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Paratz ED, Mundisugih J, Rowe SJ, Kizana E, Semsarian C. Gene Therapy in Cardiology: Is a Cure for Hypertrophic Cardiomyopathy on the Horizon? Can J Cardiol 2024; 40:777-788. [PMID: 38013066 DOI: 10.1016/j.cjca.2023.11.024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Revised: 11/07/2023] [Accepted: 11/22/2023] [Indexed: 11/29/2023] Open
Abstract
Hypertrophic cardiomyopathy (HCM) is the most common genetic cardiomyopathy worldwide, affecting approximately 1 in 500 individuals. Current therapeutic interventions include lifestyle optimisation, medications, septal reduction therapies, and, rarely, cardiac transplantation. Advances in our understanding of disease-causing genetic variants in HCM and their associated molecular mechanisms have led to the potential for targeted therapeutics and implementation of precision and personalised medicine. Results from preclinical research are promising and raise the question of whether cure of some subtypes of HCM may be possible in the future. This review provides an overview of current genetic therapy platforms, including 1) genome editing, 2) gene replacement, 3) allelic-specific silencing, and 4) signalling pathway modulation. The current applicability of each of these platforms within the paradigm of HCM is examined, with updates on current and emerging trials in each domain. Barriers and limitations within the current landscape are also highlighted. Despite recent advances, translation of genetic therapy for HCM to clinical practice is still in early development. In realising the promises of genetic HCM therapies, ethical and equitable access to safe gene therapy must be prioritised.
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Affiliation(s)
- Elizabeth D Paratz
- Baker Heart and Diabetes Institute, Prahran, Victoria, Australia; St Vincent's Institute of Medical Research, Fitzroy, Victoria, Australia; Faculty of Medicine, Dentistry and Health Sciences, Melbourne University, Parkville, Victoria, Australia.
| | - Juan Mundisugih
- Centre for Heart Research, Westmead Institute for Medical Research, Westmead Clinical School, University of Sydney, Westmead, New South Wales, Australia; Department of Cardiology, Westmead Hospital, Westmead, New South Wales, Australia
| | - Stephanie J Rowe
- Baker Heart and Diabetes Institute, Prahran, Victoria, Australia; St Vincent's Institute of Medical Research, Fitzroy, Victoria, Australia; Faculty of Medicine, Dentistry and Health Sciences, Melbourne University, Parkville, Victoria, Australia
| | - Eddy Kizana
- Centre for Heart Research, Westmead Institute for Medical Research, Westmead Clinical School, University of Sydney, Westmead, New South Wales, Australia
| | - Christopher Semsarian
- Department of Cardiology, Royal Prince Alfred Hospital, Camperdown, New South Wales, Australia; Agnes Ginges Centre for Molecular Cardiology, Centenary Institute, University of Sydney, Camperdown, New South Wales, Australia
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Langa P, Marszalek RJ, Warren CM, Chowdhury SK, Halas M, Batra A, Rafael-Clyke K, Bacon A, Goldspink PH, Solaro RJ, Wolska BM. Altered coronary artery function, arteriogenesis and endothelial YAP signaling in postnatal hypertrophic cardiomyopathy. Front Physiol 2023; 14:1136852. [PMID: 37064918 PMCID: PMC10102353 DOI: 10.3389/fphys.2023.1136852] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Accepted: 03/13/2023] [Indexed: 04/03/2023] Open
Abstract
Introduction: Hypertrophic cardiomyopathy (HCM) is a cardiovascular genetic disease caused largely by sarcomere protein mutations. Gaps in our understanding exist as to how maladaptive sarcomeric biophysical signals are transduced to intra- and extracellular compartments leading to HCM progression. To investigate early HCM progression, we focused on the onset of myofilament dysfunction during neonatal development and examined cardiac dynamics, coronary vascular structure and function, and mechano-transduction signaling in mice harboring a thin-filament HCM mutation. Methods: We studied postnatal days 7-28 (P7-P28) in transgenic (TG) TG-cTnT-R92Q and non-transgenic (NTG) mice using skinned fiber mechanics, echocardiography, biochemistry, histology, and immunohistochemistry. Results: At P7, skinned myofiber bundles exhibited an increased Ca2+-sensitivity (pCa50 TG: 5.97 ± 0.04, NTG: 5.84 ± 0.01) resulting from cTnT-R92Q expression on a background of slow skeletal (fetal) troponin I and α/β myosin heavy chain isoform expression. Despite the transition to adult isoform expressions between P7-P14, the increased Ca2+- sensitivity persisted through P28 with no apparent differences in gross morphology among TG and NTG hearts. At P7 significant diastolic dysfunction was accompanied by coronary flow perturbation (mean diastolic velocity, TG: 222.5 ± 18.81 mm/s, NTG: 338.7 ± 28.07 mm/s) along with localized fibrosis (TG: 4.36% ± 0.44%, NTG: 2.53% ± 0.47%). Increased phosphorylation of phospholamban (PLN) was also evident indicating abnormalities in Ca2+ homeostasis. By P14 there was a decline in arteriolar cross-sectional area along with an expansion of fibrosis (TG: 9.72% ± 0.73%, NTG: 2.72% ± 0.2%). In comparing mechano-transduction signaling in the coronary arteries, we uncovered an increase in endothelial YAP expression with a decrease in its nuclear to cytosolic ratio at P14 in TG hearts, which was reversed by P28. Conclusion: We conclude that those early mechanisms that presage hypertrophic remodeling in HCM include defective biophysical signals within the sarcomere that drive diastolic dysfunction, impacting coronary flow dynamics, defective arteriogenesis and fibrosis. Changes in mechano-transduction signaling between the different cellular compartments contribute to the pathogenesis of HCM.
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Affiliation(s)
- Paulina Langa
- Department of Physiology and Biophysics, College of Medicine, University of Illinois at Chicago, Chicago, IL, United States
- Center for Cardiovascular Research, College of Medicine, University of Illinois at Chicago, Chicago, IL, United States
| | - Richard J. Marszalek
- Department of Physiology and Biophysics, College of Medicine, University of Illinois at Chicago, Chicago, IL, United States
- Center for Cardiovascular Research, College of Medicine, University of Illinois at Chicago, Chicago, IL, United States
| | - Chad M. Warren
- Department of Physiology and Biophysics, College of Medicine, University of Illinois at Chicago, Chicago, IL, United States
- Center for Cardiovascular Research, College of Medicine, University of Illinois at Chicago, Chicago, IL, United States
| | - Shamim K. Chowdhury
- Department of Physiology and Biophysics, College of Medicine, University of Illinois at Chicago, Chicago, IL, United States
| | - Monika Halas
- Department of Physiology and Biophysics, College of Medicine, University of Illinois at Chicago, Chicago, IL, United States
| | - Ashley Batra
- Department of Physiology and Biophysics, College of Medicine, University of Illinois at Chicago, Chicago, IL, United States
| | - Koreena Rafael-Clyke
- Department of Physiology and Biophysics, College of Medicine, University of Illinois at Chicago, Chicago, IL, United States
| | - Angelie Bacon
- Department of Physiology and Biophysics, College of Medicine, University of Illinois at Chicago, Chicago, IL, United States
| | - Paul H. Goldspink
- Department of Physiology and Biophysics, College of Medicine, University of Illinois at Chicago, Chicago, IL, United States
- Center for Cardiovascular Research, College of Medicine, University of Illinois at Chicago, Chicago, IL, United States
| | - R. John Solaro
- Department of Physiology and Biophysics, College of Medicine, University of Illinois at Chicago, Chicago, IL, United States
- Center for Cardiovascular Research, College of Medicine, University of Illinois at Chicago, Chicago, IL, United States
| | - Beata M. Wolska
- Department of Physiology and Biophysics, College of Medicine, University of Illinois at Chicago, Chicago, IL, United States
- Center for Cardiovascular Research, College of Medicine, University of Illinois at Chicago, Chicago, IL, United States
- Department of Medicine, Division of Cardiology, College of Medicine, University of Illinois at Chicago, Chicago, IL, United States
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Keyt LK, Duran JM, Bui QM, Chen C, Miyamoto MI, Silva Enciso J, Tardiff JC, Adler ED. Thin filament cardiomyopathies: A review of genetics, disease mechanisms, and emerging therapeutics. Front Cardiovasc Med 2022; 9:972301. [PMID: 36158814 PMCID: PMC9489950 DOI: 10.3389/fcvm.2022.972301] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2022] [Accepted: 07/28/2022] [Indexed: 11/17/2022] Open
Abstract
All muscle contraction occurs due to the cyclical interaction between sarcomeric thin and thick filament proteins within the myocyte. The thin filament consists of the proteins actin, tropomyosin, Troponin C, Troponin I, and Troponin T. Mutations in these proteins can result in various forms of cardiomyopathy, including hypertrophic, restrictive, and dilated phenotypes and account for as many as 30% of all cases of inherited cardiomyopathy. There is significant evidence that thin filament mutations contribute to dysregulation of Ca2+ within the sarcomere and may have a distinct pathomechanism of disease from cardiomyopathy associated with thick filament mutations. A number of distinct clinical findings appear to be correlated with thin-filament mutations: greater degrees of restrictive cardiomyopathy and relatively less left ventricular (LV) hypertrophy and LV outflow tract obstruction than that seen with thick filament mutations, increased morbidity associated with heart failure, increased arrhythmia burden and potentially higher mortality. Most therapies that improve outcomes in heart failure blunt the neurohormonal pathways involved in cardiac remodeling, while most therapies for hypertrophic cardiomyopathy involve use of negative inotropes to reduce LV hypertrophy or septal reduction therapies to reduce LV outflow tract obstruction. None of these therapies directly address the underlying sarcomeric dysfunction associated with thin-filament mutations. With mounting evidence that thin filament cardiomyopathies occur through a distinct mechanism, there is need for therapies targeting the unique, underlying mechanisms tailored for each patient depending on a given mutation.
