TGF-β signaling in insects regulates metamorphosis via juvenile hormone biosynthesis
TGF-β signaling in insects regulates metamorphosis via juvenile hormone biosynthesis
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DOI：
10.1073/pnas.1600612113
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发表时间：
2016-05-17
影响因子：
11.1
通讯作者：
Mito, Taro
中科院分区：
文献类型：
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作者：
Ishimaru, Yoshiyasu;Tomonari, Sayuri;Mito, Taro
虽然蝴蝶经历了从幼虫到成虫的戏剧性的形态转变(全变态)，但蟋蟀经历了从若虫到成虫的变态，而没有形成蛹(半变态)。尽管有这些差异，但这两个过程都受到共同的机制的调节，涉及20-羟基蜕皮激素(20E)和保幼激素(JH)。JH调节昆虫生理的许多方面，如发育、繁殖、滞育和变态。因此，在昆虫的整个生命周期中，严格调节JH水平是至关重要的。然而，目前还不清楚JH合成是如何调控的。在这里，我们报道了在蟋蟀的舌体中，果蝇Myoglianin/脊椎动物GDF8/11的同源物Myoglianin(GB‘Myo)通过抑制JH酸O-甲基转移酶基因GB’jhamt的表达而下调JH的合成。相反，JH的产生被Decapentaplegic(GB‘Dpp)和Glass-Bottom Boat/60A(GB’Gbb)信号上调，这是GB‘jhamt转录激活的一部分。GB‘Myo通过调节JH滴度和JH与20E之间的相互作用来定义每个发育转变的性质。当Gb‘myo表达被抑制时，Gb’jhamt表达的激活和20E的分泌诱导蜕皮，从而导致下一龄早于最后一龄若虫。相反，Gb‘myo的高表达通过停止JH的合成来诱导最后一龄若虫的变态。GB‘myo还控制最终昆虫的大小。由于Myo/GDF8/11和DPP/骨形态发生蛋白(BMP)2/4-GBB/BMP5-8在无脊椎动物和脊椎动物中都是保守的，因此本研究结果为动物发育的内分泌调控提供了共同的调控机制。
Although butterflies undergo a dramatic morphological transformation from larva to adult via a pupal stage (holometamorphosis), crickets undergo a metamorphosis from nymph to adult without formation of a pupa (hemimetamorphosis). Despite these differences, both processes are regulated by common mechanisms that involve 20-hydroxyecdysone (20E) and juvenile hormone (JH). JH regulates many aspects of insect physiology, such as development, reproduction, diapause, and metamorphosis. Consequently, strict regulation of JH levels is crucial throughout an insect's life cycle. However, it remains unclear how JH synthesis is regulated. Here, we report that in the corpora allata of the cricket, Gryllus bimaculatus, Myoglianin (Gb'Myo), a homolog of Drosophila Myoglianin/vertebrate GDF8/11, is involved in the down-regulation of JH production by suppressing the expression of a gene encoding JH acid O-methyltransferase, Gb'jhamt. In contrast, JH production is up-regulated by Decapentaplegic (Gb'Dpp) and Glass-bottom boat/60A (Gb'Gbb) signaling that occurs as part of the transcriptional activation of Gb'jhamt. Gb'Myo defines the nature of each developmental transition by regulating JH titer and the interactions between JH and 20E. When Gb'myo expression is suppressed, the activation of Gb'jhamt expression and secretion of 20E induce molting, thereby leading to the next instar before the last nymphal instar. Conversely, high Gb'myo expression induces metamorphosis during the last nymphal instar through the cessation of JH synthesis. Gb'myo also regulates final insect size. Because Myo/GDF8/11 and Dpp/bone morphogenetic protein (BMP) 2/4-Gbb/BMP5-8 are conserved in both invertebrates and vertebrates, the present findings provide common regulatory mechanisms for endocrine control of animal development.