MicroRNA let-7g regulates mouse granulosa cell autophagy by targeting insulin-like growth factor 1 receptor

Umbilical cord mesenchymal stem cell-derived extracellular vesicles improve excessive autophagy of granulosa cells through METTL3

Polycystic ovary syndrome (PCOS) is a prevalent endocrine disorder impacting women's fertility. We assessed the effect of umbilical cord mesenchymal stem cell-derived extracellular vesicles (UC-MSC-EVs) on PTEN-induced kinase 1 (PINK1)/Parkin-mediated excessive autophagy of ovarian granulosa cells (GCs) through methyltransferase-like 3 (METTL3). Human ovarian GC line KGN was cultured and treated with dehydroepiandrosterone (DHEA) and UC-MSC-EVs. Cell apoptosis and viability, autophagy-related protein levels, adenosine triphosphate (ATP) and mitochondrial membrane potential (MMP) level, and microtubule-associated protein 1 light chain 3 β (LC3B) and translocase of outer mitochondrial membrane 20 (TOMM20) colocalization were assessed by flow cytometry, CCK-8, Western blot, kit, and immunofluorescence. PINK1 N6-methyladenosine (m6A) modification, METTL3 levels, and PINK1 mRNA stability were determined by methylated RNA immunoprecipitation, reverse transcription quantitative polymerase chain reaction, and Western blot. The PCOS mouse model was established and treated with UC-MSC-EVs. Serum hormone and ovarian tissue autophagy-related protein levels were determined by enzyme-linked immunosorbent assay. DHEA decreased KGN cell viability and p62 level, increased PINK1, Parkin, LC3BII/I, and Beclin-1 protein levels, ATP content, MMP level, TOMM20+LC3B+ cell number, and apoptosis, which were partly abrogated by UC-MSC-EV treatment. PINK1 had m6A modification sites. METTL3 was a PINK1 m6A-modified writer protein. After DHEA treatment, KGN cells showed elevated METTL3 and PINK1 m6A modification levels and mRNA stability, whereas UC-MSC-EV treatment caused the opposite results. METTL3 overexpression partly averted UC-MSC-EVs-improved PINK1/Parkin-mediated mitophagy. UC-MSC-EVs curbed PINK1/Parkin-mediated excessive autophagy through METTL3 and improved ovarian function in PCOS mice. In conclusion, UC-MSC-EVs suppressed PINK1/Parkin-mediated mitophagy of ovarian GCs through METTL3, thereby improving PCOS.NEW & NOTEWORTHY Polycystic ovary syndrome (PCOS) is a prevalent endocrine disorder impacting women's fertility. The authors in this study using DHEA-induced granulosa cells (GCs) demonstrated that umbilical cord mesenchymal stem cell-derived extracellular vesicles (UC-MSC-EVs) suppressed PINK1/Parkin-mediated mitophagy of ovarian GCs through METTL3, thereby improving PCOS.

Cathepsin B Regulates Ovarian Reserve Quality and Quantity via Mitophagy by Modulating IGF1R Turnover

The quality and quantity of the ovarian reserve are meticulously regulated through various cell death pathways to guarantee the availability of high-quality oocytes for fertilization. While apoptosis is recognized for contributing to maintaining ovarian reserve, the involvement of other cell death pathways remains unclear. Employing chemical genetics and proteomics, this study reveals the crucial involvement of Cathepsin B in maintaining the ovarian reserve. Results indicate that apoptosis and autophagy play pivotal roles, and inhibiting these pathways significantly increases follicle numbers. Proteomics reveals a dynamic shift from apoptosis to autophagy during follicular development, with Cathepsin B emerging as a key player in this transition. Inhibiting Cathepsin B not only mimics the augmented oocyte reserve observed with autophagy inhibition but also upregulated IGF1R and AKT-mTOR pathways without compromising fertility in pre- and postpubertal mice. Further, IGF1R inhibition partially compromised the protective effects of Cathepsin B inhibition on oocyte reserves, suggesting their interdependence. This association is further supported by the finding that Cathepsin B can degrade IGF1R in vitro. Moreover, the increased IGF1R levels enhance the oocyte mitochondrial membrane potential via transcriptional regulation of mitochondrial biogenesis and mitophagy genes. Remarkably, this Cathepsin B-dependent ovarian reserve maintenance mechanism is conserved in higher-order vertebrates. Cumulatively, our study sheds valuable light on the intricate interplay of autophagy, Cathepsin B, and growth factors in ovarian reserve maintenance, offering potential therapeutic strategies to delay ovarian aging and preserve fertility.

Discovery of differentially expressed lncRNAs in porcine ovaries with smaller and bigger litter size

Introduction

The number of litters is an important reproductive trait, which is one of the main indicators reflecting the production level and economic benefit of the pig farm. As an important reproductive organ of female mammals, the ovary is controlled by a complex transcription network of coding and non-coding genes to undergo a series of biological processes during each estrus cycle, thereby regulating the reproductive capacity of the sow. However, these molecular regulation mechanisms affecting sow litter size are still unclear.

Methods

Regarding the non-coding molecular regulatory mechanisms in ovarian function with smaller and larger litter size (SLS and LLS), we investigated the expression profile of lncRNA in pig SLS and LLS samples. Total RNAs from porcine ovaries were used to construct libraries using Ribo-Zero RNA sequencing method.

Results

Here we profiled the expression of lncRNA in porcine ovaries with SLS and LLS, and identified a total of 3,556 lncRNA candidates, of which 96 were upregulated lncRNA and 206 were downregulated lncRNA when comparing LLS to SLS. In addition, a competitive endogenous RNA (ceRNA) network was constructed, and it was found that lncRNAs LOC100513133 and LOC102168075 may serve as ceRNAs containing potential binding sites for miR-26b, let-7g and miR-125b.

