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Zhao X, Zhong C, Zhu R, Gong R, Liu B, He L, Tian S, Jin J, Jiang T, Chen JL, Wan X, Liu W, Jiang S, Deng P, Cheng Y, Ye N. Structure-Activity Relationship Studies of Substituted 2-Phenyl-1,2,4-triazine-3,5(2 H,4 H)-dione Analogues: Development of Potent eEF2K Degraders against Triple-Negative Breast Cancer. J Med Chem 2024; 67:15837-15861. [PMID: 39208364 DOI: 10.1021/acs.jmedchem.4c01484] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/04/2024]
Abstract
eEF2K, an atypical alpha-kinase, is responsible for regulating protein synthesis and energy homeostasis. Aberrant eEF2K function has been linked to various human cancers, including triple-negative breast cancer (TNBC). However, limited cellular activity of current eEF2K modulators impedes their clinical application. Based on the 2-phenyl-1,2,4-triazine-3,5(2H,4H)-dione scaffold of our hits I4 and C1, structure-activity relationship analysis led to the discovery of several more active derivatives (e.g., 19, 34, and 36) in inhibiting the viability of TNBC cell line MDA-MB-231. Moreover, the most potent compound 36 significantly suppresses the viability, proliferation, and migration of both MDA-MB-231 and HCC1806 cell lines. Mechanistically, compound 36 has a high binding affinity for the eEF2K protein and effectively induces its degradation. Additionally, 36 exerts a comparable tumor-suppressive effect to paclitaxel in an MDA-MB-231 cell xenograft mouse model with no obvious toxicity, demonstrating that compound 36 could be developed as a potential novel therapeutic for TNBC treatment.
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Affiliation(s)
- Xiaobao Zhao
- Department of Medicinal Chemistry, Jiangsu Key Laboratory of Neuropsychiatric Diseases and College of Pharmaceutical Sciences, Soochow University, Suzhou 215123, China
| | - Changxin Zhong
- Department of Pharmacy, The Second Xiangya Hospital, Central South University, Changsha 410011, China
- Hunan Provincial Engineering Research Centre of Translational Medicine and Innovative Drug, Changsha 410011, China
| | - Rongfeng Zhu
- Department of Medicinal Chemistry, Jiangsu Key Laboratory of Neuropsychiatric Diseases and College of Pharmaceutical Sciences, Soochow University, Suzhou 215123, China
| | - Rong Gong
- Department of Pharmacy, The Second Xiangya Hospital, Central South University, Changsha 410011, China
- Hunan Provincial Engineering Research Centre of Translational Medicine and Innovative Drug, Changsha 410011, China
| | - Bingyan Liu
- Department of Medicinal Chemistry, Jiangsu Key Laboratory of Neuropsychiatric Diseases and College of Pharmaceutical Sciences, Soochow University, Suzhou 215123, China
| | - Linhao He
- Department of Pharmacy, The Second Xiangya Hospital, Central South University, Changsha 410011, China
- Hunan Provincial Engineering Research Centre of Translational Medicine and Innovative Drug, Changsha 410011, China
| | - Sheng Tian
- Department of Medicinal Chemistry, Jiangsu Key Laboratory of Neuropsychiatric Diseases and College of Pharmaceutical Sciences, Soochow University, Suzhou 215123, China
- Jiangsu Province Engineering Research Center of Precision Diagnostics and Therapeutics Development, Soochow University, Suzhou 215123, China
| | - Jing Jin
- Department of Medicinal Chemistry, Jiangsu Key Laboratory of Neuropsychiatric Diseases and College of Pharmaceutical Sciences, Soochow University, Suzhou 215123, China
| | - Ting Jiang
- Department of Pharmacy, The Second Xiangya Hospital, Central South University, Changsha 410011, China
- Hunan Provincial Engineering Research Centre of Translational Medicine and Innovative Drug, Changsha 410011, China
| | - Jing-Lei Chen
- Department of Medicinal Chemistry, Jiangsu Key Laboratory of Neuropsychiatric Diseases and College of Pharmaceutical Sciences, Soochow University, Suzhou 215123, China
| | - Xiaoya Wan
- Department of Pharmacy, The Second Xiangya Hospital, Central South University, Changsha 410011, China
- Hunan Provincial Engineering Research Centre of Translational Medicine and Innovative Drug, Changsha 410011, China
| | - Wenjing Liu
- Department of Medicinal Chemistry, Jiangsu Key Laboratory of Neuropsychiatric Diseases and College of Pharmaceutical Sciences, Soochow University, Suzhou 215123, China
| | - Shilong Jiang
- Department of Pharmacy, Xiangya Hospital, Central South University, Changsha 410011, China
| | - Pan Deng
- Department of Medicinal Chemistry, Jiangsu Key Laboratory of Neuropsychiatric Diseases and College of Pharmaceutical Sciences, Soochow University, Suzhou 215123, China
| | - Yan Cheng
- Department of Pharmacy, The Second Xiangya Hospital, Central South University, Changsha 410011, China
- Hunan Provincial Engineering Research Centre of Translational Medicine and Innovative Drug, Changsha 410011, China
- Key Laboratory of Diabetes Immunology, Central South University, Ministry of Education, Changsha 410011, China
| | - Na Ye
- Department of Medicinal Chemistry, Jiangsu Key Laboratory of Neuropsychiatric Diseases and College of Pharmaceutical Sciences, Soochow University, Suzhou 215123, China
- Jiangsu Province Engineering Research Center of Precision Diagnostics and Therapeutics Development, Soochow University, Suzhou 215123, China
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Lkhagva-Yondon E, Seo MS, Oh Y, Jung J, Jeon E, Na K, Yoo HS, Kim WC, Esser C, Song SU, Jeon MS. The aryl hydrocarbon receptor controls mesenchymal stromal cell-mediated immunomodulation via ubiquitination of eukaryotic elongation factor-2 kinase. Cell Death Dis 2023; 14:812. [PMID: 38071243 PMCID: PMC10710493 DOI: 10.1038/s41419-023-06341-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Revised: 11/07/2023] [Accepted: 11/27/2023] [Indexed: 12/18/2023]
Abstract
Mesenchymal stem cells (MSCs) have great therapeutic advantages due to their immunosuppressive properties. The aryl hydrocarbon receptor (AHR) is a ligand-activated transcription factor whose signaling plays an important role in the immune system. AHR may be involved in the regulation of MSC-associated immunomodulatory functions. However, the mechanisms by which AHR controls the immunosuppressive functions of MSCs are not well understood. Here, we report that Ahr-deficient MSCs show decreased therapeutic efficacy against graft-versus-host disease (GVHD) compared to wild-type (WT)-MSCs. This was probably due to decreased iNOS protein expression, which is a key regulatory enzyme in MSC immunomodulation. The expression of eukaryotic elongation factor 2 kinase (eEF2K), which inhibits the elongation stage of protein synthesis, is significantly increased in the Ahr-deficient MSCs. Inhibition of eEF2K restored iNOS protein expression. AHR is known to act as an E3 ligase together with CUL4B. We observed constitutive binding of AHR to eEF2K. Consequently, ubiquitination and degradation of eEF2K were inhibited in Ahr-deficient MSCs and by the AHR antagonist CH223191 in WT-MSCs. In summary, AHR regulates the immunomodulatory functions of MSCs through ubiquitination of eEF2K, thereby controlling iNOS protein synthesis and its product, nitric oxide levels.
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Affiliation(s)
- Enkhmaa Lkhagva-Yondon
- Translational Research Center, Inha University Hospital, Incheon, 22332, Republic of Korea
- Program in Biomedical Science & Engineering Inha University, Incheon, 22212, Republic of Korea
| | - Myeong Seong Seo
- Translational Research Center, Inha University Hospital, Incheon, 22332, Republic of Korea
- Program in Biomedical Science & Engineering Inha University, Incheon, 22212, Republic of Korea
| | - Yena Oh
- Translational Research Center, Inha University Hospital, Incheon, 22332, Republic of Korea
- Department of Molecular Biomedicine, College of Medicine Inha University, Incheon, 22212, Republic of Korea
| | - Jonghun Jung
- Translational Research Center, Inha University Hospital, Incheon, 22332, Republic of Korea
- Program in Biomedical Science & Engineering Inha University, Incheon, 22212, Republic of Korea
| | - Eunhae Jeon
- Translational Research Center, Inha University Hospital, Incheon, 22332, Republic of Korea
- Department of Molecular Biomedicine, College of Medicine Inha University, Incheon, 22212, Republic of Korea
| | - Kwangmin Na
- Translational Research Center, Inha University Hospital, Incheon, 22332, Republic of Korea
| | - Hyun Seung Yoo
- Translational Research Center, Inha University Hospital, Incheon, 22332, Republic of Korea
- Department of Molecular Biomedicine, College of Medicine Inha University, Incheon, 22212, Republic of Korea
| | - Woo Chul Kim
- Department of Radiation Oncology, Inha University Hospital, Incheon, 22332, Republic of Korea
| | - Charlotte Esser
- IUF-Leibniz Research Institute for Environmental Medicine, Düsseldorf, 40021, Germany
| | - Sun U Song
- Translational Research Center, Inha University Hospital, Incheon, 22332, Republic of Korea
- Department of Molecular Biomedicine, College of Medicine Inha University, Incheon, 22212, Republic of Korea
- SCM Lifescience, Incheon, 21999, Republic of Korea
| | - Myung-Shin Jeon
- Translational Research Center, Inha University Hospital, Incheon, 22332, Republic of Korea.
- Program in Biomedical Science & Engineering Inha University, Incheon, 22212, Republic of Korea.
- Department of Molecular Biomedicine, College of Medicine Inha University, Incheon, 22212, Republic of Korea.
- SCM Lifescience, Incheon, 21999, Republic of Korea.
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Karamali N, Ebrahimnezhad S, Khaleghi Moghadam R, Daneshfar N, Rezaiemanesh A. HRD1 in human malignant neoplasms: Molecular mechanisms and novel therapeutic strategy for cancer. Life Sci 2022; 301:120620. [PMID: 35533759 DOI: 10.1016/j.lfs.2022.120620] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Revised: 05/01/2022] [Accepted: 05/04/2022] [Indexed: 10/18/2022]
Abstract
In tumor cells, the endoplasmic reticulum (ER) plays an essential role in maintaining cellular proteostasis by stimulating unfolded protein response (UPR) underlying stress conditions. ER-associated degradation (ERAD) is a critical pathway of the UPR to protect cells from ER stress-induced apoptosis and the elimination of unfolded or misfolded proteins by the ubiquitin-proteasome system (UPS). 3-Hydroxy-3-methylglutaryl reductase degradation (HRD1) as an E3 ubiquitin ligase plays an essential role in the ubiquitination and dislocation of misfolded protein in ERAD. In addition, HRD1 can target other normal folded proteins. In various types of cancer, the expression of HRD1 is dysregulated, and it targets different molecules to develop cancer hallmarks or suppress the progression of the disease. Recent investigations have defined the role of HRD1 in drug resistance in types of cancer. This review focuses on the molecular mechanisms of HRD1 and its roles in cancer pathogenesis and discusses the worthiness of targeting HRD1 as a novel therapeutic strategy in cancer.
