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Tsukiyama T. New insights in ubiquitin-dependent Wnt receptor regulation in tumorigenesis. In Vitro Cell Dev Biol Anim 2024; 60:449-465. [PMID: 38383910 PMCID: PMC11126518 DOI: 10.1007/s11626-024-00855-w] [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: 10/24/2023] [Accepted: 01/17/2024] [Indexed: 02/23/2024]
Abstract
Wnt signaling plays a crucial role in embryonic development and homeostasis maintenance. Delicate and sensitive fine-tuning of Wnt signaling based on the proper timings and positions is required to balance cell proliferation and differentiation and maintain individual health. Therefore, homeostasis is broken by tissue hypoplasia or tumor formation once Wnt signal dysregulation disturbs the balance of cell proliferation. The well-known regulatory mechanism of Wnt signaling is the molecular reaction associated with the cytoplasmic accumulation of effector β-catenin. In addition to β-catenin, most Wnt effector proteins are also regulated by ubiquitin-dependent modification, both qualitatively and quantitatively. This review will explain the regulation of the whole Wnt signal in four regulatory phases, as well as the different ubiquitin ligases and the function of deubiquitinating enzymes in each phase. Along with the recent results, the mechanism by which RNF43 negatively regulates the surface expression of Wnt receptors, which has recently been well understood, will be detailed. Many RNF43 mutations have been identified in pancreatic and gastrointestinal cancers and examined for their functional alteration in Wnt signaling. Several mutations facilitate or activate the Wnt signal, reversing the RNF43 tumor suppressor function into an oncogene. RNF43 may simultaneously play different roles in classical multistep tumorigenesis, as both wild-type and mutant RNF43 suppress the p53 pathway. We hope that the knowledge obtained from further research in RNF43 will be applied to cancer treatment in the future despite the fully unclear function of RNF43.
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Affiliation(s)
- Tadasuke Tsukiyama
- Department of Biochemistry, Graduate School of Medicine, Hokkaido University, 15NW7, Kita-Ku, Sapporo, Hokkaido, 060-8638, Japan.
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2
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Hsu SH, Tsai YL, Wang YT, Shen CH, Hung YH, Chen LT, Hung WC. RNF43 Inactivation Enhances the B-RAF/MEK Signaling and Creates a Combinatory Therapeutic Target in Cancer Cells. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024; 11:e2304820. [PMID: 38225722 DOI: 10.1002/advs.202304820] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2023] [Revised: 12/31/2023] [Indexed: 01/17/2024]
Abstract
RING finger 43 (RNF43), a RING-type E3 ubiquitin ligase, is a key regulator of WNT signaling and is mutated in 6-10% of pancreatic tumors. However, RNF43-mediated effects remain unclear, as only a few in vivo substrates of RNF43 are identified. Here, it is found that RNF43-mutated pancreatic cancer cells exhibit elevated B-RAF/MEK activity and are highly sensitive to MEK inhibitors. The depletion of RNF43 in normal pancreatic ductal cells also enhances MEK activation, suggesting that it is a physiologically regulated process. It is confirmed that RNF43 ubiquitinates B-RAF at K499 to promote proteasome-dependent degradation, resulting in reduced MEK activity and proliferative ability in cancer cells. In addition, phosphorylation of B-RAF at T491 suppresses B-RAF ubiquitination by decreasing the interaction between RNF43 and B-RAF. Mutations at K499 in B-RAF are identified in various cancer types. MEK and WNT inhibitors synergistically suppress the growth of RNF43-mutated pancreatic cancer cells in vitro and in vivo. Collectively, the research reveals a novel mechanism by which RNF43 inhibits B-RAF/MEK signaling to suppress tumor growth and provide a new strategy for the treatment of RNF43-inactivated pancreatic cancer.
