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, 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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2
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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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3
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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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4
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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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5
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Leduc-Pessah H, Smith IC, Kernohan KD, Sampaio M, Melkus G, Strasser L, Chisholm C, Huang L, Hanes I, Tran MA, Venkateswaran S, Muir K, Charlesworth L, Warman-Chardon J. Congenital tremor and myopathy secondary to novel MYBPC1 variant. J Neurol Sci 2024; 457:122864. [PMID: 38185014 DOI: 10.1016/j.jns.2023.122864] [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: 10/24/2023] [Revised: 12/03/2023] [Accepted: 12/28/2023] [Indexed: 01/09/2024]
Abstract
Congenital myopathy with tremor (MYOTREM) is a recently described disorder characterized by mild myopathy and a postural and intention tremor present since early infancy. MYOTREM is associated with pathogenic variants in MYBPC1 which encodes slow myosin-binding protein C, a sarcomere protein with regulatory and structural roles. Here, we describe a family with three generations of variably affected members exhibiting a novel variant in MYBPC1 (c.656 T > C, p.Leu219Pro). Among the unique features of affected family members is the persistence of tremor in sleep. We also present the first muscle magnetic resonance images for this disorder, and report muscle atrophy and fatty infiltration.
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Affiliation(s)
- Heather Leduc-Pessah
- Department of Pediatrics, Neurology, Children's Hospital of Eastern Ontario, Ottawa, ON, Canada.
| | - Ian C Smith
- Ottawa Hospital Research Institute, Ottawa, ON, Canada
| | - Kristin D Kernohan
- Department of Genetics, Children's Hospital of Eastern Ontario, Ottawa, ON, Canada; Newborn Screening, Children's Hospital of Eastern Ontario, Ottawa, ON, Canada
| | - Marcos Sampaio
- Department of Radiology, The Ottawa Hospital, Ottawa, ON, Canada
| | - Gerd Melkus
- Department of Radiology, The Ottawa Hospital, Ottawa, ON, Canada
| | - Lauren Strasser
- Department of Pediatrics, Neurology, Children's Hospital of Eastern Ontario, Ottawa, ON, Canada
| | - Caitlin Chisholm
- Department of Genetics, Children's Hospital of Eastern Ontario, Ottawa, ON, Canada
| | - Lijia Huang
- Department of Genetics, Children's Hospital of Eastern Ontario, Ottawa, ON, Canada
| | - Ilana Hanes
- Department of Pediatrics, Neurology, Children's Hospital of Eastern Ontario, Ottawa, ON, Canada
| | - My-An Tran
- Department of Pediatrics, Neurology, Children's Hospital of Eastern Ontario, Ottawa, ON, Canada
| | - Sunita Venkateswaran
- Department of Pediatrics, Neurology, Children's Hospital of Eastern Ontario, Ottawa, ON, Canada
| | - Katherine Muir
- Department of Pediatrics, Neurology, Children's Hospital of Eastern Ontario, Ottawa, ON, Canada
| | | | - Jodi Warman-Chardon
- Ottawa Hospital Research Institute, Ottawa, ON, Canada; Department of Genetics, Children's Hospital of Eastern Ontario, Ottawa, ON, Canada; Department of Medicine, Neurology, The Ottawa Hospital, Ottawa, ON, Canada
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6
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Barefield DY, Tonino P, Woulfe KC, Rahmanseresht S, O’Leary TS, Burnham HV, Wasserstrom JA, Kirk JA, Previs MJ, Granzier HL, McNally EM. Myosin-binding protein H-like regulates myosin-binding protein distribution and function in atrial cardiomyocytes. Proc Natl Acad Sci U S A 2023; 120:e2314920120. [PMID: 38091294 PMCID: PMC10741380 DOI: 10.1073/pnas.2314920120] [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: 09/01/2023] [Accepted: 10/25/2023] [Indexed: 12/18/2023] Open
Abstract
Mutations in atrial-enriched genes can cause a primary atrial myopathy that can contribute to overall cardiovascular dysfunction. MYBPHL encodes myosin-binding protein H-like (MyBP-HL), an atrial sarcomere protein that shares domain homology with the carboxy-terminus of cardiac myosin-binding protein-C (cMyBP-C). The function of MyBP-HL and the relationship between MyBP-HL and cMyBP-C is unknown. To decipher the roles of MyBP-HL, we used structured illumination microscopy, immuno-electron microscopy, and mass spectrometry to establish the localization and stoichiometry of MyBP-HL. We found levels of cMyBP-C, a major regulator of myosin function, were half as abundant compared to levels in the ventricle. In genetic mouse models, loss of MyBP-HL doubled cMyBP-C abundance in the atria, and loss of cMyBP-C doubled MyBP-HL abundance in the atria. Structured illumination microscopy showed that both proteins colocalize in the C-zone of the A-band, with MyBP-HL enriched closer to the M-line. Immuno-electron microscopy of mouse atria showed MyBP-HL strongly localized 161 nm from the M-line, consistent with localization to the third 43 nm repeat of myosin heads. Both cMyBP-C and MyBP-HL had less-defined sarcomere localization in the atria compared to ventricle, yet areas with the expected 43 nm repeat distance were observed for both proteins. Isometric force measurements taken from control and Mybphl null single atrial myofibrils revealed that loss of Mybphl accelerated the linear phase of relaxation. These findings support a mechanism where MyBP-HL regulates cMyBP-C abundance to alter the kinetics of sarcomere relaxation in atrial sarcomeres.
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Affiliation(s)
- David Y. Barefield
- Center for Genetic Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL60611
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, IL60153
| | - Paola Tonino
- Department of Cell and Molecular Medicine, University of Arizona, Tucson, AZ85724
| | - Kathleen C. Woulfe
- Division of Cardiology, Department of Medicine, University of Colorado, Anschutz Medical Campus, Aurora, CO80045
| | - Sheema Rahmanseresht
- Department of Molecular Physiology and Biophysics, University of Vermont, Burlington, VT01655
| | - Thomas S. O’Leary
- Department of Molecular Physiology and Biophysics, University of Vermont, Burlington, VT01655
| | - Hope V. Burnham
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, IL60153
| | - J. Andrew Wasserstrom
- Department of Medicine and The Feinberg Cardiovascular and Renal Institute, Northwestern University Feinberg School of Medicine, Chicago, IL60611
| | - Jonathan A. Kirk
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, IL60153
| | - Michael J. Previs
- Department of Molecular Physiology and Biophysics, University of Vermont, Burlington, VT01655
| | - Henk L. Granzier
- Department of Cell and Molecular Medicine, University of Arizona, Tucson, AZ85724
| | - Elizabeth M. McNally
- Center for Genetic Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL60611
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7
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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: 32] [Impact Index Per Article: 32.0] [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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8
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Dutta D, Nguyen V, Campbell KS, Padrón R, Craig R. Cryo-EM structure of the human cardiac myosin filament. Nature 2023; 623:853-862. [PMID: 37914935 PMCID: PMC10846670 DOI: 10.1038/s41586-023-06691-4] [Citation(s) in RCA: 28] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Accepted: 09/28/2023] [Indexed: 11/03/2023]
Abstract
Pumping of the heart is powered by filaments of the motor protein myosin that pull on actin filaments to generate cardiac contraction. In addition to myosin, the filaments contain cardiac myosin-binding protein C (cMyBP-C), which modulates contractility in response to physiological stimuli, and titin, which functions as a scaffold for filament assembly1. Myosin, cMyBP-C and titin are all subject to mutation, which can lead to heart failure. Despite the central importance of cardiac myosin filaments to life, their molecular structure has remained a mystery for 60 years2. Here we solve the structure of the main (cMyBP-C-containing) region of the human cardiac filament using cryo-electron microscopy. The reconstruction reveals the architecture of titin and cMyBP-C and shows how myosin's motor domains (heads) form three different types of motif (providing functional flexibility), which interact with each other and with titin and cMyBP-C to dictate filament architecture and function. The packing of myosin tails in the filament backbone is also resolved. The structure suggests how cMyBP-C helps to generate the cardiac super-relaxed state3; how titin and cMyBP-C may contribute to length-dependent activation4; and how mutations in myosin and cMyBP-C might disturb interactions, causing disease5,6. The reconstruction resolves past uncertainties and integrates previous data on cardiac muscle structure and function. It provides a new paradigm for interpreting structural, physiological and clinical observations, and for the design of potential therapeutic drugs.
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Affiliation(s)
- Debabrata Dutta
- Division of Cell Biology and Imaging, Department of Radiology, University of Massachusetts Chan Medical School, Worcester, MA, USA.
| | - Vu Nguyen
- Division of Cell Biology and Imaging, Department of Radiology, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Kenneth S Campbell
- Department of Physiology and Division of Cardiovascular Medicine, University of Kentucky, Lexington, KY, USA
| | - Raúl Padrón
- Division of Cell Biology and Imaging, Department of Radiology, University of Massachusetts Chan Medical School, Worcester, MA, USA.
| | - Roger Craig
- Division of Cell Biology and Imaging, Department of Radiology, University of Massachusetts Chan Medical School, Worcester, MA, USA.
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9
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Hessel AL, Engels NM, Kuehn M, Nissen D, Sadler RL, Ma W, Irving TC, Linke WA, Harris SP. Myosin-binding protein C forms C-links and stabilizes OFF states of myosin. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.10.556972. [PMID: 37745361 PMCID: PMC10515747 DOI: 10.1101/2023.09.10.556972] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/26/2023]
Abstract
Contraction force in muscle is produced by the interaction of myosin motors in the thick filaments and actin in the thin filaments and is fine-tuned by other proteins such as myosin-binding protein C (MyBP-C). One form of control is through the regulation of myosin heads between an ON and OFF state in passive sarcomeres, which leads to their ability or inability to interact with the thin filaments during contraction, respectively. MyBP-C is a flexible and long protein that is tightly bound to the thick filament at its C-terminal end but may be loosely bound at its middle- and N-terminal end (MyBP-CC1C7). Under considerable debate is whether the MyBP-CC1C7 domains directly regulate myosin head ON/OFF states, and/or link thin filaments ("C-links"). Here, we used 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. After cleavage, the thin filaments were significantly shorter, a result consistent with direct interactions of MyBP-C with thin filaments thus confirming C-links. Ca2+ sensitivity was reduced at shorter sarcomere lengths, and crossbridge kinetics were increased across sarcomere lengths at submaximal activation levels, demonstrating a role in crossbridge kinetics. Structural signatures of the thick filaments suggest that cleavage also shifted myosin heads towards the ON state - a marker that typically indicates increased Ca2+ sensitivity but that may account for increased crossbridge kinetics at submaximal Ca2+ and/or a change in the force transmission pathway. Taken together, we conclude that MyBP-CC1C7 domains play an important role in contractile performance which helps explain why mutations in these domains often lead to debilitating diseases.
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Affiliation(s)
- Anthony L Hessel
- Institute of Physiology II, University of Muenster; Muenster, Germany
| | - Nichlas M Engels
- Department of Cellular and Molecular Medicine, University of Arizona; Tucson, AZ, USA
| | - Michel Kuehn
- Institute of Physiology II, University of Muenster; Muenster, Germany
| | - 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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10
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Ma W, Lee KH, Delligatti CE, Davis MT, Zheng Y, Gong H, Kirk JA, Craig R, Irving T. The structural and functional integrities of porcine myocardium are mostly preserved by cryopreservation. J Gen Physiol 2023; 155:e202313345. [PMID: 37398997 PMCID: PMC10318404 DOI: 10.1085/jgp.202313345] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Revised: 05/05/2023] [Accepted: 06/21/2023] [Indexed: 07/04/2023] Open
Abstract
Structural and functional studies of heart muscle are important to gain insights into the physiological bases of cardiac muscle contraction and the pathological bases of heart disease. While fresh muscle tissue works best for these kinds of studies, this is not always practical to obtain, especially for heart tissue from large animal models and humans. Conversely, tissue banks of frozen human hearts are available and could be a tremendous resource for translational research. It is not well understood, however, how liquid nitrogen freezing and cryostorage may impact the structural integrity of myocardium from large mammals. In this study, we directly compared the structural and functional integrity of never-frozen to previously frozen porcine myocardium to investigate the consequences of freezing and cryostorage. X-ray diffraction measurements from hydrated tissue under near-physiological conditions and electron microscope images from chemically fixed porcine myocardium showed that prior freezing has only minor effects on structural integrity of the muscle. Furthermore, mechanical studies similarly showed no significant differences in contractile capabilities of porcine myocardium with and without freezing and cryostorage. These results demonstrate that liquid nitrogen preservation is a practical approach for structural and functional studies of myocardium.