Discussion

These results demonstrate that lncRNAs may play roles in modulating porcine litter size.

Upregulated let-7 expression in the follicular fluid of patients with endometriomas leads to dysfunction of granulosa cells through targeting of IGF1R

STUDY QUESTION

What molecular mechanisms underlie the decline in ovarian reserve as the number and quality of oocytes decrease in patients with ovarian endometriomas (OEM)?

SUMMARY ANSWER

Elevated expression of the let-7 micro(mi)RNAs in the follicular microenvironment of OEM-affected ovaries targets the expression of type 1 insulin-like growth factor receptor (IGF1R) in granulosa cell (GC) and disrupts their proliferation, steroid hormone secretion levels, adenosine triphosphate (ATP) energy metabolism, and reactive oxygen species (ROS) oxidative stress levels.

WHAT IS KNOWN ALREADY

Patients with OEM exhibit diminished ovarian reserve, characterized by reduced oocyte quantity and quality. Fibrotic changes in the ovarian tissue surrounding the OEM create a disruptive microenvironment for follicular growth and development.

STUDY DESIGN, SIZE, DURATION

This is a cross-sectional study aimed to elucidate the molecular mechanisms underlying the impact of OEM on follicular development. Initially, miRNA expression profiles in follicular fluid (FF) samples were sequenced from patients with infertility related to OEM (N = 3) and male factor (MF) infertility (N = 3), with the latter serving as the control group. Differentially expressed miRNAs were validated in additional samples from each group (N = 55 in OEM group and N = 45 in MF group) to confirm candidate miRNAs. The study also investigated indicators associated with GCs dysfunction in vitro on rat GCs. Subsequently, rat models of OEM were established through endometrial allogeneic transplantation, and fertility experiments were conducted to assess the let-7/IGF1R axis response to OEM in vivo. Patient samples were collected between May 2018 and April 2019, and the mechanistic study was conducted over the subsequent three years.

PARTICIPANTS/MATERIALS, SETTING, METHODS

FF and GC samples were obtained from infertile patients undergoing IVF treatment for OEM and MF related infertility. miRNA expression profiles in FF samples were analyzed using second-generation high-throughput sequencing technology, and candidate miRNAs were validated through quantitative PCR (qPCR). In the in vitro experiments conducted with rat GCs, cell proliferation was assessed using the CCK-8 assay, while steroid hormone concentrations were measured using chemiluminescence. ATP content was determined with an ATP assay kit, and levels of ROS were quantified using flow cytometry. A dual luciferase reporter gene assay was employed to identify the target gene of let-7 based on the construction of a IGF1R reporter gene plasmid using 293T cells. Western blotting was utilized to evaluate the expression of IGF1R in GCs, as well as its downstream proteins, and changes in signaling pathways following let-7 agomir/antagomir transfection and/or Igf1r silencing. In the in vivo OEM rat models, alterations in ovarian structure and cyst morphology were observed using hematoxylin and eosin staining. The expressions of let-7 and Igf1r in GCs were evaluated through qPCR, while variations in IGF1R expression were investigated with immunohistochemistry.

MAIN RESULTS AND THE ROLE OF CHANCE

The cohort of patients with ovarian OEM in this study exhibited significantly decreased antral follicle counts, oocyte retrieval numbers, and normal fertilization rates compared to the control group with MF. The expression of the let-7 miRNA family was markedly upregulated in the FF and GCs of OEM patients. Transfection of rat GCs with let-7 agonists diminished the functions of GCs, including disrupted cell proliferation, mitochondrial oxidative phosphorylation, and steroid hormone secretion, while transfection of rat GCs with let-7 antagonists caused the opposite effects. Luciferase reporter gene experiments confirmed that let-7 complementarily bound to the 3'-untranslated regions of IGF1R. Stimulation of let-7 expression in rat GCs led to a significant decrease in IGF1R expression, while inhibition of let-7 increased IGF1R expression. The expression of IGF1R in the GCs of OEM patients was also significantly reduced compared to MF patients. Silencing of Igf1r led to the dysfunction of GCs, similar to the effects of let-7 agonization, as demonstrated by the downregulation of key proteins involved in cell proliferation (CCND2 and CCND3) and oestradiol synthesis, as well as an increase in progesterone synthesis (StAR), while implicating the PI3K-Akt and MAPK signaling pathways. The antagonistic effect of let-7 on GCs was ineffective when Igf1r was silenced. Conversely, the agonistic effect of let-7 on GCs could be reversed by stimulation with the IGF1R ligand IGF-1. These findings suggested that let-7 regulated the proliferation, differentiation, and ATP synthesis of GCs through targeting IGF1R. The OEM rat model demonstrated alterations in ovarian morphology and structure, along with reduced fertility. Let-7 expression was significantly upregulated in GCs of OEM rats compared to normal rats, while Igf1r and IGF1R expression in pre-ovulatory follicular GCs were notably downregulated, supporting the notion that elevated let-7 expression in the follicular microenvironment of OEM inhibited IGF1R, leading to abnormal GC function and impacting fertility at the molecular level.

LARGE SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

The synthesis and secretion mechanisms of steroid hormones are intricate and complex. Some enzymes that regulate oestrogen synthesis also play a role in progesterone synthesis. Moreover, certain receptors can respond to multiple hormone signals. Therefore, in this study, the expression patterns of key enzymes such as CYP17A, CYP11A1, HSD3B2, StAR, and receptors including AR, LHCGR, FSHR, ESR2, might be influenced by various factors and might not demonstrate complete consistency.