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Affiliation(s)
- Shih-Han Hsu
- National Institute of Cancer Research, National Health Research Institutes, Tainan, 704, Taiwan
| | - Ya-Li Tsai
- National Institute of Cancer Research, National Health Research Institutes, Tainan, 704, Taiwan
| | - Yeng-Tseng Wang
- Department of Biochemistry, College of Medicine, Kaohsiung Medical University, Kaohsiung, 807, Taiwan
| | - Che-Hung Shen
- National Institute of Cancer Research, National Health Research Institutes, Tainan, 704, Taiwan
| | - Yu-Hsuan Hung
- Department of Medical Research, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, 807, Taiwan
| | - Li-Tzong Chen
- National Institute of Cancer Research, National Health Research Institutes, Tainan, 704, Taiwan
- Division of Gastroenterology, Department of Internal Medicine, Kaohsiung Medical University Hospital, Kaohsiung, 804, Taiwan
- Faculty of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, 807, Taiwan
| | - Wen-Chun Hung
- National Institute of Cancer Research, National Health Research Institutes, Tainan, 704, Taiwan
- Department of Pharmacy, College of Pharmacy, Kaohsiung Medical University Hospital, Kaohsiung, 807, Taiwan
- Department of Biological Science and Technology, National Yang Ming Chiao Tong University, Hsinchu, 300, Taiwan
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3
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Dong L, Li W, Lin T, Liu B, Hong Y, Zhang X, Li X. PSF functions as a repressor of hypoxia-induced angiogenesis by promoting mitochondrial function. Cell Commun Signal 2021; 19:14. [PMID: 33573690 PMCID: PMC7879653 DOI: 10.1186/s12964-020-00684-w] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2020] [Accepted: 11/10/2020] [Indexed: 01/15/2023] Open
Abstract
BACKGROUND Abnormal neovascularization is the most common cause of blindness, and hypoxia alters tissue metabolism, function, and morphology. HIF-1α, the transcriptional activator of VEGF, has intricate mechanisms of nuclear translocation and activation, but its signal termination mechanisms remain unclear. METHODS We investigated the role of polypyrimidine tract-binding protein-associated splicing factor (PSF) in cellular energy production, migration, and proliferation by targeting HIF-1α in vivo and in vitro PSF plasmids were transfected with liposome 2000 transfection reagent. Young C57/BL6J mice were kept in a hyperoxia environment, followed by indoor air, resulting in oxygen-induced retinopathy. Oxygen-induced retinopathy (OIR) animals were randomly divided into three groups: OIR group, OIR + vector group (OIR cubs treated with rAAV vector) and OIR + PSF group (OIR cubs treated with rAAV-PSF). Age-matched C57/BL6J mice were used as controls and exposed to constant normoxic conditions. The animals were executed and their pupils were subjected to subsequent experiments. The metabolic spectrum was analyzed by Seahorse XFe96 flux analyzer, and OCR and extracellular acidification rate were quantified at the same time. RESULTS PSF ameliorated retinal neovascularization and corrected abnormal VEGF expression in mice with oxygen-induced retinopathy and reduced intra-retinal neovascularization in Vldlr - / - mice. PSF reprogrammed mitochondrial bioenergetics and inhibited the transition of endothelial cells after hypoxia, suggesting its involvement in pathological angiogenesis.Ectopic PSF expression inhibited hypoxia-induced HIF-1α activation in the nucleus by recruiting Hakai to the PSF/HIF-1α complex, causing HIF-1α inhibition. PSF knockdown increased hypoxia-stimulated HIF-1α reactions. These hypoxia-dependent processes may play a vital role in cell metabolism, migration, and proliferation. Thus, PSF is a potential treatment target in neovascularization-associated ophthalmopathy. CONCLUSION This is the first study showing that PSF inhibits HIF-1α via recruitment of Hakai, modulates mitochondrial oxidation and glycolysis, and downregulates VEGF expression under hypoxia. We propose a new HIF-1 α/Hakai regulatory mechanism that may play a vital role in the pathogenesis of neovascularization in ophthalmopathy. PSF-Hakai-HIF-1α signaling pathway under hypoxia condition. Schematic diagram showing that the PSF-Hakai-HIF-1α signaling pathway. Under hypoxia condition, PSF-Hakai complex regulate HIF-1α signaling, thus inhibiting downstream target gene VEGF, cell metabolism and angiogenesis eventually. Video Abstract: Detailed information of Materials and Methods.
