Zirconium Ions Up-Regulate the BMP/SMAD Signaling Pathway and Promote the Proliferation and Differentiation of Human Osteoblasts
Figure 5
Zirconium ions elevate protein levels in the BMP/SMAD signaling pathway.
(A) Western blotting was used to determine the expression levels of BMP2, SMAD1 and phospho-SMAD1/5 (p-SMAD1/5) in primary HOBs treated with ZrO(NO3)2 and ZrCl4 for 7 days. β-actin was used as the loading control. (B) Quantification of Bmp2 protein bands indicated ZrO(NO3)2 at 500 µM increased Bmp2 protein level compared to the untreated and NaNO3 controls. Compared to the controls, ZrCl4 treatment increased BMP2 at the concentrations of 5 and 50 µM, but not at 500 µM. (C) Treatment of HOBs with ZrO(NO3)2 at 50 and 500 µM increased SMAD1 protein expression, but SMAD1 levels were reduced at 5 µM, compared to the controls. ZrCl4 treatment increased SMAD1 protein level at 5 and 50 µM but not 500 µM. (D) Both ZrO(NO3)2 and ZrCl4 treatment significantly and dose dependently increased the p-SMAD1/5 levels in HOBs. *p<0.05, **p<0.01 vs control.