Reciprocal regulation by estradiol 17-beta of ezrin and cadherin-catenin complexes in pituitary GH3 cells

The antiestrogen, ICI 182780, and estradiol-17β (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 β-catenin levels and induced a redistribution of p120^ctn to the cytoplasm. In GH₃ transfectants overexpressing E-cadherin, E₂ had no effect on adhesiveness or on E-cadherin and p120^ctn 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.