Molecular mechanisms of ovulation: co-ordination through the cumulus complex

FTO-mediated m6A modification elevates the MFN2 mRNA stability to suppress ovarian granulosa cell senescence

Although significant progress has been made in human-assisted reproductive technology in recent decades, fertility issues related to ovarian senescence remain a pressing challenge in reproductive medicine. As granulosa cells play a critical role in supporting oocytes, understanding the mechanisms of ovarian granulosa cell senescence is crucial to addressing the decline in ovarian function and oocyte quality associated with ovarian senescence. Previous studies have indicated that the mitochondrial fusion protein (MFN2) may play a key role in ovarian senescence and is linked to the outcomes of assisted reproductive technology. However, the precise underlying mechanism remains unclear. In this study, we found that the expression of MFN2 was significantly downregulated during ovarian granulosa cell senescence and that the overexpression of MFN2 delayed senescence. Moreover, N6-methyladenosine (m6A) modification and demethylase FTO were found to play important regulatory roles in this process. Mechanistically, we discovered that the demethylase FTO enhanced the stability of MFN2 mRNA in a YTH N6-methyladenosine RNA binding protein F2-dependent manner, thereby inhibiting granulosa cell senescence. These findings expand the epigenetic regulatory landscape of ovarian granulosa cell senescence and further confirm the significant role of FTO and m6A modifications in delaying this process. These findings provide new insights and molecular targets for diagnosing and treating ovarian senescence.

Temporal optimization of meiotic arrest for enhancing oocyte maturity during in vitro maturation of porcine median antral follicles

During in vitro maturation (IVM), median antral follicles (MAFs) were mechanically aspirated from the porcine ovarian cortex, and this process causes an early disconnection of follicular somatic cells from oocytes within antral follicles before the formation of graafian follicles. Thus, nuclear maturation is accelerated ahead of the completion of cytoplasmic maturation. Dibutyryl-cAMP (dbcAMP), a well-known cAMP modulator, is used to inhibit the resumption of meiosis in immature oocytes. However, there is no information on the optimal timeframe for sustaining meiotic arrest to enhance oocyte maturity during IVM. To determine the optimal duration of meiotic arrest, immature cumulus-oocyte complexes (COCs) from MAFs were cultured with 1 mM dbcAMP for 0, 4, 8, 12, 16, or 22 h, followed by further IVM without dbcAMP for 44, 40, 36, 32, 28, or 22 h. Subsequently, nuclear maturation, cumulus cell expansion score, perivitelline space size, glutathione (GSH) and reactive oxygen species (ROS) levels, and preimplantation development of parthenogenetic and in vitro-fertilized embryos were assessed in oocytes from each group. The results showed that a 16-h treatment with 1 mM dbcAMP within the 44-h IVM process yielded the highest oocyte maturity. Accordingly, we established an advanced IVM protocol for producing oocytes with superior maturity from porcine MAFs by achieving nuclear maturation 36 h after initiating IVM, using a 16-h treatment with 1 mM dbcAMP within the 44-h IVM process.

Change in the ability of bovine granulosa cells to elongate transzonal projections and their transcriptome changes during follicle development

Granulosa cells (GCs) in secondary follicles differentiate into cumulus cells (CCs) and mural granulosa cells (MGCs) in the antral follicle. Only CCs maintain direct connections with oocytes through transzonal projections (TZPs) and support oocyte growth. Here, we examined whether granulosa cells (GCs) from secondary follicles and MGCs from early and late antral follicles were able to reconstruct complexes with TZP-free denuded oocytes (DOs) and regenerate TZPs. Furthermore, to confirm that the regenerated TZPs were functional, the development of the reconstructed complexes and oocyte growth in the complexes were evaluated. After coculture, GCs and MGCs from early antral follicles reconstructed the complexes with DOs and regenerated TZPs. Furthermore, the oocytes in the integrally reconstructed complexes grew fully and acquired meiotic competence, suggesting that the regenerated TZPs were functional. In contrast, MGCs from the late antral follicles lost their ability to elongate TZPs. As the ability to regenerate TZPs differed among cells, we analyzed the transcriptomes of GCs, CCs, and MGCs collected from follicles of different sizes. The characteristics of TZP generation coincided with the transcriptome changes in two directions: from GCs to CCs and MGCs. In conclusion, until the early antral follicle stage, bovine GCs, CCs, and MGCs have common characteristics to elongate TZPs and form antrum-like structures that support oocyte growth in vitro. Furthermore, as the follicle develops, MGCs lose the ability to elongate TZPs.

Effect of intrafollicular administration of PGE2 or PGF2α in early estrus on ovulation, hemorrhagic anovulatory follicles formation, progesterone secretion and pregnancy outcome in the mare

This experiment was performed to evaluate whether intrafollicular treatment of PGE2 or PGF2α administered in early estrus would induce normal ovulation, progesterone production (Experiment 1) and pregnancy (Experiment 2). In Experiment 1, mares in estrus after 2 days of endometrial edema were injected in all largest dominant follicles (28-35 mm in diameter) with 0.5 mL of sterile water containing 500 μg PGE2 (n = 6), 125 μg PGF2α (n = 6) or placebo (n = 7) (Hour 0). Ultrasound examinations were performed daily, until ovulation or anovulation was detected, and daily blood samples were taken for 8 days. In Experiment 2, mares with a dominant follicle ≥35 mm after at least three days of slight-to-moderate endometrial edema, were injected with 500 μg PGE2 diluted in 0.5 mL of sterile water for injection in the follicle (PGE2 group; n = 9 mares and 11 dominant follicles). No puncture was performed in the control group (n = 9 mares and 11 dominant follicles). Mares from both groups were inseminated. In Experiment 1, all mares (6/6) in the PGE2 group ovulated within 24 h of treatment. The mean interval from intrafollicular injection to ovulation was shorter (P < 0.001) in PGE2 mares (24 ± 0 h) than in control mares (77 ± 9 h). Mares from the PGF2α group developed hemorrhagic anovulatory follicles (HAF) more often (7/7) than control mares (2/7); P < 0.05). The progesterone concentration in mares from the PGF2α group was lower (P < 0.004) than control mares in the early post-ovulatory period. The first significant increase in post-ovulatory progesterone concentration occurred earlier (P < 0.05) in mares from the control group than in mares from the PGF2α and PGE2 groups. In Experiment 2, more mares from the control group (7/9, 78 %) became pregnant than from the PGE2 group (2/9, 22 %) (P = 0.015). In conclusion, PGE2 alone induced follicle collapse in all treated mares within 24 h of administrations, while PGF2α blocked ovulation and induced formation of HAFs. However, the post-ovulatory rise in progesterone production was delayed and the fertility reduced in mares with ovulation induced by PGE2 compared to control mares.

Ex vivo imaging reveals the spatiotemporal control of ovulation

During ovulation, an egg is released from an ovarian follicle, ready for fertilization. Ovulation occurs inside the body, impeding direct studies of its progression. Therefore, the exact mechanisms that control ovulation have remained unclear. Here we devised live imaging methods to study the entire process of ovulation in isolated mouse ovarian follicles. We show that ovulation proceeds through three distinct phases, follicle expansion (I), contraction (II) and rupture (III), culminating in the release of the egg. Follicle expansion is driven by hyaluronic acid secretion and an osmotic gradient-directed fluid influx into the follicle. Then, smooth muscle cells in the outer follicle drive follicle contraction. Follicle rupture begins with stigma formation, followed by the exit of follicular fluid and cumulus cells and the rapid release of the egg. These results establish a mechanistic framework for ovulation, a process of fundamental importance for reproduction.

Follicle-intrinsic and spatially distinct molecular programs drive follicle rupture and luteinization during ex vivo mammalian ovulation

During ovulation, the apical wall of the preovulatory follicle breaks down to facilitate gamete release. In parallel, the residual follicle wall differentiates into a progesterone-producing corpus luteum. Disruption of ovulation, whether through contraceptive intervention or infertility, has implications for women's health. In this study, we harness the power of an ex vivo ovulation model and machine-learning guided microdissection to identify differences between the ruptured and unruptured sides of the follicle wall. We demonstrate that the unruptured side exhibits clear markers of luteinization after ovulation while the ruptured side exhibits cell death signals. RNA-sequencing of individual follicle sides reveals 2099 differentially expressed genes (DEGs) between follicle sides without ovulation induction, and 1673 DEGs 12 h after induction of ovulation. Our model validates molecular patterns consistent with known ovulation biology even though this process occurs in the absence of the ovarian stroma, vasculature, and immune cells. We further identify previously unappreciated pathways including amino acid transport and Jag-Notch signaling on the ruptured side and glycolysis, metal ion processing, and IL-11 signaling on the unruptured side of the follicle. This study yields key insights into follicle-inherent, spatially-defined pathways that underlie follicle rupture, which may further understanding of ovulation physiology and advance women's health.

Protease expression in the human and rat cumulus-oocyte complex during the periovulatory period: a role in cumulus-oocyte complex migration†

The migratory and matrix-invading capacities of the cumulus-oocyte complex have been shown to be important for the ovulatory process. In metastatic cancers, these capacities are due to increased expression of proteases, however, there is limited information on protease expression in the cumulus-oocyte complexes. The present study examined cumulus-oocyte complex expression of plasmins, matrix metalloproteases, and A Disintegrin and Metalloproteinase with Thrombospondin Motifs family members in the rat and human. In the rat, human chorionic gonadotropin (hCG) administration increased cumulus-oocyte complex expression of Mmp2, Mmp9, Mmp13, Mmp14, Mmp16, Adamts1, and the protease inhibitors Timp1, Timp3, and Serpine1 by 8-12 h. This ovulatory induction of proteases in vivo could be mimicked by forskolin and ampiregulin treatment of cultured rat cumulus-oocyte complexes with increases observed in Mmp2, Mmp13, Mmp14, Mmp16, Mmp19, Plat, and the protease inhibitors Timp1, Timp3, and Serpine1. Comparison of expression between rat cumulus-oocyte complexes and granulosa cells at the time of ovulation showed decreased Mmp9 and increased Mmp13, Mmp14, Mmp16, Adamts1, Timp1, and Timp3 expression in the cumulus-oocyte complexes. In human, comparison of expression between cumulus and granulosa cells at the time of in vitro fertilization retrieval showed decreased MMP1, MMP2, MMP9, and ADAMTS1, while expression of MMP16, TIMP1, and TIMP3 were increased. Treatment of expanding rat cumulus-oocyte complexes with a broad spectrum matrix metalloproteases inhibitor, GM6001, significantly reduced the migration of cumulus cells in vitro. These data provide evidence that multiple proteases and their inhibitors are expressed in the cumulus-oocyte complex and play an important role in imparting the migratory phenotype of the cumulus-oocyte complex at the time of ovulation. Summary Sentence  Multiple proteases and their inhibitors are induced in the cumulus-oocyte complex (COC) during the periovulatory period and potentially play an important role in imparting the migratory phenotype of the COC at the time of ovulation.

