1
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Mead AF, Wood NB, Nelson SR, Palmer BM, Yang L, Previs SB, Ploysangngam A, Kennedy GG, McAdow JF, Tremble SM, Zimmermann MA, Cipolla MJ, Ebert AM, Johnson AN, Gurnett CA, Previs MJ, Warshaw DM. Functional role of myosin-binding protein H in thick filaments of developing vertebrate fast-twitch skeletal muscle. J Gen Physiol 2024; 156:e202413604. [PMID: 39373654 PMCID: PMC11461142 DOI: 10.1085/jgp.202413604] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2024] [Revised: 08/01/2024] [Accepted: 09/20/2024] [Indexed: 10/08/2024] Open
Abstract
Myosin-binding protein H (MyBP-H) is a component of the vertebrate skeletal muscle sarcomere with sequence and domain homology to myosin-binding protein C (MyBP-C). Whereas skeletal muscle isoforms of MyBP-C (fMyBP-C, sMyBP-C) modulate muscle contractility via interactions with actin thin filaments and myosin motors within the muscle sarcomere "C-zone," MyBP-H has no known function. This is in part due to MyBP-H having limited expression in adult fast-twitch muscle and no known involvement in muscle disease. Quantitative proteomics reported here reveal that MyBP-H is highly expressed in prenatal rat fast-twitch muscles and larval zebrafish, suggesting a conserved role in muscle development and prompting studies to define its function. We take advantage of the genetic control of the zebrafish model and a combination of structural, functional, and biophysical techniques to interrogate the role of MyBP-H. Transgenic, FLAG-tagged MyBP-H or fMyBP-C both localize to the C-zones in larval myofibers, whereas genetic depletion of endogenous MyBP-H or fMyBP-C leads to increased accumulation of the other, suggesting competition for C-zone binding sites. Does MyBP-H modulate contractility in the C-zone? Globular domains critical to MyBP-C's modulatory functions are absent from MyBP-H, suggesting that MyBP-H may be functionally silent. However, our results suggest an active role. In vitro motility experiments indicate MyBP-H shares MyBP-C's capacity as a molecular "brake." These results provide new insights and raise questions about the role of the C-zone during muscle development.
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Affiliation(s)
- Andrew F. Mead
- Department of Molecular Physiology and Biophysics, Larner College of Medicine, University of Vermont, Burlington, VT, USA
- Cardiovascular Research Institute, University of Vermont, Burlington, VT, USA
| | - Neil B. Wood
- Department of Molecular Physiology and Biophysics, Larner College of Medicine, University of Vermont, Burlington, VT, USA
| | - Shane R. Nelson
- Department of Molecular Physiology and Biophysics, Larner College of Medicine, University of Vermont, Burlington, VT, USA
- Cardiovascular Research Institute, University of Vermont, Burlington, VT, USA
| | - Bradley M. Palmer
- Department of Molecular Physiology and Biophysics, Larner College of Medicine, University of Vermont, Burlington, VT, USA
- Cardiovascular Research Institute, University of Vermont, Burlington, VT, USA
| | - Lin Yang
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY, USA
| | - Samantha Beck Previs
- Department of Molecular Physiology and Biophysics, Larner College of Medicine, University of Vermont, Burlington, VT, USA
- Cardiovascular Research Institute, University of Vermont, Burlington, VT, USA
| | - Angela Ploysangngam
- Department of Molecular Physiology and Biophysics, Larner College of Medicine, University of Vermont, Burlington, VT, USA
| | - Guy G. Kennedy
- Department of Molecular Physiology and Biophysics, Larner College of Medicine, University of Vermont, Burlington, VT, USA
| | - Jennifer F. McAdow
- Department of Neurlogical Sciences, Larner College of Medicine, University of Vermont, Burlington, VT, USA
| | - Sarah M. Tremble
- Department of Electrical and Biomedical Engineering, College of Engineering and Mathematical Sciences, University of Vermont, Burlington, VT, USA
| | - Marcus A. Zimmermann
- Department of Molecular Physiology and Biophysics, Larner College of Medicine, University of Vermont, Burlington, VT, USA
- Cardiovascular Research Institute, University of Vermont, Burlington, VT, USA
| | - Marilyn J. Cipolla
- Department of Electrical and Biomedical Engineering, College of Engineering and Mathematical Sciences, University of Vermont, Burlington, VT, USA
- Department of Neurology, Washington University School of Medicine in St. Louis, St. Louis, MO, USA
| | - Alicia M. Ebert
- Department of Biology, College of Arts and Sciences, University of Vermont, Burlington, VT, USA
| | - Aaron N. Johnson
- Department of Developmental Biology, Washington University School of Medicine in St. Louis, St. Louis, MO, USA
| | - Christina A. Gurnett
- Department of Developmental Biology, Washington University School of Medicine in St. Louis, St. Louis, MO, USA
| | - Michael J. Previs
- Department of Molecular Physiology and Biophysics, Larner College of Medicine, University of Vermont, Burlington, VT, USA
- Cardiovascular Research Institute, University of Vermont, Burlington, VT, USA
| | - David M. Warshaw
- Department of Molecular Physiology and Biophysics, Larner College of Medicine, University of Vermont, Burlington, VT, USA
- Cardiovascular Research Institute, University of Vermont, Burlington, VT, USA
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Mohran S, McMillen TS, Mandrycky C, Tu AY, Kooiker KB, Qian W, Neys S, Osegueda B, Moussavi-Harami F, Irving TC, Regnier M, Ma W. Calcium has a direct effect on thick filament activation in porcine myocardium. J Gen Physiol 2024; 156:e202413545. [PMID: 39302315 PMCID: PMC11415303 DOI: 10.1085/jgp.202413545] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2024] [Revised: 08/03/2024] [Accepted: 09/05/2024] [Indexed: 09/22/2024] Open
Abstract
Sarcomere activation in striated muscle requires both thin filament-based and thick filament-based activation mechanisms. Recent studies have shown that myosin heads on the thick filaments undergo OFF to ON structural transitions in response to calcium (Ca2+) in permeabilized porcine myocardium in the presence of a small molecule inhibitor that eliminated active force. The changes in X-ray diffraction signatures of OFF to ON transitions were interpreted as Ca2+ acting to activate the thick filaments. Alternatively, Ca2+ binding to troponin could initiate a Ca2+-dependent crosstalk from the thin filament to the thick filament via interfilament connections such as the myosin binding protein-C. Here, we exchanged native troponin in permeabilized porcine myocardium for troponin containing the cTnC D65A mutation, which disallows the activation of troponin through Ca2+ binding to determine if Ca2+-dependent thick filament activation persists in the absence of thin filament activation. After the exchange protocol, over 95% of the Ca2+-activated force was eliminated. Equatorial intensity ratio increased significantly in both WT and D65A exchanged myocardium with increasing Ca2+ concentration. The degree of helical ordering of the myosin heads decreased by the same amount in WT and D65A myocardium when Ca2+ concentration increased. These results are consistent with a direct effect of Ca2+ in activating the thick filament rather than an indirect effect due to Ca2+-mediated crosstalk between the thick and thin filaments.
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Affiliation(s)
- Saffie Mohran
- Department of Bioengineering, University of Washington, Seattle, WA, USA
- Center of Translational Muscle Research, University of Washington, Seattle, WA, USA
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA, USA
| | - Timothy S. McMillen
- Center of Translational Muscle Research, University of Washington, Seattle, WA, USA
| | - Christian Mandrycky
- Department of Bioengineering, University of Washington, Seattle, WA, USA
- Center of Translational Muscle Research, University of Washington, Seattle, WA, USA
| | - An-Yue Tu
- Department of Bioengineering, University of Washington, Seattle, WA, USA
- Center of Translational Muscle Research, University of Washington, Seattle, WA, USA
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA, USA
| | - Kristina B. Kooiker
- Center of Translational Muscle Research, University of Washington, Seattle, WA, USA
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA, USA
- Division of Cardiology, Department of Medicine, University of Washington, Seattle, WA, USA
- Center for Cardiovascular Biology, University of Washington, Seattle, WA, USA
| | - Wenjing Qian
- College of Basic Medical Sciences, Dalian Medical University, Dalian, China
| | - Stephanie Neys
- Division of Cardiology, Department of Medicine, University of Washington, Seattle, WA, USA
| | - Brayan Osegueda
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA, USA
| | - Farid Moussavi-Harami
- Center of Translational Muscle Research, University of Washington, Seattle, WA, USA
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA, USA
- Division of Cardiology, Department of Medicine, University of Washington, Seattle, WA, USA
- Center for Cardiovascular Biology, University of Washington, Seattle, WA, USA
| | - Thomas C. Irving
- BioCAT, Department of Biology, Illinois Institute of Technology, Chicago, IL, USA
- Center for Synchrotron Radiation Research and Instrumentation, Illinois Institute of Technology, Chicago, IL, USA
| | - Michael Regnier
- Department of Bioengineering, University of Washington, Seattle, WA, USA
- Center of Translational Muscle Research, University of Washington, Seattle, WA, USA
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA, USA
- Center for Cardiovascular Biology, University of Washington, Seattle, WA, USA
| | - Weikang Ma
- BioCAT, Department of Biology, Illinois Institute of Technology, Chicago, IL, USA
- Center for Synchrotron Radiation Research and Instrumentation, Illinois Institute of Technology, Chicago, IL, USA
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3
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Wang X, Zhu H, Terashi G, Taluja M, Kihara D. DiffModeler: large macromolecular structure modeling for cryo-EM maps using a diffusion model. Nat Methods 2024:10.1038/s41592-024-02479-0. [PMID: 39433880 DOI: 10.1038/s41592-024-02479-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2024] [Accepted: 09/19/2024] [Indexed: 10/23/2024]
Abstract
Cryogenic electron microscopy (cryo-EM) has now been widely used for determining multichain protein complexes. However, modeling a large complex structure, such as those with more than ten chains, is challenging, particularly when the map resolution decreases. Here we present DiffModeler, a fully automated method for modeling large protein complex structures. DiffModeler employs a diffusion model for backbone tracing and integrates AlphaFold2-predicted single-chain structures for structure fitting. DiffModeler showed an average template modeling score of 0.88 and 0.91 for two datasets of cryo-EM maps of 0-5 Å resolution and 0.92 for intermediate resolution maps (5-10 Å), substantially outperforming existing methodologies. Further benchmarking at low resolutions (10-20 Å) confirms its versatility, demonstrating plausible performance.
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Affiliation(s)
- Xiao Wang
- Department of Computer Science, Purdue University, West Lafayette, IN, USA
| | - Han Zhu
- Department of Computer Science, Purdue University, West Lafayette, IN, USA
| | - Genki Terashi
- Department of Biological Sciences, Purdue University, West Lafayette, IN, USA
| | - Manav Taluja
- Department of Biological Sciences, Purdue University, West Lafayette, IN, USA
- School of Computer Science and Engineering, Vellore Institute of Technology, Vellore, India
| | - Daisuke Kihara
- Department of Computer Science, Purdue University, West Lafayette, IN, USA.
- Department of Biological Sciences, Purdue University, West Lafayette, IN, USA.
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4
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Rastegarpouyani H, Hojjatian A, Taylor KA. Two Forms of Thick Filament in the Flight Muscle of Drosophila melanogaster. Int J Mol Sci 2024; 25:11313. [PMID: 39457097 DOI: 10.3390/ijms252011313] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2024] [Revised: 10/13/2024] [Accepted: 10/16/2024] [Indexed: 10/28/2024] Open
Abstract
Invertebrate striated muscle myosin filaments are highly variable in structure. The best characterized myosin filaments are those found in insect indirect flight muscle (IFM) in which the flight-powering muscles are not attached directly to the wings. Four insect orders, Hemiptera, Diptera, Hymenoptera, and Coleoptera, have evolved IFM. IFM thick filaments from the first three orders have highly similar myosin arrangements but differ significantly among their non-myosin proteins. The cryo-electron microscopy of isolated IFM myosin filaments from the Dipteran Drosophila melanogaster described here revealed the coexistence of two distinct filament types, one presenting a tubular backbone like in previous work and the other a solid backbone. Inside an annulus of myosin tails, tubular filaments show no noticeable densities; solid filaments show four paired paramyosin densities. Both myosin heads of the tubular filaments are disordered; solid filaments have one completely and one partially immobilized head. Tubular filaments have the protein stretchin-klp on their surface; solid filaments do not. Two proteins, flightin and myofilin, are identifiable in all the IFM filaments previously determined. In Drosophila, flightin assumes two conformations, being compact in solid filaments and extended in tubular filaments. Nearly identical solid filaments occur in the large water bug Lethocerus indicus, which flies infrequently. The Drosophila tubular filaments occur in younger flies, and the solid filaments appear in older flies, which fly less frequently if at all, suggesting that the solid filament form is correlated with infrequent muscle use. We suggest that the solid form is designed to conserve ATP when the muscle is not in active use.
