Palmitoylation of TK1 exacerbates osteoarthritis by promoting JNK-mediated metabolic reprogramming.

Osteoarthritis (OA) lacks approved disease-modifying therapies. Here, by integrating quantitative proteomics with reanalysis of public single-cell RNA sequencing data from human articular cartilage, we identify thymidine kinase 1 (TK1) as a pathogenic regulator linking inflammatory stress to metabolic rewiring and matrix breakdown. TK1 is markedly upregulated in OA chondrocytes. Mechanistically, IL-1β enhances S-palmitoylation of TK1 at Cys153, which promotes USP9X-dependent deubiquitination and prevents proteasomal degradation, leading to TK1 accumulation. Stabilized TK1 acts as a scaffold to potentiate JNK signaling, increase PRMT1 and PFKFB3 expression, drive excessive glycolysis, and accelerate extracellular matrix catabolism. Conversely, the depalmitoylase PPT1 destabilizes TK1 and restrains glycolytic activation. Based on this mechanism, we developed a cell-penetrating interfering peptide, Depalm-WT, which disrupts the TK1-JNK interaction, promotes TK1 depalmitoylation and degradation, and suppresses downstream catabolic responses. In preclinical OA models, Depalm-WT attenuated cartilage degeneration and disease progression. These findings define a palmitoylation-stabilized TK1-JNK-glycolysis axis in OA and support targeted TK1 destabilization as a potential therapeutic strategy.