MicroRNA in Ovarian Biology and Disease

miR-361-5p regulates SLC25A24 to maintain mitochondrial function and alleviate granulosa cell dysfunction in diminished ovarian reserve

BACKGROUND

The aim of this study was to investigate the role of miR-361-5p (a tumor suppressor) in regulating granulosa cell function by targeting SLC25A24, a key mitochondrial protein, to uncover potential therapeutic targets for diminished ovarian reserve (DOR).

METHODS

This study included patients undergoing assisted reproductive technology treatment at our hospital. Granulosa cells were isolated from follicular fluid, and KGN cells were used for in vitro experiments. miR-361-5p and SLC25A24 expression levels were manipulated using miRNA mimics and inhibitors, and their effects on cell viability, apoptosis, and mitochondrial function were assessed. Techniques employed included qRT-PCR, Western blot analysis, ELISA, JC-1 staining, and dual-luciferase reporter assays. Key quantitative metrics included changes in mitochondrial DNA (mtDNA), ATP production, and reactive oxygen species (ROS) levels.

RESULTS

miR-361-5p expression was significantly lower in DOR patients' granulosa cells compared to controls (P < 0.01). miR-361-5p inhibition markedly decreased KGN cells viability and increased apoptosis (P < 0.01), while miR-361-5p overexpression had the opposite effects (P < 0.01). SLC25A24 expression was inversely correlated with miR-361-5p levels, and its knockdown reversed the effects of miR-361-5p inhibition. Additionally, miR-361-5p modulation significantly affected mitochondrial function, with its overexpression reducing ROS levels and increasing ATP production (P < 0.01).

CONCLUSION

miR-361-5p plays a pivotal role in maintaining mitochondrial function and reducing KGN cells dysfunction by targeting SLC25A24. These findings offer new insights into the molecular mechanisms of DOR and highlight miR-361-5p as a potential therapeutic target to enhance ovarian reserve and improve fertility outcomes.

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.

Effect of follicle-stimulating hormone and luteinizing hormone on apoptosis, autophagy, and the release and reception of some steroid hormones in yak granulosa cells through miR-23a/ASK1 axis

Follicle-stimulating hormone (FSH), luteinizing hormone (LH), miR-23a, apoptosis signal-regulating kinase 1(ASK1)/c-Jun N-terminal kinase (JNK), autophagy and apoptosis play crucial roles in follicular development. However, their role in yak granulosa cells (GCs) remains unknown. Therefore, we examined the effect of miR-23a, ASK1, FSH, and LH on apoptosis, autophagy, and the release and reception of some steroid hormones in these cells. Our results showed that miR-23a overexpression significantly increased the abundance of Beclin1, the LC3II/I ratio, and the number of Ad-mRFP-GFP-LC3-labeled autophagosomes, and decreased p62 abundance. Additionally, Bax abundance and the number of terminal deoxynucleotidyl transferase deoxynucleotide triphosphate nick end labeling-positive cells were reduced, while Bcl2 expression was increased. Overexpression of miR-23a also significantly increased the abundance of estradiol receptor α (ER-α) and β (ER-β) and the concentrations of estradiol (E2), progesterone (P4) in yak GCs. Here, treating yak GCs with miR-23a decreased ASK1 expression, which regulates ASK1/JNK-mediated apoptosis, autophagy, E2 and P4 levels, and ER-α/β abundance. In contrast, treatment of yak GCs with FSH (10 μg/mL) and LH (100 μg/mL) increased miR-23a abundance, regulating the subsequent effect on ASK1/JNK-mediated apoptosis, autophagy, ER-α/β abundance, and E2 and P4 concentrations. In conclusion, miR-23a enhances autophagy in yak GCs, attenuates apoptosis, and increases ER-α/β abundance and E2 and P4 concentrations by downregulating ASK1. Additionally, FSH and LH can regulate these effects of miR-23a by altering its expression. These results provide important insights that can inform the development of strategies to reduce abnormal follicular atresia and improve the reproductive rate of yaks.

Cancer cell-derived exosomal miR-20a-5p inhibits CD8+ T-cell function and confers anti-programmed cell death 1 therapy resistance in triple-negative breast cancer

Circulating miRNAs (cirmiRNAs) can be packaged into the exosomes, participating in intercellular communication, which affects the malignant progression and therapy resistance of triple-negative breast cancer (TNBC). Currently, immune checkpoint inhibitors that regulate T-cell function, especially antibodies against programmed cell death 1 (PD-1) or its ligand PD-L1, are emerging as new promising therapy for TNBC patients. However, only very limited patients showed complete or partial response to anti-PD-1 treatment. Dysfunction of CD8+ T cells is one of the key reasons for the immune escape of TNBC. The regulation of exosome-derived cirmiRNAs on CD8+ T cells in TNBC deserves more investigation. Here, the cirmiR-20a-5p level was significantly upregulated in the plasma of TNBC patients and culture supernatant of TNBC cells. High abundance of cirmiR-20a-5p was correlated with a worse prognosis of TNBC. cirmiR-20a-5p was secreted in the form of exosomes by TNBC cells. Exosomal cirmiR-20a-5p was internalized into CD8+ T cells and resulted into the dysfunction of CD8+ T. A mechanism study uncovered that cirmiR-20a-5p targeted the nuclear protein ataxia-telangiectasia (NPAT) and decreased NPAT expression in CD8+ T cells. An in vivo xenograft mouse model showed that cirmiR-20a-5p conferred TNBC to anti-PD-1 treatment resistance. Collectively, these findings indicated that cirmiR-20a-5p released by TNBC cells via exosome promotes cancer cell growth and leads to the immunosuppression by inducing CD8+ T cell dysfunction. This study suggests that targeting cirmiR-20a-5p might be a novel strategy for overcoming the resistance of TNBC to anti-PD-1 immunotherapy.

