FTO-mediated Nrf2 demethylation alleviates high glucose-induced oxidative stress and apoptosis in retinal pigment epithelial cells

BackgroundN6-methyladenosine (m6A) modification contributes to the development of diabetic retinopathy (DR). This study aimed to reveal the role and downstream regulatory signaling of an m6A demethylase fat mass and obesity-associated gene (FTO) in high glucose-induced damage of retinal pigment epithelial cells.Methods and resultsBy stimulating ARPE-19 cells with different concentrations of glucose (0 mM-50 mM), we observed that FTO expression was significantly downregulated, while m6A modification level was upregulated in a glucose concentration-dependent manner in ARPE-19 cells. Then, ARPE-19 cells were transfected with FTO knockdown or overexpression vector, and administrated with high glucose (25mM) to perform functional verification experiments. FTO overexpression recovered cell viability, inhibited cell apoptosis, elevated GSH/GSSG ratio, but reduced MDA and ROS levels in high glucose-induced cells, while FTO knockdown further exacerbated high glucose-triggered oxidative stress and apoptotic cell death. Additionally, FTO overexpression upregulated the expression of NF-E2-related factor 2 (Nrf2) and activated the antioxidant heme oxygenase 1 (HO-1) signal through m6A demethylation on Nrf2 in high glucose-treated ARPE-19 cells. Finally, we proved that knockdown of Nrf2 or HO-1 reversed the protective effects of FTO overexpression on high glucose-treated ARPE-19 cells.ConclusionAltogether, the study demonstrated that FTO ameliorates high glucose-triggered oxidative stress and cell apoptosis through activating the Nrf2/HO-1 signaling pathway in an m6A-dependent manner.