Comprehensive proteomic profiling of early antral follicles from sheep

The present study evaluates the proteome of early antral follicles in Ovis aries. Fifty follicles were collected from ovaries of adult ewes and extracted proteins were trypsin-digested, desalted and analyzed by LC-MS/MS. Peptide-spectrum search was performed using PatternLab V. Genes were screened for potential modulation by miRNAs and protein data, subjected to functional enrichment analysis. Label-free LC-MS/MS allowed the identification of 2,503 proteins in the samples of early antral follicles, confirming vimentin, actin, lamin, heat shock proteins and histones as the most abundant ones. miRNAs modulate the expression of genes involved in cell cycle, cell differentiation, aging, apoptosis, cell death, adipocyte differentiation, cell division. The most important biological processes linked to the follicle proteins were innate immune response, translation, adaptative immune response and protein folding, while molecular functions linked to the proteome of sheep antral follicles related to metal ion binding, ATP binding, oxygen binding, RNA binding and GTP binding, among others. Upload of 2,503 Uniprot accession codes through DAVID platform matched 1,274 genes, associated with translation, metabolic process, proteolysis involved in cellular protein catabolic process, zona pellucida receptor complex and others. KEEG pathways established from the DAVID analysis indicated genes correlated with ovine follicle development, with major pathways listed as carbon metabolism, biosynthesis of amino acids, glutathione metabolism, oxidative phosphorylation, fatty acid degradation and oocyte meiosis. This represents the most comprehensive atlas of proteins expressed in sheep early antral follicles. Data will contribute to future identification of genes and proteins involved in ovine follicular development and oocyte maturation.