RNA interference(RNAi)is an intrinsic antiviral immune mechanism conserved in diverse eukaryotic organisms.However,the mechanism by which antiviral RNAi in mammals is regulated is poorly understood.In this study,we un...RNA interference(RNAi)is an intrinsic antiviral immune mechanism conserved in diverse eukaryotic organisms.However,the mechanism by which antiviral RNAi in mammals is regulated is poorly understood.In this study,we uncovered that the E3 ubiquitin ligase STIP1 homology and U-box-containing protein 1(STUB1)was a new regulator of the RNAi machinery in mammals.We found that STUB1 interacted with and ubiquitinated AGO2,and targeted it for degradation in a chaperon-dependent manner.STUB1 promoted the formation of Lys48(K48)-linked polyubiquitin chains on AGO2,and facilitated AGO2 degradation through ubiquitin-proteasome system.In addition to AGO2,STUB1 also induced the protein degradation of AGO1,AGO3 and AGO4.Further investigation revealed that STUB1 also regulated Dicer's ubiquitination via K48-linked polyubiquitin and induced the degradation of Dicer as well as its specialized form,termed antiviral Dicer(avi Dicer)that expresses in mammalian stem cells.Moreover,we found that STUB1 deficiency up-regulated Dicer and AGO2,thereby enhancing the RNAi response and efficiently inhibiting viral replication in mammalian cells.Using the newborn mouse model of Enterovirus A71(EV-A71),we confirmed that STUB1 deficiency enhanced the virus-derived si RNAs production and antiviral RNAi,which elicited a potent antiviral effect against EV-A71 infection in vivo.In summary,our findings uncovered that the E3 ubiquitin ligase STUB1 was a general regulator of the RNAi machinery by targeting Dicer,avi Dicer and AGO1–4.Moreover,STUB1 regulated the RNAi response through mediating the abundance of Dicer and AGO2 during viral infection,thereby providing novel insights into the regulation of antiviral RNAi in mammals.展开更多
Chikungunya virus(CHIKV)is a re-emerging mosquito-transmitted RNA virus causing joint and muscle pain.To better understand how CHIKV rewires the host cell and usurps host cell functions,we generated a systematic CHIKV...Chikungunya virus(CHIKV)is a re-emerging mosquito-transmitted RNA virus causing joint and muscle pain.To better understand how CHIKV rewires the host cell and usurps host cell functions,we generated a systematic CHIKV-human protein-protein interaction map and revealed several novel connections that will inform further mechanistic studies.One of these novel interactions,between the viral protein E1 and STIP1 homology and U-box containing protein 1(STUB1),was found to mediate ubiquitination of E1 and degrade E1 through the proteasome.Capsid associated with G3BP1,G3BP2 and AAAþATPase valosin-containing protein(VCP).Furthermore,VCP inhibitors blocked CHIKV infection,suggesting VCP could serve as a therapeutic target.Further work is required to fully understand the functional consequences of these interactions.Given that CHIKV proteins are conserved across alphaviruses,many virus-host protein-protein interactions identified in this study might also exist in other alphaviruses.Construction of interactome of CHIKV provides the basis for further studying the function of alphavirus biology.展开更多
Autophagy is a major degradation system which processes substrates through the steps of auto- phagosome formation, autophagosome-lysosome fusion, and substrate degradation. Aberrant autophagic flux is present in many ...Autophagy is a major degradation system which processes substrates through the steps of auto- phagosome formation, autophagosome-lysosome fusion, and substrate degradation. Aberrant autophagic flux is present in many pathological conditions including neurodegeneration and tumors. CHIP/STUB1, an E3 ligase, plays an important role in neurodegeneration. In this study, we identified the regulation of autophagic flux by CHIP （carboxy-terminus of HscT0-interacting protein）. Knockdown of CHIP induced autophagosome formation through increasing the PTEN protein level and decreasing the AKT/mTOR activity as well as decreasing phosphorylation of ULK1 on Ser757. However, degradation of the autophagic substrate p62 was disturbed by knockdown of CHIP, suggesting an abnormality of autophagic flux. Furthermore, knockdown of CHIP increased the susceptibility of cells to autophagic cell death induced by bafilomycin AI. Thus, our data suggest that CHIP plays roles in the regulation of autophagic flux.展开更多
