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Friedman CE, Fayer S, Pendyala S, Chien WM, Loiben A, Tran L, Chao LS, McKinstry A, Ahmed D, Farris SD, Stempien-Otero A, Jonlin EC, Murry CE, Starita LM, Fowler DM, Yang KC. Multiplexed Functional Assessments of MYH7 Variants in Human Cardiomyocytes. CIRCULATION. GENOMIC AND PRECISION MEDICINE 2024; 17:e004377. [PMID: 38362799 PMCID: PMC11196868 DOI: 10.1161/circgen.123.004377] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2023] [Accepted: 01/08/2024] [Indexed: 02/17/2024]
Abstract
BACKGROUND Pathogenic autosomal-dominant missense variants in MYH7 (myosin heavy chain 7), which encodes the sarcomeric protein (β-MHC [beta myosin heavy chain]) expressed in cardiac and skeletal myocytes, are a leading cause of hypertrophic cardiomyopathy and are clinically actionable. However, ≈75% of MYH7 missense variants are of unknown significance. While human-induced pluripotent stem cells (hiPSCs) can be differentiated into cardiomyocytes to enable the interrogation of MYH7 variant effect in a disease-relevant context, deep mutational scanning has not been executed using diploid hiPSC derivates due to low hiPSC gene-editing efficiency. Moreover, multiplexable phenotypes enabling deep mutational scanning of MYH7 variant hiPSC-derived cardiomyocytes are unknown. METHODS To overcome these obstacles, we used CRISPRa On-Target Editing Retrieval enrichment to generate an hiPSC library containing 113 MYH7 codon variants suitable for deep mutational scanning. We first established that β-MHC protein loss occurs in a hypertrophic cardiomyopathy human heart with a pathogenic MYH7 variant. We then differentiated the MYH7 missense variant hiPSC library to cardiomyocytes for multiplexed assessment of β-MHC variant abundance by massively parallel sequencing and hiPSC-derived cardiomyocyte survival. RESULTS Both the multiplexed assessment of β-MHC abundance and hiPSC-derived cardiomyocyte survival accurately segregated all known pathogenic variants from synonymous variants. Functional data were generated for 4 variants of unknown significance and 58 additional MYH7 missense variants not yet detected in patients. CONCLUSIONS This study leveraged hiPSC differentiation into disease-relevant cardiomyocytes to enable multiplexed assessments of MYH7 missense variants for the first time. Phenotyping strategies used here enable the application of deep mutational scanning to clinically actionable genes, which should reduce the burden of variants of unknown significance on patients and clinicians.
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Affiliation(s)
- Clayton E. Friedman
- Institute for Stem Cell & Regenerative Medicine, Univ of Washington, School of Medicine; Seattle, WA
- Center for Cardiovascular Biology, Univ of Washington; Seattle, WA
- Dept of Medicine/Cardiology, Univ of Washington; Seattle, WA
| | - Shawn Fayer
- Dept of Genome Sciences, Univ of Washington; Seattle, WA
| | | | - Wei-Ming Chien
- Institute for Stem Cell & Regenerative Medicine, Univ of Washington, School of Medicine; Seattle, WA
- Center for Cardiovascular Biology, Univ of Washington; Seattle, WA
- Dept of Medicine/Cardiology, Univ of Washington; Seattle, WA
- Cardiology/Hospital Specialty Medicine, VA Puget Sound HCS; Seattle, WA
| | - Alexander Loiben
- Institute for Stem Cell & Regenerative Medicine, Univ of Washington, School of Medicine; Seattle, WA
- Center for Cardiovascular Biology, Univ of Washington; Seattle, WA
- Dept of Medicine/Cardiology, Univ of Washington; Seattle, WA
| | - Linda Tran
- Institute for Stem Cell & Regenerative Medicine, Univ of Washington, School of Medicine; Seattle, WA
- Center for Cardiovascular Biology, Univ of Washington; Seattle, WA
- Dept of Medicine/Cardiology, Univ of Washington; Seattle, WA
| | - Leslie S. Chao
- Institute for Stem Cell & Regenerative Medicine, Univ of Washington, School of Medicine; Seattle, WA
- Center for Cardiovascular Biology, Univ of Washington; Seattle, WA
- Dept of Medicine/Cardiology, Univ of Washington; Seattle, WA
| | - Ashley McKinstry
- Institute for Stem Cell & Regenerative Medicine, Univ of Washington, School of Medicine; Seattle, WA
- Center for Cardiovascular Biology, Univ of Washington; Seattle, WA
- Dept of Medicine/Cardiology, Univ of Washington; Seattle, WA
| | - Dania Ahmed
- Institute for Stem Cell & Regenerative Medicine, Univ of Washington, School of Medicine; Seattle, WA
- Center for Cardiovascular Biology, Univ of Washington; Seattle, WA
- Dept of Medicine/Cardiology, Univ of Washington; Seattle, WA
| | - Stephen D. Farris
- Dept of Medicine/Cardiology, Univ of Washington; Seattle, WA
- Cardiology/Hospital Specialty Medicine, VA Puget Sound HCS; Seattle, WA
| | - April Stempien-Otero
- Center for Cardiovascular Biology, Univ of Washington; Seattle, WA
- Dept of Medicine/Cardiology, Univ of Washington; Seattle, WA
| | - Erica C. Jonlin
- Institute for Stem Cell & Regenerative Medicine, Univ of Washington, School of Medicine; Seattle, WA
| | - Charles E. Murry
- Institute for Stem Cell & Regenerative Medicine, Univ of Washington, School of Medicine; Seattle, WA
- Center for Cardiovascular Biology, Univ of Washington; Seattle, WA
- Dept of Medicine/Cardiology, Univ of Washington; Seattle, WA
- Dept of Laboratory Medicine & Pathology, Univ of Washington; Seattle, WA
- Dept of Bioengineering, Univ of Washington; Seattle, WA
| | - Lea M. Starita
- Dept of Genome Sciences, Univ of Washington; Seattle, WA
- Brotman Baty Institute for Precision Medicine, Seattle, WA
| | - Douglas M. Fowler
- Dept of Genome Sciences, Univ of Washington; Seattle, WA
- Dept of Bioengineering, Univ of Washington; Seattle, WA
- Brotman Baty Institute for Precision Medicine, Seattle, WA
| | - Kai-Chun Yang
- Institute for Stem Cell & Regenerative Medicine, Univ of Washington, School of Medicine; Seattle, WA
- Center for Cardiovascular Biology, Univ of Washington; Seattle, WA
- Dept of Medicine/Cardiology, Univ of Washington; Seattle, WA
- Cardiology/Hospital Specialty Medicine, VA Puget Sound HCS; Seattle, WA
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Naderi N, Mohsen-Pour N, Nilipour Y, Pourirahim M, Maleki M, Kalayinia S. A novel heterozygous missense MYH7 mutation potentially causes an autosomal dominant form of myosin storage myopathy with dilated cardiomyopathy. BMC Cardiovasc Disord 2023; 23:487. [PMID: 37794383 PMCID: PMC10552240 DOI: 10.1186/s12872-023-03538-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2023] [Accepted: 09/27/2023] [Indexed: 10/06/2023] Open
Abstract
BACKGROUND The MYH7 gene, which encodes the slow/ß-cardiac myosin heavy chain, is mutated in myosin storage myopathy (MSM). The clinical spectrum of MSM is quite heterogeneous in that it ranges from cardiomyopathies to skeletal myopathies or a combination of both, depending on the affected region. In this study, we performed clinical and molecular examinations of the proband of an Iranian family with MSM in an autosomal dominant condition exhibiting proximal muscle weakness and dilated cardiomyopathy. METHODS Following thorough clinical and paraclinical examinations, whole-exome sequencing `was performed on the proband (II-5). Pathogenicity prediction of the candidate variant was performed through in-silico analysis. Co-segregation analysis of the WES data among the family members was carried out by PCR-based Sanger sequencing. RESULTS A novel heterozygous missense variant, MYH7 (NM_000257): c.C1888A: p.Pro630Thr, was found in the DNA of the proband and his children and confirmed by Sanger sequencing. The in-silico analysis revealed that p.Pro630Thr substitution was deleterious. The novel sequence variant fell within a highly conserved region of the head domain. Our findings expand the spectrum of MYH7 mutations. CONCLUSIONS This finding could improve genetic counseling and prenatal diagnosis in families with clinical manifestations associated with MYH7-related myopathy.