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Affiliation(s)
- Hosna Rastegarpouyani
- Institute of Molecular Biophysics, Florida State University, Tallahassee, FL 32306-4380, USA
- Department of Biological Science, Florida State University, Tallahassee, FL 32306-4295, USA
| | - Alimohammad Hojjatian
- Institute of Molecular Biophysics, Florida State University, Tallahassee, FL 32306-4380, USA
| | - Kenneth A Taylor
- Institute of Molecular Biophysics, Florida State University, Tallahassee, FL 32306-4380, USA
- Department of Biological Science, Florida State University, Tallahassee, FL 32306-4295, USA
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5
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Kochurova AM, Beldiia EA, Nefedova VV, Yampolskaya DS, Koubassova NA, Kleymenov SY, Antonets JY, Ryabkova NS, Katrukha IA, Bershitsky SY, Matyushenko AM, Kopylova GV, Shchepkin DV. The D75N and P161S Mutations in the C0-C2 Fragment of cMyBP-C Associated with Hypertrophic Cardiomyopathy Disturb the Thin Filament Activation, Nucleotide Exchange in Myosin, and Actin-Myosin Interaction. Int J Mol Sci 2024; 25:11195. [PMID: 39456977 DOI: 10.3390/ijms252011195] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2024] [Revised: 09/17/2024] [Accepted: 09/20/2024] [Indexed: 10/28/2024] Open
Abstract
About half of the mutations that lead to hypertrophic cardiomyopathy (HCM) occur in the MYBPC3 gene. However, the molecular mechanisms of pathogenicity of point mutations in cardiac myosin-binding protein C (cMyBP-C) remain poorly understood. In this study, we examined the effects of the D75N and P161S substitutions in the C0 and C1 domains of cMyBP-C on the structural and functional properties of the C0-C1-m-C2 fragment (C0-C2). Differential scanning calorimetry revealed that these mutations disorder the tertiary structure of the C0-C2 molecule. Functionally, the D75N mutation reduced the maximum sliding velocity of regulated thin filaments in an in vitro motility assay, while the P161S mutation increased it. Both mutations significantly reduced the calcium sensitivity of the actin-myosin interaction and impaired thin filament activation by cross-bridges. D75N and P161S C0-C2 fragments substantially decreased the sliding velocity of the F-actin-tropomyosin filament. ADP dose-dependently reduced filament sliding velocity in the presence of WT and P161S fragments, but the velocity remained unchanged with the D75N fragment. We suppose that the D75N mutation alters nucleotide exchange kinetics by decreasing ADP affinity to the ATPase pocket and slowing the myosin cycle. Our molecular dynamics simulations mean that the D75N mutation affects myosin S1 function. Both mutations impair cardiac contractility by disrupting thin filament activation. The results offer new insights into the HCM pathogenesis caused by missense mutations in N-terminal domains of cMyBP-C, highlighting the distinct effects of D75N and P161S mutations on cardiac contractile function.
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Affiliation(s)
- Anastasia M Kochurova
- Institute of Immunology and Physiology of the Russian Academy of Sciences, 620049 Yekaterinburg, Russia
| | - Evgenia A Beldiia
- Institute of Immunology and Physiology of the Russian Academy of Sciences, 620049 Yekaterinburg, Russia
| | - Victoria V Nefedova
- Research Center of Biotechnology of the Russian Academy of Sciences, 119071 Moscow, Russia
| | - Daria S Yampolskaya
- Research Center of Biotechnology of the Russian Academy of Sciences, 119071 Moscow, Russia
| | | | - Sergey Y Kleymenov
- Research Center of Biotechnology of the Russian Academy of Sciences, 119071 Moscow, Russia
- Koltzov Institute of Developmental Biology, Russian Academy of Sciences, 119334 Moscow, Russia
| | - Julia Y Antonets
- Institute of Immunology and Physiology of the Russian Academy of Sciences, 620049 Yekaterinburg, Russia
| | - Natalia S Ryabkova
- Department of Biochemistry, Faculty of Biology, Lomonosov Moscow State University, 119991 Moscow, Russia
- HyTest Ltd., 20520 Turku, Finland
| | - Ivan A Katrukha
- Department of Biochemistry, Faculty of Biology, Lomonosov Moscow State University, 119991 Moscow, Russia
- HyTest Ltd., 20520 Turku, Finland
| | - Sergey Y Bershitsky
- Institute of Immunology and Physiology of the Russian Academy of Sciences, 620049 Yekaterinburg, Russia
| | | | - Galina V Kopylova
- Institute of Immunology and Physiology of the Russian Academy of Sciences, 620049 Yekaterinburg, Russia
| | - Daniil V Shchepkin
- Institute of Immunology and Physiology of the Russian Academy of Sciences, 620049 Yekaterinburg, Russia
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6
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Szczesna-Cordary D. Novel cardiac myosin inhibitor for hypertrophic cardiomyopathy. J Gen Physiol 2024; 156:e202413640. [PMID: 39136654 PMCID: PMC11318667 DOI: 10.1085/jgp.202413640] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/13/2024] Open
Abstract
New RLC-1 small-molecule inhibits actomyosin interactions, reduces contractile force, and speeds up myosin cross-bridge kinetics.
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Affiliation(s)
- Danuta Szczesna-Cordary
- Department of Molecular and Cellular Pharmacology, University of Miami, Miller School of Medicine, Miami, FL, USA
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7
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Mertens J, De Lange WJ, Farrell ET, Harbaugh EC, Gauchan A, Fitzsimons DP, Moss RL, Ralphe JC. The W792R HCM missense mutation in the C6 domain of cardiac myosin binding protein-C increases contractility in neonatal mouse myocardium. J Mol Cell Cardiol 2024; 195:14-23. [PMID: 39059462 DOI: 10.1016/j.yjmcc.2024.07.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/02/2024] [Revised: 07/22/2024] [Accepted: 07/23/2024] [Indexed: 07/28/2024]
Abstract
Missense mutations in cardiac myosin binding protein C (cMyBP-C) are known to cause hypertrophic cardiomyopathy (HCM). The W792R mutation in the C6 domain of cMyBP-C causes severe, early onset HCM in humans, yet its impact on the function of cMyBP-C and the mechanism through which it causes disease remain unknown. To fully characterize the effect of the W792R mutation on cardiac morphology and function in vivo, we generated a murine knock-in model. We crossed heterozygous W792RWR mice to produce homozygous mutant W792RRR, heterozygous W792RWR, and control W792RWW mice. W792RRR mice present with cardiac hypertrophy, myofibrillar disarray and fibrosis by postnatal day 10 (PND10), and do not survive past PND21. Full-length cMyBP-C is present at similar levels in W792RWW, W792RWR and W792RRR mice and is properly incorporated into the sarcomere. Heterozygous W792RWR mice displayed normal heart morphology and contractility. Permeabilized myocardium from PND10 W792RRR mice showed increased Ca2+ sensitivity, accelerated cross-bridge cycling kinetics, decreased cooperativity in the activation of force, and increased expression of hypertrophy-related genes. In silico modeling suggests that the W792R mutation destabilizes the fold of the C6 domain and increases torsion in the C5-C7 region, possibly impacting regulatory interactions of cMyBP-C with myosin and actin. Based on the data presented here, we propose a model in which mutant W792R cMyBP-C preferentially forms Ca2+ sensitizing interactions with actin, rather than inhibitory interactions with myosin. The W792R-cMyBP-C mouse model provides mechanistic insights into the pathology of this mutation and may provide a mechanism by which other central domain missense mutations in cMyBP-C may alter contractility, leading to HCM.
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Affiliation(s)
- Jasmine Mertens
- Department of Pediatrics, University of Wisconsin School of Medicine and Public Health, Madison, WI 53706, United States of America; UW Cardiovascular Research Center, University of Wisconsin School of Medicine and Public Health, Madison, WI 53706, United States of America
| | - Willem J De Lange
- Department of Pediatrics, University of Wisconsin School of Medicine and Public Health, Madison, WI 53706, United States of America; UW Cardiovascular Research Center, University of Wisconsin School of Medicine and Public Health, Madison, WI 53706, United States of America
| | - Emily T Farrell
- Department of Pediatrics, University of Wisconsin School of Medicine and Public Health, Madison, WI 53706, United States of America; UW Cardiovascular Research Center, University of Wisconsin School of Medicine and Public Health, Madison, WI 53706, United States of America
| | - Ella C Harbaugh
- Department of Pediatrics, University of Wisconsin School of Medicine and Public Health, Madison, WI 53706, United States of America; UW Cardiovascular Research Center, University of Wisconsin School of Medicine and Public Health, Madison, WI 53706, United States of America
| | - Angeela Gauchan
- Department of Pediatrics, University of Wisconsin School of Medicine and Public Health, Madison, WI 53706, United States of America; UW Cardiovascular Research Center, University of Wisconsin School of Medicine and Public Health, Madison, WI 53706, United States of America
| | - Daniel P Fitzsimons
- UW Cardiovascular Research Center, University of Wisconsin School of Medicine and Public Health, Madison, WI 53706, United States of America; Department of Cell and Regenerative Biology, University of Wisconsin School of Medicine and Public Health, Madison, WI 53706, United States of America
| | - Richard L Moss
- UW Cardiovascular Research Center, University of Wisconsin School of Medicine and Public Health, Madison, WI 53706, United States of America; Department of Cell and Regenerative Biology, University of Wisconsin School of Medicine and Public Health, Madison, WI 53706, United States of America
| | - J Carter Ralphe
- Department of Pediatrics, University of Wisconsin School of Medicine and Public Health, Madison, WI 53706, United States of America; UW Cardiovascular Research Center, University of Wisconsin School of Medicine and Public Health, Madison, WI 53706, United States of America.
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8
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Turner KL, Vander Top BJ, Kooiker KB, Mohran S, Mandrycky C, McMillen T, Regnier M, Irving TC, Ma W, Tanner BC. The structural and functional effects of myosin regulatory light chain phosphorylation are amplified by increases in sarcomere length and [Ca 2+]. J Physiol 2024; 602:4941-4958. [PMID: 39283968 PMCID: PMC11466700 DOI: 10.1113/jp286802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2024] [Accepted: 08/21/2024] [Indexed: 10/04/2024] Open
Abstract
Precise regulation of sarcomeric contraction is essential for normal cardiac function. The heart must generate sufficient force to pump blood throughout the body, but either inadequate or excessive force can lead to dysregulation and disease. Myosin regulatory light chain (RLC) is a thick-filament protein that binds to the neck of the myosin heavy chain. Post-translational phosphorylation of RLC (RLC-P) by myosin light chain kinase is known to influence acto-myosin interactions, thereby increasing force production and Ca2+-sensitivity of contraction. Here, we investigated the role of RLC-P on cardiac structure and function as sarcomere length and [Ca2+] were altered. We found that at low, non-activating levels of Ca2+, RLC-P contributed to myosin head disorder, though there were no effects on isometric stress production and viscoelastic stiffness. With increases in sarcomere length and Ca2+-activation, the structural changes due to RLC-P become greater, which translates into greater force production, greater viscoelastic stiffness, slowed myosin detachment rates and altered nucleotide handling. Altogether, these data suggest that RLC-P may alter thick-filament structure by releasing ordered, off-state myosin. These more disordered myosin heads are available to bind actin, which could result in greater force production as Ca2+ levels increase. However, prolonged cross-bridge attachment duration due to slower ADP release could delay relaxation long enough to enable cross-bridge rebinding. Together, this work further elucidates the effects of RLC-P in regulating muscle function, thereby promoting a better understanding of thick-filament regulatory contributions to cardiac function in health and disease. KEY POINTS: Myosin regulatory light chain (RLC) is a thick-filament protein in the cardiac sarcomere that can be phosphorylated (RLC-P), and changes in RLC-P are associated with cardiac dysfunction and disease. This study assesses how RLC-P alters cardiac muscle structure and function at different sarcomere lengths and calcium concentrations. At low, non-activating levels of Ca2+, RLC-P contributed to myofilament disorder, though there were no effects on isometric stress production and viscoelastic stiffness. With increases in sarcomere length and Ca2+-activation, the structural changes due to RLC-P become greater, which translates into greater force production, greater viscoelastic stiffness, slower myosin detachment rate and altered cross-bridge nucleotide handling rates. This work elucidates the role of RLC-P in regulating muscle function and facilitates understanding of thick-filament regulatory protein contributions to cardiac function in health and disease.