基金the National Natural Science Foundation of China(31970169 to X.Z.and 82172269 and 81873964 to Y.Q.)the International Partnership Program of Chinese Academy of Sciences(153B42KYSB20200004 to X.Z.)+3 种基金the Young Top-notch Talent Cultivation Program of Hubei Province(Y.Q.)the Grant from the CAS Youth Innovation Promotion Association(2020332 to Y.Q.)the Hubei Province Natural Science Funds for Distinguished Young Scholar(2021CFA047 to Y.Q.)the Young Top-notch Talent Cultivation Program of Hubei Province(Y.Q.)。
文摘RNA interference(RNAi)is an intrinsic antiviral immune mechanism conserved in diverse eukaryotic organisms.However,the mechanism by which antiviral RNAi in mammals is regulated is poorly understood.In this study,we uncovered that the E3 ubiquitin ligase STIP1 homology and U-box-containing protein 1(STUB1)was a new regulator of the RNAi machinery in mammals.We found that STUB1 interacted with and ubiquitinated AGO2,and targeted it for degradation in a chaperon-dependent manner.STUB1 promoted the formation of Lys48(K48)-linked polyubiquitin chains on AGO2,and facilitated AGO2 degradation through ubiquitin-proteasome system.In addition to AGO2,STUB1 also induced the protein degradation of AGO1,AGO3 and AGO4.Further investigation revealed that STUB1 also regulated Dicer's ubiquitination via K48-linked polyubiquitin and induced the degradation of Dicer as well as its specialized form,termed antiviral Dicer(avi Dicer)that expresses in mammalian stem cells.Moreover,we found that STUB1 deficiency up-regulated Dicer and AGO2,thereby enhancing the RNAi response and efficiently inhibiting viral replication in mammalian cells.Using the newborn mouse model of Enterovirus A71(EV-A71),we confirmed that STUB1 deficiency enhanced the virus-derived si RNAs production and antiviral RNAi,which elicited a potent antiviral effect against EV-A71 infection in vivo.In summary,our findings uncovered that the E3 ubiquitin ligase STUB1 was a general regulator of the RNAi machinery by targeting Dicer,avi Dicer and AGO1–4.Moreover,STUB1 regulated the RNAi response through mediating the abundance of Dicer and AGO2 during viral infection,thereby providing novel insights into the regulation of antiviral RNAi in mammals.
基金supported by National Natural Science Foundation of China (82072270 and 82272306)Taishan Scholars Program (tstp20221142)+1 种基金Shandong Provincial Natural Science Foundation (ZR2021QC095)Academic Promotion Programme of Shandong First Medical University (2019LJ001).
文摘Chikungunya virus(CHIKV)is a re-emerging mosquito-transmitted RNA virus causing joint and muscle pain.To better understand how CHIKV rewires the host cell and usurps host cell functions,we generated a systematic CHIKV-human protein-protein interaction map and revealed several novel connections that will inform further mechanistic studies.One of these novel interactions,between the viral protein E1 and STIP1 homology and U-box containing protein 1(STUB1),was found to mediate ubiquitination of E1 and degrade E1 through the proteasome.Capsid associated with G3BP1,G3BP2 and AAAþATPase valosin-containing protein(VCP).Furthermore,VCP inhibitors blocked CHIKV infection,suggesting VCP could serve as a therapeutic target.Further work is required to fully understand the functional consequences of these interactions.Given that CHIKV proteins are conserved across alphaviruses,many virus-host protein-protein interactions identified in this study might also exist in other alphaviruses.Construction of interactome of CHIKV provides the basis for further studying the function of alphavirus biology.
基金supported in part by the National Natural Science Foundation of China (31330030 and 31471012)the National Basic Research Development Program of China (2012CB947602)a Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘Autophagy is a major degradation system which processes substrates through the steps of auto- phagosome formation, autophagosome-lysosome fusion, and substrate degradation. Aberrant autophagic flux is present in many pathological conditions including neurodegeneration and tumors. CHIP/STUB1, an E3 ligase, plays an important role in neurodegeneration. In this study, we identified the regulation of autophagic flux by CHIP （carboxy-terminus of HscT0-interacting protein）. Knockdown of CHIP induced autophagosome formation through increasing the PTEN protein level and decreasing the AKT/mTOR activity as well as decreasing phosphorylation of ULK1 on Ser757. However, degradation of the autophagic substrate p62 was disturbed by knockdown of CHIP, suggesting an abnormality of autophagic flux. Furthermore, knockdown of CHIP increased the susceptibility of cells to autophagic cell death induced by bafilomycin AI. Thus, our data suggest that CHIP plays roles in the regulation of autophagic flux.
