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Chen Z, Jin P, Chen Z, Ye F, Ren Z, Ji T, Li R, Yu L. The expression of circ_0090049 in hepatocellular carcinoma and the molecular regulation mechanism of other biological functions. Anticancer Drugs 2022; 33:48-60. [PMID: 34620742 DOI: 10.1097/cad.0000000000001100] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Hepatocellular carcinoma (HCC) is one of the most common malignant tumors in liver cancer. Circular RNA_0090049 (circ_0090049) has been shown to be involved in the advance of HCC. However, the interaction between circ_0090049 and microRNA (miRNA) in HCC has not been studied. Quantitative real-time PCR was used to detect the expression of related genes. Through detection of cell proliferation, migration, invasion, and rate of tumor sphere formation, the capping experiment was carried out to verify the regulatory relationship between miRNA and circ_0090049 or circ_0090049 and ubiquitin-conjugating enzyme E2 T (UBE2T). The expression of related proteins was detected by Western blotting. The interaction of miRNA with circ_0090049 or UBE2T was notarized by Dual-luciferase reporter assay. Xenotransplantation experiments confirmed the function of circ_0090049 in vivo. Circ_0090049 and UBE2T were upregulated in liver cancer. Silencing circ_0090049 reduced the proliferation, migration, invasion, and tumor spheroid formation rate of Huh7 and HCCLM3 cells. MiR-605-5p and miR-548c-3p were identified as targets of circ_0090049, and UBE2T was the target of miR-605-5p and miR-548c-3p. Anti-miR-605-5p, anti-miR-548c-3p or UBE2T overexpression restored the inhibitory effect of circ_0090049 knockdown on HCC cells. Animal experiments confirmed the antitumor effect of silence circ_0090049. Circ_0090049 regulates the expression of UBE2T by regulating miR-605-5p or miR-548c-3p, thereby promoting the development of HCC cells.
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Affiliation(s)
| | | | - Zhen Chen
- General Surgery, Ruian People's Hospital, Ruian City, Zhejiang Province, China
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Liu J, Liao W, Nie B, Zhang J, Xu W. OsUEV1B, an Ubc enzyme variant protein, is required for phosphate homeostasis in rice. Plant J 2021; 106:706-719. [PMID: 33570751 DOI: 10.1111/tpj.15193] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Revised: 02/03/2021] [Accepted: 02/08/2021] [Indexed: 06/12/2023]
Abstract
Phosphorus is a crucial macronutrient for plant growth and development. The mechanisms for maintaining inorganic phosphate (Pi) homeostasis in rice are not well understood. The ubiquitin-conjugating enzyme variant protein OsUEV1B was previously found to interact with OsUbc13 and mediate lysine63-linked polyubiquitination. In the present study, we found OsUEV1B was specifically inhibited by Pi deficiency, and was localized in the nucleus and cytoplasm. Both osuev1b mutant and OsUEV1B-RNA interference (RNAi) lines displayed serious symptoms of toxicity due to Pi overaccumulation. Some Pi starvation inducible and phosphate transporter genes were upregulated in osuev1b mutant and OsUEV1B-RNAi plants in association with enhanced Pi acquisition, and representative Pi starvation responses, including stimulation of acid phosphatase activity and root hair growth, were also activated in the presence of sufficient Pi. A yeast two-hybrid screen revealed an interaction between OsUEV1B and OsVDAC1, which was confirmed by bimolecular fluorescence complementation and firefly split-luciferase complementation assays. OsVDAC1 encoded a voltage-dependent anion channel protein localized in the mitochondria, and OsUbc13 was shown to interact with OsVDAC1 via yeast two-hybrid and bimolecular fluorescence complementation assays. Under sufficient Pi conditions, similar to osuev1b, a mutation in OsVDAC1 resulted in significantly greater Pi concentrations in the roots and second leaves, improved acid phosphatase activity, and enhanced expression of the Pi starvation inducible and phosphate transporter genes compared with wild-type DongJin, whereas overexpression of OsVDAC1 had the opposite effects. OsUEV1B or OsVDAC1 knockout reduced the mitochondrial membrane potential and adenosine triphosphate levels. Moreover, overexpression of OsVDAC1 in osuev1b partially restored its high Pi concentration to a level between those of osuev1b and DongJin. Our results indicate that OsUEV1B is required for rice phosphate homeostasis.
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Affiliation(s)
- Jianping Liu
- Center for Plant Water-use and Nutrition Regulation and College of Life Sciences, Joint International Research Laboratory of Water and Nutrient in Crop, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Wencheng Liao
- Center for Plant Water-use and Nutrition Regulation and College of Life Sciences, Joint International Research Laboratory of Water and Nutrient in Crop, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Bo Nie
- Center for Plant Water-use and Nutrition Regulation and College of Life Sciences, Joint International Research Laboratory of Water and Nutrient in Crop, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Jianhua Zhang
- College of Agriculture, Yangzhou University, Yangzhou, China
- Department of Biology, Hong Kong Baptist University, Hong Kong, China
| | - Weifeng Xu
- Center for Plant Water-use and Nutrition Regulation and College of Life Sciences, Joint International Research Laboratory of Water and Nutrient in Crop, Fujian Agriculture and Forestry University, Fuzhou, China
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3
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Abstract
Besides ubiquitin (Ub), humans have a set of ubiquitin-like proteins (UBLs) that can also covalently modify target proteins. To date, less is known about UBLs than Ub and even less is known about the UBL called ubiquitin-fold modifier 1 (UFM1). Currently, our understanding of protein modification by UFM1 (UFMylation) is like a jigsaw puzzle with many missing pieces, and in some cases it is not even clear whether these pieces of data are in the right place. Here we review the current data on UFM1 from structural biology to biochemistry and cell biology. We believe that the physiological significance of protein modification by UFM1 is currently underestimated and there is more to it than meets the eye.
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Affiliation(s)
| | | | - Reuven Wiener
- Department of Biochemistry and Molecular Biology, The Institute for Medical Research Israel-Canada, Hebrew University-Hadassah Medical School, Jerusalem 91120, Israel; (S.B.); (M.K.)
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Wang S, Li Q, Zhao L, Fu S, Qin L, Wei Y, Fu YB, Wang H. Arabidopsis UBC22, an E2 able to catalyze lysine-11 specific ubiquitin linkage formation, has multiple functions in plant growth and immunity. Plant Sci 2020; 297:110520. [PMID: 32563459 DOI: 10.1016/j.plantsci.2020.110520] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2020] [Revised: 04/15/2020] [Accepted: 05/03/2020] [Indexed: 05/03/2023]
Abstract
Protein ubiquitination is critical for various biological processes in eukaryotes. A ubiquitin (Ub) chain can be linked through one of the seven lysine (K) residues or the N-terminus methionine of the Ub, and the Ub-conjugating enzymes called E2s play a critical role in determining the linkage specificity of Ub chains. Further, while K48-linked polyubiquitin chain is important for protein degradation, much less is known about the functions of other types of polyubiquitin chains in plants. We showed previously that UBC22 is unique in its ability to catalyze K11-dependent Ub dimer formation in vitro and ubc22 knockout mutants had defects in megasporogenesis. In this study, further analyses of the Arabidopsis ubc22 mutants revealed four subtypes of plants based on the phenotypic changes in vegetative growth. These four subtypes appeared consistently in the plants of three independent ubc22 mutants. Transcriptomic analysis showed that transcript levels of genes related to several pathways were altered differently in different subtypes of mutant plants. In one subtype, the mutant plants had increased expression of genes related to plant defenses and showed enhanced resistance to a necrotrophic plant pathogen. These results suggest multiple functions of UBC22 during plant development and stress response.
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Affiliation(s)
- Sheng Wang
- Department of Biochemistry, Microbiology and Immunology, University of Saskatchewan, Saskatoon, SK, S7N 5E5, Canada
| | - Qiang Li
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, 430070, China
| | - Liang Zhao
- Department of Biochemistry, Microbiology and Immunology, University of Saskatchewan, Saskatoon, SK, S7N 5E5, Canada; Plant Gene Resources of Canada, Saskatoon Research and Development Centre, Agriculture and Agri-Food Canada, Saskatoon, SK, S7N 0X2, Canada
| | - Sanxiong Fu
- Department of Biochemistry, Microbiology and Immunology, University of Saskatchewan, Saskatoon, SK, S7N 5E5, Canada; Institute of Industrial Crops, Jiangsu Academy of Agricultural Sciences, Nanjing, 210014, China
| | - Li Qin
- Department of Biology, University of Saskatchewan, Saskatoon, SK, S7N 5E2, Canada
| | - Yangdou Wei
- Department of Biology, University of Saskatchewan, Saskatoon, SK, S7N 5E2, Canada
| | - Yong-Bi Fu
- Plant Gene Resources of Canada, Saskatoon Research and Development Centre, Agriculture and Agri-Food Canada, Saskatoon, SK, S7N 0X2, Canada
| | - Hong Wang
- Department of Biochemistry, Microbiology and Immunology, University of Saskatchewan, Saskatoon, SK, S7N 5E5, Canada.
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Williams KM, Qie S, Atkison JH, Salazar-Arango S, Alan Diehl J, Olsen SK. Structural insights into E1 recognition and the ubiquitin-conjugating activity of the E2 enzyme Cdc34. Nat Commun 2019; 10:3296. [PMID: 31341161 PMCID: PMC6656757 DOI: 10.1038/s41467-019-11061-8] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Accepted: 06/20/2019] [Indexed: 12/14/2022] Open
Abstract
Ubiquitin (Ub) signaling requires the sequential interactions and activities of three enzymes, E1, E2, and E3. Cdc34 is an E2 that plays a key role in regulating cell cycle progression and requires unique structural elements to function. The molecular basis by which Cdc34 engages its E1 and the structural mechanisms by which its unique C-terminal extension functions in Cdc34 activity are unknown. Here, we present crystal structures of Cdc34 alone and in complex with E1, and a Cdc34~Ub thioester mimetic that represents the product of Uba1-Cdc34 Ub transthiolation. These structures reveal conformational changes in Uba1 and Cdc34 and a unique binding mode that are required for transthiolation. The Cdc34~Ub structure reveals contacts between the Cdc34 C-terminal extension and Ub that stabilize Cdc34~Ub in a closed conformation and are critical for Ub discharge. Altogether, our structural, biochemical, and cell-based studies provide insights into the molecular mechanisms by which Cdc34 function in cells.
