1
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Tan CW, Sim DY, Zhen Y, Tian H, Koh J, Roca X. PRPF40A induces inclusion of exons in GC-rich regions important for human myeloid cell differentiation. Nucleic Acids Res 2024:gkae557. [PMID: 38943321 DOI: 10.1093/nar/gkae557] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2023] [Revised: 06/07/2024] [Accepted: 06/19/2024] [Indexed: 07/01/2024] Open
Abstract
We characterized the regulatory mechanisms and role in human myeloid cell survival and differentiation of PRPF40A, a splicing factor lacking a canonical RNA Binding Domain. Upon PRPF40A knockdown, HL-60 cells displayed increased cell death, decreased proliferation and slight differentiation phenotype with upregulation of immune activation genes. Suggestive of both redundant and specific functions, cell death but not proliferation was rescued by overexpression of its paralog PRPF40B. Transcriptomic analysis revealed the predominant role of PRPF40A as an activator of cassette exon inclusion of functionally relevant splicing events. Mechanistically, the exons exclusively upregulated by PRPF40A are flanked by short and GC-rich introns which tend to localize to nuclear speckles in the nucleus center. These PRPF40A regulatory features are shared with other splicing regulators such as SRRM2, SON, PCBP1/2, and to a lesser extent TRA2B and SRSF2, as a part of a functional network that regulates splicing partly via co-localization in the nucleus.
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Affiliation(s)
- Cheryl Weiqi Tan
- School of Biological Sciences, Nanyang Technological University, 637551 Singapore
| | - Donald Yuhui Sim
- School of Biological Sciences, Nanyang Technological University, 637551 Singapore
| | - Yashu Zhen
- School of Biological Sciences, Nanyang Technological University, 637551 Singapore
| | - Haobo Tian
- School of Biological Sciences, Nanyang Technological University, 637551 Singapore
| | - Jace Koh
- School of Biological Sciences, Nanyang Technological University, 637551 Singapore
| | - Xavier Roca
- School of Biological Sciences, Nanyang Technological University, 637551 Singapore
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2
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Martínez-Lumbreras S, Träger LK, Mulorz MM, Payr M, Dikaya V, Hipp C, König J, Sattler M. Intramolecular autoinhibition regulates the selectivity of PRPF40A tandem WW domains for proline-rich motifs. Nat Commun 2024; 15:3888. [PMID: 38719828 PMCID: PMC11079029 DOI: 10.1038/s41467-024-48004-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2023] [Accepted: 04/18/2024] [Indexed: 05/12/2024] Open
Abstract
PRPF40A plays an important role in the regulation of pre-mRNA splicing by mediating protein-protein interactions in the early steps of spliceosome assembly. By binding to proteins at the 5´ and 3´ splice sites, PRPF40A promotes spliceosome assembly by bridging the recognition of the splices. The PRPF40A WW domains are expected to recognize proline-rich sequences in SF1 and SF3A1 in the early spliceosome complexes E and A, respectively. Here, we combine NMR, SAXS and ITC to determine the structure of the PRPF40A tandem WW domains in solution and characterize the binding specificity and mechanism for proline-rich motifs recognition. Our structure of the PRPF40A WW tandem in complex with a high-affinity SF1 peptide reveals contributions of both WW domains, which also enables tryptophan sandwiching by two proline residues in the ligand. Unexpectedly, a proline-rich motif in the N-terminal region of PRPF40A mediates intramolecular interactions with the WW tandem. Using NMR, ITC, mutational analysis in vitro, and immunoprecipitation experiments in cells, we show that the intramolecular interaction acts as an autoinhibitory filter for proof-reading of high-affinity proline-rich motifs in bona fide PRPF40A binding partners. We propose that similar autoinhibitory mechanisms are present in most WW tandem-containing proteins to enhance binding selectivity and regulation of WW/proline-rich peptide interaction networks.
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Affiliation(s)
- Santiago Martínez-Lumbreras
- Institute of Structural Biology, Molecular Targets and Therapeutics Center, Helmholtz Munich, Ingolstädter Landstrasse 1, 85764, Neuherberg, Germany.
