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Ser149 is another potential PKA phosphorylation target of Cdc25B in G2/M transition of fertilized mouse eggs

Jianying Xiao1, Chao Liu, Junjie Hou

  • 1Institute of Pathology and Pathopysiology, China Medical University, Shenyang, Liaoning Province 110001, China.

The Journal of Biological Chemistry
|January 8, 2011
PubMed

Insights

Protein Kinase A (PKA) regulates M phase-promoting factor (MPF) by phosphorylating cell division cycle 25 homolog B (Cdc25B). This study identifies Ser(149) as a key PKA site in fertilized mouse eggs, impacting G(2)/M transition and early embryonic development.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Developmental Biology

Background:

  • Protein Kinase A (PKA) is a known negative regulator of M phase-promoting factor (MPF) in mammals.
  • PKA phosphorylates cell division cycle 25 homolog B (Cdc25B), but the precise molecular mechanism is not fully understood.

Purpose of the Study:

  • To identify PKA phosphorylation sites on Cdc25B.
  • To investigate the role of Cdc25B Ser(149) in the G(2)/M transition of fertilized mouse eggs.
  • To elucidate the regulatory role of PKA in early mouse embryonic development.

Main Methods:

  • In vitro LC-MS/MS analysis to identify PKA phosphorylation sites on Cdc25B.
  • Overexpression of Cdc25B wild-type (WT) and mutant forms (S149A, S149D) in fertilized mouse eggs.
  • Analysis of MPF activation, Cdc2-Tyr(15) dephosphorylation, and cell cycle progression.
  • In vivo studies to examine Cdc25B phosphorylation status and subcellular localization during the cell cycle.

Main Results:

  • LC-MS/MS identified Ser(149), Ser(229), and Ser(321) as PKA phosphorylation sites on Cdc25B.
  • Overexpression of Cdc25B-S149A accelerated MPF activation and mitosis by dephosphorylating Cdc2-Tyr(15).
  • Cdc25B-Ser(149) is phosphorylated during G(1)/S phases and dephosphorylated during G(2)/M, regulated by PKA in vivo.
  • Cdc25B translocates from the cytoplasm to the nucleus during the G(2) phase.

Conclusions:

  • Ser(149) is a critical PKA phosphorylation site on Cdc25B regulating G(2)/M transition in fertilized mouse eggs.
  • Cdc25B acts as a direct downstream substrate of PKA, playing a significant role in early mouse embryonic development.

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