1
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Paul T, Zhang P, Zhang Z, Fargason T, De Silva NIU, Powell E, Ekpenyong E, Jamal S, Yu Y, Prevelige P, Lu R, Zhang J. The U1-70K and SRSF1 interaction is modulated by phosphorylation during the early stages of spliceosome assembly. Protein Sci 2024; 33:e5117. [PMID: 39023093 PMCID: PMC11255866 DOI: 10.1002/pro.5117] [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: 03/25/2024] [Revised: 06/22/2024] [Accepted: 07/01/2024] [Indexed: 07/20/2024]
Abstract
In eukaryotes, pre-mRNA splicing is vital for RNA processing and orchestrated by the spliceosome, whose assembly starts with the interaction between U1-70K and SR proteins. Despite the significance of the U1-70K/SR interaction, the dynamic nature of the complex and the challenges in obtaining soluble U1-70K have impeded a comprehensive understanding of the interaction at the structural level for decades. We overcome the U1-70K solubility issues, enabling us to characterize the interaction between U1-70K and SRSF1, a representative SR protein. We unveil specific interactions: phosphorylated SRSF1 RS with U1-70K BAD1, and SRSF1 RRM1 with U1-70K RRM. The RS/BAD1 interaction plays a dominant role, whereas the interaction between the RRM domains further enhances the stability of the U1-70K/SRSF1 complex. The RRM interaction involves the C-terminal extension of U1-70K RRM and the conserved acid patches on SRSF1 RRM1 that is involved in SRSF1 phase separation. Our circular dichroism spectra reveal that BAD1 adapts an α-helical conformation and RS is intrinsically disordered. Intriguingly, BAD1 undergoes a conformation switch from α-helix to β-strand and random coil upon RS binding. In addition to the regulatory mechanism via SRSF1 phosphorylation, the U1-70K/SRSF1 interaction is also regulated by U1-70K BAD1 phosphorylation. We find that U1-70K phosphorylation inhibits the U1-70K and SRSF1 interaction. Our structural findings are validated through in vitro splicing assays and in-cell saturated domain scanning using the CRISPR method, providing new insights into the intricate regulatory mechanisms of pre-mRNA splicing.
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Affiliation(s)
- Trent Paul
- Department of ChemistryUniversity of Alabama at BirminghamBirminghamAlabamaUSA
| | - Pengcheng Zhang
- Department of Medicine, Division of Hematology/OncologyUniversity of Alabama at BirminghamBirminghamAlabamaUSA
| | - Zihan Zhang
- Department of ChemistryUniversity of Alabama at BirminghamBirminghamAlabamaUSA
| | - Talia Fargason
- Department of ChemistryUniversity of Alabama at BirminghamBirminghamAlabamaUSA
| | | | - Erin Powell
- Department of ChemistryUniversity of Alabama at BirminghamBirminghamAlabamaUSA
| | - Ethan Ekpenyong
- Department of ChemistryUniversity of Alabama at BirminghamBirminghamAlabamaUSA
| | - Shariq Jamal
- Department of ChemistryUniversity of Alabama at BirminghamBirminghamAlabamaUSA
| | - Yanbao Yu
- Department of Chemistry and BiochemistryUniversity of DelawareNewarkDelawareUSA
| | - Peter Prevelige
- Department of MicrobiologyUniversity of Alabama at BirminghamBirminghamAlabamaUSA
| | - Rui Lu
- Department of Medicine, Division of Hematology/OncologyUniversity of Alabama at BirminghamBirminghamAlabamaUSA
| | - Jun Zhang
- Department of ChemistryUniversity of Alabama at BirminghamBirminghamAlabamaUSA
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2
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Liao SE, Sudarshan M, Regev O. Deciphering RNA splicing logic with interpretable machine learning. Proc Natl Acad Sci U S A 2023; 120:e2221165120. [PMID: 37796983 PMCID: PMC10576025 DOI: 10.1073/pnas.2221165120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Accepted: 08/29/2023] [Indexed: 10/07/2023] Open
Abstract
Machine learning methods, particularly neural networks trained on large datasets, are transforming how scientists approach scientific discovery and experimental design. However, current state-of-the-art neural networks are limited by their uninterpretability: Despite their excellent accuracy, they cannot describe how they arrived at their predictions. Here, using an "interpretable-by-design" approach, we present a neural network model that provides insights into RNA splicing, a fundamental process in the transfer of genomic information into functional biochemical products. Although we designed our model to emphasize interpretability, its predictive accuracy is on par with state-of-the-art models. To demonstrate the model's interpretability, we introduce a visualization that, for any given exon, allows us to trace and quantify the entire decision process from input sequence to output splicing prediction. Importantly, the model revealed uncharacterized components of the splicing logic, which we experimentally validated. This study highlights how interpretable machine learning can advance scientific discovery.
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Affiliation(s)
- Susan E. Liao
- Department of Computer Science, Courant Institute of Mathematical Sciences, New York University, New York, NY10012
| | - Mukund Sudarshan
- Department of Computer Science, Courant Institute of Mathematical Sciences, New York University, New York, NY10012
| | - Oded Regev
- Department of Computer Science, Courant Institute of Mathematical Sciences, New York University, New York, NY10012
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3
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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: 2.0] [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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4
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Le MN, Nguyen TD, Nguyen TA. SRSF7 and SRSF3 depend on RNA sequencing motifs and secondary structures to regulate Microprocessor. Life Sci Alliance 2023; 6:e202201779. [PMID: 36750366 PMCID: PMC9905709 DOI: 10.26508/lsa.202201779] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Revised: 01/25/2023] [Accepted: 01/26/2023] [Indexed: 02/09/2023] Open
Abstract
Human Microprocessor cleaves pri-miRNAs to initiate miRNA biogenesis. The accuracy and efficiency of Microprocessor cleavage ensure appropriate miRNA sequence and expression and thus its proper gene regulation. However, Microprocessor cleaves many pri-miRNAs incorrectly, so it requires assistance from many cofactors. For example, SRSF3 enhances Microprocessor cleavage by interacting with the CNNC motif in pri-miRNAs. However, whether SRSF3 can function with other motifs and/or requires the motifs in a certain secondary structure is unknown. In addition, the function of SRSF7 (a paralog of SRSF3) in miRNA biogenesis still needs to be discovered. Here, we demonstrated that SRSF7 could stimulate Microprocessor cleavage. In addition, by conducting high-throughput pri-miRNA cleavage assays for Microprocessor and SRSF7 or SRSF3, we demonstrated that SRSF7 and SRSF3 function with the CRC and CNNC motifs, adopting certain secondary structures. In addition, SRSF7 and SRSF3 affect the Microprocessor cleavage sites in human cells. Our findings demonstrate the roles of SRSF7 in miRNA biogenesis and provide a comprehensive view of the molecular mechanism of SRSF7 and SRSF3 in enhancing Microprocessor cleavage.
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Affiliation(s)
- Minh Ngoc Le
- Division of Life Science, The Hong Kong University of Science & Technology, Hong Kong, China
| | - Trung Duc Nguyen
- Division of Life Science, The Hong Kong University of Science & Technology, Hong Kong, China
| | - Tuan Anh Nguyen
- Division of Life Science, The Hong Kong University of Science & Technology, Hong Kong, China
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5
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Cooperative Binding of SRSF3 to Structured 3'ss-α Exon RNA during α Exon Inclusion in the ZO-1 mRNA. Curr Issues Mol Biol 2023; 45:593-603. [PMID: 36661525 PMCID: PMC9857539 DOI: 10.3390/cimb45010039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Revised: 12/28/2022] [Accepted: 01/03/2023] [Indexed: 01/11/2023] Open
Abstract
ZO-1α+ and ZO-1α- proteins are expressed in hermetic and leaky tight junctions, respectively. Two cis-acting distant exonic elements partly activate the 240 nucleotide-long α exon producing the ZO-1α+ isoform. However, the elements within and around the α exon and their respective factors involved in its splicing are unknown. To study the dynamic interaction between SRSF3 and its bioinformatically predicted target sites around the 3'ss upstream of the α exon during its activation, we performed EMSA, crosslinking, and in vivo splicing assays by ZO-1 minigene expression and siRNA-mediated silencing in transfected cells. Using V1 RNase, we probed the possible formation of a hairpin RNA structure between the intronic and proximal exonic SRSF3 binding sites. The hairpin sufficed for complex formations in the EMSA. The interaction of SRSF3 with the intronic site promoted the cooperative binding of SRSF3 to the exonic site. Finally, SRSF3 restored α exon activation in SRSF3 knockdown transfectants. Altogether, our results show that SRSF3-hairpin RNA interaction is crucial in the early recognition of 3'ss for α exon activation. It remains to be explored whether SRSF3 recruits or stabilizes the binding of other factors or brings separate splice sites into proximity.
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6
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Chen QW, Cai QQ, Yang Y, Dong S, Liu YY, Chen ZY, Kang CL, Qi B, Dong YW, Wu W, Zhuang LP, Shen YH, Meng ZQ, Wu XZ. LncRNA BC promotes lung adenocarcinoma progression by modulating IMPAD1 alternative splicing. Clin Transl Med 2023; 13:e1129. [PMID: 36650118 PMCID: PMC9845120 DOI: 10.1002/ctm2.1129] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2022] [Revised: 11/14/2022] [Accepted: 11/17/2022] [Indexed: 01/19/2023] Open
Abstract
BACKGROUND The therapeutic value of targeted therapies in patients with lung cancer is reduced when tumours acquire secondary resistance after an initial period of successful treatment. However, the molecular events behind the resistance to targeted therapies in lung cancer remain largely unknown. AIMS To discover the important role and mechanism of lncRNA BC in promoting tumor metastasis and influencing clinical prognosis of LUAD. MATERIALS & METHODS Microarrays were used to screen a comprehensive set of lncRNAs with differential expression profiles in lung cancer cells. The functional role and mechanism of lncRNA were further investigated by gain- and loss-of-function assays. RNA pull-down, protein assays, and mass spectrometry were used to identify proteins that interacted with lncRNA. TaqMan PCR was used to measure lncRNA in lung adenocarcinoma and adjacent nontumor tissues from 428 patients. The clinical significance of lncRNA identified was statistically confirmed in this cohort of patients. RESULTS In this study, we show that the long non-coding RNA BC009639 (BC) is involved in acquired resistance to EGFR-targeted therapies. Among the 235 long non-coding RNAs that were differentially expressed in lung cancer cell lines, with different metastatic potentials, BC promoted growth, invasion, metastasis, and resistance to EGFR-tyrosine kinase inhibitors (EGFR-TKIs), both in vitro and in vivo. BC was highly expressed in 428 patients with lung adenocarcinoma (LUAD) and high BC expression correlated with reduced efficacy of EGFR-TKI therapy. To uncover the molecular mechanism of BC-mediated EGFR-TKI resistance in lung cancer, we screened and identified nucleolin and hnRNPK that interact with BC. BC formed the splicing complex with nucleolin and hnRNPK to facilitate the production of a non-protein-coding inositol monophosphatase domain containing 1 (IMPAD1) splice variant, instead of the protein-coding variant. The BC-mediated alternative splicing (AS) of IMPAD1 resulted in the induction of the epithelial-mesenchymal transition and resistance to EGFR-TKI in lung cancer. High BC expression correlated with clinical progress and poor survival among 402 patients with LUAD. DISSCUSSION Through alternative splicing, BC boosted the non-coding IMPAD1-203 transcript variant while suppressing the IMPAD1-201 variant. In order to control the processing of pre-mRNA, BC not only attracted RNA binding proteins (NCL, IGF2BP1) or splicing factors (hnRNPK), but also controlled the formation of the splicing-regulator complex by creating RNA-RNA-duplexes. CONCLUSION Our results reveal an important role for BC in mediating resistance to EGFR-targeted therapy in LUAD through IMPAD1 AS and in implication for the targeted therapy resistance.
