Unknown,Transcriptomics,Genomics,Proteomics

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Gene expression of the whole mouse eye

ABSTRACT: Background Age-related macular degeneration (AMD) is the leading cause of irreversible blindness in the elderly population worldwide. Recent studies have demonstrated strong genetic associations between AMD and single nucleotide polymorphisms (SNPs) within genes such as CFH and HTRA1. However, we have identified monozygotic twins discordant for AMD phenotypes (one with disease, the other without disease), suggesting that an epigenetic mechanism may also contribute to the pathogenesis of AMD. Methods We identified two twin pairs with phenotypic discordance of AMD. We obtained genomic DNA from their peripheral blood mononuclear cells (PBMCs) and subjected them to DNA methylation-chip analysis (MeDIP-chip) that profiled genome-wide DNA methylation patterns on promoters of all genes and microRNAs. We next utilized the Methyl-Profiler DNA methylation assays to detect the methylation status of selected promoters. Flow cytometry and quantitative real-time PCR were used to detect the expression of the selected gene in peripheral blood cells, as well as in retinal and choroidal tissues of AMD patients and non-AMD controls. Results Our MeDIP-chip analysis identified 256 genes with hypo-methylated promoters only in the twins with AMD and 744 genes with hyper-methylated promoters only in the twins with AMD. Importantly, the promoter region of IL17RC was associated with hypo-methylated CpG sites only in the twins with AMD but not in the twins without AMD. We also found the association of the hypo-methylated IL17RC promoter with AMD in 7 pairs of siblings with discordant AMD pathology (P=0.003), as well as an independent patient cohort (95 neovascular wet and 107 geographic atrophy dry AMD patients as well as 96 non-AMD controls (95% CI, 0.01-0.10, P=9.8x10-8 for wet AMD vs. control; 95% CI, 0.05-0.32, P=2.2x10-5 for dry AMD vs. control)). Interestingly, we did not find an association between the levels of methylation on the IL17RC promoter with the previously identified genetic risk alleles in CFH, HTRA1, and ARMS2. We demonstrated an elevated expression of the IL-17RC protein in CD14+ monocytes in the peripheral blood of AMD patients as compared to non-AMD controls. These IL-17RC+ monocytes have elevated expression of CXCR1, CXCR2, and CXCR4. In addition, IL17RC was expressed only in the retinal and choroidal tissues from AMD patients but not from age-matched controls. Conclusions We show an association of the hypo-methylated IL17RC promoter with AMD, which resulted in the elevated expression of IL-17RC in peripheral blood cells as well as the retinal and choroidal tissues of AMD patients. Our study suggests that the hypo-methylated IL17RC promoter and elevated expression of IL-17RC can potentially serve as biomarkers for the diagnosis of AMD, while IL-17RC can be a new therapeutic target for AMD. In addition, our results strongly suggest an epigenetic control mechanism of AMD pathogenesis. The Affymetrix MOE430 2.0 GeneChip was used to detect gene expression patterns within the whole eye of C57B/6 normal mice.

