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Shukla PK, Sinha D, Leng AM, Bissell JE, Thatipamula S, Ganguly R, Radmall KS, Skalicky JJ, Shrieve DC, Chandrasekharan MB. Mutations of Rad6 E2 ubiquitin-conjugating enzymes at alanine-126 affect ubiquitination activity and decrease enzyme stability. J Biol Chem 2022; 298:102524. [PMID: 36162503 PMCID: PMC9630792 DOI: 10.1016/j.jbc.2022.102524] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2022] [Revised: 09/16/2022] [Accepted: 09/17/2022] [Indexed: 11/28/2022] Open
Abstract
Rad6, an E2 ubiquitin-conjugating enzyme conserved from yeast to humans, functions in transcription, genome maintenance, and proteostasis. The contributions of many conserved secondary structures of Rad6 and its human homologs UBE2A and UBE2B to their biological functions are not understood. A mutant RAD6 allele with a missense substitution at alanine-126 (A126) of helix-3 that causes defects in telomeric gene silencing, DNA repair, and protein degradation was reported over 2 decades ago. Here, using a combination of genetics, biochemical, biophysical, and computational approaches, we discovered that helix-3 A126 mutations compromise the ability of Rad6 to ubiquitinate target proteins without disrupting interactions with partner E3 ubiquitin-ligases that are required for their various biological functions in vivo. Explaining the defective in vitro or in vivo ubiquitination activities, molecular dynamics simulations and NMR showed that helix-3 A126 mutations cause local disorder of the catalytic pocket of Rad6 in addition to disorganizing the global structure of the protein to decrease its stability in vivo. We also show that helix-3 A126 mutations deform the structures of UBE2A and UBE2B, the human Rad6 homologs, and compromise the in vitro ubiquitination activity and folding of UBE2B. Providing insights into their ubiquitination defects, we determined helix-3 A126 mutations impair the initial ubiquitin charging and the final discharging steps during substrate ubiquitination by Rad6. In summary, our studies reveal that the conserved helix-3 is a crucial structural constituent that controls the organization of catalytic pockets, enzymatic activities, and biological functions of the Rad6-family E2 ubiquitin-conjugating enzymes.
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Affiliation(s)
- Prakash K Shukla
- Department of Radiation Oncology and Huntsman Cancer Institute, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Dhiraj Sinha
- IHU, Aix Marseille University, Marseille, France
| | - Andrew M Leng
- Department of Radiation Oncology and Huntsman Cancer Institute, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Jesse E Bissell
- Department of Radiation Oncology and Huntsman Cancer Institute, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Shravya Thatipamula
- Department of Radiation Oncology and Huntsman Cancer Institute, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Rajarshi Ganguly
- Department of Radiation Oncology and Huntsman Cancer Institute, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Kaitlin S Radmall
- Department of Radiation Oncology and Huntsman Cancer Institute, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Jack J Skalicky
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Dennis C Shrieve
- Department of Radiation Oncology and Huntsman Cancer Institute, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Mahesh B Chandrasekharan
- Department of Radiation Oncology and Huntsman Cancer Institute, University of Utah School of Medicine, Salt Lake City, UT 84112, USA.