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Affiliation(s)
- Katelyn M Williams
- Department of Biochemistry & Molecular Biology and Hollings Cancer Center, Medical University of South Carolina, Charleston, SC, 29425, USA
| | - Shuo Qie
- Department of Biochemistry & Molecular Biology and Hollings Cancer Center, Medical University of South Carolina, Charleston, SC, 29425, USA
| | - James H Atkison
- Department of Biochemistry & Molecular Biology and Hollings Cancer Center, Medical University of South Carolina, Charleston, SC, 29425, USA
| | - Sabrina Salazar-Arango
- Department of Biochemistry & Molecular Biology and Hollings Cancer Center, Medical University of South Carolina, Charleston, SC, 29425, USA
| | - J Alan Diehl
- Department of Biochemistry & Molecular Biology and Hollings Cancer Center, Medical University of South Carolina, Charleston, SC, 29425, USA
| | - Shaun K Olsen
- Department of Biochemistry & Molecular Biology and Hollings Cancer Center, Medical University of South Carolina, Charleston, SC, 29425, USA.
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Abstract
Glioblastoma (GBM) is the most aggressive astrocytoma. Despite maximum treatment, the GBM usually recurs and the patient survival is poor. Thus, understanding the molecular mechanism of GBM progression will be meaningful to ameliorate this situation. In this study, collapsin response mediator protein 2 (CRMP2) and Ubc9 protein levels were evaluated in three GBM cell lines. Sumoylated CRMP2 were enriched and immunoprecipitated using SUMO1 and IgG antibodies. CRMP2-K374A mutant was generated by site-direct mutagenesis. All indicated constructs were transfected into GL15 cells, and the corresponding proliferation-promoting effect was assessed through cell proliferation ratio. The t-CSM peptide was used to disturb Ubc9-CRMP2 interaction. CRMP2 is expressed in all tested GBM cell lines. The Ubc9 protein levels are positively correlated with CRMP2 level, and both can promote GBM cell proliferation. Blocking CRMP2 SUMOylation through SUMOylation-incompetent mutant or small peptide suppresses CRMP2-induced GBM cell proliferation. This study demonstrates that the CRMP2 SUMOylation exists widely in GBM cells and drives glioblastoma proliferation. CRMP2 SUMOylation inhibition can significantly suppress GBM proliferation in vitro.
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Affiliation(s)
- Leilei Wang
- Department of Neurosurgery, Cangzhou Central Hospital, Xinhua West Road, Cangzhou, 061000, Hebei, China
| | - Suzhen Ji
- Department of Emergency, Cangzhou Central Hospital, Xinhua West Road, Cangzhou, 061000, Hebei, China.
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Dudley LJ, Cabodevilla AG, Makar AN, Sztacho M, Michelberger T, Marsh JA, Houston DR, Martens S, Jiang X, Gammoh N. Intrinsic lipid binding activity of ATG16L1 supports efficient membrane anchoring and autophagy. EMBO J 2019; 38:e100554. [PMID: 30936093 PMCID: PMC6484409 DOI: 10.15252/embj.2018100554] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Revised: 02/04/2019] [Accepted: 03/07/2019] [Indexed: 01/06/2023] Open
Abstract
Membrane targeting of autophagy-related complexes is an important step that regulates their activities and prevents their aberrant engagement on non-autophagic membranes. ATG16L1 is a core autophagy protein implicated at distinct phases of autophagosome biogenesis. In this study, we dissected the recruitment of ATG16L1 to the pre-autophagosomal structure (PAS) and showed that it requires sequences within its coiled-coil domain (CCD) dispensable for homodimerisation. Structural and mutational analyses identified conserved residues within the CCD of ATG16L1 that mediate direct binding to phosphoinositides, including phosphatidylinositol 3-phosphate (PI3P). Mutating putative lipid binding residues abrogated the localisation of ATG16L1 to the PAS and inhibited LC3 lipidation. On the other hand, enhancing lipid binding of ATG16L1 by mutating negatively charged residues adjacent to the lipid binding motif also resulted in autophagy inhibition, suggesting that regulated recruitment of ATG16L1 to the PAS is required for its autophagic activity. Overall, our findings indicate that ATG16L1 harbours an intrinsic ability to bind lipids that plays an essential role during LC3 lipidation and autophagosome maturation.
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Affiliation(s)
- Leo J Dudley
- Cancer Research UK Edinburgh Centre, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, UK
| | - Ainara G Cabodevilla
- Cancer Research UK Edinburgh Centre, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, UK
| | - Agata N Makar
- Cancer Research UK Edinburgh Centre, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, UK
| | - Martin Sztacho
- Department of Biochemistry and Cell Biology, Max F. Perutz Laboratories, Vienna Biocenter, University of Vienna, Vienna, Austria
| | - Tim Michelberger
- Cancer Research UK Edinburgh Centre, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, UK
| | - Joseph A Marsh
- Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, UK
| | - Douglas R Houston
- Institute of Quantitative Biology, Biochemistry and Biotechnology, University of Edinburgh, Edinburgh, UK
| | - Sascha Martens
- Department of Biochemistry and Cell Biology, Max F. Perutz Laboratories, Vienna Biocenter, University of Vienna, Vienna, Austria
| | - Xuejun Jiang
- Cell Biology Department, Memorial Sloan Kettering Cancer Centre, New York, NY, USA
| | - Noor Gammoh
- Cancer Research UK Edinburgh Centre, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, UK
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Esmerats JF, Villa-Roel N, Kumar S, Gu L, Salim MT, Ohh M, Taylor WR, Nerem RM, Yoganathan AP, Jo H. Disturbed Flow Increases UBE2C (Ubiquitin E2 Ligase C) via Loss of miR-483-3p, Inducing Aortic Valve Calcification by the pVHL (von Hippel-Lindau Protein) and HIF-1α (Hypoxia-Inducible Factor-1α) Pathway in Endothelial Cells. Arterioscler Thromb Vasc Biol 2019; 39:467-481. [PMID: 30602302 PMCID: PMC6393167 DOI: 10.1161/atvbaha.118.312233] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Objective- Calcific aortic valve (AV) disease, characterized by AV sclerosis and calcification, is a major cause of death in the aging population; however, there are no effective medical therapies other than valve replacement. AV calcification preferentially occurs on the fibrosa side, exposed to disturbed flow (d-flow), whereas the ventricularis side exposed to predominantly stable flow remains protected by unclear mechanisms. Here, we tested the role of novel flow-sensitive UBE2C (ubiquitin E2 ligase C) and microRNA-483-3p (miR-483) in flow-dependent AV endothelial function and AV calcification. Approach and Results- Human AV endothelial cells and fresh porcine AV leaflets were exposed to stable flow or d-flow. We found that UBE2C was upregulated by d-flow in human AV endothelial cells in the miR-483-dependent manner. UBE2C mediated OS-induced endothelial inflammation and endothelial-mesenchymal transition by increasing the HIF-1α (hypoxia-inducible factor-1α) level. UBE2C increased HIF-1α by ubiquitinating and degrading its upstream regulator pVHL (von Hippel-Lindau protein). These in vitro findings were corroborated by immunostaining studies using diseased human AV leaflets. In addition, we found that reduction of miR-483 by d-flow led to increased UBE2C expression in human AV endothelial cells. The miR-483 mimic protected against endothelial inflammation and endothelial-mesenchymal transition in human AV endothelial cells and calcification of porcine AV leaflets by downregulating UBE2C. Moreover, treatment with the HIF-1α inhibitor (PX478) significantly reduced porcine AV calcification in static and d-flow conditions. Conclusions- These results suggest that miR-483 and UBE2C and pVHL are novel flow-sensitive anti- and pro-calcific AV disease molecules, respectively, that regulate the HIF-1α pathway in AV. The miR-483 mimic and HIF-1α pathway inhibitors may serve as potential therapeutics of calcific AV disease.
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Affiliation(s)
- Joan Fernandez Esmerats
- Wallace H. Coulter Department of Biomedical Engineering at Georgia Institute of Technology and Emory University
| | - Nicolas Villa-Roel
- Wallace H. Coulter Department of Biomedical Engineering at Georgia Institute of Technology and Emory University
| | - Sandeep Kumar
- Wallace H. Coulter Department of Biomedical Engineering at Georgia Institute of Technology and Emory University
| | - Lina Gu
- Wallace H. Coulter Department of Biomedical Engineering at Georgia Institute of Technology and Emory University
| | - Md Tausif Salim
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology
| | - Michael Ohh
- Department of Biochemistry, Faculty of Medicine, University of Toronto, Toronto, CA
| | - W. Robert Taylor
- Wallace H. Coulter Department of Biomedical Engineering at Georgia Institute of Technology and Emory University
- Division of Cardiology, Department of Medicine, Emory University
| | - Robert M. Nerem
- Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology. Atlanta, GA, USA
| | - Ajit P. Yoganathan
- Wallace H. Coulter Department of Biomedical Engineering at Georgia Institute of Technology and Emory University
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology
| | - Hanjoong Jo
- Wallace H. Coulter Department of Biomedical Engineering at Georgia Institute of Technology and Emory University
- Division of Cardiology, Department of Medicine, Emory University
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Hsu SH, Chen SH, Kuo CC, Chang JY. Ubiquitin-conjugating enzyme E2 B regulates the ubiquitination of O 6-methylguanine-DNA methyltransferase and BCNU sensitivity in human nasopharyngeal carcinoma cells. Biochem Pharmacol 2018; 158:327-338. [PMID: 30449727 DOI: 10.1016/j.bcp.2018.10.029] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Accepted: 10/25/2018] [Indexed: 02/06/2023]
Abstract
O6-Methylguanine-DNA methyltransferase (MGMT) is a DNA repair enzyme that removes the alkyl groups from the O6 position of guanine and is then degraded via ubiquitin-mediated degradation. Previous studies indicated that 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) facilitates the ubiquitination and degradation of MGMT in several types of cancer cells. However, the underlying mechanism of MGMT ubiquitination remains unclear. In this study, we demonstrated for the first time that ubiquitin-conjugating enzyme E2 B (UBE2B) is a novel regulator of MGMT ubiquitination mediated by BCNU in nasopharyngeal carcinoma (NPC) cells. The E3 ubiquitin ligase RAD18, a partner of UBE2B, is also involved in BCNU-mediated MGMT ubiquitination. Overexpression/knockdown of UBE2B enhanced/reduced BCNU-mediated MGMT ubiquitination. Surprisingly, UBE2B knockdown significantly increased BCNU cytotoxicity in NPC cells. Therefore, loss of UBE2B seems to disrupt ubiquitin-mediated degradation of alkylated MGMT. We found that UBE2B knockdown reduced MGMT activity, suggesting that loss of UBE2B leads to the accumulation of deactivated MGMT and suppresses MGMT protein turnover in BCNU-treated cells. These findings indicate that UBE2B modulates sensitivity to BCNU in NPC cells by regulating MGMT ubiquitination.
