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Tilliole P, Fix S, Godin JD. hnRNPs: roles in neurodevelopment and implication for brain disorders. Front Mol Neurosci 2024; 17:1411639. [PMID: 39086926 PMCID: PMC11288931 DOI: 10.3389/fnmol.2024.1411639] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2024] [Accepted: 06/17/2024] [Indexed: 08/02/2024] Open
Abstract
Heterogeneous nuclear ribonucleoproteins (hnRNPs) constitute a family of multifunctional RNA-binding proteins able to process nuclear pre-mRNAs into mature mRNAs and regulate gene expression in multiple ways. They comprise at least 20 different members in mammals, named from A (HNRNP A1) to U (HNRNP U). Many of these proteins are components of the spliceosome complex and can modulate alternative splicing in a tissue-specific manner. Notably, while genes encoding hnRNPs exhibit ubiquitous expression, increasing evidence associate these proteins to various neurodevelopmental and neurodegenerative disorders, such as intellectual disability, epilepsy, microcephaly, amyotrophic lateral sclerosis, or dementias, highlighting their crucial role in the central nervous system. This review explores the evolution of the hnRNPs family, highlighting the emergence of numerous new members within this family, and sheds light on their implications for brain development.
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Affiliation(s)
- Pierre Tilliole
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, IGBMC, Illkirch, France
- Centre National de la Recherche Scientifique, CNRS, UMR7104, Illkirch, France
- Institut National de la Santé et de la Recherche Médicale, INSERM, U1258, Illkirch, France
- Université de Strasbourg, Strasbourg, France
| | - Simon Fix
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, IGBMC, Illkirch, France
- Centre National de la Recherche Scientifique, CNRS, UMR7104, Illkirch, France
- Institut National de la Santé et de la Recherche Médicale, INSERM, U1258, Illkirch, France
- Université de Strasbourg, Strasbourg, France
| | - Juliette D. Godin
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, IGBMC, Illkirch, France
- Centre National de la Recherche Scientifique, CNRS, UMR7104, Illkirch, France
- Institut National de la Santé et de la Recherche Médicale, INSERM, U1258, Illkirch, France
- Université de Strasbourg, Strasbourg, France
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2
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Fischer S, Lichtenthaeler C, Stepanenko A, Heyl F, Maticzka D, Kemmerer K, Klostermann M, Backofen R, Zarnack K, Weigand JE. Heterogenous nuclear ribonucleoprotein D-like controls endothelial cell functions. Biol Chem 2024; 405:229-239. [PMID: 37942876 DOI: 10.1515/hsz-2023-0254] [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: 07/05/2023] [Accepted: 10/19/2023] [Indexed: 11/10/2023]
Abstract
HnRNPs are ubiquitously expressed RNA-binding proteins, tightly controlling posttranscriptional gene regulation. Consequently, hnRNP networks are essential for cellular homeostasis and their dysregulation is associated with cancer and other diseases. However, the physiological function of hnRNPs in non-cancerous cell systems are poorly understood. We analyzed the importance of HNRNPDL in endothelial cell functions. Knockdown of HNRNPDL led to impaired proliferation, migration and sprouting of spheroids. Transcriptome analysis identified cyclin D1 (CCND1) and tropomyosin 4 (TPM4) as targets of HNRNPDL, reflecting the phenotypic changes after knockdown. Our findings underline the importance of HNRNPDL for the homeostasis of physiological processes in endothelial cells.
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Affiliation(s)
- Sandra Fischer
- Department of Pharmacy, Institute of Pharmaceutical Chemistry, University of Marburg, Marbacher Weg 6, D-35037 Marburg, Germany
| | - Chiara Lichtenthaeler
- Department of Pharmacy, Institute of Pharmaceutical Chemistry, University of Marburg, Marbacher Weg 6, D-35037 Marburg, Germany
| | - Anastasiya Stepanenko
- Buchmann Institute for Molecular Life Sciences and Institute of Molecular Biosciences, Goethe University Frankfurt, Max-von-Laue-Str. 15, D-60438 Frankfurt am Main, Germany
| | - Florian Heyl
- Department of Bioinformatics, University of Freiburg, Georges-Köhler-Allee 106, D-79110 Freiburg, Germany
| | - Daniel Maticzka
- Department of Bioinformatics, University of Freiburg, Georges-Köhler-Allee 106, D-79110 Freiburg, Germany
| | - Katrin Kemmerer
- Department of Pharmacy, Institute of Pharmaceutical Chemistry, University of Marburg, Marbacher Weg 6, D-35037 Marburg, Germany
| | - Melina Klostermann
- Buchmann Institute for Molecular Life Sciences and Institute of Molecular Biosciences, Goethe University Frankfurt, Max-von-Laue-Str. 15, D-60438 Frankfurt am Main, Germany
| | - Rolf Backofen
- Department of Bioinformatics, University of Freiburg, Georges-Köhler-Allee 106, D-79110 Freiburg, Germany
| | - Kathi Zarnack
- Buchmann Institute for Molecular Life Sciences and Institute of Molecular Biosciences, Goethe University Frankfurt, Max-von-Laue-Str. 15, D-60438 Frankfurt am Main, Germany
| | - Julia E Weigand
- Department of Pharmacy, Institute of Pharmaceutical Chemistry, University of Marburg, Marbacher Weg 6, D-35037 Marburg, Germany
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3
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Wu J, Niu L, Yang K, Xu J, Zhang D, Ling J, Xia P, Wu Y, Liu X, Liu J, Zhang J, Yu P. The role and mechanism of RNA-binding proteins in bone metabolism and osteoporosis. Ageing Res Rev 2024; 96:102234. [PMID: 38367813 DOI: 10.1016/j.arr.2024.102234] [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: 10/11/2023] [Revised: 02/06/2024] [Accepted: 02/13/2024] [Indexed: 02/19/2024]
Abstract
Osteoporosis is a prevalent chronic metabolic bone disease that poses a significant risk of fractures or mortality in elderly individuals. Its pathophysiological basis is often attributed to postmenopausal estrogen deficiency and natural aging, making the progression of primary osteoporosis among elderly people, especially older women, seemingly inevitable. The treatment and prevention of osteoporosis progression have been extensively discussed. Recently, as researchers delve deeper into the molecular biological mechanisms of bone remodeling, they have come to realize the crucial role of posttranscriptional gene control in bone metabolism homeostasis. RNA-binding proteins, as essential actors in posttranscriptional activities, may exert influence on osteoporosis progression by regulating the RNA life cycle. This review compiles recent findings on the involvement of RNA-binding proteins in abnormal bone metabolism in osteoporosis and describes the impact of some key RNA-binding proteins on bone metabolism regulation. Additionally, we explore the potential and rationale for modulating RNA-binding proteins as a means of treating osteoporosis, with an overview of drugs that target these proteins.
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Affiliation(s)
- Jiaqiang Wu
- Jiujiang Clinical Precision Medicine Research Center, Jiujiang, Jiangxi, 332000, China; The Second Affiliated Hospital, Jiangxi Medical College, Nanchang University, Nanchang 330006, China; Department of General Surgery, First Medical Center of the Chinese PLA General Hospital, Beijing, China
| | - Liyan Niu
- HuanKui College of Nanchang University, Nanchang 330006, China
| | - Kangping Yang
- The Second Affiliated Hospital, Jiangxi Medical College, Nanchang University, Nanchang 330006, China
| | - Jingdong Xu
- Queen Mary College of Nanchang University, Nanchang 330006, China
| | - Deju Zhang
- Food and Nutritional Sciences, School of Biological Sciences, The University of Hong Kong, Pokfulam Road, 999077, Hong Kong, China
| | - Jitao Ling
- Department of Endocrinology and Metabolism, The Second Affiliated Hospital, Jiangxi Medical College, Nanchang University, No. 1, Minde Road, Donghu District, Nanchang 330006, China; Institute for the Study of Endocrinology and Metabolism in Jiangxi Province, Nanchang 330006, China
| | - Panpan Xia
- Department of Endocrinology and Metabolism, The Second Affiliated Hospital, Jiangxi Medical College, Nanchang University, No. 1, Minde Road, Donghu District, Nanchang 330006, China; Institute for the Study of Endocrinology and Metabolism in Jiangxi Province, Nanchang 330006, China
| | - Yuting Wu
- Department of Endocrinology and Metabolism, The Second Affiliated Hospital, Jiangxi Medical College, Nanchang University, No. 1, Minde Road, Donghu District, Nanchang 330006, China; Institute for the Study of Endocrinology and Metabolism in Jiangxi Province, Nanchang 330006, China
| | - Xiao Liu
- Department of Cardiology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou 510275, China
| | - Jianping Liu
- Department of Endocrinology and Metabolism, The Second Affiliated Hospital, Jiangxi Medical College, Nanchang University, No. 1, Minde Road, Donghu District, Nanchang 330006, China; Institute for the Study of Endocrinology and Metabolism in Jiangxi Province, Nanchang 330006, China
| | - Jing Zhang
- Jiujiang Clinical Precision Medicine Research Center, Jiujiang, Jiangxi, 332000, China; Department of Anesthesiology, The Second Affiliated Hospital, Jiangxi Medical College, Nanchang University, Nanchang, Jiangxi, 330006, China.
| | - Peng Yu
- Jiujiang Clinical Precision Medicine Research Center, Jiujiang, Jiangxi, 332000, China; Department of Endocrinology and Metabolism, The Second Affiliated Hospital, Jiangxi Medical College, Nanchang University, No. 1, Minde Road, Donghu District, Nanchang 330006, China; Institute for the Study of Endocrinology and Metabolism in Jiangxi Province, Nanchang 330006, China.
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Abedeera SM, Davila-Calderon J, Haddad C, Henry B, King J, Penumutchu S, Tolbert BS. The Repurposing of Cellular Proteins during Enterovirus A71 Infection. Viruses 2023; 16:75. [PMID: 38257775 PMCID: PMC10821071 DOI: 10.3390/v16010075] [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: 12/09/2023] [Revised: 12/27/2023] [Accepted: 12/29/2023] [Indexed: 01/24/2024] Open
Abstract
Viruses pose a great threat to people's lives. Enterovirus A71 (EV-A71) infects children and infants all over the world with no FDA-approved treatment to date. Understanding the basic mechanisms of viral processes aids in selecting more efficient drug targets and designing more effective antivirals to thwart this virus. The 5'-untranslated region (5'-UTR) of the viral RNA genome is composed of a cloverleaf structure and an internal ribosome entry site (IRES). Cellular proteins that bind to the cloverleaf structure regulate viral RNA synthesis, while those that bind to the IRES also known as IRES trans-acting factors (ITAFs) regulate viral translation. In this review, we survey the cellular proteins currently known to bind the 5'-UTR and influence viral gene expression with emphasis on comparing proteins' functions and localizations pre- and post-(EV-A71) infection. A comprehensive understanding of how the host cell's machinery is hijacked and reprogrammed by the virus to facilitate its replication is crucial for developing effective antivirals.
