Department of Stem Cell Engineering, Institute for Frontier Medical Sciences, Kyoto University, Kyoto 606-8507, Japan.
Department of Reprogramming Science, Center for iPS Cell Research and Application, Kyoto University, Kyoto, 606-8507, Japan.
Dev Biol. 2014 Aug 15;392(2):182-92. doi: 10.1016/j.ydbio.2014.06.002. Epub 2014 Jun 12.
Nanog, a core pluripotency factor, is required for stabilizing pluripotency of inner cell mass (ICM) and embryonic stem cells (ESCs), and survival of primordial germ cells in mice. Here, we have addressed function and regulation of Nanog in epiblasts of postimplantation mouse embryos by conditional knockdown (KD), chromatin immunoprecipitation (ChIP) using in vivo epiblasts, and protein interaction with the Nanog promoter in vitro. Differentiation of Nanog-KD epiblasts demonstrated requirement for Nanog in stabilization of pluripotency. Nanog expression in epiblast is directly regulated by Nodal/Smad2 pathway in a visceral endoderm-dependent manner. Notably, Nanog promoters switch from Oct4/Esrrb in ICM/ESCs to Oct4/Smad2 in epiblasts. Smad2 directly associates with Oct4 to form Nanog promoting protein complex. Collectively, these data demonstrate that Nanog plays a key role in stabilizing Epiblast pluripotency mediated by Nodal/Smad2 signaling, which is involved in Nanog promoter switching in early developing embryos.
Nanog 是多能性的核心因子之一，对于维持内细胞团（ICM）和胚胎干细胞（ESCs）的多能性以及小鼠原始生殖细胞的存活是必需的。在这里，我们通过条件性敲低（KD）、体内上胚层的染色质免疫沉淀（ChIP）以及体外与 Nanog 启动子的蛋白相互作用，研究了 Nanog 在植入后小鼠胚胎上胚层中的功能和调控。分化的 Nanog-KD 上胚层证明 Nanog 对于多能性的稳定是必需的。Nanog 在上胚层中的表达受到 Nodal/Smad2 通路的直接调控，以内胚层依赖性的方式进行。值得注意的是，Nanog 启动子在上胚层中从 ICM/ESCs 中的 Oct4/Esrrb 切换到了 Epiblasts 中的 Oct4/Smad2。Smad2 直接与 Oct4 结合形成促进 Nanog 的蛋白复合物。总的来说，这些数据表明 Nanog 在由 Nodal/Smad2 信号介导的上胚层多能性稳定中发挥关键作用，这涉及到早期胚胎中 Nanog 启动子的切换。
