The ubiquitin-proteasome system is a key mechanism that plants use to generate adaptive responses in coping with various en- vironmental stresses. Cullin-RING （CRL） complexes represent a predominant group of ubiquit...The ubiquitin-proteasome system is a key mechanism that plants use to generate adaptive responses in coping with various en- vironmental stresses. Cullin-RING （CRL） complexes represent a predominant group of ubiquitin E3 ligases in this system. In this review, we focus on the CRL E3s that have been implicated in abiotic stress signaling pathways in Arabidopsis. By comparing and analyzing these cases, we hope to gain a better understanding on how CRL complexes work under various settings in an attempt to decipher the clues about the regulatory mechanism of CRL E3s.展开更多
The COP9 signalosome(CSN)is a highly conserved protein complex composed of 8 subunits(CSN1 to CSN8).The individual subunits of the CSN play essential roles in cell proliferation,tumorigenesis,cell cycle regulation,DNA...The COP9 signalosome(CSN)is a highly conserved protein complex composed of 8 subunits(CSN1 to CSN8).The individual subunits of the CSN play essential roles in cell proliferation,tumorigenesis,cell cycle regulation,DNA damage repair,angiogenesis,and microenvironmental homeostasis.The CSN complex has an intrinsic metalloprotease that removes the ubiquitin-like activator NEDD8 from cullin-RING ligases(CRLs).Binding of neddylated CRLs to CSN is sensed by CSN4 and communicated to CSN5 with the assistance of CSN6,thus leading to the activation of deneddylase.Therefore,CSN is a crucial regulator at the intersection between neddylation and ubiquitination in cancer progression.Here,we summarize current understanding of the roles of individual CSN subunits in cancer progression.Furthermore,we explain how the CSN affects tumorigenesis through regulating transcription factors and the cell cycle.Finally,we discuss individual CSN subunits as potential therapeutic targets to provide new directions and strategies for cancer therapy.展开更多
The mechanism regulating proteasomal activity under proteotoxic stress conditions remains unclear.Here,we showed that arsenite-induced proteotoxic stress resulted in upregulation of Arabidopsis homologous PUB22 and PU...The mechanism regulating proteasomal activity under proteotoxic stress conditions remains unclear.Here,we showed that arsenite-induced proteotoxic stress resulted in upregulation of Arabidopsis homologous PUB22 and PUB23 U-boxE3 ubiquitin ligases and that pub22 pub23 double mutants displayed arsenite-insensitive seed germination and root growth phenotypes.PUB22/PUB23 downregulated 26 S proteasome activity by promoting the dissociation of the 19 S regulatory particle from the holo-proteasome complex,resulting in intracellular accumulation of UbG76 VGFP,an artificial substrate of the proteasome complex,and insoluble poly-ubiquitinated proteins.These results suggest that PUB22/PUB23 play a critical role in arsenite-induced proteotoxic stress response via negative regulation of 26 S proteasome integrity.展开更多
MAP kinase-interacting kinase-2 (Mnk2) is one of the downstream kinasesactivated by MAP kinases. It phosphorylates the eukaryotic initiation factor 4E (elF4E), althoughthe role of elF4E phosphorylation and the role of...MAP kinase-interacting kinase-2 (Mnk2) is one of the downstream kinasesactivated by MAP kinases. It phosphorylates the eukaryotic initiation factor 4E (elF4E), althoughthe role of elF4E phosphorylation and the role of Mnk2 in the process of proteintranslation are notwell understood. Except for elF4E, other physiological substrates of Mnk2 are still unidentified. Tolook for these unidentified substrates and to reveal the physiological function of Mnk2, weperformed a yeast two-hybrid screening with Mnk2 as the bait. The results demonstrated Mnk2 couldinteract with VHL (von Hippel-Lindau tumor suppressor), Rbx1 (ring-box1) and Cul2 (Cullin2) proteinsin yeast cells. Furthermore, we validated the interaction between Mnk2 and VHL proteins inmammalian cells by co-immunoprecipitation analysis. Because the three proteins VHL, Rbx1 and Cul2are all components of the CBC^(VHL) ubiquitin ligase E3 complex, it has been shown that Mnk2 caninteract with CBC^(VHL) complex, and is probably one of the newsubstrates of the CBC^(VHL) complex.Furthermore, during the interaction of Mnk2 with von Hippel-Lindau (VHL) tumor suppressor- bindingprotein 1 (VBP1), it appears that Mnk2 also joins to modulate cell shape as VBP1 plays an importantrole in the process of the maturation of the cytoskeleton and in the process of morphogenesis.展开更多
