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14-3-3 proteins associate with cdc25 phosphatases

D S Conklin1, K Galaktionov, D Beach

  • 1Howard Hughes Medical Institute, Cold Spring Harbor Laboratory, NY 11724, USA.

Proceedings of the National Academy of Sciences of the United States of America
|August 15, 1995
PubMed

Insights

14-3-3 proteins interact with cdc25 phosphatases, crucial for cell cycle control. This interaction, identified via yeast two-hybrid screening, links cell signaling to cell cycle progression without altering cdc25A phosphatase activity.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • Cdc25 phosphatases are key regulators of cell cycle progression by activating cyclin-dependent kinases.
  • 14-3-3 proteins are a conserved family involved in diverse signal transduction pathways.
  • Previous studies indicated Raf-1 kinase associates with and stimulates cdc25A phosphatase activity.

Purpose of the Study:

  • To identify proteins interacting with human cdc25A and cdc25B phosphatases.
  • To investigate the functional relationship between cdc25 phosphatases and 14-3-3 proteins.
  • To elucidate the role of 14-3-3 proteins in the signaling pathway involving cdc25A and Raf-1.

Main Methods:

  • Yeast two-hybrid screening to identify interacting proteins.
  • In vitro and in vivo interaction assays.
  • Assays to measure phosphatase activity of cdc25A and cdc25A-Raf-1 complex.

Main Results:

  • Two 14-3-3 proteins (epsilon and beta) were identified as interacting partners of cdc25A and cdc25B.
  • Physical interaction between cdc25 and 14-3-3 proteins was confirmed both in vitro and in vivo.
  • 14-3-3 proteins did not affect the phosphatase activity of cdc25A.
  • 14-3-3 proteins did not influence the cdc25A-kinase activity of Raf-1.
  • Evidence suggests 14-3-3 proteins may facilitate the in vivo association of cdc25A with Raf-1.

Conclusions:

  • 14-3-3 proteins physically interact with cdc25 phosphatases.
  • 14-3-3 proteins play a role in linking mitogenic signaling pathways to cell cycle machinery, potentially by mediating the cdc25-Raf-1 interaction.
  • The interaction between 14-3-3 and cdc25 does not directly modulate cdc25 phosphatase activity but influences its association with Raf-1.

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