Quantitative label-free proteomic analysis of mouse ovarian antral follicles following oral exposure to a human-relevant mixture of three phthalates

Dibutyl phthalate (DBP), di-2-ethylhexyl phthalate (DEHP), and benzyl butyl phthalate (BBP) are used in personal and medical care products. In the ovary, antral follicles are essential for steroidogenesis and ovulation. DBP, BBP, and DEHP are known to inhibit mouse antral follicle growth and ovulation in vitro, and associate with decreased antral follicle counts in women. Given that the in vivo effects of a three-phthalate mixture on antral follicles are unknown, we evaluated the effects of a human-relevant mixture of DBP, BBP, and DEHP on ovarian follicles through proteome profiling analysis. Adult CD-1 female mice were fed corn oil (vehicle), or two dose levels of a phthalate mixture based on estimated exposures in general (32 µg/kg/d; PHT 32) and occupationally exposed (500 µg/kg/d; PHT 500) populations for 10 d. Antral follicles (>250 µm) were isolated and subjected to proteome profiling via label-free tandem mass spectrometry. A total of 5,417 antral follicle proteins were detected, of which 194 were differentially abundant between vehicle and PHT 32, and 136 between vehicle and PHT 500. Bioinformatic analysis revealed significantly different responses between the two phthalate doses. Protein abundance differences in the PHT 32 exposure mapped to cytoplasm, mitochondria, and lipid metabolism; whereas those in the PHT 500 exposure mapped to cytoplasm, nucleus, and phosphorylation. When both doses altered proteins mapped to common processes, the associated predicted transcription factors were different. These findings provide novel mechanistic insight into phthalate-associated, ovary-driven reproductive outcomes in women.

Ketoconazole blocks progesterone production without affecting other parameters of cumulus-oocyte complex maturation

Ketoconazole (KTZ) is widely used as a fungicide, but it is also known to target steroid hormone formation which may affect female reproductive health. Our study aims to investigate the effects of KTZ on in vitro matured bovine cumulus-oocyte complexes (COCs), as a model for female reproductive toxicity. Cumulus cells of in vitro maturing COCs produce progesterone and pregnenolone, but exposure to 10-6 M KTZ effectively blocked the synthesis of these hormones. Exposure to lower concentrations of KTZ (i.e. 10-7 M and 10-8 M) had no such effect on steroidogenesis compared to the 0.1 % v/v DMSO vehicle control. Classical parameters of in vitro COC maturation, such as oocyte nuclear maturation to the metaphase II stage and expansion of the cumulus investment, were not affected by any KTZ concentration tested. Apoptosis and necrosis levels were also not altered in cumulus cells or oocytes exposed to KTZ. Moreover, oocytes exposed to KTZ during maturation showed normal cleavage and early embryo development up to day 8 post fertilization; albeit a statistically significant decrease was observed in day 8 blastocysts produced from oocytes exposed to the lowest concentration of 10-8 M KTZ. When unexposed mature oocytes were fertilized, followed by embryo culture for 8 days under KTZ exposure, no adverse effects in embryo cleavage and blastocyst formation were observed. In conclusion, KTZ has no major impact on in vitro bovine oocyte maturation and blastocyst formation in our study, even at concentrations blocking steroidogenesis.

GnRH agonist-only trigger, compared to dual trigger, reduces oocyte retrieval rate in high responders without affecting cumulative live birth rate

Introduction

This study compared, in high responders undergoing IVF treatment, GnRH agonist-only trigger and dual trigger on oocyte retrieval rate and cumulative live birth rate (LBR). The aim was to determine if the GnRH agonist-only triggers had provided outcomes comparable to dual trigger, while minimizing the risk of ovarian hyperstimulation syndrome (OHSS).

Materials and methods

A retrospective, matched case-control study was conducted at Taichung Veterans General Hospital, Taiwan, including women who underwent IVF/ICSI between January 1, 2014, and December 31, 2022. Inclusion criteria were: GnRH antagonist protocol and estrogen level >3,000 pg/ml on trigger day. Exclusion criteria were: immune/metabolic diseases, donated oocytes, and mixed stimulation cycles. Propensity score matching was applied to balance age, AMH level, and oocyte number between the GnRH agonist-only and dual trigger groups. Outcomes were analyzed for patients who had complete treatment cycles, focusing on oocyte retrieval rate and cumulative LBR.

Results

We analyzed 116 cycles in the agonist-only group, and 232 cycles in the dual trigger group. No inter-group difference was found in their age, BMI, and AMH levels. The dual trigger group had a higher oocyte retrieval rate (93% vs. 80%; p <0.05), while fertilization rates, blastocyst formation rates, and cumulative LBR were comparable. Notably, no OHSS cases had been reported in the GnRH agonist-only group, compared with 7 cases in the dual trigger group.

Conclusion

GnRH agonist-only triggers resulted in a lower oocyte retrieval rate compared to dual triggers but did not significantly affect cumulative LBR in high responders. This approach effectively reduces OHSS risk without compromising pregnancy outcomes, making it a preferable option in freeze-all strategies, despite a longer oocyte pick-up duration and a medium cost. GnRH agonist-only trigger, however, may not be suitable for fresh embryo transfers or patients with low serum LH levels on trigger day.

Three-Dimensionally Printed Agarose Micromold Supports Scaffold-Free Mouse Ex Vivo Follicle Growth, Ovulation, and Luteinization

Ex vivo follicle growth is an essential tool, enabling interrogation of folliculogenesis, ovulation, and luteinization. Though significant advancements have been made, existing follicle culture strategies can be technically challenging and laborious. In this study, we advanced the field through development of a custom agarose micromold, which enables scaffold-free follicle culture. We established an accessible and economical manufacturing method using 3D printing and silicone molding that generates biocompatible hydrogel molds without the risk of cytotoxicity from leachates. Each mold supports simultaneous culture of multiple multilayer secondary follicles in a single focal plane, allowing for constant timelapse monitoring and automated analysis. Mouse follicles cultured using this novel system exhibit significantly improved growth and ovulation outcomes with comparable survival, oocyte maturation, and hormone production profiles as established three-dimensional encapsulated in vitro follicle growth (eIVFG) systems. Additionally, follicles recapitulated aspects of in vivo ovulation physiology with respect to their architecture and spatial polarization, which has not been observed in eIVFG systems. This system offers simplicity, scalability, integration with morphokinetic analyses of follicle growth and ovulation, and compatibility with existing microphysiological platforms. This culture strategy has implications for fundamental follicle biology, fertility preservation strategies, reproductive toxicology, and contraceptive drug discovery.

Reproductive toxicity of PFOA, PFOS and their substitutes: A review based on epidemiological and toxicological evidence

Per- and polyfluoroalkyl substances (PFAS) have already drawn a lot of attention for their accumulation and reproductive toxicity in organisms. Perfluorooctanoic acid (PFOA) and perfluorooctanoic sulfonate (PFOS), two representative PFAS, are toxic to humans and animals. Due to their widespread use in environmental media with multiple toxicities, PFOA and PFOS have been banned in numerous countries, and many substitutes have been produced to meet market requirements. Unfortunately, most alternatives to PFOA and PFOS have proven to be cumulative and highly toxic. Of the reported multiple organ toxicities, reproductive toxicity deserves special attention. It has been confirmed through epidemiological studies that PFOS and PFOA are not only associated with reduced testosterone levels in humans, but also with an association with damage to the integrity of the blood testicular barrier. In addition, for women, PFOA and PFOS are correlated with abnormal sex hormone levels, and increase the risk of infertility and abnormal menstrual cycle. Nevertheless, there is controversial evidence on the epidemiological relationship that exists between PFOA and PFOS as well as sperm quality and reproductive hormones, while the evidence from animal studies is relatively consistent. Based on the published papers, the potential toxicity mechanisms for PFOA, PFOS and their substitutes were reviewed. For males, PFOA and PFOS may produce reproductive toxicity in the following five ways: (1) Apoptosis and autophagy in spermatogenic cells; (2) Apoptosis and differentiation disorders of Leydig cells; (3) Oxidative stress in sperm and disturbance of Ca2+ channels in sperm membrane; (4) Degradation of delicate intercellular junctions between Sertoli cells; (5) Activation of brain nuclei and shift of hypothalamic metabolome. For females, PFOA and PFOS may produce reproductive toxicity in the following five ways: (1) Damage to oocytes through oxidative stress; (2) Inhibition of corpus luteum function; (3) Inhibition of steroid hormone synthesis; (4) Damage to follicles by affecting gap junction intercellular communication (GJIC); (5) Inhibition of placental function. Besides, PFAS substitutes show similar reproductive toxicity with PFOA and PFOS, and are even more toxic to the placenta. Finally, based on the existing knowledge, future developments and direction of efforts in this field are suggested.

Berberine alleviates inflammation in polycystic ovary syndrome by inhibiting hyaluronan synthase 2 expression

BACKGROUND

Polycystic ovary syndrome (PCOS) is a heterogeneous metabolic and endocrine disorder that causes anovulatory infertility and abnormal folliculogenesis in women of reproductive age. Several studies have revealed inflammation in PCOS follicles, and recent evidence suggests that Berberine (BBR) effectively reduces inflammatory responses in PCOS, however, the underlying mechanisms remain unclear.

PURPOSE

To determine the underlying mechanisms by which BBR alleviates inflammation in PCOS.

STUDY DESIGN

Primary human GCs from healthy women and women with PCOS, and KGN cells were used for in vitro studies. ICR mice were used for in vivo studies.

METHODS

Gene expression was measured using RT-qPCR. HAS2, inflammatory cytokines, and serum hormones were assayed by ELISA. Protein expression profiles were assayed by Western blot. Chronic low-grade inflammatory mouse models were developed by intraperitoneal injection with LPS, and PCOS mouse models were established by subcutaneous intraperitoneal injection of DHEA. BBR and 4-MU were administered by gavage. Ovarian morphologic changes were evaluated using H&E staining. HAS2 expression in the ovary was assayed using Western blot and immunohistochemistry.

