1
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Ishtayeh H, Galves M, Barnatan TT, Berdichevsky Y, Amer‐Sarsour F, Pasmanik‐Chor M, Braverman I, Blumen SC, Ashkenazi A. Oculopharyngeal muscular dystrophy mutations link the RNA-binding protein HNRNPQ to autophagosome biogenesis. Aging Cell 2023; 22:e13949. [PMID: 37559347 PMCID: PMC10577562 DOI: 10.1111/acel.13949] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2023] [Revised: 06/22/2023] [Accepted: 07/15/2023] [Indexed: 08/11/2023] Open
Abstract
Autophagy is an intracellular degradative process with an important role in cellular homeostasis. Here, we show that the RNA binding protein (RBP), heterogeneous nuclear ribonucleoprotein Q (HNRNPQ)/SYNCRIP is required to stimulate early events in autophagosome biogenesis, in particular the induction of VPS34 kinase by ULK1-mediated beclin 1 phosphorylation. The RBPs HNRNPQ and poly(A) binding protein nuclear 1 (PABPN1) form a regulatory network that controls the turnover of distinct autophagy-related (ATG) proteins. We also show that oculopharyngeal muscular dystrophy (OPMD) mutations engender a switch from autophagosome stimulation to autophagosome inhibition by impairing PABPN1 and HNRNPQ control of the level of ULK1. The overexpression of HNRNPQ in OPMD patient-derived cells rescues the defective autophagy in these cells. Our data reveal a regulatory mechanism of autophagy induction that is compromised by PABPN1 disease mutations, and may thus further contribute to their deleterious effects.
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Affiliation(s)
- Hasan Ishtayeh
- The Department of Cell and Developmental Biology, Faculty of MedicineTel Aviv UniversityTel AvivIsrael
| | - Margarita Galves
- The Department of Cell and Developmental Biology, Faculty of MedicineTel Aviv UniversityTel AvivIsrael
| | - Tania T. Barnatan
- The Department of Cell and Developmental Biology, Faculty of MedicineTel Aviv UniversityTel AvivIsrael
| | - Yevgeny Berdichevsky
- The Department of Cell and Developmental Biology, Faculty of MedicineTel Aviv UniversityTel AvivIsrael
| | - Fatima Amer‐Sarsour
- The Department of Cell and Developmental Biology, Faculty of MedicineTel Aviv UniversityTel AvivIsrael
| | - Metsada Pasmanik‐Chor
- Bioinformatics Unit, G.S. Wise Faculty of Life ScienceTel Aviv UniversityTel AvivIsrael
| | - Itzhak Braverman
- Department of Otolaryngology, Head and Neck SurgeryHillel Yaffe Medical CenterHaderaIsrael
- Rappaport Faculty of Medicine, TechnionHaifaIsrael
| | - Sergiu C. Blumen
- Rappaport Faculty of Medicine, TechnionHaifaIsrael
- Department of NeurologyHillel Yaffe Medical CenterHaderaIsrael
| | - Avraham Ashkenazi
- The Department of Cell and Developmental Biology, Faculty of MedicineTel Aviv UniversityTel AvivIsrael
- Sagol School of NeuroscienceTel Aviv UniversityTel AvivIsrael
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2
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Li Z, Wei H, Hu D, Li X, Guo Y, Ding X, Guo H, Zhang L. Research Progress on the Structural and Functional Roles of hnRNPs in Muscle Development. Biomolecules 2023; 13:1434. [PMID: 37892116 PMCID: PMC10604023 DOI: 10.3390/biom13101434] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2023] [Revised: 09/19/2023] [Accepted: 09/20/2023] [Indexed: 10/29/2023] Open
Abstract
Heterogeneous nuclear ribonucleoproteins (hnRNPs) are a superfamily of RNA-binding proteins consisting of more than 20 members. These proteins play a crucial role in various biological processes by regulating RNA splicing, transcription, and translation through their binding to RNA. In the context of muscle development and regeneration, hnRNPs are involved in a wide range of regulatory mechanisms, including alternative splicing, transcription regulation, miRNA regulation, and mRNA stability regulation. Recent studies have also suggested a potential association between hnRNPs and muscle-related diseases. In this report, we provide an overview of our current understanding of how hnRNPs regulate RNA metabolism and emphasize the significance of the key members of the hnRNP family in muscle development. Furthermore, we explore the relationship between the hnRNP family and muscle-related diseases.
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Affiliation(s)
| | | | | | | | | | | | | | - Linlin Zhang
- Key Laboratory of Animal Breeding and Healthy Livestock Farming, College of Animal Science and Veterinary Medicine, Tianjin Agricultural University, Tianjin 300392, China; (Z.L.); (H.W.); (D.H.); (X.L.); (Y.G.); (X.D.); (H.G.)
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3
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Okumura H, Itoh SG, Zen H, Nakamura K. Dissociation process of polyalanine aggregates by free electron laser irradiation. PLoS One 2023; 18:e0291093. [PMID: 37683014 PMCID: PMC10491298 DOI: 10.1371/journal.pone.0291093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Accepted: 08/22/2023] [Indexed: 09/10/2023] Open
Abstract
Polyalanine (polyA) disease-causative proteins with an expansion of alanine repeats can be aggregated. Although curative treatments for polyA diseases have not been explored, the dissociation of polyA aggregates likely reduces the cytotoxicity of polyA. Mid-infrared free electron laser (FEL) successfully dissociated multiple aggregates. However, whether the FEL dissociates polyA aggregates like other aggregates has not been tested. Here, we show that FEL at 6.1 μm experimentally weakened the extent of aggregation of a peptide with 13 alanine repeats (13A), and the irradiated 13A exerted lesser cytotoxicity to neuron-like cells than non-irradiated 13A. Then, we applied molecular dynamics (MD) simulation to follow the dissociation process by FEL. We successfully observed how the intermolecular β-sheet of polyA aggregates was dissociated and separated into monomers with helix structures upon FEL irradiation. After the dissociation by FEL, water molecules inhibited the reformation of polyA aggregates. We recently verified the same dissociation process using FEL-treated amyloid-β aggregates. Thus, a common mechanism underlies the dissociation of different protein aggregates that cause different diseases, polyA disease and Alzheimer's disease. However, MD simulation indicated that polyA aggregates are less easily dissociated than amyloid-β aggregates and require longer laser irradiation due to hydrophobic alanine repeats.
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Affiliation(s)
- Hisashi Okumura
- Exploratory Research Center on Life and Living Systems (ExCELLS), National Institutes of Natural Sciences, Okazaki, Aichi, Japan
- Institute for Molecular Science, National Institutes of Natural Sciences, Okazaki, Aichi, Japan
- Graduate Institute for Advanced Studies, SOKENDAI, Okazaki, Aichi, Japan
| | - Satoru G Itoh
- Exploratory Research Center on Life and Living Systems (ExCELLS), National Institutes of Natural Sciences, Okazaki, Aichi, Japan
- Institute for Molecular Science, National Institutes of Natural Sciences, Okazaki, Aichi, Japan
- Graduate Institute for Advanced Studies, SOKENDAI, Okazaki, Aichi, Japan
| | - Heishun Zen
- Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Kyoto, Japan
| | - Kazuhiro Nakamura
- Department of Laboratory Sciences, Gunma University Graduate School of Health Sciences, Maebashi, Gunma, Japan
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4
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Zhang Y, Zeuthen C, Zhu C, Wu F, Mezzell AT, Whitlow TJ, Choo HJ, Vest KE. Pharyngeal pathology in a mouse model of oculopharyngeal muscular dystrophy is associated with impaired basal autophagy in myoblasts. Front Cell Dev Biol 2022; 10:986930. [PMID: 36313551 PMCID: PMC9614327 DOI: 10.3389/fcell.2022.986930] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Accepted: 09/26/2022] [Indexed: 11/05/2023] Open
Abstract
Oculopharyngeal muscular dystrophy (OPMD) is a late-onset dominant disease that primarily affects craniofacial muscles. Despite the fact that the genetic cause of OPMD is known to be expansion mutations in the gene encoding the nuclear polyadenosine RNA binding protein PABPN1, the molecular mechanisms of pathology are unknown and no pharmacologic treatments are available. Due to the limited availability of patient tissues, several animal models have been employed to study the pathology of OPMD. However, none of these models have demonstrated functional deficits in the muscles of the pharynx, which are predominantly affected by OPMD. Here, we used a knock-in mouse model of OPMD, Pabpn1 +/A17 , that closely genocopies patients. In Pabpn1 +/A17 mice, we detected impaired pharyngeal muscle function, and impaired pharyngeal satellite cell proliferation and fusion. Molecular studies revealed that basal autophagy, which is required for normal satellite cell function, is higher in pharynx-derived myoblasts than in myoblasts derived from limb muscles. Interestingly, basal autophagy is impaired in cells derived from Pabpn1 +/A17 mice. Pabpn1 knockdown in pharyngeal myoblasts failed to recapitulate the autophagy defect detected in Pabpn1 +/A17 myoblasts suggesting that loss of PABPN1 function does not contribute to the basal autophagy defect. Taken together, these studies provide the first evidence for pharyngeal muscle and satellite cell pathology in a mouse model of OPMD and suggest that aberrant gain of PABPN1 function contributes to the craniofacial pathology in OPMD.
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Affiliation(s)
- Yu Zhang
- Department of Molecular Genetics, Biochemistry and Microbiology, University of Cincinnati College of Medicine, Cincinnati, OH, United States
| | - Christopher Zeuthen
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA, United States
| | - Carol Zhu
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA, United States
| | - Fang Wu
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA, United States
| | - Allison T. Mezzell
- Department of Molecular Genetics, Biochemistry and Microbiology, University of Cincinnati College of Medicine, Cincinnati, OH, United States
| | - Thomas J. Whitlow
- Department of Molecular Genetics, Biochemistry and Microbiology, University of Cincinnati College of Medicine, Cincinnati, OH, United States
| | - Hyojung J. Choo
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA, United States
| | - Katherine E. Vest
- Department of Molecular Genetics, Biochemistry and Microbiology, University of Cincinnati College of Medicine, Cincinnati, OH, United States
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5
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Ribot C, Soler C, Chartier A, Al Hayek S, Naït-Saïdi R, Barbezier N, Coux O, Simonelig M. Activation of the ubiquitin-proteasome system contributes to oculopharyngeal muscular dystrophy through muscle atrophy. PLoS Genet 2022; 18:e1010015. [PMID: 35025870 PMCID: PMC8791501 DOI: 10.1371/journal.pgen.1010015] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Revised: 01/26/2022] [Accepted: 01/01/2022] [Indexed: 12/05/2022] Open
Abstract
Oculopharyngeal muscular dystrophy (OPMD) is a late-onset disorder characterized by progressive weakness and degeneration of specific muscles. OPMD is due to extension of a polyalanine tract in poly(A) binding protein nuclear 1 (PABPN1). Aggregation of the mutant protein in muscle nuclei is a hallmark of the disease. Previous transcriptomic analyses revealed the consistent deregulation of the ubiquitin-proteasome system (UPS) in OPMD animal models and patients, suggesting a role of this deregulation in OPMD pathogenesis. Subsequent studies proposed that UPS contribution to OPMD involved PABPN1 aggregation. Here, we use a Drosophila model of OPMD to address the functional importance of UPS deregulation in OPMD. Through genome-wide and targeted genetic screens we identify a large number of UPS components that are involved in OPMD. Half dosage of UPS genes reduces OPMD muscle defects suggesting a pathological increase of UPS activity in the disease. Quantification of proteasome activity confirms stronger activity in OPMD muscles, associated with degradation of myofibrillar proteins. Importantly, improvement of muscle structure and function in the presence of UPS mutants does not correlate with the levels of PABPN1 aggregation, but is linked to decreased degradation of muscle proteins. Oral treatment with the proteasome inhibitor MG132 is beneficial to the OPMD Drosophila model, improving muscle function although PABPN1 aggregation is enhanced. This functional study reveals the importance of increased UPS activity that underlies muscle atrophy in OPMD. It also provides a proof-of-concept that inhibitors of proteasome activity might be an attractive pharmacological approach for OPMD. Oculopharyngeal muscular dystrophy (OPMD) is a genetic disease characterized by progressive weakness of specific muscles, leading to swallowing difficulties (dysphagia), eyelid drooping (ptosis) and walking difficulties at later stages. No drug treatments are currently available. OPMD is due to mutations in a nuclear protein called poly(A) binding protein nuclear 1 (PABPN1) that is involved in processing of different classes of RNAs in the nucleus. We have used an animal model of OPMD that we have developed in the fly Drosophila to investigate the role in OPMD of the ubiquitin-proteasome system, a pathway specialized in protein degradation. We report an increased activity of the ubiquitin-proteasome system that is associated with degradation of muscular proteins in the OPMD Drosophila model. We propose that higher activity of the ubiquitin-proteasome system leads to muscle atrophy in OPMD. Importantly, oral treatment of this OPMD animal model with an inhibitor of proteasome activity reduces muscle defects. A number of proteasome inhibitors are approved drugs used in clinic against cancers, therefore our results provide a proof-of-concept that inhibitors of proteasome might be of interest in future treatments of OPMD.
