1
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Cotto KC, Feng YY, Ramu A, Richters M, Freshour SL, Skidmore ZL, Xia H, McMichael JF, Kunisaki J, Campbell KM, Chen THP, Rozycki EB, Adkins D, Devarakonda S, Sankararaman S, Lin Y, Chapman WC, Maher CA, Arora V, Dunn GP, Uppaluri R, Govindan R, Griffith OL, Griffith M. Integrated analysis of genomic and transcriptomic data for the discovery of splice-associated variants in cancer. Nat Commun 2023; 14:1589. [PMID: 36949070 PMCID: PMC10033906 DOI: 10.1038/s41467-023-37266-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Accepted: 03/08/2023] [Indexed: 03/24/2023] Open
Abstract
Somatic mutations within non-coding regions and even exons may have unidentified regulatory consequences that are often overlooked in analysis workflows. Here we present RegTools ( www.regtools.org ), a computationally efficient, free, and open-source software package designed to integrate somatic variants from genomic data with splice junctions from bulk or single cell transcriptomic data to identify variants that may cause aberrant splicing. We apply RegTools to over 9000 tumor samples with both tumor DNA and RNA sequence data. RegTools discovers 235,778 events where a splice-associated variant significantly increases the splicing of a particular junction, across 158,200 unique variants and 131,212 unique junctions. To characterize these somatic variants and their associated splice isoforms, we annotate them with the Variant Effect Predictor, SpliceAI, and Genotype-Tissue Expression junction counts and compare our results to other tools that integrate genomic and transcriptomic data. While many events are corroborated by the aforementioned tools, the flexibility of RegTools also allows us to identify splice-associated variants in known cancer drivers, such as TP53, CDKN2A, and B2M, and other genes.
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Affiliation(s)
- Kelsy C Cotto
- Division of Oncology, Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA
- McDonnell Genome Institute, Washington University School of Medicine, St. Louis, MO, USA
| | - Yang-Yang Feng
- McDonnell Genome Institute, Washington University School of Medicine, St. Louis, MO, USA
| | - Avinash Ramu
- Department of Genetics, Washington University School of Medicine, St. Louis, MO, USA
| | - Megan Richters
- Division of Oncology, Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA
- McDonnell Genome Institute, Washington University School of Medicine, St. Louis, MO, USA
| | - Sharon L Freshour
- Division of Oncology, Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA
- McDonnell Genome Institute, Washington University School of Medicine, St. Louis, MO, USA
| | - Zachary L Skidmore
- Division of Oncology, Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA
- McDonnell Genome Institute, Washington University School of Medicine, St. Louis, MO, USA
| | - Huiming Xia
- Division of Oncology, Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA
- McDonnell Genome Institute, Washington University School of Medicine, St. Louis, MO, USA
| | - Joshua F McMichael
- McDonnell Genome Institute, Washington University School of Medicine, St. Louis, MO, USA
| | - Jason Kunisaki
- McDonnell Genome Institute, Washington University School of Medicine, St. Louis, MO, USA
| | - Katie M Campbell
- Division of Oncology, Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - Timothy Hung-Po Chen
- Division of Oncology, Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - Emily B Rozycki
- Division of Oncology, Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - Douglas Adkins
- Division of Oncology, Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - Siddhartha Devarakonda
- Division of Oncology, Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - Sumithra Sankararaman
- Division of Oncology, Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - Yiing Lin
- Department of Surgery, Washington University School of Medicine, St. Louis, MO, USA
| | - William C Chapman
- Department of Surgery, Washington University School of Medicine, St. Louis, MO, USA
| | - Christopher A Maher
- Division of Oncology, Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - Vivek Arora
- Division of Oncology, Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - Gavin P Dunn
- Department of Neurosurgery, Mass General Hospital, Boston, MA, USA
- Center for Brain Tumor Immunology and Immunotherapy, Mass General Hospital, Boston, MA, USA
| | - Ravindra Uppaluri
- Department of Surgery, Brigham and Women's Hospital, Boston, MA, USA
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA, USA
| | - Ramaswamy Govindan
- Division of Oncology, Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA
- Siteman Cancer Center, Washington University School of Medicine, St. Louis, MO, USA
| | - Obi L Griffith
- Division of Oncology, Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA.
- McDonnell Genome Institute, Washington University School of Medicine, St. Louis, MO, USA.
- Department of Genetics, Washington University School of Medicine, St. Louis, MO, USA.
- Siteman Cancer Center, Washington University School of Medicine, St. Louis, MO, USA.
| | - Malachi Griffith
- Division of Oncology, Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA.
- McDonnell Genome Institute, Washington University School of Medicine, St. Louis, MO, USA.
- Department of Genetics, Washington University School of Medicine, St. Louis, MO, USA.
- Siteman Cancer Center, Washington University School of Medicine, St. Louis, MO, USA.
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2
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Cooperative Binding of SRSF3 to Structured 3'ss-α Exon RNA during α Exon Inclusion in the ZO-1 mRNA. Curr Issues Mol Biol 2023; 45:593-603. [PMID: 36661525 PMCID: PMC9857539 DOI: 10.3390/cimb45010039] [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: 12/07/2022] [Revised: 12/28/2022] [Accepted: 01/03/2023] [Indexed: 01/11/2023] Open
Abstract
ZO-1α+ and ZO-1α- proteins are expressed in hermetic and leaky tight junctions, respectively. Two cis-acting distant exonic elements partly activate the 240 nucleotide-long α exon producing the ZO-1α+ isoform. However, the elements within and around the α exon and their respective factors involved in its splicing are unknown. To study the dynamic interaction between SRSF3 and its bioinformatically predicted target sites around the 3'ss upstream of the α exon during its activation, we performed EMSA, crosslinking, and in vivo splicing assays by ZO-1 minigene expression and siRNA-mediated silencing in transfected cells. Using V1 RNase, we probed the possible formation of a hairpin RNA structure between the intronic and proximal exonic SRSF3 binding sites. The hairpin sufficed for complex formations in the EMSA. The interaction of SRSF3 with the intronic site promoted the cooperative binding of SRSF3 to the exonic site. Finally, SRSF3 restored α exon activation in SRSF3 knockdown transfectants. Altogether, our results show that SRSF3-hairpin RNA interaction is crucial in the early recognition of 3'ss for α exon activation. It remains to be explored whether SRSF3 recruits or stabilizes the binding of other factors or brings separate splice sites into proximity.
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3
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Sarkar A, Panati K, Narala VR. Code inside the codon: The role of synonymous mutations in regulating splicing machinery and its impact on disease. MUTATION RESEARCH. REVIEWS IN MUTATION RESEARCH 2022; 790:108444. [PMID: 36307006 DOI: 10.1016/j.mrrev.2022.108444] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Revised: 10/10/2022] [Accepted: 10/21/2022] [Indexed: 11/06/2022]
Abstract
In eukaryotes, precise pre-mRNA processing, including alternative splicing, is essential to carry out the intricate protein translation process. Both point mutations (that alter the translated protein sequence) and synonymous mutations (that do not alter the translated protein sequence) are capable of affecting the splicing process. Synonymous mutations are known to affect gene expression via altering mRNA stability, mRNA secondary structure, splicing processes, and translational kinetics. In higher eukaryotes, precise splicing is regulated by three weakly conserved cis-elements, 5' and 3' splice sites and the branch site. Many other cis-acting elements (exonic/intronic splicing enhancers and silencers) and trans-acting splicing factors (serine and arginine-rich proteins and heterogeneous nuclear ribonucleoproteins) have also been found to enhance or suppress the splicing process. The appearance of synonymous mutations in cis-acting elements can alter the splicing process by changing the binding pattern of splicing factors to exonic splicing enhancers or silencer motifs. This results in exon skipping, intron retention, and various other forms of alternative splicing, eventually leading to the emergence of a wide range of diseases. The focus of this review is to elucidate the role of synonymous mutations and their impact on abnormal splicing mechanisms. Further, this study highlights the function of synonymous mutation in mediating abnormal splicing in cancer and development of X-linked, and autosomal inherited diseases.
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Affiliation(s)
- Avik Sarkar
- Department of Zoology, Vidyasagar University, Midnapore, West Bengal 721102, India
| | - Kalpana Panati
- Department of Biotechnology, Government College for Men, Kadapa 516004, India
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4
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Stanley RF, Abdel-Wahab O. Dysregulation and therapeutic targeting of RNA splicing in cancer. NATURE CANCER 2022; 3:536-546. [PMID: 35624337 PMCID: PMC9551392 DOI: 10.1038/s43018-022-00384-z] [Citation(s) in RCA: 54] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Accepted: 04/22/2022] [Indexed: 05/15/2023]
Abstract
High-throughput sequencing and functional characterization of the cancer transcriptome have uncovered cancer-specific dysregulation of RNA splicing across a variety of cancers. Alterations in the cancer genome and dysregulation of RNA splicing factors lead to missplicing, splicing alteration-dependent gene expression and, in some cases, generation of novel splicing-derived proteins. Here, we review recent advances in our understanding of aberrant splicing in cancer pathogenesis and present strategies to harness cancer-specific aberrant splicing for therapeutic intent.
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Affiliation(s)
- Robert F Stanley
- Human Oncology and Pathogenesis Program and Leukemia Service, Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Omar Abdel-Wahab
- Human Oncology and Pathogenesis Program and Leukemia Service, Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY, USA.
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5
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Yu Z, Zhu J, Wang H, Li H, Jin X. Function of BCLAF1 in human disease. Oncol Lett 2022; 23:58. [PMID: 34992690 PMCID: PMC8721854 DOI: 10.3892/ol.2021.13176] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Accepted: 09/22/2021] [Indexed: 02/06/2023] Open
Abstract
Originally identified as a regulator of apoptosis and transcription, B-cell lymphoma-2-associated transcription factor 1 (BCLAF1) has since been shown to be associated with a multitude of biological processes, such as DNA damage response, splicing and processing of pre-mRNA, T-cell activation, lung development, muscle cell proliferation and differentiation, autophagy, ischemia-reperfusion injury, and viral infection. In recent years, an increasing amount of evidence has shown that BCLAF1 acts as either a tumor promoter or tumor suppressor in tumorigenesis depending on the cellular context and the type of cancer. Even in the same tumor type, BCLAF1 may have opposite effects. In the present review, the subcellular localization, structural features, mutations within BCLAF1 will be described, then the regulation of BCLAF1 and its downstream targets will be analyzed. Furthermore, the different roles and possible mechanisms of BCLAF1 in tumorigenesis will also be highlighted and discussed. Finally, BCLAF1 may be considered as a potential target for cancer therapy in the future.
