Non-canonical cGAS-STING Signaling: A Nexus Between Cellular Senescence and Chronic Inflammation in Aging

Non-canonical cGAS–STING signaling emerges from alterations in classical cytosolic DNA sensing, in which cGAS-generated 2′3′-cGAMP normally activates ER-resident STING, driving TBK1-IRF3–dependent type I/III interferon and NF-κB responses that eliminate pathogens and couple innate and adaptive immunity. In senescent and progeroid cells, de Faria and colleagues identified elevated DNA damage, cytoplasmic DNA accumulation, and SASP/ISG induction despite unchanged cGAMP levels and diminished classical STING–TBK1–IRF3 activation, with STING instead showing nuclear envelope and chromatin localization and forming alternative complexes that reprogram inflammatory and senescence-related transcription. This non-canonical mode features sustained STAT1 and NF-κB activation, robust SASP output, and organ-specific pathogenic effects on vascular smooth muscle, white adipose tissue, and connective tissues, while exerting relatively minor influence on cardiac muscle. Gulen and colleagues demonstrated that STING drives systemic low-grade inflammation in naturally aged animals, promoting inflammatory and interferon signatures in kidney, liver, and brain, microglial activation, neuronal and synaptic loss, and functional decline that can be ameliorated by pharmacological STING inhibition. Additional work links cGAS–STING activation to NLRP3-dependent IL-1β maturation in Alzheimer’s disease models and to metabolic reprogramming, mitochondrial dysfunction, and deterioration of the NAD⁺–Sirtuin axis. Across these contexts, pharmacological or genetic inhibition of cGAS–STING reduces SASP and ISG expression, limits inflammatory damage, and improves cellular and organismal phenotypes, highlighting non-canonical cGAS–STING signaling as a central driver of inflammation-mediated senescence and metabolic decline in aging and progeroid states.