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Wang P, Li Z, Kim SH, Xu H, Huang H, Yang C, Snape A, Choi JH, Bermudez S, Boivin MN, Ferry N, Karamchandani J, Nagar B, Sonenberg N. PPM1G dephosphorylates eIF4E in control of mRNA translation and cell proliferation. Life Sci Alliance 2024; 7:e202402755. [PMID: 39111820 PMCID: PMC11306785 DOI: 10.26508/lsa.202402755] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2024] [Revised: 07/29/2024] [Accepted: 07/30/2024] [Indexed: 08/10/2024] Open
Abstract
The mRNA 5'cap-binding eukaryotic translation initiation factor 4E (eIF4E) plays a critical role in the control of mRNA translation in health and disease. One mechanism of regulation of eIF4E activity is via phosphorylation of eIF4E by MNK kinases, which promotes the translation of a subset of mRNAs encoding pro-tumorigenic proteins. Work on eIF4E phosphatases has been paltry. Here, we show that PPM1G is the phosphatase that dephosphorylates eIF4E. We describe the eIF4E-binding motif in PPM1G that is similar to 4E-binding proteins (4E-BPs). We demonstrate that PPM1G inhibits cell proliferation by targeting phospho-eIF4E-dependent mRNA translation.
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Affiliation(s)
- Peng Wang
- https://ror.org/01pxwe438 Department of Biochemistry and Goodman Cancer Institute, McGill University, Montreal, Canada
- Clinical Biological Imaging and Genetic (C-BIG) Repository, Montreal Neurological Institute-Hospital, Montreal, Canada
| | - Zixian Li
- https://ror.org/01pxwe438 Department of Biochemistry, Francesco Bellini Life Sciences Building, McGill University, Montreal, Canada
| | - Sung-Hoon Kim
- https://ror.org/01pxwe438 Department of Biochemistry and Goodman Cancer Institute, McGill University, Montreal, Canada
| | - Haijin Xu
- https://ror.org/01pxwe438 Department of Physiology, McIntyre Medical Sciences Building, McGill University, Montreal, Canada
| | - Hao Huang
- https://ror.org/01pxwe438 Department of Biochemistry and Goodman Cancer Institute, McGill University, Montreal, Canada
| | - Chutong Yang
- https://ror.org/01pxwe438 Department of Biochemistry and Goodman Cancer Institute, McGill University, Montreal, Canada
| | - Abby Snape
- https://ror.org/01pxwe438 Department of Biochemistry and Goodman Cancer Institute, McGill University, Montreal, Canada
| | - Jung-Hyun Choi
- https://ror.org/01pxwe438 Department of Biochemistry and Goodman Cancer Institute, McGill University, Montreal, Canada
| | - Sara Bermudez
- https://ror.org/01pxwe438 Department of Biochemistry and Goodman Cancer Institute, McGill University, Montreal, Canada
| | - Marie-Noelle Boivin
- Clinical Biological Imaging and Genetic (C-BIG) Repository, Montreal Neurological Institute-Hospital, Montreal, Canada
| | - Nicolas Ferry
- Clinical Biological Imaging and Genetic (C-BIG) Repository, Montreal Neurological Institute-Hospital, Montreal, Canada
| | - Jason Karamchandani
- Clinical Biological Imaging and Genetic (C-BIG) Repository, Montreal Neurological Institute-Hospital, Montreal, Canada
| | - Bhushan Nagar
- https://ror.org/01pxwe438 Department of Biochemistry, Francesco Bellini Life Sciences Building, McGill University, Montreal, Canada
| | - Nahum Sonenberg
- https://ror.org/01pxwe438 Department of Biochemistry and Goodman Cancer Institute, McGill University, Montreal, Canada
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Song M, Xu M, Zhang Q, Fan T, Xu J, Hang C, Cheng C, Ou X, Gong C, Lu Q. PPM1G promotes autophagy and progression of pancreatic cancer via upregulating HMGB1. Cell Signal 2024:111342. [PMID: 39121976 DOI: 10.1016/j.cellsig.2024.111342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2024] [Revised: 07/24/2024] [Accepted: 08/06/2024] [Indexed: 08/12/2024]
Abstract
Pancreatic cancer remains one of the most aggressive and lethal malignancies worldwide, with a dismal 5-year relative survival rates of only 12%. Therefore, it is urgent to discover the key molecular markers to improve the therapeutic outcomes in pancreatic cancer. Herein, we first demonstrated that PPM1G is upregulated in pancreatic cancer and that PPM1G depletion decreases pancreatic cancer cell growth in vitro and in vivo. High PPM1G expression was linked to short overall survival of pancreatic cancer patients, which was further validated in the TCGA database. Moreover, by detecting Beclin 1, LC3-II, and SQSTM1/p62 expressions and observing autolysosome under transmission electron microscope, we discovered that PPM1G is a novel positive regulator of macroautophagy/autophagy. Furthermore, by using immunoprecipitation-mass spectrometry (IP-MS) analysis and following systemic molecular biology experiment, we demonstrated PPM1G promotes the autophagy and proliferation of pancreatic cancer by directly upregulating HMGB1. Additionally, patients with both high PPM1G and high HMGB1 exhibited poorer prognosis in our cohort. This study preliminarily investigated the possibility of PPM1G as a potential therapeutic target and prognostic biomarker in pancreatic cancer patients.
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Affiliation(s)
- Mingyang Song
- Department of Gastroenterology, Zhongda Hospital, School of Medicine, Southeast University, Nanjing 210009, China; Department of Gastroenterology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou 450000, China
| | - Min Xu
- Department of Human Anatomy, School of Medicine, Southeast University, Nanjing 210009, China
| | - Qi Zhang
- Department of Gastroenterology, Zhongda Hospital, School of Medicine, Southeast University, Nanjing 210009, China
| | - Tingyu Fan
- Department of Gastroenterology, Zhongda Hospital, School of Medicine, Southeast University, Nanjing 210009, China
| | - Jiajia Xu
- Department of Clinical Pathology, Zhongda Hospital, Southeast University, Nanjing 210009, China
| | - Cheng Hang
- Department of Gastroenterology, Taicang Affiliated Hospital of Soochow University, The First People's Hospital of Taicang, Jiangsu 215400, China
| | - Cuie Cheng
- Department of Gastroenterology, Affiliated Changshu Hospital of Nantong University, Suzhou 215500, China
| | - Xilong Ou
- Department of Gastroenterology, Zhongda Hospital, School of Medicine, Southeast University, Nanjing 210009, China.
| | - Chen Gong
- Department of Gastroenterology, Taicang Affiliated Hospital of Soochow University, The First People's Hospital of Taicang, Jiangsu 215400, China.
| | - Qin Lu
- Department of Gastroenterology, Zhongda Hospital, School of Medicine, Southeast University, Nanjing 210009, China.
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Li C, Yi Y, Ouyang Y, Chen F, Lu C, Peng S, Wang Y, Chen X, Yan X, Xu H, Li S, Feng L, Xie X. TORSEL, a 4EBP1-based mTORC1 live-cell sensor, reveals nutrient-sensing targeting by histone deacetylase inhibitors. Cell Biosci 2024; 14:68. [PMID: 38824577 PMCID: PMC11143692 DOI: 10.1186/s13578-024-01250-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2024] [Accepted: 05/21/2024] [Indexed: 06/03/2024] Open
Abstract
BACKGROUND Mammalian or mechanistic target of rapamycin complex 1 (mTORC1) is an effective therapeutic target for diseases such as cancer, diabetes, aging, and neurodegeneration. However, an efficient tool for monitoring mTORC1 inhibition in living cells or tissues is lacking. RESULTS We developed a genetically encoded mTORC1 sensor called TORSEL. This sensor changes its fluorescence pattern from diffuse to punctate when 4EBP1 dephosphorylation occurs and interacts with eIF4E. TORSEL can specifically sense the physiological, pharmacological, and genetic inhibition of mTORC1 signaling in living cells and tissues. Importantly, TORSEL is a valuable tool for imaging-based visual screening of mTORC1 inhibitors. Using TORSEL, we identified histone deacetylase inhibitors that selectively block nutrient-sensing signaling to inhibit mTORC1. CONCLUSIONS TORSEL is a unique living cell sensor that efficiently detects the inhibition of mTORC1 activity, and histone deacetylase inhibitors such as panobinostat target mTORC1 signaling through amino acid sensing.
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Affiliation(s)
- Canrong Li
- School of Medicine, Shenzhen Campus of Sun Yat-sen University, Sun Yat-sen University, Shenzhen, China
| | - Yuguo Yi
- School of Medicine, Shenzhen Campus of Sun Yat-sen University, Sun Yat-sen University, Shenzhen, China
| | - Yingyi Ouyang
- School of Medicine, Shenzhen Campus of Sun Yat-sen University, Sun Yat-sen University, Shenzhen, China
| | - Fengzhi Chen
- School of Medicine, Shenzhen Campus of Sun Yat-sen University, Sun Yat-sen University, Shenzhen, China
| | - Chuxin Lu
- School of Medicine, Shenzhen Campus of Sun Yat-sen University, Sun Yat-sen University, Shenzhen, China
| | - Shujun Peng
- School of Medicine, Shenzhen Campus of Sun Yat-sen University, Sun Yat-sen University, Shenzhen, China
| | - Yifan Wang
- School of Medicine, Shenzhen Campus of Sun Yat-sen University, Sun Yat-sen University, Shenzhen, China
| | - Xinyu Chen
- School of Medicine, Shenzhen Campus of Sun Yat-sen University, Sun Yat-sen University, Shenzhen, China
| | - Xiao Yan
- School of Medicine, Shenzhen Campus of Sun Yat-sen University, Sun Yat-sen University, Shenzhen, China
| | - Haolun Xu
- School of Medicine, Shenzhen Campus of Sun Yat-sen University, Sun Yat-sen University, Shenzhen, China
| | - Shuiming Li
- College of Life Sciences and Oceanography, Shenzhen Key Laboratory of Microbial Genetic Engineering, Shenzhen University, Shenzhen, China
| | - Lin Feng
- Department of Experimental Research, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangzhou, China
| | - Xiaoduo Xie
- School of Medicine, Shenzhen Campus of Sun Yat-sen University, Sun Yat-sen University, Shenzhen, China.
