Study On The Mechanism Of MAP4K3 Enhancing Antiviral Natural Immunity

MAP4K3(Mitogen-activated protein kinase kinase kinase kinase kinase 3,also known as GLK),a Ste20-like serine/threonine kinase family member,,is widely expressed in human tissues and initially identified as an upstream activator of the JNK(C-Jun NH2-Terminal kinase)pathway.MAP4K3 is proven to play crucial roles in stress response,inflammatory response,T cell receptor signaling pathway,cell cycle.Type Ⅰ interferon(IFN-I,including IFN-β and IFN-α),the most representative cytokines in innate antiviral immunity,serves as the first line of intracellular antiviral defense,exerting antiviral immunomodulatory and antitumor effects,However,the role of MAP4K3 in IFN-I-mediated antiviral innate immunity remains unclear.In this study,exogenous expression of MAP4K3 was found to significantly enhance the innate antiviral immune response via screening the protein kinase library and inhibit viral proliferation,while MAP4K3 depletion or deletion had the opposite effect.Subsequently.MAP4K3 was found to only enhance RLR signaling pathway,but not cGAS-STING and other DNA recognition pathway.Furthermore,MAP4K3 was found to interact with MAVS,and promote the K63-linked polyubiquitination and aggregation of MAVS.Mass spectrometry analysis showed that MAP4K3 directly phosphorylated MAVS at Ser249,Subsequently,the MAVS S249A knockin HEK 293T cells were generated to verify the phosphorylation site of MAVS by MAP4K3.MAP4K3 KO mice display comprimosed innate antiviral response,exacerbated viral proliferation,lung lesions and mortality after VSV infection.Moreover,the MAP4K3 activition was found to be attenuated by IFN-I signaling,which might serve as a "brake"mechanism to prevent the over activation of innate antiviral response.This study clarified the molecular mechanism of MAP4K3 enhancing RLR pathway,and verified the pivotal role of MAP4K3 in innate immunity in mice.Furthermore.IFN-I signaling could blunt the activity of MAP4K3.contributing to the precise control of antiviral response.Those results first identified MAP4K3 to be an activator of antiviral innate immunity,and further clarified its molecular mechanism,permiting development of new antiviral drugs and the optimization of therapeutic strategies against viral infection.