Antioxidant taurine inhibits chondrocyte ferroptosis through upregulation of OGT/Gpx4 signaling in osteoarthritis induced by anterior cruciate ligament transection

OBJECTIVE: The aim of this study was to investigate the potential molecular mechanisms by which taurine protects against cartilage degeneration. METHODS: The anterior cruciate ligament transection (ACLT) surgery was used to construct an animal model of osteoarthritis (OA). Metabolomics was used to identify characteristic metabolites in osteoarthritic chondrocytes. Transcriptomics and metabolomics were used to explore potential mechanisms by which the small molecule metabolite taurine protects against inflammatory chondrocyte damage. Cell transfection and small molecule inhibitors/agonists were used to validate the molecular mechanisms by which taurine protects inflammatory chondrocytes in vitro. Finally, adeno-associated virus and small molecule inhibitors/agonists were used to validate the molecular mechanisms by which taurine protects against cartilage degeneration in vivo. RESULTS: Metabolomic assays identified taurine as a possible key metabolic molecule in the progression of OA. Transcriptomics and metabolomics revealed that O-GlcNAc transferase (OGT)-dependent O-GlcNAcylation and Gpx4-dependent ferroptosis may mediate the inflammatory protective effects of taurine on chondrocytes, which was further confirmed by gain and loss of function in vitro. Subsequently, further experiments indicated that the possible existence of a direct binding site for Gpx4 and OGT proteins, which provides evidence for the presence of O-GlcNAc modification of Gpx4 protein. Finnaly, we demonstrated that Gpx4-dependent ferroptosis and OGT-dependent O-GlcNAcylation may be potential mechanisms by which taurine protects against cartilage degeneration in vivo. CONCLUSION: Antioxidant taurine inhibits chondrocyte ferroptosis through upregulation of OGT/Gpx4 signaling. Supplementation with taurine, a safe nonessential amino acid, may be a potential therapeutic strategy for OA.