Proteomic analysis reveals changes in protein expression in yak oocytes at different meiosis stages.

Oocyte maturation requires close cooperation among multiple kinases and growth factors. However, the proteome landscape during yak oocyte maturation has not yet been characterized. Here, 4D-DIA (data independent acquisition) technology was used to sequence the proteome of yak oocytes at four stages, germinal vesicle (GV), germinal vesicle breakdown (GVBD), meiosis I (MI), and meiosis II (MII), and 5851 proteins were identified. During the transition from GV to GVBD, more proteins are activated to stimulate germinal vesicle breakdown. From MI to MII, the expression of most proteins was down-regulated. Bioinformatics analysis showed that GV oocytes contained a large number of proteins related to energy metabolism. The proteins in GVBD oocytes were mainly related to the activity of enzyme inhibitors. MII oocytes contained keratin family members and proteins involved in cell cycle regulation. In addition, it was found that the expression of phosphorylation modification enzymes and ubiquitination modification enzymes change dynamically during oocyte maturation. Parallel reaction monitoring (PRM) validated the expression of key differentially expressed proteins. These results provide important information for enhancing the understanding of the molecular mechanism of oocyte maturation and improving the efficiency of the in vitro maturation of yak oocytes, which are critically important for enhancing the reproductive efficiency of yak.