METTL3 deficiency leads to ovarian insufficiency due to IL-1ß overexpression in theca cells.

Premature ovarian insufficiency (POI) is a clinical syndrome characterised by a decline in ovarian function in women before 40 years of age and is associated with oestradiol deficiency and a complex pathogenesis. However, the aetiology of POI is still unclear and effective preventative and treatment strategies are still lacking. Methyltransferase like 3 (METTL3) is an RNA methyltransferase that is involved in spermatogenesis, oocyte development and maturation, early embryonic development, and embryonic stem cell differentiation and formation, but its role in POI is unknown. In the present study, METTL3 deficiency in follicular theca cells was found to lead to reduced fertility in female mice, with a POI-like phenotype, and METTL3 knockout promoted ovarian inflammation. Further, a reduction in METTL3 in follicular theca cells led to a decrease in the m6A modification of pri-miR-21, which further reduced pri-miR-21 recognition and binding by DGCR8 proteins, leading to a decrease in the synthesis of mature miR-21-5p. Decrease of miR-21-5p promoted the secretion of interleukin-1ß (IL-1ß) from follicular theca cells. Acting in a paracrine manner, IL-1ß inhibited the cAMP-PKA pathway and activated the NF-κB pathway in follicular granulosa cells. This activation increased the levels of reactive oxygen species in granulosa cells, causing disturbances in the intracellular Ca2+ balance and mitochondrial damage. These cellular events ultimately led to granulosa cell apoptosis and a decrease in oestradiol synthesis, resulting in POI development. Collectively, these findings reveal how METTL3 deficiency promotes the expression and secretion of IL-1ß in theca cells, which regulates ovarian functions, and proposes a new theory for the development of POI disease.

Melatonin protects oogenesis from hypobaric hypoxia-induced fertility damage in mice.

Environmental hypoxia adversely affects reproductive health in humans and animals at high altitudes. Therefore, how to alleviate the follicle development disorder caused by hypoxia exposure and to improve the competence of fertility in plateau non-habituated female animals are important problems to be solved urgently. In this study, a hypobaric hypoxic chamber was used for 4 weeks to simulate hypoxic conditions in female mice, and the effects of hypoxia on follicle development, proliferation and apoptosis of granulosa cells, reactive oxygen species (ROS) levels in MII oocyte and 2-cell rate were evaluated. At the same time, the alleviating effect of melatonin on hypoxic exposure-induced oogenesis damage was evaluated by feeding appropriate amounts of melatonin daily under hypoxia for 4 weeks. The results showed that hypoxia exposure significantly increased the proportion of antral follicles in the ovary, the number of proliferation and apoptosis granulosa cells in the follicle, and the level of ROS in MII oocytes, eventually led to the decline of oocyte quality. However, these defects were alleviated when melatonin was fed under hypoxia conditions. Together, these findings suggest that hypoxia exposure impaired follicular development and reduced oocyte quality, and that melatonin supplementation alleviated the fertility reduction induced by hypoxia exposure.

Multi-omics analysis reveals gut microbiota-ovary axis contributed to the follicular development difference between Meishan and Landrace × Yorkshire sows.

