1
|
Lee S, Vander Roest AS, Blair CA, Kao K, Bremner SB, Childers MC, Pathak D, Heinrich P, Lee D, Chirikian O, Mohran SE, Roberts B, Smith JE, Jahng JW, Paik DT, Wu JC, Gunawardane RN, Ruppel KM, Mack DL, Pruitt BL, Regnier M, Wu SM, Spudich JA, Bernstein D. Incomplete-penetrant hypertrophic cardiomyopathy MYH7 G256E mutation causes hypercontractility and elevated mitochondrial respiration. Proc Natl Acad Sci U S A 2024; 121:e2318413121. [PMID: 38683993 PMCID: PMC11087781 DOI: 10.1073/pnas.2318413121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2023] [Accepted: 03/05/2024] [Indexed: 05/02/2024] Open
Abstract
Determining the pathogenicity of hypertrophic cardiomyopathy-associated mutations in the β-myosin heavy chain (MYH7) can be challenging due to its variable penetrance and clinical severity. This study investigates the early pathogenic effects of the incomplete-penetrant MYH7 G256E mutation on myosin function that may trigger pathogenic adaptations and hypertrophy. We hypothesized that the G256E mutation would alter myosin biomechanical function, leading to changes in cellular functions. We developed a collaborative pipeline to characterize myosin function across protein, myofibril, cell, and tissue levels to determine the multiscale effects on structure-function of the contractile apparatus and its implications for gene regulation and metabolic state. The G256E mutation disrupts the transducer region of the S1 head and reduces the fraction of myosin in the folded-back state by 33%, resulting in more myosin heads available for contraction. Myofibrils from gene-edited MYH7WT/G256E human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) exhibited greater and faster tension development. This hypercontractile phenotype persisted in single-cell hiPSC-CMs and engineered heart tissues. We demonstrated consistent hypercontractile myosin function as a primary consequence of the MYH7 G256E mutation across scales, highlighting the pathogenicity of this gene variant. Single-cell transcriptomic and metabolic profiling demonstrated upregulated mitochondrial genes and increased mitochondrial respiration, indicating early bioenergetic alterations. This work highlights the benefit of our multiscale platform to systematically evaluate the pathogenicity of gene variants at the protein and contractile organelle level and their early consequences on cellular and tissue function. We believe this platform can help elucidate the genotype-phenotype relationships underlying other genetic cardiovascular diseases.
Collapse
Affiliation(s)
- Soah Lee
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA94305
- Department of Biopharmaceutical Convergence, Sungkyunkwan University School of Pharmacy, Suwon, Gyeonggi-do16419South Korea
- School of Pharmacy, Sungkyunkwan University School of Pharmacy, Suwon, Gyeonggi-do16419, South Korea
| | - Alison S. Vander Roest
- Department of Pediatrics (Cardiology), Stanford University School of Medicine, Stanford, CA94305
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI48109
| | - Cheavar A. Blair
- Biological Engineering, University of California, Santa Barbara, CA93106
- Department of Physiology, College of Medicine, University of Kentucky, Lexington, KY40536
| | - Kerry Kao
- Department of Bioengineering, University of Washington School of Medicine and College of Engineering, Seattle, WA98195
| | - Samantha B. Bremner
- Department of Bioengineering, University of Washington School of Medicine and College of Engineering, Seattle, WA98195
| | - Matthew C. Childers
- Department of Bioengineering, University of Washington School of Medicine and College of Engineering, Seattle, WA98195
| | - Divya Pathak
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA94305
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA94305
| | - Paul Heinrich
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA94305
| | - Daniel Lee
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA94305
| | - Orlando Chirikian
- Biological Engineering, University of California, Santa Barbara, CA93106
| | - Saffie E. Mohran
- Department of Bioengineering, University of Washington School of Medicine and College of Engineering, Seattle, WA98195
| | | | | | - James W. Jahng
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA94305
| | - David T. Paik
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA94305
| | - Joseph C. Wu
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA94305
- Division of Cardiovascular Medicine, Department of Medicine, Stanford University School of Medicine, Stanford, CA94305
| | | | - Kathleen M. Ruppel
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA94305
| | - David L. Mack
- Department of Bioengineering, University of Washington School of Medicine and College of Engineering, Seattle, WA98195
| | - Beth L. Pruitt
- Biological Engineering, University of California, Santa Barbara, CA93106
| | - Michael Regnier
- Department of Bioengineering, University of Washington School of Medicine and College of Engineering, Seattle, WA98195
| | - Sean M. Wu
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA94305
- Division of Cardiovascular Medicine, Department of Medicine, Stanford University School of Medicine, Stanford, CA94305
| | - James A. Spudich
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA94305
| | - Daniel Bernstein
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA94305
- Department of Pediatrics (Cardiology), Stanford University School of Medicine, Stanford, CA94305
| |
Collapse
|
2
|
Lee S, Roest ASV, Blair CA, Kao K, Bremner SB, Childers MC, Pathak D, Heinrich P, Lee D, Chirikian O, Mohran S, Roberts B, Smith JE, Jahng JW, Paik DT, Wu JC, Gunawardane RN, Spudich JA, Ruppel K, Mack D, Pruitt BL, Regnier M, Wu SM, Bernstein D. Multi-scale models reveal hypertrophic cardiomyopathy MYH7 G256E mutation drives hypercontractility and elevated mitochondrial respiration. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.08.544276. [PMID: 37333118 PMCID: PMC10274883 DOI: 10.1101/2023.06.08.544276] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/20/2023]
Abstract
Rationale Over 200 mutations in the sarcomeric protein β-myosin heavy chain (MYH7) have been linked to hypertrophic cardiomyopathy (HCM). However, different mutations in MYH7 lead to variable penetrance and clinical severity, and alter myosin function to varying degrees, making it difficult to determine genotype-phenotype relationships, especially when caused by rare gene variants such as the G256E mutation. Objective This study aims to determine the effects of low penetrant MYH7 G256E mutation on myosin function. We hypothesize that the G256E mutation would alter myosin function, precipitating compensatory responses in cellular functions. Methods We developed a collaborative pipeline to characterize myosin function at multiple scales (protein to myofibril to cell to tissue). We also used our previously published data on other mutations to compare the degree to which myosin function was altered. Results At the protein level, the G256E mutation disrupts the transducer region of the S1 head and reduces the fraction of myosin in the folded-back state by 50.9%, suggesting more myosins available for contraction. Myofibrils isolated from hiPSC-CMs CRISPR-edited with G256E (MYH7 WT/G256E ) generated greater tension, had faster tension development and slower early phase relaxation, suggesting altered myosin-actin crossbridge cycling kinetics. This hypercontractile phenotype persisted in single-cell hiPSC-CMs and engineered heart tissues. Single-cell transcriptomic and metabolic profiling demonstrated upregulation of mitochondrial genes and increased mitochondrial respiration, suggesting altered bioenergetics as an early feature of HCM. Conclusions MYH7 G256E mutation causes structural instability in the transducer region, leading to hypercontractility across scales, perhaps from increased myosin recruitment and altered crossbridge cycling. Hypercontractile function of the mutant myosin was accompanied by increased mitochondrial respiration, while cellular hypertrophy was modest in the physiological stiffness environment. We believe that this multi-scale platform will be useful to elucidate genotype-phenotype relationships underlying other genetic cardiovascular diseases.
Collapse
|
3
|
Kucher AN, Valiakhmetov NR, Salakhov RR, Golubenko MV, Pavlyukova EN, Nazarenko MS. Phenotype variation of hypertrophic cardiomyopathy in carriers of the p.Arg870His pathogenic variant in the MYH7 gene. BULLETIN OF SIBERIAN MEDICINE 2022. [DOI: 10.20538/1682-0363-2022-3-205-216] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The review analyzes variability of clinical manifestations of p.Arg870His in the MYH7 gene, which is repeatedly registered in patients with hypertrophic cardiomyopathy (HCM). The analysis involves the data from scientific publications obtained as a search result in the PubMed, СlinVar, and eLibrary.ru databases, as well as authors’ own results. A wide range of phenotypic manifestations have been revealed in carriers of p.Arg870His, from the asymptomatic to severe course, rapid progression, and early death. The review considers possible factors that modify the effect of the pathogenic variant (i.e. dosage of the pathogenic variant, the presence of other unfavorable genetic variants, etc.). The importance of accumulating information on the clinical features of HCM in the carriers of specific gene variants is emphasized in order to clarify their pathogenicity and to identify factors modifying the clinical outcome, which is important for the choice of the treatment strategy for HCM.
Collapse
Affiliation(s)
- A. N. Kucher
- Research Institute of Medical Genetics, Tomsk National Research Medical Center (NRMC), Russian Academy of Sciences
| | - N. R. Valiakhmetov
- Research Institute of Medical Genetics, Tomsk National Research Medical Center (NRMC), Russian Academy of Sciences
| | - R. R. Salakhov
- Research Institute of Medical Genetics, Tomsk National Research Medical Center (NRMC), Russian Academy of Sciences; Siberian State Medical University
| | - M. V. Golubenko
- Research Institute of Medical Genetics, Tomsk National Research Medical Center (NRMC), Russian Academy of Sciences
| | - E. N. Pavlyukova
- Cardiology Research Institute, Tomsk National Research Medical Center (NRMC), Russian Academy of Sciences
| | - M. S. Nazarenko
- Research Institute of Medical Genetics, Tomsk National Research Medical Center (NRMC), Russian Academy of Sciences; Siberian State Medical University
| |
Collapse
|
4
|
Kawana M, Spudich JA, Ruppel KM. Hypertrophic cardiomyopathy: Mutations to mechanisms to therapies. Front Physiol 2022; 13:975076. [PMID: 36225299 PMCID: PMC9548533 DOI: 10.3389/fphys.2022.975076] [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] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Accepted: 08/22/2022] [Indexed: 01/10/2023] Open
Abstract
Hypertrophic cardiomyopathy (HCM) affects more than 1 in 500 people in the general population with an extensive burden of morbidity in the form of arrhythmia, heart failure, and sudden death. More than 25 years since the discovery of the genetic underpinnings of HCM, the field has unveiled significant insights into the primary effects of these genetic mutations, especially for the myosin heavy chain gene, which is one of the most commonly mutated genes. Our group has studied the molecular effects of HCM mutations on human β-cardiac myosin heavy chain using state-of-the-art biochemical and biophysical tools for the past 10 years, combining insights from clinical genetics and structural analyses of cardiac myosin. The overarching hypothesis is that HCM-causing mutations in sarcomere proteins cause hypercontractility at the sarcomere level, and we have shown that an increase in the number of myosin molecules available for interaction with actin is a primary driver. Recently, two pharmaceutical companies have developed small molecule inhibitors of human cardiac myosin to counteract the molecular consequences of HCM pathogenesis. One of these inhibitors (mavacamten) has recently been approved by the FDA after completing a successful phase III trial in HCM patients, and the other (aficamten) is currently being evaluated in a phase III trial. Myosin inhibitors will be the first class of medication used to treat HCM that has both robust clinical trial evidence of efficacy and that targets the fundamental mechanism of HCM pathogenesis. The success of myosin inhibitors in HCM opens the door to finding other new drugs that target the sarcomere directly, as we learn more about the genetics and fundamental mechanisms of this disease.
Collapse
Affiliation(s)
- Masataka Kawana
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA, United States,Department of Medicine, Division of Cardiovascular Medicine, Stanford University School of Medicine, Stanford, CA, United States
| | - James A. Spudich
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA, United States
| | - Kathleen M. Ruppel
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA, United States,*Correspondence: Kathleen M. Ruppel,
| |
Collapse
|
5
|
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.
