1
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Fronk AD, Manzanares MA, Zheng P, Geier A, Anderson K, Stanton S, Zumrut H, Gera S, Munch R, Frederick V, Dhingra P, Arun G, Akerman M. Development and validation of AI/ML derived splice-switching oligonucleotides. Mol Syst Biol 2024; 20:676-701. [PMID: 38664594 PMCID: PMC11148135 DOI: 10.1038/s44320-024-00034-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2023] [Revised: 04/03/2024] [Accepted: 04/09/2024] [Indexed: 06/05/2024] Open
Abstract
Splice-switching oligonucleotides (SSOs) are antisense compounds that act directly on pre-mRNA to modulate alternative splicing (AS). This study demonstrates the value that artificial intelligence/machine learning (AI/ML) provides for the identification of functional, verifiable, and therapeutic SSOs. We trained XGboost tree models using splicing factor (SF) pre-mRNA binding profiles and spliceosome assembly information to identify modulatory SSO binding sites on pre-mRNA. Using Shapley and out-of-bag analyses we also predicted the identity of specific SFs whose binding to pre-mRNA is blocked by SSOs. This step adds considerable transparency to AI/ML-driven drug discovery and informs biological insights useful in further validation steps. We applied this approach to previously established functional SSOs to retrospectively identify the SFs likely to regulate those events. We then took a prospective validation approach using a novel target in triple negative breast cancer (TNBC), NEDD4L exon 13 (NEDD4Le13). Targeting NEDD4Le13 with an AI/ML-designed SSO decreased the proliferative and migratory behavior of TNBC cells via downregulation of the TGFβ pathway. Overall, this study illustrates the ability of AI/ML to extract actionable insights from RNA-seq data.
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Affiliation(s)
| | | | - Paulina Zheng
- Envisagenics, Inc., Long Island City, NY, 11101, USA
| | - Adam Geier
- Envisagenics, Inc., Long Island City, NY, 11101, USA
| | | | | | - Hasan Zumrut
- Envisagenics, Inc., Long Island City, NY, 11101, USA
| | - Sakshi Gera
- Envisagenics, Inc., Long Island City, NY, 11101, USA
| | - Robin Munch
- Envisagenics, Inc., Long Island City, NY, 11101, USA
| | | | | | - Gayatri Arun
- Envisagenics, Inc., Long Island City, NY, 11101, USA
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2
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Segovia D, Adams DW, Hoffman N, Safaric Tepes P, Wee TL, Cifani P, Joshua-Tor L, Krainer AR. SRSF1 interactome determined by proximity labeling reveals direct interaction with spliceosomal RNA helicase DDX23. Proc Natl Acad Sci U S A 2024; 121:e2322974121. [PMID: 38743621 PMCID: PMC11126954 DOI: 10.1073/pnas.2322974121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2024] [Accepted: 04/15/2024] [Indexed: 05/16/2024] Open
Abstract
SRSF1 is the founding member of the SR protein family. It is required-interchangeably with other SR proteins-for pre-mRNA splicing in vitro, and it regulates various alternative splicing events. Dysregulation of SRSF1 expression contributes to cancer and other pathologies. Here, we characterized SRSF1's interactome using proximity labeling and mass spectrometry. This approach yielded 190 proteins enriched in the SRSF1 samples, independently of the N- or C-terminal location of the biotin-labeling domain. The detected proteins reflect established functions of SRSF1 in pre-mRNA splicing and reveal additional connections to spliceosome proteins, in addition to other recently identified functions. We validated a robust interaction with the spliceosomal RNA helicase DDX23/PRP28 using bimolecular fluorescence complementation and in vitro binding assays. The interaction is mediated by the N-terminal RS-like domain of DDX23 and both RRM1 and the RS domain of SRSF1. During pre-mRNA splicing, DDX23's ATPase activity is essential for the pre-B to B spliceosome complex transition and for release of U1 snRNP from the 5' splice site. We show that the RS-like region of DDX23's N-terminal domain is important for spliceosome incorporation, while larger deletions in this domain alter subnuclear localization. We discuss how the identified interaction of DDX23 with SRSF1 and other SR proteins may be involved in the regulation of these processes.
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Affiliation(s)
- Danilo Segovia
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY11724
- Graduate Program in Molecular and Cellular Biology, Stony Brook University, Stony Brook, NY11794
| | - Dexter W. Adams
- HHMI, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY11724
- W. M. Keck Structural Biology Laboratory, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY11724
- Graduate Program in Genetics, Stony Brook University, Stony Brook, NY11794
| | | | | | - Tse-Luen Wee
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY11724
| | - Paolo Cifani
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY11724
| | - Leemor Joshua-Tor
- HHMI, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY11724
- W. M. Keck Structural Biology Laboratory, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY11724
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3
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Mullari M, Fossat N, Skotte NH, Asenjo-Martinez A, Humphreys DT, Bukh J, Kirkeby A, Scheel TKH, Nielsen ML. Characterising the RNA-binding protein atlas of the mammalian brain uncovers RBM5 misregulation in mouse models of Huntington's disease. Nat Commun 2023; 14:4348. [PMID: 37468457 DOI: 10.1038/s41467-023-39936-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Accepted: 06/30/2023] [Indexed: 07/21/2023] Open
Abstract
RNA-binding proteins (RBPs) are key players regulating RNA processing and are associated with disorders ranging from cancer to neurodegeneration. Here, we present a proteomics workflow for large-scale identification of RBPs and their RNA-binding regions in the mammalian brain identifying 526 RBPs. Analysing brain tissue from males of the Huntington's disease (HD) R6/2 mouse model uncovered differential RNA-binding of the alternative splicing regulator RBM5. Combining several omics workflows, we show that RBM5 binds differentially to transcripts enriched in pathways of neurodegeneration in R6/2 brain tissue. We further find these transcripts to undergo changes in splicing and demonstrate that RBM5 directly regulates these changes in human neurons derived from embryonic stem cells. Finally, we reveal that RBM5 interacts differently with several known huntingtin interactors and components of huntingtin aggregates. Collectively, we demonstrate the applicability of our method for capturing RNA interactor dynamics in the contexts of tissue and disease.
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Affiliation(s)
- Meeli Mullari
- Proteomics Program, Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
| | - Nicolas Fossat
- Copenhagen Hepatitis C Program (CO-HEP), Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- CO-HEP, Department of Infectious Diseases, Copenhagen University Hospital, Hvidovre, Denmark
| | - Niels H Skotte
- Proteomics Program, Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Andrea Asenjo-Martinez
- The Novo Nordisk Foundation Center for Stem Cell Medicine (reNEW) and Department of Neuroscience, University of Copenhagen, Copenhagen, Denmark
| | - David T Humphreys
- Victor Chang Cardiac Research Institute, Darlinghurst, NSW, 2010, Australia
| | - Jens Bukh
- Copenhagen Hepatitis C Program (CO-HEP), Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- CO-HEP, Department of Infectious Diseases, Copenhagen University Hospital, Hvidovre, Denmark
| | - Agnete Kirkeby
- The Novo Nordisk Foundation Center for Stem Cell Medicine (reNEW) and Department of Neuroscience, University of Copenhagen, Copenhagen, Denmark
- Wallenberg Center for Molecular Medicine (WCMM) and Department of Experimental Medical Science, Lund University, Lund, Sweden
| | - Troels K H Scheel
- Copenhagen Hepatitis C Program (CO-HEP), Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- CO-HEP, Department of Infectious Diseases, Copenhagen University Hospital, Hvidovre, Denmark
- Laboratory of Virology and Infectious Disease, The Rockefeller University, New York, NY, USA
| | - Michael L Nielsen
- Proteomics Program, Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
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4
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Mola S, Beauchamp C, Boucher G, Lesage S, Karaky M, Goyette P, Foisy S, Rioux JD. Identifying transcript-level differential expression in primary human immune cells. Mol Immunol 2023; 153:181-193. [PMID: 36527757 DOI: 10.1016/j.molimm.2022.12.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Revised: 11/17/2022] [Accepted: 12/09/2022] [Indexed: 12/23/2022]
Abstract
BACKGROUND Multipotential hematopoietic stem cells differentiate into a wide variety of immune cells with a diversity of functions, including the ability to respond to a variety of stimuli. Importantly, numerous studies have demonstrated the importance of gene transcription in defining cell identity and functions. While these studies have primarily been performed at the level of the gene, it is known that key immune genes such as CD44 and CD45 generate multiple different transcripts that are differentially expressed across different immune cells, and that encode proteins with different sequences and functions. Prior genomic surveys have shown that the mechanisms for generating diversity in expressed transcripts (alternate splicing, alternate transcription start sites, etc.) are very active in immune cells, but have been lacking in terms of identifying genes with multiple transcripts, that are differentially expressed, and likely to affect cell functions. METHODS We first identified the set of genes that had at least two transcripts expressed in our RNA sequencing dataset generated from purified populations of neutrophils, monocytes and five lymphocyte populations (B, NK, γδ T, CD4 + T and CD8 + T) from twelve healthy donors. Next, we developed a heuristic approach to identify genes where two or more transcripts have distinct expression patterns across lymphoid and/or myeloid populations. We then focused our annotation and interpretation on differentially expressed transcripts that affect the coding sequence. This process was repeated to identify transcripts that were differentially expressed between monocytes and populations of macrophages and LPS-stimulated macrophages derived from these monocytes in vitro. RESULTS We found that over 55 % of genes had two or more expressed transcripts, with an average ∼3 transcripts per gene, and that 70 % of these had at least two of the transcripts that encoded proteins with different sequences. As expected, we identified a complex pattern of differential expression for multiple transcripts encoding the CD45 transmembrane protein, but we also found similar evidence for ten other genes (CD300A, FYB1, GPI, LITAF, PSMA1, PTMA, RPL32, SEPTIN9, SH3BP2, SH3KBP1) when comparing the expression patterns of transcripts within myeloid and lymphoid cells. We also identified five genes with differentially expressed transcripts associated with the transition from monocytes to macrophages (FNBP1, KLF6, and SEPTIN9) or between macrophages and LPS-stimulated macrophages (CD44, OAZ2, and SEPTIN9). For the most part, we found that the different transcripts of these genes are expected to impact specific biological functions, for example the different transcripts of SEPTIN9 likely regulate the cytoskeleton in immune cells via their interactions with actins filaments and microtubules. CONCLUSIONS This analytic approach successfully identified multi-transcript genes that are differentially expressed across immune cells and could be applied to other transcriptomic data. DATA AVAILABILITY STATEMENT Researchers can request access to the individual-level data from the current study by contacting the Montreal Heart Institute ethics committee at the following institutional email address: cer.icm@icm-mhi.org.
