Distinct endocytotic pathways in epidermal growth factor-stimulated human carcinoma A431 cells

M. A. West, M. S. Bretscher, C. Watts

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    392 Citations (Scopus)

    Abstract

    Addition of EGF to human epidermoid carcinoma A431 cells increases the rate of fluid-phase pinocytosis 6-10-fold as measured by horseradish peroxidase uptake (Haigler, H.T., J.A. McKanna, and S. Cohen. 1979. J. Cell Biol. 83:82-90). We show here that in the absence of extracellular Na+ or in the presence of amiloride the stimulation of pinocytosis by EGF is substantially reduced. Amiloride had no effect on the endocytosis of EGF itself or of transferrin, demonstrating that the receptor-mediated endocytotic pathway operated normally under conditions that blocked stimulated pinocytosis. Amiloride blocked EGF-stimulated pinocytosis in both HCO3--containing and HCO3--free media. The EGF-stimulated pinocytotic activity can frequently be localized to areas of the cell where membrane spreading and ruffling are taking place. These results demonstrate that (a) EGF induces a distinct amiloride-sensitive endocytotic pathway on A431 cells; (b) occupied EGF receptors do not utilize this pathway for their own entry; (c) endocytosis of occupied EGF receptors is not in itself sufficient to stimulate pinocytosis.

    Original languageEnglish
    Pages (from-to)2731-2739
    Number of pages9
    JournalJournal of Cell Biology
    Volume109
    Issue number6 I
    DOIs
    Publication statusPublished - 1989

    ASJC Scopus subject areas

    • Cell Biology

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