101
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Lagrue E, Dogan C, De Antonio M, Audic F, Bach N, Barnerias C, Bellance R, Cances C, Chabrol B, Cuisset JM, Desguerre I, Durigneux J, Espil C, Fradin M, Héron D, Isapof A, Jacquin-Piques A, Journel H, Laroche-Raynaud C, Laugel V, Magot A, Manel V, Mayer M, Péréon Y, Perrier-Boeswillald J, Peudenier S, Quijano-Roy S, Ragot-Mandry S, Richelme C, Rivier F, Sabouraud P, Sarret C, Testard H, Vanhulle C, Walther-Louvier U, Gherardi R, Hamroun D, Bassez G. A large multicenter study of pediatric myotonic dystrophy type 1 for evidence-based management. Neurology 2019; 92:e852-e865. [DOI: 10.1212/wnl.0000000000006948] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2018] [Accepted: 10/18/2018] [Indexed: 12/18/2022] Open
Abstract
ObjectiveTo genotypically and phenotypically characterize a large pediatric myotonic dystrophy type 1 (DM1) cohort to provide a solid frame of data for future evidence-based health management.MethodsAmong the 2,697 patients with genetically confirmed DM1 included in the French DM-Scope registry, children were enrolled between January 2010 and February 2016 from 24 centers. Comprehensive cross-sectional analysis of most relevant qualitative and quantitative variables was performed.ResultsWe studied 314 children (52% females, with 55% congenital, 31% infantile, 14% juvenile form). The age at inclusion was inversely correlated with the CTG repeat length. The paternal transmission rate was higher than expected, especially in the congenital form (13%). A continuum of highly prevalent neurodevelopmental alterations was observed, including cognitive slowing (83%), attention deficit (64%), written language (64%), and spoken language (63%) disorders. Five percent exhibited autism spectrum disorders. Overall, musculoskeletal impairment was mild. Despite low prevalence, cardiorespiratory impairment could be life-threatening, and frequently occurred early in the first decade (25.9%). Gastrointestinal symptoms (27%) and cataracts (7%) were more frequent than expected, while endocrine or metabolic disorders were scarce.ConclusionsThe pedDM-Scope study details the main genotype and phenotype characteristics of the 3 DM1 pediatric subgroups. It highlights striking profiles that could be useful in health care management (including transition into adulthood) and health policy planning.
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102
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Sochala M, Porcher R, Stojkovic T, Bécane HM, Béhin A, Laforêt P, Bassez G, Leonard-Louis S, Eymard B, Furling D, Duboc D, Wahbi K. High Risk of Fatal and Nonfatal Venous Thromboembolism in Myotonic Dystrophy. Circulation 2018; 138:1169-1171. [PMID: 30354391 DOI: 10.1161/circulationaha.118.035035] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Maximilien Sochala
- Assistance Publique des Hôpitaux de Paris, Cochin Hospital, Cardiology Department, Centre de Référence de Pathologie Neuromusculaire Nord/Est/Ile de France, Paris-Descartes, Sorbonne Paris Cité University, France (M.S., D.D., K.W.)
| | - Raphaël Porcher
- Institut National de la Santé et de la Recherche Médicale (INSERM) U1153, 1 Place du Parvis Notre Dame, Paris, France (R.P.).,Université Paris Descartes-Sorbonne Paris Cité, France (R.P.).,Centre d'Epidémiologie Clinique, Hôpital Hôtel-Dieu, Assistance Publique des Hôpitaux de Paris, Paris, France (R.P.)
| | - Tanya Stojkovic
- Assistance Publique des Hôpitaux de Paris, Centre de Référence de Pathologie Neuromusculaire Nord/Est/Ile de France, Myology Institute, Neurology Department, Pitié-Salpêtrière Hospital, Paris, France (T.S., H.M.B., A.B., G.B., S.L.-L., D.D.)
| | - Henri Marc Bécane
- Assistance Publique des Hôpitaux de Paris, Centre de Référence de Pathologie Neuromusculaire Nord/Est/Ile de France, Myology Institute, Neurology Department, Pitié-Salpêtrière Hospital, Paris, France (T.S., H.M.B., A.B., G.B., S.L.-L., D.D.)
| | - Anthony Béhin
- Assistance Publique des Hôpitaux de Paris, Centre de Référence de Pathologie Neuromusculaire Nord/Est/Ile de France, Myology Institute, Neurology Department, Pitié-Salpêtrière Hospital, Paris, France (T.S., H.M.B., A.B., G.B., S.L.-L., D.D.)
| | - Pascal Laforêt
- Assistance Publique des Hôpitaux de Paris, Centre de Référence de Pathologie Neuromusculaire Nord/Est/Ile de France, Raymond Poincaré Hospital, Paris, France (P.L.).,INSERM U1179, END-ICAP, Université Versailles Saint-Quentin-en-Yvelines, Montigny-le-Bretonneux, France (P.L.)
| | - Guillaume Bassez
- Assistance Publique des Hôpitaux de Paris, Centre de Référence de Pathologie Neuromusculaire Nord/Est/Ile de France, Myology Institute, Neurology Department, Pitié-Salpêtrière Hospital, Paris, France (T.S., H.M.B., A.B., G.B., S.L.-L., D.D.).,Pierre et Marie Curie-Paris 6 University, France (G.B., B.E.)
| | - Sarah Leonard-Louis
- Assistance Publique des Hôpitaux de Paris, Centre de Référence de Pathologie Neuromusculaire Nord/Est/Ile de France, Myology Institute, Neurology Department, Pitié-Salpêtrière Hospital, Paris, France (T.S., H.M.B., A.B., G.B., S.L.-L., D.D.)
| | - Bruno Eymard
- Pierre et Marie Curie-Paris 6 University, France (G.B., B.E.)
| | - Denis Furling
- Sorbonne Universities UPMC Université Paris 06, INSERM, Centre National de la Recherche Scientifique, Centre de Recherche en Myologie, Institut de Myologie, Pitié-Salpêtrière Hospital, France (D.F.)
| | - Denis Duboc
- Assistance Publique des Hôpitaux de Paris, Cochin Hospital, Cardiology Department, Centre de Référence de Pathologie Neuromusculaire Nord/Est/Ile de France, Paris-Descartes, Sorbonne Paris Cité University, France (M.S., D.D., K.W.).,Assistance Publique des Hôpitaux de Paris, Centre de Référence de Pathologie Neuromusculaire Nord/Est/Ile de France, Myology Institute, Neurology Department, Pitié-Salpêtrière Hospital, Paris, France (T.S., H.M.B., A.B., G.B., S.L.-L., D.D.).,INSERM, Unité Mixte de Recherche 974, Paris, France (D.D.)
| | - Karim Wahbi
- Assistance Publique des Hôpitaux de Paris, Cochin Hospital, Cardiology Department, Centre de Référence de Pathologie Neuromusculaire Nord/Est/Ile de France, Paris-Descartes, Sorbonne Paris Cité University, France (M.S., D.D., K.W.).,INSERM Unit 970, Paris Cardiovascular Research Centre, France (K.W.)
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103
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Glineburg MR, Todd PK, Charlet-Berguerand N, Sellier C. Repeat-associated non-AUG (RAN) translation and other molecular mechanisms in Fragile X Tremor Ataxia Syndrome. Brain Res 2018; 1693:43-54. [PMID: 29453961 PMCID: PMC6010627 DOI: 10.1016/j.brainres.2018.02.006] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Revised: 01/31/2018] [Accepted: 02/02/2018] [Indexed: 11/11/2022]
Abstract
Fragile X-associated tremor/ataxia syndrome (FXTAS) is a late-onset inherited neurodegenerative disorder characterized by progressive intention tremor, gait ataxia and dementia associated with mild brain atrophy. The cause of FXTAS is a premutation expansion, of 55 to 200 CGG repeats localized within the 5'UTR of FMR1. These repeats are transcribed in the sense and antisense directions into mutants RNAs, which have increased expression in FXTAS. Furthermore, CGG sense and CCG antisense expanded repeats are translated into novel proteins despite their localization in putatively non-coding regions of the transcript. Here we focus on two proposed disease mechanisms for FXTAS: 1) RNA gain-of-function, whereby the mutant RNAs bind specific proteins and preclude their normal functions, and 2) repeat-associated non-AUG (RAN) translation, whereby translation through the CGG or CCG repeats leads to the production of toxic homopolypeptides, which in turn interfere with a variety of cellular functions. Here, we analyze the data generated to date on both of these potential molecular mechanisms and lay out a path forward for determining which factors drive FXTAS pathogenicity.
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Affiliation(s)
| | - Peter K Todd
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109, USA; Veteran's Affairs Medical Center, Ann Arbor, MI 48105, USA
| | - Nicolas Charlet-Berguerand
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U964, CNRS UMR7104, University of Strasbourg, 67400 Illkirch, France
| | - Chantal Sellier
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U964, CNRS UMR7104, University of Strasbourg, 67400 Illkirch, France.
