Ovarian Follicle Development Research Articles

Baicalin improves the functions of granulosa cells and the ovary in aged mice through the mTOR signaling pathway

BackgroundThe mammalian follicle is the basic functional unit of the ovary, and its normal development is required to obtaining oocytes capable of fertilization. As women get older or decline in ovarian function due to certain pathological factors, the growth and development of follicles becomes abnormal, which ultimately leads to infertility and other related female diseases. Kuntai capsules are currently used in clinical practice to improve ovarian function, and they contain the natural compound Baicalin, which is a natural compound with important biological activities. At present, the role and mechanism of Baicalin in the development of ovarian follicles is unclear.MethodsHuman primary granulosa cells collected from follicular fluid, and then cultured and treated with Baicalin or its normal control, assessed for viability, subjected to RT-PCR, western blotting, flow cytometry, and hormone analyses. The estrus cycle and oocytes of CD-1 mice were studied after Baicalin administration and compared with controls. Ovaries were collected from the mice and subjected to hematoxylin-eosin staining and immunohistochemistry analysis.ResultsWe showed that Baicalin had a dose-dependent effect on granulosa cells cultured in vitro. A low concentration of Baicalin (for example, 10 μM) helped to maintain the viability of granulosa cells; however, at a concentration exceeding 50 μM, it exerted a toxic effect. A low concentration significantly improved the viability of granulosa cells and inhibited cell apoptosis, which may be related to the resultant upregulation of Bcl-2 expression and downregulation of Bax and Caspase 3. By constructing a hydrogen peroxide-induced cell oxidative stress damage model, we found that Baicalin reversed the cell damage caused by hydrogen peroxide. In addition, Baicalin increased the secretion of estradiol and progesterone by upregulating P450arom and stAR. The results of the in vivo experiment showed that the intragastric administration of Baicalin to aged mice improved the estrous cycle and oocyte quality. Furthermore, we observed that Baicalin enhanced the viability of granulosa cells through the mTOR pathway, which in turn improve ovarian function.ConclusionThese results indicate that Baicalin could improve the viability of ovarian granulosa cells and the secretion of steroid hormones and thus could help to improve degenerating ovarian function and delay ovarian aging.

Polymorphism in the 5ʹ regulatory region of CTNNB1 gene and association with age at first lay and egg production

ABSTRACT 1. The Wnt signalling pathway is centred on the fact that catenin beta-1(CTNNB1) participates in the regulation of ovarian follicle development. The aim of the following study was to identify polymorphisms in the 5ʹ regulatory region of the chicken CTNNB1 gene and evaluate the association between SNPs and egg production traits. 2. The study demonstrated that the 5ʹ regulatory region of the CTNNB1 gene has 10 SNPs in the investigated Jining Bairi chickens. After Bonferroni correction for multiple testing, five SNPs (rs315692306, 2:g43385123, rs735854102, 2:g43385457 and rs737907370) were significantly correlated with egg laying traits. 3. An association study of the haplotypes with egg laying traits revealed that both haplotypes in block 1 (consisting of rs735052881, rs740662190, rs315692306, and 2:43385123) and block 2 (consisting of rs735854102 and 2:g43385457) were associated with point of lay age and the number of eggs laid at 18–23 weeks. Prediction of transcription factor-binding sites showed that transcription factors changed after mutation in block 2. The luciferase assay revealed that the priming activity of the CA haplotype in block 2 was the highest. 4. Taken together, the rs315692306, 2:g43385123, rs735854102, 2:g43385457 and rs737907370 in the 5ʹ regulatory region of the CTNNB1 gene have significant impacts on egg production.

The Potential of Jatropha variegata Fruits as a Natural Contraceptive: Antifertility Activity and Phytochemical Analysis.

