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Morck MM, Bhowmik D, Pathak D, Dawood A, Spudich J, Ruppel KM. Hypertrophic cardiomyopathy mutations in the pliant and light chain-binding regions of the lever arm of human β-cardiac myosin have divergent effects on myosin function. eLife 2022; 11:e76805. [PMID: 35767336 PMCID: PMC9242648 DOI: 10.7554/elife.76805] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Accepted: 06/12/2022] [Indexed: 11/13/2022] Open
Abstract
Mutations in the lever arm of β-cardiac myosin are a frequent cause of hypertrophic cardiomyopathy, a disease characterized by hypercontractility and eventual hypertrophy of the left ventricle. Here, we studied five such mutations: three in the pliant region of the lever arm (D778V, L781P, and S782N) and two in the light chain-binding region (A797T and F834L). We investigated their effects on both motor function and myosin subfragment 2 (S2) tail-based autoinhibition. The pliant region mutations had varying effects on the motor function of a myosin construct lacking the S2 tail: overall, D778V increased power output, L781P reduced power output, and S782N had little effect on power output, while all three reduced the external force sensitivity of the actin detachment rate. With a myosin containing the motor domain and the proximal S2 tail, the pliant region mutations also attenuated autoinhibition in the presence of filamentous actin but had no impact in the absence of actin. By contrast, the light chain-binding region mutations had little effect on motor activity but produced marked reductions in autoinhibition in both the presence and absence of actin. Thus, mutations in the lever arm of β-cardiac myosin have divergent allosteric effects on myosin function, depending on whether they are in the pliant or light chain-binding regions.
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Affiliation(s)
- Makenna M Morck
- Stanford Cardiovascular Institute, Stanford University School of MedicineStanfordUnited States
- Department of Biochemistry, Stanford University School of MedicineStanfordUnited States
| | - Debanjan Bhowmik
- Stanford Cardiovascular Institute, Stanford University School of MedicineStanfordUnited States
- Department of Biochemistry, Stanford University School of MedicineStanfordUnited States
| | - Divya Pathak
- Stanford Cardiovascular Institute, Stanford University School of MedicineStanfordUnited States
- Department of Biochemistry, Stanford University School of MedicineStanfordUnited States
| | - Aminah Dawood
- Stanford Cardiovascular Institute, Stanford University School of MedicineStanfordUnited States
- Department of Biochemistry, Stanford University School of MedicineStanfordUnited States
| | - James Spudich
- Stanford Cardiovascular Institute, Stanford University School of MedicineStanfordUnited States
- Department of Biochemistry, Stanford University School of MedicineStanfordUnited States
| | - Kathleen M Ruppel
- Stanford Cardiovascular Institute, Stanford University School of MedicineStanfordUnited States
- Department of Biochemistry, Stanford University School of MedicineStanfordUnited States
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2
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Bang ML, Bogomolovas J, Chen J. Understanding the molecular basis of cardiomyopathy. Am J Physiol Heart Circ Physiol 2022; 322:H181-H233. [PMID: 34797172 PMCID: PMC8759964 DOI: 10.1152/ajpheart.00562.2021] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Revised: 11/16/2021] [Accepted: 11/16/2021] [Indexed: 02/03/2023]
Abstract
Inherited cardiomyopathies are a major cause of mortality and morbidity worldwide and can be caused by mutations in a wide range of proteins located in different cellular compartments. The present review is based on Dr. Ju Chen's 2021 Robert M. Berne Distinguished Lectureship of the American Physiological Society Cardiovascular Section, in which he provided an overview of the current knowledge on the cardiomyopathy-associated proteins that have been studied in his laboratory. The review provides a general summary of the proteins in different compartments of cardiomyocytes associated with cardiomyopathies, with specific focus on the proteins that have been studied in Dr. Chen's laboratory.