- TUM School of Natural Sciences, Department of Bioscience and Bavarian NMR Center, Technical University of Munich, Lichtenbergstrasse 4, 85748, Garching, Germany.
| | - Lena K Träger
- TUM School of Natural Sciences, Department of Bioscience and Bavarian NMR Center, Technical University of Munich, Lichtenbergstrasse 4, 85748, Garching, Germany
| | - Miriam M Mulorz
- Institute of Molecular Biology (IMB) gGmbH, Ackermannweg 4, 55128, Mainz, Germany
| | - Marco Payr
- TUM School of Natural Sciences, Department of Bioscience and Bavarian NMR Center, Technical University of Munich, Lichtenbergstrasse 4, 85748, Garching, Germany
| | - Varvara Dikaya
- TUM School of Natural Sciences, Department of Bioscience and Bavarian NMR Center, Technical University of Munich, Lichtenbergstrasse 4, 85748, Garching, Germany
| | - Clara Hipp
- Institute of Structural Biology, Molecular Targets and Therapeutics Center, Helmholtz Munich, Ingolstädter Landstrasse 1, 85764, Neuherberg, Germany
- TUM School of Natural Sciences, Department of Bioscience and Bavarian NMR Center, Technical University of Munich, Lichtenbergstrasse 4, 85748, Garching, Germany
| | - Julian König
- Institute of Molecular Biology (IMB) gGmbH, Ackermannweg 4, 55128, Mainz, Germany
| | - Michael Sattler
- Institute of Structural Biology, Molecular Targets and Therapeutics Center, Helmholtz Munich, Ingolstädter Landstrasse 1, 85764, Neuherberg, Germany.
- TUM School of Natural Sciences, Department of Bioscience and Bavarian NMR Center, Technical University of Munich, Lichtenbergstrasse 4, 85748, Garching, Germany.
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3
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Chen X, Dong X, Li H, Wu T, Liu H, Wu J, Ge W, Hao L, Zhang Z. RNA-binding proteins signature is a favorable biomarker of prognosis, immunotherapy and chemotherapy response for cervical cancer. Cancer Cell Int 2024; 24:80. [PMID: 38383371 PMCID: PMC10882920 DOI: 10.1186/s12935-024-03257-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2023] [Accepted: 02/02/2024] [Indexed: 02/23/2024] Open
Abstract
Cervical squamous cell carcinoma and endocervical adenocarcinoma (CESC) still present a huge threaten to women's health, especially the local advanced patients. Hence, developing more effectiveness prognostic signatures is urgently needed. This study constructed and verified a robust RNA-binding proteins (RBPs) related signature through a series of bioinformatics methods and explored the biological function of hub RBP in vitro experiments. As a result, the 10 RBPs signature was successfully established and could act as an independent prognostic biomarker in CESC patients, which displayed the highest sensitivity and specificity in prognosis prediction compared with other clinicopathological parameters. The risk model also presented good performance in risk stratification among CESC patients. Besides, a nomogram was constructed based on pathological stage and the risk signature and exhibited satisfactory accuracy in prognosis prediction. Functional enrichment indicated that the risk signature mainly participated in immune-related pathways and cancer-related pathways, and the infiltration level of immune cells and immune checkpoints showed a significantly higher degree in low-risk patients compared with high-risk patients. Notably, the 10 RBPs signature act as a novel biomarker in immunotherapy and chemotherapy response. In addition, PRPF40B was selected as hub RBP and its transcription and translation levels were obviously increased in CESC tissues, as well as Hela and Siha cells. Knockdown of PRPF40B inhibits the proliferation, migration and invasion of Hela and Siha cells in vitro. In conclusion, our research provides a noticeable strategy in prognostic prediction among CESC patients, which may illuminate the prospect of CESC patients' clinical outcome.
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Affiliation(s)
- Xiaomei Chen
- Nursing Department, Medical Centre Hospital of Qionglai City, Qionglai, 611530, Sichuan, China
| | - Xunhu Dong
- Institute of Toxicology, School of Military Preventive Medicine, Third Military Medical University (Army Medical University), 30 Gaotanyan Street, Shapingba District, Chongqing, 400038, China
| | - Hong Li
- Department of Obstetrics and Gynecology, Xinqiao Hospital, Third Military Medical University (Army Medical University), Chongqing, 400038, China
| | - Tingting Wu
- Department of Obstetrics and Gynecology, Southwest Hospital, Third Military Medical University (Army Medical University), Chongqing, 400037, China
| | - Haoyin Liu
- Institute of Toxicology, School of Military Preventive Medicine, Third Military Medical University (Army Medical University), 30 Gaotanyan Street, Shapingba District, Chongqing, 400038, China
| | - Jie Wu
- Institute of Toxicology, School of Military Preventive Medicine, Third Military Medical University (Army Medical University), 30 Gaotanyan Street, Shapingba District, Chongqing, 400038, China
| | - Wei Ge
- Institute of Toxicology, School of Military Preventive Medicine, Third Military Medical University (Army Medical University), 30 Gaotanyan Street, Shapingba District, Chongqing, 400038, China
| | - Lingji Hao
- Department of Obstetrics and Gynecology, Xinqiao Hospital, Third Military Medical University (Army Medical University), Chongqing, 400038, China
| | - Zhe Zhang
- Institute of Toxicology, School of Military Preventive Medicine, Third Military Medical University (Army Medical University), 30 Gaotanyan Street, Shapingba District, Chongqing, 400038, China.
