1
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Best AJ, Braunschweig U, Wu M, Farhangmehr S, Pasculescu A, Lim JJ, Comsa LC, Jen M, Wang J, Datti A, Wrana JL, Cordes SP, Al-Awar R, Han H, Blencowe BJ. High-throughput sensitive screening of small molecule modulators of microexon alternative splicing using dual Nano and Firefly luciferase reporters. Nat Commun 2024; 15:6328. [PMID: 39068192 PMCID: PMC11283458 DOI: 10.1038/s41467-024-50399-6] [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: 03/18/2023] [Accepted: 07/03/2024] [Indexed: 07/30/2024] Open
Abstract
Disruption of alternative splicing frequently causes or contributes to human diseases and disorders. Consequently, there is a need for efficient and sensitive reporter assays capable of screening chemical libraries for compounds with efficacy in modulating important splicing events. Here, we describe a screening workflow employing dual Nano and Firefly luciferase alternative splicing reporters that affords efficient, sensitive, and linear detection of small molecule responses. Applying this system to a screen of ~95,000 small molecules identified compounds that stimulate or repress the splicing of neuronal microexons, a class of alternative exons often disrupted in autism and activated in neuroendocrine cancers. One of these compounds rescues the splicing of several analyzed microexons in the cerebral cortex of an autism mouse model haploinsufficient for Srrm4, a major activator of brain microexons. We thus describe a broadly applicable high-throughput screening system for identifying candidate splicing therapeutics, and a resource of small molecule modulators of microexons with potential for further development in correcting aberrant splicing patterns linked to human disorders and disease.
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Affiliation(s)
- Andrew J Best
- Donnelly Centre, University of Toronto, Toronto, ON, Canada.
| | | | - Mingkun Wu
- Donnelly Centre, University of Toronto, Toronto, ON, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Shaghayegh Farhangmehr
- Donnelly Centre, University of Toronto, Toronto, ON, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Adrian Pasculescu
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, ON, Canada
| | - Justin J Lim
- Donnelly Centre, University of Toronto, Toronto, ON, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Lim Caden Comsa
- Donnelly Centre, University of Toronto, Toronto, ON, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Mark Jen
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, ON, Canada
| | - Jenny Wang
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, ON, Canada
| | - Alessandro Datti
- Department of Agricultural, Food, and Environmental Sciences, University of Perugia, Perugia, Italy
| | - Jeffrey L Wrana
- Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, ON, Canada
| | - Sabine P Cordes
- Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, ON, Canada
| | - Rima Al-Awar
- Department of Pharmacology and Toxicology, University of Toronto, Toronto, ON, Canada
| | - Hong Han
- Donnelly Centre, University of Toronto, Toronto, ON, Canada
| | - Benjamin J Blencowe
- Donnelly Centre, University of Toronto, Toronto, ON, Canada.
- Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada.
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2
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Fender J, Klöcker J, Boivin-Jahns V, Ravens U, Jahns R, Lorenz K. "Cardiac glycosides"-quo vaditis?-past, present, and future? NAUNYN-SCHMIEDEBERG'S ARCHIVES OF PHARMACOLOGY 2024:10.1007/s00210-024-03285-3. [PMID: 39007928 DOI: 10.1007/s00210-024-03285-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2024] [Accepted: 07/03/2024] [Indexed: 07/16/2024]
Abstract
Up to date, digitalis glycosides, also known as "cardiac glycosides", are inhibitors of the Na+/K+-ATPase. They have a long-standing history as drugs used in patients suffering from heart failure and atrial fibrillation despite their well-known narrow therapeutic range and the intensive discussions on their raison d'être for these indications. This article will review the history and key findings in basic and clinical research as well as potentially overseen pros and cons of these drugs.
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Affiliation(s)
- Julia Fender
- Institute of Pharmacology and Toxicology, University of Würzburg, Versbacher Straße 9, 97078, Würzburg, Germany
| | - Johanna Klöcker
- Institute of Pharmacology and Toxicology, University of Würzburg, Versbacher Straße 9, 97078, Würzburg, Germany
| | - Valérie Boivin-Jahns
- Institute of Pharmacology and Toxicology, University of Würzburg, Versbacher Straße 9, 97078, Würzburg, Germany
| | - Ursula Ravens
- Institute of Experimental Cardiovascular Medicine, Faculty of Medicine, University of Freiburg, Elsässer Straße 2Q, 79110, Freiburg, Germany
| | - Roland Jahns
- Interdisciplinary Bank of Biological Materials and Data Würzburg (ibdw), University Hospital Würzburg, Straubmühlweg 2a, 97078, Würzburg, Germany
| | - Kristina Lorenz
- Institute of Pharmacology and Toxicology, University of Würzburg, Versbacher Straße 9, 97078, Würzburg, Germany.
- Leibniz-Institut für Analytische Wissenschaften-ISAS e.V., Bunsen-Kirchhoff-Straße 11, 44139, Dortmund, Germany.
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3
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林 欣. [Research progress on the expression of the RBM20 gene in dilated cardiomyopathy]. ZHONGGUO DANG DAI ER KE ZA ZHI = CHINESE JOURNAL OF CONTEMPORARY PEDIATRICS 2023; 25:1084-1088. [PMID: 37905768 PMCID: PMC10621058 DOI: 10.7499/j.issn.1008-8830.2306087] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Accepted: 08/31/2023] [Indexed: 11/02/2023]
Abstract
Dilated cardiomyopathy (DCM) is a significant contributor to heart failure and can lead to life-threatening cardiovascular events at any stage. RNA-binding motif protein 20 (RBM20) gene mutation is known to be one of the causes of DCM. This mutation exhibits familial aggregation and is associated with arrhythmias, increasing the risk of sudden and early death. This article delves into the characteristics of the RBM20 gene, highlighting its role in regulating alternative splicing of the TTN gene and calcium/calmodulin-dependent protein kinase type II gene. Furthermore, the article provides a summary of treatment options available for DCM caused by RBM20 gene mutations, aiming to enhance clinicians' understanding of the RBM20 gene and provide new ideas for precision medicine treatment.