Collapse
|
6
|
Collyer J, Xu F, Munkhsaikhan U, Alberson NF, Orgil BO, Zhang W, Czosek RJ, Lu L, Jefferies JL, Towbin JA, Purevjav E. Combining whole exome sequencing with in silico analysis and clinical data to identify candidate variants in pediatric left ventricular noncompaction. Int J Cardiol 2022; 347:29-37. [PMID: 34752814 DOI: 10.1016/j.ijcard.2021.11.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 10/27/2021] [Accepted: 11/03/2021] [Indexed: 11/24/2022]
Abstract
BACKGROUND Understanding the overall variant burden in pediatric patients with left ventricular noncompaction (LVNC) has clinical implications. Whole exome sequencing (WES) allows detection of coding variants in both candidate cardiomyopathy genes and those included on commercial panels. Other lines of evidence, including in silico analysis, are necessary to reduce the overwhelming number of variants to those most likely having a phenotypic impact. METHODS Five families, including five pediatric probands with LVNC, 5 other affected, and 10 unaffected family members, had WES performed, followed by bioinformatics filtering and Sanger sequencing. Review of the HGMD, variant classification by ACMG guidelines, and clinical information were used to further refine complex genotypes. RESULTS One nonsense and eleven missense variants were identified. In Family 1, affected siblings carried digenic heterozygous variants: E1350K-MYH7 and A276V-ANKRD1. The proband also carried heterozygous W143X-NRG1. Four affected members of Family 2 carried K184Q-MYH7 while unaffected members did not. In Family 3, homozygous A161T-MYH7 and heterozygous P4935T-OBSCN variants were identified in the proband with the latter being absent in his unaffected brother. In Family 4, proband's father and half-sibling have mild hypertrabeculation and carry T3796I-PLEC. The proband, carrying T3796I-PLEC and V2878A-OBSCN, demonstrated higher trabeculation burden. The proband in Family 5 carried four variants, R3247W-PLEC, C92Y-ERG, T1233M-NCOR2, and E54K-HIST1H4B. Application of ACMG criteria and clinical data revealed that W143X-NRG1, P4935T-OBSCN, and V2878A-OBSCN likely have no phenotypic role. CONCLUSIONS We report nine variants, including novel T3796I-PLEC and biallelic A161T-MYH7, likely contributing to phenotypes ranging from asymptomatic hypertrabeculation to severe LVNC with heart failure.
Collapse
Affiliation(s)
- John Collyer
- Department of Pediatrics, University of Tennessee Health Science Center, Memphis, TN, United States of America; Children's Foundation Research Institute, Le Bonheur Children's Hospital, Memphis, TN, United States of America
| | - Fuyi Xu
- Department of Genetics, Genomics and Informatics, University of Tennessee Health Science Center, Memphis, TN, United States of America; School of Pharmacy, Binzhou Medical University, Yantai, Shandong 264003, China
| | - Undral Munkhsaikhan
- Department of Pediatrics, University of Tennessee Health Science Center, Memphis, TN, United States of America; Children's Foundation Research Institute, Le Bonheur Children's Hospital, Memphis, TN, United States of America
| | - Neely F Alberson
- Department of Pediatrics, University of Tennessee Health Science Center, Memphis, TN, United States of America; Children's Foundation Research Institute, Le Bonheur Children's Hospital, Memphis, TN, United States of America
| | - Buyan-Ochir Orgil
- Department of Pediatrics, University of Tennessee Health Science Center, Memphis, TN, United States of America; Children's Foundation Research Institute, Le Bonheur Children's Hospital, Memphis, TN, United States of America
| | - Wenying Zhang
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, United States of America; Laboratory of Genetics and Genomics, Division of Human Genetics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States of America
| | - Richard J Czosek
- Heart Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States of America
| | - Lu Lu
- Department of Genetics, Genomics and Informatics, University of Tennessee Health Science Center, Memphis, TN, United States of America
| | - John L Jefferies
- Division of Adult Cardiovascular Diseases, University of Tennessee Health Science Center, Memphis, TN, United States of America; Pediatric Cardiology, Le Bonheur Children's Hospital, Memphis, TN, United States of America; Pediatric Cardiology, St. Jude Children's Research Hospital, Memphis, TN, United States of America
| | - Jeffrey A Towbin
- Department of Pediatrics, University of Tennessee Health Science Center, Memphis, TN, United States of America; Pediatric Cardiology, Le Bonheur Children's Hospital, Memphis, TN, United States of America; Pediatric Cardiology, St. Jude Children's Research Hospital, Memphis, TN, United States of America
| | - Enkhsaikhan Purevjav
- Department of Pediatrics, University of Tennessee Health Science Center, Memphis, TN, United States of America; Children's Foundation Research Institute, Le Bonheur Children's Hospital, Memphis, TN, United States of America.
| |
Collapse
|
7
|
Bu H, Ding Y, Li J, Zhu P, Shih YH, Wang M, Zhang Y, Lin X, Xu X. Inhibition of mTOR or MAPK ameliorates vmhcl/myh7 cardiomyopathy in zebrafish. JCI Insight 2021; 6:154215. [PMID: 34935644 PMCID: PMC8783688 DOI: 10.1172/jci.insight.154215] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Accepted: 11/03/2021] [Indexed: 01/25/2023] Open
Abstract
Myosin heavy chain 7 (MYH7) is a major causative gene for hypertrophic cardiomyopathy, but the affected signaling pathways and therapeutics remain elusive. In this research, we identified ventricle myosin heavy chain like (vmhcl) as a zebrafish homolog of human MYH7, and we generated vmhcl frameshift mutants. We noted vmhcl-based embryonic cardiac dysfunction (VEC) in the vmhcl homozygous mutants and vmhcl-based adult cardiomyopathy (VAC) phenotypes in the vmhcl heterozygous mutants. Using the VEC model, we assessed 7 known cardiomyopathy signaling pathways pharmacologically and 11 candidate genes genetically via CRISPR/Cas9 genome editing technology based on microhomology-mediated end joining (MMEJ). Both studies converged on therapeutic benefits of mTOR or mitogen-activated protein kinase (MAPK) inhibition of VEC. While mTOR inhibition rescued the enlarged nuclear size of cardiomyocytes, MAPK inhibition restored the prolonged cell shape in the VEC model. The therapeutic effects of mTOR and MAPK inhibition were later validated in the VAC model. Together, vmhcl/myh7 loss of function is sufficient to induce cardiomyopathy in zebrafish. The VEC and VAC models in zebrafish are amenable to both efficient genetic and chemical genetic tools, offering a rapid in vivo platform for discovering candidate signaling pathways of MYH7 cardiomyopathy.
Collapse
Affiliation(s)
- Haisong Bu
- Department of Biochemistry and Molecular Biology, Department of Cardiovascular Medicine, Mayo Clinic, Rochester, Minnesota, USA.,Department of Cardiothoracic Surgery, Xiangya Hospital, Central South University, Changsha, China
| | - Yonghe Ding
- Department of Biochemistry and Molecular Biology, Department of Cardiovascular Medicine, Mayo Clinic, Rochester, Minnesota, USA
| | - Jiarong Li
- Department of Biochemistry and Molecular Biology, Department of Cardiovascular Medicine, Mayo Clinic, Rochester, Minnesota, USA.,Department of Cardiovascular Surgery, The Second Xiangya Hospital of Central South University, Changsha, China
| | - Ping Zhu
- Department of Biochemistry and Molecular Biology, Department of Cardiovascular Medicine, Mayo Clinic, Rochester, Minnesota, USA
| | - Yu-Huan Shih
- Department of Biochemistry and Molecular Biology, Department of Cardiovascular Medicine, Mayo Clinic, Rochester, Minnesota, USA
| | - Mingmin Wang
- Department of Biochemistry and Molecular Biology, Department of Cardiovascular Medicine, Mayo Clinic, Rochester, Minnesota, USA.,Dongzhimen Hospital, Beijing University of Chinese Medicine, Beijing, China
| | - Yuji Zhang
- Department of Epidemiology and Public Health, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Xueying Lin
- Department of Biochemistry and Molecular Biology, Department of Cardiovascular Medicine, Mayo Clinic, Rochester, Minnesota, USA
| | - Xiaolei Xu
- Department of Biochemistry and Molecular Biology, Department of Cardiovascular Medicine, Mayo Clinic, Rochester, Minnesota, USA
| |
Collapse
|
8
|
Barrick SK, Greenberg MJ. Cardiac myosin contraction and mechanotransduction in health and disease. J Biol Chem 2021; 297:101297. [PMID: 34634306 PMCID: PMC8559575 DOI: 10.1016/j.jbc.2021.101297] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 10/06/2021] [Accepted: 10/07/2021] [Indexed: 12/17/2022] Open
Abstract
Cardiac myosin is the molecular motor that powers heart contraction by converting chemical energy from ATP hydrolysis into mechanical force. The power output of the heart is tightly regulated to meet the physiological needs of the body. Recent multiscale studies spanning from molecules to tissues have revealed complex regulatory mechanisms that fine-tune cardiac contraction, in which myosin not only generates power output but also plays an active role in its regulation. Thus, myosin is both shaped by and actively involved in shaping its mechanical environment. Moreover, these studies have shown that cardiac myosin-generated tension affects physiological processes beyond muscle contraction. Here, we review these novel regulatory mechanisms, as well as the roles that myosin-based force generation and mechanotransduction play in development and disease. We describe how key intra- and intermolecular interactions contribute to the regulation of myosin-based contractility and the role of mechanical forces in tuning myosin function. We also discuss the emergence of cardiac myosin as a drug target for diseases including heart failure, leading to the discovery of therapeutics that directly tune myosin contractility. Finally, we highlight some of the outstanding questions that must be addressed to better understand myosin's functions and regulation, and we discuss prospects for translating these discoveries into precision medicine therapeutics targeting contractility and mechanotransduction.
Collapse
Affiliation(s)
- Samantha K Barrick
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Michael J Greenberg
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri, USA.
| |
Collapse
|
9
|
Greenberg MJ, Tardiff JC. Complexity in genetic cardiomyopathies and new approaches for mechanism-based precision medicine. J Gen Physiol 2021; 153:211741. [PMID: 33512404 PMCID: PMC7852459 DOI: 10.1085/jgp.202012662] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2020] [Accepted: 01/07/2021] [Indexed: 12/11/2022] Open
Abstract
Genetic cardiomyopathies have been studied for decades, and it has become increasingly clear that these progressive diseases are more complex than originally thought. These complexities can be seen both in the molecular etiologies of these disorders and in the clinical phenotypes observed in patients. While these disorders can be caused by mutations in cardiac genes, including ones encoding sarcomeric proteins, the disease presentation varies depending on the patient mutation, where mutations even within the same gene can cause divergent phenotypes. Moreover, it is challenging to connect the mutation-induced molecular insult that drives the disease pathogenesis with the various compensatory and maladaptive pathways that are activated during the course of the subsequent progressive, pathogenic cardiac remodeling. These inherent complexities have frustrated our ability to understand and develop broadly effective treatments for these disorders. It has been proposed that it might be possible to improve patient outcomes by adopting a precision medicine approach. Here, we lay out a practical framework for such an approach, where patient subpopulations are binned based on common underlying biophysical mechanisms that drive the molecular disease pathogenesis, and we propose that this function-based approach will enable the development of targeted therapeutics that ameliorate these effects. We highlight several mutations to illustrate the need for mechanistic molecular experiments that span organizational and temporal scales, and we describe recent advances in the development of novel therapeutics based on functional targets. Finally, we describe many of the outstanding questions for the field and how fundamental mechanistic studies, informed by our more nuanced understanding of the clinical disorders, will play a central role in realizing the potential of precision medicine for genetic cardiomyopathies.
Collapse
Affiliation(s)
- Michael J Greenberg
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO
| | - Jil C Tardiff
- Department of Biomedical Engineering, University of Arizona, Tucson, AZ.,Department of Medicine, University of Arizona, Tucson, AZ
| |
Collapse
|
10
|
Alpha and beta myosin isoforms and human atrial and ventricular contraction. Cell Mol Life Sci 2021; 78:7309-7337. [PMID: 34704115 PMCID: PMC8629898 DOI: 10.1007/s00018-021-03971-y] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Revised: 10/03/2021] [Accepted: 10/08/2021] [Indexed: 01/15/2023]
Abstract
Human atrial and ventricular contractions have distinct mechanical characteristics including speed of contraction, volume of blood delivered and the range of pressure generated. Notably, the ventricle expresses predominantly β-cardiac myosin while the atrium expresses mostly the α-isoform. In recent years exploration of the properties of pure α- & β-myosin isoforms have been possible in solution, in isolated myocytes and myofibrils. This allows us to consider the extent to which the atrial vs ventricular mechanical characteristics are defined by the myosin isoform expressed, and how the isoform properties are matched to their physiological roles. To do this we Outline the essential feature of atrial and ventricular contraction; Explore the molecular structural and functional characteristics of the two myosin isoforms; Describe the contractile behaviour of myocytes and myofibrils expressing a single myosin isoform; Finally we outline the outstanding problems in defining the differences between the atria and ventricles. This allowed us consider what features of contraction can and cannot be ascribed to the myosin isoforms present in the atria and ventricles.
