Faculty of Life Sciences and Institutes for Protein Dynamics and Comprehensive Research, Kyoto Sangyo University, Kyoto, Japan.
Institute of Advanced Medical Sciences, Tokushima University, Tokushima, Japan.
Genes Cells. 2020 Apr;25(4):242-256. doi: 10.1111/gtc.12753. Epub 2020 Feb 26.
The transcription factor (TF) SOX2 regulates various stem cells and tissue progenitors via functional interactions with cell type-specific partner TFs that co-bind to enhancer sequences. Neural progenitors are the major embryonic tissues where SOX2 assumes central regulatory roles. In order to characterize the partner TFs of SOX2 in neural progenitors, we investigated the regulation of the D1 enhancer of the Sox2 gene, which is activated in the embryonic neural tube (NT) and neural crest (NC), using chicken embryo electroporation. We identified essential TF binding sites for a SOX, and two ZIC TFs in the activation of the D1 enhancer. By comparison of dorso-ventral and antero-posterior patterns of D1 enhancer activation, and the effect of mutations on the enhancer activation patterns with TF expression patterns, we determined SOX2 and ZIC2 as the major D1 enhancer-activating TFs. Binding of these TFs to the D1 enhancer sequence was confirmed by chromatin immunoprecipitation analysis. The combination of SOX2 and ZIC2 TFs activated the enhancer in both the NT and NC. These results indicate that SOX2 and ZIC2, which have been known to play major regulatory roles in neural progenitors, do functionally cooperate. In addition, the recently demonstrated SOX2 expression during the NC development is accounted for at least partly by the D1 enhancer activity. Deletion of the D1 enhancer sequence from the mouse genome, however, did not affect the mouse development, indicating functional redundancies of other enhancers.
转录因子（TF）SOX2 通过与细胞类型特异性伴侣 TF 的功能相互作用来调节各种干细胞和组织祖细胞，这些伴侣 TF 共同结合到增强子序列上。神经祖细胞是 SOX2 发挥核心调节作用的主要胚胎组织。为了研究 SOX2 在神经祖细胞中的伴侣 TF，我们利用鸡胚电穿孔技术研究了 Sox2 基因 D1 增强子的调控。该增强子在胚胎神经管（NT）和神经嵴（NC）中被激活。我们确定了 D1 增强子激活所必需的 SOX 和两个 ZIC TF 的 TF 结合位点。通过比较 D1 增强子激活的背腹和前后模式，以及突变对增强子激活模式与 TF 表达模式的影响，我们确定 SOX2 和 ZIC2 是 D1 增强子激活的主要 TF。通过染色质免疫沉淀分析证实了这些 TF 与 D1 增强子序列的结合。这些 TF 的结合激活了 NT 和 NC 中的增强子。这些结果表明，SOX2 和 ZIC2 在神经祖细胞中发挥主要调节作用，它们确实具有功能上的合作。此外，最近在 NC 发育过程中证明的 SOX2 表达至少部分由 D1 增强子活性解释。然而，从鼠基因组中删除 D1 增强子序列并没有影响鼠的发育，这表明其他增强子具有功能冗余性。
