Kit ligand and c-Kit have diverse roles during mammalian oogenesis and folliculogenesis

KIT in oocytes: a key factor for oocyte survival and reproductive lifespan

BACKGROUND

The KITL-KIT interaction is known as an important initiator in oocyte activation through the downstream pathway of PI3K-AKT-FOXO3 signalling. Previous studies utilising germ cell-specific Kit mutant knockin and kinase domain knockout models with Vasa-Cre suggested the crucial role of KIT in oocyte activation at the primordial follicle stage.

METHODS

We utilised mice with complete postnatal deletion of KIT expression in oocytes via Gdf9-iCre and conducted analyses on ovarian follicle development, specific markers, hormone assays, and fertility outcomes.

FINDINGS

Our findings reveal contrasting phenotypes compared to previous mouse models with prenatal deletion of Kit. Specifically, postnatal deletion of Kit exhibit no defects in germ cell nest breakdown, follicle activation, and folliculogenesis during development. Remarkably, upon reaching full maturity, mice with postnatal deletion of Kit experience a complete loss of ovarian reserve, growing follicles, and ovarian function. Furthermore, mice display smaller ovarian size and weight, delayed folliculogenesis, and phenotypes indicative of primary ovarian insufficiency (POI), including elevated serum levels of FSH, reduced AMH, and absence of ovarian follicles, ultimately resulting in infertility. Additionally, the ovaries exhibit randomly distributed expression of granulosa and theca cell markers such as Inhibin α, ACVR2B, and LHR. Notably, there is the uncontrolled expression of p-SMAD3 and Ki67 throughout the ovarian sections, along with the widespread presence of luteinised stroma cells and cleaved Caspase-3-positive dying cells.

INTERPRETATION

These genetic studies underscore the indispensable role of KIT in oocytes for maintaining the survival of ovarian follicles and ensuring the reproductive lifespan.

FUNDING

This work was supported by National Institutes of Health grant R01HD096042 and startup funds from UNMC (S.Y.K.).

Fertility and reproductive concerns related to the new generation of cancer drugs and the clinical implication for young individuals undergoing treatments for solid tumors

The treatment landscape of solid tumors has changed markedly in the last years. Molecularly targeted treatments and immunotherapies have been implemented and have, in many cancers, lowered the risk of relapse and prolonged survival. Patients with tumors harboring specific targetable molecular alterations or mutations are often of a younger age, and hence future fertility and family building can be important concerns in this group. However, there are great uncertainties regarding the effect of the new drugs on reproductive functions, including fertility, pregnancy and lactation and how young patients with cancers, both women and men should be advised. The goal with this review is to gather the current knowledge regarding oncofertility and the different novel therapies, including immune checkpoint inhibitors, antibody-drug conjugates, small molecules and monoclonal antibody targeted therapies. The specific circumstances and reproductive concerns in different patient groups where novel treatments have been broadly introduced are also discussed, including those with melanoma, lung, breast, colorectal and gynecological cancers. It is clear, that more awareness is needed regarding potential drug toxicity on reproductive tissues, and it is of essence that individuals are informed based on current expertise and on available fertility preservation methods.

Ovarian nesfatin-1 in Hemidactylus flaviviridis: Reproductive phase-dependent expression, role and hormonal regulation

