1
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Korhonen PK, Wang T, Young ND, Byrne JJ, Campos TL, Chang BC, Taki AC, Gasser RB. Analysis of Haemonchus embryos at single cell resolution identifies two eukaryotic elongation factors as intervention target candidates. Comput Struct Biotechnol J 2024; 23:1026-1035. [PMID: 38435301 PMCID: PMC10907403 DOI: 10.1016/j.csbj.2024.01.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2023] [Revised: 01/14/2024] [Accepted: 01/15/2024] [Indexed: 03/05/2024] Open
Abstract
Advances in single cell technologies are allowing investigations of a wide range of biological processes and pathways in animals, such as the multicellular model organism Caenorhabditis elegans - a free-living nematode. However, there has been limited application of such technology to related parasitic nematodes which cause major diseases of humans and animals worldwide. With no vaccines against the vast majority of parasitic nematodes and treatment failures due to drug resistance or inefficacy, new intervention targets are urgently needed, preferably informed by a deep understanding of these nematodes' cellular and molecular biology - which is presently lacking for most worms. Here, we created the first single cell atlas for an early developmental stage of Haemonchus contortus - a highly pathogenic, C. elegans-related parasitic nematode. We obtained and curated RNA sequence (snRNA-seq) data from single nuclei from embryonating eggs of H. contortus (150,000 droplets), and selected high-quality transcriptomic data for > 14,000 single nuclei for analysis, and identified 19 distinct clusters of cells. Guided by comparative analyses with C. elegans, we were able to reproducibly assign seven cell clusters to body wall muscle, hypodermis, neuronal, intestinal or seam cells, and identified eight genes that were transcribed in all cell clusters/types, three of which were inferred to be essential in H. contortus. Two of these genes (i.e. Hc-eef-1A and Hc-eef1G), coding for eukaryotic elongation factors (called Hc-eEF1A and Hc-eEF1G), were also demonstrated to be transcribed and expressed in all key developmental stages of H. contortus. Together with these findings, sequence- and structure-based comparative analyses indicated the potential of Hc-eEF1A and/or Hc-eEF1G as intervention targets within the protein biosynthesis machinery of H. contortus. Future work will focus on single cell studies of all key developmental stages and tissues of H. contortus, and on evaluating the suitability of the two elongation factor proteins as drug targets in H. contortus and related nematodes, with a view to finding new nematocidal drug candidates.
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Affiliation(s)
- Pasi K. Korhonen
- Department of Veterinary Biosciences, Melbourne Veterinary School, Faculty of Science, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Tao Wang
- Department of Veterinary Biosciences, Melbourne Veterinary School, Faculty of Science, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Neil D. Young
- Department of Veterinary Biosciences, Melbourne Veterinary School, Faculty of Science, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Joseph J. Byrne
- Department of Veterinary Biosciences, Melbourne Veterinary School, Faculty of Science, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Tulio L. Campos
- Department of Veterinary Biosciences, Melbourne Veterinary School, Faculty of Science, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Bill C.H. Chang
- Department of Veterinary Biosciences, Melbourne Veterinary School, Faculty of Science, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Aya C. Taki
- Department of Veterinary Biosciences, Melbourne Veterinary School, Faculty of Science, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Robin B. Gasser
- Department of Veterinary Biosciences, Melbourne Veterinary School, Faculty of Science, The University of Melbourne, Parkville, Victoria 3010, Australia
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2
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Ni Z, Ahmed N, Nabeel-Shah S, Guo X, Pu S, Song J, Marcon E, Burke G, Tong AH, Chan K, Ha KH, Blencowe B, Moffat J, Greenblatt J. Identifying human pre-mRNA cleavage and polyadenylation factors by genome-wide CRISPR screens using a dual fluorescence readthrough reporter. Nucleic Acids Res 2024; 52:4483-4501. [PMID: 38587191 PMCID: PMC11077057 DOI: 10.1093/nar/gkae240] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2023] [Revised: 01/29/2024] [Accepted: 04/02/2024] [Indexed: 04/09/2024] Open
Abstract
Messenger RNA precursors (pre-mRNA) generally undergo 3' end processing by cleavage and polyadenylation (CPA), which is specified by a polyadenylation site (PAS) and adjacent RNA sequences and regulated by a large variety of core and auxiliary CPA factors. To date, most of the human CPA factors have been discovered through biochemical and proteomic studies. However, genetic identification of the human CPA factors has been hampered by the lack of a reliable genome-wide screening method. We describe here a dual fluorescence readthrough reporter system with a PAS inserted between two fluorescent reporters. This system enables measurement of the efficiency of 3' end processing in living cells. Using this system in combination with a human genome-wide CRISPR/Cas9 library, we conducted a screen for CPA factors. The screens identified most components of the known core CPA complexes and other known CPA factors. The screens also identified CCNK/CDK12 as a potential core CPA factor, and RPRD1B as a CPA factor that binds RNA and regulates the release of RNA polymerase II at the 3' ends of genes. Thus, this dual fluorescence reporter coupled with CRISPR/Cas9 screens reliably identifies bona fide CPA factors and provides a platform for investigating the requirements for CPA in various contexts.
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Affiliation(s)
- Zuyao Ni
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, 160 College Street, Toronto, ON M5S 3E1, Canada
| | - Nujhat Ahmed
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, 160 College Street, Toronto, ON M5S 3E1, Canada
- Department of Molecular Genetics, University of Toronto, 1 King's College Circle, Toronto, ON M5A 1A8, Canada
| | - Syed Nabeel-Shah
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, 160 College Street, Toronto, ON M5S 3E1, Canada
- Department of Molecular Genetics, University of Toronto, 1 King's College Circle, Toronto, ON M5A 1A8, Canada
| | - Xinghua Guo
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, 160 College Street, Toronto, ON M5S 3E1, Canada
| | - Shuye Pu
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, 160 College Street, Toronto, ON M5S 3E1, Canada
| | - Jingwen Song
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, 160 College Street, Toronto, ON M5S 3E1, Canada
| | - Edyta Marcon
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, 160 College Street, Toronto, ON M5S 3E1, Canada
| | - Giovanni L Burke
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, 160 College Street, Toronto, ON M5S 3E1, Canada
- Department of Molecular Genetics, University of Toronto, 1 King's College Circle, Toronto, ON M5A 1A8, Canada
| | - Amy Hin Yan Tong
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, 160 College Street, Toronto, ON M5S 3E1, Canada
- Department of Molecular Genetics, University of Toronto, 1 King's College Circle, Toronto, ON M5A 1A8, Canada
- Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, ON Canada
| | - Katherine Chan
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, 160 College Street, Toronto, ON M5S 3E1, Canada
- Department of Molecular Genetics, University of Toronto, 1 King's College Circle, Toronto, ON M5A 1A8, Canada
- Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, ON Canada
| | - Kevin C H Ha
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, 160 College Street, Toronto, ON M5S 3E1, Canada
- Department of Molecular Genetics, University of Toronto, 1 King's College Circle, Toronto, ON M5A 1A8, Canada
| | - Benjamin J Blencowe
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, 160 College Street, Toronto, ON M5S 3E1, Canada
- Department of Molecular Genetics, University of Toronto, 1 King's College Circle, Toronto, ON M5A 1A8, Canada
| | - Jason Moffat
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, 160 College Street, Toronto, ON M5S 3E1, Canada
- Department of Molecular Genetics, University of Toronto, 1 King's College Circle, Toronto, ON M5A 1A8, Canada
- Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, ON Canada
- Institute for Biomaterials and Biomedical Engineering, University of Toronto, Toronto, ON Canada
| | - Jack F Greenblatt
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, 160 College Street, Toronto, ON M5S 3E1, Canada
- Department of Molecular Genetics, University of Toronto, 1 King's College Circle, Toronto, ON M5A 1A8, Canada
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3
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Russo M, Piccolo V, Polizzese D, Prosperini E, Borriero C, Polletti S, Bedin F, Marenda M, Michieletto D, Mandana GM, Rodighiero S, Cuomo A, Natoli G. Restrictor synergizes with Symplekin and PNUTS to terminate extragenic transcription. Genes Dev 2023; 37:1017-1040. [PMID: 38092518 PMCID: PMC10760643 DOI: 10.1101/gad.351057.123] [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: 08/08/2023] [Accepted: 11/29/2023] [Indexed: 12/28/2023]
Abstract
Transcription termination pathways mitigate the detrimental consequences of unscheduled promiscuous initiation occurring at hundreds of thousands of genomic cis-regulatory elements. The Restrictor complex, composed of the Pol II-interacting protein WDR82 and the RNA-binding protein ZC3H4, suppresses processive transcription at thousands of extragenic sites in mammalian genomes. Restrictor-driven termination does not involve nascent RNA cleavage, and its interplay with other termination machineries is unclear. Here we show that efficient termination at Restrictor-controlled extragenic transcription units involves the recruitment of the protein phosphatase 1 (PP1) regulatory subunit PNUTS, a negative regulator of the SPT5 elongation factor, and Symplekin, a protein associated with RNA cleavage complexes but also involved in cleavage-independent and phosphatase-dependent termination of noncoding RNAs in yeast. PNUTS and Symplekin act synergistically with, but independently from, Restrictor to dampen processive extragenic transcription. Moreover, the presence of limiting nuclear levels of Symplekin imposes a competition for its recruitment among multiple transcription termination machineries, resulting in mutual regulatory interactions. Hence, by synergizing with Restrictor, Symplekin and PNUTS enable efficient termination of processive, long-range extragenic transcription.
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Affiliation(s)
- Marta Russo
- Department of Experimental Oncology, European Institute of Oncology (IEO), Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Milan I-20139, Italy
| | - Viviana Piccolo
- Department of Experimental Oncology, European Institute of Oncology (IEO), Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Milan I-20139, Italy
| | - Danilo Polizzese
- Department of Experimental Oncology, European Institute of Oncology (IEO), Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Milan I-20139, Italy
| | - Elena Prosperini
- Department of Experimental Oncology, European Institute of Oncology (IEO), Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Milan I-20139, Italy
| | - Carolina Borriero
- Department of Experimental Oncology, European Institute of Oncology (IEO), Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Milan I-20139, Italy
| | - Sara Polletti
- Department of Experimental Oncology, European Institute of Oncology (IEO), Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Milan I-20139, Italy
| | - Fabio Bedin
- Department of Experimental Oncology, European Institute of Oncology (IEO), Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Milan I-20139, Italy
| | - Mattia Marenda
- Department of Experimental Oncology, European Institute of Oncology (IEO), Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Milan I-20139, Italy
| | - Davide Michieletto
- School of Physics and Astronomy, University of Edinburgh, Edinburgh EH9 3FD, United Kingdom
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of Edinburgh, Edinburgh EH4 2XU, United Kingdom
| | - Gaurav Madappa Mandana
- Department of Experimental Oncology, European Institute of Oncology (IEO), Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Milan I-20139, Italy
| | - Simona Rodighiero
- Department of Experimental Oncology, European Institute of Oncology (IEO), Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Milan I-20139, Italy
| | - Alessandro Cuomo
- Department of Experimental Oncology, European Institute of Oncology (IEO), Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Milan I-20139, Italy
| | - Gioacchino Natoli
- Department of Experimental Oncology, European Institute of Oncology (IEO), Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Milan I-20139, Italy;
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4
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Jia R, Zheng ZM. Oncogenic SRSF3 in health and diseases. Int J Biol Sci 2023; 19:3057-3076. [PMID: 37416784 PMCID: PMC10321290 DOI: 10.7150/ijbs.83368] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Accepted: 05/30/2023] [Indexed: 07/08/2023] Open
Abstract
Serine/arginine rich splicing factor 3 (SRSF3) is an important multi-functional splicing factor, and has attracted increasing attentions in the past thirty years. The importance of SRSF3 is evidenced by its impressively conserved protein sequences in all animals and alternative exon 4 which represents an autoregulatory mechanism to maintain its proper cellular expression level. New functions of SRSF3 have been continuously discovered recently, especially its oncogenic function. SRSF3 plays essential roles in many cellular processes by regulating almost all aspects of RNA biogenesis and processing of many target genes, and thus, contributes to tumorigenesis when overexpressed or disregulated. This review updates and highlights the gene, mRNA, and protein structure of SRSF3, the regulatory mechanisms of SRSF3 expression, and the characteristics of SRSF3 targets and binding sequences that contribute to SRSF3's diverse molecular and cellular functions in tumorigenesis and human diseases.
