Insulin/IGF signaling regulates the change in commitment in imaginal discs and primordia by overriding the effect of juvenile hormone
Insulin/IGF signaling regulates the change in commitment in imaginal discs and primordia by overriding the effect of juvenile hormone
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DOI：
10.1016/j.ydbio.2008.09.017
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发表时间：
2008-12-15
影响因子：
2.7
通讯作者：
Riddiford, Lynn M.
中科院分区：
文献类型：
--
作者：
Koyama, Takashi;Syropyatova, Maria O.;Riddiford, Lynn M.
在天蛾最后幼虫（第五龄）开始时，包括翼盘和眼原基在内的成虫前体启动变态变化，例如蛹定型、图案形成和细胞增殖。保幼激素（JH）可以防止早期龄期和饥饿的末龄幼虫中的这些变化，但营养摄入克服了 JH 对后者的影响。在这项研究中，我们发现，在饥饿的末龄幼虫中，通过喂食蔗糖或牛胰岛素或曼杜卡家蚕素，翅盘中广泛的蛹定型分子标记被上调。 JH 无法阻止胰岛素的这种作用。体外胰岛素对广泛表达没有影响，但解除了JH对广泛表达的抑制。胰岛素的这种作用直接作用于椎间盘，如胰岛素受体 dsRNA 存在的减少所示。在饥饿的倒数第二个第四龄幼虫中，翼盘中的广泛表达并未被胰岛素上调。在蜕皮到第五龄的过程中，椎间盘对胰岛素的这种作用产生了反应，并且能够响应 20-羟基蜕皮激素而变成蛹。因此，曼杜卡家蚕素在成虫前体中充当变态启动因子。 (C) 2008 Elsevier Inc. 保留所有权利。
At the beginning of the final larval (fifth) instar of Manduca sexta, imaginal precursors including wing discs and eye primordia initiate metamorphic changes, such as pupal commitment, patterning and cell proliferation. juvenile hormone (JH) prevents these changes in earlier instars and in starved final instar larvae, but nutrient intake overcomes this effect of JH in the latter. In this study, we show that a molecular marker of pupal commitment, broad, is up-regulated in the wing discs by feeding on sucrose or by bovine insulin or Manduca bombyxin in starved final instar larvae. This effect of insulin could not be prevented by JH. In vitro insulin had no effect on broad expression but relieved the Suppression of broad expression by JH. This effect of insulin was directly on the disc as shown by its reduction in the presence of insulin receptor dsRNA. In starved penultimate fourth instar larvae, broad expression in the wing disc was not up-regulated by insulin. The discs became responsive to this action of insulin during the molt to the fifth instar together with the ability to become pupally committed in response to 20-hydroxyecdysone. Thus, the Manduca bombyxin acts as a metamorphosis-initiating factor in the imaginal precursors. (C) 2008 Elsevier Inc. All rights reserved.