Project description:We analyzed oxidized 5-methylcytosine derivatives 5-hydroxymethylcytosine, 5-formylcytosine and 5-carboxylcytosine in nucleic acids of multicellular fungi Laccaria bicolor and Coprinopsis cinerea which have been used as models to study DNA methylation, developmental processes and symbiotic interactions. All three cytosine derivatives were detected in the genomes of both fungi, and importantly, we discovered 5carC in the RNA fractions, potentially including large non-coding, messenger RNAs and small RNA molecules, indicating gene regulatory functions of 5carC.
Project description:Although various methods have been developed for sequencing cytosine epigenetic modifications, specific and quantitative sequencing of the two major epigenetic modifications of cytosines, 5-methylcytosine (5mC) and 5-hydroxymethylcytosine (5hmC) at base-resolution is still challenging. Most times it requires subtraction of two methods to obtain both the true 5mC and 5hmC information, which increases noise and requires high sequencing depth. Recently we developed TET assisted pyridine borane sequencing (TAPS) for bisulfite-free direct sequencing of DNA methylation, which provides the sum of 5mC and 5hmC. Here we extend it to two sister methods, TAPSβ and CAPS (Chemical-Assisted Pyridine borane Sequencing), for whole-genome subtraction-free and specific sequencing of 5mC and 5hmC, respectively. We also demonstrated Pyridine borane Sequencing (PS) of whole-genome 5-formylcytosine (5fC), and 5-carboxylcytosine (5caC), the further oxidized derivatives of 5mC and 5hmC. This completes the versatile borane reduction chemistry-based methods as a comprehensive suite for direct and quantitative sequencing of all four individual cytosine epigenetic modifications.
Project description:Enzymatic oxidation of 5-methylcytosine (5mC) in DNA by the Tet (Ten-eleven translocation) family of dioxygenases reprograms genome function during pre-implantation development and in primordial germ cells. Tet-oxidized derivatives of 5mC such as 5-hydroxymethylcytosine (5hmC) act as transient intermediates in DNA demethylation or serve as stable epigenetic marks, yet how these alternate fates are specified at individual CpGs is not understood. Here, we report that the Sos-response associated peptidase (SRAP) domain-containing protein Srap1, the mammalian orthologue of an ancient protein superfamily operonically associated with the DNA damage response in bacteria and bacteriophage, binds directly and selectively to Tet-oxidized forms of 5mC in DNA and catalyses turnover of these bases to unmodified cytosine by an autopeptidase cleavage-coupled endonuclease. Biallelic inactivation of Srap1 in mouse embryonic stem (ES) cells results in the global accumulation of Tet-oxidized 5mC derivatives, with ectopic 5hmC in promoters of highly expressed genes, across gene bodies and within enhancer elements. Srap1 deficiency causes partially penetrant lethality in late blastocysts prior to uterine implantation, while surviving midgestation embryos exhibit aberrant patterns of DNA methylation associated with altered gene expression, including hypermethylation in regions closely linked to ectopic 5hmC detected earlier in development. Thus, highly specific removal of 5hmC and its oxidized derivatives by Srap1 sustains genome-wide DNA methylation homeostasis. These findings establish a function for a previously unknown structural class of DNA base modification-specific eraser enzymes that combine the catalytic properties of an autopeptidase with endonuclease activation, and position Srap1 as a key determinant of 5mC demethylation trajectories during mammalian embryonic development.
Project description:We performed 5hmC/5mC DNA Immunoprecipitation followed high-throughput sequencing using the cell sample along the whole TSKM secondary reprogramming system. The TSKM 0D is the fibroblasts deried from TSKM-iPS mouse as the starting cells of the reprogramming.The intermediate cells is 3-days induced cells which are refered as TSKM 3D cells, and the final reprogrammed cells is the iPS cells with full pluripotency driven from this secondary system. We compared the profiling of 5-hydroxymethylcytosine and 5-methylcytosine modifications in these different cell lines. We found that: a widespread accompanying increase of 5hmC and 5mC at TSS and ES-active regulation regions followed by 5mC-5hmC pattern switch. Taking the advantage of the newly established TSKM secondary reprogramming system, the epigenetic remodeling and regulation mechanisms can be further investigated to advance our understanding of the epigenetic barriers and decipher the dynamic mechanism in somatic cell reprogramming. Examination of 5-hydroxymethylcytosine/5-methylcytosine modifications in a Tet1-mediated secondary reprogramming system
Project description:5-hydroxymethylcytosine (5hmC), an oxidized derivative of 5-methylcytosine (5mC), has been implicated as an important epigenetic regulator of mammalian development. Current procedures use cost-prohibitive DNA sequencing methods to discriminate 5hmC from 5mC, limiting their accessibility to the scientific community. Here we report a method that combines TET-assisted bisulfite conversion with Illumina 450K DNA methylation arrays for a low-cost high-throughput approach that distinguishes 5hmC and 5mC signals. Implementing this approach, termed TAB-array, we assessed DNA methylation dynamics in the differentiation of human pluripotent stem cells into cardiovascular and neural progenitors. With the ability to discriminate 5mC and 5hmC, we found a much larger number of dynamically methylated genomic regions implicated in the development of these lineages than we could detect by 5mC analysis alone. The increased resolution and accuracy afforded by this approach provides a powerful means to investigate the distinct contributions of 5mC and 5hmC in human development and disease. We generated illumina 450k DNA methylation data for a total of 9 sample groups with two biological replicates for each group. Data for 4/9 groups were generated from glucosylated and bisulfite converted DNA, from human induced plurupotent stem cells (hIPSCs), differentiated cardiovascular progenitors (CVPs), differentiated neural progenitors (NPCs), and fibroblasts. Data for the next 4/9 groups were generated from glucosylated, TET-oxidized and bisulfite converted DNA, from and included replicates of hIPSCs, CVPs, NPCs, and fibroblasts. Data for the last group was generated from standard bisulfite converted DNA (not glucosylated) from fibroblasts.
