title: Relish2 mediates bursicon homodimer-induced prophylactic immunity in the mosquito Aedes aegypti.
abstract: Bursicon is a neuropeptide hormone consisting of two cystine-knot proteins (burs α and burs β), responsible for cuticle tanning and other developmental processes in insects. Recent studies show that each bursicon subunit forms homodimers that induce prophylactic immunity in Drosophila melanogaster. Here, we investigated the hypothesis that bursicon homodimers act in prophylactic immunity in insects, and possibly arthropods, generally, using the mosquito, Aedes aegypti. We found that burs α and burs β are expressed in larvae, pupae and newly emerged adults. Treating newly emerged Ae. aegypti and D. melanogaster adults with recombinant bursicon (r-bursicon) heterodimer led to cuticle tanning in both species. Treating larvae and adults with r-bursicon homodimers led to up-regulation of five anti-microbial peptide (AMP) genes, noting the possibility that bursicon heterodimers also lead to up-regulation of these genes can not been excluded. The induced AMPs effectively suppressed the growth of bacteria in vitro. RNAi knock-down of the transcriptional factor Relish2 abolished the influence of r-bursicon homodimers on AMP production. We infer the bursicon homodimers induce expression of AMP genes via Relish2 in Ae. aegypti, as prophylactic immunity to protect mosquitoes during the vulnerable stages of each molt.
authors.affiliation: Division of Plant Sciences, University of Missouri, Columbia, Missouri, USA.
authors.forename: Hongwei
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Division of Plant Sciences, University of Missouri, Columbia, Missouri, USA.
authors.forename: Shengzhang
authors.initials: S
authors.lastname: Dong
authors.affiliation: Division of Plant Sciences, University of Missouri, Columbia, Missouri, USA.
authors.forename: Xi
authors.initials: X
authors.lastname: Chen
authors.affiliation: USDA/Agricultural Research Service, Biological Control of Insects Research Laboratory, Columbia, Missouri, USA.
authors.forename: David
authors.initials: D
authors.lastname: Stanley
authors.affiliation: Department of Veterinary Pathobiology, University of Missouri, Columbia, Missouri, USA.
authors.forename: Brenda
authors.initials: B
authors.lastname: Beerntsen
authors.affiliation: Guangzhou Key Laboratory of Insect Development Regulation and Application Research, School of Life Sciences, South China Normal University, Guangzhou, China.
authors.forename: Qili
authors.initials: Q
authors.lastname: Feng
authors.affiliation: Division of Plant Sciences, University of Missouri, Columbia, Missouri, USA.
authors.forename: Qisheng
authors.initials: Q
authors.lastname: Song
mesh_terms: D000330:Aedes / Q000276:immunology*; D000818:Animals; D023181:Antimicrobial Cationic Peptides / Q000096:biosynthesis; D001419:Bacteria / Q000187:drug effects / Q000254:growth & development; D020869:Gene Expression Profiling; D019476:Insect Proteins / Q000378:metabolism*; D007447:Invertebrate Hormones / Q000378:metabolism*; D007814:Larva / Q000276:immunology; D011679:Pupa / Q000276:immunology; D013633:Tanning
chemical_list: D023181:Antimicrobial Cationic Peptides; D019476:Insect Proteins; D007447:Invertebrate Hormones; C002295:bursicon