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Affiliation(s)
- Lijie Dong
- Tianjin Key Laboratory of Retinal Functions and Diseases, Tianjin, People’s Republic of China
- Tianjin International Joint Research and Development Centre of Ophthalmology and Vision Science, Tianjin, People’s Republic of China
- Eye Institute and School of Optometry, Tianjin Medical University Eye Hospital, 251 Fukang Road, Nankai, Tianjin, 300384 People’s Republic of China
| | - Wenbo Li
- Tianjin Key Laboratory of Retinal Functions and Diseases, Tianjin, People’s Republic of China
- Tianjin International Joint Research and Development Centre of Ophthalmology and Vision Science, Tianjin, People’s Republic of China
- Eye Institute and School of Optometry, Tianjin Medical University Eye Hospital, 251 Fukang Road, Nankai, Tianjin, 300384 People’s Republic of China
| | - Tingting Lin
- Tianjin Key Laboratory of Retinal Functions and Diseases, Tianjin, People’s Republic of China
- Tianjin International Joint Research and Development Centre of Ophthalmology and Vision Science, Tianjin, People’s Republic of China
- Eye Institute and School of Optometry, Tianjin Medical University Eye Hospital, 251 Fukang Road, Nankai, Tianjin, 300384 People’s Republic of China
| | - Boshi Liu
- Tianjin Key Laboratory of Retinal Functions and Diseases, Tianjin, People’s Republic of China
- Tianjin International Joint Research and Development Centre of Ophthalmology and Vision Science, Tianjin, People’s Republic of China
- Eye Institute and School of Optometry, Tianjin Medical University Eye Hospital, 251 Fukang Road, Nankai, Tianjin, 300384 People’s Republic of China
| | - Yaru Hong
- Tianjin Key Laboratory of Retinal Functions and Diseases, Tianjin, People’s Republic of China
- Tianjin International Joint Research and Development Centre of Ophthalmology and Vision Science, Tianjin, People’s Republic of China
- Eye Institute and School of Optometry, Tianjin Medical University Eye Hospital, 251 Fukang Road, Nankai, Tianjin, 300384 People’s Republic of China
| | - Xiaomin Zhang
- Tianjin Key Laboratory of Retinal Functions and Diseases, Tianjin, People’s Republic of China
- Tianjin International Joint Research and Development Centre of Ophthalmology and Vision Science, Tianjin, People’s Republic of China
- Eye Institute and School of Optometry, Tianjin Medical University Eye Hospital, 251 Fukang Road, Nankai, Tianjin, 300384 People’s Republic of China
| | - Xiaorong Li
- Tianjin Key Laboratory of Retinal Functions and Diseases, Tianjin, People’s Republic of China
- Tianjin International Joint Research and Development Centre of Ophthalmology and Vision Science, Tianjin, People’s Republic of China
- Eye Institute and School of Optometry, Tianjin Medical University Eye Hospital, 251 Fukang Road, Nankai, Tianjin, 300384 People’s Republic of China
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Lerksuthirat T, Wikiniyadhanee R, Stitchantrakul W, Chitphuk S, Stansook N, Pipatpanyanugoon N, Jirawatnotai S, Dejsuphong D. A DNA repair player, ring finger protein 43, relieves etoposide-induced topoisomerase II poisoning. Genes Cells 2020; 25:718-729. [PMID: 32939879 DOI: 10.1111/gtc.12808] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Revised: 08/15/2020] [Accepted: 09/06/2020] [Indexed: 12/25/2022]
Abstract
Ring finger protein 43 (RNF43) is an E3 ubiquitin ligase which is well-known for its role in negative regulation of the Wnt-signaling pathway. However, the function in DNA double-strand break repairs has not been investigated. In this study, we used a lymphoblast cell line, DT40, and mouse embryonic fibroblast as cellular models to study DNA double-strand break (DSB) repairs. For this purpose, we created RNF43 knockout, RNF43-/- DT40 cell line to investigate DSB repairs. We found that deletion of RNF43 does not interfere with cell proliferation. However, after exposure to various types of DNA-damaging agents, RNF43-/- cells become more sensitive to topoisomerase II inhibitors, etoposide, and ICRF193, than wild type cells. Our results also showed that depletion of RNF43 results in apoptosis upon etoposide-mediated DNA damage. The delay in resolution of γH2AX and 53BP1 foci formation after etoposide treatment, as well as epistasis analysis with DNAPKcs, suggested that RNF43 might participate in DNA repair of etoposide-induced DSB via non-homologous end joining. Disturbed γH2AX foci formation in MEFs following pulse etoposide treatment supported the notion that RNF43 also functions DNA repair in mammalian cells. These findings propose two possible functions of RNF43, either participating in NHEJ or removing the blockage of 5' topo II adducts from DSB ends.
