Dataset Information

DPP9 activity and not protein binding inhibits the CARD8 inflammasome

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) were recently discovered to activate both NLRP1 and CARD8. Interestingly, DPP9 binds directly to NLRP1 and CARD8, and this interaction, in addition to DPP9’s catalytic activity, 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 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 DPP9 activity and not direct protein binding restrains the CARD8 inflammasome, and suggests the binding interaction likely serves some other biological purpose.

INSTRUMENT(S): Orbitrap Fusion Lumos

ORGANISM(S): Homo Sapiens (human)

TISSUE(S): Cell Culture

SUBMITTER: Andrew Griswold

LAB HEAD: Daniel Bachovchin

PROVIDER: PXD015047 | Pride | 2019-10-23

REPOSITORIES: Pride

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Dataset's files

Source:

			Action	DRS
	1435AG_S1_1R1_i39_DBachovchin_20190524.raw	Raw
	1435AG_S1_2R1_i39_DBachovchin_20190524.raw	Raw
	1435AG_S1_3R1_i39_DBachovchin_10190524.raw	Raw
	TMT_IP-MS_results.xlsx	Xlsx

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Publications

DPP9's Enzymatic Activity and Not Its Binding to CARD8 Inhibits Inflammasome Activation.

Griswold Andrew R AR Ball Daniel P DP Bhattacharjee Abir A Chui Ashley J AJ Rao Sahana D SD Taabazuing Cornelius Y CY Bachovchin Daniel A DA

ACS chemical biology 20190920 11

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 ...[more]

PMID: 31525884

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Project description:The cellular stress response plays a vital role in regulating homeostasis by modulating cell survival and death. Stress granules (referred to as SGs) are cytoplasmic compartments that allow cells to survive various stressors. Defects in SG assembly and disassembly have been found to play important roles in neurodegenerative diseases, antiviral responses and cancer1–5. Inflammasomes are multi-protein heteromeric complexes that sense intracellular pathogen- and damage-associated molecular patterns and assemble into cytosolic compartments called ASC specks to facilitate caspase-1 (CASP1) activation. This activation of inflammasomes induces secretion of the leaderless proinflammatory cytokines IL-1β and IL-18 and also drives cell fate towards pyroptosis, a form of programmed inflammatory cell death that plays major role in health and disease6–12. Cellular stress sensing can trigger both SGs and inflammasomes; however, they drive contrasting cell fate decisions during stress conditions. Crosstalk between SGs and inflammasomes to decide cell fate has not been well studied. Here we show that the induction of SGs specifically inhibits NLRP3 inflammasome activation, ASC speck formation and pyroptosis. The SG protein DDX3X interacts with NLRP3 to drive inflammasome activation in the absence of SGs. Assembly of SGs leads to the sequestration of DDX3X to inhibit NLRP3 inflammasome function. SGs and the NLRP3 inflammasome compete for DDX3X molecules to coordinate the activation of innate responses and subsequent cell fate decisions under stress conditions. Induction of SGs or loss of DDX3X in the myeloid compartment leads to decreased production of inflammasome-dependent cytokines in vivo. Our findings suggest that macrophages utilize DDX3X availability to interpret stress signals and choose between pro-survival SGs and pyroptotic ASC specks. Together, our data show the role of DDX3X in driving NLRP3 inflammasome and SG assembly, informing a new rheostat-like mechanistic paradigm for regulating live or die cell fate decisions under stress conditions.