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Affiliation(s)
- Marie-Louise Bang
- Institute of Genetic and Biomedical Research (IRGB), National Research Council (CNR), Milan Unit, Milan, Italy
- IRCCS Humanitas Research Hospital, Rozzano (Milan), Italy
| | - Julius Bogomolovas
- Division of Cardiovascular Medicine, Department of Medicine Cardiology, University of California, San Diego, La Jolla, California
| | - Ju Chen
- Division of Cardiovascular Medicine, Department of Medicine Cardiology, University of California, San Diego, La Jolla, California
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3
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Pathogenic Intronic Splice-Affecting Variants in MYBPC3 in Three Patients with Hypertrophic Cardiomyopathy. CARDIOGENETICS 2021. [DOI: 10.3390/cardiogenetics11020009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Genetic variants in MYBPC3 are one of the most common causes of hypertrophic cardiomyopathy (HCM). While variants in MYBPC3 affecting canonical splice site dinucleotides are a well-characterised cause of HCM, only recently has work begun to investigate the pathogenicity of more deeply intronic variants. Here, we present three patients with HCM and intronic splice-affecting MYBPC3 variants and analyse the impact of variants on splicing using in vitro minigene assays. We show that the three variants, a novel c.927-8G>A variant and the previously reported c.1624+4A>T and c.3815-10T>G variants, result in MYBPC3 splicing errors. Analysis of blood-derived patient RNA for the c.3815-10T>G variant revealed only wild type spliced product, indicating that mis-spliced transcripts from the mutant allele are degraded. These data indicate that the c.927-8G>A variant of uncertain significance and likely benign c.3815-10T>G should be reclassified as likely pathogenic. Furthermore, we find shortcomings in commonly applied bioinformatics strategies to prioritise variants impacting MYBPC3 splicing and re-emphasise the need for functional assessment of variants of uncertain significance in diagnostic testing.
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Rasicci DV, Kirkland O, Moonschi FH, Wood NB, Szczesna-Cordary D, Previs MJ, Wenk JF, Campbell KS, Yengo CM. Impact of regulatory light chain mutation K104E on the ATPase and motor properties of cardiac myosin. J Gen Physiol 2021; 153:212025. [PMID: 33891674 PMCID: PMC8077168 DOI: 10.1085/jgp.202012811] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Accepted: 03/19/2021] [Indexed: 12/11/2022] Open
Abstract
Mutations in the cardiac myosin regulatory light chain (RLC, MYL2 gene) are known to cause inherited cardiomyopathies with variable phenotypes. In this study, we investigated the impact of a mutation in the RLC (K104E) that is associated with hypertrophic cardiomyopathy (HCM). Previously in a mouse model of K104E, older animals were found to develop cardiac hypertrophy, fibrosis, and diastolic dysfunction, suggesting a slow development of HCM. However, variable penetrance of the mutation in human populations suggests that the impact of K104E may be subtle. Therefore, we generated human cardiac myosin subfragment-1 (M2β-S1) and exchanged on either the wild type (WT) or K104E human ventricular RLC in order to assess the impact of the mutation on the mechanochemical properties of cardiac myosin. The maximum actin-activated ATPase activity and actin sliding velocities in the in vitro motility assay were similar in M2β-S1 WT and K104E, as were the detachment kinetic parameters, including the rate of ATP-induced dissociation and the ADP release rate constant. We also examined the mechanical performance of α-cardiac myosin extracted from transgenic (Tg) mice expressing human wild type RLC (Tg WT) or mutant RLC (Tg K104E). We found that α-cardiac myosin from Tg K104E animals demonstrated enhanced actin sliding velocities in the motility assay compared with its Tg WT counterpart. Furthermore, the degree of incorporation of the mutant RLC into α-cardiac myosin in the transgenic animals was significantly reduced compared with wild type. Therefore, we conclude that the impact of the K104E mutation depends on either the length or the isoform of the myosin heavy chain backbone and that the mutation may disrupt RLC interactions with the myosin lever arm domain.