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Affiliation(s)
- Lucas K. Keyt
- Department of Internal Medicine, University of California, San Diego, San Diego, CA, United States
| | - Jason M. Duran
- Department of Cardiology, University of California, San Diego, San Diego, CA, United States
| | - Quan M. Bui
- Department of Cardiology, University of California, San Diego, San Diego, CA, United States
| | - Chao Chen
- Department of Cardiology, University of California, San Diego, San Diego, CA, United States
| | | | - Jorge Silva Enciso
- Department of Cardiology, University of California, San Diego, San Diego, CA, United States
| | - Jil C. Tardiff
- Department of Medicine and Biomedical Engineering, University of Arizona, Tucson, AZ, United States
| | - Eric D. Adler
- Department of Cardiology, University of California, San Diego, San Diego, CA, United States
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Tamargo J, Tamargo M, Caballero R. Hypertrophic cardiomyopathy: an up-to-date snapshot of the clinical drug development pipeline. Expert Opin Investig Drugs 2022; 31:1027-1052. [PMID: 36062808 DOI: 10.1080/13543784.2022.2113374] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
INTRODUCTION Hypertrophic cardiomyopathy (HCM) is a complex cardiac disease with highly variable phenotypic expression and clinical course most often caused by sarcomeric gene mutations resulting in left ventricular hypertrophy, fibrosis, hypercontractility, and diastolic dysfunction. For almost 60 years, HCM has remained an orphan disease and still lacks a disease-specific treatment. AREAS COVERED This review summarizes recent preclinical and clinical trials with repurposed drugs and new emerging pharmacological and gene-based therapies for the treatment of HCM. EXPERT OPINION The off-label drugs routinely used alleviate symptoms but do not target the core pathophysiology of HCM or prevent or revert the phenotype. Recent advances in the genetics and pathophysiology of HCM led to the development of cardiac myosin adenosine triphosphatase inhibitors specifically directed to counteract the hypercontractility associated with HCM-causing mutations. Mavacamten, the first drug specifically developed for HCM successfully tested in a phase 3 trial, represents the major advance for the treatment of HCM. This opens new horizons for the development of novel drugs targeting HCM molecular substrates which hopefully modify the natural history of the disease. The role of current drugs in development and genetic-based approaches for the treatment of HCM are also discussed.
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Affiliation(s)
- Juan Tamargo
- Department of Pharmacology and Toxicology, School of Medicine, Universidad Complutense, Instituto de Investigación Sanitaria Gregorio Marañón, CIBERCV, 28040 Madrid, Spain
| | - María Tamargo
- Department of Cardiology, Hospital Universitario Gregorio Marañón, Instituto de Investigación Sanitaria Gregorio Marañón, CIBERCV, Doctor Esquerdo, 46, 28007 Madrid, Spain
| | - Ricardo Caballero
- Department of Pharmacology and Toxicology, School of Medicine, Universidad Complutense, Instituto de Investigación Sanitaria Gregorio Marañón, CIBERCV, 28040 Madrid, Spain
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Hulsurkar MM, Lahiri SK, Karch J, Wang MC, Wehrens XH. Targeting calcium-mediated inter-organellar crosstalk in cardiac diseases. Expert Opin Ther Targets 2022; 26:303-317. [PMID: 35426759 PMCID: PMC9081256 DOI: 10.1080/14728222.2022.2067479] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
INTRODUCTION Abnormal calcium signaling between organelles such as the sarcoplasmic reticulum (SR), mitochondria and lysosomes is a key feature of heart diseases. Calcium serves as a secondary messenger mediating inter-organellar crosstalk, essential for maintaining the cardiomyocyte function. AREAS COVERED This article examines the available literature related to calcium channels and transporters involved in inter-organellar calcium signaling. The SR calcium-release channels ryanodine receptor type-2 (RyR2) and inositol 1,4,5-trisphosphate receptor (IP3R), and calcium-transporter SR/ER-ATPase 2a (SERCA2a) are illuminated. The roles of mitochondrial voltage-dependent anion channels (VDAC), the mitochondria Ca2+ uniporter complex (MCUC), and the lysosomal H+/Ca2+ exchanger, two pore channels (TPC), and transient receptor potential mucolipin (TRPML) are discussed. Furthermore, recent studies showing calcium-mediated crosstalk between the SR, mitochondria, and lysosomes as well as how this crosstalk is dysregulated in cardiac diseases are placed under the spotlight. EXPERT OPINION Enhanced SR calcium release via RyR2 and reduced SR reuptake via SERCA2a, increased VDAC and MCUC-mediated calcium uptake into mitochondria, and enhanced lysosomal calcium-release via lysosomal TPC and TRPML may all contribute to aberrant calcium homeostasis causing heart disease. While mechanisms of this crosstalk need to be studied further, interventions targeting these calcium channels or combinations thereof might represent a promising therapeutic strategy.
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Affiliation(s)
- Mohit M. Hulsurkar
- Cardiovascular Research Institute
- Department of Molecular Physiology & Biophysics
| | - Satadru K. Lahiri
- Cardiovascular Research Institute
- Department of Molecular Physiology & Biophysics
| | - Jason Karch
- Cardiovascular Research Institute
- Department of Molecular Physiology & Biophysics
| | - Meng C. Wang
- Cardiovascular Research Institute
- Huffington Center on Aging
- Department of Molecular and Human Genetics
- Howard Hughes Medical Institute
| | - Xander H.T. Wehrens
- Cardiovascular Research Institute
- Department of Molecular Physiology & Biophysics
- Dept. of Medicine (Cardiology)
- Dept. of Neuroscience
- Dept. of Pediatrics (Cardiology)
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The Oxidative Balance Orchestrates the Main Keystones of the Functional Activity of Cardiomyocytes. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2022; 2022:7714542. [PMID: 35047109 PMCID: PMC8763515 DOI: 10.1155/2022/7714542] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Revised: 11/03/2021] [Accepted: 12/15/2021] [Indexed: 12/11/2022]
Abstract
This review is aimed at providing an overview of the key hallmarks of cardiomyocytes in physiological and pathological conditions. The main feature of cardiac tissue is the force generation through contraction. This process requires a conspicuous energy demand and therefore an active metabolism. The cardiac tissue is rich of mitochondria, the powerhouses in cells. These organelles, producing ATP, are also the main sources of ROS whose altered handling can cause their accumulation and therefore triggers detrimental effects on mitochondria themselves and other cell components thus leading to apoptosis and cardiac diseases. This review highlights the metabolic aspects of cardiomyocytes and wanders through the main systems of these cells: (a) the unique structural organization (such as different protein complexes represented by contractile, regulatory, and structural proteins); (b) the homeostasis of intracellular Ca2+ that represents a crucial ion for cardiac functions and E-C coupling; and (c) the balance of Zn2+, an ion with a crucial impact on the cardiovascular system. Although each system seems to be independent and finely controlled, the contractile proteins, intracellular Ca2+ homeostasis, and intracellular Zn2+ signals are strongly linked to each other by the intracellular ROS management in a fascinating way to form a "functional tetrad" which ensures the proper functioning of the myocardium. Nevertheless, if ROS balance is not properly handled, one or more of these components could be altered resulting in deleterious effects leading to an unbalance of this "tetrad" and promoting cardiovascular diseases. In conclusion, this "functional tetrad" is proposed as a complex network that communicates continuously in the cardiomyocytes and can drive the switch from physiological to pathological conditions in the heart.
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7
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Sewanan LR, Jacoby DL. Novel Myosin-Based Therapies in Hypertrophic Cardiomyopathy. CURRENT TREATMENT OPTIONS IN CARDIOVASCULAR MEDICINE 2021. [DOI: 10.1007/s11936-021-00921-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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8
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Bezzerides VJ, Prondzynski M, Carrier L, Pu WT. Gene therapy for inherited arrhythmias. Cardiovasc Res 2020; 116:1635-1650. [PMID: 32321160 PMCID: PMC7341167 DOI: 10.1093/cvr/cvaa107] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Revised: 03/13/2020] [Accepted: 04/15/2020] [Indexed: 01/16/2023] Open
Abstract
Inherited arrhythmias are disorders caused by one or more genetic mutations that increase the risk of arrhythmia, which result in life-long risk of sudden death. These mutations either primarily perturb electrophysiological homeostasis (e.g. long QT syndrome and catecholaminergic polymorphic ventricular tachycardia), cause structural disease that is closely associated with severe arrhythmias (e.g. hypertrophic cardiomyopathy), or cause a high propensity for arrhythmia in combination with altered myocardial structure and function (e.g. arrhythmogenic cardiomyopathy). Currently available therapies offer incomplete protection from arrhythmia and fail to alter disease progression. Recent studies suggest that gene therapies may provide potent, molecularly targeted options for at least a subset of inherited arrhythmias. Here, we provide an overview of gene therapy strategies, and review recent studies on gene therapies for catecholaminergic polymorphic ventricular tachycardia and hypertrophic cardiomyopathy caused by MYBPC3 mutations.
