A sesterterpenoid derivative alleviates ulcerative colitis through targeting ProRS to suppress the NLRP3 inflammasome

Ulcerative colitis (UC) is a prevalent inflammatory bowel disease that affects millions of people worldwide, for which no definitive cure currently exists. Herein, we report the discovery of a novel sesterterpenoid derivative, ColD14, with a complicated cage-like structure and contiguous stereogenic centers, which exhibits significant anti-NLRP3 inflammasome activity. Proteomic and biochemical studies identified glutamyl-prolyl tRNA synthetase (EPRS) as a direct target of ColD14. Both EPRS knockdown and pharmacological inhibition by ColD14 reduced NLRP3 inflammasome activation, underscoring the crucial role of EPRS in inflammatory processes. Mechanistically, through the molecular interaction with amino acid residues R1152, E1154, and R1278 at the ATP site, ColD14 inhibited prolyl-tRNA synthetase (ProRS) activity. This suppression triggered the amino acid response (AAR) pathway and consequently attenuated NLRP3 inflammasome activation via mitophagy regulation. In vivo, ColD14 activated the AAR signaling pathway, triggered mitophagy, and inhibited NLRP3 inflammasome activation, thereby alleviating DSS-induced colitis in mice. Taken together, our findings underscored the significance of EPRS in NLRP3 inflammasome activation and suggested that the EPRS inhibitor, ColD14, may be valuable in ulcerative colitis therapy via the EPRS-AAR-mitophagy axis.