The silkworm glutathione S-transferase gene noppera-bo is required for ecdysteroid biosynthesis and larval development
The silkworm glutathione S-transferase gene noppera-bo is required for ecdysteroid biosynthesis and larval development
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DOI：
10.1016/j.ibmb.2015.04.001
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发表时间：
2015-06-01
影响因子：
3.8
通讯作者：
Niwa, Ryusuke
中科院分区：
文献类型：
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作者：
Enya, Sora;Daimon, Takaaki;Niwa, Ryusuke
昆虫的蜕皮和变态受到蜕皮甾体激素的严格控制，蜕皮甾体激素是由前胸腺中的膳食固醇合成的重要类固醇激素。在果蝇黑腹果蝇（Drosophila melanogaster）中，有一种产生蜕皮甾体的基因是noppera-bo (nobo)，也被称为GSTe14，它编码谷胱甘肽s -转移酶的epsilon类成员。在黑腹大鼠中，nobo通过调节胆固醇在前胸腺的转运和/或代谢，在利用胆固醇方面起着至关重要的作用。然而，目前尚不清楚来自其他昆虫的nobo的直系同源物是否也通过胆固醇运输和/或前胸腺代谢参与外甾体生物合成。在这里，我们报告的遗传证据表明，家蚕的同源物nobo （nobo- bm; GSTe7）对家蚕的发育至关重要。nobo-Bm主要表达于前胸腺。为了评估nobo-Bm的功能重要性，我们使用talen介导的基因组编辑生成了一个nobo-Bm的家蚕基因突变体。我们发现nobo-Bm功能的丧失导致幼虫停滞和光滑的角质层表型，这是通过应用20-羟基蜕皮激素来拯救的。此外，从nobo-Bm突变体中分离的前胸腺细胞表现出7-脱氢胆固醇（一种胆固醇代谢物）的异常积累。这些结果表明nobo家族谷胱甘肽s -转移酶在双翅目和鳞翅目昆虫的发育和前胸腺固醇利用的调控中都是必不可少的。另一方面，nobo功能突变体缺失后，黑腹家蚕和家蚕体内的甾醇积累异常，说明这两种昆虫对甾醇的利用存在一定差异。(C) 2015 Elsevier Ltd.版权所有。
Insect molting and metamorphosis are tightly controlled by ecdysteroids, which are important steroid hormones that are synthesized from dietary sterols in the prothoracic gland. One of the ecdysteroido-genic genes in the fruit fly Drosophila melanogaster is noppera-bo (nobo), also known as GSTe14, which encodes a member of the epsilon class of glutathione S-transferases. In D. melanogaster, nobo plays a crucial role in utilizing cholesterol via regulating its transport and/or metabolism in the prothoracic gland. However, it is still not known whether the orthologs of nobo from other insects are also involved in ecdysteroid biosynthesis via cholesterol transport and/or metabolism in the prothoracic gland. Here we report genetic evidence showing that the silkworm Bombyx mori ortholog of nobo (nobo-Bm; GSTe7) is essential for silkworm development. nobo-Bm is predominantly expressed in the prothoracic gland. To assess the functional importance of nobo-Bm, we generated a B. mori genetic mutant of nobo-Bm using TALEN-mediated genome editing. We show that loss of nobo-Bm function causes larval arrest and a glossy cuticle phenotype, which are rescued by the application of 20-hydroxyecdysone. Moreover, the prothoracic gland cells isolated from the nobo-Bm mutant exhibit an abnormal accumulation of 7-dehydrocholesterol, a cholesterol metabolite. These results suggest that the nobo family of glutathione S-transferases is essential for development and for the regulation of sterol utilization in the prothoracic gland in not only the Diptera but also the Lepidoptera. On the other hand, loss of nobo function mutants of D. melanogaster and B. mori abnormally accumulates different sterols, implying that the sterol utilization in the PG is somewhat different between these two insect species. (C) 2015 Elsevier Ltd. All rights reserved.