Effects of Basal Media and Supplements on Diethylstilbestrol-Treated Immature Mouse Primary Granulosa Cell Growth and Regulation of Steroidogenesis In Vitro

Follicular fluid HD-sevs-mir-128-3p is a key molecule in regulating bovine granulosa cells autophagy

Follicular fluid (FF) is rich in extracellular vesicles (EVs). EVs carries a variety of miRNA involved in regulating follicular development, the function of cells in follicles, primordial follicular formation, follicular recruitment and selection, follicular atresia, oocyte communication, granulosa cells (GCs) function and luteinization and other biological processes of follicular development. Previous studies in our laboratory have shown that bovine follicular fluid (bFF) high density-small extracellular vesicles (HD-sEVs)-miRNA was enriched in autophagy-related pathways. However, the mechanism of bFF EVs carrying miRNA regulating GCs autophagy is not clear. Thus, this study carried out a series of studies on the previous HD-sEVs sequencing data and miR-128-3p contained in bFF HD-sEVs. A total of 38 differentially expressed genes were detected by RNA-Seq after overexpression of miR-128-3p in bovine GCs (bGCs). Through cell transfection, Western blot (WB) and Immunofluorescence (IF), it was proved that overexpression of miR-128-3p could promote the expression of LC3 (microtubule-associated protein I light chain 3), inhibit p62, promote the number of autophagosome, promote the formation of autophagy lysosome and autophagy flow, and activate bGCs autophagy. MiR-128-3p inhibitor significantly inhibited the expression of LC3 and monodansylcadaverine (MDC) in bGCs, and promoted the expression of autophagy substrate p62, indicating that HD-sEVs-miR-128-3p could activate bGCs autophagy. In addition, through double luciferase assay, bioinformatics analysis, WB and RT-qPCR, it was concluded that bFF HD-sEVs-miR-128-3p could target TFEB (transcription factor EB) and FoxO4 (Forkhead box O4) and activate GCs autophagy.

NR5A1 and NR5A2 regulate follicle development in chicken (Gallus gallus) by altering proliferation, apoptosis, and steroid hormone synthesis of granulosa cells

Chicken ovarian follicle development is regulated by complex and dynamic gene expression. Nuclear receptor 5A1 and 5A2 (NR5A1 and NR5A2, respectively) are key genes that regulate steroid hormone production and gonadal development in mammals; however, studies on follicular development in the chicken ovary are scarce. In this study, we investigated the functions of NR5A1 and NR5A2 on follicle development in chickens. The results showed that the expression of NR5A1 and NR5A2 was significantly higher in small yellow follicles and F5. Furthermore, the expression of NR5A1 and NR5A2 was significantly higher in follicular tissues of peak-laying hens (30 wk) than in follicular tissues of late-laying hens (60 wk), with high expression abundance in granulosa cells (GC). The overexpression of NR5A1 and NR5A2 significantly promoted proliferation and inhibited apoptosis of cultured GC; upregulated STAR, CYP11A1, and CYP19A1 expression and estradiol (E2) and progesterone (P4) synthesis in GC from preovulatory follicles (po-GC); and increased STAR, CYP11A1, and CYP19A1 promoter activities. In addition, follicle-stimulating hormone treatment significantly upregulated NR5A1 and NR5A2 expression in po-GC and significantly promoted FSHR, CYP11A1, and HSD3B1 expression in GC from pre-hierarchical follicles and po-GC. The core promoter region of NR5A1 was identified at the -1,095- to -483-bp and -2,054- to -1,536-bp regions from the translation start site (+1), and the core promoter region of NR5A2 was at -998 to -489 bp. Two single nucleotide polymorphisms (SNP) were identified in the core promoter region of the NR5A1 gene, which differed between high- and low-yielding chicken groups. Our study suggested that NR5A1 and NR5A2 promoted chicken follicle development by promoting GC proliferation and E2 and P4 hormone synthesis and inhibiting apoptosis. Moreover, we identified the promoter core region or functional site that regulates NR5A1 and NR5A2 expression.

Cell- and Serum-Derived Proteins Act as DAMPs to Activate RAW 264.7 Macrophage-like Cells on Silicone Implants

Protein adsorption after biomaterial implantation is the first stage of the foreign body response (FBR). However, the source(s) of the adsorbed proteins that lead to damaged associated molecular patterns (DAMPs) and induce inflammation have not been fully elucidated. This study examined the effects of different protein sources, cell-derived (from a NIH/3T3 fibroblast cell lysate) and serum-derived (from fetal bovine serum), which were compared to implant-derived proteins (after a 30 min subcutaneous implantation in mice) on activation of RAW 264.7 cells cultured in minimal (serum-free) medium. Both cell-derived and serum-derived protein sources when preadsorbed to either tissue culture polystyrene or medical-grade silicone induced RAW 264.7 cell activation. The combination led to an even higher expression of pro-inflammatory cytokine genes and proteins. Implant-derived proteins on silicone explants induced a rapid inflammatory response that then subsided more quickly and to a greater extent than the studies with in vitro cell-derived or serum-derived protein sources. Proteomic analysis of the implant-derived proteins identified proteins that included cell-derived and serum-derived, but also other proteinaceous sources (e.g., extracellular matrix), suggesting that the latter or nonproteinaceous sources may help to temper the inflammatory response in vivo. These findings indicate that both serum-derived and cell-derived proteins adsorbed to implants can act as DAMPs to drive inflammation in the FBR, but other protein sources may play an important role in controlling inflammation.

