Abstract:

Objective To investigate the effect of up-regulation of microRNA-31 （miRNA-31） on the osteogenic differentiation of dental pulp stem cells （DPSCs）， and to elucidate its possible mechanism. Methods The DPSCs in logarithmic growth phase were divided into control group （no treatment）， NC group （transfected with random sequence control）， Agomir group （transfected with miR-31 mimic agomiR-31）， and combination group （transfected with miR-31 mimic agomiR-31 and added with XAV939）. After 48 h of transfection， real-time fluorescence quantitative PCR （RT-qPCR） was used to detect the expression levels of miR-31 in the DPSCs in various groups. MTT assay was used to detect the proliferation abilities of the DPSCs in various groups. Alizarin red staining was used to detect calcium deposition in the DPSCs in various groups. Alkaline phosphatase （ALP） staining was used to detect the degree of osteogenic differentiation of the DPSCs in various groups. Western blotting method was used to detect the expression levels of proteins related to the wingless-type MMTV integration site family（Wnt）/β-catenin signaling pathway in the DPSCs in various groups. Results There were no significant differences in the miR-31 expression level， the cell proliferation abilities at 24， 48 and 72 h， the ratio of calcified region， and the ALP ability between control group and NC group （P>0.05）. Compared with control group and NC group， the expression level of miR-31， the cell proliferation abilities at 24， 48 and 72 h， the ratio of calcified region， and the ALP activity in the DPSCs in Agomir group were increased （P<0.05）. Compared with Agomir group， the expression level of miR-31， the cell proliferation abilities at 24， 48 and 72 h， the ratio of calcified region， and the ALP activity in the DPSCs in combination group were decreased （P<0.05）. There were no significant difference in the expression levels of glycogen synthase kinase 3β （GSK-3β）， β-catenin and Runt-associated transcription factor 2 （Runx2） in the DPSCs between control group and NC group （P>0.05）. Compared with control group and NC group， the expression level of GSK-3β protein in the DPSCs in Agomir group was decreased （P<0.05）， and the expression levels of β-catenin and Runx2 proteins in the DPSCs were increased （P<0.05）. Compared with Agomir group， the expression level of GSK-3β protein in the DPSCs in combination group was increased （P<0.05）， while the expression levels of β-catenin and Runx2 proteins were decreased （P<0.05）. Conclusion Up-regulation of miR-31 can promote the proliferation and osteogenic differentiation of DPSCs， and its mechanism may be related to the activation of Wnt/β-catenin signaling pathway.

Key words: MicroRNA-31, Dental pulp stem cells, Osteogenic differentiation, Cell proliferation, β-catenin