- Department of Experimental Research, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangzhou, China.
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Hu W, Ma SL, Qiong L, Du Y, Gong LP, Pan YH, Sun LP, Wen JY, Chen JN, Guan XY, Shao CK. PPM1G promotes cell proliferation via modulating mutant GOF p53 protein expression in hepatocellular carcinoma. iScience 2024; 27:109116. [PMID: 38384839 PMCID: PMC10879691 DOI: 10.1016/j.isci.2024.109116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Revised: 11/25/2023] [Accepted: 01/31/2024] [Indexed: 02/23/2024] Open
Abstract
The serine/threonine protein phosphatase family involves series of cellular processes, such as pre-mRNA splicing. The function of one of its members, protein phosphatase, Mg2+/Mn2+ dependent 1G (PPM1G), remains unclear in hepatocellular carcinoma (HCC). Our results demonstrated that PPM1G was significantly overexpressed in HCC cells and tumor tissues compared with the normal liver tissues at both protein and RNA levels. High PPM1G expression is associated with shorter overall survival (p < 0.0001) and disease-free survival (p = 0.004) in HCC patients. Enhanced expression of PPM1G increases the cell proliferation rate, and knockdown of PPM1G led to a significant reduction in tumor volume in vivo. Further experiments illustrated that upregulated-PPM1G expression increased the protein expression of gain-of-function (GOF) mutant p53. Besides, the immunoprecipitation analysis revealed a direct interaction between PPM1G and GOF mutant p53. Collectively, PPM1G can be a powerful prognostic predictor and potential drug-target molecule.
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Affiliation(s)
- Wen Hu
- Department of Pathology, The Third Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong 510630, China
| | - Shao-Lin Ma
- Department of Gynecological Oncology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, Guangdong 510120, China
| | - Liang Qiong
- Department of Pathology, The Third Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong 510630, China
| | - Yu Du
- Department of Pathology, The Third Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong 510630, China
| | - Li-Ping Gong
- Department of Pathology, The Third Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong 510630, China
| | - Yu-Hang Pan
- Department of Pathology, The Third Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong 510630, China
| | - Li-Ping Sun
- Department of Pathology, The Third Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong 510630, China
| | - Jing-Yun Wen
- Department of Oncology, The Third Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong 510630, China
| | - Jian-Ning Chen
- Department of Pathology, The Third Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong 510630, China
| | - Xin-Yuan Guan
- State Key Laboratory of Oncology in South China, Sun Yat-sen University Cancer Center, Guangzhou, Guangdong 510060, China
- Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangzhou, Guangdong 510060, China
- Department of Clinical Oncology, the University of Hong Kong, Hong Kong, China
| | - Chun-Kui Shao
- Department of Pathology, The Third Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong 510630, China
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Peng D, Huang Z, Yang H, Luo Y, Wu Z. PPM1G regulates hepatic ischemia/reperfusion injury through STING-mediated inflammatory pathways in macrophages. Immun Inflamm Dis 2024; 12:e1189. [PMID: 38372470 PMCID: PMC10875902 DOI: 10.1002/iid3.1189] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Revised: 01/08/2024] [Accepted: 02/04/2024] [Indexed: 02/20/2024] Open
Abstract
BACKGROUND Ischemia/reperfusion injury (IRI) is generally unavoidable following liver transplantation. Here, we investigated the role of protein phosphatase, Mg2+ /Mn2+ dependent 1G (PPM1G) in hepatic IRI. METHODS Hepatic IRI was mimicked by employing a hypoxia/reperfusion (H/R) model in RAW 264.7 cells and a 70% warm ischemia model in C57BL/6 mice, respectively. In vitro, expression changes of tumor necrosis factor-α and interleukin were detected by quantitative real-time polymerase chain reaction (qRT-PCR), western blot analysis, and enzyme-linked immunosorbent assay. The protein expressions of PPM1G and the stimulator of interferon genes (STING) pathway components were analyzed by western blot. Interaction between PPM1G and STING was verified by coimmunoprecipitation (CO-IP). Immunofluorescence was applied for detection of p-IRF3. Flow cytometry, qRT-PCR and western blot were utilized to analyze markers of macrophage polarization. In vivo, histological analyses of mice liver were carried out by TUNEL and H&E staining. Changes in serum aminotransferases were also detected. RESULTS Following H/R intervention, a steady decline in PPM1G along with an increase in inflammatory cytokines in vitro was observed. Addition of plasmid with PPM1G sequence limited the release of inflammatory cytokines and downregulated phosphorylation of STING. CO-IP validated the interaction between PPM1G and STING. Furthermore, inhibition of PPM1G with lentivirus enhanced phosphorylation of STING and its downstream components; meanwhile, p65, p38, and Jnk were also surged to phosphorylation. Expression of INOS and CD86 was surged, while CD206, Arg-1, and IL-10 were inhibited. In vivo, PPM1G inhibition further promoted liver damage, hepatocyte apoptosis, and transaminases release. Selective inhibition of STING with C-176 partially reversed the activation of STING pathway and inflammatory cytokines in vitro. M1 markers were also suppressed by C-176. In vivo, C-176 rescued liver damage and transaminase release caused by PPM1G inhibition. CONCLUSION PPM1G suppresses hepatic IRI and macrophage M1 phenotype by repressing STING-mediated inflammatory pathways.
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Affiliation(s)
- Dadi Peng
- Department of Hepatobiliary SurgeryThe First Affiliated Hospital of Chongqing Medical UniversityChongqingChina
| | - Zuotian Huang
- Department of Hepatobiliary Pancreatic Tumor CenterChongqing University Cancer HospitalChongqingChina
| | - Hang Yang
- Department of Hepatobiliary SurgeryThe First Affiliated Hospital of Chongqing Medical UniversityChongqingChina
| | - Yunhai Luo
- Department of Hepatobiliary SurgeryThe First Affiliated Hospital of Chongqing Medical UniversityChongqingChina
| | - Zhongjun Wu
- Department of Hepatobiliary SurgeryThe First Affiliated Hospital of Chongqing Medical UniversityChongqingChina
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Ma X, Li Q, Chen G, Xie J, Wu M, Meng F, Liu J, Liu Y, Zhao D, Wang W, Wang D, Liu C, Dai J, Li C, Cui M. Role of Hippocampal miR-132-3p in Modifying the Function of Protein Phosphatase Mg2+/Mn2+-dependent 1 F in Depression. Neurochem Res 2023:10.1007/s11064-023-03926-8. [PMID: 37036545 DOI: 10.1007/s11064-023-03926-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Revised: 03/15/2023] [Accepted: 03/28/2023] [Indexed: 04/11/2023]
Abstract
Depression is a common, severe, and debilitating psychiatric disorder of unclear etiology. Our previous study has shown that protein phosphatase Mg2+/Mn2+-dependent 1F (PPM1F) in the hippocampal dentate gyrus (DG) displays significant regulatory effects in depression-related behaviors. miR-132-3p plays a potential role in the etiology of depression. This study explored the effect of miR-132-3p on the onset of depression and the possible underlying mechanism for modulating PPM1F expression during the pathology of depression. We found that miR-132-3p levels in the hippocampus of depressed mice subjected to chronic unpredictable stress (CUS) were dramatically reduced, which were correlated with depression-related behaviors. Knockdown of miR-132-3p in hippocampal DG resulted in depression-related phenotypes and increased susceptibility to stress. miR-132-3p overexpression in hippocampal DG alleviated CUS-induced depression-related performance. We then screened out the potential target genes of miR-132-3p, and we found that the expression profiles of sterol regulatory element-binding transcription factor 1 (Srebf1) and forkhead box protein O3a (FOXO3a) were positively correlated with PPM1F under the condition of miR-132-3p knockdown. Finally, as anticipated, we revealed that the activities of Ca2+/calmodulin-dependent protein kinase II (CAMKII) and adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK) were reduced, which underlies the target signaling pathway of PPM1F. In conclusion, our study suggests that miR-132-3p was designed to regulate depression-related behaviors by indirectly regulating PPM1F and targeting Srebf1 and FOXO3a, which have been linked to the pathogenesis and treatment of depression.
