The canonical Wg and JNK signaling cascades collaborate to promote both dorsal closure and ventral patterning

Elaboration of the Drosophila body plan depends on a series of cell-identit y decisions and morphogenetic movements regulated by intercellular signals. For example, Jun N-terminal kinase signaling regulates cell fate decisions and morphogenesis during dorsal closure, while Wingless signaling regulate s segmental patterning of the larval cuticle via Armadillo. wingless or arm adillo mutant embryos secrete a lawn of ventral denticles; armadillo mutant s also exhibit dorsal closure defects. We found that mutations in puckered, a phosphatase that antagonizes Jun N-terminal kinase, suppress in a dose-s ensitive manner both the dorsal and ventral armadillo cuticle defects, Furt hermore, we found that activation of the Jun N-terminal kinase signaling pa thway suppresses armadillo-associated defects. Jun N-terminal kinase signal ing promotes dorsal closure, in part, by regulating decapentaplegic express ion in the dorsal epidermis. We demonstrate that Wingless signaling is also required to activate decapentaplegic expression and to coordinate cell sha pe changes during dorsal closure. Together, these results demonstrate that MAP-Kinase and Wingless signaling cooperate in both the dorsal and ventral epidermis, and suggest that Wingless may activate both the Wingless and the Jun N-terminal kinase signaling cascades.