Multiple regulatory regions control the complex expression pattern of the mouse Cdx2 homeobox gene
Multiple regulatory regions control the complex expression pattern of the mouse Cdx2 homeobox gene
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DOI：
10.1053/j.gastro.2008.06.045
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发表时间：
2008-10-01
期刊：
影响因子：
29.4
通讯作者：
Duluc, Isabelle
中科院分区：
文献类型：
--
作者：
Benahmed, Fairouz;Gross, Isabelle;Duluc, Isabelle
背景和目标：Cdx 2同源异型盒基因发挥多种功能，包括滋养外胚层的规范，前后图案，并确定肠道的身份。这项研究的目的是绘制调控Cdx 2转录的基因组区域，特别是在肠道中。方法：在转基因小鼠和细胞测定中分析了覆盖小鼠Cdx 2基因座13千碱基（kb）的基因组片段。结果：在滋养外胚层中没有活性片段。含有第一个内含子并延伸至转录起始位点上游约5 kb的片段在原肠胚形成时变得活跃，然后在妊娠中期在包括内胚层在内的每个组织中变得不活跃。在妊娠中期之后肠内胚层/上皮中活性的特异性持久性需要将基因组片段延伸至约9 kb。我们鉴定了约8.5kb的250个碱基对片段，其结合并响应于内胚层因子，具有由HNF 4 α、GATA 6、Tcf 4和β-连环蛋白协同发挥的刺激作用。这些因素能够激活内源性表达的Cdx 2在非肠道Hela细胞。结论：多个调控区域控制Cdx 2的复杂发育模式，包括在整个生命过程中特异性地在肠道上皮中持续基因表达所需的远上游序列。HNF 4 α、GATA 6、β-连环蛋白和Tcf 4之间的合作有助于Cdx 2的丝氨酸特异性表达。
Background & Aims: The Cdx2 homeobox gene exerts multiple functions including trophectoderm specification, antero-posterior patterning, and determination of intestinal identity. The aim of this study was to map genomic regions that regulate the transcription of Cdx2, with a particular interest in the gut. Methods: Genomic fragments covering 13 kilobase (kb) of the mouse Cdx2 locus were analyzed in transgenic mice and in cell assays. Results: No fragment was active in the trophectoderm. Fragments containing the first intron and extending up to -5-kb upstream of the transcription start site became active posteriorly at gastrulation and then inactive at midgestation in every tissue including the endoderm. Specific persistence of activity in the intestinal endoderm/epithelium beyond midgestation requires extending the genomic fragment up to -9 kb. We identified a 250-base pair segment around -8.5-kb binding and responding to endodermal factors, with a stimulatory effect exerted synergistically by HNF4 alpha, GATA6, Tcf4, and beta-catenin. These factors were able to activate endogenous expression of Cdx2 in nonintestinal Hela cells. Conclusions: Multiple regulatory regions control the complex developmental pattern of Cdx2, including far upstream sequences required for the persistence of gene expression specifically in the gut epithelium throughout life. Cooperation between HNF4 alpha, GATA6, beta-catenin, and Tcf4 contributes to the intestine-specific expression of Cdx2.