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Doh CY, Schmidt AV, Chinthalapudi K, Stelzer JE. Bringing into focus the central domains C3-C6 of myosin binding protein C. Front Physiol 2024; 15:1370539. [PMID: 38487262 PMCID: PMC10937550 DOI: 10.3389/fphys.2024.1370539] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2024] [Accepted: 02/19/2024] [Indexed: 03/17/2024] Open
Abstract
Myosin binding protein C (MyBPC) is a multi-domain protein with each region having a distinct functional role in muscle contraction. The central domains of MyBPC have often been overlooked due to their unclear roles. However, recent research shows promise in understanding their potential structural and regulatory functions. Understanding the central region of MyBPC is important because it may have specialized function that can be used as drug targets or for disease-specific therapies. In this review, we provide a brief overview of the evolution of our understanding of the central domains of MyBPC in regard to its domain structures, arrangement and dynamics, interaction partners, hypothesized functions, disease-causing mutations, and post-translational modifications. We highlight key research studies that have helped advance our understanding of the central region. Lastly, we discuss gaps in our current understanding and potential avenues to further research and discovery.
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Affiliation(s)
- Chang Yoon Doh
- Department of Medicine, School of Medicine, Case Western Reserve University, Cleveland, OH, United States
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH, United States
| | - Alexandra V. Schmidt
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH, United States
| | - Krishna Chinthalapudi
- Department of Physiology and Cell Biology, Dorothy M. Davis Heart & Lung Research Institute, College of Medicine, The Ohio State University, Columbus, OH, United States
| | - Julian E. Stelzer
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH, United States
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2
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Caudal A, Snyder MP, Wu JC. Harnessing human genetics and stem cells for precision cardiovascular medicine. CELL GENOMICS 2024; 4:100445. [PMID: 38359791 PMCID: PMC10879032 DOI: 10.1016/j.xgen.2023.100445] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2023] [Revised: 09/22/2023] [Accepted: 10/25/2023] [Indexed: 02/17/2024]
Abstract
Human induced pluripotent stem cell (iPSC) platforms are valuable for biomedical and pharmaceutical research by providing tissue-specific human cells that retain patients' genetic integrity and display disease phenotypes in a dish. Looking forward, combining iPSC phenotyping platforms with genomic and screening technologies will continue to pave new directions for precision medicine, including genetic prediction, visualization, and treatment of heart disease. This review summarizes the recent use of iPSC technology to unpack the influence of genetic variants in cardiovascular pathology. We focus on various state-of-the-art genomic tools for cardiovascular therapies-including the expansion of genetic toolkits for molecular interrogation, in vitro population studies, and function-based drug screening-and their current applications in patient- and genome-edited iPSC platforms that are heralding new avenues for cardiovascular research.
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Affiliation(s)
- Arianne Caudal
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA 94305, USA; Division of Cardiovascular Medicine, Department of Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Michael P Snyder
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Joseph C Wu
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA 94305, USA; Division of Cardiovascular Medicine, Department of Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA; Greenstone Biosciences, Palo Alto, CA 94304, USA.
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3
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De Lange WJ, Farrell ET, Hernandez JJ, Stempien A, Kreitzer CR, Jacobs DR, Petty DL, Moss RL, Crone WC, Ralphe JC. cMyBP-C ablation in human engineered cardiac tissue causes progressive Ca2+-handling abnormalities. J Gen Physiol 2023; 155:e202213204. [PMID: 36893011 PMCID: PMC10038829 DOI: 10.1085/jgp.202213204] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Revised: 01/02/2023] [Accepted: 02/14/2023] [Indexed: 03/10/2023] Open
Abstract
Truncation mutations in cardiac myosin binding protein C (cMyBP-C) are common causes of hypertrophic cardiomyopathy (HCM). Heterozygous carriers present with classical HCM, while homozygous carriers present with early onset HCM that rapidly progress to heart failure. We used CRISPR-Cas9 to introduce heterozygous (cMyBP-C+/-) and homozygous (cMyBP-C-/-) frame-shift mutations into MYBPC3 in human iPSCs. Cardiomyocytes derived from these isogenic lines were used to generate cardiac micropatterns and engineered cardiac tissue constructs (ECTs) that were characterized for contractile function, Ca2+-handling, and Ca2+-sensitivity. While heterozygous frame shifts did not alter cMyBP-C protein levels in 2-D cardiomyocytes, cMyBP-C+/- ECTs were haploinsufficient. cMyBP-C-/- cardiac micropatterns produced increased strain with normal Ca2+-handling. After 2 wk of culture in ECT, contractile function was similar between the three genotypes; however, Ca2+-release was slower in the setting of reduced or absent cMyBP-C. At 6 wk in ECT culture, the Ca2+-handling abnormalities became more pronounced in both cMyBP-C+/- and cMyBP-C-/- ECTs, and force production became severely depressed in cMyBP-C-/- ECTs. RNA-seq analysis revealed enrichment of differentially expressed hypertrophic, sarcomeric, Ca2+-handling, and metabolic genes in cMyBP-C+/- and cMyBP-C-/- ECTs. Our data suggest a progressive phenotype caused by cMyBP-C haploinsufficiency and ablation that initially is hypercontractile, but progresses to hypocontractility with impaired relaxation. The severity of the phenotype correlates with the amount of cMyBP-C present, with more severe earlier phenotypes observed in cMyBP-C-/- than cMyBP-C+/- ECTs. We propose that while the primary effect of cMyBP-C haploinsufficiency or ablation may relate to myosin crossbridge orientation, the observed contractile phenotype is Ca2+-mediated.
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Affiliation(s)
- Willem J. De Lange
- Departments of Pediatrics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA
| | - Emily T. Farrell
- Departments of Pediatrics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA
| | - Jonathan J. Hernandez
- Departments of Pediatrics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA
| | - Alana Stempien
- Departments of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, USA
- Wisconsin Institute for Discovery, University of Wisconsin-Madison, Madison, WI, USA
| | - Caroline R. Kreitzer
- Departments of Pediatrics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA
| | - Derek R. Jacobs
- Departments of Pediatrics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA
| | - Dominique L. Petty
- Departments of Pediatrics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA
| | - Richard L. Moss
- Cell and Regenerative Biology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA
| | - Wendy C. Crone
- Departments of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, USA
- Wisconsin Institute for Discovery, University of Wisconsin-Madison, Madison, WI, USA
- Engineering Physics, University of Wisconsin-Madison, Madison, WI, USA
- Materials Science and Engineering, University of Wisconsin-Madison, Madison, WI, USA
| | - J. Carter Ralphe
- Departments of Pediatrics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA
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Yousaf M, Khan WA, Shahzad K, Khan HN, Ali B, Hussain M, Awan FR, Mustafa H, Sheikh FN. Genetic Association of Beta-Myosin Heavy-Chain Gene (MYH7) with Cardiac Dysfunction. Genes (Basel) 2022; 13:genes13091554. [PMID: 36140722 PMCID: PMC9498774 DOI: 10.3390/genes13091554] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2022] [Revised: 08/19/2022] [Accepted: 08/24/2022] [Indexed: 11/16/2022] Open
Abstract
Cardiac dysfunction accelerates the risk of heart failure, and its pathogenesis involves a complex interaction between genetic and environmental factors. Variations in myosin affect contractile abilities of cardiomyocytes and cause structural and functional abnormalities in myocardium. The study aims to find the association of MYH7 rs121913642 (c.1594 T>C) and rs121913645 (c.667G>A) variants with cardiac dysfunction in the Punjabi Pakistani population. Patients with heart failure (n = 232) and healthy controls (n = 205) were enrolled in this study. MYH7 variant genotyping was performed using tetra ARMS-PCR. MYH7 rs121913642 TC genotype was significantly more prevalent in the patient group (p < 0.001). However, MYH7 rs121913645 genotype frequencies were not significantly different between the patient and control groups (p < 0.666). Regression analysis also revealed that the rs121913642 C allele increases the risk of cardiac failure by ~2 [OR:1.98, CI: 1.31−2.98, p < 0.001] in comparison to the T allele. High levels of the cardiac enzymes cardiac troponin I (cTnI) and CK-MB were observed in patients. There was also an increase in total cholesterol, LDL cholesterol, and uric acid in patients compared to the healthy control group (p < 0.001). In conclusion, the MYH7 gene variant rs121913642 is genetically associated with cardiac dysfunction and involved in the pathogenesis of HF.
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Affiliation(s)
- Memoona Yousaf
- Department of Biotechnology, University of Sargodha, Sargodha 40100, Pakistan
| | - Waqas Ahmed Khan
- Department of Biotechnology, University of Sargodha, Sargodha 40100, Pakistan
- Correspondence: (W.A.K.); (H.M.); Tel.: +92-321-9331563 (W.A.K.)
| | - Khurrum Shahzad
- Department of Biotechnology, University of Sargodha, Sargodha 40100, Pakistan
- Institute of Clinical Chemistry, University Hospital Leipzig Institute of Clinical Chemistry Liebigstraße27, D-04103 Leipzig, Germany
| | - Haq Nawaz Khan
- Diabetes and Cardio-Metabolic Disorders Laboratory, Health Biotechnology Division, National Institute for Biotechnology and Genetic Engineering (NIBGE), Faisalabad 38000, Pakistan
| | - Basharat Ali
- Department of Family Medicine, University of Health Sciences, Lahore 42000, Pakistan
| | - Misbah Hussain
- Department of Biotechnology, University of Sargodha, Sargodha 40100, Pakistan
- Diabetes and Cardio-Metabolic Disorders Laboratory, Health Biotechnology Division, National Institute for Biotechnology and Genetic Engineering (NIBGE), Faisalabad 38000, Pakistan
| | - Fazli Rabbi Awan
- Diabetes and Cardio-Metabolic Disorders Laboratory, Health Biotechnology Division, National Institute for Biotechnology and Genetic Engineering (NIBGE), Faisalabad 38000, Pakistan
| | - Hamid Mustafa
- Department of Animal Breeding & Genetics, University of Veterinary and Animal Sciences, Lahore 42000, Pakistan
- Correspondence: (W.A.K.); (H.M.); Tel.: +92-321-9331563 (W.A.K.)
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5
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Touma AM, Tang W, Rasicci DV, Vang D, Rai A, Previs SB, Warshaw DM, Yengo CM, Sivaramakrishnan S. Nanosurfer Assay Dissects β-Cardiac Myosin and Cardiac Myosin-Binding Protein C Interactions. Biophys J 2022; 121:2449-2460. [PMID: 35591788 DOI: 10.1016/j.bpj.2022.05.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Revised: 04/13/2022] [Accepted: 05/13/2022] [Indexed: 11/02/2022] Open
Abstract
Cardiac myosin-binding protein C (cMyBP-C) modulates cardiac contractility through putative interactions with the myosin S2 tail and/or the thin filament. The relative contribution of these binding-partner interactions to cMyBP-C modulatory function remains unclear. Hence, we developed a "nanosurfer" assay as a model system to interrogate these cMyBP-C binding-partner interactions. Synthetic thick filaments were generated using recombinant human β-cardiac myosin subfragments (HMM or S1) attached to DNA nanotubes, with 14 or 28 nm spacing, corresponding to the 14.3 nm myosin spacing in native thick filaments. The nanosurfer assay consists of DNA nanotubes added to the in vitro motility assay so that myosins on the motility surface effectively deliver thin filaments to the DNA nanotubes, enhancing thin filament gliding probability on the DNA nanotubes. Thin filament velocities on nanotubes with either 14 or 28 nm myosin spacing were no different. We then characterized the effects of cMyBP-C on thin filament motility by alternating HMM and cMyBP-C N-terminal fragments (C0-C2 or C1-C2) on nanotubes every 14 nm. Both C0-C2 and C1-C2 reduced thin filament velocity 4-6 fold relative to HMM alone. Similar inhibition occurred using the myosin S1 construct, which lacks the myosin S2 region proposed to interact with cMyBP-C, suggesting that the cMyBP-C N-terminus must interact with other myosin head domains and/or actin to slow thin filament velocity. Thin filament velocity was unaffected by the C0-C1f fragment, which lacks the majority of the M-domain, supporting the importance of this domain for inhibitory interaction(s). A C0-C2 fragment with phosphomimetic replacement in the M-domain showed markedly less inhibition of thin filament velocity compared to its phosphonull counterpart, highlighting the modulatory role of M-domain phosphorylation on cMyBP-C function. Therefore, the nanosurfer assay provides a platform to precisely manipulate spatially dependent cMyBP-C binding partner interactions, shedding light on the molecular regulation of β-cardiac myosin contractility.
