Identification of an STING inhibitor targeting the allosteric transmembrane domains.

Overactive stimulator of interferon gene (STING) signaling drives inflammatory and autoimmune diseases, making STING inhibition a promising therapeutic strategy. However, the complex binding mechanisms and limited structural diversity hinder the development of STING inhibitors. In this study, we identified a small-molecule STING inhibitor, Y-320, via cell-based screening. It binds STING with nanomolar affinity and potently inhibits STING-mediated interferon signaling in human and mouse cells. Mechanistically, Y-320 blocks the Golgi translocation and phosphorylation of STING, preventing interferon regulatory factor 3 (IRF3) recruitment. Notably, Y-320 allosterically targets the non-canonical transmembrane domain (TMD) pocket without competing with the endogenous agonist 2'3'-cGAMP by engaging residues Y46 and W119 in the transmembrane helices 2 and 4. Importantly, Y-320 alleviated cisplatin-induced acute kidney injury in mice in a STING-dependent manner. This work not only reveals an additional mechanism underlying the regulatory complexity of STING but also provides a TMD-targeted allosteric STING inhibitor with demonstrated efficacy in both in vitro and in vivo models.