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Affiliation(s)
- Saraï Mola
- Centre de recherche, Institut de cardiologie de Montréal, 5000 Rue Bélanger, Montréal, Québec H1T 1C8, Canada; Département de biochimie et médecine moléculaire, Université de Montréal, Pavillon Roger-Gaudry, C.P. 6128, Succ. Centre-ville, Montréal, Québec H3C 3J7, Canada.
| | - Claudine Beauchamp
- Centre de recherche, Institut de cardiologie de Montréal, 5000 Rue Bélanger, Montréal, Québec H1T 1C8, Canada.
| | - Gabrielle Boucher
- Centre de recherche, Institut de cardiologie de Montréal, 5000 Rue Bélanger, Montréal, Québec H1T 1C8, Canada.
| | - Sylvie Lesage
- Maisonneuve-Rosemont Hospital Research Center, 5415 boul. De l'Assomption, Montréal, Québec H1T 2M4, Canada; Département de Microbiologie, Infectiologie et Immunologie, Université de Montréal, C.P. 6128, Succ. Centre-ville, Montréal, Québec H3C 3J7, Canada.
| | - Mohamad Karaky
- Centre de recherche, Institut de cardiologie de Montréal, 5000 Rue Bélanger, Montréal, Québec H1T 1C8, Canada.
| | - Philippe Goyette
- Centre de recherche, Institut de cardiologie de Montréal, 5000 Rue Bélanger, Montréal, Québec H1T 1C8, Canada.
| | - Sylvain Foisy
- Centre de recherche, Institut de cardiologie de Montréal, 5000 Rue Bélanger, Montréal, Québec H1T 1C8, Canada.
| | - John D Rioux
- Centre de recherche, Institut de cardiologie de Montréal, 5000 Rue Bélanger, Montréal, Québec H1T 1C8, Canada; Département de biochimie et médecine moléculaire, Université de Montréal, Pavillon Roger-Gaudry, C.P. 6128, Succ. Centre-ville, Montréal, Québec H3C 3J7, Canada; Département de médecine, Université de Montréal, Pavillon Roger-Gaudry, C.P. 6128, Succ. Centre-ville, Montréal, Québec H3C 3J7, Canada.
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5
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Selicky T, Jurcik M, Mikolaskova B, Pitelova A, Mayerova N, Kretova M, Osadska M, Jurcik J, Holic R, Kohutova L, Bellova J, Benko Z, Gregan J, Bagelova Polakova S, Barath P, Cipak L, Cipakova I. Defining the Functional Interactome of Spliceosome-Associated G-Patch Protein Gpl1 in the Fission Yeast Schizosaccharomyces pombe. Int J Mol Sci 2022; 23:12800. [PMID: 36361590 PMCID: PMC9658070 DOI: 10.3390/ijms232112800] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Revised: 10/20/2022] [Accepted: 10/21/2022] [Indexed: 08/31/2023] Open
Abstract
Pre-mRNA splicing plays a fundamental role in securing protein diversity by generating multiple transcript isoforms from a single gene. Recently, it has been shown that specific G-patch domain-containing proteins are critical cofactors involved in the regulation of splicing processes. In this study, using the knock-out strategy, affinity purification and the yeast-two-hybrid assay, we demonstrated that the spliceosome-associated G-patch protein Gpl1 of the fission yeast S. pombe mediates interactions between putative RNA helicase Gih35 (SPAC20H4.09) and WD repeat protein Wdr83, and ensures their binding to the spliceosome. Furthermore, RT-qPCR analysis of the splicing efficiency of deletion mutants indicated that the absence of any of the components of the Gpl1-Gih35-Wdr83 complex leads to defective splicing of fet5 and pwi1, the reference genes whose unspliced isoforms harboring premature stop codons are targeted for degradation by the nonsense-mediated decay (NMD) pathway. Together, our results shed more light on the functional interactome of G-patch protein Gpl1 and revealed that the Gpl1-Gih35-Wdr83 complex plays an important role in the regulation of pre-mRNA splicing in S. pombe.
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Affiliation(s)
- Tomas Selicky
- Department of Genetics, Cancer Research Institute, Biomedical Research Center, Slovak Academy of Sciences, Dubravska cesta 9, 845 05 Bratislava, Slovakia
| | - Matus Jurcik
- Department of Genetics, Cancer Research Institute, Biomedical Research Center, Slovak Academy of Sciences, Dubravska cesta 9, 845 05 Bratislava, Slovakia
| | - Barbora Mikolaskova
- Department of Genetics, Cancer Research Institute, Biomedical Research Center, Slovak Academy of Sciences, Dubravska cesta 9, 845 05 Bratislava, Slovakia
| | - Alexandra Pitelova
- Department of Membrane Biochemistry, Institute of Animal Biochemistry and Genetics, Centre of Biosciences, Slovak Academy of Sciences, Dubravska cesta 9, 840 05 Bratislava, Slovakia
| | - Nina Mayerova
- Department of Genetics, Faculty of Natural Sciences, Comenius University in Bratislava, 841 04 Bratislava, Slovakia
| | - Miroslava Kretova
- Department of Genetics, Cancer Research Institute, Biomedical Research Center, Slovak Academy of Sciences, Dubravska cesta 9, 845 05 Bratislava, Slovakia
| | - Michaela Osadska
- Department of Genetics, Cancer Research Institute, Biomedical Research Center, Slovak Academy of Sciences, Dubravska cesta 9, 845 05 Bratislava, Slovakia
| | - Jan Jurcik
- Department of Genetics, Cancer Research Institute, Biomedical Research Center, Slovak Academy of Sciences, Dubravska cesta 9, 845 05 Bratislava, Slovakia
| | - Roman Holic
- Department of Membrane Biochemistry, Institute of Animal Biochemistry and Genetics, Centre of Biosciences, Slovak Academy of Sciences, Dubravska cesta 9, 840 05 Bratislava, Slovakia
| | - Lenka Kohutova
- Department of Glycobiology, Institute of Chemistry, Slovak Academy of Sciences, Dubravska cesta 9, 845 38 Bratislava, Slovakia
| | - Jana Bellova
- Department of Glycobiology, Institute of Chemistry, Slovak Academy of Sciences, Dubravska cesta 9, 845 38 Bratislava, Slovakia
| | - Zsigmond Benko
- Department of Membrane Biochemistry, Institute of Animal Biochemistry and Genetics, Centre of Biosciences, Slovak Academy of Sciences, Dubravska cesta 9, 840 05 Bratislava, Slovakia
- Department of Molecular Biotechnology and Microbiology, University of Debrecen, Egyetem tér 1, H4032 Debrecen, Hungary
| | - Juraj Gregan
- Department of Applied Genetics and Cell Biology, Institute of Microbial Genetics, University of Natural Resources and Life Sciences, Vienna (BOKU), Konrad Lorenz Strasse 24, 3430 Tulln an der Donau, Austria
| | - Silvia Bagelova Polakova
- Department of Membrane Biochemistry, Institute of Animal Biochemistry and Genetics, Centre of Biosciences, Slovak Academy of Sciences, Dubravska cesta 9, 840 05 Bratislava, Slovakia
| | - Peter Barath
- Department of Glycobiology, Institute of Chemistry, Slovak Academy of Sciences, Dubravska cesta 9, 845 38 Bratislava, Slovakia
- Medirex Group Academy, Novozamocka 67, 949 05 Nitra, Slovakia
| | - Lubos Cipak
- Department of Genetics, Cancer Research Institute, Biomedical Research Center, Slovak Academy of Sciences, Dubravska cesta 9, 845 05 Bratislava, Slovakia
| | - Ingrid Cipakova
- Department of Genetics, Cancer Research Institute, Biomedical Research Center, Slovak Academy of Sciences, Dubravska cesta 9, 845 05 Bratislava, Slovakia
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6
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Saha K, Ghosh G. Cooperative engagement and subsequent selective displacement of SR proteins define the pre-mRNA 3D structural scaffold for early spliceosome assembly. Nucleic Acids Res 2022; 50:8262-8278. [PMID: 35871302 PMCID: PMC9371905 DOI: 10.1093/nar/gkac636] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Revised: 07/04/2022] [Accepted: 07/13/2022] [Indexed: 11/13/2022] Open
Abstract
Abstract
We recently reported that serine–arginine-rich (SR) protein-mediated pre-mRNA structural remodeling generates a pre-mRNA 3D structural scaffold that is stably recognized by the early spliceosomal components. However, the intermediate steps between the free pre-mRNA and the assembled early spliceosome are not yet characterized. By probing the early spliceosomal complexes in vitro and RNA-protein interactions in vivo, we show that the SR proteins bind the pre-mRNAs cooperatively generating a substrate that recruits U1 snRNP and U2AF65 in a splice signal-independent manner. Excess U1 snRNP selectively displaces some of the SR protein molecules from the pre-mRNA generating the substrate for splice signal-specific, sequential recognition by U1 snRNP, U2AF65 and U2AF35. Our work thus identifies a novel function of U1 snRNP in mammalian splicing substrate definition, explains the need for excess U1 snRNP compared to other U snRNPs in vivo, demonstrates how excess SR proteins could inhibit splicing, and provides a conceptual basis to examine if this mechanism of splicing substrate definition is employed by other splicing regulatory proteins.
