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Han X, Xing L, Hong Y, Zhang X, Hao B, Lu JY, Huang M, Wang Z, Ma S, Zhan G, Li T, Hao X, Tao Y, Li G, Zhou S, Zheng Z, Shao W, Zeng Y, Ma D, Zhang W, Xie Z, Deng H, Yan J, Deng W, Shen X. Nuclear RNA homeostasis promotes systems-level coordination of cell fate and senescence. Cell Stem Cell 2024; 31:694-716.e11. [PMID: 38631356 DOI: 10.1016/j.stem.2024.03.015] [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: 09/22/2023] [Revised: 02/01/2024] [Accepted: 03/26/2024] [Indexed: 04/19/2024]
Abstract
Understanding cellular coordination remains a challenge despite knowledge of individual pathways. The RNA exosome, targeting a wide range of RNA substrates, is often downregulated in cellular senescence. Utilizing an auxin-inducible system, we observed that RNA exosome depletion in embryonic stem cells significantly affects the transcriptome and proteome, causing pluripotency loss and pre-senescence onset. Mechanistically, exosome depletion triggers acute nuclear RNA aggregation, disrupting nuclear RNA-protein equilibrium. This disturbance limits nuclear protein availability and hinders polymerase initiation and engagement, reducing gene transcription. Concurrently, it promptly disrupts nucleolar transcription, ribosomal processes, and nuclear exporting, resulting in a translational shutdown. Prolonged exosome depletion induces nuclear structural changes resembling senescent cells, including aberrant chromatin compaction, chromocenter disassembly, and intensified heterochromatic foci. These effects suggest that the dynamic turnover of nuclear RNA orchestrates crosstalk between essential processes to optimize cellular function. Disruptions in nuclear RNA homeostasis result in systemic functional decline, altering the cell state and promoting senescence.
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Affiliation(s)
- Xue Han
- State Key Laboratory of Membrane Biology, Beijing Frontier Research Center for Biological Structure, Tsinghua-Peking Joint Center for Life Sciences, School of Basic Medical Sciences, Tsinghua University, Beijing 100084, China
| | - Linqing Xing
- State Key Laboratory of Membrane Biology, Beijing Frontier Research Center for Biological Structure, Tsinghua-Peking Joint Center for Life Sciences, School of Basic Medical Sciences, Tsinghua University, Beijing 100084, China
| | - Yantao Hong
- State Key Laboratory of Membrane Biology, Beijing Frontier Research Center for Biological Structure, Tsinghua-Peking Joint Center for Life Sciences, School of Basic Medical Sciences, Tsinghua University, Beijing 100084, China
| | - Xuechun Zhang
- State Key Laboratory of Membrane Biology, Beijing Frontier Research Center for Biological Structure, Tsinghua-Peking Joint Center for Life Sciences, School of Basic Medical Sciences, Tsinghua University, Beijing 100084, China
| | - Bo Hao
- SXMU-Tsinghua Collaborative Innovation Center for Frontier Medicine, Shanxi Medical University, Taiyuan, Shanxi 030001, China
| | - J Yuyang Lu
- State Key Laboratory of Membrane Biology, Beijing Frontier Research Center for Biological Structure, Tsinghua-Peking Joint Center for Life Sciences, School of Basic Medical Sciences, Tsinghua University, Beijing 100084, China
| | - Mengyuan Huang
- State Key Laboratory of Membrane Biology, Beijing Frontier Research Center for Biological Structure, Tsinghua-Peking Joint Center for Life Sciences, School of Basic Medical Sciences, Tsinghua University, Beijing 100084, China
| | - Zuhui Wang
- Biomedical Pioneering Innovation Center (BIOPIC), Beijing Advanced Innovation Center for Genomics (ICG), Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
| | - Shaoqian Ma
- State Key Laboratory of Membrane Biology, Beijing Frontier Research Center for Biological Structure, Tsinghua-Peking Joint Center for Life Sciences, School of Basic Medical Sciences, Tsinghua University, Beijing 100084, China
| | - Ge Zhan
- State Key Laboratory of Membrane Biology, Beijing Frontier Research Center for Biological Structure, Tsinghua-Peking Joint Center for Life Sciences, School of Basic Medical Sciences, Tsinghua University, Beijing 100084, China
| | - Tong Li
- State Key Laboratory of Membrane Biology, Beijing Frontier Research Center for Biological Structure, Tsinghua-Peking Joint Center for Life Sciences, School of Basic Medical Sciences, Tsinghua University, Beijing 100084, China
| | - Xiaowen Hao
- State Key Laboratory of Membrane Biology, Beijing Frontier Research Center for Biological Structure, Tsinghua-Peking Joint Center for Life Sciences, School of Basic Medical Sciences, Tsinghua University, Beijing 100084, China
