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Abstract
Examples of associations between human disease and defects in pre-messenger RNA splicing/alternative splicing are accumulating. Although many alterations are caused by mutations in splicing signals or regulatory sequence elements, recent studies have noted the disruptive impact of mutated generic spliceosome components and splicing regulatory proteins. This review highlights recent progress in our understanding of how the altered splicing function of RNA-binding proteins contributes to myelodysplastic syndromes, cancer, and neuropathologies.
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Affiliation(s)
- Benoit Chabot
- Centre of Excellence in RNA Biology, Department of Microbiology and Infectious Diseases, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Québec J1E 4K8, Canada
| | - Lulzim Shkreta
- Centre of Excellence in RNA Biology, Department of Microbiology and Infectious Diseases, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Québec J1E 4K8, Canada
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152
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Liver-Specific Deletion of SRSF2 Caused Acute Liver Failure and Early Death in Mice. Mol Cell Biol 2016; 36:1628-38. [PMID: 27022105 DOI: 10.1128/mcb.01071-15] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Accepted: 03/21/2016] [Indexed: 12/21/2022] Open
Abstract
The liver performs a variety of unique functions critical for metabolic homeostasis. Here, we show that mice lacking the splicing factor SRSF2 but not SRSF1 in hepatocytes have severe liver pathology and biochemical abnormalities. Histological analyses revealed generalized hepatitis with the presence of ballooned hepatocytes and evidence of fibrosis. Molecular analysis demonstrated that SRSF2 governs splicing of multiple genes involved in the stress-induced cell death pathway in the liver. More importantly, SRSF2 also functions as a potent transcription activator, required for efficient expression of transcription factors mainly responsible for energy homeostasis and bile acid metabolism in the liver. Consistent with the effects of SRSF2 in gene regulation, accumulation of total cholesterol and bile acids was prominently observed in the mutant liver, followed by enhanced generation of reactive oxygen species and increased endoplasmic reticulum stress, as revealed by biochemical and ultrastructural analyses. Taking these observations together, inactivation of SRSF2 in liver caused dysregulated splicing events and hepatic metabolic disorders, which trigger endoplasmic reticulum stress, oxidative stress, and finally liver failure.
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153
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Modulation of splicing catalysis for therapeutic targeting of leukemia with mutations in genes encoding spliceosomal proteins. Nat Med 2016; 22:672-8. [PMID: 27135740 PMCID: PMC4899191 DOI: 10.1038/nm.4097] [Citation(s) in RCA: 265] [Impact Index Per Article: 33.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2016] [Accepted: 04/06/2016] [Indexed: 12/15/2022]
Abstract
Mutations in spliceosomal genes are commonly found in patients with myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML)1–3. These mutations occur at highly recurrent amino acid residues and perturb normal splice site and exon recognition4–6. Spliceosomal mutations are always heterozygous and rarely co-occur with one another, suggesting that cells may only tolerate a partial deviation from normal splicing activity. To test this hypothesis, we engineered mice that express the SRSF2P95H mutation, which commonly occurs in MDS and AML, in an inducible hemizygous manner in hematopoietic cells. These mice developed lethal bone marrow failure, demonstrating that Srsf2-mutant cells depend on the wildtype Srsf2 allele for survival. In the context of leukemia, treatment with the spliceosome inhibitor E71077,8 resulted in significant reductions in leukemic burden specifically in isogenic mouse leukemias and patient-derived xenograft (PDX) AMLs carrying spliceosomal mutations. While in vivo E7107 exposure resulted in widespread intron retention and cassette exon skipping regardless of Srsf2 genotype, the magnitude of splicing inhibition following E7107 treatment was greater in Srsf2-mutant versus wildtype leukemias, consistent with its differential effect on survival in these two genotypes. Collectively, these data provide genetic and pharmacologic evidence that leukemias with spliceosomal mutations are preferentially susceptible to additional splicing perturbations in vivo compared with wildtype counterparts. Modulation of spliceosome function may provide a novel therapeutic avenue in genetically defined subsets of MDS and AML patients.
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154
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Inoue D, Bradley RK, Abdel-Wahab O. Spliceosomal gene mutations in myelodysplasia: molecular links to clonal abnormalities of hematopoiesis. Genes Dev 2016; 30:989-1001. [PMID: 27151974 PMCID: PMC4863743 DOI: 10.1101/gad.278424.116] [Citation(s) in RCA: 85] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Genomic analyses of the myeloid malignancies and clonal disorders of hematopoiesis that may give rise to these disorders have identified that mutations in genes encoding core spliceosomal proteins and accessory regulatory splicing factors are among the most common targets of somatic mutations. These spliceosomal mutations often occur in a mutually exclusive manner with one another and, in aggregate, account for the most frequent class of mutations in patients with myelodysplastic syndromes (MDSs) in particular. Although substantial progress has been made in understanding the effects of several of these mutations on splicing and splice site recognition, functional connections linking the mechanistic changes in splicing induced by these mutations to the phenotypic consequences of clonal and aberrant hematopoiesis are not yet well defined. This review describes our current understanding of the mechanistic and biological effects of spliceosomal gene mutations in MDSs as well as the regulation of splicing throughout normal hematopoiesis.
