Differential regulation of intestinal alkaline phosphatase gene expression by Cdx1 and Cdx2
Differential regulation of intestinal alkaline phosphatase gene expression by Cdx1 and Cdx2
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DOI：
10.1152/ajpgi.00037.2005
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发表时间：
2005-08-01
影响因子：
4.5
通讯作者：
Hodin, RA
中科院分区：
文献类型：
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作者：
Alkhoury, F;Malo, MS;Hodin, RA
Cdx1和cdx2对肠道碱性磷酸酶基因表达的差异调控。Am J Physiol胃肠病肝生理学289：G285-G290,2005.2005年3月17日首次出版；DOI：10.1152/ajpgi.00037.2005。-我们研究了尾部相关的同源盒转录因子CDX1和CDX2在激活肠道细胞分化标志基因肠道碱性磷酸酶(IAP)中所起的作用。将CDX1和/或CDX2瞬时导入人结肠癌Caco-2细胞，用半定量RT-PCR方法检测其对IAP基因表达的影响。用不同的IAP-荧光素酶报告结构的转基因来鉴定位于人IAP基因启动子内的CDX反应元件。EMSA检测蛋白质与DNA的相互作用。结果表明，Cdx1能显著诱导IAP基因的表达，而Cdx2不能诱导IAP基因的表达，并能抑制其作用。功能分析表明，CDX1通过位于翻译起始点上游-2369和-2375之间的一个新的CDX反应元件(GTTTAGA)反式激活IAP启动子(4倍，P<；0.05)。EMSA显示，CDX1和CDX2都能与顺式元件结合，但在共转染实验中，CDX2对CDX1的抑制作用类似于50%。因此，在IAP基因调控的背景下，我们发现了两个重要的肠道转录因子CDX1和CDX2之间以前未被发现的相互作用。Cdx1通过一个新的顺式元件激活IAP基因，而Cdx2抑制Cdx1的作用。
Differential regulation of intestinal alkaline phosphatase gene expression by Cdx1 and Cdx2. Am J Physiol Gastrointest Liver Physiol 289:G285-G290, 2005. First published March 17, 2005; doi:10.1152/ajpgi.00037.2005.-We have examined the role that the caudal-related homeobox transcription factors Cdx1 and Cdx2 play in activating the enterocyte differentiation marker gene intestinal alkaline phosphatase (IAP). Human colon cancer Caco-2 cells were transiently transfected with Cdx1 and/or Cdx2, and semiquantitative RT-PCR was used to study the effects on IAP mRNA expression. Transfections with a variety of IAP-luciferase reporter constructs were used to identify a Cdx response element located within the human IAP gene promoter. Protein-DNA interactions were examined by EMSA. Results showed that Cdx1 markedly induced IAP mRNA expression, whereas Cdx2 did not, and, in fact, inhibited the Cdx1 effects. Functional analysis revealed that Cdx1 transactivates ( fourfold, P < 0.05) the IAP promoter through a novel Cdx response element (GTTTAGA) located between -2369 and -2375 upstream of the translational start site. EMSA showed that both Cdx1 and Cdx2 could bind to the cis element, but in cotransfection experiments, Cdx2 inhibited the Cdx1 effects by similar to 50%. Thus we have identified a previously unrecognized interaction between two important gut transcription factors, Cdx1 and Cdx2, in the context of IAP gene regulation. Cdx1 activates the IAP gene via a novel cis element, whereas Cdx2 inhibits the Cdx1 effects.