Reciprocal transcriptional regulation of Pou5f1 and Sox2 via the Oct4/Sox2 complex in embryonic stem cells
Reciprocal transcriptional regulation of Pou5f1 and Sox2 via the Oct4/Sox2 complex in embryonic stem cells
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DOI：
10.1128/mcb.25.14.6031-6046.2005
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发表时间：
2005-07-01
影响因子：
5.3
通讯作者：
Ng, HH
中科院分区：
文献类型：
--
作者：
Chew, JL;Loh, YH;Ng, HH
胚胎干细胞（ESCs）是多能细胞，它们既能自我更新，也能分化为多种细胞类型。Oct4和Sox2是对胚胎干细胞的多能性和自我更新表型至关重要的转录因子。这两种因子在转录调控网络层级中处于上游，并且是调控若干胚胎干细胞特异性基因的伙伴。在胚胎干细胞中，Sox2受到一个含有复合sox - oct元件的增强子的转录调控，Oct4和Sox2以一种组合相互作用的方式结合到该元件上。先前已表明，Oct4基因Pou5f1包含一个远端增强子，该增强子在胚胎干细胞和着床前胚胎中都赋予特异性表达。在此，我们在这个增强子中鉴定出一个复合sox - oct元件，并表明它参与胚胎干细胞中Pou5f1的转录活性。利用胚胎干细胞核提取物进行的体外实验证明，Oct4和Sox2与这个调控元件特异性相互作用。更重要的是，通过染色质免疫沉淀分析，我们确定在活的小鼠和人类胚胎干细胞中，Oct4和Sox2都直接结合到Pou5f1和Sox2中的复合sox - oct元件上。通过RNA干扰对Oct4或Sox2进行特异性敲低，除了导致胚胎干细胞分化外，还会使这两个基因的增强子活性以及内源性表达水平降低。我们的数据揭示了一个正向且可能具有自我强化作用的调控环路，该环路通过Oct4/Sox2复合物在多能细胞中维持Pou5f1和Sox2的表达。
Embryonic stem cells (ESCs) are pluripotent cells that can either self-renew or differentiate into many cell types. Oct4 and Sox2 are transcription factors essential to the pluripotent and self-renewing phenotypes of ESCs. Both factors are upstream in the hierarchy of the transcription regulatory network and are partners in regulating several ESC-specific genes. In ESCs, Sox2 is transcriptionally regulated by an enhancer containing a composite sox-oct element that Oct4 and Sox2 bind in a combinatorial interaction. It has previously been shown that Pou5f1, the Oct4 gene, contains a distal enhancer imparting specific expression in both ESCs and preimplantation embryos. Here, we identify a composite sox-oct element within this enhancer and show that it is involved in Pou5f1 transcriptional activity in ESCs. In vitro experiments with ESC nuclear extracts demonstrate that Oct4 and Sox2 interact specifically with this regulatory element. More importantly, by chromatin immunoprecipitation assay, we establish that both Oct4 and Sox2 bind directly to the composite sox-oct elements in both Pou5f1 and Sox2 in living mouse and human ESCs. Specific knockdown of either Oct4 or Sox2 by RNA interference leads to the reduction of both genes' enhancer activities and endogenous expression levels in addition to ESC differentiation. Our data uncover a positive and potentially self-reinforcing regulatory loop that maintains Pou5f1 and Sox2 expression via the Oct4/Sox2 complex in pluripotent cells.