WIDER IMPLICATIONS OF THE FINDINGS

Future research will concentrate on investigating the potential impact of ovarian stromal cells on the external microenvironment of follicle growth. Additionally, screening for small molecule drugs that target let-7 and IGF1R actions can be conducted to intervene and modify the ovarian microenvironment, ultimately enhancing ovarian function.

STUDY FUNDING/COMPETING INTEREST(S)

This study received funding from the National Natural Science Foundation of China (grant number 82301851 to L.B.S., grant numbers U23A20403 and U20A20349 to S.Y.Z., and grant number 82371637 to Y.D.D.) and the Natural Science Foundation of Zhejiang Province (grant LTGY23H040010 to F.Z.). The authors have no conflicts of interest to declare.

Granulosa Cells-Related MicroRNAs in Ovarian Diseases: Mechanism, Facts and Perspectives

MicroRNAs (miRNAs) are a class of short single-stranded, noncoding RNAs that affect the translation of mRNAs by imperfectly binding to homologous 3'UTRs. Research on miRNAs in ovarian diseases is constantly expanding because miRNAs are powerful regulators of gene expression and cellular processes and are promising biomarkers. miRNA mimics, miRNA inhibitors and molecules targeting miRNAs (antimiRs) have shown promise as novel therapeutic agents in preclinical development. Granulosa cells (GCs) are supporting cells for developing oocytes in the ovary. GCs regulate female reproductive health by producing sex hormones and LH receptors. Increasing research has reported the relevance of miRNAs in GC pathophysiology. With in-depth studies of disease mechanisms, there are an increasing number of studies on the biomolecular pathways of miRNAs in gynecology and endocrinology. In the present review, we summarize the different functions of GC-related microRNAs in various ovarian disorders, such as polycystic ovary syndrome, premature ovarian insufficiency, premature ovarian failure and ovarian granulosa cell tumors.

The Estrogen-Autophagy Axis: Insights into Cytoprotection and Therapeutic Potential in Cancer and Infection

Macroautophagy, commonly referred to as autophagy, is an essential cytoprotective mechanism that plays a significant role in cellular homeostasis. It has emerged as a promising target for drug development aimed at treating various cancers and infectious diseases. However, the scientific community has yet to reach a consensus on the most effective approach to manipulating autophagy, with ongoing debates about whether its inhibition or stimulation is preferable for managing these complex conditions. One critical factor contributing to the variability in treatment responses for both cancers and infectious diseases is estrogen, a hormone known for its diverse biological effects. Given the strong correlations observed between estrogen signaling and autophagy, this review seeks to summarize the intricate molecular mechanisms that underlie the dual cytoprotective effects of estrogen signaling in conjunction with autophagy. We highlight recent findings from studies that involve various ligands, disease contexts, and cell types, including immune cells. Furthermore, we discuss several factors that regulate autophagy in the context of estrogen's influence. Ultimately, we propose a hypothetical model to elucidate the regulatory effects of the estrogen-autophagy axis on cell fate. Understanding these interactions is crucial for advancing our knowledge of related diseases and facilitating the development of innovative treatment strategies.

LSD1 promotes the FSH responsive follicle formation by regulating autophagy and repressing Wt1 in the granulosa cells

In a growing follicle, the survival and maturation of the oocyte largely depend on support from somatic cells to facilitate FSH-induced mutual signaling and chemical communication. Although apoptosis and autophagy in somatic cells are involved in the process of FSH-induced follicular development, the underlying mechanisms require substantial study. According to our study, along with FSH-induced antral follicles (AFs) formation, both lysine-specific demethylase 1 (LSD1) protein levels and autophagy increased simultaneously in granulosa cells (GCs) in a time-dependent manner, we therefore evaluated the importance of LSD1 upon facilitating the formation of AFs correlated to autophagy in GCs. Conditional knockout of Lsd1 in GCs resulted in significantly decreased AF number and subfertility in females, accompanied by marked suppression of the autophagy in GCs. On the one hand, depletion of Lsd1 resulted in accumulation of Wilms tumor 1 homolog (WT1), at both the protein and mRNA levels. WT1 prevented the expression of FSH receptor (Fshr) in GCs and thus reduced the responsiveness of the secondary follicles to FSH induction. On the other hand, depletion of LSD1 resulted in suppressed level of autophagy by upregulation of ATG16L2 in GCs. We finally approved that LSD1 contributed to these sequential activities in GCs through its H3K4me2 demethylase activity. Therefore, the importance of LSD1 in GCs is attributable to its roles in both accelerating autophagy and suppressing WT1 expression to ensure the responsiveness of GCs to FSH during AFs formation.

Sodium butyrate alleviates right ventricular hypertrophy in pulmonary arterial hypertension by inhibiting H19 and affecting the activation of let-7g-5p/IGF1 receptor/ERK

Pulmonary arterial hypertension (PAH) is a complex and fatal cardio-pulmonary vascular disease. Decompensated right ventricular hypertrophy (RVH) caused by cardiomyocyte hypertrophy often leads to fatal heart failure, the leading cause of mortality among patients. Sodium butyrate (SB), a compound known to reduce cardiac hypertrophy, was examined for its potential effect and the underlying mechanism of SB on PAH-RVH. The in vivo study showed that SB alleviated RVH and cardiac dysfunction, as well as improved life span and survival rate in MCT-PAH rats. The in vivo and in vitro experiments showed that SB could attenuate cardiomyocyte hypertrophy by reversing the expressions of H19, let-7g-5p, insulin-like growth factor 1 receptor (IGF1 receptor), and pERK. H19 inhibition restored the level of let-7g-5p and prevented the overexpression of IGF1 receptor and pERK in hypertrophic cardiomyocytes. In addition, dual luciferase assay revealed that H19 demonstrated significant binding with let-7g-5p, acting as its endogenous RNA. Briefly, SB attenuated PAH-RVH by inhibiting the H19 overexpression, restoring the level of let-7g-5p, and hindering IGF1 receptor/ERK activation.