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Affiliation(s)
- Anja M Touma
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, MN, USA
| | - Wanjian Tang
- Department of Cellular and Molecular Physiology, Penn State College of Medicine, Hershey, Pennsylvania, USA
| | - David V Rasicci
- Department of Cellular and Molecular Physiology, Penn State College of Medicine, Hershey, Pennsylvania, USA
| | - Duha Vang
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, MN, USA
| | - Ashim Rai
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, MN, USA
| | - Samantha B Previs
- Department of Molecular Physiology and Biophysics, Cardiovascular Research Institute, University of Vermont, Burlington, VT
| | - David M Warshaw
- Department of Molecular Physiology and Biophysics, Cardiovascular Research Institute, University of Vermont, Burlington, VT
| | - Christopher M Yengo
- Department of Cellular and Molecular Physiology, Penn State College of Medicine, Hershey, Pennsylvania, USA
| | - Sivaraj Sivaramakrishnan
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, MN, USA.
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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: 6] [Impact Index Per Article: 3.0] [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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Singh RR, McNamara JW, Sadayappan S. Mutations in myosin S2 alter cardiac myosin-binding protein-C interaction in hypertrophic cardiomyopathy in a phosphorylation-dependent manner. J Biol Chem 2021; 297:100836. [PMID: 34051236 PMCID: PMC8239744 DOI: 10.1016/j.jbc.2021.100836] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Revised: 05/18/2021] [Accepted: 05/25/2021] [Indexed: 12/31/2022] Open
Abstract
Hypertrophic cardiomyopathy (HCM) is an inherited cardiovascular disorder primarily caused by mutations in the β-myosin heavy-chain gene. The proximal subfragment 2 region (S2), 126 amino acids of myosin, binds with the C0-C2 region of cardiac myosin-binding protein-C to regulate cardiac muscle contractility in a manner dependent on PKA-mediated phosphorylation. However, it is unknown if HCM-associated mutations within S2 dysregulate actomyosin dynamics by disrupting its interaction with C0-C2, ultimately leading to HCM. Herein, we study three S2 mutations known to cause HCM: R870H, E924K, and E930Δ. First, experiments using recombinant proteins, solid-phase binding, and isothermal titrating calorimetry assays independently revealed that mutant S2 proteins displayed significantly reduced binding with C0-C2. In addition, CD revealed greater instability of the coiled-coil structure in mutant S2 proteins compared with S2Wt proteins. Second, mutant S2 exhibited 5-fold greater affinity for PKA-treated C0-C2 proteins. Third, skinned papillary muscle fibers treated with mutant S2 proteins showed no change in the rate of force redevelopment as a measure of actin–myosin cross-bridge kinetics, whereas S2Wt showed increased the rate of force redevelopment. In summary, S2 and C0-C2 interaction mediated by phosphorylation is altered by mutations in S2, which augment the speed and force of contraction observed in HCM. Modulating this interaction could be a potential strategy to treat HCM in the future.
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Affiliation(s)
- Rohit R Singh
- Division of Cardiovascular Health and Disease, Department of Internal Medicine, Heart, Lung and Vascular Institute, University of Cincinnati, Cincinnati, Ohio, USA
| | - James W McNamara
- Division of Cardiovascular Health and Disease, Department of Internal Medicine, Heart, Lung and Vascular Institute, University of Cincinnati, Cincinnati, Ohio, USA
| | - Sakthivel Sadayappan
- Division of Cardiovascular Health and Disease, Department of Internal Medicine, Heart, Lung and Vascular Institute, University of Cincinnati, Cincinnati, Ohio, USA.
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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 DOI: 10.1016/j.yjmcc.2021.03.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [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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9
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Bobyleva LG, Shumeyko SA, Yakupova EI, Surin AK, Galzitskaya OV, Kihara H, Timchenko AA, Timchenko MA, Penkov NV, Nikulin AD, Suvorina MY, Molochkov NV, Lobanov MY, Fadeev RS, Vikhlyantsev IM, Bobylev AG. Myosin Binding Protein-C Forms Amyloid-Like Aggregates In Vitro. Int J Mol Sci 2021; 22:ijms22020731. [PMID: 33450960 PMCID: PMC7828380 DOI: 10.3390/ijms22020731] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 01/06/2021] [Accepted: 01/10/2021] [Indexed: 11/17/2022] Open
Abstract
This work investigated in vitro aggregation and amyloid properties of skeletal myosin binding protein-C (sMyBP-C) interacting in vivo with proteins of thick and thin filaments in the sarcomeric A-disc. Dynamic light scattering (DLS) and transmission electron microscopy (TEM) found a rapid (5–10 min) formation of large (>2 μm) aggregates. sMyBP-C oligomers formed both at the initial 5–10 min and after 16 h of aggregation. Small angle X-ray scattering (SAXS) and DLS revealed sMyBP-C oligomers to consist of 7–10 monomers. TEM and atomic force microscopy (AFM) showed sMyBP-C to form amorphous aggregates (and, to a lesser degree, fibrillar structures) exhibiting no toxicity on cell culture. X-ray diffraction of sMyBP-C aggregates registered reflections attributed to a cross-β quaternary structure. Circular dichroism (CD) showed the formation of the amyloid-like structure to occur without changes in the sMyBP-C secondary structure. The obtained results indicating a high in vitro aggregability of sMyBP-C are, apparently, a consequence of structural features of the domain organization of proteins of this family. Formation of pathological amyloid or amyloid-like sMyBP-C aggregates in vivo is little probable due to amino-acid sequence low identity (<26%), alternating ordered/disordered regions in the protein molecule, and S–S bonds providing for general stability.
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Affiliation(s)
- Liya G. Bobyleva
- Laboratory of the Structure and Functions of Muscle Proteins, Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, 142290 Pushchino, Russia; (L.G.B.); (S.A.S.); (E.I.Y.); (O.V.G.)
| | - Sergey A. Shumeyko
- Laboratory of the Structure and Functions of Muscle Proteins, Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, 142290 Pushchino, Russia; (L.G.B.); (S.A.S.); (E.I.Y.); (O.V.G.)
| | - Elmira I. Yakupova
- Laboratory of the Structure and Functions of Muscle Proteins, Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, 142290 Pushchino, Russia; (L.G.B.); (S.A.S.); (E.I.Y.); (O.V.G.)
| | - Alexey K. Surin
- Laboratory of Bioinformatics and Proteomics, Institute of Protein Research, Russian Academy of Sciences, 142290 Pushchino, Russia; (A.K.S.); (M.Y.S.); (M.Y.L.)
- Biological Testing Laboratory, Branch of the Shemyakin–Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 142290 Pushchino, Russia
- Laboratory of the Biochemistry of Pathogenic Microorganisms, State Research Centre for Applied Microbiology and Biotechnology, Obolensk, 142279 Serpukhov District, Russia
| | - Oxana V. Galzitskaya
- Laboratory of the Structure and Functions of Muscle Proteins, Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, 142290 Pushchino, Russia; (L.G.B.); (S.A.S.); (E.I.Y.); (O.V.G.)
- Laboratory of Bioinformatics and Proteomics, Institute of Protein Research, Russian Academy of Sciences, 142290 Pushchino, Russia; (A.K.S.); (M.Y.S.); (M.Y.L.)
| | - Hiroshi Kihara
- Department of Early Childhood Education, Himeji-Hinomoto College, 890 Koro, Kodera-cho, Himeji 679-2151, Japan;
| | - Alexander A. Timchenko
- Group of Experimental Research and Engineering of Oligomeric Structures, Institute of Protein Research, Russian Academy of Sciences, 142290 Pushchino, Russia;
| | - Maria A. Timchenko
- Laboratory of Applied Enzymology, FRC PSCBR, Russian Academy of Sciences, 142290 Pushchino, Russia;
| | - Nikita V. Penkov
- Laboratory of the Methods of Optical Spectral Analysis, Institute of Cell Biophysics, Russian Academy of Sciences, FRC PSCBR RAS, 142290 Pushchino, Russia;
| | - Alexey D. Nikulin
- Laboratory for Structural Studies of the Translational Apparatus, Institute of Protein Research, Russian Academy of Sciences, 142290 Pushchino, Russia;
| | - Mariya Yu. Suvorina
- Laboratory of Bioinformatics and Proteomics, Institute of Protein Research, Russian Academy of Sciences, 142290 Pushchino, Russia; (A.K.S.); (M.Y.S.); (M.Y.L.)
| | - Nikolay V. Molochkov
- Laboratory of NMR Investigations of Biosystems, Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, 142290 Pushchino, Russia;
| | - Mikhail Yu. Lobanov
- Laboratory of Bioinformatics and Proteomics, Institute of Protein Research, Russian Academy of Sciences, 142290 Pushchino, Russia; (A.K.S.); (M.Y.S.); (M.Y.L.)
| | - Roman S. Fadeev
- Laboratory of Pharmacological Regulation of Cell Resistance, Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, 142290 Pushchino, Russia;
| | - Ivan M. Vikhlyantsev
- Laboratory of the Structure and Functions of Muscle Proteins, Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, 142290 Pushchino, Russia; (L.G.B.); (S.A.S.); (E.I.Y.); (O.V.G.)
- Correspondence: (I.M.V.); (A.G.B.)
| | - Alexander G. Bobylev
- Laboratory of the Structure and Functions of Muscle Proteins, Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, 142290 Pushchino, Russia; (L.G.B.); (S.A.S.); (E.I.Y.); (O.V.G.)
- Correspondence: (I.M.V.); (A.G.B.)
