Signaling specificity by frizzled receptors in Drosophila

Wnt-Frizzled (Fz) signaling pathways play recurring important roles during the development and homeostasis of vertebrates and invertebrates. Fz recept ors can signal through beta-catenin-dependent and -independent pathways. In Drosophila, Fr and Fz2 are redundant receptors for Wg. In addition, Fz con veys signals through a distinct pathway to organize planar polarization of epithelial structures. We demonstrate that the cytoplasmic sequences of Fz2 and Fz preferentially activate the beta-catenin and planar polarity cascad e, respectively. Both receptors activate either pathway, but with different efficiencies. Intrinsic differences in signaling efficiency in closely rel ated receptors might be a general mechanism for generating signaling specif icity in vivo.