1
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Stroik D, Gregorich ZR, Raza F, Ge Y, Guo W. Titin: roles in cardiac function and diseases. Front Physiol 2024; 15:1385821. [PMID: 38660537 PMCID: PMC11040099 DOI: 10.3389/fphys.2024.1385821] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2024] [Accepted: 03/25/2024] [Indexed: 04/26/2024] Open
Abstract
The giant protein titin is an essential component of muscle sarcomeres. A single titin molecule spans half a sarcomere and mediates diverse functions along its length by virtue of its unique domains. The A-band of titin functions as a molecular blueprint that defines the length of the thick filaments, the I-band constitutes a molecular spring that determines cell-based passive stiffness, and various domains, including the Z-disk, I-band, and M-line, serve as scaffolds for stretch-sensing signaling pathways that mediate mechanotransduction. This review aims to discuss recent insights into titin's functional roles and their relationship to cardiac function. The role of titin in heart diseases, such as dilated cardiomyopathy and heart failure with preserved ejection fraction, as well as its potential as a therapeutic target, is also discussed.
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Affiliation(s)
- Dawson Stroik
- Cellular and Molecular Pathology Program, Department of Pathology and Laboratory Medicine, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, United States
- Department of Animal and Dairy Sciences, College of Agriculture and Life Science, University of Wisconsin-Madison, Madison, WI, United States
| | - Zachery R. Gregorich
- Department of Animal and Dairy Sciences, College of Agriculture and Life Science, University of Wisconsin-Madison, Madison, WI, United States
| | - Farhan Raza
- Department of Medicine, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, United States
| | - Ying Ge
- Department of Cell and Regenerative Biology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, United States
| | - Wei Guo
- Cellular and Molecular Pathology Program, Department of Pathology and Laboratory Medicine, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, United States
- Department of Animal and Dairy Sciences, College of Agriculture and Life Science, University of Wisconsin-Madison, Madison, WI, United States
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2
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Sharifi H, Mehri M, Mann CK, Campbell KS, Lee LC, Wenk JF. Multiscale Finite Element Modeling of Left Ventricular Growth in Simulations of Valve Disease. Ann Biomed Eng 2024:10.1007/s10439-024-03497-x. [PMID: 38564074 DOI: 10.1007/s10439-024-03497-x] [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: 10/05/2023] [Accepted: 03/18/2024] [Indexed: 04/04/2024]
Abstract
Multiscale models of the cardiovascular system are emerging as effective tools for investigating the mechanisms that drive ventricular growth and remodeling. These models can predict how molecular-level mechanisms impact organ-level structure and function and could provide new insights that help improve patient care. MyoFE is a multiscale computer framework that bridges molecular and organ-level mechanisms in a finite element model of the left ventricle that is coupled with the systemic circulation. In this study, we extend MyoFE to include a growth algorithm, based on volumetric growth theory, to simulate concentric growth (wall thickening/thinning) and eccentric growth (chamber dilation/constriction) in response to valvular diseases. Specifically in our model, concentric growth is controlled by time-averaged total stress along the fiber direction over a cardiac cycle while eccentric growth responds to time-averaged intracellular myofiber passive stress over a cardiac cycle. The new framework correctly predicted different forms of growth in response to two types of valvular diseases, namely aortic stenosis and mitral regurgitation. Furthermore, the model predicted that LV size and function are nearly restored (reversal of growth) when the disease-mimicking perturbation was removed in the simulations for each valvular disorder. In conclusion, the simulations suggest that time-averaged total stress along the fiber direction and time-averaged intracellular myofiber passive stress can be used to drive concentric and eccentric growth in simulations of valve disease.
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Affiliation(s)
- Hossein Sharifi
- Department of Mechanical and Aerospace Engineering, University of Kentucky, 269 Ralph G. Anderson Building, Lexington, KY, 40506-0503, USA
| | - Mohammad Mehri
- Department of Mechanical and Aerospace Engineering, University of Kentucky, 269 Ralph G. Anderson Building, Lexington, KY, 40506-0503, USA
| | - Charles K Mann
- Department of Mechanical and Aerospace Engineering, University of Kentucky, 269 Ralph G. Anderson Building, Lexington, KY, 40506-0503, USA
| | - Kenneth S Campbell
- Division of Cardiovascular Medicine and Department of Physiology, University of Kentucky, Lexington, KY, USA
| | - Lik Chuan Lee
- Department of Mechanical Engineering, Michigan State University, East Lansing, MI, USA
| | - Jonathan F Wenk
- Department of Mechanical and Aerospace Engineering, University of Kentucky, 269 Ralph G. Anderson Building, Lexington, KY, 40506-0503, USA.
- Department of Surgery, University of Kentucky, Lexington, KY, USA.
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3
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Usui Y, Hanashima A, Hashimoto K, Kimoto M, Ohira M, Mohri S. Comparative analysis of ventricular stiffness across species. Physiol Rep 2024; 12:e16013. [PMID: 38644486 PMCID: PMC11033294 DOI: 10.14814/phy2.16013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Revised: 04/01/2024] [Accepted: 04/01/2024] [Indexed: 04/23/2024] Open
Abstract
Investigating ventricular diastolic properties is crucial for understanding the physiological cardiac functions in organisms and unraveling the pathological mechanisms of cardiovascular disorders. Ventricular stiffness, a fundamental parameter that defines ventricular diastolic functions in chordates, is typically analyzed using the end-diastolic pressure-volume relationship (EDPVR). However, comparing ventricular stiffness accurately across chambers of varying maximum volume capacities has been a long-standing challenge. As one of the solutions to this problem, we propose calculating a relative ventricular stiffness index by applying an exponential approximation formula to the EDPVR plot data of the relationship between ventricular pressure and values of normalized ventricular volume by the ventricular weight. This article reviews the potential, utility, and limitations of using normalized EDPVR analysis in recent studies. Herein, we measured and ranked ventricular stiffness in differently sized and shaped chambers using ex vivo ventricular pressure-volume analysis data from four animals: Wistar rats, red-eared slider turtles, masu salmon, and cherry salmon. Furthermore, we have discussed the mechanical effects of intracellular and extracellular viscoelastic components, Titin (Connectin) filaments, collagens, physiological sarcomere length, and other factors that govern ventricular stiffness. Our review provides insights into the comparison of ventricular stiffness in different-sized ventricles between heterologous and homologous species, including non-model organisms.
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Grants
- JP22K15155 Japan Society for the Promotion of Science, Grant/Award Number
- JP20K21453 Japan Society for the Promotion of Science, Grant/Award Number
- JP20H04508 Japan Society for the Promotion of Science, Grant/Award Number
- JP21K19933 Japan Society for the Promotion of Science, Grant/Award Number
- JP20H04521 Japan Society for the Promotion of Science, Grant/Award Number
- JP17H02092 Japan Society for the Promotion of Science, Grant/Award Number
- JP23H00556 Japan Society for the Promotion of Science, Grant/Award Number
- JP17H06272 Japan Society for the Promotion of Science, Grant/Award Number
- JP17H00859 Japan Society for the Promotion of Science, Grant/Award Number
- JP25560214 Japan Society for the Promotion of Science, Grant/Award Number
- JP16K01385 Japan Society for the Promotion of Science, Grant/Award Number
- JP26282127 Japan Society for the Promotion of Science, Grant/Award Number
- The Futaba research grant program
- Research Grant from the Kawasaki Foundation in 2016 from Medical Science and Medical Welfare
- Medical Research Grant in 2010 from Takeda Science Foundation
- R03S005 Research Project Grant from Kawasaki Medical School
- R03B050 Research Project Grant from Kawasaki Medical School
- R01B054 Research Project Grant from Kawasaki Medical School
- H30B041 Research Project Grant from Kawasaki Medical School
- H30B016 Research Project Grant from Kawasaki Medical School
- H27B10 Research Project Grant from Kawasaki Medical School
- R02B039 Research Project Grant from Kawasaki Medical School
- H28B80 Research Project Grant from Kawasaki Medical School
- R05B016 Research Project Grant from Kawasaki Medical School
- Japan Society for the Promotion of Science, Grant/Award Number
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Affiliation(s)
- Yuu Usui
- First Department of PhysiologyKawasaki Medical SchoolKurashikiOkayamaJapan
| | - Akira Hanashima
- First Department of PhysiologyKawasaki Medical SchoolKurashikiOkayamaJapan
| | - Ken Hashimoto
- First Department of PhysiologyKawasaki Medical SchoolKurashikiOkayamaJapan
| | - Misaki Kimoto
- First Department of PhysiologyKawasaki Medical SchoolKurashikiOkayamaJapan
| | - Momoko Ohira
- First Department of PhysiologyKawasaki Medical SchoolKurashikiOkayamaJapan
| | - Satoshi Mohri
- First Department of PhysiologyKawasaki Medical SchoolKurashikiOkayamaJapan
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Silverstein S, Orbach R, Syeda S, Foley AR, Gorokhova S, Meilleur KG, Leach ME, Uapinyoying P, Chao KR, Donkervoort S, Bönnemann CG. Differential inclusion of NEB exons 143 and 144 provides insight into NEB-related myopathy variant interpretation and disease manifestation. MEDRXIV : THE PREPRINT SERVER FOR HEALTH SCIENCES 2024:2024.03.25.24304535. [PMID: 38585796 PMCID: PMC10996755 DOI: 10.1101/2024.03.25.24304535] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/09/2024]
Abstract
Biallelic pathogenic variants in the gene encoding nebulin (NEB) are a known cause of congenital myopathy. We present two individuals with congenital myopathy and compound heterozygous variants (NM_001271208.2: c.2079C>A; p.(Cys693Ter) and c.21522+3A>G ) in NEB. Transcriptomic sequencing on patient muscle revealed that the extended splice variant c.21522+3A>G causes exon 144 skipping. Nebulin isoforms containing exon 144 are known to be mutually exclusive with isoforms containing exon 143, and these isoforms are differentially expressed during development and in adult skeletal muscles. Patients MRIs were compared to the known pattern of relative abundance of these two isoforms in muscle. We propose that the pattern of muscle involvement in these patients better fits the distribution of exon 144-containing isoforms in muscle than with previously published MRI findings in NEB-related disease due to other variants. To our knowledge this is the first report hypothesizing disease pathogenesis through the alteration of isoform distributions in muscle.
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Affiliation(s)
- Sarah Silverstein
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892, USA
- Rutgers New Jersey School of Medicine, 185 S Orange Ave Newark NJ 07103 USA
- Undiagnosed Diseases Program, National Human Genome Research Institute, National Institute of Health, Bethesda, Maryland 20892, USA
| | - Rotem Orbach
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Safoora Syeda
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - A Reghan Foley
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Svetlana Gorokhova
- Aix Marseille Univ, INSERM, MMG, U 1251, Marseille, France
- Department of Medical Genetics, Timone Children’s Hospital, APHM, Marseille, France
| | - Katherine G. Meilleur
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892, USA
- Biogen, Boston MA
| | - Meganne E. Leach
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892, USA
- Division of Neurology, Oregon Health and Science University, 3181 SW Sam Jackson Park Rd, Portland, OR
| | - Prech Uapinyoying
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892, USA
- Research Center for Genetic Medicine, Children’s National Research Institute, Children’s National Medical Center, Washington DC 20010
| | - Katherine R Chao
- Broad Institute of MIT and Harvard, 415 Main St. Cambridge MA 02142
| | - Sandra Donkervoort
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Carsten G. Bönnemann
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892, USA
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5
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Weston TGR, Rees M, Gautel M, Fraternali F. Walking with giants: The challenges of variant impact assessment in the giant sarcomeric protein titin. WIREs Mech Dis 2024; 16:e1638. [PMID: 38155593 DOI: 10.1002/wsbm.1638] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Revised: 12/01/2023] [Accepted: 12/04/2023] [Indexed: 12/30/2023]
Abstract
Titin, the so-called "third filament" of the sarcomere, represents a difficult challenge for the determination of damaging genetic variants. A single titin molecule extends across half the length of a sarcomere in striated muscle, fulfilling a variety of vital structural and signaling roles, and has been linked to an equally varied range of myopathies, resulting in a significant burden on individuals and healthcare systems alike. While the consequences of truncating variants of titin are well-documented, the ramifications of the missense variants prevalent in the general population are less so. We here present a compendium of titin missense variants-those that result in a single amino-acid substitution in coding regions-reported to be pathogenic and discuss these in light of the nature of titin and the variant position within the sarcomere and their domain, the structural, pathological, and biophysical characteristics that define them, and the methods used for characterization. Finally, we discuss the current knowledge and integration of the multiple fields that have contributed to our understanding of titin-related pathology and offer suggestions as to how these concurrent methodologies may aid the further development in our understanding of titin and hopefully extend to other, less well-studied giant proteins. This article is categorized under: Cardiovascular Diseases > Genetics/Genomics/Epigenetics Congenital Diseases > Genetics/Genomics/Epigenetics Congenital Diseases > Molecular and Cellular Physiology.
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Affiliation(s)
- Timir G R Weston
- Randall Centre for Cell & Molecular Biophysics, King's College London, London, UK
| | - Martin Rees
- Randall Centre for Cell & Molecular Biophysics, King's College London, London, UK
| | - Mathias Gautel
- Randall Centre for Cell & Molecular Biophysics, King's College London, London, UK
| | - Franca Fraternali
- Institute of Structural and Molecular Biology, University College London, London, UK
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6
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DePaolo J, Bornstein M, Judy R, Abramowitz S, Verma SS, Levin MG, Arany Z, Damrauer SM. Titin-Truncating variants Predispose to Dilated Cardiomyopathy in Diverse Populations. MEDRXIV : THE PREPRINT SERVER FOR HEALTH SCIENCES 2024:2024.01.17.24301405. [PMID: 38293092 PMCID: PMC10827233 DOI: 10.1101/2024.01.17.24301405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2024]
Abstract
Importance The effect of high percentage spliced in (hiPSI) TTN truncating variants (TTNtvs) on risk of dilated cardiomyopathy (DCM) has historically been studied among population subgroups defined by genetic similarity to European reference populations. This has raised questions about the effect of TTNtvs in diverse populations, especially among individuals genetically similar to African reference populations. Objective To determine the effect of TTNtvs on risk of DCM in diverse population as measured by genetic distance (GD) in principal component (PC) space. Design Cohort study. Setting Penn Medicine Biobank (PMBB) is a large, diverse biobank. Participants Participants were recruited from across the Penn Medicine healthcare system and volunteered to have their electronic health records linked to biospecimen data including DNA which has undergone whole exome sequencing. Main Outcomes and Measures Risk of DCM among individuals carrying a hiPSI TTNtv. Results Carrying a hiPSI TTNtv was associated with DCM among PMBB participants across a range of GD deciles from the 1000G European centroid; the effect estimates ranged from odds ratio (OR) = 3.29 (95% confidence interval [CI] 1.26 to 8.56) to OR = 9.39 (95% CI 3.82 to 23.13). When individuals were assigned to population subgroups based on genetic similarity to the 1000G reference populations, hiPSI TTNtvs conferred significant risk of DCM among those genetically similar to the 1000G European reference population (OR = 7.55, 95% CI 4.99 to 11.42, P<0.001) and individuals genetically similar to the 1000G African reference population (OR 3.50, 95% CI 1.48 to 8.24, P=0.004). Conclusions and Relevance TTNtvs are associated with increased risk of DCM among a diverse cohort. There is no significant difference in effect of TTNtvs on DCM risk across deciles of GD from the 1000G European centroid, suggesting genetic background should not be considered when screening individuals for titin-related DCM.