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Abstract
Ubiquitin-conjugating enzyme E2 B (UBE2B) can form a heterodimer with ubiquitin E3 ligase RAD18. In this study, we aimed to explore new substrates of the UBE2B/RAD18 complex and their regulatory effects in ovarian cancer. Protein physical interactions were predicted using GeneMANIA. Serial sections of commercial ovarian cancer tissue arrays were used to check the protein expression of UBE2B, RAD18, and ZMYM2. Immunofluorescence staining and co-immunoprecipitation assays were performed to check their location and interactions. Cycloheximide chase assay was applied to explore the influence of UBE2B and RAD18 on ZMYM2 degradation. Xenograft tumor models were constructed to assess the influence of the UBE2B-ZMYM2 axis on in vivo tumor growth. A strong positive correlation between UBE2B and ZMYM2 and a moderate positive correlation between RAD18 and ZMYM2 were observed in 23 ovarian cancer cases. In CAOV4 and OVCAR3 cells, myc-ZMYM2 interacted with UBE2B and RAD18. UBE2B and ZMYM2 could be detected in the samples immunoprecipitated by anti-RAD18. UBE2B overexpression or knockdown did not alter ZMYM2 mRNA expression. UBE2B overexpression increased ZMYM2 monoubiquitination but reduced its polyubiquitination. RAD18 knockdown impaired UBE2B-induced ZMYM2 monoubiquitination. UBE2B overexpression significantly enhanced the stability of ZMYM2 protein, the effect of which was weakened by RAD18 knockdown. UBE2B overexpression significantly enhanced the growth of xenograft tumors derived from CAOV4 cells. ZMYM2 knockdown remarkedly suppressed tumor growth and impaired the growth-promoting effect of UBE2B overexpression. In conclusion, this study revealed a novel regulatory effect of the UBE2B/RAD18 complex on ZMYM2 monoubiquitination and stability in ovarian cancer.
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Affiliation(s)
- Xi Zeng
- Department of Obstetrics & Gynecology, Key Laboratory of Birth Defects and Related Diseases of Women and Children, Ministry of Education, West China Second University Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Wen Zheng
- Laboratory of Clinical Proteomics and Metabolomics, Institutes for Systems Genetics, Frontiers Science Center for Disease-related Molecular Network, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Yuting Sheng
- Department of Obstetrics & Gynecology, Key Laboratory of Birth Defects and Related Diseases of Women and Children, Ministry of Education, West China Second University Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Hongwei Ma
- Department of Obstetrics & Gynecology, Key Laboratory of Birth Defects and Related Diseases of Women and Children, Ministry of Education, West China Second University Hospital, Sichuan University, Chengdu, Sichuan, China
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Huang WL, Luo CW, Chou CL, Yang CC, Chen TJ, Li CF, Pan MR. High Expression of UBE2B as a Poor Prognosis Factor in Patients With Rectal Cancer Following Chemoradiotherapy. Anticancer Res 2020; 40:6305-6317. [PMID: 33109568 DOI: 10.21873/anticanres.14651] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Revised: 09/22/2020] [Accepted: 09/24/2020] [Indexed: 11/10/2022]
Abstract
BACKGROUND/AIM Neoadjuvant concurrent chemoradiotherapy (CCRT) is the standard therapeutic strategy for rectal cancer. However, 15-20% of patients undergoing neoadjuvant CCRT progress to recurrence or distant metastases. Therefore, identifying a predictive biomarker is necessary for treating CCRT. MATERIALS AND METHODS We investigated the relationship between the levels of histone ubiquitination enzyme and clinicopathological outcomes in patients with rectal cancer who were administered CCRT and confirm the role of histone ubiquitination enzyme in regulating the cell response to ionizing radiation (IR). RESULTS Clinical data indicated that UBE2B expression was significantly correlated with tumor regression grade. Inhibition of UBE2B elevated the genotoxicity of IR to radioresistant cell lines. In contrast, UBE2B over-expression reduced cell sensitivity to IR. Importantly, the recruitment of 53BP1 and Rad51 was remarkably prolonged in cells after pre-treatment with UBE2B inhibitor, TZ9, suggesting a defective DNA repair pathway in UBE2B-deficient cells. CONCLUSION These results indicate that over-expression of UBE2B correlates with poor response and low survival rate in patients who are administered preoperative CCRT.
