Proprotein convertaseFurin1expression in theDrosophilafat body is essential for a normal antimicrobial peptide response and bacterial host defense

Abstract

Invading pathogens provoke robust innate immune responses in Dipteran insects, such as In a systemic bacterial infection, a humoral response is induced in the fat body. Gram-positive bacteria trigger the Toll signaling pathway, whereas gram-negative bacterial infections are signaled the immune deficiency (IMD) pathway. We show here that the RNA interference-mediated silencing of -a member of the proprotein convertase enzyme family-specifically in the fat body, results in a reduction in the expression of antimicrobial peptides. This, in turn, compromises the survival of adult fruit flies in systemic infections that are caused by both gram-positive and -negative bacteria. plays a nonredundant role in the regulation of immune responses, as silencing of , the other member of the enzyme family, had no effect on survival or the expression of antimicrobial peptides upon a systemic infection. does not directly affect the Toll or IMD signaling pathways, but the reduced expression of up-regulates stress response factors in the fat body. We also demonstrate that is a negative regulator of the Janus kinase/signal transducer and activator of transcription signaling pathway, which is implicated in stress responses in the fly. In summary, our data identify as a novel regulator of humoral immunity and cellular stress responses in-Aittomäki, S., Valanne, S., Lehtinen, T., Matikainen, S., Nyman, T. A., Rämet, M., Pesu, M. Proprotein convertase expression in the fat body is essential for a normal antimicrobial peptide response and bacterial host defense.

Proteasome α6 Subunit Negatively Regulates the JAK/STAT Pathway and Blood Cell Activation in Drosophila melanogaster

“…Furins are a family of evolutionarily conserved serine endoprotease enzymes that cleave precursor proteins into their mature forms ( 82 ). In accordance with our results, silencing of Drosophila Fur1 in the fat body has previously been shown to elevate the transcription of stress response genes including the JAK/STAT pathway target gene TotM ( 83 ).…”

Characterisation of early metazoan secretion through associated signal peptidase complex subunits, prohormone convertases and carboxypeptidases of the marine sponge (Amphimedon queenslandica)

“…While 4 to 5 SPs, and 1 to 2 CPs are typically been found in a range of both unicellular and multicellular organisms [11–13], PCs show varied distribution across the tree of life, with yeast Saccharomyces cerevisiae species possessing 1 (Kexin) [4], D . melanogaster having 3 PCs, 2 of which being distinct variants of the same convertase ‘Furin’ [14], while Caenorhabditis elegans possesses 5, 2 of which (blisterase and aex-5) are nematode specific, with blisterase generating 9 isoforms [15]. Similarly, the SPs, PCs and CPs of other metazoa have been determined or predicted.…”

De novo transcriptome analysis and identification of genes associated with immunity, detoxification and energy metabolism from the fat body of the tephritid gall fly, Procecidochares utilis

“…The insect fat body acts as an immune barrier between the internal and external environment, which plays a major role in preventing infection by microbial, protozoan pathogens and other foreign objects [12, 13, 89]. In recent studies, a number of genes associated with immune response were identified from the fat body transcriptome of B .…”