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Affiliation(s)
- Weikang Ma
- BioCAT, Department of Biology, Illinois Institute of Technology, Chicago, IL, USA
| | - Kyoung Hwan Lee
- Electron Microscopy Facility, UMass Chan Medical School, Worcester, MA, USA
| | | | - M. Therese Davis
- Department of Cell and Molecular Physiology, Loyola University Chicago, Chicago, IL, USA
| | - Yahan Zheng
- College of Basic Medical Sciences, Dalian Medical University, Dalian, China
| | - Henry Gong
- BioCAT, Department of Biology, Illinois Institute of Technology, Chicago, IL, USA
| | - Jonathan A. Kirk
- Department of Cell and Molecular Physiology, Loyola University Chicago, Chicago, IL, USA
| | - Roger Craig
- Division of Cell Biology and Imaging, Department of Radiology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Thomas Irving
- BioCAT, Department of Biology, Illinois Institute of Technology, Chicago, IL, USA
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11
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Huang X, Torre I, Chiappi M, Yin Z, Vydyanath A, Cao S, Raschdorf O, Beeby M, Quigley B, de Tombe PP, Liu J, Morris EP, Luther PK. Cryo-electron tomography of intact cardiac muscle reveals myosin binding protein-C linking myosin and actin filaments. J Muscle Res Cell Motil 2023; 44:165-178. [PMID: 37115473 PMCID: PMC10542292 DOI: 10.1007/s10974-023-09647-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2022] [Accepted: 03/29/2023] [Indexed: 04/29/2023]
Abstract
Myosin binding protein C (MyBP-C) is an accessory protein of the thick filament in vertebrate cardiac muscle arranged over 9 stripes of intervals of 430 Å in each half of the A-band in the region called the C-zone. Mutations in cardiac MyBP-C are a leading cause of hypertrophic cardiomyopathy the mechanism of which is unknown. It is a rod-shaped protein composed of 10 or 11 immunoglobulin- or fibronectin-like domains labelled C0 to C10 which binds to the thick filament via its C-terminal region. MyBP-C regulates contraction in a phosphorylation dependent fashion that may be through binding of its N-terminal domains with myosin or actin. Understanding the 3D organisation of MyBP-C in the sarcomere environment may provide new light on its function. We report here the fine structure of MyBP-C in relaxed rat cardiac muscle by cryo-electron tomography and subtomogram averaging of refrozen Tokuyasu cryosections. We find that on average MyBP-C connects via its distal end to actin across a disc perpendicular to the thick filament. The path of MyBP-C suggests that the central domains may interact with myosin heads. Surprisingly MyBP-C at Stripe 4 is different; it has weaker density than the other stripes which could result from a mainly axial or wavy path. Given that the same feature at Stripe 4 can also be found in several mammalian cardiac muscles and in some skeletal muscles, our finding may have broader implication and significance. In the D-zone, we show the first demonstration of myosin crowns arranged on a uniform 143 Å repeat.
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Affiliation(s)
- Xinrui Huang
- Department of Biochemistry and Biophysics, School of Basic Medical Sciences, Peking University, Beijing, 100191, China
- Department of Microbial Pathogenesis, Yale School of Medicine, New Haven, CT, 06516, USA
| | - Iratxe Torre
- National Heart and Lung Institute, Imperial College London, London, SW7 2AZ, UK
| | - Michele Chiappi
- National Heart and Lung Institute, Imperial College London, London, SW7 2AZ, UK
| | - Zhan Yin
- National Heart and Lung Institute, Imperial College London, London, SW7 2AZ, UK
| | - Anupama Vydyanath
- National Heart and Lung Institute, Imperial College London, London, SW7 2AZ, UK
| | - Shuangyi Cao
- National Heart and Lung Institute, Imperial College London, London, SW7 2AZ, UK
| | | | - Morgan Beeby
- Department of Life Sciences, Imperial College London, London, SW7 2AZ, UK
| | - Bonnie Quigley
- Department of Life Sciences, Imperial College London, London, SW7 2AZ, UK
| | - Pieter P de Tombe
- National Heart and Lung Institute, Imperial College London, London, SW7 2AZ, UK
- Department of Physiology and Biophysics, University of Illinois at Chicago, 835 S. Wolcott Ave, Chicago, IL, 60612, USA
- Phymedexp, Université de Montpellier, Inserm, CNRS, Montpellier, France
| | - Jun Liu
- Department of Microbial Pathogenesis, Yale School of Medicine, New Haven, CT, 06516, USA
| | - Edward P Morris
- Division of Structural Biology, Institute of Cancer Research, London, SW3 6JB, UK
- School of Molecular Biosciences, University of Glasgow, Garscube Campus, Jarrett Building, 351, Bearsden Road, Glasgow, G61 1QH, UK
| | - Pradeep K Luther
- National Heart and Lung Institute, Imperial College London, London, SW7 2AZ, UK.
- Cardiac Function Section, National Heart and Lung Institute, Imperial College London, London, SW7 2AZ, UK.
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12
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Hoh JFY. Developmental, physiologic and phylogenetic perspectives on the expression and regulation of myosin heavy chains in mammalian skeletal muscles. J Comp Physiol B 2023:10.1007/s00360-023-01499-0. [PMID: 37277594 DOI: 10.1007/s00360-023-01499-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Revised: 05/05/2023] [Accepted: 05/12/2023] [Indexed: 06/07/2023]
Abstract
The kinetics of myosin controls the speed and power of muscle contraction. Mammalian skeletal muscles express twelve kinetically different myosin heavy chain (MyHC) genes which provides a wide range of muscle speeds to meet different functional demands. Myogenic progenitors from diverse craniofacial and somitic mesoderm specify muscle allotypes with different repertoires for MyHC expression. This review provides a brief synopsis on the historical and current views on how cell lineage, neural impulse patterns, and thyroid hormone influence MyHC gene expression in muscles of the limb allotype during development and in adult life and the molecular mechanisms thereof. During somitic myogenesis, embryonic and foetal myoblast lineages form slow and fast primary and secondary myotube ontotypes which respond differently to postnatal neural and thyroidal influences to generate fully differentiated fibre phenotypes. Fibres of a given phenotype may arise from myotubes of different ontotypes which retain their capacity to respond differently to neural and thyroidal influences during postnatal life. This gives muscles physiological plasticity to adapt to fluctuations in thyroid hormone levels and patterns of use. The kinetics of MyHC isoforms vary inversely with animal body mass. Fast 2b fibres are specifically absent in muscles involved in elastic energy saving in hopping marsupials and generally absent in large eutherian mammals. Changes in MyHC expression are viewed in the context of the physiology of the whole animal. The roles of myoblast lineage and thyroid hormone in regulating MyHC gene expression are phylogenetically the most ancient while that of neural impulse patterns the most recent.
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Affiliation(s)
- Joseph Foon Yoong Hoh
- Discipline of Physiology, School of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, 2006, Australia.
- , PO Box 152, Killara, NSW, 2071, Australia.
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13
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Dutta D, Nguyen V, Campbell KS, Padrón R, Craig R. Cryo-EM structure of the human cardiac myosin filament. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.11.536274. [PMID: 37090534 PMCID: PMC10120621 DOI: 10.1101/2023.04.11.536274] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/25/2023]
Abstract
Pumping of the heart is powered by filaments of the motor protein myosin, which pull on actin filaments to generate cardiac contraction. In addition to myosin, the filaments contain cardiac myosin-binding protein C (cMyBP-C), which modulates contractility in response to physiological stimuli, and titin, which functions as a scaffold for filament assembly 1 . Myosin, cMyBP-C and titin are all subject to mutation, which can lead to heart failure. Despite the central importance of cardiac myosin filaments to life, their molecular structure has remained a mystery for 60 years 2 . Here, we have solved the structure of the main (cMyBP-C-containing) region of the human cardiac filament to 6 Å resolution by cryo-EM. The reconstruction reveals the architecture of titin and cMyBP-C for the first time, and shows how myosin's motor domains (heads) form 3 different types of motif (providing functional flexibility), which interact with each other and with specific domains of titin and cMyBP-C to dictate filament architecture and regulate function. A novel packing of myosin tails in the filament backbone is also resolved. The structure suggests how cMyBP-C helps generate the cardiac super-relaxed state 3 , how titin and cMyBP-C may contribute to length-dependent activation 4 , and how mutations in myosin and cMyBP-C might disrupt interactions, causing disease 5, 6 . A similar structure is likely in vertebrate skeletal myosin filaments. The reconstruction resolves past uncertainties, and integrates previous data on cardiac muscle structure and function. It provides a new paradigm for interpreting structural, physiological and clinical observations, and for the design of potential therapeutic drugs.
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14
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Titin activates myosin filaments in skeletal muscle by switching from an extensible spring to a mechanical rectifier. Proc Natl Acad Sci U S A 2023; 120:e2219346120. [PMID: 36812205 PMCID: PMC9992839 DOI: 10.1073/pnas.2219346120] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/24/2023] Open
Abstract
Titin is a molecular spring in parallel with myosin motors in each muscle half-sarcomere, responsible for passive force development at sarcomere length (SL) above the physiological range (>2.7 μm). The role of titin at physiological SL is unclear and is investigated here in single intact muscle cells of the frog (Rana esculenta), by combining half-sarcomere mechanics and synchrotron X-ray diffraction in the presence of 20 μM para-nitro-blebbistatin, which abolishes the activity of myosin motors and maintains them in the resting state even during activation of the cell by electrical stimulation. We show that, during cell activation at physiological SL, titin in the I-band switches from an SL-dependent extensible spring (OFF-state) to an SL-independent rectifier (ON-state) that allows free shortening while resisting stretch with an effective stiffness of ~3 pN nm-1 per half-thick filament. In this way, I-band titin efficiently transmits any load increase to the myosin filament in the A-band. Small-angle X-ray diffraction signals reveal that, with I-band titin ON, the periodic interactions of A-band titin with myosin motors alter their resting disposition in a load-dependent manner, biasing the azimuthal orientation of the motors toward actin. This work sets the stage for future investigations on scaffold and mechanosensing-based signaling functions of titin in health and disease.
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15
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Hessel AL, Kuehn M, Palmer BM, Nissen D, Mishra D, Joumaa V, Freundt J, Ma W, Nishikawa KC, Irving T, Linke WA. The distinctive mechanical and structural signatures of residual force enhancement in myofibers. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.19.529125. [PMID: 36865266 PMCID: PMC9980001 DOI: 10.1101/2023.02.19.529125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
Abstract
In muscle, titin proteins connect myofilaments together and are thought to be critical for contraction, especially during residual force enhancement (RFE) when force is elevated after an active stretch. We investigated titin's function during contraction using small-angle X-ray diffraction to track structural changes before and after 50% titin cleavage and in the RFE-deficient, mdm titin mutant. We report that the RFE state is structurally distinct from pure isometric contractions, with increased thick filament strain and decreased lattice spacing, most likely caused by elevated titin-based forces. Furthermore, no RFE structural state was detected in mdm muscle. We posit that decreased lattice spacing, increased thick filament stiffness, and increased non-crossbridge forces are the major contributors to RFE. We conclude that titin directly contributes to RFE.
