State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, PR China.
State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, PR China.
Theriogenology. 2019 Jul 1;132:95-105. doi: 10.1016/j.theriogenology.2019.04.007. Epub 2019 Apr 14.
The EZH2 protein endows the polycomb repressive complex 2 (PRC2) with histone lysine methyltransferase activity that is associated with transcriptional repression. Recent investigations have documented crucial roles for EZH2 in mediating X-inactivation, stem cell pluripotency and cancer metastasis. However, there is little evidence demonstrating the maternal effect of EZH2 on porcine preimplantation development. Here, we took parthenogenetic activation embryos to eliminate the confounding paternal influence. We showed that the dynamic expression of EZH2 during early development was accompanied by changes in H3K27me3 levels. Depletion of EZH2 in MII oocytes by small interfering RNA not only impaired embryonic development at the blastocyst stage (P < 0.05), but also disrupted the equilibrium of H3K4me3 and H3K27me3 in the embryo. Interestingly, the expression of TET1, a member of Ten-Eleven Translocation gene family for converting 5-methylcytosine (5 mC) to 5-hydroxymethylcytosine (5hmC), was decreased after EZH2 knockdown, in contrast to the increase of the other two members, TET2 and TET3 (P < 0.05). These results indicate a correlation between histone methylation and DNA methylation, and between EZH2 and TET1. Along with the downregulation of TET1, the expression of the pluripotency gene NANOG was decreased (P < 0.05), which is consistent with a previous finding in mouse ES cells. Meanwhile, the abundance of OCT4 and SOX2 were also down-regulated. Moreover, EZH2 knockdown reduced the capacity of cells in the blastocysts to resist apoptosis. Taken together, our data suggest that EZH2 is integral to the developmental program of porcine parthenogenetic embryos and exerts its function by regulating pluripotency, differentiation and apoptosis.
EZH2 蛋白赋予多梳抑制复合物 2(PRC2)组蛋白赖氨酸甲基转移酶活性,与转录抑制有关。最近的研究表明,EZH2 在介导 X 染色体失活、干细胞多能性和癌症转移中起着至关重要的作用。然而,几乎没有证据表明 EZH2 对猪胚胎植入前发育有母源性影响。在这里,我们采用孤雌激活胚胎来消除父本的混杂影响。结果表明,EZH2 在早期发育过程中的动态表达伴随着 H3K27me3 水平的变化。用小干扰 RNA 耗竭 MII 卵母细胞中的 EZH2 不仅损害了囊胚阶段的胚胎发育(P < 0.05),而且破坏了胚胎中 H3K4me3 和 H3K27me3 的平衡。有趣的是,EZH2 敲低后,Ten-Eleven Translocation 基因家族成员 TET1 的表达减少,而另两个成员 TET2 和 TET3 的表达增加(P < 0.05)。这些结果表明组蛋白甲基化与 DNA 甲基化之间存在相关性,EZH2 与 TET1 之间也存在相关性。随着 TET1 的下调,多能基因 NANOG 的表达也降低(P < 0.05),这与以前在小鼠 ES 细胞中的发现一致。同时,OCT4 和 SOX2 的丰度也下调。此外,EZH2 敲低降低了囊胚细胞抵抗凋亡的能力。综上所述,我们的数据表明,EZH2 是猪孤雌胚胎发育程序的重要组成部分,通过调节多能性、分化和凋亡来发挥其功能。