Fig. 2.

Nuclear translocation of ZO-1 and ZONAB is induced by E2. Changes in the intracellular localization of ZO-1 (a) and ZONAB (b) proteins were observed when MCF-7 cells were incubated during 1 h, with 1 nM of E2. Signal intensities were quantified, normalized with actin (cytoplasmic fractions; white bars) or histone H1 (nuclear fractions; black bars), and expressed as percent of control groups (Vh; ethanol). In order to show that both ZO-1 and ZONAB proteins are colocalized inside the nuclei, confocal fluorescence digital images were taken in high confluence MCF-7 cells, when incubated with vehicle, E2 alone, or E2 + ICI (ER antagonist). E2 incubation decreases membrane localization of both proteins and increases their concentration inside the nuclei, an effect that was totally precluded by the incubation with ICI. In order to demonstrate nuclear colocalization of ZO-1 (FITC, green labeled) and ZONAB (rhodamine; red labeled), MCF-7 (c) or T47D (d) cancer cells were grown in high confluence and incubated in the absence and presence of 1 nM of E2. All images are representative of at least three different experiments. Original magnifications ×400