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Chia SPS, Pang JKS, Soh BS. Current RNA strategies in treating cardiovascular diseases. Mol Ther 2024; 32:580-608. [PMID: 38291757 PMCID: PMC10928165 DOI: 10.1016/j.ymthe.2024.01.028] [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: 09/14/2023] [Revised: 12/22/2023] [Accepted: 01/23/2024] [Indexed: 02/01/2024] Open
Abstract
Cardiovascular disease (CVD) continues to impose a significant global health burden, necessitating the exploration of innovative treatment strategies. Ribonucleic acid (RNA)-based therapeutics have emerged as a promising avenue to address the complex molecular mechanisms underlying CVD pathogenesis. We present a comprehensive review of the current state of RNA therapeutics in the context of CVD, focusing on the diverse modalities that bring about transient or permanent modifications by targeting the different stages of the molecular biology central dogma. Considering the immense potential of RNA therapeutics, we have identified common gene targets that could serve as potential interventions for prevalent Mendelian CVD caused by single gene mutations, as well as acquired CVDs developed over time due to various factors. These gene targets offer opportunities to develop RNA-based treatments tailored to specific genetic and molecular pathways, presenting a novel and precise approach to address the complex pathogenesis of both types of cardiovascular conditions. Additionally, we discuss the challenges and opportunities associated with delivery strategies to achieve targeted delivery of RNA therapeutics to the cardiovascular system. This review highlights the immense potential of RNA-based interventions as a novel and precise approach to combat CVD, paving the way for future advancements in cardiovascular therapeutics.
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Affiliation(s)
- Shirley Pei Shan Chia
- Institute of Molecular and Cell Biology (IMCB), Agency for Science, Technology and Research (A∗STAR), 61 Biopolis Drive, Proteos, Singapore 138673, Singapore; Department of Biological Sciences, National University of Singapore, 16 Science Drive 4, Singapore 117558, Singapore
| | - Jeremy Kah Sheng Pang
- Institute of Molecular and Cell Biology (IMCB), Agency for Science, Technology and Research (A∗STAR), 61 Biopolis Drive, Proteos, Singapore 138673, Singapore
| | - Boon-Seng Soh
- Institute of Molecular and Cell Biology (IMCB), Agency for Science, Technology and Research (A∗STAR), 61 Biopolis Drive, Proteos, Singapore 138673, Singapore; Department of Biological Sciences, National University of Singapore, 16 Science Drive 4, Singapore 117558, Singapore.
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2
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Genetic Insights into Primary Restrictive Cardiomyopathy. J Clin Med 2022; 11:jcm11082094. [PMID: 35456187 PMCID: PMC9027761 DOI: 10.3390/jcm11082094] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Revised: 04/05/2022] [Accepted: 04/06/2022] [Indexed: 12/04/2022] Open
Abstract
Restrictive cardiomyopathy is a rare cardiac disease causing severe diastolic dysfunction, ventricular stiffness and dilated atria. In consequence, it induces heart failure often with preserved ejection fraction and is associated with a high mortality. Since it is a poor clinical prognosis, patients with restrictive cardiomyopathy frequently require heart transplantation. Genetic as well as non-genetic factors contribute to restrictive cardiomyopathy and a significant portion of cases are of unknown etiology. However, the genetic forms of restrictive cardiomyopathy and the involved molecular pathomechanisms are only partially understood. In this review, we summarize the current knowledge about primary genetic restrictive cardiomyopathy and describe its genetic landscape, which might be of interest for geneticists as well as for cardiologists.
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3
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Suay-Corredera C, Alegre-Cebollada J. The mechanics of the heart: zooming in on hypertrophic cardiomyopathy and cMyBP-C. FEBS Lett 2022; 596:703-746. [PMID: 35224729 DOI: 10.1002/1873-3468.14301] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Revised: 01/10/2022] [Accepted: 01/14/2022] [Indexed: 11/10/2022]
Abstract
Hypertrophic cardiomyopathy (HCM), a disease characterized by cardiac muscle hypertrophy and hypercontractility, is the most frequently inherited disorder of the heart. HCM is mainly caused by variants in genes encoding proteins of the sarcomere, the basic contractile unit of cardiomyocytes. The most frequently mutated among them is MYBPC3, which encodes cardiac myosin-binding protein C (cMyBP-C), a key regulator of sarcomere contraction. In this review, we summarize clinical and genetic aspects of HCM and provide updated information on the function of the healthy and HCM sarcomere, as well as on emerging therapeutic options targeting sarcomere mechanical activity. Building on what is known about cMyBP-C activity, we examine different pathogenicity drivers by which MYBPC3 variants can cause disease, focussing on protein haploinsufficiency as a common pathomechanism also in nontruncating variants. Finally, we discuss recent evidence correlating altered cMyBP-C mechanical properties with HCM development.
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4
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Wang H, Lin Y, Zhang R, Chen Y, Ji W, Li S, Wang L, Tan R, Yuan J. Programmed Exercise Attenuates Familial Hypertrophic Cardiomyopathy in Transgenic E22K Mice via Inhibition of PKC-α/NFAT Pathway. Front Cardiovasc Med 2022; 9:808163. [PMID: 35265680 PMCID: PMC8899095 DOI: 10.3389/fcvm.2022.808163] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Accepted: 01/24/2022] [Indexed: 12/12/2022] Open
Abstract
Familial hypertrophic cardiomyopathy (FHCM), an autosomal dominant disease, is caused by mutations in genes encoding cardiac sarcomeric proteins. E22K, a mutation in the myosin regulatory light chain sarcomere gene, is associated with the development of FHCM. However, the molecular mechanisms by which E22K mutation promotes septal hypertrophy are still elusive. The hypertrophic markers, including beta-myosin heavy chain, atrial natriuretic peptide and B-type natriuretic peptide, were upregulated, as detected by fluorescence quantitative PCR. The gene expression profiles were greatly altered in the left ventricle of E22K mutant mice. Among these genes, nuclear factor of activated T cells (NFAT) and protein kinase C-alpha (PKC-α) were upregulated, and their protein expression levels were also verified to be elevated. The fibrosis markers, such as phosphorylated Smad and transforming growth factor beta receptor, were also elevated in transgenic E22K mice. After receiving 6 weeks of procedural exercise training, the expression levels of PKC-α and NFAT were reversed in E22K mouse hearts. In addition, the expression levels of several fibrosis-related genes such as transforming growth factor beta receptor 1, Smad4, and alpha smooth muscle actin in E22K mouse hearts were also reversed. Genes that associated with cardiac remodeling such as myocyte enhancer factor 2C, extracellular matrix protein 2 and fibroblast growth factor 12 were reduced after exercising. Taken together, our results indicate that exercise can improve hypertrophy and fibrosis-related indices in transgenic E22K mice via PKC-α/NFAT pathway, which provide new insight into the prevention and treatment of familial hypertrophic cardiomyopathy.
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Affiliation(s)
- Haiying Wang
- Department of Physiology, Institute of Basic Medical College, Jining Medical University, Jining, China
| | - Yuedong Lin
- Cardiac Emergency Department, Affiliated Hospital of Jining Medical University, Jining, China
| | - Ran Zhang
- Institute of Basic Medical College, Jining Medical University, Jining, China
| | - Yafen Chen
- Institute of Basic Medical College, Jining Medical University, Jining, China
| | - Wei Ji
- Institute of Basic Medical College, Jining Medical University, Jining, China
| | - Shenwei Li
- Institute of Basic Medical College, Jining Medical University, Jining, China
| | - Li Wang
- School of Nursing, Medical College, Soochow University, Suzhou, China
- *Correspondence: Li Wang
| | - Rubin Tan
- Department of Physiology, Basic Medical School, Xuzhou Medical University, Xuzhou, China
- Rubin Tan
| | - Jinxiang Yuan
- The Collaborative Innovation Center, Jining Medical University, Jining, China
- Jinxiang Yuan
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5
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Proteomic analysis reveals rattlesnake venom modulation of proteins associated with cardiac tissue damage in mouse hearts. J Proteomics 2022; 258:104530. [PMID: 35182786 PMCID: PMC9308947 DOI: 10.1016/j.jprot.2022.104530] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 01/19/2022] [Accepted: 02/13/2022] [Indexed: 11/20/2022]
Abstract
Snake envenomation is a common but neglected disease that affects millions of people around the world annually. Among venomous snake species in Brazil, the tropical rattlesnake (Crotalus durissus terrificus) accounts for the highest number of fatal envenomations and is responsible for the second highest number of bites. Snake venoms are complex secretions which, upon injection, trigger diverse physiological effects that can cause significant injury or death. The components of C. d. terrificus venom exhibit neurotoxic, myotoxic, hemotoxic, nephrotoxic, and cardiotoxic properties which present clinically as alteration of central nervous system function, motor paralysis, seizures, eyelid ptosis, ophthalmoplesia, blurred vision, coagulation disorders, rhabdomyolysis, myoglobinuria, and cardiorespiratory arrest. In this study, we focused on proteomic characterization of the cardiotoxic effects of C. d. terrificus venom in mouse models. We injected venom at half the lethal dose (LD50) into the gastrocnemius muscle. Mouse hearts were removed at set time points after venom injection (1 h, 6 h, 12 h, or 24 h) and subjected to trypsin digestion prior to high-resolution mass spectrometry. We analyzed the proteomic profiles of >1300 proteins and observed that several proteins showed noteworthy changes in their quantitative profiles, likely reflecting the toxic activity of venom components. Among the affected proteins were several associated with cellular deregulation and tissue damage. Changes in heart protein abundance offer insights into how they may work synergistically upon envenomation. SIGNIFICANCE: Venom of the tropical rattlesnake (Crotalus durissus terririficus) is known to be neurotoxic, myotoxic, nephrotoxic and cardiotoxic. Although there are several studies describing the biochemical effects of this venom, no work has yet described its proteomic effects in the cardiac tissue of mice. In this work, we describe the changes in several mouse cardiac proteins upon venom treatment. Our data shed new light on the clinical outcome of the envenomation by C. d. terrificus, as well as candidate proteins that could be investigated in efforts to improve current treatment approaches or in the development of novel therapeutic interventions in order to reduce mortality and morbidity resulting from envenomation.
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6
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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: 7] [Impact Index Per Article: 3.5] [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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7
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Vriz O, AlSergani H, Elshaer AN, Shaik A, Mushtaq AH, Lioncino M, Alamro B, Monda E, Caiazza M, Mauro C, Bossone E, Al-Hassnan ZN, Albert-Brotons D, Limongelli G. A complex unit for a complex disease: the HCM-Family Unit. Monaldi Arch Chest Dis 2021; 92. [PMID: 34964577 DOI: 10.4081/monaldi.2021.2147] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2021] [Accepted: 11/30/2021] [Indexed: 11/23/2022] Open
Abstract
Hypertrophic cardiomyopathy (HCM) is a group of heterogeneous disorders that are most commonly passed on in a heritable manner. It is a relatively rare disease around the globe, but due to increased rates of consanguinity within the Kingdom of Saudi Arabia, we speculate a high incidence of undiagnosed cases. The aim of this paper is to elucidate a systematic approach in dealing with HCM patients and since HCM has variable presentation, we have summarized differentials for diagnosis and how different subtypes and genes can have an impact on the clinical picture, management and prognosis. Moreover, we propose a referral multi-disciplinary team HCM-Family Unit in Saudi Arabia and an integrated role in a network between King Faisal Hospital and Inherited and Rare Cardiovascular Disease Unit-Monaldi Hospital, Italy (among the 24 excellence centers of the European Reference Network (ERN) GUARD-Heart). Graphical Abstract.
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Affiliation(s)
- Olga Vriz
- Department of Cardiology, King Faisal Specialist Hospital and Research Center, Riyadh.
| | - Hani AlSergani
- Department of Cardiology, King Faisal Specialist Hospital and Research Center, Riyadh.
| | | | | | | | - Michele Lioncino
- Inherited and Rare Cardiovascular Disease Unit, Department of Translational Medical Sciences, University of Campania "Luigi Vanvitelli", AORN dei Colli, Monaldi Hospital, Naples.
| | - Bandar Alamro
- Department of Cardiology, King Faisal Specialist Hospital and Research Center, Riyadh.
| | - Emanuele Monda
- Inherited and Rare Cardiovascular Disease Unit, Department of Translational Medical Sciences, University of Campania "Luigi Vanvitelli", AORN dei Colli, Monaldi Hospital, Naples.
| | - Martina Caiazza
- Inherited and Rare Cardiovascular Disease Unit, Department of Translational Medical Sciences, University of Campania "Luigi Vanvitelli", AORN dei Colli, Monaldi Hospital, Naples.
| | - Ciro Mauro
- Department of Cardiology, Cardarelli Hospital, Naples.
| | | | - Zuhair N Al-Hassnan
- Cardiovascular Genetics Program and Department of Medical Genetics, King Faisal Specialist Hospital and Research Centre, Riyadh.
| | - Dimpna Albert-Brotons
- Department of Cardiology, King Faisal Specialist Hospital and Research Center, Riyadh.
| | - Giuseppe Limongelli
- Inherited and Rare Cardiovascular Disease Unit, Department of Translational Medical Sciences, University of Campania "Luigi Vanvitelli", AORN dei Colli, Monaldi Hospital, Naples.
