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]
Induction of miR-15a expression by tripterygium glycosides caused premature ovarian failure by suppressing the Hippo-YAP/TAZ signaling effector Lats1. Ai A et al. (2018) Tripterygium glycosides (TGs) are chemotherapeutic drugs and immunosuppressant agents for the treatment of cancer and autoimmune diseases. We have previously reported that TGs induces premature ovarian failure (POF) by inducing cytotoxicity in ovarian granulosa cells (OGCs). Hence, we report that TGs suppress the expression of the Hippo-YAP/TAZ pathway in murine OGCs in vitro and in vivo. We found that the expressions of miR-181b, miR-15a, and miR-30d, were elevated significantly in the POF. Luciferase reporter assays confirmed that miR-15a targets Lats1 through a miR-15a binding site in the Lats1 3'UTR. Overexpression of miR-15a in mOGCs not only inhibited proliferation and growth of mOGCs, but also induced aging of mOGCs. Western blot and qPCR analysis indicated that miR-15a suppresses the expression of the Hippo-YAP/TAZ pathway in mOGCs. When the exogenous miR-15a was expressed on mouse OGCs, it could elevate the cytotoxicity effect of TG on mOGCs. We conclude that tripterygium glycosides promote cytotoxicity, senescence, and apoptosis in ovarian granulosa cells by inducing endogenous miR-15a expression and inhibiting the Hippo-YAP/TAZ pathway.//////////////////
Involvement of MicroRNA Mir15a in Control of Human Ovarian Granulosa Cell Proliferation, Apoptosis, Steroidogenesis, and Response to FSH. Sirotkin AV 2014 et al.
Our study aimed to examine the role of micro RNA Mir15a in control of basic ovarian cell functions: proliferation, apoptosis, and secretory activity. In the first series of experiments, primary human ovarian granulosa cells were transfected with antisense construct blocking Mir15a (anti-Mir15a) and cultured without hormonal treatments. Accumulation of markers of proliferation (MAPK/ERK1,2 and PCNA) and apoptosis (caspase 3 and bax), and release of steroid hormones (progesterone, testosterone, and estradiol) were evaluated by immunocytochemical analysis and by enzyme immunoassay. In the second series of experiments, granulosa cells were transfected with gene construct encoding Mir15a precursor (pre-Mir15a) and cultured with and without follicle-stimulating hormone (FSH; 0, 1, 10, and 100 ng/ml). Expression of markers of proliferation (MAPK/ERK1,2) apoptosis (caspase 3), and steroidogenesis (release of progesterone, testosterone, and estradiol) were evaluated. Transfection of cells with anti-Mir15a resulted in a significant increase in accumulation of both proliferation and apoptosis markers, a reduction in progesterone and testosterone release, and an increase in estradiol release. Transfection of cells with pre-Mir15a had an opposite effect: it reduced accumulation of proliferation- and apoptosis-related proteins MAPK/ERK1,2 and caspase 3, and promoted release of progesterone and testosterone, but not estradiol. Moreover, pre-Mir15a reversed the effect of FSH on caspase 3, progesterone, and testosterone, but not on MAPK/ERK1,2 and estradiol. Our observations demonstrate involvement of Mir15a in control of multiple ovarian functions: proliferation, apoptosis, release of progesterone, androgen, and estrogen, and response to gonadotropin. Moreover, this is the first demonstration that miRNAs can affect response of cells to hormonal regulators. We propose that Mir15 could potentially be used for control of different reproductive processes.