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4
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Gotthardt M, Badillo-Lisakowski V, Parikh VN, Ashley E, Furtado M, Carmo-Fonseca M, Schudy S, Meder B, Grosch M, Steinmetz L, Crocini C, Leinwand L. Cardiac splicing as a diagnostic and therapeutic target. Nat Rev Cardiol 2023; 20:517-530. [PMID: 36653465 DOI: 10.1038/s41569-022-00828-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 12/09/2022] [Indexed: 01/19/2023]
Abstract
Despite advances in therapeutics for heart failure and arrhythmias, a substantial proportion of patients with cardiomyopathy do not respond to interventions, indicating a need to identify novel modifiable myocardial pathobiology. Human genetic variation associated with severe forms of cardiomyopathy and arrhythmias has highlighted the crucial role of alternative splicing in myocardial health and disease, given that it determines which mature RNA transcripts drive the mechanical, structural, signalling and metabolic properties of the heart. In this Review, we discuss how the analysis of cardiac isoform expression has been facilitated by technical advances in multiomics and long-read and single-cell sequencing technologies. The resulting insights into the regulation of alternative splicing - including the identification of cardiac splice regulators as therapeutic targets and the development of a translational pipeline to evaluate splice modulators in human engineered heart tissue, animal models and clinical trials - provide a basis for improved diagnosis and therapy. Finally, we consider how the medical and scientific communities can benefit from facilitated acquisition and interpretation of splicing data towards improved clinical decision-making and patient care.
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Affiliation(s)
- Michael Gotthardt
- Neuromuscular and Cardiovascular Cell Biology, Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany.
- DZHK (German Center for Cardiovascular Research Partner Site Berlin), Berlin, Germany.
- Department of Cardiology, Charité - Universitätsmedizin Berlin, Berlin, Germany.
| | - Victor Badillo-Lisakowski
- Neuromuscular and Cardiovascular Cell Biology, Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany
- DZHK (German Center for Cardiovascular Research Partner Site Berlin), Berlin, Germany
| | - Victoria Nicole Parikh
- Stanford Center for Inherited Cardiovascular Disease, Stanford University School of Medicine, Palo Alto, CA, USA
| | - Euan Ashley
- Stanford Center for Inherited Cardiovascular Disease, Stanford University School of Medicine, Palo Alto, CA, USA
- Stanford Genome Technology Center, Stanford University, Palo Alto, CA, USA
- Department of Genetics, School of Medicine, Stanford University, Stanford, CA, USA
| | - Marta Furtado
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
| | - Maria Carmo-Fonseca
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
| | - Sarah Schudy
- Institute for Cardiomyopathies, Department of Medicine III, University of Heidelberg, Heidelberg, Germany
| | - Benjamin Meder
- Institute for Cardiomyopathies, Department of Medicine III, University of Heidelberg, Heidelberg, Germany
- DZHK (German Center for Cardiovascular Research Partner Site Heidelberg-Mannheim), Heidelberg, Germany
| | - Markus Grosch
- European Molecular Biology Laboratory (EMBL), Genome Biology Unit, Heidelberg, Germany
| | - Lars Steinmetz
- Stanford Genome Technology Center, Stanford University, Palo Alto, CA, USA
- Department of Genetics, School of Medicine, Stanford University, Stanford, CA, USA
- European Molecular Biology Laboratory (EMBL), Genome Biology Unit, Heidelberg, Germany
| | - Claudia Crocini
- Department of Molecular, Cellular, and Developmental Biology and BioFrontiers Institute, University of Colorado, Boulder, CO, USA
| | - Leslie Leinwand
- Department of Molecular, Cellular, and Developmental Biology and BioFrontiers Institute, University of Colorado, Boulder, CO, USA
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5
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Shi X, Won M, Tang C, Ding Q, Sharma A, Wang F, Kim JS. RNA splicing based on reporter genes system: Detection, imaging and applications. Coord Chem Rev 2023. [DOI: 10.1016/j.ccr.2022.214929] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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6
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Li N, Hang W, Shu H, Zhou N. RBM20, a Therapeutic Target to Alleviate Myocardial Stiffness via Titin Isoforms Switching in HFpEF. Front Cardiovasc Med 2022; 9:928244. [PMID: 35783855 PMCID: PMC9243441 DOI: 10.3389/fcvm.2022.928244] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Accepted: 05/30/2022] [Indexed: 12/05/2022] Open
Abstract
Increased myocardial stiffness is critically involved in heart diseases with impaired cardiac compliance, especially heart failure with preserved ejection fraction (HFpEF). Myocardial stiffness mainly derives from cardiomyocyte- and extracellular matrix (ECM)-derived passive stiffness. Titin, a major component of sarcomeres, participates in myocardial passive stiffness and stress-sensitive signaling. The ratio of two titin isoforms, N2BA to N2B, was validated to influence diastolic dysfunction via several pathways. RNA binding motif protein 20 (RBM20) is a well-studied splicing factor of titin, functional deficiency of RBM20 in mice profile improved cardiac compliance and function, which indicated that RBM20 functions as a potential therapeutic target for mitigating myocardial stiffness by modulating titin isoforms. This minor review summarized how RBM20 and other splicing factors modify the titin isoforms ratio, therefore providing a promising target for improving the myocardial compliance of HFpEF.
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7
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Lin YH, Major JL, Liebner T, Hourani Z, Travers JG, Wennersten SA, Haefner KR, Cavasin MA, Wilson CE, Jeong MY, Han Y, Gotthardt M, Ferguson SK, Ambardekar AV, Lam MP, Choudhary C, Granzier HL, Woulfe KC, McKinsey TA. HDAC6 modulates myofibril stiffness and diastolic function of the heart. J Clin Invest 2022; 132:e148333. [PMID: 35575093 PMCID: PMC9106344 DOI: 10.1172/jci148333] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Accepted: 04/05/2022] [Indexed: 01/26/2023] Open
Abstract
Passive stiffness of the heart is determined largely by extracellular matrix and titin, which functions as a molecular spring within sarcomeres. Titin stiffening is associated with the development of diastolic dysfunction (DD), while augmented titin compliance appears to impair systolic performance in dilated cardiomyopathy. We found that myofibril stiffness was elevated in mice lacking histone deacetylase 6 (HDAC6). Cultured adult murine ventricular myocytes treated with a selective HDAC6 inhibitor also exhibited increased myofibril stiffness. Conversely, HDAC6 overexpression in cardiomyocytes led to decreased myofibril stiffness, as did ex vivo treatment of mouse, rat, and human myofibrils with recombinant HDAC6. Modulation of myofibril stiffness by HDAC6 was dependent on 282 amino acids encompassing a portion of the PEVK element of titin. HDAC6 colocalized with Z-disks, and proteomics analysis suggested that HDAC6 functions as a sarcomeric protein deacetylase. Finally, increased myofibril stiffness in HDAC6-deficient mice was associated with exacerbated DD in response to hypertension or aging. These findings define a role for a deacetylase in the control of myofibril function and myocardial passive stiffness, suggest that reversible acetylation alters titin compliance, and reveal the potential of targeting HDAC6 to manipulate the elastic properties of the heart to treat cardiac diseases.