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10
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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 2020; 153:211574. [PMID: 33275758 PMCID: PMC7721898 DOI: 10.1085/jgp.202012729] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [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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11
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Main A, Fuller W, Baillie GS. Post-translational regulation of cardiac myosin binding protein-C: A graphical review. Cell Signal 2020; 76:109788. [DOI: 10.1016/j.cellsig.2020.109788] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Revised: 09/17/2020] [Accepted: 09/18/2020] [Indexed: 01/01/2023]
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12
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Role of Muscle-Specific Histone Methyltransferase (Smyd1) in Exercise-Induced Cardioprotection against Pathological Remodeling after Myocardial Infarction. Int J Mol Sci 2020; 21:ijms21197010. [PMID: 32977624 PMCID: PMC7582695 DOI: 10.3390/ijms21197010] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2020] [Revised: 09/07/2020] [Accepted: 09/21/2020] [Indexed: 12/18/2022] Open
Abstract
Pathological remodeling is the main detrimental complication after myocardial infarction (MI). Overproduction of reactive oxygen species (ROS) in infarcted myocardium may contribute to this process. Adequate exercise training after MI may reduce oxidative stress-induced cardiac tissue damage and remodeling. SET and MYND domain containing 1 (Smyd1) is a muscle-specific histone methyltransferase which is upregulated by resistance training, may strengthen sarcomere assembly and myofiber folding, and may promote skeletal muscles growth and hypertrophy. However, it remains elusive if Smyd1 has similar functions in post-MI cardiac muscle and participates in exercise-induced cardioprotection. Accordingly, we investigated the effects of interval treadmill exercise on cardiac function, ROS generation, Smyd1 expression, and sarcomere assembly of F-actin in normal and infarcted hearts. Adult male rats were randomly divided into five groups (n = 10/group): control (C), exercise alone (EX), sham-operated (S), MI induced by permanent ligation of left anterior descending coronary artery (MI), and MI with interval exercise training (MI + EX). Exercise training significantly improved post-MI cardiac function and sarcomere assembly of F-actin. The cardioprotective effects were associated with increased Smyd1, Trx1, cTnI, and α-actinin expression as well as upregulated ratio of phosphorylated AMP-activated protein kinase (AMPK)/AMPK, whereas Hsp90, MuRF1, brain natriuretic peptide (BNP) expression, ROS generation, and myocardial fibrosis were attenuated. The improved post-MI cardiac function was associated with increased Smyd1 expression. In cultured H9C2 cardiomyoblasts, in vitro treatment with H2O2 (50 µmol/L) or AMP-activated protein kinase (AMPK) agonist (AICAR, 1 mmol/L) or their combination for 4 h simulated the effects of exercise on levels of ROS and Smyd1. In conclusion, we demonstrated a novel role of Smyd1 in association with post-MI exercise-induced cardioprotection. The moderate level of ROS-induced upregulation of Smyd1 may be an important target for modulating post-MI cardiac function and remodeling.
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13
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Arif M, Nabavizadeh P, Song T, Desai D, Singh R, Bazrafshan S, Kumar M, Wang Y, Gilbert RJ, Dhandapany PS, Becker RC, Kranias EG, Sadayappan S. Genetic, clinical, molecular, and pathogenic aspects of the South Asian-specific polymorphic MYBPC3 Δ25bp variant. Biophys Rev 2020; 12:1065-1084. [PMID: 32656747 PMCID: PMC7429610 DOI: 10.1007/s12551-020-00725-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Accepted: 07/03/2020] [Indexed: 02/06/2023] Open
Abstract
Hypertrophic cardiomyopathy (HCM) is a cardiac genetic disease characterized by ventricular enlargement, diastolic dysfunction, and increased risk for sudden cardiac death. Sarcomeric genetic defects are the predominant known cause of HCM. In particular, mutations in the myosin-binding protein C gene (MYBPC3) are associated with ~ 40% of all HCM cases in which a genetic basis has been established. A decade ago, our group reported a 25-base pair deletion in intron 32 of MYBPC3 (MYBPC3Δ25bp) that is uniquely prevalent in South Asians and is associated with autosomal dominant cardiomyopathy. Although our studies suggest that this deletion results in left ventricular dysfunction, cardiomyopathies, and heart failure, the precise mechanism by which this variant predisposes to heart disease remains unclear. Increasingly appreciated, however, is the contribution of secondary risk factors, additional mutations, and lifestyle choices in augmenting or modifying the HCM phenotype in MYBPC3Δ25bp carriers. Therefore, the goal of this review article is to summarize the current research dedicated to understanding the molecular pathophysiology of HCM in South Asians with the MYBPC3Δ25bp variant. An emphasis is to review the latest techniques currently applied to explore the MYBPC3Δ25bp pathogenesis and to provide a foundation for developing new diagnostic strategies and advances in therapeutics.
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Affiliation(s)
- Mohammed Arif
- Division of Cardiovascular Health and Disease, Department of Internal Medicine, Heart, Lung and Vascular Institute, University of Cincinnati, College of Medicine, 231 Albert Sabin Way, Cincinnati, OH, 45267-0575, USA.
| | - Pooneh Nabavizadeh
- Division of Cardiovascular Health and Disease, Department of Internal Medicine, Heart, Lung and Vascular Institute, University of Cincinnati, College of Medicine, 231 Albert Sabin Way, Cincinnati, OH, 45267-0575, USA
| | - Taejeong Song
- Division of Cardiovascular Health and Disease, Department of Internal Medicine, Heart, Lung and Vascular Institute, University of Cincinnati, College of Medicine, 231 Albert Sabin Way, Cincinnati, OH, 45267-0575, USA
| | - Darshini Desai
- Division of Cardiovascular Health and Disease, Department of Internal Medicine, Heart, Lung and Vascular Institute, University of Cincinnati, College of Medicine, 231 Albert Sabin Way, Cincinnati, OH, 45267-0575, USA
| | - Rohit Singh
- Division of Cardiovascular Health and Disease, Department of Internal Medicine, Heart, Lung and Vascular Institute, University of Cincinnati, College of Medicine, 231 Albert Sabin Way, Cincinnati, OH, 45267-0575, USA
| | - Sholeh Bazrafshan
- Division of Cardiovascular Health and Disease, Department of Internal Medicine, Heart, Lung and Vascular Institute, University of Cincinnati, College of Medicine, 231 Albert Sabin Way, Cincinnati, OH, 45267-0575, USA
| | - Mohit Kumar
- Division of Cardiovascular Health and Disease, Department of Internal Medicine, Heart, Lung and Vascular Institute, University of Cincinnati, College of Medicine, 231 Albert Sabin Way, Cincinnati, OH, 45267-0575, USA
| | - Yigang Wang
- Department of Pathology and Laboratory Medicine, University of Cincinnati, College of Medicine, Cincinnati, OH, 45267, USA
| | - Richard J Gilbert
- Research Service, Providence VA Medical Center, Providence, RI, 02908, USA
| | - Perundurai S Dhandapany
- Centre for Cardiovascular Biology and Disease, Institute for Stem Cell Biology and Regenerative Medicine (inStem), Bangalore, India
- The Knight Cardiovascular Institute, Oregon Health and Science University, Portland, OR, USA
- Department of Medicine, Oregon Health and Science University, Portland, OR, USA
- Department of Molecular and Medical Genetics, Oregon Health and Science University, Portland, OR, USA
| | - Richard C Becker
- Division of Cardiovascular Health and Disease, Department of Internal Medicine, Heart, Lung and Vascular Institute, University of Cincinnati, College of Medicine, 231 Albert Sabin Way, Cincinnati, OH, 45267-0575, USA
| | - Evangelia G Kranias
- Department of Pharmacology and Systems Physiology, University of Cincinnati, College of Medicine, Cincinnati, OH, 45267, USA
| | - Sakthivel Sadayappan
- Division of Cardiovascular Health and Disease, Department of Internal Medicine, Heart, Lung and Vascular Institute, University of Cincinnati, College of Medicine, 231 Albert Sabin Way, Cincinnati, OH, 45267-0575, USA
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14
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Sarkar SS, Trivedi DV, Morck MM, Adhikari AS, Pasha SN, Ruppel KM, Spudich JA. The hypertrophic cardiomyopathy mutations R403Q and R663H increase the number of myosin heads available to interact with actin. SCIENCE ADVANCES 2020; 6:eaax0069. [PMID: 32284968 PMCID: PMC7124958 DOI: 10.1126/sciadv.aax0069] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2019] [Accepted: 01/09/2020] [Indexed: 05/20/2023]
Abstract
Hypertrophic cardiomyopathy (HCM) mutations in β-cardiac myosin and myosin binding protein-C (MyBP-C) lead to hypercontractility of the heart, an early hallmark of HCM. We show that hypercontractility caused by the HCM-causing mutation R663H cannot be explained by changes in fundamental myosin contractile parameters, much like the HCM-causing mutation R403Q. Using enzymatic assays with purified human β-cardiac myosin, we provide evidence that both mutations cause hypercontractility by increasing the number of functionally accessible myosin heads. We also demonstrate that the myosin mutation R403Q, but not R663H, ablates the binding of myosin with the C0-C7 fragment of MyBP-C. Furthermore, addition of C0-C7 decreases the wild-type myosin basal ATPase single turnover rate, while the mutants do not show a similar reduction. These data suggest that a primary mechanism of action for these mutations is to increase the number of myosin heads functionally available for interaction with actin, which could contribute to hypercontractility.
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Affiliation(s)
- Saswata S. Sarkar
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Darshan V. Trivedi
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Makenna M. Morck
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Arjun S. Adhikari
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Shaik N. Pasha
- National Centre for Biological Sciences (TIFR), GKVK Campus, Bellary Road, Bangalore, India
| | - Kathleen M. Ruppel
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA
- Stanford Cardiovascular Institute, 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
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA 94305, USA
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15
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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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16
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Bunch TA, Kanassatega RS, Lepak VC, Colson BA. Human cardiac myosin-binding protein C restricts actin structural dynamics in a cooperative and phosphorylation-sensitive manner. J Biol Chem 2019; 294:16228-16240. [PMID: 31519753 PMCID: PMC6827302 DOI: 10.1074/jbc.ra119.009543] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Revised: 09/11/2019] [Indexed: 11/20/2022] Open
Abstract
Cardiac myosin-binding protein C (cMyBP-C) is a thick filament-associated protein that influences actin-myosin interactions. cMyBP-C alters myofilament structure and contractile properties in a protein kinase A (PKA) phosphorylation-dependent manner. To determine the effects of cMyBP-C and its phosphorylation on the microsecond rotational dynamics of actin filaments, we attached a phosphorescent probe to F-actin at Cys-374 and performed transient phosphorescence anisotropy (TPA) experiments. Binding of cMyBP-C N-terminal domains (C0-C2) to labeled F-actin reduced rotational flexibility by 20-25°, indicated by increased final anisotropy of the TPA decay. The effects of C0-C2 on actin TPA were highly cooperative (n = ∼8), suggesting that the cMyBP-C N terminus impacts the rotational dynamics of actin spanning seven monomers (i.e. the length of tropomyosin). PKA-mediated phosphorylation of C0-C2 eliminated the cooperative effects on actin flexibility and modestly increased actin rotational rates. Effects of Ser to Asp phosphomimetic substitutions in the M-domain of C0-C2 on actin dynamics only partially recapitulated the phosphorylation effects. C0-C1 (lacking M-domain/C2) similarly exhibited reduced cooperativity, but not as reduced as by phosphorylated C0-C2. These results suggest an important regulatory role of the M-domain in cMyBP-C effects on actin structural dynamics. In contrast, phosphomimetic substitution of the glycogen synthase kinase (GSK3β) site in the Pro/Ala-rich linker of C0-C2 did not significantly affect the TPA results. We conclude that cMyBP-C binding and PKA-mediated phosphorylation can modulate actin dynamics. We propose that these N-terminal cMyBP-C-induced changes in actin dynamics help explain the functional effects of cMyBP-C phosphorylation on actin-myosin interactions.