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Affiliation(s)
- Cécile Ribot
- mRNA Regulation and Development, Institute of Human Genetics, UMR9002 CNRS-Univ Montpellier, Montpellier, France
| | - Cédric Soler
- mRNA Regulation and Development, Institute of Human Genetics, UMR9002 CNRS-Univ Montpellier, Montpellier, France
| | - Aymeric Chartier
- mRNA Regulation and Development, Institute of Human Genetics, UMR9002 CNRS-Univ Montpellier, Montpellier, France
| | - Sandy Al Hayek
- GReD Laboratory, Clermont-Auvergne University, INSERM U1103, CNRS UMR6293, Clermont-Ferrand, France
| | - Rima Naït-Saïdi
- mRNA Regulation and Development, Institute of Human Genetics, UMR9002 CNRS-Univ Montpellier, Montpellier, France
| | - Nicolas Barbezier
- mRNA Regulation and Development, Institute of Human Genetics, UMR9002 CNRS-Univ Montpellier, Montpellier, France
| | - Olivier Coux
- Ubiquitin-proteasome system and cell cycle control, Montpellier Cell Biology Research Center, UMR5237 CNRS-Univ Montpellier, Montpellier, France
| | - Martine Simonelig
- mRNA Regulation and Development, Institute of Human Genetics, UMR9002 CNRS-Univ Montpellier, Montpellier, France
- * E-mail:
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6
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Iizuka Y, Owada R, Kawasaki T, Hayashi F, Sonoyama M, Nakamura K. Toxicity of internalized polyalanine to cells depends on aggregation. Sci Rep 2021; 11:23441. [PMID: 34873226 PMCID: PMC8648788 DOI: 10.1038/s41598-021-02889-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Accepted: 11/24/2021] [Indexed: 12/23/2022] Open
Abstract
In polyalanine (PA) diseases, the disease-causing transcription factors contain an expansion of alanine repeats. While aggregated proteins that are responsible for the pathogenesis of neurodegenerative disorders show cell-to-cell propagation and thereby exert toxic effects on the recipient cells, whether this is also the case with expanded PA has not been studied. It is also not known whether the internalized PA is toxic to recipient cells based on the degree of aggregation. In this study, we therefore prepared different degrees of aggregation of a peptide having 13 alanine repeats without flanking sequences of PA disease-causative proteins (13A). The aggregated 13A was spontaneously taken up by neuron-like cultured cells. Functionally, strong aggregates but not weak aggregates displayed a deficit in neuron-like differentiation in vitro. Moreover, the injection of strong but not weak 13A aggregates into the ventricle of mice during the neonatal stage led to enhanced spontaneous motor activity later in life. Thus, PA in the extracellular space has the potential to enter adjacent cells, and may exert toxicity depending on the degree of aggregation.
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Affiliation(s)
- Yutaro Iizuka
- Department of Laboratory Sciences, Gunma University Graduate School of Health Sciences, 3-39-22, Showa-machi, Maebashi, Gunma, 371-8511, Japan
| | - Ryuji Owada
- Department of Laboratory Sciences, Gunma University Graduate School of Health Sciences, 3-39-22, Showa-machi, Maebashi, Gunma, 371-8511, Japan
| | - Takayasu Kawasaki
- Accelerator Laboratory, High Energy Accelerator Research Organization, 1-1 Oho, Tsukuba, Ibaraki, 305-0801, Japan
| | - Fumio Hayashi
- Center for Instrumental Analysis, Organization for Promotion of Research and University Industry Collaboration, Gunma University, 1-5-1, Tenjin-cho, Kiryu, Gunma, 376-8515, Japan
| | - Masashi Sonoyama
- Division of Molecular Science, Faculty of Science and Technology, Gunma University, 1-5-1 Tenjin-cho, Kiryu, Gunma, 376-8515, Japan.,Gunma University Initiative for Advanced Research (GIAR), Gunma University, 1-5-1 Tenjin-cho, Kiryu, Gunma, 376-8515, Japan.,Gunma University Center for Food Science and Wellness (GUCFW), Gunma University, 1-5-1 Tenjin-cho, Kiryu, Gunma, 376-8515, Japan
| | - Kazuhiro Nakamura
- Department of Laboratory Sciences, Gunma University Graduate School of Health Sciences, 3-39-22, Showa-machi, Maebashi, Gunma, 371-8511, Japan.
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7
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Malerba A, Klein P, Lu-Nguyen N, Cappellari O, Strings-Ufombah V, Harbaran S, Roelvink P, Suhy D, Trollet C, Dickson G. Established PABPN1 intranuclear inclusions in OPMD muscle can be efficiently reversed by AAV-mediated knockdown and replacement of mutant expanded PABPN1. Hum Mol Genet 2020; 28:3301-3308. [PMID: 31294444 DOI: 10.1093/hmg/ddz167] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2019] [Revised: 06/21/2019] [Accepted: 07/08/2019] [Indexed: 11/12/2022] Open
Abstract
Oculopharyngeal muscular dystrophy (OPMD) is a rare autosomal dominant late-onset muscular dystrophy affecting approximately 1:100 000 individuals in Europe. OPMD is mainly characterized by progressive eyelid drooping (ptosis) and dysphagia although muscles of the limbs can also be affected late in life. This muscle disease is due to a trinucleotide repeat expansion in the polyA-binding protein nuclear-1 gene. Patients express a protein with an 11-18 alanine tract that is misfolded and prone to form intranuclear inclusions, which are the hallmark of the disease. Other features of OPMD include muscle fibrosis and atrophy in affected muscles. Currently, no pharmacological treatments are available, and OPMD patients can only be referred to surgeons for cricopharyngeal myotomy or corrective surgery of extraocular muscles to ease ptosis. We recently tested a two-AAV `silence' and `replace' vector-based gene therapy treatment in a mouse model of OPMD. We demonstrate here that this gene therapy approach can revert already established insoluble aggregates and partially rescues the muscle from atrophy, which are both crucially important since in most cases OPMD patients already have an established disease when diagnosed. This strategy also prevents the formation of muscle fibrosis and stabilizes the muscle strength to the level of healthy muscles. Furthermore, we show here that similar results can be obtained using a single AAV vector incorporating both the `silence' and `replace' cassettes. These results further support the application of a gene therapy approach as a novel treatment for OPMD in humans.
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Affiliation(s)
- Alberto Malerba
- Centres of Gene and Cell Therapy and Biomedical Sciences, School of Biological Sciences, Royal Holloway, University of London, Egham TW20 0EX, Surrey, UK
| | - Pierre Klein
- Sorbonne Université, INSERM, Association Institut de Myologie, Centre de Recherche en Myologie, UMRS974, 47 bd de l'Hôpital, 75013 Paris, France
| | - Ngoc Lu-Nguyen
- Centres of Gene and Cell Therapy and Biomedical Sciences, School of Biological Sciences, Royal Holloway, University of London, Egham TW20 0EX, Surrey, UK
| | - Ornella Cappellari
- Comparative Biomedical Sciences, Royal Veterinary College, London NW1 0TU, UK
| | | | | | | | - David Suhy
- Benitec Biopharma, Hayward, CA 94545, USA
| | - Capucine Trollet
- Sorbonne Université, INSERM, Association Institut de Myologie, Centre de Recherche en Myologie, UMRS974, 47 bd de l'Hôpital, 75013 Paris, France
| | - George Dickson
- Centres of Gene and Cell Therapy and Biomedical Sciences, School of Biological Sciences, Royal Holloway, University of London, Egham TW20 0EX, Surrey, UK
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8
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Picchiarelli G, Dupuis L. Role of RNA Binding Proteins with prion-like domains in muscle and neuromuscular diseases. Cell Stress 2020; 4:76-91. [PMID: 32292882 PMCID: PMC7146060 DOI: 10.15698/cst2020.04.217] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
A number of neuromuscular and muscular diseases, including amyotrophic lateral sclerosis (ALS), spinal muscular atrophy (SMA) and several myopathies, are associated to mutations in related RNA-binding proteins (RBPs), including TDP-43, FUS, MATR3 or hnRNPA1/B2. These proteins harbor similar modular primary sequence with RNA binding motifs and low complexity domains, that enables them to phase separate and create liquid microdomains. These RBPs have been shown to critically regulate multiple events of RNA lifecycle, including transcriptional events, splicing and RNA trafficking and sequestration. Here, we review the roles of these disease-related RBPs in muscle and motor neurons, and how their dysfunction in these cell types might contribute to disease.
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Affiliation(s)
- Gina Picchiarelli
- Université de Strasbourg, INSERM, Mécanismes Centraux et Périphériques de la Neurodégénérescence, UMR_S 1118, Strasbourg, France
| | - Luc Dupuis
- Université de Strasbourg, INSERM, Mécanismes Centraux et Périphériques de la Neurodégénérescence, UMR_S 1118, Strasbourg, France
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9
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Cascarina SM, Ross ED. Natural and pathogenic protein sequence variation affecting prion-like domains within and across human proteomes. BMC Genomics 2020; 21:23. [PMID: 31914925 PMCID: PMC6947906 DOI: 10.1186/s12864-019-6425-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2019] [Accepted: 12/23/2019] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Impaired proteostatic regulation of proteins with prion-like domains (PrLDs) is associated with a variety of human diseases including neurodegenerative disorders, myopathies, and certain forms of cancer. For many of these disorders, current models suggest a prion-like molecular mechanism of disease, whereby proteins aggregate and spread to neighboring cells in an infectious manner. The development of prion prediction algorithms has facilitated the large-scale identification of PrLDs among "reference" proteomes for various organisms. However, the degree to which intraspecies protein sequence diversity influences predicted prion propensity has not been systematically examined. RESULTS Here, we explore protein sequence variation introduced at genetic, post-transcriptional, and post-translational levels, and its influence on predicted aggregation propensity for human PrLDs. We find that sequence variation is relatively common among PrLDs and in some cases can result in relatively large differences in predicted prion propensity. Sequence variation introduced at the post-transcriptional level (via alternative splicing) also commonly affects predicted aggregation propensity, often by direct inclusion or exclusion of a PrLD. Finally, analysis of a database of sequence variants associated with human disease reveals a number of mutations within PrLDs that are predicted to increase prion propensity. CONCLUSIONS Our analyses expand the list of candidate human PrLDs, quantitatively estimate the effects of sequence variation on the aggregation propensity of PrLDs, and suggest the involvement of prion-like mechanisms in additional human diseases.