miRNA-29-3p targets PTEN to regulate follicular development through the PI3K/Akt/mTOR signaling pathway

Granulosa cells play a pivotal role in growth, development and ovulation of ovarian follicle. Simultaneously, autophagy and apoptosis processes are crucial determinants in the destiny of granulosa cells. Within this context, miR-29-3p, known to regulate a broad spectrum of biological processes and critical for tumor detection, prognosis, and treatment, is poised to clarify its roles in both autophagy and apoptosis. To enhance the understanding of the influence of miR-29-3p on follicular development, our study primarily delved into the realms autophagy and apoptosis. We employed a well-established chicken follicular atrophy model achieved through subcutaneous injection of tamoxifen (TMX) into hens. qPCR analysis revealed a significant decrease in the expression of miR-29-3p within the atrophic follicles. In our in vitro experiments with cultured chicken primary granulosa cells, miR-29-3p emerged as a novel microRNA capable of impeding autophagy and apoptosis when transfected with miR-29-3p mimics and inhibitors. Results from luciferase reporter assays corroborated that PTEN is a legitimate target of miR-29-3p. Unlike miR-29-3p, PTEN appeared to foster autophagy and apoptosis in chicken granulosa cells. Moreover, our findings uncovered that miR-29-3p facilitates the phosphorylation of Akt and mTOR proteins by targeting PTEN in chicken granulosa cells. In conclusion, the findings of this study suggest that miR-29-3p, through its targeting of PTEN via the Akt/mTOR signaling pathway, exerts inhibitory effects on autophagy and apoptosis. These effects may hold significant importance in the context of follicular development.

High Prolactin Concentration Induces Ovarian Granulosa Cell Oxidative Stress, Leading to Apoptosis Mediated by L-PRLR and S-PRLR

High prolactin (PRL) concentration has been shown to induce the apoptosis of ovine ovarian granulosa cells (GCs), but the underlying mechanisms are unclear. This study aimed to investigate the mechanism of apoptosis induced by high PRL concentration in GCs. Trial 1: The optimal concentration of glutathion was determined according to the detected cell proliferation. The results showed that the optimal glutathione concentration was 5 μmol/mL. Trial 2: 500 ng/mL PRL was chosen as the high PRL concentration. The GCs were treated with 0 ng/mL PRL (C group), 500 ng/mL PRL (P group) or 500 ng/mL PRL, and 5 μmol/mL glutathione (P-GSH group). The results indicated that the mitochondrial respiratory chain complex (MRCC) I-V, ATP production, total antioxidant capacity (T-AOC), superoxide dismutase (SOD), and thioredoxin peroxidase (TPx) in the C group were higher than those in the P group (p < 0.05), while they were lower than those in the P-GSH group (p < 0.05). Compared to the C group, the P group exhibited elevated levels of reactive oxygen species (ROS) and apoptosis (p < 0.05) and increased expression of ATG7 and ATG5 (p < 0.05). However, MRCC I-V, ATP, SOD, A-TOC, TPx, ROS, and apoptosis were decreased after the addition of glutathione (p < 0.05). The knockdown of either L-PRLR or S-PRLR in P group GCs resulted in a significant reduction (p < 0.05) in MRCC I-V, ATP, T-AOC, SOD and TPx, while the overexpression of either receptor showed an opposite trend (p < 0.05). Our findings suggest that high PRL concentrations induce apoptotic cell death in ovine ovarian GCs by downregulating L-PRLR and S-PRLR, activating oxidative stress and autophagic pathways.

The effect of sitagliptin combined with rosiglitazone on autophagy and inflammation in polycystic ovary syndrome by regulating PI3K/AKT/mTOR and TLR4/NF-κB pathway

Polycystic ovary syndrome (PCOS) is a common endocrine and metabolic disorder. Sitagliptin (Sit) and rosiglitazone (Ros) are widely used to treat PCOS, but the mechanism is unclear. This study explored the mechanism that Sit and Ros inhibited autophagy and inflammation in PCOS. In this study, 50 female SD rats were divided into 5 groups (n = 10): control, PCOS, Sit, Ros, and Sit+Ros group. The body weight and ovarian weight were measured 2 h after the last administration, and fasting blood glucose, insulin levels were determined. Lipid metabolism and pathological changes were detected by an automatic biochemical analyzer and HE staining. Sex hormone, oxidative stress and inflammatory levels were detected by ELISA. PCR detected IL-18, TNF-α, IL-6, IL-1β, ATG3, and ATG12 mRNA. The PI3K/AKT/mTOR, TLR4/NF-κB pathway and autophagy-related proteins were detected by western blot. Finally, the number of autophagolysosomes was detected by transmission electron microscopy. Sit or Ros alone reduced body weight, ovarian weight, fasting blood glucose, and insulin levels in PCOS rats. It also improved lipid metabolism, sex hormone levels, oxidative stress and pathological changes, restored the estrous cycle, and corpus luteum quantity. In addition, it could reduce the levels of IL-18, TNF-α, IL-6, IL-1β, ATG3, and ATG12 mRNA, inhibit the expression of Beclin1, LC3, PI3K/AKT/mTOR, and TLR4/NF-κB pathway proteins. The Sit+Ros group was more effective than single administration. In conclusion, Sit+Ros inhibited the PI3K/AKT/mTOR, TLR4/NF-κB pathways, thereby inhibiting the autophagy and inflammation of PCOS rats, which will provide a theoretical basis for PCOS.