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Affiliation(s)
- Ying-Hsi Lin
- Department of Medicine, Division of Cardiology, and
- Consortium for Fibrosis Research & Translation, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Jennifer L. Major
- Department of Medicine, Division of Cardiology, and
- Consortium for Fibrosis Research & Translation, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Tim Liebner
- Department of Proteomics, Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Zaynab Hourani
- Department of Cellular and Molecular Medicine and Sarver Molecular Cardiovascular Research Program, University of Arizona, Tucson, Arizona, USA
| | - Joshua G. Travers
- Department of Medicine, Division of Cardiology, and
- Consortium for Fibrosis Research & Translation, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Sara A. Wennersten
- Department of Medicine, Division of Cardiology, and
- Consortium for Fibrosis Research & Translation, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Korey R. Haefner
- Department of Medicine, Division of Cardiology, and
- Consortium for Fibrosis Research & Translation, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Maria A. Cavasin
- Department of Medicine, Division of Cardiology, and
- Consortium for Fibrosis Research & Translation, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | | | | | - Yu Han
- Department of Medicine, Division of Cardiology, and
- Consortium for Fibrosis Research & Translation, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Michael Gotthardt
- Neuromuscular and Cardiovascular Cell Biology, Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany
- Charité–Universitätsmedizin Berlin, Berlin, Germany
| | - Scott K. Ferguson
- Cardiovascular and Pulmonary Research Laboratory, Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Amrut V. Ambardekar
- Department of Medicine, Division of Cardiology, and
- Consortium for Fibrosis Research & Translation, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Maggie P.Y. Lam
- Department of Medicine, Division of Cardiology, and
- Consortium for Fibrosis Research & Translation, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Chunaram Choudhary
- Department of Proteomics, Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Henk L. Granzier
- Department of Cellular and Molecular Medicine and Sarver Molecular Cardiovascular Research Program, University of Arizona, Tucson, Arizona, USA
| | | | - Timothy A. McKinsey
- Department of Medicine, Division of Cardiology, and
- Consortium for Fibrosis Research & Translation, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
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8
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Radke MH, Badillo-Lisakowski V, Britto-Borges T, Kubli DA, Jüttner R, Parakkat P, Carballo JL, Hüttemeister J, Liss M, Hansen A, Dieterich C, Mullick AE, Gotthardt M. Therapeutic inhibition of RBM20 improves diastolic function in a murine heart failure model and human engineered heart tissue. Sci Transl Med 2021; 13:eabe8952. [PMID: 34851694 DOI: 10.1126/scitranslmed.abe8952] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
[Figure: see text].
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Affiliation(s)
- Michael H Radke
- Department of Neuromuscular and Cardiovascular Cell Biology, Max Delbrück Center for Molecular Medicine in the Helmholtz Association, 13125 Berlin, Germany.,German Center for Cardiovascular Research (DZHK), partner site Berlin, 10785 Berlin, Germany
| | - Victor Badillo-Lisakowski
- Department of Neuromuscular and Cardiovascular Cell Biology, Max Delbrück Center for Molecular Medicine in the Helmholtz Association, 13125 Berlin, Germany.,German Center for Cardiovascular Research (DZHK), partner site Berlin, 10785 Berlin, Germany.,Humboldt-Universität zu Berlin, 10099 Berlin, Germany
| | - Thiago Britto-Borges
- Section of Bioinformatics and Systems Cardiology, Klaus Tschira Institute for Integrative Computational Cardiology and Department of Internal Medicine III, University Hospital Heidelberg, 69120 Heidelberg, Germany.,German Center for Cardiovascular Research (DZHK), partner site Heidelberg/Mannheim, 69120 Heidelberg, Germany
| | | | - René Jüttner
- Department of Neuromuscular and Cardiovascular Cell Biology, Max Delbrück Center for Molecular Medicine in the Helmholtz Association, 13125 Berlin, Germany
| | - Pragati Parakkat
- Department of Neuromuscular and Cardiovascular Cell Biology, Max Delbrück Center for Molecular Medicine in the Helmholtz Association, 13125 Berlin, Germany.,German Center for Cardiovascular Research (DZHK), partner site Berlin, 10785 Berlin, Germany.,Department of Cardiology, Charité Universitätsmedizin Berlin, 10115 Berlin, Germany
| | - Jacobo Lopez Carballo
- Department of Neuromuscular and Cardiovascular Cell Biology, Max Delbrück Center for Molecular Medicine in the Helmholtz Association, 13125 Berlin, Germany.,Department of Cardiology, Charité Universitätsmedizin Berlin, 10115 Berlin, Germany
| | - Judith Hüttemeister
- Department of Neuromuscular and Cardiovascular Cell Biology, Max Delbrück Center for Molecular Medicine in the Helmholtz Association, 13125 Berlin, Germany.,German Center for Cardiovascular Research (DZHK), partner site Berlin, 10785 Berlin, Germany
| | - Martin Liss
- Department of Neuromuscular and Cardiovascular Cell Biology, Max Delbrück Center for Molecular Medicine in the Helmholtz Association, 13125 Berlin, Germany.,German Center for Cardiovascular Research (DZHK), partner site Berlin, 10785 Berlin, Germany
| | - Arne Hansen
- Department of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany.,German Center for Cardiovascular Research (DZHK), partner site Hamburg/Kiel/Lübeck, 20246 Hamburg, Germany
| | - Christoph Dieterich
- Section of Bioinformatics and Systems Cardiology, Klaus Tschira Institute for Integrative Computational Cardiology and Department of Internal Medicine III, University Hospital Heidelberg, 69120 Heidelberg, Germany.,German Center for Cardiovascular Research (DZHK), partner site Heidelberg/Mannheim, 69120 Heidelberg, Germany
| | | | - Michael Gotthardt
- Department of Neuromuscular and Cardiovascular Cell Biology, Max Delbrück Center for Molecular Medicine in the Helmholtz Association, 13125 Berlin, Germany.,German Center for Cardiovascular Research (DZHK), partner site Berlin, 10785 Berlin, Germany.,Department of Cardiology, Charité Universitätsmedizin Berlin, 10115 Berlin, Germany
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9
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van der Pijl RJ, Domenighetti AA, Sheikh F, Ehler E, Ottenheijm CAC, Lange S. The titin N2B and N2A regions: biomechanical and metabolic signaling hubs in cross-striated muscles. Biophys Rev 2021; 13:653-677. [PMID: 34745373 PMCID: PMC8553726 DOI: 10.1007/s12551-021-00836-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Accepted: 08/23/2021] [Indexed: 02/07/2023] Open
Abstract
Muscle specific signaling has been shown to originate from myofilaments and their associated cellular structures, including the sarcomeres, costameres or the cardiac intercalated disc. Two signaling hubs that play important biomechanical roles for cardiac and/or skeletal muscle physiology are the N2B and N2A regions in the giant protein titin. Prominent proteins associated with these regions in titin are chaperones Hsp90 and αB-crystallin, members of the four-and-a-half LIM (FHL) and muscle ankyrin repeat protein (Ankrd) families, as well as thin filament-associated proteins, such as myopalladin. This review highlights biological roles and properties of the titin N2B and N2A regions in health and disease. Special emphasis is placed on functions of Ankrd and FHL proteins as mechanosensors that modulate muscle-specific signaling and muscle growth. This region of the sarcomere also emerged as a hotspot for the modulation of passive muscle mechanics through altered titin phosphorylation and splicing, as well as tethering mechanisms that link titin to the thin filament system.
