Dynamic regulation of DNA methyltransferases in human oocytes and preimplantation embryos after assisted reproductive technologies
Dynamic regulation of DNA methyltransferases in human oocytes and preimplantation embryos after assisted reproductive technologies
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DOI：
10.1093/molehr/gau049
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发表时间：
2014-09-01
影响因子：
4
通讯作者：
De Rycke, Martine
中科院分区：
文献类型：
--
作者：
Petrussa, Laetitia;Van de Velde, Hilde;De Rycke, Martine
DNA甲基化是一种关键的表观遗传修饰，对于正常胚胎发育至关重要。主要的表观遗传重编程发生在配子发生期间和早期胚胎中。复杂的 DNA 甲基化模式由 DNA 甲基转移酶 (DNMT) 建立和维持。然而，辅助生殖技术 (ART) 对 DNA 甲基化重编程酶的影响主要在小鼠中进行研究，而在人类卵母细胞和胚胎中研究较少。通过免疫细胞化学分析了四种已知 DNMT 在人类卵母细胞和 IVF/ICSI 胚胎中的表达和定位模式，并在优质新鲜胚胎参考组和异常发育胚胎组或冷冻保存后的胚胎组之间进行比较。在人类中，DNMT1（而不是 DNMT1）似乎是维持早期胚胎甲基化的关键角色。 DNMT3b（而不是 DNMT3a 和 DNMT3L）似乎可以确保植入前囊胚中的整体 DNA 重甲基化。 DNMT3L 是小鼠母体印记甲基化的重要调节因子，但在人卵母细胞（GV、MI 和 MII 阶段）中未检测到。我们的研究证实了哺乳动物 DNA 甲基化酶存在物种差异。在质量差的新鲜胚胎中，向核 DNMT3b 表达的转变被延迟，并且核 DNMT1、DNMT1s 和 DNMT3b 表达不太常见。与参考胚胎相比，冷冻胚胎中显示核 DNMT1 的数量较少，同时还观察到向核 DNMT3b 的延迟转换和延长的 DNMT1s 时间表达模式。在异常发育的胚胎和冷冻保存的胚胎中，DNMT 的空间和时间表达模式似乎受到干扰。必须进行进一步的研究，以了解冷冻保存后胚胎 DNMT 表达可能受到干扰是否会产生任何长期发育后果。
DNAmethylation is a key epigenetic modification which is essential for normal embryonic development. Major epigenetic reprogramming takes place during gametogenesis and in the early embryo; the complex DNA methylation patterns are established and maintained by DNA methyltransferases (DNMTs). However, the influence of assisted reproductive technologies (ART) on DNA methylation reprogramming enzymes has predominantly been studied in mice and less so in human oocytes and embryos. The expression and localization patterns of the four known DNMTs were analysed in human oocytes and IVF/ICSI embryos by immunocytochemistry and compared between a reference group of good quality fresh embryos and groups of abnormally developing embryos or embryo groups after cryopreservation. In humans, DNMT1 orather than DNMT1s seems to be the key player for maintaining methylation in early embryos. DNMT3b, rather than DNMT3a and DNMT3L, appears to ensure global DNA remethylation in the blastocysts before implantation. DNMT3L, an important regulator of maternal imprint methylation in mouse, was not detected in human oocytes (GV, MI and MII stage). Our study confirms the existence of species differences for mammalian DNA methylation enzymes. In poor quality fresh embryos, the switch towards nuclear DNMT3b expression was delayed and nuclear DNMT1, DNMT1s and DNMT3b expression was less common. Compared with the reference embryos, a smaller number of cryopreserved embryos showed nuclear DNMT1, while a delayed switch to nuclear DNMT3b and an extended DNMT1s temporal expression pattern were also observed. The spatial and temporal expression patterns of DNMTs seem to be disturbed in abnormally developing embryos and in embryos that have been cryopreserved. Further research must be performed in order to understand whether the potentially disturbed embryonic DNMT expression after cryopreservation has any long-term developmental consequences.