Project description:Oxidative modification of 5-methylcytosine (5mC) by TET DNA dioxygenases generates 5-hydroxymethylcytosine (5hmC), the most abundant form of oxidized 5mC. Existing single-cell bisulfite sequencing methods cannot resolve 5mC and 5hmC, leaving the cell-type-specific regulatory mechanisms of TET and 5hmC largely unknown. Here we present Joint single-nucleus (hydroxy)methylcytosine sequencing (Joint-snhmC-seq), a scalable and quantitative approach that simultaneously profiles 5hmC and true 5mC in single cells by harnessing differential deaminase activity of APOBEC3A towards 5mC and chemically protected 5hmC. Joint-snhmC-seq profiling of single nuclei from the mouse brains reveals an unprecedented level of epigenetic heterogeneity of both 5hmC and true 5mC at single-cell resolution. We show that cell-type-specific profiles of 5hmC or true 5mC improve multi-modal single-cell data integration, enable accurate identification of neuronal subtypes, and uncover context-specific regulatory effects of cell-type-specific genes by TET enzymes.
Project description:Oxidative modification of 5-methylcytosine (5mC) by TET DNA dioxygenases generates 5-hydroxymethylcytosine (5hmC), the most abundant form of oxidized 5mC. Existing single-cell bisulfite sequencing methods cannot resolve 5mC and 5hmC, leaving the cell-type-specific regulatory mechanisms of TET and 5hmC largely unknown. Here we present Joint single-nucleus (hydroxy)methylcytosine sequencing (Joint-snhmC-seq), a scalable and quantitative approach that simultaneously profiles 5hmC and true 5mC in single cells by harnessing differential deaminase activity of APOBEC3A towards 5mC and chemically protected 5hmC. Joint-snhmC-seq profiling of single nuclei from the mouse brains reveals an unprecedented level of epigenetic heterogeneity of both 5hmC and true 5mC at single-cell resolution. We show that cell-type-specific profiles of 5hmC or true 5mC improve multi-modal single-cell data integration, enable accurate identification of neuronal subtypes, and uncover context-specific regulatory effects of cell-type-specific genes by TET enzymes.
Project description:Oxidative modification of 5-methylcytosine (5mC) by TET DNA dioxygenases generates 5-hydroxymethylcytosine (5hmC), the most abundant form of oxidized 5mC. Existing single-cell bisulfite sequencing methods cannot resolve 5mC and 5hmC, leaving the cell-type-specific regulatory mechanisms of TET and 5hmC largely unknown. Here we present Joint single-nucleus (hydroxy)methylcytosine sequencing (Joint-snhmC-seq), a scalable and quantitative approach that simultaneously profiles 5hmC and true 5mC in single cells by harnessing differential deaminase activity of APOBEC3A towards 5mC and chemically protected 5hmC. Joint-snhmC-seq profiling of single nuclei from the mouse brains reveals an unprecedented level of epigenetic heterogeneity of both 5hmC and true 5mC at single-cell resolution. We show that cell-type-specific profiles of 5hmC or true 5mC improve multi-modal single-cell data integration, enable accurate identification of neuronal subtypes, and uncover context-specific regulatory effects of cell-type-specific genes by TET enzymes.
Project description:Oxidative modification of 5-methylcytosine (5mC) by TET DNA dioxygenases generates 5-hydroxymethylcytosine (5hmC), the most abundant form of oxidized 5mC. Existing single-cell bisulfite sequencing methods cannot resolve 5mC and 5hmC, leaving the cell-type-specific regulatory mechanisms of TET and 5hmC largely unknown. Here we present Joint single-nucleus (hydroxy)methylcytosine sequencing (Joint-snhmC-seq), a scalable and quantitative approach that simultaneously profiles 5hmC and true 5mC in single cells by harnessing differential deaminase activity of APOBEC3A towards 5mC and chemically protected 5hmC. Joint-snhmC-seq profiling of single nuclei from the mouse brains reveals an unprecedented level of epigenetic heterogeneity of both 5hmC and true 5mC at single-cell resolution. We show that cell-type-specific profiles of 5hmC or true 5mC improve multi-modal single-cell data integration, enable accurate identification of neuronal subtypes, and uncover context-specific regulatory effects of cell-type-specific genes by TET enzymes.