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Affiliation(s)
- Qi Wen Chen
- Department of Integrative OncologyFudan University Shanghai Cancer CenterShanghaiP. R. China
- Department of Oncology, Shanghai Medical CollegeFudan UniversityShanghaiP. R. China
| | - Qian Qian Cai
- Shanghai Key Laboratory of Molecular ImagingShanghai University of Medicine and Health SciencesShanghaiP. R. China
| | - Ying Yang
- Key Laboratory of Glycoconjugate Research Ministry of Public Health, Department of Biochemistry and Molecular Biology, School of Basic Medical SciencesFudan UniversityShanghaiP. R. China
| | - Shu Dong
- Department of Integrative OncologyFudan University Shanghai Cancer CenterShanghaiP. R. China
- Department of Oncology, Shanghai Medical CollegeFudan UniversityShanghaiP. R. China
| | - Yuan Yuan Liu
- Key Laboratory of Glycoconjugate Research Ministry of Public Health, Department of Biochemistry and Molecular Biology, School of Basic Medical SciencesFudan UniversityShanghaiP. R. China
| | - Zhong Yi Chen
- Key Laboratory of Glycoconjugate Research Ministry of Public Health, Department of Biochemistry and Molecular Biology, School of Basic Medical SciencesFudan UniversityShanghaiP. R. China
| | - Chun Lan Kang
- Key Laboratory of Glycoconjugate Research Ministry of Public Health, Department of Biochemistry and Molecular Biology, School of Basic Medical SciencesFudan UniversityShanghaiP. R. China
| | - Bing Qi
- Key Laboratory of Glycoconjugate Research Ministry of Public Health, Department of Biochemistry and Molecular Biology, School of Basic Medical SciencesFudan UniversityShanghaiP. R. China
| | - Yi Wei Dong
- Key Laboratory of Glycoconjugate Research Ministry of Public Health, Department of Biochemistry and Molecular Biology, School of Basic Medical SciencesFudan UniversityShanghaiP. R. China
| | - Wei Wu
- Department of PathologyShanghai Pulmonary Hospital, Tongji University School of MedicineShanghaiP. R. China
| | - Li Ping Zhuang
- Department of Integrative OncologyFudan University Shanghai Cancer CenterShanghaiP. R. China
- Department of Oncology, Shanghai Medical CollegeFudan UniversityShanghaiP. R. China
| | - Ye Hua Shen
- Department of Integrative OncologyFudan University Shanghai Cancer CenterShanghaiP. R. China
- Department of Oncology, Shanghai Medical CollegeFudan UniversityShanghaiP. R. China
| | - Zhi Qiang Meng
- Department of Integrative OncologyFudan University Shanghai Cancer CenterShanghaiP. R. China
- Department of Oncology, Shanghai Medical CollegeFudan UniversityShanghaiP. R. China
| | - Xing Zhong Wu
- Key Laboratory of Glycoconjugate Research Ministry of Public Health, Department of Biochemistry and Molecular Biology, School of Basic Medical SciencesFudan UniversityShanghaiP. R. China
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7
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De Silva NIU, Fargason T, Zhang Z, Wang T, Zhang J. Inter-domain Flexibility of Human Ser/Arg-Rich Splicing Factor 1 Allows Variable Spacer Length in Cognate RNA’s Bipartite Motifs. Biochemistry 2022; 61:2922-2932. [DOI: 10.1021/acs.biochem.2c00565] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Affiliation(s)
- Naiduwadura Ivon Upekala De Silva
- Department of Chemistry, College of Arts and Sciences, University of Alabama at Birmingham, CH266, 901 14th Street South, Birmingham, Alabama35294-1240, United States
| | - Talia Fargason
- Department of Chemistry, College of Arts and Sciences, University of Alabama at Birmingham, CH266, 901 14th Street South, Birmingham, Alabama35294-1240, United States
| | - Zihan Zhang
- Department of Chemistry, College of Arts and Sciences, University of Alabama at Birmingham, CH266, 901 14th Street South, Birmingham, Alabama35294-1240, United States
| | - Ting Wang
- Department of Chemistry, College of Arts and Sciences, University of Alabama at Birmingham, CH266, 901 14th Street South, Birmingham, Alabama35294-1240, United States
| | - Jun Zhang
- Department of Chemistry, College of Arts and Sciences, University of Alabama at Birmingham, CH266, 901 14th Street South, Birmingham, Alabama35294-1240, United States
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8
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Das R, Jakubowski MA, Spildener J, Cheng YW. Identification of Novel MET Exon 14 Skipping Variants in Non-Small Cell Lung Cancer Patients: A Prototype Workflow Involving in Silico Prediction and RT-PCR. Cancers (Basel) 2022; 14:cancers14194814. [PMID: 36230737 PMCID: PMC9563401 DOI: 10.3390/cancers14194814] [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: 06/30/2022] [Revised: 09/11/2022] [Accepted: 09/22/2022] [Indexed: 11/16/2022] Open
Abstract
Background and aims: The MET exon 14 skipping (METex14) is an oncogenic driver mutation that provides a therapeutic opportunity in non-small cell lung cancer (NSCLCs) patients. This event often results from sequence changes at the MET canonical splicing sites. We characterize two novel non-canonical splicing site variants of MET that produce METex14. Materials and Methods: Two variants were identified in three advanced-stage NSCLC patients in a next-generation sequencing panel. The potential impact on splicing was predicted using in silico tools. METex14 mutation was confirmed using reverse transcription (RT)-PCR and a Sanger sequencing analysis on RNA extracted from stained cytology smears. Results: The interrogated MET (RefSeq ID NM_000245.3) variants include a single nucleotide substitution, c.3028+3A>T, in intron 14 and a deletion mutation, c.3012_3028del, in exon 14. The in silico prediction analysis exhibited reduced splicing strength in both variants compared with the MET normal transcript. The RT-PCR and subsequent Sanger sequencing analyses confirmed METex14 skipping in all three patients carrying these variants. Conclusion: This study reveals two non-canonical MET splice variants that cause exon 14 skipping, concurrently also proposes a clinical workflow for the classification of such non-canonical splicing site variants detected by routine DNA-based NGS test. It shows the usefulness of in silico prediction to identify potential METex14 driver mutation and exemplifies the opportunity of routine cytology slides for RNA-based testing.
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Affiliation(s)
| | | | | | - Yu-Wei Cheng
- Correspondence: ; Tel.: +1-216-445-0757; Fax: +1-216-445-0681
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9
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Chen H, Lv L, Liang R, Guo W, Liao Z, Chen Y, Zhu K, Huang R, Zhao H, Pu Q, Yuan Z, Zeng Z, Zheng X, Feng S, Qi X, Cai D. miR-486 improves fibrotic activity in myocardial infarction by targeting SRSF3/p21-Mediated cardiac myofibroblast senescence. J Cell Mol Med 2022; 26:5135-5149. [PMID: 36117396 PMCID: PMC9575141 DOI: 10.1111/jcmm.17539] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Revised: 08/08/2022] [Accepted: 08/26/2022] [Indexed: 12/03/2022] Open
Abstract
The regulation of fibrotic activities is key to improving pathological remodelling post‐myocardial infarction (MI). Currently, in the clinic, safe and curative therapies for cardiac fibrosis and improvement of the pathological fibrotic environment, scar formation and pathological remodelling post‐MI are lacking. Previous studies have shown that miR‐486 is involved in the regulation of fibrosis. However, it is still unclear how miR‐486 functions in post‐MI regeneration. Here, we first demonstrated that miR‐486 targeting SRSF3/p21 mediates the senescence of cardiac myofibroblasts to improve their fibrotic activity, which benefits the regeneration of MI by limiting scar size and post‐MI remodelling. miR‐486‐targeted silencing has high potential as a novel target to improve fibrotic activity, cardiac fibrosis and pathological remodelling.
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Affiliation(s)
- Hongyi Chen
- Key Laboratory of Regenerative Medicine, Ministry of Education, Jinan University, Guangzhou, China.,Joint Laboratory for Regenerative Medicine, Chinese University of Hong Kong-Jinan University, Guangzhou, China.,International Base of Collaboration for Science and Technology (JNU), Ministry of Science and Technology, Guangzhou, China.,Department of Developmental and Regenerative Biology, Jinan University, Guangzhou, China
| | - Luocheng Lv
- Key Laboratory of Regenerative Medicine, Ministry of Education, Jinan University, Guangzhou, China.,Joint Laboratory for Regenerative Medicine, Chinese University of Hong Kong-Jinan University, Guangzhou, China.,International Base of Collaboration for Science and Technology (JNU), Ministry of Science and Technology, Guangzhou, China.,Department of Developmental and Regenerative Biology, Jinan University, Guangzhou, China
| | - Ruoxu Liang
- Key Laboratory of Regenerative Medicine, Ministry of Education, Jinan University, Guangzhou, China.,Joint Laboratory for Regenerative Medicine, Chinese University of Hong Kong-Jinan University, Guangzhou, China.,International Base of Collaboration for Science and Technology (JNU), Ministry of Science and Technology, Guangzhou, China.,Department of Developmental and Regenerative Biology, Jinan University, Guangzhou, China
| | - Weimin Guo
- Key Laboratory of Regenerative Medicine, Ministry of Education, Jinan University, Guangzhou, China.,Joint Laboratory for Regenerative Medicine, Chinese University of Hong Kong-Jinan University, Guangzhou, China.,International Base of Collaboration for Science and Technology (JNU), Ministry of Science and Technology, Guangzhou, China.,Department of Developmental and Regenerative Biology, Jinan University, Guangzhou, China
| | - Zhaofu Liao
- Key Laboratory of Regenerative Medicine, Ministry of Education, Jinan University, Guangzhou, China.,Joint Laboratory for Regenerative Medicine, Chinese University of Hong Kong-Jinan University, Guangzhou, China.,International Base of Collaboration for Science and Technology (JNU), Ministry of Science and Technology, Guangzhou, China.,Department of Developmental and Regenerative Biology, Jinan University, Guangzhou, China
| | - Yilin Chen
- Key Laboratory of Regenerative Medicine, Ministry of Education, Jinan University, Guangzhou, China.,Joint Laboratory for Regenerative Medicine, Chinese University of Hong Kong-Jinan University, Guangzhou, China.,International Base of Collaboration for Science and Technology (JNU), Ministry of Science and Technology, Guangzhou, China.,Department of Developmental and Regenerative Biology, Jinan University, Guangzhou, China
| | - Kuikui Zhu
- Key Laboratory of Regenerative Medicine, Ministry of Education, Jinan University, Guangzhou, China.,Joint Laboratory for Regenerative Medicine, Chinese University of Hong Kong-Jinan University, Guangzhou, China.,International Base of Collaboration for Science and Technology (JNU), Ministry of Science and Technology, Guangzhou, China.,Department of Developmental and Regenerative Biology, Jinan University, Guangzhou, China
| | - Ruijin Huang
- Institute of Anatomy, Department of Neuroanatomy, Medical Faculty, University of Bonn, Germany
| | - Hui Zhao
- Stem Cell and Regeneration TRP, School of Biomedical Sciences, Chinese University of Hong Kong, Hong Kong
| | - Qin Pu
- Institute of Anatomy, Department of Neuroanatomy, Medical Faculty, University of Bonn, Germany
| | - Ziqiang Yuan
- Cancer Institute of New Jersey, Department of Medical Oncology, Robert Wood Johnson of Medical School, USA
| | - Zhaohua Zeng
- Division of Cardiology, Department of Internal Medicine, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
| | - Xin Zheng
- Key Laboratory of Regenerative Medicine, Ministry of Education, Jinan University, Guangzhou, China.,Joint Laboratory for Regenerative Medicine, Chinese University of Hong Kong-Jinan University, Guangzhou, China.,International Base of Collaboration for Science and Technology (JNU), Ministry of Science and Technology, Guangzhou, China.,Department of Developmental and Regenerative Biology, Jinan University, Guangzhou, China
| | - Shanshan Feng
- Key Laboratory of Regenerative Medicine, Ministry of Education, Jinan University, Guangzhou, China.,Joint Laboratory for Regenerative Medicine, Chinese University of Hong Kong-Jinan University, Guangzhou, China.,International Base of Collaboration for Science and Technology (JNU), Ministry of Science and Technology, Guangzhou, China.,Department of Developmental and Regenerative Biology, Jinan University, Guangzhou, China
| | - Xufeng Qi
- Key Laboratory of Regenerative Medicine, Ministry of Education, Jinan University, Guangzhou, China.,Joint Laboratory for Regenerative Medicine, Chinese University of Hong Kong-Jinan University, Guangzhou, China.,International Base of Collaboration for Science and Technology (JNU), Ministry of Science and Technology, Guangzhou, China.,Department of Developmental and Regenerative Biology, Jinan University, Guangzhou, China
| | - Dongqing Cai
- Key Laboratory of Regenerative Medicine, Ministry of Education, Jinan University, Guangzhou, China.,Joint Laboratory for Regenerative Medicine, Chinese University of Hong Kong-Jinan University, Guangzhou, China.,International Base of Collaboration for Science and Technology (JNU), Ministry of Science and Technology, Guangzhou, China.,Department of Developmental and Regenerative Biology, Jinan University, Guangzhou, China
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10
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Chen X, Yin J, Cao D, Xiao D, Zhou Z, Liu Y, Shou W. The Emerging Roles of the RNA Binding Protein QKI in Cardiovascular Development and Function. Front Cell Dev Biol 2021; 9:668659. [PMID: 34222237 PMCID: PMC8242579 DOI: 10.3389/fcell.2021.668659] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Accepted: 05/10/2021] [Indexed: 12/30/2022] Open
Abstract
RNA binding proteins (RBPs) have a broad biological and physiological function and are critical in regulating pre-mRNA posttranscriptional processing, intracellular migration, and mRNA stability. QKI, also known as Quaking, is a member of the signal transduction and activation of RNA (STAR) family, which also belongs to the heterogeneous nuclear ribonucleoprotein K- (hnRNP K-) homology domain protein family. There are three major alternatively spliced isoforms, QKI-5, QKI-6, and QKI-7, differing in carboxy-terminal domains. They share a common RNA binding property, but each isoform can regulate pre-mRNA splicing, transportation or stability differently in a unique cell type-specific manner. Previously, QKI has been known for its important role in contributing to neurological disorders. A series of recent work has further demonstrated that QKI has important roles in much broader biological systems, such as cardiovascular development, monocyte to macrophage differentiation, bone metabolism, and cancer progression. In this mini-review, we will focus on discussing the emerging roles of QKI in regulating cardiac and vascular development and function and its potential link to cardiovascular pathophysiology.
