AgResearch Crown Research Institute, Hamilton, 3214, New Zealand.
Dev Biol. 2011 Dec 15;360(2):343-50. doi: 10.1016/j.ydbio.2011.10.007. Epub 2011 Oct 12.
Mouse Elf5 is expressed exclusively in the trophectoderm from the late blastocyst stage to postgastrulation. We demonstrate here that the proximal promoter is used for trophectoderm expression but is not sufficient on its own. In transgenic assays, deletion of a differentially methylated region (DMR) within the promoter has no effect on the activation and maintenance of trophectoderm expression and does not result in ectopic activity. Two redundant enhancers drive Elf5 expression to the extraembryonic ectoderm and ectoplacental cone. The enhancers, located in the 5' half of intron 1 and 3' half of intron 2, require the presence of 1.8kbp, although not the DMR, of the endogenous proximal promoter for optimal activity. These trophectoderm enhancers are mouse specific. A cattle Elf5 BAC reporter transgene is not expressed in mouse trophectoderm although it is expressed in skin, a known foetal domain of mouse Elf5 expression. The established importance of Elf5 for mouse trophectoderm at pre- and perigastrulation stages is not a conserved mammalian feature as Elf5 expression localises to embryonic as opposed to trophectodermal ectoderm in cattle.
鼠 Elf5 仅在囊胚晚期至原肠胚后期的滋养外胚层中表达。我们在此证明，近端启动子用于滋养外胚层表达，但本身并不足够。在转基因分析中，启动子内差异甲基化区域 (DMR) 的缺失对滋养外胚层表达的激活和维持没有影响，也不会导致异位活性。两个冗余增强子驱动 Elf5 表达到胚胎外胚层和胎盘外腔。这些位于内含子 1 的 5' 端和内含子 2 的 3' 端的增强子需要内源性近端启动子的 1.8kbp 存在，尽管不是 DMR，以发挥最佳活性。这些滋养外胚层增强子是小鼠特异性的。牛 Elf5 BAC 报告基因转基因在小鼠滋养外胚层中不表达，尽管它在皮肤中表达，皮肤是小鼠 Elf5 表达的已知胎儿区域。在原肠胚前期和后期，Elf5 对小鼠滋养外胚层的重要性不是哺乳动物的保守特征，因为在牛中，Elf5 表达定位于胚胎外胚层而不是滋养外胚层。
