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Published on: April 3, 2026
Polo-like kinase 3 is required for entry into S phase
Wendy C Zimmerman1, Raymond L Erikson
1Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA.
Summary
Polo-like kinase 3 (Plk3) is crucial for cell cycle progression, specifically regulating the G1/S phase transition. Depleting Plk3 prevents cells from entering the S phase and re-entering the cell cycle after quiescence.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Polo-like kinase 1 (Plk1) regulates mitosis.
- Plk2 and Plk3 are less understood mammalian polo-like kinase family members.
- Plk3 was initially identified as an immediate early gene.
Purpose of the Study:
- To investigate the function and cell cycle regulation of Plk3.
- To determine Plk3's role in cell cycle transitions.
- To elucidate the molecular mechanisms underlying Plk3's function.
Main Methods:
- Localization studies to determine Plk3's cellular compartment.
- Cell cycle analysis of Plk3 protein levels.
- Lentiviral delivery of Plk3-interfering RNA to deplete Plk3.
- Assessment of cyclin E expression and cell cycle entry into S phase.
- Investigation of Plk3 interaction with Cdc25A.
Main Results:
- Plk3 localizes to the nucleolus.
- Plk3 protein levels are cell cycle-regulated, peaking in the G1 phase.
- Plk3 depletion inhibits cyclin E expression and entry into S phase.
- Plk3 depletion leads to cell quiescence.
- Plk3 depletion attenuates cyclin E expression, suggesting interaction with Cdc25A.
Conclusions:
- Plk3 plays a critical role in regulating the G1/S phase transition.
- Plk3 is essential for re-entry into the cell cycle from quiescence.
- Plk3 may regulate S phase entry partly through interaction with Cdc25A.
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