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Affiliation(s)
- Niloofar Naderi
- Cardiogenetic Research Center, Rajaie Cardiovascular Medical and Research Center, University of Medical Sciences, Tehran, Iran
| | - Neda Mohsen-Pour
- Zanjan Pharmaceutical Biotechnology Research Center, Zanjan University of Medical Sciences, Zanjan, Iran
| | - Yalda Nilipour
- Pediatric pathology research center, Research institute for children's health, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Maryam Pourirahim
- Cardiogenetic Research Center, Rajaie Cardiovascular Medical and Research Center, University of Medical Sciences, Tehran, Iran
| | - Majid Maleki
- Cardiogenetic Research Center, Rajaie Cardiovascular Medical and Research Center, University of Medical Sciences, Tehran, Iran
| | - Samira Kalayinia
- Cardiogenetic Research Center, Rajaie Cardiovascular Medical and Research Center, University of Medical Sciences, Tehran, Iran.
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3
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Osten J, Mohebbi M, Uta P, Matinmehr F, Wang T, Kraft T, Amrute-Nayak M, Scholz T. Myosin essential light chain 1sa decelerates actin and thin filament gliding on β-myosin molecules. J Gen Physiol 2022; 154:213440. [PMID: 36053243 PMCID: PMC9441736 DOI: 10.1085/jgp.202213149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2022] [Accepted: 08/05/2022] [Indexed: 11/20/2022] Open
Abstract
The β-myosin heavy chain expressed in ventricular myocardium and the myosin heavy chain (MyHC) in slow-twitch skeletal Musculus soleus (M. soleus) type-I fibers are both encoded by MYH7. Thus, these myosin molecules are deemed equivalent. However, some reports suggested variations in the light chain composition between M. soleus and ventricular myosin, which could influence functional parameters, such as maximum velocity of shortening. To test for functional differences of the actin gliding velocity on immobilized myosin molecules, we made use of in vitro motility assays. We found that ventricular myosin moved actin filaments with ∼0.9 µm/s significantly faster than M. soleus myosin (0.3 µm/s). Filaments prepared from isolated actin are not the native interaction partner of myosin and are believed to slow down movement. Yet, using native thin filaments purified from M. soleus or ventricular tissue, the gliding velocity of M. soleus and ventricular myosin remained significantly different. When comparing the light chain composition of ventricular and M. soleus β-myosin, a difference became evident. M. soleus myosin contains not only the "ventricular" essential light chain (ELC) MLC1sb/v, but also an additional longer and more positively charged MLC1sa. Moreover, we revealed that on a single muscle fiber level, a higher relative content of MLC1sa was associated with significantly slower actin gliding. We conclude that the ELC MLC1sa decelerates gliding velocity presumably by a decreased dissociation rate from actin associated with a higher actin affinity compared to MLC1sb/v. Such ELC/actin interactions might also be relevant in vivo as differences between M. soleus and ventricular myosin persisted when native thin filaments were used.
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Affiliation(s)
- Jennifer Osten
- Molecular and Cellular Physiology, Hannover Medical School, Hannover, Germany
| | - Maral Mohebbi
- Molecular and Cellular Physiology, Hannover Medical School, Hannover, Germany
| | - Petra Uta
- Molecular and Cellular Physiology, Hannover Medical School, Hannover, Germany
| | - Faramarz Matinmehr
- Molecular and Cellular Physiology, Hannover Medical School, Hannover, Germany
| | - Tianbang Wang
- Molecular and Cellular Physiology, Hannover Medical School, Hannover, Germany
| | - Theresia Kraft
- Molecular and Cellular Physiology, Hannover Medical School, Hannover, Germany
| | - Mamta Amrute-Nayak
- Molecular and Cellular Physiology, Hannover Medical School, Hannover, Germany
| | - Tim Scholz
- Molecular and Cellular Physiology, Hannover Medical School, Hannover, Germany,Correspondence to Tim Scholz:
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4
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Devina T, Wong YH, Hsiao CW, Li YJ, Lien CC, Cheng IHJ. Endoplasmic reticulum stress induces Alzheimer's disease-like phenotypes in the neuron derived from the induced pluripotent stem cell with D678H mutation on amyloid precursor protein. J Neurochem 2022; 163:26-39. [PMID: 35943292 DOI: 10.1111/jnc.15687] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2021] [Revised: 07/12/2022] [Accepted: 08/06/2022] [Indexed: 11/28/2022]
Abstract
Alzheimer's disease (AD), a progressive neurodegenerative disorder, is mainly caused by the interaction of genetic and environmental factors. The impact of environmental factors on the genetic mutation in the amyloid precursor protein (APP) is not well characterized. We hypothesized that Endoplasmic Reticulum (ER) stress would promote disease for the patient carrying the APP D678H mutation. Therefore, we analyzed the impact of a familial AD mutation on amyloid precursor protein (APP D678H) under ER stress. Induced pluripotent stem cell (iPSC) from APP D678H mutant carrier was differentiated into neurons, which were then analyzed for AD-like changes. Immunocytochemistry and whole-cell patch-clamp recording revealed that the derived neurons on day 28 after differentiation showed neuronal markers and electrophysiological properties similar to those of mature neurons. However, the APP D678H mutant neurons did not have significant alterations in the levels of amyloid-β (Aβ) and phosphorylated tau (pTau) compared to its isogenic wild-type neuron. Only under ER stress, the neurons with the APP D678H mutation had more Aβ and pTau via immune detection assays. The higher level of Aβ in the APP D678H mutant neurons was probably due to the increased level of β-site APP cleaving enzyme (BACE1) and decreased level of Aβ degrading enzymes under ER stress. Increased Aβ and pTau under ER stress reduced the N-methyl-D-aspartate receptor (NMDAR) in Western blot analysis and altered electrophysiological properties in the mutant neurons. Our study provides evidence that the interaction between genetic mutation and ER stress would induce AD-like changes.