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Affiliation(s)
- Kaushik Saha
- Department of Chemistry and Biochemistry, University of California San Diego , 9500 Gilman Drive , La Jolla , CA 92093-0375, USA
| | - Gourisankar Ghosh
- Department of Chemistry and Biochemistry, University of California San Diego , 9500 Gilman Drive , La Jolla , CA 92093-0375, USA
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7
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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: 19] [Impact Index Per Article: 9.5] [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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8
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Shefer K, Boulos A, Gotea V, Arafat M, Ben Chaim Y, Muharram A, Isaac S, Eden A, Sperling J, Elnitski L, Sperling R. A novel role for nucleolin in splice site selection. RNA Biol 2021; 19:333-352. [PMID: 35220879 PMCID: PMC8890436 DOI: 10.1080/15476286.2021.2020455] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Accepted: 12/10/2021] [Indexed: 01/12/2023] Open
Abstract
Latent 5' splice sites, not normally used, are highly abundant in human introns, but are activated under stress and in cancer, generating thousands of nonsense mRNAs. A previously proposed mechanism to suppress latent splicing was shown to be independent of NMD, with a pivotal role for initiator-tRNA independent of protein translation. To further elucidate this mechanism, we searched for nuclear proteins directly bound to initiator-tRNA. Starting with UV-crosslinking, we identified nucleolin (NCL) interacting directly and specifically with initiator-tRNA in the nucleus, but not in the cytoplasm. Next, we show the association of ini-tRNA and NCL with pre-mRNA. We further show that recovery of suppression of latent splicing by initiator-tRNA complementation is NCL dependent. Finally, upon nucleolin knockdown we show activation of latent splicing in hundreds of coding transcripts having important cellular functions. We thus propose nucleolin, a component of the endogenous spliceosome, through its direct binding to initiator-tRNA and its effect on latent splicing, as the first protein of a nuclear quality control mechanism regulating splice site selection to protect cells from latent splicing that can generate defective mRNAs.
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Affiliation(s)
- Kinneret Shefer
- Department of Genetics, The Hebrew University of Jerusalem, JerusalemIsrael
| | - Ayub Boulos
- Department of Genetics, The Hebrew University of Jerusalem, JerusalemIsrael
| | - Valer Gotea
- Translational and Functional Genomics Branch, National Human Genome Research Institute, NIH, Bethesda, MDUSA
| | - Maram Arafat
- Department of Genetics, The Hebrew University of Jerusalem, JerusalemIsrael
| | - Yair Ben Chaim
- Department of Natural Sciences, The Open University, RaananaIsrael
| | - Aya Muharram
- Department of Genetics, The Hebrew University of Jerusalem, JerusalemIsrael
| | - Sara Isaac
- Department of Cell and Developmental Biology, The Hebrew University of Jerusalem, JerusalemIsrael
| | - Amir Eden
- Department of Cell and Developmental Biology, The Hebrew University of Jerusalem, JerusalemIsrael
| | - Joseph Sperling
- Department of Organic Chemistry, The Weizmann Institute of Science, RehovotIsrael
| | - Laura Elnitski
- Translational and Functional Genomics Branch, National Human Genome Research Institute, NIH, Bethesda, MDUSA
| | - Ruth Sperling
- Department of Genetics, The Hebrew University of Jerusalem, JerusalemIsrael
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9
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Alternative splicing of mRNA in colorectal cancer: new strategies for tumor diagnosis and treatment. Cell Death Dis 2021; 12:752. [PMID: 34330892 PMCID: PMC8324868 DOI: 10.1038/s41419-021-04031-w] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 07/12/2021] [Accepted: 07/12/2021] [Indexed: 02/07/2023]
Abstract
Alternative splicing (AS) is an important event that contributes to posttranscriptional gene regulation. This process leads to several mature transcript variants with diverse physiological functions. Indeed, disruption of various aspects of this multistep process, such as cis- or trans- factor alteration, promotes the progression of colorectal cancer. Therefore, targeting some specific processes of AS may be an effective therapeutic strategy for treating cancer. Here, we provide an overview of the AS events related to colorectal cancer based on research done in the past 5 years. We focus on the mechanisms and functions of variant products of AS that are relevant to malignant hallmarks, with an emphasis on variants with clinical significance. In addition, novel strategies for exploiting the therapeutic value of AS events are discussed.
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10
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Lai J, Yang H, Xu T. Systemic characterization of alternative splicing related to prognosis and immune infiltration in malignant mesothelioma. BMC Cancer 2021; 21:848. [PMID: 34294080 PMCID: PMC8299698 DOI: 10.1186/s12885-021-08548-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2021] [Accepted: 07/07/2021] [Indexed: 01/19/2023] Open
Abstract
BACKGROUND Malignant mesothelioma (MM) is a relatively rare and highly lethal tumor with few treatment options. Thus, it is important to identify prognostic markers that can help clinicians diagnose mesothelioma earlier and assess disease activity more accurately. Alternative splicing (AS) events have been recognized as critical signatures for tumor diagnosis and treatment in multiple cancers, including MM. METHODS We systematically examined the AS events and clinical information of 83 MM samples from TCGA database. Univariate Cox regression analysis was used to identify AS events associated with overall survival. LASSO analyses followed by multivariate Cox regression analyses were conducted to construct the prognostic signatures and assess the accuracy of these prognostic signatures by receiver operating characteristic (ROC) curve and Kaplan-Meier survival analyses. The ImmuCellAI and ssGSEA algorithms were used to assess the degrees of immune cell infiltration in MM samples. The survival-related splicing regulatory network was established based on the correlation between survival-related AS events and splicing factors (SFs). RESULTS A total of 3976 AS events associated with overall survival were identified by univariate Cox regression analysis, and ES events accounted for the greatest proportion. We constructed prognostic signatures based on survival-related AS events. The prognostic signatures proved to be an efficient predictor with an area under the curve (AUC) greater than 0.9. Additionally, the risk score based on 6 key AS events proved to be an independent prognostic factor, and a nomogram composed of 6 key AS events was established. We found that the risk score was significantly decreased in patients with the epithelioid subtype. In addition, unsupervised clustering clearly showed that the risk score was associated with immune cell infiltration. The abundances of cytotoxic T (Tc) cells, natural killer (NK) cells and T-helper 17 (Th17) cells were higher in the high-risk group, whereas the abundances of induced regulatory T (iTreg) cells were lower in the high-risk group. Finally, we identified 3 SFs (HSPB1, INTS1 and LUC7L2) that were significantly associated with MM patient survival and then constructed a regulatory network between the 3 SFs and survival-related AS to reveal potential regulatory mechanisms in MM. CONCLUSION Our study provided a prognostic signature based on 6 key events, representing a better effective tumor-specific diagnostic and prognostic marker than the TNM staging system. AS events that are correlated with the immune system may be potential therapeutic targets for MM.
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Affiliation(s)
- Jinzhi Lai
- Department of Oncology, The Second Affiliated Hospital of Fujian Medical University, Quanzhou, 362000, Fujian, China
| | - Hainan Yang
- Department of Ultrasound, The Second Affiliated Hospital of Fujian Medical University, Quanzhou, Fujian, China
| | - Tianwen Xu
- Department of Oncology, The Second Affiliated Hospital of Fujian Medical University, Quanzhou, 362000, Fujian, China.
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11
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Daniels NJ, Hershberger CE, Gu X, Schueger C, DiPasquale WM, Brick J, Saunthararajah Y, Maciejewski JP, Padgett RA. Functional analyses of human LUC7-like proteins involved in splicing regulation and myeloid neoplasms. Cell Rep 2021; 35:108989. [PMID: 33852859 PMCID: PMC8078730 DOI: 10.1016/j.celrep.2021.108989] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Revised: 02/12/2021] [Accepted: 03/23/2021] [Indexed: 02/06/2023] Open
Abstract
Vertebrates have evolved three paralogs, termed LUC7L, LUC7L2, and LUC7L3, of the essential yeast U1 small nuclear RNA (snRNA)-associated splicing factor Luc7p. We investigated the mechanistic and regulatory functions of these putative splicing factors, of which one (LUC7L2) is mutated or deleted in myeloid neoplasms. Protein interaction data show that all three proteins bind similar core but distinct regulatory splicing factors, probably mediated through their divergent arginine-serine-rich domains, which are not present in Luc7p. Knockdown of each factor reveals mostly unique sets of significantly dysregulated alternative splicing events dependent on their binding locations, which are largely non-overlapping. Notably, knockdown of LUC7L2 alone significantly upregulates the expression of multiple spliceosomal factors and downregulates glycolysis genes, possibly contributing to disease pathogenesis. RNA binding studies reveal that LUC7L2 and LUC7L3 crosslink to weak 5' splice sites and to the 5' end of U1 snRNA, establishing an evolutionarily conserved role in 5' splice site selection.
