Induction of fetal meiotic oocytes from embryonic stem cells in cynomolgus monkeys (RNA-Seq II)

Human in vitro oogenesis provides a framework for clarifying the mechanism of human oogenesis. To create its benchmark, it is vital to promote in vitro oogenesis using a model physiologically close to humans. Here, we establish a foundation for in vitro oogenesis in cynomolgus (cy) monkeys (Macaca fascicularis): cy female embryonic stem cells harboring one active and one inactive X chromosome (Xa and Xi, respectively) differentiate robustly into primordial germ cell-like cells, which in xenogeneic reconstituted ovaries develop efficiently into oogonia and, remarkably, further into meiotic oocytes at the zygotene stage. This differentiation entails comprehensive epigenetic reprogramming, including Xi reprogramming, yet Xa and Xi remain epigenetically asymmetric with, as partly observed in vivo, incomplete Xi reactivation. In humans and monkeys, the Xi epigenome in pluripotent stem cells functions as an Xi-reprogramming determinant. We further show that developmental pathway over-activations with suboptimal up-regulation of relevant meiotic genes impede in vitro meiotic progression. Cy in vitro oogenesis exhibits critical homology with the human system, including with respect to bottlenecks, providing a salient model for advancing human in vitro oogenesis. RNA-Seq analysis of Cynomolgus xrOvary and human iPSC

人类体外卵发生（in vitro oogenesis）为阐明人类卵发生的内在机制搭建了研究框架。为构建该领域的基准数据集，采用生理层面贴近人类的模型以推动体外卵发生研究至关重要。本研究中，我们为食蟹猴（cynomolgus monkey, 简称cy, 学名Macaca fascicularis）的体外卵发生奠定了研究基础：携带一条活性X染色体（Xa）与一条失活X染色体（Xi）的食蟹猴雌性胚胎干细胞，可稳定高效分化为原始生殖细胞样细胞（primordial germ cell-like cells）；这类细胞在异种重构卵巢（xenogeneic reconstituted ovaries）中可进一步高效发育为卵原细胞，且显著地可进一步进展至偶线期（zygotene stage）的减数分裂卵母细胞。该分化过程伴随全面的表观重编程（epigenetic reprogramming），其中包括Xi的重编程；但Xa与Xi仍维持表观遗传不对称性，且如体内（in vivo）部分观察到的那样，Xi的重激活并不完全。在人类与猴类中，多能干细胞（pluripotent stem cells）内的Xi表观基因组可作为Xi重编程的决定性调控因素。我们进一步证实，发育通路（developmental pathway）过度激活且伴随减数分裂相关基因上调不足的情况，会阻碍体外减数分裂进程。食蟹猴体外卵发生模型与人类系统存在关键同源性，包括在瓶颈环节层面，这为推动人类体外卵发生研究提供了极具价值的实验模型。本数据集包含食蟹猴xrOvary与人类诱导多能干细胞（induced pluripotent stem cells, 缩写iPSC）的RNA测序（RNA-Seq）分析。