Project description:We performed a meta analysis of publicly available TET1, 5mC, 5hmC and genome wide bisulfite profiling data mostly from mouse embryonic stem cells (ESC). Genome wide chromatin immunoprecipitation combined with deep sequencing (ChIP-seq) has revealed binding of the TET1 protein at CpG-island (CGI) promoters and at bivalent promoters. We show that TET1 also coincides with DNAseI hypersensitive sites (HS). Presence of TET1 at these THREE locations suggests that it may play a dual role: an active role at CpG-islands and DNAseI hypersensitive sites and a repressive role at bivalent loci. In line with the presence of TET1, significant enrichment of 5hmC but not 5mC is detected at bivalent promoters and DNaseI HS. Surprisingly, 5hmC is not detected or present at very low levels at CGI promoters notwithstanding the presence of TET1 at these loci. Our meta analysis suggest that asymmetric methylation is present at CA- and CT-repeats in the genome of some human ESC. Examination of the distribution of 5-methylcytosine and 5-hydroxymethylcytosine in the genome of mouse embryonic stem cells.
Project description:DNA methylation of C5-cytosine (5mC) in the mammalian genome is a key epigenetic event that is critical for various cellular processes. However, how the genome-wide 5mC pattern is dynamically regulated remains a fundamental question in epigenetic biology. The TET family of 5mC hydroxylases, which convert 5mC to 5-hydroxymethylcytosine (5hmC), have provided a new potential mechanism for the dynamic regulation of DNA methylation. The extent to which individual Tet family members contribute to the genome-wide 5mC and 5hmC patterns and associated gene network remains largely unknown. Here we report genome-wide mapping of Tet1 and 5hmC in mESCs and reveal a mechanism of action by which Tet1 controls 5hmC and 5mC levels in mESCs. In combination with microarray and mRNA-seq expression profiling, we identify a comprehensive yet intricate gene network influenced by Tet1. We propose a model whereby Tet1 controls DNA methylation both by binding to CpG-rich regions to prevent unwanted DNA methyltransferase activity, and by converting the existing 5mC to 5hmC through its enzymatic activity. This Tet1-mediated antagonism of CpG methylation imparts differential maintenance of DNA methylation status at Tet1 target loci, thereby providing a new regulatory mechanism for establishing the epigenetic landscape of mESCs, which ultimately contributes to mESC differentiation and the onset of embryonic development. To determine the genome-wide distribution of Tet1 and 5hmC in mouse ES cells, as well as identify the gene transcription changes after Tet1 depletion. GSM706669-GSM706671: We used GST pull-down followed by deep sequencing to map the DNA bound by the Tet1 CXXC domain in vitro. We made two mutants that have a single point mutation (Cys574 to Ala or Cys586 to Ala) in the core CXXC domain to ascertain the essential role of the CXXC domain in DNA binding by comparing the sequencing profile of DNA bound by wild type CXXC with the profiles of the CXXC mutants. GSM706672-GSM706673: Tet1 ChIP-seq was performed to identify the genome-wide distribution of Tet1 in mouse ES cells. GSM706674-GSM706679: We performed hydroxymethylated DNA immunoprecipitation (hMeDIP)-seq combined with a shRNA-mediated gene depletion strategy. To identify the loci specific 5hmC regulation by Tet1, we compared the 5hmC genome-wide distributions in control (Luc shRNA) and Tet1-depleted (Tet1 shRNA2863) mouse ES cells. GSM706680-GSM706682: To identify the gene regulation network by Tet1, we compared the gene expression profiles of control (scramble shRNA) and Tet1-depleted (Tet1 shRNA 2863 and Tet1 shRNA 3387) mouse ES cells determined by mRNA-seq.
Project description:Numerous chromatin regulators are required for embryonic stem (ES) cell self-renewal and pluripotency, but few have been studied in detail. Here, we examine the roles of several chromatin regulators whose loss affects the pluripotent state of ES cells. We find that Mbd3 and Brg1 antagonistically regulate a common set of genes by regulating promoter-proximal nucleosome occupancy and recruitment of RNA polymerase II. Furthermore, both Mbd3 and Brg1 play key roles in the biology of 5-hydroxymethylcytosine (5hmC): Mbd3 colocalizes with both Tet1 and 5hmC in vivo, its localization is Tet1-dependent, and binding of Mbd3/NURD to DNA in vitro is inhibited by methylcytosine, but not hydroxymethylcytosine. Finally, both Mbd3 and Brg1 are themselves required for normal levels of 5hmC in vivo. Together, our results identify an effector for 5hmC, and reveal that control of gene expression by antagonistic chromatin regulators is a surprisingly common regulatory strategy in ES cells. Genomic binding profiles of Mbd3 in normal ES cells, along with ES cells depleted of additional chromatin regulators, Brg1 and Tet1 were performed by ChIP-seq. In addition, we performed mapping of RNA Polymerase II in control (EGFP), Mbd3 and Brg1 knockdown ES cells by ChIP-seq.
