title: Intact microtubules are necessary for complete processing, storage and regulated secretion of von Willebrand factor by endothelial cells.
abstract: The importance of intact microtubules in the processing, storage and regulated secretion of von Willebrand factor (vWf) from Weibel-Palade bodies in endothelial cells was investigated. Human umbilical vein endothelial cells treated for 1 h with colchicine (10(-6) M) or nocodozole (10(-6) M) lost their organized microtubular network. Stimulation of these cells with secretagogues (A23187, thrombin) produced only 30% release of vWf in comparison to control cells containing intact microtubules. The nocodazole treatment was reversible. One-hour incubation in the absence of the drug was sufficient for microtubules to reform and restore the full capacity of the cells to release vWf. Long-term incubation (24 h) of endothelial cells with microtubule-destabilizing agents had a profound effect on vWf distribution. In control cells, vWf was localized to organelles in the perinuclear region (i.e., endoplasmic reticulum and Golgi apparatus) and to Weibel-Palade bodies. In drug-treated cells vWf staining was dispersed throughout the cytoplasm, and Weibel-Palade bodies were absent. The vWf synthesized in the absence of microtubules contained significantly less large multimers than that produced by control cells. Since Weibel-Palade bodies specifically contain the large multimers, we hypothesize that the structural defect in vWf secreted by cells in the absence of microtubules is due to the lack of Weibel-Palade bodies in these cultures.
authors.forename: S
authors.initials: S
authors.lastname: Sinha
authors.forename: D D
authors.initials: DD
authors.lastname: Wagner
mesh_terms: D001562:Benzimidazoles / Q000494:pharmacology; D002478:Cells, Cultured; D003078:Colchicine / Q000494:pharmacology; D004727:Endothelium / Q000378:metabolism*; D005260:Female; D005455:Fluorescent Antibody Technique; D006801:Humans; D008162:Lumicolchicines / Q000494:pharmacology; D008870:Microtubules / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D015739:Nocodazole; D014404:Tubulin / Q000032:analysis; D014471:Umbilical Veins; D014841:von Willebrand Factor / Q000235:genetics / Q000378:metabolism*
chemical_list: D001562:Benzimidazoles; D008162:Lumicolchicines; D014404:Tubulin; D014841:von Willebrand Factor; D015739:Nocodazole; D003078:Colchicine