Collapse
|
11
|
Alessi CE, Wu Q, Whitaker CH, Felice KJ. Laing Myopathy: Report of 4 New Families With Novel MYH7 Mutations, Double Mutations, and Severe Phenotype. J Clin Neuromuscul Dis 2020; 22:22-34. [PMID: 32833721 DOI: 10.1097/cnd.0000000000000297] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Laing distal myopathy (LDM) is an autosomal dominant disorder caused by mutations in the slow skeletal muscle fiber myosin heavy chain (MYH7) gene on chromosome 14q11.2. The classic LDM phenotype-including early-onset, initial involvement of foot dorsiflexors and great toe extensors, followed by weakness of neck flexors and finger extensors-is well documented. Since the original report by Laing et al in 1995, the spectrum of MYH7-related myopathies has expanded to include congenital myopathies, late-onset myopathies, myosin storage myopathy, and scapuloperoneal myopathies. Most patients with LDM harbor mutations in the midrod domain of the MYH7 gene, but rare cases document disease-associated mutations in the globular head region. In this report, we add to the medical literature by describing the clinicopathological findings in 8 affected family members from 4 new LDM families-including 2 with novel MYH7 mutations (Y162D and A1438P), one with dual mutations (V39M and K1617del), and one family (E1508del) with severe early-onset weakness associated with contractures, respiratory insufficiency, and dilated cardiomyopathy. Our families highlight the ever-expanding clinical spectrum and genetic variation of the skeletal myopathies related to MYH7 gene mutations.
Collapse
Affiliation(s)
| | - Qian Wu
- Pathology and Laboratory Medicine, University of Connecticut School of Medicine, Farmington, CT; and
| | - Charles H Whitaker
- Department of Neuromuscular Medicine, Muscular Dystrophy Association Care Center, Hospital for Special Care, New Britain, CT
| | - Kevin J Felice
- Department of Neuromuscular Medicine, Muscular Dystrophy Association Care Center, Hospital for Special Care, New Britain, CT
| |
Collapse
|
12
|
Tsukamoto O. Direct Sarcomere Modulators Are Promising New Treatments for Cardiomyopathies. Int J Mol Sci 2019; 21:ijms21010226. [PMID: 31905684 PMCID: PMC6982115 DOI: 10.3390/ijms21010226] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Revised: 12/24/2019] [Accepted: 12/25/2019] [Indexed: 01/10/2023] Open
Abstract
Mutations in sarcomere genes can cause both hypertrophic cardiomyopathy (HCM) and dilated cardiomyopathy (DCM). However, the complex genotype-phenotype relationships in pathophysiology of cardiomyopathies by gene or mutation location are not fully understood. In addition, it is still unclear how mutations within same molecule result in different clinical phenotypes such as HCM and DCM. To clarify how the initial functional insult caused by a subtle change in one protein component of the sarcomere with a given mutation is critical for the development of proper effective treatments for cardiomyopathies. Fortunately, recent technological advances and the development of direct sarcomere modulators have provided a more detailed understanding of the molecular mechanisms that govern the effects of specific mutations. The direct inhibition of sarcomere contractility may be able to suppress the development and progression of HCM with hypercontractile mutations and improve clinical parameters in patients with HCM. On the other hand, direct activation of sarcomere contractility appears to exert unexpected beneficial effects such as reverse remodeling and lower heart rate without increasing adverse cardiovascular events in patients with systolic heart failure due to DCM. Direct sarcomere modulators that can positively influence the natural history of cardiomyopathies represent promising treatment options.
Collapse
Affiliation(s)
- Osamu Tsukamoto
- Department of Medical Biochemistry, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita 565-0871, Japan; ; Tel.: +81-6-6879-3492
- Department of Medical Biochemistry, Graduate School of Frontier Bioscience, Osaka University, 1-1 Yamadaoka, Suita 565-0871, Japan
| |
Collapse
|
13
|
Kanavy DM, McNulty SM, Jairath MK, Brnich SE, Bizon C, Powell BC, Berg JS. Comparative analysis of functional assay evidence use by ClinGen Variant Curation Expert Panels. Genome Med 2019; 11:77. [PMID: 31783775 PMCID: PMC6884856 DOI: 10.1186/s13073-019-0683-1] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Accepted: 11/05/2019] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND The 2015 American College of Medical Genetics and Genomics (ACMG) and the Association for Molecular Pathology (AMP) guidelines for clinical sequence variant interpretation state that "well-established" functional studies can be used as evidence in variant classification. These guidelines articulated key attributes of functional data, including that assays should reflect the biological environment and be analytically sound; however, details of how to evaluate these attributes were left to expert judgment. The Clinical Genome Resource (ClinGen) designates Variant Curation Expert Panels (VCEPs) in specific disease areas to make gene-centric specifications to the ACMG/AMP guidelines, including more specific definitions of appropriate functional assays. We set out to evaluate the existing VCEP guidelines for functional assays. METHODS We evaluated the functional criteria (PS3/BS3) of six VCEPs (CDH1, Hearing Loss, Inherited Cardiomyopathy-MYH7, PAH, PTEN, RASopathy). We then established criteria for evaluating functional studies based on disease mechanism, general class of assay, and the characteristics of specific assay instances described in the primary literature. Using these criteria, we extensively curated assay instances cited by each VCEP in their pilot variant classification to analyze VCEP recommendations and their use in the interpretation of functional studies. RESULTS Unsurprisingly, our analysis highlighted the breadth of VCEP-approved assays, reflecting the diversity of disease mechanisms among VCEPs. We also noted substantial variability between VCEPs in the method used to select these assays and in the approach used to specify strength modifications, as well as differences in suggested validation parameters. Importantly, we observed discrepancies between the parameters VCEPs specified as required for approved assay instances and the fulfillment of these requirements in the individual assays cited in pilot variant interpretation. CONCLUSIONS Interpretation of the intricacies of functional assays often requires expert-level knowledge of the gene and disease, and current VCEP recommendations for functional assay evidence are a useful tool to improve the accessibility of functional data by providing a starting point for curators to identify approved functional assays and key metrics. However, our analysis suggests that further guidance is needed to standardize this process and ensure consistency in the application of functional evidence.
Collapse
Affiliation(s)
- Dona M Kanavy
- Department of Genetics, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Shannon M McNulty
- Department of Genetics, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Meera K Jairath
- Department of Genetics, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Sarah E Brnich
- Department of Genetics, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Chris Bizon
- Renaissance Computing Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Bradford C Powell
- Department of Genetics, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Jonathan S Berg
- Department of Genetics, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
| |
Collapse
|
14
|
Mosqueira D, Smith JGW, Bhagwan JR, Denning C. Modeling Hypertrophic Cardiomyopathy: Mechanistic Insights and Pharmacological Intervention. Trends Mol Med 2019; 25:775-790. [PMID: 31324451 DOI: 10.1016/j.molmed.2019.06.005] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Revised: 06/12/2019] [Accepted: 06/18/2019] [Indexed: 02/06/2023]
Abstract
Hypertrophic cardiomyopathy (HCM) is a prevalent and complex cardiovascular disease where cardiac dysfunction often associates with mutations in sarcomeric genes. Various models based on tissue explants, isolated cardiomyocytes, skinned myofibrils, and purified actin/myosin preparations have uncovered disease hallmarks, enabling the development of putative therapeutics, with some reaching clinical trials. Newly developed human pluripotent stem cell (hPSC)-based models could be complementary by overcoming some of the inconsistencies of earlier systems, whilst challenging and/or clarifying previous findings. In this article we compare recent progress in unveiling multiple HCM mechanisms in different models, highlighting similarities and discrepancies. We explore how insight is facilitating the design of new HCM therapeutics, including those that regulate metabolism, contraction and heart rhythm, providing a future perspective for treatment of HCM.
Collapse
Affiliation(s)
- Diogo Mosqueira
- Department of Stem Cell Biology, Centre of Biomolecular Sciences, University of Nottingham, Nottingham NG7 2RD, UK.
| | - James G W Smith
- Faculty of Medicine and Health Sciences, Norwich Medical School, University of East Anglia, Norwich Research Park, Norwich NR4 7UQ, UK
| | - Jamie R Bhagwan
- Department of Stem Cell Biology, Centre of Biomolecular Sciences, University of Nottingham, Nottingham NG7 2RD, UK
| | - Chris Denning
- Department of Stem Cell Biology, Centre of Biomolecular Sciences, University of Nottingham, Nottingham NG7 2RD, UK
| |
Collapse
|
15
|
Reza N, Chowns JL, Marzolf A, Owens AT. Good Intentions Gone Bad. CIRCULATION-GENOMIC AND PRECISION MEDICINE 2019; 12:e002560. [PMID: 31112422 DOI: 10.1161/circgen.119.002560] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Nosheen Reza
- Center for Inherited Cardiovascular Disease, Division of Cardiovascular Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia
| | - Jessica L Chowns
- Center for Inherited Cardiovascular Disease, Division of Cardiovascular Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia
| | - Amy Marzolf
- Center for Inherited Cardiovascular Disease, Division of Cardiovascular Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia
| | - Anjali Tiku Owens
- Center for Inherited Cardiovascular Disease, Division of Cardiovascular Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia
| |
Collapse
|
16
|
Bell KM, Kronert WA, Huang A, Bernstein SI, Swank DM. The R249Q hypertrophic cardiomyopathy myosin mutation decreases contractility in Drosophila by impeding force production. J Physiol 2019; 597:2403-2420. [PMID: 30950055 DOI: 10.1113/jp277333] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Accepted: 03/06/2019] [Indexed: 12/18/2022] Open
Abstract
KEY POINTS Hypertrophic cardiomyopathy (HCM) is a genetic disease that causes thickening of the heart's ventricular walls and is a leading cause of sudden cardiac death. HCM is caused by missense mutations in muscle proteins including myosin, but how these mutations alter muscle mechanical performance in largely unknown. We investigated the disease mechanism for HCM myosin mutation R249Q by expressing it in the indirect flight muscle of Drosophila melanogaster and measuring alterations to muscle and flight performance. Muscle mechanical analysis revealed R249Q decreased muscle power production due to slower muscle kinetics and decreased force production; force production was reduced because fewer mutant myosin cross-bridges were bound simultaneously to actin. This work does not support the commonly proposed hypothesis that myosin HCM mutations increase muscle contractility, or causes a gain in function; instead, it suggests that for some myosin HCM mutations, hypertrophy is a compensation for decreased contractility. ABSTRACT Hypertrophic cardiomyopathy (HCM) is an inherited disease that causes thickening of the heart's ventricular walls. A generally accepted hypothesis for this phenotype is that myosin heavy chain HCM mutations increase muscle contractility. To test this hypothesis, we expressed an HCM myosin mutation, R249Q, in Drosophila indirect flight muscle (IFM) and assessed myofibril structure, skinned fibre mechanical properties, and flight ability. Mechanics experiments were performed on fibres dissected from 2-h-old adult flies, prior to degradation of IFM myofilament structure, which started at 2 days old and increased with age. Homozygous and heterozygous R249Q fibres showed decreased maximum power generation by 67% and 44%, respectively. Decreases in force and work and slower overall muscle kinetics caused homozygous fibres to produce less power. While heterozygous fibres showed no overall slowing of muscle kinetics, active force and work production dropped by 68% and 47%, respectively, which hindered power production. The muscle apparent rate constant 2πb decreased 33% for homozygous but increased for heterozygous fibres. The apparent rate constant 2πc was greater for homozygous fibres. This indicates that R249Q myosin is slowing attachment while speeding up detachment from actin, resulting in less time bound. Decreased IFM power output caused 43% and 33% decreases in Drosophila flight ability and 19% and 6% drops in wing beat frequency for homozygous and heterozygous flies, respectively. Overall, our results do not support the increased contractility hypothesis. Instead, our results suggest the ventricular hypertrophy for human R249Q mutation is a compensatory response to decreases in heart muscle power output.
Collapse
Affiliation(s)
- Kaylyn M Bell
- Department of Biological Sciences & Biomedical Engineering, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, NY, USA
| | - William A Kronert
- Department of Biology, Molecular Biology Institute and Heart Institute, San Diego State University, San Diego, CA, USA
| | - Alice Huang
- Department of Biological Sciences & Biomedical Engineering, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, NY, USA
| | - Sanford I Bernstein
- Department of Biology, Molecular Biology Institute and Heart Institute, San Diego State University, San Diego, CA, USA
| | - Douglas M Swank
- Department of Biological Sciences & Biomedical Engineering, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, NY, USA
| |
Collapse
|
17
|
Wang Y, Burghardt TP. Uncured PDMS inhibits myosin in vitro motility in a microfluidic flow cell. Anal Biochem 2018; 563:56-60. [PMID: 30300623 PMCID: PMC6689414 DOI: 10.1016/j.ab.2018.10.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Revised: 10/05/2018] [Accepted: 10/05/2018] [Indexed: 10/28/2022]
Abstract
The myosin motor powers cardiac contraction and is frequently implicated in hereditary heart disease by its mutation. Principal motor function characteristics include myosin unitary step size, duty cycle, and force-velocity relationship for translating actin under load. These characteristics are sometimes measured in vitro with a motility assay detecting fluorescent labeled actin filament gliding velocity over a planar array of surface immobilized myosin. Assay miniaturization in a polydimethylsiloxane/glass (PDMS/glass) hybrid microfluidic flow channel is an essential component to a small sample volume assay applicable to costly protein samples however the PDMS substrate dramatically inhibits myosin motility. Myosin in vitro motility in a PDMS/glass hybrid microfluidic flow cell was tested under a variety of conditions to identify and mitigate the effect of PDMS on myosin. Substantial contamination by unpolymerized species in the PDMS flow cells is shown to be the cause of myosin motility inhibition. Normal myosin motility recovers by either extended cell aging (~20 days) to allow more complete polymerization or by direct chemical extraction of the unpolymerized species from the polymer substrate. PDMS flow cell aging is the low cost alternative compatible with the other PDMS and glass modifications needed for in vitro myosin motility assaying.
