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Published on: February 16, 2015

Restraint of apoptosis during mitosis through interdomain phosphorylation of caspase-2

Joshua L Andersen1, Carrie E Johnson, Christopher D Freel

  • 1Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC 27710, USA.

The EMBO Journal
|September 5, 2009
PubMed

Insights

The mitosis-promoting kinase cdk1-cyclin B1 prevents apoptosis by phosphorylating caspase-2 at Ser 340, inhibiting its activation. This phosphorylation is crucial for preventing cell death during mitosis.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Apoptosis Research

Background:

  • Caspase-2 is an apoptotic initiator involved in various cell death pathways.
  • Mitotic catastrophe and oocyte death are linked to caspase-2 activity.
  • The role of cell cycle regulators in apoptosis suppression is not fully understood.

Purpose of the Study:

  • To investigate the mechanism by which cdk1-cyclin B1 suppresses apoptosis.
  • To determine if caspase-2 is a direct target of cdk1-cyclin B1 during mitosis.
  • To elucidate the role of caspase-2 phosphorylation in preventing cell death during cell division.

Main Methods:

  • Western blotting to detect protein phosphorylation.
  • Immunoprecipitation to study protein interactions.
  • Site-directed mutagenesis to create non-phosphorylatable caspase-2 mutants (S340A).
  • Cell culture and treatment with nocodazole to induce mitotic arrest.
  • Analysis of apoptosis and mitotic catastrophe in cells expressing wild-type and mutant caspase-2.

Main Results:

  • Cdk1-cyclin B1 phosphorylates caspase-2 at Ser 340, preventing its activation.
  • Phosphorylation at Ser 340 inhibits caspase-2 during mitosis.
  • The non-phosphorylatable S340A caspase-2 mutant abrogated mitotic suppression of apoptosis.
  • Cells expressing S340A caspase-2 exhibited increased mitotic catastrophe upon nocodazole treatment.
  • Phosphatase 1 dephosphorylated S340, and its interaction with caspase-2 was lost during mitosis.

Conclusions:

  • Mitosis-promoting kinase cdk1-cyclin B1 suppresses apoptosis by inhibitory phosphorylation of caspase-2 at Ser 340.
  • This phosphorylation event prevents caspase-2 activation and subsequent cell death during mitosis.
  • Overcoming cdk1-cyclin B1 activity is necessary for caspase-2-mediated apoptosis during mitotic arrest.

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