Depletion of substrates for protein prenylation increases apoptosis in human periovulatory granulosa cells

FSHR-mTOR-HIF1 signaling alleviates mouse follicles from AMPK-induced atresia

The majority of activated ovarian follicles undergo atresia during reproductive life in mammals, and only a small number of follicles are ovulated. Though hormone treatment has been widely used to promote folliculogenesis, the molecular mechanism behind follicle selection and atresia remains under debate due to inconsistency among investigation models. Using a high-throughput molecular pathology strategy, we depicted a transcriptional atlas of mouse follicular granulosa cells (GCs) under physiological condition and obtained molecular signatures in healthy and atresia GCs during development. Functional results revealed hypoxia-inducible factor 1 (HIF1) as a major effector downstream of follicle-stimulating hormone (FSH), and HIF1 activation is essential for follicle growth. Energy shortage leads to prevalent AMP-activated protein kinase (AMPK) activation and drives follicular atresia. FSHR-mTOR-HIF1 signaling helps follicles escape from the atresia fate, while energy stress persists. Our work provides a comprehensive understanding of the molecular network behind follicle selection and atresia under physiological condition.

Chronic Niche Inflammation in Endometriosis-Associated Infertility: Current Understanding and Future Therapeutic Strategies

Endometriosis is an estrogen-dependent inflammatory disease that affects up to 10% of women of reproductive age and accounts for up to 50% of female infertility cases. It has been highly associated with poorer outcomes of assisted reproductive technology (ART), including decreased oocyte retrieval, lower implantation, and pregnancy rates. A better understanding of the pathogenesis of endometriosis-associated infertility is crucial for improving infertility treatment outcomes. Current theories regarding how endometriosis reduces fertility include anatomical distortion, ovulatory dysfunction, and niche inflammation-associated peritoneal or implantation defects. This review will survey the latest evidence on the role of inflammatory niche in the peritoneal cavity, ovaries, and uterus of endometriosis patients. Nonhormone treatment strategies that target these inflammation processes are also included. Furthermore, mesenchymal stem cell-based therapies are highlighted for potential endometriosis treatment because of their immunomodulatory effects and tropism toward inflamed lesion foci. Potential applications of stem cell therapy in treatment of endometriosis-associated infertility in particular for safety and efficacy are discussed.

Simvastatin decreases steroid production in the H295R cell line and decreases steroids and FSH in female rats

Endocrine modulating effects of Simvastatin (SV) and its metabolite, Simvastatin β-hydroxy acid (SVA), were investigated in H295R cells and in female Sprague-Dawley (SPRD) rats. H295R cells were exposed to SV and SVA concentrations from 0 to 10μM for 48h. Four groups of SPRD rats received 0 (CT), 1.3 (L), 5.0 (M), and 20.0 (H)mg SV/kg bw/day for 14 days. 10 Steroids were investigated in H295R growth media, and in tissues and plasma from rats using GC-MS/MS. Plasma LH and FSH were quantified by ELISA. In the H295R assay, SV and SVA particularly decreased progestagens with IC50-values from 0.10-0.13μM for SV and from 0.019-0.055μM for SVA. In rats, SV decreased progestagens in ovaries, brain and plasma, and plasma FSH in the M (72.4% decrease) and H group (76.6% decrease). Because progestagens and gonadotropins are major players in fertility, administration of SV might exert negative effects on female reproduction.

Statins as Targeted "Magical Pills" for the Conservative Treatment of Endometriosis: May Potential Adverse Effects on Female Fertility Represent the "Dark Side of the Same Coin"? A Systematic Review of Literature

The aim of the study was to analyze all the available evidence from both in vitro and in vivo studies regarding the efficacy of statin therapy in the treatment of endometriosis, evaluating the potential efficacy, side effects, and contraindications of their administration in humans. We focused on defining the potential benefits that the administration of statins may have on patients affected by endometriosis and the possible adverse effects of such a therapy on ovarian function and fertility profile. According to our article selection criteria, we included in the review in vitro and in vivo studies performed on human or animal models. The systematic review of literature identified 24 eligible articles, 12 of which reported evidence regarding the effects of statins on endometrial/endometriotic cells and 12 regarding their effects on ovarian function and fertility. All articles seem to emphasize the utility of statin administration in the treatment of endometriosis due to their anti-proliferative/proapoptotic effects, their ability to reduce cell viability and migration, and the inhibition of angiogenesis and anti-inflammatory activities. Regarding the potential adverse effects on gonadal activities, steroidogenesis and fertility function, no conclusive data were collected in human models (excluding women affected by polycystic ovary syndrome in which significant decline of androgen levels was reported after statin treatment), while contrasting results were reported by studies conducted in in vitro and in vivo in animal models. Despite evidence supporting statins as the potential therapeutic agent for a targeted conservative treatment of endometriosis, the uncertainties regarding their impact on gonadal function may not define them as an appropriate therapy for all young fertile women.

