Department of Otolaryngology, Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, 310051, People's Republic of China.
Reproductive Medicine Center, Hangzhou Women's Hospital (Hangzhou Maternity and Child Health Care Hospital), Shangcheng District, No. 369 Kunpeng Road, Hangzhou, 310008, People's Republic of China.
J Ovarian Res. 2023 Jul 11;16(1):137. doi: 10.1186/s13048-023-01228-9.
Folliculogenesis is a complex network of interacting cellular signals between somatic cells and oocytes. Many components in ovarian follicular fluid (FF) dynamically change during folliculogenesis and play a positive role in oocyte maturation. Previous studies have reported that lysophosphatidic acid (LPA) promotes cumulus cell expansion, oocyte nuclear maturation, and in vitro maturation of oocytes.
Initially, the expression of LPA was raised in matured FF significantly (P < 0.0001). Then, 10 μM LPA treated for 24 h in human granulosa cells (KGNs) aggravated cell proliferation, with increased autophagy, and reduced apoptosis. Meanwhile, we demonstrated that LPA mediated cell function through the PI3K-AKT-mTOR signaling pathway as PI3K inhibitor (LY294002) significantly prevented LPA-induced AKT, mTOR phosphorylation and autophagy activation. Such results were also verified by immunofluorescence staining and flow cytometry. In addition, an autophagy inhibitor 3 methyladenine (3MA) could also alleviate the effects of LPA, by activating apoptosis through PI3K-AKT-mTOR pathways. Finally, we found blockade with Ki16425 or knockdown LPAR1, alleviated LPA mediated autophagy activation in KGNs, suggesting that LPA enhances autophagy through activation of the LPAR1 and PI3K-AKT-mTOR signaling pathways.
This study demonstrates that increased LPA activated PI3K-Akt-mTOR pathway through LPAR1 in granulosa cells, suppressing apoptosis by enhancing autophagy, which might play a role in oocyte maturation in vivo.
卵泡发生是卵母细胞与体细胞之间相互作用的细胞信号的复杂网络。在卵泡发生过程中，许多卵巢卵泡液（FF）中的成分动态变化，并对卵母细胞成熟发挥积极作用。先前的研究报道，溶血磷脂酸（LPA）促进卵丘细胞扩张、卵母细胞核成熟和卵母细胞体外成熟。
最初，成熟 FF 中 LPA 的表达显著升高（P < 0.0001）。然后，在人颗粒细胞（KGN）中用 10 μM LPA 处理 24 h 会加重细胞增殖，增加自噬，减少凋亡。同时，我们证明 LPA 通过 PI3K-AKT-mTOR 信号通路介导细胞功能，因为 PI3K 抑制剂（LY294002）显著阻止了 LPA 诱导的 AKT、mTOR 磷酸化和自噬激活。这些结果也通过免疫荧光染色和流式细胞术得到了验证。此外，自噬抑制剂 3-甲基腺嘌呤（3MA）也可以通过激活 PI3K-AKT-mTOR 通路来减轻 LPA 的作用，从而通过激活细胞凋亡来减轻 LPA 的作用。最后，我们发现用 Ki16425 阻断或用 LPAR1 敲低，减轻了 LPA 在 KGNs 中介导的自噬激活，表明 LPA 通过激活 LPAR1 和 PI3K-AKT-mTOR 信号通路增强自噬。
本研究表明，在颗粒细胞中，LPA 通过 LPAR1 增加 LPA，激活 PI3K-Akt-mTOR 通路，通过增强自噬抑制凋亡，这可能在体内卵母细胞成熟中发挥作用。
