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Strom J, Bull M, Gohlke J, Saripalli C, Methawasin M, Gotthardt M, Granzier H. Titin's cardiac-specific N2B element is critical to mechanotransduction during volume overload of the heart. J Mol Cell Cardiol 2024; 191:40-49. [PMID: 38604403 PMCID: PMC11229416 DOI: 10.1016/j.yjmcc.2024.04.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Revised: 03/09/2024] [Accepted: 04/08/2024] [Indexed: 04/13/2024]
Abstract
The heart has the ability to detect and respond to changes in mechanical load through a process called mechanotransduction. In this study, we focused on investigating the role of the cardiac-specific N2B element within the spring region of titin, which has been proposed to function as a mechanosensor. To assess its significance, we conducted experiments using N2B knockout (KO) mice and wildtype (WT) mice, subjecting them to three different conditions: 1) cardiac pressure overload induced by transverse aortic constriction (TAC), 2) volume overload caused by aortocaval fistula (ACF), and 3) exercise-induced hypertrophy through swimming. Under conditions of pressure overload (TAC), both genotypes exhibited similar hypertrophic responses. In contrast, WT mice displayed robust left ventricular hypertrophy after one week of volume overload (ACF), while the KO mice failed to undergo hypertrophy and experienced a high mortality rate. Similarly, swim exercise-induced hypertrophy was significantly reduced in the KO mice. RNA-Seq analysis revealed an abnormal β-adrenergic response to volume overload in the KO mice, as well as a diminished response to isoproterenol-induced hypertrophy. Because it is known that the N2B element interacts with the four-and-a-half LIM domains 1 and 2 (FHL1 and FHL2) proteins, both of which have been associated with mechanotransduction, we evaluated these proteins. Interestingly, while volume-overload resulted in FHL1 protein expression levels that were comparable between KO and WT mice, FHL2 protein levels were reduced by over 90% in the KO mice compared to WT. This suggests that in response to volume overload, FHL2 might act as a signaling mediator between the N2B element and downstream signaling pathways. Overall, our study highlights the importance of the N2B element in mechanosensing during volume overload, both in physiological and pathological settings.
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Affiliation(s)
- Joshua Strom
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85721, United States of America; Sarver Molecular Cardiovascular Research Program, University of Arizona, Tucson, AZ 85721, United States of America
| | - Mathew Bull
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85721, United States of America; Sarver Molecular Cardiovascular Research Program, University of Arizona, Tucson, AZ 85721, United States of America
| | - Jochen Gohlke
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85721, United States of America; Sarver Molecular Cardiovascular Research Program, University of Arizona, Tucson, AZ 85721, United States of America
| | - Chandra Saripalli
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85721, United States of America; Sarver Molecular Cardiovascular Research Program, University of Arizona, Tucson, AZ 85721, United States of America
| | - Mei Methawasin
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85721, United States of America; Sarver Molecular Cardiovascular Research Program, University of Arizona, Tucson, AZ 85721, United States of America
| | - Michael Gotthardt
- Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany; Department of Cardiology, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Henk Granzier
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85721, United States of America.
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2
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Casarella S, Ferla F, Di Francesco D, Canciani E, Rizzi M, Boccafoschi F. Focal Adhesion's Role in Cardiomyocytes Function: From Cardiomyogenesis to Mechanotransduction. Cells 2024; 13:664. [PMID: 38667279 PMCID: PMC11049660 DOI: 10.3390/cells13080664] [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: 02/23/2024] [Revised: 04/03/2024] [Accepted: 04/08/2024] [Indexed: 04/28/2024] Open
Abstract
Mechanotransduction refers to the ability of cells to sense mechanical stimuli and convert them into biochemical signals. In this context, the key players are focal adhesions (FAs): multiprotein complexes that link intracellular actin bundles and the extracellular matrix (ECM). FAs are involved in cellular adhesion, growth, differentiation, gene expression, migration, communication, force transmission, and contractility. Focal adhesion signaling molecules, including Focal Adhesion Kinase (FAK), integrins, vinculin, and paxillin, also play pivotal roles in cardiomyogenesis, impacting cell proliferation and heart tube looping. In fact, cardiomyocytes sense ECM stiffness through integrins, modulating signaling pathways like PI3K/AKT and Wnt/β-catenin. Moreover, FAK/Src complex activation mediates cardiac hypertrophic growth and survival signaling in response to mechanical loads. This review provides an overview of the molecular and mechanical mechanisms underlying the crosstalk between FAs and cardiac differentiation, as well as the role of FA-mediated mechanotransduction in guiding cardiac muscle responses to mechanical stimuli.
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Affiliation(s)
- Simona Casarella
- Department of Health Sciences, University of Piemonte Orientale, 28100 Novara, Italy; (S.C.); (D.D.F.); (E.C.); (M.R.)
| | - Federica Ferla
- Department of Health Sciences, University of Piemonte Orientale, 28100 Novara, Italy; (S.C.); (D.D.F.); (E.C.); (M.R.)
| | - Dalila Di Francesco
- Department of Health Sciences, University of Piemonte Orientale, 28100 Novara, Italy; (S.C.); (D.D.F.); (E.C.); (M.R.)
- Laboratory for Biomaterials and Bioengineering, CRC-I, Department of Min-Met-Materials Engineering, University Hospital Research Center, Regenerative Medicine, Laval University, Quebec City, QC G1V 0A6, Canada
| | - Elena Canciani
- Department of Health Sciences, University of Piemonte Orientale, 28100 Novara, Italy; (S.C.); (D.D.F.); (E.C.); (M.R.)
| | - Manuela Rizzi
- Department of Health Sciences, University of Piemonte Orientale, 28100 Novara, Italy; (S.C.); (D.D.F.); (E.C.); (M.R.)
| | - Francesca Boccafoschi
- Department of Health Sciences, University of Piemonte Orientale, 28100 Novara, Italy; (S.C.); (D.D.F.); (E.C.); (M.R.)
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3
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Garg A, Lavine KJ, Greenberg MJ. Assessing Cardiac Contractility From Single Molecules to Whole Hearts. JACC Basic Transl Sci 2024; 9:414-439. [PMID: 38559627 PMCID: PMC10978360 DOI: 10.1016/j.jacbts.2023.07.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Revised: 07/14/2023] [Accepted: 07/14/2023] [Indexed: 04/04/2024]
Abstract
Fundamentally, the heart needs to generate sufficient force and power output to dynamically meet the needs of the body. Cardiomyocytes contain specialized structures referred to as sarcomeres that power and regulate contraction. Disruption of sarcomeric function or regulation impairs contractility and leads to cardiomyopathies and heart failure. Basic, translational, and clinical studies have adapted numerous methods to assess cardiac contraction in a variety of pathophysiological contexts. These tools measure aspects of cardiac contraction at different scales ranging from single molecules to whole organisms. Moreover, these studies have revealed new pathogenic mechanisms of heart disease leading to the development of novel therapies targeting contractility. In this review, the authors explore the breadth of tools available for studying cardiac contractile function across scales, discuss their strengths and limitations, highlight new insights into cardiac physiology and pathophysiology, and describe how these insights can be harnessed for therapeutic candidate development and translational.
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Affiliation(s)
- Ankit Garg
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri, USA
- Center for Cardiovascular Research, Division of Cardiology, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Kory J. Lavine
- Center for Cardiovascular Research, Division of Cardiology, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Michael J. Greenberg
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri, USA
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4
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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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5
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Gregorich ZR, Yanghai Z, Kamp TJ, Granzier H, Guo W. Mechanisms of RBM20 Cardiomyopathy: Insights From Model Systems. CIRCULATION. GENOMIC AND PRECISION MEDICINE 2024; 17:e004355. [PMID: 38288598 PMCID: PMC10923161 DOI: 10.1161/circgen.123.004355] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2024]
Abstract
RBM20 (RNA-binding motif protein 20) is a vertebrate- and muscle-specific RNA-binding protein that belongs to the serine-arginine-rich family of splicing factors. The RBM20 gene was first identified as a dilated cardiomyopathy-linked gene over a decade ago. Early studies in Rbm20 knockout rodents implicated disrupted splicing of RBM20 target genes as a causative mechanism. Clinical studies show that pathogenic variants in RBM20 are linked to aggressive dilated cardiomyopathy with early onset heart failure and high mortality. Subsequent studies employing pathogenic variant knock-in animal models revealed that variants in a specific portion of the arginine-serine-rich domain in RBM20 not only disrupt splicing but also hinder nucleocytoplasmic transport and lead to the formation of RBM20 biomolecular condensates in the sarcoplasm. Conversely, mice harboring a disease-associated variant in the RRM (RNA recognition motif) do not show evidence of adverse remodeling or exhibit sudden death despite disrupted splicing of RBM20 target genes. Thus, whether disrupted splicing, biomolecular condensates, or both contribute to dilated cardiomyopathy is under debate. Beyond this, additional questions remain, such as whether there is sexual dimorphism in the presentation of RBM20 cardiomyopathy. What are the clinical features of RBM20 cardiomyopathy and why do some individuals develop more severe disease than others? In this review, we summarize the reported observations and discuss potential mechanisms of RBM20 cardiomyopathy derived from studies employing in vivo animal models and in vitro human-induced pluripotent stem cell-derived cardiomyocytes. Potential therapeutic strategies to treat RBM20 cardiomyopathy are also discussed.
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Affiliation(s)
- Zachery R. Gregorich
- Department of Animal and Dairy Sciences, University of Wisconsin-Madison, Madison, WI
| | - Zhang Yanghai
- Department of Animal and Dairy Sciences, University of Wisconsin-Madison, Madison, WI
| | - Timothy J. Kamp
- Cellular and Molecular Arrhythmia Research Program, University of Wisconsin-Madison, Madison, WI
- Department of Medicine, University of Wisconsin-Madison, Madison, WI
- Cardiovascular Research Center, University of Wisconsin-Madison, Madison, WI
| | - Henk Granzier
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ
| | - Wei Guo
- Department of Animal and Dairy Sciences, University of Wisconsin-Madison, Madison, WI
- Cardiovascular Research Center, University of Wisconsin-Madison, Madison, WI
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6
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Neininger-Castro AC, Hayes JB, Sanchez ZC, Taneja N, Fenix AM, Moparthi S, Vassilopoulos S, Burnette DT. Independent regulation of Z-lines and M-lines during sarcomere assembly in cardiac myocytes revealed by the automatic image analysis software sarcApp. eLife 2023; 12:RP87065. [PMID: 37921850 PMCID: PMC10624428 DOI: 10.7554/elife.87065] [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] [Indexed: 11/04/2023] Open
Abstract
Sarcomeres are the basic contractile units within cardiac myocytes, and the collective shortening of sarcomeres aligned along myofibrils generates the force driving the heartbeat. The alignment of the individual sarcomeres is important for proper force generation, and misaligned sarcomeres are associated with diseases, including cardiomyopathies and COVID-19. The actin bundling protein, α-actinin-2, localizes to the 'Z-Bodies" of sarcomere precursors and the 'Z-Lines' of sarcomeres, and has been used previously to assess sarcomere assembly and maintenance. Previous measurements of α-actinin-2 organization have been largely accomplished manually, which is time-consuming and has hampered research progress. Here, we introduce sarcApp, an image analysis tool that quantifies several components of the cardiac sarcomere and their alignment in muscle cells and tissue. We first developed sarcApp to utilize deep learning-based segmentation and real space quantification to measure α-actinin-2 structures and determine the organization of both precursors and sarcomeres/myofibrils. We then expanded sarcApp to analyze 'M-Lines' using the localization of myomesin and a protein that connects the Z-Lines to the M-Line (titin). sarcApp produces 33 distinct measurements per cell and 24 per myofibril that allow for precise quantification of changes in sarcomeres, myofibrils, and their precursors. We validated this system with perturbations to sarcomere assembly. We found perturbations that affected Z-Lines and M-Lines differently, suggesting that they may be regulated independently during sarcomere assembly.
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Affiliation(s)
- Abigail C Neininger-Castro
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine Basic SciencesNashvilleUnited States
| | - James B Hayes
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine Basic SciencesNashvilleUnited States
| | - Zachary C Sanchez
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine Basic SciencesNashvilleUnited States
| | - Nilay Taneja
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine Basic SciencesNashvilleUnited States
| | - Aidan M Fenix
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine Basic SciencesNashvilleUnited States
| | - Satish Moparthi
- Sorbonne Université, INSERM, Institut de Myologie, Centre de Recherche en MyologieParisFrance
| | - Stéphane Vassilopoulos
- Sorbonne Université, INSERM, Institut de Myologie, Centre de Recherche en MyologieParisFrance
| | - Dylan Tyler Burnette
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine Basic SciencesNashvilleUnited States
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7
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Neininger-Castro AC, Hayes JB, Sanchez ZC, Taneja N, Fenix AM, Moparthi S, Vassilopoulos S, Burnette DT. Independent regulation of Z-lines and M-lines during sarcomere assembly in cardiac myocytes revealed by the automatic image analysis software sarcApp. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.11.523681. [PMID: 36711995 PMCID: PMC9882215 DOI: 10.1101/2023.01.11.523681] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Sarcomeres are the basic contractile units within cardiac myocytes, and the collective shortening of sarcomeres aligned along myofibrils generates the force driving the heartbeat. The alignment of the individual sarcomeres is important for proper force generation, and misaligned sarcomeres are associated with diseases including cardiomyopathies and COVID-19. The actin bundling protein, α-actinin-2, localizes to the "Z-Bodies" of sarcomere precursors and the "Z-Lines" of sarcomeres, and has been used previously to assess sarcomere assembly and maintenance. Previous measurements of α-actinin-2 organization have been largely accomplished manually, which is time-consuming and has hampered research progress. Here, we introduce sarcApp, an image analysis tool that quantifies several components of the cardiac sarcomere and their alignment in muscle cells and tissue. We first developed sarcApp to utilize deep learning-based segmentation and real space quantification to measure α-actinin-2 structures and determine the organization of both precursors and sarcomeres/myofibrils. We then expanded sarcApp to analyze "M-Lines" using the localization of myomesin and a protein that connects the Z-Lines to the M-Line (titin). sarcApp produces 33 distinct measurements per cell and 24 per myofibril that allow for precise quantification of changes in sarcomeres, myofibrils, and their precursors. We validated this system with perturbations to sarcomere assembly. We found perturbations that affected Z-Lines and M-Lines differently, suggesting that they may be regulated independently during sarcomere assembly.
