NLRP3 cages revealed by full-length mouse NLRP3 structure control pathway activation

Area of Science:

• Cellular Biology
• Immunology
• Structural Biology

Background:

• The NACHT-, leucine-rich-repeat- (LRR), and pyrin domain-containing protein 3 (NLRP3) inflammasome is a key sensor of cellular damage and a therapeutic target for chronic inflammatory diseases.
• NLRP3's precise structure and mechanism of activation at the membrane remain incompletely understood.

Purpose of the Study:

• To elucidate the endogenous, stimulus-responsive structure of full-length mouse NLRP3.
• To investigate the role of NLRP3's oligomeric structure in inflammasome activation and cellular responses.

Main Methods:

• Cryo-electron microscopy to determine the structure of NLRP3 oligomers.
• Structure-guided mutagenesis to probe the function of specific NLRP3 domains and interactions.
• Cell-based assays to assess inflammasome activation, caspase-1 processing, and cell death.

Main Results:

• Identified a 12- to 16-mer double-ring cage structure of full-length mouse NLRP3, predominantly localized to membranes.
• Demonstrated that LRR-LRR interactions stabilize the double-ring, shielding pyrin domains and preventing premature activation.
• Showed that disruption of the double-ring structure impairs trans-Golgi network dispersion, inflammasome punctum formation, caspase-1 processing, and cell death.

Conclusions:

• NLRP3 exists physiologically as a membrane-associated double-ring oligomer poised for activation.
• This oligomeric structure is essential for sensing diverse cellular stress signals and initiating the inflammasome pathway.
• The findings provide critical insights into NLRP3 inflammasome regulation and suggest new therapeutic strategies for inflammatory conditions.