CAS Key Laboratory of Regenerative Biology, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China.
Nat Cell Biol. 2013 Jul;15(7):829-38. doi: 10.1038/ncb2765. Epub 2013 May 26.
Present practices for reprogramming somatic cells to induced pluripotent stem cells involve simultaneous introduction of reprogramming factors. Here we report that a sequential introduction protocol (Oct4-Klf4 first, then c-Myc and finally Sox2) outperforms the simultaneous one. Surprisingly, the sequential protocol activates an early epithelial-to-mesenchymal transition (EMT) as indicated by the upregulation of Slug and N-cadherin followed by a delayed mesenchymal-to-epithelial transition (MET). An early EMT induced by 1.5-day TGF-β treatment enhances reprogramming with the simultaneous protocol, whereas 12-day treatment blocks reprogramming. Consistent results were obtained when the TGF-β antagonist Repsox was applied in the sequential protocol. These results reveal a time-sensitive role of individual factors for optimal reprogramming and a sequential EMT-MET mechanism at the start of reprogramming. Our studies provide a rationale for further optimizing reprogramming, and introduce the concept of a sequential EMT-MET mechanism for cell fate decision that should be investigated further in other systems, both in vitro and in vivo.
目前将体细胞重编程为诱导多能干细胞的方法涉及同时引入重编程因子。在这里，我们报告说，顺序引入方案（首先是 Oct4-Klf4，然后是 c-Myc 和 Sox2）优于同时引入方案。令人惊讶的是，顺序方案会激活早期上皮-间充质转化（EMT），表现为 Slug 和 N-钙黏蛋白的上调，随后是延迟的间充质-上皮转化（MET）。用 1.5 天 TGF-β处理诱导的早期 EMT 增强了同时引入方案的重编程，而 12 天的处理则阻断了重编程。在顺序方案中应用 TGF-β拮抗剂 Repsox 时，得到了一致的结果。这些结果揭示了个体因素对于最佳重编程的时间敏感性作用，以及在重编程开始时的顺序 EMT-MET 机制。我们的研究为进一步优化重编程提供了依据，并提出了一个顺序 EMT-MET 机制的概念，用于细胞命运决定，这应该在其他系统中进一步研究，包括体外和体内。
