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Choi HH, Zou S, Wu J, Wang H, Phan L, Li K, Zhang P, Chen D, Liu Q, Qin B, Nguyen TAT, Yeung SJ, Fang L, Lee M. EGF Relays Signals to COP1 and Facilitates FOXO4 Degradation to Promote Tumorigenesis. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2020; 7:2000681. [PMID: 33101846 PMCID: PMC7578864 DOI: 10.1002/advs.202000681] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2020] [Revised: 08/19/2020] [Indexed: 05/10/2023]
Abstract
Forkhead-Box Class O 4 (FOXO4) is involved in critical biological functions, but its response to EGF-PKB/Akt signal regulation is not well characterized. Here, it is reported that FOXO4 levels are downregulated in response to EGF treatment, with concurrent elevation of COP9 Signalosome subunit 6 (CSN6) and E3 ubiquitin ligase constitutive photomorphogenic 1 (COP1) levels. Mechanistic studies show that CSN6 binds and regulates FOXO4 stability through enhancing the E3 ligase activity of COP1, and that COP1 directly interacts with FOXO4 through a VP motif on FOXO4 and accelerates the ubiquitin-mediated degradation of FOXO4. Metabolomic studies demonstrate that CSN6 expression leads to serine and glycine production. It is shown that FOXO4 directly binds and suppresses the promoters of serine-glycine-one-carbon (SGOC) pathway genes, thereby diminishing SGOC metabolism. Evidence shows that CSN6 can regulate FOXO4-mediated SGOC gene expression. Thus, these data suggest a link of CSN6-FOXO4 axis and ser/gly metabolism. Further, it is shown that CSN6-COP1-FOXO4 axis is deregulated in cancer and that the protein expression levels of CSN6 and FOXO4 can serve as prognostic markers for cancers. The results illustrate a pathway regulation of FOXO4-mediated serine/glycine metabolism through the function of CSN6-COP1 axis. Insights into this pathway may be strategically designed for therapeutic intervention in cancers.
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Affiliation(s)
- Hyun Ho Choi
- Guangdong Provincial Key Laboratory of Colorectal and Pelvic Floor DiseaseThe Sixth Affiliated HospitalSun Yat‐sen UniversityGuangzhou510655China
- Guangdong Research Institute of GastroenterologyThe Sixth Affiliated HospitalSun Yat‐sen UniversityGuangzhou510655China
| | - Shaomin Zou
- Guangdong Provincial Key Laboratory of Colorectal and Pelvic Floor DiseaseThe Sixth Affiliated HospitalSun Yat‐sen UniversityGuangzhou510655China
- Guangdong Research Institute of GastroenterologyThe Sixth Affiliated HospitalSun Yat‐sen UniversityGuangzhou510655China
| | - Jian‐lin Wu
- State Key Laboratory of Quality Research in Chinese MedicineMacau Institute for Applied Research in Medicine and HealthMacau University of Science and TechnologyMacao999078China
| | - Huashe Wang
- Department of Colorectal SurgeryThe Sixth Affiliated HospitalSun Yat‐sen UniversityGuangzhou510655China
| | - Liem Phan
- Department of Molecular and Cellular OncologyDivision of Basic Science ResearchThe University of Texas MD Anderson Cancer CenterHoustonTX77030USA
| | - Kai Li
- Guangdong Provincial Key Laboratory of Colorectal and Pelvic Floor DiseaseThe Sixth Affiliated HospitalSun Yat‐sen UniversityGuangzhou510655China
- Guangdong Research Institute of GastroenterologyThe Sixth Affiliated HospitalSun Yat‐sen UniversityGuangzhou510655China
| | - Peng Zhang
- Guangdong Provincial Key Laboratory of Colorectal and Pelvic Floor DiseaseThe Sixth Affiliated HospitalSun Yat‐sen UniversityGuangzhou510655China
- Guangdong Research Institute of GastroenterologyThe Sixth Affiliated HospitalSun Yat‐sen UniversityGuangzhou510655China
| | - Daici Chen
- Guangdong Provincial Key Laboratory of Colorectal and Pelvic Floor DiseaseThe Sixth Affiliated HospitalSun Yat‐sen UniversityGuangzhou510655China
- Guangdong Research Institute of GastroenterologyThe Sixth Affiliated HospitalSun Yat‐sen UniversityGuangzhou510655China
| | - Qingxin Liu
- Guangdong Provincial Key Laboratory of Colorectal and Pelvic Floor DiseaseThe Sixth Affiliated HospitalSun Yat‐sen UniversityGuangzhou510655China
- Guangdong Research Institute of GastroenterologyThe Sixth Affiliated HospitalSun Yat‐sen UniversityGuangzhou510655China
| | - Baifu Qin
- Guangdong Provincial Key Laboratory of Colorectal and Pelvic Floor DiseaseThe Sixth Affiliated HospitalSun Yat‐sen UniversityGuangzhou510655China
- Guangdong Research Institute of GastroenterologyThe Sixth Affiliated HospitalSun Yat‐sen UniversityGuangzhou510655China
| | | | - Sai‐Ching J. Yeung
- Department of Emergency MedicineDivision of Internal MedicineThe University of Texas MD Anderson Cancer CenterHoustonTX77030USA
| | - Lekun Fang
- Guangdong Provincial Key Laboratory of Colorectal and Pelvic Floor DiseaseThe Sixth Affiliated HospitalSun Yat‐sen UniversityGuangzhou510655China
