Targeted bisulfite sequencing by solution hybrid selection and massively parallel sequencing
Ontology highlight
ABSTRACT: We applied the solution hybrid selection approach to the enrichment of CpG islands (CGIs) and promoter sequences from the human genome for targeted high-throughput bisulfite sequencing. A single lane of Illumina sequences allowed accurate and quantitative analysis of 1 million CpGs in more than 21,408 CGIs and 15,946 transcriptional regulatory regions. More than 85% of capture probes successfully yielded quantitative DNA methylation information of targeted regions. In this study, we generated genome-wide, single-base resolution DNA methylation maps in three of the most commonly used breast cancer cell lines.Differentially methylated regions (DMRs) were identified in the 5?-end regulatory regions, as well as the intra- and intergenic regions, particularly in the X chromosome among the three cell lines. The single CpG resolution methylation maps of many known tumor suppressor genes were also established in the three cell lines.
Project description:We applied the solution hybrid selection approach to the enrichment of CpG islands (CGIs) and promoter sequences from the human genome for targeted high-throughput bisulfite sequencing. A single lane of Illumina sequences allowed accurate and quantitative analysis of 1 million CpGs in more than 21,408 CGIs and 15,946 transcriptional regulatory regions. More than 85% of capture probes successfully yielded quantitative DNA methylation information of targeted regions. In this study, we generated genome-wide, single-base resolution DNA methylation maps in three of the most commonly used breast cancer cell lines.Differentially methylated regions (DMRs) were identified in the 5?-end regulatory regions, as well as the intra- and intergenic regions, particularly in the X chromosome among the three cell lines. The single CpG resolution methylation maps of many known tumor suppressor genes were also established in the three cell lines. Here we present a novel approach that combines solution-phase hybrid selection and massively parallel bisulfite sequencing to profile DNA methylation in targeted CGI and promoter regions. We designed 51,466 single strand DNA oligonucleotides (160-mer) which target 23,441 CGIs and the transcription start sites of 19,369 known genes in the human genome. The synthetic long DNA oligonucleotides were converted into biotinylated RNA probes for solution-phase hybridization capture of target DNA. The captured genomic DNA was treated with sodium bisulfite, amplified by PCR and sequenced using Illumina GA IIx sequencer.
Project description:We report the application of single molecule-based sequencing technology in combination with CXXC affinity purifcation (CAP-seq), MBD affinity purification (MAP-seq) and chromatin immunoprecipitation (ChIP-seq) to generate reciprocal methylation and chromatin modifcation maps in human and mouse. We find that contrary to sequence based prediction methods that humans and mice possess highly equivalent compliments of CpG islands (CGIs). The majority of these CGIs are positive for the active histone modification; H3K4me3 in embryonic stem cells (ES cells) the magnitude of which is correlated with the local density of non-methylated CpG. Approximately half of the human and mouse CGIs are distal to annotated gene promoters, yet more than 40% identify unanticipated transcription start sites as defined by RNA polymerase occupancy and published RNA mapping data. These orphans CGIs preferentially acquire DNA methylation in somatic cells, and this corresponds with a loss of H3K4me3 and RNA polymerase II at these sites. Conversely abnormal CGI methylation found in colorectal tumours showed a distinct distribution relative to that found in normal somatic tissues displaying preferential association with loci marked by H3K27me3 in human ES cells. This study provides a comprehensive functional assessment of CGIs in normal and diseased tissues. Examination of CGI methylation status in human and mouse primary tissues.
Project description:Human and mouse genomes contain a similar number of CpG islands (CGIs), which are discrete CpG-rich DNA sequences associated with transcription start sites. In both species, about 50% of all CGIs are remote from annotated promoters, but nevertheless often have promoter-like features. To document the role of CGI methylation in cell differentiation, we analysed DNA methylation at a comprehensive CGI set in cells of the mouse hematopoietic lineage. Using a method that potentially detects ~33% of genomic CpGs in the methylated state (>7 million) we found that large differences in gene expression were accompanied by surprisingly few DNA methylation changes. There were, however, many DNA methylation differences between hematopoietic cells and a distantly related tissue, brain. Altered DNA methylation occurred predominantly at CGIs within gene bodies, which have the properties of cell type-restricted promoters, but infrequently at annotated gene promoters or CGI flanking sequences. Elevated intragenic CGI methylation correlated with silencing of the associated gene. Differentially methylated intragenic CGIs tended to lack H3K4me3 and associate with a transcriptionally repressive environment regardless of methylation state. Our results indicate that DNA methylation changes play a relatively minor role in the late stages of differentiation, but point to a distinct role for intragenic CGIs. Mouse immune cells (dendritic cells, B cells, CD4 T cells, Th1 and Th2 cells) were isolated and DNA methylation and gene expression profiled. Methylation and expression patterns were compared to those in brain. For gene expression analysis three biological replicates were used for each cell type.
