1
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Ngkelo A, Richart A, Kirk JA, Bonnin P, Vilar J, Lemitre M, Marck P, Branchereau M, Le Gall S, Renault N, Guerin C, Ranek MJ, Kervadec A, Danelli L, Gautier G, Blank U, Launay P, Camerer E, Bruneval P, Menasche P, Heymes C, Luche E, Casteilla L, Cousin B, Rodewald HR, Kass DA, Silvestre JS. Mast cells regulate myofilament calcium sensitization and heart function after myocardial infarction. J Exp Med 2017; 213:1353-74. [PMID: 27353089 PMCID: PMC4925026 DOI: 10.1084/jem.20160081] [Citation(s) in RCA: 90] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2016] [Accepted: 05/12/2016] [Indexed: 11/24/2022] Open
Abstract
Ngkelo et al. use a mast cell–deficient mouse model to reveal a protective role of mast cells in myocardial infarction, through regulation of the cardiac contractile machinery. Acute myocardial infarction (MI) is a severe ischemic disease responsible for heart failure and sudden death. Inflammatory cells orchestrate postischemic cardiac remodeling after MI. Studies using mice with defective mast/stem cell growth factor receptor c-Kit have suggested key roles for mast cells (MCs) in postischemic cardiac remodeling. Because c-Kit mutations affect multiple cell types of both immune and nonimmune origin, we addressed the impact of MCs on cardiac function after MI, using the c-Kit–independent MC-deficient (Cpa3Cre/+) mice. In response to MI, MC progenitors originated primarily from white adipose tissue, infiltrated the heart, and differentiated into mature MCs. MC deficiency led to reduced postischemic cardiac function and depressed cardiomyocyte contractility caused by myofilament Ca2+ desensitization. This effect correlated with increased protein kinase A (PKA) activity and hyperphosphorylation of its targets, troponin I and myosin-binding protein C. MC-specific tryptase was identified to regulate PKA activity in cardiomyocytes via protease-activated receptor 2 proteolysis. This work reveals a novel function for cardiac MCs modulating cardiomyocyte contractility via alteration of PKA-regulated force–Ca2+ interactions in response to MI. Identification of this MC-cardiomyocyte cross-talk provides new insights on the cellular and molecular mechanisms regulating the cardiac contractile machinery and a novel platform for therapeutically addressable regulators.
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Affiliation(s)
- Anta Ngkelo
- Institut National de la Santé et de la Recherche Médicale (INSERM), UMRS-970, Centre de Recherche Cardiovasculaire, Université Paris Descartes, Sorbonne Paris Cité, F-75015 Paris, France
| | - Adèle Richart
- Institut National de la Santé et de la Recherche Médicale (INSERM), UMRS-970, Centre de Recherche Cardiovasculaire, Université Paris Descartes, Sorbonne Paris Cité, F-75015 Paris, France
| | - Jonathan A Kirk
- Division of Cardiology, Johns Hopkins Medical Institutions, Baltimore, MD 212015
| | - Philippe Bonnin
- INSERM, U965, Hôpital Lariboisière-Fernand-Widal, Assistance Publique Hôpitaux de Paris, F-75010 Paris, France
| | - Jose Vilar
- Institut National de la Santé et de la Recherche Médicale (INSERM), UMRS-970, Centre de Recherche Cardiovasculaire, Université Paris Descartes, Sorbonne Paris Cité, F-75015 Paris, France
| | - Mathilde Lemitre
- Institut National de la Santé et de la Recherche Médicale (INSERM), UMRS-970, Centre de Recherche Cardiovasculaire, Université Paris Descartes, Sorbonne Paris Cité, F-75015 Paris, France
| | - Pauline Marck
- INSERM, UMR-1048, Institut des Maladies Métaboliques et Cardiovasculaires, F-31004 Toulouse, France
| | - Maxime Branchereau
- INSERM, UMR-1048, Institut des Maladies Métaboliques et Cardiovasculaires, F-31004 Toulouse, France
| | - Sylvain Le Gall
- Institut National de la Santé et de la Recherche Médicale (INSERM), UMRS-970, Centre de Recherche Cardiovasculaire, Université Paris Descartes, Sorbonne Paris Cité, F-75015 Paris, France
| | - Nisa Renault
- Institut National de la Santé et de la Recherche Médicale (INSERM), UMRS-970, Centre de Recherche Cardiovasculaire, Université Paris Descartes, Sorbonne Paris Cité, F-75015 Paris, France
| | - Coralie Guerin
- National Cytometry Platform, Department of Infection and Immunity, Luxembourg Institute of Health, L-4354 Esch-sur-Alzette, Luxembourg
| | - Mark J Ranek
- Division of Cardiology, Johns Hopkins Medical Institutions, Baltimore, MD 212015
| | - Anaïs Kervadec
- Institut National de la Santé et de la Recherche Médicale (INSERM), UMRS-970, Centre de Recherche Cardiovasculaire, Université Paris Descartes, Sorbonne Paris Cité, F-75015 Paris, France
| | - Luca Danelli
- Laboratoire d'Excellence INFLAMEX, Université Paris Diderot, Sorbonne Paris Cité, F-75018 Paris, France INSERM, U1149, F-75018 Paris, France Centre National de la Recherche Scientifique (CNRS) ERL 8252, F-75018 Paris, France
| | - Gregory Gautier
- Laboratoire d'Excellence INFLAMEX, Université Paris Diderot, Sorbonne Paris Cité, F-75018 Paris, France INSERM, U1149, F-75018 Paris, France
| | - Ulrich Blank
- Laboratoire d'Excellence INFLAMEX, Université Paris Diderot, Sorbonne Paris Cité, F-75018 Paris, France INSERM, U1149, F-75018 Paris, France Centre National de la Recherche Scientifique (CNRS) ERL 8252, F-75018 Paris, France
| | - Pierre Launay
- Laboratoire d'Excellence INFLAMEX, Université Paris Diderot, Sorbonne Paris Cité, F-75018 Paris, France INSERM, U1149, F-75018 Paris, France
| | - Eric Camerer
- Institut National de la Santé et de la Recherche Médicale (INSERM), UMRS-970, Centre de Recherche Cardiovasculaire, Université Paris Descartes, Sorbonne Paris Cité, F-75015 Paris, France
| | - Patrick Bruneval
- Institut National de la Santé et de la Recherche Médicale (INSERM), UMRS-970, Centre de Recherche Cardiovasculaire, Université Paris Descartes, Sorbonne Paris Cité, F-75015 Paris, France Hôpital European George Pompidou, Assistance Publique Hôpitaux de Paris, F-75015 Paris, France
| | - Philippe Menasche
- Institut National de la Santé et de la Recherche Médicale (INSERM), UMRS-970, Centre de Recherche Cardiovasculaire, Université Paris Descartes, Sorbonne Paris Cité, F-75015 Paris, France Hôpital European George Pompidou, Assistance Publique Hôpitaux de Paris, F-75015 Paris, France
| | - Christophe Heymes
- INSERM, UMR-1048, Institut des Maladies Métaboliques et Cardiovasculaires, F-31004 Toulouse, France
| | - Elodie Luche
- STROMALab, Etablissement Français du Sang, INSERM U1031, CNRS ERL 5311, Université de Toulouse, F-31004 Toulouse, France
| | - Louis Casteilla
- STROMALab, Etablissement Français du Sang, INSERM U1031, CNRS ERL 5311, Université de Toulouse, F-31004 Toulouse, France
| | - Béatrice Cousin
- STROMALab, Etablissement Français du Sang, INSERM U1031, CNRS ERL 5311, Université de Toulouse, F-31004 Toulouse, France
| | - Hans-Reimer Rodewald
- Division of Cellular Immunology, German Cancer Research Center, D-69120 Heidelberg, Germany
| | - David A Kass
- Division of Cardiology, Johns Hopkins Medical Institutions, Baltimore, MD 212015
| | - Jean-Sébastien Silvestre
- Institut National de la Santé et de la Recherche Médicale (INSERM), UMRS-970, Centre de Recherche Cardiovasculaire, Université Paris Descartes, Sorbonne Paris Cité, F-75015 Paris, France
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2
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Wang Y, Wang S, Lei M, Boyett M, Tsui H, Liu W, Wang X. The p21-activated kinase 1 (Pak1) signalling pathway in cardiac disease: from mechanistic study to therapeutic exploration. Br J Pharmacol 2017; 175:1362-1374. [PMID: 28574147 DOI: 10.1111/bph.13872] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Revised: 05/12/2017] [Accepted: 05/17/2017] [Indexed: 01/01/2023] Open
Abstract
p21-activated kinase 1 (Pak1) is a member of the highly conserved family of serine/threonine protein kinases regulated by Ras-related small G-proteins, Cdc42/Rac1. It has been previously demonstrated to be involved in cardiac protection. Based on recent studies, this review provides an overview of the role of Pak1 in cardiac diseases including disrupted Ca2+ homoeostasis-related cardiac arrhythmias, adrenergic stress- and pressure overload-induced hypertrophy, and ischaemia/reperfusion injury. These findings demonstrate the important role of Pak1 mediated through the phosphorylation and transcriptional modification of hypertrophy and/or arrhythmia-related genes. This review also discusses the anti-arrhythmic and anti-hypertrophic, protective function of Pak1 and the beneficial effects of fingolimod (an FDA-approved sphingolipid drug), a Pak1 activator, and its ability to prevent arrhythmias and cardiac hypertrophy. These findings also highlight the therapeutic potential of Pak1 signalling in the treatment and prevention of cardiac diseases. LINKED ARTICLES This article is part of a themed section on Spotlight on Small Molecules in Cardiovascular Diseases. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.8/issuetoc.