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8
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Kim KH, Pereira NL. Genetics of Cardiomyopathy: Clinical and Mechanistic Implications for Heart Failure. Korean Circ J 2021; 51:797-836. [PMID: 34327881 PMCID: PMC8484993 DOI: 10.4070/kcj.2021.0154] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Accepted: 06/14/2021] [Indexed: 11/11/2022] Open
Abstract
Genetic cardiomyopathies are an important cause of sudden cardiac death across all age groups. Genetic testing in heart failure clinics is useful for family screening and providing individual prognostic insight. Obtaining a family history of at least three generations, including the creation of a pedigree, is recommended for all patients with primary cardiomyopathy. Additionally, when appropriate, consultation with a genetic counsellor can aid in the success of a genetic evaluation. Clinical screening should be performed on all first-degree relatives of patients with genetic cardiomyopathy. Genetics has played an important role in the understanding of different cardiomyopathies, and the field of heart failure (HF) genetics is progressing rapidly. Much research has also focused on distinguishing markers of risk in patients with cardiomyopathy using genetic testing. While these efforts currently remain incomplete, new genomic technologies and analytical strategies provide promising opportunities to further explore the genetic architecture of cardiomyopathies, afford insight into the early manifestations of cardiomyopathy, and help define the molecular pathophysiological basis for cardiac remodeling. Cardiovascular physicians should be fully aware of the utility and potential pitfalls of incorporating genetic test results into pre-emptive treatment strategies for patients in the preliminary stages of HF. Future work will need to be directed towards elucidating the biological mechanisms of both rare and common gene variants and environmental determinants of plasticity in the genotype-phenotype relationship. This future research should aim to further our ability to identify, diagnose, and treat disorders that cause HF and sudden cardiac death in young patients, as well as prioritize improving our ability to stratify the risk for these patients prior to the onset of the more severe consequences of their disease.
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Affiliation(s)
- Kyung Hee Kim
- Division of Cardiology, Incheon Sejong General Hospital, Incheon, Korea.
| | - Naveen L Pereira
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN, USA.,Department of Clinical Genomics, Mayo Clinic, Rochester, MN, USA
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9
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Integrated transcriptomics and epigenomics reveal chamber-specific and species-specific characteristics of human and mouse hearts. PLoS Biol 2021; 19:e3001229. [PMID: 34003819 PMCID: PMC8130971 DOI: 10.1371/journal.pbio.3001229] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Accepted: 04/12/2021] [Indexed: 12/02/2022] Open
Abstract
DNA methylation, chromatin accessibility, and gene expression represent different levels information in biological process, but a comprehensive multiomics analysis of the mammalian heart is lacking. Here, we applied nucleosome occupancy and methylome sequencing, which detected DNA methylation and chromatin accessibility simultaneously, as well as RNA-seq, for multiomics analysis of the 4 chambers of adult and fetal human hearts, and adult mouse hearts. Our results showed conserved region-specific patterns in the mammalian heart at transcriptome and DNA methylation level. Adult and fetal human hearts showed distinct features in DNA methylome, chromatin accessibility, and transcriptome. Novel long noncoding RNAs were identified in the human heart, and the gene expression profiles of major cardiovascular diseases associated genes were displayed. Furthermore, cross-species comparisons revealed human-specific and mouse-specific differentially expressed genes between the atria and ventricles. We also reported the relationship among multiomics and found there was a bell-shaped relationship between gene-body methylation and expression in the human heart. In general, our study provided comprehensive spatiotemporal and evolutionary insights into the regulation of gene expression in the heart. Multi-omic analyses of the four chambers of the human and mouse heart, including transcriptome, DNA methylation and chromatin accessibility, reveals characteristic patterns of gene regulation at the level of heart regions.
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10
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Lee JTH, Patikas N, Kiselev VY, Hemberg M. Fast searches of large collections of single-cell data using scfind. Nat Methods 2021; 18:262-271. [PMID: 33649586 PMCID: PMC7116898 DOI: 10.1038/s41592-021-01076-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2019] [Accepted: 01/20/2021] [Indexed: 01/30/2023]
Abstract
Single-cell technologies have made it possible to profile millions of cells, but for these resources to be useful they must be easy to query and access. To facilitate interactive and intuitive access to single-cell data we have developed scfind, a single-cell analysis tool that facilitates fast search of biologically or clinically relevant marker genes in cell atlases. Using transcriptome data from six mouse cell atlases, we show how scfind can be used to evaluate marker genes, perform in silico gating, and identify both cell-type-specific and housekeeping genes. Moreover, we have developed a subquery optimization routine to ensure that long and complex queries return meaningful results. To make scfind more user friendly, we use indices of PubMed abstracts and techniques from natural language processing to allow for arbitrary queries. Finally, we show how scfind can be used for multi-omics analyses by combining single-cell ATAC-seq data with transcriptome data.
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Affiliation(s)
| | - Nikolaos Patikas
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, UK
- UK Dementia Research Institute, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
| | | | - Martin Hemberg
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, UK.
- Evergrande Center for Immunologic Disease, Harvard Medical School and Brigham and Women's Hospital, Boston, MA, USA.
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11
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Mazzarotto F, Olivotto I, Boschi B, Girolami F, Poggesi C, Barton PJR, Walsh R. Contemporary Insights Into the Genetics of Hypertrophic Cardiomyopathy: Toward a New Era in Clinical Testing? J Am Heart Assoc 2020; 9:e015473. [PMID: 32306808 PMCID: PMC7428545 DOI: 10.1161/jaha.119.015473] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Genetic testing for hypertrophic cardiomyopathy (HCM) is an established clinical technique, supported by 30 years of research into its genetic etiology. Although pathogenic variants are often detected in patients and used to identify at-risk relatives, the effectiveness of genetic testing has been hampered by ambiguous genetic associations (yielding uncertain and potentially false-positive results), difficulties in classifying variants, and uncertainty about genotype-negative patients. Recent case-control studies on rare variation, improved data sharing, and meta-analysis of case cohorts contributed to new insights into the genetic basis of HCM. In particular, although research into new genes and mechanisms remains essential, reassessment of Mendelian genetic associations in HCM argues that current clinical genetic testing should be limited to a small number of validated disease genes that yield informative and interpretable results. Accurate and consistent variant interpretation has benefited from new standardized variant interpretation guidelines and innovative approaches to improve classification. Most cases lacking a pathogenic variant are now believed to indicate non-Mendelian HCM, with more benign prognosis and minimal risk to relatives. Here, we discuss recent advances in the genetics of HCM and their application to clinical genetic testing together with practical issues regarding implementation. Although this review focuses on HCM, many of the issues discussed are also relevant to other inherited cardiac diseases.
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Affiliation(s)
- Francesco Mazzarotto
- Cardiomyopathy UnitCareggi University HospitalFlorenceItaly
- Cardiovascular Research CenterRoyal Brompton and Harefield NHS Foundation TrustLondonUnited Kingdom
- National Heart and Lung InstituteImperial College LondonUnited Kingdom
- Department of Clinical and Experimental MedicineUniversity of FlorenceItaly
| | - Iacopo Olivotto
- Cardiomyopathy UnitCareggi University HospitalFlorenceItaly
- Department of Clinical and Experimental MedicineUniversity of FlorenceItaly
| | - Beatrice Boschi
- Cardiomyopathy UnitCareggi University HospitalFlorenceItaly
- Genetic UnitCareggi University HospitalFlorenceItaly
| | - Francesca Girolami
- Cardiomyopathy UnitCareggi University HospitalFlorenceItaly
- Department of Paediatric CardiologyMeyer Children's HospitalFlorenceItaly
| | - Corrado Poggesi
- Department of Clinical and Experimental MedicineUniversity of FlorenceItaly
| | - Paul J. R. Barton
- Cardiovascular Research CenterRoyal Brompton and Harefield NHS Foundation TrustLondonUnited Kingdom
- National Heart and Lung InstituteImperial College LondonUnited Kingdom
| | - Roddy Walsh
- Department of Clinical and Experimental CardiologyHeart CenterAcademic Medical CenterAmsterdamthe Netherlands
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12
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Mazzarotto F, Olivotto I, Walsh R. Advantages and Perils of Clinical Whole-Exome and Whole-Genome Sequencing in Cardiomyopathy. Cardiovasc Drugs Ther 2020; 34:241-253. [DOI: 10.1007/s10557-020-06948-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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13
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Salfati EL, Spencer EG, Topol SE, Muse ED, Rueda M, Lucas JR, Wagner GN, Campman S, Topol EJ, Torkamani A. Re-analysis of whole-exome sequencing data uncovers novel diagnostic variants and improves molecular diagnostic yields for sudden death and idiopathic diseases. Genome Med 2019; 11:83. [PMID: 31847883 PMCID: PMC6916453 DOI: 10.1186/s13073-019-0702-2] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Accepted: 12/03/2019] [Indexed: 12/24/2022] Open
Abstract
Background Whole-exome sequencing (WES) has become an efficient diagnostic test for patients with likely monogenic conditions such as rare idiopathic diseases or sudden unexplained death. Yet, many cases remain undiagnosed. Here, we report the added diagnostic yield achieved for 101 WES cases re-analyzed 1 to 7 years after initial analysis. Methods Of the 101 WES cases, 51 were rare idiopathic disease cases and 50 were postmortem “molecular autopsy” cases of early sudden unexplained death. Variants considered for reporting were prioritized and classified into three groups: (1) diagnostic variants, pathogenic and likely pathogenic variants in genes known to cause the phenotype of interest; (2) possibly diagnostic variants, possibly pathogenic variants in genes known to cause the phenotype of interest or pathogenic variants in genes possibly causing the phenotype of interest; and (3) variants of uncertain diagnostic significance, potentially deleterious variants in genes possibly causing the phenotype of interest. Results Initial analysis revealed diagnostic variants in 13 rare disease cases (25.4%) and 5 sudden death cases (10%). Re-analysis resulted in the identification of additional diagnostic variants in 3 rare disease cases (5.9%) and 1 sudden unexplained death case (2%), which increased our molecular diagnostic yield to 31.4% and 12%, respectively. Conclusions The basis of new findings ranged from improvement in variant classification tools, updated genetic databases, and updated clinical phenotypes. Our findings highlight the potential for re-analysis to reveal diagnostic variants in cases that remain undiagnosed after initial WES.
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Affiliation(s)
- Elias L Salfati
- Scripps Research Translational Institute at Scripps Research, La Jolla, CA, USA
| | - Emily G Spencer
- Scripps Research Translational Institute at Scripps Research, La Jolla, CA, USA
| | - Sarah E Topol
- Scripps Research Translational Institute at Scripps Research, La Jolla, CA, USA
| | - Evan D Muse
- Scripps Research Translational Institute at Scripps Research, La Jolla, CA, USA.,Division of Cardiology, Scripps Clinic, La Jolla, CA, USA
| | - Manuel Rueda
- Scripps Research Translational Institute at Scripps Research, La Jolla, CA, USA
| | - Jonathan R Lucas
- Los Angeles County Department of Medical Examiner-Coroner, Los Angeles, CA, USA
| | - Glenn N Wagner
- San Diego County Medical Examiner's Office, San Diego, CA, USA
| | - Steven Campman
- San Diego County Medical Examiner's Office, San Diego, CA, USA
| | - Eric J Topol
- Scripps Research Translational Institute at Scripps Research, La Jolla, CA, USA.,Division of Cardiology, Scripps Clinic, La Jolla, CA, USA
| | - Ali Torkamani
- Scripps Research Translational Institute at Scripps Research, La Jolla, CA, USA.
