Detection of aberrant DNA methylation in undifferentiated and differentiated human ES cells compared to normal fetal tissues
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens
SUBMITTER: Deborah Nejman
PROVIDER: E-GEOD-24270 | biostudies-arrayexpress |
REPOSITORIES: biostudies-arrayexpress
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Project description:Embryonic stem cells can be differentiated in vitro to produce a variety of somatic cell types. We have employed the mDIP method combined with hybridization to a CpG islend microarray . We show that this differentiation is accompanied by an intrinsic process of extensive aberrant CpG island de novo methylation that includes developmental and cancer target genes. CpG-methylated genomic DNA was enriched using a methyl-DNA immunoprecipitation (mDIP) assay. DNA from the input and bound (enriched) DNA for each sample were labeled and hybridized on the array to define the methylation state of each region.
2014-02-05 | E-GEOD-54664 | biostudies-arrayexpress
Project description:Following erasure in the early animal embryo, a new bimodal DNA methylation pattern is regenerated at the time of implantation in each individual through a wave of generalized de novo modification with CpG islands specifically left unmethylated. In this paper, we ask whether CpG islands are M-bM-^@M-^\protectedM-bM-^@M-^] from de novo methylation or, alternatively, acquire their unmodified state through M-bM-^@M-^\demethylation.M-bM-^@M-^] Using a genetic approach, we demonstrate that ES cells indeed have the ability to specifically demethylate CpG islands through pathways involving hydroxymethylation (Tet1), deamination (Aid), glycosylation (Mbd4) and excision repair (Gadd45a) genes. Surprisingly, this demethylation system is not actually necessary for generating the overall bimodal methylation pattern in ES cells. This general activity does, however, appear to be involved both in somatic cell reprogramming, as well as the normal methylation reprogramming that takes place in the early embryo. CpG-methylated genomic DNA was enriched using a methyl-DNA immunoprecipitation (mDIP) assay. DNA from the input and bound (enriched) DNA for each sample were labeled and hybridized on the array to define the methylation state of each region.
2013-11-17 | E-GEOD-48923 | biostudies-arrayexpress
Project description:De novo methylation of CpG islands is seen in many tumors, but the general rules governing this process are not known. By analyzing DNA from tumors, as well as normal tissues, and by utilizing a wide range of published data, we have been able to identify a well-defined set of tumor targets, each of which has its own M-bM-^@M-^\coefficientM-bM-^@M-^] of methylation that is largely determined by its inherent relative ability to recruit the polycomb complex. This pattern is initially formed by a slow process of de novo methylation that occurs during aging and then undergoes expansion early in tumorigenesis, where it may play a role as an inhibitor of development-associated gene activation. We also demonstrate that DNA methylation patterns can be used to diagnose the primary tissue source of tumor metastases. CpG-methylated genomic DNA was enriched using a methyl-DNA immunoprecipitation (mDIP) assay. DNA from the input and bound (enriched) DNA for each sample were labeled and hybridized on the array to define the methylation state of each region.
2014-03-26 | E-GEOD-38142 | biostudies-arrayexpress
Project description:Colorectal carcinoma (CRC) is often characterized by chromosomal instability (CIN) which has been associated with a poor prognosis. Disease-related de novo methylation often causes gene repression that may complement chromosomal losses or mutations. To compare CpG island methylation and chromosomal abnormalities in colorectal cancer, we determineded unbalanced chromosomal changes by aCGH of CRCs that were also profiled for aberrant de novo DNA methylation at 23,000 CpG islands of the human genome (Gebhard et al. 2010; and unpublished data). Refer to individual Series. This SuperSeries is composed of the following subset Series: GSE25221: CpG island methylation in colorectal cancer GSE25228: Chromosomal abnormalities in colorectal cancer
2012-11-01 | E-GEOD-25229 | biostudies-arrayexpress
Project description:To globally define methylation-M-bM-^@M-^YproneM-bM-^@M-^Y and -M-bM-^@M-^YprotectedM-bM-^@M-^Y CpG islands in cancer, we analyzed the methylation status of 23,000 CpG islands of the human genome in 19 colorectal carcinoma samples as well as normal colon using our previously described methyl-CpG immunoprecipitation (MCIp) technique (Gebhard et al. 2006; Schilling and Rehli 2007). This method enriches for highly CpG methylated DNA that can be directly applied to fluorescent labeling and oligonucleotide microarray hybridization without an additional amplification step. CpG-methylated genomic DNA was enriched using methyl-CpG immunoprecipitation (MCIp). On each microarray, the enriched material from colorectal carcinoma samples was compared to the enriched material from normal colon to identify aberrantly methylated regions.