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Affiliation(s)
- Noah J Daniels
- Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine, School of Medicine, Case Western Reserve University, Cleveland, OH, USA; Department of Cardiovascular and Metabolic Sciences, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA
| | - Courtney E Hershberger
- Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine, School of Medicine, Case Western Reserve University, Cleveland, OH, USA; Department of Cardiovascular and Metabolic Sciences, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA
| | - Xiaorong Gu
- Department of Translational Hematology and Oncology Research, Taussig Cancer Institute, Cleveland Clinic, Cleveland, OH, USA
| | - Caroline Schueger
- Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine, School of Medicine, Case Western Reserve University, Cleveland, OH, USA; Department of Translational Hematology and Oncology Research, Taussig Cancer Institute, Cleveland Clinic, Cleveland, OH, USA
| | - William M DiPasquale
- Department of Cardiovascular and Metabolic Sciences, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA
| | - Jonathan Brick
- Department of Cardiovascular and Metabolic Sciences, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA
| | - Yogen Saunthararajah
- Department of Translational Hematology and Oncology Research, Taussig Cancer Institute, Cleveland Clinic, Cleveland, OH, USA
| | - Jaroslaw P Maciejewski
- Department of Translational Hematology and Oncology Research, Taussig Cancer Institute, Cleveland Clinic, Cleveland, OH, USA
| | - Richard A Padgett
- Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine, School of Medicine, Case Western Reserve University, Cleveland, OH, USA; Department of Cardiovascular and Metabolic Sciences, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA.
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12
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Sun G, Zhou H, Chen K, Zeng J, Zhang Y, Yan L, Yao W, Hu J, Wang T, Xing J, Xiao K, Wu L, Ye Z, Xu H. HnRNP A1 - mediated alternative splicing of CCDC50 contributes to cancer progression of clear cell renal cell carcinoma via ZNF395. JOURNAL OF EXPERIMENTAL & CLINICAL CANCER RESEARCH : CR 2020; 39:116. [PMID: 32560659 PMCID: PMC7304168 DOI: 10.1186/s13046-020-01606-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Accepted: 05/28/2020] [Indexed: 01/26/2023]
Abstract
BACKGROUND Aberrant alternative splicing events play critical roles in carcinogenesis and progression of many cancers, while sparse studies regarding to alternative splicing are available for clear cell renal cell carcinoma (ccRCC). We identified that alternative splicing of coiled-coil domain containing 50 (CCDC50) was dysregulated in ccRCC, whereas the clinical significance of this splicing event and its splicing regulation mechanisms were still elusive. METHODS Bioinformatic algorithm was utilized to identify significant exon skipping events in ccRCC via exon sequencing data from The Cancer Genome Atlas. Semi-quantitative real-time polymerase chain reaction and western blot were used to validate the aberrant expression of different transcripts in renal cancer tissues, cell lines and corresponding noncancerous controls. Short hairpin RNA targeting CCDC50 and overexpressing plasmids for each transcript were introduced into ccRCC cell lines, followed by a series of in vitro and in vivo functional experiments. Moreover, a panel of splicing factors were identified and their roles on splicing regulation of CCDC50 precursor mRNA (pre-mRNA) were studied. Furthermore, RNAseq data were analyzed to elucidate downstream molecules of CCDC50. Two-way analysis of variance and unpaired Student t test were used in statistical analysis. RESULTS Pre-mRNA of CCDC50 generated two transcripts, full-length transcript (CCDC50-FL) and truncated transcript (CCDC50-S) with exon 6 skipped. CCDC50-S was overexpressed in ccRCC tissues and cell lines compared to noncancerous counterparts, but CCDC50-FL was only detected in noncancerous tissues and normal renal epithelial cells. Higher percent spliced-in index was associated with better survival in ccRCC patients. In vitro and in vivo functional experiments indicated that CCDC50-S transcript promoted the proliferation, migration, invasion and tumorigenesis of ccRCC, while CCDC50-FL exerted opposite tumor suppressive functions. Besides, we identified that heterogeneous nuclear ribonucleoprotein A1 (HnRNP A1) could promote the skipping of exon 6, which resulted in higher portion of CCDC50-S and oncogenic transformation. Moreover, zinc finger protein 395 (ZNF395) was identified as a downstream protein of CCDC50-S, and the interaction initiated oncogenic pathways which were involved in ccRCC progression. CONCLUSIONS Aberrant alternative splicing of CCDC50 is regulated by HnRNP A1 in ccRCC. This splicing event contributes to cancer progression through the downstream pathway involving ZNF395.
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Affiliation(s)
- Guoliang Sun
- grid.33199.310000 0004 0368 7223Department of Urology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030 P.R. China ,Hubei Institute of Urology, Wuhan, 430030 P.R. China
| | - Hui Zhou
- grid.33199.310000 0004 0368 7223Department of Urology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030 P.R. China ,Hubei Institute of Urology, Wuhan, 430030 P.R. China
| | - Ke Chen
- grid.33199.310000 0004 0368 7223Department of Urology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030 P.R. China ,Hubei Institute of Urology, Wuhan, 430030 P.R. China
| | - Jin Zeng
- grid.33199.310000 0004 0368 7223Department of Urology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030 P.R. China ,Hubei Institute of Urology, Wuhan, 430030 P.R. China
| | - Yangjun Zhang
- grid.33199.310000 0004 0368 7223Department of Urology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030 P.R. China ,Hubei Institute of Urology, Wuhan, 430030 P.R. China
| | - Libin Yan
- grid.33199.310000 0004 0368 7223Department of Urology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030 P.R. China ,Hubei Institute of Urology, Wuhan, 430030 P.R. China
| | - Weimin Yao
- grid.33199.310000 0004 0368 7223Department of Urology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030 P.R. China ,Hubei Institute of Urology, Wuhan, 430030 P.R. China
| | - Junhui Hu
- Hubei Institute of Urology, Wuhan, 430030 P.R. China ,grid.19006.3e0000 0000 9632 6718Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, CA 90095 USA
| | - Tao Wang
- grid.412625.6Department of Urology, The First Affiliated Hospital of Xiamen University, Xiamen, 361000 P.R. China
| | - Jinchun Xing
- grid.412625.6Department of Urology, The First Affiliated Hospital of Xiamen University, Xiamen, 361000 P.R. China
| | - Kefeng Xiao
- Department of Urology, The People’s Hospital of Shenzhen City, Shenzhen, 518000 P.R. China
| | - Lily Wu
- grid.19006.3e0000 0000 9632 6718Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, CA 90095 USA
| | - Zhangqun Ye
- grid.33199.310000 0004 0368 7223Department of Urology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030 P.R. China ,Hubei Institute of Urology, Wuhan, 430030 P.R. China
| | - Hua Xu
- Department of Urology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, P.R. China. .,Hubei Institute of Urology, Wuhan, 430030, P.R. China.
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Sebbag-Sznajder N, Brody Y, Hochberg-Laufer H, Shav-Tal Y, Sperling J, Sperling R. Dynamic Supraspliceosomes Are Assembled on Different Transcripts Regardless of Their Intron Number and Splicing State. Front Genet 2020; 11:409. [PMID: 32499811 PMCID: PMC7243799 DOI: 10.3389/fgene.2020.00409] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Accepted: 03/31/2020] [Indexed: 11/13/2022] Open
Abstract
Splicing and alternative splicing of pre-mRNA are key sources in the formation of diversity in the human proteome. These processes have a central role in the regulation of the gene expression pathway. Yet, how spliceosomes are assembled on a multi-intronic pre-mRNA is at present not well understood. To study the spliceosomes assembled in vivo on transcripts with variable number of introns, we examined a series of three related transcripts derived from the β-globin gene, where two transcript types contained increasing number of introns, while one had only an exon. Each transcript had multiple MS2 sequence repeats that can be bound by the MS2 coat protein. Using our protocol for isolation of endogenous spliceosomes under native conditions from cell nuclei, we show that all three transcripts are found in supraspliceosomes – 21 MDa dynamic complexes, sedimenting at 200S in glycerol gradients, and composed of four native spliceosomes connected by the transcript. Affinity purification of complexes assembled on the transcript with most introns (termed E6), using the MS2 tag, confirmed the assembly of E6 in supraspliceosomes with components such as Sm proteins and PSF. Furthermore, splicing inhibition by spliceostatin A did not inhibit the assembly of supraspliceosomes on the E6 transcript, yet increased the percentage of E6 pre-mRNA supraspliceosomes. These findings were corroborated in intact cells, using RNA FISH to detect the MS2-tagged E6 mRNA, together with GFP-tagged splicing factors, showing the assembly of splicing factors SRSF2, U1-70K, and PRP8 onto the E6 transcripts under normal conditions and also when splicing was inhibited. This study shows that different transcripts with different number of introns, or lacking an intron, are assembled in supraspliceosomes even when splicing is inhibited. This assembly starts at the site of transcription and can continue during the life of the transcript in the nucleoplasm. This study further confirms the dynamic and universal nature of supraspliceosomes that package RNA polymerase II transcribed pre-mRNAs into complexes composed of four native spliceosomes connected by the transcript, independent of their length, number of introns, or splicing state.
