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Steczina S, Mohran S, Bailey LRJ, McMillen TS, Kooiker KB, Wood NB, Davis J, Previs MJ, Olivotto I, Pioner JM, Geeves MA, Poggesi C, Regnier M. MYBPC3-c.772G>A mutation results in haploinsufficiency and altered myosin cycling kinetics in a patient induced stem cell derived cardiomyocyte model of hypertrophic cardiomyopathy. J Mol Cell Cardiol 2024; 191:27-39. [PMID: 38648963 PMCID: PMC11116032 DOI: 10.1016/j.yjmcc.2024.04.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/13/2023] [Revised: 03/13/2024] [Accepted: 04/16/2024] [Indexed: 04/25/2024]
Abstract
Approximately 40% of hypertrophic cardiomyopathy (HCM) mutations are linked to the sarcomere protein cardiac myosin binding protein-C (cMyBP-C). These mutations are either classified as missense mutations or truncation mutations. One mutation whose nature has been inconsistently reported in the literature is the MYBPC3-c.772G > A mutation. Using patient-derived human induced pluripotent stem cells differentiated to cardiomyocytes (hiPSC-CMs), we have performed a mechanistic study of the structure-function relationship for this MYBPC3-c.772G > A mutation versus a mutation corrected, isogenic cell line. Our results confirm that this mutation leads to exon skipping and mRNA truncation that ultimately suggests ∼20% less cMyBP-C protein (i.e., haploinsufficiency). This, in turn, results in increased myosin recruitment and accelerated myofibril cycling kinetics. Our mechanistic studies suggest that faster ADP release from myosin is a primary cause of accelerated myofibril cross-bridge cycling due to this mutation. Additionally, the reduction in force generating heads expected from faster ADP release during isometric contractions is outweighed by a cMyBP-C phosphorylation mediated increase in myosin recruitment that leads to a net increase of myofibril force, primarily at submaximal calcium activations. These results match well with our previous report on contractile properties from myectomy samples of the patients from whom the hiPSC-CMs were generated, demonstrating that these cell lines are a good model to study this pathological mutation and extends our understanding of the mechanisms of altered contractile properties of this HCM MYBPC3-c.772G > A mutation.
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Affiliation(s)
- Sonette Steczina
- Department of Bioengineering, University of Washington, Seattle, WA 98109, USA; Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA 98109, USA
| | - Saffie Mohran
- Department of Bioengineering, University of Washington, Seattle, WA 98109, USA; Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA 98109, USA
| | - Logan R J Bailey
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA 98109, USA; Molecular and Cellular Biology, University of Washington, Seattle, WA 98109, USA; Department of Lab Medicine and Pathology, University of Washington, Seattle, WA 98109, USA
| | - Timothy S McMillen
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA 98109, USA; Department of Anesthesiology and Pain Medicine, University of Washington, Seattle, WA 98109, USA; Center for Translational Muscle Research, University of Washington, Seattle, WA 98109, USA
| | - Kristina B Kooiker
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA 98109, USA; Division of Cardiology, Department of Medicine, University of Washington, Seattle, WA 98109, USA
| | - Neil B Wood
- Department of Molecular Physiology and Biophysics, University of Vermont, Burlington, VT 05404, USA
| | - Jennifer Davis
- Department of Bioengineering, University of Washington, Seattle, WA 98109, USA; Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA 98109, USA; Department of Lab Medicine and Pathology, University of Washington, Seattle, WA 98109, USA
| | - Michael J Previs
- Department of Molecular Physiology and Biophysics, University of Vermont, Burlington, VT 05404, USA
| | - Iacopo Olivotto
- Department of Experimental and Clinical Medicine, Division of Physiology, University of Florence, Italy
| | | | | | - Corrado Poggesi
- Department of Experimental and Clinical Medicine, Division of Physiology, University of Florence, Italy
| | - Michael Regnier
- Department of Bioengineering, University of Washington, Seattle, WA 98109, USA; Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA 98109, USA; Center for Translational Muscle Research, University of Washington, Seattle, WA 98109, USA.
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2
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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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Kelly CM, Martin JL, Previs MJ. Myosin folding boosts solubility in cardiac muscle sarcomeres. JCI Insight 2024; 9:e178131. [PMID: 38483507 PMCID: PMC11141871 DOI: 10.1172/jci.insight.178131] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2023] [Accepted: 03/05/2024] [Indexed: 04/23/2024] Open
Abstract
The polymerization of myosin molecules into thick filaments in muscle sarcomeres is essential for cardiac contractility, with the attenuation of interactions between the heads of myosin molecules within the filaments being proposed to result in hypercontractility, as observed in hypertrophic cardiomyopathy (HCM). However, experimental evidence demonstrates that the structure of these giant macromolecular complexes is highly dynamic, with molecules exchanging between the filaments and a pool of soluble molecules on the minute timescale. Therefore, we sought to test the hypothesis that the enhancement of interactions between the heads of myosin molecules within thick filaments limits the mobility of myosin by taking advantage of mavacamten, a small molecule approved for the treatment of HCM. Myosin molecules were labeled in vivo with a green fluorescent protein (GFP) and imaged in intact hearts using multiphoton microscopy. Treatment of the intact hearts with mavacamten resulted in an unexpected > 5-fold enhancement in GFP-myosin mobility within the sarcomere. In vitro biochemical assays suggested that mavacamten enhanced the mobility of GFP-myosin by increasing the solubility of myosin molecules, through the stabilization of a compact/folded conformation of the molecules, once disassociated from the thick filaments. These findings provide alternative insight into the mechanisms by which molecules exchange into and out of thick filaments and have implications for how mavacamten may affect cardiac contractility.
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Affiliation(s)
- Colleen M Kelly
- Molecular Physiology and Biophysics Department, Larner College of Medicine, University of Vermont, Burlington, Vermont, USA
| | - Jody L Martin
- Department of Pharmacology, University of California, Davis, Davis, California, USA
| | - Michael J Previs
- Molecular Physiology and Biophysics Department, Larner College of Medicine, University of Vermont, Burlington, Vermont, USA
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Adam I, Riebel K, Stål P, Wood N, Previs MJ, Elemans CPH. Daily vocal exercise is necessary for peak performance singing in a songbird. Nat Commun 2023; 14:7787. [PMID: 38086817 PMCID: PMC10716414 DOI: 10.1038/s41467-023-43592-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Accepted: 11/13/2023] [Indexed: 12/18/2023] Open
Abstract
Vocal signals, including human speech and birdsong, are produced by complicated, precisely coordinated body movements, whose execution is fitness-determining in resource competition and mate choice. While the acquisition and maintenance of motor skills generally requires practice to develop and maintain both motor circuitry and muscle performance, it is unknown whether vocal muscles, like limb muscles, exhibit exercise-induced plasticity. Here, we show that juvenile and adult zebra finches (Taeniopygia castanotis) require daily vocal exercise to first gain and subsequently maintain peak vocal muscle performance. Experimentally preventing male birds from singing alters both vocal muscle physiology and vocal performance within days. Furthermore, we find females prefer song of vocally exercised males in choice experiments. Vocal output thus contains information on recent exercise status, and acts as an honest indicator of past exercise investment in songbirds, and possibly in all vocalising vertebrates.
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Affiliation(s)
- Iris Adam
- Department of Biology, University of Southern Denmark, Odense, Denmark.
| | - Katharina Riebel
- Institute of Biology, Animal Sciences & Health, Leiden University, Leiden, The Netherlands
| | - Per Stål
- Department of Integrative Medical Biology, Umea University, Umeå, Sweden
| | - Neil Wood
- Department of Molecular Physiology and Biophysics, Larner College of Medicine, University of Vermont, Burlington, NJ, USA
| | - Michael J Previs
- Department of Molecular Physiology and Biophysics, Larner College of Medicine, University of Vermont, Burlington, NJ, USA
| | - Coen P H Elemans
- Department of Biology, University of Southern Denmark, Odense, Denmark.
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5
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Kelly CM, Martin JL, Coseno M, Previs MJ. Visualization of cardiac thick filament dynamics in ex vivo heart preparations. J Mol Cell Cardiol 2023; 185:88-98. [PMID: 37923195 PMCID: PMC10959293 DOI: 10.1016/j.yjmcc.2023.10.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Revised: 10/27/2023] [Accepted: 10/30/2023] [Indexed: 11/07/2023]
Abstract
RATIONALE Cardiac muscle cells are terminally differentiated after birth and must beat continually throughout one's lifetime. This mechanical process is driven by the sliding of actin-based thin filaments along myosin-based thick filaments, organized within sarcomeres. Despite costly energetic demand, the half-life of the proteins that comprise the cardiac thick filaments is ∼10 days, with individual molecules being replaced stochastically, by unknown mechanisms. OBJECTIVES To allow for the stochastic replacement of molecules, we hypothesized that the structure of thick filaments must be highly dynamic in vivo. METHODS AND RESULTS To test this hypothesis in adult mouse hearts, we replaced a fraction of the endogenous myosin regulatory light chain (RLC), a component of thick filaments, with GFP-labeled RLC by adeno-associated viral (AAV) transduction. The RLC-GFP was properly localized to the heads of the myosin molecules within thick filaments in ex vivo heart preparations and had no effect on heart size or actin filament siding in vitro. However, the localization of the RLC-GFP molecules was highly mobile, changing its position within the sarcomere on the minute timescale, when quantified by fluorescence recovery after photobleaching (FRAP) using multiphoton microscopy. Interestingly, RLC-GFP mobility was restricted to within the boundaries of single sarcomeres. When cardiomyocytes were lysed, the RLC-GFP remained strongly bound to myosin heavy chain, and the intact myosin molecules adopted a folded, compact configuration, when disassociated from the filaments at physiological ionic conditions. CONCLUSIONS These data demonstrate that the structure of the thick filament is highly dynamic in the intact heart, with a rate of molecular exchange into and out of thick filaments that is ∼1500 times faster than that required for the replacement of molecules through protein synthesis or degradation.
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Affiliation(s)
- Colleen M Kelly
- Molecular Physiology and Biophysics Department, University of Vermont, Larner College of Medicine, Burlington, VT 05405, United States of America
| | - Jody L Martin
- Department of Pharmacology, University of California, Davis, Davis, CA 90095, United States of America
| | - Molly Coseno
- Fluidic Analytics, The Paddocks Business Centre, Cambridge CB1 8DH, United Kingdom
| | - Michael J Previs
- Molecular Physiology and Biophysics Department, University of Vermont, Larner College of Medicine, Burlington, VT 05405, United States of America.
