Onecut is a direct neural-specific transcriptional activator of Rx in Ciona intestinalis
Onecut is a direct neural-specific transcriptional activator of Rx in Ciona intestinalis
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DOI：
10.1016/j.ydbio.2011.05.584
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发表时间：
2011-07-15
影响因子：
2.7
通讯作者：
Branno, Margherita
中科院分区：
文献类型：
--
作者：
D'Aniello, Enrico;Pezzotti, Maria Rosa;Branno, Margherita
视网膜同源盒基因在后生动物前神经板的发育中起着重要而保守的作用。在脊索动物的进化过程中，它们还获得了控制眼睛形成和神经发生的新功能。为了表征Rx遗传级联并阐明导致获得这种眼睛发育新作用的机制，我们使用海鞘，玻璃海鞘研究了Rx转录调控。通过对Ci-Rx启动子的缺失分析，我们鉴定了两种不同的增强子元件，能够诱导Ci-Rx在中枢神经系统前部以及尾芽和幼虫阶段的感光器官中特异性表达。生物信息学分析强调了这些增强子中包含的两个Onecut结合位点的存在，因此我们探索了这种转录因子在Ci-Rx调节中的作用。通过原位杂交，我们首次证实了这些基因在相同的细胞中共表达。通过一系列体内和体外实验，我们证明了两个Onecut位点负责Ci-Rx内源性区域中的增强子激活。我们还证明了在体内Onecut错误表达能够诱导Rx启动子的异位激活。最后，我们证明了Ci-Onecut能够促进感觉囊泡中的Ci-Rx表达。总之，这些结果支持以下结论：在玻璃海鞘胚胎发生中，Ci-Rx表达受Onecut转录因子的控制，并且该因子对于通过两个增强子元件特异性激活Ci-Rx是必要且足够的。(C)2011 Elsevier Inc. All rights reserved.
Retinal homeobox (Rx) genes play a crucial and conserved role in the development of the anterior neural plate of metazoans. During chordate evolution, they have also acquired a novel function in the control of eye formation and neurogenesis. To characterize the Rx genetic cascade and shed light on the mechanisms that led to the acquisition of this new role in eye development, we studied Rx transcriptional regulation using the ascidian, Ciona intestinalis. Through deletion analysis of the Ci-Rx promoter, we have identified two distinct enhancer elements able to induce Ci-Rx specific expression in the anterior part of the CNS and in the photosensory organ at tailbud and larva stages. Bioinformatic analysis highlighted the presence of two Onecut binding sites contained in these enhancers, so we explored the role of this transcription factor in the regulation of Ci-Rx. By in situ hybridization, we first confirmed that these genes are co-expressed in the same cells. Through a series of in vivo and in vitro experiments, we then demonstrated that the two Onecut sites are responsible for enhancer activation in Ci-Rx endogenous territories. We also demonstrated in vivo that Onecut misexpression is able to induce ectopic activation of the Rx promoter. Finally, we demonstrated that Ci-Onecut is able to promote Ci-Rx expression in the sensory vesicle. Together, these results support the conclusion that in Ciona embryogenesis, Ci-Rx expression is under the control of the Onecut transcription factor and that this factor is necessary and sufficient to specifically activate Ci-Rx through two enhancer elements. (C) 2011 Elsevier Inc. All rights reserved.