Project description:H2A.B is a unique histone H2A variant that shares only 40 ~ 50 % sequence identity with canonical H2A. It has only been identified in mammals and has quickly evolved with remarkable sequence diversity among different species. H2A.B is ubiquitously expressed in most cells and tissues. It is mainly deposited in gene body region.The localization of H2A.B is associated with methylated CpG islands in mouse ES cells.H2A.B facilitates transcription elongation to go through methylated CpG islands in the gene bodies. One typical example is that H2A.B regulates transcription elongation at imprinted loci. We used microarray to test the function of H2A.B on gene expression. Mouse ES cells infected with control knockdown(KD) or H2A.B KD virus were treated with G418. ES cells were extracted for RNA and hybridization on Affymetrix microarrays.
Project description:H2A.B is a unique histone H2A variant that shares only 40 ~ 50 % sequence identity with canonical H2A. It has only been identified in mammals and has quickly evolved with remarkable sequence diversity among different species. H2A.B is ubiquitously expressed in most cells and tissues. It is mainly deposited in gene body region. The localization of H2A.B is associated with methylated CpG islands in mouse ES cells. H2A.B facilitates transcription elongation to go through methylated CpG islands in the gene bodies. One typical example is that H2A.B regulates transcription elongation at imprinted loci. We found H2A.B enriched in some methylated loci. Using ChIP-seq and MeDIP-seq, we test the correlation of H2A.B and DNA methylation.
Project description:Reprogramming of ES cells towards the trophoblast lineage, and specifally into self-renewing TS cells, can seemingly be achieved by manipulation of transcription factors such as Cdx2 and Oct4, or modulation of signalling cascades, notably Ras signalling. Here we analyze the arising cells from such treatment in detail for the efficiency and completeness of the reprogramming process. We find that the reprogrammed cells retain an epigenetic and transcriptional memory of their ES cell origin and are not equal to bona fide trophectoderm-derived TS cells. DNA methylation analysis in conventional ES and TS cells and various ES-to-TS reprogramming models
Project description:Epigenetic modification of the mammalian genome by DNA methylation (5-methylcytosine) has a profound impact on chromatin structure, gene expression and maintenance of cellular identity. Recent demonstration that members of the Ten-eleven translocation (Tet) family proteins can convert 5-methylcytosine (5mC) to 5-hydroxymethylcytosine (5hmC) raised the possibility that Tet proteins are capable of establishing a distinct epigenetic state. We have recently demonstrated that Tet1 is specifically expressed in murine embryonic stem (ES) cells and is required for ES cell self-renewal and maintenance. Using chromatin immunoprecipitation coupled with high-throughput DNA sequencing (ChIP-seq), here we show that Tet1 is preferentially bound to CpG-rich sequences at promoters of both transcriptionally active and Polycomb-repressed genes. Despite a general increase in levels of DNA methylation at Tet1 binding-sites, Tet1 depletion does not lead to down-regulation of all the Tet1 targets. Interestingly, while Tet1-mediated promoter hypomethylation is required for maintaining the expression of a group of transcriptionally active genes, it is also required for repression of Polycomb-targeted developmental regulators. Tet1 contributes to silencing of this group of genes by facilitating recruitment of PRC2 to CpG-rich gene promoters. Thus, our study not only establishes a role for Tet1 in modulating DNA methylation levels at CpG-rich promoters, but also reveals a dual function of Tet1 in promoting transcription of pluripotency factors as well as participating in the repression of Polycomb-targeted developmental regulators. To determine the genome-wide distribution of Tet1 in mouse ES cells, we have performed ChIP-seq experiments using Tet1 antibodies in control knockdown (KD) and Tet1 KD ES cells.
