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

Drosophila Armadillo is a multifunctional protein implicated in both cell adhesion, as a catenin, and cell signaling, as part of the Wingless signal transduction pathway. We have generated viable fly stocks with alterations in the level of Armadillo available for signaling. Flies from one stock overexpress Armadillo and, as a result, have increased vein material and bristles in the wings. Flies from the other stock have reduced cytoplasmic Armadillo following overexpression of the intracellular domain of DE-cadherin. These flies display a wing-notching phenotype typical of wingless mutations. Both misexpression phenotypes can be dominantly modified by removing one copy of genes known to encode members of the wingless pathway. Here we describe the identification of further mutations that dominantly modify the Armadillo misexpression phenotypes. These mutations are in genes encoding three different functions: establishment and maintenance of adherens junctions, cell cycle control, and Egfr signaling.