Cumulus cells orchestrate oocyte maturation via actin polymerization and vitamin B₆ metabolism regulation: Highlights...

It is well known that cumulus cells play a crucial role in meiotic resumption and oocyte maturation. However, the role of cumulus cells in oocytes development under vitrification stress remains elusive. Therefore, we sought to delineate the molecular mechanism underlying the interaction of cumulus cells and oocytes developmental potential under stress conditions by integration analysis (Pathway co-enrichment, Protein network clustering, and Pearson correlation analysis) based on 4D Label free proteome, Ultra-Low RNA-seq and untargeted metabolome techniques. "Regulation of actin cytoskeleton" and "vitamin B₆ metabolism" were identified as the most enriched and impacted pathways. Moreover, our results showed that the absence of cumulus cells significantly reduced oocyte survival, maturation, and normal F-actin distribution rate after IVM. Notably, Narciclasine (an agent functions in promoting actin polymerization) significantly improved the polar body extrusion (PBE) rate and reduced cortical tension defects rate of vitrified oocytes after in vitro maturation (IVM). What's more, we discovered that vitrification significantly reduced mitochondrial membrane potential (MMP) level in cumulus cells and ATP content in oocytes. Whereas, Pyridoxal 5'-phosphate monohydrate (the active form of vitamin B₆) improved ATP level and cytoplasmic maturation of vitrified oocytes after IVM. In conclusion, our results demonstrated the value of multi-omics approach in deciphering the role of cumulus cells during ovine oocyte growth under stress conditions, and revealed that promoting actin polymerization and vitamin B₆ metabolism contributes to the improvement of vitrified ovine oocytes quality.