State Key Laboratory of Animal Biotech Breeding, College of Animal Science and Technology, China Agricultural University, Beijing, China.
School of Municipal and Environmental Engineering, Shandong Jianzhu University, Jinan, China.
Biol Reprod. 2023 Jun 9;108(6):871-886. doi: 10.1093/biolre/ioad038.
The regulation of mammalian early-embryonic development is a complex, coordinated process that involves widespread transcriptomic and epigenetic remodeling. The main cause of developmental failure in preimplantation embryos after in vitro fertilization is the irreversible arrested-at-cleavage stage. To deepen our understanding of this embryonic block, we profiled a single-cell multi-omics map of copy number variations (CNVs), the transcriptome, the DNA methylome, and the chromatin state of bovine eight-cell embryos with a two-cell fate that either arrested or developed into blastocysts. To do this, we sequenced a biopsied blastomere and tracked the developmental potential of the remaining cells. Aneuploid embryos inferred by CNVs from DNA- and RNA-library data tended to lose their developmental potency. Analysis of distinct genomic regions of DNA methylation and chromatin accessibility revealed that enrichment of gene function and signaling pathways, such as the MAPK signaling pathway, was altered in arrested euploid eight-cell embryos compared with blastocyst-developed euploid eight-cell embryos. Moreover, the RNA expression and chromatin accessibility of embryonic genome activation-associated genes were lower in arrested euploid embryos than in blastocyst-developed embryos. Taken together, our results indicate that the developmental block of eight-cell embryos can be caused by multiple molecular layers, including CNVs, abnormality of DNA methylation and chromatin accessibility, and insufficient expression of embryonic genome activation-associated genes. Our integrated and comprehensive data set provides a valuable resource to further dissect the exact mechanisms underlying the arrest of bovine eight-cell embryos in vitro.
哺乳动物早期胚胎发育的调控是一个复杂的、协调的过程，涉及广泛的转录组和表观遗传重塑。体外受精后胚胎着床前发育失败的主要原因是卵裂期不可逆停滞。为了深入了解这种胚胎阻滞，我们对具有二细胞命运的牛 8 细胞胚胎的拷贝数变异 (CNVs)、转录组、DNA 甲基化组和染色质状态进行了单细胞多组学图谱分析，这些胚胎要么停滞，要么发育成囊胚。为此，我们对活检的卵裂球进行了测序，并跟踪了剩余细胞的发育潜力。从 DNA 和 RNA 文库数据推断的非整倍体胚胎往往失去了发育潜能。对 DNA 甲基化和染色质可及性的不同基因组区域的分析表明，与囊胚发育的整倍体 8 细胞胚胎相比，停滞的整倍体 8 细胞胚胎中基因功能和信号通路（如 MAPK 信号通路）的富集发生了改变。此外，停滞的整倍体胚胎中胚胎基因组激活相关基因的 RNA 表达和染色质可及性低于囊胚发育的胚胎。综上所述，我们的结果表明，8 细胞胚胎的发育阻滞可能是由多个分子层面引起的，包括 CNVs、DNA 甲基化和染色质可及性异常以及胚胎基因组激活相关基因表达不足。我们的综合全面数据集为进一步剖析牛 8 细胞胚胎体外阻滞的确切机制提供了有价值的资源。