A glance into the roles of microRNAs (exosomal and non-exosomal) in polycystic ovary syndrome

Polycystic ovarian syndrome (PCOS) is a common endocrine disorder in women of reproductive age. The clinical symptoms include hyperandrogenism, chronic anovulation, and multiple ovarian cysts. PCOS is strongly associated with obesity and insulin resistance. MicroRNAs (miRNAs) are a group of short non-coding RNAs that play a role in the post-transcriptional regulation of gene expression and translational inhibition. They play a vital role in the regulation of multiple metabolic and hormonal processes as well as in oocyte maturation and folliculogenesis in the female reproductive system. miRNAs can be used as diagnostic biomarkers or therapeutic targets because of their stability. The encapsulation of miRNAs in extracellular vesicles or exosomes contributes to their stability. Exosomes are constantly secreted by many cells and size of about 30 to 150 nm. Enveloping miRNAs exosomes can release them for cellular communication. The induced transfer of miRNAs by exosomes is a novel process of genetic exchange between cells. Many studies have shown that along with non-exosomal miRNAs, different types of exosomal miRNAs derived from the serum and follicular fluid can play an essential role in PCOS pathogenesis. These miRNAs are involved in follicular development and various functions in granulosa cells, apoptosis, cell proliferation, and follicular atresia. The present study aimed to comprehensively review the evidence on miRNAs and their affected pathways under both non-exosomal and exosomal circumstances, primarily focusing on the pathogenesis of PCOS.

High expression of miR-22-3p in chicken hierarchical follicles promotes granulosa cell proliferation, steroidogenesis, and lipid metabolism via PTEN/PI3K/Akt/mTOR signaling pathway

MicroRNAs (miRNAs) are a class of RNA macromolecules that play regulatory roles in follicle development by inhibiting protein translation through binding to the 3'UTR of its target genes. Granulosa cell (GC) proliferation, steroidogenesis, and lipid metabolism have indispensable effect during folliculogenesis. In this study, we found that miR-22-3p was highly expressed in the hierarchical follicles of the chickens, which indicated that it may be involved in follicle development. The results obtained suggested that miR-22-3p promoted proliferation, hormone secretion (progesterone and estrogen), and the content of lipid droplets (LDs) in the chicken primary GC. The results from the bioinformatics analysis, luciferase reporter assay, qRT-PCR, and Western blotting, confirmed that PTEN was directly targeted to miR-22-3p. Subsequently, it was revealed that PTEN inhibited proliferation, hormone secretion, and the content of LDs in GC. Therefore, this study showed that miR-22-3p could activate PI3K/Akt/mTOR pathway via targeting PTEN. Taken together, the findings from this study indicated that miR-22-3p was highly expressed in the hierarchical follicles of chickens, which promotes GC proliferation, steroidogenesis, and lipid metabolism by repressing PTEN to activate PI3K/AKT/mTOR pathway.

Exosomal microRNAs in tubal fluid may be involved in damage to tubal reproductive function associated with tubal endometriosis

RESEARCH QUESTION

What is the effect of tubal endometriosis on tubal epithelial ultrastructure and is there a differential expression of exosomal microRNAs (miRNAs) in tubal fluid which may affect tubal infertility?

DESIGN

Human fallopian tube epithelium and tubal fluid samples were obtained from patients with and without tubal endometriosis. Scanning electron microscopy and transmission electron microscopy were used to assess ultrastructural changes. Exosomal miRNAs in tubal fluid were extracted for microarray.

RESULTS

Epithelial damage was visualized in the tubal endometriosis group using electron microscopy. The number of organelles decreased (P = 0.0314), and organelle structure was destroyed. A total of 14 differentially expressed exosomal miRNAs were detected in tubal fluid (fold change >2 and P < 0.05). Four miRNAs (miR-1273f, miR-5699-5p, miR-6087 and miR-6747-5p) were validated by quantitative real-time polymerase chain reaction. Bioinformatic analysis showed that most of the target genes participated in embryo transport, regulation of cell communication, anatomical structure morphogenesis and immune system processes.

CONCLUSIONS

Tubal endometriosis results in damage to the tubal epithelial ultrastructure in human specimens and the presence of differentially expressed exosomal miRNAs in tubal liquid. These findings help to clarify the pathogenesis of tubal endometriosis-associated infertility and the mechanisms driving tubal epithelial ultrastructure damage in tubal endometriosis.

MicroRNA profiling reveals effects of Erzhi Tiangui granules on kidney deficiency diminished ovarian reserve: A randomized trial

BACKGROUND

Diminished ovarian reserve (DOR) is a danger signal of reduced fertility. The clinical incidence is increasing yearly, exhibiting a gradual low-age trend. Traditional Chinese medicine theory suggests that kidney deficiency is the basic pathogenesis. Erzhi Tiangui granules (ETG), a kidney-tonifying prescription, have been clinically shown to improve ovarian reserve function. The purpose of this study was to investigate the microRNA (miRNA) markers of kidney deficiency DOR and the potential mechanism of ETG on in vitro fertilization outcomes in DOR patients.

METHODS

Experiment 1: Granulosa cells from 5 normal ovarian reserves and 5 kidney deficiency DOR patients were subjected to miRNA sequencing. Experiment 2: Eighty DOR patients were randomly divided into treatment and control groups (40 subjects each), then treated with ETG and placebo, respectively. granulosa cells were collected and subjected to quantitative polymerase chain reaction for analyzing the expression of specific miRNA found in experiment 1. We also compared fertilization rates, high-quality embryos, and clinical pregnancy rates between the 2 groups.

