Project description:The H3K9me3-specific histone methyltransferase SETDB1 is critical for proper regulation of developmental processes, but the underlying mechanisms are only partially understood. Here, we show that deletion of Setdb1 in mouse fetal liver hematopoietic stem and progenitor cells (HSPCs) results in compromised stem cell function, enhanced myeloerythroid differentiation, and impaired lymphoid development. Notably, Setdb1-deficient HSPCs exhibit reduced quiescence and increased proliferation, accompanied by the acquisition of a lineage-biased transcriptional program. In Setdb1-deficient HSPCs, we identify genomic regions that are characterized by loss of H3K9me3 and increased chromatin accessibility, suggesting enhanced transcription factor (TF) activity. Interestingly, hematopoietic TFs like PU.1 bind these cryptic enhancers in wild-type HSPCs, despite the H3K9me3 status. Thus, our data indicate that SETDB1 restricts activation of nonphysiological TF binding sites which helps to ensure proper maintenance and differentiation of fetal liver HSPCs.
Project description:The H3K9me3-specific histone methyltransferase SETDB1 is critical for proper regulation of developmental processes, but the underlying mechanisms are only partially understood. Here, we show that deletion of Setdb1 in mouse fetal liver hematopoietic stem and progenitor cells (HSPCs) results in compromised stem cell function, enhanced myeloerythroid differentiation, and impaired lymphoid development. Notably, Setdb1-deficient HSPCs exhibit reduced quiescence and increased proliferation, accompanied by the acquisition of a lineage-biased transcriptional program. In Setdb1-deficient HSPCs, we identify genomic regions that are characterized by loss of H3K9me3 and increased chromatin accessibility, suggesting enhanced transcription factor (TF) activity. Interestingly, hematopoietic TFs like PU.1 bind these cryptic enhancers in wild-type HSPCs, despite the H3K9me3 status. Thus, our data indicate that SETDB1 restricts activation of nonphysiological TF binding sites which helps to ensure proper maintenance and differentiation of fetal liver HSPCs.
Project description:The H3K9me3-specific histone methyltransferase SETDB1 is critical for proper regulation of developmental processes, but the underlying mechanisms are only partially understood. Here, we show that deletion of Setdb1 in mouse fetal liver hematopoietic stem and progenitor cells (HSPCs) results in compromised stem cell function, enhanced myeloerythroid differentiation, and impaired lymphoid development. Notably, Setdb1-deficient HSPCs exhibit reduced quiescence and increased proliferation, accompanied by the acquisition of a lineage-biased transcriptional program. In Setdb1-deficient HSPCs, we identify genomic regions that are characterized by loss of H3K9me3 and increased chromatin accessibility, suggesting enhanced transcription factor (TF) activity. Interestingly, hematopoietic TFs like PU.1 bind these cryptic enhancers in wild-type HSPCs, despite the H3K9me3 status. Thus, our data indicate that SETDB1 restricts activation of nonphysiological TF binding sites which helps to ensure proper maintenance and differentiation of fetal liver HSPCs.
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:During mammalian development DNA methylation patterns need to be reset in primordial germ cells (PGC) and preimplantation embryos. However, many retro-transposons and imprinted genes are resistant to such global epigenetic reprogramming via hitherto undefined mechanisms. Here, we report that some of these sequences are immune to widespread erasure of DNA methylation in the mouse embryonic stem cells (mESCs) lacking de novo DNA methyltransferases. Persistence of DNA methylation at these loci in mESCs depends on the histone H3K9 methyltransferase Setdb1, as deletion of Setdb1 results in reduction of H3K9me3 and DNA methylation levels concomitant with an increase in 5-hydroxymethylation (5hmC). In addition, depletion of H3K9 methyltransferase G9a leads to genome-wide reduction of DNA methylation but to a lesser extent at the above sequences. Taken together, these data reveal that Setdb1 ensures the fidelity of DNA methylation at specific loci in mESCs, which may reflect mechanisms functioning in vivo during key developmental stages. Examination of H3K9me3 histone modifications in 2 cell types.
Project description:During mammalian development DNA methylation patterns need to be reset in primordial germ cells (PGC) and preimplantation embryos. However, many retro-transposons and imprinted genes are resistant to such global epigenetic reprogramming via hitherto undefined mechanisms. Here, we report that some of these sequences are immune to widespread erasure of DNA methylation in the mouse embryonic stem cells (mESCs) lacking de novo DNA methyltransferases. Persistence of DNA methylation at these loci in mESCs depends on the histone H3K9 methyltransferase Setdb1, as deletion of Setdb1 results in reduction of H3K9me3 and DNA methylation levels concomitant with an increase in 5-hydroxymethylation (5hmC). In addition, depletion of H3K9 methyltransferase G9a leads to genome-wide reduction of DNA methylation but to a lesser extent at the above sequences. Taken together, these data reveal that Setdb1 ensures the fidelity of DNA methylation at specific loci in mESCs, which may reflect mechanisms functioning in vivo during key developmental stages. Examination of gene expression in 2 cell types by RNA-seq.
