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André LM, Ausems CRM, Wansink DG, Wieringa B. Abnormalities in Skeletal Muscle Myogenesis, Growth, and Regeneration in Myotonic Dystrophy. Front Neurol 2018; 9:368. [PMID: 29892259 PMCID: PMC5985300 DOI: 10.3389/fneur.2018.00368] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Accepted: 05/07/2018] [Indexed: 12/16/2022] Open
Abstract
Myotonic dystrophy type 1 (DM1) and 2 (DM2) are autosomal dominant degenerative neuromuscular disorders characterized by progressive skeletal muscle weakness, atrophy, and myotonia with progeroid features. Although both DM1 and DM2 are characterized by skeletal muscle dysfunction and also share other clinical features, the diseases differ in the muscle groups that are affected. In DM1, distal muscles are mainly affected, whereas in DM2 problems are mostly found in proximal muscles. In addition, manifestation in DM1 is generally more severe, with possible congenital or childhood-onset of disease and prominent CNS involvement. DM1 and DM2 are caused by expansion of (CTG•CAG)n and (CCTG•CAGG)n repeats in the 3' non-coding region of DMPK and in intron 1 of CNBP, respectively, and in overlapping antisense genes. This critical review will focus on the pleiotropic problems that occur during development, growth, regeneration, and aging of skeletal muscle in patients who inherited these expansions. The current best-accepted idea is that most muscle symptoms can be explained by pathomechanistic effects of repeat expansion on RNA-mediated pathways. However, aberrations in DNA replication and transcription of the DM loci or in protein translation and proteome homeostasis could also affect the control of proliferation and differentiation of muscle progenitor cells or the maintenance and physiological integrity of muscle fibers during a patient's lifetime. Here, we will discuss these molecular and cellular processes and summarize current knowledge about the role of embryonic and adult muscle-resident stem cells in growth, homeostasis, regeneration, and premature aging of healthy and diseased muscle tissue. Of particular interest is that also progenitor cells from extramuscular sources, such as pericytes and mesoangioblasts, can participate in myogenic differentiation. We will examine the potential of all these types of cells in the application of regenerative medicine for muscular dystrophies and evaluate new possibilities for their use in future therapy of DM.
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Affiliation(s)
- Laurène M André
- Department of Cell Biology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, Netherlands
| | - C Rosanne M Ausems
- Department of Genetics, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, Nijmegen, Netherlands
| | - Derick G Wansink
- Department of Cell Biology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, Netherlands
| | - Bé Wieringa
- Department of Cell Biology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, Netherlands
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52
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Matloka M, Klein AF, Rau F, Furling D. Cells of Matter- In Vitro Models for Myotonic Dystrophy. Front Neurol 2018; 9:361. [PMID: 29875732 PMCID: PMC5974047 DOI: 10.3389/fneur.2018.00361] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Accepted: 05/03/2018] [Indexed: 12/17/2022] Open
Abstract
Myotonic dystrophy type 1 (DM1 also known as Steinert disease) is a multisystemic disorder mainly characterized by myotonia, progressive muscle weakness and wasting, cognitive impairments, and cardiac defects. This autosomal dominant disease is caused by the expression of nuclear retained RNAs containing pathologic expanded CUG repeats that alter the function of RNA-binding proteins in a tissue-specific manner, leading ultimately to neuromuscular dysfunction and clinical symptoms. Although considerable knowledge has been gathered on myotonic dystrophy since its first description, the development of novel relevant disease models remains of high importance to investigate pathophysiologic mechanisms and to assess new therapeutic approaches. In addition to animal models, in vitro cell cultures provide a unique resource for both fundamental and translational research. This review discusses how cellular models broke ground to decipher molecular basis of DM1 and describes currently available cell models, ranging from exogenous expression of the CTG tracts to variable patients' derived cells.
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Affiliation(s)
| | | | | | - Denis Furling
- Sorbonne Université, INSERM, Association Institut de Myologie, Centre de Recherche en Myologie, Paris, France
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53
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Sellier C, Cerro-Herreros E, Blatter M, Freyermuth F, Gaucherot A, Ruffenach F, Sarkar P, Puymirat J, Udd B, Day JW, Meola G, Bassez G, Fujimura H, Takahashi MP, Schoser B, Furling D, Artero R, Allain FHT, Llamusi B, Charlet-Berguerand N. rbFOX1/MBNL1 competition for CCUG RNA repeats binding contributes to myotonic dystrophy type 1/type 2 differences. Nat Commun 2018; 9:2009. [PMID: 29789616 PMCID: PMC5964235 DOI: 10.1038/s41467-018-04370-x] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Accepted: 04/26/2018] [Indexed: 12/30/2022] Open
Abstract
Myotonic dystrophy type 1 and type 2 (DM1, DM2) are caused by expansions of CTG and CCTG repeats, respectively. RNAs containing expanded CUG or CCUG repeats interfere with the metabolism of other RNAs through titration of the Muscleblind-like (MBNL) RNA binding proteins. DM2 follows a more favorable clinical course than DM1, suggesting that specific modifiers may modulate DM severity. Here, we report that the rbFOX1 RNA binding protein binds to expanded CCUG RNA repeats, but not to expanded CUG RNA repeats. Interestingly, rbFOX1 competes with MBNL1 for binding to CCUG expanded repeats and overexpression of rbFOX1 partly releases MBNL1 from sequestration within CCUG RNA foci in DM2 muscle cells. Furthermore, expression of rbFOX1 corrects alternative splicing alterations and rescues muscle atrophy, climbing and flying defects caused by expression of expanded CCUG repeats in a Drosophila model of DM2.
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Affiliation(s)
- Chantal Sellier
- IGBMC, INSERM U964, CNRS UMR7104, University of Strasbourg, 67404, Illkirch, France
| | - Estefanía Cerro-Herreros
- Translational Genomics Group, Interdisciplinary Research Structure for Biotechnology and Biomedicine BIOTECMED, University of Valencia, 46010, Valencia, Spain
- INCLIVA Health Research Institute, 46010, Valencia, Spain
| | - Markus Blatter
- Institute for Molecular Biology and Biophysics, Swiss Federal Institute of Technology (ETH) Zurich, 8092, Zurich, Switzerland
| | - Fernande Freyermuth
- IGBMC, INSERM U964, CNRS UMR7104, University of Strasbourg, 67404, Illkirch, France
| | - Angeline Gaucherot
- IGBMC, INSERM U964, CNRS UMR7104, University of Strasbourg, 67404, Illkirch, France
| | - Frank Ruffenach
- IGBMC, INSERM U964, CNRS UMR7104, University of Strasbourg, 67404, Illkirch, France
| | - Partha Sarkar
- Department of Neurology, University of Texas Medical Branch, Galveston, TX, 77555, USA
| | - Jack Puymirat
- Human Genetics Research Unit, Laval University, CHUQ, Ste-Foy, Quebec, QC G1V 4G2, Canada
| | - Bjarne Udd
- Neuromuscular Research Center, Tampere University Hospital, 33521, Tampere, Finland
- Department of Medical Genetics, Folkhälsan Institute of Genetics, Helsinki University, 00290, Helsinki, Finland
- Department of Neurology, Vasa Central Hospital, 65130, Vaasa, Finland
| | - John W Day
- Department of Neurology, Stanford University, San Francisco, CA, 94305, USA
| | - Giovanni Meola
- Department of Biomedical Sciences for Health, University of Milan, 20097, Milan, Italy
- Neurology Unit, IRCCS Policlinico San Donato, San Donato Milanese, 20097, Milan, Italy
| | - Guillaume Bassez
- Sorbonne Université, Inserm, Association Institut de Myologie, Center of Research in Myology, 75013, Paris, France
| | - Harutoshi Fujimura
- Department of Neurology, Toneyama National Hospital, Toyonaka, 560-0045, Japan
| | - Masanori P Takahashi
- Department of Neurology, Osaka University Graduate School of Medicine, Suita, 565-0871, Japan
| | - Benedikt Schoser
- Friedrich-Baur-Institute, Department of Neurology, Ludwig Maximilian University, 80539, Munich, Germany
| | - Denis Furling
- Sorbonne Université, Inserm, Association Institut de Myologie, Center of Research in Myology, 75013, Paris, France
| | - Ruben Artero
- Translational Genomics Group, Interdisciplinary Research Structure for Biotechnology and Biomedicine BIOTECMED, University of Valencia, 46010, Valencia, Spain
- INCLIVA Health Research Institute, 46010, Valencia, Spain
| | - Frédéric H T Allain
- Institute for Molecular Biology and Biophysics, Swiss Federal Institute of Technology (ETH) Zurich, 8092, Zurich, Switzerland
| | - Beatriz Llamusi
- Translational Genomics Group, Interdisciplinary Research Structure for Biotechnology and Biomedicine BIOTECMED, University of Valencia, 46010, Valencia, Spain.
- INCLIVA Health Research Institute, 46010, Valencia, Spain.
| | - Nicolas Charlet-Berguerand
- IGBMC, INSERM U964, CNRS UMR7104, University of Strasbourg, 67404, Illkirch, France.
- UMR7104, Centre National de la Recherche Scientifique, 67404, Illkirch, France.
- Institut National de la Santé et de la Recherche Médicale, U964, 67404, Illkirch, France.
- Université de Strasbourg, 67404, Illkirch, France.
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54
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Blue RE, Curry EG, Engels NM, Lee EY, Giudice J. How alternative splicing affects membrane-trafficking dynamics. J Cell Sci 2018; 131:jcs216465. [PMID: 29769303 PMCID: PMC6031328 DOI: 10.1242/jcs.216465] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The cell biology field has outstanding working knowledge of the fundamentals of membrane-trafficking pathways, which are of critical importance in health and disease. Current challenges include understanding how trafficking pathways are fine-tuned for specialized tissue functions in vivo and during development. In parallel, the ENCODE project and numerous genetic studies have revealed that alternative splicing regulates gene expression in tissues and throughout development at a post-transcriptional level. This Review summarizes recent discoveries demonstrating that alternative splicing affects tissue specialization and membrane-trafficking proteins during development, and examines how this regulation is altered in human disease. We first discuss how alternative splicing of clathrin, SNAREs and BAR-domain proteins influences endocytosis, secretion and membrane dynamics, respectively. We then focus on the role of RNA-binding proteins in the regulation of splicing of membrane-trafficking proteins in health and disease. Overall, our aim is to comprehensively summarize how trafficking is molecularly influenced by alternative splicing and identify future directions centered on its physiological relevance.
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Affiliation(s)
- R Eric Blue
- Department of Cell Biology & Physiology, School of Medicine, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Ennessa G Curry
- Department of Cell Biology & Physiology, School of Medicine, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Nichlas M Engels
- Department of Cell Biology & Physiology, School of Medicine, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Eunice Y Lee
- Department of Cell Biology & Physiology, School of Medicine, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Jimena Giudice
- Department of Cell Biology & Physiology, School of Medicine, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
- McAllister Heart Institute, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
- Curriculum in Genetics and Molecular Biology (GMB), The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
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55
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Chakraborty M, Sellier C, Ney M, Pascal V, Charlet-Berguerand N, Artero R, Llamusi B. Daunorubicin reduces MBNL1 sequestration caused by CUG-repeat expansion and rescues cardiac dysfunctions in a Drosophila model of myotonic dystrophy. Dis Model Mech 2018; 11:dmm.032557. [PMID: 29592894 PMCID: PMC5963859 DOI: 10.1242/dmm.032557] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Accepted: 03/14/2018] [Indexed: 01/09/2023] Open
Abstract
Myotonic dystrophy (DM) is a dominantly inherited neuromuscular disorder caused by expression of mutant myotonin-protein kinase (DMPK) transcripts containing expanded CUG repeats. Pathogenic DMPK RNA sequesters the muscleblind-like (MBNL) proteins, causing alterations in metabolism of various RNAs. Cardiac dysfunction represents the second most common cause of death in DM type 1 (DM1) patients. However, the contribution of MBNL sequestration in DM1 cardiac dysfunction is unclear. We overexpressed Muscleblind (Mbl), the DrosophilaMBNL orthologue, in cardiomyocytes of DM1 model flies and observed a rescue of heart dysfunctions, which are characteristic of these model flies and resemble cardiac defects observed in patients. We also identified a drug – daunorubicin hydrochloride – that directly binds to CUG repeats and alleviates Mbl sequestration in Drosophila DM1 cardiomyocytes, resulting in mis-splicing rescue and cardiac function recovery. These results demonstrate the relevance of Mbl sequestration caused by expanded-CUG-repeat RNA in cardiac dysfunctions in DM1, and highlight the potential of strategies aimed at inhibiting this protein-RNA interaction to recover normal cardiac function. Summary: MBNL protein sequestration by expanded CUG RNA contributes towards cardiac dysfunction in a myotonic dystrophy Drosophila model. Here, the authors identify the anticancer drug daunorubicin as a candidate therapeutic for the disease.
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Affiliation(s)
- Mouli Chakraborty
- Translational Genomics Group, Incliva Health Research Institute, Valencia, Spain.,Department of Genetics and Interdisciplinary Research Structure for Biotechnology and Biomedicine (ERI BIOTECMED), University of Valencia, Valencia 46100, Spain.,CIPF-INCLIVA Joint Unit, Valencia 46100, Spain
| | - Chantal Sellier
- Translational Medicine and Neurogenetics, Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U964, CNRS UMR7104, University of Strasbourg, 1 Rue Laurent Fries, 67400 Illkirch-Graffenstaden, France
| | - Michel Ney
- Translational Medicine and Neurogenetics, Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U964, CNRS UMR7104, University of Strasbourg, 1 Rue Laurent Fries, 67400 Illkirch-Graffenstaden, France
| | - Villa Pascal
- PCBIS Plate-forme de Chimie Biologique Intégrative de Strasbourg CNRS UMS 3286, Labex Medalis, ESBS, Université de Strasbourg, 300 Boulevard Sébastien Brant, 67412 Illkirch, France
| | - Nicolas Charlet-Berguerand
- Translational Medicine and Neurogenetics, Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U964, CNRS UMR7104, University of Strasbourg, 1 Rue Laurent Fries, 67400 Illkirch-Graffenstaden, France
| | - Ruben Artero
- Translational Genomics Group, Incliva Health Research Institute, Valencia, Spain .,Department of Genetics and Interdisciplinary Research Structure for Biotechnology and Biomedicine (ERI BIOTECMED), University of Valencia, Valencia 46100, Spain.,CIPF-INCLIVA Joint Unit, Valencia 46100, Spain
| | - Beatriz Llamusi
- Translational Genomics Group, Incliva Health Research Institute, Valencia, Spain.,Department of Genetics and Interdisciplinary Research Structure for Biotechnology and Biomedicine (ERI BIOTECMED), University of Valencia, Valencia 46100, Spain.,CIPF-INCLIVA Joint Unit, Valencia 46100, Spain
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56
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Thomas JD, Oliveira R, Sznajder ŁJ, Swanson MS. Myotonic Dystrophy and Developmental Regulation of RNA Processing. Compr Physiol 2018; 8:509-553. [PMID: 29687899 PMCID: PMC11323716 DOI: 10.1002/cphy.c170002] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Myotonic dystrophy (DM) is a multisystemic disorder caused by microsatellite expansion mutations in two unrelated genes leading to similar, yet distinct, diseases. DM disease presentation is highly variable and distinguished by differences in age-of-onset and symptom severity. In the most severe form, DM presents with congenital onset and profound developmental defects. At the molecular level, DM pathogenesis is characterized by a toxic RNA gain-of-function mechanism that involves the transcription of noncoding microsatellite expansions. These mutant RNAs disrupt key cellular pathways, including RNA processing, localization, and translation. In DM, these toxic RNA effects are predominantly mediated through the modulation of the muscleblind-like and CUGBP and ETR-3-like factor families of RNA binding proteins (RBPs). Dysfunction of these RBPs results in widespread RNA processing defects culminating in the expression of developmentally inappropriate protein isoforms in adult tissues. The tissue that is the focus of this review, skeletal muscle, is particularly sensitive to mutant RNA-responsive perturbations, as patients display a variety of developmental, structural, and functional defects in muscle. Here, we provide a comprehensive overview of DM1 and DM2 clinical presentation and pathology as well as the underlying cellular and molecular defects associated with DM disease onset and progression. Additionally, fundamental aspects of skeletal muscle development altered in DM are highlighted together with ongoing and potential therapeutic avenues to treat this muscular dystrophy. © 2018 American Physiological Society. Compr Physiol 8:509-553, 2018.