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Affiliation(s)
- Vassilios J Bezzerides
- Department of Cardiology, Boston Children’s Hospital, 300 Longwood Ave, Boston, MA 02115, USA
| | - Maksymilian Prondzynski
- Department of Cardiology, Boston Children’s Hospital, 300 Longwood Ave, Boston, MA 02115, USA
| | - Lucie Carrier
- Institute of Experimental and Clinical Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
- DZHK (German Centre for Cardiovascular Research), partner site, Hamburg/Kiel/Lübeck, Hamburg, Germany
| | - William T Pu
- Department of Cardiology, Boston Children’s Hospital, 300 Longwood Ave, Boston, MA 02115, USA
- Harvard Stem Cell Institute, 7 Divinity Avenue, Cambridge, MA 02138, USA
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9
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Baruah J, Chaudhuri S, Mastej V, Axen C, Hitzman R, Ribeiro IMB, Wary KK. Low-Level Nanog Expression in the Regulation of Quiescent Endothelium. Arterioscler Thromb Vasc Biol 2020; 40:2244-2264. [PMID: 32640900 PMCID: PMC7447188 DOI: 10.1161/atvbaha.120.314875] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Supplemental Digital Content is available in the text. Nanog is expressed in adult endothelial cells (ECs) at a low-level, however, its functional significance is not known. The goal of our study was to elucidate the role of Nanog in adult ECs using a genetically engineered mouse model system.
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Affiliation(s)
- Jugajyoti Baruah
- From the Department of Psychiatry, Harvard Medical School, Boston, MA (J.B.).,Angiogenesis and Brain Development Laboratory, Division of Basic Neuroscience, McLean Hospital, Belmont, MA (J.B.)
| | - Suhnrita Chaudhuri
- Department of Pharmacology and Regenerative Medicine, University of Illinois, Chicago (V.M., S.C., C.A., R.H., I.M.B.R., K.K.W.)
| | - Victoria Mastej
- Department of Pharmacology and Regenerative Medicine, University of Illinois, Chicago (V.M., S.C., C.A., R.H., I.M.B.R., K.K.W.)
| | - Cassondra Axen
- Department of Pharmacology and Regenerative Medicine, University of Illinois, Chicago (V.M., S.C., C.A., R.H., I.M.B.R., K.K.W.)
| | - Ryan Hitzman
- Department of Pharmacology and Regenerative Medicine, University of Illinois, Chicago (V.M., S.C., C.A., R.H., I.M.B.R., K.K.W.)
| | - Isabella M B Ribeiro
- Department of Pharmacology and Regenerative Medicine, University of Illinois, Chicago (V.M., S.C., C.A., R.H., I.M.B.R., K.K.W.)
| | - Kishore K Wary
- Department of Pharmacology and Regenerative Medicine, University of Illinois, Chicago (V.M., S.C., C.A., R.H., I.M.B.R., K.K.W.)
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10
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Peixoto JVC, Santos ASR, Corso CR, da Silva FS, Capote A, Ribeiro CD, Abreu BJDGA, Acco A, Fogaça RH, Dias FAL. Thirty-day experimental diabetes impairs contractility and increases fatigue resistance in rat diaphragm muscle associated with increased anti-oxidative activity. Can J Physiol Pharmacol 2020; 98:490-497. [PMID: 32243773 DOI: 10.1139/cjpp-2019-0609] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Diabetes mellitus is a metabolic disorder that can generate tissue damage through several pathways. Alteration and dysfunction of skeletal muscle are reported including respiratory muscles, which may compromise respiratory parameters in diabetic patients. We have aimed to evaluate the diaphragm muscle contractility, tissue remodeling, oxidative stress, and inflammatory parameters from 30 day streptozotocin-treated rats. The diaphragm contractility was assessed using isolated muscle, tissue remodeling using histology and zymography techniques, and tissue oxidative stress and inflammatory parameters by enzyme activity assay. Our data revealed in the diabetes mellitus group an increase in maximum tetanic force (4.82 ± 0.13 versus 4.24 ± 0.18 N/cm2 (p = 0.015)) and fatigue resistance (139.16 ± 10.78 versus 62.25 ± 4.45 s (p < 0.001)), reduction of 35.4% in muscle trophism (p < 0.001), increase of 32.6% of collagen deposition (p = 0.007), reduction of 21.3% in N-acetylglucosaminidase activity (p < 0.001), and increase of 246.7% of catalase activity (p = 0.002) without changes in reactive oxygen species (p = 0.518) and tissue lipid peroxidation (p = 0.664). All observed changes are attributed to the poor glycemic control (471.20 ± 16.91 versus 80.00 ± 3.42 mg/dL (p < 0.001)), which caused defective tissue regeneration and increased catalase activity as a compensatory mechanism.
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Affiliation(s)
- João Victor Capelli Peixoto
- Department of Physiology, Federal University of Paraná, Av. Francisco H. dos Santos 100, Jardim das Américas, Curitiba, Paraná 81531-980, Brazil
| | - Antônio Sérgio Rocha Santos
- Department of Physiology, Federal University of Paraná, Av. Francisco H. dos Santos 100, Jardim das Américas, Curitiba, Paraná 81531-980, Brazil
| | - Claudia Rita Corso
- Department of Pharmacology, Federal University of Paraná, Av. Francisco H. dos Santos 100, Jardim das Américas, Curitiba, Paraná 81531-980, Brazil
| | - Flavio Santos da Silva
- Department of Health Sciences, Federal Rural University of the Semi-Arid, Av. Francisco Mota 572, Pres. Costa e Silva, Mossoró, Rio Grande do Norte 59625-900, Brazil
| | - Andrielle Capote
- Department of Physiology, Federal University of Paraná, Av. Francisco H. dos Santos 100, Jardim das Américas, Curitiba, Paraná 81531-980, Brazil
| | - Cibele Dias Ribeiro
- Department of Physiology, Federal University of Paraná, Av. Francisco H. dos Santos 100, Jardim das Américas, Curitiba, Paraná 81531-980, Brazil
| | - Bento João da Graça Azevedo Abreu
- Department of Morphology, Federal University of Rio Grande do Norte, Av. Senador Salgado Filho 3000, Candelária, Natal, Rio Grande do Norte 59064-741, Brazil
| | - Alexandra Acco
- Department of Pharmacology, Federal University of Paraná, Av. Francisco H. dos Santos 100, Jardim das Américas, Curitiba, Paraná 81531-980, Brazil
| | - Rosalvo Hochmueller Fogaça
- Department of Physiology, Federal University of Paraná, Av. Francisco H. dos Santos 100, Jardim das Américas, Curitiba, Paraná 81531-980, Brazil
| | - Fernando Augusto Lavezzo Dias
- Department of Physiology, Federal University of Paraná, Av. Francisco H. dos Santos 100, Jardim das Américas, Curitiba, Paraná 81531-980, Brazil
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11
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Chowdhury SAK, Warren CM, Simon JN, Ryba DM, Batra A, Varga P, Kranias EG, Tardiff JC, Solaro RJ, Wolska BM. Modifications of Sarcoplasmic Reticulum Function Prevent Progression of Sarcomere-Linked Hypertrophic Cardiomyopathy Despite a Persistent Increase in Myofilament Calcium Response. Front Physiol 2020; 11:107. [PMID: 32210830 PMCID: PMC7075858 DOI: 10.3389/fphys.2020.00107] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Accepted: 01/30/2020] [Indexed: 01/12/2023] Open
Abstract
Hypertrophic cardiomyopathy (HCM) is a genetic disorder caused by mutations in different genes mainly encoding myofilament proteins and therefore called a “disease of the sarcomere.” Despite the discovery of sarcomere protein mutations linked to HCM almost 30 years ago, the cellular mechanisms responsible for the development of this disease are not completely understood and likely vary among different mutations. Moreover, despite many efforts to develop effective treatments for HCM, these have largely been unsuccessful, and more studies are needed to better understand the cellular mechanisms of the disease. In experiments reported here, we investigated a mouse model expressing the mutant cTnT-R92Q, which is linked to HCM and induces an increase in myofilament Ca2+ sensitivity and diastolic dysfunction. We found that early correction of the diastolic dysfunction by phospholamban knockout (PLNKO) was able to prevent the development of the HCM phenotype in troponin T (TnT)-R92Q transgenic (TG) mice. Four groups of mice in FVB/N background were generated and used for the experiments: (1) non-transgenic (NTG)/PLN mice, which express wild-type TnT and normal level of PLN; (2) NTG/PLNKO mice, which express wild-type TnT and no PLN; (3) TG/PLN mice, which express TnT-R92Q and normal level of PLN; (4) TG/PLNKO mice, which express TnT-R92Q and no PLN. Cardiac function was determined using both standard echocardiographic parameters and speckle tracking strain measurements. We found that both atrial morphology and diastolic function were altered in TG/PLN mice but normal in TG/PLNKO mice. Histological analysis showed a disarray of myocytes and increased collagen deposition only in TG/PLN hearts. We also observed increased Ca2+/calmodulin-dependent protein kinase II (CaMKII) phosphorylation only in TG/PLN hearts but not in TG/PLNKO hearts. The rescue of the HCM phenotype was not associated with differences in myofilament Ca2+ sensitivity between TG/PLN and TG/PLNKO mice. Moreover, compared to standard systolic echo parameters, such as ejection fraction (EF), speckle strain measurements provided a more sensitive approach to detect early systolic dysfunction in TG/PLN mice. In summary, our results indicate that targeting diastolic dysfunction through altering Ca2+ fluxes with no change in myofilament response to Ca2+ was able to prevent the development of the HCM phenotype and should be considered as a potential additional treatment for HCM patients.
