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The CBP co-activator stimulates E2F1/DP1 activity
D Trouche1, A Cook, T Kouzarides
1Wellcome/CRC Institute and Department of Pathology, University of Cambridge, UK.
Nucleic Acids Research
|November 1, 1996
Summary
The CBP protein directly interacts with E2F1/DP1, acting as a coactivator to enhance its gene activation capacity. This interaction is crucial for cell cycle regulation and suggests a shared binding motif with E1A.
Area of Science:
- Molecular Biology
- Cell Cycle Regulation
- Transcription Factor Function
Background:
- E2F1/DP1 transcription factors regulate genes essential for S phase progression.
- Retinoblastoma protein (RB) represses E2F1/DP1 activity during G1 phase by binding to its activation domain.
- E2F1 activation domain shares similarities with E1A(12S) N-terminal domain, a binding site for RB and CBP.
Purpose of the Study:
- To investigate the interaction between CBP and E2F1/DP1.
- To determine if CBP influences E2F1/DP1 transcriptional activation capacity.
- To elucidate the role of CBP in E2F1-mediated gene regulation.
Main Methods:
- In vitro and in vivo binding assays to detect CBP-E2F1 interaction.
- Site-directed mutagenesis of the E2F1 activation domain to assess CBP binding and transcriptional activity.
- Squelching experiments using E1A N-terminus as a competitor.
Main Results:
- CBP directly contacts the E2F1 activation domain both in vitro and in vivo.
- Deletion of specific residues in E2F1 activation domain impairs CBP binding and coactivation.
- E1A N-terminus competes for CBP binding, indicating a shared motif recognition.
Conclusions:
- CBP functions as a coactivator for E2F1/DP1, enhancing its transcriptional activity.
- CBP recognizes a motif in E2F1 similar to that in E1A.
- The interplay between RB and CBP pathways regulates E2F1 activity, contributing to E1A's biological functions.