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Creso JG, Gokhan I, Rynkiewicz MJ, Lehman W, Moore JR, Campbell SG. In silico and in vitro models reveal the molecular mechanisms of hypocontractility caused by TPM1 M8R. Front Physiol 2024; 15:1452509. [PMID: 39282088 PMCID: PMC11392859 DOI: 10.3389/fphys.2024.1452509] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2024] [Accepted: 08/19/2024] [Indexed: 09/18/2024] Open
Abstract
Dilated cardiomyopathy (DCM) is an inherited disorder often leading to severe heart failure. Linkage studies in affected families have revealed hundreds of different mutations that can cause DCM, with most occurring in genes associated with the cardiac sarcomere. We have developed an investigational pipeline for discovering mechanistic genotype-phenotype relationships in DCM and here apply it to the DCM-linked tropomyosin mutation TPM1 M8R. Atomistic simulations predict that M8R increases flexibility of the tropomyosin chain and enhances affinity for the blocked or inactive state of tropomyosin on actin. Applying these molecular effects to a Markov model of the cardiac thin filament reproduced the shifts in Ca2+sensitivity, maximum force, and a qualitative drop in cooperativity that were observed in an in vitro system containing TPM1 M8R. The model was then used to simulate the impact of M8R expression on twitch contractions of intact cardiac muscle, predicting that M8R would reduce peak force and duration of contraction in a dose-dependent manner. To evaluate this prediction, TPM1 M8R was expressed via adenovirus in human engineered heart tissues and isometric twitch force was observed. The mutant tissues manifested depressed contractility and twitch duration that agreed in detail with model predictions. Additional exploratory simulations suggest that M8R-mediated alterations in tropomyosin-actin interactions contribute more potently than tropomyosin chain stiffness to cardiac twitch dysfunction, and presumably to the ultimate manifestation of DCM. This study is an example of the growing potential for successful in silico prediction of mutation pathogenicity for inherited cardiac muscle disorders.
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Affiliation(s)
- Jenette G Creso
- Department of Biomedical Engineering, Yale University, New Haven, CT, United States
| | - Ilhan Gokhan
- Department of Biomedical Engineering, Yale University, New Haven, CT, United States
| | - Michael J Rynkiewicz
- Department of Pharmacology, Physiology and Biophysics, Boston University Chobanian and Avedisian School of Medicine, Boston, MA, United States
| | - William Lehman
- Department of Pharmacology, Physiology and Biophysics, Boston University Chobanian and Avedisian School of Medicine, Boston, MA, United States
| | - Jeffrey R Moore
- Department of Biological Sciences, University of Massachusetts-Lowell, Lowell, MA, United States
| | - Stuart G Campbell
- Department of Biomedical Engineering, Yale University, New Haven, CT, United States
- Department of Cellular and Molecular Physiology, Yale School of Medicine, New Haven, CT, United States
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Malinow I, Fong DC, Miyamoto M, Badran S, Hong CC. Pediatric dilated cardiomyopathy: a review of current clinical approaches and pathogenesis. Front Pediatr 2024; 12:1404942. [PMID: 38966492 PMCID: PMC11223501 DOI: 10.3389/fped.2024.1404942] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/21/2024] [Accepted: 06/05/2024] [Indexed: 07/06/2024] Open
Abstract
Pediatric dilated cardiomyopathy (DCM) is a rare, yet life-threatening cardiovascular condition characterized by systolic dysfunction with biventricular dilatation and reduced myocardial contractility. Therapeutic options are limited with nearly 40% of children undergoing heart transplant or death within 2 years of diagnosis. Pediatric patients are currently diagnosed based on correlating the clinical picture with echocardiographic findings. Patient age, etiology of disease, and parameters of cardiac function significantly impact prognosis. Treatments for pediatric DCM aim to ameliorate symptoms, reduce progression of disease, and prevent life-threatening arrhythmias. Many therapeutic agents with known efficacy in adults lack the same evidence in children. Unlike adult DCM, the pathogenesis of pediatric DCM is not well understood as approximately two thirds of cases are classified as idiopathic disease. Children experience unique gene expression changes and molecular pathway activation in response to DCM. Studies have pointed to a significant genetic component in pediatric DCM, with variants in genes related to sarcomere and cytoskeleton structure implicated. In this regard, pediatric DCM can be considered pediatric manifestations of inherited cardiomyopathy syndromes. Yet exciting recent studies in infantile DCM suggest that this subset has a distinct etiology involving defective postnatal cardiac maturation, such as the failure of programmed centrosome breakdown in cardiomyocytes. Improved knowledge of pathogenesis is central to developing child-specific treatment approaches. This review aims to discuss the established biological pathogenesis of pediatric DCM, current clinical guidelines, and promising therapeutic avenues, highlighting differences from adult disease. The overarching goal is to unravel the complexities surrounding this condition to facilitate the advancement of novel therapeutic interventions and improve prognosis and overall quality of life for pediatric patients affected by DCM.
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Affiliation(s)
- Ian Malinow
- Division of Cardiovascular Medicine, Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, United States
| | - Daniel C. Fong
- Division of Cardiovascular Medicine, Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, United States
| | - Matthew Miyamoto
- Division of Cardiovascular Medicine, Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, United States
| | - Sarah Badran
- Department of Pediatric Cardiology, Michigan State University College of Human Medicine Helen Devos Children’s Hospital, Grand Rapids, MI, United States
| | - Charles C. Hong
- Department of Medicine, Division of Cardiology, Michigan State University College of Human Medicine, East Lansing, MI, United States
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3
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Vahle B, Heilmann L, Schauer A, Augstein A, Jarabo MEP, Barthel P, Mangner N, Labeit S, Bowen TS, Linke A, Adams V. Modulation of Titin and Contraction-Regulating Proteins in a Rat Model of Heart Failure with Preserved Ejection Fraction: Limb vs. Diaphragmatic Muscle. Int J Mol Sci 2024; 25:6618. [PMID: 38928324 PMCID: PMC11203682 DOI: 10.3390/ijms25126618] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2024] [Revised: 06/12/2024] [Accepted: 06/14/2024] [Indexed: 06/28/2024] Open
Abstract
Heart failure with preserved ejection fraction (HFpEF) is characterized by biomechanically dysfunctional cardiomyocytes. Underlying cellular changes include perturbed myocardial titin expression and titin hypophosphorylation leading to titin filament stiffening. Beside these well-studied alterations at the cardiomyocyte level, exercise intolerance is another hallmark of HFpEF caused by molecular alterations in skeletal muscle (SKM). Currently, there is a lack of data regarding titin modulation in the SKM of HFpEF. Therefore, the aim of the present study was to analyze molecular alterations in limb SKM (tibialis anterior (TA)) and in the diaphragm (Dia), as a more central SKM, with a focus on titin, titin phosphorylation, and contraction-regulating proteins. This study was performed with muscle tissue, obtained from 32-week old female ZSF-1 rats, an established a HFpEF rat model. Our results showed a hyperphosphorylation of titin in limb SKM, based on enhanced phosphorylation at the PEVK region, which is known to lead to titin filament stiffening. This hyperphosphorylation could be reversed by high-intensity interval training (HIIT). Additionally, a negative correlation occurring between the phosphorylation state of titin and the muscle force in the limb SKM was evident. For the Dia, no alterations in the phosphorylation state of titin could be detected. Supported by data of previous studies, this suggests an exercise effect of the Dia in HFpEF. Regarding the expression of contraction regulating proteins, significant differences between Dia and limb SKM could be detected, supporting muscle atrophy and dysfunction in limb SKM, but not in the Dia. Altogether, these data suggest a correlation between titin stiffening and the appearance of exercise intolerance in HFpEF, as well as a differential regulation between different SKM groups.
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Affiliation(s)
- Beatrice Vahle
- Heart Center Dresden, Laboratory of Molecular and Experimental Cardiology, TU Dresden, 01307 Dresden, Germany; (B.V.); (L.H.); (A.S.); (A.A.); (M.-E.P.J.); (P.B.); (N.M.); (A.L.)
| | - Leonard Heilmann
- Heart Center Dresden, Laboratory of Molecular and Experimental Cardiology, TU Dresden, 01307 Dresden, Germany; (B.V.); (L.H.); (A.S.); (A.A.); (M.-E.P.J.); (P.B.); (N.M.); (A.L.)
| | - Antje Schauer
- Heart Center Dresden, Laboratory of Molecular and Experimental Cardiology, TU Dresden, 01307 Dresden, Germany; (B.V.); (L.H.); (A.S.); (A.A.); (M.-E.P.J.); (P.B.); (N.M.); (A.L.)
| | - Antje Augstein
- Heart Center Dresden, Laboratory of Molecular and Experimental Cardiology, TU Dresden, 01307 Dresden, Germany; (B.V.); (L.H.); (A.S.); (A.A.); (M.-E.P.J.); (P.B.); (N.M.); (A.L.)
| | - Maria-Elisa Prieto Jarabo
- Heart Center Dresden, Laboratory of Molecular and Experimental Cardiology, TU Dresden, 01307 Dresden, Germany; (B.V.); (L.H.); (A.S.); (A.A.); (M.-E.P.J.); (P.B.); (N.M.); (A.L.)
| | - Peggy Barthel
- Heart Center Dresden, Laboratory of Molecular and Experimental Cardiology, TU Dresden, 01307 Dresden, Germany; (B.V.); (L.H.); (A.S.); (A.A.); (M.-E.P.J.); (P.B.); (N.M.); (A.L.)
| | - Norman Mangner
- Heart Center Dresden, Laboratory of Molecular and Experimental Cardiology, TU Dresden, 01307 Dresden, Germany; (B.V.); (L.H.); (A.S.); (A.A.); (M.-E.P.J.); (P.B.); (N.M.); (A.L.)
| | - Siegfried Labeit
- DZHK Partner Site Mannheim-Heidelberg, Medical Faculty Mannheim, University of Heidelberg, 68169 Mannheim, Germany;
- Myomedix GmbH, 69151 Neckargemünd, Germany
| | - T. Scott Bowen
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK;
| | - Axel Linke
- Heart Center Dresden, Laboratory of Molecular and Experimental Cardiology, TU Dresden, 01307 Dresden, Germany; (B.V.); (L.H.); (A.S.); (A.A.); (M.-E.P.J.); (P.B.); (N.M.); (A.L.)
| | - Volker Adams
- Heart Center Dresden, Laboratory of Molecular and Experimental Cardiology, TU Dresden, 01307 Dresden, Germany; (B.V.); (L.H.); (A.S.); (A.A.); (M.-E.P.J.); (P.B.); (N.M.); (A.L.)
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4
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Dai Y, Ignatyeva N, Xu H, Wali R, Toischer K, Brandenburg S, Lenz C, Pronto J, Fakuade FE, Sossalla S, Zeisberg EM, Janshoff A, Kutschka I, Voigt N, Urlaub H, Rasmussen TB, Mogensen J, Lehnart SE, Hasenfuss G, Ebert A. An Alternative Mechanism of Subcellular Iron Uptake Deficiency in Cardiomyocytes. Circ Res 2023; 133:e19-e46. [PMID: 37313752 DOI: 10.1161/circresaha.122.321157] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/05/2022] [Accepted: 05/26/2023] [Indexed: 06/15/2023]
Abstract
BACKGROUND Systemic defects in intestinal iron absorption, circulation, and retention cause iron deficiency in 50% of patients with heart failure. Defective subcellular iron uptake mechanisms that are independent of systemic absorption are incompletely understood. The main intracellular route for iron uptake in cardiomyocytes is clathrin-mediated endocytosis. METHODS We investigated subcellular iron uptake mechanisms in patient-derived and CRISPR/Cas-edited induced pluripotent stem cell-derived cardiomyocytes as well as patient-derived heart tissue. We used an integrated platform of DIA-MA (mass spectrometry data-independent acquisition)-based proteomics and signaling pathway interrogation. We employed a genetic induced pluripotent stem cell model of 2 inherited mutations (TnT [troponin T]-R141W and TPM1 [tropomyosin 1]-L185F) that lead to dilated cardiomyopathy (DCM), a frequent cause of heart failure, to study the underlying molecular dysfunctions of DCM mutations. RESULTS We identified a druggable molecular pathomechanism of impaired subcellular iron deficiency that is independent of systemic iron metabolism. Clathrin-mediated endocytosis defects as well as impaired endosome distribution and cargo transfer were identified as a basis for subcellular iron deficiency in DCM-induced pluripotent stem cell-derived cardiomyocytes. The clathrin-mediated endocytosis defects were also confirmed in the hearts of patients with DCM with end-stage heart failure. Correction of the TPM1-L185F mutation in DCM patient-derived induced pluripotent stem cells, treatment with a peptide, Rho activator II, or iron supplementation rescued the molecular disease pathway and recovered contractility. Phenocopying the effects of the TPM1-L185F mutation into WT induced pluripotent stem cell-derived cardiomyocytes could be ameliorated by iron supplementation. CONCLUSIONS Our findings suggest that impaired endocytosis and cargo transport resulting in subcellular iron deficiency could be a relevant pathomechanism for patients with DCM carrying inherited mutations. Insight into this molecular mechanism may contribute to the development of treatment strategies and risk management in heart failure.
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Affiliation(s)
- Yuanyuan Dai
- Heart Research Center Goettingen, Clinic for Cardiology and Pneumology, University Medical Center Goettingen, Georg-August University of Goettingen, Germany (Y.D., N.I., H.X., R.W., K.T., S.B., S.S., E.M.Z., S.E.L., G.H., A.E.)
- DZHK (German Center for Cardiovascular Research), partner site Goettingen, Germany (Y.D., N.I., H.X., R.W., K.T., S.B., C.L., J.P., F.E.F., E.M.Z., I.K., N.V., S.E.L., G.H., A.E.)
| | - Nadezda Ignatyeva
- Heart Research Center Goettingen, Clinic for Cardiology and Pneumology, University Medical Center Goettingen, Georg-August University of Goettingen, Germany (Y.D., N.I., H.X., R.W., K.T., S.B., S.S., E.M.Z., S.E.L., G.H., A.E.)
- DZHK (German Center for Cardiovascular Research), partner site Goettingen, Germany (Y.D., N.I., H.X., R.W., K.T., S.B., C.L., J.P., F.E.F., E.M.Z., I.K., N.V., S.E.L., G.H., A.E.)
| | - Hang Xu
- Heart Research Center Goettingen, Clinic for Cardiology and Pneumology, University Medical Center Goettingen, Georg-August University of Goettingen, Germany (Y.D., N.I., H.X., R.W., K.T., S.B., S.S., E.M.Z., S.E.L., G.H., A.E.)
- DZHK (German Center for Cardiovascular Research), partner site Goettingen, Germany (Y.D., N.I., H.X., R.W., K.T., S.B., C.L., J.P., F.E.F., E.M.Z., I.K., N.V., S.E.L., G.H., A.E.)
| | - Ruheen Wali
- Heart Research Center Goettingen, Clinic for Cardiology and Pneumology, University Medical Center Goettingen, Georg-August University of Goettingen, Germany (Y.D., N.I., H.X., R.W., K.T., S.B., S.S., E.M.Z., S.E.L., G.H., A.E.)
