Effects of glucagon-like peptide-1 on the free fatty acid-induced expression of pancreatic derived factor in cultured β-TC3 cell line

Abstract

To investigate the effects of FFA(free fatty acid)on the expression of PANDER (pancreatic derived factor) in β-cells and to explore the possible relationship between PANDER and Akt signaling pathway at the anti-apoptotic effects of GLP-1 (glucagon-like peptide-1). β-TC3 cells were cultured in vitro with palmitic acid (PA) of different concentrations and different time courses. The expression of PANDER mRNA was analyzed by realtime quantitative PCR (polymerase chain reaction). β-TC3 cells were cultured with vehicle, 0.5 mmol/L PA, 0.5mmol/L PA + 10nmol/L GLP-1 and 10nmol/L GLP-1 respectively with or without Akti-1/2, a selective inhibitor of Akt, for 12 hours. The protein levels of PANDER, p-Akt and pro-caspase3 were detected by Western blot. And cell apoptosis was analyzed by Hoechst33258 staining. (1) PA could dose and time dependently increased the expression of PANDER mRNA in β cells (vs. control, P < 0.05); (2) PA increased the PANDER protein expression [(148 ± 18)% vs control 100%, P < 0.05)]. However, these effects were attenuated by GLP-1 [(70 ± 17)% vs PA group, P < 0.01]; (3) Akt inhibitor-1/2 alleviated the effects of GLP-1 on PA inducing the expression of PANDER. The expression of PANDER increased significantly in PA + GLP-1 + Akti-1/2 group [(249 ± 49)% vs PA + GLP-1 group (110 ± 54)%, P < 0.01], and cell apoptosis increased significantly as well [(37.8 ± 1.5)% vs PA + GLP-1 group (20.1 ± 3.5)%, P < 0.01]. PA induces the expression of PANDER and the apoptosis of β cell while GLP-1 counteracts the above effects through an activation of Akt signaling pathway.