1
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Wang LL, Wan XY, Liu CQ, Zheng FM. NDR1 increases NOTCH1 signaling activity by impairing Fbw7 mediated NICD degradation to enhance breast cancer stem cell properties. Mol Med 2022; 28:49. [PMID: 35508987 PMCID: PMC9066784 DOI: 10.1186/s10020-022-00480-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2021] [Accepted: 04/18/2022] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND The existence of breast cancer stem cells (BCSCs) causes tumor relapses, metastasis and resistance to conventional therapy in breast cancer. NDR1 kinase, a component of the Hippo pathway, plays important roles in multiple biological processes. However, its role in cancer stem cells has not been explored. The purpose of this study was to investigate the roles of NDR1 in modulating BCSCs. METHODS The apoptosis was detected by Annexin V/Propidium Iodide staining and analyzed by flow cytometry. BCSCs were detected by CD24/44 or ALDEFLUOR staining and analyzed by flow cytometry. The proliferation ability of BCSCs was evaluated by sphere formation assay. The expression of interested proteins was detected by western blot analysis. The expression of HES-1 and c-MYC was detected by real-time PCR. Notch1 signaling activation was detected by luciferase reporter assay. Protein interaction was evaluated by immunoprecipitation. Protein degradation was evaluated by ubiquitination analysis. The clinical relevance of NDR1 was analyzed by Kaplan-Meier Plotter. RESULTS NDR1 regulates apoptosis and drug resistance in breast cancer cells. The upregulation of NDR1 increases CD24low/CD44high or ALDEFLUORhigh population and sphere-forming ability in SUM149 and MCF-7 cells, while downregulation of NDR1 induces opposite effects. NDR1 increased the expression of the Notch1 intracellular domain (NICD) and activated the transcription of its downstream target (HES-1 and c-MYC). Critically, both suppression of Notch pathway activation by DAPT treatment or downregulation of Notch1 expression by shRNA reverses NDR1 enhanced BCSC properties. Mechanically, NDR1 interactes with both NICD or Fbw7 in a kinase activity-independent manner. NDR1 reduces the proteolytic turnover of NICD by competing with Fbw7 for NICD binding, thereby leading to Notch pathway activation. Furthermore, NDR1 might function as a hub to modulate IL-6, TNF-α or Wnt3a induced activation of Notch1 signaling pathway and enrichment of breast cancer stem cells. Moreover, we find that the elevation of NDR1 expression predictes poor survival (OS, RFS, DMFS and PPS) in breast cancer. CONCLUSION Our study revealed a novel function of NDR1 in regulating BCSC properties by activating the Notch pathway. These data might provide a potential strategy for eradicating BCSC to overcome tumor relapses, metastasis and drug resistance.
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Affiliation(s)
- Ling-Ling Wang
- Department of Medical Oncology of The Eastern Hospital, The First Affiliated Hospital, Sun Yat-Sen University, No.58, Zhong Shan Er Lu, Guangzhou, 510080, China.,Guangdong Provincial Key Laboratory of Orthopedics and Traumatology, The First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, China
| | - Xiao-Yun Wan
- Department of Medical Oncology, Guangzhou Panyu Hospital of Chinese Medicine, Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Chun-Qi Liu
- Department of Thoracic Surgery, Panyu Central Hospital, Guangzhou, China
| | - Fei-Meng Zheng
- Department of Medical Oncology of The Eastern Hospital, The First Affiliated Hospital, Sun Yat-Sen University, No.58, Zhong Shan Er Lu, Guangzhou, 510080, China. .,Guangdong Provincial Key Laboratory of Orthopedics and Traumatology, The First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, China.
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2
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Tang M, Xie X, Shi M, Xin W, Zheng G, Zhang Y, Zhang Z, Lian X. Antileukemic effect of caffeic acid 3,4-dihydroxyphenetyl ester. Evidences for its mechanisms of action. Phytomedicine 2021; 80:153383. [PMID: 33091855 DOI: 10.1016/j.phymed.2020.153383] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Revised: 10/11/2020] [Accepted: 10/12/2020] [Indexed: 06/11/2023]
Abstract
BACKGROUND Caffeic acid 3,4-dihydroxyphenethyl ester (CADPE) is a natural polyphenolic ester isolated as a minor component from a water extract of the Chinese medicine Zhongjiefeng [Sarcandra glabra (Thunb.) Nakai (Chloranthaceae)] and has previously shown to have activity against solid tumors through the modulation of multiple targets or signal pathways. However, the activity and potential mechanism of CADPE against leukemia cells have not yet been characterized. PURPOSE To investigate whether and how CADPE kills leukemia cells. METHOD (1) The activity of CADPE inhibiting the growth of different leukemia cell lines was evaluated by MTT assay; (2) Cell cycle arrest and apoptosis induced by CADPE were determined by flow cytometry with FlowJo software for quantification; (3) The protein levels were analyzed by Western blot and ubiquitin-binding c-Myc was acquired by co-immunoprecipitation. RESULTS CADPE exerted potent activity against different leukemia cell lines with low toxicity in normal cells. In terms of mechanism of action, CADPE promoted ubiquitin-proteasome-dependent degradation of c-Myc through activating glycogen synthase kinase-3β (GSK3β) and downregulating deubiquitinating enzyme USP28 to trigger the interaction of c-Myc with ubiquitin ligase Fbw7, resulting in the downregulation of cell cycle regulators and anti-apoptotic proteins and consequently, cell cycle arrest and cell apoptosis. CONCLUSION CADPE is a novel c-Myc inhibitor with high activity and a unique mechanism for killing leukemia cells.
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Affiliation(s)
- Mingmin Tang
- College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China
| | - Xin Xie
- Zhejiang Center for Medical Device Evaluation, Hangzhou 310009, China
| | - Muran Shi
- College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China
| | - Wenxiu Xin
- Department of Pharmacy, Zhejiang Cancer Hospital, Hangzhou 310022, China
| | - Guowan Zheng
- College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China
| | - Yanhua Zhang
- College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China
| | - Zhizhen Zhang
- Ocean College, Zhoushan Campus, Zhejiang University, Zhoushan 316021, China.
| | - Xiaoyuan Lian
- College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China.
