miR-21 is involved in norepinephrine-mediated rat granulosa cell apoptosis by targeting SMAD7

Psychological stressors involved in the pathogenesis of premature ovarian insufficiency and potential intervention measures

Premature ovarian insufficiency (POI) is a common gynecological endocrine disease, which seriously affects women's physical and mental health and fertility, and its incidence is increasing year by year. With the development of social economy and technology, psychological stressors such as anxiety and depression caused by social, life and environmental factors may be one of the risk factors for POI. We used PubMed to search peer-reviewed original English manuscripts published over the last 10 years to identify established and experimental studies on the relationship between various types of stress and decreased ovarian function. Oxidative stress, follicular atresia, and excessive activation of oocytes, caused by Stress-associated factors may be the main causes of ovarian function damage. This article reviews the relationship between psychological stressors and hypoovarian function and the possible early intervention measures in order to provide new ideas for future clinical treatment and intervention.

Acupuncture regulates the apoptosis of ovarian granulosa cells in polycystic ovarian syndrome-related abnormal follicular development through LncMEG3-mediated inhibition of miR-21-3p

BACKGROUND

The main features of polycystic ovary syndrome (PCOS) are abnormal follicular development and ovulatory dysfunction, which are caused by excessive apoptosis of ovarian granulosa cells. Acupuncture has been shown to improve follicular development abnormalities in patients with PCOS, but its mechanism is unknown. This study hypothesized that the mechanism of acupuncture on follicular development abnormalities in PCOS patients is the inhibition of granulosa cell apoptosis through LncMEG3-mediated regulation of miR-21-3p.

METHODS

A PCOS-like rat model was established using subcutaneous injection of dehydroepiandrosterone (DHEA). Acupuncture was performed on rats for 15 d (CV-4, RN-3, CV-6, SP-6 and EX-CA 1). Ovarian morphology was observed by HE staining, and sex hormone and AMH levels were detected by ELISA. Primary granulosa cells were isolated from each group of rats to assess the association of acupuncture treatment, LncMEG3, miR-21-3p, and granulosa cell apoptosis in rats with PCOS.

RESULTS

LncMEG3 and miR-21-3p were highly expressed in the ovarian granulosa cells of rats with PCOS, and LncMEG3-mediated regulation of miR-21-3p was involved in the development of PCOS in rats. Silencing of MEG3 attenuated sex hormone dysregulation and ovarian histopathological changes in PCOS rats and promoted follicle cell development and maturation. In addition, silencing MEG3 increased the viability and number of granulosa cells. In addition, silencing MEG3 further inhibited early and late apoptosis of ovarian granulosa cells in PCOS rats. Acupuncture improved polycystic ovarian morphology and sex hormone levels in PCOS rats. Acupuncture intervention increased the viability and number of granulosa cells. Acupuncture intervention inhibited early and late apoptosis of ovarian granulosa cells in PCOS rats by targeting miR-21-3p via LncMEG3.

CONCLUSION

These results suggest that acupuncture can downregulate LncMEG3, thereby targeting and regulating miR-21-3p to suppress early and late granulosa cell apoptosis and normalize their proliferation. These factors ultimately compensate for abnormal follicular development. These findings shed light on the clinical potential of acupuncture as a safe treatment for follicular developmental abnormalities in PCOS.

Granulosa cells undergo BPA-induced apoptosis in a miR-21-independent manner

Bisphenol A (BPA) is a harmful endocrine disrupting compound that alters not only classical cellular mechanisms but also epigenetic mechanisms. Evidence suggests that BPA-induced changes in microRNA expression can explain, in part, the changes observed at both the molecular and cellular levels. BPA is toxic to granulosa cells (GCs) as it can activate apoptosis, which is known to contribute to increased follicular atresia. miR-21 is a crucial antiapoptotic regulator in GCs, yet the exact function in a BPA toxicity model remains unclear. BPA was found to induce bovine GC apoptosis through the activation of several intrinsic factors. BPA reduced live cells counts, increased late apoptosis/necrosis, increased apoptotic transcripts (BAX, BAD, BCL-2, CASP-9, HSP70), increased the BAX/Bcl-2 ratio and HSP70 at the protein level, and induced caspase-9 activity at 12 h post-exposure. miR-21 inhibition increased early apoptosis and, while it did not influence transcript levels or caspase-9 activity, it did elevate the BAX/Bcl-2 protein ratio and HSP70 in the same manner as BPA. Overall, this study shows that miR-21 plays a molecular role in regulating intrinsic mitochondrial apoptosis; however, miR-21 inhibition did not make the cells more sensitive to BPA. Therefore, apoptosis induced by BPA in bovine GCs is miR-21 independent.