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Affiliation(s)
- Rong Jia
- The State Key Laboratory Breeding Base of Basic Science of Stomatology & Key Laboratory of Oral Biomedicine Ministry of Education, School & Hospital of Stomatology, Wuhan University, Wuhan, Hubei, China
| | - Zhi-Ming Zheng
- Tumor Virus RNA Biology Section, HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, Maryland, USA
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5
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Urso SJ, Sathaseevan A, Brent Derry W, Lamitina T. Regulation of the hypertonic stress response by the 3' mRNA cleavage and polyadenylation complex. Genetics 2023; 224:iyad051. [PMID: 36972377 PMCID: PMC10490458 DOI: 10.1093/genetics/iyad051] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Revised: 03/10/2023] [Accepted: 03/10/2023] [Indexed: 03/29/2023] Open
Abstract
Maintenance of osmotic homeostasis is one of the most aggressively defended homeostatic set points in physiology. One major mechanism of osmotic homeostasis involves the upregulation of proteins that catalyze the accumulation of solutes called organic osmolytes. To better understand how osmolyte accumulation proteins are regulated, we conducted a forward genetic screen in Caenorhabditis elegans for mutants with no induction of osmolyte biosynthesis gene expression (Nio mutants). The nio-3 mutant encoded a missense mutation in cpf-2/CstF64, while the nio-7 mutant encoded a missense mutation in symk-1/Symplekin. Both cpf-2 and symk-1 are nuclear components of the highly conserved 3' mRNA cleavage and polyadenylation complex. cpf-2 and symk-1 block the hypertonic induction of gpdh-1 and other osmotically induced mRNAs, suggesting they act at the transcriptional level. We generated a functional auxin-inducible degron (AID) allele for symk-1 and found that acute, post-developmental degradation in the intestine and hypodermis was sufficient to cause the Nio phenotype. symk-1 and cpf-2 exhibit genetic interactions that strongly suggest they function through alterations in 3' mRNA cleavage and/or alternative polyadenylation. Consistent with this hypothesis, we find that inhibition of several other components of the mRNA cleavage complex also cause a Nio phenotype. cpf-2 and symk-1 specifically affect the osmotic stress response since heat shock-induced upregulation of a hsp-16.2::GFP reporter is normal in these mutants. Our data suggest a model in which alternative polyadenylation of 1 or more mRNAs is essential to regulate the hypertonic stress response.
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Affiliation(s)
- Sarel J Urso
- Graduate Program in Cell Biology and Molecular Physiology, University of Pittsburgh Medical Center, Pittsburgh, PA 15261, USA
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA
| | - Anson Sathaseevan
- Developmental and Stem Cell Biology Program, Peter Gilgan Centre for Research and Learning, The Hospital for Sick Children, Toronto, ON M5G 0A4, Canada
| | - W Brent Derry
- Developmental and Stem Cell Biology Program, Peter Gilgan Centre for Research and Learning, The Hospital for Sick Children, Toronto, ON M5G 0A4, Canada
| | - Todd Lamitina
- Graduate Program in Cell Biology and Molecular Physiology, University of Pittsburgh Medical Center, Pittsburgh, PA 15261, USA
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA
- Division of Child Neurology, Department of Pediatrics, Children's Hospital of Pittsburgh, University of Pittsburgh Medical Center, Pittsburgh, PA 15224, USA
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6
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Sewell AK, Poss ZC, Ebmeier CC, Jacobsen JR, Old WM, Han M. The TORC1 phosphoproteome in C. elegans reveals roles in transcription and autophagy. iScience 2022; 25:104186. [PMID: 35479415 PMCID: PMC9036118 DOI: 10.1016/j.isci.2022.104186] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Revised: 03/14/2022] [Accepted: 03/29/2022] [Indexed: 11/13/2022] Open
Abstract
The protein kinase complex target of rapamycin complex 1 (TORC1) is a critical mediator of nutrient sensing that has been widely studied in cultured cells and yeast, yet our understanding of the regulatory activities of TORC1 in the context of a whole, multi-cellular organism is still very limited. Using Caenorhabditis elegans, we analyzed the DAF-15/Raptor-dependent phosphoproteome by quantitative mass spectrometry and characterized direct kinase targets by in vitro kinase assays. Here, we show new targets of TORC1 that indicate previously unknown regulation of transcription and autophagy. Our results further show that DAF-15/Raptor is differentially expressed during postembryonic development, suggesting a dynamic role for TORC1 signaling throughout the life span. This study provides a comprehensive view of the TORC1 phosphoproteome, reveals more than 100 DAF-15/Raptor-dependent phosphosites that reflect the complex function of TORC1 in a whole, multi-cellular organism, and serves as a rich resource to the field.
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Affiliation(s)
- Aileen K. Sewell
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, CO 80309-0347, USA
| | - Zachary C. Poss
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, CO 80309-0347, USA
| | - Christopher C. Ebmeier
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, CO 80309-0347, USA
| | - Jeremy R. Jacobsen
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, CO 80309-0347, USA
| | - William M. Old
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, CO 80309-0347, USA
| | - Min Han
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, CO 80309-0347, USA
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7
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Zhang M, Zhou J, Jiao L, Xu L, Hou L, Yin B, Qiang B, Lu S, Shu P, Peng X. Long Non-coding RNA T-uc.189 Modulates Neural Progenitor Cell Fate by Regulating Srsf3 During Mouse Cerebral Cortex Development. Front Neurosci 2021; 15:709684. [PMID: 34354569 PMCID: PMC8329457 DOI: 10.3389/fnins.2021.709684] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Accepted: 06/28/2021] [Indexed: 11/29/2022] Open
Abstract
Neurogenesis is a complex process that depends on the delicate regulation of spatial and temporal gene expression. In our previous study, we found that transcribed ultra-conserved regions (T-UCRs), a class of long non-coding RNAs that contain UCRs, are expressed in the developing nervous systems of mice, rhesus monkeys, and humans. In this study, we first detected the full-length sequence of T-uc.189, revealing that it was mainly concentrated in the ventricular zone (VZ) and that its expression decreased as the brain matured. Moreover, we demonstrated that knockdown of T-uc.189 inhibited neurogenesis. In addition, we found that T-uc.189 positively regulated the expression of serine-arginine-rich splicing factor 3 (Srsf3). Taken together, our results are the first to demonstrate that T-uc.189 regulates the expression of Srsf3 to maintain normal neurogenesis during cortical development.
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Affiliation(s)
- Meng Zhang
- Institute of Medical Biology, Chinese Academy of Medical Sciences, and Peking Union Medical College, Kunming, China
| | - Junjie Zhou
- The State Key Laboratory of Medical Molecular Biology, Department of Molecular Biology and Biochemistry, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Li Jiao
- Institute of Medical Biology, Chinese Academy of Medical Sciences, and Peking Union Medical College, Kunming, China
| | - Longjiang Xu
- Institute of Medical Biology, Chinese Academy of Medical Sciences, and Peking Union Medical College, Kunming, China
| | - Lin Hou
- The State Key Laboratory of Medical Molecular Biology, Department of Molecular Biology and Biochemistry, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Bin Yin
- The State Key Laboratory of Medical Molecular Biology, Department of Molecular Biology and Biochemistry, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Boqin Qiang
- The State Key Laboratory of Medical Molecular Biology, Department of Molecular Biology and Biochemistry, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Shuaiyao Lu
- Institute of Medical Biology, Chinese Academy of Medical Sciences, and Peking Union Medical College, Kunming, China
| | - Pengcheng Shu
- The State Key Laboratory of Medical Molecular Biology, Department of Molecular Biology and Biochemistry, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Xiaozhong Peng
- Institute of Medical Biology, Chinese Academy of Medical Sciences, and Peking Union Medical College, Kunming, China.,The State Key Laboratory of Medical Molecular Biology, Department of Molecular Biology and Biochemistry, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
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8
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Mehterov N, Kazakova M, Sbirkov Y, Vladimirov B, Belev N, Yaneva G, Todorova K, Hayrabedyan S, Sarafian V. Alternative RNA Splicing-The Trojan Horse of Cancer Cells in Chemotherapy. Genes (Basel) 2021; 12:genes12071085. [PMID: 34356101 PMCID: PMC8306420 DOI: 10.3390/genes12071085] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 07/14/2021] [Accepted: 07/15/2021] [Indexed: 12/12/2022] Open
Abstract
Almost all transcribed human genes undergo alternative RNA splicing, which increases the diversity of the coding and non-coding cellular landscape. The resultant gene products might have distinctly different and, in some cases, even opposite functions. Therefore, the abnormal regulation of alternative splicing plays a crucial role in malignant transformation, development, and progression, a fact supported by the distinct splicing profiles identified in both healthy and tumor cells. Drug resistance, resulting in treatment failure, still remains a major challenge for current cancer therapy. Furthermore, tumor cells often take advantage of aberrant RNA splicing to overcome the toxicity of the administered chemotherapeutic agents. Thus, deciphering the alternative RNA splicing variants in tumor cells would provide opportunities for designing novel therapeutics combating cancer more efficiently. In the present review, we provide a comprehensive outline of the recent findings in alternative splicing in the most common neoplasms, including lung, breast, prostate, head and neck, glioma, colon, and blood malignancies. Molecular mechanisms developed by cancer cells to promote oncogenesis as well as to evade anticancer drug treatment and the subsequent chemotherapy failure are also discussed. Taken together, these findings offer novel opportunities for future studies and the development of targeted therapy for cancer-specific splicing variants.
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Affiliation(s)
- Nikolay Mehterov
- Department of Medical Biology, Medical University-Plovdiv, 4002 Plovdiv, Bulgaria; (N.M.); (M.K.); (Y.S.)
- Research Institute, Medical University-Plovdiv, 4002 Plovdiv, Bulgaria
| | - Maria Kazakova
- Department of Medical Biology, Medical University-Plovdiv, 4002 Plovdiv, Bulgaria; (N.M.); (M.K.); (Y.S.)
- Research Institute, Medical University-Plovdiv, 4002 Plovdiv, Bulgaria
| | - Yordan Sbirkov
- Department of Medical Biology, Medical University-Plovdiv, 4002 Plovdiv, Bulgaria; (N.M.); (M.K.); (Y.S.)
