Environmental Estrogens and Regulation of the Prolactin Promoter in Pituitary Cells

Abstract

17 ?-estradiol (E2) is produced primarily by the ovaries and governs gene expression in a number of target tissues, including the brain and pituitary. In the pituitary particularly, the roles of estrogen extends to stimulating reproductive hormone secretion. Estrogen receptor alpha (ER?) is a ligand-inducible transcription factor that mediates the physiological effects of E2. Within a target cell, occupancy of ERs by E2 results in receptor activation and nuclear localization. Subsequent binding to an estrogen response element (ERE) in a target gene allows recruitment of various coregulator proteins which enhance or suppress gene expression. The actions of endogenous E2 can be mimicked by environmental estrogens that are produced in plants (phytoestrogens) or produced commercially as synthetic compounds (xenoestrogens). These studies examine the ability of E2 and environmental estrogens to alter transcriptional activity a pituitary cell line.