title: Platelet-endothelial cell adhesion molecule-1 modulates endothelial migration through its immunoreceptor tyrosine-based inhibitory motif.
abstract: Coordinated migration of endothelial cells models the remodeling of existing endothelia as well as angiogenesis and vasculogenesis. Platelet-endothelial cell adhesion molecule-1, PECAM-1, a transmembrane endothelial adhesion protein, binds and activates the tyrosine phosphatase SHP-2 via phosphotyrosines 663 and 686. PECAM-1 phosphorylation and recruitment of SHP-2 are regulated by cell-cell and cell-substrate adhesion. We found that PECAM-1 is dephosphorylated on tyrosine 686 during endothelial migration, resulting in diffuse dispersal of PECAM-1 and SHP-2. Overexpression of native PECAM-1 slowed, and nonphosphorylatable PECAM-1 increased, endothelial migration, implying that the SHP-2-regulatory phosphotyrosines negatively regulate migration. Using differentially phosphorylated recombinant proteins we found that phosphotyrosine 686 preferentially mediates binding and 663 mediates activation of SHP-2 by PECAM-1. In PECAM-1-null endothelial cells, SHP-2 bound and dephosphorylated an alternative set of phosphoproteins and its distribution to the cytoskeletal fraction was significantly decreased. Tyrosine phosphorylation of beta-catenin and focal adhesion kinase was increased in endothelial cells overexpressing nonphosphorylatable PECAM-1. Thus homophilically engaged, tyrosine-phosphorylated PECAM-1 locally activates SHP-2 at cell-cell junctions; with disruption of the endothelial monolayer, selective dephosphorylation of PECAM-1 leads to redistribution of SHP-2 and pro-migratory changes in phosphorylation of cytoskeletal and focal contact components.
authors.affiliation: Department of Pathology, Yale University School of Medicine, Lauder Hall 115, 310 Cedar St., New Haven, CT 06511, USA.
authors.forename: Dita
authors.initials: D
authors.lastname: Gratzinger
authors.forename: Mark
authors.initials: M
authors.lastname: Barreuther
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Madri
mesh_terms: D022005:Adherens Junctions / Q000378:metabolism; D020816:Amino Acid Motifs; D000818:Animals; D002417:Cattle; D002465:Cell Movement / Q000502:physiology*; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism*; D004789:Enzyme Activation; D047908:Intracellular Signaling Peptides and Proteins; D051379:Mice; D018345:Mice, Knockout; D010766:Phosphorylation; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D017027:Protein Tyrosine Phosphatases / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D014443:Tyrosine / Q000378:metabolism*
chemical_list: D047908:Intracellular Signaling Peptides and Proteins; D019408:Platelet Endothelial Cell Adhesion Molecule-1; D011993:Recombinant Fusion Proteins; D014443:Tyrosine; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D017027:Protein Tyrosine Phosphatases; C516725:Ptpn11 protein, mouse