1
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Engquist EN, Greco A, Joosten LAB, van Engelen BGM, Zammit PS, Banerji CRS. FSHD muscle shows perturbation in fibroadipogenic progenitor cells, mitochondrial function and alternative splicing independently of inflammation. Hum Mol Genet 2024; 33:182-197. [PMID: 37856562 PMCID: PMC10772042 DOI: 10.1093/hmg/ddad175] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Revised: 09/25/2023] [Accepted: 10/10/2023] [Indexed: 10/21/2023] Open
Abstract
Facioscapulohumeral muscular dystrophy (FSHD) is a prevalent, incurable myopathy. FSHD is highly heterogeneous, with patients following a variety of clinical trajectories, complicating clinical trials. Skeletal muscle in FSHD undergoes fibrosis and fatty replacement that can be accelerated by inflammation, adding to heterogeneity. Well controlled molecular studies are thus essential to both categorize FSHD patients into distinct subtypes and understand pathomechanisms. Here, we further analyzed RNA-sequencing data from 24 FSHD patients, each of whom donated a biopsy from both a non-inflamed (TIRM-) and inflamed (TIRM+) muscle, and 15 FSHD patients who donated peripheral blood mononucleated cells (PBMCs), alongside non-affected control individuals. Differential gene expression analysis identified suppression of mitochondrial biogenesis and up-regulation of fibroadipogenic progenitor (FAP) gene expression in FSHD muscle, which was particularly marked on inflamed samples. PBMCs demonstrated suppression of antigen presentation in FSHD. Gene expression deconvolution revealed FAP expansion as a consistent feature of FSHD muscle, via meta-analysis of 7 independent transcriptomic datasets. Clustering of muscle biopsies separated patients in an unbiased manner into clinically mild and severe subtypes, independently of known disease modifiers (age, sex, D4Z4 repeat length). Lastly, the first genome-wide analysis of alternative splicing in FSHD muscle revealed perturbation of autophagy, BMP2 and HMGB1 signalling. Overall, our findings reveal molecular subtypes of FSHD with clinical relevance and identify novel pathomechanisms for this highly heterogeneous condition.
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Affiliation(s)
- Elise N Engquist
- Randall Centre for Cell and Molecular Biophysics, King's College London, New Hunt's House, Guy's Campus, London SE1 1UL, United Kingdom
| | - Anna Greco
- Department of Neurology, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, 6525 GA, The Netherlands
- Department of Internal Medicine, Radboud Institute of Molecular Life Sciences (RIMLS) and Radboud Center of Infectious Diseases (RCI), Radboud University Medical Center, Geert Grooteplein Zuid 10, Nijmegen 6525 GA, The Netherlands
| | - Leo A B Joosten
- Department of Internal Medicine, Radboud Institute of Molecular Life Sciences (RIMLS) and Radboud Center of Infectious Diseases (RCI), Radboud University Medical Center, Geert Grooteplein Zuid 10, Nijmegen 6525 GA, The Netherlands
- Department of Medical Genetics, Iuliu Hatieganu University of Medicine and Pharmacy, 400012, Cluj-Napoca, Romania
| | - Baziel G M van Engelen
- Department of Neurology, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, 6525 GA, The Netherlands
| | - Peter S Zammit
- Randall Centre for Cell and Molecular Biophysics, King's College London, New Hunt's House, Guy's Campus, London SE1 1UL, United Kingdom
| | - Christopher R S Banerji
- Randall Centre for Cell and Molecular Biophysics, King's College London, New Hunt's House, Guy's Campus, London SE1 1UL, United Kingdom
- The Alan Turing Institute, The British Library, 96 Euston Road, London NW1 2DB, United Kingdom
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2
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Alexander MS, Hightower RM, Reid AL, Bennett AH, Iyer L, Slonim DK, Saha M, Kawahara G, Kunkel LM, Kopin AS, Gupta VA, Kang PB, Draper I. hnRNP L is essential for myogenic differentiation and modulates myotonic dystrophy pathologies. Muscle Nerve 2021; 63:928-940. [PMID: 33651408 DOI: 10.1002/mus.27216] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Revised: 02/25/2021] [Accepted: 02/28/2021] [Indexed: 12/12/2022]
Abstract
INTRODUCTION RNA-binding proteins (RBPs) play an important role in skeletal muscle development and disease by regulating RNA splicing. In myotonic dystrophy type 1 (DM1), the RBP MBNL1 (muscleblind-like) is sequestered by toxic CUG repeats, leading to missplicing of MBNL1 targets. Mounting evidence from the literature has implicated other factors in the pathogenesis of DM1. Herein we sought to evaluate the functional role of the splicing factor hnRNP L in normal and DM1 muscle cells. METHODS Co-immunoprecipitation assays using hnRNPL and MBNL1 expression constructs and splicing profiling in normal and DM1 muscle cell lines were performed. Zebrafish morpholinos targeting hnrpl and hnrnpl2 were injected into one-cell zebrafish for developmental and muscle analysis. In human myoblasts downregulation of hnRNP L was achieved with shRNAi. Ascochlorin administration to DM1 myoblasts