Negative regulation of Wingless signaling by D-axin, a Drosophila homolog of axin

Wnt/Wingless directs many cell fates during development. Wnt/Wingless signa ling increases the amount of beta-catenin/Armadillo, which in turn activate s gene transcription. Here the Drosophila protein D-Axin was shown to inter act with Armadillo and D-APC. Mutation of d-axin resulted in the accumulati on of cytoplasmic Armadillo and one of the Wingless target gene products, D istal-less. Ectopic expression of d-axin inhibited Wingless signaling. Henc e, D-Axin negatively regulates Wingless signaling by down-regulating the Le vel of Armadillo. These results establish the importance of the Axin family of proteins in Wnt/Wingless signaling in Drosophila.