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Affiliation(s)
| | - Yehuda Brody
- The Mina and Everard Goodman Faculty of Life Sciences and The Institute of Nanotechnology and Advanced Materials, Bar Ilan University, Ramat Gan, Israel
| | - Hodaya Hochberg-Laufer
- The Mina and Everard Goodman Faculty of Life Sciences and The Institute of Nanotechnology and Advanced Materials, Bar Ilan University, Ramat Gan, Israel
| | - Yaron Shav-Tal
- The Mina and Everard Goodman Faculty of Life Sciences and The Institute of Nanotechnology and Advanced Materials, Bar Ilan University, Ramat Gan, Israel
| | - Joseph Sperling
- Department of Organic Chemistry, The Weizmann Institute of Science, Rehovot, Israel
| | - Ruth Sperling
- Department of Genetics, The Hebrew University of Jerusalem, Jerusalem, Israel
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14
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Abstract
Studies on myotonic dystrophy type 1 (DM1) have led to the RNA-mediated disease model for hereditary disorders caused by noncoding microsatellite expansions. This model proposes that DM1 disease manifestations are caused by a reversion to fetal RNA processing patterns in adult tissues due to the expression of toxic CUG RNA expansions (CUGexp) leading to decreased muscleblind-like, but increased CUGBP1/ETR3-like factor 1 (CELF1), alternative splicing activities. Here, we test this model in vivo, using the mouse HSA LR poly(CUG) model for DM1 and recombinant adeno-associated virus (rAAV)-mediated transduction of specific splicing factors. Surprisingly, systemic overexpression of HNRNPA1, not previously linked to DM1, also shifted DM1-relevant splicing targets to fetal isoforms, resulting in more severe muscle weakness/myopathy as early as 4 to 6 wk posttransduction, whereas rAAV controls were unaffected. Overexpression of HNRNPA1 promotes fetal exon inclusion of representative DM1-relevant splicing targets in differentiated myoblasts, and HITS-CLIP of rAAV-mycHnrnpa1-injected muscle revealed direct interactions of HNRNPA1 with these targets in vivo. Similar to CELF1, HNRNPA1 protein levels decrease during postnatal development, but are elevated in both regenerating mouse muscle and DM1 skeletal muscle. Our studies suggest that CUGexp RNA triggers abnormal expression of multiple nuclear RNA binding proteins, including CELF1 and HNRNPA1, that antagonize MBNL activity to promote fetal splicing patterns.
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15
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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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16
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SRSF1 and PTBP1 Are trans-Acting Factors That Suppress the Formation of a CD33 Splicing Isoform Linked to Alzheimer's Disease Risk. Mol Cell Biol 2019; 39:MCB.00568-18. [PMID: 31208978 PMCID: PMC6712934 DOI: 10.1128/mcb.00568-18] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2018] [Accepted: 06/08/2019] [Indexed: 12/19/2022] Open
Abstract
A single nucleotide polymorphism (SNP) in exon 2 of the CD33 gene is associated with reduced susceptibility to late-onset Alzheimer’s disease (AD) and causal for elevated mRNA lacking exon 2. In contrast to full-length CD33, transcripts lacking exon 2 result in CD33 protein unable to suppress activation responses in myeloid cells, including microglia. Currently, little is known about the regulation of CD33 exon 2 splicing. A single nucleotide polymorphism (SNP) in exon 2 of the CD33 gene is associated with reduced susceptibility to late-onset Alzheimer’s disease (AD) and causal for elevated mRNA lacking exon 2. In contrast to full-length CD33, transcripts lacking exon 2 result in CD33 protein unable to suppress activation responses in myeloid cells, including microglia. Currently, little is known about the regulation of CD33 exon 2 splicing. Using functional genomics and proteomic approaches, we found that SRSF1 and PTBP1 act as splicing enhancers to increase CD33 exon 2 inclusion in mRNA. Binding of PTBP1 to RNA sequences proximal to the intron 1-exon 2 splice junction is altered by the SNP and represents a potential mechanism behind the SNP-genotype dependent alternative splicing. Our studies also reveal that binding of SRSF1 to the CD33 RNA is not altered by the SNP genotype. Instead, a putative SRSF1 binding sequence at the 3′ end of exon 2 directs CD33 exon 2 inclusion into the mRNA, indicating that PTBP1 and SRSF1 promote full-length isoform expression through different mechanisms. Our findings shed light on molecular interactions that regulate CD33 exon 2 splicing, ultimately impacting receptor expression on the cell surface. These data aid in the understanding of CD33’s regulation of microglial signaling underpinning the AD genetic associations.
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17
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Sperling R. Small non-coding RNA within the endogenous spliceosome and alternative splicing regulation. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2019; 1862:194406. [PMID: 31323432 DOI: 10.1016/j.bbagrm.2019.07.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Revised: 07/08/2019] [Accepted: 07/09/2019] [Indexed: 10/26/2022]
Abstract
Splicing and alternative splicing (AS), which occur in the endogenous spliceosome, play major roles in regulating gene expression, and defects in them are involved in numerous human diseases including cancer. Although the mechanism of the splicing reaction is well understood, the regulation of AS remains to be elucidated. A group of essential regulatory factors in gene expression are small non-coding RNAs (sncRNA): e.g. microRNA, mainly known for their inhibitory role in translation in the cytoplasm; and small nucleolar RNA, known for their role in methylating non-coding RNA in the nucleolus. Here I highlight a new aspect of sncRNAs found within the endogenous spliceosome. Assembled in non-canonical complexes and through different base pairing than their canonical ones, spliceosomal sncRNAs can potentially target different RNAs. Examples of spliceosomal sncRNAs regulating AS, regulating gene expression, and acting in a quality control of AS are reviewed, suggesting novel functions for spliceosomal sncRNAs. This article is part of a Special Issue entitled: RNA structure and splicing regulation edited by Francisco Baralle, Ravindra Singh and Stefan Stamm.
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Affiliation(s)
- Ruth Sperling
- Department of Genetics, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.
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18
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Caudron-Herger M, Rusin SF, Adamo ME, Seiler J, Schmid VK, Barreau E, Kettenbach AN, Diederichs S. R-DeeP: Proteome-wide and Quantitative Identification of RNA-Dependent Proteins by Density Gradient Ultracentrifugation. Mol Cell 2019; 75:184-199.e10. [PMID: 31076284 DOI: 10.1016/j.molcel.2019.04.018] [Citation(s) in RCA: 66] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Revised: 01/07/2019] [Accepted: 04/11/2019] [Indexed: 12/16/2022]
Abstract
The comprehensive but specific identification of RNA-binding proteins as well as the discovery of RNA-associated protein functions remain major challenges in RNA biology. Here we adapt the concept of RNA dependence, defining a protein as RNA dependent when its interactome depends on RNA. We converted this concept into a proteome-wide, unbiased, and enrichment-free screen called R-DeeP (RNA-dependent proteins), based on density gradient ultracentrifugation. Quantitative mass spectrometry identified 1,784 RNA-dependent proteins, including 537 lacking known links to RNA. Exploiting the quantitative nature of R-DeeP, proteins were classified as not, partially, or completely RNA dependent. R-DeeP identified the transcription factor CTCF as completely RNA dependent, and we uncovered that RNA is required for the CTCF-chromatin association. Additionally, R-DeeP allows reconstruction of protein complexes based on co-segregation. The whole dataset is available at http://R-DeeP.dkfz.de, providing proteome-wide, specific, and quantitative identification of proteins with RNA-dependent interactions and aiming at future functional discovery of RNA-protein complexes.
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Affiliation(s)
- Maiwen Caudron-Herger
- Division of RNA Biology and Cancer, German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany.
| | - Scott F Rusin
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth, Hanover, NH 03755, USA
| | - Mark E Adamo
- Norris Cotton Cancer Center, Geisel School of Medicine at Dartmouth, Lebanon, NH 03756, USA
| | - Jeanette Seiler
- Division of RNA Biology and Cancer, German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany
| | - Vera K Schmid
- Division of RNA Biology and Cancer, German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany
| | - Elsa Barreau
- Division of RNA Biology and Cancer, German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany
| | - Arminja N Kettenbach
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth, Hanover, NH 03755, USA; Norris Cotton Cancer Center, Geisel School of Medicine at Dartmouth, Lebanon, NH 03756, USA
| | - Sven Diederichs
- Division of RNA Biology and Cancer, German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany; Division of Cancer Research, Department of Thoracic Surgery, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, German Cancer Consortium (DKTK)- Partner Site Freiburg, 79106 Freiburg, Germany; National Center for Tumor Diseases (NCT), Partner Site Heidelberg, Heidelberg, Germany.
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19
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Denichenko P, Mogilevsky M, Cléry A, Welte T, Biran J, Shimshon O, Barnabas GD, Danan-Gotthold M, Kumar S, Yavin E, Levanon EY, Allain FH, Geiger T, Levkowitz G, Karni R. Specific inhibition of splicing factor activity by decoy RNA oligonucleotides. Nat Commun 2019; 10:1590. [PMID: 30962446 PMCID: PMC6453957 DOI: 10.1038/s41467-019-09523-0] [Citation(s) in RCA: 60] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Accepted: 03/12/2019] [Indexed: 12/31/2022] Open
Abstract
Alternative splicing, a fundamental step in gene expression, is deregulated in many diseases. Splicing factors (SFs), which regulate this process, are up- or down regulated or mutated in several diseases including cancer. To date, there are no inhibitors that directly inhibit the activity of SFs. We designed decoy oligonucleotides, composed of several repeats of a RNA motif, which is recognized by a single SF. Here we show that decoy oligonucleotides targeting splicing factors RBFOX1/2, SRSF1 and PTBP1, can specifically bind to their respective SFs and inhibit their splicing and biological activities both in vitro and in vivo. These decoy oligonucleotides present an approach to specifically downregulate SF activity in conditions where SFs are either up-regulated or hyperactive. Alternative splicing, critical for gene expression, is deregulated in many diseases. Here the authors develop decoy oligonucleotides to specifically downregulate splicing factors activity.
