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Pin1 stabilizes Emi1 during G2 phase by preventing its association with SCF(betatrcp)

Cyril Bernis1, Suzanne Vigneron, Andrew Burgess

  • 1Centre de Recherche de Biochimie Macromoléculaire, CNRS FRE 2593, 1919 Route de Mende, 34293 Montpellier cedex 5, France.

EMBO Reports
|December 13, 2006
PubMed

Insights

Pin1 stabilizes early mitotic inhibitor 1 (Emi1) by preventing its degradation during G2 phase. This Pin1-dependent stabilization of Emi1 is crucial for cell cycle progression into S and M phases.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • Early mitotic inhibitor 1 (Emi1) is essential for initiating S and M phases by promoting cyclin A and cyclin B accumulation.
  • Emi1 degradation is typically mediated by SCF(beta-TrCP) and cyclin A/cdk, yet Emi1 remains stable during G2 when these factors are active.

Purpose of the Study:

  • To identify the mechanism stabilizing Emi1 during G2 phase.
  • To elucidate the role of Pin1 in regulating Emi1 stability and cell cycle progression.

Main Methods:

  • Investigated Emi1-Pin1 interactions in vitro and in vivo.
  • Utilized XL2 cells to study Emi1-Pin1 binding during G2 phase.
  • Examined the effect of Pin1 on Emi1 association with SCF(beta-TrCP).

Main Results:

  • Identified Pin1 as a novel regulator that stabilizes Emi1.
  • Demonstrated that Pin1 binds to Emi1 in an isomerization-dependent manner.
  • Showed that Pin1 binding prevents Emi1's association with SCF(beta-TrCP), thereby inhibiting its degradation during G2.
  • Confirmed Emi1-Pin1 interaction in vivo during G2 phase.

Conclusions:

  • Pin1 stabilizes Emi1 during G2 phase by preventing its degradation.
  • Pin1-dependent Emi1 stabilization is critical for the accumulation of cyclin A and cyclin B.
  • This mechanism facilitates entry into S and M phases of the cell cycle.

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