Dax1 Binds to Oct3/4 and Inhibits Its Transcriptional Activity in Embryonic Stem Cells
Dax1 Binds to Oct3/4 and Inhibits Its Transcriptional Activity in Embryonic Stem Cells
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DOI：
10.1128/mcb.01863-08
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发表时间：
2009-08-15
影响因子：
5.3
通讯作者：
Yokota, Takashi
中科院分区：
文献类型：
--
作者：
Sun, Chuanhai;Nakatake, Yuhki;Yokota, Takashi
胚胎干（ES）细胞是源自囊胚内细胞团的多能细胞。转录因子Oct3/4是ES细胞自我更新不可缺少的因子。在这项研究中，我们寻找一种能够与 ES 细胞中的 Oct3/4 相互作用的蛋白质，并鉴定出一种孤儿核激素受体 Dax1。 Dax1 与 Oct3/4 的关联是通过 Oct3/4 的 POU 特异性结构域介导的。 Dax1 的异位表达抑制了 Oct3/4 介导的人工 Oct3/4 响应启动子的激活。 ES 细胞中 Dax1 的表达也降低了 Nanog 和 Rex1 启动子的活性，而 Dax1 的敲低则增加了这些活性。 Pulldown 和凝胶位移测定表明 Dax1 与 Oct3/4 的相互作用消除了 Oct3/4 的 DNA 结合活性。染色质免疫沉淀测定结果显示，Dax1 抑制 Oct3/4 与 Oct3/4 和 Nanog 启动子/增强子区域的结合。此外，Dax1 的过度表达导致 ES 细胞分化。综上所述，这些数据表明 Dax1（一种与 Oct3/4 相互作用的新型分子）在 ES 细胞中充当 Oct3/4 的负调节因子。
Embryonic stem (ES) cells are pluripotent cells derived from the inner cell mass of blastocysts. Transcription factor Oct3/4 is an indispensable factor in the self-renewal of ES cells. In this study, we searched for a protein that would interact with Oct3/4 in ES cells and identified an orphan nuclear hormone receptor, Dax1. The association of Dax1 with Oct3/4 was mediated through the POU-specific domain of Oct3/4. Ectopic expression of Dax1 inhibited Oct3/4-mediated activation of an artificial Oct3/4-responsive promoter. Expression of Dax1 in ES cells also reduced the activities of Nanog and Rex1 promoters, while knockdown of Dax1 increased these activities. Pulldown and gel shift assays revealed that the interaction of Dax1 with Oct3/4 abolished the DNA binding activity of Oct3/4. Chromatin immunoprecipitation assay results showed that Dax1 inhibited Oct3/4 binding to the promoter/enhancer regions of Oct3/4 and Nanog. Furthermore, overexpression of Dax1 resulted in ES cell differentiation. Taken together, these data suggest that Dax1, a novel molecule interacting with Oct3/4, functions as a negative regulator of Oct3/4 in ES cells.