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6
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Thompson AD, Wagner MJ, Rodriguez J, Malhotra A, Vander Roest S, Lilienthal U, Shao H, Vignesh M, Weber K, Yob JM, Prosser BL, Helms AS, Gestwicki JE, Ginsburg D, Day SM. An Unbiased Screen Identified the Hsp70-BAG3 Complex as a Regulator of Myosin-Binding Protein C3. JACC Basic Transl Sci 2023; 8:1198-1211. [PMID: 37791314 PMCID: PMC10544073 DOI: 10.1016/j.jacbts.2023.04.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Revised: 04/17/2023] [Accepted: 04/18/2023] [Indexed: 10/05/2023]
Abstract
Variants in the gene myosin-binding protein C3 (MYBPC3) account for approximately 50% of familial hypertrophic cardiomyopathy (HCM), leading to reduced levels of myosin-binding protein C3 (MyBP-C), the protein product made by gene MYBPC3. Elucidation of the pathways that regulate MyBP-C protein homeostasis could uncover new therapeutic strategies. Toward this goal, we screened a library of 2,426 bioactive compounds and identified JG98, an allosteric modulator of heat shock protein 70 that inhibits interaction with Bcl-2-associated athanogene (BAG) domain co-chaperones. JG98 reduces MyBP-C protein levels. Furthermore, genetic reduction of BAG3 phenocopies treatment with JG-98 by reducing MYBP-C protein levels.. Thus, an unbiased compound screen identified the heat shock protein 70-BAG3 complex as a regulator of MyBP-C stability.
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Affiliation(s)
- Andrea D. Thompson
- Department of Internal Medicine, Division of Cardiovascular Medicine, University of Michigan, Ann Arbor, Michigan, USA
| | - Marcus J. Wagner
- Department of Internal Medicine, Division of Cardiovascular Medicine and Cardiovascular Institute, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Juliani Rodriguez
- Department of Internal Medicine, Division of Cardiovascular Medicine, University of Michigan, Ann Arbor, Michigan, USA
| | - Alok Malhotra
- Department of Internal Medicine, Division of Cardiovascular Medicine, University of Michigan, Ann Arbor, Michigan, USA
| | - Steve Vander Roest
- Center for Chemical Genomics, Life Sciences Institute, University of Michigan, Ann Arbor, Michigan, USA
| | - Ulla Lilienthal
- Department of Internal Medicine, Division of Cardiovascular Medicine, University of Michigan, Ann Arbor, Michigan, USA
| | - Hao Shao
- Institute for Neurodegenerative Diseases and Department of Pharmaceutical Chemistry, University of California San Francisco, San Francisco, California, USA
| | - Mathav Vignesh
- Department of Internal Medicine, Division of Cardiovascular Medicine, University of Michigan, Ann Arbor, Michigan, USA
| | - Keely Weber
- Department of Internal Medicine, Division of Cardiovascular Medicine, University of Michigan, Ann Arbor, Michigan, USA
| | - Jaime M. Yob
- Department of Internal Medicine, Division of Cardiovascular Medicine and Cardiovascular Institute, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Benjamin L. Prosser
- Department of Physiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Adam S. Helms
- Department of Internal Medicine, Division of Cardiovascular Medicine, University of Michigan, Ann Arbor, Michigan, USA
| | - Jason E. Gestwicki
- Institute for Neurodegenerative Diseases and Department of Pharmaceutical Chemistry, University of California San Francisco, San Francisco, California, USA
| | - David Ginsburg
- Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan, USA
- Department of Human Genetics, University of Michigan, Ann Arbor, Michigan, USA
- Department of Pediatrics, University of Michigan, Ann Arbor, Michigan, USA
- Howard Hughes Medical Institute, Chevy Chase, Maryland, USA
- The Life Sciences Institute, University of Michigan, Ann Arbor, Michigan, USA
| | - Sharlene M. Day
- Department of Internal Medicine, Division of Cardiovascular Medicine and Cardiovascular Institute, University of Pennsylvania, Philadelphia, Pennsylvania, USA
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7
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Barefield DY, Alvarez-Arce A, Araujo KN. Mechanisms of Sarcomere Protein Mutation-Induced Cardiomyopathies. Curr Cardiol Rep 2023; 25:473-484. [PMID: 37060436 PMCID: PMC11141690 DOI: 10.1007/s11886-023-01876-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 03/30/2023] [Indexed: 04/16/2023]
Abstract
PURPOSE OF REVIEW The pace of identifying cardiomyopathy-associated mutations and advances in our understanding of sarcomere function that underlies many cardiomyopathies has been remarkable. Here, we aim to synthesize how these advances have led to the promising new treatments that are being developed to treat cardiomyopathies. RECENT FINDINGS The genomics era has identified and validated many genetic causes of hypertrophic and dilated cardiomyopathies. Recent advances in our mechanistic understanding of sarcomere pathophysiology include high-resolution molecular models of sarcomere components and the identification of the myosin super-relaxed state. The advances in our understanding of sarcomere function have yielded several therapeutic agents that are now in development and clinical use to correct contractile dysfunction-mediated cardiomyopathy. New genes linked to cardiomyopathy include targets with limited clinical evidence and require additional investigation. Large portions of cardiomyopathy with family history remain genetically undiagnosed and may be due to polygenic disease.
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Affiliation(s)
- David Y Barefield
- Department of Cell and Molecular Physiology, Loyola University Chicago, 2160 S. 1st Ave, Maywood, IL, 60153, USA.
| | - Alejandro Alvarez-Arce
- Department of Cell and Molecular Physiology, Loyola University Chicago, 2160 S. 1st Ave, Maywood, IL, 60153, USA
| | - Kelly N Araujo
- Department of Cell and Molecular Physiology, Loyola University Chicago, 2160 S. 1st Ave, Maywood, IL, 60153, USA
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De Lange WJ, Farrell ET, Hernandez JJ, Stempien A, Kreitzer CR, Jacobs DR, Petty DL, Moss RL, Crone WC, Ralphe JC. cMyBP-C ablation in human engineered cardiac tissue causes progressive Ca2+-handling abnormalities. J Gen Physiol 2023; 155:e202213204. [PMID: 36893011 PMCID: PMC10038829 DOI: 10.1085/jgp.202213204] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Revised: 01/02/2023] [Accepted: 02/14/2023] [Indexed: 03/10/2023] Open
Abstract
Truncation mutations in cardiac myosin binding protein C (cMyBP-C) are common causes of hypertrophic cardiomyopathy (HCM). Heterozygous carriers present with classical HCM, while homozygous carriers present with early onset HCM that rapidly progress to heart failure. We used CRISPR-Cas9 to introduce heterozygous (cMyBP-C+/-) and homozygous (cMyBP-C-/-) frame-shift mutations into MYBPC3 in human iPSCs. Cardiomyocytes derived from these isogenic lines were used to generate cardiac micropatterns and engineered cardiac tissue constructs (ECTs) that were characterized for contractile function, Ca2+-handling, and Ca2+-sensitivity. While heterozygous frame shifts did not alter cMyBP-C protein levels in 2-D cardiomyocytes, cMyBP-C+/- ECTs were haploinsufficient. cMyBP-C-/- cardiac micropatterns produced increased strain with normal Ca2+-handling. After 2 wk of culture in ECT, contractile function was similar between the three genotypes; however, Ca2+-release was slower in the setting of reduced or absent cMyBP-C. At 6 wk in ECT culture, the Ca2+-handling abnormalities became more pronounced in both cMyBP-C+/- and cMyBP-C-/- ECTs, and force production became severely depressed in cMyBP-C-/- ECTs. RNA-seq analysis revealed enrichment of differentially expressed hypertrophic, sarcomeric, Ca2+-handling, and metabolic genes in cMyBP-C+/- and cMyBP-C-/- ECTs. Our data suggest a progressive phenotype caused by cMyBP-C haploinsufficiency and ablation that initially is hypercontractile, but progresses to hypocontractility with impaired relaxation. The severity of the phenotype correlates with the amount of cMyBP-C present, with more severe earlier phenotypes observed in cMyBP-C-/- than cMyBP-C+/- ECTs. We propose that while the primary effect of cMyBP-C haploinsufficiency or ablation may relate to myosin crossbridge orientation, the observed contractile phenotype is Ca2+-mediated.
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Affiliation(s)
- Willem J. De Lange
- Departments of Pediatrics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA
| | - Emily T. Farrell
- Departments of Pediatrics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA
| | - Jonathan J. Hernandez
- Departments of Pediatrics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA
| | - Alana Stempien
- Departments of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, USA
- Wisconsin Institute for Discovery, University of Wisconsin-Madison, Madison, WI, USA
| | - Caroline R. Kreitzer
- Departments of Pediatrics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA
| | - Derek R. Jacobs
- Departments of Pediatrics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA
| | - Dominique L. Petty
- Departments of Pediatrics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA
| | - Richard L. Moss
- Cell and Regenerative Biology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA
| | - Wendy C. Crone
- Departments of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, USA
- Wisconsin Institute for Discovery, University of Wisconsin-Madison, Madison, WI, USA
- Engineering Physics, University of Wisconsin-Madison, Madison, WI, USA
- Materials Science and Engineering, University of Wisconsin-Madison, Madison, WI, USA
| | - J. Carter Ralphe
- Departments of Pediatrics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA
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9
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Adam I, Riebel K, St L P, Wood NB, Previs MJ, Elemans CPH. Peak performance singing requires daily vocal exercise in songbirds. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.23.529633. [PMID: 36865130 PMCID: PMC9980080 DOI: 10.1101/2023.02.23.529633] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/25/2023]
Abstract
Vocal signals mediate much of human and non-human communication. Key performance traits - such as repertoire size, speed and accuracy of delivery - affect communication efficacy in fitness-decisive contexts such as mate choice and resource competition 1 . Specialized fast vocal muscles 2,3 are central to accurate sound production 4 , but it is unknown whether vocal, like limb muscles 5,6 , need exercise to gain and maintain peak performance 7,8 . Here, we show that for song development in juvenile songbirds, the closest analogue to human speech acquisition 9 , regular vocal muscle exercise is crucial to achieve adult peak muscle performance. Furthermore, adult vocal muscle performance reduces within two days of abolishing exercise, leading to downregulation of critical proteins transforming fast to slower muscle fibre types. Daily vocal exercise is thus required to both gain and maintain peak vocal muscle performance, and if absent changes vocal output. We show that conspecifics can detect these acoustic changes and females prefer the song of exercised males. Song thus contains information on recent exercise status of the sender. Daily investment in vocal exercise to maintain peak performance is an unrecognized cost of singing and could explain why many birds sing daily even under adverse conditions 10 . Because neural regulation of syringeal and laryngeal muscle plasticity is equivalent, vocal output may reflect recent exercise status in all vocalizing vertebrates.
