Project description:The detection of low-abundance DNA N6-methyladenine (DNA-m6A) remains challenging, limiting our understanding of this novel base in eukaryotes. To address this, we introduce an approach for systematically validating the selectivity and sensitivity of antibody-based DNA-m6A methods, revealing most commercial antibodies as poorly selective towards DNA-m6A. Finally, we validate selective anti-DNA-m6A antibodies with sensitivity <2 ppm, and expose distinct pathways mediating endogenous DNA-m6A in C. reinhardtii, A. thaliana, and D. melanogaster.
Project description:In mammalian cells, DNA methylation on the 5th position of cytosine (5mC) plays an important role as an epigenetic mark. However, DNA methylation was considered to be absent in C. elegans because of the lack of detectable 5mC as well as homologs of the cytosine DNA methyltransferases. Here, using multiple approaches, we demonstrate the presence of adenine N6-methylation (6mA) in C. elegans DNA. We further demonstrate that this modification increases trans-generationally in a paradigm of epigenetic inheritance. Importantly, we identify a DNA demethylase, NMAD-1, and a potential DNA methyltransferase, DAMT-1, which regulate 6mA levels and crosstalk between methylation of histone H3K4me2 and 6mA, and control the epigenetic inheritance of phenotypes associated with the loss of the H3K4me2 demethylase spr-5. Together, these data identify a novel DNA modification in C. elegans and raise the exciting possibility that 6mA may be a carrier of heritable epigenetic information in eukaryotes. SMRT-sequencing for a mixed cell population of wildtype worms 6mA ChIP-Seq for a mixed cell population of wildtype worms
Project description:DNA methylation is a key mechanism for regulation of DNA repair, DNA replication, and gene expression. In bacteria, DNA is modified by methylation on C5-cytosine (5mC), N6-adenine (6mA) and N4-cytosine (4mC). Metazoans were thought to only use 5mC to regulate gene expression until the recent discovery of N6-adenine methylation in DNA of diverse metazoan species, including mammals. Here we show by dot blot, immunoprecipitation with 4mC-specific antibodies, and ultra-high performance liquid chromatography coupled with triple-quadrupole mass spectrometry that 4mC also occurs in most eukaryotes. We further characterize 4mC sites on a near genome-wide scale by single molecule real time (SMRT) sequencing in the nematode C. elegans. In C. elegans, 4mC is found in all chromosomes but is relatively sparse on the X chromosome. 4mC is relatively enriched on introns, depleted on exons, and co-localizes with 6mA. In human cells, 4mC is anti-correlated with 5mC. Moreover, 4mC modifications are associated with increased gene expression. Transfection of human cells with a 4mC-modified luciferase reporter plasmid increases luciferase expression as compared to the unmethylated plasmid. These data suggest that 4mC promotes gene transcription, playing an opposing role to 5mC, which generally represses transcription. Thus 4mC modification of DNA is a previously unrecognized mechanism of gene regulation in eukaryotes, providing evidence for a complex epigenetic DNA code.
Project description:DNA methylation on N6-adenine (6mA) has recently been found as a potentially new epigenetic mark in several unicellular and multicellular eukaryotes. However, its distribution patterns and potential functions in land plants, which are primary producers for most ecosystems, remain completely unknown. Here we report global profiling of 6mA sites at single-nucleotide resolution in the genome of Arabidopsis thaliana using single-molecule real-time sequencing. 6mA sites are widely distributed across the Arabidopsis genome and enriched over the pericentromeric heterochromatin regions. Nearly 30% of 6mA sites are present in gene bodies. Further analysis of 6mA methylome and RNA-sequencing data demonstrates that 6mA frequency positively correlates with the gene expression level in Arabidopsis. Consistently, histone variants associated with actively expressed genes interact with 6mA DNA. Our results uncover 6mA as a DNA mark associated with actively expressed genes in Arabidopsis, suggesting that 6mA serves as a novel epigenetic mark in land plants.
