Research On Regulatory Mechanism Of PTH On Expression Of OCIL In Rat Osteoblasts

Objective To investigate the effect of regulation of PTH to OCIL(osteoclast inhibitory lectin) gene and multiple signal pathways contribute to the effect in rat UMR106 osteoblast cells.Method To get OCIL mRNA at the specifical point from cultured UMR106 cells in vitro treatment with different concentration PTH(1-34) for 24 hours, or PTH(1-34)(10nM) for 2 to 12 hours, the expression of OCIL mRNA were elvaluted by Quantitative real-time PCR to observe the time- and dose-dependent relationship of PTH to expression of OCIL mRNA. In addition, agonists or inhibitors of signaling pathways treated cells alone or in combination with PTH(1-34) and detected the expression of OCIL mRNA by the same method.Result1. The regulation of RANKL/OPG gene was earlier than OCIL gene in response to PTH; in addition, the expression of OCIL mRNA induced by PTH exhibited both time- and dose-dependent biphasic effects:upregulation after incubated 6h by PTH and to a maximum effect at 24h(P<0.01), or at a dose of 10nM of PTH.2. FSK and db-cAMP. activators of PKA signaling pathway, can upregulate the basal expression of OCIL mRNA 4.2 and 4.5 times respectively when used alone; KT5720 and H89, inhibitors of PKA pathway and both no effect on basal expression of OCIL mRNA, can respectively inhibit PTH-induced expression of OCIL mRNA with the inhibition of 50%(P<0.01),and partically block db-cAMP-mediated OCIL mRNA expression.3. PMA, an activator of PKC, had variable effects on expression of OCIL mRNA when used alone in an apparently time-dependent manner:primarily an significant inhibition effect of 50% after incubated 6h(p<0.01),and then abolished at 12h, but turnover tomodest upregulation after 24h(p<0.01).CHN(chelerythrine),inhibitor of PKC, can upregulate basal expression but not to PTH-induced expression of OCIL mRNA.4. A23187,activator of Calcium signal, can increase the expression of OCIL mRNA and get greatest effect after 6h treated UMR106 cells,5.1 times of control(p <0.01). W7 and KN-62, which both block Calcium signal, could both inhibit PTH-induced expression of OCILmRNA by above 50%.5. PD98059,the MAPK inhibitor, have no effect on basal expression of OCIL mRNA, but it can significantly inhibit PTH-induced expression of OCIL mRNA by about 50% in combination with PTH(P<0.01).6. PD98059 can block the upregulation of expression of OCIL mRNA induced by FSK/db-cAMP when in combination with them respercativly, but no effect on the induced expression of OCIL mRNA by A23187.Conclusions1.PTH(1-34) can upregulate the expression of OCIL mRNA in UMR106 cells in time- and dose-dependent manner:to a maximum effect at a dose of 10nM, or 12h after incubated cells with PTH(1-34).2.Multiple signaling pathways contribute to the induction of PTH to the expression of OCIL mRNA:PKA,MAPK and Caclium signal pathways mediated the expression of OCIL mRNA induced by PTH.