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10
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Rasicci DV, Ge J, Milburn GN, Wood NB, Pruznak AM, Lang CH, Previs MJ, Campbell KS, Yengo CM. Cardiac myosin motor deficits are associated with left ventricular dysfunction in human ischemic heart failure. Am J Physiol Heart Circ Physiol 2023; 324:H198-H209. [PMID: 36525480 PMCID: PMC9829461 DOI: 10.1152/ajpheart.00272.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Revised: 12/09/2022] [Accepted: 12/12/2022] [Indexed: 12/23/2022]
Abstract
During ischemic heart failure (IHF), cardiac muscle contraction is typically impaired, though the molecular changes within the myocardium are not fully understood. Thus, we aimed to characterize the biophysical properties of cardiac myosin in IHF. Cardiac tissue was harvested from 10 age-matched males, either with a history of IHF or nonfailing (NF) controls that had no history of structural or functional cardiac abnormalities. Clinical measures before cardiac biopsy demonstrated significant differences in measures of ejection fraction and left ventricular dimensions. Myofibrils and myosin were extracted from left ventricular free wall cardiac samples. There were no changes in myofibrillar ATPase activity or calcium sensitivity between groups. Using isolated myosin, we found a 15% reduction in the IHF group in actin sliding velocity in the in vitro motility assay, which was observed in the absence of a myosin isoform shift. Oxidative damage (carbonylation) of isolated myosin was compared, in which there were no significant differences between groups. Synthetic thick filaments were formed from purified myosin and the ATPase activity was similar in both basal and actin-activated conditions (20 µM actin). Correlation analysis and Deming linear regression were performed between all studied parameters, in which we found statistically significant correlations between clinical measures of contractility with molecular measures of sliding velocity and ELC carbonylation. Our data indicate that subtle deficits in myosin mechanochemical properties are associated with reduced contractile function and pathological remodeling of the heart, suggesting that the myosin motor may be an effective pharmacological intervention in ischemia.NEW & NOTEWORTHY Ischemic heart failure is associated with impairments in contractile performance of the heart. This study revealed that cardiac myosin isolated from patients with ischemic heart failure had reduced mechanical activity, which correlated with the impaired clinical phenotype of the patients. The results suggest that restoring myosin function with pharmacological intervention may be a viable method for therapeutic intervention.
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Affiliation(s)
- D. V. Rasicci
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania
- Department of Pathology, Anatomy, and Laboratory Medicine, West Virginia University School of Medicine, Morgantown, West Virginia
| | - J. Ge
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania
| | - G. N. Milburn
- Department of Physiology, University of Kentucky, Lexington, Kentucky
| | - N. B. Wood
- Department of Molecular Physiology and Biophysics, University of Vermont, Burlington, Vermont
| | - A. M. Pruznak
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania
| | - C. H. Lang
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania
| | - M. J. Previs
- Department of Molecular Physiology and Biophysics, University of Vermont, Burlington, Vermont
| | - K. S. Campbell
- Department of Physiology, University of Kentucky, Lexington, Kentucky
- Division of Cardiovascular Medicine, University of Kentucky, Lexington, Kentucky
| | - C. M. Yengo
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania
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11
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Li J, Rahmani H, Abbasi Yeganeh F, Rastegarpouyani H, Taylor DW, Wood NB, Previs MJ, Iwamoto H, Taylor KA. Structure of the Flight Muscle Thick Filament from the Bumble Bee, Bombus ignitus, at 6 Å Resolution. Int J Mol Sci 2022; 24:377. [PMID: 36613818 PMCID: PMC9820631 DOI: 10.3390/ijms24010377] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Revised: 12/12/2022] [Accepted: 12/13/2022] [Indexed: 12/28/2022] Open
Abstract
Four insect orders have flight muscles that are both asynchronous and indirect; they are asynchronous in that the wingbeat frequency is decoupled from the frequency of nervous stimulation and indirect in that the muscles attach to the thoracic exoskeleton instead of directly to the wing. Flight muscle thick filaments from two orders, Hemiptera and Diptera, have been imaged at a subnanometer resolution, both of which revealed a myosin tail arrangement referred to as “curved molecular crystalline layers”. Here, we report a thick filament structure from the indirect flight muscles of a third insect order, Hymenoptera, the Asian bumble bee Bombus ignitus. The myosin tails are in general agreement with previous determinations from Lethocerus indicus and Drosophila melanogaster. The Skip 2 region has the same unusual structure as found in Lethocerus indicus thick filaments, an α-helix discontinuity is also seen at Skip 4, but the orientation of the Skip 1 region on the surface of the backbone is less angled with respect to the filament axis than in the other two species. The heads are disordered as in Drosophila, but we observe no non-myosin proteins on the backbone surface that might prohibit the ordering of myosin heads onto the thick filament backbone. There are strong structural similarities among the three species in their non-myosin proteins within the backbone that suggest how one previously unassigned density in Lethocerus might be assigned. Overall, the structure conforms to the previously observed pattern of high similarity in the myosin tail arrangement, but differences in the non-myosin proteins.
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Affiliation(s)
- Jiawei Li
- Institute of Molecular Biophysics, Florida State University, Tallahassee, FL 32306-4380, USA
| | - Hamidreza Rahmani
- Institute of Molecular Biophysics, Florida State University, Tallahassee, FL 32306-4380, USA
| | - Fatemeh Abbasi Yeganeh
- Institute of Molecular Biophysics, Florida State University, Tallahassee, FL 32306-4380, USA
| | - Hosna Rastegarpouyani
- Institute of Molecular Biophysics, Florida State University, Tallahassee, FL 32306-4380, USA
| | - Dianne W. Taylor
- Institute of Molecular Biophysics, Florida State University, Tallahassee, FL 32306-4380, USA
| | - Neil B. Wood
- Department of Molecular Physiology & Biophysics, University of Vermont, Larner College of Medicine, Burlington, VT 05405, USA
| | - Michael J. Previs
- Department of Molecular Physiology & Biophysics, University of Vermont, Larner College of Medicine, Burlington, VT 05405, USA
| | - Hiroyuki Iwamoto
- Scattering and Imaging Division, Japan Synchrotron Radiation Research Institute, SPring-8, Hyogo 679-5198, Japan
| | - Kenneth A. Taylor
- Institute of Molecular Biophysics, Florida State University, Tallahassee, FL 32306-4380, USA
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12
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Application of Long-Read Nanopore Sequencing to the Search for Mutations in Hypertrophic Cardiomyopathy. Int J Mol Sci 2022; 23:ijms232415845. [PMID: 36555486 PMCID: PMC9779642 DOI: 10.3390/ijms232415845] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2022] [Revised: 12/10/2022] [Accepted: 12/10/2022] [Indexed: 12/15/2022] Open
Abstract
Increasing evidence suggests that both coding and non-coding regions of sarcomeric protein genes can contribute to hypertrophic cardiomyopathy (HCM). Here, we introduce an experimental workflow (tested on four patients) for complete sequencing of the most common HCM genes (MYBPC3, MYH7, TPM1, TNNT2, and TNNI3) via long-range PCR, Oxford Nanopore Technology (ONT) sequencing, and bioinformatic analysis. We applied Illumina and Sanger sequencing to validate the results, FastQC, Qualimap, and MultiQC for quality evaluations, MiniMap2 to align data, Clair3 to call and phase variants, and Annovar's tools and CADD to assess pathogenicity of variants. We could not amplify the region encompassing exons 6-12 of MYBPC3. A higher sequencing error rate was observed with ONT (6.86-6.92%) than with Illumina technology (1.14-1.35%), mostly for small indels. Pathogenic variant p.Gln1233Ter and benign polymorphism p.Arg326Gln in MYBPC3 in a heterozygous state were found in one patient. We demonstrated the ability of ONT to phase single-nucleotide variants, enabling direct haplotype determination for genes TNNT2 and TPM1. These findings highlight the importance of long-range PCR efficiency, as well as lower accuracy of variant calling by ONT than by Illumina technology; these differences should be clarified prior to clinical application of the ONT method.
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13
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Wood NB, Kelly CM, O’Leary TS, Martin JL, Previs MJ. Cardiac Myosin Filaments are Maintained by Stochastic Protein Replacement. Mol Cell Proteomics 2022; 21:100274. [PMID: 35921914 PMCID: PMC9528119 DOI: 10.1016/j.mcpro.2022.100274] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 07/08/2022] [Accepted: 07/19/2022] [Indexed: 01/18/2023] Open
Abstract
Myosin and myosin-binding protein C are exquisitely organized into giant filamentous macromolecular complexes within cardiac muscle sarcomeres, yet these proteins must be continually replaced to maintain contractile fidelity. The overall hypothesis that myosin filament structure is dynamic and allows for the stochastic replacement of individual components was tested in vivo, using a combination of mass spectrometry- and fluorescence-based proteomic techniques. Adult mice were fed a diet that marked all newly synthesized proteins with a stable isotope-labeled amino acid. The abundance of unlabeled and labeled proteins was quantified by high-resolution mass spectrometry over an 8-week period. The rates of change in the abundance of these proteins were well described by analytical models in which protein synthesis defined stoichiometry and protein degradation was governed by the stochastic selection of individual molecules. To test whether the whole myosin filaments or the individual components were selected for replacement, cardiac muscle was chemically skinned to remove the cellular membrane and myosin filaments were solubilized with ionic solutions. The composition of the filamentous and soluble fractions was quantified by mass spectrometry, and filament depolymerization was visualized by real-time fluorescence microscopy. Myosin molecules were preferentially extracted from ends of the filaments in the presence of the ionic solutions, and there was only a slight bias in the abundance of unlabeled molecules toward the innermost region on the myosin filaments. These data demonstrate for the first time that the newly synthesized myosin and myosin-binding protein C molecules are randomly mixed into preexisting thick filaments in vivo and the rate of mixing may not be equivalent along the length of the thick filament. These data collectively support a new model of cardiac myosin filament structure, with the filaments being dynamic macromolecular assemblies that allow for replacement of their components, rather than rigid bodies.
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Affiliation(s)
- Neil B. Wood
- Department of Molecular Physiology and Biophysics, University of Vermont, Larner College of Medicine, Burlington, Vermont, USA
| | - Colleen M. Kelly
- Department of Molecular Physiology and Biophysics, University of Vermont, Larner College of Medicine, Burlington, Vermont, USA
| | - Thomas S. O’Leary
- Department of Molecular Physiology and Biophysics, University of Vermont, Larner College of Medicine, Burlington, Vermont, USA
| | - Jody L. Martin
- Department of Pharmacology, University of California, Davis, Davis, California, USA
| | - Michael J. Previs
- Department of Molecular Physiology and Biophysics, University of Vermont, Larner College of Medicine, Burlington, Vermont, USA,For correspondence: Michael J. Previs, Department of Molecular Physiology & Biophysics, Larner College of Medicine, University of Vermont, Health Science Research Facility, 149 Beaumont Avenue, Room 108, Burlington, Vermont 05405
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14
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Kötter S, Krüger M. Protein Quality Control at the Sarcomere: Titin Protection and Turnover and Implications for Disease Development. Front Physiol 2022; 13:914296. [PMID: 35846001 PMCID: PMC9281568 DOI: 10.3389/fphys.2022.914296] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Accepted: 06/10/2022] [Indexed: 11/26/2022] Open
Abstract
Sarcomeres are mainly composed of filament and signaling proteins and are the smallest molecular units of muscle contraction and relaxation. The sarcomere protein titin serves as a molecular spring whose stiffness mediates myofilament extensibility in skeletal and cardiac muscle. Due to the enormous size of titin and its tight integration into the sarcomere, the incorporation and degradation of the titin filament is a highly complex task. The details of the molecular processes involved in titin turnover are not fully understood, but the involvement of different intracellular degradation mechanisms has recently been described. This review summarizes the current state of research with particular emphasis on the relationship between titin and protein quality control. We highlight the involvement of the proteasome, autophagy, heat shock proteins, and proteases in the protection and degradation of titin in heart and skeletal muscle. Because the fine-tuned balance of degradation and protein expression can be disrupted under pathological conditions, the review also provides an overview of previously known perturbations in protein quality control and discusses how these affect sarcomeric proteins, and titin in particular, in various disease states.
