Stochastic Endogenous Replication Stress Causes ATR-Triggered Fluctuations in CDK2 Activity that Dynamically Adjust...

Area of Science:

• Cell Biology
• Molecular Biology
• Genetics

Background:

• Faithful DNA replication is crucial for cell viability and is challenged by replication fork stalling during S phase.
• Replication stress, a common occurrence in cancer cells and after genotoxic insults, further compromises DNA replication fidelity.

Purpose of the Study:

• To investigate the dynamic regulation of DNA replication during S phase.
• To elucidate the role of Cyclin-Dependent Kinase 2 (CDK2) activity in response to replication stress.

Main Methods:

• Live single-cell image analysis was employed to monitor CDK2 activity and DNA synthesis rates throughout S phase.
• Stochastic replication stress events and their impact on CDK2 signaling were analyzed.

Main Results:

• CDK2 activity was found to fluctuate throughout an unperturbed S phase, driven by transient ATR signals from stochastic replication stress.
• Fluctuating CDK2 activity directly correlated with dynamic changes in DNA synthesis rates, linking replication stress to replication dynamics.
• Cells re-entering the cell cycle exhibited increased CDK2 fluctuations and prolonged S phases due to heightened replication stress.

Conclusions:

• CDK2 activity fluctuates dynamically throughout S phase, acting as a key regulator of DNA synthesis rates in response to stochastic replication stress.
• This dynamic control mechanism allows cells to continually adjust DNA replication rates, maintaining fidelity under challenging conditions.
• Understanding CDK2's role in replication stress response offers insights into cancer biology and potential therapeutic strategies.