The transcription factor SMAD4 and miR-10b contribute to E2 release and cell apoptosis in ovarian granulosa cells by targeting CYP19A1

Smad4 and FoxH1 potentially interact to regulate cyp19a1a promoter in the ovary of ricefield eel (Monopterus albus)

BACKGROUND

Cyp19a1a is a key enzyme in the pathway that converts androgens into estrogen and is regulated by TGF-β signaling. Smad4 and FoxH1 are downstream effectors of TGF-β signaling and may play important roles in ovarian development in M. albus.

METHODS

We investigated the expression pattern of the Smad4 and FoxH1 using qRT‒PCR and immunofluorescence, then tested the changes of smad4 and foxh1 by qRT‒PCR after ovary incubation with FSH in vitro, and analysed the regulation of cyp19a1a transcription by Smad4 and FoxH1 by dual-luciferase reporter assays.

RESULTS

We found that Smad4 encoded a putative protein of 449 amino acids and harbored the three conserved domains typical of this protein family. Smad4 and foxh1 exhibited similar expression patterns during ovarian development and after FSH incubation, with Pearson's coefficients of 0.873 and 0.63-0.81, respectively. Furthermore, Smad4, FoxH1 and Cyp19a1a colocalized in the granulosa cells and theca cells of ovaries during the mid-to-late vitellogenic stage. Smad4 repressed cyp19a1a activity via SBE1 (- 1372/-1364) and SBE2 (- 415/-407) in the cyp19a1a promoter, whereas mutating SBE1 or SBE2 restored cyp19a1a promoter activity. Co-overexpression of Smad4 and FoxH1 significantly reduced cyp19a1a promoter activity.

CONCLUSIONS

This study provides new insights into the potential functions of transcription factors Smad4 and FoxH1 in ovarian development and the transcriptional regulation mechanism of cyp19a1a in M. albus, which will reveal Smad4/FoxH1-mediated TGF-β signaling in reproduction and the regulation of the cyp19a1a. Aromatase, encoded by cyp19a1a, is involved in ovarian development and plays an important role in the quality of eggs, as well the sex ratio, of the teleost fish, M. albus. The research on the transcriptional regulation of cyp19a1a has contributed to the understanding of its role in ovarian development. In previous study, it was shown that FoxH1 inhibits cyp19a1a transcription. In the present study, Smad4 was confirmed as a cyp19a1a transcriptional repressor and Smad4 may also coordinate with FoxH1 to repress cyp19a1a transcription. At present, we provide a new perspective for the transcriptional regulation of cyp19a1a by transcription factors Smad4 and FoxH1 in teleost fish ovary. In the future, the regulatory networks of Smad4 and FoxH1 will be further studied and the gene editing technology will be applied to screen specific regulatory factors of cyp191a1a gene, so as to alter the female cycle and modulate the sex ratio of the eggs production.

miR-6881-3p contributes to diminished ovarian reserve by regulating granulosa cell apoptosis by targeting SMAD4

BACKGROUND

In our previous investigation, we revealed a significant increase in the expression of microRNA-6881-3p (miR-6881-3p) in follicular fluid granulosa cells (GCs) from women with diminished ovarian reserve (DOR) compared to those with normal ovarian reserve (NOR). However, the role of miR-6881-3p in the development of DOR remains poorly understood.

OBJECTIVE

This study aimed to elucidate the involvement of miR-6881-3p in the regulation of granulosa cells (GCs) function and the pathogenesis of DOR.

MATERIALS AND METHODS

Initially, we assessed the expression levels of miR-6881-3p in GCs obtained from human follicular fluid in both NOR and DOR cases and explored the correlation between miR-6881-3p expression and clinical outcomes in assisted reproduction technology (ART). Bioinformatic predictions and dual-luciferase reporter assays were employed to identify the target gene of miR-6881-3p. Manipulation of miR-6881-3p expression was achieved through the transfection of KGN cells with miR-6881-3p mimics, inhibitor, and miRNA negative control (NC). Following transfection, we assessed granulosa cell apoptosis and cell cycle progression via flow cytometry and quantified target gene expression through quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot (WB) analysis. Finally, we examined the correlation between target gene expression levels in GCs from NOR and DOR patients and their association with ART outcomes.

RESULTS

Our findings revealed elevated miR-6881-3p levels in GCs from DOR patients, which negatively correlated with ovarian reserve function and ART outcomes. We identified a direct binding interaction between miR-6881-3p and the 3'-untranslated region of the SMAD4. Transfection with miR-6881-3p mimics induced apoptosis in KGN cell. Furthermore, miR-6881-3p expression negatively correlated with both mRNA and protein levels of the SMAD4. The mRNA and protein levels of SMAD4 were notably reduced in GCs from DOR patients, and SMAD4 mRNA expression positively correlated with ART outcomes. In addition, the mRNA levels of FSHR, CYP11A1 were notably reduced after transfection with miR-6881-3p mimics in KGN cell, while LHCGR notably increased. The mRNA and protein levels of FSHR, CYP11A1 were notably reduced in GCs from DOR patients, while LHCGR notably increased.

CONCLUSION

This study underscores the role of miR-6881-3p in directly targeting SMAD4 mRNA, subsequently diminishing granulosa cell viability and promoting apoptosis, and may affect steroid hormone regulation and gonadotropin signal reception in GCs. These findings contribute to our understanding of the pathogenesis of DOR.

Effects of environmentally relevant concentrations of niclosamide on lipid metabolism and steroid hormone synthesis in adult female zebrafish

Niclosamide (NIC) is a commonly used molluscicide that reportedly disrupts the endocrine system and may lead to lipid metabolism disorders. However, few studies have investigated the mechanism by which NIC affects the endocrine system from the perspective of lipid metabolism. Adult female zebrafish were fed either a normal-fat diet (NFD) or a high-fat diet (HFD) and then exposed for 28 days to environmentally relevant concentrations of NIC. NIC accumulated most in the liver followed by the brain and then the gonads in both feeding conditions. Somatic index changes confirmed that HFD promotes fish growth, and NIC administration inhibits it. Lipid metabolites were decreased by NIC, as were levels of pregnenolone, androstenedione, estrogen, testosterone, and estradiol, suggesting that NIC impacted steroidogenesis. In addition, gene transcription changes related to the hypothalamic-pituitary-gonad-liver (HPGL) axis and altered ovarian histology strongly suggest that environmental relevant concentrations of NIC exposure may disrupt endocrine function. These findings highlighted that NIC exposure at environmentally relevant concentrations elicited endocrine-disruption effects may through impairing of steroid hormone synthesis.

