Role of Bax Protein and Caspase-3 at High Glucose-Induced Apoptosis in Human Embryonic Kidney (HEK) 293 Cells

Hyperglycemia is the principal factor responsible for microvascular complications of diabetes. Diabetic nephropathy is a serious and common complication leading to end stage renal disease. The exact molecular mechanisms of high glucose-induced toxicity on renal cells are still incompletely understood. Therefore in the present study, glucose-induced toxicity was studied in HEK (human embryonic kidney) cells as an in vitro model for diabetic nephropathy. First, the viability of HEK 293 cells exposed to glucose was measured by MTT (Methyl Thiazolyl Tetra-zolium) assay. Caspase-3 activity was determined spectrophotometrically using enzyme specific substrate. Moreover, the alteration in expression of Bax, Bcl2 and caspase-3 were measured by Western blotting. The results showed that high glucose significantly reduced cell viability after 48 h (p<0.05). In Western blot analysis, the ratio of Bax/Bcl-2 protein expression in cells treated with high glucose was significantly increased compared to controls (p<0.001). The activity of caspase-3 was significantly increased in treated cells compared to control (p<0.01). Moreover, high glucose exposure induced a significant decrease in protein level of procaspase-3 (p<0.01), indicating conversion of pro-form into the mature caspase. On the current data, it could be concluded that high glucose can cause HEK cell death, in which apoptosis plays an important role possibly by the mitochondrial pathway through higher expression of Bax pro-apoptotic protein and also by activation of caspase-3 related pathways.