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Affiliation(s)
- Anthony L. Hessel
- Institute of Physiology II, University of Muenster; Muenster, Germany
| | - Michel Kuehn
- Institute of Physiology II, University of Muenster; Muenster, Germany
| | - Bradley M. Palmer
- Department of Molecular Physiology and Biophysics, University of Vermont; Burlington, VT, 05405-1705, USA
| | - Devin Nissen
- BioCAT, Department of Biology, Illinois Institute of Technology; Chicago, IL, USA
| | - Dhruv Mishra
- Department of Biological Sciences, University of Northern Arizona; Flagstaff AZ, USA
| | - Venus Joumaa
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, AB T2N1N4, Canada
| | - Johanna Freundt
- Institute of Physiology II, University of Muenster; Muenster, Germany
| | - Weikang Ma
- BioCAT, Department of Biology, Illinois Institute of Technology; Chicago, IL, USA
| | - Kiisa C. Nishikawa
- Department of Biological Sciences, University of Northern Arizona; Flagstaff AZ, USA
| | - Thomas 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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16
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Hammert WB, Kataoka R, Yamada Y, Seffrin A, Kang A, Seob Song J, Wong V, Spitz RW, Loenneke JP. The Potential Role of the Myosin Head for Strength Gain in Hypertrophied Muscle. Med Hypotheses 2023. [DOI: 10.1016/j.mehy.2023.111023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
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17
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Rosas PC, Solaro RJ. Implications of S-glutathionylation of sarcomere proteins in cardiac disorders, therapies, and diagnosis. Front Cardiovasc Med 2023; 9:1060716. [PMID: 36762302 PMCID: PMC9902711 DOI: 10.3389/fcvm.2022.1060716] [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: 10/03/2022] [Accepted: 12/29/2022] [Indexed: 01/25/2023] Open
Abstract
The discovery that cardiac sarcomere proteins are substrates for S-glutathionylation and that this post-translational modification correlates strongly with diastolic dysfunction led to new concepts regarding how levels of oxidative stress affect the heartbeat. Major sarcomere proteins for which there is evidence of S-glutathionylation include cardiac myosin binding protein C (cMyBP-C), actin, cardiac troponin I (cTnI) and titin. Our hypothesis is that these S-glutathionylated proteins are significant factors in acquired and familial disorders of the heart; and, when released into the serum, provide novel biomarkers. We consider the molecular mechanisms for these effects in the context of recent revelations of how these proteins control cardiac dynamics in close collaboration with Ca2+ fluxes. These revelations were made using powerful approaches and technologies that were focused on thin filaments, thick filaments, and titin filaments. Here we integrate their regulatory processes in the sarcomere as modulated mainly by neuro-humoral control of phosphorylation inasmuch evidence indicates that S-glutathionylation and protein phosphorylation, promoting increased dynamics and modifying the Frank-Starling relation, may be mutually exclusive. Earlier studies demonstrated that in addition to cTnI as a well-established biomarker for cardiac disorders, serum levels of cMyBP-C are also a biomarker for cardiac disorders. We describe recent studies approaching the question of whether serum levels of S-glutathionylated-cMyBP-C could be employed as an important clinical tool in patient stratification, early diagnosis in at risk patients before HFpEF, determination of progression, effectiveness of therapeutic approaches, and as a guide in developing future therapies.
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Affiliation(s)
- Paola C. Rosas
- Department of Pharmacy Practice, College of Pharmacy, Chicago, IL, United States
| | - R. John Solaro
- Department of Physiology and Biophysics, College of Medicine, University of Illinois at Chicago, Chicago, IL, United States
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18
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Sevrieva IR, Ponnam S, Yan Z, Irving M, Kampourakis T, Sun YB. Phosphorylation-dependent interactions of myosin-binding protein C and troponin coordinate the myofilament response to protein kinase A. J Biol Chem 2023; 299:102767. [PMID: 36470422 PMCID: PMC9826837 DOI: 10.1016/j.jbc.2022.102767] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Revised: 11/23/2022] [Accepted: 11/24/2022] [Indexed: 12/12/2022] Open
Abstract
PKA-mediated phosphorylation of sarcomeric proteins enhances heart muscle performance in response to β-adrenergic stimulation and is associated with accelerated relaxation and increased cardiac output for a given preload. At the cellular level, the latter translates to a greater dependence of Ca2+ sensitivity and maximum force on sarcomere length (SL), that is, enhanced length-dependent activation. However, the mechanisms by which PKA phosphorylation of the most notable sarcomeric PKA targets, troponin I (cTnI) and myosin-binding protein C (cMyBP-C), lead to these effects remain elusive. Here, we specifically altered the phosphorylation level of cTnI in heart muscle cells and characterized the structural and functional effects at different levels of background phosphorylation of cMyBP-C and with two different SLs. We found Ser22/23 bisphosphorylation of cTnI was indispensable for the enhancement of length-dependent activation by PKA, as was cMyBP-C phosphorylation. This high level of coordination between cTnI and cMyBP-C may suggest coupling between their regulatory mechanisms. Further evidence for this was provided by our finding that cardiac troponin (cTn) can directly interact with cMyBP-C in vitro, in a phosphorylation- and Ca2+-dependent manner. In addition, bisphosphorylation at Ser22/Ser23 increased Ca2+ sensitivity at long SL in the presence of endogenously phosphorylated cMyBP-C. When cMyBP-C was dephosphorylated, bisphosphorylation of cTnI increased Ca2+ sensitivity and decreased cooperativity at both SLs, which may translate to deleterious effects in physiological settings. Our results could have clinical relevance for disease pathways, where PKA phosphorylation of cTnI may be functionally uncoupled from cMyBP-C phosphorylation due to mutations or haploinsufficiency.
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Affiliation(s)
- Ivanka R Sevrieva
- Randall Centre for Cell and Molecular Biophysics, and British Heart Foundation Centre of Research Excellence, King's College London, London, United Kingdom.
| | - Saraswathi Ponnam
- Randall Centre for Cell and Molecular Biophysics, and British Heart Foundation Centre of Research Excellence, King's College London, London, United Kingdom
| | - Ziqian Yan
- Randall Centre for Cell and Molecular Biophysics, and British Heart Foundation Centre of Research Excellence, King's College London, London, United Kingdom
| | - Malcolm Irving
- Randall Centre for Cell and Molecular Biophysics, and British Heart Foundation Centre of Research Excellence, King's College London, London, United Kingdom
| | - Thomas Kampourakis
- Randall Centre for Cell and Molecular Biophysics, and British Heart Foundation Centre of Research Excellence, King's College London, London, United Kingdom
| | - Yin-Biao Sun
- Randall Centre for Cell and Molecular Biophysics, and British Heart Foundation Centre of Research Excellence, King's College London, London, United Kingdom
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19
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Tomalka A, Heim M, Klotz A, Rode C, Siebert T. Ultrastructural and kinetic evidence support that thick filaments slide through the Z-disc. J R Soc Interface 2022; 19:20220642. [PMID: 36475390 PMCID: PMC9727675 DOI: 10.1098/rsif.2022.0642] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
How myofilaments operate at short mammalian skeletal muscle lengths is unknown. A common assumption is that thick (myosin-containing) filaments get compressed at the Z-disc. We provide ultrastructural evidence of sarcomeres contracting down to 0.44 µm-approximately a quarter of thick filament resting length-in long-lasting contractions while apparently keeping a regular, parallel thick filament arrangement. Sarcomeres produced force at such extremely short lengths. Furthermore, sarcomeres adopted a bimodal length distribution with both modes below lengths where sarcomeres are expected to generate force in classic force-length measurements. Mammalian fibres did not restore resting length but remained short after deactivation, as previously reported for amphibian fibres, and showed increased forces during passive re-elongation. These findings are incompatible with viscoelastic thick filament compression but agree with predictions of a model incorporating thick filament sliding through the Z-disc. This more coherent picture of mechanical mammalian skeletal fibre functioning opens new perspectives on muscle physiology.
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Affiliation(s)
- André Tomalka
- Motion and Exercise Science, University of Stuttgart, Stuttgart, Germany
| | - Maximilian Heim
- Motion and Exercise Science, University of Stuttgart, Stuttgart, Germany
| | - Annika Klotz
- Motion and Exercise Science, University of Stuttgart, Stuttgart, Germany
| | - Christian Rode
- Institute of Sport Science, Department of Biomechanics, University of Rostock, Rostock, Germany
| | - Tobias Siebert
- Motion and Exercise Science, University of Stuttgart, Stuttgart, Germany,Stuttgart Center for Simulation Science, University of Stuttgart, Stuttgart, Germany
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20
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Hessel AL, Ma W, Mazara N, Rice PE, Nissen D, Gong H, Kuehn M, Irving T, Linke WA. Titin force in muscle cells alters lattice order, thick and thin filament protein formation. Proc Natl Acad Sci U S A 2022; 119:e2209441119. [PMID: 36409887 PMCID: PMC9860331 DOI: 10.1073/pnas.2209441119] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Accepted: 10/25/2022] [Indexed: 11/22/2022] Open
Abstract
Skeletal muscle force production is increased at longer compared to shorter muscle lengths because of length-dependent priming of thick filament proteins in the contractile unit before contraction. Using small-angle X-ray diffraction in combination with a mouse model that specifically cleaves the stretch-sensitive titin protein, we found that titin cleavage diminished the length-dependent priming of the thick filament. Strikingly, a titin-sensitive, length-dependent priming was also present in thin filaments, which seems only possible via bridge proteins between thick and thin filaments in resting muscle, potentially myosin-binding protein C. We further show that these bridges can be forcibly ruptured via high-speed stretches. Our results advance a paradigm shift to the fundamental regulation of length-dependent priming, with titin as the key driver.
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Affiliation(s)
- Anthony L. Hessel
- Institute of Physiology II, University of Muenster, Muenster, 48149Germany
| | - Weikang Ma
- BioCAT, Department of Biology, Illinois Institute of Technology, Chicago, IL 60616
| | - Nicole Mazara
- School of Kinesiology, University of British Columbia, Vancouver, CanadaV6T 1Z1
| | - Paige E. Rice
- Department of Biological Sciences, Northern Arizona University, FlagstaffAZ 86011
| | - Devin Nissen
- BioCAT, Department of Biology, Illinois Institute of Technology, Chicago, IL 60616
| | - Henry Gong
- BioCAT, Department of Biology, Illinois Institute of Technology, Chicago, IL 60616
| | - Michel Kuehn
- Institute of Physiology II, University of Muenster, Muenster, 48149Germany
| | - Thomas Irving
- BioCAT, Department of Biology, Illinois Institute of Technology, Chicago, IL 60616
| | - Wolfgang A. Linke
- Institute of Physiology II, University of Muenster, Muenster, 48149Germany
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21
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McMillan SN, Scarff CA. Cryo-electron microscopy analysis of myosin at work and at rest. Curr Opin Struct Biol 2022; 75:102391. [DOI: 10.1016/j.sbi.2022.102391] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2022] [Revised: 04/18/2022] [Accepted: 04/22/2022] [Indexed: 01/01/2023]
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22
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Doh CY, Bharambe N, Holmes JB, Dominic KL, Swanberg CE, Mamidi R, Chen Y, Bandyopadhyay S, Ramachandran R, Stelzer JE. Molecular characterization of linker and loop-mediated structural modulation and hinge motion in the C4-C5 domains of cMyBPC. J Struct Biol 2022; 214:107856. [PMID: 35427781 PMCID: PMC9942529 DOI: 10.1016/j.jsb.2022.107856] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 03/16/2022] [Accepted: 04/01/2022] [Indexed: 10/18/2022]
Abstract
INTRODUCTION The central C4 and C5 domains (C4C5) of cardiac myosin binding protein C (cMyBPC) contain a flexible interdomain linker and a cardiac-isoform specific loop. However, their importance in the functional regulation of cMyBPC has not been extensively studied. METHODS AND RESULTS We expressed recombinant C4C5 proteins with deleted linker and loop regions and performed biophysical experiments to determine each of their structural and dynamic roles. We show that the linker and C5 loop regions modulate the secondary structure and thermal stability of C4C5. Furthermore, we provide evidence through extended molecular dynamics simulations and principle component analyses that C4C5 can adopt a completely bent or latched conformation. The simulation trajectory and interaction network analyses reveal that the completely bent conformation of C4C5 exhibits a specific pattern of residue-level interactions. Therefore, we propose a "hinge-and-latch" mechanism where the linker allows a great degree of flexibility and bending, while the loop aids in achieving a completely bent and latched conformation. Although this may be one of many bent positions that C4C5 can adopt, we illustrate for the first time in molecular detail that this type of large scale conformational change can occur in the central domains of cMyBPC. CONCLUSIONS Our hinge-and-latch mechanism demonstrates that the linker and loop regions participate in dynamic modulation of cMyBPC's motion and global conformation. These structural and dynamic features may contribute to muscle isoform-specific regulation of actomyosin activity, and have potential implications regarding its ability to propagate or retract cMyBPC's regulatory N-terminal domains.