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Affiliation(s)
- Sudeshi M. Abedeera
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; (S.M.A.); (B.H.); (S.P.)
| | - Jesse Davila-Calderon
- Department of Chemistry, Case Western Reserve University, Cleveland, OH 44106, USA; (J.D.-C.); (C.H.); (J.K.)
| | - Christina Haddad
- Department of Chemistry, Case Western Reserve University, Cleveland, OH 44106, USA; (J.D.-C.); (C.H.); (J.K.)
| | - Barrington Henry
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; (S.M.A.); (B.H.); (S.P.)
| | - Josephine King
- Department of Chemistry, Case Western Reserve University, Cleveland, OH 44106, USA; (J.D.-C.); (C.H.); (J.K.)
| | - Srinivasa Penumutchu
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; (S.M.A.); (B.H.); (S.P.)
| | - Blanton S. Tolbert
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; (S.M.A.); (B.H.); (S.P.)
- Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA
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Farshadyeganeh P, Nazim M, Zhang R, Ohkawara B, Nakajima K, Rahman MA, Nasrin F, Ito M, Takeda JI, Ohe K, Miyasaka Y, Ohno T, Masuda A, Ohno K. Splicing regulation of GFPT1 muscle-specific isoform and its roles in glucose metabolisms and neuromuscular junction. iScience 2023; 26:107746. [PMID: 37744035 PMCID: PMC10514471 DOI: 10.1016/j.isci.2023.107746] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Revised: 07/29/2023] [Accepted: 08/24/2023] [Indexed: 09/26/2023] Open
Abstract
Glutamine:fructose-6-phosphate transaminase 1 (GFPT1) is the rate-limiting enzyme of the hexosamine biosynthetic pathway (HBP). A 54-bp exon 9 of GFPT1 is specifically included in skeletal and cardiac muscles to generate a long isoform of GFPT1 (GFPT1-L). We showed that SRSF1 and Rbfox1/2 cooperatively enhance, and hnRNP H/F suppresses, the inclusion of human GFPT1 exon 9 by modulating recruitment of U1 snRNP. Knockout (KO) of GFPT1-L in skeletal muscle markedly increased the amounts of GFPT1 and UDP-HexNAc, which subsequently suppressed the glycolytic pathway. Aged KO mice showed impaired insulin-mediated glucose uptake, as well as muscle weakness and fatigue likely due to abnormal formation and maintenance of the neuromuscular junction. Taken together, GFPT1-L is likely to be acquired in evolution in mammalian striated muscles to attenuate the HBP for efficient glycolytic energy production, insulin-mediated glucose uptake, and the formation and maintenance of the neuromuscular junction.
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Affiliation(s)
- Paniz Farshadyeganeh
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Mohammad Nazim
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Ruchen Zhang
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Bisei Ohkawara
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Kazuki Nakajima
- Institute for Glyco-core Research (iGCORE), Gifu University, Gifu 501-1193, Japan
| | - Mohammad Alinoor Rahman
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
- Department of Biochemistry and Molecular Biology, Winthrop P. Rockefeller Cancer Institute, University of Arkansas for Medical Sciences (UAMS), Little Rock, AR 72205, USA
| | - Farhana Nasrin
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
- Department of Biochemistry and Molecular Biology, Winthrop P. Rockefeller Cancer Institute, University of Arkansas for Medical Sciences (UAMS), Little Rock, AR 72205, USA
| | - Mikako Ito
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Jun-ichi Takeda
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Kenji Ohe
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
- Faculty of Pharmaceutical Sciences, Fukuoka University, Fukuoka 814-0180, Japan
| | - Yuki Miyasaka
- Division of Experimental Animals, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Tamio Ohno
- Division of Experimental Animals, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Akio Masuda
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Kinji Ohno
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
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Bushra S, Lin YN, Joudaki A, Ito M, Ohkawara B, Ohno K, Masuda A. Neural Isoforms of Agrin Are Generated by Reduced PTBP1-RNA Interaction Network Spanning the Neuron-Specific Splicing Regions in AGRN. Int J Mol Sci 2023; 24:ijms24087420. [PMID: 37108583 PMCID: PMC10139058 DOI: 10.3390/ijms24087420] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Revised: 04/12/2023] [Accepted: 04/14/2023] [Indexed: 04/29/2023] Open
Abstract
Agrin is a heparan sulfate proteoglycan essential for the clustering of acetylcholine receptors at the neuromuscular junction. Neuron-specific isoforms of agrin are generated by alternative inclusion of three exons, called Y, Z8, and Z11 exons, although their processing mechanisms remain elusive. We found, by inspection of splicing cis-elements into the human AGRN gene, that binding sites for polypyrimidine tract binding protein 1 (PTBP1) were extensively enriched around Y and Z exons. PTBP1-silencing enhanced the coordinated inclusion of Y and Z exons in human SH-SY5Y neuronal cells, even though three constitutive exons are flanked by these alternative exons. Deletion analysis using minigenes identified five PTBP1-binding sites with remarkable splicing repression activities around Y and Z exons. Furthermore, artificial tethering experiments indicated that binding of a single PTBP1 molecule to any of these sites represses nearby Y or Z exons as well as the other distal exons. The RRM4 domain of PTBP1, which is required for looping out a target RNA segment, was likely to play a crucial role in the repression. Neuronal differentiation downregulates PTBP1 expression and promotes the coordinated inclusion of Y and Z exons. We propose that the reduction in the PTPB1-RNA network spanning these alternative exons is essential for the generation of the neuron-specific agrin isoforms.
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Affiliation(s)
- Samira Bushra
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Aichi, Japan
| | - Ying-Ni Lin
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Aichi, Japan
| | - Atefeh Joudaki
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Aichi, Japan
| | - Mikako Ito
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Aichi, Japan
| | - Bisei Ohkawara
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Aichi, Japan
| | - Kinji Ohno
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Aichi, Japan
| | - Akio Masuda
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Aichi, Japan
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Ohno K, Ohkawara B, Shen XM, Selcen D, Engel AG. Clinical and Pathologic Features of Congenital Myasthenic Syndromes Caused by 35 Genes-A Comprehensive Review. Int J Mol Sci 2023; 24:ijms24043730. [PMID: 36835142 PMCID: PMC9961056 DOI: 10.3390/ijms24043730] [Citation(s) in RCA: 26] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2023] [Revised: 02/09/2023] [Accepted: 02/09/2023] [Indexed: 02/16/2023] Open
Abstract
Congenital myasthenic syndromes (CMS) are a heterogeneous group of disorders characterized by impaired neuromuscular signal transmission due to germline pathogenic variants in genes expressed at the neuromuscular junction (NMJ). A total of 35 genes have been reported in CMS (AGRN, ALG14, ALG2, CHAT, CHD8, CHRNA1, CHRNB1, CHRND, CHRNE, CHRNG, COL13A1, COLQ, DOK7, DPAGT1, GFPT1, GMPPB, LAMA5, LAMB2, LRP4, MUSK, MYO9A, PLEC, PREPL, PURA, RAPSN, RPH3A, SCN4A, SLC18A3, SLC25A1, SLC5A7, SNAP25, SYT2, TOR1AIP1, UNC13A, VAMP1). The 35 genes can be classified into 14 groups according to the pathomechanical, clinical, and therapeutic features of CMS patients. Measurement of compound muscle action potentials elicited by repetitive nerve stimulation is required to diagnose CMS. Clinical and electrophysiological features are not sufficient to identify a defective molecule, and genetic studies are always required for accurate diagnosis. From a pharmacological point of view, cholinesterase inhibitors are effective in most groups of CMS, but are contraindicated in some groups of CMS. Similarly, ephedrine, salbutamol (albuterol), amifampridine are effective in most but not all groups of CMS. This review extensively covers pathomechanical and clinical features of CMS by citing 442 relevant articles.
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Affiliation(s)
- Kinji Ohno
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
- Correspondence: (K.O.); (A.G.E.)
| | - Bisei Ohkawara
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Xin-Ming Shen
- Department of Neurology and Neuromuscular Research Laboratory, Mayo Clinic, Rochester, MN 55905, USA
| | - Duygu Selcen
- Department of Neurology and Neuromuscular Research Laboratory, Mayo Clinic, Rochester, MN 55905, USA
| | - Andrew G. Engel
- Department of Neurology and Neuromuscular Research Laboratory, Mayo Clinic, Rochester, MN 55905, USA
- Correspondence: (K.O.); (A.G.E.)
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Rodríguez Cruz PM, Ravenscroft G, Natera D, Carr A, Manzur A, Liu WW, Vella NR, Jericó I, Gonzalez-Quereda L, Gallano P, Montalto SA, Davis MR, Lamont PJ, Laing NG, Bourque P, Nascimento A, Muntoni F, Polavarapu K, Lochmüller H, Palace J, Beeson D. A novel phenotype of AChR-deficiency syndrome with predominant facial and distal weakness resulting from the inclusion of an evolutionary alternatively-spliced exon in CHRNA1. Neuromuscul Disord 2023; 33:161-168. [PMID: 36634413 DOI: 10.1016/j.nmd.2022.12.011] [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: 07/18/2022] [Revised: 12/13/2022] [Accepted: 12/19/2022] [Indexed: 12/24/2022]
Abstract
Primary acetylcholine receptor deficiency is the most common subtype of congenital myasthenic syndrome, resulting in reduced amount of acetylcholine receptors expressed at the muscle endplate and impaired neuromuscular transmission. AChR deficiency is caused mainly by pathogenic variants in the ε-subunit of the acetylcholine receptor encoded by CHRNE, although pathogenic variants in other subunits are also seen. We report the clinical and molecular features of 13 patients from nine unrelated kinships with acetylcholine receptor deficiency harbouring the CHRNA1 variant NM_001039523.3:c.257G>A (p.Arg86His) in homozygosity or compound heterozygosity. This variant results in the inclusion of an alternatively-spliced evolutionary exon (P3A) that causes expression of a non-functional acetylcholine receptor α-subunit. We compare the clinical findings of this group to the other cases of acetylcholine receptor deficiency within our cohort. We report differences in phenotype, highlighting a predominant pattern of facial and distal weakness in adulthood, predominantly in the upper limbs, which is unusual for acetylcholine receptor deficiency syndromes, and more in keeping with slow-channel syndrome or distal myopathy. Finally, we stress the importance of including alternative exons in variant analysis to increase the probability of achieving a molecular diagnosis.
