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F.W. Rozsa, D.M. Reed, K.M. Scott, T. Guckian Kijek, J.E. Richards; Gene Expression Changes in Dexamethasone–Induced Human Trabecular Meshwork Cells by Donor Age . Invest. Ophthalmol. Vis. Sci. 2006;47(13):1867.
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© ARVO (1962-2015); The Authors (2016-present)
Use of dexamethasone is associated with steroid induced–glaucoma and cultured trabecular meshwork (TM) cells show dramatic changes in gene expression in response to dexamethasone. We compare gene expression responses to dexamethasone between TM cells from young and old donors to evaluate whether responses to dexamethasone change during aging.
Cultured fifth passage human TM cell lines from three young donors (12, 16, 17 y.o.) and one older donor (49 y.o.) with no history of glaucoma were untreated or treated with 100 nM DEX for 21 days. Gene expression was determined using triplicate Affymetrix U133A GeneChips. Microarrays were analyzed using MAS 5.1 software. Data from a list of 52 genes that produced statistically significant changes greater than three–fold across all three young cell lines were compared to data for those same genes from the old donor. Validation of microarray data and pathway assignment of significantly changed genes will also be discussed.
DEX treatment resulted in a minimum three–fold increase (31 genes) or decrease (21 genes) in all three young cell TM cell lines, with assay of the older TM cell line showing significant increases among 21 of those genes and significant decreases among 6 of those genes. Five genes (CH13L1, CP, PCSK1, IL1R2, MT1K) expressed at substantial levels in the younger data set were considered absent in both the untreated and dex–treated cells in the older cell line. The average increase in expression for MYOC in the young samples was 17–fold but produced only a 7–fold increase in the older sample. None of the 52 genes identified in the younger samples had significant, corresponding changes in the opposite direction in the older sample.
Prolonged exposure to DEX significantly alters the expression of more than a thousand genes in the trabecular meshwork in cells from young donors. A subset of genes that show highly significant changes in gene expression behave similarly in an older cell line, but more than 10% of the genes of that showed substantial signal levels and signal changes in the young data set are not expressed under either condition in the old cell line. Additional studies using more older individuals are needed to provide statistical power and to evaluate whether some of the observed differences are due to inter–individual variation rather than age.
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