| | - Yibing Tao
- State Key Laboratory of Membrane Biology, Beijing Frontier Research Center for Biological Structure, Tsinghua-Peking Joint Center for Life Sciences, School of Basic Medical Sciences, Tsinghua University, Beijing 100084, China
| | - Guanwen Li
- State Key Laboratory of Membrane Biology, Beijing Frontier Research Center for Biological Structure, Tsinghua-Peking Joint Center for Life Sciences, School of Basic Medical Sciences, Tsinghua University, Beijing 100084, China
| | - Shuqin Zhou
- State Key Laboratory of Membrane Biology, Beijing Frontier Research Center for Biological Structure, Tsinghua-Peking Joint Center for Life Sciences, School of Basic Medical Sciences, Tsinghua University, Beijing 100084, China
| | - Zheng Zheng
- State Key Laboratory of Membrane Biology, Beijing Frontier Research Center for Biological Structure, Tsinghua-Peking Joint Center for Life Sciences, School of Basic Medical Sciences, Tsinghua University, Beijing 100084, China
| | - Wen Shao
- State Key Laboratory of Membrane Biology, Beijing Frontier Research Center for Biological Structure, Tsinghua-Peking Joint Center for Life Sciences, School of Basic Medical Sciences, Tsinghua University, Beijing 100084, China
| | - Yitian Zeng
- State Key Laboratory of Membrane Biology, Beijing Frontier Research Center for Biological Structure, Tsinghua-Peking Joint Center for Life Sciences, School of Basic Medical Sciences, Tsinghua University, Beijing 100084, China
| | - Dacheng Ma
- MOE Key Laboratory of Bioinformatics and Bioinformatics Division, Center for Synthetic and Systems Biology, Department of Automation, Beijing National Research Center for Information Science and Technology, Tsinghua University, Beijing 100084, China
| | - Wenhao Zhang
- MOE Key Laboratory of Bioinformatics, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Zhen Xie
- MOE Key Laboratory of Bioinformatics and Bioinformatics Division, Center for Synthetic and Systems Biology, Department of Automation, Beijing National Research Center for Information Science and Technology, Tsinghua University, Beijing 100084, China
| | - Haiteng Deng
- MOE Key Laboratory of Bioinformatics, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Jiangwei Yan
- SXMU-Tsinghua Collaborative Innovation Center for Frontier Medicine, Shanxi Medical University, Taiyuan, Shanxi 030001, China
| | - Wulan Deng
- Biomedical Pioneering Innovation Center (BIOPIC), Beijing Advanced Innovation Center for Genomics (ICG), Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
| | - Xiaohua Shen
- State Key Laboratory of Membrane Biology, Beijing Frontier Research Center for Biological Structure, Tsinghua-Peking Joint Center for Life Sciences, School of Basic Medical Sciences, Tsinghua University, Beijing 100084, China; SXMU-Tsinghua Collaborative Innovation Center for Frontier Medicine, Shanxi Medical University, Taiyuan, Shanxi 030001, China.
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2
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Guan WL, Jiang LL, Yin XF, Hu HY. PABPN1 aggregation is driven by Ala expansion and poly(A)-RNA binding, leading to CFIm25 sequestration that impairs alternative polyadenylation. J Biol Chem 2023; 299:105019. [PMID: 37422193 PMCID: PMC10403730 DOI: 10.1016/j.jbc.2023.105019] [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: 03/08/2023] [Revised: 06/24/2023] [Accepted: 06/26/2023] [Indexed: 07/10/2023] Open
Abstract
Poly(A)-binding protein nuclear 1 (PABPN1) is an RNA-binding protein localized in nuclear speckles, while its alanine (Ala)-expanded variants accumulate as intranuclear aggregates in oculopharyngeal muscular dystrophy. The factors that drive PABPN1 aggregation and its cellular consequences remain largely unknown. Here, we investigated the roles of Ala stretch and poly(A) RNA in the phase transition of PABPN1 using biochemical and molecular cell biology methods. We have revealed that the Ala stretch controls its mobility in nuclear speckles, and Ala expansion leads to aggregation from the dynamic speckles. Poly(A) nucleotide is essential to the early-stage condensation that thereby facilitates speckle formation and transition to solid-like aggregates. Moreover, the PABPN1 aggregates can sequester CFIm25, a component of the pre-mRNA 3'-UTR processing complex, in an mRNA-dependent manner and consequently impair the function of CFIm25 in alternative polyadenylation. In conclusion, our study elucidates a molecular mechanism underlying PABPN1 aggregation and sequestration, which will be beneficial for understanding PABPN1 proteinopathy.