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15
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Previs MJ, O’Leary TS, Morley MP, Palmer B, LeWinter M, Yob J, Pagani FD, Petucci C, Kim MS, Margulies KB, Arany Z, Kelly DP, Day SM. Defects in the Proteome and Metabolome in Human Hypertrophic Cardiomyopathy. Circ Heart Fail 2022; 15:e009521. [PMID: 35543134 PMCID: PMC9708114 DOI: 10.1161/circheartfailure.121.009521] [Citation(s) in RCA: 32] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Defects in energetics are thought to be central to the pathophysiology of hypertrophic cardiomyopathy (HCM); yet, the determinants of ATP availability are not known. The purpose of this study is to ascertain the nature and extent of metabolic reprogramming in human HCM, and its potential impact on contractile function. METHODS We conducted proteomic and targeted, quantitative metabolomic analyses on heart tissue from patients with HCM and from nonfailing control human hearts. RESULTS In the proteomic analysis, the greatest differences observed in HCM samples compared with controls were increased abundances of extracellular matrix and intermediate filament proteins and decreased abundances of muscle creatine kinase and mitochondrial proteins involved in fatty acid oxidation. These differences in protein abundance were coupled with marked reductions in acyl carnitines, byproducts of fatty acid oxidation, in HCM samples. Conversely, the ketone body 3-hydroxybutyrate, branched chain amino acids, and their breakdown products, were all significantly increased in HCM hearts. ATP content, phosphocreatine, nicotinamide adenine dinucleotide and its phosphate derivatives, NADP and NADPH, and acetyl CoA were also severely reduced in HCM compared with control hearts. Functional assays performed on human skinned myocardial fibers demonstrated that the magnitude of observed reduction in ATP content in the HCM samples would be expected to decrease the rate of cross-bridge detachment. Moreover, left atrial size, an indicator of diastolic compliance, was inversely correlated with ATP content in hearts from patients with HCM. CONCLUSIONS HCM hearts display profound deficits in nucleotide availability with markedly reduced capacity for fatty acid oxidation and increases in ketone bodies and branched chain amino acids. These results have important therapeutic implications for the future design of metabolic modulators to treat HCM.
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Affiliation(s)
- Michael J. Previs
- Department of Molecular Physiology and Biophysics, University of Vermont, Larner College of Medicine
| | - Thomas S. O’Leary
- Department of Molecular Physiology and Biophysics, University of Vermont, Larner College of Medicine
| | - Michael P. Morley
- Division of Cardiovascular Medicine and the Penn Cardiovascular Institute, Perelman School of Medicine, University of Pennsylvania
| | - Brad Palmer
- Department of Molecular Physiology and Biophysics, University of Vermont, Larner College of Medicine
| | - Martin LeWinter
- Department of Molecular Physiology and Biophysics, University of Vermont, Larner College of Medicine
| | - Jaime Yob
- Division of Cardiovascular Medicine and the Penn Cardiovascular Institute, Perelman School of Medicine, University of Pennsylvania
| | - Francis D. Pagani
- Department of Cardiothoracic Surgery, University of Michigan School of Medicine
| | - Christopher Petucci
- Division of Cardiovascular Medicine and the Penn Cardiovascular Institute, Perelman School of Medicine, University of Pennsylvania
| | - Min-Soo Kim
- Division of Cardiovascular Medicine and the Penn Cardiovascular Institute, Perelman School of Medicine, University of Pennsylvania
| | - Kenneth B. Margulies
- Division of Cardiovascular Medicine and the Penn Cardiovascular Institute, Perelman School of Medicine, University of Pennsylvania
| | - Zoltan Arany
- Division of Cardiovascular Medicine and the Penn Cardiovascular Institute, Perelman School of Medicine, University of Pennsylvania
| | - Daniel P. Kelly
- Division of Cardiovascular Medicine and the Penn Cardiovascular Institute, Perelman School of Medicine, University of Pennsylvania
| | - Sharlene M. Day
- Division of Cardiovascular Medicine and the Penn Cardiovascular Institute, Perelman School of Medicine, University of Pennsylvania
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16
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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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17
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Critical Evaluation of Current Hypotheses for the Pathogenesis of Hypertrophic Cardiomyopathy. Int J Mol Sci 2022; 23:ijms23042195. [PMID: 35216312 PMCID: PMC8880276 DOI: 10.3390/ijms23042195] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Revised: 02/07/2022] [Accepted: 02/14/2022] [Indexed: 02/04/2023] Open
Abstract
Hereditary hypertrophic cardiomyopathy (HCM), due to mutations in sarcomere proteins, occurs in more than 1/500 individuals and is the leading cause of sudden cardiac death in young people. The clinical course exhibits appreciable variability. However, typically, heart morphology and function are normal at birth, with pathological remodeling developing over years to decades, leading to a phenotype characterized by asymmetric ventricular hypertrophy, scattered fibrosis and myofibrillar/cellular disarray with ultimate mechanical heart failure and/or severe arrhythmias. The identity of the primary mutation-induced changes in sarcomere function and how they trigger debilitating remodeling are poorly understood. Support for the importance of mutation-induced hypercontractility, e.g., increased calcium sensitivity and/or increased power output, has been strengthened in recent years. However, other ideas that mutation-induced hypocontractility or non-uniformities with contractile instabilities, instead, constitute primary triggers cannot yet be discarded. Here, we review evidence for and criticism against the mentioned hypotheses. In this process, we find support for previous ideas that inefficient energy usage and a blunted Frank–Starling mechanism have central roles in pathogenesis, although presumably representing effects secondary to the primary mutation-induced changes. While first trying to reconcile apparently diverging evidence for the different hypotheses in one unified model, we also identify key remaining questions and suggest how experimental systems that are built around isolated primarily expressed proteins could be useful.
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18
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Riley LA, Zhang X, Douglas CM, Mijares JM, Hammers DW, Wolff CA, Wood NB, Olafson HR, Du P, Labeit S, Previs MJ, Wang ET, Esser KA. The skeletal muscle circadian clock regulates titin splicing through RBM20. eLife 2022; 11:76478. [PMID: 36047761 PMCID: PMC9473687 DOI: 10.7554/elife.76478] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Accepted: 08/31/2022] [Indexed: 02/01/2023] Open
Abstract
Circadian rhythms are maintained by a cell-autonomous, transcriptional-translational feedback loop known as the molecular clock. While previous research suggests a role of the molecular clock in regulating skeletal muscle structure and function, no mechanisms have connected the molecular clock to sarcomere filaments. Utilizing inducible, skeletal muscle specific, Bmal1 knockout (iMSBmal1-/-) mice, we showed that knocking out skeletal muscle clock function alters titin isoform expression using RNAseq, liquid chromatography-mass spectrometry, and sodium dodecyl sulfate-vertical agarose gel electrophoresis. This alteration in titin's spring length resulted in sarcomere length heterogeneity. We demonstrate the direct link between altered titin splicing and sarcomere length in vitro using U7 snRNPs that truncate the region of titin altered in iMSBmal1-/- muscle. We identified a mechanism whereby the skeletal muscle clock regulates titin isoform expression through transcriptional regulation of Rbm20, a potent splicing regulator of titin. Lastly, we used an environmental model of circadian rhythm disruption and identified significant downregulation of Rbm20 expression. Our findings demonstrate the importance of the skeletal muscle circadian clock in maintaining titin isoform through regulation of RBM20 expression. Because circadian rhythm disruption is a feature of many chronic diseases, our results highlight a novel pathway that could be targeted to maintain skeletal muscle structure and function in a range of pathologies.
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Affiliation(s)
- Lance A Riley
- Department of Physiology and Functional Genomics, University of FloridaGainesvilleUnited States,Myology Institute, University of FloridaGainesvilleUnited States
| | - Xiping Zhang
- Department of Physiology and Functional Genomics, University of FloridaGainesvilleUnited States,Myology Institute, University of FloridaGainesvilleUnited States
| | - Collin M Douglas
- Department of Physiology and Functional Genomics, University of FloridaGainesvilleUnited States,Myology Institute, University of FloridaGainesvilleUnited States
| | - Joseph M Mijares
- Department of Physiology and Functional Genomics, University of FloridaGainesvilleUnited States,Myology Institute, University of FloridaGainesvilleUnited States
| | - David W Hammers
- Myology Institute, University of FloridaGainesvilleUnited States,Department of Pharmacology and Therapeutics, University of FloridaGainesvilleUnited States
| | - Christopher A Wolff
- Department of Physiology and Functional Genomics, University of FloridaGainesvilleUnited States,Myology Institute, University of FloridaGainesvilleUnited States
| | - Neil B Wood
- Department of Molecular Physiology and Biophysics, University of VermontBurlingtonUnited States
| | - Hailey R Olafson
- Department of Molecular Genetics of Microbiology, Center for Neurogenetics, University of FloridaGainesvilleUnited States
| | - Ping Du
- Department of Physiology and Functional Genomics, University of FloridaGainesvilleUnited States
| | - Siegfried Labeit
- Medical Faculty Mannheim, University of HeidelbergMannheimGermany
| | - Michael J Previs
- Department of Molecular Physiology and Biophysics, University of VermontBurlingtonUnited States
| | - Eric T Wang
- Myology Institute, University of FloridaGainesvilleUnited States,Department of Molecular Genetics of Microbiology, Center for Neurogenetics, University of FloridaGainesvilleUnited States
| | - Karyn A Esser
- Department of Physiology and Functional Genomics, University of FloridaGainesvilleUnited States,Myology Institute, University of FloridaGainesvilleUnited States
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19
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Helms AS, Thompson AD, Day SM. Translation of New and Emerging Therapies for Genetic Cardiomyopathies. JACC Basic Transl Sci 2022; 7:70-83. [PMID: 35128211 PMCID: PMC8807730 DOI: 10.1016/j.jacbts.2021.07.012] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Revised: 07/29/2021] [Accepted: 07/29/2021] [Indexed: 11/05/2022]
Abstract
The primary etiology of a diverse range of cardiomyopathies is now understood to be genetic, creating a new paradigm for targeting treatments on the basis of the underlying molecular cause. This review provides a genetic and etiologic context for the traditional clinical classifications of cardiomyopathy, including molecular subtypes that may exhibit differential responses to existing or emerging treatments. The authors describe several emerging cardiomyopathy treatments, including gene therapy, direct targeting of myofilament function, protein quality control, metabolism, and others. The authors discuss advantages and disadvantages of these approaches and indicate areas of high potential for short- and longer term efficacy.
