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Sakamoto T, Kelly DP. Cardiac maturation. J Mol Cell Cardiol 2024; 187:38-50. [PMID: 38160640 PMCID: PMC10923079 DOI: 10.1016/j.yjmcc.2023.12.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Revised: 12/12/2023] [Accepted: 12/21/2023] [Indexed: 01/03/2024]
Abstract
The heart undergoes a dynamic maturation process following birth, in response to a wide range of stimuli, including both physiological and pathological cues. This process entails substantial re-programming of mitochondrial energy metabolism coincident with the emergence of specialized structural and contractile machinery to meet the demands of the adult heart. Many components of this program revert to a more "fetal" format during development of pathological cardiac hypertrophy and heart failure. In this review, emphasis is placed on recent progress in our understanding of the transcriptional control of cardiac maturation, encompassing the results of studies spanning from in vivo models to cardiomyocytes derived from human stem cells. The potential applications of this current state of knowledge to new translational avenues aimed at the treatment of heart failure is also addressed.
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Affiliation(s)
- Tomoya Sakamoto
- Cardiovascular Institute, Department of Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Daniel P Kelly
- Cardiovascular Institute, Department of Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA.
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2
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Vad OB, Angeli E, Liss M, Ahlberg G, Andreasen L, Christophersen IE, Hansen CC, Møller S, Hellsten Y, Haunsoe S, Tveit A, Svendsen JH, Gotthardt M, Lundegaard PR, Olesen MS. Loss of Cardiac Splicing Regulator RBM20 Is Associated With Early-Onset Atrial Fibrillation. JACC Basic Transl Sci 2024; 9:163-180. [PMID: 38510713 PMCID: PMC10950405 DOI: 10.1016/j.jacbts.2023.08.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Revised: 08/24/2023] [Accepted: 08/29/2023] [Indexed: 03/22/2024]
Abstract
We showed an association between atrial fibrillation and rare loss-of-function (LOF) variants in the cardiac splicing regulator RBM20 in 2 independent cohorts. In a rat model with loss of RBM20, we demonstrated altered splicing of sarcomere genes (NEXN, TTN, TPM1, MYOM1, and LDB3), and differential expression in key cardiac genes. We identified altered sarcomere and mitochondrial structure on electron microscopy imaging and found compromised mitochondrial function. Finally, we demonstrated that 3 novel LOF variants in RBM20, identified in patients with atrial fibrillation, lead to significantly reduced splicing activity. Our results implicate alternative splicing as a novel proarrhythmic mechanism in the atria.
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Affiliation(s)
- Oliver B. Vad
- Department of Cardiology, Copenhagen University Hospital–Rigshospitalet, Copenhagen, Denmark
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Elisavet Angeli
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Martin Liss
- Neuromuscular and Cardiovascular Cell Biology, Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany
| | - Gustav Ahlberg
- Department of Cardiology, Copenhagen University Hospital–Rigshospitalet, Copenhagen, Denmark
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Laura Andreasen
- Department of Cardiology, Copenhagen University Hospital–Rigshospitalet, Copenhagen, Denmark
| | - Ingrid E. Christophersen
- Department of Medical Research, Bærum Hospital, Vestre Viken Hospital Trust, Gjettum, Norway
- Department of Medical Genetics, Oslo University Hospital, Oslo, Norway
| | - Camilla C. Hansen
- The August Krogh Section for Human Physiology, Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
| | - Sophie Møller
- The August Krogh Section for Human Physiology, Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
| | - Ylva Hellsten
- The August Krogh Section for Human Physiology, Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
| | - Stig Haunsoe
- Department of Cardiology, Copenhagen University Hospital–Rigshospitalet, Copenhagen, Denmark
| | - Arnljot Tveit
- Department of Medical Research, Bærum Hospital, Vestre Viken Hospital Trust, Gjettum, Norway
- Institute of Clinical Medicine, Department of Cardiology, University of Oslo, Oslo, Norway
| | - Jesper H. Svendsen
- Department of Cardiology, Copenhagen University Hospital–Rigshospitalet, Copenhagen, Denmark
- Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
| | - Michael Gotthardt
- Neuromuscular and Cardiovascular Cell Biology, Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany
- Department of Cardiology, Charité Universitätsmedizin Berlin, Berlin, Germany
- German Center for Cardiovascular Research, partner site Berlin, Berlin, Germany
| | - Pia R. Lundegaard
- Department of Cardiology, Copenhagen University Hospital–Rigshospitalet, Copenhagen, Denmark
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Morten S. Olesen
- Department of Cardiology, Copenhagen University Hospital–Rigshospitalet, Copenhagen, Denmark
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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3
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Sun B, Kekenes-Huskey PM. Myofilament-associated proteins with intrinsic disorder (MAPIDs) and their resolution by computational modeling. Q Rev Biophys 2023; 56:e2. [PMID: 36628457 PMCID: PMC11070111 DOI: 10.1017/s003358352300001x] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The cardiac sarcomere is a cellular structure in the heart that enables muscle cells to contract. Dozens of proteins belong to the cardiac sarcomere, which work in tandem to generate force and adapt to demands on cardiac output. Intriguingly, the majority of these proteins have significant intrinsic disorder that contributes to their functions, yet the biophysics of these intrinsically disordered regions (IDRs) have been characterized in limited detail. In this review, we first enumerate these myofilament-associated proteins with intrinsic disorder (MAPIDs) and recent biophysical studies to characterize their IDRs. We secondly summarize the biophysics governing IDR properties and the state-of-the-art in computational tools toward MAPID identification and characterization of their conformation ensembles. We conclude with an overview of future computational approaches toward broadening the understanding of intrinsic disorder in the cardiac sarcomere.
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Affiliation(s)
- Bin Sun
- Research Center for Pharmacoinformatics (The State-Province Key Laboratories of Biomedicine-Pharmaceutics of China), Department of Medicinal Chemistry and Natural Medicine Chemistry, College of Pharmacy, Harbin Medical University, Harbin 150081, China
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4
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Ahmed RE, Tokuyama T, Anzai T, Chanthra N, Uosaki H. Sarcomere maturation: function acquisition, molecular mechanism, and interplay with other organelles. Philos Trans R Soc Lond B Biol Sci 2022; 377:20210325. [PMID: 36189811 PMCID: PMC9527934 DOI: 10.1098/rstb.2021.0325] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Accepted: 06/15/2022] [Indexed: 12/31/2022] Open
Abstract
During postnatal cardiac development, cardiomyocytes mature and turn into adult ones. Hence, all cellular properties, including morphology, structure, physiology and metabolism, are changed. One of the most important aspects is the contractile apparatus, of which the minimum unit is known as a sarcomere. Sarcomere maturation is evident by enhanced sarcomere alignment, ultrastructural organization and myofibrillar isoform switching. Any maturation process failure may result in cardiomyopathy. Sarcomere function is intricately related to other organelles, and the growing evidence suggests reciprocal regulation of sarcomere and mitochondria on their maturation. Herein, we summarize the molecular mechanism that regulates sarcomere maturation and the interplay between sarcomere and other organelles in cardiomyocyte maturation. This article is part of the theme issue 'The cardiomyocyte: new revelations on the interplay between architecture and function in growth, health, and disease'.
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Affiliation(s)
- Razan E. Ahmed
- Division of Regenerative Medicine, Center for Molecular Medicine, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke, Tochigi 329-0498, Japan
| | - Takeshi Tokuyama
- Division of Regenerative Medicine, Center for Molecular Medicine, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke, Tochigi 329-0498, Japan
| | - Tatsuya Anzai
- Division of Regenerative Medicine, Center for Molecular Medicine, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke, Tochigi 329-0498, Japan
- Department of Pediatrics, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke, Tochigi 329-0498, Japan
| | - Nawin Chanthra
- Division of Regenerative Medicine, Center for Molecular Medicine, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke, Tochigi 329-0498, Japan
| | - Hideki Uosaki
- Division of Regenerative Medicine, Center for Molecular Medicine, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke, Tochigi 329-0498, Japan
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5
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Astro V, Ramirez-Calderon G, Pennucci R, Caroli J, Saera-Vila A, Cardona-Londoño K, Forastieri C, Fiacco E, Maksoud F, Alowaysi M, Sogne E, Andrea Falqui, Gonzàlez F, Montserrat N, Battaglioli E, Andrea Mattevi, Adamo A. Fine-tuned KDM1A alternative splicing regulates human cardiomyogenesis through an enzymatic-independent mechanism. iScience 2022; 25:104665. [PMID: 35856020 PMCID: PMC9287196 DOI: 10.1016/j.isci.2022.104665] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Revised: 05/31/2022] [Accepted: 06/17/2022] [Indexed: 12/02/2022] Open
Abstract
The histone demethylase KDM1A is a multi-faceted regulator of vital developmental processes, including mesodermal and cardiac tube formation during gastrulation. However, it is unknown whether the fine-tuning of KDM1A splicing isoforms, already shown to regulate neuronal maturation, is crucial for the specification and maintenance of cell identity during cardiogenesis. Here, we discovered a temporal modulation of ubKDM1A and KDM1A+2a during human and mice fetal cardiac development and evaluated their impact on the regulation of cardiac differentiation. We revealed a severely impaired cardiac differentiation in KDM1A−/− hESCs that can be rescued by re-expressing ubKDM1A or catalytically impaired ubKDM1A-K661A, but not by KDM1A+2a or KDM1A+2a-K661A. Conversely, KDM1A+2a−/− hESCs give rise to functional cardiac cells, displaying increased beating amplitude and frequency and enhanced expression of critical cardiogenic markers. Our findings prove the existence of a divergent scaffolding role of KDM1A splice variants, independent of their enzymatic activity, during hESC differentiation into cardiac cells. ubKDM1A and KDM1A+2a isoforms are fine-tuned during fetal cardiac development Depletion of KDM1A isoforms impairs hESC differentiation into cardiac cells KDM1A+2a ablation enhances the expression of key cardiac markers KDM1A isoforms exhibit enzymatic-independent divergent roles during cardiogenesis
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Lamber EP, Guicheney P, Pinotsis N. The role of the M-band myomesin proteins in muscle integrity and cardiac disease. J Biomed Sci 2022; 29:18. [PMID: 35255917 PMCID: PMC8900313 DOI: 10.1186/s12929-022-00801-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Accepted: 02/28/2022] [Indexed: 11/30/2022] Open
Abstract
Transversal structural elements in cross-striated muscles, such as the M-band or the Z-disc, anchor and mechanically stabilize the contractile apparatus and its minimal unit—the sarcomere. The ability of proteins to target and interact with these structural sarcomeric elements is an inevitable necessity for the correct assembly and functionality of the myofibrillar apparatus. Specifically, the M-band is a well-recognized mechanical and signaling hub dealing with active forces during contraction, while impairment of its function leads to disease and death. Research on the M-band architecture is focusing on the assembly and interactions of the three major filamentous proteins in the region, mainly the three myomesin proteins including their embryonic heart (EH) isoform, titin and obscurin. These proteins form the basic filamentous network of the M-band, interacting with each other as also with additional proteins in the region that are involved in signaling, energetic or mechanosensitive processes. While myomesin-1, titin and obscurin are found in every muscle, the expression levels of myomesin-2 (also known as M-protein) and myomesin-3 are tissue specific: myomesin-2 is mainly expressed in the cardiac and fast skeletal muscles, while myomesin-3 is mainly expressed in intermediate muscles and specific regions of the cardiac muscle. Furthermore, EH-myomesin apart from its role during embryonic stages, is present in adults with specific cardiac diseases. The current work in structural, molecular, and cellular biology as well as in animal models, provides important details about the assembly of myomesin-1, obscurin and titin, the information however about the myomesin-2 and -3, such as their interactions, localization and structural details remain very limited. Remarkably, an increasing number of reports is linking all three myomesin proteins and particularly myomesin-2 to serious cardiovascular diseases suggesting that this protein family could be more important than originally thought. In this review we will focus on the myomesin protein family, the myomesin interactions and structural differences between isoforms and we will provide the most recent evidence why the structurally and biophysically unexplored myomesin-2 and myomesin-3 are emerging as hot targets for understanding muscle function and disease.
