Fig. 4.
The intracellular apical compartment of nonpolarized EMK1-MDCK cells resembles that of hepatocytic cells. EMK1-MDCK cells maintained either in the presence (control) or absence (EMK1) of doxycycline were cultured in Ca2+-free medium for 12 h to generate contact-naïve monolayers. (A) gp135 colocalization with phalloidin. Confocal x-y and x-z views of permeabilized cells colabeled with anti-gp135 (green) and phalloidin (red). (B and C) gp135 colocalization with dIgA and Tf. PIgR expression in EMK1-MDCK cells was induced with 10 mM sodium butyrate overnight. Human Tf receptor was expressed by adenovirus-mediated gene transfer. Cells were incubated for 2 h with either dIgA (B) or cy3-conjugated Tf (C) before fixation; colocalization between gp135 (green) and dIgA (red; detected with rhodamine-coupled anti-IgA) or gp135 (green) and cy3-Tf (red) is shown in individual confocal x-y sections. (Bars, 10 μm.)