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Affiliation(s)
- Xiangxian Ma
- Department of Psychology, Binzhou Medical University Hospital, No. 661 Huanghe 2nd Road, Binzhou, Shandong, 256603, China
- Medical research center, Binzhou Medical University Hospital, No. 661 Huanghe 2nd Road, Binzhou, Shandong, 256603, China
- Institute for Metabolic & Neuropsychiatric Disorders, Binzhou Medical University Hospital, Binzhou, Shandong, China
| | - Qiongyu Li
- Medical research center, Binzhou Medical University Hospital, No. 661 Huanghe 2nd Road, Binzhou, Shandong, 256603, China
- Institute for Metabolic & Neuropsychiatric Disorders, Binzhou Medical University Hospital, Binzhou, Shandong, China
- Department of Gastroenterology, Binzhou Medical University Hospital, Binzhou, Shandong, China
| | - Guanhong Chen
- Medical research center, Binzhou Medical University Hospital, No. 661 Huanghe 2nd Road, Binzhou, Shandong, 256603, China
- Institute for Metabolic & Neuropsychiatric Disorders, Binzhou Medical University Hospital, Binzhou, Shandong, China
- The first clinical medical college, Binzhou Medical University, Yantai, Shandong, China
| | - Junjie Xie
- Medical research center, Binzhou Medical University Hospital, No. 661 Huanghe 2nd Road, Binzhou, Shandong, 256603, China
- Institute for Metabolic & Neuropsychiatric Disorders, Binzhou Medical University Hospital, Binzhou, Shandong, China
- The first clinical medical college, Binzhou Medical University, Yantai, Shandong, China
| | - Min Wu
- Medical research center, Binzhou Medical University Hospital, No. 661 Huanghe 2nd Road, Binzhou, Shandong, 256603, China
- Institute for Metabolic & Neuropsychiatric Disorders, Binzhou Medical University Hospital, Binzhou, Shandong, China
- Department of Neurosurgery, Binzhou Medical University Hospital, Binzhou, Shandong, China
| | - Fantao Meng
- Department of Psychology, Binzhou Medical University Hospital, No. 661 Huanghe 2nd Road, Binzhou, Shandong, 256603, China
- Medical research center, Binzhou Medical University Hospital, No. 661 Huanghe 2nd Road, Binzhou, Shandong, 256603, China
- Institute for Metabolic & Neuropsychiatric Disorders, Binzhou Medical University Hospital, Binzhou, Shandong, China
| | - Jing Liu
- Department of Psychology, Binzhou Medical University Hospital, No. 661 Huanghe 2nd Road, Binzhou, Shandong, 256603, China
- Medical research center, Binzhou Medical University Hospital, No. 661 Huanghe 2nd Road, Binzhou, Shandong, 256603, China
- Institute for Metabolic & Neuropsychiatric Disorders, Binzhou Medical University Hospital, Binzhou, Shandong, China
| | - Yong Liu
- Medical research center, Binzhou Medical University Hospital, No. 661 Huanghe 2nd Road, Binzhou, Shandong, 256603, China
- Institute for Metabolic & Neuropsychiatric Disorders, Binzhou Medical University Hospital, Binzhou, Shandong, China
- Department of Physiology, Binzhou Medical University, Shandong, China
| | - Di Zhao
- Department of Psychology, Binzhou Medical University Hospital, No. 661 Huanghe 2nd Road, Binzhou, Shandong, 256603, China
- Medical research center, Binzhou Medical University Hospital, No. 661 Huanghe 2nd Road, Binzhou, Shandong, 256603, China
- Institute for Metabolic & Neuropsychiatric Disorders, Binzhou Medical University Hospital, Binzhou, Shandong, China
| | - Wentao Wang
- Department of Psychology, Binzhou Medical University Hospital, No. 661 Huanghe 2nd Road, Binzhou, Shandong, 256603, China
- Medical research center, Binzhou Medical University Hospital, No. 661 Huanghe 2nd Road, Binzhou, Shandong, 256603, China
- Institute for Metabolic & Neuropsychiatric Disorders, Binzhou Medical University Hospital, Binzhou, Shandong, China
| | - Dan Wang
- Department of Psychology, Binzhou Medical University Hospital, No. 661 Huanghe 2nd Road, Binzhou, Shandong, 256603, China
- Medical research center, Binzhou Medical University Hospital, No. 661 Huanghe 2nd Road, Binzhou, Shandong, 256603, China
- Institute for Metabolic & Neuropsychiatric Disorders, Binzhou Medical University Hospital, Binzhou, Shandong, China
| | - Cuilan Liu
- Department of Psychology, Binzhou Medical University Hospital, No. 661 Huanghe 2nd Road, Binzhou, Shandong, 256603, China
- Medical research center, Binzhou Medical University Hospital, No. 661 Huanghe 2nd Road, Binzhou, Shandong, 256603, China
- Institute for Metabolic & Neuropsychiatric Disorders, Binzhou Medical University Hospital, Binzhou, Shandong, China
| | - Juanjuan Dai
- Department of Psychology, Binzhou Medical University Hospital, No. 661 Huanghe 2nd Road, Binzhou, Shandong, 256603, China
- Medical research center, Binzhou Medical University Hospital, No. 661 Huanghe 2nd Road, Binzhou, Shandong, 256603, China
- Institute for Metabolic & Neuropsychiatric Disorders, Binzhou Medical University Hospital, Binzhou, Shandong, China
| | - Chen Li
- Department of Psychology, Binzhou Medical University Hospital, No. 661 Huanghe 2nd Road, Binzhou, Shandong, 256603, China.
- Medical research center, Binzhou Medical University Hospital, No. 661 Huanghe 2nd Road, Binzhou, Shandong, 256603, China.
- Institute for Metabolic & Neuropsychiatric Disorders, Binzhou Medical University Hospital, Binzhou, Shandong, China.
| | - Minghu Cui
- Department of Psychology, Binzhou Medical University Hospital, No. 661 Huanghe 2nd Road, Binzhou, Shandong, 256603, China.
- Medical research center, Binzhou Medical University Hospital, No. 661 Huanghe 2nd Road, Binzhou, Shandong, 256603, China.
- Institute for Metabolic & Neuropsychiatric Disorders, Binzhou Medical University Hospital, Binzhou, Shandong, China.
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Wang C, Yao C, Sun Y, Chen J, Ge Y, Wang Y, Wang F, Wang L, Lin Y, Yao S. Identification and verification of a novel epigenetic-related gene signature for predicting the prognosis of hepatocellular carcinoma. Front Genet 2022; 13:897123. [DOI: 10.3389/fgene.2022.897123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Accepted: 11/14/2022] [Indexed: 12/05/2022] Open
Abstract
Hepatocellular carcinoma (HCC) is a common malignant tumor with a poor prognosis. Epigenetic dysregulation is now considered to be related to hepatocarcinogenesis. However, it is unclear how epigenetic-related genes (ERGs) contribute to the prognosis of HCC. In this study, we used the TCGA database to identify prognostic ERGs that were differentially expressed in HCC patients. Then, using least absolute shrinkage and selection operator (LASSO) regression analysis, a six-gene signature was constructed, and patients were divided into high- and low-risk groups. Validation was performed on HCC patients from the ICGC database. Patients in the high-risk group had a significantly lower chance of survival than those in the low-risk group (p < 0.001 in both databases). The predictive ability of the signature was determined by the receiver operating characteristic (ROC) curve. The risk score was then shown to be an independent prognostic factor for the overall survival (OS) of HCC patients based on the results of univariate and multivariate analyses. We also created a practical nomogram combining the prognostic model with other clinical features. Moreover, functional enrichment analysis revealed that these genes are linked to tumor immunity. In conclusion, our findings showed that a novel six-gene signature related to epigenetics can accurately predict the occurrence and prognosis of HCC.
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Chen D, Zhao Z, Chen L, Li Q, Zou J, Liu S. PPM1G promotes the progression of hepatocellular carcinoma via phosphorylation regulation of alternative splicing protein SRSF3. Cell Death Dis 2021; 12:722. [PMID: 34290239 PMCID: PMC8295330 DOI: 10.1038/s41419-021-04013-y] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Revised: 07/06/2021] [Accepted: 07/07/2021] [Indexed: 12/14/2022]
Abstract
Emerging evidence has demonstrated that alternative splicing has a vital role in regulating protein function, but how alternative splicing factors can be regulated remains unclear. We showed that the PPM1G, a protein phosphatase, regulated the phosphorylation of SRSF3 in hepatocellular carcinoma (HCC) and contributed to the proliferation, invasion, and metastasis of HCC. PPM1G was highly expressed in HCC tissues compared to adjacent normal tissues, and higher levels of PPM1G were observed in adverse staged HCCs. The higher levels of PPM1G were highly correlated with poor prognosis, which was further validated in the TCGA cohort. The knockdown of PPM1G inhibited the cell growth and invasion of HCC cell lines. Further studies showed that the knockdown of PPM1G inhibited tumor growth in vivo. The mechanistic analysis showed that the PPM1G interacted with proteins related to alternative splicing, including SRSF3. Overexpression of PPM1G promoted the dephosphorylation of SRSF3 and changed the alternative splicing patterns of genes related to the cell cycle, the transcriptional regulation in HCC cells. In addition, we also demonstrated that the promoter of PPM1G was activated by multiple transcription factors and co-activators, including MYC/MAX and EP300, MED1, and ELF1. Our study highlighted the essential role of PPM1G in HCC and shed new light on unveiling the regulation of alternative splicing in malignant transformation.
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Affiliation(s)
- Dawei Chen
- Department of Hepatopancreatobiliary Surgery, Jiangyin People's Hospital, School of Medicine, Southeast University, No. 163, Shoushan Road, Jiangyin, 214400, Jiangsu Province, China
| | - Zhenguo Zhao
- Department of Hepatopancreatobiliary Surgery, Jiangyin People's Hospital, School of Medicine, Southeast University, No. 163, Shoushan Road, Jiangyin, 214400, Jiangsu Province, China
| | - Lu Chen
- Department of Hepatopancreatobiliary Surgery, Jiangyin People's Hospital, School of Medicine, Southeast University, No. 163, Shoushan Road, Jiangyin, 214400, Jiangsu Province, China
| | - Qinghua Li
- Department of Hepatopancreatobiliary Surgery, Jiangyin People's Hospital, School of Medicine, Southeast University, No. 163, Shoushan Road, Jiangyin, 214400, Jiangsu Province, China
| | - Jixue Zou
- Liver Cancer Institute, Zhongshan Hospital, Fudan University, No. 180, Fenglin Road, Shanghai, 200032, China.
| | - Shuanghai Liu
- Department of Hepatopancreatobiliary Surgery, Jiangyin People's Hospital, School of Medicine, Southeast University, No. 163, Shoushan Road, Jiangyin, 214400, Jiangsu Province, China.