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Affiliation(s)
- Kyrah L. Turner
- School of Molecular Biosciences, Washington State University, Pullman, Washington
| | - Blake J. Vander Top
- Department of Integrative Physiology and Neuroscience, Washington State University, Pullman, Washington
| | - Kristina B. Kooiker
- Division of Cardiology, Department of Medicine, University of Washington, Seattle, Washington
- Center for Translational Muscle Research, University of Washington, Seattle, Washington
- Center for Cardiovascular Biology, University of Washington, Seattle, Washington
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, Washington
| | - Saffie Mohran
- Division of Cardiology, Department of Medicine, University of Washington, Seattle, Washington
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, Washington
- Department of Bioengineering, University of Washington, Seattle, Washington
| | - Christian Mandrycky
- Division of Cardiology, Department of Medicine, University of Washington, Seattle, Washington
- Department of Bioengineering, University of Washington, Seattle, Washington
| | - Tim McMillen
- Division of Cardiology, Department of Medicine, University of Washington, Seattle, Washington
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, Washington
- Department of Bioengineering, University of Washington, Seattle, Washington
| | - Michael Regnier
- Division of Cardiology, Department of Medicine, University of Washington, Seattle, Washington
- Center for Translational Muscle Research, University of Washington, Seattle, Washington
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, Washington
- Department of Bioengineering, University of Washington, Seattle, Washington
| | - Thomas C. Irving
- Department of Biology, Illinois Institute of Technology, Chicago, Illinois
- Center for Synchrotron Radiation Research and Instrumentation, Illinois Institute of Technology, Chicago, Illinois
| | - Weikang Ma
- Department of Biology, Illinois Institute of Technology, Chicago, Illinois
- Center for Synchrotron Radiation Research and Instrumentation, Illinois Institute of Technology, Chicago, Illinois
| | - Bertrand C.W. Tanner
- Department of Integrative Physiology and Neuroscience, Washington State University, Pullman, Washington
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9
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Spudich JA, Nandwani N, Robert-Paganin J, Houdusse A, Ruppel KM. Reassessing the unifying hypothesis for hypercontractility caused by myosin mutations in hypertrophic cardiomyopathy. EMBO J 2024; 43:4139-4155. [PMID: 39192034 PMCID: PMC11445530 DOI: 10.1038/s44318-024-00199-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2024] [Revised: 07/12/2024] [Accepted: 07/18/2024] [Indexed: 08/29/2024] Open
Affiliation(s)
- James A Spudich
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA, 94305, USA.
| | - Neha Nandwani
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA, 94305, USA
| | - Julien Robert-Paganin
- Structural Motility, Institut Curie, Paris Université Sciences et Lettres, Sorbonne Université, CNRS UMR144, F-75005, Paris, France
| | - Anne Houdusse
- Structural Motility, Institut Curie, Paris Université Sciences et Lettres, Sorbonne Université, CNRS UMR144, F-75005, Paris, France
| | - Kathleen M Ruppel
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA, 94305, USA.
- Department of Pediatrics, Stanford University School of Medicine, Stanford, CA, 94305, USA.
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10
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Sitbon YH, Kazmierczak K, Liang J, Kloehn AJ, Vinod J, Kanashiro-Takeuchi R, Szczesna-Cordary D. Dual effect of N-terminal deletion of cardiac myosin essential light chain in mitigating cardiomyopathy. iScience 2024; 27:110591. [PMID: 39211545 PMCID: PMC11357882 DOI: 10.1016/j.isci.2024.110591] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2024] [Revised: 06/14/2024] [Accepted: 07/23/2024] [Indexed: 09/04/2024] Open
Abstract
We investigated the role of the N-terminus (residues 1-43) of the myosin essential light chain (N-ELC) in regulating cardiac function in hypertrophic (HCM-A57G) and restrictive (RCM-E143K) cardiomyopathy mice. Both models were cross-genotyped with N-ELC-truncated Δ43 mice, and the offspring were studied using echocardiography and muscle contractile mechanics. In A57G×Δ43 mice, Δ43 expression improved heart function and reduced hypertrophy and fibrosis. No improvements were seen in E143K×Δ43 compared to RCM-E143K mice. HCM-mutant pathology involved an impaired N-ELC tension sensor, disrupted N-ELC-actin interactions, an altered force-pCa relationship, and a destabilized myosin's super-relaxed state. Removal of the malfunctioning N-ELC sensor led to functional rescue in HCM-truncated mutant hearts. However, the RCM mutation could not be rescued by N-ELC deletion, likely due to its proximity to the myosin motor domain, affecting lever-arm rigidity and myosin function. This study provides insights into the role of N-ELC in the development and potential rescue of ELC-mutant cardiomyopathy.
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Affiliation(s)
- Yoel H. Sitbon
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Katarzyna Kazmierczak
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Jingsheng Liang
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Andrew J. Kloehn
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Judith Vinod
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Rosemeire Kanashiro-Takeuchi
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Danuta Szczesna-Cordary
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL 33136, USA
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11
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Kyrilis FL, Low JKK, Mackay JP, Kastritis PL. Structural biology in cellulo: Minding the gap between conceptualization and realization. Curr Opin Struct Biol 2024; 87:102843. [PMID: 38788606 DOI: 10.1016/j.sbi.2024.102843] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2024] [Revised: 04/30/2024] [Accepted: 05/01/2024] [Indexed: 05/26/2024]
Abstract
Recent technological advances have deepened our perception of cellular structure. However, most structural data doesn't originate from intact cells, limiting our understanding of cellular processes. Here, we discuss current and future developments that will bring us towards a structural picture of the cell. Electron cryotomography is the standard bearer, with its ability to provide in cellulo snapshots. Single-particle electron microscopy (of purified biomolecules and of complex mixtures) and covalent crosslinking combined with mass spectrometry also have significant roles to play, as do artificial intelligence algorithms in their many guises. To integrate these multiple approaches, data curation and standardisation will be critical - as is the need to expand efforts beyond our current protein-centric view to the other (macro)molecules that sustain life.
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Affiliation(s)
- Fotis L Kyrilis
- Institute of Chemical Biology, National Hellenic Research Foundation, Athens, Greece. https://twitter.com/Fotansky_16
| | - Jason K K Low
- School of Life and Environmental Sciences, University of Sydney, Sydney, NSW 2006, Australia
| | - Joel P Mackay
- School of Life and Environmental Sciences, University of Sydney, Sydney, NSW 2006, Australia.
| | - Panagiotis L Kastritis
- Institute of Chemical Biology, National Hellenic Research Foundation, Athens, Greece; Interdisciplinary Research Center HALOmem, Charles Tanford Protein Center, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Straße 3a, Halle/Saale, Germany; Institute of Biochemistry and Biotechnology, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Straße 3, Halle/Saale, Germany; Biozentrum, Martin Luther University Halle-Wittenberg, Weinbergweg 22, Halle/Saale, Germany.
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12
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Hartman JJ, Hwee DT, Robert-Paganin J, Chuang C, Chin ER, Edell S, Lee KH, Madhvani R, Paliwal P, Pernier J, Sarkar SS, Schaletzky J, Schauer K, Taheri KD, Wang J, Wehri E, Wu Y, Houdusse A, Morgan BP, Malik FI. Aficamten is a small-molecule cardiac myosin inhibitor designed to treat hypertrophic cardiomyopathy. NATURE CARDIOVASCULAR RESEARCH 2024; 3:1003-1016. [PMID: 39196032 PMCID: PMC11358156 DOI: 10.1038/s44161-024-00505-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Accepted: 06/06/2024] [Indexed: 08/29/2024]
Abstract
Hypertrophic cardiomyopathy (HCM) is an inherited disease of the sarcomere resulting in excessive cardiac contractility. The first-in-class cardiac myosin inhibitor, mavacamten, improves symptoms in obstructive HCM. Here we present aficamten, a selective small-molecule inhibitor of cardiac myosin that diminishes ATPase activity by strongly slowing phosphate release, stabilizing a weak actin-binding state. Binding to an allosteric site on the myosin catalytic domain distinct from mavacamten, aficamten prevents the conformational changes necessary to enter the strongly actin-bound force-generating state. In doing so, aficamten reduces the number of functional myosin heads driving sarcomere shortening. The crystal structure of aficamten bound to cardiac myosin in the pre-powerstroke state provides a basis for understanding its selectivity over smooth and fast skeletal muscle. Furthermore, in cardiac myocytes and in mice bearing the hypertrophic R403Q cardiac myosin mutation, aficamten reduces cardiac contractility. Our findings suggest aficamten holds promise as a therapy for HCM.
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Affiliation(s)
- James J Hartman
- Research and Non-Clinical Development, Cytokinetics, South San Francisco, CA, USA.
| | - Darren T Hwee
- Research and Non-Clinical Development, Cytokinetics, South San Francisco, CA, USA
| | - Julien Robert-Paganin
- Structural Motility, Institut Curie, Université Paris Sciences et Lettres, Sorbonne Université, CNRS UMR144, Paris, France
| | - Chihyuan Chuang
- Research and Non-Clinical Development, Cytokinetics, South San Francisco, CA, USA
| | - Eva R Chin
- Research and Non-Clinical Development, Cytokinetics, South San Francisco, CA, USA
| | - Samantha Edell
- Research and Non-Clinical Development, Cytokinetics, South San Francisco, CA, USA
| | - Ken H Lee
- Research and Non-Clinical Development, Cytokinetics, South San Francisco, CA, USA
| | - Roshni Madhvani
- Research and Non-Clinical Development, Cytokinetics, South San Francisco, CA, USA
| | - Preeti Paliwal
- Research and Non-Clinical Development, Cytokinetics, South San Francisco, CA, USA
| | - Julien Pernier
- Tumor Cell Dynamics Unit, Inserm U1279 Gustave Roussy Institute, Université Paris-Saclay, Villejuif, France
| | | | - Julia Schaletzky
- Research and Non-Clinical Development, Cytokinetics, South San Francisco, CA, USA
| | - Kristine Schauer
- Tumor Cell Dynamics Unit, Inserm U1279 Gustave Roussy Institute, Université Paris-Saclay, Villejuif, France
| | - Khanha D Taheri
- Research and Non-Clinical Development, Cytokinetics, South San Francisco, CA, USA
| | - Jingying Wang
- Research and Non-Clinical Development, Cytokinetics, South San Francisco, CA, USA
| | - Eddie Wehri
- Research and Non-Clinical Development, Cytokinetics, South San Francisco, CA, USA
| | - Yangsong Wu
- Research and Non-Clinical Development, Cytokinetics, South San Francisco, CA, USA
| | - Anne Houdusse
- Structural Motility, Institut Curie, Université Paris Sciences et Lettres, Sorbonne Université, CNRS UMR144, Paris, France
| | - Bradley P Morgan
- Research and Non-Clinical Development, Cytokinetics, South San Francisco, CA, USA
| | - Fady I Malik
- Research and Non-Clinical Development, Cytokinetics, South San Francisco, CA, USA
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13
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Irving M. Functional control of myosin motors in the cardiac cycle. Nat Rev Cardiol 2024:10.1038/s41569-024-01063-5. [PMID: 39030271 DOI: 10.1038/s41569-024-01063-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 07/02/2024] [Indexed: 07/21/2024]
Abstract
Contraction of the heart is driven by cyclical interactions between myosin and actin filaments powered by ATP hydrolysis. The modular structure of heart muscle and the organ-level synchrony of the heartbeat ensure tight reciprocal coupling between this myosin ATPase cycle and the macroscopic cardiac cycle. The myosin motors respond to the cyclical activation of the actin and myosin filaments to drive the pressure changes that control the inflow and outflow valves of the heart chambers. Opening and closing of the valves in turn switches the myosin motors between roughly isometric and roughly isotonic contraction modes. Peak filament stress in the heart is much smaller than in fully activated skeletal muscle, although the myosin filaments in the two muscle types have the same number of myosin motors. Calculations indicate that only ~5% of the myosin motors in the heart are needed to generate peak systolic pressure, although many more motors are needed to drive ejection. Tight regulation of the number of active motors is essential for the efficient functioning of the healthy heart - this control is commonly disrupted by gene variants associated with inherited heart disease, and its restoration might be a useful end point in the development of novel therapies.
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Affiliation(s)
- Malcolm Irving
- Randall Centre for Cell and Molecular Biophysics and BHF Centre for Research Excellence, King's College London, London, UK.
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14
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Childers MC, Geeves MA, Regnier M. An atomistic model of myosin interacting heads motif dynamics and their modification by 2'-deoxy-ADP. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.06.597809. [PMID: 38895221 PMCID: PMC11185614 DOI: 10.1101/2024.06.06.597809] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/21/2024]
Abstract
The contraction of striated muscle is driven by cycling myosin motor proteins embedded within the thick filaments of sarcomeres. In addition to cross-bridge cycling with actin, these myosin proteins can enter an inactive, sequestered state in which the globular S1 heads rest along the thick filament surface and are unable to perform motor activities. Structurally, this state is called the interacting heads motif (IHM) and is a critical conformational state of myosin that regulates muscle contractility and energy expenditure. Structural perturbation of the sequestered state via missense mutations can pathologically disrupt the mechanical performance of muscle tissue. Thus, the IHM state has become a target for therapeutic intervention. An ATP analogue called 2'-deoxy-ATP (dATP) is a potent myosin activator which destabilizes the IHM. Here we use molecular dynamics simulations to study the molecular mechanisms by which dATP modifies the structure and dynamics of myosin in a sequestered state. Simulations with IHM containing ADP.Pi in both nucleotide binding pockets revealed residual dynamics in an otherwise 'inactive' and 'sequestered' state of a motor protein. Replacement of ADP.Pi by dADP.Pi triggered a series of structural changes that modify the protein-protein interface that stabilizes the sequestered state, and changes to this interface were accompanied by allosteric changes in remote regions of the protein complex. A comparative analysis of these dynamics predicted new structural sites that may affect IHM stability.