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Affiliation(s)
- David V Rasicci
- Pennsylvania State University College of Medicine, Hershey, PA
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Schmid M, Toepfer CN. Cardiac myosin super relaxation (SRX): a perspective on fundamental biology, human disease and therapeutics. Biol Open 2021; 10:10/2/bio057646. [PMID: 33589442 PMCID: PMC7904003 DOI: 10.1242/bio.057646] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The fundamental basis of muscle contraction 'the sliding filament model' (Huxley and Niedergerke, 1954; Huxley and Hanson, 1954) and the 'swinging, tilting crossbridge-sliding filament mechanism' (Huxley, 1969; Huxley and Brown, 1967) nucleated a field of research that has unearthed the complex and fascinating role of myosin structure in the regulation of contraction. A recently discovered energy conserving state of myosin termed the super relaxed state (SRX) has been observed in filamentous myosins and is central to modulating force production and energy use within the sarcomere. Modulation of myosin function through SRX is a rapidly developing theme in therapeutic development for both cardiovascular disease and infectious disease. Some 70 years after the first discoveries concerning muscular function, modulation of myosin SRX may bring the first myosin targeted small molecule to the clinic, for treating hypertrophic cardiomyopathy (Olivotto et al., 2020). An often monogenic disease HCM afflicts 1 in 500 individuals, and can cause heart failure and sudden cardiac death. Even as we near therapeutic translation, there remain many questions about the governance of muscle function in human health and disease. With this review, we provide a broad overview of contemporary understanding of myosin SRX, and explore the complexities of targeting this myosin state in human disease.This article has an associated Future Leaders to Watch interview with the authors of the paper.
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Affiliation(s)
- Manuel Schmid
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford OX3 9DU, UK
| | - Christopher N Toepfer
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford OX3 9DU, UK
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
- Wellcome Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
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6
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Ng H, Becirovic Agic M, Hultström M, Isackson H. Optimal cutting temperature medium embedding and cryostat sectioning are valid for cardiac myofilament function assessment. Am J Physiol Heart Circ Physiol 2020; 319:H235-H241. [PMID: 32469635 DOI: 10.1152/ajpheart.00194.2020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
To maximize data obtainment from valuable cardiac tissue, we hypothesized that myocardium fixed in optimal cutting temperature (OCT) medium for histology could also be used to investigate the function of myofilament proteins in situ. We compared tissue prepared via conventional liquid nitrogen (LN) snap freezing with tissue fixed in OCT and then sectioned in fiber-parallel orientation. We found that actin-myosin Ca2+ sensitivity, activation rate by Ca2+, cooperativity along the thin filament, as well as cross-bridge cycling rate were unaffected by OCT storage and could reliably be interpreted after sectioning. Absolute values in maximum force generation per cross-sectional area, as well as passive strain, are difficult to investigate after sectioning, as myofibrillar continuity along the preparation cannot be guaranteed. We have shown that myocardial tissue stored in OCT and sectioned before analysis is available for functional analysis, a valuable means of maximizing usage of precious cardiac biopsies.NEW & NOTEWORTHY Myocardial tissue in optimal cutting temperature (OCT) fixation and cryostat sectioning was tested as a means of storing and preparing tissue for myofilament function analysis in relation to conventional liquid nitrogen freezing and dissection. Actomyosin interaction, Ca2+ force activation, and passive compliance were tested. The study concluded that OCT storage and cryostat sectioning do not interfere with the actomyosin cross-bridge dynamics or Ca2+ activation but that absolute tension values suffer and may not be investigated by this method.
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Affiliation(s)
- Henry Ng
- Department of Medical Cell Biology, Integrative Physiology, Uppsala University, Uppsala Sweden
| | - Mediha Becirovic Agic
- Department of Medical Cell Biology, Integrative Physiology, Uppsala University, Uppsala Sweden
| | - Michael Hultström
- Department of Medical Cell Biology, Integrative Physiology, Uppsala University, Uppsala Sweden.,Department of Surgical Sciences, Anaesthesia and Intensive Care Medicine, Uppsala University, Uppsala, Sweden
| | - Henrik Isackson
- Department of Medical Cell Biology, Integrative Physiology, Uppsala University, Uppsala Sweden.,Department of Medical Sciences, Cardiology, Uppsala University, Uppsala, Sweden