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Affiliation(s)
- Tassanee Lerksuthirat
- Research Center, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
| | - Rakkreat Wikiniyadhanee
- Section for Translational Medicine, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
| | - Wasana Stitchantrakul
- Research Center, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
| | - Sermsiri Chitphuk
- Research Center, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
| | - Nauljun Stansook
- Division of Radiotherapy and Oncology, Department of Diagnostic and Therapeutic Radiology, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
| | - Nut Pipatpanyanugoon
- Siriraj Center of Research for Excellence (SiCORE) for Systems Pharmacology, Department of Pharmacology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - Siwanon Jirawatnotai
- Siriraj Center of Research for Excellence (SiCORE) for Systems Pharmacology, Department of Pharmacology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - Donniphat Dejsuphong
- Section for Translational Medicine, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
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5
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Abstract
RNF43 (E3 ubiquitin-protein ligase RNF43 or RING-type E3 ubiquitin transferase RNF43) functions as a tumor suppressor, by exerting a predominant negative feedback mechanism in the Wnt/β-catenin signaling pathway. RNF43 inhibits Wnt/beta-catenin signaling by ubiquitinating Frizzled receptor and targeting it to the lysosomal pathway for degradation. Loss of function of RNF43 results in decrease/lack of degradation of Frizzled with enhancement of Wnt/β-catenin signaling pathway. Mutations of RNF43 have been reported in different cancers. We describe the structure of RNF43, its function and most frequent mutations in different cancers.
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Affiliation(s)
- Stefano Serra
- Department of Anatomic Pathology, Laboratory Medicine Program, University Health Network and University of Toronto, Toronto, Canada
| | - Runjan Chetty
- Department of Anatomic Pathology, Laboratory Medicine Program, University Health Network and University of Toronto, Toronto, Canada
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6
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NEAT1 scaffolds RNA-binding proteins and the Microprocessor to globally enhance pri-miRNA processing. Nat Struct Mol Biol 2017; 24:816-824. [PMID: 28846091 PMCID: PMC5766049 DOI: 10.1038/nsmb.3455] [Citation(s) in RCA: 146] [Impact Index Per Article: 20.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2016] [Accepted: 08/01/2017] [Indexed: 12/27/2022]
Abstract
MicroRNA biogenesis is known to be modulated by a variety of RNA binding proteins (RBPs), but in most cases, individual RBPs appear to influence the processing of a small subset of target miRNAs. We herein report that the RNA binding NONO/PSF heterodimer binds a large number of expressed pri-miRNAs in HeLa cells to globally enhance pri-miRNA processing by the Drosha/DGCR8 Microprocessor. Because NONO/PSF are key components of paraspeckles organized by the lncRNA NEAT1, we further demonstrate that NEAT1 also has a profound effect on global pri-miRNA processing. Mechanistic dissection reveals that NEAT1 broadly interacts with NONO/PSF as well as many other RBPs, and that multiple RNA segments in NEAT1, including a “pseudo pri-miRNA” near its 3′ end, help attract the Microprocessor. These findings suggest a bird nest model for a large non-coding RNA to orchestrate efficient processing of almost an entire class of small non-coding RNAs in the nucleus.