Collapse
Affiliation(s)
- Yihua Wang
- Department of Biochemistry and Molecular Biology, Mayo Clinic Rochester, Rochester, MN, 55905, USA
| | - Thomas P Burghardt
- Department of Biochemistry and Molecular Biology, Mayo Clinic Rochester, Rochester, MN, 55905, USA; Department of Physiology and Biomedical Engineering, Mayo Clinic Rochester, Rochester, MN, 55905, USA.
| |
Collapse
|
18
|
Hypertrophic cardiomyopathy R403Q mutation in rabbit β-myosin reduces contractile function at the molecular and myofibrillar levels. Proc Natl Acad Sci U S A 2018; 115:11238-11243. [PMID: 30322937 DOI: 10.1073/pnas.1802967115] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
In 1990, the Seidmans showed that a single point mutation, R403Q, in the human β-myosin heavy chain (MHC) of heart muscle caused a particularly malignant form of familial hypertrophic cardiomyopathy (HCM) [Geisterfer-Lowrance AA, et al. (1990) Cell 62:999-1006.]. Since then, more than 300 mutations in the β-MHC have been reported, and yet there remains a poor understanding of how a single missense mutation in the MYH7 gene can lead to heart disease. Previous studies with a transgenic mouse model showed that the myosin phenotype depended on whether the mutation was in an α- or β-MHC backbone. This led to the generation of a transgenic rabbit model with the R403Q mutation in a β-MHC backbone. We find that the in vitro motility of heterodimeric R403Q myosin is markedly reduced, whereas the actin-activated ATPase activity of R403Q subfragment-1 is about the same as myosin from a nontransgenic littermate. Single myofibrils isolated from the ventricles of R403Q transgenic rabbits and analyzed by atomic force microscopy showed reduced rates of force development and relaxation, and achieved a significantly lower steady-state level of isometric force compared with nontransgenic myofibrils. Myofibrils isolated from the soleus gave similar results. The force-velocity relationship determined for R403Q ventricular myofibrils showed a decrease in the velocity of shortening under load, resulting in a diminished power output. We conclude that independent of whether experiments are performed with isolated molecules or with ordered molecules in the native thick filament of a myofibril, there is a loss-of-function induced by the R403Q mutation in β-cardiac myosin.
Collapse
|
19
|
Brizendine RK, Sheehy GG, Alcala DB, Novenschi SI, Baker JE, Cremo CR. A mixed-kinetic model describes unloaded velocities of smooth, skeletal, and cardiac muscle myosin filaments in vitro. SCIENCE ADVANCES 2017; 3:eaao2267. [PMID: 29255801 PMCID: PMC5733112 DOI: 10.1126/sciadv.aao2267] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Accepted: 11/17/2017] [Indexed: 06/07/2023]
Abstract
In vitro motility assays, where purified myosin and actin move relative to one another, are used to better understand the mechanochemistry of the actomyosin adenosine triphosphatase (ATPase) cycle. We examined the relationship between the relative velocity (V) of actin and myosin and the number of available myosin heads (N) or [ATP] for smooth (SMM), skeletal (SKM), and cardiac (CMM) muscle myosin filaments moving over actin as well as V from actin filaments moving over a bed of monomeric SKM. These data do not fit well to a widely accepted model that predicts that V is limited by myosin detachment from actin (d/ton), where d equals step size and ton equals time a myosin head remains attached to actin. To account for these data, we have developed a mixed-kinetic model where V is influenced by both attachment and detachment kinetics. The relative contributions at a given V vary with the probability that a head will remain attached to actin long enough to reach the end of its flexible S2 tether. Detachment kinetics are affected by L/ton, where L is related to the tether length. We show that L is relatively long for SMM, SKM, and CMM filaments (59 ± 3 nm, 22 ± 9 nm, and 22 ± 2 nm, respectively). In contrast, L is shorter (8 ± 3 nm) when myosin monomers are attached to a surface. This suggests that the behavior of the S2 domain may be an important mechanical feature of myosin filaments that influences unloaded shortening velocities of muscle.
Collapse
|
20
|
Kawas RF, Anderson RL, Ingle SRB, Song Y, Sran AS, Rodriguez HM. A small-molecule modulator of cardiac myosin acts on multiple stages of the myosin chemomechanical cycle. J Biol Chem 2017; 292:16571-16577. [PMID: 28808052 DOI: 10.1074/jbc.m117.776815] [Citation(s) in RCA: 134] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Revised: 08/11/2017] [Indexed: 01/24/2023] Open
Abstract
Mavacamten, formerly known as MYK-461 is a recently discovered novel small-molecule modulator of cardiac myosin that targets the underlying sarcomere hypercontractility of hypertrophic cardiomyopathy, one of the most prevalent heritable cardiovascular disorders. Studies on isolated cells and muscle fibers as well as intact animals have shown that mavacamten inhibits sarcomere force production, thereby reducing cardiac contractility. Initial mechanistic studies have suggested that mavacamten primarily reduces the steady-state ATPase activity by inhibiting the rate of phosphate release of β-cardiac myosin-S1, but the molecular mechanism of action of mavacamten has not been described. Here we used steady-state and presteady-state kinetic analyses to investigate the mechanism of action of mavacamten. Transient kinetic analyses revealed that mavacamten modulates multiple steps of the myosin chemomechanical cycle. In addition to decreasing the rate-limiting step of the cycle (phosphate release), mavacamten reduced the number of myosin-S1 heads that can interact with the actin thin filament during transition from the weakly to the strongly bound state without affecting the intrinsic rate. Mavacamten also decreased the rate of myosin binding to actin in the ADP-bound state and the ADP-release rate from myosin-S1 alone. We, therefore, conclude that mavacamten acts on multiple stages of the myosin chemomechanical cycle. Although the primary mechanism of mavacamten-mediated inhibition of cardiac myosin is the decrease of phosphate release from β-cardiac myosin-S1, a secondary mechanism decreases the number of actin-binding heads transitioning from the weakly to the strongly bound state, which occurs before phosphate release and may provide an additional method to modulate myosin function.
Collapse
Affiliation(s)
- Raja F Kawas
- From MyoKardia, Inc., South San Francisco, California 94080
| | | | | | - Yonghong Song
- From MyoKardia, Inc., South San Francisco, California 94080
| | | | | |
Collapse
|
21
|
Trivedi DV, Adhikari AS, Sarkar SS, Ruppel KM, Spudich JA. Hypertrophic cardiomyopathy and the myosin mesa: viewing an old disease in a new light. Biophys Rev 2017; 10:27-48. [PMID: 28717924 PMCID: PMC5803174 DOI: 10.1007/s12551-017-0274-6] [Citation(s) in RCA: 105] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2017] [Accepted: 06/12/2017] [Indexed: 12/15/2022] Open
Abstract
The sarcomere is an exquisitely designed apparatus that is capable of generating force, which in the case of the heart results in the pumping of blood throughout the body. At the molecular level, an ATP-dependent interaction of myosin with actin drives the contraction and force generation of the sarcomere. Over the past six decades, work on muscle has yielded tremendous insights into the workings of the sarcomeric system. We now stand on the cusp where the acquired knowledge of how the sarcomere contracts and how that contraction is regulated can be extended to an understanding of the molecular mechanisms of sarcomeric diseases, such as hypertrophic cardiomyopathy (HCM). In this review we present a picture that combines current knowledge of the myosin mesa, the sequestered state of myosin heads on the thick filament, known as the interacting-heads motif (IHM), their possible interaction with myosin binding protein C (MyBP-C) and how these interactions can be abrogated leading to hyper-contractility, a key clinical manifestation of HCM. We discuss the structural and functional basis of the IHM state of the myosin heads and identify HCM-causing mutations that can directly impact the equilibrium between the 'on state' of the myosin heads (the open state) and the IHM 'off state'. We also hypothesize a role of MyBP-C in helping to maintain myosin heads in the IHM state on the thick filament, allowing release in a graded manner upon adrenergic stimulation. By viewing clinical hyper-contractility as the result of the destabilization of the IHM state, our aim is to view an old disease in a new light.
Collapse
Affiliation(s)
- Darshan V Trivedi
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA, 94305, USA
| | - Arjun S Adhikari
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA, 94305, USA
| | - Saswata S Sarkar
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA, 94305, USA
| | - Kathleen M Ruppel
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA, 94305, USA. .,Department of Pediatrics (Cardiology), Stanford University School of Medicine, Stanford, CA, 94305, USA.
| | - James A Spudich
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA, 94305, USA.
| |
Collapse
|
22
|
Abstract
Cardiomyopathies represent a heterogeneous group of diseases that negatively affect heart function. Primary cardiomyopathies specifically target the myocardium, and may arise from genetic [hypertrophic cardiomyopathy (HCM), arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D), mitochondrial cardiomyopathy] or genetic and acquired [dilated cardiomyopathy (DCM), restrictive cardiomyopathy (RCM)] etiology. Modern genomics has identified mutations that are common in these populations, while in vitro and in vivo experimentation with these mutations have provided invaluable insight into the molecular mechanisms native to these diseases. For example, increased myosin heavy chain (MHC) binding and ATP utilization lead to the hypercontractile sarcomere in HCM, while abnormal protein–protein interaction and impaired Ca2+ flux underlie the relaxed sarcomere of DCM. Furthermore, expanded access to genetic testing has facilitated identification of potential risk factors that appear through inheritance and manifest sometimes only in the advanced stages of the disease. In this review, we discuss the genetic and molecular abnormalities unique to and shared between these primary cardiomyopathies and discuss some of the important advances made using more traditional basic science experimentation.
Collapse
|
23
|
Garcia J, Tahiliani J, Johnson NM, Aguilar S, Beltran D, Daly A, Decker E, Haverfield E, Herrera B, Murillo L, Nykamp K, Topper S. Clinical Genetic Testing for the Cardiomyopathies and Arrhythmias: A Systematic Framework for Establishing Clinical Validity and Addressing Genotypic and Phenotypic Heterogeneity. Front Cardiovasc Med 2016; 3:20. [PMID: 27446933 PMCID: PMC4921949 DOI: 10.3389/fcvm.2016.00020] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2016] [Accepted: 06/06/2016] [Indexed: 12/19/2022] Open
Abstract
Advances in DNA sequencing have made large, diagnostic gene panels affordable and efficient. Broad adoption of such panels has begun to deliver on the promises of personalized medicine, but has also brought new challenges such as the presence of unexpected results, or results of uncertain clinical significance. Genetic analysis of inherited cardiac conditions is particularly challenging due to the extensive genetic heterogeneity underlying cardiac phenotypes, and the overlapping, variable, and incompletely penetrant nature of their clinical presentations. The design of effective diagnostic tests and the effective use of the results depend on a clear understanding of the relationship between each gene and each considered condition. To address these issues, we developed simple, systematic approaches to three fundamental challenges: (1) evaluating the strength of the evidence suggesting that a particular condition is caused by pathogenic variants in a particular gene, (2) evaluating whether unusual genotype/phenotype observations represent a plausible expansion of clinical phenotype associated with a gene, and (3) establishing a molecular diagnostic strategy to capture overlapping clinical presentations. These approaches focus on the systematic evaluation of the pathogenicity of variants identified in clinically affected individuals, and the natural history of disease in those individuals. Here, we applied these approaches to the evaluation of more than 100 genes reported to be associated with inherited cardiomyopathies and arrhythmias including hypertrophic cardiomyopathy, dilated cardiomyopathy, arrhythmogenic right ventricular dysplasia or cardiomyopathy, long QT syndrome, short QT syndrome, Brugada, and catecholaminergic polymorphic ventricular tachycardia, and to a set of related syndromes such as Noonan Syndrome and Fabry disease. These approaches provide a framework for delivering meaningful and accurate genetic test results to individuals with hereditary cardiac conditions.