ORGANISM(S): Mus musculus

SUBMITTER: Lai Wei

PROVIDER: E-GEOD-28002 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Background Age-related macular degeneration (AMD) is the leading cause of irreversible blindness in the elderly population worldwide. Recent studies have demonstrated strong genetic associations between AMD and single nucleotide polymorphisms (SNPs) within genes such as CFH and HTRA1. However, we have identified monozygotic twins discordant for AMD phenotypes (one with disease, the other without disease), suggesting that an epigenetic mechanism may also contribute to the pathogenesis of AMD. Methods We identified two twin pairs with phenotypic discordance of AMD. We obtained genomic DNA from their peripheral blood mononuclear cells (PBMCs) and subjected them to DNA methylation-chip analysis (MeDIP-chip) that profiled genome-wide DNA methylation patterns on promoters of all genes and microRNAs. We next utilized the Methyl-Profiler DNA methylation assays to detect the methylation status of selected promoters. Flow cytometry and quantitative real-time PCR were used to detect the expression of the selected gene in peripheral blood cells, as well as in retinal and choroidal tissues of AMD patients and non-AMD controls. Results Our MeDIP-chip analysis identified 256 genes with hypo-methylated promoters only in the twins with AMD and 744 genes with hyper-methylated promoters only in the twins with AMD. Importantly, the promoter region of IL17RC was associated with hypo-methylated CpG sites only in the twins with AMD but not in the twins without AMD. We also found the association of the hypo-methylated IL17RC promoter with AMD in 7 pairs of siblings with discordant AMD pathology (P=0.003), as well as an independent patient cohort (95 neovascular wet and 107 geographic atrophy dry AMD patients as well as 96 non-AMD controls (95% CI, 0.01-0.10, P=9.8x10-8 for wet AMD vs. control; 95% CI, 0.05-0.32, P=2.2x10-5 for dry AMD vs. control)). Interestingly, we did not find an association between the levels of methylation on the IL17RC promoter with the previously identified genetic risk alleles in CFH, HTRA1, and ARMS2. We demonstrated an elevated expression of the IL-17RC protein in CD14+ monocytes in the peripheral blood of AMD patients as compared to non-AMD controls. These IL-17RC+ monocytes have elevated expression of CXCR1, CXCR2, and CXCR4. In addition, IL17RC was expressed only in the retinal and choroidal tissues from AMD patients but not from age-matched controls. Conclusions We show an association of the hypo-methylated IL17RC promoter with AMD, which resulted in the elevated expression of IL-17RC in peripheral blood cells as well as the retinal and choroidal tissues of AMD patients. Our study suggests that the hypo-methylated IL17RC promoter and elevated expression of IL-17RC can potentially serve as biomarkers for the diagnosis of AMD, while IL-17RC can be a new therapeutic target for AMD. In addition, our results strongly suggest an epigenetic control mechanism of AMD pathogenesis.

Project description:We report the application of MeDIP sequencing technology for high-throughput profiling of M2 and M1 phenotype U937 cells. A total of 260 differentially methylated regions (DMRs) within promotor regions were identified, with 191 hyper-methylated and 69 hypo-methylated every chromosome. These DMRs were then further examined using GO analysis, with the top10 most enriched GO terms for both the hyper- and hypo-methylation groups isolated. The processes associated with hyper-methylation included the regulation of protein processes (targeting, processing, maturation and localization) and tyrosine phosphorylation of STAT5 protein, while the hypo-methylated processes included the regulation of epithelial to mesenchymal transition, mesenchymal cell differentiation and epithelial to mesenchymal transition. When further analyzing the regulation of tyrosine STAT5 phosphorylation, three associated genes (IL-31RA, IL-3, and NF2) previous shown to be associated with tumor or cancer development were also identified, thus suggesting that hyper-methylation may be important during M2 polarization into M1 cells. The epithelial to mesenchymal transition (EMT) process has been long accepted to be associated with cancer metastasis and malignance. Herein, four genes (TGFB1I1, TWIST1, HPN, and PHLDB2) that have been previously reported to participate in cancer invasion and metastasis were hypo-methylated during the EMT process, thus suggesting that these hypo-methylation sites might be a potential therapeutic target to control cancer metastasis. Moreover, the hyper-methylation was found to be predominantly localized to membranes, including the leading edge membrane, whole membrane, endoplasmic reticulum-Golgi intermediate compartment membrane, recycling endosome membrane and ruffle membrane, whereas the hypo-methylation was predominantly localized to the cytoskeleton, cell junction and cell cortex. These findings also suggest a potential ability for epigenetic therapy due to both the membrane and cytoskeleton being feasible targets for therapeutic chemical or antibody targeting. When performing pathway enrichment analysis for the hyper-methylated genes, fatty acid biosynthesis, ubiquitin mediated proteolysis, mRNA surveillance and AMPK signaling pathways were enriched; while for the hypo-methylated genes, pathways associated with cancers, such as tight junction, VEGF signaling, cAMP signaling, proteoglycans and Ras signaling pathways were enriched during polarization from M2 to M1 cells

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Gene expression of the whole mouse eye

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