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Affiliation(s)
- Negin Karamali
- Student Research Committee, School of Medicine, Kermanshah University of Medical Sciences, Kermanshah, Iran; Department of Immunology, School of Medicine, Kermanshah University of Medical Sciences, Kermanshah, Iran.
| | - Samaneh Ebrahimnezhad
- Student Research Committee, School of Medicine, Kermanshah University of Medical Sciences, Kermanshah, Iran; Department of Immunology, School of Medicine, Kermanshah University of Medical Sciences, Kermanshah, Iran.
| | - Reihaneh Khaleghi Moghadam
- Student Research Committee, School of Medicine, Kermanshah University of Medical Sciences, Kermanshah, Iran; Department of Immunology, School of Medicine, Kermanshah University of Medical Sciences, Kermanshah, Iran.
| | - Niloofar Daneshfar
- Student Research Committee, School of Medicine, Kermanshah University of Medical Sciences, Kermanshah, Iran; Department of Immunology, School of Medicine, Kermanshah University of Medical Sciences, Kermanshah, Iran.
| | - Alireza Rezaiemanesh
- Department of Immunology, School of Medicine, Kermanshah University of Medical Sciences, Kermanshah, Iran.
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Exostosin glycosyltransferase 1 reduces porcine reproductive and respiratory syndrome virus infection through proteasomal degradation of nsp3 and nsp5. J Biol Chem 2021; 298:101548. [PMID: 34971707 PMCID: PMC8888461 DOI: 10.1016/j.jbc.2021.101548] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Accepted: 12/22/2021] [Indexed: 11/23/2022] Open
Abstract
Porcine reproductive and respiratory syndrome virus (PRRSV) continues to be a serious threat to the swine industry worldwide. Exostosin glycosyltransferase 1 (EXT1), an enzyme involved in the biosynthesis of heparin sulfate, has also been reported to be a host factor essential for a wide variety of pathogens. However, the role of EXT1 in PRRSV infection remains uncharted. Here we identified that PRRSV infection caused an increase of EXT1 expression. EXT1 knockdown promoted virus infection, while its overexpression inhibited virus infection, suggesting an inhibitory function of EXT1 to PRRSV infection. We found that EXT1 had no effects on the attachment, internalization, or release of PRRSV, but did restrict viral RNA replication. EXT1 was determined to interact with viral non-structural protein 3 (nsp3) and nsp5 via its N-terminal cytoplasmic tail and to enhance K48-linked polyubiquitination of these two nsps to promote their degradation. Furthermore, the C-terminal glycosyltransferase activity domain of EXT1 was necessary for nsp3 and nsp5 degradation. We also found that EXT2, a EXT1 homologue, interacted with EXT1 and inhibited PRRSV infection. Similarly, EXT1 effectively restricted porcine epidemic diarrhea virus (PEDV) and porcine enteric alphacoronavirus (PEAV) infection in Vero cells. Taken together, this study reveals that EXT1 may serve as a broad-spectrum host restriction factor and suggests a molecular basis for the potential development of therapeutics against PRRSV infection.
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5
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Ballard DJ, Peng HY, Das JK, Kumar A, Wang L, Ren Y, Xiong X, Ren X, Yang JM, Song J. Insights Into the Pathologic Roles and Regulation of Eukaryotic Elongation Factor-2 Kinase. Front Mol Biosci 2021; 8:727863. [PMID: 34532346 PMCID: PMC8438118 DOI: 10.3389/fmolb.2021.727863] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2021] [Accepted: 08/16/2021] [Indexed: 12/14/2022] Open
Abstract
Eukaryotic Elongation Factor-2 Kinase (eEF2K) acts as a negative regulator of protein synthesis, translation, and cell growth. As a structurally unique member of the alpha-kinase family, eEF2K is essential to cell survival under stressful conditions, as it contributes to both cell viability and proliferation. Known as the modulator of the global rate of protein translation, eEF2K inhibits eEF2 (eukaryotic Elongation Factor 2) and decreases translation elongation when active. eEF2K is regulated by various mechanisms, including phosphorylation through residues and autophosphorylation. Specifically, this protein kinase is downregulated through the phosphorylation of multiple sites via mTOR signaling and upregulated via the AMPK pathway. eEF2K plays important roles in numerous biological systems, including neurology, cardiology, myology, and immunology. This review provides further insights into the current roles of eEF2K and its potential to be explored as a therapeutic target for drug development.
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Affiliation(s)
- Darby J. Ballard
- Department of Microbial Pathogenesis and Immunology, Texas A&M University Health Science Center, Bryan, TX, United States
| | - Hao-Yun Peng
- Department of Microbial Pathogenesis and Immunology, Texas A&M University Health Science Center, Bryan, TX, United States
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX, United States
| | - Jugal Kishore Das
- Department of Microbial Pathogenesis and Immunology, Texas A&M University Health Science Center, Bryan, TX, United States
| | - Anil Kumar
- Department of Microbial Pathogenesis and Immunology, Texas A&M University Health Science Center, Bryan, TX, United States
| | - Liqing Wang
- Department of Microbial Pathogenesis and Immunology, Texas A&M University Health Science Center, Bryan, TX, United States
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX, United States
| | - Yijie Ren
- Department of Microbial Pathogenesis and Immunology, Texas A&M University Health Science Center, Bryan, TX, United States
| | - Xiaofang Xiong
- Department of Microbial Pathogenesis and Immunology, Texas A&M University Health Science Center, Bryan, TX, United States
| | - Xingcong Ren
- Department of Toxicology and Cancer Biology, University of Kentucky College of Medicine, Lexington, KY, United States
| | - Jin-Ming Yang
- Department of Toxicology and Cancer Biology, University of Kentucky College of Medicine, Lexington, KY, United States
| | - Jianxun Song
- Department of Microbial Pathogenesis and Immunology, Texas A&M University Health Science Center, Bryan, TX, United States
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Jiang M, Qi L, Jin K, Li L, Wu Y, Song D, Gan J, Huang M, Li Y, Song C. eEF2K as a novel metastatic and prognostic biomarker in gastric cancer patients. Pathol Res Pract 2021; 225:153568. [PMID: 34352439 DOI: 10.1016/j.prp.2021.153568] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Revised: 07/25/2021] [Accepted: 07/26/2021] [Indexed: 01/09/2023]
Abstract
BACKGROUND Although eukaryotic elongation factor 2 kinase (eEF2K) has been reported to be a potential oncogenic factor in many human cancers, its usefulness as a clinical prognostic biomarker for gastric cancer has not been investigated. METHODS In this study, data about 540 patients with stomach adenocarcinoma (STAD) were analyzed from The Cancer Genome Atlas (TCGA) and the Gene Expression Omnibus (GEO) databases to determine the expression of eEF2K. Immunohistochemistry (IHC), western blots, and real-time polymerase chain reaction (RT-PCR) were also performed to determine the clinical significance of eEF2K expression in 96 postoperative patients with gastric cancer. Among the 96 patients, 36 had low expression of eEF2K and 60 had high expression. RESULTS Analysis of the TCGA and GEO datasets revealed that eEF2K expression was significantly higher in the STAD tissue samples than in the non-tumorous gastric tissues. IHC, western blots, and RT-PCR confirmed these findings. The high expression level of eEF2K was found to be related to the presence of lymph node metastasis (p = 0.002). Moreover, multivariate analysis showed that eEF2K was an independent indicator of prognosis for overall survival (OS) (hazard ratio [HR] = 1.72, 95% confidence interval [CI] = 1.06-2.79; p = 0.03) and disease-free survival (DFS) (HR = 1.66, 95% CI = 0.997-2.765; p = 0.052) in patients with surgically resected STAD. CONCLUSION Collectively, our findings suggest that eEF2K is a clinical indicator of metastatic and prognostic significance for STAD survival and could serve as a potential therapeutic target.
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Affiliation(s)
- Mingxia Jiang
- Department of Gastrointestinal Oncology, Harbin Medical University Cancer Hospital, 150 Haping St, Nangang District, Harbin, Heilongjiang 150081, PR China.
| | - Ling Qi
- Department of Gastrointestinal Oncology, Harbin Medical University Cancer Hospital, 150 Haping St, Nangang District, Harbin, Heilongjiang 150081, PR China.
| | - Kexin Jin
- Department of Gastrointestinal Oncology, Harbin Medical University Cancer Hospital, 150 Haping St, Nangang District, Harbin, Heilongjiang 150081, PR China.
| | - Lisha Li
- Department of Gastrointestinal Oncology, Harbin Medical University Cancer Hospital, 150 Haping St, Nangang District, Harbin, Heilongjiang 150081, PR China.
| | - Yiming Wu
- Department of Gastrointestinal Oncology, Harbin Medical University Cancer Hospital, 150 Haping St, Nangang District, Harbin, Heilongjiang 150081, PR China.
| | - Dongfeng Song
- Department of Gastrointestinal Oncology, Harbin Medical University Cancer Hospital, 150 Haping St, Nangang District, Harbin, Heilongjiang 150081, PR China.
| | - Junqing Gan
- Department of Gastrointestinal Oncology, Harbin Medical University Cancer Hospital, 150 Haping St, Nangang District, Harbin, Heilongjiang 150081, PR China.
| | - Mei Huang
- Department of Gastrointestinal Oncology, Harbin Medical University Cancer Hospital, 150 Haping St, Nangang District, Harbin, Heilongjiang 150081, PR China.
| | - Yanjing Li
- Department of Gastrointestinal Oncology, Harbin Medical University Cancer Hospital, 150 Haping St, Nangang District, Harbin, Heilongjiang 150081, PR China.
| | - Chengxin Song
- Department of Colorectal Surgery, Harbin Medical University Cancer Hospital, Harbin 150081, China.
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Ji F, Zhou M, Sun Z, Jiang Z, Zhu H, Xie Z, Ouyang X, Zhang L, Li L. Integrative proteomics reveals the role of E3 ubiquitin ligase SYVN1 in hepatocellular carcinoma metastasis. Cancer Commun (Lond) 2021; 41:1007-1023. [PMID: 34196494 PMCID: PMC8504139 DOI: 10.1002/cac2.12192] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Revised: 12/29/2020] [Accepted: 06/22/2021] [Indexed: 12/16/2022] Open
Abstract
Background Tumor metastasis is a major factor for poor prognosis of hepatocellular carcinoma (HCC), but the relationship between ubiquitination and metastasis need to be studied more systematically. We analyzed the ubiquitinome of HCC in this study to have a more comprehensive insight into human HCC metastasis. Methods The protein ubiquitination levels in 15 HCC specimens with vascular invasion and 15 without vascular invasion were detected by ubiquitinome. Proteins with significantly different ubiquitination levels between HCCs with and without vascular invasion were used to predict E3 ubiquitin ligases associated with tumor metastasis. The topological network of protein substrates and corresponding E3 ubiquitin ligases was constructed to identify the key E3 ubiquitin ligase. Besides, the growth, migration and invasion ability of LM3 and HUH7 hepatoma cell lines with and without SYVN1 expression interference were measured by cell proliferation assay, subcutaneous tumor assay, umphal vein endothelium tube formation assay, transwell migration and invasion assays. Finally, the interacting proteins of SYVN1 were screened and verified by protein interaction omics, immunofluorescence, and immunoprecipitation. Ubiquitin levels of related protein substrates in LM3 and HUH7 cells were compared in negative control, SYVN1 knockdown, and SYVN1 overexpression groups. Results In this study, our whole‐cell proteomic dataset and ubiquitinomic dataset contained approximately 5600 proteins and 12,000 ubiquitinated sites. We discovered increased ubiquitinated sites with shorter ubiquitin chains during the progression of HCC metastasis. In addition, proteomic and ubiquitinomic analyses revealed that high expression of E3 ubiquitin‐protein ligase SYVN1 is related with tumor metastasis. Furthermore, we found that SYVN1 interacted with heat shock protein 90 (HSP90) and impacted the ubiquitination of eukaryotic elongation factor 2 kinase (EEF2K). Conclusions The ubiquitination profiles of HCC with and without vascular invasion were significantly different. SYVN1 was the most important E3 ubiquitin‐protein ligase responsible for this phenomenon, and it was related with tumor metastasis and growth. Therefore, SYVN1 might be a potential therapeutic target for HCC.