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Affiliation(s)
- Chang Yoon Doh
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Nikhil Bharambe
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Joshua B. Holmes
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Katherine L. Dominic
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Caitlin E. Swanberg
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Ranganath Mamidi
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Yinghua Chen
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Smarajit Bandyopadhyay
- Molecular Biotechnology Core, Shared Laboratory Resources, Cleveland Clinic, Cleveland, OH, USA
| | - Rajesh Ramachandran
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Julian E. Stelzer
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH, USA,Corresponding author at: Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, 2109 Adelbert Rd, Robbins E522, Cleveland, OH 44106, USA. (J.E. Stelzer)
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23
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Touma AM, Tang W, Rasicci DV, Vang D, Rai A, Previs SB, Warshaw DM, Yengo CM, Sivaramakrishnan S. Nanosurfer Assay Dissects β-Cardiac Myosin and Cardiac Myosin-Binding Protein C Interactions. Biophys J 2022; 121:2449-2460. [PMID: 35591788 DOI: 10.1016/j.bpj.2022.05.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Revised: 04/13/2022] [Accepted: 05/13/2022] [Indexed: 11/02/2022] Open
Abstract
Cardiac myosin-binding protein C (cMyBP-C) modulates cardiac contractility through putative interactions with the myosin S2 tail and/or the thin filament. The relative contribution of these binding-partner interactions to cMyBP-C modulatory function remains unclear. Hence, we developed a "nanosurfer" assay as a model system to interrogate these cMyBP-C binding-partner interactions. Synthetic thick filaments were generated using recombinant human β-cardiac myosin subfragments (HMM or S1) attached to DNA nanotubes, with 14 or 28 nm spacing, corresponding to the 14.3 nm myosin spacing in native thick filaments. The nanosurfer assay consists of DNA nanotubes added to the in vitro motility assay so that myosins on the motility surface effectively deliver thin filaments to the DNA nanotubes, enhancing thin filament gliding probability on the DNA nanotubes. Thin filament velocities on nanotubes with either 14 or 28 nm myosin spacing were no different. We then characterized the effects of cMyBP-C on thin filament motility by alternating HMM and cMyBP-C N-terminal fragments (C0-C2 or C1-C2) on nanotubes every 14 nm. Both C0-C2 and C1-C2 reduced thin filament velocity 4-6 fold relative to HMM alone. Similar inhibition occurred using the myosin S1 construct, which lacks the myosin S2 region proposed to interact with cMyBP-C, suggesting that the cMyBP-C N-terminus must interact with other myosin head domains and/or actin to slow thin filament velocity. Thin filament velocity was unaffected by the C0-C1f fragment, which lacks the majority of the M-domain, supporting the importance of this domain for inhibitory interaction(s). A C0-C2 fragment with phosphomimetic replacement in the M-domain showed markedly less inhibition of thin filament velocity compared to its phosphonull counterpart, highlighting the modulatory role of M-domain phosphorylation on cMyBP-C function. Therefore, the nanosurfer assay provides a platform to precisely manipulate spatially dependent cMyBP-C binding partner interactions, shedding light on the molecular regulation of β-cardiac myosin contractility.
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Affiliation(s)
- Anja M Touma
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, MN, USA
| | - Wanjian Tang
- Department of Cellular and Molecular Physiology, Penn State College of Medicine, Hershey, Pennsylvania, USA
| | - David V Rasicci
- Department of Cellular and Molecular Physiology, Penn State College of Medicine, Hershey, Pennsylvania, USA
| | - Duha Vang
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, MN, USA
| | - Ashim Rai
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, MN, USA
| | - Samantha B Previs
- Department of Molecular Physiology and Biophysics, Cardiovascular Research Institute, University of Vermont, Burlington, VT
| | - David M Warshaw
- Department of Molecular Physiology and Biophysics, Cardiovascular Research Institute, University of Vermont, Burlington, VT
| | - Christopher M Yengo
- Department of Cellular and Molecular Physiology, Penn State College of Medicine, Hershey, Pennsylvania, USA
| | - Sivaraj Sivaramakrishnan
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, MN, USA.
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24
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Doh C, Dominic KL, Swanberg CE, Bharambe N, Willard BB, Li L, Ramachandran R, Stelzer JE. Identification of Phosphorylation and Other Post-Translational Modifications in the Central C4C5 Domains of Murine Cardiac Myosin Binding Protein C. ACS OMEGA 2022; 7:14189-14202. [PMID: 35573219 PMCID: PMC9089392 DOI: 10.1021/acsomega.2c00799] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Accepted: 04/05/2022] [Indexed: 05/06/2023]
Abstract
Cardiac myosin binding protein C (cMyBPC) is a critical multidomain protein that modulates myosin cross bridge behavior and cardiac contractility. cMyBPC is principally regulated by phosphorylation of the residues within the M-domain of its N-terminus. However, not much is known about the phosphorylation or other post-translational modification (PTM) landscape of the central C4C5 domains. In this study, the presence of phosphorylation outside the M-domain was confirmed in vivo using mouse models expressing cMyBPC with nonphosphorylatable serine (S) to alanine substitutions. Purified recombinant mouse C4C5 domain constructs were incubated with 13 different kinases, and samples from the 6 strongest kinases were chosen for mass spectrometry analysis. A total of 26 unique phosphorylated peptides were found, representing 13 different phosphorylation sites including 10 novel sites. Parallel reaction monitoring and subsequent mutagenesis experiments revealed that the S690 site (UniProtKB O70468) was the predominant target of PKA and PKG1. We also report 6 acetylation and 7 ubiquitination sites not previously described in the literature. These PTMs demonstrate the possibility of additional layers of regulation and potential importance of the central domains of cMyBPC in cardiac health and disease. Data are available via ProteomeXchange with identifier PXD031262.
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Affiliation(s)
- Chang
Yoon Doh
- Department
of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106, United States
| | - Katherine L. Dominic
- Department
of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106, United States
| | - Caitlin E. Swanberg
- Department
of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106, United States
| | - Nikhil Bharambe
- Department
of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106, United States
| | - Belinda B. Willard
- Proteomics
and Metabolomics Laboratory, Lerner Research Institute, The Cleveland Clinic Foundation, Cleveland, Ohio 44195, United States
| | - Ling Li
- Proteomics
and Metabolomics Laboratory, Lerner Research Institute, The Cleveland Clinic Foundation, Cleveland, Ohio 44195, United States
| | - Rajesh Ramachandran
- Department
of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106, United States
| | - Julian E. Stelzer
- Department
of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106, United States
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25
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Koubassova NA, Tsaturyan AK, Bershitsky SY, Ferenczi MA, Padrón R, Craig R. Interacting-heads motif explains the X-ray diffraction pattern of relaxed vertebrate skeletal muscle. Biophys J 2022; 121:1354-1366. [PMID: 35318005 PMCID: PMC9072692 DOI: 10.1016/j.bpj.2022.03.023] [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: 01/10/2022] [Revised: 01/25/2022] [Accepted: 03/17/2022] [Indexed: 11/19/2022] Open
Abstract
Electron microscopy (EM) shows that myosin heads in thick filaments isolated from striated muscles interact with each other and with the myosin tail under relaxing conditions. This "interacting-heads motif" (IHM) is highly conserved across the animal kingdom and is thought to be the basis of the super-relaxed state. However, a recent X-ray modeling study concludes, contrary to expectation, that the IHM is not present in relaxed intact muscle. We propose that this conclusion results from modeling with a thick filament 3D reconstruction in which the myosin heads have radially collapsed onto the thick filament backbone, not from absence of the IHM. Such radial collapse, by about 3-4 nm, is well established in EM studies of negatively stained myosin filaments, on which the reconstruction was based. We have tested this idea by carrying out similar X-ray modeling and determining the effect of the radial position of the heads on the goodness of fit to the X-ray pattern. We find that, when the IHM is modeled into a thick filament at a radius 3-4 nm greater than that modeled in the recent study, there is good agreement with the X-ray pattern. When the original (collapsed) radial position is used, the fit is poor, in agreement with that study. We show that modeling of the low-angle region of the X-ray pattern is relatively insensitive to the conformation of the myosin heads but very sensitive to their radial distance from the filament axis. We conclude that the IHM is sufficient to explain the X-ray diffraction pattern of intact muscle when placed at the appropriate radius.
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Affiliation(s)
| | | | - Sergey Y Bershitsky
- Institute of Immunology and Physiology, Russian Academy of Sciences, Yekaterinburg, Russia
| | - Michael A Ferenczi
- Brunel Medical School, College of Health, Medicine and Life Sciences, Brunel University London, Uxbridge, UK
| | - Raúl Padrón
- Division of Cell Biology and Imaging, Department of Radiology, University of Massachusetts Chan Medical School, Worcester, Massachusetts
| | - Roger Craig
- Division of Cell Biology and Imaging, Department of Radiology, University of Massachusetts Chan Medical School, Worcester, Massachusetts.
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26
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Small Angle X-ray Diffraction as a Tool for Structural Characterization of Muscle Disease. Int J Mol Sci 2022; 23:ijms23063052. [PMID: 35328477 PMCID: PMC8949570 DOI: 10.3390/ijms23063052] [Citation(s) in RCA: 32] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Revised: 03/01/2022] [Accepted: 03/02/2022] [Indexed: 02/01/2023] Open
Abstract
Small angle X-ray fiber diffraction is the method of choice for obtaining molecular level structural information from striated muscle fibers under hydrated physiological conditions. For many decades this technique had been used primarily for investigating basic biophysical questions regarding muscle contraction and regulation and its use confined to a relatively small group of expert practitioners. Over the last 20 years, however, X-ray diffraction has emerged as an important tool for investigating the structural consequences of cardiac and skeletal myopathies. In this review we show how simple and straightforward measurements, accessible to non-experts, can be used to extract biophysical parameters that can help explain and characterize the physiology and pathology of a given experimental system. We provide a comprehensive guide to the range of the kinds of measurements that can be made and illustrate how they have been used to provide insights into the structural basis of pathology in a comprehensive review of the literature. We also show how these kinds of measurements can inform current controversies and indicate some future directions.
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27
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Suay-Corredera C, Alegre-Cebollada J. The mechanics of the heart: zooming in on hypertrophic cardiomyopathy and cMyBP-C. FEBS Lett 2022; 596:703-746. [PMID: 35224729 DOI: 10.1002/1873-3468.14301] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Revised: 01/10/2022] [Accepted: 01/14/2022] [Indexed: 11/10/2022]
Abstract
Hypertrophic cardiomyopathy (HCM), a disease characterized by cardiac muscle hypertrophy and hypercontractility, is the most frequently inherited disorder of the heart. HCM is mainly caused by variants in genes encoding proteins of the sarcomere, the basic contractile unit of cardiomyocytes. The most frequently mutated among them is MYBPC3, which encodes cardiac myosin-binding protein C (cMyBP-C), a key regulator of sarcomere contraction. In this review, we summarize clinical and genetic aspects of HCM and provide updated information on the function of the healthy and HCM sarcomere, as well as on emerging therapeutic options targeting sarcomere mechanical activity. Building on what is known about cMyBP-C activity, we examine different pathogenicity drivers by which MYBPC3 variants can cause disease, focussing on protein haploinsufficiency as a common pathomechanism also in nontruncating variants. Finally, we discuss recent evidence correlating altered cMyBP-C mechanical properties with HCM development.
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28
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Sun S, Karki C, Gao BZ, Li L. Molecular mechanisms of cardiac actomyosin transforming from rigor state to post-rigor state. J Chem Phys 2022; 156:035101. [PMID: 35065578 PMCID: PMC9305598 DOI: 10.1063/5.0078166] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Sudden cardiac death contributed to half of all deaths from cardiovascular diseases. The mechanism of the kinetic cycle of cardiac myosin is crucial for heart protection and drug development. The state change in the myosin kinetic cycle from the rigor state to the post-rigor state is fundamental to explain binding and dissociation. Here, we used β-cardiac myosin in the rigor and post-rigor states to model the actomyosin complexes. Molecular dynamics simulations, electrostatic analysis, and energetic analysis of actomyosin complexes were performed in this work. The results showed that there are fewer interactions and lower electrostatic binding strength in the post-rigor state than in the rigor state. In the post-rigor state, there were higher free binding energy, fewer salt bridges, and fewer hydrogen bonds. The results showed a lower binding affinity in the post-rigor state than in the rigor state. The decrease in the binding affinity provided important conditions for dissociation of the myosin from the actin filament. Although previous studies focused mostly on the binding process, this study provides evidence of dissociation, which is even more important in the myosin kinetic cycle. This research on the mechanism of myosin kinetic cycles provides a novel direction for future genetic disease studies.
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Affiliation(s)
- Shengjie Sun
- Computational Science Program, The University of Texas at El Paso, 500 W University Ave., El Paso, Texas 79968, USA
| | - Chitra Karki
- Computational Science Program, The University of Texas at El Paso, 500 W University Ave., El Paso, Texas 79968, USA
| | - Bruce Z. Gao
- Department of Bioengineering, Clemson University, Clemson, South Carolina 29634, USA
| | - Lin Li
- Author to whom correspondence should be addressed:
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29
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Actomyosin Complex. Subcell Biochem 2022; 99:421-470. [PMID: 36151385 PMCID: PMC9710302 DOI: 10.1007/978-3-031-00793-4_14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Formation of cross-bridges between actin and myosin occurs ubiquitously in eukaryotic cells and mediates muscle contraction, intracellular cargo transport, and cytoskeletal remodeling. Myosin motors repeatedly bind to and dissociate from actin filaments in a cycle that transduces the chemical energy from ATP hydrolysis into mechanical force generation. While the general layout of surface elements within the actin-binding interface is conserved among myosin classes, sequence divergence within these motifs alters the specific contacts involved in the actomyosin interaction as well as the kinetics of mechanochemical cycle phases. Additionally, diverse lever arm structures influence the motility and force production of myosin molecules during their actin interactions. The structural differences generated by myosin's molecular evolution have fine-tuned the kinetics of its isoforms and adapted them for their individual cellular roles. In this chapter, we will characterize the structural and biochemical basis of the actin-myosin interaction and explain its relationship with myosin's cellular roles, with emphasis on the structural variation among myosin isoforms that enables their functional specialization. We will also discuss the impact of accessory proteins, such as the troponin-tropomyosin complex and myosin-binding protein C, on the formation and regulation of actomyosin cross-bridges.
