title: Protein kinase C-mediated feed back inhibition of the Ca2+ response at the EGF receptor.
abstract: Activation of the EGF receptor in A431 cells induces the hydrolysis of phosphoinositides and a transient rise of the cytosolic Ca2+ concentration, [Ca2+]i, which are completely inhibited by acute pretreatment with activators of protein kinase C, such as phorbol esters. Down regulation of the enzyme (by long-term pretreatment of the cells with phorbol esters) causes the [Ca2+]i response to EGF to increase in magnitude and, especially, to become much more persistent (average t1/2 of [Ca2+]i decline 9 min with respect to 2.3 min in controls). These results demonstrate that the activation of protein kinase C induced by EGF in intact A431 cells is sufficient to trigger a feed back, autolimitative regulation of the EGF receptor that might play a prominent physiological role in the definition of the mitogenic activity of the growth factor.
mesh_terms: D002118:Calcium / Q000378:metabolism*; D002294:Carcinoma, Squamous Cell / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D004815:Epidermal Growth Factor / Q000494:pharmacology; D066246:ErbB Receptors / Q000502:physiology*; D005246:Feedback; D007295:Inositol Phosphates / Q000378:metabolism; D007700:Kinetics; D015240:Phorbol 12,13-Dibutyrate; D010703:Phorbol Esters / Q000494:pharmacology; D011493:Protein Kinase C / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014407:Tumor Cells, Cultured
chemical_list: D007295:Inositol Phosphates; D010703:Phorbol Esters; D015240:Phorbol 12,13-Dibutyrate; D004815:Epidermal Growth Factor; D066246:ErbB Receptors; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium