Center for Reproductive Medicine, Cheeloo College of Medicine, Shandong University, Jinan, 250012, China.
Key Laboratory of Reproductive Endocrinology of Ministry of Education, Shandong University, Jinan, 250012, China.
Proc Natl Acad Sci U S A. 2022 Aug 23;119(34):e2203208119. doi: 10.1073/pnas.2203208119. Epub 2022 Aug 15.
Preserving a high degree of genome integrity and stability in germ cells is of utmost importance for reproduction and species propagation. However, the regulatory mechanisms of maintaining genome stability in the developing primordial germ cells (PGCs), in which rapid proliferation is coupled with global hypertranscription, remain largely unknown. Here, we find that mouse PGCs encounter a constitutively high frequency of transcription-replication conflicts (TRCs), which lead to R-loop accumulation and impose endogenous replication stress on PGCs. We further demonstrate that the Fanconi anemia (FA) pathway is activated by TRCs and has a central role in the coordination between replication and transcription in the rapidly proliferating PGCs, as disabling the FA pathway leads to TRC and R-loop accumulation, replication fork destabilization, increased DNA damage, dramatic loss of mitotically dividing mouse PGCs, and consequent sterility of both sexes. Overall, our findings uncover the unique source and resolving mechanism of endogenous replication stress during PGC proliferation, provide a biological explanation for reproductive defects in individuals with FA, and improve our understanding of the monitoring strategies for genome stability during germ cell development.
在生殖细胞中保持高度的基因组完整性和稳定性对于繁殖和物种传播至关重要。然而，在快速增殖的原始生殖细胞（PGCs）中维持基因组稳定性的调控机制在很大程度上仍然未知。在这里，我们发现小鼠 PGC 中存在持续存在的转录-复制冲突（TRC），这会导致 R 环积累，并对 PGC 施加内源性复制压力。我们进一步证明，FA 途径被 TRC 激活，并在快速增殖的 PGC 中协调复制和转录方面发挥核心作用，因为 FA 途径的失活会导致 TRC 和 R 环积累、复制叉不稳定、DNA 损伤增加、有丝分裂分裂的小鼠 PGC 大量丢失，以及雌雄两性的不育。总的来说，我们的发现揭示了 PGC 增殖过程中内源性复制应激的独特来源和解决机制，为 FA 个体的生殖缺陷提供了生物学解释，并提高了我们对生殖细胞发育过程中基因组稳定性监测策略的理解。
