Research resource: small RNA-seq of human granulosa cells reveals miRNAs in FSHR and aromatase genes

Abstract

The granulosa cells in the mammalian ovarian follicle respond to gonadotropin signaling and are involved in the processes of folliculogenesis and oocyte maturation. Studies on gene expression and regulation in human granulosa cells are of interest due to their potential for estimating the oocyte viability and in vitro fertilization success. However, the posttranscriptional gene expression studies on micro-RNA (miRNA) level in the human ovary have been scarce. The current study determined the miRNA profile by deep sequencing of the 2 intrafollicular somatic cell types: mural and cumulus granulosa cells (MGCs and CGCs, respectively) isolated from women undergoing controlled ovarian stimulation and in vitro fertilization. Altogether, 936 annotated and 9 novel miRNAs were identified. Ninety of the annotated miRNAs were differentially expressed between MGCs and CGCs. Bioinformatic prediction revealed that TGFβ, ErbB signaling, and heparan sulfate biosynthesis were targeted by miRNAs in both granulosa cell populations, whereas extracellular matrix remodeling, Wnt, and neurotrophin signaling pathways were enriched among miRNA targets in MGCs. Two of the nine novel miRNAs found were of intronic origin: one from the aromatase and the other from the FSH receptor gene. The latter miRNA was predicted to target the activin signaling pathway. In addition to revealing the genome-wide miRNA signature in human granulosa cells, our results suggest that posttranscriptional regulation of gene expression by miRNAs could play an important role in the modification of gonadotropin signaling. miRNA expression studies could therefore lead to new prognostic markers in assisted reproductive technologies.

Figure 1.

Hairpin Structures and Graphical Representations of pre-miRNA Genomic Locations for Novel miRNAs on Chr2.1, Chr15.1a and 15.1b. A, Hairpin structure of miRNA on Chr2.1. B: Graphical representation of FSHR gene. The transcription site for miRNA on Chr2.1 in the intronic region is marked in red. C and D: Two possible hairpin structures for miRNA on Chr15.1 noted as Chr15.1a and 15.1b. E: Two possible genomic locations for miRNA on Chr15.1 in the intronic region of CYP19A1 gene. Genomic location of miRNA on Chr15.1a is marked in red and Chr15.1b in blue in the subset.

Figure 2.

Sequence Alignment between miRNA on Chr2.1 (shaded) and Four Members of the hsa-miR-548 Family. BLASTN score for each pair-wise alignment with Chr2.1 was 78 and e-value was 0.2.