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Yadav S, Sitbon YH, Kazmierczak K, Szczesna-Cordary D. Hereditary heart disease: pathophysiology, clinical presentation, and animal models of HCM, RCM, and DCM associated with mutations in cardiac myosin light chains. Pflugers Arch 2019; 471:683-699. [PMID: 30706179 DOI: 10.1007/s00424-019-02257-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Revised: 12/26/2018] [Accepted: 01/13/2019] [Indexed: 02/07/2023]
Abstract
Genetic cardiomyopathies, a group of cardiovascular disorders based on ventricular morphology and function, are among the leading causes of morbidity and mortality worldwide. Such genetically driven forms of hypertrophic (HCM), dilated (DCM), and restrictive (RCM) cardiomyopathies are chronic, debilitating diseases that result from biomechanical defects in cardiac muscle contraction and frequently progress to heart failure (HF). Locus and allelic heterogeneity, as well as clinical variability combined with genetic and phenotypic overlap between different cardiomyopathies, have challenged proper clinical prognosis and provided an incentive for identification of pathogenic variants. This review attempts to provide an overview of inherited cardiomyopathies with a focus on their genetic etiology in myosin regulatory (RLC) and essential (ELC) light chains, which are EF-hand protein family members with important structural and regulatory roles. From the clinical discovery of cardiomyopathy-linked light chain mutations in patients to an array of exploratory studies in animals, and reconstituted and recombinant systems, we have summarized the current state of knowledge on light chain mutations and how they induce physiological disease states via biochemical and biomechanical alterations at the molecular, tissue, and organ levels. Cardiac myosin RLC phosphorylation and the N-terminus ELC have been discussed as two important emerging modalities with important implications in the regulation of myosin motor function, and thus cardiac performance. A comprehensive understanding of such triggers is absolutely necessary for the development of target-specific rescue strategies to ameliorate or reverse the effects of myosin light chain-related inherited cardiomyopathies.
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MESH Headings
- Animals
- Cardiomyopathy, Dilated/etiology
- Cardiomyopathy, Dilated/genetics
- Cardiomyopathy, Dilated/pathology
- Cardiomyopathy, Hypertrophic/etiology
- Cardiomyopathy, Hypertrophic/genetics
- Cardiomyopathy, Hypertrophic/pathology
- Cardiomyopathy, Restrictive/etiology
- Cardiomyopathy, Restrictive/genetics
- Cardiomyopathy, Restrictive/pathology
- Disease Models, Animal
- Humans
- Mutation
- Myosin Light Chains/genetics
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Affiliation(s)
- Sunil Yadav
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, 1600 NW 10th Ave., Miami, FL, 33136, USA
| | - Yoel H Sitbon
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, 1600 NW 10th Ave., Miami, FL, 33136, USA
| | - Katarzyna Kazmierczak
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, 1600 NW 10th Ave., Miami, FL, 33136, USA
| | - Danuta Szczesna-Cordary
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, 1600 NW 10th Ave., Miami, FL, 33136, USA.
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8
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Guhathakurta P, Prochniewicz E, Roopnarine O, Rohde JA, Thomas DD. A Cardiomyopathy Mutation in the Myosin Essential Light Chain Alters Actomyosin Structure. Biophys J 2017; 113:91-100. [PMID: 28700929 DOI: 10.1016/j.bpj.2017.05.027] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Revised: 05/16/2017] [Accepted: 05/17/2017] [Indexed: 01/01/2023] Open
Abstract
We have used site-directed time-resolved fluorescence resonance energy transfer to determine the effect of a pathological mutation in the human ventricular essential light chain (hVELC) of myosin, on the structural dynamics of the actin-myosin complex. The hVELC modulates the function of actomyosin, through the interaction of its N-terminal extension with actin and its C-terminal lobe with the myosin heavy chain. Several mutations in hVELC are associated with hypertrophic cardiomyopathy (HCM). Some biochemical effects of these mutations are known, but further insight is needed about their effects on the structural dynamics of functioning actomyosin. Therefore, we introduced the HCM mutation E56G into a single-cysteine (C16) hVELC construct and substituted it for the VELC of bovine cardiac myosin subfragment 1. Using a donor fluorescent probe on actin (at C374) and an acceptor probe on C16 of hVELC, we performed time-resolved fluorescence resonance energy transfer, directly detecting structural changes within the bound actomyosin complex during function. The E56G mutation has no significant effect on actin-activated ATPase activity or actomyosin affinity in the presence of ATP, or on the structure of the strong-binding S complex in the absence of ATP. However, in the presence of saturating ATP, where both W (prepowerstroke) and S (postpowerstroke) structural states are observed, the mutant increases the mole fraction of the S complex (increasing the duty ratio), while shifting the structure of the remaining W complex toward that of S, indicating a structural redistribution toward the strongly bound (force-generating) complex. We propose that this effect is responsible for the hypercontractile phenotype induced by this HCM mutation in myosin.
