Abstract
Purpose: :
During aging neurons become more sensitive to stressors including oxidation, neurotrophin and oxygen deprivation, which represent conditions often associated with primary open angle glaucoma. In this work, we continued characterization of age-related changes by profiling genes expression in rat retinal ganglion cells (RGCs) of advanced age. We sought to establish correlation between such changes and reduction of stress tolerance by comparing 3 and 26 months old RGCs.
Methods: :
We compared gene expression profiles of acutely isolated young adult and aged RGCs using two-color oligo microarrays. Primary RGCs were isolated using two step immunopanning technique, RNA was subjected to two rounds of linear RNA amplification before probing Agilent Rat Genomic oligo arrays. After validation, normalization and statistical analysis the gene expression data was subjected to pathway analysis and interactome reconstructions in the MetaCore software.
Results: :
We have detected 344 genes with expression changes in excess of 1.5-fold, only 52 of which were up-regulated, while majority were down-regulated in 26 mo vs. 3 mo RGCs. The functional analysis revealed over-representation of several regulatory processes like Transmission of nerve impulse, Cell adhesion, Neurogenesis, as well as metabolic pathways, including Lyso-Phosphatidilserine, Lactosylceramide Glycosilceramide pathways among aging-activated genes, and N-acil-sphingosine-phosphate and ceramide pathways among downregulated genes. Network analysis revealed activation of small gene cluster regulated by TNF-α, Oct-1 ad c-Src; several large networks interlinked by c-Myc, androgen receptor, and Ubiquitine proteasome were retrieved from downregulated gene set. Inactivation of transcriptional machinery, degradation of misfolded proteins and selected metabolic processes were evident on the networks of aging neurons.
Conclusions: :
In this work we demonstrated feasibility of using acutely isolated retinal neurons for genome-wide gene expression profiling in studies of aging. The approach utilized for RNA purification in this study consistently produced RGC-specific gene expression profiles. Our comparison of the two age groups revealed statistically significant changes in several gene clusters, including those implicated in neurological disorders. The affected neuronal pathways identified in this study can potentially contribute to age-related increase in vulnerability to stress.
Keywords: aging • ganglion cells • gene/expression