Fig 1.

Effect of exendin-4 on ABCA1 expression in rat pancreatic islets and INS-1 cells. (A) Total cell lysate was purified from rat pancreatic islets treated with 10 nM of exendin-4 for 24 hrs. Western blot analysis was performed to examine ABCA1 expression. Expression of GAPDH was studied as the control, and the results are shown in the bottom lanes. The plot shows the ratio of ABCA1/GAPDH. Results are represented as mean ± S.E.M. of three experiments for each treatment group. The asterisk denotes a significant difference (P < 0.01). (B) Exendin-4 increases ABCA1 gene transcription. INS-1 cells were transfected with 1 μg pABCA1-LUC and treated with the indicated concentrations of exendin-4 for 24 hrs prior to cell harvesting. All assays were corrected for β-galactosidase activity, and the total amount of protein in each reaction was identical. The results were expressed as relative luciferase activity compared with that in the control cells arbitrarily set at 100. Each data point shows the mean ± S.E. of four separate transfections that were performed on separate days. The ‘*’ denotes the significant difference (P < 0.01). (C) Effects of the phosphatidylinositol 3-kinase inhibitor LY-294002, the PKC inhibitor bisindolylmaleimide I, PKA inhibitor H-89, and the CaMK inhibitor STO-609 on ABCA1 transcriptional activity in INS-1 cells with 10 nM exendin-4. Vehicle: 0.1% dimethyl sulphoxide. Each data point shows the mean ± S.E. of three separate transfections that were performed on separate days. The asterisk denotes a significant difference (P < 0.01).