CBP/p300 double null cells reveal effect of coactivator level and diversity on CREB transactivation

Abstract

It remains uncertain how the DNA sequence of mammalian genes influences the transcriptional response to extracellular signals. Here, we show that the number of CREB-binding sites (CREs) affects whether the related histone acetyltransferases (HATs) CREB-binding protein (CBP) and p300 are required for endogenous gene transcription. Fibroblasts with both CBP and p300 knocked-out had strongly attenuated histone H4 acetylation at CREBtarget genes in response to cyclic-AMP, yet transcription was not uniformly inhibited. Interestingly, dependence on CBP/p300 was often different between reporter plasmids and endogenous genes. Transcription in the absence of CBP/p300 correlated with endogenous genes having more CREs, more bound CREB, and more CRTC2 (a non-HAT coactivator of CREB). Indeed, CRTC2 rescued cAMP-inducible expression for certain genes in CBP/p300 null cells and contributed to the CBP/p300-independent expression of other targets. Thus, endogenous genes with a greater local concentration and diversity of coactivators tend to have more resilient-inducible expression. This model suggests how gene expression patterns could be tuned by altering coactivator availability rather than by changing signal input or transcription factor levels.

Ablation of CBP in Forebrain Principal Neurons Causes Modest Memory and Transcriptional Defects and a Dramatic Reduction of Histone Acetylation But Does Not Affect Cell Viability

“…Our results also indicate that CBP is not an essential coactivator for the induction of the IEGs analyzed in this work, despite the fact that the promoters of these genes contain the DNA binding motifs for the binding of activity-regulated transcription factors known to interact with CBP. This conclusion challenges the proposed, but still unconfirmed, critical role of CBP and activity-driven histone acetylation in memory-related transcription, but it is in good agreement with previous studies in cbp ϩ/Ϫ mice after kainate-induced seizures (Alarcó n et al, 2004) and with recent observations in primary mouse embryonic fibroblasts, demonstrating that the elimination of both CBP and p300 does not prevent the induction of IEGs by forskolin (Kasper et al, 2010).…”

Crebbp loss cooperates with Bcl2 overexpression to promote lymphoma in mice

“…This is consistent with prior observations that show that Crebbpdriven epigenetic changes show a high level of redundancy with those that are driven by Ep300, that epigenetic changes are context dependent, and that nonhistone targets may be central for the role of Crebbp in vivo. [37][38][39][40] We found some evidence for an enrichment of genes with B-cell-specific enhancer elements 35 among our differentially expressed genes, but confirmation of a role of distant regulatory elements needs to be performed with methods that capture the 3-dimensional conformation of the genome, such as Hi-C. 41 We observed significant changes in H3K18Ac in B cells with biallelic inactivation of Crebbp, which primarily localized to intragenic regions. These regions of altered H3K18Ac had a significant overrepresentation of DNA sequences that possessed the Myc binding site.…”

Dynamic acetylation of all lysine-4 trimethylated histone H3 is evolutionarily conserved and mediated by p300/CBP

“…2), This suggests that the enzyme responsible, p300/CBP, targets specific H3 tails but no specific lysine. In p300/CBP doubleknockout mouse fibroblasts, forskolin-induced acetylation of lysine 5, 8, 12, and 16 of histone H4 at c-fos is inhibited (29), further suggesting no specific targeting of residues. A high level of acetylation is insufficient for efficient gene expression in vivo; treatment of cells with TSA enhances acetylation ( Fig.…”

“…They interact with many transcription factors and coactivators, initially suggesting a structural role in promoter complexes (reviewed in ref. 28); p300 and CBP have been localized to c-fos and c-jun by ChIP (18,29) and through interactions with other proteins (30)(31)(32). A purely structural role was challenged following discovery of their acetyltransferase activity (33,34) with the catalytic domain required for transcription from chromatinized promoter constructs in vitro and in vivo (35,36).…”