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Affiliation(s)
- Tania Devina
- Taiwan International Graduate Program in Molecular Medicine, National Yang Ming Chiao Tung University and Academia Sinica, Taipei, Taiwan.,Institute of Brain Science, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Yu-Hui Wong
- Brain Research Center, National Yang Ming Chiao Tung University, Taipei, Taiwan.,Department of Life Science and Institute of Genome Science, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Chiao-Wan Hsiao
- Institute of Brain Science, National Yang Ming Chiao Tung University, Taipei, Taiwan.,Program in Molecular Medicine, National Yang Ming Chiao Tung University and Academia Sinica, Taipei, Taiwan
| | - Yu-Jui Li
- Institute of Neuroscience, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Cheng-Chang Lien
- Taiwan International Graduate Program in Molecular Medicine, National Yang Ming Chiao Tung University and Academia Sinica, Taipei, Taiwan.,Brain Research Center, National Yang Ming Chiao Tung University, Taipei, Taiwan.,Program in Molecular Medicine, National Yang Ming Chiao Tung University and Academia Sinica, Taipei, Taiwan.,Institute of Neuroscience, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Irene Han-Juo Cheng
- Taiwan International Graduate Program in Molecular Medicine, National Yang Ming Chiao Tung University and Academia Sinica, Taipei, Taiwan.,Brain Research Center, National Yang Ming Chiao Tung University, Taipei, Taiwan.,Institute of Brain Science, National Yang Ming Chiao Tung University, Taipei, Taiwan.,Program in Molecular Medicine, National Yang Ming Chiao Tung University and Academia Sinica, Taipei, Taiwan
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5
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Becker E, Francino A, Pich A, Perrot A, Kraft T, Radocaj A. AQUA Mutant Protein Quantification of Endomyocardial Biopsy-Sized Samples From a Patient With Hypertrophic Cardiomyopathy. Front Cardiovasc Med 2022; 9:816330. [PMID: 35265683 PMCID: PMC8899185 DOI: 10.3389/fcvm.2022.816330] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Accepted: 01/28/2022] [Indexed: 11/13/2022] Open
Abstract
In genetic diseases like hypertrophic cardiomyopathy, reliable quantification of the expression level of mutant protein can play an important role in disease research, diagnosis, treatment and prognosis. For heterozygous β-myosin heavy chain (β-MyHC) mutations it has been shown that disease severity is related to the fraction of mutant protein in the myocardium. Yet, heart tissue from patients with genetically characterized diseases is scarce. Here we asked, if even in the case of small endomyocardial biopsies, single quantifications produce reliable results. Myocardial samples were taken from four different regions of an explanted heart of a patient with hypertrophic cardiomyopathy carrying point mutation p.Gly716Arg in β-MyHC. From both, large samples (15 mg) and small, endomyocardial biopsy-sized samples (≤ 1 mg) myosin was extracted and enzymatically digested to yield a specific peptide of interest that allowed to distinguish mutant and wild-type β-MyHC. Absolute quantification by mass spectrometry (AQUA) of the peptide of interest was performed repeatedly for both sample sizes to determine the fraction of mutant β-MyHC. Fractions of mutant β-MyHC (32% on average) showed only small differences between the four cardiac regions and for large and small samples. The standard deviations were smaller than five percentage points for all cardiac regions. The two quantification methods (large and small sample size) produce results with comparable accuracy and precision. Consequently, with our method even small endomyocardial biopsies allow reliable protein quantification for potential diagnostic purposes.
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Affiliation(s)
- Edgar Becker
- Institute for Molecular and Cell Physiology, Hannover Medical School, Hannover, Germany
| | - Antonio Francino
- Cardiology Department, Hospital Clinic/IDIBAPS, University of Barcelona, Barcelona, Spain
| | - Andreas Pich
- Institute of Toxicology, Hannover Medical School, Hannover, Germany
| | - Andreas Perrot
- Experimental and Clinical Research Center, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Theresia Kraft
- Institute for Molecular and Cell Physiology, Hannover Medical School, Hannover, Germany
| | - Ante Radocaj
- Institute for Molecular and Cell Physiology, Hannover Medical School, Hannover, Germany
- *Correspondence: Ante Radocaj
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6
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Ušaj M, Moretto L, Månsson A. Critical Evaluation of Current Hypotheses for the Pathogenesis of Hypertrophic Cardiomyopathy. Int J Mol Sci 2022; 23:2195. [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] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Revised: 02/07/2022] [Accepted: 02/14/2022] [Indexed: 02/04/2023] Open
Abstract
Hereditary hypertrophic cardiomyopathy (HCM), due to mutations in sarcomere proteins, occurs in more than 1/500 individuals and is the leading cause of sudden cardiac death in young people. The clinical course exhibits appreciable variability. However, typically, heart morphology and function are normal at birth, with pathological remodeling developing over years to decades, leading to a phenotype characterized by asymmetric ventricular hypertrophy, scattered fibrosis and myofibrillar/cellular disarray with ultimate mechanical heart failure and/or severe arrhythmias. The identity of the primary mutation-induced changes in sarcomere function and how they trigger debilitating remodeling are poorly understood. Support for the importance of mutation-induced hypercontractility, e.g., increased calcium sensitivity and/or increased power output, has been strengthened in recent years. However, other ideas that mutation-induced hypocontractility or non-uniformities with contractile instabilities, instead, constitute primary triggers cannot yet be discarded. Here, we review evidence for and criticism against the mentioned hypotheses. In this process, we find support for previous ideas that inefficient energy usage and a blunted Frank-Starling mechanism have central roles in pathogenesis, although presumably representing effects secondary to the primary mutation-induced changes. While first trying to reconcile apparently diverging evidence for the different hypotheses in one unified model, we also identify key remaining questions and suggest how experimental systems that are built around isolated primarily expressed proteins could be useful.
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Affiliation(s)
| | | | - Alf Månsson
- Department of Chemistry and Biomedical Sciences, Faculty of Health and Life Sciences, Linnaeus University, SE-39182 Kalmar, Sweden; (M.U.); (L.M.)
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7
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Kraft T, Montag J. Altered force generation and cell-to-cell contractile imbalance in hypertrophic cardiomyopathy. Pflugers Arch 2019; 471:719-733. [PMID: 30740621 PMCID: PMC6475633 DOI: 10.1007/s00424-019-02260-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Accepted: 01/20/2019] [Indexed: 01/18/2023]
Abstract
Hypertrophic cardiomyopathy (HCM) is mainly caused by mutations in sarcomeric proteins. Thirty to forty percent of identified mutations are found in the ventricular myosin heavy chain (β-MyHC). A common mechanism explaining how numerous mutations in several different proteins induce a similar HCM-phenotype is unclear. It was proposed that HCM-mutations cause hypercontractility, which for some mutations is thought to result from mutation-induced unlocking of myosin heads from a so-called super-relaxed state (SRX). The SRX was suggested to be related to the "interacting head motif," i.e., pairs of myosin heads folded back onto their S2-region. Here, we address these structural states of myosin in context of earlier work on weak binding cross-bridges. However, not all HCM-mutations cause hypercontractility and/or are involved in the interacting head motif. But most likely, all mutations alter the force generating mechanism, yet in different ways, possibly including inhibition of SRX. Such functional-hyper- and hypocontractile-changes are the basis of our previously proposed concept stating that contractile imbalance due to unequal fractions of mutated and wildtype protein among individual cardiomyocytes over time will induce cardiomyocyte disarray and fibrosis, hallmarks of HCM. Studying β-MyHC-mutations, we found substantial contractile variability from cardiomyocyte to cardiomyocyte within a patient's myocardium, much higher than in controls. This was paralleled by a similarly variable fraction of mutant MYH7-mRNA (cell-to-cell allelic imbalance), due to random, burst-like transcription, independent for mutant and wildtype MYH7-alleles. Evidence suggests that HCM-mutations in other sarcomeric proteins follow the same disease mechanism.
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Affiliation(s)
- Theresia Kraft
- Molecular and Cell Physiology, Hannover Medical School, Carl-Neuberg-Str. 1, 30625, Hannover, Germany
| | - Judith Montag
- Molecular and Cell Physiology, Hannover Medical School, Carl-Neuberg-Str. 1, 30625, Hannover, Germany.
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8
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The Molecular Mechanisms of Mutations in Actin and Myosin that Cause Inherited Myopathy. Int J Mol Sci 2018; 19:ijms19072020. [PMID: 29997361 PMCID: PMC6073311 DOI: 10.3390/ijms19072020] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2018] [Revised: 07/06/2018] [Accepted: 07/08/2018] [Indexed: 12/23/2022] Open
Abstract
The discovery that mutations in myosin and actin genes, together with mutations in the other components of the muscle sarcomere, are responsible for a range of inherited muscle diseases (myopathies) has revolutionized the study of muscle, converting it from a subject of basic science to a relevant subject for clinical study and has been responsible for a great increase of interest in muscle studies. Myopathies are linked to mutations in five of the myosin heavy chain genes, three of the myosin light chain genes, and three of the actin genes. This review aims to determine to what extent we can explain disease phenotype from the mutant genotype. To optimise our chances of finding the right mechanism we must study a myopathy where there are a large number of different mutations that cause a common phenotype and so are likely to have a common mechanism: a corollary to this criterion is that if any mutation causes the disease phenotype but does not correspond to the proposed mechanism, then the whole mechanism is suspect. Using these criteria, we consider two cases where plausible genotype-phenotype mechanisms have been proposed: the actin “A-triad” and the myosin “mesa/IHD” models.