2012-11-01 | E-GEOD-25221 | biostudies-arrayexpress
Project description:Using glutathione peroxidase, Gpx1 and Gpx2, double knockout (Gpx1/2-KO) mice as a model of inflammatory bowel disease predisposing to intestinal cancer, we analyzed genome-wide DNA methylation and chromatin changingM-bM-^@M-^Ys in the mouse ileum during chronic inflammation, aging and cancer. We found that inflammation leads to aberrant DNA methylation in Polycomb target genes, with 70% of the ~250 genes methylated in the inflamed tissue being PcG targets in embryonic stem cells and 58% of the methylated genes being marked by H3K27 trimethylation in the ileum of adult wildtype mice. Acquisition of DNA methylation at CpG islands in the ileum of Gpx-1/2-KO mice frequently correlated with loss of H3K27 trimethylation at the same loci. Inflammation-associated DNA methylation occurs preferentially in tissue-specific silent genes and, importantly, is much more frequently represented in tumors than is age-dependent DNA methylation. 60% of aberrant methylation found in tumors is also present in the inflamed tissue. In summary, inflammation creates a signature of aberrant DNA methylation, which is observed later in the malignant tissue and is directed by the PcG complex. In our study we used mice Gpx1/2-ko with B6 and B6.129 genetic background which are characterized by different level of inflammation in ileum and different tumor susceptibility. DNA methylation was analyzed by using MIRA-assisted Microarrays approach. Changing of the DNA methylation in intestinal epithelium during inflammation and tumorgenesis in Gpx1/2-KO mice were compared to healthy control mice with matching age. Aged dependent DNA methylation was study by comparing DNA methylation between 28-days-old healthy control mice with 8-month-old mice. To detect DKO-specific DNA methylation, we compared the changing DNA methylation in liver from Gpx1/2-KO mice with liver from control mice at age 28 days and 8 month. Association of the inflammation dependent DNA methylation with Polycomb targets and loss of H3K27me3 were verified by ChIp-on-ChIp experiments using H3K27me3 antibodies.