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Affiliation(s)
- Zongdong Yu
- Department of Hepatobiliary and Pancreatic Surgery, Ningbo Medical Center of LiHuiLi Hospital, Ningbo University, Ningbo, Zhejiang 315040, P.R. China.,Department of Biochemistry and Molecular Biology, Zhejiang Key Laboratory of Pathophysiology, Medical School of Ningbo University, Ningbo, Zhejiang 315211, P.R. China
| | - Jie Zhu
- Department of Hepatobiliary and Pancreatic Surgery, Ningbo Medical Center of LiHuiLi Hospital, Ningbo University, Ningbo, Zhejiang 315040, P.R. China.,Department of Biochemistry and Molecular Biology, Zhejiang Key Laboratory of Pathophysiology, Medical School of Ningbo University, Ningbo, Zhejiang 315211, P.R. China
| | - Haibiao Wang
- Department of Biochemistry and Molecular Biology, Zhejiang Key Laboratory of Pathophysiology, Medical School of Ningbo University, Ningbo, Zhejiang 315211, P.R. China
| | - Hong Li
- Department of Hepatobiliary and Pancreatic Surgery, Ningbo Medical Center of LiHuiLi Hospital, Ningbo University, Ningbo, Zhejiang 315040, P.R. China.,Department of Biochemistry and Molecular Biology, Zhejiang Key Laboratory of Pathophysiology, Medical School of Ningbo University, Ningbo, Zhejiang 315211, P.R. China
| | - Xiaofeng Jin
- Department of Hepatobiliary and Pancreatic Surgery, Ningbo Medical Center of LiHuiLi Hospital, Ningbo University, Ningbo, Zhejiang 315040, P.R. China.,Department of Biochemistry and Molecular Biology, Zhejiang Key Laboratory of Pathophysiology, Medical School of Ningbo University, Ningbo, Zhejiang 315211, P.R. China
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6
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Jobbins AM, Campagne S, Weinmeister R, Lucas CM, Gosliga AR, Clery A, Chen L, Eperon LP, Hodson MJ, Hudson AJ, Allain FHT, Eperon IC. Exon-independent recruitment of SRSF1 is mediated by U1 snRNP stem-loop 3. EMBO J 2022; 41:e107640. [PMID: 34779515 PMCID: PMC8724738 DOI: 10.15252/embj.2021107640] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Revised: 10/04/2021] [Accepted: 10/07/2021] [Indexed: 12/11/2022] Open
Abstract
SRSF1 protein and U1 snRNPs are closely connected splicing factors. They both stimulate exon inclusion, SRSF1 by binding to exonic splicing enhancer sequences (ESEs) and U1 snRNPs by binding to the downstream 5' splice site (SS), and both factors affect 5' SS selection. The binding of U1 snRNPs initiates spliceosome assembly, but SR proteins such as SRSF1 can in some cases substitute for it. The mechanistic basis of this relationship is poorly understood. We show here by single-molecule methods that a single molecule of SRSF1 can be recruited by a U1 snRNP. This reaction is independent of exon sequences and separate from the U1-independent process of binding to an ESE. Structural analysis and cross-linking data show that SRSF1 contacts U1 snRNA stem-loop 3, which is required for splicing. We suggest that the recruitment of SRSF1 to a U1 snRNP at a 5'SS is the basis for exon definition by U1 snRNP and might be one of the principal functions of U1 snRNPs in the core reactions of splicing in mammals.
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Affiliation(s)
- Andrew M Jobbins
- Leicester Institute of Structural & Chemical Biology and Department of Molecular & Cell BiologyUniversity of LeicesterLeicesterUK
- Present address:
MRC London Institute of Medical SciencesLondonUK
- Present address:
Institute of Clinical SciencesImperial College LondonLondonUK
| | - Sébastien Campagne
- Institute of BiochemistryETH ZürichSwitzerland
- Present address:
Inserm U1212CNRS UMR5320ARNA LaboratoryBordeaux CedexFrance
| | - Robert Weinmeister
- Leicester Institute of Structural & Chemical Biology and Department of Molecular & Cell BiologyUniversity of LeicesterLeicesterUK
- Leicester Institute of Structural & Chemical Biology and Department of ChemistryUniversity of LeicesterLeicesterUK
| | - Christian M Lucas
- Leicester Institute of Structural & Chemical Biology and Department of Molecular & Cell BiologyUniversity of LeicesterLeicesterUK
| | - Alison R Gosliga
- Leicester Institute of Structural & Chemical Biology and Department of Molecular & Cell BiologyUniversity of LeicesterLeicesterUK
- Present address:
Institut für Industrielle GenetikAbt.(eilung) SystembiologieUniversität StuttgartStuttgartGermany
| | | | - Li Chen
- Leicester Institute of Structural & Chemical Biology and Department of Molecular & Cell BiologyUniversity of LeicesterLeicesterUK
| | - Lucy P Eperon
- Leicester Institute of Structural & Chemical Biology and Department of Molecular & Cell BiologyUniversity of LeicesterLeicesterUK
| | - Mark J Hodson
- Leicester Institute of Structural & Chemical Biology and Department of Molecular & Cell BiologyUniversity of LeicesterLeicesterUK
| | - Andrew J Hudson
- Leicester Institute of Structural & Chemical Biology and Department of ChemistryUniversity of LeicesterLeicesterUK
| | | | - Ian C Eperon
- Leicester Institute of Structural & Chemical Biology and Department of Molecular & Cell BiologyUniversity of LeicesterLeicesterUK
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7
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Abstract
PURPOSE OF REVIEW Splicing mutations are among the most recurrent genetic perturbations in hematological malignancies, highlighting an important impact of splicing regulation in hematopoietic development. However, compared to our understanding of splicing factor mutations in hematological malignancies, studies of splicing components and alternative splicing in normal hematopoiesis have been less well investigated. Here, we outline the most recent findings on splicing regulation in normal hematopoiesis and discuss the important questions in the field. RECENT FINDINGS Recent studies have highlighted the critical role of splicing regulation in hematopoiesis, including characterization of splicing components in normal hematopoiesis, investigation of transcriptional alterations on splicing, and identification of stage-specific alternative splicing events during hematopoietic development. SUMMARY These interesting findings provide insights on hematopoietic regulation at a co-transcriptional level. More high-throughput RNA ribonucleic acid (RNA) sequencing and functional genomic screens are needed to advance our knowledge of critical alternative splicing patterns in shaping hematopoiesis.
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Affiliation(s)
- Sisi Chen
- Human Oncology and Pathogenesis Program, Dept. of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY, 10065
| | - Omar Abdel-Wahab
- Human Oncology and Pathogenesis Program, Dept. of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY, 10065
- Leukemia Service, Dept. of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY, 10065
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8
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Splicing factor mutations in hematologic malignancies. Blood 2021; 138:599-612. [PMID: 34157091 DOI: 10.1182/blood.2019004260] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Accepted: 10/02/2020] [Indexed: 12/15/2022] Open
Abstract
Mutations in genes encoding RNA splicing factors were discovered nearly ten years ago and are now understood to be amongst the most recurrent genetic abnormalities in patients with all forms of myeloid neoplasms and several types of lymphoproliferative disorders as well as subjects with clonal hematopoiesis. These discoveries implicate aberrant RNA splicing, the process by which precursor RNA is converted into mature messenger RNA, in the development of clonal hematopoietic conditions. Both the protein as well as the RNA components of the splicing machinery are affected by mutations at highly specific residues and a number of these mutations alter splicing in a manner distinct from loss of function. Importantly, cells bearing these mutations have now been shown to generate mRNA species with novel aberrant sequences, some of which may be critical to disease pathogenesis and/or novel targets for therapy. These findings have opened new avenues of research to understand biological pathways disrupted by altered splicing. In parallel, multiple studies have revealed that cells bearing change-of-function mutation in splicing factors are preferentially sensitized to any further genetic or chemical perturbations of the splicing machinery. These discoveries are now being pursued in several early phase clinical trials using molecules with diverse mechanisms of action. Here we review the molecular effects of splicing factor mutations on splicing, mechanisms by which these mutations drive clonal transformation of hematopoietic cells, and the development of new therapeutics targeting these genetic subsets of hematopoietic malignancies.
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9
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El Marabti E, Abdel-Wahab O. Therapeutic Modulation of RNA Splicing in Malignant and Non-Malignant Disease. Trends Mol Med 2021; 27:643-659. [PMID: 33994320 DOI: 10.1016/j.molmed.2021.04.005] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Revised: 04/11/2021] [Accepted: 04/13/2021] [Indexed: 01/24/2023]
Abstract
RNA splicing is the enzymatic process by which non-protein coding sequences are removed from RNA to produce mature protein-coding mRNA. Splicing is thereby a major mediator of proteome diversity as well as a dynamic regulator of gene expression. Genetic alterations disrupting splicing of individual genes or altering the function of splicing factors contribute to a wide range of human genetic diseases as well as cancer. These observations have resulted in the development of therapies based on oligonucleotides that bind to RNA sequences and modulate splicing for therapeutic benefit. In parallel, small molecules that bind to splicing factors to alter their function or modify RNA processing of individual transcripts are being pursued for monogenic disorders as well as for cancer.
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Affiliation(s)
- Ettaib El Marabti
- Clinical Transplant Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Omar Abdel-Wahab
- Human Oncology and Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA; Leukemia Service, Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA.
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10
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Baeza-Centurion P, Miñana B, Valcárcel J, Lehner B. Mutations primarily alter the inclusion of alternatively spliced exons. eLife 2020; 9:59959. [PMID: 33112234 PMCID: PMC7673789 DOI: 10.7554/elife.59959] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Accepted: 10/27/2020] [Indexed: 12/17/2022] Open
Abstract
Genetic analyses and systematic mutagenesis have revealed that synonymous, non-synonymous and intronic mutations frequently alter the inclusion levels of alternatively spliced exons, consistent with the concept that altered splicing might be a common mechanism by which mutations cause disease. However, most exons expressed in any cell are highly-included in mature mRNAs. Here, by performing deep mutagenesis of highly-included exons and by analysing the association between genome sequence variation and exon inclusion across the transcriptome, we report that mutations only very rarely alter the inclusion of highly-included exons. This is true for both exonic and intronic mutations as well as for perturbations in trans. Therefore, mutations that affect splicing are not evenly distributed across primary transcripts but are focussed in and around alternatively spliced exons with intermediate inclusion levels. These results provide a resource for prioritising synonymous and other variants as disease-causing mutations.
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Affiliation(s)
- Pablo Baeza-Centurion
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology (BIST), Barcelona, Spain
| | - Belén Miñana
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology (BIST), Barcelona, Spain
| | - Juan Valcárcel
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology (BIST), Barcelona, Spain.,Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain
| | - Ben Lehner
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology (BIST), Barcelona, Spain.,Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain.,Universitat Pompeu Fabra (UPF), Barcelona, Spain
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11
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Prieto C, Kharas MG. RNA Regulators in Leukemia and Lymphoma. Cold Spring Harb Perspect Med 2020; 10:cshperspect.a034967. [PMID: 31615866 DOI: 10.1101/cshperspect.a034967] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Posttranscriptional regulation of mRNA is a powerful and tightly controlled process in which cells command the integrity, diversity, and abundance of their protein products. RNA-binding proteins (RBPs) are the principal players that control many intermediary steps of posttranscriptional regulation. Recent advances in this field have discovered the importance of RBPs in hematological diseases. Herein we will review a number of RBPs that have been determined to play critical functions in leukemia and lymphoma. Furthermore, we will discuss the potential therapeutic strategies that are currently being studied to specifically target RBPs in these diseases.
