Prostaglandin F(2alpha) stimulates MEK-ERK signalling but decreases the expression of alkaline phosphatase in dental pulp cells.

AIM

To study prostaglandin F(2alpha) (PGF(2alpha)) receptor expression and downstream signalling in cultured human dental pulp cells and the effect of PGF(2alpha) on the alkaline phosphatase (ALP) activity of dental pulp cells.

METHODOLOGY

Human dental pulp cells were cultured and exposed to PGF(2alpha). The expression of PGF(2alpha) (FP) receptors was analysed by reverse transcriptase polymerase chain reaction (RT-PCR) and Western blotting. The activation of extracellular regulated kinase (ERK) and cAMP responsive element binding protein/activating transcription factor-1 (CREB/ATF-1) signalling was determined by Western blotting. The expression of ALP in pulp cells after exposure to PGF(2alpha) was evaluated by ALP staining and PCR.

RESULTS

Dental pulp cells expressed FP receptor mRNA and protein. Exposure to PGF(2alpha) revealed little cytotoxicity to pulp cells. PGF(2alpha) induced both ERK and CREB/ATF-1 phosphorylation in pulp cells. Exposure to PGF(2alpha) (>1 micromol L(-1)) further decreased the ALP activity and mRNA expression. However, U0126 (an inhibitor of MEK1) showed little preventive effect on the decline of ALP activity in dental pulp cells by PGF(2alpha).

CONCLUSION

PGF(2alpha) may potentially activate FP receptors leading to ERK/CREB-ATF-1 activation during its production in inflamed dental pulp. PGF(2alpha) attenuated the ALP activity of pulp cells possibly via pathways not solely by MEK/ERK activation. PGF(2alpha) is a contributing factor of pulpal inflammation by regulating the activities of pulp cells.