1. DPP9’s Enzymatic Activity and Not Its Binding to CARD8 Inhibits Inflammasome Activation
- Author
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Sahana D. Rao, Cornelius Y. Taabazuing, Daniel A. Bachovchin, Andrew R. Griswold, Ashley J. Chui, Abir Bhattacharjee, and Daniel P. Ball
- Subjects
0301 basic medicine ,Dipeptidases ,Inflammasomes ,Protein Conformation ,Mutant ,NLR Proteins ,Plasma protein binding ,01 natural sciences ,Biochemistry ,Organofluorophosphonates ,Serine ,03 medical and health sciences ,medicine ,Humans ,Protease Inhibitors ,Letters ,Dipeptidyl-Peptidases and Tripeptidyl-Peptidases ,Adaptor Proteins, Signal Transducing ,chemistry.chemical_classification ,010405 organic chemistry ,HEK 293 cells ,Signal transducing adaptor protein ,Inflammasome ,General Medicine ,Neoplasm Proteins ,0104 chemical sciences ,Cell biology ,CARD Signaling Adaptor Proteins ,HEK293 Cells ,030104 developmental biology ,Enzyme ,chemistry ,Mutation ,Molecular Medicine ,Signal transduction ,Apoptosis Regulatory Proteins ,Protein Binding ,Signal Transduction ,medicine.drug - Abstract
Inflammasomes are multiprotein complexes formed in response to pathogens. NLRP1 and CARD8 are related proteins that form inflammasomes, but the pathogen-associated signal(s) and the molecular mechanisms controlling their activation have not been established. Inhibitors of the serine dipeptidyl peptidases DPP8 and DPP9 (DPP8/9) activate both NLRP1 and CARD8. Interestingly, DPP9 binds directly to NLRP1 and CARD8, and this interaction may contribute to the inhibition of NLRP1. Here, we use activity-based probes, reconstituted inflammasome assays, and mass spectrometry-based proteomics to further investigate the DPP9–CARD8 interaction. We show that the DPP9–CARD8 interaction, unlike the DPP9–NLRP1 interaction, is not disrupted by DPP9 inhibitors or CARD8 mutations that block autoproteolysis. Moreover, wild-type, but not catalytically inactive mutant, DPP9 rescues CARD8-mediated cell death in DPP9 knockout cells. Together, this work reveals that DPP9’s catalytic activity and not its binding to CARD8 restrains the CARD8 inflammasome and thus suggests the binding interaction likely serves some other biological purpose.
- Published
- 2019
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