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Affiliation(s)
- Shamim A K Chowdhury
- Department of Physiology and Biophysics and the Center for Cardiovascular Research, College of Medicine, University of Illinois at Chicago, Chicago, IL, United States
| | - Chad M Warren
- Department of Physiology and Biophysics and the Center for Cardiovascular Research, College of Medicine, University of Illinois at Chicago, Chicago, IL, United States
| | - Jillian N Simon
- Department of Physiology and Biophysics and the Center for Cardiovascular Research, College of Medicine, University of Illinois at Chicago, Chicago, IL, United States
| | - David M Ryba
- Department of Physiology and Biophysics and the Center for Cardiovascular Research, College of Medicine, University of Illinois at Chicago, Chicago, IL, United States
| | - Ashley Batra
- Department of Physiology and Biophysics and the Center for Cardiovascular Research, College of Medicine, University of Illinois at Chicago, Chicago, IL, United States
| | - Peter Varga
- Department of Pediatrics, Section of Cardiology, University of Illinois at Chicago, Chicago, IL, United States
| | - Evangelia G Kranias
- Department of Pharmacology and Systems Physiology, University of Cincinnati, Cincinnati, OH, United States
| | - Jil C Tardiff
- Department of Medicine, Division of Cardiology, The University of Arizona, Tucson, AZ, United States
| | - R John Solaro
- Department of Physiology and Biophysics and the Center for Cardiovascular Research, College of Medicine, University of Illinois at Chicago, Chicago, IL, United States
| | - Beata M Wolska
- Department of Physiology and Biophysics and the Center for Cardiovascular Research, College of Medicine, University of Illinois at Chicago, Chicago, IL, United States.,Department of Medicine, Division of Cardiology, University of Illinois at Chicago, Chicago, IL, United States
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12
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Abstract
Heritable cardiomyopathies are a class of heart diseases caused by variations in a number of genetic loci. Genetic variants on one allele lead to either a degraded protein, which causes a haploinsufficiency of that protein, or a nonfunctioning protein that subverts the molecular system within which the protein works. Over years, both of these mechanisms eventually lead to diseased heart tissue and symptoms of a failing heart. Most cardiomyopathy treatments repurpose heart failure drugs to manage these symptoms and avoid adverse outcomes. There are few therapies that correct the underlying pathogenic genetic or molecular mechanism. This review will reflect on this unmet clinical need in genetic cardiomyopathies and consider a variety of therapies that address the mechanism of disease rather than patient symptoms. These therapies are genetic, targeting a defective gene or transcript, or ameliorating a genetic insufficiency. However, there are also a number of small molecules under exploration that modulate downstream faulty protein products affected in cardiomyopathies.
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Affiliation(s)
- Giuliana G Repetti
- From the Department of Genetics, Harvard Medical School, Boston, MA (G.G.R., C.N.T., J.G.S., C.E.S.)
| | - Christopher N Toepfer
- From the Department of Genetics, Harvard Medical School, Boston, MA (G.G.R., C.N.T., J.G.S., C.E.S.)
- Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, United Kingdom (C.N.T.)
- Cardiovascular Division, Brigham and Women's Hospital, Boston, MA (C.N.T., C.E.S.)
| | - Jonathan G Seidman
- From the Department of Genetics, Harvard Medical School, Boston, MA (G.G.R., C.N.T., J.G.S., C.E.S.)
| | - Christine E Seidman
- From the Department of Genetics, Harvard Medical School, Boston, MA (G.G.R., C.N.T., J.G.S., C.E.S.)
- Howard Hughes Medical Institute, Chevy Chase, MD (C.E.S.)
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13
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Coronary arterial vasculature in the pathophysiology of hypertrophic cardiomyopathy. Pflugers Arch 2018; 471:769-780. [PMID: 30370501 DOI: 10.1007/s00424-018-2224-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Accepted: 10/16/2018] [Indexed: 02/07/2023]
Abstract
Alterations in the coronary vascular system are likely associated with a mismatch between energy demand and energy supply and critical in triggering the cascade of events that leads to symptomatic hypertrophic cardiomyopathy. Targeting the early events, particularly vascular remodeling, may be a key approach to developing effective treatments. Improvement in our understanding of hypertrophic cardiomyopathy began with the results of early biophysical studies, proceeded to genetic analyses pinpointing the mutational origin, and now pertains to imaging of the metabolic and flow-related consequences of such mutations. Microvascular dysfunction has been an ongoing hot topic in the imaging of genetic cardiomyopathies marked by its histologically significant remodeling and has proven to be a powerful asset in determining prognosis for these patients as well as enlightening scientists on a potential pathophysiological cascade that may begin early during the developmental process. Here, we discuss questions that continue to remain on the mechanistic processes leading to microvascular dysfunction, its correlation to the morphological changes in the vessels, and its contribution to disease progression.
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14
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Alves ML, Warren CM, Simon JN, Gaffin RD, Montminy EM, Wieczorek DF, Solaro RJ, Wolska BM. Early sensitization of myofilaments to Ca2+ prevents genetically linked dilated cardiomyopathy in mice. Cardiovasc Res 2018; 113:915-925. [PMID: 28379313 DOI: 10.1093/cvr/cvx068] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Accepted: 03/31/2017] [Indexed: 12/14/2022] Open
Abstract
Background Dilated cardiomoypathies (DCM) are a heterogeneous group of inherited and acquired diseases characterized by decreased contractility and enlargement of cardiac chambers and a major cause of morbidity and mortality. Mice with Glu54Lys mutation in α-tropomyosin (Tm54) demonstrate typical DCM phenotype with reduced myofilament Ca2+ sensitivity. We tested the hypothesis that early sensitization of the myofilaments to Ca2+ in DCM can prevent the DCM phenotype. Methods and results To sensitize Tm54 myofilaments, we used a genetic approach and crossbred Tm54 mice with mice expressing slow skeletal troponin I (ssTnI) that sensitizes myofilaments to Ca2+. Four groups of mice were used: non-transgenic (NTG), Tm54, ssTnI and Tm54/ssTnI (DTG). Systolic function was significantly reduced in the Tm54 mice compared to NTG, but restored in DTG mice. Tm54 mice also showed increased diastolic LV dimensions and HW/BW ratios, when compared to NTG, which were improved in the DTG group. β-myosin heavy chain expression was increased in the Tm54 animals compared to NTG and was partially restored in DTG group. Analysis by 2D-DIGE indicated a significant decrease in two phosphorylated spots of cardiac troponin I (cTnI) in the DTG animals compared to NTG and Tm54. Analysis by 2D-DIGE also indicated no significant changes in troponin T, regulatory light chain, myosin binding protein C and tropomyosin phosphorylation. Conclusion Our data indicate that decreased myofilament Ca2+ sensitivity is an essential element in the pathophysiology of thin filament linked DCM. Sensitization of myofilaments to Ca2+ in the early stage of DCM may be a useful therapeutic strategy in thin filament linked DCM.