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14
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Wang Z, Feng X, Li SC. SCDevDB: A Database for Insights Into Single-Cell Gene Expression Profiles During Human Developmental Processes. Front Genet 2019; 10:903. [PMID: 31611909 PMCID: PMC6775478 DOI: 10.3389/fgene.2019.00903] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2019] [Accepted: 08/26/2019] [Indexed: 11/19/2022] Open
Abstract
Single-cell RNA-seq studies profile thousands of cells in developmental processes. Current databases for human single-cell expression atlas only provide search and visualize functions for a selected gene in specific cell types or subpopulations. These databases are limited to technical properties or visualization of single-cell RNA-seq data without considering the biological relations of their collected cell groups. Here, we developed a database to investigate single-cell gene expression profiling during different developmental pathways (SCDevDB). In this database, we collected 10 human single-cell RNA-seq datasets, split these datasets into 176 developmental cell groups, and constructed 24 different developmental pathways. SCDevDB allows users to search the expression profiles of the interested genes across different developmental pathways. It also provides lists of differentially expressed genes during each developmental pathway, T-distributed stochastic neighbor embedding maps showing the relationships between developmental stages based on these differentially expressed genes, Gene Ontology, and Kyoto Encyclopedia of Genes and Genomes analysis results of these differentially expressed genes. This database is freely available at https://scdevdb.deepomics.org
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Affiliation(s)
- Zishuai Wang
- Department of Computer Science, City University of Hong Kong, Kowloon, Hong Kong
| | - Xikang Feng
- Department of Computer Science, City University of Hong Kong, Kowloon, Hong Kong
| | - Shuai Cheng Li
- Department of Computer Science, City University of Hong Kong, Kowloon, Hong Kong
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15
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Brodehl A, Ebbinghaus H, Deutsch MA, Gummert J, Gärtner A, Ratnavadivel S, Milting H. Human Induced Pluripotent Stem-Cell-Derived Cardiomyocytes as Models for Genetic Cardiomyopathies. Int J Mol Sci 2019; 20:ijms20184381. [PMID: 31489928 PMCID: PMC6770343 DOI: 10.3390/ijms20184381] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Revised: 08/29/2019] [Accepted: 09/03/2019] [Indexed: 12/17/2022] Open
Abstract
In the last few decades, many pathogenic or likely pathogenic genetic mutations in over hundred different genes have been described for non-ischemic, genetic cardiomyopathies. However, the functional knowledge about most of these mutations is still limited because the generation of adequate animal models is time-consuming and challenging. Therefore, human induced pluripotent stem cells (iPSCs) carrying specific cardiomyopathy-associated mutations are a promising alternative. Since the original discovery that pluripotency can be artificially induced by the expression of different transcription factors, various patient-specific-induced pluripotent stem cell lines have been generated to model non-ischemic, genetic cardiomyopathies in vitro. In this review, we describe the genetic landscape of non-ischemic, genetic cardiomyopathies and give an overview about different human iPSC lines, which have been developed for the disease modeling of inherited cardiomyopathies. We summarize different methods and protocols for the general differentiation of human iPSCs into cardiomyocytes. In addition, we describe methods and technologies to investigate functionally human iPSC-derived cardiomyocytes. Furthermore, we summarize novel genome editing approaches for the genetic manipulation of human iPSCs. This review provides an overview about the genetic landscape of inherited cardiomyopathies with a focus on iPSC technology, which might be of interest for clinicians and basic scientists interested in genetic cardiomyopathies.
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Affiliation(s)
- Andreas Brodehl
- Erich and Hanna Klessmann Institute, Heart and Diabetes Center NRW, University Hospital of the Ruhr-University Bochum, Georgstrasse 11, D-32545 Bad Oeynhausen, Germany.
| | - Hans Ebbinghaus
- Erich and Hanna Klessmann Institute, Heart and Diabetes Center NRW, University Hospital of the Ruhr-University Bochum, Georgstrasse 11, D-32545 Bad Oeynhausen, Germany.
| | - Marcus-André Deutsch
- Department of Thoracic and Cardiovascular Surgery, Heart and Diabetes Center NRW, University Hospital Ruhr-University Bochum, Georgstrasse 11, D-32545 Bad Oeynhausen, Germany.
| | - Jan Gummert
- Erich and Hanna Klessmann Institute, Heart and Diabetes Center NRW, University Hospital of the Ruhr-University Bochum, Georgstrasse 11, D-32545 Bad Oeynhausen, Germany.
- Department of Thoracic and Cardiovascular Surgery, Heart and Diabetes Center NRW, University Hospital Ruhr-University Bochum, Georgstrasse 11, D-32545 Bad Oeynhausen, Germany.
| | - Anna Gärtner
- Erich and Hanna Klessmann Institute, Heart and Diabetes Center NRW, University Hospital of the Ruhr-University Bochum, Georgstrasse 11, D-32545 Bad Oeynhausen, Germany.
| | - Sandra Ratnavadivel
- Erich and Hanna Klessmann Institute, Heart and Diabetes Center NRW, University Hospital of the Ruhr-University Bochum, Georgstrasse 11, D-32545 Bad Oeynhausen, Germany.
| | - Hendrik Milting
- Erich and Hanna Klessmann Institute, Heart and Diabetes Center NRW, University Hospital of the Ruhr-University Bochum, Georgstrasse 11, D-32545 Bad Oeynhausen, Germany.
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16
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Tran Vu MT, Nguyen TV, Huynh NV, Nguyen Thai HT, Pham Nguyen V, Ho Huynh TD. Presence of Hypertrophic Cardiomyopathy Related Gene Mutations and Clinical Manifestations in Vietnamese Patients With Hypertrophic Cardiomyopathy. Circ J 2019; 83:1908-1916. [PMID: 31308319 DOI: 10.1253/circj.cj-19-0190] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
BACKGROUND Hypertrophic cardiomyopathy (HCM) is associated primarily with pathogenic mutations in sarcomeric genes. The aim of this study was to identify the prevalence and distribution of disease-causing mutations in HCM-associated genes and the genotype-phenotype relationship in Vietnamese patients with HCM.Methods and Results:Genetic testing was performed by next-generation sequencing in 104 unrelated probands for 23 HCM-related genes and in 57 family members for the mutation(s) detected. Clinical manifestations were recorded for genotype-phenotype correlation analysis. Mutation detection rate was 43.4%. Mutations inMYBPC3accounted for 38.6%, followed byTPM1(20.5%),MYH7(18.2%),TNNT2(9.1%),TNNI3(4.5%) andMYL2(2.3%). A mutation inGLAassociated with Fabry disease was found in 1 patient. A mutation inTPM1(c.842T>C, p.Met281Thr) was identified in 8 unrelated probands (18.2%) and 8 family members from 5 probands. Genotype-positive status related toMYH7,TPM1, andTNNT2mutations was associated with severe clinical manifestations.MYH7-positive patients displayed worse prognosis compared withMYBPC3-positive patients. Interestingly,TPM1c.842T>C mutation was associated with high penetrance and severe HCM phenotype. CONCLUSIONS We report for the first time the prevalence of HCM-related gene variants in Vietnamese patients with HCM.MYH7,TPM1, andTNNT2mutations were associated with unfavorable prognosis.
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Affiliation(s)
| | - Thuy Vy Nguyen
- Research Center for Genetics and Reproductive Health, School of Medicine, Viet Nam National University.,Department of Genetics, Faculty of Biology and Biotechnology, University of Science, VNUHCM
| | | | - Hoang Tam Nguyen Thai
- Department of Genetics, Faculty of Biology and Biotechnology, University of Science, VNUHCM
| | | | - Thuy Duong Ho Huynh
- Research Center for Genetics and Reproductive Health, School of Medicine, Viet Nam National University.,Department of Genetics, Faculty of Biology and Biotechnology, University of Science, VNUHCM.,KTEST Science Company
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17
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Genomic approaches to identify hybrids and estimate admixture times in European wildcat populations. Sci Rep 2019; 9:11612. [PMID: 31406125 PMCID: PMC6691104 DOI: 10.1038/s41598-019-48002-w] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2018] [Accepted: 07/25/2019] [Indexed: 12/22/2022] Open
Abstract
The survival of indigenous European wildcat (Felis silvestris silvestris) populations can be locally threatened by introgressive hybridization with free-ranging domestic cats. Identifying pure wildcats and investigating the ancestry of admixed individuals becomes thus a conservation priority. We analyzed 63k cat Single Nucleotide Polymorphisms (SNPs) with multivariate, Bayesian and gene-search tools to better evaluate admixture levels between domestic and wild cats collected in Europe, timing and ancestry proportions of their hybrids and backcrosses, and track the origin (wild or domestic) of the genomic blocks carried by admixed cats, also looking for possible deviations from neutrality in their inheritance patterns. Small domestic ancestry blocks were detected in the genomes of most admixed cats, which likely originated from hybridization events occurring from 6 to 22 generations in the past. We identified about 1,900 outlier coding genes with excess of wild or domestic ancestry compared to random expectations in the admixed individuals. More than 600 outlier genes were significantly enriched for Gene Ontology (GO) categories mainly related to social behavior, functional and metabolic adaptive processes (wild-like genes), involved in cognition and neural crest development (domestic-like genes), or associated with immune system functions and lipid metabolism (parental-like genes). These kinds of genomic ancestry analyses could be reliably applied to unravel the admixture dynamics in European wildcats, as well as in other hybridizing populations, in order to design more efficient conservation plans.
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18
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Sitbon YH, Yadav S, Kazmierczak K, Szczesna-Cordary D. Insights into myosin regulatory and essential light chains: a focus on their roles in cardiac and skeletal muscle function, development and disease. J Muscle Res Cell Motil 2019; 41:313-327. [PMID: 31131433 DOI: 10.1007/s10974-019-09517-x] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Accepted: 05/21/2019] [Indexed: 12/15/2022]
Abstract
The activity of cardiac and skeletal muscles depends upon the ATP-coupled actin-myosin interactions to execute the power stroke and muscle contraction. The goal of this review article is to provide insight into the function of myosin II, the molecular motor of the heart and skeletal muscles, with a special focus on the role of myosin II light chain (MLC) components. Specifically, we focus on the involvement of myosin regulatory (RLC) and essential (ELC) light chains in striated muscle development, isoform appearance and their function in normal and diseased muscle. We review the consequences of isoform switching and knockout of specific MLC isoforms on cardiac and skeletal muscle function in various animal models. Finally, we discuss how dysregulation of specific RLC/ELC isoforms can lead to cardiac and skeletal muscle diseases and summarize the effects of most studied mutations leading to cardiac or skeletal myopathies.
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Affiliation(s)
- Yoel H Sitbon
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, 1600 NW 10th Ave, Miami, FL, 33136, USA
| | - Sunil Yadav
- 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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19
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The co-segregation of the MYL2 R58Q mutation in Chinese hypertrophic cardiomyopathy family and its pathological effect on cardiomyopathy disarray. Mol Genet Genomics 2019; 294:1241-1249. [PMID: 31104103 DOI: 10.1007/s00438-019-01578-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Accepted: 05/08/2019] [Indexed: 01/19/2023]
Abstract
Hypertrophic cardiomyopathy (HCM), a major cause of sudden death in youth, is largely affected by genetic factors. The R58Q mutation in the MYL2 gene was identified in some HCM patients and was considered as a deleterious HCM mutation. However, the passing of R58Q between generations along with HCM symptoms was observed only in small families with only two or three members; thus, whether R58Q is as deleterious as previously claimed remains questionable. Here, we reported a large four-generation Chinese family, and found that R58Q existed in all six members with HCM and two healthy juveniles who had not yet developed HCM yet, and presumably in three deceased members who suffered from sudden death. In addition, we also found that compared with other mutations, R58Q had a more severe effect on the cellular level. Therefore, we confirmed that R58Q could be passed from generation to generation along with HCM symptoms and that it was indeed a deleterious mutation for HCM. However, further study is needed to identify additional factors that may determine the various symptoms shown in different family members within the same family.
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20
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Kazmierczak K, Liang J, Yuan CC, Yadav S, Sitbon YH, Walz K, Ma W, Irving TC, Cheah JX, Gomes AV, Szczesna-Cordary D. Slow-twitch skeletal muscle defects accompany cardiac dysfunction in transgenic mice with a mutation in the myosin regulatory light chain. FASEB J 2019; 33:3152-3166. [PMID: 30365366 PMCID: PMC6404564 DOI: 10.1096/fj.201801402r] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2018] [Accepted: 10/01/2018] [Indexed: 01/06/2023]
Abstract
Myosin light chain 2 ( MYL2) gene encodes the myosin regulatory light chain (RLC) simultaneously in heart ventricles and in slow-twitch skeletal muscle. Using transgenic mice with cardiac-specific expression of the human R58Q-RLC mutant, we sought to determine whether the hypertrophic cardiomyopathy phenotype observed in papillary muscles (PMs) of R58Q mice is also manifested in slow-twitch soleus (SOL) muscles. Skinned SOL muscles and ventricular PMs of R58Q animals exhibited lower contractile force that was not observed in the fast-twitch extensor digitorum longus muscles of R58Q vs. wild-type-RLC mice, but mutant animals did not display gross muscle weakness in vivo. Consistent with SOL muscle abnormalities in R58Q vs. wild-type mice, myosin ATPase staining revealed a decreased proportion of fiber type I/type II only in SOL muscles but not in the extensor digitorum longus muscles. The similarities between SOL muscles and PMs of R58Q mice were further supported by quantitative proteomics. Differential regulation of proteins involved in energy metabolism, cell-cell interactions, and protein-protein signaling was concurrently observed in the hearts and SOL muscles of R58Q mice. In summary, even though R58Q expression was restricted to the heart of mice, functional similarities were clearly observed between the hearts and slow-twitch skeletal muscle, suggesting that MYL2 mutated models of hypertrophic cardiomyopathy may be useful research tools to study the molecular, structural, and energetic mechanisms of cardioskeletal myopathy associated with myosin RLC.-Kazmierczak, K., Liang, J., Yuan, C.-C., Yadav, S., Sitbon, Y. H., Walz, K., Ma, W., Irving, T. C., Cheah, J. X., Gomes, A. V., Szczesna-Cordary, D. Slow-twitch skeletal muscle defects accompany cardiac dysfunction in transgenic mice with a mutation in the myosin regulatory light chain.