Objective:The hyperactivated neddylation pathway plays an important role in tumorigenesis and is emerging as a promising anticancer target.We aimed to study whether NEDD8(neural precursor cell expressed,developmentall...Objective:The hyperactivated neddylation pathway plays an important role in tumorigenesis and is emerging as a promising anticancer target.We aimed to study whether NEDD8(neural precursor cell expressed,developmentally down-regulated 8)might serve as a therapeutic target in esophageal squamous cell carcinoma(ESCC).Methods:The clinical relevance of NEDD8 expression was evaluated by using The Cancer Genome Atlas(TCGA)database and tissue arrays.NEDD8-knockdown ESCC cells generated with the CRISPR/Cas9 system were used to explore the anticancer effects and mechanisms.Quantitative proteomic analysis was used to examine the variations in NEDD8 knockdown-induced biological pathways.The cell cycle and apoptosis were assessed with fluorescence activated cell sorting.A subcutaneous-transplantation mouse tumor model was established to investigate the anticancer potential of NEDD8 silencing in vivo.Results:NEDD8 was upregulated at both the mRNA and protein expression levels in ESCC,and NEDD8 overexpression was associated with poorer overall patient survival(mRNA level:P=0.028,protein level:P=0.026,log-rank test).Downregulation of NEDD8 significantly suppressed tumor growth both in vitro and in vivo.Quantitative proteomic analysis revealed that downregulation of NEDD8 induced cell cycle arrest,DNA damage,and apoptosis in ESCC cells.Mechanistic studies demonstrated that NEDD8 knockdown led to the accumulation of cullin-RING E3 ubiquitin ligases(CRLs)substrates through inactivation of CRLs,thus suppressing the malignant phenotype by inducing cell cycle arrest and apoptosis in ESCC.Rescue experiments demonstrated that the induction of apoptosis after NEDD8 silencing was attenuated by DR5 knockdown.Conclusions:Our study elucidated the anti-ESCC effects and underlying mechanisms of NEDD8 knockdown,and validated NEDD8 as a potential target for ESCC therapy.展开更多
Obesity is a serious health problem of our time. Dysfunction of adipogenesis, the differentiation of adipocytes, is a hallmark of obesity. Therefore here we investigate the role of the COP9 signalosome and of CHOP in ...Obesity is a serious health problem of our time. Dysfunction of adipogenesis, the differentiation of adipocytes, is a hallmark of obesity. Therefore here we investigate the role of the COP9 signalosome and of CHOP in the differentiation of LiSa-2 preadipocytes.展开更多
SAG(Sensitive to Apoptosis Gene),also known as RBX2(RING box protein 2),ROC2(Regulator of Cullins 2),or RNF7(RING Finger Protein 7),was originally cloned in our laboratory as a redox inducible antioxi-dant protein and...SAG(Sensitive to Apoptosis Gene),also known as RBX2(RING box protein 2),ROC2(Regulator of Cullins 2),or RNF7(RING Finger Protein 7),was originally cloned in our laboratory as a redox inducible antioxi-dant protein and later characterized as the second member of the RBX/ROC RING component of the SCF(SKP1-CUL-F-box Proteins)E3 ubiquitin ligase.When acting alone,SAG scavenges oxygen radicals by forming inter-and intra-molecular disulfide bonds,whereas by forming a complex with other components of the SCF E3 ligase,SAG promotes ubiquitination and degradation of a number of protein substrates,includ-ing c-JUN,DEPTOR,HIF-1α,IκBα,NF1,NOXA,p27,and procaspase-3,thus regulating various signaling path-ways and biological processes.Specifically,SAG pro-tects cells from apoptosis,confers radioresistance,and plays an essential and non-redundant role in mouse embryogenesis and vasculogenesis.Furthermore,stress-inducible SAG is overexpressed in a number of human cancers and SAG overexpression correlates with poor patient prognosis.Finally,SAG transgenic expression in epidermis causes an early stage inhibi-tion,but later stage promotion,of skin tumorigenesis triggered by DMBA/TPA.Given its major role in pro-moting targeted degradation of tumor suppressive proteins,leading to apoptosis suppression and accel-erated tumorigenesis,SAG E3 ligase appears to be an attractive anticancer target.展开更多
基金supported by the "New Century Excellent Talents"program of the Ministry of Education, China [NCET-10-0153]the China Postdoctoral Visiting-Scholar Fellowship (201104519+4 种基金20100481042)the Ministry of Environmental Protection of the PRC (2011467032)a National Institutes of Health grant (GM47850)the National Science Foundation (NSF) Plant Genome Program (DBI0922604)the NSF 2010 program (MCB-0929100)
文摘The ubiquitin-proteasome system is a key mechanism that plants use to generate adaptive responses in coping with various en- vironmental stresses. Cullin-RING （CRL） complexes represent a predominant group of ubiquitin E3 ligases in this system. In this review, we focus on the CRL E3s that have been implicated in abiotic stress signaling pathways in Arabidopsis. By comparing and analyzing these cases, we hope to gain a better understanding on how CRL complexes work under various settings in an attempt to decipher the clues about the regulatory mechanism of CRL E3s.
