DWnt4 and wingless elicit similar cellular responses during imaginal development

Wnt genes encode evolutionarily conserved secreted proteins that provide cr itical functions during development. Although Wnt proteins share highly con served features, they also show sequence divergence, which almost certainly contributes to the variety of their signaling activities. We previously re ported that DWnt4 and wingless (wg), two divergent clustered Wnt genes, can have either antagonist or distinct functions during Drosophila embryogenes is. Here we provide evidence that both genes can elicit similar cellular re sponses during imaginal development. Ectopic expression of DWnt4 along the anterior/posterior (A/P) boundary of imaginal discs alters morphogenesis of adult appendages. In the wing disc, DWnt4 phenocopies ectopic Wg activity by inducing notum to wing transformation, suggesting similar signaling capa bilities of both molecules. In support of this, we demonstrate that DWnt4 c an rescue wg loss-of-function phenotypes in the antenna and haltere and is able to substitute for Wg in wing field specification. We also show that bo th genes are transcribed in overlapping domains in imaginal discs, suggesti ng that DWnt4: may cooperate with wg during limb patterning, (C) 2001 Acade mic Press.