was performed and expression of the CUG repeats, DM1 splicing biomarkers, and hnRNP L expression levels were evaluated. RESULTS Using DM1 patient myoblast cell lines we observed the formation of abnormal hnRNP L nuclear foci within and outside the expanded CUG repeats, suggesting a role for this factor in DM1 pathology. We showed that the antiviral and antitumorigenic isoprenoid compound ascochlorin increased MBNL1 and hnRNP L expression levels. Drug treatment of DM1 muscle cells with ascochlorin partially rescued missplicing of established early biomarkers of DM1 and improved the defective myotube formation displayed by DM1 muscle cells. DISCUSSION Together, these studies revealed that hnRNP L can modulate DM1 pathologies and is a potential therapeutic target.
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Affiliation(s)
- Matthew S Alexander
- Division of Neurology, Department of Pediatrics, University of Alabama at Birmingham and Children's of Alabama, Birmingham, Alabama, USA.,Center for Exercise Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA.,Department of Genetics, University of Alabama at Birmingham, Birmingham, Alabama, USA.,Civitan International Research Center, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Rylie M Hightower
- Division of Neurology, Department of Pediatrics, University of Alabama at Birmingham and Children's of Alabama, Birmingham, Alabama, USA.,Center for Exercise Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Andrea L Reid
- Division of Neurology, Department of Pediatrics, University of Alabama at Birmingham and Children's of Alabama, Birmingham, Alabama, USA
| | - Alexis H Bennett
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - Lakshmanan Iyer
- Department of Neuroscience, Tufts University, Boston, Massachusetts, USA
| | - Donna K Slonim
- Department of Computer Science, Tufts University, Medford, Massachusetts, USA
| | - Madhurima Saha
- Division of Pediatric Neurology, Department of Pediatrics, University of Florida College of Medicine, Gainesville, Florida, USA
| | - Genri Kawahara
- Department of Pathophysiology, Tokyo Medical University, Tokyo, Japan
| | - Louis M Kunkel
- Division of Genetics and Genomics, Boston Children's Hospital, Boston, Massachusetts, USA.,Department of Genetics, Harvard Medical School, Boston, Massachusetts, USA.,Harvard Stem Cell Institute, Cambridge, Massachusetts, USA.,The Manton Center for Orphan Disease Research, Boston Children's Hospital, Boston, Massachusetts, USA
| | - Alan S Kopin
- Department of Medicine, Molecular Cardiology Research Institute, Tufts Medical Center, Boston, Massachusetts, USA
| | - Vandana A Gupta
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - Peter B Kang
- Division of Pediatric Neurology, Department of Pediatrics, University of Florida College of Medicine, Gainesville, Florida, USA.,Department of Molecular Genetics and Microbiology, University of Florida College of Medicine, Gainesville, Florida, USA.,Department of Neurology, University of Florida College of Medicine, Gainesville, Florida, USA.,Genetics Institute and Myology Institute, University of Florida, Gainesville, Florida, USA.,Paul and Sheila Wellstone Muscular Dystrophy Center, University of Minnesota Medical School, Minneapolis, Minnesota, USA.,Neurology Department, University of Minnesota Medical School, Minneapolis, Minnesota, USA
| | - Isabelle Draper
- Department of Medicine, Molecular Cardiology Research Institute, Tufts Medical Center, Boston, Massachusetts, USA
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3
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Mapping drug-target interactions and synergy in multi-molecular therapeutics for pressure-overload cardiac hypertrophy. NPJ Syst Biol Appl 2021; 7:11. [PMID: 33589646 PMCID: PMC7884732 DOI: 10.1038/s41540-021-00171-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Accepted: 01/13/2021] [Indexed: 01/31/2023] Open
Abstract
Advancements in systems biology have resulted in the development of network pharmacology, leading to a paradigm shift from "one-target, one-drug" to "target-network, multi-component therapeutics". We employ a chimeric approach involving in-vivo assays, gene expression analysis, cheminformatics, and network biology to deduce the regulatory actions of a multi-constituent Ayurvedic concoction, Amalaki Rasayana (AR) in animal models for its effect in pressure-overload cardiac hypertrophy. The proteomics analysis of in-vivo assays for Aorta Constricted and Biologically Aged rat models identify proteins expressed under each condition. Network analysis mapping protein-protein interactions and synergistic actions of AR using multi-component networks reveal drug targets such as ACADM, COX4I1, COX6B1, HBB, MYH14, and SLC25A4, as potential pharmacological co-targets for cardiac hypertrophy. Further, five out of eighteen AR constituents potentially target these proteins. We propose a distinct prospective strategy for the discovery of network pharmacological therapies and repositioning of existing drug molecules for treating pressure-overload cardiac hypertrophy.
