Fig. 4.

PPARγ and PPARα activities regulate osteoblast and osteocyte functions.

(a) Relative mRNA expression of gene markers in isolated osteoblasts from femora endosteal surface. (b) The effect of SR10171 and rosiglitazone on transcriptional activity of TCF/LIF/β-catenin complex measured in U33/γ2 cells transfected with Top-Flash promoter construct and treated for 72 h with tested ligands. (c) Relative mRNA expression of gene markers in isolated osteocytes from femora cortical bone. Expression of Dmp1, E11, and Fgf23, served as a purity control of osteocyte isolates and confirmed equivalent enrichment in all samples analyzed. (d) Relative mRNA expression of Sost, Dkk1, and Rankl in primary osteocytes treated with either 10 μM SR10171, or 1 μM rosiglitazone, or 50 μM WY14643 in ex vivo conditions for 3 days. (e) Protein levels after shRNA knocked-down (KD) of either PPARα or PPARγ. KD was introduced in MLO-A5 cells using lentiviral shRNA constructs. Protein levels of either PPARγ or PPARα were assessed by Western blots, quantitated and normalized to the levels of HSP90, a housekeeping protein. (f) The effect of PPARγ (γKD) or PPARα (αKD) silencing on Sost and Dkk1 gene expression. Data represent the mean ± SD (n = 3 per group, repeated twice). *P < 0.05; **P < 0.01; ***P < 0.001 One Way Anova.