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Affiliation(s)
- Marco L Alves
- Department of Physiology and Biophysics, Center for Cardiovascular Research, University of Illinois, 835 S Wolcott Ave. (M/C 901), Chicago, IL 60612, USA.,Center for Research in Echocardiography and Cardiology, Heart Institute, University of Sao Paulo, Avenida Dr. Eneas de Carvalho Aguiar 44, 05403-900, Sao Paulo, Brazil
| | - Chad M Warren
- Department of Physiology and Biophysics, Center for Cardiovascular Research, University of Illinois, 835 S Wolcott Ave. (M/C 901), Chicago, IL 60612, USA
| | - Jillian N Simon
- Department of Physiology and Biophysics, Center for Cardiovascular Research, University of Illinois, 835 S Wolcott Ave. (M/C 901), Chicago, IL 60612, USA
| | - Robert D Gaffin
- Department of Physiology and Biophysics, Center for Cardiovascular Research, University of Illinois, 835 S Wolcott Ave. (M/C 901), Chicago, IL 60612, USA
| | - Eric M Montminy
- Department of Physiology and Biophysics, Center for Cardiovascular Research, University of Illinois, 835 S Wolcott Ave. (M/C 901), Chicago, IL 60612, USA
| | - David F Wieczorek
- Department of Molecular Genetics, Biochemistry and Microbiology, University of Cincinnati, College of Medicine, 231 Albert Sabin Way, Cincinnati, OH 45267, USA
| | - R John Solaro
- Department of Physiology and Biophysics, Center for Cardiovascular Research, University of Illinois, 835 S Wolcott Ave. (M/C 901), Chicago, IL 60612, USA
| | - Beata M Wolska
- Department of Physiology and Biophysics, Center for Cardiovascular Research, University of Illinois, 835 S Wolcott Ave. (M/C 901), Chicago, IL 60612, USA.,Department of Medicine, Division of Cardiology, University of Illinois, 840 S Wood St. (M/C 715), Chicago, IL 60612, USA
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15
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Abstract
PURPOSE OF REVIEW Cardiomyopathies due to genetic mutations are a heterogeneous group of disorders that comprise diseases of contractility, myocardial relaxation, and arrhythmias. Our goal here is to discuss a limited list of genetically inherited cardiomyopathies and the specific therapeutic strategies used to treat them. RECENT FINDINGS Research into the molecular pathophysiology of the development of these cardiomyopathies is leading to the development of novel treatment approaches. Therapies targeting these specific mutations with gene therapy vectors are on the horizon, while other therapies which indirectly affect the physiologic derangements of the mutations are currently being studied and used clinically. Many of these therapies are older medications being given new roles such as mexiletine for Brugada syndrome and diflunisal for transthyretin amyloid cardiomyopathy. A newer targeted therapy, the inhibitor of myosin ATPase MYK-461, has been shown to suppress the development of ventricular hypertrophy, fibrosis, and myocyte disarray and is being studied as a potential therapy in patients with hypertrophic cardiomyopathy. While this field is too large to be completely contained in a single review, we present a large cross section of recent developments in the field of therapeutics for inherited cardiomyopathies. New therapies are on the horizon, and their development will likely result in improved outcomes for patients inflicted by these conditions.
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Affiliation(s)
- Kenneth Varian
- Department of Cardiovascular Medicine, Heart and Vascular Institute, Cleveland Clinic, 9500 Euclid Avenue, Desk J3-4, Cleveland, OH, 44195, USA
| | - W H Wilson Tang
- Department of Cardiovascular Medicine, Heart and Vascular Institute, Cleveland Clinic, 9500 Euclid Avenue, Desk J3-4, Cleveland, OH, 44195, USA. .,Center for Clinical Genomics, Cleveland Clinic, Cleveland, OH, USA.
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16
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Baruah J, Hitzman R, Zhang J, Chaudhuri S, Mastej V, Wary KK. The allosteric glycogen synthase kinase-3 inhibitor NP12 limits myocardial remodeling and promotes angiogenesis in an acute myocardial infarction model. J Biol Chem 2017; 292:20785-20798. [PMID: 29070680 DOI: 10.1074/jbc.m117.814376] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Revised: 10/19/2017] [Indexed: 12/22/2022] Open
Abstract
A key feature of acute myocardial infarction (AMI) is an alteration in cardiac architecture. Signaling events that result in the inhibition of glycogen synthase kinase-3 (GSK-3)β represent an adaptive response that might limit the extent of adverse remodeling in the aftermath of AMI. Here, we report that an allosteric inhibitor of GSK-3β, 4-benzyl-2-(naphthalene-1-yl)-1,2,4-thiadiazolidine-3,5-dione (NP12), lessens the magnitude of adverse myocardial remodeling and promotes angiogenesis. Male and female mice 8-10 weeks old were grouped (six animals in each group) into sham surgery (sham group), left anterior descending (LAD) ligation of the coronary artery followed by intramyocardial PBS injections (control group), and LAD ligation followed by NP12 administration (NP12 group). After 7 and 14 days, the extents of fibrosis and integrity of blood vessels were determined. Intramyocardial administration of NP12 increased phosphorylation of GSK-3β, reduced fibrosis, and restored diastolic function in the mice that had experienced an AMI. Morphometric analyses revealed increased CD31+ and Ki67+ vascular structures and decreased apoptosis in these mice. NP12 administration mediated proliferation of reparative cells in the AMI hearts. In a time-course analysis, Wnt3a and NP12 stabilized β-catenin and increased expression of both Nanog and VEGFR2. Moreover, NP12 increased the expression of β-catenin and Nanog in myocardium from AMI mice. Finally, loss- and gain-of-function experiments indicated that the NP12-mediated benefit is, in part, Nanog-specific. These findings indicate that NP12 reduces fibrosis, reestablishes coronary blood flow, and improves ventricular function following an AMI. We conclude that NP12 might be useful for limiting ventricular remodeling after an AMI.
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Affiliation(s)
- Jugajyoti Baruah
- From the Department of Pharmacology, University of Illinois, Chicago, Illinois 60612
| | - Ryan Hitzman
- From the Department of Pharmacology, University of Illinois, Chicago, Illinois 60612
| | - Jane Zhang
- From the Department of Pharmacology, University of Illinois, Chicago, Illinois 60612
| | - Suhnrita Chaudhuri
- From the Department of Pharmacology, University of Illinois, Chicago, Illinois 60612
| | - Victoria Mastej
- From the Department of Pharmacology, University of Illinois, Chicago, Illinois 60612
| | - Kishore K Wary
- From the Department of Pharmacology, University of Illinois, Chicago, Illinois 60612
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17
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Sewanan LR, Moore JR, Lehman W, Campbell SG. Predicting Effects of Tropomyosin Mutations on Cardiac Muscle Contraction through Myofilament Modeling. Front Physiol 2016; 7:473. [PMID: 27833562 PMCID: PMC5081029 DOI: 10.3389/fphys.2016.00473] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2016] [Accepted: 10/03/2016] [Indexed: 12/23/2022] Open
Abstract
Point mutations to the human gene TPM1 have been implicated in the development of both hypertrophic and dilated cardiomyopathies. Such observations have led to studies investigating the link between single residue changes and the biophysical behavior of the tropomyosin molecule. However, the degree to which these molecular perturbations explain the performance of intact sarcomeres containing mutant tropomyosin remains uncertain. Here, we present a modeling approach that integrates various aspects of tropomyosin's molecular properties into a cohesive paradigm representing their impact on muscle function. In particular, we considered the effects of tropomyosin mutations on (1) persistence length, (2) equilibrium between thin filament blocked and closed regulatory states, and (3) the crossbridge duty cycle. After demonstrating the ability of the new model to capture Ca-dependent myofilament responses during both dynamic and steady-state activation, we used it to capture the effects of hypertrophic cardiomyopathy (HCM) related E180G and D175N mutations on skinned myofiber mechanics. Our analysis indicates that the fiber-level effects of the two mutations can be accurately described by a combination of changes to the three tropomyosin properties represented in the model. Subsequently, we used the model to predict mutation effects on muscle twitch. Both mutations led to increased twitch contractility as a consequence of diminished cooperative inhibition between thin filament regulatory units. Overall, simulations suggest that a common twitch phenotype for HCM-linked tropomyosin mutations includes both increased contractility and elevated diastolic tension.
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Affiliation(s)
- Lorenzo R Sewanan
- Department of Biomedical Engineering, Yale UniversityNew Haven, CT, USA; Yale School of Medicine, Yale UniversityNew Haven, CT, USA
| | - Jeffrey R Moore
- Department of Biological Sciences, University of Massachusetts Lowell Lowell, MA, USA
| | - William Lehman
- Department of Physiology and Biophysics, Boston University School of Medicine Boston, MA, USA
| | - Stuart G Campbell
- Department of Biomedical Engineering, Yale UniversityNew Haven, CT, USA; Department of Cellular and Molecular Physiology, Yale School of MedicineNew Haven, CT, USA
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18
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Martins AS, Parvatiyar MS, Feng HZ, Bos JM, Gonzalez-Martinez D, Vukmirovic M, Turna RS, Sanchez-Gonzalez MA, Badger CD, Zorio DAR, Singh RK, Wang Y, Jin JP, Ackerman MJ, Pinto JR. In Vivo Analysis of Troponin C Knock-In (A8V) Mice: Evidence that TNNC1 Is a Hypertrophic Cardiomyopathy Susceptibility Gene. ACTA ACUST UNITED AC 2015; 8:653-664. [PMID: 26304555 DOI: 10.1161/circgenetics.114.000957] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Accepted: 08/04/2015] [Indexed: 01/10/2023]
Abstract
BACKGROUND Mutations in thin-filament proteins have been linked to hypertrophic cardiomyopathy, but it has never been demonstrated that variants identified in the TNNC1 (gene encoding troponin C) can evoke cardiac remodeling in vivo. The goal of this study was to determine whether TNNC1 can be categorized as an hypertrophic cardiomyopathy susceptibility gene, such that a mouse model can recapitulate the clinical presentation of the proband. METHODS AND RESULTS The TNNC1-A8V proband diagnosed with severe obstructive hypertrophic cardiomyopathy at 34 years of age exhibited mild-to-moderate thickening in left and right ventricular walls, decreased left ventricular dimensions, left atrial enlargement, and hyperdynamic left ventricular systolic function. Genetically engineered knock-in (KI) mice containing the A8V mutation (heterozygote=KI-TnC-A8V(+/-); homozygote=KI-TnC-A8V(+/+)) were characterized by echocardiography and pressure-volume studies. Three-month-old KI-TnC-A8V(+/+) mice displayed decreased ventricular dimensions, mild diastolic dysfunction, and enhanced systolic function, whereas KI-TnC-A8V(+/-) mice displayed cardiac restriction at 14 months of age. KI hearts exhibited atrial enlargement, papillary muscle hypertrophy, and fibrosis. Liquid chromatography-mass spectroscopy was used to determine incorporation of mutant cardiac troponin C (≈ 21%) into the KI-TnC-A8V(+/-) cardiac myofilament. Reduced diastolic sarcomeric length, increased shortening, and prolonged Ca(2+) and contractile transients were recorded in intact KI-TnC-A8V(+/-) and KI-TnC-A8V(+/+) cardiomyocytes. Ca(2+) sensitivity of contraction in skinned fibers increased with mutant gene dose: KI-TnC-A8V(+/+)>KI-TnC-A8V(+/-)>wild-type, whereas KI-TnC-A8V(+/+) relaxed more slowly on flash photolysis of diazo-2. CONCLUSIONS The TNNC1-A8V mutant increases the Ca(2+)-binding affinity of the thin filament and elicits changes in Ca(2+) homeostasis and cellular remodeling, which leads to diastolic dysfunction. These in vivo alterations further implicate the role of TNNC1 mutations in the development of cardiomyopathy.
