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D. Wang, A. Ray, C. Ergorul, W. Huang, C. L. Grosskreutz; Gene Expression Profiling in Rat Retinal Ganglion Cells After Experimental Elevation of Intraocular Pressure. Invest. Ophthalmol. Vis. Sci. 2008;49(13):5487. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Intraocular pressure (IOP) is an important risk factor contributing to glaucomatous retinal ganglion cell (RGC) damage. We studied gene expression changes in rat RGC after experimental IOP elevation to elucidate the molecular mechanisms of RGC death.
RGCs were bilaterally back-labeled by stereotaxic injection of Fluorogold into the superior colliculus. Sustained unilateral IOP elevation was produced by hypertonic saline episcleral vein injection in Brown Norway rats (Morrison model) with the fellow eye serving as a control (n = 3). Using laser capture microdissection (LCM), an equal number of RGCs were captured from both eyes. RNA was extracted and then amplified, labeled and hybridized to Affymetrix rat genome 230 2.0 arrays. Microarray data analysis was performed using dChip. Biological pathway analysis of expression data was conducted by GenMAPP.
There were 1157 genes differently expressed (fold change ≥ 2), including 661 genes up-regulated and 776 genes down-regulated. These genes mainly are involved in apoptosis, calcium regulation and TGFβ signaling pathway. Nrg1, Map2k1, Nrn1, Vsnl1, Rgs4, Ywhaz, Stmn2, Ret, Ywhab, Nell2, Calb2 and Grb2, genes that are categorized as neurogenesis and survival genes (are expressed predominantly in RGCs of normal Brown Norway rats: Ivanov D et al., FEBS Lett, 2006. 580(1): p. 331-5), were significantly down-regulated in RGCs from eyes with high IOP.
Our results suggest that elevated IOP leads to specific changes in RGCs resulting in downregulation of pro-survival genes. The activation of calcium regulation pathways and TGFβ signaling pathway may also contribute to glaucomatous RGC damage. We demonstrate in this work that the technique of combining LCM with Affymetrix microarray analysis may provide clues to understand the specific molecular pathways underlying RGC death in glaucoma.
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