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Affiliation(s)
- James D. Thomas
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics and the Genetics Institute, University of Florida, College of Medicine, Gainesville, Florida, USA
| | - Ruan Oliveira
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics and the Genetics Institute, University of Florida, College of Medicine, Gainesville, Florida, USA
| | - Łukasz J. Sznajder
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics and the Genetics Institute, University of Florida, College of Medicine, Gainesville, Florida, USA
| | - Maurice S. Swanson
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics and the Genetics Institute, University of Florida, College of Medicine, Gainesville, Florida, USA
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57
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Kalra S, Montanaro F, Denning C. Can Human Pluripotent Stem Cell-Derived Cardiomyocytes Advance Understanding of Muscular Dystrophies? J Neuromuscul Dis 2018; 3:309-332. [PMID: 27854224 PMCID: PMC5123622 DOI: 10.3233/jnd-150133] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Muscular dystrophies (MDs) are clinically and molecularly a highly heterogeneous group of single-gene disorders that primarily affect striated muscles. Cardiac disease is present in several MDs where it is an important contributor to morbidity and mortality. Careful monitoring of cardiac issues is necessary but current management of cardiac involvement does not effectively protect from disease progression and cardiac failure. There is a critical need to gain new knowledge on the diverse molecular underpinnings of cardiac disease in MDs in order to guide cardiac treatment development and assist in reaching a clearer consensus on cardiac disease management in the clinic. Animal models are available for the majority of MDs and have been invaluable tools in probing disease mechanisms and in pre-clinical screens. However, there are recognized genetic, physiological, and structural differences between human and animal hearts that impact disease progression, manifestation, and response to pharmacological interventions. Therefore, there is a need to develop parallel human systems to model cardiac disease in MDs. This review discusses the current status of cardiomyocytes (CMs) derived from human induced pluripotent stem cells (hiPSC) to model cardiac disease, with a focus on Duchenne muscular dystrophy (DMD) and myotonic dystrophy (DM1). We seek to provide a balanced view of opportunities and limitations offered by this system in elucidating disease mechanisms pertinent to human cardiac physiology and as a platform for treatment development or refinement.
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Affiliation(s)
- Spandan Kalra
- Department of Stem Cell Biology, Centre for Biomolecular Sciences, University of Nottingham, UK
| | - Federica Montanaro
- Dubowitz Neuromuscular Centre, Department of Molecular Neurosciences, University College London - Institute of Child Health, London, UK
| | - Chris Denning
- Department of Stem Cell Biology, Centre for Biomolecular Sciences, University of Nottingham, UK
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58
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Nakka K, Ghigna C, Gabellini D, Dilworth FJ. Diversification of the muscle proteome through alternative splicing. Skelet Muscle 2018; 8:8. [PMID: 29510724 PMCID: PMC5840707 DOI: 10.1186/s13395-018-0152-3] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Accepted: 02/15/2018] [Indexed: 12/16/2022] Open
Abstract
Background Skeletal muscles express a highly specialized proteome that allows the metabolism of energy sources to mediate myofiber contraction. This muscle-specific proteome is partially derived through the muscle-specific transcription of a subset of genes. Surprisingly, RNA sequencing technologies have also revealed a significant role for muscle-specific alternative splicing in generating protein isoforms that give specialized function to the muscle proteome. Main body In this review, we discuss the current knowledge with respect to the mechanisms that allow pre-mRNA transcripts to undergo muscle-specific alternative splicing while identifying some of the key trans-acting splicing factors essential to the process. The importance of specific splicing events to specialized muscle function is presented along with examples in which dysregulated splicing contributes to myopathies. Though there is now an appreciation that alternative splicing is a major contributor to proteome diversification, the emergence of improved “targeted” proteomic methodologies for detection of specific protein isoforms will soon allow us to better appreciate the extent to which alternative splicing modifies the activity of proteins (and their ability to interact with other proteins) in the skeletal muscle. In addition, we highlight a continued need to better explore the signaling pathways that contribute to the temporal control of trans-acting splicing factor activity to ensure specific protein isoforms are expressed in the proper cellular context. Conclusions An understanding of the signal-dependent and signal-independent events driving muscle-specific alternative splicing has the potential to provide us with novel therapeutic strategies to treat different myopathies. Electronic supplementary material The online version of this article (10.1186/s13395-018-0152-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Kiran Nakka
- Sprott Centre for Stem Cell Research, Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, ON, K1H 8L6, Canada
| | - Claudia Ghigna
- Istituto di Genetica Molecolare-Consiglio Nazionale delle Ricerche (IGM-CNR), Pavia, Italy
| | - Davide Gabellini
- Unit of Gene Expression and Muscular Dystrophy, Division of Genetics and Cell Biology, IRCCS San Raffaele Scientific Institute, DIBIT2, 5A3-44, via Olgettina 58, 20132, Milan, Italy.
| | - F Jeffrey Dilworth
- Sprott Centre for Stem Cell Research, Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, ON, K1H 8L6, Canada. .,Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON, K1H 8M5, Canada. .,Sprott Centre for Stem Cell Research, Ottawa Hospital Research Institute, 501 Smyth Rd, Mailbox 511, Ottawa, ON, K1H 8L6, Canada.
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59
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Zhang F, Bodycombe NE, Haskell KM, Sun YL, Wang ET, Morris CA, Jones LH, Wood LD, Pletcher MT. A flow cytometry-based screen identifies MBNL1 modulators that rescue splicing defects in myotonic dystrophy type I. Hum Mol Genet 2018; 26:3056-3068. [PMID: 28535287 PMCID: PMC5886090 DOI: 10.1093/hmg/ddx190] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2016] [Accepted: 05/08/2017] [Indexed: 11/17/2022] Open
Abstract
Myotonic dystrophy Type 1 (DM1) is a rare genetic disease caused by the expansion of CTG trinucleotide repeats ((CTG)exp) in the 3' untranslated region of the DMPK gene. The repeat transcripts sequester the RNA binding protein Muscleblind-like protein 1 (MBNL1) and hamper its normal function in pre-mRNA splicing. Overexpressing exogenous MBNL1 in the DM1 mouse model has been shown to rescue the splicing defects and reverse myotonia. Although a viable therapeutic strategy, pharmacological modulators of MBNL1 expression have not been identified. Here, we engineered a ZsGreen tag into the endogenous MBNL1 locus in HeLa cells and established a flow cytometry-based screening system to identify compounds that increase MBNL1 level. The initial screen of small molecule compound libraries identified more than thirty hits that increased MBNL1 expression greater than double the baseline levels. Further characterization of two hits revealed that the small molecule HDAC inhibitors, ISOX and vorinostat, increased MBNL1 expression in DM1 patient-derived fibroblasts and partially rescued the splicing defect caused by (CUG)exp repeats in these cells. These findings demonstrate the feasibility of this flow-based cytometry screen to identify both small molecule compounds and druggable targets for MBNL1 upregulation.
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Affiliation(s)
| | - Nicole E Bodycombe
- Medicine Design, Worldwide Research and Development, Pfizer, Cambridge, MA 02139, USA
| | - Keith M Haskell
- Pharmacokinetics, Dynamics and Metabolism - New Chemical Entities, Worldwide Research and Development, Pfizer, CT 06340, USA
| | | | - Eric T Wang
- Center for Neurogenetics, University of Florida, Gainesville, FL 32610, USA
| | | | - Lyn H Jones
- Medicine Design, Worldwide Research and Development, Pfizer, Cambridge, MA 02139, USA
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60
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Disturbed Ca 2+ Homeostasis in Muscle-Wasting Disorders. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 1088:307-326. [PMID: 30390258 DOI: 10.1007/978-981-13-1435-3_14] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Ca2+ is essential for proper structure and function of skeletal muscle. It not only activates contraction and force development but also participates in multiple signaling pathways. Low levels of Ca2+ restrain muscle regeneration by limiting the fusion of satellite cells. Ironically, sustained elevations of Ca2+ also result in muscle degeneration as this ion promotes high rates of protein breakdown. Moreover, transforming growth factors (TGFs) which are well known for controlling muscle growth also regulate Ca2+ channels. Thus, therapies focused on changing levels of Ca2+ and TGFs are promising for treating muscle-wasting disorders. Three principal systems govern the homeostasis of Ca2+, namely, excitation-contraction (EC) coupling, excitation-coupled Ca2+ entry (ECCE), and store-operated Ca2+ entry (SOCE). Accordingly, alterations in these systems can lead to weakness and atrophy in many hereditary diseases, such as Brody disease, central core disease (CCD), tubular aggregate myopathy (TAM), myotonic dystrophy type 1 (MD1), oculopharyngeal muscular dystrophy (OPMD), and Duchenne muscular dystrophy (DMD). Here, the interrelationship between all these molecules and processes is reviewed.
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61
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Limpitikul W, Ong CS, Tomaselli GF. Neuromuscular Disease: Cardiac Manifestations and Sudden Death Risk. Card Electrophysiol Clin 2017; 9:731-747. [PMID: 29173414 DOI: 10.1016/j.ccep.2017.07.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Cardiovascular complications of neuromuscular diseases disproportionately affect the cardiac conduction system. Cardiomyopathy and cardiac arrhythmias produce significant morbidity and mortality. Patients with neuromuscular diseases should be carefully and frequently evaluated for the presence of bradycardia, heart block, and tachyarrhythmias. Preemptive treatment with permanent pacemakers or implanted defibrillators is appropriate in patients with conduction system disease or who are at risk for ventricular arrhythmias.
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Affiliation(s)
- Worawan Limpitikul
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, USA
| | - Chin Siang Ong
- Department of Medicine, Division of Cardiology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Gordon F Tomaselli
- Department of Medicine, Division of Cardiology, Johns Hopkins University School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA.
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62
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Abstract
Muscleblind-like (MBNL) proteins bind to hundreds of pre- and mature mRNAs to regulate their alternative splicing, alternative polyadenylation, stability and subcellular localization. Once MBNLs are withheld from transcript regulation, cellular machineries generate products inapt for precise embryonal/adult developmental tasks and myotonic dystrophy, a devastating multi-systemic genetic disorder, develops. We have recently demonstrated that all three MBNL paralogs are capable of fine-tuning cellular content of one of the three MBNL paralogs, MBNL1, by binding to the first coding exon (e1) of its pre-mRNA. Intriguingly, this autoregulatory feedback loop grounded on alternative splicing of e1 appears to play a crucial role in delaying the onset of myotonic dystrophy. Here, we describe this process in the context of other autoregulatory and regulatory loops that maintain the content and diverse functions of MBNL proteins at optimal level in health and disease, thus supporting the overall cellular homeostasis.
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Affiliation(s)
- Patryk Konieczny
- a Department of Gene Expression , Institute of Molecular Biology and Biotechnology, Adam Mickiewicz University , Poland
| | - Ewa Stepniak-Konieczna
- a Department of Gene Expression , Institute of Molecular Biology and Biotechnology, Adam Mickiewicz University , Poland
| | - Krzysztof Sobczak
- a Department of Gene Expression , Institute of Molecular Biology and Biotechnology, Adam Mickiewicz University , Poland
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Nakamori M, Hamanaka K, Thomas JD, Wang ET, Hayashi YK, Takahashi MP, Swanson MS, Nishino I, Mochizuki H. Aberrant Myokine Signaling in Congenital Myotonic Dystrophy. Cell Rep 2017; 21:1240-1252. [PMID: 29091763 PMCID: PMC5689469 DOI: 10.1016/j.celrep.2017.10.018] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Revised: 09/02/2017] [Accepted: 10/04/2017] [Indexed: 02/07/2023] Open
Abstract
Myotonic dystrophy types 1 (DM1) and 2 (DM2) are dominantly inherited neuromuscular disorders caused by a toxic gain of function of expanded CUG and CCUG repeats, respectively. Although both disorders are clinically similar, congenital myotonic dystrophy (CDM), a severe DM form, is found only in DM1. CDM is also characterized by muscle fiber immaturity not observed in adult DM, suggesting specific pathological mechanisms. Here, we revealed upregulation of the interleukin-6 (IL-6) myokine signaling pathway in CDM muscles. We also found a correlation between muscle immaturity and not only IL-6 expression but also expanded CTG repeat length and CpG methylation status upstream of the repeats. Aberrant CpG methylation was associated with transcriptional dysregulation at the repeat locus, increasing the toxic RNA burden that upregulates IL-6. Because the IL-6 pathway is involved in myocyte maturation and muscle atrophy, our results indicate that enhanced RNA toxicity contributes to severe CDM phenotypes through aberrant IL-6 signaling.