RESULTS

miRNA sequencing revealed differential expression of 81 miRNAs, of which 39 were downregulated, specially miR-214-3p and miR-193a-5p, whereas 42 were upregulated, specially let-7e-5p and miR-140-3p. In the second experiment, we found that miR-214-3p was significantly upregulated whereas let-7e-5p and miR-140-3p were significantly downregulated in the treatment group, relative to the control group (P < .05). Patients in the ETG treatment group exhibited a significantly higher fertilization rate than those in the control group (P < .05).

CONCLUSION

ETG significantly increased fertilization rates in DOR patients with kidney deficiency syndrome and affected the expression of miR-214-3p, let-7e-5p, and miR-140-3p, the potential biomarkers.

Role of miRNAs interference on ovarian functions and premature ovarian failure

Premature ovarian failure is a to some extent unknown and intricate problem with diverse causes and clinical manifestations. The lack of ovarian sex hormones presumably is effective in the occurrence of ovarian failure. Our progress in this field has been very little despite undertaken scientific research endeavors; scholars still are trying to understand the explanation of this dilemmatic medical condition. In contrast, the practice of clinical medicine has made meaningful strides in providing assurance to the women with premature ovarian insufficiency that their quality of life as well as long-term health can be optimized through timely intervention. Very recently Scientists have investigated the regulating effects of small RNA molecules on steroidogenesis apoptosis, ovulation, gonadal, and corpus luteum development of ovaries. In this literature review, we tried to talk over the mechanisms of miRNAs in regulating gene expression after transcription in the ovary. Video abstract.

Up-regulation of miR-133a-3p promotes ovary insulin resistance on granulosa cells of obese PCOS patients via inhibiting PI3K/AKT signaling

Background

MicroRNAs are a type of non-coding single-stranded RNA, which is involved in the regulation of ovary insulin resistance (IR). This study aims to explore the underlying mechanisms of miR-133a-3p regulating ovary IR in obese polycystic ovary syndrome (PCOS).

Methods

Granulosa cells (GCs) were extracted from follicular fluids of PCOS patients (obese PCOS group and non-obese PCOS group) and healthy women (control group). The expression of miR-133a-3p in GCs was detected by qRT-PCR. The targets and pathways of miR-133a-3p were predicted by bioinformatics analyses. The protein levels of PI3K, p-AKT, GLUT4, p-GSK-3β, and p-FOXO1 were measured by Western blotting.

Results

MiR-133a-3p was highly expressed in GCs from PCOS patients, especially in obese PCOS patients. The protein levels of PI3K and p-AKT was downregulated in GCs from PCOS patients. There were 11 target genes of miR-133a-3p enriching in PI3K/AKT signaling pathway. miR-133a-3p mimic downregulated the expression of PI3K, p-AKT, and GLUT4, and upregulated the protein levels of p-GSK-3β and p-FOXO1. miR-133a-3p inhibitor presented the opposite effect of miR-133a-3p mimic.

Conclusion

MiR-133a-3p promotes ovary IR on GCs of obese PCOS patients via inhibiting PI3K/AKT signaling pathway. This study lays a foundation for further research on the mechanism of ovary IR in obese PCOS patients.

MicroRNA-7a2 Contributes to Estrogen Synthesis and Is Modulated by FSH via the JNK Signaling Pathway in Ovarian Granulosa Cells

MicroRNA-7a2 (miR-7a2) plays fundamental roles in the female reproductive axis, and estrogen is indispensable for maintaining ovary function. However, the interaction between miR-7a2 and ovarian function is unclear. The present study aimed to determine whether and how miR-7a2 functions in estrogen synthesis. Firstly, the results verified that miR-7a was highly expressed in ovarian granulosa cells. The knockout (KO) of miR-7a2 caused infertility and abnormal ovarian function in mice. Concomitantly, the Cyp19a1 expression and estrogen synthesis were significantly inhibited, which was validated in primary granulosa cells. The mice transplanted with miR-7a2 KO ovaries showed similar results; however, estrogen supplementation reversed infertility. In the in vitro experiment, follicle-stimulating hormone (FSH) significantly improved the expression of miR-7a and Cyp19a1 and the synthesis of estrogen. However, the miR-7a2 KO markedly reversed the function of FSH. Also, FSH upregulated miR-7a by activating the (c-Jun N-terminal kinase) JNK signaling pathway. In addition, Golgi apparatus protein 1 (Glg1) was shown to be the target gene of miR-7a2. These findings indicated that miR-7a2 is essential for ovarian functions with respect to estrogen synthesis through the targeted inhibition of the expression of Glg1 and then promoting Cyp19a1 expression; the physiological process was positively regulated by FSH via the JNK signaling pathway in granulosa cells.

An integrated in silico analysis highlighted angiogenesis regulating miRNA-mRNA network in PCOS pathophysiology

Background

Polycystic ovary syndrome (PCOS) is a heterogeneous endocrinopathy and a leading cause of anovulatory infertility. Angiogenesis is vital for ovarian folliculogenesis. The expression of angiogenesis-associated genes/proteins is altered in the ovary of PCOS women. However, information on microRNAs (miRNAs) regulating their expression is limited. This study aims to identify dysregulated angiogenesis-related genes in the ovary of women with PCOS, to identify miRNAs regulating them, and to construct a miRNA-mRNA network associated with angiogenesis.

Methods

A comprehensive literature search and reanalysis of seven ovarian GEO microarray datasets were performed to identify differentially expressed angiogenesis-related genes in PCOS. These target genes were used to predict their regulating miRNAs by querying miRNA databases and their expression in the ovary was verified. Panther and STRING database were used for functional enrichment. Gene expression of shortlisted miRNAs was studied in granulosa cells using digital droplet PCR.