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Affiliation(s)
- Wen-Liang Guan
- State Key Laboratory of Molecular Biology, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, Shanghai, China; University of Chinese Academy of Sciences, Beijing, China
| | - Lei-Lei Jiang
- State Key Laboratory of Molecular Biology, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, Shanghai, China
| | - Xiao-Fang Yin
- State Key Laboratory of Molecular Biology, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, Shanghai, China; University of Chinese Academy of Sciences, Beijing, China
| | - Hong-Yu Hu
- State Key Laboratory of Molecular Biology, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, Shanghai, China.
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3
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Assessment of PABPN1 nuclear inclusions on a large cohort of patients and in a human xenograft model of oculopharyngeal muscular dystrophy. Acta Neuropathol 2022; 144:1157-1170. [PMID: 36197469 PMCID: PMC9637588 DOI: 10.1007/s00401-022-02503-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Revised: 08/26/2022] [Accepted: 09/17/2022] [Indexed: 01/26/2023]
Abstract
Oculopharyngeal muscular dystrophy (OPMD) is a rare muscle disease characterized by an onset of weakness in the pharyngeal and eyelid muscles. The disease is caused by the extension of a polyalanine tract in the Poly(A) Binding Protein Nuclear 1 (PABPN1) protein leading to the formation of intranuclear inclusions or aggregates in the muscle of OPMD patients. Despite numerous studies stressing the deleterious role of nuclear inclusions in cellular and animal OPMD models, their exact contribution to human disease is still unclear. In this study, we used a large and unique collection of human muscle biopsy samples to perform an in-depth analysis of PABPN1 aggregates in relation to age, genotype and muscle status with the final aim to improve our understanding of OPMD physiopathology. Here we demonstrate that age and genotype influence PABPN1 aggregates: the percentage of myonuclei containing PABPN1 aggregates increases with age and the chaperone HSP70 co-localize more frequently with PABPN1 aggregates with a larger polyalanine tract. In addition to the previously described PRMT1 and HSP70 co-factors, we identified new components of PABPN1 aggregates including GRP78/BiP, RPL24 and p62. We also observed that myonuclei containing aggregates are larger than myonuclei without. When comparing two muscles from the same patient, a similar amount of aggregates is observed in different muscles, except for the pharyngeal muscle where fewer aggregates are observed. This could be due to the peculiar nature of this muscle which has a low level of PAPBN1 and contains regenerating fibers. To confirm the fate of PABPN1 aggregates in a regenerating muscle, we generated a xenograft model by transplanting human OPMD muscle biopsy samples into the hindlimb of an immunodeficient mouse. Xenografts from subjects with OPMD displayed regeneration of human myofibers and PABPN1 aggregates were rapidly present-although to a lower extent-after muscle fiber regeneration. Our data obtained on human OPMD samples add support to the dual non-exclusive models in OPMD combining toxic PABPN1 intranuclear inclusions together with PABPN1 loss of function which altogether result in this late-onset and muscle selective disease.
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4
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Qin J, Autexier C. Regulation of human telomerase RNA biogenesis and localization. RNA Biol 2021; 18:305-315. [PMID: 32813614 PMCID: PMC7954027 DOI: 10.1080/15476286.2020.1809196] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 08/03/2020] [Accepted: 08/08/2020] [Indexed: 12/16/2022] Open
Abstract
Maintenance of telomeres is essential for genome integrity and replicative capacity in eukaryotic cells. Telomerase, the ribonucleoprotein complex that catalyses telomere synthesis is minimally composed of a reverse transcriptase and an RNA component. The sequence and structural domains of human telomerase RNA (hTR) have been extensively characterized, while the regulation of hTR transcription, maturation, and localization, is not fully understood. Here, we provide an up-to-date review of hTR, with an emphasis on current breakthroughs uncovering the mechanisms of hTR maturation and localization.