Nesfatin-1 has recently emerged as a modulator of ovarian functions in mammals. Studies in non-mammalian vertebrates, though limited and majorly restricted to fishes, have evidenced a role of this peptide in the regulation of ovarian steroidogenesis and oocyte maturation. Interestingly, nesfatin-1 remains completely unexplored in reptiles. Therefore, the present study aimed to identify nesfatin-1 and elucidate its role and regulation in the ovary of Hemidactylus flaviviridis. Ovarian expression of nucb2/nesfatin-1 was highest during late recrudescence and breeding while it was lowest during regression. Follicular stage-dependent expression analysis showed significantly high expression of nucb2/nesfatin-1 in previtellogenic follicles. Further, in vitro treatment of recrudescent wall lizard ovaries with nesfatin-1 resulted in increased expression of anti-apoptotic gene, bcl-2, along with a concomitant decline in the pro-apoptotic gene, caspase-3. In addition, proliferation/differentiation markers like scf, c-kit, pcna, and bmp-15 were stimulated in ovaries incubated with the peptide. Ovarian steroidogenesis was also positively influenced by nesfatin-1 as treatment with the peptide resulted in heightened star expression as well as increased estradiol and progesterone production. Also, all concentrations of nesfatin-1 stimulated glucose uptake and metabolism in wall lizard ovary. Our observations provide the first evidence of ovarian functions of nesfatin-1 in a reptile. Further, ovarian nucb2/nesfatin-1 was differentially regulated by gonadotropin and sex steroids wherein its expression was stimulated by dihydrotestosterone (DHT) and 17β-estradiol (E2) but inhibited by follicle-stimulating hormone (FSH). In summary, this is the first report of the presence, reproductive stage-dependent expression, role, and regulation of ovarian nucb2/nesfatin-1 in H. flaviviridis.

Low dose rate radiation impairs early follicles in young mice

Low-dose radiation is generally considered less harmful than high-dose radiation. However, its impact on ovaries remains debated. Since previous reports predominantly employed low-dose radiation delivered at a high dose rate on the ovary, the effect of low-dose radiation at a low dose rate on the ovary remains unknown. We investigated the effect of low-dose ionizing radiation delivered at a low dose rate on murine ovaries. Three- and ten-week-old mice were exposed to 0.1 and 0.5 Gy of radiation at a rate of 6 mGy/h and monitored after 3 and 30 days. While neither body weight nor ovarian area showed significant changes, ovarian cells were damaged, showing apoptosis and a decrease in cell proliferation after exposure to 0.1 and 0.5 Gy radiation. Follicle numbers decreased over time in both age groups proportionally to the radiation dose. Younger mice were more susceptible to radiation damage, as evidenced by decreased follicles in 3-week-old mice after 30 days of 0.1 Gy exposure, while 10-week-old mice showed reduced follicles only following 0.5 Gy exposure. Primordial or primary follicles were the most vulnerable to radiation. These findings suggest that even low-dose radiation, delivered at a low dose rate, can adversely affect ovarian function, particularly in the early follicles of younger mice.

Cell-cell interactions during the formation of primordial follicles in humans

Gametogenesis is a complex and sex-specific multistep process during which the gonadal somatic niche plays an essential regulatory role. One of the most crucial steps during human female gametogenesis is the formation of primordial follicles, the functional unit of the ovary that constitutes the pool of follicles available at birth during the entire reproductive life. However, the relation between human fetal germ cells (hFGCs) and gonadal somatic cells during the formation of the primordial follicles remains largely unexplored. We have discovered that hFGCs can form multinucleated syncytia, some connected via interconnecting intercellular bridges, and that not all nuclei in hFGC-syncytia were synchronous regarding meiotic stage. As hFGCs progressed in development, pre-granulosa cells formed protrusions that seemed to progressively constrict individual hFGCs, perhaps contributing to separate them from the multinucleated syncytia. Our findings highlighted the cell-cell interaction and molecular dynamics between hFGCs and (pre)granulosa cells during the formation of primordial follicles in humans. Knowledge on how the pool of primordial follicle is formed is important to understand human infertility.

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.

Discovery of potential FGFR3 inhibitors via QSAR, pharmacophore modeling, virtual screening and molecular docking studies against bladder cancer

BACKGROUND

Fibroblast growth factor receptor 3 is known as a favorable aim in vast range of cancers, particularly in bladder cancer treatment. Pharmacophore and QSAR modeling approaches are broadly utilized for developing novel compounds for the determination of inhibitory activity versus the biological target. In this study, these methods employed to identify FGFR3 potential inhibitors.

METHODS

To find the potential compounds for bladder cancer targeting, ZINC and NCI databases were screened. Pharmacophore and QSAR modeling of FGFR3 inhibitors were utilized for dataset screening. Then, with regard to several factors such as Absorption, Distribution, Metabolism, Excretion and Toxicity (ADMET) properties and Lipinski's Rule of Five, the recognized compounds were filtered. In further step, utilizing the flexible docking technique, the obtained compounds interactions with FGFR3 were analyzed.

RESULTS

The best five compounds, namely ZINC09045651, ZINC08433190, ZINC00702764, ZINC00710252 and ZINC00668789 were selected for Molecular Dynamics (MD) studies. Off-targeting of screened compounds was also investigated through CDD search and molecular docking. MD outcomes confirmed docking investigations and revealed that five selected compounds could make steady interactions with the FGFR3 and might have effective inhibitory potencies on FGFR3.

CONCLUSION

These compounds can be considered as candidates for bladder cancer therapy with improved therapeutic properties and less adverse effects.

Oocyte Arrested at Metaphase II Stage were Derived from Human Pluripotent Stem Cells in vitro

Initiation of meiosis is the most difficult aspect of inducing competent oocytes differentiation from human stem cells in vitro. Human induced pluripotent stem cells (hiPSCs) and embryonic stem cells (hESCs) were cultured with follicle fluid, cytokines and small molecule to induced oocyte-like cells (OLCs) formation through a three-step induction procedure. Expression of surface markers and differentiation potential of germ cells were analyzed in vitro by flow cytometry, gene expression, immunocytochemistry, western blotting and RNA Sequencing. To induce the differentiation of hiPSCs into OLCs, cells were firstly cultured with a primordial germ cell medium for 10 days. The cells exhibited similar morphological features to primordial germ cells (PGCs), high expressing of germ cell markers and primordial follicle development associated genes. The induced PGCs were then cultured with the primordial follicle-like cell medium for 5 days to form the induced follicle-like structures (iFLs), which retained both primordial oocytes-like cells and granulosa-like cells. In the third step, the detached iFLs were harvested and transferred to the OLC-medium for additional 10 days. The cultured cells developed cumulus-oocyte-complexes (COCs) structures and OLCs with different sizes (50-150 μm diameter) and a zona pellucida. The in vitro matured OLCs had polar bodies and were arrested at metaphase II (MII) stage. Some OLCs were self-activated and spontaneously developed into multiple-cell structures similar to preimplantation embryos, indicating that OLCs were parthenogenetically activated though in vitro fertilization potential of OLCs are yet to be proved. in vitro maturation of OLCs derived from hiPSCs provides a new means to study human germ cell formation and oogenesis.

In vivo promotion of primordial follicle activation by stem cell factor treatment in mice with premature ovarian insufficiency and advanced age

Dormant primordial follicles (PFs) are the most abundant reproductive resource in mammalian ovaries. With advances in the mechanism of study of the regulation of PF activation, PFs have been used to improve fertility in clinical practice. As a central controlling element of follicle activation signaling, the pre-granulosa cell-secreted stem cell factor (SCF; also known as KIT ligand, KITL), which initiates the growth of dormant oocytes, is an ideal natural activator that stimulates follicle activation. However, no systematic study has been conducted to identify the activating effect of SCF in vivo and in vitro. In this study, by combining an in vitro whole ovary culture system and several mouse models, we provide a series of experimental evidence that SCF is an efficient activator for improving PF activation in mouse ovaries. Our in vitro study showed that SCF increased phosphatidylinositol 3-kinase (PI3K) signaling and PF activation ratio in neonatal ovaries. In vivo ovarian non-invasive topical administrations of SCF to the ovaries efficiently improved follicle activation and development, oocyte retrieval ratio and fertility in inducible premature ovarian insufficiency mouse models and aged mice. Our study suggests that SCF is an efficient growth factor that can be applied to improve PF activation.

Signaling pathway intervention in premature ovarian failure

Premature ovarian failure (POF) is a multifactorial disease that refers to the occurrence of secondary amenorrhea, estrogen decrease, and gonadotropin increase in women under the age of 40. The prevalence of POF is increasing year by year, and the existing instances can be categorized as primary or secondary cases. This disease has adverse effects on both the physiology and psychology of women. Hormone replacement therapy is the recommended treatment for POF, and a multidisciplinary strategy is required to enhance the quality of life of patients. According to recent studies, the primary mechanism of POF is the depletion of ovarian reserve function as a result of increased primordial follicular activation or primordial follicular insufficiency. Therefore, understanding the processes of primordial follicle activation and associated pathways and exploring effective interventions are important for the treatment of POF.