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104
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RNA-mediated therapies in myotonic dystrophy. Drug Discov Today 2018; 23:2013-2022. [PMID: 30086404 DOI: 10.1016/j.drudis.2018.08.004] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2018] [Revised: 07/25/2018] [Accepted: 08/01/2018] [Indexed: 12/29/2022]
Abstract
Myotonic dystrophy 1 (DM1) is a multisystemic neuromuscular disease caused by a dominantly inherited 'CTG' repeat expansion in the gene encoding DM Protein Kinase (DMPK). The repeats are transcribed into mRNA, which forms hairpins and binds with high affinity to the Muscleblind-like (MBNL) family of proteins, sequestering them from their normal function. The loss of function of MBNL proteins causes numerous downstream effects, primarily the appearance of nuclear foci, mis-splicing, and ultimately myotonia and other clinical symptoms. Antisense and other RNA-mediated technologies have been applied to target toxic-repeat mRNA transcripts to restore MBNL protein function in DM1 models, such as cells and mice, and in humans. This technique has had promising results in DM1 therapeutics by alleviating pathogenic phenotypes.
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105
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Braz SO, Acquaire J, Gourdon G, Gomes-Pereira M. Of Mice and Men: Advances in the Understanding of Neuromuscular Aspects of Myotonic Dystrophy. Front Neurol 2018; 9:519. [PMID: 30050493 PMCID: PMC6050950 DOI: 10.3389/fneur.2018.00519] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2018] [Accepted: 06/12/2018] [Indexed: 12/26/2022] Open
Abstract
Intensive effort has been directed toward the modeling of myotonic dystrophy (DM) in mice, in order to reproduce human disease and to provide useful tools to investigate molecular and cellular pathogenesis and test efficient therapies. Mouse models have contributed to dissect the multifaceted impact of the DM mutation in various tissues, cell types and in a pleiotropy of pathways, through the expression of toxic RNA transcripts. Changes in alternative splicing, transcription, translation, intracellular RNA localization, polyadenylation, miRNA metabolism and phosphorylation of disease intermediates have been described in different tissues. Some of these events have been directly associated with specific disease symptoms in the skeletal muscle and heart of mice, offering the molecular explanation for individual disease phenotypes. In the central nervous system (CNS), however, the situation is more complex. We still do not know how the molecular abnormalities described translate into CNS dysfunction, nor do we know if the correction of individual molecular events will provide significant therapeutic benefits. The variability in model design and phenotypes described so far requires a thorough and critical analysis. In this review we discuss the recent contributions of mouse models to the understanding of neuromuscular aspects of disease, therapy development, and we provide a reflective assessment of our current limitations and pressing questions that remain unanswered.
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Affiliation(s)
- Sandra O Braz
- Laboratory CTGDM, INSERM UMR1163, Paris, France.,Institut Imagine, Université Paris Descartes-Sorbonne Paris Cité, Paris, France
| | - Julien Acquaire
- Laboratory CTGDM, INSERM UMR1163, Paris, France.,Institut Imagine, Université Paris Descartes-Sorbonne Paris Cité, Paris, France
| | - Geneviève Gourdon
- Laboratory CTGDM, INSERM UMR1163, Paris, France.,Institut Imagine, Université Paris Descartes-Sorbonne Paris Cité, Paris, France
| | - Mário Gomes-Pereira
- Laboratory CTGDM, INSERM UMR1163, Paris, France.,Institut Imagine, Université Paris Descartes-Sorbonne Paris Cité, Paris, France
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106
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Holdt LM, Kohlmaier A, Teupser D. Molecular functions and specific roles of circRNAs in the cardiovascular system. Noncoding RNA Res 2018; 3:75-98. [PMID: 30159442 PMCID: PMC6096412 DOI: 10.1016/j.ncrna.2018.05.002] [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: 11/23/2017] [Revised: 05/11/2018] [Accepted: 05/11/2018] [Indexed: 12/25/2022] Open
Abstract
As part of the superfamily of long noncoding RNAs, circular RNAs (circRNAs) are emerging as a new type of regulatory molecules that partake in gene expression control. Here, we review the current knowledge about circRNAs in cardiovascular disease. CircRNAs are not only associated with different types of cardiovascular disease, but they have also been identified as intracellular effector molecules for pathophysiological changes in cardiovascular tissues, and as cardiovascular biomarkers. This evidence is put in the context of the current understanding of general circRNA biogenesis and of known interactions of circRNAs with DNA, RNA, and proteins.
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Affiliation(s)
- Lesca M. Holdt
- Institute of Laboratory Medicine, University Hospital, LMU Munich, Germany
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107
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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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108
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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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109
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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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110
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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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111
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de Bruin RG, Rabelink TJ, van Zonneveld AJ, van der Veer EP. Emerging roles for RNA-binding proteins as effectors and regulators of cardiovascular disease. Eur Heart J 2018; 38:1380-1388. [PMID: 28064149 DOI: 10.1093/eurheartj/ehw567] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Accepted: 11/02/2016] [Indexed: 12/18/2022] Open
Abstract
The cardiovascular system comprises multiple cell types that possess the capacity to modulate their phenotype in response to acute or chronic injury. Transcriptional and post-transcriptional mechanisms play a key role in the regulation of remodelling and regenerative responses to damaged cardiovascular tissues. Simultaneously, insufficient regulation of cellular phenotype is tightly coupled with the persistence and exacerbation of cardiovascular disease. Recently, RNA-binding proteins such as Quaking, HuR, Muscleblind, and SRSF1 have emerged as pivotal regulators of these functional adaptations in the cardiovascular system by guiding a wide-ranging number of post-transcriptional events that dramatically impact RNA fate, including alternative splicing, stability, localization and translation. Moreover, homozygous disruption of RNA-binding protein genes is commonly associated with cardiac- and/or vascular complications. Here, we summarize the current knowledge on the versatile role of RNA-binding proteins in regulating the transcriptome during phenotype switching in cardiovascular health and disease. We also detail existing and potential DNA- and RNA-based therapeutic approaches that could impact the treatment of cardiovascular disease in the future.
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Affiliation(s)
- Ruben G de Bruin
- Einthoven Laboratory for Experimental Vascular Medicine, Leiden University Medical Center, Albinusdreef 2, Leiden 2300RC, The Netherlands.,Division of Nephrology, Department of Internal Medicine, Leiden University Medical Center, Albinusdreef 2, Leiden 2300RC, The Netherlands
| | - Ton J Rabelink
- Einthoven Laboratory for Experimental Vascular Medicine, Leiden University Medical Center, Albinusdreef 2, Leiden 2300RC, The Netherlands.,Division of Nephrology, Department of Internal Medicine, Leiden University Medical Center, Albinusdreef 2, Leiden 2300RC, The Netherlands
| | - Anton Jan van Zonneveld
- Einthoven Laboratory for Experimental Vascular Medicine, Leiden University Medical Center, Albinusdreef 2, Leiden 2300RC, The Netherlands.,Division of Nephrology, Department of Internal Medicine, Leiden University Medical Center, Albinusdreef 2, Leiden 2300RC, The Netherlands
| | - Eric P van der Veer
- Einthoven Laboratory for Experimental Vascular Medicine, Leiden University Medical Center, Albinusdreef 2, Leiden 2300RC, The Netherlands.,Division of Nephrology, Department of Internal Medicine, Leiden University Medical Center, Albinusdreef 2, Leiden 2300RC, The Netherlands
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112
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Spitalieri P, Talarico RV, Caioli S, Murdocca M, Serafino A, Girasole M, Dinarelli S, Longo G, Pucci S, Botta A, Novelli G, Zona C, Mango R, Sangiuolo F. Modelling the pathogenesis of Myotonic Dystrophy type 1 cardiac phenotype through human iPSC-derived cardiomyocytes. J Mol Cell Cardiol 2018; 118:95-109. [PMID: 29551391 DOI: 10.1016/j.yjmcc.2018.03.012] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Revised: 03/12/2018] [Accepted: 03/14/2018] [Indexed: 12/20/2022]
Abstract
Myotonic Dystrophy type 1 (DM1) is a multisystemic disease, autosomal dominant, caused by a CTG repeat expansion in DMPK gene. We assessed the appropriateness of patient-specific induced pluripotent stem cell-derived cardiomyocytes (CMs) as a model to recapitulate some aspects of the pathogenetic mechanism involving cardiac manifestations in DM1 patients. Once obtained in vitro, CMs have been characterized for their morphology and their functionality. CMs DM1 show intranuclear foci and transcript markers abnormally spliced respect to WT ones, as well as several irregularities in nuclear morphology, probably caused by an unbalanced lamin A/C ratio. Electrophysiological characterization evidences an abnormal profile only in CMs DM1 such that the administration of antiarrythmic drugs to these cells highlights even more the functional defect linked to the disease. Finally, Atomic Force Measurements reveal differences in the biomechanical behaviour of CMs DM1, in terms of frequencies and synchronicity of the beats. Altogether the complex phenotype described in this work, strongly reproduces some aspects of the human DM1 cardiac phenotype. Therefore, the present study provides an in vitro model suggesting novel insights into the mechanisms leading to the development of arrhythmogenesis and dilatative cardiomyopathy to consider when approaching to DM1 patients, especially for the risk assessment of sudden cardiac death (SCD). These data could be also useful in identifying novel biomarkers effective in clinical settings and patient-tailored therapies.