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Affiliation(s)
- Katarzyna Kazmierczak
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Jingsheng Liang
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Chen-Ching Yuan
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Sunil Yadav
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Yoel H. Sitbon
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Katherina Walz
- Dr. John T. Macdonald Foundation Department of Human Genetics, John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Weikang Ma
- Department of Biological Sciences, Illinois Institute of Technology, Chicago, Illinois, USA
| | - Thomas C. Irving
- Department of Biological Sciences, Illinois Institute of Technology, Chicago, Illinois, USA
| | - Jenice X. Cheah
- Department of Neurobiology, Physiology, and Behavior, University of California, Davis, Davis, California, USA
| | - Aldrin V. Gomes
- Department of Neurobiology, Physiology, and Behavior, University of California, Davis, Davis, California, USA
| | - Danuta Szczesna-Cordary
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida, USA
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21
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Zhou W, Bos JM, Ye D, Tester DJ, Hrstka S, Maleszewski JJ, Ommen SR, Nishimura RA, Schaff HV, Kim CS, Ackerman MJ. Induced Pluripotent Stem Cell–Derived Cardiomyocytes from a Patient with MYL2-R58Q-Mediated Apical Hypertrophic Cardiomyopathy Show Hypertrophy, Myofibrillar Disarray, and Calcium Perturbations. J Cardiovasc Transl Res 2019; 12:394-403. [DOI: 10.1007/s12265-019-09873-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2018] [Accepted: 02/13/2019] [Indexed: 12/31/2022]
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22
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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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23
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Yadav S, Kazmierczak K, Liang J, Sitbon YH, Szczesna-Cordary D. Phosphomimetic-mediated in vitro rescue of hypertrophic cardiomyopathy linked to R58Q mutation in myosin regulatory light chain. FEBS J 2018; 286:151-168. [PMID: 30430732 DOI: 10.1111/febs.14702] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Revised: 10/03/2018] [Accepted: 11/13/2018] [Indexed: 12/16/2022]
Abstract
Myosin regulatory light chain (RLC) phosphorylation is important for cardiac muscle mechanics/function as well as for the Ca2+ -troponin/tropomyosin regulation of muscle contraction. This study focuses on the arginine to glutamine (R58Q) substitution in the human ventricular RLC (MYL2 gene), linked to malignant hypertrophic cardiomyopathy in humans and causing severe functional abnormalities in transgenic (Tg) R58Q mice, including inhibition of cardiac RLC phosphorylation. Using a phosphomimic recombinant RLC variant where Ser-15 at the phosphorylation site was substituted with aspartic acid (S15D) and placed in the background of R58Q, we aimed to assess whether we could rescue/mitigate R58Q-induced structural/functional abnormalities in vitro. We show rescue of several R58Q-exerted adverse phenotypes in S15D-R58Q-reconstituted porcine cardiac muscle preparations. A low level of maximal isometric force observed for R58Q- versus WT-reconstituted fibers was restored by S15D-R58Q. Significant beneficial effects were also observed on the Vmax of actin-activated myosin ATPase activity in S15D-R58Q versus R58Q-reconstituted myosin, along with its binding to fluorescently labeled actin. We also report that R58Q promotes the OFF state of myosin, both in reconstituted porcine fibers and in Tg mouse papillary muscles, thereby stabilizing the super-relaxed state (SRX) of myosin, characterized by a very low ATP turnover rate. Experiments in S15D-R58Q-reconstituted porcine fibers showed a mild destabilization of the SRX state, suggesting an S15D-mediated shift in disordered-relaxed (DRX)↔SRX equilibrium toward the DRX state of myosin. Our study shows that S15D-phosphomimic can be used as a potential rescue strategy to abrogate/alleviate the RLC mutation-induced phenotypes and is a likely candidate for therapeutic intervention in HCM patients.
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Affiliation(s)
- Sunil Yadav
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, FL, USA
| | - Katarzyna Kazmierczak
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, FL, USA
| | - Jingsheng Liang
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, FL, USA
| | - Yoel H Sitbon
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, FL, USA
| | - Danuta Szczesna-Cordary
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, FL, USA
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24
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Kampourakis T, Ponnam S, Irving M. Hypertrophic cardiomyopathy mutation R58Q in the myosin regulatory light chain perturbs thick filament-based regulation in cardiac muscle. J Mol Cell Cardiol 2018; 117:72-81. [PMID: 29452157 PMCID: PMC5883317 DOI: 10.1016/j.yjmcc.2018.02.009] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/20/2017] [Revised: 02/10/2018] [Accepted: 02/12/2018] [Indexed: 01/25/2023]
Abstract
Hypertrophic cardiomyopathy (HCM) is frequently linked to mutations in the protein components of the myosin-containing thick filaments leading to contractile dysfunction and ultimately heart failure. However, the molecular structure-function relationships that underlie these pathological effects remain largely obscure. Here we chose an example mutation (R58Q) in the myosin regulatory light chain (RLC) that is associated with a severe HCM phenotype and combined the results from a wide range of in vitro and in situ structural and functional studies on isolated protein components, myofibrils and ventricular trabeculae to create an extensive map of structure-function relationships. The results can be understood in terms of a unifying hypothesis that illuminates both the effects of the mutation and physiological signaling pathways. R58Q promotes an OFF state of the thick filaments that reduces the number of myosin head domains that are available for actin interaction and ATP utilization. Moreover this mutation uncouples two aspects of length-dependent activation (LDA), the cellular basis of the Frank-Starling relation that couples cardiac output to venous return; R58Q reduces maximum calcium-activated force with no significant effect on myofilament calcium sensitivity. Finally, phosphorylation of R58Q-RLC to levels that may be relevant both physiologically and pathologically restores the regulatory state of the thick filament and the effect of sarcomere length on maximum calcium-activated force and thick filament structure, as well as increasing calcium sensitivity. We conclude that perturbation of thick filament-based regulation may be a common mechanism in the etiology of missense mutation-associated HCM, and that this signaling pathway offers a promising target for the development of novel therapeutics. R58Q mutation in RLC (R58Q-RLC) promotes the myosin filament OFF state. R58Q-RLC reduces active force and perturbs length dependent activation (LDA). Phosphorylation of R58Q-RLC restores myosin filament regulation and LDA. Myosin filament regulation is a target for the development of heart failure drugs.
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Affiliation(s)
- Thomas Kampourakis
- Randall Centre for Cell and Molecular Biophysics, British Heart Foundation Centre of Research Excellence, King's College London, London SE1 1UL, United Kingdom.
| | - Saraswathi Ponnam
- Randall Centre for Cell and Molecular Biophysics, British Heart Foundation Centre of Research Excellence, King's College London, London SE1 1UL, United Kingdom
| | - Malcolm Irving
- Randall Centre for Cell and Molecular Biophysics, British Heart Foundation Centre of Research Excellence, King's College London, London SE1 1UL, United Kingdom
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25
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Simpson S, Rutland P, Rutland CS. Genomic Insights into Cardiomyopathies: A Comparative Cross-Species Review. Vet Sci 2017; 4:E19. [PMID: 29056678 PMCID: PMC5606618 DOI: 10.3390/vetsci4010019] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2016] [Revised: 03/15/2017] [Accepted: 03/15/2017] [Indexed: 12/19/2022] Open
Abstract
In the global human population, the leading cause of non-communicable death is cardiovascular disease. It is predicted that by 2030, deaths attributable to cardiovascular disease will have risen to over 20 million per year. This review compares the cardiomyopathies in both human and non-human animals and identifies the genetic associations for each disorder in each species/taxonomic group. Despite differences between species, advances in human medicine can be gained by utilising animal models of cardiac disease; likewise, gains can be made in animal medicine from human genomic insights. Advances could include undertaking regular clinical checks in individuals susceptible to cardiomyopathy, genetic testing prior to breeding, and careful administration of breeding programmes (in non-human animals), further development of treatment regimes, and drugs and diagnostic techniques.
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Affiliation(s)
- Siobhan Simpson
- Faculty of Medicine and Health Sciences, School of Veterinary Medicine and Science, The University of Nottingham, Sutton Bonington Campus, Loughborough LE12 5RD, UK.
| | - Paul Rutland
- Great Ormond Street Institute of Child Health, University College London, 30 Guilford Street, London WC1N 1EH, UK.
| | - Catrin Sian Rutland
- Faculty of Medicine and Health Sciences, School of Veterinary Medicine and Science, The University of Nottingham, Sutton Bonington Campus, Loughborough LE12 5RD, UK.
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26
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Pseudophosphorylation of cardiac myosin regulatory light chain: a promising new tool for treatment of cardiomyopathy. Biophys Rev 2017; 9:57-64. [PMID: 28510043 DOI: 10.1007/s12551-017-0248-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Accepted: 01/05/2017] [Indexed: 12/21/2022] Open
Abstract
Many genetic mutations in sarcomeric proteins, including the cardiac myosin regulatory light chain (RLC) encoded by the MYL2 gene, have been implicated in familial cardiomyopathies. Yet, the molecular mechanisms by which these mutant proteins regulate cardiac muscle mechanics in health and disease remain poorly understood. Evidence has been accumulating that RLC phosphorylation has an influential role in striated muscle contraction and, in addition to the conventional modulation via Ca2+ binding to troponin C, it can regulate cardiac muscle function. In this review, we focus on RLC mutations that have been reported to cause cardiomyopathy phenotypes via compromised RLC phosphorylation and elaborate on pseudo-phosphorylation rescue mechanisms. This new methodology has been discussed as an emerging exploratory tool to understand the role of phosphorylation as well as a genetic modality to prevent/rescue cardiomyopathy phenotypes. Finally, we summarize structural effects post-phosphorylation, a phenomenon that leads to an ordered shift in the myosin S1 and RLC conformational equilibrium between two distinct states.
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27
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Prognostic predictive value of gene mutations in Japanese patients with hypertrophic cardiomyopathy. Heart Vessels 2016; 32:700-707. [PMID: 27885498 DOI: 10.1007/s00380-016-0920-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Accepted: 11/11/2016] [Indexed: 01/08/2023]
Abstract
Although some studies have attempted to find useful prognostic factors in hypertrophic cardiomyopathy (HCM), those results are not fully helpful for use in actual clinical practice. Furthermore, several genetic abnormalities associated with HCM have been identified. However, the genotype-phenotype correlation in HCM remains to be elucidated. Here, we attempted to assess patients with different types of gene mutations causing HCM and investigate the prognosis. A total of 140 patients with HCM underwent a screening test for myofilament gene mutations by direct sequencing of eight sarcomeric genes. Patients with a single mutation in cardiac troponin T, cardiac troponin I, α-tropomyosin, and regulatory and essential light chains were excluded from the study because the number of cases was too small. The clinical presentations and outcomes of the remaining 127 patients with HCM, 31 β-myosin heavy chain (MYH7) mutation carriers, 19 cardiac myosin-binding protein C (MYBPC3) mutation carriers, and 77 mutation non-carriers were analyzed retrospectively. MYBPC3 mutation carriers had a high frequency of ventricular arrhythmia and syncope. Kaplan-Meier curves revealed no significant difference in prognosis among the three groups, but a lack of family history of sudden death (SD) and a past history of syncope were significantly related to poor prognosis. An absence of family history of SD and past history of syncope are useful prognostic factors in patients with HCM. MYH7 and MYBPC3 mutations did not significantly influence prognosis compared to non-carriers. However, patients with the MYBPC3 mutation should be closely followed for the possibility of SD.
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Huang W, Kazmierczak K, Zhou Z, Aguiar-Pulido V, Narasimhan G, Szczesna-Cordary D. Gene expression patterns in transgenic mouse models of hypertrophic cardiomyopathy caused by mutations in myosin regulatory light chain. Arch Biochem Biophys 2016; 601:121-32. [PMID: 26906074 PMCID: PMC5370580 DOI: 10.1016/j.abb.2016.02.022] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2015] [Revised: 02/15/2016] [Accepted: 02/18/2016] [Indexed: 12/23/2022]
Abstract
Using microarray and bioinformatics, we examined the gene expression profiles in transgenic mouse hearts expressing mutations in the myosin regulatory light chain shown to cause hypertrophic cardiomyopathy (HCM). We focused on two malignant RLC-mutations, Arginine 58→Glutamine (R58Q) and Aspartic Acid 166 → Valine (D166V), and one benign, Lysine 104 → Glutamic Acid (K104E)-mutation. Datasets of differentially expressed genes for each of three mutants were compared to those observed in wild-type (WT) hearts. The changes in the mutant vs. WT samples were shown as fold-change (FC), with stringency FC ≥ 2. Based on the gene profiles, we have identified the major signaling pathways that underlie the R58Q-, D166V- and K104E-HCM phenotypes. The correlations between different genotypes were also studied using network-based algorithms. Genes with strong correlations were clustered into one group and the central gene networks were identified for each HCM mutant. The overall gene expression patterns in all mutants were distinct from the WT profiles. Both malignant mutations shared certain classes of genes that were up or downregulated, but most similarities were noted between D166V and K104E mice, with R58Q hearts showing a distinct gene expression pattern. Our data suggest that all three HCM mice lead to cardiomyopathy in a mutation-specific manner and thus develop HCM through diverse mechanisms.