Potential ovarian toxicity and infertility risk following targeted anti-cancer therapies

Unlike traditional chemotherapy agents which are generally cytotoxic to all cells, targeted anti-cancer therapies are designed to specifically target proliferation mechanisms in cancer cells but spare normal cells, resulting in high potency and reduced toxicity. There has therefore been a rapid increase in their development and use in clinical settings, including in curative-intent treatment regimens. However, the targets of some of these drugs including kinases, epigenetic regulatory proteins, DNA damage repair enzymes and proteasomes, have fundamental roles in governing normal ovarian physiology. Inhibiting their action could have significant consequences for ovarian function, with potentially long-lasting adverse effects which persist after cessation of treatment, but there is limited evidence of their effects on reproductive function. In this review, we will use literature that examines these pathways to infer the potential toxicity of targeted anti-cancer drugs on the ovary.

Lay summary

Compared to traditional chemotherapy agents, anti-cancer therapies are thought to be highly effective at targeting cancer cells but sparing normal cells, resulting in reduced drug side effects. However, many of processes within the cells that these drugs affect are also important for the ovary to work normally, so suppressing them in this way could have long-lasting implications for female fertility. This review examines the potential toxicity of anti-cancer therapies on the ovary.

Impact of imatinib administration on the mouse ovarian follicle count and levels of intra-ovarian proteins related to follicular quality

Objective

The impact of imatinib, a tyrosine kinase inhibitor, on ovarian follicles and several proteins related to follicular function and apoptosis was investigated in mice.

Methods

Saline, cyclophosphamide (Cp; 50 or 75 mg/kg), or imatinib (7.5 or 15 mg/kg) was injected once intraperitoneally into female B6D2F1 mice (18 mice in each group). In multiple ovarian sections, the number of various types of follicles and the proportion of good-quality (G1) follicles were counted. The levels of six proteins (anti-Müllerian hormone [AMH], BCL-xL, BAX, acid sphingomyelinase [A-SMase], caspase-3, and α-smooth muscle actin [α-SMA]) within the whole ovaries were quantified using Western blots.

Results

Compared to the saline group, a significant reduction of the primordial follicle count was observed in the group treated with imatinib 7.5 and 15 mg/kg, as well as in the group treated with Cp 75 mg/kg. Administration of Cp significantly decreased the proportion of G1 primordial follicles, but administration of imatinib did not. No differences in the AMH, anti-apoptotic BCLX-L, pro-apoptotic BAX, and A-SMase levels in the ovarian tissues were observed among the five groups. However, caspase-3 and α-SMA levels were significantly higher in the imatinib and Cp groups than in the saline group.

Conclusion

The administration of imatinib to mice significantly reduced the primordial follicle count and increased the protein levels of caspase-3 and α-SMA. Our findings suggest that imatinib potentially exerts ovarian toxicity via apoptotic processes, similarly to Cp.

Targeted cancer treatment and fertility: effect of immunotherapy and small molecule inhibitors on female reproduction

Targeted cancer therapy is rapidly evolving the landscape of personalized health care. Novel approaches to selectively impeding tumour growth carry significant potential to improve survival outcomes, particularly for reproductive-aged patients harbouring treatment refractory disease. Current agents fall within two classes: immunotherapy and small molecule inhibitors. These are collectively divided into the following subclasses: monoclonal antibodies; immunomodulators; adoptive cell therapy; treatment vaccines; kinase inhibitors; proteasome inhibitors; metalloproteinase and heat shock protein inhibitors; and promoters of apoptosis. The short- and long-term effects of these treatments on the female reproductive system are not well understood. As a result, clinicians are rendered unable to appropriately counsel women on downstream effects to their fertility. Data-driven consensus recommendations are desperately needed. This review aims to characterize the effect of targeted cancer therapy on the female hypothalamic-pituitary-ovary axis, direct ovarian function and conception.

