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Updated: Mar 15, 2026
A Mouse Model for Laser-induced Choroidal Neovascularization
Published on: December 27, 2015
Retinal pigment epithelial cell expression of active Rap 1a by scAAV2 inhibits choroidal neovascularization
Haibo Wang1, Xiaokun Han2, Colin A Bretz1
1The John Moran Eye Center, University of Utah , Salt Lake City, Utah, USA.
Abstract:
To test the hypothesis that increased Rap1a activity specifically in retinal pigment epithelial cells resists choroidal neovascularization (CNV), self-complementary adeno-associated virus 2 (scAAV2) with RPE65-promoter-driven GFP vectors were generated and introduced subretinally into Rap1b-deficient mice. Six-week-old mice that received subretinal control (scAAV2-Con) or constitutively active Rap1a (scAAV2-CARap1a) showed strong GFP at the 5 × 10(8) viral particle/µl dose 5 weeks later without altering retinal morphology or function. Compared to scAAV2-Con- or phosphate-buffered saline (PBS)-injected, eyes injected with scAAV2-CARap1a had increased Rap1 in retinal pigment epithelial (RPE)/choroidal lysates and a significant reduction in CNV volume 7 days after laser, comparable to eyes that received intravitreal anti-VEGF versus IgG control. scAAV2-CARap1a-, but not anti-VEGF-, injected eyes had increased pan-cadherin in RPE/choroids. In cultured RPE cells, increased active Rap1a inhibited TNFα-induced disassociation of junctional pan-cadherin/β-catenin complexes, increased transepithelial electrical resistance through an interaction of β-catenin with phosphorylated scaffold protein, IQGAP1, and inhibited choroidal endothelial cell (CEC) transmigration of an RPE monolayer. This evidence shows that increased Rap1a activity specifically in RPE cells is sufficient to reduce CEC transmigration and CNV and involves IQGAP1-mediated protection of RPE junctional complexes.
Insights
Increased Rap1a activity in retinal pigment epithelial cells effectively reduces choroidal neovascularization (CNV). This occurs by protecting RPE cell junctions, offering a potential therapeutic strategy for CNV.
Area of Science:
- Ophthalmology
- Molecular Biology
- Cell Biology
Background:
- Choroidal neovascularization (CNV) is a major cause of vision loss.
- Retinal pigment epithelial (RPE) cells play a critical role in maintaining the blood-retinal barrier.
- Rap1a, a small GTPase, is implicated in cell adhesion and barrier function.
Purpose of the Study:
- To investigate if enhanced Rap1a activity in RPE cells can prevent CNV.
- To elucidate the molecular mechanisms by which Rap1a influences RPE cell integrity and CNV.
Main Methods:
- Generated self-complementary adeno-associated virus 2 (scAAV2) vectors expressing constitutively active Rap1a (CARap1a) under the RPE65 promoter.
- Subretinally injected vectors into Rap1b-deficient mice and induced CNV using laser photocoagulation.
- Analyzed RPE/choroidal lysates for Rap1 activity, junctional protein expression, and measured CNV volume.
- Assessed RPE cell barrier function and choroidal endothelial cell (CEC) transmigration in vitro.
Main Results:
- Subretinal injection of scAAV2-CARap1a increased Rap1 activity in RPE/choroidal lysates and significantly reduced CNV volume.
- CARap1a expression preserved RPE junctional complexes (pan-cadherin/β-catenin) and increased transepithelial electrical resistance.
- Active Rap1a inhibited TNFα-induced RPE barrier disruption and CEC transmigration.
- Increased Rap1a activity in RPE cells was comparable in efficacy to anti-VEGF treatment in reducing CNV.
Conclusions:
- Specific enhancement of Rap1a activity in RPE cells is sufficient to resist CNV development.
- Rap1a protects RPE barrier integrity by stabilizing junctional complexes, involving IQGAP1.
- Targeting Rap1a in RPE cells presents a novel therapeutic avenue for treating CNV.