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Affiliation(s)
- Yanwen Wang
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK
| | - Shunyao Wang
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK
| | - Ming Lei
- Department of Pharmacology, The University of Oxford, Oxford, UK
| | - Mark Boyett
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK
| | - Hoyee Tsui
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK
| | - Wei Liu
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK
| | - Xin Wang
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK
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3
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Biesiadecki BJ, Ziolo MT. Should we treat heart failure with phosphatase inhibitors? Better to start at the end. J Mol Cell Cardiol 2015; 89:116-8. [PMID: 26497613 DOI: 10.1016/j.yjmcc.2015.10.020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Revised: 10/16/2015] [Accepted: 10/19/2015] [Indexed: 01/21/2023]
Affiliation(s)
- Brandon J Biesiadecki
- Department of Physiology and Cell Biology, Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA.
| | - Mark T Ziolo
- Department of Physiology and Cell Biology, Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA
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4
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Carley AN, Taglieri DM, Bi J, Solaro RJ, Lewandowski ED. Metabolic efficiency promotes protection from pressure overload in hearts expressing slow skeletal troponin I. Circ Heart Fail 2014; 8:119-27. [PMID: 25424393 DOI: 10.1161/circheartfailure.114.001496] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
BACKGROUND The failing heart displays increased glycolytic flux that is not matched by a commensurate increase in glucose oxidation. This mismatch induces increased anaplerotic flux and inefficient glucose metabolism. We previously found adult transgenic mouse hearts expressing the fetal troponin I isoform, (ssTnI) to be protected from ischemia by increased glycolysis. In this study, we investigated the metabolic response of adult mouse hearts expressing ssTnI to chronic pressure overload. METHODS AND RESULTS At 2 to 3 months of age, ssTnI mice or their nontransgenic littermates underwent aortic constriction (TAC). TAC induced a 25% increase in nontransgenic heart size but only a 7% increase in ssTnI hearts (P<0.05). Nontransgenic TAC developed diastolic dysfunction (65% increase in E/A ratio), whereas the E/A ratio actually decreased in ssTnI TAC. Isolated perfused hearts from nontransgenic TAC mice showed reduced cardiac function and reduced creatine phosphate:ATP (16% reduction), but ssTnI TAC hearts maintained cardiac function and energy charge. Contrasting nontransgenic TAC, ssTnI TAC significantly increased glucose oxidation at the expense of palmitate oxidation, preventing the increase in anaplerosis observed in nontransgenic TAC hearts. Elevated glucose oxidation was mediated by a reduction in pyruvate dehydrogenase kinase 4 expression, enabling pyruvate dehydrogenase to compete against anaplerotic enzymes for pyruvate carboxylation. CONCLUSIONS Expression of a single fetal myofilament protein into adulthood in the ssTnI-transgenic mouse heart induced downregulation of the gene expression response for pyruvate dehydrogenase kinase to pressure overload. The consequence of elevated pyruvate oxidation in ssTnI during TAC reduced anaplerotic flux, ameliorating inefficiencies in glucose oxidation, with energetic and functional protection against cardiac decompensation.
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Affiliation(s)
- Andrew N Carley
- From the Center for Cardiovascular Research and Department of Physiology and Biophysics, University of Illinois at Chicago College of Medicine
| | - Domenico M Taglieri
- From the Center for Cardiovascular Research and Department of Physiology and Biophysics, University of Illinois at Chicago College of Medicine
| | - Jian Bi
- From the Center for Cardiovascular Research and Department of Physiology and Biophysics, University of Illinois at Chicago College of Medicine
| | - R John Solaro
- From the Center for Cardiovascular Research and Department of Physiology and Biophysics, University of Illinois at Chicago College of Medicine
| | - E Douglas Lewandowski
- From the Center for Cardiovascular Research and Department of Physiology and Biophysics, University of Illinois at Chicago College of Medicine.
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5
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Nixon BR, Walton SD, Zhang B, Brundage EA, Little SC, Ziolo MT, Davis JP, Biesiadecki BJ. Combined troponin I Ser-150 and Ser-23/24 phosphorylation sustains thin filament Ca(2+) sensitivity and accelerates deactivation in an acidic environment. J Mol Cell Cardiol 2014; 72:177-85. [PMID: 24657721 PMCID: PMC4075059 DOI: 10.1016/j.yjmcc.2014.03.010] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/01/2013] [Revised: 03/10/2014] [Accepted: 03/13/2014] [Indexed: 01/09/2023]
Abstract
The binding of Ca(2+) to troponin C (TnC) in the troponin complex is a critical step regulating the thin filament, the actin-myosin interaction and cardiac contraction. Phosphorylation of the troponin complex is a key regulatory mechanism to match cardiac contraction to demand. Here we demonstrate that phosphorylation of the troponin I (TnI) subunit is simultaneously increased at Ser-150 and Ser-23/24 during in vivo myocardial ischemia. Myocardial ischemia decreases intracellular pH resulting in depressed binding of Ca(2+) to TnC and impaired contraction. To determine the pathological relevance of these simultaneous TnI phosphorylations we measured individual TnI Ser-150 (S150D), Ser-23/24 (S23/24D) and combined (S23/24/150D) pseudo-phosphorylation effects on thin filament regulation at acidic pH similar to that in myocardial ischemia. Results demonstrate that while acidic pH decreased thin filament Ca(2+) binding to TnC regardless of TnI composition, TnI S150D attenuated this decrease rendering it similar to non-phosphorylated TnI at normal pH. The dissociation of Ca(2+) from TnC was unaltered by pH such that TnI S150D remained slow, S23/24D remained accelerated and the combined S23/24/150D remained accelerated. This effect of the combined TnI Ser-150 and Ser-23/24 pseudo-phosphorylations to maintain Ca(2+) binding while accelerating Ca(2+) dissociation represents the first post-translational modification of troponin by phosphorylation to both accelerate thin filament deactivation and maintain Ca(2+) sensitive activation. These data suggest that TnI Ser-150 phosphorylation induced attenuation of the pH-dependent decrease in Ca(2+) sensitivity and its combination with Ser-23/24 phosphorylation to maintain accelerated thin filament deactivation may impart an adaptive role to preserve contraction during acidic ischemia pH without slowing relaxation.
