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Dhawale N, Labonte D, Holt NC. The effect of muscle ultrastructure on the force, displacement and work capacity of skeletal muscle. J R Soc Interface 2024; 21:20230658. [PMID: 38774960 DOI: 10.1098/rsif.2023.0658] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Accepted: 03/28/2024] [Indexed: 07/31/2024] Open
Abstract
Skeletal muscle powers animal movement through interactions between the contractile proteins, actin and myosin. Structural variation contributes greatly to the variation in mechanical performance observed across muscles. In vertebrates, gross structural variation occurs in the form of changes in the muscle cross-sectional area : fibre length ratio. This results in a trade-off between force and displacement capacity, leaving work capacity unaltered. Consequently, the maximum work per unit volume-the work density-is considered constant. Invertebrate muscle also varies in muscle ultrastructure, i.e. actin and myosin filament lengths. Increasing actin and myosin filament lengths increases force capacity, but the effect on muscle fibre displacement, and thus work, capacity is unclear. We use a sliding-filament muscle model to predict the effect of actin and myosin filament lengths on these mechanical parameters for both idealized sarcomeres with fixed actin : myosin length ratios, and for real sarcomeres with known filament lengths. Increasing actin and myosin filament lengths increases stress without reducing strain capacity. A muscle with longer actin and myosin filaments can generate larger force over the same displacement and has a higher work density, so seemingly bypassing an established trade-off. However, real sarcomeres deviate from the idealized length ratio suggesting unidentified constraints or selective pressures.
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Affiliation(s)
- Nihav Dhawale
- Department of Evolution, Ecology and Organismal Biology, UC Riverside , Riverside, CA, USA
| | - David Labonte
- Department of Bioengineering, Imperial College London , London, UK
| | - Natalie C Holt
- Department of Evolution, Ecology and Organismal Biology, UC Riverside , Riverside, CA, USA
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2
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Cumberland MJ, Euchner J, Azad AJ, T N Vo N, Kirchhof P, Holmes AP, Denning C, Gehmlich K. Generation of a human iPSC-derived cardiomyocyte/fibroblast engineered heart tissue model. F1000Res 2024; 12:1224. [PMID: 38298530 PMCID: PMC10828555 DOI: 10.12688/f1000research.139482.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 02/09/2024] [Indexed: 02/02/2024] Open
Abstract
Animal models have proven integral to broadening our understanding of complex cardiac diseases but have been hampered by significant species-dependent differences in cellular physiology. Human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) have shown great promise in the modelling of cardiac diseases despite limitations in functional and structural maturity. 3D stem cell-derived cardiac models represent a step towards mimicking the intricate microenvironment present in the heart as an in vitro model. Incorporation of non-myocyte cell types, such as cardiac fibroblasts, into engineered heart tissue models (EHTs) can help better recapitulate the cell-to-cell and cell-to-matrix interactions present in the human myocardium. Integration of human-induced pluripotent stem cell-derived cardiac fibroblasts (hiPSC-CFs) and hiPSC-CM into EHT models enables the generation of a genetically homogeneous modelling system capable of exploring the abstruse structural and electrophysiological interplay present in cardiac pathophysiology. Furthermore, the construction of more physiologically relevant 3D cardiac models offers great potential in the replacement of animals in heart disease research. Here we describe efficient and reproducible protocols for the differentiation of hiPSC-CMs and hiPSC-CFs and their subsequent assimilation into EHTs. The resultant EHT consists of longitudinally arranged iPSC-CMs, incorporated alongside hiPSC-CFs. EHTs with both hiPSC-CMs and hiPSC-CFs exhibit slower beating frequencies and enhanced contractile force compared to those composed of hiPSC-CMs alone. The modified protocol may help better characterise the interplay between different cell types in the myocardium and their contribution to structural remodelling and cardiac fibrosis.
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Affiliation(s)
- Max J Cumberland
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, England, B15 2TT, UK
| | - Jonas Euchner
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, England, B15 2TT, UK
- Centre of Membrane Proteins and Receptors, University of Birmingham, Birmingham, England, B15 2TT, UK
| | - Amar J Azad
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, England, B15 2TT, UK
| | - Nguyen T N Vo
- Biodiscovery Institute, University of Nottingham, Nottingham, England, NG7 2RD, UK
| | - Paulus Kirchhof
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, England, B15 2TT, UK
- Department of Cardiology, University Heart and Vascular Center Hamburg, Universitat Hamburg, Hamburg, Hamburg, 20251, Germany
| | - Andrew P Holmes
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, England, B15 2TT, UK
- Institute of Clinical Sciences, University of Birmingham, Birmingham, England, B15 2TT, UK
| | - Chris Denning
- Biodiscovery Institute, University of Nottingham, Nottingham, England, NG7 2RD, UK
| | - Katja Gehmlich
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, England, B15 2TT, UK
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, England, OX3 9DU, UK
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3
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Kellermayer D, Tordai H, Kiss B, Török G, Péter DM, Sayour AA, Pólos M, Hartyánszky I, Szilveszter B, Labeit S, Gángó A, Bedics G, Bödör C, Radovits T, Merkely B, Kellermayer MS. Truncated titin is structurally integrated into the human dilated cardiomyopathic sarcomere. J Clin Invest 2024; 134:e169753. [PMID: 37962957 PMCID: PMC10763722 DOI: 10.1172/jci169753] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Accepted: 11/08/2023] [Indexed: 11/16/2023] Open
Abstract
Heterozygous (HET) truncating variant mutations in the TTN gene (TTNtvs), encoding the giant titin protein, are the most common genetic cause of dilated cardiomyopathy (DCM). However, the molecular mechanisms by which TTNtv mutations induce DCM are controversial. Here, we studied 127 clinically identified DCM human cardiac samples with next-generation sequencing (NGS), high-resolution gel electrophoresis, Western blot analysis, and super-resolution microscopy in order to dissect the structural and functional consequences of TTNtv mutations. The occurrence of TTNtv was found to be 15% in the DCM cohort. Truncated titin proteins matching, by molecular weight, the gene sequence predictions were detected in the majority of the TTNtv+ samples. Full-length titin was reduced in TTNtv+ compared with TTNtv- samples. Proteomics analysis of washed myofibrils and stimulated emission depletion (STED) super-resolution microscopy of myocardial sarcomeres labeled with sequence-specific anti-titin antibodies revealed that truncated titin was structurally integrated into the sarcomere. Sarcomere length-dependent anti-titin epitope position, shape, and intensity analyses pointed at possible structural defects in the I/A junction and the M-band of TTNtv+ sarcomeres, which probably contribute, possibly via faulty mechanosensor function, to the development of manifest DCM.
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Affiliation(s)
- Dalma Kellermayer
- Heart and Vascular Center
- Department of Biophysics and Radiation Biology, and
- 1st Department of Pathology and Experimental Cancer Research, Semmelweis University, Budapest, Hungary
| | | | - Balázs Kiss
- Department of Biophysics and Radiation Biology, and
| | - György Török
- Department of Biophysics and Radiation Biology, and
| | | | | | | | | | | | - Siegfried Labeit
- DZHK Partnersite Mannheim-Heidelberg, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
| | - Ambrus Gángó
- 1st Department of Pathology and Experimental Cancer Research, Semmelweis University, Budapest, Hungary
| | - Gábor Bedics
- 1st Department of Pathology and Experimental Cancer Research, Semmelweis University, Budapest, Hungary
| | - Csaba Bödör
- 1st Department of Pathology and Experimental Cancer Research, Semmelweis University, Budapest, Hungary
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4
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Qian Z, Ping L, Xuelin Z. Re‑examining the mechanism of eccentric exercise‑induced skeletal muscle damage from the role of the third filament, titin (Review). Biomed Rep 2024; 20:14. [PMID: 38124762 PMCID: PMC10731162 DOI: 10.3892/br.2023.1703] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2023] [Accepted: 10/23/2023] [Indexed: 12/23/2023] Open
Abstract
Intense and unaccustomed eccentric exercise has been extensively studied for its ability to induce muscle damage. However, the underlying mechanism of this phenomenon still requires further clarification. This knowledge gap arises from the need for explanation of the eccentric contraction through the sliding filament theory. The two-filament sarcomere model, which is consisted of thin and thick filaments, forms the basis of the sliding filament theory. The mechanisms of concentric and isometric contractions at the cellular and molecular levels are effectively described by this model. However, when relying solely on the cross-bridge swing, the sliding filament theory fails to account for specific observations, such as the stability of the descending limb of the force-length relationship curve. Recent evidence indicated that titin and the extracellular matrix (ECM) may play a protective role by interacting with the thick and thin filaments. During an eccentric contraction, titin serves as a third filament in the sarcomere, which helps regulate changes in passive force. The two-filament sarcomere model has limitations in explaining eccentric contraction, thus this compensates for those shortcomings. The present review explored the potential of replacing the two-filament sarcomere model with a three-filament sarcomere model, incorporating thin filaments, thick filaments and titin. This revised model offers a more comprehensive explanation of eccentric contraction phenomena. Furthermore, the sliding filament theory was investigated in the context of the three-filament sarcomere model. The double-layer protection mechanism, which involves increased titin stiffness and the ECM during eccentric contraction was explored. This mechanism may enhance lateral force transmission between muscle fibers and the ECM, resulting in sarcolemma and ECM shear deformation. These findings provided insight into the mechanism of eccentric exercise-induced skeletal muscle damage. Considering the three-filament sarcomere model and the double-layer protection mechanism, the present review offered a more logical and comprehensive understanding of the mechanism behind eccentric exercise-induced muscle damage.
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Affiliation(s)
- Zhao Qian
- College of Physical Education, Qufu Normal University, Jining, Shandong 273165, P.R. China
| | - Liu Ping
- College of Physical Education, Qufu Normal University, Jining, Shandong 273165, P.R. China
| | - Zhang Xuelin
- College of Physical Education, Qufu Normal University, Jining, Shandong 273165, P.R. China
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Nalbant P, Wagner J, Dehmelt L. Direct investigation of cell contraction signal networks by light-based perturbation methods. Pflugers Arch 2023; 475:1439-1452. [PMID: 37851146 DOI: 10.1007/s00424-023-02864-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Revised: 08/21/2023] [Accepted: 09/21/2023] [Indexed: 10/19/2023]
Abstract
Cell contraction plays an important role in many physiological and pathophysiological processes. This includes functions in skeletal, heart, and smooth muscle cells, which lead to highly coordinated contractions of multicellular assemblies, and functions in non-muscle cells, which are often highly localized in subcellular regions and transient in time. While the regulatory processes that control cell contraction in muscle cells are well understood, much less is known about cell contraction in non-muscle cells. In this review, we focus on the mechanisms that control cell contraction in space and time in non-muscle cells, and how they can be investigated by light-based methods. The review particularly focusses on signal networks and cytoskeletal components that together control subcellular contraction patterns to perform functions on the level of cells and tissues, such as directional migration and multicellular rearrangements during development. Key features of light-based methods that enable highly local and fast perturbations are highlighted, and how experimental strategies can capitalize on these features to uncover causal relationships in the complex signal networks that control cell contraction.
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Affiliation(s)
- Perihan Nalbant
- Department of Molecular Cell Biology, Center of Medical Biotechnology, University of Duisburg-Essen, Room T03 R01 D33, Universitätsstrasse 2, 45141, Essen, Germany.
| | - Jessica Wagner
- Department of Molecular Cell Biology, Center of Medical Biotechnology, University of Duisburg-Essen, Room T03 R01 D33, Universitätsstrasse 2, 45141, Essen, Germany
| | - Leif Dehmelt
- Department of Systemic Cell Biology, Fakultät für Chemie und Chemische Biologie, Max Planck Institute of Molecular Physiology, and Dortmund University of Technology, Room CP-02-157, Otto-Hahn-Str. 4a, 44227, Dortmund, Germany.
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6
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Wacker J, Di Bernardo S, Lobrinus JA, Jungbluth H, Gautel M, Beghetti M, Fluss J. Successful heart transplant in a child with congenital core myopathy and delayed-onset restrictive cardiomyopathy due to recessive mutations in the titin (TTN) gene. Pediatr Transplant 2023; 27:e14561. [PMID: 37345726 DOI: 10.1111/petr.14561] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/02/2023] [Revised: 05/24/2023] [Accepted: 06/13/2023] [Indexed: 06/23/2023]
Abstract
BACKGROUND Mutations in the TTN gene, encoding the muscle filament titin, are a major cause of inherited dilated cardiomyopathy. Early-onset skeletal muscle disorders due to recessive TTN mutations have recently been described, sometimes associated with cardiomyopathies. CASE DESCRIPTION We report the case of a boy with congenital core myopathy due to compound heterozygosity for TTN variants. He presented in infancy with rapidly evolving restrictive cardiomyopathy, requiring heart transplantation at the age of 5 years with favorable long-term cardiac and neuromuscular outcome. CONCLUSION Heart transplantation may have a role in selected patients with TTN-related congenital myopathy with disproportionally severe cardiac presentation compared to skeletal and respiratory muscle involvement.
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Affiliation(s)
- Julie Wacker
- Pediatric Cardiology Unit, University Hospitals of Geneva, Faculty of Medicine, University of Geneva, Geneva, Switzerland
- Centre Universitaire Romand de Cardiologie et Chirurgie Cardiaque Pédiatrique, University Hospitals of Geneva, Geneva, Switzerland
| | - Stefano Di Bernardo
- Centre Universitaire Romand de Cardiologie et Chirurgie Cardiaque Pédiatrique, University Hospitals of Geneva, Geneva, Switzerland
- Pediatric Cardiology, Department of Pediatrics, Lausanne University Hospital, Lausanne, Switzerland
| | | | - Heinz Jungbluth
- Department of Paediatric Neurology, Neuromuscular Service, Evelina's Children Hospital, Guy's & St. Thomas' Hospital NHS Foundation Trust, London, UK
- Randall Centre for Cell and Molecular Biophysics, King's College London BHF Centre of Research Excellence, London, UK
| | - Mathias Gautel
- Randall Centre for Cell and Molecular Biophysics, King's College London BHF Centre of Research Excellence, London, UK
| | - Maurice Beghetti
- Pediatric Cardiology Unit, University Hospitals of Geneva, Faculty of Medicine, University of Geneva, Geneva, Switzerland
- Centre Universitaire Romand de Cardiologie et Chirurgie Cardiaque Pédiatrique, University Hospitals of Geneva, Geneva, Switzerland
| | - Joel Fluss
- Pediatric Neurology Unit, University Hospitals of Geneva, Faculty of Medicine, University of Geneva, Geneva, Switzerland
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7
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Zhang N, Zhang Y, Xu J, Wang P, Wu B, Lu S, Lu X, You S, Huang X, Li M, Zou Y, Liu M, Zhao Y, Sun G, Wang W, Geng D, Liu J, Cao L, Sun Y. α-myosin heavy chain lactylation maintains sarcomeric structure and function and alleviates the development of heart failure. Cell Res 2023; 33:679-698. [PMID: 37443257 PMCID: PMC10474270 DOI: 10.1038/s41422-023-00844-w] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Accepted: 06/21/2023] [Indexed: 07/15/2023] Open
Abstract
The sarcomeric interaction of α-myosin heavy chain (α-MHC) with Titin is vital for cardiac structure and contraction. However, the mechanism regulating this interaction in normal and failing hearts remains unknown. Lactate is a crucial energy substrate of the heart. Here, we identify that α-MHC undergoes lactylation on lysine 1897 to regulate the interaction of α-MHC with Titin. We observed a reduction of α-MHC K1897 lactylation in mice and patients with heart failure. Loss of K1897 lactylation in α-MHC K1897R knock-in mice reduces α-MHC-Titin interaction and leads to impaired cardiac structure and function. Furthermore, we identified that p300 and Sirtuin 1 act as the acyltransferase and delactylase of α-MHC, respectively. Decreasing lactate production by chemical or genetic manipulation reduces α-MHC lactylation, impairs α-MHC-Titin interaction and worsens heart failure. By contrast, upregulation of the lactate concentration by administering sodium lactate or inhibiting the pivotal lactate transporter in cardiomyocytes can promote α-MHC K1897 lactylation and α-MHC-Titin interaction, thereby alleviating heart failure. In conclusion, α-MHC lactylation is dynamically regulated and an important determinant of overall cardiac structure and function. Excessive lactate efflux and consumption by cardiomyocytes may decrease the intracellular lactate level, which is the main cause of reduced α-MHC K1897 lactylation during myocardial injury. Our study reveals that cardiac metabolism directly modulates the sarcomeric structure and function through lactate-dependent modification of α-MHC.