Background Jatropha variegata (family, Euphorbiaceae) is native to Yemen, where it is commonly known as the Ebki shrub. The fruits of the plant are traditionally ingested by local women as a natural method of contraception. This study was undertaken to investigate the phytochemical content of the methanol extract of J. variegata fruits and to evaluate its antifertility potential. Methods Isolation of the chemical constituents was performed by chromatographic techniques, and the chemical structures of these compounds were identified by spectroscopy. The antifertility activity of the methanol extract was assessed in two experimental rat models to explore both the anti-implantation and the estrogenic/antiestrogenic activities in females. In these models, the number of successful implants, the size of litter, and body/ovary weights were all recorded. The development of ovarian follicles was also monitored via histological staining. Results Phytochemical work on the fruit extract of J. variegata led to the isolation of two oils (JF1 and JF2) and methyl elaidate. GC-MS analysis of the JF1 oil revealed that the major chemical constituents were fatty acid esters (43.77%), hydrocarbon alkanes (20.65%), and terpenoids (4.65%), while terpenoids (28.8%), fatty acids and their esters, (29.47%), and phytosterol (10.49%) were the major components found in the JF2 oil. The methanol extract of J. variegata fruit exhibited 50% and 93% abortifacient activity at 150 and 300 mg/kg doses, respectively. The extract also showed significant estrogenic activity as evidenced by the increase in rat ovary weight at a dose of 300 mg/kg compared to the control group. Histological analyses further confirmed this estrogenic activity. Conclusions J. variegata fruits possess an antifertility activity that appeared to result from its antiembryo implantation potential and from its estrogenic activity. The bioactive constituents involved in these activities may need to be further explored and exploited in the pursuit of newer contraceptives.

Effects of Jatropha curcas seed extract on reproductive functions in female Wistar rats

Background: Jatropha curcas is a multipurpose plant with several industrial and medicinal importance. Its seeds contain many active compounds that are used as medicines with antiinflammatory, and antioxidant activity. Objective: The objective of this study is to evaluate the effects of extract of Jatropha curcas seed which is patronized locally in some communities as agent of preventing childbirth on reproductive functions in female Wistar rats. Methods: Twenty-four animals were randomly divided into four groups of 6 rats each. Group I was administered normal saline and served as control. Groups II, III and IV were given the seed extract orally at doses of 100mg/kg, 200mg/kg and 400mg/kg body weight respectively daily for 14days orally. The animals were euthanised and blood samples collected for oestrogen, progesterone, FSH and LH assay. Statistical analysis was done using statistical package for social sciences (SPSS). Differences in means was obtained using ANOVA test. All values reported in the study were expressed as mean ± SEM. Differences in mean was taken to be significant at P<0.05. Results: There was significant reduction (p<0.05) in levels of progesterone, LH and FSH in moderate and high doses of the extract. But estrogen level was significantly (p<0.05) decreased in both low and moderate doses, while the high dose showed significant (p<0.05) increase. Conclusion: There was alteration in reproductive hormones due to arrest of development of ovarian follicles. This gives it the propensity of exhibiting contraceptive activity. J Bngladesh Soc Physiol 2021;16(1): 104-110

Averaging of a Stochastic Slow-Fast Model for Population Dynamics: Application to the Development of Ovarian Follicles

We analyze a birth, migration, and death stochastic process modeling the dynamics of a finite population, in which individuals transit unidirectionally across successive compartments. The model is formulated as a continuous-time Markov chain, whose transition matrix involves multiscale effects; the whole (or part of the) population affects the rates of individual birth, migration, and death events. Using the slow-fast property of the model, we prove the existence and uniqueness of the limit model in the framework of stochastic singular perturbations. The derivation of the limit model is based on compactness and coupling arguments. The uniqueness is handled by applying the ergodicity theory and studying a dedicated Poisson equation. The limit model consists of an ordinary differential equation ruling the dynamics of the first (slow) compartment, coupled with a quasi-stationary distribution in the remaining (fast) compartments, which averages the contribution of the fast component of the Markov chain on the slow one. We illustrate numerically the convergence and highlight the relevance of dealing with nonlinear event rates for our application in reproductive biology. The numerical simulations involve a simple integration scheme for the deterministic part, coupled with the nested algorithm to sample the quasi-stationary distribution.

