Selective chemical labeling reveals intragenic enrichment of 5-hydroxymethylcytosine in mouse cerebellum
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ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE25398 | GEO | 2010/12/12
SECONDARY ACCESSION(S): PRJNA134133
REPOSITORIES: GEO
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Project description:5-Methylcytosine (5-mC) is an important DNA modification found in eukaryotes that impacts gene regulation and disease pathogenesis. Recently, 5-hydroxymethylcytosine (5-hmC), another form of DNA modification, has been identified in substantial amounts in certain mammalian cell types; however, its roles as well as its distribution in mammalian genomes are unknown. Here we present a selective chemical labeling method for 5-hmC by utilizing T4 bacteriophage BGT-glucosyltransferase to transfer an engineered glucose moiety containing an azide group onto the hydroxyl group of 5-hmC, which in turn can chemically incorporate a biotin group for detection, affinity enrichment, and sequencing of 5-hmC in mammalian genomes. Using this highly effective method, we demonstrate that 5-hmC is present in human cell lines beyond those previously recognized. We also find a gene expression level-dependent enrichment of intragenic 5-hmC in mouse cerebellum and an age-dependent acquisition of this modification in specific gene bodies linked to neurodegenerative disorders Identification of 5hmC enriched genmoic regions in mouse cerebellum
2010-12-12 | E-GEOD-25398 | biostudies-arrayexpress
Project description:5-methylcytosine (5-mC) can be oxidized to 5-hydroxymethylcytosine (5-hmC). Genome-wide profiling of 5-hmC thus far indicated 5-hmC may not only be an intermediate form of DNA demethylation but could also constitute an epigenetic mark per se. We describe a cost-effective and selective method to detect both the hydroxymethylation and methylation status of cytosines in more than 1.8 million MspI sites in the human genome. This method involves the selective glucosylation of 5-hmC residues, short-sequence tag generation and high-throughput sequencing. We tested this method by screening H9 human embryonic stem cells and their differentiated embroid body cells, and found that differential hydroxymethylation preferentially occur in bivalent genes during cellular differentiation. Especially, our results support hydroxymethylation can regulate key transcription regulators with bivalent marks through demethylation and affect cellular decision on choosing active or inactive state of these genes upon cellular differentiation. We developed a cost-effective and selective method to detect both the hydroxymethylation and methylation status of cytosines in more than 1.8 million MspI sites in the human genome. In this method, we took advantage of the differential enzymatic sensitivities of the isoschizomers MspI and HpaII. HpaII cleaves only a completely unmodified site, any modification at either cytosine blocks the cleavage, while MspI recognizes and cleaves both 5-mC and 5-hmC, but not the newly discovered 5-formylcytosine (5-fC) and 5-carboxylcytosine (5-caC). Furthermore, beta-glucosyltransferase (beta-GT) can transfer a glucose to the hydroxyl group of 5-hmC and generate beta-glucosyl-5-hydroxymethylcytosine (5-ghmC) that blocks MspI digestion. Thus, either by combining beta-GT treatment with MspI digestion or simply applying MspI/HpaII digestion, short sequence tags generated can be used for inferring hydroxymethylation or methylation status in around 1.8 million cytosine sites in the human genome. We tested this method by screening H9 human embryonic stem cells and their differentiated embroid body cells.