- Guangdong Research Institute of GastroenterologyThe Sixth Affiliated HospitalSun Yat‐sen UniversityGuangzhou510655China
- Department of Colorectal SurgeryThe Sixth Affiliated HospitalSun Yat‐sen UniversityGuangzhou510655China
| | - Mong‐Hong Lee
- Guangdong Provincial Key Laboratory of Colorectal and Pelvic Floor DiseaseThe Sixth Affiliated HospitalSun Yat‐sen UniversityGuangzhou510655China
- Guangdong Research Institute of GastroenterologyThe Sixth Affiliated HospitalSun Yat‐sen UniversityGuangzhou510655China
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Gao S, Fang L, Phan LM, Qdaisat A, Yeung SCJ, Lee MH. COP9 signalosome subunit 6 (CSN6) regulates E6AP/UBE3A in cervical cancer. Oncotarget 2016; 6:28026-41. [PMID: 26318036 PMCID: PMC4695042 DOI: 10.18632/oncotarget.4731] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Accepted: 07/23/2015] [Indexed: 02/03/2023] Open
Abstract
Cervical cancer is one of the leading causes of cancer death in women. Human papillomaviruses (HPVs) are the major cause in almost 99.7% of cervical cancer. E6 oncoprotein of HPV and E6-associated protein (E6AP) are critical in causing p53 degradation and malignancy. Understanding the E6AP regulation is critical to develop treating strategy for cervical cancer patients. The COP9 signalosome subunit 6 (CSN6) is involved in ubiquitin-mediated protein degradation. We found that both CSN6 and E6AP are overexpressed in cervical cancer. We characterized that CSN6 associated with E6AP and stabilized E6AP expression by reducing E6AP poly-ubiquitination, thereby regulating p53 activity in cell proliferation and apoptosis. Mechanistic studies revealed that CSN6-E6AP axis can be regulated by EGF/Akt signaling. Furthermore, inhibition of CSN6-E6AP axis hinders cervical cancer growth in mice. Taken together, our results indicate that CSN6 is a positive regulator of E6AP and is important for cervical cancer development.
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Affiliation(s)
- Shujun Gao
- Obstetrics and Gynecology Hospital Fudan University, Shanghai Key Laboratory of Female Reproductive Endocrine Related Diseases, Shanghai 200011, China.,Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
| | - Lekun Fang
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA.,Department of Colorectal Surgery, Guangdong Provincial Key Laboratory of Colorectal and Pelvic Floor Diseases, The Sixth Affiliated Hospital of Sun Yat-sen University, Guangzhou 510655, China
| | - Liem Minh Phan
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
| | - Aiham Qdaisat
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
| | - Sai-Ching J Yeung
- Department of Endocrine Neoplasia and Hormonal Disorders, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA.,Department of Emergency Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
| | - Mong-Hong Lee
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA.,Department of Colorectal Surgery, Guangdong Provincial Key Laboratory of Colorectal and Pelvic Floor Diseases, The Sixth Affiliated Hospital of Sun Yat-sen University, Guangzhou 510655, China.,Program in Cancer Biology, The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, TX 77030, USA.,Program in Genes and Development, The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, TX 77030, USA
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3
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Fang L, Lu W, Choi HH, Yeung SCJ, Tung JY, Hsiao CD, Fuentes-Mattei E, Menter D, Chen C, Wang L, Wang J, Lee MH. ERK2-Dependent Phosphorylation of CSN6 Is Critical in Colorectal Cancer Development. Cancer Cell 2015; 28:183-97. [PMID: 26267535 PMCID: PMC4560098 DOI: 10.1016/j.ccell.2015.07.004] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/25/2014] [Revised: 01/17/2015] [Accepted: 07/10/2015] [Indexed: 12/25/2022]
Abstract
Biomarkers for predicting prognosis are critical to treating colorectal cancer (CRC) patients. We found that CSN6, a subunit of COP9 signalosome, is overexpressed in CRC samples and that CSN6 overexpression is correlated with poor patient survival. Mechanistic studies revealed that CSN6 is deregulated by epidermal growth factor receptor (EGFR) signaling, in which ERK2 binds directly to CSN6 Leu163/Val165 and phosphorylates CSN6 at Ser148. Furthermore, CSN6 regulated β-Trcp and stabilized β-catenin expression by blocking the ubiquitin-proteasome pathway, thereby promoting CRC development. High CSN6 expression was positively correlated with ERK2 activation and β-catenin overexpression in CRC samples, and inhibiting CSN6 stability with cetuximab reduced colon cancer growth. Taken together, our study's findings indicate that the deregulation of β-catenin by ERK2-activated CSN6 is important for CRC development.
