Fig. 1: Overview of the cGAS-STING signaling pathway.
From: Molecular mechanisms of mitochondrial DNA release and activation of the cGAS-STING pathway

The host immune response is initiated by the recognition of cytosolic DNA, such as pathogen-derived nucleic acids (e.g., viruses and bacteria) and self-DNA (e.g., from dying cells, tumor cells or mtDNA). Upon recognition of cytosolic DNA, cGAS catalyzes the formation of cGAMP and thereby activates STING. STING then activates TBK1, which phosphorylates IRF3. Phosphorylated IRF3 activates the expression of type I IFNs in the nucleus. STING also activates NF-κB by phosphorylating the kinase IKK. NF-κB then activates the transcription of genes encoding proinflammatory cytokines.