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Affiliation(s)
- Piyali Guhathakurta
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota
| | - Ewa Prochniewicz
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota
| | - Osha Roopnarine
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota
| | - John A Rohde
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota
| | - David D Thomas
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota.
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9
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Zhou Z, Huang W, Liang J, Szczesna-Cordary D. Molecular and Functional Effects of a Splice Site Mutation in the MYL2 Gene Associated with Cardioskeletal Myopathy and Early Cardiac Death in Infants. Front Physiol 2016; 7:240. [PMID: 27378946 PMCID: PMC4911367 DOI: 10.3389/fphys.2016.00240] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2016] [Accepted: 06/03/2016] [Indexed: 12/26/2022] Open
Abstract
The homozygous appearance of the intronic mutation (IVS6-1) in the MYL2 gene encoding for myosin ventricular/slow-twitch skeletal regulatory light chain (RLC) was recently linked to the development of slow skeletal muscle fiber type I hypotrophy and early cardiac death. The IVS6-1 (c403-1G>C) mutation resulted from a cryptic splice site in MYL2 causing a frameshift and replacement of the last 32 codons by 19 different amino acids in the RLC mutant protein. Infants who were IVS6-1+∕+-positive died between 4 and 6 months of age due to cardiomyopathy and heart failure. In this report we have investigated the molecular mechanism and functional consequences associated with the IVS6-1 mutation using recombinant human cardiac IVS6-1 and wild-type (WT) RLC proteins. Recombinant proteins were reconstituted into RLC-depleted porcine cardiac muscle preparations and subjected to enzymatic and functional assays. IVS6-1-RLC showed decreased binding to the myosin heavy chain (MHC) compared with WT, and IVS6-1-reconstituted myosin displayed reduced binding to actin in rigor. The IVS6-1 myosin demonstrated a significantly lower Vmax of the actin-activated myosin ATPase activity compared with WT. In stopped-flow experiments, IVS6-1 myosin showed slower kinetics of the ATP induced dissociation of the acto-myosin complex and a significantly reduced slope of the kobs-[MgATP] relationship compared to WT. In skinned porcine cardiac muscles, RLC-depleted and IVS6-1 reconstituted muscle strips displayed a significant decrease in maximal contractile force and a significantly increased Ca2+ sensitivity, both hallmarks of hypertrophic cardiomyopathy-associated mutations in MYL2. Our results showed that the amino-acid changes in IVS6-1 were sufficient to impose significant conformational alterations in the RLC protein and trigger a series of abnormal protein-protein interactions in the cardiac muscle sarcomere. Notably, the mutation disrupted the RLC-MHC interaction and the steady-state and kinetics of the acto-myosin interaction. Specifically, slower myosin cross-bridge turnover rates and slower second-order MgATP binding rates of acto-myosin interactions were observed in IVS6-1 vs. WT reconstituted cardiac preparations. Our in vitro results suggest that when placed in vivo, IVS6-1 may lead to cardiomyopathy and early death of homozygous infants by severely compromising the ability of myosin to develop contractile force and maintain normal systolic and diastolic cardiac function.
