Effect of Glucose Metabolism-Associated Protein-1 on Exendin-4-Treated Pancreatic Islet Cell Function

Abstract

Exendin-4 regulates blood sugar. Glucose metabolism-associated protein-1 (GMRP-1) regulates islet cell function. Therefore, this paper intends to analyze the effect of GMRP-1 on Exendin-4treated islet cells. The islet cell MIN6 cells were separated into control group, Exendin-4 group, GMRP-1 overexpressing+ Exendin-4 group, and GMRP-1 siRNA+ Exendin-4 group followed by analysis of the expression of GMRP-1 by quantitative real-time PCR and Western blot, cell proliferation by MTT, cell apoptosis by flow cytometry, Bcl-2, Bax, Fas and Fas-L expression by real-time PCR, as well as caspase-3 activity, reactive oxygen species (ROS) and superoxide dismutase (SOD) activity. Exendin-4 and GMRP-1 overexpression+ Exendin-4 significantly increased GMRP-1 expression and promoted cell proliferation, decreased apoptotic rate and Caspase-3 activity, increased Bcl-2 and Fas-L expression, reduced Fas and Bax expression, as well as decreased ROS generation and increased SOD activity (P < 0 05), and the changes in GMRP-1 overexpression+ Exendin-4 group was more significant (P < 0 01). However, GMRP-1 siRNA+ Exendin-4 group significantly down-regulated GMRP-1 expression, decreased MIN6 cell prolifer- ation, increased cell apoptosis and Caspase-3 activity, decreased Bcl-2 and Fas-L expression, elevated Fas and Bax expression, increased ROS content and decreased SOD activity compared to control group and Exendin-4 group (P < 0 05). Up-regulation of GMRP-1 expression promoted Exendin-4-induced proliferation and inhibited apoptosis of islet cells. Down-regulation of GMRP-1 expression reversed Exendin-4's effect on islet cells.