title: Regulation of ezrin localization by Rac1 and PIPK in human epithelial cells.
abstract: Regulation of ezrin and other ERM proteins is not completely understood, but the involvement of Rho GTPases seems crucial. In this work, expression plasmids encoding full-length, deleted or truncated ezrin were constructed and coexpressed with Rac1 GTPase in HeLa human epithelial cells in order to elucidate the mechanisms of ezrin activation and function. We observed induction of actin stress fiber formation by ezrin constructs harboring the F-actin binding site but devoid of sequences required for intra- or intermolecular binding. Stress fiber-inducing ezrin mutants were localized in adherens junctions containing N-cadherin but no E-cadherin, and also colocalized with F-actin in stress fibers. This localization required the activity of Rac1 and phosphatidylinositol-4-phosphate 5-kinase and involved RhoA. We suggest that localization of ezrin in adherens junctions is regulated by Rac in a manner involving PIPK.
authors.affiliation: Department of Virology, Haartman Institute, University of Helsinki, and HUSLAB Clinical Microbiology, Helsinki University Central Hospital, Helsinki, Finland. eeva.auvinen@helsinki.fi <eeva.auvinen@helsinki.fi>
authors.forename: Eeva
authors.initials: E
authors.lastname: Auvinen
authors.forename: Niina
authors.initials: N
authors.lastname: Kivi
authors.forename: Antti
authors.initials: A
authors.lastname: Vaheri
mesh_terms: D022005:Adherens Junctions / Q000378:metabolism; D003001:Cloning, Molecular; D003598:Cytoskeletal Proteins / Q000235:genetics / Q000378:metabolism*; D004847:Epithelial Cells / Q000378:metabolism*; D017353:Gene Deletion; D006367:HeLa Cells; D006801:Humans; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000502:physiology*; D014018:Tissue Distribution; D014162:Transfection; D020830:rac1 GTP-Binding Protein / Q000378:metabolism / Q000502:physiology*; D020742:rhoA GTP-Binding Protein / Q000502:physiology; D000099149:Ezrin
chemical_list: D003598:Cytoskeletal Proteins; D017853:Phosphotransferases (Alcohol Group Acceptor); D020830:rac1 GTP-Binding Protein; D020742:rhoA GTP-Binding Protein; D000099149:Ezrin; C107953:RAC1 protein, human; C020077:1-phosphatidylinositol-4-phosphate 5-kinase