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Lu M, Li S, Han Z, Ma B, Wang L, Wan F, Lei S, Nie Y, Wang J. Carrying both the heterozygous Myh6-R453C and Tnnt2-R92W mutations aggravate the hypertrophic cardiomyopathy phenotype in mice. Biochem Biophys Res Commun 2024; 733:150582. [PMID: 39191188 DOI: 10.1016/j.bbrc.2024.150582] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2024] [Revised: 08/04/2024] [Accepted: 08/20/2024] [Indexed: 08/29/2024]
Abstract
Hypertrophic cardiomyopathy (HCM) is an inherited disease of the heart muscle that is dominated by variations in eight genes encoding sarcomere proteins. Although there are clinical or basic research reports that carrying double mutations can lead to more severe HCM phenotypes, there are also research reports that after reanalyzing the reported mutations, the severity of clinical symptoms in patients with double mutations did not significantly increase compared to patients with only one mutation. To determine whether double pathogenic mutations can aggravate the phenotype of hypertrophic cardiomyopathy in mice, we constructed mice carrying single pathogenic heterozygous mutation Myh6-R453C or Tnnt2-R92W and mice carrying both pathogenic heterozygous mutations. Our results showed that mice with double heterozygous mutations exhibited significant hypertrophic cardiomyopathy phenotypes at 4 weeks of age, and the degree of hypertrophy was significantly higher than that of single heterozygous mutant mice of the same age. Our study suggests that carrying the two pathogenic heterozygous mutations simultaneously can aggravate the phenotype of HCM in mice, which provides experimental evidence for the genotype-phenotype relationship of double pathogenic mutations and provides reference significance for clinical risk stratification of HCM patients.
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Affiliation(s)
- Minjie Lu
- State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Shuai Li
- State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Ziqiang Han
- State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Bingxuan Ma
- State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Leqi Wang
- State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Fangfang Wan
- State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Song Lei
- State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China; Cardiomyopathy Ward, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China; National Clinical Research Center of Cardiovascular Diseases, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.
| | - Yu Nie
- State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.
| | - Jizheng Wang
- State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.
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Chirikian O, Faynus MA, Merk M, Singh Z, Muray C, Pham J, Chialastri A, Vander Roest A, Goldstein A, Pyle T, Lane KV, Roberts B, Smith JE, Gunawardane RN, Sniadecki NJ, Mack DL, Davis J, Bernstein D, Streichan SJ, Clegg DO, Dey SS, Wilson MZ, Pruitt BL. YAP dysregulation triggers hypertrophy by CCN2 secretion and TGFβ uptake in human pluripotent stem cell-derived cardiomyocytes. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.03.597045. [PMID: 38895282 PMCID: PMC11185505 DOI: 10.1101/2024.06.03.597045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/21/2024]
Abstract
Hypertrophy Cardiomyopathy (HCM) is the most prevalent hereditary cardiovascular disease - affecting >1:500 individuals. Advanced forms of HCM clinically present with hypercontractility, hypertrophy and fibrosis. Several single-point mutations in b-myosin heavy chain (MYH7) have been associated with HCM and increased contractility at the organ level. Different MYH7 mutations have resulted in increased, decreased, or unchanged force production at the molecular level. Yet, how these molecular kinetics link to cell and tissue pathogenesis remains unclear. The Hippo Pathway, specifically its effector molecule YAP, has been demonstrated to be reactivated in pathological hypertrophic growth. We hypothesized that changes in force production (intrinsically or extrinsically) directly alter the homeostatic mechano-signaling of the Hippo pathway through changes in stresses on the nucleus. Using human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs), we asked whether homeostatic mechanical signaling through the canonical growth regulator, YAP, is altered 1) by changes in the biomechanics of HCM mutant cardiomyocytes and 2) by alterations in the mechanical environment. We use genetically edited hiPSC-CM with point mutations in MYH7 associated with HCM, and their matched controls, combined with micropatterned traction force microscopy substrates to confirm the hypercontractile phenotype in MYH7 mutants. We next modulate contractility in healthy and disease hiPSC-CMs by treatment with positive and negative inotropic drugs and demonstrate a correlative relationship between contractility and YAP activity. We further demonstrate the activation of YAP in both HCM mutants and healthy hiPSC-CMs treated with contractility modulators is through enhanced nuclear deformation. We conclude that the overactivation of YAP, possibly initiated and driven by hypercontractility, correlates with excessive CCN2 secretion (connective tissue growth factor), enhancing cardiac fibroblast/myofibroblast transition and production of known hypertrophic signaling molecule TGFβ. Our study suggests YAP being an indirect player in the initiation of hypertrophic growth and fibrosis in HCM. Our results provide new insights into HCM progression and bring forth a testbed for therapeutic options in treating HCM.
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Janssens JV, Raaijmakers AJA, Weeks KL, Bell JR, Mellor KM, Curl CL, Delbridge LMD. The cardiomyocyte origins of diastolic dysfunction: cellular components of myocardial "stiffness". Am J Physiol Heart Circ Physiol 2024; 326:H584-H598. [PMID: 38180448 DOI: 10.1152/ajpheart.00334.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/08/2023] [Revised: 12/07/2023] [Accepted: 12/21/2023] [Indexed: 01/06/2024]
Abstract
The impaired ability of the heart to relax and stretch to accommodate venous return is generally understood to represent a state of "diastolic dysfunction" and often described using the all-purpose noun "stiffness." Despite the now common qualitative usage of this term in fields of cardiac patho/physiology, the specific quantitative concept of stiffness as a molecular and biophysical entity with real practical interpretation in healthy and diseased hearts is sometimes obscure. The focus of this review is to characterize the concept of cardiomyocyte stiffness and to develop interpretation of "stiffness" attributes at the cellular and molecular levels. Here, we consider "stiffness"-related terminology interpretation and make links between cardiomyocyte stiffness and aspects of functional and structural cardiac performance. We discuss cross bridge-derived stiffness sources, considering the contributions of diastolic myofilament activation and impaired relaxation. This includes commentary relating to the role of cardiomyocyte Ca2+ flux and Ca2+ levels in diastole, the troponin-tropomyosin complex role as a Ca2+ effector in diastole, the myosin ADP dissociation rate as a modulator of cross bridge attachment and regulation of cross-bridge attachment by myosin binding protein C. We also discuss non-cross bridge-derived stiffness sources, including the titin sarcomeric spring protein, microtubule and intermediate filaments, and cytoskeletal extracellular matrix interactions. As the prevalence of conditions involving diastolic heart failure has escalated, a more sophisticated understanding of the molecular, cellular, and tissue determinants of cardiomyocyte stiffness offers potential to develop imaging and molecular intervention tools.
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Affiliation(s)
- Johannes V Janssens
- Department of Anatomy and Physiology, University of Melbourne, Melbourne, Victoria, Australia
| | - Antonia J A Raaijmakers
- Department of Anatomy and Physiology, University of Melbourne, Melbourne, Victoria, Australia
| | - Kate L Weeks
- Department of Anatomy and Physiology, University of Melbourne, Melbourne, Victoria, Australia
- Baker Department of Cardiometabolic Health, University of Melbourne, Melbourne, Victoria, Australia
- Department of Diabetes, Monash University, Parkville, Victoria, Australia
| | - James R Bell
- Department of Anatomy and Physiology, University of Melbourne, Melbourne, Victoria, Australia
- Department of Microbiology, Anatomy, Physiology and Pharmacology, La Trobe University, Melbourne, Victoria, Australia
| | - Kimberley M Mellor
- Department of Anatomy and Physiology, University of Melbourne, Melbourne, Victoria, Australia
- Department of Physiology, University of Auckland, Auckland, New Zealand
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Claire L Curl
- Department of Anatomy and Physiology, University of Melbourne, Melbourne, Victoria, Australia
| | - Lea M D Delbridge
- Department of Anatomy and Physiology, University of Melbourne, Melbourne, Victoria, Australia
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Sun B, Kekenes-Huskey PM. Myofilament-associated proteins with intrinsic disorder (MAPIDs) and their resolution by computational modeling. Q Rev Biophys 2023; 56:e2. [PMID: 36628457 PMCID: PMC11070111 DOI: 10.1017/s003358352300001x] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The cardiac sarcomere is a cellular structure in the heart that enables muscle cells to contract. Dozens of proteins belong to the cardiac sarcomere, which work in tandem to generate force and adapt to demands on cardiac output. Intriguingly, the majority of these proteins have significant intrinsic disorder that contributes to their functions, yet the biophysics of these intrinsically disordered regions (IDRs) have been characterized in limited detail. In this review, we first enumerate these myofilament-associated proteins with intrinsic disorder (MAPIDs) and recent biophysical studies to characterize their IDRs. We secondly summarize the biophysics governing IDR properties and the state-of-the-art in computational tools toward MAPID identification and characterization of their conformation ensembles. We conclude with an overview of future computational approaches toward broadening the understanding of intrinsic disorder in the cardiac sarcomere.
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Affiliation(s)
- Bin Sun
- Research Center for Pharmacoinformatics (The State-Province Key Laboratories of Biomedicine-Pharmaceutics of China), Department of Medicinal Chemistry and Natural Medicine Chemistry, College of Pharmacy, Harbin Medical University, Harbin 150081, China
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Kaviarasan V, Mohammed V, Veerabathiran R. Genetic predisposition study of heart failure and its association with cardiomyopathy. Egypt Heart J 2022; 74:5. [PMID: 35061126 PMCID: PMC8782994 DOI: 10.1186/s43044-022-00240-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2021] [Accepted: 01/12/2022] [Indexed: 12/12/2022] Open
Abstract
Heart failure (HF) is a clinical condition distinguished by structural and functional defects in the myocardium, which genetic and environmental factors can induce. HF is caused by various genetic factors that are both heterogeneous and complex. The incidence of HF varies depending on the definition and area, but it is calculated to be between 1 and 2% in developed countries. There are several factors associated with the progression of HF, ranging from coronary artery disease to hypertension, of which observed the most common genetic cause to be cardiomyopathy. The main objective of this study is to investigate heart failure and its association with cardiomyopathy with their genetic variants. The selected novel genes that have been linked to human inherited cardiomyopathy play a critical role in the pathogenesis and progression of HF. Research sources collected from the human gene mutation and several databases revealed that numerous genes are linked to cardiomyopathy and thus explained the hereditary influence of such a condition. Our findings support the understanding of the genetics aspect of HF and will provide more accurate evidence of the role of changing disease accuracy. Furthermore, a better knowledge of the molecular pathophysiology of genetically caused HF could contribute to the emergence of personalized therapeutics in future.
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Affiliation(s)
- Vaishak Kaviarasan
- Human Cytogenetics and Genomics Laboratory, Faculty of Allied Health Sciences, Chettinad Hospital and Research Institute, Chettinad Academy of Research and Education, Kelambakkam, Tamilnadu, 603103, India
| | - Vajagathali Mohammed
- Human Cytogenetics and Genomics Laboratory, Faculty of Allied Health Sciences, Chettinad Hospital and Research Institute, Chettinad Academy of Research and Education, Kelambakkam, Tamilnadu, 603103, India
| | - Ramakrishnan Veerabathiran
- Human Cytogenetics and Genomics Laboratory, Faculty of Allied Health Sciences, Chettinad Hospital and Research Institute, Chettinad Academy of Research and Education, Kelambakkam, Tamilnadu, 603103, India.
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Angelini A, Gorey MA, Dumont F, Mougenot N, Chatzifrangkeskou M, Muchir A, Li Z, Mericskay M, Decaux JF. Cardioprotective effects of α-cardiac actin on oxidative stress in a dilated cardiomyopathy mouse model. FASEB J 2019; 34:2987-3005. [PMID: 31908029 DOI: 10.1096/fj.201902389r] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Revised: 12/12/2019] [Accepted: 12/15/2019] [Indexed: 12/12/2022]
Abstract
The expression of α-cardiac actin, a major constituent of the cytoskeleton of cardiomyocytes, is dramatically decreased in a mouse model of dilated cardiomyopathy triggered by inducible cardiac-specific serum response factor (Srf) gene disruption that could mimic some forms of human dilated cardiomyopathy. To investigate the consequences of the maintenance of α-cardiac actin expression in this model, we developed a new transgenic mouse based on Cre/LoxP strategy, allowing together the induction of SRF loss and a compensatory expression of α-cardiac actin. Here, we report that maintenance of α-cardiac actin within cardiomyocytes temporally preserved cytoarchitecture from adverse cardiac remodeling through a positive impact on both structural and transcriptional levels. These protective effects were accompanied in vivo by the decrease of ROS generation and protein carbonylation and the downregulation of NADPH oxidases NOX2 and NOX4. We also show that ectopic expression of α-cardiac actin protects HEK293 cells against oxidative stress induced by H2 O2 . Oxidative stress plays an important role in the development of cardiac remodeling and contributes also to the pathogenesis of heart failure. Taken together, these findings indicate that α-cardiac actin could be involved in the regulation of oxidative stress that is a leading cause of adverse remodeling during dilated cardiomyopathy development.