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Affiliation(s)
- Camila Prieto
- Molecular Pharmacology Program, Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA
| | - Michael G Kharas
- Molecular Pharmacology Program, Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA
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12
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Aznarez I, Nomakuchi TT, Tetenbaum-Novatt J, Rahman MA, Fregoso O, Rees H, Krainer AR. Mechanism of Nonsense-Mediated mRNA Decay Stimulation by Splicing Factor SRSF1. Cell Rep 2019; 23:2186-2198. [PMID: 29768215 PMCID: PMC5999336 DOI: 10.1016/j.celrep.2018.04.039] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2017] [Revised: 02/20/2018] [Accepted: 04/06/2018] [Indexed: 11/25/2022] Open
Abstract
The splicing factor SRSF1 promotes nonsense-mediated mRNA decay (NMD), a quality control mechanism that degrades mRNAs with premature termination codons (PTCs). Here we show that transcript-bound SRSF1 increases the binding of NMD factor UPF1 to mRNAs while in, or associated with, the nucleus, bypassing UPF2 recruitment and promoting NMD. SRSF1 promotes NMD when positioned downstream of a PTC, which resembles the mode of action of exon junction complex (EJC) and NMD factors. Moreover, splicing and/or EJC deposition increase the effect of SRSF1 on NMD. Lastly, SRSF1 enhances NMD of PTC-containing endogenous transcripts that result from various events. Our findings reveal an alternative mechanism for UPF1 recruitment, uncovering an additional connection between splicing and NMD. SRSF1’s role in the mRNA’s journey from splicing to decay has broad implications for gene expression regulation and genetic diseases.
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Affiliation(s)
- Isabel Aznarez
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA
| | | | | | | | - Oliver Fregoso
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA
| | - Holly Rees
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA
| | - Adrian R Krainer
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA.
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13
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Souček P, Réblová K, Kramárek M, Radová L, Grymová T, Hujová P, Kováčová T, Lexa M, Grodecká L, Freiberger T. High-throughput analysis revealed mutations' diverging effects on SMN1 exon 7 splicing. RNA Biol 2019; 16:1364-1376. [PMID: 31213135 DOI: 10.1080/15476286.2019.1630796] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Splicing-affecting mutations can disrupt gene function by altering the transcript assembly. To ascertain splicing dysregulation principles, we modified a minigene assay for the parallel high-throughput evaluation of different mutations by next-generation sequencing. In our model system, all exonic and six intronic positions of the SMN1 gene's exon 7 were mutated to all possible nucleotide variants, which amounted to 180 unique single-nucleotide mutants and 470 double mutants. The mutations resulted in a wide range of splicing aberrations. Exonic splicing-affecting mutations resulted either in substantial exon skipping, supposedly driven by predicted exonic splicing silencer or cryptic donor splice site (5'ss) and de novo 5'ss strengthening and use. On the other hand, a single disruption of exonic splicing enhancer was not sufficient to cause major exon skipping, suggesting these elements can be substituted during exon recognition. While disrupting the acceptor splice site led only to exon skipping, some 5'ss mutations potentiated the use of three different cryptic 5'ss. Generally, single mutations supporting cryptic 5'ss use displayed better pre-mRNA/U1 snRNA duplex stability and increased splicing regulatory element strength across the original 5'ss. Analyzing double mutants supported the predominating splicing regulatory elements' effect, but U1 snRNA binding could contribute to the global balance of splicing isoforms. Based on these findings, we suggest that creating a new splicing enhancer across the mutated 5'ss can be one of the main factors driving cryptic 5'ss use.
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Affiliation(s)
- Přemysl Souček
- Medical Genomics RG, Central European Institute of Technology, Masaryk University , Brno , Czech Republic.,Molecular Genetics Laboratory, Centre for Cardiovascular Surgery and Transplantation , Brno , Czech Republic
| | - Kamila Réblová
- Medical Genomics RG, Central European Institute of Technology, Masaryk University , Brno , Czech Republic
| | - Michal Kramárek
- Molecular Genetics Laboratory, Centre for Cardiovascular Surgery and Transplantation , Brno , Czech Republic
| | - Lenka Radová
- Medical Genomics RG, Central European Institute of Technology, Masaryk University , Brno , Czech Republic
| | - Tereza Grymová
- Molecular Genetics Laboratory, Centre for Cardiovascular Surgery and Transplantation , Brno , Czech Republic
| | - Pavla Hujová
- Molecular Genetics Laboratory, Centre for Cardiovascular Surgery and Transplantation , Brno , Czech Republic
| | - Tatiana Kováčová
- Medical Genomics RG, Central European Institute of Technology, Masaryk University , Brno , Czech Republic
| | - Matej Lexa
- Faculty of Informatics, Masaryk University , Brno , Czech Republic
| | - Lucie Grodecká
- Molecular Genetics Laboratory, Centre for Cardiovascular Surgery and Transplantation , Brno , Czech Republic
| | - Tomáš Freiberger
- Medical Genomics RG, Central European Institute of Technology, Masaryk University , Brno , Czech Republic.,Molecular Genetics Laboratory, Centre for Cardiovascular Surgery and Transplantation , Brno , Czech Republic.,Faculty of Medicine, Masaryk University , Brno , Czech Republic
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14
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α-Globin pre-mRNA splicing, revisited. Blood 2019; 133:2250-2251. [DOI: 10.1182/blood-2019-03-901108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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15
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Park JE, Cartegni L. In Vitro Modulation of Endogenous Alternative Splicing Using Splice-Switching Antisense Oligonucleotides. Methods Mol Biol 2018; 1648:39-52. [PMID: 28766288 DOI: 10.1007/978-1-4939-7204-3_4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Regulation of alternative splicing can be harnessed by antisense-based compounds to control gene expression. Antisense-mediated splicing interference has become a valuable molecular tool to modulate endogenous alternative splicing patterns, to correct cryptic or aberrant splicing, to reduce gene expression by triggering nonsense-mediated mRNA decay, and to activate intronic polyadenylation, both in vitro and in vivo. Here, we describe methods to induce and analyze the modulation of RNA processing, using modified splice-switching antisense oligonucleotides, such as phosphorodiamidate morpholino (PMO).
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Affiliation(s)
- Jeong Eun Park
- Susan Lehman Cullman Laboratory for Cancer Research, Ernest Mario School of Pharmacy, Rutgers, The State University of New Jersey, Piscataway, NJ, USA
| | - Luca Cartegni
- Susan Lehman Cullman Laboratory for Cancer Research, Ernest Mario School of Pharmacy, Rutgers, The State University of New Jersey, Piscataway, NJ, USA.
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16
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Lin P, Luo Y, Zhu S, Maggio D, Yang H, Hu C, Wang J, Zhang H, Ren Y, Zhou X, Mei C, Ma L, Xu W, Ye L, Zhuang Z, Jin J, Tong H. Isocitrate dehydrogenase 2 mutations correlate with leukemic transformation and are predicted by 2-hydroxyglutarate in myelodysplastic syndromes. J Cancer Res Clin Oncol 2018; 144:1037-1047. [PMID: 29549529 DOI: 10.1007/s00432-018-2627-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Accepted: 03/12/2018] [Indexed: 12/01/2022]
Abstract
PURPOSE The myelodysplastic syndromes (MDS) are a group of hematologic disorders characterized by the presence of somatically mutated hematopoietic stem cells (HSCs) that increase the risk of progression to secondary acute myeloid leukemia (sAML). Mutations in isocitrate dehydrogenase (IDHmut) are thought to correlate with the increased production of the oncogenic protein 2-hydroxyglutarate (2-HG) in AML. The aim of this study was to examine whether serum 2-HG has utility as a prognostic biomarker, and whether elevated 2-HG levels are predictive of IDH mutations in patients with MDS. METHODS Genetic profiling was utilized to determine the genetic composition of a large cohort of MDS patients, including the presence or absence of IDH1 or IDH2 mutations (n = 281). Serum 2-HG levels were detected by liquid chromatography-tandem mass spectrometry. RESULTS In the current study of MDS patients, elevated serum 2-HG levels were predictive of inferior overall- and leukemia-free survival irrespective of IPSS risk grouping. Higher serum 2-HG levels predicted the presence of IDH mutations. IDH2mut patients had a higher risk of leukemic transformation. The co-occurrence of DNMT3A or SRSF2 mutations was found to be increased in IDH2mut patients. IDH2 mutations were associated with significantly worse OS and LFS amongst patients with low-risk MDS by IPSS grouping. CONCLUSIONS The noted predictive value of serum 2-HG levels and IDH2 mutations on OS and LFS support the use of biomarkers and/or underlying cytogenetics in novel prognostic scoring systems for MDS.
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Affiliation(s)
- Peipei Lin
- Department of Hematology, The First Affiliated Hospital, Zhejiang University, No. 79 Qingchun Road, Hangzhou, 310003, People's Republic of China.,Myelodysplastic Syndromes Diagnosis and Therapy center, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China.,Institute of Hematology, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China
| | - Yingwan Luo
- Department of Hematology, The First Affiliated Hospital, Zhejiang University, No. 79 Qingchun Road, Hangzhou, 310003, People's Republic of China.,Myelodysplastic Syndromes Diagnosis and Therapy center, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China.,Institute of Hematology, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China
| | - Shuanghong Zhu
- Department of Hematology, The First Affiliated Hospital, Zhejiang University, No. 79 Qingchun Road, Hangzhou, 310003, People's Republic of China.,Myelodysplastic Syndromes Diagnosis and Therapy center, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China.,Institute of Hematology, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China
| | - Dominic Maggio
- Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - Haiyang Yang
- Department of Hematology, The First Affiliated Hospital, Zhejiang University, No. 79 Qingchun Road, Hangzhou, 310003, People's Republic of China.,Myelodysplastic Syndromes Diagnosis and Therapy center, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China.,Institute of Hematology, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China
| | - Chao Hu
- Department of Hematology, The First Affiliated Hospital, Zhejiang University, No. 79 Qingchun Road, Hangzhou, 310003, People's Republic of China.,Institute of Hematology, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China
| | - Jinghan Wang
- Department of Hematology, The First Affiliated Hospital, Zhejiang University, No. 79 Qingchun Road, Hangzhou, 310003, People's Republic of China.,Institute of Hematology, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China
| | - Hua Zhang
- Department of Hematology, The First Affiliated Hospital, Zhejiang University, No. 79 Qingchun Road, Hangzhou, 310003, People's Republic of China.,Myelodysplastic Syndromes Diagnosis and Therapy center, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China.,Institute of Hematology, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China
| | - Yanling Ren
- Department of Hematology, The First Affiliated Hospital, Zhejiang University, No. 79 Qingchun Road, Hangzhou, 310003, People's Republic of China.,Myelodysplastic Syndromes Diagnosis and Therapy center, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China.,Institute of Hematology, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China
| | - Xinping Zhou
- Department of Hematology, The First Affiliated Hospital, Zhejiang University, No. 79 Qingchun Road, Hangzhou, 310003, People's Republic of China.,Myelodysplastic Syndromes Diagnosis and Therapy center, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China.,Institute of Hematology, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China
| | - Chen Mei
- Department of Hematology, The First Affiliated Hospital, Zhejiang University, No. 79 Qingchun Road, Hangzhou, 310003, People's Republic of China.,Myelodysplastic Syndromes Diagnosis and Therapy center, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China.,Institute of Hematology, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China
| | - Liya Ma
- Department of Hematology, The First Affiliated Hospital, Zhejiang University, No. 79 Qingchun Road, Hangzhou, 310003, People's Republic of China.,Myelodysplastic Syndromes Diagnosis and Therapy center, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China.,Institute of Hematology, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China
| | - Weilai Xu
- Department of Hematology, The First Affiliated Hospital, Zhejiang University, No. 79 Qingchun Road, Hangzhou, 310003, People's Republic of China.,Myelodysplastic Syndromes Diagnosis and Therapy center, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China.,Institute of Hematology, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China
| | - Li Ye
- Department of Hematology, The First Affiliated Hospital, Zhejiang University, No. 79 Qingchun Road, Hangzhou, 310003, People's Republic of China.,Myelodysplastic Syndromes Diagnosis and Therapy center, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China.,Institute of Hematology, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China
| | - Zhengping Zhuang
- Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - Jie Jin
- Department of Hematology, The First Affiliated Hospital, Zhejiang University, No. 79 Qingchun Road, Hangzhou, 310003, People's Republic of China.,Institute of Hematology, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China
| | - Hongyan Tong
- Department of Hematology, The First Affiliated Hospital, Zhejiang University, No. 79 Qingchun Road, Hangzhou, 310003, People's Republic of China. .,Myelodysplastic Syndromes Diagnosis and Therapy center, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China. .,Institute of Hematology, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China.
