Cytosine methylation at CpCpG sites triggers accumulation of non-CpG methylation in gene bodies
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ABSTRACT:
ORGANISM(S): Arabidopsis thaliana
PROVIDER: GSE89913 | GEO | 2017/01/04
SECONDARY ACCESSION(S): PRJNA354264
REPOSITORIES: GEO
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Project description:As a key epigenetic modification, DNA methylation is essential for normal development by regulating processes like gene expression, genomic imprinting, and suppression of repetitive elements. However, DNA methylation in the cattle genome is not well understood. Here we presented the first single-base-resolution maps of DNA methylation in 10 diversely somatic tissues harvested from the sequenced Hereford cow L1 Dominette 01449 and her relatives using reduced representation bisulphite sequencing (RRBS). In total, we observed 1,868,049 high accuracy cytosines that located in the CG enriched regions. Similar to the methylation patterning in other species, the CG context was predominant methylated. Widespread differences were identified between the methylation patterns of CG and non-CG contexts. They were distributed differentially among the genomic features, including the genic regions, CpG islands, and repetitive sequences. Autocorrelation analysis among adjacent residues illustrated that methylation level of CGs were highly correlated in a region. In contrast, weak or no correlation was found among non-CGs or between CGs and non-CGs. The distinct distribution and low correlation of CG and non-CG methylation suggested that non-CG methylation may be independent from CG methylation and may be mediated by different mechanisms. We also detected 798 tissue-specific differentially methylated cytosines (tDMC) and 131 tissue-specific differentially methylated CpG islands. Combined analysis with the RNA-seq data, we discovered several non-CGs in tDMCs also highly correlated with gene expression, which implied the potential function of non-CG methylation in somatic cells in addition to pluripotent cells. In summary, we showed that non-CGs exist in bovine tissues and some of them were correlated with tissue-specific functions. This study provided essential information for the cytosine methylation patterning in bovine somatic tissues.
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Project description:As a key epigenetic modification, DNA methylation is essential for normal development by regulating processes like gene expression, genomic imprinting, and suppression of repetitive elements. However, DNA methylation in the cattle genome is not well understood. Here we presented the first single-base-resolution maps of DNA methylation in 10 diversely somatic tissues harvested from the sequenced Hereford cow L1 Dominette 01449 and her relatives using reduced representation bisulphite sequencing (RRBS). In total, we observed 1,868,049 high accuracy cytosines that located in the CG enriched regions. Similar to the methylation patterning in other species, the CG context was predominant methylated. Widespread differences were identified between the methylation patterns of CG and non-CG contexts. They were distributed differentially among the genomic features, including the genic regions, CpG islands, and repetitive sequences. Autocorrelation analysis among adjacent residues illustrated that methylation level of CGs were highly correlated in a region. In contrast, weak or no correlation was found among non-CGs or between CGs and non-CGs. The distinct distribution and low correlation of CG and non-CG methylation suggested that non-CG methylation may be independent from CG methylation and may be mediated by different mechanisms. We also detected 798 tissue-specific differentially methylated cytosines (tDMC) and 131 tissue-specific differentially methylated CpG islands. Combined analysis with the RNA-seq data, we discovered several non-CGs in tDMCs also highly correlated with gene expression, which implied the potential function of non-CG methylation in somatic cells in addition to pluripotent cells. In summary, we showed that non-CGs exist in bovine tissues and some of them were correlated with tissue-specific functions. This study provided essential information for the cytosine methylation patterning in bovine somatic tissues.