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Affiliation(s)
- Benjamin R Nixon
- Department of Physiology and Cell Biology, Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA
| | - Shane D Walton
- Department of Physiology and Cell Biology, Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA
| | - Bo Zhang
- Department of Physiology and Cell Biology, Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA
| | - Elizabeth A Brundage
- Department of Physiology and Cell Biology, Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA
| | - Sean C Little
- Department of Physiology and Cell Biology, Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA
| | - Mark T Ziolo
- Department of Physiology and Cell Biology, Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA
| | - Jonathan P Davis
- Department of Physiology and Cell Biology, Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA
| | - Brandon J Biesiadecki
- Department of Physiology and Cell Biology, Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA.
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6
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Feest ER, Steven Korte F, Tu AY, Dai J, Razumova MV, Murry CE, Regnier M. Thin filament incorporation of an engineered cardiac troponin C variant (L48Q) enhances contractility in intact cardiomyocytes from healthy and infarcted hearts. J Mol Cell Cardiol 2014; 72:219-27. [PMID: 24690333 DOI: 10.1016/j.yjmcc.2014.03.015] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/17/2013] [Revised: 03/03/2014] [Accepted: 03/21/2014] [Indexed: 01/10/2023]
Abstract
Many current pharmaceutical therapies for systolic heart failure target intracellular [Ca(2+)] ([Ca(2+)]i) metabolism, or cardiac troponin C (cTnC) on thin filaments, and can have significant side-effects, including arrhythmias or adverse effects on diastolic function. In this study, we tested the feasibility of directly increasing the Ca(2+) binding properties of cTnC to enhance contraction independent of [Ca(2+)]i in intact cardiomyocytes from healthy and myocardial infarcted (MI) hearts. Specifically, cardiac thin filament activation was enhanced through adenovirus-mediated over-expression of a cardiac troponin C (cTnC) variant designed to have increased Ca(2+) binding affinity conferred by single amino acid substitution (L48Q). In skinned cardiac trabeculae and myofibrils we and others have shown that substitution of L48Q cTnC for native cTnC increases Ca(2+) sensitivity of force and the maximal rate of force development. Here we introduced L48Q cTnC into myofilaments of intact cardiomyocytes via adeno-viral transduction to deliver cDNA for the mutant or wild type (WT) cTnC protein. Using video-microscopy to monitor cell contraction, relaxation, and intracellular Ca(2+) transients (Fura-2), we report that incorporation of L48Q cTnC significantly increased contractility of cardiomyocytes from healthy and MI hearts without adversely affecting Ca(2+) transient properties or relaxation. The improvements in contractility from L48Q cTnC expression are likely the result of enhanced contractile efficiency, as intracellular Ca(2+) transient amplitudes were not affected. Expression and incorporation of L48Q cTnC into myofilaments was confirmed by Western blot analysis of myofibrils from transduced cardiomyocytes, which indicated replacement of 18±2% of native cTnC with L48Q cTnC. These experiments demonstrate the feasibility of directly targeting cardiac thin filament proteins to enhance cardiomyocyte contractility that is impaired following MI.
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Affiliation(s)
- Erik R Feest
- Department of Bioengineering, University of Washington, Seattle. WA 98195, USA
| | - F Steven Korte
- Department of Bioengineering, University of Washington, Seattle. WA 98195, USA; Centers for Cardiovascular Biology, Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA 98109, USA
| | - An-Yue Tu
- Department of Bioengineering, University of Washington, Seattle. WA 98195, USA
| | - Jin Dai
- Department of Bioengineering, University of Washington, Seattle. WA 98195, USA
| | - Maria V Razumova
- Department of Bioengineering, University of Washington, Seattle. WA 98195, USA
| | - Charles E Murry
- Department of Bioengineering, University of Washington, Seattle. WA 98195, USA; Department of Pathology, University of Washington, Seattle, WA 98195, USA; Centers for Cardiovascular Biology, Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA 98109, USA
| | - Michael Regnier
- Department of Bioengineering, University of Washington, Seattle. WA 98195, USA; Centers for Cardiovascular Biology, Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA 98109, USA.
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7
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Kirk JA, Zhang P, Murphy AM, Van Eyk JE. Troponin I alterations detected by multiple-reaction monitoring: how might this impact the study of heart failure? Expert Rev Proteomics 2013; 10:5-8. [PMID: 23414352 DOI: 10.1586/epr.12.77] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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8
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Lai HL, Grachoff M, Marion AL, Khan FF, Warren CM, Chowdhury SA, Wolska BM, Solaro RJ, Geenen DL, Wang QT. Maintenance of adult cardiac function requires the chromatin factor Asxl2. J Mol Cell Cardiol 2012; 53:734-41. [PMID: 23046516 PMCID: PMC3472135 DOI: 10.1016/j.yjmcc.2012.08.014] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/07/2011] [Revised: 08/16/2012] [Accepted: 08/18/2012] [Indexed: 11/17/2022]
Abstract
During development and differentiation, cell type-specific chromatin configurations are set up to facilitate cell type-specific gene expression. Defects in the establishment or the maintenance of the correct chromatin configuration have been associated with diseases ranging from leukemia to muscular dystrophy. The heart expresses many chromatin factors, and we are only beginning to understand their roles in heart development and function. We have previously shown that the chromatin regulator Asxl2 is highly expressed in the murine heart both during development and adulthood. In the absence of Asxl2, there is a significant reduction in trimethylation of histone H3 lysine 27 (H3K27), a histone mark associated with lineage-specific silencing of developmental genes. Here we present evidence that Asxl2 is required for the long-term maintenance of ventricular function and for the maintenance of normal cardiac gene expression. Asxl2(-/-) hearts displayed progressive deterioration of ventricular function. By 10 months of age, there was ~37% reduction in fractional shortening in Asxl2(-/-) hearts compared to wild-type. Analysis of the expression of myofibril proteins suggests that Asxl2 is required for the repression of β-MHC. Asxl2(-/-) hearts did not exhibit hypertrophy, suggesting that the de-repression of β-MHC was not the result of hypertrophic response. Instead, Asxl2 and the histone methyltansferase Ezh2 co-localize to β-MHC promoter, suggesting that Asxl2 directly represses β-MHC. Interrogation of the CardioGenomics database revealed that ASXL2 is down-regulated in the hearts of patients with ischemic or idiopathic dilated cardiomyopathy. We propose that chromatin factors like Asxl2 function in the adult heart to regulate cell type- and stage-specific patterns of gene expression, and the disruption of such regulation may be involved in the etiology and/or development of certain forms of human heart disease.