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Affiliation(s)
- Paola Spitalieri
- Dept of Biomedicine and Prevention, University of Rome "Tor Vergata", Rome, Italy
| | - Rosa V Talarico
- Dept of Biomedicine and Prevention, University of Rome "Tor Vergata", Rome, Italy
| | | | - Michela Murdocca
- Dept of Biomedicine and Prevention, University of Rome "Tor Vergata", Rome, Italy
| | | | | | | | | | - Sabina Pucci
- Dept of Biomedicine and Prevention, University of Rome "Tor Vergata", Rome, Italy
| | - Annalisa Botta
- Dept of Biomedicine and Prevention, University of Rome "Tor Vergata", Rome, Italy
| | - Giuseppe Novelli
- Dept of Biomedicine and Prevention, University of Rome "Tor Vergata", Rome, Italy
| | - Cristina Zona
- I.R.C.C.S. S. Lucia, Rome, Italy; Dept of Systems Medicine, University of Rome "Tor Vergata", Rome, Italy
| | | | - Federica Sangiuolo
- Dept of Biomedicine and Prevention, University of Rome "Tor Vergata", Rome, Italy.
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114
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Benoit-Pilven C, Marchet C, Chautard E, Lima L, Lambert MP, Sacomoto G, Rey A, Cologne A, Terrone S, Dulaurier L, Claude JB, Bourgeois CF, Auboeuf D, Lacroix V. Complementarity of assembly-first and mapping-first approaches for alternative splicing annotation and differential analysis from RNAseq data. Sci Rep 2018; 8:4307. [PMID: 29523794 PMCID: PMC5844962 DOI: 10.1038/s41598-018-21770-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Accepted: 01/30/2018] [Indexed: 11/08/2022] Open
Abstract
Genome-wide analyses estimate that more than 90% of multi exonic human genes produce at least two transcripts through alternative splicing (AS). Various bioinformatics methods are available to analyze AS from RNAseq data. Most methods start by mapping the reads to an annotated reference genome, but some start by a de novo assembly of the reads. In this paper, we present a systematic comparison of a mapping-first approach (FARLINE) and an assembly-first approach (KISSPLICE). We applied these methods to two independent RNAseq datasets and found that the predictions of the two pipelines overlapped (70% of exon skipping events were common), but with noticeable differences. The assembly-first approach allowed to find more novel variants, including novel unannotated exons and splice sites. It also predicted AS in recently duplicated genes. The mapping-first approach allowed to find more lowly expressed splicing variants, and splice variants overlapping repeats. This work demonstrates that annotating AS with a single approach leads to missing out a large number of candidates, many of which are differentially regulated across conditions and can be validated experimentally. We therefore advocate for the combined use of both mapping-first and assembly-first approaches for the annotation and differential analysis of AS from RNAseq datasets.
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Affiliation(s)
- Clara Benoit-Pilven
- Université de Lyon, ENS de Lyon, Université Claude Bernard, CNRS UMR 5239, INSERM U1210, Laboratory of Biology and Modelling of the Cell, 46 Allée d'Italie Site Jacques Monod, F-69007, Lyon, France
| | - Camille Marchet
- IRISA Inria Rennes Bretagne Atlantique CNRS UMR 6074, Université Rennes 1, GenScale team, Rennes, 263 Avenue Général Leclerc, Rennes, France
| | - Emilie Chautard
- Université de Lyon, ENS de Lyon, Université Claude Bernard, CNRS UMR 5239, INSERM U1210, Laboratory of Biology and Modelling of the Cell, 46 Allée d'Italie Site Jacques Monod, F-69007, Lyon, France
- Université de Lyon, F-69000, Lyon; Université Lyon 1; CNRS, UMR5558, Laboratoire de Biométrie et Biologie Evolutive, F-69622, Villeurbanne, EPI ERABLE - Inria Grenoble, Rhône-Alpes, France
| | - Leandro Lima
- Université de Lyon, F-69000, Lyon; Université Lyon 1; CNRS, UMR5558, Laboratoire de Biométrie et Biologie Evolutive, F-69622, Villeurbanne, EPI ERABLE - Inria Grenoble, Rhône-Alpes, France
| | - Marie-Pierre Lambert
- Université de Lyon, ENS de Lyon, Université Claude Bernard, CNRS UMR 5239, INSERM U1210, Laboratory of Biology and Modelling of the Cell, 46 Allée d'Italie Site Jacques Monod, F-69007, Lyon, France
| | - Gustavo Sacomoto
- Université de Lyon, F-69000, Lyon; Université Lyon 1; CNRS, UMR5558, Laboratoire de Biométrie et Biologie Evolutive, F-69622, Villeurbanne, EPI ERABLE - Inria Grenoble, Rhône-Alpes, France
| | - Amandine Rey
- Université de Lyon, ENS de Lyon, Université Claude Bernard, CNRS UMR 5239, INSERM U1210, Laboratory of Biology and Modelling of the Cell, 46 Allée d'Italie Site Jacques Monod, F-69007, Lyon, France
| | - Audric Cologne
- Université de Lyon, F-69000, Lyon; Université Lyon 1; CNRS, UMR5558, Laboratoire de Biométrie et Biologie Evolutive, F-69622, Villeurbanne, EPI ERABLE - Inria Grenoble, Rhône-Alpes, France
| | - Sophie Terrone
- Université de Lyon, ENS de Lyon, Université Claude Bernard, CNRS UMR 5239, INSERM U1210, Laboratory of Biology and Modelling of the Cell, 46 Allée d'Italie Site Jacques Monod, F-69007, Lyon, France
| | - Louis Dulaurier
- Université de Lyon, ENS de Lyon, Université Claude Bernard, CNRS UMR 5239, INSERM U1210, Laboratory of Biology and Modelling of the Cell, 46 Allée d'Italie Site Jacques Monod, F-69007, Lyon, France
| | - Jean-Baptiste Claude
- Université de Lyon, ENS de Lyon, Université Claude Bernard, CNRS UMR 5239, INSERM U1210, Laboratory of Biology and Modelling of the Cell, 46 Allée d'Italie Site Jacques Monod, F-69007, Lyon, France
| | - Cyril F Bourgeois
- Université de Lyon, ENS de Lyon, Université Claude Bernard, CNRS UMR 5239, INSERM U1210, Laboratory of Biology and Modelling of the Cell, 46 Allée d'Italie Site Jacques Monod, F-69007, Lyon, France
| | - Didier Auboeuf
- Université de Lyon, ENS de Lyon, Université Claude Bernard, CNRS UMR 5239, INSERM U1210, Laboratory of Biology and Modelling of the Cell, 46 Allée d'Italie Site Jacques Monod, F-69007, Lyon, France.
| | - Vincent Lacroix
- Université de Lyon, F-69000, Lyon; Université Lyon 1; CNRS, UMR5558, Laboratoire de Biométrie et Biologie Evolutive, F-69622, Villeurbanne, EPI ERABLE - Inria Grenoble, Rhône-Alpes, France.
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115
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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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116
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Chong-Nguyen C, Wahbi K, Algalarrondo V, Bécane HM, Radvanyi-Hoffman H, Arnaud P, Furling D, Lazarus A, Bassez G, Béhin A, Fayssoil A, Laforêt P, Stojkovic T, Eymard B, Duboc D. Association Between Mutation Size and Cardiac Involvement in Myotonic Dystrophy Type 1: An Analysis of the DM1-Heart Registry. ACTA ACUST UNITED AC 2018; 10:CIRCGENETICS.116.001526. [PMID: 28611030 DOI: 10.1161/circgenetics.116.001526] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Accepted: 03/03/2017] [Indexed: 11/16/2022]
Abstract
BACKGROUND In myotonic dystrophy type 1, the association between mutation size (CTG expansion) and the severity of cardiac involvement is controversial. METHODS AND RESULTS We selected 855 patients with myotonic dystrophy type 1 (women, 51%; median age, 37 years), with genetic testing performed at the moment of their initial cardiac evaluation, out of 1014 patients included in the Myotonic Dystrophy Type 1-Heart Registry between January 2000 and December 2015. We studied the association between CTG expansion size and other baseline characteristics and (1) cardiac involvement at baseline and (2) the incidence of death, sudden death, and other cardiac adverse events. At initial presentation, the median CTG expansion size was 530 (interquartile range, 300-830). In multivariate analysis, larger expansions were associated with the presence at baseline of conduction defects on the ECG and left ventricular systolic dysfunction. In a median 11.5 years of follow-up period, 210 patients died (25%), including 32 suddenly (4%). Supraventricular arrhythmias developed over lifetime in 166 patients (19%), sustained ventricular tachyarrhythmias in 17 (2%), and permanent pacemakers were implanted in 181 (21%). In Cox regression analyses, larger CTG expansions were significantly associated with (1) total death, sudden death, and pacemaker implantation in a model, including CTG expansion size, age, sex, diabetes mellitus, and (2) all end points except sudden death in a model including all baseline characteristics. CONCLUSIONS The size of the CTG expansion in the blood of myotonic dystrophy type 1 patients is associated with total and sudden deaths, conduction defects, left ventricular dysfunction, and supraventricular arrhythmias. CLINICAL TRIAL REGISTRATION URL: https://www.clinicaltrials.gov. Unique Identifier: NCT01136330.