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Affiliation(s)
- Adriano S Martins
- Department of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee
| | - Michelle S Parvatiyar
- Department of Molecular and Cellular Pharmacology, University of Miami, Miller School of Medicine, Miami, FL
| | - Han-Zhong Feng
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI
| | - J Martijn Bos
- Department of Molecular Pharmacology & Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, MN
| | - David Gonzalez-Martinez
- Department of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee
| | - Milica Vukmirovic
- Department of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee
| | - Rajdeep S Turna
- Department of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee
| | - Marcos A Sanchez-Gonzalez
- Department of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee.,Department of Biomedical Sciences, Larkin Health Sciences Institute, South Miami, FL
| | - Crystal-Dawn Badger
- Department of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee
| | - Diego A R Zorio
- Department of Chemistry & Biochemistry, College of Medicine, Florida State University, Tallahassee
| | - Rakesh K Singh
- Translational Science Laboratory, College of Medicine, Florida State University, Tallahassee
| | - Yingcai Wang
- Department of Molecular and Cellular Pharmacology, University of Miami, Miller School of Medicine, Miami, FL
| | - J-P Jin
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI
| | - Michael J Ackerman
- Department of Molecular Pharmacology & Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, MN.,Department of Medicine/Division of Cardiovascular Diseases, Mayo Clinic, Rochester, MN.,Department of Pediatrics/Division of Pediatric Cardiology, Mayo Clinic, Rochester, MN
| | - Jose R Pinto
- Department of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee
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19
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Leviner DB, Hochhauser E, Arad M. Inherited cardiomyopathies--Novel therapies. Pharmacol Ther 2015; 155:36-48. [PMID: 26297672 DOI: 10.1016/j.pharmthera.2015.08.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/10/2015] [Indexed: 01/10/2023]
Abstract
Cardiomyopathies arising due to a single gene defect represent various pathways that evoke adverse remodeling and cardiac dysfunction. While the gene therapy approach is slowly evolving and has not yet reached clinical "prime time" and gene correction approaches are applicable at the bench but not at the bedside, major advances are being made with molecular and drug therapies. This review summarizes the contemporary drugs introduced or being tested to help manage these unique disorders bearing a major impact on the quality of life and survival of the affected individuals. The restoration of the RNA reading frame facilitates the expression of partly functional protein to salvage or alleviate the disease phenotype. Chaperones are used to prevent the degradation of abnormal but still functional proteins, while other molecules are given for pathogen silencing, to prevent aggregation or to enhance clearance of protein deposits. The absence of protein may be managed by viral gene delivery or protein therapy. Enzyme replacement therapy is already a clinical reality for a series of metabolic diseases. The progress in molecular biology, based on the knowledge of the gene defect, helps generate small molecules and pharmaceuticals targeting the key events occurring in the malfunctioning element of the sick organ. Cumulatively, these tools augment the existing armamentarium of phenotype oriented symptomatic and evidence-based therapies for patients with inherited cardiomyopathies.
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Affiliation(s)
- Dror B Leviner
- Department of Cardiothoracic Surgery, Rabin Medical Center, Petah Tikva, Israel; Cardiac Research Laboratory, Felsenstein Medical Research Center, Petah Tikva and Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Edith Hochhauser
- Cardiac Research Laboratory, Felsenstein Medical Research Center, Petah Tikva and Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Michael Arad
- Leviev Heart Center, Sheba Medical Center, Tel Hashomer and Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel.
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20
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SERCA2 Haploinsufficiency in a Mouse Model of Darier Disease Causes a Selective Predisposition to Heart Failure. BIOMED RESEARCH INTERNATIONAL 2015; 2015:251598. [PMID: 26064889 PMCID: PMC4433638 DOI: 10.1155/2015/251598] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/26/2014] [Revised: 12/18/2014] [Accepted: 12/23/2014] [Indexed: 12/28/2022]
Abstract
Null mutations in one copy of ATP2A2, the gene encoding sarco/endoplasmic reticulum Ca(2+)-ATPase isoform 2 (SERCA2), cause Darier disease in humans, a skin condition involving keratinocytes. Cardiac function appears to be unimpaired in Darier disease patients, with no evidence that SERCA2 haploinsufficiency itself causes heart disease. However, SERCA2 deficiency is widely considered a contributing factor in heart failure. We therefore analyzed Atp2a2 heterozygous mice to determine whether SERCA2 haploinsufficiency can exacerbate specific heart disease conditions. Despite reduced SERCA2a levels in heart, Atp2a2 heterozygous mice resembled humans in exhibiting normal cardiac physiology. When subjected to hypothyroidism or crossed with a transgenic model of reduced myofibrillar Ca(2+)-sensitivity, SERCA2 deficiency caused no enhancement of the disease state. However, when combined with a transgenic model of increased myofibrillar Ca(2+)-sensitivity, SERCA2 haploinsufficiency caused rapid onset of hypertrophy, decompensation, and death. These effects were associated with reduced expression of the antiapoptotic Hax1, increased levels of the proapoptotic genes Chop and Casp12, and evidence of perturbations in energy metabolism. These data reveal myofibrillar Ca(2+)-sensitivity to be an important determinant of the cardiac effects of SERCA2 haploinsufficiency and raise the possibility that Darier disease patients are more susceptible to heart failure under certain conditions.
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21
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Ablation of plasma membrane Ca(2+)-ATPase isoform 4 prevents development of hypertrophy in a model of hypertrophic cardiomyopathy. J Mol Cell Cardiol 2014; 77:53-63. [PMID: 25280781 DOI: 10.1016/j.yjmcc.2014.09.025] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Revised: 09/23/2014] [Accepted: 09/24/2014] [Indexed: 11/20/2022]
Abstract
The mechanisms linking the expression of sarcomeric mutant proteins to the development of pathological hypertrophy in hypertrophic cardiomyopathy (HCM) remain poorly understood. We investigated the role of the plasma membrane Ca(2+)-ATPase PMCA4 in the HCM phenotype using a transgenic model that expresses mutant (Glu180Gly) α-tropomyosin (Tm180) in heart. Immunoblot analysis revealed that cardiac PMCA4 expression was upregulated early in Tm180 disease pathogenesis. This was accompanied by an increase in levels of the L-type Ca(2+)-channel, which is implicated in pathological hypertrophy. When Tm180 mice were crossed with a PMCA4-null line, loss of PMCA4 caused the abrogation of hypertrophy in Tm180/PMCA4-null double mutant mice. RT-PCR analysis of Tm180/PMCA4-null hearts revealed blunting of the fetal program and reversion of pro-fibrotic Col1a1 and Col3a1 gene expression to wild-type levels. This was accompanied by evidence of reduced L-type Ca(2+)-channel expression, and diminished calcineurin activity. Expression of the metabolic substrate transporters glucose transporter 4 and carnitine palmitoyltransferase 1b was preserved and Tm180-related changes in mRNA levels of various contractile stress-related proteins including the cardiac ankyrin protein CARP and the N2B isoform of titin were reversed in Tm180/PMCA4-null hearts. cGMP levels were increased and phosphorylation of vasodilator-stimulated phosphoprotein was elevated in Tm180/PMCA4-null hearts. These changes were associated with a sharp reduction in left ventricular end-diastolic pressure in Tm180/PMCA4-null hearts, which occurred despite persistence of Tm180-related impairment of relaxation dynamics. These results reveal a novel and specific role for PMCA4 in the Tm180 hypertrophic phenotype, with the "protective" effects of PMCA4 deficiency encompassing multiple determinants of HCM-related hypertrophy.