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Affiliation(s)
- Polina Denichenko
- Department of Biochemistry and Molecular Biology, Institute for Medical Research Israel-Canada, Hebrew University-Hadassah Medical School, Jerusalem, 9112001, Israel
| | - Maxim Mogilevsky
- Department of Biochemistry and Molecular Biology, Institute for Medical Research Israel-Canada, Hebrew University-Hadassah Medical School, Jerusalem, 9112001, Israel
| | - Antoine Cléry
- Institute of Molecular Biology and Biophysics, ETH Zurich, Hönggerbergring 64, 8093, Zurich, Switzerland
| | - Thomas Welte
- Dynamic Biosensors, GmbH, Lochhamer Strasse 15, 82152, Martinsried/Planegg, Germany
| | - Jakob Biran
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, 76100, Israel
| | - Odelia Shimshon
- Department of Medicinal Chemistry, Institute for Drug Research, Hebrew University-Hadassah Medical School, Jerusalem, 9112001, Israel
| | - Georgina D Barnabas
- Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, 6997801, Israel
| | - Miri Danan-Gotthold
- Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, 52900, Israel
| | - Saran Kumar
- Department of Developmental Biology and Cancer Research, Institute for Medical Research Israel-Canada, Faculty of Medicine, Hebrew University-Hadassah Medical School, Jerusalem, 9112001, Israel
| | - Eylon Yavin
- Department of Medicinal Chemistry, Institute for Drug Research, Hebrew University-Hadassah Medical School, Jerusalem, 9112001, Israel
| | - Erez Y Levanon
- Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, 52900, Israel
| | - Frédéric H Allain
- Institute of Molecular Biology and Biophysics, ETH Zurich, Hönggerbergring 64, 8093, Zurich, Switzerland
| | - Tamar Geiger
- Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, 6997801, Israel
| | - Gil Levkowitz
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, 76100, Israel
| | - Rotem Karni
- Department of Biochemistry and Molecular Biology, Institute for Medical Research Israel-Canada, Hebrew University-Hadassah Medical School, Jerusalem, 9112001, Israel.
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Ashraf U, Benoit-Pilven C, Lacroix V, Navratil V, Naffakh N. Advances in Analyzing Virus-Induced Alterations of Host Cell Splicing. Trends Microbiol 2018; 27:268-281. [PMID: 30577974 DOI: 10.1016/j.tim.2018.11.004] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Revised: 10/19/2018] [Accepted: 11/09/2018] [Indexed: 12/14/2022]
Abstract
Alteration of host cell splicing is a common feature of many viral infections which is underappreciated because of the complexity and technical difficulty of studying alternative splicing (AS) regulation. Recent advances in RNA sequencing technologies revealed that up to several hundreds of host genes can show altered mRNA splicing upon viral infection. The observed changes in AS events can be either a direct consequence of viral manipulation of the host splicing machinery or result indirectly from the virus-induced innate immune response or cellular damage. Analysis at a higher resolution with single-cell RNAseq, and at a higher scale with the integration of multiple omics data sets in a systems biology perspective, will be needed to further comprehend this complex facet of virus-host interactions.
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Affiliation(s)
- Usama Ashraf
- Institut Pasteur, Unité de Génétique Moléculaire des Virus à ARN, Département de Virologie, F-75015 Paris, France; CNRS UMR3569, F-75015 Paris, France; Université Paris Diderot, Sorbonne Paris Cité EA302, F-75015 Paris, France
| | - Clara Benoit-Pilven
- INSERM U1028; CNRS UMR5292, Lyon Neuroscience Research Center, Genetic of Neuro-development Anomalies Team, F-69000 Lyon, France; Université Claude Bernard Lyon 1, CNRS UMR5558, Laboratoire de Biométrie et Biologie Evolutive, F-69622 Villeurbanne, France; EPI ERABLE, INRIA Grenoble Rhône-Alpes, F-38330 Montbonnot Saint-Martin, France
| | - Vincent Lacroix
- Université Claude Bernard Lyon 1, CNRS UMR5558, Laboratoire de Biométrie et Biologie Evolutive, F-69622 Villeurbanne, France; EPI ERABLE, INRIA Grenoble Rhône-Alpes, F-38330 Montbonnot Saint-Martin, France
| | - Vincent Navratil
- PRABI, Rhône Alpes Bioinformatics Center, UCBL, Université Claude Bernard Lyon 1, F-69000 Lyon, France; European Virus Bioinformatics Center, Leutragraben 1, D-07743 Jena, Germany
| | - Nadia Naffakh
- Institut Pasteur, Unité de Génétique Moléculaire des Virus à ARN, Département de Virologie, F-75015 Paris, France; CNRS UMR3569, F-75015 Paris, France; Université Paris Diderot, Sorbonne Paris Cité EA302, F-75015 Paris, France.
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21
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El Marabti E, Younis I. The Cancer Spliceome: Reprograming of Alternative Splicing in Cancer. Front Mol Biosci 2018; 5:80. [PMID: 30246013 PMCID: PMC6137424 DOI: 10.3389/fmolb.2018.00080] [Citation(s) in RCA: 152] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Accepted: 08/09/2018] [Indexed: 12/15/2022] Open
Abstract
Alternative splicing allows for the expression of multiple RNA and protein isoforms from one gene, making it a major contributor to transcriptome and proteome diversification in eukaryotes. Advances in next generation sequencing technologies and genome-wide analyses have recently underscored the fact that the vast majority of multi-exon genes under normal physiology engage in alternative splicing in tissue-specific and developmental-specific manner. On the other hand, cancer cells exhibit remarkable transcriptome alterations partly by adopting cancer-specific splicing isoforms. These isoforms and their encoded proteins are not insignificant byproducts of the abnormal physiology of cancer cells, but either drivers of cancer progression or small but significant contributors to specific cancer hallmarks. Thus, it is paramount that the pathways that regulate alternative splicing in cancer, including the splicing factors that bind to pre-mRNAs and modulate spliceosome recruitment. In this review, we present a few distinct cases of alternative splicing in cancer, with an emphasis on their regulation as well as their contribution to cancer cell phenotype. Several categories of splicing aberrations are highlighted, including alterations in cancer-related genes that directly affect their pre-mRNA splicing, mutations in genes encoding splicing factors or core spliceosomal subunits, and the seemingly mutation-free disruptions in the balance of the expression of RNA-binding proteins, including components of both the major (U2-dependent) and minor (U12-dependent) spliceosomes. Given that the latter two classes cause global alterations in splicing that affect a wide range of genes, it remains a challenge to identify the ones that contribute to cancer progression. These challenges necessitate a systematic approach to decipher these aberrations and their impact on cancer. Ultimately, a sufficient understanding of splicing deregulation in cancer is predicted to pave the way for novel and innovative RNA-based therapies.
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Affiliation(s)
- Ettaib El Marabti
- Biological Sciences Program, Carnegie Mellon University in Qatar, Doha, Qatar
| | - Ihab Younis
- Biological Sciences Program, Carnegie Mellon University in Qatar, Doha, Qatar
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22
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Paiva MM, Kimura ET, Coltri PP. miR18a and miR19a Recruit Specific Proteins for Splicing in Thyroid Cancer Cells. Cancer Genomics Proteomics 2018; 14:373-381. [PMID: 28871004 DOI: 10.21873/cgp.20047] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Revised: 08/07/2017] [Accepted: 08/09/2017] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND Thyroid cancer is one of the most frequent types of endocrine cancers. In most cases, thyroid cancers are caused by deregulated miRNA expression, especially involving the miR17-92 cluster. miR17-92 transcription is altered in several different tumor types including lymphoma, leukemia, and of the breast and thyroid. As an intronic cluster, miR17-92 must be processed during splicing and therefore interaction between microprocessor and spliceosome machineries is of major importance in understanding its expression. MATERIALS AND METHODS We investigated the protein composition of spliceosomes assembled on pre-RNAs containing intronic miR18a and miR19a, components of the miR17-92 cluster, using mass spectrometry. RESULTS Interestingly, we observed that proteins associated with intronic miR18a and miR19a are cell-specific, and are similar for both miRNAs analyzed. The only exception is the group of heterogeneous nuclear proteins that are commonly recruited by different cells. CONCLUSION miRNA processing depends on cell-specific proteins and heterogeneous nuclear proteins have a general role in miRNA processing from introns.