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MESH Headings
- Animals
- Blood Pressure
- Cardiomyopathy, Dilated/metabolism
- Cardiomyopathy, Dilated/pathology
- Cardiomyopathy, Dilated/physiopathology
- Case-Control Studies
- Cell Size
- Cyclic AMP-Dependent Protein Kinases/metabolism
- Enhancer of Zeste Homolog 2 Protein
- Female
- Gene Expression Regulation
- HEK293 Cells
- Humans
- Male
- Mice
- Mice, 129 Strain
- Mice, Inbred C57BL
- Mice, Knockout
- Myocardium/enzymology
- Myocardium/metabolism
- Myocardium/pathology
- Myocytes, Cardiac/enzymology
- Myocytes, Cardiac/metabolism
- Myocytes, Cardiac/physiology
- Myosin Heavy Chains/genetics
- Myosin Heavy Chains/metabolism
- Phosphorylation
- Polycomb Repressive Complex 2/metabolism
- Promoter Regions, Genetic
- Protein Processing, Post-Translational
- Repressor Proteins/genetics
- Repressor Proteins/metabolism
- Signal Transduction
- Stroke Volume
- Troponin I/metabolism
- Ventricular Function
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Affiliation(s)
- Hsiao-Lei Lai
- Department of Biological Sciences, University of Illinois at Chicago, 900 S Ashland Ave., Chicago, IL 60607, USA
| | - Milana Grachoff
- Department of Medicine, Section of Cardiology and the Center for Cardiovascular Research, University of Illinois at Chicago, 840 S Wood Street, Chicago, IL 60612, USA
| | - Andrea L. Marion
- Department of Biological Sciences, University of Illinois at Chicago, 900 S Ashland Ave., Chicago, IL 60607, USA
| | - Farida F. Khan
- Department of Biological Sciences, University of Illinois at Chicago, 900 S Ashland Ave., Chicago, IL 60607, USA
| | - Chad M. Warren
- Department of Physiology and Biophysics, Center for Cardiovascular Research, College of Medicine, University of Illinois at Chicago, 835 S. Wolcott Ave, Chicago, IL 60612-7342, USA
| | - Shamim A.K. Chowdhury
- Department of Medicine, Section of Cardiology and the Center for Cardiovascular Research, University of Illinois at Chicago, 840 S Wood Street, Chicago, IL 60612, USA
| | - Beata M. Wolska
- Department of Medicine, Section of Cardiology and the Center for Cardiovascular Research, University of Illinois at Chicago, 840 S Wood Street, Chicago, IL 60612, USA
| | - R. John Solaro
- Department of Physiology and Biophysics, Center for Cardiovascular Research, College of Medicine, University of Illinois at Chicago, 835 S. Wolcott Ave, Chicago, IL 60612-7342, USA
| | - David L. Geenen
- Department of Medicine, Section of Cardiology and the Center for Cardiovascular Research, University of Illinois at Chicago, 840 S Wood Street, Chicago, IL 60612, USA
| | - Q. Tian Wang
- Department of Biological Sciences, University of Illinois at Chicago, 900 S Ashland Ave., Chicago, IL 60607, USA
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9
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Zhang L, Song Z, Chang H, Wang YY, Yu ZB. Enhanced N-terminal degradation of troponin I blunts cardiac function responsiveness to isoproterenol in 4-week tail-suspended rats. Mol Med Rep 2012; 7:271-9. [PMID: 23042367 DOI: 10.3892/mmr.2012.1119] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2012] [Accepted: 10/01/2012] [Indexed: 11/05/2022] Open
Abstract
The N-terminal extension of cardiac troponin I (cTnI) is important in regulating cardiac function. Although the normal rat myocardium shows some cTnI N-terminal degradation (cTnI-ND), exposure to 4 weeks of tail-suspension markedly increased cTnI-ND. We hypothesized that the increased cTnI-ND in tail-suspended rats may affect cardiac function, particularly during β-adrenergic (β-A) stimulation. The increase in cardiac output with isoproterenol (ISO) treatment was smaller in tail-suspended rats compared with controls. Left ventricular end-diastolic pressure was elevated and increases in maximal rates of left ventricular pressure development and relaxation were lower during ISO treatment in tail-suspended rats. Response to ISO, forskolin, DB-cAMP and IBMX was also lower in cardiomyocytes from tail-suspended rats. The increase in shortening and re-lengthening the rates of cardiomyocytes at a maximal dose of ISO, forskolin, DB-cAMP and IBMX treatment was limited in tail-suspended rats. There was no difference in Ca2+ sensitivity of the isometric force between tail-suspended and control rats, although Ca2+ sensitivity was decreased less in tail-suspended rats versus control rats during PKA phosphorylation. There was no difference in PKA protein expression and activation during ISO stimulation between the two groups. Due to the increase in cTnI-ND, ISO-induced phosphorylation of cTnI was reduced in tail-suspended rats. The total phospholamban expression and phosphorylation by ISO was unaltered in tail-suspended rat hearts. These data suggest that enhanced cTnI-ND following 4-week tail-suspension is a major component of the β-A receptor signaling pathway, depressing cardiac function under ISO stimulation.
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Affiliation(s)
- Lin Zhang
- Department of Aerospace Physiology, Fourth Military Medical University, Xi'an 710032, PR China
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10
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Ford SJ, Chandra M. The effects of slow skeletal troponin I expression in the murine myocardium are influenced by development-related shifts in myosin heavy chain isoform. J Physiol 2012; 590:6047-63. [PMID: 22966157 DOI: 10.1113/jphysiol.2012.240085] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Troponin I (TnI) and myosin heavy chain (MHC) are two contractile regulatory proteins that undergo major shifts in isoform expression as cardiac myocytes mature from embryonic to adult stages. To date, many studies have investigated individual effects of embryonic vs. cardiac isoforms of either TnI or MHC on cardiac muscle function and contractile dynamics. Thus, we sought to determine whether concomitant expression of the embryonic isoforms of both TnI and MHC had functional effects that were not previously observed. Adult transgenic (TG) mice that express the embryonic isoform of TnI, slow skeletal TnI (ssTnI), were treated with propylthiouracil (PTU) to revert MHC expression from adult (α-MHC) to embryonic (β-MHC) isoforms. Cardiac muscle fibres from these mice contained ∼80% β-MHC and ∼34% ssTnI of total MHC or TnI, respectively, allowing us to test the functional effects of ssTnI in the presence of β-MHC. Detergent-skinned cardiac muscle fibre bundles were used to study how the interplay between MHC and TnI modulate muscle length-mediated effect on crossbridge (XB) recruitment dynamics, Ca(2+)-activated tension, and ATPase activity. One major finding was that the model-predicted XB recruitment rate (b) was enhanced significantly by ssTnI, and this speeding effect of ssTnI on XB recruitment rate was much greater (3.8-fold) when β-MHC was present. Another major finding was that the previously documented ssTnI-mediated increase in myofilament Ca(2+) sensitivity (pCa(50)) was blunted when β-MHC was present. ssTnI expression increased pCa(50) by 0.33 in α-MHC fibres, whereas ssTnI increased pCa(50) by only 0.05 in β-MHC fibres. Our study provides new evidence for significant interplay between MHC and TnI isoforms that is essential for tuning cardiac contractile function. Thus, MHC-TnI interplay may provide a developmentally dependent mechanism to enhance XB recruitment dynamics at a time when Ca(2+)-handling mechanisms are underdeveloped, and to prevent excessive ssTnI-dependent inotropy (increased Ca(2+) sensitivity) in the embryonic myocardium.
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Affiliation(s)
- Steven J Ford
- Department of Veterinary and Comparative Anatomy, Pharmacology, and Physiology (VCAPP), Washington State University, Pullman, WA 99164, USA.
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11
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Abstract
Berbamine (BM), a natural compound derived from Berberis vulgaris L, has been reported to inhibit cardiac contractile function at higher concentrations. Here, we report that BM had concentration-dependent biphasic effects on myocardial contraction in Langendorff-perfused rat hearts, that is, at lower concentrations (30-100 nM), it displayed positive inotropic and lusitropic effects, whereas at a higher concentration of 1 μM, it caused a negative inotropic effect after an initially weak increase. These effects were further confirmed in cardiomyocytes isolated from the left ventricles of rats. Moreover, the increased cell shortening by BM at concentrations from 0.1 to 100 nM was not associated with an alteration of intracellular Ca transients. Consistently, at 30 nM, BM shifted the cell shortening--Ca transient relationship curve induced by cumulative elevation of extracellular Ca concentration to the left. Furthermore, BM significantly increased membrane-bound but not filament-bound protein kinase C epsilon (PKCε) in the isolated hearts and cardiomyocytes. Such a translocation was inhibited by PKCε-specific inhibitor PKCε V1-2 concomitant with the abolishment of the BM-induced increase in contraction. These findings reveal the positive inotropic effect of BM in the myocardium and demonstrate that BM increases myocardial contractility by increasing myofilament Ca sensitivity via a PKCε-dependent signaling pathway.
