1.The oxindole Syk inhibitor OXSI-2 blocks nigericin-induced inflammasome signaling and pyroptosis independent of potassium efflux.
Yaron JR1, Rao MY2, Gangaraju S2, Zhang L2, Kong X2, Su F2, Tian Y2, Glenn HL2, Meldrum DR3. Biochem Biophys Res Commun. 2016 Apr 8;472(3):545-50. doi: 10.1016/j.bbrc.2016.03.021. Epub 2016 Mar 9.
The inflammasome is a caspase-1-activating complex that is implicated in a growing number of acute and chronic pathologies. Interest has increased in identifying small molecular inhibitors of inflammasome signaling because of its role in clinically relevant diseases. It was recently reported that the protein tyrosine kinase, Syk, regulates pathogen-induced inflammasome signaling by phosphorylating a molecular switch on the adapter protein ASC. However, several aspects of the role of Syk in inflammasome signaling and the effects of its inhibition remain unclear. The aim of the present study is to explore in detail the effects of the oxindole Syk inhibitor OXSI-2 on various aspects of nigericin-induced inflammasome signaling. Our results indicate that OXSI-2 inhibits inflammasome assembly, caspase-1 activation, IL-1β processing and release, mitochondrial ROS generation, and pyroptotic cell death. Using a novel live cell potassium sensor we show that Syk inhibition with OXSI-2 has no effect on potassium efflux kinetics and that blockade of potassium efflux with extracellular potassium alters Syk phosphorylation.