title: The epidermal growth factor-induced calcium signal in A431 cells.
abstract: Addition of epidermal growth factor (EGF) to human A431 cells causes a 2-4-fold increase in cytoplasmic free Ca2+ concentration ([Ca2+]i) as measured by quin-2 fluorescence. The EGF effect is rapid but transient: [Ca2+]i reaches a maximum within 30-60 s and then returns to its resting value (182 +/- 3 nM) over a 5-8-min period. The EGF-induced [Ca2+]i rise is completely dependent on extracellular Ca2+, is abolished by La3+ and Mn2+, and is not accompanied by changes in membrane potential (mean values of -64 mV). Serum also elicits a transient [Ca2+]i rise in A431 cells, but this response is not dependent on the presence of extracellular Ca2+. The tumor promoter 12-O-tetradecanoylphorbol 13-acetate completely inhibits the EGF- and serum-induced increases in [Ca2+]i without affecting basal [Ca2+]i levels. Our results, together with previous 45Ca2+ uptake data (Sawyer, S. T., and Cohen, S. (1981) Biochemistry 20, 6280-6286), suggest that while serum factors trigger the release of Ca2+ from internal stores, EGF acts by opening a voltage-independent Ca2+ channel in the plasma membrane. The data further suggest a role for protein kinase C in attenuating the Ca2+-mobilizing mechanisms of EGF and serum.
mesh_terms: D000634:Aminoquinolines; D001769:Blood; D002118:Calcium / Q000378:metabolism* / Q000494:pharmacology; D002294:Carcinoma, Squamous Cell / Q000378:metabolism*; D002460:Cell Line; D004815:Epidermal Growth Factor / Q000494:pharmacology*; D006801:Humans; D007811:Lanthanum / Q000494:pharmacology; D008345:Manganese / Q000494:pharmacology; D008433:Mathematics; D008564:Membrane Potentials / Q000187:drug effects; D011188:Potassium / Q000494:pharmacology; D011493:Protein Kinase C / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
chemical_list: D000634:Aminoquinolines; D008345:Manganese; D004815:Epidermal Growth Factor; D007811:Lanthanum; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate; C035739:Quin2; D011188:Potassium; D002118:Calcium