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Dutton LC, Dudhia J, Guest DJ, Connolly DJ. CRISPR/Cas9 gene editing in induced pluripotent stem cells to investigate the feline hypertrophic cardiomyopathy causing MYBPC3/R820W mutation. PLoS One 2024; 19:e0311761. [PMID: 39388496 PMCID: PMC11466433 DOI: 10.1371/journal.pone.0311761] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2024] [Accepted: 09/24/2024] [Indexed: 10/12/2024] Open
Abstract
Hypertrophic cardiomyopathy (HCM) is the most common heart disease in domestic cats, often leading to congestive heart failure and death, with current treatment strategies unable to reverse or prevent progression of the disease. The underlying pathological processes driving HCM remain unclear, which hinders novel drug discovery. The aim of this study was to generate a cellular model of the feline HCM-causing MYBPC3 mutation R820W. Using CRISPR/Cas9 gene editing we introduced the R820W mutation into a human induced pluripotent stem cell (iPSC) line. We differentiated both homozygous mutant clones and isogenic control clones to cardiomyocytes (iPSC-CMs). Protein quantification indicated that haploinsufficiency is not the disease mechanism of the mutation. Homozygous mutant iPSC-CMs had a larger cell area than isogenic controls, with the sarcomere structure and incorporation of cMyBP-C appearing similar between mutant and control iPSC-CMs. Contraction kinetic analysis indicated that homozygous iPSC-CMs have impaired relaxation and are hypocontractile compared to isogenic control iPSC-CMs. In summary, we demonstrate successful generation of an iPSC model of a feline MYBPC3 mutation, with the cellular model recapitulating aspects of HCM including cellular hypertrophy and impaired relaxation kinetics. We anticipate that further study of this model will lead to improved understanding of the disease-causing molecular mechanism, ultimately leading to novel drug discovery.
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Affiliation(s)
- Luke C. Dutton
- Department of Clinical Science and Services, Royal Veterinary College, Hatfield, London, United Kingdom
| | - Jayesh Dudhia
- Department of Clinical Science and Services, Royal Veterinary College, Hatfield, London, United Kingdom
| | - Deborah J. Guest
- Department of Clinical Science and Services, Royal Veterinary College, Hatfield, London, United Kingdom
| | - David J. Connolly
- Department of Clinical Science and Services, Royal Veterinary College, Hatfield, London, United Kingdom
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2
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Spudich JA, Nandwani N, Robert-Paganin J, Houdusse A, Ruppel KM. Reassessing the unifying hypothesis for hypercontractility caused by myosin mutations in hypertrophic cardiomyopathy. EMBO J 2024; 43:4139-4155. [PMID: 39192034 PMCID: PMC11445530 DOI: 10.1038/s44318-024-00199-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2024] [Revised: 07/12/2024] [Accepted: 07/18/2024] [Indexed: 08/29/2024] Open
Affiliation(s)
- James A Spudich
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA, 94305, USA.
| | - Neha Nandwani
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA, 94305, USA
| | - Julien Robert-Paganin
- Structural Motility, Institut Curie, Paris Université Sciences et Lettres, Sorbonne Université, CNRS UMR144, F-75005, Paris, France
| | - Anne Houdusse
- Structural Motility, Institut Curie, Paris Université Sciences et Lettres, Sorbonne Université, CNRS UMR144, F-75005, Paris, France
| | - Kathleen M Ruppel
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA, 94305, USA.
- Department of Pediatrics, Stanford University School of Medicine, Stanford, CA, 94305, USA.
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3
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Tanner BCW. Design Principles and Benefits of Spatially Explicit Models of Myofilament Function. Methods Mol Biol 2024; 2735:43-62. [PMID: 38038843 DOI: 10.1007/978-1-0716-3527-8_4] [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] [Indexed: 12/02/2023]
Abstract
Spatially explicit models of muscle contraction include fine-scale details about the spatial, kinetic, and/or mechanical properties of the biological processes being represented within the model network. Over the past 25 years, this has primarily consisted of a set of mathematical and computational algorithms representing myosin cross-bridge activity, Ca2+-activation of contraction, and ensemble force production within a half-sarcomere representation of the myofilament network. Herein we discuss basic design principles associated with creating spatially explicit models of myofilament function, as well as model assumptions underlying model development. A brief overview of computational approaches is introduced. Opportunities for new model directions that could investigate coupled regulatory pathways between the thick-filament and thin-filaments are also presented. Given the modular design and flexibility associated with spatially explicit models, we highlight some advantages of this approach compared to other model formulations.
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Affiliation(s)
- Bertrand C W Tanner
- Department of Integrative Physiology and Neuroscience, Washington State University, Pullman, WA, USA.
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4
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Bergonzo C, Aryal B, Rao VA. Divalent ions as mediators of carbonylation in cardiac myosin binding protein C. J Mol Graph Model 2023; 124:108576. [PMID: 37536231 DOI: 10.1016/j.jmgm.2023.108576] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Revised: 07/12/2023] [Accepted: 07/27/2023] [Indexed: 08/05/2023]
Abstract
The dosing and efficacy of chemotherapeutic drugs can be limited by toxicity caused by off-pathway reactions. One hypothesis for how such toxicity arises is via metal-catalyzed oxidative damage of cardiac myosin binding protein C (cMyBP-C) found in cardiac tissue. Previous research indicates that metal ion mediated reactive oxygen species induce high levels of protein carbonylation, changing the structure and function of this protein. In this work, we use long timescale all-atom molecular dynamics simulations to investigate the ion environment surrounding the C0 and C1 subunits of cMyBP-C responsible for actin binding. We show that divalent cations are co-localized with protein carbonylation-prone amino acid residues and that carbonylation of these residues can lead to site-specific interruption to the actin-cMyBP-C binding.
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Affiliation(s)
- Christina Bergonzo
- Institute for Bioscience and Biotechnology Research, National Institute of Standards and Technology, the University of Maryland, 9600 Gudelsky Way, Rockville, MD, 20850, USA.
| | - Baikuntha Aryal
- Laboratory of Applied Biochemistry, Division of Biotechnology Review and Research III, Office of Biotechnology Products, Office of Pharmaceutical Quality, Center for Drug Evaluation and Research, U.S. Food and Drug Administration, Silver Spring, MD, USA
| | - V Ashutosh Rao
- Laboratory of Applied Biochemistry, Division of Biotechnology Review and Research III, Office of Biotechnology Products, Office of Pharmaceutical Quality, Center for Drug Evaluation and Research, U.S. Food and Drug Administration, Silver Spring, MD, USA
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5
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Masania J, Wijten P, Keipert S, Ost M, Klaus S, Rabbani N, Thornalley PJ. Decreased methylglyoxal-mediated protein glycation in the healthy aging mouse model of ectopic expression of UCP1 in skeletal muscle. Redox Biol 2023; 59:102574. [PMID: 36521306 PMCID: PMC9772855 DOI: 10.1016/j.redox.2022.102574] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Revised: 12/05/2022] [Accepted: 12/05/2022] [Indexed: 12/12/2022] Open
Abstract
Mice with ectopic expression of uncoupling protein-1 (UCP1) in skeletal muscle exhibit a healthy aging phenotype with increased longevity and resistance to impaired metabolic health. This may be achieved by decreasing protein glycation by the reactive metabolite, methylglyoxal (MG). We investigated protein glycation and oxidative damage in skeletal muscle of mice with UCP1 expression under control of the human skeletal actin promoter (HSA-mUCP1) at age 12 weeks (young) and 70 weeks (aged). We found both young and aged HSA-mUCP1 mice had decreased advanced glycation endproducts (AGEs) formed from MG, lysine-derived Nε(1-carboxyethyl)lysine (CEL) and arginine-derived hydroimidazolone, MG-H1, whereas protein glycation by glucose forming Nε-fructosyl-lysine (FL) was increased ca. 2-fold, compared to wildtype controls. There were related increases in FL-linked AGEs, Nε-carboxymethyl-lysine (CML) and 3-deoxylglucosone-derived hydroimidazolone 3DG-H, and minor changes in protein oxidative and nitration adducts. In aged HSA-mUCP1 mice, urinary MG-derived AGEs/FL ratio was decreased ca. 60% whereas there was no change in CML/FL ratio - a marker of oxidative damage. This suggests that, normalized for glycemic status, aged HSA-mUCP1 mice had a lower flux of whole body MG-derived AGE exposure compared to wildtype controls. Proteomics analysis of skeletal muscle revealed a shift to increased heat shock proteins and mechanoprotection and repair in HSA-mUCP1 mice. Decreased MG-derived AGE protein content in skeletal muscle of aged HSA-mUCP1 mice is therefore likely produced by increased proteolysis of MG-modified proteins and increased proteostasis surveillance of the skeletal muscle proteome. From this and previous transcriptomic studies, signaling involved in enhanced removal of MG-modified protein is likely increased HSPB1-directed HUWE1 ubiquitination through eIF2α-mediated, ATF5-induced increased expression of HSPB1. Decreased whole body exposure to MG-derived AGEs may be linked to increased weight specific physical activity of HSA-mUCP1 mice. Decreased formation and increased clearance of MG-derived AGEs may be associated with healthy aging in the HSA-mUCP1 mouse.
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Affiliation(s)
- Jinit Masania
- Clinical Sciences Research Laboratories, Warwick Medical School, University of Warwick, University Hospital, Coventry, CV2 2DX, UK
| | - Patrick Wijten
- Diabetes Research Center, Qatar Biomedical Research Institute, Hamad Bin Khalifa University, Qatar Foundation, P.O. Box 34110, Doha, Qatar
| | - Susanne Keipert
- Department of Physiology of Energy Metabolism, German Institute of Human Nutrition, Potsdam-Rehbruecke, 14558, Nuthetal, Germany
| | - Mario Ost
- Department of Physiology of Energy Metabolism, German Institute of Human Nutrition, Potsdam-Rehbruecke, 14558, Nuthetal, Germany
| | - Susanne Klaus
- Department of Physiology of Energy Metabolism, German Institute of Human Nutrition, Potsdam-Rehbruecke, 14558, Nuthetal, Germany; University of Potsdam, Institute of Nutrition Science, Potsdam-Rehbruecke, 14558, Nuthetal, Germany
| | - Naila Rabbani
- Department of Basic Medical Science, College of Medicine, QU Health, Qatar University, P.O. Box 2713, Doha, Qatar
| | - Paul J Thornalley
- Clinical Sciences Research Laboratories, Warwick Medical School, University of Warwick, University Hospital, Coventry, CV2 2DX, UK; Diabetes Research Center, Qatar Biomedical Research Institute, Hamad Bin Khalifa University, Qatar Foundation, P.O. Box 34110, Doha, Qatar.
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6
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Suay-Corredera C, Alegre-Cebollada J. The mechanics of the heart: zooming in on hypertrophic cardiomyopathy and cMyBP-C. FEBS Lett 2022; 596:703-746. [PMID: 35224729 DOI: 10.1002/1873-3468.14301] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Revised: 01/10/2022] [Accepted: 01/14/2022] [Indexed: 11/10/2022]
Abstract
Hypertrophic cardiomyopathy (HCM), a disease characterized by cardiac muscle hypertrophy and hypercontractility, is the most frequently inherited disorder of the heart. HCM is mainly caused by variants in genes encoding proteins of the sarcomere, the basic contractile unit of cardiomyocytes. The most frequently mutated among them is MYBPC3, which encodes cardiac myosin-binding protein C (cMyBP-C), a key regulator of sarcomere contraction. In this review, we summarize clinical and genetic aspects of HCM and provide updated information on the function of the healthy and HCM sarcomere, as well as on emerging therapeutic options targeting sarcomere mechanical activity. Building on what is known about cMyBP-C activity, we examine different pathogenicity drivers by which MYBPC3 variants can cause disease, focussing on protein haploinsufficiency as a common pathomechanism also in nontruncating variants. Finally, we discuss recent evidence correlating altered cMyBP-C mechanical properties with HCM development.
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7
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Burghardt TP. Natural variant frequencies across domains from different sarcomere proteins cross-correlate to identify inter-protein contacts associated with cardiac muscle function and disease. MOLECULAR BIOMEDICINE 2021; 2:35. [PMID: 35006463 PMCID: PMC8607394 DOI: 10.1186/s43556-021-00056-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Accepted: 09/23/2021] [Indexed: 12/15/2022] Open
Abstract
Coordinated sarcomere proteins produce contraction force for muscle shortening. In human ventriculum they include the cardiac myosin motor (βmys), repetitively converting ATP free energy into work, and myosin binding protein C (MYBPC3) that in complex with βmys is regulatory. Single nucleotide variants (SNVs) causing hereditary heart diseases frequently target this protein pair. The βmys/MYBPC3 complex models a regulated motor and is used here to study how the proteins couple. SNVs in βmys or MYBPC3 survey human populations worldwide. Their protein expression modifies domain structure affecting phenotype and pathogenicity outcomes. When the SNV modified domain locates to inter-protein contacts it could affect complex coordination. Domains involved, one in βmys the other in MYBPC3, form coordinated domains (co-domains). Co-domain bilateral structure implies the possibility for a shared impact from SNV modification in either domain suggesting a correlated response to a common perturbation could identify their location. Genetic divergence over human populations is proposed to perturb SNV probability coupling that is detected by cross-correlation in 2D correlation genetics (2D-CG). SNV probability data and 2D-CG identify three critical sites, two in MYBPC3 with links to several domains across the βmys motor, and, one in βmys with links to the MYBPC3 regulatory domain. MYBPC3 sites are hinges sterically enabling regulatory interactions with βmys. The βmys site is the actin binding C-loop (residues 359-377). The C-loop is a trigger for actin-activated myosin ATPase and a contraction velocity modulator. Co-domain identification implies their spatial proximity suggesting a novel approach for in vivo protein complex structure determination.
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Affiliation(s)
- Thomas P Burghardt
- Department of Biochemistry and Molecular Biology, Mayo Clinic Rochester, 200 First St. SW, Rochester, MN, 55905, USA.
