Activin A attenuates apoptosis of granulosa cells in atretic follicles through ERβ-induced autophagy

TGF-β1 Mediates Novel-m0297-5p Targeting WNT5A to Participate in the Proliferation of Ovarian Granulosa Cells in Small-Tailed Han Sheep

MiRNAs regulate follicle development and atresia, steroid production, granulosa cell (GC) proliferation, and apoptosis. However, the target genes and the functioning of novel miRNAs remain unexplored. We reveal the targeting relationship between novel-m0297-5p and WNT5A and the specific regulatory mechanism of GC proliferation in small-tailed Han sheep using whole transcriptomic sequencing. We performed whole transcriptomic sequencing on small-tailed Han sheep ovarian GCs supplemented with 10 ng/mL of transforming growth factor-β1 (TGF-β1) during the early stages. This led to identifying the differential expression of novel-m0297-5p and Wnt family member 5A (WNT5A) and predicting their targeting relationship. Based on this, we hypothesized that TGF-β1 could mediate novel-m0297-5p targeting WNT5A to participate in the proliferation process of GCs in small-tailed sheep. We confirmed the relationship between TGF-β1 and both novel-m0297-5p and WNT5A. The mimicry of novel-m0297-5p inhibited GC activity and proliferation. However, the inhibition of novel-m0297-5p yielded the opposite effect. We validated the binding site for novel m0297-5p within the 3'UTR of WNT5A using dual-luciferase reporter gene. TGF-β1 alleviated the impact induced by the mimicry of novel-m0297-5p on cell viability. Inhibitor co-transfection for both novel-m0297-5p and si-WNT5A suppressed the granulocyte proliferation induced by novel-m0297-5p inhibition. These findings suggest that TGF-β1 can mediate the inhibitory effect of novel-m0297-5p targeting WNT5A on GC proliferation and activity in small-tailed Han sheep. This study provides an experimental basis for research on the biological function of GCs and their impact on follicle development.

Unraveling the complexity of follicular fluid: insights into its composition, function, and clinical implications

Follicular fluid (FF) plays a vital role in the bidirectional communication between oocytes and granulosa cells (GCs), regulating and promoting oocyte growth and development. This fluid constitutes a complex microenvironment, rich in various molecules including hormones, growth factors, cytokines, lipids, proteins, and extracellular vesicles. Understanding the composition and metabolic profile of follicular fluid is important for investigating ovarian pathologies such as polycystic ovary syndrome (PCOS) and endometriosis. Additionally, analyzing follicular fluid can offer valuable insights into oocyte quality, aiding in optimal oocyte selection for in vitro fertilization (IVF). This review provides an overview of follicular fluid composition, classification of its components and discusses the influential components of oocyte development. It also highlights the role of follicular fluid in the pathogenesis and diagnosis of ovarian diseases, along with potential follicular fluid biomarkers for assessing oocyte quality. By understanding the intricate relationship between follicular fluid and oocyte development, we can advance fertility research and improve clinical outcomes for infertility patients.

HD-sEVs in bovine follicular fluid regulate granulosa cell apoptosis and estradiol secretion through the autophagy pathway

Follicular fluid (FF) is rich in extracellular vesicles (EVs), which have regulatory effects on follicular growth and oocyte development. EVs can be divided into two subtypes, i.e. HD-sEVs and LD-sEVs. In this study, HD-sEVs were successfully isolated from bovine follicular fluid (BFF) by density gradient ultracentrifugation. By western blot, quantitative polymerase chain reaction (qPCR), flow cytometry, transmission electron microscopy (TEM) and enzyme-linked immunosorbent assay (ELISA), this study found HD-sEVs promoted autophagy in bGCs by increasing the protein and mRNA expression of LC3II/LC3I ratio and Beclin1, and inhibiting the protein and mRNA expression of p62. HD-sEVs promoted mitophagy in bGCs by increasing the protein and mRNA expression of VDAC1, CTSD, and HSP60. Flow cytometry showed that HD-sEVs inhibited bGCs apoptosis rate. HD-sEVs promoted estradiol secretion by increasing steroidogenesis-associated proteins and mRNA, such as CYP19A, HSD3B in bGCs. HD-sEVs promoted autophagosome formation and mitochondrial structure swelling in bGCs, and decreased p-mTOR/mTOR ratio. The above phenomenon was reversed when wortmannin was added. Collectively, BFF HD-sEVs promote bGCs autophagy and mitophagy, inhibit bGCs apoptosis and promote estradiol secretion through the autophagy pathway-mTOR signaling pathway.