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Affiliation(s)
- Xinyun Chen
- Department of Pediatrics, Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, IN, United States
- Guangdong Key Laboratory for Genome Stability and Human Disease Prevention, Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Shenzhen University, Shenzhen, China
| | - Jianwen Yin
- Department of Foot, Ankle and Hand Surgery, Shenzhen Second People’s Hospital, First Affiliated Hospital of Shenzhen University, Shenzhen, China
| | - Dayan Cao
- Department of Pediatrics, Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, IN, United States
| | - Deyong Xiao
- Department of Pediatrics, Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, IN, United States
| | - Zhongjun Zhou
- Faculty of Medicine, School of Biomedical Sciences, The University of Hong Kong, Hong Kong
| | - Ying Liu
- Department of Pediatrics, Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, IN, United States
| | - Weinian Shou
- Department of Pediatrics, Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, IN, United States
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11
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Nakura T, Ozoe A, Narita Y, Matsuo M, Hakuno F, Kataoka N, Takahashi SI. Rbfox2 mediates exon 11 inclusion in insulin receptor pre-mRNA splicing in hepatoma cells. Biochimie 2021; 187:25-32. [PMID: 34022289 DOI: 10.1016/j.biochi.2021.05.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 05/10/2021] [Accepted: 05/14/2021] [Indexed: 11/27/2022]
Abstract
Insulin receptor (IR) pre-mRNA undergoes alternative splicing that produces two isoforms, IR-A and IR-B. The ratio of IR-A to IR-B varies among tissues, which strongly suggests that IR mRNA alternative splicing is regulated in a tissue-specific manner. However, the precise molecular mechanism for IR alternative splicing remains to be elucidated, especially in liver. In this study, we have analyzed IR alternative splicing mechanism by preparing a mini-gene splicing reporter with rat genomic DNA. The splicing reporter that contains exon 11 and its flanking intronic sequences could reproduce alternative splicing pattern in rat hepatoma H4IIE cells. Introducing several deletions in introns of the reporter revealed that intron 11 contains the region near exon 11 essential to promote exon 11 inclusion. This region contains an UGCAUG sequence, a specific binding site for the Rbfox splicing regulator, and mutation in this sequence results in exon 11 skipping. Furthermore, RbFox2 knockdown in H4IIE cells enhanced exon 11 skipping of endogenous IR pre-mRNA. Lastly mutations in the SRSF3 binding site of exon11 together with the Rbfox2 binding site completely abolished exon 11 inclusion with a mini-gene reporter pre-mRNA. Our results indicate that RbFox2 and SRSF3 proteins mediate exon 11 inclusion in rat hepatoma cells.
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Affiliation(s)
- Takahito Nakura
- Laboratory of Cell Regulation, Departments of Animal Sciences and Applied Biological Chemistry, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Atsufumi Ozoe
- Laboratory of Cell Regulation, Departments of Animal Sciences and Applied Biological Chemistry, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Yuka Narita
- Laboratory of Cell Regulation, Departments of Animal Sciences and Applied Biological Chemistry, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Masafumi Matsuo
- KNC Department of Nucleic Acid Drug Discovery, Faculty of Rehabilitation, Kobe Gakuin University, Kobe, Japan
| | - Fumihiko Hakuno
- Laboratory of Cell Regulation, Departments of Animal Sciences and Applied Biological Chemistry, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Naoyuki Kataoka
- Laboratory of Cell Regulation, Departments of Animal Sciences and Applied Biological Chemistry, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Tokyo, Japan; Laboratory of Cellular Biochemistry, Department of Animal Resource Sciences, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Japan.
| | - Shin-Ichiro Takahashi
- Laboratory of Cell Regulation, Departments of Animal Sciences and Applied Biological Chemistry, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Tokyo, Japan.
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12
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Chen X, Liu Y, Xu C, Ba L, Liu Z, Li X, Huang J, Simpson E, Gao H, Cao D, Sheng W, Qi H, Ji H, Sanderson M, Cai CL, Li X, Yang L, Na J, Yamamura K, Liu Y, Huang G, Shou W, Sun N. QKI is a critical pre-mRNA alternative splicing regulator of cardiac myofibrillogenesis and contractile function. Nat Commun 2021; 12:89. [PMID: 33397958 PMCID: PMC7782589 DOI: 10.1038/s41467-020-20327-5] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2019] [Accepted: 11/27/2020] [Indexed: 01/29/2023] Open
Abstract
The RNA-binding protein QKI belongs to the hnRNP K-homology domain protein family, a well-known regulator of pre-mRNA alternative splicing and is associated with several neurodevelopmental disorders. Qki is found highly expressed in developing and adult hearts. By employing the human embryonic stem cell (hESC) to cardiomyocyte differentiation system and generating QKI-deficient hESCs (hESCs-QKIdel) using CRISPR/Cas9 gene editing technology, we analyze the physiological role of QKI in cardiomyocyte differentiation, maturation, and contractile function. hESCs-QKIdel largely maintain normal pluripotency and normal differentiation potential for the generation of early cardiogenic progenitors, but they fail to transition into functional cardiomyocytes. In this work, by using a series of transcriptomic, cell and biochemical analyses, and the Qki-deficient mouse model, we demonstrate that QKI is indispensable to cardiac sarcomerogenesis and cardiac function through its regulation of alternative splicing in genes involved in Z-disc formation and contractile physiology, suggesting that QKI is associated with the pathogenesis of certain forms of cardiomyopathies.
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Affiliation(s)
- Xinyun Chen
- grid.8547.e0000 0001 0125 2443Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Fudan University, Shanghai, China ,grid.411333.70000 0004 0407 2968Shanghai Key Laboratory of Birth Defects, Children’s Hospital of Fudan University, Shanghai, China ,grid.257413.60000 0001 2287 3919Herman B Wells Center for Pediatric Research, Department of Pediatrics, Indiana University School of Medicine, Indianapolis, IN USA
| | - Ying Liu
- grid.257413.60000 0001 2287 3919Herman B Wells Center for Pediatric Research, Department of Pediatrics, Indiana University School of Medicine, Indianapolis, IN USA
| | - Chen Xu
- grid.8547.e0000 0001 0125 2443Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Fudan University, Shanghai, China ,grid.257413.60000 0001 2287 3919Herman B Wells Center for Pediatric Research, Department of Pediatrics, Indiana University School of Medicine, Indianapolis, IN USA
| | - Lina Ba
- grid.257413.60000 0001 2287 3919Herman B Wells Center for Pediatric Research, Department of Pediatrics, Indiana University School of Medicine, Indianapolis, IN USA
| | - Zhuo Liu
- grid.257413.60000 0001 2287 3919Herman B Wells Center for Pediatric Research, Department of Pediatrics, Indiana University School of Medicine, Indianapolis, IN USA
| | - Xiuya Li
- grid.8547.e0000 0001 0125 2443Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Fudan University, Shanghai, China
| | - Jie Huang
- grid.8547.e0000 0001 0125 2443Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Fudan University, Shanghai, China
| | - Ed Simpson
- grid.257413.60000 0001 2287 3919Department of Bioinformatics, Indiana University School of Medicine, Indianapolis, IN USA
| | - Hongyu Gao
- grid.257413.60000 0001 2287 3919Department of Bioinformatics, Indiana University School of Medicine, Indianapolis, IN USA
| | - Dayan Cao
- Institute of Materia Medica and Center of Translational Medicine, College of Pharmacy, Army Medical University, Chongqing, China
| | - Wei Sheng
- grid.411333.70000 0004 0407 2968Shanghai Key Laboratory of Birth Defects, Children’s Hospital of Fudan University, Shanghai, China ,grid.257413.60000 0001 2287 3919Herman B Wells Center for Pediatric Research, Department of Pediatrics, Indiana University School of Medicine, Indianapolis, IN USA
| | - Hanping Qi
- grid.257413.60000 0001 2287 3919Herman B Wells Center for Pediatric Research, Department of Pediatrics, Indiana University School of Medicine, Indianapolis, IN USA
| | - Hongrui Ji
- grid.257413.60000 0001 2287 3919Herman B Wells Center for Pediatric Research, Department of Pediatrics, Indiana University School of Medicine, Indianapolis, IN USA
| | - Maria Sanderson
- grid.257413.60000 0001 2287 3919Herman B Wells Center for Pediatric Research, Department of Pediatrics, Indiana University School of Medicine, Indianapolis, IN USA
| | - Chen-Leng Cai
- grid.257413.60000 0001 2287 3919Herman B Wells Center for Pediatric Research, Department of Pediatrics, Indiana University School of Medicine, Indianapolis, IN USA
| | - Xiaohui Li
- Institute of Materia Medica and Center of Translational Medicine, College of Pharmacy, Army Medical University, Chongqing, China
| | - Lei Yang
- grid.257413.60000 0001 2287 3919Herman B Wells Center for Pediatric Research, Department of Pediatrics, Indiana University School of Medicine, Indianapolis, IN USA
| | - Jie Na
- grid.12527.330000 0001 0662 3178Center for Stem Cell Biology and Regenerative Medicine, School of Medicine, Tsinghua University, Beijing, China
| | - Kenichi Yamamura
- Institute of Resource Development and Analysis, Kumanoto University, Kumanoto, Japan
| | - Yunlong Liu
- grid.257413.60000 0001 2287 3919Department of Bioinformatics, Indiana University School of Medicine, Indianapolis, IN USA
| | - Guoying Huang
- grid.411333.70000 0004 0407 2968Shanghai Key Laboratory of Birth Defects, Children’s Hospital of Fudan University, Shanghai, China
| | - Weinian Shou
- grid.257413.60000 0001 2287 3919Herman B Wells Center for Pediatric Research, Department of Pediatrics, Indiana University School of Medicine, Indianapolis, IN USA
| | - Ning Sun
- grid.8547.e0000 0001 0125 2443Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Fudan University, Shanghai, China ,grid.411333.70000 0004 0407 2968Shanghai Key Laboratory of Birth Defects, Children’s Hospital of Fudan University, Shanghai, China
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13
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Palazzo AF, Kang YM. GC-content biases in protein-coding genes act as an "mRNA identity" feature for nuclear export. Bioessays 2020; 43:e2000197. [PMID: 33165929 DOI: 10.1002/bies.202000197] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 09/30/2020] [Accepted: 10/01/2020] [Indexed: 01/11/2023]
Abstract
It has long been observed that human protein-coding genes have a particular distribution of GC-content: the 5' end of these genes has high GC-content while the 3' end has low GC-content. In 2012, it was proposed that this pattern of GC-content could act as an mRNA identity feature that would lead to it being better recognized by the cellular machinery to promote its nuclear export. In contrast, junk RNA, which largely lacks this feature, would be retained in the nucleus and targeted for decay. Now two recent papers have provided evidence that GC-content does promote the nuclear export of many mRNAs in human cells.
