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Alammari F, Al-Hujaily EM, Alshareeda A, Albarakati N, Al-Sowayan BS. Hidden regulators: the emerging roles of lncRNAs in brain development and disease. Front Neurosci 2024; 18:1392688. [PMID: 38841098 PMCID: PMC11150811 DOI: 10.3389/fnins.2024.1392688] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2024] [Accepted: 04/22/2024] [Indexed: 06/07/2024] Open
Abstract
Long non-coding RNAs (lncRNAs) have emerged as critical players in brain development and disease. These non-coding transcripts, which once considered as "transcriptional junk," are now known for their regulatory roles in gene expression. In brain development, lncRNAs participate in many processes, including neurogenesis, neuronal differentiation, and synaptogenesis. They employ their effect through a wide variety of transcriptional and post-transcriptional regulatory mechanisms through interactions with chromatin modifiers, transcription factors, and other regulatory molecules. Dysregulation of lncRNAs has been associated with certain brain diseases, including Alzheimer's disease, Parkinson's disease, cancer, and neurodevelopmental disorders. Altered expression and function of specific lncRNAs have been implicated with disrupted neuronal connectivity, impaired synaptic plasticity, and aberrant gene expression pattern, highlighting the functional importance of this subclass of brain-enriched RNAs. Moreover, lncRNAs have been identified as potential biomarkers and therapeutic targets for neurological diseases. Here, we give a comprehensive review of the existing knowledge of lncRNAs. Our aim is to provide a better understanding of the diversity of lncRNA structure and functions in brain development and disease. This holds promise for unravelling the complexity of neurodevelopmental and neurodegenerative disorders, paving the way for the development of novel biomarkers and therapeutic targets for improved diagnosis and treatment.
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Affiliation(s)
- Farah Alammari
- Department of Blood and Cancer Research, King Abdullah International Medical Research Center, Riyadh, Saudi Arabia
- Clinical Laboratory Sciences Department, College of Applied Medical Sciences, King Saud Bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia
- King Saud Bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia
| | - Ensaf M. Al-Hujaily
- Department of Blood and Cancer Research, King Abdullah International Medical Research Center, Riyadh, Saudi Arabia
- King Saud Bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia
| | - Alaa Alshareeda
- Department of Blood and Cancer Research, King Abdullah International Medical Research Center, Riyadh, Saudi Arabia
- King Saud Bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia
- Saudi Biobank Department, King Abdullah International Medical Research Center, Riyadh, Saudi Arabia
| | - Nada Albarakati
- Department of Blood and Cancer Research, King Abdullah International Medical Research Center, Jeddah, Saudi Arabia
- King Saud Bin Abdulaziz University for Health Sciences, Ministry of the National Guard-Health Affairs, Jeddah, Saudi Arabia
| | - Batla S. Al-Sowayan
- Department of Blood and Cancer Research, King Abdullah International Medical Research Center, Riyadh, Saudi Arabia
- King Saud Bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia
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2
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Cho S, Chun Y, He L, Ramirez CB, Ganesh KS, Jeong K, Song J, Cheong JG, Li Z, Choi J, Kim J, Koundouros N, Ding F, Dephoure N, Jang C, Blenis J, Lee G. FAM120A couples SREBP-dependent transcription and splicing of lipogenesis enzymes downstream of mTORC1. Mol Cell 2023; 83:3010-3026.e8. [PMID: 37595559 PMCID: PMC10494788 DOI: 10.1016/j.molcel.2023.07.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Revised: 05/23/2023] [Accepted: 07/15/2023] [Indexed: 08/20/2023]
Abstract
The mechanistic target of rapamycin complex 1 (mTORC1) is a master regulator of cell growth that stimulates macromolecule synthesis through transcription, RNA processing, and post-translational modification of metabolic enzymes. However, the mechanisms of how mTORC1 orchestrates multiple steps of gene expression programs remain unclear. Here, we identify family with sequence similarity 120A (FAM120A) as a transcription co-activator that couples transcription and splicing of de novo lipid synthesis enzymes downstream of mTORC1-serine/arginine-rich protein kinase 2 (SRPK2) signaling. The mTORC1-activated SRPK2 phosphorylates splicing factor serine/arginine-rich splicing factor 1 (SRSF1), enhancing its binding to FAM120A. FAM120A directly interacts with a lipogenic transcription factor SREBP1 at active promoters, thereby bridging the newly transcribed lipogenic genes from RNA polymerase II to the SRSF1 and U1-70K-containing RNA-splicing machinery. This mTORC1-regulated, multi-protein complex promotes efficient splicing and stability of lipogenic transcripts, resulting in fatty acid synthesis and cancer cell proliferation. These results elucidate FAM120A as a critical transcription co-factor that connects mTORC1-dependent gene regulation programs for anabolic cell growth.
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Affiliation(s)
- Sungyun Cho
- Department of Pharmacology, Weill Cornell Medicine, Cornell University, New York, NY, USA
| | - Yujin Chun
- Department of Microbiology and Molecular Genetics, School of Medicine, University of California Irvine, Irvine, CA, USA
| | - Long He
- Department of Pharmacology, Weill Cornell Medicine, Cornell University, New York, NY, USA
| | - Cuauhtemoc B Ramirez
- Department of Microbiology and Molecular Genetics, School of Medicine, University of California Irvine, Irvine, CA, USA; Department of Biological Chemistry, School of Medicine, University of California Irvine, Irvine, CA, USA
| | - Kripa S Ganesh
- Department of Biochemistry, Weill Cornell Medicine, Cornell University, New York, NY, USA
| | - Kyungjo Jeong
- Department of Biomedical Sciences, College of Medicine, Korea University, Seoul, South Korea
| | - Junho Song
- Department of Biomedical Sciences, College of Medicine, Korea University, Seoul, South Korea
| | - Jin Gyu Cheong
- Department of Pathology and Laboratory Medicine, Weill Cornell Medicine, Cornell University, New York, NY, USA
| | - Zhongchi Li
- Department of Pharmacology, Weill Cornell Medicine, Cornell University, New York, NY, USA
| | - Jungmin Choi
- Department of Biomedical Sciences, College of Medicine, Korea University, Seoul, South Korea; Department of Genetics, Yale School of Medicine, Yale University, New Haven, CT, USA
| | - Joohwan Kim
- Department of Microbiology and Molecular Genetics, School of Medicine, University of California Irvine, Irvine, CA, USA
| | - Nikos Koundouros
- Department of Pharmacology, Weill Cornell Medicine, Cornell University, New York, NY, USA; Meyer Cancer Center, Weill Cornell Medicine, Cornell University, New York, NY, USA
| | - Fangyuan Ding
- Department of Biomedical Engineering, Department of Developmental and Cell Biology, Department of Pharmaceutical Sciences, Center for Synthetic Biology, and Center for Neural Circuit Mapping, University of California Irvine, Irvine, CA, USA; Center for Complex Biological Systems and Chao Family Comprehensive Cancer Center, University of California Irvine, Irvine, CA, USA
| | - Noah Dephoure
- Meyer Cancer Center, Weill Cornell Medicine, Cornell University, New York, NY, USA
| | - Cholsoon Jang
- Department of Biological Chemistry, School of Medicine, University of California Irvine, Irvine, CA, USA; Center for Complex Biological Systems and Chao Family Comprehensive Cancer Center, University of California Irvine, Irvine, CA, USA; Center for Epigenetics and Metabolism, University of California Irvine, Irvine, CA, USA
| | - John Blenis
- Department of Pharmacology, Weill Cornell Medicine, Cornell University, New York, NY, USA; Meyer Cancer Center, Weill Cornell Medicine, Cornell University, New York, NY, USA.
| | - Gina Lee
- Department of Microbiology and Molecular Genetics, School of Medicine, University of California Irvine, Irvine, CA, USA; Center for Complex Biological Systems and Chao Family Comprehensive Cancer Center, University of California Irvine, Irvine, CA, USA; Center for Epigenetics and Metabolism, University of California Irvine, Irvine, CA, USA.
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3
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Stanley RF, Abdel-Wahab O. Dysregulation and therapeutic targeting of RNA splicing in cancer. NATURE CANCER 2022; 3:536-546. [PMID: 35624337 PMCID: PMC9551392 DOI: 10.1038/s43018-022-00384-z] [Citation(s) in RCA: 54] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Accepted: 04/22/2022] [Indexed: 05/15/2023]
Abstract
High-throughput sequencing and functional characterization of the cancer transcriptome have uncovered cancer-specific dysregulation of RNA splicing across a variety of cancers. Alterations in the cancer genome and dysregulation of RNA splicing factors lead to missplicing, splicing alteration-dependent gene expression and, in some cases, generation of novel splicing-derived proteins. Here, we review recent advances in our understanding of aberrant splicing in cancer pathogenesis and present strategies to harness cancer-specific aberrant splicing for therapeutic intent.
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Affiliation(s)
- Robert F Stanley
- Human Oncology and Pathogenesis Program and Leukemia Service, Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Omar Abdel-Wahab
- Human Oncology and Pathogenesis Program and Leukemia Service, Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY, USA.
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4
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Jobbins AM, Campagne S, Weinmeister R, Lucas CM, Gosliga AR, Clery A, Chen L, Eperon LP, Hodson MJ, Hudson AJ, Allain FHT, Eperon IC. Exon-independent recruitment of SRSF1 is mediated by U1 snRNP stem-loop 3. EMBO J 2022; 41:e107640. [PMID: 34779515 PMCID: PMC8724738 DOI: 10.15252/embj.2021107640] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Revised: 10/04/2021] [Accepted: 10/07/2021] [Indexed: 12/11/2022] Open
Abstract
SRSF1 protein and U1 snRNPs are closely connected splicing factors. They both stimulate exon inclusion, SRSF1 by binding to exonic splicing enhancer sequences (ESEs) and U1 snRNPs by binding to the downstream 5' splice site (SS), and both factors affect 5' SS selection. The binding of U1 snRNPs initiates spliceosome assembly, but SR proteins such as SRSF1 can in some cases substitute for it. The mechanistic basis of this relationship is poorly understood. We show here by single-molecule methods that a single molecule of SRSF1 can be recruited by a U1 snRNP. This reaction is independent of exon sequences and separate from the U1-independent process of binding to an ESE. Structural analysis and cross-linking data show that SRSF1 contacts U1 snRNA stem-loop 3, which is required for splicing. We suggest that the recruitment of SRSF1 to a U1 snRNP at a 5'SS is the basis for exon definition by U1 snRNP and might be one of the principal functions of U1 snRNPs in the core reactions of splicing in mammals.
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Affiliation(s)
- Andrew M Jobbins
- Leicester Institute of Structural & Chemical Biology and Department of Molecular & Cell BiologyUniversity of LeicesterLeicesterUK
- Present address:
MRC London Institute of Medical SciencesLondonUK
- Present address:
Institute of Clinical SciencesImperial College LondonLondonUK
| | - Sébastien Campagne
- Institute of BiochemistryETH ZürichSwitzerland
- Present address:
Inserm U1212CNRS UMR5320ARNA LaboratoryBordeaux CedexFrance
| | - Robert Weinmeister
- Leicester Institute of Structural & Chemical Biology and Department of Molecular & Cell BiologyUniversity of LeicesterLeicesterUK
- Leicester Institute of Structural & Chemical Biology and Department of ChemistryUniversity of LeicesterLeicesterUK
| | - Christian M Lucas
- Leicester Institute of Structural & Chemical Biology and Department of Molecular & Cell BiologyUniversity of LeicesterLeicesterUK
| | - Alison R Gosliga
- Leicester Institute of Structural & Chemical Biology and Department of Molecular & Cell BiologyUniversity of LeicesterLeicesterUK
- Present address:
Institut für Industrielle GenetikAbt.(eilung) SystembiologieUniversität StuttgartStuttgartGermany
| | | | - Li Chen
- Leicester Institute of Structural & Chemical Biology and Department of Molecular & Cell BiologyUniversity of LeicesterLeicesterUK
| | - Lucy P Eperon
- Leicester Institute of Structural & Chemical Biology and Department of Molecular & Cell BiologyUniversity of LeicesterLeicesterUK
| | - Mark J Hodson
- Leicester Institute of Structural & Chemical Biology and Department of Molecular & Cell BiologyUniversity of LeicesterLeicesterUK
| | - Andrew J Hudson
- Leicester Institute of Structural & Chemical Biology and Department of ChemistryUniversity of LeicesterLeicesterUK
| | | | - Ian C Eperon
- Leicester Institute of Structural & Chemical Biology and Department of Molecular & Cell BiologyUniversity of LeicesterLeicesterUK
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5
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Yamauchi H, Nishimura K, Yoshimi A. Aberrant RNA splicing and therapeutic opportunities in cancers. Cancer Sci 2021; 113:373-381. [PMID: 34812550 PMCID: PMC8819303 DOI: 10.1111/cas.15213] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Revised: 10/12/2021] [Accepted: 10/18/2021] [Indexed: 12/24/2022] Open
Abstract
There has been accumulating evidence that RNA splicing is frequently dysregulated in a variety of cancers and that hotspot mutations affecting key splicing factors, SF3B1, SRSF2 and U2AF1, are commonly enriched across cancers, strongly suggesting that aberrant RNA splicing is a new class of hallmark that contributes to the initiation and/or maintenance of cancers. In parallel, some studies have demonstrated that cancer cells with global splicing alterations are dependent on the transcriptional products derived from wild‐type spliceosome for their survival, which potentially creates a therapeutic vulnerability in cancers with a mutant spliceosome. It has been c. 10 y since the frequent mutations affecting splicing factors were reported in cancers. Based on these surprising findings, there has been a growing interest in targeting altered splicing in the treatment of cancers, which has promoted a wide variety of investigations including genetic, molecular and biological studies addressing how altered splicing promotes oncogenesis and how cancers bearing alterations in splicing can be targeted therapeutically. In this mini‐review we present a concise trajectory of what has been elucidated regarding the pathogenesis of cancers with aberrant splicing, as well as the development of therapeutic strategies to target global splicing alterations in cancers.
