Glucose Regulated Stress Response in ARPE – 19 Cells

Abstract

Among patients with diabetes, many are affected with diabetic retinopathy (DR), a disease affecting their vision and causing blindness. DR is defined as a microvascular complication of diabetes, which leads to secondary damage and degeneration of blood vessels inside the retina. Both Type 1 and Type 2 diabetics are at risk for developing DR. It is well known that neovascularization is the cause of diabetic retinopathy and most investigations have examined endothelial damage. We hypothesized that oxidative stress changes the concentration and localization of stress proteins in retinal pigmented epithelial cells. We used a retinal pigment epithelium cell line known as ARPE-19. The expression of several gene products that are altered under stress conditions were assessed under high (30mM) and low (5mM) glucose conditions. Four different proteins (Grp78, Gp96, ATF4, and Orp150) were assessed by western blot and confocal microscopy. The western blot results were consistent with the preliminary results for Grp78 and Gp96. Specifically, Grp78 showed interesting western blot results as it increased significantly in concentration in low glucose conditions compared to high glucose. The Grp78 protein changed location within the cells under different culture conditions; with high glucose Grp78 was found in the nucleus and with low glucose Grp78 was found in the cytosol. These data show that glucose-induced oxidative stress induces stress protein changes in retinal pigmented epithelium. This is of high significance as it can potentially show that oxidative stress plays a role in the pathogenesis of DR. Targeting treatment of DR to retinal pigmented epithelium may have improved efficacy in diabetic patients.