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PPM1F in hippocampal dentate gyrus regulates the depression-related behaviors by modulating neuronal excitability. Exp Neurol 2021; 340:113657. [PMID: 33639208 DOI: 10.1016/j.expneurol.2021.113657] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Revised: 12/28/2020] [Accepted: 02/21/2021] [Indexed: 01/21/2023]
Abstract
Major depressive disorder (MDD) is a common, serious, debilitating mental illness. Protein phosphatase Mg2+/Mn2+-dependent 1F (PPM1F), a serine/threonine phosphatase, has been reported to have multiple biological and cellular functions. However, the effects of PPM1F and its neuronal substrates on depressive behaviors remain largely unknown. Here, we showed that PPM1F is widely distributed in the hippocampus, and chronic unpredictable stress (CUS) can induce increased expression of PPM1F in the hippocampus, which was correlated with depression-associated behaviors. Overexpression of PPM1F mediated by adeno-associated virus (AAV) in the dentate gyrus (DG) produced depression-related behaviors and enhanced susceptibility to subthreshold CUS (SCUS) in both male and female mice, while, knockout of PPM1F in DG produced antidepressant phonotypes under stress conditions. Whole-cell patch-clamp recordings demonstrated that overexpression of PPM1F increased the neuronal excitability of the granule cells in the DG. Consistent with neuronal hyperexcitability, overexpression of PPM1F regulated the expression of certain ion channel genes and induced decreased phosphorylation of Ca2+/calmodulin-dependent protein kinase II (CAMKII) and Adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK) in hippocampus. These results suggest that PPM1F in the DG regulates depression-related behaviors by modulating neuronal excitability, which might be an important pathological gene for depression or other mental diseases.
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10
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Xu Z, Wei J, Qin F, Sun Y, Xiang W, Yuan L, Qin J, Deng K, Zheng T, Li S. Hypoxia-associated alternative splicing signature in lung adenocarcinoma. Epigenomics 2020; 13:47-63. [PMID: 33336585 DOI: 10.2217/epi-2020-0399] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Aim: To establish a signature based on hypoxia-related alternative splicing (AS) events for lung adenocarcinoma. Materials & methods: The least absolute shrinkage and selection operator Cox approach was used to construct a prognostic model. A nomogram that integrates the final AS predictor and stage was created. The network of the key AS events and splicing factors was created. Results: We created a prognostic signature of 11 AS events. Moreover, a nomogram that constitutes the pathological stage and risk was exhibited to be greatly effective in estimating the survival likelihood of lung adenocarcinoma patients. Conclusion: Herein we developed the first-ever signature based on hypoxia-related AS events with both prognostic predictive power and diagnostic efficacy.
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Affiliation(s)
- Zhanyu Xu
- Department of Thoracic & Cardiovascular Surgery, The First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi Zhuang Autonomous Region, 530021, PR China
| | - Jiangbo Wei
- Department of Thoracic & Cardiovascular Surgery, The First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi Zhuang Autonomous Region, 530021, PR China
| | - Fanglu Qin
- Guangxi Medical University, Nanning, Guangxi Zhuang Autonomous Region, 530021, PR China
| | - Yu Sun
- Department of Thoracic & Cardiovascular Surgery, The First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi Zhuang Autonomous Region, 530021, PR China
| | - Weiwei Xiang
- Department of Thoracic & Cardiovascular Surgery, The First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi Zhuang Autonomous Region, 530021, PR China
| | - Liqiang Yuan
- Department of Thoracic & Cardiovascular Surgery, The First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi Zhuang Autonomous Region, 530021, PR China
| | - Junqi Qin
- Department of Thoracic & Cardiovascular Surgery, The First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi Zhuang Autonomous Region, 530021, PR China
| | - Kun Deng
- Department of Thoracic & Cardiovascular Surgery, The First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi Zhuang Autonomous Region, 530021, PR China
| | - Tiaozhan Zheng
- Department of Thoracic & Cardiovascular Surgery, The First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi Zhuang Autonomous Region, 530021, PR China
| | - Shikang Li
- Department of Thoracic & Cardiovascular Surgery, The First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi Zhuang Autonomous Region, 530021, PR China
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11
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Yu K, Tian H, Deng H. PPM1G restricts innate immune signaling mediated by STING and MAVS and is hijacked by KSHV for immune evasion. SCIENCE ADVANCES 2020; 6:6/47/eabd0276. [PMID: 33219031 PMCID: PMC7679160 DOI: 10.1126/sciadv.abd0276] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Accepted: 10/07/2020] [Indexed: 05/10/2023]
Abstract
The adaptor proteins, STING and MAVS, are components of critical pathogen-sensing pathways that induce innate immunity. Phosphorylation of either adaptor results in activation of the type I interferon pathway. How this phosphorylation is regulated and how it is manipulated by pathogens remain largely unknown. Here, we identified host protein phosphatase, Mg2+/Mn2+ dependent 1G (PPM1G) as a negative regulator of innate immune pathways and showed that this host system is hijacked by Kaposi's sarcoma-associated herpesvirus (KSHV). Mechanistically, KSHV tegument protein ORF33 interacts with STING/MAVS and enhances recruitment of PPM1G to dephosphorylate p-STING/p-MAVS for immunosuppression. Inhibition of PPM1G expression improves the antiviral response against both DNA and RNA viruses. Collectively, our study shows that PPM1G restricts both cytosolic DNA- and RNA-sensing pathways to naturally balance the intensity of the antiviral response. Manipulation of PPM1G by KSHV provides an important strategy for immune evasion.
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Affiliation(s)
- Kuai Yu
- CAS Key Laboratory of Infection and Immunity, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Huabin Tian
- CAS Key Laboratory of Infection and Immunity, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Hongyu Deng
- CAS Key Laboratory of Infection and Immunity, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.
- University of Chinese Academy of Sciences, Beijing 100049, China
- CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
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12
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Cellular Identification and In Silico Characterization of Protein Phosphatase 2C (PP2C) of Cryptosporidium parvum. Acta Parasitol 2020; 65:704-715. [PMID: 32347536 DOI: 10.2478/s11686-020-00209-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Accepted: 03/25/2020] [Indexed: 12/18/2022]
Abstract
PURPOSE Cryptosporidium parvum is an Apicomplexa parasite that causes watery diarrhea (cryptosporidiosis), especially in children and immunocompromised adults (the latter in a very severe form). No effective treatment exists against infection by this parasite. Phosphatases participate in the regulation of various cellular functions and are thus considered potential therapeutic targets in many diseases. The aim of the present study was to indirectly identify and in silico characterize a protein phosphatase 2C of C. parvum. METHODS Western blot and indirect immunofluorescence microscopy were performed with a polyclonal antibody against Leishmania major PP2C. Possible cross-reactivity with LmPP2C was assessed by in silico sequence homology to analyze phylogenetic relationships between distinct C. parvum PP2Cs. In addition, another bioinformatics approach was used to predict the possible relationship and function of C. parvum PP2C in the regulation of several cellular processes. RESULTS Western blotting showed a protein of approximately 72 kDa. With immunofluorescence, PP2C was localized in the nucleus of oocysts (with some additional labeling in the cytoplasm) and at the apical region of sporozoites. By aligning C. parvum PP2C with known ortholog sequences and carrying out PPI analysis, a determination could be made of the degree of conservation of these enzymes, their possible relationship, and their function in the regulation of several cellular processes associated with a likely nuclear location. CONCLUSION Microscopic localization by immunofluorescence identified CpPP2C at the nucleus in oocysts and at the apical end of the sporozoite body. Hence, this enzyme could be associated with proteins that have an important role in the regulation of transcription and other processes orchestrated by MAPK kinases, according to in silico analysis.
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13
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Metal-dependent Ser/Thr protein phosphatase PPM family: Evolution, structures, diseases and inhibitors. Pharmacol Ther 2020; 215:107622. [PMID: 32650009 DOI: 10.1016/j.pharmthera.2020.107622] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Accepted: 06/29/2020] [Indexed: 02/06/2023]
Abstract
Protein phosphatases and kinases control multiple cellular events including proliferation, differentiation, and stress responses through regulating reversible protein phosphorylation, the most important post-translational modification. Members of metal-dependent protein phosphatase (PPM) family, also known as PP2C phosphatases, are Ser/Thr phosphatases that bind manganese/magnesium ions (Mn2+/Mg2+) in their active center and function as single subunit enzymes. In mammals, there are 20 isoforms of PPM phosphatases: PPM1A, PPM1B, PPM1D, PPM1E, PPM1F, PPM1G, PPM1H, PPM1J, PPM1K, PPM1L, PPM1M, PPM1N, ILKAP, PDP1, PDP2, PHLPP1, PHLPP2, PP2D1, PPTC7, and TAB1, whereas there are only 8 in yeast. Phylogenetic analysis of the DNA sequences of vertebrate PPM isoforms revealed that they can be divided into 12 different classes: PPM1A/PPM1B/PPM1N, PPM1D, PPM1E/PPM1F, PPM1G, PPM1H/PPM1J/PPM1M, PPM1K, PPM1L, ILKAP, PDP1/PDP2, PP2D1/PHLPP1/PHLPP2, TAB1, and PPTC7. PPM-family members have a conserved catalytic core region, which contains the metal-chelating residues. The different isoforms also have isoform specific regions within their catalytic core domain and terminal domains, and these regions may be involved in substrate recognition and/or functional regulation of the phosphatases. The twenty mammalian PPM phosphatases are involved in regulating diverse cellular functions, such as cell cycle control, cell differentiation, immune responses, and cell metabolism. Mutation, overexpression, or deletion of the PPM phosphatase gene results in abnormal cellular responses, which lead to various human diseases. This review focuses on the structures and biological functions of the PPM-phosphatase family and their associated diseases. The development of specific inhibitors against the PPM phosphatase family as a therapeutic strategy will also be discussed.
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Kumar P, Tathe P, Chaudhary N, Maddika S. PPM1G forms a PPP-type phosphatase holoenzyme with B56δ that maintains adherens junction integrity. EMBO Rep 2019; 20:e46965. [PMID: 31432583 PMCID: PMC6776900 DOI: 10.15252/embr.201846965] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2018] [Revised: 07/26/2019] [Accepted: 08/02/2019] [Indexed: 12/11/2022] Open
Abstract
Serine/threonine phosphatases achieve substrate diversity by forming distinct holoenzyme complexes in cells. Although the PPP family of serine/threonine phosphatase family members such as PP1 and PP2A are well known to assemble and function as holoenzymes, none of the PPM family members were so far shown to act as holoenzymes. Here, we provide evidence that PPM1G, a member of PPM family of serine/threonine phosphatases, forms a distinct holoenzyme complex with the PP2A regulatory subunit B56δ. B56δ promotes the re-localization of PPM1G to the cytoplasm where the phosphatase can access a discrete set of substrates. Further, we unveil α-catenin, a component of adherens junction, as a new substrate for the PPM1G-B56 phosphatase complex in the cytoplasm. B56δ-PPM1G dephosphorylates α-catenin at serine 641, which is necessary for the appropriate assembly of adherens junctions and the prevention of aberrant cell migration. Collectively, we reveal a new holoenzyme with PPM1G-B56δ as integral components, in which the regulatory subunit provides accessibility to distinct substrates for the phosphatase by defining its cellular localization.