Collapse
Affiliation(s)
| | | | | | | | | | - Amy Daly
- Invitae Corporation, San Francisco, CA, USA
| | | | | | | | | | | | | |
Collapse
|
24
|
Birch CL, Behunin SM, Lopez-Pier MA, Danilo C, Lipovka Y, Saripalli C, Granzier H, Konhilas JP. Sex dimorphisms of crossbridge cycling kinetics in transgenic hypertrophic cardiomyopathy mice. Am J Physiol Heart Circ Physiol 2016; 311:H125-36. [PMID: 27199124 DOI: 10.1152/ajpheart.00592.2015] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Accepted: 05/03/2016] [Indexed: 11/22/2022]
Abstract
Familial hypertrophic cardiomyopathy (HCM) is a disease of the sarcomere and may lead to hypertrophic, dilated, restrictive, and/or arrhythmogenic cardiomyopathy, congestive heart failure, or sudden cardiac death. We hypothesized that hearts from transgenic HCM mice harboring a mutant myosin heavy chain increase the energetic cost of contraction in a sex-specific manner. To do this, we assessed Ca(2+) sensitivity of tension and crossbridge kinetics in demembranated cardiac trabeculas from male and female wild-type (WT) and HCM hearts at an early time point (2 mo of age). We found a significant effect of sex on Ca(2+) sensitivity such that male, but not female, HCM mice displayed a decrease in Ca(2+) sensitivity compared with WT counterparts. The HCM transgene and sex significantly impacted the rate of force redevelopment by a rapid release-restretch protocol and tension cost by the ATPase-tension relationship. In each of these measures, HCM male trabeculas displayed a gain-of-function when compared with WT counterparts. In addition, cardiac remodeling measured by echocardiography, histology, morphometry, and posttranslational modifications demonstrated sex- and HCM-specific effects. In conclusion, female and male HCM mice display sex dimorphic crossbridge kinetics accompanied by sex- and HCM-dependent cardiac remodeling at the morphometric, histological, and cellular level.
Collapse
Affiliation(s)
- Camille L Birch
- Sarver Molecular Cardiovascular Research Program, University of Arizona, Tucson, Arizona; Department of Biomedical Engineering, University of Arizona, Tucson, Arizona
| | - Samantha M Behunin
- Department of Physiology, University of Arizona, Tucson, Arizona; Sarver Molecular Cardiovascular Research Program, University of Arizona, Tucson, Arizona
| | - Marissa A Lopez-Pier
- Sarver Molecular Cardiovascular Research Program, University of Arizona, Tucson, Arizona; Department of Biomedical Engineering, University of Arizona, Tucson, Arizona
| | - Christiane Danilo
- Department of Physiology, University of Arizona, Tucson, Arizona; Sarver Molecular Cardiovascular Research Program, University of Arizona, Tucson, Arizona
| | - Yulia Lipovka
- Sarver Molecular Cardiovascular Research Program, University of Arizona, Tucson, Arizona; Department of Molecular and Cellular Biology, University of Arizona, Tucson, Arizona; and
| | - Chandra Saripalli
- Sarver Molecular Cardiovascular Research Program, University of Arizona, Tucson, Arizona; Department of Cellular and Molecular Medicine, University of Arizona, Tucson, Arizona
| | - Henk Granzier
- Sarver Molecular Cardiovascular Research Program, University of Arizona, Tucson, Arizona; Department of Cellular and Molecular Medicine, University of Arizona, Tucson, Arizona
| | - John P Konhilas
- Department of Physiology, University of Arizona, Tucson, Arizona; Sarver Molecular Cardiovascular Research Program, University of Arizona, Tucson, Arizona;
| |
Collapse
|
25
|
Nag S, Sommese RF, Ujfalusi Z, Combs A, Langer S, Sutton S, Leinwand LA, Geeves MA, Ruppel KM, Spudich JA. Contractility parameters of human β-cardiac myosin with the hypertrophic cardiomyopathy mutation R403Q show loss of motor function. SCIENCE ADVANCES 2015; 1:e1500511. [PMID: 26601291 PMCID: PMC4646805 DOI: 10.1126/sciadv.1500511] [Citation(s) in RCA: 82] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2015] [Accepted: 08/17/2015] [Indexed: 05/20/2023]
Abstract
Hypertrophic cardiomyopathy (HCM) is the most frequently occurring inherited cardiovascular disease. It is caused by mutations in genes encoding the force-generating machinery of the cardiac sarcomere, including human β-cardiac myosin. We present a detailed characterization of the most debated HCM-causing mutation in human β-cardiac myosin, R403Q. Despite numerous studies, most performed with nonhuman or noncardiac myosin, there is no consensus about the mechanism of action of this mutation on the function of the enzyme. We use recombinant human β-cardiac myosin and new methodologies to characterize in vitro contractility parameters of the R403Q myosin compared to wild type. We extend our studies beyond pure actin filaments to include the interaction of myosin with regulated actin filaments containing tropomyosin and troponin. We find that, with pure actin, the intrinsic force generated by R403Q is ~15% lower than that generated by wild type. The unloaded velocity is, however, ~10% higher for R403Q myosin, resulting in a load-dependent velocity curve that has the characteristics of lower contractility at higher external loads compared to wild type. With regulated actin filaments, there is no increase in the unloaded velocity and the contractility of the R403Q myosin is lower than that of wild type at all loads. Unlike that with pure actin, the actin-activated adenosine triphosphatase activity for R403Q myosin with Ca(2+)-regulated actin filaments is ~30% lower than that for wild type, predicting a lower unloaded duty ratio of the motor. Overall, the contractility parameters studied fit with a loss of human β-cardiac myosin contractility as a result of the R403Q mutation.
Collapse
Affiliation(s)
- Suman Nag
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Ruth F. Sommese
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Zoltan Ujfalusi
- School of Biosciences, University of Kent, Canterbury CT2 7NJ, UK
| | - Ariana Combs
- Department of Molecular, Cellular and Developmental Biology, BioFrontiers Institute, University of Colorado, Boulder, CO 80309, USA
| | - Stephen Langer
- Department of Molecular, Cellular and Developmental Biology, BioFrontiers Institute, University of Colorado, Boulder, CO 80309, USA
| | - Shirley Sutton
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Leslie A. Leinwand
- Department of Molecular, Cellular and Developmental Biology, BioFrontiers Institute, University of Colorado, Boulder, CO 80309, USA
| | | | - Kathleen M. Ruppel
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA
- Department of Pediatrics (Cardiology), Stanford University School of Medicine, Stanford, CA 94305, USA
| | - James A. Spudich
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA
| |
Collapse
|
26
|
Aksel T, Choe Yu E, Sutton S, Ruppel KM, Spudich JA. Ensemble force changes that result from human cardiac myosin mutations and a small-molecule effector. Cell Rep 2015; 11:910-920. [PMID: 25937279 PMCID: PMC4431957 DOI: 10.1016/j.celrep.2015.04.006] [Citation(s) in RCA: 83] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Revised: 03/19/2015] [Accepted: 04/01/2015] [Indexed: 11/24/2022] Open
Abstract
Cardiomyopathies due to mutations in human β-cardiac myosin are a significant cause of heart failure, sudden death, and arrhythmia. To understand the underlying molecular basis of changes in the contractile system's force production due to such mutations and search for potential drugs that restore force generation, an in vitro assay is necessary to evaluate cardiac myosin's ensemble force using purified proteins. Here, we characterize the ensemble force of human α- and β-cardiac myosin isoforms and those of β-cardiac myosins carrying left ventricular non-compaction (M531R) and dilated cardiomyopathy (S532P) mutations using a utrophin-based loaded in vitro motility assay and new filament-tracking software. Our results show that human α- and β-cardiac myosin, as well as the mutants, show opposite mechanical and enzymatic phenotypes with respect to each other. We also show that omecamtiv mecarbil, a previously discovered cardiac-specific myosin activator, increases β-cardiac myosin force generation.
Collapse
Affiliation(s)
- Tural Aksel
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Elizabeth Choe Yu
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA; Cancer Biology Program, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Shirley Sutton
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Kathleen M Ruppel
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Pediatrics (Cardiology), Stanford University School of Medicine, Stanford, CA 94305, USA.
| | - James A Spudich
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA.
| |
Collapse
|
27
|
Colegrave M, Peckham M. Structural implications of β-cardiac myosin heavy chain mutations in human disease. Anat Rec (Hoboken) 2015; 297:1670-80. [PMID: 25125180 DOI: 10.1002/ar.22973] [Citation(s) in RCA: 79] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Revised: 04/09/2014] [Accepted: 04/09/2014] [Indexed: 12/11/2022]
Abstract
Over 500 disease-causing point mutations have been found in the human β-cardiac myosin heavy chain, many quite recently with modern sequencing techniques. This review shows that clusters of these mutations occur at critical points in the sequence and investigates whether the many studies on these mutants reveal information about the function of this protein.
Collapse
Affiliation(s)
- Melanie Colegrave
- Faculty of Biological Sciences, School of Molecular and Cellular Biology, University of Leeds, Leeds LS2 9JT, United Kingdom
| | | |
Collapse
|
28
|
Witjas-Paalberends ER, Ferrara C, Scellini B, Piroddi N, Montag J, Tesi C, Stienen GJM, Michels M, Ho CY, Kraft T, Poggesi C, van der Velden J. Faster cross-bridge detachment and increased tension cost in human hypertrophic cardiomyopathy with the R403Q MYH7 mutation. J Physiol 2014; 592:3257-72. [PMID: 24928957 DOI: 10.1113/jphysiol.2014.274571] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
The first mutation associated with hypertrophic cardiomyopathy (HCM) is the R403Q mutation in the gene encoding β-myosin heavy chain (β-MyHC). R403Q locates in the globular head of myosin (S1), responsible for interaction with actin, and thus motor function of myosin. Increased cross-bridge relaxation kinetics caused by the R403Q mutation might underlie increased energetic cost of tension generation; however, direct evidence is absent. Here we studied to what extent cross-bridge kinetics and energetics are related in single cardiac myofibrils and multicellular cardiac muscle strips of three HCM patients with the R403Q mutation and nine sarcomere mutation-negative HCM patients (HCMsmn). Expression of R403Q was on average 41 ± 4% of total MYH7 mRNA. Cross-bridge slow relaxation kinetics in single R403Q myofibrils was significantly higher (P < 0.0001) than in HCMsmn myofibrils (0.47 ± 0.02 and 0.30 ± 0.02 s(-1), respectively). Moreover, compared to HCMsmn, tension cost was significantly higher in the muscle strips of the three R403Q patients (2.93 ± 0.25 and 1.78 ± 0.10 μmol l(-1) s(-1) kN(-1) m(-2), respectively) which showed a positive linear correlation with relaxation kinetics in the corresponding myofibril preparations. This correlation suggests that faster cross-bridge relaxation kinetics results in an increase in energetic cost of tension generation in human HCM with the R403Q mutation compared to HCMsmn. Therefore, increased tension cost might contribute to HCM disease in patients carrying the R403Q mutation.