- DZHK (German Center for Cardiovascular Research), partner site Goettingen, Germany (Y.D., N.I., H.X., R.W., K.T., S.B., C.L., J.P., F.E.F., E.M.Z., I.K., N.V., S.E.L., G.H., A.E.)
| | - Karl Toischer
- Heart Research Center Goettingen, Clinic for Cardiology and Pneumology, University Medical Center Goettingen, Georg-August University of Goettingen, Germany (Y.D., N.I., H.X., R.W., K.T., S.B., S.S., E.M.Z., S.E.L., G.H., A.E.)
- DZHK (German Center for Cardiovascular Research), partner site Goettingen, Germany (Y.D., N.I., H.X., R.W., K.T., S.B., C.L., J.P., F.E.F., E.M.Z., I.K., N.V., S.E.L., G.H., A.E.)
- Heart Center, Clinic for Cardiology and Pneumology, University Medical Center Goettingen (K.T., S.B., S.S., G.H.), University of Goettingen, Germany
| | - Sören Brandenburg
- Heart Research Center Goettingen, Clinic for Cardiology and Pneumology, University Medical Center Goettingen, Georg-August University of Goettingen, Germany (Y.D., N.I., H.X., R.W., K.T., S.B., S.S., E.M.Z., S.E.L., G.H., A.E.)
- DZHK (German Center for Cardiovascular Research), partner site Goettingen, Germany (Y.D., N.I., H.X., R.W., K.T., S.B., C.L., J.P., F.E.F., E.M.Z., I.K., N.V., S.E.L., G.H., A.E.)
- Heart Center, Clinic for Cardiology and Pneumology, University Medical Center Goettingen (K.T., S.B., S.S., G.H.), University of Goettingen, Germany
| | - Christof Lenz
- DZHK (German Center for Cardiovascular Research), partner site Goettingen, Germany (Y.D., N.I., H.X., R.W., K.T., S.B., C.L., J.P., F.E.F., E.M.Z., I.K., N.V., S.E.L., G.H., A.E.)
- Department of Clinical Chemistry, University Medical Center Goettingen, (C.L., H.U.), University of Goettingen, Germany
- Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC; C.L., F.E.F., N.V., S.E.L.), University of Goettingen, Germany
- Bioanalytical Mass Spectrometry, Max Planck Institute for Multidisciplinary Sciences, Goettingen (C.L., H.U.)
| | - Julius Pronto
- DZHK (German Center for Cardiovascular Research), partner site Goettingen, Germany (Y.D., N.I., H.X., R.W., K.T., S.B., C.L., J.P., F.E.F., E.M.Z., I.K., N.V., S.E.L., G.H., A.E.)
- Institute of Pharmacology and Toxicology, University Medical Center Goettingen, (J.P., F.E.F., N.V.), University of Goettingen, Germany
| | - Funsho E Fakuade
- DZHK (German Center for Cardiovascular Research), partner site Goettingen, Germany (Y.D., N.I., H.X., R.W., K.T., S.B., C.L., J.P., F.E.F., E.M.Z., I.K., N.V., S.E.L., G.H., A.E.)
- Institute of Pharmacology and Toxicology, University Medical Center Goettingen, (J.P., F.E.F., N.V.), University of Goettingen, Germany
- Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC; C.L., F.E.F., N.V., S.E.L.), University of Goettingen, Germany
| | - Samuel Sossalla
- Heart Research Center Goettingen, Clinic for Cardiology and Pneumology, University Medical Center Goettingen, Georg-August University of Goettingen, Germany (Y.D., N.I., H.X., R.W., K.T., S.B., S.S., E.M.Z., S.E.L., G.H., A.E.)
- Heart Center, Clinic for Cardiology and Pneumology, University Medical Center Goettingen (K.T., S.B., S.S., G.H.), University of Goettingen, Germany
- Department for Internal Medicine II, University Medical Center Regensburg (S.S.)
| | - Elisabeth M Zeisberg
- Heart Research Center Goettingen, Clinic for Cardiology and Pneumology, University Medical Center Goettingen, Georg-August University of Goettingen, Germany (Y.D., N.I., H.X., R.W., K.T., S.B., S.S., E.M.Z., S.E.L., G.H., A.E.)
- DZHK (German Center for Cardiovascular Research), partner site Goettingen, Germany (Y.D., N.I., H.X., R.W., K.T., S.B., C.L., J.P., F.E.F., E.M.Z., I.K., N.V., S.E.L., G.H., A.E.)
| | - Andreas Janshoff
- Institute for Physical Chemistry (A.J.), University of Goettingen, Germany
| | - Ingo Kutschka
- DZHK (German Center for Cardiovascular Research), partner site Goettingen, Germany (Y.D., N.I., H.X., R.W., K.T., S.B., C.L., J.P., F.E.F., E.M.Z., I.K., N.V., S.E.L., G.H., A.E.)
- Department of Thoracic and Cardiovascular Surgery, University Medical Center Göttingen (I.K.)
| | - Niels Voigt
- DZHK (German Center for Cardiovascular Research), partner site Goettingen, Germany (Y.D., N.I., H.X., R.W., K.T., S.B., C.L., J.P., F.E.F., E.M.Z., I.K., N.V., S.E.L., G.H., A.E.)
- Institute of Pharmacology and Toxicology, University Medical Center Goettingen, (J.P., F.E.F., N.V.), University of Goettingen, Germany
- Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC; C.L., F.E.F., N.V., S.E.L.), University of Goettingen, Germany
| | - Henning Urlaub
- Department of Clinical Chemistry, University Medical Center Goettingen, (C.L., H.U.), University of Goettingen, Germany
- Bioanalytical Mass Spectrometry, Max Planck Institute for Multidisciplinary Sciences, Goettingen (C.L., H.U.)
| | | | - Jens Mogensen
- Department of Cardiology, Aalborg University Hospital, Denmark (J.M.)
| | - Stephan E Lehnart
- Heart Research Center Goettingen, Clinic for Cardiology and Pneumology, University Medical Center Goettingen, Georg-August University of Goettingen, Germany (Y.D., N.I., H.X., R.W., K.T., S.B., S.S., E.M.Z., S.E.L., G.H., A.E.)
- DZHK (German Center for Cardiovascular Research), partner site Goettingen, Germany (Y.D., N.I., H.X., R.W., K.T., S.B., C.L., J.P., F.E.F., E.M.Z., I.K., N.V., S.E.L., G.H., A.E.)
- Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC; C.L., F.E.F., N.V., S.E.L.), University of Goettingen, Germany
| | - Gerd Hasenfuss
- Heart Research Center Goettingen, Clinic for Cardiology and Pneumology, University Medical Center Goettingen, Georg-August University of Goettingen, Germany (Y.D., N.I., H.X., R.W., K.T., S.B., S.S., E.M.Z., S.E.L., G.H., A.E.)
- DZHK (German Center for Cardiovascular Research), partner site Goettingen, Germany (Y.D., N.I., H.X., R.W., K.T., S.B., C.L., J.P., F.E.F., E.M.Z., I.K., N.V., S.E.L., G.H., A.E.)
- Heart Center, Clinic for Cardiology and Pneumology, University Medical Center Goettingen (K.T., S.B., S.S., G.H.), University of Goettingen, Germany
| | - Antje Ebert
- Heart Research Center Goettingen, Clinic for Cardiology and Pneumology, University Medical Center Goettingen, Georg-August University of Goettingen, Germany (Y.D., N.I., H.X., R.W., K.T., S.B., S.S., E.M.Z., S.E.L., G.H., A.E.)
- DZHK (German Center for Cardiovascular Research), partner site Goettingen, Germany (Y.D., N.I., H.X., R.W., K.T., S.B., C.L., J.P., F.E.F., E.M.Z., I.K., N.V., S.E.L., G.H., A.E.)
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5
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Yang C, Chen F, Li S, Zeng X, Wang S, Lan J. Association of rs35006907 Polymorphism with Risk of Dilated Cardiomyopathy in Han Chinese Population. Balkan J Med Genet 2023; 26:27-34. [PMID: 38711908 PMCID: PMC11071056 DOI: 10.2478/bjmg-2023-0004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/08/2024] Open
Abstract
Background Several investigations have demonstrated the association of MTSS1 with left ventricular (LV) structure and function. A recently published study has even revealed that rs35006907 was associated with both MTSS1 expression and the risk of dilated cardiomyopathy (DCM). Objective Our study intended to investigate the relationship between rs35006907 and the risk of DCM in the Han Chinese population. Methods A total of 529 DCM and 600 healthy controls were recruited. We conducted genotyping for rs35006907 in all participants. Gene association studies were performed to assess the association between rs35006907 and the risk of DCM. A series of functional assays including western blot, realtime PCR and firefly luciferase reporter gene assays were conducted to illuminate the underlying mechanism. Results We found that rs35006907-A allele was significantly associated with reduced risk of DCM in additive (p= 0.004; OR=0.78; 95% CI=0.66-0.93) and recessive models (p= 0.0005; OR=0.56; 95%CI=0.41-0.78) when compared with the rs35006907-C allele. There were significant differences in the left ventricular end-diastolic diameter (LVEDD) and left ventricular ejection fraction (LVEF) between rs35006907-CC/AC and AA genotypes. Furthermore, the variant rs35006907-A allele presented lower reporter gene activity, reduced mRNA and protein expression levels when compared with the C allele. Conclusions Our findings demonstrated that rs35006907-C allele increased the risk of DCM in Han Chinese population. Besides, rs35006907-C displayed higher reporter gene activity and increased MTSS1 expression in human samples.
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Affiliation(s)
- C Yang
- Division of Cardiology, Panzhihua Central Hospital, Panzhihua, China
| | - F Chen
- Department of Hematology, Panzhihua Central Hospital, Panzhihua, China
| | - Sh Li
- Division of Cardiology, Panzhihua Central Hospital, Panzhihua, China
| | - X Zeng
- Division of Cardiology, Panzhihua Central Hospital, Panzhihua, China
| | - Sh Wang
- Division of Cardiology, Panzhihua Central Hospital, Panzhihua, China
| | - J Lan
- Division of Cardiology, Panzhihua Central Hospital, Panzhihua, China
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Abstract
Heart disease is a significant burden on global health care systems and is a leading cause of death each year. To improve our understanding of heart disease, high quality disease models are needed. These will facilitate the discovery and development of new treatments for heart disease. Traditionally, researchers have relied on 2D monolayer systems or animal models of heart disease to elucidate pathophysiology and drug responses. Heart-on-a-chip (HOC) technology is an emerging field where cardiomyocytes among other cell types in the heart can be used to generate functional, beating cardiac microtissues that recapitulate many features of the human heart. HOC models are showing great promise as disease modeling platforms and are poised to serve as important tools in the drug development pipeline. By leveraging advances in human pluripotent stem cell-derived cardiomyocyte biology and microfabrication technology, diseased HOCs are highly tuneable and can be generated via different approaches such as: using cells with defined genetic backgrounds (patient-derived cells), adding small molecules, modifying the cells' environment, altering cell ratio/composition of microtissues, among others. HOCs have been used to faithfully model aspects of arrhythmia, fibrosis, infection, cardiomyopathies, and ischemia, to name a few. In this review, we highlight recent advances in disease modeling using HOC systems, describing instances where these models outperformed other models in terms of reproducing disease phenotypes and/or led to drug development.
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Affiliation(s)
- Omar Mourad
- Toronto General Hospital Research Institute (O.M., R.Y., M.L., S.S.N.), University Health Network, Toronto, Canada.,Institute of Biomedical Engineering (O.M., R.Y., M.L., S.S.N.), University of Toronto, Canada
| | - Ryan Yee
- Toronto General Hospital Research Institute (O.M., R.Y., M.L., S.S.N.), University Health Network, Toronto, Canada.,Institute of Biomedical Engineering (O.M., R.Y., M.L., S.S.N.), University of Toronto, Canada
| | - Mengyuan Li
- Toronto General Hospital Research Institute (O.M., R.Y., M.L., S.S.N.), University Health Network, Toronto, Canada.,Institute of Biomedical Engineering (O.M., R.Y., M.L., S.S.N.), University of Toronto, Canada
| | - Sara S Nunes
- Toronto General Hospital Research Institute (O.M., R.Y., M.L., S.S.N.), University Health Network, Toronto, Canada.,Ajmera Transplant Center (S.S.N.), University Health Network, Toronto, Canada.,Institute of Biomedical Engineering (O.M., R.Y., M.L., S.S.N.), University of Toronto, Canada.,Department of Laboratory Medicine and Pathobiology (S.S.N.), University of Toronto, Canada.,Heart and Stroke/Richard Lewar Centre of Excellence (S.S.N.), University of Toronto, Canada
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7
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Rayani K, Hantz ER, Haji-Ghassemi O, Li AY, Spuches AM, Van Petegem F, Solaro RJ, Lindert S, Tibbits GF. The effect of Mg 2+ on Ca 2+ binding to cardiac troponin C in hypertrophic cardiomyopathy associated TNNC1 variants. FEBS J 2022; 289:7446-7465. [PMID: 35838319 PMCID: PMC9836626 DOI: 10.1111/febs.16578] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Revised: 05/14/2022] [Accepted: 07/13/2022] [Indexed: 01/14/2023]
Abstract
Cardiac troponin C (cTnC) is the critical Ca2+ -sensing component of the troponin complex. Binding of Ca2+ to cTnC triggers a cascade of conformational changes within the myofilament that culminate in force production. Hypertrophic cardiomyopathy (HCM)-associated TNNC1 variants generally induce a greater degree and duration of Ca2+ binding, which may underly the hypertrophic phenotype. Regulation of contraction has long been thought to occur exclusively through Ca2+ binding to site II of cTnC. However, work by several groups including ours suggest that Mg2+ , which is several orders of magnitude more abundant in the cell than Ca2+ , may compete for binding to the same cTnC regulatory site. We previously used isothermal titration calorimetry (ITC) to demonstrate that physiological concentrations of Mg2+ may decrease site II Ca2+ -binding in both N-terminal and full-length cTnC. Here, we explore the binding of Ca2+ and Mg2+ to cTnC harbouring a series of TNNC1 variants thought to be causal in HCM. ITC and thermodynamic integration (TI) simulations show that A8V, L29Q and A31S elevate the affinity for both Ca2+ and Mg2+ . Further, L48Q, Q50R and C84Y that are adjacent to the EF hand binding motif of site II have a more significant effect on affinity and the thermodynamics of the binding interaction. To the best of our knowledge, this work is the first to explore the role of Mg2+ in modifying the Ca2+ affinity of cTnC mutations linked to HCM. Our results indicate a physiologically significant role for cellular Mg2+ both at baseline and when elevated on modifying the Ca2+ binding properties of cTnC and the subsequent conformational changes which precede cardiac contraction.