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Affiliation(s)
- Masayuki Nakamori
- Department of Neurology, Osaka University Graduate School of Medicine, Suita, Osaka 565-0871, Japan.
| | - Kohei Hamanaka
- Department of Neuromuscular Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Kodaira, Tokyo 187-8502, Japan
| | - James D Thomas
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics and the Genetics Institute, University of Florida, College of Medicine, Gainesville, FL 32610, USA
| | - Eric T Wang
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics and the Genetics Institute, University of Florida, College of Medicine, Gainesville, FL 32610, USA
| | - Yukiko K Hayashi
- Department of Pathophysiology, Tokyo Medical University, Shinjuku, Tokyo 160-0022, Japan
| | - Masanori P Takahashi
- Department of Neurology, Osaka University Graduate School of Medicine, Suita, Osaka 565-0871, Japan; Department of Functional Diagnostic Science, Osaka University Graduate School of Medicine, Suita, Osaka 565-0871, Japan
| | - Maurice S Swanson
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics and the Genetics Institute, University of Florida, College of Medicine, Gainesville, FL 32610, USA
| | - Ichizo Nishino
- Department of Neuromuscular Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Kodaira, Tokyo 187-8502, Japan
| | - Hideki Mochizuki
- Department of Neurology, Osaka University Graduate School of Medicine, Suita, Osaka 565-0871, Japan
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64
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Ravel-Chapuis A, Bélanger G, Côté J, Michel RN, Jasmin BJ. Misregulation of calcium-handling proteins promotes hyperactivation of calcineurin-NFAT signaling in skeletal muscle of DM1 mice. Hum Mol Genet 2017; 26:2192-2206. [PMID: 28369518 DOI: 10.1093/hmg/ddx109] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Accepted: 03/16/2017] [Indexed: 12/26/2022] Open
Abstract
Myotonic Dystrophy type 1 (DM1) is caused by an expansion of CUG repeats in DMPK mRNAs. This mutation affects alternative splicing through misregulation of RNA-binding proteins. Amongst pre-mRNAs that are mis-spliced, several code for proteins involved in calcium homeostasis suggesting that calcium-handling and signaling are perturbed in DM1. Here, we analyzed expression of such proteins in DM1 mouse muscle. We found that the levels of several sarcoplasmic reticulum proteins (SERCA1, sarcolipin and calsequestrin) are altered, likely contributing to an imbalance in calcium homeostasis. We also observed that calcineurin (CnA) signaling is hyperactivated in DM1 muscle. Indeed, CnA expression and phosphatase activity are both markedly increased in DM1 muscle. Coherent with this, we found that activators of the CnA pathway (MLP, FHL1) are also elevated. Consequently, NFATc1 expression is increased in DM1 muscle and becomes relocalized to myonuclei, together with an up-regulation of its transcriptional targets (RCAN1.4 and myoglobin). Accordingly, DM1 mouse muscles display an increase in oxidative metabolism and fiber hypertrophy. To determine the functional consequences of this CnA hyperactivation, we administered cyclosporine A, an inhibitor of CnA, to DM1 mice. Muscles of treated DM1 mice showed an increase in CUGBP1 levels, and an exacerbation of key alternative splicing events associated with DM1. Finally, inhibition of CnA in cultured human DM1 myoblasts also resulted in a splicing exacerbation of the insulin receptor. Together, these findings show for the first time that calcium-CnA signaling is hyperactivated in DM1 muscle and that such hyperactivation represents a beneficial compensatory adaptation to the disease.
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Affiliation(s)
- Aymeric Ravel-Chapuis
- Department of Cellular and Molecular Medicine and Center for Neuromuscular Disease, Faculty of Medicine, University of Ottawa, Ottawa, ON, Canada
| | - Guy Bélanger
- Department of Cellular and Molecular Medicine and Center for Neuromuscular Disease, Faculty of Medicine, University of Ottawa, Ottawa, ON, Canada
| | - Jocelyn Côté
- Department of Cellular and Molecular Medicine and Center for Neuromuscular Disease, Faculty of Medicine, University of Ottawa, Ottawa, ON, Canada
| | - Robin N Michel
- Department of Exercise Science, Faculty of Arts and Science, Concordia University, Montreal, QC, Canada
| | - Bernard J Jasmin
- Department of Cellular and Molecular Medicine and Center for Neuromuscular Disease, Faculty of Medicine, University of Ottawa, Ottawa, ON, Canada
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65
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Flucher BE, Tuluc P. How and why are calcium currents curtailed in the skeletal muscle voltage-gated calcium channels? J Physiol 2017; 595:1451-1463. [PMID: 27896815 PMCID: PMC5330888 DOI: 10.1113/jp273423] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Accepted: 11/24/2016] [Indexed: 01/09/2023] Open
Abstract
Voltage‐gated calcium channels represent the sole mechanism converting electrical signals of excitable cells into cellular functions such as contraction, secretion and gene regulation. Specific voltage‐sensing domains detect changes in membrane potential and control channel gating. Calcium ions entering through the channel function as second messengers regulating cell functions, with the exception of skeletal muscle, where CaV1.1 essentially does not function as a channel but activates calcium release from intracellular stores. It has long been known that calcium currents are dispensable for skeletal muscle contraction. However, the questions as to how and why the channel function of CaV1.1 is curtailed remained obscure until the recent discovery of a developmental CaV1.1 splice variant with normal channel functions. This discovery provided new means to study the molecular mechanisms regulating the channel gating and led to the understanding that in skeletal muscle, calcium currents need to be restricted to allow proper regulation of fibre type specification and to prevent mitochondrial damage.
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Affiliation(s)
- Bernhard E Flucher
- Department of Physiology and Medical Physics, Medical University Innsbruck, Austria
| | - Petronel Tuluc
- Pharmacology and Toxicology, Institute of Pharmacy, University of Innsbruck, Austria
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66
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Konieczny P, Stepniak-Konieczna E, Taylor K, Sznajder LJ, Sobczak K. Autoregulation of MBNL1 function by exon 1 exclusion from MBNL1 transcript. Nucleic Acids Res 2017; 45:1760-1775. [PMID: 27903900 PMCID: PMC5389549 DOI: 10.1093/nar/gkw1158] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2015] [Accepted: 11/07/2016] [Indexed: 01/14/2023] Open
Abstract
Muscleblind-like proteins (MBNLs) are regulators of RNA metabolism. During tissue differentiation the level of MBNLs increases, while their functional insufficiency plays a crucial role in myotonic dystrophy (DM). Deep sequencing of RNA molecules cross-linked to immunoprecipitated protein particles (CLIP-seq) revealed that MBNL1 binds to MBNL1 exon 1 (e1) encoding both the major part of 5΄UTR and an amino-terminal region of MBNL1 protein. We tested several hypotheses regarding the possible autoregulatory function of MBNL1 binding to its own transcript. Our data indicate that MBNLs induce skipping of e1 from precursor MBNL1 mRNA and that e1 exclusion may impact transcript association with polysomes and translation. Furthermore, e1-deficient protein isoform lacking the first two zinc fingers is highly unstable and its EGFP fusion protein has severely compromised splicing activity. We also show that MBNL1 can be transcribed from three different promoters and that the transcription initiation site determines the mode of e1 regulation. Taken together, we demonstrate that MBNL proteins control steady-state levels of MBNL1 through an interaction with e1 in its precursor mRNA. Insights from our study open a new avenue in therapies against DM based on manipulation of the transcription initiation site and e1 splicing of MBNL1 mRNA.
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Affiliation(s)
- Patryk Konieczny
- Department of Gene Expression, Institute of Molecular Biology and Biotechnology, Adam Mickiewicz University, Umultowska 89, 61-614 Poznan, Poland
| | - Ewa Stepniak-Konieczna
- Department of Gene Expression, Institute of Molecular Biology and Biotechnology, Adam Mickiewicz University, Umultowska 89, 61-614 Poznan, Poland
| | - Katarzyna Taylor
- Department of Gene Expression, Institute of Molecular Biology and Biotechnology, Adam Mickiewicz University, Umultowska 89, 61-614 Poznan, Poland
| | - Lukasz J Sznajder
- Department of Gene Expression, Institute of Molecular Biology and Biotechnology, Adam Mickiewicz University, Umultowska 89, 61-614 Poznan, Poland
| | - Krzysztof Sobczak
- Department of Gene Expression, Institute of Molecular Biology and Biotechnology, Adam Mickiewicz University, Umultowska 89, 61-614 Poznan, Poland
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67
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Feingold B, Mahle WT, Auerbach S, Clemens P, Domenighetti AA, Jefferies JL, Judge DP, Lal AK, Markham LW, Parks WJ, Tsuda T, Wang PJ, Yoo SJ. Management of Cardiac Involvement Associated With Neuromuscular Diseases: A Scientific Statement From the American Heart Association. Circulation 2017; 136:e200-e231. [DOI: 10.1161/cir.0000000000000526] [Citation(s) in RCA: 145] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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68
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Dysregulation of mRNA Localization and Translation in Genetic Disease. J Neurosci 2017; 36:11418-11426. [PMID: 27911744 DOI: 10.1523/jneurosci.2352-16.2016] [Citation(s) in RCA: 70] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Revised: 09/01/2016] [Accepted: 09/02/2016] [Indexed: 11/21/2022] Open
Abstract
RNA-binding proteins (RBPs) acting at various steps in the post-transcriptional regulation of gene expression play crucial roles in neuronal development and synaptic plasticity. Genetic mutations affecting several RBPs and associated factors lead to diverse neurological symptoms, as characterized by neurodevelopmental and neuropsychiatric disorders, neuromuscular and neurodegenerative diseases, and can often be multisystemic diseases. We will highlight the physiological roles of a few specific proteins in molecular mechanisms of cytoplasmic mRNA regulation, and how these processes are dysregulated in genetic disease. Recent advances in computational biology and genomewide analysis, integrated with diverse experimental approaches and model systems, have provided new insights into conserved mechanisms and the shared pathobiology of mRNA dysregulation in disease. Progress has been made to understand the pathobiology of disease mechanisms for myotonic dystrophy, spinal muscular atrophy, and fragile X syndrome, with broader implications for other RBP-associated genetic neurological diseases. This gained knowledge of underlying basic mechanisms has paved the way to the development of therapeutic strategies targeting disease mechanisms.
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69
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Seitter H, Koschak A. Relevance of tissue specific subunit expression in channelopathies. Neuropharmacology 2017; 132:58-70. [PMID: 28669898 DOI: 10.1016/j.neuropharm.2017.06.029] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Revised: 06/22/2017] [Accepted: 06/28/2017] [Indexed: 12/27/2022]
Abstract
Channelopathies are a diverse group of human disorders that are caused by mutations in genes coding for ion channels or channel-regulating proteins. Several dozen channelopathies have been identified that involve both non-excitable cells as well as electrically active tissues like brain, skeletal and smooth muscle or the heart. In this review, we start out from the general question which ion channel genes are expressed tissue-selectively. We mined the human gene expression database Human Protein Atlas (HPA) for tissue-enriched ion channel genes and found 85 genes belonging to the ion channel families. Most of these genes were enriched in brain, testis and muscle and a complete list of the enriched ion channel genes is provided. We further focused on the tissue distribution of voltage-gated calcium channel (VGCC) genes including different brain areas and the retina based on the human gene expression from the FANTOM5 dataset. The expression data is complemented by an overview of the tissue-dependent aspects of L-type calcium channel (LTCC) function, dysfunction and pharmacology, as well as of their splice variants. Finally, we focus on the pathology of tissue-restricted LTCC channelopathies and their treatment options. This article is part of the Special Issue entitled 'Channelopathies.'
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Affiliation(s)
- Hartwig Seitter
- University of Innsbruck, Institute of Pharmacy, Pharmacology and Toxicology, Center for Chemistry and Biomedicine, Innrain 80-82/III, 6020 Innsbruck, Austria
| | - Alexandra Koschak
- University of Innsbruck, Institute of Pharmacy, Pharmacology and Toxicology, Center for Chemistry and Biomedicine, Innrain 80-82/III, 6020 Innsbruck, Austria.
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70
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Yenigun VB, Sirito M, Amcheslavky A, Czernuszewicz T, Colonques-Bellmunt J, García-Alcover I, Wojciechowska M, Bolduc C, Chen Z, López Castel A, Krahe R, Bergmann A. (CCUG) n RNA toxicity in a Drosophila model of myotonic dystrophy type 2 (DM2) activates apoptosis. Dis Model Mech 2017. [PMID: 28623239 PMCID: PMC5560059 DOI: 10.1242/dmm.026179] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The myotonic dystrophies are prototypic toxic RNA gain-of-function diseases. Myotonic dystrophy type 1 (DM1) and type 2 (DM2) are caused by different unstable, noncoding microsatellite repeat expansions – (CTG)DM1 in DMPK and (CCTG)DM2 in CNBP. Although transcription of mutant repeats into (CUG)DM1 or (CCUG)DM2 appears to be necessary and sufficient to cause disease, their pathomechanisms remain incompletely understood. To study the mechanisms of (CCUG)DM2 toxicity and develop a convenient model for drug screening, we generated a transgenic DM2 model in the fruit fly Drosophila melanogaster with (CCUG)n repeats of variable length (n=16 and 106). Expression of noncoding (CCUG)106, but not (CCUG)16, in muscle and retinal cells led to the formation of ribonuclear foci and mis-splicing of genes implicated in DM pathology. Mis-splicing could be rescued by co-expression of human MBNL1, but not by CUGBP1 (CELF1) complementation. Flies with (CCUG)106 displayed strong disruption of external eye morphology and of the underlying retina. Furthermore, expression of (CCUG)106 in developing retinae caused a strong apoptotic response. Inhibition of apoptosis rescued the retinal disruption in (CCUG)106 flies. Finally, we tested two chemical compounds that have shown therapeutic potential in DM1 models. Whereas treatment of (CCUG)106 flies with pentamidine had no effect, treatment with a PKR inhibitor blocked both the formation of RNA foci and apoptosis in retinae of (CCUG)106 flies. Our data indicate that expression of expanded (CCUG)DM2 repeats is toxic, causing inappropriate cell death in affected fly eyes. Our Drosophila DM2 model might provide a convenient tool for in vivo drug screening. Summary: A Drosophila model of myotonic dystrophy type 2 (DM2) recapitulates several features of the human disease, identifies apoptosis as a contributing factor to DM2, and is likely to provide a convenient tool for drug screening.
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Affiliation(s)
- Vildan Betul Yenigun
- Department of Biochemistry & Molecular Biology, University of Texas MD Anderson Cancer Center, Houston, TX, USA.,Departments of Genetics, University of Texas MD Anderson Cancer Center, Houston, TX, USA.,Graduate Programs in Genes & Development, University of Texas Graduate School in Biomedical Sciences at Houston, Houston, TX, USA
| | - Mario Sirito
- Departments of Genetics, University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Alla Amcheslavky
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Tomek Czernuszewicz
- Departments of Genetics, University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | | | | | - Marzena Wojciechowska
- Departments of Genetics, University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Clare Bolduc
- Department of Biochemistry & Molecular Biology, University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Zhihong Chen
- Department of Biochemistry & Molecular Biology, University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | | | - Ralf Krahe
- Departments of Genetics, University of Texas MD Anderson Cancer Center, Houston, TX, USA .,Graduate Programs in Genes & Development, University of Texas Graduate School in Biomedical Sciences at Houston, Houston, TX, USA.,Graduate Programs in Human & Molecular Genetics, University of Texas Graduate School in Biomedical Sciences at Houston, Houston, Texas, USA
| | - Andreas Bergmann
- Department of Biochemistry & Molecular Biology, University of Texas MD Anderson Cancer Center, Houston, TX, USA .,Graduate Programs in Genes & Development, University of Texas Graduate School in Biomedical Sciences at Houston, Houston, TX, USA.,Department of Molecular, Cell and Cancer Biology, University of Massachusetts Medical School, Worcester, MA, USA
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71
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Expanded CCUG repeat RNA expression in Drosophila heart and muscle trigger Myotonic Dystrophy type 1-like phenotypes and activate autophagocytosis genes. Sci Rep 2017; 7:2843. [PMID: 28588248 PMCID: PMC5460254 DOI: 10.1038/s41598-017-02829-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Accepted: 04/19/2017] [Indexed: 12/12/2022] Open
Abstract
Myotonic dystrophies (DM1–2) are neuromuscular genetic disorders caused by the pathological expansion of untranslated microsatellites. DM1 and DM2, are caused by expanded CTG repeats in the 3′UTR of the DMPK gene and CCTG repeats in the first intron of the CNBP gene, respectively. Mutant RNAs containing expanded repeats are retained in the cell nucleus, where they sequester nuclear factors and cause alterations in RNA metabolism. However, for unknown reasons, DM1 is more severe than DM2. To study the differences and similarities in the pathogenesis of DM1 and DM2, we generated model flies by expressing pure expanded CUG ([250]×) or CCUG ([1100]×) repeats, respectively, and compared them with control flies expressing either 20 repeat units or GFP. We observed surprisingly severe muscle reduction and cardiac dysfunction in CCUG-expressing model flies. The muscle and cardiac tissue of both DM1 and DM2 model flies showed DM1-like phenotypes including overexpression of autophagy-related genes, RNA mis-splicing and repeat RNA aggregation in ribonuclear foci along with the Muscleblind protein. These data reveal, for the first time, that expanded non-coding CCUG repeat-RNA has similar in vivo toxicity potential as expanded CUG RNA in muscle and heart tissues and suggests that specific, as yet unknown factors, quench CCUG-repeat toxicity in DM2 patients.