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9
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Montag J, Syring M, Rose J, Weber AL, Ernstberger P, Mayer AK, Becker E, Keyser B, Dos Remedios C, Perrot A, van der Velden J, Francino A, Navarro-Lopez F, Ho CY, Brenner B, Kraft T. Intrinsic MYH7 expression regulation contributes to tissue level allelic imbalance in hypertrophic cardiomyopathy. J Muscle Res Cell Motil 2017; 38:291-302. [PMID: 29101517 PMCID: PMC5742120 DOI: 10.1007/s10974-017-9486-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Accepted: 10/28/2017] [Indexed: 11/29/2022]
Abstract
HCM, the most common inherited cardiac disease, is mainly caused by mutations in sarcomeric genes. More than a third of the patients are heterozygous for mutations in the MYH7 gene encoding for the β-myosin heavy chain. In HCM-patients, expression of the mutant and the wildtype allele can be unequal, thus leading to fractions of mutant and wildtype mRNA and protein which deviate from 1:1. This so-called allelic imbalance was detected in whole tissue samples but also in individual cells. There is evidence that the severity of HCM not only depends on the functional effect of the mutation itself, but also on the fraction of mutant protein in the myocardial tissue. Allelic imbalance has been shown to occur in a broad range of genes. Therefore, we aimed to examine whether the MYH7-alleles are intrinsically expressed imbalanced or whether the allelic imbalance is solely associated with the disease. We compared the expression of MYH7-alleles in non-HCM donors and in HCM-patients with different MYH7-missense mutations. In the HCM-patients, we identified imbalanced as well as equal expression of both alleles. Also at the protein level, allelic imbalance was determined. Most interestingly, we also discovered allelic imbalance and balance in non-HCM donors. Our findings therefore strongly indicate that apart from mutation-specific mechanisms, also non-HCM associated allelic-mRNA expression regulation may account for the allelic imbalance of the MYH7 gene in HCM-patients. Since the relative amount of mutant mRNA and protein or the extent of allelic imbalance has been associated with the severity of HCM, individual analysis of the MYH7-allelic expression may provide valuable information for the prognosis of each patient.
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Affiliation(s)
- Judith Montag
- Institute of Molecular and Cell Physiology, Hannover Medical School, Hanover, Germany.
| | - Mandy Syring
- Institute of Molecular and Cell Physiology, Hannover Medical School, Hanover, Germany
| | - Julia Rose
- Institute of Molecular and Cell Physiology, Hannover Medical School, Hanover, Germany
| | - Anna-Lena Weber
- Institute of Molecular and Cell Physiology, Hannover Medical School, Hanover, Germany
| | - Pia Ernstberger
- Institute of Molecular and Cell Physiology, Hannover Medical School, Hanover, Germany
| | - Anne-Kathrin Mayer
- Institute of Molecular and Cell Physiology, Hannover Medical School, Hanover, Germany
| | - Edgar Becker
- Institute of Molecular and Cell Physiology, Hannover Medical School, Hanover, Germany
| | - Britta Keyser
- Institute of Human Genetics, Hannover Medical School, Hanover, Germany
| | | | - Andreas Perrot
- Experimental and Clinical Research Center, Charité-University Clinic Berlin, Berlin, Germany
| | - Jolanda van der Velden
- Department of Physiology, Institute for Cardiovascular Research, VU University, Amsterdam, The Netherlands
| | - Antonio Francino
- Hospital Clinic/IDIBAPS, University of Barcelona, Barcelona, Spain
| | | | | | - Bernhard Brenner
- Institute of Molecular and Cell Physiology, Hannover Medical School, Hanover, Germany
| | - Theresia Kraft
- Institute of Molecular and Cell Physiology, Hannover Medical School, Hanover, Germany
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10
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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.
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Affiliation(s)
- Melanie Colegrave
- Faculty of Biological Sciences, School of Molecular and Cellular Biology, University of Leeds, Leeds LS2 9JT, United Kingdom
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11
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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.
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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
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12
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Ljunggren S, Levels JHM, Turkina MV, Sundberg S, Bochem AE, Hovingh K, Holleboom AG, Lindahl M, Kuivenhoven JA, Karlsson H. ApoA-I mutations, L202P and K131del, in HDL from heterozygotes with low HDL-C. Proteomics Clin Appl 2014; 8:241-50. [DOI: 10.1002/prca.201300014] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2013] [Revised: 09/04/2013] [Accepted: 10/04/2013] [Indexed: 12/11/2022]
Affiliation(s)
- Stefan Ljunggren
- Occupational and Environmental Medicine; Department of Clinical and Experimental Medicine; Linköping University; Linköping Sweden
| | | | - Maria V. Turkina
- Division of Cell Biology; Department of Clinical and Experimental Medicine; Linköping University; Linköping Sweden
| | - Sofie Sundberg
- Occupational and Environmental Medicine; Department of Clinical and Experimental Medicine; Linköping University; Linköping Sweden
| | - Andrea E. Bochem
- Department of Vascular Medicine; Academic Medical Centre; Amsterdam The Netherlands
| | - Kees Hovingh
- Department of Vascular Medicine; Academic Medical Centre; Amsterdam The Netherlands
| | - Adriaan G. Holleboom
- Department of Vascular Medicine; Academic Medical Centre; Amsterdam The Netherlands
| | - Mats Lindahl
- Occupational and Environmental Medicine; Department of Clinical and Experimental Medicine; Linköping University; Linköping Sweden
| | - Jan Albert Kuivenhoven
- Department of Molecular Genetics; University Medical Center Groningen; University of Groningen; Groningen The Netherlands
| | - Helen Karlsson
- Occupational and Environmental Medicine; Department of Clinical and Experimental Medicine; Linköping University; Linköping Sweden
- Department of Occupational and Environmental Medicine; Heart Medical Centre; Linköping Sweden
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13
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Clarke NF, Amburgey K, Teener J, Camelo-Piragua S, Kesari A, Punetha J, Waddell LB, Davis M, Laing NG, Monnier N, North KN, Hoffman EP, Dowling JJ. A novel mutation expands the genetic and clinical spectrum of MYH7-related myopathies. Neuromuscul Disord 2013; 23:432-6. [PMID: 23478172 DOI: 10.1016/j.nmd.2013.02.009] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2012] [Revised: 02/08/2013] [Accepted: 02/12/2013] [Indexed: 01/16/2023]
Abstract
MYH7 mutations are an established cause of Laing distal myopathy, myosin storage myopathy, and cardiomyopathy, as well as additional myopathy subtypes. We report a novel MYH7 mutation (p.Leu1597Arg) that arose de novo in two unrelated probands. Proband 1 has a myopathy characterized by distal weakness and prominent contractures and histopathology typical of multi-minicore disease. Proband 2 has an axial myopathy and histopathology consistent with congenital fiber type disproportion. These cases highlight the broad spectrum of clinical and histological patterns associated with MYH7 mutations, and provide further evidence that MYH7 is likely responsible for a greater proportion of congenital myopathies than currently appreciated.
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Affiliation(s)
- Nigel F Clarke
- INMR, The Children's Hospital at Westmead & Discipline of Paediatrics and Child Health, University of Sydney, Sydney, Australia
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14
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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.