基金This work was supported by the National Natural Science Foundation of China(Grant No.81872080)Jiangsu Provincial Medical Talent(Grant No.ZDRCA 2016055)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD).
文摘The COP9 signalosome(CSN)is a highly conserved protein complex composed of 8 subunits(CSN1 to CSN8).The individual subunits of the CSN play essential roles in cell proliferation,tumorigenesis,cell cycle regulation,DNA damage repair,angiogenesis,and microenvironmental homeostasis.The CSN complex has an intrinsic metalloprotease that removes the ubiquitin-like activator NEDD8 from cullin-RING ligases(CRLs).Binding of neddylated CRLs to CSN is sensed by CSN4 and communicated to CSN5 with the assistance of CSN6,thus leading to the activation of deneddylase.Therefore,CSN is a crucial regulator at the intersection between neddylation and ubiquitination in cancer progression.Here,we summarize current understanding of the roles of individual CSN subunits in cancer progression.Furthermore,we explain how the CSN affects tumorigenesis through regulating transcription factors and the cell cycle.Finally,we discuss individual CSN subunits as potential therapeutic targets to provide new directions and strategies for cancer therapy.
基金supported by grants from the National Research Foundation(Mid-Career Researcher Program Project No.2017R1A2B2006750 and Basic Science Research Program Project No.2018R1A6A1A03025607),Republic of Korea,to Woo T.Kim。
文摘The mechanism regulating proteasomal activity under proteotoxic stress conditions remains unclear.Here,we showed that arsenite-induced proteotoxic stress resulted in upregulation of Arabidopsis homologous PUB22 and PUB23 U-boxE3 ubiquitin ligases and that pub22 pub23 double mutants displayed arsenite-insensitive seed germination and root growth phenotypes.PUB22/PUB23 downregulated 26 S proteasome activity by promoting the dissociation of the 19 S regulatory particle from the holo-proteasome complex,resulting in intracellular accumulation of UbG76 VGFP,an artificial substrate of the proteasome complex,and insoluble poly-ubiquitinated proteins.These results suggest that PUB22/PUB23 play a critical role in arsenite-induced proteotoxic stress response via negative regulation of 26 S proteasome integrity.
文摘骨骼肌功能障碍是慢性阻塞性肺疾病(chronic obstructive pulmonary disease,COPD)的重要组成部分,它包括呼吸肌以及外周非呼吸肌的功能下降,具体表现为:肌肉体积减小,运动强度下降,运动耐力下降。骨骼肌功能障碍严重影响到COPD患者的生活质量及疾病的预后。但是目前COPD的骨骼肌功能障碍发生的具体机制尚不十分明确。研究证实叉形头转录蛋白因子-O(fork head transcr iption factor protein O,FOXO)在维持骨骼肌的功能中具有重要作用。现就COPD患者的骨骼肌障碍与FOXO的关系进行综述。
文摘MAP kinase-interacting kinase-2 (Mnk2) is one of the downstream kinasesactivated by MAP kinases. It phosphorylates the eukaryotic initiation factor 4E (elF4E), althoughthe role of elF4E phosphorylation and the role of Mnk2 in the process of proteintranslation are notwell understood. Except for elF4E, other physiological substrates of Mnk2 are still unidentified. Tolook for these unidentified substrates and to reveal the physiological function of Mnk2, weperformed a yeast two-hybrid screening with Mnk2 as the bait. The results demonstrated Mnk2 couldinteract with VHL (von Hippel-Lindau tumor suppressor), Rbx1 (ring-box1) and Cul2 (Cullin2) proteinsin yeast cells. Furthermore, we validated the interaction between Mnk2 and VHL proteins inmammalian cells by co-immunoprecipitation analysis. Because the three proteins VHL, Rbx1 and Cul2are all components of the CBC^(VHL) ubiquitin ligase E3 complex, it has been shown that Mnk2 caninteract with CBC^(VHL) complex, and is probably one of the newsubstrates of the CBC^(VHL) complex.Furthermore, during the interaction of Mnk2 with von Hippel-Lindau (VHL) tumor suppressor- bindingprotein 1 (VBP1), it appears that Mnk2 also joins to modulate cell shape as VBP1 plays an importantrole in the process of the maturation of the cytoskeleton and in the process of morphogenesis.
