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mik1 and wee1 cooperate in the inhibitory tyrosine phosphorylation of cdc2

K Lundgren1, N Walworth, R Booher

  • 1Howard Hughes Medical Institute, Cold Spring Harbor Laboratory, New York 11724.

Cell
|March 22, 1991
PubMed

Insights

The mik1 and wee1 kinases regulate cell division by controlling cdc2 phosphorylation in S. pombe. Loss of both kinases leads to lethal cell cycle bypass, suggesting they are essential for M phase checkpoints.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Genetics

Background:

  • Wee1 kinase antagonizes Cdc25 phosphatase in regulating cdc2 activity.
  • The precise role of Wee1 in tyrosine phosphorylation of cdc2 remains unclear.
  • Mik1 is a related kinase to Wee1 with an obscure function.

Purpose of the Study:

  • To investigate the role of Mik1 in S. pombe cell cycle regulation.
  • To determine the functional relationship between Mik1 and Wee1.
  • To elucidate the mechanism of cdc2 regulation during M phase.

Main Methods:

  • Construction and analysis of mik1 and wee1 null mutants in S. pombe.
  • Assessment of M phase checkpoints and cell cycle progression.
  • Analysis of cdc2 tyrosine phosphorylation status in various mutant backgrounds.

Main Results:

  • Mik1 acts redundantly with Wee1 in negatively regulating cdc2.
  • A mik1 wee1 double mutant exhibits hypermitotic lethality, bypassing critical M phase checkpoints.
  • Absence of Mik1 and Wee1 leads to rapid dephosphorylation of cdc2 tyrosine.

Conclusions:

  • Mik1 and Wee1 cooperate in the inhibitory tyrosine phosphorylation of cdc2.
  • These kinases are essential for maintaining M phase integrity and checkpoint control.
  • The findings suggest Mik1 and Wee1 are either direct inhibitory kinases or essential activators of the inhibitory kinase for cdc2.

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