Ubiquitin-specific-processing protease 7 (Usp7) is a key deubiquitinase controlling epigenetic modification and regulating the self-renewal, proliferation, and differentiation of stem cells. However, the functions and mechanisms of action of Usp7 on female germline stem cells (FGSCs) are unknown. Here, we demonstrated that Usp7 regulated FGSC self-renewal via DNA methylation. The results of Cell Counting Kit-8 and 5-ethynyl-20-deoxyuridine assays showed that the viability and proliferation of FGSCs were negatively regulated by Usp7. Moreover, Usp7 downregulated the expression of self-renewal genes, such as Oct4, Etv5, Foxo1, and Akt, but upregulated the expression of differentiation-related genes including Stra8 and Sycp3. Mechanistically, RNA-seq results showed that Usp7 negatively regulated FGSC self-renewal but positively modulated differentiation in FGSCs. Meanwhile, both overexpression and knockdown of Usp7 resulted in significant changes in DNA methylation and histone modification in FGSCs. Additionally, RNA-seq and MeDIP-seq analyses showed that Usp7 regulates the self-renewal and differentiation of FGSCs mainly through DNA methylation rather than histone modification, which was also confirmed by a rescue assay. Our study not only offers a novel method to research FGSC self-renewal and differentiation in view of epigenetic modifications, but also provides a deep understanding of FGSC development.

泛素特异性加工蛋白酶 7 ( Usp7 ) 是一种关键的去泛素酶，它控制表观遗传修饰，调节干细胞的自我更新、增殖和分化。然而， Usp7对雌性生殖干细胞（FGSCs）的功能和作用机制尚不清楚。在这里，我们证明了Usp7通过 DNA 甲基化调节 FGSC 自我更新。Cell Counting Kit-8 和 5-ethynyl-20-deoxyuridine 检测结果表明，FGSCs 的活力和增殖受到 Usp7 的负调控。此外，Usp7下调Oct4、Etv5、Foxo1等自我更新基因的表达。Akt ，但上调了包括Stra8和Sycp3在内的分化相关基因的表达。从机制上讲，RNA-seq 结果显示Usp7负调控 FGSC 自我更新，但正调控 FGSC 分化。同时，Usp7 的过表达和敲低均导致FGSCs中 DNA 甲基化和组蛋白修饰的显着变化。此外，RNA-seq 和 MeDIP-seq 分析表明，Usp7主要通过 DNA 甲基化而不是组蛋白修饰来调节 FGSC 的自我更新和分化，这也得到了拯救试验的证实。我们的研究不仅提供了一种从表观遗传修饰角度研究FGSC自我更新和分化的新方法，而且还提供了对FGSC发展的深入理解。