EXPRESSION AND NUCLEAR TRANSLOCATION OF THE REL NF-KAPPA-B-RELATED MORPHOGEN DORSAL DURING THE IMMUNE-RESPONSE OF DROSOPHILA/

The rel/NF-kappaB-related morphogen dorsal is a maternally expressed g ene which is involved in the control of the dorso-ventral axis during early embryogenesis of Drosophila. We show that this gene is also expr essed in the fat body of larvae and adults of Drosophila as well as in a tumorous blood cell line : its expression is noticeably enhanced up on bacterial (of lipopolysaccharide) challenge. This challenge also in duces within 15-30 min a nuclear translocation of the dorsal protein. The genes encoding inducible antibacterial peptides in Drosophila cont ain kappaB-related nucleotide sequences and we show that the dorsal pr otein can bind to such motifs and sequence-specifically transactivate a reporter gene in co-transfection experiments with a Drosophila cell line. However, in dl1 mutants, in the absence of dorsal protein, the g enes encoding antibacterial peptides retain their inducibility, sugges ting a multifactorial control. The results indicate that in addition t o its role in embryogenesis, dorsal is involved in the immune response of Drosophila. They also strengthen the analogy between the mammalian acute phase response and the insect immune response.