Deregulated RNAs involved in sympathetic regulation of sepsis-induced acute lung injury based on whole transcriptome sequencing

Sympathetic nerves play essential roles in the regulation of lung inflammation, and we investigated the effect of sympathetic denervation (SD) on sepsis-induced acute lung injury (ALI) in mice. Mice were randomized to the control, SD, ALI and SD + ALI, groups. SD and ALI were established through intratracheal 6-hydroxydopamine and intraperitoneal lipopolysaccharide, respectively. Models and gene expressions levels were evaluated by HE staining, ELISA, Western blotting and RT-qPCR. RNA extraction, whole transcriptome sequencing and subsequent biostatistical analysis were performed. Sympathetic denervation in the lungs significantly attenuated lung TNF-ɑ and norepinephrine expression, alleviated sepsis-induced acute lung injury and inhibited NF-κB signaling. Compared with the ALI group, the SD + ALI group exhibited 629 DE circRNAs, 269 DE lncRNAs,7 DE miRNAs and 186 DE mRNAs, respectively. Some DE RNAs were validated by RT-qPCR. CircRNA-miRNA-mRNA regulatory networks in the SD + ALI group revealed enrichment of the B-cell receptor signaling pathway, IL-17 signaling pathway, neuroactive ligand-receptor interaction, CAM, primary immunodeficiency, and cytokine-cytokine receptor interaction terms. The lncRNA-miRNA-mRNA network also revealed inflammation-related signaling pathways. Taken together, based on the successfully established models of SD and ALI, we show here that sympathetic nerves may regulate sepsis-induced ALI supposedly by affecting the expression of circRNAs, lncRNAs, miRNAs, and mRNAs in the lungs. These results may allow for further exploration of the roles of pulmonary sympathetic nerves in sepsis-induced ALI.

Identification of differentially expressed microRNAs in ovulatory and subordinate follicles in Dazu black goats

How multiple ovulations happen in prolific goats is still unknown even though studies on ovarian physiology and folliculogenesis have made extensive progress. MicroRNAs (miRNAs) are a class of endogenous regulatory factors and regulate structural gene expression mainly at the post-transcriptional level. In this study, in the follicular phase, six large follicles were collected from prolific Dazu black goat and used to generate RNA libraries for RNA sequencing. Based on the litter size and average number of ovulatory follicles in Dazu black goats, the largest three follicles were sorted as ovulatory follicles, and the remaining as subordinate ones. In total, 418 known miRNAs and 110 novel miRNAs were found, and the expression of six randomly selected miRNAs was validated by quantitative PCR analysis. Nine miRNAs were differently expressed between the ovulatory and subordinate follicles (p < 0.01). Chi-miR-582-5p, novel-130, chi-miR-214-3p, and chi-miR-500-5p were upregulated in the ovulatory group, and chi-miR-383, chi-miR-130b-5p, chi-miR-92a-3p, chi-miR-125b-5p, and novel-9 were downregulated in the same group. Chi-miR-130b-5p and chi-miR-214-3p were predicted to target at LHR (XM_013967581.1), GDF9 (NM_001285708.1), BMP15 (NM_001285588.1), and CYP19A1 (XM_013967046.1). In conclusion, nine miRNAs were differently expressed between ovulatory and subordinate follicles, and chi-miR-130b-5p and chi-miR-214-3p were predicted to regulate the expression of genes involved in gonadotropin hormone signaling and oocyte-derived growth factors. Additional studies are needed to confirm these findings.

Interplay between nitric oxide and gonadotrophin-releasing hormone in the neuromodulation of the corpus luteum during late pregnancy in the rat

BACKGROUND

Nitric oxide and GnRH are biological factors that participate in the regulation of reproductive functions. To our knowledge, there are no studies that link NO and GnRH in the sympathetic ganglia. Thus, the aim of the present work was to investigate the influence of NO on GnRH release from the coeliac ganglion and its effect on luteal regression at the end of pregnancy in the rat.

METHODS

The ex vivo system composed by the coeliac ganglion, the superior ovarian nerve, and the ovary of rats on day 21 of pregnancy was incubated for 180 min with the addition, into the ganglionic compartment, of L-NG-nitro arginine methyl ester (L-NAME), a non-selective NO synthase inhibitor. The control group consisted in untreated organ systems.

