Tissue-specific inducible expression of antimicrobial peptide genes in Drosophila surface epithelia

The production of antimicrobial peptides is an important aspect of host def ense in multicellular organisms. In Drosophila, seven antimicrobial peptide s with different spectra of activities are synthesized by the fat body duri ng the immune response and secreted into the hemolymph. Using GFP reporter transgenes, we show here that all seven Drosophila antimicrobial peptides c an be induced in surface epithelia in a tissue-specific manner. The imd gen e plays a critical role in the activation of this local response to infecti on. In particular, drosomycin expression, which is regulated by the Toll pa thway during the systemic response, is regulated by imd in the respiratory tract, thus demonstrating the existence of distinct regulatory mechanisms f or local and systemic induction of antimicrobial peptide genes in Drosophil a.