Reconstructed evolution of insulin receptors in insects reveals duplications in early insects and cockroaches
Reconstructed evolution of insulin receptors in insects reveals duplications in early insects and cockroaches
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DOI：
10.1002/jez.b.22809
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发表时间：
2018-07-01
影响因子：
2.2
通讯作者：
Bornberg-Bauer, Erich
中科院分区：
文献类型：
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作者：
Kremer, Lukas Peter Maria;Korb, Judith;Bornberg-Bauer, Erich
群居昆虫表现出极高的表型可塑性。在高度社会化的物种中，这表现在不同种姓的产生，在形态和寿命上都有极大的差异。这些差异的分子基础是高度纠缠和不完全理解，但最近的几项研究表明，胰岛素/胰岛素样生长因子信号转导（IIS）是关键途径之一。在这里，我们调查昆虫胰岛素受体（InRs），这是膜结合的二聚体，使IIS通过中继细胞外信号到细胞内信号级联的分子进化。无脊椎动物IIS的经典模型只包括一个InR基因，但最近对不太常研究的昆虫的一些研究发现了两个InR，它们以拮抗的方式起作用，以促进至少一个记录病例中的多表型。我们搜索了22个节肢动物基因组，并确定了几个INR副本和它们的进化起源，缺乏从以前的注释。系统发育分析表明，这两种昆虫的InR基因至少可以追溯到4亿年前，它们是有翅昆虫的共同祖先。最值得注意的是，我们还确定了第三个InR副本的进化起源，这是独特的Blattodea的分支，就在那里的真社会性白蚁进化。其中一个InR旁系同源物在所有三种白蚁中都表现出种姓偏见的表达，这强烈表明了种姓分化的作用。这些结果对过去和未来昆虫中的InR抑制/InR敲低实验具有重要的影响，并且它们提供了一组调节白蚁种姓寿命和形态的关键基因。
Social insects show an extreme degree of phenotypic plasticity. In highly eusocial species, this manifests in the generation of distinct castes with extreme differences in both morphology and life span. The molecular basis of these differences is highly entangled and not fully understood, but several recent studies demonstrated that insulin/insulin-like growth factor signaling (IIS) is one of the key pathways. Here, we investigate the molecular evolution of insect insulin receptors (InRs), which are membrane-bound dimers that enable IIS by relaying extracellular signals to intracellular signaling cascades. Classic models of invertebrate IIS include only one InR gene, but some recent studies on less commonly studied insects have found two InRs, which act in an antagonistic manner to facilitate polyphenism in at least one documented case. We search 22 arthropod genomes and identify several InR copies and their evolutionary origin that were lacking from previous annotations. Phylogenetic analysis shows that the two insect InR genes date back at least 400 million years to a common ancestor of winged insects. Most notably, we also identified the evolutionary origin of a third InR copy that is unique to the clade of Blattodea, just before therein the eusocial termites evolved. One of the InR paralogs consistently shows caste-biased expression in all three termites, which strongly suggests a role in caste differentiation. These results have important ramifications for past and future InR inhibition/InR knockdown experiments in insects and they provide a set of key genes regulating life span and morphology in termite castes.