The shift from maternal to embryonic control is a critical developmental milestone in preimplantation development. Widespread transcriptomic and epigenetic remodeling facilitate this transition from terminally differentiated gametes to totipotent blastomeres, but the identity of transcription factors (TF) and genomic elements regulating embryonic genome activation (EGA) are poorly defined. The timing of EGA is species-specific, e.g., the timing of murine and human EGA differ significantly. To deepen our understanding of mammalian EGA, here we profile changes in open chromatin during bovine preimplantation development. Before EGA, open chromatin is enriched for maternal TF binding, similar to that observed in humans and mice. During EGA, homeobox factor binding becomes more prevalent and requires embryonic transcription. A cross-species comparison of open chromatin during preimplantation development reveals strong similarity in the regulatory circuitry underlying bovine and human EGA compared to mouse. Moreover, TFs associated with murine EGA are not enriched in cattle or humans, indicating that cattle may be a more informative model for human preimplantation development than mice.

从母体控制到胚胎控制的转变是着床前发育的一个关键发育里程碑。广泛的转录组和表观遗传重塑促进了从终末分化配子到全能卵裂球的转变，但转录因子 (TF) 和调节胚胎基因组激活 (EGA) 的基因组元件的身份定义不清。EGA 的时间是物种特异性的，例如，鼠和人类 EGA 的时间显着不同。为了加深我们对哺乳动物 EGA 的理解，我们在此分析了牛着床前发育过程中开放染色质的变化。在 EGA 之前，开放染色质富含母体 TF 结合，类似于在人类和小鼠中观察到的情况。在 EGA 期间，同源盒因子结合变得更加普遍并且需要胚胎转录。植入前发育过程中开放染色质的跨物种比较显示，与小鼠相比，牛和人 EGA 的调节电路具有很强的相似性。此外，与鼠 EGA 相关的 TF 在牛或人类中并未富集，这表明牛可能是比小鼠更能提供人类植入前发育的信息模型。