Results

The miRNAs expressed in the ovary and potentially targeting dysregulated angiogenesis-related genes in PCOS were identified and those enriched in angiogenesis-related pathways, like VEGF, FGF, PI3K/Akt, Notch signaling, and ECM interaction were shortlisted. Analysis showed PI3K/Akt signaling was the most enriched pathway. MiR-218-5p, miR-214-3p, miR-20a-5p, and miR-140-3p associated with the PI3K/Akt pathway were found to be up-regulated in granulosa cells of women with PCOS.

Conclusions

By in silico analysis, we identified crucial dysregulated angiogenesis-related genes, the miRNA-mRNA interactions, and signaling pathways involved in impaired follicular angiogenesis in PCOS. This work provides a novel insight into the mechanism of aberrant ovarian angiogenesis contributing to PCOS pathophysiology.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10815-022-02396-1.

Transcriptome Analyses Identify Potential Key microRNAs and Their Target Genes Contributing to Ovarian Reserve

Female endocrinological symptoms, such as premature ovarian inefficiency (POI) are caused by diminished ovarian reserve and chemotherapy. The etiology of POI remains unknown, but this can lead to infertility. This has accelerated the search for master regulator genes or other molecules that contribute as enhancers or silencers. The impact of regulatory microRNAs (miRNAs) on POI has gained attention; however, their regulatory function in this condition is not well known. RNA sequencing was performed at four stages, 2-(2 W), 6-(6 W), 15-(15 W), and 20-(20 W) weeks, on ovarian tissue samples and 5058 differentially expressed genes (DEGs) were identified. Gene expression and enrichment were analyzed based on the gene ontology and KEGG databases, and their association with other proteins was assessed using the STRING database. Gene set enrichment analysis was performed to identify the key target genes. The DEGs were most highly enriched in 6 W and 15 W groups. Figla, GDF9, Nobox, and Pou51 were significantly in-creased at 2 W compared with levels at 6 W and 20 W, whereas the expression of Foxo1, Inha, and Taf4b was significantly de-creased at 20 W. Ccnd2 and Igf1 expression was maintained at similar levels in each stage. In total, 27 genes were upregulated and 26 genes interacted with miRNAs; moreover, stage-specific upregulated and downregulated interactions were demonstrated. Increased and decreased miRNAs were identified at each stage in the ovaries. The constitutively expressed genes, Ccnd2 and Igf1, were identified as the major targets of many miRNAs (p < 0.05), and Fshr and Foxo3 interacted with miRNAs, namely mmu-miR-670-3p and mmu-miR-153-3p. miR-26a-5p interacted with Piwil2, and its target genes were downregulated in the 20 W mouse ovary. In this study, we aimed to identify key miRNAs and their target genes encompassing the reproductive span of mouse ovaries using mRNA and miRNA sequencing. These results indicated that gene sets are regulated in the reproductive stage-specific manner via interaction with miRNAs. Furthermore, consistent expression of Ccnd2 and Igf1 is considered crucial for the ovarian reserve and is regulated by many interactive miRNAs.

New biomarkers in peripheral blood of patients with ovarian cancer: high expression levels of miR-16-5p, miR-17-5p, and miR-638

OBJECTIVES

Ovarian cancer is one of the most fatal gynecologic malignities. miR-16-5p, miR-17-5p, and miR-638 genes were found to have been associated with ovarian cancer in accordance with the data obtained from the previous microarray research performed by Tuncer et al. (J Ovarian Res 13(1):99, 2020). The expression levels of these miRNAs in the peripheral blood samples of 142 ovarian cancer patients, and 97 healthy controls were investigated for performing the validation, and to identify whether these genes were the possible biomarkers to be used in the early diagnosis of high-risk ovarian cancer patients, and in the prognosis of patients.

METHODS

The miRNA expression analysis was performed using the miRNA-specific cDNA synthesis, and real-time PCR methods following the RNA isolation from the peripheral blood lymphocytes.

RESULTS

miR-16-5p, miR-17-5p, and miR-638 miRNA gene expression levels were found to have twofold higher expression levels in patient groups compared with the gene expression levels in healthy controls, and were statistically significant (p < 0.05). In addition, the comparison of the miRNA expression levels with the clinical data of patients showed that there was a significant difference with smoking history and the increased expression level of miR-17-5 (p: 0.007). There was a significant difference between the increased expression level of miR-638 with the locally advanced stage, and abdominal/pelvic metastatic patients (p: 0.03).

CONCLUSIONS

The obtained data suggest that miR-16-5p, miR-17-5p, and miR-638 molecules might be the noninvasive biomarkers in identifying the ovarian cancer. However, the investigation and monitoring of the changeability of these biomarkers in benign ovarian diseases, and during the treatment must be performed in future studies for identifying the accurate diagnostic, and prognostic features of miRNAs.

An Insight on the Role of Altered Function and Expression of Exosomes and MicroRNAs in Female Reproductive Diseases

Exosomes are small bilayer-lipid membrane vesicles secreted by living cells that are able to transfer regulatory molecules and genetic information from one cell to another. These vesicles are enriched with several nucleic acids including mRNAs, microRNAs (miRNAs), other non-coding RNAs, as well as proteins and lipids. Alterations in the exosomal content and functions are observed in numerous reproductive diseases in both animals and human cases. MicroRNAs, a class of small endogenous RNA molecules, can negatively regulate gene expression at the post-transcription level. Aberrant microRNA expression has been reported in multiple human reproductive diseases such as polycystic ovary syndrome, preeclampsia, uterine leiomyomata, ovarian cancer, endometriosis, and Asherman's syndrome. This study focuses to review recent research on alterations of microRNA expression and the role of exosomes in female reproductive diseases. It has been demonstrated that exosomes may be a potential therapeutic approach in various female reproductive diseases. In addition, changes in expression of microRNAs act as molecular biomarkers for diagnosis of several reproductive diseases in women, and regulation of their expression can potentially reduce infertility.