RESULTS

The addition of L-NAME in the coeliac ganglion compartment decreased NO as well as GnRH release from the coeliac ganglion. In the ovarian compartment, and with respect to the control group, we observed a reduced release of GnRH, NO, and noradrenaline, but an increased production of progesterone, estradiol, and expression of their limiting biosynthetic enzymes, 3β-HSD and P450 aromatase, respectively. The inhibition of NO production by L-NAME in the coeliac ganglion compartment also reduced luteal apoptosis, lipid peroxidation, and nitrotyrosine, whereas it increased the total antioxidant capacity within the corpora lutea.

CONCLUSION

Collectively, the results indicate that NO production by the coeliac ganglion modulates the physiology of the ovary and luteal regression during late pregnancy in rats.

miR-21, miR-125b, and let-7b contribute to the involution of atretic follicles and corpus lutea in Tibetan sheep ovaries

Follicular granulosa cells (FGCs) are crucial for ovarian follicle functions, and miRNAs are differentially expressed at various stages of follicular developments. In this study, we confirmed that miR-21, miR-125b, and let-7b were located in FGCs/luteal cells by in situ hybridization experiments. Moreover, miR-21 and miR-125b expressions were upregulated in late corpus lutea (CL) and atretic follicles (AF); let-7b expression was increased in early AF. After transfected with inhibitor or mimic of miRNAs in FGCs, we found that FGCs apoptosis was decreased in the miR-21-mi group but increased in the miR-125b-mi group using flow cytometry. mRNA and protein expression levels were determined for apoptosis-related factors (e.g., Bcl-2 and Bax), the potential target genes of miRNAs (e.g., SMAD7, SP1, and STAT3), hormone receptors (e.g., FSHR and LHR), and genes related to hormone secretion (e.g., CYP19, CYP11, and 3βHSD). The protein levels of SMAD7 were decreased in the miR-21-mi group but opposite to SP1 and FSHR. In the let-7b-mi group, Bcl-2, SMAD7, and FSHR were suppressed but not Bax, CYP11, and 3βHSD. However, hormone secretion was not changed in the supernatant of transfected FGCs. This study provides information about ovarian miRNAs to improve the fertility in Tibetan sheep.

rno-miR-128-3p promotes apoptosis in rat granulosa cells (GCs) induced by norepinephrine through Wilms tumor 1 (WT1)

The mechanism related to ovarian follicular is complex, which has not been fully elucidated. Abundant reports have confirmed that the ovarian function development is closely related to sympathetic innervation. As one of the major neurotransmitters, norepinephrine (NE) is considered an effective regulator of ovarian functions like granulosa cell (GC) apoptosis. However, the mechanism between NE and GC apoptosis in rat is still unclear. In our study, GCs were isolated and cultured in vitro with NE treatment. The apoptosis of GCs was facilitated by NE. Wilms tumor 1 (WT1) was found to be significantly downregulated in GCs after NE treatment, and overexpression of WT1 repressed apoptosis in rat GCs induced by NE. rno-miR-128-3p was found to be significantly enhanced by NE in GCs, and inhibition of rno-miR-128-3p repressed apoptosis in rat GCs induced by NE. Mechanistically, rno-miR-128-3p interacted with WT1 and repressed its expression. In summary, inhibition of rno-miR-128-3p may enhance WT1 expression, and then repress NE-induced apoptosis in rat GCs. Our research may provide a new insight for the improvement of ovarian follicular development.

Extracellular vesicles of bovine small follicular fluid promote ovarian cortical stromal cell proliferation and steroidogenesis

The aim of this study was to investigate the effects of extracellular vesicles (EVs) on the proliferation and steroid hormone synthesis of bovine ovarian cortical stromal cells in vitro. The release and uptake of EVs are the new mechanisms of cell-to-cell communication. Using reverse transcriptase polymerase chain reaction, enzyme-linked immunosorbent assay, TUNEL and other experiments, we found that EVs in bovine follicular fluid can promote the proliferation and synthesis of androstenedione and progesterone in ovarian cortical stromal cells. Moreover, 100 μg/ml EVs caused the most significant effect. We conclude that EVs at 100 μg/ml can significantly promote the proliferation and synthesis of androstenedione and progesterone in ovarian cortical stromal cells. This research is of great significance for further elucidating the regulatory role of follicular fluid EVs in follicular development and atresia and for research on the interaction of ovarian stromal cells, granulosa cells and oocytes.