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117
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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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118
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Tadros R, Nannenberg EA, Lieve KV, Škorić-Milosavljević D, Lahrouchi N, Lekanne Deprez RH, Vendrik J, Reckman YJ, Postema PG, Amin AS, Bezzina CR, Wilde AA, Tan HL. Yield and Pitfalls of Ajmaline Testing in the Evaluation of Unexplained Cardiac Arrest and Sudden Unexplained Death. JACC Clin Electrophysiol 2017; 3:1400-1408. [DOI: 10.1016/j.jacep.2017.04.005] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Revised: 03/30/2017] [Accepted: 04/13/2017] [Indexed: 01/25/2023]
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119
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Koene RJ, Adkisson WO, Benditt DG. Syncope and the risk of sudden cardiac death: Evaluation, management, and prevention. J Arrhythm 2017; 33:533-544. [PMID: 29255498 PMCID: PMC5728985 DOI: 10.1016/j.joa.2017.07.005] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Revised: 06/04/2017] [Accepted: 07/04/2017] [Indexed: 12/17/2022] Open
Abstract
Syncope is a clinical syndrome defined as a relatively brief self-limited transient loss of consciousness (TLOC) caused by a period of inadequate cerebral nutrient flow. Most often the trigger is an abrupt drop of systemic blood pressure. True syncope must be distinguished from other common non-syncope conditions in which real or apparent TLOC may occur such as seizures, concussions, or accidental falls. The causes of syncope are diverse, but in most instances, are relatively benign (e.g., reflex and orthostatic faints) with the main risks being accidents and/or injury. However, in some instances, syncope may be due to more worrisome conditions (particularly those associated with cardiac structural disease or channelopathies); in such circumstances, syncope may be an indicator of increased morbidity and mortality risk, including sudden cardiac death (SCD). Establishing an accurate basis for the etiology of syncope is crucial in order to initiate effective therapy. In this review, we focus primarily on the causes of syncope that are associated with increased SCD risk (i.e., sudden arrhythmic cardiac death), and the management of these patients. In addition, we discuss the limitations of our understanding of SCD in relation to syncope, and propose future studies that may ultimately address how to improve outcomes of syncope patients and reduce SCD risk.
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Affiliation(s)
| | | | - David G. Benditt
- From the Cardiac Arrhythmia Center, Division of Cardiovascular Medicine, Department of Medicine, University of Minnesota Medical School, Minneapolis, MN, USA
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Giudice J, Loehr JA, Rodney GG, Cooper TA. Alternative Splicing of Four Trafficking Genes Regulates Myofiber Structure and Skeletal Muscle Physiology. Cell Rep 2017; 17:1923-1933. [PMID: 27851958 DOI: 10.1016/j.celrep.2016.10.072] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2016] [Revised: 09/02/2016] [Accepted: 10/20/2016] [Indexed: 11/16/2022] Open
Abstract
During development, transcriptional and post-transcriptional networks are coordinately regulated to drive organ maturation. Alternative splicing contributes by producing temporal-specific protein isoforms. We previously found that genes undergoing splicing transitions during mouse postnatal heart development are enriched for vesicular trafficking and membrane dynamics functions. Here, we show that adult trafficking isoforms are also expressed in adult skeletal muscle and hypothesize that striated muscle utilizes alternative splicing to generate specific isoforms required for function of adult tissue. We deliver morpholinos into flexor digitorum brevis muscles in adult mice to redirect splicing of four trafficking genes to the fetal isoforms. The splicing switch results in multiple structural and functional defects, including transverse tubule (T-tubule) disruption and dihydropyridine receptor alpha (DHPR) and Ryr1 mislocalization, impairing excitation-contraction coupling, calcium handling, and force generation. The results demonstrate a previously unrecognized role for trafficking functions in adult muscle tissue homeostasis and a specific requirement for the adult splice variants.
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Affiliation(s)
- Jimena Giudice
- Department of Pathology & Immunology, Baylor College of Medicine, Houston, TX 77030, USA; Department of Cell Biology and 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, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
| | - James A Loehr
- Department of Molecular Physiology & Biophysics, Baylor College of Medicine, Houston, TX 77030, USA
| | - George G Rodney
- Department of Molecular Physiology & Biophysics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Thomas A Cooper
- Department of Pathology & Immunology, Baylor College of Medicine, Houston, TX 77030, USA; Department of Molecular Physiology & Biophysics, Baylor College of Medicine, Houston, TX 77030, USA; Department of Molecular & Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA.
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Peng J, Ou Q, Wu X, Zhang R, Zhao Q, Jiang W, Lu Z, Wan D, Pan Z, Fang Y. Expression of voltage-gated sodium channel Nav1.5 in non-metastatic colon cancer and its associations with estrogen receptor (ER)-β expression and clinical outcomes. CHINESE JOURNAL OF CANCER 2017; 36:89. [PMID: 29122010 PMCID: PMC5679318 DOI: 10.1186/s40880-017-0253-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Accepted: 10/21/2017] [Indexed: 12/21/2022]
Abstract
Background Voltage-gated sodium channel 1.5 (Nav1.5) potentially promotes the migratory and invasive behaviors of colon cancer cells. Hitherto, the prognostic significance of Nav1.5 expression remains undetermined. The present study aimed to explore the associations of Nav1.5 expression with clinical outcomes and estrogen receptor-β (ER-β) expression in non-metastatic colon cancer patients receiving radical resection. Methods A total of 269 consecutive patients with pathologically confirmed stages I–III colon cancer who underwent radical resection were selected. Nav1.5 and ER-β expression was detected by using immunohistochemistry (IHC) on tissue microarray constructed from paraffin-embedded specimens. IHC score was determined according to the percentage and intensity of positively stained cells. Statistical analysis was performed with the X-tile method, k coefficient, Chi square test or Fisher’s exact test, logistic regression, log-rank test, and Cox proportional hazards models. Results We found that Nav1.5 was commonly expressed in tumor tissues with higher mean IHC score as compared with matched tumor-adjacent normal tissues (5.1 ± 3.5 vs. 3.5 ± 2.7, P < 0.001). The high expression of Nav1.5 in colon cancer tissues was associated with high preoperative carcinoembryonic antigen level [odds ratio (OR) = 2.980; 95% confidential interval (CI) 1.163–7.632; P = 0.023] and high ER-β expression (OR = 2.808; 95% CI 1.243–6.343; P = 0.013). Log-rank test results showed that high Nav1.5 expression contributed to a low 5-year disease-free survival (DFS) rate in colon cancer patients (77.2% vs. 92.1%, P = 0.048), especially in patients with high ER-β expression tumor (76.2% vs. 91.3%, P = 0.032). Analysis with Cox proportional hazards model demonstrated that high Nav1.5 expression [hazard ratio (HR) = 2.738; 95% CI 1.100–6.819; P = 0.030] and lymph node metastasis (HR = 2.633; 95% CI 1.632–4.248; P < 0.001) were prognostic factors for unfavorable DFS in colon cancer patients. Conclusions High expression of Nav1.5 was associated with high expression of ER-β and indicated unfavorable oncologic prognosis in patients with non-metastatic colon cancer.
