Mechanisms Of Ubiquitin C-terminal Hydrolase-L3 Mediated Regulation On Type Ⅰ-Interferon Signaling And Antiviral Activity

IFN-Ⅰ family plays essential roles in regulating antiviral immunity,cell proliferation,and immunomodulatory responses.Type-Ⅰ Interferons(IFN-Ⅰ)are important antiviral drugs which are widely used in clinical therapy of diverse viral infections.However,understanding the detailed mechanisms for IFN-Ⅰ antiviral signaling remains a major challenge,and may provide novel targets for IFN-based antiviral therapy.IFN-Ⅰ family triggers the signaling pathway through activation of IFN-Ⅰ receptors(IFNAR1 and IFNAR2),followed by tyrosine phosphorylation of Janus Kinase family including JAK1 and TYK2.Subsequently,activated JAK1 and Tyk2 induce tyrosine phosphorylation and activation of the signal transducers and activators of transcription(STAT1 and STAT2),which translocate into the nucleus to induce the transcription expression of interferon-stimulated genes(ISGs).Finally,these ISGs execute multiple biological functionsincluding antiviral defense.Deubiquitinaseshave been clarified to be important regulators for multiple biological functions including tumor growth,cell apoptosis,cell cycle and antimicrobial immuinity.Understanding of novel biological functions and regulatory mechanisms of different DUBs remains a major challenge.One of our recent studies demonstrates that the deubiquitinase USP2a regulates pY701-STAT1 ubiquitination.However,the roles of most of deubiquitinases in regulating IFN-Ⅰ antiviral signaling are still largely unexplored.Amongst these DUBs,ubiquitin C-terminal hydrolase-L3(UCHL3)belongs to UCH family.UCHL3 functions as a regulator for diverse biological functions including organismal development and tumor progress.However,Smadl is the only reported substrate of UCHL3 as a deubiquitinase so far.Interestingly,it has been shown that UCHL3 could regulate neddylation by removing Nedd8 from certain in vitro substrates,although the in vivo deneddylation substrates of UCHL3 have not been reported.However,as to UCHL3,the in vivo deubiquitination and deneddylation activities of UCHL3 and their corresponding biological funetions are largely unknown.Here,we find that Ubiquitin C-terminal hydrolase-L3(UCHL3)plays an important role in regulating type Ⅰ-interferon(IFN-Ⅰ)mediated antiviral response.Interestingly,we find that UCHL3 regulates COPS5-dependent deneddylation of Cullinl,which is an essential component of SCFβ-TrCP complex and associated with SCFp-TrCP activities.Furthermore,we reveal that UCHL3 physically interacts with COPS5,and determines the level and protein stability of cellular COPS5 by deubiquitinating COPS5.We further demonstrate that UCHL3 upregulates the levels of SCFβ-TrCP substrates including IFN-Ⅰreceptor IFNAR1,which enhances IFN-Ⅰ mediated signaling pathway and antiviral activity.These findings identify COPS5 as a novel in vivo substrate of UCHL3,and uncover the deubiquitination-deneddylation mediated regulation for IFN-Ⅰ signaling and antiviral function,which may provide a novel strategy for improving IFN-based antiviral therapy.