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Key Words
- AAV, adeno-associated virus
- ACM, arrhythmogenic cardiomyopathy
- ARVC, arrhythmogenic right ventricular cardiomyopathy
- ATPase, adenosine triphosphatase
- DCM, dilated cardiomyopathy
- DMD, Duchenne muscular dystrophy
- DNA, DNA
- DSP, desmoplakin
- FDA, U.S. Food and Drug Administration
- GRT, gene replacement therapy
- GST, gene silencing therapy
- HCM, hypertrophic cardiomyopathy
- HR, homologous recombination
- LNP, lipid nanoparticle
- LVOT, left ventricular outflow tract
- RNA, RNA
- TTR, transthyretin
- arrhythmogenic cardiomyopathy
- dilated cardiomyopathy
- genetics
- hypertrophic cardiomyopathy
- therapeutics
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Affiliation(s)
- Adam S. Helms
- Department of Medicine, University of Michigan, Ann Arbor, Michigan, USA
| | - Andrea D. Thompson
- Department of Medicine, University of Michigan, Ann Arbor, Michigan, USA
| | - Sharlene M. Day
- Department of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
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20
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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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21
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Tsan YC, DePalma SJ, Zhao YT, Capilnasiu A, Wu YW, Elder B, Panse I, Ufford K, Matera DL, Friedline S, O'Leary TS, Wubshet N, Ho KKY, Previs MJ, Nordsletten D, Isom LL, Baker BM, Liu AP, Helms AS. Physiologic biomechanics enhance reproducible contractile development in a stem cell derived cardiac muscle platform. Nat Commun 2021; 12:6167. [PMID: 34697315 PMCID: PMC8546060 DOI: 10.1038/s41467-021-26496-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Accepted: 10/05/2021] [Indexed: 12/29/2022] Open
Abstract
Human pluripotent stem cell-derived cardiomyocytes (hPSC-CMs) allow investigations in a human cardiac model system, but disorganized mechanics and immaturity of hPSC-CMs on standard two-dimensional surfaces have been hurdles. Here, we developed a platform of micron-scale cardiac muscle bundles to control biomechanics in arrays of thousands of purified, independently contracting cardiac muscle strips on two-dimensional elastomer substrates with far greater throughput than single cell methods. By defining geometry and workload in this reductionist platform, we show that myofibrillar alignment and auxotonic contractions at physiologic workload drive maturation of contractile function, calcium handling, and electrophysiology. Using transcriptomics, reporter hPSC-CMs, and quantitative immunofluorescence, these cardiac muscle bundles can be used to parse orthogonal cues in early development, including contractile force, calcium load, and metabolic signals. Additionally, the resultant organized biomechanics facilitates automated extraction of contractile kinetics from brightfield microscopy imaging, increasing the accessibility, reproducibility, and throughput of pharmacologic testing and cardiomyopathy disease modeling. Investigations of human cardiac disease involving human pluripotent stem cell-derived cardiomyocytes are limited by the disorganized presentation of biomechanical cues resulting in cell immaturity. Here the authors develop a platform of micron-scale 2D cardiac muscle bundles to precisely deliver physiologic cues, improving reproducibility and throughput.
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Affiliation(s)
- Yao-Chang Tsan
- Division of Cardiovascular Medicine, University of Michigan, Ann Arbor, MI, USA.,Department of Human Genetics, University of Michigan, Ann Arbor, MI, USA
| | - Samuel J DePalma
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA
| | - Yan-Ting Zhao
- Department of Pharmacology, University of Michigan, Ann Arbor, MI, USA
| | - Adela Capilnasiu
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA
| | - Yu-Wei Wu
- Institute of Molecular Biology, Academia Sinica, NanKang, Taipei, Taiwan
| | - Brynn Elder
- Division of Cardiovascular Medicine, University of Michigan, Ann Arbor, MI, USA
| | - Isabella Panse
- Division of Cardiovascular Medicine, University of Michigan, Ann Arbor, MI, USA
| | - Kathryn Ufford
- Division of Cardiovascular Medicine, University of Michigan, Ann Arbor, MI, USA
| | - Daniel L Matera
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA
| | - Sabrina Friedline
- Division of Cardiovascular Medicine, University of Michigan, Ann Arbor, MI, USA
| | - Thomas S O'Leary
- Molecular Physiology and Biophysics, University of Vermont, Burlington, VT, USA
| | - Nadab Wubshet
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI, USA
| | - Kenneth K Y Ho
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI, USA
| | - Michael J Previs
- Molecular Physiology and Biophysics, University of Vermont, Burlington, VT, USA
| | - David Nordsletten
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA.,Department of Cardiovascular Surgery, University of Michigan, Ann Arbor, MI, USA
| | - Lori L Isom
- Department of Pharmacology, University of Michigan, Ann Arbor, MI, USA.,Department of Neurology, University of Michigan, Ann Arbor, MI, USA.,Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI, USA
| | - Brendon M Baker
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA
| | - Allen P Liu
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA.,Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI, USA.,Department of Biophysics, University of Michigan, Ann Arbor, MI, USA
| | - Adam S Helms
- Division of Cardiovascular Medicine, University of Michigan, Ann Arbor, MI, USA.
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22
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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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23
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Suay-Corredera C, Pricolo MR, Herrero-Galán E, Velázquez-Carreras D, Sánchez-Ortiz D, García-Giustiniani D, Delgado J, Galano-Frutos JJ, García-Cebollada H, Vilches S, Domínguez F, Molina MS, Barriales-Villa R, Frisso G, Sancho J, Serrano L, García-Pavía P, Monserrat L, Alegre-Cebollada J. Protein haploinsufficiency drivers identify MYBPC3 variants that cause hypertrophic cardiomyopathy. J Biol Chem 2021; 297:100854. [PMID: 34097875 PMCID: PMC8260873 DOI: 10.1016/j.jbc.2021.100854] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Revised: 05/21/2021] [Accepted: 06/03/2021] [Indexed: 02/06/2023] Open
Abstract
Hypertrophic cardiomyopathy (HCM) is the most common inherited cardiac disease. Variants in MYBPC3, the gene encoding cardiac myosin-binding protein C (cMyBP-C), are the leading cause of HCM. However, the pathogenicity status of hundreds of MYBPC3 variants found in patients remains unknown, as a consequence of our incomplete understanding of the pathomechanisms triggered by HCM-causing variants. Here, we examined 44 nontruncating MYBPC3 variants that we classified as HCM-linked or nonpathogenic according to cosegregation and population genetics criteria. We found that around half of the HCM-linked variants showed alterations in RNA splicing or protein stability, both of which can lead to cMyBP-C haploinsufficiency. These protein haploinsufficiency drivers associated with HCM pathogenicity with 100% and 94% specificity, respectively. Furthermore, we uncovered that 11% of nontruncating MYBPC3 variants currently classified as of uncertain significance in ClinVar induced one of these molecular phenotypes. Our strategy, which can be applied to other conditions induced by protein loss of function, supports the idea that cMyBP-C haploinsufficiency is a fundamental pathomechanism in HCM.
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Affiliation(s)
| | - Maria Rosaria Pricolo
- Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain; Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Università di Napoli Federico II, Naples, Italy
| | | | | | | | | | - Javier Delgado
- EMBL/CRG Systems Biology Research Unit, Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Juan José Galano-Frutos
- Departamento de Bioquímica y Biología Molecular y Celular, Facultad de Ciencias, Universidad de Zaragoza, Zaragoza, Spain; Biocomputation and Complex Systems Physics Institute (BIFI). Joint Units BIFI-IQFR (CSIC) and GBs-CSIC, Universidad de Zaragoza, Zaragoza, Spain
| | - Helena García-Cebollada
- Departamento de Bioquímica y Biología Molecular y Celular, Facultad de Ciencias, Universidad de Zaragoza, Zaragoza, Spain; Biocomputation and Complex Systems Physics Institute (BIFI). Joint Units BIFI-IQFR (CSIC) and GBs-CSIC, Universidad de Zaragoza, Zaragoza, Spain
| | - Silvia Vilches
- Heart Failure and Inherited Cardiac Diseases Unit. Department of Cardiology. Hospital Universitario Puerta de Hierro, Madrid, Spain; European Reference Network for Rare and Low Prevalence Complex Diseases of the Heart (ERN GUARD-HEART), Madrid, Spain
| | - Fernando Domínguez
- Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain; Heart Failure and Inherited Cardiac Diseases Unit. Department of Cardiology. Hospital Universitario Puerta de Hierro, Madrid, Spain; European Reference Network for Rare and Low Prevalence Complex Diseases of the Heart (ERN GUARD-HEART), Madrid, Spain; Centro de Investigación Biomédica en Red en Enfermedades Cardiovasculares (CIBERCV), Madrid, Spain
| | - María Sabater Molina
- European Reference Network for Rare and Low Prevalence Complex Diseases of the Heart (ERN GUARD-HEART), Madrid, Spain; Hospital C. Universitario Virgen de la Arrixaca, El Palmar, Murcia, Spain
| | - Roberto Barriales-Villa
- Centro de Investigación Biomédica en Red en Enfermedades Cardiovasculares (CIBERCV), Madrid, Spain; Unidad de Cardiopatías Familiares, Instituto de Investigación Biomédica de A Coruña (INIBIC), Complexo Hospitalario Universitario de A Coruña, Servizo Galego de Saúde (SERGAS), Universidade da Coruña, A Coruña, Spain
| | - Giulia Frisso
- Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Università di Napoli Federico II, Naples, Italy; CEINGE Biotecnologie Avanzate, scarl, Naples, Italy
| | - Javier Sancho
- Departamento de Bioquímica y Biología Molecular y Celular, Facultad de Ciencias, Universidad de Zaragoza, Zaragoza, Spain; Biocomputation and Complex Systems Physics Institute (BIFI). Joint Units BIFI-IQFR (CSIC) and GBs-CSIC, Universidad de Zaragoza, Zaragoza, Spain; Aragon Health Research Institute (IIS Aragón), Zaragoza, Spain
| | - Luis Serrano
- EMBL/CRG Systems Biology Research Unit, Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Barcelona, Spain; Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain; Universitat Pompeu Fabra (UPF), Barcelona, Spain
| | - Pablo García-Pavía
- Heart Failure and Inherited Cardiac Diseases Unit. Department of Cardiology. Hospital Universitario Puerta de Hierro, Madrid, Spain; European Reference Network for Rare and Low Prevalence Complex Diseases of the Heart (ERN GUARD-HEART), Madrid, Spain; Centro de Investigación Biomédica en Red en Enfermedades Cardiovasculares (CIBERCV), Madrid, Spain; Universidad Francisco de Vitoria (UFV), Pozuelo de Alarcón, Madrid, Spain
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24
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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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25
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Rasicci DV, Kirkland O, Moonschi FH, Wood NB, Szczesna-Cordary D, Previs MJ, Wenk JF, Campbell KS, Yengo CM. Impact of regulatory light chain mutation K104E on the ATPase and motor properties of cardiac myosin. J Gen Physiol 2021; 153:212025. [PMID: 33891674 PMCID: PMC8077168 DOI: 10.1085/jgp.202012811] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Accepted: 03/19/2021] [Indexed: 12/11/2022] Open
Abstract
Mutations in the cardiac myosin regulatory light chain (RLC, MYL2 gene) are known to cause inherited cardiomyopathies with variable phenotypes. In this study, we investigated the impact of a mutation in the RLC (K104E) that is associated with hypertrophic cardiomyopathy (HCM). Previously in a mouse model of K104E, older animals were found to develop cardiac hypertrophy, fibrosis, and diastolic dysfunction, suggesting a slow development of HCM. However, variable penetrance of the mutation in human populations suggests that the impact of K104E may be subtle. Therefore, we generated human cardiac myosin subfragment-1 (M2β-S1) and exchanged on either the wild type (WT) or K104E human ventricular RLC in order to assess the impact of the mutation on the mechanochemical properties of cardiac myosin. The maximum actin-activated ATPase activity and actin sliding velocities in the in vitro motility assay were similar in M2β-S1 WT and K104E, as were the detachment kinetic parameters, including the rate of ATP-induced dissociation and the ADP release rate constant. We also examined the mechanical performance of α-cardiac myosin extracted from transgenic (Tg) mice expressing human wild type RLC (Tg WT) or mutant RLC (Tg K104E). We found that α-cardiac myosin from Tg K104E animals demonstrated enhanced actin sliding velocities in the motility assay compared with its Tg WT counterpart. Furthermore, the degree of incorporation of the mutant RLC into α-cardiac myosin in the transgenic animals was significantly reduced compared with wild type. Therefore, we conclude that the impact of the K104E mutation depends on either the length or the isoform of the myosin heavy chain backbone and that the mutation may disrupt RLC interactions with the myosin lever arm domain.