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Affiliation(s)
| | - Andrea A. Domenighetti
- Shirley Ryan AbilityLab, Chicago, IL USA
- Department of Physical Medicine and Rehabilitation, Northwestern University, Chicago, IL USA
| | - Farah Sheikh
- Division of Cardiology, School of Medicine, UC San Diego, La Jolla, CA USA
| | - Elisabeth Ehler
- Randall Centre for Cell and Molecular Biophysics, School of Cardiovascular Medicine and Sciences, King’s College London, London, UK
| | - Coen A. C. Ottenheijm
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ USA
- Department of Physiology, Amsterdam University Medical Centers, Amsterdam, The Netherlands
| | - Stephan Lange
- Division of Cardiology, School of Medicine, UC San Diego, La Jolla, CA USA
- Department of Molecular and Clinical Medicine, University of Gothenburg, Gothenburg, Sweden
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10
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Loescher CM, Hobbach AJ, Linke WA. Titin (TTN): from molecule to modifications, mechanics and medical significance. Cardiovasc Res 2021; 118:2903-2918. [PMID: 34662387 PMCID: PMC9648829 DOI: 10.1093/cvr/cvab328] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Accepted: 10/13/2021] [Indexed: 12/19/2022] Open
Abstract
The giant sarcomere protein titin is a major determinant of cardiomyocyte stiffness and contributor to cardiac strain sensing. Titin-based forces are highly regulated in health and disease, which aids in the regulation of myocardial function, including cardiac filling and output. Due to the enormous size, complexity, and malleability of the titin molecule, titin properties are also vulnerable to dysregulation, as observed in various cardiac disorders. This review provides an overview of how cardiac titin properties can be changed at a molecular level, including the role isoform diversity and post-translational modifications (acetylation, oxidation, and phosphorylation) play in regulating myocardial stiffness and contractility. We then consider how this regulation becomes unbalanced in heart disease, with an emphasis on changes in titin stiffness and protein quality control. In this context, new insights into the key pathomechanisms of human cardiomyopathy due to a truncation in the titin gene (TTN) are discussed. Along the way, we touch on the potential for titin to be therapeutically targeted to treat acquired or inherited cardiac conditions, such as HFpEF or TTN-truncation cardiomyopathy.
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Affiliation(s)
- Christine M Loescher
- Institute of Physiology II, University Hospital Münster, Robert-Koch-Str. 27B, Münster, 48149 Germany
| | - Anastasia J Hobbach
- Department of Cardiology I, Coronary, Peripheral Vascular Disease and Heart Failure, University Hospital Münster, Münster, Germany
| | - Wolfgang A Linke
- Institute of Physiology II, University Hospital Münster, Robert-Koch-Str. 27B, Münster, 48149 Germany
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11
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RBM20-Related Cardiomyopathy: Current Understanding and Future Options. J Clin Med 2021; 10:jcm10184101. [PMID: 34575212 PMCID: PMC8468976 DOI: 10.3390/jcm10184101] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Revised: 09/07/2021] [Accepted: 09/08/2021] [Indexed: 12/13/2022] Open
Abstract
Splice regulators play an essential role in the transcriptomic diversity of all eukaryotic cell types and organ systems. Recent evidence suggests a contribution of splice-regulatory networks in many diseases, such as cardiomyopathies. Adaptive splice regulators, such as RNA-binding motif protein 20 (RBM20) determine the physiological mRNA landscape formation, and rare variants in the RBM20 gene explain up to 6% of genetic dilated cardiomyopathy (DCM) cases. With ample knowledge from RBM20-deficient mice, rats, swine and induced pluripotent stem cells (iPSCs), the downstream targets and quantitative effects on splicing are now well-defined and the prerequisites for corrective therapeutic approaches are set. This review article highlights some of the recent advances in the field, ranging from aspects of granule formation to 3D genome architectures underlying RBM20-related cardiomyopathy. Promising therapeutic strategies are presented and put into context with the pathophysiological characteristics of RBM20-related diseases.
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12
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The Sarcomeric Spring Protein Titin: Biophysical Properties, Molecular Mechanisms, and Genetic Mutations Associated with Heart Failure and Cardiomyopathy. Curr Cardiol Rep 2021; 23:121. [PMID: 34269900 DOI: 10.1007/s11886-021-01550-y] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 04/07/2021] [Indexed: 01/06/2023]
Abstract
PURPOSE OF REVIEW The giant protein titin forms the "elastic" filament of the sarcomere, essential for the mechanical compliance of the heart muscle. Titin serves a biological spring, and therefore structural modifications of titin affect function of the myocardium and are associated with heart failure and cardiomyopathy. RECENT FINDINGS In this review, we discuss the current understanding of titin's biophysical properties and how modifications contribute to cardiac function and heart failure. In addition, we review the most recent data on the clinical impact and phenotype heterogeneity of TTN truncating variants, including diseases involving striated muscles, and prospects for future therapies. Because of the giant structure of the titin protein and the complexity of its function, titin's role in health and disease is not yet completely understood. Future research efforts need to focus on novel therapeutic approaches able to modulate titin transcriptional and post-translational modification.
