[Expression of Osterix mRNA and protein induced by recombinant human bone morphogenetic protein-2 in human...

To detect the changes of Osterix (Osx) mRNA and protein expression in human periodontal ligament cells (HPDLCs) induced by recombinant human bone morphogenetic protein-2 (rhBMP-2), and examine the role of BMP-2 and Osx during the osteogenic differentiation of HPDLCs.

HPDLCs were isolated and cultured in vitro with explant method. Cells at passage 3 were cultured in DMEM with rhBMP-2 at different concentrations (50, 100, 150, 200, 250, 300, 400, and 600 µg/L) for different times (2, 3, 5, 7, 10, 14 and 21 days). Then the expressions of Osx mRNA and protein were measured by real-time reverse transcription (RT)-PCR and Western blotting respectively. Cells were treated with 10 µmol/L SB203580 (p38 inhibitor) to inhibit p38 phosphorylation induced by rhBMP-2. The mineralization nodules formation and the expressions of phosphorylated p38 and Osx mRNA were detected respectively.

During the culture of rhBMP-2, the expression of Osx mRNA significantly increased. Initially Osx protein had a low expression and then increased in a time-dependent manner followed by the production of bone-like nodules in HPDLCs. Under the effect of SB203580, the up-regulation of phosphorylated p38 expression induced by rhBMP-2 was significantly inhibited as well as the expression of Osx (Osx mRNA expression: 0.378 ± 0.034 vs 0.134 ± 0.027, Osx protein expression: 0.353 ± 0.024 vs 0.155 ± 0.031, both P < 0.01). Meanwhile the mineralization nodules formed by HPDLCs induced by rhBMP-2 were fewer and delayed.

BMP-2 has a significant positive regulatory role on the expression of Osx in HPDLCs. And p38 pathway is an important link of this regulatory process. Thus, as an important signaling pathway in osteogenic differentiation of HPDLCs, BMP-2/p38/Osx may be involved in periodontal tissue remodeling.