Fig. 3.

Detailed mechanism of circRNAs in OA. CircRNAs are either upregulated or downregulated in OA. The aberrant expressed circRNAs participate in the OA progression through binding to the miRNAs or proteins to interfere the downstream genes. Regulation of circRNAs on OA development involves in the chondrocytes proliferation and apoptosis, ECM metabolism, inflammation, etc. ECM: extracellular matrix, ERG: E26 transformation-specific (ETS)-related gene, HIF-1a: hypoxia-inducible factor-1a, IGF-1R: insulin-like growth factor 1 receptor, MMP-13: matrix metalloproteinase 13, NAMPT: nicotinamide phosphoribosyl transferase