1
|
Topriceanu CC, Pereira AC, Moon JC, Captur G, Ho CY. Meta-Analysis of Penetrance and Systematic Review on Transition to Disease in Genetic Hypertrophic Cardiomyopathy. Circulation 2024; 149:107-123. [PMID: 37929589 PMCID: PMC10775968 DOI: 10.1161/circulationaha.123.065987] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Accepted: 10/27/2023] [Indexed: 11/07/2023]
Abstract
BACKGROUND Hypertrophic cardiomyopathy (HCM) is characterized by unexplained left ventricular hypertrophy and is classically caused by pathogenic or likely pathogenic variants (P/LP) in genes encoding sarcomere proteins. Not all subclinical variant carriers will manifest clinically overt disease because penetrance (proportion of sarcomere or sarcomere-related P/LP variant carriers who develop disease) is variable, age dependent, and not reliably predicted. METHODS A systematic search of the literature was performed. We used random-effects generalized linear mixed model meta-analyses to contrast the cross-sectional prevalence and penetrance of sarcomere or sarcomere-related genes in 2 different contexts: clinically-based studies on patients and families with HCM versus population or community-based studies. Longitudinal family/clinical studies were additionally analyzed to investigate the rate of phenotypic conversion from subclinical to overt HCM during follow-up. RESULTS In total, 455 full-text manuscripts and articles were assessed. In family/clinical studies, the prevalence of sarcomere variants in patients diagnosed with HCM was 34%. The penetrance across all genes in nonproband relatives carrying P/LP variants identified during cascade screening was 57% (95% CI, 52%-63%), and the mean age at HCM diagnosis was 38 years (95% CI, 36%-40%). Penetrance varied from ≈32% for MYL3 (myosin light chain 3) to ≈55% for MYBPC3 (myosin-binding protein C3), ≈60% for TNNT2 (troponin T2) and TNNI3 (troponin I3), and ≈65% for MYH7 (myosin heavy chain 7). Population-based genetic studies demonstrate that P/LP sarcomere variants are present in the background population but at a low prevalence of <1%. The penetrance of HCM in incidentally identified P/LP variant carriers was also substantially lower at ≈11%, ranging from 0% in Atherosclerosis Risk in Communities to 18% in UK Biobank. In longitudinal family studies, the pooled phenotypic conversion across all genes was 15% over an average of ≈8 years of follow-up, starting from a mean of ≈16 years of age. However, short-term gene-specific phenotypic conversion varied between ≈12% for MYBPC3 and ≈23% for MYH7. CONCLUSIONS The penetrance of P/LP variants is highly variable and influenced by currently undefined and context-dependent genetic and environmental factors. Additional longitudinal studies are needed to improve our understanding of true lifetime penetrance in families and in the community and to identify drivers of the transition from subclinical to overt HCM.
Collapse
Affiliation(s)
- Constantin-Cristian Topriceanu
- Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA (C.-C.T., A.C.P., C.Y.H.). UCL Institute of Cardiovascular Science (C.-C.T., J.C.M., G.C.) and UCL MRC Unit for Lifelong Health and Ageing (G.C.), University College London, UK. Cardiac MRI Unit, Barts Heart Centre, West Smithfield, London, UK (C.-C.T., J.C.M.). The Royal Free Hospital, Centre for Inherited Heart Muscle Conditions, Cardiology Department, Hampstead, London, UK (G.C.)
| | - Alexandre C. Pereira
- Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA (C.-C.T., A.C.P., C.Y.H.). UCL Institute of Cardiovascular Science (C.-C.T., J.C.M., G.C.) and UCL MRC Unit for Lifelong Health and Ageing (G.C.), University College London, UK. Cardiac MRI Unit, Barts Heart Centre, West Smithfield, London, UK (C.-C.T., J.C.M.). The Royal Free Hospital, Centre for Inherited Heart Muscle Conditions, Cardiology Department, Hampstead, London, UK (G.C.)
| | - James C. Moon
- Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA (C.-C.T., A.C.P., C.Y.H.). UCL Institute of Cardiovascular Science (C.-C.T., J.C.M., G.C.) and UCL MRC Unit for Lifelong Health and Ageing (G.C.), University College London, UK. Cardiac MRI Unit, Barts Heart Centre, West Smithfield, London, UK (C.-C.T., J.C.M.). The Royal Free Hospital, Centre for Inherited Heart Muscle Conditions, Cardiology Department, Hampstead, London, UK (G.C.)
| | - Gabriella Captur
- Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA (C.-C.T., A.C.P., C.Y.H.). UCL Institute of Cardiovascular Science (C.-C.T., J.C.M., G.C.) and UCL MRC Unit for Lifelong Health and Ageing (G.C.), University College London, UK. Cardiac MRI Unit, Barts Heart Centre, West Smithfield, London, UK (C.-C.T., J.C.M.). The Royal Free Hospital, Centre for Inherited Heart Muscle Conditions, Cardiology Department, Hampstead, London, UK (G.C.)
| | - Carolyn Y. Ho
- Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA (C.-C.T., A.C.P., C.Y.H.). UCL Institute of Cardiovascular Science (C.-C.T., J.C.M., G.C.) and UCL MRC Unit for Lifelong Health and Ageing (G.C.), University College London, UK. Cardiac MRI Unit, Barts Heart Centre, West Smithfield, London, UK (C.-C.T., J.C.M.). The Royal Free Hospital, Centre for Inherited Heart Muscle Conditions, Cardiology Department, Hampstead, London, UK (G.C.)
| |
Collapse
|
2
|
Bang ML, Bogomolovas J, Chen J. Understanding the molecular basis of cardiomyopathy. Am J Physiol Heart Circ Physiol 2022; 322:H181-H233. [PMID: 34797172 PMCID: PMC8759964 DOI: 10.1152/ajpheart.00562.2021] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Revised: 11/16/2021] [Accepted: 11/16/2021] [Indexed: 02/03/2023]
Abstract
Inherited cardiomyopathies are a major cause of mortality and morbidity worldwide and can be caused by mutations in a wide range of proteins located in different cellular compartments. The present review is based on Dr. Ju Chen's 2021 Robert M. Berne Distinguished Lectureship of the American Physiological Society Cardiovascular Section, in which he provided an overview of the current knowledge on the cardiomyopathy-associated proteins that have been studied in his laboratory. The review provides a general summary of the proteins in different compartments of cardiomyocytes associated with cardiomyopathies, with specific focus on the proteins that have been studied in Dr. Chen's laboratory.
Collapse
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
| |
Collapse
|
3
|
Maekura K, Yamano R, Matsuura K, Kadoyama K, Matsuyama S, Hamada M, Takano M. Proteomic analysis of the heart in normal aging mice. THE JOURNAL OF MEDICAL INVESTIGATION 2022; 69:217-223. [PMID: 36244772 DOI: 10.2152/jmi.69.217] [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] [Indexed: 06/16/2023]
Abstract
Aging induces pathological cardiovascular changes such as cardiac dysfunction and arteriosclerosis. With aging, heart cells, especially, become more susceptible to lethal damage. In this report, we tried to understand the precise mechanism of myocardial change resulting from aging by examining the heart proteome in aging mice using two-dimensional gel electrophoresis (2DE). The proteins were stained with fluorescence dyes (SYPRO Ruby and Pro-Q Diamond) and identified by subsequent MALDI-TOF-MS / MS. As a result, markedly altered levels of 14 proteins and 7 phosphoproteins were detected in the hearts of 3-, 7-, 11-, and 20-month-old mice. The functions of these identified proteins and phosphoproteins were energy metabolism, muscle contraction, glycolysis, and cytoskeletal support. Additionally, the results of Western blotting confirmed changes in the expression of FTH, CPNE5, and SUCLA2. These findings showed that aging modified the expression of proteins and phosphoproteins in the heart. We suggest that changes in the expression of these proteins are critical to the development of cardiac dysfunction resulting from aging. J. Med. Invest. 69 : 217-223, August, 2022.
Collapse
Affiliation(s)
- Koji Maekura
- Laboratory of Molecular Cellular Biology, School of Pharmaceutical Sciences, Kobe Gakuin University, 1-1-3 Minatojima, Chuo-ku, Kobe 650-8586, Japan
| | - Ryo Yamano
- Laboratory of Molecular Cellular Biology, School of Pharmaceutical Sciences, Kobe Gakuin University, 1-1-3 Minatojima, Chuo-ku, Kobe 650-8586, Japan
| | - Kenji Matsuura
- Laboratory of Toxicology, Faculty of Pharmacy, Osaka Ohtani University, 3-11-1 Nishikigorikita, Tondabayashi, Osaka 584-8540, Japan
| | - Keiichi Kadoyama
- Faculty of Pharmaceutical Sciences, Himeji Dokkyo University, 7-2-1 Kamiohno, Himeji 670-8524, Japan
| | - Shogo Matsuyama
- Biosignal Research Center, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe 657-8501, Japan
| | - Michiko Hamada
- Laboratory of Molecular Cellular Biology, School of Pharmaceutical Sciences, Kobe Gakuin University, 1-1-3 Minatojima, Chuo-ku, Kobe 650-8586, Japan
| | - Masaoki Takano
- Laboratory of Molecular Cellular Biology, School of Pharmaceutical Sciences, Kobe Gakuin University, 1-1-3 Minatojima, Chuo-ku, Kobe 650-8586, Japan
| |
Collapse
|
4
|
Regulation of myosin light-chain phosphorylation and its roles in cardiovascular physiology and pathophysiology. Hypertens Res 2022; 45:40-52. [PMID: 34616031 DOI: 10.1038/s41440-021-00733-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 06/19/2021] [Accepted: 07/08/2021] [Indexed: 01/22/2023]
Abstract
The regulation of muscle contraction is a critical function in the cardiovascular system, and abnormalities may be life-threatening or cause illness. The common basic mechanism in muscle contraction is the interaction between the protein filaments myosin and actin. Although this interaction is primarily regulated by intracellular Ca2+, the primary targets and intracellular signaling pathways differ in vascular smooth muscle and cardiac muscle. Phosphorylation of the myosin regulatory light chain (RLC) is a primary molecular switch for smooth muscle contraction. The equilibrium between phosphorylated and unphosphorylated RLC is dynamically achieved through two enzymes, myosin light chain kinase, a Ca2+-dependent enzyme, and myosin phosphatase, which modifies the Ca2+ sensitivity of contractions. In cardiac muscle, the primary target protein for Ca2+ is troponin C on thin filaments; however, RLC phosphorylation also plays a modulatory role in contraction. This review summarizes recent advances in our understanding of the regulation, physiological function, and pathophysiological involvement of RLC phosphorylation in smooth and cardiac muscles.
Collapse
|
5
|
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.