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3
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Meyer AE, Furumo Q, Stelloh C, Minella AC, Rao S. Loss of Fbxw7 triggers mammary tumorigenesis associated with E2F/c-Myc activation and Trp53 mutation. Neoplasia 2020; 22:644-658. [PMID: 33070870 PMCID: PMC7573506 DOI: 10.1016/j.neo.2020.07.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Revised: 06/30/2020] [Accepted: 07/02/2020] [Indexed: 12/18/2022]
Abstract
Fbw7 is a tumor suppressor that regulates the degradation of oncogenic substrates such as c-Jun, c-Myc, Notch1 intracellular domain (ICD), and cyclin E by functioning as the substrate recognition protein in the Skp1-Cullin-F-box (SCF) ubiquitin ligase complex. Consequently, low expression or loss of FBXW7 in breast cancer has been hypothesized to result in the accumulation of oncogenic transcription factors that are master regulators of proliferation, apoptosis, and ultimately transformation. Despite this, the direct effect of Fbw7 loss on mammary gland morphology and tumorigenesis has not been examined. Here, we demonstrate that conditional deletion of Fbxw7 in murine mammary tissue initiates breast tumor development and also results in lactation and involution defects. Further, while Fbxw7 loss results in the overexpression of Notch1-ICD, c-Jun, cyclin E, and c-Myc, the downstream transcription factor pathways associated with c-Myc and cyclin E are the most dysregulated, including at the single-cell level. These pathways are dysregulated early after Fbxw7 loss, and their sustained loss results in tumorigenesis and reinforced c-Myc and cyclin E-E2F pathway disruption. We also find that loss of Fbxw7 is linked to the acquisition of Trp53 mutations, similar to the mutational spectrum observed in patients. Our results demonstrate that the loss of Fbxw7 promotes the acquisition of Trp53 mutations and that the two cooperate in breast tumor development. Targeting c-Myc, E2F, or p53 may therefore be a beneficial treatment strategy for FBXW7-altered breast cancer patients.
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Affiliation(s)
- Alison E Meyer
- Blood Research Institute, Versiti, 8727 Watertown Plank Rd., Milwaukee, WI 53226, USA.
| | - Quinlan Furumo
- Blood Research Institute, Versiti, 8727 Watertown Plank Rd., Milwaukee, WI 53226, USA.
| | - Cary Stelloh
- Blood Research Institute, Versiti, 8727 Watertown Plank Rd., Milwaukee, WI 53226, USA.
| | - Alex C Minella
- Blood Research Institute, Versiti, 8727 Watertown Plank Rd., Milwaukee, WI 53226, USA.
| | - Sridhar Rao
- Blood Research Institute, Versiti, 8727 Watertown Plank Rd., Milwaukee, WI 53226, USA; Departments of Cell Biology, Neurobiology, and Anatomy, and Pediatrics, Medical College of Wisconsin, 8701 Watertown Plank Rd., Milwaukee, WI 53226, USA.
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4
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Hoshikawa S, Shimizu K, Watahiki A, Chiba M, Saito K, Wei W, Fukumoto S, Inuzuka H. Phosphorylation-dependent osterix degradation negatively regulates osteoblast differentiation. FASEB J 2020; 34:14930-14945. [PMID: 32931083 DOI: 10.1096/fj.202001340r] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 08/15/2020] [Accepted: 08/25/2020] [Indexed: 01/05/2023]
Abstract
Proteasome inhibitors exert an anabolic effect on bone formation with elevated levels of osteoblast markers. These findings suggest the important role of the proteasomal degradation of osteogenic regulators, while the underlying molecular mechanisms are not fully understood. Here, we report that the proteasome inhibitors bortezomib and ixazomib markedly increased protein levels of the osteoblastic key transcription factor osterix/Sp7 (Osx). Furthermore, we revealed that Osx was targeted by p38 and Fbw7 for proteasomal degradation. Mechanistically, p38-mediated Osx phosphorylation at S73/77 facilitated Fbw7 interaction to trigger subsequent Osx ubiquitination. Consistent with these findings, p38 knockdown or pharmacological p38 inhibition resulted in Osx protein stabilization. Treatment with p38 inhibitors following osteogenic stimulation efficiently induced osteoblast differentiation through Osx stabilization. Conversely, pretreatment of p38 inhibitor followed by osteogenic challenge impaired osteoblastogenesis via suppressing Osx expression, suggesting that p38 exerts dual but opposite effects in the regulation of Osx level to fine-tune its activity during osteoblast differentiation. Furthermore, Fbw7-depleted human mesenchymal stem cells and primary mouse calvarial cells resulted in increased osteogenic capacity. Together, our findings unveil the molecular mechanisms underlying the Osx protein stability control and suggest that targeting the Osx degradation pathway could help enhance efficient osteogenesis and bone matrix regeneration.
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Affiliation(s)
- Seira Hoshikawa
- Division of Pediatric Dentistry, Department of Oral Health and Development Sciences, Tohoku University Graduate School of Dentistry, Sendai, Japan.,Center for Advanced Stem Cell and Regenerative Research, Tohoku University Graduate School of Dentistry, Sendai, Japan
| | - Kouhei Shimizu
- Center for Advanced Stem Cell and Regenerative Research, Tohoku University Graduate School of Dentistry, Sendai, Japan
| | - Asami Watahiki
- Center for Advanced Stem Cell and Regenerative Research, Tohoku University Graduate School of Dentistry, Sendai, Japan
| | - Mitsuki Chiba
- Division of Pediatric Dentistry, Department of Oral Health and Development Sciences, Tohoku University Graduate School of Dentistry, Sendai, Japan.,Center for Advanced Stem Cell and Regenerative Research, Tohoku University Graduate School of Dentistry, Sendai, Japan
| | - Kan Saito
- Division of Pediatric Dentistry, Department of Oral Health and Development Sciences, Tohoku University Graduate School of Dentistry, Sendai, Japan
| | - Wenyi Wei
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Satoshi Fukumoto
- Division of Pediatric Dentistry, Department of Oral Health and Development Sciences, Tohoku University Graduate School of Dentistry, Sendai, Japan.,Center for Advanced Stem Cell and Regenerative Research, Tohoku University Graduate School of Dentistry, Sendai, Japan.,Department of Pediatric Dentistry, Kyushu University Graduate School of Dental Science, Fukuoka, Japan
| | - Hiroyuki Inuzuka
- Center for Advanced Stem Cell and Regenerative Research, Tohoku University Graduate School of Dentistry, Sendai, Japan
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5
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Affiliation(s)
- Souhila Medjkane
- Université de Paris, UMR 7216 Epigenetics and Cell Fate, CNRS, Paris, France
| | - Jonathan B Weitzman
- Université de Paris, UMR 7216 Epigenetics and Cell Fate, CNRS, Paris, France
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6
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Tripathi V, Kaur E, Kharat SS, Hussain M, Damodaran AP, Kulshrestha S, Sengupta S. Abrogation of FBW7α-dependent p53 degradation enhances p53's function as a tumor suppressor. J Biol Chem 2019; 294:13224-13232. [PMID: 31346036 DOI: 10.1074/jbc.ac119.008483] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Revised: 07/15/2019] [Indexed: 12/12/2022] Open
Abstract
The gene encoding the tumor suppressor p53 is mutated in most cancers. p53 expression is known to be tightly controlled by several E3 ligases. Here, we show that F-box and WD repeat domain-containing 7α (FBW7α), the substrate-recognition component of the SCFFBW7 multiprotein E3 ligase complex, targets both WT and tumor-derived mutants of p53 for proteasomal degradation in multiple human cancer cell lines (HCT116 and U2OS). We found that lack of FBW7α stabilizes p53 levels, thereby increasing its half-life. p53 ubiquitylation and subsequent degradation require the F-box and the C-terminal WD40 repeats in FBW7α. The polyubiquitylation of p53 occurred via Lys-48 linkage and involved phosphorylation on p53 at Ser-33 and Ser-37 by glycogen synthase kinase 3β (GSK3β) and DNA-dependent protein kinase (DNA-PK), respectively. These phosphorylation events created a phosphodegron that enhanced p53 binding to FBW7α, allowing for the attachment of polyubiquitin moieties at Lys-132 in p53. FBW7α-dependent p53 polyubiquitylation apparently occurred during and immediately after DNA double-strand breaks induced by either doxorubicin or ionizing radiation. Accordingly, in cells lacking FBW7α, p53 induction was enhanced after DNA damage. Phosphodegron-mediated polyubiquitylation of p53 on Lys-132 had functional consequences, with cells in which FBW7α-mediated p53 degradation was abrogated exhibiting enhancement of their tumorigenic potential. We conclude that p53, which previously has been reported to transactivate FBW7, is also targeted by the same E3 ligase for degradation, suggesting the presence of a regulatory feedback loop that controls p53 levels and functions during DNA damage.
