Simultaneous measurement of chromatin accessibility, DNA methylation, and nucleosome phasing in single cells
Ontology highlight
ABSTRACT: Gaining insights into the regulatory mechanisms that underlie the pervasive transcriptional variation observed between individual cells necessitates the development of methods that measure chromatin organization in single cells. Nucleosome Occupancy and Methylome-sequencing (NOMe-seq) employs a GpC methyltransferase to detect accessible chromatin and has been used to map nucleosome positioning and DNA methylation genome-wide in bulk samples. Here I provide proof-of-principle that NOMe-seq can be adapted to measure chromatin accessibility and endogenous DNA methylation in single cells (scNOMe-seq). scNOMe-seq recovered characteristic accessibility and DNA methylation patterns at DNase Hypersensitive sites and enabled direct estimation of the number of accessible DHS sites within an individual cell. In addition, scNOMe-seq provided high resolution of chromatin accessibility within individual loci which was exploited to detect footprints of CTCF binding and to estimate the average nucleosome phasing distances in single cells.
Project description:Chromatin accessibility plays a key role in epigenetic regulation of gene activation and silencing. Open chromatin regions allow regulatory elements such as transcription factors and polymerases to bind for gene expression while closed chromatin regions prevent the activity of transcriptional machinery. Nucleosome occupancy and methylome sequencing (NOMe-seq) has been developed for simultaneously profiling of chromatin accessibility and DNA methylation on single molecules. In this study, we combined the principle of NOMe-seq with targeted bisulfite sequencing method to analyze the genome-wide nucleosome occupancy and chromatin accessibility in the promoter and enhancer regions of over 20,000 genes. In addition, we developed CAME, a seed-extension based approach that identifies chromatin accessibility from NOMe-seq. Our results show that our method not only can precisely identify chromatin accessibility but also outperforms other methods.
Project description:DNA methylation and nucleosome positioning work together to generate chromatin structures that regulate gene expression. Nucleosomes are typically mapped using nuclease digestion requiring significant amounts of material and varying enzyme concentrations. We have developed a method (NOMe-seq) that uses a GpC methyltransferase (M.CviPI) and next generation sequencing to generate a high resolution footprint of nucleosome positioning genome-wide using less than 1 million cells while retaining endogenous DNA methylation information from the same DNA strand. Using a novel bioinformatics pipeline we show a striking anti-correlation between nucleosome occupancy and DNA methylation at CTCF regions, that is not present at promoters. We further show that the extent of nucleosome depletion at promoters is directly correlated to expression level and can accommodate multiple nucleosomes and provide genome-wide evidence that expressed non-CpG island promoters are nucleosome depleted. Importantly, NOMe-seq obtains DNA methylation and nucleosome positioning information from the same DNA molecule, giving the first genome-wide DNA methylation and nucleosome positioning correlation at the single molecule and thus, single cell level that can be used to monitor disease progression and response to therapy. Nucleosome Occupancy and Methylome-Sequencing (NOMe-Seq) on IMR90 cell line and 2 GBM cell lines
Project description:We first isolate the PGCs from the Oct4-Gfp knock-in mice, and KIT-positive PGCs from the post-implantation human fetus. Then we use the Nome-seq (Nucleosome Occupancy and Methylome Sequencing), using a in vitro GpC methyltransferase (M.CviPI) and next generation sequencing to generate the endogenous DNA methylation information and chromatin accessibility of the same DNA molecules in these mammalian germ cells.