Modulation of atrial natriuretic peptide receptors in ovarian folliculogenesis

Specific receptors for atrial natriuretic peptide (ANP) located in intra-ovarian tissues are suggested to be involved in ovarian functions such as oocyte maturation and follicle development. However, the characteristics and modulation of its receptor in relation to ovarian folliculogenesis are not well defined. This study examined the properties of ANP receptors in the ovary using quantitative receptor autoradiography. In the pig ovary, the highest binding sites for 125I-ANP(1-28) were localized in the granulosa cell layer of the follicles as well as cumulus oophorous. The binding sites for 125I-ANP(1-28) on theca layer of the ovarian follicles were mainly localized in the external layer, but none was observed in the internal layer. Specific binding of 125I-ANP(1-28) was not found clearly in atretic follicles. In the corpus luteum, the binding site was not observed. Analysis of the competitive inhibition of the binding of 125I-ANP(1-28) to the granulosa and theca externa layers in various preovulatory follicles by increasing concentrations of unlabeled ANP(1-28) was consistent with a single high affinity for 125I-ANP(1-28). The maximal binding capacities of 125I-ANP(1-28) in granulosa layer were significantly increased in proportion to the development of ovarian follicles. However, no significant difference of binding capacities of 125I-ANP(1-28) was observed in theca externa layer. The binding affinities of 125I-ANP(1-28) in granulosa and theca externa layers were not different from each other. Especially, the correlation between specific binding of 125I-ANP(1-28) and follicle diameter. A significant correlation was revealed between specific binding of 125I-ANP(1-28) and follicle diameter (R = 0.88, p < 0.0001) in granulosa layer, however, less relationship was detected in theca externa layer (R = 0.50, p < 0.0001). Therefore, these results indicate that the biological ANP receptors exist in granulosa and the theca externa layers of the pig ovary, and suggest that the ANP receptors in granulosa layer may be related to the regulatory function of the ovarian follicullogenesis including oocyte maturation.

The opposite effects of VGLL1 and VGLL4 genes on granulosa cell proliferation and apoptosis of hen ovarian prehierarchical follicles

Transcription cofactors Vestigial like family (VGLL) members consisting of four homologs (VGLL1-4) are associated with cell growth and metastasis in mammals, among which VGLL1 gene has been documented to possess tumorigenic functions in various types of tumor, and VGLL4 acts as a new tumor suppressor; likewise several studies indicated that they potentially play a role in the regulation of ovary growth and function. However, the biological effects of chicken VGLL1 and VGLL4 on the proliferation, apoptosis, and steroidogenesis of the granulosa cells (GCs) during ovarian follicle development remain unknown now. This study found that VGLL1 and VGLL4 genes present divergent expression patterns of the transcripts in the GCs of various sized prehierarchical follicles (PFs) before follicle selection. Specific small interfering RNA (siRNA) was employed to elucidate the exact roles of VGLL1 and VGLL4 in regulating the PF development of the hen ovary. The results demonstrated that the mRNA expression levels of the steroidogenic-related enzyme steroidogenic acute regulatory protein (STAR) gene and the cell proliferation-related factors B-cell lymphoma-2 (BCL2), and cyclin D1 (CCND1) genes were significantly down-regulated in the cells with VGLL1 silence but remarkably up-regulated in the cells lacking VGLL4. Whereas the expression level of the cell apoptosis biomarker caspase-3 (CASP3) transcript was noticeably enhanced in the GCs without VGLL1 but significantly decreased in the GCs deprived of VGLL4. Further results showed that the siRNA-mediated silence of VGLL1 caused a significant increase in apoptosis with a reduction in the proliferation of GCs. Nevertheless, knockdown of VGLL4 resulted in a remarkable decrement in apoptosis but a memorable augment in proliferation of the GCs. Taken together, this study proved that VGLL1 promotes cell proliferation and steroidogenesis but inhibits apoptosis. In contrast, VGLL4 stimulates GC apoptosis while suppressing the GC proliferation and steroidogenesis in the hen ovarian follicles. We conluded that VGLL1 and VGLL4 affect oppositely the ovarian prehierarchical follicle development by the different regulatory manner in the GC proliferation and apoptosis of chicken ovary.

