THE DORSOVENTRAL REGULATORY GENE CASSETTE SPATZLE TOLL/CACTUS CONTROLS THE POTENT ANTIFUNGAL RESPONSE IN DROSOPHILA ADULTS/

The cytokine-induced activation cascade of NF-KB in mammals and the ac tivation of the morphogen dorsal in Drosophila embryos show striking s tructural and functional similarities (Toll/IL-1, Cactus/1-kappa B, an d dorsal/NF-kappa B). Here we demonstrate that these parallels extend to the immune response of Drosophila. In particular, the intracellular components of the dorsoventral signaling pathway (except for dorsal) and the extracellular Toll ligand, spatzle, control expression of the antifungal peptide gene drosomycin in adults. We also show that mutati ons in the Toll signaling pathway dramatically reduce survival after f ungal infection. Antibacterial genes are induced either by a distinct pathway involving the immune deficiency gene (imd) or by combined acti vation of both imd and dorsoventral pathways.