Nuclear lncRNA NORSF reduces E2 release in granulosa cells by sponging the endogenous small activating RNA miR-339

BACKGROUND

Functioning as a competing endogenous RNA (ceRNA) is the main action mechanism of most cytoplasmic lncRNAs. However, it is not known whether this mechanism of action also exists in the nucleus.

RESULTS

We identified four nuclear lncRNAs that are presented in granulosa cells (GCs) and were differentially expressed during sow follicular atresia. Notably, similar to cytoplasmic lncRNAs, these nuclear lncRNAs also sponge miRNAs in the nucleus of GCs through direct interactions. Furthermore, NORSF (non-coding RNA involved in sow fertility), one of the nuclear lncRNA acts as a ceRNA of miR-339. Thereby, it relieves the regulatory effect of miR-339 on CYP19A1 encoding P450arom, a rate-limiting enzyme for E2 synthesis in GCs. Interestingly, miR-339 acts as a saRNA that activates CYP19A1 transcription and enhances E2 release by GCs through altering histone modifications in the promoter by directly binding to the CYP19A1 promoter. Functionally, NORSF inhibited E2 release by GCs via the miR-339 and CYP19A1 axis.

CONCLUSIONS

Our findings highlight an unappreciated mechanism of nuclear lncRNAs and show it acts as a ceRNA, which may be a common lncRNA function in the cytoplasm and nucleus. We also identified a potential endogenous saRNA for improving female fertility and treating female infertility.

Genome-Wide Association Study on Reproductive Traits Using Imputation-Based Whole-Genome Sequence Data in Yorkshire Pigs

Reproductive traits have a key impact on production efficiency in the pig industry. It is necessary to identify the genetic structure of potential genes that influence reproductive traits. In this study, a genome-wide association study (GWAS) based on chip and imputed data of five reproductive traits, namely, total number born (TNB), number born alive (NBA), litter birth weight (LBW), gestation length (GL), and number of weaned (NW), was performed in Yorkshire pigs. In total, 272 of 2844 pigs with reproductive records were genotyped using KPS Porcine Breeding SNP Chips, and then chip data were imputed to sequencing data using two online software programs: the Pig Haplotype Reference Panel (PHARP v2) and Swine Imputation Server (SWIM 1.0). After quality control, we performed GWAS based on chip data and the two different imputation databases by using fixed and random model circulating probability unification (FarmCPU) models. We discovered 71 genome-wide significant SNPs and 25 potential candidate genes (e.g., SMAD4, RPS6KA2, CAMK2A, NDST1, and ADCY5). Functional enrichment analysis revealed that these genes are mainly enriched in the calcium signaling pathway, ovarian steroidogenesis, and GnRH signaling pathways. In conclusion, our results help to clarify the genetic basis of porcine reproductive traits and provide molecular markers for genomic selection in pig breeding.

Role and mechanism of miR-335-5p in the pathogenesis and treatment of polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is a common endocrine disorder of unknown etiology that occurs in women of reproductive age. Despite being considered to affect up to one-fifth of women in this cohort, the condition lacks generally accepted diagnostic biomarkers and options for targeted therapy. Hereby, we analyzed the diagnostic, therapeutic, and functional potential of a recently discovered miR-335-5p that was observed to be reduced in the follicular fluid (FF) of PCOS patients as compared with healthy women. We found miR-335-5p to be significantly decreased in the serum and FF samples of PCOS patients (n = 40) vs healthy women (n = 30), as well as in primary human granulosa cells (hGCs), and in 3 different hormonally induced PCOS-like murine models vs. wild-type (WT) mice. The level of circulating miR-335-5p was found to significantly correlate with the impaired endocrine and clinical features associated with PCOS in human patients. Ovarian intrabursal injection of the miR-335-5p antagomir in WT mice ovaries induced a PCOS-like reproductive phenotype. Treatment with the miR-335-5p agomir rescued the dihydrotestosterone-induced PCOS-phenotype in mice, thereby providing a functional link between miR-335-5p and PCOS. We identified SP1 as a miR-335-5p target gene by using the dual-luciferase reporter assay. Both the luciferase reporter assay and chromatin immunoprecipitation assay showed that SP1 bound to the promoter region of human CYP19A1 and inhibited its transcription. miR-335-5p increased the production of estradiol via the SP1/CYP19A1 axis in hGCs, thereby suggesting its mechanistic pathway of action. In conclusion, these results provide evidence that miR-335-5p may function as a mediator in the etiopathogenesis of PCOS, as well as has the potential as both a novel diagnostic biomarker and therapeutic target for PCOS.

The Combined Use of Medium- and Short-Chain Fatty Acids Improves the Pregnancy Outcomes of Sows by Enhancing Ovarian Steroidogenesis and Endometrial Receptivity

Fatty acids play important roles in maintaining ovarian steroidogenesis and endometrial receptivity. Porcine primary ovarian granulosa cells (PGCs) and endometrial epithelial cells (PEECs) were treated with or without medium- and short-chain fatty acids (MSFAs) for 24 h. The mRNA abundance of genes was detected by fluorescence quantitative PCR. The hormone levels in the PGCs supernatant and the rate of adhesion of porcine trophoblast cells (pTrs) to PEECs were measured. Sows were fed diets with or without MSFAs supplementation during early gestation. The fecal and vaginal microbiomes were identified using 16S sequencing. Reproductive performance was recorded at parturition. MSFAs increased the mRNA abundance of genes involved in steroidogenesis, luteinization in PGCs and endometrial receptivity in PEECs (p < 0.05). The estrogen level in the PGC supernatant and the rate of adhesion increased (p < 0.05). Dietary supplementation with MSFAs increased serum estrogen levels and the total number of live piglets per litter (p < 0.01). Moreover, MSFAs reduced the fecal Trueperella abundance and vaginal Escherichia-Shigella and Clostridium_sensu_stricto_1 abundance. These data revealed that MSFAs improved pregnancy outcomes in sows by enhancing ovarian steroidogenesis and endometrial receptivity while limiting the abundance of several intestinal and vaginal pathogens at early stages of pregnancy.

