title: The Nck-interacting kinase phosphorylates ERM proteins for formation of lamellipodium by growth factors.
abstract: The mammalian Ste20-like Nck-interacting kinase (NIK) and its orthologs Misshapen in Drosophila and Mig-15 in Caenorhabditis elegans have a conserved function in regulating cell morphology, although through poorly understood mechanisms. We report two previously unrecognized actions of NIK: regulation of lamellipodium formation by growth factors and phosphorylation of the ERM proteins ezrin, radixin, and moesin. ERM proteins regulate cell morphology and plasma membrane dynamics by reversibly anchoring actin filaments to integral plasma membrane proteins. In vitro assays show that NIK interacts directly with ERM proteins, binding their N termini and phosphorylating a conserved C-terminal threonine. In cells, NIK and phosphorylated ERM proteins localize at the distal margins of lamellipodia, and NIK activity is necessary for phosphorylation of ERM proteins induced by EGF and PDGF, but not by thrombin. Lamellipodium extension in response to growth factors is inhibited in cells expressing a kinase-inactive NIK, suppressed for NIK expression with siRNA oligonucleotides, or expressing ezrin T567A that cannot be phosphorylated. These data suggest that direct phosphorylation of ERM proteins by NIK constitutes a signaling mechanism controlling growth factor-induced membrane protrusion and cell morphology.
authors.affiliation: Department of Cell and Tissue Biology, University of California, San Francisco, CA 94143, USA.
authors.forename: Martin
authors.initials: M
authors.lastname: Baumgartner
authors.forename: Amy L
authors.initials: AL
authors.lastname: Sillman
authors.forename: Elizabeth M
authors.initials: EM
authors.lastname: Blackwood
authors.forename: Jyoti
authors.initials: J
authors.lastname: Srivastava
authors.forename: Nikki
authors.initials: N
authors.lastname: Madson
authors.forename: James W
authors.initials: JW
authors.lastname: Schilling
authors.forename: Jocelyn H
authors.initials: JH
authors.lastname: Wright
authors.forename: Diane L
authors.initials: DL
authors.lastname: Barber
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D003598:Cytoskeletal Proteins / Q000737:chemistry / Q000378:metabolism*; D004815:Epidermal Growth Factor / Q000494:pharmacology; D006133:Growth Substances / Q000494:pharmacology*; D066298:In Vitro Techniques; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism*; D051379:Mice; D008840:Microfilament Proteins / Q000737:chemistry / Q000378:metabolism*; D018715:Microscopy, Video; D015513:Oncogene Proteins / Q000737:chemistry / Q000378:metabolism*; D010766:Phosphorylation; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology; D011485:Protein Binding; D011554:Pseudopodia / Q000187:drug effects* / Q000502:physiology; D000099149:Ezrin
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D003598:Cytoskeletal Proteins; D004815:Epidermal Growth Factor; D006133:Growth Substances; D008565:Membrane Proteins; D008840:Microfilament Proteins; D015513:Oncogene Proteins; D010982:Platelet-Derived Growth Factor; D000099149:Ezrin; C078332:Nck protein; C075278:platelet-derived growth factor A; C071058:moesin; C071776:radixin