The role of microRNAs in ovarian function and the transition toward novel therapeutic strategies in fertility preservation: from bench to future clinical application

BACKGROUND

New therapeutic approaches in oncology have converted cancer from a certain death sentence to a chronic disease. However, there are still challenges to be overcome regarding the off-target toxicity of many of these treatments. Oncological therapies can lead to future infertility in women. Given this negative impact on long-term quality of life, fertility preservation is highly recommended. While gamete and ovarian tissue cryopreservation are the usual methods offered, new pharmacological-based options aiming to reduce ovarian damage during oncological treatment are very attractive. In this vein, advances in the field of transcriptomics and epigenomics have brought small noncoding RNAs, called microRNAs (miRNAs), into the spotlight in oncology. MicroRNAs also play a key role in follicle development as regulators of follicular growth, atresia and steroidogenesis. They are also involved in DNA damage repair responses and they can themselves be modulated during chemotherapy. For these reasons, miRNAs may be an interesting target to develop new protective therapies during oncological treatment. This review summarizes the physiological role of miRNAs in reproduction. Considering recently developed strategies based on miRNA therapy in oncology, we highlight their potential interest as a target in fertility preservation and propose future strategies to make the transition from bench to clinic.

OBJECTIVE AND RATIONALE

How can miRNA therapeutic approaches be used to develop new adjuvant protective therapies to reduce the ovarian damage caused by cytotoxic oncological treatments?

SEARCH METHODS

A systematic search of English language literature using PubMed and Google Scholar databases was performed through to 2019 describing the role of miRNAs in the ovary and their use for diagnosis and targeted therapy in oncology. Personal data illustrate miRNA therapeutic strategies to target the gonads and reduce chemotherapy-induced follicular damage.

OUTCOMES

This review outlines the importance of miRNAs as gene regulators and emphasizes the fact that insights in oncology can inspire new adjuvant strategies in the field of onco-fertility. Recent improvements in nanotechnology offer the opportunity for drug development using next-generation miRNA-nanocarriers.

WIDER IMPLICATIONS

Although there are still some barriers regarding the immunogenicity and toxicity of these treatments and there is still room for improvement concerning the specific delivery of miRNAs into the ovaries, we believe that, in the future, miRNAs can be developed as powerful and non-invasive tools for fertility preservation.

MiR-21-5p actions at the Smad7 gene during pig ovarian granulosa cell apoptosis

MicroRNAs (miRNAs) are endogenous non-coding RNAs in eukaryotic cells that modulate apoptosis of ovarian granulosa cells (GCs), which is an important cause of mammalian follicular atresia. In the present study, associations were evaluated between miR-21-5p and the extent of Smad7 protein production in regulation of ovarian granulosa cell (pGC) apoptosis. There was detection of miR-21-5p and Smad7 primarily in the cytoplasm and nucleus of pGCs, respectively. When there was an enhanced abundance of miR-21-5p and decreased abundance of Smad7 there were similar effects in pGCs, including inducing proliferation, inhibiting apoptosis, increasing the number of cells in S and G2/M phases, increasing serum estradiol, and decreasing serum progesterone concentrations. Furthermore, the Smad7 mRNA transcript was identified as a target for miR-21-5p actions, with enhanced abundances of miR-21-5p being associated with a lesser abundance of Smad7 mRNA transcript and protein in pGCs. Overall, results from the present study indicate that miR-21-5p has actions on the Smad7 mRNA transcript during the process of ovarian granulosa cell apoptosis in pigs.

Chronic stress promotes EMT-mediated metastasis through activation of STAT3 signaling pathway by miR-337-3p in breast cancer

Chronic stress could induce cancer metastasis by constant activation of the sympathetic nervous system, while cellular mechanism remains obscure. The aim of this research is to explore the metastasis associated negative effect of chronic stress. The analysis of transcriptome sequencing implied that activation of STAT3 signaling pathway by downregulated miR-337-3p might be a potential mechanism to induce epithelial to mesenchymal transition (EMT) of cancer cell and promote metastasis under chronic stress. We also verified this biological process in further experiments. Downregulation of miR-337-3p could downregulate E-cadherin expression and upregulate vimentin expression in vitro and in vivo. STAT3, related signal pathways of which are involved in metastasis regulation, was directly targeted by miR-337-3p. In conclusion, the above results denoted that activation of miR-337-3p/STAT3 axis might be a potential pathway for the increasing metastasis of breast cancer under chronic stress.

