Columbianadin targets TRIM7 to maintain P2X7 palmitoylation, inhibiting cuproptosis in synovial M2 macrophages.

BACKGROUND

Traumatic synovitis often arises from sports injuries, and early intervention is crucial for preserving joint health. Columbianadin (CBN), a natural phytochemical, has demonstrated efficacy in inhibiting inflammatory progression through Chinese herbal injection therapy; however, its underlying mechanism remains unclear.

PURPOSE: This study aims to investigate the molecular mechanism by which CBN maintains P2X7 palmitoylation, characterize TRIM7 as a novel cuproptosis-alert protein, and provide a theoretical foundation for the bench-to-bedside translation of CBN in treating traumatic synovitis.

METHODS

A non-destructive anterior cruciate ligament tear model was established to induce knee joint instability in mice. TRIM7 conditional knockout mice were generated via tissue-specific gene knockout. Single-cell sequencing and bioinformatics analysis were used to screen and validate CBN targets and downstream signaling pathways. Subcellular localization changes of P2X7 were detected via fluorescence co-localization. Copper concentrations in cells and tissues were measured using inductively coupled plasma-mass spectrometry. Palmitoylation levels of P2X7 were analyzed via acyl-biotin exchange assay.

RESULTS

CBN effectively suppressed synovial inflammation in mice. Mechanistically, CBN directly bound to TRIM7 and downregulated its expression. TRIM7 knockout significantly attenuated CBN's anti-inflammatory effects. TRIM7 competed with P2X7 for binding to ZDHHC5, leading to ubiquitination-mediated degradation of ZDHHC5. This disrupted ZDHHC5-dependent palmitoylation of P2X7, preventing its membrane localization and subsequent copper efflux. Accumulated intracellular copper induced cuproptosis.

CONCLUSION

CBN directly targets TRIM7 to preserve ZDHHC5-mediated P2X7 palmitoylation, thereby inhibiting M2 macrophage cuproptosis in synovial tissues. These findings provide a theoretical basis for developing precision drug delivery systems targeting traumatic synovitis.