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15
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Mechanical and kinetic properties of β-cardiac/slow skeletal muscle myosin. J Muscle Res Cell Motil 2012; 33:403-17. [DOI: 10.1007/s10974-012-9315-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2012] [Accepted: 07/06/2012] [Indexed: 11/26/2022]
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16
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Tripathi S, Schultz I, Becker E, Montag J, Borchert B, Francino A, Navarro-Lopez F, Perrot A, Özcelik C, Osterziel KJ, McKenna WJ, Brenner B, Kraft T. Unequal allelic expression of wild-type and mutated β-myosin in familial hypertrophic cardiomyopathy. Basic Res Cardiol 2011; 106:1041-55. [PMID: 21769673 PMCID: PMC3228959 DOI: 10.1007/s00395-011-0205-9] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/26/2011] [Revised: 06/29/2011] [Accepted: 07/07/2011] [Indexed: 11/29/2022]
Abstract
Familial hypertrophic cardiomyopathy (FHC) is an autosomal dominant disease, which in about 30% of the patients is caused by missense mutations in one allele of the β-myosin heavy chain (β-MHC) gene (MYH7). To address potential molecular mechanisms underlying the family-specific prognosis, we determined the relative expression of mutant versus wild-type MYH7-mRNA. We found a hitherto unknown mutation-dependent unequal expression of mutant to wild-type MYH7-mRNA, which is paralleled by similar unequal expression of β-MHC at the protein level. Relative abundance of mutated versus wild-type MYH7-mRNA was determined by a specific restriction digest approach and by real-time PCR (RT-qPCR). Fourteen samples from M. soleus and myocardium of 12 genotyped and clinically well-characterized FHC patients were analyzed. The fraction of mutated MYH7-mRNA in five patients with mutation R723G averaged to 66 and 68% of total MYH7-mRNA in soleus and myocardium, respectively. For mutations I736T, R719W and V606M, fractions of mutated MYH7-mRNA in M. soleus were 39, 57 and 29%, respectively. For all mutations, unequal abundance was similar at the protein level. Importantly, fractions of mutated transcripts were comparable among siblings, in younger relatives and unrelated carriers of the same mutation. Hence, the extent of unequal expression of mutated versus wild-type transcript and protein is characteristic for each mutation, implying cis-acting regulatory mechanisms. Bioinformatics suggest mRNA stability or splicing effectors to be affected by certain mutations. Intriguingly, we observed a correlation between disease expression and fraction of mutated mRNA and protein. This strongly suggests that mutation-specific allelic imbalance represents a new pathogenic factor for FHC.
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Affiliation(s)
- Snigdha Tripathi
- Institute of Molecular and Cell Physiology, Hannover Medical School, Carl Neuberg Str. 1, 30625 Hannover, Germany
| | - Imke Schultz
- Institute of Molecular and Cell Physiology, Hannover Medical School, Carl Neuberg Str. 1, 30625 Hannover, Germany
- Present Address: Niederwiesenring 4, 63110 Rodgau, Germany
| | - Edgar Becker
- Institute of Molecular and Cell Physiology, Hannover Medical School, Carl Neuberg Str. 1, 30625 Hannover, Germany
| | - Judith Montag
- Institute of Molecular and Cell Physiology, Hannover Medical School, Carl Neuberg Str. 1, 30625 Hannover, Germany
| | - Bianca Borchert
- Institute of Molecular and Cell Physiology, Hannover Medical School, Carl Neuberg Str. 1, 30625 Hannover, Germany
- Present Address: Department of Cardiac, Thoracic, Transplantation and Vascular Surgery, Hannover Medical School, Carl-Neuberg Str. 1, 30625 Hannover, Germany
| | - Antonio Francino
- Hospital Clinic/IDIBAPS, University of Barcelona, 08036 Barcelona, Spain
| | | | - Andreas Perrot
- Charité-Unversitätsmedizin Berlin, Experimental and Clinical Research Center (ECRC) am Max-Delbrück-Centrum für Molekulare Medizin, Kardio-Genetisches Labor, 13125 Berlin, Germany
| | - Cemil Özcelik
- Charité-Unversitätsmedizin Berlin, Experimental and Clinical Research Center (ECRC) am Max-Delbrück-Centrum für Molekulare Medizin, Kardio-Genetisches Labor, 13125 Berlin, Germany
- Charité-Universitätsmedizin Berlin, Kardiologie am Campus Virchow-Klinikum, 13353 Berlin, Germany
| | - Karl-Josef Osterziel
- Charité-Universitätsmedizin Berlin, Kardiologie am Campus Virchow-Klinikum, 13353 Berlin, Germany
- Present Address: Kardiologische Gemeinschaftspraxis, Marienstraße 9, 92224 Amberg, Germany
| | - William J. McKenna
- Institute of Cardiovascular Science, University College London, London, WC1E 6BT United Kingdom
| | - Bernhard Brenner
- Institute of Molecular and Cell Physiology, Hannover Medical School, Carl Neuberg Str. 1, 30625 Hannover, Germany
| | - Theresia Kraft
- Institute of Molecular and Cell Physiology, Hannover Medical School, Carl Neuberg Str. 1, 30625 Hannover, Germany
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17
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Song W, Dyer E, Stuckey DJ, Copeland O, Leung MC, Bayliss C, Messer A, Wilkinson R, Tremoleda JL, Schneider MD, Harding SE, Redwood CS, Clarke K, Nowak K, Monserrat L, Wells D, Marston SB. Molecular mechanism of the E99K mutation in cardiac actin (ACTC Gene) that causes apical hypertrophy in man and mouse. J Biol Chem 2011; 286:27582-93. [PMID: 21622575 PMCID: PMC3149350 DOI: 10.1074/jbc.m111.252320] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2011] [Revised: 05/18/2011] [Indexed: 11/06/2022] Open
Abstract
We generated a transgenic mouse model expressing the apical hypertrophic cardiomyopathy-causing mutation ACTC E99K at 50% of total heart actin and compared it with actin from patients carrying the same mutation. The actin mutation caused a higher Ca(2+) sensitivity in reconstituted thin filaments measured by in vitro motility assay (2.3-fold for mice and 1.3-fold for humans) and in skinned papillary muscle. The mutation also abolished the change in Ca(2+) sensitivity normally linked to troponin I phosphorylation. MyBP-C and troponin I phosphorylation levels were the same as controls in transgenic mice and human carrier heart samples. ACTC E99K mice exhibited a high death rate between 28 and 45 days (48% females and 22% males). At 21 weeks, the hearts of the male survivors had enlarged atria, increased interstitial fibrosis, and sarcomere disarray. MRI showed hypertrophy, predominantly at the apex of the heart. End-diastolic volume and end-diastolic pressure were increased, and relaxation rates were reduced compared with nontransgenic littermates. End-systolic pressures and volumes were unaltered. ECG abnormalities were present, and the contractile response to β-adrenergic stimulation was much reduced. Older mice (29-week-old females and 38-week-old males) developed dilated cardiomyopathy with increased end-systolic volume and continuing increased end-diastolic pressure and slower contraction and relaxation rates. ECG showed atrial flutter and frequent atrial ectopic beats at rest in some ACTC E99K mice. We propose that the ACTC E99K mutation causes higher myofibrillar Ca(2+) sensitivity that is responsible for the sudden cardiac death, apical hypertrophy, and subsequent development of heart failure in humans and mice.
