title: Activation of Rap1 inhibits NADPH oxidase-dependent ROS generation in retinal pigment epithelium and reduces choroidal neovascularization.
abstract: Activation of Rap1 GTPase can improve the integrity of the barrier of the retina pigment epithelium (RPE) and reduce choroidal neovascularization (CNV). Inhibition of NADPH oxidase activation also reduces CNV. We hypothesize that Rap1 inhibits NADPH oxidase-generated ROS and thereby reduces CNV formation. Using a murine model of laser-induced CNV, we determined that reduced Rap1 activity in RPE/choroid occurred with CNV formation and that activation of Rap1 by 2'-O-Me-cAMP (8CPT)-reduced laser-induced CNV via inhibiting NADPH oxidase-generated ROS. In RPE, inhibition of Rap1 by Rap1 GTPase-activating protein (Rap1GAP) increased ROS generation, whereas activation of Rap1 by 8CPT reduced ROS by interfering with the assembly of NADPH oxidase membrane subunit p22phox with NOX4 or cytoplasmic subunit p47phox. Activation of NADPH oxidase with Rap1GAP reduced RPE barrier integrity via cadherin phosphorylation and facilitated choroidal EC migration across the RPE monolayer. Rap1GAP-induced ROS generation was inhibited by active Rap1a, but not Rap1b, and activation of Rap1a by 8CPT in Rap1b(-/-) mice reduced laser-induced CNV, in correlation with decreased ROS generation in RPE/choroid. These findings provide evidence that active Rap1 reduces CNV by interfering with the assembly of NADPH oxidase subunits and increasing the integrity of the RPE barrier.
authors.affiliation: 1John A. Moran Eye Center, University of Utah, 65 N. Mario Capecchi Dr., Salt Lake City, UT 84132. me.hartnett@hsc.utah.edu.
authors.forename: Haibo
authors.initials: H
authors.lastname: Wang
authors.forename: Yanchao
authors.initials: Y
authors.lastname: Jiang
authors.forename: Dallas
authors.initials: D
authors.lastname: Shi
authors.forename: Lawrence A
authors.initials: LA
authors.lastname: Quilliam
authors.forename: Magdalena
authors.initials: M
authors.lastname: Chrzanowska-Wodnicka
authors.forename: Erika S
authors.initials: ES
authors.lastname: Wittchen
authors.forename: Dean Y
authors.initials: DY
authors.lastname: Li
authors.forename: M Elizabeth
authors.initials: ME
authors.lastname: Hartnett
mesh_terms: D000818:Animals; D020256:Choroidal Neovascularization / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D019255:NADPH Oxidases / Q000378:metabolism*; D010084:Oxidation-Reduction; D017382:Reactive Oxygen Species / Q000378:metabolism*; D055213:Retinal Pigment Epithelium / Q000378:metabolism*; D020827:rap1 GTP-Binding Proteins / Q000378:metabolism*
chemical_list: D017382:Reactive Oxygen Species; D019255:NADPH Oxidases; C060505:neutrophil cytosolic factor 1; D020827:rap1 GTP-Binding Proteins
keywords: GTPase-activating proteins; NOX4; barrier integrity; p22phox; p47phox
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