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Hu H, Geng Z, Zhang S, Xu Y, Wang Q, Chen S, Zhang B, Sun K, Lu Y. Rare copy number variation analysis identifies disease-related variants in atrioventricular septal defect patients. Front Genet 2023; 14:1075349. [PMID: 36816019 PMCID: PMC9936062 DOI: 10.3389/fgene.2023.1075349] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Accepted: 01/25/2023] [Indexed: 02/05/2023] Open
Abstract
Atrioventricular septal defect (AVSD) is a deleterious subtype of congenital heart diseases (CHD) characterized by atrioventricular canal defect. The pathogenic genetic changes of AVSD remain elusive, particularly for copy number variation (CNV), a large segment variation of the genome, which is one of the major forms of genetic variants resulting in congenital heart diseases. In the present study, we recruited 150 AVSD cases and 100 healthy subjects as controls for whole exome sequencing (WES). We identified total 4255 rare CNVs using exon Hidden Markov model (XHMM) and screened rare CNVs by eliminating common CNVs based on controls and Database of Genomic Variants (DGV). Each patient contained at least 9 CNVs, and the CNV burden was prominently presented in chromosomes 19,22,21&16. Small CNVs (<500 kb) were frequently observed. By leveraging gene-based burden test, we further identified 20 candidate AVSD-risk genes. Among them, DYRK1A, OBSCN and TTN were presented in the core disease network of CHD and highly and dynamically expressed in the heart during the development, which indicated they possessed the high potency to be AVSD-susceptible genes. These findings not only provided a roadmap for finally unveiling the genetic cause of AVSD, but also provided more resources and proofs for clinical genetics.
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Affiliation(s)
- Huan Hu
- Department of Pediatric Cardiology, Xin Hua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Zilong Geng
- Key Laboratory of Systems Biomedicine, Shanghai Center for Systems Biomedicine, Shanghai Jiao Tong University, Shanghai, China
| | - Shasha Zhang
- Key Laboratory of Systems Biomedicine, Shanghai Center for Systems Biomedicine, Shanghai Jiao Tong University, Shanghai, China
| | - Yuejuan Xu
- Department of Pediatric Cardiology, Xin Hua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Qingjie Wang
- Department of Pediatric Cardiology, Xin Hua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Sun Chen
- Department of Pediatric Cardiology, Xin Hua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Bing Zhang
- Key Laboratory of Systems Biomedicine, Shanghai Center for Systems Biomedicine, Shanghai Jiao Tong University, Shanghai, China,*Correspondence: Bing Zhang, ; Kun Sun, ; Yanan Lu,
| | - Kun Sun
- Department of Pediatric Cardiology, Xin Hua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China,*Correspondence: Bing Zhang, ; Kun Sun, ; Yanan Lu,
| | - Yanan Lu
- Department of Pediatric Cardiology, Xin Hua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China,*Correspondence: Bing Zhang, ; Kun Sun, ; Yanan Lu,
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2
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Noureddine M, Gehmlich K. Structural and signaling proteins in the Z-disk and their role in cardiomyopathies. Front Physiol 2023; 14:1143858. [PMID: 36935760 PMCID: PMC10017460 DOI: 10.3389/fphys.2023.1143858] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Accepted: 02/21/2023] [Indexed: 03/06/2023] Open
Abstract
The sarcomere is the smallest functional unit of muscle contraction. It is delineated by a protein-rich structure known as the Z-disk, alternating with M-bands. The Z-disk anchors the actin-rich thin filaments and plays a crucial role in maintaining the mechanical stability of the cardiac muscle. A multitude of proteins interact with each other at the Z-disk and they regulate the mechanical properties of the thin filaments. Over the past 2 decades, the role of the Z-disk in cardiac muscle contraction has been assessed widely, however, the impact of genetic variants in Z-disk proteins has still not been fully elucidated. This review discusses the various Z-disk proteins (alpha-actinin, filamin C, titin, muscle LIM protein, telethonin, myopalladin, nebulette, and nexilin) and Z-disk-associated proteins (desmin, and obscurin) and their role in cardiac structural stability and intracellular signaling. This review further explores how genetic variants of Z-disk proteins are linked to inherited cardiac conditions termed cardiomyopathies.
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Affiliation(s)
- Maya Noureddine
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
- *Correspondence: Maya Noureddine, ; Katja Gehmlich,
| | - Katja Gehmlich
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
- Cardiovascular Medicine, Radcliffe Department of Medicine and British Heart Foundation Centre of Research Excellence Oxford, University of Oxford, Oxford, United Kingdom
- *Correspondence: Maya Noureddine, ; Katja Gehmlich,
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A novel missense mutation in obscurin gene in a Chinese consanguineous family with left ventricular noncompaction. J Geriatr Cardiol 2022; 19:531-538. [PMID: 35975021 PMCID: PMC9361159 DOI: 10.11909/j.issn.1671-5411.2022.07.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
BACKGROUND Left ventricular noncompaction (LVNC) is an increasingly recognised cardiomyopathy of which a significant percentage are genetic in origin. The purpose of the present study was to identify potential pathogenic mutation leading to disease in a Chinese LVNC family. METHODS A 3-generation family affected by LVNC was recruited. Clinical assessments were performed on available family members, with clinical examination, ECG, echocardiography and cardiac MRI. The proband (I-2), the proband's daughter (II-1, affected) and mother (III-1, unaffected) were selected for WGS. Sanger sequencing were performed in all of the 4 surviving family members. RESULTS Combined whole genome sequencing with linkage analysis identified a novel missense mutation in the giant protein obscurin (OBSCN NM_001098623, c.C19063T), as the only plausible disease-causing variant that segregates with disease among the four surviving individuals, with interrogation of the entire genome excluding other potential causes. This c.C19063T missense mutation resulted in p.R6355W in the encoded OBSCN protein. It affected a highly conserved residue in the C terminus of the obscurin-B-like isoform between the PH and STKc domains, which was predicted to affect the function of the protein by different bioinformatics tools. CONCLUSIONS Here we present clinical and genetic evidence implicating the novel R6355W missense mutation in obscurin as the cause of familial LVNC. This expands the spectrum of obscurin's roles in cardiomyopathies. It furthermore highlights that rare obscurin missense variants, currently often ignored or left uninterpreted, should be considered to be relevant for cardiomyopathies and can be identified by the approach presented here. This study also provided new insights into the molecular basis of OBSCN mutation positive LVNC.