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72
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Schartner V, Romero NB, Donkervoort S, Treves S, Munot P, Pierson TM, Dabaj I, Malfatti E, Zaharieva IT, Zorzato F, Abath Neto O, Brochier G, Lornage X, Eymard B, Taratuto AL, Böhm J, Gonorazky H, Ramos-Platt L, Feng L, Phadke R, Bharucha-Goebel DX, Sumner CJ, Bui MT, Lacene E, Beuvin M, Labasse C, Dondaine N, Schneider R, Thompson J, Boland A, Deleuze JF, Matthews E, Pakleza AN, Sewry CA, Biancalana V, Quijano-Roy S, Muntoni F, Fardeau M, Bönnemann CG, Laporte J. Dihydropyridine receptor (DHPR, CACNA1S) congenital myopathy. Acta Neuropathol 2017; 133:517-533. [PMID: 28012042 DOI: 10.1007/s00401-016-1656-8] [Citation(s) in RCA: 74] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2016] [Revised: 12/09/2016] [Accepted: 12/11/2016] [Indexed: 10/20/2022]
Abstract
Muscle contraction upon nerve stimulation relies on excitation-contraction coupling (ECC) to promote the rapid and generalized release of calcium within myofibers. In skeletal muscle, ECC is performed by the direct coupling of a voltage-gated L-type Ca2+ channel (dihydropyridine receptor; DHPR) located on the T-tubule with a Ca2+ release channel (ryanodine receptor; RYR1) on the sarcoplasmic reticulum (SR) component of the triad. Here, we characterize a novel class of congenital myopathy at the morphological, molecular, and functional levels. We describe a cohort of 11 patients from 7 families presenting with perinatal hypotonia, severe axial and generalized weakness. Ophthalmoplegia is present in four patients. The analysis of muscle biopsies demonstrated a characteristic intermyofibrillar network due to SR dilatation, internal nuclei, and areas of myofibrillar disorganization in some samples. Exome sequencing revealed ten recessive or dominant mutations in CACNA1S (Cav1.1), the pore-forming subunit of DHPR in skeletal muscle. Both recessive and dominant mutations correlated with a consistent phenotype, a decrease in protein level, and with a major impairment of Ca2+ release induced by depolarization in cultured myotubes. While dominant CACNA1S mutations were previously linked to malignant hyperthermia susceptibility or hypokalemic periodic paralysis, our findings strengthen the importance of DHPR for perinatal muscle function in human. These data also highlight CACNA1S and ECC as therapeutic targets for the development of treatments that may be facilitated by the previous knowledge accumulated on DHPR.
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73
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Esposito F, Cè E, Rampichini S, Monti E, Limonta E, Fossati B, Meola G. Electromechanical delays during a fatiguing exercise and recovery in patients with myotonic dystrophy type 1. Eur J Appl Physiol 2017; 117:551-566. [PMID: 28194519 DOI: 10.1007/s00421-017-3558-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Accepted: 01/24/2017] [Indexed: 01/08/2023]
Abstract
PURPOSE The partitioning of the electromechanical delay by an electromyographic (EMG), mechanomyographic (MMG) and force combined approach can provide further insight into the electrochemical and mechanical processes involved with skeletal muscle contraction and relaxation. The aim of the study was to monitor by this combined approach the changes in delays' electrochemical and mechanical components throughout a fatiguing task and during recovery in patients with myotonic dystrophy type 1 (DM1), who present at the skeletal muscle level fibres rearrangement, muscle weakness and myotonia, especially in the distal muscles. METHODS After assessing maximum voluntary contraction (MVC), 14 male patients with DM1 and 14 healthy controls (HC) performed a fatiguing exercise at 50% MVC until exhaustion. EMG, MMG, and force signals were recorded from tibialis anterior and vastus lateralis muscles. The electromechanical delay during contraction (DelayTOT) and relaxation (R-DelayTOT) components, EMG and MMG root mean square (RMS) and mean frequency (MF) were calculated off-line. RESULTS The fatiguing exercise duration was similar in both groups. In patients with DM1, delays components were significantly longer compared to HC, especially in the distal muscle during relaxation. Delays components recovered quickly from the fatiguing exercise in HC than in patients with DM1 in both muscles. CONCLUSIONS The alterations in delays observed in DM1 during the fatiguing exercise may indicate that also the lengthening of the electrochemical and mechanical processes during contraction and relaxation could play a role in explaining exercise intolerance in this pathology.
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Affiliation(s)
- Fabio Esposito
- Department of Biomedical Sciences for Health (SCIBIS), Università degli Studi di Milano, Via G. Colombo 71, 20133, Milan, Italy. .,IRCCS Fondazione don Gnocchi, Centro di Medicina dello Sport, via Capecelatro 66, 20148, Milan, Italy.
| | - Emiliano Cè
- Department of Biomedical Sciences for Health (SCIBIS), Università degli Studi di Milano, Via G. Colombo 71, 20133, Milan, Italy
| | - Susanna Rampichini
- Department of Biomedical Sciences for Health (SCIBIS), Università degli Studi di Milano, Via G. Colombo 71, 20133, Milan, Italy
| | - Elena Monti
- Department of Biomedical Sciences for Health (SCIBIS), Università degli Studi di Milano, Via G. Colombo 71, 20133, Milan, Italy
| | - Eloisa Limonta
- Department of Biomedical Sciences for Health (SCIBIS), Università degli Studi di Milano, Via G. Colombo 71, 20133, Milan, Italy
| | - Barbara Fossati
- IRCCS Policlinico San Donato, Piazza Malan 2, 20097, San Donato Milanese (MI), Italy
| | - Giovanni Meola
- Department of Biomedical Sciences for Health (SCIBIS), Università degli Studi di Milano, Via G. Colombo 71, 20133, Milan, Italy.,IRCCS Policlinico San Donato, Piazza Malan 2, 20097, San Donato Milanese (MI), Italy
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74
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Lee MY, Park C, Ha SE, Park PJ, Berent RM, Jorgensen BG, Corrigan RD, Grainger N, Blair PJ, Slivano OJ, Miano JM, Ward SM, Smith TK, Sanders KM, Ro S. Serum response factor regulates smooth muscle contractility via myotonic dystrophy protein kinases and L-type calcium channels. PLoS One 2017; 12:e0171262. [PMID: 28152551 PMCID: PMC5289827 DOI: 10.1371/journal.pone.0171262] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Accepted: 01/17/2017] [Indexed: 11/19/2022] Open
Abstract
Serum response factor (SRF) transcriptionally regulates expression of contractile genes in smooth muscle cells (SMC). Lack or decrease of SRF is directly linked to a phenotypic change of SMC, leading to hypomotility of smooth muscle in the gastrointestinal (GI) tract. However, the molecular mechanism behind SRF-induced hypomotility in GI smooth muscle is largely unknown. We describe here how SRF plays a functional role in the regulation of the SMC contractility via myotonic dystrophy protein kinase (DMPK) and L-type calcium channel CACNA1C. GI SMC expressed Dmpk and Cacna1c genes into multiple alternative transcriptional isoforms. Deficiency of SRF in SMC of Srf knockout (KO) mice led to reduction of SRF-dependent DMPK, which down-regulated the expression of CACNA1C. Reduction of CACNA1C in KO SMC not only decreased intracellular Ca2+ spikes but also disrupted their coupling between cells resulting in decreased contractility. The role of SRF in the regulation of SMC phenotype and function provides new insight into how SMC lose their contractility leading to hypomotility in pathophysiological conditions within the GI tract.
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Affiliation(s)
- Moon Young Lee
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada, United States of America
- Department of Physiology, Wonkwang Digestive Disease Research Institute and Institute of Wonkwang Medical Science, School of Medicine, Wonkwang University, Iksan, Chonbuk, Korea
| | - Chanjae Park
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada, United States of America
| | - Se Eun Ha
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada, United States of America
| | - Paul J. Park
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada, United States of America
| | - Robyn M. Berent
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada, United States of America
| | - Brian G. Jorgensen
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada, United States of America
| | - Robert D. Corrigan
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada, United States of America
| | - Nathan Grainger
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada, United States of America
| | - Peter J. Blair
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada, United States of America
| | - Orazio J. Slivano
- Aab Cardiovascular Research Institute, University of Rochester School of Medicine and Dentistry, Rochester, New York, United States of America
| | - Joseph M. Miano
- Aab Cardiovascular Research Institute, University of Rochester School of Medicine and Dentistry, Rochester, New York, United States of America
| | - Sean M. Ward
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada, United States of America
| | - Terence K. Smith
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada, United States of America
| | - Kenton M. Sanders
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada, United States of America
| | - Seungil Ro
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada, United States of America
- * E-mail:
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75
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Meola G, Cardani R. Myotonic dystrophy type 2 and modifier genes: an update on clinical and pathomolecular aspects. Neurol Sci 2017; 38:535-546. [PMID: 28078562 DOI: 10.1007/s10072-016-2805-5] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2016] [Accepted: 12/22/2016] [Indexed: 12/20/2022]
Abstract
Myotonic dystrophy (DM) is the most common adult muscular dystrophy, characterized by autosomal dominant progressive myopathy, myotonia, and multiorgan involvement. To date, two distinct forms caused by similar mutations in two different genes have been identified: myotonic dystrophy type 1 (DM1) and myotonic dystrophy type 2 (DM2). Aberrant transcription and mRNA processing of multiple genes due to RNA-mediated toxic gain-of function has been suggested to cause the complex phenotype in DM1 and DM2. However, despite clinical and genetic similarities, DM1 and DM2 may be considered as distinct disorders. This review is an update on the latest findings specific to DM2, including explanations for the differences in clinical manifestations and pathophysiology between the two forms of myotonic dystrophies.
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Affiliation(s)
- Giovanni Meola
- Department of Biomedical Sciences for Health, University of Milan, IRCCS Policlinico San Donato, Piazza E. Malan, 1, San Donato Mil., 20097, Milan, Italy. .,Department of Neurology, IRCCS Policlinico San Donato, San Donato Milanese, Milan, Italy.
| | - Rosanna Cardani
- Laboratory of Muscle Histopathology and Molecular Biology, IRCCS Policlinico San Donato, San Donato Milanese, Milan, Italy
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76
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Brockhoff M, Rion N, Chojnowska K, Wiktorowicz T, Eickhorst C, Erne B, Frank S, Angelini C, Furling D, Rüegg MA, Sinnreich M, Castets P. Targeting deregulated AMPK/mTORC1 pathways improves muscle function in myotonic dystrophy type I. J Clin Invest 2017; 127:549-563. [PMID: 28067669 DOI: 10.1172/jci89616] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Accepted: 11/17/2016] [Indexed: 12/13/2022] Open
Abstract
Myotonic dystrophy type I (DM1) is a disabling multisystemic disease that predominantly affects skeletal muscle. It is caused by expanded CTG repeats in the 3'-UTR of the dystrophia myotonica protein kinase (DMPK) gene. RNA hairpins formed by elongated DMPK transcripts sequester RNA-binding proteins, leading to mis-splicing of numerous pre-mRNAs. Here, we have investigated whether DM1-associated muscle pathology is related to deregulation of central metabolic pathways, which may identify potential therapeutic targets for the disease. In a well-characterized mouse model for DM1 (HSALR mice), activation of AMPK signaling in muscle was impaired under starved conditions, while mTORC1 signaling remained active. In parallel, autophagic flux was perturbed in HSALR muscle and in cultured human DM1 myotubes. Pharmacological approaches targeting AMPK/mTORC1 signaling greatly ameliorated muscle function in HSALR mice. AICAR, an AMPK activator, led to a strong reduction of myotonia, which was accompanied by partial correction of misregulated alternative splicing. Rapamycin, an mTORC1 inhibitor, improved muscle relaxation and increased muscle force in HSALR mice without affecting splicing. These findings highlight the involvement of AMPK/mTORC1 deregulation in DM1 muscle pathophysiology and may open potential avenues for the treatment of this disease.
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77
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Tajhya RB, Hu X, Tanner MR, Huq R, Kongchan N, Neilson JR, Rodney GG, Horrigan FT, Timchenko LT, Beeton C. Functional KCa1.1 channels are crucial for regulating the proliferation, migration and differentiation of human primary skeletal myoblasts. Cell Death Dis 2016; 7:e2426. [PMID: 27763639 PMCID: PMC5133989 DOI: 10.1038/cddis.2016.324] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Revised: 09/14/2016] [Accepted: 09/15/2016] [Indexed: 01/14/2023]
Abstract
Myoblasts are mononucleated precursors of myofibers; they persist in mature skeletal muscles for growth and regeneration post injury. During myotonic dystrophy type 1 (DM1), a complex autosomal-dominant neuromuscular disease, the differentiation of skeletal myoblasts into functional myotubes is impaired, resulting in muscle wasting and weakness. The mechanisms leading to this altered differentiation are not fully understood. Here, we demonstrate that the calcium- and voltage-dependent potassium channel, KCa1.1 (BK, Slo1, KCNMA1), regulates myoblast proliferation, migration, and fusion. We also show a loss of plasma membrane expression of the pore-forming α subunit of KCa1.1 in DM1 myoblasts. Inhibiting the function of KCa1.1 in healthy myoblasts induced an increase in cytosolic calcium levels and altered nuclear factor kappa B (NFκB) levels without affecting cell survival. In these normal cells, KCa1.1 block resulted in enhanced proliferation and decreased matrix metalloproteinase secretion, migration, and myotube fusion, phenotypes all observed in DM1 myoblasts and associated with disease pathogenesis. In contrast, introducing functional KCa1.1 α-subunits into DM1 myoblasts normalized their proliferation and rescued expression of the late myogenic marker Mef2. Our results identify KCa1.1 channels as crucial regulators of skeletal myogenesis and suggest these channels as novel therapeutic targets in DM1.