RESULTS

Our results confirmed that HAS2 expression and hyaluronan (HA) accumulation are closely associated with inflammatory responses in PCOS. Data obtained from in vitro studies showed that HAS2 and inflammatory genes (e.g., MCP-1, IL-1β, and IL-6) are significantly upregulated in PCOS samples and LPS-induced KGN cells compared to their control groups. In addition, these effects were reversed by blocking HAS2 expression or HA synthesis using BBR or 4-MU, respectively. Furthermore, HAS2 overexpression induces the expression of inflammatory genes in PCOS. These results were further confirmed in LPS- and DHEA-induced mouse models, where inflammatory genes were reduced by BBR or 4-MU, and ovarian morphology was restored.

CONCLUSIONS

Our results define previously unknown links between HAS2 and chronic low-grade inflammation in the follicles of women with PCOS. BBR exerts its anti-inflammatory effects by down-regulating HAS2. This study provides a novel therapeutic target for alleviating ovarian inflammation in women with PCOS.

Electro-Metabolic Coupling of Cumulus-Oocyte Complex

Oocyte-cumulus cell interaction is essential for oocyte maturation and competence. The bidirectional crosstalk network mediated by gap junctions is fundamental for the metabolic cooperation between these cells. As cumulus cells exhibit a more glycolytic phenotype, they can provide metabolic substrates that the oocyte can use to produce ATP via oxidative phosphorylation. The impairment of mitochondrial activity plays a crucial role in ovarian aging and, thus, in fertility, determining the success or failure of assisted reproductive techniques. This review aims to deepen the knowledge about the electro-metabolic coupling of the cumulus-oocyte complex and to hypothesize a putative role of potassium channel modulators in order to improve fertility, promote intracellular Ca2+ influx, and increase the mitochondrial biogenesis and resulting ATP levels in cumulus cells.

Transcriptomic signature of luteinized cumulus cells of oocytes developing to live birth after women received intracytoplasmic sperm injection

OBJECTIVE

To compare the transcriptome of human cumulus cells (CCs) from oocytes with different outcomes (pregnancy yes/no, live birth [LB] yes/no), to identify noninvasive biomarkers for oocyte selection as well as new therapeutic targets to increase LB rates from assisted reproductive technologies (ART).

DESIGN

Retrospective observational study.

SETTINGS

This study was conducted at a University Hospital in Switzerland.

PATIENTS

Subfertile couples undergoing controlled ovarian superstimulation and intracytoplasmic sperm injection with subsequent unbiopsied embryo transfer below the female age of 43 years.

INTERVENTION(S)

RNA sequencing of CCs from oocytes results in a pregnancy, no pregnancy, LB, or no LB.

MAIN OUTCOME MEASURES

Differential gene expression (DEG) between CCs of oocytes results in "no pregnancy" vs. "pregnancy" and "pregnancy only" vs. "live birth."

RESULTS

Although RNA sequencing did not reveal DEGs when comparing the transcriptomic profiles of the groups "no pregnancy" with "pregnancy," we identified 139 DEGs by comparing "pregnancy only" with "live birth," of which 28 belonged to clusters relevant to successful ART outcomes (i.e., CTGF, SERPINE2, PCK1, HHIP, HS3ST, and BIRC5). A functional enrichment analysis revealed that the transcriptome of CCs associated with LB depicts pathways of extracellular matrix, inflammatory cascades leading to ovulation, cell patterning, proliferation, and differentiation, and silencing pathways leading to apoptosis.

CONCLUSION

We identified a CCs transcriptomic profile associated with LB after embryo transfer that, after further validation, could serve to predict successful ART outcomes. The definition of relevant pathways of CCs related to oocyte competency contributes to a broader understanding of the cumulus oocyte complex and helps identify further therapeutic targets for improving ART success.

Impact of endometriosis on the ovarian follicles

A significant body of evidence has supported a negative impact of endometriosis on ovarian follicles; however, the origin and relevance of this ovarian impairment in endometriosis is still a matter of debate. The ovarian damage can be caused by endometriosis itself or by surgeries aiming to remove endometriotic lesions. In this review, we summarized the existing knowledge on the mechanisms by which endometriosis can impact the ovarian follicles, from molecular to clinical points of view. From a molecular standpoint, the presence of endometriosis or its consequences can induce oxidative stress, inflammation, aberrant mitochondrial energy metabolism and inappropriate steroid production in granulosa cells, phenomena that may impair the quality of oocytes to variable degrees. These alterations may have clinical relevance on the accelerated exhaustion of the ovarian reserve, on the ovarian response to gonadotrophin stimulation in IVF cycles and on the competence of the oocytes. Critical points to be considered in current clinical practices related to fertility issues in endometriosis are discussed.

Three-dimensional glass scaffolds improve the In Vitro maturation of porcine cumulus-oocyte complexes and subsequent embryonic development after parthenogenetic activation

In vitro maturation (IVM) methods for porcine oocytes are still deficient in achieving full developmental capacity, as the currently available oocyte in vitro culture systems still have limitations. In vitro embryo production must also improve the porcine oocyte IVM system to acquire oocytes with good developmental potential. Herein, we tested a three-dimensional (3D) glass scaffold culture system for porcine oocyte maturation. After 42 h, we matured porcine cumulus-oocyte complexes (COCs) on either two-dimensional glass dishes (2D-B), two-dimensional microdrops (2D-W), or 3D glass scaffolds. The 3D glass scaffolds were tested for porcine oocyte maturation and embryonic development. Among these culture methods, the extended morphology of the 3D group maintained a 3D structure better than the 2D-B and 2D-W groups, which had flat COCs that grew close to the bottom of the culture vessel. The COCs of the 3D group had a higher cumulus expansion index and higher first polar body extrusion rate, cleavage rate, and blastocyst rate of parthenogenetic embryos than the 2D-B group. In the 3D group, the cumulus-expansion-related gene HAS2 and anti-apoptotic gene Bcl-2 were significantly upregulated (p < 0.05), while the pro-apoptotic gene Caspase3 was significantly downregulated (p < 0.05). The blastocysts of the 3D group had a higher relative expression of Bcl-2, Oct4, and Nanog than the other two groups (p < 0.05). The 3D group also had a more uniform distribution of mitochondrial membrane potential and mitochondria (p < 0.05), and its cytoplasmic active oxygen species content was much lower than that in the 2D-B group (p < 0.05). These results show that 3D glass scaffolds dramatically increased porcine oocyte maturation and embryonic development after parthenogenetic activation, providing a suitable culture model for porcine oocytes.

A spatiotemporal molecular atlas of the ovulating mouse ovary

Ovulation is essential for reproductive success, yet the underlying cellular and molecular mechanisms are far from clear. Here, we applied high-resolution spatiotemporal transcriptomics to map out cell type- and ovulation stage-specific molecular programs as function of time during follicle maturation and ovulation in mice. Our analysis revealed dynamic molecular transitions within granulosa cell types that occur in tight coordination with mesenchymal cell proliferation. We identified molecular markers for the emerging cumulus cell fate during the preantral-to-antral transition. We describe transcriptional programs that respond rapidly to ovulation stimulation and those associated with follicle rupture, highlighting the prominent roles of apoptotic and metabolic pathways during the final stages of follicle maturation. We further report stage-specific oocyte-cumulus cell interactions and diverging molecular differentiation in follicles approaching ovulation. Collectively, this study provides insights into the cellular and molecular processes that regulate mouse ovarian follicle maturation and ovulation with important implications for advancing therapeutic strategies in reproductive medicine.

Downregulation of homeobox A1 in human granulosa cells is involved in diminished ovarian reserve through promoting cell apoptosis and mitochondrial dysfunction

Granulosa cell apoptosis contributes to the occurrence of diminished ovarian reserve (DOR). HOXA1, belonging to the HOX gene family, is involved in regulating cancer cell apoptosis. However, whether HOXA1 participates in the granulosa cell apoptosis in DOR patients remains to be elucidated. In the current study, we demonstrated the differential transcriptomic landscape of granulosa cells in DOR patients compared to that in the controls and identified decreased expression of the HOXA1 gene. Meanwhile, we found that HOXA1 was a gonadotropin-response gene, in which FSH could promote its expression, whereas LH inhibited HOXA1 expression in human granulosa cells. CCK-8 assay, flow cytometry and TUNEL staining results showed that inhibition of endogenous HOXA1 expression promoted human granulosa cell apoptosis. Moreover, knockdown of HOXA1 increased Bax while reducing Bcl2 protein expression. Furthermore, we found a total of 947 differentially expressed genes (DEGs), including 426 upregulated genes and 521 downregulated genes using transcriptome sequencing technology. Enrichment analysis results showed that the DEGs were involved in apoptosis and mitochondrial function-related signaling pathways. Knockdown of HOXA1 impaired mitochondrial functions, exhibiting increased reactive oxygen species (ROS) and cytoplasmic Ca2+ levels, decreased mitochondrial membrane potential, ATP production and mitochondrial DNA (mtDNA) copy number, and abnormal mitochondrial cristae. Our findings demonstrated that aberrantly reduced HOXA1 expression induced granulosa cell apoptosis in DOR patients and impaired mitochondrial function, which highlighted the potential role of HOXA1 in the occurrence of DOR and provided new insight for the treatment of DOR.

Transcriptomic integrity of human oocytes used in ARTs: technical and intrinsic factor effects

BACKGROUND

Millions of children have been born throughout the world thanks to ARTs, the harmlessness of which has not yet been fully demonstrated. For years, efforts to evaluate the specific effects of ART have focused on the embryo; however, it is the oocyte quality that mainly dictates first and foremost the developmental potential of the future embryo. Ovarian stimulation, cryopreservation, and IVM are sometimes necessary steps to obtain a mature oocyte, but they could alter the appropriate expression of the oocyte genome. Additionally, it is likely that female infertility, environmental factors, and lifestyle have a significant influence on oocyte transcriptomic quality, which may interfere with the outcome of an ART attempt.

OBJECTIVE AND RATIONALE

The objective of this review is to identify transcriptomic changes in the human oocyte caused by interventions specific to ART but also intrinsic factors such as age, reproductive health issues, and lifestyle. We also provide recommendations for future good practices to be conducted when attempting ART.

SEARCH METHODS

An in-depth literature search was performed on PubMed to identify studies assessing the human oocyte transcriptome following ART interventions, or in the context of maternal aging, suboptimal lifestyle, or reproductive health issues.

