[Effect of nocodazole on endocytosis of epidermal growth factor receptor].
During endocytosis EGF-receptor complexes are transported from early peripheral endosomes to late juxtranuclear-located endosomes to be then degraded in lysosomes. It is suggested that such a spatial organization of endosomal compartments is maintained by microtubule system and is necessary for lysosomal degradation of endocytosed cargo. In the present work, a study was made of the influence of Nocodazole, a microtubule depolymerizing agent, on endocytosis of fluid phase marker HRP and EGF entering the cell via receptor-mediated endocytosis. By subcellular fractionation in Percoll gradient it was shown that Nocodazole did not affect HRP internalization but stimulated its accumulation in a fraction sedimented together with late endosomes, thus preventing HRP delivery to lysosomes. On the contrary, Nocodazole exerted no influence on dynamics of compartmentalization and lysosomal degradation of EGF-receptor complexes. Moreover, no alterations were found in the functioning of a so well-known EGF-stimulated signal transduction pathway as MAP-kinase cascade. At the same time microtubule depolymerization dramatically changed the morphology of endosomal compartments abolishing juxtranuclear localization of late endosomes. Our data suggest that translocation of EGF-receptor complexes is not necessary for their normal lysosomal processing. Rab7, traditionally considered as a marker of late endosomes, has been found to demonstrate in Nocodazole-treated cells, in contrast to the control, a low extent of co-localization with endosomal structures. It could be supposed that the role of Rab7 is not so much to mediate early-to-late endosome transition as to maintain spatial organization of endosomal apparatus by mediating endosome-cytoskeleton interactions.
Sokolova
I P
IP
Institute of Cytology, Russian Academy of Sciences, St. Petersburg.
Arnautov
A M
AM
Blagoveshchenskaia
A D
AD
Nikol'skiĭ
N N
NN
Kornilova
E S
ES
D016475:3T3 Cells; D000818:Animals; D003102:Colloids; D004705:Endocytosis / Q000502:physiology*; D011992:Endosomes / Q000187:drug effects; D066246:ErbB Receptors / Q000187:drug effects* / Q000378:metabolism; D008247:Lysosomes / Q000187:drug effects; D051379:Mice; D015739:Nocodazole / Q000627:therapeutic use*; D011205:Povidone; D012822:Silicon Dioxide; D013347:Subcellular Fractions / Q000378:metabolism
D003102:Colloids; C016039:Percoll; D012822:Silicon Dioxide; D066246:ErbB Receptors; D011205:Povidone; D015739:Nocodazole
Vliianie nokodazola na éndotsitoz retseptora épidermal'nogo faktora rosta.