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Affiliation(s)
- Hirofumi Yamauchi
- Cancer RNA Research Unit, National Cancer Center Research Institute, Tokyo, Japan
| | - Kazuki Nishimura
- Cancer RNA Research Unit, National Cancer Center Research Institute, Tokyo, Japan
| | - Akihide Yoshimi
- Cancer RNA Research Unit, National Cancer Center Research Institute, Tokyo, Japan
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6
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Therapeutic approaches targeting splicing factor mutations in myelodysplastic syndromes and acute myeloid leukemia. Curr Opin Hematol 2021; 28:73-79. [PMID: 33492002 DOI: 10.1097/moh.0000000000000632] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE OF REVIEW Mutations in components of the spliceosome are the most common acquired lesions in myelodysplastic syndromes (MDS) and are frequently identified in other myeloid malignancies with a high rate of progression to acute myeloid leukemia (AML) including chronic myelomonocytic leukemia and primary myelofibrosis. The only curative option for these disorders remains allogeneic stem-cell transplantation, which is associated with high morbidity and mortality in these patients. The purpose of this review is to highlight the recent therapeutic developments and strategies being pursued for clinical benefit in splicing factor mutant myeloid malignancies. RECENT FINDINGS Cells harboring splicing factor mutations have increased aberrant splicing leading to R-loop formation and cell cycle stalling that create dependencies on Checkpoint kinase 1 (CHK1) activation and canonical splicing maintained by protein arginine methyltransferase activity. Both targeting of the spliceosome and targeting of the downstream consequences of splicing factor mutation expression show promise as selective strategies for the treatment of splicing factor-mutant myeloid malignancies. SUMMARY An improved understanding of the therapeutic vulnerabilities in splicing factor-mutant MDS and AML has led to the development of clinical trials of small molecule inhibitors that target the spliceosome, ataxia telangectasia and Rad3 related (ATR)-CHK1 pathway, and methylation of splicing components.
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7
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Mikolaskova B, Jurcik M, Cipakova I, Selicky T, Jurcik J, Polakova SB, Stupenova E, Dudas A, Sivakova B, Bellova J, Barath P, Aronica L, Gregan J, Cipak L. Identification of Nrl1 Domains Responsible for Interactions with RNA-Processing Factors and Regulation of Nrl1 Function by Phosphorylation. Int J Mol Sci 2021; 22:7011. [PMID: 34209806 PMCID: PMC8268110 DOI: 10.3390/ijms22137011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Revised: 06/15/2021] [Accepted: 06/27/2021] [Indexed: 12/26/2022] Open
Abstract
Pre-mRNA splicing is a key process in the regulation of gene expression. In the fission yeast Schizosaccharomyces pombe, Nrl1 regulates splicing and expression of several genes and non-coding RNAs, and also suppresses the accumulation of R-loops. Here, we report analysis of interactions between Nrl1 and selected RNA-processing proteins and regulation of Nrl1 function by phosphorylation. Bacterial two-hybrid system (BACTH) assays revealed that the N-terminal region of Nrl1 is important for the interaction with ATP-dependent RNA helicase Mtl1 while the C-terminal region of Nrl1 is important for interactions with spliceosome components Ctr1, Ntr2, and Syf3. Consistent with this result, tandem affinity purification showed that Mtl1, but not Ctr1, Ntr2, or Syf3, co-purifies with the N-terminal region of Nrl1. Interestingly, mass-spectrometry analysis revealed that in addition to previously identified phosphorylation sites, Nrl1 is also phosphorylated on serines 86 and 112, and that Nrl1-TAP co-purifies with Cka1, the catalytic subunit of casein kinase 2. In vitro assay showed that Cka1 can phosphorylate bacterially expressed Nrl1 fragments. An analysis of non-phosphorylatable nrl1 mutants revealed defects in gene expression and splicing consistent with the notion that phosphorylation is an important regulator of Nrl1 function. Taken together, our results provide insights into two mechanisms that are involved in the regulation of the spliceosome-associated factor Nrl1, namely domain-specific interactions between Nrl1 and RNA-processing proteins and post-translational modification of Nrl1 by phosphorylation.
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Affiliation(s)
- Barbora Mikolaskova
- Cancer Research Institute, Biomedical Research Center, Slovak Academy of Sciences, Dubravska Cesta 9, 845 05 Bratislava, Slovakia; (B.M.); (M.J.); (I.C.); (T.S.); (J.J.)
| | - Matus Jurcik
- Cancer Research Institute, Biomedical Research Center, Slovak Academy of Sciences, Dubravska Cesta 9, 845 05 Bratislava, Slovakia; (B.M.); (M.J.); (I.C.); (T.S.); (J.J.)
| | - Ingrid Cipakova
- Cancer Research Institute, Biomedical Research Center, Slovak Academy of Sciences, Dubravska Cesta 9, 845 05 Bratislava, Slovakia; (B.M.); (M.J.); (I.C.); (T.S.); (J.J.)
| | - Tomas Selicky
- Cancer Research Institute, Biomedical Research Center, Slovak Academy of Sciences, Dubravska Cesta 9, 845 05 Bratislava, Slovakia; (B.M.); (M.J.); (I.C.); (T.S.); (J.J.)
| | - Jan Jurcik
- Cancer Research Institute, Biomedical Research Center, Slovak Academy of Sciences, Dubravska Cesta 9, 845 05 Bratislava, Slovakia; (B.M.); (M.J.); (I.C.); (T.S.); (J.J.)
| | - Silvia Bagelova Polakova
- Institute of Animal Biochemistry and Genetics, Centre of Biosciences, Slovak Academy of Sciences, 840 05 Bratislava, Slovakia; (S.B.P.); (E.S.)
| | - Erika Stupenova
- Institute of Animal Biochemistry and Genetics, Centre of Biosciences, Slovak Academy of Sciences, 840 05 Bratislava, Slovakia; (S.B.P.); (E.S.)
| | - Andrej Dudas
- Department of Molecular Biology, Faculty of Natural Sciences, Comenius University, Ilkovicova 6, 842 15 Bratislava, Slovakia;
| | - Barbara Sivakova
- Institute of Chemistry, Slovak Academy of Sciences, Dubravska Cesta 9, 845 38 Bratislava, Slovakia; (B.S.); (J.B.); (P.B.)
| | - Jana Bellova
- Institute of Chemistry, Slovak Academy of Sciences, Dubravska Cesta 9, 845 38 Bratislava, Slovakia; (B.S.); (J.B.); (P.B.)
| | - Peter Barath
- Institute of Chemistry, Slovak Academy of Sciences, Dubravska Cesta 9, 845 38 Bratislava, Slovakia; (B.S.); (J.B.); (P.B.)
- Medirex Group Academy, n.o., Jana Bottu 2, 917 01 Trnava, Slovakia
| | - Lucia Aronica
- Stanford Prevention Research Center, Department of Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA;
| | - Juraj Gregan
- Advanced Microscopy Facility, VBCF, Vienna Biocenter (VBC), 1030 Vienna, Austria;
| | - Lubos Cipak
- Cancer Research Institute, Biomedical Research Center, Slovak Academy of Sciences, Dubravska Cesta 9, 845 05 Bratislava, Slovakia; (B.M.); (M.J.); (I.C.); (T.S.); (J.J.)
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8
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Wagner RE, Frye M. Noncanonical functions of the serine-arginine-rich splicing factor (SR) family of proteins in development and disease. Bioessays 2021; 43:e2000242. [PMID: 33554347 DOI: 10.1002/bies.202000242] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Revised: 01/11/2021] [Accepted: 01/12/2021] [Indexed: 12/19/2022]
Abstract
Members of the serine/arginine (SR)-rich protein family of splicing factors play versatile roles in RNA processing steps and are often essential for normal development. Dynamic changes in RNA processing and turnover allow fast cellular adaptions to a changing microenvironment and thereby closely cooperate with transcription factor networks that establish cell identity within tissues. SR proteins play fundamental roles in the processing of pre-mRNAs by regulating constitutive and alternative splicing. More recently, SR proteins have also been implicated in other aspects of RNA metabolism such as mRNA stability, transport and translation. The- emerging noncanonical functions highlight the multifaceted functions of these SR proteins and identify them as important coordinators of gene expression programmes. Accordingly, most SR proteins are essential for normal cell function and their misregulation contributes to human diseases such as cancer.
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Affiliation(s)
- Rebecca E Wagner
- German Cancer Research Center - Deutsches Krebsforschungszentrum (DKFZ), Heidelberg, Germany
| | - Michaela Frye
- German Cancer Research Center - Deutsches Krebsforschungszentrum (DKFZ), Heidelberg, Germany
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9
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Petasny M, Bentata M, Pawellek A, Baker M, Kay G, Salton M. Splicing to Keep Cycling: The Importance of Pre-mRNA Splicing during the Cell Cycle. Trends Genet 2020; 37:266-278. [PMID: 32950269 DOI: 10.1016/j.tig.2020.08.013] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Revised: 08/09/2020] [Accepted: 08/18/2020] [Indexed: 12/16/2022]
Abstract
Pre-mRNA splicing is a fundamental process in mammalian gene expression, and alternative splicing plays an extensive role in generating protein diversity. Because the majority of genes undergo pre-mRNA splicing, most cellular processes depend on proper spliceosome function. We focus on the cell cycle and describe its dependence on pre-mRNA splicing and accurate alternative splicing. We outline the key cell-cycle factors and their known alternative splicing isoforms. We discuss different levels of pre-mRNA splicing regulation such as post-translational modifications and changes in the expression of splicing factors. We describe the effect of chromatin dynamics on pre-mRNA splicing during the cell cycle. In addition, we focus on spliceosome component SF3B1, which is mutated in many types of cancer, and describe the link between SF3B1 and its inhibitors and the cell cycle.
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Affiliation(s)
- Mayra Petasny
- Department of Biochemistry and Molecular Biology, Institute for Medical Research Israel-Canada, Faculty of Medicine, Hebrew University of Jerusalem, Jerusalem 91120, Israel
| | - Mercedes Bentata
- Department of Biochemistry and Molecular Biology, Institute for Medical Research Israel-Canada, Faculty of Medicine, Hebrew University of Jerusalem, Jerusalem 91120, Israel
| | - Andrea Pawellek
- Centre for Gene Regulation and Expression, School of Life Sciences, University of Dundee, Dundee, UK
| | - Mai Baker
- Department of Biochemistry and Molecular Biology, Institute for Medical Research Israel-Canada, Faculty of Medicine, Hebrew University of Jerusalem, Jerusalem 91120, Israel
| | - Gillian Kay
- Department of Biochemistry and Molecular Biology, Institute for Medical Research Israel-Canada, Faculty of Medicine, Hebrew University of Jerusalem, Jerusalem 91120, Israel
| | - Maayan Salton
- Department of Biochemistry and Molecular Biology, Institute for Medical Research Israel-Canada, Faculty of Medicine, Hebrew University of Jerusalem, Jerusalem 91120, Israel.
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10
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Zheng X, Peng Q, Wang L, Zhang X, Huang L, Wang J, Qin Z. Serine/arginine-rich splicing factors: the bridge linking alternative splicing and cancer. Int J Biol Sci 2020; 16:2442-2453. [PMID: 32760211 PMCID: PMC7378643 DOI: 10.7150/ijbs.46751] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Accepted: 06/22/2020] [Indexed: 01/08/2023] Open
Abstract
The serine/arginine-rich splicing factors (SRs) belong to the serine arginine-rich protein family, which plays an extremely important role in the splicing process of precursor RNA. The SRs recognize the splicing elements on precursor RNA, then recruit and assemble spliceosome to promote or inhibit the occurrence of splicing events. In tumors, aberrant expression of SRs causes abnormal splicing of RNA, contributing to proliferation, migration and apoptosis resistance of tumor cells. Here, we reviewed the vital role of SRs in various tumors and discussed the promise of analyzing mRNA alternative splicing events in tumor. Further, we highlight the challenges and discussed the perspectives for the identification of new potential targets for cancer therapy via SRs family members.
