DJ-1 protects retinal pericytes against high glucose-induced oxidative stress through the Nrf2 signaling pathway

Oxidative stress has been associated with the etipathogenesis of Diabetic retinopathy (DR). Studies have shown that DJ-1 plays an important role in regulating the reactive oxygen species (ROS) production and resistance to oxidative stress-induced apoptosis. This study aimed to investigate whether DJ-1 upregulates oxidative stress and prevents damage to retinal capillary pericytes by increasing antioxidant capacity through the Nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway. Nrf2 is a redox-sensitive transcription factor that encode antioxidant enzymes and phase II metabolic enzymes, activation of Nrf2 functions is one of the critical defensive mechanisms against oxidative stress in many tissues. Our results showed after DJ-1 overexpression, apoptosis of rat retinal pericytes (RRPs) decreased, the ratio of B-cell lymphoma-2 (Bcl-2) to BCL2-Associated X Protein (BAX) increased, the production of ROS decreased, and the protein expression and activity of manganese superoxide dismutase (MnSOD, also called SOD2) and catalase (CAT) increased. DJ-1 overexpression activated Nrf2 expression, however, after Nrf2 silencing, apoptosis of RRPs increased, the ratio of Bcl-2 to BAX decreased, the production of ROS increased, the protein expression of MnSOD and CAT decreased, and the expression of heme oxygenase-1 (HO-1), NADP(H) quinone oxidoreductase (NQO1), glutamate-cysteine ligase catalytic subunit (GCLC) and modifier subunit (GCLM) decreased. These data suggest that enhancement of the Nrf2 pathway is a potential protective strategy for the treatment of DR. Therefore, DJ-1 may prevent high glucose-induced oxidative stress and RRPs apoptosis through the Nrf2 signaling pathway, thereby preventing the early onset and progression of DR.