Project description:In order to explore the status of DNA methylation in hypoxia response, we show that TET1, a DNA dioxygenase converting 5-methylcytosine (5mC) into 5-hydroxymethylcytosine (5hmC), regulates hypoxia-responsive gene expression. Hypoxia/HIF-2α regulates the expression of TET1. Knockdown of TET1 mitigated hypoxia-induced EMT. RNA sequencing and 5hmC sequencing identified the set of TET1-regulated genes. Four samples (Four samples, Hypoxia (scrambled control), Hypoxia (TET1-si), Normoxia (scrambled control) and Normoxia (TET1-si), are performed by RNA-Seq and hMeDIP-Seq RNA-Seq and hMeDIP-Seq
Project description:In order to explore the status of DNA methylation in hypoxia response, we show that TET1, a DNA dioxygenase converting 5-methylcytosine (5mC) into 5-hydroxymethylcytosine (5hmC), regulates hypoxia-responsive gene expression. Hypoxia/HIF-2α regulates the expression of TET1. Knockdown of TET1 mitigated hypoxia-induced EMT. RNA sequencing and 5hmC sequencing identified the set of TET1-regulated genes. Four samples (Four samples, Hypoxia (scrambled control), Hypoxia (TET1-si), Normoxia (scrambled control) and Normoxia (TET1-si), are performed by RNA-Seq and hMeDIP-Seq
Project description:We report that full length TET1 (TET1-FL) overexpression fails to induce global DNA demethylation in HEK293T cells. The preferential binding of TET1-FL to hypomethylated CpG islands (CGIs) through its CXXC domain leads to its inhibited 5-hydroxymethylcytosine (5hmC) production as methylation level increases. TET1-FL-induced 5hmC accumulates at CGI edges, while TET1 knockdown induces methylation spreading from methylated edges into hypomethylated CGIs. However, TET1 can regulate gene transcription independent of its dioxygenase catalytic function. Thus, our results identify TET1 as a maintenance DNA demethylase that does not purposely decrease methylation levels, but specifically maintains the DNA hypomethylation state of CGIs in adult cells. hMeDIP-seq analysis of genomic 5-hydroxymethylcytosine in HEK293T cells overexpressing mTET1-CD, TET1-CD, mTET1-FL, or TET1-FL
Project description:Precise regulation of DNA methylation in mammals is critical for genome stability and epigenetic regulation. The discovery of the ten-eleven translocation (TET) proteins catalyzing the oxidation from 5-methylcytosine (5mC) to 5-hydroxymethylcytosine (5hmC), 5-formylcytosine (5fC), and 5-carboxylcytosine (5caC) revolutionized the perspective on the complexity and regulation of DNA modifications. Despite accumulating knowledge about the role of TET1, it remains unclear to what extent these can be attributed to its catalytic activity. Here, we use genome engineering and quantitative multi-omics approaches to dissect the role and mechanism of TET1 in mESCs. Our study identifies TET1 as an essential interaction hub for multiple chromatin modifying complexes and as a global regulator of histone modifications. Strikingly, we find that the majority of transcriptional regulation depends on non-catalytic functions of TET1. Moreover, we show that the establishment of H3K9me3 and H4K20me3 at ERV1, ERVK, and ERVL is mediated by TET1 independent of DNA demethylation. We provide evidence that repression of endogenous retroviruses depends on the interaction between TET1 and SIN3A. In summary, we demonstrate that the non-catalytic functions of TET1 are critical for regulation of gene expression and the silencing of endogenous retroviruses in mESCs.
Project description:TET1, the founding member of the TET family of enzymes (TET1/2/3) that convert 5-methylcytosine (5mC) to 5-hydroxymethylcytosine (5hmC), was first identified as a partner gene in MLL-rearranged leukemia, but its definitive pathological role in leukemia is unclear. The down-regulation of all three TET genes and loss-of-function mutations of TET2 have been frequently observed in various cancers, and it was thought that they all play tumor-suppressor roles in tumorigenesis. Here we show that TET1 is likely a direct target of MLL and significantly up-regulated in MLL-rearranged leukemia, associated with an increased level of 5hmC. Our further in vitro and in vivo studies demonstrate that Tet1 plays an indispensable oncogenic role in MLL-rearranged leukemia, through cooperating with MLL fusion proteins in regulating their co-targets including the Hoxa/Meis1/Pbx3/Flt3 genes. Our data delineate a MLL-fusion/Tet1/Hoxa/Meis1/Pbx3/Flt3 signaling axis in MLL-rearranged leukemia, and highlight TET1 as a potential therapeutic target in treating this presently therapy-resistant disease. We report genome-wide 5hmC enrichment profiles and RNA-Seq gene expression in MLL-AF9 transformed and control mouse bone marrow mononuclear cells. These 5hmC profiles are derived from selctive chemical labeling and enrichment of 5hmC containing genomic DNA fragments, while the RNA-Seq expression profiles are generated from polyA enriched RNA