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Affiliation(s)
- Rajeev B Tajhya
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX 77030, USA.,Graduate Program in Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX 77030, USA.,Cardiovascular Research Institute, Baylor College of Medicine, Houston, TX 77030, USA
| | - Xueyou Hu
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Mark R Tanner
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX 77030, USA.,Interdepartmental Graduate Program in Translational Biology and Molecular Medicine, Baylor College of Medicine, Houston, TX 77030, USA
| | - Redwan Huq
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX 77030, USA.,Graduate Program in Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Natee Kongchan
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Joel R Neilson
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX 77030, USA.,Cardiovascular Research Institute, Baylor College of Medicine, Houston, TX 77030, USA
| | - George G Rodney
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX 77030, USA.,Cardiovascular Research Institute, Baylor College of Medicine, Houston, TX 77030, USA
| | - Frank T Horrigan
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX 77030, USA.,Cardiovascular Research Institute, Baylor College of Medicine, Houston, TX 77030, USA.,Center for Drug Discovery, Baylor College of Medicine, Houston, TX 77030, USA
| | - Lubov T Timchenko
- Department of Pediatrics Neurology, Cincinnati Children's Hospital, Cincinnati, OH 45219, USA
| | - Christine Beeton
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX 77030, USA.,Cardiovascular Research Institute, Baylor College of Medicine, Houston, TX 77030, USA.,Center for Drug Discovery, Baylor College of Medicine, Houston, TX 77030, USA.,Biology of Inflammation Center, Baylor College of Medicine, Houston, TX 77030, USA
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78
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Dose-Dependent Regulation of Alternative Splicing by MBNL Proteins Reveals Biomarkers for Myotonic Dystrophy. PLoS Genet 2016; 12:e1006316. [PMID: 27681373 PMCID: PMC5082313 DOI: 10.1371/journal.pgen.1006316] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Accepted: 08/23/2016] [Indexed: 01/23/2023] Open
Abstract
Alternative splicing is a regulated process that results in expression of
specific mRNA and protein isoforms. Alternative splicing factors determine the
relative abundance of each isoform. Here we focus on MBNL1, a splicing factor
misregulated in the disease myotonic dystrophy. By altering the concentration of
MBNL1 in cells across a broad dynamic range, we show that different splicing
events require different amounts of MBNL1 for half-maximal response, and respond
more or less steeply to MBNL1. Motifs around MBNL1 exon 5 were studied to assess
how cis-elements mediate the MBNL1 dose-dependent splicing
response. A framework was developed to estimate MBNL concentration using
splicing responses alone, validated in the cell-based model, and applied to
myotonic dystrophy patient muscle. Using this framework, we evaluated the
ability of individual and combinations of splicing events to predict functional
MBNL concentration in human biopsies, as well as their performance as biomarkers
to assay mild, moderate, and severe cases of DM. Our studies provide insight into the mechanisms of myotonic dystrophy, the most
common adult form of muscular dystrophy. In this disease, a family of RNA
binding proteins is sequestered by toxic RNA, which leads to mis-regulation and
disease symptoms. We have created a cellular model with one of these family
members to study how these RNA binding proteins function in the absence of the
toxic RNA. In parallel, we analyzed transcriptomic data from over 50 individuals
(44 affected by myotonic dystrophy) with a range of disease severity. The
results from the transcriptomic data provide a rational approach to select
biomarkers for clinical research and therapeutic trials.
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79
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Beqollari D, Romberg CF, Dobrowolny G, Martini M, Voss AA, Musarò A, Bannister RA. Progressive impairment of CaV1.1 function in the skeletal muscle of mice expressing a mutant type 1 Cu/Zn superoxide dismutase (G93A) linked to amyotrophic lateral sclerosis. Skelet Muscle 2016; 6:24. [PMID: 27340545 PMCID: PMC4918102 DOI: 10.1186/s13395-016-0094-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Accepted: 06/03/2016] [Indexed: 11/24/2022] Open
Abstract
Background Amyotrophic lateral sclerosis (ALS) is an adult-onset neurodegenerative disorder that is typically fatal within 3–5 years of diagnosis. While motoneuron death is the defining characteristic of ALS, the events that underlie its pathology are not restricted to the nervous system. In this regard, ALS muscle atrophies and weakens significantly before presentation of neurological symptoms. Since the skeletal muscle L-type Ca2+ channel (CaV1.1) is a key regulator of both mass and force, we investigated whether CaV1.1 function is impaired in the muscle of two distinct mouse models carrying an ALS-linked mutation. Methods We recorded L-type currents, charge movements, and myoplasmic Ca2+ transients from dissociated flexor digitorum brevis (FDB) fibers to assess CaV1.1 function in two mouse models expressing a type 1 Cu/Zn superoxide dismutase mutant (SOD1G93A). Results In FDB fibers obtained from “symptomatic” global SOD1G93A mice, we observed a substantial reduction of SR Ca2+ release in response to depolarization relative to fibers harvested from age-matched control mice. L-type current and charge movement were both reduced by ~40 % in symptomatic SOD1G93A fibers when compared to control fibers. Ca2+ transients were not significantly reduced in similar experiments performed with FDB fibers obtained from “early-symptomatic” SOD1G93A mice, but L-type current and charge movement were decreased (~30 and ~20 %, respectively). Reductions in SR Ca2+ release (~35 %), L-type current (~20 %), and charge movement (~15 %) were also observed in fibers obtained from another model where SOD1G93A expression was restricted to skeletal muscle. Conclusions We report reductions in EC coupling, L-type current density, and charge movement in FDB fibers obtained from symptomatic global SOD1G93A mice. Experiments performed with FDB fibers obtained from early-symptomatic SOD1G93A and skeletal muscle autonomous MLC/SOD1G93A mice support the idea that events occurring locally in the skeletal muscle contribute to the impairment of CaV1.1 function in ALS muscle independently of innervation status. Electronic supplementary material The online version of this article (doi:10.1186/s13395-016-0094-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Donald Beqollari
- Department of Medicine-Cardiology Division, University of Colorado School of Medicine, 12700 East 19th Avenue, B-139, Aurora, CO 80045 USA
| | - Christin F Romberg
- Department of Medicine-Cardiology Division, University of Colorado School of Medicine, 12700 East 19th Avenue, B-139, Aurora, CO 80045 USA
| | - Gabriella Dobrowolny
- Institute Pasteur Cenci-Bolognetti, DAHFMO-Unit of Histology and Medical Embryology, La Sapienza University, Via A. Scarpa, 14, 00161 Rome, Italy ; Center for Life Nano Science@Sapienza, Istituto Italiano di Tecnologia, Rome, Italy
| | - Martina Martini
- Institute Pasteur Cenci-Bolognetti, DAHFMO-Unit of Histology and Medical Embryology, La Sapienza University, Via A. Scarpa, 14, 00161 Rome, Italy ; Center for Life Nano Science@Sapienza, Istituto Italiano di Tecnologia, Rome, Italy
| | - Andrew A Voss
- Department of Biological Sciences, College of Science and Mathematics, Wright State University, 235A Biological Sciences, 3640 Colonel Glenn Highway, Dayton, OH 45435 USA
| | - Antonio Musarò
- Institute Pasteur Cenci-Bolognetti, DAHFMO-Unit of Histology and Medical Embryology, La Sapienza University, Via A. Scarpa, 14, 00161 Rome, Italy ; Center for Life Nano Science@Sapienza, Istituto Italiano di Tecnologia, Rome, Italy
| | - Roger A Bannister
- Department of Medicine-Cardiology Division, University of Colorado School of Medicine, 12700 East 19th Avenue, B-139, Aurora, CO 80045 USA
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80
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Tuluc P, Benedetti B, Coste de Bagneaux P, Grabner M, Flucher BE. Two distinct voltage-sensing domains control voltage sensitivity and kinetics of current activation in CaV1.1 calcium channels. J Gen Physiol 2016; 147:437-49. [PMID: 27185857 PMCID: PMC4886277 DOI: 10.1085/jgp.201611568] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Accepted: 04/18/2016] [Indexed: 01/25/2023] Open
Abstract
Alternative splicing of the skeletal muscle CaV1.1 voltage-gated calcium channel gives rise to two channel variants with very different gating properties. The currents of both channels activate slowly; however, insertion of exon 29 in the adult splice variant CaV1.1a causes an ∼30-mV right shift in the voltage dependence of activation. Existing evidence suggests that the S3-S4 linker in repeat IV (containing exon 29) regulates voltage sensitivity in this voltage-sensing domain (VSD) by modulating interactions between the adjacent transmembrane segments IVS3 and IVS4. However, activation kinetics are thought to be determined by corresponding structures in repeat I. Here, we use patch-clamp analysis of dysgenic (CaV1.1 null) myotubes reconstituted with CaV1.1 mutants and chimeras to identify the specific roles of these regions in regulating channel gating properties. Using site-directed mutagenesis, we demonstrate that the structure and/or hydrophobicity of the IVS3-S4 linker is critical for regulating voltage sensitivity in the IV VSD, but by itself cannot modulate voltage sensitivity in the I VSD. Swapping sequence domains between the I and the IV VSDs reveals that IVS4 plus the IVS3-S4 linker is sufficient to confer CaV1.1a-like voltage dependence to the I VSD and that the IS3-S4 linker plus IS4 is sufficient to transfer CaV1.1e-like voltage dependence to the IV VSD. Any mismatch of transmembrane helices S3 and S4 from the I and IV VSDs causes a right shift of voltage sensitivity, indicating that regulation of voltage sensitivity by the IVS3-S4 linker requires specific interaction of IVS4 with its corresponding IVS3 segment. In contrast, slow current kinetics are perturbed by any heterologous sequences inserted into the I VSD and cannot be transferred by moving VSD I sequences to VSD IV. Thus, CaV1.1 calcium channels are organized in a modular manner, and control of voltage sensitivity and activation kinetics is accomplished by specific molecular mechanisms within the IV and I VSDs, respectively.
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Affiliation(s)
- Petronel Tuluc
- Department of Pharmacology and Toxicology, Institute of Pharmacy, University of Innsbruck, A-6020 Innsbruck, Austria
| | - Bruno Benedetti
- Department of Physiology and Medical Physics, Medical University Innsbruck, A-6020 Innsbruck, Austria
| | - Pierre Coste de Bagneaux
- Department of Physiology and Medical Physics, Medical University Innsbruck, A-6020 Innsbruck, Austria
| | - Manfred Grabner
- Department of Medical Genetics, Molecular and Clinical Pharmacology, Medical University Innsbruck, A-6020 Innsbruck, Austria
| | - Bernhard E Flucher
- Department of Physiology and Medical Physics, Medical University Innsbruck, A-6020 Innsbruck, Austria
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81
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Splicing misregulation of SCN5A contributes to cardiac-conduction delay and heart arrhythmia in myotonic dystrophy. Nat Commun 2016; 7:11067. [PMID: 27063795 PMCID: PMC4831019 DOI: 10.1038/ncomms11067] [Citation(s) in RCA: 126] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Accepted: 02/16/2016] [Indexed: 12/11/2022] Open
Abstract
Myotonic dystrophy (DM) is caused by the expression of mutant RNAs containing expanded CUG repeats that sequester muscleblind-like (MBNL) proteins, leading to alternative splicing changes. Cardiac alterations, characterized by conduction delays and arrhythmia, are the second most common cause of death in DM. Using RNA sequencing, here we identify novel splicing alterations in DM heart samples, including a switch from adult exon 6B towards fetal exon 6A in the cardiac sodium channel, SCN5A. We find that MBNL1 regulates alternative splicing of SCN5A mRNA and that the splicing variant of SCN5A produced in DM presents a reduced excitability compared with the control adult isoform. Importantly, reproducing splicing alteration of Scn5a in mice is sufficient to promote heart arrhythmia and cardiac-conduction delay, two predominant features of myotonic dystrophy. In conclusion, misregulation of the alternative splicing of SCN5A may contribute to a subset of the cardiac dysfunctions observed in myotonic dystrophy. Patients with myotonic dystrophy (MD) suffer from severe cardiac issues of unknown aetiology. Freyermuth et al. show that fatal changes in cardiac electrophysiological properties in humans and mice with MD may arise from misregulation of the alternative splicing of the cardiac Na+ channel SCN5A transcript, resulting in expression of its fetal form.
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82
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Moshourab R, Palada V, Grunwald S, Grieben U, Lewin GR, Spuler S. A Molecular Signature of Myalgia in Myotonic Dystrophy 2. EBioMedicine 2016; 7:205-11. [PMID: 27322473 PMCID: PMC4909324 DOI: 10.1016/j.ebiom.2016.03.017] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Revised: 02/26/2016] [Accepted: 03/11/2016] [Indexed: 01/12/2023] Open
Abstract
Background Chronic muscle pain affects close to 20% of the population and is a major health burden. The underlying mechanisms of muscle pain are difficult to investigate as pain presents in patients with very diverse histories. Treatment options are therefore limited and not tailored to underlying mechanisms. To gain insight into the pathophysiology of myalgia we investigated a homogeneous group of patients suffering from myotonic dystrophy type 2 (DM2), a monogenic disorder presenting with myalgia in at least 50% of affected patients. Methods After IRB approval we performed an observational cross-sectional cohort study and recruited 42 patients with genetically confirmed DM2 plus 20 healthy age and gender matched control subjects. All participants were subjected to an extensive sensory-testing protocol. In addition, RNA sequencing was performed from 12 muscle biopsy specimens obtained from DM2 patients. Findings Clinical sensory testing as well as RNA sequencing clearly separated DM2 myalgic from non-myalgia patients and also from healthy controls. In particular pressure pain thresholds were significantly lowered for all muscles tested in myalgic DM2 patients but were not significantly different between non-myalgic patients and healthy controls. The expression of fourteen muscle expressed genes in myalgic patients was significantly up or down-regulated in myalgic compared to non-myalgic DM2 patients. Interpretation Our data support the idea that molecular changes in the muscles of DM2 patients are associated with muscle pain. Further studies should address whether muscle-specific molecular pathways play a significant role in myalgia in order to facilitate the development of mechanism-based therapeutic strategies to treat musculoskeletal pain. Funding This study was funded by the German Research Society (DFG, GK1631), KAP programme of Charité Universitätsmedizin Berlin and Max Delbrück Center for Molecular Medicine. Pressure pain thresholds were reduced in myotonic dystrophy 2 (DM2) and myalgias, but not in DM2 without myalgias RNASeq from skeletal muscle differed significantly in 14 genes between DM2 with myalgias and DM2 without myalgias
Patients with a rare type of muscle dystrophy (myotonic dystrophy type 2) that is caused by a single genetic mutation usually suffer from muscle weakness and wasting but a majority also suffer from chronic muscle pain in their extremities. In our study, we found that these patients are sensitive to pressure stimuli over muscles that are not usually perceived as painful. We also identified several muscle genes that might highlight a molecular link to muscle pain. These findings call for further research to learn how and whether the genetic impairments in muscle contribute to muscle pain.
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Affiliation(s)
- Rabih Moshourab
- Molecular Physiology of Somatic Sensation, Max Delbrück Center for Molecular Medicine, Berlin, Germany; Dept. of Anesthesiology, Charité Universitätsmedizin Berlin, Berlin, Germany
| | - Vinko Palada
- Muscle Research Unit, Experimental and Clinical Research Center, a joint cooperation of the Charité University Medicine Berlin and the Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Stefanie Grunwald
- Muscle Research Unit, Experimental and Clinical Research Center, a joint cooperation of the Charité University Medicine Berlin and the Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Ulrike Grieben
- Muscle Research Unit, Experimental and Clinical Research Center, a joint cooperation of the Charité University Medicine Berlin and the Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Gary R Lewin
- Molecular Physiology of Somatic Sensation, Max Delbrück Center for Molecular Medicine, Berlin, Germany.
| | - Simone Spuler
- Muscle Research Unit, Experimental and Clinical Research Center, a joint cooperation of the Charité University Medicine Berlin and the Max Delbrück Center for Molecular Medicine, Berlin, Germany.
