Expression of the primary angle closure glaucoma (PACG) susceptibility gene PLEKHA7 in endothelial and epithelial cell junctions in the eye.

Abstract

The role of the recently identified primary angle closure glaucoma (PACG) susceptibility gene, pleckstrin homology domain containing, family A member 7 (PLEKHA7), in PACG is unknown. PLEKHA7 associates with apical junctional complexes (AJCs) and is thus implicated in paracellular fluid regulation. We aimed to determine PLEKHA7's localization in the eye and its association with AJCs to elucidate its potential role in PACG. Total RNA from ocular tissues was isolated and analyzed by real-time PCR. Frozen and paraffin-embedded human globes were sectioned and used for immunohistochemistry and immunofluorescence analysis. Specific PLEKHA7 expression was found in the muscles, vascular endothelium, and epithelium of the iris, ciliary body and ciliary processes, trabecular meshwork (TM), and choroid. PLEKHA7 expression in musculature and vascular endothelium was confirmed with smooth muscle marker, SMA, and endothelium marker, PECAM-1, respectively. At the above sites, PLEKHA7 colocalization was seen with adherens junction markers (E-cadherin and β-catenin) and tight junction markers (ZO-1). Specific localization of PLEKHA7 was found within PACG-related structures (iris, ciliary body, and choroid) and blood-aqueous barrier (BAB) structures (posterior iris epithelium, nonpigmented ciliary epithelium, iris and ciliary body microvasculature). The association of PLEKHA7 with AJCs in the eye suggests a potential role for PLEKHA7 in PACG via fluidic regulation. Novel expression of PLEKHA7 was also seen in the ocular smooth muscles and vascular endothelia.