MEK1/2 promote ROS production and deubiquitinate NLRP3 independent of ERK1/2 during NLRP3 inflammasome activation

Inflammasomes are cytosolic supramolecular complexes that play a key role in the innate immune response. Overactivation of NLR family pyrin domain containing 3 (NLRP3) inflammasome leads to multiple diseases. Posttranslational modifications (PTMs) are essential modulators of inflammasomes especially in activation phase. Here we found that MEK1/2 kinase activity was indispensable in NLRP3 inflammasome activation both in vitro and in vivo. Inhibition of MEK1/2 resulted in reactive oxygen species (ROS) scavenging and ubiquitination of NLRP3, which further blocked NLRP3 inflammasome activation. These effects were independent of ERK1/2, which were classic downstream of MEK1/2. These investigations proposed a mechanism that MEK1/2 regulated inflammation via non-transcriptional regulation of NLRP3 inflammasome and might help better understanding the effects and side-effects of MEK inhibitors in clinical use.