Small noncoding RNAs (sRNAs) play important roles during the oocyte-to-embryo transition (OET), when the maternal phenotype is reprogrammed and the embryo genome is gradually activated. The transcriptional program driving early human development has been studied with the focus mainly on protein-coding RNAs, and expression dynamics of sRNAs remain largely unexplored. We profiled sRNAs in human oocytes and early embryos using an RNA-sequencing (RNA-seq) method suitable for low inputs of material. We show that OET in humans is temporally coupled with the transition from predominant expression of oocyte short piRNAs (os-piRNAs) in oocytes, to activation of microRNA (miRNA) expression in cleavage stage embryos. Additionally, 3′ mono- and oligoadenylation of miRNAs is markedly increased in zygotes. We hypothesize that this may modulate the function or stability of maternal miRNAs, some of which are retained throughout the first cell divisions in embryos. This study is the first of its kind elucidating the dynamics of sRNA expression and miRNA modification along a continuous trajectory of early human development and provides a valuable data set for in-depth interpretative analyses.

中文翻译：

---

人卵母细胞和早期胚胎中的小 RNA 表达和 miRNA 修饰动力学

小非编码 RNA (sRNA) 在卵母细胞-胚胎转变 (OET) 过程中发挥重要作用，此时母体表型被重新编程，胚胎基因组逐渐被激活。已经研究了驱动早期人类发育的转录程序，主要集中在蛋白质编码 RNA 上，而 sRNA 的表达动力学在很大程度上仍未探索。我们使用适合低输入材料的 RNA 测序 (RNA-seq) 方法分析人类卵母细胞和早期胚胎中的 sRNA。我们表明，人类的 OET 在时间上与卵母细胞中卵母细胞短 piRNAs (os-piRNAs) 的主要表达转变为卵裂期胚胎中 microRNA (miRNA) 表达的激活有关。此外，受精卵中 miRNA 的 3' 单腺苷酸和寡腺苷酸化显着增加。我们假设这可能会调节母体 miRNA 的功能或稳定性，其中一些在胚胎的第一次细胞分裂中保留。本研究首次阐明了人类早期发育过程中 sRNA 表达和 miRNA 修饰的动态变化，并为深入的解释性分析提供了有价值的数据集。