GPR50 participates in and promotes yak oocyte maturation: A new potential oocyte regulatory molecule

Numerous molecular regulatory mechanisms are involved in the formation of mammalian oocytes, but many of their key proteins and molecules remain unknown. GPR50, the lone G protein-coupled receptor located in the X chromosome, is one of the superfamily members of the G protein-coupled receptor. GPR50 has been recently proved to play an important role in various physiological activities. However, the role of GPR50 in reproduction is currently unclear. In our previous research, we proved that the GPR50 receptor is present in yak oocytes. In the present study, the expression level and subcellular localization of GPR50 in the in vitro maturation process of yak oocytes were investigated to explore further its role in the maturation of yak oocytes. In the germinal vesicle (GV) stage, GPR50 was expressed and positioned in the cell membrane. By comparison, in the metaphase II (MII) stage, GPR50 had the highest expression level and was highly diffused in the cytoplasm. On the basis of these observations, the knockdown and overexpression of GPR50 yak oocyte models were constructed. Results showed that the expression level of GPR50 knockdown significantly reduced the excretion rate and maturity level of the yak oocyte PB1 (P < 0.01). However, the expression level of GPR50 overexpression exerted no significant influence on the excretion rate and maturity level of the yak oocytes (P > 0.05). This study verified that GPR50 plays an important role in the in vitro maturation process of yak oocytes.