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Bang ML, Bogomolovas J, Chen J. Understanding the molecular basis of cardiomyopathy. Am J Physiol Heart Circ Physiol 2022; 322:H181-H233. [PMID: 34797172 PMCID: PMC8759964 DOI: 10.1152/ajpheart.00562.2021] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Revised: 11/16/2021] [Accepted: 11/16/2021] [Indexed: 02/03/2023]
Abstract
Inherited cardiomyopathies are a major cause of mortality and morbidity worldwide and can be caused by mutations in a wide range of proteins located in different cellular compartments. The present review is based on Dr. Ju Chen's 2021 Robert M. Berne Distinguished Lectureship of the American Physiological Society Cardiovascular Section, in which he provided an overview of the current knowledge on the cardiomyopathy-associated proteins that have been studied in his laboratory. The review provides a general summary of the proteins in different compartments of cardiomyocytes associated with cardiomyopathies, with specific focus on the proteins that have been studied in Dr. Chen's laboratory.
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Affiliation(s)
- Marie-Louise Bang
- Institute of Genetic and Biomedical Research (IRGB), National Research Council (CNR), Milan Unit, Milan, Italy
- IRCCS Humanitas Research Hospital, Rozzano (Milan), Italy
| | - Julius Bogomolovas
- Division of Cardiovascular Medicine, Department of Medicine Cardiology, University of California, San Diego, La Jolla, California
| | - Ju Chen
- Division of Cardiovascular Medicine, Department of Medicine Cardiology, University of California, San Diego, La Jolla, California
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Lv J, Pan Z, Chen J, Xu R, Wang D, Huang J, Dong Y, Jiang J, Yin X, Cheng H, Guo X. Phosphoproteomic Analysis Reveals Downstream PKA Effectors of AKAP Cypher/ZASP in the Pathogenesis of Dilated Cardiomyopathy. Front Cardiovasc Med 2021; 8:753072. [PMID: 34966794 PMCID: PMC8710605 DOI: 10.3389/fcvm.2021.753072] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Accepted: 11/08/2021] [Indexed: 11/13/2022] Open
Abstract
Background: Dilated cardiomyopathy (DCM) is a major cause of heart failure worldwide. The Z-line protein Cypher/Z-band alternatively spliced PDZ-motif protein (ZASP) is closely associated with DCM, both clinically and in animal models. Our earlier work revealed Cypher/ZASP as a PKA-anchoring protein (AKAP) that tethers PKA to phosphorylate target substrates. However, the downstream PKA effectors regulated by AKAP Cypher/ZASP and their relevance to DCM remain largely unknown.Methods and Results: For the identification of candidate PKA substrates, global quantitative phosphoproteomics was performed on cardiac tissue from wild-type and Cypher-knockout mice with PKA activation. A total of 216 phosphopeptides were differentially expressed in the Cypher-knockout mice; 31 phosphorylation sites were selected as candidates using the PKA consensus motifs. Bioinformatic analysis indicated that differentially expressed proteins were enriched mostly in cell adhesion and mRNA processing. Furthermore, the phosphorylation of β-catenin Ser675 was verified to be facilitated by Cypher. This phosphorylation promoted the transcriptional activity of β-catenin, and also the proliferative capacity of cardiomyocytes. Immunofluorescence staining demonstrated that Cypher colocalised with β-catenin in the intercalated discs (ICD) and altered the cytoplasmic distribution of β-catenin. Moreover, the phosphorylation of two other PKA substrates, vimentin Ser72 and troponin I Ser23/24, was suppressed by Cypher deletion.Conclusions: Cypher/ZASP plays an essential role in β-catenin activation via Ser675 phosphorylation, which modulates cardiomyocyte proliferation. Additionally, Cypher/ZASP regulates other PKA effectors, such as vimentin Ser72 and troponin I Ser23/24. These findings establish the AKAP Cypher/ZASP as a signalling hub in the progression of DCM.
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Affiliation(s)
- Jialan Lv
- Department of Cardiology, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Zhicheng Pan
- Department of Cardiology, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Jian Chen
- Department of Cardiology, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Rui Xu
- Department of Cardiology, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Dongfei Wang
- Department of Cardiology, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Jiaqi Huang
- Department of Physiology and Pathophysiology, Peking University Health Science Center, Beijing, China
| | - Yang Dong
- Department of Cardiology, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Jing Jiang
- Department of Cardiology, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Xiang Yin
- Department of Cardiology, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Hongqiang Cheng
- Department of Pathology and Pathophysiology, Zhejiang University School of Medicine, Hangzhou, China
- *Correspondence: Hongqiang Cheng
| | - Xiaogang Guo
- Department of Cardiology, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
- Xiaogang Guo
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Zhang X, Wang Z, Xu Q, Chen Y, Liu W, Zhong T, Li H, Quan C, Zhang L, Cui CP. Splicing factor Srsf5 deletion disrupts alternative splicing and causes noncompaction of ventricular myocardium. iScience 2021; 24:103097. [PMID: 34622152 PMCID: PMC8482499 DOI: 10.1016/j.isci.2021.103097] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Revised: 07/17/2021] [Accepted: 09/06/2021] [Indexed: 11/21/2022] Open
Abstract
The serine/arginine-rich (SR) family of splicing factors plays important roles in mRNA splicing activation, repression, export, stabilization, and translation. SR-splicing factor 5 (SRSF5) is a glucose-inducible protein that promotes tumor cell growth. However, the functional role of SRSF5 in tissue development and disease remains unknown. Here, Srsf5 knockout (Srsf5−/−) mice were generated using CRISPR-Cas9. Mutant mice were perinatally lethal and exhibited cardiac dysfunction with noncompaction of the ventricular myocardium. The left ventricular internal diameter and volume were increased in Srsf5−/− mice during systole. Null mice had abnormal electrocardiogram patterns, indicative of a light atrioventricular block. Mechanistically, Srsf5 promoted the alternative splicing of Myom1 (myomesin-1), a protein that crosslinks myosin filaments to the sarcomeric M-line. The switch between embryonic and adult isoforms of Myom1 could not be completed in Srsf5-deficient heart. These findings indicate that Srsf5-regulated alternative splicing plays a critical role during heart development. Systemic loss of Srsf5 causes perinatal lethality in mice Srsf5 deficiency leads to cardiac dysfunction Alternative splicing of Myom1 in the heart around birth is regulated by Srsf5
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Affiliation(s)
- Xiaoli Zhang
- The Key Laboratory of Pathobiology, Ministry of Education, College of Basic Medical Sciences, Jilin University, 126 Xinmin Avenue, Changchun, Jilin 130021, China.,State Key Laboratory of Proteomics, Beijing Proteome Research Center, National Center for Protein Sciences (Beijing), Beijing Institute of Lifeomics, 27 Taiping Road, Beijing 100850, China
| | - Ze Wang
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, National Center for Protein Sciences (Beijing), Beijing Institute of Lifeomics, 27 Taiping Road, Beijing 100850, China
| | - Qing Xu
- Core Facilities Centre, Capital Medical University, Beijing 100069, China
| | - Yuhan Chen
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, National Center for Protein Sciences (Beijing), Beijing Institute of Lifeomics, 27 Taiping Road, Beijing 100850, China
| | - Wen Liu
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, National Center for Protein Sciences (Beijing), Beijing Institute of Lifeomics, 27 Taiping Road, Beijing 100850, China
| | - Tong Zhong
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, National Center for Protein Sciences (Beijing), Beijing Institute of Lifeomics, 27 Taiping Road, Beijing 100850, China
| | - Hongchang Li
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, National Center for Protein Sciences (Beijing), Beijing Institute of Lifeomics, 27 Taiping Road, Beijing 100850, China
| | - Chengshi Quan
- The Key Laboratory of Pathobiology, Ministry of Education, College of Basic Medical Sciences, Jilin University, 126 Xinmin Avenue, Changchun, Jilin 130021, China
| | - Lingqiang Zhang
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, National Center for Protein Sciences (Beijing), Beijing Institute of Lifeomics, 27 Taiping Road, Beijing 100850, China
| | - Chun-Ping Cui
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, National Center for Protein Sciences (Beijing), Beijing Institute of Lifeomics, 27 Taiping Road, Beijing 100850, China
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Hang C, Song Y, Li Y, Zhang S, Chang Y, Bai R, Saleem A, Jiang M, Lu W, Lan F, Cui M. Knockout of MYOM1 in human cardiomyocytes leads to myocardial atrophy via impairing calcium homeostasis. J Cell Mol Med 2021; 25:1661-1676. [PMID: 33452765 PMCID: PMC7875908 DOI: 10.1111/jcmm.16268] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Revised: 12/14/2020] [Accepted: 12/22/2020] [Indexed: 12/27/2022] Open
Abstract
Myomesin-1 (encoded by MYOM1 gene) is expressed in almost all cross-striated muscles, whose family (together with myomesin-2 and myomesin-3) helps to cross-link adjacent myosin to form the M-line in myofibrils. However, little is known about its biological function, causal relationship and mechanisms underlying the MYOM1-related myopathies (especially in the heart). Regrettably, there is no MYMO1 knockout model for its study so far. A better and further understanding of MYOM1 biology is urgently needed. Here, we used CRISPR/Cas9 gene-editing technology to establish an MYOM1 knockout human embryonic stem cell line (MYOM1-/- hESC), which was then differentiated into myomesin-1 deficient cardiomyocytes (MYOM1-/- hESC-CMs) in vitro. We found that myomesin-1 plays an important role in sarcomere assembly, contractility regulation and cardiomyocytes development. Moreover, myomesin-1-deficient hESC-CMs can recapitulate myocardial atrophy phenotype in vitro. Based on this model, not only the biological function of MYOM1, but also the aetiology, pathogenesis, and potential treatments of myocardial atrophy caused by myomesin-1 deficiency can be studied.
