Project description:Modifications on histones control important biological processes through their effects on chromatin structure. Methylation at histone H3 lysine 4 (H3K4) by Set1p is found at the 5’end of active genes and contributes to transcriptional activation by recruiting chromatin remodeling enzymes. An adjacent arginine residue (H3R2) is also known to be asymmetrically dimethylated (H3R2me2a) in mammalian cells6, but its location within genes and its function in transcription are unknown. Here we show that H3R2 is also methylated in budding yeast. Using an antibody specific for H3R2me2a in ChIP-on-Chip analysis we determine the distribution of this modification on the entire yeast genome. We find that H3R2me2a is enriched at all heterochromatic loci, at inactive euchromatic genes and at the 3’-end of moderately transcribed genes. In all cases the pattern of H3R2 methylation is mutually exclusive with the presence of trimethylation at H3K4 (H3K4me3). The inverse correlation reflects the fact that methylation at H3R2 disrupts the ability of the Set1-complex to methylate H3K4. H3R2m2a inhibits specifically the trimethylation of H3K4 because it prevents Spp1 (a Set1-methyltranferase subunit) from binding to histone H3. These results indicate that methylation at H3R2 controls the global distribution of H3K4me3 and provides the first mechanistic insight into the function of arginine methylation on chromatin. Keywords: ChIP-chip
Project description:Dimethylation of histone H3 arginine 2 (H3R2me2) maintains transcriptional silencing by inhibiting Set-1 mediated trimethylation of H3K4. Here we demonstrate that arginine 2 is also monomethylated (H3R2me1) in yeast but that its functional characteristics are distinct from H3R2me2: (a) H3R2me1 does not inhibit H3K4 methylation, (b) it is present throughout the coding region of genes and (c) it correlates with active transcription. Collectively, these results indicate that different H3R2 methylated states have defined roles in gene expression.
Project description:Dimethylation of histone H3 arginine 2 (H3R2me2) maintains transcriptional silencing by inhibiting Set-1 mediated trimethylation of H3K4. Here we demonstrate that arginine 2 is also monomethylated (H3R2me1) in yeast but that its functional characteristics are distinct from H3R2me2: (a) H3R2me1 does not inhibit H3K4 methylation, (b) it is present throughout the coding region of genes and (c) it correlates with active transcription. Collectively, these results indicate that different H3R2 methylated states have defined roles in gene expression. hIP-chip analysis was performed to determine the genomic distribution of histone modifications H3R2me1, H3R2me2a, H3K4me3, H3K36me3, and H3K79me3 in the BY4741 yeast strain. ChIP samples were amplified, labelled, and hybridized to 50-mer tiling arrays covering the entire yeast genome at a 64 bp resolution.
Project description:Histone H3K4 methylation is a feature of meiotic recombination hotspots shared by many organisms including plants and mammals. Meiotic recombination is initiated by programmed double strand break (DSB) formation that in budding yeast is directed in gene promoters by histone H3K4 di/trimethylation. This histone modification is indeed recognized by Spp1, a PHD-finger containing protein that belongs to the conserved histone H3K4 methyltransferase Set1 complex. During meiosis, Spp1 binds H3K4me and recruits a DSB protein, Mer2, to promote DSB formation close to gene promoters. How Set1C and Mer2 related functions of Spp1 are connected is not clear.
Project description:We are determining the impact of asparagine starvation on histone H3K4 trimethylation deposition across the genome and how they may affect the gene expression.
Project description:Heart disease is the leading cause of death in the developed world, and its comorbidities such as hypertension, diabetes, and heart failure are accompanied by major transcriptomic changes in the heart. During cardiac dysfunction, which leads to heart failure, there are global epigenetic alterations to chromatin that occur concomitantly with morphological changes in the heart in response to acute and chronic stress. These epigenetic alterations include the reversible methylation of lysine residues on histone proteins. Lysine methylation on histone H3K4 and H3K9 were among the first methylated lysine residues identified and have been linked to gene activation and silencing, respectively. However, much less is known regarding other methylated histone residues, including histone H4K20. Trimethylation of histone H4K20 has been shown to repressive gene expression, however this mark has never been examined in the heart. Here we utilized immunoblotting and mass spectrometry to quantify histone H4K20 trimethylation in three models of cardiac dysfunction. Our results show that lysine methylation at this site is regulated in a biphasic manner leading to increased H420 trimethylation during acute hypertrophic stress and decreased H4K20 trimethylation during sustained ischemic injury and cardiac dysfunction. In addition, we examined publicly available datasets to analyze enzymes that regulate H4K20 methylation and identified one demethylase (KDM7C) and two methyltransferases (KMT5A and SMYD5) which were all upregulated in heart failure patients. This is the first study to examine histone H4K20 trimethylation in the heart and to determine how this post-translational modification is differentially regulated in multiple models of cardiac disease.