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Affiliation(s)
- Pedro M Rodríguez Cruz
- CNAG-CRG, Centro Nacional de Análisis Genómico - Centre for Genomic Regulation, Barcelona Institute of Science and Technology, Barcelona, Spain.
| | - Gianina Ravenscroft
- Harry Perkins Institute of Medical Research, Nedlands, WA, Australia; Centre of Medical Research, University of Western Australia, Nedlands, WA, Australia
| | - Daniel Natera
- Neuromuscular Unit, Hospital Sant Joan de Déu, Barcelona, Spain
| | - Aisling Carr
- Centre for Neuromuscular Diseases, UCL Queen Square Institute of Neurology, National Hospital for Neurology and Neurosurgery, Queen Square, London, UK
| | - Adnan Manzur
- Dubowitz Neuromuscular Centre, NIHR Biomedical Research Centre, UCL Great Ormond Street Institute of Child Health; Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | - Wei Wei Liu
- Neurosciences Group, Weatherall Institute of Molecular Medicine, University of Oxford, The John Radcliffe Hospital, Oxford, UK
| | - Norbert R Vella
- Department of Neuroscience, Mater Dei Hospital, Msida, Malta
| | - Ivonne Jericó
- Department of Neurology, Hospital Universitario de Navarra, IdisNa (Instituto Investigación Sanitaria Navarra), Pamplona, Spain
| | - Lidia Gonzalez-Quereda
- Center for the Biomedical Research on Rare Diseases (CIBERER), ISCIII, Madrid, Spain; Department of Genetics, Hospital de Sant Pau, IIB Sant Pau, Barcelona, Spain
| | - Pia Gallano
- Center for the Biomedical Research on Rare Diseases (CIBERER), ISCIII, Madrid, Spain; Department of Genetics, Hospital de Sant Pau, IIB Sant Pau, Barcelona, Spain
| | | | - Mark R Davis
- Neurogenetic Unit, Department of Diagnostic Genomics, PathWest Laboratory Medicine, Western Australian Department of Health, Nedlands, WA, Australia
| | - Phillipa J Lamont
- Department of Neurology, Royal Perth Hospital, Nedlands, WA, Australia
| | - Nigel G Laing
- Harry Perkins Institute of Medical Research, Nedlands, WA, Australia; Centre of Medical Research, University of Western Australia, Nedlands, WA, Australia; Neurogenetic Unit, Department of Diagnostic Genomics, PathWest Laboratory Medicine, Western Australian Department of Health, Nedlands, WA, Australia
| | - Pierre Bourque
- Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, Canada
| | | | - Francesco Muntoni
- Dubowitz Neuromuscular Centre, NIHR Biomedical Research Centre, UCL Great Ormond Street Institute of Child Health; Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | - Kiran Polavarapu
- Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, Canada
| | - Hanns Lochmüller
- CNAG-CRG, Centro Nacional de Análisis Genómico - Centre for Genomic Regulation, Barcelona Institute of Science and Technology, Barcelona, Spain; Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, Canada; Division of Neurology, Department of Medicine, The Ottawa Hospital; and Brain and Mind Research Institute, University of Ottawa, Ottawa, Canada; Department of Neuropediatrics and Muscle Disorders, Medical Center-University of Freiburg, Faculty of Medicine, Freiburg, Germany.
| | - Jacqueline Palace
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | - David Beeson
- Neurosciences Group, Weatherall Institute of Molecular Medicine, University of Oxford, The John Radcliffe Hospital, Oxford, UK; Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
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Vandermeulen C, O’Grady T, Wayet J, Galvan B, Maseko S, Cherkaoui M, Desbuleux A, Coppin G, Olivet J, Ben Ameur L, Kataoka K, Ogawa S, Hermine O, Marcais A, Thiry M, Mortreux F, Calderwood MA, Van Weyenbergh J, Peloponese JM, Charloteaux B, Van den Broeke A, Hill DE, Vidal M, Dequiedt F, Twizere JC. The HTLV-1 viral oncoproteins Tax and HBZ reprogram the cellular mRNA splicing landscape. PLoS Pathog 2021; 17:e1009919. [PMID: 34543356 PMCID: PMC8483338 DOI: 10.1371/journal.ppat.1009919] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Revised: 09/30/2021] [Accepted: 08/27/2021] [Indexed: 12/12/2022] Open
Abstract
Viral infections are known to hijack the transcription and translation of the host cell. However, the extent to which viral proteins coordinate these perturbations remains unclear. Here we used a model system, the human T-cell leukemia virus type 1 (HTLV-1), and systematically analyzed the transcriptome and interactome of key effectors oncoviral proteins Tax and HBZ. We showed that Tax and HBZ target distinct but also common transcription factors. Unexpectedly, we also uncovered a large set of interactions with RNA-binding proteins, including the U2 auxiliary factor large subunit (U2AF2), a key cellular regulator of pre-mRNA splicing. We discovered that Tax and HBZ perturb the splicing landscape by altering cassette exons in opposing manners, with Tax inducing exon inclusion while HBZ induces exon exclusion. Among Tax- and HBZ-dependent splicing changes, we identify events that are also altered in Adult T cell leukemia/lymphoma (ATLL) samples from two independent patient cohorts, and in well-known cancer census genes. Our interactome mapping approach, applicable to other viral oncogenes, has identified spliceosome perturbation as a novel mechanism coordinated by Tax and HBZ to reprogram the transcriptome. Tax and HBZ are two viral regulatory proteins encoded by the human T-cell leukemia virus type 1 (HTLV-1) via sense and antisense transcripts, respectively. Both proteins are known to drive oncogenic processes that culminate in a T-cell neoplasm, known as Adult T cell leukemia/lymphoma (ATLL). We measured the effects of Tax and HBZ on host gene expression pathway by analyzing the interactome with cellular transcriptional and post-transcriptional regulators, and the transcriptome and mRNA splicing of cell lines expressing either Tax or HBZ. We compared our results with data obtained from independent cohorts of Japanese and Afro-Caribbean patients, and identified common splicing changes that might represent clinically useful biomarkers for ATLL. Finally, we provide evidence that the viral protein Tax can reprogram initial steps of the T-cell transcriptome diversification by hijacking the U2AF complex, a key cellular regulator of pre-mRNA splicing.
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Affiliation(s)
- Charlotte Vandermeulen
- Laboratory of Viral Interactomes, GIGA Institute, University of Liege, Liege, Belgium
- Center for Cancer Systems Biology (CCSB), Dana-Farber Cancer Institute, Boston, Massachusetts, United States of America
- Laboratory of Gene Expression and Cancer, GIGA Institute, University of Liege, Liege, Belgium
| | - Tina O’Grady
- Laboratory of Gene Expression and Cancer, GIGA Institute, University of Liege, Liege, Belgium
| | - Jerome Wayet
- Unit of Animal Genomics, GIGA, Université de Liège (ULiège), Liège, Belgium
| | - Bartimee Galvan
- Laboratory of Gene Expression and Cancer, GIGA Institute, University of Liege, Liege, Belgium
| | - Sibusiso Maseko
- Laboratory of Viral Interactomes, GIGA Institute, University of Liege, Liege, Belgium
| | - Majid Cherkaoui
- Laboratory of Viral Interactomes, GIGA Institute, University of Liege, Liege, Belgium
| | - Alice Desbuleux
- Laboratory of Viral Interactomes, GIGA Institute, University of Liege, Liege, Belgium
- Center for Cancer Systems Biology (CCSB), Dana-Farber Cancer Institute, Boston, Massachusetts, United States of America
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts, United States of America
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, Massachusetts, United States of America
| | - Georges Coppin
- Laboratory of Viral Interactomes, GIGA Institute, University of Liege, Liege, Belgium
- Center for Cancer Systems Biology (CCSB), Dana-Farber Cancer Institute, Boston, Massachusetts, United States of America
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts, United States of America
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, Massachusetts, United States of America
| | - Julien Olivet
- Laboratory of Viral Interactomes, GIGA Institute, University of Liege, Liege, Belgium
- Center for Cancer Systems Biology (CCSB), Dana-Farber Cancer Institute, Boston, Massachusetts, United States of America
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts, United States of America
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, Massachusetts, United States of America
| | - Lamya Ben Ameur
- Laboratory of Biology and Modeling of the Cell, CNRS UMR 5239, INSERM U1210, University of Lyon, Lyon, France
| | - Keisuke Kataoka
- Department of Pathology and Tumor Biology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Seishi Ogawa
- Department of Pathology and Tumor Biology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Olivier Hermine
- Service Hématologie Adultes, Assistance Publique-Hôpitaux de Paris, Hôpital Necker Enfants Malades, Université de Paris, Laboratoire d’onco-hématologie, Institut Necker-Enfants Malades, INSERM U1151, Université de Paris, Paris, France
| | - Ambroise Marcais
- Service Hématologie Adultes, Assistance Publique-Hôpitaux de Paris, Hôpital Necker Enfants Malades, Université de Paris, Laboratoire d’onco-hématologie, Institut Necker-Enfants Malades, INSERM U1151, Université de Paris, Paris, France
| | - Marc Thiry
- Unit of Cell and Tissue Biology, GIGA Institute, University of Liege, Liege, Belgium
| | - Franck Mortreux
- Laboratory of Biology and Modeling of the Cell, CNRS UMR 5239, INSERM U1210, University of Lyon, Lyon, France
| | - Michael A. Calderwood
- Center for Cancer Systems Biology (CCSB), Dana-Farber Cancer Institute, Boston, Massachusetts, United States of America
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts, United States of America
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, Massachusetts, United States of America
| | - Johan Van Weyenbergh
- Laboratory of Clinical and Epidemiological Virology, Rega Institute for Medical Research, Department of Microbiology, Immunology and Transplantation, Catholic University of Leuven, Leuven, Belgium
| | | | - Benoit Charloteaux
- Center for Cancer Systems Biology (CCSB), Dana-Farber Cancer Institute, Boston, Massachusetts, United States of America
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts, United States of America
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, Massachusetts, United States of America
- Department of Human Genetics, CHU of Liege, University of Liege, Liege, Belgium
| | - Anne Van den Broeke
- Unit of Animal Genomics, GIGA, Université de Liège (ULiège), Liège, Belgium
- Laboratory of Experimental Hematology, Institut Jules Bordet, Université Libre de Bruxelles (ULB), Brussels, Belgium
- * E-mail: (AVdB); (DEH); (MV); (FD); (J-CT)
| | - David E. Hill
- Center for Cancer Systems Biology (CCSB), Dana-Farber Cancer Institute, Boston, Massachusetts, United States of America
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts, United States of America
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, Massachusetts, United States of America
- * E-mail: (AVdB); (DEH); (MV); (FD); (J-CT)
| | - Marc Vidal
- Center for Cancer Systems Biology (CCSB), Dana-Farber Cancer Institute, Boston, Massachusetts, United States of America
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts, United States of America
- * E-mail: (AVdB); (DEH); (MV); (FD); (J-CT)
| | - Franck Dequiedt
- Laboratory of Gene Expression and Cancer, GIGA Institute, University of Liege, Liege, Belgium
- * E-mail: (AVdB); (DEH); (MV); (FD); (J-CT)
| | - Jean-Claude Twizere
- Laboratory of Viral Interactomes, GIGA Institute, University of Liege, Liege, Belgium
- Center for Cancer Systems Biology (CCSB), Dana-Farber Cancer Institute, Boston, Massachusetts, United States of America
- * E-mail: (AVdB); (DEH); (MV); (FD); (J-CT)
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10
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Luo X, Jean-Toussaint R, Sacan A, Ajit SK. Differential RNA packaging into small extracellular vesicles by neurons and astrocytes. Cell Commun Signal 2021; 19:75. [PMID: 34246289 PMCID: PMC8272329 DOI: 10.1186/s12964-021-00757-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2021] [Accepted: 06/03/2021] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND Small extracellular vesicles (sEVs) mediate intercellular communication by transferring RNA, proteins, and lipids to recipient cells. These cargo molecules are selectively loaded into sEVs and mirror the physiological state of the donor cells. Given that sEVs can cross the blood-brain barrier and their composition can change in neurological disorders, the molecular signatures of sEVs in circulation can be potential disease biomarkers. Characterizing the molecular composition of sEVs from different cell types is an important first step in determining which donor cells contribute to the circulating sEVs. METHODS Cell culture supernatants from primary mouse cortical neurons and astrocytes were used to purify sEVs by differential ultracentrifugation and sEVs were characterized using nanoparticle tracking analysis, transmission electron microscopy and western blot. RNA sequencing was used to determine differential expression and loading patterns of miRNAs in sEVs released by primary neurons and astrocytes. Motif analysis was conducted on enriched miRNAs in sEVs and their respective donor cells. RESULTS Sequencing total cellular RNA, and miRNAs from sEVs isolated from culture media of postnatal mouse cortical neurons and astrocytes revealed a distinct profile between sEVs and their corresponding cells. Though the total number of detected miRNAs in astrocytes was greater than neurons, neurons expressed more sEV-associated miRNAs than astrocytes. Only 20.7% of astrocytic miRNAs were loaded into sEVs, while 41.0% of neuronal miRNAs were loaded into sEVs, suggesting differences in the cellular sorting mechanisms. We identified short RNA sequence motifs, or EXOmotifs, on the miRNAs that were differentially loaded or excluded from sEVs. A sequence motif GUAC was enriched in astrocytic sEVs. miRNAs preferably retained in neurons or astrocytes had a similar RNA motif CACACA, suggesting a cell-type-independent mechanism to maintain cellular miRNAs. mRNAs of five RNA-binding proteins associated with passive or active RNA sorting into sEVs were differentially expressed between neurons and astrocytes, one of which, major vault protein was higher in astrocytes than in neurons and detected in astrocytic sEVs. CONCLUSIONS Our studies suggest differences in RNA sorting into sEVs. These differences in miRNA signatures can be used for determining the cellular sources of sEVs altered in neurological disorders. Video abstract.