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Affiliation(s)
- Chengwen Hang
- Department of CardiologyPeking University Third HospitalBeijingChina
| | - Yuanxiu Song
- Department of CardiologyPeking University Third HospitalBeijingChina
| | - Ya’nan Li
- Beijing Lab for Cardiovascular Precision MedicineAnzhen HospitalCapital Medical UniversityBeijingChina
| | - Siyao Zhang
- Beijing Lab for Cardiovascular Precision MedicineAnzhen HospitalCapital Medical UniversityBeijingChina
| | - Yun Chang
- Beijing Lab for Cardiovascular Precision MedicineAnzhen HospitalCapital Medical UniversityBeijingChina
| | - Rui Bai
- Beijing Lab for Cardiovascular Precision MedicineAnzhen HospitalCapital Medical UniversityBeijingChina
| | - Amina Saleem
- Beijing Lab for Cardiovascular Precision MedicineAnzhen HospitalCapital Medical UniversityBeijingChina
| | - Mengqi Jiang
- Department of CardiologyPeking University Third HospitalBeijingChina
| | - Wenjing Lu
- Beijing Lab for Cardiovascular Precision MedicineAnzhen HospitalCapital Medical UniversityBeijingChina
| | - Feng Lan
- Beijing Lab for Cardiovascular Precision MedicineAnzhen HospitalCapital Medical UniversityBeijingChina
| | - Ming Cui
- Department of CardiologyPeking University Third HospitalBeijingChina
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11
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Auxerre-Plantié E, Nielsen T, Grunert M, Olejniczak O, Perrot A, Özcelik C, Harries D, Matinmehr F, Dos Remedios C, Mühlfeld C, Kraft T, Bodmer R, Vogler G, Sperling SR. Identification of MYOM2 as a candidate gene in hypertrophic cardiomyopathy and Tetralogy of Fallot, and its functional evaluation in the Drosophila heart. Dis Model Mech 2020; 13:dmm045377. [PMID: 33033063 PMCID: PMC7758640 DOI: 10.1242/dmm.045377] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Accepted: 10/01/2020] [Indexed: 01/11/2023] Open
Abstract
The causal genetic underpinnings of congenital heart diseases, which are often complex and multigenic, are still far from understood. Moreover, there are also predominantly monogenic heart defects, such as cardiomyopathies, with known disease genes for the majority of cases. In this study, we identified mutations in myomesin 2 (MYOM2) in patients with Tetralogy of Fallot (TOF), the most common cyanotic heart malformation, as well as in patients with hypertrophic cardiomyopathy (HCM), who do not exhibit any mutations in the known disease genes. MYOM2 is a major component of the myofibrillar M-band of the sarcomere, and a hub gene within interactions of sarcomere genes. We show that patient-derived cardiomyocytes exhibit myofibrillar disarray and reduced passive force with increasing sarcomere lengths. Moreover, our comprehensive functional analyses in the Drosophila animal model reveal that the so far uncharacterized fly gene CG14964 [herein referred to as Drosophila myomesin and myosin binding protein (dMnM)] may be an ortholog of MYOM2, as well as other myosin binding proteins. Its partial loss of function or moderate cardiac knockdown results in cardiac dilation, whereas more severely reduced function causes a constricted phenotype and an increase in sarcomere myosin protein. Moreover, compound heterozygous combinations of CG14964 and the sarcomere gene Mhc (MYH6/7) exhibited synergistic genetic interactions. In summary, our results suggest that MYOM2 not only plays a critical role in maintaining robust heart function but may also be a candidate gene for heart diseases such as HCM and TOF, as it is clearly involved in the development of the heart.This article has an associated First Person interview with Emilie Auxerre-Plantié and Tanja Nielsen, joint first authors of the paper.
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Affiliation(s)
- Emilie Auxerre-Plantié
- Cardiovascular Genetics, Charité - Universitätsmedizin Berlin, 13125 Berlin, Germany
- Berlin Institute of Health (BIH), Berlin, Germany
| | - Tanja Nielsen
- Cardiovascular Genetics, Charité - Universitätsmedizin Berlin, 13125 Berlin, Germany
- Berlin Institute of Health (BIH), Berlin, Germany
- DZHK (German Centre for Cardiovascular Research), partner site Berlin, Berlin, Germany
- Development, Aging and Regeneration Program, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA 92037, USA
- Department of Biology, Chemistry, and Pharmacy, Freie Universität Berlin, 14195 Berlin, Germany
| | - Marcel Grunert
- Cardiovascular Genetics, Charité - Universitätsmedizin Berlin, 13125 Berlin, Germany
- Berlin Institute of Health (BIH), Berlin, Germany
- DZHK (German Centre for Cardiovascular Research), partner site Berlin, Berlin, Germany
| | - Olga Olejniczak
- Cardiovascular Genetics, Charité - Universitätsmedizin Berlin, 13125 Berlin, Germany
- Berlin Institute of Health (BIH), Berlin, Germany
- DZHK (German Centre for Cardiovascular Research), partner site Berlin, Berlin, Germany
- Department of Biology, Chemistry, and Pharmacy, Freie Universität Berlin, 14195 Berlin, Germany
| | - Andreas Perrot
- Cardiovascular Genetics, Charité - Universitätsmedizin Berlin, 13125 Berlin, Germany
- Experimental and Clinical Research Center, Charité - Universitätsmedizin Berlin, 13125 Berlin, Germany
| | - Cemil Özcelik
- Experimental and Clinical Research Center, Charité - Universitätsmedizin Berlin, 13125 Berlin, Germany
| | - Dennis Harries
- Medical School of Hannover, Institute of Molecular and Cell Physiology, 30625 Hannover, Germany
| | - Faramarz Matinmehr
- Medical School of Hannover, Institute of Molecular and Cell Physiology, 30625 Hannover, Germany
| | - Cristobal Dos Remedios
- Anatomy and Histology, School of Medical Sciences, Bosch Institute, University of Sydney, Camperdown, Sydney, New South Wales 2006, Australia
| | - Christian Mühlfeld
- Institute of Functional and Applied Anatomy, Hannover Medical School, 30625 Hannover, Germany
| | - Theresia Kraft
- Medical School of Hannover, Institute of Molecular and Cell Physiology, 30625 Hannover, Germany
| | - Rolf Bodmer
- Development, Aging and Regeneration Program, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA 92037, USA
| | - Georg Vogler
- Cardiovascular Genetics, Charité - Universitätsmedizin Berlin, 13125 Berlin, Germany
- Development, Aging and Regeneration Program, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA 92037, USA
| | - Silke R Sperling
- Cardiovascular Genetics, Charité - Universitätsmedizin Berlin, 13125 Berlin, Germany
- Berlin Institute of Health (BIH), Berlin, Germany
- DZHK (German Centre for Cardiovascular Research), partner site Berlin, Berlin, Germany
- Department of Biology, Chemistry, and Pharmacy, Freie Universität Berlin, 14195 Berlin, Germany
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12
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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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13
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Radke MH, Polack C, Methawasin M, Fink C, Granzier HL, Gotthardt M. Deleting Full Length Titin Versus the Titin M-Band Region Leads to Differential Mechanosignaling and Cardiac Phenotypes. Circulation 2020; 139:1813-1827. [PMID: 30700140 DOI: 10.1161/circulationaha.118.037588] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
BACKGROUND Titin is a giant elastic protein that spans the half-sarcomere from Z-disk to M-band. It acts as a molecular spring and mechanosensor and has been linked to striated muscle disease. The pathways that govern titin-dependent cardiac growth and contribute to disease are diverse and difficult to dissect. METHODS To study titin deficiency versus dysfunction, the authors generated and compared striated muscle specific knockouts (KOs) with progressive postnatal loss of the complete titin protein by removing exon 2 (E2-KO) or an M-band truncation that eliminates proper sarcomeric integration, but retains all other functional domains (M-band exon 1/2 [M1/2]-KO). The authors evaluated cardiac function, cardiomyocyte mechanics, and the molecular basis of the phenotype. RESULTS Skeletal muscle atrophy with reduced strength, severe sarcomere disassembly, and lethality from 2 weeks of age were shared between the models. Cardiac phenotypes differed considerably: loss of titin leads to dilated cardiomyopathy with combined systolic and diastolic dysfunction-the absence of M-band titin to cardiac atrophy and preserved function. The elastic properties of M1/2-KO cardiomyocytes are maintained, while passive stiffness is reduced in the E2-KO. In both KOs, we find an increased stress response and increased expression of proteins linked to titin-based mechanotransduction (CryAB, ANKRD1, muscle LIM protein, FHLs, p42, Camk2d, p62, and Nbr1). Among them, FHL2 and the M-band signaling proteins p62 and Nbr1 are exclusively upregulated in the E2-KO, suggesting a role in the differential pathology of titin truncation versus deficiency of the full-length protein. The differential stress response is consistent with truncated titin contributing to the mechanical properties in M1/2-KOs, while low titin levels in E2-KOs lead to reduced titin-based stiffness and increased strain on the remaining titin molecules. CONCLUSIONS Progressive depletion of titin leads to sarcomere disassembly and atrophy in striated muscle. In the complete knockout, remaining titin molecules experience increased strain, resulting in mechanically induced trophic signaling and eventually dilated cardiomyopathy. The truncated titin in M1/2-KO helps maintain the passive properties and thus reduces mechanically induced signaling. Together, these findings contribute to the molecular understanding of why titin mutations differentially affect cardiac growth and have implications for genotype-phenotype relations that support a personalized medicine approach to the diverse titinopathies.