Concentrated ambient fine particles exposure affects ovarian follicle development in mice

BackgroundAmbient fine particles (PM2.5) are known to cause various reproductive and developmental diseases. However, the potential mechanisms of PM2.5 exposure induced female reproductive damage remain unclear. MethodsFour weeks old female C57BL/6 J mice were exposed to filtered air (FA, n = 10) or concentrated ambient PM2.5 (CAP, n = 10) using a versatile aerosol concentration enrichment system. After 9 weeks of the exposure, mice were sacrificed under sevoflurane anesthesia and tissue samples were collected. Immunohistochemical analysis, enzyme-linked immunosorbent assay, quantitative polymerase chain reaction, and RNA-sequencing were performed to analyze the effects of PM2.5 exposure on follicle development and elucidate its potential mechanisms. ResultsChronic PM2.5 exposure resulted in follicular dysplasia. Compared to the FA-exposed group, follicular atresia in the CAP-exposed mice were significantly increased. Further studies confirmed that CAP induced apoptosis in granulosa cells, accompanied by a distortion of hormone homeostasis. In addition, RNA-sequencing data demonstrated that CAP exposure induced the alteration of ovarian gene expressions and was associated with inflammatory response. ConclusionsChronic exposure to CAP can induce follicular atresia, which was associated with hormone modulation and inflammation.

Effects of hypercaloric diet-induced hyperinsulinemia and hyperlipidemia on the ovarian follicular development in mice.

Long-term hypercaloric diets may adversely affect the development of ovarian follicles. We investigated the effects of high sugar (HS), high fat low sugar (HFLS), and high fat normal sugar (HFNS) diets on the ovarian follicle development in mice fed with these diets as compared to those fed with normal diet (control) for 180 days. Body weight, gonadal fat, glucose, lipid, insulin, estrous cycle, sex hormones and ovarian tissues were examined, and metabolism-related protein expression in the ovaries was evaluated by immunoblotting. The mice fed with hypercaloric diets showed hyperinsulinemia and hyperlipidemia, and exhibited heavier body and gonadal fat weights, longer estrous cycles, and fewer preantral and antral follicles than mice fed with normal diet. The sex hormone levels in the blood were similar to those in controls, except for significantly elevated estradiol levels in the HS diet group. The AMPKα phosphorylation was reduced, while AKT phosphorylation and caspase-3 levels were increased in the ovarian tissues of mice in all three hypercaloric diet groups than those in control. Taken together, the results suggest hyperinsulinemia and hyperlipidemia as possible mechanisms that impair the development of ovarian follicles in response to long-term exposure to unhealthy hypercaloric diets.

Yap is essential for uterine decidualization through Rrm2/GSH/ROS pathway in response to Bmp2.

