MiR-28-3p enhances healing of fracture via negative regulation of the target gene Sox6 and activation of PI3K/Akt signaling pathway

Purpose: To investigate the effect of miR-28-3p on fracture healing, and the involvement of Sox6 gene and PI3K/Akt signaling pathway in the process.Methods: Mouse osteoblast cell lines were cultured in vitro, and miR-28-3p over-expression and inhibitory plasmids were separately added to the medium. The corresponding control groups were set up. Real-time quantitative polymerase chain reaction (qRT-PCR) was used to measure the mRNA expressions of the osteogenesis-related genes Col1a1, Col-Ⅱ and Col-X in osteoblasts. The protein expressions of Sox6, Col1a1, Col-Ⅱ, Col-X, PI3K, p-PI3K, Akt and p-Akt in rat cartilage tissue were determined with Western blotting assay.Results: The expression of Sox6 protein in the miR-28-3p over-expression group was significantly reduced, when compared with the miR-28 overexpression control, but Sox6 protein expression in the miR-28-3p inhibition group was significantly increased, relative to inhibition control group (p < 0.05). In the miR-28-3p over-expression and Sox6 over-expression groups, Col1a1 protein expression was significantly increased, while Col-Ⅱ and Col-X protein expressions decreased, when compared with the respective over-expression control group (p < 0.05). Over-expression of miR-28-3p markedly upregulated phosphorylation levels of PI3K and Akt, relative to over-expression control group, while miR-28-3p inhibition significantly downregulated the phosphorylations of PI3K and Akt, relative to the inhibition control group (p < 0.05).Conclusion: Over-expression of miR-28-3p may enhance the healing of fractures by induction of PI3K/Akt signaling route via negative regulation of the expression of Sox6 gene. Keywords: MiR-28-3p, Sox6, PI3K/Akt signaling pathway, Fracture healing