1
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Kikuchi M, Viet J, Nagata K, Sato M, David G, Audic Y, Silverman MA, Yamamoto M, Akatsu H, Hashizume Y, Takeda S, Akamine S, Miyamoto T, Uozumi R, Gotoh S, Mori K, Ikeda M, Paillard L, Morihara T. Gene-gene functional relationships in Alzheimer's disease: CELF1 regulates KLC1 alternative splicing. Biochem Biophys Res Commun 2024; 721:150025. [PMID: 38768546 DOI: 10.1016/j.bbrc.2024.150025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2024] [Revised: 04/16/2024] [Accepted: 04/26/2024] [Indexed: 05/22/2024]
Abstract
The causes of Alzheimer's disease (AD) are poorly understood, although many genes are known to be involved in this pathology. To gain insights into the underlying molecular mechanisms, it is essential to identify the relationships between individual AD genes. Previous work has shown that the splice variant E of KLC1 (KLC1_vE) promotes AD, and that the CELF1 gene, which encodes an RNA-binding protein involved in splicing regulation, is at a risk locus for AD. Here, we identified a functional link between CELF1 and KLC1 in AD pathogenesis. Transcriptomic data from human samples from different ethnic groups revealed that CELF1 mRNA levels are low in AD brains, and the splicing pattern of KLC1 is strongly correlated with CELF1 expression levels. Specifically, KLC1_vE is negatively correlated with CELF1. Depletion and overexpression experiments in cultured cells demonstrated that the CELF1 protein down-regulates KLC1_vE. In a cross-linking and immunoprecipitation sequencing (CLIP-seq) database, CELF1 directly binds to KLC1 RNA, following which it likely modulates terminal exon usage, hence KLC1_vE formation. These findings reveal a new pathogenic pathway where a risk allele of CELF1 is associated with reduced CELF1 expression, which up-regulates KLC1_vE to promote AD.
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Affiliation(s)
- Masataka Kikuchi
- Department of Genome Informatics, Graduate School of Medicine, Osaka University, Suita, Japan
| | - Justine Viet
- Université de Rennes, CNRS, IGDR (Institut de Génétique et Développement de Rennes), UMR 6290, F-35000, Rennes, France
| | - Kenichi Nagata
- Department of Functional Anatomy and Neuroscience, Graduate School of Medicine, Nagoya University, Nagoya, Japan
| | - Masahiro Sato
- Department of Psychiatry, Graduate School of Medicine, Osaka University, Suita, Japan
| | - Geraldine David
- Université de Rennes, CNRS, IGDR (Institut de Génétique et Développement de Rennes), UMR 6290, F-35000, Rennes, France
| | - Yann Audic
- Université de Rennes, CNRS, IGDR (Institut de Génétique et Développement de Rennes), UMR 6290, F-35000, Rennes, France
| | - Michael A Silverman
- Department of Biological Sciences, Centre for Cell Biology, Development, and Disease, Simon Fraser University, Burnaby, Canada
| | - Mitsuko Yamamoto
- Department of Psychiatry, Graduate School of Medicine, Osaka University, Suita, Japan
| | - Hiroyasu Akatsu
- Department of Community-based Medical Education, Graduate School of Medicine, Nagoya City University, Nagoya, Japan; Choju Medical/Neuropathological Institute, Fukushimura Hospital, Toyohashi, Japan
| | | | - Shuko Takeda
- Department of Clinical Gene Therapy, Graduate School of Medicine, Osaka University, Suita, Japan; Osaka Psychiatric Medical Center, Osaka Psychiatric Research Center, Hirakata, Japan
| | - Shoshin Akamine
- Department of Psychiatry, Graduate School of Medicine, Osaka University, Suita, Japan
| | - Tesshin Miyamoto
- Department of Psychiatry, Graduate School of Medicine, Osaka University, Suita, Japan
| | - Ryota Uozumi
- Department of Psychiatry, Graduate School of Medicine, Osaka University, Suita, Japan
| | - Shiho Gotoh
- Department of Psychiatry, Graduate School of Medicine, Osaka University, Suita, Japan
| | - Kohji Mori
- Department of Psychiatry, Graduate School of Medicine, Osaka University, Suita, Japan
| | - Manabu Ikeda
- Department of Psychiatry, Graduate School of Medicine, Osaka University, Suita, Japan
| | - Luc Paillard
- Université de Rennes, CNRS, IGDR (Institut de Génétique et Développement de Rennes), UMR 6290, F-35000, Rennes, France.
| | - Takashi Morihara
- Department of Psychiatry, Graduate School of Medicine, Osaka University, Suita, Japan; Toyonaka Municipal Hospital, Toyonaka, Japan.
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2
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De Silva N, Lehman N, Fargason T, Paul T, Zhang Z, Zhang J. Unearthing a novel function of SRSF1 in binding and unfolding of RNA G-quadruplexes. Nucleic Acids Res 2024; 52:4676-4690. [PMID: 38567732 PMCID: PMC11077049 DOI: 10.1093/nar/gkae213] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2023] [Revised: 02/28/2024] [Accepted: 03/13/2024] [Indexed: 04/14/2024] Open
Abstract
SRSF1 governs splicing of over 1500 mRNA transcripts. SRSF1 contains two RNA-recognition motifs (RRMs) and a C-terminal Arg/Ser-rich region (RS). It has been thought that SRSF1 RRMs exclusively recognize single-stranded exonic splicing enhancers, while RS lacks RNA-binding specificity. With our success in solving the insolubility problem of SRSF1, we can explore the unknown RNA-binding landscape of SRSF1. We find that SRSF1 RS prefers purine over pyrimidine. Moreover, SRSF1 binds to the G-quadruplex (GQ) from the ARPC2 mRNA, with both RRMs and RS being crucial. Our binding assays show that the traditional RNA-binding sites on the RRM tandem and the Arg in RS are responsible for GQ binding. Interestingly, our FRET and circular dichroism data reveal that SRSF1 unfolds the ARPC2 GQ, with RS leading unfolding and RRMs aiding. Our saturation transfer difference NMR results discover that Arg residues in SRSF1 RS interact with the guanine base but not other nucleobases, underscoring the uniqueness of the Arg/guanine interaction. Our luciferase assays confirm that SRSF1 can alleviate the inhibitory effect of GQ on gene expression in the cell. Given the prevalence of RNA GQ and SR proteins, our findings unveil unexplored SR protein functions with broad implications in RNA splicing and translation.
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Affiliation(s)
- Naiduwadura Ivon Upekala De Silva
- Department of Chemistry, College of Arts and Sciences, University of Alabama at Birmingham, CH266, 901 14th Street South, Birmingham, AL 35294-1240, USA
| | - Nathan Lehman
- Department of Chemistry, College of Arts and Sciences, University of Alabama at Birmingham, CH266, 901 14th Street South, Birmingham, AL 35294-1240, USA
| | - Talia Fargason
- Department of Chemistry, College of Arts and Sciences, University of Alabama at Birmingham, CH266, 901 14th Street South, Birmingham, AL 35294-1240, USA
| | - Trenton Paul
- Department of Chemistry, College of Arts and Sciences, University of Alabama at Birmingham, CH266, 901 14th Street South, Birmingham, AL 35294-1240, USA
| | - Zihan Zhang
- Department of Chemistry, College of Arts and Sciences, University of Alabama at Birmingham, CH266, 901 14th Street South, Birmingham, AL 35294-1240, USA
| | - Jun Zhang
- Department of Chemistry, College of Arts and Sciences, University of Alabama at Birmingham, CH266, 901 14th Street South, Birmingham, AL 35294-1240, USA
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3
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De Silva NIU, Lehman N, Fargason T, Paul T, Zhang Z, Zhang J. Unearthing SRSF1's Novel Function in Binding and Unfolding of RNA G-Quadruplexes. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.30.563137. [PMID: 37961538 PMCID: PMC10634998 DOI: 10.1101/2023.10.30.563137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
SRSF1 governs splicing of over 1,500 mRNA transcripts. SRSF1 contains two RNA-recognition motifs (RRMs) and a C-terminal Arg/Ser-rich region (RS). It has been thought that SRSF1 RRMs exclusively recognize single-stranded exonic splicing enhancers, while RS lacks RNA-binding specificity. With our success in solving the insolubility problem of SRSF1, we can explore the unknown RNA-binding landscape of SRSF1. We find that SRSF1 RS prefers purine over pyrimidine. Moreover, SRSF1 binds to the G-quadruplex (GQ) from the ARPC2 mRNA, with both RRMs and RS being crucial. Our binding assays show that the traditional RNA-binding sites on the RRM tandem and the Arg in RS are responsible for GQ binding. Interestingly, our FRET and circular dichroism data reveal that SRSF1 unfolds the ARPC2 GQ, with RS leading unfolding and RRMs aiding. Our saturation transfer difference NMR results discover that Arg residues in SRSF1 RS interact with the guanine base but other nucleobases, underscoring the uniqueness of the Arg/guanine interaction. Our luciferase assays confirm that SRSF1 can alleviate the inhibitory effect of GQ on gene expression in the cell. Given the prevalence of RNA GQ and SR proteins, our findings unveil unexplored SR protein functions with broad implications in RNA splicing and translation.
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Affiliation(s)
- Naiduwadura Ivon Upekala De Silva
- Department of Chemistry, College of Arts and Sciences, University of Alabama at Birmingham, CH266, 901 14th Street South, Birmingham, AL, 35294-1240, USA
| | - Nathan Lehman
- Department of Chemistry, College of Arts and Sciences, University of Alabama at Birmingham, CH266, 901 14th Street South, Birmingham, AL, 35294-1240, USA
| | - Talia Fargason
- Department of Chemistry, College of Arts and Sciences, University of Alabama at Birmingham, CH266, 901 14th Street South, Birmingham, AL, 35294-1240, USA
| | - Trenton Paul
- Department of Chemistry, College of Arts and Sciences, University of Alabama at Birmingham, CH266, 901 14th Street South, Birmingham, AL, 35294-1240, USA
| | - Zihan Zhang
- Department of Chemistry, College of Arts and Sciences, University of Alabama at Birmingham, CH266, 901 14th Street South, Birmingham, AL, 35294-1240, USA
| | - Jun Zhang
- Department of Chemistry, College of Arts and Sciences, University of Alabama at Birmingham, CH266, 901 14th Street South, Birmingham, AL, 35294-1240, USA
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4
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Joudaki A, Takeda JI, Masuda A, Ode R, Fujiwara K, Ohno K. FexSplice: A LightGBM-Based Model for Predicting the Splicing Effect of a Single Nucleotide Variant Affecting the First Nucleotide G of an Exon. Genes (Basel) 2023; 14:1765. [PMID: 37761905 PMCID: PMC10531444 DOI: 10.3390/genes14091765] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Revised: 08/30/2023] [Accepted: 09/04/2023] [Indexed: 09/29/2023] Open
Abstract
Single nucleotide variants (SNVs) affecting the first nucleotide G of an exon (Fex-SNVs) identified in various diseases are mostly recognized as missense or nonsense variants. Their effect on pre-mRNA splicing has been seldom analyzed, and no curated database is available. We previously reported that Fex-SNVs affect splicing when the length of the polypyrimidine tract is short or degenerate. However, we cannot readily predict the splicing effects of Fex-SNVs. We here scrutinized the available literature and identified 106 splicing-affecting Fex-SNVs based on experimental evidence. We similarly identified 106 neutral Fex-SNVs in the dbSNP database with a global minor allele frequency (MAF) of more than 0.01 and less than 0.50. We extracted 115 features representing the strength of splicing cis-elements and developed machine-learning models with support vector machine, random forest, and gradient boosting to discriminate splicing-affecting and neutral Fex-SNVs. Gradient boosting-based LightGBM outperformed the other two models, and the length and nucleotide compositions of the polypyrimidine tract played critical roles in the discrimination. Recursive feature elimination showed that the LightGBM model using 15 features achieved the best performance with an accuracy of 0.80 ± 0.12 (mean and SD), a Matthews Correlation Coefficient (MCC) of 0.57 ± 0.15, an area under the curve of the receiver operating characteristics curve (AUROC) of 0.86 ± 0.08, and an area under the curve of the precision-recall curve (AUPRC) of 0.87 ± 0.09 using a 10-fold cross-validation. We developed a web service program, named FexSplice that accepts a genomic coordinate either on GRCh37/hg19 or GRCh38/hg38 and returns a predicted probability of aberrant splicing of A, C, and T variants.
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Affiliation(s)
- Atefeh Joudaki
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, 65 Tsurumai, Showa-ku, Nagoya 466-8550, Japan; (A.J.); (J.-i.T.); (A.M.)
| | - Jun-ichi Takeda
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, 65 Tsurumai, Showa-ku, Nagoya 466-8550, Japan; (A.J.); (J.-i.T.); (A.M.)
| | - Akio Masuda
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, 65 Tsurumai, Showa-ku, Nagoya 466-8550, Japan; (A.J.); (J.-i.T.); (A.M.)
| | - Rikumo Ode
- Department of Materials Science and Engineering, Nagoya University Graduate School of Engineering, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan; (R.O.); (K.F.)
| | - Koichi Fujiwara
- Department of Materials Science and Engineering, Nagoya University Graduate School of Engineering, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan; (R.O.); (K.F.)
| | - Kinji Ohno
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, 65 Tsurumai, Showa-ku, Nagoya 466-8550, Japan; (A.J.); (J.-i.T.); (A.M.)
