Fig. 6.

OxPLs impair LRP6-mediated signaling pathways in bone marrow MSCs. a Human bone marrow MSCs were treated with control conditioned medium or Wnt3a conditioned medium containing vehicle or oxLDL as indicated. Protein extract of the cells was subjected to western blot using antibodies to phosphorylated LRP6 (pLRP6), β-catenin or β-actin. b MSCs were treated with vehicle or 50 nmol·L^-1 PTH together with individual lipids as indicated (nLDL and oxLDL were 20 μg·mL^-1; POVPC and PGPC were 10 μmol·L^-1) for 1 h. Protein extracts of the cells were subjected to Western blot using antibodies to phosphorylated CREB or total CREB. c MSCs were treated with vehicle or 50 nM PTH together with individual lipids as indicated (nLDL and oxLDL were 20 μg·mL^-1l; POVPC, PGPC, and LysoPC were 10 μmol·L^-1) for 1 h. cAMP produced by the cells was detected. n = 6, data are represented as mean ± s.e.m. *P< 0.05, **P < 0.01 vs. PTH + Vehicle group, as determined by Student’s t-tests. d, e Human bone marrow MSCs were treated with BMP2 and/or 20 µg·mL^-1 oxLDL as indicated. Protein extract of the cells was subjected to western blot using antibodies to pSmad1 or total Smad1 (d). RT-qPCR analysis of RUNX2 and osterix mRNA in MSCs treated with 50 ng·mL^-1l BMP4 and/or 20 µg·mL^-1l oxLDL as indicated (e). f, g MSCs were cultured in osteogenic medium with individual lipids as indicated (nLDL and oxLDL were 20 μg·mL^-1; POVPC and PGPC were 10 μmol·L^-1). Cells were fixed and stained with Alizarin red S 21 days after treatment. Representative images were shown in f. Relative intensity of the Alizarin red staining in each group was normalized to the level of control group (g)