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Affiliation(s)
- Sean M Cascarina
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO, 80523, USA
| | - Eric D Ross
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO, 80523, USA.
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10
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Mitochondrial localization of PABPN1 in oculopharyngeal muscular dystrophy. J Transl Med 2019; 99:1728-1740. [PMID: 30894671 DOI: 10.1038/s41374-019-0243-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Revised: 02/09/2019] [Accepted: 02/16/2019] [Indexed: 11/09/2022] Open
Abstract
Oculopharyngeal muscular dystrophy (OPMD) is a late-onset disorder characterized by ptosis, dysphagia, and weakness of proximal limbs. OPMD is caused by the expansion of polyalanine in poly(A)-binding protein, nuclear 1 (PABPN1). Although mitochondrial abnormality has been proposed as the possible etiology, the molecular pathogenesis is still poorly understood. The aim of the study was to specify the mechanism by which expanded PABPN1 causes mitochondrial dysfunction in OPMD. We evaluated whether transgenic mouse model of OPMD, by expressing expanded PABPN1, indeed causes mitochondrial abnormality associated with muscle degeneration. We also investigated the mechanism by which expanded PABPN1 would cause mitochondrial dysfunction in the mouse and cell models of OPMD. Mitochondrial localization of PABPN1 was observed in the muscle fibers of patients with OPMD. Moreover, abnormal accumulation of PABPN1 on the inner membrane of mitochondria and reduced expression of OXPHOS complexes were detected in the muscle fibers of the transgenic mice expressing expanded human PABPN1 with a 13-alanine stretch. In cells expressing PABPN1 with a 10-alanine or 18-alanine stretch, both types of PABPN1 accumulated in the mitochondria and interacted with TIM23 mitochondrial protein import complex, but PABPN1 with 18-alanine stretch decreased the cell viability and aggresome formation. We proposed that the abnormal accumulation of expanded PABPN1 in mitochondria may be associated with mitochondrial abnormality in OPMD.
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11
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Phillips BL, Banerjee A, Sanchez BJ, Di Marco S, Gallouzi IE, Pavlath GK, Corbett AH. Post-transcriptional regulation of Pabpn1 by the RNA binding protein HuR. Nucleic Acids Res 2019; 46:7643-7661. [PMID: 29939290 PMCID: PMC6125628 DOI: 10.1093/nar/gky535] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Accepted: 06/08/2018] [Indexed: 01/14/2023] Open
Abstract
RNA processing is critical for proper spatial and temporal control of gene expression. The ubiquitous nuclear polyadenosine RNA binding protein, PABPN1, post-transcriptionally regulates multiple steps of gene expression. Mutations in the PABPN1 gene expanding an N-terminal alanine tract in the PABPN1 protein from 10 alanines to 11–18 alanines cause the muscle-specific disease oculopharyngeal muscular dystrophy (OPMD), which affects eyelid, pharynx, and proximal limb muscles. Previous work revealed that the Pabpn1 transcript is unstable, contributing to low steady-state Pabpn1 mRNA and protein levels in vivo, specifically in skeletal muscle, with even lower levels in muscles affected in OPMD. Thus, low levels of PABPN1 protein could predispose specific tissues to pathology in OPMD. However, no studies have defined the mechanisms that regulate Pabpn1 expression. Here, we define multiple cis-regulatory elements and a trans-acting factor, HuR, which regulate Pabpn1 expression specifically in mature muscle in vitro and in vivo. We exploit multiple models including C2C12 myotubes, primary muscle cells, and mice to determine that HuR decreases Pabpn1 expression. Overall, we have uncovered a mechanism in mature muscle that negatively regulates Pabpn1 expression in vitro and in vivo, which could provide insight to future studies investigating therapeutic strategies for OPMD treatment.
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Affiliation(s)
- Brittany L Phillips
- Department of Biology, Emory University, Atlanta, GA 30322, USA.,Department of Pharmacology, Emory University School of Medicine, Atlanta, GA 30322, USA.,Genetics and Molecular Biology Graduate Program, Emory University, Atlanta, GA 30322, USA
| | - Ayan Banerjee
- Department of Biology, Emory University, Atlanta, GA 30322, USA
| | - Brenda J Sanchez
- Department of Biochemistry, Goodman Cancer Center, McGill University, Montreal, Quebec, Canada
| | - Sergio Di Marco
- Department of Biochemistry, Goodman Cancer Center, McGill University, Montreal, Quebec, Canada
| | - Imed-Eddine Gallouzi
- Department of Biochemistry, Goodman Cancer Center, McGill University, Montreal, Quebec, Canada.,Hamad Bin Khalifa University (HBKU), Life Sciences Division, College of Sciences and Engineering, Education City, Doha, Qatar
| | - Grace K Pavlath
- Department of Pharmacology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Anita H Corbett
- Department of Biology, Emory University, Atlanta, GA 30322, USA
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12
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Banerjee A, Phillips BL, Deng Q, Seyfried NT, Pavlath GK, Vest KE, Corbett AH. Proteomic analysis reveals that wildtype and alanine-expanded nuclear poly(A)-binding protein exhibit differential interactions in skeletal muscle. J Biol Chem 2019; 294:7360-7376. [PMID: 30837270 DOI: 10.1074/jbc.ra118.007287] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2018] [Revised: 02/19/2019] [Indexed: 12/22/2022] Open
Abstract
Oculopharyngeal muscular dystrophy (OPMD) is a late-onset, primarily autosomal dominant disease caused by a short GCN expansion in the PABPN1 (polyadenylate-binding protein nuclear 1) gene that results in an alanine expansion at the N terminus of the PABPN1 protein. Expression of alanine-expanded PABPN1 is linked to the formation of nuclear aggregates in tissues from individuals with OPMD. However, as with other nuclear aggregate-associated diseases, controversy exists over whether these aggregates are the direct cause of pathology. An emerging hypothesis is that a loss of PABPN1 function and/or aberrant protein interactions contribute to pathology in OPMD. Here, we present the first global proteomic analysis of the protein interactions of WT and alanine-expanded PABPN1 in skeletal muscle tissue. These data provide both insight into the function of PABPN1 in muscle and evidence that the alanine expansion alters the protein-protein interactions of PABPN1. We extended this analysis to demonstrate altered complex formation with and loss of function of TDP-43 (TAR DNA-binding protein 43), which we show interacts with alanine-expanded but not WT PABPN1. The results from our study support a model where altered protein interactions with alanine-expanded PABPN1 that lead to loss or gain of function could contribute to pathology in OPMD.
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Affiliation(s)
| | - Brittany L Phillips
- From the Department of Biology and.,the Graduate Program in Genetics and Molecular Biology, Emory University, Atlanta, Georgia 30322
| | - Quidong Deng
- the Department of Biochemistry, Center for Neurodegenerative Diseases and
| | | | - Grace K Pavlath
- the Department of Pharmacology, Emory University School of Medicine, Atlanta, Georgia 30322, and
| | - Katherine E Vest
- the Department of Molecular Genetics, Biochemistry & Microbiology, University of Cincinnati College of Medicine, Cincinnati, Ohio 45267
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13
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Harish P, Dickson G, Malerba A. Advances in emerging therapeutics for oculopharyngeal muscular dystrophy. Expert Opin Orphan Drugs 2018. [DOI: 10.1080/21678707.2018.1536542] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Affiliation(s)
- Pradeep Harish
- School of Biological Sciences, Centres of Gene and Cell therapy and Biomedical sciences, Royal Holloway University of London, Egham, Surrey, UK
| | - George Dickson
- School of Biological Sciences, Centres of Gene and Cell therapy and Biomedical sciences, Royal Holloway University of London, Egham, Surrey, UK
| | - Alberto Malerba
- School of Biological Sciences, Centres of Gene and Cell therapy and Biomedical sciences, Royal Holloway University of London, Egham, Surrey, UK
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14
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Abu-Baker A, Parker A, Ramalingam S, Laganiere J, Brais B, Neri C, Dion P, Rouleau G. Valproic acid is protective in cellular and worm models of oculopharyngeal muscular dystrophy. Neurology 2018; 91:e551-e561. [PMID: 30006409 PMCID: PMC6105050 DOI: 10.1212/wnl.0000000000005942] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Accepted: 05/08/2018] [Indexed: 02/01/2023] Open
Abstract
OBJECTIVE To explore valproic acid (VPA) as a potentially beneficial drug in cellular and worm models of oculopharyngeal muscular dystrophy (OPMD). METHODS Using a combination of live cell imaging and biochemical measures, we evaluated the potential protective effect of VPA in a stable C2C12 muscle cell model of OPMD, in lymphoblastoid cell lines derived from patients with OPMD and in a transgenic Caenorhabditis elegans OPMD model expressing human mutant PABPN1. RESULTS We demonstrated that VPA protects against the toxicity of mutant PABPN1. Of note, we found that VPA confers its long-term protective effects on C2C12 cell survival, proliferation, and differentiation by increasing the acetylated level of histones. Furthermore, VPA enhances the level of histone acetylation in lymphoblastoid cell lines derived from patients with OPMD. Moreover, treatment of nematodes with moderate concentrations of VPA significantly improved the motility of the PABPN-13 Alanines worms. CONCLUSIONS Our results suggest that VPA helps to counteract OPMD-related phenotypes in the cellular and C elegans disease models.