Time dependent influence of etonogestrel on the caspase-3 immunoreactivity and apoptotic indexes of rat uterus and ovaries

Apoptosis is necessary for the balance between cell proliferation and loss. Thirty-six Wistar-Albino rats were subjected to investigate apoptotic effect of widely used implantable progestins on ovarian and uterine tissues. Rats were divided into 6 groups. In the first five groups, we applied etonogestrel (IMP) subcutaneous implants (n = 30). The rats in groups were sacrificed sequentially every 10 days after application. The rats in the last group (n = 6) were accepted as controls. Apoptotic index (AI) values and Caspase-3 immunoreactivities of ovaries and uterus were recorded. In IMP groups, AI and Hscore values in stroma and glandular epithelium of uterus, granulosa and teca-lutein cells of the ovary increased with the longer progesterone exposure. Increase in AI and Hscore values were more prominent after 30 days of exposure for teca-lutein cells of ovary. Progestins increased apoptosis in ovaries and uterus by the longer exposure. Apoptosis increased in ovaries by chronic progesterone exposure. The apoptotic effect of progestin on endometrium is clear but long-term systemic application may lead to alterations in ovarian physiology. We evaluated time dependent apoptotic effect of etonogestrel on reproductive physiology and discussed progestins effect from another point of view in this study.

Defect in mevalonate pathway induces pyroptosis in Raw 264.7 murine monocytes

The inhibition of mevalonate pathway by the aminobisphosphonate alendronate (ALD) has been previously associated with an augmented lipopolysaccharide-induced interleukin-1beta (IL-1β) secretion in monocytes, as demonstrated in an auto-inflammatory disease known as mevalonate kinase deficiency (MKD). In this study we investigated the effect of ALD + LPS on monocyte cell line (Raw 264.7) death. ALD strongly augmented LPS-induced programmed cell death (PCD) as well as IL-1β secretion in Raw murine monocytes, whereas necrosis was rather unaffected. ALD + LPS induced caspase-3 activation. Inhibition of IL-1β stimulation partially restored cell viability. These findings suggest that the inhibition of mevalonate pathway, together with a bacterial stimulus, induce a PCD partly sustained by the caspase-3-related apoptosis and partly by caspase-1-associated pyroptosis. The involvement of pyroptosis is a novel hit in our cell model and opens discussions about its role in inflammatory cells with chemical or genetic inhibition of mevalonate pathway.

The water permeability channels aquaporins 1-4 are differentially expressed in granulosa and theca cells of the preovulatory follicle during precise stages of human ovulation

CONTEXT

Changes in vascular permeability and expansion of the fluid-filled antrum are major events in the LH-induced ovulatory process.

OBJECTIVES

Our objective was to investigate the presence and expression levels of aquaporins (AQPs) in the granulosa and theca cell compartments of the follicle during defined phases of human ovulation.

DESIGN AND SETTING

We conducted a prospective experimental study at the Department of Obstetrics and Gynaecology at a university hospital.

PARTICIPANTS

Twenty-eight women underwent laparoscopic sterilization and at the same time follicle retrieval at four periovulatory phases.

MAIN OUTCOME MEASURES

mRNA levels of AQP1-4 were measured in separated granulosa and theca cells from preovulatory phase, early ovulatory (EO) phase, late ovulatory phase, and postovulatory phase. Immunohistochemistry was done for AQP1-4 in intact human follicles.

RESULTS

All four AQPs were expressed in both the theca and granulosa cells during ovulation. In granulosa cells, AQP1 levels increased in the late ovulatory and postovulatory phases. Expression of AQP2-3 followed a similar pattern with a marked increase in the EO phase, whereas AQP4 levels decreased from preovulatory to the EO phase. The presence of AQP1-4 in the human follicle was verified by immunohistochemistry.

CONCLUSIONS

The results show for the first time the presence of AQP1-4 in human follicles during ovulation. The marked early rise in expression of AQP2 and AQP3 suggests a role during the process leading to follicular rupture, and the late rise of AQP1 suggests a role in corpus luteum formation.

Mouse oocyte control of granulosa cell development and function: paracrine regulation of cumulus cell metabolism

Bidirectional communication between oocytes and the companion granulosa cells is essential for the development and functions of both compartments. Oocytes are deficient in their ability to transport certain amino acids and in carrying out glycolysis and cholesterol biosynthesis. Cumulus cells must provide them with the specific amino acids and the products in these metabolic pathways. Oocytes control metabolic activities in cumulus cells by promoting the expression of genes in cumulus cells encoding specific amino acid transporters and enzymes essential for the oocyte-deficient metabolic processes. Hence oocytes outsource metabolic functions to cumulus cells to compensate for oocyte metabolic deficiencies. Oocyte control of granulosa cell metabolism may also participate in regulating the rate of follicular development in coordination with endocrine, paracrine, and autocrine signals. Oocytes influence granulosa cell development mainly by secretion of paracrine factors, although juxtacrine signals probably also participate. Key oocyte-derived paracrine factors include growth differentiation factor 9, bone morphogenetic protein 15, and fibroblast growth factor 8B.