Collapse
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.
| |
Collapse
|
6
|
Rasicci DV, Kirkland O, Moonschi FH, Wood NB, Szczesna-Cordary D, Previs MJ, Wenk JF, Campbell KS, Yengo CM. Impact of regulatory light chain mutation K104E on the ATPase and motor properties of cardiac myosin. J Gen Physiol 2021; 153:212025. [PMID: 33891674 PMCID: PMC8077168 DOI: 10.1085/jgp.202012811] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Accepted: 03/19/2021] [Indexed: 12/11/2022] Open
Abstract
Mutations in the cardiac myosin regulatory light chain (RLC, MYL2 gene) are known to cause inherited cardiomyopathies with variable phenotypes. In this study, we investigated the impact of a mutation in the RLC (K104E) that is associated with hypertrophic cardiomyopathy (HCM). Previously in a mouse model of K104E, older animals were found to develop cardiac hypertrophy, fibrosis, and diastolic dysfunction, suggesting a slow development of HCM. However, variable penetrance of the mutation in human populations suggests that the impact of K104E may be subtle. Therefore, we generated human cardiac myosin subfragment-1 (M2β-S1) and exchanged on either the wild type (WT) or K104E human ventricular RLC in order to assess the impact of the mutation on the mechanochemical properties of cardiac myosin. The maximum actin-activated ATPase activity and actin sliding velocities in the in vitro motility assay were similar in M2β-S1 WT and K104E, as were the detachment kinetic parameters, including the rate of ATP-induced dissociation and the ADP release rate constant. We also examined the mechanical performance of α-cardiac myosin extracted from transgenic (Tg) mice expressing human wild type RLC (Tg WT) or mutant RLC (Tg K104E). We found that α-cardiac myosin from Tg K104E animals demonstrated enhanced actin sliding velocities in the motility assay compared with its Tg WT counterpart. Furthermore, the degree of incorporation of the mutant RLC into α-cardiac myosin in the transgenic animals was significantly reduced compared with wild type. Therefore, we conclude that the impact of the K104E mutation depends on either the length or the isoform of the myosin heavy chain backbone and that the mutation may disrupt RLC interactions with the myosin lever arm domain.
Collapse
Affiliation(s)
- David V Rasicci
- Pennsylvania State University College of Medicine, Hershey, PA
| | | | | | | | | | | | | | | | | |
Collapse
|
7
|
Awinda PO, Watanabe M, Bishaw Y, Huckabee AM, Agonias KB, Kazmierczak K, Szczesna-Cordary D, Tanner BCW. Mavacamten decreases maximal force and Ca 2+ sensitivity in the N47K-myosin regulatory light chain mouse model of hypertrophic cardiomyopathy. Am J Physiol Heart Circ Physiol 2021; 320:H881-H890. [PMID: 33337957 PMCID: PMC8082789 DOI: 10.1152/ajpheart.00345.2020] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Revised: 12/10/2020] [Accepted: 12/10/2020] [Indexed: 01/12/2023]
Abstract
Morbidity and mortality associated with heart disease is a growing threat to the global population, and novel therapies are needed. Mavacamten (formerly called MYK-461) is a small molecule that binds to cardiac myosin and inhibits myosin ATPase. Mavacamten is currently in clinical trials for the treatment of obstructive hypertrophic cardiomyopathy (HCM), and it may provide benefits for treating other forms of heart disease. We investigated the effect of mavacamten on cardiac muscle contraction in two transgenic mouse lines expressing the human isoform of cardiac myosin regulatory light chain (RLC) in their hearts. Control mice expressed wild-type RLC (WT-RLC), and HCM mice expressed the N47K RLC mutation. In the absence of mavacamten, skinned papillary muscle strips from WT-RLC mice produced greater isometric force than strips from N47K mice. Adding 0.3 µM mavacamten decreased maximal isometric force and reduced Ca2+ sensitivity of contraction for both genotypes, but this reduction in pCa50 was nearly twice as large for WT-RLC versus N47K. We also used stochastic length-perturbation analysis to characterize cross-bridge kinetics. The cross-bridge detachment rate was measured as a function of [MgATP] to determine the effect of mavacamten on myosin nucleotide handling rates. Mavacamten increased the MgADP release and MgATP binding rates for both genotypes, thereby contributing to faster cross-bridge detachment, which could speed up myocardial relaxation during diastole. Our data suggest that mavacamten reduces isometric tension and Ca2+ sensitivity of contraction via decreased strong cross-bridge binding. Mavacamten may become a useful therapy for patients with heart disease, including some forms of HCM.NEW & NOTEWORTHY Mavacamten is a pharmaceutical that binds to myosin, and it is under investigation as a therapy for some forms of heart disease. We show that mavacamten reduces isometric tension and Ca2+ sensitivity of contraction in skinned myocardial strips from a mouse model of hypertrophic cardiomyopathy that expresses the N47K mutation in cardiac myosin regulatory light chain. Mavacamten reduces contractility by decreasing strong cross-bridge binding, partially due to faster cross-bridge nucleotide handling rates that speed up myosin detachment.
Collapse
Affiliation(s)
- Peter O Awinda
- Department of Integrative Physiology and Neuroscience, Washington State University, Pullman, Washington
| | - Marissa Watanabe
- Department of Integrative Physiology and Neuroscience, Washington State University, Pullman, Washington
| | - Yemeserach Bishaw
- Department of Integrative Physiology and Neuroscience, Washington State University, Pullman, Washington
| | - Anna M Huckabee
- Department of Integrative Physiology and Neuroscience, Washington State University, Pullman, Washington
| | - Keinan B Agonias
- Department of Integrative Physiology and Neuroscience, Washington State University, Pullman, Washington
| | - Katarzyna Kazmierczak
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida
| | - Danuta Szczesna-Cordary
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida
| | - Bertrand C W Tanner
- Department of Integrative Physiology and Neuroscience, Washington State University, Pullman, Washington
| |
Collapse
|
8
|
Shaboodien G, Spracklen TF, Kamuli S, Ndibangwi P, Van Niekerk C, Ntusi NAB. Genetics of inherited cardiomyopathies in Africa. Cardiovasc Diagn Ther 2020; 10:262-278. [PMID: 32420109 DOI: 10.21037/cdt.2019.10.03] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
In sub-Saharan Africa (SSA), the burden of noncommunicable diseases (NCDs) is rising disproportionately in comparison to the rest of the world, affecting urban, semi-urban and rural dwellers alike. NCDs are predicted to surpass infections like human immunodeficiency virus, tuberculosis and malaria as the leading cause of mortality in SSA over the next decade. Heart failure (HF) is the dominant form of cardiovascular disease (CVD), and a leading cause of NCD in SSA. The main causes of HF in SSA are hypertension, cardiomyopathies, rheumatic heart disease, pericardial disease, and to a lesser extent, coronary heart disease. Of these, the cardiomyopathies deserve greater attention because of the relatively poor understanding of mechanisms of disease, poor outcomes and the disproportionate impact they have on young, economically active individuals. Morphofunctionally, cardiomyopathies are classified as dilated, hypertrophic, restrictive and arrhythmogenic; regardless of classification, at least half of these are inherited forms of CVD. In this review, we summarise all studies that have investigated the incidence of cardiomyopathy across Africa, with a focus on the inherited cardiomyopathies. We also review data on the molecular genetic underpinnings of cardiomyopathy in Africa, where there is a striking lack of studies reporting on the genetics of cardiomyopathy. We highlight the impact that genetic testing, through candidate gene screening, association studies and next generation sequencing technologies such as whole exome sequencing and targeted resequencing has had on the understanding of cardiomyopathy in Africa. Finally, we emphasise the need for future studies to fill large gaps in our knowledge in relation to the genetics of inherited cardiomyopathies in Africa.
Collapse
Affiliation(s)
- Gasnat Shaboodien
- Cardiovascular Genetics Laboratory, Hatter Institute for Cardiovascular Research in Africa, Department of Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa.,Department of Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Timothy F Spracklen
- Cardiovascular Genetics Laboratory, Hatter Institute for Cardiovascular Research in Africa, Department of Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa.,Department of Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Stephen Kamuli
- Cardiovascular Genetics Laboratory, Hatter Institute for Cardiovascular Research in Africa, Department of Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa.,Department of Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Polycarp Ndibangwi
- Cardiovascular Genetics Laboratory, Hatter Institute for Cardiovascular Research in Africa, Department of Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa.,Department of Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Carla Van Niekerk
- Cardiovascular Genetics Laboratory, Hatter Institute for Cardiovascular Research in Africa, Department of Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa.,Department of Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Ntobeko A B Ntusi
- Cardiovascular Genetics Laboratory, Hatter Institute for Cardiovascular Research in Africa, Department of Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa.,Department of Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa.,Cape Universities Body Imaging Centre, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| |
Collapse
|
9
|
Zaleta-Rivera K, Dainis A, Ribeiro AJS, Cordero P, Rubio G, Shang C, Liu J, Finsterbach T, Parikh VN, Sutton S, Seo K, Sinha N, Jain N, Huang Y, Hajjar RJ, Kay MA, Szczesna-Cordary D, Pruitt BL, Wheeler MT, Ashley EA. Allele-Specific Silencing Ameliorates Restrictive Cardiomyopathy Attributable to a Human Myosin Regulatory Light Chain Mutation. Circulation 2019; 140:765-778. [PMID: 31315475 DOI: 10.1161/circulationaha.118.036965] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Restrictive cardiomyopathy is a rare heart disease associated with mutations in sarcomeric genes and with phenotypic overlap with hypertrophic cardiomyopathy. There is no approved therapy directed at the underlying cause. Here, we explore the potential of an interfering RNA (RNAi) therapeutic for a human sarcomeric mutation in MYL2 causative of restrictive cardiomyopathy in a mouse model. METHODS A short hairpin RNA (M7.8L) was selected from a pool for specificity and efficacy. Two groups of myosin regulatory light chain N47K transgenic mice were injected with M7.8L packaged in adeno-associated virus 9 at 3 days of age and 60 days of age. Mice were subjected to treadmill exercise and echocardiography after treatment to determine maximal oxygen uptake and left ventricular mass. At the end of treatment, heart, lung, liver, and kidney tissue was harvested to determine viral tropism and for transcriptomic and proteomic analysis. Cardiomyocytes were isolated for single-cell studies. RESULTS A one-time injection of AAV9-M7.8L RNAi in 3-day-old humanized regulatory light chain mutant transgenic mice silenced the mutated allele (RLC-47K) with minimal effects on the normal allele (RLC-47N) assayed at 16 weeks postinjection. AAV9-M7.8L RNAi suppressed the expression of hypertrophic biomarkers, reduced heart weight, and attenuated a pathological increase in left ventricular mass. Single adult cardiac myocytes from mice treated with AAV9-M7.8L showed partial restoration of contraction, relaxation, and calcium kinetics. In addition, cardiac stress protein biomarkers, such as calmodulin-dependent protein kinase II and the transcription activator Brg1 were reduced, suggesting recovery toward a healthy myocardium. Transcriptome analyses further revealed no significant changes of argonaute (AGO1, AGO2) and endoribonuclease dicer (DICER1) transcripts, and endogenous microRNAs were preserved, suggesting that the RNAi pathway was not saturated. CONCLUSIONS Our results show the feasibility, efficacy, and safety of RNAi therapeutics directed towards human restrictive cardiomyopathy. This is a promising step toward targeted therapy for a prevalent human disease.
