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Dynamics of the p53-Mdm2 feedback loop in individual cells
Galit Lahav1, Nitzan Rosenfeld, Alex Sigal
1Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 76100, Israel.
Nature Genetics
|January 20, 2004
Summary
The tumor suppressor p53 protein exhibits pulsed behavior in individual cells following DNA damage. The number of p53 pulses increases with damage, suggesting a digital clock mechanism.
Area of Science:
- Molecular Biology
- Cell Biology
- Biophysics
Background:
- The tumor suppressor p53 protein is crucial for cellular response to DNA damage.
- Traditional studies average cellular behavior, potentially obscuring individual cell dynamics.
- Understanding p53 dynamics is key to comprehending cellular stress responses.
Purpose of the Study:
- To investigate the dynamic behavior of p53 and its regulator Mdm2 in individual living cells.
- To characterize the pulsing behavior of p53 in response to DNA damage.
- To explore the role of the p53-Mdm2 feedback loop in cellular signaling.
Main Methods:
- Utilized functional p53-CFP and Mdm2-YFP fusion proteins.
- Employed time-lapse fluorescence microscopy for real-time observation.
- Tracked p53 and Mdm2 dynamics at the single-cell level.
Main Results:
- Observed p53 expression in discrete pulses after DNA damage.
- Found that genetically identical cells displayed variable numbers of p53 pulses.
- Demonstrated that pulse number, but not height or duration, correlated with DNA damage levels.
Conclusions:
- The p53-Mdm2 feedback loop functions as a 'digital' clock.
- This system releases timed p53 quanta in response to DNA damage.
- The approach enables studying other dynamic signaling systems in single cells.
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