Lnc2300 is a cis-acting long noncoding RNA of CYP11A1 in ovarian granulosa cells

The high level of progesterone and 17β-estradiol ratio (P4/E2) in follicular fluid has been considered as a biomarker of follicular atresia. CYP11A1, the crucial gene encoding the rate-limiting enzyme for steroid hormone synthesis, has been reported differently expressed in the ovary during follicular atresia. However, the regulation mechanism of CYP11A1 expression during follicular atresia still remains unclear. Here, we have demonstrated that lnc2300, a novel pig ovary-specific highly expressed cis-acting long noncoding RNA (lncRNA) transcribed from chromosome 7, has the ability to induce the expression of CYP11A1 and inhibit the apoptosis of porcine granulosa cells (GCs). Mechanistically, lnc2300, mainly located in the cytoplasm of porcine GCs, sponges and suppresses the expression of miR-365-3p through acting as a competing endogenous RNA (ceRNA), which further relieves the inhibitory effects of miR-365-3p on the expression of CYP11A1. Besides, CYP11A1 is validated as a direct functional target of miR-365-3p in porcine GCs. Functionally, lnc2300 is an antiapoptotic lncRNA that reduces porcine GC apoptosis by inhibiting the proapoptotic function of miR-365-3p. In summary, our findings reveal a cis-acting regulation mechanism of CYP11A1 through lncRNA, and define a novel signaling pathway, lnc2300/miR-365-3p/CYP11A1 axis, which is involved in the regulation of GC apoptosis and follicular atresia.

Metformin ameliorates polycystic ovary syndrome in a rat model by decreasing excessive autophagy in ovarian granulosa cells via the PI3K/AKT/mTOR pathway

Polycystic ovary syndrome (PCOS) is a common gynecological disease accompanied by a variety of clinical features, including anovulation, hyperandrogenism, and ovarian abnormalities, resulting in infertility. PCOS affects approximately 6%-15% of all reproductive-age women worldwide. Metformin, a popular drug used to treat PCOS in patients, has beneficial effects in reducing hyperandrogenism and inducing ovulation; however, the mechanisms by which metformin ameliorates PCOS are not clear. Hence, we aimed to explore the mechanisms of metformin in treating PCOS. In the present study, we first treated a letrozole-induced PCOS rat model with metformin, detected the pathological recovery of PCOS, and then assessed the effects of metformin on H₂O₂-induced autophagy in ovarian granulosa cells (GCs) by detecting the level of oxidative stress and the expression of autophagy-associated proteins and key proteins in the PI3K/AKT/mTOR pathway. We demonstrated that metformin ameliorated PCOS in a rat model by downregulating autophagy in GCs, and metformin decreased the levels of oxidative stress and autophagy in H₂O₂-induced GCs and affected the PI3K/AKT/mTOR signaling pathway. Taken together, our results indicate that metformin ameliorates PCOS in a rat model by decreasing excessive autophagy in GCs via the PI3K/AKT/mTOR pathway, and this study provides evidence for targeted reduction of excessive autophagy of ovarian granulosa cells and improvement of PCOS.

MiR-31 targets HSD17B14 and FSHR, and miR-20b targets HSD17B14 to affect apoptosis and steroid hormone metabolism of porcine ovarian granulosa cells

Porcine 17-hydroxysteroid dehydrogenase type 14 (HSD17B14) and FSH reporter (FSHR) genes play important roles in the metabolism of steroid hormones and the apoptosis of ovarian granulosa cells (GCs). Our bioinformatics analyses and the dual luciferase reporter assays indicated that porcine miR-20b and miR-31 target the 3'-UTR region of HSD17B14 gene, and miR-31 also targets the 3'-UTR region of FSHR gene. Overexpression of porcine HSD17B14 gene promoted the conversion from estradiol (E2) to estrone (E1) and increased the apoptosis of porcine GCs. Overexpression of miR-20b down-regulated the mRNA and protein expression level of HSD17B14 gene, decreased the concentration of progesterone (P4) and E1, increased E2, as well as reduced apoptosis of GCs. Moreover, overexpression of miR-31 also down-regulated the protein expression level of HSD17B14 gene, decreased the concentration of P4 and E1, and increased E2. However, miR-31 promoted apoptosis of GCs by targeting to the 3'-UTR of porcine FSHR gene. Taken together, we found that both porcine miR-20b and miR-31 target HSD17B14 gene, but miR-31 also targets FSHR gene to regulate the metabolism of steroid hormones and the apoptosis of porcine ovarian GCs. These findings expand the epigenetic regulatory mechanism of porcine miR-31 and miR-20b in ovarian GCs.