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Affiliation(s)
- John DePaolo
- Department of Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Marc Bornstein
- Cardiovascular Institute, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, PA 19104, USA
| | - Renae Judy
- Department of Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Sarah Abramowitz
- Department of Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Shefali S Verma
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, PA 19104, USA
| | - Michael G Levin
- Cardiovascular Institute, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, PA 19104, USA
- Corporal Michael J. Crescenz VA Medical Center, Philadelphia, PA 19104, USA
| | - Zoltan Arany
- Cardiovascular Institute, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, PA 19104, USA
| | - Scott M Damrauer
- Department of Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
- Cardiovascular Institute, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, PA 19104, USA
- Corporal Michael J. Crescenz VA Medical Center, Philadelphia, PA 19104, USA
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
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7
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Cizauskas HE, Burnham HV, Panni A, Pena A, Alvarez-Arce A, Davis MT, Araujo KN, Delligatti C, Edassery S, Kirk JA, Arora R, Barefield DY. Proteolytic degradation of atrial sarcomere proteins underlies contractile defects in atrial fibrillation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.05.565691. [PMID: 37961455 PMCID: PMC10635151 DOI: 10.1101/2023.11.05.565691] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
Aims Atrial fibrillation (AFib) is the most common cardiac rhythm disturbance. Treatment of AFib involves restoration of the atrial electrical rhythm. Following rhythm restoration, a period of depressed mechanical function known as atrial stunning occurs that involves decreased blood flow velocity and reduced atrial contractility. This suggests that defects in contractility occur in AFib and are revealed upon restoration of rhythm. The aim of this project is to define the contractile remodeling that occurs in AFib. Methods and Results To assess contractile function, we used a canine atrial tachypacing model of induced AFib. Mass spectrometry analysis showed dysregulation of contractile proteins in samples from AFib compared to sinus rhythm atria. Atrial cardiomyocytes showed reduced force of contraction in skinned single cardiomyocyte calcium-force studies. There were no significant differences in myosin heavy chain isoform expression. Resting tension is decreased in the AFib samples correlating with reduced full-length titin in the sarcomere. We measured degradation of other myofilament proteins including cMyBP-C, actinin, and cTnI, showing significant degradation in the AFib samples compared to sinus rhythm atria. Many of the protein degradation products appeared as discrete cleavage products that are generated by calpain proteolysis. We assessed calpain activity and found it to be significantly increased. Skinned cardiomyocytes from AFib atria showed decreased troponin I phosphorylation, consistent with the increased calcium sensitivity that was found within these cardiomyocytes. Conclusions With these results it can be concluded that AFib causes alterations in contraction that can be explained by both molecular changes occurring in myofilament proteins and overall myofilament protein degradation. These results provide an understanding of the contractile remodeling that occurs in AFib and provides insight into the molecular explanation for atrial stunning and the increased risk of atrial thrombus and stroke in AFib.
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8
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Lloyd EM, Pinniger GJ, Murphy RM, Grounds MD. Slow or fast: Implications of myofibre type and associated differences for manifestation of neuromuscular disorders. Acta Physiol (Oxf) 2023; 238:e14012. [PMID: 37306196 DOI: 10.1111/apha.14012] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Revised: 05/30/2023] [Accepted: 06/06/2023] [Indexed: 06/13/2023]
Abstract
Many neuromuscular disorders can have a differential impact on a specific myofibre type, forming the central premise of this review. The many different skeletal muscles in mammals contain a spectrum of slow- to fast-twitch myofibres with varying levels of protein isoforms that determine their distinctive contractile, metabolic, and other properties. The variations in functional properties across the range of classic 'slow' to 'fast' myofibres are outlined, combined with exemplars of the predominantly slow-twitch soleus and fast-twitch extensor digitorum longus muscles, species comparisons, and techniques used to study these properties. Other intrinsic and extrinsic differences are discussed in the context of slow and fast myofibres. These include inherent susceptibility to damage, myonecrosis, and regeneration, plus extrinsic nerves, extracellular matrix, and vasculature, examined in the context of growth, ageing, metabolic syndrome, and sexual dimorphism. These many differences emphasise the importance of carefully considering the influence of myofibre-type composition on manifestation of various neuromuscular disorders across the lifespan for both sexes. Equally, understanding the different responses of slow and fast myofibres due to intrinsic and extrinsic factors can provide deep insight into the precise molecular mechanisms that initiate and exacerbate various neuromuscular disorders. This focus on the influence of different myofibre types is of fundamental importance to enhance translation for clinical management and therapies for many skeletal muscle disorders.
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Affiliation(s)
- Erin M Lloyd
- Department of Anatomy, Physiology and Human Biology, School of Human Sciences, The University of Western Australia, Perth, Western Australia, Australia
- Curtin Health Innovation Research Institute, Curtin Medical School, Curtin University, Bentley, Western Australia, Australia
| | - Gavin J Pinniger
- Department of Anatomy, Physiology and Human Biology, School of Human Sciences, The University of Western Australia, Perth, Western Australia, Australia
| | - Robyn M Murphy
- Department of Biochemistry and Chemistry, School of Agriculture, Biomedicine and Environment, La Trobe University, Melbourne, Victoria, Australia
| | - Miranda D Grounds
- Department of Anatomy, Physiology and Human Biology, School of Human Sciences, The University of Western Australia, Perth, Western Australia, Australia
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9
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Gotthardt M, Badillo-Lisakowski V, Parikh VN, Ashley E, Furtado M, Carmo-Fonseca M, Schudy S, Meder B, Grosch M, Steinmetz L, Crocini C, Leinwand L. Cardiac splicing as a diagnostic and therapeutic target. Nat Rev Cardiol 2023; 20:517-530. [PMID: 36653465 DOI: 10.1038/s41569-022-00828-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 12/09/2022] [Indexed: 01/19/2023]
Abstract
Despite advances in therapeutics for heart failure and arrhythmias, a substantial proportion of patients with cardiomyopathy do not respond to interventions, indicating a need to identify novel modifiable myocardial pathobiology. Human genetic variation associated with severe forms of cardiomyopathy and arrhythmias has highlighted the crucial role of alternative splicing in myocardial health and disease, given that it determines which mature RNA transcripts drive the mechanical, structural, signalling and metabolic properties of the heart. In this Review, we discuss how the analysis of cardiac isoform expression has been facilitated by technical advances in multiomics and long-read and single-cell sequencing technologies. The resulting insights into the regulation of alternative splicing - including the identification of cardiac splice regulators as therapeutic targets and the development of a translational pipeline to evaluate splice modulators in human engineered heart tissue, animal models and clinical trials - provide a basis for improved diagnosis and therapy. Finally, we consider how the medical and scientific communities can benefit from facilitated acquisition and interpretation of splicing data towards improved clinical decision-making and patient care.
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Affiliation(s)
- Michael Gotthardt
- Neuromuscular and Cardiovascular Cell Biology, Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany.
- DZHK (German Center for Cardiovascular Research Partner Site Berlin), Berlin, Germany.
- Department of Cardiology, Charité - Universitätsmedizin Berlin, Berlin, Germany.
| | - Victor Badillo-Lisakowski
- Neuromuscular and Cardiovascular Cell Biology, Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany
- DZHK (German Center for Cardiovascular Research Partner Site Berlin), Berlin, Germany
| | - Victoria Nicole Parikh
- Stanford Center for Inherited Cardiovascular Disease, Stanford University School of Medicine, Palo Alto, CA, USA
| | - Euan Ashley
- Stanford Center for Inherited Cardiovascular Disease, Stanford University School of Medicine, Palo Alto, CA, USA
- Stanford Genome Technology Center, Stanford University, Palo Alto, CA, USA
- Department of Genetics, School of Medicine, Stanford University, Stanford, CA, USA
| | - Marta Furtado
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
| | - Maria Carmo-Fonseca
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
| | - Sarah Schudy
- Institute for Cardiomyopathies, Department of Medicine III, University of Heidelberg, Heidelberg, Germany
| | - Benjamin Meder
- Institute for Cardiomyopathies, Department of Medicine III, University of Heidelberg, Heidelberg, Germany
- DZHK (German Center for Cardiovascular Research Partner Site Heidelberg-Mannheim), Heidelberg, Germany
| | - Markus Grosch
- European Molecular Biology Laboratory (EMBL), Genome Biology Unit, Heidelberg, Germany
| | - Lars Steinmetz
- Stanford Genome Technology Center, Stanford University, Palo Alto, CA, USA
- Department of Genetics, School of Medicine, Stanford University, Stanford, CA, USA
- European Molecular Biology Laboratory (EMBL), Genome Biology Unit, Heidelberg, Germany
| | - Claudia Crocini
- Department of Molecular, Cellular, and Developmental Biology and BioFrontiers Institute, University of Colorado, Boulder, CO, USA
| | - Leslie Leinwand
- Department of Molecular, Cellular, and Developmental Biology and BioFrontiers Institute, University of Colorado, Boulder, CO, USA
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10
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Baban A, Cicenia M, Magliozzi M, Parlapiano G, Cirillo M, Pascolini G, Fattori F, Gnazzo M, Bruno P, De Luca L, Di Chiara L, Francalanci P, Udd B, Secinaro A, Amodeo A, Bertini ES, Savarese M, Drago F, Novelli A. Biallelic truncating variants in children with titinopathy represent a recognizable condition with distinctive muscular and cardiac characteristics: a report on five patients. Front Cardiovasc Med 2023; 10:1210378. [PMID: 37576110 PMCID: PMC10415037 DOI: 10.3389/fcvm.2023.1210378] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2023] [Accepted: 07/10/2023] [Indexed: 08/15/2023] Open
Abstract
Background Monoallelic and biallelic TTN truncating variants (TTNtv) may be responsible for a wide spectrum of musculoskeletal and cardiac disorders with different age at onset. Although the prevalence of heterozygous TTNtv is relatively high in the general population, cardiac phenotyping (mainly cardiomyopathies, CMPs) in biallelic titinopathy has rarely been described in children. Methods We reviewed the medical records of pediatric patients with biallelic TTNtv and cardiac involvement. Clinical exome sequencing excluded pathogenic/likely pathogenic variants in major CMP genes. Results Five pediatric patients (four male) with biallelic TTNtv were included. Major arthrogryposis multiplex was observed in four patients; no patient showed intellectual disability. At a cardiac level, congenital heart defects (atrial and ventricular septal defects, n = 3) and left ventricular non-compaction (n = 1) were reported. All patients had dilated cardiomyopathy (DCM) diagnosed at birth in one patient and at the age of 10, 13, 14, and 17 years in the other four patients. Heart rhythm monitoring showed tachyarrhythmias (premature ventricular contractions, n = 2; non-sustained ventricular tachycardia, n = 2) and nocturnal first-degree atrio-ventricular block (n = 2). Cardiac magnetic resonance (CMR) imaging was performed in all patients and revealed a peculiar late gadolinium enhancement distribution in three patients. HyperCKemia was present in two patients and end-stage heart failure in four. End-organ damage requiring heart transplantation (HT) was indicated in two patients, who were operated on successfully. Conclusion Biallelic TTNtv should be considered when evaluating children with severe and early-onset DCM, particularly if skeletal and muscular abnormalities are present, e.g., arthrogryposis multiplex and congenital progressive myopathy. End-stage heart failure is common and may require HT.
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Affiliation(s)
- Anwar Baban
- Pediatric Cardiology and Arrhythmia/Syncope Complex Unit, Bambino Gesù Children’s Hospital, IRCCS, Rome, Italy
| | - Marianna Cicenia
- Pediatric Cardiology and Arrhythmia/Syncope Complex Unit, Bambino Gesù Children’s Hospital, IRCCS, Rome, Italy
| | - Monia Magliozzi
- Laboratory of Medical Genetics, Translational Cytogenomics Research Unit, Bambino Gesù Children’s Hospital, IRCCS, Rome, Italy
| | - Giovanni Parlapiano
- Pediatric Cardiology and Arrhythmia/Syncope Complex Unit, Bambino Gesù Children’s Hospital, IRCCS, Rome, Italy
- Laboratory of Medical Genetics, Translational Cytogenomics Research Unit, Bambino Gesù Children’s Hospital, IRCCS, Rome, Italy
| | - Marco Cirillo
- Department of Imaging, Bambino Gesù Children’s Hospital, IRCCS, Rome, Italy
| | - Giulia Pascolini
- Pediatric Cardiology and Arrhythmia/Syncope Complex Unit, Bambino Gesù Children’s Hospital, IRCCS, Rome, Italy
- Laboratory of Medical Genetics, Translational Cytogenomics Research Unit, Bambino Gesù Children’s Hospital, IRCCS, Rome, Italy
| | - Fabiana Fattori
- Unit of Muscular and Neurodegenerative Disorders, Bambino Gesù Children’s Hospital, IRCCS, Rome, Italy
| | - Maria Gnazzo
- Translational Cytogenomics Research Unit, Bambino Gesù Children’s Hospital, Rome, Italy
| | - Pasqualina Bruno
- Department of Cardiac Surgery, Cardiology, Heart and Lung Transplantation, Bambino Gesù Children’s Hospital, IRCCS, Rome, Italy
| | - Lorenzo De Luca
- Pediatric Cardiology and Arrhythmia/Syncope Complex Unit, Bambino Gesù Children’s Hospital, IRCCS, Rome, Italy
| | - Luca Di Chiara
- Pediatric Cardiac Intensive Care Unit, Department of Cardiology and Cardiac Surgery, Bambino Gesù Children’s Hospital, IRCCS, Rome, Italy
| | - Paola Francalanci
- Department of Pathology, Bambino Gesù Children’s Hospital and Research Institute, IRCCS, Rome, Italy
| | - Bjarne Udd
- Folkhälsan Research Center, Helsinki, Finland
- Department of Medical Genetics, Medicum, University of Helsinki, Helsinki, Finland
- Department of Neurology, Vaasa Central Hospital, Vaasa, Finland
| | - Aurelio Secinaro
- Advanced Cardiothoracic Imaging Unit, Bambino Gesù Children’s Hospital, IRCCS, Rome, Italy
| | - Antonio Amodeo
- Heart Failureand Transplant, Mechanical Circulatory Support Complex Unit, Bambino Gesù Children’s Hospital, IRCCS, Rome, Italy
| | - Enrico Silvio Bertini
- Unit of Muscular and Neurodegenerative Disorders, Bambino Gesù Children’s Hospital, IRCCS, Rome, Italy
| | - Marco Savarese
- Folkhälsan Research Center, Helsinki, Finland
- Department of Medical Genetics, Medicum, University of Helsinki, Helsinki, Finland
| | - Fabrizio Drago
- Pediatric Cardiology and Arrhythmia/Syncope Complex Unit, Bambino Gesù Children’s Hospital, IRCCS, Rome, Italy
| | - Antonio Novelli
- Laboratory of Medical Genetics, Translational Cytogenomics Research Unit, Bambino Gesù Children’s Hospital, IRCCS, Rome, Italy
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11
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Alawneh I, Yuki KE, Amburgey K, Yoon G, Dowling JJ, Hazrati LN, Gonorazky H. Titin related myopathy with ophthalmoplegia. A novel phenotype. Neuromuscul Disord 2023; 33:605-609. [PMID: 37393749 DOI: 10.1016/j.nmd.2023.05.003] [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: 01/26/2023] [Revised: 05/01/2023] [Accepted: 05/11/2023] [Indexed: 07/04/2023]
Abstract
Titin-related myopathy is an emerging genetic neuromuscular disorder with a wide spectrum of clinical phenotypes. To date, there have not been reports of patients with this disease that presented with extraocular muscle involvement. Here we discuss a 19-year-old male with congenital weakness, complete ophthalmoplegia, thoracolumbar scoliosis, and obstructive sleep apnea. Muscle magnetic resonance imaging revealed severe involvement of the gluteal and anterior compartment muscles, and clear adductor sparing, while muscle biopsy of the right vastus lateralis showed distinctive cap-like structures. Trio Whole Exome Sequencing (WES) showed compound heterozygous likely pathologic variants in the TTN gene. (c.82541_82544dup (p.Arg27515Serfs*2) in exon 327 (NM_001267550.2) and c.31846+1G>A (p.?) in exon 123 (NM_001267550.2). To our knowledge, this is the first report of a TTN-related disorder associated with ophthalmoplegia.
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Affiliation(s)
- Issa Alawneh
- Division of Neurology, The Hospital for Sick Children, University of Toronto, Toronto, Canada
| | - Kyoko E Yuki
- Division of Genome Diagnostics, The Hospital for Sick Children, University of Toronto, Toronto, Canada
| | - Kimberly Amburgey
- Division of Neurology, The Hospital for Sick Children, University of Toronto, Toronto, Canada; Division of Genome Diagnostics, The Hospital for Sick Children, University of Toronto, Toronto, Canada
| | - Grace Yoon
- Division of Neurology, The Hospital for Sick Children, University of Toronto, Toronto, Canada; Division of Genetic, The Hospital for Sick Children, University of Toronto, Toronto, Canada
| | - James J Dowling
- Division of Neurology, The Hospital for Sick Children, University of Toronto, Toronto, Canada; Division of Genetic, The Hospital for Sick Children, University of Toronto, Toronto, Canada; Program of Genetic and Genome Biology, The Hospital for Sick Children, University of Toronto, Toronto, Canada
| | - Lili-Naz Hazrati
- Division of Pathology, The Hospital for Sick Children, University of Toronto, Toronto, Canada
| | - Hernan Gonorazky
- Division of Neurology, The Hospital for Sick Children, University of Toronto, Toronto, Canada; Program of Genetic and Genome Biology, The Hospital for Sick Children, University of Toronto, Toronto, Canada.
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12
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Banga S, Cardoso R, Castellani C, Srivastava S, Watkins J, Lima J. Cardiac MRI as an Imaging Tool in Titin Variant-Related Dilated Cardiomyopathy. CARDIOVASCULAR REVASCULARIZATION MEDICINE 2023; 52:86-93. [PMID: 36934006 DOI: 10.1016/j.carrev.2023.03.001] [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: 11/07/2022] [Revised: 02/05/2023] [Accepted: 03/01/2023] [Indexed: 03/08/2023]
Abstract
Dilated Cardiomyopathy is a common myocardial disease characterized by dilation and loss of function of one or both ventricles. A variety of etiologies have been implicated including genetic variation. Advancement in genetic sequencing, and diagnostic imaging allows for detection of genetic mutations in sarcomere protein titin (TTN) and high resolution assessment of cardiac function. This review article discusses the role of cardiac MRI in diagnosing dilated cardiomyopathy in patients with TTN variant related cardiomyopathy.
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Affiliation(s)
- Sandeep Banga
- Division of Cardiology, Michigan State University, Sparrow Hospital, Lansing, MI, USA.
| | | | - Carson Castellani
- Division of Internal Medicine, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Shaurya Srivastava
- Division of Internal Medicine, Michigan State University, Lansing, MI, USA
| | - Jennifer Watkins
- Division of Cardiology, Michigan State University, Sparrow Hospital, Lansing, MI, USA
| | - Joao Lima
- Division of Cardiology, Johns Hopkins University, Baltimore, MD, USA
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13
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Chakraborty AD, Kooiker K, Kobak KA, Cheng Y, Lee CF, Razumova M, Granzier H H, Regnier M, Rabinovitch PS, Moussavi-Harami F, Chiao YA. Late-life Rapamycin Treatment Enhances Cardiomyocyte Relaxation Kinetics and Reduces Myocardial Stiffness. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.12.544619. [PMID: 37398078 PMCID: PMC10312630 DOI: 10.1101/2023.06.12.544619] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
Diastolic dysfunction is a key feature of the aging heart. We have shown that late-life treatment with mTOR inhibitor, rapamycin, reverses age-related diastolic dysfunction in mice but the molecular mechanisms of the reversal remain unclear. To dissect the mechanisms by which rapamycin improves diastolic function in old mice, we examined the effects of rapamycin treatment at the levels of single cardiomyocyte, myofibril and multicellular cardiac muscle. Compared to young cardiomyocytes, isolated cardiomyocytes from old control mice exhibited prolonged time to 90% relaxation (RT 90 ) and time to 90% Ca 2+ transient decay (DT 90 ), indicating slower relaxation kinetics and calcium reuptake with age. Late-life rapamycin treatment for 10 weeks completely normalized RT 90 and partially normalized DT 90 , suggesting improved Ca 2+ handling contributes partially to the rapamycin-induced improved cardiomyocyte relaxation. In addition, rapamycin treatment in old mice enhanced the kinetics of sarcomere shortening and Ca 2+ transient increase in old control cardiomyocytes. Myofibrils from old rapamycin-treated mice displayed increased rate of the fast, exponential decay phase of relaxation compared to old controls. The improved myofibrillar kinetics were accompanied by an increase in MyBP-C phosphorylation at S282 following rapamycin treatment. We also showed that late-life rapamycin treatment normalized the age-related increase in passive stiffness of demembranated cardiac trabeculae through a mechanism independent of titin isoform shift. In summary, our results showed that rapamycin treatment normalizes the age-related impairments in cardiomyocyte relaxation, which works conjointly with reduced myocardial stiffness to reverse age-related diastolic dysfunction.
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14
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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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15
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Eccentric muscle contractions: from single muscle fibre to whole muscle mechanics. Pflugers Arch 2023; 475:421-435. [PMID: 36790515 PMCID: PMC10011336 DOI: 10.1007/s00424-023-02794-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Revised: 01/24/2023] [Accepted: 02/01/2023] [Indexed: 02/16/2023]
Abstract
Eccentric muscle loading encompasses several unique features compared to other types of contractions. These features include increased force, work, and performance at decreased oxygen consumption, reduced metabolic cost, improved energy efficiency, as well as decreased muscle activity. This review summarises explanatory approaches to long-standing questions in terms of muscular contraction dynamics and molecular and cellular mechanisms underlying eccentric muscle loading. Moreover, this article intends to underscore the functional link between sarcomeric components, emphasising the fundamental role of titin in skeletal muscle. The giant filament titin reveals versatile functions ranging from sarcomere organisation and maintenance, providing passive tension and elasticity, and operates as a mechanosensory and signalling platform. Structurally, titin consists of a viscoelastic spring segment that allows activation-dependent coupling to actin. This titin-actin interaction can explain linear force increases in active lengthening experiments in biological systems. A three-filament model of skeletal muscle force production (mediated by titin) is supposed to overcome significant deviations between experimental observations and predictions by the classic sliding-filament and cross-bridge theories. Taken together, this review intends to contribute to a more detailed understanding of overall muscle behaviour and force generation-from a microscopic sarcomere level to a macroscopic multi-joint muscle level-impacting muscle modelling, the understanding of muscle function, and disease.
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16
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Usui Y, Kimoto M, Hanashima A, Hashimoto K, Mohri S. Cardiac hemodynamics and ventricular stiffness of sea-run cherry salmon (Oncorhynchus masou masou) differ critically from those of landlocked masu salmon. PLoS One 2022; 17:e0267264. [PMID: 36331913 PMCID: PMC9635730 DOI: 10.1371/journal.pone.0267264] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Accepted: 10/25/2022] [Indexed: 11/06/2022] Open
Abstract
Ventricular diastolic mechanical properties are important determinants of cardiac function and are optimized by changes in cardiac structure and physical properties. Oncorhynchus masou masou is an anadromous migratory fish of the Salmonidae family, and several ecological studies on it have been conducted; however, the cardiac functions of the fish are not well known. Therefore, we investigated ventricular diastolic function in landlocked (masu salmon) and sea-run (cherry salmon) types at 29–30 months post fertilization. Pulsed-wave Doppler echocardiography showed that the atrioventricular inflow waveforms of cherry salmon were biphasic with early diastolic filling and atrial contraction, whereas those of masu salmon were monophasic with atrial contraction. In addition, end-diastolic pressure–volume relationship analysis revealed that the dilatability per unit myocardial mass of the ventricle in cherry salmon was significantly suppressed compared to that in masu salmon, suggesting that the ventricle of the cherry salmon was relatively stiffer (relative ventricular stiffness index; p = 0.0263). Contrastingly, the extensibility of cardiomyocytes, characterized by the expression pattern of Connectin isoforms in their ventricles, was similar in both types. Histological analysis showed that the percentage of the collagen accumulation area in the compact layer of cherry salmon increased compared with that of the masu salmon, which may contribute to ventricle stiffness. Although the heart mass of cherry salmon was about 11-fold greater than that of masu salmon, there was no difference in the morphology of the isolated cardiomyocytes, suggesting that the heart of the cherry salmon grows by cardiomyocyte proliferation, but not cell hypertrophy. The cardiac physiological function of the teleosts varies with differences in their developmental processes and life history. Our multidimensional analysis of the O. masou heart may provide a clue to the process by which the heart acquires a biphasic blood-filling pattern, i.e., a ventricular diastolic suction.
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Affiliation(s)
- Yuu Usui
- First Department of Physiology, Kawasaki Medical School, Kurashiki, Japan
- * E-mail:
| | - Misaki Kimoto
- First Department of Physiology, Kawasaki Medical School, Kurashiki, Japan
| | - Akira Hanashima
- First Department of Physiology, Kawasaki Medical School, Kurashiki, Japan
| | - Ken Hashimoto
- First Department of Physiology, Kawasaki Medical School, Kurashiki, Japan
| | - Satoshi Mohri
- First Department of Physiology, Kawasaki Medical School, Kurashiki, Japan
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17
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Averdunk L, Donkervoort S, Horn D, Waldmüller S, Syeda S, Neuhaus SB, Chao KR, van Riesen A, Gauck D, Haack T, Japp AS, Lee U, Bönnemann CG, Mayatepek E, Distelmaier F. Recognizable Pattern of Arthrogryposis and Congenital Myopathy Caused by the Recurrent TTN Metatranscript-only c.39974-11T > G Splice Variant. Neuropediatrics 2022; 53:309-320. [PMID: 35605965 DOI: 10.1055/a-1859-0800] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
INTRODUCTION Arthrogryposis is characterized by the presence of multiple contractures at birth and can be caused by pathogenic variants in TTN (Titin). Exons and variants that are not expressed in one of the three major isoforms of titin are referred to as "metatranscript-only" and have been considered to be only expressed during fetal development. Recently, the metatranscript-only variant (c.39974-11T > G) in TTN with a second truncating TTN variant has been linked to arthrogryposis multiplex congenita and myopathy. METHODS Via exome sequencing we identified the TTN c.39974-11T > G splice variant in trans with one of three truncating variants (p.Arg8922*, p.Lys32998Asnfs*63, p.Tyr10345*) in five individuals from three families. Clinical presentation and muscle ultrasound as well as MRI images were analyzed. RESULTS All five patients presented with generalized muscular hypotonia, reduced muscle bulk, and congenital contractures most prominently affecting the upper limbs and distal joints. Muscular hypotonia persisted and contractures improved over time. One individual, the recipient twin in the setting of twin-to-twin transfusion syndrome, died from severe cardiac hypertrophy 1 day after birth. Ultrasound and MRI imaging studies revealed a recognizable pattern of muscle involvement with striking fibrofatty involvement of the hamstrings and calves, and relative sparing of the femoral adductors and anterior segment of the thighs. CONCLUSION The recurrent TTN c.39974-11T > G variant consistently causes congenital arthrogryposis and persisting myopathy providing evidence that the metatranscript-only 213 to 217 exons impact muscle elasticity during early development and beyond. There is a recognizable pattern of muscle involvement, which is distinct from other myopathies and provides valuable clues for diagnostic work-up.
