Project description:we report a novel strategy to detect targeted protein and its PTM isoforms in single cells. We barcode the proteins from single cells by tagging them with oligonucleotides, pool barcoded cells together, run bulk gel electrophoresis to separate protein and its PTM isoform and quantify their abundances by sequencing the oligonucleotides associated with each protein species. We used this strategy to measure histone protein H2B and its monoubiquitination isoform, H2Bub, in single yeast cells. Our results revealed the heterogeneities of H2B ubiquitination levels in single cells from different cell-cycle stages, which is obscured in ensemble measurements.
Project description:In eukaryotes, chromatin-based mechanisms superimpose with DNA sequence information to determine the transcriptional output of the genome. Therefore, evaluating the role of chromatin modifications in the regulation of gene expression is key to understand the contribution of chromatin state variations to development. Recent studies identified several transcriptional coactivators that contribute to selectively regulate cellular pathways by coordinating histone H2B monoubiquitination (H2Bub) with other histone modifications. Although H2Bub is present on a large number of genes, loss of H2B monoubiquitination activity was shown to affect RNA steady levels for a small subset of genes and therefore its influence on gene expression is not well understood. In this study we assessed the impact of H2Bub on dynamic expression changes during a rapid developmental tranistion that initiates only when exposing plants to light. This revealed that H2Bub deposition is highly dynamic in a genomic context. Furthermore, plants lacking histone H2B monoubiquitination activity were impaired for rapid changes of RNA levels for a large repertoire of genes, indicating that H2Bub is important for attaining appropriate expression levels /in fine/. Finally, the detection power of the genomic approach has allowed us to define a set of genes impacted by H2Bub dynamics for rapid changes in RNA levels. The purpose of this study was to integrate the genome-wide distribution of H2Bub chromatin mark together with transcriptome profiles of wild-type and /hub1 /mutant plants (accession GSE21922) at three time points during early photomorphogenesis H2Bub epigenome in 5-day-old dark-grown seedlings, H2Bub epigenome in 5-day-old dark-grown seedlings +1h light, and H2Bub epigenome in 5-day-old dark-grown seedlings +6h light 2 biological replicates for each time point in dye-swap - ChIP-chip
Project description:The histone chaperone FACT and histone H2B ubiquitination (H2Bub) facilitate RNA Polymerase II passage through chromatin. It remains unknown to what extent they cooperate in vivo. Here, we used genome-wide, genetic, biochemical and microscopic approaches to dissect their interplay in the fission yeast Schizosaccharomyces pombe. We show that FACT and H2Bub repress antisense transcripts near the 5’ end and inside gene bodies, respectively. The accumulation of these transcripts accompanies with changes at genic nucleosomes in FACT and H2Bub mutants. Moreover, in the H2Bub mutant, FACT binding to histones is stabilized. Interestingly, analysis of FACT-H2Bub double mutants revealed that FACT depletion suppresses genic nucleosome loss in the H2Bub mutant. In addition, FACT, unlike H2Bub, maintains nucleosomes in intergenic regions. This is especially important for subtelomeric gene repression and in compacting chromatin into ‘knobs’. Collectively, our study demonstrates that FACT and H2Bub functionally interact with each other in a genome-context dependent manner. Further, our data indicate an involvement of FACT in higher order chromatin formation outside of euchromatin.
Project description:The histone chaperone FACT and histone H2B ubiquitination (H2Bub) facilitate RNA Polymerase II passage through chromatin. It remains unknown to what extent they cooperate in vivo. Here, we used genome-wide, genetic, biochemical and microscopic approaches to dissect their interplay in the fission yeast Schizosaccharomyces pombe. We show that FACT and H2Bub repress antisense transcripts near the 5’ end and inside gene bodies, respectively. The accumulation of these transcripts accompanies with changes at genic nucleosomes in FACT and H2Bub mutants. Moreover, in the H2Bub mutant, FACT binding to histones is stabilized. Interestingly, analysis of FACT-H2Bub double mutants revealed that FACT depletion suppresses genic nucleosome loss in the H2Bub mutant. In addition, FACT, unlike H2Bub, maintains nucleosomes in intergenic regions. This is especially important for subtelomeric gene repression and in compacting chromatin into ‘knobs’. Collectively, our study demonstrates that FACT and H2Bub functionally interact with each other in a genome-context dependent manner. Further, our data indicate an involvement of FACT in higher order chromatin formation outside of euchromatin.