Collapse
Affiliation(s)
- Kathia Zaleta-Rivera
- Division of Cardiovascular Medicine (K.Z.-R., A.D., P.C., G.R., C.S., J.L., T.F., W.N.P., S.S., K.S., N.S., N.J., Y.H., M.T.W., E.A.A.), Stanford University School of Medicine, CA
| | - Alexandra Dainis
- Division of Cardiovascular Medicine (K.Z.-R., A.D., P.C., G.R., C.S., J.L., T.F., W.N.P., S.S., K.S., N.S., N.J., Y.H., M.T.W., E.A.A.), Stanford University School of Medicine, CA
| | | | - Pablo Cordero
- Division of Cardiovascular Medicine (K.Z.-R., A.D., P.C., G.R., C.S., J.L., T.F., W.N.P., S.S., K.S., N.S., N.J., Y.H., M.T.W., E.A.A.), Stanford University School of Medicine, CA
| | - Gabriel Rubio
- Division of Cardiovascular Medicine (K.Z.-R., A.D., P.C., G.R., C.S., J.L., T.F., W.N.P., S.S., K.S., N.S., N.J., Y.H., M.T.W., E.A.A.), Stanford University School of Medicine, CA
| | - Ching Shang
- Division of Cardiovascular Medicine (K.Z.-R., A.D., P.C., G.R., C.S., J.L., T.F., W.N.P., S.S., K.S., N.S., N.J., Y.H., M.T.W., E.A.A.), Stanford University School of Medicine, CA
| | - Jing Liu
- Division of Cardiovascular Medicine (K.Z.-R., A.D., P.C., G.R., C.S., J.L., T.F., W.N.P., S.S., K.S., N.S., N.J., Y.H., M.T.W., E.A.A.), Stanford University School of Medicine, CA
| | - Thomas Finsterbach
- Division of Cardiovascular Medicine (K.Z.-R., A.D., P.C., G.R., C.S., J.L., T.F., W.N.P., S.S., K.S., N.S., N.J., Y.H., M.T.W., E.A.A.), Stanford University School of Medicine, CA
| | - Victoria N Parikh
- Division of Cardiovascular Medicine (K.Z.-R., A.D., P.C., G.R., C.S., J.L., T.F., W.N.P., S.S., K.S., N.S., N.J., Y.H., M.T.W., E.A.A.), Stanford University School of Medicine, CA
| | - Shirley Sutton
- Division of Cardiovascular Medicine (K.Z.-R., A.D., P.C., G.R., C.S., J.L., T.F., W.N.P., S.S., K.S., N.S., N.J., Y.H., M.T.W., E.A.A.), Stanford University School of Medicine, CA
| | - Kinya Seo
- Division of Cardiovascular Medicine (K.Z.-R., A.D., P.C., G.R., C.S., J.L., T.F., W.N.P., S.S., K.S., N.S., N.J., Y.H., M.T.W., E.A.A.), Stanford University School of Medicine, CA
| | - Nikita Sinha
- Division of Cardiovascular Medicine (K.Z.-R., A.D., P.C., G.R., C.S., J.L., T.F., W.N.P., S.S., K.S., N.S., N.J., Y.H., M.T.W., E.A.A.), Stanford University School of Medicine, CA
| | - Nikhil Jain
- Division of Cardiovascular Medicine (K.Z.-R., A.D., P.C., G.R., C.S., J.L., T.F., W.N.P., S.S., K.S., N.S., N.J., Y.H., M.T.W., E.A.A.), Stanford University School of Medicine, CA
| | - Yong Huang
- Division of Cardiovascular Medicine (K.Z.-R., A.D., P.C., G.R., C.S., J.L., T.F., W.N.P., S.S., K.S., N.S., N.J., Y.H., M.T.W., E.A.A.), Stanford University School of Medicine, CA
| | - Roger J Hajjar
- Cardiovascular Institute, Cardiovascular Research Center at Icahn School of Medicine at Mount Sinai, New York, NY (R.J.H.)
| | - Mark A Kay
- Department of Genetics (M.A.K., E.A.A.), Stanford University School of Medicine, CA
- Department of Pediatrics (M.A.K.), Stanford University School of Medicine, CA
| | - Danuta Szczesna-Cordary
- Department of Molecular and Cellular Pharmacology, University of Miami Leonard M. Miller School of Medicine, FL (D.S.-C.)
| | - Beth L Pruitt
- Department of Mechanical Engineering, Stanford University, CA (A.J.S.R., B.L.P.)
| | - Matthew T Wheeler
- Division of Cardiovascular Medicine (K.Z.-R., A.D., P.C., G.R., C.S., J.L., T.F., W.N.P., S.S., K.S., N.S., N.J., Y.H., M.T.W., E.A.A.), Stanford University School of Medicine, CA
| | - Euan A Ashley
- Division of Cardiovascular Medicine (K.Z.-R., A.D., P.C., G.R., C.S., J.L., T.F., W.N.P., S.S., K.S., N.S., N.J., Y.H., M.T.W., E.A.A.), Stanford University School of Medicine, CA
- Department of Genetics (M.A.K., E.A.A.), Stanford University School of Medicine, CA
| |
Collapse
|
10
|
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.
Collapse
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
Collapse
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.
| |
Collapse
|
11
|
Wang L, Kazmierczak K, Yuan CC, Yadav S, Kawai M, Szczesna-Cordary D. Cardiac contractility, motor function, and cross-bridge kinetics in N47K-RLC mutant mice. FEBS J 2017; 284:1897-1913. [PMID: 28467684 DOI: 10.1111/febs.14096] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2017] [Revised: 03/17/2017] [Accepted: 04/27/2017] [Indexed: 12/28/2022]
Abstract
We have investigated the physiology and mechanical profiles of skinned papillary muscle fibers from transgenic mice expressing the N47K mutation in the myosin regulatory light chain (RLC), shown to cause hypertrophic cardiomyopathy in humans. The results were compared with wild-type (WT) mice, both expressing the human ventricular RLC. Rate constants of a cross-bridge (XB) cycle were deduced from tension transients induced by sinusoidal length changes during maximal Ca2+ activation, and were studied as a function of MgATP, MgADP, and Pi concentrations. N47K mutant showed slower XB cycles but higher actin-activated ATPase activity compared with WT. Consequently, N47K exhibited larger tension than WT. K0 (ADP association constant) and K4 (equilibrium constant of force generation) were larger in N47K, and K1 (ATP association constant) was slightly larger in N47K vs. WT, demonstrating stronger nucleotide binding and force generation abilities of the mutant, but no changes in rigor acto-myosin binding were observed. Tension per XB was similar among groups, but N47K exhibited more XB distribution in the attached state. Larger values of tension and higher ATPase in N47K suggested that more cross-bridges participated in tension production in the mutant myocardium compared with WT. In vivo analysis of heart function, performed in ~ 12.5-month-old mice by echocardiography and invasive hemodynamics, demonstrated a significant decrease in dP/dtmax -end-diastolic volume relationship, indicating a depression of ventricular contractility in N47K mice. Our findings suggest that the N47K mutation exerts its action through direct alterations of myosin motor function that ultimately result in pathological hypertrophic remodeling in N47K hearts.
Collapse
Affiliation(s)
- Li Wang
- Departments of Anatomy and Cell Biology and Internal Medicine, University of Iowa, IA, USA
| | - Katarzyna Kazmierczak
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, FL, USA
| | - Chen-Ching Yuan
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, FL, USA
| | - Sunil Yadav
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, FL, USA
| | - Masataka Kawai
- Departments of Anatomy and Cell Biology and Internal Medicine, University of Iowa, IA, USA
| | - Danuta Szczesna-Cordary
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, FL, USA
| |
Collapse
|
12
|
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.
Collapse
|
13
|
Jaafar N, Gómez J, Kammoun I, Zairi I, Amara WB, Kachboura S, Kraiem S, Hammami M, Iglesias S, Alonso B, Coto E. Spectrum of Mutations in Hypertrophic Cardiomyopathy Genes Among Tunisian Patients. Genet Test Mol Biomarkers 2016; 20:674-679. [PMID: 27574918 DOI: 10.1089/gtmb.2016.0187] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
BACKGROUND Hypertrophic cardiomyopathy (HCM) is a common cardiac genetic disorder associated with heart failure and sudden death. Mutations in the cardiac sarcomere genes are found in approximately half of HCM patients and are more common among cases with a family history of the disease. Data about the mutational spectrum of the sarcomeric genes in HCM patients from Northern Africa are limited. The population of Tunisia is particularly interesting due to its Berber genetic background. As founder mutations have been reported in other disorders. METHODS We performed semiconductor chip (Ion Torrent PGM) next generation sequencing of the nine main sarcomeric genes (MYH7, MYBPC3, TNNT2, TNNI3, ACTC1, TNNC1, MYL2, MYL3, TPM1) as well as the recently identified as an HCM gene, FLNC, in 45 Tunisian HCM patients. RESULTS We found sarcomere gene polymorphisms in 12 patients (27%), with MYBPC3 and MYH7 representing 83% (10/12) of the mutations. One patient was homozygous for a new MYL3 mutation and two were double MYBPC3 + MYH7 mutation carriers. Screening of the FLNC gene identified three new mutations, which points to FLNC mutations as an important cause of HCM among Tunisians. CONCLUSION The mutational background of HCM in Tunisia is heterogeneous. Unlike other Mendelian disorders, there were no highly prevalent mutations that could explain most of the cases. Our study also suggested that FLNC mutations may play a role on the risk for HCM among Tunisians.
Collapse
Affiliation(s)
- Nawel Jaafar
- 1 Biochemistry Laboratory LR12ES05 "Nutrition-Functional Food & Vascular Health," USCR Mass Spectrometry, Faculty of Medicine, University of Monastir , Monastir, Tunisia
| | - Juan Gómez
- 2 Unidad de Referencia de Cardiopatías Familiares-HUCA, Genética Molecular y Cardiología, Hospital Universitario Central Asturias , Oviedo, Spain
| | - Ikram Kammoun
- 3 Department of Cardiology, Abderrahmen Mami Hospital , Tunis, Tunisia
| | - Ihsen Zairi
- 4 Department of Cardiology, Habib Thameur Hospital , Tunis, Tunisia
| | - Wael Ben Amara
- 3 Department of Cardiology, Abderrahmen Mami Hospital , Tunis, Tunisia
| | - Salem Kachboura
- 3 Department of Cardiology, Abderrahmen Mami Hospital , Tunis, Tunisia
| | - Sondes Kraiem
- 4 Department of Cardiology, Habib Thameur Hospital , Tunis, Tunisia
| | - Mohamed Hammami
- 1 Biochemistry Laboratory LR12ES05 "Nutrition-Functional Food & Vascular Health," USCR Mass Spectrometry, Faculty of Medicine, University of Monastir , Monastir, Tunisia
| | - Sara Iglesias
- 2 Unidad de Referencia de Cardiopatías Familiares-HUCA, Genética Molecular y Cardiología, Hospital Universitario Central Asturias , Oviedo, Spain
| | - Belén Alonso
- 2 Unidad de Referencia de Cardiopatías Familiares-HUCA, Genética Molecular y Cardiología, Hospital Universitario Central Asturias , Oviedo, Spain
| | - Eliecer Coto
- 2 Unidad de Referencia de Cardiopatías Familiares-HUCA, Genética Molecular y Cardiología, Hospital Universitario Central Asturias , Oviedo, Spain .,5 Departamento de Medicina, Universidad de Oviedo , Oviedo, Spain
| |
Collapse
|
14
|
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.
Collapse
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.
| |
Collapse
|
15
|
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.
Collapse
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
| |
Collapse
|
16
|
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.
Collapse
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
| |
Collapse
|
17
|
Santori M, Blanco-Verea A, Gil R, Cortis J, Becker K, Schneider PM, Carracedo A, Brion M. Broad-based molecular autopsy: a potential tool to investigate the involvement of subtle cardiac conditions in sudden unexpected death in infancy and early childhood. Arch Dis Child 2015; 100:952-6. [PMID: 26272908 DOI: 10.1136/archdischild-2015-308200] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/08/2015] [Accepted: 07/01/2015] [Indexed: 12/25/2022]
Abstract
OBJECTIVES Sudden unexplained death in children is a tragic and traumatic event, often worsened when the cause of death cannot be determined. This work aimed to investigate the presence of putative pathogenic genetic variants in a broad spectrum of cardiomyopathy, channelopathy and aortic disease associated genes that may have increased these children's vulnerability to sudden cardiac death. DESIGN We performed molecular autopsy of 41 cases of sudden unexplained death in infants and children through massive parallel sequencing of up to 86 sudden cardiac death-related genes. Multiple in silico analyses were conducted together with a thorough review of the literature in order to prioritise the putative pathogenic variants. RESULTS A total of 63 variants in 35 cases were validated. The largest proportion of these variants is located within cardiomyopathy genes although this would have been more expected of channelopathy gene variants. Subtle microscopic features of heart tissue may indicate the presence of an early onset cardiomyopathy as a predisposing condition to sudden unexpected death in some individuals. CONCLUSIONS Next-generation sequencing technologies reveal the existence of a wide spectrum of rare and novel genetic variants in sarcomere genes, compared with that of cardiac ion channels, in sudden unexplained death in infants and children. Our findings encourage further investigation of the role of early onset inherited cardiomyopathies and other diseases involving myocardial dysfunction in these deaths. Early detection of variants in these individuals could help to unmask subtle forms of disease within their relatives, who would eventually benefit from better counselling about their genetic history.
