title: Reduction of epidermal growth factor receptor affinity by heterologous ligands: evidence for a mechanism involving the breakdown of phosphoinositides and the activation of protein kinase C.
abstract: The tetradecapeptide bombesin converts epidermal growth factor (EGF) receptors on Swiss 3T3 cells from a high affinity state (KD = 9.8 X 10(-11)M) to a lower affinity state (KD = 1.8 X 10(-9)M). This conversion occurs when the cells are incubated with bombesin at 37 degrees C but not when incubated at 4 degrees C. Previously, a number of other (chemically unrelated) cell growth-promoting peptides and polypeptides have been shown to induce a similar indirect, temperature-dependent reduction of EGF receptor affinity. We have now demonstrated that hormones and growth factors which cross-regulate EGF receptor affinity in Swiss 3T3 cells have a common ability to stimulate the breakdown of phosphoinositides in these cells. We propose that the reduction of EGF receptor affinity is a consequence of the activation of protein kinase C by the diacylglycerol generated by this breakdown. In support of this proposal we have found that exogenously added diacylglycerol reduces the affinity of the Swiss 3T3 cell EGF receptor.
mesh_terms: D000818:Animals; D001839:Bombesin / Q000494:pharmacology; D002478:Cells, Cultured; D004075:Diglycerides / Q000494:pharmacology; D004789:Enzyme Activation; D004815:Epidermal Growth Factor / Q000378:metabolism*; D066246:ErbB Receptors; D007700:Kinetics; D051379:Mice; D008954:Models, Biological; D010716:Phosphatidylinositols / Q000378:metabolism*; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology; D011493:Protein Kinase C; D011494:Protein Kinases / Q000378:metabolism*; D011956:Receptors, Cell Surface / Q000187:drug effects / Q000378:metabolism*; D014667:Vasopressins / Q000494:pharmacology
chemical_list: D004075:Diglycerides; D010716:Phosphatidylinositols; D010982:Platelet-Derived Growth Factor; D011956:Receptors, Cell Surface; D014667:Vasopressins; D004815:Epidermal Growth Factor; C038237:1-oleoyl-2-acetylglycerol; D011494:Protein Kinases; D066246:ErbB Receptors; D011493:Protein Kinase C; D001839:Bombesin