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Affiliation(s)
- Luisa Averdunk
- Department of General Pediatrics, Neonatology and Pediatric Cardiology, Medical Faculty, Heinrich-Heine-University, University Hospital, Düsseldorf, Germany
| | - Sandra Donkervoort
- Neuromuscular and Neurogenetic Disorders of Childhood Section, Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, United States
| | - Denise Horn
- Institute of Medical Genetics and Human Genetics, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Stephan Waldmüller
- Institute of Medical Genetics and Applied Genomics, University of Tuebingen, Tuebingen, Germany
| | - Safoora Syeda
- Institute of Medical Genetics and Human Genetics, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Sarah B Neuhaus
- Neuromuscular and Neurogenetic Disorders of Childhood Section, Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, United States
| | - Katherine R Chao
- Center for Mendelian Genomics, Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, Massachusetts, United States
| | - Anne van Riesen
- Center for Chronically Sick Children, Charité - Universitätsmedizin Berlin, Berlin, Germany.,Department of Pediatric Neurology, University Medical Center Göttingen, Göttingen, Germany
| | - Darja Gauck
- Institute of Medical Genetics and Applied Genomics, University of Tuebingen, Tuebingen, Germany
| | - Tobias Haack
- Institute of Medical Genetics and Applied Genomics, University of Tuebingen, Tuebingen, Germany
| | - Anna S Japp
- Institute of Pathology, University Hospital Düsseldorf, Düsseldorf, Germany
| | - Unaa Lee
- Department of General Pediatrics, Neonatology and Pediatric Cardiology, Medical Faculty, Heinrich-Heine-University, University Hospital, Düsseldorf, Germany
| | - Carsten G Bönnemann
- Neuromuscular and Neurogenetic Disorders of Childhood Section, Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, United States
| | - Ertan Mayatepek
- Department of General Pediatrics, Neonatology and Pediatric Cardiology, Medical Faculty, Heinrich-Heine-University, University Hospital, Düsseldorf, Germany
| | - Felix Distelmaier
- Department of General Pediatrics, Neonatology and Pediatric Cardiology, Medical Faculty, Heinrich-Heine-University, University Hospital, Düsseldorf, Germany
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18
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Leońska-Duniec A, Borczyk M, Piechota M, Korostyński M, Brodkiewicz A, Cięszczyk P. TTN Variants Are Associated with Physical Performance and Provide Potential Markers for Sport-Related Phenotypes. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2022; 19:10173. [PMID: 36011809 PMCID: PMC9408402 DOI: 10.3390/ijerph191610173] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Revised: 08/12/2022] [Accepted: 08/15/2022] [Indexed: 06/15/2023]
Abstract
TTN encodes the third myofilament, titin, which plays structural, mechanical, regulatory, and developmental roles in sarcomeres. The aim of this research was to determine the interaction between novel and previously described TTN variants and athletic performance, as well as competition level, in Caucasians. Firstly, 100 athletes and 47 controls were recruited, and whole-genome sequencing was performed. Secondly, 348 athletes (108 endurance, 100 sprint/power, 140 mixed-sport athletes) and 403 volunteers were included, and real-time PCR was performed. We found a significant overrepresentation of the rs10497520 CT and TT genotypes in the sprint/power athlete group (95% CI, 1.41-3.66, p = 0.0013). The rs10497520 T carriers were 2.17 times more likely to become sprint/power athletes (95% CI 1.35-3.49, p = 0.0021). We also found that the likelihood of having the TT genotype was higher for the highly elite and sub-elite sprint/power athletes. Possessing at least one TAA (rs10497520, rs55837610, rs72648256) haplotype resulted in an increase in the log-odds ratio by 0.80 (p = 0.0015), 1.42 (p = 0.003), and 0.77 (p = 0.044) for all, highly elite, and sub-elite sprint/power athletes, respectively. We demonstrated that harbouring the rs10497520 T allele, individually and in a haplotype combination, increased the chance of being an elite sprint/power athlete, indicating that this allele may be favourable for sprint/power performance.
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Affiliation(s)
- Agata Leońska-Duniec
- Faculty of Physical Education, Gdansk University of Physical Education and Sport, 80-336 Gdansk, Poland
| | - Małgorzata Borczyk
- Laboratory of Pharmacogenomics, Department of Molecular Neuropharmacology, Maj Institute of Pharmacology, Polish Academy of Sciences, 31-343 Kraków, Poland
| | - Marcin Piechota
- Laboratory of Pharmacogenomics, Department of Molecular Neuropharmacology, Maj Institute of Pharmacology, Polish Academy of Sciences, 31-343 Kraków, Poland
| | - Michał Korostyński
- Laboratory of Pharmacogenomics, Department of Molecular Neuropharmacology, Maj Institute of Pharmacology, Polish Academy of Sciences, 31-343 Kraków, Poland
| | - Andrzej Brodkiewicz
- Department of Pediatrics, Child Nephrology, Dialisotherapy and Management of Acute Poisoning, Pomeranian Medical University, 70-204 Szczecin, Poland
| | - Paweł Cięszczyk
- Faculty of Physical Education, Gdansk University of Physical Education and Sport, 80-336 Gdansk, Poland
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19
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Contributions of Titin and Collagen to Passive Stress in Muscles from mdm Mice with a Small Deletion in Titin’s Molecular Spring. Int J Mol Sci 2022; 23:ijms23168858. [PMID: 36012129 PMCID: PMC9408699 DOI: 10.3390/ijms23168858] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Revised: 08/01/2022] [Accepted: 08/07/2022] [Indexed: 12/12/2022] Open
Abstract
Muscular dystrophy with myositis (mdm) is a naturally occurring mutation in the mouse Ttn gene that results in higher passive stress in muscle fibers and intact muscles compared to wild-type (WT). The goal of this study was to test whether alternative splicing of titin exons occurs in mdm muscles, which contain a small deletion in the N2A-PEVK regions of titin, and to test whether splicing changes are associated with an increase in titin-based passive tension. Although higher levels of collagen have been reported previously in mdm muscles, here we demonstrate alternative splicing of titin in mdm skeletal muscle fibers. We identified Z-band, PEVK, and C-terminus Mex5 exons as splicing hotspots in mdm titin using RNA sequencing data and further reported upregulation in ECM-associated genes. We also treated skinned mdm soleus fiber bundles with trypsin, trypsin + KCl, and trypsin + KCL + KI to degrade titin. The results showed that passive stress dropped significantly more after trypsin treatment in mdm fibers (11 ± 1.6 mN/mm2) than in WT fibers (4.8 ± 1 mN/mm2; p = 0.0004). The finding that treatment with trypsin reduces titin-based passive tension more in mdm than in WT fibers supports the hypothesis that exon splicing leads to the expression of a stiffer and shorter titin isoform in mdm fibers. After titin extraction by trypsin + KCl + KI, mdm fibers (6.7 ± 1.27 mN/mm2) had significantly higher collagen-based passive stress remaining than WT fibers (2.6 ± 1.3 mN/mm2; p = 0.0014). We conclude that both titin and collagen contribute to higher passive tension of mdm muscles.
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20
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Hurley KL, Bassett JR, Monroy JA. Active muscle stiffness is reduced during rapid unloading in muscles from TtnD112-158 mice with a large deletion to PEVK titin. J Exp Biol 2022; 225:276067. [DOI: 10.1242/jeb.243584] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Accepted: 07/13/2022] [Indexed: 11/20/2022]
Abstract
Evidence suggests that the giant muscle protein, titin functions as a tunable spring in active muscle. However, the mechanisms for increasing titin stiffness with activation are not well understood. Previous studies have suggested that during muscle activation, titin binds to actin which engages the PEVK region of titin thereby increasing titin stiffness. In this study, we investigated the role of PEVK titin in active muscle stiffness during rapid unloading. We measured elastic recoil of active and passive soleus muscles from TtnD112-158 mice characterized by a 75% deletion of PEVK titin and increased passive stiffness. We hypothesized that activated TtnD112-158 muscles are more stiff than wild type muscles due to the increased stiffness of PEVK titin. Using a servomotor force lever, we compared the stress–strain relationships of elastic elements in active and passive muscles during rapid unloading and quantified the change in stiffness upon activation. Results show that the elastic modulus of TtnD112-158 muscles increased with activation. However, elastic elements developed force at 7% longer lengths and exhibited 50% lower active stiffness in TtnD112-158 soleus muscles than wild type muscles. Thus, despite having a shorter, stiffer PEVK segment, during rapid unloading, TtnD112-158 soleus muscles exhibited reduced active stiffness compared to wild type soleus muscles. These results are consistent with the idea that PEVK titin contributes to active muscle stiffness, however, the reduction in active stiffness of TtnD112-158 muscles suggests that other mechanisms compensate for the increased PEVK stiffness.
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Affiliation(s)
| | | | - Jenna A. Monroy
- 3 W.M. Keck Science Department, Claremont Colleges, Claremont, CA, USA
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21
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Kötter S, Krüger M. Protein Quality Control at the Sarcomere: Titin Protection and Turnover and Implications for Disease Development. Front Physiol 2022; 13:914296. [PMID: 35846001 PMCID: PMC9281568 DOI: 10.3389/fphys.2022.914296] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Accepted: 06/10/2022] [Indexed: 11/26/2022] Open
Abstract
Sarcomeres are mainly composed of filament and signaling proteins and are the smallest molecular units of muscle contraction and relaxation. The sarcomere protein titin serves as a molecular spring whose stiffness mediates myofilament extensibility in skeletal and cardiac muscle. Due to the enormous size of titin and its tight integration into the sarcomere, the incorporation and degradation of the titin filament is a highly complex task. The details of the molecular processes involved in titin turnover are not fully understood, but the involvement of different intracellular degradation mechanisms has recently been described. This review summarizes the current state of research with particular emphasis on the relationship between titin and protein quality control. We highlight the involvement of the proteasome, autophagy, heat shock proteins, and proteases in the protection and degradation of titin in heart and skeletal muscle. Because the fine-tuned balance of degradation and protein expression can be disrupted under pathological conditions, the review also provides an overview of previously known perturbations in protein quality control and discusses how these affect sarcomeric proteins, and titin in particular, in various disease states.
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22
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Li N, Hang W, Shu H, Zhou N. RBM20, a Therapeutic Target to Alleviate Myocardial Stiffness via Titin Isoforms Switching in HFpEF. Front Cardiovasc Med 2022; 9:928244. [PMID: 35783855 PMCID: PMC9243441 DOI: 10.3389/fcvm.2022.928244] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Accepted: 05/30/2022] [Indexed: 12/05/2022] Open
Abstract
Increased myocardial stiffness is critically involved in heart diseases with impaired cardiac compliance, especially heart failure with preserved ejection fraction (HFpEF). Myocardial stiffness mainly derives from cardiomyocyte- and extracellular matrix (ECM)-derived passive stiffness. Titin, a major component of sarcomeres, participates in myocardial passive stiffness and stress-sensitive signaling. The ratio of two titin isoforms, N2BA to N2B, was validated to influence diastolic dysfunction via several pathways. RNA binding motif protein 20 (RBM20) is a well-studied splicing factor of titin, functional deficiency of RBM20 in mice profile improved cardiac compliance and function, which indicated that RBM20 functions as a potential therapeutic target for mitigating myocardial stiffness by modulating titin isoforms. This minor review summarized how RBM20 and other splicing factors modify the titin isoforms ratio, therefore providing a promising target for improving the myocardial compliance of HFpEF.
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23
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Herrero-Galán E, Martínez-Martín I, Sánchez-González C, Vicente N, Bonzón-Kulichenko E, Calvo E, Suay-Corredera C, Pricolo MR, Fernández-Trasancos Á, Velázquez-Carreras D, Careaga CB, Abdellatif M, Sedej S, Rainer PP, Giganti D, Pérez-Jiménez R, Vázquez J, Alegre-Cebollada J. Basal oxidation of conserved cysteines modulates cardiac titin stiffness and dynamics. Redox Biol 2022; 52:102306. [PMID: 35367810 PMCID: PMC8971355 DOI: 10.1016/j.redox.2022.102306] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Revised: 03/24/2022] [Accepted: 03/25/2022] [Indexed: 01/11/2023] Open
Abstract
Titin, as the main protein responsible for the passive stiffness of the sarcomere, plays a key role in diastolic function and is a determinant factor in the etiology of heart disease. Titin stiffness depends on unfolding and folding transitions of immunoglobulin-like (Ig) domains of the I-band, and recent studies have shown that oxidative modifications of cryptic cysteines belonging to these Ig domains modulate their mechanical properties in vitro. However, the relevance of this mode of titin mechanical modulation in vivo remains largely unknown. Here, we describe the high evolutionary conservation of titin mechanical cysteines and show that they are remarkably oxidized in murine cardiac tissue. Mass spectrometry analyses indicate a similar landscape of basal oxidation in murine and human myocardium. Monte Carlo simulations illustrate how disulfides and S-thiolations on these cysteines increase the dynamics of the protein at physiological forces, while enabling load- and isoform-dependent regulation of titin stiffness. Our results demonstrate the role of conserved cysteines in the modulation of titin mechanical properties in vivo and point to potential redox-based pathomechanisms in heart disease.
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Affiliation(s)
| | | | | | - Natalia Vicente
- Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain
| | - Elena Bonzón-Kulichenko
- Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain; CIBER de Enfermedades Cardiovasculares (CIBERCV), Madrid, Spain
| | - Enrique Calvo
- Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain; CIBER de Enfermedades Cardiovasculares (CIBERCV), Madrid, Spain
| | | | | | | | | | | | | | - Simon Sedej
- Division of Cardiology, Medical University of Graz, Graz, Austria; Faculty of Medicine, University of Maribor, Maribor, Slovenia; BioTechMed Graz, Graz, Austria
| | - Peter P Rainer
- Division of Cardiology, Medical University of Graz, Graz, Austria; BioTechMed Graz, Graz, Austria
| | - David Giganti
- Department of Biochemistry & Molecular Pharmacology and Institute for Systems Genetics, NYU Langone Health, New York, NY, United States
| | - Raúl Pérez-Jiménez
- CIC NanoGUNE BRTA, San Sebastian, Spain; Ikerbasque Foundation for Science, Bilbao, Spain
| | - Jesús Vázquez
- Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain; CIBER de Enfermedades Cardiovasculares (CIBERCV), Madrid, Spain
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24
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Herzog W. What Can We Learn from Single Sarcomere and Myofibril Preparations? Front Physiol 2022; 13:837611. [PMID: 35574477 PMCID: PMC9092595 DOI: 10.3389/fphys.2022.837611] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Accepted: 04/06/2022] [Indexed: 11/13/2022] Open
Abstract
Sarcomeres are the smallest functional contractile unit of muscle, and myofibrils are striated muscle organelles that are comprised of sarcomeres that are strictly aligned in series. Furthermore, passive forces in sarcomeres and myofibrils are almost exclusively produced by the structural protein titin, and all contractile, regulatory, and structural proteins are in their natural configuration. For these mechanical and structural reasons single sarcomere and myofibril preparations are arguably the most powerful to answer questions on the mechanisms of striated muscle contraction. We developed and optimized single myofibril research over the past 20 years and were the first to mechanically isolate and test single sarcomeres. The results from this research led to the uncovering of the crucial role of titin in muscle contraction, first molecular explanations for the origins of the passive and the residual force enhancement properties of skeletal and cardiac muscles, the discovery of sarcomere length stability on the descending limb of the force-length relationship, and culminating in the formulation of the three-filament theory of muscle contraction that, aside from actin and myosin, proposes a crucial role of titin in active force production. Aside from all the advantages and possibilities that single sarcomere and myofibril preparations offer, there are also disadvantages. These include the fragility of the preparation, the time-consuming training to master these preparations, the limited spatial resolution for length and force measurements, and the unavailability of commercial systems for single sarcomere/myofibril research. Ignoring the mechanics that govern serially linked systems, not considering the spatial resolution and associated accuracies of myofibril systems, and neglecting the fragility of myofibril preparations, has led to erroneous interpretations of results and misleading conclusions. Here, we will attempt to describe the methods and possible applications of single sarcomere/myofibril research and discuss the advantages and disadvantages by focusing on specific applications. It is hoped that this discussion may contribute to identifying the enormous potential of single sarcomere/myofibril research in discovering the secrets of muscle contraction.
