NLRP3 phosphorylation in its LRR domain critically regulates inflammasome assembly

Nlrp3 inflammasome activation requires Nek7 recruitment to drive ASC speck formation. Here the authors show how Nlrp3 phosphorylation events control this Nek7 recruitment. NLRP3 controls the secretion of inflammatory cytokines IL-1 beta/18 and pyroptosis by assembling the inflammasome. Upon coordinated priming and activation stimuli, NLRP3 recruits NEK7 within hetero-oligomers that nucleate ASC and caspase-1 filaments, but the apical molecular mechanisms underlying inflammasome assembly remain elusive. Here we show that NEK7 recruitment to NLRP3 is controlled by the phosphorylation status of NLRP3 S803 located within the interaction surface, in which NLRP3 S803 is phosphorylated upon priming and later dephosphorylated upon activation. Phosphomimetic substitutions of S803 abolish NEK7 recruitment and inflammasome activity in macrophages in vitro and in vivo. In addition, NLRP3-NEK7 binding is also essential for NLRP3 deubiquitination by BRCC3 and subsequently inflammasome assembly, with NLRP3 phosphomimetic mutants showing enhanced ubiquitination and degradation than wildtype NLRP3. Finally, we identify CSNK1A1 as the kinase targeting NLRP3 S803. Our findings thus reveal NLRP3 S803 phosphorylation status as a druggable apical molecular mechanism controlling inflammasome assembly.

Automated summary

Activation of Nlrp3 inflammasome requires recruitment of Nek7 for ASC speck formation. The phosphorylation status of NLRP3 S803 controls this recruitment, playing a crucial role in inflammasome assembly. These findings suggest that targeting NLRP3 S803 phosphorylation may be a potential strategy for controlling inflammasome-related inflammatory responses.