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Affiliation(s)
- Zhiqun Zhou
- Department of Molecular and Cellular Pharmacology, University of Miami Leonard M. Miller School of Medicine Miami, FL, USA
| | - Wenrui Huang
- Department of Molecular and Cellular Pharmacology, University of Miami Leonard M. Miller School of Medicine Miami, FL, USA
| | - Jingsheng Liang
- Department of Molecular and Cellular Pharmacology, University of Miami Leonard M. Miller School of Medicine Miami, FL, USA
| | - Danuta Szczesna-Cordary
- Department of Molecular and Cellular Pharmacology, University of Miami Leonard M. Miller School of Medicine Miami, FL, USA
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Claes GRF, van Tienen FHJ, Lindsey P, Krapels IPC, Helderman-van den Enden ATJM, Hoos MB, Barrois YEG, Janssen JWH, Paulussen ADC, Sels JWEM, Kuijpers SHH, van Tintelen JP, van den Berg MP, Heesen WF, Garcia-Pavia P, Perrot A, Christiaans I, Salemink S, Marcelis CLM, Smeets HJM, Brunner HG, Volders PGA, van den Wijngaard A. Hypertrophic remodelling in cardiac regulatory myosin light chain (MYL2) founder mutation carriers. Eur Heart J 2015; 37:1815-22. [PMID: 26497160 DOI: 10.1093/eurheartj/ehv522] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Accepted: 09/16/2015] [Indexed: 01/25/2023] Open
Abstract
AIMS Phenotypic heterogeneity and incomplete penetrance are common in patients with hypertrophic cardiomyopathy (HCM). We aim to improve the understanding in genotype-phenotype correlations in HCM, particularly the contribution of an MYL2 founder mutation and risk factors to left ventricular hypertrophic remodelling. METHODS AND RESULTS We analysed 14 HCM families of whom 38 family members share the MYL2 c.64G > A [p.(Glu22Lys)] mutation and a common founder haplotype. In this unique cohort, we investigated factors influencing phenotypic outcome in addition to the primary mutation. The mutation alone showed benign disease manifestation with low penetrance. The co-presence of additional risk factors for hypertrophy such as hypertension, obesity, or other sarcomeric gene mutation increased disease penetrance substantially and caused HCM in 89% of MYL2 mutation carriers (P = 0.0005). The most prominent risk factor was hypertension, observed in 71% of mutation carriers with HCM and an additional risk factor. CONCLUSION The MYL2 mutation c.64G > A on its own is incapable of triggering clinical HCM in most carriers. However, the presence of an additional risk factor for hypertrophy, particularly hypertension, adds to the development of HCM. Early diagnosis of risk factors is important for early treatment of MYL2 mutation carriers and close monitoring should be guaranteed in this case. Our findings also suggest that the presence of hypertension or another risk factor for hypertrophy should not be an exclusion criterion for genetic studies.
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Affiliation(s)
- Godelieve R F Claes
- Department of Clinical Genetics, Unit Clinical Genomics, Maastricht University Medical Centre, P.O. Box 5800, 6229 GR Maastricht, The Netherlands School for Cardiovascular Diseases, Maastricht University Medical Centre, Maastricht, The Netherlands
| | - Florence H J van Tienen
- Department of Clinical Genetics, Unit Clinical Genomics, Maastricht University Medical Centre, P.O. Box 5800, 6229 GR Maastricht, The Netherlands School for Cardiovascular Diseases, Maastricht University Medical Centre, Maastricht, The Netherlands
| | - Patrick Lindsey
- Department of Clinical Genetics, Unit Clinical Genomics, Maastricht University Medical Centre, P.O. Box 5800, 6229 GR Maastricht, The Netherlands School for Cardiovascular Diseases, Maastricht University Medical Centre, Maastricht, The Netherlands
| | - Ingrid P C Krapels
- Department of Clinical Genetics, Unit Clinical Genomics, Maastricht University Medical Centre, P.O. Box 5800, 6229 GR Maastricht, The Netherlands School for Cardiovascular Diseases, Maastricht University Medical Centre, Maastricht, The Netherlands
| | - Apollonia T J M Helderman-van den Enden
- Department of Clinical Genetics, Unit Clinical Genomics, Maastricht University Medical Centre, P.O. Box 5800, 6229 GR Maastricht, The Netherlands School for Cardiovascular Diseases, Maastricht University Medical Centre, Maastricht, The Netherlands
| | - Marije B Hoos
- Department of Clinical Genetics, Unit Clinical Genomics, Maastricht University Medical Centre, P.O. Box 5800, 6229 GR Maastricht, The Netherlands School for Cardiovascular Diseases, Maastricht University Medical Centre, Maastricht, The Netherlands
| | - Yvette E G Barrois
- Department of Clinical Genetics, Unit Clinical Genomics, Maastricht University Medical Centre, P.O. Box 5800, 6229 GR Maastricht, The Netherlands School for Cardiovascular Diseases, Maastricht University Medical Centre, Maastricht, The Netherlands
| | - Johanna W H Janssen
