Key Laboratory of Insect Developmental Biology and Evolution, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China.
J Insect Physiol. 2010 Oct;56(10):1436-44. doi: 10.1016/j.jinsphys.2010.02.011. Epub 2010 Mar 9.
Genetic studies in the fruitfly, Drosophila melanogaster, have uncovered a conserved insulin/insulin growth factor signaling (IIS) pathway that regulates nutrition-dependent growth rates of insects. From the silkworm, Bombyx mori, we have identified and characterized several key genes involved in the IIS pathway, including InR, IRS, PI3K110, PI3K60, PTEN, PDK, and Akt. Tissue distribution analysis showed that most of these genes were highly expressed in the fat body implying that the IIS pathway is functionally important within insect adipose tissue. Developmental profile studies revealed that the expression levels of InR, IRS, PI3K110, and PDK were elevated in the fat body during molting and pupation, periods when animals ceased feeding and hemolymph levels of 20-hydroxyecdysone (20E) were high. Starvation rapidly up-regulated the mRNA levels of these same genes in the fat body, while 20E slowly induced their transcription. We conclude that 20E slowly reduces food consumption and then indirectly induces a state of starvation resulting in the elevation of the mRNA levels of InR, IRS, PI3K110, and PDK in the Bombyx fat body during molting and pupation.
在果蝇中进行的遗传研究揭示了一条保守的胰岛素/胰岛素样生长因子信号通路（IIS），它调节昆虫的营养依赖性生长速度。我们从家蚕（Bombyx mori）中鉴定并表征了几个参与 IIS 通路的关键基因，包括 InR、IRS、PI3K110、PI3K60、PTEN、PDK 和 Akt。组织分布分析表明，这些基因中的大多数在脂肪体中高度表达，这表明 IIS 通路在昆虫脂肪组织中具有重要的功能。发育谱研究表明，InR、IRS、PI3K110 和 PDK 的表达水平在蜕皮和蛹化期间的脂肪体中升高，此时动物停止进食，血液中的 20-羟基蜕皮酮（20E）水平较高。饥饿会迅速上调脂肪体中这些基因的 mRNA 水平，而 20E 则缓慢诱导其转录。我们得出结论，20E 会缓慢减少食物摄取量，然后间接导致饥饿状态，从而导致在蜕皮和蛹化期间，Bombyx 脂肪体中 InR、IRS、PI3K110 和 PDK 的 mRNA 水平升高。