OUTCOMES

ART success is susceptible to external factors, maternal aging, lifestyle factors (smoking, BMI), and infertility due to endometriosis or polycystic ovary syndrome. Indeed, all of these are likely to increase oxidative stress and alter mitochondrial processes in the foreground. Concerning ART techniques themselves, there is evidence that different ovarian stimulation regimens shape the oocyte transcriptome. The perturbation of processes related to the mitochondrion, oxidative phosphorylation, and metabolism is observed with IVM. Cryopreservation might dysregulate genes belonging to transcriptional regulation, ubiquitination, cell cycle, and oocyte growth pathways. For other ART laboratory factors such as temperature, oxygen tension, air pollution, and light, the evidence remains scarce. Focusing on genes involved in chromatin-based processes such as DNA methylation, heterochromatin modulation, histone modification, and chromatin remodeling complexes, but also genomic imprinting, we observed systematic dysregulation of such genes either after ART intervention or lifestyle exposure, as well as due to internal factors such as maternal aging and reproductive diseases. Alteration in the expression of such epigenetic regulators may be a common mechanism linked to adverse oocyte environments, explaining global transcriptomic modifications.

WIDER IMPLICATIONS

Many IVF factors and additional external factors have the potential to impair oocyte transcriptomic integrity, which might not be innocuous for the developing embryo. Fortunately, it is likely that such dysregulations can be minimized by adapting ART protocols or reducing adverse exposure.

Bone morphogenetic protein 6 induces downregulation of pentraxin 3 expression in human granulosa lutein cells in women with polycystic ovary syndrome

PURPOSE

To evaluate whether PTX3 is differentially expressed in the granulosa lutein cells derived from women with PCOS and whether BMP6 can regulate the expression of PTX3 in hGL cells.

METHODS

The expression levels of BMP6 and PTX3 in granulosa lutein cells were evaluated by RT-qPCR. The correlation between the expression levels of BMP6 /PTX3 and oocyte quality indexes were analyzed using clinical samples. The cells were incubated with BMP6 at different concentrations and times to check the expression of PTX3 in KGN cells. TGF-β type I inhibitors and small interfering RNA targeting ALK2/3/6,SMAD1/5/8 and SMAD4 were used to study the involvement of SMAD dependent pathways in KGN cells.

RESULTS

The levels of BMP6 in hGL cells were negatively correlated with the corresponding oocyte maturation rate and high-quality embryo rate, whereas the levels of PTX3 were positively correlated with the corresponding oocyte maturation rate in PCOS. Additionally, the in vitro cell cultured results showed BMP6 significantly inhibited the expression of PTX3 in KGN cells. Furthermore, using a dual inhibition approach (kinase inhibitors and small interfering RNAs), we identified the ALK2/ALK3 type I receptors and BMPR2/ACVR2A type II receptors and the downstream SMAD1/SMAD5-SMAD4 signaling pathway were responsible for the BMP6-induced cellular activities in KGN cells.

CONCLUSIONS

The suppressive effect of BMP6 on PTX3 was mediated by ALK2/ALK3 type I receptors and BMPR2/ACVR2A type II receptors in granulosa cells through the SMAD1/5-SMAD4 dependent signaling pathway in PCOS.Our findings provides new insights into the understanding of the pathogenesis of PCOS-related ovulatory disorders.

Roles of immune microenvironment in the female reproductive maintenance and regulation: novel insights into the crosstalk of immune cells

Female fertility decline is an accumulative consequence caused by complex factors, among them, the disruption of the immune profile in female reproduction stands out as a crucial contributor. Presently, the effects of immune microenvironment (IME) on the female reproductive process have attracted increasing attentions for their dynamic but precisive roles. Immunocytes including macrophages, dendritic cells, T cells, B cells and neutrophils, with diverse subpopulations as well as high plasticity functioned dynamically in the process of female reproduction through indirect intercellular communication via specific cytokine release transduced by molecular signal networks or direct cell-cell contact to maintain the stability of the reproductive process have been unveiled. The immune profile of female reproduction in each stage has also been meticulously unveiled. Especially, the application of single-cell sequencing (scRNA-seq) technology in this process reveals the distribution map of immune cells, which gives a novel insight for the homeostasis of IME and provides a research direction for better exploring the role of immune cells in female reproduction. Here, we provide an all-encompassing overview of the latest advancements in immune modulation within the context of the female reproductive process. Our approach involves structuring our summary in accordance with the physiological sequence encompassing gonadogenesis, folliculogenesis within the ovaries, ovulation through the fallopian tubes, and the subsequent stages of embryo implantation and development within the uterus. Our overarching objective is to construct a comprehensive portrayal of the immune microenvironment (IME), thereby accentuating the pivotal role played by immune cells in governing the intricate female reproductive journey. Additionally, we emphasize the pressing need for heightened attention directed towards strategies that focus on immune interventions within the female reproductive process, with the ultimate aim of enhancing female fertility.

In vitro maturation (IVM) of human immature oocytes: is it still relevant?

In vitro maturation (IVM) of human immature oocytes has been shown to be a viable option for patients at risk of ovarian hyperstimulation syndrome (OHSS), those seeking urgent fertility preservation and in circumstances where controlled ovarian stimulation is not feasible. Moreover, IVM techniques can be combined with ovarian tissue cryobanking to increase the chances of conception in cancer survivors. The clinical applications of IVM in the field of reproductive medicine are rapidly expanding and the technique is now classified as non-experimental. In contrast to conventional IVF (in vitro fertilization), IVM offers several advantages, such as reduced gonadotropin stimulation, minimal risk of ovarian hyperstimulation syndrome (OHSS), reduced treatment times and lower costs. However, the technical expertise involved in performing IVM and its lower success rates compared to traditional IVF cycles, still pose significant challenges. Despite recent advances, such as innovative biphasic IVM systems, IVM is still an evolving technique and research is ongoing to refine protocols and identify techniques to improve its efficiency and effectiveness. A comprehensive understanding of the distinct mechanisms of oocyte maturation is crucial for obtaining more viable oocytes through in vitro methods, which will in turn lead to significantly improved success rates. In this review, the present state of human IVM programs and future research directions will be discussed, aiming to promote a better understanding of IVM and identify potential strategies to improve the overall efficiency and success rates of IVM programs, which will in turn lead to better clinical outcomes.

Dynamic regulation of semaphorin 7A and adhesion receptors in ovarian follicle remodeling and ovulation

The ovarian follicle is a complex structure that protects and helps in the maturation of the oocyte, and then releases it through the controlled molecular and structural remodeling process of ovulation. The progesterone receptor (PGR) has been shown to be essential in regulating ovulation-related gene expression changes. In this study, we found disrupted expression of the cellular adhesion receptor gene Sema7A in the granulosa cells of PGR-/- mice during ovulation. We subsequently found that expression of Sema7A in preovulatory follicles is promoted by gonadotropins and hypoxia, establishing an asymmetrical pattern with the SEMA7A protein enriched at the apex of large antral follicles. Sema7A expression was downregulated through a PGR-dependent mechanism in the periovulatory period, the abundance of SEMA7A protein was reduced, and the asymmetric pattern became more homogeneous after an ovulatory stimulus. Receptors for Sema7A can either repel or promote intercellular adhesion. During ovulation, striking inverse regulation of repulsive Plxnc1 and adhesive Itga5/Itgb1 receptors likely contributes to dramatic tissue remodeling. The adhesive receptor Itga5 was significantly increased in periovulatory granulosa cells and cumulus-oocyte complexes (COCs), and functional assays showed that periovulatory granulosa cells and COCs acquire increased adhesive phenotypes, while Sema7A repels granulosa cell contact. These findings suggest that the regulation of Sema7A and its associated receptors, along with the modulation of integrin α5, may be critical in establishing the multilaminar ovarian follicle structure and facilitating the remodeling and apical release of the cumulus-oocyte complex during ovulation.

Common mechanisms of physiological and pathological rupture events in biology: novel insights into mammalian ovulation and beyond

Ovulation is a cyclical biological rupture event fundamental to fertilisation and endocrine function. During this process, the somatic support cells that surround the germ cell undergo a remodelling process that culminates in breakdown of the follicle wall and release of a mature egg. Ovulation is driven by known proteolytic and inflammatory pathways as well as structural alterations to the follicle vasculature and the fluid-filled antral cavity. Ovulation is one of several types of systematic remodelling that occur in the human body that can be described as rupture. Although ovulation is a physiological form of rupture, other types of rupture occur in the human body which can be pathological, physiological, or both. In this review, we use intracranial aneurysms and chorioamniotic membrane rupture as examples of rupture events that are pathological or both pathological and physiological, respectively, and compare these to the rupture process central to ovulation. Specifically, we compared existing transcriptomic profiles, immune cell functions, vascular modifications, and biomechanical forces to identify common processes that are conserved between rupture events. In our transcriptomic analysis, we found 12 differentially expressed genes in common among two different ovulation data sets and one intracranial aneurysm data set. We also found three genes that were differentially expressed in common for both ovulation data sets and one chorioamniotic membrane rupture data set. Combining analysis of all three data sets identified two genes (Angptl4 and Pfkfb4) that were upregulated across rupture systems. Some of the identified genes, such as Rgs2, Adam8, and Lox, have been characterised in multiple rupture contexts, including ovulation. Others, such as Glul, Baz1a, and Ddx3x, have not yet been characterised in the context of ovulation and warrant further investigation as potential novel regulators. We also identified overlapping functions of mast cells, macrophages, and T cells in the process of rupture. Each of these rupture systems share local vasoconstriction around the rupture site, smooth muscle contractions away from the site of rupture, and fluid shear forces that initially increase and then decrease to predispose one specific region to rupture. Experimental techniques developed to study these structural and biomechanical changes that underlie rupture, such as patient-derived microfluidic models and spatiotemporal transcriptomic analyses, have not yet been comprehensively translated to the study of ovulation. Review of the existing knowledge, transcriptomic data, and experimental techniques from studies of rupture in other biological systems yields a better understanding of the physiology of ovulation and identifies avenues for novel studies of ovulation with techniques and targets from the study of vascular biology and parturition.

Making a good egg: human oocyte health, aging, and in vitro development

Mammalian eggs (oocytes) are formed during fetal life and establish associations with somatic cells to form primordial follicles that create a store of germ cells (the primordial pool). The size of this pool is influenced by key events during the formation of germ cells and by factors that influence the subsequent activation of follicle growth. These regulatory pathways must ensure that the reserve of oocytes within primordial follicles in humans lasts for up to 50 years, yet only approximately 0.1% will ever be ovulated with the rest undergoing degeneration. This review outlines the mechanisms and regulatory pathways that govern the processes of oocyte and follicle formation and later growth, within the ovarian stroma, through to ovulation with particular reference to human oocytes/follicles. In addition, the effects of aging on female reproductive capacity through changes in oocyte number and quality are emphasized, with both the cellular mechanisms and clinical implications discussed. Finally, the details of current developments in culture systems that support all stages of follicle growth to generate mature oocytes in vitro and emerging prospects for making new oocytes from stem cells are outlined.