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Affiliation(s)
- Michael H Radke
- Neuromuscular and Cardiovascular Cell Biology, Max Delbrück Center for Molecular Medicine, Berlin, Germany (M.H.R., C.P., C.F., M.G.).,DZHK: German Centre for Cardiovascular Research, Partner Site, Berlin, Germany (M.H.R., M.G.)
| | - Christopher Polack
- Neuromuscular and Cardiovascular Cell Biology, Max Delbrück Center for Molecular Medicine, Berlin, Germany (M.H.R., C.P., C.F., M.G.)
| | - Mei Methawasin
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson (M.M., H.G.). The current affiliation for P.S. and T.S. is Department of Medical Microbiology and Hygiene, University Medical Center of the Johannes Gutenberg University Mainz, Germany
| | - Claudia Fink
- Neuromuscular and Cardiovascular Cell Biology, Max Delbrück Center for Molecular Medicine, Berlin, Germany (M.H.R., C.P., C.F., M.G.)
| | - Henk L Granzier
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson (M.M., H.G.). The current affiliation for P.S. and T.S. is Department of Medical Microbiology and Hygiene, University Medical Center of the Johannes Gutenberg University Mainz, Germany
| | - Michael Gotthardt
- Neuromuscular and Cardiovascular Cell Biology, Max Delbrück Center for Molecular Medicine, Berlin, Germany (M.H.R., C.P., C.F., M.G.).,DZHK: German Centre for Cardiovascular Research, Partner Site, Berlin, Germany (M.H.R., M.G.)
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14
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Prill K, Carlisle C, Stannard M, Windsor Reid PJ, Pilgrim DB. Myomesin is part of an integrity pathway that responds to sarcomere damage and disease. PLoS One 2019; 14:e0224206. [PMID: 31644553 PMCID: PMC6808450 DOI: 10.1371/journal.pone.0224206] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Accepted: 10/08/2019] [Indexed: 12/17/2022] Open
Abstract
The structure and function of the sarcomere of striated muscle is well studied but the steps of sarcomere assembly and maintenance remain under-characterized. With the aid of chaperones and factors of the protein quality control system, muscle proteins can be folded and assembled into the contractile apparatus of the sarcomere. When sarcomere assembly is incomplete or the sarcomere becomes damaged, suites of chaperones and maintenance factors respond to repair the sarcomere. Here we show evidence of the importance of the M-line proteins, specifically myomesin, in the monitoring of sarcomere assembly and integrity in previously characterized zebrafish muscle mutants. We show that myomesin is one of the last proteins to be incorporated into the assembling sarcomere, and that in skeletal muscle, its incorporation requires connections with both titin and myosin. In diseased zebrafish sarcomeres, myomesin1a shows an early increase of gene expression, hours before chaperones respond to damaged muscle. We found that myomesin expression is also more specific to sarcomere damage than muscle creatine kinase, and our results and others support the use of myomesin assays as an early, specific, method of detecting muscle damage.
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Affiliation(s)
- Kendal Prill
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - Casey Carlisle
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Megan Stannard
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | | | - David B. Pilgrim
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
- * E-mail:
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15
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Abstract
Alternative splicing is an important mechanism used by the cell to generate greater transcriptomic and proteomic diversity from the genome. In the heart, alternative splicing is increasingly being recognised as an important layer of post-transcriptional gene regulation. Driven by rapidly evolving technologies in next-generation sequencing, alternative splicing has emerged as a crucial process governing complex biological processes during cardiac development and disease. The recent identification of several cardiac splice factors, such as RNA-binding motif protein 20 and 24, not only provided important insight into the mechanisms underlying alternative splicing but also revealed how these splicing factors impact functional properties of the heart. Here, we review our current knowledge of alternative splicing in the heart, with a particular focus on the factors controlling cardiac alternative splicing and their role in cardiomyopathies and subsequent heart failure.
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16
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Zahr HC, Jaalouk DE. Exploring the Crosstalk Between LMNA and Splicing Machinery Gene Mutations in Dilated Cardiomyopathy. Front Genet 2018; 9:231. [PMID: 30050558 PMCID: PMC6052891 DOI: 10.3389/fgene.2018.00231] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2018] [Accepted: 06/11/2018] [Indexed: 12/18/2022] Open
Abstract
Mutations in the LMNA gene, which encodes for the nuclear lamina proteins lamins A and C, are responsible for a diverse group of diseases known as laminopathies. One type of laminopathy is Dilated Cardiomyopathy (DCM), a heart muscle disease characterized by dilation of the left ventricle and impaired systolic function, often leading to heart failure and sudden cardiac death. LMNA is the second most commonly mutated gene in DCM. In addition to LMNA, mutations in more than 60 genes have been associated with DCM. The DCM-associated genes encode a variety of proteins including transcription factors, cytoskeletal, Ca2+-regulating, ion-channel, desmosomal, sarcomeric, and nuclear-membrane proteins. Another important category among DCM-causing genes emerged upon the identification of DCM-causing mutations in RNA binding motif protein 20 (RBM20), an alternative splicing factor that is chiefly expressed in the heart. In addition to RBM20, several essential splicing factors were validated, by employing mouse knock out models, to be embryonically lethal due to aberrant cardiogenesis. Furthermore, heart-specific deletion of some of these splicing factors was found to result in aberrant splicing of their targets and DCM development. In addition to splicing alterations, advances in next generation sequencing highlighted the association between splice-site mutations in several genes and DCM. This review summarizes LMNA mutations and splicing alterations in DCM and discusses how the interaction between LMNA and splicing regulators could possibly explain DCM disease mechanisms.
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Affiliation(s)
| | - Diana E. Jaalouk
- Department of Biology, Faculty of Arts and Sciences, American University of Beirut, Beirut, Lebanon
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17
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18
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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 PMCID: PMC6404781 DOI: 10.1002/cphy.c170023] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [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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19
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Bollen IAE, Ehler E, Fleischanderl K, Bouwman F, Kempers L, Ricke-Hoch M, Hilfiker-Kleiner D, Dos Remedios CG, Krüger M, Vink A, Asselbergs FW, van Spaendonck-Zwarts KY, Pinto YM, Kuster DWD, van der Velden J. Myofilament Remodeling and Function Is More Impaired in Peripartum Cardiomyopathy Compared with Dilated Cardiomyopathy and Ischemic Heart Disease. THE AMERICAN JOURNAL OF PATHOLOGY 2017; 187:2645-2658. [PMID: 28935576 DOI: 10.1016/j.ajpath.2017.08.022] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Revised: 08/21/2017] [Accepted: 08/24/2017] [Indexed: 01/09/2023]
Abstract
Peripartum cardiomyopathy (PPCM) and dilated cardiomyopathy (DCM) show similarities in clinical presentation. However, although DCM patients do not recover and slowly deteriorate further, PPCM patients show either a fast cardiac deterioration or complete recovery. The aim of this study was to assess if underlying cellular changes can explain the clinical similarities and differences in the two diseases. We, therefore, assessed sarcomeric protein expression, modification, titin isoform shift, and contractile behavior of cardiomyocytes in heart tissue of PPCM and DCM patients and compared these with nonfailing controls. Heart samples from ischemic heart disease (ISHD) patients served as heart failure control samples. Passive force was only increased in PPCM samples compared with controls, whereas PPCM, DCM, and ISHD samples all showed increased myofilament Ca2+ sensitivity. Length-dependent activation was significantly impaired in PPCM compared with controls, no impairment was observed in ISHD samples, and DCM samples showed an intermediate response. Contractile impairments were caused by impaired protein kinase A (PKA)-mediated phosphorylation because exogenous PKA restored all parameters to control levels. Although DCM samples showed reexpression of EH-myomesin, an isoform usually only expressed in the heart before birth, PPCM and ISHD did not. The lack of EH-myomesin, combined with low PKA-mediated phosphorylation of myofilament proteins and increased compliant titin isoform, may explain the increase in passive force and blunted length-dependent activation of myofilaments in PPCM samples.
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Affiliation(s)
- Ilse A E Bollen
- Department of Physiology, VU University Medical Center, Amsterdam, the Netherlands; Amsterdam Cardiovascular Sciences, Amsterdam, the Netherlands.