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Affiliation(s)
- Jianhong Peng
- Department of Colorectal Surgery, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, 651 Dongfeng Road East, Guangzhou, 510060, Guangdong, P. R. China
| | - Qingjian Ou
- Department of Colorectal Surgery, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, 651 Dongfeng Road East, Guangzhou, 510060, Guangdong, P. R. China.,Department of Experimental Research, Sun Yat-sen University Cancer Center, Guangzhou, 510060, Guangdong, P. R. China
| | - Xiaojun Wu
- Department of Colorectal Surgery, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, 651 Dongfeng Road East, Guangzhou, 510060, Guangdong, P. R. China
| | - Rongxin Zhang
- Department of Colorectal Surgery, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, 651 Dongfeng Road East, Guangzhou, 510060, Guangdong, P. R. China
| | - Qian Zhao
- Department of Statistics, School of Public Health, Guangzhou Medical University, Guangzhou, 510182, Guangdong, P. R. China
| | - Wu Jiang
- Department of Colorectal Surgery, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, 651 Dongfeng Road East, Guangzhou, 510060, Guangdong, P. R. China
| | - Zhenhai Lu
- Department of Colorectal Surgery, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, 651 Dongfeng Road East, Guangzhou, 510060, Guangdong, P. R. China
| | - Desen Wan
- Department of Colorectal Surgery, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, 651 Dongfeng Road East, Guangzhou, 510060, Guangdong, P. R. China
| | - Zhizhong Pan
- Department of Colorectal Surgery, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, 651 Dongfeng Road East, Guangzhou, 510060, Guangdong, P. R. China.
| | - Yujing Fang
- Department of Colorectal Surgery, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, 651 Dongfeng Road East, Guangzhou, 510060, Guangdong, P. R. China. .,Department of Experimental Research, Sun Yat-sen University Cancer Center, Guangzhou, 510060, Guangdong, P. R. China.
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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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Gene Expression Networks in the Murine Pulmonary Myocardium Provide Insight into the Pathobiology of Atrial Fibrillation. G3-GENES GENOMES GENETICS 2017; 7:2999-3017. [PMID: 28720711 PMCID: PMC5592927 DOI: 10.1534/g3.117.044651] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The pulmonary myocardium is a muscular coat surrounding the pulmonary and caval veins. Although its definitive physiological function is unknown, it may have a pathological role as the source of ectopic beats initiating atrial fibrillation. How the pulmonary myocardium gains pacemaker function is not clearly defined, although recent evidence indicates that changed transcriptional gene expression networks are at fault. The gene expression profile of this distinct cell type in situ was examined to investigate underlying molecular events that might contribute to atrial fibrillation. Via systems genetics, a whole-lung transcriptome data set from the BXD recombinant inbred mouse resource was analyzed, uncovering a pulmonary cardiomyocyte gene network of 24 transcripts, coordinately regulated by chromosome 1 and 2 loci. Promoter enrichment analysis and interrogation of publicly available ChIP-seq data suggested that transcription of this gene network may be regulated by the concerted activity of NKX2-5, serum response factor, myocyte enhancer factor 2, and also, at a post-transcriptional level, by RNA binding protein motif 20. Gene ontology terms indicate that this gene network overlaps with molecular markers of the stressed heart. Therefore, we propose that perturbed regulation of this gene network might lead to altered calcium handling, myocyte growth, and contractile force contributing to the aberrant electrophysiological properties observed in atrial fibrillation. We reveal novel molecular interactions and pathways representing possible therapeutic targets for atrial fibrillation. In addition, we highlight the utility of recombinant inbred mouse resources in detecting and characterizing gene expression networks of relatively small populations of cells that have a pathological significance.
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Veerman CC, Mengarelli I, Lodder EM, Kosmidis G, Bellin M, Zhang M, Dittmann S, Guan K, Wilde AAM, Schulze-Bahr E, Greber B, Bezzina CR, Verkerk AO. Switch From Fetal to Adult SCN5A Isoform in Human Induced Pluripotent Stem Cell-Derived Cardiomyocytes Unmasks the Cellular Phenotype of a Conduction Disease-Causing Mutation. J Am Heart Assoc 2017; 6:JAHA.116.005135. [PMID: 28739862 PMCID: PMC5586268 DOI: 10.1161/jaha.116.005135] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Background Human induced pluripotent stem cell–derived cardiomyocytes (hiPSC‐CMs) can recapitulate features of ion channel mutations causing inherited rhythm disease. However, the lack of maturity of these cells is considered a significant limitation of the model. Prolonged culture of hiPSC‐CMs promotes maturation of these cells. We studied the electrophysiological effects of the I230T mutation in the sodium channel gene SCN5A in hiPSC‐CMs generated from a homozygous (I230Thomo) and a heterozygous (I230Thet) individual from a family with recessive cardiac conduction disease. Since the I230T mutation occurs in the developmentally regulated “adult” isoform of SCN5A, we investigated the relationship between the expression fraction of the adult SCN5A isoform and the electrophysiological phenotype at different time points in culture. Methods and Results After a culture period of 20 days, sodium current (INa) was mildly reduced in I230Thomo hiPSC‐CMs compared with control hiPSC‐CMs, while I230Thet hiPSC‐CMs displayed no reduction in INa. This coincided with a relatively high expression fraction of the “fetal” SCN5A isoform compared with the adult isoform as measured by quantitative polymerase chain reaction. Following prolonged culture to 66 days, the fraction of adult SCN5A isoform increased; this was paralleled by a marked decrease in INa in I230Thomo hiPSC‐CMs, in line with the severe clinical phenotype in homozygous patients. At this time in culture, I230Thet hiPSC‐CMs displayed an intermediate loss of INa, compatible with a gene dosage effect. Conclusions Prolonged culture of hiPSC‐CMs leads to an increased expression fraction of the adult sodium channel isoform. This new aspect of electrophysiological immaturity should be taken into account in studies that focus on the effects of SCN5A mutations in hiPSC‐CMs.
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Affiliation(s)
- Christiaan C Veerman
- Department of Experimental and Clinical Cardiology, Heart Center, Academic Medical Center, Amsterdam, The Netherlands
| | - Isabella Mengarelli
- Department of Experimental and Clinical Cardiology, Heart Center, Academic Medical Center, Amsterdam, The Netherlands
| | - Elisabeth M Lodder
- Department of Experimental and Clinical Cardiology, Heart Center, Academic Medical Center, Amsterdam, The Netherlands
| | - Georgios Kosmidis
- Department of Anatomy and Embryology, Leiden University Medical Center, Leiden, The Netherlands
| | - Milena Bellin
- Department of Anatomy and Embryology, Leiden University Medical Center, Leiden, The Netherlands
| | - Miao Zhang
- Human Pluripotent Stem Cell Laboratory, Max Planck Institute for Molecular Biomedicine, Münster, Germany.,Chemical Genomics Centre of the Max Planck Society, Dortmund, Germany
| | - Sven Dittmann
- Department of Cardiovascular Medicine, Institute for Genetics of Heart Diseases, University Hospital Münster, Münster, Germany
| | - Kaomei Guan
- Department of Pharmacology and Toxicology, Dresden University of Technology, Dresden, Germany
| | - Arthur A M Wilde
- Department of Experimental and Clinical Cardiology, Heart Center, Academic Medical Center, Amsterdam, The Netherlands
| | - Eric Schulze-Bahr
- Department of Cardiovascular Medicine, Institute for Genetics of Heart Diseases, University Hospital Münster, Münster, Germany
| | - Boris Greber
- Human Pluripotent Stem Cell Laboratory, Max Planck Institute for Molecular Biomedicine, Münster, Germany.,Chemical Genomics Centre of the Max Planck Society, Dortmund, Germany
| | - Connie R Bezzina
- Department of Experimental and Clinical Cardiology, Heart Center, Academic Medical Center, Amsterdam, The Netherlands
| | - Arie O Verkerk
- Department of Experimental and Clinical Cardiology, Heart Center, Academic Medical Center, Amsterdam, The Netherlands .,Department of Anatomy, Embryology and Physiology, Academic Medical Center, Amsterdam, The Netherlands
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125
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Liavas A, Lignani G, Schorge S. Conservation of alternative splicing in sodium channels reveals evolutionary focus on release from inactivation and structural insights into gating. J Physiol 2017. [PMID: 28621020 PMCID: PMC5811987 DOI: 10.1113/jp274693] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Key points Sodium channels are critical for supporting fast action potentials in neurons; even mutations which cause small changes in sodium channel activity can have devastating consequences for the function of the nervous system. Alternative splicing also changes the activity of sodium channels, and while it is highly conserved, it is not known whether the functional role of this splicing is also conserved. Our data reveal that splicing has a highly conserved impact on the availability of sodium channels during trains of rapid stimulations, and suggest that in one mammalian channel, Nav1.1 encoded by SCN1A, the increased availability of one splice variant is detrimental. A model reproducing the effects of splicing on channel behaviour suggests that the voltage sensor in the first domain is a rate limiting step for release of the inactivation domain, and highlights the functional specialization of channel domains.