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Affiliation(s)
- Feiyang Ji
- State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang, 310003, P. R. China.,Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Hangzhou, Zhejiang, 310003, P. R. China
| | - Menghao Zhou
- State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang, 310003, P. R. China.,Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Hangzhou, Zhejiang, 310003, P. R. China
| | - Zeyu Sun
- State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang, 310003, P. R. China.,Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Hangzhou, Zhejiang, 310003, P. R. China
| | - Zhengyi Jiang
- State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang, 310003, P. R. China.,Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Hangzhou, Zhejiang, 310003, P. R. China
| | - Huihui Zhu
- Department of Hepatobiliary and Pancreatic Surgery, The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang, 310003, P. R. China
| | - Zhongyang Xie
- State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang, 310003, P. R. China.,Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Hangzhou, Zhejiang, 310003, P. R. China
| | - Xiaoxi Ouyang
- State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang, 310003, P. R. China.,Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Hangzhou, Zhejiang, 310003, P. R. China
| | - Lingjian Zhang
- State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang, 310003, P. R. China.,Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Hangzhou, Zhejiang, 310003, P. R. China
| | - Lanjuan Li
- State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang, 310003, P. R. China.,Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Hangzhou, Zhejiang, 310003, P. R. China
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8
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Xian J, Zhang Q, Guo X, Liang X, Liu X, Feng Y. A prognostic signature based on three non-coding RNAs for prediction of the overall survival of glioma patients. FEBS Open Bio 2019; 9:682-692. [PMID: 30984542 PMCID: PMC6443874 DOI: 10.1002/2211-5463.12602] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2018] [Revised: 01/21/2019] [Accepted: 01/24/2019] [Indexed: 12/11/2022] Open
Abstract
Recent studies have identified certain non‐coding RNAs (ncRNAs) as biomarkers of disease progression. Glioma is the most common primary intracranial cancer, with high mortality. Here, we developed a prognostic signature for prediction of overall survival (OS) of glioma patients by analyzing ncRNA expression profiles. We downloaded gene expression profiles of glioma patients along with their clinical information from the Gene Expression Omnibus and extracted ncRNA expression profiles via a microarray annotation file. Correlations between ncRNAs and glioma patients’ OS were first evaluated through univariate Cox regression analysis and a permutation test, followed by random survival forest analysis for further screening of valuable ncRNA signatures. Prognostic signatures could be established as a risk score formula by including ncRNA signature expression values weighted by their estimated regression coefficients. Patients could be divided into high risk and low risk subgroups by using the median risk score as cutoff. As a result, glioma patients with a high risk score tended to have shorter OS than those with low risk scores, which was confirmed by analyzing another set of glioma patients in an independent dataset. Additionally, gene set enrichment analysis showed significant enrichment of cancer development‐related biological processes and pathways. Our study may provide further insights into the evaluation of glioma patients’ prognosis.
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Affiliation(s)
- Junmin Xian
- Department of Neurosurgery The Affiliated Hospital of Qingdao University China.,Department of Neurosurgery Heze Municipal Hospital China
| | | | - Xiwen Guo
- Department of Neurosurgery Heze Municipal Hospital China
| | - Xiankun Liang
- Department of Neurosurgery Heze Municipal Hospital China
| | - Xinhua Liu
- School of Biomedical Engineering Tianjin Medical University China
| | - Yugong Feng
- Department of Neurosurgery The Affiliated Hospital of Qingdao University China
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9
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The Superimposed Deubiquitination Effect of OTULIN and Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) Nsp11 Promotes Multiplication of PRRSV. J Virol 2018; 92:JVI.00175-18. [PMID: 29444948 DOI: 10.1128/jvi.00175-18] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Accepted: 02/12/2018] [Indexed: 02/06/2023] Open
Abstract
Linear ubiquitination plays an important role in the regulation of the immune response by regulating nuclear factor κB (NF-κB). The linear ubiquitination-specific deubiquitinase ovarian tumor domain deubiquitinase with linear linkage specificity (OTULIN) can control the immune signaling transduction pathway by restricting the Met1-linked ubiquitination process. In our study, the porcine OTLLIN gene was cloned and deubiquitin functions were detected in a porcine reproductive and respiratory syndrome virus (PRRSV)-infected-cell model. PRRSV infection promotes the expression of the OTULIN gene; in turn, overexpression of OTULIN contributes to PRRSV proliferation. There is negative regulation of innate immunity with OTULIN during viral infection. The cooperative effects of swine OTULIN and PRRSV Nsp11 potentiate the ability to reduce levels of cellular protein ubiquitin associated with innate immunity. Importantly, PRRSV Nsp11 recruits OTULIN through a nonenzymatic combination to enhance its ability to remove linear ubiquitination targeting NEMO, resulting in a superimposed effect that inhibits the production of type I interferons (IFNs). Our report presents a new model of virus utilization of the ubiquitin-protease system in vivo from the perspective of the viral proteins that interact with cell deubiquitination enzymes, providing new ideas for prevention and control of PRRSV.IMPORTANCE Deubiquitination effects of swine OTULIN were identified. The interaction between porcine OTULIN and PRRSV Nsp11 is dependent on the OTU domain. PRRSV Nsp11 recruits OTULIN through a nonenzymatic combination to promote removal of linear ubiquitination targeting NEMO, resulting in a superimposed effect that inhibits the production of type I IFNs.
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Johanns M, Pyr Dit Ruys S, Houddane A, Vertommen D, Herinckx G, Hue L, Proud CG, Rider MH. Direct and indirect activation of eukaryotic elongation factor 2 kinase by AMP-activated protein kinase. Cell Signal 2017; 36:212-221. [PMID: 28502587 DOI: 10.1016/j.cellsig.2017.05.010] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Revised: 04/27/2017] [Accepted: 05/10/2017] [Indexed: 12/12/2022]
Abstract
BACKGROUND Eukaryotic elongation factor 2 (eEF2) kinase (eEF2K) is a key regulator of protein synthesis in mammalian cells. It phosphorylates and inhibits eEF2, the translation factor necessary for peptide translocation during the elongation phase of protein synthesis. When cellular energy demand outweighs energy supply, AMP-activated protein kinase (AMPK) and eEF2K become activated, leading to eEF2 phosphorylation, which reduces the rate of protein synthesis, a process that consumes a large proportion of cellular energy under optimal conditions. AIM The goal of the present study was to elucidate the mechanisms by which AMPK activation leads to increased eEF2 phosphorylation to decrease protein synthesis. METHODS Using genetically modified mouse embryo fibroblasts (MEFs), effects of treatments with commonly used AMPK activators to increase eEF2 phosphorylation were compared with that of the novel compound 991. Bacterially expressed recombinant eEF2K was phosphorylated in vitro by recombinant activated AMPK for phosphorylation site-identification by mass spectrometry followed by site-directed mutagenesis of the identified sites to alanine residues to study effects on the kinetic properties of eEF2K. Wild-type eEF2K and a Ser491/Ser492 mutant were retrovirally re-introduced in eEF2K-deficient MEFs and effects of 991 treatment on eEF2 phosphorylation and protein synthesis rates were studied in these cells. RESULTS & CONCLUSIONS AMPK activation leads to increased eEF2 phosphorylation in MEFs mainly by direct activation of eEF2K and partly by inhibition of mammalian target of rapamycin complex 1 (mTORC1) signaling. Treatment of MEFs with AMPK activators can also lead to eEF2K activation independently of AMPK probably via a rise in intracellular Ca2+. AMPK activates eEF2K by multi-site phosphorylation and the newly identified Ser491/Ser492 is important for activation, leading to mTOR-independent inhibition of protein synthesis. Our study provides new insights into the control of eEF2K by AMPK, with implications for linking metabolic stress to decreased protein synthesis to conserve energy reserves, a pathway that is of major importance in cancer cell survival.
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Affiliation(s)
- M Johanns
- Université catholique de Louvain (UCL), de Duve Institute, Avenue Hippocrate 75 bte 74.02, 1200-Brussels, Belgium
| | - S Pyr Dit Ruys
- Université catholique de Louvain (UCL), de Duve Institute, Avenue Hippocrate 75 bte 74.02, 1200-Brussels, Belgium
| | - A Houddane
- Université catholique de Louvain (UCL), de Duve Institute, Avenue Hippocrate 75 bte 74.02, 1200-Brussels, Belgium
| | - D Vertommen
- Université catholique de Louvain (UCL), de Duve Institute, Avenue Hippocrate 75 bte 74.02, 1200-Brussels, Belgium
| | - G Herinckx
- Université catholique de Louvain (UCL), de Duve Institute, Avenue Hippocrate 75 bte 74.02, 1200-Brussels, Belgium
| | - L Hue
- Université catholique de Louvain (UCL), de Duve Institute, Avenue Hippocrate 75 bte 74.02, 1200-Brussels, Belgium
| | - C G Proud
- South Australian Health and Medical Research Institute (SAHMRI), University of Adelaide, North Terrace, Adelaide, SA 5000, Australia
| | - M H Rider
- Université catholique de Louvain (UCL), de Duve Institute, Avenue Hippocrate 75 bte 74.02, 1200-Brussels, Belgium.
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11
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Regulated stability of eukaryotic elongation factor 2 kinase requires intrinsic but not ongoing activity. Biochem J 2015; 467:321-31. [DOI: 10.1042/bj20150089] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Eukaryotic elongation factor 2 kinase (eEF2K) is an atypical protein kinase which negatively regulates protein synthesis, is activated under stress conditions and plays a role in cytoprotection, e.g. in cancer cells. It is regarded as a possible target for therapeutic intervention in solid tumours. Earlier studies showed that eEF2K is degraded by a proteasome-dependent pathway in response to genotoxic stress and that this requires a phosphodegron that includes an autophosphorylation site. Thus, application of eEF2K inhibitors would stabilize eEF2K, partially negating the effects of inhibiting its activity. In the present study, we show that under a range of other stress conditions, including acidosis or treatment of cells with 2-deoxyglucose, eEF2K is also degraded. However, in these settings, the previously identified phosphodegron is not required for its degradation. Nevertheless, kinase-dead and other activity-deficient mutants of eEF2K are stabilized, as is a mutant lacking a critical autophosphorylation site (Thr348 in eEF2K), which is thought to be required for eEF2K and other α-kinases to achieve their active conformations. In contrast, application of small-molecule eEF2K inhibitors does not stabilize the protein. Our data suggest that achieving an active conformation, rather than eEF2K activity per se, is required for its susceptibility to degradation. Additional degrons and E3 ligases beyond those already identified are probably involved in regulating eEF2K levels. Our findings have significant implications for therapeutic targeting of eEF2K, e.g. in oncology.
