Quantitative phosphoproteomic analysis of IL-33 mediated signaling

Interleukin-33 (IL-33) is a novel member of the IL-1 family of cytokines that plays diverse roles in the regulation of immune responses. IL-33 exerts its effects by binding to a heterodimeric receptor complex consisting of interleukin-1 receptor like 1 (IL1RL1) and an accessory receptor protein IL-1RAcP resulting in the production and release of proinflammatory cytokines. A detailed understanding of the signaling pathways activated by IL-33 remains elusive. To elucidate IL-33 mediated signaling, we performed a global quantitative phosphoproteomic analysis using stable isotope labeling by amino acids in cell culture. Employing anti-phosphotyrosine antibodies and titanium dioxide-based enrichment strategies, we identified 6,207 phosphorylation sites mapping to 2,013 phosphoproteins of which more than 185 phosphosites are regulated by IL-33 stimulation. Our findings will greatly expand the understanding of IL-33 signaling and provide novel therapeutic targets for IL-33/IL-33R-associated diseases in humans.