## Abstract

We develop a mathematical model to study the immediate effect of low-dose radiation on the G2 checkpoint and the G2/M transition of the cell cycle via a radiation pathway (the ATM–Chk2 pathway) of an individual mammalian cell. The model consists of a system of nonlinear differential equations describing the dynamics of a network of regulatory proteins that play key roles in the G2/M transition, cell cycle oscillations, and the radiation pathway. We simulate the application of a single pulse of low-dose radiation at different intensities (∼ 0–0.4 Gy) and times during the latter part of the G2-phase. We use bifurcation analysis to characterize the effect of radiation on the G2/M transition via the ATM–Chk2 pathway. We show that radiation between 0.1 and 0.3 Gy can delay the G2/M transition, and radiation higher than 0.3 Gy can fully activate the G2 checkpoint. Also, our results show that radiation can be low enough to neither delay the G2/M transition nor activate the G2 checkpoint (∼ 0.1 Gy). Our model supports the idea that the cell response to radiation during G2-phase explains hyper-radiosensitivity and increased radioresistance (HRS/IRR) observed at low dose.

Original language | English |
---|---|

Pages (from-to) | 3998-4021 |

Number of pages | 24 |

Journal | Bulletin of Mathematical Biology |

Volume | 81 |

Issue number | 10 |

DOIs | |

Publication status | Published - 1 Oct. 2019 |

## Keywords

- ATM
- Cell cycle modelling
- Cell physiology
- Chk2
- G2 checkpoint
- G2/M transition
- HRS
- IRR
- Ionizing radiation
- Radiation pathway
- Regulatory dynamics