- Department of Clinical Genetics, Unit Clinical Genomics, Maastricht University Medical Centre, P.O. Box 5800, 6229 GR Maastricht, The Netherlands
| | - Aimée D C Paulussen
- Department of Clinical Genetics, Unit Clinical Genomics, Maastricht University Medical Centre, P.O. Box 5800, 6229 GR Maastricht, The Netherlands School for Cardiovascular Diseases, Maastricht University Medical Centre, Maastricht, The Netherlands
| | - Jan-Willem E M Sels
- Department of Cardiology, Cardiovascular Research Institute Maastricht, Maastricht University Medical Centre, Maastricht, The Netherlands Department of Intensive Care, Maastricht University Medical Centre, Maastricht, The Netherlands
| | | | - J Peter van Tintelen
- Department of Clinical Genetics, Academic Medical Centre, Amsterdam, The Netherlands
| | - Maarten P van den Berg
- Department of Cardiology, University of Groningen, University Medical Centre Groningen, Groningen, The Netherlands
| | - Wilfred F Heesen
- Department of Cardiology, VieCuri Medical Centre, Venlo, The Netherlands
| | - Pablo Garcia-Pavia
- Heart Failure and Inherited Cardiac Diseases Unit, Department of Cardiology, Hospital Universitario Puerta de Hierro Majadahonda, Madrid, Spain
| | - Andreas Perrot
- Charité-Universitätsmedizin Berlin, Experimental & Clinical Research Centre, A Joint Cooperation Between the Charité Medical Faculty and the Max-Delbrück Centre for Molecular Medicine, Berlin, Germany
| | - Imke Christiaans
- Department of Clinical Genetics, Academic Medical Centre, Amsterdam, The Netherlands
| | - Simone Salemink
- Department of Human Genetics, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - Carlo L M Marcelis
- Department of Human Genetics, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - Hubert J M Smeets
- Department of Clinical Genetics, Unit Clinical Genomics, Maastricht University Medical Centre, P.O. Box 5800, 6229 GR Maastricht, The Netherlands
| | - Han G Brunner
- Department of Clinical Genetics, Unit Clinical Genomics, Maastricht University Medical Centre, P.O. Box 5800, 6229 GR Maastricht, The Netherlands Department of Human Genetics, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - Paul G A Volders
- Department of Cardiology, Cardiovascular Research Institute Maastricht, Maastricht University Medical Centre, Maastricht, The Netherlands
| | - Arthur van den Wijngaard
- Department of Clinical Genetics, Unit Clinical Genomics, Maastricht University Medical Centre, P.O. Box 5800, 6229 GR Maastricht, The Netherlands School for Cardiovascular Diseases, Maastricht University Medical Centre, Maastricht, The Netherlands
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11
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Santori M, Blanco-Verea A, Gil R, Cortis J, Becker K, Schneider PM, Carracedo A, Brion M. Broad-based molecular autopsy: a potential tool to investigate the involvement of subtle cardiac conditions in sudden unexpected death in infancy and early childhood. Arch Dis Child 2015; 100:952-6. [PMID: 26272908 DOI: 10.1136/archdischild-2015-308200] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/08/2015] [Accepted: 07/01/2015] [Indexed: 12/25/2022]
Abstract
OBJECTIVES Sudden unexplained death in children is a tragic and traumatic event, often worsened when the cause of death cannot be determined. This work aimed to investigate the presence of putative pathogenic genetic variants in a broad spectrum of cardiomyopathy, channelopathy and aortic disease associated genes that may have increased these children's vulnerability to sudden cardiac death. DESIGN We performed molecular autopsy of 41 cases of sudden unexplained death in infants and children through massive parallel sequencing of up to 86 sudden cardiac death-related genes. Multiple in silico analyses were conducted together with a thorough review of the literature in order to prioritise the putative pathogenic variants. RESULTS A total of 63 variants in 35 cases were validated. The largest proportion of these variants is located within cardiomyopathy genes although this would have been more expected of channelopathy gene variants. Subtle microscopic features of heart tissue may indicate the presence of an early onset cardiomyopathy as a predisposing condition to sudden unexpected death in some individuals. CONCLUSIONS Next-generation sequencing technologies reveal the existence of a wide spectrum of rare and novel genetic variants in sarcomere genes, compared with that of cardiac ion channels, in sudden unexplained death in infants and children. Our findings encourage further investigation of the role of early onset inherited cardiomyopathies and other diseases involving myocardial dysfunction in these deaths. Early detection of variants in these individuals could help to unmask subtle forms of disease within their relatives, who would eventually benefit from better counselling about their genetic history.