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Affiliation(s)
- Naijin Zhang
- Department of Cardiology, First Hospital of China Medical University, Shenyang, Liaoning, China
- NHC Key Laboratory of Advanced Reproductive Medicine and Fertility, National Health Commission, China Medical University, Shenyang, Liaoning, China
| | - Ying Zhang
- Department of Cardiology, First Hospital of China Medical University, Shenyang, Liaoning, China
- Institute of Health Sciences, China Medical University, Shenyang, Liaoning, China
| | - Jiaqi Xu
- Department of Cardiology, First Hospital of China Medical University, Shenyang, Liaoning, China
| | - Pengbo Wang
- Department of Cardiology, First Hospital of China Medical University, Shenyang, Liaoning, China
| | - Boquan Wu
- Department of Cardiology, First Hospital of China Medical University, Shenyang, Liaoning, China
| | - Saien Lu
- Department of Cardiology, First Hospital of China Medical University, Shenyang, Liaoning, China
| | - Xinxin Lu
- Department of Cardiology, First Hospital of China Medical University, Shenyang, Liaoning, China
| | - Shilong You
- Department of Cardiology, First Hospital of China Medical University, Shenyang, Liaoning, China
| | - Xinyue Huang
- Department of Cardiology, First Hospital of China Medical University, Shenyang, Liaoning, China
| | - Mohan Li
- Department of Cardiology, First Hospital of China Medical University, Shenyang, Liaoning, China
| | - Yuanming Zou
- Department of Cardiology, First Hospital of China Medical University, Shenyang, Liaoning, China
| | - Mengke Liu
- Department of Cardiology, First Hospital of China Medical University, Shenyang, Liaoning, China
| | - Yuanhui Zhao
- Department of Cardiology, First Hospital of China Medical University, Shenyang, Liaoning, China
| | - Guozhe Sun
- Department of Cardiology, First Hospital of China Medical University, Shenyang, Liaoning, China
| | - Wenbin Wang
- Department of Cardiology, First Hospital of China Medical University, Shenyang, Liaoning, China
| | - Danxi Geng
- Department of Cardiology, First Hospital of China Medical University, Shenyang, Liaoning, China
| | - Jingwei Liu
- Key Laboratory of Medical Cell Biology, Ministry of Education, Shenyang, Liaoning, China
- Institute of School of Basic Medicine, China Medical University, Shenyang, Liaoning, China
| | - Liu Cao
- Key Laboratory of Medical Cell Biology, Ministry of Education, Shenyang, Liaoning, China
- Institute of School of Basic Medicine, China Medical University, Shenyang, Liaoning, China
| | - Yingxian Sun
- Department of Cardiology, First Hospital of China Medical University, Shenyang, Liaoning, China.
- Institute of Health Sciences, China Medical University, Shenyang, Liaoning, China.
- Key Laboratory of Environmental Stress and Chronic Disease Control and Prevention, Ministry of Education, China Medical University, Shenyang, Liaoning, China.
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8
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Dietz J, Jacobsen F, Zhuge H, Daya N, Bigot A, Zhang W, Ehrhardt A, Vorgerd M, Ehrke-Schulz E. Muscle Specific Promotors for Gene Therapy - A Comparative Study in Proliferating and Differentiated Cells. J Neuromuscul Dis 2023:JND221574. [PMID: 37270809 DOI: 10.3233/jnd-221574] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
BACKGROUND Depending on the therapy approach and disease background, the heterogeneity of muscular tissues complicates the development of targeted gene therapy, where either expression in all muscle types or restriction to only one muscle type is warranted. Muscle specificity can be achieved using promotors mediating tissue specific and sustained physiological expression in the desired muscle types but limited activity in non-targeted tissue. Several muscle specific promotors have been described, but direct comparisons between them are lacking. OBJECTIVE Here we present a direct comparison of muscle specific Desmin-, MHCK7, microRNA206- and Calpain3 promotor. METHODS To directly compare these muscle specific promotors we utilized transfection of reporter plasmids using an in vitro model based on electrical pulse stimulation (EPS) to provoke sarcomere formation in 2D cell culture for quantification of promotor activities in far differentiated mouse and human myotubes. RESULTS We found that Desmin- and MHCK7 promotors showed stronger reporter gene expression levels in proliferating and differentiated myogenic cell lines than miR206 and CAPN3 promotor. However, Desmin and MHCK7 promotor promoted gene expression also cardiac cells whereas miR206 and CAPN3 promotor expression was restricted to skeletal muscle. CONCLUSIONS Our results provides direct comparison of muscle specific promotors with regard to expression strengths and specificity as this is important feature to avoid undesired transgene expression in non-target muscle cells for a desired therapy approach.
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Affiliation(s)
- Julienne Dietz
- Department of Human Medicine, Institute of Virology and Microbiology, Center for Biomedical Education and Research (ZBAF), Faculty of Health, Witten/Herdecke University, Witten, Germany
- Department of Neurology, University Hospital Bergmannsheil, Heimer Institute for Muscle Research, Bochum, Germany
| | - Frank Jacobsen
- Department of Neurology, University Hospital Bergmannsheil, Heimer Institute for Muscle Research, Bochum, Germany
| | - Heidi Zhuge
- Department of Neurology, University Hospital Bergmannsheil, Heimer Institute for Muscle Research, Bochum, Germany
| | - Nassam Daya
- Department of Neurology, University Hospital Bergmannsheil, Heimer Institute for Muscle Research, Bochum, Germany
| | - Anne Bigot
- Sorbonne Université, Inserm, Institut de Myologie, Centre de Recherche en Myologie, F-75013 Paris, France
| | - Wenli Zhang
- Department of Human Medicine, Institute of Virology and Microbiology, Center for Biomedical Education and Research (ZBAF), Faculty of Health, Witten/Herdecke University, Witten, Germany
| | - Anja Ehrhardt
- Department of Human Medicine, Institute of Virology and Microbiology, Center for Biomedical Education and Research (ZBAF), Faculty of Health, Witten/Herdecke University, Witten, Germany
| | - Matthias Vorgerd
- Department of Neurology, University Hospital Bergmannsheil, Heimer Institute for Muscle Research, Bochum, Germany
| | - Eric Ehrke-Schulz
- Department of Human Medicine, Institute of Virology and Microbiology, Center for Biomedical Education and Research (ZBAF), Faculty of Health, Witten/Herdecke University, Witten, Germany
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9
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Grande V, Schuld J, van der Ven PFM, Gruss OJ, Fürst DO. Filamin-A-interacting protein 1 (FILIP1) is a dual compartment protein linking myofibrils and microtubules during myogenic differentiation and upon mechanical stress. Cell Tissue Res 2023:10.1007/s00441-023-03776-4. [PMID: 37178194 DOI: 10.1007/s00441-023-03776-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Accepted: 04/19/2023] [Indexed: 05/15/2023]
Abstract
Variations in the gene encoding filamin-A-interacting protein 1 (FILIP1) were identified to be associated with a combination of neurological and muscular symptoms. While FILIP1 was shown to regulate motility of brain ventricular zone cells, a process important for corticogenesis, the function of the protein in muscle cells has been less well characterized. The expression of FILIP1 in regenerating muscle fibres predicted a role in early muscle differentiation. Here we analysed expression and localization of FILIP1 and its binding partners filamin-C (FLNc) and microtubule plus-end-binding protein EB3 in differentiating cultured myotubes and adult skeletal muscle. Prior to the development of cross-striated myofibrils, FILIP1 is associated with microtubules and colocalizes with EB3. During further myofibril maturation its localization changes, and FILIP1 localizes to myofibrillar Z-discs together with the actin-binding protein FLNc. Forced contractions of myotubes by electrical pulse stimulation (EPS) induce focal disruptions in myofibrils and translocation of both proteins from Z-discs to these lesions, suggesting a role in induction and/or repair of these structures. The immediate proximity of tyrosylated, dynamic microtubules and EB3 to lesions implies that also these play a role in these processes. This implication is supported by the fact that in nocodazole-treated myotubes that lack functional microtubules, the number of lesions induced by EPS is significantly reduced. In summary, we here show that FILIP1 is a cytolinker protein that is associated with both microtubules and actin filaments, and might play a role in the assembly of myofibrils and their stabilization upon mechanical stress to protect them from damage.
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Affiliation(s)
- Valentina Grande
- Institute for Cell Biology, University of Bonn, Ulrich-Haberland-Str. 61a, 53121, Bonn, Germany
| | - Julia Schuld
- Institute for Cell Biology, University of Bonn, Ulrich-Haberland-Str. 61a, 53121, Bonn, Germany
| | - Peter F M van der Ven
- Institute for Cell Biology, University of Bonn, Ulrich-Haberland-Str. 61a, 53121, Bonn, Germany
| | - Oliver J Gruss
- Institute of Genetics, University of Bonn, Karlrobert-Kreiten-Str. 13, 53115, Bonn, Germany
| | - Dieter O Fürst
- Institute for Cell Biology, University of Bonn, Ulrich-Haberland-Str. 61a, 53121, Bonn, Germany.
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10
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Linke WA. Stretching the story of titin and muscle function. J Biomech 2023; 152:111553. [PMID: 36989971 DOI: 10.1016/j.jbiomech.2023.111553] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Accepted: 03/14/2023] [Indexed: 03/29/2023]
Abstract
The discovery of the giant protein titin, also known as connectin, dates almost half a century back. In this review, I recapitulate major advances in the discovery of the titin filaments and the recognition of their properties and function until today. I briefly discuss how our understanding of the layout and interactions of titin in muscle sarcomeres has evolved and review key facts about the titin sequence at the gene (TTN) and protein levels. I also touch upon properties of titin important for the stability of the contractile units and the assembly and maintenance of sarcomeric proteins. The greater part of my discussion centers around the mechanical function of titin in skeletal muscle. I cover milestones of research on titin's role in stretch-dependent passive tension development, recollect the reasons behind the enormous elastic diversity of titin, and provide an update on the molecular mechanisms of titin elasticity, details of which are emerging even now. I reflect on current knowledge of how muscle fibers behave mechanically if titin stiffness is removed and how titin stiffness can be dynamically regulated, such as by posttranslational modifications or calcium binding. Finally, I highlight novel and exciting, but still controversially discussed, insight into the role titin plays in active tension development, such as length-dependent activation and contraction from longer muscle lengths.
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Affiliation(s)
- Wolfgang A Linke
- Institute of Physiology II, University of Münster, Germany; Clinic for Cardiology and Pneumology, University Medical Center Göttingen, Germany; German Centre for Cardiovascular Research, Berlin, Germany.
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11
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Less fatiguability in eccentric than concentric repetitive maximal muscle contractions. Eur J Appl Physiol 2023:10.1007/s00421-023-05178-4. [PMID: 36934359 DOI: 10.1007/s00421-023-05178-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Accepted: 03/07/2023] [Indexed: 03/20/2023]
Abstract
PURPOSE Changes in elbow flexion torque and biceps brachii electromyogram (EMG) activity over 30 repetitive maximal voluntary concentric-only (CON-only), eccentric-only (ECC-only), and alternative concentric and eccentric (CON-ECC, 30 concentric + 30 eccentric) contractions were examined to compare their muscle fatigue profiles. METHODS Fifteen healthy young men performed CON-only, ECC-only and CON-ECC in their maximal effort between 10° and 100° elbow flexion on an isokinetic dynamometer at an angular velocity of 30°/s with a 3-s rest between contractions in a randomised order with ≥ 3 days between conditions. Changes in torque and EMG over the repeated contractions and maximal voluntary isometric contraction (MVC-ISO) torque with EMG before the first contraction and immediately after the last contraction were compared among conditions by two-way repeated measures analysis of variance. RESULTS The torque decreased (p < 0.01) from the first to 30th contraction in CON-only (- 49.5 ± 11.0%), ECC-only (- 32.2 ± 7.4%), and concentric (- 62.3 ± 8.7%) as well as eccentric phase (- 58.9 ± 9.3%) in CON-ECC (- 46.0 ± 12.3% overall). The magnitude of the decrease in the torque was greater (p < 0.01) for the CON-only than ECC-only, and the concentric than an eccentric phase in the CON-ECC. However, MVC-ISO torque decreased (p < 0.01) similarly after CON-only (- 42.9 ± 13.8%) and ECC-only (- 40.1 ± 9.2%), which was smaller (p < 0.01) than CON-ECC (- 56.8 ± 9.2%). EMG over contractions decreased (p < 0.01) for all conditions similarly from the first to the last contraction (- 28.5 ± 26.8%), and EMG in MVC-ISO also decreased similarly for all conditions (- 24.7 ± 35.8%). CONCLUSION These results suggest greater fatigue resistance in repetitive maximal eccentric than concentric contractions, but the fatigue assessed by MVC-ISO does not show it.
