Project description:Ferroptosis is an iron-dependent cell death mechanism characterized by an accumulation of toxic lipid peroxides and membrane rupture. The glutathione dependent enzyme, GPX4 (glutathione peroxidase 4), prevents ferroptosis by reducing these lipid peroxides into non-toxic lipid alcohols. Ferroptosis induction by GPX4 inhibition has emerged as a vulnerability of cancer cells, thus highlighting the need to identify ferroptosis regulators that may be exploited therapeutically. Through genome-wide screens and a series of genetic, genomic, and quantitative imaging approaches, we identify the SWI-SNF ATPases BRM and BRG1 as ferroptosis suppressors. Mechanistically, they directly bind to and catalytically increase chromatin accessibility at NRF2 target loci, thus boosting NRF2 transcriptional output. This primes cells to counter lipid peroxidation and confers resistance to GPX4 inhibition and ferroptosis. Importantly, we demonstrate that the BRM/BRG1-ferroptosis connection can be leveraged to enhance the paralog dependency of BRG1-mutant lung cancer cells on BRM, especially in lines that are less sensitive to BRM inhibition or degradation. Our data reveal ferroptosis induction as a potential avenue for broadening the efficacy of BRM degraders/inhibitors and define a specific genetic context for exploiting GPX4 dependency.
Project description:BRG1-SWI/SNF complex is an important chromatin remodeling complex that involved in various biological processes. Here we described the genome-wide binding of histone acetylation upon BRG1 depletion in mouse embryonic stem cells. Mouse embryonic stem cells were treated with either scrambled siRNA or siRNA against BRG1 for 48 h, and each treatment has three replicates.
Project description:BRG1-SWI/SNF complex is an important chromatin remodeling complex that involved in various biological processes. Here we described the genome-wide binding of histone acetylation upon BRG1 depletion in human embryonic stem cells. Human embryonic stem cells were treated with either scrambled siRNA or siRNA against BRG1 for 48 h, and each treatment has three replicates.
Project description:BRG1-SWI/SNF complex is an important chromatin remodeling complex that involved in various biological processes. Here we described the genome-wide binding of histone acetylation upon BRG1 depletion in human embryonic stem cells.
Project description:BRG1-SWI/SNF complex is an important chromatin remodeling complex that involved in various biological processes. Here we described the genome-wide binding of histone acetylation upon BRG1 depletion in mouse embryonic stem cells.
Project description:Linker histones play a fundamental role in shaping chromatin structure, but how their interaction with chromatin is controlled not well understood. In this study we used a combination of genetic and genomic approaches to explore the regulation of linker histone binding in the yeast, Saccharomyces cerevisiae. Despite the tight correlation between linker-to-core histone ratio and nucleosome repeat length (NRL) observed in many organisms, we found that increasing Hho1 levels did not change the overall NRL in yeast chromatin. While over-expression of Hho1 did not alter nucleosome spacing, it did result in a severe growth defect, which could be rescued by mutations that increased histone acetylation in the cell. Consistent with this, genome-wide analysis of linker histone occupancy revealed an inverse correlation with histone tail acetylation in both yeast and mouse embryonic stem cells. Collectively these results suggest that histone acetylation negatively regulates linker histone binding in S. cerevisiae and other organisms.
Project description:The energetic costs of duplicating chromatin are large and therefore likely depend on nutrient sensing checkpoints and metabolic inputs. By studying chromatin modifiers regulated by epithelial growth factor, we identified histone acetyltransferase 1 (HAT1) as an induced gene that enhances proliferation through coordinating histone production, acetylation and glucose metabolism. In addition to its canonical role as a cytoplasmic histone H4 acetyltransferase, we isolated a HAT1-containing complex bound specifically at promoters of H4 genes. HAT1-dependent transcription of H4 genes required an acetate-sensitive promoter element. HAT1 expression was critical for S-phase progression and maintenance of H3 lysine 9 acetylation at proliferation-associated genes, including histone genes. Therefore, these data describe a feed-forward circuit whereby HAT1 captures acetyl-groups on nascent histones and drives H4 production by chromatin binding to support chromatin replication and acetylation. These findings have important implications for human disease, since high HAT1 levels associate with poor outcomes across multiple cancer types.
Project description:Transcription factor/enhancer interactions determine cell specific gene expression. Here, we followed enhancers during differentiations of embryonic stem (ESCs) to epiblast like cells (EpiLCs). There were highly dynamic changes in histone lysine 27 acetylation at enhancer sites throughout the genome. These sites were enriched for a Foxd3 binding motif, a forkhead transcription factor essential in early embryonic development. Surprisingly, Foxd3 occupied largely mutually exclusive sites in the ESCs versus EpiLCs. Foxd3 bound to nucleosome occupied regions, simultaneously evicting the histones while inhibiting full gene expression through the recruitment of histone deacetylases. Knockout of Foxd3 resulted in hyperacetylation and transcriptional upregulation of neighboring genes, many of which were further upregulated at later stages of differentiation. These data show that Foxd3 primes enhancer sites during pregastrulation by removing nucleosomes, yet suppresses neighboring histone hyperacetylation. Such a mechanism may be common to many transcription factors that prepare enhancers for later gene activation during development. ChIP-seq of H3K4me1, H3K27ac, H3K27me3, p300, H3K4me3, RNA Pol2 and Oct4 in four pluripotent states: embryonic stem cells (ESCs) day 1 ESC differentiation, Epi-like stem cells (EpiLCs), and epiblast stem cells (EpiSCs); ChIP-seq of 3XFlag tagged Foxd3 in ESCs and EpiLCs; ChIP-seq of H3K4me1, H3K27ac, H3K27me3, p300 and H3K4me3 in Foxd3 conditional knockout cells (tamoxifen-inducible) -/+ 36h Tamoxifen treatemnt. ChIP seq of Flag-Foxd3 (third replicate), ChIP-seq of HDAC1 and Brg1 in WT and Foxd3 KO cells and MNase-ChIP-seq of H3K4me1
Project description:The recognition of modified histones by “reader” proteins constitutes a key mechanism regulating gene expression in the chromatin context. Compared with the great variety of readers for histone methylation, few protein modules that recognize histone acetylation are known. Here we show that the evolutionarily conserved YEATS domains constitute a novel family of acetyllysine readers. The human AF9 YEATS domain binds strongly to histone H3K9 acetylation and, to a lesser extent, H3K27 and H3K18 acetylation. Crystal structural studies revealed that AF9 YEATS adopts an eight-stranded immunoglobin fold and utilizes a serine-lined aromatic “sandwiching” cage for acetyllysine readout, representing a novel recognition mechanism that is distinct from that of known acetyllysine readers. Histone acetylation recognition by AF9 is important for the chromatin recruitment of the H3K79 methyltransferase DOT1L. Together, our studies identify the YEATS domain as a novel acetyllysine-binding module, thereby establishing the first direct link between histone acetylation and DOTL1-mediated H3K79 methylation in transcription control. ChIP-seq analysis of AF9, H3K79me3, H3K9ac in Hela cells and H3K79me3 in Hela AF9 knockdown and Hela Dot1L knockdown cells.