Venkatachalapathy, H.; Yang, Z.; Azarin, S. M.; Sarkar, C. A.; Batchelor, E.

The dynamic expression pattern of the tumor suppressor p53 can have significant cell-to-cell heterogeneity, leading to variability in cellular stress responses and resulting in clinical consequences such as cancer chemoresistance. Using a combination of mathematical modeling, time-lapse fluorescence microscopy, and single-cell tracking, we exploit the oscillatory nature of the p53 response to DNA double-strand break (DSB) induction to reduce cellular heterogeneity by entraining p53 dynamics. Our study demonstrates that oscillatory p53 dynamics can be experimentally entrained over a wider range of DSB frequencies than predicted by an established computational model for this system. Non-intuitively, we determined that recapitulating this increased entrainment range required a modified model with a less robust oscillator and wider steady-state valley on the energy landscape. Further, we show that p53 entrainment can lead to altered expression dynamics of downstream targets responsible for cell fate in a manner dependent on target mRNA stability. Overall, this study exemplifies the potential of externally entraining p53 dynamics to reduce cellular variability and synchronize cell-fate responses to genotoxic agents.