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83
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Roles for RNA-binding proteins in development and disease. Brain Res 2016; 1647:1-8. [PMID: 26972534 DOI: 10.1016/j.brainres.2016.02.050] [Citation(s) in RCA: 106] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Revised: 02/24/2016] [Accepted: 02/25/2016] [Indexed: 12/13/2022]
Abstract
RNA-binding protein activities are highly regulated through protein levels, intracellular localization, and post-translation modifications. During development, mRNA processing of specific gene sets is regulated through manipulation of functional RNA-binding protein activities. The impact of altered RNA-binding protein activities also affects human diseases in which there are either a gain-of-function or loss-of-function causes pathogenesis. We will discuss RNA-binding proteins and their normal developmental RNA metabolism and contrast how their function is disrupted in disease. This article is part of a Special Issue entitled SI:RNA Metabolism in Disease.
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84
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Sultana N, Dienes B, Benedetti A, Tuluc P, Szentesi P, Sztretye M, Rainer J, Hess MW, Schwarzer C, Obermair GJ, Csernoch L, Flucher BE. Restricting calcium currents is required for correct fiber type specification in skeletal muscle. Development 2016; 143:1547-59. [PMID: 26965373 PMCID: PMC4909858 DOI: 10.1242/dev.129676] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Accepted: 02/29/2016] [Indexed: 11/20/2022]
Abstract
Skeletal muscle excitation-contraction (EC) coupling is independent of calcium influx. In fact, alternative splicing of the voltage-gated calcium channel CaV1.1 actively suppresses calcium currents in mature muscle. Whether this is necessary for normal development and function of muscle is not known. However, splicing defects that cause aberrant expression of the calcium-conducting developmental CaV1.1e splice variant correlate with muscle weakness in myotonic dystrophy. Here, we deleted CaV1.1 (Cacna1s) exon 29 in mice. These mice displayed normal overall motor performance, although grip force and voluntary running were reduced. Continued expression of the developmental CaV1.1e splice variant in adult mice caused increased calcium influx during EC coupling, altered calcium homeostasis, and spontaneous calcium sparklets in isolated muscle fibers. Contractile force was reduced and endurance enhanced. Key regulators of fiber type specification were dysregulated and the fiber type composition was shifted toward slower fibers. However, oxidative enzyme activity and mitochondrial content declined. These findings indicate that limiting calcium influx during skeletal muscle EC coupling is important for the secondary function of the calcium signal in the activity-dependent regulation of fiber type composition and to prevent muscle disease.
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Affiliation(s)
- Nasreen Sultana
- Department of Physiology and Medical Physics, Medical University Innsbruck, Innsbruck 6020, Austria
| | - Beatrix Dienes
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen 4032, Hungary
| | - Ariane Benedetti
- Department of Physiology and Medical Physics, Medical University Innsbruck, Innsbruck 6020, Austria
| | - Petronel Tuluc
- Department of Pharmacology, University of Innsbruck, Innsbruck 6020, Austria
| | - Peter Szentesi
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen 4032, Hungary
| | - Monika Sztretye
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen 4032, Hungary
| | - Johannes Rainer
- Division of Molecular Pathophysiology, Biocenter, Medical University Innsbruck, Innsbruck 6020, Austria
| | - Michael W Hess
- Division of Histology and Embryology, Medical University Innsbruck, Innsbruck 6020, Austria
| | - Christoph Schwarzer
- Department of Pharmacology, Medical University Innsbruck, Innsbruck 6020, Austria
| | - Gerald J Obermair
- Department of Physiology and Medical Physics, Medical University Innsbruck, Innsbruck 6020, Austria
| | - Laszlo Csernoch
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen 4032, Hungary
| | - Bernhard E Flucher
- Department of Physiology and Medical Physics, Medical University Innsbruck, Innsbruck 6020, Austria
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85
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Yadava RS, Foff EP, Yu Q, Gladman JT, Zheng TS, Mahadevan MS. TWEAK Regulates Muscle Functions in a Mouse Model of RNA Toxicity. PLoS One 2016; 11:e0150192. [PMID: 26901467 PMCID: PMC4762946 DOI: 10.1371/journal.pone.0150192] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Accepted: 02/09/2016] [Indexed: 12/31/2022] Open
Abstract
Myotonic dystrophy type 1 (DM1), the most common form of muscular dystrophy in adults, is caused by toxic RNAs produced from the mutant DM protein kinase (DMPK) gene. DM1 is characterized by progressive muscle wasting and weakness. Therapeutic strategies have mainly focused on targeting the toxic RNA. Previously, we found that fibroblast growth factor-inducible 14 (Fn14), the receptor for TWEAK, is induced in skeletal muscles and hearts of mouse models of RNA toxicity and that blocking TWEAK/Fn14 signaling improves muscle function and histology. Here, we studied the effect of Tweak deficiency in a RNA toxicity mouse model. The genetic deletion of Tweak in these mice significantly reduced muscle damage and improved muscle function. In contrast, administration of TWEAK in the RNA toxicity mice impaired functional outcomes and worsened muscle histopathology. These studies show that signaling via TWEAK is deleterious to muscle in RNA toxicity and support the demonstrated utility of anti-TWEAK therapeutics.
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Affiliation(s)
- Ramesh S. Yadava
- Department of Pathology, University of Virginia, Charlottesville, VA, United States of America
| | - Erin P. Foff
- Department of Neurology, University of Virginia, Charlottesville, VA, United States of America
| | - Qing Yu
- Department of Pathology, University of Virginia, Charlottesville, VA, United States of America
| | - Jordan T. Gladman
- Department of Pathology, University of Virginia, Charlottesville, VA, United States of America
| | - Timothy S. Zheng
- Department of Immunology, Biogen Idec, Cambridge, MA, United States of America
| | - Mani S. Mahadevan
- Department of Pathology, University of Virginia, Charlottesville, VA, United States of America
- * E-mail:
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86
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T Cell Receptor Mediated Calcium Entry Requires Alternatively Spliced Cav1.1 Channels. PLoS One 2016; 11:e0147379. [PMID: 26815481 PMCID: PMC4729531 DOI: 10.1371/journal.pone.0147379] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Accepted: 11/18/2015] [Indexed: 11/19/2022] Open
Abstract
The process of calcium entry in T cells is a multichannel and multi-step process. We have studied the requirement for L-type calcium channels (Cav1.1) α1S subunits during calcium entry after TCR stimulation. High expression levels of Cav1.1 channels were detected in activated T cells. Sequencing and cloning of Cav1.1 channel cDNA from T cells revealed that a single splice variant is expressed. This variant lacks exon 29, which encodes the linker region adjacent to the voltage sensor, but contains five new N-terminal exons that substitute for exons 1 and 2, which are found in the Cav1.1 muscle counterpart. Overexpression studies using cloned T cell Cav1.1 in 293HEK cells (that lack TCR) suggest that the gating of these channels was altered. Knockdown of Cav1.1 channels in T cells abrogated calcium entry after TCR stimulation, suggesting that Cav1.1 channels are controlled by TCR signaling.
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87
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Benedetti B, Tuluc P, Mastrolia V, Dlaska C, Flucher BE. Physiological and pharmacological modulation of the embryonic skeletal muscle calcium channel splice variant CaV1.1e. Biophys J 2016; 108:1072-80. [PMID: 25762319 PMCID: PMC4375451 DOI: 10.1016/j.bpj.2015.01.026] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Revised: 01/13/2015] [Accepted: 01/28/2015] [Indexed: 01/05/2023] Open
Abstract
CaV1.1e is the voltage-gated calcium channel splice variant of embryonic skeletal muscle. It differs from the adult CaV1.1a splice variant by the exclusion of exon 29 coding for 19 amino acids in the extracellular loop connecting transmembrane domains IVS3 and IVS4. Like the adult splice variant CaV1.1a, the embryonic CaV1.1e variant functions as voltage sensor in excitation-contraction coupling, but unlike CaV1.1a it also conducts sizable calcium currents. Consequently, physiological or pharmacological modulation of calcium currents may have a greater impact in CaV1.1e expressing muscle cells. Here, we analyzed the effects of L-type current modulators on whole-cell current properties in dysgenic (CaV1.1-null) myotubes reconstituted with either CaV1.1a or CaV1.1e. Furthermore, we examined the physiological current modulation by interactions with the ryanodine receptor using a chimeric CaV1.1e construct in which the cytoplasmic II-III loop, essential for skeletal muscle excitation-contraction coupling, has been replaced with the corresponding but nonfunctional loop from the Musca channel. Whereas the equivalent substitution in CaV1.1a had abolished the calcium currents, substitution of the II-III loop in CaV1.1e did not significantly reduce current amplitudes. This indicates that CaV1.1e is not subject to retrograde coupling with the ryanodine receptor and that the retrograde coupling mechanism in CaV1.1a operates by counteracting the limiting effects of exon 29 inclusion on the current amplitude. Pharmacologically, CaV1.1e behaves like other L-type calcium channels. Its currents are substantially increased by the calcium channel agonist Bay K 8644 and inhibited by the calcium channel blocker nifedipine in a dose-dependent manner. With an IC50 of 0.37 μM for current inhibition by nifedipine, CaV1.1e is a potential drug target for the treatment of myotonic dystrophy. It might block the excessive calcium influx resulting from the aberrant expression of the embryonic splice variant CaV1.1e in the skeletal muscles of myotonic dystrophy patients.
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MESH Headings
- 3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester/pharmacology
- Animals
- Calcium/metabolism
- Calcium Channel Blockers/pharmacology
- Calcium Channels, L-Type/drug effects
- Calcium Channels, L-Type/genetics
- Calcium Channels, L-Type/metabolism
- Cell Line, Tumor
- Excitation Contraction Coupling
- Muscle Fibers, Skeletal/drug effects
- Muscle Fibers, Skeletal/metabolism
- Muscle Fibers, Skeletal/physiology
- Nifedipine/pharmacology
- Protein Isoforms/drug effects
- Protein Isoforms/genetics
- Protein Isoforms/metabolism
- Rats
- Ryanodine Receptor Calcium Release Channel/metabolism
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Affiliation(s)
- Bruno Benedetti
- Department of Physiology and Medical Physics, Medical University Innsbruck, Innsbruck, Austria
| | - Petronel Tuluc
- Department of Physiology and Medical Physics, Medical University Innsbruck, Innsbruck, Austria; Pharmacology and Toxicology, Institute of Pharmacy, University of Innsbruck, Innsbruck, Austria
| | - Vincenzo Mastrolia
- Department of Physiology and Medical Physics, Medical University Innsbruck, Innsbruck, Austria
| | - Clemens Dlaska
- Department of Physiology and Medical Physics, Medical University Innsbruck, Innsbruck, Austria
| | - Bernhard E Flucher
- Department of Physiology and Medical Physics, Medical University Innsbruck, Innsbruck, Austria.
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88
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Electromechanical delay components during skeletal muscle contraction and relaxation in patients with myotonic dystrophy type 1. Neuromuscul Disord 2016; 26:60-72. [DOI: 10.1016/j.nmd.2015.09.013] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Revised: 09/15/2015] [Accepted: 09/19/2015] [Indexed: 12/20/2022]
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89
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Nakamori M, Taylor K, Mochizuki H, Sobczak K, Takahashi MP. Oral administration of erythromycin decreases RNA toxicity in myotonic dystrophy. Ann Clin Transl Neurol 2015; 3:42-54. [PMID: 26783549 PMCID: PMC4704483 DOI: 10.1002/acn3.271] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2015] [Accepted: 11/04/2015] [Indexed: 11/08/2022] Open
Abstract
OBJECTIVE Myotonic dystrophy type 1 (DM1) is caused by the expansion of a CTG repeat in the 3' untranslated region of DMPK. The transcripts containing an expanded CUG repeat (CUG (exp)) result in a toxic gain-of-function by forming ribonuclear foci that sequester the alternative splicing factor muscleblind-like 1 (MBNL1). Although several small molecules reportedly ameliorate RNA toxicity, none are ready for clinical use because of the lack of safety data. Here, we undertook a drug-repositioning screen to identify a safe and effective small molecule for upcoming clinical trials of DM1. METHODS We examined the potency of small molecules in inhibiting the interaction between CUG (exp) and MBNL1 by in vitro sequestration and fluorescent titration assays. We studied the effect of lead compounds in DM1 model cells by evaluating foci reduction and splicing rescue. We also tested their effects on missplicing and myotonia in DM1 model mice. RESULTS Of the 20 FDA-approved small molecules tested, erythromycin showed the highest affinity to CUG (exp) and a capacity to inhibit its binding to MBNL1. Erythromycin decreased foci formation and rescued missplicing in DM1 cell models. Both systemic and oral administration of erythromycin in the DM1 model mice showed splicing reversal and improvement of myotonia with no toxicity. Long-term oral administration of erythromycin at the dose used in humans also improved the splicing abnormality in the DM1 model mice. INTERPRETATION Oral erythromycin treatment, which has been widely used in humans with excellent tolerability, may be a promising therapy for DM1.
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Affiliation(s)
- Masayuki Nakamori
- Department of Neurology Osaka University Graduate School of Medicine Osaka Japan
| | - Katarzyna Taylor
- Department of Gene Expression Institute of Molecular Biology and Biotechnology Adam Mickiewicz University Posnan Poland
| | - Hideki Mochizuki
- Department of Neurology Osaka University Graduate School of Medicine Osaka Japan
| | - Krzysztof Sobczak
- Department of Gene Expression Institute of Molecular Biology and Biotechnology Adam Mickiewicz University Posnan Poland
| | - Masanori P Takahashi
- Department of Neurology Osaka University Graduate School of Medicine Osaka Japan
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90
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Tang Y, Wang H, Wei B, Guo Y, Gu L, Yang Z, Zhang Q, Wu Y, Yuan Q, Zhao G, Ji G. CUG-BP1 regulates RyR1 ASI alternative splicing in skeletal muscle atrophy. Sci Rep 2015; 5:16083. [PMID: 26531141 PMCID: PMC4632035 DOI: 10.1038/srep16083] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Accepted: 09/30/2015] [Indexed: 02/06/2023] Open
Abstract
RNA binding protein is identified as an important mediator of aberrant alternative splicing in muscle atrophy. The altered splicing of calcium channels, such as ryanodine receptors (RyRs), plays an important role in impaired excitation-contraction (E-C) coupling in muscle atrophy; however, the regulatory mechanisms of ryanodine receptor 1 (RyR1) alternative splicing leading to skeletal muscle atrophy remains to be investigated. In this study we demonstrated that CUG binding protein 1 (CUG-BP1) was up-regulated and the alternative splicing of RyR1 ASI (exon70) was aberrant during the process of neurogenic muscle atrophy both in human patients and mouse models. The gain and loss of function experiments in vivo demonstrated that altered splicing pattern of RyR1 ASI was directly mediated by an up-regulated CUG-BP1 function. Furthermore, we found that CUG-BP1 affected the calcium release activity in single myofibers and the extent of atrophy was significantly reduced upon gene silencing of CUG-BP1 in atrophic muscle. These findings improve our understanding of calcium signaling related biological function of CUG-BP1 in muscle atrophy. Thus, we provide an intriguing perspective of involvement of mis-regulated RyR1 splicing in muscular disease.