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Affiliation(s)
- Xiang Zheng
- Department of Pathology, Affiliated Hospital of Guilin Medical University, Guilin, Guangxi, 541001, China
| | - Qiu Peng
- Cancer Research Institute, School of Basic Medical Science, Central South University, Changsha, Hunan, 410008, China
| | - Lujuan Wang
- Cancer Research Institute, School of Basic Medical Science, Central South University, Changsha, Hunan, 410008, China
| | - Xuemei Zhang
- Department of Pathology, Affiliated Hospital of Guilin Medical University, Guilin, Guangxi, 541001, China
| | - Lili Huang
- Laboratory of Genetics and Metabolism, Maternal and Child Health Hospital of Guangxi Zhuang Autonomous Region; Guangxi Birth Defects Research and Prevention Institute, Nanning, Guangxi, 530003, China
| | - Jia Wang
- Department of Immunology, Changzhi Medical College, Changzhi, Shanxi, 046000 China
| | - Zailong Qin
- Laboratory of Genetics and Metabolism, Maternal and Child Health Hospital of Guangxi Zhuang Autonomous Region; Guangxi Birth Defects Research and Prevention Institute, Nanning, Guangxi, 530003, China
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11
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Masaki S, Kabuto T, Suzuki K, Kataoka N. Multiple nuclear localization sequences in SRSF4 protein. Genes Cells 2020; 25:327-333. [PMID: 32050040 DOI: 10.1111/gtc.12756] [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: 12/23/2019] [Revised: 02/07/2020] [Accepted: 02/10/2020] [Indexed: 11/29/2022]
Abstract
SRSF4 is one of the members of serine-/arginine (SR)-rich protein family involved in both constitutive and alternative splicing. SRSF4 is localized in the nucleus with speckled pattern, but its nuclear localization signal was not determined. Here, we have identified nuclear localization signals (NLSs) of SRSF4 by using a pyruvate kinase fusion system. As expected, arginine-/serine (RS)-rich domain of SRSF4 confers nuclear localization activity when it is fused to PK protein. We then further delineated the minimum sequences for nuclear localization in RS domain of SRSF4. Surprisingly, RS-rich region does not always have a nuclear localization activity. In addition, basic amino acid stretches that resemble to classical-type NLSs were identified. These results strongly suggest that SRSF4 protein uses two different nuclear import pathways with multiple NLSs in RS domain.
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Affiliation(s)
- So Masaki
- Laboratory for Malignancy Control Research, Medical Innovation Center, Kyoto University Graduate School of Medicine, Kyoto, Japan.,Laboratory of Molecular Medicinal Science, Department of Pharmaceutical Sciences, Ritsumeikan University, Shiga, Japan
| | - Takafumi Kabuto
- Laboratory of Anatomy and Developmental Biology, Kyoto University School of Medicine, Kyoto, Japan
| | - Kenji Suzuki
- Laboratory of Molecular Medicinal Science, Department of Pharmaceutical Sciences, Ritsumeikan University, Shiga, Japan
| | - Naoyuki Kataoka
- Laboratory for Malignancy Control Research, Medical Innovation Center, Kyoto University Graduate School of Medicine, Kyoto, Japan.,Laboratory of Anatomy and Developmental Biology, Kyoto University School of Medicine, Kyoto, Japan.,Laboratory of Cellular Biochemistry, Department of Animal Resource Sciences, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Tokyo, Japan
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12
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Emerging Roles of Long Non-Coding RNAs as Drivers of Brain Evolution. Cells 2019; 8:cells8111399. [PMID: 31698782 PMCID: PMC6912723 DOI: 10.3390/cells8111399] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Revised: 11/01/2019] [Accepted: 11/03/2019] [Indexed: 01/09/2023] Open
Abstract
Mammalian genomes encode tens of thousands of long-noncoding RNAs (lncRNAs), which are capable of interactions with DNA, RNA and protein molecules, thereby enabling a variety of transcriptional and post-transcriptional regulatory activities. Strikingly, about 40% of lncRNAs are expressed specifically in the brain with precisely regulated temporal and spatial expression patterns. In stark contrast to the highly conserved repertoire of protein-coding genes, thousands of lncRNAs have newly appeared during primate nervous system evolution with hundreds of human-specific lncRNAs. Their evolvable nature and the myriad of potential functions make lncRNAs ideal candidates for drivers of human brain evolution. The human brain displays the largest relative volume of any animal species and the most remarkable cognitive abilities. In addition to brain size, structural reorganization and adaptive changes represent crucial hallmarks of human brain evolution. lncRNAs are increasingly reported to be involved in neurodevelopmental processes suggested to underlie human brain evolution, including proliferation, neurite outgrowth and synaptogenesis, as well as in neuroplasticity. Hence, evolutionary human brain adaptations are proposed to be essentially driven by lncRNAs, which will be discussed in this review.
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13
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Obeng EA, Stewart C, Abdel-Wahab O. Altered RNA Processing in Cancer Pathogenesis and Therapy. Cancer Discov 2019; 9:1493-1510. [PMID: 31611195 PMCID: PMC6825565 DOI: 10.1158/2159-8290.cd-19-0399] [Citation(s) in RCA: 83] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Revised: 06/21/2019] [Accepted: 08/08/2019] [Indexed: 12/17/2022]
Abstract
Major advances in our understanding of cancer pathogenesis and therapy have come from efforts to catalog genomic alterations in cancer. A growing number of large-scale genomic studies have uncovered mutations that drive cancer by perturbing cotranscriptional and post-transcriptional regulation of gene expression. These include alterations that affect each phase of RNA processing, including splicing, transport, editing, and decay of messenger RNA. The discovery of these events illuminates a number of novel therapeutic vulnerabilities generated by aberrant RNA processing in cancer, several of which have progressed to clinical development. SIGNIFICANCE: There is increased recognition that genetic alterations affecting RNA splicing and polyadenylation are common in cancer and may generate novel therapeutic opportunities. Such mutations may occur within an individual gene or in RNA processing factors themselves, thereby influencing splicing of many downstream target genes. This review discusses the biological impact of these mutations on tumorigenesis and the therapeutic approaches targeting cells bearing these mutations.
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Affiliation(s)
- Esther A Obeng
- Department of Oncology, St. Jude Children's Research Hospital, Memphis, Tennessee.
| | - Connor Stewart
- Human Oncology and Pathogenesis Program and Leukemia Service, Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, New York
| | - Omar Abdel-Wahab
- Human Oncology and Pathogenesis Program and Leukemia Service, Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, New York.
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Park YJ, Lee JH, Kim JY, Park CM. Alternative RNA Splicing Expands the Developmental Plasticity of Flowering Transition. FRONTIERS IN PLANT SCIENCE 2019; 10:606. [PMID: 31134122 PMCID: PMC6517538 DOI: 10.3389/fpls.2019.00606] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Accepted: 04/25/2019] [Indexed: 05/03/2023]
Abstract
Precise control of the developmental phase transitions, which ranges from seed germination to flowering induction and senescence, is essential for propagation and reproductive success in plants. Flowering induction represents the vegetative-to-reproductive phase transition. An extensive array of genes controlling the flowering transition has been identified, and signaling pathways that incorporate endogenous and environmental cues into the developmental phase transition have been explored in various plant species. Notably, recent accumulating evidence indicate that multiple transcripts are often produced from many of the flowering time genes via alternative RNA splicing, which is known to diversify the transcriptomes and proteasomes in eukaryotes. It is particularly interesting that some alternatively spliced protein isoforms, including COβ and FT2β, function differentially from or even act as competitive inhibitors of the corresponding functional proteins by forming non-functional heterodimers. The alternative splicing events of the flowering time genes are modulated by developmental and environmental signals. It is thus necessary to elucidate molecular schemes controlling alternative splicing and functional characterization of splice protein variants for understanding how genetic diversity and developmental plasticity of the flowering transition are achieved in optimizing the time of flowering under changing climates. In this review, we present current knowledge on the alternative splicing-driven control of flowering time. In addition, we discuss physiological and biochemical importance of the alternative splicing events that occur during the flowering transition as a molecular means of enhancing plant adaptation capabilities.
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Affiliation(s)
- Young-Joon Park
- Department of Chemistry, Seoul National University, Seoul, South Korea
| | - June-Hee Lee
- Department of Chemistry, Seoul National University, Seoul, South Korea
| | - Jae Young Kim
- Department of Chemistry, Seoul National University, Seoul, South Korea
| | - Chung-Mo Park
- Department of Chemistry, Seoul National University, Seoul, South Korea
- Plant Genomics and Breeding Institute, Seoul National University, Seoul, South Korea
- *Correspondence: Chung-Mo Park,
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15
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Zahler AM, Rogel LE, Glover ML, Yitiz S, Ragle JM, Katzman S. SNRP-27, the C. elegans homolog of the tri-snRNP 27K protein, has a role in 5' splice site positioning in the spliceosome. RNA (NEW YORK, N.Y.) 2018; 24:1314-1325. [PMID: 30006499 PMCID: PMC6140464 DOI: 10.1261/rna.066878.118] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Accepted: 07/12/2018] [Indexed: 05/04/2023]
Abstract
The tri-snRNP 27K protein is a component of the human U4/U6-U5 tri-snRNP and contains an N-terminal phosphorylated RS domain. In a forward genetic screen in C. elegans, we previously identified a dominant mutation, M141T, in the highly-conserved C-terminal region of this protein. The mutant allele promotes changes in cryptic 5' splice site choice. To better understand the function of this poorly characterized splicing factor, we performed high-throughput mRNA sequencing analysis on worms containing this dominant mutation. Comparison of alternative splice site usage between the mutant and wild-type strains led to the identification of 26 native genes whose splicing changes in the presence of the snrp-27 mutation. The changes in splicing are specific to alternative 5' splice sites. Analysis of new alleles suggests that snrp-27 is an essential gene for worm viability. We performed a novel directed-mutation experiment in which we used the CRISPR-cas9 system to randomly generate mutations specifically at M141 of SNRP-27. We identified eight amino acid substitutions at this position that are viable, and three that are homozygous lethal. All viable substitutions at M141 led to varying degrees of changes in alternative 5' splicing of native targets. We hypothesize a role for this SR-related factor in maintaining the position of the 5' splice site as U1snRNA trades interactions at the 5' end of the intron with U6snRNA and PRP8 as the catalytic site is assembled.
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Affiliation(s)
- Alan M Zahler
- Department of MCD Biology and Center for Molecular Biology of RNA, University of California Santa Cruz, Santa Cruz, California 95064, USA
| | - Lucero E Rogel
- Department of MCD Biology and Center for Molecular Biology of RNA, University of California Santa Cruz, Santa Cruz, California 95064, USA
| | - Marissa L Glover
- Department of MCD Biology and Center for Molecular Biology of RNA, University of California Santa Cruz, Santa Cruz, California 95064, USA
| | - Samira Yitiz
- Department of MCD Biology and Center for Molecular Biology of RNA, University of California Santa Cruz, Santa Cruz, California 95064, USA
| | - J Matthew Ragle
- Department of MCD Biology and Center for Molecular Biology of RNA, University of California Santa Cruz, Santa Cruz, California 95064, USA
| | - Sol Katzman
- Center for Biomolecular Science and Engineering, University of California Santa Cruz, Santa Cruz, California 95064, USA
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16
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Liu X, Klein PS. Glycogen synthase kinase-3 and alternative splicing. WILEY INTERDISCIPLINARY REVIEWS-RNA 2018; 9:e1501. [PMID: 30118183 DOI: 10.1002/wrna.1501] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Revised: 07/03/2018] [Accepted: 07/09/2018] [Indexed: 12/16/2022]
Abstract
Glycogen synthase kinase-3 (GSK-3) is a highly conserved negative regulator of receptor tyrosine kinase, cytokine, and Wnt signaling pathways. Stimulation of these pathways inhibits GSK-3 to modulate diverse downstream effectors that include transcription factors, nutrient sensors, glycogen synthesis, mitochondrial function, circadian rhythm, and cell fate. GSK-3 also regulates alternative splicing in response to T-cell receptor activation, and recent phosphoproteomic studies have revealed that multiple splicing factors and regulators of RNA biosynthesis are phosphorylated in a GSK-3-dependent manner. Furthermore, inhibition of GSK-3 alters the splicing of hundreds of mRNAs, indicating a broad role for GSK-3 in the regulation of RNA processing. GSK-3-regulated phosphoproteins include SF3B1, SRSF2, PSF, RBM8A, nucleophosmin 1 (NPM1), and PHF6, many of which are mutated in leukemia and myelodysplasia. As GSK-3 is inhibited by pathways that are pathologically activated in leukemia and loss of Gsk3 in hematopoietic cells causes a severe myelodysplastic neoplasm in mice, these findings strongly implicate GSK-3 as a critical regulator of mRNA processing in normal and malignant hematopoiesis. This article is categorized under: RNA Processing > Splicing Mechanisms RNA Processing > Splicing Regulation/Alternative Splicing RNA in Disease and Development > RNA in Disease RNA Interactions with Proteins and Other Molecules > Protein-RNA Interactions: Functional Implications.