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Affiliation(s)
- Alexander F Palazzo
- Department of Biochemistry, University of Toronto, Toronto, ON, M5G 1M1, Canada
| | - Yoon Mo Kang
- Department of Biochemistry, University of Toronto, Toronto, ON, M5G 1M1, Canada
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14
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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: 5.5] [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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15
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Mora Gallardo C, Sánchez de Diego A, Gutiérrez Hernández J, Talavera-Gutiérrez A, Fischer T, Martínez-A C, van Wely KHM. Dido3-dependent SFPQ recruitment maintains efficiency in mammalian alternative splicing. Nucleic Acids Res 2019; 47:5381-5394. [PMID: 30931476 PMCID: PMC6547428 DOI: 10.1093/nar/gkz235] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Revised: 03/19/2019] [Accepted: 03/22/2019] [Indexed: 12/12/2022] Open
Abstract
Alternative splicing is facilitated by accessory proteins that guide spliceosome subunits to the primary transcript. Many of these splicing factors recognize the RNA polymerase II tail, but SFPQ is a notable exception even though essential for mammalian RNA processing. This study reveals a novel role for Dido3, one of three Dido gene products, in alternative splicing. Binding of the Dido3 amino terminus to histones and to the polymerase jaw domain was previously reported, and here we show interaction between its carboxy terminus and SFPQ. We generated a mutant that eliminates Dido3 but preserves other Dido gene products, mimicking reduced Dido3 levels in myeloid neoplasms. Dido mutation suppressed SFPQ binding to RNA and increased skipping for a large group of exons. Exons bearing recognition sequences for alternative splicing factors were nonetheless included more efficiently. Reduced SFPQ recruitment may thus account for increased skipping of SFPQ-dependent exons, but could also generate a splicing factor surplus that becomes available to competing splice sites. Taken together, our data indicate that Dido3 is an adaptor that controls SFPQ utilization in RNA splicing. Distributing splicing factor recruitment over parallel pathways provides mammals with a simple mechanism to regulate exon usage while maintaining RNA splicing efficiency.
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Affiliation(s)
- Carmen Mora Gallardo
- Department of Immunology and Oncology, Centro Nacional de Biotecnología (CNB)/CSIC, Darwin 3, Campus UAM Cantoblanco, 28049 Madrid, Spain
| | - Ainhoa Sánchez de Diego
- Department of Immunology and Oncology, Centro Nacional de Biotecnología (CNB)/CSIC, Darwin 3, Campus UAM Cantoblanco, 28049 Madrid, Spain
| | - Julio Gutiérrez Hernández
- Department of Immunology and Oncology, Centro Nacional de Biotecnología (CNB)/CSIC, Darwin 3, Campus UAM Cantoblanco, 28049 Madrid, Spain
| | - Amaia Talavera-Gutiérrez
- Department of Immunology and Oncology, Centro Nacional de Biotecnología (CNB)/CSIC, Darwin 3, Campus UAM Cantoblanco, 28049 Madrid, Spain
| | - Thierry Fischer
- Department of Immunology and Oncology, Centro Nacional de Biotecnología (CNB)/CSIC, Darwin 3, Campus UAM Cantoblanco, 28049 Madrid, Spain
| | - Carlos Martínez-A
- Department of Immunology and Oncology, Centro Nacional de Biotecnología (CNB)/CSIC, Darwin 3, Campus UAM Cantoblanco, 28049 Madrid, Spain
| | - Karel H M van Wely
- Department of Immunology and Oncology, Centro Nacional de Biotecnología (CNB)/CSIC, Darwin 3, Campus UAM Cantoblanco, 28049 Madrid, Spain
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16
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Kim K, Nguyen TD, Li S, Nguyen TA. SRSF3 recruits DROSHA to the basal junction of primary microRNAs. RNA (NEW YORK, N.Y.) 2018; 24:892-898. [PMID: 29615481 PMCID: PMC6004053 DOI: 10.1261/rna.065862.118] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2018] [Accepted: 03/29/2018] [Indexed: 05/22/2023]
Abstract
The Microprocessor complex, consisting of an RNase III DROSHA and the DGCR8 dimer, cleaves primary microRNA transcripts (pri-miRNAs) to initiate microRNA (miRNA) maturation. Pri-miRNAs are stem-loop RNAs, and ∼79% of them contain at least one of the three major and conserved RNA motifs, UG, UGU, and CNNC. We recently demonstrated that the basal UG and apical UGU motifs of pri-miRNAs interact with DROSHA and DGCR8, respectively. They help orient Microprocessor on pri-miRNA in a proper direction in which DROSHA and DGCR8 localize to the basal and apical pri-miRNA junctions, respectively. In addition, CNNC, located at ∼17 nucleotides (nt) from the Microprocessor cleavage site, interacts with SRSF3 (SRp20) to stimulate Microprocessor to process pri-miRNAs. The mechanism underlying this stimulation, however, is unknown. In this study, we discovered that SRSF3 recruits DROSHA to the basal junction in a CNNC-dependent manner, thereby enhancing Microprocessor activity. Furthermore, by generating various pri-miRNA substrates containing CNNC at different locations, we demonstrated that such stimulation only occurs when CNNC is located at ∼17 nt from the Microprocessor cleavage site. Our findings reveal the molecular mechanism of SRSF3 in pri-miRNA processing and support the previously proposed explanation for the highly conserved position of CNNC in SRSF3-enhanced pri-miRNA processing.
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Affiliation(s)
- Kijun Kim
- Center for RNA Research, Institute for Basic Science, Seoul 08826, Korea
- School of Biological Sciences, Seoul National University, Seoul 08826, Korea
| | - Trung Duc Nguyen
- Division of Life Science, Hong Kong University of Science and Technology, Hong Kong, China
- HKUST Shenzhen Research Institute, Shenzhen 518057, China
| | - Shaohua Li
- Division of Life Science, Hong Kong University of Science and Technology, Hong Kong, China
| | - Tuan Anh Nguyen
- Division of Life Science, Hong Kong University of Science and Technology, Hong Kong, China
- HKUST Shenzhen Research Institute, Shenzhen 518057, China
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17
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Albaqami M, Reddy ASN. Development of an in vitro pre-mRNA splicing assay using plant nuclear extract. PLANT METHODS 2018; 14:1. [PMID: 29321806 PMCID: PMC5757305 DOI: 10.1186/s13007-017-0271-6] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Accepted: 12/21/2017] [Indexed: 05/21/2023]
Abstract
BACKGROUND Pre-mRNA splicing is an essential post-transcriptional process in all eukaryotes. In vitro splicing systems using nuclear or cytoplasmic extracts from mammalian cells, yeast, and Drosophila have provided a wealth of mechanistic insights into assembly and composition of the spliceosome, splicing regulatory proteins and mechanisms of pre-mRNA splicing in non-plant systems. The lack of an in vitro splicing system prepared from plant cells has been a major limitation in splicing research in plants. RESULTS Here we report an in vitro splicing assay system using plant nuclear extract. Several lines of evidence indicate that nuclear extract derived from Arabidopsis seedlings can convert pre-mRNA substrate (LHCB3) into a spliced product. These include: (1) generation of an RNA product that corresponds to the size of expected mRNA, (2) a junction-mapping assay using S1 nuclease revealed that the two exons are spliced together, (3) the reaction conditions are similar to those found with non-plant extracts and (4) finally mutations in conserved donor and acceptor sites abolished the production of the spliced product. CONCLUSIONS This first report on the plant in vitro splicing assay opens new avenues to investigate plant spliceosome assembly and composition, and splicing regulatory mechanisms specific to plants.
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Affiliation(s)
- Mohammed Albaqami
- Department of Biology and Program in Cell and Molecular Biology, Colorado State University, Fort Collins, CO 80523-1878 USA
| | - Anireddy S. N. Reddy
- Department of Biology and Program in Cell and Molecular Biology, Colorado State University, Fort Collins, CO 80523-1878 USA
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18
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Ramanouskaya TV, Grinev VV. The determinants of alternative RNA splicing in human cells. Mol Genet Genomics 2017; 292:1175-1195. [PMID: 28707092 DOI: 10.1007/s00438-017-1350-0] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Accepted: 07/06/2017] [Indexed: 12/29/2022]
Abstract
Alternative splicing represents an important level of the regulation of gene function in eukaryotic organisms. It plays a critical role in virtually every biological process within an organism, including regulation of cell division and cell death, differentiation of tissues in the embryo and the adult organism, as well as in cellular response to diverse environmental factors. In turn, studies of the last decade have shown that alternative splicing itself is controlled by different mechanisms. Unfortunately, there is no clear understanding of how these diverse mechanisms, or determinants, regulate and constrain the set of alternative RNA species produced from any particular gene in every cell of the human body. Here, we provide a consolidated overview of alternative splicing determinants including RNA-protein interactions, epigenetic regulation via chromatin remodeling, coupling of transcription-to-alternative splicing, effect of secondary structures in pre-RNA, and function of the RNA quality control systems. We also extensively and critically discuss some mechanistic insights on coordinated inclusion/exclusion of exons during the formation of mature RNA molecules. We conclude that the final structure of RNA is pre-determined by a complex interplay between cis- and trans-acting factors. Altogether, currently available empirical data significantly expand our understanding of the functioning of the alternative splicing machinery of cells in normal and pathological conditions. On the other hand, there are still many blind spots that require further deep investigations.
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19
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Wu W, Zong J, Wei N, Cheng J, Zhou X, Cheng Y, Chen D, Guo Q, Zhang B, Feng Y. CASH: a constructing comprehensive splice site method for detecting alternative splicing events. Brief Bioinform 2017; 19:905-917. [DOI: 10.1093/bib/bbx034] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Indexed: 01/03/2023] Open
Affiliation(s)
- Wenwu Wu
- The State Key Laboratory of Subtropical Silviculture, Zhejiang A & F University, Lin’an, Hangzhou, China
| | - Jie Zong
- Novel Bioinformatics Co., Ltd, Shanghai, China
| | - Ning Wei
- Institute for Nutritional Sciences, Chinese Academy of Sciences (CAS), Shanghai, China
| | - Jian Cheng
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences (CAS), Shanghai, China
| | - Xuexia Zhou
- Tianjin Medical University General Hospital, China
| | - Yuanming Cheng
- Institute for Nutritional Sciences, Chinese Academy of Sciences (CAS), Shanghai, China
| | - Dai Chen
- Novel Bioinformatics Co., Ltd, Shanghai, China
| | - Qinghua Guo
- Novel Bioinformatics Co., Ltd, Shanghai, China
| | - Bo Zhang
- Novel Bioinformatics Co., Ltd, Shanghai, China
| | - Ying Feng
- Institute for Nutritional Sciences, Chinese Academy of Sciences (CAS), Shanghai, China
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20
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Abstract
Serine and arginine-rich (SR) proteins are RNA-binding proteins (RBPs) known as constitutive and alternative splicing regulators. As splicing is linked to transcriptional and post-transcriptional steps, SR proteins are implicated in the regulation of multiple aspects of the gene expression program. Recent global analyses of SR-RNA interaction maps have advanced our understanding of SR-regulated gene expression. Diverse SR proteins play partially overlapping but distinct roles in transcription-coupled splicing and mRNA processing in the nucleus. In addition, shuttling SR proteins act as adaptors for mRNA export and as regulators for translation in the cytoplasm. This mini-review will summarize the roles of SR proteins as RNA binders, regulators, and connectors from transcription in the nucleus to translation in the cytoplasm.
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Affiliation(s)
- Sunjoo Jeong
- Department of Bioconvergent Science and Technology, Dankook University, Yongin 16890,
Korea
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21
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Skrdlant L, Lin RJ. Characterization of RNA-Protein Interactions: Lessons from Two RNA-Binding Proteins, SRSF1 and SRSF2. Methods Mol Biol 2016; 1421:1-13. [PMID: 26965252 DOI: 10.1007/978-1-4939-3591-8_1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
SR proteins are a class of RNA-binding proteins whose RNA-binding ability is required for both constitutive and alternative splicing. While members of the SR protein family were once thought to have redundant functions, in-depth biochemical analysis of their RNA-binding abilities has revealed distinct binding profiles for each SR protein, that often lead to either synergistic or antagonistic functions. SR protein family members SRSF1 and SRSF2 are two of the most highly studied RNA-binding proteins. Here we examine the various methods used to differentiate SRSF1 and SRSF2 RNA-binding ability. We discuss the benefits and type of information that can be determined using each method.
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Affiliation(s)
- Lindsey Skrdlant
- Irell & Manella Graduate School of Biological Sciences of the City of Hope, Duarte, CA, USA
- Department of Molecular and Cellular Biology, Beckman Research Institute of the City of Hope, 1500 E. Duarte Road, Duarte, CA, 91010, USA
| | - Ren-Jang Lin
- Irell & Manella Graduate School of Biological Sciences of the City of Hope, Duarte, CA, USA.
- Department of Molecular and Cellular Biology, Beckman Research Institute of the City of Hope, 1500 E. Duarte Road, Duarte, CA, 91010, USA.