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13
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Boeckel JN, Möbius-Winkler M, Müller M, Rebs S, Eger N, Schoppe L, Tappu R, Kokot KE, Kneuer JM, Gaul S, Bordalo DM, Lai A, Haas J, Ghanbari M, Drewe-Boss P, Liss M, Katus HA, Ohler U, Gotthardt M, Laufs U, Streckfuss-Bömeke K, Meder B. SLM2 Is A Novel Cardiac Splicing Factor Involved in Heart Failure due to Dilated Cardiomyopathy. GENOMICS PROTEOMICS & BIOINFORMATICS 2021; 20:129-146. [PMID: 34273561 PMCID: PMC9510876 DOI: 10.1016/j.gpb.2021.01.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Accepted: 02/01/2021] [Indexed: 01/09/2023]
Abstract
Alternative mRNA splicing is a fundamental process to increase the versatility of the genome. In humans, cardiac mRNA splicing is involved in the pathophysiology of heart failure. Mutations in the splicing factor RNA binding motif protein 20 (RBM20) cause severe forms of cardiomyopathy. To identify novel cardiomyopathy-associated splicing factors, RNA-seq and tissue-enrichment analyses were performed, which identified up-regulated expression of Sam68-Like mammalian protein 2 (SLM2) in the left ventricle of dilated cardiomyopathy (DCM) patients. In the human heart, SLM2 binds to important transcripts of sarcomere constituents, such as those encoding myosin light chain 2 (MYL2), troponin I3 (TNNI3), troponin T2 (TNNT2), tropomyosin 1/2 (TPM1/2), and titin (TTN). Mechanistically, SLM2 mediates intron retention, prevents exon exclusion, and thereby mediates alternative splicing of the mRNA regions encoding the variable proline-, glutamate-, valine-, and lysine-rich (PEVK) domain and another part of the I-band region of titin. In summary, SLM2 is a novel cardiac splicing regulator with essential functions for maintaining cardiomyocyte integrity by binding to and processing the mRNAs of essential cardiac constituents such as titin.
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Affiliation(s)
- Jes-Niels Boeckel
- Department of Cardiology, Angiology and Pneumology, University Hospital Heidelberg, Heidelberg 69120, Germany; Klinik und Poliklinik für Kardiologie, Universitätskrankenhaus Leipzig, Leipzig 04103, Germany
| | | | - Marion Müller
- Department of Cardiology, Angiology and Pneumology, University Hospital Heidelberg, Heidelberg 69120, Germany; German Center for Cardiovascular Research (DZHK), Partner site Heidelberg, Heidelberg 69120, Germany; Clinic for General and Interventional Cardiology/ Angiology, Herz- und Diabeteszentrum NRW, Ruhr-Universität Bochum, Bad Oeynhausen 32545, Germany
| | - Sabine Rebs
- Department of Cardiology and Pneumology, University Hospital, Georg-August University Goettingen, Goettingen 37075, Germany; German Center for Cardiovascular Research (DZHK), Partner site Goettingen, Goettingen 37075, Germany
| | - Nicole Eger
- Department of Cardiology, Angiology and Pneumology, University Hospital Heidelberg, Heidelberg 69120, Germany
| | - Laura Schoppe
- Department of Cardiology, Angiology and Pneumology, University Hospital Heidelberg, Heidelberg 69120, Germany
| | - Rewati Tappu
- Department of Cardiology, Angiology and Pneumology, University Hospital Heidelberg, Heidelberg 69120, Germany
| | - Karoline E Kokot
- Klinik und Poliklinik für Kardiologie, Universitätskrankenhaus Leipzig, Leipzig 04103, Germany
| | - Jasmin M Kneuer
- Klinik und Poliklinik für Kardiologie, Universitätskrankenhaus Leipzig, Leipzig 04103, Germany
| | - Susanne Gaul
- Klinik und Poliklinik für Kardiologie, Universitätskrankenhaus Leipzig, Leipzig 04103, Germany
| | - Diana M Bordalo
- Department of Cardiology, Angiology and Pneumology, University Hospital Heidelberg, Heidelberg 69120, Germany; German Center for Cardiovascular Research (DZHK), Partner site Heidelberg, Heidelberg 69120, Germany
| | - Alan Lai
- Department of Cardiology, Angiology and Pneumology, University Hospital Heidelberg, Heidelberg 69120, Germany; German Center for Cardiovascular Research (DZHK), Partner site Heidelberg, Heidelberg 69120, Germany
| | - Jan Haas
- Department of Cardiology, Angiology and Pneumology, University Hospital Heidelberg, Heidelberg 69120, Germany; German Center for Cardiovascular Research (DZHK), Partner site Heidelberg, Heidelberg 69120, Germany
| | - Mahsa Ghanbari
- Berlin Institute for Medical Systems Biology, Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin 10115, Germany; Institute of Biology, Humboldt Universität zu Berlin, Berlin 10099, Germany
| | - Philipp Drewe-Boss
- Berlin Institute for Medical Systems Biology, Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin 10115, Germany; Institute of Biology, Humboldt Universität zu Berlin, Berlin 10099, Germany
| | - Martin Liss
- Neuromuscular and Cardiovascular Cell Biology, Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin 13092, Germany; German Center for Cardiovascular Research (DZHK), Partner site Berlin, Berlin 10117, Germany
| | - Hugo A Katus
- Department of Cardiology, Angiology and Pneumology, University Hospital Heidelberg, Heidelberg 69120, Germany; German Center for Cardiovascular Research (DZHK), Partner site Heidelberg, Heidelberg 69120, Germany
| | - Uwe Ohler
- Berlin Institute for Medical Systems Biology, Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin 10115, Germany; Institute of Biology, Humboldt Universität zu Berlin, Berlin 10099, Germany
| | - Michael Gotthardt
- Neuromuscular and Cardiovascular Cell Biology, Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin 13092, Germany; German Center for Cardiovascular Research (DZHK), Partner site Berlin, Berlin 10117, Germany
| | - Ulrich Laufs
- Klinik und Poliklinik für Kardiologie, Universitätskrankenhaus Leipzig, Leipzig 04103, Germany
| | - Katrin Streckfuss-Bömeke
- Department of Cardiology and Pneumology, University Hospital, Georg-August University Goettingen, Goettingen 37075, Germany; German Center for Cardiovascular Research (DZHK), Partner site Goettingen, Goettingen 37075, Germany
| | - Benjamin Meder
- Department of Cardiology, Angiology and Pneumology, University Hospital Heidelberg, Heidelberg 69120, Germany; German Center for Cardiovascular Research (DZHK), Partner site Heidelberg, Heidelberg 69120, Germany; Stanford Genome Technology Center, Department of Genetics, Stanford Medical School, Palo Alto, CA 94304, USA.