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Affiliation(s)
- Aida Abu-Baker
- From the Montreal Neurological Institute and Hospital (A.A.-B., P.D., G.R.), Ingram School of Nursing, Faculty of Medicine (S.R.), and Department of Neurology and Neurosurgery (G.R.), McGill University, Montreal; CHUM Research Center (A.P.), Montreal; Department of Neuroscience (A.P.), and Ophthalmology Research Hôpital Maisonneuve Rosemont, Laboratoire de Isabelle Brunette (J.L.), University of Montreal; Neuromuscular Group (B.B.), Montreal Neurological Institute and Hospital, McGill University, Montreal, Canada; and Brain C-lab (C.N.), Institute of Biology Paris-Seine, CNRS UMR 8256 Biology of Adaptation & Aging, University Pierre and Marie Curie, Paris, France
| | - Alex Parker
- From the Montreal Neurological Institute and Hospital (A.A.-B., P.D., G.R.), Ingram School of Nursing, Faculty of Medicine (S.R.), and Department of Neurology and Neurosurgery (G.R.), McGill University, Montreal; CHUM Research Center (A.P.), Montreal; Department of Neuroscience (A.P.), and Ophthalmology Research Hôpital Maisonneuve Rosemont, Laboratoire de Isabelle Brunette (J.L.), University of Montreal; Neuromuscular Group (B.B.), Montreal Neurological Institute and Hospital, McGill University, Montreal, Canada; and Brain C-lab (C.N.), Institute of Biology Paris-Seine, CNRS UMR 8256 Biology of Adaptation & Aging, University Pierre and Marie Curie, Paris, France
| | - Siriram Ramalingam
- From the Montreal Neurological Institute and Hospital (A.A.-B., P.D., G.R.), Ingram School of Nursing, Faculty of Medicine (S.R.), and Department of Neurology and Neurosurgery (G.R.), McGill University, Montreal; CHUM Research Center (A.P.), Montreal; Department of Neuroscience (A.P.), and Ophthalmology Research Hôpital Maisonneuve Rosemont, Laboratoire de Isabelle Brunette (J.L.), University of Montreal; Neuromuscular Group (B.B.), Montreal Neurological Institute and Hospital, McGill University, Montreal, Canada; and Brain C-lab (C.N.), Institute of Biology Paris-Seine, CNRS UMR 8256 Biology of Adaptation & Aging, University Pierre and Marie Curie, Paris, France
| | - Janet Laganiere
- From the Montreal Neurological Institute and Hospital (A.A.-B., P.D., G.R.), Ingram School of Nursing, Faculty of Medicine (S.R.), and Department of Neurology and Neurosurgery (G.R.), McGill University, Montreal; CHUM Research Center (A.P.), Montreal; Department of Neuroscience (A.P.), and Ophthalmology Research Hôpital Maisonneuve Rosemont, Laboratoire de Isabelle Brunette (J.L.), University of Montreal; Neuromuscular Group (B.B.), Montreal Neurological Institute and Hospital, McGill University, Montreal, Canada; and Brain C-lab (C.N.), Institute of Biology Paris-Seine, CNRS UMR 8256 Biology of Adaptation & Aging, University Pierre and Marie Curie, Paris, France
| | - Bernard Brais
- From the Montreal Neurological Institute and Hospital (A.A.-B., P.D., G.R.), Ingram School of Nursing, Faculty of Medicine (S.R.), and Department of Neurology and Neurosurgery (G.R.), McGill University, Montreal; CHUM Research Center (A.P.), Montreal; Department of Neuroscience (A.P.), and Ophthalmology Research Hôpital Maisonneuve Rosemont, Laboratoire de Isabelle Brunette (J.L.), University of Montreal; Neuromuscular Group (B.B.), Montreal Neurological Institute and Hospital, McGill University, Montreal, Canada; and Brain C-lab (C.N.), Institute of Biology Paris-Seine, CNRS UMR 8256 Biology of Adaptation & Aging, University Pierre and Marie Curie, Paris, France
| | - Christian Neri
- From the Montreal Neurological Institute and Hospital (A.A.-B., P.D., G.R.), Ingram School of Nursing, Faculty of Medicine (S.R.), and Department of Neurology and Neurosurgery (G.R.), McGill University, Montreal; CHUM Research Center (A.P.), Montreal; Department of Neuroscience (A.P.), and Ophthalmology Research Hôpital Maisonneuve Rosemont, Laboratoire de Isabelle Brunette (J.L.), University of Montreal; Neuromuscular Group (B.B.), Montreal Neurological Institute and Hospital, McGill University, Montreal, Canada; and Brain C-lab (C.N.), Institute of Biology Paris-Seine, CNRS UMR 8256 Biology of Adaptation & Aging, University Pierre and Marie Curie, Paris, France
| | - Patrick Dion
- From the Montreal Neurological Institute and Hospital (A.A.-B., P.D., G.R.), Ingram School of Nursing, Faculty of Medicine (S.R.), and Department of Neurology and Neurosurgery (G.R.), McGill University, Montreal; CHUM Research Center (A.P.), Montreal; Department of Neuroscience (A.P.), and Ophthalmology Research Hôpital Maisonneuve Rosemont, Laboratoire de Isabelle Brunette (J.L.), University of Montreal; Neuromuscular Group (B.B.), Montreal Neurological Institute and Hospital, McGill University, Montreal, Canada; and Brain C-lab (C.N.), Institute of Biology Paris-Seine, CNRS UMR 8256 Biology of Adaptation & Aging, University Pierre and Marie Curie, Paris, France
| | - Guy Rouleau
- From the Montreal Neurological Institute and Hospital (A.A.-B., P.D., G.R.), Ingram School of Nursing, Faculty of Medicine (S.R.), and Department of Neurology and Neurosurgery (G.R.), McGill University, Montreal; CHUM Research Center (A.P.), Montreal; Department of Neuroscience (A.P.), and Ophthalmology Research Hôpital Maisonneuve Rosemont, Laboratoire de Isabelle Brunette (J.L.), University of Montreal; Neuromuscular Group (B.B.), Montreal Neurological Institute and Hospital, McGill University, Montreal, Canada; and Brain C-lab (C.N.), Institute of Biology Paris-Seine, CNRS UMR 8256 Biology of Adaptation & Aging, University Pierre and Marie Curie, Paris, France.
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15
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Liu TY, Chen YC, Jong YJ, Tsai HJ, Lee CC, Chang YS, Chang JG, Chang YF. Muscle developmental defects in heterogeneous nuclear Ribonucleoprotein A1 knockout mice. Open Biol 2017; 7:rsob.160303. [PMID: 28077597 PMCID: PMC5303281 DOI: 10.1098/rsob.160303] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2016] [Accepted: 12/05/2016] [Indexed: 01/18/2023] Open
Abstract
Heterogeneous ribonucleoprotein A1 (hnRNP A1) is crucial for regulating alternative splicing. Its integrated function within an organism has not, however, been identified. We generated hnRNP A1 knockout mice to study the role of hnRNP A1 in vivo. The knockout mice, hnRNP A1−/−, showed embryonic lethality because of muscle developmental defects. The blood pressure and heart rate of the heterozygous mice were higher than those of the wild-type mice, indicating heart function defects. We performed mouse exon arrays to study the muscle development mechanism. The processes regulated by hnRNP A1 included cell adhesion and muscle contraction. The expression levels of muscle development-related genes in hnRNP A1+/− mice were significantly different from those in wild-type mice, as detected using qRT-PCR. We further confirmed the alternative splicing patterns of muscle development-related genes including mef2c, lrrfip1, usp28 and abcc9. Alternative mRNA isoforms of these genes were increased in hnRNP A1+/− mice compared with wild-type mice. Furthermore, we revealed that the functionally similar hnRNP A2/B1 did not compensate for the expression of hnRNP A1 in organisms. In summary, our study demonstrated that hnRNP A1 plays a critical and irreplaceable role in embryonic muscle development by regulating the expression and alternative splicing of muscle-related genes.
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Affiliation(s)
- Ting-Yuan Liu
- Graduate Institute of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan, Republic of China
| | - Yu-Chia Chen
- Graduate Institute of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan, Republic of China
| | - Yuh-Jyh Jong
- Graduate Institute of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan, Republic of China.,Graduate Institute of Clinical Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan, Republic of China.,Departments of Pediatrics and Clinical Laboratory, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan, Republic of China.,Department of Biological Science and Technology, Institute of Molecular Medicine and Bioengineering, College of Biological Science and Technology, National Chiao Tung University, Hsinchu, Taiwan, Republic of China
| | - Huai-Jen Tsai
- Institute of Biomedical Sciences, Mackay Medical College, New Taipei City, Taiwan, Republic of China
| | - Chien-Chin Lee
- Epigenome Research Center, China Medical University, Taichung, Taiwan, Republic of China
| | - Ya-Sian Chang
- Epigenome Research Center, China Medical University, Taichung, Taiwan, Republic of China.,Department of Laboratory Medicine, China Medical University, Taichung, Taiwan, Republic of China.,Department of Medical Laboratory Science and Biotechnology, China Medical University, Taichung, Taiwan, Republic of China
| | - Jan-Gowth Chang
- Epigenome Research Center, China Medical University, Taichung, Taiwan, Republic of China .,Department of Laboratory Medicine, China Medical University, Taichung, Taiwan, Republic of China.,School of Medicine, China Medical University, Taichung, Taiwan, Republic of China
| | - Yung-Fu Chang
- Department of Biomedical Science and Environmental Biology, College of Life Science, Kaohsiung Medical University, Kaohsiung, Taiwan, Republic of China
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16
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Banerjee A, Vest KE, Pavlath GK, Corbett AH. Nuclear poly(A) binding protein 1 (PABPN1) and Matrin3 interact in muscle cells and regulate RNA processing. Nucleic Acids Res 2017; 45:10706-10725. [PMID: 28977530 PMCID: PMC5737383 DOI: 10.1093/nar/gkx786] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Accepted: 08/27/2017] [Indexed: 01/01/2023] Open
Abstract
The polyadenylate binding protein 1 (PABPN1) is a ubiquitously expressed RNA binding protein vital for multiple steps in RNA metabolism. Although PABPN1 plays a critical role in the regulation of RNA processing, mutation of the gene encoding this ubiquitously expressed RNA binding protein causes a specific form of muscular dystrophy termed oculopharyngeal muscular dystrophy (OPMD). Despite the tissue-specific pathology that occurs in this disease, only recently have studies of PABPN1 begun to explore the role of this protein in skeletal muscle. We have used co-immunoprecipitation and mass spectrometry to identify proteins that interact with PABPN1 in mouse skeletal muscles. Among the interacting proteins we identified Matrin 3 (MATR3) as a novel protein interactor of PABPN1. The MATR3 gene is mutated in a form of distal myopathy and amyotrophic lateral sclerosis (ALS). We demonstrate, that like PABPN1, MATR3 is critical for myogenesis. Furthermore, MATR3 controls critical aspects of RNA processing including alternative polyadenylation and intron retention. We provide evidence that MATR3 also binds and regulates the levels of long non-coding RNA (lncRNA) Neat1 and together with PABPN1 is required for normal paraspeckle function. We demonstrate that PABPN1 and MATR3 are required for paraspeckles, as well as for adenosine to inosine (A to I) RNA editing of Ctn RNA in muscle cells. We provide a functional link between PABPN1 and MATR3 through regulation of a common lncRNA target with downstream impact on paraspeckle morphology and function. We extend our analysis to a mouse model of OPMD and demonstrate altered paraspeckle morphology in the presence of endogenous levels of alanine-expanded PABPN1. In this study, we report protein-binding partners of PABPN1, which could provide insight into novel functions of PABPN1 in skeletal muscle and identify proteins that could be sequestered with alanine-expanded PABPN1 in the nuclear aggregates found in OPMD.
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Affiliation(s)
- Ayan Banerjee
- Department of Biology, Emory University, Atlanta, GA 30322, USA
| | - Katherine E Vest
- Department of Pharmacology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Grace K Pavlath
- Department of Pharmacology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Anita H Corbett
- Department of Biology, Emory University, Atlanta, GA 30322, USA
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17
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Vest KE, Phillips BL, Banerjee A, Apponi LH, Dammer EB, Xu W, Zheng D, Yu J, Tian B, Pavlath GK, Corbett AH. Novel mouse models of oculopharyngeal muscular dystrophy (OPMD) reveal early onset mitochondrial defects and suggest loss of PABPN1 may contribute to pathology. Hum Mol Genet 2017; 26:3235-3252. [PMID: 28575395 PMCID: PMC5886286 DOI: 10.1093/hmg/ddx206] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Revised: 05/14/2017] [Accepted: 05/23/2017] [Indexed: 01/09/2023] Open
Abstract
Oculopharyngeal muscular dystrophy (OPMD) is a late onset disease caused by polyalanine expansion in the poly(A) binding protein nuclear 1 (PABPN1). Several mouse models have been generated to study OPMD; however, most of these models have employed transgenic overexpression of alanine-expanded PABPN1. These models do not recapitulate the OPMD patient genotype and PABPN1 overexpression could confound molecular phenotypes. We have developed a knock-in mouse model of OPMD (Pabpn1+/A17) that contains one alanine-expanded Pabpn1 allele under the control of the native promoter and one wild-type Pabpn1 allele. This mouse is the closest available genocopy of OPMD patients. We show that Pabpn1+/A17 mice have a mild myopathic phenotype in adult and aged animals. We examined early molecular and biochemical phenotypes associated with expressing native levels of A17-PABPN1 and detected shorter poly(A) tails, modest changes in poly(A) signal (PAS) usage, and evidence of mitochondrial damage in these mice. Recent studies have suggested that a loss of PABPN1 function could contribute to muscle pathology in OPMD. To investigate a loss of function model of pathology, we generated a heterozygous Pabpn1 knock-out mouse model (Pabpn1+/Δ). Like the Pabpn1+/A17 mice, Pabpn1+/Δ mice have mild histologic defects, shorter poly(A) tails, and evidence of mitochondrial damage. However, the phenotypes detected in Pabpn1+/Δ mice only partially overlap with those detected in Pabpn1+/A17 mice. These results suggest that loss of PABPN1 function could contribute to but may not completely explain the pathology detected in Pabpn1+/A17 mice.
