The intracellular movement of endocytic vesicles in cultured granulosa cells.
Ligand binding to cell surface receptors induces rapid internalization of ligand-receptor complexes by receptor mediated endocytosis. We have examined the intracellular movement of endocytic vesicles, induced by the lectin concanavalin A (Con A), in cultured rat ovarian granulosa cells using fluorescence and electron microscopy. Within 20 minutes of ligand treatment at 37 degrees C, numerous Con A-containing endocytic vesicles form, which migrate to the cell center by 60 minutes. Double label fluorescence microscopy, using fluorescein-Con-A and rhodamine immunofluorescent staining of tubulin or vimentin, indicates that during vesicle migration microtubules and 10-nm filaments are altered in their organization. By 30 minutes, vesicles are associated with microtubule bundles, which subsequently collapse around the nucleus. Similarly, 10-nm filaments accumulate around the nucleus in conjunction with the perinuclear aggregation of endocytic vesicles. Electron microscopy of Con A-horseradish peroxidase-labeled cells demonstrates that endocytic vesicles fuse to form large receptosome-like structures during intracellular migration and these structures are associated with cytoplasmic microtubules and 10-nm filaments. Taxol, a drug that stabilizes microtubules, prevents endocytic vesicle translocation to the Golgi region. Nocodazole, which causes microtubule disassembly, results in the collapse of 10-nm filaments and the central aggregation of endocytic vesicles. The data indicate that the cytoskeleton participates in the directed intracellular movement of endocytic vesicles; the possible subcellular basis for this movement is discussed.
D000470:Alkaloids / Q000494:pharmacology; D000818:Animals; D001562:Benzimidazoles / Q000494:pharmacology; D002478:Cells, Cultured; D003208:Concanavalin A / Q000378:metabolism; D003599:Cytoskeleton / Q000502:physiology; D004705:Endocytosis; D005260:Female; D006107:Granulosa Cells / Q000502:physiology*; D008870:Microtubules / Q000502:physiology; D015739:Nocodazole; D017239:Paclitaxel; D051381:Rats; D011952:Receptors, Concanavalin A / Q000502:physiology
D000470:Alkaloids; D001562:Benzimidazoles; D011952:Receptors, Concanavalin A; D003208:Concanavalin A; D017239:Paclitaxel; D015739:Nocodazole