Abstract Voltage‐gated sodium channels are critical for neuronal activity, and highly intolerant to variation. Even mutations that cause subtle changes in the activity these channels are sufficient to cause devastating inherited neurological diseases, such as epilepsy and pain. However, these channels do vary in healthy tissue. Alternative splicing modifies sodium channels, but the functional relevance and adaptive significance of this splicing remain poorly understood. Here we use a conserved alternate exon encoding part of the first domain of sodium channels to compare how splicing modifies different channels, and to ask whether the functional consequences of this splicing have been preserved in different genes. Although the splicing event is highly conserved, one splice variant has been selectively removed from Nav1.1 in multiple mammalian species, suggesting that the functional variation in Nav1.1 is less well tolerated. We show for three human channels (Nav1.1, Nav1.2 and Nav1.7) that splicing modifies the return from inactivated to deactivated states, and the differences between splice variants are occluded by antiepileptic drugs that bind to and stabilize inactivated states. A model based on structural data can replicate these changes, and indicates that splicing may exploit a distinct role of the first domain to change channel availability, and that the first domain of all three sodium channels plays a role in determining the rate at which the inactivation domain dissociates. Taken together, our data suggest that the stability of inactivated states is under tight evolutionary control, but that in Nav1.1 faster recovery from inactivation is associated with negative selection in mammals. Sodium channels are critical for supporting fast action potentials in neurons; even mutations which cause small changes in sodium channel activity can have devastating consequences for the function of the nervous system. Alternative splicing also changes the activity of sodium channels, and while it is highly conserved, it is not known whether the functional role of this splicing is also conserved. Our data reveal that splicing has a highly conserved impact on the availability of sodium channels during trains of rapid stimulations, and suggest that in one mammalian channel, Nav1.1 encoded by SCN1A, the increased availability of one splice variant is detrimental. A model reproducing the effects of splicing on channel behaviour suggests that the voltage sensor in the first domain is a rate limiting step for release of the inactivation domain, and highlights the functional specialization of channel domains.
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Affiliation(s)
- A Liavas
- Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, London, WC1N 3BG, UK
| | - G Lignani
- Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, London, WC1N 3BG, UK
| | - S Schorge
- Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, London, WC1N 3BG, UK
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126
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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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127
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Wheeler MT. Repeats and Survival in Myotonic Dystrophy Type 1. CIRCULATION. CARDIOVASCULAR GENETICS 2017; 10:CIRCGENETICS.117.001783. [PMID: 28611033 DOI: 10.1161/circgenetics.117.001783] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Affiliation(s)
- Matthew T Wheeler
- From the Center for Inherited Cardiovascular Diseases, Division of Cardiovascular Medicine, Stanford University School of Medicine and Center for Undiagnosed Diseases, Stanford University, Stanford, CA.
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128
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Alternative splicing as a regulator of development and tissue identity. Nat Rev Mol Cell Biol 2017; 18:437-451. [PMID: 28488700 DOI: 10.1038/nrm.2017.27] [Citation(s) in RCA: 794] [Impact Index Per Article: 113.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Alternative splicing of eukaryotic transcripts is a mechanism that enables cells to generate vast protein diversity from a limited number of genes. The mechanisms and outcomes of alternative splicing of individual transcripts are relatively well understood, and recent efforts have been directed towards studying splicing networks. It has become apparent that coordinated splicing networks regulate tissue and organ development, and that alternative splicing has important physiological functions in different developmental processes in humans.
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129
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Chou CC, Chang PC, Wei YC, Lee KY. Optical Mapping Approaches on Muscleblind-Like Compound Knockout Mice for Understanding Mechanistic Insights Into Ventricular Arrhythmias in Myotonic Dystrophy. J Am Heart Assoc 2017; 6:JAHA.116.005191. [PMID: 28416514 PMCID: PMC5533016 DOI: 10.1161/jaha.116.005191] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Background Cardiac arrhythmias are common causes of death in patients with myotonic dystrophy (dystrophia myotonica [DM]). Evidence shows that atrial tachyarrhythmia is an independent risk factor for sudden death; however, the relationship is unclear. Methods and Results Control wild‐type (Mbnl1+/+; Mbnl2+/+) and DM mutant (Mbnl1−/−; Mbnl2+/−) mice were generated by crossing double heterozygous knockout (Mbnl1+/−; Mbnl2+/−) mice. In vivo electrophysiological study and optical mapping technique were performed to investigate mechanisms of ventricular tachyarrhythmias. Transmission electron microscopy scanning was performed for myocardium ultrastructural analysis. DM mutant mice were more vulnerable to anesthesia medications and program electrical pacing: 2 of 12 mice had sudden apnea and cardiac arrest during premedication of general anesthesia; 9 of the remaining 10 had atrial tachycardia and/or atrioventricular block, but none of the wild‐type mice had spontaneous arrhythmias; and 9 of 10 mice had pacing‐induced ventricular tachyarrhythmias, but only 1 of 14 of the wild‐type mice. Optical mapping studies revealed prolonged action potential duration, slower conduction velocity, and steeper conduction velocity restitution curves in the DM mutant mice than in the wild‐type group. Spatially discordant alternans was more easily inducible in DM mutant than wild‐type mice. Transmission electron microscopy showed disarranged myofibrils with enlarged vacuole‐occupying mitochondria in the DM mutant group. Conclusions This DM mutant mouse model presented with clinical myofibril ultrastructural abnormality and cardiac arrhythmias, including atrial tachyarrhythmias, atrioventricular block, and ventricular tachyarrhythmias. Optical mapping studies revealed prolonged action potential duration and slow conduction velocity in the DM mice, leading to vulnerability of spatially discordant alternans and ventricular arrhythmia induction to pacing.
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Affiliation(s)
- Chung-Chuan Chou
- Department of Cardiology, Chang Gung Memorial Hospital, Linkou, Taiwan
- College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Po-Cheng Chang
- Department of Cardiology, Chang Gung Memorial Hospital, Linkou, Taiwan
- College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Yi-Chia Wei
- Department of Neurology, Chang Gung Memorial Hospital, Keelung, Taiwan
| | - Kuang-Yung Lee
- Department of Neurology, Chang Gung Memorial Hospital, Keelung, Taiwan
- College of Medicine, Chang Gung University, Taoyuan, Taiwan
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130
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Nutter CA, Jaworski E, Verma SK, Perez-Carrasco Y, Kuyumcu-Martinez MN. Developmentally regulated alternative splicing is perturbed in type 1 diabetic skeletal muscle. Muscle Nerve 2017; 56:744-749. [PMID: 28164326 DOI: 10.1002/mus.25599] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Revised: 01/19/2017] [Accepted: 01/31/2017] [Indexed: 12/28/2022]
Abstract
INTRODUCTION Type 1 diabetic patients can develop skeletal muscle weakness and atrophy by molecular mechanisms that are not well understood. Alternative splicing (AS) is critical for gene expression in the skeletal muscle, and its dysregulation is implicated in muscle weakness and atrophy. Therefore, we investigated whether AS patterns are affected in type 1 diabetic skeletal muscle contributing to skeletal muscle defects. METHODS AS patterns were determined by reverse transcription-polymerase chain reaction and levels of RNA binding proteins were assessed by Western blot in type 1 diabetic mouse skeletal muscle and during normal mouse skeletal muscle development. RESULTS Five genes with critical functions in the skeletal muscle are misspliced in type 1 diabetic skeletal muscle, resembling their AS patterns at embryonic stages. AS of these genes undergoes dramatic transitions during skeletal muscle development, correlating with changes in specific RNA binding proteins. CONCLUSION Embryonic spliced variants are inappropriately expressed in type 1 diabetic skeletal muscle. Muscle Nerve 56: 744-749, 2017.
