Histone demethylase KDM4A overexpression improved the efficiency of corrected human tripronuclear zygote development.

Human zygotes are difficult to obtain for research because of limited resources and ethical debates. Corrected human tripronuclear (ch3PN) zygotes obtained by removal of the extra pronucleus from abnormally fertilized tripronuclear (3PN) zygotes are considered an alternative resource for basic scientific research. In the present study, eight-cell and blastocyst formation efficiency were significantly lower in both 3PN and ch3PN embryos than in normal fertilized (2PN) embryos, while histone H3 lysine 9 trimethylation (H3K9me3) levels were much higher. It was speculated that the aberrant H3K9me3 level detected in ch3PN embryos may be related to low developmental competence. Microinjection of 1000 ng/µl lysine-specific demethylase 4A (KDM4A) mRNA effectively reduced the H3K9me3 level and significantly increased the developmental competence of ch3PN embryos. The quality of ch3PN zygotes improved as the grading criteria, cell number and pluripotent expression significantly increased in response to KDM4A mRNA injection. Developmental genes related to zygotic genome activation (ZGA) were also upregulated. These results indicate that KDM4A activates the transcription of the ZGA program by enhancing the expression of related genes, promoting epigenetic modifications and regulating the developmental potential of ch3PN embryos. The present study will facilitate future studies of ch3PN embryos and could provide additional options for infertile couples.

由于资源有限和伦理争议，人类受精卵难以用于研究。从异常受精的三原核（3PN）受精卵中去除多余原核而获得的矫正人类三原核（ch3PN）受精卵被视为基础科学研究的一种替代资源。在本研究中，3PN和ch3PN胚胎的八细胞和囊胚形成效率均显著低于正常受精（2PN）胚胎，而组蛋白H3赖氨酸9三甲基化（H3K9me3）水平则高得多。据推测，在ch3PN胚胎中检测到的异常H3K9me3水平可能与发育能力低下有关。注射1000 ng/µl赖氨酸特异性去甲基化酶4A（KDM4A）mRNA可有效降低H3K9me3水平，并显著提高ch3PN胚胎的发育能力。随着分级标准、细胞数量和多能性表达因KDM4A mRNA注射而显著增加，ch3PN受精卵的质量得到改善。与受精卵基因组激活（ZGA）相关的发育基因也被上调。这些结果表明，KDM4A通过增强相关基因的表达、促进表观遗传修饰以及调节ch3PN胚胎的发育潜能来激活ZGA程序的转录。本研究将促进未来对ch3PN胚胎的研究，并可为不孕夫妇提供更多选择。