Project description:TET-family enzymes convert 5-methylcytosine (5mC) to 5-hydroxymethylcytosine (5hmC) in DNA. Tet1 and Tet2 are Oct4-regulated enzymes that together sustain 5hmC in mouse embryonic stem (ES) cells. ES cells depleted of Tet1 by RNAi show diminished expression of the Nodal antagonist Lefty1, and display hyperactive Nodal signalling and skewed differentiation into the endoderm-mesoderm lineage in embryoid bodies in vitro. In Fgf4- and heparin-supplemented culture conditions that favor derivation of trophoblast stem (TS) cells, Tet1-depleted ES cells activate the trophoblast stem cell lineage determinant Elf5 and can colonize the placenta in mid-gestation embryo chimeras. Consistent with these findings, Tet1-depleted ES cells form aggressive hemorrhagic teratomas with increased endoderm, reduced neuroectoderm and ectopic appearance of trophoblastic giant cells. Thus Tet1 functions to regulate the lineage differentiation potential of ES cells. Here, we performed whole-genome transcriptome profiling of ES cells stably depleted of Tet1 by shRNA knockdown (Tet1-kd) cultured in either standard ES cell or in TS cell culture conditions. Gene expression changes in Tet1-kd ES cells were fairly modest compared to control (GFP-kd) cells, although gene ontology (GO) analysis of differentially expressed genes yielded many terms related to embryonic development and cell cycle regulation. In TS cell culture conditions, a core set of genes defining trophectodermal cell differentiation, including Cdx2, Eomes and Tead4, was enriched in Tet1-kd compared to GFP-kd cells. A total of 27 samples were analysed with at least 3 replicates in each group. Control/reference samples comprise ES cells cultured in standard ES cell media (true ES cells) and TS cells cultured in Fgf4/heparin-supplemented (TS) media (true TS cells). We compared Tet1-kd ES cells with GFP-kd ES cells cultured in either ES or TS cell media. In addition, we included a set of Tet1-kd subclones (Tet1-kd-sc) cultured in TS cell condition and a set of untransfected ES cells (parental control) cultured in TS cell condition.
Project description:TET-family enzymes convert 5-methylcytosine (5mC) to 5-hydroxymethylcytosine (5hmC) in DNA. Tet1 and Tet2 are Oct4-regulated enzymes that together sustain 5hmC in mouse embryonic stem (ES) cells. ES cells depleted of Tet1 by RNAi show diminished expression of the Nodal antagonist Lefty1, and display hyperactive Nodal signalling and skewed differentiation into the endoderm-mesoderm lineage in embryoid bodies in vitro. In Fgf4- and heparin-supplemented culture conditions that favor derivation of trophoblast stem (TS) cells, Tet1-depleted ES cells activate the trophoblast stem cell lineage determinant Elf5 and can colonize the placenta in mid-gestation embryo chimeras. Consistent with these findings, Tet1-depleted ES cells form aggressive hemorrhagic teratomas with increased endoderm, reduced neuroectoderm and ectopic appearance of trophoblastic giant cells. Thus Tet1 functions to regulate the lineage differentiation potential of ES cells. Here, we performed whole-genome transcriptome profiling of ES cells stably depleted of Tet1 by shRNA knockdown (Tet1-kd) cultured in either standard ES cell or in TS cell culture conditions. Gene expression changes in Tet1-kd ES cells were fairly modest compared to control (GFP-kd) cells, although gene ontology (GO) analysis of differentially expressed genes yielded many terms related to embryonic development and cell cycle regulation. In TS cell culture conditions, a core set of genes defining trophectodermal cell differentiation, including Cdx2, Eomes and Tead4, was enriched in Tet1-kd compared to GFP-kd cells.
Project description:We attempted to identify candidate genes that are expressed more highly in the ICM than in TE cells. Mouse ES cells are cultured from the ICM, whereas mouse TS cells are cultured from the TE. Although these cells have been cultured in vitro, they represent the in vitro equivalents of the ICM and TE. Therefore, genes which are expressed more highly in ES than TS in microarray studies were good candidates for genes predominantly expressed in the ICM in blastocysts. Keywords: strain or line design
Project description:We attempted to identify candidate genes that are expressed more highly in the ICM than in TE cells. Mouse ES cells are cultured from the ICM, whereas mouse TS cells are cultured from the TE. Although these cells have been cultured in vitro, they represent the in vitro equivalents of the ICM and TE. Therefore, genes which are expressed more highly in ES than TS in microarray studies were good candidates for genes predominantly expressed in the ICM in blastocysts. We attempted to identify candidate genes that are expressed more highly in the ICM than in TE cells. Mouse ES cells are cultured from the ICM, whereas mouse TS cells are cultured from the TE. Although these cells have been cultured in vitro, they represent the in vitro equivalents of the ICM and TE. Therefore, genes which are expressed more highly in ES than TS in microarray studies were good candidates for genes predominantly expressed in the ICM in blastocysts.
