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:The MYST HAT Sas2 is part of the SAS-I complex. The target for acetylation by Sas2 is Lys16 of histone H4 (H4 K16Ac). This acetylation site marks euchromatic regions and opposes the spreading of heterochromatin at telomere-proximal regions. Changes of SAS-I-mediated H4 K16Ac on a genome-wide scale comparing wt and sas2M-bM-^HM-^F cells were investigated in this study. We found a pronounced, genome-wide loss of H4 K16 acetylation in the body of transcribed genes in the absence of Sas2. Furthermore, the influence of Sas2 on gene expression was investigated in RNA expression arrays. H4 K16Ac and H4 in wt and sas2M-bM-^HM-^F was ChIPed. ChIP experiments were performed three times with independent chromatin preparations.
Project description:Hat1 WT and Hat1 KO MEFs were grown on both galactose and glucose. Abundance of acetylated peptides was compared between the samples.
Project description:The MYST HAT Sas2 is part of the SAS-I complex. The target for acetylation by Sas2 is Lys16 of histone H4 (H4 K16Ac). This acetylation site marks euchromatic regions and opposes the spreading of heterochromatin at telomere-proximal regions. Changes of SAS-I-mediated H4 K16Ac on a genome-wide scale comparing wt and sas2∆ cells were investigated in this study. We found a pronounced, genome-wide loss of H4 K16 acetylation in the body of transcribed genes in the absence of Sas2. Furthermore, the influence of Sas2 on gene expression was investigated in RNA expression arrays.
Project description:Newly discovered histone lysine acylations increase the functional diversity of nucleosomes well beyond acetylation. Here, we focus on histone butyrylation in the context of sperm cell differentiation. Specifically, we investigate the butyrylation of histone H4 lysine 5 and 8 at gene promoters, where acetylation guides the binding of Brdt, a bromodomain-and-extra-terminal protein, thereby mediating stage-specific gene expression programs. Genome-wide mapping data show that highly active Brdt-bound gene promoters systematically harbour competing histone acetylation and butyrylation marks at H4 K5 and K8. Histone butyrylation, despite acting as a direct stimulator of transcription, competes with acetylation, especially at H4 K5, to prevent Brdt binding. The observed in vivo H4 K5K8 acetylation butyrylation state at active promoters is reproduced in vitro where p300 indistinctly acetylates and butyrylates H4 K5 and K8. Altogether, highly active gene promoter regions are characterized by alternating H4 acetylation and butyrylation sustaining direct gene activation and a dynamic bromodomain binding.
Project description:The histone acetyltransferase Sas2 is part of the SAS-I complex and acetylates lysine 16 of histone H4 (H4 K16Ac) in the genome of Saccharomyces cerevisiae. Sas2-mediated H4 K16Ac is strongest over the coding region of genes with low expression. However, it is unclear how Sas2-mediated acetylation is incorporated into chromatin. Our previous work has shown physical interactions of SAS with the histone chaperones CAF-I and Asf1, suggesting a link between SAS-I mediated acetylation and chromatin assembly. Here, we find that Sas2-dependent H4 K16Ac in bulk histones requires passage of the cells through the S-phase of the cell cycle, and the rate of increase in H4 K16Ac depends on both CAF-I and Asf1, whereas steady-state levels and genome-wide distribution of H4 K16Ac shows only mild changes in their absence. Furthermore, H4 K16Ac is deposited in chromatin at genes upon repression, and this deposition requires the histone chaperone Spt6, but not CAF-I, Asf1, HIR or Rtt106. Altogether, our data indicate that Spt6 controls H4 K16Ac levels by incorporating K16-unacetylated H4 in strongly transcribed genes. Upon repression, Spt6 association is decreased, resulting in less deposition of K16-unacetylated and therefore in a concomitant increase of H4 K16Ac that is recycled during transcription.
Project description:acetylation of histone H4 was studied using ChIP on chip technique in breast epithelial HME1 cell lines overexpressing wt or mutant p53