Circ_0005526 contributes to interleukin-1β-induced chondrocyte injury in osteoarthritis via upregulating transcription factor 4 by interacting with miR-142-5p.

Circular RNAs (circRNAs) can regulate the progression of osteoarthritis (OA) via serving as competing endogenous RNAs (ceRNAs). This work was performed for functional research of circ_0005526 in Interleukin-1β (IL-1β)-induced OA injury. Circ_0005526, microRNA-142-5p (miR-142-5p) or transcription factor 4 (TCF4) expression was measured via reverse transcription-quantitative polymerase chain reaction assay. Cell analysis was performed by Cell Counting Kit-8 assay for cell viability, EdU assay for cell proliferation and flow cytometry for cell apoptosis. The protein level detection was conducted using western blot. Target analysis was carried out via dual-luciferase reporter assay and RNA pull-down assay. Circ_0005526 was upregulated in OA cartilage tissues and IL-1β-exposed chondrocyte cells. IL-1β inhibited cell viability and proliferation but enhanced cell apoptosis and inflammation, then these damages were attenuated after downregulation of circ_0005526. Circ_0005526 interacted with miR-142-5p, and circ_0005526 knockdown suppressed IL-1β-induced OA progression through upregulating miR-142-5p. TCF4 was regulated by circ_0005526 via targeting miR-142-5p. The function of circ_0005526 was also achieved by upregulation of TCF4. These results unraveled that circ_0005526 promoted IL-1β-induced chondrocyte injury in OA via suppressing miR-142-5p binding to TCF4.