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17
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Targeting Splicing in the Treatment of Myelodysplastic Syndromes and Other Myeloid Neoplasms. Curr Hematol Malig Rep 2017; 11:408-415. [PMID: 27492253 DOI: 10.1007/s11899-016-0344-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Genome sequencing of primary cells from patients with myelodysplastic syndromes (MDS) led to the identification of recurrent heterozygous mutations in gene encoding components of the spliceosome, the cellular machinery which processes pre-messenger RNA (mRNA) to mature mRNA during gene transcription. Splicing mutations are mutually exclusive with one another and collectively represent the most common mutation class in MDS, occurring in approximately 60 % of patients overall and more than 80 % of those with ring sideroblasts. Evidence from animal models suggests that homozygous splicing mutations are lethal, and that in heterozygously mutated models, any further disruption of splicing triggers apoptosis and cell death. MDS cells with spliceosome mutations are thus uniquely vulnerable to therapies targeting splicing, which may be tolerated by healthy cells. The spliceosome is emerging as a novel therapeutic target in MDS and related myeloid neoplasms, with the first clinical trial of a splicing modulator opening in 2016.
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18
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Armstrong RN, Steeples V, Singh S, Sanchi A, Boultwood J, Pellagatti A. Splicing factor mutations in the myelodysplastic syndromes: target genes and therapeutic approaches. Adv Biol Regul 2017; 67:13-29. [PMID: 28986033 DOI: 10.1016/j.jbior.2017.09.008] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2017] [Revised: 09/19/2017] [Accepted: 09/21/2017] [Indexed: 10/25/2022]
Abstract
Mutations in splicing factor genes (SF3B1, SRSF2, U2AF1 and ZRSR2) are frequently found in patients with myelodysplastic syndromes (MDS), suggesting that aberrant spliceosome function plays a key role in the pathogenesis of MDS. Splicing factor mutations have been shown to result in aberrant splicing of many downstream target genes. Recent functional studies have begun to characterize the splicing dysfunction in MDS, identifying some key aberrantly spliced genes that are implicated in disease pathophysiology. These findings have led to the development of therapeutic strategies using splicing-modulating agents and rapid progress is being made in this field. Splicing inhibitors are promising agents that exploit the preferential sensitivity of splicing factor-mutant cells to these compounds. Here, we review the known target genes associated with splicing factor mutations in MDS, and discuss the potential of splicing-modulating therapies for these disorders.
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Affiliation(s)
- Richard N Armstrong
- Bloodwise Molecular Haematology Unit, Nuffield Division of Clinical Laboratory Sciences, Radcliffe Department of Medicine, University of Oxford, and Oxford BRC Haematology Theme, Oxford, UK
| | - Violetta Steeples
- Bloodwise Molecular Haematology Unit, Nuffield Division of Clinical Laboratory Sciences, Radcliffe Department of Medicine, University of Oxford, and Oxford BRC Haematology Theme, Oxford, UK
| | - Shalini Singh
- Bloodwise Molecular Haematology Unit, Nuffield Division of Clinical Laboratory Sciences, Radcliffe Department of Medicine, University of Oxford, and Oxford BRC Haematology Theme, Oxford, UK
| | - Andrea Sanchi
- Bloodwise Molecular Haematology Unit, Nuffield Division of Clinical Laboratory Sciences, Radcliffe Department of Medicine, University of Oxford, and Oxford BRC Haematology Theme, Oxford, UK
| | - Jacqueline Boultwood
- Bloodwise Molecular Haematology Unit, Nuffield Division of Clinical Laboratory Sciences, Radcliffe Department of Medicine, University of Oxford, and Oxford BRC Haematology Theme, Oxford, UK.
| | - Andrea Pellagatti
- Bloodwise Molecular Haematology Unit, Nuffield Division of Clinical Laboratory Sciences, Radcliffe Department of Medicine, University of Oxford, and Oxford BRC Haematology Theme, Oxford, UK.
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19
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Mutations of RNA splicing factors in hematological malignancies. Cancer Lett 2017; 409:1-8. [PMID: 28888996 DOI: 10.1016/j.canlet.2017.08.042] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Revised: 08/22/2017] [Accepted: 08/28/2017] [Indexed: 01/01/2023]
Abstract
Systematic large-scale cancer genomic studies have produced numerous significant findings. These studies have not only revealed new cancer-promoting genes, but they also have identified cancer-promoting functions of previously known "housekeeping" genes. These studies have identified numerous mutations in genes which play a fundamental role in nuclear precursor mRNA splicing. Somatic mutations and copy number variation in many of the splicing factors which participate in the formation of multiple spliceosomal complexes appear to play a role in many cancers and in particular in myelodysplastic syndromes (MDS). Mutated proteins seem to interfere with the recognition of the authentic splice sites (SS) leading to utilization of suboptimal alternative splicing sites generating aberrantly spliced mRNA isoforms. This short review is focusing on the function of the splice factors involved in the formation of splicing complexes and potential mechanisms which affect usage of the authentic splice site recognition.
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20
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Liu J, Bhadra M, Sinnakannu JR, Yue WL, Tan CW, Rigo F, Ong ST, Roca X. Overcoming imatinib resistance conferred by the BIM deletion polymorphism in chronic myeloid leukemia with splice-switching antisense oligonucleotides. Oncotarget 2017; 8:77567-77585. [PMID: 29100409 PMCID: PMC5652800 DOI: 10.18632/oncotarget.20658] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Accepted: 07/25/2017] [Indexed: 11/25/2022] Open
Abstract
Many tyrosine kinase-driven cancers, including chronic myeloid leukemia (CML), are characterized by high response rates to specific tyrosine kinase inhibitors (TKIs) like imatinib. In East Asians, primary imatinib resistance is caused by a deletion polymorphism in Intron 2 of the BIM gene, whose product is required for TKI-induced apoptosis. The deletion biases BIM splicing from exon 4 to exon 3, generating splice isoforms lacking the exon 4-encoded pro-apoptotic BH3 domain, which impairs the ability of TKIs to induce apoptosis. We sought to identify splice-switching antisense oligonucleotides (ASOs) that block exon 3 but enhance exon 4 splicing, and thereby resensitize BIM deletion-containing cancers to imatinib. First, we mapped multiple cis-acting splicing elements around BIM exon 3 by minigene mutations, and found an exonic splicing enhancer acting via SRSF1. Second, by a systematic ASO walk, we isolated ASOs that corrected the aberrant BIM splicing. Eight of 67 ASOs increased exon 4 levels in BIM deletion-containing cells, and restored imatinib-induced apoptosis and TKI sensitivity. This proof-of-principle study proves that resistant CML cells by BIM deletion polymorphism can be resensitized to imatinib via splice-switching BIM ASOs. Future optimizations might yield a therapeutic ASO as precision-medicine adjuvant treatment for BIM-polymorphism-associated TKI-resistant CML and other cancers.
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Affiliation(s)
- Jun Liu
- School of Biological Sciences, Nanyang Technological University, Singapore
| | - Malini Bhadra
- School of Biological Sciences, Nanyang Technological University, Singapore
| | | | - Wan Lin Yue
- School of Biological Sciences, Nanyang Technological University, Singapore.,CN Yang Scholars Programme, Nanyang Technological University, Singapore
| | - Cheryl Weiqi Tan
- School of Biological Sciences, Nanyang Technological University, Singapore
| | - Frank Rigo
- Ionis Pharmaceuticals, Carlsbad, California, USA
| | - S Tiong Ong
- Cancer and Stem Cell Biology Signature Research Programme, Duke-NUS Medical School, Singapore.,Department of Haematology, Singapore General Hospital, Singapore.,Department of Medical Oncology, National Cancer Centre Singapore, Singapore.,Department of Medicine, Duke University Medical Center, Durham, North Carolina, USA
| | - Xavier Roca
- School of Biological Sciences, Nanyang Technological University, Singapore
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21
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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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22
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Pellagatti A, Boultwood J. Splicing factor gene mutations in the myelodysplastic syndromes: impact on disease phenotype and therapeutic applications. Adv Biol Regul 2016; 63:59-70. [PMID: 27639445 DOI: 10.1016/j.jbior.2016.08.001] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Revised: 08/18/2016] [Accepted: 08/18/2016] [Indexed: 01/05/2023]
Abstract
Splicing factor gene mutations are the most frequent mutations found in patients with the myeloid malignancy myelodysplastic syndrome (MDS), suggesting that spliceosomal dysfunction plays a major role in disease pathogenesis. The aberrantly spliced target genes and deregulated cellular pathways associated with the commonly mutated splicing factor genes in MDS (SF3B1, SRSF2 and U2AF1) are being identified, illuminating the molecular mechanisms underlying MDS. Emerging data from mouse modeling studies indicate that the presence of splicing factor gene mutations can lead to bone marrow hematopoietic stem/myeloid progenitor cell expansion, impaired hematopoiesis and dysplastic differentiation that are hallmarks of MDS. Importantly, recent evidence suggests that spliceosome inhibitors and splicing modulators may have therapeutic value in the treatment of splicing factor mutant myeloid malignancies.
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Affiliation(s)
- Andrea Pellagatti
- Bloodwise Molecular Haematology Unit, Nuffield Division of Clinical Laboratory Sciences, Radcliffe Department of Medicine, University of Oxford; NIHR Biomedical Research Centre, Oxford, UK.
| | - Jacqueline Boultwood
- Bloodwise Molecular Haematology Unit, Nuffield Division of Clinical Laboratory Sciences, Radcliffe Department of Medicine, University of Oxford; NIHR Biomedical Research Centre, Oxford, UK.
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23
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Abstract
The recent genomic characterization of cancers has revealed recurrent somatic point mutations and copy number changes affecting genes encoding RNA splicing factors. Initial studies of these 'spliceosomal mutations' suggest that the proteins bearing these mutations exhibit altered splice site and/or exon recognition preferences relative to their wild-type counterparts, resulting in cancer-specific mis-splicing. Such changes in the splicing machinery may create novel vulnerabilities in cancer cells that can be therapeutically exploited using compounds that can influence the splicing process. Further studies to dissect the biochemical, genomic and biological effects of spliceosomal mutations are crucial for the development of cancer therapies targeted at these mutations.
