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Cheng-mao Lin, Andreia Goncalves, Jason M Keil, Sarah Sheskey, David A Antonetti; Endothelial expression of permeability-resistant occludin mutant preserves visual function in diabetes. Invest. Ophthalmol. Vis. Sci. 2019;60(9):2692.
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© ARVO (1962-2015); The Authors (2016-present)
Previous data from our laboratory has shown that VEGF-induced occludin phosphorylation at S490 leads to its ubiquitination and endocytosis of the junctional complex. The present work aims to elucidate the contribution of this phospho-site in blood-retina barrier (BRB) permeability and visual function.
We generated conditional expressing floxed stop mice with transgenic Wt human occludin (WtOCC+/+) or the nonphosphorylatable alanine mutant of occludin Ser490 (S490AOCC+/+) and induced endothelial expression with either Tie2Cre or PDGFiCre. Transgenic mice were also crossed with floxed endogenous occludin (Occfl/fl) mice. VEGF (200 ng/eye) was injected intravitreally and vascular permeability to Texas red-70 kDa Dextran and FITC-BSA was assessed. Spectral domain optical coherence tomography (OCT) was used to determine retinal layer thickness in vivo. Diabetes was induced by streptozotocin injection in Tie2-Cre mice and visual acuity and contrast sensitivity were determined by the optokinetic response.
Mice expressing S490AOCC+/+ under the Tie2-Cre promoter were protected against the increase in vascular permeability induced by VEGF when compared to Tie2-Cre control mice. Conditional deletion of endogenous occludin and expression of S490AOCC+/+ demonstrated protection against VEGF-induced permeability when compared to expression of WtOCC+/+, with reductions in both VEGF-induced permeability as measured by solute flux and fluid accumulation as determined by OCT measures of retinal thickness. Conditional expression of the S490AOCC+/+ mutant did not affect retinal thinning induced by diabetes, however, expression of the permeability resistant mutant of occludin completely blocked the reduction in visual acuity and contrast sensitivity induced by diabetes at 4 months.
Taken together, these data demonstrate the role of occludin phosphorylation in vivo on VEGF-induced permeability and reveals that transgenic targeting of retinal vascular permeability preserves visual function in diabetes.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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