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Affiliation(s)
- Thomas A Bunch
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, Arizona 85724
| | | | - Victoria C Lepak
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, Arizona 85724
| | - Brett A Colson
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, Arizona 85724
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17
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Viswanathan SK, Puckelwartz MJ, Mehta A, Ramachandra CJA, Jagadeesan A, Fritsche-Danielson R, Bhat RV, Wong P, Kandoi S, Schwanekamp JA, Kuffel G, Pesce LL, Zilliox MJ, Durai UNB, Verma RS, Molokie RE, Suresh DP, Khoury PR, Thomas A, Sanagala T, Tang HC, Becker RC, Knöll R, Shim W, McNally EM, Sadayappan S. Association of Cardiomyopathy With MYBPC3 D389V and MYBPC3Δ25bpIntronic Deletion in South Asian Descendants. JAMA Cardiol 2019; 3:481-488. [PMID: 29641836 DOI: 10.1001/jamacardio.2018.0618] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Importance The genetic variant MYBPC3Δ25bp occurs in 4% of South Asian descendants, with an estimated 100 million carriers worldwide. MYBPC3 Δ25bp has been linked to cardiomyopathy and heart failure. However, the high prevalence of MYBPC3Δ25bp suggests that other stressors act in concert with MYBPC3Δ25bp. Objective To determine whether there are additional genetic factors that contribute to the cardiomyopathic expression of MYBPC3Δ25bp. Design, Setting, andParticipants South Asian individuals living in the United States were screened for MYBPC3Δ25bp, and a subgroup was clinically evaluated using electrocardiograms and echocardiograms at Loyola University, Chicago, Illinois, between January 2015 and July 2016. Main Outcomes and Measures Next-generation sequencing of 174 cardiovascular disease genes was applied to identify additional modifying gene mutations and correlate genotype-phenotype parameters. Cardiomyocytes derived from human-induced pluripotent stem cells were established and examined to assess the role of MYBPC3Δ25bp. Results In this genotype-phenotype study, individuals of South Asian descent living in the United States from both sexes (36.23% female) with a mean population age of 48.92 years (range, 18-84 years) were recruited. Genetic screening of 2401 US South Asian individuals found an MYBPC3Δ25bpcarrier frequency of 6%. A higher frequency of missense TTN variation was found in MYBPC3Δ25bp carriers compared with noncarriers, identifying distinct genetic backgrounds within the MYBPC3Δ25bp carrier group. Strikingly, 9.6% of MYBPC3Δ25bp carriers also had a novel MYBPC3 variant, D389V. Family studies documented D389V was in tandem on the same allele as MYBPC3Δ25bp, and D389V was only seen in the presence of MYBPC3Δ25bp. In contrast to MYBPC3Δ25bp, MYBPC3Δ25bp/D389V was associated with hyperdynamic left ventricular performance (mean [SEM] left ventricular ejection fraction, 66.7 [0.7%]; left ventricular fractional shortening, 36.6 [0.6%]; P < .03) and stem cell-derived cardiomyocytes exhibited cellular hypertrophy with abnormal Ca2+ transients. Conclusions and Relevance MYBPC3Δ25bp/D389V is associated with hyperdynamic features, which are an early finding in hypertrophic cardiomyopathy and thought to reflect an unfavorable energetic state. These findings support that a subset of MYBPC3Δ25bp carriers, those with D389V, account for the increased risk attributed to MYBPC3Δ25bp.
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Affiliation(s)
- Shiv Kumar Viswanathan
- Heart, Lung and Vascular Institute, Department of Internal Medicine, University of Cincinnati, Cincinnati, Ohio.,Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois
| | | | - Ashish Mehta
- National Heart Research Institute Singapore.,Cardiovascular Academic Clinical Program, DUKE-NUS Medical School, Singapore.,PSC and Phenotyping Laboratory, Victor Chang Cardiac Research Institute, Sydney, Australia
| | | | | | - Regina Fritsche-Danielson
- Cardiovascular and Metabolic Disease Innovative Medicines and Early Development Unit, AstraZeneca Research and Development, Gothenburg, Sweden
| | - Ratan V Bhat
- Cardiovascular and Metabolic Disease Innovative Medicines and Early Development Unit, AstraZeneca Research and Development, Gothenburg, Sweden
| | - Philip Wong
- National Heart Research Institute Singapore.,Cardiovascular and Metabolic Disorders Program, DUKE-NUS Medical School, Singapore.,Department of Cardiology, National Heart Centre Singapore, Singapore
| | - Sangeetha Kandoi
- Heart, Lung and Vascular Institute, Department of Internal Medicine, University of Cincinnati, Cincinnati, Ohio.,Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois.,Department of Biotechnology, Indian Institute of Technology Madras, Chennai, Tamilnadu, India
| | - Jennifer A Schwanekamp
- Heart, Lung and Vascular Institute, Department of Internal Medicine, University of Cincinnati, Cincinnati, Ohio
| | - Gina Kuffel
- Department of Public Health Sciences, Loyola University Chicago, Maywood, Illinois
| | - Lorenzo L Pesce
- Computation Institute, The University of Chicago, Chicago, Illinois
| | - Michael J Zilliox
- Department of Public Health Sciences, Loyola University Chicago, Maywood, Illinois
| | - U Nalla B Durai
- Divison of Hematology and Oncology, University of Illinois at Chicago
| | - Rama Shanker Verma
- Department of Biotechnology, Indian Institute of Technology Madras, Chennai, Tamilnadu, India
| | - Robert E Molokie
- Divison of Hematology and Oncology, University of Illinois at Chicago
| | | | - Philip R Khoury
- Heart Institute, Cincinnati Children's Hospital, Cincinnati, Ohio
| | - Annie Thomas
- Marcella Niehoff School of Nursing, Loyola University Chicago, Maywood, Illinois
| | - Thriveni Sanagala
- Department of Cardiology and Echocardiography and Cardiographics, Loyola University Chicago, Maywood, Illinois
| | - Hak Chiaw Tang
- Department of Cardiology, National Heart Centre Singapore, Singapore
| | - Richard C Becker
- Heart, Lung and Vascular Institute, Department of Internal Medicine, University of Cincinnati, Cincinnati, Ohio
| | - Ralph Knöll
- Cardiovascular and Metabolic Disease Innovative Medicines and Early Development Unit, AstraZeneca Research and Development, Gothenburg, Sweden.,Integrated Cardio-Metabolic Centre, Myocardial Genetics, Karolinska Institutet, University Hospital, Heart and Vascular Theme, Stockholm, Sweden
| | - Winston Shim
- National Heart Research Institute Singapore.,Cardiovascular and Metabolic Disorders Program, DUKE-NUS Medical School, Singapore
| | - Elizabeth M McNally
- Center for Genetic Medicine, Northwestern University, Chicago, Illinois.,Associate Editor for Translational Science
| | - Sakthivel Sadayappan
- Heart, Lung and Vascular Institute, Department of Internal Medicine, University of Cincinnati, Cincinnati, Ohio.,Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois
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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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Li CJ, Chen CS, Yiang GT, Tsai APY, Liao WT, Wu MY. Advanced Evolution of Pathogenesis Concepts in Cardiomyopathies. J Clin Med 2019; 8:jcm8040520. [PMID: 30995779 PMCID: PMC6518034 DOI: 10.3390/jcm8040520] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Revised: 04/12/2019] [Accepted: 04/12/2019] [Indexed: 12/15/2022] Open
Abstract
Cardiomyopathy is a group of heterogeneous cardiac diseases that impair systolic and diastolic function, and can induce chronic heart failure and sudden cardiac death. Cardiomyopathy is prevalent in the general population, with high morbidity and mortality rates, and contributes to nearly 20% of sudden cardiac deaths in younger individuals. Genetic mutations associated with cardiomyopathy play a key role in disease formation, especially the mutation of sarcomere encoding genes and ATP kinase genes, such as titin, lamin A/C, myosin heavy chain 7, and troponin T1. Pathogenesis of cardiomyopathy occurs by multiple complex steps involving several pathways, including the Ras-Raf-mitogen-activated protein kinase-extracellular signal-activated kinase pathway, G-protein signaling, mechanotransduction pathway, and protein kinase B/phosphoinositide 3-kinase signaling. Excess biomechanical stress induces apoptosis signaling in cardiomyocytes, leading to cell loss, which can induce myocardial fibrosis and remodeling. The clinical features and pathophysiology of cardiomyopathy are discussed. Although several basic and clinical studies have investigated the mechanism of cardiomyopathy, the detailed pathophysiology remains unclear. This review summarizes current concepts and focuses on the molecular mechanisms of cardiomyopathy, especially in the signaling from mutation to clinical phenotype, with the aim of informing the development of therapeutic interventions.
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Affiliation(s)
- Chia-Jung Li
- Department of Obstetrics and Gynecology, Kaohsiung Veterans General Hospital, Kaohsiung 813, Taiwan.
| | - Chien-Sheng Chen
- Department of Emergency Medicine, Taipei Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, New Taipei 231, Taiwan.
- Department of Emergency Medicine, School of Medicine, Tzu Chi University, Hualien 970, Taiwan.
| | - Giou-Teng Yiang
- Department of Emergency Medicine, Taipei Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, New Taipei 231, Taiwan.
- Department of Emergency Medicine, School of Medicine, Tzu Chi University, Hualien 970, Taiwan.
| | - Andy Po-Yi Tsai
- Department of Medical Research, Buddhist Tzu Chi General Hospital, Hualien 970, Taiwan.
| | - Wan-Ting Liao
- Institute of Medicine, Chung Shan Medical University, Taichung 402, Taiwan.
- Chinese Medicine Department, Show Chwan Memorial Hospital, Changhua 500, Taiwan.
| | - Meng-Yu Wu
- Department of Emergency Medicine, Taipei Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, New Taipei 231, Taiwan.
- Department of Emergency Medicine, School of Medicine, Tzu Chi University, Hualien 970, Taiwan.
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20
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Yotti R, Seidman CE, Seidman JG. Advances in the Genetic Basis and Pathogenesis of Sarcomere Cardiomyopathies. Annu Rev Genomics Hum Genet 2019; 20:129-153. [PMID: 30978303 DOI: 10.1146/annurev-genom-083118-015306] [Citation(s) in RCA: 94] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Hypertrophic cardiomyopathy (HCM) and dilated cardiomyopathy (DCM) are common heart muscle disorders that are caused by pathogenic variants in sarcomere protein genes. HCM is characterized by unexplained cardiac hypertrophy (increased chamber wall thickness) that is accompanied by enhanced cardiac contractility and impaired relaxation. DCM is defined as increased ventricular chamber volume with contractile impairment. In this review, we discuss recent analyses that provide new insights into the molecular mechanisms that cause these conditions. HCM studies have uncovered the critical importance of conformational changes that occur during relaxation and enable energy conservation, which are frequently disturbed by HCM mutations. DCM studies have demonstrated the considerable prevalence of truncating variants in titin and have discerned that these variants reduce contractile function by impairing sarcomerogenesis. These new pathophysiologic mechanisms open exciting opportunities to identify new pharmacological targets and develop future cardioprotective strategies.