PI3K/PTEN/AKT Signaling Pathways in Germ Cell Development and Their Involvement in Germ Cell Tumors and Ovarian Dysfunctions

Several studies indicate that the PI3K/PTEN/AKT signaling pathways are critical regulators of ovarian function including the formation of the germ cell precursors, termed primordial germ cells, and the follicular pool maintenance. This article reviews the current state of knowledge of the functional role of the PI3K/PTEN/AKT pathways during primordial germ cell development and the dynamics of the ovarian primordial follicle reserve and how dysregulation of these signaling pathways may contribute to the development of some types of germ cell tumors and ovarian dysfunctions.

The safety of VASApos presumptive adult ovarian stem cells

Isolation and characterization of presumptive human adult ovarian stem cells (OSC) has broken the long standing dogma of the absence of postnatal neo-oogenesis. Human adult OSC have been immunosorted by antibodies reacting against the RNA helicase VASA and have been reported to engraft into appropriate stem cell niches to promote neo-oogenesis. Analysis of published research, however, questions some of the findings on isolation, characterization, in-vitro self-renewal and clinical safety of the presumptive human adult OSC. In the present study, human VASA^pos embryo-fetal primordial germ cells and presumptive adult OSC are shown to share several pluripotency and early germ cell markers not ascertained in the initial characterization of adult OSC. A new hypothesis is made that the restoration of fertility claimed to result from presumptive human adult OSC may be attributed instead to VASA^pos embryo-fetal primordial germ cell remnants in the adult ovary, or alternatively to earlier VASA^neg germ cells generated by in-vitro de-differentiation of the presumptive OSC. The suggested hypotheses have extensive implications for the practice and safety of adult OSC in the development of new treatments aimed at rescuing the ovarian reserve.

Where are the theca cells from: the mechanism of theca cells derivation and differentiation

Mammalian follicles are composed of oocytes, granulosa cells, and theca cells. Theca cells form in the secondary follicles, maintaining follicular structural integrity and secreting steroid hormones. Two main sources of theca cells exist: Wilms tumor 1 positive (Wt1⁺) cells native to the ovary and Gli1⁺ mesenchymal cells migrated from the mesonephros. Normal folliculogenesis is a process where oocytes, granulosa cells, and theca cells constantly interact with and support each other through autocrine and paracrine mechanisms. The proliferation and differentiation of theca cells are regulated by oocyte-derived factors, including growth development factor 9 and bone morphogenetic protein 15, and granulosa cell-derived factors, including desert hedgehog, Indian hedgehog, kit ligand, insulin-like growth factor 1, as well as hormones such as insulin and growth hormones. Current research on the origin of theca cells is limited. Identifying the origin of theca cells will help us to systematically elaborate the mechanisms of follicular formation and development.

Mural granulosa cells support to maintain the viability of growing porcine oocytes and its developmental competence after insemination

PURPOSE

To enhance the in vitro growth of porcine oocytes, we studied the effect of mural granulosa cells (MGCs) on the viability of oocytes attached to granulosa cells (oocyte-granulosa cell complexes, OGCs) that were obtained from early antral follicles.

METHODS AND RESULTS

When OGCs were cultured with MGCs for 12 days, there were significant improvement (P < 0.05) in the robustness of gap junctional communication between the oocyte and the granulosa cells (82% vs. 59%), the survival rate of oocytes (57% vs. 39%), and the diameter of survived oocytes (118 μm vs. 112 μm). The rate of oocyte release of OGCs cultured with MGCs on the 12th day (1.9%) was significantly lower than that of OGCs cultured without MGCs (26%). Complete meiotic arrest was maintained in the group with MGCs (100%), while partial resumption of spontaneous meiosis was noticed in the absence of MGCs (10-19%). Furthermore, the presence of MGCs increased the oocyte maturation rate after maturation culture in both 12- and 14-day culture groups (P < 0.05, 85-88%) compared to OGCs cultured without MGCs (48-60%). MGCs also significantly improved the blastocyst formation rate (day 7) after ICSI (P < 0.05).