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Espinosa S, De Bortoli F, Li X, Rossi J, Wagley ME, Lo HYG, Taliaferro JM, Zhao R. Human PRPF39 is an alternative splicing factor recruiting U1 snRNP to weak 5' splice sites. RNA (NEW YORK, N.Y.) 2022; 29:rna.079320.122. [PMID: 36316087 PMCID: PMC9808567 DOI: 10.1261/rna.079320.122] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Accepted: 10/24/2022] [Indexed: 06/16/2023]
Abstract
Human PRPF39 is a homolog of the yeast Prp39 and Prp42 paralogs. We have previously shown that human PRPF39 forms a homodimer that interacts with the CTD of U1C, mirroring the yeast Prp39/Prp42 heterodimer. We demonstrate here that PRPF39 knockdown in HEK293 cells affects many alternative splicing events primarily by reducing the usage of weak 5'ss. Additionally, PRPF39 preferentially binds to a GC-rich RNA, likely at the interface between its NTD and CTD. These data indicate that PRPF39 potentially recruits U1 snRNP to a weak 5' ss, serving as a previously unrecognized alternative splicing factor. We further demonstrate that human TIA1 binds to U1C through its RRM1 and RRM3+Q domains but has no significant binding to PRPF39. Finally, all three human LUC7L isoforms directly interact with U1C. These results reveal significant parallels to the yeast U1 snRNP structure and support the use of yeast U1 snRNP as a model for understanding the mechanism of human alternative splicing.
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Affiliation(s)
- Sara Espinosa
- University of Colorado Denver Anschutz Medical Campus
| | | | - Xueni Li
- University of Colorado Denver Anschutz Medical Campus
| | - John Rossi
- University of Colorado Denver Anschutz Medical Campus
| | | | - Hei-Yong G Lo
- University of Colorado Denver Anschutz Medical Campus
| | | | - Rui Zhao
- University of Colorado Denver Anschutz Medical Campus
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5
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Muehlbauer LK, Wei T, Shishkova E, Coon JJ, Lambert PF. IQGAP1 and RNA Splicing in the Context of Head and Neck via Phosphoproteomics. J Proteome Res 2022; 21:2211-2223. [PMID: 35980772 PMCID: PMC9833422 DOI: 10.1021/acs.jproteome.2c00309] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
IQGAP1 (IQ motif-containing GTPase-activating protein 1) scaffolds several signaling pathways in mammalian cells that are implicated in carcinogenesis, including the RAS and PI3K pathways that involve multiple protein kinases. IQGAP1 has been shown to promote head and neck squamous cell carcinoma (HNSCC); however, the underlying mechanism(s) remains unclear. Here, we report a mass spectrometry-based analysis identifying differences in phosphorylation of cellular proteins in vivo and in vitro in the presence or absence of IQGAP1. By comparing the esophageal phosphoproteome profiles between Iqgap1+/+ and Iqgap1-/- mice, we identified RNA splicing as one of the most altered cellular processes. Serine/arginine-rich splicing factor 6 (SRSF6) was the protein with the most downregulated levels of phosphorylation in Iqgap1-/- tissue. We confirmed that the absence of IQGAP1 reduced SRSF6 phosphorylation both in vivo and in vitro. We then expanded our analysis to human normal oral keratinocytes. Again, we found factors involved in RNA splicing to be highly altered in the phosphoproteome profile upon genetic disruption of IQGAP1. Both the Clinical Proteomic Tumor Analysis Consortium (CPTAC) and the Cancer Genome Atlas (TCGA) data sets indicate that phosphorylation of splicing-related proteins is important in HNSCC prognosis. The Biological General Repository for Interaction Datasets (BioGRID) repository also suggested multiple interactions between IQGAP1 and splicing-related proteins. Based on these collective observations, we propose that IQGAP1 regulates the phosphorylation of splicing proteins, which potentially affects their splicing activities and, therefore, contributes to HNSCC. Raw data are available from the MassIVE database with identifier MSV000087770.