Collapse
Affiliation(s)
- Montserrat Santori
- Xenética de Enfermidades Cardiovasculares, Instituto de Investigación Sanitaria de Santiago, Red de Investigación Cardiovascular (RIC), Santiago De Compostela, Spain Grupo de Medicina Xenómica, University of Santiago de Compostela, Santiago de Compostela, Spain Fundación Pública Galega de Medicina Xenómica, SERGAS, Santiago de Compostela, Spain
| | - Alejandro Blanco-Verea
- Xenética de Enfermidades Cardiovasculares, Instituto de Investigación Sanitaria de Santiago, Red de Investigación Cardiovascular (RIC), Santiago De Compostela, Spain Grupo de Medicina Xenómica, University of Santiago de Compostela, Santiago de Compostela, Spain Fundación Pública Galega de Medicina Xenómica, SERGAS, Santiago de Compostela, Spain
| | - Rocio Gil
- Xenética de Enfermidades Cardiovasculares, Instituto de Investigación Sanitaria de Santiago, Red de Investigación Cardiovascular (RIC), Santiago De Compostela, Spain Grupo de Medicina Xenómica, University of Santiago de Compostela, Santiago de Compostela, Spain Fundación Pública Galega de Medicina Xenómica, SERGAS, Santiago de Compostela, Spain
| | - Judith Cortis
- Faculty of Medicine, Institute of Legal Medicine, University of Cologne, Cologne, Germany
| | - Katrin Becker
- Faculty of Medicine, Institute of Legal Medicine, University of Cologne, Cologne, Germany
| | - Peter M Schneider
- Faculty of Medicine, Institute of Legal Medicine, University of Cologne, Cologne, Germany
| | - Angel Carracedo
- Grupo de Medicina Xenómica, University of Santiago de Compostela, Santiago de Compostela, Spain Fundación Pública Galega de Medicina Xenómica, SERGAS, Santiago de Compostela, Spain Center of Excellence in Genomic Medicine Research, King Abdulaziz University Jeddah, Kingdom of Saudi Arabia
| | - Maria Brion
- Xenética de Enfermidades Cardiovasculares, Instituto de Investigación Sanitaria de Santiago, Red de Investigación Cardiovascular (RIC), Santiago De Compostela, Spain Grupo de Medicina Xenómica, University of Santiago de Compostela, Santiago de Compostela, Spain Fundación Pública Galega de Medicina Xenómica, SERGAS, Santiago de Compostela, Spain
| |
Collapse
|
18
|
Huang W, Szczesna-Cordary D. Molecular mechanisms of cardiomyopathy phenotypes associated with myosin light chain mutations. J Muscle Res Cell Motil 2015; 36:433-45. [PMID: 26385864 DOI: 10.1007/s10974-015-9423-3] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Accepted: 09/10/2015] [Indexed: 12/14/2022]
Abstract
We discuss here the potential mechanisms of action associated with hypertrophic (HCM) or dilated (DCM) cardiomyopathy causing mutations in the myosin regulatory (RLC) and essential (ELC) light chains. Specifically, we focus on four HCM mutations: RLC-A13T, RLC-K104E, ELC-A57G and ELC-M173V, and one DCM RLC-D94A mutation shown by population studies to cause different cardiomyopathy phenotypes in humans. Our studies indicate that RLC and ELC mutations lead to heart disease through different mechanisms with RLC mutations triggering alterations of the secondary structure of the RLC which further affect the structure and function of the lever arm domain and impose changes in the cross bridge cycling rates and myosin force generation ability. The ELC mutations exert their detrimental effects through changes in the interaction of the N-terminus of ELC with actin altering the cross talk between the thick and thin filaments and ultimately resulting in an altered force-pCa relationship. We also discuss the effect of mutations on myosin light chain phosphorylation. Exogenous myosin light chain phosphorylation and/or pseudo-phosphorylation were explored as potential rescue tools to treat hypertrophy-related cardiac phenotypes.
Collapse
Affiliation(s)
- Wenrui Huang
- 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.
| |
Collapse
|
19
|
Karabina A, Kazmierczak K, Szczesna-Cordary D, Moore JR. Myosin regulatory light chain phosphorylation enhances cardiac β-myosin in vitro motility under load. Arch Biochem Biophys 2015; 580:14-21. [PMID: 26116789 PMCID: PMC4790447 DOI: 10.1016/j.abb.2015.06.014] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2015] [Revised: 05/27/2015] [Accepted: 06/21/2015] [Indexed: 12/15/2022]
Abstract
Familial hypertrophic cardiomyopathy (HCM) is characterized by left ventricular hypertrophy and myofibrillar disarray, and often results in sudden cardiac death. Two HCM mutations, N47K and R58Q, are located in the myosin regulatory light chain (RLC). The RLC mechanically stabilizes the myosin lever arm, which is crucial to myosin's ability to transmit contractile force. The N47K and R58Q mutations have previously been shown to reduce actin filament velocity under load, stemming from a more compliant lever arm (Greenberg, 2010). In contrast, RLC phosphorylation was shown to impart stiffness to the myosin lever arm (Greenberg, 2009). We hypothesized that phosphorylation of the mutant HCM-RLC may mitigate distinct mutation-induced structural and functional abnormalities. In vitro motility assays were utilized to investigate the effects of RLC phosphorylation on the HCM-RLC mutant phenotype in the presence of an α-actinin frictional load. Porcine cardiac β-myosin was depleted of its native RLC and reconstituted with mutant or wild-type human RLC in phosphorylated or non-phosphorylated form. Consistent with previous findings, in the presence of load, myosin bearing the HCM mutations reduced actin sliding velocity compared to WT resulting in 31-41% reductions in force production. Myosin containing phosphorylated RLC (WT or mutant) increased sliding velocity and also restored mutant myosin force production to near WT unphosphorylated values. These results point to RLC phosphorylation as a general mechanism to increase force production of the individual myosin motor and as a potential target to ameliorate the HCM-induced phenotype at the molecular level.
Collapse
Affiliation(s)
- Anastasia Karabina
- Department of Physiology and Biophysics, Boston University School of Medicine, Boston, MA, USA
| | - Katarzyna Kazmierczak
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Danuta Szczesna-Cordary
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Jeffrey R Moore
- Department of Physiology and Biophysics, Boston University School of Medicine, Boston, MA, USA.
| |
Collapse
|
20
|
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.
Collapse
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
| |
Collapse
|
21
|
Valencia CA, Husami A, Holle J, Johnson JA, Qian Y, Mathur A, Wei C, Indugula SR, Zou F, Meng H, Wang L, Li X, Fisher R, Tan T, Hogart Begtrup A, Collins K, Wusik KA, Neilson D, Burrow T, Schorry E, Hopkin R, Keddache M, Harley JB, Kaufman KM, Zhang K. Clinical Impact and Cost-Effectiveness of Whole Exome Sequencing as a Diagnostic Tool: A Pediatric Center's Experience. Front Pediatr 2015; 3:67. [PMID: 26284228 PMCID: PMC4522872 DOI: 10.3389/fped.2015.00067] [Citation(s) in RCA: 135] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/13/2015] [Accepted: 07/13/2015] [Indexed: 11/17/2022] Open
Abstract
BACKGROUND There are limited reports of the use of whole exome sequencing (WES) as a clinical diagnostic tool. Moreover, there are no reports addressing the cost burden associated with genetic tests performed prior to WES. OBJECTIVE We demonstrate the performance characteristics of WES in a pediatric setting by describing our patient cohort, calculating the diagnostic yield, and detailing the patients for whom clinical management was altered. Moreover, we examined the potential cost-effectiveness of WES by examining the cost burden of diagnostic workups. METHODS To determine the clinical utility of our hospital's clinical WES, we performed a retrospective review of the first 40 cases. We utilized dual bioinformatics analyses pipelines based on commercially available software and in-house tools. RESULTS Of the first 40 clinical cases, we identified genetic defects in 12 (30%) patients, of which 47% of the mutations were previously unreported in the literature. Among the 12 patients with positive findings, seven have autosomal dominant disease and five have autosomal recessive disease. Ninety percent of the cohort opted to receive secondary findings and of those, secondary medical actionable results were returned in three cases. Among these positive cases, there are a number of novel mutations that are being reported here. The diagnostic workup included a significant number of genetic tests with microarray and single-gene sequencing being the most popular tests. Significantly, genetic diagnosis from WES led to altered patient medical management in positive cases. CONCLUSION We demonstrate the clinical utility of WES by establishing the clinical diagnostic rate and its impact on medical management in a large pediatric center. The cost-effectiveness of WES was demonstrated by ending the diagnostic odyssey in positive cases. Also, in some cases it may be most cost-effective to directly perform WES. WES provides a unique glimpse into the complexity of genetic disorders.