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Elongation Factor 2 Kinase Is Regulated by Proline Hydroxylation and Protects Cells during Hypoxia. Mol Cell Biol 2015; 35:1788-804. [PMID: 25755286 DOI: 10.1128/mcb.01457-14] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2014] [Accepted: 03/01/2015] [Indexed: 12/19/2022] Open
Abstract
Protein synthesis, especially translation elongation, requires large amounts of energy, which is often generated by oxidative metabolism. Elongation is controlled by phosphorylation of eukaryotic elongation factor 2 (eEF2), which inhibits its activity and is catalyzed by eEF2 kinase (eEF2K), a calcium/calmodulin-dependent α-kinase. Hypoxia causes the activation of eEF2K and induces eEF2 phosphorylation independently of previously known inputs into eEF2K. Here, we show that eEF2K is subject to hydroxylation on proline-98. Proline hydroxylation is catalyzed by proline hydroxylases, oxygen-dependent enzymes which are inactivated during hypoxia. Pharmacological inhibition of proline hydroxylases also stimulates eEF2 phosphorylation. Pro98 lies in a universally conserved linker between the calmodulin-binding and catalytic domains of eEF2K. Its hydroxylation partially impairs the binding of calmodulin to eEF2K and markedly limits the calmodulin-stimulated activity of eEF2K. Neuronal cells depend on oxygen, and eEF2K helps to protect them from hypoxia. eEF2K is the first example of a protein directly involved in a major energy-consuming process to be regulated by proline hydroxylation. Since eEF2K is cytoprotective during hypoxia and other conditions of nutrient insufficiency, it may be a valuable target for therapy of poorly vascularized solid tumors.
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Qin Y, Lin L, Chen Y, Wu S, Si X, Wu H, Zhai X, Wang Y, Tong L, Pan B, Zhong X, Wang T, Zhao W, Zhong Z. Curcumin inhibits the replication of enterovirus 71 in vitro. Acta Pharm Sin B 2014; 4:284-94. [PMID: 26579397 PMCID: PMC4629085 DOI: 10.1016/j.apsb.2014.06.006] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2014] [Revised: 06/06/2014] [Accepted: 06/20/2014] [Indexed: 11/16/2022] Open
Abstract
Human enterovirus 71 (EV71) is the main causative pathogen of hand, foot, and mouth disease (HFMD) in children. The epidemic of HFMD has been a public health problem in Asia-Pacific region for decades, and no vaccine and effective antiviral medicine are available. Curcumin has been used as a traditional medicine for centuries to treat a diversity of disorders including viral infections. In this study, we demonstrated that curcumin showed potent antiviral effect again EV71. In Vero cells infected with EV71, the addition of curcumin significantly suppressed the synthesis of viral RNA, the expression of viral protein, and the overall production of viral progeny. Similar with the previous reports, curcumin reduced the production of ROS induced by viral infection. However, the antioxidant property of curcumin did not contribute to its antiviral activity, since N-acetyl-l-cysteine, the potent antioxidant failed to suppress viral replication. This study also showed that extracellular signal-regulated kinase (ERK) was activated by either viral infection or curcumin treatment, but the activated ERK did not interfere with the antiviral effect of curcumin, indicating ERK is not involved in the antiviral mechanism of curcumin. Unlike the previous reports that curcumin inhibited protein degradation through ubiquitin–proteasome system (UPS), we found that curcumin had no impact on UPS in control cells. However, curcumin did reduce the activity of proteasomes which was increased by viral infection. In addition, the accumulation of the short-lived proteins, p53 and p21, was increased by the treatment of curcumin in EV71-infected cells. We further probed the antiviral mechanism of curcumin by examining the expression of GBF1 and PI4KB, both of which are required for the formation of viral replication complex. We found that curcumin significantly reduced the level of both proteins. Moreover, the decreased expression of either GBF1 or PI4KB by the application of siRNAs was sufficient to suppress viral replication. We also demonstrated that curcumin showed anti-apoptotic activity at the early stage of viral infection. The results of this study provide solid evidence that curcumin has potent anti-EV71 activity. Whether or not the down-regulated GBF1 and PI4KB by curcumin contribute to its antiviral effect needs further studies.
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Key Words
- Apoptosis
- CVB, coxsackieviurs B
- Curcumin
- DCFH-DA, dichloro-dihydro-fluorescein diacetate
- ERK, extracellular signal-regulated kinase
- EV71, enterovirus 71
- Enterovirus 71
- GBF1
- GBF1, Golgi brefeldin A resistant guanine nucleotide exchange factor 1
- GEF, guanine nucleotide exchange factor
- HBV, hepatitis B virus
- HCV, hepatitis C virus
- HFMD, hand, foot, and mouth disease
- HIV, human immunodeficiency virus
- HPV, human papillomavirus
- NAC, N-acetyl-l-cysteine
- PARP-1, poly(ADP-ribose) polymerase
- PGC-1α, peroxisome proliferator-activated receptor-gamma co-activator 1 alpha
- PI4KB
- PI4KB, phosphatidylinositol 4-kinase class III catalytic subunit β
- PI4P, phosphatidylinositol 4-phosphate
- ROS, reactive oxygen species
- SLLVY-AMC, succinyl-Leu-Leu-Val-Tyr-7-amino-4-methylcoumarin
- UPS, ubiquitin–proteasome system
- Ubiquitin–proteasome system
- Viral replication
- p.i., post-infection
- siRNA, small interfering RNA
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Celastrol targets proteostasis and acts synergistically with a heat-shock protein 90 inhibitor to kill human glioblastoma cells. Cell Death Dis 2014; 5:e1216. [PMID: 24810052 PMCID: PMC4047902 DOI: 10.1038/cddis.2014.182] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2013] [Revised: 03/06/2014] [Accepted: 03/24/2014] [Indexed: 12/31/2022]
Abstract
Glioblastoma multiforme is a devastating disease of the central nervous system and, at present, no effective therapeutic interventions have been identified. Celastrol, a natural occurring triterpene, exhibits potent anti-tumor activity against gliomas in xenograft mouse models. In this study, we describe the cell death mechanism employed by celastrol and identify secondary targets for effective combination therapy against glioblastoma cell survival. In contrast to the previously proposed reactive oxygen species (ROS)-dependent mechanism, cell death in human glioblastoma cells is shown here to be mediated by alternate signal transduction pathways involving, but not fully dependent on, poly(ADP-ribose) polymerase-1 and caspase-3. Our studies indicate that celastrol promotes proteotoxic stress, supported by two feedback mechanisms: (i) impairment of protein quality control as revealed by accumulation of polyubiquitinated aggregates and the canonical autophagy substrate, p62, and (ii) the induction of heat-shock proteins, HSP72 and HSP90. The Michael adduct of celastrol and N-acetylcysteine, 6-N-acetylcysteinyldihydrocelastrol, had no effect on p62, nor on HSP72 expression, confirming a thiol-dependent mechanism. Restriction of protein folding stress with cycloheximide was protective, while combination with autophagy inhibitors did not sensitize cells to celastrol-mediated cytotoxicity. Collectively, these findings imply that celastrol targets proteostasis by disrupting sulfyhydryl homeostasis, independently of ROS, in human glioblastoma cells. This study further emphasizes that targeting proteotoxic stress responses by inhibiting HSP90 with 17-N-Allylamino-17-demethoxygeldanamycin sensitizes human glioblastoma to celastrol treatment, thereby serving as a novel synergism to overcome drug resistance.
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Kenney JW, Moore CE, Wang X, Proud CG. Eukaryotic elongation factor 2 kinase, an unusual enzyme with multiple roles. Adv Biol Regul 2014; 55:15-27. [PMID: 24853390 DOI: 10.1016/j.jbior.2014.04.003] [Citation(s) in RCA: 132] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Accepted: 04/15/2014] [Indexed: 12/27/2022]
Abstract
Eukaryotic elongation factor 2 kinase (eEF2K) is a member of the small group of atypical 'α-kinases'. It phosphorylates and inhibits eukaryotic elongation factor 2, to slow down the elongation stage of protein synthesis, which normally consumes a great deal of energy and amino acids. The activity of eEF2K is normally dependent on calcium ions and calmodulin. eEF2K is also regulated by a plethora of other inputs, including inhibition by signalling downstream of anabolic signalling pathways such as the mammalian target of rapamycin complex 1. Recent data show that eEF2K helps to protect cancer cells against nutrient starvation and is also cytoprotective in other settings, including hypoxia. Growing evidence points to roles for eEF2K in neurological processes such as learning and memory and perhaps in depression.
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Affiliation(s)
- Justin W Kenney
- Centre for Biological Sciences, Life Sciences Building, University of Southampton, Southampton, SO16 7LB, UK
| | - Claire E Moore
- Centre for Biological Sciences, Life Sciences Building, University of Southampton, Southampton, SO16 7LB, UK
| | - Xuemin Wang
- Centre for Biological Sciences, Life Sciences Building, University of Southampton, Southampton, SO16 7LB, UK
| | - Christopher G Proud
- Centre for Biological Sciences, Life Sciences Building, University of Southampton, Southampton, SO16 7LB, UK.
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16
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Akcakanat A, Hong DS, Meric-Bernstam F. Targeting translation initiation in breast cancer. ACTA ACUST UNITED AC 2014; 2:e28968. [PMID: 26779407 PMCID: PMC4705830 DOI: 10.4161/trla.28968] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2014] [Revised: 04/09/2014] [Accepted: 04/22/2014] [Indexed: 12/23/2022]
Abstract
Over the past 20 years, a better understanding of cancer biology, screening for early detection, improved adjuvant treatment, and targeted therapies have decreased the rate of breast cancer deaths. However, resistance to treatment is common, and new approaches are needed. Deregulation of translation initiation is associated with the commencement and progression of cancer. Often, translation initiation factors are overexpressed and the related signaling pathways activated in human tumors. Recently, a significant number of inhibitors that target translation factors and pathways have become available. These inhibitors are being tested alone or in combination with chemotherapeutic agents in clinical trials. The results are varied, and it is not yet clear which drug treatments most effectively inhibit tumor growth. This review highlights the pathways and downstream effects of the activation of translation and discusses targeting the control of translation initiation as a therapeutic approach in cancer, focusing on breast cancer clinical trials.
