Department of Animal Sciences, Chungbuk National University, Cheongju 361-763, South Korea.
Reprod Biol Endocrinol. 2013 Jul 18;11:69. doi: 10.1186/1477-7827-11-69.
Series of epigenetic events happen during preimplantation development. Therefore assistant reproduction techniques (ART) have the potential to disrupt epigenetic regulation during embryo development. The purpose of this study was to investigate whether defects in methylation patterns in blastocyst due to superovulation originate from abnormal expression of Dnmts.
Low- (6 IU) and high- (10 IU) dosage of PMSG was used to stimulate the female mice. The metaphase II(MII) oocytes, zygotes and blastocyst stage embryos were collected. Global methylation and methylation at H3K9 in zygote, and methylation at repeated sequence Line 1 and IAP in blastocysts were assayed. In addition, expression of Dnmts was examined in oocytes and zygotes.
Global DNA methylation and methylation at H3K9 in zygotes derived from females after low- or high-dosage hormone treatment were unaltered compared to that in controls. Moreover, DNA methylation at IAP in blastocysts was also unaffected, regardless of hormone dosage. In contrast, methylation at Line1 decreased when high-dose hormone was administered. Unexpectedly, expression of Dnmt3a, Dnmt3b, Dnmt3L as well as maintenance Dnmt1o in oocytes and zygotes was not disrupted.
The results suggest that defects in embryonic methylation patterns do not originate from the disruption of Dnmt expression.
一系列的表观遗传事件发生在胚胎着床前的发育过程中。因此，辅助生殖技术（ART）有可能在胚胎发育过程中破坏表观遗传调控。本研究的目的是研究由于超排卵导致囊胚中甲基化模式的缺陷是否源于 Dnmts 的异常表达。
用低剂量（6IU）和高剂量（10IU）PMSG 刺激雌性小鼠。收集中期 II（MII）卵母细胞、受精卵和囊胚期胚胎。检测受精卵中的整体甲基化和 H3K9 甲基化，以及囊胚中重复序列 Line1 和 IAP 的甲基化。此外，还检测了卵母细胞和受精卵中 Dnmts 的表达。
与对照组相比，低剂量或高剂量激素处理后的雌性来源的受精卵中的整体 DNA 甲基化和 H3K9 甲基化没有改变。此外，囊胚中 IAP 的 DNA 甲基化也不受激素剂量的影响。相反，当给予高剂量激素时，Line1 的甲基化减少。出乎意料的是，卵母细胞和受精卵中 Dnmt3a、Dnmt3b、Dnmt3L 以及维持 Dnmt1o 的表达并没有受到破坏。
这些结果表明，胚胎甲基化模式的缺陷不是源于 Dnmt 表达的破坏。
