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 binding
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Cellular localization
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Ovarian function
Follicle atresia, Steroid metabolism
Comment
MicroRNA-205 affects mouse granulosa cell apoptosis and estradiol synthesis by targeting CREB1. Zhang P et al. (2018) MicroRNA-205 (miR-205) is involved in various physiological and pathological processes, but its biological function in follicular atresia remains unclear. In this study, we investigated miR-205 expression in mouse granulosa cells (mGCs) and analyzed its functions in primary mGCs by performing a series of in vitro experiments. Quantitative real-time polymerase chain reaction showed that miR-205 expression was significantly higher in early atretic follicles and progressively atretic follicles than in healthy follicles. miR-205 overexpression in mGCs significantly promoted apoptosis and caspase-3/9 activities, as well as inhibited estrogen (E2) release and cytochrome P450 family 19 subfamily A polypeptide 1 (CYP19A1, a key gene in E2 production) expression. Bioinformatics and luciferase reporter assays revealed that the gene encoding cyclic AMP response element (CRE)-binding protein 1 (CREB1) was a direct target of miR-205 in mGCs. CREB1 upregulation partially rescued the effects of miR-205 on apoptosis, caspase-3/9 activities, E2 production, and CYP19A1 expression on mGCs. These results indicate that miR-205 might play an important role in ovarian follicular development and provide new insights into follicular atresia.//////////////////
Expression regulated by
Growth Factors/ cytokines, BDNF
Comment
BDNF-induced expansion of cumulus-oocyte complexes in pigs was mediated by microRNA-205. Li C et al. (2016) The neurotrophin family of proteins is required for the survival and differentiation of the nervous system and is important to the development of reproductive tissues. The objectives of the present study were to detect the presence of the brain-derived neurotrophic factor (BDNF) and its tyrosine kinase receptor protein in cumulus-oocyte complexes in pigs and to explore the role of microRNAs in the BDNF-induced in vitro maturation of oocytes. We demonstrate that both BDNF and tyrosine kinase receptor protein are expressed in porcine cumulus oocyte complexes. BDNF supplementation promotes the in vitro maturation of porcine oocytes. MiRNA-205 is downregulated during the BDNF-induced maturation of oocytes. The overexpression of miRNA-205 in granulosa cells and reporter gene assay shows that the marker gene ptx3 for cumulus expansion is the putative target gene of miR-205. Our data provide evidence that the BDNF-induced maturation of oocytes in pigs may be mediated by miR-205 through the regulation of potential target gene, ptx3.//////////////////
Ovarian localization
Oocyte
Comment
Expression analysis of regulatory microRNAs in bovine cumulus oocyte complex and preimplantation embryos. Abd El Naby WS et al. SummaryMicroRNAs (miRNAs) are small endogenous molecules that are involved in a diverse of cellular process. However, little is known about their abundance in bovine oocytes and their surrounding cumulus cells during oocyte development. To elucidate this situation, we investigated the relative expression pattern of sets of miRNAs between bovine oocyte and the surrounding cumulus cells during in vitro maturation using miRNA polymerase chain reaction (PCR) array. Results revealed that a total of 47 and 51 miRNAs were highly abundant in immature and matured oocytes, respectively, compared with their surrounding cumulus cells. Furthermore, expression analysis of six miRNAs enriched in oocyte miR-205, miR-150, miR-122, miR-96, miR-146a and miR-146b-5p at different maturation times showed a dramatic decrease in abundance from 0 h to 22 h of maturation. The expression of the same miRNAs in preimplantation stage embryos was found to be highly abundant in early stages of embryo development and decreased after the 8-cell stage to the blastocyst stage following a typical maternal transcript profile. Similar results were obtained by localization of miR-205 in preimplantation stage embryos, in which signals were higher up to the 4-cell stage and reduced thereafter. miR-205 and miR-210 were localized in situ in ovarian follicles and revealed a spatio-temporal expression during follicular development. Interestingly, the presence or absence of oocytes or cumulus cells during maturation was found to affect the expression of miRNAs in each of the two cell types. Hence, our results showed the presence of distinct sets of miRNAs in oocytes or cumulus cells and the presence of their dynamic degradation during bovine oocyte maturation.