Collapse
Affiliation(s)
- C Alexander Valencia
- Division of Human Genetics, Cincinnati Children's Hospital Medical Center and Department of Pediatrics, University of Cincinnati College of Medicine , Cincinnati, OH , USA
| | - Ammar Husami
- Division of Human Genetics, Cincinnati Children's Hospital Medical Center and Department of Pediatrics, University of Cincinnati College of Medicine , Cincinnati, OH , USA
| | - Jennifer Holle
- Division of Human Genetics, Cincinnati Children's Hospital Medical Center and Department of Pediatrics, University of Cincinnati College of Medicine , Cincinnati, OH , USA
| | - Judith A Johnson
- Division of Human Genetics, Cincinnati Children's Hospital Medical Center and Department of Pediatrics, University of Cincinnati College of Medicine , Cincinnati, OH , USA
| | - Yaping Qian
- Myriad Genetics Laboratories, Inc. , Salt Lake City, UT , USA
| | - Abhinav Mathur
- Division of Human Genetics, Cincinnati Children's Hospital Medical Center and Department of Pediatrics, University of Cincinnati College of Medicine , Cincinnati, OH , USA
| | - Chao Wei
- Division of Human Genetics, Cincinnati Children's Hospital Medical Center and Department of Pediatrics, University of Cincinnati College of Medicine , Cincinnati, OH , USA
| | - Subba Rao Indugula
- Division of Human Genetics, Cincinnati Children's Hospital Medical Center and Department of Pediatrics, University of Cincinnati College of Medicine , Cincinnati, OH , USA
| | - Fanggeng Zou
- Division of Human Genetics, Cincinnati Children's Hospital Medical Center and Department of Pediatrics, University of Cincinnati College of Medicine , Cincinnati, OH , USA
| | - Haiying Meng
- Division of Human Genetics, Cincinnati Children's Hospital Medical Center and Department of Pediatrics, University of Cincinnati College of Medicine , Cincinnati, OH , USA
| | - Lijun Wang
- Division of Human Genetics, Cincinnati Children's Hospital Medical Center and Department of Pediatrics, University of Cincinnati College of Medicine , Cincinnati, OH , USA
| | - Xia Li
- Division of Human Genetics, Cincinnati Children's Hospital Medical Center and Department of Pediatrics, University of Cincinnati College of Medicine , Cincinnati, OH , USA
| | - Rachel Fisher
- Division of Human Genetics, Cincinnati Children's Hospital Medical Center and Department of Pediatrics, University of Cincinnati College of Medicine , Cincinnati, OH , USA
| | - Tony Tan
- Division of Human Genetics, Cincinnati Children's Hospital Medical Center and Department of Pediatrics, University of Cincinnati College of Medicine , Cincinnati, OH , USA
| | - Amber Hogart Begtrup
- Division of Human Genetics, Cincinnati Children's Hospital Medical Center and Department of Pediatrics, University of Cincinnati College of Medicine , Cincinnati, OH , USA
| | - Kathleen Collins
- Division of Human Genetics, Cincinnati Children's Hospital Medical Center and Department of Pediatrics, University of Cincinnati College of Medicine , Cincinnati, OH , USA
| | - Katie A Wusik
- Division of Human Genetics, Cincinnati Children's Hospital Medical Center and Department of Pediatrics, University of Cincinnati College of Medicine , Cincinnati, OH , USA
| | - Derek Neilson
- Division of Human Genetics, Cincinnati Children's Hospital Medical Center and Department of Pediatrics, University of Cincinnati College of Medicine , Cincinnati, OH , USA
| | - Thomas Burrow
- Division of Human Genetics, Cincinnati Children's Hospital Medical Center and Department of Pediatrics, University of Cincinnati College of Medicine , Cincinnati, OH , USA
| | - Elizabeth Schorry
- Division of Human Genetics, Cincinnati Children's Hospital Medical Center and Department of Pediatrics, University of Cincinnati College of Medicine , Cincinnati, OH , USA
| | - Robert Hopkin
- Division of Human Genetics, Cincinnati Children's Hospital Medical Center and Department of Pediatrics, University of Cincinnati College of Medicine , Cincinnati, OH , USA
| | - Mehdi Keddache
- Division of Human Genetics, Cincinnati Children's Hospital Medical Center and Department of Pediatrics, University of Cincinnati College of Medicine , Cincinnati, OH , USA
| | - John Barker Harley
- Center for Autoimmune Genomics and Etiology (CAGE), Cincinnati Children's Hospital Medical Center and Department of Pediatrics, University of Cincinnati College of Medicine , Cincinnati, OH , USA ; US Department of Veterans Affairs Medical Center , Cincinnati, OH , USA
| | - Kenneth M Kaufman
- Center for Autoimmune Genomics and Etiology (CAGE), Cincinnati Children's Hospital Medical Center and Department of Pediatrics, University of Cincinnati College of Medicine , Cincinnati, OH , USA ; US Department of Veterans Affairs Medical Center , Cincinnati, OH , USA
| | - Kejian Zhang
- Division of Human Genetics, Cincinnati Children's Hospital Medical Center and Department of Pediatrics, University of Cincinnati College of Medicine , Cincinnati, OH , USA
| |
Collapse
|
22
|
Huang W, Liang J, Kazmierczak K, Muthu P, Duggal D, Farman GP, Sorensen L, Pozios I, Abraham TP, Moore JR, Borejdo J, Szczesna-Cordary D. Hypertrophic cardiomyopathy associated Lys104Glu mutation in the myosin regulatory light chain causes diastolic disturbance in mice. J Mol Cell Cardiol 2014; 74:318-29. [PMID: 24992035 PMCID: PMC4115013 DOI: 10.1016/j.yjmcc.2014.06.011] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/27/2014] [Revised: 06/20/2014] [Accepted: 06/21/2014] [Indexed: 12/20/2022]
Abstract
We have examined, for the first time, the effects of the familial hypertrophic cardiomyopathy (HCM)-associated Lys104Glu mutation in the myosin regulatory light chain (RLC). Transgenic mice expressing the Lys104Glu substitution (Tg-MUT) were generated and the results were compared to Tg-WT (wild-type human ventricular RLC) mice. Echocardiography with pulse wave Doppler in 6month-old Tg-MUT showed early signs of diastolic disturbance with significantly reduced E/A transmitral velocities ratio. Invasive hemodynamics in 6month-old Tg-MUT mice also demonstrated a borderline significant prolonged isovolumic relaxation time (Tau) and a tendency for slower rate of pressure decline, suggesting alterations in diastolic function in Tg-MUT. Six month-old mutant animals had no LV hypertrophy; however, at >13months they displayed significant hypertrophy and fibrosis. In skinned papillary muscles from 5 to 6month-old mice a mutation induced reduction in maximal tension and slower muscle relaxation rates were observed. Mutated cross-bridges showed increased rates of binding to the thin filaments and a faster rate of the power stroke. In addition, ~2-fold lower level of RLC phosphorylation was observed in the mutant compared to Tg-WT. In line with the higher mitochondrial content seen in Tg-MUT hearts, the MUT-myosin ATPase activity was significantly higher than WT-myosin, indicating increased energy consumption. In the in vitro motility assay, MUT-myosin produced higher actin sliding velocity under zero load, but the velocity drastically decreased with applied load in the MUT vs. WT myosin. Our results suggest that diastolic disturbance (impaired muscle relaxation, lower E/A) and inefficiency of energy use (reduced contractile force and faster ATP consumption) may underlie the Lys104Glu-mediated HCM phenotype.
Collapse
Affiliation(s)
- Wenrui Huang
- University of Miami, Miller School of Medicine, Miami, FL 33136, United States
| | - Jingsheng Liang
- University of Miami, Miller School of Medicine, Miami, FL 33136, United States
| | | | - Priya Muthu
- University of Miami, Miller School of Medicine, Miami, FL 33136, United States
| | - Divya Duggal
- University of North Texas Health Science Center, Fort Worth, TX 76107, United States
| | - Gerrie P Farman
- Boston University School of Medicine, Boston, MA 02118, United States
| | - Lars Sorensen
- Johns Hopkins University School of Medicine, Baltimore, MD 21205, United States
| | - Iraklis Pozios
- Johns Hopkins University School of Medicine, Baltimore, MD 21205, United States
| | - Theodore P Abraham
- Johns Hopkins University School of Medicine, Baltimore, MD 21205, United States
| | - Jeffrey R Moore
- Boston University School of Medicine, Boston, MA 02118, United States
| | - Julian Borejdo
- University of North Texas Health Science Center, Fort Worth, TX 76107, United States
| | | |
Collapse
|
23
|
Freudenberg-Hua Y, Freudenberg J, Vacic V, Abhyankar A, Emde AK, Ben-Avraham D, Barzilai N, Oschwald D, Christen E, Koppel J, Greenwald B, Darnell RB, Germer S, Atzmon G, Davies P. Disease variants in genomes of 44 centenarians. Mol Genet Genomic Med 2014; 2:438-50. [PMID: 25333069 PMCID: PMC4190879 DOI: 10.1002/mgg3.86] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2014] [Revised: 04/29/2014] [Accepted: 04/29/2014] [Indexed: 12/14/2022] Open
Abstract
To identify previously reported disease mutations that are compatible with extraordinary longevity, we screened the coding regions of the genomes of 44 Ashkenazi Jewish centenarians. Individual genome sequences were generated with 30× coverage on the Illumina HiSeq 2000 and single-nucleotide variants were called with the genome analysis toolkit (GATK). We identified 130 coding variants that were annotated as “pathogenic” or “likely pathogenic” based on the ClinVar database and that are infrequent in the general population. These variants were previously reported to cause a wide range of degenerative, neoplastic, and cardiac diseases with autosomal dominant, autosomal recessive, and X-linked inheritance. Several of these variants are located in genes that harbor actionable incidental findings, according to the recommendations of the American College of Medical Genetics. In addition, we found risk variants for late-onset neurodegenerative diseases, such as the APOE ε4 allele that was even present in a homozygous state in one centenarian who did not develop Alzheimer's disease. Our data demonstrate that the incidental finding of certain reported disease variants in an individual genome may not preclude an extraordinarily long life. When the observed variants are encountered in the context of clinical sequencing, it is thus important to exercise caution in justifying clinical decisions. In genome sequences of 44 Ashkenazi centenarians, we identified many coding variants that were annotated as “pathogenic” or “likely pathogenic” based on the ClinVar database. Our data demonstrate that the incidental finding of certain reported disease variants in an individual genome may not preclude an extraordinarily long life. When the observed variants are encountered in the context of clinical sequencing, it is thus important to exercise caution in justifying clinical decisions.
Collapse
Affiliation(s)
- Yun Freudenberg-Hua
- The Litwin-Zucker Research Center for the Study of Alzheimer's Disease and Memory Disorders, The Feinstein Institute for Medical Research, North Shore-LIJ Manhasset, New York, 11030 ; Division of Geriatric Psychiatry, Zucker Hillside Hospital, North Shore-LIJ Glen Oaks, New York, 11040
| | - Jan Freudenberg
- Robert S. Boas Center for Genomics and Human Genetics, The Feinstein Institute for Medical Research, North Shore-LIJ Manhasset, New York, 11030
| | - Vladimir Vacic
- New York Genome Center 101 Avenue of the Americas, New York, New York, 10013
| | - Avinash Abhyankar
- New York Genome Center 101 Avenue of the Americas, New York, New York, 10013
| | - Anne-Katrin Emde
- New York Genome Center 101 Avenue of the Americas, New York, New York, 10013
| | - Danny Ben-Avraham
- Institute for Aging Research Departments of Medicine and Genetics, Albert Einstein College of Medicine 1300 Morris Park Avenue, Bronx, New York, 10461
| | - Nir Barzilai
- Institute for Aging Research Departments of Medicine and Genetics, Albert Einstein College of Medicine 1300 Morris Park Avenue, Bronx, New York, 10461
| | - Dayna Oschwald
- New York Genome Center 101 Avenue of the Americas, New York, New York, 10013
| | - Erika Christen
- The Litwin-Zucker Research Center for the Study of Alzheimer's Disease and Memory Disorders, The Feinstein Institute for Medical Research, North Shore-LIJ Manhasset, New York, 11030
| | - Jeremy Koppel
- The Litwin-Zucker Research Center for the Study of Alzheimer's Disease and Memory Disorders, The Feinstein Institute for Medical Research, North Shore-LIJ Manhasset, New York, 11030 ; Division of Geriatric Psychiatry, Zucker Hillside Hospital, North Shore-LIJ Glen Oaks, New York, 11040
| | - Blaine Greenwald
- Division of Geriatric Psychiatry, Zucker Hillside Hospital, North Shore-LIJ Glen Oaks, New York, 11040
| | - Robert B Darnell
- New York Genome Center 101 Avenue of the Americas, New York, New York, 10013 ; Department of Molecular Neuro-Oncology, Howard Hughes Medical Institute, The Rockefeller University 1230 York Avenue, New York, New York, 10065
| | - Soren Germer
- New York Genome Center 101 Avenue of the Americas, New York, New York, 10013
| | - Gil Atzmon
- Institute for Aging Research Departments of Medicine and Genetics, Albert Einstein College of Medicine 1300 Morris Park Avenue, Bronx, New York, 10461
| | - Peter Davies
- The Litwin-Zucker Research Center for the Study of Alzheimer's Disease and Memory Disorders, The Feinstein Institute for Medical Research, North Shore-LIJ Manhasset, New York, 11030
| |
Collapse
|
24
|
Sliwa K, Mayosi BM. Recent advances in the epidemiology, pathogenesis and prognosis of acute heart failure and cardiomyopathy in Africa. Heart 2013; 99:1317-22. [PMID: 23680887 DOI: 10.1136/heartjnl-2013-303592] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
This review addresses recent advances in the epidemiology, pathogenesis and prognosis of acute heart failure and cardiomyopathy based on research conducted in Africa. We searched Medline/PubMed for publications on acute decompensated heart failure and cardiomyopathy in Africa for the past 5 years (ie, 1 January 2008 to 31 December 2012). This was supplemented with personal communications with colleagues from Africa working in the field. A large prospective registry has shown that acute decompensated heart failure is caused by hypertension, cardiomyopathy and rheumatic heart disease in 90% of cases, a pattern that is in contrast with the dominance of coronary artery disease in North America and Europe. Furthermore, acute heart failure is a disease of the young with a mean age of 52 years, occurs equally in men and women, and is associated with high mortality at 6 months (∼18%), which is, however, similar to that observed in non-African heart failure registries, suggesting that heart failure has a dire prognosis globally, regardless of aetiology. The molecular genetics of dilated cardiomyopathy, hypertrophic cardiomyopathy and arrhythmogenic right ventricular cardiomyopathy in Africans is consistent with observations elsewhere in the world; the unique founder effects in the Afrikaner provide an opportunity for the study of genotype-phenotype correlations in large numbers of individuals with cardiomyopathy due to the same mutation. Advances in the understanding of the molecular mechanisms of peripartum cardiomyopathy have led to promising clinical trials of bromocriptine in the treatment of peripartum heart failure. The key challenges of management of heart failure are the urgent need to increase the use of proven treatments by physicians, and the control of hypertension in primary care and at the population level.
