Laboratory of Animal Breeding, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan.
Endocrinology. 2010 Dec;151(12):5873-81. doi: 10.1210/en.2010-0458. Epub 2010 Oct 20.
The transcription factor caudal-related homeobox 2 (CDX2) regulates trophectoderm differentiation, but its function beyond trophectoderm differentiation is not well characterized. CDX2 was shown to regulate a trophoblast-specific gene, interferon τ (IFNT), in the ruminants. However, its regulatory mechanism has not been determined. Here, we report a new role of CDX2 in histone modifications of the IFNT gene. Chromatin immunoprecipitation assays using ovine conceptuses obtained from d 14, 16, 16.5, or 20 of pregnancy (d 0, day of mating) revealed that H3K18 acetylation was highly detectable at the upstream and open reading frame regions of the IFNT gene on d 14 and 16, when CDX2 reached its peak expression. From d 16.5, when the conceptus initiates attachment to uterine epithelial cells, histone acetylation along with CDX2 expression declines. Two candidate CDX2 binding sites (-300 to -294 bp and -293 to -287 bp) of the bovine IFNT gene promoter region were detected from chromatin immunoprecipitation and luciferase assay. When Cdx2 constructs were transfected into bovine ear-derived fibroblast cells, histone acetylation was increased, concurrent with the recruitment of cAMP response element binding protein-binding protein, which has histone acetyltransferase activity. H3K18 acetylation was seen in the proximity of the CDX2 binding region located at the IFNT gene's upstream region in CT-1 cells, but when these cells were treated with specific CDX2 small interfering RNA, H3K18 acetylation was decreased. These findings suggest that CDX2 regulates its targeted gene through cAMP response element binding protein-binding protein recruitment, which correlates with greater histone acetylation.
同源盒蛋白 2（CDX2）是一种转录因子，可调节滋养外胚层的分化，但它在滋养外胚层分化之外的功能尚未得到很好的描述。在反刍动物中，CDX2 被证明可以调节一种滋养层特异性基因，即干扰素 τ（IFNT）。然而，其调控机制尚未确定。在这里，我们报道了 CDX2 在 IFNT 基因的组蛋白修饰中的一个新作用。使用来自妊娠 14、16、16.5 或 20 天（交配后第 0 天）的绵羊胚胎获得的概念进行染色质免疫沉淀分析显示，在 CDX2 表达峰值的第 14 天和第 16 天，IFNT 基因的上游和开放阅读框区域高度检测到 H3K18 乙酰化。从第 16.5 天开始，当胚胎开始附着到子宫上皮细胞时，与 CDX2 表达一起，组蛋白乙酰化下降。在牛 IFNT 基因启动子区域检测到两个候选的 CDX2 结合位点（-300 至-294 bp 和-293 至-287 bp），通过染色质免疫沉淀和荧光素酶检测。当 Cdx2 构建体转染到牛耳源性成纤维细胞中时，组蛋白乙酰化增加，同时募集了具有组蛋白乙酰转移酶活性的 cAMP 反应元件结合蛋白结合蛋白。在 CT-1 细胞中，在 IFNT 基因上游区域的 CDX2 结合区域附近观察到 H3K18 乙酰化，但当这些细胞用特异性 CDX2 小干扰 RNA 处理时，H3K18 乙酰化减少。这些发现表明，CDX2 通过募集 cAMP 反应元件结合蛋白结合蛋白来调节其靶基因，这与更大的组蛋白乙酰化相关。