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Affiliation(s)
- Walter Herzog
- Faculty of Kinesiology, The University of Calgary, Calgary, AB, Canada
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25
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Mishra D, Nishikawa KC. Residual force enhancement is reduced in permeabilized fiber bundles from mdm muscles. J Exp Biol 2022; 225:275519. [PMID: 35514253 DOI: 10.1242/jeb.243732] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2021] [Accepted: 04/28/2022] [Indexed: 11/20/2022]
Abstract
Residual force enhancement (RFE) is the increase in steady-state force after active stretch relative to the force during isometric contraction at the same final length. The mdm mutation in mice, characterized by a small deletion in N2A titin, has been proposed to prevent N2A titin-actin interactions so that active mdm muscles are more compliant than WT. This decrease in active muscle stiffness is associated with reduced RFE. We investigated RFE in permeabilized soleus (SOL) and extensor digitorum longus (EDL) fiber bundles from wild type and mdm mice. On each fiber bundle, we performed active and passive stretches from an average sarcomere length of 2.6 - 3.0 µm at a slow rate of 0.04 µm/s, as well as isometric contractions at the initial and final lengths. One-way ANOVA showed that SOL and EDL fiber bundles from mdm mice exhibited significantly lower RFE than WT (P<0.0001). This result is consistent with previous observations in single myofibrils and intact muscles. However, it contradicts the results from a previous study which appeared to show that compensatory mechanisms could restore titin force enhancement in single fibers from mdm psoas. We suggest that residual force enhancement measured previously in mdm single fibers was an artifact of the high variability in passive tension found in degenerating fibers, which begins after ∼24 days of age. The results are consistent with the hypothesis that RFE is reduced in mdm skeletal muscles due to impaired Ca2+ dependent titin-actin interactions resulting from the small deletion in N2A titin.
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Affiliation(s)
- Dhruv Mishra
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, USA
| | - Kiisa C Nishikawa
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, USA
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26
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The Cardiomyocyte in Heart Failure with Preserved Ejection Fraction—Victim of Its Environment? Cells 2022; 11:cells11050867. [PMID: 35269489 PMCID: PMC8909081 DOI: 10.3390/cells11050867] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Accepted: 03/01/2022] [Indexed: 12/07/2022] Open
Abstract
Heart failure (HF) with preserved left ventricular ejection fraction (HFpEF) is becoming the predominant form of HF. However, medical therapy that improves cardiovascular outcome in HF patients with almost normal and normal systolic left ventricular function, but diastolic dysfunction is missing. The cause of this unmet need is incomplete understanding of HFpEF pathophysiology, the heterogeneity of the patient population, and poor matching of therapeutic mechanisms and primary pathophysiological processes. Recently, animal models improved understanding of the pathophysiological role of highly prevalent and often concomitantly presenting comorbidity in HFpEF patients. Evidence from these animal models provide first insight into cellular pathophysiology not considered so far in HFpEF disease, promising that improved understanding may provide new therapeutical targets. This review merges observation from animal models and human HFpEF disease with the intention to converge cardiomyocytes pathophysiological aspects and clinical knowledge.
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27
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In heart failure reactivation of RNA-binding proteins is associated with the expression of 1,523 fetal-specific isoforms. PLoS Comput Biol 2022; 18:e1009918. [PMID: 35226669 PMCID: PMC8912908 DOI: 10.1371/journal.pcbi.1009918] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Revised: 03/10/2022] [Accepted: 02/10/2022] [Indexed: 01/03/2023] Open
Abstract
Reactivation of fetal-specific genes and isoforms occurs during heart failure. However, the underlying molecular mechanisms and the extent to which the fetal program switch occurs remains unclear. Limitations hindering transcriptome-wide analyses of alternative splicing differences (i.e. isoform switching) in cardiovascular system (CVS) tissues between fetal, healthy adult and heart failure have included both cellular heterogeneity across bulk RNA-seq samples and limited availability of fetal tissue for research. To overcome these limitations, we have deconvoluted the cellular compositions of 996 RNA-seq samples representing heart failure, healthy adult (heart and arteria), and fetal-like (iPSC-derived cardiovascular progenitor cells) CVS tissues. Comparison of the expression profiles revealed that reactivation of fetal-specific RNA-binding proteins (RBPs), and the accompanied re-expression of 1,523 fetal-specific isoforms, contribute to the transcriptome differences between heart failure and healthy adult heart. Of note, isoforms for 20 different RBPs were among those that reverted in heart failure to the fetal-like expression pattern. We determined that, compared with adult-specific isoforms, fetal-specific isoforms encode proteins that tend to have more functions, are more likely to harbor RBP binding sites, have canonical sequences at their splice sites, and contain typical upstream polypyrimidine tracts. Our study suggests that compared with healthy adult, fetal cardiac tissue requires stricter transcriptional regulation, and that during heart failure reversion to this stricter transcriptional regulation occurs. Furthermore, we provide a resource of cardiac developmental stage-specific and heart failure-associated genes and isoforms, which are largely unexplored and can be exploited to investigate novel therapeutics for heart failure. Heart failure is a chronic condition in which the heart does not pump enough blood. It has been shown that in heart failure, the adult heart reverts to a fetal-like metabolic state and oxygen consumption. Additionally, genes and isoforms that are expressed in the heart only during fetal development (i.e. not in the healthy adult heart) are turned on in heart failure. However, the underlying molecular mechanisms and the extent to which the switch to a fetal gene program occurs remains unclear. In this study, we initially characterized the differences between the fetal and adult heart transcriptomes (entire set of expressed genes and isoforms). We found that RNA binding proteins (RBPs), a family of genes that regulate multiple aspects of a transcript’s maturation, including transcription, splicing and post-transcriptional modifications, play a central role in the differences between fetal and adult heart tissues. We observed that many RBPs that are only expressed in the heart during fetal development become reactivated in heart failure, resulting in the expression of 1,523 fetal-specific isoforms. These findings suggest that reactivation of fetal-specific RBPs in heart failure drives a transcriptome-wide switch to expression of fetal-specific isoforms; and hence that RBPs could potentially serve as novel therapeutic targets.
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28
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Mahdavi M, Mohsen-Pour N, Maleki M, Hesami M, Naderi N, Houshmand G, Rasouli Jazi HR, Shahzadi H, Kalayinia S. Whole-exome sequencing identified compound heterozygous variants in the TTN gene causing Salih myopathy with dilated cardiomyopathy in an Iranian family. Cardiol Young 2021; 32:1-6. [PMID: 34782032 DOI: 10.1017/s1047951121004455] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
BACKGROUND Salih myopathy, characterised by both congenital myopathy and fatal dilated cardiomyopathy, is an inherited muscle disorder that affects skeletal and cardiac muscles. TTN has been identified as the main cause of this myopathy, the enormous size of this gene poses a formidable challenge to molecular genetic diagnostics. METHOD In the present study, whole-exome sequencing, cardiac MRI, and metabolic parameter assessment were performed to investigate the genetic causes of Salih myopathy in a consanguineous Iranian family who presented with titinopathy involving both skeletal and heart muscles in an autosomal recessive inheritance pattern. RESULTS Two missense variants of TTN gene (NM_001267550.2), namely c.61280A>C (p. Gln20427Pro) and c.54970G>A (p. Gly18324Ser), were detected and segregations were confirmed by polymerase chain reaction-based Sanger sequencing. CONCLUSIONS The compound heterozygous variants, c.61280A>C, (p. Gln20427Pro) and c.54970G>A, (p. Gly18324Ser) in the TTN gene appear to be the cause of Salih myopathy and dilated cardiomyopathy in the family presented. Whole-exome sequencing is an effective molecular diagnostic tool to identify the causative genetic variants of large genes such as TTN.
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Affiliation(s)
- Mohammad Mahdavi
- Cardiogenetic Research Center, Rajaie Cardiovascular Medical and Research Center, Iran University of Medical Sciences, Tehran, Iran
| | - Neda Mohsen-Pour
- Zanjan Pharmaceutical Biotechnology Research Center, Zanjan University of Medical Sciences, Zanjan, Iran
| | - Majid Maleki
- Cardiogenetic Research Center, Rajaie Cardiovascular Medical and Research Center, Iran University of Medical Sciences, Tehran, Iran
| | - Mahshid Hesami
- Rajaie Cardiovascular Medical and Research Center, Iran University of Medical Sciences, Tehran, Iran
| | - Niloofar Naderi
- Cardiogenetic Research Center, Rajaie Cardiovascular Medical and Research Center, Iran University of Medical Sciences, Tehran, Iran
| | - Golnaz Houshmand
- Rajaie Cardiovascular Medical and Research Center, Iran University of Medical Sciences, Tehran, Iran
| | - Hamid R Rasouli Jazi
- Biotechnology Research Center, Malek Ashtar University of Technology, Tehran, Iran
| | - Hossein Shahzadi
- Rajaie Cardiovascular Medical and Research Center, Iran University of Medical Sciences, Tehran, Iran
| | - Samira Kalayinia
- Cardiogenetic Research Center, Rajaie Cardiovascular Medical and Research Center, Iran University of Medical Sciences, Tehran, Iran
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29
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van der Pijl RJ, Domenighetti AA, Sheikh F, Ehler E, Ottenheijm CAC, Lange S. The titin N2B and N2A regions: biomechanical and metabolic signaling hubs in cross-striated muscles. Biophys Rev 2021; 13:653-677. [PMID: 34745373 PMCID: PMC8553726 DOI: 10.1007/s12551-021-00836-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Accepted: 08/23/2021] [Indexed: 02/07/2023] Open
Abstract
Muscle specific signaling has been shown to originate from myofilaments and their associated cellular structures, including the sarcomeres, costameres or the cardiac intercalated disc. Two signaling hubs that play important biomechanical roles for cardiac and/or skeletal muscle physiology are the N2B and N2A regions in the giant protein titin. Prominent proteins associated with these regions in titin are chaperones Hsp90 and αB-crystallin, members of the four-and-a-half LIM (FHL) and muscle ankyrin repeat protein (Ankrd) families, as well as thin filament-associated proteins, such as myopalladin. This review highlights biological roles and properties of the titin N2B and N2A regions in health and disease. Special emphasis is placed on functions of Ankrd and FHL proteins as mechanosensors that modulate muscle-specific signaling and muscle growth. This region of the sarcomere also emerged as a hotspot for the modulation of passive muscle mechanics through altered titin phosphorylation and splicing, as well as tethering mechanisms that link titin to the thin filament system.
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Affiliation(s)
| | - Andrea A. Domenighetti
- Shirley Ryan AbilityLab, Chicago, IL USA
- Department of Physical Medicine and Rehabilitation, Northwestern University, Chicago, IL USA
| | - Farah Sheikh
- Division of Cardiology, School of Medicine, UC San Diego, La Jolla, CA USA
| | - Elisabeth Ehler
- Randall Centre for Cell and Molecular Biophysics, School of Cardiovascular Medicine and Sciences, King’s College London, London, UK
| | - Coen A. C. Ottenheijm
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ USA
- Department of Physiology, Amsterdam University Medical Centers, Amsterdam, The Netherlands
| | - Stephan Lange
- Division of Cardiology, School of Medicine, UC San Diego, La Jolla, CA USA
- Department of Molecular and Clinical Medicine, University of Gothenburg, Gothenburg, Sweden
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30
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Loescher CM, Hobbach AJ, Linke WA. Titin (TTN): from molecule to modifications, mechanics and medical significance. Cardiovasc Res 2021; 118:2903-2918. [PMID: 34662387 PMCID: PMC9648829 DOI: 10.1093/cvr/cvab328] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Accepted: 10/13/2021] [Indexed: 12/19/2022] Open
Abstract
The giant sarcomere protein titin is a major determinant of cardiomyocyte stiffness and contributor to cardiac strain sensing. Titin-based forces are highly regulated in health and disease, which aids in the regulation of myocardial function, including cardiac filling and output. Due to the enormous size, complexity, and malleability of the titin molecule, titin properties are also vulnerable to dysregulation, as observed in various cardiac disorders. This review provides an overview of how cardiac titin properties can be changed at a molecular level, including the role isoform diversity and post-translational modifications (acetylation, oxidation, and phosphorylation) play in regulating myocardial stiffness and contractility. We then consider how this regulation becomes unbalanced in heart disease, with an emphasis on changes in titin stiffness and protein quality control. In this context, new insights into the key pathomechanisms of human cardiomyopathy due to a truncation in the titin gene (TTN) are discussed. Along the way, we touch on the potential for titin to be therapeutically targeted to treat acquired or inherited cardiac conditions, such as HFpEF or TTN-truncation cardiomyopathy.
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Affiliation(s)
- Christine M Loescher
- Institute of Physiology II, University Hospital Münster, Robert-Koch-Str. 27B, Münster, 48149 Germany
| | - Anastasia J Hobbach
- Department of Cardiology I, Coronary, Peripheral Vascular Disease and Heart Failure, University Hospital Münster, Münster, Germany
| | - Wolfgang A Linke
- Institute of Physiology II, University Hospital Münster, Robert-Koch-Str. 27B, Münster, 48149 Germany
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31
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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: 1] [Impact Index Per Article: 0.3] [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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32
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Huang K, Duan HQ, Li QX, Luo YB, Bi FF, Yang H. Clinicopathological features of titinopathy from a Chinese neuromuscular center. Neuropathology 2021; 41:349-356. [PMID: 34553419 DOI: 10.1111/neup.12761] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Revised: 05/17/2021] [Accepted: 05/18/2021] [Indexed: 12/14/2022]
Abstract
Titin, one of the largest proteins in humans, is a major component of muscle sarcomeres. Pathogenic variants in the titin gene (TTN) have been reported to cause a range of skeletal muscle diseases, collectively known as titinopathy. Titinopathy is a heterogeneous group of disabling diseases characterized by muscle weakness. In our study, we aimed to establish the clinicopathological-genetic spectrum of titinopathy from a single neuromuscular center. Three patients were diagnosed as having definite titinopathy, and additional three patients were diagnosed as having possible titinopathy according to the diagnostic criteria. All the patients showed initial symptoms from age one to 40 years. Physical examination revealed that five patients had muscle weakness, and that one patient experienced behavioral changes. Muscle biopsy specimens obtained from all six patients demonstrated multiple myopathological changes, including increased fiber size variation, muscle fiber hypertrophy or atrophy, formation of centralized cell nuclei, necklace cytoplasmic bodies, and formation of rimmed vacuoles and cores. Genetic testing revealed 11 different TTN alterations, including missense (6/11), nonsense (2/11), frameshift (2/11), and splicing (1/11) mutations. Our study provides further evidence that TTN mutations are more likely to be responsible for an increasing proportion of various myopathies, such as hereditary myopathy with early respiratory failure (HMERF), core myopathy, and distal myopathy with rimmed vacuoles, than currently recognized mutations. Our findings expand the clinical, pathohistological and genetic spectrum of titinopathy.