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Affiliation(s)
- Xiaolei Liu
- Division of Hematology-Oncology, Department of Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania
| | - Peter S Klein
- Division of Hematology-Oncology, Department of Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania
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17
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Romero-Barrios N, Legascue MF, Benhamed M, Ariel F, Crespi M. Splicing regulation by long noncoding RNAs. Nucleic Acids Res 2018; 46:2169-2184. [PMID: 29425321 PMCID: PMC5861421 DOI: 10.1093/nar/gky095] [Citation(s) in RCA: 182] [Impact Index Per Article: 30.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Revised: 01/05/2018] [Accepted: 02/01/2018] [Indexed: 12/13/2022] Open
Abstract
Massive high-throughput sequencing techniques allowed the identification of thousands of noncoding RNAs (ncRNAs) and a plethora of different mRNA processing events occurring in higher organisms. Long ncRNAs can act directly as long transcripts or can be processed into active small si/miRNAs. They can modulate mRNA cleavage, translational repression or the epigenetic landscape of their target genes. Recently, certain long ncRNAs have been shown to play a crucial role in the regulation of alternative splicing in response to several stimuli or during disease. In this review, we focus on recent discoveries linking gene regulation by alternative splicing and its modulation by long and small ncRNAs.
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Affiliation(s)
- Natali Romero-Barrios
- Institute of Plant Sciences Paris-Saclay (IPS2), CNRS, INRA, Universities Paris-Sud, Evry and Paris-Diderot, Sorbonne Paris-Cite, University of Paris-Saclay, Batiment 630, 91405 Orsay, France
| | - Maria Florencia Legascue
- Instituto de Agrobiotecnología del Litoral, CONICET, Universidad Nacional del Litoral, Colectora Ruta Nacional 168 km 0, 3000 Santa Fe, Argentina
| | - Moussa Benhamed
- Institute of Plant Sciences Paris-Saclay (IPS2), CNRS, INRA, Universities Paris-Sud, Evry and Paris-Diderot, Sorbonne Paris-Cite, University of Paris-Saclay, Batiment 630, 91405 Orsay, France
| | - Federico Ariel
- Instituto de Agrobiotecnología del Litoral, CONICET, Universidad Nacional del Litoral, Colectora Ruta Nacional 168 km 0, 3000 Santa Fe, Argentina
| | - Martin Crespi
- Institute of Plant Sciences Paris-Saclay (IPS2), CNRS, INRA, Universities Paris-Sud, Evry and Paris-Diderot, Sorbonne Paris-Cite, University of Paris-Saclay, Batiment 630, 91405 Orsay, France
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18
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Mobilization of a splicing factor through a nuclear kinase-kinase complex. Biochem J 2018; 475:677-690. [PMID: 29335301 DOI: 10.1042/bcj20170672] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Revised: 01/09/2018] [Accepted: 01/12/2018] [Indexed: 12/17/2022]
Abstract
The splicing of mRNA is dependent on serine-arginine (SR) proteins that are mobilized from membrane-free, nuclear speckles to the nucleoplasm by the Cdc2-like kinases (CLKs). This movement is critical for SR protein-dependent assembly of the macromolecular spliceosome. Although CLK1 facilitates such trafficking through the phosphorylation of serine-proline dipeptides in the prototype SR protein SRSF1, an unrelated enzyme known as SR protein kinase 1 (SRPK1) performs the same function but does not efficiently modify these dipeptides in SRSF1. We now show that the ability of SRPK1 to mobilize SRSF1 from speckles to the nucleoplasm is dependent on active CLK1. Diffusion from speckles is promoted by the formation of an SRPK1-CLK1 complex that facilitates dissociation of SRSF1 from CLK1 and enhances the phosphorylation of several serine-proline dipeptides in this SR protein. Down-regulation of either kinase blocks EGF-stimulated mobilization of nuclear SRSF1. These findings establish a signaling pathway that connects SRPKs to SR protein activation through the associated CLK family of kinases.
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19
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Sánchez-Hernández N, Prieto-Sánchez S, Moreno-Castro C, Muñoz-Cobo JP, El Yousfi Y, Boyero-Corral S, Suñé-Pou M, Hernández-Munain C, Suñé C. Targeting proteins to RNA transcription and processing sites within the nucleus. Int J Biochem Cell Biol 2017; 91:194-202. [DOI: 10.1016/j.biocel.2017.06.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Revised: 05/26/2017] [Accepted: 06/01/2017] [Indexed: 12/26/2022]
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20
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Pawellek A, Ryder U, Tammsalu T, King LJ, Kreinin H, Ly T, Hay RT, Hartley RC, Lamond AI. Characterisation of the biflavonoid hinokiflavone as a pre-mRNA splicing modulator that inhibits SENP. eLife 2017; 6:27402. [PMID: 28884683 PMCID: PMC5619949 DOI: 10.7554/elife.27402] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2017] [Accepted: 09/06/2017] [Indexed: 12/17/2022] Open
Abstract
We have identified the plant biflavonoid hinokiflavone as an inhibitor of splicing in vitro and modulator of alternative splicing in cells. Chemical synthesis confirms hinokiflavone is the active molecule. Hinokiflavone inhibits splicing in vitro by blocking spliceosome assembly, preventing formation of the B complex. Cells treated with hinokiflavone show altered subnuclear organization specifically of splicing factors required for A complex formation, which relocalize together with SUMO1 and SUMO2 into enlarged nuclear speckles containing polyadenylated RNA. Hinokiflavone increases protein SUMOylation levels, both in in vitro splicing reactions and in cells. Hinokiflavone also inhibited a purified, E. coli expressed SUMO protease, SENP1, in vitro, indicating the increase in SUMOylated proteins results primarily from inhibition of de-SUMOylation. Using a quantitative proteomics assay we identified many SUMO2 sites whose levels increased in cells following hinokiflavone treatment, with the major targets including six proteins that are components of the U2 snRNP and required for A complex formation.
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Affiliation(s)
- Andrea Pawellek
- Centre for Gene Regulation and Expression, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Ursula Ryder
- Centre for Gene Regulation and Expression, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Triin Tammsalu
- Centre for Gene Regulation and Expression, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Lewis J King
- WestCHEM, School of Chemistry, University of Glasgow, Glasgow, United Kingdom
| | - Helmi Kreinin
- WestCHEM, School of Chemistry, University of Glasgow, Glasgow, United Kingdom
| | - Tony Ly
- Centre for Gene Regulation and Expression, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Ronald T Hay
- Centre for Gene Regulation and Expression, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Richard C Hartley
- WestCHEM, School of Chemistry, University of Glasgow, Glasgow, United Kingdom
| | - Angus I Lamond
- Centre for Gene Regulation and Expression, School of Life Sciences, University of Dundee, Dundee, United Kingdom
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21
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Preußner M, Goldammer G, Neumann A, Haltenhof T, Rautenstrauch P, Müller-McNicoll M, Heyd F. Body Temperature Cycles Control Rhythmic Alternative Splicing in Mammals. Mol Cell 2017; 67:433-446.e4. [DOI: 10.1016/j.molcel.2017.06.006] [Citation(s) in RCA: 79] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Revised: 04/27/2017] [Accepted: 06/07/2017] [Indexed: 12/12/2022]
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22
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Aubol BE, Wu G, Keshwani MM, Movassat M, Fattet L, Hertel KJ, Fu XD, Adams JA. Release of SR Proteins from CLK1 by SRPK1: A Symbiotic Kinase System for Phosphorylation Control of Pre-mRNA Splicing. Mol Cell 2016; 63:218-228. [PMID: 27397683 DOI: 10.1016/j.molcel.2016.05.034] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2015] [Revised: 04/26/2016] [Accepted: 05/25/2016] [Indexed: 11/26/2022]
Abstract
Phosphorylation has been generally thought to activate the SR family of splicing factors for efficient splice-site recognition, but this idea is incompatible with an early observation that overexpression of an SR protein kinase, such as the CDC2-like kinase 1 (CLK1), weakens splice-site selection. Here, we report that CLK1 binds SR proteins but lacks the mechanism to release phosphorylated SR proteins, thus functionally inactivating the splicing factors. Interestingly, CLK1 overcomes this dilemma through a symbiotic relationship with the serine-arginine protein kinase 1 (SRPK1). We show that SRPK1 interacts with an RS-like domain in the N terminus of CLK1 to facilitate the release of phosphorylated SR proteins, which then promotes efficient splice-site recognition and subsequent spliceosome assembly. These findings reveal an unprecedented signaling mechanism by which two protein kinases fulfill separate catalytic features that are normally encoded in single kinases to institute phosphorylation control of pre-mRNA splicing in the nucleus.
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Affiliation(s)
- Brandon E Aubol
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92093, USA
| | - Guowei Wu
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Malik M Keshwani
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92093, USA
| | - Maliheh Movassat
- Department of Microbiology and Molecular Genetics, University of California, Irvine, Irvine, CA 92697, USA
| | - Laurent Fattet
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92093, USA
| | - Klemens J Hertel
- Department of Microbiology and Molecular Genetics, University of California, Irvine, Irvine, CA 92697, USA
| | - Xiang-Dong Fu
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Joseph A Adams
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92093, USA.
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23
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Meyer F. Viral interactions with components of the splicing machinery. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2016; 142:241-68. [PMID: 27571697 DOI: 10.1016/bs.pmbts.2016.05.008] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Eukaryotic genes are often interrupted by stretches of sequence with no protein coding potential or obvious function. After transcription, these interrupting sequences must be removed to give rise to the mature messenger RNA. This fundamental process is called RNA splicing and is achieved by complicated machinery made of protein and RNA that assembles around the RNA to be edited. Viruses also use RNA splicing to maximize their coding potential and economize on genetic space, and use clever strategies to manipulate the splicing machinery to their advantage. This article gives an overview of the splicing process and provides examples of viral strategies that make use of various components of the splicing system to promote their replicative cycle. Representative virus families have been selected to illustrate the interaction with various regulatory proteins and ribonucleoproteins. The unifying theme is fine regulation through protein-protein and protein-RNA interactions with the spliceosome components and associated factors to promote or prevent spliceosome assembly on given splice sites, in addition to a strong influence from cis-regulatory sequences on viral transcripts. Because there is an intimate coupling of splicing with the processes that direct mRNA biogenesis, a description of how these viruses couple the regulation of splicing with the retention or stability of mRNAs is also included. It seems that a unique balance of suppression and activation of splicing and nuclear export works optimally for each family of viruses.
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Affiliation(s)
- F Meyer
- Department of Biochemistry & Molecular Biology, Entomology & Plant Pathology, Mississippi State University, Starkville, MS, USA.
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24
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Sohail M, Xie J. Diverse regulation of 3' splice site usage. Cell Mol Life Sci 2015; 72:4771-93. [PMID: 26370726 PMCID: PMC11113787 DOI: 10.1007/s00018-015-2037-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2015] [Revised: 08/12/2015] [Accepted: 09/03/2015] [Indexed: 01/13/2023]
Abstract
The regulation of splice site (SS) usage is important for alternative pre-mRNA splicing and thus proper expression of protein isoforms in cells; its disruption causes diseases. In recent years, an increasing number of novel regulatory elements have been found within or nearby the 3'SS in mammalian genes. The diverse elements recruit a repertoire of trans-acting factors or form secondary structures to regulate 3'SS usage, mostly at the early steps of spliceosome assembly. Their mechanisms of action mainly include: (1) competition between the factors for RNA elements, (2) steric hindrance between the factors, (3) direct interaction between the factors, (4) competition between two splice sites, or (5) local RNA secondary structures or longer range loops, according to the mode of protein/RNA interactions. Beyond the 3'SS, chromatin remodeling/transcription, posttranslational modifications of trans-acting factors and upstream signaling provide further layers of regulation. Evolutionarily, some of the 3'SS elements seem to have emerged in mammalian ancestors. Moreover, other possibilities of regulation such as that by non-coding RNA remain to be explored. It is thus likely that there are more diverse elements/factors and mechanisms that influence the choice of an intron end. The diverse regulation likely contributes to a more complex but refined transcriptome and proteome in mammals.