NR1D1 targeting CYP19A1 inhibits estrogen synthesis in ovarian granulosa cells

The circadian system performs an important role in mammalian reproduction with significant effects on hormone secretion. Nuclear receptor subfamily 1 group D member 1 (NR1D1) functions as a transcriptional repressor in the circadian system and affects granulosa cells (GCs), but how it regulates estrogen synthesis has not been clarified. We investigated the effect of NR1D1 on estrogen synthesis and found that NR1D1 was highly expressed in GCs, mainly in cell nuclei. Additionally, the expression of NR1D1 and estrogen synthesis key genes CYP19A1, CYP11A1 and StAR showed rhythmic changes in porcine ovarian GCs. Activation of NR1D1 enhances its ability to inhibit the transcriptional activity of CYP19A1 by binding to the RORE on the CYP19A1 promoter, resulting in a decrease in estradiol content. Interference with NR1D1 can eliminate the transcriptional inhibition of CYP19A1 and promote the synthesis of estradiol. The results suggest that the hormone secretion of the ovary itself is also regulated by the biological clock, and any factors that affect the circadian rhythm can affect the endocrine and reproductive performance of sows, so the natural rhythm of sows should be maintained in production.

microRNA-10b promotes the apoptosis of bovine ovarian granulosa cells by targeting plasminogen activator inhibitor-1

Granulosa cells (GCs) are essential somatic cells in the ovaries, and apoptosis of GCs causes follicular atresia. microRNA-10b (miR-10b) is pivotal for cell apoptosis. However, currently, little is known about the role of miR-10b in bovine ovarian GCs (BGCs). In this study, the effect of miR-10b on the apoptosis of BGCs was investigated. Our results showed that the overexpression of miR-10b could increase the apoptosis rate of BGCs, which is associated with the increased expression of Caspase-3 and decreased expression ratio of Bcl-2/Bax (P < 0.05). Furthermore, plasminogen activator inhibitor-1 (PAI-1) was confirmed to be a validated target of miR-10b in BGCs using dual-luciferase reporter analysis, and transfection of miR-10b mimics decreased the expression of PAI-1 (P < 0.05). In addition, overexpression of PAI-1 significantly inhibited BGC apoptosis (P < 0.05), and PAI-1 could alleviate BGC apoptosis induced by miR-10b (P < 0.05). Subsequently, phosphatidylinositol-3-kinase/protein kinase B (PI3K/AKT) was found to be the downstream pathway of PAI-1 by RNA-Seq analysis and verified by Western blot. Finally, a PI3K/AKT inhibitor (Miltefosine) was used to inhibit the PI3K/AKT pathway, which reversed the inhibitory effect of PAI-1 on the apoptosis of BGCs (P < 0.05), and enhanced the promotion effect of miR-10b on the apoptosis of BGCs (P < 0.05). Our results indicated that miR-10b promotes BGC apoptosis by targeting PAI-1 to regulate the PI3K/AKT pathway.

DNA methylation mediated RSPO2 to promote follicular development in mammals

In female mammals, the proliferation, apoptosis, and estradiol-17β (E2) secretion of granulosa cells (GCs) have come to decide the fate of follicles. DNA methylation and RSPO2 gene of Wnt signaling pathway have been reported to involve in the survival of GCs and follicular development. However, the molecular mechanisms for how DNA methylation regulates the expression of RSPO2 and participates in the follicular development are not clear. In this study, we found that the mRNA and protein levels of RSPO2 significantly increased during follicular development, but the DNA methylation level of RSPO2 promoter decreased gradually. Inhibition of DNA methylation or DNMT1 knockdown could decrease the methylation level of CpG island (CGI) in RSPO2 promoter and upregulate the expression level of RSPO2 in porcine GCs. The hypomethylation of -758/-749 and -563/-553 regions in RSPO2 promoter facilitated the occupancy of transcription factor E2F1 and promoted the transcriptional activity of RSPO2. Moreover, RSPO2 promoted the proliferation of GCs with increasing the expression level of PCNA, CDK1, and CCND1 and promoted the E2 secretion of GCs with increasing the expression level of CYP19A1 and HSD17B1 and inhibited the apoptosis of GCs with decreasing the expression level of Caspase3, cleaved Caspase3, cleaved Caspase8, cleaved Caspase9, cleaved PARP, and BAX. In addition, RSPO2 knockdown promoted the apoptosis of GCs, blocked the development of follicles, and delayed the onset of puberty with decreasing the expression level of Wnt signaling pathway-related genes (LGR4 and CTNNB1) in vivo. Taken together, the hypomethylation of -758/-749 and -563/-553 regions in RSPO2 promoter facilitated the occupancy of E2F1 and enhanced the transcription of RSPO2, which further promoted the proliferation and E2 secretion of GCs, inhibited the apoptosis of GCs, and ultimately ameliorated the development of follicles through Wnt signaling pathway. This study will provide useful information for further exploration on DNA-methylation-mediated RSPO2 pathway during follicular development.

The expression and mutation of BMPR1B and its association with litter size in small-tail Han sheep (Ovis aries)

Previous studies have shown that BMPR1B promotes follicular development and ovarian granulosa cell proliferation, thereby affecting ovulation in mammals. In this study, the expression and polymorphism of the BMPR1B gene associated with litter size in small-tail Han (STH) sheep were determined. The expression of BMPR1B was detected in 14 tissues of STH sheep during the follicular phase as well as in the hypothalamic–pituitary–gonadal (HPG) axis of monotocous and polytocous STH sheep during the follicular and luteal phases using quantitative polymerase chain reaction (qPCR). Sequenom MassARRAY^® single nucleotide polymorphism (SNP) technology was also used to detect the polymorphism of SNPs in seven sheep breeds. Here, BMPR1B was highly expressed in hypothalamus, ovary, uterus, and oviduct tissue during the follicular phase, and BMPR1B was expressed significantly more in the hypothalamus of polytocous ewes than in monotocous ewes during both the follicular and luteal phases (P<0.05). For genotyping, we found that genotype and allele frequencies of three loci of the BMPR1B gene were extremely significantly different (P<0.01) between the monotocous and polytocous groups. Association analysis results showed that the g.29380965A>G locus had significant negative effects on the litter size of STH sheep, and the combination of g.29380965A>G and FecB (Fec – fecundity and B – Booroola; A746G) at the BMPR1B gene showed that the litter size of AG–GG, AA–GG, and GG–GG genotypes was significantly higher compared with other genotypes (P<0.05). This is the first study to find a new molecular marker affecting litter size and to systematically analyze the expression of BMPR1B in different fecundity and physiological periods of STH sheep.