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Affiliation(s)
- Wenrui Huang
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL 33136, USA; Bioinformatics Research Group (BioRG), School of Computing and Information Sciences, Florida International University, Miami, FL 33199, USA
| | - Katarzyna Kazmierczak
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Zhiqun Zhou
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Vanessa Aguiar-Pulido
- Bioinformatics Research Group (BioRG), School of Computing and Information Sciences, Florida International University, Miami, FL 33199, USA
| | - Giri Narasimhan
- Bioinformatics Research Group (BioRG), School of Computing and Information Sciences, Florida International University, Miami, FL 33199, USA; Biomolecular Sciences Institute, Florida International University, Miami, FL 33199, USA
| | - Danuta Szczesna-Cordary
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL 33136, USA.
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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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Nagwekar J, Duggal D, Midde K, Rich R, Liang J, Kazmierczak K, Huang W, Fudala R, Gryczynski I, Gryczynski Z, Szczesna-Cordary D, Borejdo J. A Novel Method of Determining the Functional Effects of a Minor Genetic Modification of a Protein. Front Cardiovasc Med 2015; 2:35. [PMID: 26664906 PMCID: PMC4671333 DOI: 10.3389/fcvm.2015.00035] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Accepted: 10/30/2015] [Indexed: 11/17/2022] Open
Abstract
Contraction of muscles results from the ATP-coupled cyclic interactions of the myosin cross-bridges with actin filaments. Macroscopic parameters of contraction, such as maximum tension, speed of shortening, or ATPase activity, are unlikely to reveal differences between the wild-type and mutated (MUT) proteins when the level of transgenic protein expression is low. This is because macroscopic measurements are made on whole organs containing trillions of actin and myosin molecules. An average of the information collected from such a large assembly is bound to conceal any differences imposed by a small fraction of MUT molecules. To circumvent the averaging problem, the measurements were done on isolated ventricular myofibril (MF) in which thin filaments were sparsely labeled with a fluorescent dye. We isolated a single MF from a ventricle, oriented it vertically (to be able measure the orientation), and labeled 1 in 100,000 actin monomers with a fluorescent dye. We observed the fluorescence from a small confocal volume containing approximately three actin molecules. During the contraction of a ventricle actin constantly changes orientation (i.e., the transition moment of rigidly attached fluorophore fluctuates in time) because it is repetitively being "kicked" by myosin cross-bridges. An autocorrelation functions (ACFs) of these fluctuations are remarkably sensitive to the mutation of myosin. We examined the effects of Alanine to Threonine (A13T) mutation in the myosin regulatory light chain shown by population studies to cause hypertrophic cardiomyopathy. This is an appropriate example, because mutation is expressed at only 10% in the ventricles of transgenic mice. ACFs were either "Standard" (Std) (decaying monotonically in time) or "Non-standard" (NStd) (decaying irregularly). The sparse labeling of actin also allowed the measurement of the spatial distribution of actin molecules. Such distribution reflects the interaction of actin with myosin cross-bridges and is also remarkably sensitive to myosin mutation. The result showed that the A13T mutation caused 9% ACFs and 9% of spatial distributions of actin to be NStd, while the remaining 91% were Std, suggesting that the NStd performances were executed by the MUT myosin heads and that the Std performances were executed by non-MUT myosin heads. We conclude that the method explored in this study is a sensitive and valid test of the properties of low prevalence mutations in sarcomeric proteins.
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Affiliation(s)
- Janhavi Nagwekar
- Department of Cell Biology, Center for Commercialization of Fluorescence Technologies, University of North Texas Health Science Center, Fort Worth, TX, USA
| | - Divya Duggal
- Department of Cell Biology, Center for Commercialization of Fluorescence Technologies, University of North Texas Health Science Center, Fort Worth, TX, USA
| | - Krishna Midde
- Department of Cell Biology, Center for Commercialization of Fluorescence Technologies, University of North Texas Health Science Center, Fort Worth, TX, USA
| | - Ryan Rich
- Department of Mathematics, Computer Science, and Physics, Texas Wesleyan University, Fort Worth, TX, USA
| | - Jingsheng Liang
- Department of Molecular and Cellular Pharmacology, Miller School of Medicine, University of Miami, Miami, FL, USA
| | - Katarzyna Kazmierczak
- Department of Molecular and Cellular Pharmacology, Miller School of Medicine, University of Miami, Miami, FL, USA
| | - Wenrui Huang
- Department of Molecular and Cellular Pharmacology, Miller School of Medicine, University of Miami, Miami, FL, USA
| | - Rafal Fudala
- Department of Cell Biology, Center for Commercialization of Fluorescence Technologies, University of North Texas Health Science Center, Fort Worth, TX, USA
| | - Ignacy Gryczynski
- Department of Cell Biology, Center for Commercialization of Fluorescence Technologies, University of North Texas Health Science Center, Fort Worth, TX, USA
| | - Zygmunt Gryczynski
- Department of Physics and Astronomy, Texas Christian University, Fort Worth, TX, USA
| | - Danuta Szczesna-Cordary
- Department of Molecular and Cellular Pharmacology, Miller School of Medicine, University of Miami, Miami, FL, USA
| | - Julian Borejdo
- Department of Cell Biology, Center for Commercialization of Fluorescence Technologies, University of North Texas Health Science Center, Fort Worth, TX, USA
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Glotov AS, Kazakov SV, Zhukova EA, Alexandrov AV, Glotov OS, Pakin VS, Danilova MM, Poliakova IV, Niyazova SS, Chakova NN, Komissarova SM, Kurnikova EA, Sarana AM, Sherbak SG, Sergushichev AA, Shalyto AA, Baranov VS. Targeted next-generation sequencing (NGS) of nine candidate genes with custom AmpliSeq in patients and a cardiomyopathy risk group. Clin Chim Acta 2015; 446:132-40. [PMID: 25892673 DOI: 10.1016/j.cca.2015.04.014] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2014] [Revised: 03/23/2015] [Accepted: 04/08/2015] [Indexed: 12/11/2022]
Abstract
BACKGROUND Hypertrophic cardiomyopathy is a common genetic cardiac disease. Prevention and early diagnosis of this disease are very important. Because of the large number of causative genes and the high rate of mutations involved in the pathogenesis of this disease, traditional methods of early diagnosis are ineffective. METHODS We developed a custom AmpliSeq panel for NGS sequencing of the coding sequences of ACTC1, MYBPC3, MYH7, MYL2, MYL3, TNNI3, TNNT2, TPM1, and CASQ2. A genetic analysis of student cohorts (with and without cardiomyopathy risk in their medical histories) and patients with cardiomyopathies was performed. For the statistical and bioinformatics analysis, Polyphen2, SIFT, SnpSift and PLINK software were used. To select genetic markers in the patients with cardiomyopathy and in the students of the high risk group, four additive models were applied. RESULTS Our AmpliSeq custom panel allowed us to efficiently explore targeted sequences. Based on the score analysis, we detected three substitutions in the MYBPC3 and CASQ2 genes and six combinations between loci in the MYBPC3, MYH7 and CASQ2 genes that were responsible for cardiomyopathy risk in our cohorts. We also detected substitutions in the TNNT2 gene that can be considered as protective against cardiomyopathy. CONCLUSION We used NGS with AmpliSeq libraries and Ion PGM sequencing to develop improved predictive information for patients at risk of cardiomyopathy.
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Affiliation(s)
- Andrey S Glotov
- Department of Genetics and Biotechnology, Saint Petersburg State University, Universitetskaya nab., 7-9, St. Petersburg 199034, Russia; Laboratory of Prenatal Diagnostics of Hereditary Diseases, Federal State Budget Scientific Institution "The Research Institute of Obstetrics, Gynecology and Reproductology named after D.O.Ott", Mendeleyevskaya lin., 3, St. Petersburg 199034, Russia.
| | - Sergey V Kazakov
- Computer Technologies Laboratory, ITMO University, Kronverksky pr., 49, St. Petersburg 197101, Russia
| | - Elena A Zhukova
- Laboratory of Prenatal Diagnostics of Hereditary Diseases, Federal State Budget Scientific Institution "The Research Institute of Obstetrics, Gynecology and Reproductology named after D.O.Ott", Mendeleyevskaya lin., 3, St. Petersburg 199034, Russia
| | - Anton V Alexandrov
- Computer Technologies Laboratory, ITMO University, Kronverksky pr., 49, St. Petersburg 197101, Russia
| | - Oleg S Glotov
- Department of Genetics and Biotechnology, Saint Petersburg State University, Universitetskaya nab., 7-9, St. Petersburg 199034, Russia; Laboratory of Prenatal Diagnostics of Hereditary Diseases, Federal State Budget Scientific Institution "The Research Institute of Obstetrics, Gynecology and Reproductology named after D.O.Ott", Mendeleyevskaya lin., 3, St. Petersburg 199034, Russia
| | - Vladimir S Pakin
- Department of Genetics and Biotechnology, Saint Petersburg State University, Universitetskaya nab., 7-9, St. Petersburg 199034, Russia; Laboratory of Prenatal Diagnostics of Hereditary Diseases, Federal State Budget Scientific Institution "The Research Institute of Obstetrics, Gynecology and Reproductology named after D.O.Ott", Mendeleyevskaya lin., 3, St. Petersburg 199034, Russia
| | - Maria M Danilova
- Department of Genetics and Biotechnology, Saint Petersburg State University, Universitetskaya nab., 7-9, St. Petersburg 199034, Russia; Laboratory of Prenatal Diagnostics of Hereditary Diseases, Federal State Budget Scientific Institution "The Research Institute of Obstetrics, Gynecology and Reproductology named after D.O.Ott", Mendeleyevskaya lin., 3, St. Petersburg 199034, Russia
| | - Irina V Poliakova
- Department of Genetics and Biotechnology, Saint Petersburg State University, Universitetskaya nab., 7-9, St. Petersburg 199034, Russia; Laboratory of Prenatal Diagnostics of Hereditary Diseases, Federal State Budget Scientific Institution "The Research Institute of Obstetrics, Gynecology and Reproductology named after D.O.Ott", Mendeleyevskaya lin., 3, St. Petersburg 199034, Russia
| | - Svetlana S Niyazova
- Laboratory of Modelling of Genetic Processes, Institute of Genetics and Cytology, National Academy of Sciences, Akademicheskaya str., 27, Minsk 220072, Belarus
| | - Natalia N Chakova
- Laboratory of Modelling of Genetic Processes, Institute of Genetics and Cytology, National Academy of Sciences, Akademicheskaya str., 27, Minsk 220072, Belarus
| | - Svetlana M Komissarova
- Scientific and Practical center of Cardiology, Rozy Luxemburg str., 110, Minsk 220036, Belarus
| | - Elena A Kurnikova
- Department of Faculty Therapy on Behalf of Prof. VA Waldman, Saint Petersburg State Pediatric Medical University, Lithuanian str., 2, St. Petersburg 194100, Russia
| | - Andrey M Sarana
- City Hospital No. 40, Borisov str., 9, Sestroretsk, St. Petersburg 197706, Russia
| | - Sergey G Sherbak
- City Hospital No. 40, Borisov str., 9, Sestroretsk, St. Petersburg 197706, Russia
| | - Alexey A Sergushichev
- Computer Technologies Laboratory, ITMO University, Kronverksky pr., 49, St. Petersburg 197101, Russia
| | - Anatoly A Shalyto
- Computer Technologies Laboratory, ITMO University, Kronverksky pr., 49, St. Petersburg 197101, Russia
| | - Vladislav S Baranov
- Department of Genetics and Biotechnology, Saint Petersburg State University, Universitetskaya nab., 7-9, St. Petersburg 199034, Russia; Laboratory of Prenatal Diagnostics of Hereditary Diseases, Federal State Budget Scientific Institution "The Research Institute of Obstetrics, Gynecology and Reproductology named after D.O.Ott", Mendeleyevskaya lin., 3, St. Petersburg 199034, Russia
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Duggal D, Nagwekar J, Rich R, Huang W, Midde K, Fudala R, Das H, Gryczynski I, Szczesna-Cordary D, Borejdo J. Effect of a myosin regulatory light chain mutation K104E on actin-myosin interactions. Am J Physiol Heart Circ Physiol 2015; 308:H1248-57. [PMID: 25770245 DOI: 10.1152/ajpheart.00834.2014] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/26/2014] [Accepted: 03/03/2015] [Indexed: 11/22/2022]
Abstract
Familial hypertrophic cardiomyopathy (FHC) is the most common cause of sudden cardiac death in young individuals. Molecular mechanisms underlying this disorder are largely unknown; this study aims at revealing how disruptions in actin-myosin interactions can play a role in this disorder. Cross-bridge (XB) kinetics and the degree of order were examined in contracting myofibrils from the ex vivo left ventricles of transgenic (Tg) mice expressing FHC regulatory light chain (RLC) mutation K104E. Because the degree of order and the kinetics are best studied when an individual XB makes a significant contribution to the overall signal, the number of observed XBs in an ex vivo ventricle was minimized to ∼20. Autofluorescence and photobleaching were minimized by labeling the myosin lever arm with a relatively long-lived red-emitting dye containing a chromophore system encapsulated in a cyclic macromolecule. Mutated XBs were significantly better ordered during steady-state contraction and during rigor, but the mutation had no effect on the degree of order in relaxed myofibrils. The K104E mutation increased the rate of XB binding to thin filaments and the rate of execution of the power stroke. The stopped-flow experiments revealed a significantly faster observed dissociation rate in Tg-K104E vs. Tg-wild-type (WT) myosin and a smaller second-order ATP-binding rate for the K104E compared with WT myosin. Collectively, our data indicate that the mutation-induced changes in the interaction of myosin with actin during the contraction-relaxation cycle may contribute to altered contractility and the development of FHC.
