ChIP-chip from mouse male and female adult livers and P12.5 embryos with H3K27me3
Ontology highlight
ABSTRACT: The H3K27me3 is a repressive histone mark associated with repressive chromatin and is important for X chromosome inactivation. ChIP-chip of H3K27me3 along the mouse X chromosome in male and female livers and p12.5 embryos demonstrated that H3K27me3 is absent at the genes that escape X inactivation. Comparison of H3K27me3 enrichment along the X chromosome in male and female adult livers and P12.5 embryos
Project description:Epigenetic changes commonly occur in hepatocellular carcinoma (HCC) and are associated with aberrant gene expression. Recently, we demonstrated the pivotal role of abnormal H3K4me3 methylation, which is catalyzed by the menin/MLL, a TrxG family, in HCC development. Meanwhile, there is clear evidence that increasing global levels of H3K27me3 are activated in human primary HCC. To further elucidate the functional relatedness of the repressive H3K27me3 and active H3K4me3 histone remodeling in HCC, we performed H3K27me3 and H3K4me3 ChIP-on-chip screen using three HCC specimens and their adjacent tissues. Comparison of ChIP-on-chip results between tumor(C) and adjacent tissues(N) from three HCC specimens with H3K27me3
Project description:The expansion of repressive epigenetic marks has been implicated in heterochromatin formation during embryonic development, but the general applicability of this mechanism is unclear. Here we show that nuclear rearrangement of repressive histone marks H3K9me3 and H3K27me3 into non-overlapping structural layers characterizes senescence-associated heterochromatic foci (SAHF) formation in human fibroblasts. However, the global landscape of these repressive marks remains unchanged upon SAHF formation, suggesting that in somatic cells heterochromatin can be formed through the spatial repositioning of pre-existing repressively marked histones. This model is reinforced by the correlation of pre-senescent replication timing with both the subsequent layered structure of SAHFs and the global landscape of the repressive marks, allowing us to integrate microscopic and genomic information. Furthermore, modulation of SAHF structure does not affect the occupancy of these repressive marks nor vice versa. These experiments reveal that high-order heterochromatin formation and epigenetic remodeling of the genome can be discrete events. Profile comparison of normal growing (control) and Ras-induced senescent IMR90 cells.
Project description:Epigenetic changes commonly occur in hepatocellular carcinoma (HCC) and are associated with aberrant gene expression. Recently, we demonstrated the pivotal role of abnormal H3K4me3 methylation, which is catalyzed by the menin/MLL, a TrxG family, in HCC development. Meanwhile, there is clear evidence that increasing global levels of H3K27me3 are activated in human primary HCC. To further elucidate the functional relatedness of the active H3K4me3 and repressive H3K27me3 histone remodeling in HCC, we performed H3K4me3 and H3K27me3 ChIP-on-chip screen using three HCC specimens and their adjacent tissues. Comparison of ChIP-on-chip results between tumor(C) and adjacent tissues(N) from three HCC specimens with H3K4me3
Project description:This study describes the epigenetic profiling of the X chromosome during X inactivation. It includes H3K4me3 and H3K27me3 ChIP-Seq profiles of male (E14) and female (LF2 and XT67E1) mouse ES cells, together with their differentiated derivatives (either 4d atRA or 10d EB). It also includes ChIP-chip profiles around the Xic on chromosome X of H3K4me3, H3K27me3, H3K9me2, H3K36me3, Pol II, TBP, H3-Core as well as expression, using male (E14) and female (LF2) mouse ES cells, together with their differentiated derivatives (either 4d atRA or 10d EB). Examination of two different histone modifications in 3 cell lines under 3 conditions using ChIP-Seq. Examination of five different histone modifications two transcription factors and gene expression under three conditions in 2 cell lines using ChIP-chip.
Project description:In mammals, genes located on the X chromosome are present in one copy in XY males and two in XX females. To balance the dosage of X-linked gene expression between the sexes one of the two X chromosomes in females is silenced by X inactivation initiated by up-regulation of the lncRNA (long non-coding RNA) Xist and recruitment of specific chromatin modifiers for silencing. The inactivated X chromosome becomes heterochromatic and visits a specific nuclear compartment adjacent to the nucleolus. We report a novel role for the X-linked lncRNA Firre in anchoring the inactive mouse X chromosome and preserving one of its main epigenetic features, trimethylation of histone H3 at lysine 27 (H3K27me3). Similar to Dxz4, Firre is expressed from a macrosatellite repeat locus associated with a cluster of CTCF and cohesin binding specifically on the inactive X. CTCF binding initially present in both male and female mouse embryonic stem cells was found to be lost from the active X during development. The Firre and Dxz4 loci on the inactive X were preferentially located adjacent to the nucleolus. Knockdown of Firre RNA disrupted perinucleolar targeting and H3K27me3 levels in mouse fibroblasts, demonstrating an important role for this lncRNA in maintenance of one of the main epigenetic features of the X chromosome. There was no X-linked gene reactivation after Firre knockdown; however, a compensatory increase in the expression of chromatin modifier genes implicated in X silencing was observed. In female ES cells Firre RNA knockdown did not disrupt Xist expression/coating nor silencing of G6pdx during differentiation, suggesting that Firre does not play a role in the onset of X inactivation. We conclude that the X-linked lncRNA Firre helps position the inactive X chromosome near the nucleolus and preserve one of its main epigenetic features. Examination of allelic protein-binding or histone modification profiles in Patski cells.