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8
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Risi CM, Patra M, Belknap B, Harris SP, White HD, Galkin VE. Interaction of the C2 Ig-like Domain of Cardiac Myosin Binding Protein-C with F-actin. J Mol Biol 2021; 433:167178. [PMID: 34329643 PMCID: PMC8453104 DOI: 10.1016/j.jmb.2021.167178] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Revised: 06/29/2021] [Accepted: 07/19/2021] [Indexed: 10/20/2022]
Abstract
Cardiac muscle contraction depends on interactions between thick (myosin) and thin (actin) filaments (TFs). TFs are regulated by intracellular Ca2+ levels. Under activating conditions Ca2+ binds to the troponin complex and displaces tropomyosin from myosin binding sites on the TF surface to allow actomyosin interactions. Recent studies have shown that in addition to Ca2+, the first four N-terminal domains (NTDs) of cardiac myosin binding protein C (cMyBP-C) (e.g. C0, C1, M and C2), are potent modulators of the TF activity, but the mechanism of their collective action is poorly understood. Previously, we showed that C1 activates the TF at low Ca2+ and C0 stabilizes binding of C1 to the TF, but the ability of C2 to bind and/or affect the TF remains unknown. Here we obtained 7.5 Å resolution cryo-EM reconstruction of C2-decorated actin filaments to demonstrate that C2 binds to actin in a single structural mode that does not activate the TF unlike the polymorphic binding of C0 and C1 to actin. Comparison of amino acid sequences of C2 with either C0 or C1 shows low levels of identity between the residues involved in interactions with the TF but high levels of conservation for residues involved in Ig fold stabilization. This provides a structural basis for strikingly different interactions of structurally homologous C0, C1 and C2 with the TF. Our detailed analysis of the interaction of C2 with the actin filament provides crucial information required to model the collective action of cMyBP-C NTDs on the cardiac TF.
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Affiliation(s)
- Cristina M Risi
- Department of Physiological Sciences, Eastern Virginia Medical School, Norfolk, VA 23507, USA
| | - Malay Patra
- Department of Physiological Sciences, Eastern Virginia Medical School, Norfolk, VA 23507, USA
| | - Betty Belknap
- Department of Physiological Sciences, Eastern Virginia Medical School, Norfolk, VA 23507, USA
| | - Samantha P Harris
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85724, USA
| | - Howard D White
- Department of Physiological Sciences, Eastern Virginia Medical School, Norfolk, VA 23507, USA
| | - Vitold E Galkin
- Department of Physiological Sciences, Eastern Virginia Medical School, Norfolk, VA 23507, USA.
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9
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Lynch TL, Kumar M, McNamara JW, Kuster DWD, Sivaguru M, Singh RR, Previs MJ, Lee KH, Kuffel G, Zilliox MJ, Lin BL, Ma W, Gibson AM, Blaxall BC, Nieman ML, Lorenz JN, Leichter DM, Leary OP, Janssen PML, de Tombe PP, Gilbert RJ, Craig R, Irving T, Warshaw DM, Sadayappan S. Amino terminus of cardiac myosin binding protein-C regulates cardiac contractility. J Mol Cell Cardiol 2021; 156:33-44. [PMID: 33781820 PMCID: PMC8217138 DOI: 10.1016/j.yjmcc.2021.03.009] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Revised: 03/21/2021] [Accepted: 03/22/2021] [Indexed: 12/12/2022]
Abstract
Phosphorylation of cardiac myosin binding protein-C (cMyBP-C) regulates cardiac contraction through modulation of actomyosin interactions mediated by the protein's amino terminal (N')-region (C0-C2 domains, 358 amino acids). On the other hand, dephosphorylation of cMyBP-C during myocardial injury results in cleavage of the 271 amino acid C0-C1f region and subsequent contractile dysfunction. Yet, our current understanding of amino terminus region of cMyBP-C in the context of regulating thin and thick filament interactions is limited. A novel cardiac-specific transgenic mouse model expressing cMyBP-C, but lacking its C0-C1f region (cMyBP-C∆C0-C1f), displayed dilated cardiomyopathy, underscoring the importance of the N'-region in cMyBP-C. Further exploring the molecular basis for this cardiomyopathy, in vitro studies revealed increased interfilament lattice spacing and rate of tension redevelopment, as well as faster actin-filament sliding velocity within the C-zone of the transgenic sarcomere. Moreover, phosphorylation of the unablated phosphoregulatory sites was increased, likely contributing to normal sarcomere morphology and myoarchitecture. These results led us to hypothesize that restoration of the N'-region of cMyBP-C would return actomyosin interaction to its steady state. Accordingly, we administered recombinant C0-C2 (rC0-C2) to permeabilized cardiomyocytes from transgenic, cMyBP-C null, and human heart failure biopsies, and we found that normal regulation of actomyosin interaction and contractility was restored. Overall, these data provide a unique picture of selective perturbations of the cardiac sarcomere that either lead to injury or adaptation to injury in the myocardium.
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Affiliation(s)
- Thomas L Lynch
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, IL 60153, USA
| | - Mohit Kumar
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, IL 60153, USA; Heart, Lung and Vascular Institute, Division of Cardiovascular Health and Disease, Department of Internal Medicine, University of Cincinnati, Cincinnati, OH 45267, USA
| | - James W McNamara
- Heart, Lung and Vascular Institute, Division of Cardiovascular Health and Disease, Department of Internal Medicine, University of Cincinnati, Cincinnati, OH 45267, USA
| | - Diederik W D Kuster
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, IL 60153, USA; Department of Physiology, Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam Cardiovascular Sciences, Amsterdam, the Netherlands
| | - Mayandi Sivaguru
- Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Rohit R Singh
- Heart, Lung and Vascular Institute, Division of Cardiovascular Health and Disease, Department of Internal Medicine, University of Cincinnati, Cincinnati, OH 45267, USA
| | - Michael J Previs
- Department of Molecular Physiology and Biophysics, Cardiovascular Research Institute, University of Vermont, Burlington, VT 05405, USA
| | - Kyoung Hwan Lee
- Division of Cell Biology and Imaging, Department of Radiology, University of Massachusetts Medical School, Worcester, MA 01655, USA
| | - Gina Kuffel
- Department of Public Health Sciences, Loyola University Chicago, Maywood, IL 60153, USA
| | - Michael J Zilliox
- Department of Public Health Sciences, Loyola University Chicago, Maywood, IL 60153, USA
| | - Brian Leei Lin
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, IL 60153, USA
| | - Weikang Ma
- Center for Synchrotron Radiation Research and Instrumentation and Department of Biological Sciences, Illinois Institute of Technology, Chicago, IL 60616, USA
| | - Aaron M Gibson
- Department of Pediatrics, Heart Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, USA
| | - Burns C Blaxall
- Department of Pediatrics, Heart Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, USA
| | - Michelle L Nieman
- Department of Pharmacology and Systems Physiology, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - John N Lorenz
- Department of Pharmacology and Systems Physiology, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Dana M Leichter
- Research Service, Providence VA Medical Center, Providence, RI 02908, USA
| | - Owen P Leary
- Research Service, Providence VA Medical Center, Providence, RI 02908, USA
| | - Paul M L Janssen
- Department of Physiology and Cell Biology, The Ohio State University, Columbus, OH 43210, USA
| | - Pieter P de Tombe
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, IL 60153, USA; Department of Physiology, University of Illinois at Chicago, Chicago 60612, USA; Phymedexp, Université de Montpellier, Inserm, CNRS, Montpellier, France
| | - Richard J Gilbert
- Research Service, Providence VA Medical Center, Providence, RI 02908, USA
| | - Roger Craig
- Division of Cell Biology and Imaging, Department of Radiology, University of Massachusetts Medical School, Worcester, MA 01655, USA
| | - Thomas Irving
- Center for Synchrotron Radiation Research and Instrumentation and Department of Biological Sciences, Illinois Institute of Technology, Chicago, IL 60616, USA
| | - David M Warshaw
- Department of Molecular Physiology and Biophysics, Cardiovascular Research Institute, University of Vermont, Burlington, VT 05405, USA
| | - Sakthivel Sadayappan
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, IL 60153, USA; Heart, Lung and Vascular Institute, Division of Cardiovascular Health and Disease, Department of Internal Medicine, University of Cincinnati, Cincinnati, OH 45267, USA.
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10
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Suay-Corredera C, Pricolo MR, Herrero-Galán E, Velázquez-Carreras D, Sánchez-Ortiz D, García-Giustiniani D, Delgado J, Galano-Frutos JJ, García-Cebollada H, Vilches S, Domínguez F, Molina MS, Barriales-Villa R, Frisso G, Sancho J, Serrano L, García-Pavía P, Monserrat L, Alegre-Cebollada J. Protein haploinsufficiency drivers identify MYBPC3 variants that cause hypertrophic cardiomyopathy. J Biol Chem 2021; 297:100854. [PMID: 34097875 PMCID: PMC8260873 DOI: 10.1016/j.jbc.2021.100854] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Revised: 05/21/2021] [Accepted: 06/03/2021] [Indexed: 02/06/2023] Open
Abstract
Hypertrophic cardiomyopathy (HCM) is the most common inherited cardiac disease. Variants in MYBPC3, the gene encoding cardiac myosin-binding protein C (cMyBP-C), are the leading cause of HCM. However, the pathogenicity status of hundreds of MYBPC3 variants found in patients remains unknown, as a consequence of our incomplete understanding of the pathomechanisms triggered by HCM-causing variants. Here, we examined 44 nontruncating MYBPC3 variants that we classified as HCM-linked or nonpathogenic according to cosegregation and population genetics criteria. We found that around half of the HCM-linked variants showed alterations in RNA splicing or protein stability, both of which can lead to cMyBP-C haploinsufficiency. These protein haploinsufficiency drivers associated with HCM pathogenicity with 100% and 94% specificity, respectively. Furthermore, we uncovered that 11% of nontruncating MYBPC3 variants currently classified as of uncertain significance in ClinVar induced one of these molecular phenotypes. Our strategy, which can be applied to other conditions induced by protein loss of function, supports the idea that cMyBP-C haploinsufficiency is a fundamental pathomechanism in HCM.
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Affiliation(s)
| | - Maria Rosaria Pricolo
- Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain; Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Università di Napoli Federico II, Naples, Italy
| | | | | | | | | | - Javier Delgado
- EMBL/CRG Systems Biology Research Unit, Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Juan José Galano-Frutos
- Departamento de Bioquímica y Biología Molecular y Celular, Facultad de Ciencias, Universidad de Zaragoza, Zaragoza, Spain; Biocomputation and Complex Systems Physics Institute (BIFI). Joint Units BIFI-IQFR (CSIC) and GBs-CSIC, Universidad de Zaragoza, Zaragoza, Spain
| | - Helena García-Cebollada
- Departamento de Bioquímica y Biología Molecular y Celular, Facultad de Ciencias, Universidad de Zaragoza, Zaragoza, Spain; Biocomputation and Complex Systems Physics Institute (BIFI). Joint Units BIFI-IQFR (CSIC) and GBs-CSIC, Universidad de Zaragoza, Zaragoza, Spain
| | - Silvia Vilches
- Heart Failure and Inherited Cardiac Diseases Unit. Department of Cardiology. Hospital Universitario Puerta de Hierro, Madrid, Spain; European Reference Network for Rare and Low Prevalence Complex Diseases of the Heart (ERN GUARD-HEART), Madrid, Spain
| | - Fernando Domínguez
- Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain; Heart Failure and Inherited Cardiac Diseases Unit. Department of Cardiology. Hospital Universitario Puerta de Hierro, Madrid, Spain; European Reference Network for Rare and Low Prevalence Complex Diseases of the Heart (ERN GUARD-HEART), Madrid, Spain; Centro de Investigación Biomédica en Red en Enfermedades Cardiovasculares (CIBERCV), Madrid, Spain
| | - María Sabater Molina
- European Reference Network for Rare and Low Prevalence Complex Diseases of the Heart (ERN GUARD-HEART), Madrid, Spain; Hospital C. Universitario Virgen de la Arrixaca, El Palmar, Murcia, Spain
| | - Roberto Barriales-Villa
- Centro de Investigación Biomédica en Red en Enfermedades Cardiovasculares (CIBERCV), Madrid, Spain; Unidad de Cardiopatías Familiares, Instituto de Investigación Biomédica de A Coruña (INIBIC), Complexo Hospitalario Universitario de A Coruña, Servizo Galego de Saúde (SERGAS), Universidade da Coruña, A Coruña, Spain
| | - Giulia Frisso
- Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Università di Napoli Federico II, Naples, Italy; CEINGE Biotecnologie Avanzate, scarl, Naples, Italy
| | - Javier Sancho
- Departamento de Bioquímica y Biología Molecular y Celular, Facultad de Ciencias, Universidad de Zaragoza, Zaragoza, Spain; Biocomputation and Complex Systems Physics Institute (BIFI). Joint Units BIFI-IQFR (CSIC) and GBs-CSIC, Universidad de Zaragoza, Zaragoza, Spain; Aragon Health Research Institute (IIS Aragón), Zaragoza, Spain
| | - Luis Serrano
- EMBL/CRG Systems Biology Research Unit, Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Barcelona, Spain; Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain; Universitat Pompeu Fabra (UPF), Barcelona, Spain
| | - Pablo García-Pavía
- Heart Failure and Inherited Cardiac Diseases Unit. Department of Cardiology. Hospital Universitario Puerta de Hierro, Madrid, Spain; European Reference Network for Rare and Low Prevalence Complex Diseases of the Heart (ERN GUARD-HEART), Madrid, Spain; Centro de Investigación Biomédica en Red en Enfermedades Cardiovasculares (CIBERCV), Madrid, Spain; Universidad Francisco de Vitoria (UFV), Pozuelo de Alarcón, Madrid, Spain
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11
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Suay-Corredera C, Pricolo MR, Velázquez-Carreras D, Pathak D, Nandwani N, Pimenta-Lopes C, Sánchez-Ortiz D, Urrutia-Irazabal I, Vilches S, Dominguez F, Frisso G, Monserrat L, García-Pavía P, de Sancho D, Spudich JA, Ruppel KM, Herrero-Galán E, Alegre-Cebollada J. Nanomechanical Phenotypes in Cardiac Myosin-Binding Protein C Mutants That Cause Hypertrophic Cardiomyopathy. ACS NANO 2021; 15:10203-10216. [PMID: 34060810 PMCID: PMC8514129 DOI: 10.1021/acsnano.1c02242] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Hypertrophic cardiomyopathy (HCM) is a disease of the myocardium caused by mutations in sarcomeric proteins with mechanical roles, such as the molecular motor myosin. Around half of the HCM-causing genetic variants target contraction modulator cardiac myosin-binding protein C (cMyBP-C), although the underlying pathogenic mechanisms remain unclear since many of these mutations cause no alterations in protein structure and stability. As an alternative pathomechanism, here we have examined whether pathogenic mutations perturb the nanomechanics of cMyBP-C, which would compromise its modulatory mechanical tethers across sliding actomyosin filaments. Using single-molecule atomic force spectroscopy, we have quantified mechanical folding and unfolding transitions in cMyBP-C domains targeted by HCM mutations that do not induce RNA splicing alterations or protein thermodynamic destabilization. Our results show that domains containing mutation R495W are mechanically weaker than wild-type at forces below 40 pN and that R502Q mutant domains fold faster than wild-type. None of these alterations are found in control, nonpathogenic variants, suggesting that nanomechanical phenotypes induced by pathogenic cMyBP-C mutations contribute to HCM development. We propose that mutation-induced nanomechanical alterations may be common in mechanical proteins involved in human pathologies.
