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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

The cyclin B2 component of MPF is a substrate for the c-mos(xe) proto-oncogene product

L M Roy1, B Singh, J Gautier

  • 1Department of Pharmacology, University of Colorado School of Medicine, Denver 80262.

Cell
|June 1, 1990
PubMed

Insights

Mos proto-oncogene directly phosphorylates cyclin B2, a key component of maturation-promoting factor (MPF). This finding reveals a novel mechanism for MPF activation during oocyte maturation, involving mos-mediated phosphorylation of cyclin B2.

Area of Science:

  • Cellular and Molecular Biology
  • Developmental Biology
  • Oncogenes

Background:

  • Maturation-promoting factor (MPF) is crucial for oocyte maturation.
  • MPF comprises cyclin B2 complexed with cdc2 kinase.
  • Activation of MPF requires the c-mos proto-oncogene.

Purpose of the Study:

  • To investigate the role of the c-mos proto-oncogene in MPF activation.
  • To determine if mos directly phosphorylates cyclin B2.
  • To elucidate the mechanism of mos-mediated MPF activation.

Main Methods:

  • In vitro phosphorylation assays using immunoprecipitated v-mos and c-mos.
  • Phosphopeptide analysis to compare phosphorylation patterns.
  • Antisense oligonucleotide injection to ablate c-mos(xe) in oocytes.

Main Results:

  • Both viral mos (v-mos) and Xenopus c-mos (c-mos(xe)) directly phosphorylate cyclin B2 in vitro.
  • The phosphorylation pattern by mos is similar to that of cdc2 kinase.
  • Ablation of c-mos(xe) reduced cyclin B2 phosphorylation in oocyte extracts by 40%.

Conclusions:

  • The c-mos proto-oncogene directly phosphorylates cyclin B2.
  • Mos-mediated phosphorylation of cyclin B2 is a key step in MPF activation during oocyte maturation.
  • This study reveals a novel mechanism for MPF activation involving direct phosphorylation of the cyclin component by mos.

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