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Affiliation(s)
- Katherine E. Vest
- Department of Pharmacology, Emory University School of Medicine, Atlanta, GA, USA
- Department of Biology, Emory University, Atlanta, GA, USA
| | - Brittany L. Phillips
- Department of Pharmacology, Emory University School of Medicine, Atlanta, GA, USA
- Department of Biology, Emory University, Atlanta, GA, USA
| | - Ayan Banerjee
- Department of Biology, Emory University, Atlanta, GA, USA
| | - Luciano H. Apponi
- Department of Pharmacology, Emory University School of Medicine, Atlanta, GA, USA
| | - Eric B. Dammer
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA, USA
| | - Weiting Xu
- Department of Microbiology, Biochemistry, and Molecular Genetics, Rutgers New Jersey Medical School, Newark, NJ, USA
| | - Dinghai Zheng
- Department of Microbiology, Biochemistry, and Molecular Genetics, Rutgers New Jersey Medical School, Newark, NJ, USA
| | - Julia Yu
- Department of Biology, Emory University, Atlanta, GA, USA
| | - Bin Tian
- Department of Microbiology, Biochemistry, and Molecular Genetics, Rutgers New Jersey Medical School, Newark, NJ, USA
| | - Grace K. Pavlath
- Department of Pharmacology, Emory University School of Medicine, Atlanta, GA, USA
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18
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Malerba A, Klein P, Bachtarzi H, Jarmin SA, Cordova G, Ferry A, Strings V, Espinoza MP, Mamchaoui K, Blumen SC, St Guily JL, Mouly V, Graham M, Butler-Browne G, Suhy DA, Trollet C, Dickson G. PABPN1 gene therapy for oculopharyngeal muscular dystrophy. Nat Commun 2017; 8:14848. [PMID: 28361972 PMCID: PMC5380963 DOI: 10.1038/ncomms14848] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Accepted: 02/07/2017] [Indexed: 01/14/2023] Open
Abstract
Oculopharyngeal muscular dystrophy (OPMD) is an autosomal dominant, late-onset muscle disorder characterized by ptosis, swallowing difficulties, proximal limb weakness and nuclear aggregates in skeletal muscles. OPMD is caused by a trinucleotide repeat expansion in the PABPN1 gene that results in an N-terminal expanded polyalanine tract in polyA-binding protein nuclear 1 (PABPN1). Here we show that the treatment of a mouse model of OPMD with an adeno-associated virus-based gene therapy combining complete knockdown of endogenous PABPN1 and its replacement by a wild-type PABPN1 substantially reduces the amount of insoluble aggregates, decreases muscle fibrosis, reverts muscle strength to the level of healthy muscles and normalizes the muscle transcriptome. The efficacy of the combined treatment is further confirmed in cells derived from OPMD patients. These results pave the way towards a gene replacement approach for OPMD treatment. Oculopharyngeal muscular dystrophy is caused by trinucleotide repeat expansions in the PABPN1 gene. Here the authors use AAV-based gene therapy to knockdown the mutant gene and replace it with a wild-type allele, and show effectiveness in mice and in patient cells.
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Affiliation(s)
- A Malerba
- School of Biological Sciences, Royal Holloway, University of London, Egham Hill, Egham, TW20 0EX Surrey, UK
| | - P Klein
- Sorbonne Universités, UPMC Univ Paris 06, UM76, INSERM U974, Institut de Myologie, CNRS FRE3617, 47 bd de l'Hôpital, 75013 Paris, France
| | - H Bachtarzi
- School of Biological Sciences, Royal Holloway, University of London, Egham Hill, Egham, TW20 0EX Surrey, UK
| | - S A Jarmin
- School of Biological Sciences, Royal Holloway, University of London, Egham Hill, Egham, TW20 0EX Surrey, UK
| | - G Cordova
- Sorbonne Universités, UPMC Univ Paris 06, UM76, INSERM U974, Institut de Myologie, CNRS FRE3617, 47 bd de l'Hôpital, 75013 Paris, France
| | - A Ferry
- Sorbonne Universités, UPMC Univ Paris 06, UM76, INSERM U974, Institut de Myologie, CNRS FRE3617, 47 bd de l'Hôpital, 75013 Paris, France.,Sorbonne Paris Cité, Université Paris Descartes, 75006 Paris, France
| | - V Strings
- Benitec Biopharma, 3940 Trust Way, Hayward, California 94545, USA
| | - M Polay Espinoza
- Sorbonne Universités, UPMC Univ Paris 06, UM76, INSERM U974, Institut de Myologie, CNRS FRE3617, 47 bd de l'Hôpital, 75013 Paris, France
| | - K Mamchaoui
- Sorbonne Universités, UPMC Univ Paris 06, UM76, INSERM U974, Institut de Myologie, CNRS FRE3617, 47 bd de l'Hôpital, 75013 Paris, France
| | - S C Blumen
- Department of Neurology, Hillel Yaffe Medical Center, Hadera and Rappaport Faculty of Medicine, The Technion, 1 Efron Street, Haifa 31096, Israel
| | - J Lacau St Guily
- Sorbonne Universités, UPMC Univ Paris 06, UM76, INSERM U974, Institut de Myologie, CNRS FRE3617, 47 bd de l'Hôpital, 75013 Paris, France.,Department of Otolaryngology-Head and Neck Surgery, Faculty of Medicine and University Pierre-et-Marie-Curie, Paris VI, Tenon Hospital, Assistance Publique des Hopitaux de Paris, 75252 Paris, France
| | - V Mouly
- Sorbonne Universités, UPMC Univ Paris 06, UM76, INSERM U974, Institut de Myologie, CNRS FRE3617, 47 bd de l'Hôpital, 75013 Paris, France
| | - M Graham
- Benitec Biopharma, 3940 Trust Way, Hayward, California 94545, USA
| | - G Butler-Browne
- Sorbonne Universités, UPMC Univ Paris 06, UM76, INSERM U974, Institut de Myologie, CNRS FRE3617, 47 bd de l'Hôpital, 75013 Paris, France
| | - D A Suhy
- Benitec Biopharma, 3940 Trust Way, Hayward, California 94545, USA
| | - C Trollet
- Sorbonne Universités, UPMC Univ Paris 06, UM76, INSERM U974, Institut de Myologie, CNRS FRE3617, 47 bd de l'Hôpital, 75013 Paris, France
| | - G Dickson
- School of Biological Sciences, Royal Holloway, University of London, Egham Hill, Egham, TW20 0EX Surrey, UK
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19
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Klein P, Oloko M, Roth F, Montel V, Malerba A, Jarmin S, Gidaro T, Popplewell L, Perie S, Lacau St Guily J, de la Grange P, Antoniou MN, Dickson G, Butler-Browne G, Bastide B, Mouly V, Trollet C. Nuclear poly(A)-binding protein aggregates misplace a pre-mRNA outside of SC35 speckle causing its abnormal splicing. Nucleic Acids Res 2016; 44:10929-10945. [PMID: 27507886 PMCID: PMC5159528 DOI: 10.1093/nar/gkw703] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Revised: 07/25/2016] [Accepted: 07/29/2016] [Indexed: 11/21/2022] Open
Abstract
A short abnormal polyalanine expansion in the polyadenylate-binding protein nuclear-1 (PABPN1) protein causes oculopharyngeal muscular dystrophy (OPMD). Mutated PABPN1 proteins accumulate as insoluble intranuclear aggregates in muscles of OPMD patients. While the roles of PABPN1 in nuclear polyadenylation and regulation of alternative poly(A) site choice have been established, the molecular mechanisms which trigger pathological defects in OPMD and the role of aggregates remain to be determined. Using exon array, for the first time we have identified several splicing defects in OPMD. In particular, we have demonstrated a defect in the splicing regulation of the muscle-specific Troponin T3 (TNNT3) mutually exclusive exons 16 and 17 in OPMD samples compared to controls. This splicing defect is directly linked to the SC35 (SRSF2) splicing factor and to the presence of nuclear aggregates. As reported here, PABPN1 aggregates are able to trap TNNT3 pre-mRNA, driving it outside nuclear speckles, leading to an altered SC35-mediated splicing. This results in a decreased calcium sensitivity of muscle fibers, which could in turn plays a role in muscle pathology. We thus report a novel mechanism of alternative splicing deregulation that may play a role in various other diseases with nuclear inclusions or foci containing an RNA binding protein.
