Examination of four human tissue samples by MethylC-seq
Ontology highlight
ABSTRACT: As genome-scale DNA methylation sequencing technologies have improved it has become apparent that tissue-specific methylation can occur not only at promoters, enhancers, and CpG islands but also over larger genomic regions. In most human tissues, the vast majority of the genome is highly methylated (>70%). However, genomic sequencing of bisulfite-treated DNA (MethylC-seq) has revealed large partially methylated domains (PMDs) in some human cell lines. However, to date only cultured cells and some cancers have shown evidence for PMDs, suggesting that PMDs may not be observed in normal human tissues. Here we performed MethylC-seq in a set of human tissues and found that full-term human placenta shows clear evidence of PMDs.
Project description:As genome-scale DNA methylation sequencing technologies have improved it has become apparent that tissue-specific methylation can occur not only at promoters, enhancers, and CpG islands but also over larger genomic regions. In most human tissues, the vast majority of the genome is highly methylated (>70%). However, genomic sequencing of bisulfite-treated DNA (MethylC-seq) has revealed large partially methylated domains (PMDs) in some human cell lines. However, to date only cultured cells and some cancers have shown evidence for PMDs, suggesting that PMDs may not be observed in normal human tissues. Here we performed MethylC-seq in a set of human tissues and found that full-term human placenta shows clear evidence of PMDs. Examination of four human tissue samples by MethylC-seq, with one tissue (placenta) having a technical replicate (taken from same placenta) and two additional biological replicates (from different placentas)
Project description:As genome-scale DNA methylation sequencing technologies have improved it has become apparent that tissue-specific methylation can occur not only at promoters, enhancers, and CpG islands but also over larger genomic regions. In most human tissues, the vast majority of the genome is highly methylated (>70%). However, genomic sequencing of bisulfite-treated DNA (MethylC-seq) has revealed large partially methylated domains (PMDs) in some human cell lines. However, to date only cultured cells and some cancers have shown evidence for PMDs, suggesting that PMDs may not be observed in normal human tissues. Here we performed MethylC-seq in a set of human tissues and found that full-term human placenta shows clear evidence of PMDs.
Project description:As genome-scale DNA methylation sequencing technologies have improved it has become apparent that tissue-specific methylation can occur not only at promoters, enhancers, and CpG islands but also over larger genomic regions. In most human tissues, the vast majority of the genome is highly methylated (>70%). However, genomic sequencing of bisulfite-treated DNA (MethylC-seq) has revealed large partially methylated domains (PMDs) in some human cell lines. However, to date only cultured cells and some cancers have shown evidence for PMDs, suggesting that PMDs may not be observed in normal human tissues. Here we performed MethylC-seq in a set of human tissues and found that full-term human placenta shows clear evidence of PMDs. Examination of gene expression in human placenta using RNA-seq, with one biological replicate (taken from same placenta)
Project description:DNA methylation is essential for embryonic and neuronal differentiation, but the function of most genomic DNA methylation marks are poorly understood. Generally the human genome is highly methylated (>70%) except for CpG islands and gene promoters. However, it was recently shown that the IMR90 human fetal lung fibroblast cells have large regions of the genome with partially methylated domains (PMDs, <70% average methylation), in contrast to the rest of the genome which is in highly methylated domains (HMDs, >70% average methylation). Using bisulfite conversion followed by high-throughput sequencing (MethylC-seq), we discovered that human SH-SY5Y neuronal cells also contain PMDs. We developed a novel hidden Markov model (HMM) to computationally map the genomic locations of PMDs in both cell types and found that autosomal PMDs can be over 9 Mb in length and cover 41% of the IMR90 genome and 19% of the SH-SY5Y genome. Genomic regions marked by cell line specific PMDs contain genes that are expressed in a tissue-specific manner, with PMDs being a mark of repressed transcription. Genes contained within N-HMDs (neuronal HMDs, defined as a PMD in IMR90 but HMD in SH-SY5Y) were significantly enriched for calcium signaling, synaptic transmission and neuron differentiation functions. Autism candidate genes were enriched within PMDs and the largest PMD observed in SH-SY5Y cells marked a 10 Mb cluster of cadherin genes with strong genetic association to autism. Our results suggest that these large-scale methylation domain maps could be relevant to interpreting and directing future investigations into the elusive etiology of autism. Examined DNA methylation in a human neuronal cell line and cerebral cortex
