Ontology highlight
ABSTRACT:
PROVIDER: PRJNA260386 | ENA |
REPOSITORIES: ENA
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Project description:DNA methylation is an important component of epigenetic modifications that influences the transcriptional machinery and is aberrant in many human diseases. Several methods have been developed to map DNA methylation for either limited regions or genome-wide. In particular, antibodies specific for methylated CpG have been successfully applied in genome-wide studies. However, despite the relevance of the obtained results, the interpretation of antibody enrichment is not trivial. Of greatest importance, the coupling of antibody-enriched methylated fragments with microarrays generates DNA methylation estimates that are not linearly related to the true methylation level. Here, we present an experimental and analytical methodology to obtain enhanced estimates which better describe the true values of DNA methylation level throughout the genome. We propose an experimental scenario for evaluating the true relationship in a high-throughput setting and a model-based analysis to predict the absolute and relative DNA methylation levels. We successfully applied this model to evaluate DNA methylation status of normal human melanocytes compared to a melanoma cell strain. Despite the low resolution typical of methods based on immunoprecipitation, we show that model-derived estimates of DNA methylation provide relatively high correlation with measured absolute and relative levels, as validated by bisulfite genomic DNA sequencing. Importantly, the model-derived DNA methylation estimates simplify the interpretation of the results both at single-loci and at chromosome-wide levels. The MEDME R library as well as installation instructions and a PDF tutorial are available online at the website below.
2008-07-21 | GSE12096 | GEO
Project description:Methylated DNA enrichment is a key step in a microarray based genome-wide methylation profiling study, and even for future high-throughput sequencing based methylome analysis. In order to evaluate the sensitivity and accuracy of methylated DNA enrichment, we investigated and optimized a number of important parameters to improve the performance of several enrichment assays, including differential methylation hybridization (DMH), microarray-based methylation assessment of single samples (MMASS), and methylated DNA immunoprecipitation (MeDIP). With advantages and disadvantages unique to each approach, we found that assays based on methylation-sensitive enzyme digestion and those based on immunoprecipitation detected different methylated DNA fragments, indicating that they are complementary in their relative ability to detect methylation differences. Our study provides the first comprehensive evaluation for widely used methodologies for methylated DNA enrichment, and could be helpful for developing a cost effective approach for DNA methylation profiling.
2010-01-22 | GSE19974 | GEO
Project description:The development of whole-genome bisulfite sequencing (WGBS) has led to a number of exciting discoveries about how genomes utilize DNA methylation and has led to a plethora of novel testable hypotheses. Methods for constructing sodium bisulfite-converted and amplified libraries have recently excelled to the point that the bottleneck for experiments that use WGBS has shifted to data analysis and interpretation. Here we present empirical evidence for an over-representation of methylated DNA from WGBS. This enrichment for methylated DNA is exacerbated by higher cycles of PCR and is influenced by the type of uracil-insensitive DNA polymerase used for amplifying the sequencing library. Future efforts to computationally correct for this enrichment bias will be essential to increasing the accuracy of determining methylation levels for individual cytosines. MethylC-Seq of Arabidopsis thaliana
2014-09-11 | E-GEOD-58217 | biostudies-arrayexpress
Project description:Aim: We aim to compare current (MeDIP-seq), new (Illumina Infinium 450K BeadChip) and future (PacBio) methods for whole genome DNA methylation analysis. As the interest in determination of disease methylation profiles increases, the scope, advantages and limitations of these methods requires assessment. There are key questions to answer and specific challenges to overcome. For example, how much detail/resolution is sufficient to identify regions of differential methylation and regions of biological/medical significance within a sample? How much coverage of the genome is required for accurate methylation analysis? Is it important to confirm which regions of the genome are unmethylated in addition to focusing on those that are methylated? Loss of methylation may be of equal importance within the cell since this may also contribute to disease pathogenesis. A multi-method (affinity enrichment/bisulphite-conversion based/direct sequencing of methyl-cytosine) and technology platform (Illumina HiSeq/PacBio/Illumina Infinium BeadChip) comparison will enable us to determine the strengths and weakness of each method. We propose to compare four methods using two DNA samples from the Coriell Institute for Cell Repository to assess both current and future capabilities for whole genome methylation analysis in parallel: A) MeDIP-seq using Illumina HiSeq B) Illumina Infinium HumanMethylation 450K BeadChip and C) whole genome methylation sequencing using PacBio. Existing single molecule deep bisulphite sequencing data generated previously from these same samples at the WTSI for targeted regions (30-40 genes) on the human X chromosome will be used to assess performance of each method. The methods selected for this study will generate data covering a range of resolutions from a whole genome scan to array (target defined) resolution and up to single base pair, single molecule resolution; the highest level of detail possible with methods currently available.Samples: DNA from sibling pair GM01240 (female) and GM01240 (male).Requirements: Both samples will be analysed using;A.MeDIP-seq using Illumina HiSeq (one HiSeq lane, 75bp paired end, per sample) B.Illumina Infinium HumanMethylation 450K BeadChipWe are expecting a potentially unnecessary high coverage using one HiSeq lane per sample. However, for the MeDIP procedure we do not have a multiplexing procedure in place. Our requirements for PacBio sequencing have been discussed with and will be supported by the Sequencing Technology Development group.
