Han Dong Wook, Do Jeong Tae, Gentile Luca, Stehling Martin, Lee Hoon Taek, Schöler Hans R
Department of Cell and Developmental Biology, Max Planck Institute for Molecular Biomedicine, Röntgenstrasse 20, 48149 Münster, Germany.
Stem Cells. 2008 Feb;26(2):445-54. doi: 10.1634/stemcells.2007-0553. Epub 2007 Dec 6.
The fusion of pluripotent embryonic cells with somatic cells results in reprogramming of the somatic cell genome. Oct4-green fluorescent protein (GFP) transgenes that do not contain the proximal enhancer (PE) region are widely used to visualize reprogramming of the somatic to the pluripotent cell state. The temporal onset of Oct4-GFP activation has been found to occur 40-48 hours postfusion. We asked whether activation of the transgene actually reflects activation of the endogenous Oct4 gene. In the current study, we show that activation of an Oct4-GFP transgene that contains the PE region occurs within 22 hours of fusion. In addition, demethylation of the Oct4-GFP transgene and that of the endogenous Oct4 and Nanog genes was found to occur within 24 hours of fusion. As this timing corresponds with the timing of cell cycle completion in embryonic stem cells and fusion hybrids (approximately 22 hours), we postulate that pluripotential reprogramming of the somatic cell genome begins during the first cell cycle after the fusion of a somatic cell with a pluripotent cell and has been completed by day 2 postfusion.
多能胚胎细胞与体细胞的融合导致体细胞基因组重编程。不含近端增强子（PE）区域的Oct4-绿色荧光蛋白（GFP）转基因被广泛用于观察体细胞向多能细胞状态的重编程。已发现Oct4-GFP激活的时间起始发生在融合后40-48小时。我们询问转基因的激活是否实际上反映了内源性Oct4基因的激活。在当前研究中，我们表明包含PE区域的Oct4-GFP转基因在融合后22小时内发生激活。此外，发现Oct4-GFP转基因以及内源性Oct4和Nanog基因的去甲基化在融合后24小时内发生。由于这个时间与胚胎干细胞和融合杂种细胞周期完成的时间（约22小时）相对应，我们推测体细胞基因组的多能性重编程在体细胞与多能细胞融合后的第一个细胞周期期间开始，并在融合后第2天完成。