- Research Institute, Medical University-Plovdiv, 4002 Plovdiv, Bulgaria
| | - Boyan Vladimirov
- Department of Maxillofacial Surgery, Medical University-Plovdiv, 4002 Plovdiv, Bulgaria;
| | - Nikolay Belev
- Medical Simulation and Training Center, Medical University-Plovdiv, 4002 Plovdiv, Bulgaria;
| | - Galina Yaneva
- Department of Biology, Faculty of Pharmacy, Medical University of Varna, 9002 Varna, Bulgaria;
| | - Krassimira Todorova
- Laboratory of Reproductive OMICs Technologies, Institute of Biology and Immunology of Reproduction, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria; (K.T.); (S.H.)
| | - Soren Hayrabedyan
- Laboratory of Reproductive OMICs Technologies, Institute of Biology and Immunology of Reproduction, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria; (K.T.); (S.H.)
| | - Victoria Sarafian
- Department of Medical Biology, Medical University-Plovdiv, 4002 Plovdiv, Bulgaria; (N.M.); (M.K.); (Y.S.)
- Research Institute, Medical University-Plovdiv, 4002 Plovdiv, Bulgaria
- Correspondence: ; Tel.: +359-882-512-952
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9
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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: 38] [Impact Index Per Article: 9.5] [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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10
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Zhou Z, Gong Q, Lin Z, Wang Y, Li M, Wang L, Ding H, Li P. Emerging Roles of SRSF3 as a Therapeutic Target for Cancer. Front Oncol 2020; 10:577636. [PMID: 33072610 PMCID: PMC7544984 DOI: 10.3389/fonc.2020.577636] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Accepted: 08/28/2020] [Indexed: 12/14/2022] Open
Abstract
Ser/Arg-rich (SR) proteins are RNA-binding proteins known as constitutive and alternative splicing (AS) regulators that regulate multiple aspects of the gene expression program. Ser/Arg-rich splicing factor 3 (SRSF3) is the smallest member of the SR protein family, and its level is controlled by multiple factors and involves complex mechanisms in eukaryote cells, whereas the aberrant expression of SRSF3 is associated with many human diseases, including cancer. Here, we review state-of-the-art research on SRSF3 in terms of its function, expression, and misregulation in human cancers. We emphasize the negative consequences of the overexpression of the SRSF3 oncogene in cancers, the pathways underlying SRSF3-mediated transformation, and implications of potential anticancer drugs by downregulation of SRSF3 expression for cancer therapy. Cumulative research on SRSF3 provides critical insight into its essential part in maintaining cellular processes, offering potential new targets for anti-cancer therapy.
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Affiliation(s)
- Zhixia Zhou
- Institute for Translational Medicine, The Affiliated Hospital of Qingdao University, College of Medicine, Qingdao University, Qingdao, China
| | - Qi Gong
- Departments of Pediatrics, Second Clinical Medical College of Qingdao University, Qingdao, China
| | - Zhijuan Lin
- Key Laboratory for Immunology in Universities of Shandong Province, School of Clinical Medicine, Weifang Medical University, Weifang, China
| | - Yin Wang
- Institute for Translational Medicine, The Affiliated Hospital of Qingdao University, College of Medicine, Qingdao University, Qingdao, China
| | - Mengkun Li
- Institute for Translational Medicine, The Affiliated Hospital of Qingdao University, College of Medicine, Qingdao University, Qingdao, China
| | - Lu Wang
- Institute for Translational Medicine, The Affiliated Hospital of Qingdao University, College of Medicine, Qingdao University, Qingdao, China
| | - Hongfei Ding
- Institute for Translational Medicine, The Affiliated Hospital of Qingdao University, College of Medicine, Qingdao University, Qingdao, China
| | - Peifeng Li
- Institute for Translational Medicine, The Affiliated Hospital of Qingdao University, College of Medicine, Qingdao University, Qingdao, China
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11
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Vo TV, Dhakshnamoorthy J, Larkin M, Zofall M, Thillainadesan G, Balachandran V, Holla S, Wheeler D, Grewal SIS. CPF Recruitment to Non-canonical Transcription Termination Sites Triggers Heterochromatin Assembly and Gene Silencing. Cell Rep 2020; 28:267-281.e5. [PMID: 31269446 DOI: 10.1016/j.celrep.2019.05.107] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2019] [Revised: 04/16/2019] [Accepted: 05/29/2019] [Indexed: 01/01/2023] Open
Abstract
In eukaryotic genomes, heterochromatin is targeted by RNAi machinery and/or by pathways requiring RNA elimination and transcription termination factors. However, a direct connection between termination machinery and RNA polymerase II (RNAPII) transcriptional activity at heterochromatic loci has remained elusive. Here, we show that, in fission yeast, the conserved cleavage and polyadenylation factor (CPF) is a key component involved in RNAi-independent assembly of constitutive and facultative heterochromatin domains and that CPF is broadly required to silence genes regulated by Clr4SUV39H. Remarkably, CPF is recruited to non-canonical termination sites within the body of genes by the YTH family RNA-binding protein Mmi1 and is required for RNAPII transcription termination and facultative heterochromatin assembly. CPF loading by Mmi1 also promotes the selective termination of long non-coding RNAs that regulate gene expression in cis. These analyses delineate a mechanism in which CPF loaded onto non-canonical termination sites specifies targets of heterochromatin assembly and gene silencing.
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Affiliation(s)
- Tommy V Vo
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, NIH, Bethesda, MD 20892, USA
| | - Jothy Dhakshnamoorthy
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, NIH, Bethesda, MD 20892, USA
| | - Madeline Larkin
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, NIH, Bethesda, MD 20892, USA
| | - Martin Zofall
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, NIH, Bethesda, MD 20892, USA
| | - Gobi Thillainadesan
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, NIH, Bethesda, MD 20892, USA
| | - Vanivilasini Balachandran
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, NIH, Bethesda, MD 20892, USA
| | - Sahana Holla
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, NIH, Bethesda, MD 20892, USA
| | - David Wheeler
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, NIH, Bethesda, MD 20892, USA
| | - Shiv I S Grewal
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, NIH, Bethesda, MD 20892, USA.
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12
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LaBella ML, Hujber EJ, Moore KA, Rawson RL, Merrill SA, Allaire PD, Ailion M, Hollien J, Bastiani MJ, Jorgensen EM. Casein Kinase 1δ Stabilizes Mature Axons by Inhibiting Transcription Termination of Ankyrin. Dev Cell 2020; 52:88-103.e18. [PMID: 31910362 DOI: 10.1016/j.devcel.2019.12.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Revised: 10/09/2019] [Accepted: 12/10/2019] [Indexed: 01/19/2023]
Abstract
After axon outgrowth and synapse formation, the nervous system transitions to a stable architecture. In C. elegans, this transition is marked by the appearance of casein kinase 1δ (CK1δ) in the nucleus. In CK1δ mutants, neurons continue to sprout growth cones into adulthood, leading to a highly ramified nervous system. Nervous system architecture in these mutants is completely restored by suppressor mutations in ten genes involved in transcription termination. CK1δ prevents termination by phosphorylating and inhibiting SSUP-72. SSUP-72 would normally remodel the C-terminal domain of RNA polymerase in anticipation of termination. The antitermination activity of CK1δ establishes the mature state of a neuron by promoting the expression of the long isoform of a single gene, the cytoskeleton protein Ankyrin.
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Affiliation(s)
- Matthew L LaBella
- Department of Biology, Howard Hughes Medical Institute, University of Utah, Salt Lake City, UT, USA
| | - Edward J Hujber
- Department of Biology, Howard Hughes Medical Institute, University of Utah, Salt Lake City, UT, USA
| | - Kristin A Moore
- Department of Biology, University of Utah, Salt Lake City, UT, USA
| | - Randi L Rawson
- Department of Biology, Howard Hughes Medical Institute, University of Utah, Salt Lake City, UT, USA
| | - Sean A Merrill
- Department of Biology, Howard Hughes Medical Institute, University of Utah, Salt Lake City, UT, USA
| | - Patrick D Allaire
- Department of Biology, Howard Hughes Medical Institute, University of Utah, Salt Lake City, UT, USA
| | - Michael Ailion
- Department of Biochemistry, University of Washington, Seattle, WA, USA
| | - Julie Hollien
- Department of Biology, University of Utah, Salt Lake City, UT, USA
| | | | - Erik M Jorgensen
- Department of Biology, Howard Hughes Medical Institute, University of Utah, Salt Lake City, UT, USA.
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13
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More DA, Kumar A. SRSF3: Newly discovered functions and roles in human health and diseases. Eur J Cell Biol 2020; 99:151099. [PMID: 32800280 DOI: 10.1016/j.ejcb.2020.151099] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Revised: 06/15/2020] [Accepted: 06/29/2020] [Indexed: 12/21/2022] Open
Abstract
The serine/arginine rich proteins (SR proteins) are members of a family of RNA binding proteins involved in regulating various features of RNA metabolism, including pre-mRNA constitutive and alternative splicing. In humans, a total of 12 SR splicing factors (SRSFs) namely SRSF1-SRSF12 have been reported. SRSF3, the smallest member of the SR family and the focus of this review, regulates critical steps in mRNA metabolism and has been shown to have mRNA-independent functions as well. Recent studies on SRSF3 have uncovered its role in a wide array of complex biological processes. We have also reviewed the involvement of SRSF3 in disease conditions like cancer, ageing, neurological and cardiac disorders. Finally, we have discussed in detail the autoregulation of SRSF3 and its implications in cancer and commented on the potential of SRSF3 as a therapeutic target, especially in the context of cancer.
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Affiliation(s)
- Dhanashree Anil More
- Department of Molecular Reproduction, Development and Genetics, Indian Institute of Science, Bangalore, 560012, India
| | - Arun Kumar
- Department of Molecular Reproduction, Development and Genetics, Indian Institute of Science, Bangalore, 560012, India.
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14
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Arribere JA, Kuroyanagi H, Hundley HA. mRNA Editing, Processing and Quality Control in Caenorhabditis elegans. Genetics 2020; 215:531-568. [PMID: 32632025 PMCID: PMC7337075 DOI: 10.1534/genetics.119.301807] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Accepted: 05/03/2020] [Indexed: 02/06/2023] Open
Abstract
While DNA serves as the blueprint of life, the distinct functions of each cell are determined by the dynamic expression of genes from the static genome. The amount and specific sequences of RNAs expressed in a given cell involves a number of regulated processes including RNA synthesis (transcription), processing, splicing, modification, polyadenylation, stability, translation, and degradation. As errors during mRNA production can create gene products that are deleterious to the organism, quality control mechanisms exist to survey and remove errors in mRNA expression and processing. Here, we will provide an overview of mRNA processing and quality control mechanisms that occur in Caenorhabditis elegans, with a focus on those that occur on protein-coding genes after transcription initiation. In addition, we will describe the genetic and technical approaches that have allowed studies in C. elegans to reveal important mechanistic insight into these processes.