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Voss DM, Sloan A, Spina R, Ames HM, Bar EE. The Alternative Splicing Factor, MBNL1, Inhibits Glioblastoma Tumor Initiation and Progression by Reducing Hypoxia-Induced Stemness. Cancer Res 2020; 80:4681-4692. [PMID: 32928918 DOI: 10.1158/0008-5472.can-20-1233] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Revised: 06/23/2020] [Accepted: 09/09/2020] [Indexed: 12/31/2022]
Abstract
Muscleblind-like proteins (MBNL) belong to a family of tissue-specific regulators of RNA metabolism that control premessenger RNA splicing. Inactivation of MBNL causes an adult-to-fetal alternative splicing transition, resulting in the development of myotonic dystrophy. We have previously shown that the aggressive brain cancer, glioblastoma (GBM), maintains stem-like features (glioma stem cell, GSC) through hypoxia-induced responses. Accordingly, we hypothesize here that hypoxia-induced responses in GBM might also include MBNL-based alternative splicing to promote tumor progression. When cultured in hypoxia condition, GSCs rapidly exported muscleblind-like-1 (MBNL1) out of the nucleus, resulting in significant inhibition of MBNL1 activity. Notably, hypoxia-regulated inhibition of MBNL1 also resulted in evidence of adult-to-fetal alternative splicing transitions. Forced expression of a constitutively active isoform of MBNL1 inhibited GSC self-renewal and tumor initiation in orthotopic transplantation models. Induced expression of MBNL1 in established orthotopic tumors dramatically inhibited tumor progression, resulting in significantly prolonged survival. This study reveals that MBNL1 plays an essential role in GBM stemness and tumor progression, where hypoxic responses within the tumor inhibit MBNL1 activity, promoting stem-like phenotypes and tumor growth. Reversing these effects on MBNL1 may therefore, yield potent tumor suppressor activities, uncovering new therapeutic opportunities to counter this disease. SIGNIFICANCE: This study describes an unexpected mechanism by which RNA-binding protein, MBNL1, activity is inhibited in hypoxia by a simple isoform switch to regulate glioma stem cell self-renewal, tumorigenicity, and progression.
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Affiliation(s)
- Dillon M Voss
- Department of Neurological Surgery, Case Western Reserve University School of Medicine, Cleveland, Ohio
| | - Anthony Sloan
- Department of Neurological Surgery, Case Western Reserve University School of Medicine, Cleveland, Ohio
| | - Raffaella Spina
- Department of Pathology, University of Maryland School of Medicine, Baltimore, Maryland.,Department of Neurosurgery, University of Maryland School of Medicine, Baltimore, Maryland.,Marlene and Stewart Greenebaum Comprehensive Cancer Center, University of Maryland School of Medicine, Baltimore, Maryland
| | - Heather M Ames
- Department of Pathology, University of Maryland School of Medicine, Baltimore, Maryland.,Marlene and Stewart Greenebaum Comprehensive Cancer Center, University of Maryland School of Medicine, Baltimore, Maryland
| | - Eli E Bar
- Department of Pathology, University of Maryland School of Medicine, Baltimore, Maryland. .,Department of Neurosurgery, University of Maryland School of Medicine, Baltimore, Maryland.,Marlene and Stewart Greenebaum Comprehensive Cancer Center, University of Maryland School of Medicine, Baltimore, Maryland
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5
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Abstract
Myosins constitute a superfamily of actin-based molecular motor proteins that mediates a variety of cellular activities including muscle contraction, cell migration, intracellular transport, the formation of membrane projections, cell adhesion, and cell signaling. The 12 myosin classes that are expressed in humans share sequence similarities especially in the N-terminal motor domain; however, their enzymatic activities, regulation, ability to dimerize, binding partners, and cellular functions differ. It is becoming increasingly apparent that defects in myosins are associated with diseases including cardiomyopathies, colitis, glomerulosclerosis, neurological defects, cancer, blindness, and deafness. Here, we review the current state of knowledge regarding myosins and disease.