Project description:During mammalian development DNA methylation patterns need to be reset in primordial germ cells (PGC) and preimplantation embryos. However, many retro-transposons and imprinted genes are resistant to such global epigenetic reprogramming via hitherto undefined mechanisms. Here, we report that some of these sequences are immune to widespread erasure of DNA methylation in the mouse embryonic stem cells (mESCs) lacking de novo DNA methyltransferases. Persistence of DNA methylation at these loci in mESCs depends on the histone H3K9 methyltransferase Setdb1, as deletion of Setdb1 results in reduction of H3K9me3 and DNA methylation levels concomitant with an increase in 5-hydroxymethylation (5hmC). In addition, depletion of H3K9 methyltransferase G9a leads to genome-wide reduction of DNA methylation but to a lesser extent at the above sequences. Taken together, these data reveal that Setdb1 ensures the fidelity of DNA methylation at specific loci in mESCs, which may reflect mechanisms functioning in vivo during key developmental stages. Examination of genome-wide DNA methylation status in 3 cell types.
Project description:During mammalian development DNA methylation patterns need to be reset in primordial germ cells (PGC) and preimplantation embryos. However, many retro-transposons and imprinted genes are resistant to such global epigenetic reprogramming via hitherto undefined mechanisms. Here, we report that some of these sequences are immune to widespread erasure of DNA methylation in the mouse embryonic stem cells (mESCs) lacking de novo DNA methyltransferases. Persistence of DNA methylation at these loci in mESCs depends on the histone H3K9 methyltransferase Setdb1, as deletion of Setdb1 results in reduction of H3K9me3 and DNA methylation levels concomitant with an increase in 5-hydroxymethylation (5hmC). In addition, depletion of H3K9 methyltransferase G9a leads to genome-wide reduction of DNA methylation but to a lesser extent at the above sequences. Taken together, these data reveal that Setdb1 ensures the fidelity of DNA methylation at specific loci in mESCs, which may reflect mechanisms functioning in vivo during key developmental stages. Examination of genome-wide DNA hydroxy-methylation status in 3 cell types.
Project description:During mammalian development DNA methylation patterns need to be reset in primordial germ cells (PGC) and preimplantation embryos. However, many retro-transposons and imprinted genes are resistant to such global epigenetic reprogramming via hitherto undefined mechanisms. Here, we report that some of these sequences are immune to widespread erasure of DNA methylation in the mouse embryonic stem cells (mESCs) lacking de novo DNA methyltransferases. Persistence of DNA methylation at these loci in mESCs depends on the histone H3K9 methyltransferase Setdb1, as deletion of Setdb1 results in reduction of H3K9me3 and DNA methylation levels concomitant with an increase in 5-hydroxymethylation (5hmC). In addition, depletion of H3K9 methyltransferase G9a leads to genome-wide reduction of DNA methylation but to a lesser extent at the above sequences. Taken together, these data reveal that Setdb1 ensures the fidelity of DNA methylation at specific loci in mESCs, which may reflect mechanisms functioning in vivo during key developmental stages. Examination of genome-wide DNA methylation status in 2 cell types.
Project description:During mammalian development DNA methylation patterns need to be reset in primordial germ cells (PGC) and preimplantation embryos. However, many retro-transposons and imprinted genes are resistant to such global epigenetic reprogramming via hitherto undefined mechanisms. Here, we report that some of these sequences are immune to widespread erasure of DNA methylation in the mouse embryonic stem cells (mESCs) lacking de novo DNA methyltransferases. Persistence of DNA methylation at these loci in mESCs depends on the histone H3K9 methyltransferase Setdb1, as deletion of Setdb1 results in reduction of H3K9me3 and DNA methylation levels concomitant with an increase in 5-hydroxymethylation (5hmC). In addition, depletion of H3K9 methyltransferase G9a leads to genome-wide reduction of DNA methylation but to a lesser extent at the above sequences. Taken together, these data reveal that Setdb1 ensures the fidelity of DNA methylation at specific loci in mESCs, which may reflect mechanisms functioning in vivo during key developmental stages. Examination of H3K9me3 histone modifications in 2 cell types.