathogenesis.
Methods and Results—
The Exome Sequencing Project database (ESP; n= 6503) was systematically searched for previously published missense and nonsense CPVT–associated variants reported in several comprehensive reviews and in 2 databases: The Human Gene Mutation Database and The Inherited Arrhythmias Database. We used 4 different prediction tools to assess all missense variants previously associated with CPVT and compared the prediction of protein damage between CPVT-associated variants identified in the ESP and those variants not identified in the ESP. We identified 11% of the variants previously associated with CPVT in the ESP population. In the literature, 57% of these variants were reported as novel disease-causing variants absent in the healthy control subjects. These putative CPVT variants were identified in 41 out of 6131 subjects in the ESP population, corresponding to a prevalence of CPVT of up to 1:150. Using an agreement of ≥3, in silico prediction tools showed a significantly higher frequency of damaging variants among the CPVT-associated variants not identified in the ESP database (83%) compared with those variants identified in the ESP (50%;
P
=0.021).
Conclusions—
We identified a substantial overrepresentation of CPVT-associated variants in a large exome database, suggesting that these variants are not necessarily the monogenic cause of CPVT.
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Affiliation(s)
- Javad Jabbari
- From the Danish National Research Foundation Centre for Cardiac Arrhythmia (J.J., R.J., M.W.N., A.G.H., J.B.N., S.H., J.T.-H., J.H.S., M.S.O.); Laboratory for Molecular Cardiology, The Heart Centre, Rigshospitalet, Copenhagen University Hospital (J.J., R.J., M.W.N., A.G.H., J.B.N., S.H., J.T.-H., J.H.S., M.S.O.); and Department of Clinical Medicine, Faculty of Health Sciences (S.H., J.T.-H., J.H.S.), University of Copenhagen, Copenhagen, Denmark
| | - Reza Jabbari
- From the Danish National Research Foundation Centre for Cardiac Arrhythmia (J.J., R.J., M.W.N., A.G.H., J.B.N., S.H., J.T.-H., J.H.S., M.S.O.); Laboratory for Molecular Cardiology, The Heart Centre, Rigshospitalet, Copenhagen University Hospital (J.J., R.J., M.W.N., A.G.H., J.B.N., S.H., J.T.-H., J.H.S., M.S.O.); and Department of Clinical Medicine, Faculty of Health Sciences (S.H., J.T.-H., J.H.S.), University of Copenhagen, Copenhagen, Denmark
| | - Morten W. Nielsen
- From the Danish National Research Foundation Centre for Cardiac Arrhythmia (J.J., R.J., M.W.N., A.G.H., J.B.N., S.H., J.T.-H., J.H.S., M.S.O.); Laboratory for Molecular Cardiology, The Heart Centre, Rigshospitalet, Copenhagen University Hospital (J.J., R.J., M.W.N., A.G.H., J.B.N., S.H., J.T.-H., J.H.S., M.S.O.); and Department of Clinical Medicine, Faculty of Health Sciences (S.H., J.T.-H., J.H.S.), University of Copenhagen, Copenhagen, Denmark
| | - Anders G. Holst
- From the Danish National Research Foundation Centre for Cardiac Arrhythmia (J.J., R.J., M.W.N., A.G.H., J.B.N., S.H., J.T.-H., J.H.S., M.S.O.); Laboratory for Molecular Cardiology, The Heart Centre, Rigshospitalet, Copenhagen University Hospital (J.J., R.J., M.W.N., A.G.H., J.B.N., S.H., J.T.-H., J.H.S., M.S.O.); and Department of Clinical Medicine, Faculty of Health Sciences (S.H., J.T.-H., J.H.S.), University of Copenhagen, Copenhagen, Denmark
| | - Jonas B. Nielsen
- From the Danish National Research Foundation Centre for Cardiac Arrhythmia (J.J., R.J., M.W.N., A.G.H., J.B.N., S.H., J.T.-H., J.H.S., M.S.O.); Laboratory for Molecular Cardiology, The Heart Centre, Rigshospitalet, Copenhagen University Hospital (J.J., R.J., M.W.N., A.G.H., J.B.N., S.H., J.T.-H., J.H.S., M.S.O.); and Department of Clinical Medicine, Faculty of Health Sciences (S.H., J.T.-H., J.H.S.), University of Copenhagen, Copenhagen, Denmark
| | - Stig Haunsø
- From the Danish National Research Foundation Centre for Cardiac Arrhythmia (J.J., R.J., M.W.N., A.G.H., J.B.N., S.H., J.T.-H., J.H.S., M.S.O.); Laboratory for Molecular Cardiology, The Heart Centre, Rigshospitalet, Copenhagen University Hospital (J.J., R.J., M.W.N., A.G.H., J.B.N., S.H., J.T.-H., J.H.S., M.S.O.); and Department of Clinical Medicine, Faculty of Health Sciences (S.H., J.T.-H., J.H.S.), University of Copenhagen, Copenhagen, Denmark
| | - Jacob Tfelt-Hansen
- From the Danish National Research Foundation Centre for Cardiac Arrhythmia (J.J., R.J., M.W.N., A.G.H., J.B.N., S.H., J.T.-H., J.H.S., M.S.O.); Laboratory for Molecular Cardiology, The Heart Centre, Rigshospitalet, Copenhagen University Hospital (J.J., R.J., M.W.N., A.G.H., J.B.N., S.H., J.T.-H., J.H.S., M.S.O.); and Department of Clinical Medicine, Faculty of Health Sciences (S.H., J.T.-H., J.H.S.), University of Copenhagen, Copenhagen, Denmark
| | - Jesper H. Svendsen
- From the Danish National Research Foundation Centre for Cardiac Arrhythmia (J.J., R.J., M.W.N., A.G.H., J.B.N., S.H., J.T.-H., J.H.S., M.S.O.); Laboratory for Molecular Cardiology, The Heart Centre, Rigshospitalet, Copenhagen University Hospital (J.J., R.J., M.W.N., A.G.H., J.B.N., S.H., J.T.-H., J.H.S., M.S.O.); and Department of Clinical Medicine, Faculty of Health Sciences (S.H., J.T.-H., J.H.S.), University of Copenhagen, Copenhagen, Denmark
| | - Morten S. Olesen
- From the Danish National Research Foundation Centre for Cardiac Arrhythmia (J.J., R.J., M.W.N., A.G.H., J.B.N., S.H., J.T.-H., J.H.S., M.S.O.); Laboratory for Molecular Cardiology, The Heart Centre, Rigshospitalet, Copenhagen University Hospital (J.J., R.J., M.W.N., A.G.H., J.B.N., S.H., J.T.-H., J.H.S., M.S.O.); and Department of Clinical Medicine, Faculty of Health Sciences (S.H., J.T.-H., J.H.S.), University of Copenhagen, Copenhagen, Denmark
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16
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Kawamura M, Ohno S, Naiki N, Nagaoka I, Dochi K, Wang Q, Hasegawa K, Kimura H, Miyamoto A, Mizusawa Y, Itoh H, Makiyama T, Sumitomo N, Ushinohama H, Oyama K, Murakoshi N, Aonuma K, Horigome H, Honda T, Yoshinaga M, Ito M, Horie M. Genetic Background of Catecholaminergic Polymorphic Ventricular Tachycardia in Japan. Circ J 2013; 77:1705-13. [DOI: 10.1253/circj.cj-12-1460] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Mihoko Kawamura
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science
| | - Seiko Ohno
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science
| | - Nobu Naiki
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science
| | - Iori Nagaoka
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science
| | - Kenichi Dochi
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science
| | - Qi Wang
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science
| | - Kanae Hasegawa
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science
| | - Hiromi Kimura
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science
| | - Akashi Miyamoto
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science
| | - Yuka Mizusawa
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science
| | - Hideki Itoh
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science
| | - Takeru Makiyama
- Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine
| | - Naokata Sumitomo
- Department of Pediatrics and Child Health, Nihon University School of Medicine
| | - Hiroya Ushinohama
- Department of Pediatric Cardiology, Fukuoka Children’s Hospital and Medical Center for Infectious Disease
| | - Kotaro Oyama
- Department of Pediatric Cardiology, Iwate Medical University Memorial Heart Center
| | - Nobuyuki Murakoshi
- Cardiovascular Division, Graduate School of Comprehensive Human Sciences, University of Tsukuba
