title: The serine protease Sp7 is expressed in blood cells and regulates the melanization reaction in Drosophila.
abstract: Serine proteases play a central role in defense against pathogens by regulating processes such as blood clotting, melanization of injured surfaces, and proteolytic activation of signaling pathways involved in innate immunity. Here, we present the functional characterization of the Drosophila serine protease Sp7 (CG3006) by inducible RNA interference. We show that Sp7 is constitutively expressed in blood cells during embryonic and larval stages. Silencing of the gene impairs the melanization reaction upon injury. Our data demonstrate that Sp7 is required for phenoloxidase activation and its activity is restricted to a subclass of blood cells, the crystal cells. Transcriptional up-regulation of Sp7 was observed after clean, septic injury and in flies expressing an activated form of Toll; however, mutations in the Toll or the IMD pathway did not abolish expression of Sp7, indicating the existence of other regulatory pathways and/or independent basal transcription.
authors.affiliation: Department of Experimental Medical Science and Lund Strategic Research Center for Stem Cell Biology and Cell Therapy, Lund University, BMC B13, Klinikgatan 26, 22184 Lund, Sweden. Casimiro.Castillejo-Lopez@med.lu.se
authors.forename: Casimiro
authors.initials: C
authors.lastname: Castillejo-López
authors.forename: Udo
authors.initials: U
authors.lastname: Häcker
mesh_terms: D000818:Animals; D001773:Blood Cells / Q000201:enzymology* / Q000276:immunology*; D002268:Carboxypeptidases / Q000097:blood* / Q000276:immunology*; D004330:Drosophila / Q000201:enzymology* / Q000276:immunology*; D029721:Drosophila Proteins / Q000097:blood* / Q000276:immunology*; D005786:Gene Expression Regulation / Q000276:immunology; D006458:Hemolymph / Q000276:immunology / Q000378:metabolism; D007113:Immunity, Innate / Q000276:immunology; D007155:Immunologic Factors / Q000276:immunology; D008543:Melanins / Q000276:immunology*; D018805:Sepsis / Q000201:enzymology* / Q000276:immunology*; D012697:Serine Endopeptidases
chemical_list: D029721:Drosophila Proteins; D007155:Immunologic Factors; D008543:Melanins; D002268:Carboxypeptidases; D012697:Serine Endopeptidases; C506883:Sp7 protein, Drosophila