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Affiliation(s)
- David V Rasicci
- Pennsylvania State University College of Medicine, Hershey, PA
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26
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Arnold ME, Dostmann WR, Martin J, Previs MJ, Palmer B, LeWinter M, Meyer M. SERCA2a-phospholamban interaction monitored by an interposed circularly permutated green fluorescent protein. Am J Physiol Heart Circ Physiol 2021; 320:H2188-H2200. [PMID: 33861144 DOI: 10.1152/ajpheart.00858.2020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The interaction of phospholamban (PLB) and the sarcoplasmic reticulum Ca2+-ATPase (SERCA2a) is a key regulator of cardiac contractility and a therapeutic target in heart failure (HF). PLB-mediated increases in SERCA2a activity improve cardiac function and HF. Clinically, this mechanism can only be exploited by a general activation of the proteinkinase A (PKA), which is associated with side effects and adverse clinical outcomes. A selective interference of the PLB-SERCA2a interaction is desirable but will require novel tools that allow for an integrated assessment of this interaction under both physiological and pathophysiological conditions. A circularly permutated green fluorescent protein (cpGFP) was interposed between SERCA2a and PLB to result into a single SERCA2a-cpGFP-PLB recombinant protein (SGP). Expression, phosphorylation, fluorescence, and function of SGP were evaluated. Expression of SGP-cDNA results in a functional recombinant protein at the predicted molecular weight. The PLB domain of SGP retains its ability to polymerize and can be phosphorylated by PKA activation. This increases the fluorescent yield of SGP by between 10% and 165% depending on cell line and conditions. In conclusion, a single recombinant fusion protein that combines SERCA2a, a circularly permutated green fluorescent protein, and PLB can be expressed in cells and can be phosphorylated at the PLB domain that markedly increases the fluorescence yield. SGP is a novel cellular SERCA2a-PLB interaction monitor.NEW & NOTEWORTHY This study describes the design and characterization of a novel biosensor that can visualize the interaction of SERCA2a and phospholamban (PLB). The biosensor combines SERCA2a, a circularly permutated green fluorescent protein, and PLB into one recombinant protein (SGP). Proteinkinase A activation results in phosphorylation of the PLB domain and is associated with a marked increase in the fluorescence yield to allow for real-time monitoring of the SERCA2a and PLB interaction in cells.
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Affiliation(s)
- Maren E Arnold
- Department of Medicine and Molecular Physiology and Biophysics, University of Vermont Larner College of Medicine, Burlington, Vermont.,Institute of Experimental and Clinical Pharmacology und Toxicology, Faculty of Medicine, Albert-Ludwigs-University Freiburg, Freiburg, Germany
| | - Wolfgang R Dostmann
- Department of Pharmacology, University of Vermont Larner College of Medicine, Burlington, Vermont
| | - Jody Martin
- Department of Pharmacology, School of Medicine, Cardiovascular Research Institute, University of California, Davis, California
| | - Michael J Previs
- Department of Medicine and Molecular Physiology and Biophysics, University of Vermont Larner College of Medicine, Burlington, Vermont
| | - Bradley Palmer
- Department of Medicine and Molecular Physiology and Biophysics, University of Vermont Larner College of Medicine, Burlington, Vermont
| | - Martin LeWinter
- Department of Medicine and Molecular Physiology and Biophysics, University of Vermont Larner College of Medicine, Burlington, Vermont
| | - Markus Meyer
- Department of Medicine, Lillehei Heart Institute, University of Minnesota College of Medicine, Minneapolis, Minnesota
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27
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Computational prediction of protein subdomain stability in MYBPC3 enables clinical risk stratification in hypertrophic cardiomyopathy and enhances variant interpretation. Genet Med 2021; 23:1281-1287. [PMID: 33782553 PMCID: PMC8257482 DOI: 10.1038/s41436-021-01134-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Revised: 02/15/2021] [Accepted: 02/16/2021] [Indexed: 12/13/2022] Open
Abstract
Purpose Variants in MYBPC3 causing loss of function are the most common cause of hypertrophic cardiomyopathy (HCM). However, a substantial number of patients carry missense variants of uncertain significance (VUS) in MYBPC3. We hypothesize that a structural-based algorithm, STRUM, which estimates the effect of missense variants on protein folding, will identify a subgroup of HCM patients with a MYBPC3 VUS associated with increased clinical risk. Methods Among 7,963 patients in the multicenter Sarcomeric Human Cardiomyopathy Registry (SHaRe), 120 unique missense VUS in MYBPC3 were identified. Variants were evaluated for their effect on subdomain folding and a stratified time-to-event analysis for an overall composite endpoint (first occurrence of ventricular arrhythmia, heart failure, all-cause mortality, atrial fibrillation, and stroke) was performed for patients with HCM and a MYBPC3 missense VUS. Results We demonstrated that patients carrying a MYBPC3 VUS predicted to cause subdomain misfolding (STRUM+, ΔΔG ≤ −1.2 kcal/mol) exhibited a higher rate of adverse events compared with those with a STRUM- VUS (hazard ratio = 2.29, P = 0.0282). In silico saturation mutagenesis of MYBPC3 identified 4,943/23,427 (21%) missense variants that were predicted to cause subdomain misfolding. Conclusion STRUM identifies patients with HCM and a MYBPC3 VUS who may be at higher clinical risk and provides supportive evidence for pathogenicity.
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28
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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: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [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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29
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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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30
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Bunch TA, Lepak VC, Bortz KM, Colson BA. A high-throughput fluorescence lifetime-based assay to detect binding of myosin-binding protein C to F-actin. J Gen Physiol 2021; 153:e202012707. [PMID: 33600558 PMCID: PMC7898471 DOI: 10.1085/jgp.202012707] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Accepted: 01/12/2021] [Indexed: 12/20/2022] Open
Abstract
Binding properties of actin-binding proteins are typically evaluated by cosedimentation assays. However, this method is time-consuming, involves multiple steps, and has a limited throughput. These shortcomings preclude its use in screening for drugs that modulate actin-binding proteins relevant to human disease. To develop a simple, quantitative, and scalable F-actin-binding assay, we attached fluorescent probes to actin's Cys-374 and assessed changes in fluorescence lifetime upon binding to the N-terminal region (domains C0-C2) of human cardiac myosin-binding protein C (cMyBP-C). The lifetime of all five probes tested decreased upon incubation with cMyBP-C C0-C2, as measured by time-resolved fluorescence (TR-F), with IAEDANS being the most sensitive probe that yielded the smallest errors. The TR-F assay was compared with cosedimentation to evaluate in vitro changes in binding to actin and actin-tropomyosin arising from cMyBP-C mutations associated with hypertrophic cardiomyopathy (HCM) and tropomyosin binding. Lifetime changes of labeled actin with added C0-C2 were consistent with cosedimentation results. The HCM mutation L352P was confirmed to enhance actin binding, whereas PKA phosphorylation reduced binding. The HCM mutation R282W, predicted to disrupt a PKA recognition sequence, led to deficits in C0-C2 phosphorylation and altered binding. Lastly, C0-C2 binding was found to be enhanced by tropomyosin and binding capacity to be altered by mutations in a tropomyosin-binding region. These findings suggest that the TR-F assay is suitable for rapidly and accurately determining quantitative binding and for screening physiological conditions and compounds that affect cMyBP-C binding to F-actin for therapeutic discovery.
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Affiliation(s)
| | | | | | - Brett A. Colson
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ
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31
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Jin J, Lu L, Chen J, Wang K, Han J, Xue S, Weng G. Generation of an induced pluripotential stem cell (iPSC) line from a patient with hypertrophic cardiomyopathy carrying myosin binding protein C (MYBPC3) c.3369-3370 insC mutation. Stem Cell Res 2020; 50:102144. [PMID: 33388705 DOI: 10.1016/j.scr.2020.102144] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Revised: 11/27/2020] [Accepted: 12/22/2020] [Indexed: 11/29/2022] Open
Abstract
Hypertrophic cardiomyopathy (HCM) is a disease in which the heart muscle becomes abnormally thick making it difficult for the heart to pump blood. In this study an induced pluripotent stem cells (iPSC) line was derived from peripheral blood mononuclear cells of a 62-year-old male hypertrophic cardiomyopathy (HCM) patient with the mutation of heterozygous pathogenic myosin binding protein C (MYBPC3) c.3369-3370 insC using an episomal method. The generated iPSC line presented normal 46, XY male karyotypes, expressed pluripotent markers and could spontaneously differentiate into triblast cells. This HCM-specific iPSC line could act as a useful tool for studying and modeling hypertrophic cardiomyopathy.
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Affiliation(s)
- Jingjun Jin
- Translational Medicine Research Center, Fujian Academy of Medical Sciences, Fuzhou 350001, China.
| | - Lihong Lu
- Shengli Clinical Medical College of Fujian Medical University, Fuzhou 350001, China
| | - Jinyan Chen
- Translational Medicine Research Center, Fujian Academy of Medical Sciences, Fuzhou 350001, China
| | - Kun Wang
- Department of Immunology, Fujian Academy of Medical Sciences, Fuzhou 350001, China
| | - Junyong Han
- Department of Immunology, Fujian Academy of Medical Sciences, Fuzhou 350001, China
| | - Shijie Xue
- Department of Immunology, Fujian Academy of Medical Sciences, Fuzhou 350001, China
| | - Guoxing Weng
- Translational Medicine Research Center, Fujian Academy of Medical Sciences, Fuzhou 350001, China; Shengli Clinical Medical College of Fujian Medical University, Fuzhou 350001, China.