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Affiliation(s)
- Abigail C. Neininger-Castro
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine Basic Sciences, Nashville, TN
| | - James B. Hayes
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine Basic Sciences, Nashville, TN
| | - Zachary C. Sanchez
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine Basic Sciences, Nashville, TN
| | - Nilay Taneja
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine Basic Sciences, Nashville, TN
| | - Aidan M. Fenix
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine Basic Sciences, Nashville, TN
| | - Satish Moparthi
- Sorbonne Université, INSERM, Institut de Myologie, Centre de Recherche en Myologie, Paris, France
| | - Stéphane Vassilopoulos
- Sorbonne Université, INSERM, Institut de Myologie, Centre de Recherche en Myologie, Paris, France
| | - Dylan T. Burnette
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine Basic Sciences, Nashville, TN
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8
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Titin activates myosin filaments in skeletal muscle by switching from an extensible spring to a mechanical rectifier. Proc Natl Acad Sci U S A 2023; 120:e2219346120. [PMID: 36812205 PMCID: PMC9992839 DOI: 10.1073/pnas.2219346120] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/24/2023] Open
Abstract
Titin is a molecular spring in parallel with myosin motors in each muscle half-sarcomere, responsible for passive force development at sarcomere length (SL) above the physiological range (>2.7 μm). The role of titin at physiological SL is unclear and is investigated here in single intact muscle cells of the frog (Rana esculenta), by combining half-sarcomere mechanics and synchrotron X-ray diffraction in the presence of 20 μM para-nitro-blebbistatin, which abolishes the activity of myosin motors and maintains them in the resting state even during activation of the cell by electrical stimulation. We show that, during cell activation at physiological SL, titin in the I-band switches from an SL-dependent extensible spring (OFF-state) to an SL-independent rectifier (ON-state) that allows free shortening while resisting stretch with an effective stiffness of ~3 pN nm-1 per half-thick filament. In this way, I-band titin efficiently transmits any load increase to the myosin filament in the A-band. Small-angle X-ray diffraction signals reveal that, with I-band titin ON, the periodic interactions of A-band titin with myosin motors alter their resting disposition in a load-dependent manner, biasing the azimuthal orientation of the motors toward actin. This work sets the stage for future investigations on scaffold and mechanosensing-based signaling functions of titin in health and disease.
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9
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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: 5] [Impact Index Per Article: 2.5] [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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10
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Prodanovic M, Geeves MA, Poggesi C, Regnier M, Mijailovich SM. Effect of Myosin Isoforms on Cardiac Muscle Twitch of Mice, Rats and Humans. Int J Mol Sci 2022; 23:1135. [PMID: 35163054 PMCID: PMC8835009 DOI: 10.3390/ijms23031135] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Revised: 01/16/2022] [Accepted: 01/18/2022] [Indexed: 02/04/2023] Open
Abstract
To understand how pathology-induced changes in contractile protein isoforms modulate cardiac muscle function, it is necessary to quantify the temporal-mechanical properties of contractions that occur under various conditions. Pathological responses are much easier to study in animal model systems than in humans, but extrapolation between species presents numerous challenges. Employing computational approaches can help elucidate relationships that are difficult to test experimentally by translating the observations from rats and mice, as model organisms, to the human heart. Here, we use the spatially explicit MUSICO platform to model twitch contractions from rodent and human trabeculae collected in a single laboratory. This approach allowed us to identify the variations in kinetic characteristics of α- and β-myosin isoforms across species and to quantify their effect on cardiac muscle contractile responses. The simulations showed how the twitch transient varied with the ratio of the two myosin isoforms. Particularly, the rate of tension rise was proportional to the fraction of α-myosin present, while the β-isoform dominated the rate of relaxation unless α-myosin was >50%. Moreover, both the myosin isoform and the Ca2+ transient contributed to the twitch tension transient, allowing two levels of regulation of twitch contraction.
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Affiliation(s)
- Momcilo Prodanovic
- Institute for Information Technologies, University of Kragujevac, 34000 Kragujevac, Serbia;
- Bioengineering Research and Development Center (BioIRC), 34000 Kragujevac, Serbia
- FilamenTech, Inc., Newtown, MA 02458, USA
| | - Michael A. Geeves
- Department of Biosciences, University of Kent, Canterbury CT2 7NJ, Kent, UK;
| | - Corrado Poggesi
- Department of Experimental & Clinical Medicine, University of Florence, 20134 Florence, Italy;
| | - Michael Regnier
- Department of Bioengineering, University of Washington, Seattle, WA 98105, USA;
| | - Srboljub M. Mijailovich
- FilamenTech, Inc., Newtown, MA 02458, USA
- Department of Biology, Illinois Institute of Technology, Chicago, IL 60616, USA
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11
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Cappelli K, Mecocci S, Capomaccio S, Beccati F, Palumbo AR, Tognoloni A, Pepe M, Chiaradia E. Circulating Transcriptional Profile Modulation in Response to Metabolic Unbalance Due to Long-Term Exercise in Equine Athletes: A Pilot Study. Genes (Basel) 2021; 12:genes12121965. [PMID: 34946914 PMCID: PMC8701225 DOI: 10.3390/genes12121965] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Revised: 12/06/2021] [Accepted: 12/06/2021] [Indexed: 11/26/2022] Open
Abstract
Physical exercise has been associated with the modulation of micro RNAs (miRNAs), actively released in body fluids and recognized as accurate biomarkers. The aim of this study was to measure serum miRNA profiles in 18 horses taking part in endurance competitions, which represents a good model to test metabolic responses to moderate intensity prolonged efforts. Serum levels of miRNAs of eight horses that were eliminated due to metabolic unbalance (Non Performer-NP) were compared to those of 10 horses that finished an endurance competition in excellent metabolic condition (Performer-P). Circulating miRNA (ci-miRNA) profiles in serum were analyzed through sequencing, and differential gene expression analysis was assessed comparing NP versus P groups. Target and pathway analysis revealed the up regulation of a set of miRNAs (of mir-211 mir-451, mir-106b, mir-15b, mir-101-1, mir-18a, mir-20a) involved in the modulation of myogenesis, cardiac and skeletal muscle remodeling, angiogenesis, ventricular contractility, and in the regulation of gene expression. Our preliminary data open new scenarios in the definition of metabolic adaptations to the establishment of efficient training programs and the validation of athletes’ elimination from competitions.
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Affiliation(s)
- Katia Cappelli
- Department of Veterinary Medicine, University of Perugia, 06126 Perugia, Italy; (K.C.); (S.M.); (F.B.); (A.R.P.); (A.T.); (M.P.); (E.C.)
- Sports Horse Research Center, University of Perugia, 06126 Perugia, Italy
| | - Samanta Mecocci
- Department of Veterinary Medicine, University of Perugia, 06126 Perugia, Italy; (K.C.); (S.M.); (F.B.); (A.R.P.); (A.T.); (M.P.); (E.C.)
| | - Stefano Capomaccio
- Department of Veterinary Medicine, University of Perugia, 06126 Perugia, Italy; (K.C.); (S.M.); (F.B.); (A.R.P.); (A.T.); (M.P.); (E.C.)
- Sports Horse Research Center, University of Perugia, 06126 Perugia, Italy
- Correspondence: ; Tel.: +39-0755857765
| | - Francesca Beccati
- Department of Veterinary Medicine, University of Perugia, 06126 Perugia, Italy; (K.C.); (S.M.); (F.B.); (A.R.P.); (A.T.); (M.P.); (E.C.)
- Sports Horse Research Center, University of Perugia, 06126 Perugia, Italy
| | - Andrea Rosario Palumbo
- Department of Veterinary Medicine, University of Perugia, 06126 Perugia, Italy; (K.C.); (S.M.); (F.B.); (A.R.P.); (A.T.); (M.P.); (E.C.)
| | - Alessia Tognoloni
- Department of Veterinary Medicine, University of Perugia, 06126 Perugia, Italy; (K.C.); (S.M.); (F.B.); (A.R.P.); (A.T.); (M.P.); (E.C.)
| | - Marco Pepe
- Department of Veterinary Medicine, University of Perugia, 06126 Perugia, Italy; (K.C.); (S.M.); (F.B.); (A.R.P.); (A.T.); (M.P.); (E.C.)
- Sports Horse Research Center, University of Perugia, 06126 Perugia, Italy
| | - Elisabetta Chiaradia
- Department of Veterinary Medicine, University of Perugia, 06126 Perugia, Italy; (K.C.); (S.M.); (F.B.); (A.R.P.); (A.T.); (M.P.); (E.C.)
- Sports Horse Research Center, University of Perugia, 06126 Perugia, Italy
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12
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Fomin A, Gärtner A, Cyganek L, Tiburcy M, Tuleta I, Wellers L, Folsche L, Hobbach AJ, von Frieling-Salewsky M, Unger A, Hucke A, Koser F, Kassner A, Sielemann K, Streckfuß-Bömeke K, Hasenfuss G, Goedel A, Laugwitz KL, Moretti A, Gummert JF, Dos Remedios CG, Reinecke H, Knöll R, van Heesch S, Hubner N, Zimmermann WH, Milting H, Linke WA. Truncated titin proteins and titin haploinsufficiency are targets for functional recovery in human cardiomyopathy due to TTN mutations. Sci Transl Med 2021; 13:eabd3079. [PMID: 34731013 DOI: 10.1126/scitranslmed.abd3079] [Citation(s) in RCA: 56] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
[Figure: see text].
