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Genomic occupancy of the transcriptional co-activators p300 and CBP.

Holmqvist PH, Mannervik M - Transcription (2012)

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: The Wenner-Gren Institute, Developmental Biology, Stockholm University, Arrheniuslaboratories E3, SE-106 91 Stockholm, Sweden.

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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Figure 1. (A) Genes that are silenced by Polycomb-mediated H3K27me3 (K27me) can be occupied by p300/CBP. Association of p300/CBP with silent or poised transcriptional enhancers (with or without H3K27me3) does not result in histone acetylation. (B) At active genes, p300/CBP can acetylate histones on H3K27 (K27ac) and H3K18 (not shown), acetylate transcription factors (Ac), function as a scaffolds for recruiting other proteins, or help establish a preinitiation complex by interactions with TFIIB and hypophosphorylated RNA polymerase II.
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Figure 1: Figure 1. (A) Genes that are silenced by Polycomb-mediated H3K27me3 (K27me) can be occupied by p300/CBP. Association of p300/CBP with silent or poised transcriptional enhancers (with or without H3K27me3) does not result in histone acetylation. (B) At active genes, p300/CBP can acetylate histones on H3K27 (K27ac) and H3K18 (not shown), acetylate transcription factors (Ac), function as a scaffolds for recruiting other proteins, or help establish a preinitiation complex by interactions with TFIIB and hypophosphorylated RNA polymerase II.

Mentions: As well as the enzymatic HAT domain, p300 and CBP contain three cysteine-histidine-rich domains (CH1, CH2 and CH3), a KIX-domain, a steroid receptor co-activator interaction domain (SID) and a bromodomain. These serve as protein-protein interaction domains, where the bromodomain recognizes acetyl-lysine in histones and other proteins.9 The mechanisms by which these co-activators facilitate gene activation by transcription factors are not entirely understood. It may involve the adaptor function to bridge transcription factors with basal factors, leading to recruitment of RNA polymerase II, a scaffolding function to facilitate protein-protein and protein-DNA interactions, or involve their intrinsic acetyltransferase activity (Fig. 1B). Most likely, the activity of p300/CBP that is most important for transcription activation is going to vary from gene to gene and/or cellular conditions, or may function together as a means to accommodate multiple transcriptional inputs into a network of activation.


Genomic occupancy of the transcriptional co-activators p300 and CBP.

Holmqvist PH, Mannervik M - Transcription (2012)

Figure 1. (A) Genes that are silenced by Polycomb-mediated H3K27me3 (K27me) can be occupied by p300/CBP. Association of p300/CBP with silent or poised transcriptional enhancers (with or without H3K27me3) does not result in histone acetylation. (B) At active genes, p300/CBP can acetylate histones on H3K27 (K27ac) and H3K18 (not shown), acetylate transcription factors (Ac), function as a scaffolds for recruiting other proteins, or help establish a preinitiation complex by interactions with TFIIB and hypophosphorylated RNA polymerase II.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3644037&req=5

Figure 1: Figure 1. (A) Genes that are silenced by Polycomb-mediated H3K27me3 (K27me) can be occupied by p300/CBP. Association of p300/CBP with silent or poised transcriptional enhancers (with or without H3K27me3) does not result in histone acetylation. (B) At active genes, p300/CBP can acetylate histones on H3K27 (K27ac) and H3K18 (not shown), acetylate transcription factors (Ac), function as a scaffolds for recruiting other proteins, or help establish a preinitiation complex by interactions with TFIIB and hypophosphorylated RNA polymerase II.
Mentions: As well as the enzymatic HAT domain, p300 and CBP contain three cysteine-histidine-rich domains (CH1, CH2 and CH3), a KIX-domain, a steroid receptor co-activator interaction domain (SID) and a bromodomain. These serve as protein-protein interaction domains, where the bromodomain recognizes acetyl-lysine in histones and other proteins.9 The mechanisms by which these co-activators facilitate gene activation by transcription factors are not entirely understood. It may involve the adaptor function to bridge transcription factors with basal factors, leading to recruitment of RNA polymerase II, a scaffolding function to facilitate protein-protein and protein-DNA interactions, or involve their intrinsic acetyltransferase activity (Fig. 1B). Most likely, the activity of p300/CBP that is most important for transcription activation is going to vary from gene to gene and/or cellular conditions, or may function together as a means to accommodate multiple transcriptional inputs into a network of activation.

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: The Wenner-Gren Institute, Developmental Biology, Stockholm University, Arrheniuslaboratories E3, SE-106 91 Stockholm, Sweden.

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.

Show MeSH