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32
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Downes DP, Kasumov T, Daurio NA, Wood NB, Previs MJ, Sheth PR, McLaren DG, Previs SF. Isotope Fractionation during Gas Chromatography Can Enhance Mass Spectrometry-Based Measures of 2H-Labeling of Small Molecules. Metabolites 2020; 10:E474. [PMID: 33233825 PMCID: PMC7699861 DOI: 10.3390/metabo10110474] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Revised: 11/06/2020] [Accepted: 11/12/2020] [Indexed: 11/16/2022] Open
Abstract
Stable isotope tracers can be used to quantify the activity of metabolic pathways. Specifically, 2H-water is quite versatile, and its incorporation into various products can enable measurements of carbohydrate, lipid, protein and nucleic acid kinetics. However, since there are limits on how much 2H-water can be administered and since some metabolic processes may be slow, it is possible that one may be challenged with measuring small changes in isotopic enrichment. We demonstrate an advantage of the isotope fractionation that occurs during gas chromatography, namely, setting tightly bounded integration regions yields a powerful approach for determining isotope ratios. We determined how the degree of isotope fractionation, chromatographic peak width and mass spectrometer dwell time can increase the apparent isotope labeling. Relatively simple changes in the logic surrounding data acquisition and processing can enhance gas chromatography-mass spectrometry measures of low levels of 2H-labeling, this is especially useful when asymmetrical peaks are recorded at low signal:background. Although we have largely focused attention on alanine (which is of interest in studies of protein synthesis), it should be possible to extend the concepts to other analytes and/or hardware configurations.
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Affiliation(s)
- Daniel P. Downes
- Department of Chemistry, Merck & Co., Inc., Kenilworth, NJ 07033, USA; (D.P.D.); (N.A.D.); (P.R.S.); (D.G.M.)
| | - Takhar Kasumov
- Department of Pharmaceutical Sciences, Northeast Ohio Medical University, Rootstown, OH 44272, USA;
| | - Natalie A. Daurio
- Department of Chemistry, Merck & Co., Inc., Kenilworth, NJ 07033, USA; (D.P.D.); (N.A.D.); (P.R.S.); (D.G.M.)
| | - Neil B. Wood
- Department of Molecular Physiology & Biophysics, University of Vermont, Burlington, VT 05405, USA; (N.B.W.); (M.J.P.)
| | - Michael J. Previs
- Department of Molecular Physiology & Biophysics, University of Vermont, Burlington, VT 05405, USA; (N.B.W.); (M.J.P.)
| | - Payal R. Sheth
- Department of Chemistry, Merck & Co., Inc., Kenilworth, NJ 07033, USA; (D.P.D.); (N.A.D.); (P.R.S.); (D.G.M.)
| | - David G. McLaren
- Department of Chemistry, Merck & Co., Inc., Kenilworth, NJ 07033, USA; (D.P.D.); (N.A.D.); (P.R.S.); (D.G.M.)
| | - Stephen F. Previs
- Department of Chemistry, Merck & Co., Inc., Kenilworth, NJ 07033, USA; (D.P.D.); (N.A.D.); (P.R.S.); (D.G.M.)
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33
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Carrier L. Targeting the population for gene therapy with MYBPC3. J Mol Cell Cardiol 2020; 150:101-108. [PMID: 33049255 DOI: 10.1016/j.yjmcc.2020.10.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Revised: 09/02/2020] [Accepted: 10/05/2020] [Indexed: 12/14/2022]
Abstract
Hypertrophic cardiomyopathy (HCM) is the most prevalent inherited myocardial disease characterized by unexplained left ventricular hypertrophy, diastolic dysfunction and myocardial disarray. Clinical heterogeneity is wide, ranging from asymptomatic individuals to heart failure, arrhythmias and sudden death. HCM is often caused by mutations in genes encoding components of the sarcomere. Among them, MYBPC3, encoding cardiac myosin-myosin binding protein C is the most frequently mutated gene. Three quarter of pathogenic or likely pathogenic mutations in MYBPC3 are truncating and the resulting protein was not detected in HCM myectomy samples. The overall prognosis of the patients is excellent if managed with contemporary therapy, but still remains a significant disease-related health burden, and carriers with double heterozygous, compound heterozygous and homozygous mutations often display a more severe clinical phenotype than single heterozygotes. We propose these individuals as a good target population for MYBPC3 gene therapy.
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Affiliation(s)
- Lucie Carrier
- Institute of Experimental Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, Hamburg, Germany; DZHK (German Centre for Cardiovascular Research), partner site Hamburg, Kiel, Lübeck, Germany.
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34
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Li J, Mamidi R, Doh CY, Holmes JB, Bharambe N, Ramachandran R, Stelzer JE. AAV9 gene transfer of cMyBPC N-terminal domains ameliorates cardiomyopathy in cMyBPC-deficient mice. JCI Insight 2020; 5:130182. [PMID: 32750038 PMCID: PMC7526450 DOI: 10.1172/jci.insight.130182] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Accepted: 07/29/2020] [Indexed: 01/05/2023] Open
Abstract
Decreased cardiac myosin-binding protein C (cMyBPC) expression due to inheritable mutations is thought to contribute to the hypertrophic cardiomyopathy (HCM) phenotype, suggesting that increasing cMyBPC content is of therapeutic benefit. In vitro assays show that cMyBPC N-terminal domains (NTDs) contain structural elements necessary and sufficient to modulate actomyosin interactions, but it is unknown if they can regulate in vivo myocardial function. To test whether NTDs can recapitulate the effects of full-length (FL) cMyBPC in rescuing cardiac function in a cMyBPC-null mouse model of HCM, we assessed the efficacy of AAV9 gene transfer of a cMyBPC NTD that contained domains C0C2 and compared its therapeutic potential with AAV9-FL gene replacement. AAV9 vectors were administered systemically at neonatal day 1, when early-onset disease phenotypes begin to manifest. A comprehensive analysis of in vivo and in vitro function was performed following cMyBPC gene transfer. Our results show that a systemic injection of AAV9-C0C2 significantly improved cardiac function (e.g., 52.24 ± 1.69 ejection fraction in the C0C2-treated group compared with 40.07 ± 1.97 in the control cMyBPC–/– group, P < 0.05) and reduced the histopathologic signs of cardiomyopathy. Furthermore, C0C2 significantly slowed and normalized the accelerated cross-bridge kinetics found in cMyBPC–/– control myocardium, as evidenced by a 32.41% decrease in the rate of cross-bridge detachment (krel). Results indicate that C0C2 can rescue biomechanical defects of cMyBPC deficiency and that the NTD may be a target region for therapeutic myofilament kinetic manipulation. Cardiac function improves following AAV9-mediated delivery of the C0C2 domains of cardiac myosin-binding protein C in a mouse model of hypertrophic cardiomyopathy.
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35
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Helms AS, Thompson AD, Glazier AA, Hafeez N, Kabani S, Rodriguez J, Yob JM, Woolcock H, Mazzarotto F, Lakdawala NK, Wittekind SG, Pereira AC, Jacoby DL, Colan SD, Ashley EA, Saberi S, Ware JS, Ingles J, Semsarian C, Michels M, Olivotto I, Ho CY, Day SM. Spatial and Functional Distribution of MYBPC3 Pathogenic Variants and Clinical Outcomes in Patients With Hypertrophic Cardiomyopathy. CIRCULATION-GENOMIC AND PRECISION MEDICINE 2020; 13:396-405. [PMID: 32841044 PMCID: PMC7676622 DOI: 10.1161/circgen.120.002929] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Supplemental Digital Content is available in the text. Pathogenic variants in MYBPC3, encoding cardiac MyBP-C (myosin binding protein C), are the most common cause of familial hypertrophic cardiomyopathy. A large number of unique MYBPC3 variants and relatively small genotyped hypertrophic cardiomyopathy cohorts have precluded detailed genotype-phenotype correlations.
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Affiliation(s)
- Adam S Helms
- Cardiovascular Medicine (A.S.H., A.D.T., N.H., S.K., J.R., J.M.Y., H.W., S.S.), University of Michigan, Ann Arbor
| | - Andrea D Thompson
- Cardiovascular Medicine (A.S.H., A.D.T., N.H., S.K., J.R., J.M.Y., H.W., S.S.), University of Michigan, Ann Arbor
| | - Amelia A Glazier
- Molecular & Integrative Physiology (A.A.G.), University of Michigan, Ann Arbor
| | - Neha Hafeez
- Cardiovascular Medicine (A.S.H., A.D.T., N.H., S.K., J.R., J.M.Y., H.W., S.S.), University of Michigan, Ann Arbor
| | - Samat Kabani
- Cardiovascular Medicine (A.S.H., A.D.T., N.H., S.K., J.R., J.M.Y., H.W., S.S.), University of Michigan, Ann Arbor
| | - Juliani Rodriguez
- Cardiovascular Medicine (A.S.H., A.D.T., N.H., S.K., J.R., J.M.Y., H.W., S.S.), University of Michigan, Ann Arbor
| | - Jaime M Yob
- Cardiovascular Medicine (A.S.H., A.D.T., N.H., S.K., J.R., J.M.Y., H.W., S.S.), University of Michigan, Ann Arbor
| | - Helen Woolcock
- Cardiovascular Medicine (A.S.H., A.D.T., N.H., S.K., J.R., J.M.Y., H.W., S.S.), University of Michigan, Ann Arbor
| | - Francesco Mazzarotto
- Department of Experimental & Clinical Medicine, University of Florence, Italy (F.M., I.O.).,National Heart & Lung Institute & Royal Brompton Cardiovascular Research Center, Imperial College London, United Kingdom (F.M., J.S.W.)
| | - Neal K Lakdawala
- Cardiovascular Medicine, Brigham & Women's Hospital, Harvard Medical School, Boston, MA (N.K.L., C.Y.H.)
| | - Samuel G Wittekind
- Cincinnati Children's Hospital Medical Center, Heart Institute, Cincinnati, OH (S.G.W.)
| | - Alexandre C Pereira
- Heart Institute (InCor), University of Sao Paolo Medical School, Brazil (A.C.P.)
| | - Daniel L Jacoby
- Cardiovascular Medicine, Yale University, New Haven, CT (D.L.J.)
| | - Steven D Colan
- Department of Cardiology, Boston Children's Hospital, MA (S.D.C.)
| | - Euan A Ashley
- Center for Inherited Heart Disease, Stanford University, CA (E.A.A.)
| | - Sara Saberi
- Cardiovascular Medicine (A.S.H., A.D.T., N.H., S.K., J.R., J.M.Y., H.W., S.S.), University of Michigan, Ann Arbor
| | | | - Jodie Ingles
- Agnes Ginges Centre for Molecular Cardiology at Centenary Institute, The University of Sydney, Australia (J.I., C.S.)
| | - Christopher Semsarian
- Agnes Ginges Centre for Molecular Cardiology at Centenary Institute, The University of Sydney, Australia (J.I., C.S.)
| | - Michelle Michels
- Department of Cardiology, Erasmus Medical Center, Rotterdam, the Netherlands (M.M.)
| | - Iacopo Olivotto
- Department of Experimental & Clinical Medicine, University of Florence, Italy (F.M., I.O.).,Cardiomyopathy Unit, Careggi University Hospital, Florence, Italy (I.O.)
| | - Carolyn Y Ho
- Cardiovascular Medicine, Brigham & Women's Hospital, Harvard Medical School, Boston, MA (N.K.L., C.Y.H.)
| | - Sharlene M Day
- Cardiovascular Medicine, University of Pennsylvania, Philadelphia (S.M.D.)
