Activation of FGF Signaling Mediates Proliferative and Osteogenic Differences between Neural Crest Derived Frontal and Mesoderm Parietal Derived Bone
Figure 6
FGF-2 induction of the intracellular FGF signaling pathways on FOb and POb cells.
FOb and POb cells harvested from E17.5 mice were cultured in serum free α-MEM for 12 hours in presence of specific inhibitors of the FGF signaling pathways to pre-empty endogenous FGF-2 activity. Then cells were treated with 20 ng/ml of rhFGF-2. A, effect of exogenous FGF-2 and inhibitors of MAPK signaling pathway. FGF-2 stimulation for 30 minutes increased phosphorylation of ERK protein equally in FOb and POb cells. Co-treatment with 10 µM U0126 inhibitor inhibited the FGF-2 induction as well as the endogenous phosphorylation of pERK protein in untreated FGF-2 FOb and POb cells. Histogram represents densitometric analysis of electrophoresis bands as above. B, effect of exogenous FGF-2 and inhibitors of PI3K signaling pathway. FGF-2 treatment resulted in increased pAkt phosphorylation which was two fold higher in POb cells compared to FOb cells. Treatment with 20 µM LY294002 inhibitor mostly abrogated the effect of exogenous FGF-2 and drastically reduced the endogenous level of pAkt protein in untreated FGF-2 FOb cells. Histogram represents densitometric analysis of electrophoresis bands. C, effect of exogenous FGF-2 and inhibitors of PKC α/β signaling pathway. FGF-2 treatment also induced an increased phosphorylation of PKC α/β proteins which was inhibited by co-treatment with 2 µM GÖ6983 inhibitor. Treatment with the inhibitor also reduced the endogenous level of p PKC α/β proteins in untreated FGF-2 cells. Histogram represents densitometric analysis of electrophoresis bands. D, effect of exogenous FGF-2 and inhibitors of PKC δ signaling pathway. FGF-2 and/or inhibitor treatments on PKC δ protein produced a similar effect to that observed on PKC α/β proteins. Asterisk * represents statistical significance (*p<0.05).