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Affiliation(s)
- Raquel Yotti
- Department of Cardiology, Hospital General Universitario Gregorio Marañón, Instituto de Investigación Sanitaria Gregorio Marañón, 28007 Madrid, Spain; .,Centro de Investigación Biomédica en Red en Enfermedades Cardiovasculares (CIBERCV), Instituto de Salud Carlos III, 28029 Madrid, Spain
| | - Christine E Seidman
- Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA; , .,Cardiovascular Division and Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA.,Howard Hughes Medical Institute, Chevy Chase, Maryland 20815, USA
| | - Jonathan G Seidman
- Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA; ,
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21
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Revealing the mechanism of how cardiac myosin-binding protein C N-terminal fragments sensitize thin filaments for myosin binding. Proc Natl Acad Sci U S A 2019; 116:6828-6835. [PMID: 30877248 PMCID: PMC6452674 DOI: 10.1073/pnas.1816480116] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Diverse demands on cardiac muscle require the fine-tuning of contraction. Cardiac myosin binding protein-C (cMyBP-C) is involved in this regulation; however, its precise molecular mechanism of action remains uncertain. By imaging the interactions of single myosin and cMyBP-C molecules interacting with suspended thin filaments in vitro we observe cMyBP-C N-terminal fragments assist activation and modulate contraction velocity by affecting myosin binding to the thin filament. Fluorescent imaging of Cy3-labeled cMyBP-C revealed that it diffusively scans the thin filament and then strongly binds to displace tropomyosin and activate at low calcium. At high calcium, cMyBP-C decorates the filament more extensively, reducing myosin binding through competing with binding sites. Understanding the mechanism of MyBP-C action has important implications for heart disease. Cardiac muscle contraction is triggered by calcium binding to troponin. The consequent movement of tropomyosin permits myosin binding to actin, generating force. Cardiac myosin-binding protein C (cMyBP-C) plays a modulatory role in this activation process. One potential mechanism for the N-terminal domains of cMyBP-C to achieve this is by binding directly to the actin-thin filament at low calcium levels to enhance the movement of tropomyosin. To determine the molecular mechanisms by which cMyBP-C enhances myosin recruitment to the actin-thin filament, we directly visualized fluorescently labeled cMyBP-C N-terminal fragments and GFP-labeled myosin molecules binding to suspended actin-thin filaments in a fluorescence-based single-molecule microscopy assay. Binding of the C0C3 N-terminal cMyBP-C fragment to the thin filament enhanced myosin association at low calcium levels. However, at high calcium levels, C0C3 bound in clusters, blocking myosin binding. Dynamic imaging of thin filament-bound Cy3-C0C3 molecules demonstrated that these fragments diffuse along the thin filament before statically binding, suggesting a mechanism that involves a weak-binding mode to search for access to the thin filament and a tight-binding mode to sensitize the thin filament to calcium, thus enhancing myosin binding. Although shorter N-terminal fragments (Cy3-C0C1 and Cy3-C0C1f) bound to the thin filaments and displayed modes of motion on the thin filament similar to that of the Cy3-C0C3 fragment, the shorter fragments were unable to sensitize the thin filament. Therefore, the longer N-terminal fragment (C0C3) must possess the requisite domains needed to bind specifically to the thin filament in order for the cMyBP-C N terminus to modulate cardiac contractility.
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22
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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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23
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Toepfer CN, Wakimoto H, Garfinkel AC, McDonough B, Liao D, Jiang J, Tai AC, Gorham JM, Lunde IG, Lun M, Lynch TL, McNamara JW, Sadayappan S, Redwood CS, Watkins HC, Seidman JG, Seidman CE. Hypertrophic cardiomyopathy mutations in MYBPC3 dysregulate myosin. Sci Transl Med 2019; 11:eaat1199. [PMID: 30674652 PMCID: PMC7184965 DOI: 10.1126/scitranslmed.aat1199] [Citation(s) in RCA: 120] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Revised: 06/05/2018] [Accepted: 11/30/2018] [Indexed: 12/16/2022]
Abstract
The mechanisms by which truncating mutations in MYBPC3 (encoding cardiac myosin-binding protein C; cMyBPC) or myosin missense mutations cause hypercontractility and poor relaxation in hypertrophic cardiomyopathy (HCM) are incompletely understood. Using genetic and biochemical approaches, we explored how depletion of cMyBPC altered sarcomere function. We demonstrated that stepwise loss of cMyBPC resulted in reciprocal augmentation of myosin contractility. Direct attenuation of myosin function, via a damaging missense variant (F764L) that causes dilated cardiomyopathy (DCM), normalized the increased contractility from cMyBPC depletion. Depletion of cMyBPC also altered dynamic myosin conformations during relaxation, enhancing the myosin state that enables ATP hydrolysis and thin filament interactions while reducing the super relaxed conformation associated with energy conservation. MYK-461, a pharmacologic inhibitor of myosin ATPase, rescued relaxation deficits and restored normal contractility in mouse and human cardiomyocytes with MYBPC3 mutations. These data define dosage-dependent effects of cMyBPC on myosin that occur across the cardiac cycle as the pathophysiologic mechanisms by which MYBPC3 truncations cause HCM. Therapeutic strategies to attenuate cMyBPC activity may rescue depressed cardiac contractility in patients with DCM, whereas inhibiting myosin by MYK-461 should benefit the substantial proportion of patients with HCM with MYBPC3 mutations.
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Affiliation(s)
- Christopher N Toepfer
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA.
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, OX3 9DU, UK
- Wellcome Centre for Human Genetics, University of Oxford, OX3 7BN, UK
| | - Hiroko Wakimoto
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
- Department of Cardiology, Children's Hospital Boston, Boston, MA 02115, USA
| | | | | | - Dan Liao
- Department of Biochemistry and Cardiovascular Research Institute (CVRI), Yong Loo Lin School of Medicine, National University of Singapore, Singapore 119228, Singapore
| | - Jianming Jiang
- Department of Biochemistry and Cardiovascular Research Institute (CVRI), Yong Loo Lin School of Medicine, National University of Singapore, Singapore 119228, Singapore
| | - Angela C Tai
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Joshua M Gorham
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Ida G Lunde
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, 0318 Oslo, Norway
| | - Mingyue Lun
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital, Boston, MA 02115, USA
| | - Thomas L Lynch
- Department of Molecular Pharmacology and Therapeutics, Health Sciences Division, Loyola University Chicago, Maywood, IL 60153, USA
| | - James W McNamara
- Heart, Lung and Vascular Institute, University of Cincinnati, Cincinnati, OH 45219, USA
| | - Sakthivel Sadayappan
- Heart, Lung and Vascular Institute, University of Cincinnati, Cincinnati, OH 45219, USA
| | - Charles S Redwood
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, OX3 9DU, UK
| | - Hugh C Watkins
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, OX3 9DU, UK
- Wellcome Centre for Human Genetics, University of Oxford, OX3 7BN, UK
| | | | - Christine E Seidman
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA.
- Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA
- Division of Cardiovascular Medicine, Brigham and Women's Hospital, Boston, MA 02115, USA
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24
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Hypertrophic cardiomyopathy-linked variants of cardiac myosin-binding protein C3 display altered molecular properties and actin interaction. Biochem J 2018; 475:3933-3948. [PMID: 30446606 DOI: 10.1042/bcj20180685] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2018] [Revised: 11/14/2018] [Accepted: 11/15/2018] [Indexed: 12/31/2022]
Abstract
The most common inherited cardiac disorder, hypertrophic cardiomyopathy (HCM), is characterized by thickening of heart muscle, for which genetic mutations in cardiac myosin-binding protein C3 (c-MYBPC3) gene, is the leading cause. Notably, patients with HCM display a heterogeneous clinical presentation, onset and prognosis. Thus, delineating the molecular mechanisms that explain how disparate c-MYBPC3 variants lead to HCM is essential for correlating the impact of specific genotypes on clinical severity. Herein, five c-MYBPC3 missense variants clinically associated with HCM were investigated; namely V1 (R177H), V2 (A216T), V3 (E258K), V4 (E441K) and double mutation V5 (V3 + V4), all located within the C1 and C2 domains of MyBP-C, a region known to interact with sarcomeric protein, actin. Injection of the variant complementary RNAs in zebrafish embryos was observed to recapitulate phenotypic aspects of HCM in patients. Interestingly, V3- and V5-cRNA injection produced the most severe zebrafish cardiac phenotype, exhibiting increased diastolic/systolic myocardial thickness and significantly reduced heart rate compared with control zebrafish. Molecular analysis of recombinant C0-C2 protein fragments revealed that c-MYBPC3 variants alter the C0-C2 domain secondary structure, thermodynamic stability and importantly, result in a reduced binding affinity to cardiac actin. V5 (double mutant), displayed the greatest protein instability with concomitant loss of actin-binding function. Our study provides specific mechanistic insight into how c-MYBPC3 pathogenic variants alter both functional and structural characteristics of C0-C2 domains leading to impaired actin interaction and reduced contractility, which may provide a basis for elucidating the disease mechanism in HCM patients with c- MYBPC3 mutations.
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25
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Li KL, Methawasin M, Tanner BCW, Granzier HL, Solaro RJ, Dong WJ. Sarcomere length-dependent effects on Ca 2+-troponin regulation in myocardium expressing compliant titin. J Gen Physiol 2018; 151:30-41. [PMID: 30523116 PMCID: PMC6314383 DOI: 10.1085/jgp.201812218] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Accepted: 11/01/2018] [Indexed: 11/20/2022] Open
Abstract
Increases in sarcomere length cause enhanced force generation in cardiomyocytes by an unknown mechanism. Li et al. reveal that titin-based passive tension contributes to length-dependent activation of myofilaments and that tightly bound myosin–actin cross-bridges are associated with this effect. Cardiac performance is tightly regulated at the cardiomyocyte level by sarcomere length, such that increases in sarcomere length lead to sharply enhanced force generation at the same Ca2+ concentration. Length-dependent activation of myofilaments involves dynamic and complex interactions between a multitude of thick- and thin-filament components. Among these components, troponin, myosin, and the giant protein titin are likely to be key players, but the mechanism by which these proteins are functionally linked has been elusive. Here, we investigate this link in the mouse myocardium using in situ FRET techniques. Our objective was to monitor how length-dependent Ca2+-induced conformational changes in the N domain of cardiac troponin C (cTnC) are modulated by myosin–actin cross-bridge (XB) interactions and increased titin compliance. We reconstitute FRET donor- and acceptor-modified cTnC(13C/51C)AEDANS-DDPM into chemically skinned myocardial fibers from wild-type and RBM20-deletion mice. The Ca2+-induced conformational changes in cTnC are quantified and characterized using time-resolved FRET measurements as XB state and sarcomere length are varied. The RBM20-deficient mouse expresses a more compliant N2BA titin isoform, leading to reduced passive tension in the myocardium. This provides a molecular tool to investigate how altered titin-based passive tension affects Ca2+-troponin regulation in response to mechanical stretch. In wild-type myocardium, we observe a direct association of sarcomere length–dependent enhancement of troponin regulation with both Ca2+ activation and strongly bound XB states. In comparison, measurements from titin RBM20-deficient animals show blunted sarcomere length–dependent effects. These results suggest that titin-based passive tension contributes to sarcomere length–dependent Ca2+-troponin regulation. We also conclude that strong XB binding plays an important role in linking the modulatory effect of titin compliance to Ca2+-troponin regulation of the myocardium.