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Affiliation(s)
- Shih-Han Hsu
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan; National Institute of Cancer Research, National Health Research Institutes, Tainan, Taiwan
| | - Shang-Hung Chen
- National Institute of Cancer Research, National Health Research Institutes, Tainan, Taiwan; Division of Hematology/Oncology, Department of Internal Medicine, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Ching-Chuan Kuo
- Institute of Biotechnology and Pharmaceutical Research, National Health Research Institutes, Zhunan, Taiwan
| | - Jang-Yang Chang
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan; National Institute of Cancer Research, National Health Research Institutes, Tainan, Taiwan; Division of Hematology/Oncology, Department of Internal Medicine, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
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10
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Chen G, Wu C, He L, Qiu Z, Zhang S, Zhang Y, Guo L, Zeng D, Hu J, Ren D, Qian Q, Zhu L. Knocking Out the Gene RLS1 Induces Hypersensitivity to Oxidative Stress and Premature Leaf Senescence in Rice. Int J Mol Sci 2018; 19:ijms19102853. [PMID: 30241349 PMCID: PMC6213272 DOI: 10.3390/ijms19102853] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Revised: 09/16/2018] [Accepted: 09/17/2018] [Indexed: 02/07/2023] Open
Abstract
Improving a plant’s level of tolerance to oxidative stress can frequently also enhance its tolerance to several other abiotic stresses. Here, a screen of a japonica type rice T-DNA insertion mutant library identified a highly oxidative stress-sensitive mutant. The line exhibited premature leaf senescence, starting at the three-leaf stage, and the symptoms were particularly severe from the five-leaf stage onwards. The leaves progressively lost chlorophyll, suffered protein degradation and were compromised with respect to their photosynthetic activity; their leaf mesophyll and bulliform cells became shrunken, and several senescence-associated genes (SAGs), senescence-associated transcription factor genes (SATFs) and autophagy-related genes (ATGs) were progressively up-regulated. The product of the gene inactivated by the mutation, identified via positional cloning, was putatively a ubiquitin-conjugating enzyme. The gene was denoted here as RLS1 (reactive oxygen species-sensitive leaf senescence1). The phenotype of plants in which RLS1 was knocked down using RNA interference was comparable to that of the rls1 mutant. A comparative analysis of the knock-out line and the wild type leaves showed that the former accumulated more hydrogen peroxide and more malondialdehyde, expressed a heightened level of superoxide dismutase activity and a decreased level of catalase activity, and exhibited an altered transcriptional profile with respect to several SAGs, SATFs and ATGs, and that these effects were magnified when the plants were exposed to oxidative stress. The product of RLS1 is presumed to be a critical component of the rice oxidative stress response and is involved in ROS (reactive oxygen species)-mediated leaf senescence.
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Affiliation(s)
- Guang Chen
- State Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou 310006, China.
| | - Chao Wu
- Institute of Horticulture, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China.
| | - Lei He
- State Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou 310006, China.
| | - Zhennan Qiu
- State Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou 310006, China.
| | - Sen Zhang
- State Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou 310006, China.
| | - Yu Zhang
- State Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou 310006, China.
| | - Longbiao Guo
- State Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou 310006, China.
| | - Dali Zeng
- State Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou 310006, China.
| | - Jiang Hu
- State Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou 310006, China.
| | - Deyong Ren
- State Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou 310006, China.
| | - Qian Qian
- State Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou 310006, China.
| | - Li Zhu
- State Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou 310006, China.
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Somasagara RR, Spencer SM, Tripathi K, Clark DW, Mani C, da Silva LM, Scalici J, Kothayer H, Westwell AD, Rocconi RP, Palle K. RAD6 promotes DNA repair and stem cell signaling in ovarian cancer and is a promising therapeutic target to prevent and treat acquired chemoresistance. Oncogene 2017; 36:6680-6690. [PMID: 28806395 PMCID: PMC5709226 DOI: 10.1038/onc.2017.279] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Revised: 06/14/2017] [Accepted: 07/07/2017] [Indexed: 12/28/2022]
Abstract
Ovarian cancer (OC) is the most deadly gynecological cancer and unlike most other neoplasms, survival rates for OC have not significantly improved in recent decades. We show that RAD6, an ubiquitin-conjugating enzyme, is significantly overexpressed in ovarian tumors and its expression increases in response to carboplatin chemotherapy. RAD6 expression correlated strongly with acquired chemoresistance and malignant behavior of OC cells, expression of stem cell genes and poor prognosis of OC patients, suggesting an important role for RAD6 in ovarian tumor progression. Upregulated RAD6 enhances DNA damage tolerance and repair efficiency of OC cells and promotes their survival. Increased RAD6 levels cause histone 2B ubiquitination-mediated epigenetic changes that stimulate transcription of stem cell genes, including ALDH1A1 and SOX2, leading to a cancer stem cell phenotype, which is implicated in disease recurrence and metastasis. Downregulation of RAD6 or its inhibition using a small molecule inhibitor attenuated DNA repair signaling and expression of cancer stem cells markers and sensitized chemoresistant OC cells to carboplatin. Together, these results suggest that RAD6 could be a therapeutic target to prevent and treat acquired chemoresistance and disease recurrence in OC and enhance the efficacy of standard chemotherapy.
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Affiliation(s)
- Ranganatha R. Somasagara
- Department of Oncologic Sciences, Mitchell Cancer Institute, University of South Alabama, 1660 Springhill Avenue, Mobile, Alabama 36604, USA
| | - Sebastian M. Spencer
- Department of Oncologic Sciences, Mitchell Cancer Institute, University of South Alabama, 1660 Springhill Avenue, Mobile, Alabama 36604, USA
| | - Kaushlendra Tripathi
- Department of Oncologic Sciences, Mitchell Cancer Institute, University of South Alabama, 1660 Springhill Avenue, Mobile, Alabama 36604, USA
| | - David W. Clark
- Department of Oncologic Sciences, Mitchell Cancer Institute, University of South Alabama, 1660 Springhill Avenue, Mobile, Alabama 36604, USA
| | - Chinnadurai Mani
- Department of Oncologic Sciences, Mitchell Cancer Institute, University of South Alabama, 1660 Springhill Avenue, Mobile, Alabama 36604, USA
| | - Luciana Madeira da Silva
- Department of Oncologic Sciences, Mitchell Cancer Institute, University of South Alabama, 1660 Springhill Avenue, Mobile, Alabama 36604, USA
| | - Jennifer Scalici
- Department of Oncologic Sciences, Mitchell Cancer Institute, University of South Alabama, 1660 Springhill Avenue, Mobile, Alabama 36604, USA
| | - Hend Kothayer
- Department of Medicinal Chemistry, Faculty of Pharmacy, Zagazig University, Egypt
| | - Andrew D. Westwell
- School of Pharmacy and Pharmaceutical Sciences, Cardiff University, Redwood Building, King Edward VII Avenue, Cardiff CF10 3NB, Wales, UK
| | - Rodney P. Rocconi
- Department of Oncologic Sciences, Mitchell Cancer Institute, University of South Alabama, 1660 Springhill Avenue, Mobile, Alabama 36604, USA
| | - Komaraiah Palle
- Department of Oncologic Sciences, Mitchell Cancer Institute, University of South Alabama, 1660 Springhill Avenue, Mobile, Alabama 36604, USA
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12
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Vila IK, Yao Y, Kim G, Xia W, Kim H, Kim SJ, Park MK, Hwang JP, González-Billalabeitia E, Hung MC, Song SJ, Song MS. A UBE2O-AMPKα2 Axis that Promotes Tumor Initiation and Progression Offers Opportunities for Therapy. Cancer Cell 2017; 31:208-224. [PMID: 28162974 PMCID: PMC5463996 DOI: 10.1016/j.ccell.2017.01.003] [Citation(s) in RCA: 94] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Revised: 10/10/2016] [Accepted: 01/05/2017] [Indexed: 01/06/2023]
Abstract
UBE2O is localized in the 17q25 locus, which is known to be amplified in human cancers, but its role in tumorigenesis remains undefined. Here we show that Ube2o deletion in MMTV-PyVT or TRAMP mice profoundly impairs tumor initiation, growth, and metastasis, while switching off the metabolic reprogramming of tumor cells. Mechanistically, UBE2O specifically targets AMPKα2 for ubiquitination and degradation, and thereby promotes activation of the mTOR-HIF1α pathway. Notably, inactivation of AMPKα2, but not AMPKα1, abrogates the tumor attenuation caused by UBE2O loss, while treatment with rapamycin or inhibition of HIF1α ablates UBE2O-dependent tumor biology. Finally, pharmacological blockade of UBE2O inhibits tumorigenesis through the restoration of AMPKα2, suggesting the UBE2O-AMPKα2 axis as a potential cancer therapeutic target.
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Affiliation(s)
- Isabelle K Vila
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Yixin Yao
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Goeun Kim
- Soonchunhyang Institute of Medi-bio Science, Soonchunhyang University, Cheonan-si, Chungcheongnam-do 31151, Republic of Korea
| | - Weiya Xia
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Hyejin Kim
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Sun-Joong Kim
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Mi-Kyung Park
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - James P Hwang
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | | | - Mien-Chie Hung
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA; Cancer Biology Program, The University of Texas Graduate School of Biomedical Sciences, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA; Center for Molecular Medicine and Graduate Institute of Cancer Biology, China Medical University, Taichung 404, Taiwan
| | - Su Jung Song
- Soonchunhyang Institute of Medi-bio Science, Soonchunhyang University, Cheonan-si, Chungcheongnam-do 31151, Republic of Korea.
| | - Min Sup Song
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA; Cancer Biology Program, The University of Texas Graduate School of Biomedical Sciences, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.
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13
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Zhang GW, Cai HC, Shang XJ. [Ubiquitin-proteasome system and sperm DNA repair: An update]. Zhonghua Nan Ke Xue 2016; 22:834-837. [PMID: 29071883] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The ubiquitin-proteasome system (UPS) is a proteasome system widely present in the human body, which is composed of ubiquitin (Ub), ubiquitin activating enzymes (E1), ubiquitin conjugating enzymes (E2), ubiquitin protein ligases (E3), 26S proteasome, and deubiquitinating enzymes (DUBs) and involved in cell cycle regulation, immune response, signal transduction, DNA repair as well as protein degradation. Sperm DNA is vulnerable to interference or damage in the progression of chromosome association and homologous recombination. Recent studies show that UPS participates in DNA repair in spermatogenesis by modulating DNA repair enzymes via ubiquitination, assisting in the identification of DNA damage sites, raising damage repair-related proteins, initiating the DNA repair pathway, maintaining chromosome stability, and ensuring the normal process of spermatogenesis.