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Affiliation(s)
- Weihua Song
- From the National Heart and Lung Institute, Imperial College London, London SW32 6LY, United Kingdom
| | - Emma Dyer
- From the National Heart and Lung Institute, Imperial College London, London SW32 6LY, United Kingdom
| | - Daniel J. Stuckey
- From the National Heart and Lung Institute, Imperial College London, London SW32 6LY, United Kingdom
| | - O'Neal Copeland
- From the National Heart and Lung Institute, Imperial College London, London SW32 6LY, United Kingdom
| | - Man-Ching Leung
- From the National Heart and Lung Institute, Imperial College London, London SW32 6LY, United Kingdom
| | - Christopher Bayliss
- From the National Heart and Lung Institute, Imperial College London, London SW32 6LY, United Kingdom
| | - Andrew Messer
- From the National Heart and Lung Institute, Imperial College London, London SW32 6LY, United Kingdom
| | - Ross Wilkinson
- From the National Heart and Lung Institute, Imperial College London, London SW32 6LY, United Kingdom
| | - Jordi Lopez Tremoleda
- the Medical Research Council Clinical Sciences Centre, Imperial College London, London W12 0NN, United Kingdom
| | - Michael D. Schneider
- From the National Heart and Lung Institute, Imperial College London, London SW32 6LY, United Kingdom
| | - Sian E. Harding
- From the National Heart and Lung Institute, Imperial College London, London SW32 6LY, United Kingdom
| | - Charles S. Redwood
- the Department of Cardiovascular Medicine, University of Oxford, Oxford OX3 9DU, United Kingdom
| | - Kieran Clarke
- the Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford OX1 3PT, United Kingdom
| | - Kristen Nowak
- the Center for Medical Research, University of Western Australia, Nedlands, Western Australia 6009, Australia
| | - Lorenzo Monserrat
- the Cardiology Department, Complejo Hospitalario Universitario Juan Canalejo, A Coruña 15006, Spain
| | - Dominic Wells
- the Centre for Neuroscience, Imperial College London, London W12 0NN, United Kingdom, and
| | - Steven B. Marston
- From the National Heart and Lung Institute, Imperial College London, London SW32 6LY, United Kingdom
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18
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How do mutations in contractile proteins cause the primary familial cardiomyopathies? J Cardiovasc Transl Res 2011; 4:245-55. [PMID: 21424860 DOI: 10.1007/s12265-011-9266-2] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/19/2010] [Accepted: 02/17/2011] [Indexed: 01/11/2023]
Abstract
In this article, the available evidence about the functional effects of the contractile protein mutations that cause hypertrophic cardiomyopathy (HCM) and dilated cardiomyopathy (DCM) is assessed. The molecular mechanism of the contractile apparatus of cardiac muscle and its regulation by Ca(2+) and PKA phosphorylation have been extensively studied. Therefore, when a number of point mutations in the contractile protein genes were found to cause the well-defined phenotypes of HCM and DCM, it was expected that the diseases could be explained at the molecular level. However, the search for a distinctive molecular phenotype did not yield rapid results. Now that a substantial number of mutations that cause HCM or DCM have been investigated in physiologically relevant systems and with a range of experimental techniques, a pattern is emerging. In the case of HCM, the hypothesis that the major effect of mutations is to increase myofibrillar Ca(2+)-sensitivity seems to be well established, but the mechanisms by which an increase in myofibrillar Ca(2+)-sensitivity induces hypertrophy remain obscure. In contrast, DCM mutations are not correlated with a specific effect on Ca(2+)-sensitivity. It has recently been proposed that DCM mutations uncouple troponin I phosphorylation from Ca(2+)-sensitivity changes, albeit based on only a few mutations so far. A plausible link between uncoupling and DCM has been proposed via blunting of the response to α-adrenergic stimulation.
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19
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Song W, Dyer E, Stuckey D, Leung MC, Memo M, Mansfield C, Ferenczi M, Liu K, Redwood C, Nowak K, Harding S, Clarke K, Wells D, Marston S. Investigation of a transgenic mouse model of familial dilated cardiomyopathy. J Mol Cell Cardiol 2010; 49:380-9. [DOI: 10.1016/j.yjmcc.2010.05.009] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/02/2009] [Revised: 05/17/2010] [Accepted: 05/18/2010] [Indexed: 11/25/2022]
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20
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Baker J, Riley G, Romero MR, Haynes AR, Hilton H, Simon M, Hancock J, Tateossian H, Ripoll VM, Blanco G. Identification of a Z-band associated protein complex involving KY, FLNC and IGFN1. Exp Cell Res 2010; 316:1856-70. [PMID: 20206623 DOI: 10.1016/j.yexcr.2010.02.027] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2009] [Revised: 02/11/2010] [Accepted: 02/24/2010] [Indexed: 12/21/2022]
Abstract
The KY protein underlies a form of muscular dystrophy in the mouse but its role in muscle remains elusive. Immunodetection of endogenous KY protein in C2C12-derived myotubes and expression of a recombinant form in neonatal cardiomyocytes indicated that KY is a Z-band associated protein. Moreover, characterization of a KY interacting protein fragment led to the identification of Igfn1 (Immunoglobulin-like and fibronectin type 3 domain containing 1). Igfn1 is a transcriptionally complex locus encoding many protein variants. A yeast two-hybrid screen identified the Z-band protein filamin C (FLNC) as an interacting partner. Consistent with this, expression of an IGFN1 recombinant fragment showed that the three N-terminal globular domains, common to at least five IGFN1 variants, are sufficient to provide Z-band targeting. Taken together, the yeast two-hybrid, biochemical and immunofluorescence data support the notion that KY, IGFN1 and FLNC are part of a Z-band associated protein complex likely to provide structural support to the skeletal muscle sarcomere.
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21
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Cardiomyopathy mutations reveal variable region of myosin converter as major element of cross-bridge compliance. Biophys J 2009; 97:806-24. [PMID: 19651039 DOI: 10.1016/j.bpj.2009.05.023] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2008] [Revised: 05/05/2009] [Accepted: 05/08/2009] [Indexed: 11/23/2022] Open
Abstract
The ability of myosin to generate motile forces is based on elastic distortion of a structural element of the actomyosin complex (cross-bridge) that allows strain to develop before filament sliding. Addressing the question, which part of the actomyosin complex experiences main elastic distortion, we suggested previously that the converter domain might be the most compliant region of the myosin head domain. Here we test this proposal by studying functional effects of naturally occurring missense mutations in the beta-myosin heavy chain, 723Arg --> Gly (R723G) and 736Ile --> Thr (I736T), in comparison to 719Arg --> Trp (R719W). All three mutations are associated with hypertrophic cardiomyopathy and are located in the converter region of the myosin head domain. We determined several mechanical parameters of single skinned slow fibers isolated from Musculus soleus biopsies of hypertrophic cardiomyopathy patients and healthy controls. Major findings of this study for mutation R723G were i), a >40% increase in fiber stiffness in rigor with a 2.9-fold increase in stiffness per myosin head (S( *)(rigor R723G) = 0.84 pN/nm S( *)(rigor WT) = 0.29 pN/nm); and ii), a significant increase in force per head (F( *)(10 degrees C), 1.99 pN vs. 1.49 pN = 1.3-fold increase; F( *)(20 degrees C), 2.56 pN vs. 1.92 pN = 1.3-fold increase) as well as stiffness per head during isometric steady-state contraction (S( *)(active10 degrees C), 0.52 pN/nm vs. 0.28 pN/nm = 1.9-fold increase). Similar changes were found for mutation R719W (2.6-fold increase in S( *)(rigor); 1.8-fold increase in F( *)(10 degrees C), 1.6-fold in F( *)(20 degrees C); twofold increase in S( *)(active10 degrees C)). Changes in active cross-bridge cycling kinetics could not account for the increase in force and active stiffness. For the above estimates the previously determined fraction of mutated myosin in the biopsies was taken into account. Data for wild-type myosin of slow soleus muscle fibers support previous findings that for the slow myosin isoform S( *) and F( *) are significantly lower than for fast myosin e.g., of rabbit psoas muscle. The data indicate that two mutations, R723G and R719W, are associated with an increase in resistance to elastic distortion of the individual mutated myosin heads whereas mutation I736T has essentially no effect. The data strongly support the notion that major elastic distortion occurs within the converter itself. Apparently, the compliance depends on specific residues, e.g., R719 and R723, presumably located at strategic positions near the long alpha-helix of the light chain binding domain. Because amino acids 719 and 723 are nonconserved residues, cross-bridge stiffness may well be specifically tuned for different myosins.