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Affiliation(s)
- Jian Qin
- Department of Anatomy and Cell Biology, McGill University, Montreal, Quebec, Canada
- Jewish General Hospital, Lady Davis Institute, Montreal, Quebec, Canada
| | - Chantal Autexier
- Department of Anatomy and Cell Biology, McGill University, Montreal, Quebec, Canada
- Jewish General Hospital, Lady Davis Institute, Montreal, Quebec, Canada
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5
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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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6
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Galimberti V, Tironi R, Lerario A, Scali M, Del Bo R, Rodolico C, Brizzi T, Gibertini S, Maggi L, Mora M, Toscano A, Comi GP, Sciacco M, Moggio M, Peverelli L. Value of insoluble PABPN1 accumulation in the diagnosis of oculopharyngeal muscular dystrophy. Eur J Neurol 2019; 27:709-715. [DOI: 10.1111/ene.14131] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2019] [Accepted: 11/18/2019] [Indexed: 12/13/2022]
Affiliation(s)
- V. Galimberti
- Neuromuscular and Rare Disease Unit Department of Neuroscience Foundation IRCCS Ca’ Granda Ospedale Maggiore Policlinico Milano Italy
| | - R. Tironi
- Neuromuscular and Rare Disease Unit Department of Neuroscience Foundation IRCCS Ca’ Granda Ospedale Maggiore Policlinico Milano Italy
| | - A. Lerario
- Neuromuscular and Rare Disease Unit Department of Neuroscience Foundation IRCCS Ca’ Granda Ospedale Maggiore Policlinico Milano Italy
| | - M. Scali
- Neuromuscular and Rare Disease Unit Department of Neuroscience Foundation IRCCS Ca’ Granda Ospedale Maggiore Policlinico Milano Italy
| | - R. Del Bo
- Dino Ferrari Centre Neuroscience Section Department of Pathophysiology and Transplantation (DEPT) University of Milan MilanoItaly
- Neurology Unit IRCCS Foundation Ca’ Granda Ospedale Maggiore Policlinico Milano Italy
| | - C. Rodolico
- Neurology and Neuromuscular Diseases Unit Department of Clinical and Experimental Medicine University of Messina Messina Italy
| | - T. Brizzi
- Neurology and Neuromuscular Diseases Unit Department of Clinical and Experimental Medicine University of Messina Messina Italy
- DIBIMIS University of Palermo Palermo Italy
| | - S. Gibertini
- Neuromuscular Diseases and Neuroimmunology Unit Fondazione IRCCS Istituto Neurologico Carlo Besta Milano Italy
| | - L. Maggi
- Neuromuscular Diseases and Neuroimmunology Unit Fondazione IRCCS Istituto Neurologico Carlo Besta Milano Italy
| | - M. Mora
- Neuromuscular Diseases and Neuroimmunology Unit Fondazione IRCCS Istituto Neurologico Carlo Besta Milano Italy
| | - A. Toscano
- Neurology and Neuromuscular Diseases Unit Department of Clinical and Experimental Medicine University of Messina Messina Italy
| | - G. P. Comi
- Dino Ferrari Centre Neuroscience Section Department of Pathophysiology and Transplantation (DEPT) University of Milan MilanoItaly
- Neurology Unit IRCCS Foundation Ca’ Granda Ospedale Maggiore Policlinico Milano Italy
| | - M. Sciacco
- Neuromuscular and Rare Disease Unit Department of Neuroscience Foundation IRCCS Ca’ Granda Ospedale Maggiore Policlinico Milano Italy
| | - M. Moggio
- Neuromuscular and Rare Disease Unit Department of Neuroscience Foundation IRCCS Ca’ Granda Ospedale Maggiore Policlinico Milano Italy
| | - L. Peverelli
- Neuromuscular and Rare Disease Unit Department of Neuroscience Foundation IRCCS Ca’ Granda Ospedale Maggiore Policlinico Milano Italy
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7
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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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8
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Narcís JO, Tapia O, Tarabal O, Piedrafita L, Calderó J, Berciano MT, Lafarga M. Accumulation of poly(A) RNA in nuclear granules enriched in Sam68 in motor neurons from the SMNΔ7 mouse model of SMA. Sci Rep 2018; 8:9646. [PMID: 29941967 PMCID: PMC6018117 DOI: 10.1038/s41598-018-27821-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Accepted: 06/11/2018] [Indexed: 01/07/2023] Open
Abstract
Spinal muscular atrophy (SMA) is a severe motor neuron (MN) disease caused by the deletion or mutation of the survival motor neuron 1 (SMN1) gene, which results in reduced levels of the SMN protein and the selective degeneration of lower MNs. The best-known function of SMN is the biogenesis of spliceosomal snRNPs, the major components of the pre-mRNA splicing machinery. Therefore, SMN deficiency in SMA leads to widespread splicing abnormalities. We used the SMN∆7 mouse model of SMA to investigate the cellular reorganization of polyadenylated mRNAs associated with the splicing dysfunction in MNs. We demonstrate that SMN deficiency induced the abnormal nuclear accumulation in euchromatin domains of poly(A) RNA granules (PARGs) enriched in the splicing regulator Sam68. However, these granules lacked other RNA-binding proteins, such as TDP43, PABPN1, hnRNPA12B, REF and Y14, which are essential for mRNA processing and nuclear export. These effects were accompanied by changes in the alternative splicing of the Sam68-dependent Bcl-x and Nrnx1 genes, as well as changes in the relative accumulation of the intron-containing Chat, Chodl, Myh9 and Myh14 mRNAs, which are all important for MN functions. PARG-containing MNs were observed at presymptomatic SMA stage, increasing their number during the symptomatic stage. Moreover, the massive accumulations of poly(A) RNA granules in MNs was accompanied by the cytoplasmic depletion of polyadenylated mRNAs for their translation. We suggest that the SMN-dependent abnormal accumulation of polyadenylated mRNAs and Sam68 in PARGs reflects a severe dysfunction of both mRNA processing and translation, which could contribute to SMA pathogenesis.
