DISHEVELLED ACTIVATES JNK AND DISCRIMINATES BETWEEN JNK PATHWAYS IN PLANAR POLARITY AND WINGLESS SIGNALING

Frizzled family proteins have been described as receptors of Wnt signa ling molecules. In Drosophila, the two known Frizzled proteins are ass ociated with distinct developmental processes. Genesis of epithelial p lanar polarity requires Frizzled, whereas Dfz2 affects morphogenesis b y wingless-mediated signaling. Dishevelled is required in both signali ng pathways. Here, we use genetic and overexpression assays to show th at Dishevelled activates JNK cascades. Rescue analysis reveals differe nt protein domain requirements in Dishevelled far the two pathways; th e C-terminal DEP domain is essential to rescue planar polarity defects and induce JNK signaling. Furthermore, the planar polarity-specific d sh(1) allele is mutated in the DEP domain. Our results indicate that d ifferent Wnt/Fz signals activate distinct intracellular pathways, and Dishevelled discriminates among them by distinct domain interactions.