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Affiliation(s)
- Argun Akcakanat
- Department of Investigational Cancer Therapeutics; Houston, TX USA
| | - David S Hong
- Department of Investigational Cancer Therapeutics; Houston, TX USA
| | - Funda Meric-Bernstam
- Department of Investigational Cancer Therapeutics; Houston, TX USA; Department of Surgical Oncology; The University of Texas MD Anderson Cancer Center; Houston, TX USA
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17
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Liu R, Iadevaia V, Averous J, Taylor PM, Zhang Z, Proud CG. Impairing the production of ribosomal RNA activates mammalian target of rapamycin complex 1 signalling and downstream translation factors. Nucleic Acids Res 2014; 42:5083-96. [PMID: 24526220 PMCID: PMC4005692 DOI: 10.1093/nar/gku130] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Ribosome biogenesis is a key process for maintaining protein synthetic capacity in dividing or growing cells, and requires coordinated production of ribosomal proteins and ribosomal RNA (rRNA), including the processing of the latter. Signalling through mammalian target of rapamycin complex 1 (mTORC1) activates all these processes. Here, we show that, in human cells, impaired rRNA processing, caused by expressing an interfering mutant of BOP1 or by knocking down components of the PeBoW complex elicits activation of mTORC1 signalling. This leads to enhanced phosphorylation of its substrates S6K1 and 4E-BP1, and stimulation of proteins involved in translation initiation and elongation. In particular, we observe both inactivation and downregulation of the eukaryotic elongation factor 2 kinase, which normally inhibits translation elongation. The latter effect involves decreased expression of the eEF2K mRNA. The mRNAs for ribosomal proteins, whose translation is positively regulated by mTORC1 signalling, also remain associated with ribosomes. Therefore, our data demonstrate that disrupting rRNA production activates mTORC1 signalling to enhance the efficiency of the translational machinery, likely to help compensate for impaired ribosome production.
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Affiliation(s)
- Rui Liu
- Centre for Biological Sciences, University of Southampton, Highfield Campus, Southampton SO17 1BJ, UK, Centre de Recherche en Nutrition Humaine, INRA Clermont-Theix, Unité de Nutrition Humaine, 63122 Ceyrat, France and Division of Molecular Physiology, James Black Centre, College of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK
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18
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Ashour AA, Abdel-Aziz AAH, Mansour AM, Alpay SN, Huo L, Ozpolat B. Targeting elongation factor-2 kinase (eEF-2K) induces apoptosis in human pancreatic cancer cells. Apoptosis 2014; 19:241-58. [PMID: 24193916 DOI: 10.1007/s10495-013-0927-2] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Pancreatic cancer (PaCa) is one of the most aggressive, apoptosis-resistant and currently incurable cancers with a poor survival rate. Eukaryotic elongation factor-2 kinase (eEF-2K) is an atypical kinase, whose role in PaCa survival is not yet known. Here, we show that eEF-2K is overexpressed in PaCa cells and its down-regulation induces apoptotic cell death. Rottlerin (ROT), a polyphenolic compound initially identified as a PKC-δ inhibitor, induces apoptosis and autophagy in a variety of cancer cells including PaCa cells. We demonstrated that ROT induces intrinsic apoptosis, with dissipation of mitochondrial membrane potential (ΔΨm), and stimulates extrinsic apoptosis with concomitant induction of TNF-related apoptosis inducing ligand (TRAIL) receptors, DR4 and DR5, with caspase-8 activation, in PANC-1 and MIAPaCa-2 cells. Notably, while none of these effects were dependent on PKC-δ inhibition, ROT down-regulates eEF-2K at mRNA level, and induce eEF-2K protein degradation through ubiquitin-proteasome pathway. Down-regulation of eEF-2K recapitulates the events observed after ROT treatment, while its over-expression suppressed the ROT-induced apoptosis. Furthermore, eEF-2K regulates the expression of tissue transglutaminase (TG2), an enzyme previously implicated in proliferation, drug resistance and survival of cancer cells. Inhibition of eEF-2K/TG2 axis leads to caspase-independent apoptosis which is associated with induction of apoptosis-inducing factor (AIF). Collectively, these results indicate, for the first time, that the down-regulation of eEF-2K leads to induction of intrinsic, extrinsic as well as AIF-dependent apoptosis in PaCa cells, suggesting that eEF-2K may represent an attractive therapeutic target for the future anticancer agents in PaCa.
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Affiliation(s)
- Ahmed A Ashour
- Department of Experimental Therapeutics, Unit 422, The University of Texas, M.D. Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX, 77030, USA
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McBride EG, Rubel EW, Wang Y. Afferent regulation of chicken auditory brainstem neurons: rapid changes in phosphorylation of elongation factor 2. J Comp Neurol 2013; 521:1165-83. [PMID: 22987813 DOI: 10.1002/cne.23227] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2012] [Revised: 08/27/2012] [Accepted: 09/07/2012] [Indexed: 12/21/2022]
Abstract
The relationships between protein synthesis and neuronal survival are poorly understood. In chicken nucleus magnocellularis (NM), significant alterations in overall protein synthesis precede neuronal death induced by deprivation of excitatory afferent activity. Previously we demonstrated an initial reduction in the overall rate of protein synthesis in all deprived NM neurons, followed by quick recovery (starting at 6 hours) in some, but not all, neurons. Neurons with recovered protein synthesis ultimately survive, whereas others become "ghost" cells (no detectable Nissl substance) at 12-24 hours and die within 48 hours. To explore the mechanisms underlying this differential influence of afferent input on protein synthesis and cell survival, the current study investigates the involvement of eukaryotic translation elongation factor 2 (eEF2), the phosphorylation of which reduces overall protein synthesis. Using immunocytochemistry for either total or phosphorylated eEF2 (p-eEF2), we found significant reductions in the level of phosphorylated, but not total, eEF2 in NM neurons as early as 0.5-1 hour following cochlea removal. Unexpectedly, neurons with low levels of p-eEF2 show reduced protein synthesis at 6 hours, indicated by a marker for active ribosomes. At 12 hours, all "ghost" cells exhibited little or no p-eEF2 staining, although not every neuron with a comparable low level of p-eEF2 was a "ghost" cell. These observations demonstrate that a reduced level of p-eEF2 is not responsible for immediate responses (including reduced overall protein synthesis) of a neuron to compromised afferent input but may impair the neuron's ability to initiate recovery signaling for survival and make the neuron more vulnerable to death.
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Affiliation(s)
- Ethan G McBride
- Virginia Merrill Bloedel Hearing Research Center, Department of Otolaryngology-Head and Neck Surgery, University of Washington School of Medicine, Seattle, Washington 98195, USA
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The role of eukaryotic elongation factor 2 kinase in rapid antidepressant action of ketamine. Biol Psychiatry 2013; 73:1199-203. [PMID: 23062356 PMCID: PMC3574622 DOI: 10.1016/j.biopsych.2012.09.006] [Citation(s) in RCA: 143] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2012] [Revised: 08/30/2012] [Accepted: 09/05/2012] [Indexed: 01/26/2023]
Abstract
Major depressive disorder is a devastating mental disorder. Current antidepressant medications can be effective for some patients with depression; however, these drugs exert mood-elevating effects only after prolonged administration, and a sizable fraction of the patient population fails to respond to treatment. There is an urgent need for faster-acting antidepressants with reliable treatment outcomes and sustained efficacy for individuals with depression, in particular those contemplating suicide. Recent clinical studies report that ketamine, an ionotropic glutamatergic N-methyl-D-aspartate (NMDA) receptor blocker, shows fast-acting antidepressant action, thus bringing fresh perspective into preclinical studies investigating novel antidepressant targets and treatments. Our recent studies show that the effects of ketamine are dependent on brain-derived neurotrophic factor (BDNF) and subsequent activation of the high-affinity BDNF receptor, TrkB. Our findings also suggest that the fast-acting antidepressant effects of ketamine require rapid protein translation, but not transcription, resulting in robust increases in dendritic BDNF protein levels that are important for the behavioral effect. These findings also uncover eukaryotic elongation factor 2 kinase (eEF2K), a Ca²⁺/calmodulin dependent serine/threonine kinase that phosphorylates eEF2 and regulates the elongation step of protein translation, as a major molecular substrate mediating the rapid antidepressant effect of ketamine. Our results show that ketamine-mediated suppression of resting NMDA receptor activity leads to inhibition of eEF2 kinase and subsequent dephosphorylation of eEF2 and augmentation of BDNF synthesis. This article outlines our recent studies on the synaptic mechanisms that underlie ketamine action, in particular the properties of eEF2K as a potential antidepressant target.
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Vlachostergios PJ, Voutsadakis IA, Papandreou CN. The role of ubiquitin-proteasome system in glioma survival and growth. Growth Factors 2013; 31:106-13. [PMID: 23688106 DOI: 10.3109/08977194.2013.799156] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
High-grade gliomas represent a group of aggressive brain tumors with poor prognosis due to an inherent capacity of persistent cell growth and survival. The ubiquitin-proteasome system (UPS) is an intracellular machinery responsible for protein turnover. Emerging evidence implicates various proteins targeted for degradation by the UPS in key survival and proliferation signaling pathways of these tumors. In this review, we discuss the involvement of UPS in the regulation of several mediators and effectors of these pathways in malignant gliomas.
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Affiliation(s)
- Panagiotis J Vlachostergios
- Department of Medical Oncology, Faculty of Medicine, School of Health Sciences, University of Thessaly, University Hospital of Larissa, Larissa, Greece.
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Wiseman SL, Shimizu Y, Palfrey C, Nairn AC. Proteasomal degradation of eukaryotic elongation factor-2 kinase (EF2K) is regulated by cAMP-PKA signaling and the SCFβTRCP ubiquitin E3 ligase. J Biol Chem 2013; 288:17803-11. [PMID: 23640883 DOI: 10.1074/jbc.m113.477182] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Protein translation and degradation are critical for proper protein homeostasis, yet it remains unclear how these processes are dynamically regulated, or how they may directly balance or synergize with each other. An important translational control mechanism is the Ca(2+)/calmodulin-dependent phosphorylation of eukaryotic elongation factor-2 (eEF-2) by eukaryotic elongation factor-2 kinase (EF2K), which inhibits elongation of nascent polypeptide chains during translation. We previously described a reduction of EF2K activity in PC12 cells treated with NGF or forskolin. Here, we show that both forskolin- and IGF-1-mediated reductions of EF2K activity in PC12 cells are due to decreased EF2K protein levels, and this is attenuated by application of the proteasome inhibitor, MG132. We further demonstrate that proteasome-mediated degradation of EF2K occurs in response to A2A-type adenosine receptor stimulation, and that activation of protein kinase A (PKA) or phospho-mimetic mutation of the previously characterized PKA site, Ser-499, were sufficient to induce EF2K turnover in PC12 cells. A similar EF2K degradation mechanism was observed in primary neurons and HEK cells. Expression of a dominant-negative form of Cul1 in HEK cells demonstrated that EF2K levels are regulated by an SCF-type ubiquitin E3 ligase. Specifically, EF2K binds to the F-box proteins, βTRCP1 and βTRCP2, and βTRCP regulates EF2K levels and polyubiquitylation. We propose that the proteasomal degradation of EF2K provides a mechanistic link between activity-dependent protein synthesis and degradation.
