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Experimental Approaches to Study Mitochondrial Localization and Function of a Nuclear Cell Cycle Kinase, Cdk1
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Experimental Approaches to Study Mitochondrial Localization and Function of a Nuclear Cell Cycle Kinase, Cdk1

Published on: February 25, 2016

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Cell size homeostasis is maintained by CDK4-dependent activation of p38 MAPK

Ceryl Tan1, Miriam B Ginzberg2, Rachel Webster3

  • 1Department of Molecular Genetics, University of Toronto, Toronto, ON M5G 1A8, Canada; Cell Biology, The Hospital for Sick Children, Toronto, ON M5G 0A4, Canada.

Developmental Cell
|May 22, 2021
PubMed

Insights

Cell size checkpoints ensure cells reach a target size before division. This study reveals Cyclin-Dependent Kinase 4 (CDK4) activity determines the specific target size by regulating the p38 MAPK pathway.

Area of Science:

  • Cell biology
  • Molecular biology
  • Cell cycle regulation

Background:

  • Cell growth is regulated by signaling molecules, but the mechanisms determining target cell size are unclear.
  • Cell size checkpoints are crucial, halting cell cycle progression in cells below a critical size.
  • A previously identified p38 MAPK-dependent checkpoint prevents cell cycle entry in small cells.

Purpose of the Study:

  • To elucidate the regulatory mechanism determining the specific target cell size.
  • To investigate the role of CDK4 activity in cell size control.
  • To understand how p38 MAPK and CDK4 cooperate in setting cell size thresholds.

Main Methods:

  • Cell-based assays to monitor cell cycle progression.
  • Biochemical analyses to assess protein activity (p38 MAPK, CDK4).
  • Genetic manipulation to alter CDK4 activity levels.

Main Results:

  • CDK4 activity was found to dictate the threshold for p38 MAPK inactivation.
  • Specific CDK4 activity levels are required for cells to transition through the cell cycle.
  • A model is proposed where p38 MAPK and CDK4 function as a size-sensing thermostat.

Conclusions:

  • CDK4 activity is a key determinant of the target cell size.
  • The interplay between p38 MAPK and CDK4 provides a sophisticated mechanism for cell size regulation.
  • This thermostat-like mechanism ensures cells achieve appropriate size before division.
Keywords:
CDK4cell growthcell sizecell size checkpointcell size homeostasiscell size regulationcritical sizecyclin D1p38 MAPKtarget size

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