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Affiliation(s)
- Kaveh Rayani
- Molecular Cardiac Physiology Group, Simon Fraser University, Burnaby, Canada
| | - Eric R Hantz
- Department of Chemistry and Biochemistry, Ohio State University, Columbus, OH, USA
| | - Omid Haji-Ghassemi
- Department of Biochemistry and Molecular Biology, The University of British Columbia, Vancouver, Canada
| | - Alison Y Li
- Molecular Cardiac Physiology Group, Simon Fraser University, Burnaby, Canada
| | - Anne M Spuches
- Department of Chemistry, 300 Science and Technology, East Carolina University, Greenville, NC, USA
| | - Filip Van Petegem
- Department of Biochemistry and Molecular Biology, The University of British Columbia, Vancouver, Canada
| | - R John Solaro
- Department of Physiology and Biophysics and the Center for Cardiovascular Research, College of Medicine, University of Illinois at Chicago, USA
| | - Steffen Lindert
- Department of Chemistry and Biochemistry, Ohio State University, Columbus, OH, USA
| | - Glen F Tibbits
- Molecular Cardiac Physiology Group, Simon Fraser University, Burnaby, Canada
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, Canada
- BC Children's Hospital Research Institute, Vancouver, Canada
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8
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Singh RR, Slater RE, Wang J, Wang C, Guo Q, Motani AS, Hartman JJ, Sadayappan S, Ason BL. Distinct Mechanisms for Increased Cardiac Contraction Through Selective Alteration of Either Myosin or Troponin Activity. JACC Basic Transl Sci 2022; 7:1021-1037. [DOI: 10.1016/j.jacbts.2022.04.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Revised: 04/15/2022] [Accepted: 04/18/2022] [Indexed: 10/14/2022]
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9
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Ono S, Lewis M, Ono K. Mutual dependence between tropomodulin and tropomyosin in the regulation of sarcomeric actin assembly in Caenorhabditis elegans striated muscle. Eur J Cell Biol 2022; 101:151215. [PMID: 35306452 PMCID: PMC9081161 DOI: 10.1016/j.ejcb.2022.151215] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Revised: 02/24/2022] [Accepted: 03/14/2022] [Indexed: 11/25/2022] Open
Abstract
Tropomodulin and tropomyosin are important components of sarcomeric thin filaments in striated muscles. Tropomyosin decorates the side of actin filaments and enhances tropomodulin capping at the pointed ends of the filaments. Their functional relationship has been extensively characterized in vitro, but in vivo and cellular studies in mammals are often complicated by the presence of functionally redundant isoforms. Here, we used the nematode Caenorhabditis elegans, which has a relatively simple composition of tropomodulin and tropomyosin genes, and demonstrated that tropomodulin (unc-94) and tropomyosin (lev-11) are mutually dependent on each other in their sarcomere localization and regulation of sarcomeric actin assembly. Mutation of tropomodulin caused sarcomere disorganization with formation of actin aggregates. However, the actin aggregation was suppressed when tropomyosin was depleted in the tropomodulin mutant. Tropomyosin was mislocalized to the actin aggregates in the tropomodulin mutants, while sarcomere localization of tropomodulin was lost when tropomyosin was depleted. These results indicate that tropomodulin and tropomyosin are interdependent in the regulation of organized sarcomeric assembly of actin filaments in vivo.
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Affiliation(s)
- Shoichiro Ono
- Departments of Pathology and Cell Biology, Emory University School of Medicine, Atlanta, GA, USA; Winship Cancer Institute, Emory University School of Medicine, Atlanta, GA, USA.
| | - Mario Lewis
- Departments of Pathology and Cell Biology, Emory University School of Medicine, Atlanta, GA, USA; Winship Cancer Institute, Emory University School of Medicine, Atlanta, GA, USA
| | - Kanako Ono
- Departments of Pathology and Cell Biology, Emory University School of Medicine, Atlanta, GA, USA; Winship Cancer Institute, Emory University School of Medicine, Atlanta, GA, USA
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10
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Frameshift mutation S368fs in the gene encoding cytoskeletal β-actin leads to ACTB-associated syndromic thrombocytopenia by impairing actin dynamics. Eur J Cell Biol 2022; 101:151216. [DOI: 10.1016/j.ejcb.2022.151216] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Revised: 03/13/2022] [Accepted: 03/14/2022] [Indexed: 11/24/2022] Open
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11
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Chen YJ, Chien CS, Chiang CE, Chen CH, Cheng HM. From Genetic Mutations to Molecular Basis of Heart Failure Treatment: An Overview of the Mechanism and Implication of the Novel Modulators for Cardiac Myosin. Int J Mol Sci 2021; 22:6617. [PMID: 34205587 PMCID: PMC8234187 DOI: 10.3390/ijms22126617] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2021] [Revised: 06/11/2021] [Accepted: 06/17/2021] [Indexed: 02/06/2023] Open
Abstract
Heart failure (HF) is a syndrome encompassing several important etiologies that lead to the imbalance between oxygen demand and supply. Despite the usage of guideline-directed medical therapy for HF has shown better outcomes, novel therapeutic strategies are desirable, especially for patients with preserved or mildly reduced left ventricular ejection fraction. In this regard, understanding the molecular basis for cardiomyopathies is expected to fill in the knowledge gap and generate new therapies to improve prognosis for HF. This review discusses an evolutionary mechanism designed to regulate cardiac contraction and relaxation through the most often genetically determined cardiomyopathies associated with HF. In addition, both the myosin inhibitor and myosin activator are promising new treatments for cardiomyopathies. A comprehensive review from genetic mutations to the molecular basis of direct sarcomere modulators will help shed light on future studies for a better characterization of HF etiologies and potential therapeutic targets.
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Affiliation(s)
- Yu-Jen Chen
- Department of Internal Medicine, Division of Cardiovascular Medicine, Wan Fang Hospital, Taipei Medical University, Taipei 116081, Taiwan;
- Department of Internal Medicine, Division of Cardiology, School of Medicine, College of Medicine, Taipei Medical University, Taipei 110301, Taiwan
- Institute of Public Health, National Yang Ming Chiao Tung University, Taipei 112304, Taiwan
| | - Chian-Shiu Chien
- Innovative Cellular Therapy Center, Department of Medical Research, Taipei Veterans General Hospital, Taipei 112201, Taiwan;
| | - Chern-En Chiang
- General Clinical Research Center, Taipei Veterans General Hospital, Taipei 112201, Taiwan;
- Department of Medicine, National Yang Ming Chiao Tung University College of Medicine, Taipei 112304, Taiwan
| | - Chen-Huan Chen
- Department of Medical Education, Taipei Veterans General Hospital, Taipei 112201, Taiwan;
- College of Medicine, National Yang Ming Chiao Tung University, Taipei 112201, Taiwan
| | - Hao-Min Cheng
- Institute of Public Health, National Yang Ming Chiao Tung University, Taipei 112304, Taiwan
- Department of Medicine, National Yang Ming Chiao Tung University College of Medicine, Taipei 112304, Taiwan
- Center for Evidence-Based Medicine, Taipei Veterans General Hospital, Taipei 112201, Taiwan
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12
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Racca AW, Rynkiewicz MJ, LaFave N, Ghosh A, Lehman W, Moore JR. M8R tropomyosin mutation disrupts actin binding and filament regulation: The beginning affects the middle and end. J Biol Chem 2020; 295:17128-17137. [PMID: 33020181 PMCID: PMC7863880 DOI: 10.1074/jbc.ra120.014713] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Revised: 09/28/2020] [Indexed: 11/06/2022] Open
Abstract
Dilated cardiomyopathy (DCM) is associated with mutations in cardiomyocyte sarcomeric proteins, including α-tropomyosin. In conjunction with troponin, tropomyosin shifts to regulate actomyosin interactions. Tropomyosin molecules overlap via tropomyosin-tropomyosin head-to-tail associations, forming a continuous strand along the thin filament. These associations are critical for propagation of tropomyosin's reconfiguration along the thin filament and key for the cooperative switching between heart muscle contraction and relaxation. Here, we tested perturbations in tropomyosin structure, biochemistry, and function caused by the DCM-linked mutation, M8R, which is located at the overlap junction. Localized and nonlocalized structural effects of the mutation were found in tropomyosin that ultimately perturb its thin filament regulatory function. Comparison of mutant and WT α-tropomyosin was carried out using in vitro motility assays, CD, actin co-sedimentation, and molecular dynamics simulations. Regulated thin filament velocity measurements showed that the presence of M8R tropomyosin decreased calcium sensitivity and thin filament cooperativity. The co-sedimentation of actin and tropomyosin showed weakening of actin-mutant tropomyosin binding. The binding of troponin T's N terminus to the actin-mutant tropomyosin complex was also weakened. CD and molecular dynamics indicate that the M8R mutation disrupts the four-helix bundle at the head-to-tail junction, leading to weaker tropomyosin-tropomyosin binding and weaker tropomyosin-actin binding. Molecular dynamics revealed that altered end-to-end bond formation has effects extending toward the central region of the tropomyosin molecule, which alter the azimuthal position of tropomyosin, likely disrupting the mutant thin filament response to calcium. These results demonstrate that mutation-induced alterations in tropomyosin-thin filament interactions underlie the altered regulatory phenotype and ultimately the pathogenesis of DCM.
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Affiliation(s)
- Alice Ward Racca
- Department of Biological Sciences, University of Massachusetts-Lowell, Lowell, Massachusetts, USA
| | - Michael J Rynkiewicz
- Department of Physiology & Biophysics, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Nicholas LaFave
- Department of Biological Sciences, University of Massachusetts-Lowell, Lowell, Massachusetts, USA
| | - Anita Ghosh
- Department of Physiology & Biophysics, Boston University School of Medicine, Boston, Massachusetts, USA
| | - William Lehman
- Department of Physiology & Biophysics, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Jeffrey R Moore
- Department of Biological Sciences, University of Massachusetts-Lowell, Lowell, Massachusetts, USA.
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13
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Powers JD, Kooiker KB, Mason AB, Teitgen AE, Flint GV, Tardiff JC, Schwartz SD, McCulloch AD, Regnier M, Davis J, Moussavi-Harami F. Modulating the tension-time integral of the cardiac twitch prevents dilated cardiomyopathy in murine hearts. JCI Insight 2020; 5:142446. [PMID: 32931484 PMCID: PMC7605524 DOI: 10.1172/jci.insight.142446] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Accepted: 09/09/2020] [Indexed: 12/13/2022] Open
Abstract
Dilated cardiomyopathy (DCM) is often associated with sarcomere protein mutations that confer reduced myofilament tension–generating capacity. We demonstrated that cardiac twitch tension-time integrals can be targeted and tuned to prevent DCM remodeling in hearts with contractile dysfunction. We employed a transgenic murine model of DCM caused by the D230N-tropomyosin (Tm) mutation and designed a sarcomere-based intervention specifically targeting the twitch tension-time integral of D230N-Tm hearts using multiscale computational models of intramolecular and intermolecular interactions in the thin filament and cell-level contractile simulations. Our models predicted that increasing the calcium sensitivity of thin filament activation using the cardiac troponin C (cTnC) variant L48Q can sufficiently augment twitch tension-time integrals of D230N-Tm hearts. Indeed, cardiac muscle isolated from double-transgenic hearts expressing D230N-Tm and L48Q cTnC had increased calcium sensitivity of tension development and increased twitch tension-time integrals compared with preparations from hearts with D230N-Tm alone. Longitudinal echocardiographic measurements revealed that DTG hearts retained normal cardiac morphology and function, whereas D230N-Tm hearts developed progressive DCM. We present a computational and experimental framework for targeting molecular mechanisms governing the twitch tension of cardiomyopathic hearts to counteract putative mechanical drivers of adverse remodeling and open possibilities for tension-based treatments of genetic cardiomyopathies. Tuning the molecular mechanisms that govern the twitch tension of cardiomyopathic hearts counteracts mechanical drivers of adverse remodeling.
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Affiliation(s)
- Joseph D Powers
- Department of Bioengineering, College of Engineering and School of Medicine, University of Washington, Seattle, Washington, USA.,Department of Bioengineering, Jacobs School of Engineering, University of California San Diego, La Jolla, California, USA
| | - Kristina B Kooiker
- Division of Cardiology, School of Medicine, University of Washington, Seattle, Washington, USA
| | - Allison B Mason
- Department of Chemistry and Biochemistry, College of Science, and
| | - Abigail E Teitgen
- Department of Bioengineering, Jacobs School of Engineering, University of California San Diego, La Jolla, California, USA
| | - Galina V Flint
- Department of Bioengineering, College of Engineering and School of Medicine, University of Washington, Seattle, Washington, USA
| | - Jil C Tardiff
- Department of Biomedical Engineering, College of Engineering, University of Arizona, Tucson, Arizona, USA
| | | | - Andrew D McCulloch
- Department of Bioengineering, Jacobs School of Engineering, University of California San Diego, La Jolla, California, USA.,Department of Medicine, University of California San Diego, La Jolla, California, USA
| | - Michael Regnier
- Department of Bioengineering, College of Engineering and School of Medicine, University of Washington, Seattle, Washington, USA
| | - Jennifer Davis
- Department of Bioengineering, College of Engineering and School of Medicine, University of Washington, Seattle, Washington, USA.,Department of Laboratory Medicine & Pathology, University of Washington, Seattle, Washington, USA
| | - Farid Moussavi-Harami
- Division of Cardiology, School of Medicine, University of Washington, Seattle, Washington, USA
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14
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Characterization of arterial flow mediated dilation via a physics-based model. J Mech Behav Biomed Mater 2020; 107:103756. [DOI: 10.1016/j.jmbbm.2020.103756] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2020] [Revised: 03/26/2020] [Accepted: 03/28/2020] [Indexed: 02/06/2023]
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15
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Parker F, Baboolal TG, Peckham M. Actin Mutations and Their Role in Disease. Int J Mol Sci 2020; 21:ijms21093371. [PMID: 32397632 PMCID: PMC7247010 DOI: 10.3390/ijms21093371] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Revised: 05/06/2020] [Accepted: 05/07/2020] [Indexed: 12/15/2022] Open
Abstract
Actin is a widely expressed protein found in almost all eukaryotic cells. In humans, there are six different genes, which encode specific actin isoforms. Disease-causing mutations have been described for each of these, most of which are missense. Analysis of the position of the resulting mutated residues in the protein reveals mutational hotspots. Many of these occur in regions important for actin polymerization. We briefly discuss the challenges in characterizing the effects of these actin mutations, with a focus on cardiac actin mutations.
