Cell-free mitochondrial DNA (cf-mtDNA) released into the extracellular environment can cause cellular inflammatory responses and damage. Here, we investigated the effects of cf-mtDNA on mouse ovarian granulosa cell function and on the developmental competence of oocytes matured in vitro. Granulosa cells in the cf-mtDNA treatment group had a lower ATP content (P < 0.05), a higher apoptotic cell percentage (P < 0.01), and higher mRNA and protein levels of apoptosis-related factors than the control group (P < 0.01). TLR9, NF-кB p65 and MAPK p38 expression levels in granulosa cells were significantly increased in the cf-mtDNA treatment group (P < 0.05). The blastocyst formation rate of aged mice oocytes matured in vitro decreased significantly (P < 0.05) when cf-mtDNA was added to the media, compared with the control. However, the oocytes from young mice were not affected. Our results suggest that cf-mtDNA may impair granulosa cell function and induce granulosa cell apoptosis, subsequently decreasing blastocyst development in aged oocytes. This role of cf-mtDNA may be associated with the binding to TLR9 and the activation of NF-кB p65 and MAPK p38 signaling pathways.

释放到细胞外环境中的无细胞线粒体 DNA (cf-mtDNA) 可引起细胞炎症反应和损伤。在这里，我们研究了小鼠卵巢颗粒细胞的功能和成熟卵母细胞的发育能力CF-线粒体DNA的影响体外。与对照组相比，cf-mtDNA处理组颗粒细胞ATP含量较低（P  < 0.05），凋亡细胞百分比较高（P  < 0.01），凋亡相关因子的mRNA和蛋白水平较高（P  < 0.01） ）。cf-mtDNA治疗组颗粒细胞中TLR9、NF-кB p65和MAPK p38表达水平显着升高（P  < 0.05）。老年小鼠卵母细胞成熟的囊胚形成率 与对照相比，在培养基中加入 cf-mtDNA 后体外显着降低（P < 0.05）。然而，来自年轻小鼠的卵母细胞没有受到影响。我们的结果表明，cf-mtDNA 可能会损害颗粒细胞功能并诱导颗粒细胞凋亡，从而降低老年卵母细胞的囊胚发育。cf-mtDNA 的这种作用可能与与 TLR9 的结合以及 NF-кB p65 和 MAPK p38 信号通路的激活有关。