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Affiliation(s)
- Shari L Wiseman
- Department of Psychiatry, Yale University School of Medicine, New Haven, Connecticut 06508, USA
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Tekedereli I, Alpay SN, Tavares CDJ, Cobanoglu ZE, Kaoud TS, Sahin I, Sood AK, Lopez-Berestein G, Dalby KN, Ozpolat B. Targeted silencing of elongation factor 2 kinase suppresses growth and sensitizes tumors to doxorubicin in an orthotopic model of breast cancer. PLoS One 2012; 7:e41171. [PMID: 22911754 PMCID: PMC3401164 DOI: 10.1371/journal.pone.0041171] [Citation(s) in RCA: 90] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2012] [Accepted: 06/18/2012] [Indexed: 11/18/2022] Open
Abstract
Eukaryotic elongation factor 2 kinase (eEF-2K), through its phosphorylation of elongation factor 2 (eEF2), provides a mechanism by which cells can control the rate of the elongation phase of protein synthesis. The activity of eEF-2K is increased in rapidly proliferating malignant cells, is inhibited during mitosis, and may contribute to the promotion of autophagy in response to anti-cancer therapies. The purpose of this study was to examine the therapeutic potential of targeting eEF-2K in breast cancer tumors. Through the systemic administration of liposomal eEF-2K siRNA (twice a week, i.v. 150 µg/kg), the expression of eEF-2K was down-regulated in vivo in an orthotopic xenograft mouse model of a highly aggressive triple negative MDA-MB-231 tumor. This targeting resulted in a substantial decrease in eEF2 phosphorylation in the tumors, and led to the inhibition of tumor growth, the induction of apoptosis and the sensitization of tumors to the chemotherapy agent doxorubicin. eEF-2K down-modulation in vitro resulted in a decrease in the expression of c-Myc and cyclin D1 with a concomitant increase in the expression of p27Kip1. A decrease in the basal activity of c-Src (phospho-Tyr-416), focal adhesion kinase (phospho-Tyr-397), and Akt (phospho-Ser-473) was also detected following eEF-2K down-regulation in MDA-MB-231 cells, as determined by Western blotting. Where tested, similar results were seen in ER-positive MCF-7 cells. These effects were also accompanied by a decrease in the observed invasive phenotype of the MDA-MB-231 cells. These data support the notion that the disruption of eEF-2K expression in breast cancer cells results in the down-regulation of signaling pathways affecting growth, survival and resistance and has potential as a therapeutic approach for the treatment of breast cancer.
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Affiliation(s)
- Ibrahim Tekedereli
- Department of Experimental Therapeutics, University of Texas M. D. Anderson Cancer Center, Houston, Texas, United States of America
| | - S. Neslihan Alpay
- Department of Experimental Therapeutics, University of Texas M. D. Anderson Cancer Center, Houston, Texas, United States of America
| | - Clint D. J. Tavares
- Graduate Program in Cell and Molecular Biology, The University of Texas, Austin, Texas, United States of America
| | - Zehra E. Cobanoglu
- Department of Experimental Therapeutics, University of Texas M. D. Anderson Cancer Center, Houston, Texas, United States of America
| | - Tamer S. Kaoud
- Division of Medicinal Chemistry, College of Pharmacy, The University of Texas, Austin, Texas, United States of America
| | - Ibrahim Sahin
- Department of Experimental Therapeutics, University of Texas M. D. Anderson Cancer Center, Houston, Texas, United States of America
| | - Anil K. Sood
- Department of Gynecologic Oncology, University of Texas M. D. Anderson Cancer Center, Houston, Texas, United States of America
- Department of Cancer Biology, University of Texas M. D. Anderson Cancer Center, Houston, Texas, United States of America
- Center for RNAi and Non-Coding RNA, University of Texas M. D. Anderson Cancer Center, Houston, Texas, United States of America
| | - Gabriel Lopez-Berestein
- Department of Experimental Therapeutics, University of Texas M. D. Anderson Cancer Center, Houston, Texas, United States of America
- Department of Cancer Biology, University of Texas M. D. Anderson Cancer Center, Houston, Texas, United States of America
- Center for RNAi and Non-Coding RNA, University of Texas M. D. Anderson Cancer Center, Houston, Texas, United States of America
| | - Kevin N. Dalby
- Graduate Program in Cell and Molecular Biology, The University of Texas, Austin, Texas, United States of America
- Division of Medicinal Chemistry, College of Pharmacy, The University of Texas, Austin, Texas, United States of America
- * E-mail: (BO); (KND)
| | - Bulent Ozpolat
- Department of Experimental Therapeutics, University of Texas M. D. Anderson Cancer Center, Houston, Texas, United States of America
- Center for RNAi and Non-Coding RNA, University of Texas M. D. Anderson Cancer Center, Houston, Texas, United States of America
- * E-mail: (BO); (KND)
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Huber-Keener KJ, Evans BR, Ren X, Cheng Y, Zhang Y, Hait WN, Yang JM. Phosphorylation of elongation factor-2 kinase differentially regulates the enzyme's stability under stress conditions. Biochem Biophys Res Commun 2012; 424:308-14. [PMID: 22749997 DOI: 10.1016/j.bbrc.2012.06.112] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2012] [Accepted: 06/21/2012] [Indexed: 01/17/2023]
Abstract
Eukaryotic elongation factor-2 kinase (eEF-2K) is a Ca(2+)/calmodulin-dependent enzyme that negatively regulates protein synthesis. eEF-2K has been shown to be up-regulated in cancer, and to play an important role in cell survival through inhibition of protein synthesis. Post-translational modification of protein synthesis machinery is important for its regulation and could be critical for survival of cancer cells encountering stress. The purpose of our study was to examine the regulation of eEF-2K during stress with a focus on the roles of phosphorylation in determining the stability of eEF-2K. We found that stress conditions (nutrient deprivation and hypoxia) increase eEF-2K protein. mRNA levels are only transiently increased and shortly return to normal, while eEF-2K protein levels continue to increase after further exposure to stress. A seemingly paradoxical decrease in eEF-2K stability was found when glioma cells were subjected to stress despite increased protein expression. We further demonstrated that phosphorylation of eEF-2K differentially affects the enzyme's turnover under both normal and stress conditions, as evidenced by the different half-lives of phosphorylation-defective mutants of eEF-2K. We further found that the eEF-2K site (Ser398) phosphorylated by AMPK is pivotal to the protein's stability, as the half-life of S398A mutant increases to greater than 24h under both normal and stress conditions. These data indicate that eEF-2K is regulated at multiple levels with phosphorylation playing a critical role in the enzyme's turnover under stressful conditions. The complexity of eEF-2K phosphorylation highlights the intricacies of protein synthesis control during cellular stress.
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Affiliation(s)
- Kathryn J Huber-Keener
- Department of Pharmacology and The Penn State Hershey Cancer Institute, The Pennsylvania State University College of Medicine and Milton S. Hershey Medical Center, 500 University Drive, Hershey, PA 17033, USA
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25
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Kruiswijk F, Yuniati L, Magliozzi R, Low TY, Lim R, Bolder R, Mohammed S, Proud CG, Heck AJR, Pagano M, Guardavaccaro D. Coupled activation and degradation of eEF2K regulates protein synthesis in response to genotoxic stress. Sci Signal 2012; 5:ra40. [PMID: 22669845 PMCID: PMC3812825 DOI: 10.1126/scisignal.2002718] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The kinase eEF2K [eukaryotic elongation factor 2 (eEF2) kinase] controls the rate of peptide chain elongation by phosphorylating eEF2, the protein that mediates the movement of the ribosome along the mRNA by promoting translocation of the transfer RNA from the A to the P site in the ribosome. eEF2K-mediated phosphorylation of eEF2 on threonine 56 (Thr⁵⁶) decreases its affinity for the ribosome, thereby inhibiting elongation. Here, we show that in response to genotoxic stress, eEF2K was activated by AMPK (adenosine monophosphate-activated protein kinase)-mediated phosphorylation on serine 398. Activated eEF2K phosphorylated eEF2 and induced a temporary ribosomal slowdown at the stage of elongation. Subsequently, during DNA damage checkpoint silencing, a process required to allow cell cycle reentry, eEF2K was degraded by the ubiquitin-proteasome system through the ubiquitin ligase SCF(βTrCP) (Skp1-Cul1-F-box protein, β-transducin repeat-containing protein) to enable rapid resumption of translation elongation. This event required autophosphorylation of eEF2K on a canonical βTrCP-binding domain. The inability to degrade eEF2K during checkpoint silencing caused sustained phosphorylation of eEF2 on Thr⁵⁶ and delayed the resumption of translation elongation. Our study therefore establishes a link between DNA damage signaling and translation elongation.
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Affiliation(s)
- Flore Kruiswijk
- Hubrecht Institute-KNAW and University Medical Center Utrecht, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands
| | - Laurensia Yuniati
- Hubrecht Institute-KNAW and University Medical Center Utrecht, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands
| | - Roberto Magliozzi
- Hubrecht Institute-KNAW and University Medical Center Utrecht, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands
| | - Teck Yew Low
- Biomolecular Mass Spectrometry and Proteomics Group, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
- The Netherlands Proteomics Center, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - Ratna Lim
- Hubrecht Institute-KNAW and University Medical Center Utrecht, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands
| | - Renske Bolder
- Hubrecht Institute-KNAW and University Medical Center Utrecht, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands
| | - Shabaz Mohammed
- Biomolecular Mass Spectrometry and Proteomics Group, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
- The Netherlands Proteomics Center, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - Christopher G. Proud
- School of Biological Sciences, School of Biological Sciences, Life Sciences Building, University of Southampton, Southampton SO17 1BJ, UK
| | - Albert J. R. Heck
- Biomolecular Mass Spectrometry and Proteomics Group, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
- The Netherlands Proteomics Center, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - Michele Pagano
- Department of Pathology, NYU Cancer Institute, New York University School of Medicine, 522 First Avenue, SRB1107, New York, NY 10016, USA
- Howard Hughes Medical Institute
| | - Daniele Guardavaccaro
- Hubrecht Institute-KNAW and University Medical Center Utrecht, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands
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Expression of elongation factor-2 kinase contributes to anoikis resistance and invasion of human glioma cells. Acta Pharmacol Sin 2011; 32:361-7. [PMID: 21278783 DOI: 10.1038/aps.2010.213] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
AIM To determine whether elongation factor-2 kinase (eEF-2 kinase) contributes to the malignant phenotype of glioblastoma multiforme by promoting the migration and invasion of glioma cells. The mechanism involved was also explored. METHODS Human glioma cell lines T98G and LN-229 were used. The expression of eEF-2 kinase was silenced using siRNA, and the invasive potential of tumor cells was assessed using a wound-healing assay and a Matrigel invasion assay. Apoptosis was determined using propidium iodide (PI) staining and Western blot analysis of cleaved caspase-3. RESULTS Silencing the expression of eEF-2 kinase by siRNA significantly suppressed both the migration and invasion of human glioma cells. Silencing eEF-2 kinase expression also sensitized glioma cells to anoikis, thereby decreasing tumor cell viability in the absence of attachment. Treatment of tumor cells with the caspase inhibitor z-VAD-fmk down-regulated Bim accumulation and abolished glioma cell sensitivity to anoikis. CONCLUSION The results suggest that the expression of eEF-2 kinase contributes to migration and invasion of human glioma cells by protecting them from anoikis. eEF-2 kinase expression may serve as a prognostic marker and a novel target for cancer therapy.