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16
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Law ML, Cohen H, Martin AA, Angulski ABB, Metzger JM. Dysregulation of Calcium Handling in Duchenne Muscular Dystrophy-Associated Dilated Cardiomyopathy: Mechanisms and Experimental Therapeutic Strategies. J Clin Med 2020; 9:jcm9020520. [PMID: 32075145 PMCID: PMC7074327 DOI: 10.3390/jcm9020520] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Accepted: 02/06/2020] [Indexed: 02/07/2023] Open
Abstract
: Duchenne muscular dystrophy (DMD) is an X-linked recessive disease resulting in the loss of dystrophin, a key cytoskeletal protein in the dystrophin-glycoprotein complex. Dystrophin connects the extracellular matrix with the cytoskeleton and stabilizes the sarcolemma. Cardiomyopathy is prominent in adolescents and young adults with DMD, manifesting as dilated cardiomyopathy (DCM) in the later stages of disease. Sarcolemmal instability, leading to calcium mishandling and overload in the cardiac myocyte, is a key mechanistic contributor to muscle cell death, fibrosis, and diminished cardiac contractile function in DMD patients. Current therapies for DMD cardiomyopathy can slow disease progression, but they do not directly target aberrant calcium handling and calcium overload. Experimental therapeutic targets that address calcium mishandling and overload include membrane stabilization, inhibition of stretch-activated channels, ryanodine receptor stabilization, and augmentation of calcium cycling via modulation of the Serca2a/phospholamban (PLN) complex or cytosolic calcium buffering. This paper addresses what is known about the mechanistic basis of calcium mishandling in DCM, with a focus on DMD cardiomyopathy. Additionally, we discuss currently utilized therapies for DMD cardiomyopathy, and review experimental therapeutic strategies targeting the calcium handling defects in DCM and DMD cardiomyopathy.
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Affiliation(s)
- Michelle L. Law
- Department of Family and Consumer Sciences, Robbins College of Health and Human Sciences, Baylor University, Waco, TX 76706, USA;
| | - Houda Cohen
- Department of Integrative Biology and Physiology, University of Minnesota Medical School, Minneapolis, MN 55455, USA; (H.C.); (A.A.M.); (A.B.B.A.)
| | - Ashley A. Martin
- Department of Integrative Biology and Physiology, University of Minnesota Medical School, Minneapolis, MN 55455, USA; (H.C.); (A.A.M.); (A.B.B.A.)
| | - Addeli Bez Batti Angulski
- Department of Integrative Biology and Physiology, University of Minnesota Medical School, Minneapolis, MN 55455, USA; (H.C.); (A.A.M.); (A.B.B.A.)
| | - Joseph M. Metzger
- Department of Integrative Biology and Physiology, University of Minnesota Medical School, Minneapolis, MN 55455, USA; (H.C.); (A.A.M.); (A.B.B.A.)
- Correspondence: ; Tel.: +1-612-625-5902; Fax: +1-612-625-5149
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17
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Abstract
The cardiac troponin complex, composed of three regulatory proteins (cTnI, cTnT, TnC), functions as the critical regulator of cardiac muscle contraction and relaxation. Myofilament protein-protein interactions are regulated by post-translational modifications (PTMs) to the protein constituents of this complex. Dysregulation of troponin PTMs, particularly phosphorylation, results in altered cardiac contractility. Altered PTMs and isoforms have been increasingly recognized as the molecular mechanisms underlying heart diseases. Therefore, it is essential to comprehensively analyze cardiac troponin proteoforms that arise from PTMs, alternative splicing, and sequence variations. In this chapter, we described two detailed protocols for the enrichment and purification of endogenous cardiac troponin proteoforms from cardiac tissue. Subsequently, mass spectrometry (MS)-based top-down proteomics utilizing online liquid chromatography (LC)/quadrupole time-of-flight (Q-TOF) MS for separation, profiling, and quantification of the troponins was demonstrated. Characterization of troponin amino acid sequence and the localization of PTMs were shown using Fourier-transform ion cyclotron resonance (FT-ICR) MS with electron capture dissociation (ECD) and collisionally activated dissociation (CAD). Furthermore, we described the use of MASH software, a comprehensive and free software package developed in our lab, for top-down proteomics data analysis. The methods we described can be applied for the analysis of troponin proteoforms in cardiac tissues, from animal models to human clinical samples, for heart disease.
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18
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Kagemoto T, Oyama K, Yamane M, Tsukamoto S, Kobirumaki-Shimozawa F, Li A, Dos Remedios C, Fukuda N, Ishiwata S. Sarcomeric Auto-Oscillations in Single Myofibrils From the Heart of Patients With Dilated Cardiomyopathy. Circ Heart Fail 2019; 11:e004333. [PMID: 29980594 DOI: 10.1161/circheartfailure.117.004333] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Accepted: 05/31/2018] [Indexed: 01/30/2023]
Abstract
BACKGROUND Left ventricular wall motion is depressed in patients with dilated cardiomyopathy (DCM). However, whether or not the depressed left ventricular wall motion is caused by impairment of sarcomere dynamics remains to be fully clarified. METHODS AND RESULTS We analyzed the mechanical properties of single sarcomere dynamics during sarcomeric auto-oscillations (calcium spontaneous oscillatory contractions [Ca-SPOC]) that occurred at partial activation under the isometric condition in myofibrils from donor hearts and from patients with severe DCM (New York Heart Association classification III-IV). Ca-SPOC reproducibly occurred in the presence of 1 μmol/L free Ca2+ in both nonfailing and DCM myofibrils, and sarcomeres exhibited a saw-tooth waveform along single myofibrils composed of quick lengthening and slow shortening. The period of Ca-SPOC was longer in DCM myofibrils than in nonfailing myofibrils, in association with prolonged shortening time. Lengthening time was similar in both groups. Then, we performed Tn (troponin) exchange in myofibrils with a DCM-causing homozygous mutation (K36Q) in cTnI (cardiac TnI). On exchange with the Tn complex from healthy porcine ventricles, period, shortening time, and shortening velocity in cTnI-K36Q myofibrils became similar to those in Tn-reconstituted nonfailing myofibrils. Protein kinase A abbreviated period in both Tn-reconstituted nonfailing and cTnI-K36Q myofibrils, demonstrating acceleration of cross-bridge kinetics. CONCLUSIONS Sarcomere dynamics was found to be depressed under loaded conditions in DCM myofibrils because of impairment of thick-thin filament sliding. Thus, microscopic analysis of Ca-SPOC in human cardiac myofibrils is beneficial to systematically unveil the kinetic properties of single sarcomeres in various types of heart disease.
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Affiliation(s)
- Tatsuya Kagemoto
- Department of Physics, Faculty of Science and Engineering, Waseda University, Tokyo, Japan (T.K., M.Y., S.I.)
| | - Kotaro Oyama
- Department of Cell Physiology, The Jikei University School of Medicine, Tokyo, Japan (K.O., S.T., F.K.-S., N.F.)
| | - Mitsunori Yamane
- Department of Physics, Faculty of Science and Engineering, Waseda University, Tokyo, Japan (T.K., M.Y., S.I.)
| | - Seiichi Tsukamoto
- Department of Cell Physiology, The Jikei University School of Medicine, Tokyo, Japan (K.O., S.T., F.K.-S., N.F.)
| | - Fuyu Kobirumaki-Shimozawa
- Department of Cell Physiology, The Jikei University School of Medicine, Tokyo, Japan (K.O., S.T., F.K.-S., N.F.)
| | - Amy Li
- School of Medical Sciences, Bosch Institute, The University of Sydney, Australia (A.L., C.D.R.)
| | - Cristobal Dos Remedios
- School of Medical Sciences, Bosch Institute, The University of Sydney, Australia (A.L., C.D.R.)
| | - Norio Fukuda
- Department of Cell Physiology, The Jikei University School of Medicine, Tokyo, Japan (K.O., S.T., F.K.-S., N.F.).
| | - Shin'ichi Ishiwata
- Department of Physics, Faculty of Science and Engineering, Waseda University, Tokyo, Japan (T.K., M.Y., S.I.).
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19
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Marston S. Small molecule studies: the fourth wave of muscle research. J Muscle Res Cell Motil 2019; 40:69-76. [PMID: 31228047 PMCID: PMC6726831 DOI: 10.1007/s10974-019-09526-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Accepted: 06/13/2019] [Indexed: 12/28/2022]
Abstract
The study of muscle and contractility is an unusual scientific endeavour since it has from the start been focussed on one problem-What makes muscle work?-and yet has needed a vast range of different approaches and techniques to study it. Its uniqueness lies in the fundamental fascination of a large scale molecular machine that converts chemical energy into mechanical energy at ambient temperature and with high efficiency that is also controlled by an exquisitely intricate yet utterly reliable regulatory system and is an essential component of animal life. The investigation of muscle is as innovative as any other field of research. As soon as one approach appears to be played out another comes along. It is instructive to consider this as a series of waves of novel and heightened activity starting in the 1950s. The thesis of this article is that we are approaching the fourth wave with the recent rise of interest in small molecules as research tools and possible therapies for muscle diseases.
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Affiliation(s)
- Steven Marston
- Cardiovascular Division, National Heart and Lung Institute, Imperial Centre for Translational and Experimental Medicine, Imperial College London, Hammersmith Campus, Du Cane Road, London, W12 0NN, UK.
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20
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Yoshihisa A, Kiko T, Sato T, Oikawa M, Kobayashi A, Takeishi Y. Urinary N-terminal fragment of titin is a marker to diagnose muscular dystrophy in patients with cardiomyopathy. Clin Chim Acta 2018; 484:226-230. [DOI: 10.1016/j.cca.2018.06.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2018] [Revised: 05/30/2018] [Accepted: 06/01/2018] [Indexed: 12/22/2022]
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21
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The Molecular Mechanisms of Mutations in Actin and Myosin that Cause Inherited Myopathy. Int J Mol Sci 2018; 19:ijms19072020. [PMID: 29997361 PMCID: PMC6073311 DOI: 10.3390/ijms19072020] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2018] [Revised: 07/06/2018] [Accepted: 07/08/2018] [Indexed: 12/23/2022] Open
Abstract
The discovery that mutations in myosin and actin genes, together with mutations in the other components of the muscle sarcomere, are responsible for a range of inherited muscle diseases (myopathies) has revolutionized the study of muscle, converting it from a subject of basic science to a relevant subject for clinical study and has been responsible for a great increase of interest in muscle studies. Myopathies are linked to mutations in five of the myosin heavy chain genes, three of the myosin light chain genes, and three of the actin genes. This review aims to determine to what extent we can explain disease phenotype from the mutant genotype. To optimise our chances of finding the right mechanism we must study a myopathy where there are a large number of different mutations that cause a common phenotype and so are likely to have a common mechanism: a corollary to this criterion is that if any mutation causes the disease phenotype but does not correspond to the proposed mechanism, then the whole mechanism is suspect. Using these criteria, we consider two cases where plausible genotype-phenotype mechanisms have been proposed: the actin “A-triad” and the myosin “mesa/IHD” models.
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Ujfalusi Z, Vera CD, Mijailovich SM, Svicevic M, Yu EC, Kawana M, Ruppel KM, Spudich JA, Geeves MA, Leinwand LA. Dilated cardiomyopathy myosin mutants have reduced force-generating capacity. J Biol Chem 2018; 293:9017-9029. [PMID: 29666183 PMCID: PMC5995530 DOI: 10.1074/jbc.ra118.001938] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Revised: 04/14/2018] [Indexed: 11/06/2022] Open
Abstract
Dilated cardiomyopathy (DCM) and hypertrophic cardiomyopathy (HCM) can cause arrhythmias, heart failure, and cardiac death. Here, we functionally characterized the motor domains of five DCM-causing mutations in human β-cardiac myosin. Kinetic analyses of the individual events in the ATPase cycle revealed that each mutation alters different steps in this cycle. For example, different mutations gave enhanced or reduced rate constants of ATP binding, ATP hydrolysis, or ADP release or exhibited altered ATP, ADP, or actin affinity. Local effects dominated, no common pattern accounted for the similar mutant phenotype, and there was no distinct set of changes that distinguished DCM mutations from previously analyzed HCM myosin mutations. That said, using our data to model the complete ATPase contraction cycle revealed additional critical insights. Four of the DCM mutations lowered the duty ratio (the ATPase cycle portion when myosin strongly binds actin) because of reduced occupancy of the force-holding A·M·D complex in the steady state. Under load, the A·M·D state is predicted to increase owing to a reduced rate constant for ADP release, and this effect was blunted for all five DCM mutations. We observed the opposite effects for two HCM mutations, namely R403Q and R453C. Moreover, the analysis predicted more economical use of ATP by the DCM mutants than by WT and the HCM mutants. Our findings indicate that DCM mutants have a deficit in force generation and force-holding capacity due to the reduced occupancy of the force-holding state.
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Affiliation(s)
- Zoltan Ujfalusi
- From the School of Biosciences, University of Kent, Canterbury CT2 7NJ, United Kingdom
- the Department of Biophysics, University of Pécs, Medical School, Szigeti Street 12, H-7624 Pécs, Hungary
| | - Carlos D Vera
- the BioFrontiers Institute and Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, Colorado 80309
| | | | - Marina Svicevic
- the Faculty of Science, University of Kragujevac, Kragujevac 34000, Serbia
| | | | - Masataka Kawana
- Biochemistry, Stanford University School of Medicine, Stanford, California 94305, and
| | - Kathleen M Ruppel
- Biochemistry, Stanford University School of Medicine, Stanford, California 94305, and
| | - James A Spudich
- Biochemistry, Stanford University School of Medicine, Stanford, California 94305, and
| | - Michael A Geeves
- From the School of Biosciences, University of Kent, Canterbury CT2 7NJ, United Kingdom,
| | - Leslie A Leinwand
- the BioFrontiers Institute and Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, Colorado 80309,
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Abstract
Titin is associated with myocardial stiffness and hypertrophy, and mutations in its gene have been identified in cardiac myopathies such as dilated cardiomyopathy (DC). It has recently been reported that in damaged muscle, the N-terminal fragment of titin (Titin-N) is cleaved by calpain-3, and urinary Titin-N (U-TN) could be a marker of sarcomere damage. We aimed to investigate the impact of U-TN on prognosis of DC. We measured urinary levels of Titin-N/creatinine ratio (U-TN/Cr; pmol/mg/dl) in 102 patients with DC, and followed up all the patients (mean 1,167 days). The patients were divided into 3 groups based on the U-TN/Cr: first (U-TN/Cr <3.35, n = 34), second (3.35 ≤ U-TN/Cr <7.26, n = 34), and third (7.26 ≤ U-TN/Cr, n = 34) tertiles. In the Kaplan-Meier analysis, cardiac and all-cause mortality progressively increased from the first to the second and third groups (p <0.05, respectively). In the Cox proportional hazard analyses, U-TN/Cr was a predictor of cardiac and all-cause mortality in patients with DC (p <0.05, respectively). U-TN, a possible marker of sarcomere damage, can identify high-risk patients with DC.
