ABSTRACT: Genome wide chromatin maps have shown that spreading repressive histone modifications such as H3K9me3 and H4K20me3 are present on pericentromeric and telomeric repeats and on the inactive X chromosome where H3K27me3 or H3K9me3 alternately modify megabasepair sized domains. However, only a few regions along an autosome of which Homeobox gene clusters are notable examples, have been shown to display spreading of repressive histone modifications. Here we present a ChIP-Chip map of repressive and active histone modifications along mouse Chr.17 in embryonic, fibroblast cells. Our results show that the majority of H3K27me3 modifications form BLOCs rather than focal peaks. H3K27me3 BLOCs modify silent genes of all types and their flanking intergenic regions, indicating a negative correlation between H3K27me3 and transcription. However, non-transcribed gene-poor regions also lacked H3K27me3. We therefore performed a low resolution analysis of whole mouse Chr.17 which revealed that H3K27me3 specifically marks megabasepair sized domains that are enriched for genes, SINEs and active histone modifications. These genic H3K27me3 domains alternate with similar sized gene-poor domains that are deficient in active histone modifications, but enriched for LINE and LTR transposons as well as H3K9me3 and H4K20me3. Thus, a mouse autosome can be seen to contain alternating chromatin bands that predominantly separate genes from one retrotransposons class, which could offer unique chromatin compartments for the specific regulation of genes or the silencing of transposons.
Project description:Genome wide chromatin maps have shown that spreading repressive histone modifications such as H3K9me3 and H4K20me3 are present on pericentromeric and telomeric repeats and on the inactive X chromosome where H3K27me3 or H3K9me3 alternately modify megabasepair sized domains. However, only a few regions along an autosome of which Homeobox gene clusters are notable examples, have been shown to display spreading of repressive histone modifications. Here we present a ChIP-Chip map of repressive and active histone modifications along mouse Chr.17 in embryonic, fibroblast cells. Our results show that the majority of H3K27me3 modifications form BLOCs rather than focal peaks. H3K27me3 BLOCs modify silent genes of all types and their flanking intergenic regions, indicating a negative correlation between H3K27me3 and transcription. However, non-transcribed gene-poor regions also lacked H3K27me3. We therefore performed a low resolution analysis of whole mouse Chr.17 which revealed that H3K27me3 specifically marks megabasepair sized domains that are enriched for genes, SINEs and active histone modifications. These genic H3K27me3 domains alternate with similar sized gene-poor domains that are deficient in active histone modifications, but enriched for LINE and LTR transposons as well as H3K9me3 and H4K20me3. Thus, a mouse autosome can be seen to contain alternating chromatin bands that predominantly separate genes from one retrotransposons class, which could offer unique chromatin compartments for the specific regulation of genes or the silencing of transposons. mapping of H3K27me3 histone modification in one MEF cell line (MEFF)
Project description:Genome wide chromatin maps have shown that spreading repressive histone modifications such as H3K9me3 and H4K20me3 are present on pericentromeric and telomeric repeats and on the inactive X chromosome where H3K27me3 or H3K9me3 alternately modify megabasepair sized domains. However, only a few regions along an autosome of which Homeobox gene clusters are notable examples, have been shown to display spreading of repressive histone modifications. Here we present a ChIP-Chip map of repressive and active histone modifications along mouse Chr.17 in embryonic, fibroblast cells. Our results show that the majority of H3K27me3 modifications form BLOCs rather than focal peaks. H3K27me3 BLOCs modify silent genes of all types and their flanking intergenic regions, indicating a negative correlation between H3K27me3 and transcription. However, non-transcribed gene-poor regions also lacked H3K27me3. We therefore performed a low resolution analysis of whole mouse Chr.17 which revealed that H3K27me3 specifically marks megabasepair sized domains that are enriched for genes, SINEs and active histone modifications. These genic H3K27me3 domains alternate with similar sized gene-poor domains that are deficient in active histone modifications, but enriched for LINE and LTR transposons as well as H3K9me3 and H4K20me3. Thus, a mouse autosome can be seen to contain alternating chromatin bands that predominantly separate genes from one retrotransposons class, which could offer unique chromatin compartments for the specific regulation of genes or the silencing of transposons. Keywords: Chip-chip, chromosome 17 wide unbiased mapping unbiased mapping of several histone modifications on chromosome 17 in two independent MEF cell lines