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30
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Burghardt TP. Natural variant frequencies across domains from different sarcomere proteins cross-correlate to identify inter-protein contacts associated with cardiac muscle function and disease. MOLECULAR BIOMEDICINE 2021; 2:35. [PMID: 35006463 PMCID: PMC8607394 DOI: 10.1186/s43556-021-00056-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Accepted: 09/23/2021] [Indexed: 12/15/2022] Open
Abstract
Coordinated sarcomere proteins produce contraction force for muscle shortening. In human ventriculum they include the cardiac myosin motor (βmys), repetitively converting ATP free energy into work, and myosin binding protein C (MYBPC3) that in complex with βmys is regulatory. Single nucleotide variants (SNVs) causing hereditary heart diseases frequently target this protein pair. The βmys/MYBPC3 complex models a regulated motor and is used here to study how the proteins couple. SNVs in βmys or MYBPC3 survey human populations worldwide. Their protein expression modifies domain structure affecting phenotype and pathogenicity outcomes. When the SNV modified domain locates to inter-protein contacts it could affect complex coordination. Domains involved, one in βmys the other in MYBPC3, form coordinated domains (co-domains). Co-domain bilateral structure implies the possibility for a shared impact from SNV modification in either domain suggesting a correlated response to a common perturbation could identify their location. Genetic divergence over human populations is proposed to perturb SNV probability coupling that is detected by cross-correlation in 2D correlation genetics (2D-CG). SNV probability data and 2D-CG identify three critical sites, two in MYBPC3 with links to several domains across the βmys motor, and, one in βmys with links to the MYBPC3 regulatory domain. MYBPC3 sites are hinges sterically enabling regulatory interactions with βmys. The βmys site is the actin binding C-loop (residues 359-377). The C-loop is a trigger for actin-activated myosin ATPase and a contraction velocity modulator. Co-domain identification implies their spatial proximity suggesting a novel approach for in vivo protein complex structure determination.
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Affiliation(s)
- Thomas P Burghardt
- Department of Biochemistry and Molecular Biology, Mayo Clinic Rochester, 200 First St. SW, Rochester, MN, 55905, USA.
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31
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Schwäbe FV, Peter EK, Taft MH, Manstein DJ. Assessment of the Contribution of a Thermodynamic and Mechanical Destabilization of Myosin-Binding Protein C Domain C2 to the Pathomechanism of Hypertrophic Cardiomyopathy-Causing Double Mutation MYBPC3Δ25bp/D389V. Int J Mol Sci 2021; 22:ijms222111949. [PMID: 34769381 PMCID: PMC8584774 DOI: 10.3390/ijms222111949] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Revised: 10/31/2021] [Accepted: 11/02/2021] [Indexed: 01/01/2023] Open
Abstract
Mutations in the gene encoding cardiac myosin-binding protein-C (MyBPC), a thick filament assembly protein that stabilizes sarcomeric structure and regulates cardiac function, are a common cause for the development of hypertrophic cardiomyopathy. About 10% of carriers of the Δ25bp variant of MYBPC3, which is common in individuals from South Asia, are also carriers of the D389V variant on the same allele. Compared with noncarriers and those with MYBPC3Δ25bp alone, indicators for the development of hypertrophic cardiomyopathy occur with increased frequency in MYBPC3Δ25bp/D389V carriers. Residue D389 lies in the IgI-like C2 domain that is part of the N-terminal region of MyBPC. To probe the effects of mutation D389V on structure, thermostability, and protein–protein interactions, we produced and characterized wild-type and mutant constructs corresponding to the isolated 10 kDa C2 domain and a 52 kDa N-terminal fragment that includes subdomains C0 to C2. Our results show marked reductions in the melting temperatures of D389V mutant constructs. Interactions of construct C0–C2 D389V with the cardiac isoforms of myosin-2 and actin remain unchanged. Molecular dynamics simulations reveal changes in the stiffness and conformer dynamics of domain C2 caused by mutation D389V. Our results suggest a pathomechanism for the development of HCM based on the toxic buildup of misfolded protein in young MYBPC3Δ25bp/D389V carriers that is supplanted and enhanced by C-zone haploinsufficiency at older ages.
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Affiliation(s)
- Frederic V. Schwäbe
- Fritz Hartmann Centre for Medical Research, Institute for Biophysical Chemistry, Hannover Medical School, Carl Neuberg Str. 1, D-30625 Hannover, Germany; (F.V.S.); (E.K.P.); (M.H.T.)
| | - Emanuel K. Peter
- Fritz Hartmann Centre for Medical Research, Institute for Biophysical Chemistry, Hannover Medical School, Carl Neuberg Str. 1, D-30625 Hannover, Germany; (F.V.S.); (E.K.P.); (M.H.T.)
| | - Manuel H. Taft
- Fritz Hartmann Centre for Medical Research, Institute for Biophysical Chemistry, Hannover Medical School, Carl Neuberg Str. 1, D-30625 Hannover, Germany; (F.V.S.); (E.K.P.); (M.H.T.)
| | - Dietmar J. Manstein
- Fritz Hartmann Centre for Medical Research, Institute for Biophysical Chemistry, Hannover Medical School, Carl Neuberg Str. 1, D-30625 Hannover, Germany; (F.V.S.); (E.K.P.); (M.H.T.)
- Division for Structural Biochemistry, Hannover Medical School, Carl Neuberg Str. 1, D-30625 Hannover, Germany
- Correspondence:
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32
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Reconditi M, Brunello E, Fusi L, Linari M, Lombardi V, Irving M, Piazzesi G. Myosin motors that cannot bind actin leave their folded OFF state on activation of skeletal muscle. J Gen Physiol 2021; 153:212712. [PMID: 34668926 PMCID: PMC8532561 DOI: 10.1085/jgp.202112896] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The myosin motors in resting skeletal muscle are folded back against their tails in the thick filament in a conformation that makes them unavailable for binding to actin. When muscles are activated, calcium binding to troponin leads to a rapid change in the structure of the actin-containing thin filaments that uncovers the myosin binding sites on actin. Almost as quickly, myosin motors leave the folded state and move away from the surface of the thick filament. To test whether motor unfolding is triggered by the availability of nearby actin binding sites, we measured changes in the x-ray reflections that report motor conformation when muscles are activated at longer sarcomere length, so that part of the thick filaments no longer overlaps with thin filaments. We found that the intensity of the M3 reflection from the axial repeat of the motors along the thick filaments declines almost linearly with increasing sarcomere length up to 2.8 µm, as expected if motors in the nonoverlap zone had left the folded state and become relatively disordered. In a recent article in JGP, Squire and Knupp challenged this interpretation of the data. We show here that their analysis is based on an incorrect assumption about how the interference subpeaks of the M3 reflection were reported in our previous paper. We extend previous models of mass distribution along the filaments to show that the sarcomere length dependence of the M3 reflection is consistent with <10% of no-overlap motors remaining in the folded conformation during active contraction, confirming our previous conclusion that unfolding of myosin motors on muscle activation is not due to the availability of local actin binding sites.
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Affiliation(s)
- Massimo Reconditi
- PhysioLab, Università di Firenze, Sesto Fiorentino, Italy.,Consorzio Nazionale Interuniversitario per le Scienze Fisiche della Materia, Unità di Ricerca Università di Firenze, Florence, Italy
| | - Elisabetta Brunello
- Randall Centre for Cell and Molecular Biophysics, King's College London, London, UK
| | - Luca Fusi
- Randall Centre for Cell and Molecular Biophysics, King's College London, London, UK
| | - Marco Linari
- PhysioLab, Università di Firenze, Sesto Fiorentino, Italy
| | | | - Malcolm Irving
- Randall Centre for Cell and Molecular Biophysics, King's College London, London, UK
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33
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Risi CM, Patra M, Belknap B, Harris SP, White HD, Galkin VE. Interaction of the C2 Ig-like Domain of Cardiac Myosin Binding Protein-C with F-actin. J Mol Biol 2021; 433:167178. [PMID: 34329643 PMCID: PMC8453104 DOI: 10.1016/j.jmb.2021.167178] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Revised: 06/29/2021] [Accepted: 07/19/2021] [Indexed: 10/20/2022]
Abstract
Cardiac muscle contraction depends on interactions between thick (myosin) and thin (actin) filaments (TFs). TFs are regulated by intracellular Ca2+ levels. Under activating conditions Ca2+ binds to the troponin complex and displaces tropomyosin from myosin binding sites on the TF surface to allow actomyosin interactions. Recent studies have shown that in addition to Ca2+, the first four N-terminal domains (NTDs) of cardiac myosin binding protein C (cMyBP-C) (e.g. C0, C1, M and C2), are potent modulators of the TF activity, but the mechanism of their collective action is poorly understood. Previously, we showed that C1 activates the TF at low Ca2+ and C0 stabilizes binding of C1 to the TF, but the ability of C2 to bind and/or affect the TF remains unknown. Here we obtained 7.5 Å resolution cryo-EM reconstruction of C2-decorated actin filaments to demonstrate that C2 binds to actin in a single structural mode that does not activate the TF unlike the polymorphic binding of C0 and C1 to actin. Comparison of amino acid sequences of C2 with either C0 or C1 shows low levels of identity between the residues involved in interactions with the TF but high levels of conservation for residues involved in Ig fold stabilization. This provides a structural basis for strikingly different interactions of structurally homologous C0, C1 and C2 with the TF. Our detailed analysis of the interaction of C2 with the actin filament provides crucial information required to model the collective action of cMyBP-C NTDs on the cardiac TF.
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Affiliation(s)
- Cristina M Risi
- Department of Physiological Sciences, Eastern Virginia Medical School, Norfolk, VA 23507, USA
| | - Malay Patra
- Department of Physiological Sciences, Eastern Virginia Medical School, Norfolk, VA 23507, USA
| | - Betty Belknap
- Department of Physiological Sciences, Eastern Virginia Medical School, Norfolk, VA 23507, USA
| | - Samantha P Harris
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85724, USA
| | - Howard D White
- Department of Physiological Sciences, Eastern Virginia Medical School, Norfolk, VA 23507, USA
| | - Vitold E Galkin
- Department of Physiological Sciences, Eastern Virginia Medical School, Norfolk, VA 23507, USA.
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34
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Squire JM, Knupp C. Analysis methods and quality criteria for investigating muscle physiology using x-ray diffraction. J Gen Physiol 2021; 153:212538. [PMID: 34351359 PMCID: PMC8348228 DOI: 10.1085/jgp.202012778] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 12/23/2020] [Accepted: 07/12/2021] [Indexed: 12/20/2022] Open
Abstract
X-ray diffraction studies of muscle have been tremendously powerful in providing fundamental insights into the structures of, for example, the myosin and actin filaments in a variety of muscles and the physiology of the cross-bridge mechanism during the contractile cycle. However, interpretation of x-ray diffraction patterns is far from trivial, and if modeling of the observed diffraction intensities is required it needs to be performed carefully with full knowledge of the possible pitfalls. Here, we discuss (1) how x-ray diffraction can be used as a tool to monitor various specific muscle properties and (2) how to get the most out of the rest of the observed muscle x-ray diffraction patterns by modeling where the reliability of the modeling conclusions can be objectively tested. In other x-ray diffraction methods, such as protein crystallography, the reliability of every step of the process is estimated and quoted in published papers. In this way, the quality of the structure determination can be properly assessed. To be honest with ourselves in the muscle field, we need to do as near to the same as we can, within the limitations of the techniques that we are using. We discuss how this can be done. We also use test cases to reveal the dos and don’ts of using x-ray diffraction to study muscle physiology.