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5
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Zeng Y, Fair BJ, Zeng H, Krishnamohan A, Hou Y, Hall JM, Ruthenburg AJ, Li YI, Staley JP. Profiling lariat intermediates reveals genetic determinants of early and late co-transcriptional splicing. Mol Cell 2022; 82:4681-4699.e8. [PMID: 36435176 PMCID: PMC10448999 DOI: 10.1016/j.molcel.2022.11.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Revised: 09/10/2022] [Accepted: 11/02/2022] [Indexed: 11/27/2022]
Abstract
Long introns with short exons in vertebrate genes are thought to require spliceosome assembly across exons (exon definition), rather than introns, thereby requiring transcription of an exon to splice an upstream intron. Here, we developed CoLa-seq (co-transcriptional lariat sequencing) to investigate the timing and determinants of co-transcriptional splicing genome wide. Unexpectedly, 90% of all introns, including long introns, can splice before transcription of a downstream exon, indicating that exon definition is not obligatory for most human introns. Still, splicing timing varies dramatically across introns, and various genetic elements determine this variation. Strong U2AF2 binding to the polypyrimidine tract predicts early splicing, explaining exon definition-independent splicing. Together, our findings question the essentiality of exon definition and reveal features beyond intron and exon length that are determinative for splicing timing.
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Affiliation(s)
- Yi Zeng
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637, USA
| | - Benjamin J Fair
- Department of Medicine, University of Chicago, Chicago, IL 60637, USA
| | - Huilin Zeng
- 855 Jefferson Ave. Redwood City, CA 94063, USA
| | - Aiswarya Krishnamohan
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637, USA
| | - Yichen Hou
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637, USA
| | - Johnathon M Hall
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637, USA
| | - Alexander J Ruthenburg
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637, USA; Department of Biochemistry & Molecular Biology, University of Chicago, Chicago, IL 60637, USA
| | - Yang I Li
- Department of Medicine, University of Chicago, Chicago, IL 60637, USA; Department of Human Genetics, University of Chicago, Chicago, IL 60637, USA.
| | - Jonathan P Staley
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637, USA.
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6
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Xiong F, Ren JJ, Wang YY, Zhou Z, Qi HD, Otegui MS, Wang XL. An Arabidopsis Retention and Splicing complex regulates root and embryo development through pre-mRNA splicing. PLANT PHYSIOLOGY 2022; 190:621-639. [PMID: 35640107 PMCID: PMC9434225 DOI: 10.1093/plphys/kiac256] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Accepted: 05/08/2022] [Indexed: 05/30/2023]
Abstract
Pre-mRNA splicing is an important step in the posttranscriptional processing of transcripts and a key regulator of development. The heterotrimeric retention and splicing (RES) complex plays vital roles in the growth and development of yeast, zebrafish, and humans by mediating pre-mRNA splicing of multiple genes. However, whether the RES complex is conserved in plants and what specific functions it has remain unknown. In this study, we identified Arabidopsis (Arabidopsis thaliana) BUD13 (AtBUD13), GROWTH, DEVELOPMENT AND SPLICING 1 (GDS1), and DAWDLE (DDL) as the counterparts of the yeast RES complex subunits Bud site selection protein 13 (Bud13), U2 snRNP component Snu17 (Snu17), and Pre-mRNA leakage protein 1, respectively. Moreover, we showed that RES is an ancient complex evolutionarily conserved in eukaryotes. GDS1 directly interacts with both AtBUD13 and DDL in nuclear speckles. The BUD13 domain of AtBUD13 and the RNA recognition motif domain of GDS1 are necessary and sufficient for AtBUD13-GDS1 interaction. Mutants of AtBUD13, GDS1, and DDL failed to properly splice multiple genes involved in cell proliferation and showed defects in early embryogenesis and root development. In addition, we found that GDS1 and DDL interact, respectively, with the U2 small nuclear ribonucleoproteins auxiliary factor AtU2AF65B and the NineTeen Complex-related splicing factor SKIP, which are essential for early steps of spliceosome assembly and recognition of splice sites. Altogether, our work reveals that the Arabidopsis RES complex is important for root and early embryo development by modulating pre-mRNA splicing.
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Affiliation(s)
- Feng Xiong
- National Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Taian 271018, China
| | - Jing-Jing Ren
- National Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Taian 271018, China
| | - Yu-Yi Wang
- National Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Taian 271018, China
| | - Zhou Zhou
- National Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Taian 271018, China
| | - Hao-Dong Qi
- National Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Taian 271018, China
| | - Marisa S Otegui
- Department of Botany, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
- Center for Quantitative Cell Imaging, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
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7
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Glasser E, Maji D, Biancon G, Puthenpeedikakkal A, Cavender C, Tebaldi T, Jenkins J, Mathews D, Halene S, Kielkopf C. Pre-mRNA splicing factor U2AF2 recognizes distinct conformations of nucleotide variants at the center of the pre-mRNA splice site signal. Nucleic Acids Res 2022; 50:5299-5312. [PMID: 35524551 PMCID: PMC9128377 DOI: 10.1093/nar/gkac287] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Revised: 04/03/2022] [Accepted: 04/12/2022] [Indexed: 11/24/2022] Open
Abstract
The essential pre-mRNA splicing factor U2AF2 (also called U2AF65) identifies polypyrimidine (Py) tract signals of nascent transcripts, despite length and sequence variations. Previous studies have shown that the U2AF2 RNA recognition motifs (RRM1 and RRM2) preferentially bind uridine-rich RNAs. Nonetheless, the specificity of the RRM1/RRM2 interface for the central Py tract nucleotide has yet to be investigated. We addressed this question by determining crystal structures of U2AF2 bound to a cytidine, guanosine, or adenosine at the central position of the Py tract, and compared U2AF2-bound uridine structures. Local movements of the RNA site accommodated the different nucleotides, whereas the polypeptide backbone remained similar among the structures. Accordingly, molecular dynamics simulations revealed flexible conformations of the central, U2AF2-bound nucleotide. The RNA binding affinities and splicing efficiencies of structure-guided mutants demonstrated that U2AF2 tolerates nucleotide substitutions at the central position of the Py tract. Moreover, enhanced UV-crosslinking and immunoprecipitation of endogenous U2AF2 in human erythroleukemia cells showed uridine-sensitive binding sites, with lower sequence conservation at the central nucleotide positions of otherwise uridine-rich, U2AF2-bound splice sites. Altogether, these results highlight the importance of RNA flexibility for protein recognition and take a step towards relating splice site motifs to pre-mRNA splicing efficiencies.
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Affiliation(s)
- Eliezra Glasser
- Department of Biochemistry and Biophysics, and the Center for
RNA Biology, University of Rochester School of Medicine and
Dentistry, Rochester,
NY 14642, USA
| | - Debanjana Maji
- Department of Biochemistry and Biophysics, and the Center for
RNA Biology, University of Rochester School of Medicine and
Dentistry, Rochester,
NY 14642, USA
| | - Giulia Biancon
- Section of Hematology, Department of Internal Medicine and
Yale Cancer Center, Yale University School of Medicine,
New Haven,
CT 06520, USA
| | | | - Chapin E Cavender
- Department of Biochemistry and Biophysics, and the Center for
RNA Biology, University of Rochester School of Medicine and
Dentistry, Rochester,
NY 14642, USA
| | - Toma Tebaldi
- Section of Hematology, Department of Internal Medicine and
Yale Cancer Center, Yale University School of Medicine,
New Haven,
CT 06520, USA
- Department of Cellular, Computational and Integrative Biology
(CIBIO), University of
Trento, Trento, Italy
| | - Jermaine L Jenkins
- Department of Biochemistry and Biophysics, and the Center for
RNA Biology, University of Rochester School of Medicine and
Dentistry, Rochester,
NY 14642, USA
| | - David H Mathews
- Department of Biochemistry and Biophysics, and the Center for
RNA Biology, University of Rochester School of Medicine and
Dentistry, Rochester,
NY 14642, USA
| | - Stephanie Halene
- Section of Hematology, Department of Internal Medicine and
Yale Cancer Center, Yale University School of Medicine,
New Haven,
CT 06520, USA
- Yale Center for RNA Science and Medicine, Yale University
School of Medicine, New Haven,
CT 06520, USA
- Department of Pathology, Yale University School of
Medicine, New Haven,
CT 06520, USA
| | - Clara L Kielkopf
- Department of Biochemistry and Biophysics, and the Center for
RNA Biology, University of Rochester School of Medicine and
Dentistry, Rochester,
NY 14642, USA
- Wilmot Cancer Institute, University of Rochester School of
Medicine and Dentistry, Rochester,
NY 14642, USA
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8
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Sette C, Paronetto MP. Somatic Mutations in Core Spliceosome Components Promote Tumorigenesis and Generate an Exploitable Vulnerability in Human Cancer. Cancers (Basel) 2022; 14:cancers14071827. [PMID: 35406598 PMCID: PMC8997811 DOI: 10.3390/cancers14071827] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Revised: 03/30/2022] [Accepted: 03/30/2022] [Indexed: 12/02/2022] Open
Abstract
Simple Summary High throughput exome sequencing approaches have disclosed recurrent cancer-associated mutations in spliceosomal components, which drive aberrant pre-mRNA processing events and support the tumor phenotype. At the same time, mutations in spliceosome genes and aberrant splicing regulation establish a selective vulnerability of cancer cells to splicing-targeting approaches, which could be exploited therapeutically. It is conceivable that a better understanding of the mechanisms and roles of abnormal splicing in tumor metabolism will facilitate the development of a novel generation of tumor-targeting drugs. In this review, we describe recent advances in the elucidation of the biological impact and biochemical effects of somatic mutations in core spliceosome components on splicing choices and their associated targetable vulnerabilities. Abstract Alternative pre-mRNA processing enables the production of distinct mRNA and protein isoforms from a single gene, thus greatly expanding the coding potential of eukaryotic genomes and fine-tuning gene expression programs. Splicing is carried out by the spliceosome, a complex molecular machinery which assembles step-wise on mRNA precursors in the nucleus of eukaryotic cells. In the last decade, exome sequencing technologies have allowed the identification of point mutations in genes encoding splicing factors as a recurrent hallmark of human cancers, with higher incidence in hematological malignancies. These mutations lead to production of splicing factors that reduce the fidelity of the splicing process and yield splicing variants that are often advantageous for cancer cells. However, at the same time, these mutations increase the sensitivity of transformed cells to splicing inhibitors, thus offering a therapeutic opportunity for novel targeted strategies. Herein, we review the recent literature documenting cancer-associated mutations in components of the early spliceosome complex and discuss novel therapeutic strategies based on small-molecule spliceosome inhibitors that exhibit strong anti-tumor effects, particularly against cancer cells harboring mutations in spliceosomal components.
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Affiliation(s)
- Claudio Sette
- Department of Neuroscience, Section of Human Anatomy, Catholic University of the Sacred Heart, 00168 Rome, Italy;
- GSTEP-Organoids Core Facility, Fondazione Policlinico Agostino Gemelli IRCCS, 00168 Rome, Italy
| | - Maria Paola Paronetto
- Department of Movement, Human and Health Sciences, University of Rome “Foro Italico”, Piazza Lauro De Bosis, 6, 00135 Rome, Italy
- Laboratory of Molecular and Cellular Neurobiology, Fondazione Santa Lucia, IRCCS, Via del Fosso di Fiorano 64, 00143 Rome, Italy
- Correspondence:
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9
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Borao S, Ayté J, Hümmer S. Evolution of the Early Spliceosomal Complex-From Constitutive to Regulated Splicing. Int J Mol Sci 2021; 22:ijms222212444. [PMID: 34830325 PMCID: PMC8624252 DOI: 10.3390/ijms222212444] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Revised: 11/15/2021] [Accepted: 11/16/2021] [Indexed: 12/14/2022] Open
Abstract
Pre-mRNA splicing is a major process in the regulated expression of genes in eukaryotes, and alternative splicing is used to generate different proteins from the same coding gene. Splicing is a catalytic process that removes introns and ligates exons to create the RNA sequence that codifies the final protein. While this is achieved in an autocatalytic process in ancestral group II introns in prokaryotes, the spliceosome has evolved during eukaryogenesis to assist in this process and to finally provide the opportunity for intron-specific splicing. In the early stage of splicing, the RNA 5' and 3' splice sites must be brought within proximity to correctly assemble the active spliceosome and perform the excision and ligation reactions. The assembly of this first complex, termed E-complex, is currently the least understood process. We focused in this review on the formation of the E-complex and compared its composition and function in three different organisms. We highlight the common ancestral mechanisms in S. cerevisiae, S. pombe, and mammals and conclude with a unifying model for intron definition in constitutive and regulated co-transcriptional splicing.
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Affiliation(s)
- Sonia Borao
- Oxidative Stress and Cell Cycle Group, Universitat Pompeu Fabra, 08003 Barcelona, Spain;
| | - José Ayté
- Oxidative Stress and Cell Cycle Group, Universitat Pompeu Fabra, 08003 Barcelona, Spain;
- Correspondence: (J.A.); (S.H.)
| | - Stefan Hümmer
- Oxidative Stress and Cell Cycle Group, Universitat Pompeu Fabra, 08003 Barcelona, Spain;
- Translational Molecular Pathology, Vall d’Hebron Research Institute (VHIR), CIBERONC, 08035 Barcelona, Spain
- Correspondence: (J.A.); (S.H.)
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10
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Hümmer S, Borao S, Guerra-Moreno A, Cozzuto L, Hidalgo E, Ayté J. Cross talk between the upstream exon-intron junction and Prp2 facilitates splicing of non-consensus introns. Cell Rep 2021; 37:109893. [PMID: 34706246 DOI: 10.1016/j.celrep.2021.109893] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Revised: 04/27/2021] [Accepted: 10/06/2021] [Indexed: 10/20/2022] Open
Abstract
Splicing of mRNA precursors is essential in the regulation of gene expression. U2AF65 recognizes the poly-pyrimidine tract and helps in the recognition of the branch point. Inactivation of fission yeast U2AF65 (Prp2) blocks splicing of most, but not all, pre-mRNAs, for reasons that are not understood. Here, we have determined genome-wide the splicing efficiency of fission yeast cells as they progress into synchronous meiosis in the presence or absence of functional Prp2. Our data indicate that in addition to the splicing elements at the 3' end of any intron, the nucleotides immediately upstream the intron will determine whether Prp2 is required or dispensable for splicing. By changing those nucleotides in any given intron, we regulate its Prp2 dependency. Our results suggest a model in which Prp2 is required for the coordinated recognition of both intronic ends, placing Prp2 as a key regulatory element in the determination of the exon-intron boundaries.