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Affiliation(s)
- King-Lun Li
- Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, WA
| | - Mei Methawasin
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ
| | - Bertrand C W Tanner
- Integrative Physiology and Neuroscience, Washington State University, Pullman, WA
| | - Henk L Granzier
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ
| | - R John Solaro
- The Department of Physiology and Biophysics, Center for Cardiovascular Research, College of Medicine, University of Illinois at Chicago, Chicago, IL
| | - Wen-Ji Dong
- Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, WA .,Integrative Physiology and Neuroscience, Washington State University, Pullman, WA
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26
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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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27
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Calcium-Dependent Interaction Occurs between Slow Skeletal Myosin Binding Protein C and Calmodulin. MAGNETOCHEMISTRY 2017. [DOI: 10.3390/magnetochemistry4010001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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28
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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: 57] [Impact Index Per Article: 8.1] [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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29
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Gresham KS, Mamidi R, Li J, Kwak H, Stelzer JE. Sarcomeric protein modification during adrenergic stress enhances cross-bridge kinetics and cardiac output. J Appl Physiol (1985) 2016; 122:520-530. [PMID: 27909224 DOI: 10.1152/japplphysiol.00306.2016] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Revised: 10/21/2016] [Accepted: 11/23/2016] [Indexed: 12/23/2022] Open
Abstract
Molecular adaptations to chronic neurohormonal stress, including sarcomeric protein cleavage and phosphorylation, provide a mechanism to increase ventricular contractility and enhance cardiac output, yet the link between sarcomeric protein modifications and changes in myocardial function remains unclear. To examine the effects of neurohormonal stress on posttranslational modifications of sarcomeric proteins, mice were administered combined α- and β-adrenergic receptor agonists (isoproterenol and phenylephrine, IPE) for 14 days using implantable osmotic pumps. In addition to significant cardiac hypertrophy and increased maximal ventricular pressure, IPE treatment accelerated pressure development and relaxation (74% increase in dP/dtmax and 14% decrease in τ), resulting in a 52% increase in cardiac output compared with saline (SAL)-treated mice. Accelerated pressure development was maintained when accounting for changes in heart rate and preload, suggesting that myocardial adaptations contribute to enhanced ventricular contractility. Ventricular myocardium isolated from IPE-treated mice displayed a significant reduction in troponin I (TnI) and myosin-binding protein C (MyBP-C) expression and a concomitant increase in the phosphorylation levels of the remaining TnI and MyBP-C protein compared with myocardium isolated from saline-treated control mice. Skinned myocardium isolated from IPE-treated mice displayed a significant acceleration in the rate of cross-bridge (XB) detachment (46% increase) and an enhanced magnitude of XB recruitment (43% increase) at submaximal Ca2+ activation compared with SAL-treated mice but unaltered myofilament Ca2+ sensitivity of force generation. These findings demonstrate that sarcomeric protein modifications during neurohormonal stress are molecular adaptations that enhance in vivo ventricular contractility through accelerated XB kinetics to increase cardiac output.NEW & NOTEWORTHY Posttranslational modifications to sarcomeric regulatory proteins provide a mechanism to modulate cardiac function in response to stress. In this study, we demonstrate that neurohormonal stress produces modifications to myosin-binding protein C and troponin I, including a reduction in protein expression within the sarcomere and increased phosphorylation of the remaining protein, which serve to enhance cross-bridge kinetics and increase cardiac output. These findings highlight the importance of sarcomeric regulatory protein modifications in modulating ventricular function during cardiac stress.
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Affiliation(s)
- Kenneth S Gresham
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, Ohio
| | - Ranganath Mamidi
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, Ohio
| | - Jiayang Li
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, Ohio
| | - Hyerin Kwak
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, Ohio
| | - Julian E Stelzer
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, Ohio
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30
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Spudich JA, Aksel T, Bartholomew SR, Nag S, Kawana M, Yu EC, Sarkar SS, Sung J, Sommese RF, Sutton S, Cho C, Adhikari AS, Taylor R, Liu C, Trivedi D, Ruppel KM. Effects of hypertrophic and dilated cardiomyopathy mutations on power output by human β-cardiac myosin. ACTA ACUST UNITED AC 2016; 219:161-7. [PMID: 26792326 DOI: 10.1242/jeb.125930] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Hypertrophic cardiomyopathy is the most frequently occurring inherited cardiovascular disease, with a prevalence of more than one in 500 individuals worldwide. Genetically acquired dilated cardiomyopathy is a related disease that is less prevalent. Both are caused by mutations in the genes encoding the fundamental force-generating protein machinery of the cardiac muscle sarcomere, including human β-cardiac myosin, the motor protein that powers ventricular contraction. Despite numerous studies, most performed with non-human or non-cardiac myosin, there is no clear consensus about the mechanism of action of these mutations on the function of human β-cardiac myosin. We are using a recombinantly expressed human β-cardiac myosin motor domain along with conventional and new methodologies to characterize the forces and velocities of the mutant myosins compared with wild type. Our studies are extending beyond myosin interactions with pure actin filaments to include the interaction of myosin with regulated actin filaments containing tropomyosin and troponin, the roles of regulatory light chain phosphorylation on the functions of the system, and the possible roles of myosin binding protein-C and titin, important regulatory components of both cardiac and skeletal muscles.
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Affiliation(s)
- James A Spudich
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Tural Aksel
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Sadie R Bartholomew
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Suman Nag
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Masataka Kawana
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Elizabeth Choe Yu
- 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
| | - Jongmin Sung
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Ruth F Sommese
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Shirley Sutton
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Carol Cho
- 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
| | - Rebecca Taylor
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Chao Liu
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Darshan Trivedi
- 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
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31
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Bhuiyan MS, McLendon P, James J, Osinska H, Gulick J, Bhandary B, Lorenz JN, Robbins J. In vivo definition of cardiac myosin-binding protein C's critical interactions with myosin. Pflugers Arch 2016; 468:1685-95. [PMID: 27568194 DOI: 10.1007/s00424-016-1873-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2016] [Accepted: 08/22/2016] [Indexed: 12/13/2022]
Abstract
Cardiac myosin-binding protein C (cMyBP-C) is an integral part of the sarcomeric machinery in cardiac muscle that enables normal function. cMyBP-C regulates normal cardiac contraction by functioning as a brake through interactions with the sarcomere's thick, thin, and titin filaments. cMyBP-C's precise effects as it binds to the different filament systems remain obscure, particularly as it impacts on the myosin heavy chain's head domain, contained within the subfragment 2 (S2) region. This portion of the myosin heavy chain also contains the ATPase activity critical for myosin's function. Mutations in myosin's head, as well as in cMyBP-C, are a frequent cause of familial hypertrophic cardiomyopathy (FHC). We generated transgenic lines in which endogenous cMyBP-C was replaced by protein lacking the residues necessary for binding to S2 (cMyBP-C(S2-)). We found, surprisingly, that cMyBP-C lacking the S2 binding site is incorporated normally into the sarcomere, although systolic function is compromised. We show for the first time the acute and chronic in vivo consequences of ablating a filament-specific interaction of cMyBP-C. This work probes the functional consequences, in the whole animal, of modifying a critical structure-function relationship, the protein's ability to bind to a region of the critical enzyme responsible for muscle contraction, the subfragment 2 domain of the myosin heavy chain. We show that the binding is not critical for the protein's correct insertion into the sarcomere's architecture, but is essential for long-term, normal function in the physiological context of the heart.
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Affiliation(s)
- Md Shenuarin Bhuiyan
- Department of Pediatrics, Division of Molecular Cardiovascular Biology, The Heart Institute, Cincinnati Children's Hospital Medical Center, MLC 7020, 240 Albert Sabin Way, Cincinnati, OH, 45229, USA.,Department of Pathology and Translational Pathobiology, Louisiana State University Health Sciences Center, Shreveport, LA, USA
| | - Patrick McLendon
- Department of Pediatrics, Division of Molecular Cardiovascular Biology, The Heart Institute, Cincinnati Children's Hospital Medical Center, MLC 7020, 240 Albert Sabin Way, Cincinnati, OH, 45229, USA
| | - Jeanne James
- Department of Pediatrics, Division of Molecular Cardiovascular Biology, The Heart Institute, Cincinnati Children's Hospital Medical Center, MLC 7020, 240 Albert Sabin Way, Cincinnati, OH, 45229, USA
| | - Hanna Osinska
- Department of Pediatrics, Division of Molecular Cardiovascular Biology, The Heart Institute, Cincinnati Children's Hospital Medical Center, MLC 7020, 240 Albert Sabin Way, Cincinnati, OH, 45229, USA
| | - James Gulick
- Department of Pediatrics, Division of Molecular Cardiovascular Biology, The Heart Institute, Cincinnati Children's Hospital Medical Center, MLC 7020, 240 Albert Sabin Way, Cincinnati, OH, 45229, USA
| | - Bidur Bhandary
- Department of Pediatrics, Division of Molecular Cardiovascular Biology, The Heart Institute, Cincinnati Children's Hospital Medical Center, MLC 7020, 240 Albert Sabin Way, Cincinnati, OH, 45229, USA
| | - John N Lorenz
- Department of Molecular and Cellular Physiology (J.N.L.), University of Cincinnati College of Medicine, Cincinnati, OH, 45267, USA
| | - Jeffrey Robbins
- Department of Pediatrics, Division of Molecular Cardiovascular Biology, The Heart Institute, Cincinnati Children's Hospital Medical Center, MLC 7020, 240 Albert Sabin Way, Cincinnati, OH, 45229, USA.
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32
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Yu H, Chakravorty S, Song W, Ferenczi MA. Phosphorylation of the regulatory light chain of myosin in striated muscle: methodological perspectives. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2016; 45:779-805. [PMID: 27084718 PMCID: PMC5101276 DOI: 10.1007/s00249-016-1128-z] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Revised: 03/10/2016] [Accepted: 03/23/2016] [Indexed: 12/18/2022]
Abstract
Phosphorylation of the regulatory light chain (RLC) of myosin modulates cellular functions such as muscle contraction, mitosis, and cytokinesis. Phosphorylation defects are implicated in a number of diseases. Here we focus on striated muscle where changes in RLC phosphorylation relate to diseases such as hypertrophic cardiomyopathy and muscular dystrophy, or age-related changes. RLC phosphorylation in smooth muscle and non-muscle cells are covered briefly where relevant. There is much scientific interest in controlling the phosphorylation levels of RLC in vivo and in vitro in order to understand its physiological function in striated muscles. A summary of available and emerging in vivo and in vitro methods is presented. The physiological role of RLC phosphorylation and novel pathways are discussed to highlight the differences between muscle types and to gain insights into disease processes.
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Affiliation(s)
- Haiyang Yu
- Lee Kong Chian School of Medicine, Nanyang Technological University, Experimental Medicine Building, Level 3, 59 Nanyang Drive, Singapore, 636921, Singapore
| | - Samya Chakravorty
- Lee Kong Chian School of Medicine, Nanyang Technological University, Experimental Medicine Building, Level 3, 59 Nanyang Drive, Singapore, 636921, Singapore
| | - Weihua Song
- Lee Kong Chian School of Medicine, Nanyang Technological University, Experimental Medicine Building, Level 3, 59 Nanyang Drive, Singapore, 636921, Singapore
| | - Michael A Ferenczi
- Lee Kong Chian School of Medicine, Nanyang Technological University, Experimental Medicine Building, Level 3, 59 Nanyang Drive, Singapore, 636921, Singapore.
