High ovarian GDF-8 levels contribute to elevated estradiol production in ovarian hyperstimulation syndrome by stimulating aromatase expression

Sulforaphane Promotes Proliferation of Porcine Granulosa Cells via the H3K27ac-Mediated GDF8-ALK5-ERK Pathway

Follicle development, a crucial process in reproductive biology, hinges upon the dynamic proliferation of granulosa cells (GCs). Growth differentiation factor-8 (GDF8) is well-known as myostatin for inhibiting skeletal muscle growth, and it also exists in ovarian GCs and follicle fluid. However, the relationship between GCs proliferation and GDF8 remains elusive. Sulforaphane (SFN) is a potent bioactive compound, which in our study has been demonstrated to induce the expression of GDF8 in GCs. Meanwhile, we discover a novel role of SFN in promoting the proliferation of porcine GCs. Specifically, SFN enhances GCs proliferation by accelerating the progression of the cell cycle through the G1 phase to the S phase. By performing gene expression profiling, we showed that the promoting proliferative effects of SFN are highly correlated with the TGF-β signaling pathways and cell cycle. Among the ligand factors of TGF-β signaling, we identify GDF8 as a critical downstream effector of SFN, which acts through ALK5 to mediate SFN-induced proliferation and G1/S transition. In addition, we identify a noncanonical downstream pathway by which GDF8 induces the activation of MAPK/ERK to facilitate the cell cycle progression in GCs. Moreover, we reveal that the expression of GDF8 is regulated by SFN through epigenetic modifications of H3K27 acetylation. These findings not only provide mechanistic insights into the regulation of GCs proliferation but also establish a previously unrecognized role of GDF8 in follicle development, which have significant implications for developing strategies to improve female fertility.

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.

TGF-β1 and TGF-β3, but not TGF-β2, are upregulated in the ovaries of ovarian hyperstimulation syndrome†

Ovarian hyperstimulation syndrome (OHSS) is a life-threatening and potentially fatal complication during in vitro fertilization treatment. The levels of transforming growth factor-β1 (TGF-β1) are upregulated in human follicular fluid and granulosa-lutein cells (hGL) of OHSS patients and could contribute to the development of OHSS by downregulating steroidogenic acute regulatory protein (StAR) expression. However, whether the same is true for the other two members of the TGF-β family, TGF-β2 and -β3, remains unknown. We showed that all three TGF-β isoforms were expressed in human follicular fluid. In comparison, TGF-β1 was expressed at the highest level, followed by TGF-β2 and TGF-β3. Compared to non-OHSS patients, follicular fluid levels of TGF-β1 and TGF-β3 were significantly upregulated in OHSS patients. The same results were observed in mRNA levels of TGF-β isoforms in hGL cells and ovaries of OHSS rats. In addition, StAR mRNA levels were upregulated in hGL cells of OHSS patients and the ovaries of OHSS rats. Treatment cells with TGF-β isoforms downregulated the StAR expression with a comparable effect. Moreover, activations of SMAD3 signaling were required for TGF-β isoforms-induced downregulation of StAR expression. This study indicates that follicular fluid TGF-β1 and TGF-β3 levels could be used as biomarkers and therapeutic targets for the OHSS.

Possible Mechanisms Linking Obesity, Steroidogenesis, and Skeletal Muscle Dysfunction

Increasing evidence suggests that skeletal muscles may play a role in the pathogenesis of obesity and associated conditions due to their impact on insulin resistance and systemic inflammation. Skeletal muscles, as well as adipose tissue, are largely recognized as endocrine organs, producing biologically active substances, such as myokines and adipokines. They may have either beneficial or harmful effects on the organism and its functions, acting through the endocrine, paracrine, and autocrine pathways. Moreover, the collocation of adipose tissue and skeletal muscles, i.e., the amount of intramuscular, intermuscular, and visceral adipose depots, may be of major importance for metabolic health. Traditionally, the generalized and progressive loss of skeletal muscle mass and strength or physical function, named sarcopenia, has been thought to be associated with age. That is why most recently published papers are focused on the investigation of the effect of obesity on skeletal muscle function in older adults. However, accumulated data indicate that sarcopenia may arise in individuals with obesity at any age, so it seems important to clarify the possible mechanisms linking obesity and skeletal muscle dysfunction regardless of age. Since steroids, namely, glucocorticoids (GCs) and sex steroids, have a major impact on the amount and function of both adipose tissue and skeletal muscles, and are involved in the pathogenesis of obesity, in this review, we will also discuss the role of steroids in the interaction of these two metabolically active tissues in the course of obesity.