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Affiliation(s)
| | - Hidehito Kuroyanagi
- Laboratory of Gene Expression, Medical Research Institute, Tokyo Medical and Dental University, Tokyo 113-8510, Japan, and
| | - Heather A Hundley
- Medical Sciences Program, Indiana University School of Medicine-Bloomington, Indiana 47405
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15
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Guo J, Wang X, Jia J, Jia R. Underexpression of SRSF3 and its target gene RBMX predicts good prognosis in patients with head and neck cancer. J Oral Sci 2020; 62:175-179. [PMID: 32132325 DOI: 10.2334/josnusd.18-0485] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022]
Abstract
Head and neck cancer collectively is one of the most common cancer types in the world. Oral squamous cell carcinoma (OSCC) is the most common subtype of head and neck cancer. SRSF3 is a proto-oncogene and is overexpressed in patients with OSCC. However, the relationship between SRSF3 expression and the clinical outcomes of patients with head and neck cancer remains unclear. By using the cBioPortal for Cancer Genomics, a public online tool originally developed at Memorial Sloan Kettering Cancer Center (New York, NY, USA), it was revealed that patients with head and neck cancer with an underexpression of SRSF3 showed better overall and disease-/progression-free survival rates. Moreover, 227 genes were found to be significantly coexpressed with SRSF3 in head and neck cancer. Then, in combination with the analysis of a previous splice-array dataset that included significantly changed genes after the silencing of SRSF3, four potential target genes of SRSF3 were identified. RBMX and HNRNPL were further confirmed to be target genes of SRSF3. Moreover, the underexpression of RBMX was determined to be significantly associated with a favorable overall survival rate among patients, while patients with an underexpression of both SRSF3 and RBMX is a subgroup of individuals with better prognoses than all other patients. These results suggest that the underexpression of SRSF3 and that of its target RBMX can be used as potential biomarkers to predict favorable overall survival among head and neck cancer patients.
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Affiliation(s)
- Jihua Guo
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory of Oral Biomedicine Ministry of Education, School & Hospital of Stomatology, Wuhan University.,Department of Endodontics, School & Hospital of Stomatology, Wuhan University
| | - Xiaole Wang
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory of Oral Biomedicine Ministry of Education, School & Hospital of Stomatology, Wuhan University
| | - Jun Jia
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory of Oral Biomedicine Ministry of Education, School & Hospital of Stomatology, Wuhan University.,Department of Oral and Maxillofacial Surgery, School & Hospital of Stomatology, Wuhan University
| | - Rong Jia
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory of Oral Biomedicine Ministry of Education, School & Hospital of Stomatology, Wuhan University
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16
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Pathway-guided analysis identifies Myc-dependent alternative pre-mRNA splicing in aggressive prostate cancers. Proc Natl Acad Sci U S A 2020; 117:5269-5279. [PMID: 32086391 PMCID: PMC7071906 DOI: 10.1073/pnas.1915975117] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
We sought to define the landscape of alternative pre-mRNA splicing in prostate cancers and the relationship of exon choice to known cancer driver alterations. To do so, we compiled a metadataset composed of 876 RNA-sequencing (RNA-Seq) samples from five publicly available sources representing a range of prostate phenotypes from normal tissue to drug-resistant metastases. We subjected these samples to exon-level analysis with rMATS-turbo, purpose-built software designed for large-scale analyses of splicing, and identified 13,149 high-confidence cassette exon events with variable incorporation across samples. We then developed a computational framework, pathway enrichment-guided activity study of alternative splicing (PEGASAS), to correlate transcriptional signatures of 50 different cancer driver pathways with these alternative splicing events. We discovered that Myc signaling was correlated with incorporation of a set of 1,039 cassette exons enriched in genes encoding RNA binding proteins. Using a human prostate epithelial transformation assay, we confirmed the Myc regulation of 147 of these exons, many of which introduced frameshifts or encoded premature stop codons. Our results connect changes in alternative pre-mRNA splicing to oncogenic alterations common in prostate and many other cancers. We also establish a role for Myc in regulating RNA splicing by controlling the incorporation of nonsense-mediated decay-determinant exons in genes encoding RNA binding proteins.
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17
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Sun Y, Yan L, Guo J, Shao J, Jia R. Downregulation of SRSF3 by antisense oligonucleotides sensitizes oral squamous cell carcinoma and breast cancer cells to paclitaxel treatment. Cancer Chemother Pharmacol 2019; 84:1133-1143. [PMID: 31515668 DOI: 10.1007/s00280-019-03945-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2019] [Accepted: 08/28/2019] [Indexed: 12/30/2022]
Abstract
PURPOSE Paclitaxel (PTX) is widely used in the chemotherapy of many cancers, including breast cancer and oral squamous cell carcinoma (OSCC). However, many patients respond poorly to PTX treatment. The SRSF3 oncogene and several splicing factors play important roles in OSCC tumorigenesis. This study aimed to understand the function of splicing factors in PTX treatment and improve the therapeutic effects of PTX treatment. METHODS Splicing factors regulated by PTX treatment were screened in CAL 27 cell by reverse transcription polymerase chain reaction. The function of SRSF3 in PTX treatment was analyzed by gain-of-function or loss-of-function assay in OSCC cell lines CAL 27 and SCC-9 and breast cancer cell line MCF-7. Alternative splicing of SRSF3 exon 4 in cancer tissues or cells was analyzed by RT-PCR and online program TSVdb. SRSF3-specific antisense oligonucleotide (ASO) SR-3 was used to downregulate SRSF3 expression and enhance the effect of PTX treatment. RESULTS PTX treatment decreased SRSF3 expression, and SRSF3 overexpression rescued the growth inhibition caused by PTX in both OSCC and breast cancer cells. Moreover, we found that PTX treatment could repress SRSF3 exon 4 (containing an in-frame stop codon) exclusion and then decrease the SRSF3 protein expression. Increased exclusion of SRSF3 exon 4 is correlated with poor survival in OSCC and breast cancer patients. SR-3 downregulated SRSF3 protein expression and significantly increased the sensitivity of cancer cells to PTX treatment. CONCLUSIONS SRSF3 downregulation by ASO sensitizes cancer cells to PTX treatment.
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Affiliation(s)
- Yanan Sun
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) and Key Laboratory of Oral Biomedicine Ministry of Education, School and Hospital of Stomatology, Wuhan University, 237 Luoyu Road, 430079, Wuhan, People's Republic of China
| | - Lingyan Yan
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) and Key Laboratory of Oral Biomedicine Ministry of Education, School and Hospital of Stomatology, Wuhan University, 237 Luoyu Road, 430079, Wuhan, People's Republic of China
| | - Jihua Guo
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) and Key Laboratory of Oral Biomedicine Ministry of Education, School and Hospital of Stomatology, Wuhan University, 237 Luoyu Road, 430079, Wuhan, People's Republic of China.
| | - Jun Shao
- Hubei Cancer Hospital, 116 Zhuodaoquan South Load, 430079, Wuhan, People's Republic of China.
| | - Rong Jia
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) and Key Laboratory of Oral Biomedicine Ministry of Education, School and Hospital of Stomatology, Wuhan University, 237 Luoyu Road, 430079, Wuhan, People's Republic of China.
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18
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Genetic variations within alternative splicing associated genes are associated with breast cancer susceptibility in Chinese women. Gene 2019; 706:140-145. [DOI: 10.1016/j.gene.2019.05.022] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Revised: 05/06/2019] [Accepted: 05/08/2019] [Indexed: 11/20/2022]
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19
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Jia R, Ajiro M, Yu L, McCoy P, Zheng ZM. Oncogenic splicing factor SRSF3 regulates ILF3 alternative splicing to promote cancer cell proliferation and transformation. RNA (NEW YORK, N.Y.) 2019; 25:630-644. [PMID: 30796096 PMCID: PMC6467003 DOI: 10.1261/rna.068619.118] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2018] [Accepted: 02/21/2019] [Indexed: 05/28/2023]
Abstract
Alternative RNA splicing is an important focus in molecular and clinical oncology. We report here that SRSF3 regulates alternative RNA splicing of interleukin enhancer binding factor 3 (ILF3) and production of this double-strand RNA-binding protein. An increased coexpression of ILF3 isoforms and SRSF3 was found in various types of cancers. ILF3 isoform-1 and isoform-2 promote cell proliferation and transformation. Tumor cells with reduced SRSF3 expression produce aberrant isoform-5 and -7 of ILF3. By binding to RNA sequence motifs, SRSF3 regulates the production of various ILF3 isoforms by exclusion/inclusion of ILF3 exon 18 or by selection of an alternative 3' splice site within exon 18. ILF3 isoform-5 and isoform-7 suppress tumor cell proliferation and the isoform-7 induces cell apoptosis. Our data indicate that ILF3 isoform-1 and isoform-2 are two critical factors for cell proliferation and transformation. The increased SRSF3 expression in cancer cells plays an important role in maintaining the steady status of ILF3 isoform-1 and isoform-2.
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Affiliation(s)
- Rong Jia
- Tumor Virus RNA Biology Section, RNA Biology Laboratory, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, Maryland 21702, USA
- State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) and Ke Laboratory for Oral Biomedicine of Ministry of Education (KLOBM), School and Hospital of Stomatology, Wuhan University, Wuhan, Hubei 430079, China
| | - Masahiko Ajiro
- Tumor Virus RNA Biology Section, RNA Biology Laboratory, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, Maryland 21702, USA
| | - Lulu Yu
- Tumor Virus RNA Biology Section, RNA Biology Laboratory, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, Maryland 21702, USA
| | - Philip McCoy
- Flow Cytometry Core Facility, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Zhi-Ming Zheng
- Tumor Virus RNA Biology Section, RNA Biology Laboratory, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, Maryland 21702, USA
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Reines D. A fluorescent assay for the genetic dissection of the RNA polymerase II termination machinery. Methods 2019; 159-160:124-128. [PMID: 30616008 DOI: 10.1016/j.ymeth.2018.12.011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Revised: 12/27/2018] [Accepted: 12/28/2018] [Indexed: 01/25/2023] Open
Abstract
RNA polymerase II is a highly processive enzyme that synthesizes mRNAs and some non-protein coding RNAs. Termination of transcription, which entails release of the transcript and disengagement of the polymerase, requires an active process. In yeast, there are at least two multi-protein complexes needed for termination of transcription, depending upon which class of RNAs are being acted upon. In general, the two classes are relatively short non-coding RNAs (e.g. snoRNAs) and relatively long mRNAs, although there are exceptions. Here, a procedure is described in which defective termination can be detected in living cells, resulting in a method that allows strains with mutations in termination factors or cis-acting sequences, to be identified and recovered. The strategy employs a reporter plasmid with a galactose inducible promoter driving transcription of green fluorescent protein which yields highly fluorescent cells. When a test terminator is inserted between the promoter and the fluorescent protein reading frame, cells fail to fluoresce. Mutant strains that have lost termination capability, so called terminator-override mutants, gain expression of the fluorescent protein and can be collected by fluorescence activated cell sorting. The strategy is robust since acquisition of fluorescence is a positive trait that has a low probability of happening adventitiously. Live mutant cells can easily be cloned from the population of positive candidates. Flow sorting is a sensitive, high-throughput detection step capable of discovering spontaneous mutations in yeast with high fidelity.
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Affiliation(s)
- Daniel Reines
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322, United States.