Yap is required for ovarian follicle and early embryo development, but little information is available regarding its physiological significance in decidualization. Here we determine the effects of YAP on decidualization, mitochondrial function, cell apoptosis and DNA damage, and explore its interplay with Bmp2, Rrm2, GSH and ROS. The results exhibited that Yap was abundant in decidual cells and its inactivation impaired the proliferation and differentiation of stromal cells along with the deferral of G1/S phase transition, indicating Yap importance in decidualization. Bmp2 via Alk2 receptor promoted nuclear translocation of Yap where it might interact with Tead and then bind to the promoter of Rrm2 whose activation rescued the faultiness of differentiation program and attenuated oxidative DNA damage caused by Yap impediment. Meanwhile, Yap had an important part in the crosstalk between Bmp2 and Rrm2. Furthermore, inactivation of Yap resulted in an obvious accumulation of intracellular ROS followed by the abnormal GR activity and GSH content dependent on Rrm2. Replenishment of GSH counteracted the regulation of Yap inactivation on stromal differentiation and DNA damage with distinct reduction for intracellular ROS. Additionally, blockage of Yap caused the enhancement of stromal cell apoptosis and brought about mitochondrial dysfunction as indicated by the aberration for ATP level, mtDNA copy number and mitochondrial membrane potential concomitant with the opening of mitochondrial permeability transition pore, but these abnormalities were neutralized by GSH. Administration of mitochondrial antioxidant Mito-TEMPO rescued the fault of stromal differentiation conferred by Yap inactivation. Collectively, Yap was essential for uterine decidualization through Rrm2/GSH/ROS pathway in response to Bmp2.

Expression and regulation of estrogen receptor 2 and its coregulators in mouse granulosa cells.

The cooperative effects of estrogen and oocyte-derived paracrine factors (ODPFs) play critical roles in the normal development of ovarian follicles; however, the mechanism underlying this cooperation has not been well studied. The present study aimed to determine whether ODPFs affect estrogen signaling by regulating the expression of estrogen receptor (ESR) and its coregulators in mouse granulosa cells. Some transcripts encoding ESR coregulators were differentially expressed between cumulus and mural granulosa cells (MGCs). The transcript levels of ESR coregulators, including nuclear receptor corepressor 1 and activator 2, in cumulus cells were significantly suppressed by ODPFs; however, they increased when cumulus cell-oocyte complexes were treated with the transforming growth factor beta receptor I inhibitor, SB431542. Moreover, MGCs exhibited significantly higher ESR2 protein and transcript levels than those in cumulus cells. ODPFs promoted Esr2 expression in cumulus cells but had no effect on that in MGCs. Overall, regulation of the expression of ESR2 and its coregulators in cumulus cells by oocytes seems to be one of the mechanisms underlying estrogen-oocyte cooperation in well-developed antral follicles in mice.

Rapamycin maintains the primordial follicle pool and protects ovarian reserve against cyclophosphamide-induced damage.

Any abnormal activation of primordial follicles and subsequent depletion can irreversibly diminish the ovarian reserve, which is one of the major chemotherapy-induced adverse effects in young patients with cancer. Herein, we investigated the effects of rapamycin on the activation and development of ovarian follicles to evaluate its fertility-sparing therapeutic value in a cyclophosphamide (CTX)-treated mouse model. Based on ovarian histomorphological changes and follicle counting in 50 SPF female C57BL/6 mice, daily administration of 5 mg/kg rapamycin for 30 days was deemed an ideal dosage and duration for administration in subsequent experiments. Compared with the control group, rapamycin treatment inhibited the activation of quiescent primordial follicles, with no obvious side effects observed. Finally, 48 mice were randomly divided into four groups: control, rapamycin-treated, cyclophosphamide-treated, and rapamycin intervention. Body weight, ovarian histomorphological changes, number of primordial follicles, DDX4/MVH expression, apoptosis of follicular cells, and expression of apoptosis protease-activating factor (APAF)-1, cleaved caspase 3, and caspase 3 were monitored. Co-administration of rapamycin reduced primordial follicle loss and the development of follicular cell apoptosis, thereby rescuing the ovarian reserve after CTX treatment. On analyzing the mTOR signaling pathway, we observed that rapamycin significantly decreased CTX-mediated overactivation of mTOR and its downstream molecules. These findings suggest that rapamycin exhibits potential as an ovarian-protective agent that could maintain the ovarian primordial follicle pool and preserve fertility in young female patients with cancer undergoing chemotherapy.

Melatonin Protects the Histologic Structure of the Uterus in Conditions of Zearalenone Intake.

