Direct activation by Ets and Zic is required for initial expression of the Brachyury gene in the ascidian notochord
Direct activation by Ets and Zic is required for initial expression of the Brachyury gene in the ascidian notochord
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DOI：
10.1016/j.ydbio.2007.03.034
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发表时间：
2007-06-15
影响因子：
2.7
通讯作者：
Nishida, Hiroki
中科院分区：
文献类型：
--
作者：
Matsumoto, Jun;Kumano, Gaku;Nishida, Hiroki
外源性成纤维细胞生长因子（FGF）信号以及决定信号接收卵裂球对FGF反应的内源性因子调控着柄海鞘（Halocynthia roretzi）胚胎中的中胚层模式形成。为了研究细胞如何整合来自外源性和内源性输入的信息，我们检测了早期胚胎中短尾素（H r - B r a）启动子的活性。H r - B r a编码一种脊索发育的关键转录因子，它以依赖于FGF - MEK - MAPK - Ets信号通路以及内源性因子Zic和FoxA的方式，特异性地在脊索前体细胞中表达。通过用LacZ探针进行原位杂交，早在110细胞期就在脊索前体细胞中检测到由H r - B r a启动子900bp上游区域驱动的报告基因表达。缺失分析结合MEK抑制剂处理表明， - 598 / - 499区域具有FGF反应性。电泳迁移率变动分析在该区域鉴定出三个Ets结合位点，它们对启动子活性是必需的。通过以更高浓度向卵子注射报告基因构建体进行的进一步缺失分析表明， - 398 / - 289区域也具有增强子活性，尽管在神经索和内胚层前体细胞中检测到异位报告基因表达。 - 398 / - 289区域有一个Zic结合位点，它对增强子活性也是必不可少的。这些结果表明，Ets和Zic结合位点对H r - B r a表达的起始至关重要。总之，来自外源性和内源性因子的信息通过转录因子与增强子区域的直接结合在靶基因的增强子水平上被整合。（c）2007爱思唯尔公司。保留所有权利。
Extrinsic fibroblast growth factor (FGF) signal and intrinsic factors that determine the response of the signal-receiving blastomeres to FGF regulate mesoderm patterning in embryos of the ascidian Halocynthia roretzi. To investigate how cells integrate information from extrinsic and intrinsic inputs, we examined Brachyury (Hr-Bra) promoter activity in the early embryo. Hr-Bra, which encodes a key transcription factor for notochord development, is expressed exclusively in notochord precursors in a manner dependent on the FGF-MEK-MAPK-Ets signaling pathway and on the intrinsic factors Zic and FoxA. Reporter gene expression driven by the 900-bp upstream region of the Hr-Bra promoter was detected as early as the 110-cell stage in notochord precursors by in situ hybridization with a LacZ probe. Deletion analysis combined with MEK inhibitor treatment demonstrated that the -598/-499 region carries FGF-responsiveness. Electrophoretic mobility shift assay identified three Ets-binding sites in this region that were required for promoter activity. Further deletion analysis conducted by injecting eggs with reporter constructs at higher concentration suggested that the -398/-289 region also has enhancer activity, although ectopic reporter expression was detected in nerve cord and endoderm precursors. The -398/-289 region has a Zic-binding site that was also essential for the enhancer activity. These results indicate that Ets and Zic-binding sites are critical for the initiation of Hr-Bra expression. In conclusion, information from both extrinsic and intrinsic factors is integrated at the level of enhancer of the target gene by direct binding of the transcription factors to the enhancer region. (c) 2007 Elsevier Inc. All rights reserved.