Targeting cullin 3 by miR-601 activates Nrf2 signaling to protect retinal pigment epithelium cells from hydrogen peroxide.

Activation of Nrf2 cascade can protect retinal pigment epithelium (RPE) cells from hydrogen peroxide (H2O2) and other oxidative injury. The current study identified microRNA-601 (miR-601) as a novel cullin 3 (Cul3)-targeting miRNA that activates Nrf2 cascade. In ARPE-19 cells and primary human RPE cells, forced overexpression of miR-601 significantly inhibited Cul3 3'-UTR activity and downregulated Cul3 mRNA/protein expression, leading to Nrf2 protein stabilization and its nuclear translocation as well as expression of anti-oxidant response elements (ARE)-dependent genes (HO1, NQO1 and GCLC). H2O2 treatment increased miR-601 levels in RPE cells. Significantly, ectopic miR-601 overexpression attenuated H2O2-induced oxidative injury and apoptosis in RPE cells. In contrast, miR-601 inhibition promoted Cul3 expression, lowered basal Nrf2 activation, and enhanced H2O2-induced oxidative stress and apoptosis in RPE cells. In ARPE-19 cells, CRISPC/Cas9-mediated knockout (KO) of Cul3 or Keap1 not only mimicked, but also nullified, miR-601-inudced anti-H2O2 actions. Furthermore, Nrf2 silencing by targeted shRNAs abolished miR-601-inudced cytoprotection in H2O2-treated ARPE-19 cells. Taken together, we show that miR-601 activates Nrf2 signaling to protect RPE cells from H2O2 by targeting Cul3.