Phosphorylation Of MAVS By Nemo-like Kinase(NLK) For Degradation Regulates The Antiviral Innate Immune Response

Mitochondrial antiviral-signaling protein,which we call MAVS/VISA,is essential for antiviral immunity.When the RNA viral infects the cells,it will be recognized by the RIG-I like receptor.And then,the RIG-I like receptor will change it's conformation and transfer to the outer membrane of mitochondrial where it will interact with MAVS.At the moment,MAVS start recruiting IRF3 and phosphorylation it which make it enter its nucleus,then the pIRF3 promotes the transcription of Type I interferon in the nucleus and the Type I interferon will take part in the procedure of innate immunity.Although the function of MAVS in the pathway of innate immunity has been done many researches,the molecular mechanisms responsible for its tight regulation remain poorly understood.Here,when we do the research on innate immunity,we find NLK can interact with MAVS and degrade it through phosphorylation it,so that NLK can inhibits IFN-? induction and the antiviral immune response.NLK depletion promotes virus-induced antiviral cytokine production and decreases viral replication,which is potently rescued by the reintroduction of NLK.Moreover,the depletion of NLK promotes antiviral effects and increases survival time of mouse after infected by VSV.NLK interacts with and phosphorylates MAVS at four sites,thereby inducing degradation of MAVS and subsequent inactivation of IRF3.After constructing the plasmid of MAVS mutant,we transfect them with NLK and show that MAVS cannot be degraded by NLK.After then,we pay attention to the localization of NLK.According to the previus findings,we have known that MAVS is localizing on the Mitochondria and peroxisome.Basing on it,we show that most NLK is localizing on the Mitochondria and peroxisome.After the infection of SeV,the Co-localization is becoming much more.Then the Immunoblotting precipitation shows that NLK only interacts with the MAVS mutant which only localize on the Mitochondria and peroxisome.The most importantly,the peptide derived from MAVS promote viral-induced IFN-? production and antagonize viral replication in vitro and in vivo.The Immunoblotting precipitation shows the mechanisms how NAMDAP works.NAMDAP can competitive binding to NLK with MAVS,as a result,NLK will phosphorylate less MAVS and these MAVS will not be degraded.In the Survival assay,mice were infected with VSV and NAMDAP via tail vein injection.The titers were reduced in mice injected with NAMDAP in a dose-dependent manner compared with mice not receiving NAMDAP injection and mouse injected with NAMDAP greatly increased survival of mouse whereas mouse injected without NAMDAP all died.These findings provide direct insights into the molecular mechanisms by which phosphorylation of MAVS regulates its degradation and influences its activation and identify an important peptide target for propagating antiviral responses.