A screen for identifying genes interacting with Armadillo, the Drosophila homolog of beta-catenin

Drosophila Armadillo is a multifunctional protein implicated in both cell a dhesion, as a catenin, and cell signaling, as part of the Wingless signal t ransduction pathway. We have generated viable fly stocks with alterations i n the level of Armadillo available for signaling. Flies from one stock over express Armadillo and, as a result, have increased vein material and bristl es in the wings. Flies from the other stock have reduced cytoplasmic Armadi llo following overexpression of the intracellular domain of DE-cadherin. Th ese flies display a wing-notching phenotype typical of wingless mutations. Both misexpression phenotypes can be dominantly modified by removing one co py of genes known to encode members of the wingless pathway. Here we descri be the identification of further mutations that dominantly modify the Armad illo misexpression phenotypes. These mutations are in genes encoding three different functions: establishment and maintenance of adherens junctions, c ell cycle control, and Egfr signaling.