The neural retina maintains integrins in the apical membrane of the RPE early in development. Invest

Purpose. The retinal pigment epithelium (RPE) lines the interface between the neural retina and the choroid. Early in chicken development, the j81 family of integrins resides in the apical (facing the neural retina) and basolateral (facing the choroid) membranes of RPE. Later in development, integrins reside only in the basolateral membranes, which is more typical of simple transporting epithelia. The authors examined whether the distribution of integrins is regulated by the neural retina. Methods. Individual integrins were examined by studying the individual a-subunits that form heterodimers with the /31 subunit. The expression and distribution of these subunits were determined by immunoblotting and immunocytochemistry. Results. Subunits aS and a6 exemplified contrasting behaviors. Early and late in development, a3 was found only in the basal membranes. As was j81, the distribution of a6 was nonpolarized early in development but was basal later in development. The effect of the immature neural retina was determined by reconstituting the RPE:neural retinal interface in explant culture. Absent the neural retina, a6 and /31 were removed from the apical membrane. When present, the immature neural retina maintained both subunits in the apical membrane. The neural retina was effective only if the outer (primordial photoreceptor) surface of the retina apposed the RPE. Conclusions. These data suggest that matrix or intercellular interactions determine the distribution of individual integrins. Further, the changes in integrin distribution during development reflect the maturation of the primordial interphotoreceptor matrix or photoreceptor cell layer. Invest Ophthalmol Vis Sci. 1994; 35:2567-2576 1 he retinal pigment epithelium (RPE) is a simple transporting epithelium that forms the outer bloodretinal barrier and helps regulate retinal physiology. 1 The RPE lies at the interface between the neural retina and the choroid. As would be expected from its extensive interactions with these tissues, the development of the RPE is closely coordinated with the neural retina and the choroid. For example, changes in gene expression, or the distribution of the Na,K-ATPase, parallel developmental changes in the neural retina

Minimal Effects of VEGF and Anti-VEGF Drugs on the Permeability or Selectivity of RPE Tight Junctions

To date, this study is the most complete characterization of the composition, selectivity, and permeability of human RPE tight junctions and how they may be affected by VEGF and drugs commonly used to treat age-related macular degeneration

Claudin-19 and the Barrier Properties of the Human Retinal Pigment Epithelium

Claudin-19 is essential for RPE tight junctions, but minor claudins may create regional variations in barrier properties. Subretinal serum “tightens” the junctions, which might be a defense mechanism that would retard the spread of edema due to AMD