| | - Elisabeth Ehler
- Randall Division of Cell and Molecular Biophysics and Cardiovascular Division, British Heart Foundation Centre of Research Excellence, King's College London, London, United Kingdom
| | - Karin Fleischanderl
- Randall Division of Cell and Molecular Biophysics and Cardiovascular Division, British Heart Foundation Centre of Research Excellence, King's College London, London, United Kingdom
| | - Floor Bouwman
- Department of Physiology, VU University Medical Center, Amsterdam, the Netherlands
| | - Lanette Kempers
- Department of Physiology, VU University Medical Center, Amsterdam, the Netherlands
| | - Melanie Ricke-Hoch
- Department of Cardiology and Angiology, Hannover Medical School, Hannover, Germany
| | | | - Cristobal G Dos Remedios
- Bosch Institute, Discipline of Anatomy and Histology, University of Sydney, Sydney, New South Wales, Australia
| | - Martina Krüger
- Institute of Cardiovascular Physiology, Heinrich-Heine University Düsseldorf, Düsseldorf, Germany
| | - Aryan Vink
- Department of Pathology, University Medical Center Utrecht, Utrecht, the Netherlands
| | - Folkert W Asselbergs
- Division Heart and Lungs, Department of Cardiology, University of Utrecht, University Medical Center Utrecht, Utrecht, the Netherlands; Durrer Center for Cardiogenetic Research, Netherlands Heart Institute, Utrecht, the Netherlands; Institute of Cardiovascular Science, Faculty of Population Health Sciences, University College London, London, United Kingdom
| | - Karin Y van Spaendonck-Zwarts
- Amsterdam Cardiovascular Sciences, Amsterdam, the Netherlands; Department of Clinical Genetics, Academic Medical Center Amsterdam, University of Amsterdam, Amsterdam, the Netherlands
| | - Yigal M Pinto
- Amsterdam Cardiovascular Sciences, Amsterdam, the Netherlands; Amsterdam Medical Center Heart Center, Department of Clinical and Experimental Cardiology, Academic Medical Center Amsterdam, University of Amsterdam, Amsterdam, the Netherlands
| | - Diederik W D Kuster
- Department of Physiology, VU University Medical Center, Amsterdam, the Netherlands; Amsterdam Cardiovascular Sciences, Amsterdam, the Netherlands
| | - Jolanda van der Velden
- Department of Physiology, VU University Medical Center, Amsterdam, the Netherlands; Amsterdam Cardiovascular Sciences, Amsterdam, the Netherlands; Netherlands Heart Institute, Utrecht, the Netherlands
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20
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Kroll K, Chabria M, Wang K, Häusermann F, Schuler F, Polonchuk L. Electro-mechanical conditioning of human iPSC-derived cardiomyocytes for translational research. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2017; 130:212-222. [PMID: 28688751 DOI: 10.1016/j.pbiomolbio.2017.07.003] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Revised: 06/30/2017] [Accepted: 07/03/2017] [Indexed: 11/15/2022]
Abstract
RATIONALE Impaired maturation of human iPSC-derived cardiomyocytes (hiPSC-CMs) currently limits their use in experimental research and further optimization is required to unlock their full potential. OBJECTIVE To push hiPSC-CMs towards maturation, we recapitulated the intrinsic cardiac properties by electro-mechanical stimulation and explored how these mimetic biophysical cues interplay and influence the cell behaviour. METHODS AND RESULTS We introduced a novel device capable of applying synchronized electrical and mechanical stimuli to hiPSC-CM monolayers cultured on a PDMS membrane and evaluated effects of conditioning on cardiomyocyte structure and function. Human iPSC-CMs retained their cardiac phenotype and displayed adaptive structural responses to electrical (E), mechanical (M) and combined electro-mechanical (EM) stimuli, including enhanced membrane N-cadherin signal, stress-fiber formation and sarcomeric length shortening, most prominent under the EM stimulation. On the functional level, EM conditioning significantly reduced the transmembrane calcium current, resulting in a shift towards triangulation of intracellular calcium transients. In contrast, E and M stimulation applied independently increased the proportion of cells with L-Type calcium currents. In addition, calcium transients measured in the M-conditioned samples advanced to a more rectangular shape. CONCLUSION The new methodology is a simple and elegant technique to systematically investigate and manipulate cardiomyocyte remodelling for translational applications. In the present study, we adjusted critical parameters to optimize a regimen for hiPSC-CM transformation. In the future, this technology will open up new avenues for electro-mechanical stimulation by allowing temporal and spatial control of stimuli which can be easily scaled up in complexity for cardiac development and disease modelling.
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Affiliation(s)
- Katharina Kroll
- Roche Pharma Research and Early Development, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd., Grenzacher Str.124, 4070 Basel, Switzerland
| | - Mamta Chabria
- Roche Pharma Research and Early Development, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd., Grenzacher Str.124, 4070 Basel, Switzerland
| | - Ken Wang
- Roche Pharma Research and Early Development, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd., Grenzacher Str.124, 4070 Basel, Switzerland
| | - Fabian Häusermann
- Roche Pharma Research and Early Development, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd., Grenzacher Str.124, 4070 Basel, Switzerland
| | - Franz Schuler
- Roche Pharma Research and Early Development, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd., Grenzacher Str.124, 4070 Basel, Switzerland
| | - Liudmila Polonchuk
- Roche Pharma Research and Early Development, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd., Grenzacher Str.124, 4070 Basel, Switzerland.
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21
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Gautel M, Djinović-Carugo K. The sarcomeric cytoskeleton: from molecules to motion. ACTA ACUST UNITED AC 2016; 219:135-45. [PMID: 26792323 DOI: 10.1242/jeb.124941] [Citation(s) in RCA: 143] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Highly ordered organisation of striated muscle is the prerequisite for the fast and unidirectional development of force and motion during heart and skeletal muscle contraction. A group of proteins, summarised as the sarcomeric cytoskeleton, is essential for the ordered assembly of actin and myosin filaments into sarcomeres, by combining architectural, mechanical and signalling functions. This review discusses recent cell biological, biophysical and structural insight into the regulated assembly of sarcomeric cytoskeleton proteins and their roles in dissipating mechanical forces in order to maintain sarcomere integrity during passive extension and active contraction. α-Actinin crosslinks in the Z-disk show a pivot-and-rod structure that anchors both titin and actin filaments. In contrast, the myosin crosslinks formed by myomesin in the M-band are of a ball-and-spring type and may be crucial in providing stable yet elastic connections during active contractions, especially eccentric exercise.
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Affiliation(s)
- Mathias Gautel
- King's College London BHF Centre of Research Excellence, Randall Division for Cell and Molecular Biophysics, and Cardiovascular Division, New Hunt's House, London SE1 1UL, UK
| | - Kristina Djinović-Carugo
- Department of Structural and Computational Biology, Max F. Perutz Laboratories, University of Vienna, Campus Vienna Biocenter 5, Vienna A-1030, Austria Department of Biochemistry, Faculty of Chemistry and Chemical Technology, University of Ljubljana, Aškerčeva 5, Ljubljana 1000, Slovenia
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22
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Prunotto A, Stevenson BJ, Berthonneche C, Schüpfer F, Beckmann JS, Maurer F, Bergmann S. RNAseq analysis of heart tissue from mice treated with atenolol and isoproterenol reveals a reciprocal transcriptional response. BMC Genomics 2016; 17:717. [PMID: 27604219 PMCID: PMC5015234 DOI: 10.1186/s12864-016-3059-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2016] [Accepted: 09/01/2016] [Indexed: 01/17/2023] Open
Abstract
Background The transcriptional response to many widely used drugs and its modulation by genetic variability is poorly understood. Here we present an analysis of RNAseq profiles from heart tissue of 18 inbred mouse strains treated with the β-blocker atenolol (ATE) and the β-agonist isoproterenol (ISO). Results Differential expression analyses revealed a large set of genes responding to ISO (n = 1770 at FDR = 0.0001) and a comparatively small one responding to ATE (n = 23 at FDR = 0.0001). At a less stringent definition of differential expression, the transcriptional responses to these two antagonistic drugs are reciprocal for many genes, with an overall anti-correlation of r = −0.3. This trend is also observed at the level of most individual strains even though the power to detect differential expression is significantly reduced. The inversely expressed gene sets are enriched with genes annotated for heart-related functions. Modular analysis revealed gene sets that exhibit coherent transcription profiles across some strains and/or treatments. Correlations between these modules and a broad spectrum of cardiovascular traits are stronger than expected by chance. This provides evidence for the overall importance of transcriptional regulation for these organismal responses and explicits links between co-expressed genes and the traits they are associated with. Gene set enrichment analysis of differentially expressed groups of genes pointed to pathways related to heart development and functionality. Conclusions Our study provides new insights into the transcriptional response of the heart to perturbations of the β-adrenergic system, implicating several new genes that had not been associated to this system previously. Electronic supplementary material The online version of this article (doi:10.1186/s12864-016-3059-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Andrea Prunotto
- Department of Medical Genetics, University of Lausanne, Rue du Bugnon 27, 1011, Lausanne, Switzerland.,Swiss Institute of Bioinformatics, Lausanne, Switzerland
| | | | - Corinne Berthonneche
- Service of Medical Genetics, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Rue du Bugnon 27, 1011, Lausanne, Switzerland
| | - Fanny Schüpfer
- Service of Medical Genetics, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Rue du Bugnon 27, 1011, Lausanne, Switzerland
| | - Jacques S Beckmann
- Department of Medical Genetics, University of Lausanne, Rue du Bugnon 27, 1011, Lausanne, Switzerland.,Swiss Institute of Bioinformatics, Lausanne, Switzerland.,Service of Medical Genetics, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Rue du Bugnon 27, 1011, Lausanne, Switzerland
| | - Fabienne Maurer
- Service of Medical Genetics, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Rue du Bugnon 27, 1011, Lausanne, Switzerland.
| | - Sven Bergmann
- Department of Medical Genetics, University of Lausanne, Rue du Bugnon 27, 1011, Lausanne, Switzerland. .,Swiss Institute of Bioinformatics, Lausanne, Switzerland. .,Department of Integrative Biomedical Sciences, University of Cape Town, Cape Town, South Africa.
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23
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Lange S, Gehmlich K, Lun AS, Blondelle J, Hooper C, Dalton ND, Alvarez EA, Zhang X, Bang ML, Abassi YA, Dos Remedios CG, Peterson KL, Chen J, Ehler E. MLP and CARP are linked to chronic PKCα signalling in dilated cardiomyopathy. Nat Commun 2016; 7:12120. [PMID: 27353086 PMCID: PMC4931343 DOI: 10.1038/ncomms12120] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Accepted: 05/31/2016] [Indexed: 11/28/2022] Open
Abstract
MLP (muscle LIM protein)-deficient mice count among the first mouse models for dilated cardiomyopathy (DCM), yet the exact role of MLP in cardiac signalling processes is still enigmatic. Elevated PKCα signalling activity is known to be an important contributor to heart failure. Here we show that MLP directly inhibits the activity of PKCα. In end-stage DCM, PKCα is concentrated at the intercalated disc of cardiomyocytes, where it is sequestered by the adaptor protein CARP in a multiprotein complex together with PLCβ1. In mice deficient for both MLP and CARP the chronic PKCα signalling chain at the intercalated disc is broken and they remain healthy. Our results suggest that the main role of MLP in heart lies in the direct inhibition of PKCα and that chronic uninhibited PKCα activity at the intercalated disc in the absence of functional MLP leads to heart failure. Altered function of the muscle LIM protein (MLP) causes dilated cardiomyopathy in mice and humans. Lange et al. explain the molecular role of MLP in the heart by showing that it affects the signalling complex at the intercalated discs of failing hearts that consists of PKCα, PLCβ1 and CARP by inhibiting PKCα auto-phosphorylation and function.
