DNA Damage Responses in Mouse Primordial Germ Cells [RNA-Seq]. DNA Damage Responses in Mouse Primordial Germ Cells [RNA-Seq]

Germ cells specified during fetal development form the foundation of the mammalian germline. These primordial germ cells (PGCs) undergo rapid proliferation, yet the germline is highly refractory to mutation accumulation compared to somatic cells. Importantly, while the presence of endogenous or exogenous DNA damage has the potential to impact PGCs, there is little known about how these cells respond to stressors. To better understand the DNA damage response (DDR) in these cells, we exposed pregnant mice to ionizing radiation (IR) at specific gestational time points and assessed the DDR in PGCs. Our results show that PGCs prior to sex determination lack a G1 cell cycle checkpoint. Additionally, the response to IR-induced DNA damage differs between female and male PGCs post-sex determination. IR of female PGCs caused uncoupling of germ cell differentiation and meiotic initiation, while male PGCs exhibited repression of piRNA metabolism and transposon de-repression. Overall design: 17 samples of purified mouse primordial germ cells were collected for RNA-sequencing. There were two conditions (either with or without ionizing radiation).

胎儿发育过程中特化的生殖细胞，构成了哺乳动物生殖系的基础。这些原始生殖细胞（primordial germ cells, PGCs）会经历快速增殖，但相较于体细胞，生殖系的突变积累进程受到显著抑制。值得注意的是，尽管内源性或外源性DNA损伤均可能对原始生殖细胞造成影响，但目前学界对这类细胞如何响应应激刺激仍知之甚少。为了更深入解析这类细胞的DNA损伤应答（DNA damage response, DDR）机制，我们在特定妊娠时间点对孕鼠施加电离辐射（ionizing radiation, IR），并对原始生殖细胞的DNA损伤应答进行检测分析。研究结果显示，性别分化前的原始生殖细胞并不具备G1细胞周期检验点。此外，性别分化后的雌性与雄性原始生殖细胞，对电离辐射诱导的DNA损伤的响应模式存在显著差异：电离辐射处理雌性原始生殖细胞后，会导致生殖细胞分化与减数分裂起始发生解偶联；而雄性原始生殖细胞则表现出piRNA代谢受抑制以及转座子去抑制的现象。实验整体设计：本研究共收集17份纯化的小鼠原始生殖细胞样本用于RNA测序，实验设置两组处理条件：施加电离辐射组与未施加电离辐射对照组。