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Farman GP, Rynkiewicz MJ, Orzechowski M, Lehman W, Moore JR. HCM and DCM cardiomyopathy-linked α-tropomyosin mutations influence off-state stability and crossbridge interaction on thin filaments. Arch Biochem Biophys 2018; 647:84-92. [PMID: 29626422 DOI: 10.1016/j.abb.2018.04.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Revised: 04/02/2018] [Accepted: 04/03/2018] [Indexed: 12/19/2022]
Abstract
Calcium regulation of cardiac muscle contraction is controlled by the thin-filament proteins troponin and tropomyosin bound to actin. In the absence of calcium, troponin-tropomyosin inhibits myosin-interactions on actin and induces muscle relaxation, whereas the addition of calcium relieves the inhibitory constraint to initiate contraction. Many mutations in thin filament proteins linked to cardiomyopathy appear to disrupt this regulatory switching. Here, we tested perturbations caused by mutant tropomyosins (E40K, DCM; and E62Q, HCM) on intra-filament interactions affecting acto-myosin interactions including those induced further by myosin association. Comparison of wild-type and mutant human α-tropomyosin (Tpm1.1) behavior was carried out using in vitro motility assays and molecular dynamics simulations. Our results show that E62Q tropomyosin destabilizes thin filament off-state function by increasing calcium-sensitivity, but without apparent affect on global tropomyosin structure by modifying coiled-coil rigidity. In contrast, the E40K mutant tropomyosin appears to stabilize the off-state, demonstrates increased tropomyosin flexibility, while also decreasing calcium-sensitivity. In addition, the E40K mutation reduces thin filament velocity at low myosin concentration while the E62Q mutant tropomyosin increases velocity. Corresponding molecular dynamics simulations indicate specific residue interactions that are likely to redefine underlying molecular regulatory mechanisms, which we propose explain the altered contractility evoked by the disease-causing mutations.
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Affiliation(s)
- Gerrie P Farman
- Department of Biological Sciences, University of Massachusetts-Lowell, One University Avenue, Lowell, MA 01854, USA; Department of Physiology & Biophysics, Boston University School of Medicine, 700 Albany Street, Boston, MA 02118, USA.
| | - Michael J Rynkiewicz
- Department of Physiology & Biophysics, Boston University School of Medicine, 700 Albany Street, Boston, MA 02118, USA.
| | - Marek Orzechowski
- Department of Physiology & Biophysics, Boston University School of Medicine, 700 Albany Street, Boston, MA 02118, USA.
| | - William Lehman
- Department of Physiology & Biophysics, Boston University School of Medicine, 700 Albany Street, Boston, MA 02118, USA.
| | - Jeffrey R Moore
- Department of Biological Sciences, University of Massachusetts-Lowell, One University Avenue, Lowell, MA 01854, USA.
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Mahdieh N, Hosseini Moghaddam M, Motavaf M, Rabbani A, Soveizi M, Maleki M, Rabbani B, Alizadeh-Asl A. Genotypic effect of a mutation of the MYBPC3 gene and two phenotypes with different patterns of inheritance. J Clin Lab Anal 2018; 32:e22419. [PMID: 29493010 DOI: 10.1002/jcla.22419] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Accepted: 02/03/2018] [Indexed: 01/05/2023] Open
Abstract
BACKGROUND MYBPC3 mutations have been described in dilated cardiomyopathy (DCM) and hypertrophic cardiomyopathy (HCM). A mutation, c.3373G>A, has been reported to cause autosomal recessive form of HCM. Here, we report that this mutation can cause autosomal dominant form of DCM. METHODS Next-generation sequencing using targeted panel of a total of 23 candidate genes and following Sanger sequencing was applied to detect causal mutations of DCM. Computational analyses were also performed using available software tools. In silico structural and functional analyses including protein modeling and prediction were done for the mutated MYBPC3 protein. RESULTS AND CONCLUSION Targeted sequencing showed one variant c.3373G>A (p.Val1125Met) in the studied family following autosomal dominant inheritance. Computational programs predicted a high score of pathogenicity. Secondary structure of the region surrounding p.Val1125 was changed to a shortened beta-strand based on prediction of I-TASSER and Phyre2 servers with high confidence value for the mutation. cMyBP-C protein was modeled to 3dmkA. Our findings suggest that one single mutation of MYBPC3 may have different effects on the cellular mechanisms based of its zygosity. Various factors might be considered for explaining this phenomenon. This gene may have an important role in Iranian DCM and HCM patients.
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Affiliation(s)
- Nejat Mahdieh
- Cardiogenetics Research Laboratory, Rajaie Cardiovascular Medical and Research Center, Iran University of Medical Sciences, Tehran, Iran
| | - Maryam Hosseini Moghaddam
- Cardiogenetics Research Laboratory, Rajaie Cardiovascular Medical and Research Center, Iran University of Medical Sciences, Tehran, Iran
| | - Mahsa Motavaf
- Faculty of Biological Science, Department of Molecular Genetics, Tarbiat Modares University, Tehran, Iran
| | - Ahmad Rabbani
- Rajaie Cardiovascular Medical and Research Center, Iran University of Medical Sciences, Tehran, Iran
| | - Mahdieh Soveizi
- Cardiogenetics Research Laboratory, Rajaie Cardiovascular Medical and Research Center, Iran University of Medical Sciences, Tehran, Iran
| | - Majid Maleki
- Rajaie Cardiovascular Medical and Research Center, Iran University of Medical Sciences, Tehran, Iran
| | - Bahareh Rabbani
- Cardiogenetics Research Laboratory, Rajaie Cardiovascular Medical and Research Center, Iran University of Medical Sciences, Tehran, Iran
| | - Azin Alizadeh-Asl
- Rajaie Cardiovascular Medical and Research Center, Iran University of Medical Sciences, Tehran, Iran
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Dewan S, McCabe KJ, Regnier M, McCulloch AD. Insights and Challenges of Multi-Scale Modeling of Sarcomere Mechanics in cTn and Tm DCM Mutants-Genotype to Cellular Phenotype. Front Physiol 2017; 8:151. [PMID: 28352236 PMCID: PMC5348544 DOI: 10.3389/fphys.2017.00151] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2016] [Accepted: 02/24/2017] [Indexed: 01/18/2023] Open
Abstract
Dilated Cardiomyopathy (DCM) is a leading cause of sudden cardiac death characterized by impaired pump function and dilatation of cardiac ventricles. In this review we discuss various in silico approaches to elucidating the mechanisms of genetic mutations leading to DCM. The approaches covered in this review focus on bridging the spatial and temporal gaps that exist between molecular and cellular processes. Mutations in sarcomeric regulatory thin filament proteins such as the troponin complex (cTn) and Tropomyosin (Tm) have been associated with DCM. Despite the experimentally-observed myofilament measures of contractility in the case of these mutations, the mechanisms by which the underlying molecular changes and protein interactions scale up to organ failure by these mutations remains elusive. The review highlights multi-scale modeling approaches and their applicability to study the effects of sarcomeric gene mutations in-silico. We discuss some of the insights that can be gained from computational models of cardiac biomechanics when scaling from molecular states to cellular level.
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Affiliation(s)
- Sukriti Dewan
- Departments of Bioengineering and Medicine, University of California San Diego, La Jolla, CA, USA
| | - Kimberly J McCabe
- Departments of Bioengineering and Medicine, University of California San Diego, La Jolla, CA, USA
| | - Michael Regnier
- Departments of Bioengineering and Medicine, University of Washington Seattle, WA, USA
| | - Andrew D McCulloch
- Departments of Bioengineering and Medicine, University of California San Diego, La Jolla, CA, USA
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Colak D, Alaiya AA, Kaya N, Muiya NP, AlHarazi O, Shinwari Z, Andres E, Dzimiri N. Integrated Left Ventricular Global Transcriptome and Proteome Profiling in Human End-Stage Dilated Cardiomyopathy. PLoS One 2016; 11:e0162669. [PMID: 27711126 PMCID: PMC5053516 DOI: 10.1371/journal.pone.0162669] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2016] [Accepted: 08/28/2016] [Indexed: 01/30/2023] Open
Abstract
Aims The disease pathways leading to idiopathic dilated cardiomyopathy (DCM) are still elusive. The present study investigated integrated global transcriptional and translational changes in human DCM for disease biomarker discovery. Methods We used identical myocardial tissues from five DCM hearts compared to five non-failing (NF) donor hearts for both transcriptome profiling using the ABI high-density oligonucleotide microarrays and proteome expression with One-Dimensional Nano Acquity liquid chromatography coupled with tandem mass spectrometry on the Synapt G2 system. Results We identified 1262 differentially expressed genes (DEGs) and 269 proteins (DEPs) between DCM cases and healthy controls. Among the most significantly upregulated (>5-fold) proteins were GRK5, APOA2, IGHG3, ANXA6, HSP90AA1, and ATP5C1 (p< 0.01). On the other hand, the most significantly downregulated proteins were GSTM5, COX17, CAV1 and ANXA3. At least ten entities were concomitantly upregulated on the two analysis platforms: GOT1, ALDH4A1, PDHB, BDH1, SLC2A11, HSP90AA1, HSP90AB1, H2AFV, HSPA5 and NDUFV1. Gene ontology analyses of DEGs and DEPs revealed significant overlap with enrichment of genes/proteins related to metabolic process, biosynthetic process, cellular component organization, oxidative phosphorylation, alterations in glycolysis and ATP synthesis, Alzheimer’s disease, chemokine-mediated inflammation and cytokine signalling pathways. Conclusion The concomitant use of transcriptome and proteome expression to evaluate global changes in DCM has led to the identification of sixteen commonly altered entities as well as novel genes, proteins and pathways whose cardiac functions have yet to be deciphered. This data should contribute towards better management of the disease.
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Affiliation(s)
- Dilek Colak
- Biostatistics, Epidemiology and Scientific Computing Department, King Faisal Specialist Hospital and Research Centre, Riyadh, 11211, Saudi Arabia
| | - Ayodele A. Alaiya
- Proteomics Unit, Stem Cell Tissue Re-Engineering Program, King Faisal Specialist Hospital and Research Centre, Riyadh, 11211, Saudi Arabia
| | - Namik Kaya
- Genetics Department, King Faisal Specialist Hospital and Research Centre, Riyadh, 11211, Saudi Arabia
| | - Nzioka P. Muiya
- Genetics Department, King Faisal Specialist Hospital and Research Centre, Riyadh, 11211, Saudi Arabia
| | - Olfat AlHarazi
- Biostatistics, Epidemiology and Scientific Computing Department, King Faisal Specialist Hospital and Research Centre, Riyadh, 11211, Saudi Arabia
| | - Zakia Shinwari
- Proteomics Unit, Stem Cell Tissue Re-Engineering Program, King Faisal Specialist Hospital and Research Centre, Riyadh, 11211, Saudi Arabia
| | - Editha Andres
- Genetics Department, King Faisal Specialist Hospital and Research Centre, Riyadh, 11211, Saudi Arabia
| | - Nduna Dzimiri
- Genetics Department, King Faisal Specialist Hospital and Research Centre, Riyadh, 11211, Saudi Arabia
- * E-mail:
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Ochala J, Sun YB. Novel myosin-based therapies for congenital cardiac and skeletal myopathies. J Med Genet 2016; 53:651-4. [PMID: 27412953 PMCID: PMC5099184 DOI: 10.1136/jmedgenet-2016-103881] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Accepted: 06/15/2016] [Indexed: 12/13/2022]
Abstract
The dysfunction in a number of inherited cardiac and skeletal myopathies is primarily due to an altered ability of myofilaments to generate force and motion. Despite this crucial knowledge, there are, currently, no effective therapeutic interventions for these diseases. In this short review, we discuss recent findings giving strong evidence that genetically or pharmacologically modulating one of the myofilament proteins, myosin, could alleviate the muscle pathology. This should constitute a research and clinical priority.
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Affiliation(s)
- Julien Ochala
- Centre of Human and Aerospace Physiological Sciences, King's College London, London, UK
| | - Yin-Biao Sun
- Randall Division of Cell and Molecular Biophysics, British Heart Foundation Centre of Research Excellence, King's College London, London, UK
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Hussain S, Haroon J, Ejaz S, Javed Q. Variants of resistin gene and the risk of idiopathic dilated cardiomyopathy in Pakistan. Meta Gene 2016; 9:37-41. [PMID: 27114921 PMCID: PMC4833058 DOI: 10.1016/j.mgene.2016.03.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Revised: 02/27/2016] [Accepted: 03/25/2016] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND In cardiovascular disease phenotypes, a genetic factor is an important determinant of both familial and non-familial dilated cardiomyopathies. Resistin is a novel adipocyte derived peptide, associated with inflammation and suggested to be involved in contractile abnormalities of cardiomyocytes. METHODS In this study, we examined the association of the RETN SNPs in - 420 and + 299 in patients with idiopathic dilated cardiomyopathy (IDCM). Patients with IDCM (n = 250) and healthy controls (n = 250) were enrolled in this study. RETN genotyping was performed by using PCR-RFLP method. RESULTS RETN - 420C > G and + 299G > A polymorphisms were significantly more prevalent in patient group vs. controls (P < 0.0001 and P = 0.0007, respectively). GG genotype at - 420 and AA genotype at + 299 were higher in the patient group compared with healthy controls (OR = 11.4, P < 0.0001, and OR = 2.3, P = 0.030, respectively). We found that the - 420G allele increased the risk of developing IDCM in patients (P < 0.0001). Moreover, there was a significant difference between G and A alleles at RETN + 299 from IDCM cases and controls (P = 0.0032). The RETN - 420G and + 299A haplotypes were more prevalent in the patient vs. control group (P < 0.0001). CONCLUSION The results suggest that the RETN - 420C > G and + 299G > A polymorphisms may have a role in the pathogenesis of IDCM.
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Affiliation(s)
- Sabir Hussain
- Department of Biosciences, COMSATS Institute of Information Technology, Islamabad 45550, Pakistan
| | - Javeria Haroon
- Department of Biochemistry, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad 45320, Pakistan
| | - Shagufta Ejaz
- Department of Cardiology, Federal Government Polyclinic Hospital, G-5, Islamabad, Pakistan
| | - Qamar Javed
- Department of Biochemistry, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad 45320, Pakistan
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Taghli-Lamallem O, Plantié E, Jagla K. Drosophila in the Heart of Understanding Cardiac Diseases: Modeling Channelopathies and Cardiomyopathies in the Fruitfly. J Cardiovasc Dev Dis 2016; 3:jcdd3010007. [PMID: 29367558 PMCID: PMC5715700 DOI: 10.3390/jcdd3010007] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2015] [Revised: 01/23/2016] [Accepted: 02/06/2016] [Indexed: 12/16/2022] Open
Abstract
Cardiovascular diseases and, among them, channelopathies and cardiomyopathies are a major cause of death worldwide. The molecular and genetic defects underlying these cardiac disorders are complex, leading to a large range of structural and functional heart phenotypes. Identification of molecular and functional mechanisms disrupted by mutations causing channelopathies and cardiomyopathies is essential to understanding the link between an altered gene and clinical phenotype. The development of animal models has been proven to be efficient for functional studies in channelopathies and cardiomyopathies. In particular, the Drosophila model has been largely applied for deciphering the molecular and cellular pathways affected in these inherited cardiac disorders and for identifying their genetic modifiers. Here we review the utility and the main contributions of the fruitfly models for the better understanding of channelopathies and cardiomyopathies. We also discuss the investigated pathological mechanisms and the discoveries of evolutionarily conserved pathways which reinforce the value of Drosophila in modeling human cardiac diseases.
