title: Checkpoints in a yeast differentiation pathway coordinate signaling during hyperosmotic stress.
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.
authors.affiliation: Department of Pharmacology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America.
authors.forename: Michal J
authors.initials: MJ
authors.lastname: Nagiec
authors.forename: Henrik G
authors.initials: HG
authors.lastname: Dohlman
mesh_terms: D015966:Gene Expression Regulation, Fungal; D020935:MAP Kinase Signaling System / Q000235:genetics*; D020928:Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism*; D009994:Osmolar Concentration; D010675:Pheromones / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism* / Q000502:physiology; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction
chemical_list: D010675:Pheromones; C079506:STE50 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; C407464:RCK2 protein, S cerevisiae; D017346:Protein Serine-Threonine Kinases; C075580:FUS3 protein, S cerevisiae; C088589:HOG1 protein, S cerevisiae; D020928:Mitogen-Activated Protein Kinases