A plausible model for bimodal p53 switch in DNA damage response.

Area of Science:

• Cellular dynamics
• Molecular biology
• Cancer research

Background:

• p53 acts as a tumor suppressor, with its activity patterns depending on external stimuli.
• Recent studies indicate a role for p53 in cell fate decisions, exhibiting a bimodal switch.
• Theoretical investigations into the mechanisms of bimodal p53 induction are lacking.

Purpose of the Study:

• To investigate the theoretical underpinnings of bimodal p53 induction.
• To explore the role of MDM2-p53 mRNA binding in the p53 switch.
• To model the dynamics of p53 in response to varying levels of cellular damage.

Main Methods:

• Development of a theoretical model to simulate p53 dynamics.
• Analysis of the positive feedback loop involving MDM2 and p53 mRNA.
• Simulation of p53 responses to different levels of DNA damage, including etoposide treatment.

Main Results:

• MDM2-p53 mRNA binding can drive a bimodal p53 switch via an intrinsic positive feedback loop.
• Lower cellular damage resulted in pulsing p53 dynamics, while higher damage led to a monotonic increase.
• Bimodal p53 dynamics are significantly influenced by cellular MDM2 levels and p53/MDM2 ratios, with increased etoposide favoring mono-ubiquitination.

Conclusions:

• The proposed model successfully replicates experimental findings on p53 dynamics.
• MDM2-p53 mRNA binding is a potential mechanism contributing to the bimodal p53 switch.
• The study offers insights into the dynamic mechanisms governing bimodal p53 induction in response to cellular stress.