Background:Zearalenone is a widely spread mycotoxin, contaminant of most cereal grains. It has uterotropic, estrogenic and anabolic activity in farm animals. The results are hormonal disbalances as hyperestrogenism, Zearalenone inhibits follicle-stimulating hormone production, thus supressing ovarian follicle development and ovulation. Also, it induces oxidative stress. Melatonin acts as a potent natural antioxidant and regulates the reproductive function by modification of steroidogenesis.Objective:The present study was conducted to provide detailed qualitative histological analysis of uterus of female rats treated with zearalenone and melatonin and contribute to better understanding of the topic.Methods:Forty adult, female Wistar rats were equally divided into five groups: Z group – zearalenone, 0,3 mg/kg, i.g.; M group – melatonin, 10 mg/kg, i.p.; ZM group –concomitant application of zearalenone and melatonin in the same dosing regimen, VZ group–zearalenone vehiculum/sunflower oil, i.g. and MZ group–melatonin vehiculum/5% ethanol in Ringer, i.p. Animals were treated daily for 28 consecutive days. After that period, all animals were sacrificed to obtain samples for qualitative histological analysis using the light microscope.Results:Zearalenone led to the alterations of the uterine structures, predominantly in the endometrium that were characterized by metaplasia and hypertrophy of the epithelial cells and hypercellularity of the stroma. In the myometrium, zearalenone induced hypertrophy and hyperplasia of the myocytes.Conclusion:Melatonin, when applied together with zearalenone, blocked the adverse effects of the zearalenone.

The role of 25 hydroxycholecalciferol (VITD3) on insulinandndash; resistance in patients with polycystic ovary syndrome (PCOS)

Background: Polycystic ovary syndrome (PCOS) is the greatest frequent endocrine syndrome in females, giving with numerous likely mixtures of symptoms and signs and a variety of phenotypes, which might contain generative, endocrine, and metabolic modifications. PCOS is characterized by hypothalamic–pituitary– ovary axis dysfunction and anovulation ovulatory dysfunction can still occur with regular cycles and if anovulation needs to be confirmed serum progesterone levels can be measured but, unlike other causes of ovulatory disappointment that feature inadequate ovarian follicle development or repressed gonadotropin emission, PCOS typically includes androgen excess and subtle alterations in serum levels of gonadotropins and estrogens. Objective: demonstrate and compare therapeutic effect of vitamin D; supplementation on the metabolism and endocrine parameters of polycystic ovary syndrome patients with insulin- resistance. Subjective: The study was carried out on 86 patients, divided into 2 groups, group A treated by vitamin D supplement, while group B treated by placebo. Results: The fasting blood sugar was significant decreased in the two studied groups. HOMA IR shows a significant decrease in the two studied groups after treatment but in group A “vitamin D supplement” decrease by a highly significant degree than the placebo group. SHBG show a significant increase in both studied groups, after treatment there was a slight increase in group A more than group B in SHBG but this increase was insignificant. Vitamin D induces the transcription of HOXA10 through vitamin D receptors. Managenent with vitamin D rises mRNA and protein appearance of HOXA10. Vitamin D too has a straight influence on the rule of HOXA10, and this has implications for fertility. Conclusion: A significant effects of vitamin D supplementation on either metabolic or endocrine parameters in our study of PCOS women with insufficient baseline 25(OH)D concentrations.

Farklı Gelişim Dönemlerindeki Ovaryum Foliküllerinde Pro ve Anti-Apoptotik Bax ve Bcl-2'nin Dağılım ve Ekspresyon Düzeyinin İncelenmesi