基金This work was supported by grants from the National Natural Science Foundation of China(Grant Nos.81602072,81902380,81820108022,and 81625018)Innovation Program of Shanghai Municipal Education Commission(Grant No.2019-01-07-00-10-E00056)+5 种基金Program of Shanghai Academic/Technology Research Leader(Grant No.18XD1403800)National High Technology Research and Development Program of China(Grant No.2015AA021107-019)Scientific Research Project of Shanghai Science and Technology Commission(Grant No.18411960600)Shanghai Technological Innovation Action Projects(Grant No.18411950800)Shanghai‘Rising Stars of Medical Talent’Youth Development Program,Outstanding Youth Medical Talents,2018the Shanghai Sailing Program(Grant No.17YF1405000).
文摘Objective:The hyperactivated neddylation pathway plays an important role in tumorigenesis and is emerging as a promising anticancer target.We aimed to study whether NEDD8(neural precursor cell expressed,developmentally down-regulated 8)might serve as a therapeutic target in esophageal squamous cell carcinoma(ESCC).Methods:The clinical relevance of NEDD8 expression was evaluated by using The Cancer Genome Atlas(TCGA)database and tissue arrays.NEDD8-knockdown ESCC cells generated with the CRISPR/Cas9 system were used to explore the anticancer effects and mechanisms.Quantitative proteomic analysis was used to examine the variations in NEDD8 knockdown-induced biological pathways.The cell cycle and apoptosis were assessed with fluorescence activated cell sorting.A subcutaneous-transplantation mouse tumor model was established to investigate the anticancer potential of NEDD8 silencing in vivo.Results:NEDD8 was upregulated at both the mRNA and protein expression levels in ESCC,and NEDD8 overexpression was associated with poorer overall patient survival(mRNA level:P=0.028,protein level:P=0.026,log-rank test).Downregulation of NEDD8 significantly suppressed tumor growth both in vitro and in vivo.Quantitative proteomic analysis revealed that downregulation of NEDD8 induced cell cycle arrest,DNA damage,and apoptosis in ESCC cells.Mechanistic studies demonstrated that NEDD8 knockdown led to the accumulation of cullin-RING E3 ubiquitin ligases(CRLs)substrates through inactivation of CRLs,thus suppressing the malignant phenotype by inducing cell cycle arrest and apoptosis in ESCC.Rescue experiments demonstrated that the induction of apoptosis after NEDD8 silencing was attenuated by DR5 knockdown.Conclusions:Our study elucidated the anti-ESCC effects and underlying mechanisms of NEDD8 knockdown,and validated NEDD8 as a potential target for ESCC therapy.
文摘Obesity is a serious health problem of our time. Dysfunction of adipogenesis, the differentiation of adipocytes, is a hallmark of obesity. Therefore here we investigate the role of the COP9 signalosome and of CHOP in the differentiation of LiSa-2 preadipocytes.
基金supported by the NCI grants(CA118762 and CA156744)to Yi Sun.
文摘SAG(Sensitive to Apoptosis Gene),also known as RBX2(RING box protein 2),ROC2(Regulator of Cullins 2),or RNF7(RING Finger Protein 7),was originally cloned in our laboratory as a redox inducible antioxi-dant protein and later characterized as the second member of the RBX/ROC RING component of the SCF(SKP1-CUL-F-box Proteins)E3 ubiquitin ligase.When acting alone,SAG scavenges oxygen radicals by forming inter-and intra-molecular disulfide bonds,whereas by forming a complex with other components of the SCF E3 ligase,SAG promotes ubiquitination and degradation of a number of protein substrates,includ-ing c-JUN,DEPTOR,HIF-1α,IκBα,NF1,NOXA,p27,and procaspase-3,thus regulating various signaling path-ways and biological processes.Specifically,SAG pro-tects cells from apoptosis,confers radioresistance,and plays an essential and non-redundant role in mouse embryogenesis and vasculogenesis.Furthermore,stress-inducible SAG is overexpressed in a number of human cancers and SAG overexpression correlates with poor patient prognosis.Finally,SAG transgenic expression in epidermis causes an early stage inhibi-tion,but later stage promotion,of skin tumorigenesis triggered by DMBA/TPA.Given its major role in pro-moting targeted degradation of tumor suppressive proteins,leading to apoptosis suppression and accel-erated tumorigenesis,SAG E3 ligase appears to be an attractive anticancer target.