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12
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Titin activates myosin filaments in skeletal muscle by switching from an extensible spring to a mechanical rectifier. Proc Natl Acad Sci U S A 2023; 120:e2219346120. [PMID: 36812205 PMCID: PMC9992839 DOI: 10.1073/pnas.2219346120] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/24/2023] Open
Abstract
Titin is a molecular spring in parallel with myosin motors in each muscle half-sarcomere, responsible for passive force development at sarcomere length (SL) above the physiological range (>2.7 μm). The role of titin at physiological SL is unclear and is investigated here in single intact muscle cells of the frog (Rana esculenta), by combining half-sarcomere mechanics and synchrotron X-ray diffraction in the presence of 20 μM para-nitro-blebbistatin, which abolishes the activity of myosin motors and maintains them in the resting state even during activation of the cell by electrical stimulation. We show that, during cell activation at physiological SL, titin in the I-band switches from an SL-dependent extensible spring (OFF-state) to an SL-independent rectifier (ON-state) that allows free shortening while resisting stretch with an effective stiffness of ~3 pN nm-1 per half-thick filament. In this way, I-band titin efficiently transmits any load increase to the myosin filament in the A-band. Small-angle X-ray diffraction signals reveal that, with I-band titin ON, the periodic interactions of A-band titin with myosin motors alter their resting disposition in a load-dependent manner, biasing the azimuthal orientation of the motors toward actin. This work sets the stage for future investigations on scaffold and mechanosensing-based signaling functions of titin in health and disease.
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13
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Loreau V, Rees R, Chan EH, Taxer W, Gregor K, Mußil B, Pitaval C, Luis NM, Mangeol P, Schnorrer F, Görlich D. A nanobody toolbox to investigate localisation and dynamics of Drosophila titins and other key sarcomeric proteins. eLife 2023; 12:79343. [PMID: 36645120 PMCID: PMC9886281 DOI: 10.7554/elife.79343] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Accepted: 12/16/2022] [Indexed: 01/17/2023] Open
Abstract
Measuring the positions and dynamics of proteins in intact tissues or whole animals is key to understanding protein function. However, to date, this is challenging, as the accessibility of large antibodies to dense tissues is often limited, and fluorescent proteins inserted close to a domain of interest may affect protein function. These complications apply in particular to muscle sarcomeres, arguably one of the most protein-dense assemblies in nature, which complicates studying sarcomere morphogenesis at molecular resolution. Here, we introduce a toolbox of nanobodies recognising various domains of the two Drosophila titin homologs, Sallimus and Projectin, as well as the key sarcomeric proteins Obscurin, α-Actinin, and Zasp52. We verified the superior labelling qualities of our nanobodies in muscle tissue as compared to antibodies. By applying our toolbox to larval muscles, we found a gigantic Sallimus isoform stretching more than 2 µm to bridge the sarcomeric I-band, while Projectin covers almost the entire myosin filaments in a polar orientation. Transgenic expression of tagged nanobodies confirmed their high affinity-binding without affecting target protein function. Finally, adding a degradation signal to anti-Sallimus nanobodies suggested that it is difficult to fully degrade Sallimus in mature sarcomeres; however, expression of these nanobodies caused developmental lethality. These results may inspire the generation of similar toolboxes for other large protein complexes in Drosophila or mammals.
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Affiliation(s)
- Vincent Loreau
- Turing Centre for Living Systems, Aix-Marseille University, CNRS, IDBMMarseilleFrance
| | - Renate Rees
- Department of Cellular Logistics, Max Planck Institute for Multidisciplinary SciencesGöttingenGermany
| | - Eunice HoYee Chan
- Turing Centre for Living Systems, Aix-Marseille University, CNRS, IDBMMarseilleFrance
| | - Waltraud Taxer
- Department of Cellular Logistics, Max Planck Institute for Multidisciplinary SciencesGöttingenGermany
| | - Kathrin Gregor
- Department of Cellular Logistics, Max Planck Institute for Multidisciplinary SciencesGöttingenGermany
| | - Bianka Mußil
- Department of Cellular Logistics, Max Planck Institute for Multidisciplinary SciencesGöttingenGermany
| | - Christophe Pitaval
- Turing Centre for Living Systems, Aix-Marseille University, CNRS, IDBMMarseilleFrance
| | - Nuno Miguel Luis
- Turing Centre for Living Systems, Aix-Marseille University, CNRS, IDBMMarseilleFrance
| | - Pierre Mangeol
- Turing Centre for Living Systems, Aix-Marseille University, CNRS, IDBMMarseilleFrance
| | - Frank Schnorrer
- Turing Centre for Living Systems, Aix-Marseille University, CNRS, IDBMMarseilleFrance
| | - Dirk Görlich
- Department of Cellular Logistics, Max Planck Institute for Multidisciplinary SciencesGöttingenGermany
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14
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Zhu K, Bao X, Wang Y, Lu T, Zhang L. Human induced pluripotent stem cell (hiPSC)-derived cardiomyocyte modelling of cardiovascular diseases for natural compound discovery. Biomed Pharmacother 2023; 157:113970. [PMID: 36371854 DOI: 10.1016/j.biopha.2022.113970] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Revised: 10/29/2022] [Accepted: 11/01/2022] [Indexed: 11/11/2022] Open
Abstract
Cardiovascular disease (CVD) remains the leading cause of death worldwide. Natural compounds extracted from medicinal plants characterized by diverse biological activities and low toxicity or side effects, are increasingly taking center stage in the search for new drugs. Currently, preclinical evaluation of natural products relies mainly on the use of immortalized cell lines of human origin or animal models. Increasing evidence indicates that cardiomyopathy models based on immortalized cell lines do not recapitulate pathogenic phenotypes accurately and a substantial physiological discrepancy between animals and humans casts doubt on the clinical relevance of animal models for these studies. The newly developed human induced pluripotent stem cell (hiPSC) technology in combination with highly-efficient cardiomyocyte differentiation methods provides an ideal tool for modeling human cardiomyopathies in vitro. Screening of drugs, especially screening of natural products, based on these models has been widely used and has shown that evaluation in such models can recapitulate important aspects of the physiological properties of drugs. The purpose of this review is to provide information on the latest developments in this area of research and to help researchers perform screening of natural products using the hiPSC-CM platform.
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Affiliation(s)
- Keyang Zhu
- Zhejiang Key Laboratory of Pathophysiology, School of Public Health, School of Medicine, Ningbo University, Ningbo, Zhejiang 315211, PR China
| | - Xiaoming Bao
- Department of Cardiology, Hwa Mei Hospital, University of Chinese Academy of Sciences, Ningbo, Zhejiang, PR China; Department of Global Health, Ningbo Institute of Life and Health Industry, University of Chinese Academy of Sciences, Ningbo, Zhejiang, PR China
| | - Yingchao Wang
- Innovation Institute for Artificial Intelligence in Medicine of Zhejiang University, Hangzhou, Zhejiang, PR China
| | - Ting Lu
- Clinical Research Center of The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, PR China.
| | - Ling Zhang
- College of Life Science, Zhejiang Chinese Medical University, Hangzhou, PR China.
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15
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Noureddine M, Gehmlich K. Structural and signaling proteins in the Z-disk and their role in cardiomyopathies. Front Physiol 2023; 14:1143858. [PMID: 36935760 PMCID: PMC10017460 DOI: 10.3389/fphys.2023.1143858] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Accepted: 02/21/2023] [Indexed: 03/06/2023] Open
Abstract
The sarcomere is the smallest functional unit of muscle contraction. It is delineated by a protein-rich structure known as the Z-disk, alternating with M-bands. The Z-disk anchors the actin-rich thin filaments and plays a crucial role in maintaining the mechanical stability of the cardiac muscle. A multitude of proteins interact with each other at the Z-disk and they regulate the mechanical properties of the thin filaments. Over the past 2 decades, the role of the Z-disk in cardiac muscle contraction has been assessed widely, however, the impact of genetic variants in Z-disk proteins has still not been fully elucidated. This review discusses the various Z-disk proteins (alpha-actinin, filamin C, titin, muscle LIM protein, telethonin, myopalladin, nebulette, and nexilin) and Z-disk-associated proteins (desmin, and obscurin) and their role in cardiac structural stability and intracellular signaling. This review further explores how genetic variants of Z-disk proteins are linked to inherited cardiac conditions termed cardiomyopathies.
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Affiliation(s)
- Maya Noureddine
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
- *Correspondence: Maya Noureddine, ; Katja Gehmlich,
| | - Katja Gehmlich
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
- Cardiovascular Medicine, Radcliffe Department of Medicine and British Heart Foundation Centre of Research Excellence Oxford, University of Oxford, Oxford, United Kingdom
- *Correspondence: Maya Noureddine, ; Katja Gehmlich,
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16
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Hessel AL, Ma W, Mazara N, Rice PE, Nissen D, Gong H, Kuehn M, Irving T, Linke WA. Titin force in muscle cells alters lattice order, thick and thin filament protein formation. Proc Natl Acad Sci U S A 2022; 119:e2209441119. [PMID: 36409887 PMCID: PMC9860331 DOI: 10.1073/pnas.2209441119] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Accepted: 10/25/2022] [Indexed: 11/22/2022] Open
Abstract
Skeletal muscle force production is increased at longer compared to shorter muscle lengths because of length-dependent priming of thick filament proteins in the contractile unit before contraction. Using small-angle X-ray diffraction in combination with a mouse model that specifically cleaves the stretch-sensitive titin protein, we found that titin cleavage diminished the length-dependent priming of the thick filament. Strikingly, a titin-sensitive, length-dependent priming was also present in thin filaments, which seems only possible via bridge proteins between thick and thin filaments in resting muscle, potentially myosin-binding protein C. We further show that these bridges can be forcibly ruptured via high-speed stretches. Our results advance a paradigm shift to the fundamental regulation of length-dependent priming, with titin as the key driver.
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Affiliation(s)
- Anthony L. Hessel
- Institute of Physiology II, University of Muenster, Muenster, 48149Germany
| | - Weikang Ma
- BioCAT, Department of Biology, Illinois Institute of Technology, Chicago, IL 60616
| | - Nicole Mazara
- School of Kinesiology, University of British Columbia, Vancouver, CanadaV6T 1Z1
| | - Paige E. Rice
- Department of Biological Sciences, Northern Arizona University, FlagstaffAZ 86011
| | - Devin Nissen
- BioCAT, Department of Biology, Illinois Institute of Technology, Chicago, IL 60616
| | - Henry Gong
- BioCAT, Department of Biology, Illinois Institute of Technology, Chicago, IL 60616
| | - Michel Kuehn
- Institute of Physiology II, University of Muenster, Muenster, 48149Germany
| | - Thomas Irving
- BioCAT, Department of Biology, Illinois Institute of Technology, Chicago, IL 60616
| | - Wolfgang A. Linke
- Institute of Physiology II, University of Muenster, Muenster, 48149Germany
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17
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Amrute-Nayak M, Gand LV, Khan B, Holler T, Kefalakes E, Kosanke M, Kraft T, Nayak A. SENP7 deSUMOylase-governed transcriptional program coordinates sarcomere assembly and is targeted in muscle atrophy. Cell Rep 2022; 41:111702. [DOI: 10.1016/j.celrep.2022.111702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Revised: 08/16/2022] [Accepted: 10/31/2022] [Indexed: 11/23/2022] Open
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18
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LIM CHANGHYUN, NUNES EVERSONA, CURRIER BRADS, MCLEOD JONATHANC, THOMAS AARONCQ, PHILLIPS STUARTM. An Evidence-Based Narrative Review of Mechanisms of Resistance Exercise-Induced Human Skeletal Muscle Hypertrophy. Med Sci Sports Exerc 2022; 54:1546-1559. [PMID: 35389932 PMCID: PMC9390238 DOI: 10.1249/mss.0000000000002929] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Skeletal muscle plays a critical role in physical function and metabolic health. Muscle is a highly adaptable tissue that responds to resistance exercise (RE; loading) by hypertrophying, or during muscle disuse, RE mitigates muscle loss. Resistance exercise training (RET)-induced skeletal muscle hypertrophy is a product of external (e.g., RE programming, diet, some supplements) and internal variables (e.g., mechanotransduction, ribosomes, gene expression, satellite cells activity). RE is undeniably the most potent nonpharmacological external variable to stimulate the activation/suppression of internal variables linked to muscular hypertrophy or countering disuse-induced muscle loss. Here, we posit that despite considerable research on the impact of external variables on RET and hypertrophy, internal variables (i.e., inherent skeletal muscle biology) are dominant in regulating the extent of hypertrophy in response to external stimuli. Thus, identifying the key internal skeletal muscle-derived variables that mediate the translation of external RE variables will be pivotal to determining the most effective strategies for skeletal muscle hypertrophy in healthy persons. Such work will aid in enhancing function in clinical populations, slowing functional decline, and promoting physical mobility. We provide up-to-date, evidence-based perspectives of the mechanisms regulating RET-induced skeletal muscle hypertrophy.
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Affiliation(s)
- CHANGHYUN LIM
- Department of Kinesiology, McMaster University, Hamilton, Ontario, CANADA
| | - EVERSON A. NUNES
- Department of Kinesiology, McMaster University, Hamilton, Ontario, CANADA
- Department of Physiological Science, Federal University of Santa Catarina, Florianópolis, Santa-Catarina, BRAZIL
| | - BRAD S. CURRIER
- Department of Kinesiology, McMaster University, Hamilton, Ontario, CANADA
| | - JONATHAN C. MCLEOD
- Department of Kinesiology, McMaster University, Hamilton, Ontario, CANADA
| | - AARON C. Q. THOMAS
- Department of Kinesiology, McMaster University, Hamilton, Ontario, CANADA
| | - STUART M. PHILLIPS
- Department of Kinesiology, McMaster University, Hamilton, Ontario, CANADA
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19
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Exploring the Potential of Symmetric Exon Deletion to Treat Non-Ischemic Dilated Cardiomyopathy by Removing Frameshift Mutations in TTN. Genes (Basel) 2022; 13:genes13061093. [PMID: 35741855 PMCID: PMC9222585 DOI: 10.3390/genes13061093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Revised: 05/30/2022] [Accepted: 06/10/2022] [Indexed: 11/17/2022] Open
Abstract
Non-ischemic dilated cardiomyopathy (DCM) is one of the most frequent pathologies requiring cardiac transplants. Even though the etiology of this disease is complex, frameshift mutations in the giant sarcomeric protein Titin could explain up to 25% of the familial and 18% of the sporadic cases of DCM. Many studies have shown the potential of genome editing using CRISPR/Cas9 to correct truncating mutations in sarcomeric proteins and have established the grounds for myoediting. However, these therapies are still in an immature state, with only few studies showing an efficient treatment of cardiac diseases. This publication hypothesizes that the Titin (TTN)-specific gene structure allows the application of myoediting approaches in a broad range of locations to reframe TTNtvvariants and to treat DCM patients. Additionally, to pave the way for the generation of efficient myoediting approaches for DCM, we screened and selected promising target locations in TTN. We conceptually explored the deletion of symmetric exons as a therapeutic approach to restore TTN’s reading frame in cases of frameshift mutations. We identified a set of 94 potential candidate exons of TTN that we consider particularly suitable for this therapeutic deletion. With this study, we aim to contribute to the development of new therapies to efficiently treat titinopathies and other diseases caused by mutations in genes encoding proteins with modular structures, e.g., Obscurin.
