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MiRNA expression profile in relation to oocyte developmental competence

ABSTRACT: The objective of this study was to identify the expression profile of miRNAs in porcine oocytes derived from follicles of different sizes using RNA high throughput sequencing technology. Oocytes were aspirated from large (3-6 mm) or small (<2 mm) ovarian follicles and tested for developmental competence and chromatin configurations. Small RNA libraries were constructed from both groups and then sequenced on an Illumina NextSeq500. Oocytes from large follicles showed higher developmental competence and different chromatin configuration compared to small oocyte group. In total, 167 and 162 known miRNAs were detected in large and small oocyte groups, respectively with 153 miRNAs were commonly expressed in both groups. In addition, 155 predicted novel miRNAs were detected and quantified. MiR-205, miR-16, miR-148a-3p, miR-125b, and let-7 family were among the top 10 highly abundantly expressed miRNAs in both oocyte groups. Further analysis showed that 8 miRNAs were differentially expressed (DE) between both groups (>2 fold change) with 4 up- and 4 down-regulated miRNAs in large compared to small oocyte group. Target gene prediction followed by KEGG pathway analysis revealed 46 pathways that were enriched with miRNA-target genes. Oocyte meiosis pathway and signaling pathways including FoxO, PI3K-Akt, TGFβ, and cAMP were predictably targeted by DE miRNAs. These results give more insights into the potential role of miRNAs in controlling oocyte developmental competence.

ORGANISM(S): Sus scrofa

PROVIDER: GSE122032 | GEO | 2019/02/13

REPOSITORIES: GEO

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Project description:MicroRNAs (miRNAs) are small noncoding RNAs that regulate gene expression primarily at the post-transcriptional levels and thereby play important roles in regulating many physiological and developmental processes. Oocyte maturation in fish is induced by hormones produced from the hypothalamus, pituitary, and ovary. Gonadotropin-releasing hormone (GnRH) stimulates the secretion of luteinizing hormone (LH), which in turn, induces the secretion of maturation-inducing hormone (MIH) from the ovary. It is documented that small early vitellogenic (or stage IIIa) follicles are unable to undergo oocyte maturation whereas oocytes in mid- to late vitellogenic (stage IIIb) follicles can be induced by LH and MIH to become mature. To determine whether miRNAs may be involved in the growth and acquisition of maturational competency of ovarian follicles, we determined the miRNA expression profiles in follicular cells collected from stage IIIa and IIIb follicles using next-generation sequencing. It was found that miRNAs are abundantly expressed in the follicular cells from both stages IIIa and IIIb follicles. Furthermore, bioinformatics analysis revealed the presence of 214 known, 31 conserved novel and 44 novel miRNAs in zebrafish vitellogenic ovarian follicular cells. Most mature miRNAs in follicular cells were found to be in the length of 22 nucleotides. Differential expression analysis revealed that 11 miRNAs were significantly up-regulated, and 13 miRNAs were significantly down-regulated in the stage IIIb follicular cells as compared with stage IIIa follicular cells. The expression of four of the significantly regulated miRNAs, dre-miR-22a-3p, dre-miR-16a, dre-miR-181a-3p, and dre-miR-29a, was validated by real-time PCR. Finally, gene enrichment and pathway analyses of the predicted targets of the significantly regulated miRNAs supported the involvement of several key signaling pathways in regulating ovarian function, including oocyte maturation. Taken together, this study identifies novel zebrafish miRNAs and characterizes miRNA expression profiles in somatic cells within the zebrafish ovarian follicles. The differential expression of miRNAs between stage IIIa and IIIb follicular cells suggests that these miRNAs are important regulators of zebrafish ovarian follicle development and/or oocyte maturation.

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MiRNA expression profile in relation to oocyte developmental competence

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