title: Drosophila 14-3-3ε has a crucial role in anti-microbial peptide secretion and innate immunity.
abstract: The secretion of anti-microbial peptides is recognised as an essential step in innate immunity, but there is limited knowledge of the molecular mechanism controlling the release of these effectors from immune response cells. Here, we report that Drosophila 14-3-3ε mutants exhibit reduced survival when infected with either Gram-positive or Gram-negative bacteria, indicating a functional role for 14-3-3ε in innate immunity. In 14-3-3ε mutants, there was a reduced release of the anti-microbial peptide Drosomycin into the haemolymph, which correlated with an accumulation of Drosomycin-containing vesicles near the plasma membrane of cells isolated from immune response tissues. Drosomycin appeared to be delivered towards the plasma membrane in Rab4- and Rab11-positive vesicles and smaller Rab11-positive vesicles. RNAi silencing of Rab11 and Rab4 significantly blocked the anterograde delivery of Drosomycin from the perinuclear region to the plasma membrane. However, in 14-3-3ε mutants there was an accumulation of small Rab11-positive vesicles near the plasma membrane. This vesicular phenotype was similar to that observed in response to the depletion of the vesicular Syntaxin protein Syx1a. In wild-type Drosophila immune tissue, 14-3-3ε was detected adjacent to Rab11, and partially overlapping with Syx1a, on vesicles near the plasma membrane. We conclude that 14-3-3ε is required for Rab11-positive vesicle function, which in turn enables antimicrobial peptide secretion during an innate immune response.
authors.affiliation: Division of Human Immunology, Centre for Cancer Biology, Adelaide SA5000, Australia. Tetyana.Shandala@unisa.edu.au
authors.forename: Tetyana
authors.initials: T
authors.lastname: Shandala
authors.forename: Joanna M
authors.initials: JM
authors.lastname: Woodcock
authors.forename: Yeap
authors.initials: Y
authors.lastname: Ng
authors.forename: Lisa
authors.initials: L
authors.lastname: Biggs
authors.forename: Efthimios M C
authors.initials: EM
authors.lastname: Skoulakis
authors.forename: Doug A
authors.initials: DA
authors.lastname: Brooks
authors.forename: Angel F
authors.initials: AF
authors.lastname: Lopez
mesh_terms: D048948:14-3-3 Proteins / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D000890:Anti-Infective Agents / Q000494:pharmacology; D023181:Antimicrobial Cationic Peptides / Q000096:biosynthesis* / Q000378:metabolism; D001692:Biological Transport / Q000235:genetics; D002462:Cell Membrane / Q000235:genetics / Q000378:metabolism; D029721:Drosophila Proteins / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000187:drug effects / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D015870:Gene Expression; D007113:Immunity, Innate; D009154:Mutation; D050765:Qa-SNARE Proteins / Q000172:deficiency / Q000378:metabolism; D034622:RNA Interference; D034741:RNA, Small Interfering; D020691:rab GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D020695:rab4 GTP-Binding Proteins / Q000235:genetics; D000099193:rab11 GTP-Binding Proteins
chemical_list: D048948:14-3-3 Proteins; D000890:Anti-Infective Agents; D023181:Antimicrobial Cationic Peptides; D029721:Drosophila Proteins; D050765:Qa-SNARE Proteins; D034741:RNA, Small Interfering; D020691:rab GTP-Binding Proteins; D020695:rab4 GTP-Binding Proteins; C091227:DRS protein, Drosophila; C559123:Rab11 protein, Drosophila; D000099193:rab11 GTP-Binding Proteins