Notch and Wingless Signals Collide

摘要

During development, the identities of many cells are determined by signals produced by adjacent or distant tissues. Cells often receive several signals simultaneously and must integrate them in order to take on the correct fate. Although genetic experiments can pro/ide strong evidence for interactions among signaling pathways, whether such interactions are direct or indirect can be difficult to determine by genetics alone. In this issue, Axelrod and co-workers use both genetic and molecular techniques used to examine the interaction between the Notch (N) and wingless (Wg) signaling pathways in Drosophila (1). They show genetically that the two pathways can be mutually inhibitory and suggest that at least some of this inhibition is due to a direct physical interaction between Dishevelled (Dsh), a cytoplasmic protein required for reception of the Wg signal, and the in-tracellular COOH-terminus of the N protein.