Preferential Integrin Gene Expression by Human Retinal Pigment Epithelium (RPE) at Submacular Region

Abstract

Abstract: : Purpose: To reveal differentially expressed integrin genes in central versus peripheral human RPE. Methods: 4 eye-bank eyes from 2 individuals without known ocular diseases were included in this study. Central (5.5 mm in diameter) and peripheral (8 mm in diameter) RPE were isolated from each eye. Total RNA was extracted and was reverse transcribed into sscDNA and subsequently amplified by PCR using primers designed with anchored sequence. The products of cDNA were labeled with [³²P]dCTP for generation of probes. Hybridization to human integrin gene arrays was performed according to the manufacture’s manual (Superarray). The hybridization signals were globally normalized and filtered, and then data were analyzed by GEArray software. Results: ~2.5 x 10⁵ RPE cells were harvested from individual retinal regions to yield ~1.1 to 1.6 µg for total RNA. Of the 23 integrin cDNA elements on the array, 15 integrins produced similar results in replicate experiments. Four integrin genes were identified to differ in comparison of RPE from the central to the peripheral region. α5 and ß1 intergin gene expression levels were ~3-fold higher in the central RPE than the peripheral RPE. α6 and ß3 gene expression levels were 2-fold lower in the central RPE than that in periphery. Conclusions: Differentially expressed integrin genes of the central RPE indicate specific integrins of RPE cells at submacular region plays a preferential role in interaction with their extracellular matrix. In almost all vertebrae cells, α5ß1 is a fibronectin receptor. The upregulation of integrin α5 and ß1 may preferentially modulate fibronectin in both interreceptor matrix and Bruch’s membrane. Such ECM remodeling process at macular region may represent a new mechanism for understanding of central retinal diseases (e.g., age-related macular degeneration).

Keywords: age-related macular degeneration • retinal pigment epithelium • gene/expression