Project description:Assess chromatin accessibility in WT and mutant ES E14 strains using ATAC-seq. Mutant strains are depleted for subunits of the coactivator complexes SAGA (Supt7l KO) or ATAC (Yeats2, Zzz3) using constitutive knock-out (KO) or the auxin-inducible degron (AID) system.
Project description:SAGA and ATAC are two related transcriptional coactivator complexes, sharing the same histone acetyltransferase (HAT) subunit. The HAT activities of SAGA and ATAC are required for metazoan development but the precise role of the two complexes in RNA polymerase II transcription in mammals is less understood. To determine whether SAGA and ATAC have redundant or specific functions dependent on their HAT activities, we compared the effects of HAT inactivation in each complex with that of inactivation of either SAGA or ATAC core subunits in mouse embryonic stem cells (ESCs). We show that core subunits of SAGA or ATAC subunits are required for complex assembly, mouse ESC growth and self-renewal. Additionally, ATAC, but not SAGA subunits are required for ESC viability by regulating the transcription of translation-related genes. Surprisingly, depletion of specific or shared HAT module subunits caused a global decrease in histone H3K9 acetylation, but did not result in significant phenotypic or transcriptional defects. Thus, our results indicate that SAGA and ATAC are differentially required for viability and self-renewal of mouse ESCs by regulating transcription through different pathways, in a HAT-independent manner.
Project description:Assess H3K9ac levels in WT and mutant ES E14 strains using ChIP-seq. Mutant strains are depleted for subunits of the coactivator complexes SAGA (Supt7l KO) or ATAC (AID-Yeats2) or of HAT subunits (AID-Tada3, Tada2a+Tada2b KO) using constitutive knock-out (KO) or the auxin-inducible degron (AID) system.
Project description:To analyse the genome-wide impact of inactivation of the ATAC or SAGA coactivator complexes on RNA polymerase II (Pol II) transcription, we purified newly synthesized RNA from mutant mouse embryonic stem (ES) cell lines in which subunits of ATAC (Yeats2, Zzz3) or SAGA (Supt7l) are inactivated or depleted. We also performed this analysis in mutant cell lines in which a subunit (Tada3) of the shared histone acetyltransferase activity of these two complexes is depleted. Newly synthesized RNA was purified following the 4sU labelling method (more details in extract protocol). For two wildtype samples, the total RNA input was also analysed.
Project description:To understand the precise mechanism that guide the formation of multisubunit complexes is of key importance. Nascent proteins can find and bind their interaction partners during their translation, leading to co-translational assembly. Here we demonstrate that the distinct modules of ATAC (ADA Two A Containing) and SAGA (SPT ADA GCN5 Acetyltransferase), two lysine acetyl transferase-containing transcription coactivator complexes, assemble co-translationally in the cytoplasm of mammalian cells. Fully assembled SAGA complex forms in the cytoplasm of mammalian cells and cytoplasmic SAGA acetylates non-histones proteins, before imported in the nucleus. In contrast, ATAC has no cytoplasmic functions as it cannot be detected in the cytoplasm of mammalian cells. However, fully assembled endogenous ATAC complex containing two functional modules forms and functions in the nucleus. Thus, the two related co-activators, ATAC and SAGA, assemble by using co-translational pathways, but their subcellular localization, cytoplasmic detectability and functions are distinct.
Project description:Metazoan SAGA and ATAC are distinct multi-subunits complexes that share the same catalytic HAT subunit (GCN5 or PCAF). Here we show that these human HAT complexes are targeted to different genomic loci representing functionally distinct regulatory elements both at broadly expressed and tissue specific genes. While SAGA can principally be found at promoters, ATAC is recruited to promoters and enhancers, yet only its enhancer binding is cell-type specific. Furthermore, we show that ATAC functions at a set of enhancers that are not bound by p300, revealing a new class of enhancers not yet identified. These findings demonstrate important functional differences between SAGA and ATAC coactivator complexes at the level of the genome and define a novel role for the ATAC complex in the regulation of a set of enhancers. Examination of SPT20 in two different cell types.
Project description:We performed ATAC-seq to profile the open chromatin lanscape in primary Chd7 WT and mutant GNPs. By analyzing the differentiate peaks between WT and mutant, we identified Chd7-dependent maintance of open chromatin at many neuronal genes.