A Novel Tyrosine Kinase Axis in Innate Immune Signaling.

Tyrosine phosphorylation has emerged as a central regulatory mechanism in innate immunity. Building on our recent studies that Syk and EGFR sequentially phosphorylate TLR9 to fully activate it, we discuss how similar mechanisms operate across other Toll-like receptors and the cytosolic DNA sensor STING. Evidence from complementary systems reveals that receptor and nonreceptor tyrosine kinases, including Src-family kinases, Syk, BTK, and EGFR, form an integrated signaling network that triggers receptor activation, trafficking, and downstream gene expression. Scavenger receptors such as SR-A further drive this kinase cascade by coordinating viral recognition to TLR activation. These observations reveal a novel 'tyrosine kinase axis' that connects nucleic acid sensing to spatially controlled innate immune signaling and highlight new opportunities to modulate innate immunity through tyrosine kinase regulation.