Molecular Characterization and Functional Analysis of Two Steroidogenic Genes TSPO and SMAD4 in Yellow Catfish

The steroid hormones are required for gonadal development in fish. The present study was undertaken to characterize the cDNA and promoter sequences of TSPO and SMAD4 genes in yellow catfish Pelteobagrus fulvidraco, explored the mRNA tissue expression and deciphered their promoter regions. Yellow catfish TSPO and SMAD4 shared the similar domains to the corresponding genes from other vertebrates. The TSPO and SMAD4 mRNAs were widely expressed in the detected tissues, but at different levels. Several transcription factors were predicted, such as Sp, GATA, AP1, SOX1, SRY, STAT, HNF4α, PPARγ, Pu.1 and FOXL2. PPARγ overexpression increased but STAT3 overexpression reduced TSPO promoter activity, and FOXL2 overexpression inhibited the promoter activity of TSPO and SMAD4. The site mutation and EMSA analysis indicated that TSPO promoter possessed STAT3 and FOXL2 sites. Overall, our provided the novel understanding into the transcriptionally regulatory mechanisms of TSPO and SMAD4 in fish.

Estrogen disorders: Interpreting the abnormal regulation of aromatase in granulosa cells (Review)

Ovarian granulosa cells (GCs) are the most important source of estrogen. Therefore, aromatase (estrogen synthase), which is the key enzyme in estrogen synthesis, is not only an important factor of ovarian development, but also the key to estrogen secretion by GCs. Disorders of the ovarian estrogen secretion are more likely to induce female estrogen-dependent diseases and fertility issues, such as ovarian cancer and polycystic ovary syndrome. Hence, aromatase is an important drug target; treatment with its inhibitors in estrogen-dependent diseases has attracted increasing attention. The present review article focuses on the regulation and mechanism of the aromatase activity in the GCs, as well as the specific regulation of aromatase promoters. In GCs, follicle-stimulating hormone (FSH) is dependent on the cyclic adenosine monophosphate (cAMP) pathway to regulate the aromatase activity, and the regulation of this enzyme is related to the activation of signaling pathways, such as phosphatidylinositol 3-kinase (PI3K) and extracellular signal-regulated kinase (ERK). In addition, endocrine-disrupting substance and other related factors affect the expression of aromatase, which eventually create an imbalance in the estrogen secretion by the target tissues. The present review highlights these useful factors as potential inhibitors for target therapy.

miR-18b regulates the function of rabbit ovary granulosa cells

MicroRNAs (miRNAs) have been determined to participate in the process of oestradiol production. Generally, there are two pathways by which oestradiol levels change, one being the state of cells (i.e. the status of enzymes involved in the synthesis of hormones such as oestradiol) and the other being the number of cells that secrete oestradiol. It is known that oestrogens are the main steroids produced by granulosa cells (GCs) of mature ovarian follicles. In this study we explored the function of miR-18b in rabbit GCs by overexpressing or inhibiting its activity. We found that miR-18b silencing promoted the secretion of oestradiol by significantly affecting the expression of steroidogenesis-related genes. Thus, miR-18b may act as a negative regulator of the production of enzymes related to oestradiol synthesis and affect oestradiol production. Furthermore, the effects of miR-18b on the proliferation, cell cycle and apoptosis of GCs were investigated using a cell counting kit (CCK-8) proliferation assay, detection of annexin V-fluorescein isothiocyanate apoptosis, flow cytometry and quantitative polymerase chain reaction. The results showed that miR-18b upregulated GC apoptosis (miR-18b overexpression decreases cell growth and stimulates apoptosis). These findings suggest that miR-18b and the oestrogen receptor 1 (ESR1) gene may be attractive targets to further explore the molecular regulation of GCs. The miR-18b may also explain, in part, the abnormal folliculogenesis in mammals caused by conditions such as polycystic ovary syndrome, primary ovarian insufficiency, and others.

Transcriptomic Data Analyses Reveal That Sow Fertility-Related lincRNA NORFA Is Essential for the Normal States and Functions of Granulosa Cells

NORFA, the first lincRNA associated with sow fertility, has been shown to control granulosa cell (GC) functions and follicular atresia. However, the underlying mechanism is not fully understood. In this study, RNA-seq was performed and we noticed that inhibition of NORFA led to dramatic transcriptomic alterations in porcine GCs. A total of 1,272 differentially expressed transcripts were identified, including 1167 DEmRNAs and 105 DEmiRNAs. Furthermore, protein-protein interaction, gene-pathway function, and TF-miRNA-mRNA regulatory networks were established and yielded four regulatory modules with multiple hub genes, such as AR, ATG5, BAK1, CENPE, NR5A1, NFIX, WNT5B, ssc-miR-27b, and ssc-miR-126. Functional assessment showed that these hub DEGs were mainly enriched in TGF-β, PI3K-Akt, FoxO, Wnt, MAPK, and ubiquitin pathways that are essential for GC states (apoptosis and proliferation) and functions (hormone secretion). In vitro, we also found that knockdown of NORFA in porcine GCs significantly induced cell apoptosis, impaired cell viability, and suppressed 17β-estradiol (E2) synthesis. Notably, four candidate genes for sow reproductive traits (INHBA, NCOA1, TGFβ-1, and TGFBR2) were also identified as potential targets of NORFA. These findings present a panoramic view of the transcriptome in NORFA-reduced GCs, highlighting that NORFA, a candidate lincRNA for sow fertility, is crucial for the normal states and functions of GCs.

Inhibition of microRNA-10b-5p up-regulates HOXD10 to attenuate Alzheimer's disease in rats via the Rho/ROCK signalling pathway

OBJECTIVE

It is believed that microRNAs (miRNAs) participate in the pathogenesis of Alzheimer's disease (AD), but the specified function of miR-10b-5p in the disease has not been thoroughly understood. Thereafter, this research aimed to assess the function of miR-10b-5p in AD.