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Affiliation(s)
- J Oriol Narcís
- Department of Anatomy and Cell Biology and "Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED)", University of Cantabria-IDIVAL, Santander, Spain
| | - Olga Tapia
- Department of Anatomy and Cell Biology and "Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED)", University of Cantabria-IDIVAL, Santander, Spain
| | - Olga Tarabal
- Department of Experimental Medicine, School of Medicine, University of Lleida and "Institut de Recerca Biomèdica de Lleida" (IRBLLEIDA), Lleida, Spain
| | - Lídia Piedrafita
- Department of Experimental Medicine, School of Medicine, University of Lleida and "Institut de Recerca Biomèdica de Lleida" (IRBLLEIDA), Lleida, Spain
| | - Jordi Calderó
- Department of Experimental Medicine, School of Medicine, University of Lleida and "Institut de Recerca Biomèdica de Lleida" (IRBLLEIDA), Lleida, Spain
| | - Maria T Berciano
- Department of Anatomy and Cell Biology and "Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED)", University of Cantabria-IDIVAL, Santander, Spain.,Department of Molecular Biology and CIBERNED, University of Cantabria-IDIVAL, Santander, Spain
| | - Miguel Lafarga
- Department of Anatomy and Cell Biology and "Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED)", University of Cantabria-IDIVAL, Santander, Spain.
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9
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Wegener M, Müller-McNicoll M. Nuclear retention of mRNAs - quality control, gene regulation and human disease. Semin Cell Dev Biol 2017; 79:131-142. [PMID: 29102717 DOI: 10.1016/j.semcdb.2017.11.001] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Revised: 10/30/2017] [Accepted: 11/01/2017] [Indexed: 12/21/2022]
Abstract
Nuclear retention of incompletely spliced or mature mRNAs emerges as a novel, previously underappreciated layer of gene regulation, which enables the cell to rapidly respond to stress, viral infection, differentiation cues or changing environmental conditions. Focusing on mammalian cells, we discuss recent insights into the mechanisms and functions of nuclear retention, describe retention-promoting features in protein-coding transcripts and propose mechanisms for their regulated release into the cytoplasm. Moreover, we discuss examples of how aberrant nuclear retention of mRNAs may lead to human diseases.
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Affiliation(s)
- Marius Wegener
- RNA Regulation Group, Cluster of Excellence 'Macromolecular Complexes', Goethe University Frankfurt, Institute of Cell Biology and Neuroscience, Max-von-Laue-Str. 13, 60438 Frankfurt/Main, Germany
| | - Michaela Müller-McNicoll
- RNA Regulation Group, Cluster of Excellence 'Macromolecular Complexes', Goethe University Frankfurt, Institute of Cell Biology and Neuroscience, Max-von-Laue-Str. 13, 60438 Frankfurt/Main, Germany.