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Affiliation(s)
- Andrey Fomin
- Clinic for Cardiology and Pneumology, University Medical Center, 37075 Göttingen, Germany.,German Centre for Cardiovascular Research, 10785 Berlin, partner site Göttingen, Germany
| | - Anna Gärtner
- Erich and Hanna Klessmann Institute, Heart and Diabetes Centre NRW, University Hospital of the Ruhr-University Bochum, 32545 Bad Oeynhausen, Germany
| | - Lukas Cyganek
- Clinic for Cardiology and Pneumology, University Medical Center, 37075 Göttingen, Germany.,German Centre for Cardiovascular Research, 10785 Berlin, partner site Göttingen, Germany.,Stem Cell Unit, University Medical Center, 37075 Göttingen, Germany.,Institute of Pharmacology and Toxicology, University Medical Center, 37075 Göttingen, Germany
| | - Malte Tiburcy
- German Centre for Cardiovascular Research, 10785 Berlin, partner site Göttingen, Germany.,Institute of Pharmacology and Toxicology, University Medical Center, 37075 Göttingen, Germany
| | - Izabela Tuleta
- Department of Cardiology I, Coronary, Peripheral Vascular Disease and Heart Failure, 48149 University Hospital Münster, Münster, Germany
| | - Luisa Wellers
- Institute of Physiology II, University of Münster, 48149 Münster, Germany
| | - Lina Folsche
- Institute of Physiology II, University of Münster, 48149 Münster, Germany
| | - Anastasia J Hobbach
- Department of Cardiology I, Coronary, Peripheral Vascular Disease and Heart Failure, 48149 University Hospital Münster, Münster, Germany
| | | | - Andreas Unger
- Institute of Physiology II, University of Münster, 48149 Münster, Germany
| | - Anna Hucke
- Institute of Physiology II, University of Münster, 48149 Münster, Germany
| | - Franziska Koser
- Institute of Physiology II, University of Münster, 48149 Münster, Germany
| | - Astrid Kassner
- Erich and Hanna Klessmann Institute, Heart and Diabetes Centre NRW, University Hospital of the Ruhr-University Bochum, 32545 Bad Oeynhausen, Germany
| | - Katharina Sielemann
- Erich and Hanna Klessmann Institute, Heart and Diabetes Centre NRW, University Hospital of the Ruhr-University Bochum, 32545 Bad Oeynhausen, Germany
| | - Katrin Streckfuß-Bömeke
- Clinic for Cardiology and Pneumology, University Medical Center, 37075 Göttingen, Germany.,German Centre for Cardiovascular Research, 10785 Berlin, partner site Göttingen, Germany
| | - Gerd Hasenfuss
- Clinic for Cardiology and Pneumology, University Medical Center, 37075 Göttingen, Germany.,German Centre for Cardiovascular Research, 10785 Berlin, partner site Göttingen, Germany
| | - Alexander Goedel
- First Medical Department, Cardiology, Technical University of Munich, 81675 Munich, Germany.,German Centre for Cardiovascular Research, 10785 Berlin, partner site Munich, Germany.,Department of Cell and Molecular Biology, Karolinska Institute, S-17177 Stockholm, Sweden
| | - Karl-Ludwig Laugwitz
- First Medical Department, Cardiology, Technical University of Munich, 81675 Munich, Germany.,German Centre for Cardiovascular Research, 10785 Berlin, partner site Munich, Germany.,Munich Heart Alliance, 80802 Munich, Germany
| | - Alessandra Moretti
- First Medical Department, Cardiology, Technical University of Munich, 81675 Munich, Germany.,German Centre for Cardiovascular Research, 10785 Berlin, partner site Munich, Germany.,Munich Heart Alliance, 80802 Munich, Germany
| | - Jan F Gummert
- Erich and Hanna Klessmann Institute, Heart and Diabetes Centre NRW, University Hospital of the Ruhr-University Bochum, 32545 Bad Oeynhausen, Germany.,Department of Cardio-Thoracic Surgery, Heart and Diabetes Centre NRW, University Hospital of the Ruhr-University Bochum, 32545 Bad Oeynhausen, Germany
| | | | - Holger Reinecke
- Department of Cardiology I, Coronary, Peripheral Vascular Disease and Heart Failure, 48149 University Hospital Münster, Münster, Germany
| | - Ralph Knöll
- Department of Medicine, Integrated Cardio Metabolic Centre (ICMC), Heart and Vascular Theme, Karolinska Institute, S-17177 Stockholm, Sweden.,Bioscience Cardiovascular, Research and Early Development, Cardiovascular, Renal and Metabolism (CVRM), BioPharmaceuticals R&D, AstraZeneca, 43183 Gothenburg, Sweden
| | - Sebastiaan van Heesch
- Cardiovascular and Metabolic Sciences, Max Delbrück Center for Molecular Medicine in the Helmholtz Association, 13125 Berlin, Germany.,German Centre for Cardiovascular Research, 10785 Berlin, partner site Berlin, Germany.,Princess Máxima Center for Pediatric Oncology, 3584 CT Utrecht, Netherlands
| | - Norbert Hubner
- Cardiovascular and Metabolic Sciences, Max Delbrück Center for Molecular Medicine in the Helmholtz Association, 13125 Berlin, Germany.,German Centre for Cardiovascular Research, 10785 Berlin, partner site Berlin, Germany.,Charité-Universitätsmedizin, 10117 Berlin, Germany.,Berlin Institute of Health, 10178 Berlin, Germany
| | - Wolfram H Zimmermann
- German Centre for Cardiovascular Research, 10785 Berlin, partner site Göttingen, Germany.,Institute of Pharmacology and Toxicology, University Medical Center, 37075 Göttingen, Germany.,Cluster of Excellence "Multiscale Bioimaging: From Molecular Machines to Networks of Excitable Cells," University of Göttingen, 37073 Göttingen, Germany
| | - Hendrik Milting
- Erich and Hanna Klessmann Institute, Heart and Diabetes Centre NRW, University Hospital of the Ruhr-University Bochum, 32545 Bad Oeynhausen, Germany
| | - Wolfgang A Linke
- Clinic for Cardiology and Pneumology, University Medical Center, 37075 Göttingen, Germany.,German Centre for Cardiovascular Research, 10785 Berlin, partner site Göttingen, Germany.,Institute of Physiology II, University of Münster, 48149 Münster, Germany
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13
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Kim KH, Pereira NL. Genetics of Cardiomyopathy: Clinical and Mechanistic Implications for Heart Failure. Korean Circ J 2021; 51:797-836. [PMID: 34327881 PMCID: PMC8484993 DOI: 10.4070/kcj.2021.0154] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Accepted: 06/14/2021] [Indexed: 11/11/2022] Open
Abstract
Genetic cardiomyopathies are an important cause of sudden cardiac death across all age groups. Genetic testing in heart failure clinics is useful for family screening and providing individual prognostic insight. Obtaining a family history of at least three generations, including the creation of a pedigree, is recommended for all patients with primary cardiomyopathy. Additionally, when appropriate, consultation with a genetic counsellor can aid in the success of a genetic evaluation. Clinical screening should be performed on all first-degree relatives of patients with genetic cardiomyopathy. Genetics has played an important role in the understanding of different cardiomyopathies, and the field of heart failure (HF) genetics is progressing rapidly. Much research has also focused on distinguishing markers of risk in patients with cardiomyopathy using genetic testing. While these efforts currently remain incomplete, new genomic technologies and analytical strategies provide promising opportunities to further explore the genetic architecture of cardiomyopathies, afford insight into the early manifestations of cardiomyopathy, and help define the molecular pathophysiological basis for cardiac remodeling. Cardiovascular physicians should be fully aware of the utility and potential pitfalls of incorporating genetic test results into pre-emptive treatment strategies for patients in the preliminary stages of HF. Future work will need to be directed towards elucidating the biological mechanisms of both rare and common gene variants and environmental determinants of plasticity in the genotype-phenotype relationship. This future research should aim to further our ability to identify, diagnose, and treat disorders that cause HF and sudden cardiac death in young patients, as well as prioritize improving our ability to stratify the risk for these patients prior to the onset of the more severe consequences of their disease.
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Affiliation(s)
- Kyung Hee Kim
- Division of Cardiology, Incheon Sejong General Hospital, Incheon, Korea.
| | - Naveen L Pereira
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN, USA.,Department of Clinical Genomics, Mayo Clinic, Rochester, MN, USA
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14
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The Combined Human Genotype of Truncating TTN and RBM20 Mutations Is Associated with Severe and Early Onset of Dilated Cardiomyopathy. Genes (Basel) 2021; 12:genes12060883. [PMID: 34201072 PMCID: PMC8228627 DOI: 10.3390/genes12060883] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Revised: 06/01/2021] [Accepted: 06/05/2021] [Indexed: 12/30/2022] Open
Abstract
A major cause of heart failure is cardiomyopathies, with dilated cardiomyopathy (DCM) as the most common form. Over 40 genes are linked to DCM, among them TTN and RBM20. Next Generation Sequencing in clinical DCM cohorts revealed truncating variants in TTN (TTNtv), accounting for up to 25% of familial DCM cases. Mutations in the cardiac splicing factor RNA binding motif protein 20 (RBM20) are also known to be associated with severe cardiomyopathies. TTN is one of the major RBM20 splicing targets. Most of the pathogenic RBM20 mutations are localized in the highly conserved arginine serine rich domain (RS), leading to a cytoplasmic mislocalization of mutant RBM20. Here, we present a patient with an early onset DCM carrying a combination of (likely) pathogenic TTN and RBM20 mutations. We show that the splicing of RBM20 target genes is affected in the mutation carrier. Furthermore, we reveal RBM20 haploinsufficiency presumably caused by the frameshift mutation in RBM20.
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15
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Zhang X, Zhu F, Tong Y, Liang F, Zhang X. Effect of Chronic and Acute Psychological Stress and Fluoxetine on Biomolecules of Heart. INT J PHARMACOL 2021. [DOI: 10.3923/ijp.2021.292.299] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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16
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Piroddi N, Pesce P, Scellini B, Manzini S, Ganzetti GS, Badi I, Menegollo M, Cora V, Tiso S, Cinquetti R, Monti L, Chiesa G, Bleyl SB, Busnelli M, Dellera F, Bruno D, Caicci F, Grimaldi A, Taramelli R, Manni L, Sacerdoti D, Tesi C, Poggesi C, Ausoni S, Acquati F, Campione M. Myocardial overexpression of ANKRD1 causes sinus venosus defects and progressive diastolic dysfunction. Cardiovasc Res 2021; 116:1458-1472. [PMID: 31688894 DOI: 10.1093/cvr/cvz291] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Revised: 09/26/2019] [Accepted: 10/30/2019] [Indexed: 12/11/2022] Open
Abstract
AIMS Increased Ankyrin Repeat Domain 1 (ANKRD1) levels linked to gain of function mutations have been associated to total anomalous pulmonary venous return and adult cardiomyopathy occurrence in humans. The link between increased ANKRD1 level and cardiac structural and functional disease is not understood. To get insight into this problem, we have generated a gain of function ANKRD1 mouse model by overexpressing ANKRD1 in the myocardium. METHODS AND RESULTS Ankrd1 is expressed non-homogeneously in the embryonic myocardium, with a dynamic nucleo-sarcomeric localization in developing cardiomyocytes. ANKRD1 transgenic mice present sinus venosus defect, which originates during development by impaired remodelling of early embryonic heart. Adult transgenic hearts develop diastolic dysfunction with preserved ejection fraction, which progressively evolves into heart failure, as shown histologically and haemodynamically. Transgenic cardiomyocyte structure, sarcomeric assembly, and stability are progressively impaired from embryonic to adult life. Postnatal transgenic myofibrils also present characteristic functional alterations: impaired compliance at neonatal stage and impaired lusitropism in adult hearts. Altogether, our combined analyses suggest that impaired embryonic remodelling and adult heart dysfunction in ANKRD1 transgenic mice present a common ground of initial cardiomyocyte defects, which are exacerbated postnatally. Molecular analysis showed transient activation of GATA4-Nkx2.5 transcription in early transgenic embryos and subsequent dynamic transcriptional modulation within titin gene. CONCLUSIONS ANKRD1 is a fine mediator of cardiomyocyte response to haemodynamic load in the developing and adult heart. Increased ANKRD1 levels are sufficient to initiate an altered cellular phenotype, which is progressively exacerbated into a pathological organ response by the high ventricular workload during postnatal life. Our study defines for the first time a unifying picture for ANKRD1 role in heart development and disease and provides the first mechanistic link between ANKRD1 overexpression and cardiac disease onset.
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Affiliation(s)
- Nicoletta Piroddi
- Department of Experimental and Clinical Medicine, University of Florence, 50134 Florence, Italy
| | - Paola Pesce
- Department of Medicine, University of Padua, 35121 Padua, Italy
| | - Beatrice Scellini
- Department of Experimental and Clinical Medicine, University of Florence, 50134 Florence, Italy
| | - Stefano Manzini
- Department of Pharmacological and Biomolecular Sciences, University of Milan, 20133 Milan, Italy
| | - Giulia S Ganzetti
- Department of Pharmacological and Biomolecular Sciences, University of Milan, 20133 Milan, Italy
| | - Ileana Badi
- Department of Biotechnology and Life Sciences, University of Insubria, 21100 Varese, Italy.,Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DU, UK
| | - Michela Menegollo
- Department of Biomedical Sciences, University of Padua, 35121 Padua, Italy
| | - Virginia Cora
- Department of Biomedical Sciences, University of Padua, 35121 Padua, Italy
| | - Simone Tiso
- Department of Biomedical Sciences, University of Padua, 35121 Padua, Italy
| | - Raffaella Cinquetti
- Department of Biotechnology and Life Sciences, University of Insubria, 21100 Varese, Italy
| | - Laura Monti
- Department of Biotechnology and Life Sciences, University of Insubria, 21100 Varese, Italy
| | - Giulia Chiesa
- Department of Pharmacological and Biomolecular Sciences, University of Milan, 20133 Milan, Italy
| | - Steven B Bleyl
- Department of Pediatrics, University of Utah, Salt Lake City, 84132 UT, USA
| | - Marco Busnelli
- Department of Pharmacological and Biomolecular Sciences, University of Milan, 20133 Milan, Italy
| | - Federica Dellera
- Department of Pharmacological and Biomolecular Sciences, University of Milan, 20133 Milan, Italy
| | - Daniele Bruno
- Department of Biotechnology and Life Sciences, University of Insubria, 21100 Varese, Italy
| | - Federico Caicci
- Department of Biology, University of Padua, 35121 Padua, Italy
| | - Annalisa Grimaldi
- Department of Biotechnology and Life Sciences, University of Insubria, 21100 Varese, Italy
| | - Roberto Taramelli
- Department of Biotechnology and Life Sciences, University of Insubria, 21100 Varese, Italy
| | - Lucia Manni
- Department of Biology, University of Padua, 35121 Padua, Italy
| | - David Sacerdoti
- Department of Medicine, University of Padua, 35121 Padua, Italy
| | - Chiara Tesi
- Department of Experimental and Clinical Medicine, University of Florence, 50134 Florence, Italy
| | - Corrado Poggesi
- Department of Experimental and Clinical Medicine, University of Florence, 50134 Florence, Italy
| | - Simonetta Ausoni
- Department of Biomedical Sciences, University of Padua, 35121 Padua, Italy
| | - Francesco Acquati
- Department of Biotechnology and Life Sciences, University of Insubria, 21100 Varese, Italy
| | - Marina Campione
- Department of Biomedical Sciences, University of Padua, 35121 Padua, Italy.,CNR-Neuroscience Institute, 35121 Padua, Italy
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17
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Ihara K, Sasano T, Hiraoka Y, Togo-Ohno M, Soejima Y, Sawabe M, Tsuchiya M, Ogawa H, Furukawa T, Kuroyanagi H. A missense mutation in the RSRSP stretch of Rbm20 causes dilated cardiomyopathy and atrial fibrillation in mice. Sci Rep 2020; 10:17894. [PMID: 33110103 PMCID: PMC7591520 DOI: 10.1038/s41598-020-74800-8] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Accepted: 10/06/2020] [Indexed: 02/07/2023] Open
Abstract
Dilated cardiomyopathy (DCM) is a fatal heart disease characterized by left ventricular dilatation and cardiac dysfunction. Recent genetic studies on DCM have identified causative mutations in over 60 genes, including RBM20, which encodes a regulator of heart-specific splicing. DCM patients with RBM20 mutations have been reported to present with more severe cardiac phenotypes, including impaired cardiac function, atrial fibrillation (AF), and ventricular arrhythmias leading to sudden cardiac death, compared to those with mutations in the other genes. An RSRSP stretch of RBM20, a hotspot of missense mutations found in patients with idiopathic DCM, functions as a crucial part of its nuclear localization signals. However, the relationship between mutations in the RSRSP stretch and cardiac phenotypes has never been assessed in an animal model. Here, we show that Rbm20 mutant mice harboring a missense mutation S637A in the RSRSP stretch, mimicking that in a DCM patient, demonstrated severe cardiac dysfunction and spontaneous AF and ventricular arrhythmias mimicking the clinical state in patients. In contrast, Rbm20 mutant mice with frame-shifting deletion demonstrated less severe phenotypes, although loss of RBM20-dependent alternative splicing was indistinguishable. RBM20S637A protein cannot be localized to the nuclear speckles, but accumulated in cytoplasmic, perinuclear granule-like structures in cardiomyocytes, which might contribute to the more severe cardiac phenotypes.