METHODS

Rat AD models were established by injected with amyloid-β_1-42 (Aβ_1-42), which were mainly treated with lentivirus-miR-10b-5p inhibitor, or lentivirus-overexpressed homeobox D10 (HOXD10). MiR-10b-5p, HOXD10, RhoA, ROCK1 and ROCK2 expression in rat hippocampal tissues were determined. Afterwards, the behaviour of rats was tested, and neuronal apoptosis, pathological injury, and inflammatory factors and oxidative stress-related factors were all assessed. Finally, the target relation between miR-10b-5p and HOXD10 was detected.

RESULTS

MiR-10b-5p was upregulated while HOXD10 was downregulated, and the Rho/ROCK signalling pathway was activated in hippocampal tissues of rats with AD. Inhibition of miR-10b-5p could attenuate the neuronal apoptosis, pathological injury, inflammation reaction, and oxidative stress by elevating HOXD10 and inhibiting the Rho/ROCK signalling pathway in AD rats. Moreover, HOXD10 was targeted by miR-10b-5p.

CONCLUSION

Inhibited miR-10b-5p decelerated the development of AD by promoting HOXD10 and inactivating the Rho/ROCK signalling pathway, and our findings may contribute to the exploration of AD treatment.

Upregulation of miR-146b promotes porcine ovarian granulosa cell apoptosis by attenuating CYP19A1

MicroRNAs (miRNAs) are 21- to 24-nucleotide long small noncoding RNAs, which play an important role in follicular atresia and granulosa cell (GC) apoptosis in the mammalian ovary. Here, we report that miR-146b, a conserved and ovary-enriched miRNA, modulates estradiol (E2) secretion, GC apoptosis, and follicular atresia in pigs. Genome-wide analysis and quantitative real-time PCR revealed that miR-146b was significantly upregulated during follicular atresia, and fluorescence-activated cell sorting showed that miR-146b functioned as a proapoptotic factor to induce GC apoptosis. MicroRNA-mRNA network analysis and luciferase reporter assays showed that CYP19A1, the pivotal enzyme for E2 synthesis signaling, was directly targeted by miR-146b. Furthermore, miR-146b interacted with the 3'untranslated region of CYP19A1 to prevent translation, thereby regulating CYP19A1-mediated E2 secretion and GC apoptosis. However, miR-146b was not regulated by the transcription factor SMAD4 or oxidative stress, both of which are critical regulators of CYP19A1. We, thus, conclude that miR-146b is a novel epigenetic factor regulating GC functions, follicular development, and female reproduction.

Identification of Functional Single Nucleotide Polymorphisms in Porcine HSD17B14 Gene Associated with Estrus Behavior Difference between Large White and Mi Gilts

Steroid hormone levels are associated with estrous behavior, which affects timely mating and reproductive efficiency in pigs. 17β-hydroxysteroid dehydrogenase type 14 (HSD17B14) modulates steroid synthesis and metabolism. To identify the functional single nucleotide polymorphisms (SNPs) in the porcine HSD17B14 gene, ear tissues from Large White and Mi gilts were collected to extract genomic DNA. Variable lengths of truncated promoter of HSD17B14 gene were used to determine the promoter activity by a dual luciferase reporter system. The vector HSD17B14^Phe or HSD17B14^Val was transfected into porcine granulosa cells (GCs). The core promoter region was identified between -72bp and -218bp. Six of seven SNPs had significant differences of allele frequency between Large White and Mi gilts. The plasmids with the wild genotype AA of rs329427898 maintained a smaller fraction of promoter activity compared with the plasmids with the mutant genotype GG, while the plasmids with wild the genotype TT of rs319864566 had a greater promoter activity than the plasmids with the mutant genotype CC. A missense mutation (Phe73Val) caused changes in the structural dynamics and function of the HSD17B14 protein. The highly expressed HSD17B14^Val degraded less estradiol into estrone, while the relatively lowly expressed HSD17B14^Phe degraded more estradiol into estrone, suggesting the protein activity of HSD17B14^Phe was greater than that of HSD17B14^Val. Moreover, the HSD17B14^Phe group has a greater apoptosis rate of porcine GCs. The HSD17B14 gene could been used as a candidate molecular marker for estrus behavior in pigs.

TGF-β1 controls porcine granulosa cell states: A miRNA-mRNA network view

TGF-β1, an important multi-functional cytokine of the TGF-β signaling pathway, has been reported to be crucial for ovarian granulosa cell (GC) states and female fertility. However, the molecular mechanism underlying TGF-β1 regulation of GC states remains largely unknown. Here, we provide a comprehensive transcriptomic view on TGF-β1 regulation of cell states in porcine GCs. We first confirmed that TGF-β1 can control GC states (apoptosis and proliferation) in pig ovary. RNA-seq showed that 909 differentially expressed genes (DEGs), including 890 DEmRNAs and 19 DEmiRNAs, were identified in TGF-β1-treated porcine GCs. Functional annotation showed that these DEGs were mainly involved in regulating cell states. In addition, multiple hub genes were identified by constructing the protein-protein interaction network, DEmiRNA-DEmRNAs regulatory network, and gene-pathway-function co-expression networks, which were further found to be enriched in FoxO, TGF-β, Wnt, PIK3-Akt, p53 and Ras signaling pathways that play important roles in regulating cell states, cell cycle, proliferation, stress-responses and inflammation. The current research deeply reveals the effects of TGF-β1 on porcine GCs, and also identifies potential therapeutic RNA molecules for inhibiting and rescuing female infertility.

MiR-214-3p promotes proliferation and inhibits estradiol synthesis in porcine granulosa cells

Background

Granulosa cells (GCs) proliferation and estradiol synthesis significantly affect follicular development. The miR-214-3p expression in the ovarian tissues of high-yielding sows is higher than that in low-yielding sows, indicating that miR-214-3p may be involved in sow fertility. However, the functions and mechanisms of miR-214-3p on GCs are unclear. This study focuses on miR-214-3p in terms of the effects on GCs proliferation and estradiol synthesis.