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Affiliation(s)
- Vivek Tripathi
- National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi 110067, India
| | - Ekjot Kaur
- National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi 110067, India
| | - Suhas Sampat Kharat
- National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi 110067, India
| | - Mansoor Hussain
- National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi 110067, India
| | | | - Swati Kulshrestha
- National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi 110067, India
| | - Sagar Sengupta
- National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi 110067, India.
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7
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Davis RJ, Gönen M, Margineantu DH, Handeli S, Swanger J, Hoellerbauer P, Paddison PJ, Gu H, Raftery D, Grim JE, Hockenbery DM, Margolin AA, Clurman BE. Pan-cancer transcriptional signatures predictive of oncogenic mutations reveal that Fbw7 regulates cancer cell oxidative metabolism. Proc Natl Acad Sci U S A 2018; 115:5462-7. [PMID: 29735700 DOI: 10.1073/pnas.1718338115] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The Fbw7 (F-box/WD repeat-containing protein 7) ubiquitin ligase targets multiple oncoproteins for degradation and is commonly mutated in cancers. Like other pleiotropic tumor suppressors, Fbw7's complex biology has impeded our understanding of how Fbw7 mutations promote tumorigenesis and hindered the development of targeted therapies. To address these needs, we employed a transfer learning approach to derive gene-expression signatures from The Cancer Gene Atlas datasets that predict Fbw7 mutational status across tumor types and identified the pathways enriched within these signatures. Genes involved in mitochondrial function were highly enriched in pan-cancer signatures that predict Fbw7 mutations. Studies in isogenic colorectal cancer cell lines that differed in Fbw7 mutational status confirmed that Fbw7 mutations increase mitochondrial gene expression. Surprisingly, Fbw7 mutations shifted cellular metabolism toward oxidative phosphorylation and caused context-specific metabolic vulnerabilities. Our approach revealed unexpected metabolic reprogramming and possible therapeutic targets in Fbw7-mutant cancers and provides a framework to study other complex, oncogenic mutations.
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8
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Yao S, Xu F, Chen Y, Ge Y, Zhang F, Huang H, Li L, Lin D, Luo X, Xu J, Luo D, Zhu X, Liu Y. Fbw7 regulates apoptosis in activated B-cell like diffuse large B-cell lymphoma by targeting Stat3 for ubiquitylation and degradation. J Exp Clin Cancer Res 2017; 36:10. [PMID: 28069035 PMCID: PMC5223361 DOI: 10.1186/s13046-016-0476-y] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/20/2016] [Accepted: 12/14/2016] [Indexed: 01/10/2023]
Abstract
Background The ubiquitin-ligase Fbw7 acts as a tumor suppressor, targeting lots of proto-oncogenes for proteolysis. However, the exact role of Fbw7 in diffuse large B-cell lymphoma (DLBCL) development remains unclear. Methods We evaluated Fbw7 expression in patient samples of DLBCL using immunohistochemical staining. The effect of Fbw7 overexpression on cell viability and apoptosis was investigated using activated B-cell (ABC) like DLBCL cell lines. The mechanism of Fbw7 activity in DLBCL was investigated using immunoprecipitation, ubiquitination, western blot and qualitative analyses. Results The non-germinal center B-cell-like subtype of DLBCL showed reduced Fbw7 expression compared with the germinal center B-cell (GBC) subtype, and low Fbw7 expression was associated with a worse prognosis. Fbw7 overexpression caused decreased cell viability and increased apoptosis rates in the ABC-DLBCL cell lines SU-DHL-2 and OCI-LY-3. Importantly, Stat3 and phospho-Stat3Tyr705 stability were reduced following Fbw7 overexpression in ABC-DLBCL cell lines. In HEK293T and SU-DHL-2 cells, we demonstrated that Fbw7 interacts with Stat3 and pStat3Tyr705 to regulate their ubiquitylation and degradation. Downstream anti-apoptotic target genes of activated Stat3, including Myc, Survivin, Mcl-1, Pim-1, Bcl-2 and Bcl-xl showed decreased mRNA expression following exogenous Fbw7 overexpression. The negative relationship between Fbw7 and pStat3Tyr705 levels was also confirmed in DLBCL patient samples. Conclusion The ubiquitin-ligase Fbw7 mediates apoptosis through targeting Stat3 for ubiquitylation and degradation in ABC-DLBCL. Thus, our study may offer a promising approach for ABC-DLBCL therapy through Stat3 inhibition. Electronic supplementary material The online version of this article (doi:10.1186/s13046-016-0476-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Su Yao
- Department of Pathology, Guangdong General Hospital & Guangdong Academy of Medical Sciences, Guangzhou, Guangdong, 510080, People's Republic of China
| | - Fangping Xu
- Department of Pathology, Guangdong General Hospital & Guangdong Academy of Medical Sciences, Guangzhou, Guangdong, 510080, People's Republic of China
| | - Yu Chen
- Department of Pathology, Guangdong General Hospital & Guangdong Academy of Medical Sciences, Guangzhou, Guangdong, 510080, People's Republic of China
| | - Yan Ge
- Department of Pathology, Guangdong General Hospital & Guangdong Academy of Medical Sciences, Guangzhou, Guangdong, 510080, People's Republic of China
| | - Fen Zhang
- Department of Pathology, Guangdong General Hospital & Guangdong Academy of Medical Sciences, Guangzhou, Guangdong, 510080, People's Republic of China
| | - Huijie Huang
- Department of Pathology, Dongguan People's Hospital, Dongguan, Guangdong, 523059, People's Republic of China
| | - Li Li
- Department of Pathology, Guangdong General Hospital & Guangdong Academy of Medical Sciences, Guangzhou, Guangdong, 510080, People's Republic of China
| | - Danyi Lin
- Department of Pathology, Guangdong General Hospital & Guangdong Academy of Medical Sciences, Guangzhou, Guangdong, 510080, People's Republic of China
| | - Xinlan Luo
- Department of Pathology, Guangdong General Hospital & Guangdong Academy of Medical Sciences, Guangzhou, Guangdong, 510080, People's Republic of China
| | - Jie Xu
- Department of Pathology, Guangdong General Hospital & Guangdong Academy of Medical Sciences, Guangzhou, Guangdong, 510080, People's Republic of China
| | - Donglan Luo
- Department of Pathology, Guangdong General Hospital & Guangdong Academy of Medical Sciences, Guangzhou, Guangdong, 510080, People's Republic of China
| | - Xiaolan Zhu
- Department of Pathology, Guangdong General Hospital & Guangdong Academy of Medical Sciences, Guangzhou, Guangdong, 510080, People's Republic of China
| | - Yanhui Liu
- Department of Pathology, Guangdong General Hospital & Guangdong Academy of Medical Sciences, Guangzhou, Guangdong, 510080, People's Republic of China.