| | - Kazutaka Aonuma
- Cardiovascular Division, Graduate School of Comprehensive Human Sciences, University of Tsukuba
| | | | - Takafumi Honda
- Department of Pediatrics, Tokyo Women’s Medical University Yachiyo Medical Center
| | - Masao Yoshinaga
- Department of Pediatrics, National Hospital Organization Kagoshima Medical Center
| | - Makoto Ito
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science
| | - Minoru Horie
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science
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17
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Leenhardt A, Denjoy I, Guicheney P. Catecholaminergic polymorphic ventricular tachycardia. Circ Arrhythm Electrophysiol 2012; 5:1044-52. [PMID: 23022705 DOI: 10.1161/circep.111.962027] [Citation(s) in RCA: 102] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- Antoine Leenhardt
- AP-HP, Hôpital Bichat, Service de Cardiologie et Centre de Référence des Maladies Cardiaques Héréditaires, Paris, France.
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18
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Ryanodine Receptor Physiology and Its Role in Disease. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 740:217-34. [DOI: 10.1007/978-94-007-2888-2_9] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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19
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Capes EM, Loaiza R, Valdivia HH. Ryanodine receptors. Skelet Muscle 2011; 1:18. [PMID: 21798098 PMCID: PMC3156641 DOI: 10.1186/2044-5040-1-18] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2010] [Accepted: 05/04/2011] [Indexed: 12/31/2022] Open
Abstract
Excitation-contraction coupling involves the faithful conversion of electrical stimuli to mechanical shortening in striated muscle cells, enabled by the ubiquitous second messenger, calcium. Crucial to this process are ryanodine receptors (RyRs), the sentinels of massive intracellular calcium stores contained within the sarcoplasmic reticulum. In response to sarcolemmal depolarization, RyRs release calcium into the cytosol, facilitating mobilization of the myofilaments and enabling cell contraction. In order for the cells to relax, calcium must be rapidly resequestered or extruded from the cytosol. The sustainability of this cycle is crucially dependent upon precise regulation of RyRs by numerous cytosolic metabolites and by proteins within the lumen of the sarcoplasmic reticulum and those directly associated with the receptors in a macromolecular complex. In addition to providing the majority of the calcium necessary for contraction of cardiac and skeletal muscle, RyRs act as molecular switchboards that integrate a multitude of cytosolic signals such as dynamic and steady calcium fluctuations, β-adrenergic stimulation (phosphorylation), nitrosylation and metabolic states, and transduce these signals to the channel pore to release appropriate amounts of calcium. Indeed, dysregulation of calcium release via RyRs is associated with life-threatening diseases in both skeletal and cardiac muscle. In this paper, we briefly review some of the most outstanding structural and functional attributes of RyRs and their mechanism of regulation. Further, we address pathogenic RyR dysfunction implicated in cardiovascular disease and skeletal myopathies.
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Affiliation(s)
- E Michelle Capes
- Department of Cellular and Regenerative Biology, University of Wisconsin Medical School, Madison, WI 53711, USA.
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20
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Lanner JT, Georgiou DK, Joshi AD, Hamilton SL. Ryanodine receptors: structure, expression, molecular details, and function in calcium release. Cold Spring Harb Perspect Biol 2010; 2:a003996. [PMID: 20961976 DOI: 10.1101/cshperspect.a003996] [Citation(s) in RCA: 540] [Impact Index Per Article: 38.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Ryanodine receptors (RyRs) are located in the sarcoplasmic/endoplasmic reticulum membrane and are responsible for the release of Ca(2+) from intracellular stores during excitation-contraction coupling in both cardiac and skeletal muscle. RyRs are the largest known ion channels (> 2MDa) and exist as three mammalian isoforms (RyR 1-3), all of which are homotetrameric proteins that interact with and are regulated by phosphorylation, redox modifications, and a variety of small proteins and ions. Most RyR channel modulators interact with the large cytoplasmic domain whereas the carboxy-terminal portion of the protein forms the ion-conducting pore. Mutations in RyR2 are associated with human disorders such as catecholaminergic polymorphic ventricular tachycardia whereas mutations in RyR1 underlie diseases such as central core disease and malignant hyperthermia. This chapter examines the current concepts of the structure, function and regulation of RyRs and assesses the current state of understanding of their roles in associated disorders.
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Affiliation(s)
- Johanna T Lanner
- Baylor College of Medicine, Department of Molecular Physiology and Biophysics, Houston, Texas 77030,USA
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21
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Genetic variability of RyR2 and CASQ2 genes in an Asian population. Forensic Sci Int 2009; 192:53-5. [DOI: 10.1016/j.forsciint.2009.07.019] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2008] [Revised: 03/20/2009] [Accepted: 07/28/2009] [Indexed: 11/24/2022]
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22
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Beery TA, Shah MJ, Benson DW. Genetic characterization of familial CPVT after 30 years. Biol Res Nurs 2009; 11:66-72. [PMID: 19398417 DOI: 10.1177/1099800409333369] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
INTRODUCTION Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a stress-related, bidirectional ventricular tachycardia and atrial tachyarrhythmia in the absence of either structural heart disease or prolonged QT interval. Autosomal dominant and recessive forms of CPVT because of mutations in the cardiac ryanodine receptor (RyR2) or calsequestrin 2 (CASQ2) have been reported. The objective of this study was the clinical and genetic characterization of the family of an individual initially diagnosed as a child in 1978. METHOD We collected family medical history and recorded a four-generation pedigree. We performed mutation analysis of RyR2 "critical regions'' in the N-terminus, FKBP12.6 binding domain, Ca2+ binding domain, and transmembrane domains of the C-terminus by direct sequencing. RESULTS CPVT was diagnosed in two of the nine family members evaluated. Pedigree analysis suggested autosomal dominant disease transmission. There were no additional reports of seizures, pregnancy loss, neonatal death, or sudden cardiac death in family members. A novel RyR2 gene variant (W4645R) was found in four family members including two without symptoms. RyR2-W4645R segregates with disease in this family with incomplete penetrance. The W4645 residue is evolutionarily conserved in the transmembrane region adjacent to previously reported disease-causing mutations. Based on sorting intolerant from tolerant analysis of protein structure, RyR2-W4645R is predicted to be deleterious. CONCLUSIONS All current evidence supports RyR2-W4645R as a disease-causing variant, which was silent in persons for two generations before causing symptoms in persons for the next two generations, beginning in 1978.