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Affiliation(s)
| | - Maria Rosaria Pricolo
- Centro Nacional de Investigaciones Cardiovasculares (CNIC), 28029, Madrid, Spain
- Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Università di Napoli Federico II, 80131, Naples, Italy
| | | | - Divya Pathak
- Department of Biochemistry, Stanford University School of Medicine, Stanford, California 94305, United States
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, California 94305, United States
| | - Neha Nandwani
- Department of Biochemistry, Stanford University School of Medicine, Stanford, California 94305, United States
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, California 94305, United States
| | | | - David Sánchez-Ortiz
- Centro Nacional de Investigaciones Cardiovasculares (CNIC), 28029, Madrid, Spain
| | | | - Silvia Vilches
- Heart Failure and Inherited Cardiac Diseases Unit, Department of Cardiology, Hospital Universitario Puerta de Hierro, 28222, Madrid, Spain
- European Reference Network for Rare and Low Prevalence Complex Diseases of the Heart (ERN GUARD-HEART, http://guardheart.ern-net.eu/), 28222, Madrid, Spain
| | - Fernando Dominguez
- Centro Nacional de Investigaciones Cardiovasculares (CNIC), 28029, Madrid, Spain
- Heart Failure and Inherited Cardiac Diseases Unit, Department of Cardiology, Hospital Universitario Puerta de Hierro, 28222, Madrid, Spain
- European Reference Network for Rare and Low Prevalence Complex Diseases of the Heart (ERN GUARD-HEART, http://guardheart.ern-net.eu/), 28222, Madrid, Spain
- Centro de Investigación Biomédica en Red en Enfermedades Cardiovasculares (CIBERCV), 28029, Madrid, Spain
| | - Giulia Frisso
- Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Università di Napoli Federico II, 80131, Naples, Italy
- CEINGE Biotecnologie Avanzate, scarl, 80145, Naples, Italy
| | | | - Pablo García-Pavía
- Heart Failure and Inherited Cardiac Diseases Unit, Department of Cardiology, Hospital Universitario Puerta de Hierro, 28222, Madrid, Spain
- European Reference Network for Rare and Low Prevalence Complex Diseases of the Heart (ERN GUARD-HEART, http://guardheart.ern-net.eu/), 28222, Madrid, Spain
- Centro de Investigación Biomédica en Red en Enfermedades Cardiovasculares (CIBERCV), 28029, Madrid, Spain
- Universidad Francisco de Vitoria (UFV), 28223, Pozuelo de Alarcón, Madrid, Spain
| | - David de Sancho
- Polimero eta Material Aurreratuak: Fisika, Kimika eta Teknologia, Kimika Fakultatea, Euskal Herriko Unibertsitatea UPV/EHU, 20018, Donostia-San Sebastián, Spain
- Donostia International Physics Center (DIPC), 20018, Donostia-San Sebastián, Spain
| | - James A Spudich
- Department of Biochemistry, Stanford University School of Medicine, Stanford, California 94305, United States
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, California 94305, United States
| | - Kathleen M Ruppel
- Department of Biochemistry, Stanford University School of Medicine, Stanford, California 94305, United States
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, California 94305, United States
| | - Elías Herrero-Galán
- Centro Nacional de Investigaciones Cardiovasculares (CNIC), 28029, Madrid, Spain
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12
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Fazlollahi F, Santini Gonzalez JJ, Repas SJ, Canan BD, Billman GE, Janssen PML. Contraction-relaxation coupling is unaltered by exercise training and infarction in isolated canine myocardium. J Gen Physiol 2021; 153:211978. [PMID: 33847735 PMCID: PMC8047736 DOI: 10.1085/jgp.202012829] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Revised: 02/20/2021] [Accepted: 03/18/2021] [Indexed: 12/28/2022] Open
Abstract
The two main phases of the mammalian cardiac cycle are contraction and relaxation; however, whether there is a connection between them in humans is not well understood. Routine exercise has been shown to improve cardiac function, morphology, and molecular signatures. Likewise, the acute and chronic changes that occur in the heart in response to injury, disease, and stress are well characterized, albeit not fully understood. In this study, we investigated how exercise and myocardial injury affect contraction–relaxation coupling. We retrospectively analyzed the correlation between the maximal speed of contraction and the maximal speed of relaxation of canine myocardium after receiving surgically induced myocardial infarction, followed by either sedentary recovery or exercise training for 10–12 wk. We used isolated right ventricular trabeculae, which were electrically paced at different lengths, frequencies, and with increasing β-adrenoceptor stimulation. In all conditions, contraction and relaxation were linearly correlated, irrespective of injury or training history. Based on these results and the available literature, we posit that contraction–relaxation coupling is a fundamental myocardial property that resides in the structural arrangement of proteins at the level of the sarcomere and that this may be regulated by the actions of cardiac myosin binding protein C (cMyBP-C) on actin and myosin.
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Affiliation(s)
- Farbod Fazlollahi
- Department of Physiology and Cell Biology, College of Medicine, Ohio State University, Columbus, OH
| | - Jorge J Santini Gonzalez
- Department of Physiology and Cell Biology, College of Medicine, Ohio State University, Columbus, OH
| | - Steven J Repas
- Department of Physiology and Cell Biology, College of Medicine, Ohio State University, Columbus, OH
| | - Benjamin D Canan
- Department of Physiology and Cell Biology, College of Medicine, Ohio State University, Columbus, OH
| | - George E Billman
- Department of Physiology and Cell Biology, College of Medicine, Ohio State University, Columbus, OH
| | - Paul M L Janssen
- Department of Physiology and Cell Biology, College of Medicine, Ohio State University, Columbus, OH
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13
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Harris SP. Making waves: A proposed new role for myosin-binding protein C in regulating oscillatory contractions in vertebrate striated muscle. J Gen Physiol 2021; 153:e202012729. [PMID: 33275758 PMCID: PMC7721898 DOI: 10.1085/jgp.202012729] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Myosin-binding protein C (MyBP-C) is a critical regulator of muscle performance that was first identified through its strong binding interactions with myosin, the force-generating protein of muscle. Almost simultaneously with its discovery, MyBP-C was soon found to bind to actin, the physiological catalyst for myosin's activity. However, the two observations posed an apparent paradox, in part because interactions of MyBP-C with myosin were on the thick filament, whereas MyBP-C interactions with actin were on the thin filament. Despite the intervening decades since these initial discoveries, it is only recently that the dual binding modes of MyBP-C are becoming reconciled in models that place MyBP-C at a central position between actin and myosin, where MyBP-C alternately stabilizes a newly discovered super-relaxed state (SRX) of myosin on thick filaments in resting muscle and then prolongs the "on" state of actin on thin filaments in active muscle. Recognition of these dual, alternating functions of MyBP-C reveals how it is central to the regulation of both muscle contraction and relaxation. The purpose of this Viewpoint is to briefly summarize the roles of MyBP-C in binding to myosin and actin and then to highlight a possible new role for MyBP-C in inducing and damping oscillatory waves of contraction and relaxation. Because the contractile waves bear similarity to cycles of contraction and relaxation in insect flight muscles, which evolved for fast, energetically efficient contraction, the ability of MyBP-C to damp so-called spontaneous oscillatory contractions (SPOCs) has broad implications for previously unrecognized regulatory mechanisms in vertebrate striated muscle. While the molecular mechanisms by which MyBP-C can function as a wave maker or a wave breaker are just beginning to be explored, it is likely that MyBP-C dual interactions with both myosin and actin will continue to be important for understanding the new functions of this enigmatic protein.
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14
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Zhao X, Hou C, Xiao T, Xie L, Li Y, Jia J, Zheng J, Zhang Y, Xu M. An interesting Mybpc3 heterozygous mutation associated with bicuspid aortic valve. Transl Pediatr 2020; 9:610-618. [PMID: 33209723 PMCID: PMC7658766 DOI: 10.21037/tp-20-81] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
BACKGROUND Bicuspid aortic valve (BAV) is a common congenital heart defect (0.5-2.0% in the adult), potentially an onset factor of aortic stenosis (AS). Increasing evidence demonstrates that genetic risk factors play a key role in the pathogenesis of BAV, but the genetic basis underlying this cardiac malformation remains poorly understood. METHODS Whole exome sequencing (WES) was utilized to uncover genetic variants associated with BAV. Pathogenicity score and mode of inheritance through bioinformatics tools were undertook to identify the possible disease-causing mutation. RESULTS A heterozygous Ala58Val mutation in Myosin binding protein C (Mybpc3) was identified out of 2,840 variants in an 11-year-old female patient. The proband and her father were confirmed to be heterozygous carriers of 173 C>T hybridization, and her mother was homozygous negative of the mutation as confirmed through Sanger sequencing. Expression of mRNA in the proband and her father, who also carries the mutation, were almost half of proband's mother. Indicating Mybpc3 (p.Ala58Val) mutation affected its expression, and may play crucial roles for heritable BAV. CONCLUSIONS To our knowledge, this is the first time to report Mybpc3 heterozygous variant associated with heritable BAV. The relationship between the location of Mybpc3 mutation and BAV may provide a novel perspective of understanding this disorder.
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Affiliation(s)
- Xiaopei Zhao
- Department of Cardiology, Shanghai Children's Hospital, Shanghai Jiaotong University, Shanghai, China
| | - Cuilan Hou
- Department of Cardiology, Shanghai Children's Hospital, Shanghai Jiaotong University, Shanghai, China.,NHC Key Laboratory of Medical Embryogenesis and Developmental Molecular Biology, Shanghai Key Laboratory of Embryo and Reproduction Engineering, Shanghai, China
| | - Tingting Xiao
- Department of Cardiology, Shanghai Children's Hospital, Shanghai Jiaotong University, Shanghai, China.,NHC Key Laboratory of Medical Embryogenesis and Developmental Molecular Biology, Shanghai Key Laboratory of Embryo and Reproduction Engineering, Shanghai, China
| | - Lijian Xie
- Department of Cardiology, Shanghai Children's Hospital, Shanghai Jiaotong University, Shanghai, China
| | - Yun Li
- Department of Cardiology, Shanghai Children's Hospital, Shanghai Jiaotong University, Shanghai, China
| | - Jia Jia
- Shanghai Center for Bioinformation Technology, Shanghai, China
| | - Junming Zheng
- Department of Cardiology, Shanghai Children's Hospital, Shanghai Jiaotong University, Shanghai, China
| | - Yongwei Zhang
- Department of Cardiology, Shanghai Children's Hospital, Shanghai Jiaotong University, Shanghai, China
| | - Meng Xu
- Department of Cardiology, Shanghai Children's Hospital, Shanghai Jiaotong University, Shanghai, China
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15
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Matsuo T. Usefulness of medium-angle X-ray scattering for structural characterization of flexible proteins studied by computer simulations. Biochem Biophys Res Commun 2020; 525:830-835. [DOI: 10.1016/j.bbrc.2020.02.150] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Accepted: 02/24/2020] [Indexed: 02/06/2023]
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16
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Heling LWHJ, Geeves MA, Kad NM. MyBP-C: one protein to govern them all. J Muscle Res Cell Motil 2020; 41:91-101. [PMID: 31960266 PMCID: PMC7109175 DOI: 10.1007/s10974-019-09567-1] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Accepted: 11/29/2019] [Indexed: 12/19/2022]
Abstract
The heart is an extraordinarily versatile pump, finely tuned to respond to a multitude of demands. Given the heart pumps without rest for decades its efficiency is particularly relevant. Although many proteins in the heart are essential for viability, the non-essential components can attract numerous mutations which can cause disease, possibly through alterations in pumping efficiency. Of these, myosin binding protein C is strongly over-represented with ~ 40% of all known mutations in hypertrophic cardiomyopathy. Therefore, a complete understanding of its molecular function in the cardiac sarcomere is warranted. In this review, we revisit contemporary and classical literature to clarify both the current standing of this fast-moving field and frame future unresolved questions. To date, much effort has been directed at understanding MyBP-C function on either thick or thin filaments. Here we aim to focus questions on how MyBP-C functions at a molecular level in the context of both the thick and thin filaments together. A concept that emerges is MyBP-C acts to govern interactions on two levels; controlling myosin access to the thin filament by sequestration on the thick filament, and controlling the activation state and access of myosin to its binding sites on the thin filament. Such affects are achieved through directed interactions mediated by phosphorylation (of MyBP-C and other sarcomeric components) and calcium.
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Affiliation(s)
- L W H J Heling
- School of Biosciences, University of Kent, Canterbury, CT2 7NH, UK
| | - M A Geeves
- School of Biosciences, University of Kent, Canterbury, CT2 7NH, UK
| | - N M Kad
- School of Biosciences, University of Kent, Canterbury, CT2 7NH, UK.