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Affiliation(s)
- Guo-Wei Zhang
- Department of Andrology, Jinling Hospital Affiliated to Southern Medical University / Nanjing General Hospital of Nanjing Military Region, Nanjing, Jiangsu 210002, China
| | - Hong-Cai Cai
- Department of Andrology, Jinling Hospital Affiliated to Southern Medical University / Nanjing General Hospital of Nanjing Military Region, Nanjing, Jiangsu 210002, China
| | - Xue-Jun Shang
- Department of Andrology, Jinling Hospital Affiliated to Southern Medical University / Nanjing General Hospital of Nanjing Military Region, Nanjing, Jiangsu 210002, China
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14
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Bao LJ, Jaramillo MC, Zhang ZB, Zheng YX, Yao M, Zhang DD, Yi XF. Nrf2 induces cisplatin resistance through activation of autophagy in ovarian carcinoma. Int J Clin Exp Pathol 2014; 7:1502-1513. [PMID: 24817946 PMCID: PMC4014230] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Received: 01/26/2014] [Accepted: 03/01/2014] [Indexed: 06/03/2023]
Abstract
UNLABELLED Cisplatin resistance is a major problem affecting ovarian carcinoma treatment. NF-E2-related factor 2 (Nrf2), a nuclear transcription factor, plays an important role in chemotherapy resistance. However, the underlying mechanism by which Nrf2 mediates cisplatin chemoresistance is unclear. METHODS The human ovarian carcinoma cell line, A2780, and its cisplatin-resistant variant, A2780cp were cultivated. Cell viability was determined with WST-8 assay. Western blot was applied to detect the expression of Nrf2, Nrf2 target genes, and autophagy-related proteins. RNA interference was used to knock down target genes. Annexin V and propidium iodide (PI) staining was utilized to quantify apoptosis. The ultrastructural analysis of autophagosomes was performed by transmission electron microscopy (TEM). RESULTS Nrf2 and its targeting genes, NQO1 and HO-1, are overexpressed in A2780cp cells compared with A2780 cells. Knocking down Nrf2 sensitized A2780cp cells to cisplatin treatment and decreased autophagy-related genes, Atg3, Atg6, Atg12 and p62 in both mRNA and protein levels. Furthermore, we demonstrated that in both cell lines cisplatin could induce the formation of autophagosomes and upregulate the expression of autophagy-related genes Atg3, Atg6 and Atg12. Treatment with an autophagy inhibitor, 3-Methyladenine (3-MA), or beclin 1 siRNA enhanced cisplatin-induced cell death in A2780cp cells, suggesting that inhibition of autophagy renders resistant cells to be more sensitive to cisplatin. Taken together, Nrf2 signaling may regulate cisplatin resistance by activating autophagy. CONCLUSIONS Nrf2-activated autophagy may function as a novel mechanism causing cisplatin-resistance.
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Affiliation(s)
- Ling-Jie Bao
- Obstetrics and Gynecology Hospital, Fudan University Shanghai 200011, China ; Department of Obstetrics and Gynecology of Shanghai Medical School, Fudan University Shanghai 200011, China ; Shanghai Key Laboratory of Female Reproductive Endocrine Related Diseases Shanghai 200011, China
| | - Melba C Jaramillo
- Department of Pharmacology and Toxicology, University of Arizona Arizona, USA
| | - Zhen-Bo Zhang
- Department of Obstetrics and Gynecology, Shanghai First Peoples' Hospital, Jiaotong University Shanghai 200080, China
| | - Yun-Xi Zheng
- Obstetrics and Gynecology Hospital, Fudan University Shanghai 200011, China ; Department of Obstetrics and Gynecology of Shanghai Medical School, Fudan University Shanghai 200011, China ; Shanghai Key Laboratory of Female Reproductive Endocrine Related Diseases Shanghai 200011, China
| | - Ming Yao
- State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of Medicine Shanghai 200032, China
| | - Donna D Zhang
- Department of Pharmacology and Toxicology, University of Arizona Arizona, USA
| | - Xiao-Fang Yi
- Obstetrics and Gynecology Hospital, Fudan University Shanghai 200011, China ; Department of Obstetrics and Gynecology of Shanghai Medical School, Fudan University Shanghai 200011, China ; Shanghai Key Laboratory of Female Reproductive Endocrine Related Diseases Shanghai 200011, China
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15
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Park BS, Seo JS, Chua NH. NITROGEN LIMITATION ADAPTATION recruits PHOSPHATE2 to target the phosphate transporter PT2 for degradation during the regulation of Arabidopsis phosphate homeostasis. Plant Cell 2014; 26:454-64. [PMID: 24474629 PMCID: PMC3963589 DOI: 10.1105/tpc.113.120311] [Citation(s) in RCA: 165] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2013] [Revised: 12/26/2013] [Accepted: 01/06/2013] [Indexed: 05/18/2023]
Abstract
The NITROGEN LIMITATION ADAPTION (NLA) gene was initially shown to function in nitrogen limitation responses; however, recent work shows that the nla mutant hyperaccumulates Pi, phenocopying the Pi signaling mutant pho2. PHO2 encodes a putative E2 conjugase, UBC24. Here, we show that NLA is an E3 ligase that specifically requires UBC24 for polyubiquitination in Arabidopsis thaliana. Among five members of the Pht1 Pi-transporter family tested, NLA associates only with PT2 (Pht1;4). The NLA-UBC24 pair mediates polyubiquitination of PT2 but not PT1. Posttranslational decay of PT2 at high Pi is blocked in pho2 and inhibited by MG132, indicating the requirement of UBC24 and 26S proteasomes. Consistent with NLA/UBC24 function, induced NLA expression causes a UBC24-dependent decrease in PT2 levels. Confocal microscopy of fusion proteins revealed an NLA/PT2 interaction at the plasma membrane. Collectively, these results show that under Pi-replete conditions, NLA and UBC24 target the PT2 transporter for destruction. During the Pi deprivation response, NLA and PHO2 transcripts are cleaved by miR399 and miR827, respectively, and our results suggest that this downregulation relieves the posttranslational repression of PT2, allowing it to accumulate and participate in Pi uptake. Our work provides additional molecular details describing Pi signaling/homeostasis regulation by identifying NLA and UBC24 as partners and PT2 as one of their downstream targets.
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16
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Ma X, Yang L, Yang Y, Li M, Li W, Xue L. dUev1a modulates TNF-JNK mediated tumor progression and cell death in Drosophila. Dev Biol 2013; 380:211-21. [PMID: 23726905 DOI: 10.1016/j.ydbio.2013.05.013] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2012] [Revised: 04/22/2013] [Accepted: 05/13/2013] [Indexed: 01/01/2023]
Abstract
Loss of cell polarity cooperates with oncogenic Ras to induce JNK-dependent tumor growth and invasion. To identify additional genes that modulate tumor progression, we have performed a genetic screen in Drosophila and found that loss of dUev1a, the ortholog of mammalian Uev1, suppressed lgl(-/-)/Ras(V12) induced JNK-mediated tumor growth and invasion. Furthermore, loss of dUev1a suppressed TNF ortholog Eiger-induced JNK-mediated cell invasion and cell death. Finally, dUev1a cooperated with Bendless to activate JNK signaling through dTRAF2. Together, our data indicate that dUev1a encodes an essential component of the evolutionary conserved TNF-JNK signaling pathway that modulates tumor progression and cell death in metazoan.
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Affiliation(s)
- Xianjue Ma
- Department of Interventional Radiology, Shanghai 10th People's Hospital, Shanghai Key Laboratory of Signaling and Disease Research, School of Life Science and Technology, Tongji University, Shanghai 200092, China
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17
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Abstract
Breast cancer is the most common malignancy in women and a significant cause of morbidity and mortality. Sub-types of breast cancer defined by the expression of steroid hormones and Her2/Neu oncogene have distinct prognosis and undergo different therapies. Besides differing in their phenotype, sub-types of breast cancer display various molecular lesions that participate in their pathogenesis. BRCA1 is one of the common hereditary cancer predisposition genes and encodes for an ubiquitin ligase. Ubiquitin ligases or E3 enzymes participate together with ubiquitin activating enzyme and ubiquitin conjugating enzymes in the attachment of ubiquitin (ubiquitination) in target proteins. Ubiquitination is a post-translational modification regulating multiple cell functions. It also plays important roles in carcinogenesis in general and in breast carcinogenesis in particular. Ubiquitin conjugating enzymes are a central component of the ubiquitination machinery and are often perturbed in breast cancer. This paper will discuss ubiquitin and ubiquitin-like proteins conjugating enzymes participating in breast cancer pathogenesis, their relationships with other proteins of the ubiquitination machinery and their role in phenotype of breast cancer sub-types.
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Affiliation(s)
- Ioannis A Voutsadakis
- Centre Pluridisciplinaire d'Oncologie, BH06, University Hospital of Lausanne, Lausanne, Switzerland.
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18
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Miura K, Sato A, Ohta M, Furukawa J. Increased tolerance to salt stress in the phosphate-accumulating Arabidopsis mutants siz1 and pho2. Planta 2011; 234:1191-9. [PMID: 21748325 DOI: 10.1007/s00425-011-1476-y] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2011] [Accepted: 06/28/2011] [Indexed: 05/23/2023]
Abstract
High salinity is an environmental factor that inhibits plant growth and development, leading to large losses in crop yields. We report here that mutations in SIZ1 or PHO2, which cause more accumulation of phosphate compared with the wild type, enhance tolerance to salt stress. The siz1 and pho2 mutations reduce the uptake and accumulation of Na(+). These mutations are also able to suppress the Na(+) hypersensitivity of the sos3-1 mutant, and genetic analyses suggest that SIZ1 and SOS3 or PHO2 and SOS3 have an additive effect on the response to salt stress. Furthermore, the siz1 mutation cannot suppress the Li(+) hypersensitivity of the sos3-1 mutant. These results indicate that the phosphate-accumulating mutants siz1 and pho2 reduce the uptake and accumulation of Na(+), leading to enhanced salt tolerance, and that, genetically, SIZ1 and PHO2 are likely independent of SOS3-dependent salt signaling.
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Affiliation(s)
- Kenji Miura
- Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, 305-8572, Japan.
