Circ_0138959/miR-495-3p/TRAF6 axis regulates proliferation, wound healing and osteoblastic differentiation of periodontal ligament cells in periodontitis

BACKGROUND/PURPOSE: Periodontitis is a chronic inflammatory disease, and periodontal ligament cells (PDLCs) are pivotal for osteogenesis. Circular RNAs (circRNAs) can regulate disease progression via targeting miRNA/mRNA axis. The purposes of this study were to explore the function and mechanism of circ_0138959 in periodontitis. MATERIALS AND METHODS: Periodontitis cell model was established by lipopolysaccharide (LPS) treatment in PDLCs. RNA expression was determined by quantitative reverse transcription-polymerase chain reaction assay. Cell proliferation was detected using 3-(4, 5-dimethylthiazol-2-y1)-2, 5-diphenyl tetrazolium bromide assay. Wound healing and cell apoptosis were examined by wound healing assay and flow cytometry. Inflammatory cytokines were measured via Enzyme-linked immunosorbent assay. Osteogenic differentiation was assessed by Alkaline phosphatase and Alizarin red S staining assays. Western blot was used for protein detection. The target interaction was validated by dual-luciferase reporter assay. RESULTS: Circ_0138959 was overexpressed in periodontitis tissues and LPS-treated PDLCs. Downregulation of circ_0138959 attenuated LPS-induced inhibition of proliferation, wound healing and osteogenic differentiation but promotion of apoptosis and inflammation. Circ_0138959 acted as a miR-495-3p sponge, and the regulatory role of circ_0138959 in LPS-induced cell injury was achieved by sponging miR-495-3p. Additionally, miR-495-3p targeted TNF Receptor Associated Factor 6 (TRAF6) and miR-495-3p protected against LPS-induced cell dysfunction by targeting TRAF6. Circ_0138959 upregulated TRAF6 level via inhibiting miR-495-3p. CONCLUSION: This study suggested that circ_0138959 upregulated the TRAF6 expression by binding to miR-495-3p, consequently aggravating LPS-induced cell damages in PDLCs. Circ_0138959 might be a probable target for treatment of periodontitis.