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15
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Auguin D, Robert-Paganin J, Réty S, Kikuti C, David A, Theumer G, Schmidt AW, Knölker HJ, Houdusse A. Omecamtiv mecarbil and Mavacamten target the same myosin pocket despite opposite effects in heart contraction. Nat Commun 2024; 15:4885. [PMID: 38849353 PMCID: PMC11161628 DOI: 10.1038/s41467-024-47587-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Accepted: 04/03/2024] [Indexed: 06/09/2024] Open
Abstract
Inherited cardiomyopathies are common cardiac diseases worldwide, leading in the late stage to heart failure and death. The most promising treatments against these diseases are small molecules directly modulating the force produced by β-cardiac myosin, the molecular motor driving heart contraction. Omecamtiv mecarbil and Mavacamten are two such molecules that completed phase 3 clinical trials, and the inhibitor Mavacamten is now approved by the FDA. In contrast to Mavacamten, Omecamtiv mecarbil acts as an activator of cardiac contractility. Here, we reveal by X-ray crystallography that both drugs target the same pocket and stabilize a pre-stroke structural state, with only few local differences. All-atom molecular dynamics simulations reveal how these molecules produce distinct effects in motor allostery thus impacting force production in opposite way. Altogether, our results provide the framework for rational drug development for the purpose of personalized medicine.
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Affiliation(s)
- Daniel Auguin
- Structural Motility, Institut Curie, Université Paris Sciences et Lettres, Sorbonne Université, CNRS UMR144, Paris, 75248, France
- Laboratoire de Physiologie, Ecologie et Environnement (P2E), UPRES EA 1207/USC INRAE-1328, UFR Sciences et Techniques, Université d'Orléans, Orléans, France
| | - Julien Robert-Paganin
- Structural Motility, Institut Curie, Université Paris Sciences et Lettres, Sorbonne Université, CNRS UMR144, Paris, 75248, France
| | - Stéphane Réty
- Laboratoire de Biologie et Modélisation de la Cellule, ENS de Lyon, CNRS, UMR 5239, Inserm, U1293, Université Claude Bernard Lyon 1, Lyon, France
| | - Carlos Kikuti
- Structural Motility, Institut Curie, Université Paris Sciences et Lettres, Sorbonne Université, CNRS UMR144, Paris, 75248, France
| | - Amandine David
- Structural Motility, Institut Curie, Université Paris Sciences et Lettres, Sorbonne Université, CNRS UMR144, Paris, 75248, France
| | | | | | | | - Anne Houdusse
- Structural Motility, Institut Curie, Université Paris Sciences et Lettres, Sorbonne Université, CNRS UMR144, Paris, 75248, France.
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16
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Duno-Miranda S, Nelson SR, Rasicci DV, Bodt SM, Cirilo JA, Vang D, Sivaramakrishnan S, Yengo CM, Warshaw DM. Tail length and E525K dilated cardiomyopathy mutant alter human β-cardiac myosin super-relaxed state. J Gen Physiol 2024; 156:e202313522. [PMID: 38709176 PMCID: PMC11074782 DOI: 10.1085/jgp.202313522] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Revised: 03/18/2024] [Accepted: 04/17/2024] [Indexed: 05/07/2024] Open
Abstract
Dilated cardiomyopathy (DCM) is a condition characterized by impaired cardiac function, due to myocardial hypo-contractility, and is associated with point mutations in β-cardiac myosin, the molecular motor that powers cardiac contraction. Myocardial function can be modulated through sequestration of myosin motors into an auto-inhibited "super-relaxed" state (SRX), which may be further stabilized by a structural state known as the "interacting heads motif" (IHM). Here, we sought to determine whether hypo-contractility of DCM myocardium results from reduced function of individual myosin molecules or from decreased myosin availability to interact with actin due to increased IHM/SRX stabilization. We used an established DCM myosin mutation, E525K, and characterized the biochemical and mechanical activity of wild-type and mutant human β-cardiac myosin constructs that differed in the length of their coiled-coil tail, which dictates their ability to form the IHM/SRX state. We found that short-tailed myosin constructs exhibited low IHM/SRX content, elevated actin-activated ATPase activity, and fast velocities in unloaded motility assays. Conversely, longer-tailed constructs exhibited higher IHM/SRX content and reduced actomyosin ATPase and velocity. Our modeling suggests that reduced velocities may be attributed to IHM/SRX-dependent sequestration of myosin heads. Interestingly, longer-tailed E525K mutants showed no apparent impact on velocity or actomyosin ATPase at low ionic strength but stabilized IHM/SRX state at higher ionic strength. Therefore, the hypo-contractility observed in DCM may be attributable to reduced myosin head availability caused by enhanced IHM/SRX stability in E525K mutants.
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Affiliation(s)
- Sebastian Duno-Miranda
- Department of Molecular Physiology and Biophysics, Cardiovascular Research Institute, University of Vermont, Burlington, VT, USA
| | - Shane R. Nelson
- Department of Molecular Physiology and Biophysics, Cardiovascular Research Institute, University of Vermont, Burlington, VT, USA
| | - David V. Rasicci
- Department of Cellular and Molecular Physiology, Penn State College of Medicine, Hershey, PA, USA
| | - Skylar M.L. Bodt
- Department of Cellular and Molecular Physiology, Penn State College of Medicine, Hershey, PA, USA
| | - Joseph A. Cirilo
- Department of Cellular and Molecular Physiology, Penn State College of Medicine, Hershey, PA, USA
| | - Duha Vang
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, MN, USA
| | - Sivaraj Sivaramakrishnan
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, MN, USA
| | - Christopher M. Yengo
- Department of Cellular and Molecular Physiology, Penn State College of Medicine, Hershey, PA, USA
| | - David M. Warshaw
- Department of Molecular Physiology and Biophysics, Cardiovascular Research Institute, University of Vermont, Burlington, VT, USA
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17
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Schneider J, Jasnin M. Molecular architecture of the actin cytoskeleton: From single cells to whole organisms using cryo-electron tomography. Curr Opin Cell Biol 2024; 88:102356. [PMID: 38608425 DOI: 10.1016/j.ceb.2024.102356] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2024] [Revised: 03/18/2024] [Accepted: 03/19/2024] [Indexed: 04/14/2024]
Abstract
Cryo-electron tomography (cryo-ET) has begun to provide intricate views of cellular architecture at unprecedented resolutions. Considerable efforts are being made to further optimize and automate the cryo-ET workflow, from sample preparation to data acquisition and analysis, to enable visual proteomics inside of cells. Here, we will discuss the latest advances in cryo-ET that go hand in hand with their application to the actin cytoskeleton. The development of deep learning tools for automated annotation of tomographic reconstructions and the serial lift-out sample preparation procedure will soon make it possible to perform high-resolution structural biology in a whole new range of samples, from multicellular organisms to organoids and tissues.
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Affiliation(s)
- Jonathan Schneider
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany; Helmholtz Pioneer Campus, Helmholtz Munich, 85764 Neuherberg, Germany
| | - Marion Jasnin
- Helmholtz Pioneer Campus, Helmholtz Munich, 85764 Neuherberg, Germany; Department of Chemistry, Technical University of Munich, 85748 Garching, Germany.
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18
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Zhao J, Qi L, Yuan S, Irving TC, Ma W. Differences in thick filament activation in fast rodent skeletal muscle and slow porcine cardiac muscle. J Physiol 2024; 602:2751-2762. [PMID: 38695322 PMCID: PMC11178443 DOI: 10.1113/jp286072] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Accepted: 04/16/2024] [Indexed: 06/15/2024] Open
Abstract
There is a growing appreciation that regulation of muscle contraction requires both thin filament and thick filament activation in order to fully activate the sarcomere. The prevailing mechano-sensing model for thick filament activation was derived from experiments on fast-twitch muscle. We address the question whether, or to what extent, this mechanism can be extrapolated to the slow muscle in the hearts of large mammals, including humans. We investigated the similarities and differences in structural signatures of thick filament activation in porcine myocardium as compared to fast rat extensor digitorum longus (EDL) skeletal muscle under relaxed conditions and sub-maximal contraction using small angle X-ray diffraction. Thick and thin filaments were found to adopt different structural configurations under relaxing conditions, and myosin heads showed different changes in configuration upon sub-maximal activation, when comparing the two muscle types. Titin was found to have an X-ray diffraction signature distinct from those of the overall thick filament backbone, and its spacing change appeared to be positively correlated to the force exerted on the thick filament. Structural changes in fast EDL muscle were found to be consistent with the mechano-sensing model. In porcine myocardium, however, the structural basis of mechano-sensing is blunted suggesting the need for additional activation mechanism(s) in slow cardiac muscle. These differences in thick filament regulation can be related to their different physiological roles where fast muscle is optimized for rapid, burst-like, contractions, and the slow cardiac muscle in large mammalian hearts adopts a more finely tuned, graded response to allow for their substantial functional reserve. KEY POINTS: Both thin filament and thick filament activation are required to fully activate the sarcomere. Thick and thin filaments adopt different structural configurations under relaxing conditions, and myosin heads show different changes in configuration upon sub-maximal activation in fast extensor digitorum longus muscle and slow porcine cardiac muscle. Titin has an X-ray diffraction signature distinct from those of the overall thick filament backbone and this titin reflection spacing change appeared to be directly proportional to the force exerted on the thick filament. Mechano-sensing is blunted in porcine myocardium suggesting the need for additional activation mechanism(s) in slow cardiac muscle. Fast skeletal muscle is optimized for rapid, burst-like contractions, and the slow cardiac muscle in large mammalian hearts adopts a more finely tuned graded response to allow for their substantial functional reserve.
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Affiliation(s)
- Jing Zhao
- College of Basic Medical Sciences, Dalian Medical University, Dalian, Liaoning, China
| | - Lin Qi
- Department of Biology, Illinois Institute of Technology, Chicago, IL, USA
| | - Shengyao Yuan
- BioCAT, Department of Biology, Illinois Institute of Technology, Chicago, IL, USA
| | - Thomas C Irving
- BioCAT, Department of Biology, Illinois Institute of Technology, Chicago, IL, USA
- Center for Synchrotron Radiation Research and Instrumentation, Illinois Institute of Technology, Chicago, IL, USA
| | - Weikang Ma
- BioCAT, Department of Biology, Illinois Institute of Technology, Chicago, IL, USA
- Center for Synchrotron Radiation Research and Instrumentation, Illinois Institute of Technology, Chicago, IL, USA
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19
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Hessel AL, Kuehn MN, Han SW, Ma W, Irving TC, Momb BA, Song T, Sadayappan S, Linke WA, Palmer BM. Fast myosin binding protein C knockout in skeletal muscle alters length-dependent activation and myofilament structure. Commun Biol 2024; 7:648. [PMID: 38802450 PMCID: PMC11130249 DOI: 10.1038/s42003-024-06265-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2023] [Accepted: 04/29/2024] [Indexed: 05/29/2024] Open
Abstract
In striated muscle, the sarcomeric protein myosin-binding protein-C (MyBP-C) is bound to the myosin thick filament and is predicted to stabilize myosin heads in a docked position against the thick filament, which limits crossbridge formation. Here, we use the homozygous Mybpc2 knockout (C2-/-) mouse line to remove the fast-isoform MyBP-C from fast skeletal muscle and then conduct mechanical functional studies in parallel with small-angle X-ray diffraction to evaluate the myofilament structure. We report that C2-/- fibers present deficits in force production and calcium sensitivity. Structurally, passive C2-/- fibers present altered sarcomere length-independent and -dependent regulation of myosin head conformations, with a shift of myosin heads towards actin. At shorter sarcomere lengths, the thin filament is axially extended in C2-/-, which we hypothesize is due to increased numbers of low-level crossbridges. These findings provide testable mechanisms to explain the etiology of debilitating diseases associated with MyBP-C.