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21
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Zhou L, Guo J, Jia R. Oncogene SRSF3 suppresses autophagy via inhibiting BECN1 expression. Biochem Biophys Res Commun 2019; 509:966-972. [PMID: 30654935 DOI: 10.1016/j.bbrc.2019.01.048] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Accepted: 01/08/2019] [Indexed: 12/31/2022]
Abstract
Autophagy is an evolutionarily conserved cellular catabolic process. Dysfunction in the autophagy pathway has been demonstrated to be associated with many human diseases, including cancer. Alternative splicing of pre-mRNA is also an evolutionarily conserved regulatory mechanism of gene expression. Dysregulation of alternative splicing is increasingly linked to cancer. However, the association between these two cellular conserved processes is unclear. Splicing factors are critical players in the regulation of alternative splicing of pre-mRNA. We analyzed the expression of 28 splicing factors during hypoxia-induced autophagy in three oral squamous cell carcinoma (OSCC) cell lines. We discovered that oncogenes SRSF3 and SRSF1 are significantly downregulated in all three cell lines. Moreover, knockdown of SRSF3 increased autophagic activity, whereas overexpression of SRSF3 inhibited hypoxia-induced autophagy. Loss-of-function and gain-of-function assays also showed that SRSF3 inhibits the expression of p65 and FoxO1 and their downstream target gene BECN1, a key regulator of autophagy. Our results demonstrated that splicing factor SRSF3 is an autophagy suppressor.
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Affiliation(s)
- Lu Zhou
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory of Oral Biomedicine Ministry of Education, School & Hospital of Stomatology, Wuhan University, Wuhan, PR China.
| | - Jihua Guo
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory of Oral Biomedicine Ministry of Education, School & Hospital of Stomatology, Wuhan University, Wuhan, PR China; Department of Endodontics, School & Hospital of Stomatology, Wuhan University, Wuhan, PR China.
| | - Rong Jia
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory of Oral Biomedicine Ministry of Education, School & Hospital of Stomatology, Wuhan University, Wuhan, PR China.
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Urbanski L, Leclair N, Anczuków O. Alternative-splicing defects in cancer: Splicing regulators and their downstream targets, guiding the way to novel cancer therapeutics. WILEY INTERDISCIPLINARY REVIEWS. RNA 2018; 9:e1476. [PMID: 29693319 PMCID: PMC6002934 DOI: 10.1002/wrna.1476] [Citation(s) in RCA: 248] [Impact Index Per Article: 35.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Revised: 02/27/2018] [Accepted: 03/01/2018] [Indexed: 12/14/2022]
Abstract
Defects in alternative splicing are frequently found in human tumors and result either from mutations in splicing-regulatory elements of specific cancer genes or from changes in the regulatory splicing machinery. RNA splicing regulators have emerged as a new class of oncoproteins and tumor suppressors, and contribute to disease progression by modulating RNA isoforms involved in the hallmark cancer pathways. Thus, dysregulation of alternative RNA splicing is fundamental to cancer and provides a potentially rich source of novel therapeutic targets. Here, we review the alterations in splicing regulatory factors detected in human tumors, as well as the resulting alternatively spliced isoforms that impact cancer hallmarks, and discuss how they contribute to disease pathogenesis. RNA splicing is a highly regulated process and, as such, the regulators are themselves tightly regulated. Differential transcriptional and posttranscriptional regulation of splicing factors modulates their levels and activities in tumor cells. Furthermore, the composition of the tumor microenvironment can also influence which isoforms are expressed in a given cell type and impact drug responses. Finally, we summarize current efforts in targeting alternative splicing, including global splicing inhibition using small molecules blocking the spliceosome or splicing-factor-modifying enzymes, as well as splice-switching RNA-based therapeutics to modulate cancer-specific splicing isoforms. This article is categorized under: RNA in Disease and Development > RNA in Disease RNA Processing > Splicing Regulation/Alternative Splicing.
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Systematic Functional Characterization of Human 21st Chromosome Orthologs in Caenorhabditis elegans. G3-GENES GENOMES GENETICS 2018; 8:967-979. [PMID: 29367452 PMCID: PMC5844316 DOI: 10.1534/g3.118.200019] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Individuals with Down syndrome have neurological and muscle impairments due to an additional copy of the human 21st chromosome (HSA21). Only a few of ∼200 HSA21 genes encoding proteins have been linked to specific Down syndrome phenotypes, while the remainder are understudied. To identify poorly characterized HSA21 genes required for nervous system function, we studied behavioral phenotypes caused by loss-of-function mutations in conserved HSA21 orthologs in the nematode Caenorhabditis elegans. We identified 10 HSA21 orthologs that are required for neuromuscular behaviors: cle-1 (COL18A1), cysl-2 (CBS), dnsn-1 (DONSON), eva-1 (EVA1C), mtq-2 (N6ATM1), ncam-1 (NCAM2), pad-2 (POFUT2), pdxk-1 (PDXK), rnt-1 (RUNX1), and unc-26 (SYNJ1). We also found that three of these genes are required for normal release of the neurotransmitter acetylcholine. This includes a known synaptic gene unc-26 (SYNJ1), as well as uncharacterized genes pdxk-1 (PDXK) and mtq-2 (N6ATM1). As the first systematic functional analysis of HSA21 orthologs, this study may serve as a platform to understand genes that underlie phenotypes associated with Down syndrome.
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MicroRNA-1908-5p contributes to the oncogenic function of the splicing factor SRSF3. Oncotarget 2018; 8:8342-8355. [PMID: 28039456 PMCID: PMC5352405 DOI: 10.18632/oncotarget.14184] [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: 08/24/2016] [Accepted: 11/22/2016] [Indexed: 01/21/2023] Open
Abstract
Serine/arginine (SR)-rich proteins that contain RS domains and SR repeats have diverse cellular functions including transcription, polyadenylation, translation, and RNA export. The splicing factor SRSF3, also termed SRp20, is the smallest member of the SR protein family and is a known proto-oncogene. Although it is implicated in the malignant phenotypes of various cancer cells, the molecular mechanism underlying SRSF3-mediated cancer progression is still obscure. We investigated here the oncogenic functions of SRSF3 in osteosarcoma U2OS cells. Knockdown of SRSF3 inhibited proliferation, clonogenicity, and metastatic potential including migration and invasion. It also decreased the level of miR-1908 independent of its host gene FADS1. Although FADS1 was not associated with SRSF3-mediated malignant properties, overexpression of miR-1908-5p increased cell proliferation, migration, and invasion, suggesting that miR-1908-5p is responsible for the oncogenic functions of SRSF3. Knockdown of SRSF3 decreased the expression of miR-1908-5p by inhibiting transactivation of NF-κB. We observed that miR-1908-5p downregulated NF-κB inhibitor interacting Ras-like 2 (NKIRAS2), a negative regulator of the NF-κB pathway by directly binding to the 3'UTR of NKIRAS2 mRNA. Consistent with overexpression of miR-1908-5p, knockdown of NKIRAS2 diminished the expression level of IκB-β and provoked translocation of NF-κB into the nucleus where it transcriptionally activates its target genes including miR-1908-5p expression, thus elevating the proliferation and metastatic potential. Taken together, our results demonstrate that SRSF3 confers the malignant characteristics on cancer cells via the SRSF3/miR-1908-5p/NKIRAS2 axis.
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Chen F, Chisholm AD, Jin Y. Tissue-specific regulation of alternative polyadenylation represses expression of a neuronal ankyrin isoform in C. elegans epidermal development. Development 2017; 144:698-707. [PMID: 28087624 DOI: 10.1242/dev.146001] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2016] [Accepted: 01/02/2017] [Indexed: 12/26/2022]
Abstract
Differential mRNA polyadenylation plays an important role in shaping the neuronal transcriptome. In C. elegans, several ankyrin isoforms are produced from the unc-44 locus through alternative polyadenylation. Here, we identify a key role for an intronic polyadenylation site (PAS) in temporal- and tissue-specific regulation of UNC-44/ankyrin isoforms. Removing an intronic PAS results in ectopic expression of the neuronal ankyrin isoform in non-neural tissues. This mis-expression underlies epidermal developmental defects in mutants of the conserved tumor suppressor death-associated protein kinase dapk-1 We have previously reported that the use of this intronic PAS depends on the nuclear polyadenylation factor SYDN-1, which inhibits the RNA polymerase II CTD phosphatase SSUP-72. Consistent with this, loss of sydn-1 blocks ectopic expression of neuronal ankyrin and suppresses epidermal morphology defects of dapk-1 These effects of sydn-1 are mediated by ssup-72 autonomously in the epidermis. We also show that a peptidyl-prolyl isomerase PINN-1 antagonizes SYDN-1 in the spatiotemporal control of neuronal ankyrin isoform. Moreover, the nuclear localization of PINN-1 is altered in dapk-1 mutants. Our data reveal that tissue and stage-specific expression of ankyrin isoforms relies on differential activity of positive and negative regulators of alternative polyadenylation.
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Affiliation(s)
- Fei Chen
- Neurobiology Section, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA.,Howard Hughes Medical Institute, Department of Cellular and Molecular Medicine, School of Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Andrew D Chisholm
- Neurobiology Section, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA
| | - Yishi Jin
- Neurobiology Section, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA .,Howard Hughes Medical Institute, Department of Cellular and Molecular Medicine, School of Medicine, University of California, San Diego, La Jolla, CA 92093, USA
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Garrido-Lecca A, Saldi T, Blumenthal T. Localization of RNAPII and 3' end formation factor CstF subunits on C. elegans genes and operons. Transcription 2016; 7:96-110. [PMID: 27124504 DOI: 10.1080/21541264.2016.1168509] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Transcription termination is mechanistically coupled to pre-mRNA 3' end formation to prevent transcription much beyond the gene 3' end. C. elegans, however, engages in polycistronic transcription of operons in which 3' end formation between genes is not accompanied by termination. We have performed RNA polymerase II (RNAPII) and CstF ChIP-seq experiments to investigate at a genome-wide level how RNAPII can transcribe through multiple poly-A signals without causing termination. Our data shows that transcription proceeds in some ways as if operons were composed of multiple adjacent single genes. Total RNAPII shows a small peak at the promoter of the gene cluster and a much larger peak at 3' ends. These 3' peaks coincide with maximal phosphorylation of Ser2 within the C-terminal domain (CTD) of RNAPII and maximal localization of the 3' end formation factor CstF. This pattern occurs at all 3' ends including those at internal sites in operons where termination does not occur. Thus the normal mechanism of 3' end formation does not always result in transcription termination. Furthermore, reduction of CstF50 by RNAi did not substantially alter the pattern of CstF64, total RNAPII, or Ser2 phosphorylation at either internal or terminal 3' ends. However, CstF50 RNAi did result in a subtle reduction of CstF64 binding upstream of the site of 3' cleavage, suggesting that the CstF50/CTD interaction may facilitate bringing the 3' end machinery to the transcription complex.
