Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, Northwest A&F University, Yangling 712100, China.
Int J Mol Sci. 2022 Aug 3;23(15):8629. doi: 10.3390/ijms23158629.
Oocyte vitrification has been widely used in the treatment of infertility and fertility preservation. However, vitrification-induced mitochondrial damage adversely affects oocyte development. Several studies have reported that mitochondrial calcium uptake protein 1 (MICU1) regulates the uptake of mitochondrial calcium by the mitochondrial calcium uniporter (MCU) and subsequently controls aerobic metabolism and oxidative stress in mitochondria, but research considering oocytes remains unreported. We evaluated whether the addition of MICU1 modulators enhances mitochondrial activity, pyruvate metabolism, and developmental competence after warming of MII oocytes.
Retrieved MII oocytes of mice were classified as vitrified or control groups. After thawing, oocytes of vitrified group were cultured with or without DS16570511 (MICU1 inhibitor) and MCU-i4 (MICU1 activator) for 2 h.
Mitochondrial Ca concentration, pyruvate dephosphorylation level, and MICU1 expression of MII oocytes were significantly increased after vitrification. These phenomena were further exacerbated by the addition of MCU-i4 and reversed by the addition of DS16570511 after warming. However, the mitochondrial membrane potential (MMP) and adenosine triphosphate (ATP) in vitrified-warmed MII oocytes drop significantly after vitrification, which was improved after MCU-i4 treatment and decreased significantly after DS16570511 treatment. The vitrification process was able to elicit a development competence reduction. After parthenogenetic activation, incubation of the thawed oocytes with MCU-i4 did not alter the cleavage and blastocyst rates. Moreover, incubation of the thawed oocytes with DS16570511 reduced the cleavage and blastocyst rates.
MICU1-mediated increasing mitochondrial calcium uptake after vitrification of the MII oocytes promoted the pyruvate oxidation, and this process may maintain oocyte development competence by compensating for the consumption of ATP under stress state.
卵母细胞玻璃化已广泛应用于不孕不育治疗和生育力保存。然而，玻璃化诱导的线粒体损伤会对卵母细胞的发育产生不利影响。有几项研究报道，线粒体钙摄取蛋白 1（MICU1）通过调节线粒体钙单向转运体（MCU）摄取线粒体钙，从而控制线粒体中的有氧代谢和氧化应激，但关于卵母细胞的研究尚未报道。我们评估了添加 MICU1 调节剂是否能增强 MII 期卵母细胞解冻后的线粒体活性、丙酮酸代谢和发育能力。
将从老鼠体内取出的 MII 期卵母细胞分为玻璃化组和对照组。解冻后，玻璃化组的卵母细胞用或不用 DS16570511（MICU1 抑制剂）和 MCU-i4（MICU1 激活剂）培养 2 小时。
玻璃化后，MII 期卵母细胞的线粒体 Ca 浓度、丙酮酸去磷酸化水平和 MICU1 表达均显著增加。这些现象在添加 MCU-i4 后进一步加剧，在解冻后添加 DS16570511 后逆转。然而，玻璃化后解冻的 MII 期卵母细胞的线粒体膜电位（MMP）和三磷酸腺苷（ATP）明显下降，添加 MCU-i4 后有所改善，添加 DS16570511 后明显下降。玻璃化过程会导致发育能力下降。经孤雌激活后，解冻后的卵母细胞用 MCU-i4 孵育不会改变卵裂和囊胚率。此外，用 DS16570511 孵育解冻后的卵母细胞会降低卵裂和囊胚率。
MII 期卵母细胞玻璃化后 MICU1 介导的线粒体钙摄取增加促进了丙酮酸氧化，这一过程可能通过补偿应激状态下 ATP 的消耗来维持卵母细胞的发育能力。