MiR-29c-5p regulates the function of buffalo granulosa cells to induce follicular atresia by targeting INHBA

MicroRNAs (miRNAs) are involved in many physiological processes such as signal transduction, cell proliferation and apoptosis. Many studies have shown that miRNAs can regulate the process of follicular development. Our previous studies found that the expression of miR-29c-5p in buffalo atretic follicles was much higher than that in healthy follicles, suggesting that this miRNA may participate in the process of buffalo follicular atresia. In this study, we aim to explore to the role and molecular mechanisms of miR-29c-5p on the functions of buffalo granulosa cells (GCs). GCs cultured in vitro were transfected with miR-29c-5p mimics and its inhibitor, respectively, and it was found that the mimics significantly increased the apoptotic rate of GCs. They also inhibited the proliferation of GCs and the secretion of steroid hormones. The effect of the inhibitor was opposite to that of the mimics. MiR-29c-5p was subsequently shown to target the inhibin subunit beta A, (INHBA). Overexpression of INHBA could promote the production of activin A and inhibin A, and then reverse the effect of miR-29c-5p on buffalo GCs. In conclusion, these results suggest that miR-29c-5p promotes apoptosis and inhibits proliferation and steroidogenesis by targeting INHBA in buffalo GCs. This may ultimately promote atresia in buffalo follicles.

Activin A Reduces Porcine Granulosa Cells Apoptosis via ERβ-Dependent ROS Modulation

Unfavorable conditions compromise animal reproduction by altering the ovarian granulosa cells' follicular dynamics and normal physiological function (GCs), eventually resulting in oxidative damage and cell apoptosis. Activin is produced in the GCs and plays a vital role in folliculogenesis. This study investigated the effects of activin A (ACT-A) treatment in vitro on the apoptosis of porcine GCs and the underlying molecular mechanism. We found that ACT-A could attenuate the apoptosis of the GCs and enhance the synthesis of estrogen (E2). ACT-A also enhanced FSH-induced estrogen receptor-β (ERβ) expression, inhibiting ERβ aggravated intracellular accumulation of the reactive oxygen species (ROS) and apoptosis. The E2 levels in the culture medium, the mRNA expression pattern of the apoptosis-related genes (CASPASE 3, BCL2, and BAX), steroidogenesis-related gene (CYP19A1), and cell viability were analyzed to confirm the results. In summary, this study indicated the protective role of ACT-A in apoptosis by attenuating the ROS accumulation through ERβ. These results aim to enhance the follicular functions and improve animal reproductive performance.

Expression of ERβ induces Bovine Ovarian Granulosa Cell Autophagy via the AKT/mTOR Pathway

The aim of our study was to determine whether silencing or overexpression of Estrogen Receptor β (ERβ) regulates cell proliferation, steroidogenesis, autophagy and signaling pathways in bovine ovarian granulosa cells in vitro. In this study, bovine ovarian granulosa cells (BGCs) were cultured and transfected with ERβ siRNA (si-ERβ) or a plasmid overexpressing ERβ (oe-ERβ), and CCK-8 kit was used to assess cell proliferation. Real-time PCR was used to measure gene transcription. Western blotting was used to measure protein expression, and a specific kit was used to measure the production of steroid hormones. The results showed the expression level of ERβ affects BGC proliferation according to the gene transcription levels of FSHR, CYP19A1, HSD3β1 and STAR and the production of E2 and P4. ERβ was identified as an important nuclear receptor that induced BGC autophagy based on the mRNA and protein expression of autophagy-related genes. Furthermore, the role of ERβ in BGC autophagy was confirmed through treatment with rapamycin (RAPA) or 3-methyladenine (3-MA) in BGCs by cotransfection with si-ERβ or oe-ERβ in BGCs. The results related to AKT/mTOR signaling and phosphorylation suggested that ERβ induces BGC autophagy through attenuating AKT/mTOR signaling. In summary, this study demonstrates that silencing or overexpression of ERβ regulates BGC proliferation and function and induces BGC autophagy by targeting AKT/mTOR signaling. These data reveal a novel regulatory mechanism of autophagy via ERβ and provide insights into the role of autophagy in BGCs.