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Affiliation(s)
- Anthony L Hessel
- Institute of Physiology II, University of Muenster, Muenster, Germany.
| | - Michel N Kuehn
- Institute of Physiology II, University of Muenster, Muenster, Germany
| | - Seong-Won Han
- Institute of Physiology II, University of Muenster, Muenster, Germany
| | - Weikang Ma
- BioCAT, Department of Biology, Illinois Institute of Technology, Chicago, USA
| | - Thomas C Irving
- BioCAT, Department of Biology, Illinois Institute of Technology, Chicago, USA
| | - Brent A Momb
- Department of Kinesiology, University of Massachusetts-Amherst, Amherst, MA, USA
| | - Taejeong Song
- Center for Cardiovascular Research, Division of Cardiovascular Health and Disease, Department of Internal Medicine, University of Cincinnati, Cincinnati, OH, USA
| | - Sakthivel Sadayappan
- Center for Cardiovascular Research, Division of Cardiovascular Health and Disease, Department of Internal Medicine, University of Cincinnati, Cincinnati, OH, USA
| | - Wolfgang A Linke
- Institute of Physiology II, University of Muenster, Muenster, Germany
| | - Bradley M Palmer
- Department of Molecular Physiology and Biophysics, University of Vermont, Burlington, VT, USA.
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20
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Mead AF, Wood NB, Nelson SR, Palmer BM, Yang L, Previs SB, Ploysangngam A, Kennedy GG, McAdow JF, Tremble SM, Cipolla MJ, Ebert AM, Johnson AN, Gurnett CA, Previs MJ, Warshaw DM. Functional role of myosin-binding protein H in thick filaments of developing vertebrate fast-twitch skeletal muscle. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.10.593199. [PMID: 38798399 PMCID: PMC11118323 DOI: 10.1101/2024.05.10.593199] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2024]
Abstract
Myosin-binding protein H (MyBP-H) is a component of the vertebrate skeletal muscle sarcomere with sequence and domain homology to myosin-binding protein C (MyBP-C). Whereas skeletal muscle isoforms of MyBP-C (fMyBP-C, sMyBP-C) modulate muscle contractility via interactions with actin thin filaments and myosin motors within the muscle sarcomere "C-zone," MyBP-H has no known function. This is in part due to MyBP-H having limited expression in adult fast-twitch muscle and no known involvement in muscle disease. Quantitative proteomics reported here reveal MyBP-H is highly expressed in prenatal rat fast-twitch muscles and larval zebrafish, suggesting a conserved role in muscle development, and promoting studies to define its function. We take advantage of the genetic control of the zebrafish model and a combination of structural, functional, and biophysical techniques to interrogate the role of MyBP-H. Transgenic, FLAG-tagged MyBP-H or fMyBP-C both localize to the C-zones in larval myofibers, whereas genetic depletion of endogenous MyBP-H or fMyBP-C leads to increased accumulation of the other, suggesting competition for C-zone binding sites. Does MyBP-H modulate contractility from the C-zone? Globular domains critical to MyBP-C's modulatory functions are absent from MyBP-H, suggesting MyBP-H may be functionally silent. However, our results suggest an active role. Small angle x-ray diffraction of intact larval tails revealed MyBP-H contributes to the compression of the myofilament lattice accompanying stretch or contraction, while in vitro motility experiments indicate MyBP-H shares MyBP-C's capacity as a molecular "brake". These results provide new insights and raise questions about the role of the C-zone during muscle development.
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Affiliation(s)
- Andrew F. Mead
- Department of Molecular Physiology and Biophysics, Larner College of Medicine, University of Vermont, Burlington, VT 05405
- Cardiovascular Research Institute, University of Vermont, Burlington, VT 05405
| | - Neil B. Wood
- Department of Molecular Physiology and Biophysics, Larner College of Medicine, University of Vermont, Burlington, VT 05405
| | - Shane R. Nelson
- Department of Molecular Physiology and Biophysics, Larner College of Medicine, University of Vermont, Burlington, VT 05405
- Cardiovascular Research Institute, University of Vermont, Burlington, VT 05405
| | - Bradley M. Palmer
- Department of Molecular Physiology and Biophysics, Larner College of Medicine, University of Vermont, Burlington, VT 05405
- Cardiovascular Research Institute, University of Vermont, Burlington, VT 05405
| | - Lin Yang
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY 11973
| | - Samantha Beck Previs
- Department of Molecular Physiology and Biophysics, Larner College of Medicine, University of Vermont, Burlington, VT 05405
- Cardiovascular Research Institute, University of Vermont, Burlington, VT 05405
| | - Angela Ploysangngam
- Department of Molecular Physiology and Biophysics, Larner College of Medicine, University of Vermont, Burlington, VT 05405
| | - Guy G. Kennedy
- Department of Molecular Physiology and Biophysics, Larner College of Medicine, University of Vermont, Burlington, VT 05405
| | - Jennifer F. McAdow
- Department of Neurlogical Sciences, Larner College of Medicine, University of Vermont, Burlington, VT 05405
| | - Sarah M. Tremble
- Department of Electrical and Biomedical Engineering, College of Engineering and Mathematical Sciences, University of Vermont, Burlington, VT 05405
| | - Marilyn J. Cipolla
- Department of Electrical and Biomedical Engineering, College of Engineering and Mathematical Sciences, University of Vermont, Burlington, VT 05405
- Department of Neurology, Washington University School of Medicine in St. Louis, St. Louis, MO 63110
| | - Alicia M. Ebert
- Department of Biology, College of Arts and Sciences, University of Vermont, Burlington, VT 05405
| | - Aaron N. Johnson
- Department of Developmental Biology, Washington University School of Medicine in St. Louis, St. Louis, MO 63110
| | - Christina A. Gurnett
- Department of Developmental Biology, Washington University School of Medicine in St. Louis, St. Louis, MO 63110
| | - Michael J. Previs
- Department of Molecular Physiology and Biophysics, Larner College of Medicine, University of Vermont, Burlington, VT 05405
- Cardiovascular Research Institute, University of Vermont, Burlington, VT 05405
| | - David M. Warshaw
- Department of Molecular Physiology and Biophysics, Larner College of Medicine, University of Vermont, Burlington, VT 05405
- Cardiovascular Research Institute, University of Vermont, Burlington, VT 05405
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21
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Horsthemke M, Arnaud CA, Hanley PJ. Are the class 18 myosins Myo18A and Myo18B specialist sarcomeric proteins? Front Physiol 2024; 15:1401717. [PMID: 38784114 PMCID: PMC11112018 DOI: 10.3389/fphys.2024.1401717] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2024] [Accepted: 04/22/2024] [Indexed: 05/25/2024] Open
Abstract
Initially, the two members of class 18 myosins, Myo18A and Myo18B, appeared to exhibit highly divergent functions, complicating the assignment of class-specific functions. However, the identification of a striated muscle-specific isoform of Myo18A, Myo18Aγ, suggests that class 18 myosins may have evolved to complement the functions of conventional class 2 myosins in sarcomeres. Indeed, both genes, Myo18a and Myo18b, are predominantly expressed in the heart and somites, precursors of skeletal muscle, of developing mouse embryos. Genetic deletion of either gene in mice is embryonic lethal and is associated with the disorganization of cardiac sarcomeres. Moreover, Myo18Aγ and Myo18B localize to sarcomeric A-bands, albeit the motor (head) domains of these unconventional myosins have been both deduced and biochemically demonstrated to exhibit negligible ATPase activity, a hallmark of motor proteins. Instead, Myo18Aγ and Myo18B presumably coassemble with thick filaments and provide structural integrity and/or internal resistance through interactions with F-actin and/or other proteins. In addition, Myo18Aγ and Myo18B may play distinct roles in the assembly of myofibrils, which may arise from actin stress fibers containing the α-isoform of Myo18A, Myo18Aα. The β-isoform of Myo18A, Myo18Aβ, is similar to Myo18Aα, except that it lacks the N-terminal extension, and may serve as a negative regulator through heterodimerization with either Myo18Aα or Myo18Aγ. In this review, we contend that Myo18Aγ and Myo18B are essential for myofibril structure and function in striated muscle cells, while α- and β-isoforms of Myo18A play diverse roles in nonmuscle cells.
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Affiliation(s)
- Markus Horsthemke
- IMM Institute for Molecular Medicine, HMU Health and Medical University Potsdam, Potsdam, Germany
| | - Charles-Adrien Arnaud
- IMM Institute for Molecular Medicine, HMU Health and Medical University Potsdam, Potsdam, Germany
- Department of Medicine, Science Faculty, MSB Medical School Berlin, Berlin, Germany
| | - Peter J. Hanley
- IMM Institute for Molecular Medicine, HMU Health and Medical University Potsdam, Potsdam, Germany
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22
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Buvoli M, Wilson GC, Buvoli A, Gugel JF, Hau A, Bönnemann CG, Paradas C, Ryba DM, Woulfe KC, Walker LA, Buvoli T, Ochala J, Leinwand LA. A Laing distal myopathy-associated proline substitution in the β-myosin rod perturbs myosin cross-bridging activity. J Clin Invest 2024; 134:e172599. [PMID: 38690726 PMCID: PMC11060730 DOI: 10.1172/jci172599] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Accepted: 03/11/2024] [Indexed: 05/03/2024] Open
Abstract
Proline substitutions within the coiled-coil rod region of the β-myosin gene (MYH7) are the predominant mutations causing Laing distal myopathy (MPD1), an autosomal dominant disorder characterized by progressive weakness of distal/proximal muscles. We report that the MDP1 mutation R1500P, studied in what we believe to be the first mouse model for the disease, adversely affected myosin motor activity despite being in the structural rod domain that directs thick filament assembly. Contractility experiments carried out on isolated mutant muscles, myofibrils, and myofibers identified muscle fatigue and weakness phenotypes, an increased rate of actin-myosin detachment, and a conformational shift of the myosin heads toward the more reactive disordered relaxed (DRX) state, causing hypercontractility and greater ATP consumption. Similarly, molecular analysis of muscle biopsies from patients with MPD1 revealed a significant increase in sarcomeric DRX content, as observed in a subset of myosin motor domain mutations causing hypertrophic cardiomyopathy. Finally, oral administration of MYK-581, a small molecule that decreases the population of heads in the DRX configuration, significantly improved the limited running capacity of the R1500P-transgenic mice and corrected the increased DRX state of the myofibrils from patients. These studies provide evidence of the molecular pathogenesis of proline rod mutations and lay the groundwork for the therapeutic advancement of myosin modulators.
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Affiliation(s)
- Massimo Buvoli
- Department of Molecular, Cellular and Developmental Biology, and
- BioFrontiers Institute, Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, Colorado, USA
| | - Genevieve C.K. Wilson
- Department of Molecular, Cellular and Developmental Biology, and
- BioFrontiers Institute, Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, Colorado, USA
| | - Ada Buvoli
- Department of Molecular, Cellular and Developmental Biology, and
- BioFrontiers Institute, Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, Colorado, USA
| | - Jack F. Gugel
- Department of Molecular, Cellular and Developmental Biology, and
- BioFrontiers Institute, Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, Colorado, USA
| | - Abbi Hau
- Centre of Human and Applied Physiological Sciences, School of Basic and Medical Biosciences, Faculty of Life Sciences and Medicine, and
- Randall Centre for Cell and Molecular Biophysics, School of Basic and Medical Biosciences, Faculty of Life Sciences and Medicine, Guy’s Campus, King’s College London, London, United Kingdom
| | - Carsten G. Bönnemann
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke (NINDS), NIH, Bethesda, Maryland, USA
| | - Carmen Paradas
- Neuromuscular Unit, Department of Neurology, Instituto de Biomedicina de Sevilla (IBIS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Sevilla, Spain
| | | | - Kathleen C. Woulfe
- Division of Cardiology, Department of Medicine, University of Colorado, Denver, Colorado, USA
| | - Lori A. Walker
- Division of Cardiology, Department of Medicine, University of Colorado, Denver, Colorado, USA
| | - Tommaso Buvoli
- Department of Mathematics, Tulane University, New Orleans, Louisiana, USA
| | - Julien Ochala
- Centre of Human and Applied Physiological Sciences, School of Basic and Medical Biosciences, Faculty of Life Sciences and Medicine, and
- Randall Centre for Cell and Molecular Biophysics, School of Basic and Medical Biosciences, Faculty of Life Sciences and Medicine, Guy’s Campus, King’s College London, London, United Kingdom
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Leslie A. Leinwand
- Department of Molecular, Cellular and Developmental Biology, and
- BioFrontiers Institute, Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, Colorado, USA
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23
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Morales PN, Coons AN, Koopman AJ, Patel S, Chase PB, Parvatiyar MS, Pinto JR. Post-translational modifications of vertebrate striated muscle myosin heavy chains. Cytoskeleton (Hoboken) 2024:10.1002/cm.21857. [PMID: 38587113 PMCID: PMC11458826 DOI: 10.1002/cm.21857] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Revised: 03/06/2024] [Accepted: 03/25/2024] [Indexed: 04/09/2024]
Abstract
Post-translational modifications (PTMs) play a crucial role in regulating the function of many sarcomeric proteins, including myosin. Myosins comprise a family of motor proteins that play fundamental roles in cell motility in general and muscle contraction in particular. A myosin molecule consists of two myosin heavy chains (MyHCs) and two pairs of myosin light chains (MLCs); two MLCs are associated with the neck region of each MyHC's N-terminal head domain, while the two MyHC C-terminal tails form a coiled-coil that polymerizes with other MyHCs to form the thick filament backbone. Myosin undergoes extensive PTMs, and dysregulation of these PTMs may lead to abnormal muscle function and contribute to the development of myopathies and cardiovascular disorders. Recent studies have uncovered the significance of PTMs in regulating MyHC function and showed how these PTMs may provide additional modulation of contractile processes. Here, we discuss MyHC PTMs that have been biochemically and/or functionally studied in mammals' and rodents' striated muscle. We have identified hotspots or specific regions in three isoforms of myosin (MYH2, MYH6, and MYH7) where the prevalence of PTMs is more frequent and could potentially play a significant role in fine-tuning the activity of these proteins.