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Affiliation(s)
- Parveen Kumar
- Laboratory of Cell Death & Cell SurvivalCentre for DNA Fingerprinting and Diagnostics (CDFD)Uppal, HyderabadIndia
- Graduate StudiesManipal Academy of Higher EducationManipalIndia
| | - Prajakta Tathe
- Laboratory of Cell Death & Cell SurvivalCentre for DNA Fingerprinting and Diagnostics (CDFD)Uppal, HyderabadIndia
- Graduate StudiesManipal Academy of Higher EducationManipalIndia
| | - Neelam Chaudhary
- Laboratory of Cell Death & Cell SurvivalCentre for DNA Fingerprinting and Diagnostics (CDFD)Uppal, HyderabadIndia
| | - Subbareddy Maddika
- Laboratory of Cell Death & Cell SurvivalCentre for DNA Fingerprinting and Diagnostics (CDFD)Uppal, HyderabadIndia
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15
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Georges A, Marcon E, Greenblatt J, Frappier L. Identification and Characterization of USP7 Targets in Cancer Cells. Sci Rep 2018; 8:15833. [PMID: 30367141 PMCID: PMC6203733 DOI: 10.1038/s41598-018-34197-x] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Accepted: 10/12/2018] [Indexed: 02/07/2023] Open
Abstract
The ubiquitin specific protease, USP7, regulates multiple cellular pathways relevant for cancer through its ability to bind and sometimes stabilize specific target proteins through deubiquitylation. To gain a more complete profile of USP7 interactions in cancer cells, we performed affinity purification coupled to mass spectrometry to identify USP7 binding targets in gastric carcinoma cells. This confirmed reported associations of USP7 with USP11, PPM1G phosphatase and TRIP12 E3 ubiquitin ligase as well as identifying novel interactions with two DEAD/DEAH-box RNA helicases, DDX24 and DHX40. Using USP7 binding pocket mutants, we show that USP11, PPM1G, TRIP12 and DDX24 bind USP7 through its TRAF domain binding pocket, while DHX40 interacts with USP7 through a distinct binding pocket in the Ubl2 domain. P/A/ExxS motifs in USP11 and DDX24 that are critical for USP7 binding were also identified. Modulation of USP7 expression levels and inhibition of USP7 catalytic activity in multiple cells lines showed that USP7 consistently stabilizes DDX24, DHX40 and TRIP12 dependent on its catalytic activity, while USP11 and PPM1G levels were not consistently affected. Our study better defines the mechanisms of USP7 interaction with known targets and identifies DDX24 and DHX40 as new targets that are specifically bound and regulated by USP7.
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Affiliation(s)
- Anna Georges
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Edyta Marcon
- Donnelly Centre, University of Toronto, Toronto, Canada
| | - Jack Greenblatt
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada.,Donnelly Centre, University of Toronto, Toronto, Canada
| | - Lori Frappier
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada.
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Kolupaeva V. Serine-threonine protein phosphatases: Lost in translation. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2018; 1866:83-89. [PMID: 30401537 DOI: 10.1016/j.bbamcr.2018.08.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Revised: 07/26/2018] [Accepted: 08/08/2018] [Indexed: 12/17/2022]
Abstract
Protein synthesis is one of the most complex and energy-consuming processes in eukaryotic cells and therefore is tightly regulated. One of the main mechanisms of translational control is post-translational modifications of the components of translational apparatus. Phosphorylation status of translation factors depends on the balanced action of kinases and phosphatases. While many kinase-dependent events are well defined, phosphatases that counteract phosphorylation are rarely determined. This mini-review focuses on the regulation of activity of translational initiation factors by serine/threonine phosphatases.
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Affiliation(s)
- Victoria Kolupaeva
- NYU College of Dentistry, Department of Basic Science and Craniofacial Biology, 345 E 24th St, New York, NY 10010, United States of America.
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17
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Pyo J, Ryu J, Kim W, Choi JS, Jeong JW, Kim JE. The Protein Phosphatase PPM1G Destabilizes HIF-1α Expression. Int J Mol Sci 2018; 19:ijms19082297. [PMID: 30081604 PMCID: PMC6121667 DOI: 10.3390/ijms19082297] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Revised: 07/23/2018] [Accepted: 08/01/2018] [Indexed: 12/30/2022] Open
Abstract
Hypoxia-inducible factors (HIFs) are key regulators of hypoxic responses, and their stability and transcriptional activity are controlled by several kinases. However, the regulation of HIF by protein phosphatases has not been thoroughly investigated. Here, we found that overexpression of Mg2+/Mn2+-dependent protein phosphatase 1 gamma (PPM1G), one of Ser/Thr protein phosphatases, downregulated protein expression of ectopic HIF-1α under normoxic or acute hypoxic conditions. In addition, the deficiency of PPM1G upregulated protein expression of endogenous HIF-1α under normoxic or acute oxidative stress conditions. PPM1G decreased expression of HIF-1α via the proteasomal pathway. PPM1G-mediated HIF-1α degradation was dependent on prolyl hydroxylase (PHD), but independent of von Hippel-Lindau (VHL). These data suggest that PPM1G is critical for the control of HIF-1α-dependent responses.
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Affiliation(s)
- Jaehyuk Pyo
- Department of Biomedical Science, Graduate School, Kyung Hee University, Seoul 02447, Korea.
| | - Jaewook Ryu
- Department of Biomedical Science, Graduate School, Kyung Hee University, Seoul 02447, Korea.
| | - Wootae Kim
- Department of Biomedical Science, Graduate School, Kyung Hee University, Seoul 02447, Korea.
| | - Jae-Sun Choi
- Department of Biomedical Science, Graduate School, Kyung Hee University, Seoul 02447, Korea.
| | - Joo-Won Jeong
- Department of Biomedical Science, Graduate School, Kyung Hee University, Seoul 02447, Korea.
- Department of Anatomy and Neurobiology, School of Medicine, Kyung Hee University, Seoul 02447, Korea.
| | - Ja-Eun Kim
- Department of Biomedical Science, Graduate School, Kyung Hee University, Seoul 02447, Korea.
- Department of Pharmacology, School of Medicine, Kyung Hee University, Seoul 02447, Korea.
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18
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Narla G, Sangodkar J, Ryder CB. The impact of phosphatases on proliferative and survival signaling in cancer. Cell Mol Life Sci 2018; 75:2695-2718. [PMID: 29725697 PMCID: PMC6023766 DOI: 10.1007/s00018-018-2826-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2017] [Revised: 03/24/2018] [Accepted: 04/23/2018] [Indexed: 02/06/2023]
Abstract
The dynamic and stringent coordination of kinase and phosphatase activity controls a myriad of physiologic processes. Aberrations that disrupt the balance of this interplay represent the basis of numerous diseases. For a variety of reasons, early work in this area portrayed kinases as the dominant actors in these signaling events with phosphatases playing a secondary role. In oncology, these efforts led to breakthroughs that have dramatically altered the course of certain diseases and directed vast resources toward the development of additional kinase-targeted therapies. Yet, more recent scientific efforts have demonstrated a prominent and sometimes driving role for phosphatases across numerous malignancies. This maturation of the phosphatase field has brought with it the promise of further therapeutic advances in the field of oncology. In this review, we discuss the role of phosphatases in the regulation of cellular proliferation and survival signaling using the examples of the MAPK and PI3K/AKT pathways, c-Myc and the apoptosis machinery. Emphasis is placed on instances where these signaling networks are perturbed by dysregulation of specific phosphatases to favor growth and persistence of human cancer.
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Affiliation(s)
| | - Jaya Sangodkar
- Icahn School of Medicine at Mount Sinai, New York, NY, USA
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19
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Abstract
Translation is a key step in the regulation of gene expression and one of the most energy-consuming processes in the cell. In response to various stimuli, multiple signaling pathways converge on the translational machinery to regulate its function. To date, the roles of phosphoinositide 3-kinase (PI3K)/AKT and the mitogen-activated protein kinase (MAPK) pathways in the regulation of translation are among the best understood. Both pathways engage the mechanistic target of rapamycin (mTOR) to regulate a variety of components of the translational machinery. While these pathways regulate protein synthesis in homeostasis, their dysregulation results in aberrant translation leading to human diseases, including diabetes, neurological disorders, and cancer. Here we review the roles of the PI3K/AKT and MAPK pathways in the regulation of mRNA translation. We also highlight additional signaling mechanisms that have recently emerged as regulators of the translational apparatus.