Project description:We analyzed the genome-wide binding of Tet1 in control (shScr) and Tet1 knockdown (shTet1) mouse ES cells using two different Tet1 antibodies (Tet1-C and Tet1-N). Furthermore, we generated genome-wide mapping of hydroxymethyl cytosine (hmC) and methyl cytosine (mC). We find that hmC, in contrast to mC, is also found at transcription start sites (TSSs), and that there is a significant overlap between Tet1 binding and hmC positive regions. Surprisingly, our results also suggest, that Tet1 has a role in transcriptional repression. We showed that Tet1 associates with Sin3A co-repressor complex, and by performing ChIP-sequencing of Sin3A, we find co-localisation of Tet1 and Sin3a throughout the genome Examination of Tet1 and Sin3A binding as well as hmC and mC localization in mouse ES cells
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.
Project description:Enzymes catalyzing the methylation of the 5-position of cytosine (mC) have essential roles in regulating gene expression, genome stability, and maintaining cellular identity. Recently Tet1, which is highly expressed in embryonic stem (ES) cells, was found to oxidize the methyl group of mC converting it to 5-hydroxymethyl cytosine (hmC)3. Here, we present the genome-wide mapping of Tet1 and hmC in mouse ES cells. We show that Tet1 binds throughout the genome with the majority of binding sites located at transcription start sites (TSSs) and within genes. Similar to Tet1 and mC, also hmC is found throughout the genome and in particular in gene bodies. However, in contrast to mC, hmC is enriched at TSSs. Tet1 and hmC are associated with genes critical for the control of development and differentiation, which become methylated during differentiation. Surprisingly our results also suggest that Tet1 has a role in transcriptional repression. We show that Tet1 binds to a significant proportion of target genes that are positive for the Polycomb repressive histone mark H3K27me3, and that downregulation of Tet1 also leads to increased expression of a group of Tet1 target genes. In agreement with a potential repressive function, we show that Tet1 associates with the Sin3A co-repressor complex, which also co-localises with Tet1 throughout the genome. We propose that Tet1 fulfils dual functions in transcriptional regulation, where it fine-tunes DNA methylation and associates with the Sin3A co-repressor complex to prevent transcriptional activation. [GSM611209-GSM611217] Control (shScr) or two different Tet1 knockdown (shTet1#4 or shTet1#5) mouse ES cells were used. Each experiment was performed in triplicates. [GSM675884-GSM675889] Control (shScr) or Sin3A knockdown (shSin3A) mouse ES cells were used.Each experiment was performed in triplicates.
Project description:We attempted to identify candidate genes that are expressed more highly in the ICM than in TE cells. Mouse ES cells are cultured from the ICM, whereas mouse TS cells are cultured from the TE. Although these cells have been cultured in vitro, they represent the in vitro equivalents of the ICM and TE. Therefore, genes which are expressed more highly in ES than TS in microarray studies were good candidates for genes predominantly expressed in the ICM in blastocysts.
Project description:Embryonic stem (ES) cells and embryos reversibly pause via chemical mTOR inhibition. In this study, we investigate the tissue-specific response to mTORi-induced pausing in ES and trophoblast stem (TS) cells. To resolve the sequential rewiring of the proteome, we conducted a time-series proteomics experiment at 1, 3, 6, 12, 24, and 48 hours upon induction of pausing, and at 1, 3, 6, 12, 24, and 48 hours upon release of pausing in ES and TS cells. We find that ES, but not TS cells pause reversibly. To optimise developmental pausing conditions, we reasoned that by understanding the difference in pausing response of ES and TS cells, we could identify which pathways are essential for pausing. We found that KEGG pathways related to amino acid degradation, fatty acid degradation, and DNA repair are upregulated in ES cells, but downregulated in TS cells during entry into pausing. Moreover, by targeted metabolomics, we found a depletion of short chain carnitines in the paused ES cells. To extend the length of developmental pausing, we supplemented paused embryos with L-carnitine. The L-carnitine supplementation facilitates lipid usage and prolongs the pausing length by 19 days through the establishment of a more dormant state.