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20
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The Mechanisms of Thin Filament Assembly and Length Regulation in Muscles. Int J Mol Sci 2022; 23:ijms23105306. [PMID: 35628117 PMCID: PMC9140763 DOI: 10.3390/ijms23105306] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Revised: 05/05/2022] [Accepted: 05/06/2022] [Indexed: 02/01/2023] Open
Abstract
The actin containing tropomyosin and troponin decorated thin filaments form one of the crucial components of the contractile apparatus in muscles. The thin filaments are organized into densely packed lattices interdigitated with myosin-based thick filaments. The crossbridge interactions between these myofilaments drive muscle contraction, and the degree of myofilament overlap is a key factor of contractile force determination. As such, the optimal length of the thin filaments is critical for efficient activity, therefore, this parameter is precisely controlled according to the workload of a given muscle. Thin filament length is thought to be regulated by two major, but only partially understood mechanisms: it is set by (i) factors that mediate the assembly of filaments from monomers and catalyze their elongation, and (ii) by factors that specify their length and uniformity. Mutations affecting these factors can alter the length of thin filaments, and in human cases, many of them are linked to debilitating diseases such as nemaline myopathy and dilated cardiomyopathy.
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21
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Hou Q, Zhong Y, Liu L, Wu L, Liu J. Construction of a lung adenocarcinoma prognostic model based on N6-methyl-adenosine-related long noncoding RNA and screening of potential drugs based on this model. Anticancer Drugs 2022; 33:371-383. [PMID: 35213857 PMCID: PMC8912967 DOI: 10.1097/cad.0000000000001277] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Revised: 02/03/2022] [Accepted: 02/03/2022] [Indexed: 11/25/2022]
Abstract
Lung adenocarcinoma (LUAD) has a high mortality rate. N6-methyl-adenosine (m6A)-related long noncoding RNA (lncRNA) is associated with tumor prognosis. Our objective was to construct an m6A-related lncRNA prognostic model and screen potential drugs for the treatment of LUAD. The LUAD sequencing data were randomly divided into Train and Test cohorts. In the Train group, the LASSO Cox regression was used to construct the m6A-related lncRNA prognostic model. The LUAD tumor immune dysfunction and exclusion model was used to evaluate immunotherapy efficacy in LUAD. The 'pRRophetic' package was utilized to screen potential drugs for the treatment of LUAD. Eleven m6A-related lncRNAs were identified by LASSO Cox regression and were used to construct the risk model to calculate sample risk scores. Patients were divided into high- and low-risk groups based on their median risk scores. The LUAD data of The Cancer Genome Atlas database showed that the overall survival (OS) of the high-risk group was significantly lower than that of the low-risk group in both cohorts. Multivariate Cox regression analysis showed that this risk model could serve as an independent prognostic factor of LUAD, and receiver operating characteristic curves suggested that m6A-related lncRNA prognostic signature has a good ability in predicting OS. Finally, nine potential drugs for LUAD treatment were screened based on this prognostic model. The prognostic model constructed based on the m6A-related lncRNAs facilitated prognosis prediction in LUAD patients. The screened therapeutic agents have potential application values and provide a reference for the clinical treatment of LUAD.
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Affiliation(s)
- Qinghua Hou
- Department of Clinical Medicine, Weifang Medical University, Weifang
| | | | - Linzhuang Liu
- Thoracic Surgery, Peking University Shenzhen Hospital, Shenzhen, China
| | - Liusheng Wu
- Thoracic Surgery, Peking University Shenzhen Hospital, Shenzhen, China
| | - Jixian Liu
- Thoracic Surgery, Peking University Shenzhen Hospital, Shenzhen, China
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22
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Methawasin M, Farman GP, Granzier-Nakajima S, Strom J, Kiss B, Smith JE, Granzier H. Shortening the thick filament by partial deletion of titin's C-zone alters cardiac function by reducing the operating sarcomere length range. J Mol Cell Cardiol 2022; 165:103-114. [PMID: 35031281 PMCID: PMC8940690 DOI: 10.1016/j.yjmcc.2022.01.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Revised: 01/06/2022] [Accepted: 01/07/2022] [Indexed: 10/19/2022]
Abstract
Titin's C-zone is an inextensible segment in titin, comprised of 11 super-repeats and located in the cMyBP-C-containing region of the thick filament. Previously we showed that deletion of titin's super-repeats C1 and C2 (TtnΔC1-2 model) results in shorter thick filaments and contractile dysfunction of the left ventricular (LV) chamber but that unexpectedly LV diastolic stiffness is normal. Here we studied the contraction-relaxation kinetics from the time-varying elastance of the LV and intact cardiomyocyte, cellular work loops of intact cardiomyocytes, Ca2+ transients, cross-bridge kinetics, and myofilament Ca2+ sensitivity. Intact cardiomyocytes of TtnΔC1-2 mice exhibit systolic dysfunction and impaired relaxation. The time-varying elastance at both LV and single-cell levels showed that activation kinetics are normal in TtnΔC1-2 mice, but that relaxation is slower. The slowed relaxation is, in part, attributable to an increased myofilament Ca2+ sensitivity and slower early Ca2+ reuptake. Cross-bridge dynamics showed that cross-bridge kinetics are normal but that the number of force-generating cross-bridges is reduced. In vivo sarcomere length (SL) measurements revealed that in TtnΔC1-2 mice the operating SL range of the LV is shifted towards shorter lengths. This normalizes the apparent cell and LV diastolic stiffness but further reduces systolic force as systole occurs further down on the ascending limb of the force-SL relation. We propose that the reduced working SLs reflect titin's role in regulating diastolic stiffness by altering the number of sarcomeres in series. Overall, our study reveals that thick filament length regulation by titin's C-zone is critical for normal cardiac function.
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Affiliation(s)
- Mei Methawasin
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85721, United States of America.
| | - Gerrie P Farman
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85721, United States of America
| | - Shawtaroh Granzier-Nakajima
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85721, United States of America
| | - Joshua Strom
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85721, United States of America
| | - Balazs Kiss
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85721, United States of America
| | - John E Smith
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85721, United States of America
| | - Henk Granzier
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85721, United States of America.
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23
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Mechanobiology of muscle and myofibril morphogenesis. Cells Dev 2021; 168:203760. [PMID: 34863916 DOI: 10.1016/j.cdev.2021.203760] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Revised: 11/22/2021] [Accepted: 11/22/2021] [Indexed: 01/05/2023]
Abstract
Muscles generate forces for animal locomotion. The contractile apparatus of muscles is the sarcomere, a highly regular array of large actin and myosin filaments linked by gigantic titin springs. During muscle development many sarcomeres assemble in series into long periodic myofibrils that mechanically connect the attached skeleton elements. Thus, ATP-driven myosin forces can power movement of the skeleton. Here we review muscle and myofibril morphogenesis, with a particular focus on their mechanobiology. We describe recent progress on the molecular structure of sarcomeres and their mechanical connections to the skeleton. We discuss current models predicting how tension coordinates the assembly of key sarcomeric components to periodic myofibrils that then further mature during development. This requires transcriptional feedback mechanisms that may help to coordinate myofibril assembly and maturation states with the transcriptional program. To fuel the varying energy demands of muscles we also discuss the close mechanical interactions of myofibrils with mitochondria and nuclei to optimally support powerful or enduring muscle fibers.
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24
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Lohanadan K, Molt S, Dierck F, van der Ven PFM, Frey N, Höhfeld J, Fürst DO. Isoform-specific functions of synaptopodin-2 variants in cytoskeleton stabilization and autophagy regulation in muscle under mechanical stress. Exp Cell Res 2021; 408:112865. [PMID: 34637763 DOI: 10.1016/j.yexcr.2021.112865] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 10/01/2021] [Accepted: 10/03/2021] [Indexed: 11/17/2022]
Abstract
Protein homeostasis (proteostasis) in multicellular organisms depends on the maintenance of force-bearing and force-generating cellular structures. Within myofibrillar Z-discs of striated muscle, isoforms of synaptopodin-2 (SYNPO2/myopodin) act as adapter proteins that are engaged in proteostasis of the actin-crosslinking protein filamin C (FLNc) under mechanical stress. SYNPO2 directly binds F-actin, FLNc and α-actinin and thus contributes to the architectural features of the actin cytoskeleton. By its association with autophagy mediating proteins, i.e. BAG3 and VPS18, SYNPO2 is also engaged in protein quality control and helps to target mechanical unfolded and damaged FLNc for degradation. Here we show that deficiency of all SYNPO2-isoforms in myotubes leads to decreased myofibrillar stability and deregulated autophagy under mechanical stress. In addition, isoform-specific proteostasis functions were revealed. The PDZ-domain containing variant SYNPO2b and the shorter, PDZ-less isoform SYNPO2e both localize to Z-discs. Yet, SYNPO2e is less stably associated with the Z-disc than SYNPO2b, and is dynamically transferred into FLNc-containing myofibrillar lesions under mechanical stress. SYNPO2e also recruits BAG3 into these lesions via interaction with the WW domain of BAG3. Our data provide evidence for a role of myofibrillar lesions as a transient quality control compartment essential to prevent and repair contraction-induced myofibril damage in muscle and indicate an important coordinating activity for SYNPO2 therein.
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Affiliation(s)
- Keerthika Lohanadan
- Department of Molecular Cell Biology, Institute for Cell Biology, University of Bonn, 53121 Bonn, Germany
| | - Sibylle Molt
- Department of Molecular Cell Biology, Institute for Cell Biology, University of Bonn, 53121 Bonn, Germany
| | - Franziska Dierck
- Department of Internal Medicine III, University Medical Center Schleswig-Holstein, Campus Kiel, 24105 Kiel, Germany
| | - Peter F M van der Ven
- Department of Molecular Cell Biology, Institute for Cell Biology, University of Bonn, 53121 Bonn, Germany
| | - Norbert Frey
- Department of Internal Medicine III, University Medical Center Schleswig-Holstein, Campus Kiel, 24105 Kiel, Germany; German Centre for Cardiovascular Research, Partner Site Heidelberg, 69120 Heidelberg, Germany
| | - Jörg Höhfeld
- Department of Molecular Cell Biology, Institute for Cell Biology, University of Bonn, 53121 Bonn, Germany
| | - Dieter O Fürst
- Department of Molecular Cell Biology, Institute for Cell Biology, University of Bonn, 53121 Bonn, Germany.
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25
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Increased Expression of N2BA Titin Corresponds to More Compliant Myofibrils in Athlete's Heart. Int J Mol Sci 2021; 22:ijms222011110. [PMID: 34681770 PMCID: PMC8537917 DOI: 10.3390/ijms222011110] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Revised: 10/07/2021] [Accepted: 10/10/2021] [Indexed: 12/22/2022] Open
Abstract
Long-term exercise induces physiological cardiac adaptation, a condition referred to as athlete’s heart. Exercise tolerance is known to be associated with decreased cardiac passive stiffness. Passive stiffness of the heart muscle is determined by the giant elastic protein titin. The adult cardiac muscle contains two titin isoforms: the more compliant N2BA and the stiffer N2B. Titin-based passive stiffness may be controlled by altering the expression of the different isoforms or via post-translational modifications such as phosphorylation. Currently, there is very limited knowledge about titin’s role in cardiac adaptation during long-term exercise. Our aim was to determine the N2BA/N2B ratio and post-translational phosphorylation of titin in the left ventricle and to correlate the changes with the structure and transverse stiffness of cardiac sarcomeres in a rat model of an athlete’s heart. The athlete’s heart was induced by a 12-week-long swim-based training. In the exercised myocardium the N2BA/N2B ratio was significantly increased, Ser11878 of the PEVK domain was hypophosphorlyated, and the sarcomeric transverse elastic modulus was reduced. Thus, the reduced passive stiffness in the athlete’s heart is likely caused by a shift towards the expression of the longer cardiac titin isoform and a phosphorylation-induced softening of the PEVK domain which is manifested in a mechanical rearrangement locally, within the cardiac sarcomere.
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Overexpression of human BAG3 P209L in mice causes restrictive cardiomyopathy. Nat Commun 2021; 12:3575. [PMID: 34117258 PMCID: PMC8196106 DOI: 10.1038/s41467-021-23858-7] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Accepted: 05/20/2021] [Indexed: 12/15/2022] Open
Abstract
An amino acid exchange (P209L) in the HSPB8 binding site of the human co-chaperone BAG3 gives rise to severe childhood cardiomyopathy. To phenocopy the disease in mice and gain insight into its mechanisms, we generated humanized transgenic mouse models. Expression of human BAG3P209L-eGFP in mice caused Z-disc disintegration and formation of protein aggregates. This was accompanied by massive fibrosis resulting in early-onset restrictive cardiomyopathy with increased mortality as observed in patients. RNA-Seq and proteomics revealed changes in the protein quality control system and increased autophagy in hearts from hBAG3P209L-eGFP mice. The mutation renders hBAG3P209L less soluble in vivo and induces protein aggregation, but does not abrogate hBAG3 binding properties. In conclusion, we report a mouse model mimicking the human disease. Our data suggest that the disease mechanism is due to accumulation of hBAG3P209L and mouse Bag3, causing sequestering of components of the protein quality control system and autophagy machinery leading to sarcomere disruption. An amino acid exchange (P209L) in the human co-chaperone BAG3 gives rise to severe childhood restrictive cardiomyopathy. Here the authors describe humanized transgenic mouse models which phenocopy the disease and provide insight into the pathogenic mechanisms.
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McDermott H, Henderson A, Robinson HK, Heaver R, Halahakoon C, Cox H, Naik S. Novel compound heterozygous TTN variants as a cause of severe neonatal congenital contracture syndrome without cardiac involvement diagnosed with rapid trio exome sequencing. Neuromuscul Disord 2021; 31:783-787. [PMID: 34303570 DOI: 10.1016/j.nmd.2021.05.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Revised: 04/19/2021] [Accepted: 05/17/2021] [Indexed: 10/21/2022]
Abstract
This report focuses on a case of severe congenital myopathy with arthrogryposis without cardiac involvement due to compound heterozygous variants in the TTN gene. The proband presented with severe axial hypotonia, arthrogryposis and severe respiratory insufficiency with ventilator dependence. Electromyogram was abnormal with absent motor responses but preserved sensory nerve responses. Rapid gene-agnostic trio exome sequencing detected novel compound heterozygous variants in the TTN gene. One variant is a truncating frameshift located in the meta-transcript only exon 195. The other variant is a nonsense variant in exon 327 which affects all recognised post-natal transcripts apart from one. This case presents with a severe phenotype and adds to the expanding known variants associated with autosomal recessive titinopathy. It also demonstrates the utility of rapid trio exome sequencing when used early in the clinical course.
