Figure 6.

Image analysis of FITC-dextran basolateral uptake in polarized MDCK cells. Control and JAS-pretreated cells were incubated with FITC-dextran present in the basolateral chamber for 15 min. FITC-dextran-labeled structures at the middle region (e.g., see Figure 5, e and f) were separated into two populations according to relative fluorescence intensity measured with SOM software. Small low-intensity endosome clusters (green) and large high-intensity endosome clusters (red) are differentiated in this colored image. Small endosome clusters were present in both control (a) and JAS-treated cells (b), whereas large endosome clusters were clearly more abundant in JAS-treated cells (b). (c) Quantification of relative fluorescence intensities showed that JAS treatment induced an approximately sixfold increase in uptake into the basal region and a significant increase in uptake into the middle region. In control cells, large endosome clusters were present mostly in the middle region, whereas in JAS-treated cells, the number of both types of clusters is significantly increased at the basal and middle regions.