Characterization of the Rat Rom1 Ortholog as Part of the Molecular Gene Profile of Light-induced Retinal Degeneration

Abstract

Abstract: : Purpose: The extent of light-induced retinal degeneration (LIRD) in rats varies with the duration of light exposure. The precise mechanism leading to the loss of visual cells in LIRD, although not fully understood, is believed to involve an oxidative stress mediated apoptotic pathway. We are interested in determining the molecular changes that occur in the transition from a normal to a damaged retina. To further elucidate the mechanism of retinal degeneration and to define the molecular environment in the retina after prolonged light exposure we screened a retinal cDNA library made from rats exposed to prolonged periods of light. Methods and Results: Retinal RNA from dark-reared albino rats as well as animals exposed to 8 h or 16 h of light was used to construct a cDNA library as well as cDNA probes. A differential cross-screening strategy was performed on an 8 h light-treated rat retinal cDNA library using cDNA probes derived from normal retinal RNA (dark reared rats) and 16 h light-exposed rat retinal RNA in order to identify differentially expressed genes. In total, after secondary and tertiary screens, 114 putative clones were isolated. DNA sequence data was obtained for 109 clones. Over half of these sequences correspond to either stress response (32) or cell metabolism (28) related genes. To confirm the success of the screen, Northern analysis was performed. One of the clones isolated corresponds to the rat ortholog of ROM1. Since this gene had not been characterized in the rat we choose it for further analysis. Conclusions: Functional classification of the genes isolated in our screen provides a "snapshot" of the gene expression profile occurring after prolonged light exposure. This provides information about the retina’s molecular environment. In addition our avenue of research also leads to the characterization of new genes. The characterization of the rat ROM1 gene adds to the growing list of mammalian ROM1 orthologs.

Keywords: gene/expression • retinal degenerations: cell biology • apoptosis/cell death