Figure 4.

Effects of microtubule integrity on Rab11a and Rab25 distribution in Rab25-overexpressing MDCK cells. MDCK cells stably overexpressing Rab25 were grown on permeable filters and treated with either (A) 33 μM nocodazole for 2 h at 4°C or (B) 5 μM taxol for 4 h at 37°C. Cells were fixed in 4% paraformaldehyde and triple-stained with antibodies against Rab11a, Rab25, and ZO-1. Top panels in both A and B show maximum intensity projection reconstructions of 40 (0.3 μm each) confocal X–Y optical sections. Arrowheads at right indicate the region used to construct X–Z projections shown in the bottom panels. In A, nocodazole treatment dispersed both the Rab11a and Rab25 staining vesicles throughout the cytoplasm with some concentration at the lateral and apical surfaces. In B, taxol caused the redistribution of both Rab11a and Rab25 immunoreactivity to the region of the tight junctions. Rab11a and Rab25 immunoreactivity codistributed in taxol-treated cells. Bar, 4 μm.