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Affiliation(s)
- Montserrat Santori
- Xenética de Enfermidades Cardiovasculares, Instituto de Investigación Sanitaria de Santiago, Red de Investigación Cardiovascular (RIC), Santiago De Compostela, Spain Grupo de Medicina Xenómica, University of Santiago de Compostela, Santiago de Compostela, Spain Fundación Pública Galega de Medicina Xenómica, SERGAS, Santiago de Compostela, Spain
| | - Alejandro Blanco-Verea
- Xenética de Enfermidades Cardiovasculares, Instituto de Investigación Sanitaria de Santiago, Red de Investigación Cardiovascular (RIC), Santiago De Compostela, Spain Grupo de Medicina Xenómica, University of Santiago de Compostela, Santiago de Compostela, Spain Fundación Pública Galega de Medicina Xenómica, SERGAS, Santiago de Compostela, Spain
| | - Rocio Gil
- Xenética de Enfermidades Cardiovasculares, Instituto de Investigación Sanitaria de Santiago, Red de Investigación Cardiovascular (RIC), Santiago De Compostela, Spain Grupo de Medicina Xenómica, University of Santiago de Compostela, Santiago de Compostela, Spain Fundación Pública Galega de Medicina Xenómica, SERGAS, Santiago de Compostela, Spain
| | - Judith Cortis
- Faculty of Medicine, Institute of Legal Medicine, University of Cologne, Cologne, Germany
| | - Katrin Becker
- Faculty of Medicine, Institute of Legal Medicine, University of Cologne, Cologne, Germany
| | - Peter M Schneider
- Faculty of Medicine, Institute of Legal Medicine, University of Cologne, Cologne, Germany
| | - Angel Carracedo
- Grupo de Medicina Xenómica, University of Santiago de Compostela, Santiago de Compostela, Spain Fundación Pública Galega de Medicina Xenómica, SERGAS, Santiago de Compostela, Spain Center of Excellence in Genomic Medicine Research, King Abdulaziz University Jeddah, Kingdom of Saudi Arabia
| | - Maria Brion
- Xenética de Enfermidades Cardiovasculares, Instituto de Investigación Sanitaria de Santiago, Red de Investigación Cardiovascular (RIC), Santiago De Compostela, Spain Grupo de Medicina Xenómica, University of Santiago de Compostela, Santiago de Compostela, Spain Fundación Pública Galega de Medicina Xenómica, SERGAS, Santiago de Compostela, Spain
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Functions of myosin light chain-2 (MYL2) in cardiac muscle and disease. Gene 2015; 569:14-20. [PMID: 26074085 DOI: 10.1016/j.gene.2015.06.027] [Citation(s) in RCA: 104] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2015] [Revised: 05/08/2015] [Accepted: 06/09/2015] [Indexed: 12/19/2022]
Abstract
Myosin light chain-2 (MYL2, also called MLC-2) is an ~19kDa sarcomeric protein that belongs to the EF-hand calcium binding protein superfamily and exists as three major isoforms encoded by three distinct genes in mammalian striated muscle. Each of the three different MLC-2 genes (MLC-2f; fast twitch skeletal isoform, MLC-2v; cardiac ventricular and slow twitch skeletal isoform, MLC-2a; cardiac atrial isoform) has a distinct developmental expression pattern in mammals. Genetic loss-of-function studies in mice demonstrated an essential role for cardiac isoforms of MLC-2, MLC-2v and MLC-2a, in cardiac contractile function during early embryogenesis. In the adult heart, MLC-2v function is regulated by phosphorylation, which displays a specific 1`expression pattern (high in epicardium and low in endocardium) across the heart. These data along with new data from computational models, genetic mouse models, and human studies have revealed a direct role for MLC-2v phosphorylation in cross-bridge cycling kinetics, calcium-dependent cardiac muscle contraction, cardiac torsion, cardiac function and various cardiac diseases. This review focuses on the regulatory functions of MLC-2 in the embryonic and adult heart, with an emphasis on phosphorylation-driven actions of MLC-2v in adult cardiac muscle, which provide new insights into mechanisms regulating myosin cycling kinetics and human cardiac diseases.
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