Circ_0000479 promotes proliferation, invasion, migration and inflammation and inhibits apoptosis of rheumatoid arthritis fibroblast-like synoviocytes via miR-766/FKBP5 axis

Circular RNAs have been demonstrated to play a critical role in the progression of autoimmune diseases. This study aimed to investigate the function of circ_0000479 in rheumatoid arthritis (RA) fibroblast-like synoviocytes (FLSs). Circ_0000479 was found to be upregulated in RA-FLSs. Flow cytometry analysis, cell counting Kit-8, transwell, wound-healing and enzyme-linked immunosorbent assays were conducted to evaluate RA-FLS apoptosis, proliferation, invasion, migration and inflammation. The results confirmed that circ_0000479 knockdown suppressed pathogenic properties of RA-FLSs. Through bioinformatics analysis and screening, we obtained 18 miRNAs that can bind to circ_0000479, of which miR-766 was most significantly up-regulated after circ_0000479 knockdown. MiR-766 was confirmed to be down-regulated in RA-FLSs and the combination between circ_0000479 and miR-766 was verified by dual-luciferase reporter assays. Moreover, the inhibitory effect of circ_0000479 knockdown in RA-FLS progression was attenuated by miR-766 inhibitor. By intersecting the target genes of miR-766 with the up-regulated genes in RA, we obtained 8 genes, of which FKBP5 was most significantly down-regulated after miR-766 overexpression. The results of dual-luciferase reporter assays also verified that FKBP5 was the target gene of miR-766. In addition, FKBP5 overexpression abated the inhibition of RA-FLS progression caused by circ_0000479 silencing. In summary, circ_0000479 binds to miR-766 to promote RA progression via FKBP5.