AMF-R Tubules Concentrate in a Pericentriolar Microtubule Domain After MSV Transformation of Epithelial MDCK CellsIvan R. Nabia, Ginette Guaya, and Danièle Simardaa Département d'Anatomie, Université de Montréal, Montréal, Québec, Canada Correspondence to: Ivan R. Nabi, Département dAnatomie, Université de Montréal, Pavillon principal, R-816, 2900 Edouard Montpetit, Montréal, Québec, Canada H3T 1J4. Autocrine motility factor receptor (AMF-R) is localized to an intracellular microtubule-associated membranous organelle, the AMF-R tubule. In well-spread untransformed MDCK epithelial cells, the microtubules originate from a broad perinuclear region and AMF-R tubules extend throughout the cytoplasm of the cells. In Moloney sarcoma virus (mos)-transformed MDCK (MSV-MDCK) cells, microtubules accumulate around the centrosome, forming a microtubule domain rich in stabilized detyrosinated microtubules. AMF-R tubules are quantitatively associated with this pericentriolar microtubule domain and the rough endoplasmic reticulum and lysosomes also co-distribute with the pericentriolar mass of microtubules. The Golgi apparatus is closely associated with the microtubule organizing center (MTOC) within the juxtanuclear mass of AMF-R tubules, and no co-localization of AMF-R tubules with the Golgi marker ß-COP could be detected by confocal microscopy. After nocodazole treatment and washout, microtubule nucleation occurs exclusively at the centrosome of MSV-MDCK cells, and only after microtubule extension to the cell periphery does the microtubule cytoskeleton reorganize to generate the pericentriolar microtubule domain after 30-60 min. AMF-R tubules dispersed by nocodazole treatment concentrate in the pericentriolar region in parallel with the reorganization of the microtubule cytoskeleton. MSV transformation of epithelial MDCK cells results in the stabilization of a pericentriolar microtubule domain responsible for the concentration and polarized distribution of AMF-R tubules. (J Histochem Cytochem 45:1351-1363, 1997) Key Words: autocrine motility factor receptor, epithelial transformation, microtubule cytoskeleton, membrane tubule, Madin-Darby canine kidney
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