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Affiliation(s)
- Heidi Dvinge
- Computational Biology Program, Public Health Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA, 98109, USA
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Eunhee Kim
- Human Oncology and Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, NY, 10065, USA
| | - Omar Abdel-Wahab
- Human Oncology and Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, NY, 10065, USA
- Leukemia Service, Dept. of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY, 10065, USA
| | - Robert K. Bradley
- Computational Biology Program, Public Health Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA, 98109, USA
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
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24
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Delatte B, Wang F, Ngoc LV, Collignon E, Bonvin E, Deplus R, Calonne E, Hassabi B, Putmans P, Awe S, Wetzel C, Kreher J, Soin R, Creppe C, Limbach PA, Gueydan C, Kruys V, Brehm A, Minakhina S, Defrance M, Steward R, Fuks F. RNA biochemistry. Transcriptome-wide distribution and function of RNA hydroxymethylcytosine. Science 2016; 351:282-5. [PMID: 26816380 DOI: 10.1126/science.aac5253] [Citation(s) in RCA: 289] [Impact Index Per Article: 36.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Hydroxymethylcytosine, well described in DNA, occurs also in RNA. Here, we show that hydroxymethylcytosine preferentially marks polyadenylated RNAs and is deposited by Tet in Drosophila. We map the transcriptome-wide hydroxymethylation landscape, revealing hydroxymethylcytosine in the transcripts of many genes, notably in coding sequences, and identify consensus sites for hydroxymethylation. We found that RNA hydroxymethylation can favor mRNA translation. Tet and hydroxymethylated RNA are found to be most abundant in the Drosophila brain, and Tet-deficient fruitflies suffer impaired brain development, accompanied by decreased RNA hydroxymethylation. This study highlights the distribution, localization, and function of cytosine hydroxymethylation and identifies central roles for this modification in Drosophila.
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Affiliation(s)
- Benjamin Delatte
- Laboratory of Cancer Epigenetics, Faculty of Medicine, ULB Cancer Research Center (U-CRC), Université Libre de Bruxelles (ULB), Brussels, Belgium
| | - Fei Wang
- Waksman Institute, Department of Molecular Biology and Biochemistry, Cancer Institute of New Jersey, Rutgers University, Piscataway, NJ, USA
| | - Long Vo Ngoc
- Laboratory of Molecular Biology of the Gene, Faculty of Sciences, Université Libre de Bruxelles, Gosselies, Belgium
| | - Evelyne Collignon
- Laboratory of Cancer Epigenetics, Faculty of Medicine, ULB Cancer Research Center (U-CRC), Université Libre de Bruxelles (ULB), Brussels, Belgium
| | - Elise Bonvin
- Laboratory of Cancer Epigenetics, Faculty of Medicine, ULB Cancer Research Center (U-CRC), Université Libre de Bruxelles (ULB), Brussels, Belgium
| | - Rachel Deplus
- Laboratory of Cancer Epigenetics, Faculty of Medicine, ULB Cancer Research Center (U-CRC), Université Libre de Bruxelles (ULB), Brussels, Belgium
| | - Emilie Calonne
- Laboratory of Cancer Epigenetics, Faculty of Medicine, ULB Cancer Research Center (U-CRC), Université Libre de Bruxelles (ULB), Brussels, Belgium
| | - Bouchra Hassabi
- Laboratory of Cancer Epigenetics, Faculty of Medicine, ULB Cancer Research Center (U-CRC), Université Libre de Bruxelles (ULB), Brussels, Belgium
| | - Pascale Putmans
- Laboratory of Cancer Epigenetics, Faculty of Medicine, ULB Cancer Research Center (U-CRC), Université Libre de Bruxelles (ULB), Brussels, Belgium
| | - Stephan Awe
- Institut für Molekularbiologie und Tumorforschung, Philipps-Universität Marburg, Marburg, Germany
| | - Collin Wetzel
- Department of Chemistry, University of Cincinnati, Cincinnati, OH, USA
| | - Judith Kreher
- Institut für Molekularbiologie und Tumorforschung, Philipps-Universität Marburg, Marburg, Germany
| | - Romuald Soin
- Laboratory of Molecular Biology of the Gene, Faculty of Sciences, Université Libre de Bruxelles, Gosselies, Belgium
| | - Catherine Creppe
- Laboratory of Cancer Epigenetics, Faculty of Medicine, ULB Cancer Research Center (U-CRC), Université Libre de Bruxelles (ULB), Brussels, Belgium
| | - Patrick A Limbach
- Department of Chemistry, University of Cincinnati, Cincinnati, OH, USA
| | - Cyril Gueydan
- Laboratory of Molecular Biology of the Gene, Faculty of Sciences, Université Libre de Bruxelles, Gosselies, Belgium
| | - Véronique Kruys
- Laboratory of Molecular Biology of the Gene, Faculty of Sciences, Université Libre de Bruxelles, Gosselies, Belgium
| | - Alexander Brehm
- Institut für Molekularbiologie und Tumorforschung, Philipps-Universität Marburg, Marburg, Germany
| | - Svetlana Minakhina
- Waksman Institute, Department of Molecular Biology and Biochemistry, Cancer Institute of New Jersey, Rutgers University, Piscataway, NJ, USA
| | - Matthieu Defrance
- Laboratory of Cancer Epigenetics, Faculty of Medicine, ULB Cancer Research Center (U-CRC), Université Libre de Bruxelles (ULB), Brussels, Belgium
| | - Ruth Steward
- Waksman Institute, Department of Molecular Biology and Biochemistry, Cancer Institute of New Jersey, Rutgers University, Piscataway, NJ, USA
| | - François Fuks
- Laboratory of Cancer Epigenetics, Faculty of Medicine, ULB Cancer Research Center (U-CRC), Université Libre de Bruxelles (ULB), Brussels, Belgium.
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25
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Skrdlant L, Lin RJ. Characterization of RNA-Protein Interactions: Lessons from Two RNA-Binding Proteins, SRSF1 and SRSF2. Methods Mol Biol 2016; 1421:1-13. [PMID: 26965252 DOI: 10.1007/978-1-4939-3591-8_1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
SR proteins are a class of RNA-binding proteins whose RNA-binding ability is required for both constitutive and alternative splicing. While members of the SR protein family were once thought to have redundant functions, in-depth biochemical analysis of their RNA-binding abilities has revealed distinct binding profiles for each SR protein, that often lead to either synergistic or antagonistic functions. SR protein family members SRSF1 and SRSF2 are two of the most highly studied RNA-binding proteins. Here we examine the various methods used to differentiate SRSF1 and SRSF2 RNA-binding ability. We discuss the benefits and type of information that can be determined using each method.
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Affiliation(s)
- Lindsey Skrdlant
- Irell & Manella Graduate School of Biological Sciences of the City of Hope, Duarte, CA, USA
- Department of Molecular and Cellular Biology, Beckman Research Institute of the City of Hope, 1500 E. Duarte Road, Duarte, CA, 91010, USA
| | - Ren-Jang Lin
- Irell & Manella Graduate School of Biological Sciences of the City of Hope, Duarte, CA, USA.
- Department of Molecular and Cellular Biology, Beckman Research Institute of the City of Hope, 1500 E. Duarte Road, Duarte, CA, 91010, USA.
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Disease-associated mutation in SRSF2 misregulates splicing by altering RNA-binding affinities. Proc Natl Acad Sci U S A 2015; 112:E4726-34. [PMID: 26261309 DOI: 10.1073/pnas.1514105112] [Citation(s) in RCA: 149] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Serine/arginine-rich splicing factor 2 (SRSF2) is an RNA-binding protein that plays important roles in splicing of mRNA precursors. SRSF2 mutations are frequently found in patients with myelodysplastic syndromes and certain leukemias, but how these mutations affect SRSF2 function has only begun to be examined. We used clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein-9 nuclease to introduce the P95H mutation to SRSF2 in K562 leukemia cells, generating an isogenic model so that splicing alterations can be attributed solely to mutant SRSF2. We found that SRSF2 (P95H) misregulates 548 splicing events (<1% of total). Of these events, 374 involved the inclusion of cassette exons, and the inclusion was either increased (206) or decreased (168). We detected a specific motif (UCCA/UG) enriched in the more-included exons and a distinct motif (UGGA/UG) in the more-excluded exons. RNA gel shift assays showed that a mutant SRSF2 derivative bound more tightly than its wild-type counterpart to RNA sites containing UCCAG but bound less tightly to UGGAG sites. Thus in most cases the pattern of exon inclusion or exclusion correlated with stronger or weaker RNA binding, respectively. We further show that the P95H mutation does not affect other functions of SRSF2, i.e., protein-protein interactions with key splicing factors. Our results thus demonstrate that the P95H mutation positively or negatively alters the binding affinity of SRSF2 for cognate RNA sites in target transcripts, leading to misregulation of exon inclusion. Our findings shed light on the mechanism of the disease-associated SRSF2 mutation in splicing regulation and also reveal a group of misspliced mRNA isoforms for potential therapeutic targeting.
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27
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Kim E, Ilagan JO, Liang Y, Daubner GM, Lee SCW, Ramakrishnan A, Li Y, Chung YR, Micol JB, Murphy ME, Cho H, Kim MK, Zebari AS, Aumann S, Park CY, Buonamici S, Smith PG, Deeg HJ, Lobry C, Aifantis I, Modis Y, Allain FHT, Halene S, Bradley RK, Abdel-Wahab O. SRSF2 Mutations Contribute to Myelodysplasia by Mutant-Specific Effects on Exon Recognition. Cancer Cell 2015; 27:617-30. [PMID: 25965569 PMCID: PMC4429920 DOI: 10.1016/j.ccell.2015.04.006] [Citation(s) in RCA: 410] [Impact Index Per Article: 45.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Revised: 02/19/2015] [Accepted: 04/10/2015] [Indexed: 12/14/2022]
Abstract
Mutations affecting spliceosomal proteins are the most common mutations in patients with myelodysplastic syndromes (MDS), but their role in MDS pathogenesis has not been delineated. Here we report that mutations affecting the splicing factor SRSF2 directly impair hematopoietic differentiation in vivo, which is not due to SRSF2 loss of function. By contrast, SRSF2 mutations alter SRSF2's normal sequence-specific RNA binding activity, thereby altering the recognition of specific exonic splicing enhancer motifs to drive recurrent mis-splicing of key hematopoietic regulators. This includes SRSF2 mutation-dependent splicing of EZH2, which triggers nonsense-mediated decay, which, in turn, results in impaired hematopoietic differentiation. These data provide a mechanistic link between a mutant spliceosomal protein, alterations in the splicing of key regulators, and impaired hematopoiesis.
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Affiliation(s)
- Eunhee Kim
- Human Oncology and Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Janine O Ilagan
- Computational Biology Program, Public Health Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA; Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Yang Liang
- Hematology, Yale Comprehensive Cancer Center and Department of Internal Medicine, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Gerrit M Daubner
- Institute for Molecular Biology and Biophysics, ETH, 8093 Zürich, Switzerland
| | - Stanley C-W Lee
- Human Oncology and Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Aravind Ramakrishnan
- Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA; Division of Medical Oncology, School of Medicine, University of Washington, Seattle, WA 98109, USA
| | - Yue Li
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520, USA
| | - Young Rock Chung
- Human Oncology and Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Jean-Baptiste Micol
- Human Oncology and Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Michele E Murphy
- Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Hana Cho
- Human Oncology and Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Min-Kyung Kim
- Human Oncology and Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Ahmad S Zebari
- Computational Biology Program, Public Health Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA; Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Shlomzion Aumann
- Human Oncology and Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Christopher Y Park
- Human Oncology and Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA; Department of Pathology, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | | | | | - H Joachim Deeg
- Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA; Division of Medical Oncology, School of Medicine, University of Washington, Seattle, WA 98109, USA
| | - Camille Lobry
- Institut National de la Santé et de la Recherche Medicale (INSERM) U1009, Institut Gustave Roussy, 94805 Villejuif, France; Université Paris-Sud, 91400 Orsay, France
| | - Iannis Aifantis
- Howard Hughes Medical Institute and Department of Pathology, New York University School of Medicine, New York, NY 10016, USA
| | - Yorgo Modis
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520, USA; Department of Medicine, University of Cambridge, MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, UK
| | - Frederic H-T Allain
- Institute for Molecular Biology and Biophysics, ETH, 8093 Zürich, Switzerland
| | - Stephanie Halene
- Hematology, Yale Comprehensive Cancer Center and Department of Internal Medicine, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Robert K Bradley
- Computational Biology Program, Public Health Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA; Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA.
| | - Omar Abdel-Wahab
- Human Oncology and Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA; Leukemia Service, Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA.