The effect of mifepristone on apoptosis and caspase-3 activation in human ovarian luteinized granulosa cells

OBJECTIVE

To investigate the effect of mifepristone, an oral contraceptive, on apoptosis in human ovarian luteinized granulosa cells.

STUDY DESIGN

Human ovarian luteinized granulosa cells were treated in vitro with 1.25, 2.5, 5.0, 10.0, or 20.0 microM of mifepristone. Nuclear morphology, apoptosis ratio, and level of caspase-3 expression were determined with immunofluorescence microscopy, the terminal deoxynucleotidyl transferase mediated nick end labeling (TUNEL) assay, and flow cytometry.

RESULTS

We found that mifepristone-treated cells contained single condensed chromatin with multiple nuclear fragments, which is morphologic evidence of apoptosis. A significant difference was observed in the TUNEL assay between mifepristone-treated cells and control cells (P<0.05). Consistent with the results of the TUNEL assay, the fluorescence intensity of caspase-3 in drug-treated cells was also significantly different (P<0.05) from control cells; specifically, the difference between cells treated with different doses of drugs was much smaller and negligible.

CONCLUSION

From these results, we propose that mifepristone induces human ovarian luteinized granulosa cells to undergo apoptosis by activating caspase-3.

Oocyte regulation of metabolic cooperativity between mouse cumulus cells and oocytes: BMP15 and GDF9 control cholesterol biosynthesis in cumulus cells

Oocyte-derived bone morphogenetic protein 15 (BMP15) and growth differentiation factor 9 (GDF9) are key regulators of follicular development. Here we show that these factors control cumulus cell metabolism, particularly glycolysis and cholesterol biosynthesis before the preovulatory surge of luteinizing hormone. Transcripts encoding enzymes for cholesterol biosynthesis were downregulated in both Bmp15(-/-) and Bmp15(-/-) Gdf9(+/-) double mutant cumulus cells, and in wild-type cumulus cells after removal of oocytes from cumulus-cell-oocyte complexes. Similarly, cholesterol synthesized de novo was reduced in these cumulus cells. This indicates that oocytes regulate cumulus cell cholesterol biosynthesis by promoting the expression of relevant transcripts. Furthermore, in wild-type mice, Mvk, Pmvk, Fdps, Sqle, Cyp51, Sc4mol and Ebp, which encode enzymes required for cholesterol synthesis, were highly expressed in cumulus cells compared with oocytes; and oocytes, in the absence of the surrounding cumulus cells, synthesized barely detectable levels of cholesterol. Furthermore, coincident with reduced cholesterol synthesis in double mutant cumulus cells, lower levels were also detected in cumulus-cell-enclosed double mutant oocytes compared with wild-type oocytes. Levels of cholesterol synthesis in double mutant cumulus cells and oocytes were partially restored by co-culturing with wild-type oocytes. Together, these results indicate that mouse oocytes are deficient in synthesizing cholesterol and require cumulus cells to provide products of the cholesterol biosynthetic pathway. Therefore, oocyte-derived paracrine factors, particularly, BMP15 and GDF9, promote cholesterol biosynthesis in cumulus cells, probably as compensation for oocyte deficiencies in cholesterol production.

Apoptotic effects of a progesterone receptor antagonist on rat granulosa cells are not mediated via reduced protein isoprenylation

Progesterone is a survival factor in rat periovulatory granulosa cells. The mechanisms involved are unclear but progesterone receptor (PGR) antagonists have been shown to inhibit cholesterol synthesis and induce apoptosis. Furthermore, reports suggest that statins induce apoptosis by inhibition of protein isoprenylation. Statins inhibit the rate-limiting step of the cholesterol synthesis, thereby reducing availability of intermediates used for the post-translational isoprenylation process. It has been suggested that PGR antagonists in a similar manner induce apoptosis by decreasing cholesterol synthesis and thereby protein isoprenylation. In this study we hypothesized that the mechanism by which the nuclear PGR antagonist Org 31,710 induces apoptosis in rat periovulatory granulosa cells, is by decreasing cholesterol synthesis and thereby general cell protein isoprenylation. Incubation of isolated granulosa cells with Org 31,710 or simvastatin for 22 hr resulted in increased apoptosis and reduced cholesterol synthesis. However, simvastatin caused a substantial inhibition of cholesterol synthesis after 6 hr in culture without inducing apoptosis. In contrast, Org 31,710 had only a modest effect on cholesterol synthesis after 6 hr while it significantly induced apoptosis. Addition of isoprenylation substrates partially reversed apoptosis induced by simvastatin and to a lesser extent apoptosis induced by Org 31,710. In addition, and in contrast to Org 31,710, simvastatin caused a decrease in isoprenylation of a selected isoprenylation marker protein, the Ras-related protein RAB11. In conclusion, we demonstrate that the PGR antagonist inhibits cholesterol synthesis in granulosa cells but reduced protein isoprenylation is not the mediating mechanism of increased apoptosis as previously hypothesized.