Collapse
Affiliation(s)
- Karen Sliwa
- Hatter Institute for Cardiovascular Research in Africa, Department of Medicine, Groote Schuur Hospital and University of Cape Town, Cape Town, South Africa
| | | |
Collapse
|
25
|
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: 35] [Impact Index Per Article: 3.2] [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.
Collapse
Affiliation(s)
- Marian A J Weterman
- Department of Genome Analysis k2-213, Academic Medical Centre Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
26
|
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.
Collapse
Affiliation(s)
- Priya Muthu
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | | | | | | |
Collapse
|
27
|
Moore JR, Leinwand L, Warshaw DM. Understanding cardiomyopathy phenotypes based on the functional impact of mutations in the myosin motor. Circ Res 2012; 111:375-85. [PMID: 22821910 DOI: 10.1161/circresaha.110.223842] [Citation(s) in RCA: 147] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Hypertrophic (HCM) and dilated (DCM) cardiomyopathies are inherited diseases with a high incidence of death due to electric abnormalities or outflow tract obstruction. In many of the families afflicted with either disease, causative mutations have been identified in various sarcomeric proteins. In this review, we focus on mutations in the cardiac muscle molecular motor, myosin, and its associated light chains. Despite the >300 identified mutations, there is still no clear understanding of how these mutations within the same myosin molecule can lead to the dramatically different clinical phenotypes associated with HCM and DCM. Localizing mutations within myosin's molecular structure provides insight into the potential consequence of these perturbations to key functional domains of the motor. Review of biochemical and biophysical data that characterize the functional capacities of these mutant myosins suggests that mutant myosins with enhanced contractility lead to HCM, whereas those displaying reduced contractility lead to DCM. With gain and loss of function potentially being the primary consequence of a specific mutation, how these functional changes trigger the hypertrophic response and lead to the distinct HCM and DCM phenotypes will be the future investigative challenge.
Collapse
Affiliation(s)
- Jeffrey R Moore
- Department of Physiology and Biophysics, Boston University School of Medicine, Boston, MA 02118, USA.
| | | | | |
Collapse
|
28
|
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: 136] [Impact Index Per Article: 11.3] [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.
Collapse
|
29
|
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.
Collapse
|
30
|
Abstract
Rapid advances in DNA sequencing promise to enable new diagnostics and individualized therapies. Achieving personalized medicine, however, will require extensive research on highly reidentifiable, integrated datasets of genomic and health information. To assist with this, participants in the Personal Genome Project choose to forgo privacy via our institutional review board- approved "open consent" process. The contribution of public data and samples facilitates both scientific discovery and standardization of methods. We present our findings after enrollment of more than 1,800 participants, including whole-genome sequencing of 10 pilot participant genomes (the PGP-10). We introduce the Genome-Environment-Trait Evidence (GET-Evidence) system. This tool automatically processes genomes and prioritizes both published and novel variants for interpretation. In the process of reviewing the presumed healthy PGP-10 genomes, we find numerous literature references implying serious disease. Although it is sometimes impossible to rule out a late-onset effect, stringent evidence requirements can address the high rate of incidental findings. To that end we develop a peer production system for recording and organizing variant evaluations according to standard evidence guidelines, creating a public forum for reaching consensus on interpretation of clinically relevant variants. Genome analysis becomes a two-step process: using a prioritized list to record variant evaluations, then automatically sorting reviewed variants using these annotations. Genome data, health and trait information, participant samples, and variant interpretations are all shared in the public domain-we invite others to review our results using our participant samples and contribute to our interpretations. We offer our public resource and methods to further personalized medical research.
Collapse
|
31
|
A novel Myosin essential light chain mutation causes hypertrophic cardiomyopathy with late onset and low expressivity. Biochem Res Int 2012; 2012:685108. [PMID: 22957257 PMCID: PMC3432877 DOI: 10.1155/2012/685108] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2011] [Accepted: 02/07/2012] [Indexed: 02/02/2023] Open
Abstract
Hypertrophic cardiomyopathy (HCM) is caused by mutations in genes encoding sarcomere proteins. Mutations in MYL3, encoding the essential light chain of myosin, are rare and have been associated with sudden death. Both recessive and dominant patterns of inheritance have been suggested. We studied a large family with a 38-year-old asymptomatic HCM-affected male referred because of a murmur. The patient had HCM with left ventricular hypertrophy (max WT 21 mm), a resting left ventricular outflow gradient of 36 mm Hg, and left atrial dilation (54 mm). Genotyping revealed heterozygosity for a novel missense mutation, p.V79I, in MYL3. The mutation was not found in 300 controls, and the patient had no mutations in 10 sarcomere genes. Cascade screening revealed a further nine heterozygote mutation carriers, three of whom had ECG and/or echocardiographic abnormalities but did not fulfil diagnostic criteria for HCM. The penetrance, if we consider this borderline HCM the phenotype of the p.V79I mutation, was 40%, but the mean age of the nonpenetrant mutation carriers is 15, while the mean age of the penetrant mutation carriers is 47. The mutation affects a conserved valine replacing it with a larger isoleucine residue in the region of contact between the light chain and the myosin lever arm. In conclusion, MYL3 mutations can present with low expressivity and late onset.
Collapse
|
32
|
Kazmierczak K, Muthu P, Huang W, Jones M, Wang Y, Szczesna-Cordary D. Myosin regulatory light chain mutation found in hypertrophic cardiomyopathy patients increases isometric force production in transgenic mice. Biochem J 2012; 442:95-103. [PMID: 22091967 PMCID: PMC6589164 DOI: 10.1042/bj20111145] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
FHC (familial hypertrophic cardiomyopathy) is a heritable form of cardiac hypertrophy caused by mutations in genes encoding sarcomeric proteins. The present study focuses on the A13T mutation in the human ventricular myosin RLC (regulatory light chain) that is associated with a rare FHC variant defined by mid-ventricular obstruction and septal hypertrophy. We generated heart-specific Tg (transgenic) mice with ~10% of human A13T-RLC mutant replacing the endogenous mouse cardiac RLC. Histopathological examinations of longitudinal heart sections from Tg-A13T mice showed enlarged interventricular septa and profound fibrotic lesions compared with Tg-WT (wild-type), expressing the human ventricular RLC, or non-Tg mice. Functional studies revealed an abnormal A13T mutation-induced increase in isometric force production, no change in the force-pCa relationship and a decreased Vmax of the acto-myosin ATPase. In addition, a fluorescence-based assay showed a 3-fold lower binding affinity of the recombinant A13T mutant for the RLC-depleted porcine myosin compared with WT-RLC. These results suggest that the A13T mutation triggers a hypertrophic response through changes in cardiac sarcomere organization and myosin cross-bridge function leading to abnormal remodelling of the heart. The significant functional changes observed, despite a low level of A13T mutant incorporation into myofilaments, suggest a 'poison-peptide' mechanism of disease.
Collapse
Affiliation(s)
- Katarzyna Kazmierczak
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL 33136, U.S.A
| | - Priya Muthu
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL 33136, U.S.A
| | - Wenrui Huang
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL 33136, U.S.A
| | - Michelle Jones
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL 33136, U.S.A
| | - Yingcai Wang
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL 33136, U.S.A
| | - Danuta Szczesna-Cordary
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL 33136, U.S.A
| |
Collapse
|
33
|
Capek P, Vondrasek J, Skvor J, Brdicka R. Hypertrophic cardiomyopathy: from mutation to functional analysis of defective protein. Croat Med J 2012; 52:384-91. [PMID: 21674835 PMCID: PMC3118724 DOI: 10.3325/cmj.2011.52.384] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Aim To analyze the genesis of hypertrophic cardiomyopathy on a large cohort of patients from molecular genetics point of view and perform the functional analysis of the 3D molecular model of defective myosin-7 protein in silico. Methods The study enrolled 153 patients with diagnosed hypertrophic cardiomyopathy from different parts of the Czech Republic. DNA samples were analyzed for mutations in exons 21 and 22 of the MYH7 gene, which have been associated with high mutation clustering. The 3D model of human myosin-7 was built using the x-ray structure of nucleotide-free scallop myosin S1 as the structural template. We performed de novo structure prediction of mutant and wild type peptides spanning the 769-788 amino acids region of the myosin-7 protein. Results The Arg870His and Asp778Val amino acid alterations were found in 2 unrelated patients with a severe form of hypertrophic cardiomyopathy. The Asp778Val variation was chosen for subsequent 3D molecular modeling in silico. The mutation of the Asp by Val not only changes the character of the interaction pattern with other amino acids or ions but Val, being a small hydrophobic amino acid, can also completely change the stability of the region. Conclusion Mutation location in the MYH7 gene and changes in amino acid composition may have a crucial negative impact on the outcome of the disease in patients with hypertrophic cardiomyopathy. In addition, a mutation that changes the charge of the amino acid is more likely to affect protein function than a conservative mutation.
Collapse
Affiliation(s)
- Pavel Capek
- Department of Anthropology and Human Genetics, Charles University, Prague, Czech Republic.
| | | | | | | |
Collapse
|
34
|
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.
Collapse
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
| |
Collapse
|
35
|
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.
Collapse
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.
| | | | | |
Collapse
|
36
|
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: 68] [Impact Index Per Article: 4.9] [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.
Collapse
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
| |
Collapse
|
37
|
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.