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Affiliation(s)
- Stephan Lange
- School of Medicine, University of California, San Diego, La Jolla CA-92093, USA
| | - Katja Gehmlich
- BHF Centre of Research Excellence Oxford, Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford OX3 9DU, UK
| | - Alexander S Lun
- School of Medicine, University of California, San Diego, La Jolla CA-92093, USA
| | - Jordan Blondelle
- School of Medicine, University of California, San Diego, La Jolla CA-92093, USA
| | - Charlotte Hooper
- BHF Centre of Research Excellence Oxford, Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford OX3 9DU, UK
| | - Nancy D Dalton
- School of Medicine, University of California, San Diego, La Jolla CA-92093, USA
| | - Erika A Alvarez
- School of Medicine, University of California, San Diego, La Jolla CA-92093, USA
| | - Xiaoyu Zhang
- ACEA Biosciences, 6779 Mesa Ridge Rd #100, San Diego, CA-92121, USA
| | - Marie-Louise Bang
- Institute of Genetic and Biomedical Research, UOS Milan, National Research Council, Rozzano (Milan) 20089, Italy.,Humanitas Clinical and Research Center, Rozzano (Milan) 20089, Italy
| | - Yama A Abassi
- ACEA Biosciences, 6779 Mesa Ridge Rd #100, San Diego, CA-92121, USA
| | | | - Kirk L Peterson
- School of Medicine, University of California, San Diego, La Jolla CA-92093, USA
| | - Ju Chen
- School of Medicine, University of California, San Diego, La Jolla CA-92093, USA
| | - Elisabeth Ehler
- BHF Centre of Research Excellence at King's College London, Cardiovascular Division and Randall Division of Cell and Molecular Biophysics, London SE1 1UL, UK
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24
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Abstract
RNA splicing represents a post-transcriptional mechanism to generate multiple functional RNAs or proteins from a single transcript. The evolution of RNA splicing is a prime example of the Darwinian function follows form concept. A mutation that leads to a new mRNA (form) that encodes for a new functional protein (function) is likely to be retained, and this way, the genome has gradually evolved to encode for genes with multiple isoforms, thereby creating an enormously diverse transcriptome. Advances in technologies to characterize RNA populations have led to a better understanding of RNA processing in health and disease. In the heart, alternative splicing is increasingly being recognized as an important layer of post-transcriptional gene regulation. Moreover, the recent identification of several cardiac splice factors, such as RNA-binding motif protein 20 and SF3B1, not only provided important insight into the mechanisms underlying alternative splicing but also revealed how these splicing factors impact functional properties of the heart. Here, we review our current knowledge of alternative splicing in the heart, with a particular focus on the major and minor spliceosome, the factors controlling RNA splicing, and the role of alternative splicing in cardiac development and disease.
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Affiliation(s)
- Maarten M.G. van den Hoogenhof
- From the Department of Experimental Cardiology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Yigal M. Pinto
- From the Department of Experimental Cardiology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Esther E. Creemers
- From the Department of Experimental Cardiology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
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25
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Dlamini Z, Tshidino SC, Hull R. Abnormalities in Alternative Splicing of Apoptotic Genes and Cardiovascular Diseases. Int J Mol Sci 2015; 16:27171-90. [PMID: 26580598 PMCID: PMC4661875 DOI: 10.3390/ijms161126017] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Revised: 08/06/2015] [Accepted: 08/17/2015] [Indexed: 01/23/2023] Open
Abstract
Apoptosis is required for normal heart development in the embryo, but has also been shown to be an important factor in the occurrence of heart disease. Alternative splicing of apoptotic genes is currently emerging as a diagnostic and therapeutic target for heart disease. This review addresses the involvement of abnormalities in alternative splicing of apoptotic genes in cardiac disorders including cardiomyopathy, myocardial ischemia and heart failure. Many pro-apoptotic members of the Bcl-2 family have alternatively spliced isoforms that lack important active domains. These isoforms can play a negative regulatory role by binding to and inhibiting the pro-apoptotic forms. Alternative splicing is observed to be increased in various cardiovascular diseases with the level of alternate transcripts increasing elevated in diseased hearts compared to healthy subjects. In many cases these isoforms appear to be the underlying cause of the disease, while in others they may be induced in response to cardiovascular pathologies. Regardless of this, the detection of alternate splicing events in the heart can serve as useful diagnostic or prognostic tools, while those splicing events that seem to play a causative role in cardiovascular disease make attractive future drug targets.
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Affiliation(s)
- Zodwa Dlamini
- Research, Innovation and Engagements, Mangosuthu University of Technology, Durban 4026, South Africa.
| | - Shonisani C Tshidino
- Department of Biochemistry, Microbiology and Biotechnology, University of Limpopo, Polokwane 0727, South Africa.
| | - Rodney Hull
- College of Agriculture and Environmental Sciences, Department of Life and Consumer Sciences, Florida Science Campus, University of South Africa, Johannesburg 1709, South Africa.
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26
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Ehler E. Cardiac cytoarchitecture - why the "hardware" is important for heart function! BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2015; 1863:1857-63. [PMID: 26577135 PMCID: PMC5104690 DOI: 10.1016/j.bbamcr.2015.11.006] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Revised: 11/05/2015] [Accepted: 11/09/2015] [Indexed: 01/05/2023]
Abstract
Cells that constitute fully differentiated tissues are characterised by an architecture that makes them perfectly suited for the job they have to do. This is especially obvious for cardiomyocytes, which have an extremely regular shape and display a paracrystalline arrangement of their cytoplasmic components. This article will focus on the two major cytoskeletal multiprotein complexes that are found in cardiomyocytes, the myofibrils, which are responsible for contraction and the intercalated disc, which mediates mechanical and electrochemical contact between individual cardiomyocytes. Recent studies have revealed that these two sites are also crucial in sensing excessive mechanical strain. Signalling processes will be triggered that## lead to changes in gene expression and eventually lead to an altered cardiac cytoarchitecture in the diseased heart, which results in a compromised function. Thus, understanding these changes and the signals that lead to them is crucial to design treatment strategies that can attenuate these processes. This article is part of a Special Issue entitled: Cardiomyocyte Biology: Integration of Developmental and Environmental Cues in the Heart edited by Marcus Schaub and Hughes Abriel.
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Affiliation(s)
- Elisabeth Ehler
- BHF Centre of Research Excellence at King's College London, Cardiovascular Division and Randall Division of Cell and Molecular Biophysics, London, UK.
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27
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The sarcomeric M-region: a molecular command center for diverse cellular processes. BIOMED RESEARCH INTERNATIONAL 2015; 2015:714197. [PMID: 25961035 PMCID: PMC4413555 DOI: 10.1155/2015/714197] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Accepted: 02/08/2015] [Indexed: 02/07/2023]
Abstract
The sarcomeric M-region anchors thick filaments and withstands the mechanical stress of contractions by deformation, thus enabling distribution of physiological forces along the length of thick filaments. While the role of the M-region in supporting myofibrillar structure and contractility is well established, its role in mediating additional cellular processes has only recently started to emerge. As such, M-region is the hub of key protein players contributing to cytoskeletal remodeling, signal transduction, mechanosensing, metabolism, and proteasomal degradation. Mutations in genes encoding M-region related proteins lead to development of severe and lethal cardiac and skeletal myopathies affecting mankind. Herein, we describe the main cellular processes taking place at the M-region, other than thick filament assembly, and discuss human myopathies associated with mutant or truncated M-region proteins.
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28
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Beauchamp P, Moritz W, Kelm JM, Ullrich ND, Agarkova I, Anson BD, Suter TM, Zuppinger C. Development and Characterization of a Scaffold-Free 3D Spheroid Model of Induced Pluripotent Stem Cell-Derived Human Cardiomyocytes. Tissue Eng Part C Methods 2015; 21:852-61. [PMID: 25654582 DOI: 10.1089/ten.tec.2014.0376] [Citation(s) in RCA: 119] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Cardiomyocytes (CMs) are terminally differentiated cells in the adult heart, and ischemia and cardiotoxic compounds can lead to cell death and irreversible decline of cardiac function. As testing platforms, isolated organs and primary cells from rodents have been the standard in research and toxicology, but there is a need for better models that more faithfully recapitulate native human biology. Hence, a new in vitro model comprising the advantages of 3D cell culture and the availability of induced pluripotent stem cells (iPSCs) of human origin was developed and characterized. Human CMs derived from iPSCs were studied in standard 2D culture and as cardiac microtissues (MTs) formed in hanging drops. Two-dimensional cultures were examined using immunofluorescence microscopy and western blotting, while the cardiac MTs were subjected to immunofluorescence, contractility, and pharmacological investigations. iPSC-derived CMs in 2D culture showed well-formed myofibrils, cell-cell contacts positive for connexin-43, and other typical cardiac proteins. The cells reacted to prohypertrophic growth factors with a substantial increase in myofibrils and sarcomeric proteins. In hanging drop cultures, iPSC-derived CMs formed spheroidal MTs within 4 days, showing a homogeneous tissue structure with well-developed myofibrils extending throughout the whole spheroid without a necrotic core. MTs showed spontaneous contractions for more than 4 weeks that were recorded by optical motion tracking, sensitive to temperature and responsive to electrical pacing. Contractile pharmacology was tested with several agents known to modulate cardiac rate and viability. Calcium transients underlay the contractile activity and were also responsive to electrical stimulation, caffeine-induced Ca(2+) release, and extracellular calcium levels. A three-dimensional culture using iPSC-derived human CMs provides an organoid human-based cellular platform that is free of necrosis and recapitulates vital cardiac functionality, thereby providing a new and promising relevant model for the evaluation and development of new therapies and detection of cardiotoxicity.
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Affiliation(s)
- Philippe Beauchamp
- 1 Department of Clinical Research, Cardiology, Bern University Hospital , Bern, Switzerland
| | | | | | - Nina D Ullrich
- 3 Department of Physiology, Bern University , Bühlplatz, Bern, Switzerland .,4 Department of Physiology and Pathophysiology, Heidelberg University , Heidelberg, Germany
| | | | - Blake D Anson
- 5 Cellular Dynamics International , Madison, Wisconsin
| | - Thomas M Suter
- 1 Department of Clinical Research, Cardiology, Bern University Hospital , Bern, Switzerland
| | - Christian Zuppinger
- 1 Department of Clinical Research, Cardiology, Bern University Hospital , Bern, Switzerland
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29
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Pluess M, Daeubler G, Dos Remedios CG, Ehler E. Adaptations of cytoarchitecture in human dilated cardiomyopathy. Biophys Rev 2015; 7:25-32. [PMID: 28509975 PMCID: PMC4322184 DOI: 10.1007/s12551-014-0146-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2014] [Accepted: 11/10/2014] [Indexed: 12/30/2022] Open
Abstract
Hypertrophic cardiomyopathy is characterised by a histological phenotype of myocyte disarray, but heart tissue samples from patients with dilated cardiomyopathy (DCM) often look comparatively similar to those from healthy individuals apart from conspicuous regions of fibrosis and necrosis. We have previously investigated subcellular alterations in the cytoarchitecture of mouse models of dilated cardiomyopathy and found that both the organisation and composition of the intercalated disc, i.e. the specialised type of cell-cell contact in the heart, is altered. There is also is a change in the composition of the M-band of the sarcomere due to an expression shift towards the more extensible embryonic heart (EH)-myomesin isoform. Analysis of human samples from the Sydney Human Heart Tissue Bank have revealed similar structural findings and also provided evidence for a dramatic change in overall cardiomyocyte size control, which has also been seen in the mouse. Together these changes in cytoarchitecture probably contribute to the decreased functional output that is seen in DCM.