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Affiliation(s)
- Theresa A Beery
- University of Cincinnati, and Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio 45221-0038, USA.
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23
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Marjamaa A, Laitinen-Forsblom P, Lahtinen AM, Viitasalo M, Toivonen L, Kontula K, Swan H. Search for cardiac calcium cycling gene mutations in familial ventricular arrhythmias resembling catecholaminergic polymorphic ventricular tachycardia. BMC MEDICAL GENETICS 2009; 10:12. [PMID: 19216760 PMCID: PMC2667497 DOI: 10.1186/1471-2350-10-12] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/27/2008] [Accepted: 02/12/2009] [Indexed: 11/18/2022]
Abstract
Background Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a severe inherited cardiac disorder caused by mutations predominantly in the ryanodine receptor (RyR2) gene. We sought to identify mutations in genes affecting cardiac calcium cycling in patients with CPVT and in less typical familial exercise-related ventricular arrhythmias. Methods and Results We recruited 33 consecutive patients with frequent ventricular premature complexes (VPCs) without structural heart disease and often history of syncope or sudden death in family. Sixteen of the patients featured a phenotype typical of CPVT. In 17 patients, VPCs emerged also at rest. Exercise stress test and echocardiography were performed to each patient and 232 family members. Familial background was evident in 42% of cases (n = 14). We sequenced all the coding exons of the RyR2, FKBP1B, ATP2A2 and SLC8A1 genes from the index patients. Single channel recordings of a mutant RyR2 were performed in planar lipid bilayers. Two novel RyR2 missense mutations (R1051P and S616L) and two RyR2 exon 3 deletions were identified, explaining 25% of the CPVT phenotypes. A rare variant (N3308S) with open probabilities similar to the wild type channels in vitro, was evident in a patient with resting VPCs. No disease-causing variants were detectable in the FKBP1B, ATP2A2 or SLC8A1 genes. Conclusion We report two novel CPVT-causing RyR2 mutations and a novel RyR2 variant of uncertain clinical significance in a patient with abundant resting VPCs. Our data also strengthen the previous assumption that exon 3 deletions of RyR2 should screened for in CPVT and related phenotypes.
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Affiliation(s)
- Annukka Marjamaa
- Department of Cardiology, University of Helsinki, Helsinki, Finland.
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Shephard R, Semsarian C. Advances in the prevention of sudden cardiac death in the young. Ther Adv Cardiovasc Dis 2009; 3:145-55. [DOI: 10.1177/1753944708100181] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Sudden cardiac death (SCD) is a tragic and devastating complication of a number of cardiovascular diseases. Although coronary artery disease accounts for a majority of these deaths across all ages, many other aetiologies contribute to this problem when it occurs in the young (age ≤ 35 years), where coronary artery disease is far less common. Specifically, genetic heart disorders are an important cause of SCD in the young. While pharmacological therapies have made some impact on prevention of SCD, the introduction of implantable cardioverter-defibrillator (ICD) therapy has been the single major advance in the prevention of SCD in the young. In addition, the awareness that most causes of SCD in the young are inherited, means family screening of relatives of young SCD victims allows identification of previously unrecognised at-risk individuals thereby enabling prevention of SCD in relatives. The role of genetic testing, both in living affected individuals and in the setting of a `molecular autopsy', is emerging as a key factor in early diagnosis of an underlying cardiovascular genetic disorder. Understanding the genetic basis of SCD, investigating the molecular mechanisms that lead from the gene defect to the clinical phenotype, and elucidating the specific environmental triggers for SCD, will most likely lead to further key improvements in the prevention of SCD in the young.
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Affiliation(s)
- Rhian Shephard
- Signal Transduction Group, Centenary Institute, Sydney, Australia
| | - Christopher Semsarian
- Agnes Ginges Centre for Molecular Cardiology, Centenary Institute; Department of Cardiology, Royal Prince Alfred Hospital; and Faculty of Medicine, University of Sydney, Sydney, Australia,
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DE LA FUENTE SAM, VAN LANGEN IRENEM, POSTMA ALEXV, BIKKER HENNI, MEIJER ALBERT. A Case of Catecholaminergic Polymorphic Ventricular Tachycardia Caused by Two Calsequestrin 2 Mutations. PACING AND CLINICAL ELECTROPHYSIOLOGY: PACE 2008; 31:916-9. [DOI: 10.1111/j.1540-8159.2008.01111.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Raj SR, Knollmann BC. The beat goes on—Driven by a cardiac calcium clock? Heart Rhythm 2008; 5:701-3. [DOI: 10.1016/j.hrthm.2008.02.027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2008] [Indexed: 11/26/2022]
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Sumitomo N, Sakurada H, Taniguchi K, Matsumura M, Abe O, Miyashita M, Kanamaru H, Karasawa K, Ayusawa M, Fukamizu S, Nagaoka I, Horie M, Harada K, Hiraoka M. Association of atrial arrhythmia and sinus node dysfunction in patients with catecholaminergic polymorphic ventricular tachycardia. Circ J 2007; 71:1606-9. [PMID: 17895559 DOI: 10.1253/circj.71.1606] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
BACKGROUND This study was performed to investigate the frequency and importance of supraventricular arrhythmia and sinus node (SN) dysfunction in patients with catecholaminergic polymorphic ventricular tachycardia (CPVT). METHODS AND RESULTS Eight patients with CPVT (mean age: 16.8+/-8.1 years) underwent an electrophysiological study. SN recovery time (1,389+/-394 ms) was slightly prolonged, and 4 of 8 patients had abnormal values. Atrial flutter (AF) was induced by low-rate atrial pacing in 2 patients and by isoproterenol infusion in 1 patient. Atrial fibrillation (Af) was induced by isoproterenol infusion in 2 patients. One patient presented with Af during the follow-up period, and 2 of 4 patients with AF/Af presented with increased SN recovery time. CONCLUSIONS Patients with CPVT frequently have associated with SN dysfunction, and inducible atrial tachyarrhythmias, which indicate that the pathogenesis of CPVT is limited not only to the ventricular myocardium, but also to broad regions of the heart, including the SN and atrial muscle.
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Affiliation(s)
- Naokata Sumitomo
- Department of Pediatrics, Nihon University School of Medicine, 30-1 Oyaguchi Kamimachi, Itabashi-ku, Tokyo 173-8610, Japan.