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Affiliation(s)
- Yinglong Tang
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China.,University of the Chinese Academy of Sciences, Beijing 100049, China
| | - Huiwen Wang
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China
| | - Bin Wei
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan 48201
| | - Yuting Guo
- University of the Chinese Academy of Sciences, Beijing 100049, China
| | - Lei Gu
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China.,University of the Chinese Academy of Sciences, Beijing 100049, China
| | - Zhiguang Yang
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China.,University of the Chinese Academy of Sciences, Beijing 100049, China
| | - Qing Zhang
- Department of Anesthesiology, Beijing Tiantan Hospital, Capital Medical University, Beijing 100050, China
| | - Yanyun Wu
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China
| | - Qi Yuan
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China
| | - Gang Zhao
- Department of Neurology, Xijing Hospital, Forth Military Medical University, Xi'an, Shaanxi 710032, China
| | - Guangju Ji
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China
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91
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Chakraborty M, Selma-Soriano E, Magny E, Couso JP, Pérez-Alonso M, Charlet-Berguerand N, Artero R, Llamusi B. Pentamidine rescues contractility and rhythmicity in a Drosophila model of myotonic dystrophy heart dysfunction. Dis Model Mech 2015; 8:1569-78. [PMID: 26515653 PMCID: PMC4728315 DOI: 10.1242/dmm.021428] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Accepted: 10/19/2015] [Indexed: 02/01/2023] Open
Abstract
Up to 80% of individuals with myotonic dystrophy type 1 (DM1) will develop cardiac abnormalities at some point during the progression of their disease, the most common of which is heart blockage of varying degrees. Such blockage is characterized by conduction defects and supraventricular and ventricular tachycardia, and carries a high risk of sudden cardiac death. Despite its importance, very few animal model studies have focused on the heart dysfunction in DM1. Here, we describe the characterization of the heart phenotype in a Drosophila model expressing pure expanded CUG repeats under the control of the cardiomyocyte-specific driver GMH5-Gal4. Morphologically, expression of 250 CUG repeats caused abnormalities in the parallel alignment of the spiral myofibrils in dissected fly hearts, as revealed by phalloidin staining. Moreover, combined immunofluorescence and in situ hybridization of Muscleblind and CUG repeats, respectively, confirmed detectable ribonuclear foci and Muscleblind sequestration, characteristic features of DM1, exclusively in flies expressing the expanded CTG repeats. Similarly to what has been reported in humans with DM1, heart-specific expression of toxic RNA resulted in reduced survival, increased arrhythmia, altered diastolic and systolic function, reduced heart tube diameters and reduced contractility in the model flies. As a proof of concept that the fly heart model can be used for in vivo testing of promising therapeutic compounds, we fed flies with pentamidine, a compound previously described to improve DM1 phenotypes. Pentamidine not only released Muscleblind from the CUG RNA repeats and reduced ribonuclear formation in the Drosophila heart, but also rescued heart arrhythmicity and contractility, and improved fly survival in animals expressing 250 CUG repeats.
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Affiliation(s)
- Mouli Chakraborty
- Translational Genomics Group, Incliva Health Research Institute, Avda. Menendez Pelayo 4 acc 46010, Valencia, Spain Department of Genetics and Estructura de Recerca Interdisciplinar en Biotecnologia i Biomedicina (ERI BIOTECMED), Universitat de València, Dr Moliner 50, Burjasot 46100, Spain
| | - Estela Selma-Soriano
- Department of Genetics and Estructura de Recerca Interdisciplinar en Biotecnologia i Biomedicina (ERI BIOTECMED), Universitat de València, Dr Moliner 50, Burjasot 46100, Spain
| | - Emile Magny
- School of Life Sciences, University of Sussex, Falmer, Brighton, East Sussex, BN1 9QG, UK
| | - Juan Pablo Couso
- School of Life Sciences, University of Sussex, Falmer, Brighton, East Sussex, BN1 9QG, UK
| | - Manuel Pérez-Alonso
- Translational Genomics Group, Incliva Health Research Institute, Avda. Menendez Pelayo 4 acc 46010, Valencia, Spain Department of Genetics and Estructura de Recerca Interdisciplinar en Biotecnologia i Biomedicina (ERI BIOTECMED), Universitat de València, Dr Moliner 50, Burjasot 46100, Spain
| | - Nicolas Charlet-Berguerand
- Translational Medicine and Neurogenetics, Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), 1 Rue Laurent Fries, 67400 Illkirch-Graffenstaden, France
| | - Ruben Artero
- Translational Genomics Group, Incliva Health Research Institute, Avda. Menendez Pelayo 4 acc 46010, Valencia, Spain Department of Genetics and Estructura de Recerca Interdisciplinar en Biotecnologia i Biomedicina (ERI BIOTECMED), Universitat de València, Dr Moliner 50, Burjasot 46100, Spain
| | - Beatriz Llamusi
- Translational Genomics Group, Incliva Health Research Institute, Avda. Menendez Pelayo 4 acc 46010, Valencia, Spain Department of Genetics and Estructura de Recerca Interdisciplinar en Biotecnologia i Biomedicina (ERI BIOTECMED), Universitat de València, Dr Moliner 50, Burjasot 46100, Spain
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92
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Zamponi GW, Striessnig J, Koschak A, Dolphin AC. The Physiology, Pathology, and Pharmacology of Voltage-Gated Calcium Channels and Their Future Therapeutic Potential. Pharmacol Rev 2015; 67:821-70. [PMID: 26362469 PMCID: PMC4630564 DOI: 10.1124/pr.114.009654] [Citation(s) in RCA: 704] [Impact Index Per Article: 78.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Voltage-gated calcium channels are required for many key functions in the body. In this review, the different subtypes of voltage-gated calcium channels are described and their physiologic roles and pharmacology are outlined. We describe the current uses of drugs interacting with the different calcium channel subtypes and subunits, as well as specific areas in which there is strong potential for future drug development. Current therapeutic agents include drugs targeting L-type Ca(V)1.2 calcium channels, particularly 1,4-dihydropyridines, which are widely used in the treatment of hypertension. T-type (Ca(V)3) channels are a target of ethosuximide, widely used in absence epilepsy. The auxiliary subunit α2δ-1 is the therapeutic target of the gabapentinoid drugs, which are of value in certain epilepsies and chronic neuropathic pain. The limited use of intrathecal ziconotide, a peptide blocker of N-type (Ca(V)2.2) calcium channels, as a treatment of intractable pain, gives an indication that these channels represent excellent drug targets for various pain conditions. We describe how selectivity for different subtypes of calcium channels (e.g., Ca(V)1.2 and Ca(V)1.3 L-type channels) may be achieved in the future by exploiting differences between channel isoforms in terms of sequence and biophysical properties, variation in splicing in different target tissues, and differences in the properties of the target tissues themselves in terms of membrane potential or firing frequency. Thus, use-dependent blockers of the different isoforms could selectively block calcium channels in particular pathologies, such as nociceptive neurons in pain states or in epileptic brain circuits. Of important future potential are selective Ca(V)1.3 blockers for neuropsychiatric diseases, neuroprotection in Parkinson's disease, and resistant hypertension. In addition, selective or nonselective T-type channel blockers are considered potential therapeutic targets in epilepsy, pain, obesity, sleep, and anxiety. Use-dependent N-type calcium channel blockers are likely to be of therapeutic use in chronic pain conditions. Thus, more selective calcium channel blockers hold promise for therapeutic intervention.
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Affiliation(s)
- Gerald W Zamponi
- Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada (G.W.Z.); Department of Pharmacology and Toxicology, Institute of Pharmacy, Center for Molecular Biosciences, University of Innsbruck, Innsbruck, Austria (J.S., A.K.); and Department of Neuroscience, Physiology, and Pharmacology, Division of Biosciences, University College London, London, United Kingdom (A.C.D.)
| | - Joerg Striessnig
- Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada (G.W.Z.); Department of Pharmacology and Toxicology, Institute of Pharmacy, Center for Molecular Biosciences, University of Innsbruck, Innsbruck, Austria (J.S., A.K.); and Department of Neuroscience, Physiology, and Pharmacology, Division of Biosciences, University College London, London, United Kingdom (A.C.D.)
| | - Alexandra Koschak
- Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada (G.W.Z.); Department of Pharmacology and Toxicology, Institute of Pharmacy, Center for Molecular Biosciences, University of Innsbruck, Innsbruck, Austria (J.S., A.K.); and Department of Neuroscience, Physiology, and Pharmacology, Division of Biosciences, University College London, London, United Kingdom (A.C.D.)
| | - Annette C Dolphin
- Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada (G.W.Z.); Department of Pharmacology and Toxicology, Institute of Pharmacy, Center for Molecular Biosciences, University of Innsbruck, Innsbruck, Austria (J.S., A.K.); and Department of Neuroscience, Physiology, and Pharmacology, Division of Biosciences, University College London, London, United Kingdom (A.C.D.)
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93
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Meola G, Cardani R. Myotonic Dystrophy Type 2: An Update on Clinical Aspects, Genetic and Pathomolecular Mechanism. J Neuromuscul Dis 2015; 2:S59-S71. [PMID: 27858759 PMCID: PMC5240594 DOI: 10.3233/jnd-150088] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Myotonic dystrophy (DM) is the most common adult muscular dystrophy, characterized by autosomal dominant progressive myopathy, myotonia and multiorgan involvement. To date two distinct forms caused by similar mutations have been identified. Myotonic dystrophy type 1 (DM1, Steinert's disease) is caused by a (CTG)n expansion in DMPK, while myotonic dystrophy type 2 (DM2) is caused by a (CCTG)n expansion in CNBP. Despite clinical and genetic similarities, DM1 and DM2 are distinct disorders. The pathogenesis of DM is explained by a common RNA gain-of-function mechanism in which the CUG and CCUG repeats alter cellular function, including alternative splicing of various genes. However additional pathogenic mechanism like changes in gene expression, modifier genes, protein translation and micro-RNA metabolism may also contribute to disease pathology and to clarify the phenotypic differences between these two types of myotonic dystrophies.This review is an update on the latest findings specific to DM2, including explanations for the differences in clinical manifestations and pathophysiology between the two forms of myotonic dystrophies.
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Affiliation(s)
- Giovanni Meola
- Department of Biomedical Sciences for Health, IRCCS Policlinico San Donato, University of Milan, San Donato Milanese, Milan, Italy
- Laboratory of Muscle Histopathology and Molecular Biology, IRCCS Policlinico San Donato, San Donato Milanese, Milan, Italy
| | - Rosanna Cardani
- Laboratory of Muscle Histopathology and Molecular Biology, IRCCS Policlinico San Donato, San Donato Milanese, Milan, Italy
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94
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Frese KS, Meder B, Keller A, Just S, Haas J, Vogel B, Fischer S, Backes C, Matzas M, Köhler D, Benes V, Katus HA, Rottbauer W. RNA splicing regulated by RBFOX1 is essential for cardiac function in zebrafish. J Cell Sci 2015; 128:3030-40. [PMID: 26116573 PMCID: PMC4541041 DOI: 10.1242/jcs.166850] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2014] [Accepted: 05/10/2015] [Indexed: 12/21/2022] Open
Abstract
Alternative splicing is one of the major mechanisms through which the proteomic and functional diversity of eukaryotes is achieved. However, the complex nature of the splicing machinery, its associated splicing regulators and the functional implications of alternatively spliced transcripts are only poorly understood. Here, we investigated the functional role of the splicing regulator rbfox1 in vivo using the zebrafish as a model system. We found that loss of rbfox1 led to progressive cardiac contractile dysfunction and heart failure. By using deep-transcriptome sequencing and quantitative real-time PCR, we show that depletion of rbfox1 in zebrafish results in an altered isoform expression of several crucial target genes, such as actn3a and hug. This study underlines that tightly regulated splicing is necessary for unconstrained cardiac function and renders the splicing regulator rbfox1 an interesting target for investigation in human heart failure and cardiomyopathy. Summary: The zebrafish splicing regulator rbfox1 is necessary for tightly regulated splicing and unconstrained cardiac function, making it an interesting candidate for targeting during human cardiomyopathy.
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Affiliation(s)
- Karen S Frese
- Department of Medicine III, University of Heidelberg, D-69120 Heidelberg, Germany German Centre for Cardiovascular Research (DZHK), partner site Heidelberg/Mannheim, D-69120 Heidelberg, Germany
| | - Benjamin Meder
- Department of Medicine III, University of Heidelberg, D-69120 Heidelberg, Germany German Centre for Cardiovascular Research (DZHK), partner site Heidelberg/Mannheim, D-69120 Heidelberg, Germany
| | - Andreas Keller
- Chair for Clinical Bioinformatics, Saarland University, D-66123 Saarbrücken, Germany Department of Human Genetics, Saarland University, D-66123 Saarbrücken, Germany
| | - Steffen Just
- Department of Medicine II, University of Ulm, D-89081 Ulm, Germany
| | - Jan Haas
- Department of Medicine III, University of Heidelberg, D-69120 Heidelberg, Germany German Centre for Cardiovascular Research (DZHK), partner site Heidelberg/Mannheim, D-69120 Heidelberg, Germany
| | - Britta Vogel
- Department of Medicine III, University of Heidelberg, D-69120 Heidelberg, Germany German Centre for Cardiovascular Research (DZHK), partner site Heidelberg/Mannheim, D-69120 Heidelberg, Germany
| | - Simon Fischer
- Department of Medicine III, University of Heidelberg, D-69120 Heidelberg, Germany German Centre for Cardiovascular Research (DZHK), partner site Heidelberg/Mannheim, D-69120 Heidelberg, Germany
| | - Christina Backes
- Department of Human Genetics, Saarland University, D-66123 Saarbrücken, Germany
| | - Mark Matzas
- Comprehensive Biomarker Center, D-69120 Heidelberg, Germany
| | - Doreen Köhler
- Department of Medicine III, University of Heidelberg, D-69120 Heidelberg, Germany
| | - Vladimir Benes
- EMBL, European Molecular Biology Laboratory, Genomics Core Facility, D-69117 Heidelberg, Germany
| | - Hugo A Katus
- Department of Medicine III, University of Heidelberg, D-69120 Heidelberg, Germany German Centre for Cardiovascular Research (DZHK), partner site Heidelberg/Mannheim, D-69120 Heidelberg, Germany
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95
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Rau F, Lainé J, Ramanoudjame L, Ferry A, Arandel L, Delalande O, Jollet A, Dingli F, Lee KY, Peccate C, Lorain S, Kabashi E, Athanasopoulos T, Koo T, Loew D, Swanson MS, Le Rumeur E, Dickson G, Allamand V, Marie J, Furling D. Abnormal splicing switch of DMD's penultimate exon compromises muscle fibre maintenance in myotonic dystrophy. Nat Commun 2015; 6:7205. [PMID: 26018658 PMCID: PMC4458869 DOI: 10.1038/ncomms8205] [Citation(s) in RCA: 69] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Accepted: 04/16/2015] [Indexed: 02/06/2023] Open
Abstract
Myotonic Dystrophy type 1 (DM1) is a dominant neuromuscular disease caused by nuclear-retained RNAs containing expanded CUG repeats. These toxic RNAs alter the activities of RNA splicing factors resulting in alternative splicing misregulation and muscular dysfunction. Here we show that the abnormal splicing of DMD exon 78 found in dystrophic muscles of DM1 patients is due to the functional loss of MBNL1 and leads to the re-expression of an embryonic dystrophin in place of the adult isoform. Forced expression of embryonic dystrophin in zebrafish using an exon-skipping approach severely impairs the mobility and muscle architecture. Moreover, reproducing Dmd exon 78 missplicing switch in mice induces muscle fibre remodelling and ultrastructural abnormalities including ringed fibres, sarcoplasmic masses or Z-band disorganization, which are characteristic features of dystrophic DM1 skeletal muscles. Thus, we propose that splicing misregulation of DMD exon 78 compromises muscle fibre maintenance and contributes to the progressive dystrophic process in DM1.
