Cyclic AMP response element mediates dexamethasone induced suppression of prostaglandin H synthase-2 gene expression in human amnion derived WISH cells.

A human PGHS-2 promoter fragment (300 BP) linked to the luciferase reporter was used to study the regulation of PGHS-2 gene expression in human amnion-derived WISH cells. A cyclic AMP (cAMP) response element (CRE) was found to be important in the induction of PGHS-2 gene expression. This was demonstrated by showing that coexpression of CREB stimulated native but not CRE mutant promoter and that IL-1beta and PMA induced less activity with the mutant promoter as compared to the native promoter. The effect of dexamethasone on IL-1beta and PMA induced promoter activities was further examined. IL-1beta or PMA induced activity was blocked by dexamethasone, whereas IL-1beta or PMA induced mutant activity was not responsive to dexamethasone. Direct activation of CRE by a cAMP elevating agent, isoproterenol, was found to be inhibited significantly dexamethasone. These results suggest that CRE may mediate the induction of PGHS-2 by IL-1beta and PMA as well as the suppression of expression by dexamethasone in amnion-derived cells.