Project description:TET proteins convert 5-methylcytosine to 5-hydroxymethylcytosine, an emerging dynamic epigenetic state of DNA that can influence transcription. Evidence has linked TET1 function to epigenetic repression complexes, yet mechanistic information, especially for the TET2 and TET3 proteins, remains limited. Here, we show a direct interaction of TET2 and TET3 with O-GlcNAc transferase (OGT). OGT does not appear to influence hmC activity, rather TET2 and TET3 promote OGT activity. TET2/3-OGT co-localize on chromatin at active promoters enriched for H3K4me3 and reduction of either TET2/3 or OGT activity results in a direct decrease in H3K4me3 and concomitant decreased transcription. Further, we show that Host Cell Factor 1 (HCF1), a component of the H3K4 methyltransferase SET1/COMPASS complex, is a specific GlcNAcylation target of TET2/3-OGT, and modification of HCF1 is important for the integrity of SET1/COMPASS. Additionally, we find both TET proteins and OGT activity promote binding of the SET1/COMPASS H3K4 methyltransferase, SETD1A, to chromatin. Finally, studies in Tet2 knockout mouse bone marrow tissue extend and support the data as decreases are observed of global GlcNAcylation and also of H3K4me3, notably at several key regulators of haematopoiesis. Together, our results unveil a step-wise model, involving TET-OGT interactions, promotion of GlcNAcylation, and influence on H3K4me3 via SET1/COMPASS, highlighting a novel means by which TETs may induce transcriptional activation. ChIP-Seq experiments were performed on Illumina HiScanSQ sequencer in wild-type HEK293T cells for H3K4me3 histone marks, O-GlcNAc and HCF1, for HT-TET2, HT-TET3 and HT-OGT in HEK293T cells overexpressing those three fusion proteins and in TET2 Kd HEK293T cells for H3K4me3 histone marks. ChIP-Seqs were also performed in mouse bone marrow tissues for H3K4me3 histone marks, O-GlcNAc, endogenous Tet2 and in Tet2 Ko bone marrow tissues for H3K4me3 histone marks.
Project description:The TET proteins TET1, TET2 and TET3 constitute a new family of dioxygenases that utilize molecular oxygen and the cofactors Fe(II) and 2-oxoglutarate to convert 5-methylcytosine (5mC) to 5-hydroxy-methylcytosine (5hmC) and further oxidation products in DNA1-5. Here we show that Tet1 and Tet2 have distinct roles in regulating 5hmC deposition and gene expression in mouse embryonic stem cells (mESC). Tet1 depletion in mESC primarily diminishes 5hmC levels at transcription start sites (TSS), whereas Tet2 depletion is mostly associated with decreased 5hmC in gene bodies relative to TSS. 5hmC is enriched at exon start and end sites, especially in exons that are highly expressed, and is significantly decreased upon Tet2 knockdown at the boundaries of high-expressed exons that are selectively regulated by Tet2. In differentiating murine B cells, Tet2 deficiency is associated with selective exon exclusion in the gene encoding the transmembrane phosphatase CD45. Tet2 depletion is associated with increased 5hmC and decreased 5mC at promoters/ TSS regions, possibly because of the redundant activity of Tet1. Together, these data indicate a complex interplay between Tet1 and Tet2 in mESC, and show that loss-of-function of a single TET protein does not necessarily lead to loss of 5hmC and a corresponding gain of 5mC, as generally assumed. The relation between Tet2 loss-of-function and selective changes in exon expression could potentially explain the frequent occurrence of both TET2 loss-of-function mutations and mutations in proteins involved in pre-mRNA splicing in myeloid malignancies in humans. Gene and exon expression analysis in mESC, Tet1 knockdown mESC, and Tet2 knockdown mESC by RNA-sequencing. Mapping of 5-hydroxymethylcytosine in mESC, Tet1 knockdown mESC, and Tet2 knockdown mESC by anti-CMS-seq. Mapping of methylcytosine in mESC, and Tet2 kd mESC by MeDIP-seq.