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Affiliation(s)
- Xuan Luo
- Department of Pharmacology and Physiology, Drexel University College of Medicine, 245 North 15th Street, Philadelphia, PA 19102 USA
| | - Renée Jean-Toussaint
- Department of Pharmacology and Physiology, Drexel University College of Medicine, 245 North 15th Street, Philadelphia, PA 19102 USA
| | - Ahmet Sacan
- School of Biomedical Engineering, Science and Health Systems, Drexel University, 3141 Chestnut Street, Philadelphia, PA 19104 USA
| | - Seena K. Ajit
- Department of Pharmacology and Physiology, Drexel University College of Medicine, 245 North 15th Street, Philadelphia, PA 19102 USA
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11
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The methyltransferase SETD2 couples transcription and splicing by engaging mRNA processing factors through its SHI domain. Nat Commun 2021; 12:1443. [PMID: 33664260 PMCID: PMC7933334 DOI: 10.1038/s41467-021-21663-w] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Accepted: 02/04/2021] [Indexed: 12/13/2022] Open
Abstract
Heterogeneous ribonucleoproteins (hnRNPs) are RNA binding molecules that are involved in key processes such as RNA splicing and transcription. One such hnRNP protein, hnRNP L, regulates alternative splicing (AS) by binding to pre-mRNA transcripts. However, it is unclear what factors contribute to hnRNP L-regulated AS events. Using proteomic approaches, we identified several key factors that co-purify with hnRNP L. We demonstrate that one such factor, the histone methyltransferase SETD2, specifically interacts with hnRNP L in vitro and in vivo. This interaction occurs through a previously uncharacterized domain in SETD2, the SETD2-hnRNP Interaction (SHI) domain, the deletion of which, leads to a reduced H3K36me3 deposition. Functionally, SETD2 regulates a subset of hnRNP L-targeted AS events. Our findings demonstrate that SETD2, by interacting with Pol II as well as hnRNP L, can mediate the crosstalk between the transcription and the splicing machinery. The methylation of Histone 3 at Lysine 36 (H3K36) has been implicated in the regulation of transcription and coupled processes such as mRNA splicing. Here the authors show that the histone methyltransferase SETD2 interacts with hnRNP L to mediate the crosstalk between the transcription and splicing machineries.
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12
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Frederiksen SB, Holm LL, Larsen MR, Doktor TK, Andersen HS, Hastings ML, Hua Y, Krainer AR, Andresen BS. Identification of SRSF10 as a regulator of SMN2 ISS-N1. Hum Mutat 2020; 42:246-260. [PMID: 33300159 DOI: 10.1002/humu.24149] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Revised: 10/22/2020] [Accepted: 12/06/2020] [Indexed: 01/02/2023]
Abstract
Understanding the splicing code can be challenging as several splicing factors bind to many splicing-regulatory elements. The SMN1 and SMN2 silencer element ISS-N1 is the target of the antisense oligonucleotide drug, Spinraza, which is the treatment against spinal muscular atrophy. However, limited knowledge about the nature of the splicing factors that bind to ISS-N1 and inhibit splicing exists. It is likely that the effect of Spinraza comes from blocking binding of these factors, but so far, an unbiased characterization has not been performed and only members of the hnRNP A1/A2 family have been identified by Western blot analysis and nuclear magnetic resonance to bind to this silencer. Employing an MS/MS-based approach and surface plasmon resonance imaging, we show for the first time that splicing factor SRSF10 binds to ISS-N1. Furthermore, using splice-switching oligonucleotides we modulated the splicing of the SRSF10 isoforms generating either the long or the short protein isoform of SRSF10 to regulate endogenous SMN2 exon 7 inclusion. We demonstrate that the isoforms of SRSF10 regulate SMN1 and SMN2 splicing with different strength correlating with the length of their RS domain. Our results suggest that the ratio between the SRSF10 isoforms is important for splicing regulation.
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Affiliation(s)
- Sabrina B Frederiksen
- Department of Biochemistry and Molecular Biology and the Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense M, Denmark
| | - Lise L Holm
- Department of Biochemistry and Molecular Biology and the Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense M, Denmark
| | - Martin R Larsen
- Department of Biochemistry and Molecular Biology and the Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense M, Denmark
| | - Thomas K Doktor
- Department of Biochemistry and Molecular Biology and the Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense M, Denmark
| | - Henriette S Andersen
- Department of Biochemistry and Molecular Biology and the Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense M, Denmark
| | - Michelle L Hastings
- Department of Cell Biology and Anatomy, Center for Genetic Diseases, Chicago Medical School and School of Graduate and Postdoctoral Studies, Rosalind Franklin University of Medicine and Science, North Chicago, Illinois, USA
| | - Yimin Hua
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, USA
| | - Adrian R Krainer
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, USA
| | - Brage S Andresen
- Department of Biochemistry and Molecular Biology and the Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense M, Denmark
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13
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Ricciardi L, Giurato G, Memoli D, Pietrafesa M, Dal Col J, Salvato I, Nigro A, Vatrella A, Caramori G, Casolaro V, Stellato C. Posttranscriptional Gene Regulatory Networks in Chronic Airway Inflammatory Diseases: In silico Mapping of RNA-Binding Protein Expression in Airway Epithelium. Front Immunol 2020; 11:579889. [PMID: 33178205 PMCID: PMC7596416 DOI: 10.3389/fimmu.2020.579889] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Accepted: 08/19/2020] [Indexed: 12/20/2022] Open
Abstract
Background: Posttranscriptional gene regulation (PTGR) contributes to inflammation through alterations in messenger RNA (mRNA) turnover and translation rates. RNA-binding proteins (RBPs) coordinate these processes but their role in lung inflammatory diseases is ill-defined. We evaluated the expression of a curated list of mRNA-binding RBPs (mRBPs) in selected Gene Expression Omnibus (GEO) transcriptomic databases of airway epithelium isolated from chronic obstructive pulmonary disease (COPD), severe asthma (SA) and matched control subjects, hypothesizing that global changes in mRBPs expression could be used to infer their pathogenetic roles and identify novel disease-related regulatory networks. Methods: A published list of 692 mRBPs [Nat Rev Genet 2014] was searched in GEO datasets originated from bronchial brushings of stable COPD patients (C), smokers (S), non-smokers (NS) controls with normal lung function (n = 6/12/12) (GEO ID: GSE5058) and of (SA) and healthy control (HC) (n = 6/12) (GSE63142). Fluorescence intensity data were extracted and normalized on the medians for fold change (FC) comparisons. FCs were set at ≥ |1.5| with a false discovery rate (FDR) of ≤ 0.05. Pearson correlation maps and heatmaps were generated using tMEV tools v4_9_0.45. DNA sequence motifs were searched using PScan-ChIP. Gene Ontology (GO) was performed with Ingenuity Pathway Analysis (IPA) tool. Results: Significant mRBP expression changes were detected for S/NS, COPD/NS and COPD/S (n = 41, 391, 382, respectively). Of those, 32% of genes changed by FC ≥ |1.5| in S/NS but more than 60% in COPD/NS and COPD/S (n = 13, 267, 257, respectively). Genes were predominantly downregulated in COPD/NS (n = 194, 73%) and COPD/S (n = 202, 79%), less so in S/NS (n = 4, 31%). Unsupervised cluster analysis identified in 4 out of 12 S the same mRBP pattern seen in C, postulating subclinical COPD. Significant DNA motifs enrichment for transcriptional regulation was found for downregulated RBPs. Correlation analysis identified five clusters of co-expressed mRBPs. GO analysis revealed significant enrichments in canonical pathways both specific and shared among comparisons. Unexpectedly, no significant mRBPs modulation was found in SA compared to controls. Conclusions: Airway epithelial mRBPs profiling reveals a COPD-specific global downregulation of RBPs shared by a subset of control smokers, the potential of functional cooperation by coexpressed RBPs and significant impact on relevant pathogenetic pathways in COPD. Elucidation of PTGR in COPD could identify disease biomarkers or pathways for therapeutic targeting.