Optimized culture system to maximize ovarian cell growth and functionality in vitro

Ovaries are the primary physiological source of female sex hormones, which play a crucial role in maintaining ovarian cycle, determining secondary sexual characteristics and preparing the endometrium for implantation. In vitro follicle engineering has been used to investigate follicle development, including ovarian hormone production and gamete maturation. To engineer functional follicles, culture and expansion of the primary ovarian cells are essential. However, the phenotypic and functional characteristics of primary ovarian cells are often lost during culture. The objective of this study is to develop an optimized culture system for maintaining ovarian cell growth and functionality. Granulosa cells (GCs) and theca cells (TCs) were isolated from female rats. The addition of follicle-stimulating hormone (FSH) or luteinizing hormone (LH) to the basal culture media significantly enhanced the secretion of estradiol from GCs and androstenedione from TCs. Serum concentrations of 5% and 10% had a similar role in promoting ovarian cell expansion and secretion of estradiol and androstenedione hormones from both types of cells. Growth differentiation factor 9 (GDF9), bone morphogenic protein 15 (BMP15), BMP7 and basic fibroblast growth factor (bFGF) enhanced GC proliferation and estradiol production, respectively. Among them, the effect of bFGF was most significant. bFGF also enhanced TC proliferation. When GCs and TCs were cultured in 5% serum, gonadotropin and bFGF-containing medium, they proliferated exponentially throughout the culture period of up to 40 days while maintaining their functional characteristics. Taken together, these results indicate that our medium formula is optimal for maximizing proliferation of functionally differentiated ovarian cells.

Effect of estrogen on chick primordial follicle development and activation

Steroid hormones and their receptors play pivotal roles in avian reproduction and development. 17β-estradiol (E₂ ) is an essential mediator in ovarian development. In this study, Day 3 (D3) chicks were injected with E₂ (0.025, 0.25 or 2.5 mg/kg body weight) for 4 days to assess the effects of estrogen on avian follicle development. Morphological analysis showed that treatment of E₂ at 2.5 mg/kg increased the number of growing follicles by 28. 5% and activated follicles by 8.9%, compared with the group. Treatment of E₂ also led to increased diameter and area of three kinds of follicles and oocytes, respectively. However, this stimulating effect of E₂ was inhibited by combined treatment of the estrogen receptor antagonist tamoxifen, resulting in decreased number of the growing follicles by 14.3% and the activated follicles by 5.8%, respectively. Immunohistochemical staining of the proliferating cell nuclear antigen (PCNA) revealed that the ratios of the PCNA-positive granulosa and interstitial cells were increased by 14.0% and 21.5%, respectively. Western blot analysis of PCNA confirmed this stimulating effect of E₂ . Expression of ERα mRNAs was elevated by administration of E₂ in vivo and in vitro. Furthermore, E- and N-cadherin displayed increased expression after E₂ treatment in vivo and in vitro. In conclusion, E₂ can promote chicken primordial follicle development and activation involving its increased receptor and cadherin production at the early stage of ovarian development.

Phosphodiesterases in the rat ovary: effect of cAMP in primordial follicles

Phosphodiesterases (PDEs) are important regulators of the intracellular cAMP concentration, which is a central second messenger that affects a multitude of intracellular functions. In the ovaries, cAMP exerts diverse functions, including regulation of ovulation and it has been suggested that augmented cAMP levels stimulate primordial follicle growth. The present study examined the gene expression, enzyme activity and immunolocalization of the different cAMP hydrolysing PDEs families in the rat ovary. Further, the effect of PDE4 inhibition on primordial follicle activation in cultured neonatal rat ovaries was also evaluated. We found varied expression of all eight families in the ovary with Pde7b and Pde8a having the highest expression each accounting for more than 20% of the total PDE mRNA. PDE4 accounted for 15-26% of the total PDE activity. Immunoreactive PDE11A was found in the oocytes and PDE2A in the corpora lutea. Incubating neonatal rat ovaries with PDE4 inhibitors did not increase primordial follicle activation or change the expression of the developing follicle markers Gdf9, Amh, Inha, the proliferation marker Mki67 or the primordial follicle marker Tmeff2. In addition, the cAMP analogue 8-bromo-cAMP did not increase AKT1 or FOXO3A phosphorylation associated with follicle activation or increase the expression of Kitlg known to be associated with follicle differentiation but did increase the Tmeff2, Mki67 and Inha expression in a dose-dependent manner. In conclusion, this study shows that both Pde7b and Pde8a are highly expressed in the rodent ovary and that PDE4 inhibition does not cause an increase in primordial follicle activation.

