SetDB1 Contributes to Repression of Genes Encoding Developmental Regulators and Maintenance of ES Cell State
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ABSTRACT: Transcription factors that play key roles in regulating embryonic stem (ES) cell state have been identified, but the chromatin regulators that help maintain ES cells are less well understood. A high-throughput shRNA screen was used to identify novel chromatin regulators that influence ES cell state. Loss of histone H3K9 methyltransferases, particularly SetDB1, had the most profound effects on ES cells. ChIP-Seq and functional analysis revealed that SetDB1 and histone H3K9 methylated nucleosomes occupy and repress genes encoding developmental regulators. These SetDB1-occupied genes are a subset of the “bivalent” genes, which contain nucleosomes with H3K4me3 and H3K27me3 modifications catalyzed by trithorax and polycomb group proteins, respectively. These genes are subjected to repression by both polycomb group proteins and SetDB1, and loss of either regulator can destabilize ES cell state.
Project description:Transcription factors that play key roles in regulating embryonic stem (ES) cell state have been identified, but the chromatin regulators that help maintain ES cells are less well understood. A high-throughput shRNA screen was used to identify novel chromatin regulators that influence ES cell state. Loss of histone H3K9 methyltransferases, particularly SetDB1, had the most profound effects on ES cells. ChIP-Seq and functional analysis revealed that SetDB1 and histone H3K9 methylated nucleosomes occupy and repress genes encoding developmental regulators. These SetDB1-occupied genes are a subset of the M-bM-^@M-^\bivalentM-bM-^@M-^] genes, which contain nucleosomes with H3K4me3 and H3K27me3 modifications catalyzed by trithorax and polycomb group proteins, respectively. These genes are subjected to repression by both polycomb group proteins and SetDB1, and loss of either regulator can destabilize ES cell state. ChIP-seq data for SetDB1 and H3K9me3 in mouse ES cells.
Project description:Dynamic regulation of histone methylation by methyltransferases and demethylases plays a central role in regulating the fate of embryonic stem (ES) cells. The histone H3K9 methyltransferase KMT1E, formerly known as ESET or Setdb1, is essential to embryonic development as the ablation of the Setdb1 gene results in peri-implantation lethality and prevents the propagation of ES cells. However, Setdb1- null blastocysts do not display global changes in H3K9 methylation or DNA methylation, arguing against a genome- wide defect. Here we show that conditional deletion of the Setdb1 gene in ES cells results in the upregulation of lineage differentiation markers, especially trophectoderm-specific factors, similar to effects observed upon loss of Oct3/4 expression in ES cells. We demonstrate that KMT1E deficiency in ES cells leads to a decrease in histone H3K9 methylation at and derepression of trophoblast-associated genes such as Cdx2. Furthermore, we find genes that are derepressed upon Setdb1 deletion to overlap with known targets of polycomb mediated repression, suggesting that KMT1E mediated H3K9 methylation acts in concert with polycomb controlled H3K27 methylation. Our studies thus demonstrate an essential role for KMT1E in the control of developmentally regulated gene expression programs in ES cells. Analysis of KMT1E-deficiency in mouse embryonic stem cells using a Setdb1 conditional allele and tamoxifen-inducible Cre/loxP recombination
Project description:Dynamic regulation of histone methylation by methyltransferases and demethylases plays a central role in regulating the fate of embryonic stem (ES) cells. The histone H3K9 methyltransferase KMT1E, formerly known as ESET or Setdb1, is essential to embryonic development as the ablation of the Setdb1 gene results in peri-implantation lethality and prevents the propagation of ES cells. However, Setdb1- null blastocysts do not display global changes in H3K9 methylation or DNA methylation, arguing against a genome- wide defect. Here we show that conditional deletion of the Setdb1 gene in ES cells results in the upregulation of lineage differentiation markers, especially trophectoderm-specific factors, similar to effects observed upon loss of Oct3/4 expression in ES cells. We demonstrate that KMT1E deficiency in ES cells leads to a decrease in histone H3K9 methylation at and derepression of trophoblast-associated genes such as Cdx2. Furthermore, we find genes that are derepressed upon Setdb1 deletion to overlap with known targets of polycomb mediated repression, suggesting that KMT1E mediated H3K9 methylation acts in concert with polycomb controlled H3K27 methylation. Our studies thus demonstrate an essential role for KMT1E in the control of developmentally regulated gene expression programs in ES cells.
Project description:We report the application of single-molecule-based sequencing technology for high-throughput profiling of histone modifications in mammalian cells and characterized genome-wide SetDB1 binding and H3K9 trimethylation (H3K9me3) profiles in mouse ES cells and uncovered two distinct classes of SetDB1 binding sites, termed solo and ensemble peaks. The solo peaks were devoid of H3K9me3 and enriched near developmental regulators while the ensemble peaks were associated with H3K9me3. A subset of the SetDB1 solo peaks, particularly those near neural development related genes, was found to be associated with Polycomb Repressive Complex 2 (PRC2) as well as PRC2-interacting proteins Jarid2 and Mtf2. Genetic deletion of Setdb1 dramatically reduced Ezh2 binding as well as histone 3 lysine 27 (H3K27) trimethylation level at SetDB1 solo peaks and facilitated neural differentiation. Furthermore, we found that H3K27me3 inhibits SetDB1 methyltransferase activity in vitro. The currently identified reciprocal action between SetDB1 and PRC2 reveals a novel mechanism underlying ES cell pluripotency and differentiation regulation. Examination of 2 different histone modifications in 2 cell status.
