Abstract
Purpose::
Aging is a major risk factor for many progressive neurodegenerations. With age, neurons become more sensitive to changes in microenvironment, including oxidative stress, neurotrophin and oxygen deprivation, which are conditions often associated with primary open angle glaucoma (POAG). This increased susceptibility is likely to be reflected in neuronal genes expression profiles. In this work, we aimed to establish a correlation between age-related changes in expression profiles and reduction of stress tolerance in neurons by analyzing young and old ganglion cells (RGCs) isolated from rat retinas.
Methods::
We compared global gene expression profiles of old (15 mo) and young (3 mo) adult RGCs using two-color oligo microarrays. Primary RGCs were isolated using fluorescent-activated cell sorting (FACS) after being retrogradely labeled with 4DI-10ASP. Two rounds of linear RNA amplification provided RNA in quantities sufficient for probing Agilent Rat Genomic oligo arrays. Validation of genes with significantly changed expression levels was performed using quantitative RT-PCR.
Results::
We have found statistically significant changes in expression of 193 genes; 22 genes changed in excess of 1.5 -2.0 fold. The majority of differentially enriched transcripts belonged to ESTs, some of which potentially represent novel genes. Among known genes, we identified functional clusters implicated in crucial neuronal processes, such as potassium transport, nerve impulse transmission and neurogenesis using network analyses. We also tested differentially enriched genes for association with age related and neurological disorders. This analysis revealed genes associated with ALS, arteriosclerosis, Alzheimer’s and Parkinson’s diseases.
Conclusions::
In this work we demonstrated feasibility of genome-wide gene expression profiling for studies of neuronal aging using easily accessible RGCs as a model. 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. These genes represent candidates of pathways associated with age-related increases in vulnerability to stress.
Keywords: aging • ganglion cells • gene microarray