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Affiliation(s)
- Kensuke Ihara
- Department of Bio-informational Pharmacology, Medical Research Institute, Tokyo Medical and Dental University (TMDU), Tokyo, 113-8510, Japan. .,Department of Cardiovascular Medicine, Tokyo Medical and Dental University (TMDU), Tokyo, 113-8510, Japan.
| | - Tetsuo Sasano
- Department of Cardiovascular Medicine, Tokyo Medical and Dental University (TMDU), Tokyo, 113-8510, Japan
| | - Yuichi Hiraoka
- Laboratory of Molecular Neuroscience, Medical Research Institute, Tokyo Medical and Dental University (TMDU), Tokyo, 113-8510, Japan
| | - Marina Togo-Ohno
- Laboratory of Gene Expression, Medical Research Institute, Tokyo Medical and Dental University (TMDU), Tokyo, 113-8510, Japan
| | - Yurie Soejima
- Department of Molecular Pathology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), Tokyo, 113-8510, Japan
| | - Motoji Sawabe
- Department of Molecular Pathology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), Tokyo, 113-8510, Japan
| | - Megumi Tsuchiya
- Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka, 565-0871, Japan
| | - Hidesato Ogawa
- Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka, 565-0871, Japan
| | - Tetsushi Furukawa
- Department of Bio-informational Pharmacology, Medical Research Institute, Tokyo Medical and Dental University (TMDU), Tokyo, 113-8510, Japan
| | - Hidehito Kuroyanagi
- Laboratory of Gene Expression, Medical Research Institute, Tokyo Medical and Dental University (TMDU), Tokyo, 113-8510, Japan.
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18
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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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19
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Chen MP, Kiduko SA, Saad NS, Canan BD, Kilic A, Mohler PJ, Janssen PML. Stretching single titin molecules from failing human hearts reveals titin's role in blunting cardiac kinetic reserve. Cardiovasc Res 2020; 116:127-137. [PMID: 30778519 DOI: 10.1093/cvr/cvz043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Revised: 11/08/2018] [Accepted: 02/13/2019] [Indexed: 11/15/2022] Open
Abstract
AIMS Heart failure (HF) patients commonly experience symptoms primarily during elevated heart rates, as a result of physical activities or stress. A main determinant of diastolic passive tension, the elastic sarcomeric protein titin, has been shown to be associated with HF, with unresolved involvement regarding its role at different heart rates. To determine whether titin is playing a role in the heart rate (frequency-) dependent acceleration of relaxation (FDAR). W, we studied the FDAR responses in live human left ventricular cardiomyocytes and the corresponding titin-based passive tension (TPT) from failing and non-failing human hearts. METHODS AND RESULTS Using atomic force, we developed a novel single-molecule force spectroscopy approach to detect TPT based on the frequency-modulated cardiac cycle. Mean TPT reduced upon an increased heart rate in non-failing human hearts, while this reduction was significantly blunted in failing human hearts. These mechanical changes in the titin distal Ig domain significantly correlated with the frequency-dependent relaxation kinetics of human cardiomyocytes obtained from the corresponding hearts. Furthermore, the data suggested that the higher the TPT, the faster the cardiomyocytes relaxed, but the lower the potential of myocytes to speed up relaxation at a higher heart rate. Such poorer FDAR response was also associated with a lesser reduction or a bigger increase in TPT upon elevated heart rate. CONCLUSIONS Our study established a novel approach in detecting dynamic heart rate relevant tension changes physiologically on native titin domains. Using this approach, the data suggested that the regulation of kinetic reserve in cardiac relaxation and its pathological changes were associated with the intensity and dynamic changes of passive tension by titin.
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Affiliation(s)
- Mei-Pian Chen
- Department of Physiology and Cell Biology, The Ohio State University, Hamilton Hall 207a, 1645 Neil Avenue, Columbus, OH 43210, USA.,Dorothy M. Davis Heart and Lung Research Institute, 473 W 12th Ave, Columbus, OH 43210 USA
| | - Salome A Kiduko
- Department of Physiology and Cell Biology, The Ohio State University, Hamilton Hall 207a, 1645 Neil Avenue, Columbus, OH 43210, USA.,Dorothy M. Davis Heart and Lung Research Institute, 473 W 12th Ave, Columbus, OH 43210 USA
| | - Nancy S Saad
- Department of Physiology and Cell Biology, The Ohio State University, Hamilton Hall 207a, 1645 Neil Avenue, Columbus, OH 43210, USA.,Dorothy M. Davis Heart and Lung Research Institute, 473 W 12th Ave, Columbus, OH 43210 USA.,Department of Pharmacology and Toxicology, Faculty of Pharmacy, Helwan University, Cairo, Egypt
| | - Benjamin D Canan
- Department of Physiology and Cell Biology, The Ohio State University, Hamilton Hall 207a, 1645 Neil Avenue, Columbus, OH 43210, USA.,Dorothy M. Davis Heart and Lung Research Institute, 473 W 12th Ave, Columbus, OH 43210 USA
| | - Ahmet Kilic
- Division of Cardiothoracic Surgery, Department of Surgery, The Ohio State University Wexner Medical Center, 410 W 10th Ave, Columbus, OH 43210, USA
| | - Peter J Mohler
- Department of Physiology and Cell Biology, The Ohio State University, Hamilton Hall 207a, 1645 Neil Avenue, Columbus, OH 43210, USA.,Dorothy M. Davis Heart and Lung Research Institute, 473 W 12th Ave, Columbus, OH 43210 USA.,Department of Internal Medicine, The Ohio State University Wexner Medical Center, 395 W 12th Ave, Columbus, OH 43210, USA
| | - Paul M L Janssen
- Department of Physiology and Cell Biology, The Ohio State University, Hamilton Hall 207a, 1645 Neil Avenue, Columbus, OH 43210, USA.,Dorothy M. Davis Heart and Lung Research Institute, 473 W 12th Ave, Columbus, OH 43210 USA.,Department of Internal Medicine, The Ohio State University Wexner Medical Center, 395 W 12th Ave, Columbus, OH 43210, USA
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20
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van der Pijl RJ, Hudson B, Granzier-Nakajima T, Li F, Knottnerus AM, Smith J, Chung CS, Gotthardt M, Granzier HL, Ottenheijm CAC. Deleting Titin's C-Terminal PEVK Exons Increases Passive Stiffness, Alters Splicing, and Induces Cross-Sectional and Longitudinal Hypertrophy in Skeletal Muscle. Front Physiol 2020; 11:494. [PMID: 32547410 PMCID: PMC7274174 DOI: 10.3389/fphys.2020.00494] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Accepted: 04/23/2020] [Indexed: 12/13/2022] Open
Abstract
The Proline, Glutamate, Valine and Lysine-rich (PEVK) region of titin constitutes an entropic spring that provides passive tension to striated muscle. To study the functional and structural repercussions of a small reduction in the size of the PEVK region, we investigated skeletal muscles of a mouse with the constitutively expressed C-terminal PEVK exons 219-225 deleted, the TtnΔ219-225 model (MGI: TtnTM 2.1Mgot ). Based on this deletion, passive tension in skeletal muscle was predicted to be increased by ∼17% (sarcomere length 3.0 μm). In contrast, measured passive tension (sarcomere length 3.0 μm) in both soleus and EDL muscles was increased 53 ± 11% and 62 ± 4%, respectively. This unexpected increase was due to changes in titin, not to alterations in the extracellular matrix, and is likely caused by co-expression of two titin isoforms in TtnΔ219-225 muscles: a larger isoform that represents the TtnΔ219-225 N2A titin and a smaller isoform, referred to as N2A2. N2A2 represents a splicing adaption with reduced expression of spring element exons, as determined by titin exon microarray analysis. Maximal tetanic tension was increased in TtnΔ219-225 soleus muscle (WT 240 ± 9; TtnΔ219-225 276 ± 17 mN/mm2), but was reduced in EDL muscle (WT 315 ± 9; TtnΔ219-225 280 ± 14 mN/mm2). The changes in active tension coincided with a switch toward slow fiber types and, unexpectedly, faster kinetics of tension generation and relaxation. Functional overload (FO; ablation) and hindlimb suspension (HS; unloading) experiments were also conducted. TtnΔ219-225 mice showed increases in both longitudinal hypertrophy (increased number of sarcomeres in series) and cross-sectional hypertrophy (increased number of sarcomeres in parallel) in response to FO and attenuated cross-sectional atrophy in response to HS. In summary, slow- and fast-twitch muscles in a mouse model devoid of titin's PEVK exons 219-225 have high passive tension, due in part to alterations elsewhere in splicing of titin's spring region, increased kinetics of tension generation and relaxation, and altered trophic responses to both functional overload and unloading. This implicates titin's C-terminal PEVK region in regulating passive and active muscle mechanics and muscle plasticity.
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Affiliation(s)
- Robbert J van der Pijl
- Cellular and Molecular Medicine, University of Arizona, Tucson, AZ, United States.,Department of Physiology, Amsterdam UMC, Amsterdam, Netherlands
| | - Brian Hudson
- Cellular and Molecular Medicine, University of Arizona, Tucson, AZ, United States
| | | | - Frank Li
- Cellular and Molecular Medicine, University of Arizona, Tucson, AZ, United States
| | - Anne M Knottnerus
- Cellular and Molecular Medicine, University of Arizona, Tucson, AZ, United States
| | - John Smith
- Cellular and Molecular Medicine, University of Arizona, Tucson, AZ, United States
| | - Charles S Chung
- Cellular and Molecular Medicine, University of Arizona, Tucson, AZ, United States.,Department of Physiology, Wayne State University, Detroit, MI, United States
| | - Michael Gotthardt
- Max-Delbruck-Center for Molecular Medicine, Berlin, Germany.,Cardiology, Virchow Klinikum, Charité University Medicine, Berlin, Germany
| | - Henk L Granzier
- Cellular and Molecular Medicine, University of Arizona, Tucson, AZ, United States
| | - Coen A C Ottenheijm
- Cellular and Molecular Medicine, University of Arizona, Tucson, AZ, United States.,Department of Physiology, Amsterdam UMC, Amsterdam, Netherlands
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21
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Fleming JR, Rigden DJ, Mayans O. The importance of chain context in assessing small nucleotide variants in titin: in silico case study of the I10-I11 tandem and its arrhythmic right ventricular cardiomyopathy linked position T2580. J Biomol Struct Dyn 2020; 39:3480-3490. [PMID: 32396765 DOI: 10.1080/07391102.2020.1768148] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Non-synonymous small nucleotide variations (nsSNVs) in the giant muscle protein, titin, have key roles in the development of several myopathologies. Although there is considerable motive to screen at-risk individuals for nsSNVs, to identify patients in early disease stages while therapeutic intervention is still possible, the clinical significance of most titin variations remains unclear. Therefore, there is a growing need to establish methods to classify nsSNVs in a simple, economic and rapid manner. Due to its strong correlation to arrhythmogenic right ventricular cardiomyopathy (ARVC), one particular mutation in titin-T2580I, located in the I10 immunoglobulin domain-has received considerable attention. Here, we use the I10-I11 tandem as a case study to explore the possible benefits of considering the titin chain context-i.e. domain interfaces-in the assessment of titin nsSNVs. Specifically, we investigate which exchanges mimic the conformational molecular phenotype of the T2580I mutation at the I10-I11 domain interface. Then, we computed a residue stability landscape for domains alone and in tandem to define a Domain Interface Score (DIS) which identifies several hotspot residues. Our findings suggest that the T2580 position is highly sensitive to exchange and that any variant found in this position should be considered with care. Furthermore, we conclude that the consideration of the higher order structure of the titin chain is important to gain accurate insights into the vulnerability of positions in linker regions and that titin nsSNV prediction benefits from a contextual analysis. Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- J R Fleming
- Department of Biology, University of Konstanz, Konstanz, Germany
| | - D J Rigden
- Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, UK
| | - O Mayans
- Department of Biology, University of Konstanz, Konstanz, Germany
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22
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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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23
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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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24
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Saucerman JJ, Tan PM, Buchholz KS, McCulloch AD, Omens JH. Mechanical regulation of gene expression in cardiac myocytes and fibroblasts. Nat Rev Cardiol 2019; 16:361-378. [PMID: 30683889 PMCID: PMC6525041 DOI: 10.1038/s41569-019-0155-8] [Citation(s) in RCA: 110] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The intact heart undergoes complex and multiscale remodelling processes in response to altered mechanical cues. Remodelling of the myocardium is regulated by a combination of myocyte and non-myocyte responses to mechanosensitive pathways, which can alter gene expression and therefore function in these cells. Cellular mechanotransduction and its downstream effects on gene expression are initially compensatory mechanisms during adaptations to the altered mechanical environment, but under prolonged and abnormal loading conditions, they can become maladaptive, leading to impaired function and cardiac pathologies. In this Review, we summarize mechanoregulated pathways in cardiac myocytes and fibroblasts that lead to altered gene expression and cell remodelling under physiological and pathophysiological conditions. Developments in systems modelling of the networks that regulate gene expression in response to mechanical stimuli should improve integrative understanding of their roles in vivo and help to discover new combinations of drugs and device therapies targeting mechanosignalling in heart disease.