2013-01-22 | E-ERAD-139 | biostudies-arrayexpress
Project description:The vertebrate body plan and organs are shaped during a highly conserved embryonic phase called the phylotypic stage, however the mechanisms that guide the epigenome through this transition and their evolutionary conservation remain elusive. Here we report widespread DNA demethylation of thousands of enhancers during the phylotypic period in zebrafish, Xenopus and mouse. These dynamic enhancers are linked to essential developmental genes that display coordinated transcriptional and epigenomic changes in the diverse vertebrates during embryogenesis. Phylotypic stage-specific binding of Tet proteins to (hydroxy)methylated DNA, and enrichment of hydroxymethylcytosine on these enhancers, implicated active DNA demethylation in this process. Furthermore, loss of function of Tet1/2/3 in zebrafish caused reduced chromatin accessibility and increased methylation levels specifically on these enhancers, indicative of DNA methylation being an upstream regulator of phylotypic enhancer function. Overall, our study reveals a novel regulatory module associated with the most conserved phase of vertebrate embryogenesis and uncovers an ancient developmental role for the Tet dioxygenases.
2016-01-27 | PXD001164 | Pride
Project description:DNA methylation plays critical roles in gene regulation and cellular specification without altering DNA sequences. The wide application of reduced representation bisulfite sequencing (RRBS) and whole genome bisulfite sequencing (bis-seq) opens the door to study DNA methylation at single CpG site resolution. One challenging question is how best to test for significant methylation differences between groups of biological samples in order to minimize false positive findings. Current methods to analyze genome-wide bisulfite sequencing data use a smoothing approach or a simple statistical test based on the binomial distribution. Comparative DNA methylation profiling in AML blasts and normal CD34(+) control cells
2014-08-22 | E-GEOD-55569 | biostudies-arrayexpress
Project description:DNA methylation is a mechanism for long-term transcriptional regulation and is required for normal cellular differentiation. Failure to properly establish or maintain DNA methylation patterns leads to cell dysfunction and diseases such as cancer. Identifying DNA methylation signatures in complex tissues can be challenging due to inaccurate cell enrichment methods and low DNA yields. We have developed a technique called Laser Capture Microdissection-Reduced Representation Bisulfite Sequencing (LCM-RRBS) for the multiplexed interrogation of the DNA methylation status of CpG Islands and promoters. LCM-RRBS accurately and reproducibly profiles genome-wide methylation of DNA extracted from microdissected fresh frozen or formalin-fixed paraffin-embedded tissue samples. To demonstrate the utility of LCM-RRBS, we characterized changes in DNA methylation associated with gonadectomy-induced adrenocortical neoplasia in the mouse. Compared to adjacent normal tissue, the adrenocortical tumors showed reproducible gains and losses of DNA methylation at genes involved in cell differentiation and organ development. LCM-RRBS is a rapid, cost-effective, and sensitive technique for analyzing DNA methylation in heterogeneous tissues and will facilitate the investigation of DNA methylation in cancer and organ development. Laser capture microdissection-reduced representation bisulfite sequencing and reduced representation bisulfite sequencing on human blood leukocyte, human endometrial tumor, mouse liver tissue, and mouse normal and neoplastic adrenal tissue
2013-03-21 | E-GEOD-45361 | biostudies-arrayexpress
Project description:We used two RNA-Seq methods to measure the the global transcription levels in mouse liver cells. The data here provide insight into the pros and cons of whole transcript method and 3' RNA-Seq method.
2018-10-24 | GSE116949 | GEO
Project description:DNA methylation was measured by MBD2 enrichment of DNA fragments in IMR90. A statistical model was developed to estimate absolute methylation levels, and compared to whole genome bisulfite sequencing results (Lister, R. et al. (2009) Human DNA methylomes at base resolution show widespread epigenomic differences. Nature) Two techincal replicates of MBD2 methylated DNA enrichment in IMR90 cells.
2012-11-30 | E-GEOD-38679 | biostudies-arrayexpress