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Affiliation(s)
- Laura K. Muehlbauer
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Tao Wei
- McArdle Laboratory for Cancer Research, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, 53705, USA
| | - Evgenia Shishkova
- Department of Biomolecular Chemistry, University of Wisconsin-Madison, Madison, WI, 53706, USA
- National Center for Quantitative Biology of Complex Systems, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Joshua J. Coon
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, 53706, USA
- Department of Biomolecular Chemistry, University of Wisconsin-Madison, Madison, WI, 53706, USA
- National Center for Quantitative Biology of Complex Systems, University of Wisconsin-Madison, Madison, WI 53706, USA
- Morgridge Institute for Research, Madison, WI 53706, USA
| | - Paul F. Lambert
- McArdle Laboratory for Cancer Research, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, 53705, USA
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6
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Li J, Kalev-Zylinska ML. Advances in molecular characterization of myeloid proliferations associated with Down syndrome. Front Genet 2022; 13:891214. [PMID: 36035173 PMCID: PMC9399805 DOI: 10.3389/fgene.2022.891214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Accepted: 07/11/2022] [Indexed: 11/13/2022] Open
Abstract
Myeloid leukemia associated with Down syndrome (ML-DS) has a unique molecular landscape that differs from other subtypes of acute myeloid leukemia. ML-DS is often preceded by a myeloproliferative neoplastic condition called transient abnormal myelopoiesis (TAM) that disrupts megakaryocytic and erythroid differentiation. Over the last two decades, many genetic and epigenetic changes in TAM and ML-DS have been elucidated. These include overexpression of molecules and micro-RNAs located on chromosome 21, GATA1 mutations, and a range of other somatic mutations and chromosomal alterations. In this review, we summarize molecular changes reported in TAM and ML-DS and provide a comprehensive discussion of these findings. Recent advances in the development of CRISPR/Cas9-modified induced pluripotent stem cell-based disease models are also highlighted. However, despite significant progress in this area, we still do not fully understand the pathogenesis of ML-DS, and there are no targeted therapies. Initial diagnosis of ML-DS has a favorable prognosis, but refractory and relapsed disease can be difficult to treat; therapeutic options are limited in Down syndrome children by their stronger sensitivity to the toxic effects of chemotherapy. Because of the rarity of TAM and ML-DS, large-scale multi-center studies would be helpful to advance molecular characterization of these diseases at different stages of development and progression.
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Affiliation(s)
- Jixia Li
- Blood and Cancer Biology Laboratory, Department of Molecular Medicine and Pathology, University of Auckland, Auckland, New Zealand
- Department of Laboratory Medicine, School of Medicine, Foshan University, Foshan, China
- *Correspondence: Jixia Li, ; Maggie L. Kalev-Zylinska,
| | - Maggie L. Kalev-Zylinska
- Blood and Cancer Biology Laboratory, Department of Molecular Medicine and Pathology, University of Auckland, Auckland, New Zealand
- Haematology Laboratory, Department of Pathology and Laboratory Medicine, Auckland City Hospital, Auckland, New Zealand
- *Correspondence: Jixia Li, ; Maggie L. Kalev-Zylinska,
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7
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Xu S, Lai SK, Sim DY, Ang W, Li HY, Roca X. SRRM2 organizes splicing condensates to regulate alternative splicing. Nucleic Acids Res 2022; 50:8599-8614. [PMID: 35929045 PMCID: PMC9410892 DOI: 10.1093/nar/gkac669] [Citation(s) in RCA: 26] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Revised: 06/29/2022] [Accepted: 08/04/2022] [Indexed: 12/27/2022] Open
Abstract
SRRM2 is a nuclear-speckle marker containing multiple disordered domains, whose dysfunction is associated with several human diseases. Using mainly EGFP-SRRM2 knock-in HEK293T cells, we show that SRRM2 forms biomolecular condensates satisfying most hallmarks of liquid-liquid phase separation, including spherical shape, dynamic rearrangement, coalescence and concentration dependence supported by in vitro experiments. Live-cell imaging shows that SRRM2 organizes nuclear speckles along the cell cycle. As bona-fide splicing factor present in spliceosome structures, SRRM2 deficiency induces skipping of cassette exons with short introns and weak splice sites, tending to change large protein domains. In THP-1 myeloid-like cells, SRRM2 depletion compromises cell viability, upregulates differentiation markers, and sensitizes cells to anti-leukemia drugs. SRRM2 induces a FES splice isoform that attenuates innate inflammatory responses, and MUC1 isoforms that undergo shedding with oncogenic properties. We conclude that SRRM2 acts as a scaffold to organize nuclear speckles, regulating alternative splicing in innate immunity and cell homeostasis.