Project description:Analysis of nucleosome positioning and chromatin state by using CpG methyltransferase M.SssI to methylate nuclei. Unmethylated regions that gain methylation (low to high beta value) are known to be accessible and nucleosome depleted. Method used to study changes after epigenetic drug treatments identified that majority of demethylation events are not accompanied by chromatin accessibility changes. RNA harvested from cells post epigenetic drug treatment, with 5-Aza-CdR or SAHA
Project description:We compare the global DNA methylation and nucleosome occupancy patterns of HCT116 colon cancer cells with its genetic derivatives DKO1 cells which lack DNMT3B and DNMT1 activity Simultaneous genome-wide mapping of DNA methylation and nucleosome occupancy of HCT116 and DKO1 cells using NOMe-seq, rep2
Project description:Analysis of nucleosome positioning and chromatin state by using CpG methyltransferase M.SssI to methylate nuclei. Unmethylated regions that gain methylation (low to high beta value) are known to be accessible and nucleosome depleted. Method used to study changes after epigenetic drug treatments identified that majority of demethylation events are not accompanied by chromatin accessibility changes. Intact nuclei are harvested from cells and treated with M.SssI. DNA is then extracted, bisulfite converted and run on an Infinium methylation array, along with a no-enzyme control. Background subtracted beta values (listed below) are used to determine regions that have gained methylation on enzyme treatment compared to the control - and these are used to infer chromatin state
Project description:Probing epigenetic features on long molecules of DNA has tremendous potential to advance our understanding of the phased epigenome. In this study, we evaluate CpG methylation and chromatin accessibility simultaneously on long strands of DNA using GpC methyltransferase to exogenously label open chromatin, coupled with nanopore sequencing technology. We performed nanopore sequencing of Nucleosome Occupancy and Methylome (nanoNOMe) on four human cell lines (GM12878, MCF-10A, MCF-7, MDA-MB-231), and demonstrate the ability to directly measure methylation and chromatin accessibility in genomic features such as structural variations and repetitive elements. The long single-molecule resolution allows footprinting of protein and nucleosome binding and determining the combinatorial promoter epigenetic state on individual molecules. Long-read sequencing makes it possible to robustly assign reads to haplotypes, enabling allele-specific epigenetic analysis across the genome. We use existing SNV data on GM12878 to present the first fully phased human Probing epigenetic features on long molecules of DNA has tremendous potential to advance our understanding of the phased epigenome. We evaluate CpG methylation and chromatin accessibility simultaneously on long strands of DNA using GpC methyltransferase to exogenously label open chromatin, coupled with nanopore sequencing technology. We performed nanopore sequencing of Nucleosome Occupancy and Methylome (nanoNOMe) on four human cell lines (GM12878, MCF-10A, MCF-7, MDA-MB-231), and demonstrate the ability to directly measure methylation and chromatin accessibility in genomic features such as structural variations and repetitive elements. The long single-molecule resolution allows footprinting of protein and nucleosome binding and determining the combinatorial promoter epigenetic state on individual molecules. Long-read sequencing makes it possible to robustly assign reads to haplotypes, enabling allele-specific epigenetic analysis across the genome. We use existing SNV data on GM12878 to present the first fully phased human epigenome, consisting of chromosome-level allele-specific profiles of CpG methylation and chromatin accessibility.mosome-level allele-specific profiles of CpG methylation and chromatin accessibility.
Project description:DNA methylation and nucleosome positioning work together to generate chromatin structures that regulate gene expression. Nucleosomes are typically mapped using nuclease digestion requiring significant amounts of material and varying enzyme concentrations. We have developed a method (NOMe-seq) that uses a GpC methyltransferase (M.CviPI) and next generation sequencing to generate a high resolution footprint of nucleosome positioning genome-wide using less than 1 million cells while retaining endogenous DNA methylation information from the same DNA strand. Using a novel bioinformatics pipeline we show a striking anti-correlation between nucleosome occupancy and DNA methylation at CTCF regions, that is not present at promoters. We further show that the extent of nucleosome depletion at promoters is directly correlated to expression level and can accommodate multiple nucleosomes and provide genome-wide evidence that expressed non-CpG island promoters are nucleosome depleted. Importantly, NOMe-seq obtains DNA methylation and nucleosome positioning information from the same DNA molecule, giving the first genome-wide DNA methylation and nucleosome positioning correlation at the single molecule and thus, single cell level that can be used to monitor disease progression and response to therapy.
Project description:Analysis of nucleosome positioning and chromatin state by using CpG methyltransferase M.SssI to methylate nuclei. Unmethylated regions that gain methylation (low to high beta value) are known to be accessible and nucleosome depleted. Method used to study changes after epigenetic drug treatments identified that majority of demethylation events are not accompanied by chromatin accessibility changes.
Project description:Analysis of nucleosome positioning and chromatin state by using CpG methyltransferase M.SssI to methylate nuclei. Unmethylated regions that gain methylation (low to high beta value) are known to be accessible and nucleosome depleted. Method used to study changes after epigenetic drug treatments identified that majority of demethylation events are not accompanied by chromatin accessibility changes.