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6
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Nikonova E, Kao SY, Ravichandran K, Wittner A, Spletter ML. Conserved functions of RNA-binding proteins in muscle. Int J Biochem Cell Biol 2019; 110:29-49. [PMID: 30818081 DOI: 10.1016/j.biocel.2019.02.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2018] [Revised: 02/21/2019] [Accepted: 02/23/2019] [Indexed: 12/13/2022]
Abstract
Animals require different types of muscle for survival, for example for circulation, motility, reproduction and digestion. Much emphasis in the muscle field has been placed on understanding how transcriptional regulation generates diverse types of muscle during development. Recent work indicates that alternative splicing and RNA regulation are as critical to muscle development, and altered function of RNA-binding proteins causes muscle disease. Although hundreds of genes predicted to bind RNA are expressed in muscles, many fewer have been functionally characterized. We present a cross-species view summarizing what is known about RNA-binding protein function in muscle, from worms and flies to zebrafish, mice and humans. In particular, we focus on alternative splicing regulated by the CELF, MBNL and RBFOX families of proteins. We discuss the systemic nature of diseases associated with loss of RNA-binding proteins in muscle, focusing on mis-regulation of CELF and MBNL in myotonic dystrophy. These examples illustrate the conservation of RNA-binding protein function and the marked utility of genetic model systems in understanding mechanisms of RNA regulation.
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Affiliation(s)
- Elena Nikonova
- Biomedical Center, Department of Physiological Chemistry, Ludwig-Maximilians-University München, Großhaderner Str. 9, 82152, Martinsried-Planegg, Germany
| | - Shao-Yen Kao
- Biomedical Center, Department of Physiological Chemistry, Ludwig-Maximilians-University München, Großhaderner Str. 9, 82152, Martinsried-Planegg, Germany
| | - Keshika Ravichandran
- Biomedical Center, Department of Physiological Chemistry, Ludwig-Maximilians-University München, Großhaderner Str. 9, 82152, Martinsried-Planegg, Germany
| | - Anja Wittner
- Biomedical Center, Department of Physiological Chemistry, Ludwig-Maximilians-University München, Großhaderner Str. 9, 82152, Martinsried-Planegg, Germany
| | - Maria L Spletter
- Biomedical Center, Department of Physiological Chemistry, Ludwig-Maximilians-University München, Großhaderner Str. 9, 82152, Martinsried-Planegg, Germany; Center for Integrated Protein Science Munich (CIPSM) at the Department of Chemistry, Ludwig-Maximilians-Universität München, Munich, Germany.
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7
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Picchio L, Legagneux V, Deschamps S, Renaud Y, Chauveau S, Paillard L, Jagla K. Bruno-3 regulates sarcomere component expression and contributes to muscle phenotypes of myotonic dystrophy type 1. Dis Model Mech 2018; 11:dmm.031849. [PMID: 29716962 PMCID: PMC5992612 DOI: 10.1242/dmm.031849] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Accepted: 04/18/2018] [Indexed: 01/22/2023] Open
Abstract
Steinert disease, or myotonic dystrophy type 1 (DM1), is a multisystemic disorder caused by toxic noncoding CUG repeat transcripts, leading to altered levels of two RNA binding factors, MBNL1 and CELF1. The contribution of CELF1 to DM1 phenotypes is controversial. Here, we show that the Drosophila CELF1 family member, Bru-3, contributes to pathogenic muscle defects observed in a Drosophila model of DM1. Bru-3 displays predominantly cytoplasmic expression in muscles and its muscle-specific overexpression causes a range of phenotypes also observed in the fly DM1 model, including affected motility, fiber splitting, reduced myofiber length and altered myoblast fusion. Interestingly, comparative genome-wide transcriptomic analyses revealed that Bru-3 negatively regulates levels of mRNAs encoding a set of sarcomere components, including Actn transcripts. Conversely, it acts as a positive regulator of Actn translation. As CELF1 displays predominantly cytoplasmic expression in differentiating C2C12 myotubes and binds to Actn mRNA, we hypothesize that it might exert analogous functions in vertebrate muscles. Altogether, we propose that cytoplasmic Bru-3 contributes to DM1 pathogenesis in a Drosophila model by regulating sarcomeric transcripts and protein levels.