BACKGROUND: The mechanism by which Meishan (MS) sows are superior to white crossbred sows in ovarian follicle development remains unclear. Given gut microbiota could regulate female ovarian function and reproductive capacity, this study aimed to determine the role of gut microbiota-ovary axis on follicular development in sows. METHODS: We compared the ovarian follicular development, gut microbiota, plasma metabolome, and follicular fluid metabolome between MS and Landrace × Yorkshire (L × Y) sows. A H2O2-induced cell apoptosis model was used to evaluate the effects of multi-omics identified metabolites on the apoptosis of porcine ovarian granulosa cells in vitro. RESULTS: Compared with L × Y sows, MS sows have greater ovary weight and improved follicular development, including the greater counts of large follicles of diameter ≥ 5 mm, secondary follicles, and antral follicles, but lesser atretic follicles. The ovarian granulosa cells in MS sows had alleviated apoptosis, which was indicated by the increased BCL-2, decreased caspases-3, and decreased cleaved caspases-3 than in L × Y sows. The ovarian follicular fluid of MS sows had higher concentrations of estradiol, progesterone, follicle-stimulating hormone, luteinizing hormone, and insulin like growth factor 1 than L × Y sows. Gut microbiota of MS sows formed a distinct cluster and had improved alpha diversity, including increased Shannon and decreased Simpson than those of L × Y sows. Corresponding to the enhanced function of carbohydrate metabolism and elevated short-chain fatty acids (SCFAs) in feces, the differential metabolites in plasma between MS and L × Y sows are also mainly enriched in pathways of fatty acid metabolism. There were significant correlations among SCFAs with follicular development, ovarian granulosa cells apoptosis, and follicular fluid hormones, respectively. Noteworthily, compared with L × Y sows, MS sows had higher follicular fluid SCFAs concentrations which could ameliorate H2O2-induced porcine granulosa cells apoptosis in vitro. CONCLUSION: MS sows have more secondary and antral follicles, but fewer atretic follicles and apoptotic ovarian granulosa cells, as well as harbored a distinctive gut microbiota than L × Y sows. Gut microbiota may participate in regulating ovarian follicular development via SCFAs affecting granulosa cells apoptosis in sows.

Large extracellular vesicles in bovine follicular fluid inhibit the apoptosis of granulosa cell and stimulate the production of steroid hormones.

The cargo carried by extracellular vesicles (EVs) plays an important physiological role in their corresponding target organs or target tissue cells. Extracellular vesicles are classified into large extracellular vesicles (LEVs) and small extracellular vesicles (SEVs) according to their diameters. Since different subtypes contain different contents, their roles are also different. In this study, the morphology and size of LEVs were analyzed by transmission electron microscopy and nanoparticle size, and the marker proteins of LEVs (CD63, GP96, TSG101, ALB) were identified by western blot, and high-purity LEVs were obtained. Through the uptake of extracellular vesicles by purified ovarian granulosa cells and the determination of granulosa cell viability, cell apoptosis, and steroid hormone production, the result indicated that LEVs significantly enhanced cell viability (P < 0.05), reduced the rate of granulosa cell apoptosis (P < 0.05). Meanwhile, LEVs promoted the secretion of estradiol in granulosa cells (P < 0.05). This study provides a reference for the in-depth study of the function of follicular fluid extracellular vesicle subtypes and the research on the regulation of extracellular vesicles on follicle and oocyte development.

New Anti-Müllerian Hormone Target Genes Involved in Granulosa Cell Survival in Women With Polycystic Ovary Syndrome.

PURPOSE: A protective effect of anti-Müllerian hormone (AMH) on follicle atresia was recently demonstrated using long-term treatments, but this effect has never been supported by mechanistic studies. This work aimed to gain an insight into the mechanism of action of AMH on follicle atresia and on how this could account for the increased follicle pool observed in women with polycystic ovary syndrome (PCOS). METHODS: In vivo and in vitro experiments were performed to study the effects of AMH on follicle atresia and on the proliferation and apoptosis of granulosa cells (GCs). RNA-sequencing was carried out to identify new AMH target genes in GCs. The expression of some of these genes in GCs from control and PCOS women was compared using microfluidic real time quantitative RT-PCR. RESULTS: A short-term AMH treatment prevented follicle atresia in prepubertal mice. Consistent with this result, AMH inhibited apoptosis and promoted proliferation of different models of GCs. Moreover, integrative biology analyses of 965 AMH target genes identified in 1 of these GC models, confirmed that AMH had initiated a gene expression program favoring cell survival and proliferation. Finally, on 43 genes selected among the most up- and down-regulated AMH targets, 8 were up-regulated in GCs isolated from PCOS women, of which 5 are involved in cell survival. MAIN CONCLUSIONS: Our results provide for the first time cellular and molecular evidence that AMH protects follicles from atresia by controlling GC survival and suggest that AMH could participate in the increased follicle pool of PCOS patients.

