title: Loss of SPARC-mediated VEGFR-1 suppression after injury reveals a novel antiangiogenic activity of VEGF-A.
abstract: VEGF-A promotes angiogenesis in many tissues. Here we report that choroidal neovascularization (CNV) incited by injury was increased by excess VEGF-A before injury but was suppressed by VEGF-A after injury. This unorthodox antiangiogenic effect was mediated via VEGFR-1 activation and VEGFR-2 deactivation, the latter via Src homology domain 2-containing (SH2-containing) tyrosine phosphatase-1 (SHP-1). The VEGFR-1-specific ligand placental growth factor-1 (PlGF-1), but not VEGF-E, which selectively binds VEGFR-2, mimicked these responses. Excess VEGF-A increased CNV before injury because VEGFR-1 activation was silenced by secreted protein, acidic and rich in cysteine (SPARC). The transient decline of SPARC after injury revealed a temporal window in which VEGF-A signaling was routed principally through VEGFR-1. These observations indicate that therapeutic design of VEGF-A inhibition should include consideration of the level and activity of SPARC.
authors.affiliation: Department of Ophthalmology and Visual Sciences, University of Kentucky, Lexington, Kentucky 40536-0284, USA.
authors.forename: Miho
authors.initials: M
authors.lastname: Nozaki
authors.forename: Eiji
authors.initials: E
authors.lastname: Sakurai
authors.forename: Brian J
authors.initials: BJ
authors.lastname: Raisler
authors.forename: Judit Z
authors.initials: JZ
authors.lastname: Baffi
authors.forename: Jassir
authors.initials: J
authors.lastname: Witta
authors.forename: Yuichiro
authors.initials: Y
authors.lastname: Ogura
authors.forename: Rolf A
authors.initials: RA
authors.lastname: Brekken
authors.forename: E Helene
authors.initials: EH
authors.lastname: Sage
authors.forename: Balamurali K
authors.initials: BK
authors.lastname: Ambati
authors.forename: Jayakrishna
authors.initials: J
authors.lastname: Ambati
mesh_terms: D020533:Angiogenesis Inhibitors / Q000378:metabolism*; D000818:Animals; D020256:Choroidal Neovascularization; D005123:Eye / Q000033:anatomy & histology / Q000378:metabolism / Q000473:pathology; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D015676:Osteonectin / Q000235:genetics / Q000378:metabolism*; D000072483:Placenta Growth Factor; D011257:Pregnancy Proteins / Q000378:metabolism; D054645:Protein Phosphatase 1; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D017027:Protein Tyrosine Phosphatases / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism*; D040281:Vascular Endothelial Growth Factor Receptor-1 / Q000235:genetics / Q000378:metabolism*; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000235:genetics / Q000378:metabolism
chemical_list: D020533:Angiogenesis Inhibitors; D047908:Intracellular Signaling Peptides and Proteins; D015676:Osteonectin; C000608036:PGF protein, human; C000608037:Pgf protein, mouse; D011257:Pregnancy Proteins; D042461:Vascular Endothelial Growth Factor A; C467480:vascular endothelial growth factor A, mouse; D000072483:Placenta Growth Factor; D040281:Vascular Endothelial Growth Factor Receptor-1; D040301:Vascular Endothelial Growth Factor Receptor-2; D054645:Protein Phosphatase 1; C509249:PTPN6 protein, human; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D017027:Protein Tyrosine Phosphatases; C509248:Ptpn6 protein, mouse