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Expression regulated by
Comment
Ovarian localization
Oocyte, Granulosa, Follicular Fluid
Comment
miR-15a-5p levels correlate with poor ovarian response in human follicular fluid. Zhang K et al. (2017) Poor ovarian response is a significant problem encountered during in vitro fertilization and embryo transfer procedures. Many infertile women may suffer from poor ovarian response and its incidence tends to be increasing in young patients nowadays. It is a major cause of maternal infertility because it is associated with low pregnancy and live birth rates. However, the cause of poor ovarian response is not clear. In this study, we extracted microRNAs from human follicular fluid and performed miRNA sequencing to investigate a potential posttranscriptional mechanism underlying poor ovarian response. The results showed that many miRNAs were obviously different between the poor ovarian response and non-poor ovarian response groups. We then performed quantitative Polymerase Chain Reaction, Western blot analysis and used an in vitro culture system to verify the sequencing results and to study the mechanism. Notably, we found that miRNA-15a-5p was significantly elevated in the young poor ovarian response group. Furthermore, we demonstrated that high levels of miR-15a-5p in the young poor ovarian response group repressed granulosa cell proliferation by regulating the PI3K-AKT-mTOR signaling pathway and promoted apoptosis through BCL2 and BAD. This could explain the reduced oocyte retrieval number seen in poor ovarian response patients.//////////////////
Identification of MicroRNAs controlling human ovarian cell proliferation and apoptosis. Sirotkin AV et al. Previous studies have shown that microRNAs (miRNAs) can control steroidogenesis in cultured granulosa cells. In this study we wanted to determine if miRNAs can also affect proliferation and apoptosis in human ovarian cells. The effect of transfection of cultured primary ovarian granulosa cells with 80 different constructs encoding human pre-miRNAs on the expression of the proliferation marker, PCNA, and the apoptosis marker, Bax was evaluated by immunocytochemistry. Eleven out of 80 tested miRNA constructs resulted in stimulation, and 53 miRNAs inhibited expression of PCNA. Furthermore, 11 of the 80 miRNAs tested promoted accumulation of Bax, while 46 miRNAs caused a reduction in Bax in human ovarian cells. In addition, two selected antisense constructs that block the corresponding miRNAs mir-15a and mir-188 were evaluated for their effects on expression of PCNA. An antisense construct inhibiting mir-15a (which precursor suppressed PCNA) increased PCNA, whereas an antisense construct for mir-188 (which precursor did not change PCNA) did not affect PCNA expression. Verification of effects of selected pre-mir-10a, mir-105, and mir-182 by using other markers of proliferation (cyclin B1) and apoptosis (TdT and caspase 3) confirmed specificity of miRNAs effects on these processes. This is the first direct demonstration of the involvement of miRNAs in controlling both proliferation and apoptosis by ovarian granulose cells, as well as the identification of miRNAs promoting and suppressing these processes utilizing a genome-wide miRNA screen. J. Cell. Physiol. (c) 2009 Wiley-Liss, Inc.
Differentially expressed micoRNAs in human oocytes. Xu YW et al. PURPOSE: To identify differentially expressed microRNAs (miRNAs) and expression patterns of specific miRNAs during meiosis in human oocytes. MATERIALS AND METHODS: To identify differentially expressed miRNAs, GV oocytes and MII oocytes matured at conventional FSH levels (5.5?ng/ml) were analyzed by miRNA microarray. Real-time RT-PCR was used to confirm the changed miRNAs. To validate the dynamic changes of miRNAs from GV to MII stages, oocytes were divided into four groups (#1-4), corresponding to GV oocytes, MI oocytes, MII oocytes matured in conventional FSH level and MII oocytes matured in high FSH level (2,000?ng/ml) respectively. RESULTS: Compared with GV oocytes, MII oocytes exhibited up-regulation of 4 miRNAs (hsa-miR-193a-5p, hsa-miR-297, hsa-miR-625 and hsa-miR-602), and down-regulation of 11 miRNAs (hsa-miR-888*, hsa-miR-212, hsa-miR-662, hsa-miR-299-5p, hsa-miR-339-5p, hsa-miR-20a, hsa-miR-486-5p, hsa-miR-141*, hsa-miR-768-5p, hsa-miR-376a and hsa-miR-15a). RT-PCR analysis of hsa-miR-15a and hsa-miR-20a expression revealed concordant dynamic changes in oocytes from group 1 to group 4. CONCLUSION(S): Specific miRNAs in human oocytes had dynamic changes during meiosis. High-concentration FSH in IVM medium led to reverse effect on the expression of hsa-miR-15a and hsa-miR-20a.