Fig. 9.

Reduction of insulin signaling by knocking down the insulin receptor prevents development of insulin resistance induced by the prolonged exposure to oleate. The cognate siRNA against the insulin receptor or a scramble siRNA was introduced into hep1c1c7 cells by transient transfection with Lipofectamine 2000 for 36 h, as described in Fig. 7. Cells after knocking down of insulin receptor for 36 h were treated with oleate with sera for 16 h. After an extensive washing with warm PBS, the cells were exposed to 1 nM insulin for 5 min. Activation of Akt was determined by immunoblottings with specific antibodies as indicated. Results represent means ± SE of 3 independent experiments, each in triplicate.