105 Proteome profiling of equine follicular fluid before, during, and after selection of the dominant follicle.

This research aimed to understand the signalling coordination of follicle cells during the selection and development of dominant ovulatory follicles in horses, by analyzing the proteome profiles of follicular fluid at different stages. The study identified a total of 294 unique proteins in the fluid, some of which might play key roles in the selection, dominance, and ovulation of the follicle.

Objective of the Research

• The main goal of this study was to provide a better understanding of the selection mechanism and development of the dominant ovulatory follicle in horses. This was accomplished by conducting proteome profiling and comparison of follicular fluid collected in vivo. The knowledge gained from this study potentially aids in improving assisted reproductive technologies.

Methodology

• A new follicular wave was induced in 17 mares, and follicle growth was tracked daily using ultrasonography. This process was done by applying ablation to all follicles that were greater than or equal to 6 mm during mid-cycle.
• Follicular fluid was then aspirated at different stages: Predeviation (when follicles reached a size of 18-20 mm), Deviation or selection (22-25 mm), Postdeviation (26-29 mm), Preovulatory (30-35 mm), and Impending signs of ovulation (more than 35 mm).
• Once harvested, the follicular fluid samples were immediately processed through centrifugation and stored at -80°C until further analysis. The analysis was done through proteomic shotgun methodology, using nanoLC-MS/MS and protein identification.

Findings

• A total of 294 unique proteins were identified across all the stages, with a certain count of proteins being common and others differing across the stages.
• These proteins were categorized into the classical biological categorisations: cellular component (CC), molecular function (MF), and biological processes (BP).
• Enriched gene ontologies were identified in the CC, MF, and BP domains, with certain ontologies being significantly and differentially enriched during follicle development.
• The complement and coagulation cascades were found to be the significantly enriched Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways during follicle development.
• Ultimately, 43 differentially expressed proteins were identified as potentially playing key roles in follicle selection, dominance, and ovulation.

Inference

• This research helped establish that certain proteins in the follicular fluid play critical roles in regulating follicle development and behaviour.
• The outcomes from this study could help in discovering potential biomarkers for improving assisted reproductive technologies.