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12
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Yang FH, Pyle WG. Reduced cardiac CapZ protein protects hearts against acute ischemia–reperfusion injury and enhances preconditioning. J Mol Cell Cardiol 2012; 52:761-72. [DOI: 10.1016/j.yjmcc.2011.11.013] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/24/2011] [Revised: 11/17/2011] [Accepted: 11/21/2011] [Indexed: 10/14/2022]
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13
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Monasky MM, Taglieri DM, Patel BG, Chernoff J, Wolska BM, Ke Y, Solaro RJ. p21-activated kinase improves cardiac contractility during ischemia-reperfusion concomitant with changes in troponin-T and myosin light chain 2 phosphorylation. Am J Physiol Heart Circ Physiol 2011; 302:H224-30. [PMID: 22037191 DOI: 10.1152/ajpheart.00612.2011] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
p21-activated kinase 1 (Pak1) is a serine/threonine kinase that activates protein phosphatase 2a, resulting in the dephosphorylation of cardiac proteins and increased myofilament Ca(2+) sensitivity. Emerging evidence indirectly indicates a role for Pak1 in ischemia-reperfusion (I/R), but direct evidence is lacking. We hypothesize that activation of the Pak1 signaling pathway is a cardioprotective mechanism that prevents or reverses the detrimental effects of ischemic injury by inducing posttranslational modifications in myofilament proteins that ultimately improve cardiac contractility following ischemic insult. In the present study, we subjected ex vivo hearts from wild-type (WT) and Pak1-knockout (KO) mice to 20 min of global cardiac ischemia followed by 30 min of reperfusion. In the absence of Pak1, there was an exacerbation of the increased end-diastolic pressure and reduced left ventricular developed pressure occurring after I/R injury. ProQ analysis revealed an increase in troponin-T phosphorylation at baseline in Pak1-KO hearts compared with WT. Significantly decreased myosin light chain 2 (MLC2) phosphorylation in Pak1-KO hearts compared with WT after I/R injury was confirmed by Western immunoblotting. These data indicate that Pak1-KO hearts have reduced recovery of myocardial performance after global I/R injury concomitant with changes in troponin-T and MLC2 phosphorylation. Finally, a protein-protein association between Pak1 and MLC2, and Pak1 and troponin-T, was determined by coimmunoprecipitation. Thus, results of our study provide a basis for targeting a novel pathway, including Pak1, in the therapies for patients with ischemic events.
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Affiliation(s)
- Michelle M Monasky
- Department of Physiology and Biophysics, College of Medicine, University of Illinois at Chicago, 60612-7342, USA
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14
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Pound KM, Arteaga GM, Fasano M, Wilder T, Fischer SK, Warren CM, Wende AR, Farjah M, Abel ED, Solaro RJ, Lewandowski ED. Expression of slow skeletal TnI in adult mouse hearts confers metabolic protection to ischemia. J Mol Cell Cardiol 2011; 51:236-43. [PMID: 21640727 DOI: 10.1016/j.yjmcc.2011.05.014] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/04/2011] [Revised: 04/26/2011] [Accepted: 05/14/2011] [Indexed: 12/30/2022]
Abstract
Changes in metabolic and myofilament phenotypes coincide in developing hearts. Posttranslational modification of sarcomere proteins influences contractility, affecting the energetic cost of contraction. However, metabolic adaptations to sarcomeric phenotypes are not well understood, particularly during pathophysiological stress. This study explored metabolic adaptations to expression of the fetal, slow skeletal muscle troponin I (ssTnI). Hearts expressing ssTnI exhibited no significant ATP loss during 5 min of global ischemia, while non-transgenic littermates (NTG) showed continual ATP loss. At 7 min ischemia TG-ssTnI hearts retained 80±12% of ATP versus 49±6% in NTG (P<0.05). Hearts expressing ssTnI also had increased AMPK phosphorylation. The mechanism of ATP preservation was augmented glycolysis. Glycolytic end products (lactate and alanine) were 38% higher in TG-ssTnI than NTG at 2 min and 27% higher at 5 min. This additional glycolysis was supported exclusively by exogenous glucose, and not glycogen. Thus, expression of a fetal myofilament protein in adult mouse hearts induced elevated anaerobic ATP production during ischemia via metabolic adaptations consistent with the resistance to hypoxia of fetal hearts. The general findings hold important relevance to both our current understanding of the association between metabolic and contractile phenotypes and the potential for invoking cardioprotective mechanisms against ischemic stress. This article is part of a Special Issue entitled "Possible Editorial".
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Affiliation(s)
- Kayla M Pound
- Program in Integrative Cardiac Metabolism, Center for Cardiovascular Research and Department of Physiology and Biophysics, University of Illinois at Chicago, College of Medicine, Chicago, IL 60612, USA
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15
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Shioura KM, Farjah M, Geenen DL, Solaro RJ, Goldspink PH. Myofilament calcium sensitization delays decompensated hypertrophy differently between the sexes following myocardial infarction. Am J Physiol Regul Integr Comp Physiol 2010; 300:R361-8. [PMID: 21106909 DOI: 10.1152/ajpregu.00321.2010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Contractile dysfunction is common to many forms of cardiovascular disease. Approaches directed at enhancing cardiac contractility at the level of the myofilaments during heart failure (HF) may provide a means to improve overall cardiovascular function. We are interested in gender-based differences in cardiac function and the effect of sarcomere activation agents that increase contractility. Thus, we studied the effect of gender and time on integrated arterial-ventricular function (A-V relationship) following myocardial infarction (MI). In addition, transgenic mice that overexpress the slow skeletal troponin I isoform were used to determine the impact of increased myofilament Ca(2+) sensitivity following MI. Based on pressure-volume (P-V) loop measurements, we used derived parameters of cardiovascular function to reveal the effects of sex, time, and increased myofilament Ca(2+) sensitivity among groups of post-MI mice. Analysis of the A-V relationship revealed that the initial increase was similar between the sexes, but the vascular unloading of the heart served to delay the decompensated stage in females. Conversely, the vascular response at 6 and 10 wk post-MI in males contributed to the continuous decline in cardiovascular function. Increasing the myofilament Ca(2+) sensitivity appeared to provide sufficient contractile support to improve contractile function in both male and female transgenic mice. However, the improved contractile function was more beneficial in males as the concurrent vascular response contributed to a delayed decompensated stage in female transgenic mice post-MI. This study represents a quantitative approach to integrating the vascular-ventricular relationship to provide meaningful and diagnostic value following MI. Consequently, the data provide a basis for understanding how the A-V relationship is coupled between males and females and the enhanced ability of the cardiovascular system to tolerate pathophysiological stresses associated with HF in females.
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Affiliation(s)
- Krystyna M Shioura
- Department of Medicine, Section of Cardiology, University of Illinois at Chicago, Chicago, Illinois, USA
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16
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Turner I, Belema-Bedada F, Martindale J, Townsend D, Wang W, Palpant N, Yasuda SC, Barnabei M, Fomicheva E, Metzger JM. Molecular cardiology in translation: gene, cell and chemical-based experimental therapeutics for the failing heart. J Cardiovasc Transl Res 2010; 1:317-27. [PMID: 19956787 DOI: 10.1007/s12265-008-9065-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Acquired and inherited diseases of the heart represent a major health care issue in this country and throughout the World. Clinical medicine has made important advancements in the past quarter century to enable several effective treatment regimes for cardiac patients. Nevertheless, it is apparent that even with the best care, current treatment strategies and therapeutics are inadequate for treating heart disease, leaving it arguably the most pressing health issue today. In this context it is important to seek new approaches to redress the functional deficits in failing myocardium. This review focuses on several recent gene, cell and chemical-based experimental therapeutics currently being developed in the laboratory for potential translation to patient care. For example, new advances in bio-sensing inducible gene expression systems offer the potential for designer cardio-protective proteins to be expressed only during hypoxia/ischemia in the heart. Stem cells continue to offer the promise of cardiac repair, and some recent advances are discussed here. In addition, discovery and applications of synthetic polymers are presented as a chemical-based strategy for acute and chronic treatment of diseased and failing cardiac tissue. Collectively, these approaches serve as the front lines in basic biomedical research, with an eye toward translation of these findings to clinically meaningful applications in cardiac disease.