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19
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Abstract
Sumoylation, the covalent attachment of SUMO (Small Ubiquitin-Like Modifier) to proteins, differs from other Ubl (Ubiquitin-like) pathways. In sumoylation, E2 ligase Ubc9 can function without E3 enzymes, albeit with lower reaction efficiency. Here, we study the mechanism through which E3 ligase RanBP2 triggers target recognition and catalysis by E2 Ubc9. Two mechanisms were proposed for sumoylation. While in both the first step involves Ubc9 conjugation to SUMO, the subsequent sequence of events differs: in the first E2-SUMO forms a complex with the target and E3, followed by SUMO transfer to the target. In the second, Ubc9-SUMO binds to the target and facilitates SUMO transfer without E3. Using dynamic correlations obtained from explicit solvent molecular dynamic simulations we illustrate the key roles played by allostery in both mechanisms. Pre-existence of conformational states explains the experimental observations that sumoylation can occur without E3, even though at a reduced rate. Furthermore, we propose a mechanism for enhancement of sumoylation by E3. Analysis of the conformational ensembles of the complex of E2 conjugated to SUMO illustrates that the E2 enzyme is already largely pre-organized for target binding and catalysis; E3 binding shifts the equilibrium and enhances these pre-existing populations. We further observe that E3 binding regulates allosterically the key residues in E2, Ubc9 Asp100/Lys101 E2, for the target recognition.
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Affiliation(s)
- Melda Tozluoğlu
- Polymer Research Center & Chemical Engineering Department, Bogazici University, Istanbul, Turkey
| | - Ezgi Karaca
- Polymer Research Center & Chemical Engineering Department, Bogazici University, Istanbul, Turkey
| | - Ruth Nussinov
- Basic Science Program, SAIC-Frederick, Inc., Center for Cancer Research Nanobiology Program, NCI-Frederick, Frederick, Maryland, United States of America
- Sackler Institute of Molecular Medicine, Department of Human Genetics and Molecular Medicine, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
- * E-mail: (TH); (RN)
| | - Türkan Haliloğlu
- Polymer Research Center & Chemical Engineering Department, Bogazici University, Istanbul, Turkey
- * E-mail: (TH); (RN)
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20
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Abstract
The tumour necrosis factor receptor 1 (TNFR1) activates prosurvival pathways by induction of the NFkappaB pathway and induces cell death via apoptosis. The ubiquitin-conjugating enzyme, Ubc13, mediates the ubiquitylation-dependent formation of protein complexes crucial for the activation and regulation of both pathways. We describe a new role for Ubc13 in the regulation of TNFR1 activity after UV stimulation. Depletion of Ubc13 by RNAi produced a decreased NFkappaB activity and increased apoptosis after stimulation by TNFalpha and UV-C light. These results are consistent with the function of Ubc13 in the ubiquitylation of RIP1, which controls the proapoptotic or prosurvival response after TNFR1 activation. Moreover, we demonstrated that UV-C light induces a close interaction between the Ubc13 protein and the TNFR1 receptor. In the absence of Ubc13 TNFR1 clustering was increased. We conclude that Ubc13 has a regulatory role for the activation of TNFR1 and hence, apoptotic cell death. Thus, our results elucidated a new role for Ubc13 in the regulation of prosurvival or proapoptotic processes, which is upstream of so far investigated functions.
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Affiliation(s)
- Marita Angermeier
- Institute of Radiation Biology, Helmholtz Centre Munich, German Research Centre for Environmental Health, Ingolstaedter Landstrasse 1, Neuherberg, Germany
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21
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Zhu S, Sachdeva M, Wu F, Lu Z, Mo YY. Ubc9 promotes breast cell invasion and metastasis in a sumoylation-independent manner. Oncogene 2010; 29:1763-72. [PMID: 20023705 PMCID: PMC2845735 DOI: 10.1038/onc.2009.459] [Citation(s) in RCA: 93] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2009] [Revised: 11/06/2009] [Accepted: 11/12/2009] [Indexed: 12/18/2022]
Abstract
Ubc9 is an E2-conjugating enzyme that transfers the activated small ubiquitin-like modifier (SUMO) to protein substrates, and thus it has an important function in sumoylation-mediated cellular pathways. We have earlier reported that Ubc9 promotes tumor growth in the xenograft mouse model using breast cancer cell line MCF-7 in part through regulation of Bcl-2 expression. In this study, we show that ectopic expression of wild-type Ubc9 (Ubc9-WT) promotes cell invasion and metastasis. Surprisingly, the dominant negative mutant Ubc9 (Ubc9-DN) also causes the same phenotype, indicating that the ability of Ubc9 to promote invasion and metastasis is distinct from its ability to conjugate SUMO to protein substrates. Of considerable interest, several microRNAs such as miR-224 are regulated by Ubc9. Although ectopic expression of Ubc9 causes downregulation of miR-224, suppression of Ubc9 by Ubc9-siRNAs leads to its upregulation. We further show that miR-224 can inhibit cell invasion and directly targets CDC42 and CXCR4, and that suppression of CDC42 and CXCR4 by RNAi causes inhibition of Ubc9-mediated invasion. Together, these results show a molecular link between Ubc9 and the metastasis genes such as CDC42 and CXCR4, and thus provide new insight into the mechanism by which Ubc9 promotes tumor invasion and metastasis.
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Affiliation(s)
- Shuomin Zhu
- Department of Medical Microbiology, Immunology and Cell Biology, Southern Illinois University School of Medicine, Springfield, IL
| | - Mohit Sachdeva
- Department of Medical Microbiology, Immunology and Cell Biology, Southern Illinois University School of Medicine, Springfield, IL
| | - Fangting Wu
- Department of Medical Microbiology, Immunology and Cell Biology, Southern Illinois University School of Medicine, Springfield, IL
| | - Zhaohui Lu
- Department of Medical Microbiology, Immunology and Cell Biology, Southern Illinois University School of Medicine, Springfield, IL
| | - Yin-Yuan Mo
- Department of Medical Microbiology, Immunology and Cell Biology, Southern Illinois University School of Medicine, Springfield, IL
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22
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Abstract
Retinoic acid-inducible gene-I (RIG-I) functions as an intracellular pattern recognition receptor (PRR) that recognizes the 5'-triphosphate moiety of single-stranded RNA viruses to initiate the innate immune response. Previous studies have shown that Lys63-linked ubiquitylation is required for RIG-I activation and the downstream anti-viral type I interferon (IFN-I) induction. Herein we reported that, RIG-I was also modified by small ubiquitin-like modifier-1 (SUMO-1). Functional analysis showed that RIG-I SUMOylation enhanced IFN-I production through increased ubiquitylation and the interaction with its downstream adaptor molecule Cardif. Our results therefore suggested that SUMOylation might serve as an additional regulatory tier for RIG-I activation and IFN-I signaling.
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Affiliation(s)
- Zhiqiang Mi
- Center for Molecular Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101 China
- Key Laboratory of Infection and Immunity of Chinese Academy of Sciences, Institute of Biophysics, Beijing, 100101 China
| | - Jihuan Fu
- Key Laboratory of Infection and Immunity of Chinese Academy of Sciences, Institute of Biophysics, Beijing, 100101 China
| | - Yanbao Xiong
- Key Laboratory of Infection and Immunity of Chinese Academy of Sciences, Institute of Biophysics, Beijing, 100101 China
| | - Hong Tang
- Key Laboratory of Infection and Immunity of Chinese Academy of Sciences, Institute of Biophysics, Beijing, 100101 China
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23
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Motegi A. [Maintenance of genome stability though Ubc13-dependent ubiquitination]. Seikagaku 2009; 81:601-605. [PMID: 19697864] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Affiliation(s)
- Akira Motegi
- Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Yoshida Konoe, Sakyo-ku, Kyoto 606-8501, Japan
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24
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Chen X, Ding B, LeJeune D, Ruggiero C, Li S. Rpb1 sumoylation in response to UV radiation or transcriptional impairment in yeast. PLoS One 2009; 4:e5267. [PMID: 19384408 PMCID: PMC2668072 DOI: 10.1371/journal.pone.0005267] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2008] [Accepted: 03/24/2009] [Indexed: 11/18/2022] Open
Abstract
Covalent modifications of proteins by ubiquitin and the Small Ubiquitin-like MOdifier (SUMO) have been revealed to be involved in a plethora of cellular processes, including transcription, DNA repair and DNA damage responses. It has been well known that in response to DNA damage that blocks transcription elongation, Rpb1, the largest subunit of RNA polymerase II (Pol II), is ubiquitylated and subsequently degraded in mammalian and yeast cells. However, it is still an enigma regarding how Pol II responds to damaged DNA and conveys signal(s) for DNA damage-related cellular processes. We found that Rpb1 is also sumoylated in yeast cells upon UV radiation or impairment of transcription elongation, and this modification is independent of DNA damage checkpoint activation. Ubc9, an E2 SUMO conjugase, and Siz1, an E3 SUMO ligase, play important roles in Rpb1 sumoylation. K1487, which is located in the acidic linker region between the C-terminal domain and the globular domain of Rpb1, is the major sumoylation site. Rpb1 sumoylation is not affected by its ubiquitylation, and vice versa, indicating that the two processes do not crosstalk. Abolishment of Rpb1 sumoylation at K1487 does not affect transcription elongation or transcription coupled repair (TCR) of UV-induced DNA damage. However, deficiency in TCR enhances UV-induced Rpb1 sumoylation, presumably due to the persistence of transcription-blocking DNA lesions in the transcribed strand of a gene. Remarkably, abolishment of Rpb1 sumoylation at K1487 causes enhanced and prolonged UV-induced phosphorylation of Rad53, especially in TCR-deficient cells, suggesting that the sumoylation plays a role in restraining the DNA damage checkpoint response caused by transcription-blocking lesions. Our results demonstrate a novel covalent modification of Rpb1 in response to UV induced DNA damage or transcriptional impairment, and unravel an important link between the modification and the DNA damage checkpoint response.
