Project description:R-loops are prevalent three-stranded nucleic acid structures, composed of a DNA:RNA hybrid and a displaced single-stranded DNA loop. Although aberrant R-loop formation is a threat to genome stability, R-loops are enriched at CpG islands (CGI) and are implicated in maintaining CGI promoters unmethylated. Mapping of genomic regions where Tet1 binds in an R-loop dependent manner we here identify almost exclusively CGIs. The results suggest that R-loops are genomic address labels for TET1.
Project description:To identify direct transcriptional targets of RFX6, we performed chromatin immunoprecipitation of HA epitope tagged RFX6 followed by massively parallel DNA sequencing (ChIP-seq). Using CRISPR/Cas9 gene editing, the HA epitope was inserted into the 3' end of the RFX6 gene in H9 hESC. Pluripotent cells were then differentiated into PDX1+RFX6+ pancreatic progenitors and endogenous RFX6-HA was immunoprecipitated with an anti-HA antibody. To eliminate background signal caused by non-specific antibody binding, a control experiment using wild-type H9 hESC was performed in parallel.
Project description:This experiment was designed to indentify RNAs making direct contact with EZH2 in mouse embryonic stem cells E14 with an integrated transgene encoding HA-EZH2 were pulsed with 4-SU, irradiated with UV, and subjected to HA immunoprecipitation.
Project description:TET1 maintains hypomethylation at bivalent promoters through its catalytic activity in embryonic stem cells (ESCs). However, whether and how TET1 exerts catalytic activity-independent functions in regulating bivalent genes is not well understood. Therefore, we mapped the TET1 interactome in mouse ESCs using a SILAC IP-MS proteomics approach.
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:We have performed ChIP seq analysis to obtain the positions of KAP1 and ZFP57 binding sites in mouse ES cells. By comparing the two lists, we were able to find bona fide sites. ChIP-Seq of HA tagged ZFP57 and KAP1 in mouse ES cells
Project description:In order to assess Tet1 binding, we first generated a Flag tagged Tet1 ES cells and then knocked out Dnmt3a in the [WT, Tet1-Flag] cells. By Tet1 ChIP and Flag ChIP, we showed that Tet1 binding was complementary to Dnmt3a. And Tet1 binding was not affected or slightly increased at majority of its targets.
Project description:TFE3 is a bHLH-ZIP transcription factor, which nuclear localization is regulated by a tumor suppressor FLCN. In order to analyze TFE3 occupancy in whole genome, we have generated and utilized a HK-2 HA-TFE3-inducible cell line which express HA-tagged TFE3 in a doxycycline-dependent manner. HA-TFE3 bound regions were determined by ChIPSeq.