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Affiliation(s)
- Ouarda Taghli-Lamallem
- GReD (Genetics, Reproduction and Development laboratory), INSERM U1103, CNRS UMR6293, University of Clermont-Ferrand, 28 place Henri-Dunant, 63000 Clermont-Ferrand, France.
| | - Emilie Plantié
- GReD (Genetics, Reproduction and Development laboratory), INSERM U1103, CNRS UMR6293, University of Clermont-Ferrand, 28 place Henri-Dunant, 63000 Clermont-Ferrand, France.
| | - Krzysztof Jagla
- GReD (Genetics, Reproduction and Development laboratory), INSERM U1103, CNRS UMR6293, University of Clermont-Ferrand, 28 place Henri-Dunant, 63000 Clermont-Ferrand, France.
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31
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Wilkinson R, Song W, Smoktunowicz N, Marston S. A dilated cardiomyopathy mutation blunts adrenergic response and induces contractile dysfunction under chronic angiotensin II stress. Am J Physiol Heart Circ Physiol 2015; 309:H1936-46. [PMID: 26432839 DOI: 10.1152/ajpheart.00327.2015] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Accepted: 10/02/2015] [Indexed: 11/22/2022]
Abstract
We investigated cardiac contractility in the ACTC E361G transgenic mouse model of dilated cardiomyopathy (DCM). No differences in cardiac dimensions or systolic function were observed in young mice, whereas young adult mice exhibited only mild diastolic abnormalities. Dobutamine had an inotropic and lusitropic effect on the mouse heart. In papillary muscle at 37°C, dobutamine increased relaxation rates [∼50% increase of peak rate of force decline normalized to force (dF/dtmin/F), 25% reduction of time to 90% relaxation (t90) in nontransgenic (NTG) mice], but in the ACTC E361G mouse, dF/dtmin/F was increased 20-30%, and t90 was only reduced 10% at 10 Hz. Pressure-volume measurements showed increases in maximum rate of pressure decline and decreases in time constant of left ventricular pressure decay in the ACTC E361G mouse that were 25-30% of the changes in the NTG mouse, consistent with blunting of the lusitropic response. The inotropic effect of dobutamine was also blunted in ACTC E361G mice, and the dobutamine-stimulated increase in cardiac output (CO) was reduced from 2,100 to 900 μl/min. Mice were treated with high doses of ANG II for 4 wk. The chronic stress treatment evoked systolic dysfunction in ACTC E361G mice but not in NTG. There was a significant reduction in rates of pressure increase and decrease, as well as reduced end-systolic pressure and increased volume. Ejection fraction and CO were reduced in the ACTC E361G mouse, indicating DCM. In vitro DCM-causing mutations uncouple the relationship between Ca(2+) sensitivity and troponin I phosphorylation. We conclude that this leads to the observed, reduced response to β1 agonists and reduced cardiac reserve that predisposes the heart to DCM under conditions of chronic stress.
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Affiliation(s)
- Ross Wilkinson
- National Heart and Lung Institute, Imperial College London, London, United Kingdom
| | - Weihua Song
- National Heart and Lung Institute, Imperial College London, London, United Kingdom
| | - Natalia Smoktunowicz
- National Heart and Lung Institute, Imperial College London, London, United Kingdom
| | - Steven Marston
- National Heart and Lung Institute, Imperial College London, London, United Kingdom
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McConnell BK, Singh S, Fan Q, Hernandez A, Portillo JP, Reiser PJ, Tikunova SB. Knock-in mice harboring a Ca(2+) desensitizing mutation in cardiac troponin C develop early onset dilated cardiomyopathy. Front Physiol 2015; 6:242. [PMID: 26379556 PMCID: PMC4550777 DOI: 10.3389/fphys.2015.00242] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Accepted: 08/11/2015] [Indexed: 12/05/2022] Open
Abstract
The physiological consequences of aberrant Ca(2+) binding and exchange with cardiac myofilaments are not clearly understood. In order to examine the effect of decreasing Ca(2+) sensitivity of cTnC on cardiac function, we generated knock-in mice carrying a D73N mutation (not known to be associated with heart disease in human patients) in cTnC. The D73N mutation was engineered into the regulatory N-domain of cTnC in order to reduce Ca(2+) sensitivity of reconstituted thin filaments by increasing the rate of Ca(2+) dissociation. In addition, the D73N mutation drastically blunted the extent of Ca(2+) desensitization of reconstituted thin filaments induced by cTnI pseudo-phosphorylation. Compared to wild-type mice, heterozygous knock-in mice carrying the D73N mutation exhibited a substantially decreased Ca(2+) sensitivity of force development in skinned ventricular trabeculae. Kaplan-Meier survival analysis revealed that median survival time for knock-in mice was 12 weeks. Echocardiographic analysis revealed that knock-in mice exhibited increased left ventricular dimensions with thinner walls. Echocardiographic analysis also revealed that measures of systolic function, such as ejection fraction (EF) and fractional shortening (FS), were dramatically reduced in knock-in mice. In addition, knock-in mice displayed electrophysiological abnormalities, namely prolonged QRS and QT intervals. Furthermore, ventricular myocytes isolated from knock-in mice did not respond to β-adrenergic stimulation. Thus, knock-in mice developed pathological features similar to those observed in human patients with dilated cardiomyopathy (DCM). In conclusion, our results suggest that decreasing Ca(2+) sensitivity of the regulatory N-domain of cTnC is sufficient to trigger the development of DCM.
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Affiliation(s)
- Bradley K. McConnell
- Department of Pharmacological and Pharmaceutical Sciences, University of HoustonHouston, TX, USA
| | - Sonal Singh
- Department of Pharmacological and Pharmaceutical Sciences, University of HoustonHouston, TX, USA
| | - Qiying Fan
- Department of Pharmacological and Pharmaceutical Sciences, University of HoustonHouston, TX, USA
| | - Adriana Hernandez
- Department of Pharmacological and Pharmaceutical Sciences, University of HoustonHouston, TX, USA
| | - Jesus P. Portillo
- Department of Pharmacological and Pharmaceutical Sciences, University of HoustonHouston, TX, USA
| | - Peter J. Reiser
- Division of Biosciences, College of Dentistry, The Ohio State UniversityColumbus, OH, USA
| | - Svetlana B. Tikunova
- Department of Pharmacological and Pharmaceutical Sciences, University of HoustonHouston, TX, USA
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Li MX, Hwang PM. Structure and function of cardiac troponin C (TNNC1): Implications for heart failure, cardiomyopathies, and troponin modulating drugs. Gene 2015; 571:153-66. [PMID: 26232335 DOI: 10.1016/j.gene.2015.07.074] [Citation(s) in RCA: 85] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2015] [Revised: 06/24/2015] [Accepted: 07/21/2015] [Indexed: 10/23/2022]
Abstract
In striated muscle, the protein troponin complex turns contraction on and off in a calcium-dependent manner. The calcium-sensing component of the complex is troponin C, which is expressed from the TNNC1 gene in both cardiac muscle and slow-twitch skeletal muscle (identical transcript in both tissues) and the TNNC2 gene in fast-twitch skeletal muscle. Cardiac troponin C (cTnC) is made up of two globular EF-hand domains connected by a flexible linker. The structural C-domain (cCTnC) contains two high affinity calcium-binding sites that are always occupied by Ca(2+) or Mg(2+) under physiologic conditions, stabilizing an open conformation that remains anchored to the rest of the troponin complex. In contrast, the regulatory N-domain (cNTnC) contains a single low affinity site that is largely unoccupied at resting calcium concentrations. During muscle activation, calcium binding to cNTnC favors an open conformation that binds to the switch region of troponin I, removing adjacent inhibitory regions of troponin I from actin and allowing muscle contraction to proceed. Regulation of the calcium binding affinity of cNTnC is physiologically important, because it directly impacts the calcium sensitivity of muscle contraction. Calcium sensitivity can be modified by drugs that stabilize the open form of cNTnC, post-translational modifications like phosphorylation of troponin I, or downstream thin filament protein interactions that impact the availability of the troponin I switch region. Recently, mutations in cTnC have been associated with hypertrophic or dilated cardiomyopathy. A detailed understanding of how calcium sensitivity is regulated through the troponin complex is necessary for explaining how mutations perturb its function to promote cardiomyopathy and how post-translational modifications in the thin filament affect heart function and heart failure. Troponin modulating drugs are being developed for the treatment of cardiomyopathies and heart failure.
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Affiliation(s)
- Monica X Li
- Department of Medicine, University of Alberta, Edmonton, AB T6G 2G3, Canada; Department of Biochemistry, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Peter M Hwang
- Department of Medicine, University of Alberta, Edmonton, AB T6G 2G3, Canada; Department of Biochemistry, University of Alberta, Edmonton, AB T6G 2H7, Canada.
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Kimura A. Molecular genetics and pathogenesis of cardiomyopathy. J Hum Genet 2015; 61:41-50. [PMID: 26178429 DOI: 10.1038/jhg.2015.83] [Citation(s) in RCA: 76] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Accepted: 06/15/2015] [Indexed: 12/19/2022]
Abstract
Cardiomyopathy is defined as a disease of functional impairment in the cardiac muscle and its etiology includes both extrinsic and intrinsic factors. Cardiomyopathy caused by the intrinsic factors is called as primary cardiomyopathy of which two major clinical phenotypes are hypertrophic cardiomyopathy (HCM) and dilated cardiomyopathy (DCM). Genetic approaches have revealed the disease genes for hereditary primary cardiomyopathy and functional studies have demonstrated that characteristic functional alterations induced by the disease-associated mutations are closely related to the clinical types, such that increased and decreased Ca(2+) sensitivities of muscle contraction are associated with HCM and DCM, respectively. In addition, recent studies have suggested that mutations in the Z-disc components found in HCM and DCM may result in increased and decreased stiffness of sarcomere, respectively. Moreover, functional analysis of mutations in the other components of cardiac muscle have suggested that the altered response to metabolic stresses is associated with cardiomyopathy, further indicating the heterogeneity in the etiology and pathogenesis of cardiomyopathy.
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Affiliation(s)
- Akinori Kimura
- Department of Molecular Pathogenesis, Medical Research Institute, Tokyo Medical and Dental University (TMDU), Tokyo, Japan
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Vikhorev PG, Song W, Wilkinson R, Copeland O, Messer AE, Ferenczi MA, Marston SB. The dilated cardiomyopathy-causing mutation ACTC E361G in cardiac muscle myofibrils specifically abolishes modulation of Ca(2+) regulation by phosphorylation of troponin I. Biophys J 2015; 107:2369-80. [PMID: 25418306 PMCID: PMC4241448 DOI: 10.1016/j.bpj.2014.10.024] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2014] [Revised: 09/25/2014] [Accepted: 10/16/2014] [Indexed: 01/30/2023] Open
Abstract
Phosphorylation of troponin I by protein kinase A (PKA) reduces Ca2+ sensitivity and increases the rate of Ca2+ release from troponin C and the rate of relaxation in cardiac muscle. In vitro experiments indicate that mutations that cause dilated cardiomyopathy (DCM) uncouple this modulation, but this has not been demonstrated in an intact contractile system. Using a Ca2+-jump protocol, we measured the effect of the DCM-causing mutation ACTC E361G on the equilibrium and kinetic parameters of Ca2+ regulation of contractility in single transgenic mouse heart myofibrils. We used propranolol treatment of mice to reduce the level of troponin I and myosin binding protein C (MyBP-C) phosphorylation in their hearts before isolating the myofibrils. In nontransgenic mouse myofibrils, the Ca2+ sensitivity of force was increased, the fast relaxation phase rate constant, kREL, was reduced, and the length of the slow linear phase, tLIN, was increased when the troponin I phosphorylation level was reduced from 1.02 to 0.3 molPi/TnI (EC50 P/unP = 1.8 ± 0.2, p < 0.001). Native myofibrils from ACTC E361G transgenic mice had a 2.4-fold higher Ca2+ sensitivity than nontransgenic mouse myofibrils. Strikingly, the Ca2+ sensitivity and relaxation parameters of ACTC E361G myofibrils did not depend on the troponin I phosphorylation level (EC50 P/unP = 0.88 ± 0.17, p = 0.39). Nevertheless, modulation of the Ca2+ sensitivity of ACTC E361G myofibrils by sarcomere length or EMD57033 was indistinguishable from that of nontransgenic myofibrils. Overall, EC50 measured in different conditions varied over a 7-fold range. The time course of relaxation, as defined by tLIN and kREL, was correlated with EC50 but varied by just 2.7- and 3.3-fold, respectively. Our results confirm that troponin I phosphorylation specifically alters the Ca2+ sensitivity of isometric tension and the time course of relaxation in cardiac muscle myofibrils. Moreover, the DCM-causing mutation ACTC E361G blunts this phosphorylation-dependent response without affecting other parameters of contraction, including length-dependent activation and the response to EMD57033.
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Affiliation(s)
- Petr G Vikhorev
- National Heart and Lung Institute, Imperial College London, London, UK
| | - Weihua Song
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore
| | - Ross Wilkinson
- National Heart and Lung Institute, Imperial College London, London, UK
| | - O'Neal Copeland
- National Heart and Lung Institute, Imperial College London, London, UK
| | - Andrew E Messer
- National Heart and Lung Institute, Imperial College London, London, UK
| | - Michael A Ferenczi
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore
| | - Steven B Marston
- National Heart and Lung Institute, Imperial College London, London, UK.
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Papadaki M, Vikhorev PG, Marston SB, Messer AE. Uncoupling of myofilament Ca2+ sensitivity from troponin I phosphorylation by mutations can be reversed by epigallocatechin-3-gallate. Cardiovasc Res 2015; 108:99-110. [PMID: 26109583 DOI: 10.1093/cvr/cvv181] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2014] [Accepted: 06/11/2015] [Indexed: 02/02/2023] Open
Abstract
AIMS Heart muscle contraction is regulated via the β-adrenergic response that leads to phosphorylation of Troponin I (TnI) at Ser22/23, which changes the Ca(2+) sensitivity of the cardiac myofilament. Mutations in thin filament proteins that cause dilated cardiomyopathy (DCM) and some mutations that cause hypertrophic cardiomyopathy (HCM) abolish the relationship between TnI phosphorylation and Ca(2+) sensitivity (uncoupling). Small molecule Ca(2+) sensitizers and Ca(2+) desensitizers that act upon troponin alter the Ca(2+) sensitivity of the thin filament, but their relationship with TnI phosphorylation has never been studied before. METHODS AND RESULTS Quantitative in vitro motility assay showed that 30 µM EMD57033 and 100 µM Bepridil increase Ca(2+) sensitivity of phosphorylated cardiac thin filaments by 3.1- and 2.8-fold, respectively. Additionally they uncoupled Ca(2+) sensitivity from TnI phosphorylation, mimicking the effect of HCM mutations. Epigallocatechin-3-gallate (EGCG) decreased Ca(2+) sensitivity of phosphorylated and unphosphorylated wild-type thin filaments equally (by 2.15 ± 0.45- and 2.80 ± 0.48-fold, respectively), retaining the coupling. Moreover, EGCG also reduced Ca(2+) sensitivity of phosphorylated but not unphosphorylated thin filaments containing DCM and HCM-causing mutations; thus, the dependence of Ca(2+) sensitivity upon TnI phosphorylation of uncoupled mutant thin filaments was restored in every case. In single mouse heart myofibrils, EGCG reduced Ca(2+) sensitivity of force and kACT and also preserved coupling. Myofibrils from the ACTC E361G (DCM) mouse were uncoupled; EGCG reduced Ca(2+) sensitivity more for phosphorylated than for unphosphorylated myofibrils, thus restoring coupling. CONCLUSION We conclude that it is possible to both mimic and reverse the pathological defects in troponin caused by cardiomyopathy mutations pharmacologically. Re-coupling by EGCG may be of potential therapeutic significance for treating cardiomyopathies.