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36
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Daneshparvar N, Taylor DW, O'Leary TS, Rahmani H, Abbasiyeganeh F, Previs MJ, Taylor KA. CryoEM structure of Drosophila flight muscle thick filaments at 7 Å resolution. Life Sci Alliance 2020; 3:3/8/e202000823. [PMID: 32718994 PMCID: PMC7391215 DOI: 10.26508/lsa.202000823] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Revised: 06/30/2020] [Accepted: 06/30/2020] [Indexed: 11/24/2022] Open
Abstract
Striated muscle thick filaments are composed of myosin II and several non-myosin proteins. Myosin II's long α-helical coiled-coil tail forms the dense protein backbone of filaments, whereas its N-terminal globular head containing the catalytic and actin-binding activities extends outward from the backbone. Here, we report the structure of thick filaments of the flight muscle of the fruit fly Drosophila melanogaster at 7 Å resolution. Its myosin tails are arranged in curved molecular crystalline layers identical to flight muscles of the giant water bug Lethocerus indicus Four non-myosin densities are observed, three of which correspond to ones found in Lethocerus; one new density, possibly stretchin-mlck, is found on the backbone outer surface. Surprisingly, the myosin heads are disordered rather than ordered along the filament backbone. Our results show striking myosin tail similarity within flight muscle filaments of two insect orders separated by several hundred million years of evolution.
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Affiliation(s)
- Nadia Daneshparvar
- Department of Physics, Florida State University, Tallahassee, FL, USA.,Institute of Molecular Biophysics, Florida State University, Tallahassee, FL, USA
| | - Dianne W Taylor
- Institute of Molecular Biophysics, Florida State University, Tallahassee, FL, USA
| | - Thomas S O'Leary
- Department of Molecular Physiology & Biophysics, University of Vermont College of Medicine, Burlington, VT, USA
| | - Hamidreza Rahmani
- Department of Physics, Florida State University, Tallahassee, FL, USA.,Institute of Molecular Biophysics, Florida State University, Tallahassee, FL, USA
| | | | - Michael J Previs
- Department of Molecular Physiology & Biophysics, University of Vermont College of Medicine, Burlington, VT, USA
| | - Kenneth A Taylor
- Institute of Molecular Biophysics, Florida State University, Tallahassee, FL, USA
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37
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Popular three-dimensional models: Advantages for cancer, Alzheimer's and cardiovascular diseases. Tissue Cell 2020; 65:101367. [PMID: 32746982 DOI: 10.1016/j.tice.2020.101367] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Revised: 04/08/2020] [Accepted: 04/09/2020] [Indexed: 11/21/2022]
Abstract
The increasing prevalence of non-communicable diseases, namely cancer, Alzheimer's (AD) and cardiovascular diseases (CVDs), worldwide continues to be a major health burden. Research attempts have been made to understand the pathophysiology and develop effective therapeutic agents for these diseases using conventional in vitro and ex vivo models. Due to the complexity of human disease mechanisms, often these models fail to recapitulate clinically relevant pathologies. As such, interests are arising in the exploration of three-dimensional (3D) in-vitro models, which create an artificial environment to closely mimic in vivo human conditions. Several studies have developed 3D models for cancer, AD and CVD research which can greatly improve the understanding of biological mechanisms and mirror clinical drug activities. Thus, 3D cultures may provide new in-vitro models that recapitulate the architecture and biological mechanisms of human diseases prior to the need for the use of sentient animals.
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38
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Helms AS, Tang VT, O'Leary TS, Friedline S, Wauchope M, Arora A, Wasserman AH, Smith ED, Lee LM, Wen XW, Shavit JA, Liu AP, Previs MJ, Day SM. Effects of MYBPC3 loss-of-function mutations preceding hypertrophic cardiomyopathy. JCI Insight 2020; 5:133782. [PMID: 31877118 DOI: 10.1172/jci.insight.133782] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Accepted: 12/10/2019] [Indexed: 12/21/2022] Open
Abstract
Mutations in cardiac myosin binding protein C (MyBP-C, encoded by MYBPC3) are the most common cause of hypertrophic cardiomyopathy (HCM). Most MYBPC3 mutations result in premature termination codons (PTCs) that cause RNA degradation and a reduction of MyBP-C in HCM patient hearts. However, a reduction in MyBP-C has not been consistently observed in MYBPC3-mutant induced pluripotent stem cell cardiomyocytes (iPSCMs). To determine early MYBPC3 mutation effects, we used patient and genome-engineered iPSCMs. iPSCMs with frameshift mutations were compared with iPSCMs with MYBPC3 promoter and translational start site deletions, revealing that allelic loss of function is the primary inciting consequence of mutations causing PTCs. Despite a reduction in wild-type mRNA in all heterozygous iPSCMs, no reduction in MyBP-C protein was observed, indicating protein-level compensation through what we believe is a previously uncharacterized mechanism. Although homozygous mutant iPSCMs exhibited contractile dysregulation, heterozygous mutant iPSCMs had normal contractile function in the context of compensated MyBP-C levels. Agnostic RNA-Seq analysis revealed differential expression in genes involved in protein folding as the only dysregulated gene set. To determine how MYBPC3-mutant iPSCMs achieve compensated MyBP-C levels, sarcomeric protein synthesis and degradation were measured with stable isotope labeling. Heterozygous mutant iPSCMs showed reduced MyBP-C synthesis rates but a slower rate of MyBP-C degradation. These findings indicate that cardiomyocytes have an innate capacity to attain normal MyBP-C stoichiometry despite MYBPC3 allelic loss of function due to truncating mutations. Modulating MyBP-C degradation to maintain MyBP-C protein levels may be a novel treatment approach upstream of contractile dysfunction for HCM.
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Affiliation(s)
- Adam S Helms
- Department of Internal Medicine, Division of Cardiovascular Medicine, University of Michigan, Ann Arbor, Michigan, USA
| | - Vi T Tang
- Department of Internal Medicine, Division of Cardiovascular Medicine, University of Michigan, Ann Arbor, Michigan, USA
| | - Thomas S O'Leary
- Department of Molecular Physiology & Biophysics, University of Vermont, Burlington, Vermont, USA
| | - Sabrina Friedline
- Department of Internal Medicine, Division of Cardiovascular Medicine, University of Michigan, Ann Arbor, Michigan, USA
| | - Mick Wauchope
- Department of Internal Medicine, Division of Cardiovascular Medicine, University of Michigan, Ann Arbor, Michigan, USA
| | - Akul Arora
- Department of Internal Medicine, Division of Cardiovascular Medicine, University of Michigan, Ann Arbor, Michigan, USA
| | | | - Eric D Smith
- Department of Internal Medicine, Division of Cardiovascular Medicine, University of Michigan, Ann Arbor, Michigan, USA
| | | | | | | | - Allen P Liu
- Mechanical Engineering.,Biophysics, University of Michigan, Ann Arbor, Michigan, USA
| | - Michael J Previs
- Department of Molecular Physiology & Biophysics, University of Vermont, Burlington, Vermont, USA
| | - Sharlene M Day
- Department of Internal Medicine, Division of Cardiovascular Medicine, University of Michigan, Ann Arbor, Michigan, USA.,Departments of Molecular and Integrative Physiology
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39
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Skeletal MyBP-C isoforms tune the molecular contractility of divergent skeletal muscle systems. Proc Natl Acad Sci U S A 2019; 116:21882-21892. [PMID: 31591218 DOI: 10.1073/pnas.1910549116] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Skeletal muscle myosin-binding protein C (MyBP-C) is a myosin thick filament-associated protein, localized through its C terminus to distinct regions (C-zones) of the sarcomere. MyBP-C modulates muscle contractility, presumably through its N terminus extending from the thick filament and interacting with either the myosin head region and/or the actin thin filament. Two isoforms of MyBP-C (fast- and slow-type) are expressed in a muscle type-specific manner. Are the expression, localization, and Ca2+-dependent modulatory capacities of these isoforms different in fast-twitch extensor digitorum longus (EDL) and slow-twitch soleus (SOL) muscles derived from Sprague-Dawley rats? By mass spectrometry, 4 MyBP-C isoforms (1 fast-type MyBP-C and 3 N-terminally spliced slow-type MyBP-C) were expressed in EDL, but only the 3 slow-type MyBP-C isoforms in SOL. Using EDL and SOL native thick filaments in which the MyBP-C stoichiometry and localization are preserved, native thin filament sliding over these thick filaments showed that, only in the C-zone, MyBP-C Ca2+ sensitizes the thin filament and slows thin filament velocity. These modulatory properties depended on MyBP-C's N terminus as N-terminal proteolysis attenuated MyBP-C's functional capacities. To determine each MyBP-C isoform's contribution to thin filament Ca2+ sensitization and slowing in the C-zone, we used a combination of in vitro motility assays using expressed recombinant N-terminal fragments and in silico mechanistic modeling. Our results suggest that each skeletal MyBP-C isoform's N terminus is functionally distinct and has modulatory capacities that depend on the muscle type in which they are expressed, providing the potential for molecular tuning of skeletal muscle performance through differential MyBP-C expression.
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Burghardt TP. Demographic model for inheritable cardiac disease. Arch Biochem Biophys 2019; 672:108056. [PMID: 31356777 DOI: 10.1016/j.abb.2019.07.021] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Revised: 07/24/2019] [Accepted: 07/25/2019] [Indexed: 11/15/2022]
Abstract
The cardiac muscle proteins, generating and regulating energy transduction during a heartbeat, assemble in the sarcomere into a cyclical machine repetitively translating actin relative to myosin filaments. Myosin is the motor transducing ATP free energy into actin movement against resisting force. Cardiac myosin binding protein C (mybpc3) regulates shortening velocity probably by transient N-terminus binding to actin while its C-terminus strongly binds the myosin filament. Inheritable heart disease associated mutants frequently modify these proteins involving them in disease mechanisms. Nonsynonymous single nucleotide polymorphisms (SNPs) cause single residue substitutions with independent characteristics (sequence location, residue substitution, human demographic, and allele frequency) hypothesized to decide dependent phenotype and pathogenicity characteristics in a feed-forward neural network model. Trial models train and validate on a dynamic worldwide SNP database for cardiac muscle proteins then predict phenotype and pathogenicity for any single residue substitution in myosin, mybpc3, or actin. A separate Bayesian model formulates conditional probabilities for phenotype or pathogenicity given independent SNP characteristics. Neural/Bayes forecasting tests SNP pathogenicity vs (in)dependent SNP characteristics to assess individualized disease risk and in particular to elucidate gender and human subpopulation bias in disease. Evident subpopulation bias in myosin SNP pathogenicities imply myosin normally engages multiple sarcomere proteins functionally. Consistent with this observation, mybpc3 forms a third actomyosin interaction competing with myosin essential light chain N-terminus suggesting a novel strain-dependent mechanism adapting myosin force-velocity to load dynamics. The working models, and the integral myosin/mybpc3 motor concept, portends the wider considerations involved in understanding heart disease as a systemic maladaptation.
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Affiliation(s)
- Thomas P Burghardt
- Department of Biochemistry and Molecular Biology and Physiology and Biomedical Engineering, 200 First St. SW, Mayo Clinic Rochester, Rochester, MN, 55905, USA.
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