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:Polycomb repressive complex 1 (PRC1) catalyzes H2A monoubiquitination (uH2A) and regulates pluripotency in embryonic stem cells (ESCs). However the mechanisms controlling PRC1 recruitment and activity are largely unknown. Here we show that Fbxl10 interacts with Ring1B and Nspc1, forming a non-canonical PRC1. We demonstrate that Fbxl10-PRC1 is essential for H2A ubiquitination in mouse ESCs. Genome-wide analyses reveal that Fbxl10 preferentially binds to CpG islands and co-localizes with Ring1B on Polycomb target genes. Notably, Fbxl10 depletion causes modest dissociation of Ring1B but a major loss of uH2A on target genes. Furthermore rescue experiments for Fbxl10 reveal that its DNA binding capability and integration into PRC1 are required for proper H2A ubiquitination. ES cells lacking Fbxl10, like previously characterized Polycomb mutants, show a severely compromised capacity for successful differentiation. Our results shed light on a novel mechanism how CpG islands regulate chromatin function by affecting polycomb recruitment and activity. All ChIP-seq reactions were performed in either untransfected cells, cells expressing scrambled shRNA or Fbxl10 shRNA, Ring1b-/- or Suz12-/- mouse ES cells
Project description:Pluripotent stem cells have been shown to have unique nuclear properties, e.g., hyperdynamic chromatin and large, condensed nucleoli. However, the contribution of the latter unique nucleolar character to pluripotency has not been well understood. Here, we show fibrillarin (FBL), a critical methyltransferase for ribosomal RNA (rRNA) processing in nucleoli, as one of the proteins highly expressed in pluripotent embryonic stem (ES) cells. Stable expression of FBL in ES cells prolonged the pluripotent state of mouse ES cells cultured in the absence of leukemia inhibitory factor (LIF). Analyses using deletion mutants and a point mutant revealed that the methyltransferase activity of FBL regulates stem cell pluripotency. Knock down of this gene led to significant delays in rRNA processing, growth inhibition, and apoptosis in mouse ES cells. Interestingly, both partial knock down of FBL and treatment with actinomycin D, an inhibitor for rRNA synthesis, induced the expression of differentiation markers in the presence of LIF and promoted stem cell differentiation into neuronal lineages. Moreover, we identified p53 signaling as the regulatory pathway for pluripotency and differentiation of ES cells. These results suggest that proper activity of rRNA production in nucleoli is a novel factor for the regulation of pluripotency and differentiation ability of ES cells. Tc-inducible FBL-knock down ES cells were cultured for 2 days with or without Tc in the presence of LIF. These 2 conditions were analysed transcription profile.
Project description:Epigenetic modification of the mammalian genome by DNA methylation (5-methylcytosine) has a profound impact on chromatin structure, gene expression and maintenance of cellular identity. Recent demonstration that members of the Ten-eleven translocation (Tet) family proteins can convert 5-methylcytosine (5mC) to 5-hydroxymethylcytosine (5hmC) raised the possibility that Tet proteins are capable of establishing a distinct epigenetic state. We have recently demonstrated that Tet1 is specifically expressed in murine embryonic stem (ES) cells and is required for ES cell self-renewal and maintenance. Using chromatin immunoprecipitation coupled with high-throughput DNA sequencing (ChIP-seq), here we show that Tet1 is preferentially bound to CpG-rich sequences at promoters of both transcriptionally active and Polycomb-repressed genes. Despite a general increase in levels of DNA methylation at Tet1 binding-sites, Tet1 depletion does not lead to down-regulation of all the Tet1 targets. Interestingly, while Tet1-mediated promoter hypomethylation is required for maintaining the expression of a group of transcriptionally active genes, it is also required for repression of Polycomb-targeted developmental regulators. Tet1 contributes to silencing of this group of genes by facilitating recruitment of PRC2 to CpG-rich gene promoters. Thus, our study not only establishes a role for Tet1 in modulating DNA methylation levels at CpG-rich promoters, but also reveals a dual function of Tet1 in promoting transcription of pluripotency factors as well as participating in the repression of Polycomb-targeted developmental regulators. Mouse ES cells infected with control knockdown (KD) or Tet1 KD lentiviruses were FACS-sorted for RNA extraction and hybridization on Affymetrix microarrays. We also investigated the effect of Nanog overexpression (OE) in Tet1 KD mouse ES cells on dys-regulated Tet1 targets. We have collected four biologically independent replicates for each treatment.