Regulating effect of Circ_ATRNL1 on the promotion of SOX9 expression to promote chondrogenic differentiation of hAMSCs mediated by MiR‐145‐5p

Abstract

Circ_ATRNL1 is significantly highly expressed in cartilage tissues of patients with osteoarthritis. This study explored the role and mechanism of circ_ATRNL1 in cartilage differentiation of human adipose‐derived mesenchymal stem cells (hAMSCs). hAMSCs were isolated and identified by flow cytometry. The degree of chondrocyte and adipogenic differentiation was assessed using Alcian blue staining and Oil Red O staining, respectively. The expressions of cartilage‐ and adipogenic‐related genes, circ_ATRNL1, and SOX9 were detected by reverse transcription quantitative polymerase chain reaction. The correlation between SOX9 and circ_ATRNL1 was analyzed using Pearson test. Bioinformatics and luciferase analysis were used to detect the overlapped target miRNAs of circ_ATRNL1 and SOX9. The role of circ_ATRNL1/miRNA/SOX9 was examined using functional rescue assays. hAMSCs were identified as CD90‐, CD105‐, and CD44‐positive. The degree of cartilage differentiation of hAMSCs was significantly enhanced after 2 weeks. Cartilage‐related genes, circ_ATRNL1 and SOX9, were significantly upregulated, and positively correlated with each other. Circ_ATRNL1 overexpression enhanced hAMSC proliferation and differentiation into chondrogenesis, and promoted the expressions of COL2, Aggrecan, and SOX9. Overexpression of circ_ATRNL1 inhibited the adipogenic differentiation of hAMSCs and the expressions of adipogenic‐related genes. miR‐145‐5p was a target miRNA for circ_ATRNL1 and SOX9. miR‐145‐5p mimic inhibited hAMSC differentiation toward cartilage, and inhibited the expression of cartilage‐related factors. miR‐145‐5p mimic effectively reversed the regulating effect of circ_ATRNL1 on hAMSCs. Circ_ATRNL1 regulates the promotion of SOX9 expression to promote chondrogenic differentiation of hAMSCs mediated by miR‐145‐5p.