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Affiliation(s)
- Aude Angelini
- Biological Adaptation and Ageing, Institut de Biologie Paris-Seine (IBPS), CNRS UMR 8256, INSERM ERL U1164, Sorbonne Université, Paris, France
| | - Mark-Alexander Gorey
- Biological Adaptation and Ageing, Institut de Biologie Paris-Seine (IBPS), CNRS UMR 8256, INSERM ERL U1164, Sorbonne Université, Paris, France
| | - Florent Dumont
- Signalling and Cardiovascular Pathophysiology, INSERM UMR-S 1180, Université Paris-Saclay, Châtenay-Malabry, France
| | - Nathalie Mougenot
- Faculté de Médecine, Pierre et Marie Curie, INSERM UMS 28 Phénotypage du petit animal, Sorbonne Université, Paris, France
| | - Maria Chatzifrangkeskou
- Center of Research in Myology, Institut de Myologie, INSERM UMRS 974, Sorbonne Université, Paris, France
| | - Antoine Muchir
- Center of Research in Myology, Institut de Myologie, INSERM UMRS 974, Sorbonne Université, Paris, France
| | - Zhenlin Li
- Biological Adaptation and Ageing, Institut de Biologie Paris-Seine (IBPS), CNRS UMR 8256, INSERM ERL U1164, Sorbonne Université, Paris, France
| | - Mathias Mericskay
- Signalling and Cardiovascular Pathophysiology, INSERM UMR-S 1180, Université Paris-Saclay, Châtenay-Malabry, France
| | - Jean-Francois Decaux
- Biological Adaptation and Ageing, Institut de Biologie Paris-Seine (IBPS), CNRS UMR 8256, INSERM ERL U1164, Sorbonne Université, Paris, France
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Neagoe O, Ciobanu A, Diaconu R, Mirea O, Donoiu I, Militaru C. A rare case of familial restrictive cardiomyopathy, with mutations in MYH7 and ABCC9 genes. Discoveries (Craiova) 2019; 7:e99. [PMID: 32309617 PMCID: PMC7086075 DOI: 10.15190/d.2019.12] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Restrictive cardiomyopathy is the least common type of cardiomyopathy, being defined by diastolic dysfunction and often unimpaired systolic function. Restrictive cardiomyopathies can be classified as familial or non-familial. Patients with familial restrictive cardiomyopathy can develop signs and symptoms of this condition anytime from childhood to adulthood. The evolution of the disease is towards signs and symptoms of pulmonary and systemic congestion and, without treatment, there is a five-year mortality rate of approximately 30% in these patients. We discuss the case of a 43-year-old patient diagnosed with familial restrictive cardiomyopathy with positive genetic tests for mutations of MYH7 gene and ABCC9 gene, who was first hospitalized in 2011 for palpitations. The echocardiography performed in evolution showed a continuous alteration of right ventricle function, without important differences of left ventricular function. She developed heart failure symptoms six years after diagnosis and she had seven hospitalizations in the past two years, currently with an increasing need of diuretics and persistent hepatic dysfunction. Cardiac transplantation or left ventricular assist device therapy should be considered in patients with severe heart failure symptoms and no longer effective treatment. However, elevated pulmonary vascular resistance excludes the patient from cardiac transplantation.
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Affiliation(s)
- Oana Neagoe
- Department of Cardiology, Emergency County Hospital, Craiova, Romania
| | - Anda Ciobanu
- Department of Cardiology, Emergency County Hospital, Craiova, Romania
| | - Rodica Diaconu
- Department of Cardiology, Emergency County Hospital, Craiova, Romania
| | - Oana Mirea
- Department of Cardiology, University of Medicine and Pharmacy of Craiova, Romania
| | - Ionuț Donoiu
- Department of Cardiology, University of Medicine and Pharmacy of Craiova, Romania
| | - Constantin Militaru
- Department of Cardiology, University of Medicine and Pharmacy of Craiova, Romania
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Precone V, Krasi G, Guerri G, Madureri A, Piazzani M, Michelini S, Barati S, Maniscalchi T, Bressan S, Bertelli M. Cardiomyopathies. ACTA BIO-MEDICA : ATENEI PARMENSIS 2019; 90:32-43. [PMID: 31577251 PMCID: PMC7233648 DOI: 10.23750/abm.v90i10-s.8755] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Accepted: 08/05/2019] [Indexed: 01/17/2023]
Abstract
The most common cardiomyopathies often present to primary care physicians with similar symptoms, despite the fact that they involve a variety of phenotypes and etiologies (1). Many have signs and symptoms common in heart failure, such as reduced ejection fraction, peripheral edema, fatigue, orthopnea, exertion dyspnea, paroxysmal nocturnal dyspnea, presyncope, syncope and cardiac ischemia (1). In all cardiomyopathies, the cardiac muscle (myocardium) may be structurally and/or functionally impaired. They can be classified as hypertrophic, dilated, left-ventricular non compaction, restrictive and arrhythmogenic right ventricular cardiomyopathies. (www.actabiomedica.it)
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Reda SM, Chandra M. Dilated cardiomyopathy mutation (R174W) in troponin T attenuates the length-mediated increase in cross-bridge recruitment and myofilament Ca 2+ sensitivity. Am J Physiol Heart Circ Physiol 2019; 317:H648-H657. [PMID: 31373515 DOI: 10.1152/ajpheart.00171.2019] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Alterations in length-dependent activation (LDA) may constitute a mechanism by which cardiomyopathy mutations lead to deleterious phenotypes and compromised heart function, because LDA underlies the molecular basis by which the heart tunes myocardial force production on a beat-to-beat basis (Frank-Starling mechanism). In this study, we investigated the effect of DCM-linked mutation (R173W) in human cardiac troponin T (TnT) on myofilament LDA. R173W mutation is associated with left ventricular dilatation and systolic dysfunction and is found in multiple families. R173W mutation is in the central region (residues 80-180) of TnT, which is known to be important for myofilament cooperativity and cross-bridge (XB) recruitment. Steady-state and dynamic contractile parameters were measured in detergent-skinned guinea pig left ventricular muscle fibers reconstituted with recombinant guinea pig wild-type TnT (TnTWT) or mutant TnT (TnTR174W; guinea pig analog of human R173W mutation) at two different sarcomere lengths (SL): short (1.9 µm) and long (2.3 µm). TnTR174W decreased pCa50 (-log [Ca2+]free required for half-maximal activation) to a greater extent at long than at short SL; for example, pCa50 decreased by 0.12 pCa units at long SL and by 0.06 pCa units at short SL. Differential changes in pCa50 at short and long SL attenuated the SL-dependent increase in myofilament Ca2+ sensitivity (ΔpCa50) in TnTR174W fibers; ΔpCa50 was 0.10 units in TnTWT fibers but only 0.04 units in TnTR174W fibers. Furthermore, TnTR174W blunted the SL-dependent increase in the magnitude of XB recruitment. Our observations suggest that the R173W mutation in human cardiac TnT may impair Frank-Starling mechanism.NEW & NOTEWORTHY This work characterizes the effect of dilated cardiomyopathy mutation in cardiac troponin T (TnTR174W) on myofilament length-dependent activation. TnTR174W attenuates the length-dependent increase in cross-bridge recruitment and myofilament Ca2+ sensitivity.
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Affiliation(s)
- Sherif M Reda
- Department of Integrative Physiology and Neuroscience, Washington State University, Pullman, Washington
| | - Murali Chandra
- Department of Integrative Physiology and Neuroscience, Washington State University, Pullman, Washington
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10
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Carrillo-Salinas FJ, Ngwenyama N, Anastasiou M, Kaur K, Alcaide P. Heart Inflammation: Immune Cell Roles and Roads to the Heart. THE AMERICAN JOURNAL OF PATHOLOGY 2019; 189:1482-1494. [PMID: 31108102 DOI: 10.1016/j.ajpath.2019.04.009] [Citation(s) in RCA: 72] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Revised: 03/29/2019] [Accepted: 04/18/2019] [Indexed: 02/08/2023]
Abstract
Heart failure (HF) has been traditionally viewed as a disease of the cardiac muscle associated with systemic inflammation. Burgeoning evidence implicates immune effector mechanisms that include immune cell activation and trafficking to the heart. Immune cell infiltration in the myocardium can have adverse effects in the heart and contribute to the pathogenesis of HF. Both innate and adaptive immunity operate sequentially, and the specificity of these responses depends on the initial trigger sensed by the heart. Although the role of the immune system in the initial inflammatory response to infection and injury is well studied, what sets the trajectory to HF from different etiologies and the role of immunity once HF has been established is less understood. Herein, we review experimental and clinical knowledge of cardiac inflammation induced by different triggers that often result in HF from different etiologies. We focus on the mechanisms of immune cell activation systemically and on the pathways immune cells use to traffic to the heart.
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Affiliation(s)
| | - Njabulo Ngwenyama
- Department of Immunology, Tufts University School of Medicine, Boston, Massachusetts; Sackler School for Graduate Studies Immunology Program, Tufts University School of Medicine, Boston, Massachusetts
| | - Marina Anastasiou
- Department of Immunology, Tufts University School of Medicine, Boston, Massachusetts
| | - Kuljeet Kaur
- Department of Immunology, Tufts University School of Medicine, Boston, Massachusetts
| | - Pilar Alcaide
- Department of Immunology, Tufts University School of Medicine, Boston, Massachusetts; Sackler School for Graduate Studies Immunology Program, Tufts University School of Medicine, Boston, Massachusetts.
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11
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Spudich JA. Three perspectives on the molecular basis of hypercontractility caused by hypertrophic cardiomyopathy mutations. Pflugers Arch 2019; 471:701-717. [PMID: 30767072 PMCID: PMC6475635 DOI: 10.1007/s00424-019-02259-2] [Citation(s) in RCA: 104] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Revised: 01/11/2019] [Accepted: 01/20/2019] [Indexed: 01/10/2023]
Abstract
Several lines of evidence suggest that the primary effect of hypertrophic cardiomyopathy mutations in human β-cardiac myosin is hypercontractility of the heart, which leads to subsequent hypertrophy, fibrosis, and myofilament disarray. Here, I describe three perspectives on the molecular basis of this hypercontractility. The first is that hypercontractility results from changes in the fundamental parameters of the actin-activated β-cardiac myosin chemo-mechanical ATPase cycle. The second considers that hypercontractility results from an increase in the number of functionally accessible heads in the sarcomere for interaction with actin. The final and third perspective is that load dependence of contractility is affected by cardiomyopathy mutations and small-molecule effectors in a manner that changes the power output of cardiac contraction. Experimental approaches associated with each perspective are described along with concepts of therapeutic approaches that could prove valuable in treating hypertrophic cardiomyopathy.
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Affiliation(s)
- James A Spudich
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA, 94305, USA.
- Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA, 94305, USA.
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12
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Bunch TA, Lepak VC, Kanassatega RS, Colson BA. N-terminal extension in cardiac myosin-binding protein C regulates myofilament binding. J Mol Cell Cardiol 2018; 125:140-148. [PMID: 30359561 DOI: 10.1016/j.yjmcc.2018.10.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Revised: 08/22/2018] [Accepted: 10/10/2018] [Indexed: 10/28/2022]
Abstract
RATIONALE Mutations in the gene encoding the sarcomeric protein cardiac myosin-binding protein C (cMyBP-C) are a leading cause of hypertrophic cardiomyopathy (HCM). Mouse models targeting cMyBP-C and use of recombinant proteins have been effective in studying its roles in contractile function and disease. Surprisingly, while the N-terminus of cMyBP-C is important to regulate myofilament binding and contains many HCM mutations, an incorrect sequence, lacking the N-terminal 8 amino acids has been used in many studies. OBJECTIVES To determine the N-terminal cMyBP-C sequences in ventricles and investigate the roles of species-specific differences in cMyBP-C on myofilament binding. METHODS AND RESULTS We determined cMyBP-C sequences in mouse and human by inspecting available sequence databases. N-terminal differences were confirmed using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Cosedimentation assays with actin or myosin were used to examine binding in mouse, human and chimeric fusion proteins of cMyBP-C. Time-resolved FRET (TR-FRET) with site-directed probes on cMyBP-C was employed to measure structural dynamics. LC-MS/MS supported the sequencing data that mouse cMyBP-C contains an eight-residue N-terminal extension (NTE) not found in human. Cosedimentation assays revealed that cardiac myosin binding was strongly influenced by the presence of the NTE, which reduced binding by 60%. 75% more human C0-C2 than mouse bound to myosin. Actin binding of mouse C0-C2 was not affected by the NTE. 50% more human C0-C2 than mouse bound to actin. TR-FRET indicates that the NTE did not significantly affect structural dynamics across domains C0 and C1. CONCLUSIONS Our functional results are consistent with the idea that cardiac myosin binding of N-terminal cMyBP-C is reduced in the mouse protein due to the presence of the NTE, which is proposed to interfere with myosin regulatory light chain (RLC) binding. The NTE is a critical component of mouse cMyBP-C, and should be considered in extrapolation of studies to cMyBP-C and HCM mechanisms in human.