Collapse
Affiliation(s)
| | - Claudia Ferrara
- Department of Experimental and Clinical Medicine, University of Florence, Florence, Italy
| | - Beatrice Scellini
- Department of Experimental and Clinical Medicine, University of Florence, Florence, Italy
| | - Nicoletta Piroddi
- Department of Experimental and Clinical Medicine, University of Florence, Florence, Italy
| | - Judith Montag
- Institute of Molecular and Cell Physiology, Hannover Medical School, Hannover, Germany
| | - Chiara Tesi
- Department of Experimental and Clinical Medicine, University of Florence, Florence, Italy
| | - Ger J M Stienen
- Department of Physiology, VU University Medical Centre, Amsterdam, The Netherlands Department of Physics and Astronomy, VU University, Amsterdam, The Netherlands
| | - Michelle Michels
- Thorax Centre, Cardiology, Erasmus Medical Centre, Rotterdam, The Netherlands
| | - Carolyn Y Ho
- Brigham and Women's Hospital, Cardiology, Boston, USA
| | - Theresia Kraft
- Institute of Molecular and Cell Physiology, Hannover Medical School, Hannover, Germany
| | - Corrado Poggesi
- Department of Experimental and Clinical Medicine, University of Florence, Florence, Italy
| | - Jolanda van der Velden
- Department of Physiology, VU University Medical Centre, Amsterdam, The Netherlands ICIN-Netherlands Heart Institute, Utrecht, The Netherlands
| |
Collapse
|
29
|
Abraham MR, Bottomley PA, Dimaano VL, Pinheiro A, Steinberg A, Traill TA, Abraham TP, Weiss RG. Creatine kinase adenosine triphosphate and phosphocreatine energy supply in a single kindred of patients with hypertrophic cardiomyopathy. Am J Cardiol 2013; 112:861-6. [PMID: 23751935 DOI: 10.1016/j.amjcard.2013.05.017] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/07/2013] [Revised: 05/02/2013] [Accepted: 05/02/2013] [Indexed: 01/20/2023]
Abstract
A lethal and extensively characterized familial form of hypertrophic cardiomyopathy (HC) is due to a point mutation (Arg403Gln) in the cardiac β-myosin heavy chain gene. Although this is associated with abnormal energy metabolism and progression to heart failure in an animal model, in vivo cardiac energetics have not been characterized in patients with this mutation. Noninvasive phosphorus saturation transfer magnetic resonance spectroscopy was used to measure the adenosine triphosphate supplied by the creatine kinase (CK) reaction and phosphocreatine, the heart's primary energy reserve, in 9 of 10 patients from a single kindred with HC caused by the Arg403GIn mutation and 17 age-matched healthy controls. Systolic and diastolic function was assessed by echocardiography in all 10 patients with HC. The patients with HC had impairment of diastolic function and mild systolic dysfunction, when assessed using global systolic longitudinal strain. Myocardial phosphocreatine was significantly decreased by 24% in patients (7.1 ± 2.3 μmol/g) compared with the controls (9.4 ± 1.2 μmol/g; p = 0.003). The pseudo-first-order CK rate-constant was 26% lower (0.28 ± 0.15 vs 0.38 ± 0.07 s⁻¹, p = 0.035) and the forward CK flux was 44% lower (2.0 ± 1.4 vs 3.6 ± 0.9 μmol/g/s, p = 0.001) than in the controls. The contractile abnormalities did not correlate with the metabolic indexes. In conclusion, myocardial phosphocreatine and CK-ATP delivery are significantly reduced in patients with HC caused by the Arg403Gln mutation, akin to previous results from mice with the same mutation. A lack of a relation between energetic and contractile abnormalities suggests the former result from the sarcomeric mutation and not a late consequence of mechanical dysfunction.
Collapse
|
30
|
McKee LA, Chen H, Regan JA, Behunin SM, Walker JW, Walker JS, Konhilas JP. Sexually dimorphic myofilament function and cardiac troponin I phosphospecies distribution in hypertrophic cardiomyopathy mice. Arch Biochem Biophys 2013; 535:39-48. [PMID: 23352598 PMCID: PMC3640654 DOI: 10.1016/j.abb.2012.12.023] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2012] [Revised: 12/12/2012] [Accepted: 12/14/2012] [Indexed: 11/16/2022]
Abstract
The pathological progression of hypertrophic cardiomyopathy (HCM) is sexually dimorphic such that male HCM mice develop phenotypic indicators of cardiac disease well before female HCM mice. Here, we hypothesized that alterations in myofilament function underlies, in part, this sex dimorphism in HCM disease development. Firstly, 10-12month female HCM (harboring a mutant [R403Q] myosin heavy chain) mice presented with proportionately larger hearts than male HCM mice. Next, we determined Ca(2+)-sensitive tension development in demembranated cardiac trabeculae excised from 10-12month female and male HCM mice. Whereas HCM did not impact Ca(2+)-sensitive tension development in male trabeculae, female HCM trabeculae were more sensitive to Ca(2+) than wild-type (WT) counterparts and both WT and HCM males. We hypothesized that the underlying cause of this sex difference in Ca(2+)-sensitive tension development was due to changes in Ca(2+) handling and sarcomeric proteins, including expression of SR Ca(2+) ATPase (2a) (SERCA2a), β-myosin heavy chain (β-MyHC) and post-translational modifications of myofilament proteins. Female HCM hearts showed an elevation of SERCA2a and β-MyHC protein whereas male HCM hearts showed a similar elevation of β-MyHC protein but a reduced level of cardiac troponin T (cTnT) phosphorylation. We also measured the distribution of cardiac troponin I (cTnI) phosphospecies using phosphate-affinity SDS-PAGE. The distribution of cTnI phosphospecies depended on sex and HCM. In conclusion, female and male HCM mice display sex dimorphic myofilament function that is accompanied by a sex- and HCM-dependent distribution of sarcomeric proteins and cTnI phosphospecies.
Collapse
Affiliation(s)
- Laurel A.K. McKee
- Department of Physiology, Sarver Molecular Cardiovascular Research Program, University of Arizona, 1501 N. Campbell Ave., Tucson, AZ 85724, USA
| | - Hao Chen
- Department of Physiology, Sarver Molecular Cardiovascular Research Program, University of Arizona, 1501 N. Campbell Ave., Tucson, AZ 85724, USA
| | - Jessica A. Regan
- Department of Physiology, Sarver Molecular Cardiovascular Research Program, University of Arizona, 1501 N. Campbell Ave., Tucson, AZ 85724, USA
| | - Samantha M. Behunin
- Department of Physiology, Sarver Molecular Cardiovascular Research Program, University of Arizona, 1501 N. Campbell Ave., Tucson, AZ 85724, USA
| | - Jeffery W. Walker
- Department of Physiology, Sarver Molecular Cardiovascular Research Program, University of Arizona, 1501 N. Campbell Ave., Tucson, AZ 85724, USA
| | - John S. Walker
- University of Colorado Denver, Department of Medicine/Cardiology, Aurora, CO 80045, USA
| | - John P. Konhilas
- Department of Physiology, Sarver Molecular Cardiovascular Research Program, University of Arizona, 1501 N. Campbell Ave., Tucson, AZ 85724, USA
| |
Collapse
|
31
|
Molecular consequences of the R453C hypertrophic cardiomyopathy mutation on human β-cardiac myosin motor function. Proc Natl Acad Sci U S A 2013; 110:12607-12. [PMID: 23798412 DOI: 10.1073/pnas.1309493110] [Citation(s) in RCA: 136] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Cardiovascular disorders are the leading cause of morbidity and mortality in the developed world, and hypertrophic cardiomyopathy (HCM) is among the most frequently occurring inherited cardiac disorders. HCM is caused by mutations in the genes encoding the fundamental force-generating machinery of the cardiac muscle, including β-cardiac myosin. Here, we present a biomechanical analysis of the HCM-causing mutation, R453C, in the context of human β-cardiac myosin. We found that this mutation causes a ∼30% decrease in the maximum ATPase of the human β-cardiac subfragment 1, the motor domain of myosin, and a similar percent decrease in the in vitro velocity. The major change in the R453C human β-cardiac subfragment 1 is a 50% increase in the intrinsic force of the motor compared with wild type, with no appreciable change in the stroke size, as observed with a dual-beam optical trap. These results predict that the overall force of the ensemble of myosin molecules in the muscle should be higher in the R453C mutant compared with wild type. Loaded in vitro motility assay confirms that the net force in the ensemble is indeed increased. Overall, this study suggests that the R453C mutation should result in a hypercontractile state in the heart muscle.
Collapse
|
32
|
Witjas-Paalberends ER, Piroddi N, Stam K, van Dijk SJ, Oliviera VS, Ferrara C, Scellini B, Hazebroek M, ten Cate FJ, van Slegtenhorst M, dos Remedios C, Niessen HWM, Tesi C, Stienen GJM, Heymans S, Michels M, Poggesi C, van der Velden J. Mutations in MYH7 reduce the force generating capacity of sarcomeres in human familial hypertrophic cardiomyopathy. Cardiovasc Res 2013; 99:432-41. [PMID: 23674513 DOI: 10.1093/cvr/cvt119] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
AIMS Familial hypertrophic cardiomyopathy (HCM), frequently caused by sarcomeric gene mutations, is characterized by cellular dysfunction and asymmetric left-ventricular (LV) hypertrophy. We studied whether cellular dysfunction is due to an intrinsic sarcomere defect or cardiomyocyte remodelling. METHODS AND RESULTS Cardiac samples from 43 sarcomere mutation-positive patients (HCMmut: mutations in thick (MYBPC3, MYH7) and thin (TPM1, TNNI3, TNNT2) myofilament genes) were compared with 14 sarcomere mutation-negative patients (HCMsmn), eight patients with secondary LV hypertrophy due to aortic stenosis (LVHao) and 13 donors. Force measurements in single membrane-permeabilized cardiomyocytes revealed significantly lower maximal force generating capacity (Fmax) in HCMmut (21 ± 1 kN/m²) and HCMsmn (26 ± 3 kN/m²) compared with donor (36 ± 2 kN/m²). Cardiomyocyte remodelling was more severe in HCMmut compared with HCMsmn based on significantly lower myofibril density (49 ± 2 vs. 63 ± 5%) and significantly higher cardiomyocyte area (915 ± 15 vs. 612 ± 11 μm²). Low Fmax in MYBPC3mut, TNNI3mut, HCMsmn, and LVHao was normalized to donor values after correction for myofibril density. However, Fmax was significantly lower in MYH7mut, TPM1mut, and TNNT2mut even after correction for myofibril density. In accordance, measurements in single myofibrils showed very low Fmax in MYH7mut, TPM1mut, and TNNT2mut compared with donor (respectively, 73 ± 3, 70 ± 7, 83 ± 6, and 113 ± 5 kN/m²). In addition, force was lower in MYH7mut cardiomyocytes compared with MYBPC3mut, HCMsmn, and donor at submaximal [Ca²⁺]. CONCLUSION Low cardiomyocyte Fmax in HCM patients is largely explained by hypertrophy and reduced myofibril density. MYH7 mutations reduce force generating capacity of sarcomeres at maximal and submaximal [Ca²⁺]. These hypocontractile sarcomeres may represent the primary abnormality in patients with MYH7 mutations.
Collapse
Affiliation(s)
- E Rosalie Witjas-Paalberends
- Laboratory for Physiology, VU University Medical Center, Institute for Cardiovascular Research, Van der Boechorststraat 7, 1081 BT Amsterdam, The Netherlands.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
33
|
Lowey S, Bretton V, Gulick J, Robbins J, Trybus KM. Transgenic mouse α- and β-cardiac myosins containing the R403Q mutation show isoform-dependent transient kinetic differences. J Biol Chem 2013; 288:14780-7. [PMID: 23580644 DOI: 10.1074/jbc.m113.450668] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Familial hypertrophic cardiomyopathy (FHC) is a major cause of sudden cardiac death in young athletes. The discovery in 1990 that a point mutation at residue 403 (R403Q) in the β-myosin heavy chain (MHC) caused a severe form of FHC was the first of many demonstrations linking FHC to mutations in muscle proteins. A mouse model for FHC has been widely used to study the mechanochemical properties of mutated cardiac myosin, but mouse hearts express α-MHC, whereas the ventricles of larger mammals express predominantly β-MHC. To address the role of the isoform backbone on function, we generated a transgenic mouse in which the endogenous α-MHC was partially replaced with transgenically encoded β-MHC or α-MHC. A His6 tag was cloned at the N terminus, along with R403Q, to facilitate isolation of myosin subfragment 1 (S1). Stopped flow kinetics were used to measure the equilibrium constants and rates of nucleotide binding and release for the mouse S1 isoforms bound to actin. For the wild-type isoforms, we found that the affinity of MgADP for α-S1 (100 μM) is ~ 4-fold weaker than for β-S1 (25 μM). Correspondingly, the MgADP release rate for α-S1 (350 s(-1)) is ~3-fold greater than for β-S1 (120 s(-1)). Introducing the R403Q mutation caused only a minor reduction in kinetics for β-S1, but R403Q in α-S1 caused the ADP release rate to increase by 20% (430 s(-1)). These transient kinetic studies on mouse cardiac myosins provide strong evidence that the functional impact of an FHC mutation on myosin depends on the isoform backbone.