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Affiliation(s)
- Xuefeng Chen
- Department of Comparative Biomedical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, Louisiana, United States of America
| | - Baojin Ding
- Department of Comparative Biomedical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, Louisiana, United States of America
| | - Danielle LeJeune
- Department of Comparative Biomedical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, Louisiana, United States of America
| | - Christine Ruggiero
- Department of Comparative Biomedical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, Louisiana, United States of America
| | - Shisheng Li
- Department of Comparative Biomedical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, Louisiana, United States of America
- * E-mail:
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25
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Motegi A, Takeda S. [Function of homologous recombination-mediated DNA repair]. Tanpakushitsu Kakusan Koso 2009; 54:450-458. [PMID: 21089491] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
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26
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Hishida T. [DNA damage tolerance through replication bypass of stalled replication forks]. Tanpakushitsu Kakusan Koso 2009; 54:388-393. [PMID: 21089480] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
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27
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Okumura F. [Regulation of immune response by ubiquitin-like molecule ISG15]. Seikagaku 2009; 81:223-232. [PMID: 19378789] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Affiliation(s)
- Fumihiko Okumura
- Department of Biochemistry, Graduate School of Medicine, Hokkaido University, N15, W7, Kita-ku, Sapporo 060-8638, Japan
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28
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Cao Y, Dai Y, Cui S, Ma L. Histone H2B monoubiquitination in the chromatin of FLOWERING LOCUS C regulates flowering time in Arabidopsis. Plant Cell 2008; 20:2586-602. [PMID: 18849490 PMCID: PMC2590739 DOI: 10.1105/tpc.108.062760] [Citation(s) in RCA: 183] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2008] [Revised: 09/15/2008] [Accepted: 09/21/2008] [Indexed: 05/17/2023]
Abstract
Ubiquitination is one of many known histone modifications that regulate gene expression. Here, we examine the Arabidopsis thaliana homologs of the yeast E2 and E3 enzymes responsible for H2B monoubiquitination (H2Bub1). Arabidopsis has two E3 homologs (HISTONE MONOUBIQUITINATION1 [HUB1] and HUB2) and three E2 homologs (UBIQUITIN CARRIER PROTEIN [UBC1] to UBC3). hub1 and hub2 mutants show the loss of H2Bub1 and early flowering. By contrast, single ubc1, ubc2, or ubc3 mutants show no flowering defect; only ubc1 ubc2 double mutants, and not double mutants with ubc3, show early flowering and H2Bub1 defects. This suggests that ubc1 and ubc2 are redundant, but ubc3 is not involved in flowering time regulation. Protein interaction analysis showed that HUB1 and HUB2 interact with each other and with UBC1 and UBC2, as well as self-associating. The expression of FLOWERING LOCUS C (FLC) and its homologs was repressed in hub1, hub2, and ubc1 ubc2 mutant plants. Association of H2Bub1 with the chromatin of FLC clade genes depended on UBC1,2 and HUB1,2, as did the dynamics of methylated histones H3K4me3 and H3K36me2. The monoubiquitination of H2B via UBC1,2 and HUB1,2 represents a novel form of histone modification that is involved in flowering time regulation.
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Affiliation(s)
- Ying Cao
- Institute of Molecular Cellular Biology, Hebei Key Laboratory of Molecular and Cellular Biology, Hebei Normal University, Shijiazhuang 050016, China
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Doerner P. Phosphate starvation signaling: a threesome controls systemic P(i) homeostasis. Curr Opin Plant Biol 2008; 11:536-40. [PMID: 18614391 DOI: 10.1016/j.pbi.2008.05.006] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2008] [Revised: 05/27/2008] [Accepted: 05/28/2008] [Indexed: 05/03/2023]
Abstract
Systemic signaling between roots and shoots is required to maintain mineral nutrient homeostasis for optimal metabolism under varying environmental conditions. Recent work has revealed molecular components of a signaling module that controls systemic phosphate homeostasis, modulates uptake and transport in Arabidopsis. This module comprises PHO2, a protein that controls protein stability, the phloem-mobile microRNA-399 and a ribo-regulator that squelches the activity of miR399 towards PHO2 by a novel mechanism. This advance is a significant step for the design of future rational approaches to improve crop phosphate use efficiency.
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Affiliation(s)
- Peter Doerner
- Institute of Molecular Plant Science, School of Biological Sciences, Daniel Rutherford Building, King's Buildings, University of Edinburgh, Edinburgh EH9 3JH, Scotland, United Kingdom.
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Zhang Y, Feng S, Chen F, Chen H, Wang J, McCall C, Xiong Y, Deng XW. Arabidopsis DDB1-CUL4 ASSOCIATED FACTOR1 forms a nuclear E3 ubiquitin ligase with DDB1 and CUL4 that is involved in multiple plant developmental processes. Plant Cell 2008; 20:1437-55. [PMID: 18552200 PMCID: PMC2483375 DOI: 10.1105/tpc.108.058891] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2008] [Revised: 05/01/2008] [Accepted: 05/30/2008] [Indexed: 05/20/2023]
Abstract
The human DDB1-CUL4 ASSOCIATED FACTOR (DCAF) proteins have been reported to interact directly with UV-DAMAGED DNA BINDING PROTEIN1 (DDB1) through the WDxR motif in their WD40 domain and function as substrate-recognition receptors for CULLIN4-based E3 ubiquitin ligases. Here, we identified and characterized a homolog of human DCAF1/VprBP in Arabidopsis thaliana. Yeast two-hybrid analysis demonstrated the physical interaction between DCAF1 and DDB1 from Arabidopsis, which is likely mediated via the WD40 domain of DCAF1 that contains two WDxR motifs. Moreover, coimmunoprecipitation assays showed that DCAF1 associates with DDB1, RELATED TO UBIQUITIN-modified CUL4, and the COP9 signalosome in vivo but not with CULLIN-ASSOCIATED and NEDDYLATION-DISSOCIATED1, CONSTITUTIVE PHOTOMORPHOGENIC1 (COP1), or the COP10-DET1-DDB1 complex, supporting the existence of a distinct Arabidopsis CUL4 E3 ubiquitin ligase, the CUL4-DDB1-DCAF1 complex. Transient expression of fluorescently tagged DCAF1, DDB1, and CUL4 in onion epidermal cells showed their colocalization in the nucleus, consistent with the notion that the CUL4-DDB1-DCAF1 complex functions as a nuclear E3 ubiquitin ligase. Genetic and phenotypic analysis of two T-DNA insertion mutants of DCAF1 showed that embryonic development of the dcaf1 homozygote is arrested at the globular stage, indicating that DCAF1 is essential for plant embryogenesis. Reducing the levels of DCAF1 leads to diverse developmental defects, implying that DCAF1 might be involved in multiple developmental pathways.
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Affiliation(s)
- Yu Zhang
- Peking-Yale Joint Center of Plant Molecular Genetics and Agrobiotechnology, College of Life Sciences, Peking University, Beijing 100871, China
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Shimada K, Suzuki N, Ono Y, Tanaka K, Maeno M, Ito K. Ubc9 promotes the stability of Smad4 and the nuclear accumulation of Smad1 in osteoblast-like Saos-2 cells. Bone 2008; 42:886-93. [PMID: 18321803 DOI: 10.1016/j.bone.2008.01.009] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/05/2007] [Revised: 12/17/2007] [Accepted: 01/14/2008] [Indexed: 10/22/2022]
Abstract
Bone morphogenetic proteins (BMPs) play important roles in osteoblast differentiation and maturation. In mammals, the BMP-induced receptor-regulated Smads form complexes with Smad4. These complexes translocate and accumulate within the nucleus, where they regulate the transcription of various target genes. However, the function of Smad4 remains unclear. We performed a yeast two-hybrid screen using Smad4 as bait and a cDNA library derived from human bone marrow to identify the proteins interacting with Smad4. Two full-length cDNA clones for Ubc9 were identified, and the potential functions of Ubc9 were investigated. To determine the role of Ubc9 in the BMP signaling pathway, the endogenous transcription of Ubc9 in the human osteoblast cell line Saos-2 was silenced using siRNA. The expression of BMP-induced transcription factors, including Runx2, Dlx5, Msx2, and Osterix, was examined using real-time reverse transcription polymerase chain reaction (qRT-PCR), and the protein expression of Smad4, Smad1, phosphorylated Smad1, and BMP type I receptors was determined by Western blotting. The subcellular localization of Smad1 and Smad4 was observed using immunofluorescence staining after Ubc9 silencing. To determine whether Smad4 is sumoylated in vitro, recombinant Smad4 was purified and sumoylated Smad4 was visualized using Western blotting. The mRNA expression of various transcription factors was markedly inhibited after Ubc9 silencing. The protein levels of Smad4 and phosphorylated Smad1 decreased in a dose-dependent manner according to the amount of siRNA applied. Gene silencing also decreased the nuclear accumulation of Smad1 and Smad4. The sumoylation assay showed that sumoylated Smad4 is present and dependent on Ubc9 in vitro, which was confirmed by pretreatment with Senp2, a SUMO-protease. These results suggest that Ubc9 promotes the stability of sumoylated Smad4. Furthermore, the expression of key transcription factors, phosphorylated Smad1 protein, and the nuclear accumulation of Smad1 and Smad4 are inhibited by Ubc9 silencing. Thus, Ubc9 plays an important role in the up-regulation of the BMP signaling pathway.
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Affiliation(s)
- Koichi Shimada
- Department of Periodontology, Nihon University School of Dentistry, 1-8-13 Kanda-Surugadai, Chiyoda-ku, Tokyo 101-8310, Japan.
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Kobayashi J, Iwabuchi K, Miyagawa K, Sonoda E, Suzuki K, Takata M, Tauchi H. Current topics in DNA double-strand break repair. J Radiat Res 2008; 49:93-103. [PMID: 18285658 DOI: 10.1269/jrr.07130] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
DNA double strand break (DSB) is one of the most critical types of damage which is induced by ionizing radiation. In this review, we summarize current progress in investigations on the function of DSB repair-related proteins. We focused on recent findings in the analysis of the function of proteins such as 53BP1, histone H2AX, Mus81-Eme1, Fanc complex, and UBC13, which are found to be related to homologous recombination repair or to non-homologous end joining. In addition to the function of these proteins in DSB repair, the biological function of nuclear foci formation following DSB induction is discussed.