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Perraud AL, Zhao X, Ryazanov AG, Schmitz C. The channel-kinase TRPM7 regulates phosphorylation of the translational factor eEF2 via eEF2-k. Cell Signal 2010; 23:586-93. [PMID: 21112387 DOI: 10.1016/j.cellsig.2010.11.011] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2010] [Accepted: 11/17/2010] [Indexed: 01/11/2023]
Abstract
Protein translation is an essential but energetically expensive process, which is carefully regulated in accordance to the cellular nutritional and energy status. Eukaryotic elongation factor 2 (eEF2) is a central regulation point since it mediates ribosomal translocation and can be inhibited by phosphorylation at Thr56. TRPM7 is the unique fusion of an ion channel with a functional Ser/Thr-kinase. While TRPM7's channel function has been implicated in regulating vertebrate Mg(2+) uptake required for cell growth, the function of its kinase domain remains unclear. Here, we show that under conditions where cell growth is limited by Mg(2+) availability, TRPM7 via its kinase mediates enhanced Thr56 phosphorylation of eEF2. TRPM7-kinase does not appear to directly phosphorylate eEF2, but rather to influence the amount of eEF2's cognate kinase eEF2-k, involving its phosphorylation at Ser77. These findings suggest that TRPM7's structural duality ensures ideal positioning of its kinase in close proximity to channel-mediated Mg(2+) uptake, allowing for the adjustment of protein translational rates to the availability of Mg(2+).
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Affiliation(s)
- Anne-Laure Perraud
- Integrated Department of Immunology, National Jewish Health and University of Colorado Denver, CO 80206, USA.
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28
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Li X, Zhang Y, Xie P, Piao J, Hu Y, Chang M, Liu T, Hu L. Proteomic characterization of an isolated fraction of synthetic proteasome inhibitor (PSI)-induced inclusions in PC12 cells might offer clues to aggresomes as a cellular defensive response against proteasome inhibition by PSI. BMC Neurosci 2010; 11:95. [PMID: 20704702 PMCID: PMC2928238 DOI: 10.1186/1471-2202-11-95] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2009] [Accepted: 08/12/2010] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Cooperation of constituents of the ubiquitin proteasome system (UPS) with chaperone proteins in degrading proteins mediate a wide range of cellular processes, such as synaptic function and neurotransmission, gene transcription, protein trafficking, mitochondrial function and metabolism, antioxidant defence mechanisms, and apoptotic signal transduction. It is supposed that constituents of the UPS and chaperone proteins are recruited into aggresomes where aberrant and potentially cytotoxic proteins may be sequestered in an inactive form. RESULTS To determinate the proteomic pattern of synthetic proteasome inhibitor (PSI)-induced inclusions in PC12 cells after proteasome inhibition by PSI, we analyzed a fraction of PSI-induced inclusions. A proteomic feature of the isolated fraction was characterized by identification of fifty six proteins including twenty previously reported protein components of Lewy bodies, twenty eight newly identified proteins and eight unknown proteins. These proteins, most of which were recognized as a profile of proteins within cellular processes mediated by the UPS, a profile of constituents of the UPS and a profile of chaperone proteins, are classed into at least nine accepted categories. In addition, prolyl-4-hydroxylase beta polypeptide, an endoplasmic reticulum member of the protein disulfide isomerase family, was validated in the developmental process of PSI-induced inclusions in the cells. CONCLUSIONS It is speculated that proteomic characterization of an isolated fraction of PSI-induced inclusions in PC12 cells might offer clues to appearance of aggresomes serving as a cellular defensive response against proteasome inhibition.
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Affiliation(s)
- Xing'an Li
- Department of Neurology, The First Affiliated Hospital, Jilin University, Changchun, China
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29
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Andrieu C, Taieb D, Baylot V, Ettinger S, Soubeyran P, De-Thonel A, Nelson C, Garrido C, So A, Fazli L, Bladou F, Gleave M, Iovanna JL, Rocchi P. Heat shock protein 27 confers resistance to androgen ablation and chemotherapy in prostate cancer cells through eIF4E. Oncogene 2010; 29:1883-96. [DOI: 10.1038/onc.2009.479] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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30
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White-Gilbertson S, Kurtz DT, Voelkel-Johnson C. The role of protein synthesis in cell cycling and cancer. Mol Oncol 2009; 3:402-8. [PMID: 19546037 DOI: 10.1016/j.molonc.2009.05.003] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2009] [Revised: 05/04/2009] [Accepted: 05/25/2009] [Indexed: 01/08/2023] Open
Abstract
Cell cycling and protein synthesis are both key physiological tasks for cancer cells. Here we present a model for how the elongation phase of protein synthesis, governed by elongation factor 2 and elongation factor 2 kinase, both modulates and responds to cell cycling. Within this framework we also discuss survivin, a protein with both pro-mitotic and anti-apoptotic roles whose persistence in the cell is tied to protein synthesis due to its short half-life. Finally, we provide a brief overview of efforts of cancer researchers to target EF2 and EF2 kinase.
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Affiliation(s)
- Shai White-Gilbertson
- Department of Microbiology and Immunology, Medical University of South Carolina, Charleston, SC 29425, USA
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31
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Kirkland PA, Reuter CJ, Maupin-Furlow JA. Effect of proteasome inhibitor clasto-lactacystin-beta-lactone on the proteome of the haloarchaeon Haloferax volcanii. MICROBIOLOGY-SGM 2007; 153:2271-2280. [PMID: 17600071 DOI: 10.1099/mic.0.2007/005769-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Proteasomes play key roles in a variety of eukaryotic cell functions, including translation, transcription, metabolism, DNA repair and cell-cycle control. The biological functions of these multicatalytic proteases in archaea, however, are poorly understood. In this study, Haloferax volcanii was used as a model to determine the influence the proteasome-specific inhibitor clasto-lactacystin-beta-lactone (cLbetaL) has on archaeal proteome composition. Addition of 20-30 microM cLbetaL had a widespread effect on the proteome, with a 38-42 % increase in the number of 2-D gel electrophoresis (2-DE) protein spots, from an average of 627 to 1036 spots. Protein identities for 17 of the spots that were easily separated by 2-DE and unique and/or increased 2- to 14-fold in the cLbetaL-treated cells were determined by tandem mass spectrometry (MS/MS). These included protein homologues of the DJ-1/ThiJ family, mobilization of sulfur system, translation elongation factor EF-1 A, ribosomal proteins, tubulin-like FtsZ, divalent metal ABC transporter, dihydroxyacetone kinase DhaL, aldehyde dehydrogenase and 2-oxoacid decarboxylase E1beta. Based on these results, inhibition of H. volcanii proteasomes had a global influence on proteome composition, including proteins involved in central functions of the cell.
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Affiliation(s)
- P Aaron Kirkland
- Department of Microbiology and Cell Science, University of Florida, Gainesville, 32611, USA
| | - Christopher J Reuter
- Department of Microbiology and Cell Science, University of Florida, Gainesville, 32611, USA
| | - Julie A Maupin-Furlow
- Department of Microbiology and Cell Science, University of Florida, Gainesville, 32611, USA
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32
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White SJ, Kasman LM, Kelly MM, Lu P, Spruill L, McDermott PJ, Voelkel-Johnson C. Doxorubicin generates a proapoptotic phenotype by phosphorylation of elongation factor 2. Free Radic Biol Med 2007; 43:1313-21. [PMID: 17893044 PMCID: PMC2084083 DOI: 10.1016/j.freeradbiomed.2007.06.015] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/20/2007] [Revised: 06/21/2007] [Accepted: 06/23/2007] [Indexed: 11/24/2022]
Abstract
We have previously shown that doxorubicin sensitizes prostate cancer cells to tumor-necrosis-factor-related apoptosis-inducing ligand (TRAIL). Sensitization correlated with decreased expression of the antiapoptotic cellular FLICE-like inhibitor protein (cFLIP(S)). The decrease in cFLIP(S) could not be explained by transcriptional regulation or increased degradation, leading us to focus on translational mechanisms. In this study, we found that doxorubicin caused strong and sustained phosphorylation of elongation factor 2 (EF-2), which interferes with protein elongation. Phosphorylation of EF-2 appeared to occur in a kinase-independent manner. Treatment with hydrogen peroxide recapitulated the events observed after doxorubicin treatment. In addition, cells treated with hydrogen peroxide expressed less X-linked inhibitor of apoptosis protein (XIAP) and survivin which, like cFLIP(S), are short-half-life proteins with an antiapoptotic function while expression levels of DR5, caspases-8, -9, -3, and Bax are maintained. The doxorubicin-mediated decrease in cFLIP(S) and XIAP and the TRAIL-induced apoptosis were prevented by pretreatment with an iron chelator, indicating that expression of these proteins was affected by free radical generation upon interaction of iron with doxorubicin. In conclusion, our data suggest that free radicals can affect the phosphorylation of EF-2 resulting in a net loss of short-half-life proteins such as cFLIP(S) and XIAP, leaving a cell more vulnerable to apoptotic stimuli.
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Affiliation(s)
- Shai J. White
- Department of Microbiology & Immunology, Medical University of South Carolina, 173 Ashley Ave Charleston SC 29425, USA
| | - Laura M. Kasman
- Department of Microbiology & Immunology, Medical University of South Carolina, 173 Ashley Ave Charleston SC 29425, USA
| | - Margaret M. Kelly
- Hollings Cancer Center, Medical University of South Carolina, 173 Ashley Ave Charleston SC 29425, USA
| | - Ping Lu
- Department of Microbiology & Immunology, Medical University of South Carolina, 173 Ashley Ave Charleston SC 29425, USA
| | - Laura Spruill
- Department of Medicine, Division of Cardiology, Medical University of South Carolina, 173 Ashley Ave Charleston SC 29425, USA
| | - Paul J. McDermott
- Department of Medicine, Division of Cardiology, Medical University of South Carolina, 173 Ashley Ave Charleston SC 29425, USA
| | - Christina Voelkel-Johnson
- Department of Microbiology & Immunology, Medical University of South Carolina, 173 Ashley Ave Charleston SC 29425, USA
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Abstract
PURPOSE OF REVIEW Protein synthesis and degradation govern protein turnover, which underlies the adaptation of organisms to changing developmental, physiological and environmental needs. The cellular mechanisms of these processes have been increasingly uncovered. Recent findings establishing additional links between protein synthesis and degradation are the topic of this review. RECENT FINDINGS Several major developments in the field have taken place recently. First, the role of lysosomal-autophagosomal degradation, the established amino acid supplier for protein synthesis, has been demonstrated for additional diverse aspects of cellular physiology. Second, cytosolic protein degradation initiated by the proteasome has been assigned a critical role in sustaining ongoing protein synthesis upon acute nutrient restriction. A number of regulatory possibilities to modulate the intracellular amino acid flux by means of proteasomal degradation are discussed. Finally, the field of translation factor regulation by their degradation has emerged recently and is described here. SUMMARY The elucidation of mechanisms determining protein turnover and, thus, cellular adaptation will help us to understand the (patho)physiological conditions caused or accompanying acute and chronic nutrient deficiencies and should lead to new therapeutic strategies to handle them.
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Affiliation(s)
- Ramunas M Vabulas
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Martinsried, Germany.