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20
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Earwaker P, Anderson C, Willenbrock F, Harris AL, Protheroe AS, Macaulay VM. RAPTOR up-regulation contributes to resistance of renal cancer cells to PI3K-mTOR inhibition. PLoS One 2018; 13:e0191890. [PMID: 29389967 PMCID: PMC5794101 DOI: 10.1371/journal.pone.0191890] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Accepted: 01/12/2018] [Indexed: 02/04/2023] Open
Abstract
The outlook for patients with advanced renal cell cancer (RCC) has been improved by targeted agents including inhibitors of the PI3 kinase (PI3K)-AKT-mTOR axis, although treatment resistance is a major problem. Here, we aimed to understand how RCC cells acquire resistance to PI3K-mTOR inhibition. We used the RCC4 cell line to generate a model of in vitro resistance by continuous culture in PI3K-mTOR kinase inhibitor NVP-BEZ235 (BEZ235, Dactolisib). Resistant cells were cross-resistant to mTOR inhibitor AZD2014. Sensitivity was regained after 4 months drug withdrawal, and resistance was partially suppressed by HDAC inhibition, supporting an epigenetic mechanism. BEZ235-resistant cells up-regulated and/or activated numerous proteins including MET, ABL, Notch, IGF-1R, INSR and MEK/ERK. However, resistance was not reversed by inhibiting or depleting these pathways, suggesting that many induced changes were passengers not drivers of resistance. BEZ235 blocked phosphorylation of mTOR targets S6 and 4E-BP1 in parental cells, but 4E-BP1 remained phosphorylated in resistant cells, suggesting BEZ235-refractory mTORC1 activity. Consistent with this, resistant cells over-expressed mTORC1 component RAPTOR at the mRNA and protein level. Furthermore, BEZ235 resistance was suppressed by RAPTOR depletion, or allosteric mTORC1 inhibitor rapamycin. These data reveal that RAPTOR up-regulation contributes to PI3K-mTOR inhibitor resistance, and suggest that RAPTOR expression should be included in the pharmacodynamic assessment of mTOR kinase inhibitor trials.
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Affiliation(s)
| | | | | | - Adrian L. Harris
- Oxford Cancer and Haematology Centre, Oxford University Hospitals NHS Trust, Churchill Hospital, Oxford, United Kingdom
| | - Andrew S. Protheroe
- Oxford Cancer and Haematology Centre, Oxford University Hospitals NHS Trust, Churchill Hospital, Oxford, United Kingdom
| | - Valentine M. Macaulay
- Department of Oncology, Oxford, United Kingdom
- Oxford Cancer and Haematology Centre, Oxford University Hospitals NHS Trust, Churchill Hospital, Oxford, United Kingdom
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21
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Sciuto MR, Warnken U, Schnölzer M, Valvo C, Brunetto L, Boe A, Biffoni M, Krammer PH, De Maria R, Haas TL. Two-Step Coimmunoprecipitation (TIP) Enables Efficient and Highly Selective Isolation of Native Protein Complexes. Mol Cell Proteomics 2017; 17:993-1009. [PMID: 29217617 DOI: 10.1074/mcp.o116.065920] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Revised: 11/22/2017] [Indexed: 11/06/2022] Open
Abstract
Coimmunoprecipitation (co-IP) is one of the most frequently used techniques to study protein-protein (PPIs) or protein-nucleic acid interactions (PNIs). However, the presence of coprecipitated contaminants is a well-recognized issue associated with single-step co-IPs. To overcome this limitation, we developed the two-step co-IP (TIP) strategy that enables sequential coimmunoprecipitations of endogenous protein complexes. TIP can be performed with a broad range of mono- and polyclonal antibodies targeting a single protein or different components of a given complex. TIP results in a highly selective enrichment of protein complexes and thus outperforms single-step co-IPs for downstream applications such as mass spectrometry for the identification of PPIs and quantitative PCR for the analysis of PNIs. We benchmarked TIP for the identification of CD95/FAS-interacting proteins in primary human CD4+ T cells, which recapitulated all major known interactors, but also enabled the proteomics discovery of PPM1G and IPO7 as new interaction partners. For its feasibility and high performance, we propose TIP as an advanced tool for the isolation of highly purified protein-protein and protein-nucleic acid complexes under native expression conditions.
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Affiliation(s)
- Maria Rita Sciuto
- From the ‡Department of Hematology and Oncology, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161, Rome, Italy;
| | - Uwe Warnken
- §Functional Proteome Analysis, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 580, 69120, Heidelberg, Germany
| | - Martina Schnölzer
- §Functional Proteome Analysis, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 580, 69120, Heidelberg, Germany
| | - Cecilia Valvo
- From the ‡Department of Hematology and Oncology, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161, Rome, Italy.,¶Institute of General Pathology, Catholic University and Gemelli Polyclinic, Largo F. Vito 1, 00168, Rome, Italy
| | - Lidia Brunetto
- From the ‡Department of Hematology and Oncology, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161, Rome, Italy
| | - Alessandra Boe
- From the ‡Department of Hematology and Oncology, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161, Rome, Italy
| | - Mauro Biffoni
- From the ‡Department of Hematology and Oncology, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161, Rome, Italy
| | - Peter H Krammer
- ‖Department of Tumor Immunology, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120, Heidelberg, Germany
| | - Ruggero De Maria
- ¶Institute of General Pathology, Catholic University and Gemelli Polyclinic, Largo F. Vito 1, 00168, Rome, Italy
| | - Tobias L Haas
- From the ‡Department of Hematology and Oncology, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161, Rome, Italy; .,¶Institute of General Pathology, Catholic University and Gemelli Polyclinic, Largo F. Vito 1, 00168, Rome, Italy
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22
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Wang L, Arras J, Katsha A, Hamdan S, Belkhiri A, Ecsedy J, El-Rifai W. Cisplatin-resistant cancer cells are sensitive to Aurora kinase A inhibition by alisertib. Mol Oncol 2017; 11:981-995. [PMID: 28417568 PMCID: PMC5537695 DOI: 10.1002/1878-0261.12066] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2017] [Revised: 03/23/2017] [Accepted: 04/09/2017] [Indexed: 12/13/2022] Open
Abstract
De novo and acquired resistance to platinum therapy such as cisplatin (CDDP) is a clinical challenge in gastric cancer treatment. Aberrant expression and activation of aurora kinase A (AURKA) and eukaryotic translation initiation factor 4E (eIF4E) are detected in several cancer types. Herein, we investigated the role of AURKA in CDDP resistance in gastric cancer. Western blot analysis demonstrated overexpression of AURKA and phosphorylation of eIF4E in acquired and de novo CDDP‐resistant gastric cancer models. Inhibition of AURKA with MLN8237 (alisertib) alone or in combination with CDDP significantly suppressed viability of CDDP‐resistant cancer cells (P < 0.01). Additionally, inhibition or knockdown of AURKA decreased protein expression of p‐eIF4E (S209), HDM2, and c‐MYC in CDDP‐resistant cell models. This was associated with a significant decrease in cap‐dependent translation levels (P < 0.01). In vivo tumor xenografts data corroborated these results and confirmed that inhibition of AURKA was sufficient to overcome CDDP resistance in gastric cancer. Our data demonstrate that AURKA promotes acquired and de novo resistance to CDDP through regulation of p‐eIF4E (S209), c‐MYC, HDM2, and cap‐dependent translation. Targeting AURKA could be an effective therapeutic approach to overcome CDDP resistance in refractory gastric cancer and possibly other cancer types.
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Affiliation(s)
- Lihong Wang
- Department of Surgery and Cancer Biology, Vanderbilt University Medical Center, Nashville, TN, USA.,Department of Veterans Affairs, Tennessee Valley Healthcare System, Nashville, TN, USA
| | - Janet Arras
- Department of Surgery and Cancer Biology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Ahmed Katsha
- Department of Surgery and Cancer Biology, Vanderbilt University Medical Center, Nashville, TN, USA.,Science and Engineering Department, Raritan Valley Community College, Branchburg, NJ, USA
| | - Saif Hamdan
- Department of Surgery and Cancer Biology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Abbes Belkhiri
- Department of Surgery and Cancer Biology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Jeffrey Ecsedy
- Translational Medicine, Millennium Pharmaceuticals, Inc., Cambridge, MA, USA a wholly owned subsidiary of Takeda Pharmaceutical Company Limited
| | - Wael El-Rifai
- Department of Surgery and Cancer Biology, Vanderbilt University Medical Center, Nashville, TN, USA.,Department of Veterans Affairs, Tennessee Valley Healthcare System, Nashville, TN, USA
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23
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Katsha A, Wang L, Arras J, Omar OM, Ecsedy J, Belkhiri A, El-Rifai W. Activation of EIF4E by Aurora Kinase A Depicts a Novel Druggable Axis in Everolimus-Resistant Cancer Cells. Clin Cancer Res 2017; 23:3756-3768. [PMID: 28073841 DOI: 10.1158/1078-0432.ccr-16-2141] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Revised: 12/29/2016] [Accepted: 12/29/2016] [Indexed: 01/11/2023]
Abstract
Purpose: Aurora kinase A (AURKA) is overexpressed in several cancer types, making it an attractive druggable target in clinical trials. In this study, we investigated the role of AURKA in regulating EIF4E, cap-dependent translation, and resistance to mTOR inhibitor, RAD001 (everolimus).Experimental Design: Tumor xenografts and in vitro cell models of upper gastrointestinal adenocarcinomas (UGC) were used to determine the role of AURKA in the activation of EIF4E and cap-dependent translation. Overexpression, knockdown, and pharmacologic inhibition of AURKA were used in vitro and in vivoResults: Using in vitro cell models, we found that high protein levels of AURKA mediate phosphorylation of EIF4E and upregulation of c-MYC. Notably, we detected overexpression of endogenous AURKA in everolimus-resistant UGC cell models. AURKA mediated phosphorylation of EIF4E, activation of cap-dependent translation, and an increase in c-MYC protein levels. Targeting AURKA using genetic knockdown or a small-molecule inhibitor, alisertib, reversed these molecular events, leading to a decrease in cancer cell survival in acquired and intrinsic resistant cell models. Mechanistic studies demonstrated that AURKA binds to and inactivates protein phosphatase 2A, a negative regulator of EIF4E, leading to phosphorylation and activation of EIF4E in an AKT-, ERK1/2-, and mTOR-independent manner. Data from tumor xenograft mouse models confirmed that everolimus-resistant cancer cells are sensitive to alisertib.Conclusions: Our results indicate that AURKA plays an important role in the activation of EIF4E and cap-dependent translation. Targeting the AURKA-EIF4E-c-MYC axis using alisertib is a novel therapeutic strategy that can be applicable for everolimus-resistant tumors and/or subgroups of cancers that show overexpression of AURKA and activation of EIF4E and c-MYC. Clin Cancer Res; 23(14); 3756-68. ©2017 AACR.
