中文摘要：

DNA 甲基化是一种十分重要的表观遗传修饰，与转座元件沉默、基因组印记以及X染色体失活等多种生物学过程相关。胚胎特异性转录因子的表达可以将已经分化的小鼠（Mus musculus）成纤维细胞重编程为诱导多能干细胞（iPSCs）。由于在重编程过程中还伴随着一系列的表观遗传修饰变化，iPSCs 可作为研究表观遗传特点的有利工具，用来研究表观遗传修饰的相互作用及其动态学过程。本研究中，从35 d的猪（Sus scrofa）胎儿分离出胎儿成纤维细胞（PFF），使用经典的4因子组合，即Oct4、Sox2、Klf4和c-Myc 将PFF重编程为iPSCs，并进行了多能标记的染色，结果表明，所得到的克隆呈现OCT4、SOX2、NANOG和SSEA1阳性结果。采用亚硫酸氢盐测序法对内源性多能性相关基因Oct4、Sox2、Klf4、c-Myc 的启动子区域甲基化进行了检测，发现其启动子甲基化程度很低，表明体细胞重编程为iPSCs的过程伴随着多能基因启动子甲基化程度的降低，为理解iPS重编程中多能性相关基因的DNA去甲基化过程和了解控制多能性相关基因的表观遗传调节提供基础。

英文摘要：

DNA methylation is one of the most important epigenetic markers, which has been well characterized and demonstrated to be involved in many biological processes, including transposable element silencing, genomic imprinting and X chromosome inactivation etc. Yamanaka reprogrammed the mouse（Mus musculus） fibroblasts back to a pluripotent state via ectopically expressing four embryonically special transcription factors Oct4, Sox2, Klf4 and c-Myc, and named the cells as induced pluripotent stem cells （iPSCs）. During reprogramming, there was accompanied with a series of epigenetic changes, so iPSCs can be used as a useful tool to study the interplay of epigenetic modifications and dynamics. In this study, porcine（Sus scrofa） fetal fibroblasts were isolated from 35-day-old fetus, and were reprogrammed into iPSCs using classical four factors recombination, namely Oct4, Sox2, Klf4 and c-Myc. The pluripotent markers of colonies were identified by immunofluorescence staining. With the method of bisulphate treatment, methylation status of promoters in endogenous pluripotent genes Oct4, Sox2, Klf4 and c-Myc were detected. It was found that the methylation status were very low which indicated that it was accompanied by decreased methylation status in promoters during the reprogramming of somatic cells into iPSCs. Therefore, this study is helpful to understand the DNA demethylation of pluripotency gene, and provides further insight into epigenetic regulations that control the pluripotency genes expression during reprogramming.