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Affiliation(s)
- Jeffrey J Saucerman
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, USA
| | - Philip M Tan
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, USA
| | - Kyle S Buchholz
- Departments of Bioengineering and Medicine, University of California San Diego, La Jolla, CA, USA
| | - Andrew D McCulloch
- Departments of Bioengineering and Medicine, University of California San Diego, La Jolla, CA, USA.
| | - Jeffrey H Omens
- Departments of Bioengineering and Medicine, University of California San Diego, La Jolla, CA, USA
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25
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Abstract
PURPOSE OF REVIEW To describe recent advancements in cardiovascular genetics made possible by leveraging next-generation sequencing (NGS), and to provide a framework for practical applications of genetic testing for hypertrophic (HCM), dilated (DCM), and arrhythmogenic right ventricular cardiomyopathies (ARVC). RECENT FINDINGS The availability of NGS has made possible extensive reference databases. These, combined with recent initiatives to compile previously siloed commercial and research cardiomyopathy data sets, provide a more powerful and precise approach to cardiovascular genetic medicine. HCM, DCM and ARVC are cardiomyopathies usually inherited in an autosomal dominant pattern. Over 1000 pathogenic mutations have been identified: HCM in genes encoding proteins of the sarcomere, and ARVC in genes encoding proteins of the desosome. DCM shows considerably more diverse ontology, suggesting more complex pathophysiology. In addition to allelic and locus heterogeneity, reduced penetrance and variable expressivity among affected individuals can make the clinical diagnosis of 'familial cardiomyopathy' less apparent. SUMMARY Current evidence supports the use of genetic testing in clinical practice to improve risk stratification for clinically affected patients and their at-risk relatives for hypertrophic, arrhythmogenic, and dilated cardiomyopathies. Understanding how to implement genetic testing and to evaluate at-risk family members, provide clinical implications of results as well as discuss limitations of genetic testing is essential to improving personalized care.
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26
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Watson SA, Duff J, Bardi I, Zabielska M, Atanur SS, Jabbour RJ, Simon A, Tomas A, Smolenski RT, Harding SE, Perbellini F, Terracciano CM. Biomimetic electromechanical stimulation to maintain adult myocardial slices in vitro. Nat Commun 2019; 10:2168. [PMID: 31092830 PMCID: PMC6520377 DOI: 10.1038/s41467-019-10175-3] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Accepted: 04/24/2019] [Indexed: 01/01/2023] Open
Abstract
Adult cardiac tissue undergoes a rapid process of dedifferentiation when cultured outside the body. The in vivo environment, particularly constant electromechanical stimulation, is fundamental to the regulation of cardiac structure and function. We investigated the role of electromechanical stimulation in preventing culture-induced dedifferentiation of adult cardiac tissue using rat, rabbit and human heart failure myocardial slices. Here we report that the application of a preload equivalent to sarcomere length (SL) = 2.2 μm is optimal for the maintenance of rat myocardial slice structural, functional and transcriptional properties at 24 h. Gene sets associated with the preservation of structure and function are activated, while gene sets involved in dedifferentiation are suppressed. The maximum contractility of human heart failure myocardial slices at 24 h is also optimally maintained at SL = 2.2 μm. Rabbit myocardial slices cultured at SL = 2.2 μm remain stable for 5 days. This approach substantially prolongs the culture of adult cardiac tissue in vitro.
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Affiliation(s)
- Samuel A Watson
- National Heart & Lung Institute, Imperial College London, London, W12 0NN, UK
| | - James Duff
- National Heart & Lung Institute, Imperial College London, London, W12 0NN, UK
| | - Ifigeneia Bardi
- National Heart & Lung Institute, Imperial College London, London, W12 0NN, UK
| | - Magdalena Zabielska
- Department of Biochemistry, Medical University of Gdańsk, Gdańsk, 80-210, Poland
| | - Santosh S Atanur
- Faculty of Medicine, Department of Medicine, Imperial College London, London, SW7 2AZ, UK
| | - Richard J Jabbour
- National Heart & Lung Institute, Imperial College London, London, W12 0NN, UK
| | - André Simon
- Department of Cardiothoracic Transplantation & Mechanical Circulatory Support, Royal Brompton & Harefield NHS Foundation Trust, Harefield, UB9 6JH, UK
| | - Alejandra Tomas
- Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Imperial College London, London, W12 0NN, UK
| | - Ryszard T Smolenski
- Department of Biochemistry, Medical University of Gdańsk, Gdańsk, 80-210, Poland
| | - Sian E Harding
- National Heart & Lung Institute, Imperial College London, London, W12 0NN, UK
| | - Filippo Perbellini
- National Heart & Lung Institute, Imperial College London, London, W12 0NN, UK.
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27
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Koser F, Loescher C, Linke WA. Posttranslational modifications of titin from cardiac muscle: how, where, and what for? FEBS J 2019; 286:2240-2260. [PMID: 30989819 PMCID: PMC6850032 DOI: 10.1111/febs.14854] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Revised: 02/27/2019] [Accepted: 04/13/2019] [Indexed: 12/11/2022]
Abstract
Titin is a giant elastic protein expressed in the contractile units of striated muscle cells, including the sarcomeres of cardiomyocytes. The last decade has seen enormous progress in our understanding of how titin molecular elasticity is modulated in a dynamic manner to help cardiac sarcomeres adjust to the varying hemodynamic demands on the heart. Crucial events mediating the rapid modulation of cardiac titin stiffness are post‐translational modifications (PTMs) of titin. In this review, we first recollect what is known from earlier and recent work on the molecular mechanisms of titin extensibility and force generation. The main goal then is to provide a comprehensive overview of current insight into the relationship between titin PTMs and cardiomyocyte stiffness, notably the effect of oxidation and phosphorylation of titin spring segments on titin stiffness. A synopsis is given of which type of oxidative titin modification can cause which effect on titin stiffness. A large part of the review then covers the mechanically relevant phosphorylation sites in titin, their location along the elastic segment, and the protein kinases and phosphatases known to target these sites. We also include a detailed coverage of the complex changes in phosphorylation at specific titin residues, which have been reported in both animal models of heart disease and in human heart failure, and their correlation with titin‐based stiffness alterations. Knowledge of the relationship between titin PTMs and titin elasticity can be exploited in the search for therapeutic approaches aimed at softening the pathologically stiffened myocardium in heart failure patients.
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28
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29
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Mijailovich SM, Stojanovic B, Nedic D, Svicevic M, Geeves MA, Irving TC, Granzier HL. Nebulin and titin modulate cross-bridge cycling and length-dependent calcium sensitivity. J Gen Physiol 2019; 151:680-704. [PMID: 30948421 PMCID: PMC6504291 DOI: 10.1085/jgp.201812165] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Revised: 01/15/2019] [Accepted: 03/03/2019] [Indexed: 12/13/2022] Open
Abstract
Various mutations in the structural proteins nebulin and titin that are present in human disease are known to affect the contractility of striated muscle. Loss of nebulin is associated with reduced actin filament length and impairment of myosin binding to actin, whereas titin is thought to regulate muscle passive elasticity and is likely involved in length-dependent activation. Here, we sought to assess the modulation of muscle function by these sarcomeric proteins by using the computational platform muscle simulation code (MUSICO) to quantitatively separate the effects of structural changes, kinetics of cross-bridge cycling, and calcium sensitivity of the thin filaments. The simulations show that variation in thin filament length cannot by itself account for experimental observations of the contractility in nebulin-deficient muscle, but instead must be accompanied by a decreased myosin binding rate. Additionally, to match the observed calcium sensitivity, the rate of TnI detachment from actin needed to be increased. Simulations for cardiac muscle provided quantitative estimates of the effects of different titin-based passive elasticities on muscle force and activation in response to changes in sarcomere length and interfilament lattice spacing. Predicted force-pCa relations showed a decrease in both active tension and sensitivity to calcium with a decrease in passive tension and sarcomere length. We conclude that this behavior is caused by partial redistribution of the muscle load between active muscle force and titin-dependent passive force, and also by redistribution of stretch along the thin filament, which together modulate the release of TnI from actin. These data help advance understanding of how nebulin and titin mutations affect muscle function.
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Affiliation(s)
- Srboljub M Mijailovich
- Department of Chemistry and Chemical Biology, Northeastern University, Boston, MA .,Department of Biological Sciences, Illinois Institute of Technology, Chicago, IL
| | - Boban Stojanovic
- University of Kragujevac, Faculty of Science, Kragujevac, Serbia
| | - Djordje Nedic
- University of Kragujevac, Faculty of Science, Kragujevac, Serbia
| | - Marina Svicevic
- University of Kragujevac, Faculty of Science, Kragujevac, Serbia
| | - Michael A Geeves
- Department of Biosciences, University of Kent, Canterbury, Kent, UK
| | - Thomas C Irving
- Department of Biological Sciences, Illinois Institute of Technology, Chicago, IL
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30
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Kellermayer D, Smith JE, Granzier H. Titin mutations and muscle disease. Pflugers Arch 2019; 471:673-682. [PMID: 30919088 DOI: 10.1007/s00424-019-02272-5] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Accepted: 03/11/2019] [Indexed: 12/12/2022]
Abstract
The introduction of next-generation sequencing technology has revealed that mutations in the gene that encodes titin (TTN) are linked to multiple skeletal and cardiac myopathies. The most prominent of these myopathies is dilated cardiomyopathy (DCM). Over 60 genes are linked to the etiology of DCM, but by far, the leading cause of DCM is mutations in TTN with truncating variants in TTN (TTNtvs) associated with familial DCM in ∼ 20% of the cases. Titin is a large (3-4 MDa) and abundant protein that forms the third myofilament type of striated muscle where it spans half the sarcomere, from the Z-disk to the M-line. The underlying mechanisms by which titin mutations induce disease are poorly understood and targeted therapies are not available. Here, we review what is known about TTN mutations in muscle disease, with a major focus on DCM. We highlight that exon skipping might provide a possible therapeutic avenue to address diseases that arise from TTNtvs.
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Affiliation(s)
- Dalma Kellermayer
- Department of Cellular and Molecular Medicine, University of Arizona, MRB 325. 1656 E Mabel Street, Tucson, AZ, 85724-5217, USA.,Sarver Molecular Cardiovascular Research Program, University of Arizona, Tucson, AZ, 85721, USA
| | - John E Smith
- Department of Cellular and Molecular Medicine, University of Arizona, MRB 325. 1656 E Mabel Street, Tucson, AZ, 85724-5217, USA.,Sarver Molecular Cardiovascular Research Program, University of Arizona, Tucson, AZ, 85721, USA
| | - Henk Granzier
- Department of Cellular and Molecular Medicine, University of Arizona, MRB 325. 1656 E Mabel Street, Tucson, AZ, 85724-5217, USA. .,Sarver Molecular Cardiovascular Research Program, University of Arizona, Tucson, AZ, 85721, USA.
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31
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Whitley JA, Ex-Willey AM, Marzolf DR, Ackermann MA, Tongen AL, Kokhan O, Wright NT. Obscurin is a semi-flexible molecule in solution. Protein Sci 2019; 28:717-726. [PMID: 30666746 DOI: 10.1002/pro.3578] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Accepted: 01/14/2019] [Indexed: 01/10/2023]
Abstract
Obscurin, a giant modular cytoskeletal protein, is comprised mostly of tandem immunoglobulin-like (Ig-like) domains. This architecture allows obscurin to connect distal targets within the cell. The linkers connecting the Ig domains are usually short (3-4 residues). The physical effect arising from these short linkers is not known; such linkers may lead to a stiff elongated molecule or, conversely, may lead to a more compact and dynamic structure. In an effort to better understand how linkers affect obscurin flexibility, and to better understand the physical underpinnings of this flexibility, here we study the structure and dynamics of four representative sets of dual obscurin Ig domains using experimental and computational techniques. We find in all cases tested that tandem obscurin Ig domains interact at the poles of each domain and tend to stay relatively extended in solution. NMR, SAXS, and MD simulations reveal that while tandem domains are elongated, they also bend and flex significantly. By applying this behavior to a simplified model, it becomes apparent obscurin can link targets more than 200 nm away. However, as targets get further apart, obscurin begins acting as a spring and requires progressively more energy to further elongate.