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Affiliation(s)
- Immanuel Turner
- Department of Integrative Biology & Physiology, University of Minnesota, Medical School, 6-125 Jackson Hall, 321 Church Street SE, Minneapolis, MN 55455, USA
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17
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Sarcomere control mechanisms and the dynamics of the cardiac cycle. J Biomed Biotechnol 2010; 2010:105648. [PMID: 20467475 PMCID: PMC2866969 DOI: 10.1155/2010/105648] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2009] [Accepted: 03/01/2010] [Indexed: 11/18/2022] Open
Abstract
This review focuses on recent developments in the molecular mechanisms by which Ca activates cardiac sarcomeres and how these mechanisms play out in the cardiac cycle. I emphasize the role of mechanisms intrinsic to the sarcomeres as significant determinants of systolic elastance and ventricular stiffening during ejection. Data are presented supporting the idea that processes intrinsic to the thin filaments may promote cooperative activation of the sarcomeres and be an important factor in maintaining and modifying systolic elastance. Application of these ideas to translational medicine and rationale drug design forms an important rationale for detailed understanding of these processes.
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18
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Duke LS, Garcia-Cazarin ML, Sumandea CA, Sievert GA, Balke CW, Zhan DY, Morimoto S, Sumandea MP. Cardiomyopathy-causing deletion K210 in cardiac troponin T alters phosphorylation propensity of sarcomeric proteins. J Mol Cell Cardiol 2010; 48:934-42. [PMID: 20079745 PMCID: PMC2854196 DOI: 10.1016/j.yjmcc.2010.01.005] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2009] [Revised: 01/04/2010] [Accepted: 01/05/2010] [Indexed: 10/19/2022]
Abstract
Ca(2+) desensitization of myofilaments is indicated as a primary mechanism for the pathogenesis of familial dilated cardiomyopathy (DCM) associated with the deletion of lysine 210 (DeltaK210) in cardiac troponin T (cTnT). DeltaK210 knock-in mice closely recapitulate the clinical phenotypes documented in patients with this mutation. Considerable evidence supports the proposition that phosphorylation of cardiac sarcomeric proteins is a key modulator of function and may exacerbate the effect of the deletion. In this study we investigate the impact of K210 deletion on phosphorylation propensity of sarcomeric proteins. Analysis of cardiac myofibrils isolated from DeltaK210 hearts identified a decrease in phosphorylation of cTnI (46%), cTnT (30%) and MyBP-C (32%) compared with wild-type controls. Interestingly, immunoblot analyses with phospho-specific antibodies show augmented phosphorylation of cTnT-Thr(203) (28%) and decreased phosphorylation of cTnI-Ser(23/24) (41%) in mutant myocardium. In vitro kinase assays indicate that DeltaK210 increases phosphorylation propensity of cTnT-Thr(203) three-fold, without changing cTnI-Ser(23/24) phosphorylation. Molecular modeling of cTnT-DeltaK210 structure reveals changes in the electrostatic environment of cTnT helix (residues 203-224) that lead to a more basic environment around Thr(203), which may explain the enhanced PKC-dependent phosphorylation. In addition, yeast two-hybrid assays indicate that cTnT-DeltaK210 binds stronger to cTnI compared with cTnT-wt. Collectively, our observations suggest that cardiomyopathy-causing DeltaK210 has far-reaching effects influencing cTnI-cTnT binding and posttranslational modifications of key sarcomeric proteins.
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Affiliation(s)
- Liliana S. Duke
- Department of Physiology, Center for Muscle Biology, University of Kentucky, Lexington, KY 40536
| | - Mary L. Garcia-Cazarin
- Department of Physiology, Center for Muscle Biology, University of Kentucky, Lexington, KY 40536
| | - C. Amelia Sumandea
- Department of Physiology, Center for Muscle Biology, University of Kentucky, Lexington, KY 40536
| | - Gail A. Sievert
- Department of Physiology, Center for Muscle Biology, University of Kentucky, Lexington, KY 40536
| | - C. William Balke
- Department of Physiology, Center for Muscle Biology, University of Kentucky, Lexington, KY 40536
| | - Dong-Yun Zhan
- Department of Clinical Pharmacology, Kyushu University Graduate School of Medicine, Fukuoka 812-8582, Japan
| | - Sachio Morimoto
- Department of Clinical Pharmacology, Kyushu University Graduate School of Medicine, Fukuoka 812-8582, Japan
| | - Marius P. Sumandea
- Department of Physiology, Center for Muscle Biology, University of Kentucky, Lexington, KY 40536
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19
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Palpant NJ, Houang EM, Delport W, Hastings KEM, Onufriev AV, Sham YY, Metzger JM. Pathogenic peptide deviations support a model of adaptive evolution of chordate cardiac performance by troponin mutations. Physiol Genomics 2010; 42:287-99. [PMID: 20423961 DOI: 10.1152/physiolgenomics.00033.2010] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In cardiac muscle, the troponin (cTn) complex is a key regulator of myofilament calcium sensitivity because it serves as a molecular switch required for translating myocyte calcium fluxes into sarcomeric contraction and relaxation. Studies of several species suggest that ectotherm chordates have myofilaments with heightened calcium responsiveness. However, genetic polymorphisms in cTn that cause increased myofilament sensitivity to activating calcium in mammals result in cardiac disease including arrhythmias, diastolic dysfunction, and increased susceptibility to sudden cardiac death. We hypothesized that specific residue modifications in the regulatory arm of troponin I (TnI) were critical in mediating the observed decrease in myofilament calcium sensitivity within the mammalian taxa. We performed large-scale phylogenetic analysis, atomic resolution molecular dynamics simulations and modeling, and computational alanine scanning. This study provides evidence that a His to Ala substitution within mammalian cardiac TnI (cTnI) reduced the thermodynamic potential at the interface between cTnI and cardiac TnC (cTnC) in the calcium-saturated state by disrupting a strong intermolecular electrostatic interaction. This key residue modification reduced myofilament calcium sensitivity by making cTnI molecularly untethered from cTnC. To meet the requirements for refined mammalian adult cardiac performance, we propose that compensatory evolutionary pressures favored mutations that enhanced the relaxation properties of cTn by decreasing its sensitivity to activating calcium.
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Affiliation(s)
- Nathan J Palpant
- Department of Integrative Biology and Physiology, University of Minnesota Academic Health Center, 321 Church Street SE, Minneapolis, MN 55455, USA
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20
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Ke Y, Sheehan KA, Egom EEA, Lei M, Solaro RJ. Novel bradykinin signaling in adult rat cardiac myocytes through activation of p21-activated kinase. Am J Physiol Heart Circ Physiol 2010; 298:H1283-9. [PMID: 20154261 PMCID: PMC2853422 DOI: 10.1152/ajpheart.01070.2009] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Although bradykinin (BK) is known to exert effects on the myocardium, its intracellular signaling pathways remain poorly understood. Experiments in other cell types indicated that p21-activated kinase-1 (Pak1), a Ser/Thr kinase downstream of small monomeric G proteins, is activated by BK. We previously reported that the expression of active Pak1 in adult cardiac myocytes induced activation of protein phosphatase 2A and dephosphorylation of myofilament proteins (Ke et al. Circ Res 94: 194–200, 2004). In experiments reported here, we tested the hypothesis that BK signals altered protein phosphorylation in adult rat cardiac myocytes through the activation and translocation of Pak1. Treatment of myocytes with BK resulted in the activation of Pak1 as demonstrated by increased autophosphorylation at Thr423 and a diminished striated localization, which is present in the basal state. BK induced dephosphorylation of both cardiac troponin I and phospholamban. Treatment of isolated myocytes with BK also blunted the effect of isoproterenol to enhance peak Ca2+ and relaxation of Ca2+ transients. Protein phosphatase 2A was demonstrated to associate with both Pak 1 and phospholamban. Our studies indicate a novel signaling mechanism for BK in adult rat cardiac myocytes and support our hypothesis that Pak 1 is a significant regulator of phosphatase activity in the heart.
