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Supt3 mutant nascent RNA-seq

ABSTRACT: Coactivator complexes regulate chromatin accessibility and transcription. SAGA (Spt-Ada-Gcn5 Acetyltransferase) is an evolutionary conserved coactivator complex. The core module scaffolds the entire SAGA complex and adopts a histone octamer-like structure, which consists of six histone fold domain (HFD)-containing proteins forming three histone fold (HF) pairs, to which the double HFD-containing SUPT3H adds an HF pair. Spt3, the yeast ortholog of SUPT3H, interacts genetically and biochemically with the TATA binding protein (TBP) and contributes to global RNA polymerase II (Pol II) transcription. Here we demonstrate that i) SAGA purified from human U2OS or mouse embryonic stem cells (mESC) can assemble without SUPT3H; ii) SUPT3H is not essential for mESC survival, iii) SUPT3H is required for mESC growth and self-renewal, and iv) the loss of SUPT3H from mammalian cells affects the transcription of only a specific subset of genes. Accordingly, in the absence of SUPT3H no major change in TBP accumulation at gene promoters was observed. Thus, SUPT3H is not required for the assembly of SAGA, TBP recruitment, or overall Pol II transcription, but plays a role in mESC growth and self-renewal. Our data further suggest that yeast and mammalian SAGA complexes contribute to transcription regulation by distinct mechanisms.

ORGANISM(S): Mus musculus

PROVIDER: GSE202823 | GEO | 2022/07/07

REPOSITORIES: GEO

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Project description:RNA polymerase II (Pol II) transcription initiation starts with the assembly of the preinitiation complex (PIC) on core promoters. The PIC is composed of six general transcription factors (GTFs). The recognition of the core promoter sequences by the TFIID GTF complex is the first step of the PIC assembly. In metazoans, holo-TFIID is composed of the TATA binding protein (TBP) and of 13 TBP associated factors (TAFs). Genetic depletion of different murine TAFs have shown that TAFs such as TAF7 or TAF10, can be either required, or dispensable for Pol II transcription, depending on different cellular contexts. In this report, we depleted TAF7 and/or TAF10 in the same cellular system; either in mesodermal progenitors during mouse development or in mESCs. In these two models, TAF7 depletion leads to a milder phenotype compared to TAF10 depletion. As TAF10 is also a subunit of the transcriptional co-activator Spt-Ada-Gcn5 acetyl transferase (SAGA), we first showed that the difference in phenotype between the Taf7 and Taf10 mutant is not due to the SAGA effect, at least for mESCs. Immunoprecipitations coupled with mass spectrometry analyses from mESCs lysates assembly of holo-TFIID complex is rapidly affected after induction of the depletion. In line with the model of holo-TFIID sequential assembly, TAF10 depletion leads to an early defect with formation of the core-TFIID, while TAF7 depletion results in the formation of a TAF7-less TFIID. Thus, the difference in phenotype severity correlates with the degree of TFIID disassembly. Surprisingly, no major global changes in Pol II transcription could be observed after either TAF7 or TAF10 depletion. Our data suggest that the inducible loss of fully assembled canonical TFIID does not correlate with the lack of global Pol II transcription activity changes suggesting that partially assembled TFIID complexes can participate in Pol II transcription initiation, with only limited effect on Pol II nascent transcription.

Project description:TATA-binding protein (TBP) is central to the regulation of transcription initiation. Recruitment of TBP to target genes can be positively regulated by one of two basal transcription factor complexes: SAGA or TFIID. Negative regulation of TBP promoter association can be performed by Mot1 or the NC2 complex. Recent evidence suggest that Mot1, NC2, and TBP form a DNA-dependent protein complex. Here, we compare the functions of Mot1 and NC2beta during basal and activated transcription using the anchor-away technique for conditional nuclear depletion. Genome-wide expression analysis indicates that both proteins regulate a highly similar set of genes (r2=0.8). Upregulated genes were enriched for SAGA occupancy, while downregulated genes preferred TFIID binding. Mot1p and NC2beta depletion during heat shock resulted in a failure to downregulate gene expression after initial activation, which was accompanied by increased TBP and RNA pol II promoter occupancies. Depletion of Mot1p or NC2beta displayed preferential synthetic lethality with the TBP-interaction module of SAGA. Our results suggest that Mot1 and NC2beta cooperate in vivo to regulate TBP function, and that they are involved in maintaining basal expression levels as well as in resetting gene expression after induction by stress. In this study 3 S. cerevisiae strains were grown with and without addition of rapamycin. For each experimental factor two independent colonies were inoculated in Complete Synthetic Medium (CSM) with 2% glucose. Overnight cultures were diluted to 0.3 OD600 in 50 ml medium and grown to 1 OD600. Cultures were then grown for 60 minutes in the absence or presence of rapamycin at 1ug/ml (LC laboratories). Cells were harvested by centrifugation at 4000 rpm for 3 minutes and were frozen in liquid nitrogen. Amplified cRNA samples were labeled with either cy3 or cy5 and put on microarray together with an oppositely labeled common reference sample consisting of cRNA of untreated wildtype strain.

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Supt3 mutant nascent RNA-seq

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