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Affiliation(s)
- Jacob A Whitley
- Department of Chemistry and Biochemistry, James Madison University, Harrisonburg, Virginia, 22807
| | - Aidan M Ex-Willey
- Department of Chemistry and Biochemistry, James Madison University, Harrisonburg, Virginia, 22807.,Department of Physiology and Cell Biology, Wexner Medical Center, Ohio State University, Columbus, Ohio, 43210
| | - Daniel R Marzolf
- Department of Chemistry and Biochemistry, James Madison University, Harrisonburg, Virginia, 22807
| | - Maegen A Ackermann
- Department of Physiology and Cell Biology, Wexner Medical Center, Ohio State University, Columbus, Ohio, 43210
| | - Anthony L Tongen
- Department of Mathematics and Statistics, James Madison University, Harrisonburg, Virginia, 22807
| | - Oleksandr Kokhan
- Department of Chemistry and Biochemistry, James Madison University, Harrisonburg, Virginia, 22807
| | - Nathan T Wright
- Department of Chemistry and Biochemistry, James Madison University, Harrisonburg, Virginia, 22807
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32
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Meyer G, Lieber RL. Muscle fibers bear a larger fraction of passive muscle tension in frogs compared with mice. J Exp Biol 2018; 221:jeb182089. [PMID: 30237238 PMCID: PMC6262763 DOI: 10.1242/jeb.182089] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Accepted: 09/14/2018] [Indexed: 02/03/2023]
Abstract
Differences in passive muscle mechanical properties between amphibians and mammals have led to differing hypotheses on the functional role of titin in skeletal muscle. Early studies of frog muscle clearly demonstrated intracellular load bearing by titin, but more recent structural and biological studies in mice have shown that titin may serve other functions. Here, we present biomechanical studies of isolated frog and mouse fibers, and fiber bundles to compare the relative importance of intracellular versus extracellular load bearing in these species. Mouse bundles exhibited increased modulus compared with fibers on the descending limb of the length-tension curve, reaching a 2.4-fold elevation at the longest sarcomere lengths. By contrast, frog fibers and bundles had approximately the same modulus at all sarcomere lengths tested. These findings suggest that in the mouse, both muscle fibers and the ECM are involved in bearing whole muscle passive tension, which is distinct from the load bearing process in frog muscle, where titin bears the majority of whole muscle passive tension.
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Affiliation(s)
- Gretchen Meyer
- Program in Physical Therapy, and Departments of Neurology, Biomedical Engineering and Orthopaedic Surgery, Washington University School of Medicine, St Louis, MO 63110, USA
| | - Richard L Lieber
- Shirley Ryan AbilityLab and Departments of Physical Medicine and Rehabilitation, Physiology and Biomedical Engineering, Northwestern University, Chicago, IL 60611, USA
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33
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RNA binding protein 24 deletion disrupts global alternative splicing and causes dilated cardiomyopathy. Protein Cell 2018; 10:405-416. [PMID: 30267374 PMCID: PMC6538757 DOI: 10.1007/s13238-018-0578-8] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Accepted: 08/24/2018] [Indexed: 01/08/2023] Open
Abstract
RNA splicing contributes to a broad spectrum of post-transcriptional gene regulation during normal development, as well as pathological manifestation of heart diseases. However, the functional role and regulation of splicing in heart failure remain poorly understood. RNA binding protein (RBP), a major component of the splicing machinery, is a critical factor in this process. RNA binding motif protein 24 (RBM24) is a tissue-specific RBP which is highly expressed in human and mouse heart. Previous studies demonstrated the functional role of RBM24 in the embryonic heart development. However, the role of RBM24 in postnatal heart development and heart disease has not been investigated. In this paper, using conditional RBM24 knockout mice, we demonstrated that ablation of RBM24 in postnatal heart led to rapidly progressive dilated cardiomyopathy (DCM), heart failure, and postnatal lethality. Global splicing profiling revealed that RBM24 regulated a network of genes related to cardiac function and diseases. Knockout of RBM24 resulted in misregulation of these splicing transitions which contributed to the subsequent development of cardiomyopathy. Notably, our analysis identified RBM24 as a splice factor that determined the splicing switch of a subset of genes in the sacomeric Z-disc complex, including Titin, the major disease gene of DCM and heart failure. Together, this study identifies regulation of RNA splicing by RBM24 as a potent player in remodeling of heart during postnatal development, and provides novel mechanistic insights to the pathogenesis of DCM.
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Phosphorylation of the RSRSP stretch is critical for splicing regulation by RNA-Binding Motif Protein 20 (RBM20) through nuclear localization. Sci Rep 2018; 8:8970. [PMID: 29895960 PMCID: PMC5997748 DOI: 10.1038/s41598-018-26624-w] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Accepted: 05/14/2018] [Indexed: 11/08/2022] Open
Abstract
RBM20 is a major regulator of heart-specific alternative pre-mRNA splicing of TTN encoding a giant sarcomeric protein titin. Mutation in RBM20 is linked to autosomal-dominant familial dilated cardiomyopathy (DCM), yet most of the RBM20 missense mutations in familial and sporadic cases were mapped to an RSRSP stretch in an arginine/serine-rich region of which function remains unknown. In the present study, we identified an R634W missense mutation within the stretch and a G1031X nonsense mutation in cohorts of DCM patients. We demonstrate that the two serine residues in the RSRSP stretch are constitutively phosphorylated and mutations in the stretch disturb nuclear localization of RBM20. Rbm20S637A knock-in mouse mimicking an S635A mutation reported in a familial case showed a remarkable effect on titin isoform expression like in a patient carrying the mutation. These results revealed the function of the RSRSP stretch as a critical part of a nuclear localization signal and offer the Rbm20S637A mouse as a good model for in vivo study.
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Stretch your heart-but not too far: The role of titin mutations in dilated cardiomyopathy. J Thorac Cardiovasc Surg 2018; 156:209-214. [PMID: 29685583 DOI: 10.1016/j.jtcvs.2017.10.160] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Revised: 09/29/2017] [Accepted: 10/24/2017] [Indexed: 12/23/2022]
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Chopra A, Kutys ML, Zhang K, Polacheck WJ, Sheng CC, Luu RJ, Eyckmans J, Hinson JT, Seidman JG, Seidman CE, Chen CS. Force Generation via β-Cardiac Myosin, Titin, and α-Actinin Drives Cardiac Sarcomere Assembly from Cell-Matrix Adhesions. Dev Cell 2018; 44:87-96.e5. [PMID: 29316444 DOI: 10.1016/j.devcel.2017.12.012] [Citation(s) in RCA: 104] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Revised: 10/16/2017] [Accepted: 12/11/2017] [Indexed: 12/26/2022]
Abstract
Truncating mutations in the sarcomere protein titin cause dilated cardiomyopathy due to sarcomere insufficiency. However, it remains mechanistically unclear how these mutations decrease sarcomere content in cardiomyocytes. Utilizing human induced pluripotent stem cell-derived cardiomyocytes, CRISPR/Cas9, and live microscopy, we characterize the fundamental mechanisms of human cardiac sarcomere formation. We observe that sarcomerogenesis initiates at protocostameres, sites of cell-extracellular matrix adhesion, where nucleation and centripetal assembly of α-actinin-2-containing fibers provide a template for the fusion of Z-disk precursors, Z bodies, and subsequent striation. We identify that β-cardiac myosin-titin-protocostamere form an essential mechanical connection that transmits forces required to direct α-actinin-2 centripetal fiber assembly and sarcomere formation. Titin propagates diastolic traction stresses from β-cardiac myosin, but not α-cardiac myosin or non-muscle myosin II, to protocostameres during sarcomerogenesis. Ablating protocostameres or decoupling titin from protocostameres abolishes sarcomere assembly. Together these results identify the mechanical and molecular components critical for human cardiac sarcomerogenesis.
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Affiliation(s)
- Anant Chopra
- Department of Biomedical Engineering, Boston University, Boston, MA 02215, USA; The Wyss Institute for Biologically Inspired Engineering at Harvard University, Boston, MA 02115, USA
| | - Matthew L Kutys
- Department of Biomedical Engineering, Boston University, Boston, MA 02215, USA; The Wyss Institute for Biologically Inspired Engineering at Harvard University, Boston, MA 02115, USA
| | - Kehan Zhang
- Department of Biomedical Engineering, Boston University, Boston, MA 02215, USA; The Wyss Institute for Biologically Inspired Engineering at Harvard University, Boston, MA 02115, USA
| | - William J Polacheck
- Department of Biomedical Engineering, Boston University, Boston, MA 02215, USA; The Wyss Institute for Biologically Inspired Engineering at Harvard University, Boston, MA 02115, USA
| | - Calvin C Sheng
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Rebeccah J Luu
- Department of Biomedical Engineering, Boston University, Boston, MA 02215, USA
| | - Jeroen Eyckmans
- Department of Biomedical Engineering, Boston University, Boston, MA 02215, USA; The Wyss Institute for Biologically Inspired Engineering at Harvard University, Boston, MA 02115, USA
| | - J Travis Hinson
- The Jackson Laboratory for Genomic Medicine, Farmington, CT 06032, USA; Cardiology Center, University of Connecticut Health, Farmington, CT 06030, USA.
| | - Jonathan G Seidman
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA; Division of Cardiovascular Medicine, Brigham and Women's Hospital, Boston, MA 02115, USA.
| | - Christine E Seidman
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA; Division of Cardiovascular Medicine, Brigham and Women's Hospital, Boston, MA 02115, USA; Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA.
| | - Christopher S Chen
- Department of Biomedical Engineering, Boston University, Boston, MA 02215, USA; The Wyss Institute for Biologically Inspired Engineering at Harvard University, Boston, MA 02115, USA.
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37
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Zhu C, Guo W. Detection and quantification of the giant protein titin by SDS-agarose gel electrophoresis. MethodsX 2017; 4:320-327. [PMID: 29872636 PMCID: PMC5986978 DOI: 10.1016/j.mex.2017.09.007] [Citation(s) in RCA: 14] [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: 07/03/2017] [Accepted: 09/26/2017] [Indexed: 11/21/2022] Open
Abstract
Titin, a giant sarcomeric protein, is involved in the generation of passive tension during muscle contraction, assembly and stability of the sarcomere in striated muscles. Titin gene produces numerous titin protein isoforms with different sizes (∼3-4 MDa) resulting from alternative splicing. To study titin and titin isoform changes under disease conditions, the method to detect and quantify titin protein isoforms is needed. The method reported here is a 1% vertical SDS-agarose gel electrophoresis system that can solubilize, detect and quantify various titin isoform sizes. Sodium dodecyl sulfate (SDS)-agarose gel electrophoresis is an important tool in revealing the size and quantity of giant proteins in the sarcomere. In this method article, heart tissues were dissolved in urea-thiourea-glycerol sample buffer. Muscle proteins were resolved on 1% SDS-agarose gels that were silver-stained subsequently. Titin isoform bands with different sizes were separated on the gel. At the end, we also validated the method for large protein detection. Our results indicated that this electrophoresis method is efficient to study the transitions in titin isoforms. •This method provides efficient protein extraction with urea-thiourea-glycerol buffer from hard tissues such as striated muscles•This method provides an efficient way to separate large proteins over 500 kDa•Combining with silver staining, our method can detect large protein isoforms and quantify the separated protein bands.
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Affiliation(s)
| | - Wei Guo
- Animal Science, University of Wyoming, Laramie, WY 82071, USA
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Abstract
Nonischemic dilated cardiomyopathy (DCM) often has a genetic pathogenesis. Because of the large number of genes and alleles attributed to DCM, comprehensive genetic testing encompasses ever-increasing gene panels. Genetic diagnosis can help predict prognosis, especially with regard to arrhythmia risk for certain subtypes. Moreover, cascade genetic testing in family members can identify those who are at risk or with early stage disease, offering the opportunity for early intervention. This review will address diagnosis and management of DCM, including the role of genetic evaluation. We will also overview distinct genetic pathways linked to DCM and their pathogenetic mechanisms. Historically, cardiac morphology has been used to classify cardiomyopathy subtypes. Determining genetic variants is emerging as an additional adjunct to help further refine subtypes of DCM, especially where arrhythmia risk is increased, and ultimately contribute to clinical management.
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Affiliation(s)
- Elizabeth M McNally
- From the Center for Genetic Medicine, Northwestern University Feinberg School of Medicine, Chicago IL (E.M.M.); and Cardiovascular Institute, University of Colorado Anschutz Medical Campus, Aurora (L.M.).
| | - Luisa Mestroni
- From the Center for Genetic Medicine, Northwestern University Feinberg School of Medicine, Chicago IL (E.M.M.); and Cardiovascular Institute, University of Colorado Anschutz Medical Campus, Aurora (L.M.).
