Futuristic Animal Resource & Research Center, Korea Research Institute of Bioscience and Biotechnology, Chungcheongbuk-do, Republic of Korea.
National Primate Research Center, Korea Research Institute of Bioscience and Biotechnology, Chungcheongbuk-do, Republic of Korea.
PLoS One. 2018 Oct 11;13(10):e0205495. doi: 10.1371/journal.pone.0205495. eCollection 2018.
Successful production of transgenic pigs requires oocytes with a high developmental competence. However, cumulus-oocyte complexes (COCs) obtained from antral follicles have a heterogeneous morphology. COCs can be classified into one of two classes: class I, with five or more layers of cumulus cells; and class II, with one or two layers of cumulus cells. Activator [e.g., epidermal growth factor (EGF)] or inhibitors (e.g., wortmannin and U0126) are added to modulate kinases in oocytes during meiosis. In the present study, we investigated the effects of kinase modulation on nuclear and cytoplasmic maturation in COCs. Class I COCs showed a significantly higher developmental competence than class II COCs. Moreover, the expression of two kinases, AKT and ERK, differed between class I and class II COCs during in vitro maturation (IVM). Initially, inhibition of the PI3K/AKT signaling pathway in class I COCs during early IVM (0-22 h) decreased developmental parameters, such as blastocyst formation rate, blastomere number, and cell survival. Conversely, EGF-mediated AKT activation in class II COCs enhanced developmental capacity. Regarding the MAPK signaling pathway, inhibition of ERK by U0126 in class II COCs during early IVM impaired developmental competence. However, transient treatment with U0126 in class II COCs increased oocyte maturation and AKT activity, improving embryonic development. Additionally, western blotting showed that inhibition of ERK activity negatively regulated the AKT signaling pathway, indicative of a relationship between AKT and MAPK signaling in the process underlying meiotic progression in pigs. These findings may help increase the developmental competence and utilization rate of pig COCs with regard to the production of transgenic pigs and improve our understanding of kinase-associated meiosis events.
成功生产转基因猪需要具有高发育能力的卵母细胞。然而，从腔前卵泡中获得的卵丘-卵母细胞复合物（COC）具有异质形态。COC 可分为两类之一：I 类，具有 5 个或更多层的卵丘细胞；II 类，具有 1 个或 2 个层的卵丘细胞。激活剂（例如表皮生长因子（EGF））或抑制剂（例如wortmannin 和 U0126）被添加到卵母细胞中以在减数分裂过程中调节激酶。在本研究中，我们研究了激酶调节对 COC 核和细胞质成熟的影响。I 类 COC 表现出比 II 类 COC 更高的发育能力。此外，在体外成熟（IVM）过程中，两种激酶 AKT 和 ERK 的表达在 I 类和 II 类 COC 之间存在差异。最初，在早期 IVM（0-22 小时）期间抑制 I 类 COC 中的 PI3K/AKT 信号通路会降低发育参数，例如囊胚形成率、卵裂球数和细胞存活率。相反，EGF 介导的 II 类 COC 中的 AKT 激活增强了发育能力。关于 MAPK 信号通路，在早期 IVM 期间 U0126 抑制 II 类 COC 中的 ERK 会损害发育能力。然而，在 II 类 COC 中短暂处理 U0126 会增加卵母细胞成熟和 AKT 活性，从而改善胚胎发育。此外，Western 印迹显示 ERK 活性的抑制负调节 AKT 信号通路，表明在猪减数分裂进展过程中 AKT 和 MAPK 信号之间存在关系。这些发现可能有助于提高转基因猪生产中猪 COC 的发育能力和利用率，并提高我们对与激酶相关的减数分裂事件的理解。
