title: Phosphorylation of ephrin-B1 via the interaction with claudin following cell-cell contact formation.
abstract: The interaction of the Eph family of receptor protein tyrosine kinase and its ligand ephrin family induces bidirectional signaling via the cell-cell contacts. Although most previous studies have focused on the function of Eph-ephrin pathways in the neural system and endothelial cells, this process also occurs in epithelial and cancer cells, of which the biological involvement is poorly understood. We show that ephrin-B1 creates an in vivo complex with adjacent claudin1 or claudin4 via the extracellular domains of these proteins. The cytoplasmic domain of ephrin-B1 was phosphorylated on tyrosine residues upon the formation of cell-cell contacts, possibly recognizing an intercellular adhesion of claudins. Phosphorylation of ephrin-B1 induced by claudins was abolished by the treatment with 4-amino-5-(4-chlorophenyl)-7-(t-butyl)pyrazolo[3,4-d]pyrimidine, an inhibitor of the Src family kinases. Moreover, overexpression of ephrin-B1 triggered consequent change in the level of cell-cell adhesion depending on its phosphorylation. These results suggest that ephrin-B1 mediated the cell-cell adhesion of epithelial and cancer cells via a novel Eph receptor-independent mechanism.
authors.affiliation: Growth Factor Division, National Cancer Center Research Institute, Tsukiji, Chuo-ku, Tokyo, Japan.
authors.forename: Masamitsu
authors.initials: M
authors.lastname: Tanaka
authors.forename: Reiko
authors.initials: R
authors.lastname: Kamata
authors.forename: Ryuichi
authors.initials: R
authors.lastname: Sakai
mesh_terms: D000818:Animals; D019556:COS Cells; D002448:Cell Adhesion / Q000502:physiology*; D002460:Cell Line; D002522:Chlorocebus aethiops; D062445:Claudin-1; D062506:Claudin-4; D004285:Dogs; D004791:Enzyme Inhibitors / Q000494:pharmacology; D036387:Ephrin-B1 / Q000737:chemistry / Q000378:metabolism*; D004847:Epithelial Cells / Q000502:physiology; D008565:Membrane Proteins / Q000378:metabolism*; D010766:Phosphorylation; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011743:Pyrimidines / Q000494:pharmacology; D019108:Tight Junctions / Q000502:physiology
chemical_list: C412373:AG 1879; D062445:Claudin-1; D062506:Claudin-4; D004791:Enzyme Inhibitors; D036387:Ephrin-B1; D008565:Membrane Proteins; D011743:Pyrimidines