The CDK1 inhibitory kinase MYT1 in DNA damage checkpoint recovery
1Division of Life Science and Center for Cancer Research, Hong Kong University of Science and Technology, Kowloon, Hong Kong.
Abstract:
Inhibition of cyclin-dependent kinase 1 (CDK1) by phosphorylation is a key regulatory mechanism for both the unperturbed cell cycle and the DNA damage checkpoint. Although both WEE1 and MYT1 can phosphorylate CDK1, little is known about the contribution of MYT1. We found that in contrast to WEE1, MYT1 was not important for the normal cell cycle or checkpoint activation. Time-lapse microscopy indicated that MYT1 did, however, have a rate-determining role during checkpoint recovery. Depletion of MYT1 induced precocious mitotic entry when the checkpoint was abrogated with inhibitors of either CHK1 or WEE1, indicating that MYT1 contributes to checkpoint recovery independently of WEE1. The acceleration of checkpoint recovery in MYT1-depleted cells was due to a lowering of threshold for CDK1 activation. The kinase activity of MYT1 was high during checkpoint activation and reduced during checkpoint recovery. Importantly, although depletion of MYT1 alone did not affect long-term cell growth, it potentiated with DNA damage to inhibit cell growth in clonogenic survival and tumor xenograft models. These results reveal the functions of MYT1 in checkpoint recovery and highlight the potential of MYT1 as a target for anti-cancer therapies.
Insights
MYT1 plays a crucial role in cell cycle checkpoint recovery by regulating cyclin-dependent kinase 1 (CDK1) activation. Inhibiting MYT1 enhances checkpoint recovery and shows potential for anti-cancer therapies.
Area of Science:
- Cell Biology
- Molecular Biology
- Cancer Research
Background:
- Cyclin-dependent kinase 1 (CDK1) phosphorylation regulates cell cycle progression and DNA damage checkpoints.
- WEE1 and MYT1 are known kinases that phosphorylate CDK1, but MYT1's specific role is less understood.
Purpose of the Study:
- To elucidate the specific functions of MYT1 in cell cycle regulation and DNA damage response.
- To investigate MYT1's contribution to checkpoint recovery and its potential as a therapeutic target.
Main Methods:
- Time-lapse microscopy to observe cell behavior.
- Depletion of MYT1 using genetic methods.
- Inhibition of CHK1 and WEE1 kinases.
- Assessment of CDK1 activation thresholds.
- Clonogenic survival and tumor xenograft assays.
Main Results:
- MYT1 is not essential for normal cell cycle or checkpoint activation but is critical for checkpoint recovery.
- MYT1 depletion accelerates checkpoint recovery by lowering the threshold for CDK1 activation.
- MYT1 kinase activity is high during checkpoint activation and decreases during recovery.
- MYT1 depletion potentiates DNA damage to inhibit cell growth and survival.
Conclusions:
- MYT1 plays a rate-determining role in cell cycle checkpoint recovery, independent of WEE1.
- MYT1's function in checkpoint recovery suggests its potential as a novel target for anti-cancer drug development.
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