Involvement of hypoxia-inducible factor-1α in the oxidative stress induced by advanced glycation end products in murine Leydig cells.

Hyperglycemia increases the formation of advanced glycation end products (AGEs), triggers oxidative impairments and influences inducible factor (HIF)-1α protein levels and transactivation function. Compromised HIF-1α in testis leads to male infertility. The aim of the study was to investigate the role of HIF-1α in oxidative stress induced by AGEs in murine Leydig TM3 cells. TM3 cells were treated with 50 μg/ml of AGEs, or HIF-1α siRNA or 500 μM of DMOG (dimethyloxalylglycine) respectively. The cells were also pretreated with HIF-1α siRNA or 500 μM of DMOG and then were treated with 50 μg/ml of AGEs. The formation of reactive oxygen species (ROS) and cell apoptosis was evaluated. The expression of caspase-3, Heme oxygenase (HO)-1, steroidogenic acute regulatory protein (StAR) and cytochrome P450 17α polypeptide 1 (CYP17A1) was examined by Western blotting. AGEs increased ROS production, induced apoptosis and activated HIF-1α and HO-1 in TM3 cells. HIF-1α attenuated the AGE-induced ROS formation and promoted apoptosis via the upregulation of caspase-3. Knockdown of HIF-1α inhibited the expression of CYP17A1 and StAR, and enhanced the inhibition of StAR and CYP17A1 by AGEs. These findings indicate that attenuated HIF-1α exacerbates the oxidative stress injury by AGEs in murine Leydig cells, and contributes to diabetic male infertility.