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Affiliation(s)
- Helen McDermott
- Clinical Genetics Department, Birmingham Women's and Children's NHS Foundation Trust, Birmingham, UK.
| | - Amy Henderson
- Neonatal Unit, New Cross Hospital, Royal Wolverhampton NHS Trust, Wolverhampton, UK
| | - Hannah K Robinson
- Exeter Genomics Laboratory, Royal Devon and Exeter NHS Foundation Trust, Exeter, UK
| | - Richard Heaver
- Neonatal Unit, New Cross Hospital, Royal Wolverhampton NHS Trust, Wolverhampton, UK
| | | | - Helen Cox
- Clinical Genetics Department, Birmingham Women's and Children's NHS Foundation Trust, Birmingham, UK
| | - Swati Naik
- Clinical Genetics Department, Birmingham Women's and Children's NHS Foundation Trust, Birmingham, UK
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28
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Jiang X, Chen Y, Liu X, Ye L, Yu M, Shen Z, Lei W, Hu S. Uncovering Inherited Cardiomyopathy With Human Induced Pluripotent Stem Cells. Front Cell Dev Biol 2021; 9:672039. [PMID: 34079803 PMCID: PMC8166268 DOI: 10.3389/fcell.2021.672039] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Accepted: 04/06/2021] [Indexed: 11/13/2022] Open
Abstract
In the past decades, researchers discovered the contribution of genetic defects to the pathogenesis of primary cardiomyopathy and tried to explain the pathogenesis of these diseases by establishing a variety of disease models. Although human heart tissues and primary cardiomyocytes have advantages in modeling human heart diseases, they are difficult to obtain and culture in vitro. Defects developed in genetically modified animal models are notably different from human diseases at the molecular level. The advent of human induced pluripotent stem cells (hiPSCs) provides an unprecedented opportunity to further investigate the pathogenic mechanisms of inherited cardiomyopathies in vitro using patient-specific hiPSC-derived cardiomyocytes. In this review, we will make a summary of recent advances in in vitro inherited cardiomyopathy modeling using hiPSCs.
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Affiliation(s)
- Xue Jiang
- Department of Cardiovascular Surgery of The First Affiliated Hospital & Institute for Cardiovascular Science, Collaborative Innovation Center of Hematology, State Key Laboratory of Radiation Medicine and Protection, Medical College, Soochow University, Suzhou, China
| | - Yihuan Chen
- Department of Cardiovascular Surgery of The First Affiliated Hospital & Institute for Cardiovascular Science, Collaborative Innovation Center of Hematology, State Key Laboratory of Radiation Medicine and Protection, Medical College, Soochow University, Suzhou, China
| | - Xiaofeng Liu
- The Affiliated Haian Hospital of Nantong University, Nantong, China
| | - Lingqun Ye
- Department of Cardiovascular Surgery of The First Affiliated Hospital & Institute for Cardiovascular Science, Collaborative Innovation Center of Hematology, State Key Laboratory of Radiation Medicine and Protection, Medical College, Soochow University, Suzhou, China
| | - Miao Yu
- Department of Cardiovascular Surgery of The First Affiliated Hospital & Institute for Cardiovascular Science, Collaborative Innovation Center of Hematology, State Key Laboratory of Radiation Medicine and Protection, Medical College, Soochow University, Suzhou, China
| | - Zhenya Shen
- Department of Cardiovascular Surgery of The First Affiliated Hospital & Institute for Cardiovascular Science, Collaborative Innovation Center of Hematology, State Key Laboratory of Radiation Medicine and Protection, Medical College, Soochow University, Suzhou, China
| | - Wei Lei
- Department of Cardiovascular Surgery of The First Affiliated Hospital & Institute for Cardiovascular Science, Collaborative Innovation Center of Hematology, State Key Laboratory of Radiation Medicine and Protection, Medical College, Soochow University, Suzhou, China
| | - Shijun Hu
- Department of Cardiovascular Surgery of The First Affiliated Hospital & Institute for Cardiovascular Science, Collaborative Innovation Center of Hematology, State Key Laboratory of Radiation Medicine and Protection, Medical College, Soochow University, Suzhou, China
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29
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Schänzer A, Schumann E, Zengeler D, Gulatz L, Maroli G, Ahting U, Sprengel A, Gräf S, Hahn A, Jux C, Acker T, Fürst DO, Rupp S, Schuld J, van der Ven PFM. The p.Ala2430Val mutation in filamin C causes a "hypertrophic myofibrillar cardiomyopathy". J Muscle Res Cell Motil 2021; 42:381-397. [PMID: 33710525 DOI: 10.1007/s10974-021-09601-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Accepted: 02/26/2021] [Indexed: 10/21/2022]
Abstract
Hypertrophic cardiomyopathy (HCM) often leads to heart failure. Mutations in sarcomeric proteins are most frequently the cause of HCM but in many patients the gene defect is not known. Here we report on a young man who was diagnosed with HCM shortly after birth. Whole exome sequencing revealed a mutation in the FLNC gene (c.7289C > T; p.Ala2430Val) that was previously shown to cause aggregation of the mutant protein in transfected cells. Myocardial tissue from patients with this mutation has not been analyzed before and thus, the underlying etiology is not well understood. Myocardial tissue of our patient obtained during myectomy at the age of 23 years was analyzed in detail by histochemistry, immunofluorescence staining, electron microscopy and western blot analysis. Cardiac histology showed a pathology typical for myofibrillar myopathy with myofibril disarray and abnormal protein aggregates containing BAG3, desmin, HSPB5 and filamin C. Analysis of sarcomeric and intercalated disc proteins showed focally reduced expression of the gap junction protein connexin43 and Xin-positive sarcomeric lesions in the cardiomyocytes of our patient. In addition, autophagy pathways were altered with upregulation of LC3-II, WIPI1 and HSPB5, 6, 7 and 8. We conclude that the p.Ala2430Val mutation in FLNC most probably is associated with HCM characterized by abnormal intercalated discs, disarray of myofibrils and aggregates containing Z-disc proteins similar to myofibrillar myopathy, which supports the pathological effect of the mutation.
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Affiliation(s)
- Anne Schänzer
- Institute of Neuropathology, Justus Liebig University, Arndstr.16, 35392, Giessen, Germany.
| | - Elisabeth Schumann
- Institute of Neuropathology, Justus Liebig University, Arndstr.16, 35392, Giessen, Germany
| | - Diana Zengeler
- Center for Genomics and Transcriptomics (CeGat) GmbH, Tübingen, Germany
| | - Lisann Gulatz
- Institute of Neuropathology, Justus Liebig University, Arndstr.16, 35392, Giessen, Germany
| | - Giovanni Maroli
- Department of Cardiac Development and Remodeling, Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany
| | - Uwe Ahting
- Institute of Human Genetics, Technical University of Munich (TUM), Munich, Germany
| | - Anke Sprengel
- Pediatric Heart Center, Justus Liebig University, Giessen, Germany
| | - Sabine Gräf
- Institute of Neuropathology, Justus Liebig University, Arndstr.16, 35392, Giessen, Germany
| | - Andreas Hahn
- Department of Child Neurology, Justus Liebig University, Giessen, Germany
| | - Christian Jux
- Pediatric Heart Center, Justus Liebig University, Giessen, Germany
| | - Till Acker
- Institute of Neuropathology, Justus Liebig University, Arndstr.16, 35392, Giessen, Germany
| | - Dieter O Fürst
- Department of Molecular Cell Biology, Institute for Cell Biology, University of Bonn, Bonn, Germany
| | - Stefan Rupp
- Pediatric Heart Center, Justus Liebig University, Giessen, Germany
| | - Julia Schuld
- Department of Molecular Cell Biology, Institute for Cell Biology, University of Bonn, Bonn, Germany
| | - Peter F M van der Ven
- Department of Molecular Cell Biology, Institute for Cell Biology, University of Bonn, Bonn, Germany
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30
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Rees M, Nikoopour R, Fukuzawa A, Kho AL, Fernandez-Garcia MA, Wraige E, Bodi I, Deshpande C, Özdemir Ö, Daimagüler HS, Pfuhl M, Holt M, Brandmeier B, Grover S, Fluss J, Longman C, Farrugia ME, Matthews E, Hanna M, Muntoni F, Sarkozy A, Phadke R, Quinlivan R, Oates EC, Schröder R, Thiel C, Reimann J, Voermans N, Erasmus C, Kamsteeg EJ, Konersman C, Grosmann C, McKee S, Tirupathi S, Moore SA, Wilichowski E, Hobbiebrunken E, Dekomien G, Richard I, Van den Bergh P, Domínguez-González C, Cirak S, Ferreiro A, Jungbluth H, Gautel M. Making sense of missense variants in TTN-related congenital myopathies. Acta Neuropathol 2021; 141:431-453. [PMID: 33449170 PMCID: PMC7882473 DOI: 10.1007/s00401-020-02257-0] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 12/20/2020] [Accepted: 12/20/2020] [Indexed: 12/15/2022]
Abstract
Mutations in the sarcomeric protein titin, encoded by TTN, are emerging as a common cause of myopathies. The diagnosis of a TTN-related myopathy is, however, often not straightforward due to clinico-pathological overlap with other myopathies and the prevalence of TTN variants in control populations. Here, we present a combined clinico-pathological, genetic and biophysical approach to the diagnosis of TTN-related myopathies and the pathogenicity ascertainment of TTN missense variants. We identified 30 patients with a primary TTN-related congenital myopathy (CM) and two truncating variants, or one truncating and one missense TTN variant, or homozygous for one TTN missense variant. We found that TTN-related myopathies show considerable overlap with other myopathies but are strongly suggested by a combination of certain clinico-pathological features. Presentation was typically at birth with the clinical course characterized by variable progression of weakness, contractures, scoliosis and respiratory symptoms but sparing of extraocular muscles. Cardiac involvement depended on the variant position. Our biophysical analyses demonstrated that missense mutations associated with CMs are strongly destabilizing and exert their effect when expressed on a truncating background or in homozygosity. We hypothesise that destabilizing TTN missense mutations phenocopy truncating variants and are a key pathogenic feature of recessive titinopathies that might be amenable to therapeutic intervention.
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Affiliation(s)
- Martin Rees
- Randall Centre for Cell and Molecular Biophysics, Muscle Biophysics, King's College London BHF Centre of Research Excellence, London, UK
| | - Roksana Nikoopour
- Randall Centre for Cell and Molecular Biophysics, Muscle Biophysics, King's College London BHF Centre of Research Excellence, London, UK
| | - Atsushi Fukuzawa
- Randall Centre for Cell and Molecular Biophysics, Muscle Biophysics, King's College London BHF Centre of Research Excellence, London, UK
| | - Ay Lin Kho
- Randall Centre for Cell and Molecular Biophysics, Muscle Biophysics, King's College London BHF Centre of Research Excellence, London, UK
| | - Miguel A Fernandez-Garcia
- Department of Paediatric Neurology, Evelina Children's Hospital, Guy's & St Thomas' NHS Foundation Trust, London, UK
| | - Elizabeth Wraige
- Department of Paediatric Neurology, Evelina Children's Hospital, Guy's & St Thomas' NHS Foundation Trust, London, UK
| | - Istvan Bodi
- Department of Clinical Neuropathology, King's College Hospital, London, UK
| | | | - Özkan Özdemir
- Centre for Molecular Medicine, University of Cologne, Cologne, Germany
- Department of Pediatrics, University Hospital Cologne and Faculty of Medicine, University of Cologne, Cologne, Germany
| | - Hülya-Sevcan Daimagüler
- Centre for Molecular Medicine, University of Cologne, Cologne, Germany
- Department of Pediatrics, University Hospital Cologne and Faculty of Medicine, University of Cologne, Cologne, Germany
| | - Mark Pfuhl
- Randall Centre for Cell and Molecular Biophysics, Muscle Biophysics, King's College London BHF Centre of Research Excellence, London, UK
- School of Cardiovascular Medicine and Sciences, King's College London BHF Centre of Research Excellence, London, UK
| | - Mark Holt
- Randall Centre for Cell and Molecular Biophysics, Muscle Biophysics, King's College London BHF Centre of Research Excellence, London, UK
- School of Cardiovascular Medicine and Sciences, King's College London BHF Centre of Research Excellence, London, UK
| | - Birgit Brandmeier
- Randall Centre for Cell and Molecular Biophysics, Muscle Biophysics, King's College London BHF Centre of Research Excellence, London, UK
| | - Sarah Grover
- Randall Centre for Cell and Molecular Biophysics, Muscle Biophysics, King's College London BHF Centre of Research Excellence, London, UK
| | - Joël Fluss
- Pediatric Neurology Unit, Paediatrics Subspecialties Service, Geneva Children's Hospital, Geneva, Switzerland
| | - Cheryl Longman
- West of Scotland Regional Genetics Service, Laboratory Medicine Building, Queen Elizabeth University Hospital, Glasgow, UK
| | | | - Emma Matthews
- MRC Neuromuscular Centre, National Hospital for Neurology and Neurosurgery, Queen's Square, London, UK
| | - Michael Hanna
- MRC Neuromuscular Centre, National Hospital for Neurology and Neurosurgery, Queen's Square, London, UK
| | - Francesco Muntoni
- Dubowitz Neuromuscular Centre, Great Ormond Street Hospital for Children, London, UK
- NIHR Great Ormond Street Hospital Biomedical Research Centre, Great Ormond Street Institute of Child Health, University College London, Great Ormond Street Hospital Trust, London, UK
| | - Anna Sarkozy
- Dubowitz Neuromuscular Centre, Great Ormond Street Hospital for Children, London, UK
| | - Rahul Phadke
- Dubowitz Neuromuscular Centre, Great Ormond Street Hospital for Children, London, UK
| | - Ros Quinlivan
- Dubowitz Neuromuscular Centre, Great Ormond Street Hospital for Children, London, UK
| | - Emily C Oates
- Dubowitz Neuromuscular Centre, Great Ormond Street Hospital for Children, London, UK
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sidney, Australia
- Kids Neuroscience Centre, Kids Research, The Children's Hospital at Westmead, Sydney, NSW, Australia
| | - Rolf Schröder
- Institute of Neuropathology, University Hospital Erlangen, Friedrich-Alexander Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Christian Thiel
- Department of Genetics, University of Erlangen, Erlangen, Germany
| | - Jens Reimann
- Muscle Laboratory, Department of Neurology, University of Bonn Medical Centre, Bonn, Germany
| | - Nicol Voermans
- Department of Neurology, Donders Institute for Brain, Cognition and Behaviour, Radboud University, Nijmegen, The Netherlands
| | - Corrie Erasmus
- Department of Paediatric Neurology, Radboud University, Nijmegen, The Netherlands
| | - Erik-Jan Kamsteeg
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Chaminda Konersman
- UCSD, Rady Children's Hospital, and VA San Diego Healthcare System, San Diego, USA
| | | | - Shane McKee
- Northern Ireland Regional Genetics Service, Belfast City Hospital, Belfast, UK
| | - Sandya Tirupathi
- Department of Paediatric Neurology, Royal Belfast Hospital for Sick Children, Belfast, UK
| | - Steven A Moore
- Department of Pathology, The University of Iowa, Iowa City, IA, USA
| | | | - Elke Hobbiebrunken
- Department of Paediatric Neurology, University of Göttingen, Göttingen, Germany
| | | | - Isabelle Richard
- Genethon and UMR_S951, INSERM, Université Evry, Université Paris Saclay, Evry, 91002, Evry, France
| | - Peter Van den Bergh
- Neuromuscular Reference Centre, Department of Neurology, University Hospital Saint-Luc, Brussels, Belgium
| | | | - Sebahattin Cirak
- Centre for Molecular Medicine, University of Cologne, Cologne, Germany
- Department of Pediatrics, University Hospital Cologne and Faculty of Medicine, University of Cologne, Cologne, Germany
- Centre for Rare Diseases (ZSEK), University of Cologne, Cologne, Germany
| | - Ana Ferreiro
- Basic and Translational Myology Laboratory, Université de Paris, Paris, France
- Centre de Référence Des Maladies Neuromusculaires, APHP, Institut of Myology, GHU Pitié Salpêtrière- Charles Foix, Paris, France
| | - Heinz Jungbluth
- Randall Centre for Cell and Molecular Biophysics, Muscle Biophysics, King's College London BHF Centre of Research Excellence, London, UK
- Department of Paediatric Neurology, Evelina Children's Hospital, Guy's & St Thomas' NHS Foundation Trust, London, UK
- Department of Clinical and Basic Neuroscience, IoPPN, King's College London, London, UK
| | - Mathias Gautel
- Randall Centre for Cell and Molecular Biophysics, Muscle Biophysics, King's College London BHF Centre of Research Excellence, London, UK.