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9
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Xiao D, Yue M, Su H, Ren P, Jiang J, Li F, Hu Y, Du H, Liu H, Qing G. Polo-like Kinase-1 Regulates Myc Stabilization and Activates a Feedforward Circuit Promoting Tumor Cell Survival. Mol Cell 2016; 64:493-506. [PMID: 27773673 DOI: 10.1016/j.molcel.2016.09.016] [Citation(s) in RCA: 107] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Revised: 08/17/2016] [Accepted: 09/14/2016] [Indexed: 01/19/2023]
Abstract
MYCN amplification in human cancers predicts poor prognosis and resistance to therapy. However, pharmacological strategies that directly target N-Myc, the protein encoded by MYCN, remain elusive. Here, we identify a molecular mechanism responsible for reciprocal activation between Polo-like kinase-1 (PLK1) and N-Myc. PLK1 specifically binds to the SCFFbw7 ubiquitin ligase, phosphorylates it, and promotes its autopolyubiquitination and proteasomal degradation, counteracting Fbw7-mediated degradation of N-Myc and additional substrates, including cyclin E and Mcl1. Stabilized N-Myc in turn directly activates PLK1 transcription, constituting a positive feedforward regulatory loop that reinforces Myc-regulated oncogenic programs. Inhibitors of PLK1 preferentially induce potent apoptosis of MYCN-amplified tumor cells from neuroblastoma and small cell lung cancer and synergistically potentiate the therapeutic efficacies of Bcl2 antagonists. These findings reveal a PLK1-Fbw7-Myc signaling circuit that underlies tumorigenesis and validate PLK1 inhibitors, alone or with Bcl2 antagonists, as potential effective therapeutics for MYC-overexpressing cancers.
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Affiliation(s)
- Daibiao Xiao
- Zhongnan Hospital of Wuhan University, Wuhan 430071, China; Medical Research Institute, Wuhan University, Wuhan 430071, China
| | - Ming Yue
- Medical Research Institute, Wuhan University, Wuhan 430071, China
| | - Hexiu Su
- Medical Research Institute, Wuhan University, Wuhan 430071, China
| | - Ping Ren
- Medical Research Institute, Wuhan University, Wuhan 430071, China
| | - Jue Jiang
- Medical Research Institute, Wuhan University, Wuhan 430071, China
| | - Feng Li
- Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Yufeng Hu
- Medical Research Institute, Wuhan University, Wuhan 430071, China
| | - Haining Du
- Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Hudan Liu
- Zhongnan Hospital of Wuhan University, Wuhan 430071, China; Medical Research Institute, Wuhan University, Wuhan 430071, China
| | - Guoliang Qing
- Zhongnan Hospital of Wuhan University, Wuhan 430071, China; Medical Research Institute, Wuhan University, Wuhan 430071, China.
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10
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Bengoechea-Alonso MT, Ericsson J. The phosphorylation-dependent regulation of nuclear SREBP1 during mitosis links lipid metabolism and cell growth. Cell Cycle 2016; 15:2753-65. [PMID: 27579997 PMCID: PMC5053579 DOI: 10.1080/15384101.2016.1220456] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2016] [Revised: 07/13/2016] [Accepted: 07/31/2016] [Indexed: 01/02/2023] Open
Abstract
The SREBP transcription factors are major regulators of lipid metabolism. Disturbances in lipid metabolism are at the core of several health issues facing modern society, including cardiovascular disease, obesity and diabetes. In addition, the role of lipid metabolism in cancer cell growth is receiving increased attention. Transcriptionally active SREBP molecules are unstable and rapidly degraded in a phosphorylation-dependent manner by Fbw7, a ubiquitin ligase that targets several cell cycle regulatory proteins for degradation. We have previously demonstrated that active SREBP1 is stabilized during mitosis. We have now delineated the mechanisms involved in the stabilization of SREBP1 in mitotic cells. This process is initiated by the phosphorylation of a specific serine residue in nuclear SREBP1 by the mitotic kinase Cdk1. The phosphorylation of this residue creates a docking site for a separate mitotic kinase, Plk1. Plk1 interacts with nuclear SREBP1 in mitotic cells and phosphorylates a number of residues in the C-terminal domain of the protein, including a threonine residue in close proximity of the Fbw7 docking site in SREBP1. The phosphorylation of these residues by Plk1 blocks the interaction between SREBP1 and Fbw7 and attenuates the Fbw7-dependent degradation of nuclear SREBP1 during cell division. Inactivation of SREBP1 results in a mitotic defect, suggesting that SREBP1 could regulate cell division. We propose that the mitotic phosphorylation and stabilization of nuclear SREBP1 during cell division provides a link between lipid metabolism and cell proliferation. Thus, the current study provides additional support for the emerging hypothesis that SREBP-dependent lipid metabolism may be important for cell growth.
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Affiliation(s)
| | - Johan Ericsson
- University College Dublin, School of Medicine and Medical Science, UCD Conway Institute, Dublin, Ireland
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11
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Chen J, Wu X, Chen S, Chen S, Xiang N, Chen Y, Guo D. Ubiquitin ligase Fbw7 restricts the replication of hepatitis C virus by targeting NS5B for ubiquitination and degradation. Biochem Biophys Res Commun 2016; 470:697-703. [PMID: 26774344 DOI: 10.1016/j.bbrc.2016.01.076] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Accepted: 01/12/2016] [Indexed: 11/16/2022]
Abstract
The nonstructural protein 5B (NS5B) of hepatitis C virus (HCV) is an RNA-dependent RNA polymerase (RdRp) and responsible for replicating the whole HCV genome with help of viral and cellular proteins. However, how cellular factors influence NS5B and, in turn, regulating HCV replication are still poorly defined. The well known tumor suppressor Fbw7, a component of E3 ubiquitin ligase SCF(Fbw7), targets oncoproteins or cellular regulatory proteins for ubiquitin-mediated degradation through a highly conserved binding site called a Cdc4 phosphodegron (CPD). But little is known about whether Fbw7 plays a role in regulation of viral proteins. In this study, we revealed that the conserved CPD is shared by NS5B of almost all genotype of HCV and our data demonstrated that NS5B is a bona fide substrate of Fbw7. Forced expression of Fbw7 promoted the ubiquination of NS5B and negatively regulated its turnover in the proteasome-dependent manner. We further revealed the interaction between NS5B and Fbw7, which resulted in the relocation of Fbw7 from nucleus to cytoplasm. During HCV replication, ectopic expression of Fbw7 could strongly down-regulate NS5B level and consequently inhibited the virus replication. When endogenous Fbw7 was knocked down, both NS5B protein abundance and HCV replication were remarkably up-regulated. The results provide more insights into the interplay of HCV and cellular factors and shed light on molecular mechanisms of HCV replication and pathogenesis.
