Animal Biotechnology Laboratory, ICAR-National Institute of Animal Nutrition and Physiology, Bangalore, 560030, India.
Reprod Domest Anim. 2023 Jun;58(6):717-725. doi: 10.1111/rda.14341. Epub 2023 Mar 22.
DNA methylation, considered the most prominent epigenetic mark was important for the gene regulation in embryonic development. The present study aimed at evaluating the effects of metabolic stressors [Non-esterified fatty acid (NEFA), β-hydroxy-butyric acid (BHB), ammonia and urea] exposure during the in vitro ovine oocyte maturation, global DNA methylation, DNA methyltransferase and stress-related gene expression. Colorimetric analysis of global DNA methylation and the expression of the DNA methyltransferase genes (DNMT1, DNMT3A, and DNMT3B) were assessed in the matured oocytes, 2-cell embryos and blastocysts produced in vitro from oocytes exposed with the metabolic stressors during 24 h of the in vitro maturation (IVM). Further, the mRNA expression of the stress-related genes (SOD1, SOD2) in the matured oocytes, 2-cell embryos and blastocysts produced was assessed. Significant difference in global DNA methylation levels between all the treatments tested was observed when compared with control in oocytes, two-cell embryos and blastocysts. Elevated concentration of metabolic stressors resulted in increased expressions of several stress-related genes, i.e., SOD1, SOD2 and in mRNA expression of DNA methyltransferase genes. The present study is the first to report that the DNA methylation was sensitive to the effects of the metabolic stressors in ovine oocytes/embryos. The aberrant expressions of genes during oocyte development targeted in the present study can provide evidence for the early embryo developmental arrest and blastocysts quality. These results highlighted the sensitivity of the early embryogenesis and more precisely of the reprogramming period to metabolites challenges, in a realistic situation of elevated concentration of metabolic stressors.
DNA 甲基化被认为是最重要的表观遗传标记，对于胚胎发育中的基因调控非常重要。本研究旨在评估代谢应激物[非酯化脂肪酸 (NEFA)、β-羟丁酸 (BHB)、氨和尿素]在绵羊卵母细胞体外成熟过程中的暴露对整体 DNA 甲基化、DNA 甲基转移酶和应激相关基因表达的影响。采用比色法分析了暴露于代谢应激物 24 小时的卵母细胞、2 细胞胚胎和体外产生的囊胚中的整体 DNA 甲基化和 DNA 甲基转移酶基因 (DNMT1、DNMT3A 和 DNMT3B)的表达。此外，还评估了成熟卵母细胞、2 细胞胚胎和囊胚中应激相关基因 (SOD1、SOD2)的 mRNA 表达。与对照组相比，所有处理组的卵母细胞、2 细胞胚胎和囊胚中的整体 DNA 甲基化水平均存在显著差异。代谢应激物浓度升高导致几个应激相关基因（即 SOD1、SOD2）的表达增加，以及 DNA 甲基转移酶基因的 mRNA 表达增加。本研究首次报道代谢应激物对绵羊卵母细胞/胚胎的 DNA 甲基化有影响。本研究中靶向的卵母细胞发育过程中基因的异常表达可为早期胚胎发育停滞和囊胚质量提供证据。这些结果强调了早期胚胎发生的敏感性，更准确地说，是在代谢应激物浓度升高的现实情况下，对重新编程期的敏感性。
