title: Antimicrobial peptide gene induction, involvement of Toll and IMD pathways and defense against bacteria in the red flour beetle, Tribolium castaneum.
abstract: Using Tribolium castaneum, we quantitatively investigated the induction of nine antimicrobial peptide (AMP) genes by live gram-negative bacteria (Escherichia coli and Enterobacter cloacae), gram-positive bacteria (Micrococcus luteus and Bacillus subtilis) and the budding yeast (Saccharomyces cerevisiae). Then, five representative AMP genes were selected, and the involvement of the Toll and IMD pathways in their induction by E. coli, M. luteus and S. cerevisiae was examined by utilizing RNA interference of either MyD88 or IMD. Results indicated: Robust and acute induction of three genes by the two bacterial species was mediated mainly by the IMD pathway; slow and sustained induction of one gene by the two bacteria was mediated mainly by the Toll pathway; induction of the remaining one gene by the two bacteria was mediated by both pathways; induction of the five genes by the yeast was mediated by the Toll and/or IMD pathways depending on respective genes. These results suggest that more promiscuous activation and usage of the two pathways may occur in T. castaneum than in Drosophila melanogaster. In addition, the IMD pathway was revealed to dominantly contribute to defense against two bacterial species, gram-negative E. cloacae and gram-positive B. subtilis that possesses DAP-type peptidoglycan.
authors.affiliation: Applied Entomology Laboratory, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa, Nagoya 464-8601, Japan.
authors.forename: Kakeru
authors.initials: K
authors.lastname: Yokoi
authors.affiliation: Applied Entomology Laboratory, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa, Nagoya 464-8601, Japan.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Koyama
authors.affiliation: Applied Entomology Laboratory, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa, Nagoya 464-8601, Japan.
authors.forename: Chieka
authors.initials: C
authors.lastname: Minakuchi
authors.affiliation: Applied Entomology Laboratory, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa, Nagoya 464-8601, Japan.
authors.forename: Toshiharu
authors.initials: T
authors.lastname: Tanaka
authors.affiliation: Applied Entomology Laboratory, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa, Nagoya 464-8601, Japan.
authors.forename: Ken
authors.initials: K
authors.lastname: Miura
keywords: AMP, antimicrobial peptide; Antimicrobial peptide; Att1, Attacin1; Att2, Attacin2; Att3, Attacin3; Bs, Bacillus subtilis; Cec2, Cecropin2; Cec3, Cecropin3; Col1, Coleoptericin1; Def1, Defensin1; Def2, Defensin2; Def3, Defensin3; Ec, Escherichia coli; Ecl, Enterobacter cloacae; FADD, Fas-associated death domain containing protein; GNBP, gram-negative binding protein; IMD pathway; Innate immunity; Ml, Micrococcus luteus; PAMP, pathogen-associated molecular pattern; PG, peptidoglycan; PGRP, peptidoglycan recognition protein; PRR, pattern recognition receptor; RNAi, RNA interference; RPL32, ribosomal protein L32; RT-PCR, reverse transcription-PCR; Sc, Saccharomyces cerevisiae; Toll pathway; Tribolium castaneum; dsRNA, double strand RNA; malE, maltose binding protein E; qRT-PCR, real-time quantitative RT-PCR