Rémy Beaujois
*
EA 4479, Laboratoire de Régulation des Signaux de Division, University of Lille1; USR 3078 CNRS, Institut de Recherche Interdisciplinaire, Villeneuve d’Ascq, France.
Franck Riquet
EA 4479, Laboratoire de Régulation des Signaux de Division, University of Lille1; USR 3078 CNRS, Institut de Recherche Interdisciplinaire, Villeneuve d’Ascq, France.
Katia Cailliau
EA 4479, Laboratoire de Régulation des Signaux de Division, University of Lille1, France.
Edith Browaeys-Poly
EA 4479, Laboratoire de Régulation des Signaux de Division, University of Lille1, France.
Christophe Russo
EA 4479, Laboratoire de Régulation des Signaux de Division, University of Lille1; USR 3078 CNRS, Institut de Recherche Interdisciplinaire, Villeneuve d’Ascq, France.
Ralf Blossey
USR 3078 CNRS, Institut de Recherche Interdisciplinaire, Villeneuve d’Ascq, France.
Dorothée Vicogne
USR 3078 CNRS, Institut de Recherche Interdisciplinaire, Villeneuve d’Ascq, France.
Matthieu Marin
EA 4479, Laboratoire de Régulation des Signaux de Division, University of Lille1, France.
Arlette Lescuyer-Rousseau
EA 4479, Laboratoire de Régulation des Signaux de Division, University of Lille1, France.
Jean-Pierre Vilain
EA 4479, Laboratoire de Régulation des Signaux de Division, University of Lille1, France.
Jean-François Bodart
EA 4479, Laboratoire de Régulation des Signaux de Division, University of Lille1; USR 3078 CNRS, Institut de Recherche Interdisciplinaire, Villeneuve d’Ascq, France.
Abstract
The mitogen-activated protein kinase (MAPK) cascade in Xenopus oocytes exhibits an all-or-none, ultrasensitive response, which is believed to result from a positive feed-back loop. Here we describe a context where 1,10-phenanthroline slowly, but strongly, activates MAPK while it impairs protein synthesis in a zincdependent manner, abolishing any feed-back loop. The induced-MAPK response was found to be strongly ultrasensitive. We argue that underlying this behaviour is a regulation motif akin to a feed-forward loop acting in vivo.