The von Hippel-Lindau tumor suppressor protein(VHL),an E3 ubiquitin ligase,functions as a critical regulator of the oxygen-sensing pathway for targeting hypoxia-inducible factors.Recent evidence suggests that mammalia...The von Hippel-Lindau tumor suppressor protein(VHL),an E3 ubiquitin ligase,functions as a critical regulator of the oxygen-sensing pathway for targeting hypoxia-inducible factors.Recent evidence suggests that mammalian VHL may also be critical to the NF-κB signaling pathway,although the specific molecular mechanisms remain unclear.Herein,the roles of mandarin fish(Siniperca chuatsi)VHL(scVHL)in the NF-κB signaling pathway and mandarin fish ranavirus(MRV)replication were explored.The transcription of scVHL was induced by immune stimulation and MRV infection,indicating a potential role in innate immunity.Dual-luciferase reporter gene assays and reverse transcription quantitative PCR(RT-qPCR)results demonstrated that scVHL evoked and positively regulated the NF-κB signaling pathway.Treatment with NF-κB signaling pathway inhibitors indicated that the role of scVHL may be mediated through scIKKα,scIKKβ,scIκBα,or scp65.Co-immunoprecipitation(Co-IP)analysis identified scIκBαas a novel target protein of scVHL.Moreover,scVHL targeted scIκBαto catalyze the formation of K63-linked polyubiquitin chains to activate the NF-κB signaling pathway.Following MRV infection,NF-κB signaling remained activated,which,in turn,promoted MRV replication.These findings suggest that scVHL not only positively regulates NF-κB but also significantly enhances MRV replication.This study reveals a novel function of scVHL in NF-κB signaling and viral infection in fish.展开更多
Ring finger protein 122(RNF122),an E3 ubiquitin ligase,orchestrates antiviral immune responses in mammals by targeting retinoic acid-inducible gene 1 and melanoma differentiation-associated gene 5 for ubiquitination.H...Ring finger protein 122(RNF122),an E3 ubiquitin ligase,orchestrates antiviral immune responses in mammals by targeting retinoic acid-inducible gene 1 and melanoma differentiation-associated gene 5 for ubiquitination.However,its functional relevance in teleosts has yet to be clearly defined,particularly regarding the identification of substrate-specific regulatory sites.This study characterized RNF122 from mandarin fish(Siniperca chuatsi),termed scRNF122,and investigated its regulatory impact on stimulator of interferon genes(STING)-mediated antiviral signaling.Results showed that scRNF122 expression was up-regulated in response to mandarin fish ranavirus(MRV)infection,and its overexpression suppressed scSTING-mediated interferon(IFN)production and enhanced MRV replication.Co-immunoprecipitation confirmed a direct interaction between scRNF122 and scSTING.Functional assays demonstrated that scRNF122 facilitated scSTING degradation through the ubiquitin-proteasome pathway,a process impeded by MG132 treatment.Ubiquitination analyses of various scSTING mutants revealed that scRNF122 catalyzed scSTING ubiquitination at K95,K117,and K155 residues.Moreover,scRNF122 significantly impaired scSTING-dependent antiviral responses by engaging negative regulatory elements within the signaling cascade.Overall,scRNF122 was identified as a negative modulator of STING-mediated IFN signaling in mandarin fish,diminishing STING-dependent antiviral activity and promoting its degradation via the ubiquitin-proteasome pathway at lysine residues K95,K117,and K155.These findings provide mechanistic insight into the post-translational control of STING in teleosts and establish a foundation for future investigations into antiviral immune regulation.展开更多
基金supported by the National Key Research and Development Program of China(2022YFE0203900)Guangdong Key Research and Development Program(2021B0202040002 and 2022B1111030001)+4 种基金China Agriculture Research System(CARS-46)Guangdong Basic and Applied Basic Research Foundation(2021A1515010647)Basic and Applied Basic Research Project of Guangzhou Science and Technology Plan Project(202102020299)Science and Technology Planning Project of Guangdong(2023B1212060023)Guangdong Laboratory for Lingnan Modern Agriculture(NZ2021018)。
文摘The von Hippel-Lindau tumor suppressor protein(VHL),an E3 ubiquitin ligase,functions as a critical regulator of the oxygen-sensing pathway for targeting hypoxia-inducible factors.Recent evidence suggests that mammalian VHL may also be critical to the NF-κB signaling pathway,although the specific molecular mechanisms remain unclear.Herein,the roles of mandarin fish(Siniperca chuatsi)VHL(scVHL)in the NF-κB signaling pathway and mandarin fish ranavirus(MRV)replication were explored.The transcription of scVHL was induced by immune stimulation and MRV infection,indicating a potential role in innate immunity.Dual-luciferase reporter gene assays and reverse transcription quantitative PCR(RT-qPCR)results demonstrated that scVHL evoked and positively regulated the NF-κB signaling pathway.Treatment with NF-κB signaling pathway inhibitors indicated that the role of scVHL may be mediated through scIKKα,scIKKβ,scIκBα,or scp65.Co-immunoprecipitation(Co-IP)analysis identified scIκBαas a novel target protein of scVHL.Moreover,scVHL targeted scIκBαto catalyze the formation of K63-linked polyubiquitin chains to activate the NF-κB signaling pathway.Following MRV infection,NF-κB signaling remained activated,which,in turn,promoted MRV replication.These findings suggest that scVHL not only positively regulates NF-κB but also significantly enhances MRV replication.This study reveals a novel function of scVHL in NF-κB signaling and viral infection in fish.
基金supported by the National Key Research and Development Program of China(2022YFE0203900,2024YFD2401101)China Agriculture Research System(CARS-46)+1 种基金National Natural Science Foundation of China(32473201)Guangdong S&T Program(2022B1111030001,2024B1212040007)。
文摘Ring finger protein 122(RNF122),an E3 ubiquitin ligase,orchestrates antiviral immune responses in mammals by targeting retinoic acid-inducible gene 1 and melanoma differentiation-associated gene 5 for ubiquitination.However,its functional relevance in teleosts has yet to be clearly defined,particularly regarding the identification of substrate-specific regulatory sites.This study characterized RNF122 from mandarin fish(Siniperca chuatsi),termed scRNF122,and investigated its regulatory impact on stimulator of interferon genes(STING)-mediated antiviral signaling.Results showed that scRNF122 expression was up-regulated in response to mandarin fish ranavirus(MRV)infection,and its overexpression suppressed scSTING-mediated interferon(IFN)production and enhanced MRV replication.Co-immunoprecipitation confirmed a direct interaction between scRNF122 and scSTING.Functional assays demonstrated that scRNF122 facilitated scSTING degradation through the ubiquitin-proteasome pathway,a process impeded by MG132 treatment.Ubiquitination analyses of various scSTING mutants revealed that scRNF122 catalyzed scSTING ubiquitination at K95,K117,and K155 residues.Moreover,scRNF122 significantly impaired scSTING-dependent antiviral responses by engaging negative regulatory elements within the signaling cascade.Overall,scRNF122 was identified as a negative modulator of STING-mediated IFN signaling in mandarin fish,diminishing STING-dependent antiviral activity and promoting its degradation via the ubiquitin-proteasome pathway at lysine residues K95,K117,and K155.These findings provide mechanistic insight into the post-translational control of STING in teleosts and establish a foundation for future investigations into antiviral immune regulation.
