The p110𝛼 and p110𝛽 Isoforms of Class I Phosphatidylinositol 3-Kinase Are Involved in Toll-Like Receptor 5 Signaling in Epithelial Cells

Figure 2

Flagellin-induced I-κB degradation and NF-κB activation in Caco-2 cells are PI3K independent. (a) I-κB$\alpha$ degradation in Caco-2 cells treated with IL-1$\beta$ (10 ng/ml) or flagellin (FliC, 1000 ng/ml or 500 ng/ml) was not inhibited by LY29 (30 $\mu$M) but was inhibited by Bay 11-7082 (20 $\mu$M). Caco-2 cell lysates were analyzed by Western blot for anti-IκB$\alpha$ and anti-GAPDH and the band density measured. Density of I-κB bands was divided by GAPDH to normalize for protein loading and transfer, and the ratio was taken versus unstimulated cells in each experiment to calculate the amount of I-κB$\alpha$ degradation. Results were pooled from four separate experiments. $P<.01$ versus DMSO by ANOVA, DMSO + FliC versus Bay11 + FliC. (b) NF-κB activation in Caco-2 cells measured by electrophoretic mobility shift assay, with the shifted NF-κB band indicated by the arrow. (c) Densitometry measurements of NF-κB-bound probe bands, pooled from 3 independent experiments.

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