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Abstract
Sudden cardiac death is a major public health problem affecting 500,000 patients annually in the United States alone. The major risk factor for sudden cardiac death is the presence of coronary artery disease, usually in the setting of reduced ejection fraction. Globally, the incidence is expected to rise sharply as the prevalence of coronary artery disease and heart failure continue to increase. However, sudden cardiac death is a heterogeneous condition and may be caused by acute ischemia, structural defects, myocardial scar, and/or genetic mutations. Sudden death may occur even in a grossly normal heart. Beta-blockers can reduce the risk of sudden cardiac death, while implantable cardioverter defibrillators are effective at terminating malignant arrhythmias. Ejection fraction remains the major criterion to stratify patients for defibrillator implantation but this strategy alone is insensitive and nonspecific. Novel clinical, electrophysiologic, and genetic markers have been identified that may increase precision in patient selection for primary prevention therapy. This review discusses the epidemiology, mechanisms, etiologies, therapies, treatment guidelines, and future directions in the management of sudden cardiac death.
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Kim E, Youn B, Kemper L, Campbell C, Milting H, Varsanyi M, Kang C. Characterization of human cardiac calsequestrin and its deleterious mutants. J Mol Biol 2007; 373:1047-57. [PMID: 17881003 DOI: 10.1016/j.jmb.2007.08.055] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2007] [Revised: 08/17/2007] [Accepted: 08/23/2007] [Indexed: 11/16/2022]
Abstract
Mutations of conserved residues of human cardiac calsequestrin (hCSQ2), a high-capacity, low-affinity Ca2+-binding protein in the sarcoplasmic reticulum, have been associated with catecholamine-induced polymorphic ventricular tachycardia (CPVT). In order to understand the molecular mechanism and pathophysiological link between these CPVT-related missense mutations of hCSQ2 and the resulting arrhythmias, we generated three CPVT-causing mutants of hCSQ2 (R33Q, L167H, and D307H) and two non-pathological mutants (T66A and V76M) and investigated the effect of these mutations. In addition, we determined the crystal structure of the corresponding wild-type hCSQ2 to gain insight into the structural effects of those mutations. Our data show clearly that all three CPVT-related mutations lead to significant reduction in Ca2+-binding capacity in spite of the similarity of their secondary structures to that of the wild-type hCSQ2. Light-scattering experiments indicate that the Ca2+-dependent monomer-polymer transitions of the mutants are quite different, confirming that the linear polymerization behavior of CSQ is linked directly to its high-capacity Ca2+ binding. R33Q and D307H mutations result in a monomer that appears to be unable to form a properly oriented dimer. On the other hand, the L167H mutant has a disrupted hydrophobic core in domain II, resulting in high molecular aggregates, which cannot respond to Ca2+. Although one of the non-pathological mutants, T66A, shares characteristics with the wild-type, the other null mutant, V76M, shows significantly altered Ca2+-binding and polymerization behaviors, calling for careful reconsideration of its status.
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Affiliation(s)
- Eunjung Kim
- School of Molecular Biosciences, Washington State University Pullman, WA 99164-4660, USA
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30
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Abstract
Triggered activity in cardiac muscle and intracellular Ca2+ have been linked in the past. However, today not only are there a number of cellular proteins that show clear Ca2+ dependence but also there are a number of arrhythmias whose mechanism appears to be linked to Ca2+-dependent processes. Thus we present a systematic review of the mechanisms of Ca2+ transport (forward excitation-contraction coupling) in the ventricular cell as well as what is known for other cardiac cell types. Second, we review the molecular nature of the proteins that are involved in this process as well as the functional consequences of both normal and abnormal Ca2+ cycling (e.g., Ca2+ waves). Finally, we review what we understand to be the role of Ca2+ cycling in various forms of arrhythmias, that is, those associated with inherited mutations and those that are acquired and resulting from reentrant excitation and/or abnormal impulse generation (e.g., triggered activity). Further solving the nature of these intricate and dynamic interactions promises to be an important area of research for a better recognition and understanding of the nature of Ca2+ and arrhythmias. Our solutions will provide a more complete understanding of the molecular basis for the targeted control of cellular calcium in the treatment and prevention of such.
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Affiliation(s)
- Henk E D J Ter Keurs
- Department of Medicine, Physiology and Biophysics, University of Calgary, Alberta, Canada
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31
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Dirksen WP, Lacombe VA, Chi M, Kalyanasundaram A, Viatchenko-Karpinski S, Terentyev D, Zhou Z, Vedamoorthyrao S, Li N, Chiamvimonvat N, Carnes CA, Franzini-Armstrong C, Györke S, Periasamy M. A mutation in calsequestrin, CASQ2D307H, impairs Sarcoplasmic Reticulum Ca2+ handling and causes complex ventricular arrhythmias in mice. Cardiovasc Res 2007; 75:69-78. [PMID: 17449018 PMCID: PMC2717009 DOI: 10.1016/j.cardiores.2007.03.002] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/06/2006] [Revised: 02/19/2007] [Accepted: 03/02/2007] [Indexed: 11/20/2022] Open
Abstract
OBJECTIVE A naturally-occurring mutation in cardiac calsequestrin (CASQ2) at amino acid 307 was discovered in a highly inbred family and hypothesized to cause Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT). The goal of this study was to establish a causal link between CASQ2(D307H) and the CPVT phenotype using an in vivo model. METHODS AND RESULTS Cardiac-specific expression of the CASQ2(D307H) transgene was achieved using the alpha-MHC promoter. Multiple transgenic (TG) mouse lines expressing CASQ2(D307H) from 2- to 6-fold possess structurally normal hearts without any sign of hypertrophy. The hearts displayed normal ventricular function. Myocytes isolated from TG mice had diminished I(Ca)-induced Ca2+ transient amplitude and duration, as well as increased Ca2+ spark frequency. These myocytes, when exposed to isoproterenol and caffeine, displayed disturbances in their rhythmic Ca2+ oscillations and membrane potential, and delayed afterdepolarizations. ECG monitoring revealed that TG mice challenged with isoproterenol and caffeine developed complex ventricular arrhythmias, including non-sustained polymorphic ventricular tachycardia. CONCLUSIONS The findings of the present study demonstrate that expression of mutant CASQ2(D307H) in the mouse heart results in abnormal myocyte Ca2+ handling and predisposes to complex ventricular arrhythmias similar to the CPVT phenotype observed in human patients.