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Affiliation(s)
- Kun Huang
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, China
| | - Hui-Qian Duan
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, China
| | - Qiu-Xiang Li
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, China
| | - Yue-Bei Luo
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, China
| | - Fang-Fang Bi
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, China
| | - Huan Yang
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, China
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33
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Biquand A, Spinozzi S, Tonino P, Cosette J, Strom J, Elbeck Z, Knöll R, Granzier H, Lostal W, Richard I. Titin M-line insertion sequence 7 is required for proper cardiac function in mice. J Cell Sci 2021; 134:271843. [PMID: 34401916 DOI: 10.1242/jcs.258684] [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: 03/25/2021] [Accepted: 08/06/2021] [Indexed: 11/20/2022] Open
Abstract
Titin is a giant sarcomeric protein that is involved in a large number of functions, with a primary role in skeletal and cardiac sarcomere organization and stiffness. The titin gene (TTN) is subject to various alternative splicing events, but in the region that is present at the M-line, the only exon that can be spliced out is Mex5, which encodes for the insertion sequence 7 (is7). Interestingly, in the heart, the majority of titin isoforms are Mex5+, suggesting a cardiac role for is7. Here, we performed comprehensive functional, histological, transcriptomic, microscopic and molecular analyses of a mouse model lacking the Ttn Mex5 exon (ΔMex5), and revealed that the absence of the is7 is causative for dilated cardiomyopathy. ΔMex5 mice showed altered cardiac function accompanied by increased fibrosis and ultrastructural alterations. Abnormal expression of excitation-contraction coupling proteins was also observed. The results reported here confirm the importance of the C-terminal region of titin in cardiac function and are the first to suggest a possible relationship between the is7 and excitation-contraction coupling. Finally, these findings give important insights for the identification of new targets in the treatment of titinopathies.
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Affiliation(s)
- Ariane Biquand
- Genethon, 91000 Evry, France.,Université Paris-Saclay, Univ Evry, Inserm, Généthon, Integrare research unit UMR_S951, 91000 Evry-Courcouronnes, France
| | - Simone Spinozzi
- Genethon, 91000 Evry, France.,Université Paris-Saclay, Univ Evry, Inserm, Généthon, Integrare research unit UMR_S951, 91000 Evry-Courcouronnes, France
| | - Paola Tonino
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85721, USA
| | | | - Joshua Strom
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85721, USA
| | - Zaher Elbeck
- Department of Medicine, Integrated Cardio Metabolic Centre (ICMC), Heart and Vascular Theme, Karolinska Institutet, 141 57 Huddinge, Sweden
| | - Ralph Knöll
- Department of Medicine, Integrated Cardio Metabolic Centre (ICMC), Heart and Vascular Theme, Karolinska Institutet, 141 57 Huddinge, Sweden.,Bioscience Cardiovascular, Research and Early Development, Cardiovascular, Renal and Metabolism (CVRM), BioPharmaceuticals R&D, AstraZeneca, 431 50 Gothenburg, Sweden
| | - Henk Granzier
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85721, USA
| | - William Lostal
- Genethon, 91000 Evry, France.,Université Paris-Saclay, Univ Evry, Inserm, Généthon, Integrare research unit UMR_S951, 91000 Evry-Courcouronnes, France
| | - Isabelle Richard
- Genethon, 91000 Evry, France.,Université Paris-Saclay, Univ Evry, Inserm, Généthon, Integrare research unit UMR_S951, 91000 Evry-Courcouronnes, France
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Alegre-Cebollada J. Protein nanomechanics in biological context. Biophys Rev 2021; 13:435-454. [PMID: 34466164 PMCID: PMC8355295 DOI: 10.1007/s12551-021-00822-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Accepted: 07/05/2021] [Indexed: 12/20/2022] Open
Abstract
How proteins respond to pulling forces, or protein nanomechanics, is a key contributor to the form and function of biological systems. Indeed, the conventional view that proteins are able to diffuse in solution does not apply to the many polypeptides that are anchored to rigid supramolecular structures. These tethered proteins typically have important mechanical roles that enable cells to generate, sense, and transduce mechanical forces. To fully comprehend the interplay between mechanical forces and biology, we must understand how protein nanomechanics emerge in living matter. This endeavor is definitely challenging and only recently has it started to appear tractable. Here, I introduce the main in vitro single-molecule biophysics methods that have been instrumental to investigate protein nanomechanics over the last 2 decades. Then, I present the contemporary view on how mechanical force shapes the free energy of tethered proteins, as well as the effect of biological factors such as post-translational modifications and mutations. To illustrate the contribution of protein nanomechanics to biological function, I review current knowledge on the mechanobiology of selected muscle and cell adhesion proteins including titin, talin, and bacterial pilins. Finally, I discuss emerging methods to modulate protein nanomechanics in living matter, for instance by inducing specific mechanical loss-of-function (mLOF). By interrogating biological systems in a causative manner, these new tools can contribute to further place protein nanomechanics in a biological context.
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35
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Huerta-López C, Alegre-Cebollada J. Protein Hydrogels: The Swiss Army Knife for Enhanced Mechanical and Bioactive Properties of Biomaterials. NANOMATERIALS (BASEL, SWITZERLAND) 2021; 11:1656. [PMID: 34202469 PMCID: PMC8307158 DOI: 10.3390/nano11071656] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 06/17/2021] [Accepted: 06/18/2021] [Indexed: 12/31/2022]
Abstract
Biomaterials are dynamic tools with many applications: from the primitive use of bone and wood in the replacement of lost limbs and body parts, to the refined involvement of smart and responsive biomaterials in modern medicine and biomedical sciences. Hydrogels constitute a subtype of biomaterials built from water-swollen polymer networks. Their large water content and soft mechanical properties are highly similar to most biological tissues, making them ideal for tissue engineering and biomedical applications. The mechanical properties of hydrogels and their modulation have attracted a lot of attention from the field of mechanobiology. Protein-based hydrogels are becoming increasingly attractive due to their endless design options and array of functionalities, as well as their responsiveness to stimuli. Furthermore, just like the extracellular matrix, they are inherently viscoelastic in part due to mechanical unfolding/refolding transitions of folded protein domains. This review summarizes different natural and engineered protein hydrogels focusing on different strategies followed to modulate their mechanical properties. Applications of mechanically tunable protein-based hydrogels in drug delivery, tissue engineering and mechanobiology are discussed.
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Affiliation(s)
- Carla Huerta-López
- Centro Nacional de Investigaciones Cardiovasculares (CNIC), 28029 Madrid, Spain
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36
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van der Pijl RJ, van den Berg M, van de Locht M, Shen S, Bogaards SJP, Conijn S, Langlais P, Hooijman PE, Labeit S, Heunks LMA, Granzier H, Ottenheijm CAC. Muscle ankyrin repeat protein 1 (MARP1) locks titin to the sarcomeric thin filament and is a passive force regulator. J Gen Physiol 2021; 153:212403. [PMID: 34152365 PMCID: PMC8222902 DOI: 10.1085/jgp.202112925] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Accepted: 05/19/2021] [Indexed: 12/12/2022] Open
Abstract
Muscle ankyrin repeat protein 1 (MARP1) is frequently up-regulated in stressed muscle, but its effect on skeletal muscle function is poorly understood. Here, we focused on its interaction with the titin–N2A element, found in titin’s molecular spring region. We show that MARP1 binds to F-actin, and that this interaction is stronger when MARP1 forms a complex with titin–N2A. Mechanics and super-resolution microscopy revealed that MARP1 “locks” titin–N2A to the sarcomeric thin filament, causing increased extension of titin’s elastic PEVK element and, importantly, increased passive force. In support of this mechanism, removal of thin filaments abolished the effect of MARP1 on passive force. The clinical relevance of this mechanism was established in diaphragm myofibers of mechanically ventilated rats and of critically ill patients. Thus, MARP1 regulates passive force by locking titin to the thin filament. We propose that in stressed muscle, this mechanism protects the sarcomere from mechanical damage.
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Affiliation(s)
- Robbert J van der Pijl
- Department of Physiology, Amsterdam University Medical Centers, Amsterdam, Netherlands.,Department of Cellular and Molecular Medicine, University of Arizona, Tuscon, AZ
| | - Marloes van den Berg
- Department of Physiology, Amsterdam University Medical Centers, Amsterdam, Netherlands.,Department of Cellular and Molecular Medicine, University of Arizona, Tuscon, AZ
| | - Martijn van de Locht
- Department of Physiology, Amsterdam University Medical Centers, Amsterdam, Netherlands
| | - Shengyi Shen
- Department of Cellular and Molecular Medicine, University of Arizona, Tuscon, AZ
| | - Sylvia J P Bogaards
- Department of Physiology, Amsterdam University Medical Centers, Amsterdam, Netherlands
| | - Stefan Conijn
- Department of Physiology, Amsterdam University Medical Centers, Amsterdam, Netherlands
| | - Paul Langlais
- Division of Endocrinology, University of Arizona, Tucson, AZ
| | - Pleuni E Hooijman
- Department of Physiology, Amsterdam University Medical Centers, Amsterdam, Netherlands
| | - Siegfried Labeit
- Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
| | - Leo M A Heunks
- Intensive Care Medicine, Amsterdam University Medical Centers, Amsterdam, Netherlands
| | - Henk Granzier
- Department of Cellular and Molecular Medicine, University of Arizona, Tuscon, AZ
| | - Coen A C Ottenheijm
- Department of Physiology, Amsterdam University Medical Centers, Amsterdam, Netherlands.,Department of Cellular and Molecular Medicine, University of Arizona, Tuscon, AZ
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Abstract
PURPOSE OF REVIEW This review aims to give an update on recent findings related to the cardiac splicing factor RNA-binding motif protein 20 (RBM20) and RBM20 cardiomyopathy, a form of dilated cardiomyopathy caused by mutations in RBM20. RECENT FINDINGS While most research on RBM20 splicing targets has focused on titin (TTN), multiple studies over the last years have shown that other splicing targets of RBM20 including Ca2+/calmodulin-dependent kinase IIδ (CAMK2D) might be critically involved in the development of RBM20 cardiomyopathy. In this regard, loss of RBM20 causes an abnormal intracellular calcium handling, which may relate to the arrhythmogenic presentation of RBM20 cardiomyopathy. In addition, RBM20 presents clinically in a highly gender-specific manner, with male patients suffering from an earlier disease onset and a more severe disease progression. Further research on RBM20, and treatment of RBM20 cardiomyopathy, will need to consider both the multitude and relative contribution of the different splicing targets and related pathways, as well as gender differences.
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Münch J, Abdelilah-Seyfried S. Sensing and Responding of Cardiomyocytes to Changes of Tissue Stiffness in the Diseased Heart. Front Cell Dev Biol 2021; 9:642840. [PMID: 33718383 PMCID: PMC7952448 DOI: 10.3389/fcell.2021.642840] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Accepted: 02/09/2021] [Indexed: 12/20/2022] Open
Abstract
Cardiomyocytes are permanently exposed to mechanical stimulation due to cardiac contractility. Passive myocardial stiffness is a crucial factor, which defines the physiological ventricular compliance and volume of diastolic filling with blood. Heart diseases often present with increased myocardial stiffness, for instance when fibrotic changes modify the composition of the cardiac extracellular matrix (ECM). Consequently, the ventricle loses its compliance, and the diastolic blood volume is reduced. Recent advances in the field of cardiac mechanobiology revealed that disease-related environmental stiffness changes cause severe alterations in cardiomyocyte cellular behavior and function. Here, we review the molecular mechanotransduction pathways that enable cardiomyocytes to sense stiffness changes and translate those into an altered gene expression. We will also summarize current knowledge about when myocardial stiffness increases in the diseased heart. Sophisticated in vitro studies revealed functional changes, when cardiomyocytes faced a stiffer matrix. Finally, we will highlight recent studies that described modulations of cardiac stiffness and thus myocardial performance in vivo. Mechanobiology research is just at the cusp of systematic investigations related to mechanical changes in the diseased heart but what is known already makes way for new therapeutic approaches in regenerative biology.
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Affiliation(s)
- Juliane Münch
- Institute of Biochemistry and Biology, University of Potsdam, Potsdam, Germany
| | - Salim Abdelilah-Seyfried
- Institute of Biochemistry and Biology, University of Potsdam, Potsdam, Germany.,Institute of Molecular Biology, Hannover Medical School, Hannover, Germany
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39
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Thomas SL, Thacker JB, Schug KA, Maráková K. Sample preparation and fractionation techniques for intact proteins for mass spectrometric analysis. J Sep Sci 2020; 44:211-246. [DOI: 10.1002/jssc.202000936] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Revised: 10/28/2020] [Accepted: 10/29/2020] [Indexed: 12/17/2022]
Affiliation(s)
- Shannon L. Thomas
- Department of Chemistry & Biochemistry The University of Texas Arlington Arlington Texas USA
| | - Jonathan B. Thacker
- Department of Chemistry & Biochemistry The University of Texas Arlington Arlington Texas USA
| | - Kevin A. Schug
- Department of Chemistry & Biochemistry The University of Texas Arlington Arlington Texas USA
| | - Katarína Maráková
- Department of Pharmaceutical Analysis and Nuclear Pharmacy Faculty of Pharmacy Comenius University in Bratislava Bratislava Slovakia
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40
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Lostal W, Roudaut C, Faivre M, Charton K, Suel L, Bourg N, Best H, Smith JE, Gohlke J, Corre G, Li X, Elbeck Z, Knöll R, Deschamps JY, Granzier H, Richard I. Titin splicing regulates cardiotoxicity associated with calpain 3 gene therapy for limb-girdle muscular dystrophy type 2A. Sci Transl Med 2020; 11:11/520/eaat6072. [PMID: 31776291 DOI: 10.1126/scitranslmed.aat6072] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Accepted: 10/31/2019] [Indexed: 01/31/2023]
Abstract
Limb-girdle muscular dystrophy type 2A (LGMD2A or LGMDR1) is a neuromuscular disorder caused by mutations in the calpain 3 gene (CAPN3). Previous experiments using adeno-associated viral (AAV) vector-mediated calpain 3 gene transfer in mice indicated cardiac toxicity associated with the ectopic expression of the calpain 3 transgene. Here, we performed a preliminary dose study in a severe double-knockout mouse model deficient in calpain 3 and dysferlin. We evaluated safety and biodistribution of AAV9-desmin-hCAPN3 vector administration to nonhuman primates (NHPs) with a dose of 3 × 1013 viral genomes/kg. Vector administration did not lead to observable adverse effects or to detectable toxicity in NHP. Of note, the transgene expression did not produce any abnormal changes in cardiac morphology or function of injected animals while reaching therapeutic expression in skeletal muscle. Additional investigation on the underlying causes of cardiac toxicity observed after gene transfer in mice and the role of titin in this phenomenon suggest species-specific titin splicing. Mice have a reduced capacity for buffering calpain 3 activity compared to NHPs and humans. Our studies highlight a complex interplay between calpain 3 and titin binding sites and demonstrate an effective and safe profile for systemic calpain 3 vector delivery in NHP, providing critical support for the clinical potential of calpain 3 gene therapy in humans.