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14
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Briganti F, Sun H, Wei W, Wu J, Zhu C, Liss M, Karakikes I, Rego S, Cipriano A, Snyder M, Meder B, Xu Z, Millat G, Gotthardt M, Mercola M, Steinmetz LM. iPSC Modeling of RBM20-Deficient DCM Identifies Upregulation of RBM20 as a Therapeutic Strategy. Cell Rep 2021; 32:108117. [PMID: 32905764 PMCID: PMC8168789 DOI: 10.1016/j.celrep.2020.108117] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2020] [Revised: 07/11/2020] [Accepted: 08/17/2020] [Indexed: 12/12/2022] Open
Abstract
Recent advances in induced pluripotent stem cell (iPSC) technology and directed differentiation of iPSCs into cardiomyocytes (iPSC-CMs) make it possible to model genetic heart disease in vitro. We apply CRISPR/Cas9 genome editing technology to introduce three RBM20 mutations in iPSCs and differentiate them into iPSC-CMs to establish an in vitro model of RBM20 mutant dilated cardiomyopathy (DCM). In iPSC-CMs harboring a known causal RBM20 variant, the splicing of RBM20 target genes, calcium handling, and contractility are impaired consistent with the disease manifestation in patients. A variant (Pro633Leu) identified by exome sequencing of patient genomes displays the same disease phenotypes, thus establishing this variant as disease causing. We find that all-trans retinoic acid upregulates RBM20 expression and reverts the splicing, calcium handling, and contractility defects in iPSC-CMs with different causal RBM20 mutations. These results suggest that pharmacological upregulation of RBM20 expression is a promising therapeutic strategy for DCM patients with a heterozygous mutation in RBM20. Briganti et al. use iPSC and CRISPR/Cas9 to create a model of RBM20-deficient dilated cardiomyopathy (DCM) that recapitulates mRNA splicing and contractile defects of the disease. They evaluate pharmacological upregulation of RBM20 as a therapeutic strategy. All-trans retinoic acid upregulates RBM20 expression and ameliorates the in vitro hallmarks of disease.
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Affiliation(s)
- Francesca Briganti
- European Molecular Biology Laboratory (EMBL), Genome Biology Unit, Heidelberg, Germany; Collaboration for joint PhD degree between EMBL and Heidelberg University, Faculty of Biosciences, Heidelberg, Germany; Department of Genetics, School of Medicine, Stanford University, Stanford, CA, USA; Cardiovascular Institute and Department of Medicine, Stanford University, Stanford, CA, USA
| | - Han Sun
- Department of Genetics, School of Medicine, Stanford University, Stanford, CA, USA
| | - Wu Wei
- Stanford Genome Technology Center, Stanford University, Palo Alto, CA, USA
| | - Jingyan Wu
- Department of Genetics, School of Medicine, Stanford University, Stanford, CA, USA
| | - Chenchen Zhu
- Department of Genetics, School of Medicine, Stanford University, Stanford, CA, USA
| | - Martin Liss
- Neuromuscular and Cardiovascular Cell Biology, Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Ioannis Karakikes
- Cardiovascular Institute and Department of Cardiothoracic Surgery, Stanford University, Stanford, CA, USA
| | - Shannon Rego
- Department of Genetics, School of Medicine, Stanford University, Stanford, CA, USA
| | - Andrea Cipriano
- Department of Obstetrics and Gynecology, Stanford University, Stanford, CA, USA
| | - Michael Snyder
- Department of Genetics, School of Medicine, Stanford University, Stanford, CA, USA
| | - Benjamin Meder
- Stanford Genome Technology Center, Stanford University, Palo Alto, CA, USA; Institute for Cardiomyopathies Heidelberg and Department of Internal Medicine III, University of Heidelberg, Heidelberg, Germany
| | - Zhenyu Xu
- SOPHiA Genetics, St. Sulpice, Switzerland
| | - Gilles Millat
- Laboratoire de Cardiogénétique Moléculaire, Centre de Biologie et Pathologie Est, Hospices Civils de Lyon, Lyon, France
| | - Michael Gotthardt
- Neuromuscular and Cardiovascular Cell Biology, Max Delbrück Center for Molecular Medicine, Berlin, Germany; Department of Cardiology, Charité-Universitätsmedizin Berlin, Berlin, Germany; DZHK: German Center for Cardiovascular Research, Partner Site Berlin, Berlin, Germany
| | - Mark Mercola
- Cardiovascular Institute and Department of Medicine, Stanford University, Stanford, CA, USA.
| | - Lars M Steinmetz
- European Molecular Biology Laboratory (EMBL), Genome Biology Unit, Heidelberg, Germany; Department of Genetics, School of Medicine, Stanford University, Stanford, CA, USA; Cardiovascular Institute and Department of Medicine, Stanford University, Stanford, CA, USA; Stanford Genome Technology Center, Stanford University, Palo Alto, CA, USA; DZHK: German Center for Cardiovascular Research, Partner Site EMBL Heidelberg, Heidelberg, Germany.
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15
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Abstract
PURPOSE OF REVIEW This review aims to give an update on recent findings related to the cardiac splicing factor RNA-binding motif protein 20 (RBM20) and RBM20 cardiomyopathy, a form of dilated cardiomyopathy caused by mutations in RBM20. RECENT FINDINGS While most research on RBM20 splicing targets has focused on titin (TTN), multiple studies over the last years have shown that other splicing targets of RBM20 including Ca2+/calmodulin-dependent kinase IIδ (CAMK2D) might be critically involved in the development of RBM20 cardiomyopathy. In this regard, loss of RBM20 causes an abnormal intracellular calcium handling, which may relate to the arrhythmogenic presentation of RBM20 cardiomyopathy. In addition, RBM20 presents clinically in a highly gender-specific manner, with male patients suffering from an earlier disease onset and a more severe disease progression. Further research on RBM20, and treatment of RBM20 cardiomyopathy, will need to consider both the multitude and relative contribution of the different splicing targets and related pathways, as well as gender differences.
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16
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Vakhrushev Y, Kozyreva A, Semenov A, Sokolnikova P, Lubimtseva T, Lebedev D, Smolina N, Zhuk S, Mitrofanova L, Vasichkina E, Kostareva A. RBM20-Associated Ventricular Arrhythmias in a Patient with Structurally Normal Heart. Genes (Basel) 2021; 12:genes12010094. [PMID: 33450993 PMCID: PMC7828370 DOI: 10.3390/genes12010094] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Revised: 12/30/2020] [Accepted: 01/08/2021] [Indexed: 12/15/2022] Open
Abstract
RBM20 (RNA-binding motif protein 20) is a splicing factor targeting multiple cardiac genes, and its mutations cause cardiomyopathies. Originally, RBM20 mutations were discovered to cause the development of dilated cardiomyopathy by erroneous splicing of the gene TTN (titin). Titin is a giant protein found in a structure of the sarcomere that functions as a molecular spring and provides a passive stiffness to the cardiomyocyte. Later, RBM20 mutations were also described in association with arrhythmogenic right ventricular cardiomyopathy and left ventricular noncompaction cardiomyopathy. Here, we present a clinical case of a rare arrhythmogenic phenotype and no structural cardiac abnormalities associated with a RBM20 genetic variant of uncertain significance.