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Affiliation(s)
- Ahmed Katsha
- Department of Surgery, Vanderbilt University Medical Center, Nashville, Tennessee.,Department of Science and Engineering, Raritan Valley Community College, Branchburg, New Jersey
| | - Lihong Wang
- Department of Surgery, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Janet Arras
- Department of Surgery, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Omar M Omar
- Department of Surgery, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Jeffrey Ecsedy
- Translational Medicine, Millennium Pharmaceuticals, Inc., Cambridge, Massachusetts, a wholly owned subsidiary of Takeda Pharmaceutical Company Limited
| | - Abbes Belkhiri
- Department of Surgery, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Wael El-Rifai
- Department of Surgery, Vanderbilt University Medical Center, Nashville, Tennessee. .,Department of Cancer Biology, Vanderbilt University Medical Center, Nashville, Tennessee.,Department of Veterans Affairs, Tennessee Valley Healthcare System, Nashville, Tennessee
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24
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mTORC1 signalling and eIF4E/4E-BP1 translation initiation factor stoichiometry influence recombinant protein productivity from GS-CHOK1 cells. Biochem J 2016; 473:4651-4664. [PMID: 27760840 PMCID: PMC5147049 DOI: 10.1042/bcj20160845] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2016] [Revised: 10/17/2016] [Accepted: 10/19/2016] [Indexed: 12/14/2022]
Abstract
Many protein-based biotherapeutics are produced in cultured Chinese hamster ovary (CHO) cell lines. Recent reports have demonstrated that translation of recombinant mRNAs and global control of the translation machinery via mammalian target of rapamycin (mTOR) signalling are important determinants of the amount and quality of recombinant protein such cells can produce. mTOR complex 1 (mTORC1) is a master regulator of cell growth/division, ribosome biogenesis and protein synthesis, but the relationship between mTORC1 signalling, cell growth and proliferation and recombinant protein yields from mammalian cells, and whether this master regulating signalling pathway can be manipulated to enhance cell biomass and recombinant protein production (rPP) are not well explored. We have investigated mTORC1 signalling and activity throughout batch culture of a panel of sister recombinant glutamine synthetase-CHO cell lines expressing different amounts of a model monoclonal IgG4, to evaluate the links between mTORC1 signalling and cell proliferation, autophagy, recombinant protein expression, global protein synthesis and mRNA translation initiation. We find that the expression of the mTORC1 substrate 4E-binding protein 1 (4E-BP1) fluctuates throughout the course of cell culture and, as expected, that the 4E-BP1 phosphorylation profiles change across the culture. Importantly, we find that the eIF4E/4E-BP1 stoichiometry positively correlates with cell productivity. Furthermore, eIF4E amounts appear to be co-regulated with 4E-BP1 amounts. This may reflect a sensing of either change at the mRNA level as opposed to the protein level or the fact that the phosphorylation status, as well as the amount of 4E-BP1 present, is important in the co-regulation of eIF4E and 4E-BP1.
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25
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Sun C, Wang G, Wrighton KH, Lin H, Songyang Z, Feng XH, Lin X. Regulation of p27 Kip1 phosphorylation and G1 cell cycle progression by protein phosphatase PPM1G. Am J Cancer Res 2016; 6:2207-2220. [PMID: 27822412 PMCID: PMC5088286] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2016] [Accepted: 05/11/2016] [Indexed: 06/06/2023] Open
Abstract
The cell cycle, an essential process leading to the cell division, is stringently controlled by the key cell cycle regulators, cyclin-CDK complexes, whose activity is further regulated by a variety of mechanisms. p27Kip1 is a cyclin-CDK inhibitor that arrests the cell cycle at the G1 phase by blocking the activation of cyclin E-CDK2 complex, preventing the improper entry to the cell cycle. Dysfunction of p27 has been frequently observed in many types of human cancers, resulting from p27 protein degradation and cytoplasmic mislocalization, which are highly regulated by the phosphorylation status of p27. Although the kinases that phosphorylate p27 have been extensively studied, phosphatases that dephosphorylate p27 remain to be elucidated. By using genomic phosphatase screening, we identified a PPM family phosphatase, PPM1G, which could reduce p27 phosphorylation at T198. We further confirmed that PPM1G is a novel p27 phosphatase by demonstrating that PPM1G can interact with and dephosphorylate p27 in cells and in vitro. Functionally, ectopic expression of PPM1G enhanced p27 protein stability and delayed cell cycle progression from G1 to S phase. In accordance, knockdown of PPM1G accelerated p27 degradation during G1 phase and rendered cells resistant to the cell cycle arrest induced by serum deprivation. Mechanistically, PPM1G inhibited the interaction of p27 to 14-3-3θ, a chaperone protein that facilitates p27 nuclear export. Knockdown of PPM1G promoted the cytoplasmic localization of p27. Taken together, our studies identified PPM1G as a novel regulator of p27 that dephosphorylates p27 at T198 site and, together with p27 kinases, PPM1G controls cell cycle progression by maintaining the proper level of p27 protein.
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Affiliation(s)
- Chuang Sun
- Department of Molecular Physiology and Biophysics, Baylor College of MedicineHouston, TX 77030, USA
- Michael E. DeBakey Department of Surgery, Baylor College of MedicineHouston, TX 77030, USA
| | - Gaohang Wang
- Michael E. DeBakey Department of Surgery, Baylor College of MedicineHouston, TX 77030, USA
- Department of Molecular & Cellular Biology, Baylor College of MedicineHouston, TX 77030, USA
- Life Sciences Institute and Innovation Center for Cell Signaling, Zhejiang UniversityHangzhou, Zhejiang 310058, China
| | - Katharine H Wrighton
- Michael E. DeBakey Department of Surgery, Baylor College of MedicineHouston, TX 77030, USA
- Department of Molecular & Cellular Biology, Baylor College of MedicineHouston, TX 77030, USA
- Present address: Nature Reviews JournalsPorters South, 4 Crinan Street, London, N1 9XW, United Kingdom
| | - Han Lin
- Department of Molecular Physiology and Biophysics, Baylor College of MedicineHouston, TX 77030, USA
| | - Zhou Songyang
- Department of Biochemistry and Molecular Biology, Baylor College of MedicineHouston, TX 77030, USA
| | - Xin-Hua Feng
- Department of Molecular Physiology and Biophysics, Baylor College of MedicineHouston, TX 77030, USA
- Michael E. DeBakey Department of Surgery, Baylor College of MedicineHouston, TX 77030, USA
- Department of Molecular & Cellular Biology, Baylor College of MedicineHouston, TX 77030, USA
- Life Sciences Institute and Innovation Center for Cell Signaling, Zhejiang UniversityHangzhou, Zhejiang 310058, China
| | - Xia Lin
- Michael E. DeBakey Department of Surgery, Baylor College of MedicineHouston, TX 77030, USA
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26
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Cell type-specific control of protein synthesis and proliferation by FGF-dependent signaling to the translation repressor 4E-BP. Proc Natl Acad Sci U S A 2016; 113:7545-50. [PMID: 27313212 DOI: 10.1073/pnas.1605451113] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Regulation of protein synthesis plays a vital role in posttranscriptional modulation of gene expression. Translational control most commonly targets the initiation of protein synthesis: loading 40S ribosome complexes onto mRNA and AUG start codon recognition. This step is initiated by eukaryotic initiation factor 4E (eIF4E) (the m7GTP cap-binding protein), whose binding to eIF4G (a scaffolding subunit) and eIF4A (an ATP-dependent RNA helicase) leads to assembly of active eIF4F complex. The ability of eIF4E to recognize the cap is prevented by its binding to eIF4E binding protein (4E-BP), which thereby inhibits cap-dependent translation by sequestering eIF4E. The 4E-BP activity is, in turn, inhibited by mTORC1 [mTOR (the mechanistic target of rapamycin) complex 1] mediated phosphorylation. Here, we define a previously unidentified mechanism of mTOR-independent 4E-BP1 regulation that is used by chondrocytes upon FGF signaling. Chondrocytes are responsible for the formation of the skeleton long bones. Unlike the majority of cell types where FGF signaling triggers proliferation, chondrocytes respond to FGF with inhibition. We establish that FGF specifically suppresses protein synthesis in chondrocytes, but not in any other cells of mesenchymal origin. Furthermore, 4E-BP1 repressor activity is necessary not only for suppression of protein synthesis, but also for FGF-induced cell-cycle arrest. Importantly, FGF-induced changes in the 4E-BP1 activity observed in cell culture are likewise detected in vivo and reflect the action of FGF signaling on downstream targets during bone development. Thus, our findings demonstrate that FGF signaling differentially impacts protein synthesis through either stimulation or repression, in a cell-type-dependent manner, with 4E-BP1 being a key player.
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27
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Shull AY, Noonepalle SK, Awan FT, Liu J, Pei L, Bollag RJ, Salman H, Ding Z, Shi H. RPPA-based protein profiling reveals eIF4G overexpression and 4E-BP1 serine 65 phosphorylation as molecular events that correspond with a pro-survival phenotype in chronic lymphocytic leukemia. Oncotarget 2016; 6:14632-45. [PMID: 25999352 PMCID: PMC4546493 DOI: 10.18632/oncotarget.4104] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2015] [Accepted: 04/08/2015] [Indexed: 12/22/2022] Open
Abstract
Chronic lymphocytic leukemia (CLL), the most common adult leukemia, remains incurable despite advancements in treatment regimens over the past decade. Several expression profile studies have been pursued to better understand CLL pathogenesis. However, these large-scale studies only provide information at the transcriptional level. To better comprehend the differential protein changes that take place in CLL, we performed a reverse-phase protein array (RPPA) analysis using 167 different antibodies on B-cell lysates from 18 CLL patients and 6 normal donors. From our analysis, we discovered an enrichment of protein alterations involved with mRNA translation, specifically upregulation of the translation initiator eIF4G and phosphorylation of the cap-dependent translation inhibitor 4E-BP1 at serine 65. Interestingly, 4E-BP1 phosphorylation occurred independently of AKT phosphorylation, suggesting a disconnect between PI3K/AKT pathway activation and 4E-BP1 phosphorylation. Based on these results, we treated primary CLL samples with NVP-BEZ235, a PI3K/mTOR dual inhibitor, and compared its apoptotic-inducing potential against the BTK inhibitor Ibrutinib and the PI3Kδ inhibitor Idelalisib. We demonstrated that treatment with NVP-BEZ235 caused greater apoptosis, greater apoptotic cleavage of eIF4G, and greater dephosphorylation of 4E-BP1 in primary CLL cells. Taken together, these results highlight the potential dependence of eIF4G overexpression and 4E-BP1 phosphorylation in CLL survival.
