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Studying Proteolysis of Cyclin B at the Single Cell Level in Whole Cell Populations
10:54

Studying Proteolysis of Cyclin B at the Single Cell Level in Whole Cell Populations

Published on: September 17, 2012

A non-cycling mitotic cyclin in the naturally synchronous cell cycle of Physarum polycephalum

J W Cho1, H W Sauer

  • 1Department of Biology, Texas A&M University, College Station 77843-3258.

European Journal of Cell Biology
|October 1, 1994
PubMed

Insights

Maturation or mitosis promoting factor (MPF) controls the eukaryotic cell cycle. This study found histone H1 kinase activation during mitosis, but not cyclin B degradation, challenging existing models of cell cycle control.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • The cell cycle in eukaryotic organisms is universally regulated by maturation or mitosis promoting factor (MPF).
  • MPF is a heterodimer of p34cdc2 (catalytic subunit) and mitotic cyclin (regulatory subunit).
  • Cyclin accumulation during interphase and degradation during mitosis are thought to inactivate MPF and facilitate mitotic exit.

Purpose of the Study:

  • To investigate the role of cyclin B degradation in MPF inactivation and cell cycle control during mitosis.
  • To determine if cyclin B levels fluctuate during mitosis in Physarum plasmodium.

Main Methods:

  • Utilized the synchronized mitotic cycle of Physarum plasmodium.
  • Employed p13suc1 Sepharose beads for high-affinity capture of p34cdc2/cyclin B complexes.
  • Used immunological reagents, including anti-cyclin B and anti-PSTAIR antibodies, for detection.

Main Results:

  • Detected transient histone H1 kinase activation during mitosis.
  • Observed no significant fluctuation in cyclin B abundance during mitosis.
  • Demonstrated that cyclin B degradation is not essential for histone H1 kinase inactivation in mitosis.

Conclusions:

  • Cyclin degradation may be involved in later cell cycle events like cytokinesis, G1 phase control, or developmental cell signaling.
  • The inactivation of histone H1 kinase during mitosis is independent of cyclin B degradation.

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