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Affiliation(s)
- Yunbo Ke
- Department of Physiology and Biophysics and Center for Cardiovascular Research, University of Illinois at Chicago, USA
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21
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Sumandea MP, Vahebi S, Sumandea CA, Garcia-Cazarin ML, Staidle J, Homsher E. Impact of cardiac troponin T N-terminal deletion and phosphorylation on myofilament function. Biochemistry 2009; 48:7722-31. [PMID: 19586048 DOI: 10.1021/bi900516n] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Cardiac troponin T (cTnT) is a phosphoprotein that modulates cardiac muscle contraction through its extensive and diverse interactions with neighboring thin filament proteins. Its N-terminal half is the "glue" that anchors the troponin complex to tropomyosin-actin. Until now, studies aimed at investigating the role of the N-terminal tail region have not considered the effects of phosphorylation. To understand better the regulatory role of the N-terminal tail region of phosphorylated cTnT, we investigated the functional effects of N-terminal deletion (amino acids 1-91) and phosphorylation on Ca(2+) dependence of myofilament isometric force production, isometric ATPase rate, and thin filament sliding speed. Chemomechanical profiles were assessed in detergent permeabilized fiber preparations where the native troponin (cTn) was exchanged with recombinant cTn engineered to contain modified cTnT (truncated, phosphorylated) in the presence of wild-type cTnI and cTnC. Removal of the cTnT N-terminal amino acids 1-91 (cTnT-del) enhances myofilament responsiveness to nonsaturating Ca(2+) levels (the physiological range in cardiac myocytes). However, at saturating Ca(2+) levels, there is a reduction in isometric tension and ATPase rate. On one hand, phosphorylation of cTnT-del attenuates the sensitizing effect induced by truncation of the N-terminal tail, "resetting" myofilament Ca(2+) responsiveness back to control levels. On the other hand, it impairs isometric tension development and ATPase rate. Interestingly, phosphorylation of cTnT (cTnT-P) differentially regulates tension cost (an index of cross-bridge cycling rate): increased by cTn-del-P and decreased by intact cTn-wt-P. Like the isometric fiber data, sliding speed of thin filaments regulated by cTn-del is more sensitive to Ca(2+) compared with cTn-wt. Phosphorylation of cTnT (whether cTnT-del or -wt) depresses sliding speed and is associated with Ca(2+) desensitization of thin filament sliding speed.
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Affiliation(s)
- Marius P Sumandea
- Department of Physiology, University of Kentucky, Lexington, Kentucky 40536, USA.
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22
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Venardos KM, Zatta AJ, Marshall T, Ritchie R, Kaye DM. Reduced L-arginine transport contributes to the pathogenesis of myocardial ischemia-reperfusion injury. J Cell Biochem 2009; 108:156-68. [DOI: 10.1002/jcb.22235] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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23
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Ke Y, Lei M, Solaro RJ. Regulation of cardiac excitation and contraction by p21 activated kinase-1. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2009; 98:238-50. [PMID: 19351515 DOI: 10.1016/j.pbiomolbio.2009.01.007] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Cardiac excitation and contraction are regulated by a variety of signaling molecules. Central to the regulatory scheme are protein kinases and phosphatases that carry out reversible phosphorylation of different effectors. The process of beta-adrenergic stimulation mediated by cAMP dependent protein kinase (PKA) forms a well-known pathway considered as the most significant control mechanism in excitation and contraction as well as many other regulatory mechanisms in cardiac function. However, although dephosphorylation pathways are critical to these regulatory processes, signaling to phosphatases is relatively poorly understood. Emerging evidence indicates that regulation of phosphatases, which dampen the effect of beta-adrenergic stimulation, is also important. We review here functional studies of p21 activated kinase-1 (Pak1) and its potential role as an upstream signal for protein phosphatase PP2A in the heart. Pak1 is a serine/threonine protein kinase directly activated by the small GTPases Cdc42 and Rac1. Pak1 is highly expressed in different regions of the heart and modulates the activities of ion channels, sarcomeric proteins, and other phosphoproteins through up-regulation of PP2A activity. Coordination of Pak1 and PP2A activities is not only potentially involved in regulation of normal cardiac function, but is likely to be important in patho-physiological conditions.
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Affiliation(s)
- Yunbo Ke
- The Department of Physiology and Biophysics and Center for Cardiovascular Research, University of Illinois at Chicago, College of Medicine, Room 202, COMRB, 835 South Wolcott Avenue, Chicago, IL 60612, USA
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24
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Palpant NJ, D'Alecy LG, Metzger JM. Single histidine button in cardiac troponin I sustains heart performance in response to severe hypercapnic respiratory acidosis in vivo. FASEB J 2009; 23:1529-40. [PMID: 19141534 DOI: 10.1096/fj.08-121996] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Intracellular acidosis is a profound negative regulator of myocardial performance. We hypothesized that titrating myofilament calcium sensitivity by a single histidine substituted cardiac troponin I (A164H) would protect the whole animal physiological response to acidosis in vivo. To experimentally induce severe hypercapnic acidosis, mice were exposed to a 40% CO(2) challenge. By echocardiography, it was found that systolic function and ventricular geometry were maintained in cTnI A164H transgenic (Tg) mice. By contrast, non-Tg (Ntg) littermates experienced rapid and marked cardiac decompensation during this same challenge. For detailed hemodymanic assessment, Millar pressure-conductance catheterization was performed while animals were treated with a beta-blocker, esmolol, during a severe hypercapnic acidosis challenge. Survival and load-independent measures of contractility were significantly greater in Tg vs. Ntg mice. This assay showed that Ntg mice had 100% mortality within 5 min of acidosis. By contrast, systolic and diastolic function were protected in Tg mice during acidosis, and they had 100% survival. This study shows that, independent of any beta-adrenergic compensation, myofilament-based molecular manipulation of inotropy by histidine-modified troponin I maintains cardiac inotropic and lusitropic performance and markedly improves survival during severe acidosis in vivo.
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Affiliation(s)
- Nathan J Palpant
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, Michigan, USA
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25
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Yuan C, Sheng Q, Tang H, Li Y, Zeng R, Solaro RJ. Quantitative comparison of sarcomeric phosphoproteomes of neonatal and adult rat hearts. Am J Physiol Heart Circ Physiol 2008; 295:H647-56. [PMID: 18552161 DOI: 10.1152/ajpheart.00357.2008] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Neonatal hearts respond to stress and function in an environment quite different from adult hearts. There is evidence that these functional differences not only reflect modifications in the abundance and isoforms of sarcomeric proteins but also in the modulation of sarcomeric protein phosphorylation. Yet our understanding of changes in sarcomeric protein phosphorylation in development is incomplete. In the experiments reported here, we first quantified the intact sarcomeric protein phosphorylation status between neonatal and adult rat hearts by employing comparative two-dimensional (2-D) gel electrophoresis in conjunction with phosphoprotein-specific staining. Subsequently, we measured phosphorylation changes at the peptide level by employing high-resolution linear ion trap-Fourier transform (LTQ-FT) mass spectrometry analysis of titanium dioxide-enriched phosphopeptides differentially labeled with (16)O/(18)O during in-gel digestion. We also employed Western blot analysis using phosphorylation site-specific antibodies to measure phosphorylation changes. Our data demonstrated the novel finding that phosphorylation levels of myosin-binding protein C (MyBP-C) at Ser(295) and Ser(315) as well as tropomyosin at Ser(283) increased, whereas phosphorylation levels of MyBP-C at Ser(320) and myosin light chain 2 at Ser(15) decreased in neonatal hearts compared with the same sites in adult hearts. Although our data highlight the significant challenges in understanding relations between protein phosphorylation and cardiac function, they do support the hypothesis that developmental changes in the modulation of protein are functionally significant and correlate with the prevailing physiological state.