Dual trigger improves the pregnancy rate in fresh in vitro fertilization (IVF) cycles compared with the human chorionic gonadotropin (hCG) trigger: a systematic review and meta-analysis of randomized trials

PROPOSE

The purpose of this study was to assess whether the implementation of a "dual trigger" approach, utilizing gonadotropin-releasing hormone agonist (GnRHa) and human chorionic gonadotropin (hCG) in the GnRH antagonist protocol for in vitro fertilization (IVF), leads to improved pregnancy outcomes compared to the conventional hCG trigger alone. Previous meta-analyses have not provided sufficient evidence to support the superiority of the dual trigger over the hCG trigger in fresh or frozen embryo transfer cycles. Thus, a systematic review and meta-analysis of randomized trials were conducted to provide a comprehensive evaluation of the impact of the dual trigger on pregnancy outcomes in fresh or frozen embryo transfer cycles.

METHOD

A systematic review and meta-analysis of randomised controlled trials (RCTs) were conducted. We searched the Medline and Embase databases for articles up to 2023 by using search terms: "dual trigger," "GnRHa," "hCG," "IVF." Eligible RCTs comparing the dual trigger with the hCG trigger were included. The primary outcome was the live birth rate (LBR) per cycle. The secondary outcomes were the number of oocytes retrieved, number of mature oocytes retrieved, implantation rate, biochemical pregnancy rate, CPR, miscarriage rate and ovarian hyperstimulation syndrome (OHSS) rate per started cycle We compared the oocyte maturation and pregnancy outcomes in the dual trigger and hCG trigger groups. In patients undergoing fresh embryo transfer (ET) and frozen-thawed ET, we also conducted a subgroup analysis to evaluate whether dual trigger improves the clinical pregnancy rate (CPR).

RESULTS

We included 10 randomised studies, with 825 participants in the dual trigger group and 813 in the hCG trigger group. Compared with the hCG trigger, dual trigger was associated with a significant increase in the LBR per cycle (odds ratio (OR) = 1.61[1.16, 2.25]), number of oocytes retrieved (mean difference [MD] = 1.05 [0.43, 1.68]), number of mature oocytes retrieved (MD = 0.82 [0. 84, 1.16]), and CPR (OR = 1.48 [1.08, 2.01]). Subgroup analyses revealed that dual trigger was associated with a significantly increased CPR in patients who received fresh ET (OR = 1.68 [1.14, 2.48]). By contrast, the dual trigger was not associated with an increased CPR in the patient group with frozen-thawed ET (OR = 1.15 [0.64, 2.08]).

CONCLUSION

The dual trigger was associated with a significantly higher number of retrieved oocytes, number of mature oocytes, CPR, and LBR in IVF than the hCG trigger. The beneficial effect for fresh ET cycles compared with frozen-thawed ET might be associated with increased endometrial receptivity.

RELEVANCE

After dual trigger, delaying ET due to the concern of endometrial receptivity might not be needed.

A Spatiotemporal Molecular Atlas of the Ovulating Mouse Ovary

Ovulation is essential for reproductive success, yet the underlying cellular and molecular mechanisms are far from clear. Here, we applied high-resolution spatiotemporal transcriptomics to map out cell-type- and ovulation-stage-specific molecular programs as function of time during follicle maturation and ovulation in mice. Our analysis revealed dynamic molecular transitions within granulosa cell types that occur in tight coordination with mesenchymal cell proliferation. We identified new molecular markers for the emerging cumulus cell fate during the preantral-to-antral transition. We describe transcriptional programs that respond rapidly to ovulation stimulation and those associated with follicle rupture, highlighting the prominent roles of apoptotic and metabolic pathways during the final stages of follicle maturation. We further report stage-specific oocyte-cumulus cell interactions and diverging molecular differentiation in follicles approaching ovulation. Collectively, this study provides insights into the cellular and molecular processes that regulate mouse ovarian follicle maturation and ovulation with important implications for advancing therapeutic strategies in reproductive medicine.

Oocyte secreted factors control genes regulating FSH signaling and the maturation cascade in cumulus cells: the oocyte is not in a hurry

PURPOSE

To assess the effects of the oocyte on mRNA abundance of FSHR, AMH and major genes of the maturation cascade (AREG, EREG, ADAM17, EGFR, PTGS2, TNFAIP6, PTX3, and HAS2) in bovine cumulus cells.

METHODS

(1) Intact cumulus-oocyte complexes, (2) microsurgically oocytectomized cumulus-oolema complexes (OOX), and (3) OOX + denuded oocytes (OOX+DO) were subjected to in vitro maturation (IVM) stimulated with FSH for 22 h or with AREG for 4 and 22 h. After IVM, cumulus cells were separated and relative mRNA abundance was measured by RT-qPCR.

RESULTS

After 22 h of FSH-stimulated IVM, oocytectomy increased FSHR mRNA levels (p=0.005) while decreasing those of AMH (p=0.0004). In parallel, oocytectomy increased mRNA abundance of AREG, EREG, ADAM17, PTGS2, TNFAIP6, and PTX3, while decreasing that of HAS2 (p<0.02). All these effects were abrogated in OOX+DO. Oocytectomy also reduced EGFR mRNA levels (p=0.009), which was not reverted in OOX+DO. The stimulatory effect of oocytectomy on AREG mRNA abundance (p=0.01) and its neutralization in OOX+DO was again observed after 4 h of AREG-stimulated IVM. After 22 h of AREG-stimulated IVM, oocytectomy and addition of DOs to OOX caused the same effects on gene expression observed after 22 h of FSH-stimulated IVM, except for ADAM17 (p<0.025).

CONCLUSION

These findings suggest that oocyte-secreted factors inhibit FSH signaling and the expression of major genes of the maturation cascade in cumulus cells. These may be important actions of the oocyte favoring its communication with cumulus cells and preventing premature activation of the maturation cascade.

Beneficial Effects of Catalpol Supplementation during In Vitro Maturation of Porcine Cumulus-Oocyte Complexes

Oxidative stress degrades oocytes during in vitro maturation (IVM). Catalpol, a well-known iridoid glycoside, exhibits antioxidant, anti-inflammatory, and antihyperglycemic effects. In this study, catalpol supplementation was tested on porcine oocyte IVM and its mechanisms. Corticalgranule (GC) distribution, mitochondrial function, antioxidant capacity, DNA damage degree, and real-time quantitative polymerase chain reaction were used to confirm the effects of 10 μmol/L catalpol in the maturation medium during IVM. Catalpol treatment significantly increased the first-pole rate and cytoplasmic maturation in mature oocytes. It also increased oocyte glutathione (GSH), mitochondrial membrane potential and blastocyst cell number. However, DNA damage as well as reactive oxygen species (ROS) and malondialdehyde (MDA) levels. Mitochondrial membrane potential and blastocyst cell number were also increased. Thus, the supplementation of 10 μmol/L catalpol in the IVM medium improves porcine oocyte maturation and embryonic development.

The protective effect of resveratrol on largemouth bass (Micropterus salmoides) during out-of-season spawning

In aquaculture production, out-of-season spawning is beneficial to solve the seasonal shortage of fry that are normally produced once annually by species such as largemouth bass (Micropterus salmoides), thereby implementing year-round fry production. Maintaining low temperature over a period of several months can delay largemouth bass ovarian development, but it can cause severe stress to their reproductive function, leading to decreased fertility during out-of-season spawning. Feeding with antioxidants is one of the most effective methods to alleviate the negative effects of low temperature stress. Therefore, the purpose of this study is to: (a) evaluate the changes in oocyte morphology, antioxidant capacity, reproductive hormone-related index, cell apoptosis and autophagy during the out-of-season spawning of largemouth bass, and (b) to investigate the protective effect of the antioxidant resveratrol on this fish during out-of-season spawning from May through August. The study was divided into two groups (three replicates per group, 2000 fish per replicate): control group (Control) (exposure to water temperature of 12-17 °C) and resveratrol supplementation group (Res) (exposure to water temperature of 12-17 °C and fed with 200 mg/kg resveratrol). The results show that: (1) The serum hormones LH and E2 increased first and then remained unchanged, and the ovarian section showed that the ovary remained in stage IV. (2) In the process of off-season reproduction, a large number of follicles experienced follicular atresia, accompanied by endoplasmic reticulum expansion, nuclear chromatin condensation and mitochondrial swelling, which was relieved after feeding resveratrol. (3) Resveratrol decreased the ovarian ROS content and improved the activities of CAT and other antioxidant enzymes in the ovary and liver to some extent. (4) Resveratrol reduced the level of pro-apoptotic (Bax, Caspase3, Caspase8, Caspase9) and autophagy-related components (LC3-B, Beclin-1) while increasing the transcription level of anti-apoptotic (Bcl-2) factors. These findings suggest that resveratrol alleviates some adverse effects of largemouth bass during out-of-season spawning to some extent and provide a model for efficient and high-quality out-of-season spawning.

Beneficial effects of fibroblast growth factor 10 supplementation during in vitro maturation of buffalo cumulus-oocyte complexes

Fibroblast growth factor 10 (FGF10) is an important regulator of the mammalian cumulus-oocyte complex that plays a crucial role in oocyte maturation. In this study, we investigated the effects of FGF10 supplementation on the in vitro maturation (IVM) of buffalo oocytes and its related mechanisms. During IVM, the maturation medium was supplemented with a range of concentrations of FGF10 (0, 0.5, 5, and 50 ng/mL) and the resulting effects were corroborated using aceto-orcein staining, TUNEL apoptosis assay, detection of Cdc2/Cdk1 kinase in oocytes, and real-time quantitative PCR. In matured oocytes, the 5 ng/mL-FGF10 treatment resulted in a significantly increased nuclear maturation rate, which increased the activity of maturation-promoting factor (MPF) and enhanced buffalo oocyte maturation. Furthermore, it treatment significantly inhibited the apoptosis of cumulus cells, while simultaneously promoting its proliferation and expansion. This treatment also increased the absorption of glucose in cumulus cells. Thus, our results indicate that adding an appropriate concentration of FGF10 to a maturation medium during IVM can be beneficial to the maturation of buffalo oocytes and improve the potential of embryo development.