Project description:Genome wide chromatin maps have shown that spreading repressive histone modifications such as H3K9me3 and H4K20me3 are present on pericentromeric and telomeric repeats and on the inactive X chromosome where H3K27me3 or H3K9me3 alternately modify megabasepair sized domains. However, only a few regions along an autosome of which Homeobox gene clusters are notable examples, have been shown to display spreading of repressive histone modifications. Here we present a ChIP-Chip map of repressive and active histone modifications along mouse Chr.17 in embryonic, fibroblast cells. Our results show that the majority of H3K27me3 modifications form BLOCs rather than focal peaks. H3K27me3 BLOCs modify silent genes of all types and their flanking intergenic regions, indicating a negative correlation between H3K27me3 and transcription. However, non-transcribed gene-poor regions also lacked H3K27me3. We therefore performed a low resolution analysis of whole mouse Chr.17 which revealed that H3K27me3 specifically marks megabasepair sized domains that are enriched for genes, SINEs and active histone modifications. These genic H3K27me3 domains alternate with similar sized gene-poor domains that are deficient in active histone modifications, but enriched for LINE and LTR transposons as well as H3K9me3 and H4K20me3. Thus, a mouse autosome can be seen to contain alternating chromatin bands that predominantly separate genes from one retrotransposons class, which could offer unique chromatin compartments for the specific regulation of genes or the silencing of transposons. Keywords: RNA-chip, chromosome 17 wide expression mapping mouse chromosome 17 wide expression mapping of transcribed genes by hybridization of ds cDNA in two independent MEF cell lines
Project description:Genome wide chromatin maps have shown that spreading repressive histone modifications such as H3K9me3 and H4K20me3 are present on pericentromeric and telomeric repeats and on the inactive X chromosome where H3K27me3 or H3K9me3 alternately modify megabasepair sized domains. However, only a few regions along an autosome of which Homeobox gene clusters are notable examples, have been shown to display spreading of repressive histone modifications. Here we present a ChIP-Chip map of repressive and active histone modifications along mouse Chr.17 in embryonic, fibroblast cells. Our results show that the majority of H3K27me3 modifications form BLOCs rather than focal peaks. H3K27me3 BLOCs modify silent genes of all types and their flanking intergenic regions, indicating a negative correlation between H3K27me3 and transcription. However, non-transcribed gene-poor regions also lacked H3K27me3. We therefore performed a low resolution analysis of whole mouse Chr.17 which revealed that H3K27me3 specifically marks megabasepair sized domains that are enriched for genes, SINEs and active histone modifications. These genic H3K27me3 domains alternate with similar sized gene-poor domains that are deficient in active histone modifications, but enriched for LINE and LTR transposons as well as H3K9me3 and H4K20me3. Thus, a mouse autosome can be seen to contain alternating chromatin bands that predominantly separate genes from one retrotransposons class, which could offer unique chromatin compartments for the specific regulation of genes or the silencing of transposons. Keywords: RNA-chip, chromosome 17 wide expression mapping
Project description:Genome wide chromatin maps have shown that spreading repressive histone modifications such as H3K9me3 and H4K20me3 are present on pericentromeric and telomeric repeats and on the inactive X chromosome where H3K27me3 or H3K9me3 alternately modify megabasepair sized domains. However, only a few regions along an autosome of which Homeobox gene clusters are notable examples, have been shown to display spreading of repressive histone modifications. Here we present a ChIP-Chip map of repressive and active histone modifications along mouse Chr.17 in embryonic, fibroblast cells. Our results show that the majority of H3K27me3 modifications form BLOCs rather than focal peaks. H3K27me3 BLOCs modify silent genes of all types and their flanking intergenic regions, indicating a negative correlation between H3K27me3 and transcription. However, non-transcribed gene-poor regions also lacked H3K27me3. We therefore performed a low resolution analysis of whole mouse Chr.17 which revealed that H3K27me3 specifically marks megabasepair sized domains that are enriched for genes, SINEs and active histone modifications. These genic H3K27me3 domains alternate with similar sized gene-poor domains that are deficient in active histone modifications, but enriched for LINE and LTR transposons as well as H3K9me3 and H4K20me3. Thus, a mouse autosome can be seen to contain alternating chromatin bands that predominantly separate genes from one retrotransposons class, which could offer unique chromatin compartments for the specific regulation of genes or the silencing of transposons. Keywords: Chip-chip, chromosome 17 wide unbiased mapping
Project description:Bivalent chromatin domains consisting of the activating histone 3 lysine 4 trimethylation (H3K4me3) and repressive histone 3 lysine 27 trimethylation (H3K27me3) histone modifications are enriched at developmental genes that are repressed in embryonic stem cells but active during differentiation. However, it is unknown whether another repressive histone modification, histone 4 lysine 20 trimethylation (H4K20me3), co-localizes with activating histone marks in ES cells. Here, we describe the previously uncharacterized coupling of the repressive H4K20me3 heterochromatin mark with the activating histone modifications H3K4me3 and histone 3 lysine 36 trimethylation (H3K36me3), and transcriptional machinery (RNA polymerase II; RNAPII), in ES cells. These newly described bivalent domains consisting of H3K4me3/H4K20me3 are predominantly located in intergenic regions and near transcriptional start sites of active genes, while H3K36me3/H4K20me3 are located in intergenic regions and within gene body regions of active genes. Global sequential ChIP, also termed reChIP-Seq, confirmed the simultaneous presence of H3K4me3 and H4K20me3 at the same genomic regions in ES cells. Genes containing H3K4me3/H4K20me3 exhibit decreased RNAPII pausing and are poised for deactivation of RNAPII binding during differentiation relative to H3K4me3 marked genes. An evaluation of transcription factor (TF) binding motif enrichment revealed that DNA sequence may play a role in shaping the landscape of these novel bivalent domains. Moreover, H3K4me3/H4K20me3 and H3K36me3/H4K20me3 bound regions are enriched with repetitive LINE and LTR elements.