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Affiliation(s)
- Lekun Fang
- Department of Colorectal Surgery, The Sixth Affiliated Hospital of Sun Yat-sen University, Guangzhou 510655, China; Guangdong Provincial Key Laboratory of Colorectal and Pelvic Floor Disease, The Sixth Affiliated Hospital of Sun Yat-sen University, Guangzhou 510655, China; Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Weisi Lu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou 510060, China; Key Laboratory of Gene Engineering of the Ministry of Education, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China; Program in Genes and Development, The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, TX 77030, USA
| | - Hyun Ho Choi
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Sai-Ching J Yeung
- Department of Endocrine Neoplasia and Hormonal Disorders, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Jung-Yu Tung
- Institute of Molecular Biology, Academia Sinica, Taipei 11529, Taiwan
| | - Chwan-Deng Hsiao
- Institute of Molecular Biology, Academia Sinica, Taipei 11529, Taiwan
| | - Enrique Fuentes-Mattei
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - David Menter
- Department of Gastrointestinal Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Chuangqi Chen
- Department of Surgery, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou 510080, China
| | - Lei Wang
- Department of Colorectal Surgery, The Sixth Affiliated Hospital of Sun Yat-sen University, Guangzhou 510655, China; Guangdong Provincial Key Laboratory of Colorectal and Pelvic Floor Disease, The Sixth Affiliated Hospital of Sun Yat-sen University, Guangzhou 510655, China
| | - Jianping Wang
- Department of Colorectal Surgery, The Sixth Affiliated Hospital of Sun Yat-sen University, Guangzhou 510655, China; Guangdong Provincial Key Laboratory of Colorectal and Pelvic Floor Disease, The Sixth Affiliated Hospital of Sun Yat-sen University, Guangzhou 510655, China.
| | - Mong-Hong Lee
- Guangdong Provincial Key Laboratory of Colorectal and Pelvic Floor Disease, The Sixth Affiliated Hospital of Sun Yat-sen University, Guangzhou 510655, China; Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA; Program in Cancer Biology, The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, TX 77030, USA; Program in Genes and Development, The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, TX 77030, USA.
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Shin J, Phan L, Chen J, Lu Z, Lee MH. CSN6 positively regulates c-Jun in a MEKK1-dependent manner. Cell Cycle 2015; 14:3079-87. [PMID: 26237449 DOI: 10.1080/15384101.2015.1078030] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
c-Jun is a proto-oncoprotein that is commonly overexpressed in many types of cancer and is believed to regulate cell proliferation, the cell cycle, and apoptosis by controlling AP-1 activity. Understanding the c-Jun regulation is important to develop treatment strategy for cancer. The COP9 signalosome subunit 6 (CSN6) plays a critical role in ubiquitin-mediated protein degradation. MEKK1 is a serine/threonine kinase and E3 ligase containing PHD/RING domain involved in c-Jun ubiquitination. Here, we show that CSN6 associates with MEKK1 and reduces MEKK1 expression level by facilitating the ubiquitin-mediated degradation of MEKK1. Also we show that CSN6 overexpression diminishes MEKK1-mediated c-Jun ubiquitination, which is manifested in mitigating osmotic stress-mediated c-Jun downregulation. Thus, CSN6 is involved in positively regulating the stability of c-Jun. Overexpression of CSN6 correlates with the upregulation of c-Jun target gene expression in cancer. These findings provide new insight into CSN6-MEKK1-c-Jun axis in tumorigenesis.