Genome-wide transcriptome profiling uncovers differential miRNAs and lncRNAs in ovaries of Hu sheep at different developmental stages

Ovary development is an important determinant of the procreative capacity of female animals. Here, we performed genome-wide sequencing of long non-coding RNAs (lncRNAs) and mRNAs on ovaries of 1, 3 and 8 months old Hu sheep to assess their expression profiles and roles in ovarian development. We identified 37,309 lncRNAs, 45,404 messenger RNAs (mRNAs) and 330 novel micro RNAs (miRNAs) from the transcriptomic analysis. Six thousand, seven hundred and sixteen (6716) mRNAs and 1972 lncRNAs were significantly and differentially expressed in ovaries of 1 month and 3 months old Hu sheep (H1 vs H3). These mRNAs and target genes of lncRNAs were primarily enriched in the TGF-β and PI3K-Akt signalling pathways which are closely associated with ovarian follicular development and steroid hormone biosynthesis regulation. We identified MSTRG.162061.1, MSTRG.222844.7, MSTRG.335777.1, MSTRG.334059.16, MSTRG.188947.6 and MSTRG.24344.3 as vital genes in ovary development by regulating CTNNB1, CCNA2, CDK2, CDC20, CDK1 and EGFR expressions. A total of 2903 mRNAs and 636 lncRNAs were differentially expressed in 3 and 8 months old ovaries of Hu sheep (H3 vs H8); and were predominantly enriched in PI3K-Akt, progesterone-mediated oocyte maturation, estrogen metabolism, ovulation from the ovarian follicle and oogenesis pathways. These lncRNAs were also found to regulate FGF7, PRLR, PTK2, AMH and INHBA expressions during follicular development. Our result indicates the identified genes participate in the development of the final stages of follicles and ovary development in Hu sheep.

MicroRNA-Mediated Gene Regulatory Mechanisms in Mammalian Female Reproductive Health

Mammalian reproductive health affects the entire reproductive cycle starting with the ovarian function through implantation and fetal growth. Various environmental and physiological factors contribute to disturbed reproductive health status leading to infertility problems in mammalian species. In the last couple of decades a significant number of studies have been conducted to investigate the transcriptome of reproductive tissues and organs in relation to the various reproductive health issues including endometritis, polycystic ovarian syndrome (PCOS), intrauterine growth restriction (IUGR), preeclampsia, and various age-associated reproductive disorders. Among others, the post-transcriptional regulation of genes by small noncoding miRNAs contributes to the observed transcriptome dysregulation associated with reproductive pathophysiological conditions. MicroRNAs as a class of non-coding RNAs are also known to be involved in various pathophysiological conditions either in cellular cytoplasm or they can be released to the extracellular fluid via membrane-bounded extracellular vesicles and proteins. The present review summarizes the cellular and extracellular miRNAs and their association with the etiology of major reproductive pathologies including PCOS, endometritis, IUGR and age-associated disorders in various mammalian species.

Exosomes: Emerging biomarkers and targets in folliculogenesis and endometriosis

An appropriate connection of the cells in the ovary follicles is vital for a healthy ovule maturation and fertilization, and also for endometrium preparation for implantation that can cause endometriosis. Cellular communication within the follicle and endometrial epithelium involve many signaling molecules. Recent studies indicate that cellular communication can be enclosed by secretion and absorption of small membrane carriers which are named extracellular vesicles including exosomes and microvesicles. Understanding and defining these EVs (Extracellular vesicles) population are important for future studies and clinical translation. Here, we describe the various important cargos which are carried by exosomes during folliculogenesis and endometriosis. Additionally, the current knowledge of exosomes and their cargo within the FF (Follicular fluid) during the folliculogenesis and also in the intrauterine cavity which are involved in endometriosis lesions have also been summarized. Considering the potential importance of this form of the cell to cell communication in the reproductive system, the vital issues under discussion lead to a new insight in this rapidly expanding field and it may be an interesting approach for diagnostic, prognostic and especially therapeutic strategies in the field of infertility and assisted reproductive technology (ART).

miR-431 regulates granulosa cell function through the IRS2/PI3K/AKT signaling pathway

MicroRNAs (miRNAs) regulate the functions of granulosa cells by interacting with their target mRNAs. Insulin receptor substrate 2 (IRS2) is one of the targets of miR-431 and can be regulated by ovarian hormones. However, the role of miR-431 and the associated signal transduction pathway in ovarian development has not been studied previously. In this study, we first analyzed the expression of miR-431 and IRS2 following stimulation with pregnant mare serum gonadotropin (PMSG) during the estrous cycle or different stages of ovarian development in mice. Subsequently, we investigated the role, function, and signaling pathway of miR-431 in the human granulosa cell line, COV434. The results showed that follicle stimulating hormone (FSH) gradually decreased miR-431 levels, induced IRS2, and promoted pAKT expression. Moreover, miR-431 overexpression and IRS2 knockdown attenuated AKT activation, inhibited cell proliferation, and decreased estradiol (E2) and progesterone (P4) synthesis. Further, luciferase reporter assay demonstrated that IRS2 was a direct target of miR-431. In conclusion, this study demonstrated that miR-431 regulates granulosa cell function through the IRS2/PI3K/AKT signaling pathway.