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17
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Pricolo MR, Herrero-Galán E, Mazzaccara C, Losi MA, Alegre-Cebollada J, Frisso G. Protein Thermodynamic Destabilization in the Assessment of Pathogenicity of a Variant of Uncertain Significance in Cardiac Myosin Binding Protein C. J Cardiovasc Transl Res 2020; 13:867-877. [PMID: 32034629 DOI: 10.1007/s12265-020-09959-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Accepted: 01/20/2020] [Indexed: 12/29/2022]
Abstract
In the era of next generation sequencing (NGS), genetic testing for inherited disorders identifies an ever-increasing number of variants whose pathogenicity remains unclear. These variants of uncertain significance (VUS) limit the reach of genetic testing in clinical practice. The VUS for hypertrophic cardiomyopathy (HCM), the most common familial heart disease, constitute over 60% of entries for missense variants shown in ClinVar database. We have studied a novel VUS (c.1809T>G-p.I603M) in the most frequently mutated gene in HCM, MYBPC3, which codes for cardiac myosin-binding protein C (cMyBPC). Our determinations of pathogenicity integrate bioinformatics evaluation and functional studies of RNA splicing and protein thermodynamic stability. In silico prediction and mRNA analysis indicated no alteration of RNA splicing induced by the variant. At the protein level, the p.I603M mutation maps to the C4 domain of cMyBPC. Although the mutation does not perturb much the overall structure of the C4 domain, the stability of C4 I603M is severely compromised as detected by circular dichroism and differential scanning calorimetry experiments. Taking into account the highly destabilizing effect of the mutation in the structure of C4, we propose reclassification of variant p.I603M as likely pathogenic. Looking into the future, the workflow described here can be used to refine the assignment of pathogenicity of variants of uncertain significance in MYBPC3.
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Affiliation(s)
- Maria Rosaria Pricolo
- Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Madrid, Spain. .,Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Università Federico II, Naples, Italy.
| | - Elías Herrero-Galán
- Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Madrid, Spain
| | - Cristina Mazzaccara
- Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Università Federico II, Naples, Italy.,CEINGE Biotecnologie Avanzate s.c. a r.l., Naples, Italy
| | - Maria Angela Losi
- Dipartimento di Scienze Biomediche Avanzate, Università Federico II, Naples, Italy
| | | | - Giulia Frisso
- Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Università Federico II, Naples, Italy.,CEINGE Biotecnologie Avanzate s.c. a r.l., Naples, Italy
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18
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Burghardt TP. Demographic model for inheritable cardiac disease. Arch Biochem Biophys 2019; 672:108056. [PMID: 31356777 DOI: 10.1016/j.abb.2019.07.021] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Revised: 07/24/2019] [Accepted: 07/25/2019] [Indexed: 11/15/2022]
Abstract
The cardiac muscle proteins, generating and regulating energy transduction during a heartbeat, assemble in the sarcomere into a cyclical machine repetitively translating actin relative to myosin filaments. Myosin is the motor transducing ATP free energy into actin movement against resisting force. Cardiac myosin binding protein C (mybpc3) regulates shortening velocity probably by transient N-terminus binding to actin while its C-terminus strongly binds the myosin filament. Inheritable heart disease associated mutants frequently modify these proteins involving them in disease mechanisms. Nonsynonymous single nucleotide polymorphisms (SNPs) cause single residue substitutions with independent characteristics (sequence location, residue substitution, human demographic, and allele frequency) hypothesized to decide dependent phenotype and pathogenicity characteristics in a feed-forward neural network model. Trial models train and validate on a dynamic worldwide SNP database for cardiac muscle proteins then predict phenotype and pathogenicity for any single residue substitution in myosin, mybpc3, or actin. A separate Bayesian model formulates conditional probabilities for phenotype or pathogenicity given independent SNP characteristics. Neural/Bayes forecasting tests SNP pathogenicity vs (in)dependent SNP characteristics to assess individualized disease risk and in particular to elucidate gender and human subpopulation bias in disease. Evident subpopulation bias in myosin SNP pathogenicities imply myosin normally engages multiple sarcomere proteins functionally. Consistent with this observation, mybpc3 forms a third actomyosin interaction competing with myosin essential light chain N-terminus suggesting a novel strain-dependent mechanism adapting myosin force-velocity to load dynamics. The working models, and the integral myosin/mybpc3 motor concept, portends the wider considerations involved in understanding heart disease as a systemic maladaptation.
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Affiliation(s)
- Thomas P Burghardt
- Department of Biochemistry and Molecular Biology and Physiology and Biomedical Engineering, 200 First St. SW, Mayo Clinic Rochester, Rochester, MN, 55905, USA.
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19
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Spudich JA. Three perspectives on the molecular basis of hypercontractility caused by hypertrophic cardiomyopathy mutations. Pflugers Arch 2019; 471:701-717. [PMID: 30767072 PMCID: PMC6475635 DOI: 10.1007/s00424-019-02259-2] [Citation(s) in RCA: 104] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Revised: 01/11/2019] [Accepted: 01/20/2019] [Indexed: 01/10/2023]
Abstract
Several lines of evidence suggest that the primary effect of hypertrophic cardiomyopathy mutations in human β-cardiac myosin is hypercontractility of the heart, which leads to subsequent hypertrophy, fibrosis, and myofilament disarray. Here, I describe three perspectives on the molecular basis of this hypercontractility. The first is that hypercontractility results from changes in the fundamental parameters of the actin-activated β-cardiac myosin chemo-mechanical ATPase cycle. The second considers that hypercontractility results from an increase in the number of functionally accessible heads in the sarcomere for interaction with actin. The final and third perspective is that load dependence of contractility is affected by cardiomyopathy mutations and small-molecule effectors in a manner that changes the power output of cardiac contraction. Experimental approaches associated with each perspective are described along with concepts of therapeutic approaches that could prove valuable in treating hypertrophic cardiomyopathy.
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Affiliation(s)
- James A Spudich
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA, 94305, USA.
- Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA, 94305, USA.
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20
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Role of intrinsic disorder in muscle sarcomeres. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2019; 166:311-340. [PMID: 31521234 DOI: 10.1016/bs.pmbts.2019.03.014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The role and utility of intrinsically disordered regions (IDRs) is reviewed for two groups of sarcomeric proteins, such as members of tropomodulin/leiomodin (Tmod/Lmod) protein homology group and myosin binding protein C (MyBP-C). These two types of sarcomeric proteins represent very different but strongly interdependent functions, being responsible for maintaining structure and operation of the muscle sarcomere. The role of IDRs in the formation of complexes between thin filaments and Tmods/Lmods is discussed within the framework of current understanding of the thin filament length regulation. For MyBP-C, the function of IDRs is discussed in the context of MYBP-C-dependent sarcomere contraction and actomyosin activation.
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21
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Robinett JC, Hanft LM, Geist J, Kontrogianni-Konstantopoulos A, McDonald KS. Regulation of myofilament force and loaded shortening by skeletal myosin binding protein C. J Gen Physiol 2019; 151:645-659. [PMID: 30705121 PMCID: PMC6504288 DOI: 10.1085/jgp.201812200] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Accepted: 01/11/2019] [Indexed: 12/28/2022] Open
Abstract
Myosin binding protein C (MyBP-C) is thought to regulate the contraction of skeletal muscle. Robinett et al. show that phosphorylation of slow skeletal MyBP-C modulates contraction by recruiting cross-bridges, modifying cross-bridge kinetics, and altering internal drag forces in the C-zone. Myosin binding protein C (MyBP-C) is a 125–140-kD protein located in the C-zone of each half-thick filament. It is thought to be an important regulator of contraction, but its precise role is unclear. Here we investigate mechanisms by which skeletal MyBP-C regulates myofilament function using rat permeabilized skeletal muscle fibers. We mount either slow-twitch or fast-twitch skeletal muscle fibers between a force transducer and motor, use Ca2+ to activate a range of forces, and measure contractile properties including transient force overshoot, rate of force development, and loaded sarcomere shortening. The transient force overshoot is greater in slow-twitch than fast-twitch fibers at all Ca2+ activation levels. In slow-twitch fibers, protein kinase A (PKA) treatment (a) augments phosphorylation of slow skeletal MyBP-C (sMyBP-C), (b) doubles the magnitude of the relative transient force overshoot at low Ca2+ activation levels, and (c) increases force development rates at all Ca2+ activation levels. We also investigate the role that phosphorylated and dephosphorylated sMyBP-C plays in loaded sarcomere shortening. We test the hypothesis that MyBP-C acts as a brake to filament sliding within the myofilament lattice by measuring sarcomere shortening as thin filaments traverse into the C-zone during lightly loaded slow-twitch fiber contractions. Before PKA treatment, shortening velocity decelerates as sarcomeres traverse from ∼3.10 to ∼3.00 µm. After PKA treatment, sarcomeres shorten a greater distance and exhibit less deceleration during similar force clamps. After sMyBP-C dephosphorylation, sarcomere length traces display a brief recoil (i.e., “bump”) that initiates at ∼3.06 µm during loaded shortening. Interestingly, the timing of the bump shifts with changes in load but manifests at the same sarcomere length. Our results suggest that sMyBP-C and its phosphorylation state regulate sarcomere contraction by a combination of cross-bridge recruitment, modification of cross-bridge cycling kinetics, and alteration of drag forces that originate in the C-zone.
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Affiliation(s)
- Joel C Robinett
- Department of Medical Pharmacology and Physiology, School of Medicine, University of Missouri, Columbia, MO
| | - Laurin M Hanft
- Department of Medical Pharmacology and Physiology, School of Medicine, University of Missouri, Columbia, MO
| | - Janelle Geist
- Department of Biochemistry and Molecular Biology, School of Medicine, University of Maryland, Baltimore, MD
| | | | - Kerry S McDonald
- Department of Medical Pharmacology and Physiology, School of Medicine, University of Missouri, Columbia, MO
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22
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Tiberti M, Lechner BD, Fornili A. Binding Pockets in Proteins Induced by Mechanical Stress. J Chem Theory Comput 2019; 15:1-6. [PMID: 30525608 DOI: 10.1021/acs.jctc.8b00755] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
We report the first observation of a pocket that opens as a result of a mechanical force applied to an Ig-like domain from the cardiac muscle. This previously unseen mechanism of pocket formation is revealed by molecular dynamics simulations under force. Preliminary investigations show that this "mechano-pocket" is potentially druggable and could be found in other domains from the same fold family, suggesting the existence of a general mechanism of pocket formation under mechanical stress.
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Affiliation(s)
- Matteo Tiberti
- School of Biological and Chemical Sciences , Queen Mary University of London , London E1 4NS , United Kingdom
| | - Bob-Dan Lechner
- School of Biological and Chemical Sciences , Queen Mary University of London , London E1 4NS , United Kingdom
| | - Arianna Fornili
- School of Biological and Chemical Sciences , Queen Mary University of London , London E1 4NS , United Kingdom.,The Thomas Young Centre for Theory and Simulation of Materials , London , United Kingdom
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23
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Giles J, Patel JR, Miller A, Iverson E, Fitzsimons D, Moss RL. Recovery of left ventricular function following in vivo reexpression of cardiac myosin binding protein C. J Gen Physiol 2019; 151:77-89. [PMID: 30573635 PMCID: PMC6314388 DOI: 10.1085/jgp.201812238] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Accepted: 11/27/2018] [Indexed: 01/26/2023] Open
Abstract
The loss of cardiac myosin binding protein C (cMyBP-C) results in left ventricular dilation, cardiac hypertrophy, and impaired ventricular function in both constitutive and conditional cMyBP-C knockout (MYBPC3 null) mice. It remains unclear whether the structural and functional phenotypes expressed in the MYBPC3 null mouse are reversible, which is an important question, since reduced expression of cMyBP-C is an important cause of hypertrophic cardiomyopathy in humans. To investigate this question, we generated a cardiac-specific transgenic mouse model using a Tet-Off inducible system to permit the controlled expression of WT cMyBP-C on the MYBPC3 null background. Functional Tet-Off mice expressing WT cMyBP-C (FT-WT) were generated by crossing tetracycline transactivator mice with responder mice carrying the WT cMyBP-C transgene. Prior to dietary doxycycline administration, cMyBP-C was expressed at normal levels in FT-WT myocardium, which exhibited similar levels of steady-state force and in vivo left ventricular function as WT mice. Introduction of dietary doxycycline for four weeks resulted in a partial knockdown of cMyBP-C expression and commensurate impairment of systolic and diastolic function to levels approaching those observed in MYBPC 3 null mice. Subsequent withdrawal of doxycycline from the diet resulted in the reexpression of cMyBP-C to levels comparable to those observed in WT mice, along with near-complete recovery of in vivo ventricular function. These results show that the cardiac phenotypes associated with MYBPC3 null mice are reversible. Our work also validates the use of the Tet-Off inducible system as a means to study the mechanisms underlying hypertrophic cardiomyopathy.