Background: In this study we aimed to investigate the distribution and expression level of pro and anti-apoptotic proteins, Bax and Bcl-2, in different developmental stages of ovarian follicles and any relations between these proteins and follicle atresia. Materials and Methods: For that purpose, bilateral 16 ovaries of adult 8 mice were received and the tissues were fixed in 10% neutral buffered formalin. Routine tissue processing protocol was performed and the samples were embedded into paraffin blocks. Five µm thick sections were received and the tissue sections were stained with Bax and Bcl-2 immunohistochemistry. The ovarian follicles were classified as primordial, primary, secondary and antral. Distribution and expression levels of Bax and Bcl-2 were evaluated among and within the developmental stages. The expression levels of Bax and Bcl-2 were also compared with atretic follicle ratio. Results: Immunopositivity of Bax and Bcl-2 were observed in ovarian stromal cells, granulosa, oocytes, and lutheal cells in a varying range. Despite of some immunpositivity, most of the primordial and primary follicle granulosa cells and oocytes were negative for these apoptosis regulator proteins. The intensity of immunopositivity increased at the farther developmental process in follicles. In addition, the immunoexpression level significantly increased just with the beginning of the secondary follicular stage and the expression levels were the most intense in antral follicles. Furthermore, some of the antral follicles were intense Bax positive which were observed with atretic follicle morphology. Conclusions: Bax and Bcl-2 are crucial regulators of ovarian follicle development. Although Bcl-2 contributes on development, correlation analyses indicated that Bax decides stronger than Bcl-2 on the atresia or development fate of follicle.

Addition of a carboxy-terminal tail to the normally tailless gonadotropin-releasing hormone receptor impairs fertility in female mice.

Gonadotropin-releasing hormone (GnRH) is the primary neuropeptide controlling reproduction in vertebrates. GnRH stimulates follicle-stimulating hormone (FSH) and luteinizing hormone (LH) synthesis via a G-protein-coupled receptor, GnRHR, in the pituitary gland. In mammals, GnRHR lacks a C-terminal cytosolic tail (Ctail) and does not exhibit homologous desensitization. This might be an evolutionary adaptation that enables LH surge generation and ovulation. To test this idea, we fused the chicken GnRHR Ctail to the endogenous murine GnRHR in a transgenic model. The LH surge was blunted, but not blocked in these mice. In contrast, they showed reductions in FSH production, ovarian follicle development, and fertility. Addition of the Ctail altered the nature of agonist-induced calcium signaling required for normal FSH production. The loss of the GnRHR Ctail during mammalian evolution is unlikely to have conferred a selective advantage by enabling the LH surge. The adaptive significance of this specialization remains to be determined.

Cumulus Extracellular Matrix Is an Important Part of Oocyte Microenvironment in Ovarian Follicles: Its Remodeling and Proteolytic Degradation.

The extracellular matrix (ECM) is an essential structure with biological activities. It has been shown that the ECM influences gene expression via cytoskeletal components and the gene expression is dependent upon cell interactions with molecules and hormones. The development of ovarian follicles is a hormone dependent process. The surge in the luteinizing hormone triggers ovulatory changes in oocyte microenvironment. In this review, we discuss how proteolytic cleavage affects formation of cumulus ECM following hormonal stimulation; in particular, how the specific proteasome inhibitor MG132 affects gonadotropin-induced cytoskeletal structure, the organization of cumulus ECM, steroidogenesis, and nuclear maturation. We found that after the inhibition of proteolytic cleavage, gonadotropin-stimulated oocyte–cumulus complexes (OCCs) were without any signs of cumulus expansion; they remained compact with preserved cytoskeletal F-actin-rich transzonal projections through the oocyte investments. Concomitantly, a significant decrease was detected in progesterone secretion and in the expression of gonadotropin-stimulated cumulus expansion–related transcripts, such as HAS2 and TNFAIP6. In agreement, the covalent binding between hyaluronan and the heavy chains of serum-derived the inter-alpha-trypsin inhibitor, essential for the organization of cumulus ECM, was missing.