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Affiliation(s)
- Muhammad Sohail
- Department of Physiology and Pathophysiology, College of Medicine, Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, R3E 0J9, Canada
| | - Jiuyong Xie
- Department of Physiology and Pathophysiology, College of Medicine, Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, R3E 0J9, Canada.
- Department of Biochemistry and Medical Genetics, College of Medicine, Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, R3E 0J9, Canada.
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25
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Nuclear protein kinase CLK1 uses a non-traditional docking mechanism to select physiological substrates. Biochem J 2015; 472:329-38. [PMID: 26443864 DOI: 10.1042/bj20150903] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Accepted: 10/06/2015] [Indexed: 01/22/2023]
Abstract
Phosphorylation-dependent cell communication requires enzymes that specifically recognize key proteins in a sea of similar, competing substrates. The protein kinases achieve this goal by utilizing docking grooves in the kinase domain or heterologous protein adaptors to reduce 'off pathway' targeting. We now provide evidence that the nuclear protein kinase CLK1 (cell division cycle2-like kinase 1) important for splicing regulation departs from these classic paradigms by using a novel self-association mechanism. The disordered N-terminus of CLK1 induces oligomerization, a necessary event for targeting its physiological substrates the SR protein (splicing factor containing a C-terminal RS domain) family of splicing factors. Increasing the CLK1 concentration enhances phosphorylation of the splicing regulator SRSF1 (SR protein splicing factor 1) compared with the general substrate myelin basic protein (MBP). In contrast, removal of the N-terminus or dilution of CLK1 induces monomer formation and reverses this specificity. CLK1 self-association also occurs in the nucleus, is induced by the N-terminus and is important for localization of the kinase in sub-nuclear compartments known as speckles. These findings present a new picture of substrate recognition for a protein kinase in which an intrinsically disordered domain is used to capture physiological targets with similar disordered domains in a large oligomeric complex while discriminating against non-physiological targets.
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26
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He J, Yao J, Sheng H, Zhu J. Involvement of the dual-specificity tyrosine phosphorylation-regulated kinase 1A-alternative splicing factor-calcium/calmodulin-dependent protein kinase IIδ signaling pathway in myocardial infarction-induced heart failure of rats. J Card Fail 2015; 21:751-60. [PMID: 26067684 DOI: 10.1016/j.cardfail.2015.05.015] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2014] [Revised: 05/28/2015] [Accepted: 05/29/2015] [Indexed: 10/23/2022]
Abstract
BACKGROUND Alternative splicing factor (ASF)-regulated alternative splicing of calcium/calmodulin-dependent protein kinase IIδ (CaMKIIδ) plays an important role in pathologic cardiac remodeling. ASF can be phosphorylated by dual-specificity tyrosine phosphorylation-regulated kinase 1A (Dyrk1A). This study aimed to investigate the possible involvement of the Dyrk1A-ASF-CaMKIIδ signaling pathway in the progression of myocardial infarction (MI)-induced heart failure (HF). METHODS AND RESULTS MI in rats was induced by means of left anterior descending coronary artery ligation. Seven weeks after MI, the increase in left ventricular internal diameter at end-diastole (LVIDd), and the decrease in both ejection fraction (EF) and fractional shortening (FS) indicated that MI rats had developed HF. Quantitative real time reverse-transcription polymerase chain reaction indicated the dysregulation of CaMKIIδ alternative splicing, ie, up-regulation of CaMKIIδA and CaMKIIδC and down-regulation of CaMKIIδB in the hearts of HF rats. Electrophoresis and immunostaining revealed that HF activated the phosphorylation of ASF and affected its subcellular localization. Western blot analysis demonstrated a significant elevation in the activity and expression of Dyrk1A in HF rats. Inversely, treatment of MI-induced HF rats with Dyrk1A inhibitor, either harmine or EGCG, improved the symptoms of HF, reversed the molecular changes of Dyrk1A and ASF, and regulated alternative splicing of CaMKIIδ in HF rats. CONCLUSIONS Enhanced activation of Dyrk1A-ASF-CaMKIIδ signaling pathway may underlie the mechanisms of HF after MI, and Dyrk1A inhibition may contribute to inactivation of this pathway and thereby retard the progression of MI-induced HF.
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Affiliation(s)
- Jing He
- Institute of Cardiovascular Disease, Nantong University, Nantong, Jiangsu, People's Republic of China; Department of Cardiology, Affiliated Hospital of Nantong University, Nantong, Jiangsu, People's Republic of China
| | - Jian Yao
- Department of Histology and Embryology, Nantong University, Nantong, Jiangsu, People's Republic of China
| | - Hongzhuan Sheng
- Institute of Cardiovascular Disease, Nantong University, Nantong, Jiangsu, People's Republic of China; Department of Cardiology, Affiliated Hospital of Nantong University, Nantong, Jiangsu, People's Republic of China.
| | - Jianhua Zhu
- Institute of Cardiovascular Disease, Nantong University, Nantong, Jiangsu, People's Republic of China; Department of Cardiology, Affiliated Hospital of Nantong University, Nantong, Jiangsu, People's Republic of China.
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Lipp JJ, Marvin MC, Shokat KM, Guthrie C. SR protein kinases promote splicing of nonconsensus introns. Nat Struct Mol Biol 2015; 22:611-7. [PMID: 26167880 DOI: 10.1038/nsmb.3057] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Accepted: 06/04/2015] [Indexed: 01/01/2023]
Abstract
Phosphorylation of the spliceosome is essential for RNA splicing, yet how and to what extent kinase signaling affects splicing have not been defined on a genome-wide basis. Using a chemical genetic approach, we show in Schizosaccharomyces pombe that the SR protein kinase Dsk1 is required for efficient splicing of introns with suboptimal splice sites. Systematic substrate mapping in fission yeast and human cells revealed that SRPKs target evolutionarily conserved spliceosomal proteins, including the branchpoint-binding protein Bpb1 (SF1 in humans), by using an RXXSP consensus motif for substrate recognition. Phosphorylation of SF1 increases SF1 binding to introns with nonconsensus splice sites in vitro, and mutation of such sites to consensus relieves the requirement for Dsk1 and phosphorylated Bpb1 in vivo. Modulation of splicing efficiency through kinase signaling pathways may allow tuning of gene expression in response to environmental and developmental cues.
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Affiliation(s)
- Jesse J Lipp
- Department of Cellular and Molecular Pharmacology, Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, California, USA
| | - Michael C Marvin
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, California, USA
| | - Kevan M Shokat
- Department of Cellular and Molecular Pharmacology, Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, California, USA
| | - Christine Guthrie
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, California, USA
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28
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Jakubauskiene E, Vilys L, Makino Y, Poellinger L, Kanopka A. Increased Serine-Arginine (SR) Protein Phosphorylation Changes Pre-mRNA Splicing in Hypoxia. J Biol Chem 2015; 290:18079-18089. [PMID: 26023237 DOI: 10.1074/jbc.m115.639690] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Indexed: 11/06/2022] Open
Abstract
The removal of introns from mRNA precursors (pre-mRNAs) is an essential step in eukaryotic gene expression. The splicing machinery heavily contributes to biological complexity and especially to the ability of cells to adapt to altered cellular conditions. Inhibitory PAS domain protein (IPAS), a dominant negative regulator of hypoxia-inducible gene expression, is generated from hypoxia inducible transcription factor-3α (HIF-3α) pre-mRNA by an alternative splicing mechanism. Inactivation of the IPAS transcript in mice leads to the neo-vascularization of the cornea, suggesting that IPAS is an important regulator of anti-angiogenesis in this tissue. For the first time we demonstrate that serine-arginine (SR) proteins are involved in oxygen tension-dependent changes in pre-mRNA splicing. SR proteins isolated from hypoxic cells differentially interact with RNA (compared with proteins isolated from cells cultured under normoxic conditions). They possess the differential ability to activate hypoxia-dependent splice sites, and they are more phosphorylated than those isolated from normoxic HeLa cells. We also show that expression of SR protein kinases (CLK1, SRPK1, SRPK2) in hypoxic cells is elevated at mRNA and protein levels. Increased expression of CLK1 kinase is regulated by HIFs. Reduction of CLK1 cellular expression levels reduces hypoxia-dependent full-length carbonic anhydrase IX (CAIX) mRNA and CAIX protein formation and changes hypoxia-dependent cysteine-rich angiogenic inducer 61 (Cyr61) mRNA isoform formation profiles.
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Affiliation(s)
- Egle Jakubauskiene
- Department of Immunology and Cell Biology, Vilnius University, Institute of Biotechnology, 02241 Vilnius, Lithuania
| | - Laurynas Vilys
- Department of Immunology and Cell Biology, Vilnius University, Institute of Biotechnology, 02241 Vilnius, Lithuania
| | - Yuichi Makino
- Division of Metabolism and Biosystemic Science, Department of Medicine, Asahikawa Medical College, 078-8510 Asahikawa, Hokkaido, Japan
| | - Lorenz Poellinger
- Department of Cell and Molecular Biology, Medical Nobel Institute, Karolinska Institute, SE-17177 Stockholm, Sweden; Cancer Science Institute, National University of Singapore, 117599 Singapore
| | - Arvydas Kanopka
- Department of Immunology and Cell Biology, Vilnius University, Institute of Biotechnology, 02241 Vilnius, Lithuania.
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29
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Boutz PL, Bhutkar A, Sharp PA. Detained introns are a novel, widespread class of post-transcriptionally spliced introns. Genes Dev 2015; 29:63-80. [PMID: 25561496 PMCID: PMC4281565 DOI: 10.1101/gad.247361.114] [Citation(s) in RCA: 275] [Impact Index Per Article: 30.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Deep sequencing of embryonic stem cell RNA revealed many specific internal introns that are significantly more abundant than the other introns within polyadenylated transcripts. Boutz et al. identified thousands of these “detained” introns (DIs) in human and mouse cell lines as well as the adult mouse liver. Drug inhibition of Clk, a stress-responsive kinase, triggered rapid splicing changes for a specific subset of DIs, altering transcript pools of >300 genes. Srsf4 regulates the splicing of some DIs, particularly in genes encoding RNA processing and splicing factors. Deep sequencing of embryonic stem cell RNA revealed many specific internal introns that are significantly more abundant than the other introns within polyadenylated transcripts; we classified these as “detained” introns (DIs). We identified thousands of DIs, many of which are evolutionarily conserved, in human and mouse cell lines as well as the adult mouse liver. DIs can have half-lives of over an hour yet remain in the nucleus and are not subject to nonsense-mediated decay (NMD). Drug inhibition of Clk, a stress-responsive kinase, triggered rapid splicing changes for a specific subset of DIs; half showed increased splicing, and half showed increased intron detention, altering transcript pools of >300 genes. Srsf4, which undergoes a dramatic phosphorylation shift in response to Clk kinase inhibition, regulates the splicing of some DIs, particularly in genes encoding RNA processing and splicing factors. The splicing of some DIs—including those in Mdm4, a negative regulator of p53—was also altered following DNA damage. After 4 h of Clk inhibition, the expression of >400 genes changed significantly, and almost one-third of these are p53 transcriptional targets. These data suggest a widespread mechanism by which the rate of splicing of DIs contributes to the level of gene expression.
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Affiliation(s)
- Paul L Boutz
- The David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Arjun Bhutkar
- The David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Phillip A Sharp
- The David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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30
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Qi Y, Li Y, Cui SC, Zhao JJ, Liu XY, Ji CX, Sun FY, Xu P, Chen XH. Splicing factor NSSR1 reduces neuronal injury after mouse transient global cerebral ischemia. Glia 2015; 63:826-45. [PMID: 25627895 DOI: 10.1002/glia.22787] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2014] [Revised: 12/08/2014] [Accepted: 12/18/2014] [Indexed: 11/06/2022]
Abstract
This study focuses on the function of NSSR1, a splicing factor, in neuronal injury in the ischemic mouse brain using the transient global cerebral ischemic mouse model and the cultured cells treated with oxygen-glucose deprivation (OGD). The results showed that the cerebral ischemia triggers the expression of NSSR1 in hippocampal astrocytes, predominantly the dephosphorylated NSSR1 proteins, and the Exon3 inclusive NCAM-L1 variant and the Exon4 inclusive CREB variant. While in the hippocampus of astrocyte-specific NSSR1 conditional knockdown (cKD) mice, where cerebral ischemia no longer triggers NSSR1 expression in astrocytes, the expression of Exon3 inclusive NCAM-L1 variant and Exon4 inclusive CREB variant were no longer triggered as well. In addition, the injury of hippocampal neurons was more severe in astrocyte-specific NSSR1 cKD mice compared with in wild-type mice after brain ischemia. Of note, the culture media harvested from the astrocytes with overexpression of NSSR1 or the Exon3 inclusive NCAM-L1 variant, or Exon4 inclusive CREB variant were all able to reduce the neuronal injury induced by OGD. The results provide the evidence demonstrating that: (1) Splicing factor NSSR1 is a new factor involved in reducing ischemic injury. (2) Ischemia induces NSSR1 expression in astrocytes, not in neurons. (3) NSSR1-mediated pathway in astrocytes is required for reducing ischemic neuronal injury. (4) NCAM-L1 and CREB are probably mediators in NSSR1-mediated pathway. In conclusion, our results suggest for the first time that NSSR1 may provide a novel mechanism for reducing neuronal injury after ischemia, probably through regulation on alternative splicing of NCAM-L1 and CREB in astrocytes.