Collapse
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.
| | | | | | | |
Collapse
|
38
|
Xu Q, Dewey S, Nguyen S, Gomes AV. Malignant and benign mutations in familial cardiomyopathies: Insights into mutations linked to complex cardiovascular phenotypes. J Mol Cell Cardiol 2010; 48:899-909. [DOI: 10.1016/j.yjmcc.2010.03.005] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/13/2009] [Revised: 03/01/2010] [Accepted: 03/06/2010] [Indexed: 12/17/2022]
|
39
|
Mettikolla P, Calander N, Luchowski R, Gryczynski I, Gryczynski Z, Borejdo J. Kinetics of a single cross-bridge in familial hypertrophic cardiomyopathy heart muscle measured by reverse Kretschmann fluorescence. JOURNAL OF BIOMEDICAL OPTICS 2010; 15:017011. [PMID: 20210485 PMCID: PMC2847936 DOI: 10.1117/1.3324871] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2009] [Revised: 01/04/2010] [Accepted: 01/06/2010] [Indexed: 05/28/2023]
Abstract
Familial hypertrophic cardiomyopathy (FHC) is a serious heart disease that often leads to a sudden cardiac death of young athletes. It is believed that the alteration of the kinetics of interaction between actin and myosin causes FHC by making the heart to pump blood inefficiently. We set out to check this hypothesis ex vivo. During contraction of heart muscle, a myosin cross-bridge imparts periodic force impulses to actin. The impulses are analyzed by fluorescence correlation spectroscopy (FCS) of fluorescently labeled actin. To minimize observation volume and background fluorescence, we carry out FCS measurements in surface plasmon coupled emission mode in a reverse Kretschmann configuration. Fluorescence is a result of near-field coupling of fluorophores excited in the vicinity of the metal-coated surface of a coverslip with the surface plasmons propagating in the metal. Surface plasmons decouple on opposite sides of the metal film and emit in a directional manner as far-field p-polarized radiation. We show that the rate of changes of orientation is significantly faster in contracting cardiac myofibrils of transgenic mice than wild type. These results are consistent with the fact that mutated heart muscle myosin translates actin faster in in vitro motility assays.
Collapse
Affiliation(s)
- Prasad Mettikolla
- University of North Texas Health Science Center, Department of Molecular Biology and Immunology, Fort Worth, Texas 76107, USA
| | | | | | | | | | | |
Collapse
|
40
|
Muthu P, Mettikolla P, Calander N, Luchowski R, Gryczynski I, Gryczynski Z, Szczesna-Cordary D, Borejdo J. Single molecule kinetics in the familial hypertrophic cardiomyopathy D166V mutant mouse heart. J Mol Cell Cardiol 2009; 48:989-98. [PMID: 19914255 DOI: 10.1016/j.yjmcc.2009.11.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/22/2009] [Revised: 10/21/2009] [Accepted: 11/06/2009] [Indexed: 11/26/2022]
Abstract
One of the sarcomeric mutations associated with a malignant phenotype of familial hypertrophic cardiomyopathy (FHC) is the D166V point mutation in the ventricular myosin regulatory light chain (RLC) encoded by the MYL2 gene. In this report we show that the rates of myosin cross-bridge attachment and dissociation are significantly different in isometrically contracting cardiac myofibrils from right ventricles of transgenic (Tg)-D166V and Tg-WT mice. We have derived the myosin cross-bridge kinetic rates by tracking the orientation of a fluorescently labeled single actin molecule. Orientation (measured by polarized fluorescence) oscillated between two states, corresponding to the actin-bound and actin-free states of the myosin cross-bridge. The rate of cross-bridge attachment during isometric contraction decreased from 3 s(-1) in myofibrils from Tg-WT to 1.4 s(-1) in myofibrils from Tg-D166V. The rate of detachment decreased from 1.3 s(-1) (Tg-WT) to 1.2 s(-1) (Tg-D166V). We also showed that the level of RLC phosphorylation was largely decreased in Tg-D166V myofibrils compared to Tg-WT. Our findings suggest that alterations in the myosin cross-bridge kinetics brought about by the D166V mutation in RLC might be responsible for the compromised function of the mutated hearts and lead to their inability to efficiently pump blood.
Collapse
Affiliation(s)
- Priya Muthu
- Department of Molecular Biology and Immunology and Center for Commercialization of Fluorescence Technologies, University of North Texas, Health Science Center, 3500 Camp Bowie Blvd, Fort Worth, TX 76107, USA
| | | | | | | | | | | | | | | |
Collapse
|
41
|
Shimada E, Kinoshita M, Murata K. Expression of cardiac myosin light chain 2 during embryonic heart development in medaka fish, Oryzias latipes, and phylogenetic relationship with other myosin light chains. Dev Growth Differ 2009; 51:1-16. [PMID: 19128401 DOI: 10.1111/j.1440-169x.2008.01074.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Cardiac myosin light chain 2 (MLC-2) plays a key role in heart development, contraction, and embryo and adult heart maintenance. In some animals, defects in the function of cardiac MLC-2 cause hypertrophic cardiomyopathy. To illuminate the functions of cardiac MLC-2 in embryonic heart formation and contraction, and into the evolution of MLC-2, we characterized the expression and requirement for medaka cardiac MLC-2 gene in the developing heart. Medaka cardiac MLC-2 cDNA (mcmlc2) was isolated and its gene expression pattern was determined. The mcmlc2 was found to be expressed in the bilateral cardiac mesoderm, the formed heart tube, and in both the differentiated ventricle and atrium. Knockdown of mcmlc2 function caused severe cardiac disorders, including edema in the atrium and sinus venosus. Using phylogenetic analysis, we found that physiological variations in the MLC-2 molecules evolved due to amino acid changes in the Ca(2+) binding domain during molecular evolution. Our findings concerning the function and expression of mcmlc2 are nearly identical with those of other MLC-2 genes, and our phylogenetic analysis suggests that during evolution, the variations in physiological function within the MLC-2 gene family have arisen from a change in the amino acids in the Ca(2+) binding domain in the MLC-2 molecule.
Collapse
Affiliation(s)
- Eriko Shimada
- Department of Animal Science, University of California, Davis, Davis, California 95616, USA
| | | | | |
Collapse
|
42
|
Andersen PS, Havndrup O, Hougs L, Sørensen KM, Jensen M, Larsen LA, Hedley P, Thomsen ARB, Moolman-Smook J, Christiansen M, Bundgaard H. Diagnostic yield, interpretation, and clinical utility of mutation screening of sarcomere encoding genes in Danish hypertrophic cardiomyopathy patients and relatives. Hum Mutat 2009; 30:363-70. [PMID: 19035361 DOI: 10.1002/humu.20862] [Citation(s) in RCA: 100] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The American Heart Association (AHA) recommends family screening for hypertrophic cardiomyopathy (HCM). We assessed the outcome of family screening combining clinical evaluation and screening for sarcomere gene mutations in a cohort of 90 Danish HCM patients and their close relatives, in all 451 persons. Index patients were screened for mutations in all coding regions of 10 sarcomere genes (MYH7, MYL3, MYBPC3, TNNI3, TNNT2, TPM1, ACTC, CSRP3, TCAP, and TNNC1) and five exons of TTN. Relatives were screened for presence of minor or major diagnostic criteria for HCM and tracking of DNA variants was performed. In total, 297 adult relatives (>18 years) (51.2%) fulfilled one or more criteria for HCM. A total of 38 HCM-causing mutations were detected in 32 index patients. Six patients carried two disease-associated mutations. Twenty-two mutations have only been identified in the present cohort. The genetic diagnostic yield was almost twice as high in familial HCM (53%) vs. HCM of sporadic or unclear inheritance (19%). The yield was highest in families with an additional history of HCM-related clinical events. In relatives, 29.9% of mutation carriers did not fulfil any clinical diagnostic criterion, and in 37.5% of relatives without a mutation, one or more criteria was fulfilled. A total of 60% of family members had no mutation and could be reassured and further follow-up ceased. Genetic diagnosis may be established in approximately 40% of families with the highest yield in familial HCM with clinical events. Mutation-screening was superior to clinical investigation in identification of individuals not at increased risk, where follow-up is redundant, but should be offered in all families with relatives at risk for developing HCM.
Collapse
Affiliation(s)
- Paal Skytt Andersen
- Department of Clinical Biochemistry, Statens Serum Institute, Copenhagen, Denmark.
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
43
|
Abraham TP, Jones M, Kazmierczak K, Liang HY, Pinheiro AC, Wagg CS, Lopaschuk GD, Szczesna-Cordary D. Diastolic dysfunction in familial hypertrophic cardiomyopathy transgenic model mice. Cardiovasc Res 2009; 82:84-92. [PMID: 19150977 DOI: 10.1093/cvr/cvp016] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
AIMS Several mutations in the ventricular myosin regulatory light chain (RLC) were identified to cause familial hypertrophic cardiomyopathy (FHC). Based on our previous cellular findings showing delayed calcium transients in electrically stimulated intact papillary muscle fibres from transgenic Tg-R58Q and Tg-N47K mice and, in addition, prolonged force transients in Tg-R58Q fibres, we hypothesized that the malignant FHC phenotype associated with the R58Q mutation is most likely related to diastolic dysfunction. METHODS AND RESULTS Cardiac morphology and in vivo haemodynamics by echocardiography as well as cardiac function in isolated perfused working hearts were assessed in transgenic (Tg) mutant mice. The ATPase-pCa relationship was determined in myofibrils isolated from Tg mouse hearts. In addition, the effect of both mutations on RLC phosphorylation was examined in rapidly frozen ventricular samples from Tg mice. Significantly, decreased cardiac function was observed in isolated perfused working hearts from both Tg-R58Q and Tg-N47K mice. However, echocardiographic examination showed significant alterations in diastolic transmitral velocities and deceleration time only in Tg-R58Q myocardium. Likewise, changes in Ca(2+) sensitivity, cooperativity, and an elevated level of ATPase activity at low [Ca(2+)] were only observed in myofibrils from Tg-R58Q mice. In addition, the R58Q mutation and not the N47K led to reduced RLC phosphorylation in Tg ventricles. CONCLUSION Our results suggest that the N47K and R58Q mutations may act through similar mechanisms, leading to compensatory hypertrophy of the functionally compromised myocardium, but the malignant R58Q phenotype is most likely associated with more severe alterations in cardiac performance manifested as impaired relaxation and global diastolic dysfunction. At the molecular level, we suggest that by reducing the phosphorylation of RLC, the R58Q mutation decreases the kinetics of myosin cross-bridges, leading to an increased myofilament calcium sensitivity and to overall changes in intracellular Ca(2+) homeostasis.
Collapse
|
44
|
Kerrick WGL, Kazmierczak K, Xu Y, Wang Y, Szczesna-Cordary D. Malignant familial hypertrophic cardiomyopathy D166V mutation in the ventricular myosin regulatory light chain causes profound effects in skinned and intact papillary muscle fibers from transgenic mice. FASEB J 2008; 23:855-65. [PMID: 18987303 DOI: 10.1096/fj.08-118182] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Transgenic (Tg) mice expressing approximately 95% of the D166V (aspartic acid to valine) mutation in the ventricular myosin regulatory light chain (RLC) shown to cause a malignant familial hypertrophic cardiomyopathy (FHC) phenotype were generated, and the skinned and intact papillary muscle fibers from the Tg-D166V mice were examined using a Guth muscle research system. A large increase in the Ca(2+) sensitivity of force and ATPase (Delta pCa(50)>0.25) and a significant decrease in maximal force and ATPase were observed in skinned muscle fibers from Tg-D166V mice compared with control mice. The cross-bridge dissociation rate g was dramatically decreased, whereas the energy cost (ATPase/force) was slightly increased in Tg-D166V fibers compared with controls. The calculated average force per D166V cross-bridge was also reduced. Intact papillary muscle data demonstrated prolonged force transients with no change in calcium transients in Tg-D166V fibers compared with control fibers. Histopathological examination revealed fibrotic lesions in the hearts of the older D166V mice. Our results suggest that a charge effect of the D166V mutation and/or a mutation-dependent decrease in RLC phosphorylation could initiate the slower kinetics of the D166V cross-bridges and ultimately affect the regulation of cardiac muscle contraction. Profound cellular changes observed in Tg-D166V myocardium when placed in vivo could trigger a series of pathological responses and result in poor prognosis for D166V-positive patients.