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Affiliation(s)
- William Lostal
- Généthon INSERM, U951, INTEGRARE Research Unit, Evry F-91002, France
| | - Carinne Roudaut
- Généthon INSERM, U951, INTEGRARE Research Unit, Evry F-91002, France
| | - Marine Faivre
- Généthon INSERM, U951, INTEGRARE Research Unit, Evry F-91002, France
| | - Karine Charton
- Généthon INSERM, U951, INTEGRARE Research Unit, Evry F-91002, France
| | - Laurence Suel
- Généthon INSERM, U951, INTEGRARE Research Unit, Evry F-91002, France
| | - Nathalie Bourg
- Généthon INSERM, U951, INTEGRARE Research Unit, Evry F-91002, France
| | - Heather Best
- Généthon INSERM, U951, INTEGRARE Research Unit, Evry F-91002, France
| | | | | | - Guillaume Corre
- Généthon INSERM, U951, INTEGRARE Research Unit, Evry F-91002, France
| | - Xidan Li
- Department of Medicine, Karolinska Institute, Stockholm SE-171 77, Sweden
| | - Zaher Elbeck
- Department of Medicine, Karolinska Institute, Stockholm SE-171 77, Sweden
| | - Ralph Knöll
- Department of Medicine, Karolinska Institute, Stockholm SE-171 77, Sweden.,AstraZeneca, R&D, Innovative Medicines & Early Development, Cardiovascular, Renal and Metabolic Diseases (CVRM), Pepparedsleden 1, SE-431 83 Mölndal, Sweden
| | - Jack-Yves Deschamps
- Emergency and Critical Care Unit, ONIRIS, School of Veterinary Medicine, La Chantrerie, 44307 Nantes Cedex 03, France
| | | | - Isabelle Richard
- Généthon INSERM, U951, INTEGRARE Research Unit, Evry F-91002, France.
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41
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Abstract
Muscle stiffness, muscle elasticity and explosive strength are the main components of athletes' performance and they show a sex-based as well as ethnicity variation. Muscle stiffness is thought to be one of the risk factors associated with sports injuries and is less common in females than in males. These observations may be explained by circulating levels of sex hormones and their specific receptors. It has been shown that higher levels of estrogen are associated with lower muscle stiffness responsible for suppression of collagen synthesis. It is thought that these properties, at least in part, depend on genetic factors. Particularly, the gene encoding estrogen receptor 1 (ESR1) is one of the candidates that may be associated with muscle stiffness. Muscle elasticity increases with aging and there is evidence suggesting that titin (encoded by the TTN gene), a protein that is expressed in cardiac and skeletal muscles, is one of the factors responsible for elastic properties of the muscles. Mutations in the TTN gene result in some types of muscular dystrophy or cardiomyopathy. In this context, TTN may be regarded as a promising candidate for studying the elastic properties of muscles in athletes. The physiological background of explosive strength depends not only on the muscle architecture and muscle fiber composition, but also on the central nervous system and functionality of neuromuscular units. These properties are, at least partly, genetically determined. In this context, the ACTN3 gene code for α-actinin 3 has been widely researched.
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42
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Wang Y, Li D, Lu J, Chen L, Zhang S, Qi W, Li W, Xu H. Long noncoding RNA TTN-AS1 facilitates tumorigenesis and metastasis by maintaining TTN expression in skin cutaneous melanoma. Cell Death Dis 2020; 11:664. [PMID: 32820147 PMCID: PMC7441063 DOI: 10.1038/s41419-020-02895-y] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Revised: 08/01/2020] [Accepted: 08/03/2020] [Indexed: 01/23/2023]
Abstract
The antisense transcript, emanating from the opposite strand to a protein-coding or sense strand, has been reported to have critical roles in gene regulation. The perturbation of an antisense RNA can alter the expression of sense messenger RNAs. In this study, a long noncoding RNA TTN-AS1 (lncRNA-TTN-AS1), which is transcribed in the opposite direction of the human titin (TTN) gene, has been identified and explored in skin cutaneous melanoma (SKCM). We found that the expression of TTN and lncRNA-TTN-AS1 had a significantly positive correlation in SKCM cells. Functionally, ectopic expression of TTN and lncRNA-TTN-AS1 promoted SKCM tumorigenesis and metastasis both in vitro and in vivo. Moreover, knockdown of TTN partially abrogated lncRNA-TTN-AS1 induced SKCM tumorigenesis. Mechanistically, hypomethylation of transcription initiation site was responsible for lncRNA-TTN-AS1 high expression levels. LncRNA-TTN-AS1 facilitated SKCM progression by promoting TTN expression at both transcriptional and posttranscriptional levels. As detailed, lncRNA-TTN-AS1 had a significant effect on the increase of TTN promoter activity. Besides, lncRNA-TTN-AS1 also induced the accumulation of TTN in cytoplasm by increasing the stability of TTN mRNA. Clinically, we found that high TTN and lncRNA-TTN-AS1 expression were positively correlated with poor overall survival of SKCM patients, and may be considered as novel biomarkers and drug targets for SKCM patients.
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Affiliation(s)
- Ying Wang
- The Engineering Research Center of Synthetic Peptide Drug Discovery and Evaluation of Jiangsu Province, China Pharmaceutical University, Nanjing, 210009, China.,State Key Laboratory of Natural Medicines, Ministry of Education, China Pharmaceutical University, Nanjing, 210009, China
| | - Dongping Li
- The Engineering Research Center of Synthetic Peptide Drug Discovery and Evaluation of Jiangsu Province, China Pharmaceutical University, Nanjing, 210009, China.,State Key Laboratory of Natural Medicines, Ministry of Education, China Pharmaceutical University, Nanjing, 210009, China
| | - Jiqiang Lu
- The Engineering Research Center of Synthetic Peptide Drug Discovery and Evaluation of Jiangsu Province, China Pharmaceutical University, Nanjing, 210009, China.,State Key Laboratory of Natural Medicines, Ministry of Education, China Pharmaceutical University, Nanjing, 210009, China
| | - Lin Chen
- The Engineering Research Center of Synthetic Peptide Drug Discovery and Evaluation of Jiangsu Province, China Pharmaceutical University, Nanjing, 210009, China.,State Key Laboratory of Natural Medicines, Ministry of Education, China Pharmaceutical University, Nanjing, 210009, China
| | - Shengnan Zhang
- The Engineering Research Center of Synthetic Peptide Drug Discovery and Evaluation of Jiangsu Province, China Pharmaceutical University, Nanjing, 210009, China.,State Key Laboratory of Natural Medicines, Ministry of Education, China Pharmaceutical University, Nanjing, 210009, China
| | - Weiyan Qi
- The Engineering Research Center of Synthetic Peptide Drug Discovery and Evaluation of Jiangsu Province, China Pharmaceutical University, Nanjing, 210009, China.,State Key Laboratory of Natural Medicines, Ministry of Education, China Pharmaceutical University, Nanjing, 210009, China
| | - Weiguang Li
- The Engineering Research Center of Synthetic Peptide Drug Discovery and Evaluation of Jiangsu Province, China Pharmaceutical University, Nanjing, 210009, China.,State Key Laboratory of Natural Medicines, Ministry of Education, China Pharmaceutical University, Nanjing, 210009, China
| | - Hanmei Xu
- The Engineering Research Center of Synthetic Peptide Drug Discovery and Evaluation of Jiangsu Province, China Pharmaceutical University, Nanjing, 210009, China. .,State Key Laboratory of Natural Medicines, Ministry of Education, China Pharmaceutical University, Nanjing, 210009, China.
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43
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Fochi S, Lorenzi P, Galasso M, Stefani C, Trabetti E, Zipeto D, Romanelli MG. The Emerging Role of the RBM20 and PTBP1 Ribonucleoproteins in Heart Development and Cardiovascular Diseases. Genes (Basel) 2020; 11:genes11040402. [PMID: 32276354 PMCID: PMC7230170 DOI: 10.3390/genes11040402] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Revised: 04/04/2020] [Accepted: 04/06/2020] [Indexed: 12/17/2022] Open
Abstract
Alternative splicing is a regulatory mechanism essential for cell differentiation and tissue organization. More than 90% of human genes are regulated by alternative splicing events, which participate in cell fate determination. The general mechanisms of splicing events are well known, whereas only recently have deep-sequencing, high throughput analyses and animal models provided novel information on the network of functionally coordinated, tissue-specific, alternatively spliced exons. Heart development and cardiac tissue differentiation require thoroughly regulated splicing events. The ribonucleoprotein RBM20 is a key regulator of the alternative splicing events required for functional and structural heart properties, such as the expression of TTN isoforms. Recently, the polypyrimidine tract-binding protein PTBP1 has been demonstrated to participate with RBM20 in regulating splicing events. In this review, we summarize the updated knowledge relative to RBM20 and PTBP1 structure and molecular function; their role in alternative splicing mechanisms involved in the heart development and function; RBM20 mutations associated with idiopathic dilated cardiovascular disease (DCM); and the consequences of RBM20-altered expression or dysfunction. Furthermore, we discuss the possible application of targeting RBM20 in new approaches in heart therapies.
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44
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Blair CA, Pruitt BL. Mechanobiology Assays with Applications in Cardiomyocyte Biology and Cardiotoxicity. Adv Healthc Mater 2020; 9:e1901656. [PMID: 32270928 PMCID: PMC7480481 DOI: 10.1002/adhm.201901656] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Revised: 01/31/2020] [Accepted: 02/03/2020] [Indexed: 12/19/2022]
Abstract
Cardiomyocytes are the motor units that drive the contraction and relaxation of the heart. Traditionally, testing of drugs for cardiotoxic effects has relied on primary cardiomyocytes from animal models and focused on short-term, electrophysiological, and arrhythmogenic effects. However, primary cardiomyocytes present challenges arising from their limited viability in culture, and tissue from animal models suffers from a mismatch in their physiology to that of human heart muscle. Human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) can address these challenges. They also offer the potential to study not only electrophysiological effects but also changes in cardiomyocyte contractile and mechanical function in response to cardiotoxic drugs. With growing recognition of the long-term cardiotoxic effects of some drugs on subcellular structure and function, there is increasing interest in using hiPSC-CMs for in vitro cardiotoxicity studies. This review provides a brief overview of techniques that can be used to quantify changes in the active force that cardiomyocytes generate and variations in their inherent stiffness in response to cardiotoxic drugs. It concludes by discussing the application of these tools in understanding how cardiotoxic drugs directly impact the mechanobiology of cardiomyocytes and how cardiomyocytes sense and respond to mechanical load at the cellular level.
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Affiliation(s)
- Cheavar A. Blair
- Department of mechanical Engineering, University of California Santa Barbara, Santa Barbara, CA, USA
- Biomolecular Science and Engineering, University of California Santa Barbara, Santa Barbara, CA, USA
| | - Beth L. Pruitt
- Department of mechanical Engineering, University of California Santa Barbara, Santa Barbara, CA, USA
- Biomolecular Science and Engineering, University of California Santa Barbara, Santa Barbara, CA, USA
- Molecular, Cellular and Developmental Biology, University of California Santa Barbara, Santa Barbara, CA, USA
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45
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Ward SR, Winters TM, O'Connor SM, Lieber RL. Non-linear Scaling of Passive Mechanical Properties in Fibers, Bundles, Fascicles and Whole Rabbit Muscles. Front Physiol 2020; 11:211. [PMID: 32265730 PMCID: PMC7098999 DOI: 10.3389/fphys.2020.00211] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Accepted: 02/24/2020] [Indexed: 01/26/2023] Open
Abstract
Defining variations in skeletal muscle passive mechanical properties at different size scales ranging from single muscle fibers to whole muscles is required in order to understand passive muscle function. It is also of interest from a muscle structural point-of-view to identify the source(s) of passive tension that function at each scale. Thus, we measured passive mechanical properties of single fibers, fiber bundles, fascicles, and whole muscles in three architecturally diverse muscles from New Zealand White rabbits (n = 6) subjected to linear deformation. Passive modulus was quantified at sarcomere lengths across the muscle’s anatomical range. Titin molecular mass and collagen content were also quantified at each size scale, and whole muscle architectural properties were measured. Passive modulus increased non-linearly from fiber to whole muscle for all three muscles emphasizing extracellular sources of passive tension (p < 0.001), and was different among muscles (p < 0.001), with significant muscle by size-scale interaction, indicating quantitatively different scaling for each muscle (p < 0.001). These findings provide insight into the structural basis of passive tension and suggest that the extracellular matrix (ECM) is the dominant contributor to whole muscle and fascicle passive tension. They also demonstrate that caution should be used when inferring whole muscle properties from reduced muscle size preparations such as muscle biopsies.
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Affiliation(s)
- Samuel R Ward
- Department of Bioengineering, University of California, San Diego, San Diego, CA, United States.,Department of Orthopaedic Surgery, University of California, San Diego, San Diego, CA, United States.,Department of Radiology, University of California, San Diego, San Diego, CA, United States
| | - Taylor M Winters
- Department of Bioengineering, University of California, San Diego, San Diego, CA, United States
| | - Shawn M O'Connor
- School of Exercise and Nutritional Sciences, San Diego State University, San Diego, CA, United States
| | - Richard L Lieber
- Department of Bioengineering, University of California, San Diego, San Diego, CA, United States.,Department of Orthopaedic Surgery, University of California, San Diego, San Diego, CA, United States.,Veteran's Administration San Diego Healthcare System, San Diego, CA, United States.,Shirley Ryan AbilityLab, Northwestern University, Chicago, IL, United States
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Lanzicher T, Zhou T, Saripalli C, Keschrumrus V, Smith III JE, Mayans O, Sbaizero O, Granzier H. Single-Molecule Force Spectroscopy on the N2A Element of Titin: Effects of Phosphorylation and CARP. Front Physiol 2020; 11:173. [PMID: 32256378 PMCID: PMC7093598 DOI: 10.3389/fphys.2020.00173] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2019] [Accepted: 02/13/2020] [Indexed: 01/08/2023] Open
Abstract
Titin is a large filamentous protein that forms a sarcomeric myofilament with a molecular spring region that develops force in stretched sarcomeres. The molecular spring has a complex make-up that includes the N2A element. This element largely consists of a 104-residue unique sequence (N2A-Us) flanked by immunoglobulin domains (I80 and I81). The N2A element is of interest because it assembles a signalosome with CARP (Cardiac Ankyrin Repeat Protein) as an important component; CARP both interacts with the N2A-Us and I81 and is highly upregulated in response to mechanical stress. The mechanical properties of the N2A element were studied using single-molecule force spectroscopy, including how these properties are affected by CARP and phosphorylation. Three protein constructs were made that consisted of 0, 1, or 2 N2A-Us elements with flanking I80 and I81 domains and with specific handles at their ends for study by atomic force microscopy (AFM). The N2A-Us behaved as an entropic spring with a persistence length (Lp) of ∼0.35 nm and contour length (Lc) of ∼39 nm. CARP increased the Lp of the N2A-Us and the unfolding force of the Ig domains; force clamp experiments showed that CARP reduced the Ig domain unfolding kinetics. These findings suggest that CARP might function as a molecular chaperone that protects I81 from unfolding when mechanical stress is high. The N2A-Us was found to be a PKA substrate, and phosphorylation was blocked by CARP. Mass spectrometry revealed a PKA phosphosite (Ser-9895 in NP_001254479.2) located at the border between the N2A-Us and I81. AFM studies showed that phosphorylation affected neither the Lp of the N2A-Us nor the Ig domain unfolding force (Funfold). Simulating the force-sarcomere length relation of a single titin molecule containing all spring elements showed that the compliance of the N2A-Us only slightly reduces passive force (1.4%) with an additional small reduction by CARP (0.3%). Thus, it is improbable that the compliance of the N2A element has a mechanical function per se. Instead, it is likely that this compliance has local effects on binding of signaling molecules and that it contributes thereby to strain- and phosphorylation- dependent mechano-signaling.