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Affiliation(s)
- John M Squire
- Muscle Contraction Group, School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, UK.,Faculty of Medicine, Imperial College, London, UK
| | - Carlo Knupp
- School of Optometry and Vision Sciences, Cardiff University, Cardiff, UK
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35
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Squire JM, Knupp C. The muscle M3 x-ray diffraction peak and sarcomere length: No evidence for disordered myosin heads out of actin overlap. J Gen Physiol 2021; 153:212534. [PMID: 34347004 PMCID: PMC8348229 DOI: 10.1085/jgp.202012859] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
X-ray diffraction studies of muscle have provided a wealth of information on muscle structure and physiology, and the meridian of the diffraction pattern is particularly informative. Reconditi et al. (2014. J. Physiol.https://doi.org/10.1113/jphysiol.2013.267849) performed superb experiments on changes to the M3 meridional peak as a function of sarcomere length (SL). They found that the M3 intensity dropped almost linearly as sarcomere length increased at least to about SL = 3.0 µm, and that it followed the same track as tension, pointing toward zero at the end of overlap at ∼3.6 µm. They concluded that, just as tension could only be generated by overlapped myosin heads, so ordered myosin heads contributing to the M3 intensity could only occur in the overlap region of the A-band, and that nonoverlapped heads must be highly disordered. Here we show that this conclusion is not consistent with x-ray diffraction theory; it would not explain their observations. We discuss one possible reason for the change in M3 intensity with increasing sarcomere length in terms of increasing axial misalignment of the myosin filaments that at longer sarcomere lengths is limited by the elastic stretching of the M-band and titin.
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Affiliation(s)
- John M Squire
- Muscle Contraction Group, School of Physiology, Pharmacology & Neuroscience, University of Bristol, Bristol, UK.,Faculty of Medicine, Imperial College London, London, UK
| | - Carlo Knupp
- School of Optometry and Vision Sciences, Cardiff University, Cardiff, UK
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36
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Kwon HK, Choi H, Park SG, Park WJ, Kim, DH, Park ZY. Integrated Quantitative Phosphoproteomics and Cell-based Functional Screening Reveals Specific Pathological Cardiac Hypertrophy-related Phosphorylation Sites. Mol Cells 2021; 44:500-516. [PMID: 34158421 PMCID: PMC8334354 DOI: 10.14348/molcells.2021.4002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2019] [Accepted: 01/07/2019] [Indexed: 12/29/2022] Open
Abstract
Cardiac hypertrophic signaling cascades resulting in heart failure diseases are mediated by protein phosphorylation. Recent developments in mass spectrometry-based phosphoproteomics have led to the identification of thousands of differentially phosphorylated proteins and their phosphorylation sites. However, functional studies of these differentially phosphorylated proteins have not been conducted in a large-scale or high-throughput manner due to a lack of methods capable of revealing the functional relevance of each phosphorylation site. In this study, an integrated approach combining quantitative phosphoproteomics and cell-based functional screening using phosphorylation competition peptides was developed. A pathological cardiac hypertrophy model, junctate-1 transgenic mice and control mice, were analyzed using label-free quantitative phosphoproteomics to identify differentially phosphorylated proteins and sites. A cell-based functional assay system measuring hypertrophic cell growth of neonatal rat ventricle cardiomyocytes (NRVMs) following phenylephrine treatment was applied, and changes in phosphorylation of individual differentially phosphorylated sites were induced by incorporation of phosphorylation competition peptides conjugated with cell-penetrating peptides. Cell-based functional screening against 18 selected phosphorylation sites identified three phosphorylation sites (Ser-98, Ser-179 of Ldb3, and Ser-1146 of palladin) displaying near-complete inhibition of cardiac hypertrophic growth of NRVMs. Changes in phosphorylation levels of Ser-98 and Ser-179 in Ldb3 were further confirmed in NRVMs and other pathological/physiological hypertrophy models, including transverse aortic constriction and swimming models, using site-specific phospho-antibodies. Our integrated approach can be used to identify functionally important phosphorylation sites among differentially phosphorylated sites, and unlike conventional approaches, it is easily applicable for large-scale and/or high-throughput analyses.
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Affiliation(s)
- Hye Kyeong Kwon
- School of Life Sciences, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, Korea
| | - Hyunwoo Choi
- School of Life Sciences, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, Korea
| | - Sung-Gyoo Park
- School of Life Sciences, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, Korea
| | - Woo Jin Park
- School of Life Sciences, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, Korea
| | - Do Han Kim,
- School of Life Sciences, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, Korea
| | - Zee-Yong Park
- School of Life Sciences, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, Korea
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37
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Lynch TL, Kumar M, McNamara JW, Kuster DWD, Sivaguru M, Singh RR, Previs MJ, Lee KH, Kuffel G, Zilliox MJ, Lin BL, Ma W, Gibson AM, Blaxall BC, Nieman ML, Lorenz JN, Leichter DM, Leary OP, Janssen PML, de Tombe PP, Gilbert RJ, Craig R, Irving T, Warshaw DM, Sadayappan S. Amino terminus of cardiac myosin binding protein-C regulates cardiac contractility. J Mol Cell Cardiol 2021; 156:33-44. [PMID: 33781820 PMCID: PMC8217138 DOI: 10.1016/j.yjmcc.2021.03.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Revised: 03/21/2021] [Accepted: 03/22/2021] [Indexed: 12/12/2022]
Abstract
Phosphorylation of cardiac myosin binding protein-C (cMyBP-C) regulates cardiac contraction through modulation of actomyosin interactions mediated by the protein's amino terminal (N')-region (C0-C2 domains, 358 amino acids). On the other hand, dephosphorylation of cMyBP-C during myocardial injury results in cleavage of the 271 amino acid C0-C1f region and subsequent contractile dysfunction. Yet, our current understanding of amino terminus region of cMyBP-C in the context of regulating thin and thick filament interactions is limited. A novel cardiac-specific transgenic mouse model expressing cMyBP-C, but lacking its C0-C1f region (cMyBP-C∆C0-C1f), displayed dilated cardiomyopathy, underscoring the importance of the N'-region in cMyBP-C. Further exploring the molecular basis for this cardiomyopathy, in vitro studies revealed increased interfilament lattice spacing and rate of tension redevelopment, as well as faster actin-filament sliding velocity within the C-zone of the transgenic sarcomere. Moreover, phosphorylation of the unablated phosphoregulatory sites was increased, likely contributing to normal sarcomere morphology and myoarchitecture. These results led us to hypothesize that restoration of the N'-region of cMyBP-C would return actomyosin interaction to its steady state. Accordingly, we administered recombinant C0-C2 (rC0-C2) to permeabilized cardiomyocytes from transgenic, cMyBP-C null, and human heart failure biopsies, and we found that normal regulation of actomyosin interaction and contractility was restored. Overall, these data provide a unique picture of selective perturbations of the cardiac sarcomere that either lead to injury or adaptation to injury in the myocardium.
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Affiliation(s)
- Thomas L Lynch
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, IL 60153, USA
| | - Mohit Kumar
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, IL 60153, USA; Heart, Lung and Vascular Institute, Division of Cardiovascular Health and Disease, Department of Internal Medicine, University of Cincinnati, Cincinnati, OH 45267, USA
| | - James W McNamara
- Heart, Lung and Vascular Institute, Division of Cardiovascular Health and Disease, Department of Internal Medicine, University of Cincinnati, Cincinnati, OH 45267, USA
| | - Diederik W D Kuster
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, IL 60153, USA; Department of Physiology, Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam Cardiovascular Sciences, Amsterdam, the Netherlands
| | - Mayandi Sivaguru
- Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Rohit R Singh
- Heart, Lung and Vascular Institute, Division of Cardiovascular Health and Disease, Department of Internal Medicine, University of Cincinnati, Cincinnati, OH 45267, USA
| | - Michael J Previs
- Department of Molecular Physiology and Biophysics, Cardiovascular Research Institute, University of Vermont, Burlington, VT 05405, USA
| | - Kyoung Hwan Lee
- Division of Cell Biology and Imaging, Department of Radiology, University of Massachusetts Medical School, Worcester, MA 01655, USA
| | - Gina Kuffel
- Department of Public Health Sciences, Loyola University Chicago, Maywood, IL 60153, USA
| | - Michael J Zilliox
- Department of Public Health Sciences, Loyola University Chicago, Maywood, IL 60153, USA
| | - Brian Leei Lin
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, IL 60153, USA
| | - Weikang Ma
- Center for Synchrotron Radiation Research and Instrumentation and Department of Biological Sciences, Illinois Institute of Technology, Chicago, IL 60616, USA
| | - Aaron M Gibson
- Department of Pediatrics, Heart Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, USA
| | - Burns C Blaxall
- Department of Pediatrics, Heart Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, USA
| | - Michelle L Nieman
- Department of Pharmacology and Systems Physiology, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - John N Lorenz
- Department of Pharmacology and Systems Physiology, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Dana M Leichter
- Research Service, Providence VA Medical Center, Providence, RI 02908, USA
| | - Owen P Leary
- Research Service, Providence VA Medical Center, Providence, RI 02908, USA
| | - Paul M L Janssen
- Department of Physiology and Cell Biology, The Ohio State University, Columbus, OH 43210, USA
| | - Pieter P de Tombe
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, IL 60153, USA; Department of Physiology, University of Illinois at Chicago, Chicago 60612, USA; Phymedexp, Université de Montpellier, Inserm, CNRS, Montpellier, France
| | - Richard J Gilbert
- Research Service, Providence VA Medical Center, Providence, RI 02908, USA
| | - Roger Craig
- Division of Cell Biology and Imaging, Department of Radiology, University of Massachusetts Medical School, Worcester, MA 01655, USA
| | - Thomas Irving
- Center for Synchrotron Radiation Research and Instrumentation and Department of Biological Sciences, Illinois Institute of Technology, Chicago, IL 60616, USA
| | - David M Warshaw
- Department of Molecular Physiology and Biophysics, Cardiovascular Research Institute, University of Vermont, Burlington, VT 05405, USA
| | - Sakthivel Sadayappan
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, IL 60153, USA; Heart, Lung and Vascular Institute, Division of Cardiovascular Health and Disease, Department of Internal Medicine, University of Cincinnati, Cincinnati, OH 45267, USA.
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38
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Suay-Corredera C, Pricolo MR, Velázquez-Carreras D, Pathak D, Nandwani N, Pimenta-Lopes C, Sánchez-Ortiz D, Urrutia-Irazabal I, Vilches S, Dominguez F, Frisso G, Monserrat L, García-Pavía P, de Sancho D, Spudich JA, Ruppel KM, Herrero-Galán E, Alegre-Cebollada J. Nanomechanical Phenotypes in Cardiac Myosin-Binding Protein C Mutants That Cause Hypertrophic Cardiomyopathy. ACS NANO 2021; 15:10203-10216. [PMID: 34060810 PMCID: PMC8514129 DOI: 10.1021/acsnano.1c02242] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Hypertrophic cardiomyopathy (HCM) is a disease of the myocardium caused by mutations in sarcomeric proteins with mechanical roles, such as the molecular motor myosin. Around half of the HCM-causing genetic variants target contraction modulator cardiac myosin-binding protein C (cMyBP-C), although the underlying pathogenic mechanisms remain unclear since many of these mutations cause no alterations in protein structure and stability. As an alternative pathomechanism, here we have examined whether pathogenic mutations perturb the nanomechanics of cMyBP-C, which would compromise its modulatory mechanical tethers across sliding actomyosin filaments. Using single-molecule atomic force spectroscopy, we have quantified mechanical folding and unfolding transitions in cMyBP-C domains targeted by HCM mutations that do not induce RNA splicing alterations or protein thermodynamic destabilization. Our results show that domains containing mutation R495W are mechanically weaker than wild-type at forces below 40 pN and that R502Q mutant domains fold faster than wild-type. None of these alterations are found in control, nonpathogenic variants, suggesting that nanomechanical phenotypes induced by pathogenic cMyBP-C mutations contribute to HCM development. We propose that mutation-induced nanomechanical alterations may be common in mechanical proteins involved in human pathologies.