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10
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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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11
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Richard P, Roth F, Stojkovic T, Trollet C. Distrofia muscolare oculofaringea. Neurologia 2017. [DOI: 10.1016/s1634-7072(16)81777-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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12
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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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13
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Vest KE, Apponi LH, Banerjee A, Pavlath GK, Corbett AH. An Antibody to Detect Alanine-Expanded PABPN1: A New Tool to Study Oculopharyngeal Muscular Dystrophy. J Neuromuscul Dis 2015; 2:439-446. [PMID: 27858752 PMCID: PMC5207656 DOI: 10.3233/jnd-150111] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND Oculopharyngeal muscular dystrophy (OPMD), a late onset disorder affecting specific skeletal muscles, is caused by a (GCG)n expansion mutation in the gene encoding the mRNA processing protein, polyadenylate binding protein nuclear 1 (PABPN1). The expansion in PABPN1 leads to an increase in a stretch of N-terminal alanine residues in the PABPN1 protein from the normal 10 to 12-18. Given this modest change, detection of mutant protein has not been possible without the use of tagged constructs. OBJECTIVE We sought to generate a polyclonal antibody that recognizes alanine-expanded but not wild type PABPN1 with the goal of making possible analysis of expression and localization of alanine-expanded PABPN1. METHODS We immunized rabbits with a GST-tagged alanine peptide and tested the resulting serum against alanine-expanded PABPN1 expressed in cell culture as well as in animal models of OPMD. RESULTS The resulting α-alanine antibody detected PABPN1 proteins that contained 14 or more alanine residues. Importantly, the α-alanine antibody could be used to detect alanine-expanded PABPN1 in muscles from either a mouse or Drosophila model of OPMD. CONCLUSIONS This α-alanine antibody provides a new tool that will allow for more in-depth study of how alanine expansion affects aggregation, localization, and steady-state levels of alanine-expanded PABPN1 levels in vivo, providing new insight into the molecular mechanisms underlying OPMD.
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Affiliation(s)
- Katherine E Vest
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA, USA.,Department of Pharmacology, Emory University School of Medicine, Atlanta, GA, USA
| | - Luciano H Apponi
- Department of Pharmacology, Emory University School of Medicine, Atlanta, GA, USA.,Dicerna Pharmaceuticals, Inc., Cambridge, MA, USA
| | - Ayan Banerjee
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA, USA
| | - Grace K Pavlath
- Department of Pharmacology, Emory University School of Medicine, Atlanta, GA, USA
| | - Anita H Corbett
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA, USA
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14
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The Inhibition of Heat Shock Protein 90 Facilitates the Degradation of Poly-Alanine Expanded Poly (A) Binding Protein Nuclear 1 via the Carboxyl Terminus of Heat Shock Protein 70-Interacting Protein. PLoS One 2015; 10:e0138936. [PMID: 26414348 PMCID: PMC4587574 DOI: 10.1371/journal.pone.0138936] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Accepted: 09/06/2015] [Indexed: 01/24/2023] Open
Abstract
Background Since the identification of poly-alanine expanded poly(A) binding protein nuclear 1 (PABPN1) as the genetic cause of oculopharyngeal muscular dystrophy (OPMD), considerable progress has been made in our understanding of the pathogenesis of the disease. However, the molecular mechanisms that regulate the onset and progression of the disease remain unclear. Results In this study, we show that PABPN1 interacts with and is stabilized by heat shock protein 90 (HSP90). Treatment with the HSP90 inhibitor 17-AAG disrupted the interaction of mutant PABPN1 with HSP90 and reduced the formation of intranuclear inclusions (INIs). Furthermore, mutant PABPN1 was preferentially degraded in the presence of 17-AAG compared with wild-type PABPN1 in vitro and in vivo. The effect of 17-AAG was mediated through an increase in the interaction of PABPN1 with the carboxyl terminus of heat shock protein 70-interacting protein (CHIP). The overexpression of CHIP suppressed the aggregation of mutant PABPN1 in transfected cells. Conclusions Our results demonstrate that the HSP90 molecular chaperone system plays a crucial role in the selective elimination of abnormal PABPN1 proteins and also suggest a potential therapeutic application of the HSP90 inhibitor 17-AAG for the treatment of OPMD.