Collapse
Affiliation(s)
- Susan Lowey
- Department of Molecular Physiology and Biophysics, University of Vermont, Burlington, Vermont 05405, USA.
| | | | | | | | | |
Collapse
|
34
|
Kraft T, Witjas-Paalberends ER, Boontje NM, Tripathi S, Brandis A, Montag J, Hodgkinson JL, Francino A, Navarro-Lopez F, Brenner B, Stienen GJM, van der Velden J. Familial hypertrophic cardiomyopathy: functional effects of myosin mutation R723G in cardiomyocytes. J Mol Cell Cardiol 2013; 57:13-22. [PMID: 23318932 DOI: 10.1016/j.yjmcc.2013.01.001] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/10/2012] [Accepted: 01/03/2013] [Indexed: 11/17/2022]
Abstract
Familial Hypertrophic Cardiomyopathy (FHC) is frequently caused by mutations in the β-cardiac myosin heavy chain (β-MyHC). To identify changes in sarcomeric function triggered by such mutations, distinguishing mutation effects from other functional alterations of the myocardium is essential. We previously identified a direct effect of mutation R723G (MyHC723) on myosin function in slow Musculus soleus fibers. Here we investigate contractile features of left ventricular cardiomyocytes of FHC-patients with the same MyHC723-mutation and compare these to the soleus data. In mechanically isolated, triton-permeabilized MyHC723-cardiomyocytes, maximum force was significantly lower but calcium-sensitivity was unchanged compared to donor. Conversely, MyHC723-soleus fibers showed significantly higher maximum force and reduced calcium-sensitivity compared to controls. Protein phosphorylation, a potential myocardium specific modifying mechanism, might account for differences compared to soleus fibers. Analysis revealed reduced phosphorylation of troponin I and T, myosin-binding-protein C, and myosin-light-chain 2 in MyHC723-myocardium compared to donor. Saturation of protein-kinaseA phospho-sites led to comparable, i.e., reduced MyHC723-calcium-sensitivity in cardiomyocytes as in M. soleus fibers, while maximum force remained reduced. Myofibrillar disarray and lower density of myofibrils, however, largely account for reduced maximum force in MyHC723-cardiomyocytes. The changes seen when phosphorylation of sarcomeric proteins in myocardium of affected patients is matched to control tissue suggest that the R723G mutation causes reduced Ca(++)-sensitivity in both cardiomyocytes and M. soleus fibers. In MyHC723-myocardium, however, hypophosphorylation can compensate for the reduced calcium-sensitivity, while maximum force generation, lowered by myofibrillar deficiency and disarray, remains impaired, and may only be compensated by hypertrophy.
Collapse
Affiliation(s)
- Theresia Kraft
- Molecular and Cell Physiology, Hannover Medical School, D-30625 Hannover, Germany.
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
35
|
Di Domenico M, Casadonte R, Ricci P, Santini M, Frati G, Rizzo A, Carratelli CR, Lamberti M, Parrotta E, Quaresima B, Faniello CM, Costanzo F, Cuda G. Cardiac and skeletal muscle expression of mutant β-myosin heavy chains, degree of functional impairment and phenotypic heterogeneity in hypertrophic cardiomyopathy. J Cell Physiol 2012; 227:3471-6. [PMID: 22213221 DOI: 10.1002/jcp.24047] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Several mutations in distinct genes, all coding for sarcomeric proteins, have been reported in unrelated kindreds with familial hypertrophic cardiomyopathy (FHC). We have identified nine individuals from three families harboring two distinct mutations in one copy of the β-myosin heavy chain (β-MHC) gene. In this study, the expression of the mutant β-myosin protein isoform, isolated from slow-twitch fibers of skeletal muscle, was demonstrated by Northern and Western blot analysis; this myosin showed a decreased in vitro motility activity and produced a lower actin-activated ATPase activity. Isometric tension, measured in single slow-twitch fibers isolated from the affected individuals, also showed a significant decrease. The degree of impairment of β-myosin function, as well as the loss in isometric tension development, were strictly dependent on the amount of the isoform transcribed from the mutated allele. Interestingly, a strong correlation was also demonstrated between mutant β-myosin content and clinical features of FHC. On the other hand, we were unable to detect any correlation between mutant β-myosin expression and degree of cardiac hypertrophy, thereby strengthening the hypothesis that hypertrophy, one of the hallmarks of FHC, might not necessarily be related to the clinical evolution of this disease. These findings lend support to the notion that additional factors rather than the mutated gene may play a pathogenetic role in cardiac wall thickening, whereas the prognosis appears to be strongly related to the amount of mutant protein.
Collapse
|
36
|
Moore JR, Leinwand L, Warshaw DM. Understanding cardiomyopathy phenotypes based on the functional impact of mutations in the myosin motor. Circ Res 2012; 111:375-85. [PMID: 22821910 DOI: 10.1161/circresaha.110.223842] [Citation(s) in RCA: 147] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Hypertrophic (HCM) and dilated (DCM) cardiomyopathies are inherited diseases with a high incidence of death due to electric abnormalities or outflow tract obstruction. In many of the families afflicted with either disease, causative mutations have been identified in various sarcomeric proteins. In this review, we focus on mutations in the cardiac muscle molecular motor, myosin, and its associated light chains. Despite the >300 identified mutations, there is still no clear understanding of how these mutations within the same myosin molecule can lead to the dramatically different clinical phenotypes associated with HCM and DCM. Localizing mutations within myosin's molecular structure provides insight into the potential consequence of these perturbations to key functional domains of the motor. Review of biochemical and biophysical data that characterize the functional capacities of these mutant myosins suggests that mutant myosins with enhanced contractility lead to HCM, whereas those displaying reduced contractility lead to DCM. With gain and loss of function potentially being the primary consequence of a specific mutation, how these functional changes trigger the hypertrophic response and lead to the distinct HCM and DCM phenotypes will be the future investigative challenge.
Collapse
Affiliation(s)
- Jeffrey R Moore
- Department of Physiology and Biophysics, Boston University School of Medicine, Boston, MA 02118, USA.
| | | | | |
Collapse
|
37
|
Chuan P, Sivaramakrishnan S, Ashley EA, Spudich JA. Cell-intrinsic functional effects of the α-cardiac myosin Arg-403-Gln mutation in familial hypertrophic cardiomyopathy. Biophys J 2012; 102:2782-90. [PMID: 22735528 DOI: 10.1016/j.bpj.2012.04.049] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2011] [Revised: 04/02/2012] [Accepted: 04/13/2012] [Indexed: 01/27/2023] Open
Abstract
Human familial hypertrophic cardiomyopathy is the most common Mendelian cardiovascular disease worldwide. Among the most severe presentations of the disease are those in families heterozygous for the mutation R403Q in β-cardiac myosin. Mice heterozygous for this mutation in the α-cardiac myosin isoform display typical familial hypertrophic cardiomyopathy pathology. Here, we study cardiomyocytes from heterozygous 403/+ mice. The effects of the R403Q mutation on force-generating capabilities and dynamics of cardiomyocytes were investigated using a dual carbon nanofiber technique to measure single-cell parameters. We demonstrate the Frank-Starling effect at the single cardiomyocyte level by showing that cell stretch causes an increase in amplitude of contraction. Mutant 403/+ cardiomyocytes exhibit higher end-diastolic and end-systolic stiffness than +/+ cardiomyocytes, whereas active force generation capabilities remain unchanged. Additionally, 403/+ cardiomyocytes show slowed relaxation dynamics. These phenotypes are consistent with increased end-diastolic and end-systolic chamber elastance, as well as diastolic dysfunction seen at the level of the whole heart. Our results show that these functional effects of the R403Q mutation are cell-intrinsic, a property that may be a general phenomenon in familial hypertrophic cardiomyopathy.
Collapse
Affiliation(s)
- Peiying Chuan
- Department of Biochemistry, Stanford University School of Medicine, Stanford, California, USA
| | | | | | | |
Collapse
|
38
|
Capek P, Vondrasek J, Skvor J, Brdicka R. Hypertrophic cardiomyopathy: from mutation to functional analysis of defective protein. Croat Med J 2012; 52:384-91. [PMID: 21674835 PMCID: PMC3118724 DOI: 10.3325/cmj.2011.52.384] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Aim To analyze the genesis of hypertrophic cardiomyopathy on a large cohort of patients from molecular genetics point of view and perform the functional analysis of the 3D molecular model of defective myosin-7 protein in silico. Methods The study enrolled 153 patients with diagnosed hypertrophic cardiomyopathy from different parts of the Czech Republic. DNA samples were analyzed for mutations in exons 21 and 22 of the MYH7 gene, which have been associated with high mutation clustering. The 3D model of human myosin-7 was built using the x-ray structure of nucleotide-free scallop myosin S1 as the structural template. We performed de novo structure prediction of mutant and wild type peptides spanning the 769-788 amino acids region of the myosin-7 protein. Results The Arg870His and Asp778Val amino acid alterations were found in 2 unrelated patients with a severe form of hypertrophic cardiomyopathy. The Asp778Val variation was chosen for subsequent 3D molecular modeling in silico. The mutation of the Asp by Val not only changes the character of the interaction pattern with other amino acids or ions but Val, being a small hydrophobic amino acid, can also completely change the stability of the region. Conclusion Mutation location in the MYH7 gene and changes in amino acid composition may have a crucial negative impact on the outcome of the disease in patients with hypertrophic cardiomyopathy. In addition, a mutation that changes the charge of the amino acid is more likely to affect protein function than a conservative mutation.
Collapse
Affiliation(s)
- Pavel Capek
- Department of Anthropology and Human Genetics, Charles University, Prague, Czech Republic.
| | | | | | | |
Collapse
|
39
|
Barry SP, Townsend PA. What causes a broken heart--molecular insights into heart failure. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2011; 284:113-79. [PMID: 20875630 DOI: 10.1016/s1937-6448(10)84003-1] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Our understanding of the molecular processes which regulate cardiac function has grown immeasurably in recent years. Even with the advent of β-blockers, angiotensin inhibitors and calcium modulating agents, heart failure (HF) still remains a seriously debilitating and life-threatening condition. Here, we review the molecular changes which occur in the heart in response to increased load and the pathways which control cardiac hypertrophy, calcium homeostasis, and immune activation during HF. These can occur as a result of genetic mutation in the case of hypertrophic cardiomyopathy (HCM) and dilated cardiomyopathy (DCM) or as a result of ischemic or hypertensive heart disease. In the majority of cases, calcineurin and CaMK respond to dysregulated calcium signaling and adrenergic drive is increased, each of which has a role to play in controlling blood pressure, heart rate, and left ventricular function. Many major pathways for pathological remodeling converge on a set of transcriptional regulators such as myocyte enhancer factor 2 (MEF2), nuclear factors of activated T cells (NFAT), and GATA4 and these are opposed by the action of the natriuretic peptides ANP and BNP. Epigenetic modification has emerged in recent years as a major influence cardiac physiology and histone acetyl transferases (HATs) and histone deacetylases (HDACs) are now known to both induce and antagonize hypertrophic growth. The newly emerging roles of microRNAs in regulating left ventricular dysfunction and fibrosis also has great potential for novel therapeutic intervention. Finally, we discuss the role of the immune system in mediating left ventricular dysfunction and fibrosis and ways this can be targeted in the setting of viral myocarditis.
Collapse
Affiliation(s)
- Seán P Barry
- Institute of Molecular Medicine, St. James's Hospital, Trinity College Dublin, Dublin 8, Ireland
| | | |
Collapse
|
40
|
Modeling smooth muscle myosin's two heads: long-lived enzymatic roles and phosphorylation-dependent equilibria. Biophys J 2010; 99:1129-38. [PMID: 20712996 DOI: 10.1016/j.bpj.2010.06.018] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2010] [Revised: 06/07/2010] [Accepted: 06/11/2010] [Indexed: 11/21/2022] Open
Abstract
Smooth muscle myosin has two heads, each capable of interacting with actin to generate force and/or motion as it hydrolyzes ATP. These heads are inhibited when their associated regulatory light chain is unphosphorylated (0P), becoming active and hydrolyzing ATP maximally when phosphorylated (2P). Interestingly, with only one of the two regulatory light chains phosphorylated (1P), smooth muscle myosin is active but its ATPase rate is <2P. To explain published 1P single ATP turnover and steady-state ATPase activities, we propose a kinetic model in which 1P myosin exists in an equilibrium between being fully active (2P) and inhibited (0P). Based on the single ATP turnover data, we also propose that each 2P head adopts a hydrolytic role distinct from its partner at any point in time, i.e., one head strongly binds actin and hydrolyzes ATP at its actin-activated rate while the other weakly binds actin. Surprisingly, the heads switch roles slowly (<0.1 s(-1)), suggesting that their activities are not independent. The phosphorylation-dependent equilibrium between active and inhibited states and the hydrolytic role that each head adopts during its interaction with actin may have implications for understanding regulation and mechanical performance of other members of the myosin family of molecular motors.