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Affiliation(s)
- Shaohai Xu
- School of Biological Sciences, Nanyang Technological University, 637551 Singapore
| | - Soak-Kuan Lai
- School of Biological Sciences, Nanyang Technological University, 637551 Singapore
| | - Donald Yuhui Sim
- School of Biological Sciences, Nanyang Technological University, 637551 Singapore
| | | | - Hoi Yeung Li
- School of Biological Sciences, Nanyang Technological University, 637551 Singapore
| | - Xavier Roca
- To whom correspondence should be addressed. Tel: +65 65927561;
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8
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Peng Q, Zhou Y, Oyang L, Wu N, Tang Y, Su M, Luo X, Wang Y, Sheng X, Ma J, Liao Q. Impacts and mechanisms of alternative mRNA splicing in cancer metabolism, immune response, and therapeutics. Mol Ther 2022; 30:1018-1035. [PMID: 34793975 PMCID: PMC8899522 DOI: 10.1016/j.ymthe.2021.11.010] [Citation(s) in RCA: 28] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Revised: 10/29/2021] [Accepted: 11/11/2021] [Indexed: 02/08/2023] Open
Abstract
Alternative pre-mRNA splicing (AS) provides the potential to produce diversity at RNA and protein levels. Disruptions in the regulation of pre-mRNA splicing can lead to diseases. With the development of transcriptome and genome sequencing technology, increasing diseases have been identified to be associated with abnormal splicing of mRNAs. In tumors, abnormal alternative splicing frequently plays critical roles in cancer pathogenesis and may be considered as new biomarkers and therapeutic targets for cancer intervention. Metabolic abnormalities and immune disorders are important hallmarks of cancer. AS produces multiple different isoforms and diversifies protein expression, which is utilized by the immune and metabolic reprogramming systems to expand gene functions. The abnormal splicing events contributed to tumor progression, partially due to effects on immune response and metabolic reprogramming. Herein, we reviewed the vital role of alternative splicing in regulating cancer metabolism and immune response. We discussed how alternative splicing regulates metabolic reprogramming of cancer cells and antitumor immune response, and the possible strategies to targeting alternative splicing pathways or splicing-regulated metabolic pathway in the context of anticancer immunotherapy. Further, we highlighted the challenges and discuss the perspectives for RNA-based strategies for the treatment of cancer with abnormally alternative splicing isoforms.
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Affiliation(s)
- Qiu Peng
- Hunan Key Laboratory of Cancer Metabolism, Hunan Cancer Hospital and the Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, 410013 Hunan, China,Cancer Research Institute and School of Basic Medical Science, Central South University, Changsha, China
| | - Yujuan Zhou
- Hunan Key Laboratory of Cancer Metabolism, Hunan Cancer Hospital and the Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, 410013 Hunan, China,Hunan Key Laboratory of Translational Radiation Oncology, 283 Tongzipo Road, Changsha 410013, Hunan, China
| | - Linda Oyang
- Hunan Key Laboratory of Cancer Metabolism, Hunan Cancer Hospital and the Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, 410013 Hunan, China
| | - Nayiyuan Wu
- Hunan Key Laboratory of Cancer Metabolism, Hunan Cancer Hospital and the Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, 410013 Hunan, China
| | - Yanyan Tang
- Hunan Key Laboratory of Cancer Metabolism, Hunan Cancer Hospital and the Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, 410013 Hunan, China
| | - Min Su
- Hunan Key Laboratory of Cancer Metabolism, Hunan Cancer Hospital and the Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, 410013 Hunan, China
| | - Xia Luo
- Hunan Key Laboratory of Cancer Metabolism, Hunan Cancer Hospital and the Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, 410013 Hunan, China
| | - Ying Wang
- Hunan Key Laboratory of Cancer Metabolism, Hunan Cancer Hospital and the Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, 410013 Hunan, China
| | - Xiaowu Sheng
- Hunan Key Laboratory of Cancer Metabolism, Hunan Cancer Hospital and the Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, 410013 Hunan, China
| | - Jian Ma
- Hunan Key Laboratory of Cancer Metabolism, Hunan Cancer Hospital and the Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, 410013 Hunan, China; Cancer Research Institute and School of Basic Medical Science, Central South University, Changsha, China.
| | - Qianjin Liao
- Hunan Key Laboratory of Cancer Metabolism, Hunan Cancer Hospital and the Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, 410013 Hunan, China; Hunan Key Laboratory of Translational Radiation Oncology, 283 Tongzipo Road, Changsha 410013, Hunan, China.
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9
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Borao S, Ayté J, Hümmer S. Evolution of the Early Spliceosomal Complex-From Constitutive to Regulated Splicing. Int J Mol Sci 2021; 22:ijms222212444. [PMID: 34830325 PMCID: PMC8624252 DOI: 10.3390/ijms222212444] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Revised: 11/15/2021] [Accepted: 11/16/2021] [Indexed: 12/14/2022] Open
Abstract
Pre-mRNA splicing is a major process in the regulated expression of genes in eukaryotes, and alternative splicing is used to generate different proteins from the same coding gene. Splicing is a catalytic process that removes introns and ligates exons to create the RNA sequence that codifies the final protein. While this is achieved in an autocatalytic process in ancestral group II introns in prokaryotes, the spliceosome has evolved during eukaryogenesis to assist in this process and to finally provide the opportunity for intron-specific splicing. In the early stage of splicing, the RNA 5' and 3' splice sites must be brought within proximity to correctly assemble the active spliceosome and perform the excision and ligation reactions. The assembly of this first complex, termed E-complex, is currently the least understood process. We focused in this review on the formation of the E-complex and compared its composition and function in three different organisms. We highlight the common ancestral mechanisms in S. cerevisiae, S. pombe, and mammals and conclude with a unifying model for intron definition in constitutive and regulated co-transcriptional splicing.
