Project description:Histone acetyltransferases (HAT) assemble into multisubunit complexes in order to target distinct lysine residues on nucleosomal histones. Here, we characterize native HAT complexes assembled by the BRPF-family of scaffold proteins. Their PHD-ZnKnuckle-PHD domain is essential for binding chromatin and restricted to unmethylated H3K4, a specificity that is reversed by the associated ING subunit. Native BRPF1 complexes can contain either MOZ/MORF or HBO1 as catalytic acetyltransferase subunit. Interestingly, while the previously reported HBO1 complexes containing JADE scaffold proteins target histone H4, the HBO1-BRPF1 complex acetylates only H3 in chromatin. We mapped a small region at the N-terminus of scaffold proteins responsible for histone tail selection on chromatin. Thus, alternate choice of subunits associated with HBO1 can switch its specificity from H4 to H3 tails, highlighting a crucial new role of associated subunits within HAT complexes, previously thought to be intrinsic to the catalytic subunit. Genome-wide mapping of MYST acetyltransferases subunits and H3K4me3 histone mark in RKO cells.
Project description:Histone acetyltransferases (HAT) assemble into multisubunit complexes in order to target distinct lysine residues on nucleosomal histones. Here, we characterize native HAT complexes assembled by the BRPF-family of scaffold proteins. Their PHD-ZnKnuckle-PHD domain is essential for binding chromatin and restricted to unmethylated H3K4, a specificity that is reversed by the associated ING subunit. Native BRPF1 complexes can contain either MOZ/MORF or HBO1 as catalytic acetyltransferase subunit. Interestingly, while the previously reported HBO1 complexes containing JADE scaffold proteins target histone H4, the HBO1-BRPF1 complex acetylates only H3 in chromatin. We mapped a small region at the N-terminus of scaffold proteins responsible for histone tail selection on chromatin. Thus, alternate choice of subunits associated with HBO1 can switch its specificity from H4 to H3 tails, highlighting a crucial new role of associated subunits within HAT complexes, previously thought to be intrinsic to the catalytic subunit.
Project description:We used ChIP-seq technology in order to map chromatin binding sites of the HBO1 MYST complex in the RKO cell line. We obtained a significant enrichment of the HBO1 signal right after TSS regions of genes and also In the proximal promoter region, with no signal on TSS. This enrichment also correlates with gene expression level. HBO1 signal in RKO cell line.
Project description:Nasopharyngeal carcinoma (NPC) is causally linked to Epstein-Barr virus (EBV) infection, genetic predisposition and environmental factors. Early diagnosis is difficult due to lack of specific symptoms. Many patients have advanced disease at diagnosis and these patients respond to treatment poorly. To better understand the NPC molecular pathogenesis, genome-wide CRISPR screen was used to identify NPC dependency factors. These dependency factors were then linked to their enhancers using H3K27ac HiChIP. The screen identified MYST histone acetyl transferase complex, NF-kB signaling pathway, purine synthesis pathway, linear ubiquitination pathway, SLC2A1, MDM2, and PIK3C3 as NPC dependency factors/pathways. Importantly, H3K27ac HiChIP linked most of these dependency factors to super-enhancers. This study provided new insight to NPC pathogenesis and also identified novel potential targets for therapy.
Project description:We used ChIP-seq technology in order to map chromatin binding sites of the HBO1 MYST complex in the RKO cell line. We obtained a significant enrichment of the HBO1 signal right after TSS regions of genes and also In the proximal promoter region, with no signal on TSS. This enrichment also correlates with gene expression level.
Project description:RKO cells were treated with low doses of aphidicolin (0.2µM) that inhibit replicative DNA polymerases and induce a mild replication stress. ATAC-seq data were analysed on control cells (DMSO) and after 16h of treatment with aphidicolin
Project description:The restructuring of chromatin precedes tightly regulated events such as DNA transcription, replication, and repair. One type of chromatin remodeling involves the covalent modification of nucleosomes by histone acetyltransferase (HAT) complexes. The observation that apicidin exerts antiprotozoal activity by targeting a histone deacetyltransferase has prompted our search for more components of the histone modifying machinery in parasitic protozoa. We have previously identified GNAT family HATs in the opportunistic pathogen Toxoplasma gondii and now describe the first MYST (named for members MOZ, Ybf2/Sas3, Sas2, and Tip60) family HATs in apicomplexa (TgMYST-A and -B). The TgMYST-A genomic locus is singular and generates a approximately 3.5-kb transcript that can encode two proteins of 411 or 471 amino acids. TgMYST-B mRNA is approximately 7.0 kb and encodes a second MYST homologue. In addition to the canonical MYST HAT catalytic domain, both TgMYST-A and -B possess an atypical C2HC zinc finger and a chromodomain. Recombinant TgMYST-A exhibits a predilection to acetylate histone H4 in vitro at lysines 5, 8, 12, and 16. Antibody generated to TgMYST-A reveals that both the long and short (predominant) versions are present in the nucleus and are also plentiful in the cytoplasm. Moreover, both TgMYST-A forms are far more abundant in rapidly replicating parasites (tachyzoites) than encysted parasites (bradyzoites). A bioinformatics survey of the Toxoplasma genome reveals numerous homologues known to operate in native MYST complexes. The characterization of TgMYST HATs represents another important step toward understanding the regulation of gene expression in pathogenic protozoa and provides evolutionary insight into how these processes operate in eukaryotic cells in general.