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22
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Anczuków O, Akerman M, Cléry A, Wu J, Shen C, Shirole NH, Raimer A, Sun S, Jensen MA, Hua Y, Allain FHT, Krainer AR. SRSF1-Regulated Alternative Splicing in Breast Cancer. Mol Cell 2015; 60:105-17. [PMID: 26431027 PMCID: PMC4597910 DOI: 10.1016/j.molcel.2015.09.005] [Citation(s) in RCA: 236] [Impact Index Per Article: 26.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Revised: 07/24/2015] [Accepted: 08/28/2015] [Indexed: 12/28/2022]
Abstract
Splicing factor SRSF1 is upregulated in human breast tumors, and its overexpression promotes transformation of mammary cells. Using RNA-seq, we identified SRSF1-regulated alternative splicing (AS) targets in organotypic three-dimensional MCF-10A cell cultures that mimic a context relevant to breast cancer. We identified and validated hundreds of endogenous SRSF1-regulated AS events. De novo discovery of the SRSF1 binding motif reconciled discrepancies in previous motif analyses. Using a Bayesian model, we determined positional effects of SRSF1 binding on cassette exons: binding close to the 5' splice site generally promoted exon inclusion, whereas binding near the 3' splice site promoted either exon skipping or inclusion. Finally, we identified SRSF1-regulated AS events deregulated in human tumors; overexpressing one such isoform, exon-9-included CASC4, increased acinar size and proliferation, and decreased apoptosis, partially recapitulating SRSF1's oncogenic effects. Thus, we uncovered SRSF1 positive and negative regulatory mechanisms, and oncogenic AS events that represent potential targets for therapeutics development.
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Affiliation(s)
- Olga Anczuków
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA
| | - Martin Akerman
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA
| | - Antoine Cléry
- Institute for Molecular Biology and Biophysics, Department of Biology, ETH Zurich, 8093 Zurich, Switzerland
| | - Jie Wu
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA; Department of Applied Mathematics and Statistics, Stony Brook University, Stony Brook, NY 11794, USA
| | - Chen Shen
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA; Molecular and Cellular Biology Program, Stony Brook University, Stony Brook, NY 11794, USA
| | - Nitin H Shirole
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA; Graduate Program in Genetics, Stony Brook University, Stony Brook, NY 11794, USA
| | - Amanda Raimer
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA
| | - Shuying Sun
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA
| | - Mads A Jensen
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA
| | - Yimin Hua
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA
| | - Frédéric H-T Allain
- Institute for Molecular Biology and Biophysics, Department of Biology, ETH Zurich, 8093 Zurich, Switzerland
| | - Adrian R Krainer
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA.
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23
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Disease-associated mutation in SRSF2 misregulates splicing by altering RNA-binding affinities. Proc Natl Acad Sci U S A 2015; 112:E4726-34. [PMID: 26261309 DOI: 10.1073/pnas.1514105112] [Citation(s) in RCA: 157] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Serine/arginine-rich splicing factor 2 (SRSF2) is an RNA-binding protein that plays important roles in splicing of mRNA precursors. SRSF2 mutations are frequently found in patients with myelodysplastic syndromes and certain leukemias, but how these mutations affect SRSF2 function has only begun to be examined. We used clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein-9 nuclease to introduce the P95H mutation to SRSF2 in K562 leukemia cells, generating an isogenic model so that splicing alterations can be attributed solely to mutant SRSF2. We found that SRSF2 (P95H) misregulates 548 splicing events (<1% of total). Of these events, 374 involved the inclusion of cassette exons, and the inclusion was either increased (206) or decreased (168). We detected a specific motif (UCCA/UG) enriched in the more-included exons and a distinct motif (UGGA/UG) in the more-excluded exons. RNA gel shift assays showed that a mutant SRSF2 derivative bound more tightly than its wild-type counterpart to RNA sites containing UCCAG but bound less tightly to UGGAG sites. Thus in most cases the pattern of exon inclusion or exclusion correlated with stronger or weaker RNA binding, respectively. We further show that the P95H mutation does not affect other functions of SRSF2, i.e., protein-protein interactions with key splicing factors. Our results thus demonstrate that the P95H mutation positively or negatively alters the binding affinity of SRSF2 for cognate RNA sites in target transcripts, leading to misregulation of exon inclusion. Our findings shed light on the mechanism of the disease-associated SRSF2 mutation in splicing regulation and also reveal a group of misspliced mRNA isoforms for potential therapeutic targeting.
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Sestili F, Palombieri S, Botticella E, Mantovani P, Bovina R, Lafiandra D. TILLING mutants of durum wheat result in a high amylose phenotype and provide information on alternative splicing mechanisms. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2015; 233:127-133. [PMID: 25711820 DOI: 10.1016/j.plantsci.2015.01.009] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Revised: 01/15/2015] [Accepted: 01/18/2015] [Indexed: 05/20/2023]
Abstract
The amylose/amylopectin ratio has a major influence over the properties of starch and determines its optimal end use. Here, high amylose durum wheat has been bred by combining knock down alleles at the two homoelogous genes encoding starch branching enzyme IIa (SBEIIa-A and SBEIIa-B). The complete silencing of these genes had a number of pleiotropic effects on starch synthesis: it affected the transcriptional activity of SBEIIb, ISA1 (starch debranching enzyme) and all of the genes encoding starch synthases (SSI, SSIIa, SSIII and GBSSI). The starch produced by grain of the double SBEIIa mutants was high in amylose (up to ∼1.95 fold that of the wild type) and contained up to about eight fold more resistant starch. A single nucleotide polymorphism adjacent to the splice site at the end of exon 10 of the G364E mutant copies of both SBEIIa-A and SBEIIa-B resulted in the loss of a conserved exonic splicing silencer element. Its starch was similar to that of the SBEIIa double mutant. G364E SBEIIa pre-mRNA was incorrectly processed, resulting in the formation of alternative, but non-functional splicing products.
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Affiliation(s)
- Francesco Sestili
- Department of Agriculture, Forestry, Nature & Energy, University of Tuscia, Via S Camillo de Lellis SNC, 01100 Viterbo, Italy.
| | - Samuela Palombieri
- Department of Agriculture, Forestry, Nature & Energy, University of Tuscia, Via S Camillo de Lellis SNC, 01100 Viterbo, Italy.
| | - Ermelinda Botticella
- Department of Agriculture, Forestry, Nature & Energy, University of Tuscia, Via S Camillo de Lellis SNC, 01100 Viterbo, Italy.
| | - Paola Mantovani
- Società Produttori Sementi Spa, Via Macero 1, 40050 Argelato, Bologna, Italy.
| | - Riccardo Bovina
- Società Produttori Sementi Spa, Via Macero 1, 40050 Argelato, Bologna, Italy; Department of Agricultural Science (DipSA), University of Bologna, Viale Fanin 44, 40127 Bologna, Italy.
| | - Domenico Lafiandra
- Department of Agriculture, Forestry, Nature & Energy, University of Tuscia, Via S Camillo de Lellis SNC, 01100 Viterbo, Italy.
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Decoding mechanisms by which silent codon changes influence protein biogenesis and function. Int J Biochem Cell Biol 2015; 64:58-74. [PMID: 25817479 DOI: 10.1016/j.biocel.2015.03.011] [Citation(s) in RCA: 90] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Revised: 03/02/2015] [Accepted: 03/14/2015] [Indexed: 02/07/2023]
Abstract
SCOPE Synonymous codon usage has been a focus of investigation since the discovery of the genetic code and its redundancy. The occurrences of synonymous codons vary between species and within genes of the same genome, known as codon usage bias. Today, bioinformatics and experimental data allow us to compose a global view of the mechanisms by which the redundancy of the genetic code contributes to the complexity of biological systems from affecting survival in prokaryotes, to fine tuning the structure and function of proteins in higher eukaryotes. Studies analyzing the consequences of synonymous codon changes in different organisms have revealed that they impact nucleic acid stability, protein levels, structure and function without altering amino acid sequence. As such, synonymous mutations inevitably contribute to the pathogenesis of complex human diseases. Yet, fundamental questions remain unresolved regarding the impact of silent mutations in human disorders. In the present review we describe developments in this area concentrating on mechanisms by which synonymous mutations may affect protein function and human health. PURPOSE This synopsis illustrates the significance of synonymous mutations in disease pathogenesis. We review the different steps of gene expression affected by silent mutations, and assess the benefits and possible harmful effects of codon optimization applied in the development of therapeutic biologics. PHYSIOLOGICAL AND MEDICAL RELEVANCE Understanding mechanisms by which synonymous mutations contribute to complex diseases such as cancer, neurodegeneration and genetic disorders, including the limitations of codon-optimized biologics, provides insight concerning interpretation of silent variants and future molecular therapies.
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Abstract
Precursor messenger RNA (pre-mRNA) splicing is a critical step in the posttranscriptional regulation of gene expression, providing significant expansion of the functional proteome of eukaryotic organisms with limited gene numbers. Split eukaryotic genes contain intervening sequences or introns disrupting protein-coding exons, and intron removal occurs by repeated assembly of a large and highly dynamic ribonucleoprotein complex termed the spliceosome, which is composed of five small nuclear ribonucleoprotein particles, U1, U2, U4/U6, and U5. Biochemical studies over the past 10 years have allowed the isolation as well as compositional, functional, and structural analysis of splicing complexes at distinct stages along the spliceosome cycle. The average human gene contains eight exons and seven introns, producing an average of three or more alternatively spliced mRNA isoforms. Recent high-throughput sequencing studies indicate that 100% of human genes produce at least two alternative mRNA isoforms. Mechanisms of alternative splicing include RNA-protein interactions of splicing factors with regulatory sites termed silencers or enhancers, RNA-RNA base-pairing interactions, or chromatin-based effects that can change or determine splicing patterns. Disease-causing mutations can often occur in splice sites near intron borders or in exonic or intronic RNA regulatory silencer or enhancer elements, as well as in genes that encode splicing factors. Together, these studies provide mechanistic insights into how spliceosome assembly, dynamics, and catalysis occur; how alternative splicing is regulated and evolves; and how splicing can be disrupted by cis- and trans-acting mutations leading to disease states. These findings make the spliceosome an attractive new target for small-molecule, antisense, and genome-editing therapeutic interventions.
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Affiliation(s)
- Yeon Lee
- Center for RNA Systems Biology; Division of Biochemistry, Biophysics, and Structural Biology; Department of Molecular and Cell Biology, University of California, Berkeley, California 94720-3204;
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Abstract
RRM-containing proteins are involved in most of the RNA metabolism steps. Their functions are closely related to their mode of RNA recognition, which has been studied by structural biologists for more than 20 years. In this chapter, we report on high-resolution structures of single and multi RRM-RNA complexes to explain the numerous strategies used by these domains to interact specifically with a large repertoire of RNA sequences. We show that multiple variations of their canonical fold can be used to adapt to different single-stranded sequences with a large range of affinities. Furthermore, we describe the consequences on RNA binding of the different structural arrangements found in tandem RRMs and higher order RNPs. Importantly, these structures also reveal with very high accuracy the RNA motifs bound specifically by RRM-containing proteins, which correspond very often to consensus sequences identified with genome-wide approaches. Finally, we show how structural and cellular biology can benefit from each other and pave a way for understanding, defining, and predicting a code of RNA recognition by the RRMs.
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Lee Y, Rio DC. Mechanisms and Regulation of Alternative Pre-mRNA Splicing. Annu Rev Biochem 2015. [PMID: 25784052 DOI: 10.1146/annurev-biochem-060614-034316.mechanisms] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Precursor messenger RNA (pre-mRNA) splicing is a critical step in the posttranscriptional regulation of gene expression, providing significant expansion of the functional proteome of eukaryotic organisms with limited gene numbers. Split eukaryotic genes contain intervening sequences or introns disrupting protein-coding exons, and intron removal occurs by repeated assembly of a large and highly dynamic ribonucleoprotein complex termed the spliceosome, which is composed of five small nuclear ribonucleoprotein particles, U1, U2, U4/U6, and U5. Biochemical studies over the past 10 years have allowed the isolation as well as compositional, functional, and structural analysis of splicing complexes at distinct stages along the spliceosome cycle. The average human gene contains eight exons and seven introns, producing an average of three or more alternatively spliced mRNA isoforms. Recent high-throughput sequencing studies indicate that 100% of human genes produce at least two alternative mRNA isoforms. Mechanisms of alternative splicing include RNA-protein interactions of splicing factors with regulatory sites termed silencers or enhancers, RNA-RNA base-pairing interactions, or chromatin-based effects that can change or determine splicing patterns. Disease-causing mutations can often occur in splice sites near intron borders or in exonic or intronic RNA regulatory silencer or enhancer elements, as well as in genes that encode splicing factors. Together, these studies provide mechanistic insights into how spliceosome assembly, dynamics, and catalysis occur; how alternative splicing is regulated and evolves; and how splicing can be disrupted by cis- and trans-acting mutations leading to disease states. These findings make the spliceosome an attractive new target for small-molecule, antisense, and genome-editing therapeutic interventions.
