Differential miRNA Expression Profiles in Cumulus and Mural Granulosa Cells from Human Pre-ovulatory Follicles

BACKGROUND: Mural Granulosa Cells (MGCs) and Cumulus Cells (CCs) are two specialized cell types that differentiate from a common progenitor during folliculogenesis. Although these two cell types have specialized functions and gene expression profiles, little is known about their microRNA (miRNA) expression patterns. OBJECTIVE: To describe the miRNA profile of mural and cumulus granulosa cells from human pre-ovulatory follicles. METHODS: Using small RNA sequencing, we defined the miRNA expression profiles of human primary MGCs and CCs, isolated from healthy women undergoing ovum pick-up for in vitro Fertilization (IVF). RESULTS: Small RNA sequencing revealed the expression of several hundreds of miRNAs in MGCs and CCs with 53 miRNAs being significantly differentially expressed between MGCs and CCs. We validat-ed the differential expression of miR-146a-5p, miR-149-5p, miR-509-3p and miR-182-5p by RT-qPCR. Analysis of proven targets revealed 37 targets for miR-146a-5p, 43 for miR-182-5p, 2 for miR-509-3p and 9 for miR-149-5p. Gene Ontology (GO) analysis for these 4 target gene sets revealed enrichment of 12 GO terms for miR-146a-5p and 10 for miR-182-5p. The GO term ubiquitin-like protein conjugation was enriched within both miRNA target gene sets. CONCLUSION: We generated miRNA expression profiles for MGCs and CCs and identified several dif-ferentially expressed miRNAs.