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Affiliation(s)
- Jihyun Shin
- a Departments of Molecular and Cellular Oncology ; The University of Texas MD Anderson Cancer Center ; Houston , TX USA
| | - Liem Phan
- a Departments of Molecular and Cellular Oncology ; The University of Texas MD Anderson Cancer Center ; Houston , TX USA
| | - Jian Chen
- a Departments of Molecular and Cellular Oncology ; The University of Texas MD Anderson Cancer Center ; Houston , TX USA
| | - Zhimin Lu
- b Molecular pathology; The University of Texas MD Anderson Cancer Center ; Houston , TX USA
| | - Mong-Hong Lee
- a Departments of Molecular and Cellular Oncology ; The University of Texas MD Anderson Cancer Center ; Houston , TX USA
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5
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Base-CP proteasome can serve as a platform for stepwise lid formation. Biosci Rep 2015; 35:BSR20140173. [PMID: 26182356 PMCID: PMC4438304 DOI: 10.1042/bsr20140173] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2014] [Accepted: 01/26/2015] [Indexed: 12/14/2022] Open
Abstract
26S proteasome, a major regulatory protease in eukaryotes, consists of a 20S proteolytic core particle (CP) capped by a 19S regulatory particle (RP). The 19S RP is divisible into base and lid sub-complexes. Even within the lid, subunits have been demarcated into two modules: module 1 (Rpn5, Rpn6, Rpn8, Rpn9 and Rpn11), which interacts with both CP and base sub-complexes and module 2 (Rpn3, Rpn7, Rpn12 and Rpn15) that is attached mainly to module 1. We now show that suppression of RPN11 expression halted lid assembly yet enabled the base and 20S CP to pre-assemble and form a base-CP. A key role for Regulatory particle non-ATPase 11 (Rpn11) in bridging lid module 1 and module 2 subunits together is inferred from observing defective proteasomes in rpn11–m1, a mutant expressing a truncated form of Rpn11 and displaying mitochondrial phenotypes. An incomplete lid made up of five module 1 subunits attached to base-CP was identified in proteasomes isolated from this mutant. Re-introducing the C-terminal portion of Rpn11 enabled recruitment of missing module 2 subunits. In vitro, module 1 was reconstituted stepwise, initiated by Rpn11–Rpn8 heterodimerization. Upon recruitment of Rpn6, the module 1 intermediate was competent to lock into base-CP and reconstitute an incomplete 26S proteasome. Thus, base-CP can serve as a platform for gradual incorporation of lid, along a proteasome assembly pathway. Identification of proteasome intermediates and reconstitution of minimal functional units should clarify aspects of the inner workings of this machine and how multiple catalytic processes are synchronized within the 26S proteasome holoenzymes. Defective proteasome 19S regulatory particles (RPs) were identified in rpn11f–m1, a proteasomal mutant with mitochondrial phenotypes. The Rpn11 subunit initiates assembly of a five-subunit lid module competent to integrate into pre-assembled base-20S core particle (CP), with subsequent recruitment of remaining lid subunits.
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6
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Chen B, Zhao R, Su CH, Linan M, Tseng C, Phan L, Fang L, Yang HY, Yang H, Wang W, Xu X, Jiang N, Cai S, Jin F, Yeung SCJ, Lee MH. CDK inhibitor p57 (Kip2) is negatively regulated by COP9 signalosome subunit 6. Cell Cycle 2012. [PMID: 23187808 DOI: 10.4161/cc.22887] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Subunit 6 of the COP9 signalosome complex, CSN6, is known to be critical to the regulation of the MDM2-p53 axis for cell proliferation and anti-apoptosis, but its many targets remain unclear. Here we show that p57 (Kip2) is a target of CSN6, and that CSN6 is a negative regulator of p57 (Kip2) . CSN6 associates with p57 (Kip2) , and its overexpression can decrease the steady-state expression of p57 (Kip2) ; accordingly, CSN6 deficiency leads to p57 (Kip2) stabilization. Mechanistic studies show that CSN6 associates with p57 (Kip2) and Skp2, a component of the E3 ligase, which, in turn, facilitates Skp2-mediated protein ubiquitination of p57 (Kip2) . Loss of Skp2 compromised CSN6-mediated p57 (Kip2) destabilization, suggesting collaboration between Skp2 and CSN6 in degradation of p57 (Kip2) . CSN6's negative impact on p57 (Kip2) elevation translates into cell growth promotion, cell cycle deregulation and potentiated transformational activity. Significantly, univariate Kaplan-Meier analysis of tumor samples demonstrates that high CSN6 expression or low p57 expression is associated with poor overall survival. These data suggest that CSN6 is an important negative regulator of p57 (Kip2) , and that overexpression of CSN6 in many types of cancer could lead to decreased expression of p57 (Kip2) and result in promoted cancer cell growth.