The role of miRNAs in regulating adrenal and gonadal steroidogenesis

miRNAs are endogenous noncoding single-stranded small RNAs of ~22 nucleotides in length that post-transcriptionally repress the expression of their various target genes. They contribute to the regulation of a variety of physiologic processes including embryonic development, differentiation and proliferation, apoptosis, metabolism, hemostasis and inflammation. In addition, aberrant miRNA expression is implicated in the pathogenesis of numerous diseases including cancer, hepatitis, cardiovascular diseases and metabolic diseases. Steroid hormones regulate virtually every aspect of metabolism, and acute and chronic steroid hormone biosynthesis is primarily regulated by tissue-specific trophic hormones involving transcriptional and translational events. In addition, it is becoming increasingly clear that steroidogenic pathways are also subject to post-transcriptional and post-translational regulations including processes such as phosphorylation/dephosphorylation, protein‒protein interactions and regulation by specific miRNAs, although the latter is in its infancy state. Here, we summarize the recent advances in miRNA-mediated regulation of steroidogenesis with emphasis on adrenal and gonadal steroidogenesis.

MicroRNA-181a promotes follicular granulosa cell apoptosis via sphingosine-1-phosphate receptor 1 expression downregulation†

Oxidative stress induces granulosa cell (GC) apoptosis and subsequent follicular atresia. Since our previous studies indicate that microRNA-181a (miR-181a) expression is increased in GCs undergoing apoptosis, the present study was designed to define the relationship between exposure to oxidative stressors in GCs and changes in miR-181a expression and function. To achieve this, we employed an H2O2-induced in vitro model and a 3-nitropropionic acid-induced in vivo model of ovarian oxidative stress. We demonstrated that in vitro miR-181a overexpression promoted GC apoptosis in a dose-dependent manner; sphingosine-1-phosphate (S1P) significantly reversed both H2O2-induced and miR-181a-induced apoptosis in GCs. Moreover, we identified sphingosine-1-phosphate receptor 1 (S1PR1), a critical receptor of S1P, as a novel target of miR-181a in GCs. MicroRNA-181a induced GC apoptosis by repressing S1PR1 expression in vitro. Importantly, increased miR-181a expression and decreased S1PR1 expression were detected in the in vivo ovarian oxidative stress model by Western blot analysis and immunohistochemistry. Furthermore, we found similar expression patterns of miR-181a and S1PR1 in GCs from patients with premature ovarian insufficiency. In conclusion, our results suggest that miR-181a directly suppresses expression of S1PR1, which has critical roles in mediating oxidative stress-induced GC apoptosis both in vitro and in vivo.

MicroRNA profiling and identification of let-7a as a target to prevent chemotherapy-induced primordial follicles apoptosis in mouse ovaries

Cancer treatments as cyclophosphamide and its active metabolites are highly gonadotoxic leading to follicle apoptosis and depletion. Considering the risk of subsequent infertility, fertility preservation is recommended. Beside the germ cells and gametes cryopreservation options, ovarian pharmacological protection during treatment appears to be very attractive. Meanwhile, the advances in the field of oncology have brought microRNAs into spotlight as a potential feature of cancer treatment. Herein, we investigated miRNAs expressions in response to chemotherapy using postnatal-day-3 (PND3) mouse ovaries. Our results revealed that several miRNAs are differently expressed during chemotherapy exposure. Amongst them, let-7a was the most profoundly downregulated and targets genes involved in crucial cellular processes including apoptosis. Thus we developed a liposome-based system to deliver the let-7a mimic in whole PND3 ovaries in vitro. We showed that let-7a mimic prevented the upregulation of genes involved in cell death and reduced the chemotherapy-induced ovarian apoptosis, suggesting that it can be an interesting target to preserve ovarian function. However, its impact on subsequent follicular development has to be further elucidated in vivo using an appropriate delivery system. In this study, we demonstrated that miRNA replacement approaches can be a useful tool to reduce chemotherapy-induced ovarian damage in the future.

A unique insight into the MiRNA profile during genital chlamydial infection

Background

Genital C. trachomatis infection may cause pelvic inflammatory disease (PID) that can lead to tubal factor infertility (TFI). Understanding the pathogenesis of chlamydial complications including the pathophysiological processes within the female host genital tract is important in preventing adverse pathology. MicroRNAs regulate several pathophysiological processes of infectious and non-infectious etiologies. In this study, we tested the hypothesis that the miRNA profile of single and repeat genital chlamydial infections will be different and that these differences will be time dependent. Thus, we analyzed and compared differentially expressed mice genital tract miRNAs after single and repeat chlamydia infections using a C. muridarum mouse model. Mice were sacrificed and their genital tract tissues were collected at 1, 2, 4, and 8 weeks after a single and repeat chlamydia infections. Histopathology, and miRNA sequencing were performed.

Results

Histopathology presentation showed that the oviduct and uterus of reinfected mice were more inflamed, distended and dilated compared to mice infected once. The miRNAs expression profile was different in the reproductive tissues after a reinfection, with a greater number of miRNAs expressed after reinfection. Also, the number of miRNAs expressed each week after chlamydia infection and reinfection varied, with weeks eight and one having the highest number of differentially expressed miRNAs for chlamydia infection and reinfection respectively. Ten miRNAs; mmu-miR-378b, mmu-miR-204-5p, mmu-miR-151-5p, mmu-miR-142-3p, mmu-miR-128-3p, mmu-miR-335-3p, mmu-miR-195a-3p, mmu-miR-142-5p, mmu-miR-106a-5p and mmu-miR-92a-3p were common in both primary chlamydia infection and reinfection. Pathway analysis showed that, amongst other functions, the differentially regulated miRNAs control pathways involved in cellular and tissue development, disease conditions and toxicity.

Conclusions

This study provides insights into the changes in miRNA expression over time after chlamydia infection and reinfection, as well as the pathways they regulate to determine pathological outcomes. The miRNAs networks generated in our study shows that there are differences in the focus molecules involved in significant biological functions in chlamydia infection and reinfection, implying that chlamydial pathogenesis occurs differently for each type of infection and that this could be important when determining treatments regime and disease outcome. The study underscores the crucial role of host factors in chlamydia pathogenesis.