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Affiliation(s)
- Stefan Hümmer
- Oxidative Stress and Cell Cycle Group, Universitat Pompeu Fabra, 08003 Barcelona, Spain.
| | - Sonia Borao
- Oxidative Stress and Cell Cycle Group, Universitat Pompeu Fabra, 08003 Barcelona, Spain
| | - Angel Guerra-Moreno
- Oxidative Stress and Cell Cycle Group, Universitat Pompeu Fabra, 08003 Barcelona, Spain
| | - Luca Cozzuto
- CRG Bioinformatics Core, Centre de Regulació Genòmica (CRG), 08003 Barcelona, Spain
| | - Elena Hidalgo
- Oxidative Stress and Cell Cycle Group, Universitat Pompeu Fabra, 08003 Barcelona, Spain
| | - José Ayté
- Oxidative Stress and Cell Cycle Group, Universitat Pompeu Fabra, 08003 Barcelona, Spain.
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11
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Vandermeulen C, O’Grady T, Wayet J, Galvan B, Maseko S, Cherkaoui M, Desbuleux A, Coppin G, Olivet J, Ben Ameur L, Kataoka K, Ogawa S, Hermine O, Marcais A, Thiry M, Mortreux F, Calderwood MA, Van Weyenbergh J, Peloponese JM, Charloteaux B, Van den Broeke A, Hill DE, Vidal M, Dequiedt F, Twizere JC. The HTLV-1 viral oncoproteins Tax and HBZ reprogram the cellular mRNA splicing landscape. PLoS Pathog 2021; 17:e1009919. [PMID: 34543356 PMCID: PMC8483338 DOI: 10.1371/journal.ppat.1009919] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Revised: 09/30/2021] [Accepted: 08/27/2021] [Indexed: 12/12/2022] Open
Abstract
Viral infections are known to hijack the transcription and translation of the host cell. However, the extent to which viral proteins coordinate these perturbations remains unclear. Here we used a model system, the human T-cell leukemia virus type 1 (HTLV-1), and systematically analyzed the transcriptome and interactome of key effectors oncoviral proteins Tax and HBZ. We showed that Tax and HBZ target distinct but also common transcription factors. Unexpectedly, we also uncovered a large set of interactions with RNA-binding proteins, including the U2 auxiliary factor large subunit (U2AF2), a key cellular regulator of pre-mRNA splicing. We discovered that Tax and HBZ perturb the splicing landscape by altering cassette exons in opposing manners, with Tax inducing exon inclusion while HBZ induces exon exclusion. Among Tax- and HBZ-dependent splicing changes, we identify events that are also altered in Adult T cell leukemia/lymphoma (ATLL) samples from two independent patient cohorts, and in well-known cancer census genes. Our interactome mapping approach, applicable to other viral oncogenes, has identified spliceosome perturbation as a novel mechanism coordinated by Tax and HBZ to reprogram the transcriptome. Tax and HBZ are two viral regulatory proteins encoded by the human T-cell leukemia virus type 1 (HTLV-1) via sense and antisense transcripts, respectively. Both proteins are known to drive oncogenic processes that culminate in a T-cell neoplasm, known as Adult T cell leukemia/lymphoma (ATLL). We measured the effects of Tax and HBZ on host gene expression pathway by analyzing the interactome with cellular transcriptional and post-transcriptional regulators, and the transcriptome and mRNA splicing of cell lines expressing either Tax or HBZ. We compared our results with data obtained from independent cohorts of Japanese and Afro-Caribbean patients, and identified common splicing changes that might represent clinically useful biomarkers for ATLL. Finally, we provide evidence that the viral protein Tax can reprogram initial steps of the T-cell transcriptome diversification by hijacking the U2AF complex, a key cellular regulator of pre-mRNA splicing.
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Affiliation(s)
- Charlotte Vandermeulen
- Laboratory of Viral Interactomes, GIGA Institute, University of Liege, Liege, Belgium
- Center for Cancer Systems Biology (CCSB), Dana-Farber Cancer Institute, Boston, Massachusetts, United States of America
- Laboratory of Gene Expression and Cancer, GIGA Institute, University of Liege, Liege, Belgium
| | - Tina O’Grady
- Laboratory of Gene Expression and Cancer, GIGA Institute, University of Liege, Liege, Belgium
| | - Jerome Wayet
- Unit of Animal Genomics, GIGA, Université de Liège (ULiège), Liège, Belgium
| | - Bartimee Galvan
- Laboratory of Gene Expression and Cancer, GIGA Institute, University of Liege, Liege, Belgium
| | - Sibusiso Maseko
- Laboratory of Viral Interactomes, GIGA Institute, University of Liege, Liege, Belgium
| | - Majid Cherkaoui
- Laboratory of Viral Interactomes, GIGA Institute, University of Liege, Liege, Belgium
| | - Alice Desbuleux
- Laboratory of Viral Interactomes, GIGA Institute, University of Liege, Liege, Belgium
- Center for Cancer Systems Biology (CCSB), Dana-Farber Cancer Institute, Boston, Massachusetts, United States of America
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts, United States of America
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, Massachusetts, United States of America
| | - Georges Coppin
- Laboratory of Viral Interactomes, GIGA Institute, University of Liege, Liege, Belgium
- Center for Cancer Systems Biology (CCSB), Dana-Farber Cancer Institute, Boston, Massachusetts, United States of America
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts, United States of America
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, Massachusetts, United States of America
| | - Julien Olivet
- Laboratory of Viral Interactomes, GIGA Institute, University of Liege, Liege, Belgium
- Center for Cancer Systems Biology (CCSB), Dana-Farber Cancer Institute, Boston, Massachusetts, United States of America
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts, United States of America
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, Massachusetts, United States of America
| | - Lamya Ben Ameur
- Laboratory of Biology and Modeling of the Cell, CNRS UMR 5239, INSERM U1210, University of Lyon, Lyon, France
| | - Keisuke Kataoka
- Department of Pathology and Tumor Biology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Seishi Ogawa
- Department of Pathology and Tumor Biology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Olivier Hermine
- Service Hématologie Adultes, Assistance Publique-Hôpitaux de Paris, Hôpital Necker Enfants Malades, Université de Paris, Laboratoire d’onco-hématologie, Institut Necker-Enfants Malades, INSERM U1151, Université de Paris, Paris, France
| | - Ambroise Marcais
- Service Hématologie Adultes, Assistance Publique-Hôpitaux de Paris, Hôpital Necker Enfants Malades, Université de Paris, Laboratoire d’onco-hématologie, Institut Necker-Enfants Malades, INSERM U1151, Université de Paris, Paris, France
| | - Marc Thiry
- Unit of Cell and Tissue Biology, GIGA Institute, University of Liege, Liege, Belgium
| | - Franck Mortreux
- Laboratory of Biology and Modeling of the Cell, CNRS UMR 5239, INSERM U1210, University of Lyon, Lyon, France
| | - Michael A. Calderwood
- Center for Cancer Systems Biology (CCSB), Dana-Farber Cancer Institute, Boston, Massachusetts, United States of America
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts, United States of America
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, Massachusetts, United States of America
| | - Johan Van Weyenbergh
- Laboratory of Clinical and Epidemiological Virology, Rega Institute for Medical Research, Department of Microbiology, Immunology and Transplantation, Catholic University of Leuven, Leuven, Belgium
| | | | - Benoit Charloteaux
- Center for Cancer Systems Biology (CCSB), Dana-Farber Cancer Institute, Boston, Massachusetts, United States of America
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts, United States of America
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, Massachusetts, United States of America
- Department of Human Genetics, CHU of Liege, University of Liege, Liege, Belgium
| | - Anne Van den Broeke
- Unit of Animal Genomics, GIGA, Université de Liège (ULiège), Liège, Belgium
- Laboratory of Experimental Hematology, Institut Jules Bordet, Université Libre de Bruxelles (ULB), Brussels, Belgium
- * E-mail: (AVdB); (DEH); (MV); (FD); (J-CT)
| | - David E. Hill
- Center for Cancer Systems Biology (CCSB), Dana-Farber Cancer Institute, Boston, Massachusetts, United States of America
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts, United States of America
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, Massachusetts, United States of America
- * E-mail: (AVdB); (DEH); (MV); (FD); (J-CT)
| | - Marc Vidal
- Center for Cancer Systems Biology (CCSB), Dana-Farber Cancer Institute, Boston, Massachusetts, United States of America
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts, United States of America
- * E-mail: (AVdB); (DEH); (MV); (FD); (J-CT)
| | - Franck Dequiedt
- Laboratory of Gene Expression and Cancer, GIGA Institute, University of Liege, Liege, Belgium
- * E-mail: (AVdB); (DEH); (MV); (FD); (J-CT)
| | - Jean-Claude Twizere
- Laboratory of Viral Interactomes, GIGA Institute, University of Liege, Liege, Belgium
- Center for Cancer Systems Biology (CCSB), Dana-Farber Cancer Institute, Boston, Massachusetts, United States of America
- * E-mail: (AVdB); (DEH); (MV); (FD); (J-CT)
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12
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Mol AA, Vogel M, Suess B. Inducible nuclear import by TetR aptamer-controlled 3' splice site selection. RNA (NEW YORK, N.Y.) 2021; 27:234-241. [PMID: 33148600 PMCID: PMC7812871 DOI: 10.1261/rna.077453.120] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Accepted: 10/20/2020] [Indexed: 06/11/2023]
Abstract
Correct cellular localization is essential for the function of many eukaryotic proteins and hence cell physiology. Here, we present a synthetic genetic device that allows the control of nuclear and cytosolic localization based on controlled alternative splicing in human cells. The device is based on the fact that an alternative 3' splice site is located within a TetR aptamer that in turn is positioned between the branch point and the canonical splice site. The novel splice site is only recognized when the TetR repressor is bound. Addition of doxycycline prevents TetR aptamer binding and leads to recognition of the canonical 3' splice site. It is thus possible to produce two independent splice isoforms. Since the terminal loop of the aptamer may be replaced with any sequence of choice, one of the two isoforms may be extended by the respective sequence of choice depending on the presence of doxycycline. In a proof-of-concept study, we fused a nuclear localization sequence to a cytosolic target protein, thus directing the protein into the nucleus. However, the system is not limited to the control of nuclear localization. In principle, any target sequence can be integrated into the aptamer, allowing not only the production of a variety of different isoforms on demand, but also to study the function of mislocalized proteins. Moreover, it also provides a valuable tool for investigating the mechanism of alternative splicing in human cells.
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Affiliation(s)
- Adam A Mol
- Department of Biology, Technical University of Darmstadt, D-64287 Darmstadt, Germany
| | - Marc Vogel
- Department of Biology, Technical University of Darmstadt, D-64287 Darmstadt, Germany
| | - Beatrix Suess
- Department of Biology, Technical University of Darmstadt, D-64287 Darmstadt, Germany
- Centre for Synthetic Biology, Technical University of Darmstadt, D-64287 Darmstadt, Germany
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13
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Warnasooriya C, Feeney CF, Laird KM, Ermolenko DN, Kielkopf CL. A splice site-sensing conformational switch in U2AF2 is modulated by U2AF1 and its recurrent myelodysplasia-associated mutation. Nucleic Acids Res 2020; 48:5695-5709. [PMID: 32343311 PMCID: PMC7261175 DOI: 10.1093/nar/gkaa293] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Revised: 04/09/2020] [Accepted: 04/17/2020] [Indexed: 02/02/2023] Open
Abstract
An essential heterodimer of the U2AF1 and U2AF2 pre-mRNA splicing factors nucleates spliceosome assembly at polypyrimidine (Py) signals preceding the major class of 3′ splice sites. U2AF1 frequently acquires an S34F-encoding mutation among patients with myelodysplastic syndromes (MDS). The influence of the U2AF1 subunit and its S34F mutation on the U2AF2 conformations remains unknown. Here, we employ single molecule Förster resonance energy transfer (FRET) to determine the influence of wild-type or S34F-substituted U2AF1 on the conformational dynamics of U2AF2 and its splice site RNA complexes. In the absence of RNA, the U2AF1 subunit stabilizes a high FRET value, which by structure-guided mutagenesis corresponds to a closed conformation of the tandem U2AF2 RNA recognition motifs (RRMs). When the U2AF heterodimer is bound to a strong, uridine-rich splice site, U2AF2 switches to a lower FRET value characteristic of an open, side-by-side arrangement of the RRMs. Remarkably, the U2AF heterodimer binds weak, uridine-poor Py tracts as a mixture of closed and open U2AF2 conformations, which are modulated by the S34F mutation. Shifts between open and closed U2AF2 may underlie U2AF1-dependent splicing of degenerate Py tracts and contribute to a subset of S34F-dysregulated splicing events in MDS patients.