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Affiliation(s)
- Yeon Lee
- Center for RNA Systems Biology; Division of Biochemistry, Biophysics, and Structural Biology; Department of Molecular and Cell Biology, University of California, Berkeley, California 94720-3204;
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Guyot M, Pagès G. VEGF Splicing and the Role of VEGF Splice Variants: From Physiological-Pathological Conditions to Specific Pre-mRNA Splicing. Methods Mol Biol 2015; 1332:3-23. [PMID: 26285742 DOI: 10.1007/978-1-4939-2917-7_1] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
During this past decade, the vascular endothelial growth factor (VEGF) pathway has been extensively studied. VEGF is a paradigm of molecular regulation since its expression is controlled at all possible steps including transcription, mRNA stability, translation, and pre-mRNA splicing. The latter form of molecular regulation is probably the least studied. This field has been neglected; yet different forms of VEGF with different sizes and different physiological properties issued from alternative splicing have been described a long time ago. Recently a new level of complexity was added to the field of splicing of VEGF pre-mRNA. Whereas thousands of publications have described VEGF as a pro-angiogenic factor, an alternative splicing event generates specific anti-angiogenic forms of VEGF that only differ from the others by a modification in the last six amino acids of the protein. According to the scientists who discovered these isoforms, which are indistinguishable from the pro-angiogenic ones with pan VEGF antibodies, some of the literature on VEGF is at least inexact if not completely false. Moreover, the presence of anti-angiogenic forms of VEGF may explain the disappointing efficacy of anti-VEGF therapies on the overall survival of patients with different forms of cancers and with wet age-related macular degeneration. This review focuses on the existence of the different alternative splice variants of VEGF and the molecular mechanisms associated with their expression and function.
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Affiliation(s)
- Mélanie Guyot
- Institute for Research on Cancer and Aging of Nice (IRCAN), University of Nice Sophia Antipolis, Centre Antoine Lacassagne 33 Avenue de Valombrose, UMR CNRS 7284/INSERM U 1081, Nice, 06189, France
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Wee CD, Havens MA, Jodelka FM, Hastings ML. Targeting SR proteins improves SMN expression in spinal muscular atrophy cells. PLoS One 2014; 9:e115205. [PMID: 25506695 PMCID: PMC4266657 DOI: 10.1371/journal.pone.0115205] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2014] [Accepted: 11/19/2014] [Indexed: 12/19/2022] Open
Abstract
Spinal muscular atrophy (SMA) is one of the most common inherited causes of pediatric mortality. SMA is caused by deletions or mutations in the survival of motor neuron 1 (SMN1) gene, which results in SMN protein deficiency. Humans have a centromeric copy of the survival of motor neuron gene, SMN2, which is nearly identical to SMN1. However, SMN2 cannot compensate for the loss of SMN1 because SMN2 has a single-nucleotide difference in exon 7, which negatively affects splicing of the exon. As a result, most mRNA produced from SMN2 lacks exon 7. SMN2 mRNA lacking exon 7 encodes a truncated protein with reduced functionality. Improving SMN2 exon 7 inclusion is a goal of many SMA therapeutic strategies. The identification of regulators of exon 7 inclusion may provide additional therapeutic targets or improve the design of existing strategies. Although a number of regulators of exon 7 inclusion have been identified, the function of most splicing proteins in exon 7 inclusion is unknown. Here, we test the role of SR proteins and hnRNP proteins in SMN2 exon 7 inclusion. Knockdown and overexpression studies reveal that SRSF1, SRSF2, SRSF3, SRSF4, SRSF5, SRSF6, SRSF7, SRSF11, hnRNPA1/B1 and hnRNP U can inhibit exon 7 inclusion. Depletion of two of the most potent inhibitors of exon 7 inclusion, SRSF2 or SRSF3, in cell lines derived from SMA patients, increased SMN2 exon 7 inclusion and SMN protein. Our results identify novel regulators of SMN2 exon 7 inclusion, revealing potential targets for SMA therapeutics.
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Affiliation(s)
- Claribel D. Wee
- Department of Cell Biology and Anatomy, The Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, Illinois, United States of America
| | - Mallory A. Havens
- Department of Cell Biology and Anatomy, The Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, Illinois, United States of America
| | - Francine M. Jodelka
- Department of Cell Biology and Anatomy, The Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, Illinois, United States of America
| | - Michelle L. Hastings
- Department of Cell Biology and Anatomy, The Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, Illinois, United States of America
- * E-mail:
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31
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Regulation of gene expression programmes by serine–arginine rich splicing factors. Semin Cell Dev Biol 2014; 32:11-21. [DOI: 10.1016/j.semcdb.2014.03.011] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Accepted: 03/11/2014] [Indexed: 12/21/2022]
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32
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Poliakov E, Koonin EV, Rogozin IB. Impairment of translation in neurons as a putative causative factor for autism. Biol Direct 2014; 9:16. [PMID: 25011470 PMCID: PMC4099083 DOI: 10.1186/1745-6150-9-16] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2014] [Accepted: 07/01/2014] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND A dramatic increase in the prevalence of autism and Autistic Spectrum Disorders (ASD) has been observed over the last two decades in USA, Europe and Asia. Given the accumulating data on the possible role of translation in the etiology of ASD, we analyzed potential effects of rare synonymous substitutions associated with ASD on mRNA stability, splicing enhancers and silencers, and codon usage. PRESENTATION OF THE HYPOTHESIS We hypothesize that subtle impairment of translation, resulting in dosage imbalance of neuron-specific proteins, contributes to the etiology of ASD synergistically with environmental neurotoxins. TESTING THE HYPOTHESIS A statistically significant shift from optimal to suboptimal codons caused by rare synonymous substitutions associated with ASD was detected whereas no effect on other analyzed characteristics of transcripts was identified. This result suggests that the impact of rare codons on the translation of genes involved in neuron development, even if slight in magnitude, could contribute to the pathogenesis of ASD in the presence of an aggressive chemical background. This hypothesis could be tested by further analysis of ASD-associated mutations, direct biochemical characterization of their effects, and assessment of in vivo effects on animal models. IMPLICATIONS OF THE HYPOTHESIS It seems likely that the synergistic action of environmental hazards with genetic variations that in themselves have limited or no deleterious effects but are potentiated by the environmental factors is a general principle that underlies the alarming increase in the ASD prevalence. REVIEWERS This article was reviewed by Andrey Rzhetsky, Neil R. Smalheiser, and Shamil R. Sunyaev.
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Affiliation(s)
- Eugenia Poliakov
- Laboratory of Retinal Cell & Molecular Biology, National Eye Institute, National Institutes of Health, Bethesda, MD, USA
| | - Eugene V Koonin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD, USA
| | - Igor B Rogozin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD, 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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34
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Cáceres EF, Hurst LD. The evolution, impact and properties of exonic splice enhancers. Genome Biol 2013; 14:R143. [PMID: 24359918 PMCID: PMC4054783 DOI: 10.1186/gb-2013-14-12-r143] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2013] [Accepted: 12/20/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND In humans, much of the information specifying splice sites is not at the splice site. Exonic splice enhancers are one of the principle non-splice site motifs. Four high-throughput studies have provided a compendium of motifs that function as exonic splice enhancers, but only one, RESCUE-ESE, has been generally employed to examine the properties of enhancers. Here we consider these four datasets to ask whether there is any consensus on the properties and impacts of exonic splice enhancers. RESULTS While only about 1% of all the identified hexamer motifs are common to all analyses we can define reasonably sized sets that are found in most datasets. These consensus intersection datasets we presume reflect the true properties of exonic splice enhancers. Given prior evidence for the properties of enhancers and splice-associated mutations, we ask for all datasets whether the exonic splice enhancers considered are purine enriched; enriched near exon boundaries; able to predict trends in relative codon usage; slow evolving at synonymous sites; rare in SNPs; associated with weak splice sites; and enriched near longer introns. While the intersect datasets match expectations, only one original dataset, RESCUE-ESE, does. Unexpectedly, a fully experimental dataset identifies motifs that commonly behave opposite to the consensus, for example, being enriched in exon cores where splice-associated mutations are rare. CONCLUSIONS Prior analyses that used the RESCUE-ESE set of hexamers captured the properties of consensus exonic splice enhancers. We estimate that at least 4% of synonymous mutations are deleterious owing to an effect on enhancer functioning.
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Gingras RM, Warren ME, Nagengast AA, Diangelo JR. The control of lipid metabolism by mRNA splicing in Drosophila. Biochem Biophys Res Commun 2013; 443:672-6. [PMID: 24333419 DOI: 10.1016/j.bbrc.2013.12.027] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2013] [Accepted: 12/04/2013] [Indexed: 10/25/2022]
Abstract
The storage of lipids is an evolutionarily conserved process that is important for the survival of organisms during shifts in nutrient availability. Triglycerides are stored in lipid droplets, but the mechanisms of how lipids are stored in these structures are poorly understood. Previous in vitro RNAi screens have implicated several components of the spliceosome in controlling lipid droplet formation and storage, but the in vivo relevance of these phenotypes is unclear. In this study, we identify specific members of the splicing machinery that are necessary for normal triglyceride storage in the Drosophila fat body. Decreasing the expression of the splicing factors U1-70K, U2AF38, U2AF50 in the fat body resulted in decreased triglyceride levels. Interestingly, while decreasing the SR protein 9G8 in the larval fat body yielded a similar triglyceride phenotype, its knockdown in the adult fat body resulted in a substantial increase in lipid stores. This increase in fat storage is due in part to altered splicing of the gene for the β-oxidation enzyme CPT1, producing an isoform with less enzymatic activity. Together, these data indicate a role for mRNA splicing in regulating lipid storage in Drosophila and provide a link between the regulation of gene expression and lipid homeostasis.
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Affiliation(s)
- Robert M Gingras
- Department of Biology, Hofstra University, Hempstead, NY 11549, United States
| | - Michelle E Warren
- Department of Biology, Hofstra University, Hempstead, NY 11549, United States
| | - Alexis A Nagengast
- Departments of Biochemistry and Chemistry, Widener University, Chester, PA 19103, United States.
| | - Justin R Diangelo
- Department of Biology, Hofstra University, Hempstead, NY 11549, United States; Hofstra University - North Shore/Long Island Jewish School of Medicine, Hempstead, NY 11549, United States.
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Jang HN, Lee M, Loh TJ, Choi SW, Oh HK, Moon H, Cho S, Hong SE, Kim DH, Sheng Z, Green MR, Park D, Zheng X, Shen H. Exon 9 skipping of apoptotic caspase-2 pre-mRNA is promoted by SRSF3 through interaction with exon 8. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2013; 1839:25-32. [PMID: 24321384 DOI: 10.1016/j.bbagrm.2013.11.006] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2013] [Revised: 11/14/2013] [Accepted: 11/26/2013] [Indexed: 01/24/2023]
Abstract
Alternative splicing plays an important role in gene expression by producing different proteins from a gene. Caspase-2 pre-mRNA produces anti-apoptotic Casp-2S and pro-apoptotic Casp-2L proteins through exon 9 inclusion or skipping. However, the molecular mechanisms of exon 9 splicing are not well understood. Here we show that knockdown of SRSF3 (also known as SRp20) with siRNA induced significant increase of endogenous exon 9 inclusion. In addition, overexpression of SRSF3 promoted exon 9 skipping. Thus we conclude that SRSF3 promotes exon 9 skipping. In order to understand the functional target of SRSF3 on caspase-2 pre-mRNA, we performed substitution and deletion mutagenesis on the potential SRSF3 binding sites that were predicted from previous reports. We demonstrate that substitution mutagenesis of the potential SRSF3 binding site on exon 8 severely disrupted the effects of SRSF3 on exon 9 skipping. Furthermore, with the approach of RNA pulldown and immunoblotting analysis we show that SRSF3 interacts with the potential SRSF3 binding RNA sequence on exon 8 but not with the mutant RNA sequence. In addition, we show that a deletion of 26nt RNA from 5' end of exon 8, a 33nt RNA from 3' end of exon 10 and a 2225nt RNA from intron 9 did not compromise the function of SRSF3 on exon 9 splicing. Therefore we conclude that SRSF3 promotes exon 9 skipping of caspase-2 pre-mRNA by interacting with exon 8. Our results reveal a novel mechanism of caspase-2 pre-mRNA splicing.