TGF-β1 upregulates secreted protein acidic and rich in cysteine expression in human granulosa-lutein cells: a potential mechanism for the pathogenesis of ovarian hyperstimulation syndrome

BACKGROUND

Ovarian hyperstimulation syndrome (OHSS) is a serious complication during in vitro fertilization (IVF) treatment. The upregulation of ovarian transforming growth factor-beta 1 (TGF-β1) is involved in the development of OHSS. The secreted protein acidic and rich in cysteine (SPARC) is a secreted multifunctional matricellular glycoprotein. Although the regulatory effects of TGF-β1 on SPARC expression have been reported, whether TGF-β1 regulates SPARC expression in the human ovary remains unknown. In addition, the role of SPARC in the pathogenesis of OHSS is unclear.

METHODS

A steroidogenic human ovarian granulosa-like tumor cell line, KGN, and primary culture of human granulosa-lutein (hGL) cells obtained from patients undergoing IVF treatment were used as experimental models. OHSS was induced in rats, and ovaries were collected. Follicular fluid samples were collected from 39 OHSS and 35 non-OHSS patients during oocyte retrieval. The underlying molecular mechanisms mediating the effect of TGF-β1 on SPARC expression were explored by a series of in vitro experiments.

RESULTS

TGF-β1 upregulated SPARC expression in both KGN and hGL cells. The stimulatory effect of TGF-β1 on SPARC expression was mediated by SMAD3 but not SMAD2. The transcription factors, Snail and Slug, were induced in response to the TGF-β1 treatment. However, only Slug was required for the TGF-β1-induced SPARC expression. Conversely, we found that the knockdown of SPARC decreased Slug expression. Our results also revealed that SPARC was upregulated in the OHSS rat ovaries and in the follicular fluid of OHSS patients. Knockdown of SPARC attenuated the TGF-β1-stimulated expression of vascular endothelial growth factor (VEGF) and aromatase, two markers of OHSS. Moreover, the knockdown of SPARC reduced TGF-β1 signaling by downregulating SMAD4 expression.

CONCLUSIONS

By illustrating the potential physiological and pathological roles of TGF-β1 in the regulation of SPARC in hGL cells, our results may serve to improve current strategies used to treat clinical infertility and OHSS. Video Abstract.

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.

Biomarkers identification in follicular fluid of women with OHSS by using UPLC-MS method

To figure out the differentially changed metabolites and disturbed pathways in follicular fluid (FF) of patients with OHSS in comparison to the control group undergoing in vitro fertilization (IVF), we conducted this metabolomic analysis between two groups, the OHSS group included 30 patients treated with oocyte retrieval and developed OHSS in the next 7-14 days, while another 30 patients without OHSS tendency were selected as the control group. The FF samples were obtained during the process of oocyte retrieval. FF samples were analyzed using ultra-high liquid chromatography-tandem mass spectrometry (UPLC-MS). The results identified a total of 59 differentially changed metabolites, including 33 decreased metabolites (P < 0.01) and 26 increased metabolites (P < 0.01) in FF of OHSS compared with the control group. 12 metabolites could be the most valuable biomarkers for OHSS based on ROC results. Our correlation analyses showed that deoxyinosine levels were found positively correlated with serum estradiol (E2) levels in OHSS patients, while L-isoleucine, pyruvic acid, maleamate, and arachidonic acid were found to be positively correlated with the number of retrieved oocytes. Furthermore, 4-hydroxyphenylacetaldehyde, deoxycorticosterone, creatinine, and creatine were found to be negatively associated with serum E2 levels, while 4-hydroxyphenylacetaldehyde, L-carnitine, isovaleric acid and L-2-hydroxyglutaric acid were negatively related with the number of oocytes retrieved in OHSS patients. Taken together, our study provides better identification of OHSS FF metabolic dynamics, suggesting the metabolic compounds can be used as valuable predictors or treatment targets of OHSS.