Project description:Heterochromatin-specific histone modifications frequently coexist with mammalian DNA methylation to orchestrate a repressive chromatin state. However, it remains elusive how these epigenetic modifications crosstalk. Here, we report that the first bromoadjacent homology (BAH1) domain and the replication foci targeting sequence (RFTS) of maintenance DNA methyltransferase DNMT1 function as readers for H4K20me3 and H3K9me3, respectively. Engagements of H4K20me3 by BAH1 and H3K9me3 by RFTS ensure localization of DNMT1 to heterochromatin in cells, and cooperate with the RFTS-ubiquitination readout to allosterically stimulate DNMT1 s methylation activity at both global and focal levels. Strikingly, there is intramolecular crosstalk between the RFTS and BAH1 domains, which profoundly impacts the maintenance of DNA methylation and genomic resistance to radiation damage. Together, our study reveals an all-in-one model for DNMT1 in which repressive histone modifications directly influence the cellular landscape of DNA methylation and genomic stability, a process implicative of the DNMT1-related pathogenesis.
Project description:DNA methylation and trimethylated histone H4K20 (H4K20me3) constitute two important epigenetic mechanisms that frequently cooperate in silencing repetitive elements of the mammalian genome. However, it remains elusive how these two modifications crosstalk. Here, we report the specific readout of heterochromatin marks H4K20me3 by the first bromo-adjacent-homology (BAH1) domain of maintenance DNA methyltransferase DNMT1. Engagement of BAH1-H4K20me3 ensures heterochromatin targeting of DNMT1, and cooperates with the previously reported readout of H3K9me3/H3 ubiquitination by the RFTS domain to allosterically stimulate DNMT1’s activity at both global and focal levels. Interplay between RFTS and BAH1 domains profoundly impacts the maintenance of DNA methylation and genomic resistance to radiation damage. Together, our study provides a heterochromatin-regulated model for DNMT1 in which multivalent recognition of repressive histone modifications by DNMT1 directly influence the cellular landscape of DNA methylation and genomic stability.
Project description:Epigenetic regulation of chromatin states is thought to control gene expression programs during lineage specification. However, the roles of repressive histone modifications such as trimethylated histone lysine 20 (H4K20me3) in development and genome stability are largely unknown. Here, we show that depletion of SMYD5, a H4K20me3 methyltransferase, leads to decreased H4K20me3 and H3K9me3 ChIP-Seq levels, and de-repression of endogenous LTR/LINE elements during differentiation. SMYD5 depletion results in chromosomal aberrations and the formation of transformed cells that exhibit decreased H4K20me3 and H3K9me3 levels and an expression signature consistent with multiple human cancers. Moreover, dysregulated gene expression in SMYD5 cancer cells is associated with LTR/ERV elements and decreased H4K20me3. These findings implicate an important role for SMYD5 in maintaining chromosome integrity by regulating heterochromatin and repressing endogenous repetitive DNA elements during differentiation.
Project description:Epigenetic regulation of chromatin states is thought to control gene expression programs during lineage specification. However, the roles of repressive histone modifications such as trimethylated histone lysine 20 (H4K20me3) in development and genome stability are largely unknown. Here, we show that depletion of SMYD5, a H4K20me3 methyltransferase, leads to decreased H4K20me3 and H3K9me3 ChIP-Seq levels, and de-repression of endogenous LTR/LINE elements during differentiation. SMYD5 depletion results in chromosomal aberrations and the formation of transformed cells that exhibit decreased H4K20me3 and H3K9me3 levels and an expression signature consistent with multiple human cancers. Moreover, dysregulated gene expression in SMYD5 cancer cells is associated with LTR/ERV elements and decreased H4K20me3. These findings implicate an important role for SMYD5 in maintaining chromosome integrity by regulating heterochromatin and repressing endogenous repetitive DNA elements during differentiation.