Project description:We report the application of single molecule-based sequencing technology in combination with CXXC affinity purifcation (CAP-seq), MBD affinity purification (MAP-seq) and chromatin immunoprecipitation (ChIP-seq) to generate reciprocal methylation and chromatin modifcation maps in human and mouse. We find that contrary to sequence based prediction methods that humans and mice possess highly equivalent compliments of CpG islands (CGIs). The majority of these CGIs are positive for the active histone modification; H3K4me3 in embryonic stem cells (ES cells) the magnitude of which is correlated with the local density of non-methylated CpG. Approximately half of the human and mouse CGIs are distal to annotated gene promoters, yet more than 40% identify unanticipated transcription start sites as defined by RNA polymerase occupancy and published RNA mapping data. These orphans CGIs preferentially acquire DNA methylation in somatic cells, and this corresponds with a loss of H3K4me3 and RNA polymerase II at these sites. Conversely abnormal CGI methylation found in colorectal tumours showed a distinct distribution relative to that found in normal somatic tissues displaying preferential association with loci marked by H3K27me3 in human ES cells. This study provides a comprehensive functional assessment of CGIs in normal and diseased tissues.
Project description:In this study, we screened human placental samples for allele-specific methylation and subsequently novel imprinted genes associated with these regions. We used reduced representation bisulfite sequencing to identify partially methylated CpG islands (CGIs) in the human placental genome. We were able to delineate potential candidates for allele-specific methylation based on the calculation of a concordance statistic. Amongst the 28 regions chosen for validation based on high levels of expression, two regions were shown to exhibit allele-specific expression. Single base-resolution methylation analysis in the placental genome and RNA-Seq
Project description:While the majority of RNA polymerase II initiation events in mammalian genomes take place within CpG island (CGI) promoters, our understanding of their regulation remains limited. Here we combine single-molecule footprinting with interaction proteomics to identify BANP as a critical CGI regulator and the long sought-after TF that binds the orphan CGCG element in mouse and human. We show that BANP drives the activity of essential metabolic genes in the mouse genome in pluripotent and terminally differentiated cells. However, BANP binding is strongly repelled by DNA methylation of its motif in vitro and in vivo, which epigenetically restricts most binding to CGIs and accounts for its absence at aberrantly methylated CGIs in cancer cells. Upon binding to an unmethylated motif, BANP opens chromatin and phases nucleosomes. Our results establish Banp as a critical activator and put forth a model whereby CGI promoter activity relies on methylation-sensitive TFs capable of chromatin opening.
Project description:Human and mouse genomes contain a similar number of CpG islands (CGIs), which are discrete CpG-rich DNA sequences associated with transcription start sites. In both species, about 50% of all CGIs are remote from annotated promoters, but nevertheless often have promoter-like features. To document the role of CGI methylation in cell differentiation, we analysed DNA methylation at a comprehensive CGI set in cells of the mouse hematopoietic lineage. Using a method that potentially detects ~33% of genomic CpGs in the methylated state (>7 million) we found that large differences in gene expression were accompanied by surprisingly few DNA methylation changes. There were, however, many DNA methylation differences between hematopoietic cells and a distantly related tissue, brain. Altered DNA methylation occurred predominantly at CGIs within gene bodies, which have the properties of cell type-restricted promoters, but infrequently at annotated gene promoters or CGI flanking sequences. Elevated intragenic CGI methylation correlated with silencing of the associated gene. Differentially methylated intragenic CGIs tended to lack H3K4me3 and associate with a transcriptionally repressive environment regardless of methylation state. Our results indicate that DNA methylation changes play a relatively minor role in the late stages of differentiation, but point to a distinct role for intragenic CGIs.