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22
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Alves ML, Dias FAL, Gaffin RD, Simon JN, Montminy EM, Biesiadecki BJ, Hinken AC, Warren CM, Utter MS, Davis RT, Sakthivel S, Robbins J, Wieczorek DF, Solaro RJ, Wolska BM. Desensitization of myofilaments to Ca2+ as a therapeutic target for hypertrophic cardiomyopathy with mutations in thin filament proteins. ACTA ACUST UNITED AC 2014; 7:132-143. [PMID: 24585742 DOI: 10.1161/circgenetics.113.000324] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
BACKGROUND Hypertrophic cardiomyopathy (HCM) is a common genetic disorder caused mainly by mutations in sarcomeric proteins and is characterized by maladaptive myocardial hypertrophy, diastolic heart failure, increased myofilament Ca(2+) sensitivity, and high susceptibility to sudden death. We tested the following hypothesis: correction of the increased myofilament sensitivity can delay or prevent the development of the HCM phenotype. METHODS AND RESULTS We used an HCM mouse model with an E180G mutation in α-tropomyosin (Tm180) that demonstrates increased myofilament Ca(2+) sensitivity, severe hypertrophy, and diastolic dysfunction. To test our hypothesis, we reduced myofilament Ca(2+) sensitivity in Tm180 mice by generating a double transgenic mouse line. We crossed Tm180 mice with mice expressing a pseudophosphorylated cardiac troponin I (S23D and S24D; TnI-PP). TnI-PP mice demonstrated a reduced myofilament Ca(2+) sensitivity compared with wild-type mice. The development of pathological hypertrophy did not occur in mice expressing both Tm180 and TnI-PP. Left ventricle performance was improved in double transgenic compared with their Tm180 littermates, which express wild-type cardiac troponin I. Hearts of double transgenic mice demonstrated no changes in expression of phospholamban and sarcoplasmic reticulum Ca(2+) ATPase, increased levels of phospholamban and troponin T phosphorylation, and reduced phosphorylation of TnI compared with Tm180 mice. Moreover, expression of TnI-PP in Tm180 hearts inhibited modifications in the activity of extracellular signal-regulated kinase and zinc finger-containing transcription factor GATA in Tm180 hearts. CONCLUSIONS Our data strongly indicate that reduction of myofilament sensitivity to Ca(2+) and associated correction of abnormal relaxation can delay or prevent development of HCM and should be considered as a therapeutic target for HCM.
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Affiliation(s)
- Marco L Alves
- Department of Physiology and Biophysics, Center for Cardiovascular Research, University of Illinois, Chicago, IL.,Department of Physiology and Department of Cell Biology, Federal University of Parana, Curitiba, Brazil
| | - Fernando A L Dias
- Department of Physiology and Biophysics, Center for Cardiovascular Research, University of Illinois, Chicago, IL.,Department of Physiology and Department of Cell Biology, Federal University of Parana, Curitiba, Brazil
| | - Robert D Gaffin
- Department of Physiology and Biophysics, Center for Cardiovascular Research, University of Illinois, Chicago, IL
| | - Jillian N Simon
- Department of Physiology and Biophysics, Center for Cardiovascular Research, University of Illinois, Chicago, IL
| | - Eric M Montminy
- Department of Physiology and Biophysics, Center for Cardiovascular Research, University of Illinois, Chicago, IL
| | - Brandon J Biesiadecki
- Department of Physiology and Biophysics, Center for Cardiovascular Research, University of Illinois, Chicago, IL.,Department of Physiology and Cell Biology, The Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH
| | - Aaron C Hinken
- Department of Physiology and Biophysics, Center for Cardiovascular Research, University of Illinois, Chicago, IL
| | - Chad M Warren
- Department of Physiology and Biophysics, Center for Cardiovascular Research, University of Illinois, Chicago, IL
| | - Megan S Utter
- Department of Physiology and Biophysics, Center for Cardiovascular Research, University of Illinois, Chicago, IL
| | - Robert T Davis
- Department of Physiology and Biophysics, Center for Cardiovascular Research, University of Illinois, Chicago, IL
| | - Sadayappan Sakthivel
- Division of Molecular Cardiovascular Biology, Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati
| | - Jeffrey Robbins
- Division of Molecular Cardiovascular Biology, Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati
| | - David F Wieczorek
- Department of Molecular Genetics, Biochemistry and Microbiology, University of Cincinnati, College of Medicine
| | - R John Solaro
- Department of Physiology and Biophysics, Center for Cardiovascular Research, University of Illinois, Chicago, IL
| | - Beata M Wolska
- Department of Medicine, Section of Cardiology, University of Illinois, Chicago, IL.,Department of Physiology and Biophysics, Center for Cardiovascular Research, University of Illinois, Chicago, IL
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23
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Schulz EM, Wilder T, Chowdhury SAK, Sheikh HN, Wolska BM, Solaro RJ, Wieczorek DF. Decreasing tropomyosin phosphorylation rescues tropomyosin-induced familial hypertrophic cardiomyopathy. J Biol Chem 2013; 288:28925-35. [PMID: 23960072 DOI: 10.1074/jbc.m113.466466] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Studies indicate that tropomyosin (Tm) phosphorylation status varies in different mouse models of cardiac disease. Investigation of basal and acute cardiac function utilizing a mouse model expressing an α-Tm protein that cannot be phosphorylated (S283A) shows a compensated hypertrophic phenotype with significant increases in SERCA2a expression and phosphorylation of phospholamban Ser-16 (Schulz, E. M., Correll, R. N., Sheikh, H. N., Lofrano-Alves, M. S., Engel, P. L., Newman, G., Schultz Jel, J., Molkentin, J. D., Wolska, B. M., Solaro, R. J., and Wieczorek, D. F. (2012) J. Biol. Chem. 287, 44478-44489). With these results, we hypothesized that decreasing α-Tm phosphorylation may be beneficial in the context of a chronic, intrinsic stressor. To test this hypothesis, we utilized the familial hypertrophic cardiomyopathy (FHC) α-Tm E180G model (Prabhakar, R., Boivin, G. P., Grupp, I. L., Hoit, B., Arteaga, G., Solaro, R. J., and Wieczorek, D. F. (2001) J. Mol. Cell. Cardiol. 33, 1815-1828). These FHC hearts are characterized by increased heart:body weight ratios, fibrosis, increased myofilament Ca(2+) sensitivity, and contractile defects. The FHC mice die by 6-8 months of age. We generated mice expressing both the E180G and S283A mutations and found that the hypertrophic phenotype was rescued in the α-Tm E180G/S283A double mutant transgenic animals; these mice exhibited no signs of cardiac hypertrophy and displayed improved cardiac function. These double mutant transgenic hearts showed increased phosphorylation of phospholamban Ser-16 and Thr-17 compared with the α-Tm E180G mice. This is the first study to demonstrate that decreasing phosphorylation of tropomyosin can rescue a hypertrophic cardiomyopathic phenotype.
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Affiliation(s)
- Emily M Schulz
- From the Department of Molecular Genetics, Biochemistry, and Microbiology, University of Cincinnati College of Medicine, Cincinnati, Ohio 45267
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24
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Passariello CL, Gayanilo M, Kritzer MD, Thakur H, Cozacov Z, Rusconi F, Wieczorek D, Sanders M, Li J, Kapiloff MS. p90 ribosomal S6 kinase 3 contributes to cardiac insufficiency in α-tropomyosin Glu180Gly transgenic mice. Am J Physiol Heart Circ Physiol 2013; 305:H1010-9. [PMID: 23913705 DOI: 10.1152/ajpheart.00237.2013] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Myocardial interstitial fibrosis is an important contributor to the development of heart failure. Type 3 p90 ribosomal S6 kinase (RSK3) was recently shown to be required for concentric myocyte hypertrophy under in vivo pathological conditions. However, the role of RSK family members in myocardial fibrosis remains uninvestigated. Transgenic expression of α-tropomyosin containing a Glu180Gly mutation (TM180) in mice of a mixed C57BL/6:FVB/N background induces a cardiomyopathy characterized by a small left ventricle, interstitial fibrosis, and diminished systolic and diastolic function. Using this mouse model, we now show that RSK3 is required for the induction of interstitial fibrosis in vivo. TM180 transgenic mice were crossed to RSK3 constitutive knockout (RSK3(-/-)) mice. Although RSK3 knockout did not affect myocyte growth, the decreased cardiac function and mild pulmonary edema associated with the TM180 transgene were attenuated by RSK3 knockout. The improved cardiac function was consistent with reduced interstitial fibrosis in the TM180;RSK3(-/-) mice as shown by histology and gene expression analysis, including the decreased expression of collagens. The specific inhibition of RSK3 should be considered as a potential novel therapeutic strategy for improving cardiac function and the prevention of sudden cardiac death in diseases in which interstitial fibrosis contributes to the development of heart failure.