Collapse
|
41
|
Rohini A, Agrawal N, Koyani CN, Singh R. Molecular targets and regulators of cardiac hypertrophy. Pharmacol Res 2010; 61:269-80. [DOI: 10.1016/j.phrs.2009.11.012] [Citation(s) in RCA: 203] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2009] [Revised: 11/29/2009] [Accepted: 11/30/2009] [Indexed: 02/08/2023]
|
42
|
Rescue of familial cardiomyopathies by modifications at the level of sarcomere and Ca2+ fluxes. J Mol Cell Cardiol 2010; 48:834-42. [PMID: 20079744 DOI: 10.1016/j.yjmcc.2010.01.003] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/02/2009] [Revised: 12/30/2009] [Accepted: 01/06/2010] [Indexed: 12/21/2022]
Abstract
Cardiomyopathies are a heterogeneous group of diseases of the myocardium associated with mechanical and/or electrical dysfunction that frequently show inappropriate ventricular hypertrophy or dilation. Current data suggest that numerous mutations in several genes can cause cardiomyopathies, and the severity of their phenotypes is also influenced by modifier genes. Two major types of inherited cardiomyopathies include familial hypertrophic cardiomyopathy (FHC) and dilated cardiomyopathy (DCM). FHC typically involves increased myofilament Ca(2+) sensitivity associated with diastolic dysfunction, whereas DCM often results in decreased myofilament Ca(2+) sensitivity and systolic dysfunction. Besides alterations in myofilament Ca(2+) sensitivity, alterations in the levels of Ca(2+)-handling proteins have also been described in both diseases. Recent work in animal models has attempted to rescue FHC and DCM via modifications at the myofilament level, altering Ca(2+) homeostasis by targeting Ca(2+)-handling proteins, such as the sarcoplasmic reticulum ATPase and phospholamban, or by interfering with the products of different modifiers genes. Although attempts to rescue cardiomyopathies in animal models have shown great promise, further studies are needed to validate these strategies in order to provide more effective and specific treatments.
Collapse
|
43
|
Sivaramakrishnan S, Ashley E, Leinwand L, Spudich JA. Insights into human beta-cardiac myosin function from single molecule and single cell studies. J Cardiovasc Transl Res 2009; 2:426-40. [PMID: 20560001 DOI: 10.1007/s12265-009-9129-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/22/2009] [Accepted: 09/10/2009] [Indexed: 12/13/2022]
Abstract
beta-Cardiac myosin is a mechanoenzyme that converts the energy from ATP hydrolysis into a mechanical force that drives contractility in muscle. Thirty percent of the point mutations that result in hypertrophic cardiomyopathy are localized to MYH7, the gene encoding human beta-cardiac myosin heavy chain (beta-MyHC). Force generation by myosins requires a tight and highly conserved allosteric coupling between its different protein domains. Hence, the effects of single point mutations on the force generation and kinetics of beta-cardiac myosin molecules cannot be predicted directly from their location within the protein structure. Great insight would be gained from understanding the link between the functional defect in the myosin protein and the clinical phenotypes of patients expressing them. Over the last decade, several single molecule techniques have been developed to understand in detail the chemomechanical cycle of different myosins. In this review, we highlight the single molecule techniques that can be used to assess the effect of point mutations on beta-cardiac myosin function. Recent bioengineering advances have enabled the micromanipulation of single cardiomyocyte cells to characterize their force-length dynamics. Here, we briefly review single cell micromanipulation as an approach to determine the effect of beta-MyHC mutations on cardiomyocyte function. Finally, we examine the technical challenges specific to studying beta-cardiac myosin function both using single molecule and single cell approaches.
Collapse
|
44
|
Carrier L, Schlossarek S, Willis MS, Eschenhagen T. The ubiquitin-proteasome system and nonsense-mediated mRNA decay in hypertrophic cardiomyopathy. Cardiovasc Res 2009; 85:330-8. [PMID: 19617224 DOI: 10.1093/cvr/cvp247] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Cardiomyopathies represent an important cause of cardiovascular morbidity and mortality due to heart failure, arrhythmias, and sudden death. Most forms of hypertrophic cardiomyopathy (HCM) are familial with an autosomal-dominant mode of inheritance. Over the last 20 years, the genetic basis of the disease has been largely unravelled. HCM is considered as a sarcomeropathy involving mutations in sarcomeric proteins, most often beta-myosin heavy chain and cardiac myosin-binding protein C. 'Missense' mutations, more common in the former, are associated with dysfunctional proteins stably integrated into the sarcomere. 'Nonsense' and frameshift mutations, more common in the latter, are associated with low mRNA and protein levels derived from the diseased allele, leading to haploinsufficiency of the remaining healthy allele. The two quality control systems responsible for the removal of the affected mRNAs and proteins are the nonsense-mediated mRNA decay (NMD) and the ubiquitin-proteasome system (UPS), respectively. This review discusses clinical and genetic aspects of HCM and the role of NMD and UPS in the regulation of mutant proteins, evidence for impairment of UPS as a pathogenic factor, as well as potential therapies for HCM.
Collapse
Affiliation(s)
- Lucie Carrier
- Institute of Experimental and Clinical Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, D-20246 Hamburg, Germany.
| | | | | | | |
Collapse
|
45
|
Carasso S, Rakowski H. Myocardial fibrosis and regional function in hypertrophic cardiomyopathy: may the force be with you. J Am Soc Echocardiogr 2009; 21:1306-8. [PMID: 19041573 DOI: 10.1016/j.echo.2008.10.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/04/2008] [Indexed: 11/16/2022]
Affiliation(s)
- Shemy Carasso
- Department of Cardiology, Rambam Health Care Campus, Haifa, Israel
| | | |
Collapse
|
46
|
Davis J, Westfall MV, Townsend D, Blankinship M, Herron TJ, Guerrero-Serna G, Wang W, Devaney E, Metzger JM. Designing heart performance by gene transfer. Physiol Rev 2008; 88:1567-651. [PMID: 18923190 DOI: 10.1152/physrev.00039.2007] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The birth of molecular cardiology can be traced to the development and implementation of high-fidelity genetic approaches for manipulating the heart. Recombinant viral vector-based technology offers a highly effective approach to genetically engineer cardiac muscle in vitro and in vivo. This review highlights discoveries made in cardiac muscle physiology through the use of targeted viral-mediated genetic modification. Here the history of cardiac gene transfer technology and the strengths and limitations of viral and nonviral vectors for gene delivery are reviewed. A comprehensive account is given of the application of gene transfer technology for studying key cardiac muscle targets including Ca(2+) handling, the sarcomere, the cytoskeleton, and signaling molecules and their posttranslational modifications. The primary objective of this review is to provide a thorough analysis of gene transfer studies for understanding cardiac physiology in health and disease. By comparing results obtained from gene transfer with those obtained from transgenesis and biophysical and biochemical methodologies, this review provides a global view of cardiac structure-function with an eye towards future areas of research. The data presented here serve as a basis for discovery of new therapeutic targets for remediation of acquired and inherited cardiac diseases.
Collapse
Affiliation(s)
- Jennifer Davis
- Department of Integrative Biology and Physiology, University of Minnesota Medical School, Minneapolis, Minnesota 55455, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
47
|
Herron TJ, Devaney EJ, Metzger JM. Modulation of cardiac performance by motor protein gene transfer. Ann N Y Acad Sci 2008; 1123:96-104. [PMID: 18375581 DOI: 10.1196/annals.1420.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Cardiac muscle performance can be determined by factors intrinsic to each cardiac muscle cell, such as protein isoform expression. One protein whose expression plays a major role in determining cardiac performance is myosin. Myosin is the heart's molecular motor which transduces the chemical energy from ATP hydrolysis into the mechanical energy of each heartbeat. Alterations of myosin isoform expression are routinely associated with acquired and inherited cases of cardiomyopathy. For example, human heart failure is consistently associated with increased expression of a slow myosin motor isoform and a concomitant decreased expression of the heart's fast myosin motor isoform. Further, mutations of the cardiac myosin gene are the most common cause of inherited hypertrophic cardiomyopathy. Transgenic animal studies have provided insight into cardiac functional effects caused by myosin isoform gene switching (fast-to-slow myosin or slow-to-fast myosin) or by expression of a disease-related mutant motor. More direct structure-function analysis using acute gene transfer of myosin motors provides evidence that the inotropic state of cardiac muscle can be affected by motor protein isoform shifting independent of intracellular calcium handling. Because most therapies for the diseased heart target intracellular calcium handling, acute gene transfer of cardiac molecular motors to modulate heart performance offers a novel therapeutic strategy for the compromised heart. Although the development of safe vectors for therapeutic myosin gene delivery are in their infancy, studies focused on acute genetic engineering of the heart's molecular motor will provide a foundation for therapeutic vector development and insight into mechanisms that contribute to cardiomyopathy.
Collapse
Affiliation(s)
- Todd J Herron
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI 48109, USA
| | | | | |
Collapse
|
48
|
Thick and thin filament gene mutations in striated muscle diseases. Int J Mol Sci 2008; 9:1259-1275. [PMID: 19325803 PMCID: PMC2635722 DOI: 10.3390/ijms9071259] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2008] [Revised: 05/23/2008] [Accepted: 06/12/2008] [Indexed: 01/05/2023] Open
Abstract
The sarcomere is the fundamental unit of cardiac and skeletal muscle contraction. During the last ten years, there has been growing awareness of the etiology of skeletal and cardiac muscle diseases originating in the sarcomere, an important evolving field. Many sarcomeric diseases affect newborn children, i. e. are congenital myopathies. The discovery and characterization of several myopathies caused by mutations in myosin heavy chain genes, coding for the major component of skeletal muscle thick filaments, has led to the introduction of a new entity in the field of neuromuscular disorders: myosin myopathies. Recently, mutations in genes coding for skeletal muscle thin filaments, associated with various clinical features, have been identified. These mutations evoke distinct structural changes within the sarcomeric thin filament. Current knowledge regarding contractile protein dysfunction as it relates to disease pathogenesis has failed to decipher the mechanistic links between mutations identified in sarcomeric proteins and skeletal myopathies, which will no doubt require an integrated physiological approach. The discovery of additional genes associated with myopathies and the elucidation of the molecular mechanisms of pathogenesis will lead to improved and more accurate diagnosis, including prenatally, and to enhanced potential for prognosis, genetic counseling and developing possible treatments for these diseases. The goal of this review is to present recent progress in the identification of gene mutations from each of the major structural components of the sarcomere, the thick and thin filaments, related to skeletal muscle disease. The genetics and clinical manifestations of these disorders will be discussed.
Collapse
|
49
|
Carasso S, Yang H, Woo A, Vannan MA, Jamorski M, Wigle ED, Rakowski H. Systolic Myocardial Mechanics in Hypertrophic Cardiomyopathy: Novel Concepts and Implications for Clinical Status. J Am Soc Echocardiogr 2008; 21:675-83. [DOI: 10.1016/j.echo.2007.10.021] [Citation(s) in RCA: 143] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/23/2007] [Indexed: 10/22/2022]
|
50
|
Lowey S, Lesko LM, Rovner AS, Hodges AR, White SL, Low RB, Rincon M, Gulick J, Robbins J. Functional effects of the hypertrophic cardiomyopathy R403Q mutation are different in an alpha- or beta-myosin heavy chain backbone. J Biol Chem 2008; 283:20579-89. [PMID: 18480046 DOI: 10.1074/jbc.m800554200] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The R403Q mutation in the beta-myosin heavy chain (MHC) was the first mutation to be linked to familial hypertrophic cardiomyopathy (FHC), a primary disease of heart muscle. The initial studies with R403Q myosin, isolated from biopsies of patients, showed a large decrease in myosin motor function, leading to the hypothesis that hypertrophy was a compensatory response. The introduction of the mouse model for FHC (the mouse expresses predominantly alpha-MHC as opposed to the beta-isoform in larger mammals) created a new paradigm for FHC based on finding enhanced motor function for R403Q alpha-MHC. To help resolve these conflicting mechanisms, we used a transgenic mouse model in which the endogenous alpha-MHC was largely replaced with transgenically encoded beta-MHC. A His(6) tag was cloned at the N terminus of the alpha-and beta-MHC to facilitate protein isolation by Ni(2+)-chelating chromatography. Characterization of the R403Q alpha-MHC by the in vitro motility assay showed a 30-40% increase in actin filament velocity compared with wild type, consistent with published studies. In contrast, the R403Q mutation in a beta-MHC backbone showed no enhancement in velocity. Cleavage of the His-tagged myosin by chymotrypsin made it possible to isolate homogeneous myosin subfragment 1 (S1), uncontaminated by endogenous myosin. We find that the actin-activated MgATPase activity for R403Q alpha-S1 is approximately 30% higher than for wild type, whereas the enzymatic activity for R403Q beta-S1 is reduced by approximately 10%. Thus, the functional consequences of the mutation are fundamentally changed depending upon the context of the cardiac MHC isoform.
Collapse
Affiliation(s)
- Susan Lowey
- Department of Molecular Physiology and Biophysics, University of Vermont, Burlington, VT 05405, USA.
| | | | | | | | | | | | | | | | | |
Collapse
|