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Affiliation(s)
- Bo Chen
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.
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7
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Xue Y, Chen J, Choi HH, Phan L, Chou PC, Zhao R, Yang H, Santiago J, Liu M, Yeung GE, Yeung SCJ, Lee MH. HER2-Akt signaling in regulating COP9 signalsome subunit 6 and p53. Cell Cycle 2012; 11:4181-90. [PMID: 23095642 DOI: 10.4161/cc.22413] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
HER2/neu oncogene is frequently overexpressed in various types of cancer, and the (PI3K)-Akt signaling pathway is often activated in HER2-overexpressing cancer cells. CSN6, subunit 6 of the COP9 signalosome complex, is pivotal in regulating MDM2 to destabilize p53, but its upstream regulators remain unclear. Here we show that the HER2-Akt axis is linked to CSN6 regulation, and that Akt is a positive regulator of CSN6. Ectopic expression of Akt can increase the expression of CSN6; accordingly, Akt inhibition leads to CSN6 destabilization. Mechanistic studies show that Akt causes CSN6 phosphorylation at Ser 60, which, in turn, reduces ubiquitin-mediated protein degradation of CSN6. Significantly, Akt's positive impact on CSN6 elevation translates into p53 degradation, potentiating transformational activity and increasing DNA damage. Akt inhibition can attenuate these defects caused by CSN6. These data suggest that Akt is an important positive regulator of CSN6, and that activation of Akt in many types of cancer could lead to abnormal elevation of CSN6 and result in downregulated p53 and increased DNA damage, which promotes cancer cell growth.
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Affiliation(s)
- Yuwen Xue
- Department of Pulmonary Medicine, Qilu Hospital of Shandong University, Jinan, Shandong, China
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Abstract
The constitutive photomorphogenesis 9 signalosome (COP9 or CSN) is an evolutionarily conserved multiprotein complex found in plants and animals. Because of the homology between the COP9 signalosome and the 19S lid complex of the proteosome, COP9 has been postulated to play a role in regulating the degradation of polyubiquitinated proteins. Many tumor suppressor and oncogene products are regulated by ubiquitination- and proteosome-mediated protein degradation. Therefore, it is conceivable that COP9 plays a significant role in cancer, regulating processes relevant to carcinogenesis and cancer progression (e.g., cell cycle control, signal transduction and apoptosis). In mammalian cells, it consists of eight subunits (CSN1 to CSN8). The relevance and importance of some subunits of COP9 to cancer are emerging. However, the mechanistic regulation of each subunit in cancer remains unclear. Among the CSN subunits, CSN5 and CSN6 are the only two that each contain an MPN (Mpr1p and Pad1p N-terminal) domain. The deneddylation activity of an MPN domain toward cullin-RING ubiquitin ligases (CRL) may coordinate CRL-mediated ubiquitination activity. More recent evidence shows that CSN5 and CSN6 are implicated in ubiquitin-mediated proteolysis of important mediators in carcinogenesis and cancer progression. Here, we discuss the mechanisms by which some CSN subunits are involved in cancer to provide a much needed perspective regarding COP9 in cancer research, hoping that these insights will lay the groundwork for cancer intervention.
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Affiliation(s)
- Mong-Hong Lee
- The University of Texas MD Anderson Cancer Center, Houston, TX, USA.
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9
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Zhang XC, Chen J, Su CH, Yang HY, Lee MH. Roles for CSN5 in control of p53/MDM2 activities. J Cell Biochem 2008; 103:1219-30. [PMID: 17879958 DOI: 10.1002/jcb.21504] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The 5th subunit of COP9 signalosome (CSN5, also known as Jab1 or COPS5) is implicated in regulating p53 activity and is overexpressed in various tumors. However, the precise roles of CSN5 in p53 network and tumorigenesis are not well characterized. Here we show that CSN5 is a critical regulator of both p53 and MDM2. We show that curcumin, an important inhibitor of CSN-associated kinases, can downregulate not only CSN5 but also MDM2, which results in p53 stabilization. Importantly, CSN5 interacts with p53. CSN5 expression leads to p53 degradation, facilitating MDM2-mediated p53 ubiquitination, and promoting p53 nuclear export. Additionally, CSN5 expression results in stabilization of MDM2 through reducing MDM2 self-ubiquitination and decelerating turnover rate of MDM2. Significantly, we further show that CSN5 antagonizes the transcriptional activity of p53. These results demonstrate that CSN5 is a pivotal regulator for both p53 and MDM2. Our studies may pave the way for targeting CSN5 for anti-cancer drug development.