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Affiliation(s)
- Sonia Borao
- Oxidative Stress and Cell Cycle Group, Universitat Pompeu Fabra, 08003 Barcelona, Spain;
| | - José Ayté
- Oxidative Stress and Cell Cycle Group, Universitat Pompeu Fabra, 08003 Barcelona, Spain;
- Correspondence: (J.A.); (S.H.)
| | - Stefan Hümmer
- Oxidative Stress and Cell Cycle Group, Universitat Pompeu Fabra, 08003 Barcelona, Spain;
- Translational Molecular Pathology, Vall d’Hebron Research Institute (VHIR), CIBERONC, 08035 Barcelona, Spain
- Correspondence: (J.A.); (S.H.)
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10
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Shen J, Varshney D, Simeone A, Zhang X, Adhikari S, Tannahill D, Balasubramanian S. Promoter G-quadruplex folding precedes transcription and is controlled by chromatin. Genome Biol 2021; 22:143. [PMID: 33962653 PMCID: PMC8103603 DOI: 10.1186/s13059-021-02346-7] [Citation(s) in RCA: 51] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Accepted: 04/09/2021] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Four-stranded G-quadruplexes (G4s) are DNA secondary structures in the human genome that are primarily found in active promoters associated with elevated transcription. Here, we explore the relationship between the folding of promoter G4s, transcription and chromatin state. RESULTS Transcriptional inhibition by DRB or by triptolide reveals that promoter G4 formation, as assessed by G4 ChIP-seq, does not depend on transcriptional activity. We then show that chromatin compaction can lead to loss of promoter G4s and is accompanied by a corresponding loss of RNA polymerase II (Pol II), thus establishing a link between G4 formation and chromatin accessibility. Furthermore, pre-treatment of cells with a G4-stabilising ligand mitigates the loss of Pol II at promoters induced by chromatin compaction. CONCLUSIONS Overall, our findings show that G4 folding is coupled to the establishment of accessible chromatin and does not require active transcription.
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Affiliation(s)
- Jiazhen Shen
- Li Ka Shing Centre, Cancer Research UK Cambridge Institute, Robinson Way, Cambridge, CB2 0RE, UK
| | - Dhaval Varshney
- Li Ka Shing Centre, Cancer Research UK Cambridge Institute, Robinson Way, Cambridge, CB2 0RE, UK
| | - Angela Simeone
- Li Ka Shing Centre, Cancer Research UK Cambridge Institute, Robinson Way, Cambridge, CB2 0RE, UK
| | - Xiaoyun Zhang
- Yusuf Hamied Department of Chemistry, University of Cambridge, Cambridge, CB2 1EW, UK
| | - Santosh Adhikari
- Yusuf Hamied Department of Chemistry, University of Cambridge, Cambridge, CB2 1EW, UK
| | - David Tannahill
- Li Ka Shing Centre, Cancer Research UK Cambridge Institute, Robinson Way, Cambridge, CB2 0RE, UK
| | - Shankar Balasubramanian
- Li Ka Shing Centre, Cancer Research UK Cambridge Institute, Robinson Way, Cambridge, CB2 0RE, UK.
- Yusuf Hamied Department of Chemistry, University of Cambridge, Cambridge, CB2 1EW, UK.
- School of Clinical Medicine, University of Cambridge, Cambridge, CB2 0SP, UK.
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11
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Goh YT, Koh CWQ, Sim DY, Roca X, Goh WSS. METTL4 catalyzes m6Am methylation in U2 snRNA to regulate pre-mRNA splicing. Nucleic Acids Res 2020; 48:9250-9261. [PMID: 32813009 PMCID: PMC7498333 DOI: 10.1093/nar/gkaa684] [Citation(s) in RCA: 53] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Revised: 07/23/2020] [Accepted: 08/04/2020] [Indexed: 01/06/2023] Open
Abstract
N6-methylation of 2′-O-methyladenosine (Am) in RNA occurs in eukaryotic cells to generate N6,2′-O-dimethyladenosine (m6Am). Identification of the methyltransferase responsible for m6Am catalysis has accelerated studies on the function of m6Am in RNA processing. While m6Am is generally found in the first transcribed nucleotide of mRNAs, the modification is also found internally within U2 snRNA. However, the writer required for catalyzing internal m6Am formation had remained elusive. By sequencing transcriptome-wide RNA methylation at single-base-resolution, we identified human METTL4 as the writer that directly methylates Am at U2 snRNA position 30 into m6Am. We found that METTL4 localizes to the nucleus and its conserved methyltransferase catalytic site is required for U2 snRNA methylation. By sequencing human cells with overexpressed Mettl4, we determined METTL4’s in vivo target RNA motif specificity. In the absence of Mettl4 in human cells, U2 snRNA lacks m6Am thereby affecting a subset of splicing events that exhibit specific features such as 3′ splice-site weakness and an increase in exon inclusion. These findings suggest that METTL4 methylation of U2 snRNA regulates splicing of specific pre-mRNA transcripts.