2008-12-31 | E-GEOD-12315 | biostudies-arrayexpress
Project description:Abstract: DNA methylation is an essential epigenetic modification that plays a key role associated with the regulation of gene expression during differentiation but in disease states such as cancer, the DNA methylation landscape is often deregulated. There are now numerous technologies available to interrogate DNA methylation status of CpG sites in a targeted or genome-wide fashion but each method, due to intrinsic biases, potentially interrogates different fractions of the genome. In this study, affinity-purification of methylated DNA using two popular genome-wide techniques: methylated DNA immunoprecipitation (MeDIP) and methyl-CpG binding domain-based capture (MBDCap) were evaluated, highlighting that each technique operates in a different domain of the CpG density landscape. The effect of whole genome amplification was explored, illustrating that it can reduce sensitivity for detecting DNA methylation in GC-rich regions of the genome. Using MBDCap, microarray- and sequencing-based readouts were compared, highlighting the impact that copy number variation (CNV) can make in differential comparisons of methylomes. These studies reveal that the analysis of DNA methylation data and genome coverage is highly dependent on the method employed and consideration must be made in light of GC content, extent of DNA amplification and copy number. Comparison of MeDIP/MBD for DNA methylation profiling, comparison of whole genome amplification techniques, using tiling array for copy number aberration detection and comparisons of tiling array data to sequencing readouts
2010-10-08 | E-GEOD-24546 | biostudies-arrayexpress
Project description:We applied a combination of Methyl-CpG Immunoprecipitation (MCIp) and Human CpG Island microarrays to identify aberrant DNA methylation in eight low-grade breast invasive carcinomas and two pre-invasive breast tumors against ten normal breast tissues. 10 breast tumor samples (8 invasive, 2 pre-invasive) and 10 normal breast tissues, paired randomly (except Array 10: matched pair)
2012-09-14 | E-GEOD-35263 | biostudies-arrayexpress
Project description:DNA methyltransferase I plays the central role in maintenance of CpG DNA methylation patterns across the genome and alteration of CpG methylation patterns is a frequent and significant occurrence across many cancers. Cancer cells carrying hypomorphic alleles of Dnmt1 have become important tools for understanding Dnmt1 function and CpG methylation. In this study, we analyse colorectal cancer cells with a homozygous deletion of exons 3 to 5 of Dnmt1, resulting in reduced Dnmt1 activity. Although this cell model has been widely used to study the epigenome, the effects of the Dnmt1 hypomorph on cell signalling pathways and the wider proteome are largely unknown. In this study, we perform the first quantitative proteomic analysis of this important cell model and identify multiple signalling pathways and processes that are significantly dysregulated in the hypomorph cells. In Dnmt1 hypomorph cells, we observed a clear and unexpected signature of increased Epithelial-to-Mesenchymal transition (EMT) markers as well as reduced expression and sub-cellular re-localization of Beta-Catenin. Expression of wild-type Dnmt1 in hypomorph cells or knock-down of wild-type Dnmt1 did not recapitulate or rescue the observed protein profiles in Dnmt1 hypomorph cells suggesting that hypomorphic Dnmt1 causes changes not solely attributable to Dnmt1 protein levels. In summary we present the first comprehensive proteomic analysis of the widely studied Dnmt1 hypomorph colorectal cancer cells and identify redistribution of Dnmt1 and its interaction partner Beta-Catenin
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Project description:Osteoarthritis (OA) is a chronic disease of the joint characterized by a progressive degradation of articular cartilage and subchondral bone. In healthy tissue, specialized cells called chondrocytes are regulating a balanced cartilage catabolism and anabolism. By contrast osteoarthritic joints are characterized by a dramatic increase of cartilage catabolism, due to changes of gene expression patterns within chondrocytes. To identify potential epigenetic differences regulating this process a genome-wide methylation screening of paired unaffected and osteoarthritic knee cartilage samples was performed. Therefore samples of macroscopic arthritic and non-arthritic cartilage areas of the femoral condyle of five female patients were collected and DNA isolation was performed. For being able to investigate methylation changes on a genome-wide scale using only limited amounts of DNA a specific amplification protocol for mainly methylated DNA has been established, based on combinations of different methylation-sensitive and M-bM-^@M-^Sindependent restriction digestions. The amplified DNA was then labeled and hybridized onto Agilent M-bM-^@M-^\Human Promoter Whole GenomeM-bM-^@M-^] microarrays. A random variance t-test for paired (per patient) samples was performed, identifying 1214 differentially methylated genetic targets between arthritic and non-arthritic samples. The biological relevance of these genes was then further investigated via Gene Ontology (GO) and KEGG pathway analysis. DNA isolated of paired arthritic and non-arthritic knee cartilage samples of five different female osteoarthritis patients (10 samples) was methylation-specifically amplified using combinations of methylation-sensitive and -insensitive restriction enzymes. Amplicons were dye labeled (Cy3) and hybridized onto 2x244k Agilent Human Promoter microarrays.
2014-07-01 | E-GEOD-48422 | biostudies-arrayexpress