Massachusetts General Hospital Cancer Center and Center for Regenerative Medicine, 185 Cambridge Street, Boston, MA 02114, USA.
Cell. 2012 Dec 21;151(7):1617-32. doi: 10.1016/j.cell.2012.11.039.
Factor-induced reprogramming of somatic cells into induced pluripotent stem cells (iPSCs) is inefficient, complicating mechanistic studies. Here, we examined defined intermediate cell populations poised to becoming iPSCs by genome-wide analyses. We show that induced pluripotency elicits two transcriptional waves, which are driven by c-Myc/Klf4 (first wave) and Oct4/Sox2/Klf4 (second wave). Cells that become refractory to reprogramming activate the first but fail to initiate the second transcriptional wave and can be rescued by elevated expression of all four factors. The establishment of bivalent domains occurs gradually after the first wave, whereas changes in DNA methylation take place after the second wave when cells acquire stable pluripotency. This integrative analysis allowed us to identify genes that act as roadblocks during reprogramming and surface markers that further enrich for cells prone to forming iPSCs. Collectively, our data offer new mechanistic insights into the nature and sequence of molecular events inherent to cellular reprogramming.
体细胞经诱导重编程为诱导多能干细胞（iPSCs）的效率较低，这使得机制研究变得复杂。在这里，我们通过全基因组分析检查了处于成为 iPSCs 状态的定义明确的中间细胞群体。我们表明，诱导多能性引发了两个转录波，这两个转录波由 c-Myc/Klf4（第一波）和 Oct4/Sox2/Klf4（第二波）驱动。对重新编程产生抗性的细胞会激活第一波，但无法启动第二波转录，并且可以通过提高这四个因子的表达来挽救。在第一波之后，双价域的建立逐渐发生，而在第二波之后，当细胞获得稳定的多能性时，DNA 甲基化才会发生变化。这种综合分析使我们能够鉴定在重编程过程中起阻碍作用的基因，以及进一步富集易于形成 iPSCs 的细胞的表面标志物。总的来说，我们的数据为细胞重编程所固有的分子事件的本质和顺序提供了新的机制见解。