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Affiliation(s)
- Curtis A Nutter
- Biochemistry and Molecular Biology, University of Texas Medical Branch, 301 University Boulevard, Galveston, Texas, 77555, USA
| | - Elizabeth Jaworski
- Biochemistry and Molecular Biology, University of Texas Medical Branch, 301 University Boulevard, Galveston, Texas, 77555, USA
| | - Sunil K Verma
- Biochemistry and Molecular Biology, University of Texas Medical Branch, 301 University Boulevard, Galveston, Texas, 77555, USA
| | | | - Muge N Kuyumcu-Martinez
- Biochemistry and Molecular Biology, University of Texas Medical Branch, 301 University Boulevard, Galveston, Texas, 77555, USA.,Neuroscience and Cell Biology, University of Texas Medical Branch, Galveston, Texas, USA.,Institute for Translational Sciences University of Texas Medical Branch, Galveston, Texas, USA
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Wahbi K, Babuty D, Probst V, Wissocque L, Labombarda F, Porcher R, Bécane HM, Lazarus A, Béhin A, Laforêt P, Stojkovic T, Clementy N, Dussauge AP, Gourraud JB, Pereon Y, Lacour A, Chapon F, Milliez P, Klug D, Eymard B, Duboc D. Incidence and predictors of sudden death, major conduction defects and sustained ventricular tachyarrhythmias in 1388 patients with myotonic dystrophy type 1. Eur Heart J 2017; 38:751-758. [PMID: 27941019 DOI: 10.1093/eurheartj/ehw569] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Accepted: 11/03/2016] [Indexed: 08/27/2023] Open
Abstract
AIMS To describe the incidence and identify predictors of sudden death (SD), major conduction defects and sustained ventricular tachyarrhythmias (VTA) in myotonic dystrophy type 1 (DM1). METHODS AND RESULTS We retrospectively enrolled 1388 adults with DM1 referred to six French medical centres between January 2000 and October 2013. We confirmed their vital status, classified all deaths, and determined the incidence of major conduction defects requiring permanent pacing and sustained VTA. We searched for predictors of overall survival, SD, major conduction defects, and sustained VTA by Cox regression analysis. Over a median 10-year follow-up, 253 (18.2%) patients died, 39 (3.6%) suddenly. Analysis of the cardiac rhythm at the time of the 39 SD revealed sustained VTA in 9, asystole in 5, complete atrioventricular block in 1 and electromechanical dissociation in two patients. Non-cardiac causes were identified in the five patients with SD who underwent autopsies. Major conduction defects developed in 143 (19.3%) and sustained VTA in 26 (2.3%) patients. By Cox regression analysis, age, family history of SD and left bundle branch block were independent predictors of SD, while age, male sex, electrocardiographic conduction abnormalities, syncope, and atrial fibrillation were independent predictors of major conduction defects; non-sustained VTA was the only predictor of sustained VTA. CONCLUSIONS SD was a frequent mode of death in DM1, with multiple mechanisms involved. Major conduction defects were by far more frequent than sustained VTA, whose only independent predictor was a personal history of non-sustained VTA. ClinicalTrials.gov no: NCT01136330.
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Affiliation(s)
- Karim Wahbi
- APHP, Cochin Hospital, Cardiology Department, Paris-Descartes, Sorbonne Paris Cité University, Paris, France
- APHP, Centre de Référence de pathologie neuromusculaire Paris-Est, Myology Institute, Neurology Department, Pitié-Salpêtrière Hospital, Paris, France
- Inserm, UMRS 974, Paris, France
| | - Dominique Babuty
- Cardiology Department, Université François Rabelais, CHU Tours, France
| | - Vincent Probst
- INSERM, UMR1087, Université de Nantes, L'Institut du Thorax, CHU de Nantes, CIC, Centre de référence pour la prise en charge des maladies rythmiques héréditaires de Nantes, Nantes, France
| | | | | | - Raphaël Porcher
- INSERM U1153, 1 Place du Parvis Notre Dame, 75004 Paris, France; Université Paris Descartes - Sorbonne Paris Cité, Paris, France; Centre d'Epidémiologie Clinique, Hôpital Hôtel-Dieu, APHP, Paris, France
| | - Henri Marc Bécane
- APHP, Centre de Référence de pathologie neuromusculaire Paris-Est, Myology Institute, Neurology Department, Pitié-Salpêtrière Hospital, Paris, France
| | | | - Anthony Béhin
- APHP, Centre de Référence de pathologie neuromusculaire Paris-Est, Myology Institute, Neurology Department, Pitié-Salpêtrière Hospital, Paris, France
| | - Pascal Laforêt
- APHP, Centre de Référence de pathologie neuromusculaire Paris-Est, Myology Institute, Neurology Department, Pitié-Salpêtrière Hospital, Paris, France
- Pierre et Marie Curie-Paris 6 University, Paris, France
| | - Tanya Stojkovic
- APHP, Centre de Référence de pathologie neuromusculaire Paris-Est, Myology Institute, Neurology Department, Pitié-Salpêtrière Hospital, Paris, France
| | - Nicolas Clementy
- Cardiology Department, Université François Rabelais, CHU Tours, France
| | - Aurélie Pattier Dussauge
- INSERM, UMR1087, Université de Nantes, L'Institut du Thorax, CHU de Nantes, CIC, Centre de référence pour la prise en charge des maladies rythmiques héréditaires de Nantes, Nantes, France
- Laboratoire d'Explorations Fonctionnelles, CHU de Nantes, Nantes, France
| | - Jean Baptiste Gourraud
- INSERM, UMR1087, Université de Nantes, L'Institut du Thorax, CHU de Nantes, CIC, Centre de référence pour la prise en charge des maladies rythmiques héréditaires de Nantes, Nantes, France
| | - Yann Pereon
- Centre de Référence des Maladies Neuromusculaires Rares de l'Enfant et de l'Adulte Nantes-Angers, CHU de Nantes, Nantes, France
| | - Arnaud Lacour
- Clinique neurologique et centre de référence des maladies rares neuromusculaires, hôpital Roger-Salengro, CHRU de Lille, rue Emile-Laine, Lille, France
| | - Françoise Chapon
- Centre de compétences des pathologies neuromusculaires, CHU de Caen, Caen, France
| | | | - Didier Klug
- Cardiologie A, University Hospital, Lille, France
| | - Bruno Eymard
- APHP, Centre de Référence de pathologie neuromusculaire Paris-Est, Myology Institute, Neurology Department, Pitié-Salpêtrière Hospital, Paris, France
- Pierre et Marie Curie-Paris 6 University, Paris, France
| | - Denis Duboc
- APHP, Cochin Hospital, Cardiology Department, Paris-Descartes, Sorbonne Paris Cité University, Paris, France
- APHP, Centre de Référence de pathologie neuromusculaire Paris-Est, Myology Institute, Neurology Department, Pitié-Salpêtrière Hospital, Paris, France
- Inserm, UMRS 974, Paris, France
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Lima L, Sinaimeri B, Sacomoto G, Lopez-Maestre H, Marchet C, Miele V, Sagot MF, Lacroix V. Playing hide and seek with repeats in local and global de novo transcriptome assembly of short RNA-seq reads. Algorithms Mol Biol 2017; 12:2. [PMID: 28250805 PMCID: PMC5322684 DOI: 10.1186/s13015-017-0091-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2016] [Accepted: 01/27/2017] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND The main challenge in de novo genome assembly of DNA-seq data is certainly to deal with repeats that are longer than the reads. In de novo transcriptome assembly of RNA-seq reads, on the other hand, this problem has been underestimated so far. Even though we have fewer and shorter repeated sequences in transcriptomics, they do create ambiguities and confuse assemblers if not addressed properly. Most transcriptome assemblers of short reads are based on de Bruijn graphs (DBG) and have no clear and explicit model for repeats in RNA-seq data, relying instead on heuristics to deal with them. RESULTS The results of this work are threefold. First, we introduce a formal model for representing high copy-number and low-divergence repeats in RNA-seq data and exploit its properties to infer a combinatorial characteristic of repeat-associated subgraphs. We show that the problem of identifying such subgraphs in a DBG is NP-complete. Second, we show that in the specific case of local assembly of alternative splicing (AS) events, we can implicitly avoid such subgraphs, and we present an efficient algorithm to enumerate AS events that are not included in repeats. Using simulated data, we show that this strategy is significantly more sensitive and precise than the previous version of KisSplice (Sacomoto et al. in WABI, pp 99-111, 1), Trinity (Grabherr et al. in Nat Biotechnol 29(7):644-652, 2), and Oases (Schulz et al. in Bioinformatics 28(8):1086-1092, 3), for the specific task of calling AS events. Third, we turn our focus to full-length transcriptome assembly, and we show that exploring the topology of DBGs can improve de novo transcriptome evaluation methods. Based on the observation that repeats create complicated regions in a DBG, and when assemblers try to traverse these regions, they can infer erroneous transcripts, we propose a measure to flag transcripts traversing such troublesome regions, thereby giving a confidence level for each transcript. The originality of our work when compared to other transcriptome evaluation methods is that we use only the topology of the DBG, and not read nor coverage information. We show that our simple method gives better results than Rsem-Eval (Li et al. in Genome Biol 15(12):553, 4) and TransRate (Smith-Unna et al. in Genome Res 26(8):1134-1144, 5) on both real and simulated datasets for detecting chimeras, and therefore is able to capture assembly errors missed by these methods.