MiR-34a-5p promotes autophagy and apoptosis of ovarian granulosa cells via the Hippo-YAP signaling pathway by targeting LEF1 in chicken

Follicular atresia is a natural physiological phenomenon in poultry reproduction. It is well known that follicular atresia is caused by both autophagy and apoptosis of granulosa cells. In current experiment, we evaluated the function of miR-34a-5p on autophagy and apoptosis in chicken follicular atresia. First, the follicular atresia model of chicken was successfully constructed by subcutaneous injection of tamoxifen (TMX), and found the expression of miR-34a-5p in the atresia follicles obviously increased. Then, we confirmed that miR-34a-5p accelerates autophagy and apoptosis of chicken granulose cells in vitro, and miR-34a-5p could induce apoptosis by mediating autophagy. Mechanistically, lymphoid enhancer binding factor 1 (LEF1) was deemed as a target gene for miR-34a-5p. On the contrary, LEF1 overexpression attenuated the autophagy and apoptosis of chicken granular cells. In addition, it was confirmed that the miR-34a-5p/LEF1 axis plays a regulatory role in chicken granulosa cells by mediating the Hippo-YAP signaling pathway. Taken together, this study demonstrated that miR-34a-5p contributes to autophagy and apoptosis of chicken follicular granulosa cells by targeting LEF1 to mediate the Hippo-YAP signaling pathway.

Guizhi Fuling Wan reduces autophagy of granulosa cell in rats with polycystic ovary syndrome via restoring the PI3K/AKT/mTOR signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Guizhi Fuling Wan (GFW) is a traditional Chinese medicine used to remove blood stasis and dissipate phlegm for treating gynecological diseases that was invented by Zhang Zhongjing in the Eastern Han dynasty. In recent years, GFW has been widely used to treat patients with polycystic ovary syndrome (PCOS). Clinical and animal studies have shown that it is effective in the treatment of PCOS, but its mechanism is unknown. Generally, it works by regulating autophagy via the PI3K/AKT/mTOR signaling pathway.

AIM OF THE STUDY

This study investigated the effects and mechanism of GFW in PCOS rats with insulin resistance (IR) in order to provide better understanding of its observed clinical effects and a theoretical basis for the study of traditional Chinese medicine.

MATERIALS AND METHODS

Eighty-four female Sprague-Dawley rats were randomly divided into seven groups (n = 12 per group): 1) control, 2) PCOS model, 3) low-dose GFW, 4) medium-dose GFW, 5) high-dose GFW, 6) metformin, and 7) medium-dose GFW plus LY294002. In all non-control groups, we induced PCOS through daily letrozole combined with intragastric high-fat emulsion for 21 days. After treatment, rats were sacrificed and serum follicle-stimulating hormone (FSH), testosterone (T), progesterone, luteinizing hormone (LH), 17β-estradiol, fasting insulin (FINS), and fasting plasma glucose levels were measured by enzyme-linked immunosorbent assay (ELISA). The LH/FSH ratios and HOMA-IR values were calculated. Ovarian morphology was observed by hematoxylin and eosin staining, and all follicles were counted under a microscope. MDC-positive vesicles were used as markers to detect autophagy, and the expression levels of p62, Beclin1, and LC3-II were examined by immunostaining. Western blotting was used to measure PI3K/AKT/mTOR pathway activation, granulosa cell apoptosis, and autophagy.

RESULTS

Compared with the PCOS model group, GFW-treated rats had less atretic and cystic follicles, and more mature follicles and corpus lutea. The GFW-treated rats had lower serum T, LH, and FINS levels than the PCOS model group, as well as lower LH/FSH ratios and HOMA-IR values. GFW treatment resulted in significantly reduced levels of cleaved-Caspase-3, cleaved-Caspase-9, BAX, Beclin1, Atg5, and LC3-II. Phosphorylation of PI3K, AKT, and mTOR was significantly higher in GFW-treated rats compared with the PCOS model group. The phosphorylation of PI3K, AKT, and mTOR was decreased with the use of a PI3K antagonist.

CONCLUSIONS

Our results indicate that GFW inhibited granulosa cell autophagy and promoted follicular development to attenuate ovulation disorder in PCOS-IR rats. This was associated with activation of the PI3K/AKT/mTOR signaling pathway.

The AMPK-mTOR axis requires increased MALAT1 expression for promoting granulosa cell proliferation in endometriosis

Endometriosis is a common reproductive disorder in women, with a global prevalence of 10-15%. Long noncoding RNAs (lncRNAs) are critical to gene transcription, cell cycle modulation and immune response. The lncRNA metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) reportedly mediates autophagy of endometrial stromal cells in endometriosis. The present study aimed to evaluate the role and mechanism of MALAT1 in granulosa cells (GCs) in endometriosis. Consequently, MALAT1 expression was upregulated in GCs obtained from patients with endometriosis and in the steroidogenic human granulosa-like tumor cell line KGN. However, MALAT1 knockdown consequently decreased the proliferation and viability of these cells, as determined by MTT and 5-ethynyl-2'-deoxyuridine staining assays. Both Annexin V-fluorescein isothiocyanate/propidium iodide flow cytometry and western blotting performed to detect proapoptotic factors indicated that MALAT1 depletion might promote KGN cell apoptosis. Furthermore, MALAT1 knockdown increased GC autophagy, as evidenced by microtubule-associated protein 1A/1B-light chain 3 (LC3) cleavage upregulation and p62 degradation. In addition, although 5'-AMP-activated protein kinase (AMPK) mRNA expression and protein levels decreased in GCs obtained from patients with endometriosis and KGN cells, MALAT1 knockdown restored AMPK levels. However, addition of BML-275 (MALAT1 inhibitor) to MALAT1-knockdown KGN cells recovered their viability and proliferative capacity and simultaneously reduced their apoptotic and autophagic capacity. Therefore, MALAT1 may regulate GC proliferation via AMPK-mTOR-mediated cell apoptosis and autophagy.

