Yu Tong, Qi Xin, Zhang Ling, Ning Wei, Gao Di, Xu Tengteng, Ma Yangyang, Knott Jason G, Sathanawongs Anucha, Cao Zubing, Zhang Yunhai
Anhui Province Key Laboratory of Local Livestock and Poultry, Genetical Resource Conservation and Breeding, College of Animal Science and Technology, Anhui Agricultural University, Hefei 230036, China.
Developmental Epigenetics Laboratory, Department of Animal Science, Michigan State University, East Lansing, MI48824, USA.
Zygote. 2021 Dec;29(6):417-426. doi: 10.1017/S0967199420000799. Epub 2021 Apr 23.
N6-Methyladenosine (m6A) regulates oocyte-to-embryo transition and the reprogramming of somatic cells into induced pluripotent stem cells. However, the role of m6A methylation in porcine early embryonic development and its reprogramming characteristics in somatic cell nuclear transfer (SCNT) embryos are yet to be known. Here, we showed that m6A methylation was essential for normal early embryonic development and its aberrant reprogramming in SCNT embryos. We identified a persistent occurrence of m6A methylation in embryos between 1-cell to blastocyst stages and m6A levels abruptly increased during the morula-to-blastocyst transition. Cycloleucine (methylation inhibitor, 20 mM) treatment efficiently reduced m6A levels, significantly decreased the rates of 4-cell embryos and blastocysts, and disrupted normal lineage allocation. Moreover, cycloleucine treatment also led to higher levels in both apoptosis and autophagy in blastocysts. Furthermore, m6A levels in SCNT embryos at the 4-cell and 8-cell stages were significantly lower than that in parthenogenetic activation (PA) embryos, suggesting an abnormal reprogramming of m6A methylation in SCNT embryos. Correspondingly, expression levels of m6A writers (METTL3 and METTL14) and eraser (FTO) were apparently higher in SCNT 8-cell embryos compared with their PA counterparts. Taken together, these results indicated that aberrant nuclear transfer-mediated reprogramming of m6A methylation was involved in regulating porcine early embryonic development.
N6-甲基腺苷（m6A）调控卵母细胞向胚胎的转变以及体细胞重编程为诱导多能干细胞的过程。然而，m6A甲基化在猪早期胚胎发育中的作用及其在体细胞核移植（SCNT）胚胎中的重编程特征尚不清楚。在此，我们表明m6A甲基化对于正常的早期胚胎发育及其在SCNT胚胎中的异常重编程至关重要。我们发现，在1细胞至囊胚阶段的胚胎中持续存在m6A甲基化，并且在桑椹胚向囊胚转变过程中m6A水平急剧增加。环亮氨酸（甲基化抑制剂，20 mM）处理有效降低了m6A水平，显著降低了4细胞胚胎和囊胚的比率，并扰乱了正常的谱系分配。此外，环亮氨酸处理还导致囊胚中的凋亡和自噬水平升高。此外，SCNT胚胎在4细胞和8细胞阶段的m6A水平显著低于孤雌激活（PA）胚胎，这表明SCNT胚胎中m6A甲基化存在异常重编程。相应地，与PA胚胎相比，SCNT 8细胞胚胎中m6A写入器（METTL3和METTL14）和擦除器（FTO）的表达水平明显更高。综上所述，这些结果表明，m6A甲基化的异常核移植介导的重编程参与调控猪早期胚胎发育。