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Decoding mechanisms by which silent codon changes influence protein biogenesis and function. Int J Biochem Cell Biol 2015; 64:58-74. [PMID: 25817479 DOI: 10.1016/j.biocel.2015.03.011] [Citation(s) in RCA: 90] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Revised: 03/02/2015] [Accepted: 03/14/2015] [Indexed: 02/07/2023]
Abstract
SCOPE Synonymous codon usage has been a focus of investigation since the discovery of the genetic code and its redundancy. The occurrences of synonymous codons vary between species and within genes of the same genome, known as codon usage bias. Today, bioinformatics and experimental data allow us to compose a global view of the mechanisms by which the redundancy of the genetic code contributes to the complexity of biological systems from affecting survival in prokaryotes, to fine tuning the structure and function of proteins in higher eukaryotes. Studies analyzing the consequences of synonymous codon changes in different organisms have revealed that they impact nucleic acid stability, protein levels, structure and function without altering amino acid sequence. As such, synonymous mutations inevitably contribute to the pathogenesis of complex human diseases. Yet, fundamental questions remain unresolved regarding the impact of silent mutations in human disorders. In the present review we describe developments in this area concentrating on mechanisms by which synonymous mutations may affect protein function and human health. PURPOSE This synopsis illustrates the significance of synonymous mutations in disease pathogenesis. We review the different steps of gene expression affected by silent mutations, and assess the benefits and possible harmful effects of codon optimization applied in the development of therapeutic biologics. PHYSIOLOGICAL AND MEDICAL RELEVANCE Understanding mechanisms by which synonymous mutations contribute to complex diseases such as cancer, neurodegeneration and genetic disorders, including the limitations of codon-optimized biologics, provides insight concerning interpretation of silent variants and future molecular therapies.
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Guyot M, Pagès G. VEGF Splicing and the Role of VEGF Splice Variants: From Physiological-Pathological Conditions to Specific Pre-mRNA Splicing. Methods Mol Biol 2015; 1332:3-23. [PMID: 26285742 DOI: 10.1007/978-1-4939-2917-7_1] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
During this past decade, the vascular endothelial growth factor (VEGF) pathway has been extensively studied. VEGF is a paradigm of molecular regulation since its expression is controlled at all possible steps including transcription, mRNA stability, translation, and pre-mRNA splicing. The latter form of molecular regulation is probably the least studied. This field has been neglected; yet different forms of VEGF with different sizes and different physiological properties issued from alternative splicing have been described a long time ago. Recently a new level of complexity was added to the field of splicing of VEGF pre-mRNA. Whereas thousands of publications have described VEGF as a pro-angiogenic factor, an alternative splicing event generates specific anti-angiogenic forms of VEGF that only differ from the others by a modification in the last six amino acids of the protein. According to the scientists who discovered these isoforms, which are indistinguishable from the pro-angiogenic ones with pan VEGF antibodies, some of the literature on VEGF is at least inexact if not completely false. Moreover, the presence of anti-angiogenic forms of VEGF may explain the disappointing efficacy of anti-VEGF therapies on the overall survival of patients with different forms of cancers and with wet age-related macular degeneration. This review focuses on the existence of the different alternative splice variants of VEGF and the molecular mechanisms associated with their expression and function.
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Affiliation(s)
- Mélanie Guyot
- Institute for Research on Cancer and Aging of Nice (IRCAN), University of Nice Sophia Antipolis, Centre Antoine Lacassagne 33 Avenue de Valombrose, UMR CNRS 7284/INSERM U 1081, Nice, 06189, France
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Machinaga A, Takase-Yoden S. A 38 nt region and its flanking sequences within gag of Friend murine leukemia virus are crucial for splicing at the correct 5' and 3' splice sites. Microbiol Immunol 2014; 58:38-50. [PMID: 24236664 DOI: 10.1111/1348-0421.12114] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2013] [Revised: 10/25/2013] [Accepted: 11/12/2013] [Indexed: 11/27/2022]
Abstract
The genome of the Friend murine leukemia virus (Fr-MLV) contains a 5' splice site (5'ss) located at 205 nt and a 3'ss located at 5489 nt. In our previous studies, it was shown that if the HindIII-BglII (879-1904 bp) fragment within gag is deleted from the proA8m1 vector, which carries the entire Fr-MLV sequence, then cryptic splicing of env-mRNA occurs. Here, attempts were made to identify the genomic segment(s) in this region that is/are essential to correct splicing. First, vectors with a serially truncated HindIII-BglII fragment were constructed. The vector, in which a 38 bp fragment (1612-1649 bp) is deleted or reversed in proA8m1, only produced splice variants. It was found that a 38 nt region within gag contains important elements that positively regulate splicing at the correct splice sites. Further analyses of a series of vectors carrying the 38 bp fragment and its flanking sequences showed that a region (1183-1611 nt) upstream of the 38 nt fragment also contains sequences that positively or negatively influence splicing at the correct splice sites. The SphI-NdeI (5140-5400 bp) fragment just upstream of the 3'ss was deleted from vectors that carried the 38 bp fragment and its flanking sequences, which yielded correctly spliced mRNA; interestingly, these deleted vectors showed cryptic splicing. These findings suggest that the 5140-5400 nt region located just upstream of the 3'ss is required for the splicing function of the 38 nt fragment and its flanking sequences.
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Affiliation(s)
- Akihito Machinaga
- Department of Bioinformatics, Faculty of Engineering, Soka University, 1-236, Tangi-machi, Hachioji, Tokyo, 192-8577, 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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32
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Ma Y, Wang C, Li B, Qin L, Su J, Yang M, He S. Bcl-2-associated transcription factor 1 interacts with fragile X-related protein 1. Acta Biochim Biophys Sin (Shanghai) 2014; 46:119-27. [PMID: 24389646 PMCID: PMC7109863 DOI: 10.1093/abbs/gmt134] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The absence of fragile X mental retardation protein (FMRP) causes fragile X syndrome (FXS), which is the leading cause of hereditary mental retardation. Fragile X-related protein 1 (FXR1P), which plays an important role in normal muscle development, is one of the two autosomal paralogs of FMRP. To understand the functions of FXR1P, we screened FXR1P-interacting proteins by using a yeast two-hybrid system. The fragile X-related gene 1 (FXR1) was fused to pGBKT7 and then used as the bait to screen the human fetal brain cDNA library. The screening results revealed 10 FXR1P-interacting proteins including Bcl-2-associated transcription factor 1 (BTF). The interaction between FXR1P and BTF was confirmed by using both β-galactosidase assay and growth test in selective media. Co-immunoprecipitation assay in mammalian cells was also carried out to confirm the FXR1P/BTF interaction. Moreover, we confirmed that BTF co-localized with FXR1P in the cytoplasm around the nucleus in rat vascular smooth muscle cells by using confocal fluorescence microscopy. These results provide clues to elucidate the relationship between FXR1P and FXS.
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Affiliation(s)
- Yun Ma
- Department of Biochemistry and Biology, South China University, Hengyang 421001, China
| | - Changbo Wang
- Department of Biochemistry and Biology, South China University, Hengyang 421001, China
| | - Binyuan Li
- Department of Biochemistry and Biology, South China University, Hengyang 421001, China
| | - Lingxue Qin
- Department of Biochemistry and Biology, South China University, Hengyang 421001, China
| | - Jiao Su
- Department of Biochemistry and Biology, South China University, Hengyang 421001, China
| | - Manjun Yang
- Department of Biochemistry and Biology, South China University, Hengyang 421001, China
| | - Shuya He
- Department of Biochemistry and Biology, South China University, Hengyang 421001, China
- Correspondence address. Tel: +86-13807348502; E-mail:
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Xiang S, Gapsys V, Kim HY, Bessonov S, Hsiao HH, Möhlmann S, Klaukien V, Ficner R, Becker S, Urlaub H, Lührmann R, de Groot B, Zweckstetter M. Phosphorylation drives a dynamic switch in serine/arginine-rich proteins. Structure 2013; 21:2162-74. [PMID: 24183573 DOI: 10.1016/j.str.2013.09.014] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2013] [Revised: 09/25/2013] [Accepted: 09/27/2013] [Indexed: 11/25/2022]
Abstract
Serine/arginine-rich (SR) proteins are important players in RNA metabolism and are extensively phosphorylated at serine residues in RS repeats. Here, we show that phosphorylation switches the RS domain of the serine/arginine-rich splicing factor 1 from a fully disordered state to a partially rigidified arch-like structure. Nuclear magnetic resonance spectroscopy in combination with molecular dynamics simulations revealed that the conformational switch is restricted to RS repeats, critically depends on the phosphate charge state and strongly decreases the conformational entropy of RS domains. The dynamic switch also occurs in the 100 kDa SR-related protein hPrp28, for which phosphorylation at the RS repeat is required for spliceosome assembly. Thus, a phosphorylation-induced dynamic switch is common to the class of serine/arginine-rich proteins and provides a molecular basis for the functional redundancy of serine/arginine-rich proteins and the profound influence of RS domain phosphorylation on protein-protein and protein-RNA interactions.
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Affiliation(s)
- Shengqi Xiang
- Department of NMR-based Structural Biology, Max Planck Institute for Biophysical Chemistry, Göttingen 37077, Germany
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Role of pseudoexons and pseudointrons in human cancer. Int J Cell Biol 2013; 2013:810572. [PMID: 24204383 PMCID: PMC3800588 DOI: 10.1155/2013/810572] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2013] [Accepted: 08/09/2013] [Indexed: 11/18/2022] Open
Abstract
In all eukaryotic organisms, pre-mRNA splicing and alternative splicing processes play an essential role in regulating the flow of information required to drive complex developmental and metabolic pathways. As a result, eukaryotic cells have developed a very efficient macromolecular machinery, called the spliceosome, to correctly recognize the pre-mRNA sequences that need to be inserted in a mature mRNA (exons) from those that should be removed (introns). In healthy individuals, alternative and constitutive splicing processes function with a high degree of precision and fidelity in order to ensure the correct working of this machinery. In recent years, however, medical research has shown that alterations at the splicing level play an increasingly important role in many human hereditary diseases, neurodegenerative processes, and especially in cancer origin and progression. In this minireview, we will focus on several genes whose association with cancer has been well established in previous studies, such as ATM, BRCA1/A2, and NF1. In particular, our objective will be to provide an overview of the known mechanisms underlying activation/repression of pseudoexons and pseudointrons; the possible utilization of these events as biomarkers of tumor staging/grading; and finally, the treatment options for reversing pathologic splicing events.
