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Centrosomal MPF triggers the mitotic and morphogenetic switches of fission yeast

Agnes Grallert1, Avinash Patel, Victor A Tallada

  • 1CRUK Cell Division Group, Paterson Institute for Cancer Research, Wilmslow Road, Manchester, M20 4BX, UK.

Nature Cell Biology
|December 11, 2012
PubMed

Insights

Local activation of mitosis-promoting factor (MPF) on spindle pole bodies (SPBs) in fission yeast controls Polo kinase activity, dictating cell cycle timing. This SPB-localized MPF and Polo kinase activity are crucial for new cell end growth.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • Mitosis-promoting factor (MPF) activation initiates mitotic commitment in human cells, initially observed on centrosomes.
  • Fission yeast, a model organism, possesses spindle pole bodies (SPBs) analogous to centrosomes.
  • Cell cytokinesis in fission yeast creates a new cell end, with growth initially restricted to the old end.

Purpose of the Study:

  • To investigate the role of local MPF activation on SPBs in fission yeast.
  • To determine the relationship between MPF, Polo kinase, and the timing of mitotic commitment and new end take off (NETO).
  • To elucidate how SPB-localized kinases regulate distinct cell cycle transitions.

Main Methods:

  • Utilized fission yeast as a model system.
  • Investigated MPF and Polo kinase activity at SPBs during the cell cycle.
  • Experimentally manipulated MPF and Polo activity at various cellular locations.
  • Observed the effects of ectopic kinase activation on cell cycle progression and growth.

Main Results:

  • Local MPF activation on G2 phase SPBs promotes Polo kinase activity prior to global MPF activation.
  • This localized control of Polo kinase (Plo1) activity on G2 SPBs dictates the timing of mitotic commitment.
  • MPF and Polo kinase activities are essential for new end take off (NETO), the onset of bipolar growth.
  • Ectopic activation of MPF or Polo at interphase SPBs induced NETO, with MPF's effect requiring Polo.

Conclusions:

  • Local MPF activation on G2 SPBs directs Polo kinase to regulate temporally separated cell cycle events.
  • SPB-localized MPF and Polo kinase play critical roles in controlling both mitotic commitment and the initiation of bipolar growth (NETO).
  • This study reveals a novel mechanism of localized kinase control over distinct cellular processes in fission yeast.

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