[Changes of mRNA and protein levels of activating transcription factor-4 after centrifugal force stimulation in cultured human periodontal ligament cells].

PURPOSE

This study was designed to examine the changes of mRNA and protein levels of activating transcription factor-4 after centrifugal force stimulation in cultured human periodontal ligament (PDL)cells.

METHODS

Human PDL cells were cultured by sequential digestio, and then stimulated by centrifugal force (167g) for 10, 30, 60, 90, 120 and 240 minutes. The changes of mRNA and protein levels of ATF4 were analyzed by semi-quantitative RT-PCR and Western blotting. The data was analyzed with SPSS11.5 software package for ANOVA.

RESULTS

Unstimulated human PDL cells exhibit an ATF4 mRNA expression, but very low level of protein; Immediately 10 minutes after force application, the mRNA and protein levels of ATF4 increased(P>0.05); at 30-minute,the mRNA level increased significantly to a peak level(P<0.01), at 60-minute, the protein level increased significantly to a peak level(P<0.01); at 90-minute, mRNA and protein levels decreased, but still higher than the control(P<0.01); after 120 minutes, mRNA and protein levels decreased to control levels(P>0.05).

CONCLUSION

Centrifugal force stimulates ATF4 gene expression within a narrow time frame: a temporary increase of ATF4 expression and a fast downregulation back to its preloading level. This study demonstrates that ATF4 may play a critical role in orthodontic alveolar bone remodeling.