Severe Osmotic shock triggers a non-linear slowdown of signaling events due to increased molecular crowding
mardi 3 avril 2012 - 11:30-13:30
Chercheur CNRS "Laboratoire Matière et Systèmes Complexes" Université Paris-Diderot
Lieu : Salle de Conférences Pierre Schaeffer Bâtiment 409
Maintenance of water balance is fundamental for life. Cells have developed signaling pathways and transcriptional responses to cope with sudden, potentially lethal, variations of their volume. In particular, hyper osmotic stress mechanically leads to cell shrinkage and eventually molecular crowding. Such increase in protein concentration has been proposed as a modifier of the rates of biochemical reactions. Here, we show that applying severe hyper osmotic shock slows down the functioning of several, unrelated, signaling pathways in yeast. The activity of key signaling proteins involved in osmotic adaptation (Hog1p), the general stress response (Msn2p), the oxidative response (Yap1) and calcium signaling (Crz1p) were all drastically slowed down when stimulated in presence of a severe hyper osmotic shock. All cascades functioning were immediately recovered upon cell volume restoration. Larger cell shrinkage leads to slower signaling dynamics, as expected from colloidal phase transition. We anticipate that this is a very general result which shed lights on the importance of cell volume regulation in cell signaling dynamics.
Contact : Michel JACQUET