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MESH Headings
- Animals
- Caffeine/pharmacology
- Calcium/metabolism
- Calcium Signaling
- Calsequestrin/genetics
- Cardiotonic Agents/pharmacology
- Death, Sudden, Cardiac/etiology
- Electrocardiography
- Isoproterenol/pharmacology
- Mice
- Mice, Transgenic
- Microscopy, Confocal
- Models, Animal
- Mutation, Missense
- Myocytes, Cardiac/metabolism
- Myocytes, Cardiac/pathology
- Sarcoplasmic Reticulum/metabolism
- Tachycardia, Ventricular/genetics
- Tachycardia, Ventricular/metabolism
- Tachycardia, Ventricular/pathology
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Affiliation(s)
- Wessel P. Dirksen
- Department of Physiology and Cell Biology, The Ohio State University, Columbus, OH 43210
| | | | - Mei Chi
- Department of Physiology and Cell Biology, The Ohio State University, Columbus, OH 43210
| | | | - Serge Viatchenko-Karpinski
- Department of Physiology and Cell Biology, The Ohio State University, Columbus, OH 43210
- Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210
| | - Dmitry Terentyev
- Department of Physiology and Cell Biology, The Ohio State University, Columbus, OH 43210
- Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210
| | - Zhixiang Zhou
- Department of Physiology and Cell Biology, The Ohio State University, Columbus, OH 43210
| | - Srikanth Vedamoorthyrao
- Department of Physiology and Cell Biology, The Ohio State University, Columbus, OH 43210
- Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210
| | - Ning Li
- Division of Cardiovascular Medicine, University of California, Davis, CA 95616
| | | | | | - Clara Franzini-Armstrong
- Department of Cell and Developmental Biology, University of Pennsylvania, Philadelphia, PA 19104
| | - Sandor Györke
- Department of Physiology and Cell Biology, The Ohio State University, Columbus, OH 43210
- Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210
| | - Muthu Periasamy
- Department of Physiology and Cell Biology, The Ohio State University, Columbus, OH 43210
- Corresponding Author: Dept. of Physiology and Cell Biology, 304 Hamilton Hall, 1645 Neil Ave, The Ohio State University College of Medicine, Columbus, OH 43210. Tel.: 614-292-2310; Fax: 614-292-4888;
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Thomas NL, George CH, Lai FA. Role of ryanodine receptor mutations in cardiac pathology: more questions than answers? Biochem Soc Trans 2007; 34:913-8. [PMID: 17052226 DOI: 10.1042/bst0340913] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The RyR (ryanodine receptor) mediates rapid Ca2+ efflux from the ER (endoplasmic reticulum) and is responsible for triggering numerous Ca2+-activated physiological processes. The most studied RyR-mediated process is excitation-contraction coupling in striated muscle, where plasma membrane excitation is transmitted to the cell interior and results in Ca2+ efflux that triggers myocyte contraction. Recently, single-residue mutations in the cardiac RyR (RyR2) have been identified in families that exhibit CPVT (catecholaminergic polymorphic ventricular tachycardia), a condition in which physical or emotional stress can trigger severe tachyarrhythmias that can lead to sudden cardiac death. The RyR2 mutations in CPVT are clustered in the N- and C-terminal domains, as well as in a central domain. Further, a critical signalling role for dysfunctional RyR2 has also been implicated in the generation of arrhythmias in the common condition of HF (heart failure). We have prepared cardiac RyR2 plasmids with various CPVT mutations to enable expression and analysis of Ca2+ release mediated by the wild-type and mutated RyR2. These studies suggest that the mutational locus may be important in the mechanism of Ca2+ channel dysfunction. Understanding the causes of aberrant Ca2+ release via RyR2 may assist in the development of effective treatments for the ventricular arrhythmias that often leads to sudden death in HF and in CPVT.
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Affiliation(s)
- N L Thomas
- Department of Cardiology, Wales Heart Research Institute, School of Medicine, Cardiff University, Cardiff CF14 4XN, UK.
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Yuan Q, Fan GC, Dong M, Altschafl B, Diwan A, Ren X, Hahn HH, Zhao W, Waggoner JR, Jones LR, Jones WK, Bers DM, Dorn GW, Wang HS, Valdivia HH, Chu G, Kranias EG. Sarcoplasmic reticulum calcium overloading in junctin deficiency enhances cardiac contractility but increases ventricular automaticity. Circulation 2007; 115:300-9. [PMID: 17224479 DOI: 10.1161/circulationaha.106.654699] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Abnormal sarcoplasmic reticulum calcium (Ca) cycling is increasingly recognized as an important mechanism for increased ventricular automaticity that leads to lethal ventricular arrhythmias. Previous studies have linked lethal familial arrhythmogenic disorders to mutations in the ryanodine receptor and calsequestrin genes, which interact with junctin and triadin to form a macromolecular Ca-signaling complex. The essential physiological effects of junctin and its potential regulatory roles in sarcoplasmic reticulum Ca cycling and Ca-dependent cardiac functions, such as myocyte contractility and automaticity, are unknown. METHODS AND RESULTS The junctin gene was targeted in embryonic stem cells, and a junctin-deficient mouse was generated. Ablation of junctin was associated with enhanced cardiac function in vivo, and junctin-deficient cardiomyocytes exhibited increased contractile and Ca-cycling parameters. Short-term isoproterenol stimulation elicited arrhythmias, including premature ventricular contractions, atrioventricular heart block, and ventricular tachycardia. Long-term isoproterenol infusion also induced premature ventricular contractions and atrioventricular heart block in junctin-null mice. Further examination of the electrical activity revealed a significant increase in the occurrence of delayed afterdepolarizations. Consistently, 25% of the junctin-null mice died by 3 months of age with structurally normal hearts. CONCLUSIONS Junctin is an essential regulator of sarcoplasmic reticulum Ca release and contractility in normal hearts. Ablation of junctin is associated with aberrant Ca homeostasis, which leads to fatal arrhythmias. Thus, normal intracellular Ca cycling relies on maintenance of junctin levels and an intricate balance among the components in the sarcoplasmic reticulum quaternary Ca-signaling complex.
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Affiliation(s)
- Qunying Yuan
- Department of Pharmacology and Cell Biophysics, University of Cincinnati College of Medicine, Cincinnati, OH 45267-0575, USA
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Durham WJ, Wehrens XHT, Sood S, Hamilton SL. Diseases associated with altered ryanodine receptor activity. Subcell Biochem 2007; 45:273-321. [PMID: 18193641 DOI: 10.1007/978-1-4020-6191-2_10] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Mutations in two intracellular Ca2+ release channels or ryanodine receptors (RyR1 and RyR2) are associated with a number of human skeletal and cardiac diseases. This chapter discusses these diseases in terms of known mechanisms, controversies, and unanswered questions. We also compare the cardiac and skeletal muscle diseases to explore common mechanisms.
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Affiliation(s)
- W J Durham
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX 77030, USA
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35
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George CH, Jundi H, Thomas NL, Fry DL, Lai FA. Ryanodine receptors and ventricular arrhythmias: emerging trends in mutations, mechanisms and therapies. J Mol Cell Cardiol 2006; 42:34-50. [PMID: 17081562 DOI: 10.1016/j.yjmcc.2006.08.115] [Citation(s) in RCA: 130] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/07/2006] [Accepted: 08/30/2006] [Indexed: 11/25/2022]
Abstract
It has been six years since the first reported link between mutations in the cardiac ryanodine receptor Ca(2+) release channel (RyR2) and catecholaminergic polymorphic ventricular tachycardia (CPVT), a malignant stress-induced arrhythmia. In this time, rapid advances have been made in identifying new mutations, and in understanding how these mutations disrupt normal channel function to cause VT that frequently degenerates into ventricular fibrillation (VF) and sudden death. Functional characterisation of these RyR2 Ca(2+) channelopathies suggests that mutations alter the ability of RyR2 to sense its intracellular environment, and that channel modulation via covalent modification, Ca(2+)- and Mg(2+)-dependent regulation and structural feedback mechanisms are catastrophically disturbed. This review reconciles the current status of RyR2 mutation-linked etiopathology, the significance of mutational clustering within the RyR2 polypeptide and the mechanisms underlying channel dysfunction. We will also review new data that explores the link between abnormal Ca(2+) release and the resultant cardiac electrical instability in VT and VF, and how these recent developments impact on novel anti-arrhythmic therapies. Finally, we evaluate the concept that mechanistic differences between CPVT and other arrhythmogenic disorders may preclude a common therapeutic strategy to normalise RyR2 function in cardiac disease.