Results

Our findings revealed that miR-214-3p promotes proliferation and inhibits estradiol synthesis in porcine GCs. MiR-214-3p can increase the percentage of S-phase cells, the number of EdU labeled positive cells, and cell viability. However, E₂ concentration was reduced after miR-214-3p agomir treatment. We also found that miR-214-3p up-regulates the expression of cell cycle genes including cell cycle protein B (Cyclin B), cell cycle protein D (Cyclin D), cell cycle protein E (Cyclin E), and cyclin-dependent kinase 4 (CDK4) at the transcription and translation levels, but down-regulates the mRNA and protein levels of cytochrome P450 family 11 subfamily A member 1 (CYP11A1), cytochrome P450 family 19 subfamily A member 1 (CYP19A1), and steroidogenic acute regulatory protein (StAR) (i.e., the key enzymes in estradiol synthesis). On-line prediction, bioinformatics analysis, a luciferase reporter assay, RT-qPCR, and Western blot results showed that the target genes of miR-214-3p in proliferation and estradiol synthesis are Mfn2 and NR5A1, respectively.

Conclusions

Our findings suggest that miR-214-3p plays an important role in the functional regulation of porcine GCs and therefore may be a target gene for regulating follicular development.

miR-361-5p Mediates SMAD4 to Promote Porcine Granulosa Cell Apoptosis through VEGFA

Follicular atresia is an inevitable degenerative process that occurs in mammalian ovarian follicles. The molecular events involved in atresia, particularly granulosa cell apoptosis, have long attracted researchers’ attention. Vascular endothelial growth factor A (VEGFA) is downregulated during follicular atresia in porcine ovaries and serves as an inhibitor of apoptosis in granulosa cells. In addition, transforming growth factor (TGF)-βsignaling has been considered a central trigger in granulosa cell apoptosis. However, the link between TGF-β signaling and VEGFA is unknown. We proved that miR-361-5p is significantly upregulated during the atresia process and that it promotes GC apoptosis by directly targeting the VEGFA 3′UTR. In addition, we revealed that the miR-361-5p coding gene MIR361 was significantly downregulated by SMAD4, the central intracellular mediator of TGF-β signaling, that bound to the MIR361 promoter. In conclusion, our findings expanded what is known about VEGFA posttranscriptional regulation and revealed a complete SMAD4/miR-361-5p/VEGFA regulatory network in ovarian granulosa cell apoptosis. These data provide useful references for follicular atresia and ovarian physiological function studies.

miR-130a/TGF-β1 axis is involved in sow fertility by controlling granulosa cell apoptosis

TGF-β1 is a ligand of the TGF-β superfamily and an important cytokine that regulates ovarian functions including follicular development, steroid production, ovulation, luteinization, and female fertility. However, little is known about the regulation of TGF-β1 expression in ovary. Here, we identified that TGF-β1 is a functional target of miR-130a in porcine ovarian granulosa cells (GCs). The 3'-UTR sequence of TGF-β1 gene (1137 bp in length) in Large White (LW) pig was isolated, and multiple RNA regulatory elements (RREs), including several binding motifs of different miRNAs, were identified in this region. Luciferase activity assay showed that miR-130a dramatically suppresses the 3'-UTR luciferase activity of TGF-β1 gene, and further inhibits the expression of TGF-β1 in porcine GCs. FACS revealed that miR-130a acts as a pro-apoptotic factor and promotes GC apoptosis by inhibiting TGF-β1. Two novel linked mutations (-573G > A and -540T  >  C) were identified in the promoter region of ssc-miR-130a, but their polymorphisms are not associated with sow reproductive traits. Importantly, combined genotype analysis with a known mutation (c.1583 A  >  G) in the 3'-UTR of porcine TGF-β1 gene showed a significant association with reproductive performance in LW sow population. Overall, our findings defined a novel regulatory axis, miR-130a/TGF-β1 axis, which is involved in regulating sow fertility.

Cortical Granule Distribution and Expression Pattern of Genes Regulating Cellular Component Size, Morphogenesis, and Potential to Differentiation are Related to Oocyte Developmental Competence and Maturational Capacity In Vivo and In Vitro

Polyspermia is an adverse phenomenon during mammalian fertilization when more than one sperm fuses with a single oocyte. The egg cell is prepared to prevent polyspermia by, among other ways, producing cortical granules (CGs), which are specialized intracellular structures containing enzymes that aim to harden the zona pellucida and block the fusion of subsequent sperm. This work focused on exploring the expression profile of genes that may be associated with cortical reactions, and evaluated the distribution of CGs in immature oocytes and the peripheral density of CGs in mature oocytes. Oocytes were isolated and then processed for in vitro maturation (IVM). Transcriptomic analysis of genes belonging to five ontological groups has been conducted. Six genes showed increased expression after IVM (ARHGEF2, MAP1B, CXCL12, FN1, DAB2, and SOX9), while the majority of genes decreased expression after IVM. Using CG distribution analysis in immature oocytes, movement towards the cortical zone of the oocyte during meiotic competence acquisition was observed. CGs peripheral density decreased with the rise in meiotic competence during the IVM process. The current results reveal important new insights into the in vitro maturation of oocytes. Our results may serve as a basis for further studies to investigate the cortical reaction of oocytes.

SMAD4 activates Wnt signaling pathway to inhibit granulosa cell apoptosis

The TGF-β and Wnt signaling pathways are interrelated in many cell types and tissues, and control cell functions in coordination. Here, we report that SMAD4, a downstream effector of the TGF-β signaling pathway, induces FZD4, a receptor of the Wnt signaling pathway, establishing a novel route of communication between these two pathways in granulosa cells (GCs). We found that SMAD4 is a strong inducer of FZD4, not only initiating FZD4 transcription but also activating FZD4-dependent Wnt signaling and GC apoptosis. Furthermore, we identified the direct and indirect mechanisms by which SMAD4 promotes expression of FZD4 in GCs. First, SMAD4 functions as a transcription factor to directly bind to the FZD4 promoter region to increase its transcriptional activity. Second, SMAD4 promotes production of SDNOR, a novel lncRNA that acts as a sponge for miR-29c, providing another mean to block miR-29c from degenerating FZD4 mRNA. Overall, our findings not only reveal a new channel of crosstalk between the TGF-β and Wnt signaling pathways, SMAD4–FZD4 axis, but also provide new insights into the regulatory network of GC apoptosis and follicular atresia. These RNA molecules, such as miR-29c and lnc-SDNOR, represent potential targets for treatment of reproductive diseases and improvement of female fertility.

