GNAQ Negatively Regulates Antiviral Innate Immune Responses in a Calcineurin-Dependent Manner

Although guanine nucleotide-binding protein (G protein)-coupled receptors (GPCRs) constitute the largest cell surface membrane receptor family and transduce thousands of extracellular signals into the cytoplasm, only four kinds of G protein alpha subunits (G alpha s, G alpha i/o, G alpha q/11, and G alpha 12/13) are coupled to regulate cAMP or phosphatidylinositol signals. Growing evidence suggests that viruses tend to hijack GPCRs and harness their activated intracellular signaling pathways. Thus, understanding the roles of G protein signaling will further uncover the GPCR signaling pathways that are exploited by viruses. In this study, we demonstrate that the expression of GNAQ (Gq alpha subunit) was downregulated during viral infection and that small interfering RNA-mediated GNAQ knockdown protected host cells from both vesicular stomatitis virus (VSV) and HSV type 1 infection. Meanwhile, VSV and HSV type 1 replication was reduced significantly in Gnaq-deficient macrophages. Accordingly, the VSV distribution in the liver, spleen, and lung was reduced in Gnaq-deficient mice during VSV infection, and Gnaq-deficient mice were much more resistant to VSV infection than wild-type mice. Mechanistically, GNAQ limits type I IFN production through the canonical PLC-beta/Ca2+/CALNA signaling pathway, which has been demonstrated to dephosphorylate virus-activated TANK-binding kinase 1 (TBK1). Thus, our data demonstrate that GNAQ negatively regulates the antiviral innate immune responses in a calcineurin-dependent manner. These findings also provide insights into the function and cross-talk of the classic GPCR signaling pathway with antiviral innate immune responses and suggest a potential therapeutic role for GNAQ in controlling viral diseases.