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Affiliation(s)
- Yao Qi
- State Key Laboratory of Medical Neurobiology and Laboratory of Genomic Physiology, Institutes of Brain Science, Department of Neurobiology, School of Basic Medical Sciences, Shanghai Medical College, Fudan University, Shanghai, 200032, China
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31
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Ceramide modulates pre-mRNA splicing to restore the expression of wild-type tumor suppressor p53 in deletion-mutant cancer cells. Biochim Biophys Acta Mol Cell Biol Lipids 2014; 1841:1571-80. [PMID: 25195822 DOI: 10.1016/j.bbalip.2014.08.017] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Revised: 07/25/2014] [Accepted: 08/27/2014] [Indexed: 11/20/2022]
Abstract
Mutants of tumor suppressor p53 not only lose the activity in genome stabilizing and in tumor suppression, but also exhibit oncogenic function in cancer cells. Most efforts in restoring p53 biological activity focus on either altering mutant-protein conformation or introducing an exogenous p53 gene into cells to eliminate p53-mutant cancer cells. Being different from these, we report that ceramide can restore the expression of wild-type p53 and induce p53-dependent apoptosis in deletion-mutant cancer cells. We show that endogenous long-carbon chain ceramide species (C16- to C24-ceramides) and exogenous C6-ceramide, rather than other sphingolipids, restore wild-type mRNA (intact exon-5), phosphorylated protein (Ser15 in exon-5) of p53, and p53-responsive proteins, including p21 and Bax, in ovarian cancer cells, which predominantly express a deleted exon-5 of p53 mutant before treatments. Consequently, the restored p53 sensitizes these p53-mutant cancer cells to DNA damage-induced growth arrest and apoptosis. Furthermore, we elucidate that ceramide activates protein phosphatase-1, and then the dephosphorylated serine/arginine-rich splicing-factor 1 (SRSF1) is translocated to the nucleus, thus promoting pre-mRNA splicing preferentially to wild-type p53 expression. These findings disclose an unrecognized mechanism that pre-mRNA splicing dysfunction can result in p53 deletion-mutants. Ceramide through SRSF1 restores wild-type p53 expression versus deletion-mutant and leads cancer cells to apoptosis. This suggests that heterozygous deletion-mutants of p53 can be restored in posttranscriptional level by using epigenetic approaches.
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32
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Howard JM, Sanford JR. The RNAissance family: SR proteins as multifaceted regulators of gene expression. WILEY INTERDISCIPLINARY REVIEWS-RNA 2014; 6:93-110. [PMID: 25155147 DOI: 10.1002/wrna.1260] [Citation(s) in RCA: 158] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2014] [Revised: 07/09/2014] [Accepted: 07/14/2014] [Indexed: 12/29/2022]
Abstract
Serine and arginine-rich (SR) proteins play multiple roles in the eukaryotic gene expression pathway. Initially described as constitutive and alternative splicing factors, now it is clear that SR proteins are key determinants of exon identity and function as molecular adaptors, linking the pre-messenger RNA (pre-mRNA) to the splicing machinery. In addition, now SR proteins are implicated in many aspects of mRNA and noncoding RNA (ncRNA) processing well beyond splicing. These unexpected roles, including RNA transcription, export, translation, and decay, may prove to be the rule rather than the exception. To simply define, this family of RNA-binding proteins as splicing factors belies the broader roles of SR proteins in post-transcriptional gene expression.
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Affiliation(s)
- Jonathan M Howard
- Department of Molecular, Cellular and Developmental Biology, University of California Santa Cruz, Santa Cruz, CA, USA
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33
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da Glória VG, Martins de Araújo M, Mafalda Santos A, Leal R, de Almeida SF, Carmo AM, Moreira A. T cell activation regulates CD6 alternative splicing by transcription dynamics and SRSF1. THE JOURNAL OF IMMUNOLOGY 2014; 193:391-9. [PMID: 24890719 DOI: 10.4049/jimmunol.1400038] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The T cell-surface glycoprotein CD6 is a modulator of cellular responses and has been implicated in several autoimmune diseases such as multiple sclerosis, rheumatoid arthritis, and psoriasis. During Ag presentation, CD6 is targeted to the immunological synapse in a ligand binding-dependent manner, in which CD6 domain 3 directly contacts CD166, expressed on the APC. T cell activation results in the induction of CD6Δd3, an alternatively spliced isoform that lacks the ligand-binding domain and thus no longer localizes at the immunological synapse. In this study, we investigated the molecular mechanisms regulating the expression of CD6Δd3 upon human primary T cell activation. Using chromatin immunoprecipitation, we observed an increase in RNA polymerase II occupancy along the CD6 gene and augmented CD6 transcription. We showed that activation leads to transcription-related chromatin modifications, revealed by higher CD6 acetylation levels. Modulation of chromatin conformation using a histone deacetylase inhibitor that increases transcription rate causes an increase of exon 5 skipping. We further showed that the splicing factor SRSF1 binds to a regulatory element in CD6 intron 4, activating exon 5 splicing and promoting exon 5 inclusion. Concomitant with T cell activation-induced exon 5 skipping, we observed a downregulation of SRSF1. Using RNA immunoprecipitation, we showed that in activated T cells, SRSF1 recruitment to the CD6 transcript is impaired by increased chromatin acetylation levels. We propose that upon T cell activation, SRSF1 becomes limiting, and its function in CD6 exon 5 splicing is countered by an increase in CD6 transcription, dependent on chromatin acetylation.
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Affiliation(s)
- Vânia G da Glória
- Grupo Regulação Genética, Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto 4150-180, Portugal
| | - Mafalda Martins de Araújo
- Grupo Activação Celular e Expressão Genética, Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto 4150-180, Portugal; Instituto de Investigação em Ciências da Vida e da Saude, Escola de Ciências da Saude, Universidade do Minho, Braga 4710-057, Portugal; ICVS/3B's Laboratório Associado, Braga/Guimarães 4806-909, Portugal
| | - Ana Mafalda Santos
- Grupo Activação Celular e Expressão Genética, Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto 4150-180, Portugal
| | - Rafaela Leal
- Grupo Regulação Genética, Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto 4150-180, Portugal
| | - Sérgio F de Almeida
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade Lisboa, Lisboa 1649-028, Portugal; and
| | - Alexandre M Carmo
- Grupo Activação Celular e Expressão Genética, Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto 4150-180, Portugal; Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, Porto 4050-313, Portugal
| | - Alexandra Moreira
- Grupo Regulação Genética, Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto 4150-180, Portugal;
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34
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Gupta SK, Chikne V, Eliaz D, Tkacz ID, Naboishchikov I, Carmi S, Waldman Ben-Asher H, Michaeli S. Two splicing factors carrying serine-arginine motifs, TSR1 and TSR1IP, regulate splicing, mRNA stability, and rRNA processing in Trypanosoma brucei. RNA Biol 2014; 11:715-31. [PMID: 24922194 DOI: 10.4161/rna.29143] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
In trypanosomes, mRNAs are processed by trans-splicing; in this process, a common exon, the spliced leader, is added to all mRNAs from a small RNA donor, the spliced leader RNA (SL RNA). However, little is known regarding how this process is regulated. In this study we investigated the function of two serine-arginine-rich proteins, TSR1 and TSR1IP, implicated in trans-splicing in Trypanosoma brucei. Depletion of these factors by RNAi suggested their role in both cis- and trans-splicing. Microarray was used to examine the transcriptome of the silenced cells. The level of hundreds of mRNAs was changed, suggesting that these proteins have a role in regulating only a subset of T. brucei mRNAs. Mass-spectrometry analyses of complexes associated with these proteins suggest that these factors function in mRNA stability, translation, and rRNA processing. We further demonstrate changes in the stability of mRNA as a result of depletion of the two TSR proteins. In addition, rRNA defects were observed under the depletion of U2AF35, TSR1, and TSR1IP, but not SF1, suggesting involvement of SR proteins in rRNA processing.
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Affiliation(s)
- Sachin Kumar Gupta
- The Mina and Everard Goodman Faculty of Life Sciences, and Advanced Materials and Nanotechnology Institute; Bar-Ilan University; Ramat-Gan, Israel
| | - Vaibhav Chikne
- The Mina and Everard Goodman Faculty of Life Sciences, and Advanced Materials and Nanotechnology Institute; Bar-Ilan University; Ramat-Gan, Israel
| | - Dror Eliaz
- The Mina and Everard Goodman Faculty of Life Sciences, and Advanced Materials and Nanotechnology Institute; Bar-Ilan University; Ramat-Gan, Israel
| | - Itai Dov Tkacz
- The Mina and Everard Goodman Faculty of Life Sciences, and Advanced Materials and Nanotechnology Institute; Bar-Ilan University; Ramat-Gan, Israel
| | - Ilana Naboishchikov
- The Mina and Everard Goodman Faculty of Life Sciences, and Advanced Materials and Nanotechnology Institute; Bar-Ilan University; Ramat-Gan, Israel
| | - Shai Carmi
- The Mina and Everard Goodman Faculty of Life Sciences, and Advanced Materials and Nanotechnology Institute; Bar-Ilan University; Ramat-Gan, Israel
| | - Hiba Waldman Ben-Asher
- The Mina and Everard Goodman Faculty of Life Sciences, and Advanced Materials and Nanotechnology Institute; Bar-Ilan University; Ramat-Gan, Israel
| | - Shulamit Michaeli
- The Mina and Everard Goodman Faculty of Life Sciences, and Advanced Materials and Nanotechnology Institute; Bar-Ilan University; Ramat-Gan, Israel
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35
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Qian W, Liu F. Regulation of alternative splicing of tau exon 10. Neurosci Bull 2014; 30:367-77. [PMID: 24627328 DOI: 10.1007/s12264-013-1411-2] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2013] [Accepted: 01/03/2014] [Indexed: 12/22/2022] Open
Abstract
The neuronal microtubule-associated protein tau is abnormally hyperphosphorylated and aggregated into neurofibrillary tangles in the brains of individuals with Alzheimer's disease and related neurodegenerative disorders. The adult human brain expresses six isoforms of tau generated by alternative splicing of exons 2, 3, and 10 of its pre-mRNA. Exon 10 encodes the second microtubule-binding repeat of tau. Its alternative splicing produces tau isoforms with either three or four microtubule-binding repeats, termed 3R-tau and 4Rtau. In the normal adult human brain, the level of 3R-tau is approximately equal to that of 4R-tau. Several silent and intronic mutations of the tau gene associated with FTDP-17T (frontotemporal dementia with Parkinsonism linked to chromosome 17 and specifically characterized by tau pathology) only disrupt exon 10 splicing, but do not influence the primary sequence of the tau protein. Thus, abnormal exon 10 splicing is sufficient to cause neurodegeneration and dementia. Here, we review the regulation of tau exon 10 splicing by cis-elements and trans-factors and summarize all the mutations associated with FTDP-17T and related tauopathies. The findings suggest that correction of exon 10 splicing may be a potential target for tau exon 10 splicing-related tauopathies.
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Affiliation(s)
- Wei Qian
- Department of Biochemistry and Molecular Biology, School of Medicine, Nantong University, Nantong, 226001, China
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36
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Kamoun M, Filali M, Murray MV, Awasthi S, Wadzinski BE. Protein phosphatase 2A family members (PP2A and PP6) associate with U1 snRNP and the spliceosome during pre-mRNA splicing. Biochem Biophys Res Commun 2013; 440:306-11. [PMID: 24064353 PMCID: PMC3891829 DOI: 10.1016/j.bbrc.2013.09.068] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2013] [Accepted: 09/13/2013] [Indexed: 11/23/2022]
Abstract
Protein phosphorylation and dephosphorylation are both important for multiple steps in the splicing pathway. Members of the PP1 and PP2A subfamilies of phospho-serine/threonine phosphatases play essential but redundant roles in the second step of the splicing reaction. PP6, a member of the PP2A subfamily, is the mammalian homolog of yeast Sit4p and ppe1, which are involved in cell cycle regulation; however, the involvement of PP6 in the splicing pathway remains unclear. Here we show that PP2A family members physically associate with the spliceosome throughout the splicing reaction. PP2A holoenzyme and PP6 were found stably associated with U1 snRNP. Together our findings indicate that these phosphatases regulate splicing catalysis involving U1 snRNP and suggest an important evolutionary conserved role of PP2A family phosphatases in pre-mRNA splicing.