Project description:Enhancers are fundamental to gene regulation. Post-translational modifications by the small ubiquitin-like modifiers (SUMO) modify chromatin regulation enzymes, including histone acetylases and deacetylases. However, it remains unclear whether SUMOylation regulates enhancer marks, acetylation at the 27th lysine residue of the histone H3 protein (H3K27Ac). We hypothesize that SUMOylation regulates H3K27Ac. To test this hypothesis, we performed genome-wide ChIP-seq analyses. We discovered that knockdown (KD) of the SUMO activating enzyme catalytic subunit UBA2 reduced H3K27Ac at most enhancers. Bioinformatic analysis revealed that TFAP2C-binding sites are enriched in enhancers whose H3K27Ac was reduced by UBA2 KD. ChIP-seq analysis in combination with molecular biological methods showed that TFAP2C binding to enhancers increased upon UBA2 KD or inhibition of SUMOylation by a small molecule SUMOylation inhibitor. However, this is not due to the SUMOylation of TFAP2C itself. Proteomics analysis of TFAP2C interactome on the chromatin identified histone deacetylation (HDAC) machinery. TFAP2C KD reduced HDAC binding to chromatin and increased H3K27Ac marks at enhancer regions, suggesting that TFAP2C is involved in recruiting HDAC. Taken together, our findings provide important insights into regulation of enhancer marks by SUMOylation.
Project description:TET2 directly interacts with OGT, which is important for the chromatin association of OGT in vivo. Although this specific interaction does not regulate the enzymatic activity of TET2, it facilitates OGT-dependent histone O-GlcNAcylation. Moreover, OGT associates with TET2 at transcription starting sites (TSS). Down-regulation of TET2 reduces the amount of H2B S112 GlcNAc marks in vivo, which are associated with gene transcription regulation. We used microarray to test the function of TET2 on gene expression. Mouse ES cells infected with control knockdown(KD) or TET2 KD virus were treated with puromycin. ES cells were extracted for RNA and hybridization on Affymetrix microarrays.
Project description:TET2 directly interacts with OGT, which is important for the chromatin association of OGT in vivo. Although this specific interaction does not regulate the enzymatic activity of TET2, it facilitates OGT-dependent histone O-GlcNAcylation. Moreover, OGT associates with TET2 at transcription starting sites (TSS). Down-regulation of TET2 reduces the amount of H2B S112 GlcNAc marks in vivo, which are associated with gene transcription regulation. We found that OGT interacts with TET2 tightly. Using ChIP-seq with specific antibodies, we tested the co-localization of TET2 and OGT in genome level.
Project description:The TET proteins TET1, TET2 and TET3 constitute a new family of dioxygenases that utilize molecular oxygen and the cofactors Fe(II) and 2-oxoglutarate to convert 5-methylcytosine (5mC) to 5-hydroxy-methylcytosine (5hmC) and further oxidation products in DNA1-5. Here we show that Tet1 and Tet2 have distinct roles in regulating 5hmC deposition and gene expression in mouse embryonic stem cells (mESC). Tet1 depletion in mESC primarily diminishes 5hmC levels at transcription start sites (TSS), whereas Tet2 depletion is mostly associated with decreased 5hmC in gene bodies relative to TSS. 5hmC is enriched at exon start and end sites, especially in exons that are highly expressed, and is significantly decreased upon Tet2 knockdown at the boundaries of high-expressed exons that are selectively regulated by Tet2. In differentiating murine B cells, Tet2 deficiency is associated with selective exon exclusion in the gene encoding the transmembrane phosphatase CD45. Tet2 depletion is associated with increased 5hmC and decreased 5mC at promoters/ TSS regions, possibly because of the redundant activity of Tet1. Together, these data indicate a complex interplay between Tet1 and Tet2 in mESC, and show that loss-of-function of a single TET protein does not necessarily lead to loss of 5hmC and a corresponding gain of 5mC, as generally assumed. The relation between Tet2 loss-of-function and selective changes in exon expression could potentially explain the frequent occurrence of both TET2 loss-of-function mutations and mutations in proteins involved in pre-mRNA splicing in myeloid malignancies in humans. Gene and exon expression analysis in mESC, Tet1 knockdown mESC, and Tet2 knockdown mESC by RNA-sequencing. Mapping of 5-hydroxymethylcytosine in mESC, Tet1 knockdown mESC, and Tet2 knockdown mESC by anti-CMS-seq. Mapping of methylcytosine in mESC, and Tet2 kd mESC by MeDIP-seq.
