Methods: HPDL cells were treated with various concentration of ATP (0-100 µM). The expression of RANKL and OPG were examined by reverse transcription polymerase chain reaction (RT-PCR) and Western analysis. The amount of PGE2 was determined by ELISA. The application of inhibitors was used to examine the mechanism involved.
Results: ATP induced RANKL at both mRNA and protein levels in a dose dependent manner but had no effect on OPG expression. Interestingly, application of indomethacin abolished the increase of RANKL, suggesting the cyclooxygenase (COX)-dependent mechanism. ATP could also induce COX-2 mRNA and PGE2 secretion. The upregulation of COX-2 was inhibited by MRS2179, P2Y1 antagonist.
Conclusions: Extracellular ATP stimulates RANKL expression in HPDL cells through P2Y1 and COX-dependent pathway. The results indicate the significance of ATP in the regulation of RANKL/OPG system in periodontal tissue.
This work is supported by Thailand Research Fund (TRF).