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Affiliation(s)
| | - Maria Rosaria Pricolo
- Centro Nacional de Investigaciones Cardiovasculares (CNIC), 28029, Madrid, Spain
- Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Università di Napoli Federico II, 80131, Naples, Italy
| | | | - Divya Pathak
- Department of Biochemistry, Stanford University School of Medicine, Stanford, California 94305, United States
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, California 94305, United States
| | - Neha Nandwani
- Department of Biochemistry, Stanford University School of Medicine, Stanford, California 94305, United States
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, California 94305, United States
| | | | - David Sánchez-Ortiz
- Centro Nacional de Investigaciones Cardiovasculares (CNIC), 28029, Madrid, Spain
| | | | - Silvia Vilches
- Heart Failure and Inherited Cardiac Diseases Unit, Department of Cardiology, Hospital Universitario Puerta de Hierro, 28222, Madrid, Spain
- European Reference Network for Rare and Low Prevalence Complex Diseases of the Heart (ERN GUARD-HEART, http://guardheart.ern-net.eu/), 28222, Madrid, Spain
| | - Fernando Dominguez
- Centro Nacional de Investigaciones Cardiovasculares (CNIC), 28029, Madrid, Spain
- Heart Failure and Inherited Cardiac Diseases Unit, Department of Cardiology, Hospital Universitario Puerta de Hierro, 28222, Madrid, Spain
- European Reference Network for Rare and Low Prevalence Complex Diseases of the Heart (ERN GUARD-HEART, http://guardheart.ern-net.eu/), 28222, Madrid, Spain
- Centro de Investigación Biomédica en Red en Enfermedades Cardiovasculares (CIBERCV), 28029, Madrid, Spain
| | - Giulia Frisso
- Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Università di Napoli Federico II, 80131, Naples, Italy
- CEINGE Biotecnologie Avanzate, scarl, 80145, Naples, Italy
| | | | - Pablo García-Pavía
- Heart Failure and Inherited Cardiac Diseases Unit, Department of Cardiology, Hospital Universitario Puerta de Hierro, 28222, Madrid, Spain
- European Reference Network for Rare and Low Prevalence Complex Diseases of the Heart (ERN GUARD-HEART, http://guardheart.ern-net.eu/), 28222, Madrid, Spain
- Centro de Investigación Biomédica en Red en Enfermedades Cardiovasculares (CIBERCV), 28029, Madrid, Spain
- Universidad Francisco de Vitoria (UFV), 28223, Pozuelo de Alarcón, Madrid, Spain
| | - David de Sancho
- Polimero eta Material Aurreratuak: Fisika, Kimika eta Teknologia, Kimika Fakultatea, Euskal Herriko Unibertsitatea UPV/EHU, 20018, Donostia-San Sebastián, Spain
- Donostia International Physics Center (DIPC), 20018, Donostia-San Sebastián, Spain
| | - James A Spudich
- Department of Biochemistry, Stanford University School of Medicine, Stanford, California 94305, United States
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, California 94305, United States
| | - Kathleen M Ruppel
- Department of Biochemistry, Stanford University School of Medicine, Stanford, California 94305, United States
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, California 94305, United States
| | - Elías Herrero-Galán
- Centro Nacional de Investigaciones Cardiovasculares (CNIC), 28029, Madrid, Spain
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39
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Jang SH, Lee J, Lee O. Micro- and nano-tomography analysis of mouse soleus muscle using radiation. Microsc Res Tech 2021; 84:2685-2693. [PMID: 34021519 DOI: 10.1002/jemt.23819] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2021] [Revised: 04/13/2021] [Accepted: 05/02/2021] [Indexed: 11/10/2022]
Abstract
In this study, we analyze radiation images of muscle structure of mice soleus muscles using radiation source-based microtomography and nanotomography. Soleus muscle samples were collected for analysis from 8-week-old male Institute of Cancer Research mice. First, phase-contrast X-ray microtomography was employed in these experiments. Then to obtain images with excellent contrast, imaging was performed using monochromatic light with excellent transmission power. To analyze additional muscle structures in higher magnification images than these images, nanotomography was performed, which facilitated obtaining high-magnification and high-resolution images. Muscle tissue microstructures were confirmed through three-dimensional images obtained from phase-contrast X-ray microtomography. Thus, the muscle tissue's overall shape at microscopic level can be captured. Additionally, a single muscle fiber was examined using hard X-ray nano-imaging, through which we could observe the alignment of countless myofibrils, that is, actin and myosin filaments in the muscle fibers. Thus, the methodology adopted here proved to be advantageous in analyzing the muscle tissue's overall structure with microtomography and in observing the myofibrils in detail using nanotomography.
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Affiliation(s)
- Sang-Hun Jang
- Department of Physical Therapy, College of Health and Life Science, Korea National University of Transportation, Jeungpyeong-eup, Chungbuk, Republic of Korea
| | - Jiwon Lee
- Department of Software Convergence, Graduate School, Soonchunhyang University, Asan City, Chungnam, Republic of Korea
| | - Onseok Lee
- Department of Software Convergence, Graduate School, Soonchunhyang University, Asan City, Chungnam, Republic of Korea.,Department of Medical IT Engineering, College of Medical Sciences, Soonchunhyang University, Asan City, Chungnam, Republic of Korea
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40
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Wang Z, Grange M, Wagner T, Kho AL, Gautel M, Raunser S. The molecular basis for sarcomere organization in vertebrate skeletal muscle. Cell 2021; 184:2135-2150.e13. [PMID: 33765442 PMCID: PMC8054911 DOI: 10.1016/j.cell.2021.02.047] [Citation(s) in RCA: 80] [Impact Index Per Article: 26.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Revised: 01/27/2021] [Accepted: 02/22/2021] [Indexed: 12/20/2022]
Abstract
Sarcomeres are force-generating and load-bearing devices of muscles. A precise molecular picture of how sarcomeres are built underpins understanding their role in health and disease. Here, we determine the molecular architecture of native vertebrate skeletal sarcomeres by electron cryo-tomography. Our reconstruction reveals molecular details of the three-dimensional organization and interaction of actin and myosin in the A-band, I-band, and Z-disc and demonstrates that α-actinin cross-links antiparallel actin filaments by forming doublets with 6-nm spacing. Structures of myosin, tropomyosin, and actin at ~10 Å further reveal two conformations of the "double-head" myosin, where the flexible orientation of the lever arm and light chains enable myosin not only to interact with the same actin filament, but also to split between two actin filaments. Our results provide unexpected insights into the fundamental organization of vertebrate skeletal muscle and serve as a strong foundation for future investigations of muscle diseases.
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Affiliation(s)
- Zhexin Wang
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Otto-Hahn-Strasse 11, 44227 Dortmund, Germany
| | - Michael Grange
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Otto-Hahn-Strasse 11, 44227 Dortmund, Germany
| | - Thorsten Wagner
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Otto-Hahn-Strasse 11, 44227 Dortmund, Germany
| | - Ay Lin Kho
- The Randall Centre for Cell and Molecular Biophysics, School of Basic and Medical Biosciences, Kings College London BHF Excellence Centre, New Hunt's House, Guy's Campus, London SE1 1UL, UK
| | - Mathias Gautel
- The Randall Centre for Cell and Molecular Biophysics, School of Basic and Medical Biosciences, Kings College London BHF Excellence Centre, New Hunt's House, Guy's Campus, London SE1 1UL, UK
| | - Stefan Raunser
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Otto-Hahn-Strasse 11, 44227 Dortmund, Germany.
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41
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Fazlollahi F, Santini Gonzalez JJ, Repas SJ, Canan BD, Billman GE, Janssen PML. Contraction-relaxation coupling is unaltered by exercise training and infarction in isolated canine myocardium. J Gen Physiol 2021; 153:211978. [PMID: 33847735 PMCID: PMC8047736 DOI: 10.1085/jgp.202012829] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Revised: 02/20/2021] [Accepted: 03/18/2021] [Indexed: 12/28/2022] Open
Abstract
The two main phases of the mammalian cardiac cycle are contraction and relaxation; however, whether there is a connection between them in humans is not well understood. Routine exercise has been shown to improve cardiac function, morphology, and molecular signatures. Likewise, the acute and chronic changes that occur in the heart in response to injury, disease, and stress are well characterized, albeit not fully understood. In this study, we investigated how exercise and myocardial injury affect contraction–relaxation coupling. We retrospectively analyzed the correlation between the maximal speed of contraction and the maximal speed of relaxation of canine myocardium after receiving surgically induced myocardial infarction, followed by either sedentary recovery or exercise training for 10–12 wk. We used isolated right ventricular trabeculae, which were electrically paced at different lengths, frequencies, and with increasing β-adrenoceptor stimulation. In all conditions, contraction and relaxation were linearly correlated, irrespective of injury or training history. Based on these results and the available literature, we posit that contraction–relaxation coupling is a fundamental myocardial property that resides in the structural arrangement of proteins at the level of the sarcomere and that this may be regulated by the actions of cardiac myosin binding protein C (cMyBP-C) on actin and myosin.
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Affiliation(s)
- Farbod Fazlollahi
- Department of Physiology and Cell Biology, College of Medicine, Ohio State University, Columbus, OH
| | - Jorge J Santini Gonzalez
- Department of Physiology and Cell Biology, College of Medicine, Ohio State University, Columbus, OH
| | - Steven J Repas
- Department of Physiology and Cell Biology, College of Medicine, Ohio State University, Columbus, OH
| | - Benjamin D Canan
- Department of Physiology and Cell Biology, College of Medicine, Ohio State University, Columbus, OH
| | - George E Billman
- Department of Physiology and Cell Biology, College of Medicine, Ohio State University, Columbus, OH
| | - Paul M L Janssen
- Department of Physiology and Cell Biology, College of Medicine, Ohio State University, Columbus, OH
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42
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Rahmanseresht S, Lee KH, O’Leary TS, McNamara JW, Sadayappan S, Robbins J, Warshaw DM, Craig R, Previs MJ. The N terminus of myosin-binding protein C extends toward actin filaments in intact cardiac muscle. J Gen Physiol 2021; 153:e202012726. [PMID: 33528507 PMCID: PMC7852460 DOI: 10.1085/jgp.202012726] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Revised: 10/23/2020] [Accepted: 12/03/2020] [Indexed: 12/31/2022] Open
Abstract
Myosin and actin filaments are highly organized within muscle sarcomeres. Myosin-binding protein C (MyBP-C) is a flexible, rod-like protein located within the C-zone of the sarcomere. The C-terminal domain of MyBP-C is tethered to the myosin filament backbone, and the N-terminal domains are postulated to interact with actin and/or the myosin head to modulate filament sliding. To define where the N-terminal domains of MyBP-C are localized in the sarcomere of active and relaxed mouse myocardium, the relative positions of the N terminus of MyBP-C and actin were imaged in fixed muscle samples using super-resolution fluorescence microscopy. The resolution of the imaging was enhanced by particle averaging. The images demonstrate that the position of the N terminus of MyBP-C is biased toward the actin filaments in both active and relaxed muscle preparations. Comparison of the experimental images with images generated in silico, accounting for known binding partner interactions, suggests that the N-terminal domains of MyBP-C may bind to actin and possibly the myosin head but only when the myosin head is in the proximity of an actin filament. These physiologically relevant images help define the molecular mechanism by which the N-terminal domains of MyBP-C may search for, and capture, molecular binding partners to tune cardiac contractility.
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Affiliation(s)
- Sheema Rahmanseresht
- Department of Molecular Physiology and Biophysics, Cardiovascular Research Institute, University of Vermont, Burlington, VT
| | - Kyoung H. Lee
- Division of Cell Biology and Imaging, Department of Radiology, University of Massachusetts Medical School, Worcester, MA
| | - Thomas S. O’Leary
- Department of Molecular Physiology and Biophysics, Cardiovascular Research Institute, University of Vermont, Burlington, VT
| | - James W. McNamara
- Heart, Lung and Vascular Institute, Department of Internal Medicine, Division of Cardiovascular Health and Disease, University of Cincinnati, Cincinnati, OH
| | - Sakthivel Sadayappan
- Heart, Lung and Vascular Institute, Department of Internal Medicine, Division of Cardiovascular Health and Disease, University of Cincinnati, Cincinnati, OH
| | - Jeffrey Robbins
- Department of Pediatrics and the Heart Institute, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH
| | - David M. Warshaw
- Department of Molecular Physiology and Biophysics, Cardiovascular Research Institute, University of Vermont, Burlington, VT
| | - Roger Craig
- Division of Cell Biology and Imaging, Department of Radiology, University of Massachusetts Medical School, Worcester, MA
| | - Michael J. Previs
- Department of Molecular Physiology and Biophysics, Cardiovascular Research Institute, University of Vermont, Burlington, VT
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43
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Colson BA. In the eye of the STORM: Tracking the myosin-binding protein C N terminus in heart muscle. J Gen Physiol 2021; 153:211776. [PMID: 33566085 PMCID: PMC7879487 DOI: 10.1085/jgp.202012830] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Colson discusses a recent investigation of the localization of N-terminal myosin-binding protein C in cardiac muscle.