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Affiliation(s)
- Jun Chen
- State Key Laboratory of Virology and Modern Virology Research Center, College of Life Sciences, Wuhan University, Wuhan, Hubei 430072, PR China
| | - Xiaoyun Wu
- Bio-Thera Solutions, Ltd. Co., Enterprise Accelerator A6-5fl, 11 Kaiyuan Rd, Science City, Guangzhou 510530, PR China
| | - Shiyou Chen
- State Key Laboratory of Virology and Modern Virology Research Center, College of Life Sciences, Wuhan University, Wuhan, Hubei 430072, PR China
| | - Shuliang Chen
- State Key Laboratory of Virology and Modern Virology Research Center, College of Life Sciences, Wuhan University, Wuhan, Hubei 430072, PR China
| | - Nian Xiang
- State Key Laboratory of Virology and Modern Virology Research Center, College of Life Sciences, Wuhan University, Wuhan, Hubei 430072, PR China
| | - Yu Chen
- State Key Laboratory of Virology and Modern Virology Research Center, College of Life Sciences, Wuhan University, Wuhan, Hubei 430072, PR China
| | - Deyin Guo
- State Key Laboratory of Virology and Modern Virology Research Center, College of Life Sciences, Wuhan University, Wuhan, Hubei 430072, PR China; School of Basic Medical Sciences, Wuhan University, Wuhan, Hubei 430072, PR China.
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12
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Kumar Y, Kapoor I, Khan K, Thacker G, Khan MP, Shukla N, Kanaujiya JK, Sanyal S, Chattopadhyay N, Trivedi AK. E3 Ubiquitin Ligase Fbw7 Negatively Regulates Osteoblast Differentiation by Targeting Runx2 for Degradation. J Biol Chem 2015; 290:30975-87. [PMID: 26542806 DOI: 10.1074/jbc.m115.669531] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Indexed: 11/06/2022] Open
Abstract
Runx2, a master regulator of osteoblast differentiation, is tightly regulated at both transcriptional and post-translational levels. Post-translational modifications such as phosphorylation and ubiquitination have differential effects on Runx2 functions. Here, we show that the reduced expression and functions of Runx2 upon its phosphorylation by GSK3β are mediated by its ubiquitin-mediated degradation through E3 ubiquitin ligase Fbw7α. Fbw7α through its WD domain interacts with Runx2 both in a heterologous (HEK293T cells) system as well as in osteoblasts. GSK3β was also present in the same complex as determined by co-immunoprecipitation. Furthermore, overexpression of either Fbw7α or GSK3β was sufficient to down-regulate endogenous Runx2 expression and function; however, both failed to inhibit endogenous Runx2 when either of them was depleted in osteoblasts. Fbw7α-mediated inhibition of Runx2 expression also led to reduced Runx2 transactivation and osteoblast differentiation. In contrast, inhibition of Fbw7α restored Runx2 levels and promoted osteoblast differentiation. We also observed reciprocal expression levels of Runx2 and Fbw7α in models of bone loss such as lactating (physiological bone loss condition) and ovariectomized (induction of surgical menopause) animals that show reduced Runx2 and enhanced Fbw7α, whereas this was reversed in the estrogen-treated ovariectomized animals. In addition, methylprednisolone (a synthetic glucocorticoid) treatment to neonatal rats showed a temporal decrease in Runx2 with a reciprocal increase in Fbw7 in their calvarium. Taken together, these data demonstrate that Fbw7α negatively regulates osteogenesis by targeting Runx2 for ubiquitin-mediated degradation in a GSK3β-dependent manner and thus provides a plausible explanation for GSK3β-mediated bone loss as described before.
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Affiliation(s)
- Yogesh Kumar
- From the Biochemistry Division, CSIR-Central Drug Research Institute (CSIR-CDRI), Sector-10, Jankipuram Extension, Lucknow, 226031 Uttar Pradesh and
| | - Isha Kapoor
- From the Biochemistry Division, CSIR-Central Drug Research Institute (CSIR-CDRI), Sector-10, Jankipuram Extension, Lucknow, 226031 Uttar Pradesh and
| | - Kainat Khan
- the Division of Endocrinology and Center for Research in Anabolic Skeletal Targets in Health and Illness (ASTHI), CSIR-Central Drug Research Institute (CSIR-CDRI), Sector-10, Jankipuram Extension, Lucknow, 226031 Uttar Pradesh, India
| | - Gatha Thacker
- From the Biochemistry Division, CSIR-Central Drug Research Institute (CSIR-CDRI), Sector-10, Jankipuram Extension, Lucknow, 226031 Uttar Pradesh and
| | - Mohd Parvez Khan
- the Division of Endocrinology and Center for Research in Anabolic Skeletal Targets in Health and Illness (ASTHI), CSIR-Central Drug Research Institute (CSIR-CDRI), Sector-10, Jankipuram Extension, Lucknow, 226031 Uttar Pradesh, India
| | - Nidhi Shukla
- From the Biochemistry Division, CSIR-Central Drug Research Institute (CSIR-CDRI), Sector-10, Jankipuram Extension, Lucknow, 226031 Uttar Pradesh and
| | - Jitendra Kumar Kanaujiya
- From the Biochemistry Division, CSIR-Central Drug Research Institute (CSIR-CDRI), Sector-10, Jankipuram Extension, Lucknow, 226031 Uttar Pradesh and
| | - Sabyasachi Sanyal
- From the Biochemistry Division, CSIR-Central Drug Research Institute (CSIR-CDRI), Sector-10, Jankipuram Extension, Lucknow, 226031 Uttar Pradesh and
| | - Naibedya Chattopadhyay
- the Division of Endocrinology and Center for Research in Anabolic Skeletal Targets in Health and Illness (ASTHI), CSIR-Central Drug Research Institute (CSIR-CDRI), Sector-10, Jankipuram Extension, Lucknow, 226031 Uttar Pradesh, India
| | - Arun Kumar Trivedi
- From the Biochemistry Division, CSIR-Central Drug Research Institute (CSIR-CDRI), Sector-10, Jankipuram Extension, Lucknow, 226031 Uttar Pradesh and
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13
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Abstract
Cancer stem cells (CSCs) are undifferentiated cancer cells with a high tumorigenic activity, the ability to undergo self-renewal, and a multilineage differentiation potential. Cancer stem cells are responsible for the development of tumor cell heterogeneity, a key feature for resistance to anticancer treatments including conventional chemotherapy, radiation therapy, and molecularly targeted therapy. Furthermore, minimal residual disease, the major cause of cancer recurrence and metastasis, is enriched in CSCs. Cancer stem cells also possess the property of "robustness", which encompasses several characteristics including a slow cell cycle, the ability to detoxify or mediate the efflux of cytotoxic agents, resistance to oxidative stress, and a rapid response to DNA damage, all of which contribute to the development of therapeutic resistance. The identification of mechanisms underlying such characteristics and the development of novel approaches to target them will be required for the therapeutic elimination of CSCs and the complete eradication of tumors. In this review, we focus on two prospective therapeutic approaches that target CSCs with the aim of disrupting their quiescence or redox defense capability.