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Affiliation(s)
- Thomas A Bunch
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85724, United States
| | - Victoria C Lepak
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85724, United States
| | - Rhye-Samuel Kanassatega
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85724, United States
| | - Brett A Colson
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85724, United States.
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Prestes PR, Marques FZ, Lopez-Campos G, Lewandowski P, Delbridge LMD, Charchar FJ, Harrap SB. Involvement of human monogenic cardiomyopathy genes in experimental polygenic cardiac hypertrophy. Physiol Genomics 2018; 50:680-687. [PMID: 29775428 DOI: 10.1152/physiolgenomics.00143.2017] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Hypertrophic cardiomyopathy thickens heart muscles, reducing functionality and increasing risk of cardiac disease and morbidity. Genetic factors are involved, but their contribution is poorly understood. We used the hypertrophic heart rat (HHR), a unique normotensive polygenic model of cardiac hypertrophy and heart failure, to investigate the role of genes associated with monogenic human cardiomyopathy. We selected 42 genes involved in monogenic human cardiomyopathies to study: 1) DNA variants, by sequencing the whole genome of 13-wk-old HHR and age-matched normal heart rat (NHR), its genetic control strain; 2) mRNA expression, by targeted RNA-sequencing in left ventricles of HHR and NHR at 5 ages (2 days old and 4, 13, 33, and 50 wk old) compared with human idiopathic dilated cardiomyopathy data; and 3) microRNA expression, with rat microRNA microarrays in left ventricles of 2-day-old HHR and age-matched NHR. We also investigated experimentally validated microRNA-mRNA interactions. Whole-genome sequencing revealed unique variants mostly located in noncoding regions of HHR and NHR. We found 29 genes differentially expressed in at least 1 age. Genes encoding desmoglein 2 ( Dsg2) and transthyretin ( Ttr) were significantly differentially expressed at all ages in the HHR, but only Ttr was also differentially expressed in human idiopathic cardiomyopathy. Lastly, only two microRNAs differentially expressed in the HHR were present in our comparison of validated microRNA-mRNA interactions. These two microRNAs interact with five of the genes studied. Our study shows that genes involved in monogenic forms of human cardiomyopathies may also influence polygenic forms of the disease.
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Affiliation(s)
- P R Prestes
- School of Applied and Biomedical Sciences, Faculty of Science and Technology, Federation University Australia , Ballarat, Victoria , Australia
| | - F Z Marques
- School of Applied and Biomedical Sciences, Faculty of Science and Technology, Federation University Australia , Ballarat, Victoria , Australia.,Heart Failure Research Laboratory, Baker Heart and Diabetes Research Institute , Melbourne, Victoria , Australia
| | - G Lopez-Campos
- Wellcome-Wolfson Institute for Experimental Medicine, Queen's University of Belfast , Belfast , United Kingdom.,Health and Biomedical Informatics Centre, University of Melbourne , Melbourne, Victoria , Australia
| | - P Lewandowski
- School of Medicine, Deakin University , Geelong, Victoria , Australia
| | - L M D Delbridge
- Department of Physiology, University of Melbourne , Melbourne, Victoria , Australia
| | - F J Charchar
- School of Applied and Biomedical Sciences, Faculty of Science and Technology, Federation University Australia , Ballarat, Victoria , Australia
| | - S B Harrap
- Department of Physiology, University of Melbourne , Melbourne, Victoria , Australia
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14
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Wang L, Geist J, Grogan A, Hu LYR, Kontrogianni-Konstantopoulos A. Thick Filament Protein Network, Functions, and Disease Association. Compr Physiol 2018; 8:631-709. [PMID: 29687901 PMCID: PMC6404781 DOI: 10.1002/cphy.c170023] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Sarcomeres consist of highly ordered arrays of thick myosin and thin actin filaments along with accessory proteins. Thick filaments occupy the center of sarcomeres where they partially overlap with thin filaments. The sliding of thick filaments past thin filaments is a highly regulated process that occurs in an ATP-dependent manner driving muscle contraction. In addition to myosin that makes up the backbone of the thick filament, four other proteins which are intimately bound to the thick filament, myosin binding protein-C, titin, myomesin, and obscurin play important structural and regulatory roles. Consistent with this, mutations in the respective genes have been associated with idiopathic and congenital forms of skeletal and cardiac myopathies. In this review, we aim to summarize our current knowledge on the molecular structure, subcellular localization, interacting partners, function, modulation via posttranslational modifications, and disease involvement of these five major proteins that comprise the thick filament of striated muscle cells. © 2018 American Physiological Society. Compr Physiol 8:631-709, 2018.
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Affiliation(s)
- Li Wang
- Department of Biochemistry and Molecular Biology, University of Maryland, Baltimore, Maryland, USA
| | - Janelle Geist
- Department of Biochemistry and Molecular Biology, University of Maryland, Baltimore, Maryland, USA
| | - Alyssa Grogan
- Department of Biochemistry and Molecular Biology, University of Maryland, Baltimore, Maryland, USA
| | - Li-Yen R. Hu
- Department of Biochemistry and Molecular Biology, University of Maryland, Baltimore, Maryland, USA
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15
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Zhou N, Qin S, Liu Y, Tang L, Zhao W, Pan C, Qiu Z, Wang X, Shu X. Whole-exome sequencing identifies rare compound heterozygous mutations in the MYBPC3 gene associated with severe familial hypertrophic cardiomyopathy. Eur J Med Genet 2018. [PMID: 29524613 DOI: 10.1016/j.ejmg.2018.03.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Most patients with hypertrophic cardiomyopathy have single-gene autosomal dominant mutations in loci that encode for sarcomeric proteins. The aim of this study was to determine whether pathogenic mutations were present by whole-exome sequencing (WES) in two families with hypertrophic cardiomyopathy (HCM) that presented during adolescence. Blood samples and clinical data were collected from individuals in two families with HCM. DNA was extracted. Mutations were identified using whole-exome sequencing (WES), and the genotypes of family members were identified using Sanger sequencing. Compound heterozygous mutations in the MYBPC3 gene (c.659A > G, p.Tyr220Cys; c.772G > A, p.Glu258Lys,NM_000256, Family 1), (c.873delG, p. Ile292PhefsTer8; c.3G > A, p.Met1?, NM_000256, Family 2) were identified by WES. Patient 1 carried the maternally inherited c.659A > G mutation and the paternally inherited c.772G > A mutation. Patient 2 carried the maternally inherited frameshift mutation c.873delG and the paternally inherited mutation c.3G > A. Two families with HCM presenting during adolescence (age of onset is about 11 years old) demonstrated compound heterozygous mutations in the MYBPC3 gene. These findings suggested an association of MYBPC3 mutations with the early onset of symptoms and worsened prognoses. Our study highlights the importance of genetic screening of all family members in cases of HCM.
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Affiliation(s)
- Nianwei Zhou
- Department of Echocardiography, Zhongshan Hospital, Fudan University, Shanghai Institute of Cardiovascular Disease, Shanghai Institute of Medical Imaging, 200032 Shanghai, China
| | - Shengmei Qin
- Department of Cardiology, Zhongshan Hospital, Fudan University, Shanghai Institute of Cardiovascular Disease, Shanghai Institute of Medical Imaging, 200032 Shanghai, China
| | - Yili Liu
- Department of Clinical Laboratory, Tongji Hospital, Tongji Univesity, 200032 Shanghai, China
| | - Lu Tang
- Department of Echocardiography, Zhongshan Hospital, Fudan University, Shanghai Institute of Cardiovascular Disease, Shanghai Institute of Medical Imaging, 200032 Shanghai, China
| | - Weipeng Zhao
- Department of Echocardiography, Zhongshan Hospital, Fudan University, Shanghai Institute of Cardiovascular Disease, Shanghai Institute of Medical Imaging, 200032 Shanghai, China
| | - Cuizhen Pan
- Department of Echocardiography, Zhongshan Hospital, Fudan University, Shanghai Institute of Cardiovascular Disease, Shanghai Institute of Medical Imaging, 200032 Shanghai, China
| | - Zilong Qiu
- Institute of Neuroscience, State Kay Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, China.
| | - Xiaolin Wang
- Department of Interventional Radiology, Zhongshan Hospital, Fudan University, Shanghai Institute of Medical Imaging, 200032 Shanghai, China.
| | - Xianhong Shu
- Department of Echocardiography, Zhongshan Hospital, Fudan University, Shanghai Institute of Cardiovascular Disease, Shanghai Institute of Medical Imaging, 200032 Shanghai, China.
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16
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MYBPC3 mutations are associated with a reduced super-relaxed state in patients with hypertrophic cardiomyopathy. PLoS One 2017; 12:e0180064. [PMID: 28658286 PMCID: PMC5489194 DOI: 10.1371/journal.pone.0180064] [Citation(s) in RCA: 87] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2017] [Accepted: 06/08/2017] [Indexed: 11/23/2022] Open
Abstract
The “super-relaxed state” (SRX) of myosin represents a ‘reserve’ of motors in the heart. Myosin heads in the SRX are bound to the thick filament and have a very low ATPase rate. Changes in the SRX are likely to modulate cardiac contractility. We previously demonstrated that the SRX is significantly reduced in mouse cardiomyocytes lacking cardiac myosin binding protein–C (cMyBP-C). Here, we report the effect of mutations in the cMyBP-C gene (MYBPC3) using samples from human patients with hypertrophic cardiomyopathy (HCM). Left ventricular (LV) samples from 11 HCM patients were obtained following myectomy surgery to relieve LV outflow tract obstruction. HCM samples were genotyped as either MYBPC3 mutation positive (MYBPC3mut) or negative (HCMsmn) and were compared to eight non-failing donor hearts. Compared to donors, only MYBPC3mut samples display a significantly diminished SRX, characterised by a decrease in both the number of myosin heads in the SRX and the lifetime of ATP turnover. These changes were not observed in HCMsmn samples. There was a positive correlation (p < 0.01) between the expression of cMyBP-C and the proportion of myosin heads in the SRX state, suggesting cMyBP-C modulates and maintains the SRX. Phosphorylation of the myosin regulatory light chain in MYBPC3mut samples was significantly decreased compared to the other groups, suggesting a potential mechanism to compensate for the diminished SRX. We conclude that by altering both contractility and sarcomeric energy requirements, a reduced SRX may be an important disease mechanism in patients with MYBPC3 mutations.
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17
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Ren X, Hensley N, Brady MB, Gao WD. The Genetic and Molecular Bases for Hypertrophic Cardiomyopathy: The Role for Calcium Sensitization. J Cardiothorac Vasc Anesth 2017; 32:478-487. [PMID: 29203298 DOI: 10.1053/j.jvca.2017.05.035] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Indexed: 11/11/2022]
Abstract
Hypertrophic cardiomyopathy (HCM) affects millions of people around the world as one of the most common genetic heart disorders and leads to cardiac ischemia, heart failure, dysfunction of other organ systems, and increased risk for sudden unexpected cardiac deaths. HCM can be caused by single-point mutations, insertion or deletion mutations, or truncation of cardiac myofilament proteins. The molecular mechanism that leads to disease progression and presentation is still poorly understood, despite decades of investigations. However, recent research has made dramatic advances in the understanding of HCM disease development. Studies have shown that increased calcium sensitivity is a universal feature in HCM. At the molecular level, increased crossbridge force (or power) generation resulting in hypercontractility is the prominent feature. Thus, calcium sensitization/hypercontractility is emerging as the primary stimulus for HCM disease development and phenotypic expression. Cross-bridge inhibition has been shown to halt HCM presentation, and myofilament desensitization appears to reduce lethal arrhythmias in animal models of HCM. These advances in basic research will continue to deepen the knowledge of HCM pathogenesis and are beginning to revolutionize the management of HCM.
