Proteomic analysis implicates that postovulatory aging leads to aberrant gene expression, biosynthesis, RNA metabolism and cell cycle in mouse oocytes

Background In mammals, oocytes display compromised quality after experiencing a process of postovulatory aging. However, the mechanisms underlying are not yet fully understood. Here, we portrayed a protein expression profile of fresh and aging metaphase II (MII) mouse oocytes by means of four-dimensional label-free quantification mass spectrometry (4D-LFQ). Results The analysis of 4D-LFQ data illustrated that there were seventy-six differentially expressed proteins (DEPs) between two groups of MII stage oocytes. Fifty-three DEPs were up-regulated while twenty-three DEPs were down-regulated in the MII oocytes of the aging group, and Gene Ontology (GO) analysis revealed that these DEPs were mainly enriched in regulation of gene expression, biosynthesis, RNA metabolism and cell cycle. Our detailed analysis revealed that the expression of proteins that related to gene expression processes such as transcription, translation, post-translational modifications and epigenome was changed; the relative protein expression of RNA metabolic processes, such as RNA alternative splicing, RNA export from nucleus and negative regulation of transcription from RNA polymerase II promoter was also altered. Conclusion In conclusion, we identified considerable DEPs and discussed how they agreed with previous researches illustrating altered protein expression associated with the quality of oocytes. Our research provided a new perspective on the mechanisms of postovulatory aging and established a theoretical support for practical methods to control and reverse postovulatory aging.

Automated summary

By analyzing the protein expression profile of fresh and aging metaphase II mouse oocytes using four-dimensional label-free quantification mass spectrometry, we identified differential expression of proteins related to gene expression and RNA metabolism. These findings provide a new perspective on the mechanisms of postovulatory aging.