Project description:The TET proteins TET1, TET2 and TET3 constitute a new family of dioxygenases that utilize molecular oxygen and the cofactors Fe(II) and 2-oxoglutarate to convert 5-methylcytosine (5mC) to 5-hydroxy-methylcytosine (5hmC) and further oxidation products in DNA1-5. Here we show that Tet1 and Tet2 have distinct roles in regulating 5hmC deposition and gene expression in mouse embryonic stem cells (mESC). Tet1 depletion in mESC primarily diminishes 5hmC levels at transcription start sites (TSS), whereas Tet2 depletion is mostly associated with decreased 5hmC in gene bodies relative to TSS. 5hmC is enriched at exon start and end sites, especially in exons that are highly expressed, and is significantly decreased upon Tet2 knockdown at the boundaries of high-expressed exons that are selectively regulated by Tet2. In differentiating murine B cells, Tet2 deficiency is associated with selective exon exclusion in the gene encoding the transmembrane phosphatase CD45. Tet2 depletion is associated with increased 5hmC and decreased 5mC at promoters/ TSS regions, possibly because of the redundant activity of Tet1. Together, these data indicate a complex interplay between Tet1 and Tet2 in mESC, and show that loss-of-function of a single TET protein does not necessarily lead to loss of 5hmC and a corresponding gain of 5mC, as generally assumed. The relation between Tet2 loss-of-function and selective changes in exon expression could potentially explain the frequent occurrence of both TET2 loss-of-function mutations and mutations in proteins involved in pre-mRNA splicing in myeloid malignancies in humans. Gene and exon expression analysis in mESC, Tet1 knockdown mESC, and Tet2 knockdown mESC by RNA-sequencing. Mapping of 5-hydroxymethylcytosine in mESC, Tet1 knockdown mESC, and Tet2 knockdown mESC by anti-CMS-seq. Mapping of methylcytosine in mESC, and Tet2 kd mESC by MeDIP-seq.
Project description:DNA methylation is tightly regulated throughout mammalian development and altered methylation patterns are a hallmark of cancer. The methylcytosine dioxygenase TET2 is frequently mutated in acute myeloid leukemia (AML) and has been suggested to protect CpG islands and promoters from aberrant methylation. By generating a novel mouse model of Tet2-deficient AML we show that loss of Tet2 in hematopoietic cells leads to progressive hypermethylation of active enhancer elements and altered expression of genes implicated in tumorigenesis. In contrast, CpG island and promoter methylation does not change in a Tet2-dependent manner. Furthermore, we confirm this specific enhancer hypermethylation phenotype in human AML patients. Thus, we propose that TET2 prevents leukemic transformation of hematopoietic cells by protecting enhancers from aberrant DNA methylation. ChIP-seq analysis for distribution of H3K4me1, H3K27ac, and H3K4me3 histone marks in in vitro-grown hematopoietic cells transduced with AML1-ETO
Project description:Analysis of total PolII and Ser2-phosphorylated PolII genomic occupancy in control-transfected (WT) or Trim28-knockdown (Trim28-KD) embryonic stem cells. Embryonic stem cells were transfected with luciferase siRNA (WT) or Trim28 siRNA (Trim28 KD) in duplicate experiments. 48 hrs after transfection, cells were crosslinked with formaldehyde, collected, lysed, and chromatin was fragmented with sonication. Total PolII or Ser2-phosphorylated PolII genomic occupancy in WT or Trim28 KD cells were determined by ChIP-seq.
Project description:To understand how CFIm25 associates with genomic DNA during co-transcriptional mRNA processing,we carried out ChIP-seq analysis for CFIm25 in control and CFIm25 KD cells (CFIm25 KD cells as normalization background)