Tyrosine phosphorylation of NLRP3 by the Src family kinase Lyn suppresses the activity of the NLRP3 inflammasome.

In response to microbes and other danger signals, the NLRP3 inflammasome in immune cells triggers the activation of the protease caspase-1, which mediates the maturation of the inflammatory cytokine IL-1β. Here, we investigated how the NLRP3 inflammasome is regulated. We found that its activation in primary mouse macrophages induced the Src family kinase Lyn to phosphorylate NLRP3 at Tyr918, which correlated with a subsequent increase in its ubiquitination that facilitated its proteasome-mediated degradation. NLRP3 tyrosine phosphorylation and ubiquitination was abrogated in Lyn-deficient macrophages, which produced increased amounts of IL-1β. Furthermore, mice lacking Lyn were more susceptible to LPS-induced septic shock in an NLRP3-dependent manner. Our data demonstrate that Lyn-mediated tyrosine phosphorylation is a prerequisite for the ubiquitination that dampens NLRP3 inflammasome activity.