Department of Genetic Medicine and Development, University of Geneva, Geneva, Switzerland.
iGE3, Institute of Genetics and Genomics of Geneva, University of Geneva, Geneva, Switzerland.
FASEB J. 2021 Apr;35(4):e21452. doi: 10.1096/fj.202002420R.
Despite the importance of germ cell (GC) differentiation for sexual reproduction, the gene networks underlying their fate remain unclear. Here, we comprehensively characterize the gene expression dynamics during sex determination based on single-cell RNA sequencing of 14 914 XX and XY mouse GCs between embryonic days (E) 9.0 and 16.5. We found that XX and XY GCs diverge transcriptionally as early as E11.5 with upregulation of genes downstream of the bone morphogenic protein (BMP) and nodal/Activin pathways in XY and XX GCs, respectively. We also identified a sex-specific upregulation of genes associated with negative regulation of mRNA processing and an increase in intron retention consistent with a reduction in mRNA splicing in XY testicular GCs by E13.5. Using computational gene regulation network inference analysis, we identified sex-specific, sequential waves of putative key regulator genes during GC differentiation and revealed that the meiotic genes are regulated by positive and negative master modules acting in an antagonistic fashion. Finally, we found that rare adrenal GCs enter meiosis similarly to ovarian GCs but display altered expression of master genes controlling the female and male genetic programs, indicating that the somatic environment is important for GC function. Our data are available on a web platform and provide a molecular roadmap of GC sex determination at single-cell resolution, which will serve as a valuable resource for future studies of gonad development, function, and disease.
尽管生殖细胞 (GC) 分化对于有性生殖至关重要，但支持它们命运的基因网络仍不清楚。在这里，我们通过对 9.0 至 16.5 天胚胎期的 14914 个 XX 和 XY 小鼠 GC 的单细胞 RNA 测序，全面描述了性别决定过程中的基因表达动态。我们发现，XX 和 XY GC 在 E11.5 时就开始在转录水平上出现差异，XX GC 中骨形态发生蛋白 (BMP) 和 nodal/激活素途径下游的基因上调，而 XY GC 中则上调了相应的基因。我们还发现，XX 和 XY 睾丸 GC 中与 mRNA 加工负调控相关的基因以及内含子保留的增加在 E13.5 时表现出性别特异性上调，这与 XY GC 中 mRNA 剪接减少一致。通过计算基因调控网络推断分析，我们在 GC 分化过程中识别出了性别特异性的、顺序的潜在关键调控基因波，揭示了减数分裂基因受正向和负向主模块的调节，这些模块以拮抗的方式发挥作用。最后，我们发现罕见的肾上腺 GC 与卵巢 GC 相似地进入减数分裂，但控制雌性和雄性遗传程序的主基因表达发生改变，这表明体环境对于 GC 功能很重要。我们的数据可在一个网络平台上获取，为单细胞分辨率的 GC 性别决定提供了分子路线图，这将成为未来性腺发育、功能和疾病研究的宝贵资源。