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Affiliation(s)
- Leandro Lima
- Inria Grenoble, 655, Avenue de l’Europe, 38334 Montbonnot, France
- CNRS, UMR5558, Université Claude Bernard Lyon 1, 43, Boulevard du 11 Novembre 1918, 69622 Villeurbanne, France
| | - Blerina Sinaimeri
- Inria Grenoble, 655, Avenue de l’Europe, 38334 Montbonnot, France
- CNRS, UMR5558, Université Claude Bernard Lyon 1, 43, Boulevard du 11 Novembre 1918, 69622 Villeurbanne, France
| | - Gustavo Sacomoto
- Inria Grenoble, 655, Avenue de l’Europe, 38334 Montbonnot, France
- CNRS, UMR5558, Université Claude Bernard Lyon 1, 43, Boulevard du 11 Novembre 1918, 69622 Villeurbanne, France
| | - Helene Lopez-Maestre
- Inria Grenoble, 655, Avenue de l’Europe, 38334 Montbonnot, France
- CNRS, UMR5558, Université Claude Bernard Lyon 1, 43, Boulevard du 11 Novembre 1918, 69622 Villeurbanne, France
| | - Camille Marchet
- IRISA Inria Rennes Bretagne Atlantique; GenScale Team, Université Rennes 1, 263, Avenue Général Leclerc, 35042 Rennes, France
| | - Vincent Miele
- CNRS, UMR5558, Université Claude Bernard Lyon 1, 43, Boulevard du 11 Novembre 1918, 69622 Villeurbanne, France
| | - Marie-France Sagot
- Inria Grenoble, 655, Avenue de l’Europe, 38334 Montbonnot, France
- CNRS, UMR5558, Université Claude Bernard Lyon 1, 43, Boulevard du 11 Novembre 1918, 69622 Villeurbanne, France
| | - Vincent Lacroix
- Inria Grenoble, 655, Avenue de l’Europe, 38334 Montbonnot, France
- CNRS, UMR5558, Université Claude Bernard Lyon 1, 43, Boulevard du 11 Novembre 1918, 69622 Villeurbanne, France
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Hooker JM, Strebl MG, Schroeder FA, Wey HY, Ambardekar AV, McKinsey TA, Schoenberger M. Imaging cardiac SCN5A using the novel F-18 radiotracer radiocaine. Sci Rep 2017; 7:42136. [PMID: 28205593 PMCID: PMC5311962 DOI: 10.1038/srep42136] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Accepted: 01/08/2017] [Indexed: 12/19/2022] Open
Abstract
The key function of the heart, a well-orchestrated series of contractions, is controlled by cardiac action potentials. These action potentials are initiated and propagated by a single isoform of voltage gated sodium channels - SCN5A. However, linking changes in SCN5A expression levels to human disease in vivo has not yet been possible. Radiocaine, an F-18 radiotracer for positron emission tomography (PET), is the first SCN5A imaging agent in the heart. Explants from healthy and failing human hearts were compared using radiocaine autoradiography to determine that the failing heart has ~30% lower SCN5A levels - the first evidence of changes in SCN5A expression in humans as a function of disease. Paving the way for translational imaging, radiocaine proved to exhibit high in vivo specific binding to the myocardium of non-human primates. We envision that SCN5A measurements using PET imaging may serve as a novel diagnostic tool to stratify arrhythmia risk and assess for progression of heart failure in patients with a broad spectrum of cardiovascular diseases.
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Affiliation(s)
- Jacob M Hooker
- Harvard Medical School, Massachusetts General Hospital, Martinos Center for Biomedical Imaging, 149 13th Street, 02129 Charlestown, MA, USA
| | - Martin G Strebl
- Harvard Medical School, Massachusetts General Hospital, Martinos Center for Biomedical Imaging, 149 13th Street, 02129 Charlestown, MA, USA
| | - Frederick A Schroeder
- Harvard Medical School, Massachusetts General Hospital, Martinos Center for Biomedical Imaging, 149 13th Street, 02129 Charlestown, MA, USA
| | - Hsiao-Ying Wey
- Harvard Medical School, Massachusetts General Hospital, Martinos Center for Biomedical Imaging, 149 13th Street, 02129 Charlestown, MA, USA
| | - Amrut V Ambardekar
- Department of Medicine, Division of Cardiology and Consortium for Fibrosis Research and Translation, University of Colorado - Anschutz Medical Campus, Aurora, CO, USA
| | - Timothy A McKinsey
- Department of Medicine, Division of Cardiology and Consortium for Fibrosis Research and Translation, University of Colorado - Anschutz Medical Campus, Aurora, CO, USA
| | - Matthias Schoenberger
- Harvard Medical School, Massachusetts General Hospital, Martinos Center for Biomedical Imaging, 149 13th Street, 02129 Charlestown, MA, USA
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Hartley SW, Mullikin JC, Klein DC, Park M, Coon SL. Alternative Isoform Analysis of Ttc8 Expression in the Rat Pineal Gland Using a Multi-Platform Sequencing Approach Reveals Neural Regulation. PLoS One 2016; 11:e0163590. [PMID: 27684375 PMCID: PMC5042479 DOI: 10.1371/journal.pone.0163590] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Accepted: 09/12/2016] [Indexed: 01/23/2023] Open
Abstract
Alternative isoform regulation (AIR) vastly increases transcriptome diversity and plays an important role in numerous biological processes and pathologies. However, the detection and analysis of isoform-level differential regulation is difficult, particularly in the face of complex and incompletely-annotated transcriptomes. Here we have used Illumina short-read/high-throughput RNA-Seq to identify 55 genes that exhibit neurally-regulated AIR in the pineal gland, and then used two other complementary experimental platforms to further study and characterize the Ttc8 gene, which is involved in Bardet-Biedl syndrome and non-syndromic retinitis pigmentosa. Use of the JunctionSeq analysis tool led to the detection of several novel exons and splice junctions in this gene, including two novel alternative transcription start sites which were found to display disproportionately strong neurally-regulated differential expression in several independent experiments. These high-throughput sequencing results were validated and augmented via targeted qPCR and long-read Pacific Biosciences SMRT sequencing. We confirmed the existence of numerous novel splice junctions and the selective upregulation of the two novel start sites. In addition, we identified more than 20 novel isoforms of the Ttc8 gene that are co-expressed in this tissue. By using information from multiple independent platforms we not only greatly reduce the risk of errors, biases, and artifacts influencing our results, we also are able to characterize the regulation and splicing of the Ttc8 gene more deeply and more precisely than would be possible via any single platform. The hybrid method outlined here represents a powerful strategy in the study of the transcriptome.
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Affiliation(s)
- Stephen W. Hartley
- Comparative Genomics Analysis Unit, Cancer Genetics and Comparative Genomics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland, 20892, United States of America
- * E-mail:
| | - James C. Mullikin
- Comparative Genomics Analysis Unit, Cancer Genetics and Comparative Genomics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland, 20892, United States of America
| | - David C. Klein
- Section on Neuroendocrinology, Program in Developmental Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, 20892, United States of America
| | - Morgan Park
- National Institutes of Health Intramural Sequencing Center, National Human Genome Research Institute, National Institutes of Health, Rockville, Maryland, 20852, United States of America
| | - NISC Comparative Sequencing Program
- National Institutes of Health Intramural Sequencing Center, National Human Genome Research Institute, National Institutes of Health, Rockville, Maryland, 20852, United States of America
| | - Steven L. Coon
- Section on Neuroendocrinology, Program in Developmental Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, 20892, United States of America
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135
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Juang JMJ, Horie M. Genetics of Brugada syndrome. J Arrhythm 2016; 32:418-425. [PMID: 27761167 PMCID: PMC5063259 DOI: 10.1016/j.joa.2016.07.012] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Revised: 05/03/2016] [Accepted: 07/06/2016] [Indexed: 12/19/2022] Open
Abstract
In 1992, the Brugada syndrome (BrS) was recognized as a disease responsible for sudden cardiac death, characterized by a right bundle-branch block with ST segment elevation in the leads V1 and V2. This syndrome is highly associated with sudden cardiac death, especially in young males. BrS is currently diagnosed in patients with ST-segment elevation showing type 1 morphology ≥ 2 mm in ≥1 leads among the right precordial leads V1 or V2 positioned in the 2nd, 3rd, or 4th intercostal space, and occurring either spontaneously or after a provocative drug test by the intravenous administration of Class I antiarrhythmic drugs. With accumulated findings, the BrS inheritance model is believed to be an autosomal dominant inheritable model with incomplete penetrance, although most patients with BrS were sporadic cases. SCN5A, which was identified as the first BrS-associated gene in 1998, has emerged as the most common gene associated with BrS, and more than 10 BrS-associated genes have been identified thereafter. Mutation-specific genetic testing is recommended for the family members and appropriate relatives following the identification of BrS-causative mutations in an index patient. In addition, comprehensive or BrS1 (SCN5A) targeted genetic testing could be useful for patients in whom a cardiologist has established a clinical index of suspicion for BrS based on the patient׳s clinical history, family history, and the expressed electrocardiographic (resting 12-lead ECGs and/or provocative drug challenge testing) phenotype. Over the past 20 years, extensive research in this field has allowed better understanding of the pathophysiology, genetic background, and management of BrS even though controversies still exist. In this review article, a background of genetics, the genetic background of BrS, the genotype and phenotype relationship, the role of genetic screening in clinical practice, and the interpretation of the identified genetic variants have been addressed based on this understanding.
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Affiliation(s)
- Jyh-Ming Jimmy Juang
- Cardiovascular Center and Division of Cardiology, Department of Internal Medicine, National Taiwan University Hospital and National Taiwan University College of Medicine, Taipei, Taiwan
| | - Minoru Horie
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science, Otsu, Japan
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