Abstract
Abstract: :
Purpose: To identify development-associated retinal genes whose expression profile is conserved under normal and pathological conditions. Methods: Mice were subjected to hyperoxia from post natal day 7 (p7) to p12, or reared in normoxic conditions. Retinas were collected from mice at p12, immediately after removal from hyperoxia, after 6 hours in room air, and at p18. RNA was prepared from pools of 6 retinas from duplicate groups of animals at each time point. The RNA was reverse-transcribed, cRNA was prepared from cDNA, labeled and hybridized to mouse Affymetrix microarray chips. Microarray results were collected by laser scanning, and analyzed using a non-parametric method. Results were compared against nucleotide and protein databases. Genes were sorted according to their possible developmental significance. Results: The Affymetrix mouse chip U74Av2 contains approximately 6,000 full-length mouse genes and 6,000 expressed sequence tag (EST) clusters from the UniGene database. Fifty two of the genes and ESTs were overexpressed in p12 retinas as compared to the p18 retinas (p<0.000125). Among the differentially expressed genes were transcription and cell cycle regulators, differentiation factors and neuronal specific genes. Fifty six known genes and ESTs were overexpressed in the p18 retinas (p<0.000125), including extracellular matrix proteins and angiogenesis inhibitors. Conclusions: We identified 108 genes that showed significant changes in expression from p12 to p18. These changes were not related to rearing conditions, and occurred in both normal and hyperoxia-exposed groups. The nonparametric (model-free) method for the comparison of gene expression levels under different conditions avoids arbitrary assumptions about the nature of gene expression changes and fluctuations. Some of the differentially expressed genes were previously reported to have a role in promoting or inhibiting growth and development. Other genes and ESTs may have novel development-associated functions. The different gene expression profiles of p12 and p18 retinas imply an ongoing process of retinal development during this period. Gene expression profiling of retinas at different ages provides insight into the natural history of retinal development.
Keywords: gene microarray • retinal development