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Affiliation(s)
- Paula Nieto Morales
- Department of Biomedical Sciences, Florida State University College of Medicine, Tallahassee, FL 32306 USA
| | - Arianna N. Coons
- Department of Biological Science, Florida State University, Tallahassee, FL 32306 USA
| | - Amelia J. Koopman
- Department of Biological Science, Florida State University, Tallahassee, FL 32306 USA
| | - Sonu Patel
- Department of Health, Nutrition and Food Sciences, Florida State University, Tallahassee, FL 32306 USA
| | - P. Bryant Chase
- Department of Biological Science, Florida State University, Tallahassee, FL 32306 USA
| | - Michelle S. Parvatiyar
- Department of Health, Nutrition and Food Sciences, Florida State University, Tallahassee, FL 32306 USA
| | - Jose R. Pinto
- Department of Biomedical Sciences, Florida State University College of Medicine, Tallahassee, FL 32306 USA
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24
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Hessel AL, Engels NM, Kuehn MN, Nissen D, Sadler RL, Ma W, Irving TC, Linke WA, Harris SP. Myosin-binding protein C regulates the sarcomere lattice and stabilizes the OFF states of myosin heads. Nat Commun 2024; 15:2628. [PMID: 38521794 PMCID: PMC10960836 DOI: 10.1038/s41467-024-46957-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Accepted: 03/15/2024] [Indexed: 03/25/2024] Open
Abstract
Muscle contraction is produced via the interaction of myofilaments and is regulated so that muscle performance matches demand. Myosin-binding protein C (MyBP-C) is a long and flexible protein that is tightly bound to the thick filament at its C-terminal end (MyBP-CC8C10), but may be loosely bound at its middle- and N-terminal end (MyBP-CC1C7) to myosin heads and/or the thin filament. MyBP-C is thought to control muscle contraction via the regulation of myosin motors, as mutations lead to debilitating disease. We use a combination of mechanics and small-angle X-ray diffraction to study the immediate and selective removal of the MyBP-CC1C7 domains of fast MyBP-C in permeabilized skeletal muscle. We show that cleavage leads to alterations in crossbridge kinetics and passive structural signatures of myofilaments that are indicative of a shift of myosin heads towards the ON state, highlighting the importance of MyBP-CC1C7 to myofilament force production and regulation.
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Affiliation(s)
- Anthony L Hessel
- Institute of Physiology II, University of Muenster, Muenster, Germany.
- Accelerated Muscle Biotechnologies Consultants, Boston, MA, USA.
| | - Nichlas M Engels
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ, USA
| | - Michel N Kuehn
- Institute of Physiology II, University of Muenster, Muenster, Germany
- Accelerated Muscle Biotechnologies Consultants, Boston, MA, USA
| | - Devin Nissen
- BioCAT, Department of Biology, Illinois Institute of Technology, Chicago, IL, USA
| | - Rachel L Sadler
- Department of Physiology, University of Arizona, Tucson, AZ, USA
| | - Weikang Ma
- BioCAT, Department of Biology, Illinois Institute of Technology, Chicago, IL, USA
| | - Thomas C Irving
- BioCAT, Department of Biology, Illinois Institute of Technology, Chicago, IL, USA
| | - Wolfgang A Linke
- Institute of Physiology II, University of Muenster, Muenster, Germany
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25
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Risi CM, Belknap B, Atherton J, Coscarella IL, White HD, Bryant Chase P, Pinto JR, Galkin VE. Troponin Structural Dynamics in the Native Cardiac Thin Filament Revealed by Cryo Electron Microscopy. J Mol Biol 2024; 436:168498. [PMID: 38387550 PMCID: PMC11007730 DOI: 10.1016/j.jmb.2024.168498] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2024] [Revised: 02/07/2024] [Accepted: 02/15/2024] [Indexed: 02/24/2024]
Abstract
Cardiac muscle contraction occurs due to repetitive interactions between myosin thick and actin thin filaments (TF) regulated by Ca2+ levels, active cross-bridges, and cardiac myosin-binding protein C (cMyBP-C). The cardiac TF (cTF) has two nonequivalent strands, each comprised of actin, tropomyosin (Tm), and troponin (Tn). Tn shifts Tm away from myosin-binding sites on actin at elevated Ca2+ levels to allow formation of force-producing actomyosin cross-bridges. The Tn complex is comprised of three distinct polypeptides - Ca2+-binding TnC, inhibitory TnI, and Tm-binding TnT. The molecular mechanism of their collective action is unresolved due to lack of comprehensive structural information on Tn region of cTF. C1 domain of cMyBP-C activates cTF in the absence of Ca2+ to the same extent as rigor myosin. Here we used cryo-EM of native cTFs to show that cTF Tn core adopts multiple structural conformations at high and low Ca2+ levels and that the two strands are structurally distinct. At high Ca2+ levels, cTF is not entirely activated by Ca2+ but exists in either partially or fully activated state. Complete dissociation of TnI C-terminus is required for full activation. In presence of cMyBP-C C1 domain, Tn core adopts a fully activated conformation, even in absence of Ca2+. Our data provide a structural description for the requirement of myosin to fully activate cTFs and explain increased affinity of TnC to Ca2+ in presence of active cross-bridges. We suggest that allosteric coupling between Tn subunits and Tm is required to control actomyosin interactions.
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Affiliation(s)
- Cristina M Risi
- Department of Physiological Sciences, Eastern Virginia Medical School, Norfolk, VA 23507, USA
| | - Betty Belknap
- Department of Physiological Sciences, Eastern Virginia Medical School, Norfolk, VA 23507, USA
| | - Jennifer Atherton
- Department of Physiological Sciences, Eastern Virginia Medical School, Norfolk, VA 23507, USA
| | - Isabella Leite Coscarella
- Department of Biomedical Sciences, Florida State University College of Medicine, Tallahassee, FL, USA
| | - Howard D White
- Department of Physiological Sciences, Eastern Virginia Medical School, Norfolk, VA 23507, USA
| | - P Bryant Chase
- Department of Biological Science, Florida State University, Tallahassee, FL, USA
| | - Jose R Pinto
- Department of Biomedical Sciences, Florida State University College of Medicine, Tallahassee, FL, USA
| | - Vitold E Galkin
- Department of Physiological Sciences, Eastern Virginia Medical School, Norfolk, VA 23507, USA.
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26
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Kelly CM, Martin JL, Previs MJ. Myosin folding boosts solubility in cardiac muscle sarcomeres. JCI Insight 2024; 9:e178131. [PMID: 38483507 PMCID: PMC11141871 DOI: 10.1172/jci.insight.178131] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2023] [Accepted: 03/05/2024] [Indexed: 04/23/2024] Open
Abstract
The polymerization of myosin molecules into thick filaments in muscle sarcomeres is essential for cardiac contractility, with the attenuation of interactions between the heads of myosin molecules within the filaments being proposed to result in hypercontractility, as observed in hypertrophic cardiomyopathy (HCM). However, experimental evidence demonstrates that the structure of these giant macromolecular complexes is highly dynamic, with molecules exchanging between the filaments and a pool of soluble molecules on the minute timescale. Therefore, we sought to test the hypothesis that the enhancement of interactions between the heads of myosin molecules within thick filaments limits the mobility of myosin by taking advantage of mavacamten, a small molecule approved for the treatment of HCM. Myosin molecules were labeled in vivo with a green fluorescent protein (GFP) and imaged in intact hearts using multiphoton microscopy. Treatment of the intact hearts with mavacamten resulted in an unexpected > 5-fold enhancement in GFP-myosin mobility within the sarcomere. In vitro biochemical assays suggested that mavacamten enhanced the mobility of GFP-myosin by increasing the solubility of myosin molecules, through the stabilization of a compact/folded conformation of the molecules, once disassociated from the thick filaments. These findings provide alternative insight into the mechanisms by which molecules exchange into and out of thick filaments and have implications for how mavacamten may affect cardiac contractility.
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Affiliation(s)
- Colleen M Kelly
- Molecular Physiology and Biophysics Department, Larner College of Medicine, University of Vermont, Burlington, Vermont, USA
| | - Jody L Martin
- Department of Pharmacology, University of California, Davis, Davis, California, USA
| | - Michael J Previs
- Molecular Physiology and Biophysics Department, Larner College of Medicine, University of Vermont, Burlington, Vermont, USA
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27
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Luther PK, Marston SB. Complex architecture of cardiac muscle thick filaments revealed. Trends Pharmacol Sci 2024; 45:191-192. [PMID: 38302402 DOI: 10.1016/j.tips.2024.01.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Revised: 01/10/2024] [Accepted: 01/17/2024] [Indexed: 02/03/2024]
Abstract
Muscle contraction is orchestrated by the well-understood thin filaments and the markedly complex thick filaments. Studies by Dutta et al. and Tamborrini et al., discussed here, have unravelled the structure of the mammalian heart thick filament in exquisite near-atomic detail and pave the way for understanding physiological modulation pathways and mutation-induced dysfunction and for designing potential drugs to modify defects.
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Affiliation(s)
- Pradeep K Luther
- Cardiac Function Section, NHLI, Imperial College London, Hammersmith Campus, ICTEM Building, Du Cane Road, London, W12 0NN, UK.
| | - Steve B Marston
- Cardiac Function Section, NHLI, Imperial College London, Hammersmith Campus, ICTEM Building, Du Cane Road, London, W12 0NN, UK
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28
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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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29
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Chen L, Liu J, Rastegarpouyani H, Janssen PML, Pinto JR, Taylor KA. Structure of mavacamten-free human cardiac thick filaments within the sarcomere by cryoelectron tomography. Proc Natl Acad Sci U S A 2024; 121:e2311883121. [PMID: 38386705 PMCID: PMC10907299 DOI: 10.1073/pnas.2311883121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2023] [Accepted: 01/18/2024] [Indexed: 02/24/2024] Open
Abstract
Heart muscle has the unique property that it can never rest; all cardiomyocytes contract with each heartbeat which requires a complex control mechanism to regulate cardiac output to physiological requirements. Changes in calcium concentration regulate the thin filament activation. A separate but linked mechanism regulates the thick filament activation, which frees sufficient myosin heads to bind the thin filament, thereby producing the required force. Thick filaments contain additional nonmyosin proteins, myosin-binding protein C and titin, the latter being the protein that transmits applied tension to the thick filament. How these three proteins interact to control thick filament activation is poorly understood. Here, we show using 3-D image reconstruction of frozen-hydrated human cardiac muscle myofibrils lacking exogenous drugs that the thick filament is structured to provide three levels of myosin activation corresponding to the three crowns of myosin heads in each 429Å repeat. In one crown, the myosin heads are almost completely activated and disordered. In another crown, many myosin heads are inactive, ordered into a structure called the interacting heads motif. At the third crown, the myosin heads are ordered into the interacting heads motif, but the stability of that motif is affected by myosin-binding protein C. We think that this hierarchy of control explains many of the effects of length-dependent activation as well as stretch activation in cardiac muscle control.