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33
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Mun JY, Kensler RW, Harris SP, Craig R. The cMyBP-C HCM variant L348P enhances thin filament activation through an increased shift in tropomyosin position. J Mol Cell Cardiol 2015; 91:141-7. [PMID: 26718724 DOI: 10.1016/j.yjmcc.2015.12.014] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2015] [Revised: 12/08/2015] [Accepted: 12/18/2015] [Indexed: 10/22/2022]
Abstract
Mutations in cardiac myosin binding protein C (cMyBP-C), a thick filament protein that modulates contraction of the heart, are a leading cause of hypertrophic cardiomyopathy (HCM). Electron microscopy and 3D reconstruction of thin filaments decorated with cMyBP-C N-terminal fragments suggest that one mechanism of this modulation involves the interaction of cMyBP-C's N-terminal domains with thin filaments to enhance their Ca(2+)-sensitivity by displacement of tropomyosin from its blocked (low Ca(2+)) to its closed (high Ca(2+)) position. The extent of this tropomyosin shift is reduced when cMyBP-C N-terminal domains are phosphorylated. In the current study, we have examined L348P, a sequence variant of cMyBP-C first identified in a screen of patients with HCM. In L348P, leucine 348 is replaced by proline in cMyBP-C's regulatory M-domain, resulting in an increase in cMyBP-C's ability to enhance thin filament Ca(2+)-sensitization. Our goal here was to determine the structural basis for this enhancement by carrying out 3D reconstruction of thin filaments decorated with L348P-mutant cMyBP-C. When thin filaments were decorated with wild type N-terminal domains at low Ca(2+), tropomyosin moved from the blocked to the closed position, as found previously. In contrast, the L348P mutant caused a significantly larger tropomyosin shift, to approximately the open position, consistent with its enhancement of Ca(2+)-sensitization. Phosphorylated wild type fragments showed a smaller shift than unphosphorylated fragments, whereas the shift induced by the L348P mutant was not affected by phosphorylation. We conclude that the L348P mutation causes a gain of function by enhancing tropomyosin displacement on the thin filament in a phosphorylation-independent way.
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Affiliation(s)
- Ji Young Mun
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, MA 01655, USA
| | - Robert W Kensler
- Department of Anatomy and Neurobiology, University of Puerto Rico School of Medicine, San Juan, PR 00936, USA
| | - Samantha P Harris
- Department of Cellular and Molecular Medicine, University of Arizona College of Medicine, Tucson, AZ 85724, USA
| | - Roger Craig
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, MA 01655, USA.
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34
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The myosin mesa and a possible unifying hypothesis for the molecular basis of human hypertrophic cardiomyopathy. Biochem Soc Trans 2015; 43:64-72. [PMID: 25619247 DOI: 10.1042/bst20140324] [Citation(s) in RCA: 90] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
No matter how many times one explores the structure of the myosin molecule, there is always something new to discover. Here, I describe the myosin mesa, a structural feature of the motor domain that has the characteristics of a binding domain for another protein, possibly myosin-binding protein C (MyBP-C). Interestingly, many well-known hypertrophic cardiomyopathy (HCM) mutations lie along this surface and may affect the putative interactions proposed here. A potential unifying hypothesis for the molecular basis of human hypertrophic cardiomyopathy is discussed here. It involves increased power output of the cardiac muscle as a result of HCM mutations causing the release of inhibition by myosin binding protein C.
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Abstract
Heart failure is highly influenced by heritability, and nearly 100 genes link to familial cardiomyopathy. Despite the marked genetic diversity that underlies these complex cardiovascular phenotypes, several key genes and pathways have emerged. Hypertrophic cardiomyopathy is characterized by increased contractility and a greater energetic cost of cardiac output. Dilated cardiomyopathy is often triggered by mutations that disrupt the giant protein titin. The energetic consequences of these mutations offer molecular targets and opportunities for new drug development and gene correction therapies.
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Affiliation(s)
- Elizabeth M McNally
- Center for Genetic Medicine, Northwestern University, Chicago, IL 60611, USA.
| | - David Y Barefield
- Center for Genetic Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Megan J Puckelwartz
- Center for Genetic Medicine, Northwestern University, Chicago, IL 60611, USA
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36
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Luther PK, Craig R. Modulation of striated muscle contraction by binding of myosin binding protein C to actin. BIOARCHITECTURE 2014; 1:277-283. [PMID: 22545180 PMCID: PMC3337130 DOI: 10.4161/bioa.1.6.19341] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Myosin binding protein C (MyBP-C or C-protein) is a protein of the thick (myosin-containing) filaments of striated muscle thought to be involved in the modulation of cardiac contraction in response to β-adrenergic stimulation. The mechanism of this modulation is unknown, but one possibility is through transient binding of the N-terminal end of MyBP-C to the thin (actin-containing) filaments. While such binding has been demonstrated in vitro, it was not known until recently whether such a link between thick and thin filaments also occurred in vivo. Here we review a recent paper in which electron microscopy (EM) is used to directly demonstrate MyBP-C links between myosin and actin filaments in the intact sarcomere, suggesting a possible physical mechanism for modulating filament sliding. Molecular details of MyBP-C binding to actin have recently been elucidated by EM of isolated filaments: the results suggest that MyBP-C might contribute to the modulation of contraction in part by competing with tropomyosin for binding sites on actin. New results on the structure and dynamics of the MyBP-C molecule provide additional insights into the function of this enigmatic molecule.
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37
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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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38
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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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39
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González-Solá M, Al-Khayat HA, Behra M, Kensler RW. Zebrafish cardiac muscle thick filaments: isolation technique and three-dimensional structure. Biophys J 2014; 106:1671-80. [PMID: 24739166 PMCID: PMC4008832 DOI: 10.1016/j.bpj.2014.01.050] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Revised: 01/07/2014] [Accepted: 01/10/2014] [Indexed: 12/11/2022] Open
Abstract
To understand how mutations in thick filament proteins such as cardiac myosin binding protein-C or titin, cause familial hypertrophic cardiomyopathies, it is important to determine the structure of the cardiac thick filament. Techniques for the genetic manipulation of the zebrafish are well established and it has become a major model for the study of the cardiovascular system. Our goal is to develop zebrafish as an alternative system to the mammalian heart model for the study of the structure of the cardiac thick filaments and the proteins that form it. We have successfully isolated thick filaments from zebrafish cardiac muscle, using a procedure similar to those for mammalian heart, and analyzed their structure by negative-staining and electron microscopy. The isolated filaments appear well ordered with the characteristic 42.9 nm quasi-helical repeat of the myosin heads expected from x-ray diffraction. We have performed single particle image analysis on the collected electron microscopy images for the C-zone region of these filaments and obtained a three-dimensional reconstruction at 3.5 nm resolution. This reconstruction reveals structure similar to the mammalian thick filament, and demonstrates that zebrafish may provide a useful model for the study of the changes in the cardiac thick filament associated with disease processes.
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Affiliation(s)
- Maryví González-Solá
- Department of Anatomy and Neurobiology, University of Puerto Rico Medical School, San Juan, Puerto Rico.
| | - Hind A Al-Khayat
- National Heart and Lung Institute, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Martine Behra
- Department of Anatomy and Neurobiology, University of Puerto Rico Medical School, San Juan, Puerto Rico
| | - Robert W Kensler
- Department of Anatomy and Neurobiology, University of Puerto Rico Medical School, San Juan, Puerto Rico
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40
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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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41
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Witayavanitkul N, Ait Mou Y, Kuster DWD, Khairallah RJ, Sarkey J, Govindan S, Chen X, Ge Y, Rajan S, Wieczorek DF, Irving T, Westfall MV, de Tombe PP, Sadayappan S. Myocardial infarction-induced N-terminal fragment of cardiac myosin-binding protein C (cMyBP-C) impairs myofilament function in human myocardium. J Biol Chem 2014; 289:8818-27. [PMID: 24509847 PMCID: PMC3979389 DOI: 10.1074/jbc.m113.541128] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Myocardial infarction (MI) is associated with depressed cardiac contractile function and progression to heart failure. Cardiac myosin-binding protein C, a cardiac-specific myofilament protein, is proteolyzed post-MI in humans, which results in an N-terminal fragment, C0-C1f. The presence of C0-C1f in cultured cardiomyocytes results in decreased Ca2+ transients and cell shortening, abnormalities sufficient for the induction of heart failure in a mouse model. However, the underlying mechanisms remain unclear. Here, we investigate the association between C0-C1f and altered contractility in human cardiac myofilaments in vitro. To accomplish this, we generated recombinant human C0-C1f (hC0C1f) and incorporated it into permeabilized human left ventricular myocardium. Mechanical properties were studied at short (2 μm) and long (2.3 μm) sarcomere length (SL). Our data demonstrate that the presence of hC0C1f in the sarcomere had the greatest effect at short, but not long, SL, decreasing maximal force and myofilament Ca2+ sensitivity. Moreover, hC0C1f led to increased cooperative activation, cross-bridge cycling kinetics, and tension cost, with greater effects at short SL. We further established that the effects of hC0C1f occur through direct interaction with actin and α-tropomyosin. Our data demonstrate that the presence of hC0C1f in the sarcomere is sufficient to induce depressed myofilament function and Ca2+ sensitivity in otherwise healthy human donor myocardium. Decreased cardiac function post-MI may result, in part, from the ability of hC0C1f to bind actin and α-tropomyosin, suggesting that cleaved C0-C1f could act as a poison polypeptide and disrupt the interaction of native cardiac myosin-binding protein C with the thin filament.
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Affiliation(s)
- Namthip Witayavanitkul
- From the Department of Cell and Molecular Physiology, Health Sciences Division, Loyola University Chicago, Maywood, Illinois 60153
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42
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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: 107] [Impact Index Per Article: 10.7] [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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43
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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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44
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Karsai Á, Kellermayer MSZ, Harris SP. Cross-species mechanical fingerprinting of cardiac myosin binding protein-C. Biophys J 2014; 104:2465-75. [PMID: 23746519 DOI: 10.1016/j.bpj.2013.04.027] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Revised: 01/19/2013] [Accepted: 04/08/2013] [Indexed: 01/22/2023] Open
Abstract
Cardiac myosin binding protein-C (cMyBP-C) is a member of the immunoglobulin (Ig) superfamily of proteins and consists of 8 Ig- and 3 fibronectin III (FNIII)-like domains along with a unique regulatory sequence referred to as the MyBP-C motif or M-domain. We previously used atomic force microscopy to investigate the mechanical properties of murine cMyBP-C expressed using a baculovirus/insect cell expression system. Here, we investigate whether the mechanical properties of cMyBP-C are conserved across species by using atomic force microscopy to manipulate recombinant human cMyBP-C and native cMyBP-C purified from bovine heart. Force versus extension data obtained in velocity-clamp experiments showed that the mechanical response of the human recombinant protein was remarkably similar to that of the bovine native cMyBP-C. Ig/Fn-like domain unfolding events occurred in a hierarchical fashion across a threefold range of forces starting at relatively low forces of ~50 pN and ending with the unfolding of the highest stability domains at ~180 pN. Force-extension traces were also frequently marked by the appearance of anomalous force drops suggestive of additional mechanical complexity such as structural coupling among domains. Both recombinant and native cMyBP-C exhibited a prominent segment ~100 nm-long that could be stretched by forces <50 pN before the unfolding of Ig- and FN-like domains. Combined with our previous observations of mouse cMyBP-C, these results establish that although the response of cMyBP-C to mechanical load displays a complex pattern, it is highly conserved across species.