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Affiliation(s)
- Chandani Warnasooriya
- Department of Biochemistry and Biophysics and Center for RNA Biology, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA
| | - Callen F Feeney
- Department of Biochemistry and Biophysics and Center for RNA Biology, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA
| | - Kholiswa M Laird
- Department of Biochemistry and Biophysics and Center for RNA Biology, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA
| | - Dmitri N Ermolenko
- Department of Biochemistry and Biophysics and Center for RNA Biology, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA
| | - Clara L Kielkopf
- Department of Biochemistry and Biophysics and Center for RNA Biology, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA
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14
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Chang JW, Yeh HS, Park M, Erber L, Sun J, Cheng S, Bui AM, Fahmi NA, Nasti R, Kuang R, Chen Y, Zhang W, Yong J. mTOR-regulated U2af1 tandem exon splicing specifies transcriptome features for translational control. Nucleic Acids Res 2019; 47:10373-10387. [PMID: 31504847 PMCID: PMC6821156 DOI: 10.1093/nar/gkz761] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Revised: 07/23/2019] [Accepted: 08/23/2019] [Indexed: 01/13/2023] Open
Abstract
U2 auxiliary factor 1 (U2AF1) functions in 3′-splice site selection during pre-mRNA processing. Alternative usage of duplicated tandem exons in U2AF1 produces two isoforms, U2AF1a and U2AF1b, but their functional differences are unappreciated due to their homology. Through integrative approaches of genome editing, customized-transcriptome profiling and crosslinking-mediated interactome analyses, we discovered that the expression of U2AF1 isoforms is controlled by mTOR and they exhibit a distinctive molecular profile for the splice site and protein interactomes. Mechanistic dissection of mutually exclusive alternative splicing events revealed that U2AF1 isoforms’ inherent differential preferences of nucleotide sequences and their stoichiometry determine the 3′-splice site. Importantly, U2AF1a-driven transcriptomes feature alternative splicing events in the 5′-untranslated region (5′-UTR) that are favorable for translation. These findings unveil distinct roles of duplicated tandem exon-derived U2AF1 isoforms in the regulation of the transcriptome and suggest U2AF1a-driven 5′-UTR alternative splicing as a molecular mechanism of mTOR-regulated translational control.
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Affiliation(s)
- Jae-Woong Chang
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota Twin Cities, Minneapolis, MN 55455, USA
| | - Hsin-Sung Yeh
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota Twin Cities, Minneapolis, MN 55455, USA
| | - Meeyeon Park
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota Twin Cities, Minneapolis, MN 55455, USA
| | - Luke Erber
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota Twin Cities, Minneapolis, MN 55455, USA
| | - Jiao Sun
- Department of Computer Science, University of Central Florida, Orlando, FL 32816, USA
| | - Sze Cheng
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota Twin Cities, Minneapolis, MN 55455, USA
| | - Alexander M Bui
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota Twin Cities, Minneapolis, MN 55455, USA
| | - Naima Ahmed Fahmi
- Department of Computer Science, University of Central Florida, Orlando, FL 32816, USA
| | - Ryan Nasti
- Department of Genetics, Cell and Developmental Biology, University of Minnesota Twin Cities, Minneapolis, MN 55455, USA
| | - Rui Kuang
- Department of Computer Science and Engineering, University of Minnesota Twin Cities, Minneapolis, MN 55455, USA
| | - Yue Chen
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota Twin Cities, Minneapolis, MN 55455, USA
| | - Wei Zhang
- Department of Computer Science, University of Central Florida, Orlando, FL 32816, USA
| | - Jeongsik Yong
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota Twin Cities, Minneapolis, MN 55455, USA
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15
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Xiong F, Ren JJ, Yu Q, Wang YY, Lu CC, Kong LJ, Otegui MS, Wang XL. AtU2AF65b functions in abscisic acid mediated flowering via regulating the precursor messenger RNA splicing of ABI5 and FLC in Arabidopsis. THE NEW PHYTOLOGIST 2019; 223:277-292. [PMID: 30790290 DOI: 10.1111/nph.15756] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Accepted: 02/11/2019] [Indexed: 05/20/2023]
Abstract
In mammalians and yeast, the splicing factor U2AF65/Mud2p functions in precursor messenger RNA (pre-mRNA) processing. Arabidopsis AtU2AF65b encodes a putative U2AF65 but its specific functions in plants are unknown. This paper examines the function of AtU2AF65b as a negative regulator of flowering time in Arabidopsis. We investigated the expression and function of AtU2AF65b in abscisic acid (ABA)-regulated flowering as well as the transcript abundance and pre-mRNA splicing of flowering-related genes in the knock-out mutants of AtU2AF65b. The atu2af65b mutants show early-flowering phenotype under both long-day and short-day conditions. The transcript accumulation of the flowering repressor gene FLOWERING LOCUS C (FLC) is reduced in the shoot apex of atu2af65b, due to both increased intron retention and reduced transcription activation. Reduced transcription of FLC results, at least partially, from the abnormal splicing and reduced transcript abundance of ABSCISIC ACID-INSENSITIVE 5 (ABI5), which encodes an activator of FLC in ABA-regulated flowering signaling. Additionally, the expression of AtU2AF65b is promoted by ABA. Transition to flowering and splicing of FLC and ABI5 in the atu2af65b mutants are compromised during ABA-induced flowering. ABA-responsive AtU2AF65b functions in the pre-mRNA splicing of FLC and ABI5 in shoot apex, whereby AtU2AF65b is involved in ABA-mediated flowering transition in Arabidopsis.
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Affiliation(s)
- Feng Xiong
- National Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Taian, 271018, China
| | - Jing-Jing Ren
- National Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Taian, 271018, China
| | - Qin Yu
- National Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Taian, 271018, China
| | - Yu-Yi Wang
- National Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Taian, 271018, China
| | - Chong-Chong Lu
- National Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Taian, 271018, China
| | - Lan-Jing Kong
- National Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Taian, 271018, China
| | - Marisa S Otegui
- Department of Botany and Genetics, University of Wisconsin-Madison, Madison, WI, 53706, USA
- Laboratory of Cell and Molecular Biology, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Xiu-Ling Wang
- National Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Taian, 271018, China
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16
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Loerch S, Leach JR, Horner SW, Maji D, Jenkins JL, Pulvino MJ, Kielkopf CL. The pre-mRNA splicing and transcription factor Tat-SF1 is a functional partner of the spliceosome SF3b1 subunit via a U2AF homology motif interface. J Biol Chem 2018; 294:2892-2902. [PMID: 30567737 DOI: 10.1074/jbc.ra118.006764] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Revised: 12/10/2018] [Indexed: 01/09/2023] Open
Abstract
The transcription elongation and pre-mRNA splicing factor Tat-SF1 associates with the U2 small nuclear ribonucleoprotein (snRNP) of the spliceosome. However, the direct binding partner and underlying interactions mediating the Tat-SF1-U2 snRNP association remain unknown. Here, we identified SF3b1 as a Tat-SF1-interacting subunit of the U2 snRNP. Our 1.1 Å resolution crystal structure revealed that Tat-SF1 contains a U2AF homology motif (UHM) protein-protein interaction module. We demonstrated that Tat-SF1 preferentially and directly binds the SF3b1 subunit compared with other U2AF ligand motif (ULM)-containing splicing factors, and further established that SF3b1 association depends on the integrity of the Tat-SF1 UHM. We next compared the Tat-SF1-binding affinities for each of the five known SF3b1 ULMs and then determined the structures of representative high- and low-affinity SF3b1 ULM complexes with the Tat-SF1 UHM at 1.9 Å and 2.1 Å resolutions, respectively. These structures revealed a canonical UHM-ULM interface, comprising a Tat-SF1 binding pocket for a ULM tryptophan (SF3b1 Trp338) and electrostatic interactions with a basic ULM tail. Importantly, we found that SF3b1 regulates Tat-SF1 levels and that these two factors influence expression of overlapping representative transcripts, consistent with a functional partnership of Tat-SF1 and SF3b1. Altogether, these results define a new molecular interface of the Tat-SF1-U2 snRNP complex for gene regulation.
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Affiliation(s)
- Sarah Loerch
- From the Center for RNA Biology, Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642
| | - Justin R Leach
- From the Center for RNA Biology, Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642
| | - Steven W Horner
- From the Center for RNA Biology, Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642
| | - Debanjana Maji
- From the Center for RNA Biology, Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642
| | - Jermaine L Jenkins
- From the Center for RNA Biology, Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642
| | - Mary J Pulvino
- From the Center for RNA Biology, Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642
| | - Clara L Kielkopf
- From the Center for RNA Biology, Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642
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17
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Sertznig H, Hillebrand F, Erkelenz S, Schaal H, Widera M. Behind the scenes of HIV-1 replication: Alternative splicing as the dependency factor on the quiet. Virology 2018; 516:176-188. [PMID: 29407375 DOI: 10.1016/j.virol.2018.01.011] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Revised: 01/10/2018] [Accepted: 01/11/2018] [Indexed: 01/31/2023]
Abstract
Alternative splicing plays a key role in the HIV-1 life cycle and is essential to maintain an equilibrium of mRNAs that encode viral proteins and polyprotein-isoforms. In particular, since all early HIV-1 proteins are expressed from spliced intronless and late enzymatic and structural proteins from intron containing, i.e. splicing repressed viral mRNAs, cellular splicing factors and splicing regulatory proteins are crucial for the replication capacity. In this review, we will describe the complex network of cis-acting splicing regulatory elements (SREs), which are mainly localized in the neighbourhoods of all HIV-1 splice sites and warrant the proper ratio of individual transcript isoforms. Since SREs represent binding sites for trans-acting cellular splicing factors interacting with the cellular spliceosomal apparatus we will review the current knowledge of interactions between viral RNA and cellular proteins as well as their impact on viral replication. Finally, we will discuss potential therapeutic approaches targeting HIV-1 alternative splicing.
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Affiliation(s)
- Helene Sertznig
- Institute for Virology, University Hospital Essen, University of Duisburg-Essen, Essen, Germany
| | - Frank Hillebrand
- Institute of Virology, Heinrich Heine University, University Hospital, Düsseldorf, Germany
| | - Steffen Erkelenz
- Institute for Genetics, Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Germany
| | - Heiner Schaal
- Institute of Virology, Heinrich Heine University, University Hospital, Düsseldorf, Germany
| | - Marek Widera
- Institute for Virology, University Hospital Essen, University of Duisburg-Essen, Essen, Germany.
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18
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Ohno K, Takeda JI, Masuda A. Rules and tools to predict the splicing effects of exonic and intronic mutations. WILEY INTERDISCIPLINARY REVIEWS-RNA 2017; 9. [DOI: 10.1002/wrna.1451] [Citation(s) in RCA: 71] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2017] [Revised: 08/23/2017] [Accepted: 08/24/2017] [Indexed: 12/14/2022]
Affiliation(s)
- Kinji Ohno
- Division of Neurogenetics, Center for Neurological Diseases and Cancer; Nagoya University Graduate School of Medicine; Nagoya Japan
| | - Jun-ichi Takeda
- Division of Neurogenetics, Center for Neurological Diseases and Cancer; Nagoya University Graduate School of Medicine; Nagoya Japan
| | - Akio Masuda
- Division of Neurogenetics, Center for Neurological Diseases and Cancer; Nagoya University Graduate School of Medicine; Nagoya Japan
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19
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Mutations of RNA splicing factors in hematological malignancies. Cancer Lett 2017; 409:1-8. [PMID: 28888996 DOI: 10.1016/j.canlet.2017.08.042] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Revised: 08/22/2017] [Accepted: 08/28/2017] [Indexed: 01/01/2023]
Abstract
Systematic large-scale cancer genomic studies have produced numerous significant findings. These studies have not only revealed new cancer-promoting genes, but they also have identified cancer-promoting functions of previously known "housekeeping" genes. These studies have identified numerous mutations in genes which play a fundamental role in nuclear precursor mRNA splicing. Somatic mutations and copy number variation in many of the splicing factors which participate in the formation of multiple spliceosomal complexes appear to play a role in many cancers and in particular in myelodysplastic syndromes (MDS). Mutated proteins seem to interfere with the recognition of the authentic splice sites (SS) leading to utilization of suboptimal alternative splicing sites generating aberrantly spliced mRNA isoforms. This short review is focusing on the function of the splice factors involved in the formation of splicing complexes and potential mechanisms which affect usage of the authentic splice site recognition.
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20
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Jenkins JL, Kielkopf CL. Splicing Factor Mutations in Myelodysplasias: Insights from Spliceosome Structures. Trends Genet 2017; 33:336-348. [PMID: 28372848 PMCID: PMC5447463 DOI: 10.1016/j.tig.2017.03.001] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Revised: 02/28/2017] [Accepted: 03/02/2017] [Indexed: 01/08/2023]
Abstract
Somatic mutations of pre-mRNA splicing factors recur among patients with myelodysplastic syndrome (MDS) and related malignancies. Although these MDS-relevant mutations alter the splicing of a subset of transcripts, the mechanisms by which these single amino acid substitutions change gene expression remain controversial. New structures of spliceosome intermediates and associated protein complexes shed light on the molecular interactions mediated by 'hotspots' of the SF3B1 and U2AF1 pre-mRNA splicing factors. The frequently mutated SF3B1 residues contact the pre-mRNA splice site. Based on structural homology with other spliceosome subunits, and recent findings of altered RNA binding by mutant U2AF1 proteins, we suggest that affected U2AF1 residues also contact pre-mRNA. Altered pre-mRNA recognition emerges as a molecular theme among MDS-relevant mutations of pre-mRNA splicing factors.
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Affiliation(s)
- Jermaine L Jenkins
- Center for RNA Biology and Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA
| | - Clara L Kielkopf
- Center for RNA Biology and Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA.
