Project description:Silencers are cis-regulatory elements that down-regulate the expression of target genes. While thousands of silencers have been identified experimentally, a predictive chromatin signature has not been found. H4K20me1 was previously reported to be enriched in silencers, but through reanalysis we found that this enrichment is marginal and was primarily driven by the biased selection of elements used in the screen. We generated H4K20me1 ChIP-seq in Drosophila S2 cells and confirmed that H4K20me1 does not mark transcriptional silencers but instead is associated with active transcription. Transcriptional silencers remain a poorly annotated and difficult to predict class of cis-regulatory elements.
Project description:Chromatin is decorated with diverse histone posttranslational modifications (PTMs) that are involved in regulating chromatin structure and dynamics during various DNA-associated processes such as gene transcription, DNA replication and DNA damage repair. Here, we combine a chemical reporter with mass spectrometry to identify a new class of histone PTM, lysine glutarylation (Kglu), occurring at 27 lysine residues on human core histones. The characterization of an evolutionarily conserved Kglu mark at histone H4 lysine 91 (H4K91glu) using a semisynthetic glutarylated protein reveals that this negatively charged modification greatly destabilizes nucleosome by weakening the interactions between histone H2A/H2B dimers and H3/H4 tetramer in vitro. The replacement of H4K91 by glutamic acid in S. cerevisiae to mimic glutarylation influences chromatin structure and thereby results in a global up-regulation of transcription and defects in cell cycle progression, DNA damage repair and telomere silencing in vivo. In mammalian cells, H4K91glu is mainly enriched at promoter regions of highly expressed genes. A down-regulation of H4K91glu is tightly associated with chromatin condensation during mitosis and in response to DNA damage. The cellular dynamics of H4K91glu is controlled by Sirt7 as a deglutarylase and KAT2A as a glutaryltransferase. This study designates a new histone mark (Kglu) as a new regulatory mechanism for chromatin dynamics.
Project description:Lethal 3 malignant brain tumor 1 (L3MBTL1), a homolog of the Drosophila polycomb tumor suppressor l(3)mbt, contains three tandem MBT repeats (3xMBT) that are critical for transcriptional repression. We recently reported that the 3xMBT repeats interact with mono- and dimethylated lysines in the amino termini of histones H4 and H1b to promote methylation-dependent chromatin compaction. Using a series of histone peptides, we now show that the recognition of mono- and dimethylated lysines in histones H3, H4 and H1.4 (but not their trimethylated or unmodified counterparts) by 3xMBT occurs in the context of a basic environment, requiring a conserved aspartic acid (D355) in the second MBT repeat. Despite the broad range of in vitro binding, the chromatin association of L3MBTL1 mirrors the progressive accumulation of H4K20 monomethylation during the cell cycle. Furthermore, transcriptional repression by L3MBTL1 is enhanced by the H4K20 monomethyltransferase PR-SET7 (to which it binds) but not SUV420H1 (an H4K20 trimethylase) or G9a (an H3K9 dimethylase) and knockdown of PR-SET7 decreases H4K20me1 levels and the chromatin association of L3MBTL1. Our studies identify the importance of H4K20 monomethylation and of PR-SET7 for L3MBTL1 function.
Project description:We identified and characterized a previously undescribed histone mark, lysine benzoylation. This histone mark could be modulated by sodium benzoate (SB), an FDA-approved drug and a widely used chemical food preservative, via generation of benzoyl CoA. By ChIP-seq and RNA-seq analysis, we demonstrate that histone lysine benzoylation marks are involved in regulation of gene expression and associated with diverse biological processes. This study therefore reveals a new type of physiological relevant histone mark and identifies non-conical functions of a widely used chemical food preservative.
Project description:We identified and characterized a previously undescribed histone mark, lysine benzoylation. This histone mark could be modulated by sodium benzoate (SB), an FDA-approved drug and a widely used chemical food preservative, via generation of benzoyl CoA. By ChIP-seq and RNA-seq analysis, we demonstrate that histone lysine benzoylation marks are involved in regulation of gene expression and associated with diverse biological processes. This study therefore reveals a new type of physiological relevant histone mark and identifies non-conical functions of a widely used chemical food preservative.