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Affiliation(s)
- Luca Ricciardi
- Department of Medicine, Surgery and Dentistry Scuola Medica Salernitana, University of Salerno, Salerno, Italy
| | - Giorgio Giurato
- Department of Medicine, Surgery and Dentistry Scuola Medica Salernitana, University of Salerno, Salerno, Italy
| | - Domenico Memoli
- Department of Medicine, Surgery and Dentistry Scuola Medica Salernitana, University of Salerno, Salerno, Italy
| | - Mariagrazia Pietrafesa
- Department of Medicine, Surgery and Dentistry Scuola Medica Salernitana, University of Salerno, Salerno, Italy
| | - Jessica Dal Col
- Department of Medicine, Surgery and Dentistry Scuola Medica Salernitana, University of Salerno, Salerno, Italy
| | - Ilaria Salvato
- Pulmonology, Department of Biomedical Sciences, Dentistry and Morphological and Functional Imaging (BIOMORF), University of Messina, Messina, Italy
| | - Annunziata Nigro
- Department of Medicine, Surgery and Dentistry Scuola Medica Salernitana, University of Salerno, Salerno, Italy
| | - Alessandro Vatrella
- Department of Medicine, Surgery and Dentistry Scuola Medica Salernitana, University of Salerno, Salerno, Italy
| | - Gaetano Caramori
- Pulmonology, Department of Biomedical Sciences, Dentistry and Morphological and Functional Imaging (BIOMORF), University of Messina, Messina, Italy
| | - Vincenzo Casolaro
- Department of Medicine, Surgery and Dentistry Scuola Medica Salernitana, University of Salerno, Salerno, Italy.,Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Cristiana Stellato
- Department of Medicine, Surgery and Dentistry Scuola Medica Salernitana, University of Salerno, Salerno, Italy.,Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, United States
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14
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Low YH, Asi Y, Foti SC, Lashley T. Heterogeneous Nuclear Ribonucleoproteins: Implications in Neurological Diseases. Mol Neurobiol 2020; 58:631-646. [PMID: 33000450 PMCID: PMC7843550 DOI: 10.1007/s12035-020-02137-4] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Accepted: 09/17/2020] [Indexed: 12/13/2022]
Abstract
Heterogenous nuclear ribonucleoproteins (hnRNPs) are a complex and functionally diverse family of RNA binding proteins with multifarious roles. They are involved, directly or indirectly, in alternative splicing, transcriptional and translational regulation, stress granule formation, cell cycle regulation, and axonal transport. It is unsurprising, given their heavy involvement in maintaining functional integrity of the cell, that their dysfunction has neurological implications. However, compared to their more established roles in cancer, the evidence of hnRNP implication in neurological diseases is still in its infancy. This review aims to consolidate the evidences for hnRNP involvement in neurological diseases, with a focus on spinal muscular atrophy (SMA), Alzheimer’s disease (AD), amyotrophic lateral sclerosis (ALS), frontotemporal dementia (FTD), multiple sclerosis (MS), congenital myasthenic syndrome (CMS), and fragile X-associated tremor/ataxia syndrome (FXTAS). Understanding more about hnRNP involvement in neurological diseases can further elucidate the pathomechanisms involved in these diseases and perhaps guide future therapeutic advances.
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Affiliation(s)
- Yi-Hua Low
- The Queen Square Brain Bank for Neurological Disorders, Department of Clinical and Movement Disorders, UCL Queen Square Institute of Neurology, University College London, London, WC1N 3BG, UK.,Duke-NUS Medical School, Singapore, Singapore
| | - Yasmine Asi
- The Queen Square Brain Bank for Neurological Disorders, Department of Clinical and Movement Disorders, UCL Queen Square Institute of Neurology, University College London, London, WC1N 3BG, UK
| | - Sandrine C Foti
- The Queen Square Brain Bank for Neurological Disorders, Department of Clinical and Movement Disorders, UCL Queen Square Institute of Neurology, University College London, London, WC1N 3BG, UK.,Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, University College London, London, UK
| | - Tammaryn Lashley
- The Queen Square Brain Bank for Neurological Disorders, Department of Clinical and Movement Disorders, UCL Queen Square Institute of Neurology, University College London, London, WC1N 3BG, UK. .,Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, University College London, London, UK.
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15
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Sternburg EL, Karginov FV. Global Approaches in Studying RNA-Binding Protein Interaction Networks. Trends Biochem Sci 2020; 45:593-603. [DOI: 10.1016/j.tibs.2020.03.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Revised: 02/28/2020] [Accepted: 03/09/2020] [Indexed: 12/24/2022]
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16
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Abstract
The family of heterogeneous ribonucleoproteins (hnRNPs) have multiple functions in RNA metabolism. In recent years, several hnRNPs have also been shown to be essential for the maintenance of transcriptome integrity, by preventing intronic cryptic splicing signals from mis-splicing of many endogeneous pre-mRNA transcripts. Here we discuss the possibility for a general role of this family of proteins and their expansion in transcriptome protection.
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Affiliation(s)
- Urmi Das
- a Department of Physiology & Pathophysiology, Max Rady College of Medicine, Rady Faculty of Health Sciences , University of Manitoba , Winnipeg , Canada
| | - Hai Nguyen
- a Department of Physiology & Pathophysiology, Max Rady College of Medicine, Rady Faculty of Health Sciences , University of Manitoba , Winnipeg , Canada.,b Department of Applied Computer Science , University of Winnipeg , Winnipeg , Canada
| | - Jiuyong Xie
- a Department of Physiology & Pathophysiology, Max Rady College of Medicine, Rady Faculty of Health Sciences , University of Manitoba , Winnipeg , Canada
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17
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Pina JM, Reynaga JM, Truong AAM, Keppetipola NM. Post-Translational Modifications in Polypyrimidine Tract Binding Proteins PTBP1 and PTBP2. Biochemistry 2018; 57:3873-3882. [PMID: 29851470 PMCID: PMC6211845 DOI: 10.1021/acs.biochem.8b00256] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
RNA binding proteins play an important role in regulating alternative pre-mRNA splicing and in turn cellular gene expression. Many of these RNA binding proteins occur as gene families with members sharing a high degree of primary structure identity and domain organization yet have tissue-specific expression patterns and regulate different sets of target exons. How highly similar members in a gene family can exert different splicing outcomes is not well understood. We conducted mass spectrometry analysis of post-translational phosphorylation and acetylation modifications for two paralogs of the polypyrimidine tract binding protein family, PTBP1 and PTBP2, to discover modifications that occur in splicing reaction mixtures and to identify discrete modifications that may direct their different splicing activities. We find that PTBP1 and PTBP2 have many distinct phosphate modifications located in the unstructured N-terminal, linker 1, and linker 2 regions. We find that the two proteins have many overlapping acetate modifications in the RNA recognition motifs (RRMs) with a few distinct sites in PTBP1 RRM2 and RRM3. Our data also reveal that lysine residues in the nuclear localization sequence of PTBP2 are acetylated. Collectively, our results highlight important differences in post-translational modifications between the paralogs and suggest a role for them in the differential splicing activity of PTBP1 and PTBP2.
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Affiliation(s)
- Jeffrey M. Pina
- Department of Chemistry and Biochemistry, California State University, Fullerton, 800 North State College Boulevard, Fullerton, California 92831, United States
| | - Janice M. Reynaga
- Department of Chemistry and Biochemistry, California State University, Fullerton, 800 North State College Boulevard, Fullerton, California 92831, United States
| | - Anthony A. M. Truong
- Department of Chemistry and Biochemistry, California State University, Fullerton, 800 North State College Boulevard, Fullerton, California 92831, United States
| | - Niroshika M. Keppetipola
- Department of Chemistry and Biochemistry, California State University, Fullerton, 800 North State College Boulevard, Fullerton, California 92831, United States
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18
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Multilevel Differential Control of Hormone Gene Expression Programs by hnRNP L and LL in Pituitary Cells. Mol Cell Biol 2018; 38:MCB.00651-17. [PMID: 29610151 PMCID: PMC5974433 DOI: 10.1128/mcb.00651-17] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Accepted: 03/22/2018] [Indexed: 12/20/2022] Open
Abstract
The pituitary-derived somatolactotrophe GH3 cells secrete both growth hormone (GH) and prolactin (PRL). We have found that the hnRNP L and L-like (LL) paralogs differentially regulate alternative splicing of genes in these cells. Here, we show that hnRNP L is essential for PRL only, but LL is essential for both PRL and GH production. Transcriptome-wide RNA sequencing (RNA-Seq) analysis indicates that they differentially control groups of hormone or hormone-related genes involved in hormone production/regulation at total transcript and alternative exon levels. Interestingly, hnRNP L also specifically binds and prevents the aberrant usage of a nonconserved CA-rich intron piece of Prl pre-mRNA transcripts, and many others involved in endocrine functions, to prevent mostly cryptic last exons and mRNA truncation. Essential for the full hnRNP L effect on specific exons is a proline-rich region that emerged during evolution in vertebrate hnRNP L only but not LL. Together, our data demonstrate that the hnRNP L and its paralog, LL, differentially control hormone gene expression programs at multiple levels, and hnRNP L in particular is critical for protecting the transcriptome from aberrant usage of intronic sequences. The multilevel differential control by hnRNPs likely tailors the transcriptome to help refine and safeguard the different gene expression programs for different hormones.
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Dassi E. Handshakes and Fights: The Regulatory Interplay of RNA-Binding Proteins. Front Mol Biosci 2017; 4:67. [PMID: 29034245 PMCID: PMC5626838 DOI: 10.3389/fmolb.2017.00067] [Citation(s) in RCA: 91] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Accepted: 09/20/2017] [Indexed: 12/31/2022] Open
Abstract
What drives the flow of signals controlling the outcome of post-transcriptional regulation of gene expression? This regulatory layer, presiding to processes ranging from splicing to mRNA stability and localization, is a key determinant of protein levels and thus cell phenotypes. RNA-binding proteins (RBPs) form a remarkable army of post-transcriptional regulators, strong of more than 1,500 genes implementing this expression fine-tuning plan and implicated in both cell physiology and pathology. RBPs can bind and control a wide array of RNA targets. This sheer amount of interactions form complex regulatory networks (PTRNs) where the action of individual RBPs cannot be easily untangled from each other. While past studies have mostly focused on the action of individual RBPs on their targets, we are now observing an increasing amount of evidence describing the occurrence of interactions between RBPs, defining how common target RNAs are regulated. This suggests that the flow of signals in PTRNs is driven by the intertwined contribution of multiple RBPs, concurrently acting on each of their targets. Understanding how RBPs cooperate and compete is thus of paramount importance to chart the wiring of PTRNs and their impact on cell phenotypes. Here we review the current knowledge about patterns of RBP interaction and attempt at describing their general principles. We also discuss future directions which should be taken to reach a comprehensive understanding of this fundamental aspect of gene expression regulation.