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7
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Loregger A, Grandl M, Mejías-Luque R, Allgäuer M, Degenhart K, Haselmann V, Oikonomou C, Hatzis P, Janssen KP, Nitsche U, Gradl D, van den Broek O, Destree O, Ulm K, Neumaier M, Kalali B, Jung A, Varela I, Schmid RM, Rad R, Busch DH, Gerhard M. The E3 ligase RNF43 inhibits Wnt signaling downstream of mutated β-catenin by sequestering TCF4 to the nuclear membrane. Sci Signal 2015; 8:ra90. [PMID: 26350900 DOI: 10.1126/scisignal.aac6757] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Given its fundamental role in development and cancer, the Wnt-β-catenin signaling pathway is tightly controlled at multiple levels. RING finger protein 43 (RNF43) is an E3 ubiquitin ligase originally found in stem cells and proposed to inhibit Wnt signaling by interacting with the Wnt receptors of the Frizzled family. We detected endogenous RNF43 in the nucleus of human intestinal crypt and colon cancer cells. We found that RNF43 physically interacted with T cell factor 4 (TCF4) in cells and tethered TCF4 to the nuclear membrane, thus silencing TCF4 transcriptional activity even in the presence of constitutively active mutants of β-catenin. This inhibitory mechanism was disrupted by the expression of RNF43 bearing mutations found in human gastrointestinal tumors, and transactivation of the Wnt pathway was observed in various cells and in Xenopus embryos when the RING domain of RNF43 was mutated. Our findings indicate that RNF43 inhibits the Wnt pathway downstream of oncogenic mutations that activate the pathway. Mimicking or enhancing this inhibitory activity of RNF43 may be useful to treat cancers arising from aberrant activation of the Wnt pathway.
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Affiliation(s)
- Anke Loregger
- Institut für Medizinische Mikrobiologie, Immunologie und Hygiene, Technische Universität München, Munich 81675, Germany
| | - Martina Grandl
- Institut für Medizinische Mikrobiologie, Immunologie und Hygiene, Technische Universität München, Munich 81675, Germany
| | - Raquel Mejías-Luque
- Institut für Medizinische Mikrobiologie, Immunologie und Hygiene, Technische Universität München, Munich 81675, Germany
| | - Michael Allgäuer
- Institut für Medizinische Mikrobiologie, Immunologie und Hygiene, Technische Universität München, Munich 81675, Germany. Medical Department II, Technische Universität München, Munich 81675, Germany
| | - Kathrin Degenhart
- Institut für Medizinische Mikrobiologie, Immunologie und Hygiene, Technische Universität München, Munich 81675, Germany
| | - Verena Haselmann
- Institute for Clinical Chemistry, University Medical Centre Mannheim, Mannheim 68167, Germany
| | - Christina Oikonomou
- Division of Molecular Biology and Genetics, Biomedical Sciences Research Center "Alexander Fleming," Vari 16672, Greece
| | - Pantelis Hatzis
- Division of Molecular Biology and Genetics, Biomedical Sciences Research Center "Alexander Fleming," Vari 16672, Greece
| | - Klaus-Peter Janssen
- Department of Surgery, Technische Universität München, Munich 81675, Germany
| | - Ulrich Nitsche
- Department of Surgery, Technische Universität München, Munich 81675, Germany
| | - Dietmar Gradl
- Zoologisches Institut II, Karlsruhe Institute of Technology, Karlsruhe 76131, Germany
| | | | | | - Kurt Ulm
- Institute of Medical Statistics and Epidemiology, Technische Universität München, Munich 81675, Germany
| | - Michael Neumaier
- Institute for Clinical Chemistry, University Medical Centre Mannheim, Mannheim 68167, Germany
| | - Behnam Kalali
- Institut für Medizinische Mikrobiologie, Immunologie und Hygiene, Technische Universität München, Munich 81675, Germany
| | - Andreas Jung
- Institute of Pathology, University of Munich, Munich 80337, Germany
| | - Ignacio Varela
- Instituto de Biomedicina y Biotecnología de Cantabria, Santander 39011, Spain
| | - Roland M Schmid
- Medical Department II, Technische Universität München, Munich 81675, Germany
| | - Roland Rad
- Medical Department II, Technische Universität München, Munich 81675, Germany
| | - Dirk H Busch
- Institut für Medizinische Mikrobiologie, Immunologie und Hygiene, Technische Universität München, Munich 81675, Germany
| | - Markus Gerhard
- Institut für Medizinische Mikrobiologie, Immunologie und Hygiene, Technische Universität München, Munich 81675, Germany.