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Subramaniam J, Yamankurt G, Cunha SR. Obscurin regulates ankyrin macromolecular complex formation. J Mol Cell Cardiol 2022; 168:44-57. [PMID: 35447147 PMCID: PMC11057898 DOI: 10.1016/j.yjmcc.2022.04.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Revised: 03/28/2022] [Accepted: 04/12/2022] [Indexed: 10/18/2022]
Abstract
Obscurin is a large scaffolding protein in striated muscle that maintains sarcolemmal integrity and aligns the sarcoplasmic reticulum with the underlying contractile machinery. Ankyrins are a family of adaptor proteins with some isoforms that interact with obscurin. Previous studies have examined obscurin interacting with individual ankyrins. In this study, we demonstrate that two different ankyrins interact with obscurin's carboxyl terminus via independent ankyrin-binding domains (ABDs). Using in-vitro binding assays, co-precipitation assays, and FLIM-FRET analysis, we show that obscurin interacts with small ankyrin 1.5 (sAnk1.5) and the muscle-specific ankyrin-G isoform (AnkG107). While there is no direct interaction between sAnk1.5 and AnkG107, obscurin connects the two ankyrins both in vitro and in cells. Moreover, AnkG107 recruits β-spectrin to this macromolecular protein complex and mutating obscurin's ABDs disrupts complex formation. To further characterize AnkG107 interaction with obscurin, we measure obscurin-binding to different AnkG107 isoforms expressed in the heart and find that the first obscurin-binding domain in AnkG107 principally mediates this interaction. We also find that AnkG107 does not bind to filamin-C and displays minimal binding to plectin-1 compared to obscurin. Finally, both sAnk1.5-GFP and AnkG107-CTD-RFP are targeted to the M-lines of ventricular cardiomyocytes and mutating their obscurin-binding domains disrupts the M-line localization of these ankyrin constructs. Altogether, these findings support a model in which obscurin can interact via independent binding domains with two different ankyrin protein complexes to target them to the sarcomeric M-line of ventricular cardiomyocytes.
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Affiliation(s)
- Janani Subramaniam
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston, Houston, TX 77030, United States of America
| | - Gokay Yamankurt
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston, Houston, TX 77030, United States of America
| | - Shane R Cunha
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston, Houston, TX 77030, United States of America.
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Herrera-Rivero M, Gandhi S, Witten A, Ghalawinji A, Schotten U, Stoll M. Cardiac chamber-specific genetic alterations suggest candidate genes and pathways implicating the left ventricle in the pathogenesis of atrial fibrillation. Genomics 2022; 114:110320. [PMID: 35218871 DOI: 10.1016/j.ygeno.2022.110320] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Revised: 01/12/2022] [Accepted: 02/19/2022] [Indexed: 11/15/2022]
Abstract
It is believed that the atria play a predominant role in the initiation and maintenance of atrial fibrillation (AF), while the role of left ventricular dysfunction in the pathophysiology remains enigmatic. We sought to dissect chamber specificity of AF-associated transcriptional changes using RNA-sequencing. We performed intra- and inter-chamber differential expression analyses comparing AF against sinus rhythm to identify genes specifically dysregulated in human left atria, right atria, and left ventricle (LV), and integrated known AF genetic associations with expression quantitative trait loci datasets to inform the potential for disease causal contributions within each chamber. Inter-chamber patterns changed drastically. Vast AF-associated transcriptional changes specific to LV, enriched for biological pathway terms implicating mitochondrial function, developmental processes and immunity, were supported at the genetic level, but no major enrichments for candidate genes specific to the atria were found. Our observations suggest an active role of the LV in the pathogenesis of AF.
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Affiliation(s)
- Marisol Herrera-Rivero
- Department of Genetic Epidemiology, Institute of Human Genetics, University of Münster, Münster, Germany
| | - Shrey Gandhi
- Department of Genetic Epidemiology, Institute of Human Genetics, University of Münster, Münster, Germany; Institute for Evolution and Biodiversity, University of Münster, Münster, Germany
| | - Anika Witten
- Department of Genetic Epidemiology, Institute of Human Genetics, University of Münster, Münster, Germany
| | - Amer Ghalawinji
- Department of Genetic Epidemiology, Institute of Human Genetics, University of Münster, Münster, Germany
| | - Ulrich Schotten
- Department of Physiology, CARIM School for Cardiovascular Diseases, Maastricht University, Maastricht, the Netherlands
| | - Monika Stoll
- Department of Genetic Epidemiology, Institute of Human Genetics, University of Münster, Münster, Germany; Department of Biochemistry, Genetic Epidemiology and Statistical Genetics, CARIM School for Cardiovascular Diseases, Maastricht University, Maastricht, the Netherlands.
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Abstract
Inherited cardiomyopathies are a major cause of mortality and morbidity worldwide and can be caused by mutations in a wide range of proteins located in different cellular compartments. The present review is based on Dr. Ju Chen's 2021 Robert M. Berne Distinguished Lectureship of the American Physiological Society Cardiovascular Section, in which he provided an overview of the current knowledge on the cardiomyopathy-associated proteins that have been studied in his laboratory. The review provides a general summary of the proteins in different compartments of cardiomyocytes associated with cardiomyopathies, with specific focus on the proteins that have been studied in Dr. Chen's laboratory.
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Affiliation(s)
- Marie-Louise Bang
- 1Institute of Genetic and Biomedical Research (IRGB), National Research Council (CNR), Milan Unit, Milan, Italy,2IRCCS Humanitas Research Hospital, Rozzano (Milan), Italy
| | - Julius Bogomolovas
- 3Division of Cardiovascular Medicine, Department of Medicine Cardiology, University of California, San Diego, La Jolla, California
| | - Ju Chen
- 3Division of Cardiovascular Medicine, Department of Medicine Cardiology, University of California, San Diego, La Jolla, California
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Collyer J, Xu F, Munkhsaikhan U, Alberson NF, Orgil BO, Zhang W, Czosek RJ, Lu L, Jefferies JL, Towbin JA, Purevjav E. Combining whole exome sequencing with in silico analysis and clinical data to identify candidate variants in pediatric left ventricular noncompaction. Int J Cardiol 2022; 347:29-37. [PMID: 34752814 DOI: 10.1016/j.ijcard.2021.11.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 10/27/2021] [Accepted: 11/03/2021] [Indexed: 11/24/2022]
Abstract
BACKGROUND Understanding the overall variant burden in pediatric patients with left ventricular noncompaction (LVNC) has clinical implications. Whole exome sequencing (WES) allows detection of coding variants in both candidate cardiomyopathy genes and those included on commercial panels. Other lines of evidence, including in silico analysis, are necessary to reduce the overwhelming number of variants to those most likely having a phenotypic impact. METHODS Five families, including five pediatric probands with LVNC, 5 other affected, and 10 unaffected family members, had WES performed, followed by bioinformatics filtering and Sanger sequencing. Review of the HGMD, variant classification by ACMG guidelines, and clinical information were used to further refine complex genotypes. RESULTS One nonsense and eleven missense variants were identified. In Family 1, affected siblings carried digenic heterozygous variants: E1350K-MYH7 and A276V-ANKRD1. The proband also carried heterozygous W143X-NRG1. Four affected members of Family 2 carried K184Q-MYH7 while unaffected members did not. In Family 3, homozygous A161T-MYH7 and heterozygous P4935T-OBSCN variants were identified in the proband with the latter being absent in his unaffected brother. In Family 4, proband's father and half-sibling have mild hypertrabeculation and carry T3796I-PLEC. The proband, carrying T3796I-PLEC and V2878A-OBSCN, demonstrated higher trabeculation burden. The proband in Family 5 carried four variants, R3247W-PLEC, C92Y-ERG, T1233M-NCOR2, and E54K-HIST1H4B. Application of ACMG criteria and clinical data revealed that W143X-NRG1, P4935T-OBSCN, and V2878A-OBSCN likely have no phenotypic role. CONCLUSIONS We report nine variants, including novel T3796I-PLEC and biallelic A161T-MYH7, likely contributing to phenotypes ranging from asymptomatic hypertrabeculation to severe LVNC with heart failure.
