| |
Volume1 Issue 6 June 2000
Apical and basolateral endocytic pathways of MDCK cells meet in acidic common endosomes distinct from a nearly-neutral apical recycling endosome
Exing Wang, Paul S. Brown, Benjamin Aroeti, Steven J. Chapin, Keith E. Mostov and Kenneth W. Dunn
A - Stereopair projections of cells fixed after incubation with TxR-Tf (red) and OG-IgA (green) for 5 minutes show that Tf and IgA are extensively colocal in medial endosomes. B - Stereopair projections of cells fixed after incubation with OG-IgA and TxR-Tf for 15 minutes show that by 15 minutes, while the two probes are still colocal in medial endosomes, much of the IgA is now sorted to apical compartments lacking Tf.
3-dimensional distribution of TxR-Tf and OG-IgA internalized basolaterally and Cy5-IgA internalized apically for 15 minutes. A. Stereopair projection showing distribution of apically internalized Cy5-IgA (pseudocolored green) and basolaterally internalized TxR-Tf (red). IgA and Tf are colocal in medial endosomes, while IgA is enriched in apical endosomes lacking Tf. B. Stereopair projection of the same field as A, but showing combination of apically internalized Cy5-IgA (pseudocolored green) and basolaterally internalized OG-IgA (pseudocolored red). The two probes are extensively proportionally colocal in endosomes throughout the cell. C. Stereopair of cells labeled for 15 minutes with basolateral OG-IgA (green), with apical Cy5-IgA (red) included for the last 5 minutes. At this early time point, apical IgA has labeled medial endosomes containing basolateral IgA, but has not yet reached the ARE, which contains basolateral IgA alone. D. Stereopair projection of cells treated for 60 minutes incubation with 33 mM nocodazole then labeled for 30 minutes with apical Alexa488-IgA (green) and basolateral TxR-IgA (red) in the continued presence of nocodazole. Microtubule depolymerization locks IgA to regions adjacent to the plasma membrane domain from which it is internalized. Note that these stereopairs are also represented as movies of rotated projections on the website located at http://renal.nephrology.iupui.edu/wangetal. Scale bars were omitted from this figure as they interfere with stereo image formation. Panels A, B and D are 27 microns in height, C is 40 microns in height.
|
|
