Project description:We explored the relationship between the evolutionary dynamics of CTCF binding and the functional stability of higher order genome structures, by performing ChIP-seq experiments in closely related Mus species or strains and intersecting with Hi-C-derived topologically associating domains (TADs) and expression data. To complement our data analyses, we generated RNA-seq libraries from two Mus caroli adult male individuals.
Project description:Polycomb proteins play an essential role in maintaining the repression of developmental genes in self-renewing embryonic stem cells. The exact mechanism allowing the derepression of polycomb target genes during cell differentiation remains unclear. Here, we show that several differentiation genes transiently recruit a Cbx8-containing Polycomb repressive complex (PRC) 1 during their early activation. Depletion of Cbx8 partially impairs the transcriptional activation of these genes. This correlates with a reduction in low but detectable levels of histone H3 lysine 27 acetylation. Prolonged gene activation results in eviction of PRC1 despite persisting H3K27me3. The composition of PRC1 is highly modular and changes when ES cells commit to differentiation. We further demonstrate that the exchange of Cbx7 for Cbx8 is required for the effective activation of differentiation genes. Taken together our results establish a function for a Cbx8-containing complex in facilitating the transition from a Polycomb-repressed chromatin state to an active state. As this affects several key regulatory differentiation genes this mechanism is likely to contribute to the robust execution of differentiation programs. Examination of cbx8 in ES E14 mouse cells in 2 condition before and after 72h stimulation with retinoic acid compared with IgG
Project description:The mammalian TET dioxygenases contribute to global waves of DNA demethylation in the zygote and in primordial germ cells, but their involvement during de novo DNA methylation at peri/post-implantation development is unknown. Here, we show novel physiological functions of Tet1 in the pre-primitive streak stage mouse embryo, where it is expressed not only in the primed-state epiblast, but also in the extra-embryonic ectoderm. In the epiblast, Tet1 contributes to DNA methylation patterning, which indirectly results in dominant transcriptional repression involving a Jumonji-family gene Jmjd8. In the extra-embryonic ectoderm, Tet1 suppresses expression of metabolic genes involved in oxidative phosphorylation. These lineage-specific gene repressive functions, involving distinct modes of regulation by DNA methylation, counteract precocious differentiation of the embryo prior to the onset of gastrulation. Such dysregulation in the absence of Tet1 are surprisingly tolerated in an inbred strain but results in full embryonic lethality in non-inbred mice, thus implicating a complex but essential role of Tet1 in normal gestational development.
Project description:The 3D organization of the genome is important for regulation of diverse nuclear processes ranging from transcription to DNA replication. Knowledge of the higher order chromatin structure is critical for understanding mechanisms of gene regulation by long-range control elements such as enhancers and insulators. We describe high resolution, genome-wide dynamic chromatin interaction maps in human embryonic stem cells (hESC) as they differentiate into four distinct embryonic cell lineages. Extensive reorganization of higher-order chromatin structure occurs during hESC differentiation. In this process, topological domains remain largely intact but inter-domain association patterns change dramatically, coincident with widespread changes in chromatin state and gene expression. Moreover, using proximity ligation sequencing to generate chromosome span haplotypes, widespread allele biased gene activities are detected. The allelic gene expression patterns can be correlated to epigenetic state at distal enhancers, supporting the role of these elements in regulating gene expression over a distance. Two biological replicates of Hi-C experiment and one replicate of CTCF ChIP-Seq experiment in embryonic stem cells and 4 other differentiated cell-types from H1 cell line. Re-analysis of data from GSE16256 in an allele specific manner is linked as supplementary data.