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
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Cellular localization
Cytoplasmic
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Ovarian function
Antral follicle growth
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MicroRNA-183~96~182 Cluster Regulate Bovine Granulosa Cell Proliferation and Cell Cycle Transition by Coordinately Targeting FOXO1. Gebremedhn S et al. (2016) Large-scale expression profiling of microRNAs (miRNAs) in bovine granulosa cells from dominant and subordinate follicles on Day 19 of the estrous cycle revealed enriched microRNA-183~96~182 (miR-183~96~182) cluster miRNAs in preovulatory dominant follicles that coordinately regulate the forkhead box protein O1 (FOXO1) gene. However, little is known about the role of this cluster in bovine granulosa cell function. We employed an in vitro granulosa cell culture model to investigate this role. Granulosa cells aspirated from small growing follicles (3-5 mm in diameter) were cultured in DMEM/F-12 medium supplemented with Fetal Bovine Serum (FBS) and transfected with Locked Nucleic Acid (LNA)-based miRNA mimics, inhibitors, and the corresponding negative controls. The overexpression of the miRNA cluster resulted in the suppression of FOXO1 mRNA and protein, while inhibition of the cluster increased the expression of FOXO1 mRNA. Overexpression also increased the relative rate of cell proliferation, while inhibition slowed it down. Similarly, the proportion of cells under G0/G1 arrest declined, while the ratio of cells in the S phase increased in response to miR-183~96~182 overexpression. Selective knockdown of FOXO1 mRNA using anti-FOXO1 small interfering RNA (siRNA) increased the rate of granulosa cell proliferation, decreased the proportion of cells under G0/G1 arrest, and increased the proportion of cells in the S phase of the cell cycle. Our data suggest that miR-183~96~182 cluster miRNAs promote proliferation and G1/S transition of bovine granulosa cells by coordinately targeting FOXO1, suggesting a critical role in granulosa cell function.//////////////////
Expression regulated by
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Ovarian localization
Granulosa
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MicroRNA Expression Profile in Bovine Granulosa Cells of Preovulatory Dominant and Subordinate Follicles during the Late Follicular Phase of the Estrous Cycle. Gebremedhn S et al. (2015) In bovine, ovarian follicles grow in a wave-like fashion with commonly 2 or 3 follicular waves emerging per estrous cycle. The dominant follicle of the follicular wave which coincides with the LH-surge becomes ovulatory, leaving the subordinate follicles to undergo atresia. These physiological processes are controlled by timely and spatially expressed genes and gene products, which in turn are regulated by post-transcriptional regulators. MicroRNAs, a class of short non-coding RNA molecules, are one of the important posttranscriptional regulators of genes associated with various cellular processes. Here we investigated the expression pattern of miRNAs in granulosa cells of bovine preovulatory dominant and subordinate follicles during the late follicular phase of bovine estrous cycle using Illumina miRNA deep sequencing. In addition to 11 putative novel miRNAs, a total of 315 and 323 known miRNAs were detected in preovulatory dominant and subordinate follicles, respectively. Moreover, in comparison with the subordinate follicles, a total of 64 miRNAs were found to be differentially expressed in preovulatory dominant follicles, of which 34 miRNAs including the miR-132 and miR-183 clusters were significantly enriched, and 30 miRNAs including the miR-17-92 cluster, bta-miR-409a and bta-miR-378 were significantly down regulated in preovulatory dominant follicles. In-silico pathway analysis revealed that canonical pathways related to oncogenesis, cell adhesion, cell proliferation, apoptosis and metabolism were significantly enriched by the predicted target genes of differentially expressed miRNAs. Furthermore, Luciferase reporter assay analysis showed that one of the differentially regulated miRNAs, the miR-183 cluster miRNAs, were validated to target the 3ยด-UTR of FOXO1 gene. Moreover FOXO1 was highly enriched in granulosa cells of subordinate follicles in comparison with the preovulatory dominant follicles demonstrating reciprocal expression pattern with miR-183 cluster miRNAs. In conclusion, the presence of distinct sets of miRNAs in granulosa cells of preovulatory dominant and subordinate follicles supports the potential role of miRNAs in post-transcriptional regulation of genes involved in bovine follicular development during the late follicular phase of the estrous cycle.//////////////////