College of Veterinary Medicine, Northwest A&F University, Yangling, China.
Beijing Shunxin Xinyuan Research Institute of Cattle Breeding, Beijing, China.
Reprod Domest Anim. 2020 Jul;55(7):822-832. doi: 10.1111/rda.13690. Epub 2020 May 18.
Epidermal growth factor (EGF) is one of the important regulatory factors of EGF family. EGF has been indicated to effectively inhibit the apoptosis of follicular cells, to promote the proliferation of granulosa cells and the maturation of oocytes, and to induce ovulation process via binding to epidermal growth factor receptor (EGFR). However, little is known about the distribution and expression of EGF and EGFR in cattle ovary especially during oestrous cycle. In this study, the localization and expression rule of EGF and EGFR in cattle ovaries of follicular phase and luteal phase at different time points in oestrous cycle were investigated by using IHC and real-time qPCR. The results showed that EGF and EGFR in cattle ovary were mainly expressed in granulosa cells, cumulus cells, oocytes, zona pellucida, follicular fluid and theca folliculi externa of follicles. The protein and mRNA expression of EGF/EGFR in follicles changed regularly with the follicular growth wave both in follicular and in luteal phase ovaries. In follicular phase ovaries, the protein expression of EGF and EGFR was higher in antral follicles than that of those in other follicles during follicular growth stage, and the mRNA expression of EGFR was also increased in stage of dominant follicle selection. However, in luteal phase ovaries, the growth of follicles was impeded during corpus luteum development under the action of progesterone secreted by granular lutein cell. The mRNA and protein expressions of EGF and EGFR in ovarian follicles during oestrous cycle indicate that they play a role in promoting follicular development in follicular growth waves and mediating the selection process of dominant follicles.
表皮生长因子（EGF）是 EGF 家族的重要调节因子之一。研究表明，EGF 通过与表皮生长因子受体（EGFR）结合，能有效抑制卵泡细胞凋亡，促进颗粒细胞增殖和卵母细胞成熟，并诱导排卵过程。然而，关于 EGF 和 EGFR 在牛卵巢中的分布和表达，特别是在发情周期中，人们知之甚少。本研究采用免疫组织化学和实时 qPCR 技术，研究了 EGF 和 EGFR 在发情周期不同时间点卵泡期和黄体期牛卵巢中的定位和表达规律。结果表明，EGF 和 EGFR 在牛卵巢中主要表达于卵泡的颗粒细胞、卵丘细胞、卵母细胞、透明带、卵泡液和卵泡外膜。EGF/EGFR 的蛋白和 mRNA 表达在卵泡期和黄体期卵巢中均随卵泡生长波而规律变化。在卵泡期卵巢中，在卵泡生长阶段，窦前卵泡中 EGF 和 EGFR 的蛋白表达高于其他卵泡，在优势卵泡选择阶段，EGFR 的 mRNA 表达也增加。然而，在黄体期卵巢中，颗粒黄体细胞分泌的孕激素作用下，黄体发育阻碍了卵泡的生长。发情周期中卵巢卵泡中 EGF 和 EGFR 的 mRNA 和蛋白表达表明，它们在促进卵泡生长波中的卵泡发育和调节优势卵泡选择过程中发挥作用。
