Nrf2 mediates the antioxidant effect of DJ‐1 in the kidney

Abstract

Dopamine D2 receptor (D2R) dysfunction is associated with increased oxidative stress in the kidney & high blood pressure. We have reported that DJ‐1 is regulated by D2R in the kidney. Nrf2 is a transcription factor that regulates the expression of several antioxidant genes. We hypothesize that Nrf2 is involved in the DJ‐1‐mediated regulation of ROS production in the kidney. Nrf2 activity was assessed by the expression of its prototypic target genes NQO1, and GST Yc‐2. Silencing DJ‐1 expression in mouse renal proximal tubule cells (mRPTCs) via DJ‐1 siRNA decrease the expression of DJ‐1 (75±15%, n=4, P<0.01), NQO1 (75±15%, n=4, P<0.01), GST Yc‐2 (61±8%, n=4, P<0.05), and Nrf2 (63±11%, n=3, P<0.01). Selective renal silencing of DJ‐1 in mice by the renal subcapsular infusion of DJ‐1 siRNA decreases expression of DJ‐1 (31±5.9%, n=3, P<0.01), NQO1 (46±11%, n=3, P<0.01), GST Yc2 (28±7%, n=3, P<0.05), and Nrf2 (57±6%). the promoter activity of NRF2 in mRPTCs was decreased when DJ‐1 expression was silenced(58%±1, n=5, P<0.01). Silencing of D2R expression also decreased NRF2 promoter activity (53%±2, n=5, P<0.01). Quinpirole a D2R agonist, decreases ROS in mRPTCs but does not modify the mRNA expression of Nrf2 or DJ‐1, or Nrf2 promoter activity. However in the presence of H2O2, silencing DJ‐1 increased ROS production (190.3%±33 vs control, n=6) and the effect is blocked by pretreated with quinpirole (111,1%%±10 vs control, n=6). Our results suggest that DJ‐1 can inhibit renal ROS production via the activation of antioxidant genes mediated by Nrf2, the antioxidant effect of D2R could be independent of DJ‐1 Nrf2, however, D2R is necessary for normal NRF2 and DJ‐1 activity.