Project description:Genome organization influences transcriptional regulation by facilitating interactions between gene promoters and distal regulatory elements. To analyse distal promoter contacts mediated by the PRC1 complex we used Capture Hi-C (CHi-C) to enrich for promoter-interactions in a HiC library in Ring1a KO and Ring1a/b dKO mouse ES cells.
Project description:Genome organization influences transcriptional regulation by facilitating interactions between gene promoters and distal regulatory elements. To analyse distal promoter contacts we used Capture Hi-C (CHi-C) to enrich for promoter-interactions in a HiC lib
Project description:The glucocorticoid receptor (GR) recruits many coregulators via the well characterized AF2 interaction surface in the GR ligand binding domain, but LIM domain coregulator Hic-5 binds to the relatively uncharacterized tau2 activation domain in the hinge region of GR. Requirement of Hic-5 for glucocorticoid-regulated gene expression in U2OS osteosarcoma cells was defined by Hic-5 depletion and global gene expression analysis. Hic-5 depletion had selective and dramatic effects, positive and negative, on both activation and repression of GR target genes. For some hormone-induced genes, Hic-5 facilitated recruitment of the Mediator complex and RNA polymerase II. In contrast, many genes were not regulated by hormone until Hic-5 was depleted. On these genes Hic-5 acted at a very early step of the regulatory process, preventing efficient GR binding on enhancers, chromatin remodeling, and thus preventing glucocorticoid-driven transcriptional regulation. Overall, Hic-5 has selective and diverse roles on GR target genes, functioning as coactivator on some genes and corepressor on others, and either facilitating or opposing the glucocorticoid-driven actions of GR. Hic-5 exhibits multiple mechanisms of action, either regulating GR binding to DNA and chromatin remodeling, or facilitating later steps in transcription complex assembly. We investigate the relationship between GR and Hic5 and identify classes of genes that respond differently when cells are induced with hormone and when Hic5 is knocked down We knock down Hic-5 (TGFB1I1) in U2OS cells using siRNA (siHic5_2) along with nonspecific siRNA (shNS) and assay gene expression changes at 4 different time points of hormone treatment. We also include non-infected control (NI) as a second control at each time point.
Project description:Several hundred mammalian genes are expressed preferentially from one parental allele due to a process called genomic imprinting. Genomic imprinting is particularly prevalent in extra-embryonic tissue, where it plays an essential role during development. Here, we profiled imprinted gene expression via RNA-Seq in a panel of six mouse trophoblast stem (TSC) lines, which are ex vivo derivatives of a progenitor population that gives rise to the placental tissue of the mouse. We found evidence of imprinted expression for 48 genes, 31 of which had previously been described as imprinted and 17 of which we suggest as candidate imprinted genes. An equal number of maternally and paternally biased genes were detected. Several genes showed variability in imprinted expression between the six TSC lines. Sixteen of the 48 known and candidate imprinted genes were previously or newly annotated noncoding RNAs, and six encoded for a total of 60 annotated microRNAs. Pyrosequencing across a panel of six TSC lines returned levels of imprinted expression that were concordant with RNA-Seq measurements for eight genes examined in all six independently derived TSC lines. Our results solidify TSCs as a cell culture-based experimental model to study genomic imprinting, and provide a quantitative foundation upon which to delineate mechanisms by which the process is maintained in the mouse. RNA-Seq from F1 hybrid TSC lines generated from crosses between Cast and B6 mice.
Project description:Several hundred mammalian genes are expressed preferentially from one parental allele due to a process called genomic imprinting. Genomic imprinting is particularly prevalent in extra-embryonic tissue, where it plays an essential role during development. Here, we profiled imprinted gene expression via RNA-Seq in a panel of six mouse trophoblast stem (TSC) lines, which are ex vivo derivatives of a progenitor population that gives rise to the placental tissue of the mouse. We found evidence of imprinted expression for 48 genes, 31 of which had previously been described as imprinted and 17 of which we suggest as candidate imprinted genes. An equal number of maternally and paternally biased genes were detected. Several genes showed variability in imprinted expression between the six TSC lines. Sixteen of the 48 known and candidate imprinted genes were previously or newly annotated noncoding RNAs, and six encoded for a total of 60 annotated microRNAs. Pyrosequencing across a panel of six TSC lines returned levels of imprinted expression that were concordant with RNA-Seq measurements for eight genes examined in all six independently derived TSC lines. Our results solidify TSCs as a cell culture-based experimental model to study genomic imprinting, and provide a quantitative foundation upon which to delineate mechanisms by which the process is maintained in the mouse.
Project description:To explore the molecular mechanisms and signal pathways induced by restoring tumor suppressor gene HIC-1 on breast cancer cells. We have employed whole genome microarray expression profiling as a discovery platform to identify the differential genes induced by HIC-1 gene activation. Small activating RNA (saRNA) that targeted promoter region was used, and MCF-7 breast cancer cell line was selected as cell model. After 96h for saRNA transfection, the cells were collected and the whole genome expression profiles were analyzed. Three independent experiments were repeated for different groups. With the treshold of p<0.01 and fold change >=2 or <-2, there were 1375 differential expression genes, which are related to cell cycle, apoptosis, cell migration, cell invasion and cell proliferation. SaRNA induced gene expression in human breast cancer cell MCF-7 was measured at 96 hours after transfection by 50 nM saRNA. Three independent experiments were performed for experimental group and control group.
