Influence of colchicine and vinblastine on the intracellular migration of secretory and membrane glycoproteins: III. Inhibition of intracellular migration of membrane glycoproteins in rat intestinal columnar cells and hepatocytes as visualized by light and electron‐microscope radioautography after ³h‐fucose injection

Abstract

In the first paper of this series (Bennett et al., 1984), light-microscope radioautographic studies showed that colchicine or vinblastine inhibited intracellular migration of glycoproteins out of the Golgi region in a variety of cell types. In the present work, the effects of these drugs on migration of membrane glycoproteins have been examined at the ultrastructural level in duodenal villous columnar cells and hepatocytes. Young (40 gm) rats were given a single intravenous injection of colchicine (4.0 mg) or vinblastine (2.0 mg). At 10 min after colchicine and 30 min after vinblastine administration, the rats were injected with 3H-fucose. Control rats received 3H-fucose only. All rats were sacrificed 90 min after 3H-fucose injection and their tissues processed for radioautography. In duodenal villous columnar cells, 3H-fucose labeling of the apical plasma membrane was reduced by 51% after colchicine and by 67% after vinblastine treatment; but there was little change in labeling of the lateral plasma membrane. Labeling of the Golgi apparatus increased. This suggests that labeled glycoproteins destined for the apical plasma membrane were inhibited from leaving the Golgi region, while migration to the lateral plasma membrane was not impaired. In hepatocytes, labeling of the sinusoidal plasma membrane was reduced by 83% after colchicine and by 85% after vinblastine treatment. Labeling of the lateral plasma membrane also decreased, although not so dramatically. Labeling of the Golgi apparatus and neighboring secretory vesicles increased. This indicates that the drugs inhibited migration of membrane glycoproteins from the Golgi region to the various portions of the plasma membrane. Accumulation of secretory vesicles at the sinusoidal front suggests that exocytosis may also have been partially inhibited. In both cell types, microtubules almost completely disappeared after drug treatment. Microtubules may, therefore, be necessary for intracellular transport of membrane glycoproteins, although the possibility of a direct action of these drugs on Golgi or plasma membranes must also be considered.

Traffic through the golgi apparatus as studied by radioautography

“…Exposed 2 months. (Reproduced from Bennett et al, 1984, with permission of the publisher.) x 18,000.…”

The cytoskeleton in development of epithelial cell polarity

“…Pharmacological studies suggest that although not absolutely required, the efficient transport of apically directed membranes in polarized epithelia requires intact MTs (Achler et al, 1989;Bennett et al, 1984;Breitfeld et al, 1990;Hugon et al, 1987;Parczyk et al, 1989). When polarized epithelia are treated with MT-disruptive drugs, there is a decrease in delivery of materials to the apical plasma membrane, although nearly 50% of the materials still reach the apical domain.…”

Synthesis and migration of 3H‐fucose‐labeled glycoproteins in the retinal pigment epithelium of albino rats, as visualized by radioautography

“…The quantitative analysis was carried out on electron micrographs at a final magnification of 17,000 from radioautographs developed by the fine-grain development procedure. This analysis consisted in recording the structures of the pigment epithelial cells localized underneath the silver grains by methods previously described (Bennett et al, 1984a). Fifty to eighty electron micrographs were analyzed for each time interval.…”