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Affiliation(s)
- Junya Kobayashi
- Department of Genome Repair Dynamics, Radiation Biology Center, Kyoto University, Kyoto, Japan
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Hishida T. [Molecular mechanisms of RAD6 DNA damage tolerance pathway in Saccharomyces cerevisiae]. Seikagaku 2008; 80:124-128. [PMID: 18341033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Affiliation(s)
- Takashi Hishida
- Research Institute for Microbial Diseases, Osaka University, 3-1 Yamadaoka, Suita, Osaka 565-0871, Japan
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Shiratori T, Shimada H, Kagaya A, Kuboshima M, Nabeya Y, Machida T, Goto KI, Takiguchi M, Ochiai T, Hiwasa T. Sensitization against anticancer drugs by transfection with UBE2I variant gene into ras-NIH3H3 mouse fibroblasts. Anticancer Res 2007; 27:3227-3233. [PMID: 17970065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
We previously performed SEREX (serological identification of antigens by recombinant expression cloning) using the sera of patients with esophageal squamous cell carcinoma (SCC), and isolated a variant clone (AK093616) of ubiquitin-conjugating enzyme E21 (UBE2I). This clone was tentatively designated as UBE2I-v5 and analyzed for biological function by transient transfection of the cDNA into activated Ha-ras-transformed NIH3T3 (ras-NIH) mouse fibroblasts. Chemosensitivity to 92 cytotoxic drugs was compared between UBE2I-v5-transfected cells and the parental ras-NIH cells. The UBE2I-v5-transfected cells were more sensitive than the parental cells to anticancer drugs such as vincristine (VCR), mitoxantrone (MIT) and etoposide (VP16). The regression analysis of the total chemosensitivity pattern of UBE2I-vS-transfected cells revealed that the function of UBE2I-v5 was positively related to RPA2 (replication protein A2), Rho-GDI (Rho guanine nucleotide dissociation inhibitor a), FUS (putative tumor suppressor) and TKT (transketolase) but negatively related to Per-1 (period-I), Ran (nuclear Ras-related protein), PTEN (phosphatase and tensin homolog), C/EBPalpha (CCAAT/enhancer binding protein a) and the tumor suppressor p53. Thus, it is possible that UBE21-v5 plays a role in carcinogenesis by suppressing the function of CIEBPa and/or p53 via RPA2-like activity.
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Affiliation(s)
- Tooru Shiratori
- Departments of Frontier Surgery, Graduate School of Medicine, Chiba University, Inohana 1-8-1, Chuo-ku, Chiba, Japan
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Petroski MD, Zhou X, Dong G, Daniel-Issakani S, Payan DG, Huang J. Substrate modification with lysine 63-linked ubiquitin chains through the UBC13-UEV1A ubiquitin-conjugating enzyme. J Biol Chem 2007; 282:29936-45. [PMID: 17709375 DOI: 10.1074/jbc.m703911200] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Protein modification with lysine 63-linked ubiquitin chains has been implicated in the non-proteolytic regulation of signaling pathways. To understand the molecular mechanisms underlying this process, we have developed an in vitro system to examine the activity of the ubiquitin-conjugating enzyme UBC13-UEV1A with TRAF6 in which TRAF6 serves as both a ubiquitin ligase and substrate for modification. Although TRAF6 potently stimulates the activity of UBC13-UEV1A to synthesize ubiquitin chains, it is not appreciably ubiquitinated. We have determined that the presentation of Lys(63) of ubiquitin by UEV1A suppresses TRAF6 modification. Based on our observations, we propose that the modification of proteins with Lys(63)-linked ubiquitin chains occurs through a UEV1A-independent substrate modification and UEV1A-dependent Lys(63)-linked ubiquitin chain synthesis mechanism.
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Affiliation(s)
- Matthew D Petroski
- Rigel Pharmaceuticals, Inc., South San Francisco, California 94080, USA.
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36
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Yan J, Yang XP, Kim YS, Joo JH, Jetten AM. RAP80 interacts with the SUMO-conjugating enzyme UBC9 and is a novel target for sumoylation. Biochem Biophys Res Commun 2007; 362:132-138. [PMID: 17698038 PMCID: PMC2049087 DOI: 10.1016/j.bbrc.2007.07.158] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2007] [Accepted: 07/30/2007] [Indexed: 11/21/2022]
Abstract
RAP80, a nuclear protein with two functional ubiquitin-interaction motifs (UIMs) at its N-terminus, plays a critical role in the regulation of estrogen receptor alpha and DNA damage response signaling. A yeast two-hybrid screen identified the SUMO-conjugating enzyme UBC9 as a protein interacting with RAP80. The interaction of RAP80 with UBC9 was confirmed by co-immunoprecipitation and GST pull-down analyses. The region between aa 122-204 was critical for the interaction of RAP80 with UBC9. In addition, we demonstrate that RAP80 is a target for SUMO-1 modification in intact cells. Expression of UBC9 enhanced RAP80 mono-sumoylation and also induced multi-sumoylation of RAP80. In addition to SUMO-1, RAP80 was efficiently conjugated to SUMO-3 but was only a weak substrate for SUMO-2 conjugation. These findings suggest that sumoylation plays a role in the regulation of RAP80 functions.
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Affiliation(s)
- Jun Yan
- Cell Biology Section, Division of Intramural Research, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA
| | - Xiao-Ping Yang
- Cell Biology Section, Division of Intramural Research, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA
| | - Yong-Sik Kim
- Cell Biology Section, Division of Intramural Research, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA
| | - Joung Hyuck Joo
- Cell Biology Section, Division of Intramural Research, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA
| | - Anton M Jetten
- Cell Biology Section, Division of Intramural Research, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA.
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Banerjee S, Brooks WS, Crawford DF. Inactivation of the ubiquitin conjugating enzyme UBE2Q2 causes a prophase arrest and enhanced apoptosis in response to microtubule inhibiting agents. Oncogene 2007; 26:6509-17. [PMID: 17471241 DOI: 10.1038/sj.onc.1210471] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
A putative ubiquitin conjugating enzyme known as UBE2Q2 was previously identified in a microarray screen for mitotic regulatory proteins. UBE2Q2 is very similar to another human protein, UBE2Q1 and orthologs from other higher eukaryotic species. In these studies, we demonstrate that UBE2Q2 can covalently bind ubiquitin on the active site cysteine in vitro and show that inhibition of this protein in vivo causes an early mitotic arrest and increased cytotoxicity when cells are treated with microtubule inhibiting agents (MIAs). Changes in cell cycle progression and viability are not observed in the absence of MIA treatment, indicating that UBE2Q2 is involved in the response to MIAs rather than performing a more general function in mitosis. Inhibition of the UBE2Q2 protein causes cells to undergo a prolonged prophase arrest suggesting that UBE2Q2 normally functions to antagonize an early mitotic checkpoint. Furthermore, UBE2Q2 inhibition sensitizes cells to the cytotoxic effects of MIAs through caspase-mediated apoptosis that is correlated with PARP-1 cleavage. These data provide insights into the cellular response to MIAs and demonstrate that inhibition of UBE2Q2 protein function may be useful in the treatment of malignancies.
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Affiliation(s)
- S Banerjee
- Department of Pediatrics, University of Alabama, Birmingham 35233, USA
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38
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Capili AD, Lima CD. Structure and analysis of a complex between SUMO and Ubc9 illustrates features of a conserved E2-Ubl interaction. J Mol Biol 2007; 369:608-18. [PMID: 17466333 PMCID: PMC1940065 DOI: 10.1016/j.jmb.2007.04.006] [Citation(s) in RCA: 116] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2007] [Revised: 03/23/2007] [Accepted: 04/01/2007] [Indexed: 11/21/2022]
Abstract
The SUMO E2 Ubc9 serves as a lynchpin in the SUMO conjugation pathway, interacting with the SUMO E1 during activation, with thioester linked SUMO after E1 transfer and with the substrate and SUMO E3 ligases during conjugation. Here, we describe the structure determination of a non-covalent complex between human Ubc9 and SUMO-1 at 2.4 A resolution. Non-covalent interactions between Ubc9 and SUMO are conserved in human and yeast insomuch as human Ubc9 interacts with each of the human SUMO isoforms, and yeast Ubc9 interacts with Smt3, the yeast SUMO ortholog. Structural comparisons reveal similarities to several other non-covalent complexes in the ubiquitin pathway, suggesting that the non-covalent Ubc9-SUMO interface may be important for poly-SUMO chain formation, for E2 recruitment to SUMO conjugated substrates, or for mediating E2 interactions with either E1 or E3 ligases. Biochemical analysis suggests that this surface is less important for E1 activation or di-SUMO-2 formation, but more important for E3 interactions and for poly-SUMO chain formation when the chain exceeds more than two SUMO proteins.
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Affiliation(s)
| | - Christopher D. Lima
- *To whom correspondence should be addressed. , Ph: (212) 639-8205, FAX: (212) 717-3047
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Lin J, Raoof DA, Wang Z, Lin MY, Thomas DG, Greenson JK, Giordano TJ, Orringer MB, Chang AC, Beer DG, Lin L. Expression and effect of inhibition of the ubiquitin-conjugating enzyme E2C on esophageal adenocarcinoma. Neoplasia 2007; 8:1062-71. [PMID: 17217624 PMCID: PMC1783715 DOI: 10.1593/neo.05832] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Ubiquitin-dependent proteolysis of cyclins plays a critical role in cell cycle progression and tumorigenesis. We examined the expression of ubiquitin-conjugating enzyme E2C (UBE2C) during progression from Barrett's metaplasia to esophageal adenocarcinoma (EA) and the effects of targeting this enzyme on EA-derived cell lines. Using oligonucleotide microarrays UBE2C expression was elevated in 73% (11 of 15) of EAs relative to Barrett's metaplasia. Tissue microarray showed elevated UBE2C in 70% (7 of 10) of dysplastic samples and in 87% (58 of 67) of tumors relative to metaplastic samples. Transfection of dominant-negative UBE2C into Seg-1 cells decreased proliferation (P = .04) and increased mitotic arrest compared to vector controls (63.5% vs 6.8%; P < .001). Transfection of UBE2C small interfering RNA also caused inhibiton of cell proliferation and distortion of the cell cycle, with maximal increase of G(2) cells (155% of mock cells) at 72 hours and of S-phase cells (308% of mock cells) at 24 hours. Treatment of Seg-1 cells with the proteasome inhibitor MG-262 (1 nM-1 microM) showed decreased proliferation (P = .02). EA-derived cells expressing UBE2C are sensitive to treatment with MG-262 and to silencing of UBE2C, suggesting that patients with EAs overexpressing UBE2C may benefit from agents targeting this ubiquitin-conjugating enzyme.
