Unknown,Transcriptomics,Genomics,Proteomics

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Gene expression profile in CD4+ and CD8+ T cells from identical twins discordant for Multiple sclerosis

ABSTRACT: To gain insight into the etiopathogenesis of Multiple sclerosis (MS) we investigated gene expression changes in CD4+ and CD8+ T lymphocytes from monozygotic twins (MZ) discordant for relapsing remitting MS. We studied 4 monozygotic twin pairs discordant for disease, with the affected co-twin free of disease modifying therapies (F/M = 3/1, mean age 36.25±3.9). Following leukapheresis, CD4+ and CD8+ T cells were separated and studied by Affymetrix GeneChip® For gene expression profiling, peripheral blood mononuclear cell (PBMC) were obtained from leukopheresis by density centrifugation over Ficoll-hypaque according to standard procedures. Briefly, heparinized blood was diluted with 1 volume of RPMI medium and gently layered over the Fycoll. Following centrifugation at 660 g for 30 minutes, cells at the interface of the gradient was collected and washed 3 times. Highly purified CD4+ and CD8+ (purity >95%) cell subsets were then sorted by flow cytometry on MoFlo high speed cell sorter (Beckman Coulter, Fullerton, CA) and frozen in Trizol (Invitrogen). Total RNA was extracted using TRIzol® (Invitrogen), according to the manufacturer's instructions. RNA quality and purity were assessed with the use of the RNA 6000 Nano assay on Agilent 2100 Bioanalyzer (Agilent). Total RNA from each sample was prepared using GeneChip® one Cycle cDNA Synthesis kit and GeneChip® IVT Labeling kit (Affymetrix), according to the manufacturer’s protocols. Briefly, starting from 2.5µg total RNA, biotinylated cRNA was produced by one cycle of reverse transcription and in vitro transcription (IVT). Biotinylated cRNA was fragmented and hybridized for 16 h at 45°C onto GeneChip® Human Genome U133 Plus 2.0 arrays (Affymetrix). The statistical analysis was performed couple by couple using the Rosetta Resolver® system (Rosetta Biosoftware). The fold-change of each gene was calculated by comparing gene expression in the affected twin with that in the unaffected twin and the genes with the same trend in at least 3 twin pairs out of the 4 studied were selected as candidates to be validated by real-time RT-PCR.

ORGANISM(S): Homo sapiens

SUBMITTER: Viviana Annibali

PROVIDER: E-GEOD-16461 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Autism is currently considered a multigene disorder with epigenetic influences. To investigate the contribution of DNA methylation to autism spectrum disorders, we have recently completed large-scale methylation profiling by CpG island microarray analysis of lymphoblastoid cell lines (LCL) derived from monozygotic twins discordant for diagnosis of autism and their nonautistic siblings. Methylation profiling revealed many candidate genes differentially methylated between discordant MZ twins as well as between both twins and nonautistic siblings. Bioinformatics analysis of the differentially methylated genes demonstrated enrichment for high level functions including gene transcription, nervous system development, cell death/survival, and other biological processes implicated in autism. The methylation status of two of these candidate genes, BCL-2 and retinoic acid receptor (RAR)-related orphan receptor alpha (RORA), was further confirmed by bisulfite sequencing and methylation-specific PCR, respectively. Immunohistochemical analyses of tissue arrays containing slices of the cerebellum and frontal cortex of autistic and age- and sex-matched control subjects revealed decreased expression of RORA and BCL-2 proteins in the autistic brain. Our data thus confirm the role of epigenetic regulation of gene expression via differential DNA methylation in idiopathic autism, and furthermore link molecular changes in a peripheral cell model with brain pathobiology in autism. Global methylation profiling was performed on lymphoblastoid cell lines (LCLs) derived from three pairs of male monozygotic twins discordant for diagnosis of autism as determined by the Autism Diagnostic Interview-Revised (ADI-R). As controls, cell lines derived from non-autistic siblings of two pairs of twins were also included in the analyses, in addition to cell lines derived from a set of monozygotic twins unaffected by autism. For all paired analyses, a direct comparison was performed in which the methylation-enriched fractions from two individuals were pooled and hybridized onto the same microarray. In addition, indirect comparisons were performed by co-hybridizing the methylation-enriched (MIRA) fraction with the respective unenriched DNA fraction obtained from the same individual. For each paired analysis (between autistic MZ twins and/or between autistic co-twin and unaffected sibling), a total number of 4 replicates were performed, including direct and indirect comparisons.

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Gene expression profile in CD4+ and CD8+ T cells from identical twins discordant for Multiple sclerosis

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