METTL3/YTHDC1 mediates up-regulation of lncRNA OGRU in an m6A-dependent manner involving in oxidative stress and inflammation of HG-induced Müller cells.

Background: Diabetic retinopathy (DR) is a common complication of diabetes, which may cause visual disturbance and even loss of sight. Oxidative stress and inflammation are two crucial pathological factors of DR; however, their specific regulatory mechanisms in DR remain obscure.

Methods: DR models were established in streptozotocin-challenged rats and high glucose (HG)-stimulated Müller cells. Western blotting and RT-qPCR were performed to determine target molecule levels. ROS release was evaluated by DCFH-DA staining, and the levels of MDA, GSH, SOD, and CAT were detected using commercial kits. The levels of proinflammatory factors (TNF-α, IL-1β, IL-6, MCP-1, and CXCL-1) were analyzed by RT-qPCR and ELISA. The subcellular localization of OGRU was observed by FISH. Molecular interaction was evaluated by RIP. M6A level was assessed by MeRIP and colorimetric quantification kit.

Results: HG stimulation or diabetic stress resulted in an elevation in the overall m6A level, as well as expression level of methyltransferase-like 3 (METTL3) in the experimental models of DR. M6A writer METTL3 stabilized lncRNA OGRU via m6A modification. Functionally, METTL3 deficiency relieved HG-induced oxidative stress damage and inflammation in Müller cells. Rescue assays demonstrated that OGRU overexpression reversed METTL3 silencing-mediated protection against HG-stimulated Müller cells. Furthermore, YTH Domain-Containing Protein 1 (YTHDC1) coordinated with METTL3 to enhance OGRU stability in an m6A-dependent manner.

Conclusion: METTL3-mediated m6A modification stabilized OGRU with assistance of YTHDC1, which led to oxidative stress and inflammation during DR progression. Targeting METTL3/YTHDC1/OGRU axis might be a potential therapeutic strategy for DR.