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Affiliation(s)
- Marcelo M Paiva
- Department of Cell and Developmental Biology, Institute for Biomedical Sciences, University of Sao Paulo, Sao Paulo, Brazil
| | - Edna T Kimura
- Department of Cell and Developmental Biology, Institute for Biomedical Sciences, University of Sao Paulo, Sao Paulo, Brazil
| | - Patricia P Coltri
- Department of Cell and Developmental Biology, Institute for Biomedical Sciences, University of Sao Paulo, Sao Paulo, Brazil
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23
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Site Specific Modification of Adeno-Associated Virus Enables Both Fluorescent Imaging of Viral Particles and Characterization of the Capsid Interactome. Sci Rep 2017; 7:14766. [PMID: 29116194 PMCID: PMC5676692 DOI: 10.1038/s41598-017-15255-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Accepted: 10/24/2017] [Indexed: 01/10/2023] Open
Abstract
Adeno-associated viruses (AAVs) are attractive gene therapy vectors due to their low toxicity, high stability, and rare integration into the host genome. Expressing ligands on the viral capsid can re-target AAVs to new cell types, but limited sites have been identified on the capsid that tolerate a peptide insertion. Here, we incorporated a site-specific tetracysteine sequence into the AAV serotype 9 (AAV9) capsid, to permit labelling of viral particles with either a fluorescent dye or biotin. We demonstrate that fluorescently labelled particles are detectable in vitro, and explore the utility of the method in vivo in mice with time-lapse imaging. We exploit the biotinylated viral particles to generate two distinct AAV interactomes, and identify several functional classes of proteins that are highly represented: actin/cytoskeletal protein binding, RNA binding, RNA splicing/processing, chromatin modifying, intracellular trafficking and RNA transport proteins. To examine the biological relevance of the capsid interactome, we modulated the expression of two proteins from the interactomes prior to AAV transduction. Blocking integrin αVβ6 receptor function reduced AAV9 transduction, while reducing histone deacetylase 4 (HDAC4) expression enhanced AAV transduction. Our method demonstrates a strategy for inserting motifs into the AAV capsid without compromising viral titer or infectivity.
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24
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Marques DS, Grativol J, Alves da Silva Peres R, da Rocha Matos A, Gimba ERP. Osteopontin-c isoform levels are associated with SR and hnRNP differential expression in ovarian cancer cell lines. Tumour Biol 2017; 39:1010428317725442. [PMID: 28936921 DOI: 10.1177/1010428317725442] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Osteopontin-c splicing isoform activates ovarian cancer progression features. Imbalanced expression of splicing factors from serine/arginine -rich and heterogeneous ribonucleoproteins families has been correlated with the generation of oncogenic splicing isoforms. Our goal was to investigate whether there is any association between the transcriptional patterns of these splicing factors in ovarian cells and osteopontin-c expression levels. We also aimed to investigate the occurrence of these splicing factors binding sites inside osteopontin exon 4 and adjacent introns. To test associations between osteopontin-c and splicing factors expression patterns, we used an in vitro model in which OVCAR-3 cells overexpressing osteopontin-c (OVCAR-3/OPNc++) presented higher transcriptional levels of osteopontin-c than two other ovarian carcinoma cells (TOV-112D, SKOV-3) and ovarian non-tumoral cell lines (IOSE 364 and IOSE 385). The transcriptional levels of osteopontin-c, serine/arginine-rich, and hnRNP factors were evaluated using real-time polymerase chain reaction. Human Splice Finder software was used to search for putative splicing factor binding sites in osteopontin genomic regions. OVCAR-3/OPNc++ cells presented higher transcriptional levels of hnRNP than serine/arginine-rich when compared to TOV-112D, SKOV-3, and IOSE cells. TOV-112D and SKOV-3 cells also overexpressed hnRNP in relation to serine/arginine-rich transcripts. Putative binding sites for these splicing factors have been predicted on osteopontin exon 4 and their upstream and downstream intronic regions. Our data showed that higher osteopontin-c expression levels are associated with a predominance of hnRNP in relation to serine/arginine-rich transcripts and that osteopontin exon 4 and adjacent intronic sequences contain predicted binding sites for some of these tested splicing factors. In conclusion, differential expression of these splicing factors in ovarian cancer cells could be one of the putative mechanisms leading to aberrant splicing of the osteopontin primary transcript. Future work, aiming to control ovarian cancer progression by downregulating osteopontin-c levels, could include strategies that also regulate heterogeneous ribonucleoproteins and serine/arginine-rich expression levels in order to modulate osteopontin splicing.
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Affiliation(s)
- Durval Santos Marques
- 1 Programa de Pós Graduação em Ciências Biomédicas (Fisiologia e Farmacologia), Universidade Federal Fluminense, Rio de Janeiro, Brazil
| | - Jessica Grativol
- 2 Curso de Graduação em Enfermagem, Universidade Federal Fluminense, Rio de Janeiro, Brazil
| | | | - Aline da Rocha Matos
- 3 Laboratório de Vírus Respiratórios e do Sarampo, Instituto Oswaldo Cruz, Fiocruz, Rio de Janeiro, Brazil
| | - Etel Rodrigues Pereira Gimba
- 4 Departamento de Ciências da Natureza (RCN), Instituto de Humanidades e Saúde (IHS), Universidade Federal Fluminense, Rio de Janeiro, Brazil.,5 Coordenação de Pesquisa, Programa de Pós Graduação Stricto Sensu em Oncologia do INCa, Instituto Nacional de Câncer (INCa), Rio de Janeiro, Brazil
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25
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Chen L, Weinmeister R, Kralovicova J, Eperon LP, Vorechovsky I, Hudson AJ, Eperon IC. Stoichiometries of U2AF35, U2AF65 and U2 snRNP reveal new early spliceosome assembly pathways. Nucleic Acids Res 2017; 45:2051-2067. [PMID: 27683217 PMCID: PMC5389562 DOI: 10.1093/nar/gkw860] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Accepted: 09/16/2016] [Indexed: 12/24/2022] Open
Abstract
The selection of 3΄ splice sites (3΄ss) is an essential early step in mammalian RNA splicing reactions, but the processes involved are unknown. We have used single molecule methods to test whether the major components implicated in selection, the proteins U2AF35 and U2AF65 and the U2 snRNP, are able to recognize alternative candidate sites or are restricted to one pre-specified site. In the presence of adenosine triphosphate (ATP), all three components bind in a 1:1 stoichiometry with a 3΄ss. Pre-mRNA molecules with two alternative 3΄ss can be bound concurrently by two molecules of U2AF or two U2 snRNPs, so none of the components are restricted. However, concurrent occupancy inhibits splicing. Stoichiometric binding requires conditions consistent with coalescence of the 5΄ and 3΄ sites in a complex (I, initial), but if this cannot form the components show unrestricted and stochastic association. In the absence of ATP, when complex E forms, U2 snRNP association is unrestricted. However, if protein dephosphorylation is prevented, an I-like complex forms with stoichiometric association of U2 snRNPs and the U2 snRNA is base-paired to the pre-mRNA. Complex I differs from complex A in that the formation of complex A is associated with the loss of U2AF65 and 35.
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Affiliation(s)
- Li Chen
- University of Leicester, Leicester Institute for Structural and Chemical Biology and Department of Molecular and Cell Biology, Leicester LE1 9HN, UK
| | - Robert Weinmeister
- University of Leicester, Leicester Institute for Structural and Chemical Biology and Department of Molecular and Cell Biology, Leicester LE1 9HN, UK
| | - Jana Kralovicova
- University of Southampton, Faculty of Medicine, Southampton SO16 6YD, UK
| | - Lucy P Eperon
- University of Leicester, Leicester Institute for Structural and Chemical Biology and Department of Molecular and Cell Biology, Leicester LE1 9HN, UK
| | - Igor Vorechovsky
- University of Southampton, Faculty of Medicine, Southampton SO16 6YD, UK
| | - Andrew J Hudson
- University of Leicester, Leicester Institute for Structural and Chemical Biology and Department of Chemistry, Leicester LE1 7RH, UK
| | - Ian C Eperon
- University of Leicester, Leicester Institute for Structural and Chemical Biology and Department of Molecular and Cell Biology, Leicester LE1 9HN, UK
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26
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Sperling J, Sperling R. Structural studies of the endogenous spliceosome - The supraspliceosome. Methods 2017; 125:70-83. [PMID: 28412289 PMCID: PMC5546952 DOI: 10.1016/j.ymeth.2017.04.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2016] [Revised: 04/01/2017] [Accepted: 04/10/2017] [Indexed: 12/17/2022] Open
Abstract
Pre-mRNA splicing is executed in mammalian cell nuclei within a huge (21MDa) and highly dynamic molecular machine - the supraspliceosome - that individually package pre-mRNA transcripts of different sizes and number of introns into complexes of a unique structure, indicating their universal nature. Detailed structural analysis of this huge and complex structure requires a stepwise approach using hybrid methods. Structural studies of the supraspliceosome by room temperature electron tomography, cryo-electron tomography, and scanning transmission electron microscope mass measurements revealed that it is composed of four native spliceosomes, each resembling an in vitro assembled spliceosome, which are connected by the pre-mRNA. It also elucidated the arrangement of the native spliceosomes within the intact supraspliceosome. Native spliceosomes and supraspliceosomes contain all five spliceosomal U snRNPs together with other splicing factors, and are active in splicing. The structure of the native spliceosome, at a resolution of 20Å, was determined by cryo-electron microscopy, and a unique spatial arrangement of the spliceosomal U snRNPs within the native spliceosome emerged from in silico studies. The supraspliceosome also harbor components for all pre-mRNA processing activities. Thus the supraspliceosome - the endogenous spliceosome - is a stand-alone complete macromolecular machine capable of performing splicing, alternative splicing, and encompass all nuclear pre-mRNA processing activities that the pre-mRNA has to undergo before it can exit from the nucleus to the cytoplasm to encode for protein. Further high-resolution cryo-electron microscopy studies of the endogenous spliceosome are required to decipher the regulation of alternative splicing, and elucidate the network of processing activities within it.
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Affiliation(s)
- Joseph Sperling
- Department of Organic Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Ruth Sperling
- Department of Genetics, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.