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Affiliation(s)
- Jasmine Giles
- Department of Cell and Regenerative Biology, University of Wisconsin School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI
| | - Jitandrakumar R Patel
- Department of Cell and Regenerative Biology, University of Wisconsin School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI
- University of Wisconsin Cardiovascular Research Center, University of Wisconsin School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI
| | - Adam Miller
- Department of Cell and Regenerative Biology, University of Wisconsin School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI
| | - Elizabeth Iverson
- Department of Cell and Regenerative Biology, University of Wisconsin School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI
| | - Daniel Fitzsimons
- Department of Cell and Regenerative Biology, University of Wisconsin School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI
- University of Wisconsin Cardiovascular Research Center, University of Wisconsin School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI
| | - Richard L Moss
- Department of Cell and Regenerative Biology, University of Wisconsin School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI
- University of Wisconsin Cardiovascular Research Center, University of Wisconsin School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI
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24
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Doh CY, Li J, Mamidi R, Stelzer JE. The HCM-causing Y235S cMyBPC mutation accelerates contractile function by altering C1 domain structure. Biochim Biophys Acta Mol Basis Dis 2019; 1865:661-677. [PMID: 30611859 DOI: 10.1016/j.bbadis.2019.01.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Revised: 12/18/2018] [Accepted: 01/02/2019] [Indexed: 12/20/2022]
Abstract
Mutations in cardiac myosin binding protein C (cMyBPC) are a major cause of hypertrophic cardiomyopathy (HCM). In particular, a single amino acid substitution of tyrosine to serine at residue 237 in humans (residue 235 in mice) has been linked to HCM with strong disease association. Although cMyBPC truncations, deletions and insertions, and frame shift mutations have been studied, relatively little is known about the functional consequences of missense mutations in cMyBPC. In this study, we characterized the functional and structural effects of the HCM-causing Y235S mutation by performing mechanical experiments and molecular dynamics simulations (MDS). cMyBPC null mouse myocardium was virally transfected with wild-type (WT) or Y235S cMyBPC (KOY235S). We found that Y235S cMyBPC was properly expressed and incorporated into the cardiac sarcomere, suggesting that the mechanism of disease of the Y235S mutation is not haploinsufficiency or poison peptides. Mechanical experiments in detergent-skinned myocardium isolated from KOY235S hearts revealed hypercontractile behavior compared to KOWT hearts, evidenced by accelerated cross-bridge kinetics and increased Ca2+ sensitivity of force generation. In addition, MDS revealed that the Y235S mutation causes alterations in important intramolecular interactions, surface conformations, and electrostatic potential of the C1 domain of cMyBPC. Our combined in vitro and in silico data suggest that the Y235S mutation directly disrupts internal and surface properties of the C1 domain of cMyBPC, which potentially alters its ligand-binding interactions. These molecular changes may underlie the mechanism for hypercontractile cross-bridge behavior, which ultimately results in the development of cardiac hypertrophy and in vivo cardiac dysfunction.
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Affiliation(s)
- Chang Yoon Doh
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Jiayang Li
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Ranganath Mamidi
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Julian E Stelzer
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH, USA.
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25
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Yang KC, Breitbart A, De Lange WJ, Hofsteen P, Futakuchi-Tsuchida A, Xu J, Schopf C, Razumova MV, Jiao A, Boucek R, Pabon L, Reinecke H, Kim DH, Ralphe JC, Regnier M, Murry CE. Novel Adult-Onset Systolic Cardiomyopathy Due to MYH7 E848G Mutation in Patient-Derived Induced Pluripotent Stem Cells. JACC Basic Transl Sci 2018; 3:728-740. [PMID: 30623132 PMCID: PMC6314962 DOI: 10.1016/j.jacbts.2018.08.008] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Revised: 08/16/2018] [Accepted: 08/21/2018] [Indexed: 12/15/2022]
Abstract
A novel myosin heavy chain 7 mutation (E848G) identified in a familial cardiomyopathy was studied in patient-specific induced pluripotent stem cell-derived cardiomyocytes. The cardiomyopathic human induced pluripotent stem cell-derived cardiomyocytes exhibited reduced contractile function as single cells and engineered heart tissues, and genome-edited isogenic cells confirmed the pathogenic nature of the E848G mutation. Reduced contractility may result from impaired interaction between myosin heavy chain 7 and cardiac myosin binding protein C.
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Key Words
- Ad-GFP, green fluorescent protein–encoding adenovirus
- DCM, dilated cardiomyopathy
- EHT, engineered heart tissue
- FCM, familial cardiomyopathy
- HCM, hypertrophic cardiomyopathy
- KO, knockout
- MOI, multiplicity of infections
- MYH, myosin heavy chain
- WT, wild-type
- cMyBP-C, cardiac myosin-binding protein C
- disease-modeling
- engineered heart tissue
- genetic cardiomyopathy
- hiPSC-CM, human induced pluripotent stem cell–derived cardiomyocyte
- iPSC-CM, induced pluripotent stem cell–derived cardiomyocyte
- induced pluripotent stem cells
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Affiliation(s)
- Kai-Chun Yang
- Department of Medicine/Cardiology, University of Washington, Seattle, Washington
- Center for Cardiovascular Biology, University of Washington, Seattle, Washington
- Department of Pathology, University of Washington, Seattle, Washington
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, Washington
| | - Astrid Breitbart
- Center for Cardiovascular Biology, University of Washington, Seattle, Washington
- Department of Pathology, University of Washington, Seattle, Washington
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, Washington
| | - Willem J. De Lange
- Department of Pediatrics, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
| | - Peter Hofsteen
- Center for Cardiovascular Biology, University of Washington, Seattle, Washington
- Department of Pathology, University of Washington, Seattle, Washington
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, Washington
| | - Akiko Futakuchi-Tsuchida
- Center for Cardiovascular Biology, University of Washington, Seattle, Washington
- Department of Pathology, University of Washington, Seattle, Washington
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, Washington
| | - Joy Xu
- Center for Cardiovascular Biology, University of Washington, Seattle, Washington
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, Washington
- Department of Bioengineering, University of Washington, Seattle, Washington
| | - Cody Schopf
- Center for Cardiovascular Biology, University of Washington, Seattle, Washington
- Department of Pathology, University of Washington, Seattle, Washington
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, Washington
| | - Maria V. Razumova
- Center for Cardiovascular Biology, University of Washington, Seattle, Washington
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, Washington
- Department of Bioengineering, University of Washington, Seattle, Washington
| | - Alex Jiao
- Center for Cardiovascular Biology, University of Washington, Seattle, Washington
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, Washington
- Department of Bioengineering, University of Washington, Seattle, Washington
| | - Robert Boucek
- Department of Pediatrics, Seattle’s Children’s Hospital and the University of Washington, Seattle, Washington
| | - Lil Pabon
- Center for Cardiovascular Biology, University of Washington, Seattle, Washington
- Department of Pathology, University of Washington, Seattle, Washington
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, Washington
| | - Hans Reinecke
- Center for Cardiovascular Biology, University of Washington, Seattle, Washington
- Department of Pathology, University of Washington, Seattle, Washington
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, Washington
| | - Deok-Ho Kim
- Center for Cardiovascular Biology, University of Washington, Seattle, Washington
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, Washington
- Department of Bioengineering, University of Washington, Seattle, Washington
| | - J. Carter Ralphe
- Department of Pediatrics, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
| | - Michael Regnier
- Center for Cardiovascular Biology, University of Washington, Seattle, Washington
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, Washington
- Department of Bioengineering, University of Washington, Seattle, Washington
| | - Charles E. Murry
- Department of Medicine/Cardiology, University of Washington, Seattle, Washington
- Center for Cardiovascular Biology, University of Washington, Seattle, Washington
- Department of Pathology, University of Washington, Seattle, Washington
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, Washington
- Department of Bioengineering, University of Washington, Seattle, Washington
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26
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Bunch TA, Lepak VC, Kanassatega RS, Colson BA. N-terminal extension in cardiac myosin-binding protein C regulates myofilament binding. J Mol Cell Cardiol 2018; 125:140-148. [PMID: 30359561 DOI: 10.1016/j.yjmcc.2018.10.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Revised: 08/22/2018] [Accepted: 10/10/2018] [Indexed: 10/28/2022]
Abstract
RATIONALE Mutations in the gene encoding the sarcomeric protein cardiac myosin-binding protein C (cMyBP-C) are a leading cause of hypertrophic cardiomyopathy (HCM). Mouse models targeting cMyBP-C and use of recombinant proteins have been effective in studying its roles in contractile function and disease. Surprisingly, while the N-terminus of cMyBP-C is important to regulate myofilament binding and contains many HCM mutations, an incorrect sequence, lacking the N-terminal 8 amino acids has been used in many studies. OBJECTIVES To determine the N-terminal cMyBP-C sequences in ventricles and investigate the roles of species-specific differences in cMyBP-C on myofilament binding. METHODS AND RESULTS We determined cMyBP-C sequences in mouse and human by inspecting available sequence databases. N-terminal differences were confirmed using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Cosedimentation assays with actin or myosin were used to examine binding in mouse, human and chimeric fusion proteins of cMyBP-C. Time-resolved FRET (TR-FRET) with site-directed probes on cMyBP-C was employed to measure structural dynamics. LC-MS/MS supported the sequencing data that mouse cMyBP-C contains an eight-residue N-terminal extension (NTE) not found in human. Cosedimentation assays revealed that cardiac myosin binding was strongly influenced by the presence of the NTE, which reduced binding by 60%. 75% more human C0-C2 than mouse bound to myosin. Actin binding of mouse C0-C2 was not affected by the NTE. 50% more human C0-C2 than mouse bound to actin. TR-FRET indicates that the NTE did not significantly affect structural dynamics across domains C0 and C1. CONCLUSIONS Our functional results are consistent with the idea that cardiac myosin binding of N-terminal cMyBP-C is reduced in the mouse protein due to the presence of the NTE, which is proposed to interfere with myosin regulatory light chain (RLC) binding. The NTE is a critical component of mouse cMyBP-C, and should be considered in extrapolation of studies to cMyBP-C and HCM mechanisms in human.
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Affiliation(s)
- Thomas A Bunch
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85724, United States
| | - Victoria C Lepak
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85724, United States
| | - Rhye-Samuel Kanassatega
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85724, United States
| | - Brett A Colson
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85724, United States.
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27
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McNamara JW, Sadayappan S. Skeletal myosin binding protein-C: An increasingly important regulator of striated muscle physiology. Arch Biochem Biophys 2018; 660:121-128. [PMID: 30339776 DOI: 10.1016/j.abb.2018.10.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Revised: 10/07/2018] [Accepted: 10/11/2018] [Indexed: 12/22/2022]
Abstract
The Myosin Binding Protein-C (MyBP-C) family is a group of sarcomeric proteins important for striated muscle structure and function. Comprising approximately 2% of the myofilament mass, MyBP-C has important roles in both contraction and relaxation. Three paralogs of MyBP-C are encoded by separate genes with distinct expression profiles in striated muscle. In mammals, cardiac MyBP-C is limited to the heart, and it is the most extensively studied owing to its involvement in cardiomyopathies. However, the roles of two skeletal paralogs, slow and fast, in muscle biology remain poorly characterized. Nonetheless, both have been recently implicated in the development of skeletal myopathies. This calls for a better understanding of their function in the pathophysiology of distal arthrogryposis. This review characterizes MyBP-C as a whole and points out knowledge gaps that still remain with respect to skeletal MyBP-C.
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Affiliation(s)
- James W McNamara
- Heart, Lung and Vascular Institute, Department of Internal Medicine, Division of Cardiovascular Health and Disease, University of Cincinnati, Cincinnati, OH 45236, USA
| | - Sakthivel Sadayappan
- Heart, Lung and Vascular Institute, Department of Internal Medicine, Division of Cardiovascular Health and Disease, University of Cincinnati, Cincinnati, OH 45236, USA.
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28
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Contractility of Airway Smooth Muscle Cell in Response to Zinc Oxide Nanoparticles by Traction Force Microscopy. Ann Biomed Eng 2018; 46:2000-2011. [PMID: 30051243 DOI: 10.1007/s10439-018-2098-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Accepted: 07/17/2018] [Indexed: 12/29/2022]
Abstract
Zinc oxide nanoparticles (ZnO-NPs) have been widely used in engineering and biomedicine. However, their adverse pathological effects and mechanisms, especially the biomechanical effects on respiratory system where airway smooth muscle cell (ASMC) contractility regulates the airway response and lung function, are not fully understood. Herein, we used traction force microscopy (TFM) method to investigate whether ZnO-NPs of different concentrations (0.1-10 μg/mL) can alter ASMC contractility (basal and agonist-stimulated) after a short-term exposure and the potential mechanisms. We found that ZnO-NPs exposure led to a decrease of ASMC viability in a dose-dependent manner. Notably, basal contractility was enhanced when the concentration of ZnO-NPs was less than 0.1 μg/mL and decreased afterwards, while KCl-stimulated contractility was reduced in all cases of ZnO-NPs treated groups. Cytoskeleton structure was also found to be significantly altered in ASMC with the stimulation of ZnO-NPs. More importantly, it seems that ZnO-NPs with low concentration (< 0.1 μg/mL) would change ASMC contractility without any apparent cytotoxicity through disruption of the microtubule assembly. Moreover, our results also emerged that ASMC contractility responses were regulated by clathrin-mediated endocytosis and cytoskeleton remodeling. Together, these findings indicate the susceptibility of cell mechanics to NPs exposure, suggesting that cell mechanical testing will contribute to uncover the pathological mechanisms of NPs in respiratory diseases.
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29
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Neural/Bayes network predictor for inheritable cardiac disease pathogenicity and phenotype. J Mol Cell Cardiol 2018; 119:19-27. [PMID: 29654880 DOI: 10.1016/j.yjmcc.2018.04.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/27/2017] [Revised: 04/03/2018] [Accepted: 04/09/2018] [Indexed: 11/23/2022]
Abstract
The cardiac muscle sarcomere contains multiple proteins contributing to contraction energy transduction and its regulation during a heartbeat. Inheritable heart disease mutants affect most of them but none more frequently than the ventricular myosin motor and cardiac myosin binding protein c (mybpc3). These co-localizing proteins have mybpc3 playing a regulatory role to the energy transducing motor. Residue substitution and functional domain assignment of each mutation in the protein sequence decides, under the direction of a sensible disease model, phenotype and pathogenicity. The unknown model mechanism is decided here using a method combing neural and Bayes networks. Missense single nucleotide polymorphisms (SNPs) are clues for the disease mechanism summarized in an extensive database collecting mutant sequence location and residue substitution as independent variables that imply the dependent disease phenotype and pathogenicity characteristics in 4 dimensional data points (4ddps). The SNP database contains entries with the majority having one or both dependent data entries unfulfilled. A neural network relating causes (mutant residue location and substitution) and effects (phenotype and pathogenicity) is trained, validated, and optimized using fulfilled 4ddps. It then predicts unfulfilled 4ddps providing the implicit disease model. A discrete Bayes network interprets fulfilled and predicted 4ddps with conditional probabilities for phenotype and pathogenicity given mutation location and residue substitution thus relating the neural network implicit model to explicit features of the motor and mybpc3 sequence and structural domains. Neural/Bayes network forecasting automates disease mechanism modeling by leveraging the world wide human missense SNP database that is in place and expanding.