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Affiliation(s)
- Thomas Lanzicher
- Department of Cellular & Molecular Medicine, The University of Arizona, Tucson, AZ, United States
- Department of Engineering and Architecture, University of Trieste, Trieste, Italy
| | - Tiankun Zhou
- Department of Biology, University of Konstanz, Konstanz, Germany
| | - Chandra Saripalli
- Department of Cellular & Molecular Medicine, The University of Arizona, Tucson, AZ, United States
| | - Vic Keschrumrus
- Department of Cellular & Molecular Medicine, The University of Arizona, Tucson, AZ, United States
| | - John E. Smith III
- Department of Cellular & Molecular Medicine, The University of Arizona, Tucson, AZ, United States
| | - Olga Mayans
- Department of Biology, University of Konstanz, Konstanz, Germany
| | - Orfeo Sbaizero
- Department of Engineering and Architecture, University of Trieste, Trieste, Italy
| | - Henk Granzier
- Department of Cellular & Molecular Medicine, The University of Arizona, Tucson, AZ, United States
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Chung CS, Hiske MA, Chadha A, Mueller PJ. Compliant Titin Isoform Content Is Reduced in Left Ventricles of Sedentary Versus Active Rats. Front Physiol 2020; 11:15. [PMID: 32116740 PMCID: PMC7025574 DOI: 10.3389/fphys.2020.00015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Accepted: 01/13/2020] [Indexed: 11/30/2022] Open
Abstract
A sedentary lifestyle is associated with increased cardiovascular risk factors and reduced cardiac compliance when compared to a lifestyle that includes exercise training. Exercise training increases cardiac compliance in humans, but the mechanisms underlying this improvement are unknown. A major determinant of cardiac compliance is the compliance of the giant elastic protein titin. Experimentally reducing titin compliance in animal models reduces exercise tolerance, but it is not known whether sedentary versus chronic exercise conditions cause differences in titin isoform content. We hypothesized that sedentary conditions would be associated with a reduction in the content of the longer, more compliant N2BA isoform relative to the stiffer N2B isoform (yielding a reduced N2BA:N2B ratio) compared to age-matched exercising controls. We obtained left ventricles from 16-week old rats housed for 12 weeks in standard (sedentary) or voluntary running wheel (exercised) housing. The N2BA:N2B ratio was decreased in the hearts of sedentary versus active rats (p = 0.041). Gene expression of a titin mRNA splicing factor, RNA Binding Motif 20 protein (RBM20), correlated negatively with N2BA:N2B ratios (p = 0.006, r = -0.449), but was not different between groups, suggesting that RBM20 may be regulated post-transcriptionally. Total phosphorylation of cardiac titin was not different between the active and sedentary groups. This study is the first to demonstrate that sedentary rats exhibit reduced cardiac titin N2BA:N2B isoform ratios, which implies reduced cardiac compliance. These data suggest that a lack of exercise (running wheel) reduces cardiac compliance and that exercise itself increases cardiac compliance.
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48
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Bryen SJ, Ewans LJ, Pinner J, MacLennan SC, Donkervoort S, Castro D, Töpf A, O'Grady G, Cummings B, Chao KR, Weisburd B, Francioli L, Faiz F, Bournazos AM, Hu Y, Grosmann C, Malicki DM, Doyle H, Witting N, Vissing J, Claeys KG, Urankar K, Beleza-Meireles A, Baptista J, Ellard S, Savarese M, Johari M, Vihola A, Udd B, Majumdar A, Straub V, Bönnemann CG, MacArthur DG, Davis MR, Cooper ST. Recurrent TTN metatranscript-only c.39974-11T>G splice variant associated with autosomal recessive arthrogryposis multiplex congenita and myopathy. Hum Mutat 2019; 41:403-411. [PMID: 31660661 DOI: 10.1002/humu.23938] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Revised: 10/01/2019] [Accepted: 10/24/2019] [Indexed: 12/12/2022]
Abstract
We present eight families with arthrogryposis multiplex congenita and myopathy bearing a TTN intron 213 extended splice-site variant (NM_001267550.1:c.39974-11T>G), inherited in trans with a second pathogenic TTN variant. Muscle-derived RNA studies of three individuals confirmed mis-splicing induced by the c.39974-11T>G variant; in-frame exon 214 skipping or use of a cryptic 3' splice-site effecting a frameshift. Confounding interpretation of pathogenicity is the absence of exons 213-217 within the described skeletal muscle TTN N2A isoform. However, RNA-sequencing from 365 adult human gastrocnemius samples revealed that 56% specimens predominantly include exons 213-217 in TTN transcripts (inclusion rate ≥66%). Further, RNA-sequencing of five fetal muscle samples confirmed that 4/5 specimens predominantly include exons 213-217 (fifth sample inclusion rate 57%). Contractures improved significantly with age for four individuals, which may be linked to decreased expression of pathogenic fetal transcripts. Our study extends emerging evidence supporting a vital developmental role for TTN isoforms containing metatranscript-only exons.
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Affiliation(s)
- Samantha J Bryen
- Kids Neuroscience Centre, Kids Research, Children's Hospital at Westmead, Westmead, New South Wales, Australia.,Discipline of Child and Adolescent Health, The University of Sydney Children's Hospital Westmead Clinical School, Westmead, New South Wales, Australia
| | - Lisa J Ewans
- Department of Medical Genomics, Royal Prince Alfred Hospital, Camperdown, New South Wales, Australia.,Central Clinical School, University of Sydney, Sydney, New South Wales, Australia
| | - Jason Pinner
- Department of Medical Genomics, Royal Prince Alfred Hospital, Camperdown, New South Wales, Australia.,Centre for Clinical Genetics, Sydney Children's Hospital, Randwick, NSW, 2031, Australia
| | - Suzanna C MacLennan
- Neurology Department, Women's and Children's Hospital, North Adelaide, South Australia, Australia.,School of Paediatrics and Reproductive Health, University of Adelaide, Adelaide, South Australia, Australia
| | - Sandra Donkervoort
- Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland
| | - Diana Castro
- Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Ana Töpf
- John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Gina O'Grady
- Kids Neuroscience Centre, Kids Research, Children's Hospital at Westmead, Westmead, New South Wales, Australia.,Discipline of Child and Adolescent Health, The University of Sydney Children's Hospital Westmead Clinical School, Westmead, New South Wales, Australia
| | - Beryl Cummings
- Analytic and Translational Genetics Unit, Massachusetts General Hospital, Boston, Massachusetts.,Center for Mendelian Genomics, Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, Massachusetts.,Program in Medical and Population Genetics, Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, Massachusetts
| | - Katherine R Chao
- Analytic and Translational Genetics Unit, Massachusetts General Hospital, Boston, Massachusetts.,Center for Mendelian Genomics, Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, Massachusetts.,Program in Medical and Population Genetics, Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, Massachusetts
| | - Ben Weisburd
- Analytic and Translational Genetics Unit, Massachusetts General Hospital, Boston, Massachusetts.,Center for Mendelian Genomics, Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, Massachusetts.,Program in Medical and Population Genetics, Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, Massachusetts
| | - Laurent Francioli
- Analytic and Translational Genetics Unit, Massachusetts General Hospital, Boston, Massachusetts.,Center for Mendelian Genomics, Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, Massachusetts.,Program in Medical and Population Genetics, Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, Massachusetts
| | - Fathimath Faiz
- Department of Diagnostic Genomics, PathWest Laboratory Medicine, Nedlands, WA, Australia
| | - Adam M Bournazos
- Kids Neuroscience Centre, Kids Research, Children's Hospital at Westmead, Westmead, New South Wales, Australia.,Discipline of Child and Adolescent Health, The University of Sydney Children's Hospital Westmead Clinical School, Westmead, New South Wales, Australia
| | - Ying Hu
- Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland
| | - Carla Grosmann
- Department of Neurology, Rady Children's Hospital University of California San Diego, San Diego, California
| | - Denise M Malicki
- Department of Pathology, Rady Children's Hospital University of California San Diego, San Diego, California
| | - Helen Doyle
- Department of Histopathology, The Children's Hospital at Westmead, Sydney Children's Hospital Network, Westmead, NSW, Australia
| | - Nanna Witting
- Copenhagen Neuromuscular Center, Department of Neurology, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - John Vissing
- Copenhagen Neuromuscular Center, Department of Neurology, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Kristl G Claeys
- Department of Neurology, University Hospitals Leuven, Leuven, Belgium.,Laboratory for Muscle Diseases and Neuropathies, Department of Neurosciences, Experimental Neurology, KU Leuven-University of Leuven, Leuven, Belgium
| | - Kathryn Urankar
- Department of Neuropathology, Southmead Hospital, University Hospitals Bristol NHS Foundation Trust, Bristol, United Kingdom
| | - Ana Beleza-Meireles
- Clinical Genetics, Bristol Royal Hospital For Children, University Hospitals Bristol NHS Foundation Trust, Bristol, United Kingdom
| | - Julia Baptista
- Molecular Genetics Department, Royal Devon and Exeter NHS Foundation Trust, Exeter, United Kingdom.,Institute of Biomedical and Clinical Science, University of Exeter Medical School University of Exeter, Exeter, United Kingdom
| | - Sian Ellard
- Molecular Genetics Department, Royal Devon and Exeter NHS Foundation Trust, Exeter, United Kingdom.,Institute of Biomedical and Clinical Science, University of Exeter Medical School University of Exeter, Exeter, United Kingdom
| | - Marco Savarese
- Folkhälsan Research Center, Medicum, University of Helsinki, Haartmaninkatu 8, Helsinki, 00290, Finland
| | - Mridul Johari
- Folkhälsan Research Center, Medicum, University of Helsinki, Haartmaninkatu 8, Helsinki, 00290, Finland
| | - Anna Vihola
- Folkhälsan Research Center, Medicum, University of Helsinki, Haartmaninkatu 8, Helsinki, 00290, Finland
| | - Bjarne Udd
- Folkhälsan Research Center, Medicum, University of Helsinki, Haartmaninkatu 8, Helsinki, 00290, Finland.,Tampere Neuromuscular Center, Tampere University Hospital, Teiskontie 35, Tampere, 33520, Finland
| | - Anirban Majumdar
- Paediatric Neurology, Bristol Royal Hospital For Children, University Hospitals Bristol NHS Foundation Trust, Bristol, United Kingdom
| | - Volker Straub
- John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Carsten G Bönnemann
- Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland
| | - Daniel G MacArthur
- Analytic and Translational Genetics Unit, Massachusetts General Hospital, Boston, Massachusetts.,Center for Mendelian Genomics, Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, Massachusetts.,Program in Medical and Population Genetics, Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, Massachusetts
| | - Mark R Davis
- Department of Diagnostic Genomics, PathWest Laboratory Medicine, Nedlands, WA, Australia
| | - Sandra T Cooper
- Kids Neuroscience Centre, Kids Research, Children's Hospital at Westmead, Westmead, New South Wales, Australia.,Discipline of Child and Adolescent Health, The University of Sydney Children's Hospital Westmead Clinical School, Westmead, New South Wales, Australia.,Functional Neuromics, The Children's Medical Research Institute, Westmead, New South Wales, Australia
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49
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Tharp CA, Haywood ME, Sbaizero O, Taylor MRG, Mestroni L. The Giant Protein Titin's Role in Cardiomyopathy: Genetic, Transcriptional, and Post-translational Modifications of TTN and Their Contribution to Cardiac Disease. Front Physiol 2019; 10:1436. [PMID: 31849696 PMCID: PMC6892752 DOI: 10.3389/fphys.2019.01436] [Citation(s) in RCA: 65] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Accepted: 11/07/2019] [Indexed: 02/06/2023] Open
Abstract
Dilated cardiomyopathy (DCM) is a leading cause of heart failure, sudden cardiac death and heart transplant. DCM is inherited in approximately 50% of cases, in which the most frequent genetic defects are truncation variants of the titin gene (TTNtv). TTN encodes titin, which is the largest protein in the body and is an essential component of the sarcomere. Titin serves as a biological spring, spanning half of the sarcomere and connecting the Z-disk to the M-line, with scaffold and signaling functions. Truncations of titin are believed to lead to either haploinsufficiency and loss-of-function, or to a “poison peptide” effect. However, other titin mechanisms are postulated to influence cardiac function including post-translational modifications, in particular changes in titin phosphorylation that alters the stiffness of the protein, and diversity of alternative splicing that generates different titin isoforms. In this article, we review the role of TTN mutations in development of DCM, how differential expression of titin isoforms relate to DCM pathophysiology, and discuss how post-translational modifications of titin can affect cardiomyocyte function. Current research efforts aim to elucidate the contribution of titin to myofibril assembly, stability, and signal transduction, and how mutant titin leads to cardiac dysfunction and human disease. Future research will need to translate this knowledge toward novel therapeutic approaches that can modulate titin transcriptional and post-translational defects to treat DCM and heart failure.
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Affiliation(s)
- Charles A Tharp
- Adult Medical Genetics Program and Cardiovascular Institute, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - Mary E Haywood
- Adult Medical Genetics Program and Cardiovascular Institute, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - Orfeo Sbaizero
- Department of Engineering and Architecture, University of Trieste, Trieste, Italy
| | - Matthew R G Taylor
- Adult Medical Genetics Program and Cardiovascular Institute, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - Luisa Mestroni
- Adult Medical Genetics Program and Cardiovascular Institute, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
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50
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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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