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15
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Cooper-Knock J, Higginbottom A, Stopford MJ, Highley JR, Ince PG, Wharton SB, Pickering-Brown S, Kirby J, Hautbergue GM, Shaw PJ. Antisense RNA foci in the motor neurons of C9ORF72-ALS patients are associated with TDP-43 proteinopathy. Acta Neuropathol 2015; 130:63-75. [PMID: 25943887 PMCID: PMC4468790 DOI: 10.1007/s00401-015-1429-9] [Citation(s) in RCA: 128] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2015] [Revised: 04/08/2015] [Accepted: 04/20/2015] [Indexed: 12/14/2022]
Abstract
GGGGCC repeat expansions of C9ORF72 represent the most common genetic variant of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia. We and others have proposed that RNA transcribed from the repeat sequence is toxic via sequestration of RNA-binding factors. Both GGGGCC-repeat (sense) and CCCCGG-repeat (antisense) molecules are detectable by fluorescence in situ hybridisation as RNA foci, but their relative expression pattern within the CNS and contribution to disease has not been determined. Blinded examination of CNS biosamples from ALS patients with a repeat expansion of C9ORF72 showed that antisense foci are present at a significantly higher frequency in cerebellar Purkinje neurons and motor neurons, whereas sense foci are present at a significantly higher frequency in cerebellar granule neurons. Consistent with this, inclusions containing sense or antisense derived dipeptide repeat proteins were present at significantly higher frequency in cerebellar granule neurons or motor neurons, respectively. Immunohistochemistry and UV-crosslinking studies showed that sense and antisense RNA molecules share similar interactions with SRSF2, hnRNP K, hnRNP A1, ALYREF, and hnRNP H/F. Together these data suggest that, although sense and antisense RNA molecules might be expected to be equally toxic via their shared protein binding partners, distinct patterns of expression in various CNS neuronal populations could lead to relative differences in their contribution to the pathogenesis of neuronal injury. Moreover in motor neurons, which are the primary target of pathology in ALS, the presence of antisense foci (χ (2), p < 0.00001) but not sense foci (χ (2), p = 0.75) correlated with mislocalisation of TDP-43, which is the hallmark of ALS neurodegeneration. This has implications for translational approaches to C9ORF72 disease, and furthermore interacting RNA-processing factors and transcriptional activators responsible for antisense versus sense transcription might represent novel therapeutic targets.
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Affiliation(s)
- Johnathan Cooper-Knock
- />Sheffield Institute for Translational Neuroscience (SITraN), University of Sheffield, 385A Glossop Road, Sheffield, S10 2HQ UK
| | - Adrian Higginbottom
- />Sheffield Institute for Translational Neuroscience (SITraN), University of Sheffield, 385A Glossop Road, Sheffield, S10 2HQ UK
| | - Matthew J. Stopford
- />Sheffield Institute for Translational Neuroscience (SITraN), University of Sheffield, 385A Glossop Road, Sheffield, S10 2HQ UK
| | - J. Robin Highley
- />Sheffield Institute for Translational Neuroscience (SITraN), University of Sheffield, 385A Glossop Road, Sheffield, S10 2HQ UK
| | - Paul G. Ince
- />Sheffield Institute for Translational Neuroscience (SITraN), University of Sheffield, 385A Glossop Road, Sheffield, S10 2HQ UK
| | - Stephen B. Wharton
- />Sheffield Institute for Translational Neuroscience (SITraN), University of Sheffield, 385A Glossop Road, Sheffield, S10 2HQ UK
| | - Stuart Pickering-Brown
- />Institute of Brain, Behaviour and Mental Health, 2.014 AV Hill Building, University of Manchester, Manchester, M13 9PT UK
| | - Janine Kirby
- />Sheffield Institute for Translational Neuroscience (SITraN), University of Sheffield, 385A Glossop Road, Sheffield, S10 2HQ UK
| | - Guillaume M. Hautbergue
- />Sheffield Institute for Translational Neuroscience (SITraN), University of Sheffield, 385A Glossop Road, Sheffield, S10 2HQ UK
| | - Pamela J. Shaw
- />Sheffield Institute for Translational Neuroscience (SITraN), University of Sheffield, 385A Glossop Road, Sheffield, S10 2HQ UK
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16