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Affiliation(s)
- John Collyer
- Department of Pediatrics, University of Tennessee Health Science Center, Memphis, TN, United States of America; Children's Foundation Research Institute, Le Bonheur Children's Hospital, Memphis, TN, United States of America
| | - Fuyi Xu
- Department of Genetics, Genomics and Informatics, University of Tennessee Health Science Center, Memphis, TN, United States of America; School of Pharmacy, Binzhou Medical University, Yantai, Shandong 264003, China
| | - Undral Munkhsaikhan
- Department of Pediatrics, University of Tennessee Health Science Center, Memphis, TN, United States of America; Children's Foundation Research Institute, Le Bonheur Children's Hospital, Memphis, TN, United States of America
| | - Neely F Alberson
- Department of Pediatrics, University of Tennessee Health Science Center, Memphis, TN, United States of America; Children's Foundation Research Institute, Le Bonheur Children's Hospital, Memphis, TN, United States of America
| | - Buyan-Ochir Orgil
- Department of Pediatrics, University of Tennessee Health Science Center, Memphis, TN, United States of America; Children's Foundation Research Institute, Le Bonheur Children's Hospital, Memphis, TN, United States of America
| | - Wenying Zhang
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, United States of America; Laboratory of Genetics and Genomics, Division of Human Genetics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States of America
| | - Richard J Czosek
- Heart Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States of America
| | - Lu Lu
- Department of Genetics, Genomics and Informatics, University of Tennessee Health Science Center, Memphis, TN, United States of America
| | - John L Jefferies
- Division of Adult Cardiovascular Diseases, University of Tennessee Health Science Center, Memphis, TN, United States of America; Pediatric Cardiology, Le Bonheur Children's Hospital, Memphis, TN, United States of America; Pediatric Cardiology, St. Jude Children's Research Hospital, Memphis, TN, United States of America
| | - Jeffrey A Towbin
- Department of Pediatrics, University of Tennessee Health Science Center, Memphis, TN, United States of America; Pediatric Cardiology, Le Bonheur Children's Hospital, Memphis, TN, United States of America; Pediatric Cardiology, St. Jude Children's Research Hospital, Memphis, TN, United States of America
| | - Enkhsaikhan Purevjav
- Department of Pediatrics, University of Tennessee Health Science Center, Memphis, TN, United States of America; Children's Foundation Research Institute, Le Bonheur Children's Hospital, Memphis, TN, United States of America.
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8
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Lin Y, Huang J, Zhu Z, Zhang Z, Xian J, Yang Z, Qin T, Chen L, Huang J, Huang Y, Wu Q, Hu Z, Lin X, Xu G. Overlap phenotypes of the left ventricular noncompaction and hypertrophic cardiomyopathy with complex arrhythmias and heart failure induced by the novel truncated DSC2 mutation. Orphanet J Rare Dis 2021; 16:496. [PMID: 34819141 PMCID: PMC8611834 DOI: 10.1186/s13023-021-02112-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 11/06/2021] [Indexed: 12/18/2022] Open
Abstract
Background The left ventricular noncompaction cardiomyopathy (LVNC) is a rare subtype of cardiomyopathy associated with a high risk of heart failure (HF), thromboembolism, arrhythmia, and sudden cardiac death. Methods The proband with overlap phenotypes of LVNC and hypertrophic cardiomyopathy (HCM) complicates atrial fibrillation (AF), ventricular tachycardia (VT), and HF due to the diffuse myocardial lesion, which were diagnosed by electrocardiogram, echocardiogram and cardiac magnetic resonance imaging. Peripheral blood was collected from the proband and his relatives. DNA was extracted from the peripheral blood of proband for high-throughput target capture sequencing. The Sanger sequence verified the variants. The protein was extracted from the skin of the proband and healthy volunteer. The expression difference of desmocollin2 was detected by Western blot. Results The novel heterozygous truncated mutation (p.K47Rfs*2) of the DSC2 gene encoding an important component of desmosomes was detected by targeted capture sequencing. The western blots showed that the expressing level of functional desmocollin2 protein (~ 94kd) was lower in the proband than that in the healthy volunteer, indicating that DSC2 p.K47Rfs*2 obviously reduced the functional desmocollin2 protein expression in the proband. Conclusion The heterozygous DSC2 p.K47Rfs*2 remarkably and abnormally reduced the functional desmocollin2 expression, which may potentially induce the overlap phenotypes of LVNC and HCM, complicating AF, VT, and HF.
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Affiliation(s)
- Yubi Lin
- The Center of Cardiovascular Diseases, The Department of Cardiology, Radiology and Ultrasonography, Guangdong Provincial Key Laboratory of Biomedical Imaging, The Fifth Affiliated Hospital, Sun Yat-Sen University, Zhuhai, 519000, China
| | - Jiana Huang
- The Center of Cardiovascular Diseases, The Department of Cardiology, Radiology and Ultrasonography, Guangdong Provincial Key Laboratory of Biomedical Imaging, The Fifth Affiliated Hospital, Sun Yat-Sen University, Zhuhai, 519000, China.,Reproductive Center, The Six Affiliated Hospital, Sun Yat-Sen University, Guangzhou, 510000, China
| | - Zhiling Zhu
- The Center of Cardiovascular Diseases, The Department of Cardiology, Radiology and Ultrasonography, Guangdong Provincial Key Laboratory of Biomedical Imaging, The Fifth Affiliated Hospital, Sun Yat-Sen University, Zhuhai, 519000, China
| | - Zuoquan Zhang
- The Center of Cardiovascular Diseases, The Department of Cardiology, Radiology and Ultrasonography, Guangdong Provincial Key Laboratory of Biomedical Imaging, The Fifth Affiliated Hospital, Sun Yat-Sen University, Zhuhai, 519000, China
| | - Jianzhong Xian
- The Center of Cardiovascular Diseases, The Department of Cardiology, Radiology and Ultrasonography, Guangdong Provincial Key Laboratory of Biomedical Imaging, The Fifth Affiliated Hospital, Sun Yat-Sen University, Zhuhai, 519000, China
| | - Zhe Yang
- The Center of Cardiovascular Diseases, The Department of Cardiology, Radiology and Ultrasonography, Guangdong Provincial Key Laboratory of Biomedical Imaging, The Fifth Affiliated Hospital, Sun Yat-Sen University, Zhuhai, 519000, China
| | - Tingfeng Qin
- Department of Physiology, The School of Medicine of Jinan University, Guangzhou, 510000, China
| | - Linxi Chen
- Department of Physiology, The School of Medicine of Jinan University, Guangzhou, 510000, China
| | - Jingmin Huang
- Department of Physiology, The School of Medicine of Jinan University, Guangzhou, 510000, China
| | - Yin Huang
- The Center of Cardiovascular Diseases, The Department of Cardiology, Radiology and Ultrasonography, Guangdong Provincial Key Laboratory of Biomedical Imaging, The Fifth Affiliated Hospital, Sun Yat-Sen University, Zhuhai, 519000, China
| | - Qiaoyun Wu
- The Center of Cardiovascular Diseases, The Department of Cardiology, Radiology and Ultrasonography, Guangdong Provincial Key Laboratory of Biomedical Imaging, The Fifth Affiliated Hospital, Sun Yat-Sen University, Zhuhai, 519000, China
| | - Zhenyu Hu
- The Center of Cardiovascular Diseases, The Department of Cardiology, Radiology and Ultrasonography, Guangdong Provincial Key Laboratory of Biomedical Imaging, The Fifth Affiliated Hospital, Sun Yat-Sen University, Zhuhai, 519000, China.,Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 117593, Singapore
| | - Xiufang Lin
- The Center of Cardiovascular Diseases, The Department of Cardiology, Radiology and Ultrasonography, Guangdong Provincial Key Laboratory of Biomedical Imaging, The Fifth Affiliated Hospital, Sun Yat-Sen University, Zhuhai, 519000, China.
| | - Geyang Xu
- Department of Physiology, The School of Medicine of Jinan University, Guangzhou, 510000, China.
