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S. Genini, W. A. Beltran, B. Zangerl, G. D. Aguirre; Up-Regulation of Expression of Genes Belonging to the Tumor Necrosis Factor (TNF) Superfamily in RPGR-ORF15 Frameshift Mutant Retina. Invest. Ophthalmol. Vis. Sci. 2010;51(13):1687.
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© ARVO (1962-2015); The Authors (2016-present)
To identify genes and pathways associated with retinal degeneration in dogs affected with XLPRA2, a canine model of early-onset XLRP caused by a RPGR exon ORF15 microdeletion.
Comparisons between mutant and normal retinas (3/group/age) were performed at 3, 7, and 16 wks using canine custom real-time PCR arrays containing 96 gene-specific TaqMan assays (ABI). Of these, 93 belong to known relevant apoptotic and anti-apoptotic pathways, while 3 are housekeeping genes. Ct values for each gene were normalized with the averaged median values of GAPDH and ACTB, and the ratio of diseased vs. control calculated with the DDCt method. Statistical analyses were computed with RealTime StatMiner (Integromics), including a parametric moderated t-test with significance set at p<0.05 (Benjamini-Hochberg adjusted) and fold change >1.5.
None of the genes were significantly altered at 3 wks. At 7 and 16 wks, 22 and 34 genes, respectively, were differentially expressed (DE). Of these, 19 were the same at the two ages. Except OPN1SW and XIAP (16 wks) and RHO (both ages), all the DE genes were up-regulated in mutant retinas compared to normals. Several genes of the TNF superfamily were over-expressed, including FASLG, TNFα, TNFRSF1α, TNFSF8, and TRADD at both ages, and FAS, TNFRSF9, TNFSF10, and TRAF3 at 16 wks. Besides the pro-inflammatory TNF-α, other cytokines/chemokines, e.g. IL10, IL6, and CCL2, were also abundantly over-expressed in diseased retinas.
Relevant apoptosis-related genes involved in XLPRA2 pathogenesis at different crucial ages were identified. Results indicate that at early disease stage (induction phase-3 wks) expression differences were not present, while at both 7 (cell death peak) and 16 wks (decreased but persistent execution phase) common pathways which are mainly mediated by genes of the TNF superfamily contribute to the observed retinal degeneration. Additional genes not included on the array are currently under evaluation, as well as validation at the protein level.
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