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Affiliation(s)
- Marlene Pluess
- Randall Division of Cell and Molecular Biophysics and Cardiovascular Division, British Heart Foundation Centre of Research Excellence, King's College London, New Hunt's House, Guy's Campus, London, SE1 1UL, UK
| | - Gregor Daeubler
- Randall Division of Cell and Molecular Biophysics and Cardiovascular Division, British Heart Foundation Centre of Research Excellence, King's College London, New Hunt's House, Guy's Campus, London, SE1 1UL, UK
| | | | - Elisabeth Ehler
- Randall Division of Cell and Molecular Biophysics and Cardiovascular Division, British Heart Foundation Centre of Research Excellence, King's College London, New Hunt's House, Guy's Campus, London, SE1 1UL, UK.
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30
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Weeland CJ, van den Hoogenhof MM, Beqqali A, Creemers EE. Insights into alternative splicing of sarcomeric genes in the heart. J Mol Cell Cardiol 2015; 81:107-13. [PMID: 25683494 DOI: 10.1016/j.yjmcc.2015.02.008] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/04/2014] [Revised: 01/15/2015] [Accepted: 02/05/2015] [Indexed: 12/14/2022]
Abstract
Driven by rapidly evolving technologies in next-generation sequencing, alternative splicing has emerged as a crucial layer in gene expression, greatly expanding protein diversity and governing complex biological processes in the cardiomyocyte. At the core of cardiac contraction, the physical properties of the sarcomere are carefully orchestrated through alternative splicing to fit the varying demands on the heart. By the recent discovery of RBM20 and RBM24, two major heart and skeletal muscle-restricted splicing factors, it became evident that alternative splicing events in the heart occur in regulated networks rather than in isolated events. Analysis of knockout mice of these splice factors has shed light on the importance of these fundamental processes in the heart. In this review, we discuss recent advances in our understanding of the role and regulation of alternative splicing in the developing and diseased heart, specifically within the sarcomere. Through various examples (titin, myomesin, troponin T, tropomyosin and LDB3) we illustrate how alternative splicing regulates the functional properties of the sarcomere. Finally, we evaluate opportunities and obstacles to modulate alternative splicing in therapeutic approaches for cardiac disease.
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Affiliation(s)
- Cornelis J Weeland
- Experimental Cardiology, Academic Medical Center, Meibergdreef 15, 1105AZ Amsterdam, The Netherlands
| | | | - Abdelaziz Beqqali
- Experimental Cardiology, Academic Medical Center, Meibergdreef 15, 1105AZ Amsterdam, The Netherlands
| | - Esther E Creemers
- Experimental Cardiology, Academic Medical Center, Meibergdreef 15, 1105AZ Amsterdam, The Netherlands.
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31
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Torre I, González-Tendero A, García-Cañadilla P, Crispi F, García-García F, Bijnens B, Iruretagoyena I, Dopazo J, Amat-Roldán I, Gratacós E. Permanent cardiac sarcomere changes in a rabbit model of intrauterine growth restriction. PLoS One 2014; 9:e113067. [PMID: 25402351 PMCID: PMC4234642 DOI: 10.1371/journal.pone.0113067] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2014] [Accepted: 10/19/2014] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND Intrauterine growth restriction (IUGR) induces fetal cardiac remodelling and dysfunction, which persists postnatally and may explain the link between low birth weight and increased cardiovascular mortality in adulthood. However, the cellular and molecular bases for these changes are still not well understood. We tested the hypothesis that IUGR is associated with structural and functional gene expression changes in the fetal sarcomere cytoarchitecture, which remain present in adulthood. METHODS AND RESULTS IUGR was induced in New Zealand pregnant rabbits by selective ligation of the utero-placental vessels. Fetal echocardiography demonstrated more globular hearts and signs of cardiac dysfunction in IUGR. Second harmonic generation microscopy (SHGM) showed shorter sarcomere length and shorter A-band and thick-thin filament interaction lengths, that were already present in utero and persisted at 70 postnatal days (adulthood). Sarcomeric M-band (GO: 0031430) functional term was over-represented in IUGR fetal hearts. CONCLUSION The results suggest that IUGR induces cardiac dysfunction and permanent changes on the sarcomere.
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Affiliation(s)
- Iratxe Torre
- BCNatal – Barcelona Center for Maternal-Fetal and Neonatal Medicine (Hospital Clínic and Hospital Sant Joan de Deu), IDIBAPS, University of Barcelona, and Centre for Biomedical Research on Rare Diseases (CIBER-ER), Barcelona, Spain
| | - Anna González-Tendero
- BCNatal – Barcelona Center for Maternal-Fetal and Neonatal Medicine (Hospital Clínic and Hospital Sant Joan de Deu), IDIBAPS, University of Barcelona, and Centre for Biomedical Research on Rare Diseases (CIBER-ER), Barcelona, Spain
| | - Patricia García-Cañadilla
- BCNatal – Barcelona Center for Maternal-Fetal and Neonatal Medicine (Hospital Clínic and Hospital Sant Joan de Deu), IDIBAPS, University of Barcelona, and Centre for Biomedical Research on Rare Diseases (CIBER-ER), Barcelona, Spain
- Physense, Departament de Tecnologies de la Informació i les Comunicacions (DTIC), Universitat Pompeu Fabra, Barcelona, Spain
| | - Fátima Crispi
- BCNatal – Barcelona Center for Maternal-Fetal and Neonatal Medicine (Hospital Clínic and Hospital Sant Joan de Deu), IDIBAPS, University of Barcelona, and Centre for Biomedical Research on Rare Diseases (CIBER-ER), Barcelona, Spain
| | - Francisco García-García
- Bioinformatics Department, Centro de Investigación Principe Felipe (CIPF), Valencia, Spain
- Functional Genomics Node, INB, CIPF, Valencia, Spain
| | - Bart Bijnens
- ICREA, Universitat Pompeu Fabra, Barcelona, Spain
| | - Igor Iruretagoyena
- BCNatal – Barcelona Center for Maternal-Fetal and Neonatal Medicine (Hospital Clínic and Hospital Sant Joan de Deu), IDIBAPS, University of Barcelona, and Centre for Biomedical Research on Rare Diseases (CIBER-ER), Barcelona, Spain
| | - Joaquin Dopazo
- Bioinformatics Department, Centro de Investigación Principe Felipe (CIPF), Valencia, Spain
- Functional Genomics Node, INB, CIPF, Valencia, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), CIPF, Valencia, Spain
| | - Ivan Amat-Roldán
- BCNatal – Barcelona Center for Maternal-Fetal and Neonatal Medicine (Hospital Clínic and Hospital Sant Joan de Deu), IDIBAPS, University of Barcelona, and Centre for Biomedical Research on Rare Diseases (CIBER-ER), Barcelona, Spain
| | - Eduard Gratacós
- BCNatal – Barcelona Center for Maternal-Fetal and Neonatal Medicine (Hospital Clínic and Hospital Sant Joan de Deu), IDIBAPS, University of Barcelona, and Centre for Biomedical Research on Rare Diseases (CIBER-ER), Barcelona, Spain
- * E-mail:
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32
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Sequeira V, Nijenkamp LLAM, Regan JA, van der Velden J. The physiological role of cardiac cytoskeleton and its alterations in heart failure. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1838:700-22. [PMID: 23860255 DOI: 10.1016/j.bbamem.2013.07.011] [Citation(s) in RCA: 120] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2013] [Revised: 07/01/2013] [Accepted: 07/08/2013] [Indexed: 12/11/2022]
Abstract
Cardiac muscle cells are equipped with specialized biochemical machineries for the rapid generation of force and movement central to the work generated by the heart. During each heart beat cardiac muscle cells perceive and experience changes in length and load, which reflect one of the fundamental principles of physiology known as the Frank-Starling law of the heart. Cardiac muscle cells are unique mechanical stretch sensors that allow the heart to increase cardiac output, and adjust it to new physiological and pathological situations. In the present review we discuss the mechano-sensory role of the cytoskeletal proteins with respect to their tight interaction with the sarcolemma and extracellular matrix. The role of contractile thick and thin filament proteins, the elastic protein titin, and their anchorage at the Z-disc and M-band, with associated proteins are reviewed in physiologic and pathologic conditions leading to heart failure. This article is part of a Special Issue entitled: Reciprocal influences between cell cytoskeleton and membrane channels, receptors and transporters. Guest Editor: Jean Claude Hervé
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Affiliation(s)
- Vasco Sequeira
- Laboratory for Physiology, Institute for Cardiovascular Research, VU University Medical Center, van der Boechorststraat 7, 1081 BT Amsterdam, The Netherlands
| | - Louise L A M Nijenkamp
- Laboratory for Physiology, Institute for Cardiovascular Research, VU University Medical Center, van der Boechorststraat 7, 1081 BT Amsterdam, The Netherlands
| | - Jessica A Regan
- Laboratory for Physiology, Institute for Cardiovascular Research, VU University Medical Center, van der Boechorststraat 7, 1081 BT Amsterdam, The Netherlands; Department of Physiology, Molecular Cardiovascular Research Program, Sarver Heart Center, University of Arizona, Tucson, AZ 85724, USA
| | - Jolanda van der Velden
- Laboratory for Physiology, Institute for Cardiovascular Research, VU University Medical Center, van der Boechorststraat 7, 1081 BT Amsterdam, The Netherlands; ICIN-Netherlands Heart Institute, The Netherlands.