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Wu G, Liu J, Liu M, Huang Q, Ruan J, Zhang C, Wang D, Sun X, Jiang W, Kang L, Wang J, Song L. Truncating Variants in OBSCN Gene Associated With Disease-Onset and Outcomes of Hypertrophic Cardiomyopathy. CIRCULATION-GENOMIC AND PRECISION MEDICINE 2021; 14:e003401. [PMID: 34601892 DOI: 10.1161/circgen.121.003401] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND The presence of variants in OBSCN was identified to be linked to hypertrophic cardiomyopathy (HCM), but whether OBSCN truncating variants were associated with HCM remained unknown. METHODS Whole-exome sequencing was performed in 986 patients with HCM and 761 non-HCM controls to search for OBSCN truncating variants, and the result was tested in a replication cohort consisting of 529 patients with HCM and 307 controls. The association of the OBSCN truncating variants with baseline characteristics and prognosis of patients with HCM were ascertained. RESULTS There were 28 qualifying truncating variants in the OBSCN gene detected in 26 (2.6%) patients with HCM and 6 (0.8%) controls. The OBSCN truncating variants were more prevalent in patients with HCM than controls (odds ratio, 3.4, P=0.004). This association was confirmed in the replication cohort (odds ratio, 3.8, P=0.024). The combined effects of the two cohorts estimated the odds ratio to be 3.58 (P<0.001). Patients with or without OBSCN truncating variants shared similar demographic and echocardiographic variables at baseline. During 3.3±2.4 years (4795 patient-years) follow-up, the patients with OBSCN truncating variants were more likely to experience cardiovascular death (adjusted hazard ratio, 3.1 [95% CI, 1.40-6.70], P=0.005) and all-cause death (adjusted hazard ratio, 2.63 [95% CI, 1.21-5.71], P=0.015). CONCLUSIONS Our data indicated that OBSCN truncating variants contributed to the disease-onset of HCM, and increased the risk of malignant events in patients with HCM.
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Affiliation(s)
- Guixin Wu
- State Key Laboratory of Cardiovascular Disease (G.W., J.L., Q.H., J.R., C.Z., J.W., L.S.), Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.,Cardiomyopathy Ward (G.W., J.L., M.L., Q.H., J.R., D.W., X.S., W.J., L.K., L.S.), Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Jie Liu
- State Key Laboratory of Cardiovascular Disease (G.W., J.L., Q.H., J.R., C.Z., J.W., L.S.), Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.,Cardiomyopathy Ward (G.W., J.L., M.L., Q.H., J.R., D.W., X.S., W.J., L.K., L.S.), Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Minghao Liu
- Cardiomyopathy Ward (G.W., J.L., M.L., Q.H., J.R., D.W., X.S., W.J., L.K., L.S.), Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Qiya Huang
- State Key Laboratory of Cardiovascular Disease (G.W., J.L., Q.H., J.R., C.Z., J.W., L.S.), Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.,Cardiomyopathy Ward (G.W., J.L., M.L., Q.H., J.R., D.W., X.S., W.J., L.K., L.S.), Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Jieyun Ruan
- State Key Laboratory of Cardiovascular Disease (G.W., J.L., Q.H., J.R., C.Z., J.W., L.S.), Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.,Cardiomyopathy Ward (G.W., J.L., M.L., Q.H., J.R., D.W., X.S., W.J., L.K., L.S.), Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Channa Zhang
- State Key Laboratory of Cardiovascular Disease (G.W., J.L., Q.H., J.R., C.Z., J.W., L.S.), Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Dong Wang
- Cardiomyopathy Ward (G.W., J.L., M.L., Q.H., J.R., D.W., X.S., W.J., L.K., L.S.), Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Xiaolu Sun
- Cardiomyopathy Ward (G.W., J.L., M.L., Q.H., J.R., D.W., X.S., W.J., L.K., L.S.), Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Wen Jiang
- Cardiomyopathy Ward (G.W., J.L., M.L., Q.H., J.R., D.W., X.S., W.J., L.K., L.S.), Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Lianming Kang
- Cardiomyopathy Ward (G.W., J.L., M.L., Q.H., J.R., D.W., X.S., W.J., L.K., L.S.), Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Jizheng Wang
- State Key Laboratory of Cardiovascular Disease (G.W., J.L., Q.H., J.R., C.Z., J.W., L.S.), Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Lei Song
- State Key Laboratory of Cardiovascular Disease (G.W., J.L., Q.H., J.R., C.Z., J.W., L.S.), Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.,Cardiomyopathy Ward (G.W., J.L., M.L., Q.H., J.R., D.W., X.S., W.J., L.K., L.S.), Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.,National Clinical Research Center of Cardiovascular Diseases (L.S.), Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
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10
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Fukuzawa A, Koch D, Grover S, Rees M, Gautel M. When is an obscurin variant pathogenic? The impact of Arg4344Gln and Arg4444Trp variants on protein-protein interactions and protein stability. Hum Mol Genet 2021; 30:1131-1141. [PMID: 33438037 PMCID: PMC8188405 DOI: 10.1093/hmg/ddab010] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Revised: 12/17/2020] [Accepted: 01/04/2021] [Indexed: 11/13/2022] Open
Abstract
Obscurin is a giant muscle protein that connects the sarcomere with the sarcoplasmic reticulum, and has poorly understood structural and signalling functions. Increasingly, obscurin variants are implicated in the pathophysiology of cardiovascular diseases. The Arg4344Gln variant (R4344Q) in obscurin domain Ig58, initially discovered in a patient with hypertrophic cardiomyopathy, has been reported to reduce binding to titin domains Z8-Z9, impairing obscurin’s Z-disc localization. An R4344Q knock-in mouse developed a cardiomyopathy-like phenotype with abnormal Ca2+-handling and arrhythmias, which were attributed to an enhanced affinity of a putative interaction between obscurin Ig58 and phospholamban (PLN) due to the R4344Q variant. However, the R4344Q variant is found in 15% of African Americans, arguing against its pathogenicity. To resolve this apparent paradox, we quantified the influence of the R4344Q variant (alongside another potentially pathogenic variant: Arg4444Trp (R4444W)) on binding to titin Z8-Z9, novex-3 and PLN using pull-down assays and microscale thermophoresis and characterized the influence on domain stability using differential scanning fluorimetry. We found no changes in titin binding and thermostability for both variants and modestly increased affinities of PLN for R4344Q and R4444W. While we could not confirm the novex-3/obscurin interaction, the PLN/obscurin interaction relies on the transmembrane region of PLN and is not reproducible in mammalian cells, suggesting it is an in vitro artefact. Without clear clinical evidence for disease involvement, we advise against classifying these obscurin variants as pathogenic.
