Fig. 6

Metformin enhanced PDLSC osteogenic differentiation under high glucose via inhibition of the NPR3-mediated MAPK pathway. A Gene expression of C-type natriuretic peptide (CNP) in PDLSCs transfected with or without LV-NPR3 when they were cultured in normal, high glucose, or high glucose with metformin addition (mRNA expression levels detected by qRT-PCR). B Total CNP content in PDLSCs transfected with or without LV-NPR3 when they were cultured in normal, high glucose, or high glucose with metformin addition (total content in the cell culture supernates detected by ELISA). C, D Protein expression of MAPK pathway-related proteins (p38 MAPK, p-p38 MAPK, Erk1/2, p-Erk1/2, JNK, p-JNK) in PDLSCs transfected with or without LV-NPR3 when they were cultured in normal, high glucose, or high glucose with metformin addition (protein expression levels detected by Western blot analysis). The displayed bands were cropped from the corresponding original blots. HG, high glucose. Met, metformin. LV-NPR3, NPR3-overexpression lentivirus. Experiments for P4 cells from three different donors were repeated independently for at least 3 times, and data are presented as the means ± SD (n = 3). p value was based on one-way analysis of variance (one-way ANOVA). *p < 0.05, **p < 0.01, and ***p < 0.001 represent significant differences between the indicated columns, while NS represents no significant difference