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Affiliation(s)
- Christopher H George
- Department of Cardiology, Wales Heart Research Institute, Cardiff University School of Medicine, Heath Park, Cardiff CF14 4XN, UK.
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Dulhunty AF, Beard NA, Pouliquin P, Kimura T. Novel regulators of RyR Ca2+ release channels: insight into molecular changes in genetically-linked myopathies. J Muscle Res Cell Motil 2006; 27:351-65. [PMID: 16909197 DOI: 10.1007/s10974-006-9086-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2006] [Accepted: 06/26/2006] [Indexed: 10/24/2022]
Abstract
There are many mutations in the ryanodine receptor (RyR) Ca2+ release channel that are implicated in skeletal muscle disorders and cardiac arrhythmias. More than 80 mutations in the skeletal RyR1 have been identified and linked to malignant hyperthermia, central core disease or multi-minicore disease, while more than 40 mutations in the cardiac RyR2 lead to ventricular arrhythmias and sudden cardiac death in patients with structurally normal hearts. These RyR mutations cause diverse changes in RyR activity which either excessively activate or block the channel in a manner that disrupts Ca2+ signalling in the muscle fibres. In a different myopathy, myotonic dystrophy (DM), a juvenile isoform of the skeletal RyR is preferentially expressed in adults. There are two regions of RyR1 that are variably spiced and developmentally regulated (ASI and ASII). The juvenile isoform (ASI(-)) is less active than the adult isoform (ASI(+)) and its over-expression in adults with DM may contribute to functional changes. Finally, mutations in an important regulator of the RyR, the Ca2+ binding protein calsequestrin (CSQ), have been linked to a disruption of Ca2+ homeostasis in cardiac myocytes that results in arrhythmias. We discuss evidence supporting the hypothesis that mutations in each of these situations alter protein/protein interactions within the RyR complex or between the RyR and its associated proteins. The disruption of these protein-protein interactions can lead either to excess Ca2+ release or reduced Ca2+ release and thus to abnormal Ca2+ homeostasis. Much of the evidence for disruption of protein-protein interactions has been provided by the actions of a group of novel RyR regulators, domain peptides with sequences that correspond to sequences within the RyR and which compete with the endogenous residues for their interaction sites.
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Affiliation(s)
- A F Dulhunty
- Division of Molecular Bioscience, JCSMR and RSC, ANU, Canberra, ACT, 2601, Australia.
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Abstract
Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a heart muscle disease in which the pathological substrate is a fibro-fatty replacement of the right ventricular myocardium. The major clinical features are different types of arrhythmias with a left branch block pattern. ARVC shows autosomal dominant inheritance with incomplete penetrance. Recessive forms were also described, although in association with skin disorders. Ten genetic loci have been discovered so far and mutations were reported in five different genes. ARVD1 was associated with regulatory mutations of transforming growth factor beta-3 (TGFβ3), whereas ARVD2, characterized by effort-induced polymorphic arrhythmias, was associated with mutations in cardiac ryanodine receptor-2 (RYR2). All other mutations identified to date have been detected in genes encoding desmosomal proteins: plakoglobin (JUP) which causes Naxos disease (a recessive form of ARVC associated with palmoplantar keratosis and woolly hair); desmoplakin (DSP) which causes the autosomal dominant ARVD8 and plakophilin-2 (PKP2) involved in ARVD9. Desmosomes are important cell-to-cell adhesion junctions predominantly found in epidermis and heart; they are believed to couple cytoskeletal elements to plasma membrane in cell-to-cell or cell-to-substrate adhesions.
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Scheinman MM, Lam J. Exercise-induced ventricular arrhythmias in patients with no structural cardiac disease. Annu Rev Med 2006; 57:473-84. [PMID: 16409161 DOI: 10.1146/annurev.med.57.081704.090151] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
We review the clinical and genetic disorders associated with exercise-induced ventricular arrhythmias in patients with normal hearts. Foremost are those with catecholaminergic polymorphic ventricular tachycardia due to abnormalities in either the ryanodine receptor 2 genes (RyR2) or the calsequestrin genes (CASQ). These patients manifest ventricular premature beats and polymorphic ventricular tachycardia in response to exercise or on exposure to catecholamines. A great deal of basic information has been accumulated suggesting that these arrhythmias are caused by abnormalities in Ca2+ metabolism. The ensuing cytosolic Ca2+ overload results in delayed after-depolarizations and extrasystolic Ca2+ waves, leading to polymorphic ventricular tachycardia. Most of these patients will respond to beta-blocker therapy but a significant minority (30%) will require a defibrillator. Advances in genetic testing allow better understanding of this syndrome.
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Affiliation(s)
- Melvin M Scheinman
- Department of Medicine, University of California San Francisco, San Francisco, California 94143, USA.
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40
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Boyden PA, ter Keurs H. Would modulation of intracellular Ca2+ be antiarrhythmic? Pharmacol Ther 2005; 108:149-79. [PMID: 16038982 DOI: 10.1016/j.pharmthera.2005.03.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2005] [Accepted: 03/22/2005] [Indexed: 01/10/2023]
Abstract
Under several types of conditions, reversal of steps of excitation-contraction coupling (RECC) can give rise to nondriven electrical activity. In this review we explore those conditions for several cardiac cell types (SA, atrial, Purkinje, ventricular cells). We find that abnormal spontaneous Ca2+ release from intracellular Ca2+ stores, aberrant Ca2+ influx from sarcolemmal channels or abnormal Ca2+ surges in nonuniform muscle can be the initiators of the RECC. Often, with such increases in Ca2+, spontaneous Ca2+ waves occur and lead to membrane depolarizations. Because the change in membrane voltage is produced by Ca2+-dependent changes in ion channel function, we also review here what is known about the molecular interaction of Ca2+ and several Ca2+-dependent processes, including the intracellular Ca2+ release channels implicated in the genetic basis of some forms of human arrhythmias. Finally, we review what is known about the effectiveness of several agents in modifying such Ca2+-dependent arrhythmias.
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Affiliation(s)
- Penelope A Boyden
- Department of Pharmacology, Center for Molecular Therapeutics, Columbia University, NY 10032, USA.
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Liu Z, Wang R, Zhang J, Chen SRW, Wagenknecht T. Localization of a disease-associated mutation site in the three-dimensional structure of the cardiac muscle ryanodine receptor. J Biol Chem 2005; 280:37941-7. [PMID: 16157601 PMCID: PMC1470666 DOI: 10.1074/jbc.m505714200] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The cardiac muscle ryanodine receptor (RyR2) functions as a calcium release channel in the heart. Up to 40 mutations in RyR2 have been linked to genetic forms of sudden cardiac death. These mutations are largely clustered in three regions of the sequence of the polypeptide: one near the N terminus, one in the central region, and the third in the C-terminal region. The central region includes 11 mutations, and an isoleucine-proline motif (positions 2427 and 2428) in the same region is predicted to contribute to the binding of FKBP12.6 protein. We have mapped the central mutation site in the three-dimensional structure of RyR2 by green fluorescent protein insertion, cryoelectron microscopy, and single-particle image processing. The central mutation site was mapped to a "bridge" of density that connects cytoplasmic domains 5 and 6, which have been suggested to undergo conformational changes during channel gating. Moreover, the location of this central mutation site is not close to that of the FKBP12.6-binding site mapped previously by cryoelectron microscopy.
