biostudies-literatureRao SDPew Charitable TrustsNIAID NIH HHSMarie-Josée Kravis Women in Science Endeavor (WISE) fellowshipNCI NIH HHSGabrielle’s Angel Foundation for Cancer ResearchU.S. Department of Health & Human Services | National Institutes of HealthNIGMS NIH HHSMr. William H and Mrs. Alice Goodwin, the Commonwealth Foundation for Cancer Research, and The Center for Experimental Therapeutics of Memorial Sloan Kettering Cancer Center; the Emerson Collective565-574https://www.ebi.ac.uk/biostudies/studies/S-EPMC9179932biostudies-literatureUnknown18(5)Inflammasomes are multiprotein complexes that sense intracellular danger signals and induce pyroptosis. CARD8 and NLRP1 are related inflammasomes that are repressed by the enzymatic activities and protein structures of the dipeptidyl peptidases 8 and 9 (DPP8/9). Potent DPP8/9 inhibitors such as Val-boroPro (VbP) activate both NLRP1 and CARD8, but chemical probes that selectively activate only one have not been identified. Here we report a small molecule called CQ31 that selectively activates CARD8. CQ31 inhibits the M24B aminopeptidases prolidase (PEPD) and Xaa-Pro aminopeptidase 1 (XPNPEP1), leading to the accumulation of proline-containing peptides that inhibit DPP8/9 and thereby activate CARD8. NLRP1 is distinct from CARD8 in that it directly contacts DPP8/9's active site; these prolineNature chemical biologyM24B aminopeptidase inhibitors selectively activate the CARD8 inflammasome.PMC9179932T32 GM007739N/AT32 GM007739-AndersenP30 CA008748R01 AI163170R25AI140472T32 GM115327-TanR25 AI140472T32 GM115327R01 AI137168F30 CA243444F30 CA008748Cross JRChen QGriswold ARRao SDYou SBall DPChui AJCovelli DJBhattacharjee AWang QOrth-He ELSaoi MBachovchin DAHuang HCfalseM24B aminopeptidase inhibitors selectively activate the CARD8 inflammasome.Inflammasomes are multiprotein complexes that sense intracellular danger signals and induce pyroptosis. CARD8 and NLRP1 are related inflammasomes that are repressed by the enzymatic activities and protein structures of the dipeptidyl peptidases 8 and 9 (DPP8/9). Potent DPP8/9 inhibitors such as Val-boroPro (VbP) activate both NLRP1 and CARD8, but chemical probes that selectively activate only one have not been identified. Here we report a small molecule called CQ31 that selectively activates CARD8. CQ31 inhibits the M24B aminopeptidases prolidase (PEPD) and Xaa-Pro aminopeptidase 1 (XPNPEP1), leading to the accumulation of proline-containing peptides that inhibit DPP8/9 and thereby activate CARD8. NLRP1 is distinct from CARD8 in that it directly contacts DPP8/9's active site; these proline2022-01-01T00:00:00Z2022 May2026-05-10T06:50:54.773Z2025-02-19T03:25:55.457ZS-EPMC91799323516544310.1038/s41589-021-00964-7