miRNA-21-3p targeting of FGF2 suppresses autophagy of bovine ovarian granulosa cells through AKT/mTOR pathway

It is widely thought that the main reason for ovarian follicular atresia is apoptosis of granulosa cells, however, accumulating evidence suggests that autophagy plays a role in the fate of granulosa cells. Although epigenetic regulation including miR-21-3p associated with autophagy process has been reported in many cancer types, nevertheless, the mechanism of miR-21-3p in bovine ovary is poorly understood. In the present study, bovine ovarian granulosa cells (BGCs) were used as a model to elucidate the autophagy and role of miR-21-3p in a cattle ovary. The results from gene expression and tagged autophagosomes showed the autophagy in BGCs and miR-21-3p was identified as an important miRNA regulating autophagy of BGCs. The current results indicated that FGF2 was a validated target of miR-21-3p in autophagy regulation of BGCs according to the results from FGF2 luciferase reporter assays and FGF2 overexpression (oe-FGF2) or small interference (si-FGF2). Transfection of miR-21-3p mimic and si-FGF2 plasmids resulted in decreasing phosphorylated AKT and mTOR, while transfection of miR-21-3p inhibitor and oe-FGF2 increased the phosphorylated level of AKT and mTOR in BGCs. These data indicate that regulation of miR-21-3p on BGCs autophagy through AKT/mTOR pathway. In summary, this study suggests that miR-21-3p targets FGF2 to inhibit BGCs autophagy by repressing AKT/mTOR signaling.

Supraphysiological Concentrations of Bisphenol A Alter the Expression of Extracellular Vesicle-Enriched miRNAs From Human Primary Granulosa Cells

Bisphenol A (BPA) is a widely used chemical that has been detected in follicular fluid and associated with adverse reproductive effects. Granulosa cells have an important role in follicular growth and oocyte maturation, however, little is known about the biological mechanisms of BPA toxicity on human granulosa cells. In this study, we exposed primary granulosa cells to different concentrations of BPA (0, 20, 200, 2000, and 20 000 ng/ml) and used quantitative polymerase chain reaction to measure the expression levels of miRNAs enriched in extracellular vesicles (EV-enriched miRNAs), and cellular levels of selected target genes of differentially expressed EV-enriched miRNAs. We found that exposure to 20 000 ng/ml BPA was associated with decreased levels of EV-miR-27b-3p (FC = 0.58, p = .04) and increased levels of its biologically relevant target genes FADD (FC = 1.22, p = .01), IGF1 (FC = 1.59, p = .06), and PPARG (FC = 1.73, p = .001) as compared with the control. In addition, we observed that under the same exposure conditions, the expression levels of miR-27b-3p in granulosa cells were also downregulated (FC = 0.65, p = .03) as compared with the control. Our findings suggest that both cellular and extracellular changes in gene expression may mediate BPA toxicity in granulosa cells.

MicroRNAs regulate granulosa cells apoptosis and follicular development - A review

Objective

MicroRNAs (miRNAs) are the most abundant small RNAs. Approximately 2,000 annotated miRNAs genes have been found to be differentially expressed in ovarian follicles during the follicular development (FD). Many miRNAs exert their regulatory effects on the apoptosis of follicular granulosa cells (FGCs) and FD. However, accurate roles and mechanism of miRNAs regulating apoptosis of FGCs remain undetermined.

Methods

In this review, we summarized the regulatory role of each miRNA or miRNA cluster on FGCs apoptosis and FD on the bases of 41 academic articles retrieved from PubMed and web of science and other databases.

Results

Total of 30 miRNAs and 4 miRNAs clusters in 41 articles were reviewed and summarized in the present article. Twenty nine documents indicated explicitly that 24 miRNAs and miRNAs clusters in 29 articles promoted or induced FGCs apoptosis through their distinctive target genes. The remaining 10 miRNAs and miRNAs of 12 articles inhibited FGCs apoptosis. MiRNAs exerted modulation actions by at least 77 signal pathways during FGCs apoptosis and FD.

Conclusion

We concluded that miRNAs or miRNAs clusters could modulate the apoptosis of GCs (including follicular GCs, mural GCs and cumulus cells) by targeting their specific genes. A great majority of miRNAs show a promoting role on apoptosis of FGCs in mammals. But the accurate mechanism of miRNAs and miRNA clusters has not been well understood. It is necessary to ascertain clearly the role and mechanism of each miRNA or miRNA cluster in the future. Understanding precise functions and mechanisms of miRNAs in FGCs apoptosis and FD will be beneficial in developing new diagnostic and treatment strategies for treating infertility and ovarian diseases in humans and animals.

Interaction among inflammasome, autophagy and non-coding RNAs: new horizons for drug

Autophagy and inflammasomes are shown to interact in various situations including infectious disease, cancer, diabetes and neurodegeneration. Since multiple layers of molecular regulators contribute to the interplay between autophagy and inflammasome activation, the detail of such interplay remains largely unknown. Non-coding RNAs (ncRNAs), which have been implicated in regulating an expanding list of cellular processes including immune defense against pathogens and inflammatory response in cancer and metabolic diseases, may join in the crosstalk between inflammasomes and autophagy in physiological or disease conditions. In this review, we summarize the latest research on the interlink among ncRNAs, inflammasomes and autophagy and discuss the emerging role of these three in multiple signaling transduction pathways involved in clinical conditions. By analyzing these intriguing interconnections, we hope to unveil the mechanism inter-regulating these multiple processes and ultimately discover potential drug targets for some refractory diseases.