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Affiliation(s)
- Alfonso Garrido-Lecca
- a Department of Molecular, Cellular, and Developmental Biology , University of Colorado , Boulder , CO , USA
| | - Tassa Saldi
- a Department of Molecular, Cellular, and Developmental Biology , University of Colorado , Boulder , CO , USA
| | - Thomas Blumenthal
- a Department of Molecular, Cellular, and Developmental Biology , University of Colorado , Boulder , CO , USA
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27
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Chen F, Zhou Y, Qi YB, Khivansara V, Li H, Chun SY, Kim JK, Fu XD, Jin Y. Context-dependent modulation of Pol II CTD phosphatase SSUP-72 regulates alternative polyadenylation in neuronal development. Genes Dev 2016; 29:2377-90. [PMID: 26588990 PMCID: PMC4691892 DOI: 10.1101/gad.266650.115] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Chen et al. find that loss of function in ssup-72, a Ser5 phosphatase for the RNA polymerase II C-terminal domain (CTD), dampens transcription termination at a strong intronic poly(A) site (PAS) in unc-44/ankyrin yet promotes termination at the weak intronic PAS of the MAP kinase dlk-1. This work reveals a mechanism by which regulation of CTD phosphorylation controls coding region alternative polyadenylation in the nervous system. Alternative polyadenylation (APA) is widespread in neuronal development and activity-mediated neural plasticity. However, the underlying molecular mechanisms are largely unknown. We used systematic genetic studies and genome-wide surveys of the transcriptional landscape to identify a context-dependent regulatory pathway controlling APA in the Caenorhabditis elegans nervous system. Loss of function in ssup-72, a Ser5 phosphatase for the RNA polymerase II (Pol II) C-terminal domain (CTD), dampens transcription termination at a strong intronic polyadenylation site (PAS) in unc-44/ankyrin yet promotes termination at the weak intronic PAS of the MAP kinase dlk-1. A nuclear protein, SYDN-1, which regulates neuronal development, antagonizes the function of SSUP-72 and several nuclear polyadenylation factors. This regulatory pathway allows the production of a neuron-specific isoform of unc-44 and an inhibitory isoform of dlk-1. Dysregulation of the unc-44 and dlk-1 mRNA isoforms in sydn-1 mutants impairs neuronal development. Deleting the intronic PAS of unc-44 results in increased pre-mRNA processing of neuronal ankyrin and suppresses sydn-1 mutants. These results reveal a mechanism by which regulation of CTD phosphorylation controls coding region APA in the nervous system.
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Affiliation(s)
- Fei Chen
- Neurobiology Section, Division of Biological Sciences, University of California at San Diego, La Jolla, California 92093, USA; Howard Hughes Medical Institute, University of California at San Diego, La Jolla, California 92093, USA
| | - Yu Zhou
- Department of Cellular and Molecular Medicine, School of Medicine, University of California at San Diego, La Jolla, California 92093, USA
| | - Yingchuan B Qi
- Neurobiology Section, Division of Biological Sciences, University of California at San Diego, La Jolla, California 92093, USA
| | - Vishal Khivansara
- Life Sciences Institute, Department of Human Genetics, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Hairi Li
- Department of Cellular and Molecular Medicine, School of Medicine, University of California at San Diego, La Jolla, California 92093, USA
| | - Sang Young Chun
- Department of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - John K Kim
- Life Sciences Institute, Department of Human Genetics, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Xiang-Dong Fu
- Department of Cellular and Molecular Medicine, School of Medicine, University of California at San Diego, La Jolla, California 92093, USA
| | - Yishi Jin
- Neurobiology Section, Division of Biological Sciences, University of California at San Diego, La Jolla, California 92093, USA; Howard Hughes Medical Institute, University of California at San Diego, La Jolla, California 92093, USA; Department of Cellular and Molecular Medicine, School of Medicine, University of California at San Diego, La Jolla, California 92093, USA
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Computational exploration of microRNAs from expressed sequence tags of Humulus lupulus , target predictions and expression analysis. Comput Biol Chem 2015; 59 Pt A:131-41. [DOI: 10.1016/j.compbiolchem.2015.09.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2015] [Revised: 09/02/2015] [Accepted: 09/07/2015] [Indexed: 11/19/2022]
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PTBP1 and PTBP2 impaired autoregulation of SRSF3 in cancer cells. Sci Rep 2015; 5:14548. [PMID: 26416554 PMCID: PMC4586487 DOI: 10.1038/srep14548] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2015] [Accepted: 07/21/2015] [Indexed: 12/20/2022] Open
Abstract
Splicing factors are key players in the regulation of alternative splicing of pre-mRNAs. Overexpression of splicing factors, including SRSF3, has been strongly linked with oncogenesis. However, the mechanisms behind their overexpression remain largely unclear. Autoregulation is a common mechanism to maintain relative stable expression levels of splicing factors in cells. SRSF3 regulates its own expression by enhancing the inclusion of an alternative exon 4 with an in-frame stop codon. We found that the inclusion of SRSF3 exon 4 is impaired in oral squamous cell carcinoma (OSCC) cells. PTBP1 and PTBP2 bind to an exonic splicing suppressor in exon 4 and inhibit its inclusion, which results in overexpression of full length functional SRSF3. Overexpression of SRSF3, in turn, promotes PTBP2 expression. Our results suggest a novel mechanism for the overexpression of oncogenic splicing factor via impairing autoregulation in cancer cells.
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Metabolome and proteome changes with aging in Caenorhabditis elegans. Exp Gerontol 2015; 72:67-84. [PMID: 26390854 DOI: 10.1016/j.exger.2015.09.013] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2015] [Revised: 09/15/2015] [Accepted: 09/16/2015] [Indexed: 01/13/2023]
Abstract
To expand the understanding of aging in the model organism Caenorhabditis elegans, global quantification of metabolite and protein levels in young and aged nematodes was performed using mass spectrometry. With age, there was a decreased abundance of proteins functioning in transcription termination, mRNA degradation, mRNA stability, protein synthesis, and proteasomal function. Furthermore, there was altered S-adenosyl methionine metabolism as well as a decreased abundance of the S-adenosyl methionine synthetase (SAMS-1) protein. Other aging-related changes included alterations in free fatty acid levels and composition, decreased levels of ribosomal proteins, decreased levels of NADP-dependent isocitrate dehydrogenase (IDH1), a shift in the cellular redox state, an increase in sorbitol content, alterations in free amino acid levels, and indications of altered muscle function and sarcoplasmic reticulum Ca(2+) homeostasis. There were also decreases in pyrimidine and purine metabolite levels, most markedly nitrogenous bases. Supplementing the culture medium with cytidine (a pyrimidine nucleoside) or hypoxanthine (a purine base) increased lifespan slightly, suggesting that aging-induced alterations in ribonucleotide metabolism affect lifespan. An age-related increase in body size, lipotoxicity from ectopic yolk lipoprotein accumulation, a decline in NAD(+) levels, and mitochondrial electron transport chain dysfunction may explain many of these changes. In addition, dietary restriction in aged worms resulting from sarcopenia of the pharyngeal pump likely decreases the abundance of SAMS-1, possibly leading to decreased phosphatidylcholine levels, larger lipid droplets, and ER and mitochondrial stress. The complementary use of proteomics and metabolomics yielded unique insights into the molecular processes altered with age in C. elegans.
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31
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He X, Zhang P. Serine/arginine-rich splicing factor 3 (SRSF3) regulates homologous recombination-mediated DNA repair. Mol Cancer 2015; 14:158. [PMID: 26282282 PMCID: PMC4539922 DOI: 10.1186/s12943-015-0422-1] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Accepted: 07/28/2015] [Indexed: 12/20/2022] Open
Abstract
Background Our previous work found that serine/arginine-rich splicing factor 3 (SRSF3) was overexpressed in human ovarian cancer and the overexpression of SRSF3 was required for ovarian cancer cell growth and survival. The mechanism underlying the role of SRSF3 in ovarian cancer remains to be addressed. Methods We conducted microarray analysis to profile the gene expression and splicing in SRSF3-knockdown cells and employed quantitative PCR and western blotting to validate the profiling results. We used chromatin immunoprecipitation to study transcription and the direct repeat green fluorescent protein reporter assay to study homologous recombination-mediated DNA repair (HRR). Results We identified 687 genes with altered expression and 807 genes with altered splicing in SRSF3-knockdown cells. Among expression-altered genes, those involved in HRR, including BRCA1, BRIP1 and RAD51, were enriched and were all downregulated. We demonstrated that the downregulation of BRCA1, BRIP1 and RAD51 expression was caused by decreased transcription and not due to increased nonsense-mediated mRNA decay. Further, we found that SRSF3 knockdown impaired HRR activity in the cell and increased the level of γ-H2AX, a biomarker for double-strand DNA breaks. Finally, we observed that SRSF3 knockdown changed splicing pattern of KMT2C, a H3K4-specific histone methyltransferase, and reduced the levels of mono- and trimethylated H3K4. Conclusion These results suggest that SRSF3 is a new regulator of HRR process, which possibly regulates the expression of HRR-related genes indirectly through an epigenetic pathway. This new function of SRSF3 not only explains why overexpression of SRSF3 is required for ovarian cancer cell growth and survival but also offers a new insight into the mechanism of the neoplastic transformation. Electronic supplementary material The online version of this article (doi:10.1186/s12943-015-0422-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Xiaolong He
- Department of Biopharmaceutical Sciences, College of Pharmacy, University of Illinois at Chicago-Rockford Campus, 1601 Parkview Avenue, Room N308, Rockford, IL, 61107, USA. .,University of Illinois Cancer Center, University of Illinois at Chicago, Chicago, IL, USA.
| | - Pei Zhang
- Department of Biopharmaceutical Sciences, College of Pharmacy, University of Illinois at Chicago-Rockford Campus, 1601 Parkview Avenue, Room N308, Rockford, IL, 61107, USA.
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Homer1 alternative splicing is regulated by gonadotropin-releasing hormone and modulates gonadotropin gene expression. Mol Cell Biol 2014; 34:1747-56. [PMID: 24591653 DOI: 10.1128/mcb.01401-13] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Hypothalamic gonadotropin-releasing hormone (GnRH) plays a critical role in reproductive physiology by regulating follicle-stimulating hormone (FSH) and luteinizing hormone (LH) gene expression in the pituitary. Analysis of gonadotrope deep-sequencing data identified a global regulation of pre-mRNA splicing by GnRH. Homer1, a gene encoding a postsynaptic density scaffolding protein, was selected for further study. Homer1 expresses a short splice form, Homer1a, and more-abundant long transcripts Homer1b/c. GnRH induced a modest increase in Homer1b/c expression and a dramatic increase in the Homer1a splice form. G protein knockdown studies suggested that the Homer1 induction, but not the regulated splicing, was Gαq/11 dependent. Phosphorylation of the splicing regulator SRp20 was found to be induced by GnRH. SRp20 depletion attenuated the GnRH-induced increase in the Homer1a-to-Homer1b/c ratio and modulated the effects of GnRH on FSHβ and LHβ expression. Homer1 gene knockdown resulted in increased GnRH-induced FSHβ and LHβ transcript levels. Furthermore, splice-form-specific reduction of Homer1b/c increased both FSHβ and LHβ mRNA induction, whereas reduction of Homer1a had the opposite effect on FSHβ induction. These results indicate that the regulation of Homer1 splicing by GnRH contributes to gonadotropin gene control.