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30
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Wang L, Geist J, Grogan A, Hu LYR, Kontrogianni-Konstantopoulos A. Thick Filament Protein Network, Functions, and Disease Association. Compr Physiol 2018; 8:631-709. [PMID: 29687901 PMCID: PMC6404781 DOI: 10.1002/cphy.c170023] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Sarcomeres consist of highly ordered arrays of thick myosin and thin actin filaments along with accessory proteins. Thick filaments occupy the center of sarcomeres where they partially overlap with thin filaments. The sliding of thick filaments past thin filaments is a highly regulated process that occurs in an ATP-dependent manner driving muscle contraction. In addition to myosin that makes up the backbone of the thick filament, four other proteins which are intimately bound to the thick filament, myosin binding protein-C, titin, myomesin, and obscurin play important structural and regulatory roles. Consistent with this, mutations in the respective genes have been associated with idiopathic and congenital forms of skeletal and cardiac myopathies. In this review, we aim to summarize our current knowledge on the molecular structure, subcellular localization, interacting partners, function, modulation via posttranslational modifications, and disease involvement of these five major proteins that comprise the thick filament of striated muscle cells. © 2018 American Physiological Society. Compr Physiol 8:631-709, 2018.
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Affiliation(s)
- Li Wang
- Department of Biochemistry and Molecular Biology, University of Maryland, Baltimore, Maryland, USA
| | - Janelle Geist
- Department of Biochemistry and Molecular Biology, University of Maryland, Baltimore, Maryland, USA
| | - Alyssa Grogan
- Department of Biochemistry and Molecular Biology, University of Maryland, Baltimore, Maryland, USA
| | - Li-Yen R. Hu
- Department of Biochemistry and Molecular Biology, University of Maryland, Baltimore, Maryland, USA
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31
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Smelter DF, de Lange WJ, Cai W, Ge Y, Ralphe JC. The HCM-linked W792R mutation in cardiac myosin-binding protein C reduces C6 FnIII domain stability. Am J Physiol Heart Circ Physiol 2018; 314:H1179-H1191. [PMID: 29451820 DOI: 10.1152/ajpheart.00686.2017] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Cardiac myosin-binding protein C (cMyBP-C) is a functional sarcomeric protein that regulates contractility in response to contractile demand, and many mutations in cMyBP-C lead to hypertrophic cardiomyopathy (HCM). To gain insight into the effects of disease-causing cMyBP-C missense mutations on contractile function, we expressed the pathogenic W792R mutation (substitution of a highly conserved tryptophan residue by an arginine residue at position 792) in mouse cardiomyocytes lacking endogenous cMyBP-C and studied the functional effects using three-dimensional engineered cardiac tissue constructs (mECTs). Based on complete conservation of tryptophan at this location in fibronectin type II (FnIII) domains, we hypothesized that the W792R mutation affects folding of the C6 FnIII domain, destabilizing the mutant protein. Adenoviral transduction of wild-type (WT) and W792R cDNA achieved equivalent mRNA transcript abundance, but not equivalent protein levels, with W792R compared with WT controls. mECTs expressing W792R demonstrated abnormal contractile kinetics compared with WT mECTs that were nearly identical to cMyBP-C-deficient mECTs. We studied whether common pathways of protein degradation were responsible for the rapid degradation of W792R cMyBP-C. Inhibition of both ubiquitin-proteasome and lysosomal degradation pathways failed to increase full-length mutant protein abundance to WT equivalence, suggesting rapid cytosolic degradation. Bacterial expression of WT and W792R protein fragments demonstrated decreased mutant stability with altered thermal denaturation and increased susceptibility to trypsin digestion. These data suggest that the W792R mutation destabilizes the C6 FnIII domain of cMyBP-C, resulting in decreased full-length protein expression. This study highlights the vulnerability of FnIII-like domains to mutations that alter domain stability and further indicates that missense mutations in cMyBP-C can cause disease through a mechanism of haploinsufficiency. NEW & NOTEWORTHY This study is one of the first to describe a disease mechanism for a missense mutation in cardiac myosin-binding protein C linked to hypertrophic cardiomyopathy. The mutation decreases stability of the fibronectin type III domain and results in substantially reduced mutant protein expression dissonant to transcript abundance.
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Affiliation(s)
- Dan F Smelter
- Department of Pediatrics, University of Wisconsin-Madison , Madison, Wisconsin
| | - Willem J de Lange
- Department of Pediatrics, University of Wisconsin-Madison , Madison, Wisconsin
| | - Wenxuan Cai
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison , Madison, Wisconsin.,Molecular and Cellular Pharmacology Program, University of Wisconsin-Madison , Madison, Wisconsin
| | - Ying Ge
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison , Madison, Wisconsin.,Human Proteomics Program, University of Wisconsin-Madison , Madison, Wisconsin.,Department of Chemistry, School of Medicine and Public Health, University of Wisconsin-Madison , Madison, Wisconsin
| | - J Carter Ralphe
- Department of Pediatrics, University of Wisconsin-Madison , Madison, Wisconsin
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32
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Trivedi DV, Adhikari AS, Sarkar SS, Ruppel KM, Spudich JA. Hypertrophic cardiomyopathy and the myosin mesa: viewing an old disease in a new light. Biophys Rev 2017; 10:27-48. [PMID: 28717924 PMCID: PMC5803174 DOI: 10.1007/s12551-017-0274-6] [Citation(s) in RCA: 105] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2017] [Accepted: 06/12/2017] [Indexed: 12/15/2022] Open
Abstract
The sarcomere is an exquisitely designed apparatus that is capable of generating force, which in the case of the heart results in the pumping of blood throughout the body. At the molecular level, an ATP-dependent interaction of myosin with actin drives the contraction and force generation of the sarcomere. Over the past six decades, work on muscle has yielded tremendous insights into the workings of the sarcomeric system. We now stand on the cusp where the acquired knowledge of how the sarcomere contracts and how that contraction is regulated can be extended to an understanding of the molecular mechanisms of sarcomeric diseases, such as hypertrophic cardiomyopathy (HCM). In this review we present a picture that combines current knowledge of the myosin mesa, the sequestered state of myosin heads on the thick filament, known as the interacting-heads motif (IHM), their possible interaction with myosin binding protein C (MyBP-C) and how these interactions can be abrogated leading to hyper-contractility, a key clinical manifestation of HCM. We discuss the structural and functional basis of the IHM state of the myosin heads and identify HCM-causing mutations that can directly impact the equilibrium between the 'on state' of the myosin heads (the open state) and the IHM 'off state'. We also hypothesize a role of MyBP-C in helping to maintain myosin heads in the IHM state on the thick filament, allowing release in a graded manner upon adrenergic stimulation. By viewing clinical hyper-contractility as the result of the destabilization of the IHM state, our aim is to view an old disease in a new light.
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Affiliation(s)
- Darshan V Trivedi
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA, 94305, USA
| | - Arjun S Adhikari
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA, 94305, USA
| | - Saswata S Sarkar
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA, 94305, USA
| | - Kathleen M Ruppel
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA, 94305, USA. .,Department of Pediatrics (Cardiology), Stanford University School of Medicine, Stanford, CA, 94305, USA.
| | - James A Spudich
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA, 94305, USA.
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33
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Kensler RW, Craig R, Moss RL. Phosphorylation of cardiac myosin binding protein C releases myosin heads from the surface of cardiac thick filaments. Proc Natl Acad Sci U S A 2017; 114:E1355-E1364. [PMID: 28167762 PMCID: PMC5338423 DOI: 10.1073/pnas.1614020114] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Cardiac myosin binding protein C (cMyBP-C) has a key regulatory role in cardiac contraction, but the mechanism by which changes in phosphorylation of cMyBP-C accelerate cross-bridge kinetics remains unknown. In this study, we isolated thick filaments from the hearts of mice in which the three serine residues (Ser273, Ser282, and Ser302) that are phosphorylated by protein kinase A in the m-domain of cMyBP-C were replaced by either alanine or aspartic acid, mimicking the fully nonphosphorylated and the fully phosphorylated state of cMyBP-C, respectively. We found that thick filaments from the cMyBP-C phospho-deficient hearts had highly ordered cross-bridge arrays, whereas the filaments from the cMyBP-C phospho-mimetic hearts showed a strong tendency toward disorder. Our results support the hypothesis that dephosphorylation of cMyBP-C promotes or stabilizes the relaxed/superrelaxed quasi-helical ordering of the myosin heads on the filament surface, whereas phosphorylation weakens this stabilization and binding of the heads to the backbone. Such structural changes would modulate the probability of myosin binding to actin and could help explain the acceleration of cross-bridge interactions with actin when cMyBP-C is phosphorylated because of, for example, activation of β1-adrenergic receptors in myocardium.
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Affiliation(s)
- Robert W Kensler
- Department of Anatomy and Neurobiology, University of Puerto Rico Medical School, San Juan, PR 00936;
| | - Roger Craig
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, MA 01655
| | - Richard L Moss
- Department of Cell and Regenerative Biology, School of Medicine and Public Health, University of Wisconsin, Madison, WI 53705
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Mohamed IA, Krishnamoorthy NT, Nasrallah GK, Da'as SI. The Role of Cardiac Myosin Binding Protein C3 in Hypertrophic Cardiomyopathy-Progress and Novel Therapeutic Opportunities. J Cell Physiol 2017; 232:1650-1659. [PMID: 27731493 DOI: 10.1002/jcp.25639] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Accepted: 10/07/2016] [Indexed: 11/11/2022]
Abstract
Hypertrophic cardiomyopathy (HCM) is a common autosomal dominant genetic cardiovascular disorder marked by genetic and phenotypic heterogeneity. Mutations in the gene encodes the cardiac myosin-binding protein C, cMYBPC3 is amongst the various sarcomeric genes that are associated with HCM. These mutations produce mutated mRNAs and truncated cMyBP-C proteins. In this review, we will discuss the implications and molecular mechanisms involved in MYBPC3 different mutations. Further, we will highlight the novel targets that can be developed into potential therapeutics for the treatment of HMC. J. Cell. Physiol. 232: 1650-1659, 2017. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Iman A Mohamed
- Department of Biomedical Science, Zewail City of Science and Technology, Giza, Egypt
| | - Navaneethakrishnan T Krishnamoorthy
- Division of Experimental Genetics, Sidra Medical and Research Center, Doha, Qatar.,Heart Science Centre, National Heart and Lung Institute, Imperial College London, London, UK
| | - Gheyath K Nasrallah
- Department of Biomedical Science, College of Health Science, Qatar University, Doha, Qatar.,Biomedical Research Center, Qatar University, Doha, Qatar
| | - Sahar I Da'as
- Division of Experimental Genetics, Sidra Medical and Research Center, Doha, Qatar.,Department of Biomedical and Biological Sciences, Hamad Bin Khalifa University, Doha, Qatar
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35
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Abstract
In the last decade, improvements in electron microscopy and image processing have permitted significantly higher resolutions to be achieved (sometimes <1 nm) when studying isolated actin and myosin filaments. In the case of actin filaments the changing structure when troponin binds calcium ions can be followed using electron microscopy and single particle analysis to reveal what happens on each of the seven non-equivalent pseudo-repeats of the tropomyosin α-helical coiled-coil. In the case of the known family of myosin filaments not only are the myosin head arrangements under relaxing conditions being defined, but the latest analysis, also using single particle methods, is starting to reveal the way that the α-helical coiled-coil myosin rods are packed to give the filament backbones.
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Affiliation(s)
- John M Squire
- Muscle Contraction Group, School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, BS8 1TD, UK.
| | - Danielle M Paul
- Muscle Contraction Group, School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, BS8 1TD, UK
| | - Edward P Morris
- Division of Structural Biology, The Institute of Cancer Research, London, SW3 6JB, UK
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36
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The genetic basis of hypertrophic cardiomyopathy in cats and humans. J Vet Cardiol 2016; 17 Suppl 1:S53-73. [PMID: 26776594 DOI: 10.1016/j.jvc.2015.03.001] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Revised: 01/16/2015] [Accepted: 03/16/2015] [Indexed: 12/19/2022]
Abstract
Mutations in genes that encode for muscle sarcomeric proteins have been identified in humans and two breeds of domestic cats with hypertrophic cardiomyopathy (HCM). This article reviews the history, genetics, and pathogenesis of HCM in the two species in order to give veterinarians a perspective on the genetics of HCM. Hypertrophic cardiomyopathy in people is a genetic disease that has been called a disease of the sarcomere because the preponderance of mutations identified that cause HCM are in genes that encode for sarcomeric proteins (Maron and Maron, 2013). Sarcomeres are the basic contractile units of muscle and thus sarcomeric proteins are responsible for the strength, speed, and extent of muscle contraction. In people with HCM, the two most common genes affected by HCM mutations are the myosin heavy chain gene (MYH7), the gene that encodes for the motor protein β-myosin heavy chain (the sarcomeric protein that splits ATP to generate force), and the cardiac myosin binding protein-C gene (MYBPC3), a gene that encodes for the closely related structural and regulatory protein, cardiac myosin binding protein-C (cMyBP-C). To date, the two mutations linked to HCM in domestic cats (one each in Maine Coon and Ragdoll breeds) also occur in MYBPC3 (Meurs et al., 2005, 2007). This is a review of the genetics of HCM in both humans and domestic cats that focuses on the aspects of human genetics that are germane to veterinarians and on all aspects of feline HCM genetics.