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33
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The alternative heart: impact of alternative splicing in heart disease. J Cardiovasc Transl Res 2013; 6:945-55. [PMID: 23775418 DOI: 10.1007/s12265-013-9482-z] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/07/2013] [Accepted: 06/04/2013] [Indexed: 01/16/2023]
Abstract
Alternative splicing is the main driver of protein diversity and allows the production of different proteins from each gene in the genome. Changes in exon exclusion, intron retention or the use of alternative splice sites can alter protein structure, localisation, regulation and function. In the heart, alternative splicing of sarcomeric genes, ion channels and cell signalling proteins can lead to cardiomyopathies, arrhythmias and other pathologies. Also, a number of inherited conditions and heart-related diseases develop as a result of mutations affecting splicing. Here, we review the impact that changes in alternative splicing have on individual genes and on whole biological processes associated with heart disease. We also discuss promising therapeutic tools based on the manipulation of alternative splicing.
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34
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Wilson AJ, Schoenauer R, Ehler E, Agarkova I, Bennett PM. Cardiomyocyte growth and sarcomerogenesis at the intercalated disc. Cell Mol Life Sci 2013; 71:165-81. [PMID: 23708682 PMCID: PMC3889684 DOI: 10.1007/s00018-013-1374-5] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2013] [Revised: 04/27/2013] [Accepted: 05/13/2013] [Indexed: 12/02/2022]
Abstract
Cardiomyocytes grow during heart maturation or disease-related cardiac remodeling. We present evidence that the intercalated disc (ID) is integral to both longitudinal and lateral growth: increases in width are accommodated by lateral extension of the plicate tread regions and increases in length by sarcomere insertion within the ID. At the margin between myofibril and the folded membrane of the ID lies a transitional junction through which the thin filaments from the last sarcomere run to the ID membrane and it has been suggested that this junction acts as a proto Z-disc for sarcomere addition. In support of this hypothesis, we have investigated the ultrastructure of the ID in mouse hearts from control and dilated cardiomyopathy (DCM) models, the MLP-null and a cardiac-specific β-catenin mutant, cΔex3, as well as in human left ventricle from normal and DCM samples. We find that the ID amplitude can vary tenfold from 0.2 μm up to a maximum of ~2 μm allowing gradual expansion during heart growth. At the greatest amplitude, equivalent to a sarcomere length, A-bands and thick filaments are found within the ID membrane loops together with a Z-disc, which develops at the transitional junction position. Here, also, the tops of the membrane folds, which are rich in αII spectrin, become enlarged and associated with junctional sarcoplasmic reticulum. Systematically larger ID amplitudes are found in DCM samples. Other morphological differences between mouse DCM and normal hearts suggest that sarcomere inclusion is compromised in the diseased hearts.
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Affiliation(s)
- Amanda J Wilson
- Randall Division of Cell and Molecular Biophysics, King's College London, New Hunt's House, Guy's Campus, London, SE1 1UL, UK,
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35
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Peche VS, Holak TA, Burgute BD, Kosmas K, Kale SP, Wunderlich FT, Elhamine F, Stehle R, Pfitzer G, Nohroudi K, Addicks K, Stöckigt F, Schrickel JW, Gallinger J, Schleicher M, Noegel AA. Ablation of cyclase-associated protein 2 (CAP2) leads to cardiomyopathy. Cell Mol Life Sci 2013; 70:527-43. [PMID: 22945801 PMCID: PMC11113306 DOI: 10.1007/s00018-012-1142-y] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2012] [Revised: 08/01/2012] [Accepted: 08/14/2012] [Indexed: 12/24/2022]
Abstract
Cyclase-associated proteins are highly conserved proteins that have a role in the regulation of actin dynamics. Higher eukaryotes have two isoforms, CAP1 and CAP2. To study the in vivo function of CAP2, we generated mice in which the CAP2 gene was inactivated by a gene-trap approach. Mutant mice showed a decrease in body weight and had a decreased survival rate. Further, they developed a severe cardiac defect marked by dilated cardiomyopathy (DCM) associated with drastic reduction in basal heart rate and prolongations in atrial and ventricular conduction times. Moreover, CAP2-deficient myofibrils exhibited reduced cooperativity of calcium-regulated force development. At the microscopic level, we observed disarrayed sarcomeres with development of fibrosis. We analyzed CAP2's role in actin assembly and found that it sequesters G-actin and efficiently fragments filaments. This activity resides completely in its WASP homology domain. Thus CAP2 is an essential component of the myocardial sarcomere and is essential for physiological functioning of the cardiac system, and a deficiency leads to DCM and various cardiac defects.
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Affiliation(s)
- Vivek S. Peche
- Institute of Biochemistry I, Medical Faculty, University of Cologne, Joseph-Stelzmann-Str. 52, 50931 Cologne, Germany
- Center for Molecular Medicine Cologne (CMMC), Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
| | - Tad A. Holak
- Max-Planck-Institute of Biochemistry, 82152 Martinsried, Germany
- Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Krakow, Poland
| | - Bhagyashri D. Burgute
- Institute of Biochemistry I, Medical Faculty, University of Cologne, Joseph-Stelzmann-Str. 52, 50931 Cologne, Germany
- Center for Molecular Medicine Cologne (CMMC), Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
| | - Kosmas Kosmas
- Institute of Biochemistry I, Medical Faculty, University of Cologne, Joseph-Stelzmann-Str. 52, 50931 Cologne, Germany
| | - Sushant P. Kale
- Department of Neurology, Southern Illinois University School of Medicine, Springfield, IL USA
| | - F. Thomas Wunderlich
- Center for Molecular Medicine Cologne (CMMC), Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
- Max-Planck-Institute of Neurological Research, Cologne, Germany
| | - Fatiha Elhamine
- Institute of Vegetative Physiology, University of Cologne, Cologne, Germany
| | - Robert Stehle
- Institute of Vegetative Physiology, University of Cologne, Cologne, Germany
| | - Gabriele Pfitzer
- Institute of Vegetative Physiology, University of Cologne, Cologne, Germany
| | - Klaus Nohroudi
- Institute of Anatomy I, University of Cologne, Cologne, Germany
| | - Klaus Addicks
- Institute of Anatomy I, University of Cologne, Cologne, Germany
| | - Florian Stöckigt
- Department of Medicine-Cardiology, University of Bonn, Bonn, Germany
| | - Jan W. Schrickel
- Department of Medicine-Cardiology, University of Bonn, Bonn, Germany
| | - Julia Gallinger
- Institute for Anatomy and Cell Biology, Ludwig-Maximilians University, 80336 Munich, Germany
| | - Michael Schleicher
- Institute for Anatomy and Cell Biology, Ludwig-Maximilians University, 80336 Munich, Germany
| | - Angelika A. Noegel
- Institute of Biochemistry I, Medical Faculty, University of Cologne, Joseph-Stelzmann-Str. 52, 50931 Cologne, Germany
- Center for Molecular Medicine Cologne (CMMC), Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
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Left ventricular remodeling in swine after myocardial infarction: a transcriptional genomics approach. Basic Res Cardiol 2011; 106:1269-81. [PMID: 22057716 PMCID: PMC3228945 DOI: 10.1007/s00395-011-0229-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2011] [Revised: 10/04/2011] [Accepted: 10/20/2011] [Indexed: 01/06/2023]
Abstract
Despite the apparent appropriateness of left ventricular (LV) remodeling following myocardial infarction (MI), it poses an independent risk factor for development of heart failure. There is a paucity of studies into the molecular mechanisms of LV remodeling in large animal species. We took an unbiased molecular approach to identify candidate transcription factors (TFs) mediating the genetic reprogramming involved in post-MI LV remodeling in swine. Left ventricular tissue was collected from remote, non-infarcted myocardium, 3 weeks after MI-induction or sham-surgery. Microarray analysis identified 285 upregulated and 278 downregulated genes (FDR < 0.05). Of these differentially expressed genes, the promoter regions of the human homologs were searched for common TF binding sites (TFBS). Eighteen TFBS were overrepresented >two-fold (p < 0.01) in upregulated and 13 in downregulated genes. Left ventricular nuclear protein extracts were assayed for DNA-binding activity by protein/DNA array. Out of 345 DNA probes, 30 showed signal intensity changes >two-fold. Five TFs were identified in both TFBS and protein/DNA array analyses, which showed matching changes for COUP-TFII and glucocorticoid receptor (GR) only. Treatment of swine with the GR antagonist mifepristone after MI reduced the post-MI increase in LV mass, but LV dilation remained unaffected. Thus, using an unbiased approach to study post-MI LV remodeling in a physiologically relevant large animal model, we identified COUP-TFII and GR as potential key mediators of post-MI remodeling.
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Gehmlich K, Syrris P, Reimann M, Asimaki A, Ehler E, Evans A, Quarta G, Pantazis A, Saffitz JE, McKenna WJ. Molecular changes in the heart of a severe case of arrhythmogenic right ventricular cardiomyopathy caused by a desmoglein-2 null allele. Cardiovasc Pathol 2011; 21:275-82. [PMID: 22036071 DOI: 10.1016/j.carpath.2011.09.005] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/31/2011] [Revised: 07/29/2011] [Accepted: 09/16/2011] [Indexed: 11/25/2022] Open
Abstract
INTRODUCTION Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a genetic disorder caused by mutations in desmosomal genes. It is often associated with life-threatening arrhythmias. Some affected individuals develop progressive heart failure and may require cardiac transplantation. METHODS The explanted heart of a young adult with end-stage heart failure due to a null allele in desmoglein-2 was studied at macroscopic, microscopic, and molecular level. Myocardial samples were probed for junctional localization of desmosomal components and the gap junction protein connexin43 by immunohistochemical staining. In addition, the protein content of desmosomal and adherens junction markers as well as connexin43 was assessed by Western blotting. RESULTS Histological analysis confirmed ARVC. Despite the loss of specific immunoreactive signal for desmosomal components at the cardiac intercalated disks (shown for plakoglobin, desmoplakin, and plakophilin-2), these proteins could be detected by Western blotting. Only for desmoglein-2, desmocollin-2, and plakoglobin were reduced protein levels observed. Adherens junction proteins were not affected. Lower phosphorylation levels were observed for connexin43; however, localization of the gap junction protein displayed regional differences. At the molecular level, disease progression was more severe in the right ventricle compared to the left ventricle. CONCLUSION Our data suggest that, in the ARVC heart, plakoglobin is mainly redistributed from the junctions to other cellular pools and that protein degradation only plays a secondary role. Homogenous changes in the phosphorylation status of connexin43 were observed in multiple ARVC samples, suggesting that this might be a general feature of the disease.
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Affiliation(s)
- Katja Gehmlich
- Institute of Cardiovascular Science and The Heart Hospital, University College London, United Kingdom.
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