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Affiliation(s)
- Yeek Teck Goh
- Genome Institute of Singapore, 60 Biopolis Street, Singapore 138672, Singapore
| | - Casslynn W Q Koh
- Genome Institute of Singapore, 60 Biopolis Street, Singapore 138672, Singapore
| | - Donald Yuhui Sim
- School of Biological Sciences, Nanyang Technological University, Singapore 637551, Singapore
| | - Xavier Roca
- School of Biological Sciences, Nanyang Technological University, Singapore 637551, Singapore
| | - W S Sho Goh
- Genome Institute of Singapore, 60 Biopolis Street, Singapore 138672, Singapore
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12
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Alharbi AB, Schmitz U, Marshall AD, Vanichkina D, Nagarajah R, Vellozzi M, Wong JJ, Bailey CG, Rasko JE. Ctcf haploinsufficiency mediates intron retention in a tissue-specific manner. RNA Biol 2020; 18:93-103. [PMID: 32816606 PMCID: PMC7834090 DOI: 10.1080/15476286.2020.1796052] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
CTCF is a master regulator of gene transcription and chromatin organisation with occupancy at thousands of DNA target sites genome-wide. While CTCF is essential for cell survival, CTCF haploinsufficiency is associated with tumour development and hypermethylation. Increasing evidence demonstrates CTCF as a key player in several mechanisms regulating alternative splicing (AS), however, the genome-wide impact of Ctcf dosage on AS has not been investigated. We examined the effect of Ctcf haploinsufficiency on gene expression and AS in five tissues from Ctcf hemizygous (Ctcf+/-) mice. Reduced Ctcf levels caused distinct tissue-specific differences in gene expression and AS in all tissues. An increase in intron retention (IR) was observed in Ctcf+/- liver and kidney. In liver, this specifically impacted genes associated with cytoskeletal organisation, splicing and metabolism. Strikingly, most differentially retained introns were short, with a high GC content and enriched in Ctcf binding sites in their proximal upstream genomic region. This study provides new insights into the effects of CTCF haploinsufficiency on organ transcriptomes and the role of CTCF in AS regulation.
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Affiliation(s)
- Adel B Alharbi
- Gene & Stem Cell Therapy Program Centenary Institute, The University of Sydney , Camperdown, Australia.,Computational BioMedicine Laboratory Centenary Institute, The University of Sydney , Camperdown, Australia.,Faculty of Medicine and Health, The University of Sydney , Camperdown, Australia.,Department of Laboratory Medicine, Faculty of Applied Medical Sciences, Umm Al-Qura University , Makkah, Saudi Arabia
| | - Ulf Schmitz
- Gene & Stem Cell Therapy Program Centenary Institute, The University of Sydney , Camperdown, Australia.,Computational BioMedicine Laboratory Centenary Institute, The University of Sydney , Camperdown, Australia.,Faculty of Medicine and Health, The University of Sydney , Camperdown, Australia
| | - Amy D Marshall
- Gene & Stem Cell Therapy Program Centenary Institute, The University of Sydney , Camperdown, Australia
| | - Darya Vanichkina
- Gene & Stem Cell Therapy Program Centenary Institute, The University of Sydney , Camperdown, Australia.,Faculty of Medicine and Health, The University of Sydney , Camperdown, Australia.,Sydney Informatics Hub, University of Sydney , Darlington, Australia
| | - Rajini Nagarajah
- Gene & Stem Cell Therapy Program Centenary Institute, The University of Sydney , Camperdown, Australia
| | - Melissa Vellozzi
- Gene & Stem Cell Therapy Program Centenary Institute, The University of Sydney , Camperdown, Australia.,Computational BioMedicine Laboratory Centenary Institute, The University of Sydney , Camperdown, Australia
| | - Justin Jl Wong
- Faculty of Medicine and Health, The University of Sydney , Camperdown, Australia.,Epigenetics and RNA Biology Program Centenary Institute, The University of Sydney , Camperdown, Australia
| | - Charles G Bailey
- Gene & Stem Cell Therapy Program Centenary Institute, The University of Sydney , Camperdown, Australia.,Faculty of Medicine and Health, The University of Sydney , Camperdown, Australia
| | - John Ej Rasko
- Gene & Stem Cell Therapy Program Centenary Institute, The University of Sydney , Camperdown, Australia.,Faculty of Medicine and Health, The University of Sydney , Camperdown, Australia.,Cell & Molecular Therapies, Royal Prince Alfred Hospital , Camperdown, Australia
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13