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Affiliation(s)
- Catherine L Passariello
- Cardiac Signal Transduction and Cellular Biology Laboratory, Interdisciplinary Stem Cell Institute, Departments of Pediatrics and Medicine, Leonard M. Miller School of Medicine, University of Miami, Miami, Florida; and
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25
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Rajan S, Pena JR, Jegga AG, Aronow BJ, Wolska BM, Wieczorek DF. Microarray analysis of active cardiac remodeling genes in a familial hypertrophic cardiomyopathy mouse model rescued by a phospholamban knockout. Physiol Genomics 2013; 45:764-73. [PMID: 23800848 DOI: 10.1152/physiolgenomics.00023.2013] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Familial hypertrophic cardiomyopathy (FHC) is a disease characterized by ventricular hypertrophy, fibrosis, and aberrant systolic and/or diastolic function. Our laboratories have previously developed two mouse models that affect cardiac performance. One mouse model encodes an FHC-associated mutation in α-tropomyosin: Glu → Gly at amino acid 180, designated as Tm180. These mice display a phenotype that is characteristic of FHC, including severe cardiac hypertrophy with fibrosis and impaired physiological performance. The other model was a gene knockout of phospholamban (PLN KO), a regulator of calcium uptake in the sarcoplasmic reticulum of cardiomyocytes; these hearts exhibit hypercontractility with no pathological abnormalities. Previous work in our laboratories shows that when mice were genetically crossed between the PLN KO and Tm180, the progeny (PLN KO/Tm180) display a rescued hypertrophic phenotype with improved morphology and cardiac function. To understand the changes in gene expression that occur in these models undergoing cardiac remodeling (Tm180, PLN KO, PLN KO/Tm180, and nontransgenic control mice), we conducted microarray analyses of left ventricular tissue at 4 and 12 mo of age. Expression profiling reveals that 1,187 genes changed expression in direct response to the three genetic models. With these 1,187 genes, 11 clusters emerged showing normalization of transcript expression in the PLN KO/Tm180 hearts. In addition, 62 transcripts are highly involved in suppression of the hypertrophic phenotype. Confirmation of the microarray analysis was conducted by quantitative RT-PCR. These results provide insight into genes that alter expression during cardiac remodeling and are active during modulation of the cardiomyopathic phenotype.
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Affiliation(s)
- Sudarsan Rajan
- Department of Molecular Genetics, Biochemistry, & Microbiology, University of Cincinnati College of Medicine, Cincinnati, OH 45267-0524, USA
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26
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Schulz EM, Wieczorek DF. Tropomyosin de-phosphorylation in the heart: What are the consequences? J Muscle Res Cell Motil 2013; 34:239-46. [DOI: 10.1007/s10974-013-9348-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2013] [Accepted: 05/24/2013] [Indexed: 11/30/2022]
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27
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Yar S, Chowdhury SAK, Davis RT, Kobayashi M, Monasky MM, Rajan S, Wolska BM, Gaponenko V, Kobayashi T, Wieczorek DF, Solaro RJ. Conserved Asp-137 is important for both structure and regulatory functions of cardiac α-tropomyosin (α-TM) in a novel transgenic mouse model expressing α-TM-D137L. J Biol Chem 2013; 288:16235-16246. [PMID: 23609439 DOI: 10.1074/jbc.m113.458695] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
α-Tropomyosin (α-TM) has a conserved, charged Asp-137 residue located in the hydrophobic core of its coiled-coil structure, which is unusual in that the residue is found at a position typically occupied by a hydrophobic residue. Asp-137 is thought to destabilize the coiled-coil and so impart structural flexibility to the molecule, which is believed to be crucial for its function in the heart. A previous in vitro study indicated that the conversion of Asp-137 to a more typical canonical Leu alters flexibility of TM and affects its in vitro regulatory functions. However, the physiological importance of the residue Asp-137 and altered TM flexibility is unknown. In this study, we further analyzed structural properties of the α-TM-D137L variant and addressed the physiological importance of TM flexibility in cardiac function in studies with a novel transgenic mouse model expressing α-TM-D137L in the heart. Our NMR spectroscopy data indicated that the presence of D137L introduced long range rearrangements in TM structure. Differential scanning calorimetry measurements demonstrated that α-TM-D137L has higher thermal stability compared with α-TM, which correlated with decreased flexibility. Hearts of transgenic mice expressing α-TM-D137L showed systolic and diastolic dysfunction with decreased myofilament Ca(2+) sensitivity and cardiomyocyte contractility without changes in intracellular Ca(2+) transients or post-translational modifications of major myofilament proteins. We conclude that conversion of the highly conserved Asp-137 to Leu results in loss of flexibility of TM that is important for its regulatory functions in mouse hearts. Thus, our results provide insight into the link between flexibility of TM and its function in ejecting hearts.
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Affiliation(s)
- Sumeyye Yar
- Departments of Biochemistry and Molecular Genetics, Chicago, Illinois 60612; Physiology and Biophysics, Chicago, Illinois 60612
| | | | | | | | | | - Sudarsan Rajan
- Department of Molecular Genetics, Biochemistry, and Microbiology, University of Cincinnati College of Medicine, Cincinnati, Ohio 45267
| | - Beata M Wolska
- Physiology and Biophysics, Chicago, Illinois 60612; Medicine, Chicago, Illinois 60612; Center for Cardiovascular Research, University of Illinois, Chicago, Illinois 60612
| | - Vadim Gaponenko
- Departments of Biochemistry and Molecular Genetics, Chicago, Illinois 60612
| | - Tomoyoshi Kobayashi
- Physiology and Biophysics, Chicago, Illinois 60612; Center for Cardiovascular Research, University of Illinois, Chicago, Illinois 60612
| | - David F Wieczorek
- Department of Molecular Genetics, Biochemistry, and Microbiology, University of Cincinnati College of Medicine, Cincinnati, Ohio 45267
| | - R John Solaro
- Physiology and Biophysics, Chicago, Illinois 60612; Center for Cardiovascular Research, University of Illinois, Chicago, Illinois 60612.
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28
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Schulz EM, Correll RN, Sheikh HN, Lofrano-Alves MS, Engel PL, Newman G, Schultz JEJ, Molkentin JD, Wolska BM, Solaro RJ, Wieczorek DF. Tropomyosin dephosphorylation results in compensated cardiac hypertrophy. J Biol Chem 2012; 287:44478-89. [PMID: 23148217 DOI: 10.1074/jbc.m112.402040] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Phosphorylation of tropomyosin (Tm) has been shown to vary in mouse models of cardiac hypertrophy. Little is known about the in vivo role of Tm phosphorylation. This study examines the consequences of Tm dephosphorylation in the murine heart. Transgenic (TG) mice were generated with cardiac specific expression of α-Tm with serine 283, the phosphorylation site of Tm, mutated to alanine. Echocardiographic analysis and cardiomyocyte cross-sectional area measurements show that α-Tm S283A TG mice exhibit a hypertrophic phenotype at basal levels. Interestingly, there are no alterations in cardiac function, myofilament calcium (Ca(2+)) sensitivity, cooperativity, or response to β-adrenergic stimulus. Studies of Ca(2+) handling proteins show significant increases in sarcoplasmic reticulum ATPase (SERCA2a) protein expression and an increase in phospholamban phosphorylation at serine 16, similar to hearts under exercise training. Compared with controls, the decrease in phosphorylation of α-Tm results in greater functional defects in TG animals stressed by transaortic constriction to induce pressure overload-hypertrophy. This is the first study to investigate the in vivo role of Tm dephosphorylation under both normal and cardiac stress conditions, documenting a role for Tm dephosphorylation in the maintenance of a compensated or physiological phenotype. Collectively, these results suggest that modification of the Tm phosphorylation status in the heart, depending upon the cardiac state/condition, may modulate the development of cardiac hypertrophy.
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Affiliation(s)
- Emily M Schulz
- Department of Molecular Genetics, Biochemistry, and Microbiology, University of Cincinnati College of Medicine, Cincinnati, Ohio 45267, USA
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29
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Knöll R. Myosin binding protein C: implications for signal-transduction. J Muscle Res Cell Motil 2011; 33:31-42. [PMID: 22173300 PMCID: PMC3351598 DOI: 10.1007/s10974-011-9281-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2011] [Accepted: 11/28/2011] [Indexed: 12/29/2022]
Abstract
Myosin binding protein C (MYBPC) is a crucial component of the sarcomere and an important regulator of muscle function. While mutations in different myosin binding protein C (MYBPC) genes are well known causes of various human diseases, such as hypertrophic (HCM) and dilated (DCM) forms of cardiomyopathy as well as skeletal muscular disorders, the underlying molecular mechanisms remain not well understood. A variety of MYBPC3 (cardiac isoform) mutations have been studied in great detail and several corresponding genetically altered mouse models have been generated. Most MYBPC3 mutations may cause haploinsufficiency and with it they may cause a primary increase in calcium sensitivity which is potentially able to explain major features observed in HCM patients such as the hypercontractile phenotype and the well known secondary effects such as myofibrillar disarray, fibrosis, myocardial hypertrophy and remodelling including arrhythmogenesis. However the presence of poison peptides in some cases cannot be fully excluded and most probably other mechanisms are also at play. Here we shall discuss MYBPC interacting proteins and possible pathways linked to cardiomyopathy and heart failure.
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Affiliation(s)
- Ralph Knöll
- Imperial College, National Heart and Lung Institute, British Heart Foundation-Centre for Research Excellence, Myocardial Genetics, London, UK.
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