Project description:Cisplatin, one of the most widely used anticancer drugs, crosslinks DNA and ultimately induces cell death. However, the genomic pattern of cisplatin-DNA adducts remains unknown, due to the lack of a reliable and sensitive genome-wide method. Here we present “cisplatin-seq” to identify genome-wide cisplatin crosslinking sites at base-resolution. Cisplatin-seq reveals that mitochondrial DNA is a preferred target of cisplatin. For nuclear genome, cisplatin-DNA adducts are enriched within promoters and regions harboring transcription termination sites. While the density of GG dinucleotide determines the initial crosslinking of cisplatin, binding of proteins to the genome largely contributes to the accumulative pattern of cisplatin-DNA adducts.
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:Platinum chemotherapies induce damages in DNA that distort the helical structure. In human cells, these adducts are removed primarily by the Nucleotide Excision Repair pathway. In this study, we mapped both cisplatin and oxaliplatin induced damages and their repair at single nucleotide resolution across the human genome.
Project description:We report RBS-Seq, a new RNA bisulfite sequencing method enabling the sensitive and simultaneous detection of m5C, pseudouridine, and m1A at single-base resolution transcriptome-wide. For each, we detect ‘signature’ base mismatches (for m5C and m1A), or 1-2 base deletions (for pseudouridine) structurally explained by ribose ring-opened pseudouridine-mono-bisulfite adducts. Our profiles for pseudouridine reveal clear signatures at known sites in tRNAs and rRNAs, and provide hundreds of new targets in non-coding RNAs and mRNAs. However, our results diverge greatly from prior work, suggesting ~10-fold fewer m5C sites, and the absence of substantial m1A in mRNAs.
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: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.
Project description:Deoxyuridine (dU) in DNA can result from deamination of cytosine and dUMP misincorporation. The easy single-nucleotide resolution assay for dU are crucial to understanding its role in genome. Herein, we present a new concept of “base substitution” for accurate single-nucleotide resolution profiling of dU. The method termed AI-Seq (Artificial Incorporation of a modified nucleobase for sequencing) was developed using artificial cytosine (N3-C) to replace dU. After the artificial base construction, dU can read as cytosine during polymerase chain reaction assay. AI-seq was validated on synthetic DNA and then applied to the genome of HEK293T cell line. Collectively, the “base substitution” provides a novel approach for generating comprehensive information about the distribution of dU and can be potentially adapted to detect other epigenetic modifications.