MiR-539-3p inhibited chondrogenic differentiation in human adipose stem cells by targeting Sox9

Mesenchymal stem cells (MSCs) have emerged as the attractive candidates for cell therapy for cartilage repair in clinical therapy of osteoarthritis (OA). MiR-539-3p was reported to differentially express during chondrogenic differentiation of adipose stem cells (ASCs) by miRNA microarrays. The aim of the study was to investigate the effects and underlying mechanisms of miR-539-3p on chondrogenic differentiation of ASCs.

Human ASCs (hASCs) were obtained from liposuction and transfected with miR-539-3p mimic or inhibitor. Then, the cells were cultured in chondrogenic differentiation medium including transforming growth factor-β1 (TGF-β1).

Our results found that miR-539-3p was gradually down-regulated during chondrogenic differentiation of hASCs. MiR-539-3p overexpression inhibited TGF-β1-induced chondrogenic differentiation of hASCs, as supported by reducing the gene and protein expression of chondrogenic differentiation markers type II collagen alpha 1 (COL2A1), aggrecan (ACAN), and type II collagen. In contrast, miR-539-3p inhibitor significantly promoted the chondrogenic differentiation of hASCs. Dual luciferase reporter assay demonstrated that Sox9 was a direct target gene of miR-539-3p. The expression of SRY-box transcription factor 9 (Sox9) was up-regulated progressively over time during chondrogenic differentiation of hASCs. Additionally, Sox9 overexpression notably reversed chondrogenic differentiation of hASCs inhibited by miR-539-3p mimic, as demonstrated by the decreased expression of COL2A1, ACAN, and type II collagen.

Altogether, miR-539-3p inhibited chondrogenic differentiation of hASCs by targeting Sox9. MiR-539-3p may have significant clinical applications for use as a targeted therapy of OA.