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Dyer EC, Jacques AM, Hoskins AC, Ward DG, Gallon CE, Messer AE, Kaski JP, Burch M, Kentish JC, Marston SB. Functional analysis of a unique troponin c mutation, GLY159ASP, that causes familial dilated cardiomyopathy, studied in explanted heart muscle. Circ Heart Fail 2009; 2:456-64. [PMID: 19808376 DOI: 10.1161/circheartfailure.108.818237] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Familial dilated cardiomyopathy can be caused by mutations in the proteins of the muscle thin filament. In vitro, these mutations decrease Ca(2+) sensitivity and cross-bridge turnover rate, but the mutations have not been investigated in human tissue. We studied the Ca(2+)-regulatory properties of myocytes and troponin extracted from the explanted heart of a patient with inherited dilated cardiomyopathy due to the cTnC G159D mutation. METHODS AND RESULTS Mass spectroscopy showed that the mutant cTnC was expressed approximately equimolar with wild-type cTnC. Contraction was compared in skinned ventricular myocytes from the cTnC G159D patient and nonfailing donor heart. Maximal Ca(2+)-activated force was similar in cTnC G159D and donor myocytes, but the Ca(2+) sensitivity of cTnC G159D myocytes was higher (EC(50) G159D/donor=0.60). Thin filaments reconstituted with skeletal muscle actin and human cardiac tropomyosin and troponin were studied by in vitro motility assay. Thin filaments containing the mutation had a higher Ca(2+) sensitivity (EC(50) G159D/donor=0.55 + or - 0.13), whereas the maximally activated sliding speed was unaltered. In addition, the cTnC G159D mutation blunted the change in Ca(2+) sensitivity when TnI was dephosphorylated. With wild-type troponin, Ca(2+) sensitivity was increased (EC(50) P/unP=4.7 + or - 1.9) but not with cTnC G159D troponin (EC(50) P/unP=1.2 + or - 0.1). CONCLUSIONS We propose that uncoupling of the relationship between phosphorylation and Ca(2+) sensitivity could be the cause of the dilated cardiomyopathy phenotype. The differences between these data and previous in vitro results show that native phosphorylation of troponin I and troponin T and other posttranslational modifications of sarcomeric proteins strongly influence the functional effects of a mutation.
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Becker E, Navarro-López F, Francino A, Brenner B, Kraft T. Quantification of mutant versus wild-type myosin in human muscle biopsies using nano-LC/ESI-MS. Anal Chem 2007; 79:9531-8. [PMID: 18020371 DOI: 10.1021/ac701711h] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A liquid chromatography/electrospray ionization mass spectrometry (nano-LC/ESI-MS) approach is described by which abundance of proteins (e.g., of beta-myosin heavy chain; MW 223 kDa) carrying a point mutation can be determined in tissue samples where the mutant protein is coexpressed with its wild-type forms. After enzymatic cleavage of the extracted parent protein, mutant and wild-type species of the peptide with the locus of the point mutation were quantified. Synthetic peptides, identical to wild-type and mutant peptides but labeled with stable isotopes ((13)C, (15)N), were added in known amounts as internal standards. The peak areas obtained by MS for the stable-isotope-labeled peptides and for the native peptides were used for quantification. To demonstrate the suitability of this approach we determined the relative abundance of beta-myosin with the Arg723Gly exchange in muscle biopsies of patients with Familial Hypertrophic Cardiomyopathy (HCM). For two such patients the fraction of mutated myosin was 62%, i.e., significantly different from 50%, which is quite unexpected for an autosomal dominant disease in heterozygous patients. Correlation between abundance of mutant myosin and clinical malignancy seen for several mutations in the myosin head domain emphasizes the relevance of such quantification. The approach for quantification described here is generally applicable for quantification of proteins with single point mutations even if only small amounts of tissue are available.
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Affiliation(s)
- Edgar Becker
- Molecular and Cell Physiology, Medical School Hannover, Carl-Neuberg-Strasse 1, D-30625 Hannover, Germany
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Owen JS, Bharadwaj MS, Thomas MJ, Bhat S, Samuel MP, Sorci-Thomas MG. Ratio determination of plasma wild-type and L159R apoA-I using mass spectrometry: tools for studying apoA-IFin. J Lipid Res 2007; 48:226-34. [PMID: 17071967 DOI: 10.1194/jlr.d600031-jlr200] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In this report, methods are described to isolate milligram quantities of a mutant apolipoprotein A-I (apoA-I) protein for use in structure-function studies. Expression of the L159R apoA-I mutation in humans reduces the concentration of plasma wild-type apoA-I, thus displaying a dominant negative phenotype in vivo. Earlier attempts to express and isolate this mutant protein resulted in extensive degradation and protein misfolding. Using an Escherichia coli expression system used predominantly for the isolation of soluble apoA-I mutant proteins, we describe the expression and purification of L159R apoA-I (apoA-I(Fin)) from inclusion bodies. In addition, we describe a mass spectrometric method for measuring the L159R-to-wild-type apoA-I ratio in a 1 microl plasma sample. These new methods will facilitate further studies into the mechanism behind the dominant negative phenotype associated with the expression of the L159R apoA-I protein in humans.
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Affiliation(s)
- John S Owen
- Department of Biochemistry, Center for Lipid Science, Wake Forest University Medical Center, Winston-Salem, NC 27101, USA
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25
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John H, Hierer J, Haas O, Forssmann WG. Quantification of angiotensin-converting-enzyme-mediated degradation of human chemerin 145-154 in plasma by matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry. Anal Biochem 2006; 362:117-25. [PMID: 17240345 DOI: 10.1016/j.ab.2006.12.001] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2006] [Revised: 11/27/2006] [Accepted: 12/04/2006] [Indexed: 12/26/2022]
Abstract
Chemerin is a chemoattractive protein acting as a ligand for the G-protein-coupled receptor ChemR23/CMKLR1 and plays an important role in the innate and adaptive immunity. Proteolytic processing of its C terminus is essential for receptor binding and physiological activity. Therefore, we investigated the plasma stability of the decapeptide chemerin 145-154 (P(145)-F(154)) corresponding to the C terminus of the physiologically active chemerin variant E(21)-F(154) from human hemofiltrate. For monitoring concentration-time profiles and degradation products we developed a novel matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry procedure using an internal peptide standard (hemorphin LVV-H7) for quantification. The linear range covers 2.5 orders of magnitude in the lower micromolar concentration range (lower limit of quantification 0.312 microg/ml, 0.25 microM) characterized by satisfactory reproducibility (CV < or =9%), accuracy (< or =10%), ruggedness, and recovery (98%). We found that chemerin 145-154 is C-terminally truncated in human citrate plasma by the cleavage of the penultimate dipeptidyl residue. N-terminal truncation was not observed. In contrast to citrate plasma, no degradation was detected in ethylenediammetetraacetate (EDTA) plasma. We identified angiotensin-converting-enzyme (ACE) to be responsible for C-terminal truncation, which could be completely inhibited by EDTA and captopril. These results are relevant to clarify the natural processing of chemerin and the potential involvement of ACE in mediating the immune response.
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Affiliation(s)
- Harald John
- IPF PharmaCeuticals GmbH, Feodor-Lynen-Str. 31, D-30625 Hannover, Germany.
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26
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27
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Sanbe A, James J, Tuzcu V, Nas S, Martin L, Gulick J, Osinska H, Sakthivel S, Klevitsky R, Ginsburg KS, Bers DM, Zinman B, Lakatta EG, Robbins J. Transgenic rabbit model for human troponin I-based hypertrophic cardiomyopathy. Circulation 2005; 111:2330-8. [PMID: 15867176 PMCID: PMC1314982 DOI: 10.1161/01.cir.0000164234.24957.75] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Transgenic and gene-targeted models have focused on the mouse. Fundamental differences between the mouse and human exist in Ca2+ handling during contraction/relaxation and in alterations in Ca2+ flux during heart failure, with the rabbit more accurately reflecting the human system. METHODS AND RESULTS Cardiac troponin I (cTnI) mutations can cause familial hypertrophic cardiomyopathy. An inhibitory domain mutation, arginine146-->glycine (cTnI(146Gly)), was modeled with the use of transgenic expression in the rabbit ventricle. cTnI(146Gly) levels >40% of total cTnI were perinatally lethal, whereas replacement levels of 15% to 25% were well tolerated. cTnI(146Gly) expression led to a leftward shift in the force-pCa2+ curves with cardiomyocyte disarray, fibrosis, and altered connexin43 organization. In isolated cTnI(146Gly) myocytes, twitch relaxation amplitudes were smaller than in normal cells, but [Ca]i transients and sarcoplasmic reticulum Ca2+ load were not different. Detrended fluctuation analysis of the QT(max) intervals was used to evaluate the cardiac repolarization phase and showed a significantly higher scaling exponent in the transgenic animals. CONCLUSIONS Expression of modest amounts of cTnI(146Gly) led to subtle defects without severely affecting cardiac function. Aberrant connexin organization, subtle morphological deficits, and an altered fractal pattern of the repolarization phase of transgenic rabbits, in the absence of entropy or other ECG abnormalities, may indicate an early developing pathology before the onset of more obvious repolarization abnormalities or major alterations in cardiac mechanics.
