Reciprocal Regulation by Estradiol 17-beta of Ezrin and Cadherin-catenin Complexes in Pituitary GH3 Cells

The antiestrogen, ICI 182780, and estradiol-17beta (E2) regulate cadherin-mediated cell adhesion in pituitary GH3 cells. Using a cDNA expression array to screen for E2-regulated genes that are associated with the cytoskeleton, we observed that E2 stimulated ezrin gene expression and confirmed that ezrin gene expression is regulated pretranslationally by ICI 182780 versus E2. E2 increased ezrin protein levels in whole-cell lysates and in the cytoskeletal-associated, detergent-insoluble fraction. Confocal microscopy revealed that ezrin was associated with free apical membranes of E2-treated cells. E2 decreased N-cadherin and beta-catenin levels and induced a redistribution of p120ctn to the cytoplasm. In GH3 transfectants overexpressing E-cadherin, E2 had no effect on adhesiveness or on E-cadherin and p120ctn distribution, but increased levels of active ezrin. Ezrin was concentrated at free and apical membranes. These studies provide the first demonstration of the regulation of ezrin by E2 and show that the ER signaling pathway coordinately regulates two cytoskeletal-associated protein complexes, with mutually exclusive cellular distributions, in a reciprocal manner. These findings indicate that E2 enriches the cell membrane with ezrin-membrane protein complexes by both increasing ezrin expression and by enlarging the relative area of nonadhesive membrane to which ezrin is targeted.