ABCC4 is a PGE2 efflux transporter in the ovarian follicle: A mediator of ovulation and a potential non-hormonal contraceptive target

The role of prostaglandins (PGs) in the ovulatory process is known. However, the role of the ATP binding cassette subfamily C member 4 (ABCC4), transmembrane PG carrier protein, in ovulation remains unknown. We report herein that ABCC4 expression is significantly upregulated in preovulatory human granulosa cells (GCs). We found that PGE2 efflux in cultured human GCs is mediated by ABCC4 thus regulating its extracellular concentration. The ABCC4 inhibitor probenecid demonstrated effective blocking of ovulation and affects key ovulatory genes in female mice in vivo. We postulate that the reduction in PGE2 efflux caused by the inhibition of ABCC4 activity in GCs decreases the extracellular concentration of PGE2 and its ovulatory effect. Treatment of female mice with low dose of probenecid as well as with the PTGS inhibitor indomethacin or Meloxicam synergistically blocks ovulation. These results support the hypothesis that ABCC4 has an important role in ovulation and might be a potential target for non-hormonal contraception, especially in combination with PGE2 synthesis inhibitors. These findings may fill the gap in understanding the role of ABCC4 in PGE2 signaling, enhance the understanding of ovulatory disorders, and facilitate the treatment and control of fertility.

Resolving the challenge of insoluble production of mature human growth differentiation factor 9 protein (GDF9) in E. coli using bicistronic expression with thioredoxin

Growth differentiation factor 9 (GDF9) is an oocyte-derived protein with fundamental functions in folliculogenesis. While the crucial contributions of GDF9 in follicular survival have been revealed, crystallographic studies of GDF9 structure have not yet been carried out, essentially due to the insoluble expression of GDF9 in E. coli and lack of appropriate source for structural studies. Therefore, in this study, we investigated the impact of different expression rate of bacterial thioredoxin (TrxA) using bicistronic expression constructs to induce the soluble expression of mature human GDF9 (hGDF9) driven by T7 promoter in E. coli. Our findings revealed that in BL21(DE3), the high rate of TrxA co-expression at 30 °C was sufficiently potent for the soluble expression of hGDF9 and reduction of inclusion body formation by 4 fold. We also successfully confirmed the bioactivity of the purified soluble hGDF9 protein by evaluation of follicle-stimulating hormone receptor gene expression in bovine cumulus cells derived from small follicles. This study is the first to present an effective approach for expression of bioactive form of hGDF9 using TrxA co-expression in E. coli, which may unravel the current issues regarding structural analysis of hGDF9 protein and consequently provide a better insight into hGDF9 functions and interactions.

Soft ovarian stimulation protocol in polycystic ovary syndromes women inspired by gonadotropin stimulated intrauterine insemination cycles converted to rescue IVF: time to shift the focus “retrospective study”

Background

Polycystic ovary syndrome (PCOs) women usually exhibit a high luteinizing hormone (LH) and hypersensitivity to exogenous gonadotropins stimulation which is a tremendous risk to ovarian hyperstimulation syndrome (OHSS). Since the pathophysiology of PCOS is mysterious, an aetiological approach to the treatment is difficult and should be individually designed. These features affect the outcome of treatment including ovulation and success rate. Also, PCOS women who have difficulty conceiving, frequently experience substantial treatment burden, risk, and psychological distress. Recently, a renewed interest has emerged in patient-friendly, low-risk, and less costly IVF treatments. Our study proposed a new soft protocol in PCOS ovrian stimulation without prior pituitary desensitization followed by fresh embryo transfer. Patients and methods: a retrospective cohort study was conducted between January 2018 to December 2021, including 48 out of 325 women with PCOS who underwent gonadotropin-stimulated intrauterine insemination cycles but due to unexpectedly high response with risk of multiple pregnancies and OHSS, they had been shifted to a rescue IVF and fresh embryo transfer. The primary outcomes were biochemical pregnancy, implantation rate, clinical pregnancy, rate of miscarriage, OHSS, and multiple pregnancies. Secondary outcomes were the endocrinological profiles, gonadotropin dose, and duration of stimulation. This study aims to evaluate the outcomes in the conversion of high-response gonadotropin intrauterine insemination (IUI) cycles to “rescue” in vitro fertilization (IVF/fresh embryo transfer) regarding implantation rates, pregnancy rates, and ovarian hyperstimulation syndrome (OHSS).

Results

This study used a low dose gonadotropin injections (2.1 ± 1.4) for an average duration of (9.1 ± 1.2) and showed a high success pregnancy rate: biochemical pregnancies (56.2%), implantation rate (50.2%), clinical pregnancy rate (49.9%), and miscarriage rate (8.5%). Multiple pregnancies occurred in (6.6%) and OHSS(4.4%) only in a mild form.

Conclusion

Our study revealed that ovarian stimulation without prior pituitary suppression in high responders was feasible to improve the implantation rate and alleviate profound OHSS without compromising the pregnancy outcomes. This encourages all fertility specialists to implement this new protocol with expected high responders as an alternative to the conventional cycle segmentation protocol: GnRH agonist-antagonist IVF/freeze-all strategy.

Pentraxin 3 regulates tyrosine kinase inhibitor-associated cardiomyocyte contraction and mitochondrial dysfunction via ERK/JNK signalling pathways

BACKGROUND

Hepatocellular carcinoma (HCC) patients suffer varying degrees of heart dysfunction after tyrosine kinase inhibitor (TKI) treatment. Interestingly, HCC patients often have higher levels of pentraxin 3 (PTX3), and PTX3 inhibition was found to improve left ventricular dysfunction in animal models.

OBJECTIVES

We sought to assess the therapeutic potential of PTX3 inhibition on TKI-associated cardiotoxicity.

METHODS

We used a human embryonic stem cell line, RUES2, to generate cardiomyocyte cultures (RUES2-CM) for functional testing. We also assessed heart function and PTX3 expression levels in 16 HCC patients who received TKI treatment, 3 HCC patients who did not receive TKIs, and 7 healthy volunteers.

RESULTS

Significantly higher PTX3 expression was noted in HCC patients with TKI treatment versus those without, and 38% of male and 33% of female patients had QTc prolongation after TKI treatment. Treatment of cardiomyocyte cultures with sorafenib also increased PTX3 expression and induced cytoskeletal remodelling, contraction reduction, sodium current inhibition, and mitochondrial respiratory dysfunction. PTX3 colocalised with CD44 in cardiomyocytes, and cardiomyocyte contraction, mitochondrial respiratory function, and regular cytoskeletal and apoptotic protein expression were restored with PTX3 inhibition. CD44 knockdown confirmed PTX3/CD44 signalling. These results suggest a possible mechanism in which sorafenib treatment increases PTX3 expression, thereby resulting in reduced extracellular signal-regulated kinase (ERK) 1/2 expression that affects cardiomyocyte contraction, while also activating c-Jun N-terminal kinase (JNK) downstream pathways to disrupt mitochondrial respiration and trigger apoptosis.

CONCLUSIONS

TKI-induced cardiotoxicity may be partly mediated by the upregulation of PTX3, and thus PTX3 inhibition has potential as a therapeutic strategy.

Granulosa Cell Specific Loss of Adar in Mice Delays Ovulation, Oocyte Maturation and Leads to Infertility

Adenosine deaminases acting on RNA-(ADAR) comprise one family of RNA editing enzymes that specifically catalyze adenosine to inosine (A-to-I) editing. A granulosa cell (GC) specific Adar depleted mouse model [Adar flox/flox:Cyp19a1-Cre/+ (gcAdarKO)] was used to evaluate the role of ADAR1 during the periovulatory period. Loss of Adar in GCs led to failure to ovulate at 16 h post-hCG, delayed oocyte germinal vesicle breakdown and severe infertility. RNAseq analysis of GC collected from gcAdarKO and littermate control mice at 0 and 4 h post-hCG following a super-ovulatory dose of eCG (48 h), revealed minimal differences after eCG treatment alone (0 h), consistent with normal folliculogenesis observed histologically and uterine estrogenic responses. In contrast, 300 differential expressed genes (DEGs; >1.5-fold change and FDRP < 0.1) were altered at 4 h post-hCG. Ingenuity pathway analysis identified many downstream targets of estrogen and progesterone pathways, while multiple genes involved in inflammatory responses were upregulated in the gcAdarKO GCs. Temporal expression analysis of GCs at 0, 4, 8, and 12 h post-hCG of Ifi44, Ifit1, Ifit3b, and Oas1g and Ovgp1 confirmed upregulation of these inflammatory and interferon genes and downregulation of Ovgp1 a glycoprotein involved in oocyte zona pellucida stability. Thus, loss of ADAR1 in GCs leads to increased expression of inflammatory and interferon response genes which are temporally linked to ovulation failure, alterations in oocyte developmental progression and infertility.

Sustained Activation of CLR/RAMP Receptors by Gel-Forming Agonists

Background: Adrenomedullin (ADM), adrenomedullin 2 (ADM2), and CGRP family peptides are important regulators of vascular vasotone and integrity, neurotransmission, and fetoplacental development. These peptides signal through CLR/RAMP1, 2, and 3 receptors, and protect against endothelial dysfunction in disease models. As such, CLR/RAMP receptor agonists are considered important therapeutic candidates for various diseases. Methods and Results: Based on the screening of a series of palmitoylated chimeric ADM/ADM2 analogs, we demonstrated a combination of lipidation and accommodating motifs at the hinge region of select peptides is important for gaining an enhanced receptor-activation activity and improved stimulatory effects on the proliferation and survival of human lymphatic endothelial cells when compared to wild-type peptides. In addition, by serendipity, we found that select palmitoylated analogs self-assemble to form liquid gels, and subcutaneous administration of an analog gel led to the sustained presence of the peptide in the circulation for >2 days. Consistently, subcutaneous injection of the analog gel significantly reduced the blood pressure in SHR rats and increased vasodilation in the hindlimbs of adult rats for days. Conclusions: Together, these data suggest gel-forming adrenomedullin analogs may represent promising candidates for the treatment of various life-threatening endothelial dysfunction-associated diseases such as treatment-resistant hypertension and preeclampsia, which are in urgent need of an effective drug.