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Affiliation(s)
- Maria Papadaki
- National Heart and Lung Institute, Imperial College London, London W12 0NN, UK
| | - Petr G Vikhorev
- National Heart and Lung Institute, Imperial College London, London W12 0NN, UK
| | - Steven B Marston
- National Heart and Lung Institute, Imperial College London, London W12 0NN, UK
| | - Andrew E Messer
- National Heart and Lung Institute, Imperial College London, London W12 0NN, UK
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McCormick ME, Collins C, Makarewich CA, Chen Z, Rojas M, Willis MS, Houser SR, Tzima E. Platelet endothelial cell adhesion molecule-1 mediates endothelial-cardiomyocyte communication and regulates cardiac function. J Am Heart Assoc 2015; 4:e001210. [PMID: 25600142 PMCID: PMC4330051 DOI: 10.1161/jaha.114.001210] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Background Dilated cardiomyopathy is characterized by impaired contractility of cardiomyocytes, ventricular chamber dilatation, and systolic dysfunction. Although mutations in genes expressed in the cardiomyocyte are the best described causes of reduced contractility, the importance of endothelial‐cardiomyocyte communication for proper cardiac function is increasingly appreciated. In the present study, we investigate the role of the endothelial adhesion molecule platelet endothelial cell adhesion molecule (PECAM‐1) in the regulation of cardiac function. Methods and Results Using cell culture and animal models, we show that PECAM‐1 expressed in endothelial cells (ECs) regulates cardiomyocyte contractility and cardiac function via the neuregulin‐ErbB signaling pathway. Conscious echocardiography revealed left ventricular (LV) chamber dilation and systolic dysfunction in PECAM‐1−/− mice in the absence of histological abnormalities or defects in cardiac capillary density. Despite deficits in global cardiac function, cardiomyocytes isolated from PECAM‐1−/− hearts displayed normal baseline and isoproterenol‐stimulated contractility. Mechanistically, absence of PECAM‐1 resulted in elevated NO/ROS signaling and NRG‐1 release from ECs, which resulted in augmented phosphorylation of its receptor ErbB2. Treatment of cardiomyocytes with conditioned media from PECAM‐1−/− ECs resulted in enhanced ErbB2 activation, which was normalized by pre‐treatment with an NRG‐1 blocking antibody. To determine whether normalization of increased NRG‐1 levels could correct cardiac function, PECAM‐1−/− mice were treated with the NRG‐1 blocking antibody. Echocardiography showed that treatment significantly improved cardiac function of PECAM‐1−/− mice, as revealed by increased ejection fraction and fractional shortening. Conclusions We identify a novel role for PECAM‐1 in regulating cardiac function via a paracrine NRG1‐ErbB pathway. These data highlight the importance of tightly regulated cellular communication for proper cardiac function.
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Affiliation(s)
- Margaret E. McCormick
- Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC (M.E.M.C., C.C., Z.C., E.T.)
| | - Caitlin Collins
- Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC (M.E.M.C., C.C., Z.C., E.T.)
| | - Catherine A. Makarewich
- Cardiovascular Research Center and Department of Physiology, Temple University School of Medicine, Philadelphia, PA (C.A.M., S.R.H.)
| | - Zhongming Chen
- Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC (M.E.M.C., C.C., Z.C., E.T.)
| | - Mauricio Rojas
- McAllister Heart Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC (M.R., E.T.)
| | - Monte S. Willis
- Department of Pathology and Laboratory Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC (M.S.W.)
| | - Steven R. Houser
- Cardiovascular Research Center and Department of Physiology, Temple University School of Medicine, Philadelphia, PA (C.A.M., S.R.H.)
| | - Ellie Tzima
- Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC (M.E.M.C., C.C., Z.C., E.T.)
- McAllister Heart Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC (M.R., E.T.)
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Chang AN, Greenfield NJ, Singh A, Potter JD, Pinto JR. Structural and protein interaction effects of hypertrophic and dilated cardiomyopathic mutations in alpha-tropomyosin. Front Physiol 2014; 5:460. [PMID: 25520664 PMCID: PMC4251307 DOI: 10.3389/fphys.2014.00460] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2014] [Accepted: 11/10/2014] [Indexed: 12/16/2022] Open
Abstract
The potential alterations to structure and associations with thin filament proteins caused by the dilated cardiomyopathy (DCM) associated tropomyosin (Tm) mutants E40K and E54K, and the hypertrophic cardiomyopathy (HCM) associated Tm mutants E62Q and L185R, were investigated. In order to ascertain what the cause of the known functional effects may be, structural and protein-protein interaction studies were conducted utilizing actomyosin ATPase activity measurements and spectroscopy. In actomyosin ATPase measurements, both HCM mutants and the DCM mutant E54K caused increases in Ca2+-induced maximal ATPase activities, while E40K caused a decrease. Investigation of Tm's ability to inhibit actomyosin ATPase in the absence of troponin showed that HCM-associated mutant Tms did not inhibit as well as wildtype, whereas the DCM associated mutant E40K inhibited better. E54K did not inhibit the actomyosin ATPase activity at any concentration of Tm tested. Thermal denaturation studies by circular dichroism and molecular modeling of the mutations in Tm showed that in general, the DCM mutants caused localized destabilization of the Tm dimers, while the HCM mutants resulted in increased stability. These findings demonstrate that the structural alterations in Tm observed here may affect the regulatory function of Tm on actin, thereby directly altering the ATPase rates of myosin.
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Affiliation(s)
- Audrey N Chang
- Department of Molecular and Cellular Pharmacology, Leonard Miller School of Medicine, University of Miami Miami, FL, USA
| | - Norma J Greenfield
- Department of Neuroscience and Cell Biology, Robert Wood Johnson Medical School, Rutgers University New Jersey, NJ, USA
| | - Abhishek Singh
- Department of Neuroscience and Cell Biology, Robert Wood Johnson Medical School, Rutgers University New Jersey, NJ, USA ; Department of Cardiology, UCSF Medical Center, University of California, San Francisco San Francisco, CA, USA
| | - James D Potter
- Department of Molecular and Cellular Pharmacology, Leonard Miller School of Medicine, University of Miami Miami, FL, USA
| | - Jose R Pinto
- Department of Biomedical Sciences, Florida State University College of Medicine Tallahassee, FL, USA
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Abstract
Dilated cardiomyopathy is a disease of the myocardium characterized by left ventricular dilatation and/or dysfunction, affecting both adult and pediatric populations. Almost half of cases are genetically determined with an autosomal pattern of inheritance. Up to 40 genes have been identified affecting proteins of a wide variety of cellular structures such as the sarcomere, the nuclear envelope, the cytoskeleton, the sarcolemma and the intercellular junction. Novel gene mutations have been recently identified thanks to advances in next-generation sequencing technologies. Genetic screening is an essential tool for early diagnosis, risk assessment, prognostic stratification and, possibly, adoption of primary preventive measures in affected patients and their asymptomatic relatives. The purpose of this article is to review the genetic basis of DCM, the known genotype-phenotype correlations, the role of current genetic sequencing techniques in the discovery of novel pathogenic gene mutations and new therapeutic perspectives.
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Affiliation(s)
- Luisa Mestroni
- Cardiovascular Institute and Adult Medical Genetics, University of Colorado Denver, Aurora, Colorado
| | - Francesca Brun
- Cardiovascular Institute and Adult Medical Genetics, University of Colorado Denver, Aurora, Colorado ; Cardiovascular Department "Ospedali Riuniti", Hospital and University of Trieste, Italy
| | - Anita Spezzacatene
- Cardiovascular Institute and Adult Medical Genetics, University of Colorado Denver, Aurora, Colorado ; Cardiovascular Department "Ospedali Riuniti", Hospital and University of Trieste, Italy
| | - Gianfranco Sinagra
- Cardiovascular Department "Ospedali Riuniti", Hospital and University of Trieste, Italy
| | - Matthew Rg Taylor
- Cardiovascular Institute and Adult Medical Genetics, University of Colorado Denver, Aurora, Colorado
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Spudich JA. Hypertrophic and dilated cardiomyopathy: four decades of basic research on muscle lead to potential therapeutic approaches to these devastating genetic diseases. Biophys J 2014; 106:1236-49. [PMID: 24655499 PMCID: PMC3985504 DOI: 10.1016/j.bpj.2014.02.011] [Citation(s) in RCA: 198] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2013] [Revised: 01/30/2014] [Accepted: 02/04/2014] [Indexed: 01/10/2023] Open
Abstract
With the advent of technologies to obtain the complete sequence of the human genome in a cost-effective manner, this decade and those to come will see an exponential increase in our understanding of the underlying genetics that lead to human disease. And where we have a deep understanding of the biochemical and biophysical basis of the machineries and pathways involved in those genetic changes, there are great hopes for the development of modern therapeutics that specifically target the actual machinery and pathways altered by individual mutations. Prime examples of such a genetic disease are those classes of hypertrophic and dilated cardiomyopathy that result from single amino-acid substitutions in one of several of the proteins that make up the cardiac sarcomere or from the truncation of myosin binding protein C. Hypertrophic cardiomyopathy alone affects ∼1 in 500 individuals, and it is the leading cause of sudden cardiac death in young adults. Here I describe approaches to understand the molecular basis of the alterations in power output that result from these mutations. Small molecules binding to the mutant sarcomeric protein complex should be able to mitigate the effects of hypertrophic and dilated cardiomyopathy mutations at their sources, leading to possible new therapeutic approaches for these genetic diseases.
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Affiliation(s)
- James A Spudich
- Department of Biochemistry, Stanford University School of Medicine, Stanford, California.
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41
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Feldman AM, Begay RL, Knezevic T, Myers VD, Slavov DB, Zhu W, Gowan K, Graw SL, Jones KL, Tilley DG, Coleman RC, Walinsky P, Cheung JY, Mestroni L, Khalili K, Taylor MRG. Decreased levels of BAG3 in a family with a rare variant and in idiopathic dilated cardiomyopathy. J Cell Physiol 2014; 229:1697-702. [PMID: 24623017 DOI: 10.1002/jcp.24615] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2014] [Accepted: 03/11/2014] [Indexed: 01/01/2023]
Abstract
The most common cause of dilated cardiomyopathy and heart failure (HF) is ischemic heart disease; however, in a third of all patients the cause remains undefined and patients are diagnosed as having idiopathic dilated cardiomyopathy (IDC). Recent studies suggest that many patients with IDC have a family history of HF and rare genetic variants in over 35 genes have been shown to be causative of disease. We employed whole-exome sequencing to identify the causative variant in a large family with autosomal dominant transmission of dilated cardiomyopathy. Sequencing and subsequent informatics revealed a novel 10-nucleotide deletion in the BCL2-associated athanogene 3 (BAG3) gene (Ch10:del 121436332_12143641: del. 1266_1275 [NM 004281]) that segregated with all affected individuals. The deletion predicted a shift in the reading frame with the resultant deletion of 135 amino acids from the C-terminal end of the protein. Consistent with genetic variants in genes encoding other sarcomeric proteins there was a considerable amount of genetic heterogeneity in the affected family members. Interestingly, we also found that the levels of BAG3 protein were significantly reduced in the hearts from unrelated patients with end-stage HF undergoing cardiac transplantation when compared with non-failing controls. Diminished levels of BAG3 protein may be associated with both familial and non-familial forms of dilated cardiomyopathy.
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Affiliation(s)
- Arthur M Feldman
- Departments of Medicine Neuroscience Physiology and Pharmacology, Temple University School of Medicine, Philadelphia, Pennsylvania
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Liu Z, Li W, Ma X, Ding N, Spallotta F, Southon E, Tessarollo L, Gaetano C, Mukouyama YS, Thiele CJ. Essential role of the zinc finger transcription factor Casz1 for mammalian cardiac morphogenesis and development. J Biol Chem 2014; 289:29801-16. [PMID: 25190801 DOI: 10.1074/jbc.m114.570416] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Chromosome 1p36 deletion syndrome is one of the most common terminal deletions observed in humans and is related to congenital heart disease (CHD). However, the 1p36 genes that contribute to heart disease have not been clearly delineated. Human CASZ1 gene localizes to 1p36 and encodes a zinc finger transcription factor. Casz1 is required for Xenopus heart ventral midline progenitor cell differentiation. Whether Casz1 plays a role during mammalian heart development is unknown. Our aim is to determine 1p36 gene CASZ1 function at regulating heart development in mammals. We generated a Casz1 knock-out mouse using Casz1-trapped embryonic stem cells. Casz1 deletion in mice resulted in abnormal heart development including hypoplasia of myocardium, ventricular septal defect, and disorganized morphology. Hypoplasia of myocardium was caused by decreased cardiomyocyte proliferation. Comparative genome-wide RNA transcriptome analysis of Casz1 depleted embryonic hearts identifies abnormal expression of genes that are critical for muscular system development and function, such as muscle contraction genes TNNI2, TNNT1, and CKM; contractile fiber gene ACTA1; and cardiac arrhythmia associated ion channel coding genes ABCC9 and CACNA1D. The transcriptional regulation of some of these genes by Casz1 was also found in cellular models. Our results showed that loss of Casz1 during mouse development led to heart defect including cardiac noncompaction and ventricular septal defect, which phenocopies 1p36 deletion syndrome related CHD. This suggests that CASZ1 is a novel 1p36 CHD gene and that the abnormal expression of cardiac morphogenesis and contraction genes induced by loss of Casz1 contributes to the heart defect.
