Project description:We present Nanopore-DamID, a method to simultaneously detect cytosine methylation and DNA-protein interactions from single molecules, via selective sequencing of adenine-labelled DNA. Assaying LaminB1 and CTCF binding with Nanopore-DamID, we identify escape from LAD-associated repression of hypomethylated promoters amidst generalised hypermethylation of LaminB1-associated regulatory elements. We detect novel CTCF binding sites in highly repetitive regions, and allele-specific CTCF binding to imprinted genes and the active X chromosome. Nanopore-DamID highlights the importance of DNA methylation to transcription factor activity.
Project description:Active regulatory elements in eukaryotes are typically characterized by an open, nucleosome-depleted chromatin structure; mapping areas of open chromatin has accordingly emerged as a widely used tool in the arsenal of modern functional genomics. However, existing approaches for profiling chromatin accessibility are limited by their reliance on DNA fragmentation and short read sequencing, which leaves them unable to provide information about the state of chromatin on larger scales or reveal coordination between the chromatin state of individual distal regulatory elements. To address these limitations, we have developed a method for profiling accessibility of individual chromatin fibers at multi-kilobase length scale (SMAC-seq, or Single-Molecule long-read Acessible Chromatin mapping sequencing assay), enabling the simultaneous, high-resolution, single-molecule assessment of the chromatin state of distal genomic elements. Our strategy is based on combining the preferential methylation of open chromatin regions by DNA methyltransferases (CpG and GpC 5-methylcytosine (5mC) and N6-methyladenosine (m6A) enzymes) and the ability of long-read single-molecule nanopore sequencing to directly read out the methylation state of individual DNA bases. Applying SMAC-seq to the budding yeast Saccharomyces cerevisiae, we demonstrate that aggregate SMAC-seq signals match bulk-level accessibility measurements, observe single-molecule protection footprints of nucleosomes and transcription factors, and quantify the correlation between the chromatin states of distal genomic elements
2019-12-01 | GSE128290 | GEO
Project description:Simultaneous profiling of histone modifications and DNA methylation via nanopore sequencing
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:DamID is a powerful technique for identifying regions of the genome bound by a DNA-binding (or DNA-associated) protein. Currently no method exists for automatically processing next-generation sequencing DamID (DamID-seq) data, and the use of DamID-seq datasets with normalisation based on read-counts alone can lead to high background and the loss of bound signal. DamID-seq thus presents novel challenges in terms of normalisation and background minimisation. We describe here damidseq_pipeline, a software pipeline that performs automatic normalisation and background reduction on multiple DamID-seq FASTQ or BAM datasets. Single replicate profiling of pol II occupancy in 3rd instar larval neuroblasts of Drosophila
Project description:Genome regulation depends on carefully programmed protein-DNA interactions that maintain or alter gene expression states, often by influencing chromatin organization. Most studies of these interactions to date have relied on bulk methods, which in many systems cannot capture the dynamic single-cell nature of these interactions as they modulate cell states. One method allowing for sensitive single-cell mapping of protein-DNA interactions is DNA adenine methyltransferase identification (DamID), which records a protein’s DNA-binding history by methylating adenine bases in its vicinity, then selectively amplifies and sequences these methylated regions. These interaction sites can also be visualized using fluorescent proteins that bind to methyladenines. Here we combine these imaging and sequencing technologies in an integrated microfluidic platform (µDamID) that enables single-cell isolation, imaging, and sorting, followed by DamID. We apply this system to generate paired single-cell imaging and sequencing data from a human cell line, in which we map and validate interactions between DNA and nuclear lamina proteins, providing a measure of 3D chromatin organization and broad gene regulation patterns. µDamID provides the unique ability to compare paired imaging and sequencing data for each cell and between cells, enabling the joint analysis of the nuclear localization, sequence identity, and variability of protein-DNA interactions.
Project description:Here we present a new version of the DamID method that allows efficient capturing of protein-DNA interactions and mRNA output from the same single cell. With this protocol, we have measured the direct impact of spatial genome positioning and chromatin accessibility on mRNA output in human haploid cells
Project description:Identity and plasticity of CD4 T helper (Th) cells are regulated in part by epigenetic mechanisms. Cytosine methylation in CpG context (5mCpG) and cytosine hydroxymethylation (5hmCpG) are DNA modifications that identify stable cell phenotypes. To assess transition states in Th cells, we developed a method based on Cas9-targeted single molecule nanopore sequencing and found that 5mCpG can be used as markers of cellular identity. Targeting as few as 10 mouse selected genomic loci, we were able to distinguish major differentiated T cell subtypes as well as intermediate phenotypes by their native DNA 5mCpG patterns. Moreover, by using off-target sequences we were able to infer transcription factor activities relevant to each cell subtype. Our data highlight the potential to exploit native DNA methylation profiling to study physiological and pathological Th transition states.