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31
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Martínez de Morentin Navarcorena AL, Izquierdo Álvarez S, Palanca Arias D. Postnatal cardiomyopathy in a newborn with Salih myopathy. Med Clin (Barc) 2021; 157:499-500. [PMID: 33485616 DOI: 10.1016/j.medcli.2020.11.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Revised: 10/27/2020] [Accepted: 11/02/2020] [Indexed: 10/22/2022]
Affiliation(s)
| | - Silvia Izquierdo Álvarez
- Unidad de Genética, Departamento de Bioquímica Clínica, Hospital Infantil Universitario Miguel Servet, Zaragoza, España
| | - Daniel Palanca Arias
- Unidad de Cuidados Intensivos Pediátricos, Hospital Infantil Universitario Miguel Servet, Zaragoza, España; Unidad de Cardiología Pediátrica, Hospital Infantil Universitario Miguel Servet, Zaragoza, España
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32
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Shchendrigina AA, Zhbanov KA, Privalova EV, Iusupova AO, Bytdaeva AH, Danilogorskaya YA, Zheleznykh EA, Suvorov AY, Zektser VY, Mnatsakanyan MG, Lyapidevskaya OV, Khabarova NV, Naymann YI, Belenkov YN, Starostina ES. [Circulating Neuregulin-1 and Chronic Heart Failure with Preserved Ejection]. ACTA ACUST UNITED AC 2020; 60:1222. [PMID: 33487159 DOI: 10.18087/cardio.2020.11.n1222] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Accepted: 10/08/2020] [Indexed: 11/18/2022]
Abstract
Chronic heart failure (CHF) with preserved ejection fraction (CHFpEF) is an unsolved, socially relevant challenge since it is associated with a high level of morbidity and mortality. Early markers for this pathology are unavailable, and therapeutic approaches are undeveloped. This necessitates extensive studying the mechanisms of CHFpEF to identify therapeutic targets. According to current notions, systemic inflammation and endothelial dysfunction play an important role in the pathogenesis of CHFpEF. These processes induce the development of myocardial fibrosis and impairment of cardiomyocyte relaxation, thereby resulting in diastolic dysfunction and increased left ventricular (LV) filling pressure. Neuregulin-1 (NRG-1) is a paracrine growth factor and a natural agonist of ErbB receptor family synthesized in the endothelium of coronary microvessels. The NRG-1 / ErbB4 system of the heart is activated at early stages of CHFpEF to enhance the cardiomyocyte resistance to oxidative stress. Preclinical and clinical (phases II and III) studies have shown that the recombinant NRG-1 therapy results in improvement of myocardial contractility and in LV reverse remodeling. Results of recent studies suggest possible anti-inflammatory and antifibrotic effects of NRG-1, which warrants studying the activity of this system in patients with CHFpEF.
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Affiliation(s)
- A A Shchendrigina
- I.M. Sechenov First Moscow State Medical University (Sechenov University), Moscow
| | - K A Zhbanov
- I.M. Sechenov First Moscow State Medical University (Sechenov University), Moscow
| | - E V Privalova
- I.M. Sechenov First Moscow State Medical University (Sechenov University), Moscow
| | - A O Iusupova
- I.M. Sechenov First Moscow State Medical University (Sechenov University), Moscow
| | - A H Bytdaeva
- I.M. Sechenov First Moscow State Medical University (Sechenov University), Moscow
| | - Yu A Danilogorskaya
- I.M. Sechenov First Moscow State Medical University (Sechenov University), Moscow
| | - E A Zheleznykh
- I.M. Sechenov First Moscow State Medical University (Sechenov University), Moscow
| | | | - V Yu Zektser
- I.M. Sechenov First Moscow State Medical University (Sechenov University), Moscow
| | - M G Mnatsakanyan
- I.M. Sechenov First Moscow State Medical University (Sechenov University), Moscow
| | - O V Lyapidevskaya
- I.M. Sechenov First Moscow State Medical University (Sechenov University), Moscow
| | - N V Khabarova
- I.M. Sechenov First Moscow State Medical University (Sechenov University), Moscow
| | - Yu I Naymann
- I.M. Sechenov First Moscow State Medical University (Sechenov University), Moscow
| | - Yu N Belenkov
- I.M. Sechenov First Moscow State Medical University (Sechenov University), Moscow
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33
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Kono F, Kawai S, Shimamoto Y, Ishiwata S. Nanoscopic changes in the lattice structure of striated muscle sarcomeres involved in the mechanism of spontaneous oscillatory contraction (SPOC). Sci Rep 2020; 10:16372. [PMID: 33009449 PMCID: PMC7532212 DOI: 10.1038/s41598-020-73247-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Accepted: 09/11/2020] [Indexed: 02/06/2023] Open
Abstract
Muscles perform a wide range of motile functions in animals. Among various types are skeletal and cardiac muscles, which exhibit a steady auto-oscillation of force and length when they are activated at an intermediate level of contraction. This phenomenon, termed spontaneous oscillatory contraction or SPOC, occurs devoid of cell membranes and at fixed concentrations of chemical substances, and is thus the property of the contractile system per se. We have previously developed a theoretical model of SPOC and proposed that the oscillation emerges from a dynamic force balance along both the longitudinal and lateral axes of sarcomeres, the contractile units of the striated muscle. Here, we experimentally tested this hypothesis by developing an imaging-based analysis that facilitates detection of the structural changes of single sarcomeres at unprecedented spatial resolution. We found that the sarcomere width oscillates anti-phase with the sarcomere length in SPOC. We also found that the oscillatory dynamics can be altered by osmotic compression of the myofilament lattice structure of sarcomeres, but they are unchanged by a proteolytic digestion of titin/connectin—the spring-like protein that provides passive elasticity to sarcomeres. Our data thus reveal the three-dimensional mechanical dynamics of oscillating sarcomeres and suggest a structural requirement of steady auto-oscillation.
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Affiliation(s)
- Fumiaki Kono
- Department of Physics, Faculty of Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku-ku, Tokyo, 169-8555, Japan.,Institute for Quantum Life Science, National Institutes for Quantum and Radiological Science and Technology, 2-4 Shirakata, Tokai-mura, Naka-gun, Ibaraki, 319-1106, Japan
| | - Seitaro Kawai
- Department of Physics, Faculty of Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku-ku, Tokyo, 169-8555, Japan
| | - Yuta Shimamoto
- Laboratory of Physics and Cell Biology, Department of Chromosome Science, National Institute of Genetics, 1111 Yata, Mishima, Shizuoka, 411-8540, Japan.
| | - Shin'ichi Ishiwata
- Department of Physics, Faculty of Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku-ku, Tokyo, 169-8555, Japan.
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Swist S, Unger A, Li Y, Vöge A, von Frieling-Salewsky M, Skärlén Å, Cacciani N, Braun T, Larsson L, Linke WA. Maintenance of sarcomeric integrity in adult muscle cells crucially depends on Z-disc anchored titin. Nat Commun 2020; 11:4479. [PMID: 32900999 PMCID: PMC7478974 DOI: 10.1038/s41467-020-18131-2] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2019] [Accepted: 08/04/2020] [Indexed: 12/14/2022] Open
Abstract
The giant protein titin is thought to be required for sarcomeric integrity in mature myocytes, but direct evidence for this hypothesis is limited. Here, we describe a mouse model in which Z-disc-anchored TTN is depleted in adult skeletal muscles. Inactivation of TTN causes sarcomere disassembly and Z-disc deformations, force impairment, myocyte de-stiffening, upregulation of TTN-binding mechanosensitive proteins and activation of protein quality-control pathways, concomitant with preferential loss of thick-filament proteins. Interestingly, expression of the myosin-bound Cronos-isoform of TTN, generated from an alternative promoter not affected by the targeting strategy, does not prevent deterioration of sarcomere formation and maintenance. Finally, we demonstrate that loss of Z-disc-anchored TTN recapitulates muscle remodeling in critical illness ‘myosinopathy’ patients, characterized by TTN-depletion and loss of thick filaments. We conclude that full-length TTN is required to integrate Z-disc and A-band proteins into the mature sarcomere, a function that is lost when TTN expression is pathologically lowered. Titin is considered an integrator of muscle cell proteins but direct evidence is limited. Here, titin is inactivated in adult mouse muscles, which causes sarcomere disassembly, protein mis-expression and force impairment, recapitulating key alterations in critical illness myopathy patient muscles.
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Affiliation(s)
- Sandra Swist
- Department of Systems Physiology, Ruhr University Bochum, D-44780, Bochum, Germany.
| | - Andreas Unger
- Institute of Physiology II, University of Munster, D-48149, Munster, Germany
| | - Yong Li
- Institute of Physiology II, University of Munster, D-48149, Munster, Germany
| | - Anja Vöge
- Department of Systems Physiology, Ruhr University Bochum, D-44780, Bochum, Germany
| | | | - Åsa Skärlén
- Department of Clinical Neuroscience, Clinical Neurophysiology, Karolinska Institute, SE-171 77, Stockholm, Sweden
| | - Nicola Cacciani
- Department of Physiology and Pharmacology, Karolinska Institute, SE-171 77, Stockholm, Sweden
| | - Thomas Braun
- Department of Cardiac Development and Remodeling, Max Planck Institute for Heart and Lung Research, D-61231, Bad Nauheim, Germany
| | - Lars Larsson
- Department of Physiology and Pharmacology, Karolinska Institute, SE-171 77, Stockholm, Sweden
| | - Wolfgang A Linke
- Institute of Physiology II, University of Munster, D-48149, Munster, Germany.
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Schuld J, Orfanos Z, Chevessier F, Eggers B, Heil L, Uszkoreit J, Unger A, Kirfel G, van der Ven PFM, Marcus K, Linke WA, Clemen CS, Schröder R, Fürst DO. Homozygous expression of the myofibrillar myopathy-associated p.W2710X filamin C variant reveals major pathomechanisms of sarcomeric lesion formation. Acta Neuropathol Commun 2020; 8:154. [PMID: 32887649 PMCID: PMC7650280 DOI: 10.1186/s40478-020-01001-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Accepted: 07/22/2020] [Indexed: 01/06/2023] Open
Abstract
Filamin C (FLNc) is mainly expressed in striated muscle cells where it localizes to Z-discs, myotendinous junctions and intercalated discs. Recent studies have revealed numerous mutations in the FLNC gene causing familial and sporadic myopathies and cardiomyopathies with marked clinical variability. The most frequent myopathic mutation, p.W2710X, which is associated with myofibrillar myopathy, deletes the carboxy-terminal 16 amino acids from FLNc and abolishes the dimerization property of Ig-like domain 24. We previously characterized "knock-in" mice heterozygous for this mutation (p.W2711X), and have now investigated homozygous mice using protein and mRNA expression analyses, mass spectrometry, and extensive immunolocalization and ultrastructural studies. Although the latter mice display a relatively mild myopathy under normal conditions, our analyses identified major mechanisms causing the pathophysiology of this disease: in comparison to wildtype animals (i) the expression level of FLNc protein is drastically reduced; (ii) mutant FLNc is relocalized from Z-discs to particularly mechanically strained parts of muscle cells, i.e. myotendinous junctions and myofibrillar lesions; (iii) the number of lesions is greatly increased and these lesions lack Bcl2-associated athanogene 3 (BAG3) protein; (iv) the expression of heat shock protein beta-7 (HSPB7) is almost completely abolished. These findings indicate grave disturbances of BAG3-dependent and -independent autophagy pathways that are required for efficient lesion repair. In addition, our studies reveal general mechanisms of lesion formation and demonstrate that defective FLNc dimerization via its carboxy-terminal domain does not disturb assembly and basic function of myofibrils. An alternative, more amino-terminally located dimerization site might compensate for that loss. Since filamins function as stress sensors, our data further substantiate that FLNc is important for mechanosensing in the context of Z-disc stabilization and maintenance.
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Modifications of Titin Contribute to the Progression of Cardiomyopathy and Represent a Therapeutic Target for Treatment of Heart Failure. J Clin Med 2020; 9:jcm9092770. [PMID: 32859027 PMCID: PMC7564493 DOI: 10.3390/jcm9092770] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 08/22/2020] [Accepted: 08/24/2020] [Indexed: 12/20/2022] Open
Abstract
Titin is the largest human protein and an essential component of the cardiac sarcomere. With multiple immunoglobulin(Ig)-like domains that serve as molecular springs, titin contributes significantly to the passive tension, systolic function, and diastolic function of the heart. Mutations leading to early termination of titin are the most common genetic cause of dilated cardiomyopathy. Modifications of titin, which change protein length, and relative stiffness affect resting tension of the ventricle and are associated with acquired forms of heart failure. Transcriptional and post-translational changes that increase titin’s length and extensibility, making the sarcomere longer and softer, are associated with systolic dysfunction and left ventricular dilation. Modifications of titin that decrease its length and extensibility, making the sarcomere shorter and stiffer, are associated with diastolic dysfunction in animal models. There has been significant progress in understanding the mechanisms by which titin is modified. As molecular pathways that modify titin’s mechanical properties are elucidated, they represent therapeutic targets for treatment of both systolic and diastolic dysfunction. In this article, we review titin’s contribution to normal cardiac physiology, the pathophysiology of titin truncation variations leading to dilated cardiomyopathy, and transcriptional and post-translational modifications of titin. Emphasis is on how modification of titin can be utilized as a therapeutic target for treatment of heart failure.