CPEB3 deficiency in mice affect ovarian follicle development and causes premature ovarian insufficiency

Premature ovarian insufficiency (POI) is a heterogeneous and multifactorial disorder. In recent years, there has been an increasing interest in research on the pathogenesis and treatment of POI, owing to the implementation of the second-child policy in China. Cytoplasmic polyadenylation element-binding protein 3 (CPEB3) is an RNA-binding protein that can bind to specific RNA sequences. CPEB3 can bind to and affect the expression, cellular location, and stability of target RNAs. Cpeb3 is highly expressed in the ovary; however, its functions remain unknown. In this study, Cpeb3-mutant mice were used to characterize the physiological functions of CPEB3. Cpeb3-mutant female mice manifested signs of gradual loss of ovarian follicles, ovarian follicle development arrest, increased follicle atresia, and subfertility with a phenotype analogous to POI in women. Further analysis showed that granulosa cell proliferation was inhibited and apoptosis was markedly increased in Cpeb3-mutant ovaries. In addition, the expression of Gdf9, a potential target of CPEB3, was decreased in Cpeb3-mutant ovaries and oocytes. Altogether, these results reveal that CPEB3 is essential for ovarian follicle development and female fertility as it regulates the expression of Gdf9 in oocytes, disruption of which leads to impaired ovarian follicle development and POI.

Hemodynamic, endocrine, and gene expression mechanisms regulating equine ovarian follicular and cellular development.

Ovulatory follicle development and associated oocyte maturation involve complex coordinated molecular and cellular mechanisms not yet fully understood. This study addresses the relationships among follicle diameter, follicle wall blood flow, follicular-fluid factors, and gene expression for follicle growth, steroidogenesis, angiogenesis, and apoptosis in granulosa/cumulus cells and oocytes during different stages from the beginning of largest/ovulatory follicle to impending ovulation in mares. The most remarkable findings were (i) a positive association between follicle development, follicle blood flow, intrafollicular follicle-stimulating hormone (FSH), luteinizing hormone (LH), estradiol, progesterone, and messenger RNA (mRNA) expression for FSHR and LHCGR in granulosa cells of the largest/ovulatory follicle; (ii) a plateau or decrease in follicle diameter and blood flow and granulosa cell mRNA for FSHR, LHCGR, IGF1R, VEGFR2, CYP19A1, and CASP3 at the preovulatory stage; (iii) higher StAR and BCL2 and lower CASP3 mRNA in granulosa cells at the time of impending ovulation; (iv) greater IGF1R mRNA for granulosa cells at the predeviation stage; and (v) lower FSHR, LHCGR, IGF1R, and VEGFR2 mRNA in cumulus cells and greater LHCGR and IGF1R mRNA in oocytes at the ovulatory stage. This study is a critical advance in the understanding of molecular mechanisms of follicle development and oocyte maturation and is expected to be vital for future studies targeting potential markers.

Insulin-like growth factor 2 (IGF2) gene: molecular characterization, expression analysis and association of polymorphisms with egg production traits in goose (Anser cygnoides)

Insulin-like growth factor 2 (IGF2) belongs to the member of the insulin-like growth factors family, which plays key roles in animal growth, differentiation and proliferation, as well as reproduction and the regulation of ovarian follicle development. However, little is known about the goose IGF2 gene. In this study, a 1879 bp fragment that covered the complete coding region (CDS) of goose IGF2 cDNA was identified for the first time. The cDNA consists of an open reading frame of 574 nucleotides with the capacity to encode a prepro-IGF-II protein of 187 amino acids, which comprises a signal peptide (24 residues), IGF-II peptide (67 residues), and C-terminal peptide (96 residues), and is closely related to that of chicken. qPCR indicates that the goose IGF2 mRNA is differentially expressed in all examined tissues of fertilized eggs (28 days) and laying Zhedong White geese (270 days). Two novel single nucleotide polymorphisms (SNPs) were detected in exon 1 (G63A, Chr2: G26541617A) and intron 1 (G38A, Chr2: G26541479A) regions, and the synonymous mutation G63A showed a significant association with egg numbers (E180d) of Sanhua goose population (p < 0.05). All the information derived from this study could be valuable and facilitate further studies on the functions of goose IGF2 gene.