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Affiliation(s)
- Go J Yoshida
- Department of Pathological Cell Biology, Medical Research Institute, Tokyo Medical and Dental University, Tokyo, Japan.,Japan Society for the Promotion of Science, Tokyo, Japan
| | - Hideyuki Saya
- Division of Gene Regulation, Institute for Advanced Medical Research, School of Medicine, Keio University, Tokyo, Japan
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14
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Abstract
The F-box protein Fbw7 targets for degradation critical cellular regulators, thereby controlling essential processes in cellular homeostasis, including cell cycle, differentiation and apoptosis. Most Fbw7 substrates are strongly associated with tumorigenesis and Fbw7 can either suppress or promote tumor development in mouse models. Fbw7 activity is controlled at different levels, resulting in specific and tunable regulation of the abundance and activity of its substrates. Here we highlight recent studies on the role of Fbw7 in controlling tumorigenesis and on the mechanisms that modulate Fbw7 function.
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Affiliation(s)
- Wenshan Xu
- Department of Radiation Oncology and Comprehensive Cancer Center Mainfranken, University Hospital Würzburg, Versbacher Str. 5, 97078 Würzburg, Germany
| | - Lyudmyla Taranets
- Department of Radiation Oncology and Comprehensive Cancer Center Mainfranken, University Hospital Würzburg, Versbacher Str. 5, 97078 Würzburg, Germany
| | - Nikita Popov
- Department of Radiation Oncology and Comprehensive Cancer Center Mainfranken, University Hospital Würzburg, Versbacher Str. 5, 97078 Würzburg, Germany.
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15
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Cremona CA, Sancho R, Diefenbacher ME, Behrens A. Fbw7 and its counteracting forces in stem cells and cancer: Oncoproteins in the balance. Semin Cancer Biol 2016; 36:52-61. [PMID: 26410034 DOI: 10.1016/j.semcancer.2015.09.006] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Accepted: 09/10/2015] [Indexed: 12/14/2022]
Abstract
Fbw7 is well characterised as a stem cell regulator and tumour suppressor, powerfully positioned to control proliferation, differentiation and apoptosis by targeting key transcription factors for ubiquitination and destruction. Evidence in support of these roles continues to accumulate from in vitro studies, mouse models and human patient data. Here we summarise the latest of these findings, highlighting the tumour-suppressive role of Fbw7 in multiple tissues, and the rare circumstances where Fbw7 activity can be oncogenic. We discuss mechanisms that regulate ubiquitination by Fbw7, including ubiquitin-specific proteases such as USP28 that counteract Fbw7 activity and thereby stabilise oncoproteins. Deubiquitination of key Fbw7 substrates to prevent their destruction is beginning to be appreciated as an important pro-tumourigenic mechanism. As the ubiquitin-proteasome system represents a largely untapped field for drug development, the interplay between Fbw7 and its counterpart deubiquitinating enzymes in tumours is likely to attract increasing interest and influence future treatment strategies.
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16
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Baek HJ, Yoon JH, Ann EJ, Kim MY, Ahn JS, Kim SH, Jo EH, Lee HJ, Park HS. Alpha-synuclein negatively regulates Notch1 intracellular domain protein stability through promoting interaction with Fbw7. Neurosci Lett 2015; 600:6-11. [PMID: 26033182 DOI: 10.1016/j.neulet.2015.05.053] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Revised: 05/19/2015] [Accepted: 05/22/2015] [Indexed: 01/27/2023]
Abstract
Notch signaling pathway is well known that it is involved in regulating cell fate, proliferation and homeostasis. In this study, we show a novel function of alpha-synuclein (SNCA) to promote degradation of Notch1 intracellular domain (Notch1-IC) through Fbw7, ubiquitin E3 ligase. We identified that SNCA inhibits Notch1 transcription activity and diminishes the interaction between Notch1-IC and RBP-Jk. We also found decrease of Notch1-IC protein stability by exogenous and endogenous SNCA through proteasomal pathway, not through lysosomal pathway. And, we found that SNCA promotes interaction between Notch1-IC and Fbw7. Furthermore, SNCA directly interacts with Fbw7. SNCA increases ubiquitination of Notch-IC by Fbw7 through interaction with Fbw7. Together, these results suggest that SNCA is a novel regulator of Notch1-IC transcriptional activity with acting as an enhancer of the interaction of Notch1-IC and Fbw7 with increasing degradation of Notch1-IC.
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Affiliation(s)
- Hyeong-Jin Baek
- Hormone Research Center, School of Biological Sciences and Technology, Chonnam National University, Gwangju, Republic of Korea
| | - Ji-Hye Yoon
- Hormone Research Center, School of Biological Sciences and Technology, Chonnam National University, Gwangju, Republic of Korea
| | - Eun-Jung Ann
- Hormone Research Center, School of Biological Sciences and Technology, Chonnam National University, Gwangju, Republic of Korea
| | - Mi-Yeon Kim
- Hormone Research Center, School of Biological Sciences and Technology, Chonnam National University, Gwangju, Republic of Korea
| | - Ji-Seon Ahn
- Hormone Research Center, School of Biological Sciences and Technology, Chonnam National University, Gwangju, Republic of Korea
| | - Seol-Hee Kim
- Hormone Research Center, School of Biological Sciences and Technology, Chonnam National University, Gwangju, Republic of Korea
| | - Eun-Hye Jo
- Hormone Research Center, School of Biological Sciences and Technology, Chonnam National University, Gwangju, Republic of Korea
| | - Hye-Jin Lee
- Hormone Research Center, School of Biological Sciences and Technology, Chonnam National University, Gwangju, Republic of Korea
| | - Hee-Sae Park
- Hormone Research Center, School of Biological Sciences and Technology, Chonnam National University, Gwangju, Republic of Korea.
