Identification of immune activation DNA inside cells cyclic GMP-AMP synthase (cgas) is a key sensor of cytosolic double-stranded DNA (dsdna) that activates the stimulator of interferon genes (sting)…

The National Institute of Allergy and Infectious Diseases awarded the University of Southern California $456,500 on February 6, 2026, under the Allergy and Infectious Diseases Research program (CFDA 93.855) to develop and apply photochemical crosslinking technology for identifying immune-activation DNA ligands that bind the cGAS protein in living cells.

The research addresses the transient and weak nature of cGAS–DNA interactions, which conventional crosslinking methods fail to capture. Aim 1 focuses on adapting and optimizing photochemical crosslinking for cGAS–DNA interactions with high efficiency and specificity. Aim 2 applies the method to establish a cGAS BioID proximity labeling ChIP-seq protocol, enabling genome-wide identification of endogenous DNA ligands that activate cGAS in TRex1 knockout mouse embryonic fibroblast cells, a cellular model of Aicardi–Goutieres syndrome. By uncovering sources and mechanisms of immune-activating DNA, the work aims to inform novel diagnostic and therapeutic strategies targeting cGAS in autoimmune, inflammatory, and age-related diseases.

The award is structured as a project grant, the standard NIH R21 mechanism supporting high-risk, innovative research. Work is performed in Los Angeles, California, with a period of performance from the award date through January 31, 2028.

Identification of immune activation DNA inside cells cyclic GMP-AMP synthase (cgas) is a key sensor of cytosolic double-stranded DNA (dsdna) that activates the stimulator of interferon genes (sting) pathway, triggering immune responses against infections and cellular damage. While cgas plays a protective role in pathogen defense and tumor suppression, its aberrant activation by self-DNA is implicated in autoimmune diseases (e.g., aicardi- goutières syndrome, systemic lupus erythematosus) and chronic inflammation associated with aging. Despite extensive studies on cgas-sting signaling, the physiological dsdna ligands that activate cgas under various cellular conditions remain poorly characterized due to the transient and weak nature of cgas-DNA interactions, which conventional crosslinking methods fail to capture. To address this challenge, we propose to develop and apply a novel photochemical crosslinking approach to covalently capture cgas-DNA complexes in living cells. Aim 1 focuses on adapting and optimizing this crosslinking technology for cgas-DNA interactions, ensuring high efficiency and specificity. Aim 2 applies this method to establish a first-in-class cgas bfpx chip-SEQ protocol, enabling the genome-wide identification of endogenous DNA ligands that activate cgas in TREX1 KO MEF cells-a cellular model of aicardi- goutières syndrome. This innovative approach will provide a powerful tool for studying cgas-sting pathway activation across diverse physiological and pathological contexts. By uncovering the sources and mechanisms of immune-activating DNA, our work will pave the way for novel diagnostic and therapeutic strategies targeting cgas in autoimmune, inflammatory, and age-related diseases.