Project description:In mammalian cells, DNA methylation on the 5th position of cytosine (5mC) plays an important role as an epigenetic mark. However, DNA methylation was considered to be absent in C. elegans because of the lack of detectable 5mC as well as homologs of the cytosine DNA methyltransferases. Here, using multiple approaches, we demonstrate the presence of adenine N6-methylation (6mA) in C. elegans DNA. We further demonstrate that this modification increases trans-generationally in a paradigm of epigenetic inheritance. Importantly, we identify a DNA demethylase, NMAD-1, and a potential DNA methyltransferase, DAMT-1, which regulate 6mA levels and crosstalk between methylation of histone H3K4me2 and 6mA, and control the epigenetic inheritance of phenotypes associated with the loss of the H3K4me2 demethylase spr-5. Together, these data identify a novel DNA modification in C. elegans and raise the exciting possibility that 6mA may be a carrier of heritable epigenetic information in eukaryotes.
Project description:DNA methylation on N6-adenine (6mA), the most prevalent DNA modification in prokaryotes, has recently been found as a potentially new epigenetic mark in several unicellular and multicellular eukaryotes. However, the distribution patterns and potential functions of 6mA in land plants, which are primary producers for most ecosystems, remain completely unknown. Here we report global profiling of 6mA sites at single-nucleotide resolution in the genomes of Arabidopsis thaliana Columbia-0 (Col), using single-molecule real-time sequencing. DNA methylome analysis shows that 6mA sites are widely distributed across the Col genomes and enriched over the pericentromeric heterochromatin regions. Nearly 30% of 6mA sites are present in gene bodies with a trend of enrichment around the transcriptional start site. In addition to a common consensus 6mA site found in other eukaryotes, novel 6mA sites were found, indicating that 6mA could evolve new functions in land plants. Further analysis of 6mA methylome and RNA-sequencing data demonstrates that 6mA positively correlates with the gene expression level in Col plants. Consistently, DNA affinity chromatography coupled with mass spectrometry reveals that histone variants associated with actively expressed genes interact with 6mA DNA. Our results uncover 6mA as a DNA mark associated with actively expressed genes in Arabidopsis, indicating that 6mA could serve as a potentially novel epigenetic mark in land plants.
Project description:DNA methylation on N6-adenine (6mA), the most prevalent DNA modification in prokaryotes, has recently been found as a potentially new epigenetic mark in several unicellular and multicellular eukaryotes. However, the distribution patterns and potential functions of 6mA in land plants, which are primary producers for most ecosystems, remain completely unknown. Here we report global profiling of 6mA sites at single-nucleotide resolution in the genomes of Arabidopsis thaliana Columbia-0 (Col), using single-molecule real-time sequencing. DNA methylome analysis shows that 6mA sites are widely distributed across the Col genomes and enriched over the pericentromeric heterochromatin regions. Nearly 30% of 6mA sites are present in gene bodies with a trend of enrichment around the transcriptional start site. In addition to a common consensus 6mA site found in other eukaryotes, novel 6mA sites were found, indicating that 6mA could evolve new functions in land plants. Further analysis of 6mA methylome and RNA-sequencing data demonstrates that 6mA positively correlates with the gene expression level in Col plants. Consistently, DNA affinity chromatography coupled with mass spectrometry reveals that histone variants associated with actively expressed genes interact with 6mA DNA. Our results uncover 6mA as a DNA mark associated with actively expressed genes in Arabidopsis, indicating that 6mA could serve as a potentially novel epigenetic mark in land plants.
Project description:DNA methylation on N6-adenine (6mA) has recently been found as a potentially new epigenetic mark in several unicellular and multicellular eukaryotes. However, its distribution patterns and potential functions in land plants, which are primary producers for most ecosystems, remain completely unknown. Here we report global profiling of 6mA sites at single-nucleotide resolution in the genome of Arabidopsis thaliana using single-molecule real-time sequencing. 6mA sites are widely distributed across the Arabidopsis genome and enriched over the pericentromeric heterochromatin regions. Nearly 30% of 6mA sites are present in gene bodies. Further analysis of 6mA methylome and RNA-sequencing data demonstrates that 6mA frequency positively correlates with the gene expression level in Arabidopsis. Consistently, histone variants associated with actively expressed genes interact with 6mA DNA. Our results uncover 6mA as a DNA mark associated with actively expressed genes in Arabidopsis, suggesting that 6mA serves as a novel epigenetic mark in land plants.