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Affiliation(s)
- Ha Na Jang
- School of life Sciences, Gwangju Institute of Science and Technology, Gwangju 500-712, Korea
| | - Minho Lee
- School of life Sciences, Gwangju Institute of Science and Technology, Gwangju 500-712, Korea
| | - Tiing Jen Loh
- School of life Sciences, Gwangju Institute of Science and Technology, Gwangju 500-712, Korea
| | - Seung-Woo Choi
- School of life Sciences, Gwangju Institute of Science and Technology, Gwangju 500-712, Korea
| | - Hyun Kyung Oh
- School of life Sciences, Gwangju Institute of Science and Technology, Gwangju 500-712, Korea
| | - Heegyum Moon
- School of life Sciences, Gwangju Institute of Science and Technology, Gwangju 500-712, Korea
| | - Sunghee Cho
- School of life Sciences, Gwangju Institute of Science and Technology, Gwangju 500-712, Korea
| | - Seong-Eui Hong
- School of life Sciences, Gwangju Institute of Science and Technology, Gwangju 500-712, Korea
| | - Do Han Kim
- School of life Sciences, Gwangju Institute of Science and Technology, Gwangju 500-712, Korea
| | - Zhi Sheng
- Virginia Tech Carilion Research Institute, Roanoke, VA, 24016, USA; Department of Biomedical Sciences and Pathobiology, Virginia-Maryland Regional College of Veterinary Medicine, Virginia Tech, Blacksburg, VA, 24061, USA
| | - Michael R Green
- Howard Hughes Medical Institute and Programs in Gene Function and Expression and Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
| | - Daeho Park
- School of life Sciences, Gwangju Institute of Science and Technology, Gwangju 500-712, Korea
| | - Xuexiu Zheng
- School of life Sciences, Gwangju Institute of Science and Technology, Gwangju 500-712, Korea
| | - Haihong Shen
- School of life Sciences, Gwangju Institute of Science and Technology, Gwangju 500-712, Korea
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Auyeung VC, Ulitsky I, McGeary SE, Bartel DP. Beyond secondary structure: primary-sequence determinants license pri-miRNA hairpins for processing. Cell 2013; 152:844-58. [PMID: 23415231 DOI: 10.1016/j.cell.2013.01.031] [Citation(s) in RCA: 309] [Impact Index Per Article: 28.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2012] [Revised: 10/28/2012] [Accepted: 01/14/2013] [Indexed: 12/26/2022]
Abstract
To use microRNAs to downregulate mRNA targets, cells must first process these ~22 nt RNAs from primary transcripts (pri-miRNAs). These transcripts form RNA hairpins important for processing, but additional determinants must distinguish pri-miRNAs from the many other hairpin-containing transcripts expressed in each cell. Illustrating the complexity of this recognition, we show that most Caenorhabditis elegans pri-miRNAs lack determinants required for processing in human cells. To find these determinants, we generated many variants of four human pri-miRNAs, sequenced millions that retained function, and compared them with the starting variants. Our results confirmed the importance of pairing in the stem and revealed three primary-sequence determinants, including an SRp20-binding motif (CNNC) found downstream of most pri-miRNA hairpins in bilaterian animals, but not in nematodes. Adding this and other determinants to C. elegans pri-miRNAs imparted efficient processing in human cells, thereby confirming the importance of primary-sequence determinants for distinguishing pri-miRNAs from other hairpin-containing transcripts.
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Affiliation(s)
- Vincent C Auyeung
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA
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Catania F, Lynch M. A simple model to explain evolutionary trends of eukaryotic gene architecture and expression: how competition between splicing and cleavage/polyadenylation factors may affect gene expression and splice-site recognition in eukaryotes. Bioessays 2013; 35:561-70. [PMID: 23568225 DOI: 10.1002/bies.201200127] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Enormous phylogenetic variation exists in the number and sizes of introns in protein-coding genes. Although some consideration has been given to the underlying role of the population-genetic environment in defining such patterns, the influence of the intracellular environment remains virtually unexplored. Drawing from observations on interactions between co-transcriptional processes involved in splicing and mRNA 3'-end formation, a mechanistic model is proposed for splice-site recognition that challenges the commonly accepted intron- and exon-definition models. Under the suggested model, splicing factors that outcompete 3'-end processing factors for access to intronic binding sites concurrently favor the recruitment of 3'-end processing factors at the pre-mRNA tail. This hypothesis sheds new light on observations such as the intron-mediated enhancement of gene expression and the negative correlation between intron length and levels of gene expression.
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Affiliation(s)
- Francesco Catania
- Institute for Evolution and Biodiversity, University of Münster, Münster, Germany.
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39
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Pandit S, Zhou Y, Shiue L, Coutinho-Mansfield G, Li H, Qiu J, Huang J, Yeo GW, Ares M, Fu XD. Genome-wide analysis reveals SR protein cooperation and competition in regulated splicing. Mol Cell 2013; 50:223-35. [PMID: 23562324 DOI: 10.1016/j.molcel.2013.03.001] [Citation(s) in RCA: 225] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2012] [Revised: 01/02/2013] [Accepted: 02/25/2013] [Indexed: 12/12/2022]
Abstract
SR proteins are well-characterized RNA binding proteins that promote exon inclusion by binding to exonic splicing enhancers (ESEs). However, it has been unclear whether regulatory rules deduced on model genes apply generally to activities of SR proteins in the cell. Here, we report global analyses of two prototypical SR proteins, SRSF1 (SF2/ASF) and SRSF2 (SC35), using splicing-sensitive arrays and CLIP-seq on mouse embryo fibroblasts (MEFs). Unexpectedly, we find that these SR proteins promote both inclusion and skipping of exons in vivo, but their binding patterns do not explain such opposite responses. Further analyses reveal that loss of one SR protein is accompanied by coordinated loss or compensatory gain in the interaction of other SR proteins at the affected exons. Therefore, specific effects on regulated splicing by one SR protein actually depend on a complex set of relationships with multiple other SR proteins in mammalian genomes.
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Affiliation(s)
- Shatakshi Pandit
- Department of Cellular and Molecular Medicine and Institute for Genomic Medicine, University of California, San Diego, La Jolla, CA 92093-0651, USA
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40
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Regulation of splicing by SR proteins and SR protein-specific kinases. Chromosoma 2013; 122:191-207. [PMID: 23525660 DOI: 10.1007/s00412-013-0407-z] [Citation(s) in RCA: 320] [Impact Index Per Article: 29.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2013] [Revised: 03/04/2013] [Accepted: 03/06/2013] [Indexed: 12/21/2022]
Abstract
Genomic sequencing reveals similar but limited numbers of protein-coding genes in different genomes, which begs the question of how organismal diversities are generated. Alternative pre-mRNA splicing, a widespread phenomenon in higher eukaryotic genomes, is thought to provide a mechanism to increase the complexity of the proteome and introduce additional layers for regulating gene expression in different cell types and during development. Among a large number of factors implicated in the splicing regulation are the SR protein family of splicing factors and SR protein-specific kinases. Here, we summarize the rules for SR proteins to function as splicing regulators, which depend on where they bind in exons versus intronic regions, on alternative exons versus flanking competing exons, and on cooperative as well as competitive binding between different SR protein family members on many of those locations. We review the importance of cycles of SR protein phosphorylation/dephosphorylation in the splicing reaction with emphasis on the recent molecular insight into the role of SR protein phosphorylation in early steps of spliceosome assembly. Finally, we highlight recent discoveries of SR protein-specific kinases in transducing growth signals to regulate alternative splicing in the nucleus and the connection of both SR proteins and SR protein kinases to human diseases, particularly cancer.
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41
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Walsh CM, Suchanek AL, Cyphert TJ, Kohan AB, Szeszel-Fedorowicz W, Salati LM. Serine arginine splicing factor 3 is involved in enhanced splicing of glucose-6-phosphate dehydrogenase RNA in response to nutrients and hormones in liver. J Biol Chem 2012; 288:2816-28. [PMID: 23233666 DOI: 10.1074/jbc.m112.410803] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Expression of G6PD is controlled by changes in the degree of splicing of the G6PD mRNA in response to nutrients in the diet. This regulation involves an exonic splicing enhancer (ESE) in exon 12 of the mRNA. Using the G6PD model, we demonstrate that nutrients and hormones control the activity of serine-arginine-rich (SR) proteins, a family of splicing co-activators, and thereby regulate the splicing of G6PD mRNA. In primary rat hepatocyte cultures, insulin increased the amount of phosphorylated SR proteins, and this effect was counteracted by arachidonic acid. The results of RNA affinity analysis with nuclear extracts from intact liver demonstrated that the SR splicing factor proteins SRSF3 and SRSF4 bound to the G6PD ESE. Consequently, siRNA-mediated depletion of SRSF3, but not SRSF4, in liver cells inhibited accumulation of both mRNA expressed from a minigene containing exon 12 and the endogenous G6PD mRNA. Consistent with the functional role of SRSF3 in regulating splicing, SRSF3 was observed to bind to the ESE in both intact cells and in animals using RNA immunoprecipitation analysis. Furthermore, refeeding significantly increased the binding of SRSF3 coincident with increased splicing and expression of G6PD. Together, these data establish that nutritional regulation of SRSF3 activity is involved in the differential splicing of the G6PD transcript in response to nutrients. Nutritional regulation of other SR proteins presents a regulatory mechanism that could cause widespread changes in mRNA splicing. Nutrients are therefore novel regulators of mRNA splicing.
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Affiliation(s)
- Callee M Walsh
- Department of Biochemistry, West Virginia University, Morgantown, West Virginia 26506, USA
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42
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Änkö ML, Müller-McNicoll M, Brandl H, Curk T, Gorup C, Henry I, Ule J, Neugebauer KM. The RNA-binding landscapes of two SR proteins reveal unique functions and binding to diverse RNA classes. Genome Biol 2012; 13:R17. [PMID: 22436691 PMCID: PMC3439968 DOI: 10.1186/gb-2012-13-3-r17] [Citation(s) in RCA: 197] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2012] [Revised: 03/20/2012] [Accepted: 03/21/2012] [Indexed: 01/03/2023] Open
Abstract
Background The SR proteins comprise a family of essential, structurally related RNA binding proteins. The complexity of their RNA targets and specificity of RNA recognition in vivo is not well understood. Here we use iCLIP to globally analyze and compare the RNA binding properties of two SR proteins, SRSF3 and SRSF4, in murine cells. Results SRSF3 and SRSF4 binding sites mapped to largely non-overlapping target genes, and in vivo consensus binding motifs were distinct. Interactions with intronless and intron-containing mRNAs as well as non-coding RNAs were detected. Surprisingly, both SR proteins bound to the 3' ends of the majority of intronless histone transcripts, implicating SRSF3 and SRSF4 in histone mRNA metabolism. In contrast, SRSF3 but not SRSF4 specifically bound transcripts encoding numerous RNA binding proteins. Remarkably, SRSF3 was shown to modulate alternative splicing of its own as well as three other transcripts encoding SR proteins. These SRSF3-mediated splicing events led to downregulation of heterologous SR proteins via nonsense-mediated decay. Conclusions SRSF3 and SRSF4 display unique RNA binding properties underlying diverse cellular regulatory mechanisms, with shared as well as unique coding and non-coding targets. Importantly, CLIP analysis led to the discovery that SRSF3 cross-regulates the expression of other SR protein family members.
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Affiliation(s)
- Minna-Liisa Änkö
- Max Planck Institute of Cell Biology and Genetics, Dresden, Germany.
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43
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Wei WJ, Mu SR, Heiner M, Fu X, Cao LJ, Gong XF, Bindereif A, Hui J. YB-1 binds to CAUC motifs and stimulates exon inclusion by enhancing the recruitment of U2AF to weak polypyrimidine tracts. Nucleic Acids Res 2012; 40:8622-36. [PMID: 22730292 PMCID: PMC3458536 DOI: 10.1093/nar/gks579] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The human Y box-binding protein-1 (YB-1) is a deoxyribonucleic acid (DNA)/ribonucleic acid (RNA)-binding protein with pleiotropic functions. Besides its roles in the regulation of transcription and translation, several recent studies indicate that YB-1 is a spliceosome-associated protein and is involved in alternative splicing, but the underlying mechanism has remained elusive. Here, we define both CAUC and CACC as high-affinity binding motifs for YB-1 by systematic evolution of ligands by exponential enrichment (SELEX) and demonstrate that these newly defined motifs function as splicing enhancers. Interestingly, on the endogenous CD44 gene, YB-1 appears to mediate a network interaction to activate exon v5 inclusion via multiple CAUC motifs in both the alternative exon and its upstream polypyrimidine tract. We provide evidence that YB-1 activates splicing by facilitating the recruitment of U2AF65 to weak polypyrimidine tracts through direct protein–protein interactions. Together, these findings suggest a vital role of YB-1 in activating a subset of weak 3′ splice sites in mammalian cells.
