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- Holmqvist, Per-Henrik, et al.
(author)
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Preferential Genome Targeting of the CBP Co-Activator by Rel and Smad Proteins in Early Drosophila melanogaster Embryos
- 2012
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In: PLOS Genetics. - San Francisco : Public Library of Science (PLoS). - 1553-7390 .- 1553-7404. ; 8:6
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Journal article (peer-reviewed)abstract
- CBP and the related p300 protein are widely used transcriptional co-activators in metazoans that interact with multiple transcription factors. Whether CBP/p300 occupies the genome equally with all factors or preferentially binds together with some factors is not known. We therefore compared Drosophila melanogaster CBP (nejire) ChIP-seq peaks with regions bound by 40 different transcription factors in early embryos, and we found high co-occupancy with the Rel-family protein Dorsal. Dorsal is required for CBP occupancy in the embryo, but only at regions where few other factors are present. CBP peaks in mutant embryos lacking nuclear Dorsal are best correlated with TGF-beta/Dpp-signaling and Smad-protein binding. Differences in CBP occupancy in mutant embryos reflect gene expression changes genome-wide, but CBP also occupies some non-expressed genes. The presence of CBP at silent genes does not result in histone acetylation. We find that Polycomb-repressed H3K27me3 chromatin does not preclude CBP binding, but restricts histone acetylation at CBP-bound genomic sites. We conclude that CBP occupancy in Drosophila embryos preferentially overlaps factors controlling dorsoventral patterning and that CBP binds silent genes without causing histone hyperacetylation.
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| 2. |
- Holmqvist, Per-Henrik, et al.
(author)
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Genomic occupancy of the transcriptional co-activators p300 and CBP.
- 2012
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In: Transcription. - : Informa UK Limited. - 2154-1272 .- 2154-1264. ; 4:1, s. 18-23
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Journal article (peer-reviewed)abstract
- The p300 and CBP co-activators are histone acetylases and central regulators of transcription in metazoans. The genomic occupancy of p300/CBP detected by ChIP-seq experiments can be used to identify transcriptional enhancers. However, studies in Drosophila embryos suggest that there is a preference for some transcription factors in directing p300/CBP to the genome. Although p300/CBP occupancy in general correlates with gene activation, they can also be found at silent genomic regions, which does not result in histone acetylation. Polycomb-mediated H3K27me3 is associated with repression, but does not preclude p300/CBP binding. An antagonism between H3K27ac and H3K27me3 indicates that p300/CBP may be involved in switching between repressed and active chromatin states.
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