体细胞核重编程中Xist基因表达沉默、组蛋白H3K27me3甲基化擦除与X染色体重新激活密切相关，而KDM6B是H3K27me3去甲基化特异酶。本研究拟建立牛KDM6B基因超表达成纤维细胞系，并采用CRISPR-CAS9技术编辑Xist基因，探讨KDM6B基因超表达，及Xist基因沉默后对细胞全基因组DNA甲基化水平，组蛋白甲基化(H3K27me3，H3K9me1/2/3)，X染色体激活相关基因表达(基因微阵列分析)水平的影响；然后将OSKM四因子导入进行KDM6B-IPS多能干细胞诱导，研究KDM6B基因超表达，Xist基因沉默对细胞核体外重编程效率及X染色体重塑状态(RNA-FISH法)的影响，最后将细胞构建重组胚胎，探究KDM6B超表达对胚胎重编程，胚胎组蛋白甲基化水平和X染色体重塑状态影响，从细胞和胚胎水平上初步阐明KDM6B基因超表达，Xist基因沉默与X染色体重塑间的相关关系。

There was a close relationship between the demethylation of H3K27me3 and down-regulation expression of Xist gene with reactivation of X chromosome during the reprogramming of nucleus in somatic cell nuclear transfer or induction of induced pluripotent stem cells in Vitro, and we know that the KDM6B gene is a specific H3K27me3 demethylation enzyme. In this study,KDM6B gene over-expression bovine fibroblast cells were generated, and combined with Xist gene knockdown (knockout) by CRISPR-CAS9 genome editing method in this cell line at same time. following this cells was induced by Doxycycline, the genome wild DNA methylation levels , histone methylation levels (H3K27me3 and H3K9me1/2/3) and X chromosome reactivation related genes expression micro-array analysis were detected in this KDM6B over-expression and Xist gene knockdown (knockout) cells.When OSKM 4 factors were introduced into these cells,the efficiencies of KDM6B-IPS colonies formation and status of X chromosome reactivation were analysis(RNA-FISH method).Lastly,KDM6B over-expression and Xist gene knockdown (knockout) bovine fibroblast cells used as donors for nuclear transfer,the development of reconstructed bovine embryos were compared and the levels of histone methylation(H3K9me1/2/3, H3K27me3)and the status of X chromosome remodeling were detected in the blastocysts. Above of all, we try to elucidate the relationship between KDM6B over-expression and Xist gene knockdown (knock out) and X chromosome reactivation during nucleus reprogramming.