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Affiliation(s)
| | - Wenling Li
- the Laboratories of Stem Cell and Neuro-vascular Biology and
| | - Xuefei Ma
- the Molecular Cardiology, NHLBI, National Institutes of Health, Bethesda, Maryland 20892, and
| | | | - Francesco Spallotta
- the Division of Cardiovascular Epigenetics, Department of Cardiology, Goethe University, Frankfurt am Main 60596, Germany
| | - Eileen Southon
- the Mouse Cancer Genetics Program, Neural Development Section, National Cancer Institute, Bethesda, Maryland 20892
| | - Lino Tessarollo
- the Mouse Cancer Genetics Program, Neural Development Section, National Cancer Institute, Bethesda, Maryland 20892
| | - Carlo Gaetano
- the Division of Cardiovascular Epigenetics, Department of Cardiology, Goethe University, Frankfurt am Main 60596, Germany
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Messer AE, Marston SB. Investigating the role of uncoupling of troponin I phosphorylation from changes in myofibrillar Ca(2+)-sensitivity in the pathogenesis of cardiomyopathy. Front Physiol 2014; 5:315. [PMID: 25202278 PMCID: PMC4142463 DOI: 10.3389/fphys.2014.00315] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2014] [Accepted: 08/02/2014] [Indexed: 12/12/2022] Open
Abstract
Contraction in the mammalian heart is controlled by the intracellular Ca(2+) concentration as it is in all striated muscle, but the heart has an additional signaling system that comes into play to increase heart rate and cardiac output during exercise or stress. β-adrenergic stimulation of heart muscle cells leads to release of cyclic-AMP and the activation of protein kinase A which phosphorylates key proteins in the sarcolemma, sarcoplasmic reticulum and contractile apparatus. Troponin I (TnI) and Myosin Binding Protein C (MyBP-C) are the prime targets in the myofilaments. TnI phosphorylation lowers myofibrillar Ca(2+)-sensitivity and increases the speed of Ca(2+)-dissociation and relaxation (lusitropic effect). Recent studies have shown that this relationship between Ca(2+)-sensitivity and TnI phosphorylation may be unstable. In familial cardiomyopathies, both dilated and hypertrophic (DCM and HCM), a mutation in one of the proteins of the thin filament often results in the loss of the relationship (uncoupling) and blunting of the lusitropic response. For familial dilated cardiomyopathy in thin filament proteins it has been proposed that this uncoupling is causative of the phenotype. Uncoupling has also been found in human heart tissue from patients with hypertrophic obstructive cardiomyopathy as a secondary effect. Recently, it has been found that Ca(2+)-sensitizing drugs can promote uncoupling, whilst one Ca(2+)-desensitizing drug Epigallocatechin 3-Gallate (EGCG) can reverse uncoupling. We will discuss recent findings about the role of uncoupling in the development of cardiomyopathies and the molecular mechanism of the process.
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Affiliation(s)
- Andrew E. Messer
- National Heart & Lung Institute, Imperial College LondonLondon, UK
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44
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Wilson K, Lucchesi PA. Myofilament dysfunction as an emerging mechanism of volume overload heart failure. Pflugers Arch 2014; 466:1065-77. [PMID: 24488008 DOI: 10.1007/s00424-014-1455-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2014] [Revised: 01/17/2014] [Accepted: 01/19/2014] [Indexed: 11/28/2022]
Abstract
Two main hemodynamic overload mechanisms [i.e., volume and pressure overload (VO and PO, respectively] result in heart failure (HF), and these two mechanisms have divergent pathologic alterations and different pathophysiological mechanisms. Extensive evidence from animal models and human studies of PO demonstrate a clear association with alterations in Ca(2+) homeostasis. By contrast, emerging evidence from animal models and patients with regurgitant valve disease and dilated cardiomyopathy point toward a more prominent role of myofilament dysfunction. With respect to VO HF, key features of excitation-contraction coupling defects, myofilament dysfunction, and extracellular matrix composition will be discussed.
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Affiliation(s)
- Kristin Wilson
- Center for Cardiovascular and Pulmonary Research and The Heart Center, Nationwide Children's Hospital, Columbus, OH, USA
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45
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Kaushik G, Engler AJ. From stem cells to cardiomyocytes: the role of forces in cardiac maturation, aging, and disease. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2014; 126:219-42. [PMID: 25081620 DOI: 10.1016/b978-0-12-394624-9.00009-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Stem cell differentiation into a variety of lineages is known to involve signaling from the extracellular niche, including from the physical properties of that environment. What regulates stem cell responses to these cues is there ability to activate different mechanotransductive pathways. Here, we will review the structures and pathways that regulate stem cell commitment to a cardiomyocyte lineage, specifically examining proteins within muscle sarcomeres, costameres, and intercalated discs. Proteins within these structures stretch, inducing a change in their phosphorylated state or in their localization to initiate different signals. We will also put these changes in the context of stem cell differentiation into cardiomyocytes, their subsequent formation of the chambered heart, and explore negative signaling that occurs during disease.
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Affiliation(s)
- Gaurav Kaushik
- Department of Bioengineering, University of California, San Diego, La Jolla, California, USA
| | - Adam J Engler
- Department of Bioengineering, University of California, San Diego, La Jolla, California, USA
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Kirwan JP, Hodges RS. Transmission of stability information through the N-domain of tropomyosin is interrupted by a stabilizing mutation (A109L) in the hydrophobic core of the stability control region (residues 97-118). J Biol Chem 2013; 289:4356-66. [PMID: 24362038 PMCID: PMC3924298 DOI: 10.1074/jbc.m113.507236] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Tropomyosin (Tm) is an actin-binding, thin filament, two-stranded α-helical coiled-coil critical for muscle contraction and cytoskeletal function. We made the first identification of a stability control region (SCR), residues 97-118, in the Tm sequence that controls overall protein stability but is not required for folding. We also showed that the individual α-helical strands of the coiled-coil are stabilized by Leu-110, whereas the hydrophobic core is destabilized in the SCR by Ala residues at three consecutive d positions. Our hypothesis is that the stabilization of the individual α-helices provides an optimum stability and allows functionally beneficial dynamic motion between the α-helices that is critical for the transmission of stabilizing information along the coiled-coil from the SCR. We prepared three recombinant (rat) Tm(1-131) proteins, including the wild type sequence, a destabilizing mutation L110A, and a stabilizing mutation A109L. These proteins were evaluated by circular dichroism (CD) and differential scanning calorimetry. The single mutation L110A destabilizes the entire Tm(1-131) molecule, showing that the effect of this mutation is transmitted 165 Å along the coiled-coil in the N-terminal direction. The single mutation A109L prevents the SCR from transmitting stabilizing information and separates the coiled-coil into two domains, one that is ∼9 °C more stable than wild type and one that is ∼16 °C less stable. We know of no other example of the substitution of a stabilizing Leu residue in a coiled-coil hydrophobic core position d that causes this dramatic effect. We demonstrate the importance of the SCR in controlling and transmitting the stability signal along this rodlike molecule.
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Affiliation(s)
- J Paul Kirwan
- From the Program in Structural Biology and Biophysics, Department of Biochemistry and Molecular Genetics, School of Medicine, University of Colorado Denver, Aurora, Colorado 80045
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Merlo M, Sinagra G, Carniel E, Slavov D, Zhu X, Barbati G, Spezzacatene A, Ramani F, Salcedo E, Di Lenarda A, Mestroni L, Taylor MRG. Poor prognosis of rare sarcomeric gene variants in patients with dilated cardiomyopathy. Clin Transl Sci 2013; 6:424-8. [PMID: 24119082 DOI: 10.1111/cts.12116] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND In dilated cardiomyopathy (DCM), the clinical and prognostic implications of rare variants in sarcomeric genes remain poorly understood. To address this question, we analyzed the outcome of rare sarcomeric gene variants in patients enrolled in our Familial Cardiomyopathy Registry. METHODS DCM families harboring rare sarcomeric variants in MYH6, MYH7, MYBPC3, TNNT2, and TTN were identified. Genotype-phenotype association analysis was performed, and long-term survival-free from death or heart transplant was compared between carriers and noncarriers. RESULTS We found 24 rare variants (3 in MYH6, 3 in MYH7, 3 in MYBPC3, 2 in TNNT2, and 13 in TTN) affecting 52 subjects in 25 families. The phenotypes of variant carriers were severe (3 sudden deaths, 6 heart failure deaths, 8 heart transplants, 2 ventricular fibrillations). There was no difference in the overall long-term survival between carriers and the 33 noncarriers (p = 0.322). However after 50 years of age, the combined endpoint of death or transplant was decreased in carriers as compared to noncarriers (p = 0.026). CONCLUSIONS Patients with DCM carrying rare variants in sarcomeric genes manifest a poorer prognosis as compared to noncarriers after the age of 50 years. These data further support the role of genetic testing in DCM for risk stratification.
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Affiliation(s)
- Marco Merlo
- Cardiovascular Institute and Adult Medical Genetics, University of Colorado, Aurora, Colorado, USA; Cardiovascular Department "Ospedali Riuniti,"and University of Trieste, Trieste, Italy
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Razzaque MA, Gupta M, Osinska H, Gulick J, Blaxall BC, Robbins J. An endogenously produced fragment of cardiac myosin-binding protein C is pathogenic and can lead to heart failure. Circ Res 2013; 113:553-61. [PMID: 23852539 DOI: 10.1161/circresaha.113.301225] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
RATIONALE A stable 40-kDa fragment is produced from cardiac myosin-binding protein C when the heart is stressed using a stimulus, such as ischemia-reperfusion injury. Elevated levels of the fragment can be detected in the diseased mouse and human heart, but its ability to interfere with normal cardiac function in the intact animal is unexplored. OBJECTIVE To understand the potential pathogenicity of the 40-kDa fragment in vivo and to investigate the molecular pathways that could be targeted for potential therapeutic intervention. METHODS AND RESULTS We generated cardiac myocyte-specific transgenic mice using a Tet-Off inducible system to permit controlled expression of the 40-kDa fragment in cardiomyocytes. When expression of the 40-kDa protein is induced by crossing the responder animals with tetracycline transactivator mice under conditions in which substantial quantities approximating those observed in diseased hearts are reached, the double-transgenic mice subsequently experience development of sarcomere dysgenesis and altered cardiac geometry, and the heart fails between 12 and 17 weeks of age. The induced double-transgenic mice had development of cardiac hypertrophy with myofibrillar disarray and fibrosis, in addition to activation of pathogenic MEK-ERK pathways. Inhibition of MEK-ERK signaling was achieved by injection of the mitogen-activated protein kinase (MAPK)/ERK inhibitor U0126. The drug effectively improved cardiac function, normalized heart size, and increased probability of survival. CONCLUSIONS These results suggest that the 40-kDa cardiac myosin-binding protein C fragment, which is produced at elevated levels during human cardiac disease, is a pathogenic fragment that is sufficient to cause hypertrophic cardiomyopathy and heart failure.
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Affiliation(s)
- Md Abdur Razzaque
- Department of Pediatrics, The Heart Institute, The Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
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A study of tropomyosin's role in cardiac function and disease using thin-filament reconstituted myocardium. J Muscle Res Cell Motil 2013; 34:295-310. [PMID: 23700264 DOI: 10.1007/s10974-013-9343-z] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2013] [Accepted: 05/07/2013] [Indexed: 10/26/2022]
Abstract
Tropomyosin (Tm) is the key regulatory component of the thin-filament and plays a central role in the cardiac muscle's cooperative activation mechanism. Many mutations of cardiac Tm are related to hypertrophic cardiomyopathy (HCM), dilated cardiomyopathy (DCM), and left ventricular noncompaction (LVNC). Using the thin-filament extraction/reconstitution technique, we are able to incorporate various Tm mutants and protein isoforms into a muscle fiber environment to study their roles in Ca(2+) regulation, cross-bridge kinetics, and force generation. The thin-filament reconstitution technique poses several advantages compared to other in vitro and in vivo methods: (1) Tm mutants and isoforms are placed into the real muscle fiber environment to exhibit their effect on a level much higher than simple protein complexes; (2) only the primary and immediate effects of Tm mutants are studied in the thin-filament reconstituted myocardium; (3) lethal mutants of Tm can be studied without causing a problem; and (4) inexpensive. In transgenic models, various secondary effects (myocyte disarray, ECM fibrosis, altered protein phosphorylation levels, etc.) also affect the performance of the myocardium, making it very difficult to isolate the primary effect of the mutation. Our studies on Tm have demonstrated that: (1) Tm positively enhances the hydrophobic interaction between actin and myosin in the "closed state", which in turn enhances the isometric tension; (2) Tm's seven periodical repeats carry distinct functions, with the 3rd period being essential for the tension enhancement; (3) Tm mutants lead to HCM by impairing the relaxation on one hand, and lead to DCM by over inhibition of the AM interaction on the other hand. Ca(2+) sensitivity is affected by inorganic phosphate, ionic strength, and phosphorylation of constituent proteins; hence it may not be the primary cause of the pathogenesis. Here, we review our current knowledge regarding Tm's effect on the actomyosin interaction and the early molecular pathogenesis of Tm mutation related to HCM, DCM, and LVNC.
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Memo M, Leung MC, Ward DG, dos Remedios C, Morimoto S, Zhang L, Ravenscroft G, McNamara E, Nowak KJ, Marston SB, Messer AE. Familial dilated cardiomyopathy mutations uncouple troponin I phosphorylation from changes in myofibrillar Ca²⁺ sensitivity. Cardiovasc Res 2013; 99:65-73. [PMID: 23539503 DOI: 10.1093/cvr/cvt071] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
AIMS The pure form of familial dilated cardiomyopathy (DCM) is mainly caused by mutations in genes encoding sarcomeric proteins. Previous measurements using recombinant proteins suggested that DCM mutations in thin filament proteins decreased myofibrillar Ca(2+) sensitivity, but exceptions were reported. We re-investigated the molecular mechanism of familial DCM using native proteins. METHODS AND RESULTS We used the quantitative in vitro motility assay and native troponin and tropomyosin to study DCM mutations in troponin I, troponin T, and α-tropomyosin. Four mutations reduced myofilament Ca(2+) sensitivity, but one mutation (TPM1 E54K) did not alter Ca(2+) sensitivity and another (TPM1 D230N) increased Ca(2+) sensitivity. In thin filaments from normal human and mouse heart, protein kinase A (PKA) phosphorylation of troponin I caused a two- to three-fold decrease in myofibrillar Ca(2+) sensitivity. However, Ca(2+) sensitivity did not change with the level of troponin I phosphorylation in any of the DCM-mutant containing thin filaments (E40K, E54K, and D230N in α-tropomyosin; R141W and ΔK210 in cardiac troponin T; K36Q in cardiac troponin I; G159D in cardiac troponin C, and E361G in cardiac α-actin). This 'uncoupling' was observed with native mutant protein from human and mouse heart and with recombinant mutant protein expressed in baculovirus/Sf9 systems. Uncoupling was independent of the fraction of mutated protein present above 0.55. CONCLUSION We conclude that DCM-causing mutations in thin filament proteins abolish the relationship between myofilament Ca(2+) sensitivity and troponin I phosphorylation by PKA. We propose that this blunts the response to β-adrenergic stimulation and could be the cause of DCM in the long term.
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Affiliation(s)
- Massimiliano Memo
- Myocardial Function, NHLI, Imperial College London, London, W12 0NN, UK
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