Key Laboratory of Developmental and Evolutionary Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China.
BMC Genomics. 2010 Oct 9;11:549. doi: 10.1186/1471-2164-11-549.
Insect innate immunity can be affected by juvenile hormone (JH) and 20-hydroxyecdysone (20E), but how innate immunity is developmentally regulated by these two hormones in insects has not yet been elucidated. In the silkworm, Bombyx mori, JH and 20E levels are high during the final larval molt (4 M) but absent during the feeding stage of 5(th) instar (5 F), while JH level is low and 20E level is high during the prepupal stage (PP). Fat body produces humoral response molecules and hence is considered as the major organ involved in innate immunity.
A genome-wide microarray analysis of Bombyx fat body isolated from 4 M, 5 F and PP uncovered a large number of differentially-expressed genes. Most notably, 6 antimicrobial peptide (AMP) genes were up-regulated at 4 M versus PP suggesting that Bombyx innate immunity is developmentally regulated by the two hormones. First, JH treatment dramatically increased AMP mRNA levels and activities. Furthermore, 20E treatment exhibited inhibitory effects on AMP mRNA levels and activities, and RNA interference of the 20E receptor EcR-USP had the opposite effects to 20E treatment.
Taken together, we demonstrate that JH acts as an immune-activator while 20E inhibits innate immunity in the fat body during Bombyx postembryonic development.
昆虫先天免疫可以受到保幼激素（JH）和 20-羟基蜕皮酮（20E）的影响，但这两种激素如何在昆虫中调节先天免疫的发育仍不清楚。在桑蚕（Bombyx mori）中，JH 和 20E 的水平在最后一次幼虫蜕皮（4M）期间较高，但在 5 龄幼虫的取食阶段（5F）期间不存在，而在预蛹阶段（PP）时 JH 水平较低，20E 水平较高。脂肪体产生体液反应分子，因此被认为是参与先天免疫的主要器官。
对来自 4M、5F 和 PP 的桑蚕脂肪体进行的全基因组微阵列分析揭示了大量差异表达的基因。最值得注意的是，6 种抗菌肽（AMP）基因在 4M 时相对于 PP 上调，表明 Bombyx 先天免疫受到这两种激素的发育调节。首先，JH 处理显著增加了 AMP mRNA 水平和活性。此外，20E 处理对 AMP mRNA 水平和活性表现出抑制作用，而 20E 受体 EcR-USP 的 RNA 干扰则具有与 20E 处理相反的效果。
综上所述，我们证明了 JH 作为免疫激活剂，而 20E 在 Bombyx 胚胎后发育期间抑制脂肪体的先天免疫。
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