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Affiliation(s)
- Zheng Liu
- Wadsworth Center, New York State Department of Health, Albany, 12201, USA.
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42
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Yano M, Yamamoto T, Ikemoto N, Matsuzaki M. Abnormal ryanodine receptor function in heart failure. Pharmacol Ther 2005; 107:377-91. [PMID: 15951021 DOI: 10.1016/j.pharmthera.2005.04.003] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2005] [Accepted: 04/13/2005] [Indexed: 11/16/2022]
Abstract
The abnormally regulated release of Ca2+ from an intracellular Ca2+ store, the sarcoplasmic reticulum (SR), is the mechanism underlying contractile and relaxation dysfunctions in heart failure (HF). According to recent reports, protein kinase A (PKA)-mediated hyperphosphorylation of ryanodine receptor (RyR) in the SR has been shown to cause the dissociation of FK506 binding protein (FKBP) 12.6 from the RyR in heart failure. This causes an abnormal Ca2+ leak through the Ca2+ channel located in the RyR, leading to an increase in the cytosolic Ca2+ during diastole, prolongation of the Ca2+ transient, and delayed/slowed diastolic Ca2+ re-uptake. More recently, a considerable number of disease-linked mutations in the RyR have been reported in patients with catecholaminergic polymorphic ventricular tachycardia (CPVT) or arrhythmogenic right ventricular dysplasia type 2. An analysis of the disposition of these mutation sites within well-defined domains of the RyR polypeptide chain has led to the new concept that interdomain interactions among these domains play a critical role in channel regulation, and an altered domain interaction causes channel dysfunction in the failing heart. The knowledge gained from the recent literature concerning the critical proteins and the changes in their properties under pathological conditions has brought us to a better position to develop new pharmacological or genetic strategies for the treatment of heart failure or cardiac arrhythmia. A considerable body of evidence reviewed here indicates that abnormal RyR function plays an important role in the pathogenesis of heart failure. This review also covers some controversial issues in the literature concerning the involvement of phosphorylation and FKBP12.6.
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Affiliation(s)
- Masafumi Yano
- Department of Medical Bioregulation, Division of Cardiovascular Medicine, Yamaguchi University School of Medicine, Yamaguchi, Japan.
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43
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Abstract
RyRs are large homotetrameric proteins that are approximately 4/5 cytoplasmic and approximately 1/5 transmembrane and luminal in mass. Mutations in RyRs produce human disease and many of these disease-causing mutations are in the cytoplasmic domains. To elucidate the mechanisms of a disease and to develop interventions, it is crucial to determine how the alterations in the cytoplasmic domains communicate with the transmembrane pore of this channel. One of the major activators of all three RyR isoforms is Ca2+ and some of the disease-causing mutations are thought to alter the sensitivity of the channels to Ca2+ activation. This review examines the current state of structural understanding of the RyR channel activation.
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Affiliation(s)
- Susan L Hamilton
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA.
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44
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George CH, Thomas NL, Lai FA. Ryanodine receptor dysfunction in arrhythmia and sudden cardiac death. Future Cardiol 2005; 1:531-41. [DOI: 10.2217/14796678.1.4.531] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Mutations in ryanodine receptor calcium ion-release channels (RyR2) have emerged as important causative players in exercise/stress-induced ventricular arrhythmia leading to sudden cardiac death (SCD). Thus, RyR2 represents an attractive therapeutic target, and a detailed understanding of the mechanistic basis of RyR2 dysfunction at the molecular, cellular and organ level is essential for the development of novel, more effective therapeutic approaches to prevent arrhythmia and SCD. Such advances will translate into a tremendous improvement in the survival and quality of life of SCD-susceptible individuals. In this review, the authors consider how recent knowledge gained from mutation identification, phenotypic manifestation and functional evaluation of RyR2 mutants, are being used to develop novel therapeutic strategies in RyR2-dependent arrhythmia.
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Affiliation(s)
- Christopher H George
- Cardiff University School of Medicine, Department of Cardiology, Wales Heart Research Institute, Heath Park, Cardiff, CF14 4XN, UK
| | - N Lowri Thomas
- Cardiff University School of Medicine, Department of Cardiology, Wales Heart Research Institute, Heath Park, Cardiff, CF14 4XN, UK
| | - F Anthony Lai
- Cardiff University School of Medicine, Department of Cardiology, Wales Heart Research Institute, Heath Park, Cardiff, CF14 4XN, UK
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d'Amati G, Bagattin A, Bauce B, Rampazzo A, Autore C, Basso C, King K, Romeo MD, Gallo P, Thiene G, Danieli GA, Nava A. Juvenile sudden death in a family with polymorphic ventricular arrhythmias caused by a novel RyR2 gene mutation: evidence of specific morphological substrates. Hum Pathol 2005; 36:761-7. [PMID: 16084945 DOI: 10.1016/j.humpath.2005.04.019] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/19/2005] [Accepted: 04/25/2005] [Indexed: 11/27/2022]
Abstract
We report on a family with a history of sudden death and effort-induced polymorphic ventricular arrhythmias. The index case was a 17-year-old boy who died suddenly and at postmortem had evidence of fibrofatty replacement in the right ventricular free wall, consistent with arrhythmogenic right ventricular cardiomyopathy, as well as calcium phosphate deposits within the myocytes. A molecular genetics investigation carried out in the paraffin-embedded myocardium of the subject and in blood samples of family members disclosed a missense mutation in exon 3 (230C-->T; A77V) of the cardiac ryanodine receptor type 2 gene. The carriers showed effort-induced polymorphic ventricular tachycardia in the setting of normal resting electrocardiogram and trivial echocardiographic abnormalities, consistent with catecholaminergic polymorphic ventricular tachycardia. The observation of both arrhythmogenic right ventricular cardiomyopathy type 2 and catecholaminergic polymorphic ventricular tachycardia in the same family suggests that the two entities might correspond to different degrees of phenotypic expression of the same disease. This experience underscores the importance of a precise autopsy diagnosis in the case of sudden cardiac death, including molecular genetics, and the mission of pathologists to guide further clinical investigation of family members.
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Affiliation(s)
- Giulia d'Amati
- Department of Experimental Medicine and Pathology, La Sapienza University, Rome 00161, Italy
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46
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Yano M, Ikeda Y, Matsuzaki M. Altered intracellular Ca2+ handling in heart failure. J Clin Invest 2005; 115:556-64. [PMID: 15765137 PMCID: PMC1052007 DOI: 10.1172/jci24159] [Citation(s) in RCA: 144] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Structural and functional alterations in the Ca2+ regulatory proteins present in the sarcoplasmic reticulum have recently been shown to be strongly involved in the pathogenesis of heart failure. Chronic activation of the sympathetic nervous system or of the renin-angiotensin system induces abnormalities in both the function and structure of these proteins. We review here the considerable body of evidence that has accumulated to support the notion that such abnormalities contribute to a defectiveness of contractile performance and hence to the progression of heart failure.