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Affiliation(s)
- Xiao-Chun Zhang
- Department of Molecular and Cellular Oncology, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030, USA
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Voges D, Zwickl P, Baumeister W. The 26S proteasome: a molecular machine designed for controlled proteolysis. Annu Rev Biochem 2000; 68:1015-68. [PMID: 10872471 DOI: 10.1146/annurev.biochem.68.1.1015] [Citation(s) in RCA: 1377] [Impact Index Per Article: 57.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
In eukaryotic cells, most proteins in the cytosol and nucleus are degraded via the ubiquitin-proteasome pathway. The 26S proteasome is a 2.5-MDa molecular machine built from approximately 31 different subunits, which catalyzes protein degradation. It contains a barrel-shaped proteolytic core complex (the 20S proteasome), capped at one or both ends by 19S regulatory complexes, which recognize ubiquitinated proteins. The regulatory complexes are also implicated in unfolding and translocation of ubiquitinated targets into the interior of the 20S complex, where they are degraded to oligopeptides. Structure, assembly and enzymatic mechanism of the 20S complex have been elucidated, but the functional organization of the 19S complex is less well understood. Most subunits of the 19S complex have been identified, however, specific functions have been assigned to only a few. A low-resolution structure of the 26S proteasome has been obtained by electron microscopy, but the precise arrangement of subunits in the 19S complex is unclear.
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Affiliation(s)
- D Voges
- Max-Planck-Institut für Biochemie, Martinsried, Germany
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Lutz MS, Ellis SR, Martin NC. Proteasome mutants, pre4-2 and ump1-2, suppress the essential function but not the mitochondrial RNase P function of the Saccharomyces cerevisiae gene RPM2. Genetics 2000; 154:1013-23. [PMID: 10757750 PMCID: PMC1460975 DOI: 10.1093/genetics/154.3.1013] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The Saccharomyces cerevisiae nuclear gene RPM2 encodes a component of the mitochondrial tRNA-processing enzyme RNase P. Cells grown on fermentable carbon sources do not require mitochondrial tRNA processing activity, but still require RPM2, indicating an additional function for the Rpm2 protein. RPM2-null cells arrest after 25 generations on fermentable media. Spontaneous mutations that suppress arrest occur with a frequency of approximately 9 x 10(-6). The resultant mutants do not grow on nonfermentable carbon sources. We identified two loci responsible for this suppression, which encode proteins that influence proteasome function or assembly. PRE4 is an essential gene encoding the beta-7 subunit of the 20S proteasome core. A Val-to-Phe substitution within a highly conserved region of Pre4p that disrupts proteasome function suppresses the growth arrest of RPM2-null cells on fermentable media. The other locus, UMP1, encodes a chaperone involved in 20S proteasome assembly. A nonsense mutation in UMP1 also disrupts proteasome function and suppresses Deltarpm2 growth arrest. In an RPM2 wild-type background, pre4-2 and ump1-2 strains fail to grow at restrictive temperatures on nonfermentable carbon sources. These data link proteasome activity with Rpm2p and mitochondrial function.
