Project description:The study of 5-hydroxylmethylcytosines (5hmC), the sixth base of the mammalian genome, as an epigenetic mark has been hampered by a lack of method to map it at single-base resolution. Previous affinity purification-based methods could not precisely locate 5hmC nor accurately determine its relative abundance at each modified site. We here present a genome-wide approach for mapping 5hmC at base resolution. Application of this new method to the embryonic stem cells not only confirms widespread distribution of 5hmC in mammalian genome, but also reveals a strong sequence bias and strand asymmetry at sites of 5hmC. Additionally, the relative abundance of 5hmC varies significantly depending on the types of functional sequences, suggesting different mechanisms for 5hmC deposition and maintenance. Furthermore, we observe high levels of 5hmC and reciprocally low levels of 5mC at transcription factor binding sites, revealing a dynamic DNA methylation process at cis-regulatory elements. Base resolution sequencing of 5 hydroxymethylcytosine in human and mouse embryonic stem cells
Project description:The study of 5-hydroxylmethylcytosines (5hmC), the sixth base of the mammalian genome, as an epigenetic mark has been hampered by a lack of method to map it at single-base resolution. Previous affinity purification-based methods could not precisely locate 5hmC nor accurately determine its relative abundance at each modified site. We here present a genome-wide approach for mapping 5hmC at base resolution. Application of this new method to the embryonic stem cells not only confirms widespread distribution of 5hmC in mammalian genome, but also reveals a strong sequence bias and strand asymmetry at sites of 5hmC. Additionally, the relative abundance of 5hmC varies significantly depending on the types of functional sequences, suggesting different mechanisms for 5hmC deposition and maintenance. Furthermore, we observe high levels of 5hmC and reciprocally low levels of 5mC at transcription factor binding sites, revealing a dynamic DNA methylation process at cis-regulatory elements.
Project description:Mapping genome-wide 5-hydroxymethylcytosine (5hmC) and 5-formylcytosine (5fC) at single-base resolution is important to understand their biological functions. We present a cost-efficient mapping method that combines 5hmC-specific restriction enzyme PvuRts1I with a 5hmC enrichment method. The sensitive method enables detection of low abundant 5hmC sites, providing a more complete 5hmC landscape than available bisulfite-based methods. This method generated the first genome-wide 5fC map at single-base resolution. Parallel analyses revealed that 5hmC and 5fC existed with lower abundance and more dynamically in non-CpG context than in CpG context. In the genic region, distribution of 5hmCpG and 5fCpG differed from 5hmCH and 5fCH (H=A, T, C). 5hmC and 5fC were distributed distinctly at regulatory protein-DNA binding sites, depleted in permissive transcription factor binding sites, and enriched at active and poised enhancers. This sensitive bisulfite-conversion free method can be applied to biological samples with limited starting material or low abundance of cytosine modifications. Sensitive mapping of genome-wide 5-hydroxymethylcytosine and 5-formylcytosine in mouse embryonic stem cell at single-base resolution by combining 5-hydroxymethylcytosine specific restriction enzyme PvuRts1I and 5-hydroxymethylcytosine enrichment method (selective chemical labeling or SEAL)
Project description:High-resolution detection of genome-wide 5-hydroxymethylcytosine (5hmC) sites of small-scale samples represents a continuous challenge. Here, we present CATCH-seq, a bisulfite-free, base-resolution method for the genome-wide detection of 5hmC. CATCH-seq is based on selective 5hmC oxidation, labeling and subsequent C-to-T transition during PCR. Applications of CATCH-seq to nano-scale DNA samples reveal previously underappreciated non-CG 5hmCs in the hESC genome and base-resolution hydroxymethylome in human cell-free DNA.
Project description:To investigate the genomic levels of 5-hydroxymethylcytosine at single-base resolution. The current study developed a method which allows one to study hydroxymethylation of cytosines in the genome via a subtractive method of RRBS and oxidative RRBS.
Project description:Active DNA demethylation in mammals involves TET-mediated oxidation of 5-methylcytosine (5mC) to 5-hydroxymethylcytosine (5hmC), 5-formylcytosine (5fC) and 5-carboxycytosine (5caC). However, genome-wide detection of 5fC at single-base resolution remains challenging. Here we present a bisulfite-free method for the whole-genome analysis of 5fC, based on a selective chemical labeling of 5fC and subsequent C-to-T transition during PCR. Base-resolution 5fC maps reveal limited overlap with 5hmC, with 5fC-marked regions more active than 5hmC-marked ones. Utilization of cyclization-enabled C-to-T transition of 5fC (hence “fC-CET”) to obtain genome-wide map of 5fC at single-base resolution WT and TdgKO mES cell lines. Two non-enriched input DNAs (Input: preAI), two AI labeled samples (Input: AI), two pull-down output samples.
Project description:Cytosine base modifications 5-methylcytosine (5mC), 5-hydroxymethylcytosine (5hmC) and 5-formylcytosine (5fC) are present in mammalian DNA. Here, reduced bisulfite sequencing is developed for quantitatively sequencing 5fC at single-base resolution. This method is then applied with oxidative bisulfite sequencing to gain a map of 5mC, 5hmC and 5fC in mouse embryonic stem cells.
Project description:Cytosine base modifications 5-methylcytosine (5mC), 5-hydroxymethylcytosine (5hmC) and 5-formylcytosine (5fC) are present in mammalian DNA. Here, reduced bisulfite sequencing is developed for quantitatively sequencing 5fC at single-base resolution. This method is then applied with oxidative bisulfite sequencing to gain a map of 5mC, 5hmC and 5fC in mouse embryonic stem cells. 12 samples, reduced representation bisulphite treatment: 4 replicates each for bisulphite (BS), oxidative BS (oxBS) and reduced BS (redBS) for the detection of 5mC, 5hmC and 5fC. Mouse (strain B6C) embryonic stem cells.