2012-12-20 | E-GEOD-41069 | biostudies-arrayexpress
Project description:5-hydroxymethylcytosine (5-hmC), a derivative of 5-methylcytosine (5-mC), is abundant in the brain for unknown reasons. We mapped the genomic distribution of 5-hmC and 5-mC in human and mouse tissues using glucosylation of 5-hmC coupled with restriction enzyme digestion, and interrogation on microarrays. We detected 5-hmC enrichment in genes with synapse-related functions in the brain. We also identified significant, tissue-specific differential distributions of these DNA modifications at the exon-intron boundary, in both human and mouse. This boundary change was mainly due to 5-hmC in the brain, but due to 5-mC in non-neural contexts. This pattern was replicated in multiple independent datasets, and the brain-specific change in 5-hmC was validated using single-molecule sequencing. Moreover, in the brain, constitutive exons contained higher levels of 5-hmC, relative to alternatively-spliced exons. Our study suggests a novel role for 5-hmC in RNA splicing and synaptic function in the brain The M-NM-2-glucosyltransferase (BGT) enzyme transfers a glucose molecule specifically to the hydroxymethyl group of 5-hmC, thus rendering it resistant to digestion by the methylation insensitive MspI enzyme at the ChmCGG target site; 5-hmC is thus detected by differential resistance to MspI-digestion with and without glucosylation of genomic DNA (gDNA). HpaII (targets the same site, CCGG) cannot cut CmCGG or ChmCGG, and conceptually its difference with MspI digestion is a measure of both 5-mC and 5-hmC. Subtraction of 5-hmC from the HpaII-based estimate therefore measures 5-mC. These estimates were measured on respective Affymetrix whole-genome tiling arrays (2.0 R ) MspI - APRIL_fc1.ch02_coverage.bed Undigested DNA - APRIL_fc1.ch01_coverage.bed GluMspI - APRIL_fc1.ch04_coverage_NONTARGET.bed GluMspI - APRIL_fc1.ch04_coverage.bed MspI - APRIL_fc1.ch02_coverage_NONTARGET.bed Undigested DNA - APRIL_fc1.ch01_coverage_NONTARGET.bed MspI - MARCH_fc1.ch02_coverage_NONTARGET.bed Undigested DNA - MARCH_fc1.ch01_coverage_NONTARGET.bed GluMspI - MARCH_fc1.ch04_coverage_NONTARGET.bed GluMspI - MARCH_fc1.ch04_coverage.bed MspI - MARCH_fc1.ch02_coverage.bed Undigested DNA - MARCH_fc1.ch01_coverage.bed MspI - MAY_fc1.ch02_coverage.bed GluMspI - MAY_fc1.ch04_coverage_NONTARGET.bed GluMspI - MAY_fc1.ch04_coverage.bed Undigested DNA - MAY_fc1.ch01_coverage.bed MspI - MAY_fc1.ch02_coverage_NONTARGET.bed Undigested DNA - MAY_fc1.ch01_coverage_NONTARGET.bed
2012-08-24 | E-GEOD-40158 | biostudies-arrayexpress
Project description:5-Hydroxymethyluracil (5hmU) is a thymine modification existing in the genomes of a number of living organisms. The post-replicative formation of 5hmU occurs via hydroxylation of thymine, which can be mediated by the ten-eleven translocation (TET) dioxygenases in mammalian and J-binding proteins (JBPs) in protozoan genomes, respectively. In addition, 5hmU also can be generated through oxidation of thymine by reactive oxygen species or from deamination of 5hmC by activation-induced cytidine deaminase (AID) or APOBEC family enzymes. While the biological roles of 5hmU have not been fully explored, identifying its genomic location will assist in elucidating its functions. Herein, we report a method of enzyme-mediated bioorthogonal labeling to selectively enrich genomic regions containing 5hmU. 5hmU DNA kinase (5hmUDK) was utilized to selectively install an azide group or alkynyl group into the hydroxyl group of 5hmU followed by incorporation of the biotin linker through click chemistry and capture of 5hmU-containing DNA fragments via streptavidin pull-down. The enriched fragments were applied to deep sequencing to map the location of 5hmU. With this established enzyme-mediated bioorthogonal labeling strategy, we achieved the genome-wide mapping of 5hmU in Trypanosoma brucei (T. brucei) genomes. The method described here will allow for a better understanding of the functional roles and dynamics of 5hmU in genomes
2021-07-11 | GSE179809 | GEO
Project description:The method hijacks RNA methyltransferase activity to introduce an alkyne, instead of a methyl, moiety on RNA. Subsequent copper(I)-catalyzed azide–alkyne cycloaddition (CuAAC) with an imidazole-degrader leads to RNA cleavage and degradation, exploiting a mechanism used by endogenous ribonucleases. Focusing on N6-methyladenosine (m6A), we compare Slick-Seq to current state-of-the-art methods used to study of this modification, and show that the platform identifies methylated transcripts, determines RNA methylase specificity, and reliably maps modification sites in intronic and intergenic regions. Importantly, we discovered that METTL16 deposits m6A to intronic polyadenylation (IPA) sites, which suggests a potential role of METTL16 in IPA and, in turn, splicing. Unlike previously reported methods, Slick-Seq allows a comprehensive and dynamic study of RNA modifications throughout the transcriptome, including regions of low abundance.
