DACHSOUS ENCODES A MEMBER OF THE CADHERIN SUPERFAMILY THAT CONTROLS IMAGINAL DISC MORPHOGENESIS IN DROSOPHILA

Mutations in the dachsous gene of Drosophila lead to striking defects in the morphogenesis of the thorax, legs, and wings. The dachsous gene has been cloned and shown to encode a huge transmembrane protein that is a member of the cadherin superfamily, similar to the fat gene repo rted previously. Both the Dachsous and Fat proteins contain large tand em arrays of cadherin domains-27 and 34, respectively-as compared with 4 cadherin domains in classic vertebrate cadherins. In addition, Dach sous and Eat each has a cytoplasmic domain with sequence similarity to the cytoplasmic beta-catenin-binding domain of classic vertebrate cad herins. The dachsous gene is expressed in the ectoderm of embryos, whe reas its expression in larvae is restricted to imaginal discs and spec ific regions of the brain. The phenotypes of, and genetic interactions between dachsous and fat are consistent with a model in which cell pr oliferation and morphogenesis of imaginal structures depends on the co upled equilibria between homo- and heterophilic interactions of the Da chsous and Fat cadherin proteins.