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Chen MP, Kiduko SA, Saad NS, Canan BD, Kilic A, Mohler PJ, Janssen PML. Stretching single titin molecules from failing human hearts reveals titin's role in blunting cardiac kinetic reserve. Cardiovasc Res 2020; 116:127-137. [PMID: 30778519 DOI: 10.1093/cvr/cvz043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Revised: 11/08/2018] [Accepted: 02/13/2019] [Indexed: 11/15/2022] Open
Abstract
AIMS Heart failure (HF) patients commonly experience symptoms primarily during elevated heart rates, as a result of physical activities or stress. A main determinant of diastolic passive tension, the elastic sarcomeric protein titin, has been shown to be associated with HF, with unresolved involvement regarding its role at different heart rates. To determine whether titin is playing a role in the heart rate (frequency-) dependent acceleration of relaxation (FDAR). W, we studied the FDAR responses in live human left ventricular cardiomyocytes and the corresponding titin-based passive tension (TPT) from failing and non-failing human hearts. METHODS AND RESULTS Using atomic force, we developed a novel single-molecule force spectroscopy approach to detect TPT based on the frequency-modulated cardiac cycle. Mean TPT reduced upon an increased heart rate in non-failing human hearts, while this reduction was significantly blunted in failing human hearts. These mechanical changes in the titin distal Ig domain significantly correlated with the frequency-dependent relaxation kinetics of human cardiomyocytes obtained from the corresponding hearts. Furthermore, the data suggested that the higher the TPT, the faster the cardiomyocytes relaxed, but the lower the potential of myocytes to speed up relaxation at a higher heart rate. Such poorer FDAR response was also associated with a lesser reduction or a bigger increase in TPT upon elevated heart rate. CONCLUSIONS Our study established a novel approach in detecting dynamic heart rate relevant tension changes physiologically on native titin domains. Using this approach, the data suggested that the regulation of kinetic reserve in cardiac relaxation and its pathological changes were associated with the intensity and dynamic changes of passive tension by titin.
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Affiliation(s)
- Mei-Pian Chen
- Department of Physiology and Cell Biology, The Ohio State University, Hamilton Hall 207a, 1645 Neil Avenue, Columbus, OH 43210, USA.,Dorothy M. Davis Heart and Lung Research Institute, 473 W 12th Ave, Columbus, OH 43210 USA
| | - Salome A Kiduko
- Department of Physiology and Cell Biology, The Ohio State University, Hamilton Hall 207a, 1645 Neil Avenue, Columbus, OH 43210, USA.,Dorothy M. Davis Heart and Lung Research Institute, 473 W 12th Ave, Columbus, OH 43210 USA
| | - Nancy S Saad
- Department of Physiology and Cell Biology, The Ohio State University, Hamilton Hall 207a, 1645 Neil Avenue, Columbus, OH 43210, USA.,Dorothy M. Davis Heart and Lung Research Institute, 473 W 12th Ave, Columbus, OH 43210 USA.,Department of Pharmacology and Toxicology, Faculty of Pharmacy, Helwan University, Cairo, Egypt
| | - Benjamin D Canan
- Department of Physiology and Cell Biology, The Ohio State University, Hamilton Hall 207a, 1645 Neil Avenue, Columbus, OH 43210, USA.,Dorothy M. Davis Heart and Lung Research Institute, 473 W 12th Ave, Columbus, OH 43210 USA
| | - Ahmet Kilic
- Division of Cardiothoracic Surgery, Department of Surgery, The Ohio State University Wexner Medical Center, 410 W 10th Ave, Columbus, OH 43210, USA
| | - Peter J Mohler
- Department of Physiology and Cell Biology, The Ohio State University, Hamilton Hall 207a, 1645 Neil Avenue, Columbus, OH 43210, USA.,Dorothy M. Davis Heart and Lung Research Institute, 473 W 12th Ave, Columbus, OH 43210 USA.,Department of Internal Medicine, The Ohio State University Wexner Medical Center, 395 W 12th Ave, Columbus, OH 43210, USA
| | - Paul M L Janssen
- Department of Physiology and Cell Biology, The Ohio State University, Hamilton Hall 207a, 1645 Neil Avenue, Columbus, OH 43210, USA.,Dorothy M. Davis Heart and Lung Research Institute, 473 W 12th Ave, Columbus, OH 43210 USA.,Department of Internal Medicine, The Ohio State University Wexner Medical Center, 395 W 12th Ave, Columbus, OH 43210, USA
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Bennett P, Rees M, Gautel M. The Axial Alignment of Titin on the Muscle Thick Filament Supports Its Role as a Molecular Ruler. J Mol Biol 2020; 432:4815-4829. [PMID: 32619437 PMCID: PMC7427331 DOI: 10.1016/j.jmb.2020.06.025] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Revised: 06/24/2020] [Accepted: 06/25/2020] [Indexed: 01/04/2023]
Abstract
The giant protein titin is expressed in vertebrate striated muscle where it spans half a sarcomere from the Z-disc to the M-band and is essential for muscle organisation, activity and health. The C-terminal portion of titin is closely associated with the thick, myosin-containing filament and exhibits a complex pattern of immunoglobulin and fibronectin domains. This pattern reflects features of the filament organisation suggesting that it acts as a molecular ruler and template, but the exact axial disposition of the molecule has not been determined. Here, we present data that allow us to precisely locate titin domains axially along the thick filament from its tip to the edge of the bare zone. We find that the domains are regularly distributed along the filament at 4-nm intervals and we can determine the domains that associate with features of the filament, such as the 11 stripes of accessory proteins. We confirm that the nine stripes ascribed to myosin binding protein-C are not related to the titin sequence previously assumed; rather, they relate to positions approximately 18 domains further towards the C terminus along titin. This disposition also allows a subgroup of titin domains comprising two or three fibronectin domains to associate with each of the 49 levels of myosin heads in each half filament. The results strongly support the role of titin as a blueprint for the thick filament and the arrangement of the myosin motor domains.
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Affiliation(s)
- Pauline Bennett
- The Randall Centre for Cell & Molecular Biophysics, School of Basic and Medical Biosciences, New Hunt's House, Guy's Campus, King's College London, London, UK.
| | - Martin Rees
- The Randall Centre for Cell & Molecular Biophysics, School of Basic and Medical Biosciences, New Hunt's House, Guy's Campus, King's College London, London, UK.
| | - Mathias Gautel
- The Randall Centre for Cell & Molecular Biophysics, School of Basic and Medical Biosciences, New Hunt's House, Guy's Campus, King's College London, London, UK.
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39
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The intercalated disc: a mechanosensing signalling node in cardiomyopathy. Biophys Rev 2020; 12:931-946. [PMID: 32661904 PMCID: PMC7429531 DOI: 10.1007/s12551-020-00737-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Accepted: 07/08/2020] [Indexed: 02/08/2023] Open
Abstract
Cardiomyocytes, the cells generating contractile force in the heart, are connected to each other through a highly specialised structure, the intercalated disc (ID), which ensures force transmission and transduction between neighbouring cells and allows the myocardium to function in synchrony. In addition, cardiomyocytes possess an intrinsic ability to sense mechanical changes and to regulate their own contractile output accordingly. To achieve this, some of the components responsible for force transmission have evolved to sense changes in tension and to trigger a biochemical response that results in molecular and cellular changes in cardiomyocytes. This becomes of particular importance in cardiomyopathies, where the heart is exposed to increased mechanical load and needs to adapt to sustain its contractile function. In this review, we will discuss key mechanosensing elements present at the intercalated disc and provide an overview of the signalling molecules involved in mediating the responses to changes in mechanical force.
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40
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Abstract
Muscle has conventionally been viewed as a motor that converts chemical to kinetic energy in series with a passive spring, but new insights emerge when muscle is viewed as a composite material whose elastic elements are tuned by activation. New evidence demonstrates that calcium-dependent binding of N2A titin to actin increases titin stiffness in active skeletal muscles, which explains many long-standing enigmas of muscle physiology.
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Affiliation(s)
- Kiisa Nishikawa
- Department of Biological Sciences, Northern Arizona University, Flagstaff, Arizona
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41
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Rivas-Pardo JA, Li Y, Mártonfalvi Z, Tapia-Rojo R, Unger A, Fernández-Trasancos Á, Herrero-Galán E, Velázquez-Carreras D, Fernández JM, Linke WA, Alegre-Cebollada J. A HaloTag-TEV genetic cassette for mechanical phenotyping of proteins from tissues. Nat Commun 2020; 11:2060. [PMID: 32345978 PMCID: PMC7189229 DOI: 10.1038/s41467-020-15465-9] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2019] [Accepted: 03/09/2020] [Indexed: 11/09/2022] Open
Abstract
Single-molecule methods using recombinant proteins have generated transformative hypotheses on how mechanical forces are generated and sensed in biological tissues. However, testing these mechanical hypotheses on proteins in their natural environment remains inaccesible to conventional tools. To address this limitation, here we demonstrate a mouse model carrying a HaloTag-TEV insertion in the protein titin, the main determinant of myocyte stiffness. Using our system, we specifically sever titin by digestion with TEV protease, and find that the response of muscle fibers to length changes requires mechanical transduction through titin's intact polypeptide chain. In addition, HaloTag-based covalent tethering enables examination of titin dynamics under force using magnetic tweezers. At pulling forces < 10 pN, titin domains are recruited to the unfolded state, and produce 41.5 zJ mechanical work during refolding. Insertion of the HaloTag-TEV cassette in mechanical proteins opens opportunities to explore the molecular basis of cellular force generation, mechanosensing and mechanotransduction.
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Affiliation(s)
- Jaime Andrés Rivas-Pardo
- Department of Biological Sciences, Columbia University, New York, NY, 10027, USA
- Center for Genomics and Bioinformatics, Facultad de Ciencias, Universidad Mayor, Santiago, Chile
| | - Yong Li
- Institute of Physiology II, University of Muenster, Muenster, Germany
| | - Zsolt Mártonfalvi
- Department of Biophysics and Radiation Biology, Semmelweis University, Budapest, Hungary
| | - Rafael Tapia-Rojo
- Department of Biological Sciences, Columbia University, New York, NY, 10027, USA
| | - Andreas Unger
- Institute of Physiology II, University of Muenster, Muenster, Germany
| | | | | | | | - Julio M Fernández
- Department of Biological Sciences, Columbia University, New York, NY, 10027, USA
| | - Wolfgang A Linke
- Institute of Physiology II, University of Muenster, Muenster, Germany.
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Zaunbrecher RJ, Abel AN, Beussman K, Leonard A, von Frieling-Salewsky M, Fields PA, Pabon L, Reinecke H, Yang X, Macadangdang J, Kim DH, Linke WA, Sniadecki NJ, Regnier M, Murry CE. Cronos Titin Is Expressed in Human Cardiomyocytes and Necessary for Normal Sarcomere Function. Circulation 2019; 140:1647-1660. [PMID: 31587567 PMCID: PMC6911360 DOI: 10.1161/circulationaha.119.039521] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
BACKGROUND The giant sarcomere protein titin is important in both heart health and disease. Mutations in the gene encoding for titin (TTN) are the leading known cause of familial dilated cardiomyopathy. The uneven distribution of these mutations within TTN motivated us to seek a more complete understanding of this gene and the isoforms it encodes in cardiomyocyte (CM) sarcomere formation and function. METHODS To investigate the function of titin in human CMs, we used CRISPR/Cas9 to generate homozygous truncations in the Z disk (TTN-Z-/-) and A-band (TTN-A-/-) regions of the TTN gene in human induced pluripotent stem cells. The resulting CMs were characterized with immunostaining, engineered heart tissue mechanical measurements, and single-cell force and calcium measurements. RESULTS After differentiation, we were surprised to find that despite the more upstream mutation, TTN-Z-/--CMs had sarcomeres and visibly contracted, whereas TTN-A-/--CMs did not. We hypothesized that sarcomere formation was caused by the expression of a recently discovered isoform of titin, Cronos, which initiates downstream of the truncation in TTN-Z-/--CMs. Using a custom Cronos antibody, we demonstrate that this isoform is expressed and integrated into myofibrils in human CMs. TTN-Z-/--CMs exclusively express Cronos titin, but these cells produce lower contractile force and have perturbed myofibril bundling compared with controls expressing both full-length and Cronos titin. Cronos titin is highly expressed in human fetal cardiac tissue, and when knocked out in human induced pluripotent stem cell derived CMs, these cells exhibit reduced contractile force and myofibrillar disarray despite the presence of full-length titin. CONCLUSIONS We demonstrate that Cronos titin is expressed in developing human CMs and is able to support partial sarcomere formation in the absence of full-length titin. Furthermore, Cronos titin is necessary for proper sarcomere function in human induced pluripotent stem cell derived CMs. Additional investigation is necessary to understand the molecular mechanisms of this novel isoform and how it contributes to human cardiac disease.