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Morata J, Béjar S, Talavera D, Riera C, Lois S, de Xaxars GM, de la Cruz X. The relationship between gene isoform multiplicity, number of exons and protein divergence. PLoS One 2013; 8:e72742. [PMID: 24023641 PMCID: PMC3758341 DOI: 10.1371/journal.pone.0072742] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2013] [Accepted: 07/14/2013] [Indexed: 11/18/2022] Open
Abstract
At present we know that phenotypic differences between organisms arise from a variety of sources, like protein sequence divergence, regulatory sequence divergence, alternative splicing, etc. However, we do not have yet a complete view of how these sources are related. Here we address this problem, studying the relationship between protein divergence and the ability of genes to express multiple isoforms. We used three genome-wide datasets of human-mouse orthologs to study the relationship between isoform multiplicity co-occurrence between orthologs (the fact that two orthologs have more than one isoform) and protein divergence. In all cases our results showed that there was a monotonic dependence between these two properties. We could explain this relationship in terms of a more fundamental one, between exon number of the largest isoform and protein divergence. We found that this last relationship was present, although with variations, in other species (chimpanzee, cow, rat, chicken, zebrafish and fruit fly). In summary, we have identified a relationship between protein divergence and isoform multiplicity co-occurrence and explained its origin in terms of a simple gene-level property. Finally, we discuss the biological implications of these findings for our understanding of inter-species phenotypic differences.
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Affiliation(s)
- Jordi Morata
- Department of Structural Biology, Institut de Biologia Molecular de Barcelona (IBMB)-Consejo Superior de Investigaciones Científicas (CSIC), Barcelona, Spain
| | - Santi Béjar
- Department of Structural Biology, Institut de Biologia Molecular de Barcelona (IBMB)-Consejo Superior de Investigaciones Científicas (CSIC), Barcelona, Spain
| | - David Talavera
- Faculty of Life Sciences, Manchester University, Manchester, United Kingdom
| | - Casandra Riera
- Laboratory of Translational Bioinformatics in Neuroscience, Vall d'Hebron Institute of Research (VHIR), Barcelona, Spain
| | - Sergio Lois
- Laboratory of Translational Bioinformatics in Neuroscience, Vall d'Hebron Institute of Research (VHIR), Barcelona, Spain
| | - Gemma Mas de Xaxars
- Laboratori de Botànica, Facultat de Farmàcia, Universitat de Barcelona, Barcelona, Spain
| | - Xavier de la Cruz
- Department of Structural Biology, Institut de Biologia Molecular de Barcelona (IBMB)-Consejo Superior de Investigaciones Científicas (CSIC), Barcelona, Spain
- Laboratory of Translational Bioinformatics in Neuroscience, Vall d'Hebron Institute of Research (VHIR), Barcelona, Spain
- Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain
- * E-mail:
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Ji X, Zhou Y, Pandit S, Huang J, Li H, Lin CY, Xiao R, Burge CB, Fu XD. SR proteins collaborate with 7SK and promoter-associated nascent RNA to release paused polymerase. Cell 2013; 153:855-68. [PMID: 23663783 DOI: 10.1016/j.cell.2013.04.028] [Citation(s) in RCA: 244] [Impact Index Per Article: 22.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2012] [Revised: 03/14/2013] [Accepted: 04/15/2013] [Indexed: 10/26/2022]
Abstract
RNAP II is frequently paused near gene promoters in mammals, and its transition to productive elongation requires active recruitment of P-TEFb, a cyclin-dependent kinase for RNAP II and other key transcription elongation factors. A fraction of P-TEFb is sequestered in an inhibitory complex containing the 7SK noncoding RNA, but it has been unclear how P-TEFb is switched from the 7SK complex to RNAP II during transcription activation. We report that SRSF2 (also known as SC35, an SR-splicing factor) is part of the 7SK complex assembled at gene promoters and plays a direct role in transcription pause release. We demonstrate RNA-dependent, coordinated release of SRSF2 and P-TEFb from the 7SK complex and transcription activation via SRSF2 binding to promoter-associated nascent RNA. These findings reveal an unanticipated SR protein function, a role for promoter-proximal nascent RNA in gene activation, and an analogous mechanism to HIV Tat/TAR for activating cellular genes.
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Affiliation(s)
- Xiong Ji
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, Hubei 430072, China
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Anderson ES, Lin CH, Xiao X, Stoilov P, Burge CB, Black DL. The cardiotonic steroid digitoxin regulates alternative splicing through depletion of the splicing factors SRSF3 and TRA2B. RNA (NEW YORK, N.Y.) 2012; 18:1041-9. [PMID: 22456266 PMCID: PMC3334691 DOI: 10.1261/rna.032912.112] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2012] [Accepted: 02/24/2012] [Indexed: 05/24/2023]
Abstract
Modulation of alternative pre-mRNA splicing is a potential approach to therapeutic targeting for a variety of human diseases. We investigated the mechanism by which digitoxin, a member of the cardiotonic steroid class of drugs, regulates alternative splicing. Transcriptome-wide analysis identified a large set of alternative splicing events that change after digitoxin treatment. Within and adjacent to these regulated exons, we identified enrichment of potential binding sites for the splicing factors SRp20 (SRSF3/SFRS3) and Tra2-β (SFRS10/TRA2B). We further find that both of these proteins are depleted from cells by digitoxin treatment. Characterization of SRp20 and Tra2-β splicing targets revealed that many, but not all, digitoxin-induced splicing changes can be attributed to the depletion of one or both of these factors. Re-expression of SRp20 or Tra2-β after digitoxin treatment restores normal splicing of their targets, indicating that the digitoxin effect is directly due to these factors. These results demonstrate that cardiotonic steroids, long prescribed in the clinical treatment of heart failure, have broad effects on the cellular transcriptome through these and likely other RNA binding proteins. The approach described here can be used to identify targets of other potential therapeutics that act as alternative splicing modulators.
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Affiliation(s)
- Erik S. Anderson
- Molecular Biology Interdepartmental Graduate Program
- Medical Scientist Training Program
| | - Chia-Ho Lin
- Microbiology, Immunology and Molecular Genetics
- Howard Hughes Medical Institute
| | - Xinshu Xiao
- Department of Integrative Biology and Physiology
- Molecular Biology Institute, University of California, Los Angeles, California 90095, USA
| | - Peter Stoilov
- Department of Biochemistry, West Virginia University, Morgantown, West Virginia 26506, USA
| | - Christopher B. Burge
- Department of Biology, Massachusetts Institute of Technology, Boston, Massachusetts 02139, USA
| | - Douglas L. Black
- Microbiology, Immunology and Molecular Genetics
- Howard Hughes Medical Institute
- Molecular Biology Institute, University of California, Los Angeles, California 90095, USA
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38
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Daubner GM, Cléry A, Jayne S, Stevenin J, Allain FHT. A syn-anti conformational difference allows SRSF2 to recognize guanines and cytosines equally well. EMBO J 2011; 31:162-74. [PMID: 22002536 DOI: 10.1038/emboj.2011.367] [Citation(s) in RCA: 107] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2011] [Accepted: 09/12/2011] [Indexed: 11/09/2022] Open
Abstract
SRSF2 (SC35) is a key player in the regulation of alternative splicing events and binds degenerated RNA sequences with similar affinity in nanomolar range. We have determined the solution structure of the SRSF2 RRM bound to the 5'-UCCAGU-3' and 5'-UGGAGU-3' RNA, both identified as SRSF2 binding sites in the HIV-1 tat exon 2. RNA recognition is achieved through a novel sandwich-like structure with both termini forming a positively charged cavity to accommodate the four central nucleotides. To bind both RNA sequences equally well, SRSF2 forms a nearly identical network of intermolecular interactions by simply flipping the bases of the two consecutive C or G nucleotides into either anti or syn conformation. We validate this unusual mode of RNA recognition functionally by in-vitro and in-vivo splicing assays and propose a 5'-SSNG-3' (S=C/G) high-affinity binding consensus sequence for SRSF2. In conclusion, in addition to describe for the first time the RNA recognition mode of SRSF2, we provide the precise consensus sequence to identify new putative binding sites for this splicing factor.
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Affiliation(s)
- Gerrit M Daubner
- Institute of Molecular Biology and Biophysics, ETH Zürich, Zürich, Switzerland
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39
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Busch A, Hertel KJ. Evolution of SR protein and hnRNP splicing regulatory factors. WILEY INTERDISCIPLINARY REVIEWS-RNA 2011; 3:1-12. [PMID: 21898828 DOI: 10.1002/wrna.100] [Citation(s) in RCA: 270] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The splicing of pre-mRNAs is an essential step of gene expression in eukaryotes. Introns are removed from split genes through the activities of the spliceosome, a large ribonuclear machine that is conserved throughout the eukaryotic lineage. While unicellular eukaryotes are characterized by less complex splicing, pre-mRNA splicing of multicellular organisms is often associated with extensive alternative splicing that significantly enriches their proteome. The alternative selection of splice sites and exons permits multicellular organisms to modulate gene expression patterns in a cell type-specific fashion, thus contributing to their functional diversification. Alternative splicing is a regulated process that is mainly influenced by the activities of splicing regulators, such as SR proteins or hnRNPs. These modular factors have evolved from a common ancestor through gene duplication events to a diverse group of splicing regulators that mediate exon recognition through their sequence-specific binding to pre-mRNAs. Given the strong correlations between intron expansion, the complexity of pre-mRNA splicing, and the emergence of splicing regulators, it is argued that the increased presence of SR and hnRNP proteins promoted the evolution of alternative splicing through relaxation of the sequence requirements of splice junctions.
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Affiliation(s)
- Anke Busch
- Department of Microbiology and Molecular Genetics, University of California, Irvine, Irvine, CA 92697-4025, USA
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40
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SR proteins induce alternative exon skipping through their activities on the flanking constitutive exons. Mol Cell Biol 2010; 31:793-802. [PMID: 21135118 DOI: 10.1128/mcb.01117-10] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
SR proteins are well known to promote exon inclusion in regulated splicing through exonic splicing enhancers. SR proteins have also been reported to cause exon skipping, but little is known about the mechanism. We previously characterized SRSF1 (SF2/ASF)-dependent exon skipping of the CaMKIIδ gene during heart remodeling. By using mouse embryo fibroblasts derived from conditional SR protein knockout mice, we now show that SR protein-induced exon skipping depends on their prevalent actions on a flanking constitutive exon and requires collaboration of more than one SR protein. These findings, coupled with other established rules for SR proteins, provide a theoretical framework to understand the complex effect of SR protein-regulated splicing in mammalian cells. We further demonstrate that heart-specific CaMKIIδ splicing can be reconstituted in fibroblasts by downregulating SR proteins and upregulating a RBFOX protein and that SR protein overexpression impairs regulated CaMKIIδ splicing and neuronal differentiation in P19 cells, illustrating that SR protein-dependent exon skipping may constitute a key strategy for synergism with other splicing regulators in establishing tissue-specific alternative splicing critical for cell differentiation programs.
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41
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Solis AS, Patton JG. Analysis of SRrp86-regulated alternative splicing: control of c-Jun and IκBβ activity. RNA Biol 2010; 7:486-94. [PMID: 20400856 DOI: 10.4161/rna.7.4.11567] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Previous work led to the hypothesis that SRrp86, a related member of the SR protein superfamily, can interact with and modulate the activity of other SR proteins. Here, we sought to test this hypothesis by examining the effect of changing SRrp86 concentrations on overall alternative splicing patterns. SpliceArrays were used to examine 9,854 splicing events in wild-type cells, cells overexpressing SRrp86, and cells treated with siRNAs to knockdown SRrp86. From among the 500 splicing events exhibiting altered splicing under these conditions, the splicing of c-Jun and IκBβ were validated as being regulated by SRrp86 resulting in altered regulation of their downstream targets. In both cases, functionally distinct isoforms were generated that demonstrate the role SRrp86 plays in controlling alternative splicing.