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Affiliation(s)
- Malek Kamoun
- Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, Philadelphia, PA, USA.
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37
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Liu S, Cheng C. Alternative RNA splicing and cancer. WILEY INTERDISCIPLINARY REVIEWS. RNA 2013; 4:547-66. [PMID: 23765697 PMCID: PMC4426271 DOI: 10.1002/wrna.1178] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2013] [Revised: 05/10/2013] [Accepted: 05/11/2013] [Indexed: 01/04/2023]
Abstract
Alternative splicing of pre-messenger RNA (mRNA) is a fundamental mechanism by which a gene can give rise to multiple distinct mRNA transcripts, yielding protein isoforms with different, even opposing, functions. With the recognition that alternative splicing occurs in nearly all human genes, its relationship with cancer-associated pathways has emerged as a rapidly growing field. In this review, we summarize recent findings that have implicated the critical role of alternative splicing in cancer and discuss current understandings of the mechanisms underlying dysregulated alternative splicing in cancer cells.
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Affiliation(s)
- Sali Liu
- Department of Medicine, Robert H. Lurie Comprehensive Cancer Center, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
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38
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Montecucco A, Biamonti G. Pre-mRNA processing factors meet the DNA damage response. Front Genet 2013; 4:102. [PMID: 23761808 PMCID: PMC3674313 DOI: 10.3389/fgene.2013.00102] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2013] [Accepted: 05/20/2013] [Indexed: 12/04/2022] Open
Abstract
It is well-known that DNA-damaging agents induce genome instability, but only recently have we begun to appreciate that chromosomes are fragile per se and frequently subject to DNA breakage. DNA replication further magnifies such fragility, because it leads to accumulation of single-stranded DNA. Recent findings suggest that chromosome fragility is similarly increased during transcription. Transcripts produced by RNA polymerase II (RNAPII) are subject to multiple processing steps, including maturation of 5′ and 3′ ends and splicing, followed by transport to the cytoplasm. RNA maturation starts on nascent transcripts and is mediated by a number of diverse proteins and ribonucleoprotein particles some of which are recruited cotranscriptionally through interactions with the carboxy-terminal domain of RNAPII. This coupling is thought to maximize efficiency of pre-mRNA maturation and directly impacts the choice of alternative splice sites. Mounting evidence suggests that lack of coordination among different RNA maturation steps, by perturbing the interaction of nascent transcripts with the DNA template, has deleterious effects on genome stability. Thus, in the absence of proper surveillance mechanisms, transcription could be a major source of DNA damage in cancer. Recent high-throughput screenings in human cells and budding yeast have identified several factors implicated in RNA metabolism that are targets of DNA damage checkpoint kinases: ATM (ataxia telangiectasia mutated) and ATR (ATM-Rad3 related) (Tel1 and Mec1 in budding yeast, respectively). Moreover, inactivation of various RNA processing factors induces accumulation of γH2AX foci, an early sign of DNA damage. Thus, a complex network is emerging that links DNA repair and RNA metabolism. In this review we provide a comprehensive overview of the role played by pre-mRNA processing factors in the cell response to DNA damage and in the maintenance of genome stability.
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39
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Regulation of splicing by SR proteins and SR protein-specific kinases. Chromosoma 2013; 122:191-207. [PMID: 23525660 DOI: 10.1007/s00412-013-0407-z] [Citation(s) in RCA: 312] [Impact Index Per Article: 28.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2013] [Revised: 03/04/2013] [Accepted: 03/06/2013] [Indexed: 12/21/2022]
Abstract
Genomic sequencing reveals similar but limited numbers of protein-coding genes in different genomes, which begs the question of how organismal diversities are generated. Alternative pre-mRNA splicing, a widespread phenomenon in higher eukaryotic genomes, is thought to provide a mechanism to increase the complexity of the proteome and introduce additional layers for regulating gene expression in different cell types and during development. Among a large number of factors implicated in the splicing regulation are the SR protein family of splicing factors and SR protein-specific kinases. Here, we summarize the rules for SR proteins to function as splicing regulators, which depend on where they bind in exons versus intronic regions, on alternative exons versus flanking competing exons, and on cooperative as well as competitive binding between different SR protein family members on many of those locations. We review the importance of cycles of SR protein phosphorylation/dephosphorylation in the splicing reaction with emphasis on the recent molecular insight into the role of SR protein phosphorylation in early steps of spliceosome assembly. Finally, we highlight recent discoveries of SR protein-specific kinases in transducing growth signals to regulate alternative splicing in the nucleus and the connection of both SR proteins and SR protein kinases to human diseases, particularly cancer.
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40
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Roca X, Krainer AR, Eperon IC. Pick one, but be quick: 5' splice sites and the problems of too many choices. Genes Dev 2013; 27:129-44. [PMID: 23348838 DOI: 10.1101/gad.209759.112] [Citation(s) in RCA: 155] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Splice site selection is fundamental to pre-mRNA splicing and the expansion of genomic coding potential. 5' Splice sites (5'ss) are the critical elements at the 5' end of introns and are extremely diverse, as thousands of different sequences act as bona fide 5'ss in the human transcriptome. Most 5'ss are recognized by base-pairing with the 5' end of the U1 small nuclear RNA (snRNA). Here we review the history of research on 5'ss selection, highlighting the difficulties of establishing how base-pairing strength determines splicing outcomes. We also discuss recent work demonstrating that U1 snRNA:5'ss helices can accommodate noncanonical registers such as bulged duplexes. In addition, we describe the mechanisms by which other snRNAs, regulatory proteins, splicing enhancers, and the relative positions of alternative 5'ss contribute to selection. Moreover, we discuss mechanisms by which the recognition of numerous candidate 5'ss might lead to selection of a single 5'ss and propose that protein complexes propagate along the exon, thereby changing its physical behavior so as to affect 5'ss selection.
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Affiliation(s)
- Xavier Roca
- School of Biological Sciences, Division of Molecular Genetics and Cell Biology, Nanyang Technological University, Singapore.
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41
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Taliaferro JM, Marwha D, Aspden JL, Mavrici D, Cheng NE, Kohlstaedt LA, Rio DC. The Drosophila splicing factor PSI is phosphorylated by casein kinase II and tousled-like kinase. PLoS One 2013; 8:e56401. [PMID: 23437125 PMCID: PMC3577899 DOI: 10.1371/journal.pone.0056401] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2012] [Accepted: 12/28/2012] [Indexed: 12/27/2022] Open
Abstract
Alternative splicing of pre-mRNA is a highly regulated process that allows cells to change their genetic informational output. These changes are mediated by protein factors that directly bind specific pre-mRNA sequences. Although much is known about how these splicing factors regulate pre-mRNA splicing events, comparatively little is known about the regulation of the splicing factors themselves. Here, we show that the Drosophila splicing factor P element Somatic Inhibitor (PSI) is phosphorylated at at least two different sites by at minimum two different kinases, casein kinase II (CK II) and tousled-like kinase (tlk). These phosphorylation events may be important for regulating protein-protein interactions involving PSI. Additionally, we show that PSI interacts with several proteins in Drosophila S2 tissue culture cells, the majority of which are splicing factors.
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Affiliation(s)
- J. Matthew Taliaferro
- Department of Molecular and Cell Biology, University of California, Berkeley, California, United States of America
| | - Dhruv Marwha
- Department of Molecular and Cell Biology, University of California, Berkeley, California, United States of America
| | - Julie L. Aspden
- Department of Molecular and Cell Biology, University of California, Berkeley, California, United States of America
| | - Daniela Mavrici
- Department of Molecular and Cell Biology, University of California, Berkeley, California, United States of America
| | - Nathalie E. Cheng
- Department of Molecular and Cell Biology, University of California, Berkeley, California, United States of America
| | - Lori A. Kohlstaedt
- Department of Molecular and Cell Biology, University of California, Berkeley, California, United States of America
- California Institute for Quantitative Biosciences (QB3), University of California, Berkeley, California, United States of America
| | - Donald C. Rio
- Department of Molecular and Cell Biology, University of California, Berkeley, California, United States of America
- Center for Integrative Genomics, University of California, Berkeley, California, United States of America
- California Institute for Quantitative Biosciences (QB3), University of California, Berkeley, California, United States of America
- * E-mail:
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42
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Lee KM, Tarn WY. Coupling pre-mRNA processing to transcription on the RNA factory assembly line. RNA Biol 2013; 10:380-90. [PMID: 23392244 DOI: 10.4161/rna.23697] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
It has been well-documented that nuclear processing of primary transcripts of RNA polymerase II occurs co-transcriptionally and is functionally coupled to transcription. Moreover, increasing evidence indicates that transcription influences pre-mRNA splicing and even several post-splicing RNA processing events. In this review, we discuss the issues of how RNA polymerase II modulates co-transcriptional RNA processing events via its carboxyl terminal domain, and the protein domains involved in coupling of transcription and RNA processing events. In addition, we describe how transcription influences the expression or stability of mRNAs through the formation of distinct mRNP complexes. Finally, we delineate emerging findings that chromatin modifications function in the regulation of RNA processing steps, especially splicing, in addition to transcription. Overall, we provide a comprehensive view that transcription could integrate different control systems, from epigenetic to post-transcriptional control, for efficient gene expression.
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Affiliation(s)
- Kuo-Ming Lee
- Institute of Biomedical Sciences; Academia Sinica; Taipei, Taiwan
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43
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Abnormal expression of the pre-mRNA splicing regulators SRSF1, SRSF2, SRPK1 and SRPK2 in non small cell lung carcinoma. PLoS One 2012; 7:e46539. [PMID: 23071587 PMCID: PMC3468597 DOI: 10.1371/journal.pone.0046539] [Citation(s) in RCA: 111] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2012] [Accepted: 08/31/2012] [Indexed: 01/15/2023] Open
Abstract
Splicing abnormalities frequently occur in cancer. A key role as splice site choice regulator is played by the members of the SR (Ser/Arg-rich) family of proteins. We recently demonstrated that SRSF2 is involved in cisplatin-mediated apoptosis of human lung carcinoma cell lines. In this study, by using immunohistochemistry, we demonstrate that the SR proteins SRSF1 and SRSF2 are overexpressed in 63% and 65% of lung adenocarcinoma (ADC) as well as in 68% and 91% of squamous cell lung carcinoma (SCC), respectively, compared to normal lung epithelial cells. In addition, we show that SRSF2 overexpression correlates with high level of phosphorylated SRSF2 in both ADC (p<0.0001) and SCC (p = 0.02), indicating that SRSF2 mostly accumulates under a phosphorylated form in lung tumors. Consistently, we further show that the SR-phosphorylating kinases SRPK1 and SRPK2 are upregulated in 92% and 94% of ADC as well as in 72% and 68% of SCC, respectively. P-SRSF2 and SRPK2 scores are correlated in ADC (p = 0.01). Using lung adenocarcinoma cell lines, we demonstrate that SRSF1 overexpression leads to a more invasive phenotype, evidenced by activation of PI3K/AKT and p42/44MAPK signaling pathways, increased growth capacity in soft agar, acquisition of mesenchymal markers such as E cadherin loss, vimentin and fibronectin gain, and increased resistance to chemotherapies. Finally, we provide evidence that high levels of SRSF1 and P-SRSF2 proteins are associated with extensive stage (III–IV) in ADC. Taken together, these results indicate that a global deregulation of pre-mRNA splicing regulators occurs during lung tumorigenesis and does not predict same outcome in both Non Small Cell Lung Carcinoma histological sub-types, likely contributing to a more aggressive phenotype in adenocarcinoma.
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Risso G, Pelisch F, Quaglino A, Pozzi B, Srebrow A. Regulating the regulators: serine/arginine-rich proteins under scrutiny. IUBMB Life 2012; 64:809-16. [PMID: 22941908 DOI: 10.1002/iub.1075] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2012] [Accepted: 07/04/2012] [Indexed: 01/29/2023]
Abstract
Serine/arginine-rich (SR) proteins are among the most studied splicing regulators. They constitute a family of evolutionarily conserved proteins that, apart from their initially identified and deeply studied role in splicing regulation, have been implicated in genome stability, chromatin binding, transcription elongation, mRNA stability, mRNA export and mRNA translation. Remarkably, this list of SR protein activities seems far from complete, as unexpected functions keep being unraveled. An intriguing aspect that awaits further investigation is how the multiple tasks of SR proteins are concertedly regulated within mammalian cells. In this article, we first discuss recent findings regarding the regulation of SR protein expression, activity and accessibility. We dive into recent studies describing SR protein auto-regulatory feedback loops involving different molecular mechanisms such asunproductive splicing, microRNA-mediated regulation and translational repression. In addition, we take into account another step of regulation of SR proteins, presenting new findings about a variety of post-translational modifications by proteomics approaches and how some of these modifications can regulate SR protein sub-cellular localization or stability. Towards the end, we focus in two recently revealed functions of SR proteins beyond mRNA biogenesis and metabolism, the regulation of micro-RNA processing and the regulation of small ubiquitin-like modifier (SUMO) conjugation.