Autophagy in hypoxic ovary

Oxygen deprivation affects human health by modulating system as well as cellular physiology. Hypoxia generates reactive oxygen species (ROS), causes oxidative stress and affects female reproductive health by altering ovarian as well as oocyte physiology in mammals. Hypoxic conditions lead to several degenerative changes by inducing various cell death pathways like autophagy, apoptosis and necrosis in the follicle of mammalian ovary. The encircling somatic cell death interrupts supply of nutrients to the oocyte and nutrient deprivation may result in the generation of ROS. Increased level of ROS could induce granulosa cells as well as oocyte autophagy. Although autophagy removes damaged proteins and subcellular organelles to maintain the cell survival, irreparable damages could induce cell death within intra-follicular microenvironment. Hypoxia-induced autophagy is operated through 5' AMP activated protein kinase-mammalian target of rapamycin, endoplasmic reticulum stress/unfolded protein response and protein kinase C delta-c-junN terminal kinase 1 pathways in a wide variety of somatic cell types. Similar to somatic cells, we propose that hypoxia may induce granulosa cell as well as oocyte autophagy and it could be responsible at least in part for germ cell elimination from mammalian ovary. Hypoxia-mediated germ cell depletion may cause several reproductive impairments including early menopause in mammals.

MiR-126* is a novel functional target of transcription factor SMAD4 in ovarian granulosa cells

Both SMAD4 and miR-126* have been proven to be involved in granulosa cell (GC) apoptosis and even follicular atresia, through commonly regulating follicle-stimulating hormone receptor (FSHR), the FSH-specific transmembrane receptor of GCs. However, the regulatory relationship between them in GCs is still unknown. In this study, we report that SMAD4 suppresses the expression of miR-126* and impairs its function in GCs of the porcine ovary by acting as a transcription factor. A classic SMAD4-binding element (SBE) site was found in the promoter of miR-126* by using in silico methods. Luciferase assay, qRT-PCR, and ChIP assay proved that SMAD4 serves as a transcriptional repressor and directly binds to SBE site within miR-126* gene promoter, which further reduces miR-126* gene expression and inhibits its transcriptional activity in GCs. Furthermore, SMAD4 also controls miR-126*-mediated expression of FSHR (a direct target of miR-126* in GCs). In addition, we prove that SMAD4 induces CYP19A1 expression (encodes aromatase, the key enzyme for oestrogen biosynthesis) and inhibits GC apoptosis through the miR-126*/FSHR axis. Taken together, our findings not only established a direct link between SMAD4 and miRNA-126*, two key factors of GC apoptosis, but also revealed an important way in which the SMAD4 regulates GC function, the miRNA-126*/FSHR axis.

The Role of microRNAs in Ovarian Granulosa Cells in Health and Disease

The granulosa cell (GC) is a critical somatic component of the ovary. It is essential for follicle development by supporting the developing oocyte, proliferating and producing sex steroids and disparate growth factors. Knowledge of the GC's function in normal ovarian development and function, and reproductive disorders, such as polycystic ovary syndrome (PCOS) and premature ovarian failure (POF), is largely acquired through clinical studies and preclinical animal models. Recently, microRNAs have been recognized to play important regulatory roles in GC pathophysiology. Here, we examine the recent findings on the role of miRNAs in the GC, including four related signaling pathways (Transforming growth factor-β pathway, Follicle-stimulating hormones pathway, hormone-related miRNAs, Apoptosis-related pathways) and relevant diseases. Therefore, miRNAs appear to be important regulators of GC function in both physiological and pathological conditions. We suggest that targeting specific microRNAs is a potential therapeutic option for treating ovary-related diseases, such as PCOS, POF, and GCT.

How does estrogen work on autophagy?

Macroautophagy/autophagy is vital for intracellular quality control and homeostasis. Therefore, careful regulation of autophagy is very important. In the past 10 years, a number of studies have reported that estrogenic effectors affect autophagy. However, some results, especially those regarding the modulatory effect of 17β-estradiol (E2) on autophagy seem inconsistent. Moreover, several clinical trials are already in place combining both autophagy inducers and autophagy inhibitors with endocrine therapies for breast cancer. Not all patients experience benefit, which further confuses and complicates our understanding of the main effects of autophagy in estrogen-related cancer. In view of the importance of the crosstalk between estrogen signaling and autophagy, this review summarizes the estrogenic effectors reported to affect autophagy, subcellular distribution and translocation of estrogen receptors, autophagy-targeted transcription factors (TFs), miRNAs, and histone modifications regulated by E2. Upon stimulation with estrogen, there will always be opposing functional actions, which might occur between different receptors, receptors on TFs, TFs on autophagy genes, or even histone modifications on transcription. The huge signaling network downstream of estrogen can promote autophagy and reduce overstimulated autophagy at the same time, which allows autophagy to be regulated by estrogen in a restricted range. To help understand how the estrogenic regulation of autophagy affects cell fate, a hypothetical model is presented here. Finally, we discuss some exciting new directions in the field. We hope this might help to better understand the multiple associations between estrogen and autophagy, the pathogenic mechanisms of many estrogen-related diseases, and to design novel and efficacious therapeutics. Abbreviations: AP-1, activator protein-1; HATs, histone acetyltransferases; HDAC, histone deacetylases; HOTAIR, HOX transcript antisense RNA.