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Project description:DNA methylation plays an important role in development and disease. The primary sites of DNA methylation in vertebrates are cytosines in the CpG dinucleotide context, which account for roughly three quarters of the total DNA methylation content in human and mouse cells. While the genomic distribution, inter-individual stability and functional role of CpG methylation are reasonably well understood, little is known about DNA methylation targeting CpA, CpC and CpT dinucleotides. Here we report a comprehensive analysis of non-CG methylation in 72 genome-scale DNA methylation maps across human pluripotent and differentiated cell types. We confirm non-CG methylation to be predominant in pluripotent cell types and observe an expected decrease upon differentiation and near complete absence in various differentiated cells. Our data highlight that non-CG methylation is highly variable and shows little conservation between different pluripotent cell lines. While we show a strong correlation of non-CG methylation and DNMT3 expression levels we find a statistical independence of non-CG methylation from pluripotency associated gene expression. Finally, non-CG methylation appears to be spatially correlated with CpG methylation. In summary these results contribute further to our understanding of DNA methylation in human cells and help clarify previous observations using a large representative sample set. Examination of nonCG DNA methylation patterns in pluripotent and differentiated cells
2011-08-31 | E-GEOD-27432 | biostudies-arrayexpress
Project description:Cytosine DNA methylation is a heritable epigenetic mark present in many eukaryotic organisms. While DNA methylation likely has a conserved role in gene silencing, the levels and patterns of DNA methylation appear to vary drastically among different organisms. Here, we used shotgun genomic bisulfite sequencing (BS-Seq) to compare DNA methylation in eight diverse plant and animal genomes. We found that patterns of methylation are very similar in flowering plants with methylated cytosines detected in all sequence contexts, whereas CG methylation predominates in animals. Vertebrates have methylation throughout the genome except for CpG islands. Gene body methylation is conserved with clear preference for exons in most of the organisms. Furthermore, genes appear to be the major target of methylation in Ciona and honeybee. Among the eight organisms, the green alga Chlamydomonas has the most unusual pattern of methylation, having non-CG methylation enriched in exons of genes rather than in repeats and transposons. In addition, we demonstrate that the Dnmt1 cofactor Uhrf1 has a conserved function in maintaining CG methylation in both transposons and gene bodies in the mouse, Arabidopsis, and zebrafish genomes. Comparison of methylation across eight eukaryotic organisms
2010-04-09 | E-GEOD-21152 | biostudies-arrayexpress
Project description:DNA methylation plays an important role in development and disease. The primary sites of DNA methylation in vertebrates are cytosines in the CpG dinucleotide context, which account for roughly three quarters of the total DNA methylation content in human and mouse cells. While the genomic distribution, inter-individual stability and functional role of CpG methylation are reasonably well understood, little is known about DNA methylation targeting CpA, CpC and CpT dinucleotides. Here we report a comprehensive analysis of non-CG methylation in 72 genome-scale DNA methylation maps across human pluripotent and differentiated cell types. We confirm non-CG methylation to be predominant in pluripotent cell types and observe an expected decrease upon differentiation and near complete absence in various differentiated cells. Our data highlight that non-CG methylation is highly variable and shows little conservation between different pluripotent cell lines. While we show a strong correlation of non-CG methylation and DNMT3 expression levels we find a statistical independence of non-CG methylation from pluripotency associated gene expression. Finally, non-CG methylation appears to be spatially correlated with CpG methylation. In summary these results contribute further to our understanding of DNA methylation in human cells and help clarify previous observations using a large representative sample set.
2011-09-01 | GSE27432 | GEO
Project description:DNA methylation (mC) on CpG sites is the most common epigenetic modification. Recently methylation on non-CpG context was found to widely occur on genomic DNA. However, how non-CpG methylation influences DNA/protein interaction and regulates transcription is unknown. Using single-molecule assays, we studied the interactions of transcription factors (TFs) GR, ER and BMAL1-CLOCK with methylated or unmethylated cognate DNA binding sequences. The results demonstrated that these TFs interact with methylated DNA discriminatively. We then performed BisChIP-seq with GR and BMAL1-CLOCK in HEK-293T cells and showed that they can recognize and bind to the methylated sites within chromatin. The effects of non-CpG methylation on transcriptional regulation were validated by in vitro transcription assays with correlated RNA level, and further studied mechanistically by crystallographic analyses and molecular dynamics simulations. We conclude that the non-CpG methylation of DNA provides another general mechanism for regulating gene expression through affecting TFs binding affinity.
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Project description:In diverse eukaryotes, constitutively silent sequences, such as transposons and repeats, are marked by methylation at histone H3 lysine 9 (H3K9me). Despites the conservation and importance in the genome integrity, mechanisms to exclude H3K9m from active genes remained largely unexplored. Here we show in Arabidopsis that the exclusion depends on a histone demethylase gene, IBM1 (increase in BONSAI methylation); loss-of-function ibm1 mutation caused ectopic H3K9me in thousands of genes, which accompanies genic DNA methylation at non-CG sites. The ibm1-induced genic H3K9me depended on both histone methylase KYP/SUVH4 and DNA methylase CMT3, suggesting interdependence of two epigenetic marks – H3K9me and non-CG methylation. Notably, IBM1 enhanced loss of H3K9m in transcriptionally de-repressed sequences. Furthermore, disruption of transcription in genes induced ectopic non-CG methylation, mimicking the loss of IBM1 function. We propose that active chromatin is stabilized by the autocatalytic loop of transcription and H3K9 demethylation. This process counteracts accumulation of silent epigenetic marks, H3K9me and non-CG methylation, which is also autocatalytic.
