Laboratory of Molecular Vertebrate Embryology, The Rockefeller University, New York, NY, USA.
EMBO J. 2011 Jan 19;30(2):237-48. doi: 10.1038/emboj.2010.319. Epub 2010 Dec 10.
Multiple levels of control are in play to regulate pluripotency and differentiation in human embryonic stem cells (hESCs). At the transcriptional level, the core factors OCT4, NANOG and SOX2 form a positive autoregulatory loop that is pivotal for maintaining the undifferentiated state. At the post-transcriptional level, microRNAs (miRNAs) belonging to the miR-302 family are emerging as key players in the control of proliferation and cell fate determination during differentiation. Here, we show that the transcriptional factors OCT4 and NR2F2 (COUP-TFII) and the miRNA miR-302 are linked in a regulatory circuitry that critically regulate both pluripotency and differentiation in hESCs. In the undifferentiated state, both OCT4 and the OCT4-induced miR-302 directly repress NR2F2 at the transcriptional and post-transcriptional level, respectively. Conversely, NR2F2 directly inhibits OCT4 during differentiation, triggering a positive feedback loop for its own expression. In addition, we show that regulation of NR2F2 activity itself relies on alternative splicing and transcriptional start site choice to generate a full-length transcriptionally active isoform and shorter variants, which enhance the activity of the long isoform. During hESC differentiation, NR2F2 is first detected at the earliest steps of neural induction and thus is among the earliest human embryonic neural markers. Finally, our functional analysis points to a crucial role for NR2F2 in the activation of neural genes during early differentiation in humans. These findings introduce a new molecular player in the context of early embryonic stem cell state and cell fate determination in humans.
多种调控机制在发挥作用以调节人类胚胎干细胞(hESC)的多能性和分化。在转录水平上,核心因子 OCT4、NANOG 和 SOX2 形成一个正反馈回路,对于维持未分化状态至关重要。在转录后水平上,miR-302 家族的 microRNAs(miRNAs)作为在分化过程中控制增殖和细胞命运决定的关键因子而出现。在这里,我们表明转录因子 OCT4 和 NR2F2(COUP-TFII)以及 miRNA miR-302 形成一个调控回路,该回路对于 hESC 的多能性和分化都具有重要的调控作用。在未分化状态下,OCT4 和 OCT4 诱导的 miR-302 分别在转录和转录后水平上直接抑制 NR2F2。相反,NR2F2 在分化过程中直接抑制 OCT4,触发其自身表达的正反馈回路。此外,我们表明 NR2F2 活性的调节本身依赖于选择性剪接和转录起始位点选择,以产生全长转录活性的异构体和较短的变体,从而增强长异构体的活性。在 hESC 分化过程中,NR2F2 最早在神经诱导的最早步骤中被检测到,因此是最早的人类胚胎神经标志物之一。最后,我们的功能分析表明 NR2F2 在人类早期分化过程中激活神经基因中起着至关重要的作用。这些发现为人类早期胚胎干细胞状态和细胞命运决定的背景下引入了一个新的分子参与者。