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Affiliation(s)
- Guillermo Risso
- Instituto de Fisiología, Biología Molecular y Neurociencias - Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina
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45
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Zou L, Zhang H, Du C, Liu X, Zhu S, Zhang W, Li Z, Gao C, Zhao X, Mei M, Bao S, Zheng H. Correlation of SRSF1 and PRMT1 expression with clinical status of pediatric acute lymphoblastic leukemia. J Hematol Oncol 2012; 5:42. [PMID: 22839530 PMCID: PMC3459738 DOI: 10.1186/1756-8722-5-42] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2012] [Accepted: 07/15/2012] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Acute lymphoblastic leukemia (ALL) is the most frequently-occurring malignant neoplasm in children, but the pathogenesis of the disease remains unclear. In a microarray assay using samples from 100 children with ALL, SFRS1 was found to be up-regulated. Serine/arginine-rich splicing factor 1 (SRSF1, also termed SF2/ASF), encoded by the SFRS1 gene, had been shown to be a pro-oncoprotein. Our previous study indicated that SRSF1 can be methylated by protein arginine methyltransferase 1 (PRMT1) in vitro; however, the biological function of SRSF1 and PRMT1 in pediatric ALL are presently unknown. METHODS Matched, newly diagnosed (ND), complete remission (CR) and relapse (RE) bone marrow samples from 57 patients were collected in order to evaluate the expression patterns of SRSF1 and PRMT1. The potential oncogenic mechanism of SRSF1 and PRMT1 in leukemogenesis was also investigated. RESULTS We identified significant up-regulation of SRSF1 and PRMT1 in the ND samples. Importantly, the expression of SRSF1 and PRMT1 returned to normal levels after CR, but rebounded in the RE samples. Our observation that SRSF1 could predict disease relapse was of particular interest, although the expression patterns of SRSF1 and PRMT1 were independent of the cytogenetic subtypes. In pre-B-cell lines, both SRSF1 and PRMT1 expression could be efficiently attenuated by the clinical chemotherapy agents arabinoside cytosine (Ara-c) or vincristine (VCR). Moreover, SRSF1 and PRMT1 were associated with each other in leukemia cells in vivo. Knock-down of SRSF1 resulted in an increase in early apoptosis, which could be further induced by chemotherapeutics. CONCLUSIONS Our results indicate that SRSF1 serves as an anti-apoptotic factor and potentially contributes to leukemogenesis in pediatric ALL patients by cooperating with PRMT1.
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Affiliation(s)
- Limin Zou
- Hematology Oncology Center, Beijing Key Laboratory of Pediatric Hematology Oncology, National Key Discipline of Pediatrics, Beijing Children's Hospital, Capital Medical University, 56 Nanlishi Road, Beijing 100045, China
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46
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Alternative Splicing of Fibroblast Growth Factor Receptor IgIII Loops in Cancer. J Nucleic Acids 2011; 2012:950508. [PMID: 22203889 PMCID: PMC3238399 DOI: 10.1155/2012/950508] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2011] [Revised: 07/27/2011] [Accepted: 08/07/2011] [Indexed: 02/06/2023] Open
Abstract
Alternative splicing
of the IgIII loop of fibroblast growth factor
receptors (FGFRs) 1–3 produces b- and
c-variants of the receptors with distinctly
different biological impact based on their
distinct ligand-binding spectrum. Tissue-specific expression of these splice variants
regulates interactions in embryonic development,
tissue maintenance and repair, and cancer.
Alterations in FGFR2 splicing are involved in
epithelial mesenchymal transition that produces
invasive, metastatic features during tumor
progression.
Recent research has elucidated regulatory factors that determine
the splice choice both on the level of exogenous signaling events
and on the RNA-protein interaction level. Moreover, methodology
has been developed that will enable the in depth analysis of
splicing events during tumorigenesis and provide further insight on
the role of FGFR 1–3 IIIb and IIIc in the pathophysiology of
various malignancies. This paper aims to summarize expression
patterns in various tumor types and outlines possibilities for
further analysis and application.
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47
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Jilkine A, Angenent SB, Wu LF, Altschuler SJ. A density-dependent switch drives stochastic clustering and polarization of signaling molecules. PLoS Comput Biol 2011; 7:e1002271. [PMID: 22102805 PMCID: PMC3213192 DOI: 10.1371/journal.pcbi.1002271] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2011] [Accepted: 09/26/2011] [Indexed: 01/03/2023] Open
Abstract
Positive feedback plays a key role in the ability of signaling molecules to form highly localized clusters in the membrane or cytosol of cells. Such clustering can occur in the absence of localizing mechanisms such as pre-existing spatial cues, diffusional barriers, or molecular cross-linking. What prevents positive feedback from amplifying inevitable biological noise when an un-clustered "off" state is desired? And, what limits the spread of clusters when an "on" state is desired? Here, we show that a minimal positive feedback circuit provides the general principle for both suppressing and amplifying noise: below a critical density of signaling molecules, clustering switches off; above this threshold, highly localized clusters are recurrently generated. Clustering occurs only in the stochastic regime, suggesting that finite sizes of molecular populations cannot be ignored in signal transduction networks. The emergence of a dominant cluster for finite numbers of molecules is partly a phenomenon of random sampling, analogous to the fixation or loss of neutral mutations in finite populations. We refer to our model as the "neutral drift polarity model." Regulating the density of signaling molecules provides a simple mechanism for a positive feedback circuit to robustly switch between clustered and un-clustered states. The intrinsic ability of positive feedback both to create and suppress clustering is a general mechanism that could operate within diverse biological networks to create dynamic spatial organization.
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Affiliation(s)
- Alexandra Jilkine
- Molecular and Cellular Biology, University of Arizona, Tucson, Arizona, United States of America
- Green Center for Systems Biology and Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Sigurd B. Angenent
- Mathematics Department, University of Wisconsin, Madison, Wisconsin, United States of America
- * E-mail: (SBA); (LFW); (SJA)
| | - Lani F. Wu
- Green Center for Systems Biology and Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
- * E-mail: (SBA); (LFW); (SJA)
| | - Steven J. Altschuler
- Green Center for Systems Biology and Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
- * E-mail: (SBA); (LFW); (SJA)
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48
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Eto K, Sonoda Y, Abe SI. The kinase DYRKIA regulates pre-mRNA splicing in spermatogonia and proliferation of spermatogonia and Sertoli cells by phosphorylating a spliceosomal component, SAP155, in postnatal murine testes. Mol Cell Biochem 2011; 355:217-22. [PMID: 21553260 DOI: 10.1007/s11010-011-0857-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2011] [Accepted: 04/20/2011] [Indexed: 10/18/2022]
Abstract
SAP155 is an essential component of the spliceosome and its phosphorylation is required for splicing catalysis, but little is known concerning its function and regulation during spermatogenesis in postnatal murine testes. We report that inhibition of dual-specificity tyrosine-phosphorylation regulated kinase (DYRK) IA strongly suppressed the mitogen-stimulated SAP155 phosphorylation and constitutive splicing of IκB pre-mRNA as well as the proliferation of spermatogonial and Sertoli cells in cultures of the 6-day post partum testes and a spermatogonial cell line, but not in a Sertoli cell line. Our findings suggest that the active spliceosome, containing SAP155 phosphorylated by DYRKIA, performs pre-mRNA splicing in spermatogonia during testicular development.
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Affiliation(s)
- Ko Eto
- Department of Biological Sciences, Graduate School of Science and Technology, Kumamoto University, Kumamoto 860-8555, Japan.
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49
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Qian W, Liang H, Shi J, Jin N, Grundke-Iqbal I, Iqbal K, Gong CX, Liu F. Regulation of the alternative splicing of tau exon 10 by SC35 and Dyrk1A. Nucleic Acids Res 2011; 39:6161-71. [PMID: 21470964 PMCID: PMC3152345 DOI: 10.1093/nar/gkr195] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2010] [Revised: 03/16/2011] [Accepted: 03/17/2011] [Indexed: 12/16/2022] Open
Abstract
Abnormal alternative splicing of tau exon 10 results in imbalance of 3R-tau and 4R-tau expression, which is sufficient to cause neurofibrillary degeneration. Splicing factor SC35, a member of the superfamily of the serine/arginine-rich (SR) proteins, promotes tau exon 10 inclusion. The molecular mechanism by which SC35 participates in tau exon 10 splicing remains elusive. In the present study, we found that tau pre-mRNA was coprecipitated by SC35 tagged with HA. Mutation of the SC35-like exonic splicing enhancer located at exon 10 of tau affected both the binding of SC35 to tau pre-mRNA and promotion of tau exon 10 inclusion, suggesting that SC35 acts on the SC35-like exonic splicing enhancer to promote tau exon 10 inclusion. Dyrk1A (dual-specificity tyrosine-phosphorylated and regulated kinase 1A) phosphorylated SC35 in vitro and interacted with it in cultured cells. Overexpression of Dyrk1A suppressed SC35's ability to promote tau exon 10 inclusion. Downregulation of Dyrk1A promoted 4R-tau expression. Therefore, upregulation of Dyrk1A in Down syndrome brain or Alzheimer's brain may cause dysregulation of tau exon 10 splicing through SC35, and probably together with other splicing factors, leading to the imbalance in 3R-tau and 4R-tau expression, which may initiate or accelerate tau pathology and cause neurofibrillary degeneration in the diseases.
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Affiliation(s)
- Wei Qian
- Jiangsu Key Laboratory of Neuroregeneration, Department of Biochemistry, Medical School, Nantong University, Nantong, Jiangsu, P. R. China and Department of Neurochemistry, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, NY, USA
| | - Hongwei Liang
- Jiangsu Key Laboratory of Neuroregeneration, Department of Biochemistry, Medical School, Nantong University, Nantong, Jiangsu, P. R. China and Department of Neurochemistry, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, NY, USA
| | - Jianhua Shi
- Jiangsu Key Laboratory of Neuroregeneration, Department of Biochemistry, Medical School, Nantong University, Nantong, Jiangsu, P. R. China and Department of Neurochemistry, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, NY, USA
| | - Nana Jin
- Jiangsu Key Laboratory of Neuroregeneration, Department of Biochemistry, Medical School, Nantong University, Nantong, Jiangsu, P. R. China and Department of Neurochemistry, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, NY, USA
| | - Inge Grundke-Iqbal
- Jiangsu Key Laboratory of Neuroregeneration, Department of Biochemistry, Medical School, Nantong University, Nantong, Jiangsu, P. R. China and Department of Neurochemistry, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, NY, USA
| | - Khalid Iqbal
- Jiangsu Key Laboratory of Neuroregeneration, Department of Biochemistry, Medical School, Nantong University, Nantong, Jiangsu, P. R. China and Department of Neurochemistry, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, NY, USA
| | - Cheng-Xin Gong
- Jiangsu Key Laboratory of Neuroregeneration, Department of Biochemistry, Medical School, Nantong University, Nantong, Jiangsu, P. R. China and Department of Neurochemistry, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, NY, USA
| | - Fei Liu
- Jiangsu Key Laboratory of Neuroregeneration, Department of Biochemistry, Medical School, Nantong University, Nantong, Jiangsu, P. R. China and Department of Neurochemistry, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, NY, USA
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Ghigna C, Valacca C, Biamonti G. Alternative splicing and tumor progression. Curr Genomics 2011; 9:556-70. [PMID: 19516963 PMCID: PMC2694562 DOI: 10.2174/138920208786847971] [Citation(s) in RCA: 133] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2008] [Revised: 08/12/2008] [Accepted: 08/18/2008] [Indexed: 12/15/2022] Open
Abstract
Alternative splicing is a key molecular mechanism for increasing the functional diversity of the eukaryotic proteomes. A large body of experimental data implicates aberrant splicing in various human diseases, including cancer. Both mutations in cis-acting splicing elements and alterations in the expression and/or activity of splicing regulatory factors drastically affect the splicing profile of many cancer-associated genes. In addition, the splicing profile of several cancer-associated genes is altered in particular types of cancer arguing for a direct role of specific splicing isoforms in tumor progression. Deciphering the mechanisms underlying aberrant splicing in cancer may prove crucial to understand how splicing machinery is controlled and integrated with other cellular processes, in particular transcription and signaling pathways. Moreover, the characterization of splicing deregulation in cancer will lead to a better comprehension of malignant transformation. Cancer-associated alternative splicing variants may be new tools for the diagnosis and classification of cancers and could be the targets for innovative therapeutical interventions based on highly selective splicing correction approaches.
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Affiliation(s)
- Claudia Ghigna
- Istituto di Genetica Molecolare - Consiglio Nazionale delle Ricerche, Via Abbiategrasso 207. 27100 Pavia, Italy
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