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Affiliation(s)
- D Duggal
- Department of Cell Biology & Immunology and Center for Commercialization of Fluorescence Technologies, University of North Texas, Health Science Center, Fort Worth, Texas; and
| | - J Nagwekar
- Department of Cell Biology & Immunology and Center for Commercialization of Fluorescence Technologies, University of North Texas, Health Science Center, Fort Worth, Texas; and
| | - R Rich
- Department of Cell Biology & Immunology and Center for Commercialization of Fluorescence Technologies, University of North Texas, Health Science Center, Fort Worth, Texas; and
| | - W Huang
- Department of Molecular & Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida; and
| | - K Midde
- Department of Cell Biology & Immunology and Center for Commercialization of Fluorescence Technologies, University of North Texas, Health Science Center, Fort Worth, Texas; and
| | - R Fudala
- Department of Cell Biology & Immunology and Center for Commercialization of Fluorescence Technologies, University of North Texas, Health Science Center, Fort Worth, Texas; and
| | - H Das
- Department of Cell Biology & Immunology and Center for Commercialization of Fluorescence Technologies, University of North Texas, Health Science Center, Fort Worth, Texas; and Department of Pharmacology and Neuroscience, Institute of Aging and Alzheimer's Disease Research, Institute of Cancer Research, Fort Worth, Texas
| | - I Gryczynski
- Department of Cell Biology & Immunology and Center for Commercialization of Fluorescence Technologies, University of North Texas, Health Science Center, Fort Worth, Texas; and
| | - D Szczesna-Cordary
- Department of Molecular & Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida; and
| | - J Borejdo
- Department of Cell Biology & Immunology and Center for Commercialization of Fluorescence Technologies, University of North Texas, Health Science Center, Fort Worth, Texas; and
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Beraldi R, Li X, Martinez Fernandez A, Reyes S, Secreto F, Terzic A, Olson TM, Nelson TJ. Rbm20-deficient cardiogenesis reveals early disruption of RNA processing and sarcomere remodeling establishing a developmental etiology for dilated cardiomyopathy. Hum Mol Genet 2014; 23:3779-91. [PMID: 24584570 DOI: 10.1093/hmg/ddu091] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Dilated cardiomyopathy (DCM) due to mutations in RBM20, a gene encoding an RNA-binding protein, is associated with high familial penetrance, risk of progressive heart failure and sudden death. Although genetic investigations and physiological models have established the linkage of RBM20 with early-onset DCM, the underlying basis of cellular and molecular dysfunction is undetermined. Modeling human genetics using a high-throughput pluripotent stem cell platform was herein designed to pinpoint the initial transcriptome dysfunction and mechanistic corruption in disease pathogenesis. Tnnt2-pGreenZeo pluripotent stem cells were engineered to knockdown Rbm20 (shRbm20) to determine the cardiac-pathogenic phenotype during cardiac differentiation. Intracellular Ca(2+) transients revealed Rbm20-dependent alteration in Ca(2+) handling, coinciding with known pathological splice variants of Titin and Camk2d genes by Day 24 of cardiogenesis. Ultrastructural analysis demonstrated elongated and thinner sarcomeres in the absence of Rbm20 that is consistent with human cardiac biopsy samples. Furthermore, Rbm20-depleted transcriptional profiling at Day 12 identified Rbm20-dependent dysregulation with 76% of differentially expressed genes linked to known cardiac pathology ranging from primordial Nkx2.5 to mature cardiac Tnnt2 as the initial molecular aberrations. Notably, downstream consequences of Rbm20-depletion at Day 24 of differentiation demonstrated significant dysregulation of extracellular matrix components such as the anomalous overexpression of the Vtn gene. By using the pluripotent stem cell platform to model human cardiac disease according to a stage-specific cardiogenic roadmap, we established a new paradigm of familial DCM pathogenesis as a developmental disorder that is patterned during early cardiogenesis and propagated with cellular mechanisms of pathological cardiac remodeling.
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Affiliation(s)
| | - Xing Li
- Division of Biomedical Statistics and Informatics, Department of Health Sciences Research
| | | | | | | | - Andre Terzic
- Division of Cardiovascular Diseases, Center of Regenerative Medicine, Division of Pediatric Cardiology, Molecular Pharmacology and Experimental Therapeutics
| | - Timothy M Olson
- Division of Cardiovascular Diseases, Division of Pediatric Cardiology, Molecular Pharmacology and Experimental Therapeutics
| | - Timothy J Nelson
- Center of Regenerative Medicine, Molecular Pharmacology and Experimental Therapeutics, General Internal Medicine and Transplant Center, Mayo Clinic, Rochester, MN 55905, USA
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Charron P, Komajda M. Molecular genetics in hypertrophic cardiomyopathy: towards individualized management of the disease. Expert Rev Mol Diagn 2014; 6:65-78. [PMID: 16359268 DOI: 10.1586/14737159.6.1.65] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Hypertrophic cardiomyopathy is a relatively common genetic disease, affecting one person per 500 in the general population, and is clinically defined by the presence of unexplained left ventricular hypertrophy. Although recognized as the most common cause of sudden death in the young (especially in athletes), the cardiac expression of the disease is highly variable with respect to age at onset, degree of symptoms and risk of cardiac death. As a consequence, therapeutic strategies are diverse and must be adapted to the specific features of an individual. Recently, the molecular bases of the disease have been unraveled with the identification of a large number of mutations in genes encoding sarcomeric proteins. This review focuses on the impact of the molecular data on the understanding of the disease, and considers the emerging issues regarding the impact of molecular testing on the management of patients (or relatives) in clinical practice.
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Affiliation(s)
- Philippe Charron
- Centre of Reference for Cardiac Hereditary Diseases, Département de Génétique, Hôpital Pitié-Salpêtrière, 47 Boulevard de l'Hôpital, 75013 Paris, France.
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35
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Gong S, Ware JS, Walsh R, Cook SA. NECTAR: a database of codon-centric missense variant annotations. Nucleic Acids Res 2013; 42:D1013-9. [PMID: 24297257 PMCID: PMC3965063 DOI: 10.1093/nar/gkt1245] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
NECTAR (Non-synonymous Enriched Coding muTation ARchive; http://nectarmutation.org) is a database and web application to annotate disease-related and functionally important amino acids in human proteins. A number of tools are available to facilitate the interpretation of DNA variants identified in diagnostic or research sequencing. These typically identify previous reports of DNA variation at a given genomic location, predict its effects on transcript and protein sequence and may predict downstream functional consequences. Previous reports and functional annotations are typically linked by the genomic location of the variant observed. NECTAR collates disease-causing variants and functionally important amino acid residues from a number of sources. Importantly, rather than simply linking annotations by a shared genomic location, NECTAR annotates variants of interest with details of previously reported variation affecting the same codon. This provides a much richer data set for the interpretation of a novel DNA variant. NECTAR also identifies functionally equivalent amino acid residues in evolutionarily related proteins (paralogues) and, where appropriate, transfers annotations between them. As well as accessing these data through a web interface, users can upload batches of variants in variant call format (VCF) for annotation on-the-fly. The database is freely available to download from the ftp site: ftp://ftp.nectarmutation.org.
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Affiliation(s)
- Sungsam Gong
- NIHR Cardiovascular Biomedical Research Unit, Royal Brompton and Harefield NHS Foundation Trust and Imperial College London, London SW3 6NP, UK, National Heart and Lung Institute, Imperial College, London SW3 6LY, UK, National Heart Centre Singapore, Singapore 168752, Singapore and Cardiovascular & Metabolic Disorders, Duke National University of Singapore, Singapore 169857, Singapore
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Wang L, Muthu P, Szczesna-Cordary D, Kawai M. Diversity and similarity of motor function and cross-bridge kinetics in papillary muscles of transgenic mice carrying myosin regulatory light chain mutations D166V and R58Q. J Mol Cell Cardiol 2013; 62:153-63. [PMID: 23727233 PMCID: PMC3809071 DOI: 10.1016/j.yjmcc.2013.05.012] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/15/2013] [Revised: 05/16/2013] [Accepted: 05/19/2013] [Indexed: 10/26/2022]
Abstract
Mechanical properties of skinned papillary muscle fibers from transgenic mice expressing familial hypertrophic cardiomyopathy associated mutations D166V and R58Q in myosin regulatory light chain were investigated. Elementary steps and the apparent rate constants of the cross-bridge cycle were characterized from the tension transients induced by sinusoidal length changes during maximal Ca(2+) activation, together with ATP, ADP, and Pi studies. The tension-pCa relation was also tested in two sets of solutions with differing Pi and ionic strength. Our results showed that in both mutants the fast apparent rate constant 2πc and the rate constants of the cross-bridge detachment step (k2) were smaller than those of wild type (WT), demonstrating the slower cross-bridge kinetics. D166V showed significantly smaller ATP (K1) and ADP (K0) association constants than WT, displaying weaker ATP binding and easier ADP release, whereas those of R58Q were not significantly different from WT. In tension-pCa study, both D166V and R58Q mutations exhibited increased Ca(2+) sensitivity and less cooperativity. We conclude that, while the two FHC mutations have similar clinical manifestations and prognosis, some of the mechanical parameters of cross-bridges (K0, K1) are differently modified, whereas some others (Ca(2+)-sensitivity, cooperativity, k2) are similarly modified by these two FHC associated mutations.
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Affiliation(s)
- Li Wang
- Departments of Anatomy and Cell Biology, and Internal Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Priya Muthu
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Danuta Szczesna-Cordary
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Masataka Kawai
- Departments of Anatomy and Cell Biology, and Internal Medicine, University of Iowa, Iowa City, IA 52242, USA
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Weterman MAJ, Barth PG, van Spaendonck-Zwarts KY, Aronica E, Poll-The BT, Brouwer OF, van Tintelen JP, Qahar Z, Bradley EJ, de Wissel M, Salviati L, Angelini C, van den Heuvel L, Thomasse YEM, Backx AP, Nürnberg G, Nürnberg P, Baas F. Recessive MYL2 mutations cause infantile type I muscle fibre disease and cardiomyopathy. ACTA ACUST UNITED AC 2013; 136:282-93. [PMID: 23365102 DOI: 10.1093/brain/aws293] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
A cardioskeletal myopathy with onset and death in infancy, morphological features of muscle type I hypotrophy with myofibrillar disorganization and dilated cardiomyopathy was previously reported in three Dutch families. Here we report the genetic cause of this disorder. Multipoint parametric linkage analysis of six Dutch patients identified a homozygous region of 2.1 Mb on chromosome 12, which was shared between all Dutch patients, with a log of odds score of 10.82. Sequence analysis of the entire linkage region resulted in the identification of a homozygous mutation in the last acceptor splice site of the myosin regulatory light chain 2 gene (MYL2) as the genetic cause. MYL2 encodes a myosin regulatory light chain (MLC-2V). The myosin regulatory light chains bind, together with the essential light chains, to the flexible neck region of the myosin heavy chain in the hexameric myosin complex and have a structural and regulatory role in muscle contraction. The MYL2 mutation results in use of a cryptic splice site upstream of the last exon causing a frameshift and replacement of the last 32 codons by 20 different codons. Whole exome sequencing of an Italian patient with similar clinical features showed compound heterozygosity for two other mutations affecting the same exon of MYL2, also resulting in mutant proteins with altered C-terminal tails. As a consequence of these mutations, the second EF-hand domain is disrupted. EF-hands, assumed to function as calcium sensors, can undergo a conformational change upon binding of calcium that is critical for interactions with downstream targets. Immunohistochemical staining of skeletal muscle tissue of the Dutch patients showed a diffuse and weak expression of the mutant protein without clear fibre specificity, while normal protein was absent. Heterozygous missense mutations in MYL2 are known to cause dominant hypertrophic cardiomyopathy; however, none of the parents showed signs of cardiomyopathy. In conclusion, the mutations in the last exon of MYL2 are responsible for a novel autosomal recessive lethal myosinopathy due to defects changing the C-terminal tail of the ventricular form of the myosin regulatory light chain. We propose 'light chain myopathy' as a name for this MYL2-associated myopathy.