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Lee M, Sadowska A, Bekere I, Ho D, Gully BS, Lu Y, Iyer KS, Trewhella J, Fox AH, Bond CS. The structure of human SFPQ reveals a coiled-coil mediated polymer essential for functional aggregation in gene regulation. Nucleic Acids Res 2015; 43:3826-40. [PMID: 25765647 PMCID: PMC4402515 DOI: 10.1093/nar/gkv156] [Citation(s) in RCA: 101] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Accepted: 02/18/2015] [Indexed: 12/14/2022] Open
Abstract
SFPQ, (a.k.a. PSF), is a human tumor suppressor protein that regulates many important functions in the cell nucleus including coordination of long non-coding RNA molecules into nuclear bodies. Here we describe the first crystal structures of Splicing Factor Proline and Glutamine Rich (SFPQ), revealing structural similarity to the related PSPC1/NONO heterodimer and a strikingly extended structure (over 265 Å long) formed by an unusual anti-parallel coiled-coil that results in an infinite linear polymer of SFPQ dimers within the crystals. Small-angle X-ray scattering and transmission electron microscopy experiments show that polymerization is reversible in solution and can be templated by DNA. We demonstrate that the ability to polymerize is essential for the cellular functions of SFPQ: disruptive mutation of the coiled-coil interaction motif results in SFPQ mislocalization, reduced formation of nuclear bodies, abrogated molecular interactions and deficient transcriptional regulation. The coiled-coil interaction motif thus provides a molecular explanation for the functional aggregation of SFPQ that directs its role in regulating many aspects of cellular nucleic acid metabolism.
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Affiliation(s)
- Mihwa Lee
- School of Chemistry and Biochemistry, University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009, Australia
| | - Agata Sadowska
- School of Chemistry and Biochemistry, University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009, Australia Harry Perkins Institute for Medical Research, QEII Medical Centre, Nedlands and Centre for Medical Research, The University of Western Australia, Crawley, Western Australia 6009, Australia
| | - Indra Bekere
- School of Chemistry and Biochemistry, University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009, Australia
| | - Diwei Ho
- School of Chemistry and Biochemistry, University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009, Australia
| | - Benjamin S Gully
- School of Chemistry and Biochemistry, University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009, Australia
| | - Yanling Lu
- School of Molecular Bioscience, University of Sydney, Sydney, NSW 2006, Australia
| | - K Swaminathan Iyer
- School of Chemistry and Biochemistry, University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009, Australia
| | - Jill Trewhella
- School of Molecular Bioscience, University of Sydney, Sydney, NSW 2006, Australia
| | - Archa H Fox
- Harry Perkins Institute for Medical Research, QEII Medical Centre, Nedlands and Centre for Medical Research, The University of Western Australia, Crawley, Western Australia 6009, Australia
| | - Charles S Bond
- School of Chemistry and Biochemistry, University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009, Australia
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9
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Dong L, Nian H, Shao Y, Zhang Y, Li Q, Yi Y, Tian F, Li W, Zhang H, Zhang X, Wang F, Li X. PTB-associated splicing factor inhibits IGF-1-induced VEGF upregulation in a mouse model of oxygen-induced retinopathy. Cell Tissue Res 2015; 360:233-43. [PMID: 25638408 DOI: 10.1007/s00441-014-2104-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2014] [Accepted: 12/21/2014] [Indexed: 12/25/2022]
Abstract
Pathological retinal neovascularization, including retinopathy of prematurity and age-related macular degeneration, is the most common cause of blindness worldwide. Insulin-like growth factor-1 (IGF-1) has a direct mitogenic effect on endothelial cells, which is the basis of angiogenesis. Vascular endothelial growth factor (VEGF) activation in response to IGF-1 is well documented; however, the molecular mechanisms responsible for the termination of IGF-1 signaling are still not completely elucidated. Here, we show that the polypyrimidine tract-binding protein-associated splicing factor (PSF) is a potential negative regulator of VEGF expression induced by IGF stimulation. Functional analysis demonstrated that ectopic expression of PSF inhibits IGF-1-stimulated transcriptional activation and mRNA expression of the VEGF gene, whereas knockdown of PSF increased IGF-1-stimulated responses. PSF recruited Hakai to the VEGF transcription complex, resulting in inhibition of IGF-1-mediated transcription. Transfection with Hakai siRNA reversed the PSF-mediated transcriptional repression of VEGF gene transcription. In summary, these results show that PSF can repress the transcriptional activation of VEGF stimulated by IGF-1 via recruitment of the Hakai complex and delineate a novel regulatory mechanism of IGF-1/VEGF signaling that may have implications in the pathogenesis of neovascularization in ocular diseases.