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Duc C, Sherstnev A, Cole C, Barton GJ, Simpson GG. Transcription termination and chimeric RNA formation controlled by Arabidopsis thaliana FPA. PLoS Genet 2013; 9:e1003867. [PMID: 24204292 PMCID: PMC3814327 DOI: 10.1371/journal.pgen.1003867] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2013] [Accepted: 08/22/2013] [Indexed: 11/18/2022] Open
Abstract
Alternative cleavage and polyadenylation influence the coding and regulatory potential of mRNAs and where transcription termination occurs. Although widespread, few regulators of this process are known. The Arabidopsis thaliana protein FPA is a rare example of a trans-acting regulator of poly(A) site choice. Analysing fpa mutants therefore provides an opportunity to reveal generic consequences of disrupting this process. We used direct RNA sequencing to quantify shifts in RNA 3′ formation in fpa mutants. Here we show that specific chimeric RNAs formed between the exons of otherwise separate genes are a striking consequence of loss of FPA function. We define intergenic read-through transcripts resulting from defective RNA 3′ end formation in fpa mutants and detail cryptic splicing and antisense transcription associated with these read-through RNAs. We identify alternative polyadenylation within introns that is sensitive to FPA and show FPA-dependent shifts in IBM1 poly(A) site selection that differ from those recently defined in mutants defective in intragenic heterochromatin and DNA methylation. Finally, we show that defective termination at specific loci in fpa mutants is shared with dicer-like 1 (dcl1) or dcl4 mutants, leading us to develop alternative explanations for some silencing roles of these proteins. We relate our findings to the impact that altered patterns of 3′ end formation can have on gene and genome organisation. The ends of almost all eukaryotic protein-coding genes are defined by a poly(A) signal. When genes are transcribed into mRNA by RNA polymerase II, the poly(A) signal guides cleavage of the precursor mRNA at a particular site; this is accompanied by the addition of a poly(A) tail to the mRNA and termination of transcription. Many genes have more than one poly(A) signal and the regulated choice of which to select can effectively determine what the gene will code for, how the gene can be regulated and where transcription termination occurs. We discovered a rare example of a regulator of poly(A) site choice, called FPA, while studying flower development in the model plant Arabidopsis thaliana. Studying FPA therefore provides an opportunity to understand not only its roles in plant biology but also the generic consequences of disrupting alternative polyadenylation. In this study, we use a technique called direct RNA sequencing to quantify genome-wide shifts in poly(A) site selection in plants that lack FPA function. One of our most striking findings is that in the absence of FPA we detect chimeric RNAs formed between two otherwise separate and well-characterised genes.
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Affiliation(s)
- Céline Duc
- College of Life Sciences, University of Dundee, Dundee, Scotland, United Kingdom
| | - Alexander Sherstnev
- College of Life Sciences, University of Dundee, Dundee, Scotland, United Kingdom
| | - Christian Cole
- College of Life Sciences, University of Dundee, Dundee, Scotland, United Kingdom
| | - Geoffrey J. Barton
- College of Life Sciences, University of Dundee, Dundee, Scotland, United Kingdom
- * E-mail: (GJB); (GGS)
| | - Gordon G. Simpson
- College of Life Sciences, University of Dundee, Dundee, Scotland, United Kingdom
- James Hutton Institute, Invergowrie, Dundee, Scotland, United Kingdom
- * E-mail: (GJB); (GGS)
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Corbo C, Orrù S, Salvatore F. SRp20: an overview of its role in human diseases. Biochem Biophys Res Commun 2013; 436:1-5. [PMID: 23685143 DOI: 10.1016/j.bbrc.2013.05.027] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2013] [Accepted: 05/07/2013] [Indexed: 10/26/2022]
Abstract
Alternative splicing in mRNA maturation has emerged as a major field of study also because of its implications in various diseases. The SR proteins play an important role in the regulation of this process. Evidence indicates that SRp20 (SFSR3), the smallest member of the SR protein family, is involved in numerous biological processes. Here we review the state-of-the-art of knowledge about the SR proteins, in particular SRp20, in terms of its function and misregulation in human diseases including cancer also in view of its potential as a therapeutic target.
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Sugiyama T, Sugioka-Sugiyama R, Hada K, Niwa R. Rhn1, a nuclear protein, is required for suppression of meiotic mRNAs in mitotically dividing fission yeast. PLoS One 2012; 7:e42962. [PMID: 22912768 PMCID: PMC3422304 DOI: 10.1371/journal.pone.0042962] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2012] [Accepted: 07/16/2012] [Indexed: 12/23/2022] Open
Abstract
In the fission yeast Schizosaccharomyces pombe, many meiotic mRNAs are transcribed during mitosis and meiosis and selectively eliminated in mitotic cells. However, this pathway for mRNA decay, called the determinant of selective removal (DSR)-Mmi1 system, targets only some of the numerous meiotic mRNAs that are transcribed in mitotic cells. Here we describe Rhn1, a nuclear protein involved in meiotic mRNA suppression in vegetative fission yeast. Rhn1 is homologous to budding yeast Rtt103 and localizes to one or a few discrete nuclear dots in growing vegetative cells. Rhn1 colocalizes with a pre-mRNA 3′-end processing factor, Pcf11, and with the 5′–3′ exoribonuclease, Dhp1; moreover, Rhn1 coimmunoprecipitates with Pcf11. Loss of rhn1 results in elevated sensitivity to high temperature, to thiabendazole (TBZ), and to UV. Interestingly, meiotic mRNAs—including moa1+, mcp5+, and mug96+—accumulate in mitotic rhn1Δ cells. Accumulation of meiotic mRNAs also occurs in strains lacking Lsk1, a kinase that phosphorylates serine 2 (Ser-2) in the C-terminal domain (CTD) of RNA polymerase II (Pol II), and in strains lacking Sen1, an ATP-dependent 5′–3′ RNA/DNA helicase: notably, both Lsk1 and Sen1 have been implicated in termination of Pol II-dependent transcription. Furthermore, RNAi knockdown of cids-2, a Caenorhabditis elegans ortholog of rhn1+, leads to elevated expression of a germline-specific gene, pgl-1, in somatic cells. These results indicate that Rhn1 contributes to the suppression of meiotic mRNAs in vegetative fission yeast and that the mechanism by which Rhn1 downregulates germline-specific transcripts may be conserved in unicellular and multicellular organisms.
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Affiliation(s)
- Tomoyasu Sugiyama
- Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan.
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Ni Z, Olsen JB, Guo X, Zhong G, Ruan ED, Marcon E, Young P, Guo H, Li J, Moffat J, Emili A, Greenblatt JF. Control of the RNA polymerase II phosphorylation state in promoter regions by CTD interaction domain-containing proteins RPRD1A and RPRD1B. Transcription 2012; 2:237-42. [PMID: 22231121 DOI: 10.4161/trns.2.5.17803] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
RNA polymerase II (RNAP II) C-terminal domain (CTD) phosphorylation is important for various transcription-related processes. Here, we identify by affinity purification and mass spectrometry three previously uncharacterized human CTD-interaction domain (CID)-containing proteins, RPRD1A, RPRD1B and RPRD2, which co-purify with RNAP II and three other RNAP II-associated proteins, RPAP2, GRINL1A and RECQL5, but not with the Mediator complex. RPRD1A and RPRD1B can accompany RNAP II from promoter regions to 3'-untranslated regions during transcription in vivo, predominantly interact with phosphorylated RNAP II, and can reduce CTD S5- and S7-phosphorylated RNAP II at target gene promoters. Thus, the RPRD proteins are likely to have multiple important roles in transcription.
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Affiliation(s)
- Zuyao Ni
- Banting and Best Department of Medical Research, University of Toronto, Toronto, Canada
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Möller A, Xie SQ, Hosp F, Lang B, Phatnani HP, James S, Ramirez F, Collin GB, Naggert JK, Babu MM, Greenleaf AL, Selbach M, Pombo A. Proteomic analysis of mitotic RNA polymerase II reveals novel interactors and association with proteins dysfunctional in disease. Mol Cell Proteomics 2012; 11:M111.011767. [PMID: 22199231 PMCID: PMC3433901 DOI: 10.1074/mcp.m111.011767] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2011] [Revised: 11/19/2011] [Indexed: 11/06/2022] Open
Abstract
RNA polymerase II (RNAPII) transcribes protein-coding genes in eukaryotes and interacts with factors involved in chromatin remodeling, transcriptional activation, elongation, and RNA processing. Here, we present the isolation of native RNAPII complexes using mild extraction conditions and immunoaffinity purification. RNAPII complexes were extracted from mitotic cells, where they exist dissociated from chromatin. The proteomic content of native complexes in total and size-fractionated extracts was determined using highly sensitive LC-MS/MS. Protein associations with RNAPII were validated by high-resolution immunolocalization experiments in both mitotic cells and in interphase nuclei. Functional assays of transcriptional activity were performed after siRNA-mediated knockdown. We identify >400 RNAPII associated proteins in mitosis, among these previously uncharacterized proteins for which we show roles in transcriptional elongation. We also identify, as novel functional RNAPII interactors, two proteins involved in human disease, ALMS1 and TFG, emphasizing the importance of gene regulation for normal development and physiology.
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Affiliation(s)
- André Möller
- From the ‡MRC Clinical Sciences Centre, Imperial College School of Medicine, Hammersmith Hospital Campus, London W12 0NN, United Kingdom
| | - Sheila Q. Xie
- From the ‡MRC Clinical Sciences Centre, Imperial College School of Medicine, Hammersmith Hospital Campus, London W12 0NN, United Kingdom
| | - Fabian Hosp
- §Max-Delbrück Center for Molecular Medicine, 13092 Berlin, Germany
| | - Benjamin Lang
- ¶MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, United Kingdom
| | - Hemali P. Phatnani
- ‖Department of Biochemistry, Duke University, Medical Center, Durham, North Carolina 27710
| | - Sonya James
- From the ‡MRC Clinical Sciences Centre, Imperial College School of Medicine, Hammersmith Hospital Campus, London W12 0NN, United Kingdom
| | | | | | | | - M. Madan Babu
- ¶MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, United Kingdom
| | - Arno L. Greenleaf
- ‖Department of Biochemistry, Duke University, Medical Center, Durham, North Carolina 27710
| | - Matthias Selbach
- §Max-Delbrück Center for Molecular Medicine, 13092 Berlin, Germany
| | - Ana Pombo
- From the ‡MRC Clinical Sciences Centre, Imperial College School of Medicine, Hammersmith Hospital Campus, London W12 0NN, United Kingdom
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Krzyszton M, Zakrzewska-Placzek M, Koper M, Kufel J. Rat1 and Xrn2: The Diverse Functions of the Nuclear Rat1/Xrn2 Exonuclease. EUKARYOTIC RNASES AND THEIR PARTNERS IN RNA DEGRADATION AND BIOGENESIS, PART A 2012; 31:131-63. [DOI: 10.1016/b978-0-12-404740-2.00007-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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Abstract
In most eukaryotes, the generation of the 3' end and transcription termination are initiated by cleavage of the pre-mRNA upstream of the polyadenylation site. This cleavage initiates 5'-3' degradation of the 3' end cleavage product by the exoribonuclease Rat1p leading to the dissociation of the RNA polymerase II (RNAPII) complex. The Rat1p-dependent transcription termination was also shown to be initiated by a polyadenylation-independent cleavage performed by the double-stranded RNA-specific ribonuclease (RNase) III (Rnt1p) suggesting that the majority of transcription termination events are RNase dependent. Therefore, it became essential for future studies on transcription termination to carefully consider both the nature of the RNase-dependent RNA transcripts and the association pattern of the RNAPII with the transcriptional unit. Here, we present methods allowing the evaluation of the impact of yeast RNases on the 3' end formation and their contribution to transcription termination. Northern blot analysis of transcripts generated downstream of known genes in the absence of RNases identifies potential transcription termination sites while chromatin immunoprecipitation of RNAPII differentiates between termination- and transcription-independent processing events.