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Cooper-Knock J, Walsh MJ, Higginbottom A, Robin Highley J, Dickman MJ, Edbauer D, Ince PG, Wharton SB, Wilson SA, Kirby J, Hautbergue GM, Shaw PJ. Sequestration of multiple RNA recognition motif-containing proteins by C9orf72 repeat expansions. ACTA ACUST UNITED AC 2014; 137:2040-51. [PMID: 24866055 PMCID: PMC4065024 DOI: 10.1093/brain/awu120] [Citation(s) in RCA: 229] [Impact Index Per Article: 22.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Expansion of GGGGCC repeats in C9orf72 causes familial amyotrophic lateral sclerosis (ALS) and frontotemporal dementia, but the underlying mechanism is unclear. Using RNA pulldown and immunohistochemistry in ALS biosamples, Cooper-Knock et al. identify proteins that bind to the repeat expansions. Disrupted RNA splicing and/or nuclear export may underlie C9orf72-ALS pathogenesis. GGGGCC repeat expansions of C9orf72 represent the most common genetic variant of amyotrophic lateral sclerosis and frontotemporal degeneration, but the mechanism of pathogenesis is unclear. Recent reports have suggested that the transcribed repeat might form toxic RNA foci that sequester various RNA processing proteins. Consensus as to the identity of the binding partners is missing and whole neuronal proteome investigation is needed. Using RNA fluorescence in situ hybridization we first identified nuclear and cytoplasmic RNA foci in peripheral and central nervous system biosamples from patients with amyotrophic lateral sclerosis with a repeat expansion of C9orf72 (C9orf72+), but not from those patients without a repeat expansion of C9orf72 (C9orf72−) or control subjects. Moreover, in the cases examined, the distribution of foci-positive neurons correlated with the clinical phenotype (t-test P < 0.05). As expected, RNA foci are ablated by RNase treatment. Interestingly, we identified foci in fibroblasts from an asymptomatic C9orf72+ carrier. We next performed pulldown assays, with GGGGCC5, in conjunction with mass spectrometry analysis, to identify candidate binding partners of the GGGGCC repeat expansion. Proteins containing RNA recognition motifs and involved in splicing, messenger RNA nuclear export and/or translation were significantly enriched. Immunohistochemistry in central nervous system tissue from C9orf72+ patients with amyotrophic lateral sclerosis demonstrated co-localization of RNA foci with SRSF2, hnRNP H1/F, ALYREF and hnRNP A1 in cerebellar granule cells and with SRSF2, hnRNP H1/F and ALYREF in motor neurons, the primary target of pathology in amyotrophic lateral sclerosis. Direct binding of proteins to GGGGCC repeat RNA was confirmed in vitro by ultraviolet-crosslinking assays. Co-localization was only detected in a small proportion of RNA foci, suggesting dynamic sequestration rather than irreversible binding. Additional immunohistochemistry demonstrated that neurons with and without RNA foci were equally likely to show nuclear depletion of TDP-43 (χ2P = 0.75) or poly-GA dipeptide repeat protein inclusions (χ2P = 0.46). Our findings suggest two non-exclusive pathogenic mechanisms: (i) functional depletion of RNA-processing proteins resulting in disruption of messenger RNA splicing; and (ii) licensing of expanded C9orf72 pre-messenger RNA for nuclear export by inappropriate association with messenger RNA export adaptor protein(s) leading to cytoplasmic repeat associated non-ATG translation and formation of potentially toxic dipeptide repeat protein.
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Affiliation(s)
- Johnathan Cooper-Knock
- 1 Sheffield Institute for Translational Neuroscience (SITraN), University of Sheffield, 385A Glossop Road, Sheffield S10 2HQ, UK
| | - Matthew J Walsh
- 1 Sheffield Institute for Translational Neuroscience (SITraN), University of Sheffield, 385A Glossop Road, Sheffield S10 2HQ, UK
| | - Adrian Higginbottom
- 1 Sheffield Institute for Translational Neuroscience (SITraN), University of Sheffield, 385A Glossop Road, Sheffield S10 2HQ, UK
| | - J Robin Highley
- 1 Sheffield Institute for Translational Neuroscience (SITraN), University of Sheffield, 385A Glossop Road, Sheffield S10 2HQ, UK
| | - Mark J Dickman
- 2 Chemical and Biological Engineering, ChELSI Institute, University of Sheffield, Mappin Street, Sheffield, S1 3JD, UK
| | - Dieter Edbauer
- 3 DZNE-German Centre for Neurodegenerative Diseases and Munich Cluster of Systems Neurology (SyNergy), Munich, Germany
| | - Paul G Ince
- 1 Sheffield Institute for Translational Neuroscience (SITraN), University of Sheffield, 385A Glossop Road, Sheffield S10 2HQ, UK
| | - Stephen B Wharton
- 1 Sheffield Institute for Translational Neuroscience (SITraN), University of Sheffield, 385A Glossop Road, Sheffield S10 2HQ, UK
| | - Stuart A Wilson
- 4 Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Sheffield, S10 2TN, UK
| | - Janine Kirby
- 1 Sheffield Institute for Translational Neuroscience (SITraN), University of Sheffield, 385A Glossop Road, Sheffield S10 2HQ, UK
| | - Guillaume M Hautbergue
- 1 Sheffield Institute for Translational Neuroscience (SITraN), University of Sheffield, 385A Glossop Road, Sheffield S10 2HQ, UK
| | - Pamela J Shaw
- 1 Sheffield Institute for Translational Neuroscience (SITraN), University of Sheffield, 385A Glossop Road, Sheffield S10 2HQ, UK
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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: 84] [Impact Index Per Article: 7.6] [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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