FIGLA, LHX8 and SOHLH1 transcription factor networks regulate mouse oocyte growth and differentiation. FIGLA, LHX8 and SOHLH1 transcription factor networks regulate mouse oocyte growth and differentiation

Germ-cell transcription factors control gene networks that regulate primordial follicle formation and oocyte differentiation during early, postnatal mouse oogenesis. Taking advantage of gene-edited mice lacking transcription factors expressed in female germ cells, we analyzed global gene expression profiles in perinatal ovaries from wildtype, FiglaNull, Lhx8Null and SohlhNull mice. Figla deficiency dysregulates expression of meiosis-related genes (e.g., Sycp3, Rad51 and Msy2) and a variety of genes (e.g., Nobox, Lhx8, Taf4b, Sohlh1, Sohlh2 and Gdf9) associated with oocyte growth and differentiation. The absence of FIGLA significantly impedes meiotic progression, causes DNA damage and results in oocyte apoptosis. Moreover, we find that FIGLA and other transcriptional regulators (e.g., NOBOX, LHX8, SOHLH1 and SOHLH2) are co-expressed in the same subset of germ cells in perinatal ovaries and Figla ablation dramatically disrupts KIT, NOBOX, LHX8, SOHLH1 and SOHLH2 expression. In addition, not only do FIGLA, SOHLH1 and LHX8 cross-regulate each other, they also cooperate by direct interaction with each during early oocyte development and share downstream gene targets. Thus, our findings substantiate a major role for FIGLA, LHX8 and SOHLH1 as multifunctional regulators of networks necessary for oocyte maintenance and differentiation during early folliculogenesis. Overall design: RNA-seq was performed using embryonic day 18.5 (E18.5) or postnatal day 0 (P0) ovaires between control and Figla knockout mice in order to identify the differentially expressed genes. RNA-seq was performed using P0 ovaires between control and Lhx8 knockout mice in order to identify the differentially expressed genes.

生殖细胞转录因子可调控小鼠出生后早期卵子发生过程中，介导原始卵泡形成与卵母细胞分化的基因网络。本研究利用雌性生殖细胞中缺失特定转录因子的基因编辑小鼠，对野生型、Figla缺失型（FiglaNull）、Lhx8缺失型（Lhx8Null）及Sohlh缺失型（SohlhNull）小鼠的围产期卵巢开展全局基因表达谱分析。

Figla缺陷会异常调控减数分裂相关基因（如Sycp3、Rad51及Msy2）的表达，同时也会扰乱多种与卵母细胞生长及分化相关的基因（如Nobox、Lhx8、Taf4b、Sohlh1、Sohlh2及Gdf9）的转录。FIGLA的缺失会显著阻滞减数分裂进程，引发DNA损伤，并最终导致卵母细胞凋亡。此外，本研究发现FIGLA与其他转录调控因子（如NOBOX、LHX8、SOHLH1及SOHLH2）可在围产期卵巢的同一生殖细胞亚群中共表达，且Figla敲除会大幅干扰KIT、NOBOX、LHX8、SOHLH1及SOHLH2的基因表达。

进一步研究显示，FIGLA、SOHLH1与LHX8不仅可彼此交叉调控，还能在早期卵母细胞发育过程中通过直接相互作用实现协同调控，并共享下游靶基因。综上，本研究证实FIGLA、LHX8及SOHLH1作为多功能调控因子，在早期卵泡发生过程中，对维持卵母细胞存活与分化所必需的基因网络发挥核心调控作用。

实验设计概述：本研究分别以对照组与Figla敲除小鼠的胚胎第18.5天（E18.5）或出生后第0天（P0）卵巢为样本开展RNA测序，以筛选差异表达基因；同时以对照组与Lhx8敲除小鼠的P0卵巢为样本开展RNA测序，用于鉴定差异表达基因。