Expression and function of osteogenic genes runt-related transcription factor 2 and osterix in orthodontic tooth movement in rats.

OBJECTIVE To investigate the expression and function of osteogenic genes osterix (OSX) and runt-related transcription factor 2 (RUNX2) in the rat periodontal tissues under orthodontic force for the remodeling of the periodontal tissues. METHODS 24 Wistar rats were randomly divided into 4 groups of orthodontic tooth movements for 1, 3, and 7 days (experimental groups) and control group (without orthodontic force). The expression of RUNX2 and OSX in the periodontal tissues was analyzed using real time PCR for mRNA and Western blot analysis for protein. The data were also analyzed for involvement of the two genes in signal pathways using bioinformatics tools. RESULTS The mRNA levels of RUNX2 and OSX increased in the periodontal tissues after subjected to the orthodontic force for 1 to 7 days, with the highest level occurring at day 7. The relative expression levels of RUNX2 and OSX mRNA were 1.85 ± 0.12, 304 ± 0.06 and 4.16 ± 0.068, and 1.52 ± 0.09, 1.83 ± 0.03 and 2.56 ± 0.06 at day 1, 3 and 7, respectively. The results of Western blot analysis were consistent with the mRNA results. CONCLUSION In orthodontic tooth movement, the expression of RUNX2 and OSX was upregulated as a result of external stimulation, suggesting that the two genes is involved in periodontal tissue remodeling and plays an important role in periodontal tissue remodeling.