Year: 2021
Type: article
Abstract: NLRP1 and CARD8 are related cytosolic sensors that upon activation form supramolecular signalling complexes known as canonical inflammasomes, resulting in caspase−1 activation, cytokine maturation and/or pyroptotic cell death. NLRP1 and CARD8 use their C-terminal (CT) fragments containing a caspase recruitment domain (CARD) and the UPA (conserved in UNC5, PIDD, and ankyrins) subdomain for self-oligomerization, which in turn form the platform to recruit the inflammasome adaptor ASC (apoptosis-associated speck-like protein containing a CARD) or caspase-1, respectively. Here, we report cryo-EM structures of NLRP1-CT and CARD8-CT assemblies, in which the respective CARDs form central helical filaments that are promoted by oligomerized, but flexibly linked, UPAs surrounding the filaments. Through biochemical and cellular approaches, we demonstrate that the UPA itself reduces the threshold needed for NLRP1-CT and CARD8-CT filament formation and signalling. Structural analyses provide insights on the mode of ASC recruitment by NLRP1-CT and the contrasting direct recruitment of caspase-1 by CARD8-CT. We also discover that subunits in the central NLRP1 CARD filament dimerize with additional exterior CARDs, which roughly doubles its thickness and is unique among all known CARD filaments. Finally, we engineer and determine the structure of an ASC CARD –caspase-1 CARD octamer, which suggests that ASC uses opposing surfaces for NLRP1, versus caspase-1, recruitment. Together these structures capture the architecture and specificity of the active NLRP1 and CARD8 inflammasomes in addition to key heteromeric CARD-CARD interactions governing inflammasome signalling.
Source: Nature Communications
Language: English
Subfield: Molecular Biology
Domain: Life Sciences
Open Access status: gold
Estimated APC paid: $5,560
Funders: U.S. Department of Energy, Oregon Health and Science University, Memorial Sloan-Kettering Cancer Center, National Institutes of Health, Office of Science, University of Massachusetts Medical School, National Cancer Institute, National Institute of General Medical Sciences, National Institute of Allergy and Infectious Diseases, National Center for Advancing Translational Sciences, Biological and Environmental Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development
Awards: G1213529597, SMOCs: Novel Signal Transduction Complexes as New Targets for Drug Discovery, G2051006376, Characterizing the DPP8/9 Pyroptotic Checkpoint with Chemoproteomic Protease Substrate Profiling, G2695487608, G289723095, G3206779478, G3508161151, G4165928844, G4789071022, G5718375046, G5952257446, G6221506569, G6780141363, G7562546725, G7673727097, G7913850483, G9000003249, G9000023522, G9000060489, G9000087684, G9000092162, G9000223883, G9000224218, G9000228610, G9000275082, G9000323527, G9000333842, Cancer Center Support Grant, Characterizing the Mechanism of DPP8/9 Inhibitor-Induced Pyroptosis
OpenAlex ID: W3119851465