Zhou Xin-Yu, Liu Liang-Liang, Jia Wen-Chao, Pan Chuan-Ying
College of Life Sciences, Northwest A&F University, Yangling 712100, P.R. China.
School of Computer Science & Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003, P.R. China.
J Integr Agric. 2016 Mar;15(3):618-628. doi: 10.1016/S2095-3119(15)61100-5. Epub 2016 Apr 22.
Previous studies have shown that octamer-binding transcription factor 4 (Oct4) plays a significant role in early embryonic development of mammalian animals, and different expression levels induce multi-lineage differentiation which are regulated by DNA methylation. To explore the relationship between the methylation pattern of gene exon 1 and embryonic development, in this work, five different tissues (heart, liver, lung, cerebrum and cerebellum) from three germ layers were chosen from low age (50-60 d) and advanced age (60-70 d) of fetal cattle and the differences between tissues or ages were analyzed, respectively. The result showed that the DNA methylation level of gene exon 1 was significant different (<0.01) between any two of three germ layers in low age (<60 d), but kept steady of advanced age (>0.05) (>60 d), suggesting that 60-d post coital was an important boundary for embryonic development. In addition, in ectoderm (cerebrum and cerebellum), there was no significant methylation difference of gene exon 1 between low age and advanced age (>0.05), but the result of endoderm (liver and lung) and mesoderm (heart) were on the contrary (<0.01), which indicated the development of ectoderm was earlier than endoderm and mesoderm. The methylation differences from the 3rd, 5th and 9th CpG-dinucleotide loci of gene exon 1 were significantly different between each two of three germ layers (<0.05), indicating that these three loci may have important influence on bovine embryonic development. This study showed that bovine germ layers differentiation was significantly related to the DNA methylation status of gene exon 1. This work firstly identified the DNA methylation profile of bovine gene exon 1 and its association with germ layers development in fetus and adult of cattle. Moreover, the work also provided epigenetic information for further studying bovine embryonic development and cellular reprogramming.
先前的研究表明，八聚体结合转录因子4（Oct4）在哺乳动物的早期胚胎发育中起着重要作用，不同的表达水平会诱导多谱系分化，而这一过程受DNA甲基化调控。为了探究基因外显子1的甲基化模式与胚胎发育之间的关系，在本研究中，从低龄（50 - 60天）和高龄（60 - 70天）胎牛的三个胚层中选取了五种不同组织（心脏、肝脏、肺、大脑和小脑），并分别分析了组织间和年龄间的差异。结果表明，低龄（<60天）时，三个胚层中任意两个胚层之间基因外显子1的DNA甲基化水平差异显著（<0.01），但高龄（>60天）时保持稳定（>0.05），这表明交配后60天是胚胎发育的一个重要界限。此外，在外胚层（大脑和小脑）中，低龄和高龄之间基因外显子1的甲基化无显著差异（>0.05），但内胚层（肝脏和肺）和中胚层（心脏）的结果则相反（<0.01），这表明外胚层的发育早于内胚层和中胚层。基因外显子1的第3、5和9个CpG二核苷酸位点在三个胚层两两之间的甲基化差异显著（<0.05），表明这三个位点可能对牛胚胎发育有重要影响。本研究表明，牛胚层分化与基因外显子1的DNA甲基化状态显著相关。这项工作首次确定了牛基因外显子1的DNA甲基化图谱及其与牛胎儿和成年牛胚层发育的关联。此外，该研究还为进一步研究牛胚胎发育和细胞重编程提供了表观遗传信息。