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Affiliation(s)
- Xianfeng Ren
- Department of Anesthesiology, China-Japan Friendship Hospital, Beijing, China
| | - Nadia Hensley
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD
| | - Mary Beth Brady
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD
| | - Wei Dong Gao
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD.
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18
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Tang W, Blair CA, Walton SD, Málnási-Csizmadia A, Campbell KS, Yengo CM. Modulating Beta-Cardiac Myosin Function at the Molecular and Tissue Levels. Front Physiol 2017; 7:659. [PMID: 28119616 PMCID: PMC5220080 DOI: 10.3389/fphys.2016.00659] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Accepted: 12/15/2016] [Indexed: 01/10/2023] Open
Abstract
Inherited cardiomyopathies are a common form of heart disease that are caused by mutations in sarcomeric proteins with beta cardiac myosin (MYH7) being one of the most frequently affected genes. Since the discovery of the first cardiomyopathy associated mutation in beta-cardiac myosin, a major goal has been to correlate the in vitro myosin motor properties with the contractile performance of cardiac muscle. There has been substantial progress in developing assays to measure the force and velocity properties of purified cardiac muscle myosin but it is still challenging to correlate results from molecular and tissue-level experiments. Mutations that cause hypertrophic cardiomyopathy are more common than mutations that lead to dilated cardiomyopathy and are also often associated with increased isometric force and hyper-contractility. Therefore, the development of drugs designed to decrease isometric force by reducing the duty ratio (the proportion of time myosin spends bound to actin during its ATPase cycle) has been proposed for the treatment of hypertrophic cardiomyopathy. Para-Nitroblebbistatin is a small molecule drug proposed to decrease the duty ratio of class II myosins. We examined the impact of this drug on human beta cardiac myosin using purified myosin motor assays and studies of permeabilized muscle fiber mechanics. We find that with purified human beta-cardiac myosin para-Nitroblebbistatin slows actin-activated ATPase and in vitro motility without altering the ADP release rate constant. In permeabilized human myocardium, para-Nitroblebbistatin reduces isometric force, power, and calcium sensitivity while not changing shortening velocity or the rate of force development (ktr). Therefore, designing a drug that reduces the myosin duty ratio by inhibiting strong attachment to actin while not changing detachment can cause a reduction in force without changing shortening velocity or relaxation.
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Affiliation(s)
- Wanjian Tang
- Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine Hershey, PA, USA
| | - Cheavar A Blair
- Department of Physiology, University of Kentucky Lexington, KY, USA
| | - Shane D Walton
- Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine Hershey, PA, USA
| | | | - Kenneth S Campbell
- Department of Physiology, University of KentuckyLexington, KY, USA; Division of Cardiovascular Medicine, University of KentuckyLexington, KY, USA
| | - Christopher M Yengo
- Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine Hershey, PA, USA
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19
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L71F mutation in rat cardiac troponin T augments crossbridge recruitment and detachment dynamics against α-myosin heavy chain, but not against β-myosin heavy chain. J Muscle Res Cell Motil 2016; 37:215-223. [PMID: 27975185 DOI: 10.1007/s10974-016-9460-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2016] [Accepted: 11/23/2016] [Indexed: 10/20/2022]
Abstract
The N-terminal extension of human cardiac troponin T (TnT), which modulates myofilament Ca2+ sensitivity, contains several hypertrophic cardiomyopathy (HCM)-causing mutations including S69F. However, the functional consequence of S69F mutation is unknown. The human analog of S69F in rat TnT is L71F (TnTL71F). Because the functional consequences due to structural changes in the N-terminal extension are influenced by the type of myosin heavy chain (MHC) isoform, we hypothesized that the TnTL71F-mediated effect would be differently modulated by α- and β-MHC isoforms. TnTL71F and wild-type rat TnT were reconstituted into de-membranated muscle fibers from normal (α-MHC) and propylthiouracil-treated rat hearts (β-MHC) to measure steady-state and dynamic contractile parameters. The magnitude of the TnTL71F-mediated attenuation of Ca2+-activated maximal tension was greater in α- than in β-MHC fibers. For example, TnTL71F attenuated maximal tension by 31% in α-MHC fibers but only by 10% in β-MHC fibers. Furthermore, TnTL71F reduced myofilament Ca2+ sensitivity by 0.11 pCa units in α-MHC fibers but only by 0.05 pCa units in β-MHC fibers. TnTL71F augmented rate constants of crossbridge recruitment and crossbridge detachment dynamics in α-MHC fibers but not in β-MHC fibers. Collectively, our data demonstrate that TnTL71F induces greater contractile deficits against α-MHC than against β-MHC background.
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20
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Prognostic predictive value of gene mutations in Japanese patients with hypertrophic cardiomyopathy. Heart Vessels 2016; 32:700-707. [PMID: 27885498 DOI: 10.1007/s00380-016-0920-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Accepted: 11/11/2016] [Indexed: 01/08/2023]
Abstract
Although some studies have attempted to find useful prognostic factors in hypertrophic cardiomyopathy (HCM), those results are not fully helpful for use in actual clinical practice. Furthermore, several genetic abnormalities associated with HCM have been identified. However, the genotype-phenotype correlation in HCM remains to be elucidated. Here, we attempted to assess patients with different types of gene mutations causing HCM and investigate the prognosis. A total of 140 patients with HCM underwent a screening test for myofilament gene mutations by direct sequencing of eight sarcomeric genes. Patients with a single mutation in cardiac troponin T, cardiac troponin I, α-tropomyosin, and regulatory and essential light chains were excluded from the study because the number of cases was too small. The clinical presentations and outcomes of the remaining 127 patients with HCM, 31 β-myosin heavy chain (MYH7) mutation carriers, 19 cardiac myosin-binding protein C (MYBPC3) mutation carriers, and 77 mutation non-carriers were analyzed retrospectively. MYBPC3 mutation carriers had a high frequency of ventricular arrhythmia and syncope. Kaplan-Meier curves revealed no significant difference in prognosis among the three groups, but a lack of family history of sudden death (SD) and a past history of syncope were significantly related to poor prognosis. An absence of family history of SD and past history of syncope are useful prognostic factors in patients with HCM. MYH7 and MYBPC3 mutations did not significantly influence prognosis compared to non-carriers. However, patients with the MYBPC3 mutation should be closely followed for the possibility of SD.
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21
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Nguyen S, Siu R, Dewey S, Cui Z, Gomes AV. Amino Acid Changes at Arginine 204 of Troponin I Result in Increased Calcium Sensitivity of Force Development. Front Physiol 2016; 7:520. [PMID: 27895589 PMCID: PMC5108889 DOI: 10.3389/fphys.2016.00520] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Accepted: 10/20/2016] [Indexed: 11/26/2022] Open
Abstract
Mutations in human cardiac troponin I (cTnI) have been associated with restrictive, dilated, and hypertrophic cardiomyopathies. The most commonly occurring residue on cTnI associated with familial hypertrophic cardiomyopathy (FHC) is arginine (R), which is also the most common residue at which multiple mutations occur. Two FHC mutations are known to occur at cTnI arginine 204, R204C and R204H, and both are associated with poor clinical prognosis. The R204H mutation has also been associated with restrictive cardiomyopathy (RCM). To characterize the effects of different mutations at the same residue (R204) on the physiological function of cTnI, six mutations at R204 (C, G, H, P, Q, W) were investigated in skinned fiber studies. Skinned fiber studies showed that all tested mutations at R204 caused significant increases in Ca2+ sensitivity of force development (ΔpCa50 = 0.22–0.35) when compared to wild-type (WT) cTnI. Investigation of the interactions between the cTnI mutants and WT cardiac troponin C (cTnC) or WT cardiac troponin T (cTnT) showed that all the mutations investigated, except R204G, affected either or both cTnI:cTnT and cTnI:cTnC interactions. The R204H mutation affected both cTnI:cTnT and cTnI:cTnC interactions while the R204C mutation affected only the cTnI:cTnC interaction. These results suggest that different mutations at the same site on cTnI could have varying effects on thin filament interactions. A mutation in fast skeletal TnI (R174Q, homologous to cTnI R204Q) also significantly increased Ca2+ sensitivity of force development (ΔpCa50 = 0.16). Our studies indicate that known cTnI mutations associated with poor prognosis (R204C and R204H) exhibit large increases in Ca2+ sensitivity of force development. Therefore, other R204 mutations that cause similar increases in Ca2+ sensitivity are also likely to have poor prognoses.
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Affiliation(s)
- Susan Nguyen
- Department of Neurobiology, Physiology, and Behavior, University of California, Davis Davis, CA, USA
| | - Rylie Siu
- Department of Neurobiology, Physiology, and Behavior, University of California, Davis Davis, CA, USA
| | - Shannamar Dewey
- Department of Neurobiology, Physiology, and Behavior, University of California, Davis Davis, CA, USA
| | - Ziyou Cui
- Department of Neurobiology, Physiology, and Behavior, University of California, Davis Davis, CA, USA
| | - Aldrin V Gomes
- Department of Neurobiology, Physiology, and Behavior, University of California, DavisDavis, CA, USA; Department of Physiology and Membrane Biology, University of California, DavisDavis, CA, USA
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22
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Gilda JE, Xu Q, Martinez ME, Nguyen ST, Chase PB, Gomes AV. The functional significance of the last 5 residues of the C-terminus of cardiac troponin I. Arch Biochem Biophys 2016; 601:88-96. [PMID: 26919894 PMCID: PMC4899223 DOI: 10.1016/j.abb.2016.02.023] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Revised: 02/06/2016] [Accepted: 02/22/2016] [Indexed: 11/15/2022]
Abstract
The C-terminal region of cardiac troponin I (cTnI) is known to be important in cardiac function, as removal of the last 17 C-terminal residues of human cTnI has been associated with myocardial stunning. To investigate the C-terminal region of cTnI, three C-terminal deletion mutations in human cTnI were generated: Δ1 (deletion of residue 210), Δ3 (deletion of residues 208-210), and Δ5 (deletion of residues 206-210). Mammalian two-hybrid studies showed that the interactions between cTnI mutants and cardiac troponin C (cTnC) or cardiac troponin T (cTnT) were impaired in Δ3 and Δ5 mutants when compared to wild-type cTnI. Troponin complexes containing 2-[4'-(iodoacetamido) anilino] naphthalene-6-sulfonic acid (IAANS) labeled cTnC showed that the troponin complex containing cTnI Δ5 had a small increase in Ca(2+) affinity (P < 0.05); while the cTnI Δ1- and Δ3 troponin complexes showed no difference in Ca(2+) affinity when compared to wild-type troponin. In vitro motility assays showed that all truncation mutants had increased Ca(2+) dependent motility relative to wild-type cTnI. These results suggest that the last 5 C-terminal residues of cTnI influence the binding of cTnI with cTnC and cTnT and affect the Ca(2+) dependence of filament sliding, and demonstrate the importance of this region of cTnI.
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Affiliation(s)
- Jennifer E Gilda
- Department of Neurobiology, Physiology, and Behavior, University of California, Davis, 95616, USA
| | - Qian Xu
- Department of Neurobiology, Physiology, and Behavior, University of California, Davis, 95616, USA
| | - Margaret E Martinez
- Department of Biological Science, Florida State University, Tallahassee, FL, 32306, USA
| | - Susan T Nguyen
- Department of Neurobiology, Physiology, and Behavior, University of California, Davis, 95616, USA
| | - P Bryant Chase
- Department of Biological Science, Florida State University, Tallahassee, FL, 32306, USA
| | - Aldrin V Gomes
- Department of Neurobiology, Physiology, and Behavior, University of California, Davis, 95616, USA.
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Abstract
As a greater proportion of patients survive their initial cardiac insult, medical systems worldwide are being faced with an ever-growing need to understand the mechanisms behind the pathogenesis of chronic heart failure (HF). There is a wealth of information about the role of inflammatory cells and pathways during acute injury and the reparative processes that are subsequently activated. We discuss the different causes that lead to chronic HF development and how the sum of initial inflammatory and reparative responses only sets the trajectory for disease progression. Unfortunately, comparatively little is known about the contribution of the immune system once the trajectory has been set, and chronic HF has been established—which clinically represents the majority of patients. It is known that chronic HF is associated with circulating inflammatory cytokines that can predict clinical outcomes, yet the causative role inflammation plays in disease progression is not well defined, and the majority of clinical trials that target aspects of inflammation in patients with chronic HF have largely been negative. This review will present what is currently known about inflammation in chronic HF in both humans and animal models as a means to highlight the gap in our knowledge base that requires further examination.