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Hu X, Margadant FM, Yao M, Sheetz MP. Molecular stretching modulates mechanosensing pathways. Protein Sci 2017; 26:1337-1351. [PMID: 28474792 DOI: 10.1002/pro.3188] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Revised: 04/26/2017] [Accepted: 04/27/2017] [Indexed: 01/21/2023]
Abstract
For individual cells in tissues to create the diverse forms of biological organisms, it is necessary that they must reliably sense and generate the correct forces over the correct distances and directions. There is considerable evidence that the mechanical aspects of the cellular microenvironment provide critical physical parameters to be sensed. How proteins sense forces and cellular geometry to create the correct morphology is not understood in detail but protein unfolding appears to be a major component in force and displacement sensing. Thus, the crystallographic structure of a protein domain provides only a starting point to then analyze what will be the effects of physiological forces through domain unfolding or catch-bond formation. In this review, we will discuss the recent studies of cytoskeletal and adhesion proteins that describe protein domain dynamics. Forces applied to proteins can activate or inhibit enzymes, increase or decrease protein-protein interactions, activate or inhibit protein substrates, induce catch bonds and regulate interactions with membranes or nucleic acids. Further, the dynamics of stretch-relaxation can average forces or movements to reliably regulate morphogenic movements. In the few cases where single molecule mechanics are studied under physiological conditions such as titin and talin, there are rapid cycles of stretch-relaxation that produce mechanosensing signals. Fortunately, the development of new single molecule and super-resolution imaging methods enable the analysis of single molecule mechanics in physiologically relevant conditions. Thus, we feel that stereotypical changes in cell and tissue shape involve mechanosensing that can be analyzed at the nanometer level to determine the molecular mechanisms involved.
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Affiliation(s)
- Xian Hu
- Mechanobiology Institute, National University of Singapore, Singapore, 117411.,Department of Biosciences, University of Oslo, Oslo, 0316, Norway
| | | | - Mingxi Yao
- Mechanobiology Institute, National University of Singapore, Singapore, 117411
| | - Michael Patrick Sheetz
- Mechanobiology Institute, National University of Singapore, Singapore, 117411.,Department of Biological Sciences, University of Columbia, New York, 10027
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Lindstedt S, Nishikawa K. Huxleys’ Missing Filament: Form and Function of Titin in Vertebrate Striated Muscle. Annu Rev Physiol 2017; 79:145-166. [DOI: 10.1146/annurev-physiol-022516-034152] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Stan Lindstedt
- Center for Bioengineering Innovation, Northern Arizona University, Flagstaff, Arizona 86011-4185
| | - Kiisa Nishikawa
- Department of Biological Sciences, Northern Arizona University, Flagstaff, Arizona 86011-4185;
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α-Actinin/titin interaction: A dynamic and mechanically stable cluster of bonds in the muscle Z-disk. Proc Natl Acad Sci U S A 2017; 114:1015-1020. [PMID: 28096424 DOI: 10.1073/pnas.1612681114] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Stable anchoring of titin within the muscle Z-disk is essential for preserving muscle integrity during passive stretching. One of the main candidates for anchoring titin in the Z-disk is the actin cross-linker α-actinin. The calmodulin-like domain of α-actinin binds to the Z-repeats of titin. However, the mechanical and kinetic properties of this important interaction are still unknown. Here, we use a dual-beam optical tweezers assay to study the mechanics of this interaction at the single-molecule level. A single interaction of α-actinin and titin turns out to be surprisingly weak if force is applied. Depending on the direction of force application, the unbinding forces can more than triple. Our results suggest a model where multiple α-actinin/Z-repeat interactions cooperate to ensure long-term stable titin anchoring while allowing the individual components to exchange dynamically.
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Abstract
In this review we discuss the history and the current state of ideas related to the mechanism of size regulation of the thick (myosin) and thin (actin) filaments in vertebrate striated muscles. Various hypotheses have been considered during of more than half century of research, recently mostly involving titin and nebulin acting as templates or 'molecular rulers', terminating exact assembly. These two giant, single-polypeptide, filamentous proteins are bound in situ along the thick and thin filaments, respectively, with an almost perfect match in the respective lengths and structural periodicities. However, evidence still questions the possibility that the proteins function as templates, or scaffolds, on which the thin and thick filaments could be assembled. In addition, the progress in muscle research during the last decades highlighted a number of other factors that could potentially be involved in the mechanism of length regulation: molecular chaperones that may guide folding and assembly of actin and myosin; capping proteins that can influence the rates of assembly-disassembly of the myofilaments; Ca2+ transients that can activate or deactivate protein interactions, etc. The entire mechanism of sarcomere assembly appears complex and highly dynamic. This mechanism is also capable of producing filaments of about the correct size without titin and nebulin. What then is the role of these proteins? Evidence points to titin and nebulin stabilizing structures of the respective filaments. This stabilizing effect, based on linear proteins of a fixed size, implies that titin and nebulin are indeed molecular rulers of the filaments. Although the proteins may not function as templates in the assembly of the filaments, they measure and stabilize exactly the same size of the functionally important for the muscles segments in each of the respective filaments.
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The effects of a skeletal muscle titin mutation on walking in mice. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2016; 203:67-76. [PMID: 27986994 DOI: 10.1007/s00359-016-1137-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Revised: 11/22/2016] [Accepted: 11/28/2016] [Indexed: 01/10/2023]
Abstract
Titin contributes to sarcomere assembly, muscle signaling, and mechanical properties of muscle. The mdm mouse exhibits a small deletion in the titin gene resulting in dystrophic mutants and phenotypically normal heterozygotes. We examined the effects of this mutation on locomotion to assess how, and if, changes to muscle phenotype explain observed locomotor differences. Mutant mice are much smaller in size than their siblings and gait abnormalities may be driven by differences in limb proportions and/or by changes to muscle phenotype caused by the titin mutation. We quantified differences in walking gait among mdm genotypes and also determined whether genotypes vary in limb morphometrics. Mice were filmed walking, and kinematic and morphological variables were measured. Mutant mice had a smaller range of motion at the ankle, shorter stride lengths, and shorter stance duration, but walked at the same relative speeds as the other genotypes. Although phenotypically similar to wildtype mice, heterozygous mice frequently exhibited intermediate gait mechanics. Morphological differences among genotypes in hindlimb proportions were small and do not explain the locomotor differences. We suggest that differences in locomotion among mdm genotypes are due to changes in muscle phenotype caused by the titin mutation.
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Crossley DA, Burggren WW, Reiber CL, Altimiras J, Rodnick KJ. Mass Transport: Circulatory System with Emphasis on Nonendothermic Species. Compr Physiol 2016; 7:17-66. [PMID: 28134997 DOI: 10.1002/cphy.c150010] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Mass transport can be generally defined as movement of material matter. The circulatory system then is a biological example given its role in the movement in transporting gases, nutrients, wastes, and chemical signals. Comparative physiology has a long history of providing new insights and advancing our understanding of circulatory mass transport across a wide array of circulatory systems. Here we focus on circulatory function of nonmodel species. Invertebrates possess diverse convection systems; that at the most complex generate pressures and perform at a level comparable to vertebrates. Many invertebrates actively modulate cardiovascular function using neuronal, neurohormonal, and skeletal muscle activity. In vertebrates, our understanding of cardiac morphology, cardiomyocyte function, and contractile protein regulation by Ca2+ highlights a high degree of conservation, but differences between species exist and are coupled to variable environments and body temperatures. Key regulators of vertebrate cardiac function and systemic blood pressure include the autonomic nervous system, hormones, and ventricular filling. Further chemical factors regulating cardiovascular function include adenosine, natriuretic peptides, arginine vasotocin, endothelin 1, bradykinin, histamine, nitric oxide, and hydrogen sulfide, to name but a few. Diverse vascular morphologies and the regulation of blood flow in the coronary and cerebral circulations are also apparent in nonmammalian species. Dynamic adjustments of cardiovascular function are associated with exercise on land, flying at high altitude, prolonged dives by marine mammals, and unique morphology, such as the giraffe. Future studies should address limits of gas exchange and convective transport, the evolution of high arterial pressure across diverse taxa, and the importance of the cardiovascular system adaptations to extreme environments. © 2017 American Physiological Society. Compr Physiol 7:17-66, 2017.
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Affiliation(s)
- Dane A Crossley
- Department of Biological Sciences, University of North Texas, Denton, Texas, USA
| | - Warren W Burggren
- Department of Biological Sciences, University of North Texas, Denton, Texas, USA
| | - Carl L Reiber
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, Nevada, USA
| | - Jordi Altimiras
- AVIAN Behavioral Genomics and Physiology, IFM Biology, Linköping University, Linköping, Sweden
| | - Kenneth J Rodnick
- Department of Biological Sciences, Idaho State University, Pocatello, Idaho, USA
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Tiffany H, Sonkar K, Gage MJ. The insertion sequence of the N2A region of titin exists in an extended structure with helical characteristics. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2016; 1865:1-10. [PMID: 27742555 DOI: 10.1016/j.bbapap.2016.10.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Revised: 10/05/2016] [Accepted: 10/07/2016] [Indexed: 12/15/2022]
Abstract
The giant sarcomere protein titin is the third filament in muscle and is integral to maintaining sarcomere integrity as well as contributing to both active and passive tension. Titin is a multi-domain protein that contains regions of repeated structural elements. The N2A region sits at the boundary between the proximal Ig region of titin that is extended under low force and the PEVK region that is extended under high force. Multiple binding interactions have been associated with the N2A region and it has been proposed that this region acts as a mechanical stretch sensor. The focus of this work is a 117 amino acid portion of the N2A region (N2A-IS), which resides between the proximal Ig domains and the PEVK region. Our work has shown that the N2A-IS region is predicted to contain helical structure in the center while both termini are predicted to be disordered. Recombinantly expressed N2A-IS protein contains 13% α-helical structure, as measured via circular dichroism. Additional α-helical structure can be induced with 2,2,2-trifluoroethanol, suggesting that there is transient helical structure that might be stabilized in the context of the entire N2A region. The N2A-IS region does not exhibit any cooperativity in either thermal or chemical denaturation studies while size exclusion chromatography and Fluorescence Resonance Energy Transfer demonstrates that the N2A-IS region has an extended structure. Combined, these results lead to a model of the N2A-IS region having a helical core with extended N- and C-termini.
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Affiliation(s)
- Holly Tiffany
- Department of Biology, Northern Arizona University, Flagstaff, AZ, United States
| | - Kanchan Sonkar
- Department of Chemistry and Biochemistry, Northern Arizona University, Flagstaff, AZ, United States
| | - Matthew J Gage
- Department of Chemistry and Biochemistry, Northern Arizona University, Flagstaff, AZ, United States; Center for Bioengineering Innovation, Northern Arizona University, Flagstaff, AZ, United States; Department of Chemistry, University of Massachusetts Lowell, Lowell, MA, United States.
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Khan MAF, Reckman YJ, Aufiero S, van den Hoogenhof MMG, van der Made I, Beqqali A, Koolbergen DR, Rasmussen TB, van der Velden J, Creemers EE, Pinto YM. RBM20 Regulates Circular RNA Production From the Titin Gene. Circ Res 2016; 119:996-1003. [PMID: 27531932 DOI: 10.1161/circresaha.116.309568] [Citation(s) in RCA: 208] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/14/2016] [Accepted: 08/14/2016] [Indexed: 11/16/2022]
Abstract
RATIONALE RNA-binding motif protein 20 (RBM20) is essential for normal splicing of many cardiac genes, and loss of RBM20 causes dilated cardiomyopathy. Given its role in splicing, we hypothesized an important role for RBM20 in forming circular RNAs (circRNAs), a novel class of noncoding RNA molecules. OBJECTIVE To establish the role of RBM20 in the formation of circRNAs in the heart. METHODS AND RESULTS Here, we performed circRNA profiling on ribosomal depleted RNA from human hearts and identified the expression of thousands of circRNAs, with some of them regulated in disease. Interestingly, we identified 80 circRNAs to be expressed from the titin gene, a gene that is known to undergo highly complex alternative splicing. We show that some of these circRNAs are dynamically regulated in dilated cardiomyopathy but not in hypertrophic cardiomyopathy. We generated RBM20-null mice and show that they completely lack these titin circRNAs. In addition, in a cardiac sample from an RBM20 mutation carrier, titin circRNA production was severely altered. Interestingly, the loss of RBM20 caused only a specific subset of titin circRNAs to be lost. These circRNAs originated from the RBM20-regulated I-band region of the titin transcript. CONCLUSIONS We show that RBM20 is crucial for the formation of a subset of circRNAs that originate from the I-band of the titin gene. We propose that RBM20, by excluding specific exons from the pre-mRNA, provides the substrate to form this class of RBM20-dependent circRNAs.