Insulin-transferrin-selenium as an alternative to foetal serum for epidermal equivalents

OBJECTIVE

Organotypic skin models are powerful tools for research in development, ageing and diseases. They have become more and more complex with the use of multiple cell types. This requires a culture medium adapted to optimize the development of such in vitro skin. Foetal bovine serum (FBS) is the most complete supplement in existence at the moment, providing at once growth factors, vitamins, hormones and other circulating compounds. However, this cocktail suffers from batch variability and its animal origin is ethically questionable. More importantly, its biological activities may interfere with the study of certain signalling pathways. Here, we present a strategy for constructing an epidermal equivalent using a defined culture medium without serum.

METHODS

An epidermal equivalent was constructed with primary human keratinocytes cultured using an insulin-transferrin-selenium (ITS) medium. Determination of steady-state gene expression levels and the immunohistological characterization of keratinocyte markers were performed to compare the ITS medium condition with a reference model, where keratinocytes were co-cultured with fibroblasts in the presence of FBS.

RESULTS

The data show that the ITS medium promoted the expression of keratinocyte proliferation and differentiation markers at the protein and transcript levels in a similar way to that of the reference model.

CONCLUSION

We show that culture using the ITS medium appears as a viable replacement for FBS in the construction of epidermal equivalents, opening the way to signal transduction studies.

Supplemented αMEM/F12-based medium enables the survival and growth of primary ovarian follicles encapsulated in alginate hydrogels

Hydrogel-encapsulating culture systems for ovarian follicles support the in vitro growth of secondary follicles from various species including mouse, non-primate human, and human; however, the growth of early stage follicles (primary and primordial) has been limited. While encapsulation maintains the structure of early stage follicles, feeder cell populations, such as mouse embryonic fibroblasts (MEFs), are required to stimulate growth and development. Hence, in this report, we investigated feeder-free culture environments for early stage follicle development. Mouse ovarian follicles were encapsulated within alginate hydrogels and cultured in various growth medium formulations. Initial studies employed embryonic stem cell medium formulations as a tool to identify factors that influence the survival, growth, and meiotic competence of early stage follicles. The medium formulation that maximized survival and growth was identified as αMEM/F12 supplemented with fetuin, insulin, transferrin, selenium, and follicle stimulating hormone (FSH). This medium stimulated the growth of late primary (average initial diameter of 80 µm) and early secondary (average initial diameter of 90 µm) follicles, which developed antral cavities and increased to terminal diameters exceeding 300 µm in 14 days. Survival ranged from 18% for 80 µm follicles to 36% for 90 µm follicles. Furthermore, 80% of the oocytes from surviving follicles with an initial diameter of 90-100 µm underwent germinal vesicle breakdown (GVBD), and the percentage of metaphase II (MII) eggs was 50%. Follicle/oocyte growth and GVBD/MII rates were not significantly different from MEF co-culture. Survival was reduced relative to MEF co-culture, yet substantially increased relative to the control medium that had been previously used for secondary follicles. Continued development of culture medium could enable mechanistic studies of early stage folliculogenesis and emerging strategies for fertility preservation.

CNP/NPR2 signaling maintains oocyte meiotic arrest in early antral follicles and is suppressed by EGFR-mediated signaling in preovulatory follicles

Oocyte meiosis is arrested at prophase I by factors secreted from surrounding somatic cells after oocytes acquire meiotic competence at an early antral stage, and meiosis resumes in preovulatory follicles as a result of the luteinizing hormone (LH) surge. Recently, signaling by C-type natriuretic peptide (CNP) through its receptor, natriuretic peptide receptor 2 (NPR2), was found to be essential for meiotic arrest at the late antral stage. Whether or not CNP/NPR2 signaling maintains oocyte meiotic arrest in earlier follicular stages and how it is associated with meiotic resumption induced by the LH surge is unclear. In this study, we examined the expression of Nppc and Npr2, respectively encoding CNP and NPR2, in the ovaries of immature mice. Nppc and Npr2 mRNA were specifically expressed in the outer and inner granulosa cell layers, respectively, in early antral follicles. Histological analysis of mice with a mutation in Npr2 revealed precocious resumption of oocyte meiosis in early antral follicles. Ovaries of mice treated with excess human chorionic gonadotropin (hCG) exhibited markedly decreased Nppc mRNA levels in granulosa cells of preovulatory follicles. Moreover, we found that amphiregulin, a mediator of LH/hCG activity through epidermal growth factor receptor (EGFR), suppressed Nppc mRNA levels in cultured granulosa cells. These results suggest that CNP/NPR2 signaling is essential for oocyte meiotic arrest in early antral follicles and that activated LH/amphiregulin/EGFR signaling pathway suppresses this signal by downregulating Nppc expression.