Project description:We report the application of single-molecule-based sequencing technology for high-throughput profiling of histone modifications in mammalian cells and characterized genome-wide SetDB1 binding and H3K9 trimethylation (H3K9me3) profiles in mouse ES cells and uncovered two distinct classes of SetDB1 binding sites, termed solo and ensemble peaks. The solo peaks were devoid of H3K9me3 and enriched near developmental regulators while the ensemble peaks were associated with H3K9me3. A subset of the SetDB1 solo peaks, particularly those near neural development related genes, was found to be associated with Polycomb Repressive Complex 2 (PRC2) as well as PRC2-interacting proteins Jarid2 and Mtf2. Genetic deletion of Setdb1 dramatically reduced Ezh2 binding as well as histone 3 lysine 27 (H3K27) trimethylation level at SetDB1 solo peaks and facilitated neural differentiation. Furthermore, we found that H3K27me3 inhibits SetDB1 methyltransferase activity in vitro. The currently identified reciprocal action between SetDB1 and PRC2 reveals a novel mechanism underlying ES cell pluripotency and differentiation regulation.
Project description:Polycomb group proteins are essential for early development in metazoans but their contributions to human development are not yet well understood. We have mapped the Polycomb Repressive Complex 2 (PRC2) subunit Suz12 across the entire non-repeat portion of the genome in human embryonic stem (ES) cells. We found that Suz12 is distributed across large portions of over two hundred genes encoding key developmental regulators. These genes are occupied by nucleosomes trimethylated at histone H3K27, are transcriptionally repressed, and contain some of the most highly conserved non-coding elements in the vertebrate genome. We found that preferential activation of PRC2 target genes occurs during differentiation of ES cells into other cell types. The ES cell transcriptional regulators Oct4, Sox2 and Nanog co-occupied a significant subset of these genes, further supporting a link between repression of developmental regulators and stem cell pluripotency. These results indicate that PRC2 occupies a special set of developmental genes in ES cells that must be repressed to maintain pluripotency and that are poised for activation during ES cell differentiation.
Project description:Polycomb group (PcG) proteins are highly conserved from flies to mammals and many of these factors have essential roles in early embryonic development. PcG proteins comprise two multimeric complexes, the Polycomb Repressive complexes 1 and 2 (PRC1 and 2), which have been shown to repress transcription through epigenetic modification of chromatin structure. To gain insight into the role of Polycomb in early development, we have identified PRC1 and PRC2 target genes in mouse embryonic stem (ES) cells using genome-scale location analysis. We found that PRC2 occupies many genes that encode key regulators of development including those encoding transcription factors and components of signaling pathways. These genes are repressed and contain nucleosomes methylated at lysine 27 on histone H3. The majority of PRC2 bound and methylated target genes are co-occupied by PRC1 indicating that these complexes function at a similar set of genes in ES cells. Lack of PRC1 or PRC2 subunits in ES cells results in derepression of target genes and loss of pluripotency. These results provide insight into how PcG proteins contribute to the maintenance of stem cell identity.
Project description:SETDB1 is a major H3K9 methyltransferase. It contains a unique Triple Tudor Domain (3TD) which specifically bind the dual modification of H3K14ac in the presence of H3K9me1/2/3. In this study, we explored the role of the 3TD H3K14ac interaction in the H3K9 methylation activity by SETDB1. We generated the 3TD binding reduced F332A mutant and demonstrate in biochemical methylation assays on recombinant nucleosomes containing H3K14ac analogs, that H3K14 acetylation is crucial for the 3TD mediated recruitment of SETDB1. We also see this effect in the cells where SETDB1 binding and activity was globally correlated with H3K14ac, and knock-out (KO) of the H3K14 acetyltransferase HBO1 caused a drastic reduction in the H3K9me3 levels at SETDB1 dependent sites. Further analyses revealed that 3TD was not required for SETDB1 recruitment for regions targeted by KAP1, but at specific target regions, SETDB1 KO could not be efficiently reconstituted by a 3TD mutant of SETDB1 as shown by the finding that H3K9 methylation of L1M repeat elements is highly dependent on an intact 3TD. In summary, our data demonstrate an important role of the 3TD interaction with H3 tails containing K14ac and K9 methylation in the recruitment of SETDB1 to chromatin which is particularly relevant at L1M repeats.
Project description:Epigenetic regulators play a critical role in normal and malignant hematopoiesis. We recently showed that the Histone 3 Lysine 9 (H3K9) methyltransferase SETDB1 negatively regulates the expression of the pro-leukemic genes HoxA9 and its cofactor Meis1 through deposition of promoter H3K9 trimethylation (H3K9me3) in MLL-AF9 AML cells. Here, we investigated the microbiological impact of altered SETDB1 expression in AML cells. We explored changes in transcription using RNA-seq, promoter associated histone modifications using ChIP-seq, and chromatin accessibility using ATAC-seq. Next generation sequencing of AML cells with or without overexpression of SETDB1 shows that high expression of SETDB1 induces repressive changes to the promoter epigenome and downregulation of genes linked with AML, including Dock1 and the MLL-AF9 target genes Hoxa9, Six1, and others. These data reveal novel targets of SETDB1 in AML that point to a role for SETDB1 in negatively regulating pro-leukemic target genes and suppressing AML.