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Affiliation(s)
- Yuriy Vakhrushev
- Almazov National Medical Research Centre, Institute of Molecular biology and Genetics, 197341 Saint Petersburg, Russia; (A.K.); (A.S.); (P.S.); (T.L.); (D.L.); (N.S.); (S.Z.); (L.M.); (E.V.); (A.K.)
- Correspondence: ; Tel.: +7-9819513039
| | - Alexandra Kozyreva
- Almazov National Medical Research Centre, Institute of Molecular biology and Genetics, 197341 Saint Petersburg, Russia; (A.K.); (A.S.); (P.S.); (T.L.); (D.L.); (N.S.); (S.Z.); (L.M.); (E.V.); (A.K.)
| | - Andrey Semenov
- Almazov National Medical Research Centre, Institute of Molecular biology and Genetics, 197341 Saint Petersburg, Russia; (A.K.); (A.S.); (P.S.); (T.L.); (D.L.); (N.S.); (S.Z.); (L.M.); (E.V.); (A.K.)
| | - Polina Sokolnikova
- Almazov National Medical Research Centre, Institute of Molecular biology and Genetics, 197341 Saint Petersburg, Russia; (A.K.); (A.S.); (P.S.); (T.L.); (D.L.); (N.S.); (S.Z.); (L.M.); (E.V.); (A.K.)
| | - Tamara Lubimtseva
- Almazov National Medical Research Centre, Institute of Molecular biology and Genetics, 197341 Saint Petersburg, Russia; (A.K.); (A.S.); (P.S.); (T.L.); (D.L.); (N.S.); (S.Z.); (L.M.); (E.V.); (A.K.)
| | - Dmitry Lebedev
- Almazov National Medical Research Centre, Institute of Molecular biology and Genetics, 197341 Saint Petersburg, Russia; (A.K.); (A.S.); (P.S.); (T.L.); (D.L.); (N.S.); (S.Z.); (L.M.); (E.V.); (A.K.)
| | - Natalia Smolina
- Almazov National Medical Research Centre, Institute of Molecular biology and Genetics, 197341 Saint Petersburg, Russia; (A.K.); (A.S.); (P.S.); (T.L.); (D.L.); (N.S.); (S.Z.); (L.M.); (E.V.); (A.K.)
| | - Sergey Zhuk
- Almazov National Medical Research Centre, Institute of Molecular biology and Genetics, 197341 Saint Petersburg, Russia; (A.K.); (A.S.); (P.S.); (T.L.); (D.L.); (N.S.); (S.Z.); (L.M.); (E.V.); (A.K.)
| | - Lubov Mitrofanova
- Almazov National Medical Research Centre, Institute of Molecular biology and Genetics, 197341 Saint Petersburg, Russia; (A.K.); (A.S.); (P.S.); (T.L.); (D.L.); (N.S.); (S.Z.); (L.M.); (E.V.); (A.K.)
| | - Elena Vasichkina
- Almazov National Medical Research Centre, Institute of Molecular biology and Genetics, 197341 Saint Petersburg, Russia; (A.K.); (A.S.); (P.S.); (T.L.); (D.L.); (N.S.); (S.Z.); (L.M.); (E.V.); (A.K.)
| | - Anna Kostareva
- Almazov National Medical Research Centre, Institute of Molecular biology and Genetics, 197341 Saint Petersburg, Russia; (A.K.); (A.S.); (P.S.); (T.L.); (D.L.); (N.S.); (S.Z.); (L.M.); (E.V.); (A.K.)
- Department of Women’s and Children’s Health and Center for Molecular Medicine, Karolinska Institute, 17177 Stockholm, Sweden
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17
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Modifications of Titin Contribute to the Progression of Cardiomyopathy and Represent a Therapeutic Target for Treatment of Heart Failure. J Clin Med 2020; 9:jcm9092770. [PMID: 32859027 PMCID: PMC7564493 DOI: 10.3390/jcm9092770] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 08/22/2020] [Accepted: 08/24/2020] [Indexed: 12/20/2022] Open
Abstract
Titin is the largest human protein and an essential component of the cardiac sarcomere. With multiple immunoglobulin(Ig)-like domains that serve as molecular springs, titin contributes significantly to the passive tension, systolic function, and diastolic function of the heart. Mutations leading to early termination of titin are the most common genetic cause of dilated cardiomyopathy. Modifications of titin, which change protein length, and relative stiffness affect resting tension of the ventricle and are associated with acquired forms of heart failure. Transcriptional and post-translational changes that increase titin’s length and extensibility, making the sarcomere longer and softer, are associated with systolic dysfunction and left ventricular dilation. Modifications of titin that decrease its length and extensibility, making the sarcomere shorter and stiffer, are associated with diastolic dysfunction in animal models. There has been significant progress in understanding the mechanisms by which titin is modified. As molecular pathways that modify titin’s mechanical properties are elucidated, they represent therapeutic targets for treatment of both systolic and diastolic dysfunction. In this article, we review titin’s contribution to normal cardiac physiology, the pathophysiology of titin truncation variations leading to dilated cardiomyopathy, and transcriptional and post-translational modifications of titin. Emphasis is on how modification of titin can be utilized as a therapeutic target for treatment of heart failure.
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18
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Fochi S, Lorenzi P, Galasso M, Stefani C, Trabetti E, Zipeto D, Romanelli MG. The Emerging Role of the RBM20 and PTBP1 Ribonucleoproteins in Heart Development and Cardiovascular Diseases. Genes (Basel) 2020; 11:genes11040402. [PMID: 32276354 PMCID: PMC7230170 DOI: 10.3390/genes11040402] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Revised: 04/04/2020] [Accepted: 04/06/2020] [Indexed: 12/17/2022] Open
Abstract
Alternative splicing is a regulatory mechanism essential for cell differentiation and tissue organization. More than 90% of human genes are regulated by alternative splicing events, which participate in cell fate determination. The general mechanisms of splicing events are well known, whereas only recently have deep-sequencing, high throughput analyses and animal models provided novel information on the network of functionally coordinated, tissue-specific, alternatively spliced exons. Heart development and cardiac tissue differentiation require thoroughly regulated splicing events. The ribonucleoprotein RBM20 is a key regulator of the alternative splicing events required for functional and structural heart properties, such as the expression of TTN isoforms. Recently, the polypyrimidine tract-binding protein PTBP1 has been demonstrated to participate with RBM20 in regulating splicing events. In this review, we summarize the updated knowledge relative to RBM20 and PTBP1 structure and molecular function; their role in alternative splicing mechanisms involved in the heart development and function; RBM20 mutations associated with idiopathic dilated cardiovascular disease (DCM); and the consequences of RBM20-altered expression or dysfunction. Furthermore, we discuss the possible application of targeting RBM20 in new approaches in heart therapies.