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Affiliation(s)
- M S Lutz
- Department of Biochemistry and Molecular Biology, University of Louisville, Louisville, Kentucky 40292, USA
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Rinaldi T, Ricci C, Porro D, Bolotin-Fukuhara M, Frontali L. A mutation in a novel yeast proteasomal gene, RPN11/MPR1, produces a cell cycle arrest, overreplication of nuclear and mitochondrial DNA, and an altered mitochondrial morphology. Mol Biol Cell 1998; 9:2917-31. [PMID: 9763452 PMCID: PMC25568 DOI: 10.1091/mbc.9.10.2917] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
We report here the functional characterization of an essential Saccharomyces cerevisiae gene, MPR1, coding for a regulatory proteasomal subunit for which the name Rpn11p has been proposed. For this study we made use of the mpr1-1 mutation that causes the following pleiotropic defects. At 24 degreesC growth is delayed on glucose and impaired on glycerol, whereas no growth is seen at 36 degreesC on either carbon source. Microscopic observation of cells growing on glucose at 24 degreesC shows that most of them bear a large bud, whereas mitochondrial morphology is profoundly altered. A shift to the nonpermissive temperature produces aberrant elongated cell morphologies, whereas the nucleus fails to divide. Flow cytometry profiles after the shift to the nonpermissive temperature indicate overreplication of both nuclear and mitochondrial DNA. Consistently with the identification of Mpr1p with a proteasomal subunit, the mutation is complemented by the human POH1 proteasomal gene. Moreover, the mpr1-1 mutant grown to stationary phase accumulates ubiquitinated proteins. Localization of the Rpn11p/Mpr1p protein has been studied by green fluorescent protein fusion, and the fusion protein has been found to be mainly associated to cytoplasmic structures. For the first time, a proteasomal mutation has also revealed an associated mitochondrial phenotype. We actually showed, by the use of [rho degrees] cells derived from the mutant, that the increase in DNA content per cell is due in part to an increase in the amount of mitochondrial DNA. Moreover, microscopy of mpr1-1 cells grown on glucose showed that multiple punctate mitochondrial structures were present in place of the tubular network found in the wild-type strain. These data strongly suggest that mpr1-1 is a valuable tool with which to study the possible roles of proteasomal function in mitochondrial biogenesis.
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Affiliation(s)
- T Rinaldi
- Pasteur Institute-Cenci Bolognetti Foundation, Department of Cell and Developmental Biology, University of Rome "La Sapienza", 00185 Rome, Italy. Rinaldit.axcasp.caspur.it
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Penney M, Wilkinson C, Wallace M, Javerzat JP, Ferrell K, Seeger M, Dubiel W, McKay S, Allshire R, Gordon C. The Pad1+ gene encodes a subunit of the 26 S proteasome in fission yeast. J Biol Chem 1998; 273:23938-45. [PMID: 9727008 DOI: 10.1074/jbc.273.37.23938] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have isolated a fission yeast mutant, mts5-1, in a screen for mutations that confer both methyl 2-benzimidazolecarbamate resistance (MBCR) and temperature sensitivity (ts) on Schizosaccharomyces pombe. This screen has previously isolated mutations in the 26 S proteasome subunits Mts2, Mts3, and Mts4. We show that the mutation in the mts5-1 strain occurs in the pad1(+) gene. pad1(+) was originally isolated on a multicopy plasmid that was capable of conferring staurosporine resistance on a wild type strain. mts5-1/pad1-1 has a similar phenotype to 26 S proteasome mutants previously isolated in the same screen and we show that Pad1 interacts genetically with two of these subunits, Mts3 and Mts4. In this study we describe the identification of Pad1 as a subunit of the 26 S proteasome in fission yeast.
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Affiliation(s)
- M Penney
- MRC Human Genetics Unit Western General Hospital, Edinburgh EH4 2XU Scotland, United Kingdom
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Glickman MH, Rubin DM, Fried VA, Finley D. The regulatory particle of the Saccharomyces cerevisiae proteasome. Mol Cell Biol 1998; 18:3149-62. [PMID: 9584156 PMCID: PMC108897 DOI: 10.1128/mcb.18.6.3149] [Citation(s) in RCA: 397] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/1997] [Accepted: 03/09/1998] [Indexed: 02/07/2023] Open
Abstract
The proteasome is a multisubunit protease responsible for degrading proteins conjugated to ubiquitin. The 670-kDa core particle of the proteasome contains the proteolytic active sites, which face an interior chamber within the particle and are thus protected from the cytoplasm. The entry of substrates into this chamber is thought to be governed by the regulatory particle of the proteasome, which covers the presumed channels leading into the interior of the core particle. We have resolved native yeast proteasomes into two electrophoretic variants and have shown that these represent core particles capped with one or two regulatory particles. To determine the subunit composition of the regulatory particle, yeast proteasomes were purified and analyzed by gradient sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Resolution of the individual polypeptides revealed 17 distinct proteins, whose identities were determined by amino acid sequence analysis. Six of the subunits have sequence features of ATPases (Rpt1 to Rpt6). Affinity chromatography was used to purify regulatory particles from various strains, each of which expressed one of the ATPases tagged with hexahistidine. In all cases, multiple untagged ATPases copurified, indicating that the ATPases assembled together into a heteromeric complex. Of the remaining 11 subunits that we have identified (Rpn1 to Rpn3 and Rpn5 to Rpn12), 8 are encoded by previously described genes and 3 are encoded by genes not previously characterized for yeasts. One of the previously unidentified subunits exhibits limited sequence similarity with deubiquitinating enzymes. Overall, regulatory particles from yeasts and mammals are remarkably similar, suggesting that the specific mechanistic features of the proteasome have been closely conserved over the course of evolution.