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Affiliation(s)
- Árpád Karsai
- University of California - Davis, Davis, CA, USA
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45
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Reconditi M, Brunello E, Fusi L, Linari M, Martinez MF, Lombardi V, Irving M, Piazzesi G. Sarcomere-length dependence of myosin filament structure in skeletal muscle fibres of the frog. J Physiol 2013; 592:1119-37. [PMID: 24344169 DOI: 10.1113/jphysiol.2013.267849] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
X-ray diffraction patterns were recorded at beamline ID02 of the European Synchrotron Radiation Facility from small bundles of skeletal muscle fibres from Rana esculenta at sarcomere lengths between 2.1 and 3.5 μm at 4°C. The intensities of the X-ray reflections from resting fibres associated with the quasi-helical order of the myosin heads and myosin binding protein C (MyBP-C) decreased in the sarcomere length range 2.6-3.0 μm but were constant outside it, suggesting that an OFF conformation of the thick filament is maintained by an interaction between MyBP-C and the thin filaments. During active isometric contraction the intensity of the M3 reflection from the regular repeat of the myosin heads along the filaments decreased in proportion to the overlap between thick and thin filaments, with no change in its interference fine structure. Thus, myosin heads in the regions of the thick filaments that do not overlap with thin filaments are highly disordered during isometric contraction, in contrast to their quasi-helical order at rest. Heads in the overlap region that belong to two-headed myosin molecules that are fully detached from actin are also highly disordered, in contrast to the detached partners of actin-attached heads. These results provide strong support for the concept of a regulatory structural transition in the thick filament involving changes in both the organisation of the myosin heads on its surface and the axial periodicity of the myosin tails in its backbone, mediated by an interaction between MyBP-C and the thin filaments.
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Affiliation(s)
- Massimo Reconditi
- Randall Division of Cell and Molecular Biophysics, King's College London, London SE1 1UL, UK.
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46
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Patel BG, Wilder T, Solaro RJ. Novel control of cardiac myofilament response to calcium by S-glutathionylation at specific sites of myosin binding protein C. Front Physiol 2013; 4:336. [PMID: 24312057 PMCID: PMC3834529 DOI: 10.3389/fphys.2013.00336] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2013] [Accepted: 11/01/2013] [Indexed: 12/31/2022] Open
Abstract
Our previous studies demonstrated a relation between glutathionylation of cardiac myosin binding protein C (cMyBP-C) and diastolic dysfunction in a hypertensive mouse model stressed by treatment with salt, deoxycorticosterone acetate, and unilateral nephrectomy. Although these results strongly indicated an important role for S-glutathionylation of myosin binding protein C as a modifier of myofilament function, indirect effects of other post-translational modifications may have occurred. Moreover, we did not determine the sites of thiol modification by glutathionylation. To address these issues, we developed an in vitro method to mimic the in situ S-glutathionylation of myofilament proteins and determined direct functional effects and sites of oxidative modification employing Western blotting and mass spectrometry. We induced glutathionylation in vitro by treatment of isolated myofibrils and detergent extracted fiber bundles (skinned fibers) with oxidized glutathione (GSSG). Immuno-blotting results revealed increased glutathionylation with GSSG treatment of a protein band around 140 kDa. Using tandem mass spectrometry, we identified the 140 kDa band as cMyBP-C and determined the sites of glutathionylation to be at cysteines 655, 479, and 627. Determination of the relation between Ca2+-activation of myofibrillar acto-myosin ATPase rate demonstrated an increased Ca2+-sensitivity induced by the S-glutathionylation. Force generating skinned fiber bundles also showed an increase in Ca-sensitivity when treated with oxidized glutathione, which was reversed with the reducing agent, dithiothreitol (DTT). Our data demonstrate that a specific and direct effect of S-glutathionylation of myosin binding protein C is a significant increase in myofilament Ca2+-sensitivity. Our data also provide new insights into the functional significance of oxidative modification of myosin binding protein C and the potential role of domains not previously considered to be functionally significant as controllers of myofilament Ca2+-responsiveness and dynamics.
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Affiliation(s)
- Bindiya G Patel
- Department of Physiology and Biophysics and Center for Cardiovascular Research, College of Medicine, University of Illinois at Chicago Chicago, IL USA
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Michalek AJ, Howarth JW, Gulick J, Previs MJ, Robbins J, Rosevear PR, Warshaw DM. Phosphorylation modulates the mechanical stability of the cardiac myosin-binding protein C motif. Biophys J 2013; 104:442-52. [PMID: 23442866 DOI: 10.1016/j.bpj.2012.12.021] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2012] [Revised: 12/12/2012] [Accepted: 12/14/2012] [Indexed: 01/21/2023] Open
Abstract
Cardiac myosin-binding protein C (cMyBP-C) is a thick-filament-associated protein that modulates cardiac contractility through interactions of its N-terminal immunoglobulin (Ig)-like C0-C2 domains with actin and/or myosin. These interactions are modified by the phosphorylation of at least four serines located within the motif linker between domains C1 and C2. We investigated whether motif phosphorylation alters its mechanical properties by characterizing force-extension relations using atomic force spectroscopy of expressed mouse N-terminal cMyBP-C fragments (i.e., C0-C3). Protein kinase A phosphorylation or serine replacement with aspartic acids did not affect persistence length (0.43 ± 0.04 nm), individual Ig-like domain unfolding forces (118 ± 3 pN), or Ig extension due to unfolding (30 ± 0.38 nm). However, phosphorylation did significantly decrease the C0-C3 mean contour length by 24 ± 2 nm. These results suggest that upon phosphorylation, the motif, which is freely extensible in the nonphosphorylated state, adopts a more stable and/or different structure. Circular dichroism and dynamic light scattering data for shorter expressed C1-C2 fragments with all four serines replaced by aspartic acids confirmed that the motif did adopt a more stable structure that was not apparent in the nonphosphorylated motif. These biophysical data provide both a mechanical and structural basis for cMyBP-C regulation by motif phosphorylation.
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Affiliation(s)
- Arthur J Michalek
- Department of Molecular Physiology and Biophysics, University of Vermont, Burlington, Vermont, USA
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48
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de Lange WJ, Grimes AC, Hegge LF, Ralphe JC. Ablation of cardiac myosin-binding protein-C accelerates contractile kinetics in engineered cardiac tissue. ACTA ACUST UNITED AC 2013; 141:73-84. [PMID: 23277475 PMCID: PMC3536521 DOI: 10.1085/jgp.201210837] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Hypertrophic cardiomyopathy (HCM) caused by mutations in cardiac myosin–binding protein-C (cMyBP-C) is a heterogenous disease in which the phenotypic presentation is influenced by genetic, environmental, and developmental factors. Though mouse models have been used extensively to study the contractile effects of cMyBP-C ablation, early postnatal hypertrophic and dilatory remodeling may overshadow primary contractile defects. The use of a murine engineered cardiac tissue (mECT) model of cMyBP-C ablation in the present study permits delineation of the primary contractile kinetic abnormalities in an intact tissue model under mechanical loading conditions in the absence of confounding remodeling events. We generated mechanically integrated mECT using isolated postnatal day 1 mouse cardiac cells from both wild-type (WT) and cMyBP-C–null hearts. After culturing for 1 wk to establish coordinated spontaneous contraction, we measured twitch force and Ca2+ transients at 37°C during pacing at 6 and 9 Hz, with and without dobutamine. Compared with WT, the cMyBP-C–null mECT demonstrated faster late contraction kinetics and significantly faster early relaxation kinetics with no difference in Ca2+ transient kinetics. Strikingly, the ability of cMyBP-C–null mECT to increase contractile kinetics in response to adrenergic stimulation and increased pacing frequency were severely impaired. We conclude that cMyBP-C ablation results in constitutively accelerated contractile kinetics with preserved peak force with minimal contractile kinetic reserve. These functional abnormalities precede the development of the hypertrophic phenotype and do not result from alterations in Ca2+ transient kinetics, suggesting that alterations in contractile velocity may serve as the primary functional trigger for the development of hypertrophy in this model of HCM. Our findings strongly support a mechanism in which cMyBP-C functions as a physiological brake on contraction by positioning myosin heads away from the thin filament, a constraint which is removed upon adrenergic stimulation or cMyBP-C ablation.
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Affiliation(s)
- Willem J de Lange
- Department of Pediatrics, University of Wisconsin School of Medicine and Public Health, Madison, WI 53792, USA
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Bezold KL, Shaffer JF, Khosa JK, Hoye ER, Harris SP. A gain-of-function mutation in the M-domain of cardiac myosin-binding protein-C increases binding to actin. J Biol Chem 2013; 288:21496-505. [PMID: 23782699 DOI: 10.1074/jbc.m113.474346] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The M-domain is the major regulatory subunit of cardiac myosin-binding protein-C (cMyBP-C) that modulates actin and myosin interactions to influence muscle contraction. However, the precise mechanism(s) and the specific residues involved in mediating the functional effects of the M-domain are not fully understood. Positively charged residues adjacent to phosphorylation sites in the M-domain are thought to be critical for effects of cMyBP-C on cross-bridge interactions by mediating electrostatic binding with myosin S2 and/or actin. However, recent structural studies revealed that highly conserved sequences downstream of the phosphorylation sites form a compact tri-helix bundle. Here we used site-directed mutagenesis to probe the functional significance of charged residues adjacent to the phosphorylation sites and conserved residues within the tri-helix bundle. Results confirm that charged residues adjacent to phosphorylation sites and residues within the tri-helix bundle are important for mediating effects of the M-domain on contraction. In addition, four missense variants within the tri-helix bundle that are associated with human hypertrophic cardiomyopathy caused either loss-of-function or gain-of-function effects on force. Importantly, the effects of the gain-of-function variant, L348P, increased the affinity of the M-domain for actin. Together, results demonstrate that functional effects of the M-domain are not due solely to interactions with charged residues near phosphorylatable serines and provide the first demonstration that the tri-helix bundle contributes to the functional effects of the M-domain, most likely by binding to actin.
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Ackermann MA, Patel PD, Valenti J, Takagi Y, Homsher E, Sellers JR, Kontrogianni-Konstantopoulos A. Loss of actomyosin regulation in distal arthrogryposis myopathy due to mutant myosin binding protein-C slow. FASEB J 2013; 27:3217-28. [PMID: 23657818 DOI: 10.1096/fj.13-228882] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Myosin binding protein C (MyBP-C) is expressed in striated muscles, where it plays key roles in the modulation of actomyosin cross-bridges. Slow MyBP-C (sMyBP-C) consists of multiple variants sharing common domains but also containing unique segments within the NH2 and COOH termini. Two missense mutations in the NH2 terminus (W236R) and COOH terminus (Y856H) of sMyBP-C have been causally linked to the development of distal arthrogryposis-1 (DA-1), a severe skeletal muscle disorder. Using a combination of in vitro binding and motility assays, we show that the COOH terminus mediates binding of sMyBP-C to thick filaments, while the NH2 terminus modulates the formation of actomyosin cross-bridges in a variant-specific manner. Consistent with this, a recombinant NH2-terminal peptide that excludes residues 34-59 reduces the sliding velocity of actin filaments past myosin heads from 9.0 ± 1.3 to 5.7 ± 1.0 μm/s at 0.1 μM, while a recombinant peptide that excludes residues 21-59 fails to do so. Notably, the actomyosin regulatory properties of sMyBP-C are completely abolished by the presence of the DA-1 mutations. In summary, our studies are the first to show that the NH2 and COOH termini of sMyBP-C have distinct functions, which are regulated by differential splicing, and are compromized by the presence of missense point mutations linked to muscle disease.
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Affiliation(s)
- Maegen A Ackermann
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, 108 N. Greene St, Baltimore, MD 21201, USA
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