Project description:DNA methylation is essential for embryonic and neuronal differentiation, but the function of most genomic DNA methylation marks are poorly understood. Generally the human genome is highly methylated (>70%) except for CpG islands and gene promoters. However, it was recently shown that the IMR90 human fetal lung fibroblast cells have large regions of the genome with partially methylated domains (PMDs, <70% average methylation), in contrast to the rest of the genome which is in highly methylated domains (HMDs, >70% average methylation). Using bisulfite conversion followed by high-throughput sequencing (MethylC-seq), we discovered that human SH-SY5Y neuronal cells also contain PMDs. We developed a novel hidden Markov model (HMM) to computationally map the genomic locations of PMDs in both cell types and found that autosomal PMDs can be over 9 Mb in length and cover 41% of the IMR90 genome and 19% of the SH-SY5Y genome. Genomic regions marked by cell line specific PMDs contain genes that are expressed in a tissue-specific manner, with PMDs being a mark of repressed transcription. Genes contained within N-HMDs (neuronal HMDs, defined as a PMD in IMR90 but HMD in SH-SY5Y) were significantly enriched for calcium signaling, synaptic transmission and neuron differentiation functions. Autism candidate genes were enriched within PMDs and the largest PMD observed in SH-SY5Y cells marked a 10 Mb cluster of cadherin genes with strong genetic association to autism. Our results suggest that these large-scale methylation domain maps could be relevant to interpreting and directing future investigations into the elusive etiology of autism.
Project description:Tissue specific DNA methylation is present across many genomic elements, including large genomic regions. Most human tissues posses highly methylated genomes (>70%), but recent data has suggested the presence of partially methylated domains (PMDs) in some cell-lines. Placenta is a unique human tissue which has very different molecular properties than most tissues. It is the aim of this study to identify the presence/absence of PMDs in placental tissue and further define the DNA methylation landscape of the placenta. In particular this experiment is designed to look at the placental methylome across gestational ages in chromosome 21 to detect methylomic differences throughout development.
Project description:Over the last 20-80 million years the mammalian placenta has taken on a variety of morphologies through both divergent and convergent evolution. Recently we have shown that the human placenta genome has a unique epigenetic pattern of large partially methylated domains (PMDs) and highly methylation domains (HMDs) with gene body DNA methylation positively correlating with level of gene expression. In order to determine the evolutionary conservation of DNA methylation patterns and transcriptional regulatory programs in the placenta, we performed a genome-wide methylome (MethylC-seq) analysis of human, rhesus macaque, squirrel monkey, mouse, dog, horse, and cow placentas as well as opossum extraembryonic membrane. We found that, similar to human placenta, mammalian placentas and opossum extraembryonic membrane have globally lower levels of methylation compared to somatic tissues. However, not all species have clear PMD/HMDs in their placentas. Instead what is conserved is higher methylation over the bodies of genes involved in mitosis, vesicle-mediated transport, protein phosphorylation, and chromatin modification compared with the rest of the genome. As in human placenta, high gene body methylation is associated with higher gene expression across species. Analysis of DNA methylation in mouse and cow oocytes shows the same pattern of gene body methylation over many of the same genes as in the placenta, suggesting that this conserved pattern of active gene body methylation of the placenta may be established very early in development. MethylC-seq on placentas of 7 mammals, trophoblasts of rhesus, brains of 3 mammals, oocytes of cow, and human cordblood
Project description:Using MethylC-Seq to provide single-base resolution of DNA methylation status in idm2 single mutant and idm1idm2 double mutant MethylC-Seq: 2 mutants examined, idm2 single mutant (two biological replicates) and idm1idm2 double mutant