Caught in the evolutionary act:: Precise cis-regulatory basis of difference in the organization of gene networks of sea stars and sea urchins
Caught in the evolutionary act:: Precise cis-regulatory basis of difference in the organization of gene networks of sea stars and sea urchins
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DOI：
10.1016/j.ydbio.2007.09.006
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发表时间：
2007-12-15
影响因子：
2.7
通讯作者：
Davidson, Eric H.
中科院分区：
文献类型：
--
作者：
Hinman, Veronica F.;Nguyen, Albert;Davidson, Eric H.
海胆Strongylocentrotus purpuratus和海星星Asterina miniata中otx β 1/2的调控提供了一个特殊的机会，以确定基因调控网络（GRN）架构中进化变化的基因组基础。在这两个类群的网络扰动分析表明，Otx调节的转录因子gastrin和krox/blimpl和这两个转录因子也反馈和调节otx。otx基因也会自动调节。这种三向交互是GRN内核的一个示例。自从这两个类群最后分享一个共同的祖先以来，它已经被保存了5亿年。在这种高水平的保护中，我们在这里展示了一个重要的监管变化。TBrain是在海星星中正确表达otx β 1/2所必需的，但在海胆中不是。在海胆中，tbrain不与otx beta 1/2共表达，而是在胚胎骨骼的特化中起重要作用。因此，这些棘皮动物中的Tbrain是一个完美的例子，说明一个正向基因被选择用于完全不同的发育过程。我们分离并测试了海星星otx β 1/2顺式调节模块，并证明了每个预测输入的功能结合位点，包括Tbrain。我们将其与海胆otx β 1/2顺式调节模块中的逻辑处理进行比较，并提出了一个Tbrain依赖性变化的进化方案。最后，种间基因转移实验证实了这种情况下，并证明进化发生在顺式调控模块的序列变化的水平。(c)2007爱思唯尔公司All rights reserved.
The regulatory control of otx beta 1/2 in the sea urchin Strongylocentrotus purpuratus and the sea star Asterina miniata provides an exceptional opportunity to determine the genomic basis of evolutionary change in gene regulatory network (GRN) architectures. Network perturbation analyses in both taxa show that Otx regulates the transcription factors gatae and krox/blimpl and both of these transcription factors also feed back and regulate otx. The otx gene also autoregulates. This three way interaction is an example of a GRN kernel. It has been conserved for 500 million years since these two taxa last shared a common ancestor. Amid this high level of conservation we show here one significant regulatory change. Tbrain is required for correct otx beta 1/2 expression in the sea star but not in the sea urchin. In sea urchin, tbrain is not co-expressed with otx beta 1/2 and instead has an essential role in specification of the embryonic skeleton. Tbrain in these echinoderms is thus a perfect example of an orthologous gene co-opted for entirely different developmental processes. We isolate and test the sea star otx beta 1/2 cis-regulatory module and demonstrate functional binding sites for each of the predicted inputs, including Tbrain. We compare it to the logic processing operating in the sea urchin otx beta 1/2 cis-regulatory module and present an evolutionary scenario of the change in Tbrain dependence. Finally, inter-specific gene transfer experiments confirm this scenario and demonstrate evolution occurring at the level of sequence changes to the cis-regulatory module. (c) 2007 Elsevier Inc. All rights reserved.