Fig. 3. Expression and activation of PI3K p110 isoforms by bile salts in hepatocytes.
(A) Expression of p110α, β, and γ in rat hepatocytes and Huh7-Ntcp cells was confirmed by immunoblotting. Two different antibodies (Cell Signaling Technologies(C):CS and Santa Cruz(C):SC) were used for p110γ. Rat thymus served as a positive control for p110γ. Rat hepatocyte cultures were stimulated with bile salts at 25 μM (TLC) to 50 μM (TC, TUDCA, GCDC, TCDC) for 15 min, and isoforms-specific lipid kinase assays were performed. Lipid kinase assays after immunoprecipitation of (B) p110α, (C) p110β, and (D) p110γ (mean ± SD, *p <0.05 vs. DMSO, n = 4–6) are shown. Results represent fold increase in formation of the specific PI3K reaction product PIP3 compared to DMSO. (E) Summary of kinase assays: “+” indicates activation of the respective isoform.