Expression of microRNAs and their target genes and pathways associated with ovarian follicle development in cattle

Abstract

Development of ovarian follicles is controlled at the molecular level by several gene products whose precise expression leads to regression or ovulation of follicles. MicroRNAs (miRNAs) are small noncoding RNAs that regulate gene expression through sequence-specific base pairing with target messenger RNAs (mRNAs) causing translation repression or mRNA degradation. The aim of this study was to identify miRNAs expressed in theca and/or granulosa layers and their putative target genes/pathways that are involved in bovine ovarian follicle development. By using miRCURY microarray (Exiqon) we identified 14 and 49 differentially expressed miRNAs (P < 0.01) between dominant and subordinate follicles in theca and granulosa cells, respectively. The expression levels of four selected miRNAs were confirmed by qRT-PCR. To identify target prediction and pathways of differentially expressed miRNAs we used Union of Genes option in DIANA miRPath v.2.0 software. The predicted targets for these miRNAs were enriched for pathways involving oocyte meiosis, Wnt, TGF-beta, ErbB, insulin, P13K-Akt, and MAPK signaling pathways. This study identified differentially expressed miRNAs in the theca and granulosa cells of dominant and subordinate follicles and implicates them in having important roles in regulating known molecular pathways that determine the fate of ovarian follicle development.

In search of the transcriptional blueprints of a competent oocyte

“…In cattle these chip arrays were used to characterize the expression of miRNAs in the oocyte (Tesfaye et al, 2009), ovarian follicle (Sontakke et al, 2014) and cellular components of the ovarian follicle, including theca and granulosa cells (Abd El Naby et al, 2013;Zielak-Steciwko et al, 2014). Since miRNAs are found also outside the cells, interesting resuts were obtained analyzing the follicular fluid, whose miRNA content has been linked to the oocyte growth and may represent potential biomarkers of developmental competence (Sohel et al, 2013).…”

“…Furthermore, miRNAs have also been detected in ovine granulosa and theca cells at different stages of follicle development (McBride et al, 2012); in equine ovaries, they play a role in the regulation of cell survival, steroidogenesis, and follicle differentiation . In cattle, there are a few examples of a differential expression of miRNAs in granulosa cells during folliculogenesis (Zielak-Steciwko et al, 2014;Gebremedhn et al, 2015).…”

“…Data suggest that miRNAs may regulate cellular differentiation during follicular development and may contribute to the oocyte-somatic cells dialog during the acquisition of oocyte developmental competence. In cattle, miRNAs were found in follicular fluid and their profile changes during folliculogenesis (Zielak-Steciwko et al, 2014). They are both free and associated with exosomes; the latter possibly facilitating the transport of specific miRNAs into follicular cells (Sohel et al, 2013).…”

MicroRNAs: New Insight in Modulating Follicular Atresia: A Review

“…Huge numbers of protein coding genes are thought to be regulated by miRNAs, in a process whereby individual miRNAs target multiple genes and an individual gene is targeted by multiple miRNAs [12,13]. Currently, large numbers of miRNAs have been identified and characterized in different species of mammalians’ reproductive tissues and cells [13,14,15,16,17,18,19].…”

“…Huge numbers of protein coding genes are thought to be regulated by miRNAs, in a process whereby individual miRNAs target multiple genes and an individual gene is targeted by multiple miRNAs [12,13]. Currently, large numbers of miRNAs have been identified and characterized in different species of mammalians’ reproductive tissues and cells [13,14,15,16,17,18,19]. They are implicated in various regulatory roles of cellular physiological events including oocyte maturation, apoptosis, proliferation, differentiation, development and biogenesis [17,20,21,22,23,24,25,26,27,28,29,30].…”