Yokoi Kakeru, Koyama Hiroaki, Minakuchi Chieka, Tanaka Toshiharu, Miura Ken
Applied Entomology Laboratory, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa, Nagoya 464-8601, Japan.
Results Immunol. 2012 Mar 30;2:72-82. doi: 10.1016/j.rinim.2012.03.002. eCollection 2012.
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.
我们利用赤拟谷盗，定量研究了活的革兰氏阴性菌（大肠杆菌和阴沟肠杆菌）、革兰氏阳性菌（藤黄微球菌和枯草芽孢杆菌）以及出芽酵母（酿酒酵母）对9种抗菌肽（AMP）基因的诱导作用。然后，挑选了5个具有代表性的AMP基因，通过对髓样分化因子88（MyD88）或IMD进行RNA干扰，研究了Toll和IMD信号通路在大肠杆菌、藤黄微球菌和酿酒酵母诱导这些基因表达过程中的作用。结果表明：两种细菌对三个基因的强烈且快速诱导主要由IMD信号通路介导；两种细菌对一个基因的缓慢且持续诱导主要由Toll信号通路介导；两种细菌对另一个基因的诱导由两条信号通路共同介导；酵母对这五个基因的诱导作用则因基因不同，由Toll和/或IMD信号通路介导。这些结果表明，相较于黑腹果蝇，赤拟谷盗中这两条信号通路的激活和使用可能更为混杂。此外，研究还发现IMD信号通路在抵御革兰氏阴性菌阴沟肠杆菌和含有二氨基庚二酸（DAP）型肽聚糖的革兰氏阳性菌枯草芽孢杆菌的过程中起主要作用。