Electronic supplementary material

The online version of this article (10.1186/s12864-019-5495-6) contains supplementary material, which is available to authorized users.

MicroRNAs in ovarian follicular atresia and granulosa cell apoptosis

MicroRNAs (miRNAs) are short, noncoding RNAs that posttranscriptionally regulate gene expression. In the past decade, studies on miRNAs in ovaries have revealed the key roles of miRNAs in ovarian development and function. In this review, we first introduce the development of follicular atresia research and then summarize genome-wide studies on the ovarian miRNA profiles of different mammalian species. Differentially expressed miRNA profiles during atresia and other biological processes are herein compared. In addition, current knowledge on confirmed functional miRNAs during the follicular atresia process, which is mostly indicated by granulosa cell (GC) apoptosis, is presented. The main miRNA families and clusters, including the let-7 family, miR-23-27-24 cluster, miR-183-96-182 cluster and miR-17-92 cluster, and related pathways that are involved in follicular atresia are thoroughly summarized. A deep understanding of the roles of miRNA networks will not only help elucidate the mechanisms of GC apoptosis, follicular development, atresia and their disorders but also offer new diagnostic and treatment strategies for infertility and other ovarian dysfunctions.

Anabolic Androgenic Steroids: Searching New Molecular Biomarkers

Even if anabolic androgenic steroid (AAS) abuse is clearly associated with a wide spectrum of collateral effects, adolescents and athletes frequently use a large group of synthetic derivatives of testosterone, both for aesthetic uses and for improving performance. Over the last few years, the development of MicroRNA (miRNA) technologies has become an essential part of research projects and their role as potential molecular biomarkers is being investigated by the scientific community. The circulating miRNAs detection as a diagnostic or prognostic tool for the diagnosis and treatment of several diseases is very useful, because with a minimal quantity of sample (peripheral blood), miRNAs are very sensitive. Even more, miRNAs remain stable both at room temperature and during freeze-thaw cycles. These characteristics highlight the important role of miRNAs in the near future as new tools for anti-doping. The article provides a systematic review and meta-analysis on the role of miRNAs as new potential molecular biomarkers of AAS use/abuse. Particularly, this paper analyzed the “miRNA signature” use as biomarkers for health disorders, focusing on the organ damages which are related to ASS use/abuse. Moreover, this review aims to provide a future prospect for less invasive or non-invasive procedures for the detection of circulating miRNA biomarkers as doping assumption signaling.

Micro-RNAs involved in cellular proliferation have altered expression profiles in granulosa of young women with diminished ovarian reserve

PURPOSE

The study aims to determine differences in micro-RNA (miRNA) expression in granulosa (GC) and cumulus cells (CC) between young women with diminished ovarian reserve (DOR) or normal ovarian reserve (NOR). Secondary objective was to identify downstream signaling pathways that could ultimately indicate causes of lower developmental competence of oocytes from young women with DOR.

METHODS

The method of the study is prospective cohort study.

RESULTS

Of the miRNA, 125 are differentially expressed in GC between DOR and NOR. Only nine miRNA were different in CC; therefore, we focused analysis on GC. In DOR GC, miR-100-5p, miR-16-5p, miR-30a-3p, and miR-193a-3p were significantly downregulated, while miR-155-5p, miR-192-5p, miR-128-3p, miR-486-5p, miR130a-3p, miR-92a-3p, miR-17-3p, miR-221-3p, and miR-175p were increased. This pattern predicted higher cell proliferation in the DOR GC. The primary pathways include MAPK, Wnt, and TGFbeta.

CONCLUSIONS

The miRNA pattern identified critical functions in cell proliferation and survival associated with DOR. GC in women with DOR seems to respond differently to the LH surge.

Di(2-ethylhexyl) phthalate (DEHP) influences follicular development in mice between the weaning period and maturity by interfering with ovarian development factors and microRNAs

Although studies have shown that di(2-ethylhexyl) phthalate (DEHP) can disrupt ovarian function, few reports have focused on follicular development in mice between the weaning period and maturity, especially with respect to microRNA (miRNA) expression. In this study, 21-day-old ICR mice were administered DEHP at doses of 0, 100, 400, and 1600 mg/(kg d) for 6 weeks by gavage. After DEHP administration, a significant decrease in the expression of follicle development-related factors (including c-kit, kitl, gdf9, and atm) was observed by quantitative real-time PCR (RT-PCR), but no significant difference in the proteins encoded by these genes was observed by Western blot. Bisulfite sequencing suggested that the total methylation percentages of promoter regions of these genes were not notably altered after DEHP exposure. However, RT-PCR revealed a significantly increased expression of ovarian miRNAs (let-7b, miR-17-5p miR-181a, and miR-151), which inhibit follicular granulosa cell proliferation. Overall, this study showed that DEHP administration from weaning to maturity could suppress the mRNA expression of follicular development factors, and this effect was not achieved through changes in the methylation of DNA in CpG islands of development factors. In addition, DEHP was shown to induce miRNAs to inhibit the proliferation of follicular granulosa cells and the anti-apoptosis function of KITL and GDF9 while increasing bax/bcl₂ expression to further promote the apoptosis of granulosa cells.

Non-coding RNAs in the Ovarian Follicle

The mammalian ovarian follicle is the complex reproductive unit comprising germ cell, somatic cells (Cumulus and Granulosa cells), and follicular fluid (FF): paracrine communication among the different cell types through FF ensures the development of a mature oocyte ready for fertilization. This paper is focused on non-coding RNAs in ovarian follicles and their predicted role in the pathways involved in oocyte growth and maturation. We determined the expression profiles of microRNAs in human oocytes and FF by high-throughput analysis and identified 267 microRNAs in FF and 176 in oocytes. Most of these were FF microRNAs, while 9 were oocyte specific. By bioinformatic analysis, independently performed on FF and oocyte microRNAs, we identified the most significant Biological Processes and the pathways regulated by their validated targets. We found many pathways shared between the two compartments and some specific for oocyte microRNAs. Moreover, we found 41 long non-coding RNAs able to interact with oocyte microRNAs and potentially involved in the regulation of folliculogenesis. These data are important in basic reproductive research and could also be useful for clinical applications. In fact, the characterization of non-coding RNAs in ovarian follicles could improve reproductive disease diagnosis, provide biomarkers of oocyte quality in Assisted Reproductive Treatment, and allow the development of therapies for infertility disorders.