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Affiliation(s)
- Sarah A. Dick
- From the Division of Cardiology, Department of Medicine, University Health Network, Toronto, Ontario, Canada (S.A.D, S.E.); University of Toronto, Toronto, Ontario, Canada (S.E); Peter Munk Cardiac Centre, Toronto, Ontario, Canada (S.A.D, S.E.); and Toronto General Hospital Research Institute, Toronto, Ontario, Canada (S.A.D, S.E.)
| | - Slava Epelman
- From the Division of Cardiology, Department of Medicine, University Health Network, Toronto, Ontario, Canada (S.A.D, S.E.); University of Toronto, Toronto, Ontario, Canada (S.E); Peter Munk Cardiac Centre, Toronto, Ontario, Canada (S.A.D, S.E.); and Toronto General Hospital Research Institute, Toronto, Ontario, Canada (S.A.D, S.E.)
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24
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Gilda JE, Lai X, Witzmann FA, Gomes AV. Delineation of Molecular Pathways Involved in Cardiomyopathies Caused by Troponin T Mutations. Mol Cell Proteomics 2016; 15:1962-81. [PMID: 27022107 DOI: 10.1074/mcp.m115.057380] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Indexed: 11/06/2022] Open
Abstract
Familial hypertrophic cardiomyopathy (FHC) is associated with mild to severe cardiac problems and is the leading cause of sudden death in young people and athletes. Although the genetic basis for FHC is well-established, the molecular mechanisms that ultimately lead to cardiac dysfunction are not well understood. To obtain important insights into the molecular mechanism(s) involved in FHC, hearts from two FHC troponin T models (Ile79Asn [I79N] and Arg278Cys [R278C]) were investigated using label-free proteomics and metabolomics. Mutations in troponin T are the third most common cause of FHC, and the I79N mutation is associated with a high risk of sudden cardiac death. Most FHC-causing mutations, including I79N, increase the Ca(2+) sensitivity of the myofilament; however, the R278C mutation does not alter Ca(2+) sensitivity and is associated with a better prognosis than most FHC mutations. Out of more than 1200 identified proteins, 53 and 76 proteins were differentially expressed in I79N and R278C hearts, respectively, when compared with wild-type hearts. Interestingly, more than 400 proteins were differentially expressed when the I79N and R278C hearts were directly compared. The three major pathways affected in I79N hearts relative to R278C and wild-type hearts were the ubiquitin-proteasome system, antioxidant systems, and energy production pathways. Further investigation of the proteasome system using Western blotting and activity assays showed that proteasome dysfunction occurs in I79N hearts. Metabolomic results corroborate the proteomic data and suggest the glycolytic, citric acid, and electron transport chain pathways are important pathways that are altered in I79N hearts relative to R278C or wild-type hearts. Our findings suggest that impaired energy production and protein degradation dysfunction are important mechanisms in FHCs associated with poor prognosis and that cardiac hypertrophy is not likely needed for a switch from fatty acid to glucose metabolism.
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Affiliation(s)
| | - Xianyin Lai
- ¶Department of Cellular and Integrative Physiology, Indiana University School of Medicine, Indianapolis, Indiana 46202
| | - Frank A Witzmann
- ¶Department of Cellular and Integrative Physiology, Indiana University School of Medicine, Indianapolis, Indiana 46202
| | - Aldrin V Gomes
- From the ‡Department of Neurobiology, Physiology, and Behavior, §Department of Physiology and Membrane Biology, University of California, Davis, California 95616;
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25
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Gollapudi SK, Chandra M. The effect of cardiomyopathy mutation (R97L) in mouse cardiac troponin T on the muscle length-mediated recruitment of crossbridges is modified divergently by α- and β-myosin heavy chain. Arch Biochem Biophys 2016; 601:105-12. [PMID: 26792537 DOI: 10.1016/j.abb.2016.01.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2015] [Revised: 12/28/2015] [Accepted: 01/08/2016] [Indexed: 01/19/2023]
Abstract
Hypertrophic cardiomyopathy mutations in cardiac troponin T (TnT) lead to sudden cardiac death. Augmented myofilament Ca(2+) sensitivity is a common feature in TnT mutants, but such observations fail to provide a rational explanation for severe cardiac phenotypes. To better understand the mutation-induced effect on the cardiac phenotype, it is imperative to determine the effects on dynamic contractile features such as the muscle length (ML)-mediated activation against α- and β-myosin heavy chain (MHC) isoforms. α- and β-MHC are not only differentially expressed in rodent and human hearts, but they also modify ML-mediated activation differently. Mouse analog of human TnTR94L (TnTR97L) or wild-type TnT was reconstituted into de-membranated muscle fibers from normal (α-MHC) and transgenic (β-MHC) mouse hearts. TnTR97L augmented myofilament Ca(2+) sensitivity by a similar amount in α- and β-MHC fibers. However, TnTR97L augmented the negative impact of strained crossbridges on other crossbridges (γ) by 22% in α-MHC fibers, but attenuated γ by 21% in β-MHC fibers. TnTR97L decreased the magnitude of ML-mediated recruitment of crossbridges (ER) by 37% in α-MHC fibers, but increased ER by 35% in β-MHC fibers. We provide a mechanistic basis for the TnTR97L-induced effects in α- and β-MHC fibers and discuss the relevance to human hearts.
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Affiliation(s)
- Sampath K Gollapudi
- Department of Integrative Physiology and Neuroscience (IPN), Washington State University, Pullman, WA, USA
| | - Murali Chandra
- Department of Integrative Physiology and Neuroscience (IPN), Washington State University, Pullman, WA, USA.
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26
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James J, Robbins J. Bringing It All Together: Bedside to Bench and Back Again. Circ Res 2015; 117:987-9. [PMID: 26635381 DOI: 10.1161/circresaha.115.307874] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Jeanne James
- From the Department of Pediatrics, The Heart Institute, Cincinnati Children's Hospital Medical Center, OH
| | - Jeffrey Robbins
- From the Department of Pediatrics, The Heart Institute, Cincinnati Children's Hospital Medical Center, OH.
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27
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Huang W, Szczesna-Cordary D. Molecular mechanisms of cardiomyopathy phenotypes associated with myosin light chain mutations. J Muscle Res Cell Motil 2015; 36:433-45. [PMID: 26385864 DOI: 10.1007/s10974-015-9423-3] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Accepted: 09/10/2015] [Indexed: 12/14/2022]
Abstract
We discuss here the potential mechanisms of action associated with hypertrophic (HCM) or dilated (DCM) cardiomyopathy causing mutations in the myosin regulatory (RLC) and essential (ELC) light chains. Specifically, we focus on four HCM mutations: RLC-A13T, RLC-K104E, ELC-A57G and ELC-M173V, and one DCM RLC-D94A mutation shown by population studies to cause different cardiomyopathy phenotypes in humans. Our studies indicate that RLC and ELC mutations lead to heart disease through different mechanisms with RLC mutations triggering alterations of the secondary structure of the RLC which further affect the structure and function of the lever arm domain and impose changes in the cross bridge cycling rates and myosin force generation ability. The ELC mutations exert their detrimental effects through changes in the interaction of the N-terminus of ELC with actin altering the cross talk between the thick and thin filaments and ultimately resulting in an altered force-pCa relationship. We also discuss the effect of mutations on myosin light chain phosphorylation. Exogenous myosin light chain phosphorylation and/or pseudo-phosphorylation were explored as potential rescue tools to treat hypertrophy-related cardiac phenotypes.
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Affiliation(s)
- Wenrui Huang
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL, 33136, USA
| | - Danuta Szczesna-Cordary
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL, 33136, USA.
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28
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Effects of cardiac Myosin binding protein-C on actin motility are explained with a drag-activation-competition model. Biophys J 2015; 108:10-3. [PMID: 25564844 DOI: 10.1016/j.bpj.2014.11.1852] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2014] [Revised: 10/31/2014] [Accepted: 11/11/2014] [Indexed: 01/26/2023] Open
Abstract
Although mutations in cardiac myosin binding protein-C (cMyBP-C) cause heart disease, its role in muscle contraction is not well understood. A mechanism remains elusive partly because the protein can have multiple effects, such as dual biphasic activation and inhibition observed in actin motility assays. Here we develop a mathematical model for the interaction of cMyBP-C with the contractile proteins actin and myosin and the regulatory protein tropomyosin. We use this model to show that a drag-activation-competition mechanism accurately describes actin motility measurements, while models lacking either drag or competition do not. These results suggest that complex effects can arise simply from cMyBP-C binding to actin.
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29
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Chandra V, Gollapudi SK, Chandra M. Rat cardiac troponin T mutation (F72L)-mediated impact on thin filament cooperativity is divergently modulated by α- and β-myosin heavy chain isoforms. Am J Physiol Heart Circ Physiol 2015; 309:H1260-70. [PMID: 26342069 DOI: 10.1152/ajpheart.00519.2015] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Accepted: 08/31/2015] [Indexed: 11/22/2022]
Abstract
The primary causal link between disparate effects of human hypertrophic cardiomyopathy (HCM)-related mutations in troponin T (TnT) and α- and β-myosin heavy chain (MHC) isoforms on cardiac contractile phenotype remains poorly understood. Given the divergent impact of α- and β-MHC on the NH2-terminal extension (44-73 residues) of TnT, we tested if the effects of the HCM-linked mutation (TnTF70L) were differentially altered by α- and β-MHC. We hypothesized that the emergence of divergent thin filament cooperativity would lead to contrasting effects of TnTF70L on contractile function in the presence of α- and β-MHC. The rat TnT analog of the human F70L mutation (TnTF72L) or the wild-type rat TnT (TnTWT) was reconstituted into demembranated muscle fibers from normal (α-MHC) and propylthiouracil-treated (β-MHC) rat hearts to measure steady-state and dynamic contractile function. TnTF72L-mediated effects on tension, myofilament Ca(2+) sensitivity, myofilament cooperativity, rate constants of cross-bridge (XB) recruitment dynamics, and force redevelopment were divergently modulated by α- and β-MHC. TnTF72L increased the rate of XB distortion dynamics by 49% in α-MHC fibers but had no effect in β-MHC fibers; these observations suggest that TnTF72L augmented XB detachment kinetics in α-MHC, but not β-MHC, fibers. TnTF72L increased the negative impact of strained XBs on the force-bearing XBs by 39% in α-MHC fibers but had no effect in β-MHC fibers. Therefore, TnTF72L leads to contractile changes that are linked to dilated cardiomyopathy in the presence of α-MHC. On the other hand, TnTF72L leads to contractile changes that are linked to HCM in the presence of β-MHC.
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Affiliation(s)
- Vikram Chandra
- Department of Integrative Physiology and Neuroscience, Washington State University, Pullman, Washington
| | - Sampath K Gollapudi
- Department of Integrative Physiology and Neuroscience, Washington State University, Pullman, Washington
| | - Murali Chandra
- Department of Integrative Physiology and Neuroscience, Washington State University, Pullman, Washington
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30
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Hussein A, Karimianpour A, Collier P, Krasuski RA. Isolated Noncompaction of the Left Ventricle in Adults. J Am Coll Cardiol 2015; 66:578-85. [DOI: 10.1016/j.jacc.2015.06.017] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/12/2015] [Revised: 06/09/2015] [Accepted: 06/10/2015] [Indexed: 10/23/2022]
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31
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Pu T, Guo Q, Cao R, Xu R, Sun K, Chen S. Using exome sequencing to identify the cause of myocardial hypertrophy in a Chinese family. Mol Med Rep 2015; 12:3662-3666. [PMID: 25997934 DOI: 10.3892/mmr.2015.3818] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2014] [Accepted: 04/15/2015] [Indexed: 11/05/2022] Open
Abstract
Myocardial hypertrophy is a common feature of numerous diseases. It is important to distinguish between these diseases in order to enable accurate diagnosis and the administration of appropriate therapy. Using whole‑exome sequencing, the present study aimed to identify a pathogenic mutation in a Chinese family, which may lead to cardiac hypertrophy and Wolff‑Parkinson‑White syndrome. The proband from the Chinese family exhibited left ventricular hypertrophy and pre-excitation with a short PR interval. DNA was extracted from peripheral blood obtained from the subject family, and exome sequencing was performed in the proband. Polymerase chain reaction and direct sequencing were used to confirm the presence of a mutation, and confirmed that the pathogenic mutation was 5'-AMP‑activated protein kinase subunit γ2 (PRKAG2) (p.R302Q), which has been previously reported in a family with an inherited from of WPW. A stop‑gain mutation in urotensin II receptor (UTS2R) (p.S241X), which is associated with congestive heart failure, was identified in the proband and in one other affected family member. It is important to identify the causes of myocardial hypertrophy, in order to provide a theoretical basis with which to improve clinical diagnosis and the assessment of prognosis. The results of the present study suggest that if a patient has myocardial hypertrophy with a short PR interval on electrocardiogram, a mutation in the PRKAG2 gene should be considered. In conclusion, exome sequencing methods may assist with the identification of causative genes in myocardial hypertrophy, as well as genes that are associated with an increased risk of sudden cardiac death.