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Affiliation(s)
- Lucie Picchio
- GReD (Genetics, Reproduction and Development Laboratory), INSERM 1103, CNRS 6293, University of Clermont Auvergne, 28 Place Henri Dunant, 63000 Clermont-Ferrand, France
| | - Vincent Legagneux
- IGDR (Institut de Génétique et Développement de Rennes), UMR 6290 CNRS, Université de Rennes, 2 Avenue Léon Bernard, 35000 Rennes, France.,Inserm UMR1085 IRSET, Université de Rennes 1, 35000 Rennes, France.,CNRS-Université de Rennes1-INRIA, UMR6074 IRISA, 35000 Rennes, France
| | - Stephane Deschamps
- IGDR (Institut de Génétique et Développement de Rennes), UMR 6290 CNRS, Université de Rennes, 2 Avenue Léon Bernard, 35000 Rennes, France
| | - Yoan Renaud
- GReD (Genetics, Reproduction and Development Laboratory), INSERM 1103, CNRS 6293, University of Clermont Auvergne, 28 Place Henri Dunant, 63000 Clermont-Ferrand, France
| | - Sabine Chauveau
- GReD (Genetics, Reproduction and Development Laboratory), INSERM 1103, CNRS 6293, University of Clermont Auvergne, 28 Place Henri Dunant, 63000 Clermont-Ferrand, France
| | - Luc Paillard
- IGDR (Institut de Génétique et Développement de Rennes), UMR 6290 CNRS, Université de Rennes, 2 Avenue Léon Bernard, 35000 Rennes, France
| | - Krzysztof Jagla
- GReD (Genetics, Reproduction and Development Laboratory), INSERM 1103, CNRS 6293, University of Clermont Auvergne, 28 Place Henri Dunant, 63000 Clermont-Ferrand, France
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8
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van Vliet J, Tieleman AA, van Engelen BG, Bassez G, Servais L, Béhin A, Stojkovic T, Meulstee J, Engel JA, Lamas G, Eymard B, Verhagen WI, Mamelle E. Hearing impairment in patients with myotonic dystrophy type 2. Neurology 2018; 90:e615-e622. [DOI: 10.1212/wnl.0000000000004963] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2017] [Accepted: 11/09/2017] [Indexed: 11/15/2022] Open
Abstract
ObjectiveTo systematically assess auditory characteristics of a large cohort of patients with genetically confirmed myotonic dystrophy type 2 (DM2).MethodsPatients with DM2 were included prospectively in an international cross-sectional study. A structured interview about hearing symptoms was held. Thereafter, standardized otologic examination, pure tone audiometry (PTA; 0.25, 0.5, 1, 2, 4, and 8 kHz), speech audiometry, tympanometry, acoustic middle ear muscle reflexes, and brainstem auditory evoked potentials (BAEP) were performed. The ISO 7029 standard was used to compare the PTA results with established hearing thresholds of the general population according to sex and age.ResultsThirty-one Dutch and 25 French patients with DM2 (61% female) were included with a mean age of 57 years (range 31–78). The median hearing threshold of the DM2 cohort was higher for all measured frequencies, compared to the 50th percentile of normal (p < 0.001). Hearing impairment was mild in 39%, moderate in 21%, and severe in 2% of patients with DM2. The absence of an air–bone gap with PTA, concordant results of speech audiometry with PTA, and normal findings of BAEP suggest that the sensorineural hearing impairment is located in the cochlea. A significant correlation was found between hearing impairment and age, even when corrected for presbycusis.ConclusionsCochlear sensorineural hearing impairment is a frequent symptom in patients with DM2, suggesting an early presbycusis. Therefore, we recommend informing about hearing impairment and readily performing audiometry when hearing impairment is suspected in order to propose early hearing rehabilitation with hearing aids when indicated.