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19
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Slater RE, Strom JG, Methawasin M, Liss M, Gotthardt M, Sweitzer N, Granzier HL. Metformin improves diastolic function in an HFpEF-like mouse model by increasing titin compliance. J Gen Physiol 2018; 151:42-52. [PMID: 30567709 PMCID: PMC6314384 DOI: 10.1085/jgp.201812259] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Accepted: 11/14/2018] [Indexed: 12/20/2022] Open
Abstract
Heart failure with preserved ejection fraction (HFpEF) is a syndrome characterized by increased diastolic stiffness, for which effective therapies are lacking. Slater et al. show that metformin lowers titin-based passive stiffness in an HFpEF mouse model and may therefore be of therapeutic benefit. Heart failure with preserved ejection fraction (HFpEF) is a complex syndrome characterized by a preserved ejection fraction but increased diastolic stiffness and abnormalities of filling. Although the prevalence of HFpEF is high and continues to rise, no effective therapies exist; however, the diabetic drug metformin has been associated with improved diastolic function in diabetic patients. Here we determine the therapeutic potential of metformin for improving diastolic function in a mouse model with HFpEF-like symptoms. We combine transverse aortic constriction (TAC) surgery with deoxycorticosterone acetate (DOCA) supplementation to obtain a mouse model with increased diastolic stiffness and exercise intolerance. Echocardiography and pressure–volume analysis reveal that providing metformin to TAC/DOCA mice improves diastolic function in the left ventricular (LV) chamber. Muscle mechanics show that metformin lowers passive stiffness of the LV wall muscle. Concomitant with this improvement in diastolic function, metformin-treated TAC/DOCA mice also demonstrate preserved exercise capacity. No metformin effects are seen in sham operated mice. Extraction experiments on skinned ventricular muscle strips show that the metformin-induced reduction of passive stiffness in TAC/DOCA mice is due to an increase in titin compliance. Using phospho-site-specific antibodies, we assay the phosphorylation of titin’s PEVK and N2B spring elements. Metformin-treated mice have unaltered PEVK phosphorylation but increased phosphorylation of PKA sites in the N2B element, a change which has previously been shown to lower titin’s stiffness. Consistent with this result, experiments with a mouse model deficient in the N2B element reveal that the beneficial effect of metformin on LV chamber and muscle stiffness requires the presence of the N2B element. We conclude that metformin offers therapeutic benefit during HFpEF by lowering titin-based passive stiffness.
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Affiliation(s)
- Rebecca E Slater
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ
| | - Joshua G Strom
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ
| | - Mei Methawasin
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ
| | - Martin Liss
- Neuromuscular and Cardiovascular Cell Biology, Max Delbrück Center for Molecular Medicine, Berlin, Germany.,German Center for Cardiovascular Research, Partner Site Berlin, Berlin, Germany
| | - Michael Gotthardt
- Neuromuscular and Cardiovascular Cell Biology, Max Delbrück Center for Molecular Medicine, Berlin, Germany.,German Center for Cardiovascular Research, Partner Site Berlin, Berlin, Germany
| | - Nancy Sweitzer
- Sarver Heart Center, College of Medicine, University of Arizona, Tucson, AZ
| | - Henk L Granzier
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ .,Sarver Heart Center, College of Medicine, University of Arizona, Tucson, AZ
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20
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Watanabe T, Kimura A, Kuroyanagi H. Alternative Splicing Regulator RBM20 and Cardiomyopathy. Front Mol Biosci 2018; 5:105. [PMID: 30547036 PMCID: PMC6279932 DOI: 10.3389/fmolb.2018.00105] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Accepted: 11/09/2018] [Indexed: 12/17/2022] Open
Abstract
RBM20 is a vertebrate-specific RNA-binding protein with two zinc finger (ZnF) domains, one RNA-recognition motif (RRM)-type RNA-binding domain and an arginine/serine (RS)-rich region. RBM20 has initially been identified as one of dilated cardiomyopathy (DCM)-linked genes. RBM20 is a regulator of heart-specific alternative splicing and Rbm20ΔRRM mice lacking the RRM domain are defective in the splicing regulation. The Rbm20ΔRRM mice, however, do not exhibit a characteristic DCM-like phenotype such as dilatation of left ventricles or systolic dysfunction. Considering that most of the RBM20 mutations identified in familial DCM cases were heterozygous missense mutations in an arginine-serine-arginine-serine-proline (RSRSP) stretch whose phosphorylation is crucial for nuclear localization of RBM20, characterization of a knock-in animal model is awaited. One of the major targets for RBM20 is the TTN gene, which is comprised of the largest number of exons in mammals. Alternative splicing of the TTN gene is exceptionally complicated and RBM20 represses >160 of its consecutive exons, yet detailed mechanisms for such extraordinary regulation are to be elucidated. The TTN gene encodes the largest known protein titin, a multi-functional sarcomeric structural protein specific to striated muscles. As titin is the most important factor for passive tension of cardiomyocytes, extensive heart-specific and developmentally regulated alternative splicing of the TTN pre-mRNA by RBM20 plays a critical role in passive stiffness and diastolic function of the heart. In disease models with diastolic dysfunctions, the phenotypes were rescued by increasing titin compliance through manipulation of the Ttn pre-mRNA splicing, raising RBM20 as a potential therapeutic target.
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Affiliation(s)
- Takeshi Watanabe
- Laboratory of Gene Expression, Medical Research Institute, Tokyo Medical and Dental University (TMDU), Tokyo, Japan.,Department of Psychosomatic Dentistry, Graduate School of Medical and Dental Science, Tokyo Medical and Dental University (TMDU), Tokyo, Japan
| | - Akinori Kimura
- Division of Pathology, Department of Molecular Pathogenesis, Medical Research Institute, Tokyo Medical and Dental University (TMDU), Tokyo, Japan.,Laboratory for Integrated Research Projects on Intractable Diseases Advanced Technology Laboratories, Medical Research Institute, Tokyo Medical and Dental University (TMDU), Tokyo, Japan
| | - Hidehito Kuroyanagi
- Laboratory of Gene Expression, Medical Research Institute, Tokyo Medical and Dental University (TMDU), Tokyo, Japan.,Laboratory for Integrated Research Projects on Intractable Diseases Advanced Technology Laboratories, Medical Research Institute, Tokyo Medical and Dental University (TMDU), Tokyo, Japan.,Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles, Los Angeles, CA, United States
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