Multiple Roles of G3BP1 in Regulating STING-Dependent Interferon and Cytokine Induction by Cytosolic dsDNA and HSV-1...

Virus infection requires coordinated activation of pathogen-sensing, innate immune, and cellular stress response pathways to mount an effective antiviral defense. Recognition of nucleic acid pathogen-associated molecular patterns (PAMPs) by pattern recognition receptors (PRRs) initiates signaling cascades that drive the production of type I interferons (IFNs) and proinflammatory cytokines. These responses are often accompanied by the activation of integrated stress response pathways that help optimize host defense. Cytosolic double-stranded dsDNA, generated during viral infection or released from damaged mitochondria, is sensed by cyclic GMP-AMP synthase (cGAS), which generates 2'3'-cGAMP to activate stimulator of interferon genes (STING). Activated STING translocates from the endoplasmic reticulum to the Golgi, where it drives TBK1-dependent IFN and cytokine production. Previous reports show that cGAS activity is enhanced by Ras-GAP SH3 domain binding protein 1 (G3BP1), a key nucleator of stress granules (SGs), independent of its role in SG assembly. Here, we identify a non-canonical role of G3BP1 as a regulator of DNA sensing responses at multiple levels, including STING intracellular trafficking, in addition to potentiating cGAS activity. Loss of G3BP1 impaired STING-dependent IFN and cytokine responses to HSV-1 infection and viral DNA. G3BP1-deficient cells showed reduced cGAMP-induced STING translocation to the Golgi, induction of type I IFN and proinflammatory cytokines, and activation of the ER stress kinase PERK and stress granule formation. Together, these findings demonstrate G3BP1-STING as a node linking DNA sensing, innate immunity, and stress signaling with broad implications for antiviral defense and diseases characterized by aberrant DNA sensing and stress responses, including neurodegeneration, fibrosis, and autoimmunity.