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Mol. Cell. Biol., 10 1996, 5888-5895, Vol 16, No. 10
TS Sorensen, R Girling, CW Lee, J Gannon, LR Bandara and NB La Thangue
The cellular transcription factor DRTF1/E2F and the tumor suppressor
protein p53 play important roles in controlling early cell cycle events.
DRTF1/E2F is believed to coordinate and integrate the transcription of cell
cycle-regulating genes, for example, those involved in DNA synthesis, with
the activity of regulatory proteins, such as the retinoblastoma tumor
suppressor gene product (pRb), which modulate its transcriptional activity.
In contrast, p53 is thought to monitor the integrity of chromosomal DNA and
when appropriate interfere with cell cycle progression, for example, in
response to DNA damage. Generic DRTF1/E2F DNA binding activity and
transcriptional activation arise when members of two distinct families of
proteins, such as DP-1 and E2F-1, interact as DP/E2F heterodimers. In many
cell types, DP-1 is a widespread component of DRTF1/E2F DNA binding
activity which when expressed at high levels oncogenically transforms
embryonic fibroblasts. Here, we document an association between DP-1 and
p53 and demonstrate its presence in mammalian cell extracts. In vitro p53
interacts with an immunochemically distinct form of DP-1 and in vivo can
regulate transcription driven by the DP-1/E2F-1 heterodimer. At the
biochemical level, p53 competes with E2F-1 for DP-1, with a consequent
reduction in DNA binding activity. Mutational analysis defines within DP-1
a C-terminal region required for the interaction with p53 and within p53 an
N-terminal region distinct from that required to bind to MDM2. Our results
establish DRTF1/E2F as a common cellular target in growth control mediated
through the activities of pRb and p53 and suggest an alternative mechanism
through which p53 may regulate cellular proliferation.
Copyright © 1996, American Society for Microbiology
Functional interaction between DP-1 and p53
Laboratory of Eukaryotic Molecular Genetics, MRC National Institute for Medical Research, London, United Kingdom.
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