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Affiliation(s)
- Liang Chen
- Institute of Molecular Biophysics, Florida State University, Tallahassee, FL32306
| | - Jun Liu
- Microbial Sciences Institute, Yale University, West Haven, CT06516
- Department of Microbial Pathogenesis, Yale School of Medicine, New Haven, CT06536
| | - Hosna Rastegarpouyani
- Institute of Molecular Biophysics, Florida State University, Tallahassee, FL32306
- Department of Biological Science, Florida State University, Tallahassee, FL32306
| | - Paul M. L. Janssen
- Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, OH43210
| | - Jose R. Pinto
- Department of Biomedical Sciences, Florida State College of Medicine, Florida State University, Tallahassee, FL32306
| | - Kenneth A. Taylor
- Institute of Molecular Biophysics, Florida State University, Tallahassee, FL32306
- Department of Biological Science, Florida State University, Tallahassee, FL32306
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30
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Ma W, del Rio CL, Qi L, Prodanovic M, Mijailovich S, Zambataro C, Gong H, Shimkunas R, Gollapudi S, Nag S, Irving TC. Myosin in autoinhibited off state(s), stabilized by mavacamten, can be recruited in response to inotropic interventions. Proc Natl Acad Sci U S A 2024; 121:e2314914121. [PMID: 38346202 PMCID: PMC10895252 DOI: 10.1073/pnas.2314914121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Accepted: 01/08/2024] [Indexed: 02/15/2024] Open
Abstract
Mavacamten is a FDA-approved small-molecule therapeutic designed to regulate cardiac function at the sarcomere level by selectively but reversibly inhibiting the enzymatic activity of myosin. It shifts myosin toward ordered off states close to the thick filament backbone. It remains elusive whether these myosin heads in the off state(s) can be recruited in response to physiological stimuli when required to boost cardiac output. We show that cardiac myosins stabilized in these off state(s) by mavacamten are recruitable by 1) Ca2+, 2) increased chronotropy [heart rate (HR)], 3) stretch, and 4) β-adrenergic (β-AR) stimulation, all known physiological inotropic interventions. At the molecular level, we show that Ca2+ increases myosin ATPase activity by shifting mavacamten-stabilized myosin heads from the inactive super-relaxed state to the active disordered relaxed state. At the myofilament level, both Ca2+ and passive lengthening can shift mavacamten-ordered off myosin heads from positions close to the thick filament backbone to disordered on states closer to the thin filaments. In isolated rat cardiomyocytes, increased stimulation rates enhanced shortening fraction in mavacamten-treated cells. This observation was confirmed in vivo in telemetered rats, where left-ventricular dP/dtmax, an index of inotropy, increased with HR in mavacamten-treated animals. Finally, we show that β-AR stimulation in vivo increases left-ventricular function and stroke volume in the setting of mavacamten. Our data demonstrate that the mavacamten-promoted off states of myosin in the thick filament are at least partially activable, thus preserving cardiac reserve mechanisms.
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Affiliation(s)
- Weikang Ma
- Biophysics Collaborative Access Team, Department of Biology, Illinois Institute of Technology, Chicago, IL60616
- Center for Synchrotron Radiation Research and Instrumentation, Illinois Institute of Technology, Chicago, IL60616
| | - Carlos L. del Rio
- Cardiovascular Drug Discovery, Bristol Myers Squibb, Brisbane, CA94005
- Cardiac Consulting, San Mateo, CA94010
| | - Lin Qi
- Department of Biology, Illinois Institute of Technology, Chicago, IL60616
| | - Momcilo Prodanovic
- Institute for Information Technologies, University of Kragujevac, Kragujevac34000, Serbia
- FilamenTech, Inc., Newtown, MA02458
| | | | | | - Henry Gong
- Department of Biology, Illinois Institute of Technology, Chicago, IL60616
| | - Rafael Shimkunas
- Cardiovascular Drug Discovery, Bristol Myers Squibb, Brisbane, CA94005
| | - Sampath Gollapudi
- Cardiovascular Drug Discovery, Bristol Myers Squibb, Brisbane, CA94005
| | - Suman Nag
- Cardiovascular Drug Discovery, Bristol Myers Squibb, Brisbane, CA94005
| | - Thomas C. Irving
- Biophysics Collaborative Access Team, Department of Biology, Illinois Institute of Technology, Chicago, IL60616
- Center for Synchrotron Radiation Research and Instrumentation, Illinois Institute of Technology, Chicago, IL60616
- Department of Biology, Illinois Institute of Technology, Chicago, IL60616
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31
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Abstract
Force generation in striated muscle is primarily controlled by structural changes in the actin-containing thin filaments triggered by an increase in intracellular calcium concentration. However, recent studies have elucidated a new class of regulatory mechanisms, based on the myosin-containing thick filament, that control the strength and speed of contraction by modulating the availability of myosin motors for the interaction with actin. This review summarizes the mechanisms of thin and thick filament activation that regulate the contractility of skeletal and cardiac muscle. A novel dual-filament paradigm of muscle regulation is emerging, in which the dynamics of force generation depends on the coordinated activation of thin and thick filaments. We highlight the interfilament signaling pathways based on titin and myosin-binding protein-C that couple thin and thick filament regulatory mechanisms. This dual-filament regulation mediates the length-dependent activation of cardiac muscle that underlies the control of the cardiac output in each heartbeat.
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Affiliation(s)
- Elisabetta Brunello
- Randall Centre for Cell and Molecular Biophysics, School of Basic and Medical Biosciences and British Heart Foundation Centre of Research Excellence, King's College London, London, United Kingdom; ,
| | - Luca Fusi
- Randall Centre for Cell and Molecular Biophysics, School of Basic and Medical Biosciences and British Heart Foundation Centre of Research Excellence, King's College London, London, United Kingdom; ,
- Centre for Human and Applied Physiological Sciences, School of Basic and Medical Biosciences, King's College London, London, United Kingdom
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32
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Jani VP, Song T, Gao C, Gong H, Sadayappan S, Kass DA, Irving TC, Ma W. The structural OFF and ON states of myosin can be decoupled from the biochemical super- and disordered-relaxed states. PNAS NEXUS 2024; 3:pgae039. [PMID: 38328779 PMCID: PMC10849796 DOI: 10.1093/pnasnexus/pgae039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/14/2023] [Accepted: 01/19/2024] [Indexed: 02/09/2024]
Abstract
There is a growing awareness that both thick-filament and classical thin-filament regulations play central roles in modulating muscle contraction. Myosin ATPase assays have demonstrated that under relaxed conditions, myosin may reside either in a high-energy-consuming disordered-relaxed (DRX) state available for binding actin to generate force or in an energy-sparing super-relaxed (SRX) state unavailable for actin binding. X-ray diffraction studies have shown that the majority of myosin heads are in a quasi-helically ordered OFF state in a resting muscle and that this helical ordering is lost when myosin heads are turned ON for contraction. It has been assumed that myosin heads in SRX and DRX states are equivalent to the OFF and ON states, respectively, and the terms have been used interchangeably. In this study, we use X-ray diffraction and ATP turnover assays to track the structural and biochemical transitions of myosin heads, respectively, induced with either omecamtiv mecarbil (OM) or piperine in relaxed porcine myocardium. We find that while OM and piperine induce dramatic shifts of myosin heads from the OFF to the ON state, there are no appreciable changes in the population of myosin heads in the SRX and DRX states in both unloaded and loaded preparations. Our results show that biochemically defined SRX and DRX can be decoupled from structurally defined OFF and ON states. In summary, while SRX/DRX and OFF/ON transitions can be correlated in some cases, these two phenomena are measured using different approaches, reflect different properties of the thick filament, and should be investigated and interpreted separately.
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Affiliation(s)
- Vivek P Jani
- Department of Biomedical Engineering, The Johns Hopkins School of Medicine, Baltimore, MD 21205, USA
- Division of Cardiology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Taejeong Song
- Division of Cardiovascular Health and Disease, Department of Internal Medicine, University of Cincinnati, Cincinnati, OH 45229, USA
| | - Chengqian Gao
- College of Basic Medical Sciences, Dalian Medical University, Dalian, Liaoning 116044, China
| | - Henry Gong
- Department of Biology, Illinois Institute of Technology, Chicago, IL 60616, USA
| | - Sakthivel Sadayappan
- Division of Cardiovascular Health and Disease, Department of Internal Medicine, University of Cincinnati, Cincinnati, OH 45229, USA
| | - David A Kass
- Department of Biomedical Engineering, The Johns Hopkins School of Medicine, Baltimore, MD 21205, USA
- Division of Cardiology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Thomas C Irving
- Department of Biology, Illinois Institute of Technology, Chicago, IL 60616, USA
- Center for Synchrotron Radiation Research and Instrumentation, Illinois Institute of Technology, Chicago, IL 60616, USA
| | - Weikang Ma
- Department of Biology, Illinois Institute of Technology, Chicago, IL 60616, USA
- Center for Synchrotron Radiation Research and Instrumentation, Illinois Institute of Technology, Chicago, IL 60616, USA
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33
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Bao Y, Jia F, Li M, Xu R, Xie Y, Zhang F, Guo J. Characterizing the Molecular Mechanism of the Lethal C423D Mutation in FgMyoI: A Molecular Perspective. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2024; 72:1539-1549. [PMID: 38226494 DOI: 10.1021/acs.jafc.3c08648] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/17/2024]
Abstract
The lethal mutation C423D in Fusarium graminearum myosin I (FgMyoI) occurs close to the binding pocket of the allosteric inhibitor phenamacril and causes severe inhibition on mycelial growth of F. graminearum strain PH-1. Here, based on extensive Gaussian accelerated molecular dynamics simulations and wet experiments, we elucidate the underlying molecular mechanism of the abnormal functioning of the FgMyoIC423D mutant at the atomistic level. Our results suggest that the damaging mutation C423D exhibits a synergistic allosteric inhibition mechanism similar to but more robust than that of phenamacril, including effects on the active site and actin binding. Unlike phenamacril-induced closure of Switch2, the mutation results in unfolding of the N-terminal relay helix with a partially opened Switch2 and blocks the structural rearrangement of the relay/SH1 helices, impairing the proper initiation of the recovery stroke. Due to the significant influence of C423D mutation on the function of FgMyoI, designing covalent inhibitors targeting this site holds tremendous potential.
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Affiliation(s)
- Yiqiong Bao
- College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Fangying Jia
- College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China
| | - Mengrong Li
- College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Ran Xu
- Centre for Artificial Intelligence Driven Drug Discovery, Faculty of Applied Sciences, Macao Polytechnic University, Macao 999078, China
| | - Yanjie Xie
- College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Feng Zhang
- College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China
| | - Jingjing Guo
- Centre for Artificial Intelligence Driven Drug Discovery, Faculty of Applied Sciences, Macao Polytechnic University, Macao 999078, China
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Pearce A, Ponnam S, Holt MR, Randall T, Beckingham R, Kho AL, Kampourakis T, Ehler E. Missense mutations in the central domains of cardiac myosin binding protein-C and their potential contribution to hypertrophic cardiomyopathy. J Biol Chem 2024; 300:105511. [PMID: 38042491 PMCID: PMC10772716 DOI: 10.1016/j.jbc.2023.105511] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Revised: 11/05/2023] [Accepted: 11/20/2023] [Indexed: 12/04/2023] Open
Abstract
Myosin binding protein-C (MyBP-C) is a multidomain protein that regulates muscle contraction. Mutations in MYBPC3, the gene encoding for the cardiac variant (henceforth called cMyBP-C), are amongst the most frequent causes of hypertrophic cardiomyopathy. Most mutations lead to a truncated version of cMyBP-C, which is most likely unstable. However, missense mutations have also been reported, which tend to cluster in the central domains of the cMyBP-C molecule. This suggests that these central domains are more than just a passive spacer between the better characterized N- and C-terminal domains. Here, we investigated the potential impact of four different missense mutations, E542Q, G596R, N755K, and R820Q, which are spread over the domains C3 to C6, on the function of MyBP-C on both the isolated protein level and in cardiomyocytes in vitro. Effect on domain stability, interaction with thin filaments, binding to myosin, and subcellular localization behavior were assessed. Our studies show that these missense mutations result in slightly different phenotypes at the molecular level, which are mutation specific. The expected functional readout of each mutation provides a valid explanation for why cMyBP-C fails to work as a brake in the regulation of muscle contraction, which eventually results in a hypertrophic cardiomyopathy phenotype. We conclude that missense mutations in cMyBP-C must be evaluated in context of their domain localization, their effect on interaction with thin filaments and myosin, and their effect on protein stability to explain how they lead to disease.
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Affiliation(s)
- Amy Pearce
- School of Cardiovascular and Metabolic Medicine and Sciences, King's College London, London, United Kingdom; British Heart Foundation Centre of Research Excellence, King's College London, London, United Kingdom
| | - Saraswathi Ponnam
- British Heart Foundation Centre of Research Excellence, King's College London, London, United Kingdom; Randall Centre for Cell and Molecular Biophysics (School of Basic and Biosciences), King's College London, London, United Kingdom
| | - Mark R Holt
- School of Cardiovascular and Metabolic Medicine and Sciences, King's College London, London, United Kingdom; British Heart Foundation Centre of Research Excellence, King's College London, London, United Kingdom
| | - Thomas Randall
- School of Cardiovascular and Metabolic Medicine and Sciences, King's College London, London, United Kingdom; British Heart Foundation Centre of Research Excellence, King's College London, London, United Kingdom
| | - Rylan Beckingham
- School of Cardiovascular and Metabolic Medicine and Sciences, King's College London, London, United Kingdom; British Heart Foundation Centre of Research Excellence, King's College London, London, United Kingdom
| | - Ay Lin Kho
- British Heart Foundation Centre of Research Excellence, King's College London, London, United Kingdom; Randall Centre for Cell and Molecular Biophysics (School of Basic and Biosciences), King's College London, London, United Kingdom
| | - Thomas Kampourakis
- British Heart Foundation Centre of Research Excellence, King's College London, London, United Kingdom; Randall Centre for Cell and Molecular Biophysics (School of Basic and Biosciences), King's College London, London, United Kingdom
| | - Elisabeth Ehler
- School of Cardiovascular and Metabolic Medicine and Sciences, King's College London, London, United Kingdom; British Heart Foundation Centre of Research Excellence, King's College London, London, United Kingdom; Randall Centre for Cell and Molecular Biophysics (School of Basic and Biosciences), King's College London, London, United Kingdom.