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Affiliation(s)
- Lijie Dong
- Tianjin Medical University Eye Hospital, Tianjin, People's Republic of China,
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10
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Cho S, Moon H, Loh TJ, Oh HK, Williams DR, Liao DJ, Zhou J, Green MR, Zheng X, Shen H. PSF contacts exon 7 of SMN2 pre-mRNA to promote exon 7 inclusion. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2014; 1839:517-25. [PMID: 24632473 DOI: 10.1016/j.bbagrm.2014.03.003] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 12/07/2013] [Revised: 03/03/2014] [Accepted: 03/06/2014] [Indexed: 12/23/2022]
Abstract
Spinal muscular atrophy (SMA) is an autosomal recessive genetic disease and a leading cause of infant mortality. Deletions or mutations of SMN1 cause SMA, a gene that encodes a SMN protein. SMN is important for the assembly of Sm proteins onto UsnRNA to UsnRNP. SMN has also been suggested to direct axonal transport of β-actin mRNA in neurons. Humans contain a second SMN gene called SMN2 thus SMA patients produce some SMN but not with sufficient levels. The majority of SMN2 mRNA does not include exon 7. Here we show that increased expression of PSF promotes inclusion of exon 7 in the SMN2 whereas reduced expression of PSF promotes exon 7 skipping. In addition, we present evidence showing that PSF interacts with the GAAGGA enhancer in exon 7. We also demonstrate that a mutation in this enhancer abolishes the effects of PSF on exon 7 splicing. Furthermore we show that the RNA target sequences of PSF and tra2β in exon 7 are partially overlapped. These results lead us to conclude that PSF interacts with an enhancer in exon 7 to promote exon 7 splicing of SMN2 pre-mRNA.
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Affiliation(s)
- Sunghee Cho
- School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju 500-712, Republic of Korea
| | - Heegyum Moon
- School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju 500-712, Republic of Korea
| | - Tiing Jen Loh
- School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju 500-712, Republic of Korea
| | - Hyun Kyung Oh
- School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju 500-712, Republic of Korea
| | - Darren Reese Williams
- School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju 500-712, Republic of Korea
| | - D Joshua Liao
- Hormel Institute, University of Minnesota, Austin, MN, USA
| | | | - Michael R Green
- Howard Hughes Medical Institute and Programs in Gene Function and Expression and Molecular Medicine, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Xuexiu Zheng
- School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju 500-712, Republic of Korea
| | - Haihong Shen
- School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju 500-712, Republic of Korea.