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21
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Sidarovich A, Will CL, Anokhina MM, Ceballos J, Sievers S, Agafonov DE, Samatov T, Bao P, Kastner B, Urlaub H, Waldmann H, Lührmann R. Identification of a small molecule inhibitor that stalls splicing at an early step of spliceosome activation. eLife 2017; 6. [PMID: 28300534 PMCID: PMC5354520 DOI: 10.7554/elife.23533] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Accepted: 02/26/2017] [Indexed: 11/13/2022] Open
Abstract
Small molecule inhibitors of pre-mRNA splicing are important tools for identifying new spliceosome assembly intermediates, allowing a finer dissection of spliceosome dynamics and function. Here, we identified a small molecule that inhibits human pre-mRNA splicing at an intermediate stage during conversion of pre-catalytic spliceosomal B complexes into activated Bact complexes. Characterization of the stalled complexes (designated B028) revealed that U4/U6 snRNP proteins are released during activation before the U6 Lsm and B-specific proteins, and before recruitment and/or stable incorporation of Prp19/CDC5L complex and other Bact complex proteins. The U2/U6 RNA network in B028 complexes differs from that of the Bact complex, consistent with the idea that the catalytic RNA core forms stepwise during the B to Bact transition and is likely stabilized by the Prp19/CDC5L complex and related proteins. Taken together, our data provide new insights into the RNP rearrangements and extensive exchange of proteins that occurs during spliceosome activation. DOI:http://dx.doi.org/10.7554/eLife.23533.001
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Affiliation(s)
- Anzhalika Sidarovich
- Department of Cellular Biochemistry, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Cindy L Will
- Department of Cellular Biochemistry, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Maria M Anokhina
- Department of Cellular Biochemistry, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Javier Ceballos
- Department of Chemical Biology, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Sonja Sievers
- Compound Management and Screening Center, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Dmitry E Agafonov
- Department of Cellular Biochemistry, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Timur Samatov
- Department of Cellular Biochemistry, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Penghui Bao
- Department of Cellular Biochemistry, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Berthold Kastner
- Department of Cellular Biochemistry, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Henning Urlaub
- Bioanalytics Group, Institute for Clinical Chemistry Göttingen, University Medical Center, Göttingen, Germany
| | - Herbert Waldmann
- Department of Chemical Biology, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Reinhard Lührmann
- Department of Cellular Biochemistry, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
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22
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Jagtap PKA, Garg D, Kapp TG, Will CL, Demmer O, Lührmann R, Kessler H, Sattler M. Rational Design of Cyclic Peptide Inhibitors of U2AF Homology Motif (UHM) Domains To Modulate Pre-mRNA Splicing. J Med Chem 2016; 59:10190-10197. [PMID: 27753493 DOI: 10.1021/acs.jmedchem.6b01118] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
U2AF homology motifs (UHMs) are atypical RNA recognition motif domains that mediate critical protein-protein interactions during the regulation of alternative pre-mRNA splicing and other processes. The recognition of UHM domains by UHM ligand motif (ULM) peptide sequences plays important roles during early steps of spliceosome assembly. Splicing factor 45 kDa (SPF45) is an alternative splicing factor implicated in breast and lung cancers, and splicing regulation of apoptosis-linked pre-mRNAs by SPF45 was shown to depend on interactions between its UHM domain and ULM motifs in constitutive splicing factors. We have developed cyclic peptide inhibitors that target UHM domains. By screening a focused library of linear and cyclic peptides and performing structure-activity relationship analysis, we designed cyclic peptides with 4-fold improved binding affinity for the SPF45 UHM domain compared to native ULM ligands and 270-fold selectivity to discriminate UHM domains from alternative and constitutive splicing factors. These inhibitors are useful tools to modulate and dissect mechanisms of alternative splicing regulation.
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Affiliation(s)
- Pravin Kumar Ankush Jagtap
- Institute of Structural Biology, Helmholtz Zentrum München , Ingolstaedter Landstrasse 1, 85764 Neuherberg, Germany.,Center for Integrated Protein Science Munich (CIPSM), Department Chemie, Technische Universität München , Lichtenbergstrasse 4, 85747 Garching, Germany
| | - Divita Garg
- Institute of Structural Biology, Helmholtz Zentrum München , Ingolstaedter Landstrasse 1, 85764 Neuherberg, Germany.,Center for Integrated Protein Science Munich (CIPSM), Department Chemie, Technische Universität München , Lichtenbergstrasse 4, 85747 Garching, Germany
| | - Tobias G Kapp
- Center for Integrated Protein Science Munich (CIPSM), Department Chemie, Technische Universität München , Lichtenbergstrasse 4, 85747 Garching, Germany.,Institute for Advanced Study (IAS), Technische Universität München , Lichtenbergstrasse 4, 85747 Garching, Germany
| | - Cindy L Will
- Max Planck Institute for Biophysical Chemistry , Department of Cellular Biochemistry, Am Fassberg 11, 37077 Göttingen, Germany
| | - Oliver Demmer
- Center for Integrated Protein Science Munich (CIPSM), Department Chemie, Technische Universität München , Lichtenbergstrasse 4, 85747 Garching, Germany.,Institute for Advanced Study (IAS), Technische Universität München , Lichtenbergstrasse 4, 85747 Garching, Germany
| | - Reinhard Lührmann
- Max Planck Institute for Biophysical Chemistry , Department of Cellular Biochemistry, Am Fassberg 11, 37077 Göttingen, Germany
| | - Horst Kessler
- Center for Integrated Protein Science Munich (CIPSM), Department Chemie, Technische Universität München , Lichtenbergstrasse 4, 85747 Garching, Germany.,Institute for Advanced Study (IAS), Technische Universität München , Lichtenbergstrasse 4, 85747 Garching, Germany
| | - Michael Sattler
- Institute of Structural Biology, Helmholtz Zentrum München , Ingolstaedter Landstrasse 1, 85764 Neuherberg, Germany.,Center for Integrated Protein Science Munich (CIPSM), Department Chemie, Technische Universität München , Lichtenbergstrasse 4, 85747 Garching, Germany
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23
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Recognition of the 3' splice site RNA by the U2AF heterodimer involves a dynamic population shift. Proc Natl Acad Sci U S A 2016; 113:E7169-E7175. [PMID: 27799531 DOI: 10.1073/pnas.1605873113] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
An essential early step in the assembly of human spliceosomes onto pre-mRNA involves the recognition of regulatory RNA cis elements in the 3' splice site by the U2 auxiliary factor (U2AF). The large (U2AF65) and small (U2AF35) subunits of the U2AF heterodimer contact the polypyrimidine tract (Py-tract) and the AG-dinucleotide, respectively. The tandem RNA recognition motif domains (RRM1,2) of U2AF65 adopt closed/inactive and open/active conformations in the free form and when bound to bona fide Py-tract RNA ligands. To investigate the molecular mechanism and dynamics of 3' splice site recognition by U2AF65 and the role of U2AF35 in the U2AF heterodimer, we have combined single-pair FRET and NMR experiments. In the absence of RNA, the RRM1,2 domain arrangement is highly dynamic on a submillisecond time scale, switching between closed and open conformations. The addition of Py-tract RNA ligands with increasing binding affinity (strength) gradually shifts the equilibrium toward an open conformation. Notably, the protein-RNA complex is rigid in the presence of a strong Py-tract but exhibits internal motion with weak Py-tracts. Surprisingly, the presence of U2AF35, whose UHM domain interacts with U2AF65 RRM1, increases the population of the open arrangement of U2AF65 RRM1,2 in the absence and presence of a weak Py-tract. These data indicate that the U2AF heterodimer promotes spliceosome assembly by a dynamic population shift toward the open conformation of U2AF65 to facilitate the recognition of weak Py-tracts at the 3' splice site. The structure and RNA binding of the heterodimer was unaffected by cancer-linked myelodysplastic syndrome mutants.
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24
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Stepanyuk GA, Serrano P, Peralta E, Farr CL, Axelrod HL, Geralt M, Das D, Chiu HJ, Jaroszewski L, Deacon AM, Lesley SA, Elsliger MA, Godzik A, Wilson IA, Wüthrich K, Salomon DR, Williamson JR. UHM-ULM interactions in the RBM39-U2AF65 splicing-factor complex. Acta Crystallogr D Struct Biol 2016; 72:497-511. [PMID: 27050129 PMCID: PMC4822562 DOI: 10.1107/s2059798316001248] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2016] [Accepted: 01/19/2016] [Indexed: 01/14/2023] Open
Abstract
RNA-binding protein 39 (RBM39) is a splicing factor and a transcriptional co-activator of estrogen receptors and Jun/AP-1, and its function has been associated with malignant progression in a number of cancers. The C-terminal RRM domain of RBM39 belongs to the U2AF homology motif family (UHM), which mediate protein-protein interactions through a short tryptophan-containing peptide known as the UHM-ligand motif (ULM). Here, crystal and solution NMR structures of the RBM39-UHM domain, and the crystal structure of its complex with U2AF65-ULM, are reported. The RBM39-U2AF65 interaction was confirmed by co-immunoprecipitation from human cell extracts, by isothermal titration calorimetry and by NMR chemical shift perturbation experiments with the purified proteins. When compared with related complexes, such as U2AF35-U2AF65 and RBM39-SF3b155, the RBM39-UHM-U2AF65-ULM complex reveals both common and discriminating recognition elements in the UHM-ULM binding interface, providing a rationale for the known specificity of UHM-ULM interactions. This study therefore establishes a structural basis for specific UHM-ULM interactions by splicing factors such as U2AF35, U2AF65, RBM39 and SF3b155, and a platform for continued studies of intermolecular interactions governing disease-related alternative splicing in eukaryotic cells.
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Affiliation(s)
- Galina A. Stepanyuk
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Pedro Serrano
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
- Joint Center for Structural Genomics, http://www.jcsg.org
| | - Eigen Peralta
- Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Carol L. Farr
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
- Joint Center for Structural Genomics, http://www.jcsg.org
- Protein Sciences Department, Genomics Institute of the Novartis Research Foundation, San Diego, CA 92121, USA
| | - Herbert L. Axelrod
- Joint Center for Structural Genomics, http://www.jcsg.org
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Michael Geralt
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
- Joint Center for Structural Genomics, http://www.jcsg.org
| | - Debanu Das
- Joint Center for Structural Genomics, http://www.jcsg.org
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Hsiu-Ju Chiu
- Joint Center for Structural Genomics, http://www.jcsg.org
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Lukasz Jaroszewski
- Joint Center for Structural Genomics, http://www.jcsg.org
- Program on Bioinformatics and Systems Biology, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA 92037, USA
- Center for Research in Biological Systems, University of California, San Diego, La Jolla, CA 92093-0446, USA
| | - Ashley M. Deacon
- Joint Center for Structural Genomics, http://www.jcsg.org
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Scott A. Lesley
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
- Joint Center for Structural Genomics, http://www.jcsg.org
- Protein Sciences Department, Genomics Institute of the Novartis Research Foundation, San Diego, CA 92121, USA
| | - Marc-André Elsliger
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
- Joint Center for Structural Genomics, http://www.jcsg.org
| | - Adam Godzik
- Joint Center for Structural Genomics, http://www.jcsg.org
- Program on Bioinformatics and Systems Biology, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA 92037, USA
- Center for Research in Biological Systems, University of California, San Diego, La Jolla, CA 92093-0446, USA
| | - Ian A. Wilson
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
- Joint Center for Structural Genomics, http://www.jcsg.org
- The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Kurt Wüthrich
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
- Joint Center for Structural Genomics, http://www.jcsg.org
- The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Daniel R. Salomon
- Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - James R. Williamson
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
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25
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Alsafadi S, Houy A, Battistella A, Popova T, Wassef M, Henry E, Tirode F, Constantinou A, Piperno-Neumann S, Roman-Roman S, Dutertre M, Stern MH. Cancer-associated SF3B1 mutations affect alternative splicing by promoting alternative branchpoint usage. Nat Commun 2016; 7:10615. [PMID: 26842708 DOI: 10.1038/ncomms10615] [Citation(s) in RCA: 272] [Impact Index Per Article: 34.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Accepted: 01/05/2016] [Indexed: 12/20/2022] Open
Abstract
Hotspot mutations in the spliceosome gene SF3B1 are reported in ∼20% of uveal melanomas. SF3B1 is involved in 3'-splice site (3'ss) recognition during RNA splicing; however, the molecular mechanisms of its mutation have remained unclear. Here we show, using RNA-Seq analyses of uveal melanoma, that the SF3B1(R625/K666) mutation results in deregulated splicing at a subset of junctions, mostly by the use of alternative 3'ss. Modelling the differential junctions in SF3B1(WT) and SF3B1(R625/K666) cell lines demonstrates that the deregulated splice pattern strictly depends on SF3B1 status and on the 3'ss-sequence context. SF3B1(WT) knockdown or overexpression do not reproduce the SF3B1(R625/K666) splice pattern, qualifying SF3B1(R625/K666) as change-of-function mutants. Mutagenesis of predicted branchpoints reveals that the SF3B1(R625/K666)-promoted splice pattern is a direct result of alternative branchpoint usage. Altogether, this study provides a better understanding of the mechanisms underlying splicing alterations induced by mutant SF3B1 in cancer, and reveals a role for alternative branchpoints in disease.
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Affiliation(s)
- Samar Alsafadi
- Department of Genetics and Biology of Cancers, INSERM U830, Institut Curie, PSL Research University, Paris 75248, France
| | - Alexandre Houy
- Department of Genetics and Biology of Cancers, INSERM U830, Institut Curie, PSL Research University, Paris 75248, France
| | - Aude Battistella
- Department of Genetics and Biology of Cancers, INSERM U830, Institut Curie, PSL Research University, Paris 75248, France
| | - Tatiana Popova
- Department of Genetics and Biology of Cancers, INSERM U830, Institut Curie, PSL Research University, Paris 75248, France
| | - Michel Wassef
- Depatment of Developmental Biology and Genetics, CNRS UMR 3215/INSERM U934, Institut Curie, PSL Research University, Paris 75248, France
| | - Emilie Henry
- Translational Research Department, Institut Curie, PSL Research University, Paris 75248, France
| | - Franck Tirode
- Department of Genetics and Biology of Cancers, INSERM U830, Institut Curie, PSL Research University, Paris 75248, France
| | - Angelos Constantinou
- Department of Molecular Bases of Human Diseases, CNRS UPR 1142, IGH-Institute of Human Genetics, Montpellier 34090, France
| | | | - Sergio Roman-Roman
- Translational Research Department, Institut Curie, PSL Research University, Paris 75248, France
| | - Martin Dutertre
- Department of Genotoxic stress and Cancer, CNRS UMR 3348, Institut Curie, PSL Research University, Orsay 91400, France
| | - Marc-Henri Stern
- Department of Genetics and Biology of Cancers, INSERM U830, Institut Curie, PSL Research University, Paris 75248, France
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26
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Abstract
The U2AF heterodimer is generally accepted to play a vital role in defining functional 3' splice sites in pre-mRNA splicing. Given prevalent mutations in U2AF, particularly in the U2AF1 gene (which encodes for the U2AF35 subunit) in blood disorders and other human cancers, there are renewed interests in these classic splicing factors to further understand their regulatory functions in RNA metabolism in both physiological and disease settings. We recently reported that U2AF has a maximal capacity to directly bind ˜88% of functional 3' splice sites in the human genome and that numerous U2AF binding events also occur in various exonic and intronic locations, thus providing additional mechanisms for the regulation of alternative splicing besides their traditional role in titrating weak splice sites in the cell. These findings, coupled with the existence of multiple related proteins to both U2AF65 and U2AF35, beg a series of questions on the universal role of U2AF in functional 3' splice site definition, their binding specificities in vivo, potential mechanisms to bypass their requirement for certain intron removal events, contribution of splicing-independent functions of U2AF to important cellular functions, and the mechanism for U2AF mutations to invoke specific diseases in humans.