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Affiliation(s)
- Marian A J Weterman
- Department of Genome Analysis k2-213, Academic Medical Centre Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands.
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Muthu P, Kazmierczak K, Jones M, Szczesna-Cordary D. The effect of myosin RLC phosphorylation in normal and cardiomyopathic mouse hearts. J Cell Mol Med 2012; 16:911-9. [PMID: 21696541 PMCID: PMC3193868 DOI: 10.1111/j.1582-4934.2011.01371.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Phosphorylation of the myosin regulatory light chain (RLC) by Ca(2+)-calmodulin-activated myosin light chain kinase (MLCK) is known to be essential for the inotropic function of the heart. In this study, we have examined the effects of MLCK-phosphorylation of transgenic (Tg) mouse cardiac muscle preparations expressing the D166V (aspartic acid to valine)-RLC mutation, identified to cause familial hypertrophic cardiomyopathy with malignant outcomes. Our previous work with Tg-D166V mice demonstrated a large increase in the Ca(2+) sensitivity of contraction, reduced maximal ATPase and force and a decreased level of endogenous RLC phosphorylation. Based on studies demonstrating the beneficial and/or protective effects of cardiac myosin phosphorylation for heart function, we hypothesized that an ex vivo phosphorylation of Tg-D166V cardiac muscle may rescue the detrimental contractile phenotypes observed earlier at the level of single myosin molecules and in Tg-D166V papillary muscle fibres. We showed that MLCK-induced phosphorylation of Tg-D166V cardiac myofibrils and muscle fibres was able to increase the reduced myofibrillar ATPase and reverse an abnormally increased Ca(2+) sensitivity of force to the level observed for Tg-wild-type (WT) muscle. However, in contrast to Tg-WT, which displayed a phosphorylation-induced increase in steady-state force, the maximal tension in Tg-D166V papillary muscle fibres decreased upon phosphorylation. With the exception of force generation data, our results support the notion that RLC phosphorylation works as a rescue mechanism alleviating detrimental functional effects of a disease causing mutation. Further studies are necessary to elucidate the mechanism of this unexpected phosphorylation-induced decrease in maximal tension in Tg-D166V-skinned muscle fibres.
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Affiliation(s)
- Priya Muthu
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL 33136, USA
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39
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Moore JR, Leinwand L, Warshaw DM. Understanding cardiomyopathy phenotypes based on the functional impact of mutations in the myosin motor. Circ Res 2012; 111:375-85. [PMID: 22821910 DOI: 10.1161/circresaha.110.223842] [Citation(s) in RCA: 147] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Hypertrophic (HCM) and dilated (DCM) cardiomyopathies are inherited diseases with a high incidence of death due to electric abnormalities or outflow tract obstruction. In many of the families afflicted with either disease, causative mutations have been identified in various sarcomeric proteins. In this review, we focus on mutations in the cardiac muscle molecular motor, myosin, and its associated light chains. Despite the >300 identified mutations, there is still no clear understanding of how these mutations within the same myosin molecule can lead to the dramatically different clinical phenotypes associated with HCM and DCM. Localizing mutations within myosin's molecular structure provides insight into the potential consequence of these perturbations to key functional domains of the motor. Review of biochemical and biophysical data that characterize the functional capacities of these mutant myosins suggests that mutant myosins with enhanced contractility lead to HCM, whereas those displaying reduced contractility lead to DCM. With gain and loss of function potentially being the primary consequence of a specific mutation, how these functional changes trigger the hypertrophic response and lead to the distinct HCM and DCM phenotypes will be the future investigative challenge.
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Affiliation(s)
- Jeffrey R Moore
- Department of Physiology and Biophysics, Boston University School of Medicine, Boston, MA 02118, USA.
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40
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Heavy and light roles: myosin in the morphogenesis of the heart. Cell Mol Life Sci 2012; 70:1221-39. [PMID: 22955375 PMCID: PMC3602621 DOI: 10.1007/s00018-012-1131-1] [Citation(s) in RCA: 129] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2012] [Revised: 08/08/2012] [Accepted: 08/13/2012] [Indexed: 01/10/2023]
Abstract
Myosin is an essential component of cardiac muscle, from the onset of cardiogenesis through to the adult heart. Although traditionally known for its role in energy transduction and force development, recent studies suggest that both myosin heavy-chain and myosin light-chain proteins are required for a correctly formed heart. Myosins are structural proteins that are not only expressed from early stages of heart development, but when mutated in humans they may give rise to congenital heart defects. This review will discuss the roles of myosin, specifically with regards to the developing heart. The expression of each myosin protein will be described, and the effects that altering expression has on the heart in embryogenesis in different animal models will be discussed. The human molecular genetics of the myosins will also be reviewed.
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41
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Abstract
D166V point mutation in the ventricular myosin regulatory light chain (RLC) is one of the causes of familial hypertrophic cardiomyopathy (FHC). We show here that the rates of cross-bridge attachment and dissociation are significantly different in isometrically contracting cardiac myofibrils from right ventricle of WT and Tg-D166V mice. To avoid averaging over ensembles of molecules composing muscle fibers, the data was collected from a single molecule. Kinetics were derived by tracking the orientation of a single actin molecule by fluorescence anisotropy. Orientation oscillated between two states, corresponding to the actin-bound and actin-free states of the myosin cross-bridge. The cross-bridge in a wild-type (healthy) heart stayed attached and detached from thin filament on average for 0.7 and 2.7 s, respectively. In FHC heart, these numbers increased to 2.5 and 5.8 s, respectively. These findings suggest that alterations in myosin cross-bridge kinetics associated with D166V mutation of RLC ultimately affect the ability of a heart to efficiently pump the blood.
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42
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Wen JJ, Zago MP, Nuñez S, Gupta S, Burgos FN, Garg NJ. Serum proteomic signature of human chagasic patients for the identification of novel potential protein biomarkers of disease. Mol Cell Proteomics 2012; 11:435-52. [PMID: 22543060 DOI: 10.1074/mcp.m112.017640] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Chagas disease is initiated upon infection by Trypanosoma cruzi. Among the health consequences is a decline in heart function, and the pathophysiological mechanisms underlying this manifestation are not well understood. To explore the possible mechanisms, we employed IgY LC10 affinity chromatography in conjunction with ProteomeLab PF2D and two-dimensional gel electrophoresis to resolve the proteome signature of high and low abundance serum proteins in chagasic patients. MALDI-TOF MS/MS analysis yielded 80 and 14 differentially expressed proteins associated with cardiomyopathy of chagasic and other etiologies, respectively. The extent of oxidative stress-induced carbonyl modifications of the differentially expressed proteins (n = 26) was increased and coupled with a depression of antioxidant proteins. Functional annotation of the top networks developed by ingenuity pathway analysis of proteome database identified dysregulation of inflammation/acute phase response signaling and lipid metabolism relevant to production of prostaglandins and arachidonic acid in chagasic patients. Overlay of the major networks identified prothrombin and plasminogen at a nodal position with connectivity to proteome signature indicative of heart disease (i.e., thrombosis, angiogenesis, vasodilatation of blood vessels or the aorta, and increased permeability of blood vessel and endothelial tubes), and inflammatory responses (e.g., platelet aggregation, complement activation, and phagocyte activation and migration). The detection of cardiac proteins (myosin light chain 2 and myosin heavy chain 11) and increased levels of vinculin and plasminogen provided a comprehensive set of biomarkers of cardiac muscle injury and development of clinical Chagas disease in human patients. These results provide an impetus for biomarker validation in large cohorts of clinically characterized chagasic patients.
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Affiliation(s)
- Jian-Jun Wen
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas 77555-1070, USA
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43
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Wen JJ, Garg NJ. Proteome expression and carbonylation changes during Trypanosoma cruzi infection and Chagas disease in rats. Mol Cell Proteomics 2011; 11:M111.010918. [PMID: 22199233 DOI: 10.1074/mcp.m111.010918] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Inflammation and oxidative stress, elicited by Trypanosoma cruzi infection, are important pathologic events during progressive Chagasic cardiomyopathy. In this study, we infected Sprague-Dawley rats with T. cruzi, and treated with phenyl-α-tert-butylnitrone (PBN-antioxidant) and/or benznidazole (BZ-anti-parasite). We employed two-dimensional gel electrophoresis/mass spectrometry to investigate (a) the plasma proteomic changes associated with infection and disease development, and (b) the beneficial effects of PBN and BZ in controlling the disease-associated plasma profile. Matrix-assisted laser desorption ionization/time of flight (MALDI-TOF) tandem MS (MS/MS) analysis of differentially expressed (total 146) and oxidized (total 48) protein spots yielded 92 unique proteins. Our data showed that treatment with PBN and BZ restored the differential expression of 65% and 30% of the disease-associated proteins to normal level, respectively, and PBN prevented development of oxidative adducts on plasma proteins. Western blotting to detect dinitrophenyl-derivatized carbonyl-proteins revealed plasma proteins were maximally oxidized during acute infection. Functional and disease/disorder analyses allocated a majority of the differentially expressed and oxidized proteins into inflammation/immunity and lipid metabolism categories and to molecular pathways associated with heart disease (e.g. cardiac infarction, contractile dysfunction, hypertrophy, and hypertension) in chagasic rats, and to curative pathways (e.g. ROS scavenging capacity, immune regulation) in infected rats treated with PBN and/or BZ. We validated the two-dimensional gel electrophoresis results by Western blotting, and demonstrated that the disease-associated increased expression of gelsolin and vimentin and release of cardiac MYL2 in the plasma of chagasic rats was returned to control level by PBN/BZ treatment. Increased plasma levels of gelsolin, MYL2 and vimentin were directly correlated with the severity of cardiac disease in human chagasic patients. Together, these results demonstrate the plasma oxidative and inflammatory response profile, and plasma detection of cardiac proteins parallels the pathologic events contributing to Chagas disease development, and is of potential utility in diagnosing disease severity and designing suitable therapy for management of human chagasic patients.
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Affiliation(s)
- Jian-Jun Wen
- Department of Microbiology and Immunology, The University of Texas Medical Branch, Galveston, Texas 77555-1070, USA
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Olivotto I, Girolami F, Sciagrà R, Ackerman MJ, Sotgia B, Bos JM, Nistri S, Sgalambro A, Grifoni C, Torricelli F, Camici PG, Cecchi F. Microvascular function is selectively impaired in patients with hypertrophic cardiomyopathy and sarcomere myofilament gene mutations. J Am Coll Cardiol 2011; 58:839-48. [PMID: 21835320 DOI: 10.1016/j.jacc.2011.05.018] [Citation(s) in RCA: 111] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2010] [Revised: 04/28/2011] [Accepted: 05/24/2011] [Indexed: 11/26/2022]
Abstract
OBJECTIVES The purpose of this study was to assess myocardial blood flow (MBF) using positron emission tomography in patients with hypertrophic cardiomyopathy (HCM) according to genetic status. BACKGROUND Coronary microvascular dysfunction is an important feature of HCM, associated with ventricular remodeling and heart failure. We recently demonstrated the increased prevalence of systolic dysfunction in patients with HCM with sarcomere myofilament gene mutations and postulated an association between genetic status and coronary microvascular dysfunction. METHODS Maximum MBF (intravenous dipyridamole, 0.56 mg/kg; Dip-MBF) was measured using (13)N-labeled ammonia in 61 patients with HCM (age 38 ± 14 years), genotyped by automatic DNA sequencing of 8 myofilament-encoding genes (myosin-binding protein C, beta-myosin heavy chain, regulatory and essential light chains, troponin T, troponin I, troponin C, alpha-tropomyosin, and alpha-actin). In 35 patients, cardiac magnetic resonance imaging was performed. RESULTS Fifty-three mutations were identified in 42 of the 61 patients (genotype positive; 69%). Despite similar clinical profiles, genotype-positive patients with HCM showed substantially lower Dip-MBF compared with that of genotype-negative patients (1.7 ± 0.6 ml/min/g vs. 2.4 ± 1.2 ml/min/g; p < 0.02). A Dip-MBF <1.5 ml/min/g had 81% positive predictive value for genotype-positive status and implied a 3.5-fold independent increase in likelihood of carrying myofilament gene mutations (hazard ratio: 3.52; 95% confidence interval: 1.05 to 11.7; p = 0.04). At cardiac magnetic resonance imaging, the prevalence of late gadolinium enhancement was greater in genotype-positive patients (22 of 23 [96%] compared with 8 of 12 [67%] genotype-negative patients; p = 0.038). CONCLUSIONS Patients with HCM with sarcomere myofilament mutations are characterized by more severe impairment of microvascular function and increased prevalence of myocardial fibrosis, compared with genotype-negative individuals. These findings suggest a direct link between sarcomere gene mutations and adverse remodeling of the microcirculation in HCM, accounting for the increased long-term prevalence of ventricular dysfunction and heart failure in genotype-positive patients.