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Affiliation(s)
- Erik Dassi
- Centre for Integrative Biology, University of Trento, Trento, Italy
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20
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Ohno K, Takeda JI, Masuda A. Rules and tools to predict the splicing effects of exonic and intronic mutations. WILEY INTERDISCIPLINARY REVIEWS-RNA 2017; 9. [DOI: 10.1002/wrna.1451] [Citation(s) in RCA: 71] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2017] [Revised: 08/23/2017] [Accepted: 08/24/2017] [Indexed: 12/14/2022]
Affiliation(s)
- Kinji Ohno
- Division of Neurogenetics, Center for Neurological Diseases and Cancer; Nagoya University Graduate School of Medicine; Nagoya Japan
| | - Jun-ichi Takeda
- Division of Neurogenetics, Center for Neurological Diseases and Cancer; Nagoya University Graduate School of Medicine; Nagoya Japan
| | - Akio Masuda
- Division of Neurogenetics, Center for Neurological Diseases and Cancer; Nagoya University Graduate School of Medicine; Nagoya Japan
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21
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Lv D, Wu H, Xing R, Shu F, Lei B, Lei C, Zhou X, Wan B, Yang Y, Zhong L, Mao X, Zou Y. HnRNP-L mediates bladder cancer progression by inhibiting apoptotic signaling and enhancing MAPK signaling pathways. Oncotarget 2017; 8:13586-13599. [PMID: 28088793 PMCID: PMC5355122 DOI: 10.18632/oncotarget.14600] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Accepted: 01/03/2017] [Indexed: 12/28/2022] Open
Abstract
Heterogeneous nuclear ribonucleoprotein L (hnRNP-L) is a promoter of various kinds of cancers, but its actions in bladder cancer (BC) are unclear. In this study, we investigated the function and the underlying mechanism of hnRNP-L in bladder carcinogenesis. Our results demonstrated that enhanced hnRNP-L expression in BC tissues was associated with poor overall survival of BC patients. Depletion of hnRNP-L significantly suppressed cell proliferation in vitro and inhibited xenograft tumor growth in vivo. Furthermore, downregulation of hnRNP-L resulted in G1-phase cell cycle arrest and enhanced apoptosis accompanied by inhibition of EMT and cell migration. All these cellular changes were reversed by ectopic expression of hnRNP-L. Deletion of hnRNP-L resulted in decreased expression of Bcl-2, enhanced expression of caspases-3, -6 and -9 and inhibition of the MAPK signaling pathway. These findings demonstrate that hnRNP-L contributes to poor prognosis and tumor progression of BC by inhibiting the intrinsic apoptotic signaling and enhancing MAPK signaling pathways.
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Affiliation(s)
- Daojun Lv
- Department of Urology, Nanfang Hospital, Southern Medical University, Guangzhou 510515, P. R. China
| | - Huayan Wu
- Department of Urology, Nanfang Hospital, Southern Medical University, Guangzhou 510515, P. R. China
| | - Rongwei Xing
- Department of Urology, Affiliated Weihai Second Municipal Hospital of Qingdao University, Weihai 264200, P. R. China
| | - Fangpeng Shu
- Department of Urology, Nanfang Hospital, Southern Medical University, Guangzhou 510515, P. R. China
| | - Bin Lei
- Department of Urology, Nanfang Hospital, Southern Medical University, Guangzhou 510515, P. R. China
| | - Chengyong Lei
- Department of Urology, Nanfang Hospital, Southern Medical University, Guangzhou 510515, P. R. China
| | - Xumin Zhou
- Department of Urology, Nanfang Hospital, Southern Medical University, Guangzhou 510515, P. R. China
| | - Bo Wan
- Department of Urology, Nanfang Hospital, Southern Medical University, Guangzhou 510515, P. R. China
| | - Yu Yang
- Department of Urology, Peking University Shenzhen Hospital, Shenzhen PKU-HKUST Medical Center, Shenzhen, Guangdong Province, 518036, China
| | - Liren Zhong
- Department of Urology, Nanfang Hospital, Southern Medical University, Guangzhou 510515, P. R. China
| | - Xiangming Mao
- Department of Urology, Nanfang Hospital, Southern Medical University, Guangzhou 510515, P. R. China.,Department of Urology, Peking University Shenzhen Hospital, Shenzhen PKU-HKUST Medical Center, Shenzhen, Guangdong Province, 518036, China
| | - Yaguang Zou
- Department of Stomatology, Nanfang Hospital, Southern Medical University, Guangzhou 510515, P. R. China
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22
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SRSF1 suppresses selection of intron-distal 5' splice site of DOK7 intron 4 to generate functional full-length Dok-7 protein. Sci Rep 2017; 7:10446. [PMID: 28874828 PMCID: PMC5585400 DOI: 10.1038/s41598-017-11036-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Accepted: 08/18/2017] [Indexed: 01/23/2023] Open
Abstract
Dok-7 is a non-catalytic adaptor protein that facilitates agrin-induced clustering of acetylcholine receptors (AChR) at the neuromuscular junction. Alternative selection of 5′ splice sites (SSs) of DOK7 intron 4 generates canonical and frame-shifted transcripts. We found that the canonical full-length Dok-7 enhanced AChR clustering, whereas the truncated Dok-7 did not. We identified a splicing cis-element close to the 3′ end of exon 4 by block-scanning mutagenesis. RNA affinity purification and mass spectrometry revealed that SRSF1 binds to the cis-element. Knocking down of SRSF1 enhanced selection of the intron-distal 5′ SS of DOK7 intron 4, whereas MS2-mediated artificial tethering of SRSF1 to the identified cis-element suppressed it. Isolation of an early spliceosomal complex revealed that SRSF1 inhibited association of U1 snRNP to the intron-distal 5′ SS, and rather enhanced association of U1 snRNP to the intron-proximal 5′ SS, which led to upregulation of the canonical DOK7 transcript. Integrated global analysis of CLIP-seq and RNA-seq also indicated that binding of SRSF1 immediately upstream to two competing 5′ SSs suppresses selection of the intron-distal 5′ SS in hundreds of human genes. We demonstrate that SRSF1 critically regulates alternative selection of adjacently placed 5′ SSs by modulating binding of U1 snRNP.
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23
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Ohno K, Rahman MA, Nazim M, Nasrin F, Lin Y, Takeda JI, Masuda A. Splicing regulation and dysregulation of cholinergic genes expressed at the neuromuscular junction. J Neurochem 2017; 142 Suppl 2:64-72. [PMID: 28072465 DOI: 10.1111/jnc.13954] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Revised: 12/23/2016] [Accepted: 01/02/2017] [Indexed: 02/05/2023]
Abstract
We humans have evolved by acquiring diversity of alternative RNA metabolisms including alternative means of splicing and transcribing non-coding genes, and not by acquiring new coding genes. Tissue-specific and developmental stage-specific alternative RNA splicing is achieved by tightly regulated spatiotemporal regulation of expressions and activations of RNA-binding proteins that recognize their cognate splicing cis-elements on nascent RNA transcripts. Genes expressed at the neuromuscular junction are also alternatively spliced. In addition, germline mutations provoke aberrant splicing by compromising binding of RNA-binding proteins, and cause congenital myasthenic syndromes (CMS). We present physiological splicing mechanisms of genes for agrin (AGRN), acetylcholinesterase (ACHE), MuSK (MUSK), acetylcholine receptor (AChR) α1 subunit (CHRNA1), and collagen Q (COLQ) in human, and their aberration in diseases. Splicing isoforms of AChET , AChEH , and AChER are generated by hnRNP H/F. Skipping of MUSK exon 10 makes a Wnt-insensitive MuSK isoform, which is unique to human. Skipping of exon 10 is achieved by coordinated binding of hnRNP C, YB-1, and hnRNP L to exon 10. Exon P3A of CHRNA1 is alternatively included to generate a non-functional AChR α1 subunit in human. Molecular dissection of splicing mutations in patients with CMS reveals that exon P3A is alternatively skipped by hnRNP H, polypyrimidine tract-binding protein 1, and hnRNP L. Similarly, analysis of an exonic mutation in COLQ exon 16 in a CMS patient discloses that constitutive splicing of exon 16 requires binding of serine arginine-rich splicing factor 1. Intronic and exonic splicing mutations in CMS enable us to dissect molecular mechanisms underlying alternative and constitutive splicing of genes expressed at the neuromuscular junction. This is an article for the special issue XVth International Symposium on Cholinergic Mechanisms.
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Affiliation(s)
- Kinji Ohno
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Mohammad Alinoor Rahman
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Mohammad Nazim
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Farhana Nasrin
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Yingni Lin
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Jun-Ichi Takeda
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Akio Masuda
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya, Japan
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Loh TJ, Choi N, Moon H, Jang HN, Liu Y, Zhou J, Zheng X, Shen H. Suppression of 5' splice-sites through multiple exonic motifs by hnRNP L. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2017; 1860:363-373. [PMID: 28119102 DOI: 10.1016/j.bbagrm.2017.01.010] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Revised: 01/20/2017] [Accepted: 01/20/2017] [Indexed: 10/20/2022]
Abstract
Selection of 5' splice-sites (5'SS) in alternative splicing plays an important role in gene regulation. Although regulatory mechanisms of heterogeneous nuclear ribonucleoprotein L (hnRNP L), a well-known splicing regulatory protein, have been studied in a substantial level, its role in 5'SS selection is not thoroughly defined. By using a KLF6 pre-mRNA alternative splicing model, we demonstrate in this report that hnRNP L inhibits proximal 5'SS but promotes two consecutive distal 5'SS splicing, antagonizing SRSF1 roles in KLF6 pre-mRNA splicing. In addition, three consecutive CA-rich sequences in a CA cassette immediately upstream of the proximal 5'SS are all required for hnRNP L functions. Importantly, the CA-cassette locations on the proximal exon do not affect hnRNP L roles. We further show that the proximal 5'SS but not the two distal 5'SSs are essential for hnRNP L activities. Notably, in a Bcl-x pre-mRNA model that contains two alternative 5'SS but includes CA-rich elements at distal exon, we demonstrate that hnRNP L also suppresses nearby 5'SS activation. Taken together, we conclude that hnRNP L suppresses 5'SS selection through multiple exonic motifs.