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Calderón-Villalobos LIA, Nill C, Marrocco K, Kretsch T, Schwechheimer C. The evolutionarily conserved Arabidopsis thaliana F-box protein AtFBP7 is required for efficient translation during temperature stress. Gene 2006; 392:106-16. [PMID: 17240087 DOI: 10.1016/j.gene.2006.11.016] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2006] [Revised: 11/12/2006] [Accepted: 11/20/2006] [Indexed: 11/30/2022]
Abstract
In eukaryotes, E3 ubiquitin ligases (E3s) mediate the ubiquitylation of proteins that are destined for degradation by the ubiquitin-proteasome system. In SKP1/CDC53/F-box protein (SCF)-type E3 complexes, the interchangeable F-box protein confers specificity to the E3 ligase through direct physical interactions with the degradation substrate. The vast majority of the approximately 700 F-box proteins from the plant model organism Arabidopsis thaliana remain to be characterized. Here, we investigate the previously uncharacterized and evolutionarily conserved Arabidopsis F-box protein 7 (AtFBP7), which is encoded by a unique gene in Arabidopsis (At1g21760). Several apparent fbp7 loss-of-function alleles do not have an obvious phenotype. AtFBP7 is ubiquitously expressed and its expression is induced after cold and heat stress. When following up on a reported co-purification of the eukaryotic elongation factor-2 (eEF-2) with YLR097c, the apparent budding yeast orthologue of AtFBP7, we discovered a general defect in protein biosynthesis after cold and heat stress in fbp7 mutants. Thus, our findings suggest that AtFBP7 is required for protein synthesis during temperature stress.
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Affiliation(s)
- Luz Irina A Calderón-Villalobos
- Department of Developmental Genetics, Centre for Plant Molecular Biology, Tübingen University, Auf der Morgenstelle 5, 72076 Tübingen, Germany
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Olivier S, Robe P, Bours V. Can NF-κB be a target for novel and efficient anti-cancer agents? Biochem Pharmacol 2006; 72:1054-68. [PMID: 16973133 DOI: 10.1016/j.bcp.2006.07.023] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2006] [Revised: 07/20/2006] [Accepted: 07/24/2006] [Indexed: 12/23/2022]
Abstract
Since the discovery of the NF-kappaB transcription factor in 1986 and the cloning of the genes coding for NF-kappaB and IkappaB proteins, many studies demonstrated that this transcription factor can, in most cases, protect transformed cells from apoptosis and therefore participate in the onset or progression of many human cancers. Molecular studies demonstrated that ancient widely used drugs, known for their chemopreventive or therapeutic activities against human cancers, inhibit NF-kappaB, usually among other biological effects. It is therefore considered that the anti-cancer activities of NSAIDs (non-steroidal anti-inflammatory drugs) or glucocorticoids are probably partially related to the inhibition of NF-kappaB and new clinical trials are being initiated with old compounds such as sulfasalazine. In parallel, many companies have developed novel agents acting on the NF-kappaB pathway: some of these agents are supposed to be NF-kappaB specific (i.e. IKK inhibitors) while others have wide-range biological activities (i.e. proteasome inhibitors). Today, the most significant clinical data have been obtained with bortezomib, a proteasome inhibitor, for the treatment of multiple myeloma. This review discusses the preclinical and clinical data obtained with these various drugs and their putative future developments.
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Affiliation(s)
- Sabine Olivier
- Department of Rheumatology, Centre for Biomedical Integrative Genoproteomics, University of Liège, CHU B35, Sart-Tilman, 4000 Liège, Belgium
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Chang YS, Lo CW, Sun FC, Chang MDT, Lai YK. Differential expression of Hsp90 isoforms in geldanamycin-treated 9L cells. Biochem Biophys Res Commun 2006; 344:37-44. [PMID: 16630568 DOI: 10.1016/j.bbrc.2006.03.157] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2006] [Accepted: 03/24/2006] [Indexed: 12/20/2022]
Abstract
In mammals, two major Hsp90 isoforms (Hsp90alpha and Hsp90beta) have been identified and found to be highly conserved among different species. However, the expression control of Hsp90 isoforms at both transcriptional and translational levels is largely unknown. Herein, we quantitatively investigate the changes in the total mRNA and inductive protein levels of Hsp90alpha and Hsp90beta in rat gliosarcoma cells treated with geldanamycin (GA). The stability of mRNA and protein was estimated. The translational efficiency of Hsp90 isoforms was measured employing in vitro translation techniques. It was found that Hsp90alpha was more inducible than Hsp90beta after GA treatment, whereas the hsp90alpha mRNA level was lower than that of hsp90beta. In addition, higher translational efficiency of hsp90alpha mRNA was observed, suggesting that translational control played an important role. Taken together, our results indicate that differential expression between Hsp90alpha and Hsp90beta is a consequence of both distinct mRNA profiles and differential translation processes.
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Affiliation(s)
- Yuo-Sheng Chang
- Institute of Biotechnology, Department of Life Science, National Tsing Hua University, Hsinchu, Taiwan 30013, ROC
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Connolly E, Braunstein S, Formenti S, Schneider RJ. Hypoxia inhibits protein synthesis through a 4E-BP1 and elongation factor 2 kinase pathway controlled by mTOR and uncoupled in breast cancer cells. Mol Cell Biol 2006; 26:3955-65. [PMID: 16648488 PMCID: PMC1489005 DOI: 10.1128/mcb.26.10.3955-3965.2006] [Citation(s) in RCA: 177] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Hypoxia is a state of low oxygen availability that limits tumor growth. The mechanism of protein synthesis inhibition by hypoxia and its circumvention by transformation are not well understood. Hypoxic breast epithelial cells are shown to downregulate protein synthesis by inhibition of the kinase mTOR, which suppresses mRNA translation through a novel mechanism mitigated in transformed cells: disruption of proteasome-targeted degradation of eukaryotic elongation factor 2 (eEF2) kinase and activation of the regulatory protein 4E-BP1. In transformed breast epithelial cells under hypoxia, the mTOR and S6 kinases are constitutively activated and the mTOR negative regulator tuberous sclerosis complex 2 (TSC2) protein fails to function. Gene silencing of 4E-BP1 and eEF2 kinase or TSC2 confers resistance to hypoxia inhibition of protein synthesis in immortalized breast epithelial cells. Breast cancer cells therefore acquire resistance to hypoxia by uncoupling oxygen-responsive signaling pathways from mTOR function, eliminating inhibition of protein synthesis mediated by 4E-BP1 and eEF2.
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MESH Headings
- Adaptor Proteins, Signal Transducing/genetics
- Adaptor Proteins, Signal Transducing/metabolism
- Blotting, Western
- Breast Neoplasms/genetics
- Breast Neoplasms/metabolism
- Breast Neoplasms/pathology
- Carcinoma, Intraductal, Noninfiltrating/metabolism
- Carcinoma, Intraductal, Noninfiltrating/pathology
- Cell Cycle Proteins
- Cell Line, Transformed
- Cell Line, Tumor
- Enzyme Activation
- Female
- Gene Silencing
- Humans
- Hypoxia/physiopathology
- Methionine/metabolism
- Peptide Elongation Factor 2/genetics
- Peptide Elongation Factor 2/metabolism
- Phosphoproteins/genetics
- Phosphoproteins/metabolism
- Phosphorylation
- Precipitin Tests
- Protein Kinases/physiology
- RNA Interference
- RNA, Small Interfering/metabolism
- Retroviridae/genetics
- Ribosomal Protein S6 Kinases/metabolism
- Signal Transduction
- Sulfur Radioisotopes
- TOR Serine-Threonine Kinases
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Affiliation(s)
- Eileen Connolly
- Department of Microbiology, New York University School of Medicine, New York, New York 10016, USA
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Schmitt HP. Protein ubiquitination, degradation and the proteasome in neuro-degenerative disorders: no clear evidence for a significant pathogenetic role of proteasome failure in Alzheimer disease and related disorders. Med Hypotheses 2006; 67:311-7. [PMID: 16580788 DOI: 10.1016/j.mehy.2006.02.023] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2006] [Revised: 02/16/2006] [Accepted: 02/17/2006] [Indexed: 11/20/2022]
Abstract
It has recently been proposed that Alzheimer disease (AD) might be initiated by a molecular 'hit' into a regulatory protein, e.g. a cell surface receptor [Schmitt HP. Neuro-modulation, aminergic neuro-disinhibition and neuro-degeneration: draft of a comprehensive theory for Alzheimer disease. Med Hypoth 2005;65:1106-19]. However, other substrates, in particular intra-cellular protein complexes such as the ubiquitin/proteasome system (UPS) could as well serve as a targets for such a 'hit' which might insert a mutation or induce conformational changes resulting in functional failure of protein degradation along the ubiquitin/proteasome proteolytic pathway. It has been claimed that impairment of the large multi-catalytic protease complex, the 20S/26S proteasome, might represent a key factor in the early pathogenesis of neuro-degenerative disorders characterized by the formation of abnormal protein aggregates such as neuronal cytoplasmic or nuclear inclusion bodies and fibrillary deposits. This article aims to review critically whether current information really supports the idea that impairment of the UPS might play a significant role in the early pathogenesis of neuro-degenerative disorders, with special emphasis on AD. The data provided in favour of proteasome impairment were, as a rule, revealed in in vitro experiments which cannot be unequivocally transferred to the in vivo conditions in neuro-degeneration. The author concludes that there is yet no clear evidence of a pivotal role of proteasome failure in the early pathogenesis of AD.
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Affiliation(s)
- H Peter Schmitt
- Institute of Pathology, Department for Neuropathology, University of Heidelberg, Im Neuernheimer Feld 220-221, 69120 Heidelberg, Germany.
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Abstract
PURPOSE OF REVIEW Proteasome inhibitors are a novel class of drugs that alter normal cellular control of apoptosis. As such, they are being investigated as novel therapies to alter uncontrolled cellular proliferation and treat cancers. This review explores new information about how the proteasome regulates apoptosis and how proteasome inhibitors can be exploited as anti-tumor drugs. RECENT FINDINGS Proteasome inhibitors block the activation of nuclear factor kappa B in a number of cell systems, as well as altering apoptotic regulatory proteins and intracellular signals that influence the fate of the cell. These effects are true for many tumor cell lines. The US Food and Drug Administration-approved proteasome inhibitor bortezomib blocks erroneous cell proliferation and induces apoptosis in many tumor models. SUMMARY Proteasome inhibitors have demonstrated promise in vitro, and as a result clinical trials have begun to investigate these agents as therapy for numerous human cancers. Furthermore, newer agents are being designed to inhibit the proteasome system and exert further anti-tumor activity.
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Affiliation(s)
- Stacey R Vlahakis
- Mayo Clinic College of Medicine, Division of Infectious Diseases, Rochester, Minnesota, USA
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Falsone SF, Gesslbauer B, Tirk F, Piccinini AM, Kungl AJ. A proteomic snapshot of the human heat shock protein 90 interactome. FEBS Lett 2005; 579:6350-4. [PMID: 16263121 DOI: 10.1016/j.febslet.2005.10.020] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2005] [Revised: 10/10/2005] [Accepted: 10/12/2005] [Indexed: 01/12/2023]
Abstract
Heat shock protein 90 (Hsp90) is a molecular chaperone which modulates several signalling pathways within a cell. By applying co-immunoprecipitation with endogeneous Hsp90, we were able to identify 39 novel protein interaction partners of this chaperone in human embryonic kidney cells (HEK293). Interestingly, levels of DNA-activated protein kinase catalytic subunit, an Hsp90 interaction partner found in this study, were found to be sensitive to Hsp90 inhibitor treatment only in HeLa cells but not in HEK293 cells referring to the tumorgenicity of this chaperone.
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Affiliation(s)
- S Fabio Falsone
- Institute of Pharmaceutical Sciences, University of Graz, Universitätsplatz 1, 8010 Graz, Austria
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