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Affiliation(s)
- Tian Pu
- Department of Pediatric Cardiology, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200092, P.R. China
| | - Qianqian Guo
- Department of Pediatric Cardiology, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200092, P.R. China
| | - Ruixue Cao
- Department of Pediatric Cardiology, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200092, P.R. China
| | - Rang Xu
- Scientific Research Center, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200092, P.R. China
| | - Kun Sun
- Department of Pediatric Cardiology, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200092, P.R. China
| | - Sun Chen
- Department of Pediatric Cardiology, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200092, P.R. China
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32
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Spudich JA. Hypertrophic and dilated cardiomyopathy: four decades of basic research on muscle lead to potential therapeutic approaches to these devastating genetic diseases. Biophys J 2014; 106:1236-49. [PMID: 24655499 PMCID: PMC3985504 DOI: 10.1016/j.bpj.2014.02.011] [Citation(s) in RCA: 198] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2013] [Revised: 01/30/2014] [Accepted: 02/04/2014] [Indexed: 01/10/2023] Open
Abstract
With the advent of technologies to obtain the complete sequence of the human genome in a cost-effective manner, this decade and those to come will see an exponential increase in our understanding of the underlying genetics that lead to human disease. And where we have a deep understanding of the biochemical and biophysical basis of the machineries and pathways involved in those genetic changes, there are great hopes for the development of modern therapeutics that specifically target the actual machinery and pathways altered by individual mutations. Prime examples of such a genetic disease are those classes of hypertrophic and dilated cardiomyopathy that result from single amino-acid substitutions in one of several of the proteins that make up the cardiac sarcomere or from the truncation of myosin binding protein C. Hypertrophic cardiomyopathy alone affects ∼1 in 500 individuals, and it is the leading cause of sudden cardiac death in young adults. Here I describe approaches to understand the molecular basis of the alterations in power output that result from these mutations. Small molecules binding to the mutant sarcomeric protein complex should be able to mitigate the effects of hypertrophic and dilated cardiomyopathy mutations at their sources, leading to possible new therapeutic approaches for these genetic diseases.
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Affiliation(s)
- James A Spudich
- Department of Biochemistry, Stanford University School of Medicine, Stanford, California.
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33
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Belknap B, Harris SP, White HD. Modulation of thin filament activation of myosin ATP hydrolysis by N-terminal domains of cardiac myosin binding protein-C. Biochemistry 2014; 53:6717-24. [PMID: 25265574 PMCID: PMC4211651 DOI: 10.1021/bi500787f] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
![]()
We
have used enzyme kinetics to investigate the molecular mechanism
by which the N-terminal domains of human and mouse cardiac MyBP-C
(C0C1, C1C2, and C0C2) affect the activation of myosin ATP hydrolysis
by F-actin and by native porcine thin filaments. N-Terminal domains
of cMyBP-C inhibit the activation of myosin-S1 ATPase by F-actin.
However, mouse and human C1C2 and C0C2 produce biphasic activating
and inhibitory effects on the activation of myosin ATP hydrolysis
by native cardiac thin filaments. Low ratios of MyBP-C N-terminal
domains to thin filaments activate myosin-S1 ATP hydrolysis, but higher
ratios inhibit ATP hydrolysis, as is observed with F-actin alone.
These data suggest that low concentrations of C1C2 and C0C2 activate
thin filaments by a mechanism similar to that of rigor myosin-S1,
whereas higher concentrations inhibit the ATPase rate by competing
with myosin-S1-ADP-Pi for binding to actin and thin filaments.
In contrast to C0C2 and C1C2, the activating effects of the C0C1 domain
are species-dependent: human C0C1 activates actomyosin-S1 ATPase rates,
but mouse C0C1 does not produce significant activation or inhibition.
Phosphorylation of serine residues in the m-linker between the C1
and C2 domains by protein kinase-A decreases the activation of thin
filaments by huC0C2 at pCa > 8 but
has
little effect on the activation mechanism at pCa = 4. In sarcomeres, the low ratio of cMyBP-C to actin is
expected to favor the activating effects of cMyBP-C while minimizing
inhibition produced by competition with myosin heads.
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Affiliation(s)
- Betty Belknap
- Department of Physiological Sciences, Eastern Virginia Medical School , Norfolk, Virginia 23507, United States
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34
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Haberer K, Buffo-Sequeira I, Chudley AE, Spriggs E, Sergi C. A Case of an Infant With Compound Heterozygous Mutations for Hypertrophic Cardiomyopathy Producing a Phenotype of Left Ventricular Noncompaction. Can J Cardiol 2014; 30:1249.e1-3. [DOI: 10.1016/j.cjca.2014.05.021] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2013] [Revised: 05/08/2014] [Accepted: 05/28/2014] [Indexed: 11/26/2022] Open
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35
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Månsson A. Hypothesis and theory: mechanical instabilities and non-uniformities in hereditary sarcomere myopathies. Front Physiol 2014; 5:350. [PMID: 25309450 PMCID: PMC4163974 DOI: 10.3389/fphys.2014.00350] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2014] [Accepted: 08/26/2014] [Indexed: 12/23/2022] Open
Abstract
Familial hypertrophic cardiomyopathy (HCM), due to point mutations in genes for sarcomere proteins such as myosin, occurs in 1/500 people and is the most common cause of sudden death in young individuals. Similar mutations in skeletal muscle, e.g., in the MYH7 gene for slow myosin found in both the cardiac ventricle and slow skeletal muscle, may also cause severe disease but the severity and the morphological changes are often different. In HCM, the modified protein function leads, over years to decades, to secondary remodeling with substantial morphological changes, such as hypertrophy, myofibrillar disarray, and extensive fibrosis associated with severe functional deterioration. Despite intense studies, it is unclear how the moderate mutation-induced changes in protein function cause the long-term effects. In hypertrophy of the heart due to pressure overload (e.g., hypertension), mechanical stress in the myocyte is believed to be major initiating stimulus for activation of relevant cell signaling cascades. Here it is considered how expression of mutated proteins, such as myosin or regulatory proteins, could have similar consequences through one or both of the following mechanisms: (1) contractile instabilities within each sarcomere (with more than one stable velocity for a given load), (2) different tension generating capacities of cells in series. These mechanisms would have the potential to cause increased tension and/or stretch of certain cells during parts of the cardiac cycle. Modeling studies are used to illustrate these ideas and experimental tests are proposed. The applicability of similar ideas to skeletal muscle is also postulated, and differences between heart and skeletal muscle are discussed.
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Affiliation(s)
- Alf Månsson
- Department of Chemistry and Biomedical Sciences, Linnaeus University Kalmar, Sweden
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36
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Kanthaswamy S, Reader R, Tarara R, Oslund K, Allen M, Ng J, Grinberg C, Hyde D, Glenn DG, Lerche N. Large scale pedigree analysis leads to evidence for founder effects of Hypertrophic Cardiomyopathy in Rhesus Macaques ( Macaca mulatta). J Med Primatol 2014; 43:288-291. [PMID: 25422529 PMCID: PMC4240635 DOI: 10.1111/jmp.12127] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Hypertrophic Cardiomyopathy (HCM) is the abnormal thickening of the ventricles and an increase in cardiac mass. Analyses of 108 rhesus macaque probands with pronounced HCM revealed a strong genetic predisposition to this disease. Macaques are ideal for investigating HCM because of their marked similarity to humans genetically, physiologically and anatomically.
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Affiliation(s)
- Sree Kanthaswamy
- Department of Anthropology, University of California, Davis, CA 95616
- California National Primate Research Center, University of California, Davis, CA 95616
- Department of Environmental Toxicology, University of California, Davis, CA 95616
| | - Rachel Reader
- California National Primate Research Center, University of California, Davis, CA 95616
| | - Ross Tarara
- California National Primate Research Center, University of California, Davis, CA 95616
| | - Karen Oslund
- California National Primate Research Center, University of California, Davis, CA 95616
| | - Mark Allen
- California National Primate Research Center, University of California, Davis, CA 95616
| | - Jillian Ng
- California National Primate Research Center, University of California, Davis, CA 95616
| | - Chloe Grinberg
- California National Primate Research Center, University of California, Davis, CA 95616
| | - Dallas Hyde
- California National Primate Research Center, University of California, Davis, CA 95616
- School of Veterinary Medicine, University of California, Davis, CA 95616
| | - David Glenn Glenn
- Department of Anthropology, University of California, Davis, CA 95616
- California National Primate Research Center, University of California, Davis, CA 95616
| | - Nicholas Lerche
- California National Primate Research Center, University of California, Davis, CA 95616
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37
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Guo Q, Xu Y, Wang X, Guo Y, Xu R, Sun K, Chen S. Exome sequencing identifies a novel MYH7 p.G407C mutation responsible for familial hypertrophic cardiomyopathy. DNA Cell Biol 2014; 33:699-704. [PMID: 24963656 DOI: 10.1089/dna.2014.2483] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Hypertrophic cardiomyopathy (HCM), characterized by myocardial hypertrophy, is the most common cause of sudden cardiac arrest in young individuals. More than 270 mutations have been found to be responsible for familial HCM to date; mutations in MYH7, which encodes the β-myosin heavy chain (β-MHC) and MYBPC3, which encodes the myosin binding protein C, are seen most often. This study aimed to screen a pathogenic mutation causing HCM in a large family and assess its possible impact on the function of the specific protein. Exome sequencing was applied in the proband for searching a novel mutation; segments bearing the specific mutation were analyzed by polymerase chain reaction and direct sequencing. A novel p.G407C mutation in the β-MHC gene (MYH7) was identified to be responsible for familial HCM in this family. The mutation may cause damage to the second structure of the protein despite the fact that patients bearing the mutation may have a relatively benign prognosis in this family. The clinical details of the p.G407C mutation are described for the first time in this study. Our report shows a good genotype-phenotype consistency and makes it possible for genetic counseling in this family.
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Affiliation(s)
- Qianqian Guo
- 1 Department of Pediatric Cardiovascular, Xinhua Hospital Affiliated to Medical School of Shanghai Jiaotong University , Shanghai, People's Republic of China
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38
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Kuster DWD, Sadayappan S. MYBPC3's alternate ending: consequences and therapeutic implications of a highly prevalent 25 bp deletion mutation. Pflugers Arch 2014; 466:207-13. [PMID: 24327208 PMCID: PMC3946836 DOI: 10.1007/s00424-013-1417-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2013] [Revised: 11/27/2013] [Accepted: 12/02/2013] [Indexed: 11/25/2022]
Abstract
Hypertrophic cardiomyopathy (HCM) is the most common form of inherited cardiac disease and the leading cause of sudden cardiac death in young people. HCM is caused by mutations in genes encoding contractile proteins. Cardiac myosin binding protein-C (cMyBP-C) is a thick filament contractile protein that regulates sarcomere organization and cardiac contractility. About 200 different mutations in the cMyBP-C gene (MYBPC3) have thus far been reported as causing HCM. Among them, a 25 base pair deletion in the branch point of intron 32 of MYBPC3 is widespread, particularly affecting people of South Asian descent, with 4% of this population carrying the mutation. This polymorphic mutation results in skipping of exon 33 and a reading frame shift, which, in turn, replaces the last 65 amino acids of the C-terminal C10 domain of cMyBP-C with a novel sequence of 58 residues (cMyBP-C(C10mut)). Carriers of the 25 base pair deletion mutation are at increased risk of developing cardiomyopathy and heart failure. Because of the high prevalence of this mutation in certain populations, genetic screening of at-risk groups might be beneficial. Scientifically, the functional consequences of C-terminal mutations and the precise mechanisms leading to HCM should be defined using induced pluripotent stem cells and engineered heart tissue in vitro or mouse models in vivo. Most importantly, therapeutic strategies that include pharmacology, gene repair, and gene therapy should be developed to prevent the adverse clinical effects of cMyBP-C(C10mut). This review article aims to examine the effects of cMyBP-C(C10mut) on cardiac function, emphasizing the need for the development of genetic testing and expanded therapeutic strategies.