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Affiliation(s)
- Austin Y Shull
- Department of Biochemistry & Molecular Biology, Georgia Regents University, Augusta, Georgia, USA.,GRU Cancer Center, Georgia Regents University, Augusta, Georgia, USA
| | - Satish K Noonepalle
- Department of Biochemistry & Molecular Biology, Georgia Regents University, Augusta, Georgia, USA.,GRU Cancer Center, Georgia Regents University, Augusta, Georgia, USA
| | - Farrukh T Awan
- The Ohio State Comprehensive Cancer Center, The Ohio State University, Columbus, Ohio, USA
| | - Jimei Liu
- GRU Cancer Center, Georgia Regents University, Augusta, Georgia, USA
| | - Lirong Pei
- GRU Cancer Center, Georgia Regents University, Augusta, Georgia, USA
| | - Roni J Bollag
- GRU Cancer Center, Georgia Regents University, Augusta, Georgia, USA.,Department of Pathology, Georgia Regents University, Augusta, Georgia, USA
| | - Huda Salman
- GRU Cancer Center, Georgia Regents University, Augusta, Georgia, USA.,Deparment of Medicine, Georgia Regents University, Augusta, Georgia, USA
| | - Zhiyong Ding
- Department of Systems Biology, University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Huidong Shi
- Department of Biochemistry & Molecular Biology, Georgia Regents University, Augusta, Georgia, USA.,GRU Cancer Center, Georgia Regents University, Augusta, Georgia, USA
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28
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Xu K, Wang L, Feng W, Feng Y, Shu HK. Phosphatidylinositol-3 kinase-dependent translational regulation of Id1 involves the PPM1G phosphatase. Oncogene 2016; 35:5807-5816. [PMID: 27065332 PMCID: PMC5064830 DOI: 10.1038/onc.2016.115] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Revised: 01/04/2016] [Accepted: 01/22/2016] [Indexed: 12/30/2022]
Abstract
Id1 is a helix-loop-helix transcriptional modulator that increases the aggressiveness of malignant glial neoplasms. Since most glioblastomas (GBMs) show increased phosphatidylinositol-3 kinase (PI-3K) signaling, we sought to determine whether this pathway regulates Id1 expression. Higher basal Id1 expression correlates with dysregulated PI-3K signaling in multiple established GBM cell lines. Further characterization of PI-3K-dependent Id1 regulation reveals that chemical or genetic inhibition of PI-3K signaling reduces Id1 protein but not mRNA expression. Overall, PI-3K signaling appears to enhance Id1 translation with no significant effect on its stability. PI-3K signaling is known to regulate protein translation through mTORC1-dependent phosphorylation of 4E-BP1, which reduces its association with and inhibition of the translation initiation factor eIF4E. Interestingly, while inhibition of PI-3K and AKT lowers 4E-BP1 phosphorylation and expression of Id1 in all cases, inhibition of TORC1 with rapamycin does not consistently have a similar effect suggesting an alternative mechanism for PI-3K-dependent regulation of Id1 translation. We now identify a potential role for the serine-threonine phosphatase PPM1G in translational regulation of Id1 protein expression. PPM1G knockdown by siRNA increase both 4E-BP1 phosphorylation and Id1 expression and PPM1G and 4E-BP1 co-associates in GBM cells. Furthermore, PPM1G is a phosphoprotein and this phosphorylation appears to be regulated by PI-3K activity. Finally, PI-3K inhibition increases PPM1G activity when assessed by an in vitro phosphatase assay. Our findings provide the first evidence that the PI-3K/AKT signaling pathway modulates PPM1G activity resulting in a shift in the balance between hyper- and hypo-phosphorylated 4E-BP1 and translational regulation of Id1 expression.
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Affiliation(s)
- K Xu
- Department of Radiation Oncology and the Winship Cancer Institute, Emory University, Atlanta, GA, USA
| | - L Wang
- Department of Radiation Oncology and the Winship Cancer Institute, Emory University, Atlanta, GA, USA
| | - W Feng
- Department of Pharmacology, Emory University, Atlanta, GA, USA
| | - Y Feng
- Department of Pharmacology, Emory University, Atlanta, GA, USA
| | - H-Kg Shu
- Department of Radiation Oncology and the Winship Cancer Institute, Emory University, Atlanta, GA, USA
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29
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Gardner TW, Abcouwer SF, Losiewicz MK, Fort PE. Phosphatase control of 4E-BP1 phosphorylation state is central for glycolytic regulation of retinal protein synthesis. Am J Physiol Endocrinol Metab 2015; 309. [PMID: 26199279 PMCID: PMC4572451 DOI: 10.1152/ajpendo.00180.2015] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Control of protein synthesis in insulin-responsive tissues has been well characterized, but relatively little is known about how this process is regulated in nervous tissues. The retina exhibits a relatively high protein synthesis rate, coinciding with high basal Akt and metabolic activities, with the majority of retinal ATP being derived from aerobic glycolysis. We examined the dependency of retinal protein synthesis on the Akt-mTOR signaling and glycolysis using ex vivo rat retinas. Akt inhibitors significantly reduced retinal protein synthesis but did not affect glycolytic lactate production. Surprisingly, the glycolytic inhibitor 2-deoxyglucose (2-DG) markedly inhibited Akt1 and Akt3 activities, as well as protein synthesis. The effects of 2-DG, and 2-fluorodeoxyglucose (2-FDG) on retinal protein synthesis correlated with inhibition of lactate production and diminished ATP content, with all these effects reversed by provision of d-mannose. 2-DG treatment was not associated with increased AMPK, eEF2, or eIF2α phosphorylation; instead, it caused rapid dephosphorylation of 4E-BP1. 2-DG reduced total mTOR activity by 25%, but surprisingly, it did not reduce mTORC1 activity, as indicated by unaltered raptor-associated mTOR autophosphorylation and ribosomal protein S6 phosphorylation. Dephosphorylation of 4E-BP1 was largely prevented by inhibition of PP1/PP2A phosphatases with okadaic acid and calyculin A, and inhibition of PPM1 phosphatases with cadmium. Thus, inhibition of retinal glycolysis diminished Akt and protein synthesis coinciding with accelerated dephosphorylation of 4E-BP1 independently of mTORC1. These results demonstrate a novel mechanism regulating protein synthesis in the retina involving an mTORC1-independent and phosphatase-dependent regulation of 4E-BP1.
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Affiliation(s)
- Thomas W Gardner
- Kellogg Eye Center, Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, Michigan; and Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan
| | - Steven F Abcouwer
- Kellogg Eye Center, Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, Michigan; and
| | - Mandy K Losiewicz
- Kellogg Eye Center, Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, Michigan; and
| | - Patrice E Fort
- Kellogg Eye Center, Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, Michigan; and
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30
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Rosal-Vela A, García-Rodríguez S, Postigo J, Iglesias M, Longobardo V, Lario A, Merino J, Merino R, Zubiaur M, Sancho J. Distinct serum proteome profiles associated with collagen-induced arthritis and complete Freund's adjuvant-induced inflammation in CD38−/−
mice: The discriminative power of protein species or proteoforms. Proteomics 2015; 15:3382-93. [DOI: 10.1002/pmic.201400536] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2015] [Revised: 04/25/2015] [Accepted: 07/10/2015] [Indexed: 11/06/2022]
Affiliation(s)
- Antonio Rosal-Vela
- Departamento de Biología Celular e Inmunología; Instituto de Parasitología y Biomedicina López Neyra (IPBLN), Consejo Superior de Investigaciones Científicas (CSIC), PTS Granada; Granada Spain
| | - Sonia García-Rodríguez
- Departamento de Biología Celular e Inmunología; Instituto de Parasitología y Biomedicina López Neyra (IPBLN), Consejo Superior de Investigaciones Científicas (CSIC), PTS Granada; Granada Spain
| | - Jorge Postigo
- Departamento de Biología Molecular; Instituto de Formación e Investigación Marqués de Valdecilla, Universidad de Cantabria; Cantabria Spain
| | - Marcos Iglesias
- Departamento de Biología Molecular; Instituto de Formación e Investigación Marqués de Valdecilla, Universidad de Cantabria; Cantabria Spain
| | - Victoria Longobardo
- Unidad de Proteómica; Instituto de Parasitología y Biomedicina López-Neyra (IPBLN), Consejo Superior de Investigaciones Científicas (CSIC), PTS Granada; Granada Spain
| | - Antonio Lario
- Unidad de Proteómica; Instituto de Parasitología y Biomedicina López-Neyra (IPBLN), Consejo Superior de Investigaciones Científicas (CSIC), PTS Granada; Granada Spain
| | - Jesús Merino
- Departamento de Biología Molecular; Instituto de Formación e Investigación Marqués de Valdecilla, Universidad de Cantabria; Cantabria Spain
| | - Ramón Merino
- Instituto de Biomedicina y Biotecnología de Cantabria/CSIC-Universidad de Cantabria-SODERCAN; Cantabria Spain
| | - Mercedes Zubiaur
- Departamento de Biología Celular e Inmunología; Instituto de Parasitología y Biomedicina López Neyra (IPBLN), Consejo Superior de Investigaciones Científicas (CSIC), PTS Granada; Granada Spain
| | - Jaime Sancho
- Departamento de Biología Celular e Inmunología; Instituto de Parasitología y Biomedicina López Neyra (IPBLN), Consejo Superior de Investigaciones Científicas (CSIC), PTS Granada; Granada Spain
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31
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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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