Granulosa cells apoptosis and follicular fluid hormones: comparison of progestin-primed ovarian stimulation versus GnRH antagonist protocols.

OBJECTIVE: To explore the effect of progestin-primed ovarian stimulation protocol (PPOS) on mural granulosa cells (GCs) apoptosis and hormonal profiles in follicular fluid (FF) and efficacy over GnRH antagonist (GnRH-A) protocols. METHODS: We performed a prospective cohort study from June through August 2017 at a tertiary teaching hospital. 63 Patients meeting our criteria were recruited in this prospective study voluntarily and stratified to PPOS or GnRH-A group randomly. Mural GCs and FF were collected during oocyte retrieval. Apoptosis of GCs was assessed using the Annexin V-affinity assay by flow cytometry and hormonal profiles in FF were measured using electrochemiluminescence. RESULTS: A total of 63 women were assessed for eligibility, with 25 cases in PPOS group and 38 in GnRH-A group. Difference of early stage apoptosis rate, late stage apoptosis rate, and total apoptosis rate did not reach statistical significance between groups. Meanwhile, concentrations of hormones in FF were comparable in two groups. No statistically significant differences were observed in number of oocytes retrieved, mature oocyte rate, fertilization rate, and top-quality embryos rate. No patients experienced premature LH surge in both groups during the study. CONCLUSION: Compared to GnRH antagonist protocol, PPOS had comparable laboratory outcomes, GCs apoptosis rate and hormonal profiles in FF. PPOS is an effective and safe alternative option to provide controlled ovarian hyperstimulation (COH).

Effect of Yiqixue Recipe on Ovary Apoptosis and Expression of Bim in Ovarian Granulosa Cells of Con-trolled Ovarian Hyperstimulation Rats / 实用医学杂志

Objective To assess the effects of Jinghou Zengzhi Recipe(JHZZR),a Chinese prescription with the action of tonifying Qi and blood ,on the ovary apoptosis and expression of Bim in ovarian granulosa cells (GCs) of controlled ovarian hyperstimulation(COH) rats , and analyze the possible therapeutic mechanism. Methods A model of COH rats were prepaered and 30 female SD rats were randomly divided into 5 groups , including control group,positive control group,low,medium and high concentration group in six rats in each group. The apoptosis index(AI)in ovarian GCs were detected by TUNEL ,and the expression of Bim by qPCR. Results The AI of ovarian GCs in high and medium concentration group were obviously lower(P 0.05)comparing with control group. The mRNA levels of Bim were lower(P0.05)during the three concentration groups in Bim mRNA. Conclusion JHZZR can inhibit the ovarian GCs apoptosis of COH rats through decreasing the expression of Bim mRNA ,which improve the quality of ovarian follicle.

Effect of yiqixue recipe on expressions of Bcl-2,Bax and Caspase3 in ovarian granulosa cells of controlled ovarian hyperstimulation mice / 实用医学杂志

Objective To assess the effects of Jinghou Zengzhi Recipe ,a Chinese prescription with the action of tonifying Qi and blood,on the expressions of Bcl-2,Bax and Caspase3 in ovarian granulosa cells of con-trolled ovarian hyperstimulation(COH)mice. Methods A model of COH mice was prepared and 30 female KM mice were divided into blank group,model group and treatment group. The expressions of Bcl-2,Bax and Cas-pase3 were detected by Real-time Quantitative PCR and Western Blot. Results The mRNA and protein levels of Bax and Caspase3 were lower(P<0.05),while the protein levels of Bcl-2 were significantly higher(P<0.05)in the treatment group than those in the model group. There was no significant differences between the treatment group and blank group in the mRNA and proteins. Conclusion Jinghou Zengzhi Recipe can inhibit the ovarian granulo-sa cellular apoptosis of COH mice through increasing the expression of Bcl-2 protein as well as decreasing the ex-pressions of Bax and Caspase3 mRNA and proteins to nearly the natural level,which improves the quality of ovari-an follicle.