Project description:The glucocorticoid receptor (GR) recruits many coregulators via the well characterized AF2 interaction surface in the GR ligand binding domain, but LIM domain coregulator Hic-5 binds to the relatively uncharacterized tau2 activation domain in the hinge region of GR. Requirement of Hic-5 for glucocorticoid-regulated gene expression in U2OS osteosarcoma cells was defined by Hic-5 depletion and global gene expression analysis. Hic-5 depletion had selective and dramatic effects, positive and negative, on both activation and repression of GR target genes. For some hormone-induced genes, Hic-5 facilitated recruitment of the Mediator complex and RNA polymerase II. In contrast, many genes were not regulated by hormone until Hic-5 was depleted. On these genes Hic-5 acted at a very early step of the regulatory process, preventing efficient GR binding on enhancers, chromatin remodeling, and thus preventing glucocorticoid-driven transcriptional regulation. Overall, Hic-5 has selective and diverse roles on GR target genes, functioning as coactivator on some genes and corepressor on others, and either facilitating or opposing the glucocorticoid-driven actions of GR. Hic-5 exhibits multiple mechanisms of action, either regulating GR binding to DNA and chromatin remodeling, or facilitating later steps in transcription complex assembly. We investigate the relationship between GR and Hic5 and identify classes of genes that respond differently when cells are induced with hormone and when Hic5 is knocked down We knock down Hic-5 (TGFB1I1) in U2OS cells using two different siRNA (siHic5_2 and siHic5_5) along with nonspecific siRNA (shNS) and assay gene expression changes at 4 different time points of hormone treatment. We also include non-infected control (NI) as a second control at each time point.
Project description:Differences in chromatin state inherited from the parental gametes influence the regulation of maternal and paternal alleles in offspring. This phenomenon, known as genomic imprinting, results in genes preferentially transcribed from one parental allele. While local epigenetic factors such as DNA methylation are known to be important for the establishment of imprinted gene expression, less is known about the mechanisms by which differentially methylated regions (DMRs) lead to differences in allelic expression across broad stretches of chromatin. Allele-specific higher-order chromatin structure has been observed at multiple imprinted loci, consistent with the observation of allelic binding of the chromatin-organizing factor CTCF at multiple DMRs. However, whether allelic chromatin structure impacts allelic gene expression is not known for most imprinted loci. Here we characterize the mechanisms underlying brain-specific imprinted expression of the Peg13-Kcnk9 locus, an imprinted region associated with intellectual disability. We performed region capture Hi-C on mouse brain from reciprocal hybrid crosses and found imprinted higher-order chromatin structure caused by the allelic binding of CTCF to the Peg13 DMR. Using an in vitro neuron differentiation system, we show that on the maternal allele, an enhancer-promoter contact formed early in development primes the brain-specific potassium leak channel Kcnk9 for maternal expression prior to neurogenesis. In contrast, this enhancer-promoter contact is blocked by CTCF on the paternal allele, preventing paternal Kcnk9 activation. This work provides a high-resolution map of imprinted chromatin structure and demonstrates that chromatin state established in early development can promote imprinted expression upon differentiation.
Project description:Naive pluripotent epiblast cells of the preimplantation murine embryo and their in vitro counterpart, embryonic stem (ES) cells, have the capacity to give rise to all cells of the adult. Such developmental plasticity is associated with global genome hypomethylation. It is unclear whether genome methylation is dynamically regulated only via differential expression of DNA methyltransferases (DNMTs) and Ten-eleven Translocation (TET) enzymes, which oxidase methylated DNA. Here we show that LIF/Stat3 signalling induces genomic hypomethylation via metabolic reconfiguration. In Stat3-/- ES cells we observed decreased alpha-ketoglutarate (ɑKG) production from reductive Glutamine metabolism, leading to decreased TET activity, increased Dnmt3a/b expression and to a global increase in DNA methylation. Notably, genome methylation is dynamically controlled by simply modulating αKG availability, mitochondrial activity or Stat3 activation in mitochondria, indicating effective crosstalk between metabolism and the epigenome. Stat3-/- ES cells also show increased methylation at Imprinting Control Regions accompanied with differential expression of >50% of imprinted genes. Single-cell transcriptome analysis of Stat3-/- embryos confirmed dysregulated expression of Dnmt3a/b, Tet2, and imprinted genes in vivo. Our results reveal that the LIF/Stat3 signal bridges the metabolic and epigenetic profiles of naive pluripotent cells, ultimately controlling genome methylation and imprinted gene expression. Several imprinted genes regulate cell proliferation and are often misregulated in tumors. Moreover, a wide range of cancers display Stat3-overactivation, raising the possibility that the molecular module we described here is exploited under pathological conditions.