Specific genes are selectively expressed between cumulus and granulosa cells from individual human pre-ovulatory follicles

Abstract

During folliculogenesis, the granulosa cells differentiate into two cell types: cumulus cells (CCs) and mural granulosa cells (MGCs). The objective of the study was to generate and compare the transcriptomes of MGCs and CCs from the pre-ovulatory follicle to characterize the detailed profile of the two cell populations shortly before ovulation. Twenty-one IVF/ICSI patients undergoing controlled ovarian stimulation (COS) donated CCs and MGCs from individual follicles containing metaphase II oocytes. Cells were prepared immediately after recovery and mRNA was isolated for whole-genome gene expression analysis and reverse transcriptase-polymerase chain reactions. Paired (within the individual follicle) comparisons between the CC and MGC expression profiles were performed and corrected for multiple comparisons. A total of 1562 genes were differentially expressed by >2-fold (P < 0.01) in the two cell types. Of these, 156 genes were >8-fold changed and represented specialized cellular functional categories such as inflammatory response, extracellular matrix and cell-cell communication, whereas the 1406 genes were 2-8-fold changed and represented functional categories such as proliferation and lipid metabolism. Transcripts not previously linked to the follicle were found to be differentially expressed between CCs and MGCs, suggesting specialized function in these compartments, e.g. pepsinogen A was selectively expressed in MGCs, whereas ryanodine receptor-2 (RYR2) was selectively expressed in CCs. Positive correlations were present between expression levels of RYR2 and the amphiregulin and gap-junction proteins. In conclusion, the transcriptomes of corresponding CCs and MGCs from individual pre-ovulatory follicles clearly revealed two distinct cell types. New as well as known genes representing specific cell functions close to ovulation were highlighted.

Research Resources: Comparative MicroRNA Profiles in Human Corona Radiata Cells and Cumulus Oophorus Cells Detected by Next-Generation Small RNA Sequencing

“…MiR-383 promotes steroidogenesis by targeting RBMS1 via the inactivation of c-Myc [19]. These studies suggest that miRNAs are involved in the regulation of granulosa cell-related biological processes during folliculogenesis and emphasise the importance of the comparative identification of the miRNA profiles in CRCs and COCs [20]–[23].…”

No Specific Gene Expression Signature in Human Granulosa and Cumulus Cells for Prediction of Oocyte Fertilisation and Embryo Implantation

“…With the inclusion of patients with tubal or unexplained cause of infertility, we excluded the possibility of gene expression differences deriving from primary disease such as PCO [36] or endometriosis [37, 38]. By analyzing individual GC and CC samples, we have gained detailed information about gene expression for each individual follicle, as it is known that pooling of samples can mask the detailed intrafollicular conditions [39]. Additionaly, by elective single embryo transfer we precisely knew which embryo did and which did not implant.…”

Characterization of the human cumulus cell transcriptome during final follicular maturation and ovulation

“…An increasing number of human studies have shown correlations of CC gene expression with oocyte maturation, fertilization rate (McKenzie et al, 2004) and pregnancy outcome (Feuerstein et al, 2007;Hamel et al, 2008;Assou et al, 2010). However, all of these studies have used only CCs from pre-ovulatory follicles that were previously exposed to human chorionic gonadotrophin (hCG) (Kenigsberg et al, 2009;de los Santos et al, 2012;Grondahl et al, 2012) or CC derived from cumulus oocyte complexes (COCs) matured in vitro (Ouandaogo et al, 2012). We were unable to find any human study aimed at discerning differences in CC gene expression between immature COC derived from mid-antral follicles and COC obtained from mature follicles.…”