RNA binding protein IGF2BP1 meditates oxidative stress-induced granulosa cell dysfunction by regulating MDM2 mRNA stability in an m6A-dependent manner

Both genetic and microenvironmental detrimental factors are involved in ovarian dysfunction, leading to the increasing rate of involuntary childlessness in recent years. Oxidative stress (OS), which is characterized by the imbalance of redox system with redundant reactive oxygen species (ROS) overwhelming the antioxidant defense, is regarded as one of the culprits of ovarian dysfunction. OS causes damage to various types of ovarian cells including granulosa cells (GCs), jeopardizing the ovarian microenvironment, disturbing follicular development and participating in various female reproductive disorders. However, the specific molecular pathological mechanisms underlying this process have not been fully elucidated. In this study, we found that 3-nitropropionic acid (3-NP) treatment led to significant IGF2BP1 downregulation via, at least partially, inducing ROS overproduction. IGF2BP1 regulates GCs viability, proliferation, cell cycle and cellular senescence by enhancing MDM2 mRNA stability in an m6A-dependant manner. IGF2BP1 overexpression partially rescued 3-NP induced GCs damages, while ectopically expressed MDM2 alleviated both 3-NP or IGF2BP1-knockdown induced GCs dysfunction. These results reveal an epigenetic molecular mechanism underlying OS-related GCs disorders, which may help to establish a novel potential clinical marker for predicting the GCs status as well as the follicular developmental potential.

Single-cell RNA-seq analysis and cell-cluster deconvolution of the human preovulatory follicular fluid cells provide insights into the pathophysiology of ovarian hyporesponse

Reduction in responsiveness to gonadotropins or hyporesponsiveness may lead to the failure of in vitro fertilization (IVF), due to a low number of retrieved oocytes. The ovarian sensitivity index (OSI) is used to reflect the ovarian responsiveness to gonadotropin stimulation before IVF. Although introduced to clinical practice already years ago, its usefulness to predict clinical outcomes requires further research. Nevertheless, pathophysiological mechanisms of ovarian hyporesponse, along with advanced maternal age and in younger women, have not been fully elucidated. Follicles consist of multiple cell types responsible for a repertoire of biological processes including responding to pituitary gonadotropins necessary for follicle growth and oocyte maturation as well as ovulation. Encouraging evidence suggests that hyporesponse could be influenced by many contributing factors, therefore, investigating the variability of ovarian follicular cell types and their gene expression in hyporesponders is highly informative for increasing their prognosis for IVF live birth. Due to advancements in single-cell analysis technologies, the role of somatic cell populations in the development of infertility of ovarian etiology can be clarified. Here, somatic cells were collected from the fluid of preovulatory ovarian follicles of patients undergoing IVF, and RNA-seq was performed to study the associations between OSI and gene expression. We identified 12 molecular pathways differentially regulated between hypo- and normoresponder patient groups (FDR<0.05) from which extracellular matrix organization, post-translational protein phosphorylation, and regulation of Insulin-like Growth Factor (IGF) transport and uptake by IGF Binding Proteins were regulated age-independently. We then generated single-cell RNA-seq data from matching follicles revealing 14 distinct cell clusters. Using cell cluster-specific deconvolution from the bulk RNA-seq data of 18 IVF patients we integrated the datasets as a novel approach and discovered that the abundance of three cell clusters significantly varied between hypo- and normoresponder groups suggesting their role in contributing to the deviations from normal ovarian response to gonadotropin stimulation. Our work uncovers new information regarding the differences in the follicular gene expression between hypo- and normoresponders. In addition, the current study fills the gap in understanding the inter-patient variability of cell types in human preovulatory follicles, as revealed by single-cell analysis of follicular fluid cells.

Simultaneous free fatty acid elevations and accelerated desaturation in plasma and oocytes in early postpartum dairy cows under intensive feeding management

A severe negative energy balance and high circulating free fatty acids (FFA) in postpartum cows impair fertility. The lipotoxicity of FFA has been shown to decrease the quality of bovine oocytes in vitro. Therefore, excess FFA in cells is converted to triacylglycerol (TAG), a non-toxic form, to avoid lipotoxicity. We recently reported that the TAG content in oocytes was higher in postpartum lactating cows subjected to grazing management than in heifers (Theriogenology 176: 174-182, 2021). The present study investigated the compositions of the energy metabolism-related lipids, FFA and TAG, in the plasma and oocytes of cows at different lactation stages under indoor intensive feeding management in order to obtain insights into lipotoxicity in oocytes, particularly those in early postpartum cows. Blood and oocytes were collected from 20 lactating cows categorized into the following lactation groups: 20-30 days in milk (DIM) (n = 5), 40-50 DIM (n = 5), 60-80 DIM (n = 5), and 130-160 DIM (n = 5). Daily energy balance data were obtained for 3 weeks prior to oocyte collection using the ovum pick up (OPU) method. The contents and compositions of FFA and TAG in plasma and oocytes were analyzed using liquid chromatography-mass spectrometry. As expected, plasma FFA was high at 20-30 DIM, decreased by 50 DIM, and was maintained at a low level for the remainder of the experimental period. Similar changes were observed in oocyte FFA and TAG with DIM as plasma FFA. Oocyte FFA positively correlated with plasma FFA (P < 0.05), but negatively correlated with the mean energy balance 1 and 21 days before OPU (P < 0.05). Relationships were noted between the composition and content of FFA in plasma and oocytes, with the FFA 16:1/16:0 and 18:1/18:0 ratios positively correlating with the total amount of FFA (P < 0.05). Elevated oocyte FFA in cows in the early postpartum period under intensive feeding management suggested that oocytes were at a high risk of FFA lipotoxicity. Furthermore, the present results implied that the severe negative energy balance in the previous few weeks was closely related to increases in oocyte FFA, which supports the importance of long-term cow feeding management for preserving the quality of oocytes in the early postpartum period. The present results provide insights into the effects of high circulating FFA on the fertility of postpartum cows.

Long-term role of neonatal microglia and monocytes in ovarian health

Early life microglia are essential for brain development, and developmental disruption in microglial activity may have long-term implications for the neuroendocrine control of reproduction. We and others have previously shown that early life immune activation compromises the long-term potential for reproductive function in females. However, the supportive role of microglia in female reproductive development is still unknown. Here, we examined the long-term programming effects of transient neonatal microglial and monocyte ablation on hypothalamic-pituitary-gonadal (HPG) axis function in female rats. We employed a Cx3cr1-Dtr transgenic Wistar rat model to acutely ablate microglia and monocytes, commencing on either postnatal day (P) 7 or 14, since the development of the HPG axis in female rodents primarily occurs during the first two to three postnatal weeks. After an acutely diminished expression of microglia and monocyte genes in the brain and ovaries, respectively, microglia had repopulated the brain by P21, albeit that cellular complexity was still reduced in both groups at this time. Removal of microglia and monocytes on P7, but not P14 reduced circulating luteinising hormone levels in adulthood and ovarian gonadotropin receptors mRNA. These changes were notably associated with fewer primary and antral follicles in these rats. These data suggest that transient ablation of microglia and monocytes at the start of the second but not the third postnatal week has long-term effects on ovarian health. The findings highlight the important developmental role of a healthy immune system for female potential reproductive capacity and the importance of critical developmental periods to adult ovarian health.

Diverse actions of sirtuin-1 on ovulatory genes and cell death pathways in human granulosa cells

BACKGROUND

Human granulosa-lutein cells (hGLCs) amply express sirtuin-1 (SIRT1), a NAD + -dependent deacetylase that is associated with various cellular functions. SIRT1 was shown to elevate cAMP on its own and additively with human chorionic gonadotropin (hCG), it is therefore interesting to examine if SIRT1 affects other essential hGLC functions.

METHODS

Primary hGLCs, obtained from the follicular aspirates of women undergoing IVF and SV40-transfected, immortalized hGLCs (SVOG cells), were used. Primary cells were treated with SIRT1 specific activator SRT2104, as well as hCG or their combination. Additionally, siRNA-targeting SIRT1 construct was used to silence endogenous SIRT1 in SVOG cells. PTGS2, EREG, VEGFA and FGF2 expression was determined using quantitative polymerase chain reaction (qPCR). Apoptotic and necroptotic proteins were determined by specific antibodies in western blotting. Cell viability/apoptosis was determined by the XTT and flow cytometry analyses. Data were analyzed using student t-test or Mann-Whitney U test or one-way ANOVA followed by Tukey HSD post hoc test.

RESULTS

In primary and immortalized hGLCs, SRT2104 significantly upregulated key ovulatory and angiogenic genes: PTGS2, EREG, FGF2 and VEGFA, these effects tended to be further augmented in the presence of hCG. Additionally, SRT2104 dose and time-dependently decreased viable cell numbers. Flow cytometry of Annexin V stained cells confirmed that SIRT1 reduced live cell numbers and increased late apoptotic and necrotic cells. Moreover, we found that SIRT1 markedly reduced anti-apoptotic BCL-XL and MCL1 protein levels and increased cleaved forms of pro-apoptotic proteins caspase-3 and PARP. SIRT1 also significantly induced necroptotic proteins RIPK1 and MLKL. RIPK1 inhibitor, necrostatin-1 mitigated SIRT1 actions on RIPK1 and MLKL but also on cleaved caspase-3 and PARP and in accordance on live and apoptotic cells, implying a role for RIPK1 in SIRT1-induced cell death. SIRT1 silencing produced inverse effects on sorted cell populations, anti-apoptotic, pro-apoptotic and necroptotic proteins, corroborating SIRT1 activation.

CONCLUSIONS

These findings reveal that in hGLCs, SIRT1 enhances the expression of ovulatory and angiogenic genes while eventually advancing cell death pathways. Interestingly, these seemingly contradictory events may have occurred in a cAMP-dependent manner.

