title: Effects of protein and gene transfer of the angiopoietin-1 fibrinogen-like receptor-binding domain on endothelial and vessel organization.
abstract: The vessel-stabilizing effect of angiopoietin-1 (Ang1)/Tie2 receptor signaling is a potential target for pro-angiogenic therapies as well as anti-angiogenic inhibition of tumor growth. We explored the endothelial and vascular specific activities of the Ang1 monomer, i.e. dissociated from its state as an oligomer. A truncated monomeric Ang1 variant (i.e. DeltaAng1) containing the isolated fibrinogen-like receptor-binding domain of Ang1 was created and recombinantly produced in insect cells. DeltaAng1 ligated the Tie2 receptor without triggering its phosphorylation. Moreover, monomeric DeltaAng1 was observed to bind alpha(5)beta(1) integrin with similar affinity compared with Tie2. Unexpectedly, in vitro treatment of endothelial cells with DeltaAng1 showed some of the known effects of full-length Ang1, including inhibition of basal endothelial cell permeability and stimulation of cell adhesion as well as activation of MAPKs. Local treatment of the microvasculature of the developing chicken chorioallantoic membrane with the DeltaAng1 protein led to profound reduction of the mean vascular length density, thinning of vessels, and reduction of the number of vessel branching points. Similar effects were observed in side-by-side experiments with the recombinant full-length Ang1 protein. These effects of simplification of the vessel branching pattern were confirmed through local gene transfer with lentiviral particles encoding DeltaAng1 or full-length Ang1. Together, our findings suggest a potential use for exogenous Ang1 in reducing rather than increasing vascular density. Furthermore, we show that the isolated receptor-binding domain of Ang1 is capable of mediating some effects of full-length Ang1 independently of Tie2 phosphorylation, possibly through integrin ligation.
authors.affiliation: Department of Materials Science, and Institute of Biomedical Engineering, Swiss Federal Institute of Technology-Zurich and University of Zurich, Zurich 8044, Switzerland.
authors.forename: Cornelia C
authors.initials: CC
authors.lastname: Weber
authors.forename: Hao
authors.initials: H
authors.lastname: Cai
authors.forename: Martin
authors.initials: M
authors.lastname: Ehrbar
authors.forename: Hisashi
authors.initials: H
authors.lastname: Kubota
authors.forename: Georg
authors.initials: G
authors.lastname: Martiny-Baron
authors.forename: Wilfried
authors.initials: W
authors.lastname: Weber
authors.forename: Valentin
authors.initials: V
authors.lastname: Djonov
authors.forename: Ernst
authors.initials: E
authors.lastname: Weber
authors.forename: Ajit S
authors.initials: AS
authors.lastname: Mallik
authors.forename: Martin
authors.initials: M
authors.lastname: Fussenegger
authors.forename: Karl
authors.initials: K
authors.lastname: Frei
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Hubbell
authors.forename: Andreas H
authors.initials: AH
authors.lastname: Zisch
mesh_terms: D042683:Angiopoietin-1 / Q000235:genetics* / Q000502:physiology*; D000818:Animals; D001011:Aorta / Q000166:cytology / Q000378:metabolism; D016367:Baculoviridae / Q000378:metabolism; D019921:Biotinylation; D002448:Cell Adhesion; D002460:Cell Line; D002478:Cells, Cultured; D002642:Chick Embryo; D004305:Dose-Response Relationship, Drug; D004591:Electrophoresis, Polyacrylamide Gel; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism*; D004789:Enzyme Activation; D005337:Fibrin / Q000737:chemistry; D005340:Fibrinogen / Q000737:chemistry; D018014:Gene Transfer Techniques; D005822:Genetic Vectors; D006801:Humans; D007313:Insecta; D016023:Integrins / Q000378:metabolism; D016086:Lentivirus / Q000235:genetics; D020935:MAP Kinase Signaling System; D008954:Models, Biological; D009130:Muscle, Smooth / Q000166:cytology; D009389:Neovascularization, Pathologic; D010539:Permeability; D010766:Phosphorylation; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D042787:Receptor, TIE-2 / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry; D012685:Sepharose / Q000737:chemistry; D015398:Signal Transduction
chemical_list: D042683:Angiopoietin-1; D016023:Integrins; D011994:Recombinant Proteins; D005337:Fibrin; D005340:Fibrinogen; D012685:Sepharose; D042787:Receptor, TIE-2