Figure 5: Stable expression of BI-1 in HepG2 cells improves palmitate-induced ER stress and insulin resistance.

(a) Western blot analysis showing effects of BI-1 expression on palmitate-induced ER stress response. Cells were treated with 250 μM palmitate for indicated periods. Stable expression of BI-1 was confirmed with anti-HA, BI-1, and β-actin (as loading control) antibodies (upper). (b) Western blot analysis showing effects of BI-1 expression on palmitate- and insulin-induced ER stress responses. Cells were treated with 250 μM palmitate in presence or absence of insulin. (c,d) Western blot analysis demonstrating effects of BI-1 expression on palmitate-induced insulin resistance. Cells were treated with 250 μM palmitate in presence or absence of insulin. Cell lysates were immunoprecipitated with p-Tyrosine or p-Serine antibody and immunoblotted with antibodies against IRS1/2 (c). Levels of p-Akt, Akt, p-FoxO1, FoxO1, p-GSK3β, and GSK3β are also shown (d). (a) to (d), Representative data performed in three separate measurements.