The p110α and p110β isoforms of class I phosphatidylinositol 3-kinase are involved in toll-like receptor 5 signaling in epithelial cells.

Sabine M Ivison, Mohammed A S Khan, Nicholas R Graham, Leila A Shobab, Yu Yao, Arnawaz Kifayet, Laura M Sly, Theodore S Steiner

Index: Mediators Inflamm. 2010 , (2010)

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Abstract

Bacterial flagellin triggers inflammation in mammalian cells via Toll-like receptor (TLR) 5. Release of the chemokine IL-8 in response to flagellin involves NF-κB, p38 MAP kinase, and phosphatidylinositol 3-kinase (PI3K). However, PI3K has been reported to be either pro- or anti-inflammatory in different model systems. We hypothesized that this could be due to different activities of the p110α and β isoforms of PI3K.PI3K and Akt were rapidly activated in Caco-2 colon carcinoma cells by flagellin. Using a plasmid-based shRNA delivery system and novel p110 isoform-specific inhibitors, we found that flagellin-induced IL-8 production was dependent on both p110α and p110β. However in the mouse, inhibition of p110β but not p110α reduced the increase of serum IL-6 levels induced by intraperitoneal injection of flagellin.These data demonstrate that the p110α and β isoforms of class IA PI3K are both required for the proinflammatory response to flagellin.