Role of basal calcium in the EGF activation of MAP kinases.
The role of intracellular Ca2+ pools in the regulation of growth factor signal transduction pathways and mitogenesis is not well understood. We have examined the roles of basal and transiently mobilized Ca2+ in the regulation of MAP kinases by EGF. To assess the influence of Ca2+ transients we utilized Plcg1-/- and Plcg1+/+ mouse embryonic fibroblasts, while BAPTA/AM was employed to chelate total intracellular Ca2+ in the same cell lines. The MAP kinases erk-1, erk-2 and erk-5 exhibited similar patterns of activation in wild-type and Plcg1-/- cells treated with EGF. However, pretreatment with BAPTA/AM significantly increased and prolonged erk-1 and erk-2 activation in both cell types. In contrast, BAPTA/AM prevented the EGF activation of erk-5 in wild-type and Plcg1-/- cells. These data indicate that basal Ca2+, but not growth factor provoked Ca2+ transients, has a significant influence on the activation of these MAP kinases. AG1478, a specific EGF receptor kinase inhibitor, abolished the prolonged erk-1 and erk-2 activation produced by EGF in cells pretreated with BAPTA/AM. This indicates that the prolonged activation of erk-1 and erk-2 produced in the presence of BAPTA/AM requires continuous signaling from the EGF receptor kinase.
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Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146, USA.
Carpenter
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D000818:Animals; D002118:Calcium / Q000502:physiology*; D002460:Cell Line; D002614:Chelating Agents / Q000494:pharmacology; D004533:Egtazic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004815:Epidermal Growth Factor / Q000378:metabolism* / Q000494:pharmacology; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D051966:Phospholipase C gamma; D017027:Protein Tyrosine Phosphatases / Q000037:antagonists & inhibitors; D011799:Quinazolines; D010738:Type C Phospholipases / Q000235:genetics / Q000378:metabolism*; D020032:Tyrphostins / Q000494:pharmacology
D002614:Chelating Agents; D004791:Enzyme Inhibitors; D007527:Isoenzymes; D011799:Quinazolines; D020032:Tyrphostins; C101044:RTKI cpd; D004533:Egtazic Acid; D004815:Epidermal Growth Factor; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D017027:Protein Tyrosine Phosphatases; D010738:Type C Phospholipases; D051966:Phospholipase C gamma; C025603:1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid; D002118:Calcium