Checkpoints in a yeast differentiation pathway coordinate signaling during hyperosmotic stress

PLoS Genet. 2012 Jan;8(1):e1002437. doi: 10.1371/journal.pgen.1002437. Epub 2012 Jan 5.

Abstract

All eukaryotes have the ability to detect and respond to environmental and hormonal signals. In many cases these signals evoke cellular changes that are incompatible and must therefore be orchestrated by the responding cell. In the yeast Saccharomyces cerevisiae, hyperosmotic stress and mating pheromones initiate signaling cascades that each terminate with a MAP kinase, Hog1 and Fus3, respectively. Despite sharing components, these pathways are initiated by distinct inputs and produce distinct cellular behaviors. To understand how these responses are coordinated, we monitored the pheromone response during hyperosmotic conditions. We show that hyperosmotic stress limits pheromone signaling in at least three ways. First, stress delays the expression of pheromone-induced genes. Second, stress promotes the phosphorylation of a protein kinase, Rck2, and thereby inhibits pheromone-induced protein translation. Third, stress promotes the phosphorylation of a shared pathway component, Ste50, and thereby dampens pheromone-induced MAPK activation. Whereas all three mechanisms are dependent on an increase in osmolarity, only the phosphorylation events require Hog1. These findings reveal how an environmental stress signal is able to postpone responsiveness to a competing differentiation signal, by acting on multiple pathway components, in a coordinated manner.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Gene Expression Regulation, Fungal
  • MAP Kinase Signaling System / genetics*
  • Mitogen-Activated Protein Kinases / genetics
  • Mitogen-Activated Protein Kinases / metabolism*
  • Osmolar Concentration*
  • Pheromones / genetics
  • Pheromones / metabolism*
  • Phosphorylation
  • Protein-Serine-Threonine Kinases / metabolism
  • Saccharomyces cerevisiae / genetics*
  • Saccharomyces cerevisiae / metabolism*
  • Saccharomyces cerevisiae / physiology
  • Saccharomyces cerevisiae Proteins / genetics
  • Saccharomyces cerevisiae Proteins / metabolism*
  • Signal Transduction

Substances

  • Pheromones
  • STE50 protein, S cerevisiae
  • Saccharomyces cerevisiae Proteins
  • RCK2 protein, S cerevisiae
  • Protein-Serine-Threonine Kinases
  • FUS3 protein, S cerevisiae
  • HOG1 protein, S cerevisiae
  • Mitogen-Activated Protein Kinases