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Dose-Dependent Regulation of Alternative Splicing by MBNL Proteins Reveals Biomarkers for Myotonic Dystrophy. PLoS Genet 2016; 12:e1006316. [PMID: 27681373 PMCID: PMC5082313 DOI: 10.1371/journal.pgen.1006316] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Accepted: 08/23/2016] [Indexed: 01/23/2023] Open
Abstract
Alternative splicing is a regulated process that results in expression of
specific mRNA and protein isoforms. Alternative splicing factors determine the
relative abundance of each isoform. Here we focus on MBNL1, a splicing factor
misregulated in the disease myotonic dystrophy. By altering the concentration of
MBNL1 in cells across a broad dynamic range, we show that different splicing
events require different amounts of MBNL1 for half-maximal response, and respond
more or less steeply to MBNL1. Motifs around MBNL1 exon 5 were studied to assess
how cis-elements mediate the MBNL1 dose-dependent splicing
response. A framework was developed to estimate MBNL concentration using
splicing responses alone, validated in the cell-based model, and applied to
myotonic dystrophy patient muscle. Using this framework, we evaluated the
ability of individual and combinations of splicing events to predict functional
MBNL concentration in human biopsies, as well as their performance as biomarkers
to assay mild, moderate, and severe cases of DM. Our studies provide insight into the mechanisms of myotonic dystrophy, the most
common adult form of muscular dystrophy. In this disease, a family of RNA
binding proteins is sequestered by toxic RNA, which leads to mis-regulation and
disease symptoms. We have created a cellular model with one of these family
members to study how these RNA binding proteins function in the absence of the
toxic RNA. In parallel, we analyzed transcriptomic data from over 50 individuals
(44 affected by myotonic dystrophy) with a range of disease severity. The
results from the transcriptomic data provide a rational approach to select
biomarkers for clinical research and therapeutic trials.
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Betapudi V. Life without double-headed non-muscle myosin II motor proteins. Front Chem 2014; 2:45. [PMID: 25072053 PMCID: PMC4083560 DOI: 10.3389/fchem.2014.00045] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2014] [Accepted: 06/19/2014] [Indexed: 11/20/2022] Open
Abstract
Non-muscle myosin II motor proteins (myosin IIA, myosin IIB, and myosin IIC) belong to a class of molecular motor proteins that are known to transduce cellular free-energy into biological work more efficiently than man-made combustion engines. Nature has given a single myosin II motor protein for lower eukaryotes and multiple for mammals but none for plants in order to provide impetus for their life. These specialized nanomachines drive cellular activities necessary for embryogenesis, organogenesis, and immunity. However, these multifunctional myosin II motor proteins are believed to go awry due to unknown reasons and contribute for the onset and progression of many autosomal-dominant disorders, cataract, deafness, infertility, cancer, kidney, neuronal, and inflammatory diseases. Many pathogens like HIV, Dengue, hepatitis C, and Lymphoma viruses as well as Salmonella and Mycobacteria are now known to take hostage of these dedicated myosin II motor proteins for their efficient pathogenesis. Even after four decades since their discovery, we still have a limited knowledge of how these motor proteins drive cell migration and cytokinesis. We need to enrich our current knowledge on these fundamental cellular processes and develop novel therapeutic strategies to fix mutated myosin II motor proteins in pathological conditions. This is the time to think how to relieve the hijacked myosins from pathogens in order to provide a renewed impetus for patients' life. Understanding how to steer these molecular motors in proliferating and differentiating stem cells will improve stem cell based-therapeutics development. Given the plethora of cellular activities non-muscle myosin motor proteins are involved in, their importance is apparent for human life.
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Affiliation(s)
- Venkaiah Betapudi
- Department of Cellular and Molecular Medicine, Lerner Research Institute, Cleveland Clinic Cleveland, OH, USA ; Department of Physiology and Biophysics, Case Western Reserve University Cleveland, OH, USA
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11
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Yamashita Y, Matsuura T, Kurosaki T, Amakusa Y, Kinoshita M, Ibi T, Sahashi K, Ohno K. LDB3 splicing abnormalities are specific to skeletal muscles of patients with myotonic dystrophy type 1 and alter its PKC binding affinity. Neurobiol Dis 2014; 69:200-5. [PMID: 24878509 DOI: 10.1016/j.nbd.2014.05.026] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2014] [Revised: 05/06/2014] [Accepted: 05/19/2014] [Indexed: 01/20/2023] Open
Abstract
Myotonic dystrophy type 1 (DM1) is caused by transcription of CUG repeat RNA, which causes sequestration of muscleblind-like 1 (MBNL1) and upregulation of CUG triplet repeat RNA-binding protein (CUG-BP1). In DM1, dysregulation of these proteins contributes to many aberrant splicing events, causing various symptoms of the disorder. Here, we demonstrate the occurrence of aberrant splicing of LIM domain binding 3 (LDB3) exon 11 in DM1 skeletal muscle. Exon array surveys, RT-PCR, and western blotting studies demonstrated that exon 11 inclusion was DM1 specific and could be reproduced by transfection of a minigene containing the CTG repeat expansion. Moreover, we found that the LDB3 exon 11-positive isoform had reduced affinity for PKC compared to the exon 11-negative isoform. Since PKC exhibits hyperactivation in DM1 and stabilizes CUG-BP1 by phosphorylation, aberrant splicing of LDB3 may contribute to CUG-BP1 upregulation through changes in its affinity for PKC.