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Affiliation(s)
- Atsushi Fukuzawa
- Randall Centre for Cell & Molecular Biophysics, King's College London, 18-20 Newcomen Street, SE1 1UL, UK
| | - Daniel Koch
- Randall Centre for Cell & Molecular Biophysics, King's College London, 18-20 Newcomen Street, SE1 1UL, UK
| | - Sarah Grover
- Randall Centre for Cell & Molecular Biophysics, King's College London, 18-20 Newcomen Street, SE1 1UL, UK
| | - Martin Rees
- Randall Centre for Cell & Molecular Biophysics, King's College London, 18-20 Newcomen Street, SE1 1UL, UK
| | - Mathias Gautel
- Randall Centre for Cell & Molecular Biophysics, King's College London, 18-20 Newcomen Street, SE1 1UL, UK
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11
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T-tubule remodeling in human hypertrophic cardiomyopathy. J Muscle Res Cell Motil 2020; 42:305-322. [PMID: 33222034 PMCID: PMC8332592 DOI: 10.1007/s10974-020-09591-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Accepted: 10/22/2020] [Indexed: 11/17/2022]
Abstract
The highly organized transverse T-tubule membrane system represents the ultrastructural substrate for excitation–contraction coupling in ventricular myocytes. While the architecture and function of T-tubules have been well described in animal models, there is limited morpho-functional data on T-tubules in human myocardium. Hypertrophic cardiomyopathy (HCM) is a primary disease of the heart muscle, characterized by different clinical presentations at the various stages of its progression. Most HCM patients, indeed, show a compensated hypertrophic disease (“non-failing hypertrophic phase”), with preserved left ventricular function, and only a small subset of individuals evolves into heart failure (“end stage HCM”). In terms of T-tubule remodeling, the “end-stage” disease does not differ from other forms of heart failure. In this review we aim to recapitulate the main structural features of T-tubules during the “non-failing hypertrophic stage” of human HCM by revisiting data obtained from human myectomy samples. Moreover, by comparing pathological changes observed in myectomy samples with those introduced by acute (experimentally induced) detubulation, we discuss the role of T-tubular disruption as a part of the complex excitation–contraction coupling remodeling process that occurs during disease progression. Lastly, we highlight how T-tubule morpho-functional changes may be related to patient genotype and we discuss the possibility of a primitive remodeling of the T-tubule system in rare HCM forms associated with genes coding for proteins implicated in T-tubule structural integrity, formation and maintenance.
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12
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Finsterer J, Stöllberger C. Left Ventricular Noncompaction Syndrome: Genetic Insights and Therapeutic Perspectives. Curr Cardiol Rep 2020; 22:84. [DOI: 10.1007/s11886-020-01339-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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13
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Grogan A, Tsakiroglou P, Kontrogianni-Konstantopoulos A. Double the trouble: giant proteins with dual kinase activity in the heart. Biophys Rev 2020; 12:1019-1029. [PMID: 32638332 DOI: 10.1007/s12551-020-00715-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Accepted: 07/02/2020] [Indexed: 12/12/2022] Open
Abstract
Obscurin and its homolog, striated muscle preferentially expressed gene (SPEG), constitute a unique group of proteins abundantly expressed in striated muscles that contain two tandemly arranged MLCK-like kinases. The physiological significance of the dual kinase motifs is largely understudied; however, a collection of recent studies characterizing their binding interactions, putative targets, and disease-linked mutations have begun to shed light on their potential roles in muscle pathophysiology. Specifically, obscurin kinase 1 is proposed to regulate cardiomyocyte adhesion via phosphorylating N-cadherin, whereas SPEG kinases 1 and 2 regulate Ca2+ cycling by phosphorylating junctophilin-2 and the sarcoendoplasmic Ca2+ ATPase 2 (SERCA2). Herein, we review what is currently known regarding the potential substrates, physiological roles, and disease associations of obscurin and SPEG tandem kinase domains and provide future directions that have yet to be investigated.
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Affiliation(s)
- Alyssa Grogan
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, 108 N. Greene St, Baltimore, MD, 21201, USA
| | - Panagiotis Tsakiroglou
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, 108 N. Greene St, Baltimore, MD, 21201, USA
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Lange S, Pinotsis N, Agarkova I, Ehler E. The M-band: The underestimated part of the sarcomere. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2020; 1867:118440. [PMID: 30738787 PMCID: PMC7023976 DOI: 10.1016/j.bbamcr.2019.02.003] [Citation(s) in RCA: 50] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Revised: 01/16/2019] [Accepted: 02/05/2019] [Indexed: 12/20/2022]
Abstract
The sarcomere is the basic unit of the myofibrils, which mediate skeletal and cardiac Muscle contraction. Two transverse structures, the Z-disc and the M-band, anchor the thin (actin and associated proteins) and thick (myosin and associated proteins) filaments to the elastic filament system composed of titin. A plethora of proteins are known to be integral or associated proteins of the Z-disc and its structural and signalling role in muscle is better understood, while the molecular constituents of the M-band and its function are less well defined. Evidence discussed here suggests that the M-band is important for managing force imbalances during active muscle contraction. Its molecular composition is fine-tuned, especially as far as the structural linkers encoded by members of the myomesin family are concerned and depends on the specific mechanical characteristics of each particular muscle fibre type. Muscle activity signals from the M-band to the nucleus and affects transcription of sarcomeric genes, especially via serum response factor (SRF). Due to its important role as shock absorber in contracting muscle, the M-band is also more and more recognised as a contributor to muscle disease.
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Affiliation(s)
- Stephan Lange
- Biomedical Research Facility 2, School of Medicine, University of California, San Diego, Medical Sciences Research Bldg, 9500 Gilman Drive, La Jolla, CA 92093-0613C, USA; University of Gothenburg, Wallenberg Laboratory, Department of Molecular and Clinical Medicine, Institute of Medicine, Gothenburg, Sweden
| | - Nikos Pinotsis
- Institute of Structural and Molecular Biology, Department of Biological Sciences, Birkbeck College, Malet Street, London WC1E 7HX, UK
| | - Irina Agarkova
- InSphero, Wagistrasse 27, CH-8952 Schlieren, Switzerland
| | - Elisabeth Ehler
- Randall Centre for Cell and Molecular Biophysics, School of Basic and Medical Biosciences, King's College London, New Hunt's House, Guy's Campus, London SE1 1UL, UK; School of Cardiovascular Medicine and Sciences, British Heart Foundation Research Excellence Centre, King's College London, New Hunt's House, Guy's Campus, London SE1 1UL, UK.
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15
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Abela M, D’Silva A. Left Ventricular Trabeculations in Athletes: Epiphenomenon or Phenotype of Disease? CURRENT TREATMENT OPTIONS IN CARDIOVASCULAR MEDICINE 2018; 20:100. [PMID: 30367273 PMCID: PMC6209014 DOI: 10.1007/s11936-018-0698-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
PURPOSE OF REVIEW Excessive trabeculation attracting a diagnosis of left ventricular noncompaction cardiomyopathy (LVNC) has been reported in ostensibly healthy athletes. This review aims to explain why this occurs and whether this represents a spectrum of athletic physiological remodelling or unmasking of occult cardiomyopathy. RECENT FINDINGS Genetic studies have yet to identify a dominant mutation associated with the LVNC phenotype and reported gene mutations overlap with many distinct cardiomyopathies and ion channel disorders, implying that the phenotype is shared across different genetic conditions. Large contemporary cohort studies indicate that current LVNC imaging criteria are oversensitive and not predictive of adverse clinical outcomes. The majority of excessive LV trabeculation, as assessed by current quantification methods, is not due to cardiomyopathy but forms part of the normal continuum in health with potential contributions from cardiac remodelling processes. The study of rare, severe LVNC phenotypes may yield insights into an underlying molecular pathogenesis but in the absence of a universally accepted definition, contamination with aetiologically distinct conditions expressing a similar phenotype will remain an issue. Automated, objective quantification of trabeculation will help to define the normal distribution using big data without the constraint of wide interobserver variation.
