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Updated: Jun 12, 2026
Two- and Three-Dimensional Live Cell Imaging of DNA Damage Response Proteins
Published on: September 28, 2012
E2F-1 regulation by an unusual DNA damage-responsive DP partner subunit
L Ingram1, S Munro, A S Coutts
1Laboratory of Cancer Biology, Department of Clinical Pharmacology, University of Oxford, Old Road Campus Research Building, Old Road Campus, off Roosevelt Drive, Oxford, OX3 7DQ, UK.
Abstract:
E2F activity is negatively regulated by retinoblastoma protein (pRb) through binding to the E2F-1 subunit. Within the E2F heterodimer, DP proteins are E2F partner subunits that allow proper cell cycle progression. In contrast to the other DP proteins, the newest member of the family, DP-4, downregulates E2F activity. In this study we report an unexpected role for DP-4 in regulating E2F-1 activity during the DNA damage response. Specifically, DP-4 is induced in DNA-damaged cells, upon which it binds to E2F-1 as a non-DNA-binding E2F-1/DP-4 complex. Consequently, depleting DP-4 in cells re-instates E2F-1 activity that coincides with increased levels of chromatin-bound E2F-1, E2F-1 target gene expression and associated apoptosis. Mutational analysis of DP-4 highlighted a C-terminal region, outside the DNA-binding domain, required for the negative control of E2F-1 activity. Our results define a new pathway, which acts independently of pRb and through a biochemically distinct mechanism, involved in negative regulation of E2F-1 activity.
Insights
DP-4, a novel protein, unexpectedly regulates E2F-1 activity during DNA damage response. This new pathway, independent of pRb, involves DP-4 binding to E2F-1, inhibiting its activity and preventing apoptosis.
Area of Science:
- Molecular Biology
- Cell Cycle Regulation
- DNA Damage Response
Background:
- E2F activity is crucial for cell cycle progression.
- Retinoblastoma protein (pRb) typically inhibits E2F-1 activity.
- DP proteins partner with E2F subunits to modulate activity.
Purpose of the Study:
- To investigate the role of DP-4 in regulating E2F-1 activity.
- To elucidate the mechanism of DP-4's function during DNA damage.
- To identify a novel pathway for E2F-1 regulation.
Main Methods:
- Induction of DP-4 in DNA-damaged cells.
- Analysis of E2F-1/DP-4 complex formation.
- Depletion of DP-4 to assess effects on E2F-1 activity.
- Mutational analysis of DP-4.
Main Results:
- DP-4 is induced upon DNA damage and binds to E2F-1.
- DP-4 forms a non-DNA-binding complex with E2F-1, downregulating its activity.
- DP-4 depletion reactivates E2F-1, leading to increased apoptosis.
- A C-terminal region of DP-4 is essential for inhibiting E2F-1.
Conclusions:
- DP-4 plays an unexpected role in negatively regulating E2F-1 activity during DNA damage.
- A novel pRb-independent pathway for E2F-1 control is identified.
- DP-4 acts via a distinct biochemical mechanism to suppress E2F-1 function.
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