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27
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Climente-González H, Porta-Pardo E, Godzik A, Eyras E. The Functional Impact of Alternative Splicing in Cancer. Cell Rep 2017; 20:2215-2226. [DOI: 10.1016/j.celrep.2017.08.012] [Citation(s) in RCA: 358] [Impact Index Per Article: 51.1] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Revised: 07/15/2017] [Accepted: 07/26/2017] [Indexed: 12/29/2022] Open
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28
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Normal and altered pre-mRNA processing in the DMD gene. Hum Genet 2017; 136:1155-1172. [DOI: 10.1007/s00439-017-1820-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Accepted: 06/02/2017] [Indexed: 12/11/2022]
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29
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Fujita T, Higashitsuji H, Higashitsuji H, Liu Y, Itoh K, Sakurai T, Kojima T, Kandori S, Nishiyama H, Fukumoto M, Fukumoto M, Shibasaki K, Fujita J. TRPV4-dependent induction of a novel mammalian cold-inducible protein SRSF5 as well as CIRP and RBM3. Sci Rep 2017; 7:2295. [PMID: 28536481 PMCID: PMC5442135 DOI: 10.1038/s41598-017-02473-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2016] [Accepted: 04/11/2017] [Indexed: 02/06/2023] Open
Abstract
Cold-inducible RNA-binding protein (CIRP) and RNA-binding motif protein 3 (RBM3) are two evolutionarily conserved RNA-binding proteins that are structurally related to hnRNPs and upregulated in response to moderately low temperatures in mammalian cells. Although contributions of splicing efficiency, the gene promoters activated upon mild hypothermia and the transcription factor Sp1 to induction of CIRP have been reported, precise mechanisms by which hypothermia and other stresses induce the expression of mammalian cold-inducible proteins (CIPs) are poorly understood. By screening the serine/arginine-rich splicing factors (SRSFs), we report that the transcript and protein levels of SRSF5 were increased in mammalian cells cultured at 32 °C. Expression of SRSF5 as well as CIRP and RBM3 were also induced by DNA damage, hypoxia, cycloheximide and hypotonicity. Immunohistochemical studies demonstrated that SRSF5 was constitutively expressed in male germ cells and the level was decreased in human testicular germ cell tumors. SRSF5 facilitated production of p19 H-RAS, and increased sensitivity to doxorubicin in human U-2 OS cells. Induction of CIPs was dependent on transient receptor potential vanilloid 4 (TRPV4) channel protein, but seemed independent of its ion channel activity. These findings indicate a previously unappreciated role for the TRP protein in linking environmental stress to splicing.
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Affiliation(s)
- Takanori Fujita
- Department of Clinical Molecular Biology, Graduate School of Medicine, Kyoto University, Kyoto, Kyoto, 606-8507, Japan.,School of Economics, Nagoya University, Nagoya, Nagoya, 464-8601, Japan
| | - Hiroaki Higashitsuji
- Department of Clinical Molecular Biology, Graduate School of Medicine, Kyoto University, Kyoto, Kyoto, 606-8507, Japan
| | - Hisako Higashitsuji
- Department of Clinical Molecular Biology, Graduate School of Medicine, Kyoto University, Kyoto, Kyoto, 606-8507, Japan
| | - Yu Liu
- Department of Clinical Molecular Biology, Graduate School of Medicine, Kyoto University, Kyoto, Kyoto, 606-8507, Japan
| | - Katsuhiko Itoh
- Department of Clinical Molecular Biology, Graduate School of Medicine, Kyoto University, Kyoto, Kyoto, 606-8507, Japan
| | - Toshiharu Sakurai
- Department of Gastroenterology and Hepatology, Kindai University Faculty of Medicine, Osaka-Sayama, Osaka, 589-8511, Japan
| | - Takahiro Kojima
- Department of Urology, Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki, 305-8575, Japan
| | - Shuya Kandori
- Department of Urology, Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki, 305-8575, Japan
| | - Hiroyuki Nishiyama
- Department of Urology, Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki, 305-8575, Japan
| | - Motoi Fukumoto
- Department of Pathology, Institute of Development, Aging and Cancer, Tohoku University, Sendai, Miyagi, 980-8575, Japan
| | - Manabu Fukumoto
- Department of Pathology, Institute of Development, Aging and Cancer, Tohoku University, Sendai, Miyagi, 980-8575, Japan.,Department of Molecular Pathology, Tokyo Medical University, Shinjuku-ku, Tokyo, 160-8402, Japan
| | - Koji Shibasaki
- Department of Molecular and Cellular Neurobiology, Gunma University Graduate School of Medicine, Maebashi, Gunma, 371-8511, Japan
| | - Jun Fujita
- Department of Clinical Molecular Biology, Graduate School of Medicine, Kyoto University, Kyoto, Kyoto, 606-8507, Japan. .,Department of Rehabilitation Medicine, Biwako-Chuo Hospital, Otsu, Shiga, 520-0834, Japan.
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30
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Sperling R. The nuts and bolts of the endogenous spliceosome. WILEY INTERDISCIPLINARY REVIEWS-RNA 2016; 8. [PMID: 27465259 DOI: 10.1002/wrna.1377] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Revised: 06/14/2016] [Accepted: 06/15/2016] [Indexed: 01/09/2023]
Abstract
The complex life of pre-mRNA from transcription to the production of mRNA that can be exported from the nucleus to the cytoplasm to encode for proteins entails intricate coordination and regulation of a network of processing events. Coordination is required between transcription and splicing and between several processing events including 5' and 3' end processing, splicing, alternative splicing and editing that are major contributors to the diversity of the human proteome, and occur within a huge and dynamic macromolecular machine-the endogenous spliceosome. Detailed mechanistic insight of the splicing reaction was gained from studies of the in vitro spliceosome assembled on a single intron. Because most pre-mRNAs are multiintronic that undergo alternative splicing, the in vivo splicing machine requires additional elements to those of the in vitro machine, to account for all these diverse functions. Information about the endogenous spliceosome is emerging from imaging studies in intact and live cells that support the cotranscriptional commitment to splicing model and provide information about splicing kinetics in vivo. Another source comes from studies of the in vivo assembled spliceosome, isolated from cell nuclei under native conditions-the supraspliceosome-that individually package pre-mRNA transcripts of different sizes and number of introns into complexes of a unique structure, indicating their universal nature. Recent years have portrayed new players affecting alternative splicing and novel connections between splicing, transcription and chromatin. The challenge ahead is to elucidate the structure and function of the endogenous spliceosome and decipher the regulation and coordination of its network of processing activities. WIREs RNA 2017, 8:e1377. doi: 10.1002/wrna.1377 For further resources related to this article, please visit the WIREs website.
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Affiliation(s)
- Ruth Sperling
- Department of Genetics, The Hebrew University of Jerusalem, Jerusalem, Israel
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31
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Anczuków O, Akerman M, Cléry A, Wu J, Shen C, Shirole NH, Raimer A, Sun S, Jensen MA, Hua Y, Allain FHT, Krainer AR. SRSF1-Regulated Alternative Splicing in Breast Cancer. Mol Cell 2015; 60:105-17. [PMID: 26431027 PMCID: PMC4597910 DOI: 10.1016/j.molcel.2015.09.005] [Citation(s) in RCA: 236] [Impact Index Per Article: 26.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Revised: 07/24/2015] [Accepted: 08/28/2015] [Indexed: 12/28/2022]
Abstract
Splicing factor SRSF1 is upregulated in human breast tumors, and its overexpression promotes transformation of mammary cells. Using RNA-seq, we identified SRSF1-regulated alternative splicing (AS) targets in organotypic three-dimensional MCF-10A cell cultures that mimic a context relevant to breast cancer. We identified and validated hundreds of endogenous SRSF1-regulated AS events. De novo discovery of the SRSF1 binding motif reconciled discrepancies in previous motif analyses. Using a Bayesian model, we determined positional effects of SRSF1 binding on cassette exons: binding close to the 5' splice site generally promoted exon inclusion, whereas binding near the 3' splice site promoted either exon skipping or inclusion. Finally, we identified SRSF1-regulated AS events deregulated in human tumors; overexpressing one such isoform, exon-9-included CASC4, increased acinar size and proliferation, and decreased apoptosis, partially recapitulating SRSF1's oncogenic effects. Thus, we uncovered SRSF1 positive and negative regulatory mechanisms, and oncogenic AS events that represent potential targets for therapeutics development.
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Affiliation(s)
- Olga Anczuków
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA
| | - Martin Akerman
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA
| | - Antoine Cléry
- Institute for Molecular Biology and Biophysics, Department of Biology, ETH Zurich, 8093 Zurich, Switzerland
| | - Jie Wu
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA; Department of Applied Mathematics and Statistics, Stony Brook University, Stony Brook, NY 11794, USA
| | - Chen Shen
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA; Molecular and Cellular Biology Program, Stony Brook University, Stony Brook, NY 11794, USA
| | - Nitin H Shirole
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA; Graduate Program in Genetics, Stony Brook University, Stony Brook, NY 11794, USA
| | - Amanda Raimer
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA
| | - Shuying Sun
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA
| | - Mads A Jensen
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA
| | - Yimin Hua
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA
| | - Frédéric H-T Allain
- Institute for Molecular Biology and Biophysics, Department of Biology, ETH Zurich, 8093 Zurich, Switzerland
| | - Adrian R Krainer
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA.
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32
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Abstract
The spliceosome is a huge molecular machine that assembles dynamically onto its pre-mRNA substrates. A new study based on interactome analysis provides clues about how splicing-regulatory proteins modulate assembly of the spliceosome to either activate or repress splicing. Please see related Research article: http://www.genomebiology.com/2015/16/1/119/abstract
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Affiliation(s)
- Daniel Dominguez
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, 02142, USA
| | - Christopher B Burge
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, 02142, USA. .,Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02142, USA.
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