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Affiliation(s)
- Wei-Lun Huang
- Graduate Institute of Clinical Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan, R.O.C.,Department of Radiation oncology, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan, R.O.C
| | - Chi-Wen Luo
- Division of Breast Surgery, Department of Surgery, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan, R.O.C
| | - Chia-Lin Chou
- Division of Colon & Rectal Surgery, Department of Surgery, Chi Mei Medical Center, Tainan, Taiwan, R.O.C.,Institute of Biomedical Sciences, National Sun Yat-Sen University, Kaohsiung, Taiwan, R.O.C
| | - Ching-Chieh Yang
- Department of Radiation Oncology, Chi-Mei Medical Center, Tainan, Taiwan, R.O.C.,Department of Pharmacy, Chia-Nan University of Pharmacy and Science, Tainan, Taiwan, R.O.C
| | - Tzu-Ju Chen
- Department of Pharmacy, Chia-Nan University of Pharmacy and Science, Tainan, Taiwan, R.O.C.,Department of Pathology, Chi Mei Medical Center, Tainan, Taiwan, R.O.C.,Department of Optometry, Chung Hwa University of Medical Technology, Tainan, Taiwan, R.O.C
| | - Chien-Feng Li
- Department of Pathology, Chi Mei Medical Center, Tainan, Taiwan, R.O.C.,Department of Medical Research, Chi Mei Medical Center, Tainan, Taiwan, R.O.C.,National Institute of Cancer Research, National Health Research Institute, Tainan, Taiwan, R.O.C
| | - Mei-Ren Pan
- Graduate Institute of Clinical Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan, R.O.C. .,Drug Development and Value Creation Research Center, Kaohsiung Medical University, Kaohsiung, Taiwan, R.O.C
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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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Cheng CM, Shiah SG, Huang CC, Hsiao JR, Chang JY. Up-regulation of miR-455-5p by the TGF-β-SMAD signalling axis promotes the proliferation of oral squamous cancer cells by targeting UBE2B. J Pathol 2016; 240:38-49. [PMID: 27235675 DOI: 10.1002/path.4752] [Citation(s) in RCA: 70] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Revised: 03/31/2016] [Accepted: 05/14/2016] [Indexed: 01/07/2023]
Abstract
MicroRNAs (miRNAs) are involved in the tumourigenesis of various cancers by regulating their downstream targets. To identify the changes of miRNAs in oral squamous cell carcinoma (OSCC), we investigated the expression profiles of miRNAs in 40 pairs of OSCC specimens and their matched non-tumour epithelial tissues. Our data revealed higher miR-455-5p expression in the tumour tissues than in the normal tissues; the expression was also higher in oral cancer cell lines than in normal keratinocyte cell lines. MiR-455-5p knockdown reduced both the anchorage-independent growth and the proliferative ability of oral cancer cells, and these factors increased in miR-455-5p-overexpressing cells. Furthermore, by analysing the array data of patients with cancer and cell lines, we identified ubiquitin-conjugating enzyme E2B (UBE2B) as a target of miR-455-5p, and further validated this using 3'-untranslated region luciferase reporter assays and western blot analysis. We also demonstrated that UBE2B suppression rescued the impaired growth ability of miR-455-5p-knockdown cells. Furthermore, we observed that miR-455-5p expression was regulated, at least in part, by the transforming growth factor-β (TGF-β) pathway through the binding of SMAD3 to specific promoter regions. Notably, miR-455-5p expression was associated with the nodal status, stage, and overall survival in our patients, suggesting that miR-455-5p is a potential marker for predicting the prognosis of patients with oral cancer. In conclusion, we reveal that miR-455-5p expression is regulated by the TGF-β-dependent pathway, which subsequently leads to UBE2B down-regulation and contributes to oral cancer tumourigenesis. Copyright © 2016 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
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Affiliation(s)
- Chao-Min Cheng
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan, ROC.,National Institute of Cancer Research, National Health Research Institutes, Tainan, Taiwan, ROC
| | - Shine-Gwo Shiah
- National Institute of Cancer Research, National Health Research Institutes, Tainan, Taiwan, ROC
| | - Chien-Chang Huang
- National Institute of Cancer Research, National Health Research Institutes, Tainan, Taiwan, ROC
| | - Jenn-Ren Hsiao
- Department of Otolaryngology, Head and Neck Collaborative Oncology Group, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan, ROC
| | - Jang-Yang Chang
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan, ROC.,National Institute of Cancer Research, National Health Research Institutes, Tainan, Taiwan, ROC.,Division of Hematology/Oncology, Department of Internal Medicine, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan, ROC
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