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Yeast endosulfines control entry into quiescence and chronological life span by inhibiting protein phosphatase 2A

Séverine Bontron1, Malika Jaquenoud, Stefania Vaga

  • 1Department of Biology, Division of Biochemistry, University of Fribourg, 1700 Fribourg, Switzerland.

Cell Reports
|January 1, 2013
PubMed

Insights

Nutrient limitation activates Rim15 kinase, which inhibits PP2A(Cdc55) via endosulfines. This preserves Gis1 phosphorylation, promoting gene expression for cellular quiescence and longevity.

Area of Science:

  • Cellular Biology
  • Molecular Biology
  • Biochemistry

Background:

  • TORC1 and PKA kinases regulate eukaryotic cell proliferation.
  • Nutrient limitation in yeast activates Rim15 kinase, initiating quiescence.
  • Endosulfines Igo1/2 link Rim15 to gene expression.

Purpose of the Study:

  • To elucidate the molecular mechanism linking Rim15 to the regulation of quiescence.
  • To identify the role of PP2A(Cdc55) in nutrient-mediated signaling.

Main Methods:

  • Phosphorylation assays
  • Inhibition studies of PP2A(Cdc55)
  • Analysis of Gis1 phosphorylation and gene expression

Main Results:

  • Rim15 directly phosphorylates endosulfines, inhibiting PP2A(Cdc55).
  • PP2A(Cdc55) inhibition maintains Gis1 phosphorylation.
  • This promotes Gis1 recruitment and activation of nutrient-regulated gene transcription.

Conclusions:

  • PP2A(Cdc55) acts as a key inhibitor in the Rim15 signaling pathway.
  • This pathway is crucial for regulating quiescence and chronological lifespan.
  • The findings reveal a novel role for PP2A(Cdc55) in nutrient sensing and longevity.

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