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Affiliation(s)
- Mark Abela
- Cardiology Clinical Academic Group, St George’s, University of London, Cranmer Terrace, London, SW17 0RE UK
- MSc Sports Cardiology, Cardiology Clinical Academic Group, St George’s, University of London, London, UK
| | - Andrew D’Silva
- Cardiology Clinical Academic Group, St George’s, University of London, Cranmer Terrace, London, SW17 0RE UK
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16
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Grogan A, Kontrogianni-Konstantopoulos A. Unraveling obscurins in heart disease. Pflugers Arch 2018; 471:735-743. [PMID: 30099631 DOI: 10.1007/s00424-018-2191-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Accepted: 08/01/2018] [Indexed: 12/18/2022]
Abstract
Obscurins, expressed from the single OBSCN gene, are a family of giant, modular, cytoskeletal proteins that play key structural and regulatory roles in striated muscles. They were first implicated in the development of heart disease in 2007 when two missense mutations were found in a patient diagnosed with hypertrophic cardiomyopathy (HCM). Since then, the discovery of over a dozen missense, frameshift, and splicing mutations that are linked to various forms of cardiomyopathy, including HCM, dilated cardiomyopathy (DCM), and left ventricular non-compaction (LVNC), has highlighted OBSCN as a potential disease-causing gene. At this time, the functional consequences of the identified mutations remain largely elusive, and much work has yet to be done to characterize the disease mechanisms of pathological OBSCN variants. Herein, we describe the OBSCN mutations known to date, discuss their potential impact on disease development, and provide future directions in order to better understand the involvement of obscurins in heart disease.
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Affiliation(s)
- Alyssa Grogan
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, 108 N. Greene St., Baltimore, MD, 21201, USA
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17
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Wang L, Geist J, Grogan A, Hu LYR, Kontrogianni-Konstantopoulos A. Thick Filament Protein Network, Functions, and Disease Association. Compr Physiol 2018; 8:631-709. [PMID: 29687901 DOI: 10.1002/cphy.c170023] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Sarcomeres consist of highly ordered arrays of thick myosin and thin actin filaments along with accessory proteins. Thick filaments occupy the center of sarcomeres where they partially overlap with thin filaments. The sliding of thick filaments past thin filaments is a highly regulated process that occurs in an ATP-dependent manner driving muscle contraction. In addition to myosin that makes up the backbone of the thick filament, four other proteins which are intimately bound to the thick filament, myosin binding protein-C, titin, myomesin, and obscurin play important structural and regulatory roles. Consistent with this, mutations in the respective genes have been associated with idiopathic and congenital forms of skeletal and cardiac myopathies. In this review, we aim to summarize our current knowledge on the molecular structure, subcellular localization, interacting partners, function, modulation via posttranslational modifications, and disease involvement of these five major proteins that comprise the thick filament of striated muscle cells. © 2018 American Physiological Society. Compr Physiol 8:631-709, 2018.
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Affiliation(s)
- Li Wang
- Department of Biochemistry and Molecular Biology, University of Maryland, Baltimore, Maryland, USA
| | - Janelle Geist
- Department of Biochemistry and Molecular Biology, University of Maryland, Baltimore, Maryland, USA
| | - Alyssa Grogan
- Department of Biochemistry and Molecular Biology, University of Maryland, Baltimore, Maryland, USA
| | - Li-Yen R Hu
- Department of Biochemistry and Molecular Biology, University of Maryland, Baltimore, Maryland, USA
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18
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Begay RL, Graw SL, Sinagra G, Asimaki A, Rowland TJ, Slavov DB, Gowan K, Jones KL, Brun F, Merlo M, Miani D, Sweet M, Devaraj K, Wartchow EP, Gigli M, Puggia I, Salcedo EE, Garrity DM, Ambardekar AV, Buttrick P, Reece TB, Bristow MR, Saffitz JE, Mestroni L, Taylor MRG. Filamin C Truncation Mutations Are Associated With Arrhythmogenic Dilated Cardiomyopathy and Changes in the Cell-Cell Adhesion Structures. JACC Clin Electrophysiol 2018; 4:504-514. [PMID: 30067491 PMCID: PMC6074050 DOI: 10.1016/j.jacep.2017.12.003] [Citation(s) in RCA: 109] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Revised: 11/20/2017] [Accepted: 12/07/2017] [Indexed: 12/15/2022]
Abstract
OBJECTIVES The purpose of this study was to assess the phenotype of Filamin C (FLNC) truncating variants in dilated cardiomyopathy (DCM) and understand the mechanism leading to an arrhythmogenic phenotype. BACKGROUND Mutations in FLNC are known to lead to skeletal myopathies, which may have an associated cardiac component. Recently, the clinical spectrum of FLNC mutations has been recognized to include a cardiac-restricted presentation in the absence of skeletal muscle involvement. METHODS A population of 319 U.S. and European DCM cardiomyopathy families was evaluated using whole-exome and targeted next-generation sequencing. FLNC truncation probands were identified and evaluated by clinical examination, histology, transmission electron microscopy, and immunohistochemistry. RESULTS A total of 13 individuals in 7 families (2.2%) were found to harbor 6 different FLNC truncation variants (2 stopgain, 1 frameshift, and 3 splicing). Of the 13 FLNC truncation carriers, 11 (85%) had either ventricular arrhythmias or sudden cardiac death, and 5 (38%) presented with evidence of right ventricular dilation. Pathology analysis of 2 explanted hearts from affected FLNC truncation carriers showed interstitial fibrosis in the right ventricle and epicardial fibrofatty infiltration in the left ventricle. Ultrastructural findings included occasional disarray of Z-discs within the sarcomere. Immunohistochemistry showed normal plakoglobin signal at cell-cell junctions, but decreased signals for desmoplakin and synapse-associated protein 97 in the myocardium and buccal mucosa. CONCLUSIONS We found FLNC truncating variants, present in 2.2% of DCM families, to be associated with a cardiac-restricted arrhythmogenic DCM phenotype characterized by a high risk of life-threatening ventricular arrhythmias and a pathological cellular phenotype partially overlapping with arrhythmogenic right ventricular cardiomyopathy.