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11
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Xing C, Zhou W, Ding S, Xie H, Zhang W, Yang Z, Wei B, Chen K, Su R, Cheng J, Zheng S, Zhou L. Reversing effect of ring finger protein 43 inhibition on malignant phenotypes of human hepatocellular carcinoma. Mol Cancer Ther 2012; 12:94-103. [PMID: 23136185 DOI: 10.1158/1535-7163.mct-12-0672] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
It has been shown that Ring finger protein 43 (RNF43) is overexpressed in colorectal cancer and mediates cancer cell proliferation; however, its role in hepatocellular carcinoma (HCC) remains unknown. In this study, we found that RNF43 was frequently overexpressed in HCCs, and this overexpression was correlated with positive vascular invasion, poor tumor differentiation, and advanced tumor stage. Functional studies showed that knockdown of RNF43 could induce apoptosis and inhibit proliferation, invasion, colony formation, and xenograft growth of HCCs. Microarray-based gene profiling showed a total of 229 genes differentially expressed after RNF43 knockdown, many of which are involved in oncogenic processes such as cell proliferation, cell adhesion, cell motility, cell death, DNA repair, and so on. These results suggest that RNF43 is involved in tumorigenesis and progression of HCCs and that antagonism of RNF43 may be beneficial for HCC treatment.
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Affiliation(s)
- Chunyang Xing
- Key Lab of Combined Multi-organ Transplantation, Ministry of Public Health, Hangzhou, Zhejiang, China
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Dougherty JD, Fomchenko EI, Akuffo AA, Schmidt E, Helmy KY, Bazzoli E, Brennan CW, Holland EC, Milosevic A. Candidate pathways for promoting differentiation or quiescence of oligodendrocyte progenitor-like cells in glioma. Cancer Res 2012; 72:4856-68. [PMID: 22865458 DOI: 10.1158/0008-5472.can-11-2632] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Platelet-derived growth factor receptor alpha-positive oligodendrocyte progenitor cells (OPC) located within the mature central nervous system may remain quiescent, proliferate, or differentiate into oligodendrocytes. Human glioblastoma multiforme tumors often contain rapidly proliferating oligodendrocyte lineage transcription factor 2 (Olig2)-positive cells that resemble OPCs. In this study, we sought to identify candidate pathways that promote OPC differentiation or quiescence rather than proliferation. Gene expression profiling conducted in both normal murine OPCs and highly proliferative Olig2-positive glioma cells identified all the transcripts associated with the highly proliferative state of these cells and showed that among the various cell types found within the brain, Olig2-positive tumor cells are most similar to OPCs. We then subtracted OPC transcripts found in tumor samples from those found in normal brain samples and identified 28 OPC transcripts as candidates for promoting differentiation or quiescence. Systematic analysis of human glioma data revealed that these genes have similar expression profiles in human tumors and were significantly enriched in genomic deletions, suggesting an antiproliferative role. Treatment of primary murine glioblastoma cells with agonists of one candidate gene, Gpr17, resulted in a decreased number of neurospheres. Together, our findings show that comparison of the molecular phenotype of progenitor cells in tumors to the equivalent cells in the normal brain represents a novel approach for the identification of targeted therapies.
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Affiliation(s)
- Joseph D Dougherty
- Department of Genetics and Psychiatry, Washington University, St. Louis, Missouri, USA
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Figueroa A, Fujita Y, Gorospe M. Hacking RNA: Hakai promotes tumorigenesis by enhancing the RNA-binding function of PSF. Cell Cycle 2009; 8:3648-51. [PMID: 19855157 DOI: 10.4161/cc.8.22.9909] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Hakai, an E3 ubiquitin ligase for the E-cadherin complex, plays a crucial role in lowering cell-cell contacts in epithelial cells, a hallmark feature of tumor progression. Recently, Hakai was also found to interact with PSF (PTB-associated splicing factor). While PSF can function as a DNA-binding protein with a tumor suppressive function, its association with Hakai promotes PSF's RNA-binding ability and post-transcriptional influence on target mRNAs. Hakai overexpression enhanced the binding of PSF to mRNAs encoding cancer-related proteins, while knockdown of Hakai reduced the RNA-binding ability of PSF. Furthermore, the knockdown of PSF suppressed Hakai-induced cell proliferation. Thus, Hakai can affect the oncogenic phenotype both by altering E-cadherin-based intercellular adhesions and by increasing PSF's ability to bind RNAs that promote cancer-related gene expression.
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Affiliation(s)
- Angélica Figueroa
- Instituto de Investigación Biomédica A Coruña (INIBIC), Complejo Hospitalario Universitario A Coruña, A Coruña, Spain.
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