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Affiliation(s)
- Frédérique Rau
- Sorbonne Universités, UPMC Univ Paris 06, INSERM UMRS974, CNRS FRE3617, Center for Research in Myology, Institut de Myologie, GH Pitié-Salpêtrière, F-75013 Paris, France
| | - Jeanne Lainé
- Sorbonne Universités, UPMC Univ Paris 06, INSERM UMRS974, CNRS FRE3617, Center for Research in Myology, Institut de Myologie, GH Pitié-Salpêtrière, F-75013 Paris, France.,Sorbonne Universités, UPMC Paris 06, Département de Physiologie, Site Pitié-Salpêtrière, F-75013 Paris, France
| | - Laetitita Ramanoudjame
- Sorbonne Universités, UPMC Univ Paris 06, INSERM UMRS974, CNRS FRE3617, Center for Research in Myology, Institut de Myologie, GH Pitié-Salpêtrière, F-75013 Paris, France
| | - Arnaud Ferry
- Sorbonne Universités, UPMC Univ Paris 06, INSERM UMRS974, CNRS FRE3617, Center for Research in Myology, Institut de Myologie, GH Pitié-Salpêtrière, F-75013 Paris, France
| | - Ludovic Arandel
- Sorbonne Universités, UPMC Univ Paris 06, INSERM UMRS974, CNRS FRE3617, Center for Research in Myology, Institut de Myologie, GH Pitié-Salpêtrière, F-75013 Paris, France
| | - Olivier Delalande
- Université de Rennes 1, Institut de Génétique et Développement de Rennes, F-35043 Rennes, France
| | - Arnaud Jollet
- Sorbonne Universités, UPMC Univ Paris 06, INSERM UMRS974, CNRS FRE3617, Center for Research in Myology, Institut de Myologie, GH Pitié-Salpêtrière, F-75013 Paris, France
| | - Florent Dingli
- Institut Curie, Centre de Recherche, Laboratoire de Spectrométrie de Masse Protéomique, F-75005 Paris, France
| | - Kuang-Yung Lee
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics and the Genetics Institute, University of Florida, College of Medicine, Gainesville, Florida 32610, USA.,Department of Neurology, Chang Gung Memorial Hospital, Keelung 204, Taiwan
| | - Cécile Peccate
- Sorbonne Universités, UPMC Univ Paris 06, INSERM UMRS974, CNRS FRE3617, Center for Research in Myology, Institut de Myologie, GH Pitié-Salpêtrière, F-75013 Paris, France
| | - Stéphanie Lorain
- Sorbonne Universités, UPMC Univ Paris 06, INSERM UMRS974, CNRS FRE3617, Center for Research in Myology, Institut de Myologie, GH Pitié-Salpêtrière, F-75013 Paris, France
| | - Edor Kabashi
- Sorbonne Université, UPMC Univ Paris 06, UM 75, INSERM U1127, CNRS UMR7225, ICM, Paris, F-75013 Paris, France
| | - Takis Athanasopoulos
- School of Biological Sciences, Royal Holloway-University of London, Egham, Surrey, TW20 0EX, UK
| | - Taeyoung Koo
- School of Biological Sciences, Royal Holloway-University of London, Egham, Surrey, TW20 0EX, UK
| | - Damarys Loew
- Institut Curie, Centre de Recherche, Laboratoire de Spectrométrie de Masse Protéomique, F-75005 Paris, France
| | - Maurice S Swanson
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics and the Genetics Institute, University of Florida, College of Medicine, Gainesville, Florida 32610, USA
| | - Elisabeth Le Rumeur
- Université de Rennes 1, Institut de Génétique et Développement de Rennes, F-35043 Rennes, France
| | - George Dickson
- School of Biological Sciences, Royal Holloway-University of London, Egham, Surrey, TW20 0EX, UK
| | - Valérie Allamand
- Sorbonne Universités, UPMC Univ Paris 06, INSERM UMRS974, CNRS FRE3617, Center for Research in Myology, Institut de Myologie, GH Pitié-Salpêtrière, F-75013 Paris, France
| | - Joëlle Marie
- Sorbonne Universités, UPMC Univ Paris 06, INSERM UMRS974, CNRS FRE3617, Center for Research in Myology, Institut de Myologie, GH Pitié-Salpêtrière, F-75013 Paris, France
| | - Denis Furling
- Sorbonne Universités, UPMC Univ Paris 06, INSERM UMRS974, CNRS FRE3617, Center for Research in Myology, Institut de Myologie, GH Pitié-Salpêtrière, F-75013 Paris, France
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Dixon DM, Choi J, El-Ghazali A, Park SY, Roos KP, Jordan MC, Fishbein MC, Comai L, Reddy S. Loss of muscleblind-like 1 results in cardiac pathology and persistence of embryonic splice isoforms. Sci Rep 2015; 5:9042. [PMID: 25761764 PMCID: PMC4356957 DOI: 10.1038/srep09042] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Accepted: 02/02/2015] [Indexed: 01/05/2023] Open
Abstract
Cardiac dysfunction is a prominent cause of mortality in myotonic dystrophy I (DM1), a disease where expanded CUG repeats bind and disable the muscleblind-like family of splice regulators. Deletion of muscleblind-like 1 (Mbnl1ΔE2/ΔE2) in 129 sv mice results in QRS, QTc widening, bundle block and STc narrowing at 2–4 months of age. With time, cardiac function deteriorates further and at 6 months, decreased R wave amplitudes, sinus node dysfunction, cardiac hypertrophy, interstitial fibrosis, multi-focal myocardial fiber death and calcification manifest. Sudden death, where no end point illness is overt, is observed at a median age of 6.5 and 4.8 months in ~67% and ~86% of male and female Mbnl1ΔE2/ΔE2 mice, respectively. Mbnl1 depletion results in the persistence of embryonic splice isoforms in a network of cardiac RNAs, some of which have been previously implicated in DM1, regulating sodium and calcium currents, Scn5a, Junctin, Junctate, Atp2a1, Atp11a, Cacna1s, Ryr2, intra and inter cellular transport, Clta, Stx2, Tjp1, cell survival, Capn3, Sirt2, Csda, sarcomere and cytoskeleton organization and function, Trim55, Mapt, Pdlim3, Pdlim5, Sorbs1, Sorbs2, Fhod1, Spag9 and structural components of the sarcomere, Myom1, Tnnt2, Zasp. Thus this study supports a key role for Mbnl1 loss in the initiation of DM1 cardiac disease.
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Affiliation(s)
- Donald M Dixon
- Department of Biochemistry and Molecular Biology, University of Southern California, Los Angeles, CA 90033, USA
| | - Jongkyu Choi
- Department of Biochemistry and Molecular Biology, University of Southern California, Los Angeles, CA 90033, USA
| | - Ayea El-Ghazali
- 1] Department of Biochemistry and Molecular Biology, University of Southern California, Los Angeles, CA 90033, USA [2] Department of Microbiology and Immunology, University of Southern California, Los Angeles, CA 90033, USA
| | - Sun Young Park
- Department of Biochemistry and Molecular Biology, University of Southern California, Los Angeles, CA 90033, USA
| | - Kenneth P Roos
- Department of Physiology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
| | - Maria C Jordan
- Department of Physiology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
| | - Michael C Fishbein
- Department of Pathology and Laboratory Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
| | - Lucio Comai
- Department of Microbiology and Immunology, University of Southern California, Los Angeles, CA 90033, USA
| | - Sita Reddy
- Department of Biochemistry and Molecular Biology, University of Southern California, Los Angeles, CA 90033, USA
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97
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Ca(2+) permeation and/or binding to CaV1.1 fine-tunes skeletal muscle Ca(2+) signaling to sustain muscle function. Skelet Muscle 2015; 5:4. [PMID: 25717360 PMCID: PMC4340672 DOI: 10.1186/s13395-014-0027-1] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2014] [Accepted: 12/11/2014] [Indexed: 11/13/2022] Open
Abstract
Background Ca2+ influx through CaV1.1 is not required for skeletal muscle excitation-contraction coupling, but whether Ca2+ permeation through CaV1.1 during sustained muscle activity plays a functional role in mammalian skeletal muscle has not been assessed. Methods We generated a mouse with a Ca2+ binding and/or permeation defect in the voltage-dependent Ca2+ channel, CaV1.1, and used Ca2+ imaging, western blotting, immunohistochemistry, proximity ligation assays, SUnSET analysis of protein synthesis, and Ca2+ imaging techniques to define pathways modulated by Ca2+ binding and/or permeation of CaV1.1. We also assessed fiber type distributions, cross-sectional area, and force frequency and fatigue in isolated muscles. Results Using mice with a pore mutation in CaV1.1 required for Ca2+ binding and/or permeation (E1014K, EK), we demonstrate that CaV1.1 opening is coupled to CaMKII activation and refilling of sarcoplasmic reticulum Ca2+ stores during sustained activity. Decreases in these Ca2+-dependent enzyme activities alter downstream signaling pathways (Ras/Erk/mTORC1) that lead to decreased muscle protein synthesis. The physiological consequences of the permeation and/or Ca2+ binding defect in CaV1.1 are increased fatigue, decreased fiber size, and increased Type IIb fibers. Conclusions While not essential for excitation-contraction coupling, Ca2+ binding and/or permeation via the CaV1.1 pore plays an important modulatory role in muscle performance. Electronic supplementary material The online version of this article (doi:10.1186/s13395-014-0027-1) contains supplementary material, which is available to authorized users.
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98
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Beqollari D, Romberg CF, Meza U, Papadopoulos S, Bannister RA. Differential effects of RGK proteins on L-type channel function in adult mouse skeletal muscle. Biophys J 2014; 106:1950-7. [PMID: 24806927 DOI: 10.1016/j.bpj.2014.03.033] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2013] [Revised: 02/24/2014] [Accepted: 03/25/2014] [Indexed: 11/19/2022] Open
Abstract
Work in heterologous systems has revealed that members of the Rad, Rem, Rem2, Gem/Kir (RGK) family of small GTP-binding proteins profoundly inhibit L-type Ca(2+) channels via three mechanisms: 1), reduction of membrane expression; 2), immobilization of the voltage-sensors; and 3), reduction of Po without impaired voltage-sensor movement. However, the question of which mode is the critical one for inhibition of L-type channels in their native environments persists. To address this conundrum in skeletal muscle, we overexpressed Rad and Rem in flexor digitorum brevis (FDB) fibers via in vivo electroporation and examined the abilities of these two RGK isoforms to modulate the L-type Ca(2+) channel (CaV1.1). We found that Rad and Rem both potently inhibit L-type current in FDB fibers. However, intramembrane charge movement was only reduced in fibers transfected with Rad; charge movement for Rem-expressing fibers was virtually identical to charge movement observed in naïve fibers. This result indicated that Rem supports inhibition solely through a mechanism that allows for translocation of CaV1.1's voltage-sensors, whereas Rad utilizes at least one mode that limits voltage-sensor movement. Because Rad and Rem differ significantly only in their amino-termini, we constructed Rad-Rem chimeras to probe the structural basis for the distinct specificities of Rad- and Rem-mediated inhibition. Using this approach, a chimera composed of the amino-terminus of Rem and the core/carboxyl-terminus of Rad inhibited L-type current without reducing charge movement. Conversely, a chimera having the amino-terminus of Rad fused to the core/carboxyl-terminus of Rem inhibited L-type current with a concurrent reduction in charge movement. Thus, we have identified the amino-termini of Rad and Rem as the structural elements dictating the specific modes of inhibition of CaV1.1.
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Affiliation(s)
- D Beqollari
- Department of Medicine-Cardiology Division, University of Colorado Denver-Anschutz Medical Campus, Aurora, Colorado
| | - C F Romberg
- Department of Medicine-Cardiology Division, University of Colorado Denver-Anschutz Medical Campus, Aurora, Colorado
| | - U Meza
- Department of Medicine-Cardiology Division, University of Colorado Denver-Anschutz Medical Campus, Aurora, Colorado; Departamento de Fisiología y Biofísica, Facultad de Medicina, Universidad Autónoma de San Luis Potosí, San Luis Potosí, México
| | - S Papadopoulos
- Institute of Vegetative Physiology, University Hospital of Cologne, Cologne, Germany
| | - R A Bannister
- Department of Medicine-Cardiology Division, University of Colorado Denver-Anschutz Medical Campus, Aurora, Colorado.
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99
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Ohsawa N, Koebis M, Mitsuhashi H, Nishino I, Ishiura S. ABLIM1 splicing is abnormal in skeletal muscle of patients with DM1 and regulated by MBNL, CELF and PTBP1. Genes Cells 2014; 20:121-34. [PMID: 25403273 DOI: 10.1111/gtc.12201] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2014] [Accepted: 10/14/2014] [Indexed: 12/16/2022]
Abstract
Myotonic dystrophy type 1 (DM1) is an RNA-mediated disorder characterized by muscle weakness, cardiac defects and multiple symptoms and is caused by expanded CTG repeats within the 3' untranslated region of the DMPK gene. In this study, we found abnormal splicing of actin-binding LIM protein 1 (ABLIM1) in skeletal muscles of patients with DM1 and a DM1 mouse model (HSA(LR) ). An exon 11 inclusion isoform is expressed in skeletal muscle and heart of non-DM1 individuals, but not in skeletal muscle of patients with DM1 or other adult human tissues. Moreover, we determined that ABLIM1 splicing is regulated by several splice factors, including MBNL family proteins, CELF1, 2 and 6, and PTBP1, using a cellular splicing assay. MBNL proteins promoted the inclusion of ABLIM1 exon 11, but other proteins and expanded CUG repeats repressed exon 11 of ABLIM1. This result is consistent with the hypothesis that MBNL proteins are trapped by expanded CUG repeats and inactivated in DM1 and that CELF1 is activated in DM1. However, activation of PTBP1 has not been reported in DM1. Our results suggest that the exon 11 inclusion isoform of ABLIM1 may have a muscle-specific function, and its abnormal splicing could be related to muscle symptoms of DM1.
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Affiliation(s)
- Natsumi Ohsawa
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1, Komaba, Meguro-ku, Tokyo, 153-8902, Japan
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Abstract
Muscular dystrophies are a group of diseases characterised by the primary wasting of skeletal muscle, which compromises patient mobility and in the most severe cases originate a complete paralysis and premature death. Existing evidence implicates calcium dysregulation as an underlying crucial event in the pathophysiology of several muscular dystrophies, such as dystrophinopathies, calpainopathies or myotonic dystrophy among others. Duchenne muscular dystrophy is the most frequent myopathy in childhood, and calpainopathy or LGMD2A is the most common form of limb-girdle muscular dystrophy, whereas myotonic dystrophy is the most frequent inherited muscle disease worldwide. In this review, we summarise recent advances in our understanding of calcium ion cycling through the sarcolemma, the sarcoplasmic reticulum and mitochondria, and its involvement in the pathogenesis of these dystrophies. We also discuss some of the clinical implications of recent findings regarding Ca2+ handling as well as novel approaches to treat muscular dystrophies targeting Ca2+ regulatory proteins.
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