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Affiliation(s)
- Yoshihiro Yamashita
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Tohru Matsuura
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya, Japan; Division of Neurology, Department of Medicine, Jichi Medical University, Shomotsuke, Japan.
| | - Tatsuaki Kurosaki
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Yoshinobu Amakusa
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Masanobu Kinoshita
- Department of Frontier Health Sciences, Graduate School of Human Health Sciences, Tokyo Metropolitan University, Tokyo, Japan
| | - Tohru Ibi
- Department of Neurology, Aichi Medical University School of Medicine, Aichi, Japan
| | - Ko Sahashi
- Department of Neurology, Aichi Medical University School of Medicine, Aichi, Japan
| | - Kinji Ohno
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya, Japan
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12
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MBNL1 and RBFOX2 cooperate to establish a splicing programme involved in pluripotent stem cell differentiation. Nat Commun 2014; 4:2480. [PMID: 24048253 DOI: 10.1038/ncomms3480] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2013] [Accepted: 08/21/2013] [Indexed: 02/08/2023] Open
Abstract
Reprogramming somatic cells into induced pluripotent stem cells (iPSCs) has provided huge insight into the pathways, mechanisms and transcription factors that control differentiation. Here we use high-throughput RT-PCR technology to take a snapshot of splicing changes in the full spectrum of high- and low-expressed genes during induction of fibroblasts, from several donors, into iPSCs and their subsequent redifferentiation. We uncover a programme of concerted alternative splicing changes involved in late mesoderm differentiation and controlled by key splicing regulators MBNL1 and RBFOX2. These critical splicing adjustments arise early in vertebrate evolution and remain fixed in at least 10 genes (including PLOD2, CLSTN1, ATP2A1, PALM, ITGA6, KIF13A, FMNL3, PPIP5K1, MARK2 and FNIP1), implying that vertebrates require alternative splicing to fully implement the instructions of transcriptional control networks.
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Picchio L, Plantie E, Renaud Y, Poovthumkadavil P, Jagla K. Novel Drosophila model of myotonic dystrophy type 1: phenotypic characterization and genome-wide view of altered gene expression. Hum Mol Genet 2013; 22:2795-810. [PMID: 23525904 DOI: 10.1093/hmg/ddt127] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Myotonic dystrophy type 1 (DM1) is a multisystemic RNA-dominant disorder characterized by myotonia and muscle degeneration. In DM1 patients, the mutant DMPK transcripts containing expanded CUG repeats form nuclear foci and sequester the Muscleblind-like 1 splicing factor, resulting in mis-splicing of its targets. However, several pathological defects observed in DM1 and their link with disease progression remain poorly understood. In an attempt to fill this gap, we generated inducible transgenic Drosophila lines with increasing number of CTG repeats. Targeting the expression of these repeats to the larval muscles recapitulated in a repeat-size-dependent manner the major DM1 symptoms such as muscle hypercontraction, splitting of muscle fibers, reduced fiber size or myoblast fusion defects. Comparative transcriptional profiling performed on the generated DM1 lines and on the muscleblind (mbl)-RNAi line revealed that nuclear accumulation of toxic CUG repeats can affect gene expression independently of splicing or Mbl sequestration. Also, in mblRNAi contexts, the largest portion of deregulated genes corresponded to single-transcript genes, revealing an unexpected impact of the indirect influence of mbl on gene expression. Among the single-transcript Mbl targets is Muscle protein 20 involved in myoblast fusion and causing the reduced number of nuclei in muscles of mblRNAi larvae. Finally, by combining in silico prediction of Mbl targets with mblRNAi microarray data, we found the calcium pump dSERCA as a Mbl splice target and show that the membrane dSERCA isoform is sufficient to rescue a DM1-induced hypercontraction phenotype in a Drosophila model.