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Affiliation(s)
- Pierre Klein
- Sorbonne Universités, UPMC Univ Paris 06, Centre de Recherche en Myologie, INSERM UMRS974, CNRS FRE3617, Institut de Myologie, 47 bd de l'Hôpital, 75013 Paris, France
| | - Martine Oloko
- Sorbonne Universités, UPMC Univ Paris 06, Centre de Recherche en Myologie, INSERM UMRS974, CNRS FRE3617, Institut de Myologie, 47 bd de l'Hôpital, 75013 Paris, France
| | - Fanny Roth
- Sorbonne Universités, UPMC Univ Paris 06, Centre de Recherche en Myologie, INSERM UMRS974, CNRS FRE3617, Institut de Myologie, 47 bd de l'Hôpital, 75013 Paris, France
| | - Valérie Montel
- Univ. Lille - URePSSS - Unité de Recherche Pluridisciplinaire Sport Santé Société, équipe APMS, F-59000 Lille, France
| | - Alberto Malerba
- School of Biological Sciences, Royal Holloway - University of London, Egham, Surrey TW20 0EX, UK
| | - Susan Jarmin
- School of Biological Sciences, Royal Holloway - University of London, Egham, Surrey TW20 0EX, UK
| | - Teresa Gidaro
- Sorbonne Universités, UPMC Univ Paris 06, Centre de Recherche en Myologie, INSERM UMRS974, CNRS FRE3617, Institut de Myologie, 47 bd de l'Hôpital, 75013 Paris, France
| | - Linda Popplewell
- School of Biological Sciences, Royal Holloway - University of London, Egham, Surrey TW20 0EX, UK
| | - Sophie Perie
- Sorbonne Universités, UPMC Univ Paris 06, Centre de Recherche en Myologie, INSERM UMRS974, CNRS FRE3617, Institut de Myologie, 47 bd de l'Hôpital, 75013 Paris, France.,Department of Otolaryngology-Head and Neck Surgery, University Pierre-et-Marie-Curie, Paris VI, Tenon Hospital, Assistance Publique des Hopitaux de Paris, Paris, France
| | - Jean Lacau St Guily
- Sorbonne Universités, UPMC Univ Paris 06, Centre de Recherche en Myologie, INSERM UMRS974, CNRS FRE3617, Institut de Myologie, 47 bd de l'Hôpital, 75013 Paris, France.,Department of Otolaryngology-Head and Neck Surgery, University Pierre-et-Marie-Curie, Paris VI, Tenon Hospital, Assistance Publique des Hopitaux de Paris, Paris, France
| | | | - Michael N Antoniou
- King's College London School of Medicine, Gene Expression and Therapy Group, Department of Medical and Molecular Genetics, Guy's Hospital, London, UK
| | - George Dickson
- School of Biological Sciences, Royal Holloway - University of London, Egham, Surrey TW20 0EX, UK
| | - Gillian Butler-Browne
- Sorbonne Universités, UPMC Univ Paris 06, Centre de Recherche en Myologie, INSERM UMRS974, CNRS FRE3617, Institut de Myologie, 47 bd de l'Hôpital, 75013 Paris, France
| | - Bruno Bastide
- Univ. Lille - URePSSS - Unité de Recherche Pluridisciplinaire Sport Santé Société, équipe APMS, F-59000 Lille, France
| | - Vincent Mouly
- Sorbonne Universités, UPMC Univ Paris 06, Centre de Recherche en Myologie, INSERM UMRS974, CNRS FRE3617, Institut de Myologie, 47 bd de l'Hôpital, 75013 Paris, France
| | - Capucine Trollet
- Sorbonne Universités, UPMC Univ Paris 06, Centre de Recherche en Myologie, INSERM UMRS974, CNRS FRE3617, Institut de Myologie, 47 bd de l'Hôpital, 75013 Paris, France
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20
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Chou CC, Alexeeva OM, Yamada S, Pribadi A, Zhang Y, Mo B, Williams KR, Zarnescu DC, Rossoll W. PABPN1 suppresses TDP-43 toxicity in ALS disease models. Hum Mol Genet 2015; 24:5154-73. [PMID: 26130692 DOI: 10.1093/hmg/ddv238] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Accepted: 06/22/2015] [Indexed: 12/13/2022] Open
Abstract
TAR DNA-binding protein 43 (TDP-43) is a major disease protein in amyotrophic lateral sclerosis (ALS) and related neurodegenerative diseases. Both the cytoplasmic accumulation of toxic ubiquitinated and hyperphosphorylated TDP-43 fragments and the loss of normal TDP-43 from the nucleus may contribute to the disease progression by impairing normal RNA and protein homeostasis. Therefore, both the removal of pathological protein and the rescue of TDP-43 mislocalization may be critical for halting or reversing TDP-43 proteinopathies. Here, we report poly(A)-binding protein nuclear 1 (PABPN1) as a novel TDP-43 interaction partner that acts as a potent suppressor of TDP-43 toxicity. Overexpression of full-length PABPN1 but not a truncated version lacking the nuclear localization signal protects from pathogenic TDP-43-mediated toxicity, promotes the degradation of pathological TDP-43 and restores normal solubility and nuclear localization of endogenous TDP-43. Reduced levels of PABPN1 enhances the phenotypes in several cell culture and Drosophila models of ALS and results in the cytoplasmic mislocalization of TDP-43. Moreover, PABPN1 rescues the dysregulated stress granule (SG) dynamics and facilitates the removal of persistent SGs in TDP-43-mediated disease conditions. These findings demonstrate a role for PABPN1 in rescuing several cytopathological features of TDP-43 proteinopathy by increasing the turnover of pathologic proteins.
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Affiliation(s)
- Ching-Chieh Chou
- Department of Cell Biology, Center for Neurodegenerative Disease, Emory University School of Medicine, Atlanta, GA 30322, USA
| | | | - Shizuka Yamada
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, AZ 85721, USA and
| | - Amy Pribadi
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, AZ 85721, USA and
| | - Yi Zhang
- Department of Cell Biology, Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Bi Mo
- Department of Cell Biology
| | | | - Daniela C Zarnescu
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, AZ 85721, USA and
| | - Wilfried Rossoll
- Department of Cell Biology, Center for Neurodegenerative Disease, Emory University School of Medicine, Atlanta, GA 30322, USA,
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21
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Harish P, Malerba A, Dickson G, Bachtarzi H. Progress on gene therapy, cell therapy, and pharmacological strategies toward the treatment of oculopharyngeal muscular dystrophy. Hum Gene Ther 2015; 26:286-92. [PMID: 25860803 DOI: 10.1089/hum.2015.014] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Oculopharyngeal muscular dystrophy (OPMD) is a muscle-specific, late-onset degenerative disorder whereby muscles of the eyes (causing ptosis), throat (leading to dysphagia), and limbs (causing proximal limb weakness) are mostly affected. The disease is characterized by a mutation in the poly(A)-binding protein nuclear-1 (PABPN1) gene, resulting in a short GCG expansion in the polyalanine tract of PABPN1 protein. Accumulation of filamentous intranuclear inclusions in affected skeletal muscle cells constitutes the pathological hallmark of OPMD. This review highlights the current translational research advances in the treatment of OPMD. In vitro and in vivo disease models are described. Conventional and experimental therapeutic approaches are discussed with emphasis on novel molecular therapies including the use of intrabodies, gene therapy, and myoblast transfer therapy.
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Affiliation(s)
- Pradeep Harish
- 1School of Biological Sciences, Royal Holloway-University of London, Surrey, TW20 0EX, United Kingdom
| | - Alberto Malerba
- 1School of Biological Sciences, Royal Holloway-University of London, Surrey, TW20 0EX, United Kingdom
| | - George Dickson
- 1School of Biological Sciences, Royal Holloway-University of London, Surrey, TW20 0EX, United Kingdom
| | - Houria Bachtarzi
- 2Brighton Centre for Regenerative Medicine, School of Pharmacy and Biomolecular Sciences, University of Brighton, Brighton, BN2 4GJ, United Kingdom
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22
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Animal models in therapeutic drug discovery for oculopharyngeal muscular dystrophy. DRUG DISCOVERY TODAY. TECHNOLOGIES 2014; 10:e103-8. [PMID: 24050237 DOI: 10.1016/j.ddtec.2012.07.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Oculopharyngeal muscular dystrophy (OPMD) is a late onset disease which affects specific muscles. No pharmacological treatments are currently available for OPMD. In recent years, genetically tractable models of OPMD – Drosophila and Caenorhabditis elegans – have been generated. Although these models have not yet been used for large-scale primary drug screening, they have been very useful in candidate approaches for the identification of potential therapeutic compounds for OPMD. In this brief review, we summarize the data that validated active molecules for OPMD in animal models including Drosophila, C. elegans and mouse.
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23
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Vieira NM, Naslavsky MS, Licinio L, Kok F, Schlesinger D, Vainzof M, Sanchez N, Kitajima JP, Gal L, Cavaçana N, Serafini PR, Chuartzman S, Vasquez C, Mimbacas A, Nigro V, Pavanello RC, Schuldiner M, Kunkel LM, Zatz M. A defect in the RNA-processing protein HNRPDL causes limb-girdle muscular dystrophy 1G (LGMD1G). Hum Mol Genet 2014; 23:4103-10. [PMID: 24647604 DOI: 10.1093/hmg/ddu127] [Citation(s) in RCA: 81] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Limb-girdle muscular dystrophies (LGMD) are a heterogeneous group of genetically determined muscle disorders with a primary or predominant involvement of the pelvic or shoulder girdle musculature. More than 20 genes with autosomal recessive (LGMD2A to LGMD2Q) and autosomal dominant inheritance (LGMD1A to LGMD1H) have been mapped/identified to date. Mutations are known for six among the eight mapped autosomal dominant forms: LGMD1A (myotilin), LGMD1B (lamin A/C), LGMD1C (caveolin-3), LGMD1D (desmin), LGMD1E (DNAJB6), and more recently for LGMD1F (transportin-3). Our group previously mapped the LGMD1G gene at 4q21 in a Caucasian-Brazilian family. We now mapped a Uruguayan family with patients displaying a similar LGMD1G phenotype at the same locus. Whole genome sequencing identified, in both families, mutations in the HNRPDL gene. HNRPDL is a heterogeneous ribonucleoprotein family member, which participates in mRNA biogenesis and metabolism. Functional studies performed in S. cerevisiae showed that the loss of HRP1 (yeast orthologue) had pronounced effects on both protein levels and cell localizations, and yeast proteome revealed dramatic reorganization of proteins involved in RNA-processing pathways. In vivo analysis showed that hnrpdl is important for muscle development in zebrafish, causing a myopathic phenotype when knocked down. The present study presents a novel association between a muscular disorder and a RNA-related gene and reinforces the importance of RNA binding/processing proteins in muscle development and muscle disease. Understanding the role of these proteins in muscle might open new therapeutic approaches for muscular dystrophies.
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Affiliation(s)
- Natássia M Vieira
- Human Genome and Stem Cell Center, Biosciences Institute, University of São Paulo, São Paulo, Brazil Program in Genomics, Department of Pediatrics and The Manton Center for Orphan Disease Research, Children's Hospital Boston, Boston, MA, USA Department of Genetics, Harvard Medical School, Boston, MA, USA
| | - Michel S Naslavsky
- Human Genome and Stem Cell Center, Biosciences Institute, University of São Paulo, São Paulo, Brazil
| | - Luciana Licinio
- Human Genome and Stem Cell Center, Biosciences Institute, University of São Paulo, São Paulo, Brazil
| | - Fernando Kok
- Human Genome and Stem Cell Center, Biosciences Institute, University of São Paulo, São Paulo, Brazil Department of Neurology, University of São Paulo Medical School, São Paulo, Brazil Mendelics Análise Genômica, São Paulo, Brazil
| | - David Schlesinger
- Human Genome and Stem Cell Center, Biosciences Institute, University of São Paulo, São Paulo, Brazil Mendelics Análise Genômica, São Paulo, Brazil Hospital Israelita Albert Einstein, São Paulo, Brazil
| | - Mariz Vainzof
- Human Genome and Stem Cell Center, Biosciences Institute, University of São Paulo, São Paulo, Brazil
| | - Nury Sanchez
- Hospital de Clínicas, Montevideu, Montevideo, Uruguay
| | - João Paulo Kitajima
- Human Genome and Stem Cell Center, Biosciences Institute, University of São Paulo, São Paulo, Brazil Mendelics Análise Genômica, São Paulo, Brazil
| | - Lihi Gal
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Natale Cavaçana
- Human Genome and Stem Cell Center, Biosciences Institute, University of São Paulo, São Paulo, Brazil
| | - Peter R Serafini
- Program in Genomics, Department of Pediatrics and The Manton Center for Orphan Disease Research, Children's Hospital Boston, Boston, MA, USA Department of Genetics, Harvard Medical School, Boston, MA, USA
| | - Silvia Chuartzman
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | | | - Adriana Mimbacas
- Department of Genetics, Clemente Estabele Institute, Montevideo, Uruguay
| | - Vincenzo Nigro
- TIGEM (Telethon Institute of Genetics and Medicine), Napoli, Italy
| | - Rita C Pavanello
- Human Genome and Stem Cell Center, Biosciences Institute, University of São Paulo, São Paulo, Brazil
| | - Maya Schuldiner
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Louis M Kunkel
- Program in Genomics, Department of Pediatrics and The Manton Center for Orphan Disease Research, Children's Hospital Boston, Boston, MA, USA Department of Genetics, Harvard Medical School, Boston, MA, USA
| | - Mayana Zatz
- Human Genome and Stem Cell Center, Biosciences Institute, University of São Paulo, São Paulo, Brazil
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Banerjee A, Apponi LH, Pavlath GK, Corbett AH. PABPN1: molecular function and muscle disease. FEBS J 2013; 280:4230-50. [PMID: 23601051 DOI: 10.1111/febs.12294] [Citation(s) in RCA: 80] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2013] [Revised: 04/03/2013] [Accepted: 04/11/2013] [Indexed: 12/17/2022]
Abstract
The polyadenosine RNA binding protein polyadenylate-binding nuclear protein 1 (PABPN1) plays key roles in post-transcriptional processing of RNA. Although PABPN1 is ubiquitously expressed and presumably contributes to control of gene expression in all tissues, mutation of the PABPN1 gene causes the disease oculopharyngeal muscular dystrophy (OPMD), in which a limited set of skeletal muscles are affected. A major goal in the field of OPMD research is to understand why mutation of a ubiquitously expressed gene leads to a muscle-specific disease. PABPN1 plays a well-documented role in controlling the poly(A) tail length of RNA transcripts but new functions are emerging through studies that exploit a variety of unbiased screens as well as model organisms. This review addresses (a) the molecular function of PABPN1 incorporating recent findings that reveal novel cellular functions for PABPN1 and (b) the approaches that are being used to understand the molecular defects that stem from expression of mutant PABPN1. The long-term goal in this field of research is to understand the key molecular functions of PABPN1 in muscle as well as the mechanisms that underlie the pathological consequences of mutant PABPN1. Armed with this information, researchers can seek to develop therapeutic approaches to enhance the quality of life for patients afflicted with OPMD.