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Affiliation(s)
- Masafumi Yano
- Department of Medical Bioregulation, Division of Cardiovascular Medicine, Yamaguchi University School of Medicine, Yamaguchi, Japan
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47
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Francis J, Sankar V, Nair VK, Priori SG. Catecholaminergic polymorphic ventricular tachycardia. Heart Rhythm 2005; 2:550-4. [PMID: 15840485 DOI: 10.1016/j.hrthm.2005.01.024] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/09/2004] [Accepted: 01/18/2005] [Indexed: 12/22/2022]
Abstract
Catecholaminergic polymorphic ventricular tachycardia (VT) is a rare arrhythmogenic disease characterized by exercise- or stress-induced ventricular tachyarrhythmias, syncope, or sudden death, usually in the pediatric age group. Familial occurrence has been noted in about 30% of cases. Inheritance can be autosomal dominant or recessive, usually with high penetrance. The causative genes have been mapped to chromosome 1. Mutations of the cardiac ryanodine receptor gene (RyR2) have been identified in autosomal dominant pedigrees, while calsequestrin gene (CASQ2) mutations are seen in recessive cases. Ankyrin-B mutations may also be implicated in catecholaminergic polymorphic VT: mutations in this gene were previously linked to the long-QT 4 phenotype. Ventricular ectopy, bidirectional VT, and polymorphic VT occur in a predictable and progressive manner with increasing heart rate during exercise or isoproterenol infusion. Estimated mortality of untreated cases ranges from 30% to 50% before the age of 20-30 years according to family studies. Although beta-blocker therapy was considered to be effective in preventing clinical recurrence in the initial series, recent data show low efficacy. As there is a chance for sudden cardiac death if even a single dose of beta-blocker is missed, there is a trend toward implantation of defibrillators in more and more patients.
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Affiliation(s)
- Johnson Francis
- Department of Cardiology, Medical College Calicut, Kerala, India.
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Thomas NL, Lai FA, George CH. Differential Ca2+ sensitivity of RyR2 mutations reveals distinct mechanisms of channel dysfunction in sudden cardiac death. Biochem Biophys Res Commun 2005; 331:231-8. [PMID: 15845383 DOI: 10.1016/j.bbrc.2005.02.194] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2005] [Indexed: 11/24/2022]
Abstract
Arrhythmogenic point mutations in RyR2 result in abnormal Ca(2+) release following cardiac stimulation, leading to sudden cardiac death (SCD). Recently, we have demonstrated that significant functional differences exist between SCD-linked RyR2 mutations. Here, we investigated the molecular basis of this heterogeneity and determined the sensitivity of mutant RyR2 channels to cytoplasmic [Ca(2+)] ([Ca(2+)](c)) in living cells. Using streptolysin-O permeabilised human embryonic kidney cells, [Ca(2+)](c) was clamped in cells expressing GFP-tagged wild-type (WT) or SCD-linked RyR2 mutants (L(433)P, N(2386)I, and R(176)Q/T(2504)M). Although resting [Ca(2+)](c) was comparable in all cells, RyR2 mutants were characterised by a profound loss of Ca(2+)-dependent inhibition following caffeine stimulation when compared with WT channels. The ER Ca(2+) store was not perturbed in these experiments. Our findings support the hypothesis that SCD-linked mutational loci may be an important mechanistic determinant of RyR2 dysfunction and indicate that there is unlikely to be a unifying mechanism for channel dysfunction in SCD.
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Affiliation(s)
- N Lowri Thomas
- Department of Cardiology, Wales Heart Research Institute, Cardiff University School of Medicine, Cardiff, Wales CF14 4XN, UK
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Allouis M, Probst V, Jaafar P, Schott JJ, Le Marec H. Unusual clinical presentation in a family with catecholaminergic polymorphic ventricular tachycardia due to a G14876A ryanodine receptor gene mutation. Am J Cardiol 2005; 95:700-2. [PMID: 15721128 DOI: 10.1016/j.amjcard.2004.10.057] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/05/2004] [Revised: 10/14/2004] [Accepted: 10/14/2004] [Indexed: 11/24/2022]
Abstract
A family was identified, of whom which 11 members were carriers of the G14876A ryanodine 2 receptor mutation. All but 1 were symptomatic at the time of the study. Exercise testing showed bidirectional or polymorphic arrhythmias in 4 patients, whereas in 5 patients, it showed monomorphic or rare minor polymorphic ventricular arrhythmias. Two young patients died suddenly at rest while asleep. This study demonstrates that arrhythmias occurring during exercise stress testing in patients affected by catecholaminergic polymorphic ventricular tachycardia (CPVT) could be minor even in very symptomatic patients. The diagnosis of CPVT must be considered in these patients with a familial history of typical CPVT.
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Swan H, Laitinen P, Kontula K, Toivonen L. Calcium channel antagonism reduces exercise-induced ventricular arrhythmias in catecholaminergic polymorphic ventricular tachycardia patients with RyR2 mutations. J Cardiovasc Electrophysiol 2005; 16:162-6. [PMID: 15720454 DOI: 10.1046/j.1540-8167.2005.40516.x] [Citation(s) in RCA: 107] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
UNLABELLED Calcium channel antagonism in RyR2 defects. INTRODUCTION Recently, gain-of-function mutations of cardiac ryanodine receptor RyR2 gene have been identified as a cause of familial or catecholaminergic polymorphic ventricular tachycardia. We examined the influence of the calcium channel blockers, verapamil and magnesium, on exercise-induced ventricular arrhythmias in patients with RyR2 mutations. METHODS AND RESULTS Six molecularly defined catecholaminergic polymorphic ventricular tachycardia patients, all carrying a RyR2 mutation and on beta-adrenergic blocker therapy, underwent exercise stress test four times: at baseline, after verapamil and magnesium sulphate infusions, and finally, without interventions. The number of isolated and successive premature ventricular complexes during exercise ranged from 40 to 374 beats (mean 165 beats) at baseline, and was reduced during verapamil by 76+/-17% (P<0.05). Premature ventricular complexes appeared later and at higher heart rate during verapamil than at baseline (119+/-21 vs. 127+/-27 min-1, P<0.05). Magnesium did not inhibit the arrhythmias. Results in the fourth exercise stress test without interventions were similar to those in the first baseline study. CONCLUSIONS This study provides the first in vivo demonstration that a calcium channel antagonist, verapamil, can suppress premature ventricular complexes and nonsustained ventricular salvoes in catecholaminergic polymorphic ventricular tachycardia caused by RyR2 mutations. Modifying the abnormal calcium handling by calcium antagonists might have therapeutic value.
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Affiliation(s)
- Heikki Swan
- Department of Cardiology, Helsinki University Central Hospital, Helsinki, Finland.
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