Context-Dependent Enhancer Selection Confers Alternate Modes of Notch Regulation on argos

Abstract

Wiring between signaling pathways differs according to context, as exemplified by interactions between Notch and EGFR pathways, which are cooperative in some contexts but antagonistic in others. To investigate mechanisms that underlie different modes of cross-talk we have focused on argos, an EGFR pathway regulator in Drosophila which is up-regulated by Notch in adult muscle progenitors but is repressed in the wing. Results show that the alternate modes of cross-talk depend on the engagement of enhancers with opposite regulatory logic, which are selected by context-determining factors. This is likely to be a general mechanism for enabling the wiring between these pathways to switch according to context.