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17
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Nakajima T, Kitagawa K, Ohhata T, Sakai S, Uchida C, Shibata K, Minegishi N, Yumimoto K, Nakayama KI, Masumoto K, Katou F, Niida H, Kitagawa M. Regulation of GATA-binding protein 2 levels via ubiquitin-dependent degradation by Fbw7: involvement of cyclin B-cyclin-dependent kinase 1-mediated phosphorylation of THR176 in GATA-binding protein 2. J Biol Chem 2015; 290:10368-81. [PMID: 25670854 DOI: 10.1074/jbc.m114.613018] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2014] [Indexed: 11/06/2022] Open
Abstract
A GATA family transcription factor, GATA-binding protein 2 (GATA2), participates in cell growth and differentiation of various cells, such as hematopoietic stem cells. Although its expression level is controlled by transcriptional induction and proteolytic degradation, the responsible E3 ligase has not been identified. Here, we demonstrate that F-box/WD repeat-containing protein 7 (Fbw7/Fbxw7), a component of Skp1, Cullin 1, F-box-containing complex (SCF)-type E3 ligase, is an E3 ligase for GATA2. GATA2 contains a cell division control protein 4 (Cdc4) phosphodegron (CPD), a consensus motif for ubiquitylation by Fbw7, which includes Thr(176). Ectopic expression of Fbw7 destabilized GATA2 and promoted its proteasomal degradation. Substitution of threonine 176 to alanine in GATA2 inhibited binding with Fbw7, and the ubiquitylation and degradation of GATA2 by Fbw7 was suppressed. The CPD kinase, which mediates the phosphorylation of Thr(176), was cyclin B-cyclin-dependent kinase 1 (CDK1). Moreover, depletion of endogenous Fbw7 stabilized endogenous GATA2 in K562 cells. Conditional Fbw7 depletion in mice increased GATA2 levels in hematopoietic stem cells and myeloid progenitors at the early stage. Increased GATA2 levels in Fbw7-conditional knock-out mice were correlated with a decrease in a c-Kit high expressing population of myeloid progenitor cells. Our results suggest that Fbw7 is a bona fide E3 ubiquitin ligase for GATA2 in vivo.
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Affiliation(s)
- Tomomi Nakajima
- From the Departments of Molecular Biology and Oral and Maxillofacial Surgery and
| | | | | | | | - Chiharu Uchida
- the Research Equipment Center, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu, Shizuoka 431-3192, Japan
| | - Kiyoshi Shibata
- the Research Equipment Center, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu, Shizuoka 431-3192, Japan
| | - Naoko Minegishi
- the Department of Biobank Life Science, Tohoku University School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi 980-8573, Japan, and
| | - Kanae Yumimoto
- the Department of Molecular and Cellular Biology, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Keiichi I Nakayama
- the Department of Molecular and Cellular Biology, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
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18
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Abstract
The Usp28 deubiquitinase antagonizes Fbw7-mediated turnover of multiple oncoproteins, including Myc, Jun, and Notch, and promotes tumorigenesis in the intestine. Our recent study reveals that Usp28 also counteracts autocatalytic ubiquitination of Fbw7, suggesting a complex role for Usp28 in the regulation of Fbw7 activity and tumor development.
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Affiliation(s)
- Lyudmyla Taranets
- Comprehensive Cancer Center Mainfranken and Department of Radiation Oncology; University Hospital Würzburg ; Würzburg, Germany
| | - Jing Zhu
- Comprehensive Cancer Center Mainfranken and Department of Radiation Oncology; University Hospital Würzburg ; Würzburg, Germany
| | - Wenshan Xu
- Comprehensive Cancer Center Mainfranken and Department of Radiation Oncology; University Hospital Würzburg ; Würzburg, Germany
| | - Nikita Popov
- Comprehensive Cancer Center Mainfranken and Department of Radiation Oncology; University Hospital Würzburg ; Würzburg, Germany
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19
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Welcker M, Larimore EA, Swanger J, Bengoechea-Alonso MT, Grim JE, Ericsson J, Zheng N, Clurman BE. Fbw7 dimerization determines the specificity and robustness of substrate degradation. Genes Dev 2014; 27:2531-6. [PMID: 24298052 PMCID: PMC3861666 DOI: 10.1101/gad.229195.113] [Citation(s) in RCA: 75] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The Fbw7 tumor suppressor targets a broad network of proteins for ubiquitylation. Here we show critical functions for Fbw7 dimerization in regulating the specificity and robustness of degradation. Dimerization enables Fbw7 to target substrates through concerted binding to two suboptimal and independent recognition sites. Accordingly, an endogenous dimerization-deficient Fbw7 mutation stabilizes suboptimal substrates. Dimerization increases Fbw7's robustness by preserving its function in the setting of mutations that disable Fbw7 monomers, thereby buffering against pathogenic mutations. Finally, dimerization regulates Fbw7 stability, and this likely involves Fbw7 trans-autoubiquitylation. Our study reveals novel functions of Fbw7 dimerization and an unanticipated complexity in substrate degradation.
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20
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Lochab S, Pal P, Kapoor I, Kanaujiya JK, Sanyal S, Behre G, Trivedi AK. E3 ubiquitin ligase Fbw7 negatively regulates granulocytic differentiation by targeting G-CSFR for degradation. Biochim Biophys Acta 2013; 1833:2639-2652. [PMID: 23820376 DOI: 10.1016/j.bbamcr.2013.06.018] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2013] [Revised: 06/10/2013] [Accepted: 06/21/2013] [Indexed: 11/30/2022]
Abstract
Tight control between activation and attenuation of granulocyte colony stimulating factor receptor (G-CSFR) signaling is essential to regulate survival, proliferation and differentiation of myeloid progenitor cells. Previous studies demonstrated negative regulation of G-CSFR through endosomal-lysosomal routing and ubiquitin-proteasome mediated degradation. However, very few E3 ubiquitin ligases are known to target G-CSFR for ubiquitin-proteasome pathway. Here we identified F-box and WD repeat domain-containing 7 (Fbw7), a substrate recognizing component of Skp-Cullin-F box (SCF) E3 ubiquitin Ligase physically associates with G-CSFR and promotes its ubiquitin-mediated proteasomal degradation. Our data shows that Fbw7 also interacts with and degrades G-CSFR-T718 (a truncated mutant of G-CSFR found in severe congenital neutropenia/acute myeloid leukemia (SCN/AML patients)) though at a quite slower rate compared to G-CSFR. We further show that glycogen synthase kinase 3 beta (GSK3β), like Fbw7 also targets G-CSFR and G-CSFR-T718 for degradation; however, Fbw7 and GSK3β are interdependent in targeting G-CSFR/G-CSFR-T718 for degradation because they are unable to degrade G-CSFR individually when either of them is knocked down. We further show that Fbw7 mediated downregulation of G-CSFR inhibits signal transducer and activator of transcription 3 (STAT3) phosphorylation which is required for G-CSF dependent granulocytic differentiation. In addition, our data also shows that inhibition of Fbw7 restores G-CSFR signaling leading to enhanced STAT3 activity resulting in massive granulocytic differentiation. These data indicate that Fbw7 together with GSK3β negatively regulates G-CSFR expression and its downstream signaling.