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Affiliation(s)
- Diederik W. D. Kuster
- Department of Cell and Molecular Physiology, Health Sciences Division, Loyola University Chicago, Maywood, IL 60153-5500, USA,
| | - Sakthivel Sadayappan
- Department of Cell and Molecular Physiology, Health Sciences Division, Loyola University Chicago, Maywood, IL 60153-5500, USA, Phone: 708-216-7994, Fax: 708-216-6308,
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39
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Karsai Á, Kellermayer MSZ, Harris SP. Cross-species mechanical fingerprinting of cardiac myosin binding protein-C. Biophys J 2014; 104:2465-75. [PMID: 23746519 DOI: 10.1016/j.bpj.2013.04.027] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Revised: 01/19/2013] [Accepted: 04/08/2013] [Indexed: 01/22/2023] Open
Abstract
Cardiac myosin binding protein-C (cMyBP-C) is a member of the immunoglobulin (Ig) superfamily of proteins and consists of 8 Ig- and 3 fibronectin III (FNIII)-like domains along with a unique regulatory sequence referred to as the MyBP-C motif or M-domain. We previously used atomic force microscopy to investigate the mechanical properties of murine cMyBP-C expressed using a baculovirus/insect cell expression system. Here, we investigate whether the mechanical properties of cMyBP-C are conserved across species by using atomic force microscopy to manipulate recombinant human cMyBP-C and native cMyBP-C purified from bovine heart. Force versus extension data obtained in velocity-clamp experiments showed that the mechanical response of the human recombinant protein was remarkably similar to that of the bovine native cMyBP-C. Ig/Fn-like domain unfolding events occurred in a hierarchical fashion across a threefold range of forces starting at relatively low forces of ~50 pN and ending with the unfolding of the highest stability domains at ~180 pN. Force-extension traces were also frequently marked by the appearance of anomalous force drops suggestive of additional mechanical complexity such as structural coupling among domains. Both recombinant and native cMyBP-C exhibited a prominent segment ~100 nm-long that could be stretched by forces <50 pN before the unfolding of Ig- and FN-like domains. Combined with our previous observations of mouse cMyBP-C, these results establish that although the response of cMyBP-C to mechanical load displays a complex pattern, it is highly conserved across species.
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Affiliation(s)
- Árpád Karsai
- University of California - Davis, Davis, CA, USA
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40
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Sequeira V, Witjas-Paalberends ER, Kuster DWD, van der Velden J. Cardiac myosin-binding protein C: hypertrophic cardiomyopathy mutations and structure-function relationships. Pflugers Arch 2013; 466:201-6. [PMID: 24240729 DOI: 10.1007/s00424-013-1400-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2013] [Revised: 10/30/2013] [Accepted: 10/31/2013] [Indexed: 01/05/2023]
Abstract
Cardiac myosin-binding protein C (cMyBP-C) research has been characterized by two waves. Initial interest was piqued by its discovery in 1973 as a contaminant of myosin preparations from skeletal muscle. The second wave started in 1995 by the discovery that mutations in the gene encoding cMyBP-C cause hypertrophic cardiomyopathy (HCM). In this review, we will address what is known of cMyBP-C's role as a regulator of contraction as well as its role in HCM.
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Affiliation(s)
- Vasco Sequeira
- Department of Physiology, Institute for Cardiovascular Research (ICaR-VU), VU University Medical Center, van der Boechorststraat 7, 1081, BT, Amsterdam, The Netherlands
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41
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Ryan TD, Gupta A, Gupta D, Goldenberg P, Taylor MD, Lorts A, Jefferies JL. Dilated cardiomyopathy in a 32-year-old woman with Russell-Silver syndrome. Cardiovasc Pathol 2013; 23:21-7. [PMID: 24075556 DOI: 10.1016/j.carpath.2013.08.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2013] [Revised: 08/08/2013] [Accepted: 08/14/2013] [Indexed: 10/26/2022] Open
Abstract
INTRODUCTION Russell-Silver Syndrome (RSS) is a genetically determined condition characterized by severe intrauterine and postnatal growth retardation; relative macrocephaly; a small, triangular face; and fifth-finger clinodactyly. The etiology of RSS involves epigenetic regulation through either uniparental disomy or genomic imprinting via DNA methylation. There has been no documented association between RSS and cardiomyopathy. METHODS We present an original case of a 32-year-old woman with RSS with dilated a cardiomyopathy who on cardiac biopsy showed occasional hypertrophic and atrophic myocytes with no evidence of inflammation, abnormal sarcomeres and disintegration of the Z bands on ultrastructural analysis, abnormal desmin, and normal C9 immunoreactivity. CONCLUSION This case represents the first reported association between RSS and cardiomyopathy. Given the complex mechanisms of disease etiology in RSS, this novel case provides insights into the mechanism of progressive dilated cardiomyopathy in an older individual with RSS.
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Affiliation(s)
- Thomas D Ryan
- The Heart Institute, Cincinnati Children's Hospital, Cincinnati, OH 45229, USA
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Wolny M, Colegrave M, Colman L, White E, Knight PJ, Peckham M. Cardiomyopathy mutations in the tail of β-cardiac myosin modify the coiled-coil structure and affect integration into thick filaments in muscle sarcomeres in adult cardiomyocytes. J Biol Chem 2013; 288:31952-62. [PMID: 24047955 DOI: 10.1074/jbc.m113.513291] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
It is unclear why mutations in the filament-forming tail of myosin heavy chain (MHC) cause hypertrophic or dilated cardiomyopathy as these mutations should not directly affect contraction. To investigate this, we first investigated the impact of five hypertrophic cardiomyopathy-causing (N1327K, E1356K, R1382W, E1555K, and R1768K) and one dilated cardiomyopathy-causing (R1500W) tail mutations on their ability to incorporate into muscle sarcomeres in vivo. We used adenoviral delivery to express full-length wild type or mutant enhanced GFP-MHC in isolated adult cardiomyocytes. Three mutations (N1327K, E1356K, and E1555K) reduced enhanced GFP-MHC incorporation into muscle sarcomeres, whereas the remainder had no effect. No mutations significantly affected contraction. Fluorescence recovery after photobleaching showed that fluorescence recovery for the mutation that incorporated least well (N1327K) was significantly faster than that of WT with half-times of 25.1 ± 1.8 and 32.2 ± 2.5 min (mean ± S.E.), respectively. Next, we determined the effects of each mutation on the helical properties of wild type and seven mutant peptides (7, 11, or 15 heptads long) from the myosin tail by circular dichroism. R1382W and E1768K slightly increased the α-helical nature of peptides. The remaining mutations reduced α-helical content, with N1327K showing the greatest reduction. Only peptides containing residues 1301-1329 were highly α-helical suggesting that this region helps in initiation of coiled coil. These results suggest that small effects of mutations on helicity translate into a reduced ability to incorporate into sarcomeres, which may elicit compensatory hypertrophy.
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Affiliation(s)
- Marcin Wolny
- From the School of Molecular and Cellular Biology and
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Hagen CM, Aidt FH, Hedley PL, Jensen MK, Havndrup O, Kanters JK, Moolman-Smook JC, Larsen SO, Bundgaard H, Christiansen M. Mitochondrial haplogroups modify the risk of developing hypertrophic cardiomyopathy in a Danish population. PLoS One 2013; 8:e71904. [PMID: 23940792 PMCID: PMC3734310 DOI: 10.1371/journal.pone.0071904] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2013] [Accepted: 07/08/2013] [Indexed: 12/11/2022] Open
Abstract
Hypertrophic cardiomyopathy (HCM) is a genetic disorder caused by mutations in genes coding for proteins involved in sarcomere function. The disease is associated with mitochondrial dysfunction. Evolutionarily developed variation in mitochondrial DNA (mtDNA), defining mtDNA haplogroups and haplogroup clusters, is associated with functional differences in mitochondrial function and susceptibility to various diseases, including ischemic cardiomyopathy. We hypothesized that mtDNA haplogroups, in particular H, J and K, might modify disease susceptibility to HCM. Mitochondrial DNA, isolated from blood, was sequenced and haplogroups identified in 91 probands with HCM. The association with HCM was ascertained using two Danish control populations. Haplogroup H was more prevalent in HCM patients, 60% versus 46% (p = 0.006) and 41% (p = 0.003), in the two control populations. Haplogroup J was less prevalent, 3% vs. 12.4% (p = 0.017) and 9.1%, (p = 0.06). Likewise, the UK haplogroup cluster was less prevalent in HCM, 11% vs. 22.1% (p = 0.02) and 22.8% (p = 0.04). These results indicate that haplogroup H constitutes a susceptibility factor and that haplogroup J and haplogroup cluster UK are protective factors in the development of HCM. Thus, constitutive differences in mitochondrial function may influence the occurrence and clinical presentation of HCM. This could explain some of the phenotypic variability in HCM. The fact that haplogroup H and J are also modifying factors in ischemic cardiomyopathy suggests that mtDNA haplotypes may be of significance in determining whether a physiological hypertrophy develops into myopathy. mtDNA haplotypes may have the potential of becoming significant biomarkers in cardiomyopathy.
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Affiliation(s)
- Christian M. Hagen
- Department of Clinical Biochemistry and Immunology, Statens Serum Institut, Copenhagen, Denmark
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Frederik H. Aidt
- Department of Clinical Biochemistry and Immunology, Statens Serum Institut, Copenhagen, Denmark
| | - Paula L. Hedley
- Department of Clinical Biochemistry and Immunology, Statens Serum Institut, Copenhagen, Denmark
- Department of Biomedical Sciences, Stellenbosch University, Cape Town, South Africa
| | - Morten K. Jensen
- Department of Medicine B, Heart Center, Righospitalet, Copenhagen, Denmark
| | - Ole Havndrup
- Department of Cardiology, Roskilde Hospital, Roskilde, Denmark
| | - Jørgen K. Kanters
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
- Department of Cardiology, Gentofte University Hospital, Copenhagen, Denmark
| | | | - Severin O. Larsen
- Department of Clinical Biochemistry and Immunology, Statens Serum Institut, Copenhagen, Denmark
| | - Henning Bundgaard
- Department of Medicine B, Heart Center, Righospitalet, Copenhagen, Denmark
| | - Michael Christiansen
- Department of Clinical Biochemistry and Immunology, Statens Serum Institut, Copenhagen, Denmark
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Hagen CM, Aidt FH, Havndrup O, Hedley PL, Jespersgaard C, Jensen M, Kanters JK, Moolman-Smook JC, Møller DV, Bundgaard H, Christiansen M. MT-CYB mutations in hypertrophic cardiomyopathy. Mol Genet Genomic Med 2013; 1:54-65. [PMID: 24498601 PMCID: PMC3893158 DOI: 10.1002/mgg3.5] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2013] [Revised: 02/18/2013] [Accepted: 02/21/2013] [Indexed: 12/20/2022] Open
Abstract
Mitochondrial dysfunction is a characteristic of heart failure. Mutations in mitochondrial DNA, particularly in MT-CYB coding for cytochrome B in complex III (CIII), have been associated with isolated hypertrophic cardiomyopathy (HCM). We hypothesized that MT-CYB mutations might play an important causal or modifying role in HCM. The MT-CYB gene was sequenced from DNA isolated from blood from 91 Danish HCM probands. Nonsynonymous variants were analyzed by bioinformatics, molecular modeling and simulation. Two germline-inherited, putative disease-causing, nonsynonymous variants: m.15024G>A; p.C93Y and m.15482T>C; p.S246P were identified. Modeling showed that the p.C93Y mutation leads to disruption of the tertiary structure of Cytb by helix displacement, interfering with protein–heme interaction. The p.S246P mutation induces a diproline structure, which alters local secondary structure and induces a kink in the protein backbone, interfering with macromolecular interactions. These molecular effects are compatible with a leaky phenotype, that is, limited but progressive mitochondrial dysfunction. In conclusion, we find that rare, putative leaky mtDNA variants in MT-CYB can be identified in a cohort of HCM patients. We propose that further patients with HCM should be examined for mutations in MT-CYB in order to clarify the role of these variants.