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Allen MA, Hillier LW, Waterston RH, Blumenthal T. A global analysis of C. elegans trans-splicing. Genome Res 2010; 21:255-64. [PMID: 21177958 DOI: 10.1101/gr.113811.110] [Citation(s) in RCA: 129] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Trans-splicing of one of two short leader RNAs, SL1 or SL2, occurs at the 5' ends of pre-mRNAs of many C. elegans genes. We have exploited RNA-sequencing data from the modENCODE project to analyze the transcriptome of C. elegans for patterns of trans-splicing. Transcripts of ∼70% of genes are trans-spliced, similar to earlier estimates based on analysis of far fewer genes. The mRNAs of most trans-spliced genes are spliced to either SL1 or SL2, but most genes are not trans-spliced to both, indicating that SL1 and SL2 trans-splicing use different underlying mechanisms. SL2 trans-splicing occurs in order to separate the products of genes in operons genome wide. Shorter intercistronic distance is associated with greater use of SL2. Finally, increased use of SL1 trans-splicing to downstream operon genes can indicate the presence of an extra promoter in the intercistronic region, creating what has been termed a "hybrid" operon. Within hybrid operons the presence of the two promoters results in the use of the two SL classes: Transcription that originates at the promoter upstream of another gene creates a polycistronic pre-mRNA that receives SL2, whereas transcription that originates at the internal promoter creates transcripts that receive SL1. Overall, our data demonstrate that >17% of all C. elegans genes are in operons.
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Affiliation(s)
- Mary Ann Allen
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado at Boulder, Colorado 80309, USA
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Jia R, Li C, McCoy JP, Deng CX, Zheng ZM. SRp20 is a proto-oncogene critical for cell proliferation and tumor induction and maintenance. Int J Biol Sci 2010; 6:806-26. [PMID: 21179588 PMCID: PMC3005347 DOI: 10.7150/ijbs.6.806] [Citation(s) in RCA: 158] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2010] [Accepted: 12/13/2010] [Indexed: 01/17/2023] Open
Abstract
Tumor cells display a different profile of gene expression than their normal counterparts. Perturbations in the levels of cellular splicing factors can alter gene expression, potentially leading to tumorigenesis. We found that splicing factor SRp20 (SFRS3) is highly expressed in cancers. SRp20 regulated the expression of Forkhead box transcription factor M1 (FoxM1) and two of its transcriptional targets, PLK1 and Cdc25B, and controlled cell cycle progression and proliferation. Cancer cells with RNAi-mediated reduction of SRp20 expression exhibited G2/M arrest, growth retardation, and apoptosis. Increased SRp20 expression in rodent fibroblasts promoted immortal cell growth and transformation. More importantly, we found that SRp20 promoted tumor induction and the maintenance of tumor growth in nude mice and rendered immortal rodent fibroblasts tumorigenic. Collectively, these results suggest that increased SRp20 expression in tumor cells is a critical step for tumor initiation, progression, and maintenance.
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Affiliation(s)
- Rong Jia
- Tumor Virus RNA Biology Laboratory, HIV and AIDS Malignancy Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
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de Almeida SF, García-Sacristán A, Custódio N, Carmo-Fonseca M. A link between nuclear RNA surveillance, the human exosome and RNA polymerase II transcriptional termination. Nucleic Acids Res 2010; 38:8015-26. [PMID: 20699273 PMCID: PMC3001075 DOI: 10.1093/nar/gkq703] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
In eukaryotes, the production of mature messenger RNA that exits the nucleus to be translated into protein in the cytoplasm requires precise and extensive modification of the nascent transcript. Any failure that compromises the integrity of an mRNA may cause its retention in the nucleus and trigger its degradation. Multiple studies indicate that mRNAs with processing defects accumulate in nuclear foci or ‘dots’ located near the site of transcription, but how exactly are defective RNAs recognized and tethered is still unknown. Here, we present evidence suggesting that unprocessed β-globin transcripts render RNA polymerase II (Pol II) incompetent for termination and that this quality control process requires the integrity of the nuclear exosome. Our results show that unprocessed pre-mRNAs remain tethered to the DNA template in association with Pol II, in an Rrp6-dependent manner. This reveals an unprecedented link between nuclear RNA surveillance, the exosome and Pol II transcriptional termination.
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Affiliation(s)
- Sérgio F de Almeida
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisboa, Portugal
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Van Epps H, Dai Y, Qi Y, Goncharov A, Jin Y. Nuclear pre-mRNA 3'-end processing regulates synapse and axon development in C. elegans. Development 2010; 137:2237-50. [PMID: 20530551 DOI: 10.1242/dev.049692] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Nuclear pre-mRNA 3'-end processing is vital for the production of mature mRNA and the generation of the 3' untranslated region (UTR). However, the roles and regulation of this event in cellular development remain poorly understood. Here, we report the function of a nuclear pre-mRNA 3'-end processing pathway in synapse and axon formation in C. elegans. In a genetic enhancer screen for synaptogenesis mutants, we identified a novel polyproline-rich protein, Synaptic defective enhancer-1 (SYDN-1). Loss of function of sydn-1 causes abnormal synapse and axon development, and displays striking synergistic interactions with several genes that regulate specific aspects of synapses. SYDN-1 is required in neurons and localizes to distinct regions of the nucleus. Through a genetic suppressor screen, we found that the neuronal defects of sydn-1 mutants are suppressed by loss of function in Polyadenylation factor subunit-2 (PFS-2), a conserved WD40-repeat protein that interacts with multiple subcomplexes of the pre-mRNA 3'-end processing machinery. PFS-2 partially colocalizes with SYDN-1, and SYDN-1 influences the nuclear abundance of PFS-2. Inactivation of several members of the nuclear 3'-end processing complex suppresses sydn-1 mutants. Furthermore, lack of sydn-1 can increase the activity of 3'-end processing. Our studies provide in vivo evidence for pre-mRNA 3'-end processing in synapse and axon development and identify SYDN-1 as a negative regulator of this cellular event in neurons.
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Affiliation(s)
- Heather Van Epps
- Division of Biological Sciences, Section of Neurobiology, University of California, San Diego, CA 92093, USA
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Millevoi S, Vagner S. Molecular mechanisms of eukaryotic pre-mRNA 3' end processing regulation. Nucleic Acids Res 2009; 38:2757-74. [PMID: 20044349 PMCID: PMC2874999 DOI: 10.1093/nar/gkp1176] [Citation(s) in RCA: 303] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Messenger RNA (mRNA) 3′ end formation is a nuclear process through which all eukaryotic primary transcripts are endonucleolytically cleaved and most of them acquire a poly(A) tail. This process, which consists in the recognition of defined poly(A) signals of the pre-mRNAs by a large cleavage/polyadenylation machinery, plays a critical role in gene expression. Indeed, the poly(A) tail of a mature mRNA is essential for its functions, including stability, translocation to the cytoplasm and translation. In addition, this process serves as a bridge in the network connecting the different transcription, capping, splicing and export machineries. It also participates in the quantitative and qualitative regulation of gene expression in a variety of biological processes through the selection of single or alternative poly(A) signals in transcription units. A large number of protein factors associates with this machinery to regulate the efficiency and specificity of this process and to mediate its interaction with other nuclear events. Here, we review the eukaryotic 3′ end processing machineries as well as the comprehensive set of regulatory factors and discuss the different molecular mechanisms of 3′ end processing regulation by proposing several overlapping models of regulation.
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Affiliation(s)
- Stefania Millevoi
- Institut National de la Santé et de la Recherche Médicale U563, Toulouse, F-31000, France.
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Hockert JA, Yeh HJ, MacDonald CC. The hinge domain of the cleavage stimulation factor protein CstF-64 is essential for CstF-77 interaction, nuclear localization, and polyadenylation. J Biol Chem 2009; 285:695-704. [PMID: 19887456 DOI: 10.1074/jbc.m109.061705] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Because polyadenylation is essential for cell growth, in vivo examination of polyadenylation protein function has been difficult. Here we describe a new in vivo assay that allows structure-function assays on CstF-64, a protein that binds to pre-mRNAs downstream of the cleavage site for accurate and efficient polyadenylation. In this assay (the stem-loop luciferase assay for polyadenylation, SLAP), expression of a luciferase pre-mRNA with a modified downstream sequence element was made dependent upon co-expression of an MS2-CstF-64 fusion protein. We show here that SLAP accurately reflects CstF-64-dependent polyadenylation, confirming the validity of this assay. Using SLAP, we determined that CstF-64 domains involved in RNA binding, interaction with CstF-77 (the "Hinge" domain), and coupling to transcription are critical for polyadenylation. Further, we showed that the Hinge domain is necessary for CstF-64 interaction with CstF-77 and consequent nuclear localization, suggesting that nuclear import of a preformed CstF complex is an essential step in polyadenylation.
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Affiliation(s)
- J Andrew Hockert
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, Texas 79430-6540, USA
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47
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Richard P, Manley JL. Transcription termination by nuclear RNA polymerases. Genes Dev 2009; 23:1247-69. [PMID: 19487567 DOI: 10.1101/gad.1792809] [Citation(s) in RCA: 252] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Gene transcription in the cell nucleus is a complex and highly regulated process. Transcription in eukaryotes requires three distinct RNA polymerases, each of which employs its own mechanisms for initiation, elongation, and termination. Termination mechanisms vary considerably, ranging from relatively simple to exceptionally complex. In this review, we describe the present state of knowledge on how each of the three RNA polymerases terminates and how mechanisms are conserved, or vary, from yeast to human.
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Affiliation(s)
- Patricia Richard
- Department of Biological Sciences, Columbia University, New York, New York 10027, USA
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Karakuzu O, Wang DP, Cameron S. MIG-32 and SPAT-3A are PRC1 homologs that control neuronal migration in Caenorhabditis elegans. Development 2009; 136:943-53. [PMID: 19211678 PMCID: PMC2727560 DOI: 10.1242/dev.029363] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/09/2009] [Indexed: 11/20/2022]
Abstract
The Polycomb repression complex 2 (PRC2) methylates histone H3 lysine 27 at target genes to modify gene expression, and this mark is recognized by PRC1, which ubiquitylates histone H2A. In Caenorhabditis elegans, a complex of the MES-2, MES-3 and MES-6 proteins is functionally analogous to the PRC2 complex, but the functional analog of PRC1, and indeed whether C. elegans has such a complex, has been unclear. We describe here that MIG-32 and SPAT-3A are functional analogs of PRC1 in C. elegans, where they are required for neuronal migrations and during vulval development. mig-32 and spat-3 mutants are defective in H2A ubiquitylation, and have nervous system defects that partially overlap with those of mes mutants. However, unlike the mes mutants, mig-32 and spat-3 mutants are fertile, suggesting that PRC1 function is not absolutely required in the germline for essential functions of PRC2.
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Affiliation(s)
- Ozgur Karakuzu
- Department of Pediatrics, Division of Pediatric Hematology-Oncology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390, USA
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