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Affiliation(s)
- Brett A Colson
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ
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44
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Schmid M, Toepfer CN. Cardiac myosin super relaxation (SRX): a perspective on fundamental biology, human disease and therapeutics. Biol Open 2021; 10:10/2/bio057646. [PMID: 33589442 PMCID: PMC7904003 DOI: 10.1242/bio.057646] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The fundamental basis of muscle contraction 'the sliding filament model' (Huxley and Niedergerke, 1954; Huxley and Hanson, 1954) and the 'swinging, tilting crossbridge-sliding filament mechanism' (Huxley, 1969; Huxley and Brown, 1967) nucleated a field of research that has unearthed the complex and fascinating role of myosin structure in the regulation of contraction. A recently discovered energy conserving state of myosin termed the super relaxed state (SRX) has been observed in filamentous myosins and is central to modulating force production and energy use within the sarcomere. Modulation of myosin function through SRX is a rapidly developing theme in therapeutic development for both cardiovascular disease and infectious disease. Some 70 years after the first discoveries concerning muscular function, modulation of myosin SRX may bring the first myosin targeted small molecule to the clinic, for treating hypertrophic cardiomyopathy (Olivotto et al., 2020). An often monogenic disease HCM afflicts 1 in 500 individuals, and can cause heart failure and sudden cardiac death. Even as we near therapeutic translation, there remain many questions about the governance of muscle function in human health and disease. With this review, we provide a broad overview of contemporary understanding of myosin SRX, and explore the complexities of targeting this myosin state in human disease.This article has an associated Future Leaders to Watch interview with the authors of the paper.
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Affiliation(s)
- Manuel Schmid
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford OX3 9DU, UK
| | - Christopher N Toepfer
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford OX3 9DU, UK
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
- Wellcome Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
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45
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Sun S, Karki C, Xie Y, Xian Y, Guo W, Gao BZ, Li L. Hybrid method for representing ions in implicit solvation calculations. Comput Struct Biotechnol J 2021; 19:801-811. [PMID: 33598096 PMCID: PMC7847951 DOI: 10.1016/j.csbj.2021.01.020] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Revised: 01/09/2021] [Accepted: 01/14/2021] [Indexed: 12/16/2022] Open
Abstract
Fast and accurate calculations of the electrostatic features of highly charged biomolecules such as DNA, RNA, and highly charged proteins are crucial and challenging tasks. Traditional implicit solvent methods calculate the electrostatic features quickly, but these methods are not able to balance the high net biomolecular charges effectively. Explicit solvent methods add unbalanced ions to neutralize the highly charged biomolecules in molecular dynamic simulations, which require more expensive computing resources. Here we report developing a novel method, Hybridizing Ions Treatment (HIT), which hybridizes the implicit solvent method with an explicit method to realistically calculate the electrostatic potential for highly charged biomolecules. HIT utilizes the ionic distribution from an explicit method to predict the bound ions. The bound ions are then added in the implicit solvent method to perform the electrostatic potential calculations. In this study, two training sets were developed to optimize parameters for HIT. The performance on the testing set demonstrates that HIT significantly improves the electrostatic calculations. Results on molecular motors myosin and kinesin reveal some mechanisms and explain some previous experimental findings. HIT can be widely used to study highly charged biomolecules, including DNA, RNA, molecular motors, and other highly charged biomolecules. The HIT package is available at http://compbio.utep.edu/static/downloads/download_hit.zip.
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Affiliation(s)
- Shengjie Sun
- Computational Science Program, University of Texas at El Paso, 500 W University Ave, TX 79968, USA
| | - Chitra Karki
- Computational Science Program, University of Texas at El Paso, 500 W University Ave, TX 79968, USA
| | - Yixin Xie
- Computational Science Program, University of Texas at El Paso, 500 W University Ave, TX 79968, USA
| | - Yuejiao Xian
- Department of Chemistry, University of Texas at El Paso, 500 W University Ave, TX 79968, USA
| | - Wenhan Guo
- Computational Science Program, University of Texas at El Paso, 500 W University Ave, TX 79968, USA
| | - Bruce Z Gao
- Department of Bioengineering, Clemson University, Clemson, SC 29634, USA
| | - Lin Li
- Computational Science Program, University of Texas at El Paso, 500 W University Ave, TX 79968, USA.,Department of Physics, University of Texas at El Paso, 500 W University Ave, TX 79968, USA
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Caremani M, Fusi L, Linari M, Reconditi M, Piazzesi G, Irving TC, Narayanan T, Irving M, Lombardi V, Brunello E. Dependence of thick filament structure in relaxed mammalian skeletal muscle on temperature and interfilament spacing. J Gen Physiol 2021; 153:211664. [PMID: 33416833 PMCID: PMC7802359 DOI: 10.1085/jgp.202012713] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Accepted: 10/28/2020] [Indexed: 11/20/2022] Open
Abstract
Contraction of skeletal muscle is regulated by structural changes in both actin-containing thin filaments and myosin-containing thick filaments, but myosin-based regulation is unlikely to be preserved after thick filament isolation, and its structural basis remains poorly characterized. Here, we describe the periodic features of the thick filament structure in situ by high-resolution small-angle x-ray diffraction and interference. We used both relaxed demembranated fibers and resting intact muscle preparations to assess whether thick filament regulation is preserved in demembranated fibers, which have been widely used for previous studies. We show that the thick filaments in both preparations exhibit two closely spaced axial periodicities, 43.1 nm and 45.5 nm, at near-physiological temperature. The shorter periodicity matches that of the myosin helix, and x-ray interference between the two arrays of myosin in the bipolar filament shows that all zones of the filament follow this periodicity. The 45.5-nm repeat has no helical component and originates from myosin layers closer to the filament midpoint associated with the titin super-repeat in that region. Cooling relaxed or resting muscle, which partially mimics the effects of calcium activation on thick filament structure, disrupts the helical order of the myosin motors, and they move out from the filament backbone. Compression of the filament lattice of demembranated fibers by 5% Dextran, which restores interfilament spacing to that in intact muscle, stabilizes the higher-temperature structure. The axial periodicity of the filament backbone increases on cooling, but in lattice-compressed fibers the periodicity of the myosin heads does not follow the extension of the backbone. Thick filament structure in lattice-compressed demembranated fibers at near-physiological temperature is similar to that in intact resting muscle, suggesting that the native structure of the thick filament is largely preserved after demembranation in these conditions, although not in the conditions used for most previous studies with this preparation.
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Affiliation(s)
| | - Luca Fusi
- Randall Centre for Cell and Molecular Biophysics, King's College London, London, UK
| | - Marco Linari
- PhysioLab, University of Florence, Florence, Italy.,Consorzio Nazionale Interuniversitario per le Scienze Fisiche della Materia, Firenze, Italy
| | - Massimo Reconditi
- PhysioLab, University of Florence, Florence, Italy.,Consorzio Nazionale Interuniversitario per le Scienze Fisiche della Materia, Firenze, Italy
| | | | - Thomas C Irving
- Center for Synchrotron Radiation Research and Instrumentation and Department of Biological Sciences, Illinois Institute of Technology, Chicago, IL
| | | | - Malcolm Irving
- Randall Centre for Cell and Molecular Biophysics, King's College London, London, UK
| | | | - Elisabetta Brunello
- PhysioLab, University of Florence, Florence, Italy.,Randall Centre for Cell and Molecular Biophysics, King's College London, London, UK
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47
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Harris SP. Making waves: A proposed new role for myosin-binding protein C in regulating oscillatory contractions in vertebrate striated muscle. J Gen Physiol 2020; 153:211574. [PMID: 33275758 PMCID: PMC7721898 DOI: 10.1085/jgp.202012729] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Myosin-binding protein C (MyBP-C) is a critical regulator of muscle performance that was first identified through its strong binding interactions with myosin, the force-generating protein of muscle. Almost simultaneously with its discovery, MyBP-C was soon found to bind to actin, the physiological catalyst for myosin’s activity. However, the two observations posed an apparent paradox, in part because interactions of MyBP-C with myosin were on the thick filament, whereas MyBP-C interactions with actin were on the thin filament. Despite the intervening decades since these initial discoveries, it is only recently that the dual binding modes of MyBP-C are becoming reconciled in models that place MyBP-C at a central position between actin and myosin, where MyBP-C alternately stabilizes a newly discovered super-relaxed state (SRX) of myosin on thick filaments in resting muscle and then prolongs the “on” state of actin on thin filaments in active muscle. Recognition of these dual, alternating functions of MyBP-C reveals how it is central to the regulation of both muscle contraction and relaxation. The purpose of this Viewpoint is to briefly summarize the roles of MyBP-C in binding to myosin and actin and then to highlight a possible new role for MyBP-C in inducing and damping oscillatory waves of contraction and relaxation. Because the contractile waves bear similarity to cycles of contraction and relaxation in insect flight muscles, which evolved for fast, energetically efficient contraction, the ability of MyBP-C to damp so-called spontaneous oscillatory contractions (SPOCs) has broad implications for previously unrecognized regulatory mechanisms in vertebrate striated muscle. While the molecular mechanisms by which MyBP-C can function as a wave maker or a wave breaker are just beginning to be explored, it is likely that MyBP-C dual interactions with both myosin and actin will continue to be important for understanding the new functions of this enigmatic protein.
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Yarwood SJ. Special Issue on "New Advances in Cyclic AMP Signalling"-An Editorial Overview. Cells 2020; 9:cells9102274. [PMID: 33053803 PMCID: PMC7599692 DOI: 10.3390/cells9102274] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Accepted: 10/10/2020] [Indexed: 02/07/2023] Open
Abstract
The cyclic nucleotides 3′,5′-adenosine monophosphate (cyclic AMP) signalling system underlies the control of many biological events and disease processes in man. Cyclic AMP is synthesised by adenylate cyclase (AC) enzymes in order to activate effector proteins and it is then degraded by phosphodiesterase (PDE) enzymes. Research in recent years has identified a range of cell-type-specific cyclic AMP effector proteins, including protein kinase A (PKA), exchange factor directly activated by cyclic AMP (EPAC), cyclic AMP responsive ion channels (CICs), and the Popeye domain containing (POPDC) proteins, which participate in different signalling mechanisms. In addition, recent advances have revealed new mechanisms of action for cyclic AMP signalling, including new effectors and new levels of compartmentalization into nanodomains, involving AKAP proteins and targeted adenylate cyclase and phosphodiesterase enzymes. This Special Issue contains 21 papers that highlight advances in our current understanding of the biology of compartmentlised cyclic AMP signalling. This ranges from issues of pathogenesis and associated molecular pathways, functional assessment of novel nanodomains, to the development of novel tool molecules and new techniques for imaging cyclic AMP compartmentilisation. This editorial aims to summarise these papers within the wider context of cyclic AMP signalling.
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Affiliation(s)
- Stephen John Yarwood
- Institute of Biological Chemistry, Biophysics and Bioengineering, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh Campus, Edinburgh EH14 4AS, UK
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49
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Synchrotron radiation imaging analysis of neural damage in mouse soleus muscle. Sci Rep 2020; 10:4555. [PMID: 32165699 PMCID: PMC7067770 DOI: 10.1038/s41598-020-61599-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Accepted: 02/27/2020] [Indexed: 11/17/2022] Open
Abstract
Damage to lower limb muscles requires accurate analysis of the muscular condition via objective microscopic diagnosis. However, microscopic tissue analysis may cause deformation of the tissue structure due to injury induced by external factors during tissue sectioning. To substantiate these muscle injuries, we used synchrotron X-ray imaging technology to project extremely small objects, provide three-dimensional microstructural analysis as extracted samples. In this study, we used mice as experimental animals to create soleus muscle models with various nerve injuries. We morphologically analyzed and quantified the damaged Section and Crush muscles, respectively, via three-dimensional visualization using synchrotron radiation X-ray imaging to diagnose muscle injury. Results of this study can also be used as basic data in the medical imaging field.
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Abstract
The heart is an extraordinarily versatile pump, finely tuned to respond to a multitude of demands. Given the heart pumps without rest for decades its efficiency is particularly relevant. Although many proteins in the heart are essential for viability, the non-essential components can attract numerous mutations which can cause disease, possibly through alterations in pumping efficiency. Of these, myosin binding protein C is strongly over-represented with ~ 40% of all known mutations in hypertrophic cardiomyopathy. Therefore, a complete understanding of its molecular function in the cardiac sarcomere is warranted. In this review, we revisit contemporary and classical literature to clarify both the current standing of this fast-moving field and frame future unresolved questions. To date, much effort has been directed at understanding MyBP-C function on either thick or thin filaments. Here we aim to focus questions on how MyBP-C functions at a molecular level in the context of both the thick and thin filaments together. A concept that emerges is MyBP-C acts to govern interactions on two levels; controlling myosin access to the thin filament by sequestration on the thick filament, and controlling the activation state and access of myosin to its binding sites on the thin filament. Such affects are achieved through directed interactions mediated by phosphorylation (of MyBP-C and other sarcomeric components) and calcium.
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