Micro-Array Analysis of Gene Expression in Light-Induced Retinal Degeneration Susceptibility

Abstract

Abstract: : Purpose: Rats taken at 0100 h and 1700 h have different levels of susceptibility to light-induced retinal degeneration (LIRD). Rats at 0100 h are susceptible to LIRD, while rats taken at 1700h are resistant to LIRD. We have previously shown that the gene expression profile in rat retina at 0100h is distinctly different from rat retina at 1700 h. We hypothesise that the inherent differences in the expressed retinal gene profile at different times of the day define a retinal environment that subsequently affects the physical response of the retina to intense light. In the current study we examine the expressed gene profile of the retina in 0100 h and 1700 h rats after exposure to 3 h of intense green light. Methods: Retinae were isolated from dark-reared rats that had been exposed to 3 h of intense green light commencing at 0100 h or 1700 h. Total RNA was isolated, and radiolabelled cDNA probes were generated and used to screen cDNA arrays (Atlas Array, Clontech Inc). Membranes were analyzed by visual inspection and with Atlas Image software to determine relative levels of gene expression. Northern analysis of selected clones was used to verify gene expression patterns. Results: In total 3,528 genes were examined by cDNA array analysis. Preliminary results indicate that 54 genes were differentially expressed, with 19 more highly expressed at 0100 h and 35 more highly expressed at 1700 h. Genes involved in vesicle endocytosis/exocytosis, and the immediate early gene jun, appear to be more highly expressed at 1700 h. Conclusions: We initially hypothesised that the inherent differences in the expressed retinal gene profile at different times of the day defined a retinal environment that affects the physical response of the retina to intense light. In the current study we demonstrate that the response of the 0100 h and the 1700 h rat retina to light exposure are different, as measured by changes in the expressed gene profile. Given the phenotypic outcomes of the light exposure at 0100 h VS 1700 h we are currently exploring the possibility that the genes that are inducible or repressible at 0100 h or 1700 h define a program of either retinal cell death susceptibility or resistance.

Keywords: gene microarray • retina • photoreceptors