NCBI Summary:
microRNAs (miRNAs) are short (20-24 nt) non-coding RNAs that are involved in post-transcriptional regulation of gene expression in multicellular organisms by affecting both the stability and translation of mRNAs. miRNAs are transcribed by RNA polymerase II as part of capped and polyadenylated primary transcripts (pri-miRNAs) that can be either protein-coding or non-coding. The primary transcript is cleaved by the Drosha ribonuclease III enzyme to produce an approximately 70-nt stem-loop precursor miRNA (pre-miRNA), which is further cleaved by the cytoplasmic Dicer ribonuclease to generate the mature miRNA and antisense miRNA star (miRNA*) products. The mature miRNA is incorporated into a RNA-induced silencing complex (RISC), which recognizes target mRNAs through imperfect base pairing with the miRNA and most commonly results in translational inhibition or destabilization of the target mRNA. The RefSeq represents the predicted microRNA stem-loop. [provided by RefSeq, Sep 2009]
General function
RNA metabolism, RNA processing
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Cellular localization
Cytoplasmic
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Ovarian function
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Expression regulated by
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Ovarian localization
Cumulus
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Identification of altered microRNAs and mRNAs in the cumulus cells of PCOS patients. Huang X et al. (2016) Polycystic ovary syndrome (PCOS) is a common endocrine and metabolic disorder in women and is characterised by polycystic ovaries, hyperandrogenism, and chronic anovulation. Although the clinical and biochemical signs of PCOS are typically heterogeneous, abnormal folliculogenesis is considered a common characteristic of PCOS. Our aim was to identify the altered miRNA and mRNA expression profiles in the cumulus cells of PCOS patients to research their molecular function in the aetiology and pathophysiology of PCOS. In the present study, the miRNA expression profiles of the cumulus cell samples isolated from five PCOS and five control patients were determined by a miRNA microarray. At the same time, the altered mRNA profiles of the same cumulus cells samples were also identified by a cDNA microarray. From the microarrays data, 17 miRNAs and 1263 mRNAs showed significantly different expression in the PCOS cumulus cells. The differentially expressed miRNA-509-3p and its potential target gene (MAP3K8) were identified from the miRNA and mRNA microarrays, respectively. The expression of miR-509-3p was up-regulated, and MAP3K8 was down-regulated, in the PCOS cumulus cells. The direct interaction between miR-509-3p and MAP3K8 was confirmed by a luciferase activity assay in KGN cells. In addition, miR-509-3p mimics or inhibitor transfection tests in KGN cells further confirmed that miR-509-3p improved E2 secretion by inhibiting the expression of MAP3K8. These results help to characterise the pathogenesis of anovulation in PCOS, especially the regulation of oestradiol production.//////////////////