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35
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Lim GB. Revealing the structure of the cardiac myosin filament. Nat Rev Cardiol 2024; 21:7. [PMID: 37964080 DOI: 10.1038/s41569-023-00960-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2023]
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36
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Kochurova AM, Beldiia EA, Nefedova VV, Ryabkova NS, Yampolskaya DS, Matyushenko AM, Bershitsky SY, Kopylova GV, Shchepkin DV. N-Terminal Fragment of Cardiac Myosin Binding Protein C Modulates Cooperative Mechanisms of Thin Filament Activation in Atria and Ventricles. BIOCHEMISTRY. BIOKHIMIIA 2024; 89:116-129. [PMID: 38467549 DOI: 10.1134/s0006297924010073] [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: 11/16/2023] [Revised: 12/09/2023] [Accepted: 12/11/2023] [Indexed: 03/13/2024]
Abstract
Cardiac myosin binding protein C (cMyBP-C) is one of the essential control components of the myosin cross-bridge cycle. The C-terminal part of cMyBP-C is located on the surface of the thick filament, and its N-terminal part interacts with actin, myosin, and tropomyosin, affecting both kinetics of the ATP hydrolysis cycle and lifetime of the cross-bridge, as well as calcium regulation of the actin-myosin interaction, thereby modulating contractile function of myocardium. The role of cMyBP-C in atrial contraction has not been practically studied. We examined effect of the N-terminal C0-C1-m-C2 (C0-C2) fragment of cMyBP-C on actin-myosin interaction using ventricular and atrial myosin in an in vitro motility assay. The C0-C2 fragment of cMyBP-C significantly reduced the maximum sliding velocity of thin filaments on both myosin isoforms and increased the calcium sensitivity of the actin-myosin interaction. The C0-C2 fragment had different effects on the kinetics of ATP and ADP exchange, increasing the affinity of ventricular myosin for ADP and decreasing the affinity of atrial myosin. The effect of the C0-C2 fragment on the activation of the thin filament depended on the myosin isoforms. Atrial myosin activates the thin filament less than ventricular myosin, and the C0-C2 fragment makes these differences in the myosin isoforms more pronounced.
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Affiliation(s)
- Anastasia M Kochurova
- Institute of Immunology and Physiology, Russian Academy of Sciences, Yekaterinburg, 620049, Russia
| | - Evgenia A Beldiia
- Institute of Immunology and Physiology, Russian Academy of Sciences, Yekaterinburg, 620049, Russia
- Ural Federal University, Ekaterinburg, 620002, Russia
| | - Victoria V Nefedova
- Bach Institute of Biochemistry, Research Center of Biotechnology, Russian Academy of Sciences, Moscow, 119071, Russia
| | - Natalia S Ryabkova
- Department of Biochemistry, Faculty of Biology, Lomonosov Moscow State University, Moscow, 119234, Russia
- HyTest Ltd., Turku, 20520, Finland
| | - Daria S Yampolskaya
- Bach Institute of Biochemistry, Research Center of Biotechnology, Russian Academy of Sciences, Moscow, 119071, Russia
| | - Alexander M Matyushenko
- Bach Institute of Biochemistry, Research Center of Biotechnology, Russian Academy of Sciences, Moscow, 119071, Russia
| | - Sergey Y Bershitsky
- Institute of Immunology and Physiology, Russian Academy of Sciences, Yekaterinburg, 620049, Russia
| | - Galina V Kopylova
- Institute of Immunology and Physiology, Russian Academy of Sciences, Yekaterinburg, 620049, Russia
| | - Daniil V Shchepkin
- Institute of Immunology and Physiology, Russian Academy of Sciences, Yekaterinburg, 620049, Russia.
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Duno-Miranda S, Nelson SR, Rasicci DV, Bodt SL, Cirilo JA, Vang D, Sivaramakrishnan S, Yengo CM, Warshaw DM. Tail Length and E525K Dilated Cardiomyopathy Mutant Alter Human β-Cardiac Myosin Super-Relaxed State. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.07.570656. [PMID: 38105932 PMCID: PMC10723396 DOI: 10.1101/2023.12.07.570656] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2023]
Abstract
Dilated cardiomyopathy (DCM) is characterized by impaired cardiac function due to myocardial hypo-contractility and is associated with point mutations in β-cardiac myosin, the molecular motor that powers cardiac contraction. Myocardial function can be modulated through sequestration of myosin motors into an auto-inhibited "super relaxed" state (SRX), which is further stabilized by a structural state known as the "Interacting Heads Motif" (IHM). Therefore, hypo-contractility of DCM myocardium may result from: 1) reduced function of individual myosin, and/or; 2) decreased myosin availability due to increased IHM/SRX stabilization. To define the molecular impact of an established DCM myosin mutation, E525K, we characterized the biochemical and mechanical activity of wild-type (WT) and E525K human β-cardiac myosin constructs that differed in the length of their coiled-coil tail, which dictates their ability to form the IHM/SRX state. Single-headed (S1) and a short-tailed, double-headed (2HEP) myosin constructs exhibited low (~10%) IHM/SRX content, actin-activated ATPase activity of ~5s-1 and fast velocities in unloaded motility assays (~2000nm/s). Double-headed, longer-tailed (15HEP, 25HEP) constructs exhibited higher IHM/SRX content (~90%), and reduced actomyosin ATPase (<1s-1) and velocity (~800nm/s). A simple analytical model suggests that reduced velocities may be attributed to IHM/SRXdependent sequestration of myosin heads. Interestingly, the E525K 15HEP and 25HEP mutants showed no apparent impact on velocity or actomyosin ATPase at low ionic strength. However, at higher ionic strength, the E525K mutation stabilized the IHM/SRX state. Therefore, the E525K-associated DCM human cardiac hypo-contractility may be attributable to reduced myosin head availability caused by enhanced IHM/SRX stability.
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Affiliation(s)
- Sebastian Duno-Miranda
- Department of Molecular Physiology and Biophysics, Cardiovascular Research Institute, University of Vermont, Burlington, Vermont
| | - Shane R. Nelson
- Department of Molecular Physiology and Biophysics, Cardiovascular Research Institute, University of Vermont, Burlington, Vermont
| | - David V. Rasicci
- Department of Cellular and Molecular Physiology, Penn State College of Medicine, Hershey, Pennsylvania
| | - Skylar L.M. Bodt
- Department of Cellular and Molecular Physiology, Penn State College of Medicine, Hershey, Pennsylvania
| | - Joseph A. Cirilo
- Department of Cellular and Molecular Physiology, Penn State College of Medicine, Hershey, Pennsylvania
| | - Duha Vang
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, Minnesota
| | - Sivaraj Sivaramakrishnan
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, Minnesota
| | - Christopher M. Yengo
- Department of Cellular and Molecular Physiology, Penn State College of Medicine, Hershey, Pennsylvania
| | - David M. Warshaw
- Department of Molecular Physiology and Biophysics, Cardiovascular Research Institute, University of Vermont, Burlington, Vermont
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38
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Kelly CM, Martin JL, Coseno M, Previs MJ. Visualization of cardiac thick filament dynamics in ex vivo heart preparations. J Mol Cell Cardiol 2023; 185:88-98. [PMID: 37923195 PMCID: PMC10959293 DOI: 10.1016/j.yjmcc.2023.10.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Revised: 10/27/2023] [Accepted: 10/30/2023] [Indexed: 11/07/2023]
Abstract
RATIONALE Cardiac muscle cells are terminally differentiated after birth and must beat continually throughout one's lifetime. This mechanical process is driven by the sliding of actin-based thin filaments along myosin-based thick filaments, organized within sarcomeres. Despite costly energetic demand, the half-life of the proteins that comprise the cardiac thick filaments is ∼10 days, with individual molecules being replaced stochastically, by unknown mechanisms. OBJECTIVES To allow for the stochastic replacement of molecules, we hypothesized that the structure of thick filaments must be highly dynamic in vivo. METHODS AND RESULTS To test this hypothesis in adult mouse hearts, we replaced a fraction of the endogenous myosin regulatory light chain (RLC), a component of thick filaments, with GFP-labeled RLC by adeno-associated viral (AAV) transduction. The RLC-GFP was properly localized to the heads of the myosin molecules within thick filaments in ex vivo heart preparations and had no effect on heart size or actin filament siding in vitro. However, the localization of the RLC-GFP molecules was highly mobile, changing its position within the sarcomere on the minute timescale, when quantified by fluorescence recovery after photobleaching (FRAP) using multiphoton microscopy. Interestingly, RLC-GFP mobility was restricted to within the boundaries of single sarcomeres. When cardiomyocytes were lysed, the RLC-GFP remained strongly bound to myosin heavy chain, and the intact myosin molecules adopted a folded, compact configuration, when disassociated from the filaments at physiological ionic conditions. CONCLUSIONS These data demonstrate that the structure of the thick filament is highly dynamic in the intact heart, with a rate of molecular exchange into and out of thick filaments that is ∼1500 times faster than that required for the replacement of molecules through protein synthesis or degradation.
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Affiliation(s)
- Colleen M Kelly
- Molecular Physiology and Biophysics Department, University of Vermont, Larner College of Medicine, Burlington, VT 05405, United States of America
| | - Jody L Martin
- Department of Pharmacology, University of California, Davis, Davis, CA 90095, United States of America
| | - Molly Coseno
- Fluidic Analytics, The Paddocks Business Centre, Cambridge CB1 8DH, United Kingdom
| | - Michael J Previs
- Molecular Physiology and Biophysics Department, University of Vermont, Larner College of Medicine, Burlington, VT 05405, United States of America.
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39
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Tamborrini D, Wang Z, Wagner T, Tacke S, Stabrin M, Grange M, Kho AL, Rees M, Bennett P, Gautel M, Raunser S. Structure of the native myosin filament in the relaxed cardiac sarcomere. Nature 2023; 623:863-871. [PMID: 37914933 PMCID: PMC10665186 DOI: 10.1038/s41586-023-06690-5] [Citation(s) in RCA: 36] [Impact Index Per Article: 36.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Accepted: 09/28/2023] [Indexed: 11/03/2023]
Abstract
The thick filament is a key component of sarcomeres, the basic units of striated muscle1. Alterations in thick filament proteins are associated with familial hypertrophic cardiomyopathy and other heart and muscle diseases2. Despite the central importance of the thick filament, its molecular organization remains unclear. Here we present the molecular architecture of native cardiac sarcomeres in the relaxed state, determined by cryo-electron tomography. Our reconstruction of the thick filament reveals the three-dimensional organization of myosin, titin and myosin-binding protein C (MyBP-C). The arrangement of myosin molecules is dependent on their position along the filament, suggesting specialized capacities in terms of strain susceptibility and force generation. Three pairs of titin-α and titin-β chains run axially along the filament, intertwining with myosin tails and probably orchestrating the length-dependent activation of the sarcomere. Notably, whereas the three titin-α chains run along the entire length of the thick filament, titin-β chains do not. The structure also demonstrates that MyBP-C bridges thin and thick filaments, with its carboxy-terminal region binding to the myosin tails and directly stabilizing the OFF state of the myosin heads in an unforeseen manner. These results provide a foundation for future research investigating muscle disorders involving sarcomeric components.
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Affiliation(s)
- Davide Tamborrini
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Zhexin Wang
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany
- Structural Studies Division, MRC Laboratory of Molecular Biology, Cambridge, UK
| | - Thorsten Wagner
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Sebastian Tacke
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Markus Stabrin
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Michael Grange
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany
- Structural Biology, The Rosalind Franklin Institute, Didcot, UK
| | - Ay Lin Kho
- Randall Centre for Cell and Molecular Biophysics, School of Basic and Medical Biosciences, Kings College London BHF Centre of Research Excellence, London, UK
| | - Martin Rees
- Randall Centre for Cell and Molecular Biophysics, School of Basic and Medical Biosciences, Kings College London BHF Centre of Research Excellence, London, UK
| | - Pauline Bennett
- Randall Centre for Cell and Molecular Biophysics, School of Basic and Medical Biosciences, Kings College London BHF Centre of Research Excellence, London, UK
| | - Mathias Gautel
- Randall Centre for Cell and Molecular Biophysics, School of Basic and Medical Biosciences, Kings College London BHF Centre of Research Excellence, London, UK
| | - Stefan Raunser
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany.
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40
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Knight PJ. Getting to the heart of thick-filament structure. Nature 2023; 623:703-704. [PMID: 37914878 DOI: 10.1038/d41586-023-03307-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2023]
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