Project description:The histone chaperone FACT and histone H2B ubiquitination (H2Bub) facilitate RNA Polymerase II passage through chromatin. It remains unknown to what extent they cooperate in vivo. Here, we used genome-wide, genetic, biochemical and microscopic approaches to dissect their interplay in the fission yeast Schizosaccharomyces pombe. We show that FACT and H2Bub repress antisense transcripts near the 5’ end and inside gene bodies, respectively. The accumulation of these transcripts accompanies with changes at genic nucleosomes in FACT and H2Bub mutants. Moreover, in the H2Bub mutant, FACT binding to histones is stabilized. Interestingly, analysis of FACT-H2Bub double mutants revealed that FACT depletion suppresses genic nucleosome loss in the H2Bub mutant. In addition, FACT, unlike H2Bub, maintains nucleosomes in intergenic regions. This is especially important for subtelomeric gene repression and in compacting chromatin into ‘knobs’. Collectively, our study demonstrates that FACT and H2Bub functionally interact with each other in a genome-context dependent manner. Further, our data indicate an involvement of FACT in higher order chromatin formation outside of euchromatin.
Project description:In eukaryotes, chromatin-based mechanisms superimpose with DNA sequence information to determine the transcriptional output of the genome. Therefore, evaluating the role of chromatin modifications in the regulation of gene expression is key to understand the contribution of chromatin state variations to development. Recent studies identified several transcriptional coactivators that contribute to selectively regulate cellular pathways by coordinating histone H2B monoubiquitination (H2Bub) with other histone modifications. Although H2Bub is present on a large number of genes, loss of H2B monoubiquitination activity was shown to affect RNA steady levels for a small subset of genes and therefore its influence on gene expression is not well understood. In this study we assessed the impact of H2Bub on dynamic expression changes during a rapid developmental tranistion that initiates only when exposing plants to light. This revealed that H2Bub deposition is highly dynamic in a genomic context. Furthermore, plants lacking histone H2B monoubiquitination activity were impaired for rapid changes of RNA levels for a large repertoire of genes, indicating that H2Bub is important for attaining appropriate expression levels /in fine/. Finally, the detection power of the genomic approach has allowed us to define a set of genes impacted by H2Bub dynamics for rapid changes in RNA levels. The purpose of this study was to integrate the genome-wide distribution of H2Bub chromatin mark together with transcriptome profiles of wild-type and /hub1 /mutant plants (accession GSE21922) at three time points during early photomorphogenesis
Project description:Ubiquitylation of H2B on lysine 120 (H2Bub) is associated with active transcriptional elongation. H2Bub has been implicated in histone cross-talk and is generally regarded to be a prerequisite for H3K4 and H3K79 tri-methylation in both yeast and mammalian cells. We performed a genome-wide analysis of epigenetic marks during muscle differentiation, and, strikingly, we observed a near-complete loss of H2Bub in the differentiated state. We examined the basis for global loss of this mark and found that the H2B ubiquitin E3 ligase, RNF20, was depleted from chromatin in differentiated myotubes, indicating that recruitment of this protein to genes substantially decreases upon differentiation. Remarkably, during the course of myogenic differentiation, we observed retention and acquisition of H3K4 tri-methylation on a large number of genes in the absence of detectable H2Bub. The Set1 H3K4 trimethylase complex was efficiently recruited to a subset of genes in myotubes in the absence of detectable H2Bub, accounting in part for H3K4 tri-methylation in myotubes. Our studies suggest that H3K4me3 deposition in the absence of detectable H2Bub in myotubes is mediated via Set1 and, perhaps, MLL complexes, whose recruitment does not require H2Bub. Thus, muscle cells represent a novel setting in which to explore mechanisms that regulate histone cross-talk. Mapping of H2Bub in growing myoblasts (MB) and fully differentiated myotubes (MT).