Targeting the tight junction protein, zonula occludens-1, with the connexin43 mimetic peptide, ?CT1, reduces VEGF-dependent RPE pathophysiology.

ABSTRACT: A critical target tissue in age-related macular degeneration (AMD) is the retinal pigment epithelium (RPE), which forms the outer blood-retina barrier (BRB). RPE-barrier dysfunction might result from attenuation/disruption of intercellular tight junctions. Zonula occludens-1 (ZO-1) is a major structural protein of intercellular junctions. A connexin43-based peptide mimetic, ?CT1, was developed to competitively block interactions at the PDZ2 domain of ZO-1, thereby inhibiting ligands that selectively bind to this domain. We hypothesized that targeting ZO-1 signaling using ?CT1 would maintain BRB integrity and reduce RPE pathophysiology by stabilizing gap- and/or tight-junctions. RPE-cell barrier dysfunction was generated in mice using laser photocoagulation triggering choroidal neovascularization (CNV) or bright light exposure leading to morphological damage. ?CT1 was delivered via eye drops. ?CT1 treatment reduced CNV development and fluid leakage as determined by optical coherence tomography, and damage was correlated with disruption in cellular integrity of surrounding RPE cells. Light damage significantly disrupted RPE cell morphology as determined by ZO-1 and occludin staining and tiling pattern analysis, which was prevented by ?CT1 pre-treatment. In vitro experiments using RPE and MDCK monolayers indicated that ?CT1 stabilizes tight junctions, independent of its effects on Cx43. Taken together, stabilization of intercellular junctions by ?CT1 was effective in ameliorating RPE dysfunction in models of AMD-like pathology.Key message: The connexin43 mimetic ?CT1 accumulates in the mouse retinal pigment epithelium following topical delivery via eye drops. ?CT1 eye drops prevented RPE-cell barrier dysfunction in two mouse models. ?CT1 stabilizes intercellular tight junctions. Stabilization of cellular junctions via ?CT1 may serve as a novel therapeutic approach for both wet and dry age-related macular degeneration.

SUBMITTER: Obert E 

PROVIDER: S-EPMC5710814 | biostudies-literature | 2017 May

REPOSITORIES: biostudies-literature