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Affiliation(s)
- Ayan Banerjee
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322, USA
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25
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Hanson KA, Kim SH, Tibbetts RS. RNA-binding proteins in neurodegenerative disease: TDP-43 and beyond. WILEY INTERDISCIPLINARY REVIEWS-RNA 2011; 3:265-85. [PMID: 22028183 DOI: 10.1002/wrna.111] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Neurodegenerative diseases are a diverse group of disorders that affect different neuron populations, differ in onset and severity, and can be either inherited or sporadic. One common pathological feature of most of these diseases is the presence of insoluble inclusions in and around neurons, which largely consist of misfolded and aggregated protein. For this reason, neurodegenerative diseases are typically thought to be disorders of aberrant protein processing, in which the cumulative effects of misfolded protein aggregates overwhelm the neuron's proteostatic capacity. However, a growing body of evidence suggests a role for abnormal RNA processing in neurodegenerative disease. The importance of RNA metabolism in disease was highlighted by the discovery of TDP-43 (TAR DNA-binding protein of 43 kDa), an RNA-binding protein (RBP), as a primary component of insoluble aggregates in patients with sporadic amyotrophic lateral sclerosis (ALS). Subsequently, inherited mutations in TDP-43 and the structurally related RBP, FUS/TLS (fused in sarcoma/translated in liposarcoma), were found to cause ALS. These exciting findings have ushered in a new era of ALS research in which the deregulation of RNA metabolism is viewed as a central cause of motor neuron deterioration. In addition, the fact that neuropathologically and anatomically distinct neurodegenerative diseases display altered RNA metabolism suggests that common pathologic mechanisms may underlie many of these disorders.
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Affiliation(s)
- Keith A Hanson
- Department of Human Oncology, University of Wisconsin-Madison, Madison, WI, USA
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26
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Anthony K, Gallo JM. Aberrant RNA processing events in neurological disorders. Brain Res 2010; 1338:67-77. [DOI: 10.1016/j.brainres.2010.03.008] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2010] [Revised: 02/24/2010] [Accepted: 03/03/2010] [Indexed: 12/12/2022]
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Trollet C, Anvar SY, Venema A, Hargreaves IP, Foster K, Vignaud A, Ferry A, Negroni E, Hourde C, Baraibar MA, 't Hoen PAC, Davies JE, Rubinsztein DC, Heales SJ, Mouly V, van der Maarel SM, Butler-Browne G, Raz V, Dickson G. Molecular and phenotypic characterization of a mouse model of oculopharyngeal muscular dystrophy reveals severe muscular atrophy restricted to fast glycolytic fibres. Hum Mol Genet 2010; 19:2191-207. [PMID: 20207626 DOI: 10.1093/hmg/ddq098] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Oculopharyngeal muscular dystrophy (OPMD) is an adult-onset disorder characterized by ptosis, dysphagia and proximal limb weakness. Autosomal-dominant OPMD is caused by a short (GCG)(8-13) expansions within the first exon of the poly(A)-binding protein nuclear 1 gene (PABPN1), leading to an expanded polyalanine tract in the mutated protein. Expanded PABPN1 forms insoluble aggregates in the nuclei of skeletal muscle fibres. In order to gain insight into the different physiological processes affected in OPMD muscles, we have used a transgenic mouse model of OPMD (A17.1) and performed transcriptomic studies combined with a detailed phenotypic characterization of this model at three time points. The transcriptomic analysis revealed a massive gene deregulation in the A17.1 mice, among which we identified a significant deregulation of pathways associated with muscle atrophy. Using a mathematical model for progression, we have identified that one-third of the progressive genes were also associated with muscle atrophy. Functional and histological analysis of the skeletal muscle of this mouse model confirmed a severe and progressive muscular atrophy associated with a reduction in muscle strength. Moreover, muscle atrophy in the A17.1 mice was restricted to fast glycolytic fibres, containing a large number of intranuclear inclusions (INIs). The soleus muscle and, in particular, oxidative fibres were spared, even though they contained INIs albeit to a lesser degree. These results demonstrate a fibre-type specificity of muscle atrophy in this OPMD model. This study improves our understanding of the biological pathways modified in OPMD to identify potential biomarkers and new therapeutic targets.
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Draper I, Tabaka ME, Jackson FR, Salomon RN, Kopin AS. The evolutionarily conserved RNA binding protein SMOOTH is essential for maintaining normal muscle function. Fly (Austin) 2009; 3:235-46. [PMID: 19755840 DOI: 10.4161/fly.9517] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The Drosophila smooth gene encodes an RNA binding protein that has been well conserved through evolution. To investigate the pleiotropic functions mediated by the smooth gene, we have selected and characterized two sm mutants, which are viable as adults yet display robust phenotypes (including a significant decrease in lifespan). Utilizing these mutants, we have made the novel observation that disruption of the smooth/CG9218 locus leads to age-dependent muscle degeneration, and motor dysfunction. Histological characterization of adult sm mutants revealed marked abnormalities in the major thoracic tubular muscle: the tergal depressor of the trochanter (TDT). Corresponding defects include extensive loss/disruption of striations and nuclei. These pathological changes are recapitulated in flies that express a smooth RNA interference construct (sm RNAi) in the mesoderm. In contrast, targeting sm RNAi constructs to motor neurons does not alter muscle morphology. In addition to examining the TDT phenotype, we explored whether other muscular abnormalities were evident. Utilizing physiological assays developed in the laboratory, we have found that the thoracic muscle defect is preceded by dysmotility of the gastrointestinal tract. SMOOTH thus joins a growing list of hnRNPs that have previously been linked to muscle physiology/pathophysiology. Our findings in Drosophila set the stage for investigating the role of the corresponding mammalian homolog, hnRNP L, in muscle function.
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Affiliation(s)
- Isabelle Draper
- Molecular Cardiology Research Institute, Tufts Medical Center, Boston, MA, USA.
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29
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Messaed C, Rouleau G. Molecular mechanisms underlying polyalanine diseases. Neurobiol Dis 2009; 34:397-405. [DOI: 10.1016/j.nbd.2009.02.013] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2008] [Revised: 02/12/2009] [Accepted: 02/16/2009] [Indexed: 10/21/2022] Open
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Chartier A, Raz V, Sterrenburg E, Verrips CT, van der Maarel SM, Simonelig M. Prevention of oculopharyngeal muscular dystrophy by muscular expression of Llama single-chain intrabodies in vivo. Hum Mol Genet 2009; 18:1849-59. [DOI: 10.1093/hmg/ddp101] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
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31
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Toriumi K, Oma Y, Kino Y, Futai E, Sasagawa N, Ishiura S. Expression of polyalanine stretches induces mitochondrial dysfunction. J Neurosci Res 2008; 86:1529-37. [PMID: 18214990 DOI: 10.1002/jnr.21619] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
In recent years, several novel types of disorders have been characterized, including what have been termed polyalanine diseases, in which patients have expanded triplet repeats in specific genes, resulting in the translation of aberrantly elongated polyalanine stretches. In this study, we showed that yellow fluorescent protein (YFP)-fused elongated polyalanine stretches localized exclusively to the cytoplasm and formed aggregates. Additionally, the polyalanine stretches themselves were toxic. We sought to identify proteins that bound directly to the polyalanine stretches, as factors that might be involved in triggering cell death. Many mitochondrial proteins were identified as polyalanine-binding proteins. We showed that one of the identified proteins, succinate dehydrogenase subunit A, was decreased in the mitochondria of cells expressing polyalanine stretches; as a result, succinate oxidative activity was decreased. Furthermore, the polyalanine stretches also associated directly with mitochondria. This suggests that polya-lanine stretches might directly induce cell death. Additionally, the mitochondrial membrane potential was reduced in cells expressing polyalanine stretches. We propose a novel mechanism by which polyalanine stretches may cause cytotoxicity through mitochondrial dysfunction. This may be a common mechanism underlying the pathogenesis of all polyalanine diseases.
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Affiliation(s)
- Kazuya Toriumi
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Meguro-ku, Tokyo, Japan
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32
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Villagra NT, Bengoechea R, Vaqué JP, Llorca J, Berciano MT, Lafarga M. Nuclear compartmentalization and dynamics of the poly(A)-binding protein nuclear 1 (PABPN1) inclusions in supraoptic neurons under physiological and osmotic stress conditions. Mol Cell Neurosci 2008; 37:622-33. [DOI: 10.1016/j.mcn.2007.12.012] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2007] [Revised: 11/14/2007] [Accepted: 12/06/2007] [Indexed: 11/26/2022] Open
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Abu-Baker A, Rouleau GA. Oculopharyngeal muscular dystrophy: Recent advances in the understanding of the molecular pathogenic mechanisms and treatment strategies. Biochim Biophys Acta Mol Basis Dis 2007; 1772:173-85. [PMID: 17110089 DOI: 10.1016/j.bbadis.2006.10.003] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2006] [Revised: 10/05/2006] [Accepted: 10/06/2006] [Indexed: 12/24/2022]
Abstract
Oculopharyngeal muscular dystrophy (OPMD) is an adult-onset disorder characterized by progressive eyelid drooping, swallowing difficulties and proximal limb weakness. OPMD is caused by a small expansion of a short polyalanine tract in the poly (A) binding protein nuclear 1 protein (PABPN1). The mechanism by which the polyalanine expansion mutation in PABPN1 causes disease is unclear. PABPN1 is a nuclear multi-functional protein which is involved in pre-mRNA polyadenylation, transcription regulation, and mRNA nucleocytoplasmic transport. The distinct pathological hallmark of OPMD is the presence of filamentous intranuclear inclusions (INIs) in patient's skeletal muscle cells. The exact relationship between mutant PABPN1 intranuclear aggregates and pathology is not clear. OPMD is a unique disease sharing common pathogenic features with other polyalanine disorders, as well as with polyglutamine and dystrophic disorders. This chapter aims to review the rapidly growing body of knowledge concerning OPMD. First, we outline the background of OPMD. Second, we compare OPMD with other trinucleotide repeat disorders. Third, we discuss the recent advances in the understanding of the molecular mechanisms underlying OPMD pathogenesis. Finally, we review recent therapeutic strategies for OPMD.