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Affiliation(s)
- Tiing Jen Loh
- School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju 500-712, Republic of Korea
| | - Namjeong Choi
- School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju 500-712, Republic of Korea
| | - Heegyum Moon
- School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju 500-712, Republic of Korea
| | - Ha Na Jang
- School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju 500-712, Republic of Korea
| | - Yongchao Liu
- School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju 500-712, Republic of Korea
| | - Jianhua Zhou
- Jiangsu Key Laboratory of Neuroregeneration, Nantong University, Nantong, China
| | - Xuexiu Zheng
- School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju 500-712, Republic of Korea.
| | - Haihong Shen
- School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju 500-712, Republic of Korea.
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25
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Hillebrand F, Peter JO, Brillen AL, Otte M, Schaal H, Erkelenz S. Differential hnRNP D isoform incorporation may confer plasticity to the ESSV-mediated repressive state across HIV-1 exon 3. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2016; 1860:205-217. [PMID: 27919832 DOI: 10.1016/j.bbagrm.2016.12.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2016] [Revised: 11/22/2016] [Accepted: 12/01/2016] [Indexed: 11/27/2022]
Abstract
Even though splicing repression by hnRNP complexes bound to exonic sequences is well-documented, the responsible effector domains of hnRNP proteins have been described for only a select number of hnRNP constituents. Thus, there is only limited information available for possible varying silencer activities amongst different hnRNP proteins and composition changes within possible hnRNP complex assemblies. In this study, we identified the glycine-rich domain (GRD) of hnRNP proteins as a unifying feature in splice site repression. We also show that all four hnRNP D isoforms can act as genuine splicing repressors when bound to exonic positions. The presence of an extended GRD, however, seemed to potentiate the hnRNP D silencer activity of isoforms p42 and p45. Moreover, we demonstrate that hnRNP D proteins associate with the HIV-1 ESSV silencer complex, probably through direct recognition of "UUAG" sequences overlapping with the previously described "UAGG" motifs bound by hnRNP A1. Consequently, this spatial proximity seems to cause mutual interference between hnRNP A1 and hnRNP D. This interplay between hnRNP A1 and D facilitates a dynamic regulation of the repressive state of HIV-1 exon 3 which manifests as fluctuating relative levels of spliced vpr- and unspliced gag/pol-mRNAs.
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Affiliation(s)
- Frank Hillebrand
- Institute of Virology, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany
| | - Jan Otto Peter
- Institute of Virology, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany
| | - Anna-Lena Brillen
- Institute of Virology, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany
| | - Marianne Otte
- Institute of Evolutionary Genetics, Heinrich-Heine-University Duesseldorf, Duesseldorf, Germany
| | - Heiner Schaal
- Institute of Virology, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany
| | - Steffen Erkelenz
- Institute of Virology, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany; Institute for Genetics and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany.
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26
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Nonlethal CHRNA1-Related Congenital Myasthenic Syndrome with a Homozygous Null Mutation. Can J Neurol Sci 2016; 44:125-127. [PMID: 27748205 DOI: 10.1017/cjn.2016.322] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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27
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Ferreira PG, Oti M, Barann M, Wieland T, Ezquina S, Friedländer MR, Rivas MA, Esteve-Codina A, Rosenstiel P, Strom TM, Lappalainen T, Guigó R, Sammeth M. Sequence variation between 462 human individuals fine-tunes functional sites of RNA processing. Sci Rep 2016; 6:32406. [PMID: 27617755 PMCID: PMC5019111 DOI: 10.1038/srep32406] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2016] [Accepted: 08/03/2016] [Indexed: 12/23/2022] Open
Abstract
Recent advances in the cost-efficiency of sequencing technologies enabled the combined DNA- and RNA-sequencing of human individuals at the population-scale, making genome-wide investigations of the inter-individual genetic impact on gene expression viable. Employing mRNA-sequencing data from the Geuvadis Project and genome sequencing data from the 1000 Genomes Project we show that the computational analysis of DNA sequences around splice sites and poly-A signals is able to explain several observations in the phenotype data. In contrast to widespread assessments of statistically significant associations between DNA polymorphisms and quantitative traits, we developed a computational tool to pinpoint the molecular mechanisms by which genetic markers drive variation in RNA-processing, cataloguing and classifying alleles that change the affinity of core RNA elements to their recognizing factors. The in silico models we employ further suggest RNA editing can moonlight as a splicing-modulator, albeit less frequently than genomic sequence diversity. Beyond existing annotations, we demonstrate that the ultra-high resolution of RNA-Seq combined from 462 individuals also provides evidence for thousands of bona fide novel elements of RNA processing-alternative splice sites, introns, and cleavage sites-which are often rare and lowly expressed but in other characteristics similar to their annotated counterparts.
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Affiliation(s)
- Pedro G. Ferreira
- Bioinformatics and Genomics, Center for Genomic Regulation (CRG), 08003 Barcelona, Catalonia, Spain
- Department of Genetic Medicine and Development, University of Geneva Medical School, 1211 Geneva, Switzerland
- Instituto de Investigação e Inovação em Saúde, (i3S) Universidade do Porto, 4200-625 Porto, Portugal
- Institute of Molecular Pathology and Immunology (IPATIMUP), University of Porto, 4200-625 Porto, Portugal
| | - Martin Oti
- Institute of Biophysics Carlos Chagas Filho (IBCCF), Federal University of Rio de Janeiro (UFRJ), 21941-902 Rio de Janeiro, Brazil
| | - Matthias Barann
- Institute of Clinical Molecular Biology, Christians-Albrechts-Universität zu Kiel, 24105 Kiel, Germany
| | - Thomas Wieland
- Institute of Human Genetics, Helmholtz Center Munich, 85764 Neuherberg, Germany
| | - Suzana Ezquina
- Center for Human Genome and Stem-cell research (HUG-CELL), University of São Paulo (USP), 05508090 São Paulo, Brazil
| | - Marc R. Friedländer
- Science for Life Laboratory, Stockholm University, Box 1031, 17121 Solna, Sweden
| | - Manuel A. Rivas
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, United Kingdom
| | - Anna Esteve-Codina
- Centre Nacional d’Anàlisi Genòmica, 08028 Barcelona, Catalonia, Spain
- Center for Research in Agricultural Genomics (CRAG), Autonome University of Barcelona, 08193 Bellaterra, Catalonia, Spain
| | - Philip Rosenstiel
- Institute of Clinical Molecular Biology, Christians-Albrechts-Universität zu Kiel, 24105 Kiel, Germany
| | - Tim M Strom
- Institute of Human Genetics, Helmholtz Center Munich, 85764 Neuherberg, Germany
- Institute of Human Genetics, Technische Universität München, 81675 Munich, Germany
| | - Tuuli Lappalainen
- Department of Genetic Medicine and Development, University of Geneva Medical School, 1211 Geneva, Switzerland
- Institute for Genetics and Genomics in Geneva (iGE3), University of Geneva, 1211 Geneva, Switzerland
- Swiss Institute of Bioinformatics, 1211 Geneva, Switzerland
| | - Roderic Guigó
- Bioinformatics and Genomics, Center for Genomic Regulation (CRG), 08003 Barcelona, Catalonia, Spain
- Pompeu Fabra University (UPF), 08003 Barcelona, Catalonia, Spain
| | - Michael Sammeth
- Bioinformatics and Genomics, Center for Genomic Regulation (CRG), 08003 Barcelona, Catalonia, Spain
- Institute of Biophysics Carlos Chagas Filho (IBCCF), Federal University of Rio de Janeiro (UFRJ), 21941-902 Rio de Janeiro, Brazil
- National Center of Scientific Computing (LNCC), 2233-6000 Petrópolis, Rio de Janeiro, Brazil
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28
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Geuens T, Bouhy D, Timmerman V. The hnRNP family: insights into their role in health and disease. Hum Genet 2016; 135:851-67. [PMID: 27215579 PMCID: PMC4947485 DOI: 10.1007/s00439-016-1683-5] [Citation(s) in RCA: 655] [Impact Index Per Article: 81.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Accepted: 05/09/2016] [Indexed: 12/14/2022]
Abstract
Heterogeneous nuclear ribonucleoproteins (hnRNPs) represent a large family of RNA-binding proteins (RBPs) that contribute to multiple aspects of nucleic acid metabolism including alternative splicing, mRNA stabilization, and transcriptional and translational regulation. Many hnRNPs share general features, but differ in domain composition and functional properties. This review will discuss the current knowledge about the different hnRNP family members, focusing on their structural and functional divergence. Additionally, we will highlight their involvement in neurodegenerative diseases and cancer, and the potential to develop RNA-based therapies.
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Affiliation(s)
- Thomas Geuens
- Peripheral Neuropathy Group, VIB Molecular Genetics Department, University of Antwerp-CDE, Parking P4, Building V, Room 1.30, Universiteitsplein 1, 2610, Antwerp, Belgium
- Neurogenetics Laboratory, Institute Born Bunge, University of Antwerp, Antwerp, Belgium
| | - Delphine Bouhy
- Peripheral Neuropathy Group, VIB Molecular Genetics Department, University of Antwerp-CDE, Parking P4, Building V, Room 1.30, Universiteitsplein 1, 2610, Antwerp, Belgium
- Neurogenetics Laboratory, Institute Born Bunge, University of Antwerp, Antwerp, Belgium
| | - Vincent Timmerman
- Peripheral Neuropathy Group, VIB Molecular Genetics Department, University of Antwerp-CDE, Parking P4, Building V, Room 1.30, Universiteitsplein 1, 2610, Antwerp, Belgium.
- Neurogenetics Laboratory, Institute Born Bunge, University of Antwerp, Antwerp, Belgium.
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29
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IntSplice: prediction of the splicing consequences of intronic single-nucleotide variations in the human genome. J Hum Genet 2016; 61:633-40. [PMID: 27009626 DOI: 10.1038/jhg.2016.23] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Revised: 02/23/2016] [Accepted: 02/24/2016] [Indexed: 01/20/2023]
Abstract
Precise spatiotemporal regulation of splicing is mediated by splicing cis-elements on pre-mRNA. Single-nucleotide variations (SNVs) affecting intronic cis-elements possibly compromise splicing, but no efficient tool has been available to identify them. Following an effect-size analysis of each intronic nucleotide on annotated alternative splicing, we extracted 105 parameters that could affect the strength of the splicing signals. However, we could not generate reliable support vector regression models to predict the percent-splice-in (PSI) scores for normal human tissues. Next, we generated support vector machine (SVM) models using 110 parameters to directly differentiate pathogenic SNVs in the Human Gene Mutation Database and normal SNVs in the dbSNP database, and we obtained models with a sensitivity of 0.800±0.041 (mean and s.d.) and a specificity of 0.849±0.021. Our IntSplice models were more discriminating than SVM models that we generated with Shapiro-Senapathy score and MaxEntScan::score3ss. We applied IntSplice to a naturally occurring and nine artificial intronic mutations in RAPSN causing congenital myasthenic syndrome. IntSplice correctly predicted the splicing consequences for nine of the ten mutants. We created a web service program, IntSplice (http://www.med.nagoya-u.ac.jp/neurogenetics/IntSplice) to predict splicing-affecting SNVs at intronic positions from -50 to -3.