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Affiliation(s)
- Rebecca J. Zaunbrecher
- Department of Bioengineering, University of Washington, Seattle, WA
- Center for Cardiovascular Biology, University of Washington, Seattle, WA
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA
| | - Ashley N. Abel
- Center for Cardiovascular Biology, University of Washington, Seattle, WA
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA
| | - Kevin Beussman
- Department of Mechanical Engineering, University of Washington, Seattle, WA
- Center for Cardiovascular Biology, University of Washington, Seattle, WA
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA
| | - Andrea Leonard
- Department of Mechanical Engineering, University of Washington, Seattle, WA
- Center for Cardiovascular Biology, University of Washington, Seattle, WA
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA
| | | | - Paul A. Fields
- Department of Pathology, University of Washington, Seattle, WA
- Center for Cardiovascular Biology, University of Washington, Seattle, WA
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA
| | - Lil Pabon
- Department of Pathology, University of Washington, Seattle, WA
- Center for Cardiovascular Biology, University of Washington, Seattle, WA
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA
| | - Hans Reinecke
- Department of Pathology, University of Washington, Seattle, WA
- Center for Cardiovascular Biology, University of Washington, Seattle, WA
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA
| | - Xiulan Yang
- Department of Pathology, University of Washington, Seattle, WA
- Center for Cardiovascular Biology, University of Washington, Seattle, WA
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA
| | - Jesse Macadangdang
- Department of Bioengineering, University of Washington, Seattle, WA
- Center for Cardiovascular Biology, University of Washington, Seattle, WA
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA
| | - Deok-Ho Kim
- Department of Bioengineering, University of Washington, Seattle, WA
- Center for Cardiovascular Biology, University of Washington, Seattle, WA
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA
| | - Wolfgang A. Linke
- Institute of Physiology II, University of Muenster, Robert-Koch-Str. 27b, D-48149 Muenster, Germany
- Deutsches Zentrum für Herz-Kreislaufforschung, Partner Site Goettingen, Germany
| | - Nathan J. Sniadecki
- Department of Mechanical Engineering, University of Washington, Seattle, WA
- Center for Cardiovascular Biology, University of Washington, Seattle, WA
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA
| | - Michael Regnier
- Department of Bioengineering, University of Washington, Seattle, WA
- Center for Cardiovascular Biology, University of Washington, Seattle, WA
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA
| | - Charles E. Murry
- Department of Bioengineering, University of Washington, Seattle, WA
- Department of Pathology, University of Washington, Seattle, WA
- Center for Cardiovascular Biology, University of Washington, Seattle, WA
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA
- Department of Medicine/Cardiology, University of Washington, Seattle, WA
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Ulanova AD, Gritsyna YV, Zhalimov VK, Bobyleva LG, Belova SP, Nemirovskaya TL, Shenkman BS, Vikhlyantsev IM. A 3-Day Functional Unloading is Accompanied by an Increase in the TTN Gene Expression in the Rat Soleus Muscle without Changes in Alternative Splicing from Exon 50 to Exon 111. Biophysics (Nagoya-shi) 2019. [DOI: 10.1134/s0006350919050245] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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44
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Salcan S, Bongardt S, Monteiro Barbosa D, Efimov IR, Rassaf T, Krüger M, Kötter S. Elastic titin properties and protein quality control in the aging heart. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2019; 1867:118532. [PMID: 31421188 DOI: 10.1016/j.bbamcr.2019.118532] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Revised: 07/12/2019] [Accepted: 08/12/2019] [Indexed: 01/09/2023]
Abstract
Cardiac aging affects the heart on the functional, structural, and molecular level and shares characteristic hallmarks with the development of chronic heart failure. Apart from age-dependent left ventricular hypertrophy and fibrosis that impairs diastolic function, diminished activity of cardiac protein-quality-control systems increases the risk of cytotoxic accumulation of defective proteins. Here, we studied the impact of cardiac aging on the sarcomeric protein titin by analyzing titin-based cardiomyocyte passive tension, titin modification and proteasomal titin turnover. We analyzed left ventricular samples from young (6 months) and old (20 months) wild-type mice and healthy human donor patients grouped according to age in young (17-50 years) and aged hearts (51-73 years). We found no age-dependent differences in titin isoform composition of mouse or human hearts. In aged hearts from mice and human we determined altered titin phosphorylation at serine residues S4010 and S4099 in the elastic N2B domain, but no significant changes in phosphorylation of S11878 and S12022 in the elastic PEVK region. Importantly, overall titin-based cardiomyocyte passive tension remained unchanged. In aged hearts, the calcium-activated protease calpain-1, which provides accessibility to ubiquitination by releasing titin from the sarcomere, showed decreased proteolytic activity. In addition, we observed a reduction in the proteasomal activities. Taken together, our data indicate that cardiac aging does not affect titin-based passive properties of the cardiomyocytes, but impairs protein-quality control, including titin, which may result in a diminished adaptive capacity of the aged myocardium.
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Affiliation(s)
- Senem Salcan
- Department of Cardiovascular Physiology, Medical Faculty, Heinrich Heine-University Düsseldorf, D-40225 Düsseldorf, Germany
| | - Sabine Bongardt
- Department of Cardiovascular Physiology, Medical Faculty, Heinrich Heine-University Düsseldorf, D-40225 Düsseldorf, Germany
| | - David Monteiro Barbosa
- Department of Cardiovascular Physiology, Medical Faculty, Heinrich Heine-University Düsseldorf, D-40225 Düsseldorf, Germany
| | - Igor R Efimov
- George Washington University, Department of Biomedical Engineering, Science and Engineering Hall, Washington DC-20052, USA
| | - Tienush Rassaf
- University Hospital Essen, Department of Cardiology and Vascular Medicine, West German Heart and Vascular Center, 45147 Essen, Germany
| | - Martina Krüger
- Department of Cardiovascular Physiology, Medical Faculty, Heinrich Heine-University Düsseldorf, D-40225 Düsseldorf, Germany.
| | - Sebastian Kötter
- Department of Cardiovascular Physiology, Medical Faculty, Heinrich Heine-University Düsseldorf, D-40225 Düsseldorf, Germany.
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45
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Nishikawa K, Dutta S, DuVall M, Nelson B, Gage MJ, Monroy JA. Calcium-dependent titin-thin filament interactions in muscle: observations and theory. J Muscle Res Cell Motil 2019; 41:125-139. [PMID: 31289970 DOI: 10.1007/s10974-019-09540-y] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Accepted: 07/04/2019] [Indexed: 10/26/2022]
Abstract
Gaps in our understanding of muscle mechanics demonstrate that the current model is incomplete. Increasingly, it appears that a role for titin in active muscle contraction might help to fill these gaps. While such a role for titin is increasingly accepted, the underlying molecular mechanisms remain unclear. The goals of this paper are to review recent studies demonstrating Ca2+-dependent interactions between N2A titin and actin in vitro, to explore theoretical predictions of muscle behavior based on this interaction, and to review experimental data related to the predictions. In a recent study, we demonstrated that Ca2+ increases the association constant between N2A titin and F-actin; that Ca2+ increases rupture forces between N2A titin and F-actin; and that Ca2+ and N2A titin reduce sliding velocity of F-actin and reconstituted thin filaments in motility assays. Preliminary data support a role for Ig83, but other Ig domains in the N2A region may also be involved. Two mechanical consequences are inescapable if N2A titin binds to thin filaments in active muscle sarcomeres: (1) the length of titin's freely extensible I-band should decrease upon muscle activation; and (2) binding between N2A titin and thin filaments should increase titin stiffness in active muscle. Experimental observations demonstrate that these properties characterize wild type muscles, but not muscles from mdm mice with a small deletion in N2A titin, including part of Ig83. Given the new in vitro evidence for Ca2+-dependent binding between N2A titin and actin, it is time for skepticism to give way to further investigation.
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Affiliation(s)
- Kiisa Nishikawa
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, 86011-4185, USA.
| | - Samrat Dutta
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, 86011-4185, USA
| | - Michael DuVall
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, 86011-4185, USA.,Edgewise Therapeutics Inc, 3415 Colorado Ave, Boulder, CO, 80303, USA
| | - Brent Nelson
- Department of Mechanical Engineering, Northern Arizona University, Flagstaff, AZ, 86011-15600, USA
| | - Matthew J Gage
- Chemistry Department, University of Massachusetts at Lowell, Lowell, MA, 01854, USA
| | - Jenna A Monroy
- W. M. Keck Science Center, Claremont Colleges, Claremont, CA, 91711-5916, USA
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46
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Koser F, Loescher C, Linke WA. Posttranslational modifications of titin from cardiac muscle: how, where, and what for? FEBS J 2019; 286:2240-2260. [PMID: 30989819 PMCID: PMC6850032 DOI: 10.1111/febs.14854] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Revised: 02/27/2019] [Accepted: 04/13/2019] [Indexed: 12/11/2022]
Abstract
Titin is a giant elastic protein expressed in the contractile units of striated muscle cells, including the sarcomeres of cardiomyocytes. The last decade has seen enormous progress in our understanding of how titin molecular elasticity is modulated in a dynamic manner to help cardiac sarcomeres adjust to the varying hemodynamic demands on the heart. Crucial events mediating the rapid modulation of cardiac titin stiffness are post‐translational modifications (PTMs) of titin. In this review, we first recollect what is known from earlier and recent work on the molecular mechanisms of titin extensibility and force generation. The main goal then is to provide a comprehensive overview of current insight into the relationship between titin PTMs and cardiomyocyte stiffness, notably the effect of oxidation and phosphorylation of titin spring segments on titin stiffness. A synopsis is given of which type of oxidative titin modification can cause which effect on titin stiffness. A large part of the review then covers the mechanically relevant phosphorylation sites in titin, their location along the elastic segment, and the protein kinases and phosphatases known to target these sites. We also include a detailed coverage of the complex changes in phosphorylation at specific titin residues, which have been reported in both animal models of heart disease and in human heart failure, and their correlation with titin‐based stiffness alterations. Knowledge of the relationship between titin PTMs and titin elasticity can be exploited in the search for therapeutic approaches aimed at softening the pathologically stiffened myocardium in heart failure patients.
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47
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Kellermayer D, Smith JE, Granzier H. Titin mutations and muscle disease. Pflugers Arch 2019; 471:673-682. [PMID: 30919088 DOI: 10.1007/s00424-019-02272-5] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Accepted: 03/11/2019] [Indexed: 12/12/2022]
Abstract
The introduction of next-generation sequencing technology has revealed that mutations in the gene that encodes titin (TTN) are linked to multiple skeletal and cardiac myopathies. The most prominent of these myopathies is dilated cardiomyopathy (DCM). Over 60 genes are linked to the etiology of DCM, but by far, the leading cause of DCM is mutations in TTN with truncating variants in TTN (TTNtvs) associated with familial DCM in ∼ 20% of the cases. Titin is a large (3-4 MDa) and abundant protein that forms the third myofilament type of striated muscle where it spans half the sarcomere, from the Z-disk to the M-line. The underlying mechanisms by which titin mutations induce disease are poorly understood and targeted therapies are not available. Here, we review what is known about TTN mutations in muscle disease, with a major focus on DCM. We highlight that exon skipping might provide a possible therapeutic avenue to address diseases that arise from TTNtvs.
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Affiliation(s)
- Dalma Kellermayer
- Department of Cellular and Molecular Medicine, University of Arizona, MRB 325. 1656 E Mabel Street, Tucson, AZ, 85724-5217, USA.,Sarver Molecular Cardiovascular Research Program, University of Arizona, Tucson, AZ, 85721, USA
| | - John E Smith
- Department of Cellular and Molecular Medicine, University of Arizona, MRB 325. 1656 E Mabel Street, Tucson, AZ, 85724-5217, USA.,Sarver Molecular Cardiovascular Research Program, University of Arizona, Tucson, AZ, 85721, USA
| | - Henk Granzier
- Department of Cellular and Molecular Medicine, University of Arizona, MRB 325. 1656 E Mabel Street, Tucson, AZ, 85724-5217, USA. .,Sarver Molecular Cardiovascular Research Program, University of Arizona, Tucson, AZ, 85721, USA.
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48
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Pertici I, Caremani M, Reconditi M. A mechanical model of the half-sarcomere which includes the contribution of titin. J Muscle Res Cell Motil 2019; 40:29-41. [DOI: 10.1007/s10974-019-09508-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2018] [Accepted: 03/08/2019] [Indexed: 11/25/2022]
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49
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Dasbiswas K, Hu S, Schnorrer F, Safran SA, Bershadsky AD. Ordering of myosin II filaments driven by mechanical forces: experiments and theory. Philos Trans R Soc Lond B Biol Sci 2019; 373:rstb.2017.0114. [PMID: 29632266 DOI: 10.1098/rstb.2017.0114] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/30/2017] [Indexed: 12/27/2022] Open
Abstract
Myosin II filaments form ordered superstructures in both cross-striated muscle and non-muscle cells. In cross-striated muscle, myosin II (thick) filaments, actin (thin) filaments and elastic titin filaments comprise the stereotypical contractile units of muscles called sarcomeres. Linear chains of sarcomeres, called myofibrils, are aligned laterally in registry to form cross-striated muscle cells. The experimentally observed dependence of the registered organization of myofibrils on extracellular matrix elasticity has been proposed to arise from the interactions of sarcomeric contractile elements (considered as force dipoles) through the matrix. Non-muscle cells form small bipolar filaments built of less than 30 myosin II molecules. These filaments are associated in registry forming superstructures ('stacks') orthogonal to actin filament bundles. Formation of myosin II filament stacks requires the myosin II ATPase activity and function of the actin filament crosslinking, polymerizing and depolymerizing proteins. We propose that the myosin II filaments embedded into elastic, intervening actin network (IVN) function as force dipoles that interact attractively through the IVN. This is in analogy with the theoretical picture developed for myofibrils where the elastic medium is now the actin cytoskeleton itself. Myosin stack formation in non-muscle cells provides a novel mechanism for the self-organization of the actin cytoskeleton at the level of the entire cell.This article is part of the theme issue 'Self-organization in cell biology'.
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Affiliation(s)
- Kinjal Dasbiswas
- James Franck Institute, University of Chicago, Chicago, IL 60637, USA
| | - Shiqiong Hu
- Mechanobiology Institute, National University of Singapore, Singapore 117411, Republic of Singapore.,Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Frank Schnorrer
- Aix Marseille University, CNRS, IBDM, 13288 Marseille, France
| | - Samuel A Safran
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Alexander D Bershadsky
- Mechanobiology Institute, National University of Singapore, Singapore 117411, Republic of Singapore .,Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 76100, Israel
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50
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Brynnel A, Hernandez Y, Kiss B, Lindqvist J, Adler M, Kolb J, van der Pijl R, Gohlke J, Strom J, Smith J, Ottenheijm C, Granzier HL. Downsizing the molecular spring of the giant protein titin reveals that skeletal muscle titin determines passive stiffness and drives longitudinal hypertrophy. eLife 2018; 7:40532. [PMID: 30565562 PMCID: PMC6300359 DOI: 10.7554/elife.40532] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Accepted: 11/26/2018] [Indexed: 12/25/2022] Open
Abstract
Titin, the largest protein known, forms an elastic myofilament in the striated muscle sarcomere. To establish titin’s contribution to skeletal muscle passive stiffness, relative to that of the extracellular matrix, a mouse model was created in which titin’s molecular spring region was shortened by deleting 47 exons, the TtnΔ112-158 model. RNA sequencing and super-resolution microscopy predicts a much stiffer titin molecule. Mechanical studies with this novel mouse model support that titin is the main determinant of skeletal muscle passive stiffness. Unexpectedly, the in vivo sarcomere length working range was shifted to shorter lengths in TtnΔ112-158 mice, due to a ~ 30% increase in the number of sarcomeres in series (longitudinal hypertrophy). The expected effect of this shift on active force generation was minimized through a shortening of thin filaments that was discovered in TtnΔ112-158 mice. Thus, skeletal muscle titin is the dominant determinant of physiological passive stiffness and drives longitudinal hypertrophy. Editorial note: This article has been through an editorial process in which the authors decide how to respond to the issues raised during peer review. The Reviewing Editor's assessment is that all the issues have been addressed (see decision letter).
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Affiliation(s)
- Ambjorn Brynnel
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, United States
| | - Yaeren Hernandez
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, United States
| | - Balazs Kiss
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, United States
| | - Johan Lindqvist
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, United States
| | - Maya Adler
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, United States
| | - Justin Kolb
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, United States
| | - Robbert van der Pijl
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, United States
| | - Jochen Gohlke
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, United States
| | - Joshua Strom
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, United States
| | - John Smith
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, United States
| | - Coen Ottenheijm
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, United States
| | - Henk L Granzier
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, United States
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