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37
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Evaluation of the Mayo Clinic Phenotype-Based Genotype Predictor Score in Patients with Clinically Diagnosed Hypertrophic Cardiomyopathy. J Cardiovasc Transl Res 2016; 9:153-61. [PMID: 26914223 DOI: 10.1007/s12265-016-9681-5] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Accepted: 02/14/2016] [Indexed: 02/08/2023]
Abstract
Genetic testing for hypertrophic cardiomyopathy (HCM) can provide an important clinical marker for disease outcome and family screening. This study set out to validate our recently developed phenotype-based HCM genotype predictor score. Patients clinically diagnosed with HCM and evaluated by genetic counselors comprised the study cohort. Genotype score was derived based on clinical and echocardiographic variables. Total score was correlated with the yield of genetic testing. Of 564 HCM patients, 198 sought genetic testing (35 %; 55 % male; mean age at diagnosis, 50 ± 20 years). Of these, 101 patients (51 %) were genotype positive for a HCM-associated genetic mutation (55 % male; mean age at diagnosis, 42 ± 18 years). Cochran-Armitage analysis showed similar, statistically significant trends of increased yields for higher genotype scores for both the original and study cohort. Validated by the current study, this scoring system provides an easy-to-use, clinical tool to aid in determining the likelihood of a positive HCM genetic test.
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38
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Site-directed spectroscopy of cardiac myosin-binding protein C reveals effects of phosphorylation on protein structural dynamics. Proc Natl Acad Sci U S A 2016; 113:3233-8. [PMID: 26908877 DOI: 10.1073/pnas.1521281113] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
We have used the site-directed spectroscopies of time-resolved fluorescence resonance energy transfer (TR-FRET) and double electron-electron resonance (DEER), combined with complementary molecular dynamics (MD) simulations, to resolve the structure and dynamics of cardiac myosin-binding protein C (cMyBP-C), focusing on the N-terminal region. The results have implications for the role of this protein in myocardial contraction, with particular relevance to β-adrenergic signaling, heart failure, and hypertrophic cardiomyopathy. N-terminal cMyBP-C domains C0-C2 (C0C2) contain binding regions for potential interactions with both thick and thin filaments. Phosphorylation by PKA in the MyBP-C motif regulates these binding interactions. Our spectroscopic assays detect distances between pairs of site-directed probes on cMyBP-C. We engineered intramolecular pairs of labeling sites within cMyBP-C to measure, with high resolution, the distance and disorder in the protein's flexible regions using TR-FRET and DEER. Phosphorylation reduced the level of molecular disorder and the distribution of C0C2 intramolecular distances became more compact, with probes flanking either the motif between C1 and C2 or the Pro/Ala-rich linker (PAL) between C0 and C1. Further insight was obtained from microsecond MD simulations, which revealed a large structural change in the disordered motif region in which phosphorylation unmasks the surface of a series of residues on a stable α-helix within the motif with high potential as a protein-protein interaction site. These experimental and computational findings elucidate structural transitions in the flexible and dynamic portions of cMyBP-C, providing previously unidentified molecular insight into the modulatory role of this protein in cardiac muscle contractility.
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39
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van Dijk SJ, Witt CC, Harris SP. Normal cardiac contraction in mice lacking the proline-alanine rich region and C1 domain of cardiac myosin binding protein C. J Mol Cell Cardiol 2015; 88:124-32. [PMID: 26455481 DOI: 10.1016/j.yjmcc.2015.09.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Revised: 09/15/2015] [Accepted: 09/15/2015] [Indexed: 11/28/2022]
Abstract
Cardiac myosin binding protein C (cMyBP-C) is an essential regulator of cross bridge cycling. Through mechanisms that are incompletely understood the N-terminal domains (NTDs) of cMyBP-C can activate contraction even in the absence of calcium and can also inhibit cross bridge kinetics in the presence of calcium. In vitro studies indicated that the proline-alanine rich (p/a) region and C1 domain are involved in these processes, although effects were greater using human proteins compared to murine proteins (Shaffer et al. J Biomed Biotechnol 2010, 2010: 789798). We hypothesized that the p/a and C1 region are critical for the timing of contraction. In this study we tested this hypothesis using a mouse model lacking the p/a and C1 region (p/a-C1(-/-) mice) to investigate the in vivo relevance of these regions on cardiac performance. Surprisingly, hearts of adult p/a-C1(-/-) mice functioned normally both on a cellular and whole organ level. Force measurements in permeabilized cardiomyocytes from adult p/a-C1(-/-) mice and wild type (Wt) littermate controls demonstrated similar rates of force redevelopment both at submaximal and maximal activation. Maximal and passive force and calcium sensitivity of force were comparable between groups as well. Echocardiograms showed normal isovolumetric contraction times, fractional shortening and ejection fraction, indicating proper systolic function in p/a-C1(-/-) mouse hearts. p/a-C1(-/-) mice showed a slight but significant reduction in isovolumetric relaxation time compared to Wt littermates, yet this difference disappeared in older mice (7-8months of age). Moreover, stroke volume was preserved in p/a-C1(-/-) mice, corroborating sufficient time for normal filling of the heart. Overall, the hearts of p/a-C1(-/-) mice showed no signs of dysfunction even after chronic stress with an adrenergic agonist. Together, these results indicate that the p/a region and the C1 domain of cMyBP-C are not critical for normal cardiac contraction in mice and that these domains have little if any impact on cross bridge kinetics in mice. These results thus contrast with in vitro studies utilizing proteins encoding the human p/a region and C1 domain. More detailed insight in how individual domains of cMyBP-C function and interact, across species and over the wide spectrum of conditions in which the heart has to function, will be essential to a better understanding of how cMyBP-C tunes cardiac contraction.
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Affiliation(s)
- Sabine J van Dijk
- Department of Cellular and Molecular Medicine, University of Arizona, 1656 East Mabel Street, Tucson, AZ 85724, USA
| | - Christian C Witt
- Department of Anaesthesiology and Operative Intensive Care, University Hospital Mannheim, Medical Faculty Mannheim, Heidelberg University, Theodor-Kutzer-Ufer 1-3, 68167 Mannheim, Germany
| | - Samantha P Harris
- Department of Cellular and Molecular Medicine, University of Arizona, 1656 East Mabel Street, Tucson, AZ 85724, USA.
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Mouton J, Loos B, Moolman-Smook JC, Kinnear CJ. Ascribing novel functions to the sarcomeric protein, myosin binding protein H (MyBPH) in cardiac sarcomere contraction. Exp Cell Res 2014; 331:338-51. [PMID: 25449695 DOI: 10.1016/j.yexcr.2014.11.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2014] [Revised: 11/04/2014] [Accepted: 11/09/2014] [Indexed: 12/13/2022]
Abstract
Myosin binding protein H (MyBPH) is a protein of unknown function, which shares sequence and structural similarities with myosin binding protein C (cMyBPC), a protein frequently implicated in hypertrophic cardiomyopathy (HCM). Given the similarity between cMyBPC and MyBPH, we proposed that MyBPH, like cMyBPC, could be involved in HCM pathogenesis and we therefore sought to determine its function. We identified MyBPH-interacting proteins by using yeast two-hybrid (Y2H) analysis. The role of MyBPH and cMyBPC in cardiac cell contractility was analysed by measuring the planar cell surface area of differentiated H9c2 rat cardiomyocytes in response to β-adrenergic stress after siRNA knockdown of MyBPH and cMyBPC. Individual knockdown of either protein had no effect on cardiac contractility, while concurrent knockdowns reduced cardiac contractility. These proteins therefore functionally compensate for one another and are critical for cardiac contractility. We further show that both proteins co-localise with the autophagosomal membrane protein LC3, suggesting that both proteins are involved in autophagosomal membrane maturation processes. The results of this study ascribe novel functions to MyBPH, which may contribute to our understanding of its role in the sarcomere. This study provides evidence for a potential role of MyBPH in HCM, which warrants further investigation.
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Affiliation(s)
- Jomien Mouton
- DST/NRF Centre of Excellence for Biomedical Tuberculosis Research, MRC Centre for Tuberculosis Research, Division of Molecular Biology and Human Genetics, Faculty of Medicine and Health Sciences, Stellenbosch University, PO Box 19063, Francie van Zijl Drive, Tygerberg 7505, South Africa.
| | - Ben Loos
- Department of Physiological Sciences, Stellenbosch University, Private Bag X1, Merriman Street, Stellenbosch 7602, South Africa.
| | - Johanna C Moolman-Smook
- DST/NRF Centre of Excellence for Biomedical Tuberculosis Research, MRC Centre for Tuberculosis Research, Division of Molecular Biology and Human Genetics, Faculty of Medicine and Health Sciences, Stellenbosch University, PO Box 19063, Francie van Zijl Drive, Tygerberg 7505, South Africa.
| | - Craig J Kinnear
- DST/NRF Centre of Excellence for Biomedical Tuberculosis Research, MRC Centre for Tuberculosis Research, Division of Molecular Biology and Human Genetics, Faculty of Medicine and Health Sciences, Stellenbosch University, PO Box 19063, Francie van Zijl Drive, Tygerberg 7505, South Africa.
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41
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Orientation of myosin binding protein C in the cardiac muscle sarcomere determined by domain-specific immuno-EM. J Mol Biol 2014; 427:274-86. [PMID: 25451032 DOI: 10.1016/j.jmb.2014.10.023] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2014] [Revised: 10/07/2014] [Accepted: 10/08/2014] [Indexed: 01/09/2023]
Abstract
Myosin binding protein C is a thick filament protein of vertebrate striated muscle. The cardiac isoform [cardiac myosin binding protein C (cMyBP-C)] is essential for normal cardiac function, and mutations in cMyBP-C cause cardiac muscle disease. The rod-shaped molecule is composed primarily of 11 immunoglobulin- or fibronectin-like domains and is located at nine sites, 43nm apart, in each half of the A-band. To understand how cMyBP-C functions, it is important to know its structural organization in the sarcomere, as this will affect its ability to interact with other sarcomeric proteins. Several models, in which cMyBP-C wraps around, extends radially from, or runs axially along the thick filament, have been proposed. Our goal was to define cMyBP-C orientation by determining the relative axial positions of different cMyBP-C domains. Immuno-electron microscopy was performed using mouse cardiac myofibrils labeled with antibodies specific to the N- and C-terminal domains and to the middle of cMyBP-C. Antibodies to all regions of the molecule, except the C-terminus, labeled at the same nine axial positions in each half A-band, consistent with a circumferential and/or radial rather than an axial orientation of the bulk of the molecule. The C-terminal antibody stripes were slightly displaced axially, demonstrating an axial orientation of the C-terminal three domains, with the C-terminus closer to the M-line. These results, combined with previous studies, suggest that the C-terminal domains of cMyBP-C run along the thick filament surface, while the N-terminus extends toward neighboring thin filaments. This organization provides a structural framework for understanding cMyBP-C's modulation of cardiac muscle contraction.
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42
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Belknap B, Harris SP, White HD. Modulation of thin filament activation of myosin ATP hydrolysis by N-terminal domains of cardiac myosin binding protein-C. Biochemistry 2014; 53:6717-24. [PMID: 25265574 PMCID: PMC4211651 DOI: 10.1021/bi500787f] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
![]()
We
have used enzyme kinetics to investigate the molecular mechanism
by which the N-terminal domains of human and mouse cardiac MyBP-C
(C0C1, C1C2, and C0C2) affect the activation of myosin ATP hydrolysis
by F-actin and by native porcine thin filaments. N-Terminal domains
of cMyBP-C inhibit the activation of myosin-S1 ATPase by F-actin.
However, mouse and human C1C2 and C0C2 produce biphasic activating
and inhibitory effects on the activation of myosin ATP hydrolysis
by native cardiac thin filaments. Low ratios of MyBP-C N-terminal
domains to thin filaments activate myosin-S1 ATP hydrolysis, but higher
ratios inhibit ATP hydrolysis, as is observed with F-actin alone.
These data suggest that low concentrations of C1C2 and C0C2 activate
thin filaments by a mechanism similar to that of rigor myosin-S1,
whereas higher concentrations inhibit the ATPase rate by competing
with myosin-S1-ADP-Pi for binding to actin and thin filaments.
In contrast to C0C2 and C1C2, the activating effects of the C0C1 domain
are species-dependent: human C0C1 activates actomyosin-S1 ATPase rates,
but mouse C0C1 does not produce significant activation or inhibition.
Phosphorylation of serine residues in the m-linker between the C1
and C2 domains by protein kinase-A decreases the activation of thin
filaments by huC0C2 at pCa > 8 but
has
little effect on the activation mechanism at pCa = 4. In sarcomeres, the low ratio of cMyBP-C to actin is
expected to favor the activating effects of cMyBP-C while minimizing
inhibition produced by competition with myosin heads.
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Affiliation(s)
- Betty Belknap
- Department of Physiological Sciences, Eastern Virginia Medical School , Norfolk, Virginia 23507, United States
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43
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Pirolli D, Sciandra F, Bozzi M, Giardina B, Brancaccio A, De Rosa MC. Insights from molecular dynamics simulations: structural basis for the V567D mutation-induced instability of zebrafish alpha-dystroglycan and comparison with the murine model. PLoS One 2014; 9:e103866. [PMID: 25078606 PMCID: PMC4117597 DOI: 10.1371/journal.pone.0103866] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2014] [Accepted: 07/03/2014] [Indexed: 11/19/2022] Open
Abstract
A missense amino acid mutation of valine to aspartic acid in 567 position of alpha-dystroglycan (DG), identified in dag1-mutated zebrafish, results in a reduced transcription and a complete absence of the protein. Lacking experimental structural data for zebrafish DG domains, the detailed mechanism for the observed mutation-induced destabilization of the DG complex and membrane damage, remained unclear. With the aim to contribute to a better clarification of the structure-function relationships featuring the DG complex, three-dimensional structural models of wild-type and mutant (V567D) C-terminal domain of alpha-DG from zebrafish were constructed by a template-based modelling approach. We then ran extensive molecular dynamics (MD) simulations to reveal the structural and dynamic properties of the C-terminal domain and to evaluate the effect of the single mutation on alpha-DG stability. A comparative study has been also carried out on our previously generated model of murine alpha-DG C-terminal domain including the I591D mutation, which is topologically equivalent to the V567D mutation found in zebrafish. Trajectories from MD simulations were analyzed in detail, revealing extensive structural disorder involving multiple beta-strands in the mutated variant of the zebrafish protein whereas local effects have been detected in the murine protein. A biochemical analysis of the murine alpha-DG mutant I591D confirmed a pronounced instability of the protein. Taken together, the computational and biochemical analysis suggest that the V567D/I591D mutation, belonging to the G beta-strand, plays a key role in inducing a destabilization of the alpha-DG C-terminal Ig-like domain that could possibly affect and propagate to the entire DG complex. The structural features herein identified may be of crucial help to understand the molecular basis of primary dystroglycanopathies.
