Juvenile hormone: The status of its ''status quo'' action
Juvenile hormone: The status of its ''status quo'' action
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DOI：
10.1002/(sici)1520-6327(1996)32:3/4
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发表时间：
1996-01-01
影响因子：
2.2
通讯作者：
Riddiford, LM
中科院分区：
文献类型：
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作者：
Riddiford, LM
保幼激素（JH）允许幼虫蜕皮，蜕皮激素的反应，但阻止变态所必需的基因表达的开关。我首先回顾了我们的努力，分离JH的幼虫表皮的天蛾使用光亲和类似物和我们最近的研究结果，分离的分子不结合JH我与高亲和力的核受体。所报道的重组29 kDa蛋白（rJP 29）与JH I的表观高亲和力结合是人为的，因为存在污染性酯酶。纯化的rJP 29结合几乎检测不到的JH I，但其结合的光亲和类似物被阻止JH I以及其他类异戊二烯，表明这些化合物的低亲和力。我们最近的研究重点是JH对20-羟基蜕皮酮（20 E）诱导的早期分子事件的影响。用10（-6）M 20 E培养24 h，第2 ~ 5天幼虫的表皮首先发生蛹的定型，然后发生化蛹所必需的预分化事件。蜕皮激素受体的两种亚型（EcR-A和EcR-B1）和E75 A（一种蜕皮激素诱导的转录因子）的mRNA的双相增加与这两个阶段相吻合。超气门（USP）和变态特异性宽复合物（BR-C）的mRNA仅在第二阶段增加。JH的存在对EcR mRNA的初始增加没有影响，但引起E75 A mRNA的积累增加。这种JH也阻止了EcR，USP和BR-C mRNA的后期变化。因此，JH只影响了20 E的某些早期行动，这些行动随后导致了它对“现状”的保留。“（C）1996 Wiley-Liss，Inc.
Juvenile hormone (JH) allows larval molting in response to ecdysteroids but prevents the switching of gene expression necessary for metamorphosis. I first review our efforts to isolate the nuclear receptor for JH in the larval epidermis of Manduca sexta using photoaffinity analogs and our recent findings that the molecule isolated does not bind JH I with high affinity. The reported apparent high affinity binding of JH I by the recombinant 29 kDa protein (rJP29) was artifactual due to the presence of contaminating esterases. Purified rJP29 bound little detectable JH I, but its binding of the photoaffinity analog was prevented by JH I as well as other isoprenoids, indicating a low affinity for these compounds. Our recent studies focus on the effects of JH on the early molecular events induced by 20-hydroxyecdysone (20E). Culture of day 2 5th larval epidermis with 10(-6)M 20E for 24 h caused first pupal commitment, then the onset of the predifferentiative events necessary for pupation. Biphasic increases in the mRNAs of the two isoforms of the ecdysone receptor (EcR-A and EcR-B1) and of E75A, an ecdysteroid-induced transcription factor, coincided with these two phases. The mRNAs for Ultraspiracle (USP) and the metamorphosis-specific Broad-Complex (BR-C) increased only during the second phase. The presence of JH had no effect on the initial increases in EcR mRNAs but caused an increased accumulation of E75A mRNA. This JH also prevented the later changes in EcR, USP, and BR-C mRNAs. Thus, JH influences only certain of the early actions of 20E which then result in its preservation of the ''status quo.'' (C) 1996 Wiley-Liss, Inc.