2020-10-12 | GSE147238 | GEO
Project description:Although rare, the distribution of the 5-hydroxymethylcytosine (hmC) modification in mammalian DNA is tissue- and gene-specific, yet distinct from its repressive methylcytosine (mC) precursor, suggesting unique functions. To examine this possibility, we fractionated mammalian brain extracts to discover binding partners specific for oxidized states of mC. We demonstrate that one such factor, WDR76, is a highly hmC-specific binding protein that modulates gene expression within chromosomal regions enriched in hmC where it binds. In human cell lines and mouse models, WDR76 recruitment by hmC is critical for the initiation and maintenance of MLL-rearranged leukemias. Beyond its canonical role as an intermediate in mC remediation, we show that hmC can be an epigenetic mark whose recognition drives leukemogenesis, portending analogous signaling pathways for other rare DNA modifications.
2021-01-06 | GSE108832 | GEO
Project description:Upon finding that the tetracyclines COL-3 and doxycycline target unique rRNA substructures of the 80S ribosome (E-MTAB-7147), we confirmed these putative ribosomal binding sites by showing that tetracycline-based crosslinking probes are specifically competed from these rRNA structures by their parent drugs. In short, we incorporated dual bioorthogonal handles into tetracycline-based probes, containing both a photoactive diazirine to enable direct probe crosslinking to the human ribosome and an azide handle to allow selective enrichment of crosslinked biomolecules via copper-free ‘click’ chemistry. The COL-3 and doxycycline probes were each incubated with A375 cells, followed by irradiation at 365 nm to induce photolysis of the diazirine moiety and subsequent crosslinking to adjacent ribosomal components. Pulldown and RNA-Seq of the crosslinked RNAs from our experiments were used to identify enrichment of reverse transcription (RT) stops at ribosomal RNA sites caused by local crosslinking of our probes. In these experiments, UV crosslinking was preformed with the COL-3 and doxycycline probe compounds in the presence and absence of free COL-3 and doxycycline (i.e., parent tetracycline molecules lacking the bifunctional diazirine-azide moiety), which were used as competitors to specifically diminish crosslinking to the ribosomal RNA. Crosslinking to ribosomal RNA was determined using RNA-Seq based RT stop enrichment, which was was also compared to inactive tetracycline probes containing a modified bifunctional linker, a non-specific aniline probe, and untreated controls.