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Affiliation(s)
- Davide Pirolli
- Istituto di Biochimica e Biochimica Clinica, Università Cattolica del Sacro Cuore, Rome, Italy
| | - Francesca Sciandra
- Istituto di Chimica del Riconoscimento Molecolare (ICRM) - CNR c/o Università Cattolica del Sacro Cuore, Rome, Italy
| | - Manuela Bozzi
- Istituto di Biochimica e Biochimica Clinica, Università Cattolica del Sacro Cuore, Rome, Italy
| | - Bruno Giardina
- Istituto di Biochimica e Biochimica Clinica, Università Cattolica del Sacro Cuore, Rome, Italy
- Istituto di Chimica del Riconoscimento Molecolare (ICRM) - CNR c/o Università Cattolica del Sacro Cuore, Rome, Italy
| | - Andrea Brancaccio
- Istituto di Chimica del Riconoscimento Molecolare (ICRM) - CNR c/o Università Cattolica del Sacro Cuore, Rome, Italy
| | - Maria Cristina De Rosa
- Istituto di Chimica del Riconoscimento Molecolare (ICRM) - CNR c/o Università Cattolica del Sacro Cuore, Rome, Italy
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Gresham KS, Mamidi R, Stelzer JE. The contribution of cardiac myosin binding protein-c Ser282 phosphorylation to the rate of force generation and in vivo cardiac contractility. J Physiol 2014; 592:3747-65. [PMID: 24951619 DOI: 10.1113/jphysiol.2014.276022] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Cardiac myosin binding protein-C phosphorylation plays an important role in modulating cardiac muscle function and accelerating contraction. It has been proposed that Ser282 phosphorylation may serve as a critical molecular switch that regulates the phosphorylation of neighbouring Ser273 and Ser302 residues, and thereby govern myofilament contractile acceleration in response to protein kinase A (PKA). Therefore, to determine the regulatory roles of Ser282 we generated a transgenic (TG) mouse model expressing cardiac myosin binding protein-C with a non-phosphorylatable Ser282 (i.e. serine to alanine substitution, TG(S282A)). Myofibrils isolated from TG(S282A) hearts displayed robust PKA-mediated phosphorylation of Ser273 and Ser302, and the increase in phosphorylation was identical to TG wild-type (TG(WT)) controls. No signs of pathological cardiac hypertrophy were detected in TG(S282A) hearts by either histological examination of cardiac sections or echocardiography. Baseline fractional shortening, ejection fraction, isovolumic relaxation time, rate of pressure development and rate of relaxation (τ) were unaltered in TG(S282A) mice. However, the increase in cardiac contractility as well as the acceleration of pressure development observed in response to β-adrenergic stimulation was attenuated in TG(S282A) mice. In agreement with our in vivo data, in vitro force measurements revealed that PKA-mediated acceleration of cross-bridge kinetics in TG(S282A) myocardium was significantly attenuated compared to TG(WT) myocardium. Taken together, our data suggest that while Ser282 phosphorylation does not regulate the phosphorylation of neighbouring Ser residues and basal cardiac function, full acceleration of cross-bridge kinetics and left ventricular pressure development cannot be achieved in its absence.
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Affiliation(s)
- Kenneth S Gresham
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Ranganath Mamidi
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Julian E Stelzer
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH, 44106, USA
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45
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De Lange WJ, Grimes AC, Hegge LF, Spring AM, Brost TM, Ralphe JC. E258K HCM-causing mutation in cardiac MyBP-C reduces contractile force and accelerates twitch kinetics by disrupting the cMyBP-C and myosin S2 interaction. ACTA ACUST UNITED AC 2014; 142:241-55. [PMID: 23980194 PMCID: PMC3753599 DOI: 10.1085/jgp.201311018] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Mutations in cardiac myosin binding protein C (cMyBP-C) are prevalent causes of hypertrophic cardiomyopathy (HCM). Although HCM-causing truncation mutations in cMyBP-C are well studied, the growing number of disease-related cMyBP-C missense mutations remain poorly understood. Our objective was to define the primary contractile effect and molecular disease mechanisms of the prevalent cMyBP-C E258K HCM-causing mutation in nonremodeled murine engineered cardiac tissue (mECT). Wild-type and human E258K cMyBP-C were expressed in mECT lacking endogenous mouse cMyBP-C through adenoviral-mediated gene transfer. Expression of E258K cMyBP-C did not affect cardiac cell survival and was appropriately incorporated into the cardiac sarcomere. Functionally, expression of E258K cMyBP-C caused accelerated contractile kinetics and severely compromised twitch force amplitude in mECT. Yeast two-hybrid analysis revealed that E258K cMyBP-C abolished interaction between the N terminal of cMyBP-C and myosin heavy chain sub-fragment 2 (S2). Furthermore, this mutation increased the affinity between the N terminal of cMyBP-C and actin. Assessment of phosphorylation of three serine residues in cMyBP-C showed that aberrant phosphorylation of cMyBP-C is unlikely to be responsible for altering these interactions. We show that the E258K mutation in cMyBP-C abolishes interaction between N-terminal cMyBP-C and myosin S2 by directly disrupting the cMyBP-C-S2 interface, independent of cMyBP-C phosphorylation. Similar to cMyBP-C ablation or phosphorylation, abolition of this inhibitory interaction accelerates contractile kinetics. Additionally, the E258K mutation impaired force production of mECT, which suggests that in addition to the loss of physiological function, this mutation disrupts contractility possibly by tethering the thick and thin filament or acting as an internal load.
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Affiliation(s)
- Willem J De Lange
- Department of Pediatrics, University of Wisconsin School of Medicine and Public Health, Madison, WI 53705, USA
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46
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Previs MJ, Michalek AJ, Warshaw DM. Molecular modulation of actomyosin function by cardiac myosin-binding protein C. Pflugers Arch 2014; 466:439-44. [PMID: 24407948 PMCID: PMC3932558 DOI: 10.1007/s00424-013-1433-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2013] [Accepted: 12/23/2013] [Indexed: 11/29/2022]
Abstract
Cardiac myosin-binding protein C is a key regulator of cardiac contractility and is capable of both activating the thin filament to initiate actomyosin motion generation and governing maximal sliding velocities. While MyBP-C's C terminus localizes the molecule within the sarcomere, the N terminus appears to confer regulatory function by binding to the myosin motor domain and/or actin. Literature pertaining to how MyBP-C binding to the myosin motor domain and or actin leads to MyBP-C's dual modulatory roles that can impact actomyosin interactions are discussed.
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Affiliation(s)
- Michael J Previs
- Department of Molecular Physiology & Biophysics, University of Vermont, 149 Beaumont Ave., HSRF Building Rm.-116, Burlington, VT, 05405, USA
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47
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Myosin-binding protein C displaces tropomyosin to activate cardiac thin filaments and governs their speed by an independent mechanism. Proc Natl Acad Sci U S A 2014; 111:2170-5. [PMID: 24477690 DOI: 10.1073/pnas.1316001111] [Citation(s) in RCA: 119] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Myosin-binding protein C (MyBP-C) is an accessory protein of striated muscle thick filaments and a modulator of cardiac muscle contraction. Defects in the cardiac isoform, cMyBP-C, cause heart disease. cMyBP-C includes 11 Ig- and fibronectin-like domains and a cMyBP-C-specific motif. In vitro studies show that in addition to binding to the thick filament via its C-terminal region, cMyBP-C can also interact with actin via its N-terminal domains, modulating thin filament motility. Structural observations of F-actin decorated with N-terminal fragments of cMyBP-C suggest that cMyBP-C binds to actin close to the low Ca(2+) binding site of tropomyosin. This suggests that cMyBP-C might modulate thin filament activity by interfering with tropomyosin regulatory movements on actin. To determine directly whether cMyBP-C binding affects tropomyosin position, we have used electron microscopy and in vitro motility assays to study the structural and functional effects of N-terminal fragments binding to thin filaments. 3D reconstructions suggest that under low Ca(2+) conditions, cMyBP-C displaces tropomyosin toward its high Ca(2+) position, and that this movement corresponds to thin filament activation in the motility assay. At high Ca(2+), cMyBP-C had little effect on tropomyosin position and caused slowing of thin filament sliding. Unexpectedly, a shorter N-terminal fragment did not displace tropomyosin or activate the thin filament at low Ca(2+) but slowed thin filament sliding as much as the larger fragments. These results suggest that cMyBP-C may both modulate thin filament activity, by physically displacing tropomyosin from its low Ca(2+) position on actin, and govern contractile speed by an independent molecular mechanism.
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Finley NL, Cuperman TI. Cardiac myosin binding protein-C: a structurally dynamic regulator of myocardial contractility. Pflugers Arch 2014; 466:433-8. [PMID: 24469349 DOI: 10.1007/s00424-014-1451-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2013] [Revised: 01/10/2014] [Accepted: 01/14/2014] [Indexed: 11/28/2022]
Abstract
Cardiac myosin binding protein-C (cMyBP-C) is a modular protein anchored to the thick filament through interactions mediated by its C-terminal region. The N-terminal region of cMyBPC-C regulates myocardial contractility by modifying actin-myosin association. Phosphorylation of the N-terminal region diminishes cMyBP-C's capacity to regulate actin-myosin function. Despite a substantial body of literature, many issues remain unclear regarding the structural and functional roles of cMyBP-C. While no high-resolution structures of the intact protein exist, crystallographic and nuclear magnetic resonance (NMR) structures of isolated N-terminal domains provide important molecular details regarding cMyBP-C's role in controlling contractility. In this review, we summarize the emerging structural understanding of cMyBP-C with a particular emphasis placed on describing how its dynamic molecular interactions with both thin and thick filament proteins likely contribute to contractile regulation. Furthermore, we discuss the future directions and strategies by which we may improve the mechanistic understanding of its role in modulating cardiac muscle contraction.
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Affiliation(s)
- Natosha L Finley
- The Cell, Molecular, and Structural Biology Program, Department of Microbiology, Miami University, 700 East High Street, 32 Pearson Hall, Oxford, OH, 45056, USA,
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van Dijk SJ, Bezold KL, Harris SP. Earning stripes: myosin binding protein-C interactions with actin. Pflugers Arch 2014; 466:445-50. [PMID: 24442149 DOI: 10.1007/s00424-013-1432-8] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2013] [Accepted: 12/23/2013] [Indexed: 01/23/2023]
Abstract
Myosin binding protein-C (MyBP-C) was first discovered as an impurity during the purification of myosin from skeletal muscle. However, soon after its discovery, MyBP-C was also shown to bind actin. While the unique functional implications for a protein that could cross-link thick and thin filaments together were immediately recognized, most early research nonetheless focused on interactions of MyBP-C with the thick filament. This was in part because interactions of MyBP-C with the thick filament could adequately explain most (but not all) effects of MyBP-C on actomyosin interactions and in part because the specificity of actin binding was uncertain. However, numerous recent studies have now established that MyBP-C can indeed bind to actin through multiple binding sites, some of which are highly specific. Many of these interactions involve critical regulatory domains of MyBP-C that are also reported to interact with myosin. Here we review current evidence supporting MyBP-C interactions with actin and discuss these findings in terms of their ability to account for the functional effects of MyBP-C. We conclude that the influence of MyBP-C on muscle contraction can be explained equally well by interactions with actin as by interactions with myosin. However, because data showing that MyBP-C binds to either myosin or actin has come almost exclusively from in vitro biochemical studies, the challenge for future studies is to define which binding partner(s) MyBP-C interacts with in vivo.
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Affiliation(s)
- Sabine J van Dijk
- Department of Cellular and Molecular Medicine, University of Arizona, Medical Research Building, 1656 East Mabel Street, Tucson, AZ, 85724-5217, USA
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Cardiac myosin-binding protein-C is a critical mediator of diastolic function. Pflugers Arch 2014; 466:451-7. [PMID: 24442121 PMCID: PMC3928517 DOI: 10.1007/s00424-014-1442-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2013] [Revised: 12/23/2013] [Accepted: 01/03/2014] [Indexed: 12/25/2022]
Abstract
Diastolic dysfunction prominently contributes to heart failure with preserved ejection fraction (HFpEF). Owing partly to inadequate understanding, HFpEF does not have any effective treatments. Cardiac myosin-binding protein-C (cMyBP-C), a component of the thick filament of heart muscle that can modulate cross-bridge attachment/detachment cycling process by its phosphorylation status, appears to be involved in the diastolic dysfunction associated with HFpEF. In patients, cMyBP-C mutations are associated with diastolic dysfunction even in the absence of hypertrophy. cMyBP-C deletion mouse models recapitulate diastolic dysfunction despite in vitro evidence of uninhibited cross-bridge cycling. Reduced phosphorylation of cMyBP-C is also associated with diastolic dysfunction in patients. Mouse models of reduced cMyBP-C phosphorylation exhibit diastolic dysfunction while cMyBP-C phosphorylation mimetic mouse models show enhanced diastolic function. Thus, cMyBP-C phosphorylation mediates diastolic function. Experimental results of both cMyBP-C deletion and reduced cMyBP-C phosphorylation causing diastolic dysfunction suggest that cMyBP-C phosphorylation level modulates cross-bridge detachment rate in relation to ongoing attachment rate to mediate relaxation. Consequently, alteration in cMyBP-C regulation of cross-bridge detachment is a key mechanism that causes diastolic dysfunction. Regardless of the exact molecular mechanism, ample clinical and experimental data show that cMyBP-C is a critical mediator of diastolic function. Furthermore, targeting cMyBP-C phosphorylation holds potential as a future treatment for diastolic dysfunction.
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