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Affiliation(s)
- Mohsin A F Khan
- From the Department of Experimental Cardiology (M.A.F.K., Y.J.R., S.A., M.M.G.v.d.H., I.v.d.M., A.B., E.E.C., Y.M.P.), Department of Clinical Epidemiology, Biostatistics and Bioinformatics (M.A.F.K., S.A.), and Department of Cardiothoracic Surgery (D.R.K.), Academic Medical Center, Amsterdam, The Netherlands; Department of Cardiology, Aarhus University Hospital, Denmark (T.B.R.); and Department of Physiology, VU University Medical Center, Amsterdam, The Netherlands (J.v.d.V.)
| | - Yolan J Reckman
- From the Department of Experimental Cardiology (M.A.F.K., Y.J.R., S.A., M.M.G.v.d.H., I.v.d.M., A.B., E.E.C., Y.M.P.), Department of Clinical Epidemiology, Biostatistics and Bioinformatics (M.A.F.K., S.A.), and Department of Cardiothoracic Surgery (D.R.K.), Academic Medical Center, Amsterdam, The Netherlands; Department of Cardiology, Aarhus University Hospital, Denmark (T.B.R.); and Department of Physiology, VU University Medical Center, Amsterdam, The Netherlands (J.v.d.V.)
| | - Simona Aufiero
- From the Department of Experimental Cardiology (M.A.F.K., Y.J.R., S.A., M.M.G.v.d.H., I.v.d.M., A.B., E.E.C., Y.M.P.), Department of Clinical Epidemiology, Biostatistics and Bioinformatics (M.A.F.K., S.A.), and Department of Cardiothoracic Surgery (D.R.K.), Academic Medical Center, Amsterdam, The Netherlands; Department of Cardiology, Aarhus University Hospital, Denmark (T.B.R.); and Department of Physiology, VU University Medical Center, Amsterdam, The Netherlands (J.v.d.V.)
| | - Maarten M G van den Hoogenhof
- From the Department of Experimental Cardiology (M.A.F.K., Y.J.R., S.A., M.M.G.v.d.H., I.v.d.M., A.B., E.E.C., Y.M.P.), Department of Clinical Epidemiology, Biostatistics and Bioinformatics (M.A.F.K., S.A.), and Department of Cardiothoracic Surgery (D.R.K.), Academic Medical Center, Amsterdam, The Netherlands; Department of Cardiology, Aarhus University Hospital, Denmark (T.B.R.); and Department of Physiology, VU University Medical Center, Amsterdam, The Netherlands (J.v.d.V.)
| | - Ingeborg van der Made
- From the Department of Experimental Cardiology (M.A.F.K., Y.J.R., S.A., M.M.G.v.d.H., I.v.d.M., A.B., E.E.C., Y.M.P.), Department of Clinical Epidemiology, Biostatistics and Bioinformatics (M.A.F.K., S.A.), and Department of Cardiothoracic Surgery (D.R.K.), Academic Medical Center, Amsterdam, The Netherlands; Department of Cardiology, Aarhus University Hospital, Denmark (T.B.R.); and Department of Physiology, VU University Medical Center, Amsterdam, The Netherlands (J.v.d.V.)
| | - Abdelaziz Beqqali
- From the Department of Experimental Cardiology (M.A.F.K., Y.J.R., S.A., M.M.G.v.d.H., I.v.d.M., A.B., E.E.C., Y.M.P.), Department of Clinical Epidemiology, Biostatistics and Bioinformatics (M.A.F.K., S.A.), and Department of Cardiothoracic Surgery (D.R.K.), Academic Medical Center, Amsterdam, The Netherlands; Department of Cardiology, Aarhus University Hospital, Denmark (T.B.R.); and Department of Physiology, VU University Medical Center, Amsterdam, The Netherlands (J.v.d.V.)
| | - Dave R Koolbergen
- From the Department of Experimental Cardiology (M.A.F.K., Y.J.R., S.A., M.M.G.v.d.H., I.v.d.M., A.B., E.E.C., Y.M.P.), Department of Clinical Epidemiology, Biostatistics and Bioinformatics (M.A.F.K., S.A.), and Department of Cardiothoracic Surgery (D.R.K.), Academic Medical Center, Amsterdam, The Netherlands; Department of Cardiology, Aarhus University Hospital, Denmark (T.B.R.); and Department of Physiology, VU University Medical Center, Amsterdam, The Netherlands (J.v.d.V.)
| | - Torsten B Rasmussen
- From the Department of Experimental Cardiology (M.A.F.K., Y.J.R., S.A., M.M.G.v.d.H., I.v.d.M., A.B., E.E.C., Y.M.P.), Department of Clinical Epidemiology, Biostatistics and Bioinformatics (M.A.F.K., S.A.), and Department of Cardiothoracic Surgery (D.R.K.), Academic Medical Center, Amsterdam, The Netherlands; Department of Cardiology, Aarhus University Hospital, Denmark (T.B.R.); and Department of Physiology, VU University Medical Center, Amsterdam, The Netherlands (J.v.d.V.)
| | - Jolanda van der Velden
- From the Department of Experimental Cardiology (M.A.F.K., Y.J.R., S.A., M.M.G.v.d.H., I.v.d.M., A.B., E.E.C., Y.M.P.), Department of Clinical Epidemiology, Biostatistics and Bioinformatics (M.A.F.K., S.A.), and Department of Cardiothoracic Surgery (D.R.K.), Academic Medical Center, Amsterdam, The Netherlands; Department of Cardiology, Aarhus University Hospital, Denmark (T.B.R.); and Department of Physiology, VU University Medical Center, Amsterdam, The Netherlands (J.v.d.V.)
| | - Esther E Creemers
- From the Department of Experimental Cardiology (M.A.F.K., Y.J.R., S.A., M.M.G.v.d.H., I.v.d.M., A.B., E.E.C., Y.M.P.), Department of Clinical Epidemiology, Biostatistics and Bioinformatics (M.A.F.K., S.A.), and Department of Cardiothoracic Surgery (D.R.K.), Academic Medical Center, Amsterdam, The Netherlands; Department of Cardiology, Aarhus University Hospital, Denmark (T.B.R.); and Department of Physiology, VU University Medical Center, Amsterdam, The Netherlands (J.v.d.V.).
| | - Yigal M Pinto
- From the Department of Experimental Cardiology (M.A.F.K., Y.J.R., S.A., M.M.G.v.d.H., I.v.d.M., A.B., E.E.C., Y.M.P.), Department of Clinical Epidemiology, Biostatistics and Bioinformatics (M.A.F.K., S.A.), and Department of Cardiothoracic Surgery (D.R.K.), Academic Medical Center, Amsterdam, The Netherlands; Department of Cardiology, Aarhus University Hospital, Denmark (T.B.R.); and Department of Physiology, VU University Medical Center, Amsterdam, The Netherlands (J.v.d.V.).
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47
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Shimizu I, Minamino T. Physiological and pathological cardiac hypertrophy. J Mol Cell Cardiol 2016; 97:245-62. [PMID: 27262674 DOI: 10.1016/j.yjmcc.2016.06.001] [Citation(s) in RCA: 609] [Impact Index Per Article: 76.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/29/2015] [Revised: 05/10/2016] [Accepted: 06/01/2016] [Indexed: 12/24/2022]
Abstract
The heart must continuously pump blood to supply the body with oxygen and nutrients. To maintain the high energy consumption required by this role, the heart is equipped with multiple complex biological systems that allow adaptation to changes of systemic demand. The processes of growth (hypertrophy), angiogenesis, and metabolic plasticity are critically involved in maintenance of cardiac homeostasis. Cardiac hypertrophy is classified as physiological when it is associated with normal cardiac function or as pathological when associated with cardiac dysfunction. Physiological hypertrophy of the heart occurs in response to normal growth of children or during pregnancy, as well as in athletes. In contrast, pathological hypertrophy is induced by factors such as prolonged and abnormal hemodynamic stress, due to hypertension, myocardial infarction etc. Pathological hypertrophy is associated with fibrosis, capillary rarefaction, increased production of pro-inflammatory cytokines, and cellular dysfunction (impairment of signaling, suppression of autophagy, and abnormal cardiomyocyte/non-cardiomyocyte interactions), as well as undesirable epigenetic changes, with these complex responses leading to maladaptive cardiac remodeling and heart failure. This review describes the key molecules and cellular responses involved in physiological/pathological cardiac hypertrophy.
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Affiliation(s)
- Ippei Shimizu
- Department of Cardiovascular Biology and Medicine, Niigata University Graduate School of Medical and Dental Sciences, Niigata 951-8510, Japan; Division of Molecular Aging and Cell Biology, Niigata University Graduate School of Medical and Dental Sciences, Niigata 951-8510, Japan.
| | - Tohru Minamino
- Department of Cardiovascular Biology and Medicine, Niigata University Graduate School of Medical and Dental Sciences, Niigata 951-8510, Japan.
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Bianco P, Mártonfalvi Z, Naftz K, Kőszegi D, Kellermayer M. Titin domains progressively unfolded by force are homogenously distributed along the molecule. Biophys J 2016. [PMID: 26200869 DOI: 10.1016/j.bpj.2015.06.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Titin is a giant filamentous protein of the muscle sarcomere in which stretch induces the unfolding of its globular domains. However, the mechanisms of how domains are progressively selected for unfolding and which domains eventually unfold have for long been elusive. Based on force-clamp optical tweezers experiments we report here that, in a paradoxical violation of mechanically driven activation kinetics, neither the global domain unfolding rate, nor the folded-state lifetime distributions of full-length titin are sensitive to force. This paradox is reconciled by a gradient of mechanical stability so that domains are gradually selected for unfolding as the magnitude of the force field increases. Atomic force microscopic screening of extended titin molecules revealed that the unfolded domains are distributed homogenously along the entire length of titin, and this homogeneity is maintained with increasing overstretch. Although the unfolding of domains with progressively increasing mechanical stability makes titin a variable viscosity damper, the spatially randomized variation of domain stability ensures that the induced structural changes are not localized but are distributed along the molecule's length. Titin may thereby provide complex safety mechanims for protecting the sarcomere against structural disintegration under excessive mechanical conditions.
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Affiliation(s)
- Pasquale Bianco
- Department of Biophysics and Radiation Biology, Semmelweis University, Budapest, Hungary
| | - Zsolt Mártonfalvi
- Department of Biophysics and Radiation Biology, Semmelweis University, Budapest, Hungary
| | - Katalin Naftz
- Department of Biophysics and Radiation Biology, Semmelweis University, Budapest, Hungary
| | - Dorina Kőszegi
- Department of Biophysics and Radiation Biology, Semmelweis University, Budapest, Hungary
| | - Miklós Kellermayer
- Department of Biophysics and Radiation Biology, Semmelweis University, Budapest, Hungary; MTA-SE Molecular Biophysics Research Group, Semmelweis University, Budapest, Hungary.
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Lindstedt SL. Skeletal muscle tissue in movement and health: positives and negatives. J Exp Biol 2016; 219:183-8. [DOI: 10.1242/jeb.124297] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
ABSTRACT
The history of muscle physiology is a wonderful lesson in ‘the scientific method’; our functional hypotheses have been limited by our ability to decipher (observe) muscle structure. The simplistic understanding of how muscles work made a large leap with the remarkable insights of A. V. Hill, who related muscle force and power to shortening velocity and energy use. However, Hill's perspective was largely limited to isometric and isotonic contractions founded on isolated muscle properties that do not always reflect how muscles function in vivo. Robert Josephson incorporated lengthening contractions into a work loop analysis that shifted the focus to dynamic muscle function, varying force, length and work done both by and on muscle during a single muscle work cycle. It became apparent that muscle is both a force generator and a spring. Titin, the missing filament in the sliding filament model, is a muscle spring, which functions very differently in cardiac versus skeletal muscle; its possible role in these two muscle types is discussed relative to their contrasting function. The good news for those of us who choose to work on skeletal muscle is that muscle has been reluctant to reveal all of its secrets.
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Affiliation(s)
- Stan L. Lindstedt
- Northern Arizona University, Department of Biological Sciences andCenter for Bioengineering Innovation, Flagstaff, AZ 86011-4165, USA
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50
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Lyon RC, Zanella F, Omens JH, Sheikh F. Mechanotransduction in cardiac hypertrophy and failure. Circ Res 2015; 116:1462-1476. [PMID: 25858069 PMCID: PMC4394185 DOI: 10.1161/circresaha.116.304937] [Citation(s) in RCA: 218] [Impact Index Per Article: 24.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/23/2015] [Accepted: 03/13/2015] [Indexed: 01/10/2023]
Abstract
Cardiac muscle cells have an intrinsic ability to sense and respond to mechanical load through a process known as mechanotransduction. In the heart, this process involves the conversion of mechanical stimuli into biochemical events that induce changes in myocardial structure and function. Mechanotransduction and its downstream effects function initially as adaptive responses that serve as compensatory mechanisms during adaptation to the initial load. However, under prolonged and abnormal loading conditions, the remodeling processes can become maladaptive, leading to altered physiological function and the development of pathological cardiac hypertrophy and heart failure. Although the mechanisms underlying mechanotransduction are far from being fully elucidated, human and mouse genetic studies have highlighted various cytoskeletal and sarcolemmal structures in cardiac myocytes as the likely candidates for load transducers, based on their link to signaling molecules and architectural components important in disease pathogenesis. In this review, we summarize recent developments that have uncovered specific protein complexes linked to mechanotransduction and mechanotransmission within the sarcomere, the intercalated disc, and at the sarcolemma. The protein structures acting as mechanotransducers are the first step in the process that drives physiological and pathological cardiac hypertrophy and remodeling, as well as the transition to heart failure, and may provide better insights into mechanisms driving mechanotransduction-based diseases.
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Affiliation(s)
- Robert C. Lyon
- Department of Medicine, University of California San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA
| | - Fabian Zanella
- Department of Medicine, University of California San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA
| | - Jeffrey H. Omens
- Department of Medicine, University of California San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA
- Department of Bioengineering, University of California San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA
| | - Farah Sheikh
- Department of Medicine, University of California San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA
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