Project description:This analysis includes H3K27me3 profiles along the length of the X-chromosome in male (F2) and female (K4) TS cells and in female TS cells showing local reversals of imprinted X-chromosome inactivation (K4GFP). Data also includes H3K27me3 ChIP-chip profiles in Eed-/- mutant male and female TS cells obtained from Magnuson laboratory (Kalantry S. et al., Nat Cell Biol, 2006). Analysis of H3K27me3 profiles in five different cell populations. Three independent biological replicates for each wild-type female cell population and two independent biological replicates for the wild-type male cell population are provided. The ChIP-chip analysis was also carried out in Eed-/- male and female TS cells lacking H3K27me3 for comparison (one replicate). The array includes approx. 162,5 Mb of the X chromosome and approx. 14,6 Mb of chromosome 17 as a control.
Project description:Recent studies have shown that repressive chromatin machinery, including DNA methyltransferases (DNMTs) and Polycomb Repressor Complexes (PRCs), bind to chromosomes throughout mitosis and their depletion results in increased chromosome size. Enzymes that catalyse H3K9 methylation, such as Suv39h1, Suv39h2, G9a, GLP are also retained by mitotic chromosomes. Surprisingly however, mutants lacking H3K9me3 have unusually small and compact mitotic chromosomes that are associated with increased H3S10ph and H3K27me3 levels. Chromosome size and centromere compaction in these mutants was rescued by providing exogenous Suv39h1, or inhibiting Ezh2 activity. Quantitative proteomic comparisons of native mitotic chromosomes isolated from wildtype versus Suv39h1,2 double null ESCs revealed that H3K9me3 was essential for the efficient retention of bookmarking factors such as Esrrb. These results highlight an unexpected role for repressive heterochromatin domains in preserving transcription factor binding through mitosis, and underscore the importance of H3K9me3 for sustaining chromosome architecture and epigenetic memory during cell division.
Project description:The Polycomb repressive complex 2 (PRC2) is important for the maintenance of stem cell pluripotency and suppression of cell differentiation by promoting histone H3 lysine 27 trimethylation (H3K27me3) and silencing expression of genes regulating differentiation. Here we show decreased expression of BRCA1 promotes EZH2 re-targeting genome wide and enhances H3K27me3 levels at PRC2 target loci in mouse ES cells. R1 mouse ES cells were transfected with control siRNA and Brca1 specific siRNA. At 48h after transfection, cells were harvested and subjected to ChIP assay with Ezh2 antibody. Brca1 wild-type (AB2.2) and Brca1 deficient (PL2F8) mouse ES cells were harvested and subjected to ChIP assay with Ezh2 antibody. Fragmented DNA obtained from ChIP assay was repaired by DNA Terminator End Repair Kit (Lucigen Corporation, Middleton, WI) and purified by QIAquick PCR purification kit. Then two unidirectional linkers JW102 and JW103 were annealed and ligated to the blunt ends DNA at 16M-BM-0C overnight. The purified products were amplified to 2 M-NM-<g by LM-PCR. NimbleGen Mouse ChIP 3x720K RefSeq Promoter Array (Roche) were used for the hybridization. Relative enrichments were calculated by dividing the normalized level of ChIP DNA to that of input DNA at corresponding locus. Labeling, hybridization and washing were carried out according to manufacturerM-bM-^@M-^Ys instructions. Experiments in AB2.2 and PL2F8 cells were performed in duplicate.
Project description:This analysis includes H3K27me3 profiles along the length of the X-chromosome in male (F2) and female (F3) TS cells and in female TS cells showing a complete reversal of X-chromosome inactivation (F3 clone1#A). Analysis of H3K27me3 profiles in three different cell populations. Two independent biological replicates for each cell population are provided. The array includes approx. 162,5 Mb of the X chromosome and approx. 14,6 Mb of chromosome 17 as a control.
Project description:Polycomb group (PcG) proteins including EZH2, SUZ12 and so on, which specifically catalyze trimethylation of histone 3 lysine 27 (H3K27me3), and methylated H3K27 can be recognized by other specific binding proteins to compress chromatin structure, leading to the transcriptional repression of the target genes. To completely understand the epigenetic profile and molecular network of PcG in HCC, we performed ChIP-on-chip screens with EZH2, SUZ12 and H3K27me3 antibodies in HepG2 cells. Comparison of ChIP-on-chip results from EZH2, SUZ12 and H3K27me3.