title: Stable interaction between alpha5beta1 integrin and Tie2 tyrosine kinase receptor regulates endothelial cell response to Ang-1.
abstract: During angiogenic remodeling, Ang-1, the ligand of Tie2 tyrosine kinase, is involved in vessel sprouting and stabilization through unclear effects on nascent capillaries and mural cells. In our study, we hypothesized that the Ang-1/Tie2 system could cross-talk with integrins, and be influenced by the dynamic interactions between extracellular matrix and endothelial cells (ECs). Here, we show that alpha5beta1 specifically sensitizes and modulates Tie2 receptor activation and signaling, allowing EC survival at low concentrations of Ang-1 and inducing persistent EC motility. Tie2 and alpha5beta1 interact constitutively; alpha5beta1 binding to fibronectin increases this association, whereas Ang-1 stimulation recruits p85 and FAK to this complex. Furthermore, we demonstrate that Ang-1 is able to mediate selectively alpha5beta1 outside-in FAK phosphorylation. Thus, Ang-1 triggers signaling pathways through Tie2 and alpha5beta1 receptors that could cross-talk when Tie2/alpha5beta1 interaction occurs in ECs plated on fibronectin. By using blocking antibodies, we consistently found that alpha5beta1, but not alphavbeta3 activation, is essential to Ang-1-dependent angiogenesis in vivo.
authors.affiliation: Department of Oncological Sciences and Institute for Cancer Research and Treatment, University of Turin, 10060 Candiolo, Italy. ilaria.cascone@curie.fr
authors.forename: Ilaria
authors.initials: I
authors.lastname: Cascone
authors.forename: Lucia
authors.initials: L
authors.lastname: Napione
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Maniero
authors.forename: Guido
authors.initials: G
authors.lastname: Serini
authors.forename: Federico
authors.initials: F
authors.lastname: Bussolino
mesh_terms: D042683:Angiopoietin-1 / Q000494:pharmacology*; D000818:Animals; D016466:CHO Cells; D002448:Cell Adhesion / Q000187:drug effects; D018929:Cell Culture Techniques; D002460:Cell Line; D002465:Cell Movement / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002642:Chick Embryo; D049033:Chorioallantoic Membrane / Q000098:blood supply; D002867:Chromones / Q000494:pharmacology; D024042:Collagen Type I / Q000378:metabolism; D006224:Cricetinae; D003412:Cricetulus; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D005340:Fibrinogen / Q000378:metabolism; D005353:Fibronectins / Q000378:metabolism; D006801:Humans; D039081:Integrin alpha5beta1 / Q000378:metabolism*; D007700:Kinetics; D009025:Morpholines / Q000494:pharmacology; D018919:Neovascularization, Physiologic / Q000187:drug effects; D011233:Precipitin Tests; D042787:Receptor, TIE-2 / Q000378:metabolism*; D014471:Umbilical Veins / Q000166:cytology
chemical_list: D042683:Angiopoietin-1; D002867:Chromones; D024042:Collagen Type I; D005353:Fibronectins; D039081:Integrin alpha5beta1; D009025:Morpholines; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; D005340:Fibrinogen; D042787:Receptor, TIE-2