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Project description:This data was generated by ENCODE. If you have questions about the data, contact the submitting laboratory directly (Florencia Pauli mailto:fpauli@hudsonalpha.org). If you have questions about the Genome Browser track associated with this data, contact ENCODE (mailto:genome@soe.ucsc.edu). This track is produced as part of the ENCODE project. The track displays the methylation status of specific CpG dinucleotides in the given cell types as identified by the Illumina Infinium Human Methylation 450 Bead Array platform (http://www.illumina.com/products/methylation_450_beadchip_kits.ilmn). In general, methylation of CpG sites within a promoter causes silencing of the gene associated with that promoter. The Infinium Human Methylation 450 platform uses bisulfite treated genomic DNA to assay the methylation status of more than 450,000 CpG sites covering all designatable RefSeq genes, including promoter, 5' and 3' regions, without bias against those lacking CpG islands. Additionally, the assay includes CpG islands and shores, CpG sites outside of CpG islands, non-CpG methylated sites identified in human stem cells, differentially methylated sites identified in tumor versus normal (multiple forms of cancer) and across several tissue types, CpG islands outside of coding regions, miRNA promoter regions, and disease-associated regions identified through GWAS. Detailed information for the CpG targets is in an CSV formatted spreadsheet in the supplemental directory (http://hgdownload-test.cse.ucsc.edu/goldenPath/hg19/encodeDCC/wgEncodeHaibMethyl450/supplemental/). For data usage terms and conditions, please refer to http://www.genome.gov/27528022 and http://www.genome.gov/Pages/Research/ENCODE/ENCODEDataReleasePolicyFinal2008.pdf Cells were grown according to the approved ENCODE cell culture protocols (http://hgwdev.cse.ucsc.edu/ENCODE/protocols/cell). Genomic DNA was isolated from each cell line with the QIAGEN DNeasy Blood & Tissue Kit according to the instructions provided by the manufacturer. DNA concentrations and a level of quality of each preparation was determined by fluorescence with the Qubit Fluorometer (Invitrogen). Genomic DNA was treated with sodium bisulfite, converting unmethylated cytosines of CpG dinucleotides into uracils; methylated cytosines did not get converted. After bisulfite treatment, the methylation status of a site was assayed by single base-pair extension with a Cy3 or Cy5 labeled nucleotide on oligo-beads specific for the methylated or unmethylated state. The bisulfite conversion reaction was done using the Zymo Research EZ-96 DNA Methylation Kit (http://www.zymoresearch.com/product/ez-96-dna-methylation-kit-d5003). One step of the protocol was modified. During the incubation, a 30 second 95oC denaturing step every hour was included to increase reaction efficiency as recommended by the Illumina Infinium Human Methylation27 protocol. The bead arrays were run according to the protocol provided by Illumina (http://hgdownload-test.cse.ucsc.edu/goldenPath/hg19/encodeDCC/wgEncodeHaibMethyl450/supplemental/wgEncodeHaibMethyl450IlluminaProtocol.pdf). A beta value was calculated for each CpG target with Illumina's Bead Studio software with the Methylation Module v3.2. Beta-value = intensity value from the methylated bead type/(intensity values from the methylated + intensity value from unmethylated bead types + 100). The data was then quality-filtered using p-values. Beta values with p-value greater than 0.01 are considered to fall below the minimum intensity and threshold are displayed as "NA". Any beta value equal to or greater than 0.6 was considered fully methylated. Any beta value equal to or less than 0.2 was considered to be fully unmethylated. Beta values between 0.2 and 0.6 were considered to be partially methylated. Score in the bed files is beta value x 1000
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Project description:Cytosine DNA methylation is a heritable epigenetic mark present in many eukaryotic organisms. While DNA methylation likely has a conserved role in gene silencing, the levels and patterns of DNA methylation appear to vary drastically among different organisms. Here, we used shotgun genomic bisulfite sequencing (BS-Seq) to compare DNA methylation in eight diverse plant and animal genomes. We found that patterns of methylation are very similar in flowering plants with methylated cytosines detected in all sequence contexts, whereas CG methylation predominates in animals. Vertebrates have methylation throughout the genome except for CpG islands. Gene body methylation is conserved with clear preference for exons in most of the organisms. Furthermore, genes appear to be the major target of methylation in Ciona and honeybee. Among the eight organisms, the green alga Chlamydomonas has the most unusual pattern of methylation, having non-CG methylation enriched in exons of genes rather than in repeats and transposons. In addition, we demonstrate that the Dnmt1 cofactor Uhrf1 has a conserved function in maintaining CG methylation in both transposons and gene bodies in the mouse, Arabidopsis, and zebrafish genomes.
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