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MESH Headings
- Animals
- Animals, Genetically Modified
- Calcium/metabolism
- Cardiomegaly
- Cardiomyopathy, Hypertrophic, Familial/genetics
- Cardiomyopathy, Hypertrophic, Familial/pathology
- Cardiomyopathy, Hypertrophic, Familial/physiopathology
- Connexin 43/metabolism
- Disease Models, Animal
- Electrocardiography
- Fibrosis
- Heart Function Tests
- Heart Ventricles/metabolism
- Humans
- Mutation, Missense
- Myocytes, Cardiac/pathology
- Phenotype
- Rabbits
- Transgenes
- Troponin I/genetics
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | | | - Jeffrey Robbins
- Correspondence to: Jeffrey Robbins, Division of Molecular Cardiovascular Biology, 3333 Burnet Avenue, Cincinnati, OH 45229-3039. Tel.: 513-636-8098; Fax: 513-636-3852;
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Kirschner SE, Becker E, Antognozzi M, Kubis HP, Francino A, Navarro-López F, Bit-Avragim N, Perrot A, Mirrakhimov MM, Osterziel KJ, McKenna WJ, Brenner B, Kraft T. Hypertrophic cardiomyopathy-related beta-myosin mutations cause highly variable calcium sensitivity with functional imbalances among individual muscle cells. Am J Physiol Heart Circ Physiol 2004; 288:H1242-51. [PMID: 15550524 DOI: 10.1152/ajpheart.00686.2004] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Disease-causing mutations in cardiac myosin heavy chain (beta-MHC) are identified in about one-third of families with hypertrophic cardiomyopathy (HCM). The effect of myosin mutations on calcium sensitivity of the myofilaments, however, is largely unknown. Because normal and mutant cardiac MHC are also expressed in slow-twitch skeletal muscle, which is more easily accessible and less subject to the adaptive responses seen in myocardium, we compared the calcium sensitivity (pCa(50)) and the steepness of force-pCa relations (cooperativity) of single soleus muscle fibers from healthy individuals and from HCM patients of three families with selected myosin mutations. Fibers with the Arg723Gly and Arg719Trp mutations showed a decrease in mean pCa(50), whereas those with the Ile736Thr mutation showed slightly increased mean pCa(50) with higher active forces at low calcium concentrations and residual active force even under relaxing conditions. In addition, there was a marked variability in pCa(50) between individual fibers carrying the same mutation ranging from an almost normal response to highly significant differences that were not observed in controls. While changes in mean pCa(50) may suggest specific pharmacological treatment (e.g., calcium antagonists), the observed large functional variability among individual muscle cells might negate such selective treatment. More importantly, the variability in pCa(50) from fiber to fiber is likely to cause imbalances in force generation and be the primary cause for contractile dysfunction and development of disarray in the myocardium.
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29
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Karadag A, Riminucci M, Bianco P, Cherman N, Kuznetsov SA, Nguyen N, Collins MT, Robey PG, Fisher LW. A novel technique based on a PNA hybridization probe and FRET principle for quantification of mutant genotype in fibrous dysplasia/McCune-Albright syndrome. Nucleic Acids Res 2004; 32:e63. [PMID: 15096559 PMCID: PMC407839 DOI: 10.1093/nar/gnh059] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Somatic mutations are present in various proportions in numerous developmental pathologies. Somatic activating missense mutations of the GNAS gene encoding the Gs(alpha) protein have previously been shown to be the cause of fibrous dysplasia of bone (FD)/McCune-Albright syndrome (MAS). Because in MAS patients, tissues as diverse as melanocytes, gonads and bone are affected, it is generally accepted that the GNAS mutation in this disease must have occurred early in development. Interestingly, it has been shown that the development of an active FD lesion may require both normal and mutant cells. Studies of the somatic mosaic states of FD/MAS and many other somatic diseases need an accurate method to determine the ratio of mutant to normal cells in a given tissue. A new method for quantification of the mutant:normal ratio of cells using a PNA hybridization probe-based FRET technique was developed. This novel technique, with a linear sensitivity of 2.5% mutant alleles, was used to detect the percentage mutant cells in a number of tissue and cell culture samples derived from FD/MAS lesions and could easily be adapted for the quantification of mutations in a large spectrum of diseases including cancer.
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Affiliation(s)
- Abdullah Karadag
- Craniofacial and Skeletal Diseases Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Department of Health and Human Services, Bethesda, MD 20892-4320, USA.
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30
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Köhler J, Winkler G, Schulte I, Scholz T, McKenna W, Brenner B, Kraft T. Mutation of the myosin converter domain alters cross-bridge elasticity. Proc Natl Acad Sci U S A 2002; 99:3557-62. [PMID: 11904418 PMCID: PMC122562 DOI: 10.1073/pnas.062415899] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Elastic distortion of a structural element of the actomyosin complex is fundamental to the ability of myosin to generate motile forces. An elastic element allows strain to develop within the actomyosin complex (cross-bridge) before movement. Relief of this strain then drives filament sliding, or more generally, movement of a cargo. Even with the known crystal structure of the myosin head, however, the structural element of the actomyosin complex in which elastic distortion occurs remained unclear. To assign functional relevance to various structural elements of the myosin head, e.g., to identify the elastic element within the cross-bridge, we studied mechanical properties of muscle fibers from patients with familial hypertrophic cardiomyopathy with point mutations in the head domain of the beta-myosin heavy chain. We found that the Arg-719 --> Trp (Arg719Trp) mutation, which is located in the converter domain of the myosin head fragment, causes an increase in force generation and fiber stiffness under isometric conditions by 48-59%. Under rigor and relaxing conditions, fiber stiffness was 45-47% higher than in control fibers. Yet, kinetics of active cross-bridge cycling were unchanged. These findings, especially the increase in fiber stiffness under rigor conditions, indicate that cross-bridges with the Arg719Trp mutation are more resistant to elastic distortion. The data presented here strongly suggest that the converter domain that forms the junction between the catalytic and the light-chain-binding domain of the myosin head is not only essential for elastic distortion of the cross-bridge, but that the main elastic distortion may even occur within the converter domain itself.
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MESH Headings
- Cardiomyopathy, Hypertrophic, Familial/genetics
- Cardiomyopathy, Hypertrophic, Familial/metabolism
- Cardiomyopathy, Hypertrophic, Familial/physiopathology
- Catalytic Domain
- Elasticity
- Female
- Humans
- Isometric Contraction
- Microscopy, Confocal
- Models, Molecular
- Muscle Fibers, Skeletal/chemistry
- Muscle Fibers, Skeletal/metabolism
- Muscle Fibers, Skeletal/ultrastructure
- Muscle Relaxation
- Muscle, Skeletal/chemistry
- Muscle, Skeletal/metabolism
- Muscle, Skeletal/ultrastructure
- Mutation/genetics
- Myosin Heavy Chains/chemistry
- Myosin Heavy Chains/genetics
- Myosin Heavy Chains/metabolism
- Myosin Heavy Chains/ultrastructure
- Pliability
- Protein Structure, Tertiary
- Solutions
- X-Ray Diffraction
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Affiliation(s)
- Jan Köhler
- Molekular- und Zellphysiologie, Medizinische Hochschule, D-30625 Hannover, Germany
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