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Affiliation(s)
- Chao Yuan
- Department of Physiology and Biophysics, UIC, Chicago, IL 60612, USA
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Lu XY, Chen L, Cai XL, Yang HT. Overexpression of heat shock protein 27 protects against ischaemia/reperfusion-induced cardiac dysfunction via stabilization of troponin I and T. Cardiovasc Res 2008; 79:500-8. [DOI: 10.1093/cvr/cvn091] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
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Solaro RJ, Rosevear P, Kobayashi T. The unique functions of cardiac troponin I in the control of cardiac muscle contraction and relaxation. Biochem Biophys Res Commun 2007; 369:82-7. [PMID: 18162178 DOI: 10.1016/j.bbrc.2007.12.114] [Citation(s) in RCA: 98] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2007] [Accepted: 12/11/2007] [Indexed: 01/02/2023]
Abstract
We review development of evidence and current perceptions of the multiple and significant functions of cardiac troponin I in regulation and modulation of cardiac function. Our emphasis is on the unique structure function relations of the cardiac isoform of troponin I, especially regions containing sites of phosphorylation. The data indicate that modifications of specific regions cardiac troponin I by phosphorylations either promote or reduce cardiac contractility. Thus, a homeostatic balance in these phosphorylations is an important aspect of control of cardiac function. A new concept is the idea that the homeostatic mechanisms may involve modifications of intra-molecular interactions in cardiac troponin I.
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Affiliation(s)
- R John Solaro
- Department of Physiology and Biophysics (M/C901) and Center for Cardiovascular Research, 835 South Wolcott Avenue, University of Illinois at Chicago, College of Medicine, Chicago, IL 60612, USA
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Solaro RJ, Arteaga GM. Heart failure, ischemia/reperfusion injury and cardiac troponin. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2007; 592:191-200. [PMID: 17278366 DOI: 10.1007/978-4-431-38453-3_17] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Over the forty years since its discovery, there has been a profound transition in thinking with regard to the role of troponin in the control of cardiac function. This transition involved a change in perception oftroponin as a passive molecular switch responding to membrane controlled fluctuations in cytoplasmic Ca2+ to a perception of troponin as a critical element in signaling cascades that actively engage in control of cardiac function. Evidence demonstrating functionally significant developmental and mutant isoform switches and post-translational modifications of cardiac troponin complex proteins, troponin I (cTnI) and troponin T (cTnT) provided convincing evidence for a more complicated role of troponin in control of cardiac function and dynamics. The physiological role of these modifications of troponin is reviewed in this monograph and has also been reviewed elsewhere (Solaro and Rarick, 1998; Gordon et al., 2000; Solaro et al., 2002a; Kobayashi and Solaro, 2005). Our focus here is on studies related to modifications in troponin that appear important in the processes leading from compensated hypertrophy to heart failure. These studies reveal the potentially significant role of post-translational modifications of troponin in these processes. Another focus is on troponin as a target for inotropic agents. Pharmacological manipulation of troponin by small molecules remains an important avenue of approach for the treatment of acute and chronic heart failure (Kass and Solaro, 2006).
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Affiliation(s)
- R John Solaro
- Department of Physiology and Biophysics (M/C 901), University of Illinois at Chicago, College of Medicine, Chicago, IL 60612, USA
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Davis JP, Norman C, Kobayashi T, Solaro RJ, Swartz DR, Tikunova SB. Effects of thin and thick filament proteins on calcium binding and exchange with cardiac troponin C. Biophys J 2007; 92:3195-206. [PMID: 17293397 PMCID: PMC1852344 DOI: 10.1529/biophysj.106.095406] [Citation(s) in RCA: 98] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Understanding the effects of thin and thick filament proteins on the kinetics of Ca(2+) exchange with cardiac troponin C is essential to elucidating the Ca(2+)-dependent mechanisms controlling cardiac muscle contraction and relaxation. Unlike labeling of the endogenous Cys-84, labeling of cardiac troponin C at a novel engineered Cys-53 with 2-(4'-iodoacetamidoanilo)napthalene-6-sulfonic acid allowed us to accurately measure the rate of calcium dissociation from the regulatory domain of troponin C upon incorporation into the troponin complex. Neither tropomyosin nor actin alone affected the Ca(2+) binding properties of the troponin complex. However, addition of actin-tropomyosin to the troponin complex decreased the Ca(2+) sensitivity ( approximately 7.4-fold) and accelerated the rate of Ca(2+) dissociation from the regulatory domain of troponin C ( approximately 2.5-fold). Subsequent addition of myosin S1 to the reconstituted thin filaments (actin-tropomyosin-troponin) increased the Ca(2+) sensitivity ( approximately 6.2-fold) and decreased the rate of Ca(2+) dissociation from the regulatory domain of troponin C ( approximately 8.1-fold), which was completely reversed by ATP. Consistent with physiological data, replacement of cardiac troponin I with slow skeletal troponin I led to higher Ca(2+) sensitivities and slower Ca(2+) dissociation rates from troponin C in all the systems studied. Thus, both thin and thick filament proteins influence the ability of cardiac troponin C to sense and respond to Ca(2+). These results imply that both cross-bridge kinetics and Ca(2+) dissociation from troponin C work together to modulate the rate of cardiac muscle relaxation.
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Affiliation(s)
- Jonathan P Davis
- Department of Physiology and Cell Biology, The Ohio State University, Columbus, Ohio 43210, USA.
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Bupha-Intr T, Wattanapermpool J, Peña JR, Wolska BM, Solaro RJ. Myofilament response to Ca2+ and Na+/H+ exchanger activity in sex hormone-related protection of cardiac myocytes from deactivation in hypercapnic acidosis. Am J Physiol Regul Integr Comp Physiol 2007; 292:R837-43. [PMID: 17038443 DOI: 10.1152/ajpregu.00376.2006] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Compared to sham-operated controls, myofilaments from hearts of ovariectomized (OVX) rats demonstrate an increase in Ca2+ sensitivity with no change in maximum tension (Wattanapermpool J and Reiser PJ. Am J Physiol 277: H467–H473, 1999). To test the significance of this modification in intact cells, we compared intracellular Ca2+ transients and shortening of ventricular myocytes isolated from sham and 10-wk OVX rats. There was a decrease in the peak Ca2+ transient with prolonged 50% decay time in OVX cardiac myocytes without changes in the resting intracellular Ca2+ concentration. Percent cell shortening was also depressed, and relaxation was prolonged in cardiac myocytes from OVX rats compared with shams. Ovariectomy induced a sensitization of the myofilaments to Ca2+. Hypercapnic acidosis suppressed the shortening of OVX myocytes to a lesser extent than that detected in shams. Moreover, a larger compensatory increase in %cell shortening was obtained in OVX myocytes during prolonged acidosis. The elevated compensation in cell shortening was related to a higher amount of increase in the amplitude of the Ca2+ transient in OVX myocytes. However, these differences in Ca2+ transients and %cell shortening were no longer evident in the presence of 1 μM cariporide, a specific inhibitor of Na+/H+ exchanger type 1 (NHE1). Our results indicate that deprivation of female sex hormones modulates the intracellular Ca2+ concentration in cardiac myocytes, possibly via an increased NHE1 activity, which may act in concert with Ca2+ hypersensitivity of myofilament activation as a determinant of sex differences in cardiac function.
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Affiliation(s)
- Tepmanas Bupha-Intr
- Department of Physiology and Biophysics, Medicine and Center for Cardiovascular Research, College of Medicine, University of Illinois at Chicago, 835 S. Wolcott Ave., Chicago, IL 60612-7342, USA
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Affiliation(s)
- David A Kass
- Division of Cardiology, Department of Medicine, The Johns Hopkins University Medical Institutions, Baltimore, MD 21205, USA.
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