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Affiliation(s)
- Rene L Begay
- Cardiovascular Institute and Adult Medical Genetics Program, University of Colorado Denver, Aurora, Colorado
| | - Sharon L Graw
- Cardiovascular Institute and Adult Medical Genetics Program, University of Colorado Denver, Aurora, Colorado
| | - Gianfranco Sinagra
- Department of Cardiology, Ospedali Riuniti and University of Trieste, Trieste, Italy
| | - Angeliki Asimaki
- Department of Pathology, Beth Israel Deaconess Medical Center & Harvard Medical School, Boston, Massachusetts
| | - Teisha J Rowland
- Cardiovascular Institute and Adult Medical Genetics Program, University of Colorado Denver, Aurora, Colorado
| | - Dobromir B Slavov
- Cardiovascular Institute and Adult Medical Genetics Program, University of Colorado Denver, Aurora, Colorado
| | - Katherine Gowan
- Department of Pediatrics, Section of Hematology, Oncology, and Bone Marrow Transplant, University of Colorado Denver, Aurora, Colorado
| | - Kenneth L Jones
- Department of Pediatrics, Section of Hematology, Oncology, and Bone Marrow Transplant, University of Colorado Denver, Aurora, Colorado
| | - Francesca Brun
- Department of Cardiology, Ospedali Riuniti and University of Trieste, Trieste, Italy
| | - Marco Merlo
- Department of Cardiology, Ospedali Riuniti and University of Trieste, Trieste, Italy
| | - Daniela Miani
- Department of Cardiothoracic Science, University Hospital S. Maria della Misericordia, Udine, Italy
| | - Mary Sweet
- Cardiovascular Institute and Adult Medical Genetics Program, University of Colorado Denver, Aurora, Colorado
| | - Kalpana Devaraj
- Department of Pathology, University of Colorado, University Hospital, Aurora, Colorado
| | - Eric P Wartchow
- Department of Pathology, Children's Hospital Colorado, Aurora, Colorado
| | - Marta Gigli
- Department of Cardiology, Ospedali Riuniti and University of Trieste, Trieste, Italy
| | - Ilaria Puggia
- Department of Cardiology, Ospedali Riuniti and University of Trieste, Trieste, Italy
| | - Ernesto E Salcedo
- Cardiovascular Institute and Adult Medical Genetics Program, University of Colorado Denver, Aurora, Colorado
| | - Deborah M Garrity
- Center for Cardiovascular Research and Department of Biology, Colorado State University, Fort Collins, Colorado
| | - Amrut V Ambardekar
- Cardiovascular Institute and Adult Medical Genetics Program, University of Colorado Denver, Aurora, Colorado
| | - Peter Buttrick
- Cardiovascular Institute and Adult Medical Genetics Program, University of Colorado Denver, Aurora, Colorado
| | - T Brett Reece
- Department of Surgery, University of Colorado Denver, Aurora, Colorado
| | - Michael R Bristow
- Cardiovascular Institute and Adult Medical Genetics Program, University of Colorado Denver, Aurora, Colorado
| | - Jeffrey E Saffitz
- Department of Pathology, Beth Israel Deaconess Medical Center & Harvard Medical School, Boston, Massachusetts
| | - Luisa Mestroni
- Cardiovascular Institute and Adult Medical Genetics Program, University of Colorado Denver, Aurora, Colorado
| | - Matthew R G Taylor
- Cardiovascular Institute and Adult Medical Genetics Program, University of Colorado Denver, Aurora, Colorado.
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Abstract
Nonischemic dilated cardiomyopathy (DCM) often has a genetic pathogenesis. Because of the large number of genes and alleles attributed to DCM, comprehensive genetic testing encompasses ever-increasing gene panels. Genetic diagnosis can help predict prognosis, especially with regard to arrhythmia risk for certain subtypes. Moreover, cascade genetic testing in family members can identify those who are at risk or with early stage disease, offering the opportunity for early intervention. This review will address diagnosis and management of DCM, including the role of genetic evaluation. We will also overview distinct genetic pathways linked to DCM and their pathogenetic mechanisms. Historically, cardiac morphology has been used to classify cardiomyopathy subtypes. Determining genetic variants is emerging as an additional adjunct to help further refine subtypes of DCM, especially where arrhythmia risk is increased, and ultimately contribute to clinical management.
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Affiliation(s)
- Elizabeth M McNally
- From the Center for Genetic Medicine, Northwestern University Feinberg School of Medicine, Chicago IL (E.M.M.); and Cardiovascular Institute, University of Colorado Anschutz Medical Campus, Aurora (L.M.).
| | - Luisa Mestroni
- From the Center for Genetic Medicine, Northwestern University Feinberg School of Medicine, Chicago IL (E.M.M.); and Cardiovascular Institute, University of Colorado Anschutz Medical Campus, Aurora (L.M.).
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20
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Novel obscurins mediate cardiomyocyte adhesion and size via the PI3K/AKT/mTOR signaling pathway. J Mol Cell Cardiol 2017; 111:27-39. [PMID: 28826662 DOI: 10.1016/j.yjmcc.2017.08.004] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Revised: 08/02/2017] [Accepted: 08/03/2017] [Indexed: 12/29/2022]
Abstract
The intercalated disc of cardiac muscle embodies a highly-ordered, multifunctional network, essential for the synchronous contraction of the heart. Over 200 known proteins localize to the intercalated disc. The challenge now lies in their characterization as it relates to the coupling of neighboring cells and whole heart function. Using molecular, biochemical and imaging techniques, we characterized for the first time two small obscurin isoforms, obscurin-40 and obscurin-80, which are enriched at distinct locations of the intercalated disc. Both proteins bind specifically and directly to select phospholipids via their pleckstrin homology (PH) domain. Overexpression of either isoform or the PH-domain in cardiomyocytes results in decreased cell adhesion and size via reduced activation of the PI3K/AKT/mTOR pathway that is intimately linked to cardiac hypertrophy. In addition, obscurin-80 and obscurin-40 are significantly reduced in acute (myocardial infarction) and chronic (pressure overload) murine cardiac-stress models underscoring their key role in maintaining cardiac homeostasis. Our novel findings implicate small obscurins in the maintenance of cardiomyocyte size and coupling, and the development of heart failure by antagonizing the PI3K/AKT/mTOR pathway.
