A simplified dynamic model for the p53-Mdm2 feedback loop

In this paper, a simplified dynamic model for the p53-Mdm2 feedback loop without the time lag effect of transcription is proposed. In the dynamic model, a nonlinear term is introduced to represent the dephosphorylation of the p53 protein. The results show that while the p53 and Mdm2 exhibit single pulse transient responses for the lower environmental stress stimulation, the sustained oscillations are observed for larger environmental stress stimulation. It is concluded that the simplified dynamic model is also able to reproduce the p53 and Mdm2 dynamic behaviors as shown in the experimental results and as predicted by previous complicated models in the literature. And the transcription time delay is dispensable for the p53 sustained oscillations. The results are helpful for understanding p53 dynamics.