Heat-induced increases in body temperature in lactating dairy cows: impact on the cumulus and granulosa cell transcriptome of the periovulatory follicle

Cows acutely heat stressed after a pharmacologically induced luteinizing hormone (LH) surge had periovulatory changes in the follicular fluid proteome that may potentiate ovulation and impact oocyte developmental competence. Because the cellular origins of differentially abundant proteins were not known, we have examined the cumulus and granulosa cell transcriptomes from the periovulatory follicle in cows exhibiting varying levels of hyperthermia when occurring after the LH surge. After pharmacological induction of a dominant follicle, lactating dairy cows were administered gonadotropin releasing hormone (GnRH) and maintained in thermoneutral conditions (~67 temperature-humidity index [THI]) or heat stress conditions where THI was steadily increased for ~12 h (71 to 86 THI) and was sufficient to steadily elevate rectal temperatures. Cumulus-oocyte complexes and mural granulosa cells were recovered by transvaginal aspiration of dominant follicle content ~16 h after GnRH. Rectal temperature was used as a continuous, independent variable to identify differentially expressed genes (DEGs) increased or decreased per each 1 °C change in temperature. Cumulus (n = 9 samples) and granulosa (n = 8 samples) cells differentially expressed (false discovery rate [FDR] < 0.05) 25 and 87 genes, respectively. The majority of DEGs were upregulated by hyperthermia. Steady increases in THI are more like the "turning of a dial" than the "flipping of a switch." The moderate but impactful increases in rectal temperature induced modest fold changes in gene expression (<2-fold per 1 °C change in rectal temperature). Identification of cumulus DEGs involved in cell junctions, plasma membrane rafts, and cell-cycle regulation are consistent with marked changes in the interconnectedness and function of cumulus after the LH surge. Depending on the extent to which impacts may be occurring at the junctional level, cumulus changes may have indirect but impactful consequences on the oocyte as it undergoes meiotic maturation. Two granulosa cell DEGs have been reported by others to promote ovulation. Based on what is known, several other DEGs are suggestive of impacts on collagen formation or angiogenesis. Collectively these and other findings provide important insight regarding the extent to which the transcriptomes of the components of the periovulatory follicle (cumulus and mural granulosa cells) are affected by varying degrees of hyperthermia.

The extent of the abundance of exosomal and non-exosomal extracellular miRNAs in the bovine follicular fluid

Follicular fluid (FF) plays an important role during follicular development and it contains several bioactive molecules including extracellular microRNAs (ECmiRNAs) that may mediate cell-cell communication during follicular development. Yet, the distribution patterns of ECmiRNAs in FF is not well characterized. This study aims to investigate the distribution of ECmiRNAs in two major fractions, namely exosomal and non-exosomal, of bovine follicular fluid (bFF). Exosomal and non-exosomal fractions from bFF were separated using Exoquick™ exosomes precipitation kit. miRNA expression was evaluated using the human miRCURY LNA™ Universal RT miRNA PCR array system. Transmission electron microscopy and immunoblotting revealed that the isolated vesicles were exosomes. The real-time PCR-based expression analysis revealed that 516 miRNAs were detected in the exosomal fraction of bFF, while 393 miRNAs were detected in the non-exosomal fraction. Among the detected miRNAs, a total of 370 miRNAs were detected in both fractions, while 145 miRNAs and 23 miRNAs were solely detected in exosomal and non-exosomal fractions, respectively. Exploratory pathway analysis showed that the genes targeted by exosomal and non-exosomal miRNAs to be involved in MAPK, Wnt, FoxO, TGF-beta, Oxytocin, ErbB, PI3K-Akt, Neurotrophin signalling pathways which are believed to be involved in follicular development, cell proliferation, and meiotic resumption. The results of our study demonstrated that besides the exosomal fraction, non-exosomal fractions can carry a significant amount of miRNAs in bFF where the exosomal fraction carries a significantly higher number of detectable miRNAs.

An Investigation of the Effects of Chronic Zonisamide, Sultiam, Lacosamide, Clobazam, and Rufinamide Antiseizure Drugs on Foliculogenesis in Ovarian Tissue in Prepubertal Non-Epileptic Rats

We aimed to determine the morphological and histological effects of zonisamide, sultiam, lacosamide, clobazam, and rufinamide on ovarian folliculogenesis in rats. Sixty female Wistar rats were equally divided into 6 experimental groups, including control group, zonisamide, sultiam, lacosamide, clobazam, and rufinamide were administered by gavage for 90 days. According to the daily vaginal smears of the rats in the proestrus and diester phases of the estrus cycle, their ovaries were removed and placed in the fixation solution. Immunohistochemical and apoptosis staining protocols were applied. The number of healthy follicles in the control group was found to be statistically significantly higher when compared to the antiseizure drug groups (p<0.001). The number of corpus luteum was found to be statistically significantly lower in the control group when compared with the anti-seizure drug groups (p<0.001). There was a significant difference in the number of TUNEL positive apoptotic follicles between the control and drug groups (p<0.001). There was a significant difference in the number of TUNEL positive apoptotic follicles between the control and drug groups (p<0.001). HSCORE, immunohistochemical EGF, IGF-1 and GDF-9 staining, a very strong immunoreaction was observed in the ovarian multilaminar primary follicle granulosa cells and oocytes in the control group (p<0.001), and an immunoreaction ranging from weak to medium was observed in the antiseizure drug groups. Long-term anti-seizure drug therapy with zonisamide, sultiam, lacosamide, clobazam, and rufinamide from prepubertal to adulthood causes apoptosis and disruption of folliculogenesis in the ovarian follicles of nonepileptic rats.

PUMILIO-mediated translational control of somatic cell cycle program promotes folliculogenesis and contributes to ovarian cancer progression

Translational control is a fundamental mechanism regulating animal germ cell development. Gonadal somatic cells provide support and microenvironment for germ cell development to ensure fertility, yet the roles of translational control in gonadal somatic compartment remain largely undefined. We found that mouse homolog of conserved fly germline stem cell factor Pumilio, PUM1, is absent in oocytes of all growing follicles after the primordial follicle stage, instead, it is highly expressed in somatic compartments of ovaries. Global loss of Pum1, not oocyte-specific loss of Pum1, led to a significant reduction in follicular number and size as well as fertility. Whole-genome identification of PUM1 targets in ovarian somatic cells revealed an enrichment of cell proliferation pathway, including 48 key regulators of cell phase transition. Consistently granulosa cells proliferation is reduced and the protein expression of the PUM-bound Cell Cycle Regulators (PCCR) were altered accordingly in mutant ovaries, and specifically in granulosa cells. Increase in negative regulator expression and decrease in positive regulators in the mutant ovaries support a coordinated translational control of somatic cell cycle program via PUM proteins. Furthermore, postnatal knockdown, but not postnatal oocyte-specific loss, of Pum1 in Pum2 knockout mice reduced follicular growth and led to similar expression alteration of PCCR genes, supporting a critical role of PUM-mediated translational control in ovarian somatic cells for mammalian female fertility. Finally, expression of human PUM protein and its regulated cell cycle targets exhibited significant correlation with ovarian cancer and prognosis for cancer survival. Hence, PUMILIO-mediated cell cycle regulation represents an important mechanism in mammalian female reproduction and human cancer biology.

Nanoparticles Accumulate in the Female Reproductive System during Ovulation Affecting Cancer Treatment and Fertility

Throughout the female menstrual cycle, physiological changes occur that affect the biodistribution of nanoparticles within the reproductive system. We demonstrate a 2-fold increase in nanoparticle accumulation in murine ovaries and uterus during ovulation, compared to the nonovulatory stage, following intravenous administration. This biodistribution pattern had positive or negative effects when drug-loaded nanoparticles, sized 100 nm or smaller, were used to treat different cancers. For example, treating ovarian cancer with nanomedicines during mouse ovulation resulted in higher drug accumulation in the ovaries, improving therapeutic efficacy. Conversely, treating breast cancer during ovulation, led to reduced therapeutic efficacy, due to enhanced nanoparticle accumulation in the reproductive system rather than at the tumor site. Moreover, chemotherapeutic nanoparticles administered during ovulation increased ovarian toxicity and decreased fertility compared to the free drug. The menstrual cycle should be accounted for when designing and implementing nanomedicines for females.

Activin a promotes hyaluronan production and upregulates versican expression in human granulosa cells via the ALK4-SMAD2/3-SMAD4 signaling pathway

Hyaluronan is a structural component of the expanded cumulus matrix, and hyaluronan synthase 2 (HAS2) is the major enzyme for the synthesis of hyaluronan in humans. Versican cross-links the hyaluronan-rich matrix to cumulus cells and is critical for successful ovulation. Activin A is a critical intrafollicular regulator of ovarian function. Although activin A has been shown to promote cumulus matrix expansion in mice, the functional role of activin A in the regulation of cumulus expansion in the human ovary remains to be elucidated. Using primary and immortalized human granulosa-lutein (hGL) cells as study models, we provide the first data showing that activin A increased the production of hyaluronan by upregulating the expression of HAS2 in these cells. Additionally, activin A also promoted the expression of the hyaluronan-binding protein versican. Moreover, using inhibitor- and siRNA-mediated inhibition approaches, we found that these stimulatory effects of activin A are most likely mediated through the type I receptor ALK4-mediated SMAD2/SMAD3-SMAD4 signaling pathway. Notably, the ChIP analyses demonstrated that SMAD4 could bind to human HAS2 and VERSICAN promoters. The results obtained from this in vitro study suggest that locally produced activin A plays a functional role in the regulation of hyaluronan production and stabilization in hGL cells.

Connective tissue growth factor mediates bone morphogenetic protein 2-induced increase in hyaluronan production in luteinized human granulosa cells

BACKGROUND

Hyaluronan is the main component of the cumulus-oocyte complex (COC) matrix, and it maintains the basic structure of the COC during ovulation. As a member of the transforming growth factor β (TGF-β) superfamily, bone morphogenetic protein 2 (BMP2) has been identified as a critical regulator of mammalian folliculogenesis and ovulation. However, whether BMP2 can regulate the production of hyaluronan in human granulosa cells has never been elucidated.

METHODS

In the present study, we investigated the effect of BMP2 on the production of hyaluronan and the underlying molecular mechanism using both immortalized (SVOG) and primary human granulosa-lutein (hGL) cells. The expression of three hyaluronan synthases (including HAS1, HAS2 and HAS3) were examined following cell incubation with BMP2 at different concentrations. The concentrations of the hyaluronan cell culture medium were determined by enzyme-linked immunosorbent assay (ELISA). The TGF-β type I receptor inhibitors (dorsomorphin and DMH-1) and small interfering RNAs targeting ALK2, ALK3, ALK6 and SMAD4 were used to investigate the involvement of TGF-β type I receptor and SMAD-dependent pathway.

RESULTS

Our results showed that BMP2 treatment significantly increased the production of hyaluronan by upregulating the expression of hyaluronan synthase 2 (HAS2). In addition, BMP2 upregulates the expression of connective tissue growth factor (CTGF), which subsequently mediates the BMP2-induced increases in HAS2 expression and hyaluronan production because overexpression of CTGF enhances, whereas knockdown of CTGF reverses, these effects. Notably, using kinase inhibitor- and siRNA-mediated knockdown approaches, we demonstrated that the inductive effect of BMP2 on the upregulation of CTGF is mediated by the ALK2/ALK3-mediated SMAD-dependent signaling pathway.

CONCLUSIONS

Our findings provide new insight into the molecular mechanism by which BMP2 promotes the production of hyaluronan in human granulosa cells.