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21
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Randazzo D, Pierantozzi E, Rossi D, Sorrentino V. The potential of obscurin as a therapeutic target in muscle disorders. Expert Opin Ther Targets 2017; 21:897-910. [DOI: 10.1080/14728222.2017.1361931] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Davide Randazzo
- Light Imaging Section, Office of Science and Technology, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda
| | - Enrico Pierantozzi
- Molecular Medicine Section, Department of Molecular and Developmental Medicine, University of Siena, Siena, Italy
| | - Daniela Rossi
- Molecular Medicine Section, Department of Molecular and Developmental Medicine, University of Siena, Siena, Italy
| | - Vincenzo Sorrentino
- Molecular Medicine Section, Department of Molecular and Developmental Medicine, University of Siena, Siena, Italy
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22
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Forleo C, D’Erchia AM, Sorrentino S, Manzari C, Chiara M, Iacoviello M, Guaricci AI, De Santis D, Musci RL, La Spada A, Marangelli V, Pesole G, Favale S. Targeted next-generation sequencing detects novel gene-phenotype associations and expands the mutational spectrum in cardiomyopathies. PLoS One 2017; 12:e0181842. [PMID: 28750076 PMCID: PMC5531468 DOI: 10.1371/journal.pone.0181842] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2017] [Accepted: 07/08/2017] [Indexed: 12/19/2022] Open
Abstract
Cardiomyopathies are a heterogeneous group of primary diseases of the myocardium, including hypertrophic cardiomyopathy (HCM), dilated cardiomyopathy (DCM), and arrhythmogenic right ventricular cardiomyopathy (ARVC), with higher morbidity and mortality. These diseases are genetically diverse and associated with rare mutations in a large number of genes, many of which overlap among the phenotypes. To better investigate the genetic overlap between these three phenotypes and to identify new genotype–phenotype correlations, we designed a custom gene panel consisting of 115 genes known to be associated with cardiomyopathic phenotypes and channelopathies. A cohort of 38 unrelated patients, 16 affected by DCM, 14 by HCM and 8 by ARVC, was recruited for the study on the basis of more severe phenotypes and family history of cardiomyopathy and/or sudden death. We detected a total of 142 rare variants in 40 genes, and all patients were found to be carriers of at least one rare variant. Twenty-eight of the 142 rare variants were also predicted as potentially pathogenic variants and found in 26 patients. In 23 out of 38 patients, we found at least one novel potential gene–phenotype association. In particular, we detected three variants in OBSCN gene in ARVC patients, four variants in ANK2 gene and two variants in DLG1, TRPM4, and AKAP9 genes in DCM patients, two variants in PSEN2 gene and four variants in AKAP9 gene in HCM patients. Overall, our results confirmed that cardiomyopathic patients could carry multiple rare gene variants; in addition, our investigation of the genetic overlap among cardiomyopathies revealed new gene–phenotype associations. Furthermore, as our study confirms, data obtained using targeted next-generation sequencing could provide a remarkable contribution to the molecular diagnosis of cardiomyopathies, early identification of patients at risk for arrhythmia development, and better clinical management of cardiomyopathic patients.
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Affiliation(s)
- Cinzia Forleo
- Cardiology Unit, Department of Emergency and Organ Transplantation, University of Bari Aldo Moro, Bari, Italy
- * E-mail: (CF); (AMD)
| | - Anna Maria D’Erchia
- Department of Biosciences, Biotechnology and Biopharmaceutics, University of Bari Aldo Moro, Bari, Italy
- Institute of Biomembranes, Bioenergetics and Molecular Biotechnologies (IBIOM), National Research Council, Bari, Italy
- * E-mail: (CF); (AMD)
| | - Sandro Sorrentino
- Cardiology Unit, Department of Emergency and Organ Transplantation, University of Bari Aldo Moro, Bari, Italy
| | - Caterina Manzari
- Institute of Biomembranes, Bioenergetics and Molecular Biotechnologies (IBIOM), National Research Council, Bari, Italy
| | - Matteo Chiara
- Department of Biosciences, University of Milano, Milano, Italy
| | - Massimo Iacoviello
- Cardiology Unit, Department of Emergency and Organ Transplantation, University of Bari Aldo Moro, Bari, Italy
| | - Andrea Igoren Guaricci
- Cardiology Unit, Department of Emergency and Organ Transplantation, University of Bari Aldo Moro, Bari, Italy
| | - Delia De Santis
- Cardiology Unit, Department of Emergency and Organ Transplantation, University of Bari Aldo Moro, Bari, Italy
| | - Rita Leonarda Musci
- Cardiology Unit, Department of Emergency and Organ Transplantation, University of Bari Aldo Moro, Bari, Italy
| | - Antonino La Spada
- Cardiology Unit, Department of Emergency and Organ Transplantation, University of Bari Aldo Moro, Bari, Italy
| | - Vito Marangelli
- Cardiology Unit, Department of Emergency and Organ Transplantation, University of Bari Aldo Moro, Bari, Italy
| | - Graziano Pesole
- Department of Biosciences, Biotechnology and Biopharmaceutics, University of Bari Aldo Moro, Bari, Italy
- Institute of Biomembranes, Bioenergetics and Molecular Biotechnologies (IBIOM), National Research Council, Bari, Italy
| | - Stefano Favale
- Cardiology Unit, Department of Emergency and Organ Transplantation, University of Bari Aldo Moro, Bari, Italy
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Abstract
The inherited cardiomyopathies, hypertrophic cardiomyopathy (HCM), dilated cardiomyopathy (DCM) and left ventricular non-compaction (LVNC), have been frequently associated with mutations in sarcomeric proteins. In recent years, advances in DNA sequencing technology has allowed the study of the giant proteins of the sarcomere, such as titin and nebulin. Obscurin has been somewhat neglected in these studies, largely because its functional role is far from clear, although there was an isolated report in 2007 of obscurin mutations associated with HCM. Recently, whole exome sequencing methodology (WES) has been used to address mutations in OBSCN, the gene for obscurin, and OBSCN variants were found to be relatively common in inherited cardiomyopathies. In different studies, 5 OBSCN unique variants have been found in a group of 30 end-stage failing hearts, 6 OBSCN unique variants in 74 HCM cases and 3 OBSCN unique variants in 10 LVNC patients. As yet, the number of known potentially disease-causing OBSCN variants is quite small. The reason for this is that mutations in the OBSCN gene have not been recognised as potentially disease-causing until recently, and were not included in large-scale genetic surveys. OBSCN mutations may be causative of HCM, DCM and LVNC and other cardiomyopathies, or they may work in concert with other variants in the same or other genes to initiate the pathology. Currently, the function of obscurin is not well understood, but we anticipate that many more OBSCN variants linked to cardiomyopathy will be found when the large cohorts of patient sequences available are tested. It is to be hoped that the establishment of the importance of obscurin in pathology will stimulate a thorough investigation of obscurin function.
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Manring HR, Carter OA, Ackermann MA. Obscure functions: the location-function relationship of obscurins. Biophys Rev 2017; 9:245-258. [PMID: 28510116 DOI: 10.1007/s12551-017-0254-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2017] [Accepted: 03/05/2017] [Indexed: 12/18/2022] Open
Abstract
The obscurin family of polypeptides is essential for normal striated muscle function and contributes to the pathogenesis of fatal diseases, including cardiomyopathies and cancers. The single mammalian obscurin gene, OBSCN, gives rise to giant (∼800 kDa) and smaller (∼40-500 kDa) proteins that are composed of tandem adhesion and signaling motifs. Mammalian obscurin proteins are expressed in a variety of cell types, including striated muscles, and localize to distinct subcellular compartments where they contribute to diverse cellular processes. Obscurin homologs in Caenorhabditis elegans and Drosophila possess a similar domain architecture and are also expressed in striated muscles. The long sought after question, "what does obscurin do?" is complex and cannot be addressed without taking into consideration the subcellular distribution of these proteins and local isoform concentration. Herein, we present an overview of the functions of obscurins and begin to define the intricate relationship between their subcellular distributions and functions in striated muscles.
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Affiliation(s)
- Heather R Manring
- Department of Physiology and Cell Biology, The Ohio State University Wexner Medical Center, Ohio State University, Columbus, OH, 43210, USA.,Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Ohio State University, Columbus, OH, 43210, USA
| | - Olivia A Carter
- Department of Physiology and Cell Biology, The Ohio State University Wexner Medical Center, Ohio State University, Columbus, OH, 43210, USA.,Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Ohio State University, Columbus, OH, 43210, USA
| | - Maegen A Ackermann
- Department of Physiology and Cell Biology, The Ohio State University Wexner Medical Center, Ohio State University, Columbus, OH, 43210, USA. .,Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Ohio State University, Columbus, OH, 43210, USA.
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