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Affiliation(s)
- Tongbin Wu
- a Department of Medicine ; University of California, San Diego ; La Jolla , CA USA
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27
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Chiba M, Ariga H, Maita H. A Splicing Reporter Tuned to Non-AG Acceptor Sites Reveals that Luteolin Enhances the Recognition of Non-canonical Acceptor Sites. Chem Biol Drug Des 2015; 87:275-82. [PMID: 26348996 DOI: 10.1111/cbdd.12656] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2015] [Revised: 07/31/2015] [Accepted: 08/27/2015] [Indexed: 12/20/2022]
Abstract
Removal of an intron requires precise recognition of the splice donor and acceptor sites located at the 5' and 3' termini of introns. Although the roles of these sequences differ, mutations in both sites easily block normal splicing and produce an aberrant mRNA. For example, many splice-site mutations occur in patients with inherited diseases. Several approaches have been evaluated to restore expression of a functional protein; however, because of the strict requirement for an AG dinucleotide at the 3' terminus of a U2-type intron, no method is available to correct splicing at a mutated sequence. To identify compounds that allow splicing at the non-AG acceptor site, in the present study we constructed a reporter gene with a modified polypyrimidine tract. However, the modified polypyrimidine tract mediated splicing at adjacent non-canonical acceptor sites, including the original mutated site. Further, we show that certain flavones such as luteolin and apigenin enhanced aberrant splicing at the non-canonical acceptor site of the reporter gene. These results suggest that the reporter gene and luteolin may be useful for further screening to identify molecules that correct aberrant splicing caused by a disease-associated splice acceptor site mutation.
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Affiliation(s)
- Masanori Chiba
- Graduate School of Life Science, Hokkaido University, Sapporo, 060-0812, Japan
| | - Hiroyoshi Ariga
- Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo, 060-0812, Japan
| | - Hiroshi Maita
- Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo, 060-0812, Japan
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28
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Crisci A, Raleff F, Bagdiul I, Raabe M, Urlaub H, Rain JC, Krämer A. Mammalian splicing factor SF1 interacts with SURP domains of U2 snRNP-associated proteins. Nucleic Acids Res 2015; 43:10456-73. [PMID: 26420826 PMCID: PMC4666396 DOI: 10.1093/nar/gkv952] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2015] [Accepted: 09/10/2015] [Indexed: 02/03/2023] Open
Abstract
Splicing factor 1 (SF1) recognizes the branch point sequence (BPS) at the 3′ splice site during the formation of early complex E, thereby pre-bulging the BPS adenosine, thought to facilitate subsequent base-pairing of the U2 snRNA with the BPS. The 65-kDa subunit of U2 snRNP auxiliary factor (U2AF65) interacts with SF1 and was shown to recruit the U2 snRNP to the spliceosome. Co-immunoprecipitation experiments of SF1-interacting proteins from HeLa cell extracts shown here are consistent with the presence of SF1 in early splicing complexes. Surprisingly almost all U2 snRNP proteins were found associated with SF1. Yeast two-hybrid screens identified two SURP domain-containing U2 snRNP proteins as partners of SF1. A short, evolutionarily conserved region of SF1 interacts with the SURP domains, stressing their role in protein–protein interactions. A reduction of A complex formation in SF1-depleted extracts could be rescued with recombinant SF1 containing the SURP-interaction domain, but only partial rescue was observed with SF1 lacking this sequence. Thus, SF1 can initially recruit the U2 snRNP to the spliceosome during E complex formation, whereas U2AF65 may stabilize the association of the U2 snRNP with the spliceosome at later times. In addition, these findings may have implications for alternative splicing decisions.
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Affiliation(s)
- Angela Crisci
- Department of Cell Biology, Faculty of Sciences, University of Geneva, CH-1211 Geneva 4, Switzerland
| | - Flore Raleff
- Department of Cell Biology, Faculty of Sciences, University of Geneva, CH-1211 Geneva 4, Switzerland
| | - Ivona Bagdiul
- Department of Cell Biology, Faculty of Sciences, University of Geneva, CH-1211 Geneva 4, Switzerland
| | - Monika Raabe
- Bioanalytical Mass Spectrometry, Max Planck Institute for Biophysical Chemistry, D-37077 Göttingen, Germany
| | - Henning Urlaub
- Bioanalytical Mass Spectrometry, Max Planck Institute for Biophysical Chemistry, D-37077 Göttingen, Germany Bioanalytics, Institute for Clinical Chemistry, University Medical Center Göttingen, D-37075 Göttingen, Germany
| | | | - Angela Krämer
- Department of Cell Biology, Faculty of Sciences, University of Geneva, CH-1211 Geneva 4, Switzerland
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29
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Abstract
The human spliceosome is a large ribonucleoprotein complex that catalyzes pre-mRNA splicing. It consists of five snRNAs and more than 200 proteins. Because of this complexity, much work has focused on the Saccharomyces cerevisiae spliceosome, viewed as a highly simplified system with fewer than half as many splicing factors as humans. Nevertheless, it has been difficult to ascribe a mechanistic function to individual splicing factors or even to discern which are critical for catalyzing the splicing reaction. We have identified and characterized the splicing machinery from the red alga Cyanidioschyzon merolae, which has been reported to harbor only 26 intron-containing genes. The U2, U4, U5, and U6 snRNAs contain expected conserved sequences and have the ability to adopt secondary structures and form intermolecular base-pairing interactions, as in other organisms. C. merolae has a highly reduced set of 43 identifiable core splicing proteins, compared with ∼90 in budding yeast and ∼140 in humans. Strikingly, we have been unable to find a U1 snRNA candidate or any predicted U1-associated proteins, suggesting that splicing in C. merolae may occur without the U1 small nuclear ribonucleoprotein particle. In addition, based on mapping the identified proteins onto the known splicing cycle, we propose that there is far less compositional variability during splicing in C. merolae than in other organisms. The observed reduction in splicing factors is consistent with the elimination of spliceosomal components that play a peripheral or modulatory role in splicing, presumably retaining those with a more central role in organization and catalysis.
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30
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Structure-guided U2AF65 variant improves recognition and splicing of a defective pre-mRNA. Proc Natl Acad Sci U S A 2014; 111:17420-5. [PMID: 25422459 DOI: 10.1073/pnas.1412743111] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Purine interruptions of polypyrimidine (Py) tract splice site signals contribute to human genetic diseases. The essential splicing factor U2AF(65) normally recognizes a Py tract consensus sequence preceding the major class of 3' splice sites. We found that neurofibromatosis- or retinitis pigmentosa-causing mutations in the 5' regions of Py tracts severely reduce U2AF(65) affinity. Conversely, we identified a preferred binding site of U2AF(65) for purine substitutions in the 3' regions of Py tracts. Based on a comparison of new U2AF(65) structures bound to either A- or G-containing Py tracts with previously identified pyrimidine-containing structures, we expected to find that a D231V amino acid change in U2AF(65) would specify U over other nucleotides. We found that the crystal structure of the U2AF(65)-D231V variant confirms favorable packing between the engineered valine and a target uracil base. The D231V amino acid change restores U2AF(65) affinity for two mutated splice sites that cause human genetic diseases and successfully promotes splicing of a defective retinitis pigmentosa-causing transcript. We conclude that reduced U2AF(65) binding is a molecular consequence of disease-relevant mutations, and that a structure-guided U2AF(65) variant is capable of manipulating gene expression in eukaryotic cells.
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U2AF1 mutations alter sequence specificity of pre-mRNA binding and splicing. Leukemia 2014; 29:909-17. [PMID: 25311244 PMCID: PMC4391984 DOI: 10.1038/leu.2014.303] [Citation(s) in RCA: 90] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2014] [Revised: 09/24/2014] [Accepted: 10/07/2014] [Indexed: 01/04/2023]
Abstract
We previously identified missense mutations in the U2AF1 splicing factor affecting codons S34 (S34F and S34Y) or Q157 (Q157R and Q157P) in 11% of patients with de novo myelodysplastic syndromes (MDS). Although the role of U2AF1 as an accessory factor in the U2 snRNP is well established, it is not yet clear how mutations affect splicing or contribute to MDS pathophysiology. We analyzed splice junctions in RNA-seq data generated from transfected CD34+ hematopoietic cells and found significant differences in the abundance of known and novel junctions in samples expressing mutant U2AF1 (S34F). For selected transcripts, splicing alterations detected by RNA-seq were confirmed by analysis of primary de novo MDS patient samples. These effects were not due to impaired U2AF1 (S34F) localization as it co-localized normally with U2AF2 within nuclear speckles. We further found evidence in the RNA-seq data for decreased affinity of U2AF1 (S34F) for uridine (relative to cytidine) at the e-3 position immediately upstream of the splice acceptor site and corroborated this finding using affinity binding assays. These data suggest that the S34F mutation alters U2AF1 function in the context of specific RNA sequences, leading to aberrant alternative splicing of target genes, some of which may be relevant for MDS pathogenesis.
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A global regulatory mechanism for activating an exon network required for neurogenesis. Mol Cell 2014; 56:90-103. [PMID: 25219497 DOI: 10.1016/j.molcel.2014.08.011] [Citation(s) in RCA: 96] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Revised: 06/27/2014] [Accepted: 08/07/2014] [Indexed: 12/15/2022]
Abstract
The vertebrate and neural-specific Ser/Arg (SR)-related protein nSR100/SRRM4 regulates an extensive program of alternative splicing with critical roles in nervous system development. However, the mechanism by which nSR100 controls its target exons is poorly understood. We demonstrate that nSR100-dependent neural exons are associated with a unique configuration of intronic cis-elements that promote rapid switch-like regulation during neurogenesis. A key feature of this configuration is the insertion of specialized intronic enhancers between polypyrimidine tracts and acceptor sites that bind nSR100 to potently activate exon inclusion in neural cells while weakening 3' splice site recognition and contributing to exon skipping in nonneural cells. nSR100 further operates by forming multiple interactions with early spliceosome components bound proximal to 3' splice sites. These multifaceted interactions achieve dominance over neural exon silencing mediated by the splicing regulator PTBP1. The results thus illuminate a widespread mechanism by which a critical neural exon network is activated during neurogenesis.
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Grodecká L, Lockerová P, Ravčuková B, Buratti E, Baralle FE, Dušek L, Freiberger T. Exon first nucleotide mutations in splicing: evaluation of in silico prediction tools. PLoS One 2014; 9:e89570. [PMID: 24586880 PMCID: PMC3931810 DOI: 10.1371/journal.pone.0089570] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2013] [Accepted: 01/21/2014] [Indexed: 12/20/2022] Open
Abstract
Mutations in the first nucleotide of exons (E+1) mostly affect pre-mRNA splicing when found in AG-dependent 3′ splice sites, whereas AG-independent splice sites are more resistant. The AG-dependency, however, may be difficult to assess just from primary sequence data as it depends on the quality of the polypyrimidine tract. For this reason, in silico prediction tools are commonly used to score 3′ splice sites. In this study, we have assessed the ability of sequence features and in silico prediction tools to discriminate between the splicing-affecting and non-affecting E+1 variants. For this purpose, we newly tested 16 substitutions in vitro and derived other variants from literature. Surprisingly, we found that in the presence of the substituting nucleotide, the quality of the polypyrimidine tract alone was not conclusive about its splicing fate. Rather, it was the identity of the substituting nucleotide that markedly influenced it. Among the computational tools tested, the best performance was achieved using the Maximum Entropy Model and Position-Specific Scoring Matrix. As a result of this study, we have now established preliminary discriminative cut-off values showing sensitivity up to 95% and specificity up to 90%. This is expected to improve our ability to detect splicing-affecting variants in a clinical genetic setting.
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Affiliation(s)
- Lucie Grodecká
- Molecular Genetics Laboratory, Centre for Cardiovascular Surgery and Transplantation, Brno, Czech Republic
- Central European Institute of Technology, Masaryk University, Brno, Czech Republic
| | - Pavla Lockerová
- Molecular Genetics Laboratory, Centre for Cardiovascular Surgery and Transplantation, Brno, Czech Republic
| | - Barbora Ravčuková
- Molecular Genetics Laboratory, Centre for Cardiovascular Surgery and Transplantation, Brno, Czech Republic
| | - Emanuele Buratti
- International Centre for Genetic Engineering and Biotechnology, Trieste, Italy
| | | | - Ladislav Dušek
- Institute of Biostatistics and Analyses, Masaryk University, Brno, Czech Republic
| | - Tomáš Freiberger
- Molecular Genetics Laboratory, Centre for Cardiovascular Surgery and Transplantation, Brno, Czech Republic
- Central European Institute of Technology, Masaryk University, Brno, Czech Republic
- Institute of Clinical Immunology and Allergology, St. Anne’s University Hospital and Masaryk University, Brno, Czech Republic
- * E-mail:
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Yoshida K, Ogawa S. Splicing factor mutations and cancer. WILEY INTERDISCIPLINARY REVIEWS-RNA 2014; 5:445-59. [PMID: 24523246 DOI: 10.1002/wrna.1222] [Citation(s) in RCA: 114] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2013] [Revised: 01/09/2014] [Accepted: 01/13/2014] [Indexed: 12/11/2022]
Abstract
Recent advances in high-throughput sequencing technologies have unexpectedly revealed that somatic mutations of splicing factor genes frequently occurred in several types of hematological malignancies, including myelodysplastic syndromes, other myeloid neoplasms, and chronic lymphocytic leukemia. Splicing factor mutations have also been reported in solid cancers such as breast and pancreatic cancers, uveal melanomas, and lung adenocarcinomas. These mutations were heterozygous and mainly affected U2AF1 (U2AF35), SRSF2 (SC35), SF3B1 (SF3B155 or SAP155), and ZRSR2 (URP), which are engaged in the initial steps of RNA splicing, including 3' splice-site recognition, and occur in a large mutually exclusive pattern, suggesting a common impact of these mutations on RNA splicing. In this study, splicing factor mutations in various types of cancers, their functional/biological effects, and their potential as therapeutic targets have been reviewed.