Fibroblast growth factor 21 (FGF21) promotes porcine granulosa cell estradiol production and proliferation via PI3K/AKT/mTOR signaling

The proliferation and steroidogenesis of mammalian ovarian granulosa cells (GCs) are related to follicular development. Previous studies found that fibroblast growth factor 21 (FGF21) regulated female fertility through the hypothalamic-pituitary-gonad axis. However, FGF21 receptors are expressed on GCs, so we speculate that it might affect female reproduction by regulating their physiological activities. Here, we showed that FGF21, fibroblast growth factor receptor-1(FGFR1), and beta-klotho (KLB) were expressed in porcine GCs. ELISA assays showed that estradiol (E₂) production was increased significantly when treating GCs with recombinant FGF21 (rFGF21). In addition, rFGF21 upregulated the mRNA and protein levels of E₂ synthesis-related genes including StAR, CYP11A1, and CYP19A1 in porcine GCs. Correspondingly, FGF21 siRNA inhibited E₂ levels and its synthesis-related gene expression. After rFGF21 treatment, CCK8 showed increased cell viability, and flow cytometry showed that the number of S phase increased, and cycle-related genes also increased. However, treatment with FGF21 siRNA to porcine GCs suppressed the cell cycle, viability, and EdU positive cell number. Consequently, FGF21/FGFR1/KLB forms a complex to activate the phosphatidylinositol-3-kinase (PI3K)/AKT/mTOR signaling pathway and further promote the proliferation and E₂ synthesis in porcine GCs. Collectively, these findings suggests that FGF21 regulates porcine ovarian folliculogenesis.

Myostatin: a multifunctional role in human female reproduction and fertility - a short review

Myostatin (MSTN) is member of the transforming growth factor β (TGF-β) superfamily and was originally identified in the musculoskeletal system as a negative regulator of skeletal muscle growth. The functional roles of MSTN outside of the musculoskeletal system have aroused researchers' interest in recent years, with an increasing number of studies being conducted in this area. Notably, the expression of MSTN and its potential activities in various reproductive organs, including the ovary, placenta, and uterus, have recently been examined. Numerous studies published in the last few years demonstrate that MSTN plays a critical role in human reproduction and fertility, including the regulation of follicular development, ovarian steroidogenesis, granule-cell proliferation, and oocyte maturation regulation. Furthermore, findings from clinical samples suggest that MSTN may play a key role in the pathogenesis of several reproductive disorders such as uterine myoma, preeclampsia (PE), ovary hyperstimulation syndrome (OHSS), and polycystic ovarian syndrome (PCOS). There is no comprehensive review regarding to MSTN related to the female reproductive system in the literature. This review serves as a summary of the genes in reproductive medicine and their potential influence. We summarized MSTN expression in different compartments of the female reproductive system. Subsequently, we discuss the role of MSTN in both physiological and several pathological conditions related to the female fertility and reproduction-related diseases.

Regulatory Role and Potential Importance of GDF-8 in Ovarian Reproductive Activity

Growth differentiation factor-8 (GDF-8) is a member of the transforming growth factor-beta superfamily. Studies in vitro and in vivo have shown GDF-8 to be involved in the physiology and pathology of ovarian reproductive functions. In vitro experiments using a granulosa-cell model have demonstrated steroidogenesis, gonadotrophin responsiveness, glucose metabolism, cell proliferation as well as expression of lysyl oxidase and pentraxin 3 to be regulated by GDF-8 via the mothers against decapentaplegic homolog signaling pathway. Clinical data have shown that GDF-8 is expressed widely in the human ovary and has high expression in serum of obese women with polycystic ovary syndrome. GDF-8 expression in serum changes dynamically in patients undergoing controlled ovarian hyperstimulation. GDF-8 expression in serum and follicular fluid is correlated with the ovarian response and pregnancy outcome during in vitro fertilization. Blocking the GDF-8 signaling pathway is a potential therapeutic for ovarian hyperstimulation syndrome and ovulation disorders in polycystic ovary syndrome. GDF-8 has a regulatory role and potential importance in ovarian reproductive activity and may be involved in folliculogenesis, ovulation, and early embryo implantation.