Resumen de The role of the spn42dd serpin in the innate immune response in drosophila melanogaster
The Drosophila genome encodes 29 serpin genes, the biological functions of most which are unknown. In this report, the biochemical and functional characterisation of Serpin42Dd (Spn42Dd, synonyms: Spn1, CG9456) is presented. Spn42Dd inhibits trypsin in vitro and regulates the Toll-mediated immune response in vivo. Both the transcription and protein levels of Spn42Dd are up-regulated in flies infected by Grampositive bacteria and fungi. Moreover, transgenic flies over-expressing spn42Dd show reduced expression of drosomycin antimicrobial peptide after fungal, but not bacterial challenge.
The Toll-mediated anti-fungal immune response can be activated either by the pattern recognition receptor, GNBP3, or the virulence-factor (danger-signalling) response. The danger-signalling pathway senses both fungal and Gram-positive bacterial virulence factors and involves the serine protease Persephone. Spn42Dd does not affect this Persephone-dependent branch of the Toll-signalling pathway, which is independently modulated by the Necrotic serpin (Spn43Ac, CG1857). In fact, epistatic analysis places the Spn42Dd inhibitor downstream of the GNBP3 receptor and upstream of the Grass protease.