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Affiliation(s)
- Daichi Inoue
- Human Oncology and Pathogenesis Program, Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA
| | - Robert K Bradley
- Computational Biology Program, Public Health Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA; Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA
| | - Omar Abdel-Wahab
- Human Oncology and Pathogenesis Program, Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA; Leukemia Service, Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA
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155
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Järvelin AI, Noerenberg M, Davis I, Castello A. The new (dis)order in RNA regulation. Cell Commun Signal 2016; 14:9. [PMID: 27048167 PMCID: PMC4822317 DOI: 10.1186/s12964-016-0132-3] [Citation(s) in RCA: 154] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Accepted: 03/21/2016] [Indexed: 02/03/2023] Open
Abstract
RNA-binding proteins play a key role in the regulation of all aspects of RNA metabolism, from the synthesis of RNA to its decay. Protein-RNA interactions have been thought to be mostly mediated by canonical RNA-binding domains that form stable secondary and tertiary structures. However, a number of pioneering studies over the past decades, together with recent proteome-wide data, have challenged this view, revealing surprising roles for intrinsically disordered protein regions in RNA binding. Here, we discuss how disordered protein regions can mediate protein-RNA interactions, conceptually grouping these regions into RS-rich, RG-rich, and other basic sequences, that can mediate both specific and non-specific interactions with RNA. Disordered regions can also influence RNA metabolism through protein aggregation and hydrogel formation. Importantly, protein-RNA interactions mediated by disordered regions can influence nearly all aspects of co- and post-transcriptional RNA processes and, consequently, their disruption can cause disease. Despite growing interest in disordered protein regions and their roles in RNA biology, their mechanisms of binding, regulation, and physiological consequences remain poorly understood. In the coming years, the study of these unorthodox interactions will yield important insights into RNA regulation in cellular homeostasis and disease.
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Affiliation(s)
- Aino I. Järvelin
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU UK
| | - Marko Noerenberg
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU UK
| | - Ilan Davis
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU UK
| | - Alfredo Castello
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU UK
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156
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Abstract
RNA splicing represents a post-transcriptional mechanism to generate multiple functional RNAs or proteins from a single transcript. The evolution of RNA splicing is a prime example of the Darwinian function follows form concept. A mutation that leads to a new mRNA (form) that encodes for a new functional protein (function) is likely to be retained, and this way, the genome has gradually evolved to encode for genes with multiple isoforms, thereby creating an enormously diverse transcriptome. Advances in technologies to characterize RNA populations have led to a better understanding of RNA processing in health and disease. In the heart, alternative splicing is increasingly being recognized as an important layer of post-transcriptional gene regulation. Moreover, the recent identification of several cardiac splice factors, such as RNA-binding motif protein 20 and SF3B1, not only provided important insight into the mechanisms underlying alternative splicing but also revealed how these splicing factors impact functional properties of the heart. Here, we review our current knowledge of alternative splicing in the heart, with a particular focus on the major and minor spliceosome, the factors controlling RNA splicing, and the role of alternative splicing in cardiac development and disease.
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Affiliation(s)
- Maarten M.G. van den Hoogenhof
- From the Department of Experimental Cardiology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Yigal M. Pinto
- From the Department of Experimental Cardiology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Esther E. Creemers
- From the Department of Experimental Cardiology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
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157
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Abstract
The human transcriptome is composed of a vast RNA population that undergoes further diversification by splicing. Detecting specific splice sites in this large sequence pool is the responsibility of the major and minor spliceosomes in collaboration with numerous splicing factors. This complexity makes splicing susceptible to sequence polymorphisms and deleterious mutations. Indeed, RNA mis-splicing underlies a growing number of human diseases with substantial societal consequences. Here, we provide an overview of RNA splicing mechanisms followed by a discussion of disease-associated errors, with an emphasis on recently described mutations that have provided new insights into splicing regulation. We also discuss emerging strategies for splicing-modulating therapy.
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Affiliation(s)
- Marina M Scotti
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics and the Genetics Institute, University of Florida, College of Medicine, Gainesville, Florida 32610-3610 USA
| | - Maurice S Swanson
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics and the Genetics Institute, University of Florida, College of Medicine, Gainesville, Florida 32610-3610 USA
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158
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Daguenet E, Dujardin G, Valcárcel J. The pathogenicity of splicing defects: mechanistic insights into pre-mRNA processing inform novel therapeutic approaches. EMBO Rep 2015; 16:1640-55. [PMID: 26566663 DOI: 10.15252/embr.201541116] [Citation(s) in RCA: 102] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Accepted: 10/12/2015] [Indexed: 12/22/2022] Open
Abstract
Removal of introns from pre-mRNA precursors (pre-mRNA splicing) is a necessary step for the expression of most genes in multicellular organisms, and alternative patterns of intron removal diversify and regulate the output of genomic information. Mutation or natural variation in pre-mRNA sequences, as well as in spliceosomal components and regulatory factors, has been implicated in the etiology and progression of numerous pathologies. These range from monogenic to multifactorial genetic diseases, including metabolic syndromes, muscular dystrophies, neurodegenerative and cardiovascular diseases, and cancer. Understanding the molecular mechanisms associated with splicing-related pathologies can provide key insights into the normal function and physiological context of the complex splicing machinery and establish sound basis for novel therapeutic approaches.
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Affiliation(s)
- Elisabeth Daguenet
- Centre de Regulació Genòmica (CRG), The Barcelona Institute of Science and Technology, Barcelona, Spain Universitat Pompeu-Fabra, Barcelona, Spain
| | - Gwendal Dujardin
- Centre de Regulació Genòmica (CRG), The Barcelona Institute of Science and Technology, Barcelona, Spain Universitat Pompeu-Fabra, Barcelona, Spain
| | - Juan Valcárcel
- Centre de Regulació Genòmica (CRG), The Barcelona Institute of Science and Technology, Barcelona, Spain Universitat Pompeu-Fabra, Barcelona, Spain Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain
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