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Affiliation(s)
- Lucie Picchio
- GReD Genetics, Reproduction and Development laboratory, INSERM U1103, CNRS UMR6293, University of Clermont-Ferrand, 28 place Henri Dunant, 63000 Clermont-Ferrand, France
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Malatesta M, Giagnacovo M, Costanzo M, Cisterna B, Cardani R, Meola G. Muscleblind-like1 undergoes ectopic relocation in the nuclei of skeletal muscles in myotonic dystrophy and sarcopenia. Eur J Histochem 2013; 57:e15. [PMID: 23807294 PMCID: PMC3794341 DOI: 10.4081/ejh.2013.e15] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2013] [Revised: 02/13/2013] [Accepted: 02/14/2013] [Indexed: 01/24/2023] Open
Abstract
Muscleblind-like 1 (MBNL1) is an alternative splicing factor involved in postnatal development of skeletal muscles and heart in humans and mice, and its deregulation is known to be pivotal in the onset and development of myotonic dystrophy (DM). In fact, in DM patients this protein is ectopically sequestered into intranuclear foci, thus compromising the regulation of the alternative splicing of several genes. However, despite the numerous biochemical and molecular studies, scarce attention has been paid to the intranuclear location of MBNL1 outside the foci, although previous data demonstrated that in DM patients various splicing and cleavage factors undergo an abnormal intranuclear distribution suggestive of impaired RNA processing. Interestingly, these nuclear alterations strongly remind those observed in sarcopenia i.e., the loss of muscle mass and function which physiologically occurs during ageing. On this basis, in the present investigation the ultrastructural localization of MBNL1 was analyzed in the myonuclei of skeletal muscles from healthy and DM patients as well as from adult and old (sarcopenic) mice, in the attempt to elucidate possible changes in its distribution and amount. Our data demonstrate that in both dystrophic and sarcopenic muscles MBNL1 undergoes intranuclear relocation, accumulating in its usual functional sites but also ectopically moving to domains which are usually devoid of this protein in healthy adults. This accumulation/delocalization could contribute to hamper the functionality of the whole splicing machinery, leading to a lower nuclear metabolic activity and, consequently, to a less efficient protein synthesis. Moreover, the similar nuclear alterations found in DM and sarcopenia may account for the similar muscle tissue features (myofibre atrophy, fibre size variability and centrally located nuclei), and, in general, for the aging-reminiscent phenotype observed in DM patients.
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Affiliation(s)
- M Malatesta
- Dipartimento di Scienze Neurologiche, Neuropsicologiche, Morfologiche e Motorie, Sezione di Anatomia e Istologia, Università di Verona, 37134 Verona, Italy.
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Udd B, Krahe R. The myotonic dystrophies: molecular, clinical, and therapeutic challenges. Lancet Neurol 2012; 11:891-905. [DOI: 10.1016/s1474-4422(12)70204-1] [Citation(s) in RCA: 335] [Impact Index Per Article: 27.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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Heissler SM, Manstein DJ. Nonmuscle myosin-2: mix and match. Cell Mol Life Sci 2012; 70:1-21. [PMID: 22565821 PMCID: PMC3535348 DOI: 10.1007/s00018-012-1002-9] [Citation(s) in RCA: 160] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2012] [Revised: 04/16/2012] [Accepted: 04/17/2012] [Indexed: 12/31/2022]
Abstract
Members of the nonmuscle myosin-2 (NM-2) family of actin-based molecular motors catalyze the conversion of chemical energy into directed movement and force thereby acting as central regulatory components of the eukaryotic cytoskeleton. By cyclically interacting with adenosine triphosphate and F-actin, NM-2 isoforms promote cytoskeletal force generation in established cellular processes like cell migration, shape changes, adhesion dynamics, endo- and exo-cytosis, and cytokinesis. Novel functions of the NM-2 family members in autophagy and viral infection are emerging, making NM-2 isoforms regulators of nearly all cellular processes that require the spatiotemporal organization of cytoskeletal scaffolding. Here, we assess current views about the role of NM-2 isoforms in these activities including the tight regulation of NM-2 assembly and activation through phosphorylation and how NM-2-mediated changes in cytoskeletal dynamics and mechanics affect cell physiological functions in health and disease.
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Affiliation(s)
- Sarah M. Heissler
- Institute for Biophysical Chemistry, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany
| | - Dietmar J. Manstein
- Institute for Biophysical Chemistry, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany
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