Project description:Our goal was to conduct an integrated gene expression and copy number analysis combining our results from Affymetrix and NimbleGen microarrays. The purpose of the study was to give functional relevance to the copy number events by providing a statistically powerful integrated interpretation of gene expression changes and copy number alterations. See accompaying experiment E-MTAB-946 for details of the expression analyssi.
Project description:Fifteen DNA methylation array experiments were performed on five human chromosome specific array platforms (NimbleGen: HG18_CHR13_FT, HG18_CHR18_FT, HG18_CHR21_FT, HG18_CHRX_FT, HG18_CHRY_FT), comparing: (1) one female whole blood immunoprecipitated DNA fragments to their input DNA, (2) one 1st trimester normal placenta immunoprecipitated DNA fragments to their input DNA and (3) one 3rd trimester normal placenta immunoprecipitated DNA fragments to their input DNA.
Project description:Eukaryotic chromatin is separated into functional domains differentiated by posttranslational histone modifications, histone variants, and DNA methylation. Methylation is associated with repression of transcriptional initiation in plants and animals, and is frequently found in transposable elements. Proper methylation patterns are critical for eukaryotic development, and aberrant methylation-induced silencing of tumor suppressor genes is a common feature of human cancer. In contrast to methylation, the histone variant H2A.Z is preferentially deposited by the Swr1 ATPase complex near 5' ends of genes where it promotes transcriptional competence. How DNA methylation and H2A.Z influence transcription remains largely unknown. Here we show that in the plant Arabidopsis thaliana, regions of DNA methylation are quantitatively deficient in H2A.Z. Exclusion of H2A.Z is seen at sites of DNA methylation in the bodies of actively transcribed genes and in methylated transposons. Mutation of the MET1 DNA methyltransferase, which causes both losses and gains of DNA methylation, engenders opposite changes in H2A.Z deposition, while mutation of the PIE1 subunit of the Swr1 complex that deposits H2A.Z17 leads to genome-wide hypermethylation. Our findings indicate that DNA methylation can influence chromatin structure and effect gene silencing by excluding H2A.Z, and that H2A.Z protects genes from DNA methylation. Keywords: Affinity-purification on microarray All experiments were done using two channels per chip. DNA methylation experiments compared immunoprecipitated, methylated DNA to control genomic DNA. H2A.Z experiments compared whole micrococcal nuclease-treated affinity-purified chromatin to input chromatin used for affinity purification. Affinity purification was performed using either biotin-tagged H2A.Z, pulled down using streptavidin, or endogenous H2A.Z pulled down using an anti-H2A.Z antibody.
Project description:We applied genome-wide profiling to successive salt-extracted fractions of micrococcal nuclease-treated Drosophila chromatin. Chromatin fractions extracted with 80mM or 150mM NaCl after digestion contain predominantly mononucleosomes and represent calssical 'active' chromatin. Profiles of these low-salt-soluble fractions display phased nucleosomes over transcriptionally active genes that are locally depleted of histone H3.3 and correspond closely to profiles of RNA polymerase II. Nearly quantitative recovery of chromatin is obtained with 600mM NaCl, however, the remaining insoluble chromatin is enriched in actively transcribed regions. Salt-insoluble chromatin likely represents oligonucleosomes that are attached to large protein complexes. Both low-salt extracted and insoluble chromatin are rich in sequences that correspond to epigenetic regulatory elements genome-wide. The presence of active chromatin at both extremes of salt solubility suggests that these salt fractions capture bound and unbound intermediates in active processes, thus providing a simple, powerful strategy for mapping epigenome dynamics. Keywords: Chromatin affinity-purification on microarray For data usage terms and conditions, please refer to http://www.genome.gov/27528022 and http://www.genome.gov/Pages/Research/ENCODE/ENCODEDataReleasePolicyFinal2008.pdf All experiments were done using two channels per chip, comparing DNAs extracted from either salt-extracted or insoluble chromatin to whole nuclear chromatin, whole nuclear chromatin to randomly fragmented genomic DNA, streptavidin-bound biotin-tagged histone-variant-containing chromatin to salt-extracted chromatin, gel-purified mononucleosomes to whole EDTA-extracted soluble chromatin, streptavidin-bound biotin-tagged histone-variant-containing chromatin to whole EDTA-extracted soluble chromatin, or oligo(dT)-primed cDNA to randomly fragmented genomic DNA from S2 cell nuclei.
Project description:Methylated modifications of genome are common events in carcinogenesis and is involved in the tumorigenesis and progression of various cancers including gastric cancer Methylated DNA immunoprecipitation (MeDIP) combined with a human miRNA tiling microarray analysis demonstrated that there are much methylation differention between gastric cancers and adjacent controls microRNA gene methylation comparison of 3 pairs of gastric cancer and controls
Project description:Pancreatic ductal adenocarcinoma (PDAC) is a highly invasive cancer with a poor prognosis. Using methylated DNA immunoprecipitation (MeDIP)-chip analysis, we found that 161 genes that were specifically hypermethylated in PANC-1 cells. Among them, miR-615-5p was hypermethylated in its putative promoter region, which silenced its expression in PDAC cell lines. Comparison between PANC-1 cell lines and normal pancreas tissue
Project description:We have undertaken a detailed study to identify expression polymorphism of NCRs. We used a custom Affymetrix oligonucleotide microarray to examine the expression changes of 566 NCRs in four different accessions of Medicago truncatula. Each accession was inoculated with two different rhizobial strains to assess the NCR expression differences caused by host-symbiont specificity. The NCRs displayed significant expression differences among the ecotypes but had subtle differences in gene expression because of strain difference. We used a custom Affymetrix chip containing 684 probe sequences of Medicago DEFLs to explore the expression polymorphism of NCRs in nodules inoculated with Sinorhizobium meliloti 1021(Sm1021) and Sinorhizobium medicae (SmA321) totalling 8 different treatments. Each treatment was supported by three biological replicates giving a grand total of 24 samples.
Project description:DNA methylation is an epigenetic mark associated with transposable element silencing and gene imprinting in flowering plants and mammals. In plants, imprinting occurs in the endosperm, which nourishes the embryo during seed development. We have profiled Arabidopsis DNA methylation genome-wide in the embryo and endosperm. Large-scale methylation changes accompany endosperm development and endosperm-specific gene expression. Transposable element fragments are extensively demethylated in the endosperm. We discovered new imprinted genes by identifying candidate genes associated with the top differentially methylated regions. Our data suggest that imprinting in plants evolved from genome defense against transposable elements. Keywords: Affinity-purification on microarray All experiments were done using two channels per chip. Immunoprecipitated methylated DNA (IP) was compared to control genomic DNA (input). Both the IP and input represent Cy5 and Cy3 labeled Illumina GA libraries.