OGT promotes the ferroptosis of chondrocytes in osteoarthritis development via O-GlcNAcylation modification of ACSF2.

Osteoarthritis (OA) is a chronic degenerative joint disease that imposes a substantial economic burden on patients and society. The aim of this study was to investigate the effects of O-linked N-acetylglucosamine transferase (OGT) and OGT-mediated O-GlcNAcylation on cartilage injury and chondrocyte ferroptosis in OA. An OA model was established using mice for the in vivo study. Lipopolysaccharide (LPS)-induced chondrocytes were used as a cell model for the in vitro study. RNA and protein expressions were detected using RT-qPCR and Western blotting, respectively. Co-immunoprecipitation (Co-IP) was performed to investigate protein-protein interactions. Lipid reactive oxygen species (ROS) were detected via flow cytometry. Levels of Fe²⁺, glutathione (GSH), lipid peroxidation products (LPO), and malondialdehyde (MDA) were assessed using commercial kits. Cell proliferation and death were evaluated using CCK-8 assays and propidium iodide (PI) staining, respectively. The results indicated that total O-GlcNAcylation and OGT levels were increased in OA models. Inhibition and silencing of OGT suppressed LPS-induced chondrocyte injury. OGT mediated the O-GlcNAcylation of Acyl-CoA Synthetase Family Member 2 (ACSF2), enhancing its stability. O-GlcNAcylation at serine 385 (S385) of ACSF2 mediated its effect on promoting ferroptosis. Additionally, conditional knockout of OGT alleviated OA injury in mice. We demonstrated that OGT mediates OA progression both in vitro and in vivo. Mechanistically, OGT-induced O-GlcNAcylation of ACSF2 at S385 mediates chondrocyte ferroptosis.