MiR-497-5p promotes osteogenic/odontogenic differentiation of stem cells from the apical papilla by regulation of the TGF-β Smad pathway through Smurf2

Purpose: To study the influence of miR-497-5p on osteogenic/odontogenic differentiation (OOD) of SCAP, and the signal route involved. Methods: Four groups were set up: miR-497-5p overexpression group (OEG), overexpression control OEC), miR-497-5p inhibition group, and inhibition control group. Alkaline phosphatase (ALP) activity was assayed, and calcified nodules measured. Protein expression levels of dentine salivary phosphoprotein (DSPP), collagen type I, ALP, osteoblast-related factors (Runx2, OSX and OPN) were also assayed. The mRNA expression levels of osteogenesis/dentin-related genes were determined. Results: ALP activity was significantly higher in miR-497-5p overexpression cells than in control, but was reduced, relative to inhibition control group (p < 0.05). The miR-497-5p OEG had significantly more calcified nodules than OEC (p < 0.05). There were markedly up-regulated protein expressions in cells of miR-497-5p OEG than in OCG. Furthermore, protein expressions of Smad2, Smad3 and Smad4 in cells of miR-497-5p OEG were significantly up-regulated, relative to those in OEC, but wer lower in miR-497- 5p inhibitory cells than in inhibitory cells. Conclusion: MiR-497-5p enhances the OOD of SCAP via a mechanism involving TGF-β Smad pathway and Smurf2. Thus, Mir-497-5p may be used as a target for OOD-related drugs.