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Affiliation(s)
- Savita Lochab
- Drug Target Discovery and Development Division, CSIR-Central Drug Research Institute (CSIR-CDRI), Sector-10, Jankipuram Extension, Lucknow, 226031 UP, India
| | - Pooja Pal
- Drug Target Discovery and Development Division, CSIR-Central Drug Research Institute (CSIR-CDRI), Sector-10, Jankipuram Extension, Lucknow, 226031 UP, India
| | - Isha Kapoor
- Drug Target Discovery and Development Division, CSIR-Central Drug Research Institute (CSIR-CDRI), Sector-10, Jankipuram Extension, Lucknow, 226031 UP, India
| | - Jitendra Kumar Kanaujiya
- Drug Target Discovery and Development Division, CSIR-Central Drug Research Institute (CSIR-CDRI), Sector-10, Jankipuram Extension, Lucknow, 226031 UP, India
| | - Sabyasachi Sanyal
- Drug Target Discovery and Development Division, CSIR-Central Drug Research Institute (CSIR-CDRI), Sector-10, Jankipuram Extension, Lucknow, 226031 UP, India
| | - Gerhard Behre
- Division of Hematology and Oncology, University Hospital of Leipzig, Johannissallee 32A, 04103 Leipzig, Germany
| | - Arun Kumar Trivedi
- Drug Target Discovery and Development Division, CSIR-Central Drug Research Institute (CSIR-CDRI), Sector-10, Jankipuram Extension, Lucknow, 226031 UP, India.
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21
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Chandra S, Priyadarshini R, Madhavan V, Tikoo S, Hussain M, Mudgal R, Modi P, Srivastava V, Sengupta S. Enhancement of c-Myc degradation by BLM helicase leads to delayed tumor initiation. J Cell Sci 2013; 126:3782-95. [PMID: 23750012 DOI: 10.1242/jcs.124719] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The spectrum of tumors that arise owing to the overexpression of c-Myc and loss of BLM is very similar. Hence, it was hypothesized that the presence of BLM negatively regulates c-Myc functions. By using multiple isogenic cell lines, we observed that the decrease of endogenous c-Myc levels that occurs in the presence of BLM is reversed when the cells are treated with proteasome inhibitors, indicating that BLM enhances c-Myc turnover. Whereas the N-terminal region of BLM interacts with c-Myc, the rest of the helicase interacts with the c-Myc E3 ligase Fbw7. The two BLM domains act as 'clamp and/or adaptor', enhancing the binding of c-Myc to Fbw7. BLM promotes Fbw7-dependent K48-linked c-Myc ubiquitylation and its subsequent degradation in a helicase-independent manner. A subset of BLM-regulated genes that are also targets of c-Myc were determined and validated at both RNA and protein levels. To obtain an in vivo validation of the effect of BLM on c-Myc-mediated tumor initiation, isogenic cells from colon cancer cells that either do or do not express BLM had been manipulated to block c-Myc expression in a controlled manner. By using these cell lines, the metastatic potential and rate of initiation of tumors in nude mice were determined. The presence of BLM decreases c-Myc-mediated invasiveness and delays tumor initiation in a mouse xenograft model. Consequently, in tumors that express BLM but not c-Myc, we observed a decreased ratio of proliferation to apoptosis together with a suppressed expression of the angiogenesis marker CD31. Hence, partly owing to its regulation of c-Myc stability, BLM acts as a 'caretaker tumor suppressor'.
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Affiliation(s)
- Suruchika Chandra
- National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi 110067, India
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22
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Biswas M, Kwong EK, Park E, Nagra P, Chan JY. Glycogen synthase kinase 3 regulates expression of nuclear factor-erythroid-2 related transcription factor-1 (Nrf1) and inhibits pro-survival function of Nrf1. Exp Cell Res 2013; 319:1922-1931. [PMID: 23623971 DOI: 10.1016/j.yexcr.2013.04.013] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2012] [Revised: 03/29/2013] [Accepted: 04/16/2013] [Indexed: 12/30/2022]
Abstract
Nuclear factor E2-related factor-1 (Nrf1) is a basic leucine zipper transcription factor that is known to regulate antioxidant and cytoprotective gene expression. It was recently shown that Nrf1 is regulated by SCF-Fbw7 ubiquitin ligase. However our knowledge of upstream signals that targets Nrf1 for degradation by the UPS is not known. We report here that Nrf1 expression is negatively regulated by glycogen synthase kinase 3 (GSK3) in Fbw7-dependent manner. We show that GSK3 interacts with Nrf1 and phosphorylates the Cdc4 phosphodegron domain (CPD) in Nrf1. Mutation of serine residue in the CPD of Nrf1 to alanine (S350A), blocks Nrf1 from phosphorylation by GSK3, and stabilizes Nrf1. Knockdown of Nrf1 and expression of a constitutively active form of GSK3 results in increased apoptosis in neuronal cells in response to ER stress, while expression of the GSK3 phosphorylation resistant S350A-Nrf1 attenuates apoptotic cell death. Together these data suggest that GSK3 regulates Nrf1 expression and cell survival function in response to stress activation.
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Affiliation(s)
- Madhurima Biswas
- Department of Laboratory Medicine and Pathology, University of California, Irvine, D440 Medical Science 1, Irvine, CA 92697, USA
| | - Erick K Kwong
- Department of Laboratory Medicine and Pathology, University of California, Irvine, D440 Medical Science 1, Irvine, CA 92697, USA
| | - Eujean Park
- Department of Laboratory Medicine and Pathology, University of California, Irvine, D440 Medical Science 1, Irvine, CA 92697, USA
| | - Parminder Nagra
- Department of Laboratory Medicine and Pathology, University of California, Irvine, D440 Medical Science 1, Irvine, CA 92697, USA
| | - Jefferson Y Chan
- Department of Laboratory Medicine and Pathology, University of California, Irvine, D440 Medical Science 1, Irvine, CA 92697, USA.
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23
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Caldon CE, Sergio CM, Sutherland RL, Musgrove EA. Differences in degradation lead to asynchronous expression of cyclin E1 and cyclin E2 in cancer cells. Cell Cycle 2013; 12:596-605. [PMID: 23324394 PMCID: PMC3594260 DOI: 10.4161/cc.23409] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Cyclin E1 is expressed at the G 1/S phase transition of the cell cycle to drive the initiation of DNA replication and is degraded during S/G2M. Deregulation of its periodic degradation is observed in cancer and is associated with increased proliferation and genomic instability. We identify that in cancer cells, unlike normal cells, the closely related protein cyclin E2 is expressed predominantly in S phase, concurrent with DNA replication. This occurs at least in part because the ubiquitin ligase component that is responsible for cyclin E1 downregulation in S phase, Fbw7, fails to effectively target cyclin E2 for proteosomal degradation. The distinct cell cycle expression of the two E-type cyclins in cancer cells has implications for their roles in genomic instability and proliferation and may explain their associations with different signatures of disease.
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Affiliation(s)
- C Elizabeth Caldon
- The Kinghorn Cancer Centre and Cancer Research Program, Garvan Institute of Medical Research, Sydney, NSW, Australia.
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