title: EphrinA1 inhibits vascular endothelial growth factor-induced intracellular signaling and suppresses retinal neovascularization and blood-retinal barrier breakdown.
abstract: The Eph receptor/ephrin system is a recently discovered regulator of vascular development during embryogenesis. Activation of EphA2, one of the Eph receptors, reportedly suppresses cell proliferation and adhesion in a wide range of cell types, including vascular endothelial cells. Vascular endothelial growth factor (VEGF) plays a primary role in both pathological angiogenesis and abnormal vascular leakage in diabetic retinopathy. In the study described herein, we demonstrated that EphA2 stimulation by ephrinA1 in cultured bovine retinal endothelial cells inhibits VEGF-induced VEGFR2 receptor phosphorylation and its downstream signaling cascades, including PKC (protein kinase C)-ERK (extracellular signal-regulated kinase) 1/2 and Akt. This inhibition resulted in the reduction of VEGF-induced angiogenic cell activity, including migration, tube formation, and cellular proliferation. These inhibitory effects were further confirmed in animal models. Intraocular injection of ephrinA1 suppressed ischemic retinal neovascularization in a dose-dependent manner in a mouse model. At a dose of 125 ng/eye, the inhibition was 36.0 +/- 14.9% (P < 0.001). EphrinA1 also inhibited VEGF-induced retinal vascular permeability in a rat model by 46.0 +/- 10.0% (P < 0.05). These findings suggest a novel therapeutic potential for EphA2/ephrinA1 in the treatment of neovascularization and vasopermeability abnormalities in diabetic retinopathy.
authors.affiliation: Department of Ophthalmology and Visual Sciences, Kyoto University Graduate School of Medicine, 54 Kawara-cho Shogoin, Sakyo-Ku, Kyoto City 606-8507, Japan.
authors.forename: Tomonari
authors.initials: T
authors.lastname: Ojima
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Takagi
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Suzuma
authors.forename: Hideyasu
authors.initials: H
authors.lastname: Oh
authors.forename: Izumi
authors.initials: I
authors.lastname: Suzuma
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Ohashi
authors.forename: Daisuke
authors.initials: D
authors.lastname: Watanabe
authors.forename: Eri
authors.initials: E
authors.lastname: Suganami
authors.forename: Tomoaki
authors.initials: T
authors.lastname: Murakami
authors.forename: Masafumi
authors.initials: M
authors.lastname: Kurimoto
authors.forename: Yoshihito
authors.initials: Y
authors.lastname: Honda
authors.forename: Nagahisa
authors.initials: N
authors.lastname: Yoshimura
mesh_terms: D000818:Animals; D001813:Blood-Retinal Barrier / Q000378:metabolism* / Q000473:pathology; D015152:Blotting, Northern; D015153:Blotting, Western; D002417:Cattle; D002465:Cell Movement / Q000502:physiology; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000378:metabolism; D036382:Ephrin-A1 / Q000378:metabolism*; D036383:Ephrin-A2 / Q000378:metabolism; D007150:Immunohistochemistry; D047468:Immunoprecipitation; D020287:In Situ Nick-End Labeling; D051379:Mice; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D051058:Oncogene Protein v-akt / Q000378:metabolism; D010539:Permeability; D011493:Protein Kinase C / Q000378:metabolism; D051381:Rats; D015861:Retinal Neovascularization / Q000378:metabolism*; D012171:Retinal Vessels / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism*; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000378:metabolism
chemical_list: D036382:Ephrin-A1; D036383:Ephrin-A2; D042461:Vascular Endothelial Growth Factor A; D040301:Vascular Endothelial Growth Factor Receptor-2; D051058:Oncogene Protein v-akt; D011493:Protein Kinase C; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3