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Affiliation(s)
- Jules Lin
- Section of General Thoracic Surgery, Department of Surgery, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Duna A Raoof
- Section of General Thoracic Surgery, Department of Surgery, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Zhuwen Wang
- Section of General Thoracic Surgery, Department of Surgery, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Mu-Yen Lin
- Division of Thoracic Surgery, Department of Surgery and Institute of Clinical Medicine, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Dafydd G Thomas
- Department of Pathology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Joel K Greenson
- Department of Pathology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Thomas J Giordano
- Department of Pathology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Mark B Orringer
- Section of General Thoracic Surgery, Department of Surgery, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Andrew C Chang
- Section of General Thoracic Surgery, Department of Surgery, University of Michigan Medical School, Ann Arbor, MI, USA
| | - David G Beer
- Section of General Thoracic Surgery, Department of Surgery, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Lin Lin
- Section of General Thoracic Surgery, Department of Surgery, University of Michigan Medical School, Ann Arbor, MI, USA
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Yokota K, Shibata H, Kurihara I, Kobayashi S, Suda N, Murai-Takeda A, Saito I, Kitagawa H, Kato S, Saruta T, Itoh H. Coactivation of the N-terminal Transactivation of Mineralocorticoid Receptor by Ubc9. J Biol Chem 2007; 282:1998-2010. [PMID: 17105732 DOI: 10.1074/jbc.m607741200] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Molecular mechanisms underlying mineralocorticoid receptor (MR)-mediated gene expression are not fully understood. Various transcription factors are post-translationally modified by small ubiquitin-related modifier-1 (SUMO-1). We investigated the role of the SUMO-1-conjugating enzyme Ubc9 in MR transactivation. Yeast two-hybrid, GST-pulldown, and coimmunoprecipitation assays showed that Ubc9 interacted with N-terminal MR-(1-670). Endogenous Ubc9 is associated with stably expressing MR in 293-MR cells. Transient transfection assays in COS-1 cells showed that Ubc9 increased MR transactivation of reporter constructs containing MRE, ENaC, or MMTV promoter in a hormone-sensitive manner. Moreover, reduction of Ubc9 protein levels by small interfering RNA attenuated hormonal activation of a reporter construct as well as an endogenous target gene by MR. A sumoylation-inactive mutant Ubc9(C93S) similarly interacted with MR and potentiated aldosterone-dependent MR transactivation. An MR mutant in which four lysine residues within sumoylation motifs were mutated into arginine (K89R/K399R/K494R/K953R) failed to be sumoylated, but Ubc9 similarly enhanced transactivation by the mutant MR, indicating that sumoylation activity is dispensable for coactivation capacity of Ubc9. Coexpression of Ubc9 and steroid receptor coactivator-1 (SRC-1) synergistically enhanced MR-mediated transactivation in transient transfection assays. Indeed, chromatin immunoprecipitation assays demonstrated that endogenous MR, Ubc9, and SRC-1 were recruited to an endogenous ENaC gene promoter in a largely aldosterone-dependent manner. Coimmunoprecipitation assays showed a complex of MR, Ubc9, and SRC-1 in mammalian cells, and the endogenous proteins were colocalized in the nuclei of the mouse collecting duct cells. These findings support a physiological role of Ubc9 as a transcriptional MR coactivator, beyond the known SUMO E2-conjugating enzyme.
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Affiliation(s)
- Kenichi Yokota
- Department of Internal Medicine, School of Medicine, Keio University, Tokyo, Japan
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41
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Lamothe B, Besse A, Campos AD, Webster WK, Wu H, Darnay BG. Site-specific Lys-63-linked tumor necrosis factor receptor-associated factor 6 auto-ubiquitination is a critical determinant of I kappa B kinase activation. J Biol Chem 2006; 282:4102-12. [PMID: 17135271 PMCID: PMC3221607 DOI: 10.1074/jbc.m609503200] [Citation(s) in RCA: 295] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Tumor necrosis factor (TNF) receptor-associated factor 6 (TRAF6) is a key mediator in proximal signaling of the interleukin-1/Toll-like receptor and the TNF receptor superfamily. Analysis of TRAF6-deficient mice revealed a fundamental role of TRAF6 in osteoclastogenesis; however, the molecular mechanism underlying TRAF6 signaling in this biological process is not understood. Recent biochemical evidence has indicated that TRAF6 possesses ubiquitin ligase activity that controls the activation of IKK and NF-kappaB. Because these studies are primarily based on cell-free systems, the role of the ubiquitin ligase activity of TRAF6 and its auto-ubiquitination to initiate the NF-kappaB pathway in vivo remain elusive. Here we show that an intact RING domain of TRAF6 in conjunction with the E2 enzyme Ubc13/Uev1A is necessary for Lys-63-linked auto-ubiquitination of TRAF6 and for its ability to activate IKK and NF-kappaB. Furthermore, a RING mutant of TRAF6 abolishes its ability to induce receptor activator of NF-kappaB-independent osteoclast differentiation and nuclear accumulation of the transcription factor NFATc1. Notably, we map the auto-ubiquitination site of TRAF6 to a single Lys residue, which if mutated renders TRAF6 unable to activate transforming growth factor-beta-activated kinase 1 and IKK and to cause spontaneous osteoclast differentiation. Additionally, we provide biochemical and in vivo evidence that TRAF6 serves as an E3 to directly ubiquitinate NEMO. Reconstituting TRAF6-deficent cells with various TRAF6 mutants, we clearly demonstrate the requirement for the TRAF6 RING domain and site-specific auto-ubiquitination of TRAF6 to activate IKK in response to interleukin-1. These data establish a signaling cascade in which regulated site-specific Lys-63-linked TRAF6 auto-ubiquitination is the critical upstream mediator of IKK.
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Affiliation(s)
- Betty Lamothe
- Department of Experimental Therapeutics, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030
| | - Arnaud Besse
- Department of Experimental Therapeutics, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030
| | - Alejandro D. Campos
- Department of Experimental Therapeutics, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030
| | - William K. Webster
- Department of Experimental Therapeutics, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030
| | - Hao Wu
- Department of Biochemistry, Weill Medical College of Cornell University, New York, NY 10021
| | - Bryant G. Darnay
- Department of Experimental Therapeutics, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030
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42
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Sakata E, Kato K. [Structural aspects of the ubiquitin system]. Tanpakushitsu Kakusan Koso 2006; 51:1134-42. [PMID: 16922365] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
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43
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Matsumoto M. [Involvement of ubiquitin-proteasome system in polyglutamine disease]. Tanpakushitsu Kakusan Koso 2006; 51:1428-32. [PMID: 16922413] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
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44
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Matsuda N. [Diversity of E3: A brief sketch from their motifs]. Tanpakushitsu Kakusan Koso 2006; 51:1157-62. [PMID: 16922368] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
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45
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Tokunaga F. [E2 ubiquitin-conjugating enzymes: structures and functions]. Tanpakushitsu Kakusan Koso 2006; 51:1150-6. [PMID: 16922367] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
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46
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Kanayama A, Inoue JI. [Ubiquitin-dependent regulation of the NFkappaB signaling]. Tanpakushitsu Kakusan Koso 2006; 51:1266-70. [PMID: 16922385] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
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47
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Abstract
E2-EPF ubiquitin carrier protein (UCP) is a member of an E2 family of enzymes that catalyzes the ligation of ubiquitin to proteins targeted for destruction by the proteasome. UCP is overexpressed in common human cancers, suggesting its involvement in oncogenesis, but a physiologic target of UCP has not been identified. In a recent report published in Nature Medicine, Jung et al. identified von Hippel-Lindau (VHL) tumor suppressor protein, which targets the alpha subunit of hypoxia-inducible factor (HIF) for ubiquitin-mediated destruction, as a bona fide substrate of UCP and demonstrated a potential pVHL-HIF pathway-dependent role for UCP in cancer development.
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Affiliation(s)
- Michael Ohh
- Department of Laboratory Medicine and Pathobiology, University of Toronto, 1 King's College Circle, Toronto, Ontario M5S 1A8, Canada.
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48
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Takeda K, Yanagida M. [How does fission yeast cut8 regulate the nuclear localization of proteasome?]. Tanpakushitsu Kakusan Koso 2006; 51:1241-4. [PMID: 16922381] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
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49
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Abstract
Somatic hypermutation of Ig genes is initiated by transcription-coupled cytidine deamination in Ig loci. Error-prone processing of the resultant DNA lesions is thought to cause extensive mutagenesis, but it is presently an enigma how and why error-prone rather than error-free repair pathways are recruited. During DNA replication, recruitment of error-prone translesion polymerases may be mediated by Rad6/Rad18-mediated ubiquitination of proliferating cell nuclear antigen, a major switchboard controlling the fidelity of DNA lesion bypass in eukaryotes. By inactivation of Rad18 in the DT40 B cell line, we show that the Rad6 pathway is involved in somatic hypermutation in these cells. Our findings imply that targeted recruitment of mutagenic polymerases by the Rad6 pathway contributes to the complex process of somatic hypermutation and provide a framework for more detailed mechanistic studies of the mutagenesis phase of secondary Ig diversification.
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Affiliation(s)
- Jürgen Bachl
- Institute of Clinical Molecular Biology and Tumor Genetics, GSF-Research Center for Environment and Health, Marchioninistrasse 25, 81377 Munich, Germany
| | - Isin Ertongur
- Institute of Clinical Molecular Biology and Tumor Genetics, GSF-Research Center for Environment and Health, Marchioninistrasse 25, 81377 Munich, Germany
| | - Berit Jungnickel
- Institute of Clinical Molecular Biology and Tumor Genetics, GSF-Research Center for Environment and Health, Marchioninistrasse 25, 81377 Munich, Germany
- *To whom correspondence should be addressed. E-mail:
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50
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Yamamoto M, Okamoto T, Takeda K, Sato S, Sanjo H, Uematsu S, Saitoh T, Yamamoto N, Sakurai H, Ishii KJ, Yamaoka S, Kawai T, Matsuura Y, Takeuchi O, Akira S. Key function for the Ubc13 E2 ubiquitin-conjugating enzyme in immune receptor signaling. Nat Immunol 2006; 7:962-70. [PMID: 16862162 DOI: 10.1038/ni1367] [Citation(s) in RCA: 215] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2006] [Accepted: 06/29/2006] [Indexed: 11/09/2022]
Abstract
The Ubc13 E2 ubiquitin-conjugating enzyme is key in the process of 'tagging' target proteins with lysine 63-linked polyubiquitin chains, which are essential for the transmission of immune receptor signals culminating in activation of the transcription factor NF-kappaB. Here we demonstrate that conditional ablation of Ubc13 resulted in defective B cell development and in impaired B cell and macrophage activation. In response to all tested stimuli except tumor necrosis factor, Ubc13-deficient cells showed almost normal NF-kappaB activation but considerably impaired activation of mitogen-activated protein kinase. Ubc13-induced activation of mitogen-activated protein kinase required, at least in part, ubiquitination of the adaptor protein IKKgamma. These results show that Ubc13 is key in the mammalian immune response.
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Affiliation(s)
- Masahiro Yamamoto
- Department of Host Defense, Research Institute for Microbial Diseases, Osaka University, Osaka 565-0871, Japan
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