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30
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Sohail M, Xie J. Diverse regulation of 3' splice site usage. Cell Mol Life Sci 2015; 72:4771-93. [PMID: 26370726 PMCID: PMC11113787 DOI: 10.1007/s00018-015-2037-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2015] [Revised: 08/12/2015] [Accepted: 09/03/2015] [Indexed: 01/13/2023]
Abstract
The regulation of splice site (SS) usage is important for alternative pre-mRNA splicing and thus proper expression of protein isoforms in cells; its disruption causes diseases. In recent years, an increasing number of novel regulatory elements have been found within or nearby the 3'SS in mammalian genes. The diverse elements recruit a repertoire of trans-acting factors or form secondary structures to regulate 3'SS usage, mostly at the early steps of spliceosome assembly. Their mechanisms of action mainly include: (1) competition between the factors for RNA elements, (2) steric hindrance between the factors, (3) direct interaction between the factors, (4) competition between two splice sites, or (5) local RNA secondary structures or longer range loops, according to the mode of protein/RNA interactions. Beyond the 3'SS, chromatin remodeling/transcription, posttranslational modifications of trans-acting factors and upstream signaling provide further layers of regulation. Evolutionarily, some of the 3'SS elements seem to have emerged in mammalian ancestors. Moreover, other possibilities of regulation such as that by non-coding RNA remain to be explored. It is thus likely that there are more diverse elements/factors and mechanisms that influence the choice of an intron end. The diverse regulation likely contributes to a more complex but refined transcriptome and proteome in mammals.
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Affiliation(s)
- Muhammad Sohail
- Department of Physiology and Pathophysiology, College of Medicine, Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, R3E 0J9, Canada
| | - Jiuyong Xie
- Department of Physiology and Pathophysiology, College of Medicine, Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, R3E 0J9, Canada.
- Department of Biochemistry and Medical Genetics, College of Medicine, Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, R3E 0J9, Canada.
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31
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SRSF1 and hnRNP H antagonistically regulate splicing of COLQ exon 16 in a congenital myasthenic syndrome. Sci Rep 2015; 5:13208. [PMID: 26282582 PMCID: PMC4539547 DOI: 10.1038/srep13208] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2015] [Accepted: 07/22/2015] [Indexed: 12/28/2022] Open
Abstract
The catalytic subunits of acetylcholinesterase (AChE) are anchored in the basal lamina of the neuromuscular junction using a collagen-like tail subunit (ColQ) encoded by COLQ. Mutations in COLQ cause endplate AChE deficiency. An A-to-G mutation predicting p.E415G in COLQ exon 16 identified in a patient with endplate AChE deficiency causes exclusive skipping of exon 16. RNA affinity purification, mass spectrometry, and siRNA-mediated gene knocking down disclosed that the mutation disrupts binding of a splicing-enhancing RNA-binding protein, SRSF1, and de novo gains binding of a splicing-suppressing RNA-binding protein, hnRNP H. MS2-mediated artificial tethering of each factor demonstrated that SRSF1 and hnRNP H antagonistically modulate splicing by binding exclusively to the target in exon 16. Further analyses with artificial mutants revealed that SRSF1 is able to bind to degenerative binding motifs, whereas hnRNP H strictly requires an uninterrupted stretch of poly(G). The mutation compromised splicing of the downstream intron. Isolation of early spliceosome complex revealed that the mutation impairs binding of U1-70K (snRNP70) to the downstream 5′ splice site. Global splicing analysis with RNA-seq revealed that exons carrying the hnRNP H-binding GGGGG motif are predisposed to be skipped compared to those carrying the SRSF1-binding GGAGG motif in both human and mouse brains.
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Tei S, Ishii HT, Mitsuhashi H, Ishiura S. Antisense oligonucleotide-mediated exon skipping of CHRNA1 pre-mRNA as potential therapy for Congenital Myasthenic Syndromes. Biochem Biophys Res Commun 2015; 461:481-6. [PMID: 25888793 DOI: 10.1016/j.bbrc.2015.04.035] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2015] [Accepted: 04/06/2015] [Indexed: 10/23/2022]
Abstract
CHRNA1 encodes the α subunit of nicotinic acetylcholine receptors (nAChRs) and is expressed at the neuromuscular junction. Moreover, it is one of the causative genes of Congenital Myasthenic Syndromes (CMS). CHRNA1 undergoes alternative splicing to produce two splice variants: P3A(-), without exon P3A, and P3A(+), with the exon P3A. Only P3A(-) forms functional nAChR. Aberrant alternative splicing caused by intronic or exonic point mutations in patients leads to an extraordinary increase in P3A(+) and a concomitant decrease in P3A(-). Consequently this resulted in a shortage of functional receptors. Aiming to restore the imbalance between the two splice products, antisense oligonucleotides (AONs) were employed to induce exon P3A skipping. Three AON sequences were designed to sterically block the putative binding sequences for splicing factors necessary for exon recognition. Herein, we show that AON complementary to the 5' splice site of the exon was the most effective at exon skipping of the minigene with causative mutations, as well as endogenous wild-type CHRNA1. We conclude that single administration of the AON against the 5' splice site is a promising therapeutic approach for patients based on the dose-dependent effect of the AON and the additive effect of combined AONs. This conclusion is favorable to patients with inherited diseases of uncertain etiology that arise from aberrant splicing leading to a subsequent loss of functional translation products because our findings encourage the option of AON treatment as a therapeutic for these prospectively identified diseases.
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Affiliation(s)
- Shoin Tei
- Department of Life-Science, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo, Japan
| | - Hiroshige T Ishii
- Department of Life-Science, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo, Japan
| | - Hiroaki Mitsuhashi
- Department of Life-Science, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo, Japan
| | - Shoichi Ishiura
- Department of Life-Science, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo, Japan.
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HnRNP C, YB-1 and hnRNP L coordinately enhance skipping of human MUSK exon 10 to generate a Wnt-insensitive MuSK isoform. Sci Rep 2014; 4:6841. [PMID: 25354590 PMCID: PMC4213890 DOI: 10.1038/srep06841] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2014] [Accepted: 10/13/2014] [Indexed: 12/11/2022] Open
Abstract
Muscle specific receptor tyrosine kinase (MuSK) is an essential postsynaptic transmembrane molecule that mediates clustering of acetylcholine receptors (AChR). MUSK exon 10 is alternatively skipped in human, but not in mouse. Skipping of this exon disrupts a cysteine-rich region (Fz-CRD), which is essential for Wnt-mediated AChR clustering. To investigate the underlying mechanisms of alternative splicing, we exploited block-scanning mutagenesis with human minigene and identified a 20-nucleotide block that contained exonic splicing silencers. Using RNA-affinity purification, mass spectrometry, and Western blotting, we identified that hnRNP C, YB-1 and hnRNP L are bound to MUSK exon 10. siRNA-mediated knockdown and cDNA overexpression confirmed the additive, as well as the independent, splicing suppressing effects of hnRNP C, YB-1 and hnRNP L. Antibody-mediated in vitro protein depletion and scanning mutagenesis additionally revealed that binding of hnRNP C to RNA subsequently promotes binding of YB-1 and hnRNP L to the immediate downstream sites and enhances exon skipping. Simultaneous tethering of two splicing trans-factors to the target confirmed the cooperative effect of YB-1 and hnRNP L on hnRNP C-mediated exon skipping. Search for a similar motif in the human genome revealed nine alternative exons that were individually or coordinately regulated by hnRNP C and YB-1.
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Inherited disorders of the neuromuscular junction: an update. J Neurol 2014; 261:2234-43. [PMID: 25305004 DOI: 10.1007/s00415-014-7520-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2014] [Accepted: 09/23/2014] [Indexed: 10/24/2022]
Abstract
Congenital myasthenic syndromes (CMSs) are a group of heterogeneous inherited disorders caused by mutations in genes affecting the function and structure of the neuromuscular junction. This review updates the reader on established and novel subtypes of congenital myasthenia, and the treatment strategies for these increasingly heterogeneous disorders. The discovery of mutations associated with the N-glycosylation pathway and in the family of serine peptidases has shown that causative genes encoding ubiquitously expressed molecules can produce defects at the human neuromuscular junction. By contrast, mutations in lipoprotein-like receptor 4 (LRP4), a long-time candidate gene for congenital myasthenia, and a novel phenotype of myasthenia with distal weakness and atrophy due to mutations in AGRN have now been described. In addition, a pathogenic splicing mutation in a nonfunctional exon of CHRNA1 has been reported emphasizing the importance of analysing nonfunctional exons in genetic analysis. The benefit of salbutamol and ephedrine alone or combined with pyridostigmine or 3,4-DAP is increasingly being reported for particular subtypes of CMS.
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Refinement of the spectra of exon usage by combined effects of extracellular stimulus and intracellular factors. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2014; 1839:537-45. [PMID: 24844182 DOI: 10.1016/j.bbagrm.2014.05.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2014] [Revised: 04/29/2014] [Accepted: 05/12/2014] [Indexed: 11/23/2022]
Abstract
Finely tuned differential expression of alternative splice variants contributes to important physiological processes such as the fine-tuning of electrical firing or hearing frequencies; yet the underlying molecular basis for the expression control is not clear. The inclusion levels of four depolarization-regulated alternative exons were measured by RT-PCR in GH3 pituitary cells under different conditions of stimulation and/or RNA interference of splicing factors. The usage of the exons was reduced by membrane depolarization to various extents and was differentially modulated by the knock-down of splicing factors hnRNP L, L-like, I (PTBP1) or K or their combinations. A spectrum of each exon's level was produced under six knock-down conditions and was significantly shifted by depolarization. When all these conditions were considered together, a more refined or expanded spectrum of exon usage was obtained for each of the four exons. As a proof of principle for the molecular basis of the fine-tuning of exon usage, we show in the cases of hnRNP L and LL that their differential effects through the same element or different combinations of RNA sequences by the same factor hnRNP L are critical. The results thus demonstrate that the combined effect of varying extracellular stimuli and intracellular factors/RNA sequences refines or expands the spectra of endogenous exon usage, likely contributing to the fine-tuning of cellular properties.
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