SCHNURRI IS REQUIRED FOR DROSOPHILA DPP SIGNALING AND ENCODES A ZINC-FINGER PROTEIN SIMILAR TO THE MAMMALIAN TRANSCRIPTION FACTOR PRDII-BF1

Cytokines of the TGF beta superfamily regulate many aspects of cellula r function by activating receptor complexes consisting of two distantl y related serine/threonine kinases. Previous studies have indicated th at Drosophila dpp uses similar signaling complexes and strictly requir es the punt and thick veins receptors to transduce the signal across t he membrane. Here, we show that the schnurri (shn) gene is required fo r many aspects of dpp signaling, Genetic epistasis experiments indicat e that shn functions downstream of the dpp signal and its receptors. T he shn gene encodes a large protein similar to a family of mammalian z inc finger transcription factors. The shn protein might therefore act as a nuclear target in the dpp signaling pathway directly regulating t he expression of dpp-responsive genes.