Comparative profiling of differentially expressed microRNAs in estrous ovaries of Kazakh sheep in different seasons

Seasonal estrus is a critical limiting factor for animal fecundity. However, estrus occurs in some seasonally estrous sheep in the non-breeding season, and this phenomenon involves changes in ovarian biology. Previous studies indicated that small RNAs, such as microRNAs (miRNAs), play important regulatory roles in ovarian biology. Differentially expressed miRNAs in the ovaries of estrous sheep were identified using Solexa sequencing technology. A total of 423 known miRNAs were identified in ovaries of estrous sheep in the breeding season and non-breeding season. In the comparison of these two groups, 48 miRNAs were identified that were differentially expressed between the two groups (including 5 up-regulated and 43 down-regulated miRNAs). KEGG pathway analysis revealed that the target genes of some differentially expressed miRNAs were involved in pathways related to reproductive hormone signaling and follicular development. Furthermore, the levels of estradiol (E2), progesterone (P4), luteinizing hormone (LH) and follicle-stimulating hormone (FSH) were lower in anestrus sheep than in sheep during the breeding season. Upon combining the pathway enrichment analysis, target gene expression and hormone measurement results, we suggest that these differentially expressed miRNAs might influence ovarian activity in the non-breeding season by regulating the above pathways. The identification of miRNAs that are differentially expressed between ovines in the breeding season and non-breeding season will contribute to our understanding of the role of miRNAs in estrus regulation, and these data may provide a basis for regulating estrus in sheep during the non-breeding season.

MicroRNA let-7g inhibits angiotensin II-induced endothelial senescence via the LOX-1-independent mechanism

Endothelial senescence leads to cell dysfunction, which in turn eventually results in cardiovascular disease. Identifying factors that regulate endothelial senescence may provide insight into the pathogenesis of aging. Insulin-like growth factor (IGF) signaling has a significant role in the physiology of endothelial cells (ECs). Overactivation of IGF signaling has been implicated in promoting the aging process. Lectin‑like oxidized low‑density lipoprotein (oxLDL) receptor‑1 (LOX‑1) is a scavenger receptor that mediates the internalization of oxLDL into cells. Previous studies by our group have indicated that microRNA let‑7g exerts an anti‑aging effect on ECs and also suppresses LOX-1 expression. Since LOX‑1 also induces the aging process, the present study we explored whether let‑7g still exerts an anti‑aging effect on ECs when LOX‑1 is suppressed. Angiotensin II (Ang II) was used to induce senescence in ECs. It was revealed that Ang II significantly increased the expression of aging markers, including β‑galactosidase, LOX‑1, IGF1 and its receptor IGF1R. On the contrary, Ang II decreased the expression of the anti‑aging gene sirtuin 1 (SIRT1). When LOX‑1 was knocked down by small interfering RNA, let‑7g still dose‑dependently decreased the expression of β‑galactosidase (β‑gal), LOX‑1, IGF1 and IGF1R, and SIRT1 was still upregulated. Using senescence‑associated β‑gal staining, it was confirmed that let‑7g exerts a LOX‑1‑independent anti‑aging effect on ECs. In conclusion, the present study demonstrated that let‑7g has an anti‑aging effect regardless of the presence or absence of LOX-1.

Administration of follicle-stimulating hormone induces autophagy via upregulation of HIF-1α in mouse granulosa cells

Recent studies reported the important role of autophagy in follicular development. However, the underlying molecular mechanisms remain elusive. In this study, we investigated the effect of follicle-stimulating hormone (FSH) on mouse granulosa cells (MGCs). Results indicated that autophagy was induced by FSH, which is known to be the dominant hormone regulating follicular development and granulosa cell (GC) proliferation. The activation of mammalian target of rapamycin (mTOR), a master regulator of autophagy, was inhibited during the process of MGC autophagy. Moreover, MHY1485 (an agonist of mTOR) significantly suppressed autophagy signaling by activating mTOR. The expression of hypoxia-inducible factor 1-alpha (HIF-1α) was increased after FSH treatment. Blocking hypoxia-inducible factor 1-alpha attenuated autophagy signaling. In vitro, CoCl₂-induced hypoxia enhanced cell autophagy and affected the expression of beclin1 and BCL2/adenovirus E1B interacting protein 3 (Bnip3) in the presence of FSH. Knockdown of beclin1 and Bnip3 suppressed autophagy signaling in MGCs. Furthermore, our in vivo study demonstrated that the FSH-induced increase in weight was significantly reduced after effectively inhibiting autophagy with chloroquine, which was correlated with incomplete mitophagy process through the PINK1-Parkin pathway, delayed cell cycle, and reduced cell proliferation rate. In addition, chloroquine treatment decreased inhibin alpha subunit, but enhanced the expression of 3 beta-hydroxysteroid dehydrogenase. Blocking autophagy resulted in a significantly lower percentage of antral and preovulatory follicles after FSH stimulation. In conclusion, our results indicate that FSH induces autophagy signaling in MGCs via HIF-1α. In addition, our results provide evidence that autophagy induced by FSH is related to follicle development and atresia.

MicroRNAs: New Insight in Modulating Follicular Atresia: A Review

Our understanding of the post-transcriptional mechanisms involved in follicular atresia is limited; however, an important development has been made in understanding the biological regulatory networks responsible for mediating follicular atresia. MicroRNAs have come to be seen as a key regulatory actor in determining cell fate in a wide range of tissues in normal and pathological processes. Profiling studies of miRNAs during follicular atresia and development have identified several putative miRNAs enriched in apoptosis signaling pathways. Subsequent in vitro and/or in vivo studies of granulosa cells have elucidated the functional role of some miRNAs along with their molecular pathways. In particular, the regulatory roles of some miRNAs have been consistently observed during studies of follicular cellular apoptosis. Continued work should gradually lead to better understanding of the role of miRNAs in this field. Ultimately, we expect this understanding will have substantial benefits for fertility management at both the in vivo or/and in vitro levels. The stable nature of miRNA holds remarkable promise in clinical use as a diagnostic tool and in reproductive medicine to solve the ever-increasing fertility problem. In this review, we summarize current knowledge of the involvement of miRNAs in follicular atresia, discuss the challenges for further work and pinpoint areas for future research.