FUNCTIONAL-ANALYSIS AND REGULATION OF NUCLEAR IMPORT OF DORSAL DURINGTHE IMMUNE-RESPONSE IN DROSOPHILA

In addition to its function in embryonic development, the NF-kappa B/r el-related gene dorsal (dl) of Drosophila is expressed in larval and a dult fat body where its RNA expression is enhanced upon injury. Injury also leads to a rapid nuclear translocation of dl from the cytoplasm in fat body cells. Here we present data which strongly suggest that th e nuclear localization of dl during the immune response is controlled by the Toll signaling pathway, comprising gene products that participa te in the intracellular part of the embryonic dorsoventral pathway. We also report that in mutants such as Toll or cactus, which exhibit mel anotic tumor phenotypes, dl is constitutively nuclear, Together, these results point to a potential link between the Toll signaling pathway and melanotic tumor induction, Although dl has been shown previously t o bind to kappa B-related motifs within the promoter of the antibacter ial peptide coding gene diptericin, we find that injury-induced expres sion of diptericin can occur in the absence of dl. Furthermore, the me lanotic tumor phenotype of Toll and cactus is not dl dependent. These data underline the complexity of the Drosophila immune response. Final ly, we observed that like other rel proteins, dl can control the level of its own transcription.