Antigen specific immune response in Chlamydia muridarum genital infection is dependent on murine microRNAs-155 and -182

Anti-chlamydial immunity involves efficient presentation of antigens (Ag) to effector cells resulting in Ag-specific immune responses. There is limited information on inherent underlying mechanisms regulating these events. Previous studies from our laboratory have established that select microRNAs (miRs) function as molecular regulators of immunity in Chlamydia muridarum (Cm) genital infection. In this report, we investigated immune cell type-specific miRs, i.e. miR-155 and -182, and the role in Ag-specific immunity. We observed significant up-regulation of miR-155 in C57BL/6 bone marrow derived dendritic cells (BMDC), and miR-182 in splenic Ag-specific CD4+ T-cells. Using mimics and inhibitors, we determined that miR-155 contributed to BMDC activation following Cm infection. Co-cultures of miR-155 over-expressed in BMDC and miR-182 over-expressed in Ag-specific CD4+ T-cells, or miR-155-/- BMDC with miR-182 inhibitor treated Ag-specific CD4+ T-cells, resulted in IFN-γ production comparable to Ag-specific CD4+ T-cells isolated from Cm infected mice. Additionally, miR-182 was significantly up-regulated in intranasally vaccinated mice protected against Cm infection. In vivo depletion of miR-182 resulted in reduction in Ag-specific IFN-γ and genital pathology in Cm infected mice. To the best of our knowledge, this is the first study to report an interaction of miR-155 (in Cm infected DC) and miR-182 (in CD4+ T-cell) resulting in Ag specific immune responses against genital Cm.

Exosome-mediated communication in the ovarian follicle

Cells are able to produce and release different types of vesicles, such as microvesicles and exosomes, in the extracellular microenvironment. According to the scientific community, both microvesicles and exosomes are able to take on and transfer different macromolecules from and to other cells, and in this way, they can influence the recipient cell function. Among the different macromolecule cargos, the most studied are microRNAs. MicroRNAs are a large family of non-coding RNAs involved in the regulation of gene expression. They control every cellular process and their altered regulation is involved in human diseases. Their presence in mammalian follicular fluid has been recently demonstrated, and here, they are enclosed within microvesicles and exosomes or they can also be associated to protein complexes. The presence of microvesicles and exosomes carrying microRNAs in follicular fluid could represent an alternative mechanism of autocrine and paracrine communication inside the ovarian follicle. The outcomes from these studies could be important in basic reproductive research but could also be useful for clinical application. In fact, the characterization of extracellular vesicles in follicular fluid could improve reproductive disease diagnosis and provide biomarkers of oocyte quality in ART (Assisted Reproductive Treatment).

Sperm-borne miRNAs and endo-siRNAs are important for fertilization and preimplantation embryonic development

Although it is believed that mammalian sperm carry small noncoding RNAs (sncRNAs) into oocytes during fertilization, it remains unknown whether these sperm-borne sncRNAs truly have any function during fertilization and preimplantation embryonic development. Germline-specific Dicer and Drosha conditional knockout (cKO) mice produce gametes (i.e. sperm and oocytes) partially deficient in miRNAs and/or endo-siRNAs, thus providing a unique opportunity for testing whether normal sperm (paternal) or oocyte (maternal) miRNA and endo-siRNA contents are required for fertilization and preimplantation development. Using the outcome of intracytoplasmic sperm injection (ICSI) as a readout, we found that sperm with altered miRNA and endo-siRNA profiles could fertilize wild-type (WT) eggs, but embryos derived from these partially sncRNA-deficient sperm displayed a significant reduction in developmental potential, which could be rescued by injecting WT sperm-derived total or small RNAs into ICSI embryos. Disrupted maternal transcript turnover and failure in early zygotic gene activation appeared to associate with the aberrant miRNA profiles in Dicer and Drosha cKO spermatozoa. Overall, our data support a crucial function of paternal miRNAs and/or endo-siRNAs in the control of the transcriptomic homeostasis in fertilized eggs, zygotes and two-cell embryos. Given that supplementation of sperm RNAs enhances both the developmental potential of preimplantation embryos and the live birth rate, it might represent a novel means to improve the success rate of assisted reproductive technologies in fertility clinics.

MicroRNA in ovarian function

The mammalian ovary is a dynamic organ. The coordination of follicle recruitment, selection, and ovulation and the timely development and regression of the corpus luteum are essential for a functional ovary and fertility. Deregulation of any of these processes results in ovarian dysfunction and potential infertility. MicroRNA (miRNA) are short noncoding RNA that regulate developmental processes and time-sensitive functions. The expression of miRNA in the ovary varies with cell type, function, and stage of the estrous cycle. miRNA are involved in the formation of primordial follicles, follicular recruitment and selection, follicular atresia, oocyte-cumulus cell interaction, granulosal cell function, and luteinization. miRNA are differentially expressed in luteal cells at the various stages of the estrous cycle and during maternal recognition of pregnancy, suggesting a role in luteal development, maintenance, and regression. An understanding of the patterns of expression and functions of miRNA in the ovary will lead to novel therapeutics to treat ovarian dysfunction and improve fertility and, potentially, to the development of better contraceptives.