Project description:Human and mouse genomes contain a similar number of CpG islands (CGIs), which are discrete CpG-rich DNA sequences associated with transcription start sites. In both species, about 50% of all CGIs are remote from annotated promoters, but nevertheless often have promoter-like features. To document the role of CGI methylation in cell differentiation, we analysed DNA methylation at a comprehensive CGI set in cells of the mouse hematopoietic lineage. Using a method that potentially detects ~33% of genomic CpGs in the methylated state (>7 million) we found that large differences in gene expression were accompanied by surprisingly few DNA methylation changes. There were, however, many DNA methylation differences between hematopoietic cells and a distantly related tissue, brain. Altered DNA methylation occurred predominantly at CGIs within gene bodies, which have the properties of cell type-restricted promoters, but infrequently at annotated gene promoters or CGI flanking sequences. Elevated intragenic CGI methylation correlated with silencing of the associated gene. Differentially methylated intragenic CGIs tended to lack H3K4me3 and associate with a transcriptionally repressive environment regardless of methylation state. Our results indicate that DNA methylation changes play a relatively minor role in the late stages of differentiation, but point to a distinct role for intragenic CGIs.
Project description:Fertilization triggers a global erasure of 5-methylcytosine from paternal DNA as part of extensive epigenetic reprogramming during the transition from gametic specialization to totipotency. This active removal has been shown to involve oxidation by TET3, but the targeting of this pathway and the wider context of demethylation remain poorly understood. We optimized a novel technique for whole-genome bisulfite sequencing and applied it to wild-type and TET3-deficient zygotes, using SNPs to access paternal alleles. As the great majority of sperm-contributed methylation lies outside the CpG islands (CGIs) and promoters analysed to date, these genome-wide methylation profiles allow paternal methylation trajectories in the zygote to be comprehensively examined for the first time. This global view revealed that in addition to pervasive loss of methylation from intergenic sequences and most repetitive elements, gene bodies constitute a major target of zygotic demethylation. Methylation loss is associated with zygotic genome activation, and at gene bodies is also linked to increased transcriptional noise in the early embryo. Our data maps the primary contribution of oxidative demethylation to a subset of gene bodies and single-copy intergenic sequences, and implicates the action of redundant pathways at many loci. We further uncover a novel function for TET3 in protection from de novo methylation at CGIs and promoters. This work adds new breadth to our understanding of the molecular events involved in reprogramming gametic identity following fertilization. Three independent collections of zygotes were performed for each genotype (control and TET3 deletion), giving a total of 225 control and 237 TET3 deletion zygotes, of which 120 and 129 were derived from 129S2/SvHsd studs for control and TET3 samples, respectively. Zygotes were pooled and whole-genome bisulfite libraries were prepared using a post-bisulfite adaptor tagging strategy optimized from (Miura et al. Nucleic Acids Research 2012, 40:e136)
Project description:Human and mouse genomes contain a similar number of CpG islands (CGIs), which are discrete CpG-rich DNA sequences associated with transcription start sites. In both species, about 50% of all CGIs are remote from annotated promoters, but nevertheless often have promoter-like features. To document the role of CGI methylation in cell differentiation, we analysed DNA methylation at a comprehensive CGI set in cells of the mouse hematopoietic lineage. Using a method that potentially detects ~33% of genomic CpGs in the methylated state (>7 million) we found that large differences in gene expression were accompanied by surprisingly few DNA methylation changes. There were, however, many DNA methylation differences between hematopoietic cells and a distantly related tissue, brain. Altered DNA methylation occurred predominantly at CGIs within gene bodies, which have the properties of cell type-restricted promoters, but infrequently at annotated gene promoters or CGI flanking sequences. Elevated intragenic CGI methylation correlated with silencing of the associated gene. Differentially methylated intragenic CGIs tended to lack H3K4me3 and associate with a transcriptionally repressive environment regardless of methylation state. Our results indicate that DNA methylation changes play a relatively minor role in the late stages of differentiation, but point to a distinct role for intragenic CGIs. Mouse immune cells (dendritic cells, B cells, CD4 T cells, Th1 and Th2 cells) were isolated and DNA methylation and gene expression profiled. Methylation and expression patterns were compared to those in brain. DNA methylation was profiled using MAP-seq and two replicates were carried out for each cell type of interest.