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Inhibitor-2 induced M-phase arrest in Xenopus cycling egg extracts is dependent on MAPK activation

Arian Khandani1, Mahmood Mohtashami, Anne Camirand

  • 1Department of Cell Biology, University of Alberta, Edmonton, Alberta, Canada, T6G 2H7 arian.khandani@sickkids.ca.

Cellular & Molecular Biology Letters
|September 30, 2011
PubMed

Insights

Inhibitor-2 protein triggers M-phase arrest in Xenopus egg extracts, dependent on mitogen-activated protein kinase (MAPK) activity. This study reveals a new link between MAPK and protein phosphatase 1 (PP1) pathways in cell cycle regulation.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • Protein phosphatase 1 (PP1) is crucial for dephosphorylating phosphoproteins during M phase.
  • Inhibitor-2 (Inh-2), a PP1 inhibitor, is known to play a role in regulating PP1 activity.

Purpose of the Study:

  • To investigate the role of Inh-2 in cell cycle regulation.
  • To determine if Inh-2-induced M-phase arrest is dependent on the mitogen-activated protein kinase (MAPK) pathway.
  • To elucidate the mechanism linking PP1 and MAPK pathways during M phase.

Main Methods:

  • Xenopus cycling egg extracts were used to study M-phase arrest.
  • The effect of Inh-2 on M-phase progression was analyzed.
  • MAPK activity was inhibited using PD98059 to assess its role in Inh-2-induced arrest.
  • Phosphorylation of Inh-2 by p90Rsk was investigated.

Main Results:

  • Inhibitor-2 (Inh-2) induces M-phase arrest in Xenopus egg extracts.
  • This M-phase arrest is dependent on mitogen-activated protein kinase (MAPK) activity.
  • Inhibition of MAPK by PD98059 prevents Inh-2-induced M-phase arrest.
  • Phosphorylation of Inh-2 by p90Rsk is not required for its function in inducing M-phase arrest.

Conclusions:

  • Inh-2 induces M-phase arrest through a mechanism that requires MAPK activity.
  • A novel link between the MAPK and PP1 pathways in regulating M phase is suggested.
  • The phosphorylation status of Inh-2 by MAPK is not essential for its role in cell cycle arrest.

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