Gao Lei, Hou Yunpeng, Zeng Shenming, Li Junyou, Zhu Shien, Fu Xiangwei
National Engineering Laboratory for Animal Breeding and Key Laboratory of Animal Genetics, Breeding and Reproduction, Ministry of Agriculture, College of Animal Science and Technology, China Agricultural University, Beijing, China.
State Key Laboratory for Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, China.
Front Cell Dev Biol. 2020 Jul 9;8:621. doi: 10.3389/fcell.2020.00621. eCollection 2020.
Oocytes vitrification is frequently applied in assisted reproductive technologies. However, chromosomes segregation was error-prone during meiosis maturation of vitrified oocytes. The fidelity of chromosomes segregation depends on the correct kinetochore-microtubule attachments (KT-MTs). In meiosis I, the Aurora B/C would not spatially separate from the attachment sites upon bivalents stretched. Oocytes lack a mechanism for coordinating bivalent stretching and Aurora B/C inhibition in meiosis I. Thus, the KT-MTs are unstable in oocytes. In this study, we firstly found the incorrect KT-MTs were markedly increased in vitrified oocytes. The Aurora B/C activity in vitrified oocytes was significantly increased when the bivalents were stretched. This Aurora B/C activity could not induce a SAC response, as the SAC protein Mad2 was significantly decreased during MI stage in vitrified oocytes. Thus, the KT-MTs in vitrified oocytes were error-prone. This study, for the first time, revealed the mechanism of the incorrect KT-MTs occurred in vitrified oocytes and provided a theoretical basis for further improvement of oocytes vitrification.
卵母细胞玻璃化冷冻技术在辅助生殖技术中应用广泛。然而，玻璃化冷冻的卵母细胞在减数分裂成熟过程中染色体分离容易出错。染色体分离的准确性取决于正确的动粒-微管附着（KT-MTs）。在减数第一次分裂中，当二价体伸展时，极光激酶B/C（Aurora B/C）不会在空间上与附着位点分离。卵母细胞缺乏在减数第一次分裂中协调二价体伸展和抑制极光激酶B/C的机制。因此，卵母细胞中的KT-MTs不稳定。在本研究中，我们首次发现玻璃化冷冻的卵母细胞中不正确的KT-MTs显著增加。当二价体伸展时，玻璃化冷冻卵母细胞中的极光激酶B/C活性显著增加。这种极光激酶B/C活性不能诱导纺锤体组装检查点（SAC）反应，因为在玻璃化冷冻卵母细胞的减数第一次分裂阶段，SAC蛋白Mad2显著减少。因此，玻璃化冷冻卵母细胞中的KT-MTs容易出错。本研究首次揭示了玻璃化冷冻卵母细胞中不正确的KT-MTs产生的机制，为进一步改进卵母细胞玻璃化冷冻技术提供了理论依据。