A putative protein-RNA complex regulates posttranscriptional processing of cytochrome P450 aromatase (CYP19A1) in bovine granulosa cells

Follicle growth and granulosa cell health are dependent on the secretion of estradiol from granulosa cells. Estradiol is synthesized from androgen precursor by cytochrome P450 aromatase (CYP19A1), and in cattle CYP19A1 messenger RNA has a short half-life but a long (3.5 kb) 3'-untranslated region (3'UTR), suggesting that posttranscriptional regulation may be important for control of enzyme activity. We tested this hypothesis by inserting the CYP19A1 3'UTR and fragments thereof into a reporter vector between the end of the luciferase coding region and the polyadenylation signal. The full-length aromatase 3'UTR suppressed luciferase activity to 10% of control levels, and smaller fragments showed that this inhibitory activity lies between +926 and +1134 of the 3'UTR. Protein-RNA cross-linking experiments revealed that these 3'UTR fragments formed an RNA-protein complex of approximately 70 kDa that was present in granulosa cells but not in corpus luteum, lung, liver, kidney, pancreas, or bladder extracts. The RNA-binding activity was specific to the 3'UTR, as shown by competition experiments with unlabeled RNA, and was present only in 3'UTR constructs that inhibited luciferase activity. These data suggest that posttranscriptional regulation is an important component of the control of CYP19A1 expression and involves protein binding to a specific sequence in the 3'UTR.

Variants in BMP7 and BMP15 3'-UTRs Associated with Reproductive Traits in a Large White Pig Population

Bone morphogenetic protein 7 (BMP7) and BMP15, which encode members of the BMP family, have been identified by whole-genome resequencing as breeding-related genes that overlap with a known quantitative trait locus for reproductive traits. In this study, we investigated the effects of variants at the BMP7 and BMP15 gene loci on sow reproductive traits. We isolated 669 and 1213 bp sequences of the 3’-untranslated region (3’-UTR) of the porcine BMP7 and BMP15 genes, respectively, and detected several RNA regulatory elements, such as miRNA response elements and AU-rich elements. Pooled DNA sequencing identified two novel point mutations (viz., BMP7 c.1569A>G and BMP15 c.2366G>A) in the 3’-UTR. Association analysis showed that the c.1569A>G polymorphism was associated with the litter weight trait in a Large White pig population. Furthermore, analysis of the combined genetic effects revealed that AA/GA and AG/GG were the favorable combined genotypes for the total number of piglets born (TNB) and the total number of piglets born alive (NBA), whereas. Together, our findings confirm that BMP7 and BMP15 are candidate genes for porcine reproductive performance.

Smad4 Feedback Enhances BMPR1B Transcription in Ovine Granulosa Cells

BMPR1B is a type 1B receptor of the canonical bone morphogenetic protein (BMP)/Sma- and mad-related protein (Smad) signaling pathway and is well known as the first major gene associated with sheep prolificacy. However, little is known about the transcriptional regulation of the ovine BMPR1B gene. In this study, we identified the ovine BMPR1B gene promoter and demonstrated that its transcription was regulated by Smad4. In sheep ovarian follicles, three transcriptional variants of BMPR1B gene with distinct transcription start sites were identified using 5′ RACE assay while variants II and III were more strongly expressed. Luciferase assay showed that the region −405 to −200 nt is the PII promoter region of variant II. Interestingly, two putative Smad4-binding elements (SBEs) were detected in this region. Luciferase and ChIP assay revealed that Smad4 enhances PII promoter activity of the ovine BMPR1B gene by directly interacting with SBE1 motif. Furthermore, in the ovine granulosa cells, Smad4 regulated BMPRIB expression, and BMPRIB-mediated granulosa cells apoptosis. Overall, our findings not only characterized the 5’ regulatory region of the ovine BMPR1B gene, but also uncovered a feedback regulatory mechanism of the canonical BMP/Smad signaling pathway and provided an insight into the transcriptional regulation of BMPR1B gene and sheep prolificacy.

Transcriptome Analysis of Male and Female Mature Gonads of Silver Sillago (Sillago sihama)

Silver sillago (Sillago sihama) is an emerging commercial marine aquaculture species in China. To date, fundamental information on S. sihama, such as genomic information, is lacking, and no data are available on the gonad transcriptome of S. sihama. Here, the first gonadal transcriptomes of S. sihama have been constructed and genes potentially involved in gonadal development and reproduction identified. Illumina sequencing generated 60.18 million clean reads for the testis and 59.10 million for the ovary. All reads were assembled into 74,038 unigenes with a mean length of 1,004 bp and N50 value of 2,190 bp. Among all the predictable unigenes, a total of 34,104 unigenes (46%) were searched against multiple databases, including 33,244 unigenes annotated in the RefSeq Non- Redundant database at NCBI, and 28,924 in Swiss-Prot. By comparing the ovary and testis, 35,367 unigenes were identified as being differentially expressed between males and females, of which 29,127 were upregulated in the testis and 6,240 were upregulated in the ovary. Numerous differentially expressed genes (DEGs) known to be involved in gonadal development and gametogenesis were identified, including amh, dmrt1, gsdf, cyp19a1a, gnrhr, and zps. Using gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses, the top 20 KEGG pathways with highest number of DEGs were found to be involved in regulating gonadal development and gametogenesis in S. sihama. Moreover, 22,666 simple sequence repeats (SSRs) were identified in 14,577 SSR-containing sequences. The findings provide a valuable dataset for future functional analyses of sex-associated genes and molecular marker assisted selection in S. sihama.