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Affiliation(s)
- M H Glickman
- Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115, USA
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Asano K, Vornlocher HP, Richter-Cook NJ, Merrick WC, Hinnebusch AG, Hershey JW. Structure of cDNAs encoding human eukaryotic initiation factor 3 subunits. Possible roles in RNA binding and macromolecular assembly. J Biol Chem 1997; 272:27042-52. [PMID: 9341143 DOI: 10.1074/jbc.272.43.27042] [Citation(s) in RCA: 139] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The mammalian translation initiation factor 3 (eIF3), is a multiprotein complex of approximately 600 kDa that binds to the 40 S ribosome and promotes the binding of methionyl-tRNAi and mRNA. cDNAs encoding 5 of the 10 subunits, namely eIF3-p170, -p116, -p110, -p48, and -p36, have been isolated previously. Here we report the cloning and characterization of human cDNAs encoding the major RNA binding subunit, eIF3-p66, and two additional subunits, eIF3-p47 and eIF3-p40. Each of these proteins is present in immunoprecipitates formed with affinity-purified anti-eIF3-p170 antibodies. Human eIF3-p66 shares 64% sequence identity with a hypothetical Caenorhabditis elegans protein, presumably the p66 homolog. Deletion analyses of recombinant derivatives of eIF3-p66 show that the RNA-binding domain lies within an N-terminal 71-amino acid region rich in lysine and arginine. The N-terminal regions of human eIF3-p40 and eIF3-p47 are related to each other and to 17 other eukaryotic proteins, including murine Mov-34, a subunit of the 26 S proteasome. Phylogenetic analyses of the 19 related protein sequences, called the Mov-34 family, distinguish five major subgroups, where eIF3-p40, eIF3-p47, and Mov-34 are each found in a different subgroup. The subunit composition of eIF3 appears to be highly conserved in Drosophila melanogaster, C. elegans, and Arabidopsis thaliana, whereas only 5 homologs of the 10 subunits of mammalian eIF3 are encoded in S. cerevisiae.
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Affiliation(s)
- K Asano
- Department of Biological Chemistry, School of Medicine, University of California, Davis, California 95616, USA
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Papadimitriou A, Gross HJ. Pre-tRNA 3'-processing in Saccharomyces cerevisiae. Purification and characterization of exo- and endoribonucleases. EUROPEAN JOURNAL OF BIOCHEMISTRY 1996; 242:747-59. [PMID: 9022706 DOI: 10.1111/j.1432-1033.1996.0747r.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
We investigated ribonucleases from Saccharomyces cerevisiae which are active in pre-tRNA 3'-processing in vitro. Two pre-tRNA 3'-exonucleases with molecular masses of 33 and 60 kDa, two pre-tRNA 3'-endonucleases with molecular masses of 45 kDa/60 kDa and 55 kDa and 70-kDa 3'-pre-tRNase were purified from yeast whole cell extracts by several successive chromatographic purification steps. The purified exonucleases are non-processive 3'-exonucleases that catalyze the exonucleolytic processing of 3'-trailer sequences of pre-tRNAs to produce mature tRNAs. The 45-kDa/60-kDa 3'-endonuclease is tRNA-specific and catalyzes the processing of pre-tRNAs in a single endonucleolytic step. Two isoenzymes of this activity (p45 and p60) were identified by chromatography. The second endonuclease, p55, is dependent on monovalent ions and cleaves about three nucleotides downstream the mature 3'-end. All of the purified 3'-pre-tRNases accept homologous as well as heterologous pre-tRNA substrates. Pre-tRNAs carrying a 5'-leader are processed with almost the same efficiency as those lacking this 5'-leader. Mature tRNAs carrying the CCA 3'-sequence and tRNA pseudogene products carrying mutations in the mature domain are processed by the 3'-exonucleases, not by the 3'-endonucleases. The specific endonuclease p45/p60 discriminates between UUUOH as a 3'-flank, which is cleaved, and the CCA 3'-end of mature tRNAs, which is not cleaved. This study suggests that several 3'-pre-tRNases are active on tRNA precursors in vitro and might therefore in pre-tRNA 3'-processing in yeast, partly in a cooperative manner.
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Affiliation(s)
- A Papadimitriou
- Institut für Biochemie, Bayerische Julius-Maximilians-Universität, Biozentrum, Würzburg, Germany
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