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
Cell proliferation, RNA processing
Comment
Cellular localization
Secreted
Comment
Association of single nucleotide polymorphisms in the RAB5B gene 3'UTR region with polycystic ovary syndrome in Chinese Han women. Yu J et al. (2019) Previous genome-wide sequencing revealed that Ras-related protein Rab-5B (RAB5B) is a susceptible target in patients with polycystic ovary syndrome (PCOS). Direct sequencing was performed to analyze the RAB5B gene rs1045435, rs11550558, rs34962186, rs705700, rs58717357, rs11171718, rs60028217, rs772920 loci genotypes in 300 PCOS patients and 300 healthy controls. The plasma microRNA (miRNA)-24, miR-320 levels were measured by reverse transcription fluorescent quantitative PCR (RT-qPCR). The risk of PCOS in C allele carriers of RAB5B gene rs1045435 locus was 3.91 times higher than that of G allele. The risk of PCOS in rs11550558 locus G allele was 4.09 times higher than A allele. The risk of PCOS in rs705700 locus C allele was 1.66 times greater than T allele. The risk of PCOS in rs11171718 locus A allele carrier was 3.84 times higher than G allele. The s11550558 SNP was associated with PCOS risk only in those with age≥31.1 years. And RAB5B gene rs11550558, rs1045435, and rs11171718 SNPs were significantly associated with PCOS risk only in subjects with BMI≥23.8kg/m2 We also found that the RAB5B gene rs1045435 SNP was associated with plasma miR-24 levels. The RAB5B gene rs11550558, rs705700, rs11171718 SNPs were correlated with plasma miR-230 levels. The single nucleotide polymorphisms of the rs1045435, rs11550558, rs705700, and rs11171718 loci of the RAB5B gene are associated with PCOS risk. The rs1045435 locus is likely a miR-24 binding site, while rs11550558, rs705700, and rs11171718 loci may be miR-320 binding sites.//////////////////
Ovarian function
Steroid metabolism
Comment
Proliferation of Ovarian Granulosa Cells in Polycystic Ovarian Syndrome Is Regulated by MicroRNA-24 by Targeting Wingless-Type Family Member 2B (WNT2B). Yuanyuan Z et al. (2019) BACKGROUND Polycystic ovarian syndrome (PCOS) is a common endocrine disorder causing infertility among reproductive-age women. The molecular mechanisms underlying the development of PCOS are not well understood, and effective treatment options and therapeutic targets for PCOS are not available. This study was designed to investigate the role and therapeutic potential of miR-324 in PCOS. MATERIAL AND METHODS We used quantitative real time-polymerase chain reaction (qRT-PCR) to assess expression. Cell viability was determined by [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] (MTT) assay. Acridine orange/ethidium bromide (AO/EB) and annexin V/PI staining were performed to examine apoptosis. Western blot analysis was used to determine protein expression. RESULTS Results showed that the expression of miR-324 was aberrantly and significantly downregulated in PCOS ovarian tissues and KGN ovarian granulosa cells. Nonetheless, ectopic expression of miR-324 expression inhibited the viability of KGN cells via induction of apoptotic cell death. In silico analysis showed Wingless-Type family member 2B (WNT2B) to be the target of miR-324, which was also validated by dual-luciferase reporter assay. We also found that the expression of WNT2B was upregulated in the KGN cells, and overexpression of miR-324 inhibited WNT2B expression. Similar to WNT2B overexpression, WNT2B silencing decreased the viability of the KGN. Furthermore, overexpression of WNTB2 in KGN partially reversed the growth-inhibitory effects of miR-324 overexpression. CONCLUSIONS miR-324 regulates the proliferation of KGN cells in PCOs and be essential in the management of PCOS.//////////////////
Expression regulated by
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Ovarian localization
, Follicular Fluid
Comment
Identification of microRNAs in human follicular fluid: characterization of microRNAs that govern steroidogenesis in vitro and are associated with polycystic ovary syndrome in vivo. Sang Q et al. Context:Human follicular fluid is a combination of proteins, metabolites, and ionic compounds that is indicative of the general state of follicular metabolism and is associated with maturation and quality of oocytes. Deviations in these components are often associated with reproductive diseases. There has been no report of microRNAs (miRNAs) in human follicular fluids.Objective:We hypothesized that human follicular fluid may contain miRNAs. We sought to identify cell-free miRNAs in human follicular fluid and to investigate these miRNAs's function in vitro and any roles they play in polycystic ovary syndrome.Design:Genome-wide deep sequencing and TaqMan miRNA arrays were used to identify miRNAs, and the roles of the highly expressed miRNAs in steroidogenesis were investigated in KGN cells. Quantification of candidate miRNAs in follicular fluids of PCOS and controls was performed using TaqMan miRNA assays.Results:We identified miRNAs in microvesicles and the supernatant of human follicular fluid. Bioinformatics analysis showed that the most highly expressed miRNAs targeted genes associated with reproductive, endocrine, and metabolic processes. We found that miR-132, miR-320, miR-520c-3p, miR-24, and miR-222 regulate estradiol concentrations and that miR-24, miR-193b, and miR-483-5p regulate progesterone concentrations. Finally, we showed that miR-132 and miR-320 are expressed at significantly lower levels in the follicular fluid of polycystic ovary patients than in healthy controls (p =0.005, p =0.0098, respectively)Conclusion:These results demonstrate that there are numerous miRNAs in human follicular fluids, some of which play important roles in steroidogenesis and PCOS. This study substantially revises our understanding of the content of human follicular fluid and lays the foundation for the future investigation of miRNAs' role in PCOS.