Ganglionic and ovarian action of acetylcholine during diestrous II in rats. Neuroendocrine control of the luteal regression

Our aim was to investigate if acetylcholine (Ach), added to the celiac ganglion-superior ovarian nerve-ovary system (CG-SON-ovary) or in ovary incubations, modifies the release of progesterone (P₄), androstenedione (A₂), dopamine (DA), norepinephrine (NE), gonadotropin-releasing hormone (GnRH), and alters the expression of 3β-hydroxysteroid dehydrogenase (3β-HSD), 20α-hydroxysteroid dehydrogenase (20α-HSD), and apoptotic genes in ovarian tissue during the diestrous II (DII) in rats. The CG-SON-ovary system or the ovary alone were removed and placed into separate cuvettes both containing Krebs-Ringer solution (control groups). In experimental groups, 10^-6 M Ach was added into the ganglion compartment or into the ovary compartment. P₄, A₂ and GnRH were measured by RIA, mRNA expression by RT-PCR, and catecholamines by HPLC. In addition, a routine histological technique was applied. In ex-vivo system, 10^-6 M Ach into the ganglion compartment decreased P₄ and NE release, altered 3β-HSD and 20α-HSD expression, and decreased bax/bcl-2 ratio, while increasing the release of A₂ and DA, and bcl-2 expression. In ovary incubations, 10^-6 M Ach decreased P₄ and GnRH release, decreased 3β-HSD and bcl-2 expression, increased A₂ release, increased 20α-HSD and bax expression, and the bax/bcl-2 ratio, and induced disorganization of the corpus luteum structure. The peripheral nervous system protected the ovary from the apoptotic mechanisms while in the ovary incubation the effect was reversed. Our results indicate that Ach in DII regulates steroidogenesis and apoptosis in the ovary, by modulating the concentration of neurotransmitters. In vivo, an alteration in the extrinsic cholinergic innervation of the ovary could disrupt the endocrine control of the reproductive function.

The feedback loop between miR-21, PDCD4 and AP-1 functions as a driving force for renal fibrogenesis

Renal fibrosis is a final common pathway of chronic kidney disease. Sustained activation of fibroblasts is considered to play a key role in perpetuating renal fibrosis but the driving force in the perpetuation stage is only partially understood. To date, some investigations have specifically identified overexpression of microRNA 21 (miR-21) in the progression of kidney fibrosis. Nevertheless, the precise role of miR-21 in fibroblast activation remains largely unknown. In this study, we found that miR-21 was significantly upregulated in activated fibroblasts and that it maintained itself at constant high levels by employing an auto-regulatory loop between miR-21, PDCD4 and AP-1. Persistently upregulated miR-21 suppressed protein expression of Smad7 and, eventually, enhanced the TGF-β1/Smad pathway to promote fibroblast activation. More importantly, we found miR-21 sequestration with miR-21 antagomir or AP-1 inhibitors attenuated unilateral ureteral obstruction (UUO)-induced renal fibrosis. miR-21-knockout mice also suffered far less interstitial fibrosis in response to kidney injury. Altogether, these data suggest that miR-21 is a main driving force of fibroblast activation and keeps its high expression level by employing a double negative autoregulatory loop. Targeting this aberrantly activated feedback loop may provide new therapeutic strategy in treating fibrotic kidneys.

miR-181b-induced SMAD7 downregulation controls granulosa cell apoptosis through TGF-β signaling by interacting with the TGFBR1 promoter

SMAD7 disrupts the TGF-β signaling pathway by influencing TGFBR1 stability and by blocking the binding of TGFBR1 to SMAD2/3. In this study, we showed that SMAD7 attenuated the TGF-β signaling pathway in ovarian granulosa cells (GCs) by regulating TGFBR1 transcriptional activity. To function as a transcription factor, SMAD7 downregulated the mRNA levels of TGFBR1 via direct binding to the SMAD-binding elements (SBEs) within the promoter region of pig TGFBR1. We also showed that SMAD7 enhanced porcine GC apoptosis by interrupting TGFBR1 and the TGF-β signaling pathway. Interestingly, miR-181b, a microRNA that is downregulated during porcine follicular atresia, was identified to be directly targeting SMAD7 at its 3'-UTR. By inhibiting SMAD7, miR-181b could inhibit GC apoptosis by activating the TGF-β signaling pathway. Our findings provide new insights into the mechanisms underlying the regulation of the TGF-β signaling pathway by SMAD7 and miR-181b.