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Affiliation(s)
- Kenichi Yoshida
- Department of Pathology and Tumor Biology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
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Martin RM, Rino J, Carvalho C, Kirchhausen T, Carmo-Fonseca M. Live-cell visualization of pre-mRNA splicing with single-molecule sensitivity. Cell Rep 2013; 4:1144-55. [PMID: 24035393 DOI: 10.1016/j.celrep.2013.08.013] [Citation(s) in RCA: 95] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2012] [Revised: 05/20/2013] [Accepted: 08/07/2013] [Indexed: 10/26/2022] Open
Abstract
Removal of introns from pre-messenger RNAs (pre-mRNAs) via splicing provides a versatile means of genetic regulation that is often disrupted in human diseases. To decipher how splicing occurs in real time, we directly examined with single-molecule sensitivity the kinetics of intron excision from pre-mRNA in the nucleus of living human cells. By using two different RNA labeling methods, MS2 and λN, we show that β-globin introns are transcribed and excised in 20-30 s. Furthermore, we show that replacing the weak polypyrimidine (Py) tract in mouse immunoglobulin μ (IgM) pre-mRNA by a U-rich Py decreases the intron lifetime, thus providing direct evidence that splice-site strength influences splicing kinetics. We also found that RNA polymerase II transcribes at elongation rates ranging between 3 and 6 kb min(-1) and that transcription can be rate limiting for splicing. These results have important implications for a mechanistic understanding of cotranscriptional splicing regulation in the live-cell context.
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Affiliation(s)
- Robert M Martin
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisboa, Portugal
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36
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Barman-Aksözen J, Béguin C, Dogar AM, Schneider-Yin X, Minder EI. Iron availability modulates aberrant splicing of ferrochelatase through the iron- and 2-oxoglutarate dependent dioxygenase Jmjd6 and U2AF(65.). Blood Cells Mol Dis 2013; 51:151-61. [PMID: 23787363 DOI: 10.1016/j.bcmd.2013.05.008] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2012] [Revised: 03/20/2013] [Accepted: 05/12/2013] [Indexed: 10/26/2022]
Abstract
Erythropoietic protoporphyria (EPP) results from partial deficiency of ferrochelatase (FECH). Genetically, EPP patients differ from asymptomatic mutation carriers at the unmutated FECH allele, the expression of which is modulated by single nucleotide polymorphism IVS3-48C/T. The IVS3-48C genotype, which is present among patients, leads to correct splicing of 60% of the pre-mRNA and to alternative splicing of 40%, the latter mRNA-product being destroyed by nonsense-mediated decay. An IVS3-48T genotype generates 80% correct and 20% aberrant products. Our study demonstrated that under iron deficient conditions, the aberrant splice product was increased to 56% and 50% of total FECH mRNA in erythroleukemic K562 and lymphoblastoid cell lines, respectively, both being homozygous for IVS3-48T. Concomitantly, FECH protein was decreased. Iron deficiency had less effect on the FECH splice ratio in an IVS3-48C/C lymphoblastoid cell line. Effects similar to iron deficiency were generated by siRNA knockdown of either splicing factor U2AF(65) or Fe(II)- and 2-oxoglutarate-dependent dioxygenase Jumonji domain-containing protein 6 (Jmjd6), which interacts with U2AF(65) by lysyl-hydroxylation. Based on these results, we propose that the availability of iron, a co-factor of Jmjd6, modulates U2AF(65)-lysyl-hydroxylation. This in turn, influences the relative amounts of correct and aberrant FECH mRNA splice products and thus, regulates the FECH enzyme activity.
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Sibley CR, Seow Y, Curtis H, Weinberg MS, Wood MJA. Silencing of Parkinson's disease-associated genes with artificial mirtron mimics of miR-1224. Nucleic Acids Res 2012; 40:9863-75. [PMID: 22848108 PMCID: PMC3479180 DOI: 10.1093/nar/gks712] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Mirtrons are a recently described category of microRNA (miRNA) relying on splicing rather than processing by the microprocessor complex to generate pre-miRNA precursors of the RNA interference (RNAi) pathway. Their discovery and subsequent verification provides important information about a distinct class of miRNA and inherent advantages that could be exploited to silence genes of interest. These include micro-processor-independent biogenesis, pol-II-dependent transcription, accurate species generation and the delivery of multiple artificial mirtrons as introns within a single host transcript. Here we determined the sequence motifs required for correct processing of the mmu-miR-1224 mirtron and incorporated these into artificial mirtrons targeting Parkinson's disease-associated LRRK2 and α-synuclein genes. By incorporating these rules associated with processing and splicing, artificial mirtrons could be designed and made to silence complementary targets either at the mRNA or protein level. We further demonstrate with a LRRK2 targeting artificial mirtron that neuronal-specific silencing can be directed under the control of the human synapsin promoter. Finally, multiple mirtrons were co-delivered within a single host transcript, an eGFP reporter, to allow simultaneous targeting of two or more targets in a combinatorial approach. Thus, the unique characteristics of artificial mirtrons make this an attractive approach for future RNAi applications.
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Affiliation(s)
- Christopher R Sibley
- Department of Physiology, Anatomy and Genetics, University of Oxford, South Parks Road, Oxford OX1 3QX, UK
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Curtis HJ, Sibley CR, Wood MJA. Mirtrons, an emerging class of atypical miRNA. WILEY INTERDISCIPLINARY REVIEWS-RNA 2012; 3:617-32. [PMID: 22733569 DOI: 10.1002/wrna.1122] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Post-transcriptional gene silencing (PTGS) via RNA interference (RNAi) is a vital gene regulatory mechanism for fine-tuning gene expression. RNAi effectors termed microRNAs (miRNAs) are implicated in various aspects of animal development and normal physiological function, while dysregulation has been linked to several pathologies. Several atypical miRNA biogenesis pathways have been identified, yet in most cases the reasons for their emergence remain unclear. One of these atypical pathways is the mirtron pathway, where short introns are excised by splicing to generate intermediates of the RNAi pathway, with no cleavage by the microprocessor. Closely related pathways involving tailed-mirtron and simtron biogenesis have also been described. There is extensive evidence that mirtrons function as miRNAs, and while some are evolutionarily conserved across similar species, others appear to have emerged relatively recently. In addition, through exploitation of the potent and sequence-specific silencing capabilities of RNAi, synthetic mirtrons may have potential for overcoming certain therapeutic challenges.
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Affiliation(s)
- Helen J Curtis
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
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Fu Y, Masuda A, Ito M, Shinmi J, Ohno K. AG-dependent 3'-splice sites are predisposed to aberrant splicing due to a mutation at the first nucleotide of an exon. Nucleic Acids Res 2011; 39:4396-404. [PMID: 21288883 PMCID: PMC3105431 DOI: 10.1093/nar/gkr026] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
In pre-mRNA splicing, a conserved AG/G at the 3′-splice site is recognized by U2AF35. A disease-causing mutation abrogating the G nucleotide at the first position of an exon (E+1) causes exon skipping in GH1, FECH and EYA1, but not in LPL or HEXA. Knockdown of U2AF35 enhanced exon skipping in GH1 and FECH. RNA-EMSA revealed that wild-type FECH requires U2AF35 but wild-type LPL does not. A series of artificial mutations in the polypyrimidine tracts of GH1, FECH, EYA1, LPL and HEXA disclosed that a stretch of at least 10–15 pyrimidines is required to ensure normal splicing in the presence of a mutation at E+1. Analysis of nine other disease-causing mutations at E+1 detected five splicing mutations. Our studies suggest that a mutation at the AG-dependent 3′-splice site that requires U2AF35 for spliceosome assembly causes exon skipping, whereas one at the AG-independent 3′-splice site that does not require U2AF35 gives rise to normal splicing. The AG-dependence of the 3′-splice site that we analyzed in disease-causing mutations at E+1 potentially helps identify yet unrecognized splicing mutations at E+1.
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Affiliation(s)
- Yuan Fu
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, 65 Tsurumai, Showa-ku, Nagoya 466-8550, Japan
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Allele-specific recognition of the 3' splice site of INS intron 1. Hum Genet 2010; 128:383-400. [PMID: 20628762 PMCID: PMC2939332 DOI: 10.1007/s00439-010-0860-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2010] [Accepted: 06/30/2010] [Indexed: 10/27/2022]
Abstract
Genetic predisposition to type 1 diabetes (T1D) has been associated with a chromosome 11 locus centered on the proinsulin gene (INS) and with differential steady-state levels of INS RNA from T1D-predisposing and -protective haplotypes. Here, we show that the haplotype-specific expression is determined by INS variants that control the splicing efficiency of intron 1. The adenine allele at IVS1-6 (rs689), which rapidly expanded in modern humans, renders the 3' splice site of this intron more dependent on the auxiliary factor of U2 small nuclear ribonucleoprotein (U2AF). This interaction required both zinc fingers of the 35-kD U2AF subunit (U2AF35) and was associated with repression of a competing 3' splice site in INS exon 2. Systematic mutagenesis of reporter constructs showed that intron 1 removal was facilitated by conserved guanosine-rich enhancers and identified additional splicing regulatory motifs in exon 2. Sequencing of intron 1 in primates revealed that relaxation of its 3' splice site in Hominidae coevolved with the introduction of a short upstream open reading frame, providing a more efficient coupled splicing and translation control. Depletion of SR proteins 9G8 and transformer-2 by RNA interference was associated with exon 2 skipping whereas depletion of SRp20 with increased representation of transcripts containing a cryptic 3' splice site in the last exon. Together, these findings reveal critical interactions underlying the allele-dependent INS expression and INS-mediated risk of T1D and suggest that the increased requirement for U2AF35 in higher primates may hinder thymic presentation of autoantigens encoded by transcripts with weak 3' splice sites.
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Martins de Araújo M, Bonnal S, Hastings ML, Krainer AR, Valcárcel J. Differential 3' splice site recognition of SMN1 and SMN2 transcripts by U2AF and U2 snRNP. RNA (NEW YORK, N.Y.) 2009; 15:515-23. [PMID: 19244360 PMCID: PMC2661831 DOI: 10.1261/rna.1273209] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2008] [Accepted: 01/14/2009] [Indexed: 05/20/2023]
Abstract
Spinal Muscular atrophy is a prevalent genetic disease caused by mutation of the SMN1 gene, which encodes the SMN protein involved in assembly of small nuclear ribonucleoprotein (snRNP) complexes. A paralog of the gene, SMN2, cannot provide adequate levels of functional SMN because exon 7 is skipped in a significant fraction of the mature transcripts. A C to T transition located at position 6 of exon 7 is critical for the difference in exon skipping between SMN1 and SMN2. Here we report that this nucleotide difference results in increased ultraviolet light-mediated crosslinking of the splicing factor U2AF(65) with the 3' splice site of SMN1 intron 6 in HeLa nuclear extract. U2 snRNP association, analyzed by native gel electrophoresis, is also more efficient on SMN1 than on SMN2, particularly under conditions of competition, suggesting more effective use of limiting factors. Two trans-acting factors implicated in SMN regulation, SF2/ASF and hnRNP A1, promote and repress, respectively, U2 snRNP recruitment to both RNAs. Interestingly, depending on the transcript and the regulatory factor, the effects on U2 binding not always correlate with changes in U2AF(65) crosslinking. Furthermore, blocking recognition of a Tra2-beta1-dependent splicing enhancer located in exon 7 inhibits U2 snRNP recruitment without affecting U2AF(65) crosslinking. Collectively, the results suggest that both U2AF binding and other steps of U2 snRNP recruitment can be control points in SMN splicing regulation.
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Brock JE, Dietrich RC, Padgett RA. Mutational analysis of the U12-dependent branch site consensus sequence. RNA (NEW YORK, N.Y.) 2008; 14:2430-2439. [PMID: 18824513 PMCID: PMC2578861 DOI: 10.1261/rna.1189008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2008] [Accepted: 08/01/2008] [Indexed: 05/26/2023]
Abstract
Highly conserved sequences at the 5' splice site and branch site of U12-dependent introns are important determinants for splicing by U12-dependent spliceosomes. This study investigates the in vivo splicing phenotypes of mutations in the branch site consensus sequence of the U12-dependent intron F from a human NOL1 (P120) minigene. Intron F contains a fully consensus branch site sequence (UUCCUUAAC). Mutations at each position were analyzed for their effects on U12-dependent splicing in vivo. Mutations at most positions resulted in a significant reduction of correct U12-dependent splicing. Defects observed included increased unspliced RNA levels, the activation of cryptic U2-dependent 5' and 3' splice sites, and the activation of cryptic U12-dependent branch/3' splice sites. A strong correlation was observed between the predicted thermodynamic stability of the branch site: U12 snRNA interaction and correct U12-dependent splicing. The lack of a polypyrimidine tract between the branch site and 3' splice site of U12-dependent introns and the observed reliance on base-pairing interactions for correct U12-dependent splicing emphasize the importance of RNA/RNA interactions during U12-dependent intron recognition and proper splice site selection.