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Affiliation(s)
- Iacopo Olivotto
- Referral Center for Myocardial Diseases, Cytogenetics Unit and Department of Clinical Physiopathology, and Nuclear Medicine Unit, Careggi University Hospital, Florence, Italy.
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45
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Mettikolla P, Calander N, Luchowski R, Gryczynski I, Gryczynski Z, Zhao J, Szczesna-Cordary D, Borejdo J. Cross-bridge kinetics in myofibrils containing familial hypertrophic cardiomyopathy R58Q mutation in the regulatory light chain of myosin. J Theor Biol 2011; 284:71-81. [PMID: 21723297 PMCID: PMC3152379 DOI: 10.1016/j.jtbi.2011.06.014] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2011] [Revised: 06/09/2011] [Accepted: 06/14/2011] [Indexed: 12/16/2022]
Abstract
Familial hypertrophic cardiomyopathy (FHC) is a heritable form of cardiac hypertrophy caused by single-point mutations in genes encoding sarcomeric proteins including ventricular myosin regulatory light chain (RLC). FHC often leads to malignant outcomes and sudden cardiac death. The FHC mutations are believed to alter the kinetics of the interaction between actin and myosin resulting in inefficient energy utilization and compromised function of the heart. We studied the effect of the FHC-linked R58Q-RLC mutation on the kinetics of transgenic (Tg)-R58Q cardiac myofibrils. Kinetics was determined from the rate of change of orientation of actin monomers during muscle contraction. Actin monomers change orientation because myosin cross-bridges deliver periodic force impulses to it. An individual impulse (but not time average of impulses) carries the information about the kinetics of actomyosin interaction. To observe individual impulses it was necessary to scale down the experiments to the level of a few molecules. A small population (∼4 molecules) was selected by using (deliberately) inefficient fluorescence labeling and observing fluorescent molecules by a confocal microscope. We show that the kinetic rates are significantly smaller in the contracting cardiac myofibrils from Tg-R58Q mice then in control Tg-wild type (WT). We also demonstrate a lower force per cross-section of muscle fiber in Tg-R58Q versus Tg-WT mice. We conclude that the R58Q mutation-induced decrease in cross-bridge kinetics underlines the mechanism by which Tg-R58Q fibers develop low force and thus compromise the ability of the mutated heart to efficiently pump blood.
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Affiliation(s)
- P. Mettikolla
- Dept of Molecular Biology & Immunology and Center for Commercialization of Fluorescence Technologies, University of North Texas, Health Science Center, 3500 Camp Bowie Blvd, Fort Worth, TX 76107
| | - N. Calander
- Dept of Molecular Biology & Immunology and Center for Commercialization of Fluorescence Technologies, University of North Texas, Health Science Center, 3500 Camp Bowie Blvd, Fort Worth, TX 76107
- Dept of Physics, Macquarie University, Balaclava Rd, NSW 2109, Australia
| | - R. Luchowski
- Dept of Molecular Biology & Immunology and Center for Commercialization of Fluorescence Technologies, University of North Texas, Health Science Center, 3500 Camp Bowie Blvd, Fort Worth, TX 76107
| | - I. Gryczynski
- Dept of Cell Biology & Genetics and Center for Commercialization of FluorescenceTechnologies, University of North Texas, Health Science Center, 3500 Camp Bowie Blvd, Fort Worth, TX 76107
| | - Z. Gryczynski
- Dept of Molecular Biology & Immunology and Center for Commercialization of Fluorescence Technologies, University of North Texas, Health Science Center, 3500 Camp Bowie Blvd, Fort Worth, TX 76107
| | - J. Zhao
- Dept of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, 1600 NW 10Ave., Miami, FL 33136
| | - D. Szczesna-Cordary
- Dept of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, 1600 NW 10Ave., Miami, FL 33136
| | - J. Borejdo
- Dept of Molecular Biology & Immunology and Center for Commercialization of Fluorescence Technologies, University of North Texas, Health Science Center, 3500 Camp Bowie Blvd, Fort Worth, TX 76107
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Caleshu C, Sakhuja R, Nussbaum RL, Schiller NB, Ursell PC, Eng C, De Marco T, McGlothlin D, Burchard EG, Rame JE. Furthering the link between the sarcomere and primary cardiomyopathies: restrictive cardiomyopathy associated with multiple mutations in genes previously associated with hypertrophic or dilated cardiomyopathy. Am J Med Genet A 2011; 155A:2229-35. [PMID: 21823217 DOI: 10.1002/ajmg.a.34097] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2010] [Accepted: 04/12/2011] [Indexed: 01/21/2023]
Abstract
Mutations in genes that encode components of the sarcomere are well established as the cause of hypertrophic and dilated cardiomyopathies. Sarcomere genes, however, are increasingly being associated with other cardiomyopathies. One phenotype more recently recognized as a disease of the sarcomere is restrictive cardiomyopathy (RCM). We report on two patients with RCM associated with multiple mutations in sarcomere genes not previously associated with RCM. Patient 1 presented with NYHA Class III/IV heart failure at 22 years of age. She was diagnosed with RCM and advanced heart failure requiring heart transplantation. Sequencing of sarcomere genes revealed previously reported homozygous p.Glu143Lys mutations in MYL3, and a novel heterozygous p.Gly57Glu mutation in MYL2. The patient's mother is a double heterozygote for these mutations, with no evidence of cardiomyopathy. Patient 2 presented at 35 years of age with volume overload while hospitalized for oophorectomy. She was diagnosed with RCM and is being evaluated for heart transplantation. Sarcomere gene sequencing identified homozygous p.Asn279His mutations in TPM1. The patient's parents are consanguineous and confirmed heterozygotes. Her father was diagnosed with HCM at 42 years of age. This is the first report of mutations in TPM1, MYL3, and MYL2 associated with primary, non-hypertrophied RCM. The association of more sarcomere genes with RCM provides further evidence that mutations in the various sarcomere genes can cause different cardiomyopathy phenotypes. These cases also contribute to the growing body of evidence that multiple mutations have an additive effect on the severity of cardiomyopathies.
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Affiliation(s)
- Colleen Caleshu
- Stanford Center for Inherited Cardiovascular Disease, Stanford University Medical Center, Stanford, California 94305, USA.
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Abstract
In the 20 years since the discovery of the first mutation linked to familial hypertrophic cardiomyopathy (HCM), an astonishing number of mutations affecting numerous sarcomeric proteins have been described. Among the most prevalent of these are mutations that affect thick filament binding proteins, including the myosin essential and regulatory light chains and cardiac myosin binding protein (cMyBP)-C. However, despite the frequency with which myosin binding proteins, especially cMyBP-C, have been linked to inherited cardiomyopathies, the functional consequences of mutations in these proteins and the mechanisms by which they cause disease are still only partly understood. The purpose of this review is to summarize the known disease-causing mutations that affect the major thick filament binding proteins and to relate these mutations to protein function. Conclusions emphasize the impact that discovery of HCM-causing mutations has had on fueling insights into the basic biology of thick filament proteins and reinforce the idea that myosin binding proteins are dynamic regulators of the activation state of the thick filament that contribute to the speed and force of myosin-driven muscle contraction. Additional work is still needed to determine the mechanisms by which individual mutations induce hypertrophic phenotypes.
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Affiliation(s)
- Samantha P Harris
- Department of Neurobiology, Physiology, and Behavior College of Biological Sciences, University of California, One Shields Ave, Davis, CA 95616, USA.
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48
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Li Y, Wu G, Tang Q, Huang C, Jiang H, Shi L, Tu X, Huang J, Zhu X, Wang H. Slow cardiac myosin regulatory light chain 2 (MYL2) was down-expressed in chronic heart failure patients. Clin Cardiol 2010; 34:30-4. [PMID: 21259275 DOI: 10.1002/clc.20832] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
BACKGROUND Genetic studies have shown that many slow cardiac myosin regulatory light chain 2 (MYL2) gene mutations can cause hypertrophic cardiomyopathy, which is one of the most common causes of heart failure (HF). But until now there has been no pathological or histological evidence that MYL2 may be associated with HF development. Recent microarray studies indicated that myosin heavy chain expression changed in the pathological process of HF. Because MYL2 is a regulatory component of myosin heavy polypeptide, the role of MYL2 protein in HF needs to be studied. HYPOTHESIS The level of expression of MYL2 may change in the heart tissue of patients with chronic HF. METHODS We collected 28 human right auricle samples, 16 from chronic HF patients and 12 from healthy control subjects. Immunohistochemistry was carried out to observe the tissue-expression pattern of the MYL2 protein and Western blot methods were performed to quantify the relative MYL2 expression level. RESULTS In chronic HF patients, the MYL2 protein level decreased significantly compared with normal controls (t test P < 0.05). Among the 16 HF patients, MYL2 expression in the severe HF group (New York Heart Association [NYHA] class III or IV) was even lower than that of the moderate HF group (NYHA class II) (t test P < 0.05). CONCLUSIONS MYL2 was down-expressed in HF tissues, and our findings suggested that MYL2 may play a role in the development and progression of chronic HF.
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Affiliation(s)
- Yuanhong Li
- Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, People's Republic of China
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Greenberg MJ, Kazmierczak K, Szczesna-Cordary D, Moore JR. Cardiomyopathy-linked myosin regulatory light chain mutations disrupt myosin strain-dependent biochemistry. Proc Natl Acad Sci U S A 2010; 107:17403-8. [PMID: 20855589 PMCID: PMC2951453 DOI: 10.1073/pnas.1009619107] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Familial hypertrophic cardiomyopathy (FHC) is caused by mutations in sarcomeric proteins including the myosin regulatory light chain (RLC). Two such FHC mutations, R58Q and N47K, located near the cationic binding site of the RLC, have been identified from population studies. To examine the molecular basis for the observed phenotypes, we exchanged endogenous RLC from native porcine cardiac myosin with recombinant human ventricular wild type (WT) or FHC mutant RLC and examined the ability of the reconstituted myosin to propel actin filament sliding using the in vitro motility assay. We find that, whereas the mutant myosins are indistinguishable from the controls (WT or native myosin) under unloaded conditions, both R58Q- and N47K-exchanged myosins show reductions in force and power output compared with WT or native myosin. We also show that the changes in loaded kinetics are a result of mutation-induced loss of myosin strain sensitivity of ADP affinity. We propose that the R58Q and N47K mutations alter the mechanical properties of the myosin neck region, leading to altered load-dependent kinetics that may explain the observed mutant-induced FHC phenotypes.
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Affiliation(s)
- Michael J. Greenberg
- Department of Physiology and Biophysics, Boston University School of Medicine, Boston, MA 02118; and
| | - Katarzyna Kazmierczak
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL 33136
| | - Danuta Szczesna-Cordary
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL 33136
| | - Jeffrey R. Moore
- Department of Physiology and Biophysics, Boston University School of Medicine, Boston, MA 02118; and
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Borejdo J, Szczesna-Cordary D, Muthu P, Calander N. Familial hypertrophic cardiomyopathy can be characterized by a specific pattern of orientation fluctuations of actin molecules . Biochemistry 2010; 49:5269-77. [PMID: 20509708 DOI: 10.1021/bi1006749] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
A single-point mutation in the gene encoding the ventricular myosin regulatory light chain (RLC) is sufficient to cause familial hypertrophic cardiomyopathy (FHC). Most likely, the underlying cause of this disease is an inefficient energy utilization by the mutated cardiac muscle. We set out to devise a simple method to characterize two FHC phenotypes caused by the R58Q and D166V mutations in RLC. The method is based on the ability to observe a few molecules of actin in working ex vivo heart myofibril. Actin is labeled with extremely diluted fluorescent dye, and a small volume within the I-band ( approximately 10(-16) L), containing on average three actin molecules, is observed by confocal microscopy. During muscle contraction, myosin cross-bridges deliver cyclic impulses to actin. As a result, actin molecules undergo periodic fluctuations of orientation. We measured these fluctuations by recording the parallel and perpendicular components of fluorescent light emitted by an actin-bound fluorophore. The histograms of fluctuations of fluorescent actin molecules in wild-type (WT) hearts in rigor were represented by perfect Gaussian curves. In contrast, histograms of contracting heart muscle were peaked and asymmetric, suggesting that contraction occurred in at least two steps. Furthermore, the differences between histograms of contracting FHC R58Q and D166V hearts versus corresponding contracting WT hearts were statistically significant. On the basis of our results, we suggest a simple new method of distinguishing between healthy and FHC R58Q and D166V hearts by analyzing the probability distribution of polarized fluorescence intensity fluctuations of sparsely labeled actin molecules.
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Affiliation(s)
- J Borejdo
- Department of Molecular Biology and Immunology and Center for Commercialization of Fluorescence Technologies, University of North Texas Health Science Center, 3500 Camp Bowie Boulevard, Fort Worth, Texas 76107, USA.
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