BLANC - Blanc

Carctérisation fonctionnelle et analyse génomique du complexe histone acétyl-transférase ATAC – GenomATAC

Submission summary

Transcription in eukaryotes is a tightly regulated, multistep process. Gene specific transcriptional activators, several different cofactors, often harbouring chromatin modifying activities, and general transcription factors are necessary to access specific loci in the chromatin to allow precise initiation of RNA polymerase II transcription. Post-translational modifications of histones have been correlated with the involvement of the chromatin in transcription activation or repression. One of the most extensively studied modifications is the acetylation of the highly conserved amino-terminal histone tails. Histone acetyl transferases (HATs) are thought to increase the decompaction of chromatin, which in turn increases the accessibility of factors that promote transcription One of the most appealing questions in eukaryotic transcription is how activators can transmit their signals to the general transcription machinery to stimulate transcription in the context of a highly condensed chromatin environment. Another exciting question from the eukaryotic transcription regulation point of view is how stem cells can regulate their transcription networks to maintain their pluripotency and how these regulatory networks change when stem cells differentiate to various cell types. Stem cells have recently become the focus of intensive research, because they may be used in the future to generate cells and tissues for therapeutic purposes. Since their identification, many studies have been carried on the structure, role and function of different HAT complexes in yeast, however relatively little is know about the role and function of these complexes in metazoans and how these chromatin modifying complexes are involved in maintenance of pluripotency and differentiation. In the previous years we have devoted our efforts to the characterization of the human SAGA-type (GCN5- or PCAF-containing) complexes. However, in the past year others and we have discovered a novel GCN5- or PCAF-containing complex, called ATAC (for Ada two a containing). We hypothesize that the increased complexity of GCN5- or PCAF-containing HAT complexes in metazoans (e.g. SAGA and ATAC complexes), as compared to the yeast, is required for metazoan specific functions such as cell pluripotency and differentiation. To better understand the function of the GCN5- or PCAF-containing HAT complexes in metazoans and begin to answer the above exposed two fundamental questions together, in our present project we propose: -to perform the biochemical and cellular characterization of ATAC complexes in ES cells by using proteomics to identify a) the subunit composition of ATAC (GCN5- or PCAF-containing) b) the ES cell interactome of ATAC (GCN5- or PCAF-containing) c) the post-translational modifications of the identified ATAC subunits -to identify direct ATAC binding sites in the genome of ES and neuronal cells by using chromatin immunoprecipiattion coupled high throughput sequencing (ChIP-seq) and bioinformatics -to identify ATAC target genes and their role in ES cells and differentiation by using knockdown approaches coupled to global transcriptomic analyses -to identify pathways, networks and hubs regulated by the ATAC HAT complex, comparing them to pathways regulated by another HAT complex, SAGA, and understanding their role in cell differentiation by using high throughput and newly developed bioinformatics techniques, tools and platforms. The present project is built on the combined strengths of the partners, including molecular biology, systems biology, genome research and bioinformatics.

Project coordination

The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.


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Beginning and duration of the scientific project: - 0 Months

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