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Affiliation(s)
- Amanda S Solis
- Department of Biological Sciences, Vanderbilt University, Nashville, TN USA
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Culler SJ, Hoff KG, Voelker RB, Berglund JA, Smolke CD. Functional selection and systematic analysis of intronic splicing elements identify active sequence motifs and associated splicing factors. Nucleic Acids Res 2010; 38:5152-65. [PMID: 20385591 PMCID: PMC2926609 DOI: 10.1093/nar/gkq248] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Despite the critical role of pre-mRNA splicing in generating proteomic diversity and regulating gene expression, the sequence composition and function of intronic splicing regulatory elements (ISREs) have not been well elucidated. Here, we employed a high-throughput in vivo Screening PLatform for Intronic Control Elements (SPLICE) to identify 125 unique ISRE sequences from a random nucleotide library in human cells. Bioinformatic analyses reveal consensus motifs that resemble splicing regulatory elements and binding sites for characterized splicing factors and that are enriched in the introns of naturally occurring spliced genes, supporting their biological relevance. In vivo characterization, including an RNAi silencing study, demonstrate that ISRE sequences can exhibit combinatorial regulatory activity and that multiple trans-acting factors are involved in the regulatory effect of a single ISRE. Our work provides an initial examination into the sequence characteristics and function of ISREs, providing an important contribution to the splicing code.
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Affiliation(s)
- Stephanie J Culler
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA
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43
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Salato VK, Rediske NW, Zhang C, Hastings ML, Munroe SH. An exonic splicing enhancer within a bidirectional coding sequence regulates alternative splicing of an antisense mRNA. RNA Biol 2010; 7:179-90. [PMID: 20200494 DOI: 10.4161/rna.7.2.11182] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The discovery of increasing numbers of genes with overlapping sequences highlights the problem of expression in the context of constraining regulatory elements from more than one gene. This study identifies regulatory sequences encompassed within two genes that overlap in an antisense orientation at their 3' ends. The genes encode the alpha-thyroid hormone receptor gene (TRalpha or NR1A1) and Rev-erbalpha (NR1D1). In mammals TRalpha pre-mRNAs are alternatively spliced to yield mRNAs encoding functionally antagonistic proteins: TRalpha1, an authentic thyroid hormone receptor; and TRalpha2, a non-hormone-binding variant that acts as a repressor. TRalpha2-specific splicing requires two regulatory elements that overlap with Rev-erbalpha sequences. Functional mapping of these elements reveals minimal splicing enhancer elements that have evolved within the constraints of the overlapping Rev-erbalpha sequence. These results provide insight into the evolution of regulatory elements within the context of bidirectional coding sequences. They also demonstrate the ability of the genetic code to accommodate multiple layers of information within a given sequence, an important property of the code recently suggested on theoretical grounds.
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Affiliation(s)
- Valerie K Salato
- Department of Biological Sciences, Marquette University, Milwaukee, WI, USA
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Dreumont N, Hardy S, Behm-Ansmant I, Kister L, Branlant C, Stévenin J, Bourgeois CF. Antagonistic factors control the unproductive splicing of SC35 terminal intron. Nucleic Acids Res 2009; 38:1353-66. [PMID: 19965769 PMCID: PMC2831310 DOI: 10.1093/nar/gkp1086] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Alternative splicing is regulated in part by variations in the relative concentrations of a variety of factors, including serine/arginine-rich (SR) proteins. The SR protein SC35 self-regulates its expression by stimulating unproductive splicing events in the 3' untranslated region of its own pre-mRNA. Using various minigene constructs containing the terminal retained intron and flanking exons, we identified in the highly conserved last exon a number of exonic splicing enhancer elements responding specifically to SC35, and showed an inverse correlation between affinity of SC35 and enhancer strength. The enhancer region, which is included in a long stem loop, also contains repressor elements, and is recognized by other RNA-binding proteins, notably hnRNP H protein and TAR DNA binding protein (TDP-43). Finally, in vitro and in cellulo experiments indicated that hnRNP H and TDP-43 antagonize the binding of SC35 to the terminal exon and specifically repress the use of SC35 terminal 3' splice site. Our study provides new information about the molecular mechanisms of SC35-mediated splicing activation. It also highlights the existence of a complex network of self- and cross-regulatory mechanisms between splicing regulators, which controls their homeostasis and offers many ways of modulating their concentration in response to the cellular environment.
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Affiliation(s)
- Natacha Dreumont
- IGBMC Department of Functional Genomics, INSERM U964, CNRS UMR 7104, 67400 Illkirch, France
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Sato H, Maquat LE. Remodeling of the pioneer translation initiation complex involves translation and the karyopherin importin beta. Genes Dev 2009; 23:2537-50. [PMID: 19884259 DOI: 10.1101/gad.1817109] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Mammalian mRNAs lose and acquire proteins throughout their life span while undergoing processing, transport, translation, and decay. How translation affects messenger RNA (mRNA)-protein interactions is largely unknown. The pioneer round of translation uses newly synthesized mRNA that is bound by cap-binding protein 80 (CBP80)-CBP20 (also known as the cap-binding complex [CBC]) at the cap, poly(A)-binding protein N1 (PABPN1) and PABPC1 at the poly(A) tail, and, provided biogenesis involves pre-mRNA splicing, exon junction complexes (EJCs) at exon-exon junctions. Subsequent rounds of translation engage mRNA that is bound by eukaryotic translation initiation factor 4E (eIF4E) at the cap and PABPC1 at the poly(A) tail, but that lacks detectable EJCs and PABPN1. Using the level of intracellular iron to regulate the translation of specific mRNAs, we show that translation promotes not only removal of EJC constituents, including the eIF4AIII anchor, but also replacement of PABPN1 by PABPC1. Remarkably, translation does not affect replacement of CBC by eIF4E. Instead, replacement of CBC by eIF4E is promoted by importin beta (IMPbeta): Inhibiting the binding of IMPbeta to the complex of CBC-IMPalpha at an mRNA cap using the IMPalpha IBB (IMPbeta-binding) domain or a RAN variant increases the amount of CBC-bound mRNA and decreases the amount of eIF4E-bound mRNA. Our studies uncover a previously unappreciated role for IMPbeta and a novel paradigm for how newly synthesized messenger ribonucleoproteins (mRNPs) are matured.
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Affiliation(s)
- Hanae Sato
- Department of Biochemistry and Biophysics and Center for RNA Biology, School of Medicine and Dentistry, University of Rochester, Rochester, New York 14642, USA
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Abstract
The SR proteins are not only involved in pre-mRNA splicing but in mRNA export and the initiation of translation. Summary The processing of pre-mRNAs is a fundamental step required for the expression of most metazoan genes. Members of the family of serine/arginine (SR)-rich proteins are critical components of the machineries carrying out these essential processing events, highlighting their importance in maintaining efficient gene expression. SR proteins are characterized by their ability to interact simultaneously with RNA and other protein components via an RNA recognition motif (RRM) and through a domain rich in arginine and serine residues, the RS domain. Their functional roles in gene expression are surprisingly diverse, ranging from their classical involvement in constitutive and alternative pre-mRNA splicing to various post-splicing activities, including mRNA nuclear export, nonsense-mediated decay, and mRNA translation. These activities point up the importance of SR proteins during the regulation of mRNA metabolism.
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Affiliation(s)
- Peter J Shepard
- Department of Microbiology and Molecular Genetics, University of California, Irvine, Irvine, CA 92697-4025, USA
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Vorechovsky I. Transposable elements in disease-associated cryptic exons. Hum Genet 2009; 127:135-54. [PMID: 19823873 DOI: 10.1007/s00439-009-0752-4] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2009] [Accepted: 09/27/2009] [Indexed: 11/28/2022]
Abstract
Transposable elements (TEs) make up a half of the human genome, but the extent of their contribution to cryptic exon activation that results in genetic disease is unknown. Here, a comprehensive survey of 78 mutation-induced cryptic exons previously identified in 51 disease genes revealed the presence of TEs in 40 cases (51%). Most TE-containing exons were derived from short interspersed nuclear elements (SINEs), with Alus and mammalian interspersed repeats (MIRs) covering >18 and >16% of the exonized sequences, respectively. The majority of SINE-derived cryptic exons had splice sites at the same positions of the Alu/MIR consensus as existing SINE exons and their inclusion in the mRNA was facilitated by phylogenetically conserved changes that improved both traditional and auxiliary splicing signals, thus marking intronic TEs amenable for pathogenic exonization. The overrepresentation of MIRs among TE exons is likely to result from their high average exon inclusion levels, which reflect their strong splice sites, a lack of splicing silencers and a high density of enhancers, particularly (G)AA(G) motifs. These elements were markedly depleted in antisense Alu exons, had the most prominent position on the exon-intron gradient scale and are proposed to promote exon definition through enhanced tertiary RNA interactions involving unpaired (di)adenosines. The identification of common mechanisms by which the most dynamic parts of the genome contribute both to new exon creation and genetic disease will facilitate detection of intronic mutations and the development of computational tools that predict TE hot-spots of cryptic exon activation.
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Affiliation(s)
- Igor Vorechovsky
- Division of Human Genetics, University of Southampton School of Medicine, MP808, Tremona Road, Southampton SO16 6YD, UK.
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Akerman M, David-Eden H, Pinter RY, Mandel-Gutfreund Y. A computational approach for genome-wide mapping of splicing factor binding sites. Genome Biol 2009; 10:R30. [PMID: 19296853 PMCID: PMC2691001 DOI: 10.1186/gb-2009-10-3-r30] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2008] [Revised: 02/26/2009] [Accepted: 03/18/2009] [Indexed: 12/18/2022] Open
Abstract
A computational method is presented for genome-wide mapping of splicing factor binding sites that considers both the genomic environment and evolutionary conservation. Alternative splicing is regulated by splicing factors that serve as positive or negative effectors, interacting with regulatory elements along exons and introns. Here we present a novel computational method for genome-wide mapping of splicing factor binding sites that considers both the genomic environment and the evolutionary conservation of the regulatory elements. The method was applied to study the regulation of different alternative splicing events, uncovering an interesting network of interactions among splicing factors.
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Affiliation(s)
- Martin Akerman
- Department of Biology, The Technion, Israel Institute of Technology, Haifa, Israel.
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Abstract
The physiology of microvessels limits the growth and development of tumours. Tumours gain nutrients and excrete waste through growth-associated microvessels. New anticancer therapies target this microvasculature by inhibiting vascular endothelial growth factor A (VEGF-A) splice isoforms that promote microvessel growth. However, certain VEGF-A splice isoforms in normal tissues inhibit growth of microvessels. Thus, it is the VEGF-A isoform balance, which is controlled by mRNA splicing, that orchestrates angiogenesis. Here, we highlight the functional differences between the pro-angiogenic and the anti-angiogenic VEGF-A isoform families and the potential to harness the synthetic capacity of cancer cells to produce factors that inhibit, rather than aid, cancer growth.
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Affiliation(s)
- Steven J Harper
- Microvascular Research Laboratories, Department of Physiology & Pharmacology, Bristol Heart Institute, School of Veterinary Science, University of Bristol, Southwell Street, Bristol BS2 8EJ, UK.
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50
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Moran Y, Weinberger H, Reitzel AM, Sullivan JC, Kahn R, Gordon D, Finnerty JR, Gurevitz M. Intron Retention as a Posttranscriptional Regulatory Mechanism of Neurotoxin Expression at Early Life Stages of the Starlet Anemone Nematostella vectensis. J Mol Biol 2008; 380:437-43. [DOI: 10.1016/j.jmb.2008.05.011] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2008] [Revised: 05/06/2008] [Accepted: 05/07/2008] [Indexed: 01/12/2023]
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