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Affiliation(s)
- Wen-Juan Wei
- State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 200031 Shanghai, China
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44
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Roca X, Karginov FV. RNA biology in a test tube--an overview of in vitro systems/assays. WILEY INTERDISCIPLINARY REVIEWS-RNA 2012; 3:509-27. [PMID: 22447682 DOI: 10.1002/wrna.1115] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
In vitro systems have provided a wealth of information in the field of RNA biology, as they constitute a superior and sometimes the unique approach to address many important questions. Such cell-free methods can be sorted by the degree of complexity of the preparation of enzymatic and/or regulatory activity. Progress in the study of pre-mRNA processing has largely relied on traditional in vitro methods, as these reactions have been recapitulated in cell-free systems. The pre-mRNA capping, editing, and cleavage/polyadenylation reactions have even been reconstituted using purified components, and the enzymes responsible for catalysis have been characterized by such techniques. In vitro splicing using nuclear or cytoplasmic extracts has yielded clues on spliceosome assembly, kinetics, and mechanisms of splicing and has been essential to elucidate the function of splicing factors. Coupled systems have been important to functionally connect distinct processes, like transcription and splicing. Extract preparation has also been adapted to cells from a variety of tissues and species, revealing general versus species-specific mechanisms. Cell-free assays have also been applied to newly discovered pathways such as those involving small RNAs, including microRNAs (miRNAs), small interfering RNAs (siRNAs), and Piwi-interacting RNAs (piRNAs). The first two pathways have been well characterized largely by in vitro methods, which need to be developed for piRNAs. Finally, new techniques, such as single-molecule studies, are continuously being established, providing new and important insights into the field. Thus, in vitro approaches have been, are, and will continue being at the forefront of RNA research.
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Affiliation(s)
- Xavier Roca
- Division of Molecular Genetics & Cell Biology, School of Biological Sciences, Nanyang Technological University, Singapore, Singapore.
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45
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Ankö ML, Neugebauer KM. RNA-protein interactions in vivo: global gets specific. Trends Biochem Sci 2012; 37:255-62. [PMID: 22425269 DOI: 10.1016/j.tibs.2012.02.005] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2011] [Revised: 02/05/2012] [Accepted: 02/08/2012] [Indexed: 01/01/2023]
Abstract
RNA-binding proteins (RBPs) impact every process in the cell; they act as splicing and polyadenylation factors, transport and localization factors, stabilizers and destabilizers, modifiers, and chaperones. RNA-binding capacity can be attributed to numerous protein domains that bind a limited repertoire of short RNA sequences. How is specificity achieved in cells? Here we focus on recent advances in determining the RNA-binding properties of proteins in vivo and compare these to in vitro determinations, highlighting insights into how endogenous RNA molecules are recognized and regulated. We also discuss the crucial contribution of structural determinations for understanding RNA-binding specificity and mechanisms.
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Affiliation(s)
- Minna-Liisa Ankö
- Max Planck Institute of Cell Biology and Genetics, Dresden, Germany.
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46
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Wang Z, Chatterjee D, Jeon HY, Akerman M, Vander Heiden MG, Cantley LC, Krainer AR. Exon-centric regulation of pyruvate kinase M alternative splicing via mutually exclusive exons. J Mol Cell Biol 2011; 4:79-87. [PMID: 22044881 DOI: 10.1093/jmcb/mjr030] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Alternative splicing of the pyruvate kinase M gene (PK-M) can generate the M2 isoform and promote aerobic glycolysis and tumor growth. However, the cancer-specific alternative splicing regulation of PK-M is not completely understood. Here, we demonstrate that PK-M is regulated by reciprocal effects on the mutually exclusive exons 9 and 10, such that exon 9 is repressed and exon 10 is activated in cancer cells. Strikingly, exonic, rather than intronic, cis-elements are key determinants of PK-M splicing isoform ratios. Using a systematic sub-exonic duplication approach, we identify a potent exonic splicing enhancer in exon 10, which differs from its homologous counterpart in exon 9 by only two nucleotides. We identify SRSF3 as one of the cognate factors, and show that this serine/arginine-rich protein activates exon 10 and mediates changes in glucose metabolism. These findings provide mechanistic insights into the complex regulation of alternative splicing of a key regulator of the Warburg effect, and also have implications for other genes with a similar pattern of alternative splicing.
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Affiliation(s)
- Zhenxun Wang
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA
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47
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Daubner GM, Cléry A, Jayne S, Stevenin J, Allain FHT. A syn-anti conformational difference allows SRSF2 to recognize guanines and cytosines equally well. EMBO J 2011; 31:162-74. [PMID: 22002536 DOI: 10.1038/emboj.2011.367] [Citation(s) in RCA: 107] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2011] [Accepted: 09/12/2011] [Indexed: 11/09/2022] Open
Abstract
SRSF2 (SC35) is a key player in the regulation of alternative splicing events and binds degenerated RNA sequences with similar affinity in nanomolar range. We have determined the solution structure of the SRSF2 RRM bound to the 5'-UCCAGU-3' and 5'-UGGAGU-3' RNA, both identified as SRSF2 binding sites in the HIV-1 tat exon 2. RNA recognition is achieved through a novel sandwich-like structure with both termini forming a positively charged cavity to accommodate the four central nucleotides. To bind both RNA sequences equally well, SRSF2 forms a nearly identical network of intermolecular interactions by simply flipping the bases of the two consecutive C or G nucleotides into either anti or syn conformation. We validate this unusual mode of RNA recognition functionally by in-vitro and in-vivo splicing assays and propose a 5'-SSNG-3' (S=C/G) high-affinity binding consensus sequence for SRSF2. In conclusion, in addition to describe for the first time the RNA recognition mode of SRSF2, we provide the precise consensus sequence to identify new putative binding sites for this splicing factor.
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Affiliation(s)
- Gerrit M Daubner
- Institute of Molecular Biology and Biophysics, ETH Zürich, Zürich, Switzerland
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48
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Cho S, Hoang A, Chakrabarti S, Huynh N, Huang DB, Ghosh G. The SRSF1 linker induces semi-conservative ESE binding by cooperating with the RRMs. Nucleic Acids Res 2011; 39:9413-21. [PMID: 21852328 PMCID: PMC3241662 DOI: 10.1093/nar/gkr663] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
SR proteins promote spliceosome formation by recognizing exonic splicing enhancers (ESEs) during pre-mRNA splicing. Each SR protein binds diverse ESEs using strategies that are yet to be elucidated. Here, we show that the RNA-binding domain (RBD) of SRSF1 optimally binds to decameric purine rich ESE sequences although locations of purines are not stringently specified. The presence of uracils either within or outside of the recognition site is detrimental for binding with SRSF1. The entire RBD, comprised of two RRMs and a glycine-rich linker, is essential for ESE binding. Mutation within each segment reduced or nearly abolished binding, suggesting that these segments mediate cooperative binding. The linker plays a decisive role in organizing ESE binding. The flanking basic regions of the linker appear to communicate with each other in bringing the two RRMs close together to form the complex with RNA. Our study thus suggests semi-conservative adaptable interaction between ESE and SRSF1, and such binding mode is not only essential for the recognition of plethora of physiological ESE sequences but may also be essential for the interaction with various factors during the spliceosome assembly.
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Affiliation(s)
- Suhyung Cho
- Department of Chemistry & Biochemistry, University of California, San Diego 9500 Gilman Drive, La Jolla, CA 92093, USA
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49
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Qian W, Liang H, Shi J, Jin N, Grundke-Iqbal I, Iqbal K, Gong CX, Liu F. Regulation of the alternative splicing of tau exon 10 by SC35 and Dyrk1A. Nucleic Acids Res 2011; 39:6161-71. [PMID: 21470964 PMCID: PMC3152345 DOI: 10.1093/nar/gkr195] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2010] [Revised: 03/16/2011] [Accepted: 03/17/2011] [Indexed: 12/16/2022] Open
Abstract
Abnormal alternative splicing of tau exon 10 results in imbalance of 3R-tau and 4R-tau expression, which is sufficient to cause neurofibrillary degeneration. Splicing factor SC35, a member of the superfamily of the serine/arginine-rich (SR) proteins, promotes tau exon 10 inclusion. The molecular mechanism by which SC35 participates in tau exon 10 splicing remains elusive. In the present study, we found that tau pre-mRNA was coprecipitated by SC35 tagged with HA. Mutation of the SC35-like exonic splicing enhancer located at exon 10 of tau affected both the binding of SC35 to tau pre-mRNA and promotion of tau exon 10 inclusion, suggesting that SC35 acts on the SC35-like exonic splicing enhancer to promote tau exon 10 inclusion. Dyrk1A (dual-specificity tyrosine-phosphorylated and regulated kinase 1A) phosphorylated SC35 in vitro and interacted with it in cultured cells. Overexpression of Dyrk1A suppressed SC35's ability to promote tau exon 10 inclusion. Downregulation of Dyrk1A promoted 4R-tau expression. Therefore, upregulation of Dyrk1A in Down syndrome brain or Alzheimer's brain may cause dysregulation of tau exon 10 splicing through SC35, and probably together with other splicing factors, leading to the imbalance in 3R-tau and 4R-tau expression, which may initiate or accelerate tau pathology and cause neurofibrillary degeneration in the diseases.
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Affiliation(s)
- Wei Qian
- Jiangsu Key Laboratory of Neuroregeneration, Department of Biochemistry, Medical School, Nantong University, Nantong, Jiangsu, P. R. China and Department of Neurochemistry, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, NY, USA
| | - Hongwei Liang
- Jiangsu Key Laboratory of Neuroregeneration, Department of Biochemistry, Medical School, Nantong University, Nantong, Jiangsu, P. R. China and Department of Neurochemistry, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, NY, USA
| | - Jianhua Shi
- Jiangsu Key Laboratory of Neuroregeneration, Department of Biochemistry, Medical School, Nantong University, Nantong, Jiangsu, P. R. China and Department of Neurochemistry, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, NY, USA
| | - Nana Jin
- Jiangsu Key Laboratory of Neuroregeneration, Department of Biochemistry, Medical School, Nantong University, Nantong, Jiangsu, P. R. China and Department of Neurochemistry, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, NY, USA
| | - Inge Grundke-Iqbal
- Jiangsu Key Laboratory of Neuroregeneration, Department of Biochemistry, Medical School, Nantong University, Nantong, Jiangsu, P. R. China and Department of Neurochemistry, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, NY, USA
| | - Khalid Iqbal
- Jiangsu Key Laboratory of Neuroregeneration, Department of Biochemistry, Medical School, Nantong University, Nantong, Jiangsu, P. R. China and Department of Neurochemistry, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, NY, USA
| | - Cheng-Xin Gong
- Jiangsu Key Laboratory of Neuroregeneration, Department of Biochemistry, Medical School, Nantong University, Nantong, Jiangsu, P. R. China and Department of Neurochemistry, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, NY, USA
| | - Fei Liu
- Jiangsu Key Laboratory of Neuroregeneration, Department of Biochemistry, Medical School, Nantong University, Nantong, Jiangsu, P. R. China and Department of Neurochemistry, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, NY, USA
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50
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Ke S, Shang S, Kalachikov SM, Morozova I, Yu L, Russo JJ, Ju J, Chasin LA. Quantitative evaluation of all hexamers as exonic splicing elements. Genome Res 2011; 21:1360-74. [PMID: 21659425 DOI: 10.1101/gr.119628.110] [Citation(s) in RCA: 170] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
We describe a comprehensive quantitative measure of the splicing impact of a complete set of RNA 6-mer sequences by deep sequencing successfully spliced transcripts. All 4096 6-mers were substituted at five positions within two different internal exons in a 3-exon minigene, and millions of successfully spliced transcripts were sequenced after transfection of human cells. The results allowed the assignment of a relative splicing strength score to each mutant molecule. The effect of 6-mers on splicing often depended on their location; much of this context effect could be ascribed to the creation of different overlapping sequences at each site. Taking these overlaps into account, the splicing effect of each 6-mer could be quantified, and 6-mers could be designated as enhancers (ESEseqs) and silencers (ESSseqs), with an ESRseq score indicating their strength. Some 6-mers exhibited positional bias relative to the two splice sites. The distribution and conservation of these ESRseqs in and around human exons supported their classification. Predicted RNA secondary structure effects were also seen: Effective enhancers, silencers and 3' splice sites tend to be single stranded, and effective 5' splice sites tend to be double stranded. 6-mers that may form positive or negative synergy with another were also identified. Chromatin structure may also influence the splicing enhancement observed, as a good correspondence was found between splicing performance and the predicted nucleosome occupancy scores of 6-mers. This approach may prove of general use in defining nucleic acid regulatory motifs, substitute for functional SELEX in most cases, and provide insights about splicing mechanisms.
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Affiliation(s)
- Shengdong Ke
- Department of Biological Sciences, Columbia University, New York, New York 10027, USA
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