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Farina AR, Cappabianca L, Sebastiano M, Zelli V, Guadagni S, Mackay AR. Hypoxia-induced alternative splicing: the 11th Hallmark of Cancer. J Exp Clin Cancer Res 2020; 39:110. [PMID: 32536347 PMCID: PMC7294618 DOI: 10.1186/s13046-020-01616-9] [Citation(s) in RCA: 67] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Accepted: 06/03/2020] [Indexed: 12/16/2022] Open
Abstract
Hypoxia-induced alternative splicing is a potent driving force in tumour pathogenesis and progression. In this review, we update currents concepts of hypoxia-induced alternative splicing and how it influences tumour biology. Following brief descriptions of tumour-associated hypoxia and the pre-mRNA splicing process, we review the many ways hypoxia regulates alternative splicing and how hypoxia-induced alternative splicing impacts each individual hallmark of cancer. Hypoxia-induced alternative splicing integrates chemical and cellular tumour microenvironments, underpins continuous adaptation of the tumour cellular microenvironment responsible for metastatic progression and plays clear roles in oncogene activation and autonomous tumour growth, tumor suppressor inactivation, tumour cell immortalization, angiogenesis, tumour cell evasion of programmed cell death and the anti-tumour immune response, a tumour-promoting inflammatory response, adaptive metabolic re-programming, epithelial to mesenchymal transition, invasion and genetic instability, all of which combine to promote metastatic disease. The impressive number of hypoxia-induced alternative spliced protein isoforms that characterize tumour progression, classifies hypoxia-induced alternative splicing as the 11th hallmark of cancer, and offers a fertile source of potential diagnostic/prognostic markers and therapeutic targets.
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Affiliation(s)
- Antonietta Rosella Farina
- Department of Applied Clinical and Biotechnological Sciences, University of L’Aquila, 67100 L’Aquila, Italy
| | - Lucia Cappabianca
- Department of Applied Clinical and Biotechnological Sciences, University of L’Aquila, 67100 L’Aquila, Italy
| | - Michela Sebastiano
- Department of Applied Clinical and Biotechnological Sciences, University of L’Aquila, 67100 L’Aquila, Italy
| | - Veronica Zelli
- Department of Applied Clinical and Biotechnological Sciences, University of L’Aquila, 67100 L’Aquila, Italy
| | - Stefano Guadagni
- Department of Applied Clinical and Biotechnological Sciences, University of L’Aquila, 67100 L’Aquila, Italy
| | - Andrew Reay Mackay
- Department of Applied Clinical and Biotechnological Sciences, University of L’Aquila, 67100 L’Aquila, Italy
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14
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Qiu R, Zhang J, Xiang X. The splicing-factor Prp40 affects dynein-dynactin function in Aspergillus nidulans. Mol Biol Cell 2020; 31:1289-1301. [PMID: 32267207 PMCID: PMC7353152 DOI: 10.1091/mbc.e20-03-0166] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
The multi-component cytoplasmic dynein transports cellular cargoes with the help of another multi-component complex dynactin, but we do not know enough about factors that may affect the assembly and functions of these proteins. From a genetic screen for mutations affecting early-endosome distribution in Aspergillus nidulans, we identified the prp40AL438* mutation in Prp40A, a homologue of Prp40, an essential RNA-splicing factor in the budding yeast. Prp40A is not essential for splicing, although it associates with the nuclear splicing machinery. The prp40AL438* mutant is much healthier than the ∆prp40A mutant, but both mutants exhibit similar defects in dynein-mediated early-endosome transport and nuclear distribution. In the prp40AL438* mutant, the frequency but not the speed of dynein-mediated early-endosome transport is decreased, which correlates with a decrease in the microtubule plus-end accumulations of dynein and dynactin. Within the dynactin complex, the actin-related protein Arp1 forms a mini-filament. In a pull-down assay, the amount of Arp1 pulled down with its pointed-end protein Arp11 is lowered in the prp40AL438* mutant. In addition, we found from published interactome data that a mammalian Prp40 homologue PRPF40A interacts with Arp1. Thus, Prp40 homologues may regulate the assembly or function of dynein–dynactin and their mechanisms deserve to be further studied.
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Affiliation(s)
- Rongde Qiu
- Department of Biochemistry and Molecular Biology, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD 20814
| | - Jun Zhang
- Department of Biochemistry and Molecular Biology, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD 20814
| | - Xin Xiang
- Department of Biochemistry and Molecular Biology, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD 20814
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