Zhang Lu-Yao, Zhang Ke, Zhao Xi, Tao Hai-Ping, Jia Gong-Xue, Fang You-Gui, Hou Yun-Peng, Yang Qi-En
Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Qinghai, China.
Department of Animal Science, College of Animal Science, Xinjiang Agricultural University, Urumqi, China.
Biol Reprod. 2024 Dec 12;111(6):1220-1234. doi: 10.1093/biolre/ioae141.
Environmental hypoxia adversely impacts the reproduction of humans and animals. Previously, we showed that fetal hypoxia exposure led to granulosa cell (GC) autophagic cell death via the Foxo1/Pi3k/Akt pathway. However, the upstream regulatory mechanisms underlying GC dysfunction remain largely unexplored. Here, we tested the hypothesis that fetal hypoxia exposure altered gene expression programs in adult GCs and impaired ovarian function. We established a fetal hypoxia model in which pregnant mice were maintained in a high-plateau hypoxic environment from gestation day (E) 0-16.5 to study the impact of hypoxia exposure on the ovarian development and subsequent fertility of offspring. Compared with the unexposed control, fetal hypoxia impaired fertility by disordering ovarian function. Specifically, fetal hypoxia caused mitochondrial dysfunction, oxidant stress, and autophagy in GCs in the adult ovary. RNA sequencing analysis revealed that 437 genes were differentially expressed in the adult GCs of exposed animals. Western blotting results also revealed that fetal exposure induced high levels of hypoxia-inducible factor 1-alpha (Hif1a) expression in adult GCs. We then treated granulosa cells isolated from exposed mice with PX-478, a specific pharmacological inhibitor of Hif1a, and found that autophagy and apoptosis were effectively alleviated. Finally, by using a human ovarian granulosa-like tumor cell line (KGN) to simulate hypoxia in vitro, we showed that Hif1a regulated autophagic cell death in GCs through the Pi3k/Akt pathway. Together, these findings suggest that fetal hypoxia exposure induced persistent Hif1a expression, which impaired mitochondrial function and led to autophagic cell death in the GCs of the adult ovary.
环境缺氧对人类和动物的生殖产生不利影响。此前，我们发现胎儿期暴露于缺氧环境会通过Foxo1/Pi3k/Akt信号通路导致颗粒细胞（GC）发生自噬性细胞死亡。然而，GC功能障碍背后的上游调控机制在很大程度上仍未被探索。在此，我们检验了一个假设，即胎儿期暴露于缺氧环境会改变成年GC中的基因表达程序并损害卵巢功能。我们建立了一个胎儿缺氧模型，在该模型中，怀孕小鼠从妊娠第0天（E）至16.5天被置于高原缺氧环境中，以研究缺氧暴露对后代卵巢发育和后续生育能力的影响。与未暴露的对照组相比，胎儿缺氧通过扰乱卵巢功能损害了生育能力。具体而言，胎儿缺氧导致成年卵巢中的GC出现线粒体功能障碍、氧化应激和自噬。RNA测序分析显示，在暴露动物的成年GC中有437个基因差异表达。蛋白质免疫印迹结果还显示，胎儿期暴露会诱导成年GC中缺氧诱导因子1α（Hif1a）的高表达。然后，我们用Hif1a的特异性药理抑制剂PX-478处理从暴露小鼠分离的颗粒细胞，发现自噬和凋亡得到有效缓解。最后，通过使用人卵巢颗粒样肿瘤细胞系（KGN）在体外模拟缺氧，我们表明Hif1a通过Pi3k/Akt信号通路调节GC中的自噬性细胞死亡。总之，这些发现表明，胎儿期暴露于缺氧环境会诱导Hif1a持续表达，这会损害线粒体功能并导致成年卵巢GC发生自噬性细胞死亡。
