Fig. 4

Sodium butyrate (NaB) inhibited periodontal ligament stem cell (PDLSC) osteogenesis by downregulating Smad1. a Free fatty acid receptor 2 (FFAR2) antagonist (GLPG0974) slightly increased alkaline phosphatase (ALP) activity in NaB-treated cells (compared to the NaB group). b, c GLPG0974 significantly reversed the NaB-mediated inhibition of mineralized nodule formation and the expression of Runx2 and OPN. d–f FFAR2 agonist (4-CMTB) decreased ALP activity, mineralized nodule formation and the expression of Runx2, OCN and OPN in NaB-treated cells. g, h Western blotting and densitometric analysis showed that GLPG0974 reversed the NaB-mediated reduction of Smad1 and p-Smad1/5/8 (compared to the NaB group), while 4-CMTB reduced the the expression of Smad1 and p-Smad1/5/8. The length of the blots was appropriate in the manuscript. i NaB decreased the expression of Smad1 by activating FFAR2, thus reducing the translocation of the p-Smad1/5/8-Smad4 complex into the nucleus, downregulating the expression of Runx2 and OSX, and inhibiting the osteogenic differentiation of PDLSCs. Error bars represent the standard deviation (n = 3). *p < 0.05, **p < 0.01, using one-way ANOVA