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Affiliation(s)
- Jay E Brock
- Department of Molecular Genetics, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, Ohio 44195, USA
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Shaw SD, Chakrabarti S, Ghosh G, Krainer AR. Deletion of the N-terminus of SF2/ASF permits RS-domain-independent pre-mRNA splicing. PLoS One 2007; 2:e854. [PMID: 17786225 PMCID: PMC1952110 DOI: 10.1371/journal.pone.0000854] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2007] [Accepted: 08/13/2007] [Indexed: 01/01/2023] Open
Abstract
Serine/arginine-rich (SR) proteins are essential splicing factors with one or two RNA-recognition motifs (RRMs) and a C-terminal arginine- and serine-rich (RS) domain. SR proteins bind to exonic splicing enhancers via their RRM(s), and from this position are thought to promote splicing by antagonizing splicing silencers, recruiting other components of the splicing machinery through RS-RS domain interactions, and/or promoting RNA base-pairing through their RS domains. An RS domain tethered at an exonic splicing enhancer can function as a splicing activator, and RS domains play prominent roles in current models of SR protein functions. However, we previously reported that the RS domain of the SR protein SF2/ASF is dispensable for in vitro splicing of some pre-mRNAs. We have now extended these findings via the identification of a short inhibitory domain at the SF2/ASF N-terminus; deletion of this segment permits splicing in the absence of this SR protein's RS domain of an IgM pre-mRNA substrate previously classified as RS-domain-dependent. Deletion of the N-terminal inhibitory domain increases the splicing activity of SF2/ASF lacking its RS domain, and enhances its ability to bind pre-mRNA. Splicing of the IgM pre-mRNA in S100 complementation with SF2/ASF lacking its RS domain still requires an exonic splicing enhancer, suggesting that an SR protein RS domain is not always required for ESE-dependent splicing activation. Our data provide additional evidence that the SF2/ASF RS domain is not strictly required for constitutive splicing in vitro, contrary to prevailing models for how the domains of SR proteins function to promote splicing.
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Affiliation(s)
- Stephanie D. Shaw
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, United States of America
- Molecular and Cellular Biology Program, State University of New York at Stony Brook, Stony Brook, New York, United States of America
| | - Sutapa Chakrabarti
- Department of Chemistry and Biochemistry, University of California at San Diego, La Jolla, California, United States of America
| | - Gourisankar Ghosh
- Department of Chemistry and Biochemistry, University of California at San Diego, La Jolla, California, United States of America
| | - Adrian R. Krainer
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, United States of America
- * To whom correspondence should be addressed. E-mail:
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Abstract
U2 snRNP auxiliary factor (U2AF) is an essential heterodimeric splicing factor composed of two subunits, U2AF(65) and U2AF(35). During the past few years, a number of proteins related to both U2AF(65) and U2AF(35) have been discovered. Here, we review the conserved structural features that characterize the U2AF protein families and their evolutionary emergence. We perform a comprehensive database search designed to identify U2AF protein isoforms produced by alternative splicing, and we discuss the potential implications of U2AF protein diversity for splicing regulation.
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Affiliation(s)
- Inês Mollet
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Avenue Prof. Egas Moniz, 1649-028 Lisbon, Portugal
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Pacheco TR, Coelho MB, Desterro JMP, Mollet I, Carmo-Fonseca M. In vivo requirement of the small subunit of U2AF for recognition of a weak 3' splice site. Mol Cell Biol 2006; 26:8183-90. [PMID: 16940179 PMCID: PMC1636752 DOI: 10.1128/mcb.00350-06] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The U2 snRNP auxiliary factor (U2AF) is an essential splicing factor composed of two subunits, a large, 65-kDa subunit (U2AF(65)) and a small subunit, U2AF(35). U2AF(65) binds to the polypyrimidine tract upstream from the 3' splice site and promotes U2 snRNP binding to the pre-mRNA. Based on in vitro studies, it has been proposed that U2AF(35) plays a role in assisting U2AF(65) recruitment to nonconsensus polypyrimidine tracts. Here we have analyzed in vivo the roles of the two subunits of U2AF in the selection between alternative 3' splice sites associated with polypyrimidine tracts of different strengths. Our results reveal a feedback mechanism by which RNA interference (RNAi)-mediated depletion of U2AF(65) triggers the downregulation of U2AF(35). We further show that the knockdown of each U2AF subunit inhibits weak 3' splice site recognition, while overexpression of U2AF(65) alone is sufficient to activate the selection of this splice site. A variant of U2AF(65) lacking the interaction domain with U2AF(35) shows a reduced ability to promote this splicing event, suggesting that recognition of the weak 3' splice site involves the U2AF heterodimer. Furthermore, our data suggest that, rather than being required for splicing of all pre-mRNA substrates containing a weak polypyrimidine tract, U2AF(35) regulates the selection of weak 3' splice sites in a specific subset of cellular transcripts.
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Affiliation(s)
- Teresa R Pacheco
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisboa, Portugal
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Pacheco TR, Moita LF, Gomes AQ, Hacohen N, Carmo-Fonseca M. RNA interference knockdown of hU2AF35 impairs cell cycle progression and modulates alternative splicing of Cdc25 transcripts. Mol Biol Cell 2006; 17:4187-99. [PMID: 16855028 PMCID: PMC1635340 DOI: 10.1091/mbc.e06-01-0036] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
U2AF is a heterodimeric splicing factor composed of a large (U2AF65) and a small (U2AF35) subunit. In humans, alternative splicing generates two U2AF35 variants, U2AF35a and U2AF35b. Here, we used RNA interference to specifically ablate the expression of each isoform in HeLa cells. Our results show that knockdown of the major U2AF35a isoform reduced cell viability and impaired mitotic progression, leading to accumulation of cells in prometaphase. Microarray analysis revealed that knockdown of U2AF35a affected the expression level of approximately 500 mRNAs, from which >90% were underrepresented relative to the control. Among mRNAs underrepresented in U2AF35a-depleted cells we identified an essential cell cycle gene, Cdc27, for which there was an increase in the ratio between unspliced and spliced RNA and a significant reduction in protein level. Furthermore, we show that depletion of either U2AF35a or U2AF35b altered the ratios of alternatively spliced isoforms of Cdc25B and Cdc25C transcripts. Taken together our results demonstrate that U2AF35a is essential for HeLa cell division and suggest a novel role for both U2AF35 protein isoforms as regulators of alternative splicing of a specific subset of genes.
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Affiliation(s)
- Teresa Raquel Pacheco
- *Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisboa, Portugal
| | - Luís Ferreira Moita
- *Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisboa, Portugal
- Center for Immunology and Inflammatory Diseases, Division of Rheumatology, Allergy, and Immunology, Massachusetts General Hospital, Charlestown, MA 02129; and
| | - Anita Quintal Gomes
- *Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisboa, Portugal
- Departamento de Ciências da Saúde, Universidade da Madeira, 9000-390 Funchal, Portugal
| | - Nir Hacohen
- Center for Immunology and Inflammatory Diseases, Division of Rheumatology, Allergy, and Immunology, Massachusetts General Hospital, Charlestown, MA 02129; and
| | - Maria Carmo-Fonseca
- *Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisboa, Portugal
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Wang BB, Brendel V. Molecular characterization and phylogeny of U2AF35 homologs in plants. PLANT PHYSIOLOGY 2006; 140:624-36. [PMID: 16407443 PMCID: PMC1361329 DOI: 10.1104/pp.105.073858] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
U2AF (U2 small nuclear ribonucleoprotein auxiliary factor) is an essential splicing factor with critical roles in recognition of the 3'-splice site. In animals, the U2AF small subunit (U2AF35) can bind to the 3'-AG intron border and promote U2 small nuclear RNP binding to the branch-point sequences of introns through interaction with the U2AF large subunit. Two copies of U2AF35-encoding genes were identified in Arabidopsis (Arabidopsis thaliana; atU2AF35a and atU2AF35b). Both are expressed in all tissues inspected, with atU2AF35a expressed at a higher level than atU2AF35b in most tissues. Differences in the expression patterns of atU2AF35a and atU2AF35b in roots were revealed by a promoter::beta-glucuronidase assay, with atU2AF35b expressed strongly in whole young roots and root tips and atU2AF35a limited to root vascular regions. Altered expression levels of atU2AF35a or atU2AF35b cause pleiotropic phenotypes (including flowering time, leaf morphology, and flower and silique shape). Novel slicing isoforms were generated from FCA pre-mRNA by splicing of noncanonical introns in plants with altered expression levels of atU2AF35. U2AF35 homologs were also identified from maize (Zea mays) and other plants with large-scale expressed sequence tag projects. A C-terminal motif (named SERE) is highly conserved in all seed plant protein homologs, suggesting it may have an important function specific to higher plants.
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Affiliation(s)
- Bing-Bing Wang
- Department of Genetics, Development and Cell Biology , Iowa State University, Ames, Iowa 50010, USA
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D'Souza I, Schellenberg GD. Arginine/serine-rich protein interaction domain-dependent modulation of a tau exon 10 splicing enhancer: altered interactions and mechanisms for functionally antagonistic FTDP-17 mutations Delta280K AND N279K. J Biol Chem 2005; 281:2460-9. [PMID: 16308321 DOI: 10.1074/jbc.m505809200] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Tau exon 10 splicing is altered by autosomal dominant mutations that cause frontotemporal dementia with parkinsonism chromosome 17-type and by unknown mechanisms in other related neurodegenerative disorders. Identifying cis- and trans-regulators of tau exon 10 splicing is therefore crucial for understanding disease mechanisms. We previously identified several splicing enhancers and silencers within exon 10 and intron 10. Here, we show that splicing factors SF2/ASF, Tra2beta, and a 50-kDa nuclear protein bind in vitro to the polypurine enhancer at the 5' end of exon 10. Disease splicing mutations N279K and Delta280K disrupt the enhancer and alter associations with these factors. N279K targets robustly bind Tra2beta compared with the normal enhancer, which may explain why N279K enhances exon 10 splicing in vivo. In contrast, factor associations with Delta280K targets are nearly undetectable, explaining why Delta280K almost abolishes exon 10 splicing in vivo. Small interfering RNA-mediated suppression of endogenous SF2/ASF and Tra2beta significantly reduces exon 10 splicing. Exogenous SF2/ASF dramatically enhances normal exon 10 splicing and efficiently rescues the Delta280K splicing defect. Domain deletion analyses show that the C-terminal RS domains of SF2/ASF and Tra2beta are required for normal exon 10 splicing in vivo. In contrast to Tra2beta, the SF2/ASF RS domain remains essential in the presence of a strengthened enhancer or when either weak splice site is strengthened. The data suggest that SF2/ASF has both essential and regulatory roles, whereas Tra2beta has a supporting role in exon 10 splicing.
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Affiliation(s)
- Ian D'Souza
- Department of Medicine (Division of Gerontology and Geriatric Medicine), Pharmacology and Neurology, University of Washington, Seattle, Washington 98195, USA.
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Glanzer J, Miyashiro KY, Sul JY, Barrett L, Belt B, Haydon P, Eberwine J. RNA splicing capability of live neuronal dendrites. Proc Natl Acad Sci U S A 2005; 102:16859-64. [PMID: 16275927 PMCID: PMC1277967 DOI: 10.1073/pnas.0503783102] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Dendrites are specialized extensions of the neuronal soma that contain components of the cellular machinery involved in RNA and protein metabolism. Several dendritically localized proteins are associated with the precursor-mRNA (pre-mRNA) splicing complex, or spliceosome. Although some spliceosome-related, RNA-binding proteins are known to subserve separate cytoplasmic functions when moving between the nucleus and cytoplasm, little is known about the pre-mRNA splicing capacity of intact dendrites. Here, we demonstrate the presence and functionality of pre-mRNA-splicing components in dendrites. When isolated dendrites are transfected with a chicken delta-crystallin pre-mRNA or luciferase reporter pre-mRNA, splicing junctions clustered at or near expected splice sites are observed. Additionally, in vitro synaptoneurosome experiments show that this subcellular fraction contains a similar complement of splicing factors that is capable of splicing chicken delta-crystallin pre-mRNA. These observations suggest that pre-mRNA-splicing factors found in the dendroplasm retain the potential to promote pre-mRNA splicing.
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Affiliation(s)
- J Glanzer
- Department of Pharmacology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA
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50
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Park E, Han J, Son GH, Lee MS, Chung S, Park SH, Park K, Lee KH, Choi S, Seong JY, Kim K. Cooperative actions of Tra2alpha with 9G8 and SRp30c in the RNA splicing of the gonadotropin-releasing hormone gene transcript. J Biol Chem 2005; 281:401-9. [PMID: 16249178 DOI: 10.1074/jbc.m505814200] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In earlier studies, we demonstrated that excision of the first intron (intron A) from the gonadotropin-releasing hormone (GnRH) transcript is highly cell type- and developmental stage-specific. The removal of GnRH intron A requires exonic splicing enhancers on exons 3 and 4 (ESE3 and ESE4, respectively). Tra2alpha,a serine/arginine-rich (SR)-like protein, specifically binds to ESE4, although it requires additional nuclear co-factors for efficient removal of this intron. In the present study, we demonstrate the cooperative action of multiple SR proteins in the regulation of GnRH pre-mRNA splicing. SRp30c specifically binds to both ESE3 and ESE4, whereas 9G8 binds to an element in exon 3 and strongly enhances the excision of GnRH intron A in the presence of minimal amount of other nuclear components. Interestingly, Tra2alpha can interact with either 9G8 or SRp30c, whereas no interaction between 9G8 and SRp30c is observed. Tra2alpha has an additive effect on the RNA binding of these proteins. Overexpression or knock-down of these three proteins in cultured cells further suggests their essential role in intron A excision activities, and their presence in GnRH neurons of the mouse preoptic area further strengthens this possibility. Together, these results indicate that interaction of Tra2alpha with 9G8 and SRp30c appears to be crucial for ESE-dependent GnRH pre-mRNA splicing, allowing efficient generation of mature mRNA in GnRH-producing cells.
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Affiliation(s)
- Eonyoung Park
- School of Biological Sciences, Seoul National University, Seoul 151-742, Korea
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