Collapse
Affiliation(s)
- W Glenn L Kerrick
- Dept. of Physiology and Biophysics, University of Miami, Miller School of Medicine, Miami, FL 33101, USA
| | | | | | | | | |
Collapse
|
45
|
Buvoli M, Hamady M, Leinwand LA, Knight R. Bioinformatics assessment of beta-myosin mutations reveals myosin's high sensitivity to mutations. Trends Cardiovasc Med 2008; 18:141-9. [PMID: 18555187 DOI: 10.1016/j.tcm.2008.04.001] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/14/2008] [Revised: 04/01/2008] [Accepted: 04/04/2008] [Indexed: 01/12/2023]
Abstract
More than 200 mutations in the beta-myosin gene (MYH7) that cause clinically distinct cardiac and/or skeletal myopathies have been reported, but to date, no comprehensive statistical analysis of these mutations has been performed. As a part of this review, we developed a new interactive database and research tool called MyoMAPR (Myopathic Mutation Analysis Profiler and Repository). We report that the distribution of mutations along the beta-myosin gene is not homogeneous, and that myosin is a highly constrained molecule with an uncommon sensitivity to amino acid substitutions. Increasing knowledge of the characteristics of MH7 mutations may provide a valuable resource for scientists and clinicians studying diagnosis, risk stratification, and treatment of disease associated with these mutations.
Collapse
Affiliation(s)
- Massimo Buvoli
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO 80309, USA
| | | | | | | |
Collapse
|
46
|
Sung HJ, Ryang YS, Jang SW, Lee CW, Han KH, Ko J. Proteomic analysis of differential protein expression in atherosclerosis. Biomarkers 2008; 11:279-90. [PMID: 16760137 DOI: 10.1080/13547500500525458] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Although recent studies have shown that several pro-inflammatory proteins can be used as biomarkers for atherosclerosis, the mechanism of atherogenesis is unclear and little information is available regarding proteins involved in development of the disease. Atherosclerotic tissue samples were collected from patients in order to identify the proteins involved in atherogenesis. The protein expression profile of atherosclerosis patients was analysed using two-dimensional electrophoresis-based proteomics. Thirty-nine proteins were detected that were differentially expressed in the atherosclerotic aorta compared with the normal aorta. Twenty-seven of these proteins were identified in the MS-FIT database. They are involved in a number of biological processes, including calcium-mediated processes, migration of vascular smooth muscle cells, matrix metalloproteinase activation and regulation of pro-inflammatory cytokines. Confirmation of differential protein expression was performed by Western blot analysis. Potential applications of the results include the identification and characterization of signalling pathways involved in atherogenesis, and further exploration of the role of selected identified proteins in atherosclerosis.
Collapse
Affiliation(s)
- H J Sung
- School of Life Sciences and Biotechnology, Korea University, Seongbuk-gu, Seoul, South Korea
| | | | | | | | | | | |
Collapse
|
47
|
Greenberg MJ, Watt JD, Jones M, Kazmierczak K, Szczesna-Cordary D, Moore JR. Regulatory light chain mutations associated with cardiomyopathy affect myosin mechanics and kinetics. J Mol Cell Cardiol 2008; 46:108-15. [PMID: 18929571 DOI: 10.1016/j.yjmcc.2008.09.126] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/31/2008] [Revised: 09/04/2008] [Accepted: 09/08/2008] [Indexed: 10/21/2022]
Abstract
The myosin regulatory light chain (RLC) wraps around the alpha-helical neck region of myosin. This neck region has been proposed to act as a lever arm, amplifying small conformational changes in the myosin head to generate motion. The RLC serves an important structural role, supporting the myosin neck region and a modulatory role, tuning the kinetics of the actin myosin interaction. Given the importance of the RLC, it is not surprising that mutations of the RLC can lead to familial hypertrophic cardiomyopathy (FHC), the leading cause of sudden cardiac death in people under 30. Population studies identified two FHC mutations located near the cationic binding site of the RLC, R58Q and N47K. Although these mutations are close in sequence, they differ in clinical presentation and prognosis, with R58Q showing a more severe phenotype. We examined the molecular based changes in myosin that are responsible for the disease phenotype by purifying myosin from transgenic mouse hearts expressing mutant myosins and examining actin filament sliding using the in vitro motility assay. We found that both R58Q and N47K show reductions in force compared to the wild type that could result in compensatory hypertrophy. Furthermore, we observed a higher ATPase rate and an increased activation at submaximal calcium levels for the R58Q myosin that could lead to decreased efficiency and incomplete cardiac relaxation, potentially explaining the more severe phenotype for the R58Q mutation.
Collapse
Affiliation(s)
- Michael J Greenberg
- Department of Physiology and Biophysics, Boston University School of Medicine, Boston, MA 02118, USA
| | | | | | | | | | | |
Collapse
|
48
|
Thick and thin filament gene mutations in striated muscle diseases. Int J Mol Sci 2008; 9:1259-1275. [PMID: 19325803 PMCID: PMC2635722 DOI: 10.3390/ijms9071259] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2008] [Revised: 05/23/2008] [Accepted: 06/12/2008] [Indexed: 01/05/2023] Open
Abstract
The sarcomere is the fundamental unit of cardiac and skeletal muscle contraction. During the last ten years, there has been growing awareness of the etiology of skeletal and cardiac muscle diseases originating in the sarcomere, an important evolving field. Many sarcomeric diseases affect newborn children, i. e. are congenital myopathies. The discovery and characterization of several myopathies caused by mutations in myosin heavy chain genes, coding for the major component of skeletal muscle thick filaments, has led to the introduction of a new entity in the field of neuromuscular disorders: myosin myopathies. Recently, mutations in genes coding for skeletal muscle thin filaments, associated with various clinical features, have been identified. These mutations evoke distinct structural changes within the sarcomeric thin filament. Current knowledge regarding contractile protein dysfunction as it relates to disease pathogenesis has failed to decipher the mechanistic links between mutations identified in sarcomeric proteins and skeletal myopathies, which will no doubt require an integrated physiological approach. The discovery of additional genes associated with myopathies and the elucidation of the molecular mechanisms of pathogenesis will lead to improved and more accurate diagnosis, including prenatally, and to enhanced potential for prognosis, genetic counseling and developing possible treatments for these diseases. The goal of this review is to present recent progress in the identification of gene mutations from each of the major structural components of the sarcomere, the thick and thin filaments, related to skeletal muscle disease. The genetics and clinical manifestations of these disorders will be discussed.
Collapse
|
49
|
Szczesna-Cordary D, Jones M, Moore JR, Watt J, Kerrick WGL, Xu Y, Wang Y, Wagg C, Lopaschuk GD. Myosin regulatory light chain E22K mutation results in decreased cardiac intracellular calcium and force transients. FASEB J 2007; 21:3974-85. [PMID: 17606808 DOI: 10.1096/fj.07-8630com] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
The glutamic acid to lysine mutation at the 22nd amino acid residue (E22K) in the human cardiac myosin regulatory light chain (RLC) gene causes familial hypertrophic cardiomyopathy (FHC) with a phenotype of midventricular obstruction and septal hypertrophy. Our recent histopathology results have shown that the hearts of transgenic E22K mice (Tg-E22K) resemble those of human patients, demonstrating enlarged interventricular septa and papillary muscles. In this study, we show no effect of the E22K mutation on the kinetics of mutated myosin in its ATP-powered interaction with fluorescently labeled single actin filaments compared to nontransgenic or transgenic wild-type (Tg-WT) control mice. Likewise, no change in cross-bridge dissociation rates (g(app)) was observed in freshly skinned papillary muscle fibers. In contrast, maximal force and ATPase were decreased approximately 20% in Tg-E22K skinned papillary muscle fibers and intracellular [Ca2+] and force transients were significantly decreased in intact papillary muscle fibers from Tg-E22K compared to Tg-WT mice. Moreover, energy metabolism measured in isolated working Tg-E22K mouse hearts perfused under conditions of physiologically relevant levels of metabolic demand was similar in Tg-E22K and control hearts before and after 20 min of no-flow ischemia. Our results suggest that the pathological response observed in the E22K myocardium might be triggered by mutation induced changes in the properties of the RLC Ca2+-Mg2+ site, the state of the Ca2+/Mg2+ occupancy and consequently the Ca2+ buffering ability of the RLC. By decreasing the affinity of the RLC for Ca2+, the E22K mutation most likely promotes a Mg2+-saturated RLC producing less force and ATPase than the Ca2+-saturated RLC of WT fibers. Decreased Ca2+ binding may also lead to faster Ca2+ dissociation kinetics in Tg-E22K intact fibers resulting in decreased duration and amplitude of [Ca2+] and force transients. These changes when placed in vivo would result in higher workloads and consequently cardiac hypertrophy.
Collapse
Affiliation(s)
- Danuta Szczesna-Cordary
- University of Miami School of Medicine, Department of Molecular & Cellular Pharmacology (R-189), P.O. Box 016189, 1600 NW 10 Ave, Rm. 6113, Miami, FL 33101, USA.
| | | | | | | | | | | | | | | | | |
Collapse
|
50
|
Stelzer JE, Patel JR, Moss RL. Acceleration of stretch activation in murine myocardium due to phosphorylation of myosin regulatory light chain. ACTA ACUST UNITED AC 2006; 128:261-72. [PMID: 16908724 PMCID: PMC2151564 DOI: 10.1085/jgp.200609547] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The regulatory light chains (RLCs) of vertebrate muscle myosins bind to the neck region of the heavy chain domain and are thought to play important structural roles in force transmission between the cross-bridge head and thick filament backbone. In vertebrate striated muscles, the RLCs are reversibly phosphorylated by a specific myosin light chain kinase (MLCK), and while phosphorylation has been shown to accelerate the kinetics of force development in skeletal muscle, the effects of RLC phosphorylation in cardiac muscle are not well understood. Here, we assessed the effects of RLC phosphorylation on force, and the kinetics of force development in myocardium was isolated in the presence of 2,3-butanedione monoxime (BDM) to dephosphorylate RLC, subsequently skinned, and then treated with MLCK to phosphorylate RLC. Since RLC phosphorylation may be an important determinant of stretch activation in myocardium, we recorded the force responses of skinned myocardium to sudden stretches of 1% of muscle length both before and after treatment with MLCK. MLCK increased RLC phosphorylation, increased the Ca(2+) sensitivity of isometric force, reduced the steepness of the force-pCa relationship, and increased both Ca(2+)-activated and Ca(2+)-independent force. Sudden stretch of myocardium during an otherwise isometric contraction resulted in a concomitant increase in force that quickly decayed to a minimum and was followed by a delayed redevelopment of force, i.e., stretch activation, to levels greater than pre-stretch force. MLCK had profound effects on the stretch activation responses during maximal and submaximal activations: the amplitude and rate of force decay after stretch were significantly reduced, and the rate of delayed force recovery was accelerated and its amplitude reduced. These data show that RLC phosphorylation increases force and the rate of cross-bridge recruitment in murine myocardium, which would increase power generation in vivo and thereby enhance systolic function.
Collapse
Affiliation(s)
- Julian E Stelzer
- Department of Physiology, University of Wisconsin School of Medicine and Public Health, Madison, WI 53706, USA.
| | | | | |
Collapse
|