title: Ezrin is required for efficient Rap1-induced cell spreading.
abstract: The Rap family of small GTPases regulate the adhesion of cells to extracellular matrices. Several Rap-binding proteins have been shown to function as effectors that mediate Rap-induced adhesion. However, little is known regarding the relationships between these effectors, or about other proteins that are downstream of or act in parallel to the effectors. To establish whether an array of effectors was required for Rap-induced cell adhesion and spreading, and to find new components involved in Rap-signal transduction, we performed a small-scale siRNA screen in A549 lung epithelial cells. Of the Rap effectors tested, only Radil blocked Rap-induced spreading. Additionally, we identified a novel role for Ezrin downstream of Rap1. Ezrin was necessary for Rap-induced cell spreading, but not Rap-induced cell adhesion or basal adhesion processes. Furthermore, Ezrin depletion inhibited Rap-induced cell spreading in several cell lines, including primary human umbilical vein endothelial cells. Interestingly, Radixin and Moesin, two proteins with high homology to Ezrin, are not required for Rap-induced cell spreading and cannot compensate for loss of Ezrin to rescue Rap-induced cell spreading. Here, we present a novel function for Ezrin in Rap1-induced cell spreading and evidence of a non-redundant role of an ERM family member.
authors.affiliation: Molecular Cancer Research, Centre for Biomedical Genetics and Cancer Genomics Centre, University Medical Centre Utrecht, 3584 CG Utrecht, The Netherlands. S.Ross@umcutrecht.nl
authors.forename: Sarah H
authors.initials: SH
authors.lastname: Ross
authors.forename: Anneke
authors.initials: A
authors.lastname: Post
authors.forename: Judith H
authors.initials: JH
authors.lastname: Raaijmakers
authors.forename: Ingrid
authors.initials: I
authors.lastname: Verlaan
authors.forename: Martijn
authors.initials: M
authors.lastname: Gloerich
authors.forename: Johannes L
authors.initials: JL
authors.lastname: Bos
mesh_terms: D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D002448:Cell Adhesion / Q000187:drug effects*; D048430:Cell Shape / Q000187:drug effects; D000242:Cyclic AMP / Q000031:analogs & derivatives / Q000494:pharmacology; D003598:Cytoskeletal Proteins / Q000235:genetics / Q000378:metabolism*; D022001:Focal Adhesions / Q000378:metabolism; D020662:Guanine Nucleotide Exchange Factors / Q000819:agonists / Q000378:metabolism; D006801:Humans; D008840:Microfilament Proteins / Q000235:genetics / Q000378:metabolism; D034622:RNA Interference; D015398:Signal Transduction; D016608:Talin / Q000235:genetics / Q000378:metabolism; D020827:rap1 GTP-Binding Proteins / Q000819:agonists / Q000378:metabolism*; D000099149:Ezrin
chemical_list: D002352:Carrier Proteins; D000242:Cyclic AMP; D003598:Cytoskeletal Proteins; D020662:Guanine Nucleotide Exchange Factors; D008840:Microfilament Proteins; D016608:Talin; D020827:rap1 GTP-Binding Proteins; D000099149:Ezrin; C473217:8-(4-chloro-phenylthio)-2'-O-methyladenosine-3'-5'-cyclic monophosphate; C548041:RADIL protein, human; C116122:RAPGEF3 protein, human; C071058:moesin