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Affiliation(s)
- Christian M Hagen
- Department of Clinical Biochemistry, Immunology, and Genetics, Statens Serum Institut Copenhagen, Denmark ; Department of Biomedical Sciences, University of Copenhagen Copenhagen, Denmark
| | - Frederik H Aidt
- Department of Clinical Biochemistry, Immunology, and Genetics, Statens Serum Institut Copenhagen, Denmark ; Institute of Cellular and Molecular Medicine, Faculty of Health Sciences, University of Copenhagen Copenhagen, Denmark
| | - Ole Havndrup
- Department of Cardiology, Roskilde Sygehus Roskilde, Denmark
| | - Paula L Hedley
- Department of Clinical Biochemistry, Immunology, and Genetics, Statens Serum Institut Copenhagen, Denmark ; Department of Biomedical Sciences, Stellenbosch University Cape Town, South Africa
| | - Cathrine Jespersgaard
- Department of Clinical Biochemistry, Immunology, and Genetics, Statens Serum Institut Copenhagen, Denmark
| | - Morten Jensen
- Department of Medicine B, The Heart Center, Rigshospitalet Copenhagen, Denmark
| | - Jørgen K Kanters
- Department of Biomedical Sciences, University of Copenhagen Copenhagen, Denmark
| | | | - Daniel V Møller
- Department of Clinical Biochemistry, Immunology, and Genetics, Statens Serum Institut Copenhagen, Denmark
| | - Henning Bundgaard
- Department of Medicine B, The Heart Center, Rigshospitalet Copenhagen, Denmark
| | - Michael Christiansen
- Department of Clinical Biochemistry, Immunology, and Genetics, Statens Serum Institut Copenhagen, Denmark
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Fujita E, Nakanishi T, Nishizawa T, Hagiwara N, Matsuoka R. Mutations in the cardiac troponin T gene show various prognoses in Japanese patients with hypertrophic cardiomyopathy. Heart Vessels 2013; 28:785-94. [PMID: 23494605 PMCID: PMC3830204 DOI: 10.1007/s00380-013-0332-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/02/2012] [Accepted: 02/15/2013] [Indexed: 11/24/2022]
Abstract
Hypertrophic cardiomyopathy (HCM) is an autosomal dominant disorder resulting from mutations in genes for at least 15 various sarcomere-related proteins including cardiac β-myosin heavy chain, cardiac myosin-binding protein C, and cardiac troponin T. The troponin T gene (TNNT2) mutation has the third incidence of familial HCM, and the genotype–phenotype correlation of this gene still remains insufficient in Japanese familial HCM. Therefore, in the present study, we focused on screening the TNNT2 mutation in 173 unrelated Japanese patients with familial HCM, and found three reported mutations and a new mutation of TNNT2 in 11 individuals from four families. In these families, two individuals from one family had double mutations, Arg130Cys and Phe110Ile, six individuals from two other families had an Arg92Trp mutation, and one individual of another family had a new mutation, Ile79Thr, of TNNT2. The phenotype of each family was often different from reported cases, even if they had the same genetic mutation. In addition, families with the same genetic mutation showed a similar trend in the phenotype, but it was not exactly the same. However, sudden death in youth was observed in all of these families. Although the type of genetic mutation is not useful for predicting prognosis in HCM, the possibility of sudden cardiac death remains. Therefore, the prognosis of individuals bearing the TNNT2 mutation with familial HCM should be more carefully observed from birth.
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Affiliation(s)
- Etsuko Fujita
- Department of Cardiology, Tokyo Women's Medical University, Tokyo, Japan
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Longeri M, Ferrari P, Knafelz P, Mezzelani A, Marabotti A, Milanesi L, Pertica G, Polli M, Brambilla PG, Kittleson M, Lyons LA, Porciello F. Myosin-binding protein C DNA variants in domestic cats (A31P, A74T, R820W) and their association with hypertrophic cardiomyopathy. J Vet Intern Med 2013; 27:275-85. [PMID: 23323744 DOI: 10.1111/jvim.12031] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2012] [Revised: 09/09/2012] [Accepted: 11/06/2012] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND Two mutations in the MYBPC3 gene have been identified in Maine Coon (MCO) and Ragdoll (RD) cats with hypertrophic cardiomyopathy (HCM). OBJECTIVE This study examined the frequency of these mutations and of the A74T polymorphism to describe their worldwide distribution and correlation with echocardiography. ANIMALS 1855 cats representing 28 breeds and random-bred cats worldwide, of which 446 underwent echocardiographic examination. METHODS This is a prospective cross-sectional study. Polymorphisms were genotyped by Illumina VeraCode GoldenGate or by direct sequencing. The disease status was defined by echocardiography according to established guidelines. Odds ratios for the joint probability of having HCM and the alleles were calculated by meta-analysis. Functional analysis was simulated. RESULTS The MYBPC3 A31P and R820W were restricted to MCO and RD, respectively. Both purebred and random-bred cats had HCM and the incidence increased with age. The A74T polymorphism was not associated with any phenotype. HCM was most prevalent in MCO homozygote for the A31P mutation and the penetrance increased with age. The penetrance of the heterozygote genotype was lower (0.08) compared with the P/P genotype (0.58) in MCO. CONCLUSIONS AND CLINICAL IMPORTANCE A31P mutation occurs frequently in MCO cats. The high incidence of HCM in homozygotes for the mutation supports the causal nature of the A31P mutation. Penetrance is incomplete for heterozygotes at A31P locus, at least at a young age. The A74T variant does not appear to be correlated with HCM.
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Affiliation(s)
- M Longeri
- Dip. Scienze Veterinarie e Sanità Pubblica, University of Milan, Milan, Italy.
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Insights into restrictive cardiomyopathy from clinical and animal studies. J Geriatr Cardiol 2012; 8:168-83. [PMID: 22783303 PMCID: PMC3390071 DOI: 10.3724/sp.j.1263.2011.00168] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2011] [Revised: 08/24/2011] [Accepted: 08/31/2011] [Indexed: 01/13/2023] Open
Abstract
Cardiomyopathies are diseases that primarily affect the myocardium, leading to serious cardiac dysfunction and heart failure. Out of the three major categories of cardiomyopathies (hypertrophic, dilated and restrictive), restrictive cardiomyopathy (RCM) is less common and also the least studied. However, the prognosis for RCM is poor as some patients dying in their childhood. The molecular mechanisms behind the disease development and progression are not very clear and the treatment of RCM is very difficult and often ineffective. In this article, we reviewed the recent progress in RCM research from the clinical studies and the translational studies done on diseased transgenic animal models. This will help for a better understanding of the mechanisms underlying the etiology and development of RCM and for the design of better treatments for the disease.
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Cardiomyopathy classification: ongoing debate in the genomics era. Biochem Res Int 2012; 2012:796926. [PMID: 22924131 PMCID: PMC3423823 DOI: 10.1155/2012/796926] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2012] [Revised: 05/14/2012] [Accepted: 05/31/2012] [Indexed: 01/19/2023] Open
Abstract
Cardiomyopathies represent a group of diseases of the myocardium of the heart and include diseases both primarily of the cardiac muscle and systemic diseases leading to adverse effects on the heart muscle size, shape, and function. Traditionally cardiomyopathies were defined according to phenotypical appearance. Now, as our understanding of the pathophysiology of the different entities classified under each of the different phenotypes improves and our knowledge of the molecular and genetic basis for these entities progresses, the traditional classifications seem oversimplistic and do not reflect current understanding of this myriad of diseases and disease processes. Although our knowledge of the exact basis of many of the disease processes of cardiomyopathies is still in its infancy, it is important to have a classification system that has the ability to incorporate the coming tide of molecular and genetic information. This paper discusses how the traditional classification of cardiomyopathies based on morphology has evolved due to rapid advances in our understanding of the genetic and molecular basis for many of these clinical entities.
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Golbus JR, Puckelwartz MJ, Fahrenbach JP, Dellefave-Castillo LM, Wolfgeher D, McNally EM. Population-based variation in cardiomyopathy genes. ACTA ACUST UNITED AC 2012; 5:391-9. [PMID: 22763267 DOI: 10.1161/circgenetics.112.962928] [Citation(s) in RCA: 115] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
BACKGROUND Hypertrophic cardiomyopathy and dilated cardiomyopathy arise from mutations in genes encoding sarcomere proteins including MYH7, MYBPC3, and TTN. Genetic diagnosis of cardiomyopathy relies on complete sequencing of the gene coding regions, and most pathogenic variation is rare. The 1000 Genomes Project is an ongoing consortium designed to deliver whole genome sequence information from an ethnically diverse population and, therefore, is a rich source to determine both common and rare genetic variants. METHODS AND RESULTS We queried the 1000 Genomes Project database of 1092 individuals for exonic variants within 3 sarcomere genes MHY7, MYBPC3, and TTN. We focused our analysis on protein-altering variation, including nonsynonymous single nucleotide polymorphisms, insertion/deletion polymorphisms, or splice site altering variants. We identified known and predicted pathogenic variation in MYBPC3 and MYH7 at a higher frequency than what would be expected based on the known prevalence of cardiomyopathy. We also found substantial variation, including protein-disrupting sequences, in TTN. CONCLUSIONS Cardiomyopathy is a genetically heterogeneous disorder caused by mutations in multiple genes. The frequency of predicted pathogenic protein-altering variation in cardiomyopathy genes suggests that many of these variants may be insufficient to cause disease on their own but may modify phenotype in a genetically susceptible host. This is suggested by the high prevalence of TTN insertion/deletions in the 1000 Genomes Project cohort. Given the possibility of additional genetic variants that modify the phenotype of a primary driver mutation, broad-based genetic testing should be employed.
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Affiliation(s)
- Jessica R Golbus
- Department of Medicine and Department of Human Genetics, The University of Chicago, Chicago, IL 60637, USA
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Suzuki T, Shioya T, Murayama T, Sugihara M, Odagiri F, Nakazato Y, Nishizawa H, Chugun A, Sakurai T, Daida H, Morimoto S, Kurebayashi N. Multistep ion channel remodeling and lethal arrhythmia precede heart failure in a mouse model of inherited dilated cardiomyopathy. PLoS One 2012; 7:e35353. [PMID: 22514734 PMCID: PMC3325934 DOI: 10.1371/journal.pone.0035353] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2011] [Accepted: 03/14/2012] [Indexed: 01/06/2023] Open
Abstract
BACKGROUND Patients with inherited dilated cardiomyopathy (DCM) frequently die with severe heart failure (HF) or die suddenly with arrhythmias, although these symptoms are not always observed at birth. It remains unclear how and when HF and arrhythmogenic changes develop in these DCM mutation carriers. In order to address this issue, properties of the myocardium and underlying gene expressions were studied using a knock-in mouse model of human inherited DCM caused by a deletion mutation ΔK210 in cardiac troponinT. METHODOLOGY/PRINCIPAL FINDINGS By 1 month, DCM mice had already enlarged hearts, but showed no symptoms of HF and a much lower mortality than at 2 months or later. At around 2 months, some would die suddenly with no clear symptoms of HF, whereas at 3 months, many of the survivors showed evident symptoms of HF. In isolated left ventricular myocardium (LV) from 2 month-mice, spontaneous activity frequently occurred and action potential duration (APD) was prolonged. Transient outward (I(to)) and ultrarapid delayed rectifier K(+) (I(Kur)) currents were significantly reduced in DCM myocytes. Correspondingly, down-regulation of Kv4.2, Kv1.5 and KChIP2 was evident in mRNA and protein levels. In LVs at 3-months, more frequent spontaneous activity, greater prolongation of APD and further down-regulation in above K(+) channels were observed. At 1 month, in contrast, infrequent spontaneous activity and down-regulation of Kv4.2, but not Kv1.5 or KChIP2, were observed. CONCLUSIONS/SIGNIFICANCE Our results suggest that at least three steps of electrical remodeling occur in the hearts of DCM model mice, and that the combined down-regulation of Kv4.2, Kv1.5 and KChIP2 prior to the onset of HF may play an important role in the premature sudden death in this DCM model. DCM mice at 1 month or before, on the contrary, are associated with low risk of death in spite of inborn disorder and enlarged heart.
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Affiliation(s)
- Takeshi Suzuki
- Department of Cellular and Molecular Pharmacology, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo, Japan
- Department of Cardiovascular Medicine, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo, Japan
| | - Takao Shioya
- Department of Physiology, Faculty of Medicine, Saga University, Saga, Japan
| | - Takashi Murayama
- Department of Cellular and Molecular Pharmacology, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo, Japan
| | - Masami Sugihara
- Department of Cellular and Molecular Pharmacology, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo, Japan
- Department of Cardiovascular Medicine, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo, Japan
| | - Fuminori Odagiri
- Department of Cellular and Molecular Pharmacology, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo, Japan
- Department of Cardiovascular Medicine, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo, Japan
| | - Yuji Nakazato
- Department of Cardiovascular Medicine, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo, Japan
| | - Hiroto Nishizawa
- Department of Cellular and Molecular Pharmacology, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo, Japan
- Department of Cardiovascular Medicine, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo, Japan
| | - Akihito Chugun
- Department of Cellular and Molecular Pharmacology, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo, Japan
| | - Takashi Sakurai
- Department of Cellular and Molecular Pharmacology, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo, Japan
| | - Hiroyuki Daida
- Department of Cardiovascular Medicine, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo, Japan
| | - Sachio Morimoto
- Department of Clinical Pharmacology, Faculty of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Nagomi Kurebayashi
- Department of Cellular and Molecular Pharmacology, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo, Japan
- * E-mail:
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