title: Regulation of the ligand-dependent activation of the epidermal growth factor receptor by calmodulin.
abstract: Calmodulin (CaM) is the major component of calcium signaling pathways mediating the action of various effectors. Transient increases in the intracellular calcium level triggered by a variety of stimuli lead to the formation of Ca(2+)/CaM complexes, which interact with and activate target proteins. In the present study the role of Ca(2+)/CaM in the regulation of the ligand-dependent activation of the epidermal growth factor receptor (EGFR) has been examined in living cells. We show that addition of different cell permeable CaM antagonists to cultured cells or loading cells with a Ca(2+) chelator inhibited ligand-dependent EGFR auto(trans)phosphorylation. This occurred also in the presence of inhibitors of protein kinase C, CaM-dependent protein kinase II and calcineurin, which are known Ca(2+)- and/or Ca(2+)/CaM-dependent EGFR regulators, pointing to a direct effect of Ca(2+)/CaM on the receptor. Furthermore, we demonstrate that down-regulation of CaM in conditional CaM knock out cells stably transfected with the human EGFR decreased its ligand-dependent phosphorylation. Substitution of six basic amino acid residues within the CaM-binding domain (CaM-BD) of the EGFR by alanine resulted in a decreased phosphorylation of the receptor and of its downstream substrate phospholipase Cγ1. These results support the hypothesis that Ca(2+)/CaM regulates the EGFR activity by directly interacting with the CaM-BD of the receptor located at its cytosolic juxtamembrane region.
authors.affiliation: Instituto de Investigaciones Biomédicas, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, Arturo Duperier 4, E-28029 Madrid, Spain.
authors.forename: Hongbing
authors.initials: H
authors.lastname: Li
authors.forename: Svetlana
authors.initials: S
authors.lastname: Panina
authors.forename: Amandeep
authors.initials: A
authors.lastname: Kaur
authors.forename: María J
authors.initials: MJ
authors.lastname: Ruano
authors.forename: Pablo
authors.initials: P
authors.lastname: Sánchez-González
authors.forename: Jonas M
authors.initials: JM
authors.lastname: la Cour
authors.forename: Alexander
authors.initials: A
authors.lastname: Stephan
authors.forename: Uffe H
authors.initials: UH
authors.lastname: Olesen
authors.forename: Martin W
authors.initials: MW
authors.lastname: Berchtold
authors.forename: Antonio
authors.initials: A
authors.lastname: Villalobo
mesh_terms: D000818:Animals; D019703:Calcineurin / Q000235:genetics / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2 / Q000235:genetics / Q000378:metabolism; D002147:Calmodulin / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D066246:ErbB Receptors / Q000819:agonists / Q000235:genetics / Q000378:metabolism*; D055785:Gene Knockdown Techniques; D006801:Humans; D051379:Mice; D051966:Phospholipase C gamma / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation / Q000502:physiology
chemical_list: D002147:Calmodulin; C512478:EGFR protein, human; C541485:EGFR protein, mouse; D066246:ErbB Receptors; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D019703:Calcineurin; D051966:Phospholipase C gamma; D002118:Calcium