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Affiliation(s)
- Aida Abu-Baker
- Center for the Study of Brain Diseases, CHUM Research Center-Notre Dame Hospital, J.A. de Sève Pavillion, Room Y-3633, 1560, Sherbrooke Street East, Montreal, QC, Canada H2L 4M1
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Marie-Josée Sasseville A, Caron AW, Bourget L, Klein AF, Dicaire MJ, Rouleau GA, Massie B, Langelier Y, Brais B. The dynamism of PABPN1 nuclear inclusions during the cell cycle. Neurobiol Dis 2006; 23:621-9. [PMID: 16860991 DOI: 10.1016/j.nbd.2006.05.015] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2006] [Revised: 05/09/2006] [Accepted: 05/18/2006] [Indexed: 11/30/2022] Open
Abstract
Oculopharyngeal muscular dystrophy (OPMD) is caused by expansion of a (GCN)10 to a (GCN)11-17 repeat coding for a polyalanine domain at the N-terminal part of poly(A) binding protein nuclear 1 (PABPN1). OPMD is characterized by the presence of intranuclear inclusions (INIs) in skeletal muscle fibers of patients. The formation of GFP-b13AlaPABPN1 INIs and their fate through the cell cycle were followed by time-lapse imaging. Our observations demonstrated that the GFP-b13AlaPABPN1 INIs are dynamic structures that can disassemble during mitosis. However, their presence in cells occasionally led to apoptosis. The length of the polyalanine tail or the overexpression of PABPN1 did not significantly affect the percentage of soluble PABPN1 in vitro. Moreover, overexpression of either the wild type (wt) or mutant (mut) forms of PABPN1 slowed down the cell proliferation. The slowing down of proliferation together with the occasional occurrence of apoptosis could contribute in vivo to the late onset of this disease.
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Affiliation(s)
- A Marie-Josée Sasseville
- Laboratoire de Neurogénétique, Centre de Recherche du CHUM, Université de Montréal, Montréal, Québec, Canada H2L 4M1
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36
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Chartier A, Benoit B, Simonelig M. A Drosophila model of oculopharyngeal muscular dystrophy reveals intrinsic toxicity of PABPN1. EMBO J 2006; 25:2253-62. [PMID: 16642034 PMCID: PMC1462976 DOI: 10.1038/sj.emboj.7601117] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2005] [Accepted: 04/04/2006] [Indexed: 11/09/2022] Open
Abstract
Oculopharyngeal muscular dystrophy (OPMD) is an adult-onset syndrome characterized by progressive degeneration of particular muscles. OPMD is caused by short GCG repeat expansions within the gene encoding the nuclear poly(A)-binding protein 1 (PABPN1) that extend an N-terminal polyalanine tract in the protein. Mutant PABPN1 aggregates as nuclear inclusions in OMPD patient muscles. We have created a Drosophila model of OPMD that recapitulates the features of the human disorder: progressive muscle degeneration, with muscle defects proportional to the number of alanines in the tract, and formation of PABPN1 nuclear inclusions. Strikingly, the polyalanine tract is not absolutely required for muscle degeneration, whereas another domain of PABPN1, the RNA-binding domain and its function in RNA binding are required. This demonstrates that OPMD does not result from polyalanine toxicity, but from an intrinsic property of PABPN1. We also identify several suppressors of the OPMD phenotype. This establishes our OPMD Drosophila model as a powerful in vivo test to understand the disease process and develop novel therapeutic strategies.
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Affiliation(s)
- Aymeric Chartier
- Génétique du Développement de la Drosophile, Institut de Génétique Humaine, CNRS UPR 1142, Montpellier Cedex 5, France
| | - Béatrice Benoit
- Génétique du Développement de la Drosophile, Institut de Génétique Humaine, CNRS UPR 1142, Montpellier Cedex 5, France
| | - Martine Simonelig
- Génétique du Développement de la Drosophile, Institut de Génétique Humaine, CNRS UPR 1142, Montpellier Cedex 5, France
- Génétique du Développement de la Drosophile, Institut de Génétique Humaine, 141 rue de la Cardonille, CNRS UPR 1142, 34396 Montpellier Cedex 5, France. Tel.: +33 4 99 61 99 59; Fax: +33 4 99 61 99 57; E-mail:
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Verheesen P, de Kluijver A, van Koningsbruggen S, de Brij M, de Haard HJ, van Ommen GJB, van der Maarel SM, Verrips CT. Prevention of oculopharyngeal muscular dystrophy-associated aggregation of nuclear poly(A)-binding protein with a single-domain intracellular antibody. Hum Mol Genet 2005; 15:105-11. [PMID: 16319127 DOI: 10.1093/hmg/ddi432] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Oculopharyngeal muscular dystrophy (OPMD) belongs to the group of protein aggregation disorders and is caused by extensions of the N-terminal polyalanine stretch of the nuclear polyA-binding protein 1 (PABPN1). The presence of PABPN1-containing intranuclear aggregates in skeletal muscle is unique for OPMD and is also observed in transgenic mouse and cell models for OPMD. These models consistently support a direct role for the protein aggregation in OPMD pathogenesis. We have isolated and characterized a diverse panel of single-domain antibody reagents (VHH), recognizing different epitopes in PABPN1. The antibody reagents specifically detect endogenous PABPN1 in cell lysates on western blot and label PABPN1 in cultured cells and muscle sections. When expressed intracellularly as intrabodies in a cellular model for OPMD, aggregation of PABPN1 was prevented in a dose-dependent manner. More importantly yet, these intrabodies could also reduce the presence of already existing aggregates. Given the domain specificity of VHH-mediated aggregation interference, this approach at least allows the definition of the nucleation kernel in aggregation-prone proteins, thus facilitating etiological insight into this and other protein aggregation disorders, and ultimately, it may well provide useful therapeutic agents.
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Affiliation(s)
- Peter Verheesen
- Department of Molecular and Cellular Biology, University of Utrecht, The Netherlands.
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Abu-Baker A, Laganiere S, Fan X, Laganiere J, Brais B, Rouleau GA. Cytoplasmic targeting of mutant poly(A)-binding protein nuclear 1 suppresses protein aggregation and toxicity in oculopharyngeal muscular dystrophy. Traffic 2005; 6:766-79. [PMID: 16101680 DOI: 10.1111/j.1600-0854.2005.00315.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Oculopharyngeal muscular dystrophy (OPMD) is an adult-onset disorder characterized by progressive eyelid drooping, swallowing difficulties and proximal limb weakness. The autosomal dominant form of this disease is caused by a polyalanine expansion from 10 to 12-17 residues, located at the N-terminus of the poly(A)-binding protein nuclear 1 (PABPN1). A distinct pathological hallmark of OPMD is the presence of filamentous intranuclear aggregates in patients' skeletal muscle cells. Wildtype PABPN1 protein is expressed ubiquitously and was shown to be mostly concentrated in discrete nuclear domains called 'speckles'. Using an established cell- culture model, we show that most mutant PABPN1- positive (alanine expanded form) intranuclear aggregates are structures distinct from intranuclear speckles. In contrast, the promyelocytic leukaemia protein, a major component of nuclear bodies, strongly colocalized to intranuclear aggregates of mutant PABPN1. Wildtype PABPN1 can freely shuttle between the nucleus and cytoplasm. We determined whether the nuclear environment is necessary for mutant PABPN1 inclusion formation and cellular toxicity. This was achieved by inactivating the mutant PABPN1 nuclear localization signal and by generating full-length mutant PABPN1 fused to a strong nuclear export sequence. A green fluorescence protein tag inserted at the N-terminus of both wildtype PABPN1 (ala10) and mutant PABPN1 (ala17) proteins allowed us to visualize their subcellular localization. Targeting mutant PABPN1 to the cytoplasm resulted in a significant suppression of both intranuclear aggregates formation and cellular toxicity, two histological consequences of OPMD. Our results indicate that the nuclear localization of mutant PABPN1 is crucial to OPMD pathogenesis.
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Affiliation(s)
- Aida Abu-Baker
- Center for Research in Neuroscience, McGill University, and the McGill University Health Center, 1650 Cedar Avenue, Montreal, Quebec, Canada H3G 1A4
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Escudié L, Payen JL, Thiry-Escudié I, Carreiro M, Trémelet L, Seigneuric C. Dystrophie musculaire oculopharyngée révélée par une dysphagie. Rev Med Interne 2005; 26:759-62. [PMID: 16023269 DOI: 10.1016/j.revmed.2005.05.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2005] [Accepted: 05/16/2005] [Indexed: 11/19/2022]
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Corbeil-Girard LP, Klein AF, Sasseville AMJ, Lavoie H, Dicaire MJ, Saint-Denis A, Pagé M, Duranceau A, Codère F, Bouchard JP, Karpati G, Rouleau GA, Massie B, Langelier Y, Brais B. PABPN1 overexpression leads to upregulation of genes encoding nuclear proteins that are sequestered in oculopharyngeal muscular dystrophy nuclear inclusions. Neurobiol Dis 2005; 18:551-67. [PMID: 15755682 DOI: 10.1016/j.nbd.2004.10.019] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2004] [Revised: 09/14/2004] [Accepted: 10/13/2004] [Indexed: 10/25/2022] Open
Abstract
Oculopharyngeal muscular dystrophy (OPMD) is an adult-onset disease caused by expanded (GCN)12-17 stretches encoding the N-terminal polyalanine domain of the poly(A) binding protein nuclear 1 (PABPN1). OPMD is characterized by intranuclear inclusions (INIs) in skeletal muscle fibers, which contain PABPN1, molecular chaperones, ubiquitin, proteasome subunits, and poly(A)-mRNA. We describe an adenoviral model of PABPN1 expression that produces INIs in most cells. Microarray analysis revealed that PABPN1 overexpression reproducibly changed the expression of 202 genes. Sixty percent of upregulated genes encode nuclear proteins, including many RNA and DNA binding proteins. Immunofluorescence microscopy revealed that all tested nuclear proteins encoded by eight upregulated genes colocalize with PABPN1 within the INIs: CUGBP1, SFRS3, FKBP1A, HMG2, HNRPA1, PRC1, S100P, and HSP70. In addition, CUGBP1, SFRS3, and FKBP1A were also found in OPMD muscle INIs. This study demonstrates that a large number of nuclear proteins are sequestered in OPMD INIs, which may compromise cellular function.
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Affiliation(s)
- Louis-Philippe Corbeil-Girard
- Laboratoire de Neurogénétique, Centre de Recherche du CHUM, Université de Montréal, Montréal, Québec, Canada H2L 4M1
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Wirtschafter JD, Ferrington DA, McLoon LK. Continuous Remodeling of Adult Extraocular Muscles as an Explanation for Selective Craniofacial Vulnerability in Oculopharyngeal Muscular Dystrophy. J Neuroophthalmol 2004; 24:62-7. [PMID: 15206442 DOI: 10.1097/00041327-200403000-00013] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Oculopharyngeal muscular mystrophy (OPMD) is an inherited disorder caused by mutations of the polyadenylate binding protein nuclear 1 (PABPN1) gene. While a pathogenic hypothesis has been formulated that links the genetic and molecular abnormalities to cellular abnormalities, there is no proven explanation for the targeting of the craniofacial muscles. We propose a hypothesis that bridges this gap. It is based on the phenomenon of continuous remodeling of normal adult extraocular muscles (EOMs). Unlike the EOMs, the myonuclei of other skeletal muscles are postmitotic in the adult unless the muscles are injured. Continuous myofiber remodeling most likely requires upregulation of genes involved in cell cycling, and in protein degradation and synthesis. PABPN1 is a nuclear protein that performs the essential function of controlling polyadenylation of mRNA and the fidelity of protein synthesis. In OPMD, the ongoing production of mutant PABPN1 in muscles undergoing continuous remodeling could result in a failure of accurate production of mRNA required for the maintenance of the myocytes. Over many years, this would lead to cumulative myonuclear loss and finally to myofiber loss. This hypothesis offers an explanation for the selective involvement of extraocular muscles affected in OPMD and the onset of symptoms in adulthood.
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Affiliation(s)
- Jonathan D Wirtschafter
- Department of Ophthalmology, University of Minnesota Medical School, Room 374 LRB, 2001 6th Street SE, Minneapolis, MN 55455, USA
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