2018-08-31 | E-MTAB-7161 | biostudies-arrayexpress
Project description:Background: 5-hydroxymethylcytosine (5-hmC) is a recently discovered epigenetic modification that is altered in cancers. Genome wide assays for 5-hmC determination are needed as many of the techniques commonly used to assay 5-methylcytosine (5-mC), including conventional methyl-sensitive restriction digest and bisulfite sequencing, are incapable of distinguishing between 5-mC and 5-hmC. Results: Glycosylation of 5-hmC residues by beta-Glucosyl Transferase (beta-GT) can make CCGG residues insensitive to digestion by MspI. We used this premise to modify the HELP-tagging assay to identify both 5-mC and 5-hmC loci in the genome. Comparison of sequencing libraries after HpaII, MspI and MspI+ beta-GT conversion resulted in locus specific 5-mC and 5-hmC determination. A custom bioinformatics pipeline was created to identify 5-hmC sites that were validated at global level by LS-MS and the locus specific level by qRT-PCR of 5-hmC pulldown DNA. Hydroxymethylation at both promoter and intragenic locations correlated positively with gene expression. Analysis of pancreatic cancer samples revealed striking redistribution of 5-hmC sites in cancer cells and demonstrated enrichment of this modification at many oncogenic promoters such as GATA6. Conclusions: The HELP-GT assay allows a high resolution, simultaneous determination of 5-hmC and 5-mC loci from small amounts of DNA with the utilisation of modest sequencing resources. Redistribution of 5-hmC seen in cancer highlights the importance of examining this modification in conjugation with conventional methylome analysis. We did methylation and hydroxymethylation tests for one control and two pancreatic cancer cases
2013-07-30 | E-GEOD-42723 | biostudies-arrayexpress
Project description:Enzymatic methylation of cytosine to 5-methylcytosine in DNA is a fundamental epigenetic mechanism involved in mammalian development and disease. DNA methylation is brought about by collective action of three AdoMet-dependent DNA methyltransferases (DNMTs), whose catalytic interactions and temporal interplay are poorly understood. We used structure-guided engineering of the Dnmt1 methyltransferase to enable catalytic transfer of azide tags onto DNA from a synthetic cofactor analog, Ado-6-azide, in vitro . We then CRISPR-edited the Dnmt1 locus in mouse embryonic stem cells to install the engineered codon, which, following pulse- internalization of the Ado-6-azide cofactor by electroporation, permitted selective azide-tagging of Dnmt1-specific genomic targets in cellula . The deposited covalent tags were exploited as ‘click’ handles for reading adjoining sequences and precise genomic mapping of the methylation sites. The proposed approach, Dnmt-TOP-seq, enables high-resolution temporal tracking of the Dnmt1 catalysis in mammalian cells paving the way to selective studies of other methylation pathways in eukaryotic systems.
2022-02-04 | GSE182445 | GEO
Project description:Background: 5-methylcytosine (5-mC) and its oxidized form, 5-hydroxymethylcytosine (5-hmC), are distinct epigenetic marks that help regulate gene expression in the mammalian brain. Existing studies have identified associations between 5-mC and neurodegenerative disease, but little work has examined the potential role of 5-hmC in Parkinson’s disease (PD) or Alzheimer’s disease (AD). Here, we utilized PD postmortem brain tissue and a public dataset from postmortem AD brains to analyze the effect of neurodegenerative disease on paired 5-mC and 5-hmC levels. Results: In PD samples, we measured genome-wide 5-mC and 5-hmC from control (n=3) and PD (n=6) brains using the Illumina EPIC array combined with bisulfite and oxidative bisulfite treatments (BS/oxBS-EPIC). In publicly sourced data, genome-wide 5-mC and 5-hmC were measured from control (n=25) and AD (n=62) human entorhinal cortex tissue using the Illumina 450K array combined with bisulfite and oxidative bisulfite treatment (BS/oxBS-450K). Paired 5-mC and 5-hmC beta values were generated using a custom pipeline of bioinformatics tools, and we modeled the effect of disease on paired 5-mC and 5-hmC data using a mixed effects beta regression model with a random effect for ID and an interaction term between disease category and DNA modification category (“5-mC” or “5-hmC”). We identified a number of CpG probes (AD: n=699, PD: total n = 80) that showed a significant interaction between disease status and DNA modification category (p-value < 2.4x10-7). Conclusions: While our PD data requires additional validation, our analyses suggest that there are widespread shifts in the balance between 5-mC and 5-hmC in Parkinson’s and Alzheimer’s disease.
2019-10-09 | GSE138597 | GEO