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Updated: May 21, 2026

Combining Mitotic Cell Synchronization and High Resolution Confocal Microscopy to Study the Role of Multifunctional Cell Cycle Proteins During Mitosis
08:33

Combining Mitotic Cell Synchronization and High Resolution Confocal Microscopy to Study the Role of Multifunctional Cell Cycle Proteins During Mitosis

Published on: December 5, 2017

The S. pombe cytokinesis NDR kinase Sid2 activates Fin1 NIMA kinase to control mitotic commitment through Pom1/Wee1

Agnes Grallert1, Yvonne Connolly, Duncan L Smith

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

Nature Cell Biology
|June 12, 2012
PubMed

Insights

The fission yeast Sid2-Mob1 kinase, part of the septum initiation network (SIN), regulates mitotic commitment in G2 phase. It activates Fin1 kinase, a transient event crucial for cell cycle timing.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Genetics

Background:

  • Mitotic exit involves reversing phosphorylation and cell division (cytokinesis).
  • The Septum Initiation Network (SIN) in fission yeast controls cytokinesis, unlike the broader Mitotic Exit Network (MEN) in budding yeast.
  • Core SIN-MEN components are thought to function only at mitosis's end.

Purpose of the Study:

  • To investigate potential roles of SIN components beyond mitosis.
  • To explore the function of the NDR kinase Sid2-Mob1 in the cell cycle.
  • To understand the regulation of mitotic commitment timing.

Main Methods:

  • Investigated the fission yeast Septum Initiation Network (SIN).
  • Focused on the NDR kinase Sid2-Mob1 and its interaction with Fin1.
  • Analyzed cell cycle progression and kinase activities in G2 phase.

Main Results:

  • Sid2-Mob1 functions independently of other SIN components in G2 phase.
  • Sid2-Mob1 promotes mitotic commitment by activating the NIMA-related kinase Fin1.
  • Fin1 activation is transient, modulating the Pom1/Cdr1/Cdr2 network's activity towards Wee1.

Conclusions:

  • Fission yeast Sid2-Mob1 has a novel role in regulating mitotic commitment timing during G2 phase.
  • The study reveals a new function for a core SIN component, extending its known role.
  • Fin1 kinase activation by Sid2-Mob1 represents a transient G2 event critical for cell cycle progression.

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