CONCLUSIONS

The data of this study thus shows that the presence of MGCs during in vitro oocyte growth plays a crucial role in supporting the developmental competence of growing porcine oocytes attached to the granulosa cells via enhancement of their viability.

Effects of coenzyme Q10 on ovarian surface epithelium-derived ovarian stem cells and ovarian function in a 4-vinylcyclohexene diepoxide-induced murine model of ovarian failure

BACKGROUND

Several studies have shown that coenzyme Q10 (CoQ10) can rescue ovarian aging and that ovarian surface epithelium (OSE)-derived ovarian stem cells (OSCs) are useful for treating infertility due to ovarian aging. However, few studies have examined the effect of CoQ10 on OSCs. This study was aimed to investigate whether CoQ10 activates OSCs and recovers ovarian function in a 4-vinylcyclohexene diepoxide (VCD)-induced mouse model of ovarian failure.

METHODS

Forty female C57BL/6 mice aged 6 weeks were randomly divided into four groups (n = 10/group): a control group administered saline orally, a CoQ10 group administered 150 mg/kg/day of CoQ10 orally in 1 mL of saline daily for 14 days, a VCD group administered 160 mg/kg/day of VCD i.p. in 2.5 mL of saline/kg for 5 days, and a VCD + CoQ10 group administered VCD i.p. for 5 days injection and CoQ10 (150 mg/kg/day) orally for 14 days. After treatment, follicle counts were evaluated by hematoxylin and eosin (H&E) staining, and ovarian mRNA expressions of Bmp-15, Gdf-9, and c-Kit were examined by quantitative real-time PCR. Serum FSH, AMH, and ROS levels were also measured. Oocyte-like structure counts and the expressions of Oct-4 and MVH were also evaluated after culturing OSE for 3 weeks. In a second experiment, 32 female mice were administered CoQ10 as described above, induced to superovulate using PMSG and hCG, and mated. Numbers of zygotes and embryo development rate were examined.

RESULTS

Postcultured OSE showed significant increases in the numbers of oocyte-like structure and that the expression of Oct-4 and MVH were higher in the VCD + CoQ10 group than in the VCD group (p < 0.05). Numbers of surviving follicles from primordial to antral follicles, numbers of zygotes retrieved and embryo development rate to blastocyst were significantly greater in the VCD + CoQ10 group than in the VCD group (p < 0.01). Serum AMH level and ovarian expressions of Bmp-15, Gdf-9 and c-Kit were also significantly greater in the VCD + CoQ10 group than in the VCD group (p < 0.05). In contrast, serum ROS level was significantly lower in the VCD + CoQ10 group than in the VCD group (p < 0.05).

CONCLUSION

This study shows that CoQ10 stimulates the differentiation of OSE-derived OSCs and confirms that CoQ10 can reduce ROS levels and improve ovarian function and oocyte quality in mice with VCD-induced ovarian failure.

Abnormal early folliculogenesis due to impeded pyruvate metabolism in mouse oocytes†

Fetal ovarian germ cells show characteristic energy metabolism status, such as enhanced mitochondrial metabolism as well as glycolysis, but their roles in early folliculogenesis are unclear. We show here that inhibition of pyruvate uptake to mitochondria by UK5099 in organ cultures of fetal mouse ovaries resulted in repressed early folliculogenesis without affecting energy production, survival of oocytes, or meiosis. In addition, the abnormal folliculogenesis by UK5099 was partially rescued by α-ketoglutarate and succinate, intermediate metabolites in the TCA cycle, suggesting the importance of those metabolites. The expression of TGFβ-related genes Gdf9 and Bmp15 in ovarian germ cells, which are crucial for folliculogenesis, was downregulated by UK5099, and the addition of recombinant GDF9 partially rescued the abnormal folliculogenesis induced by UK5099. We also found that early folliculogenesis was similarly repressed, as in the culture, in the ovaries of a germ cell-specific knockout of Mpc2, which encodes a mitochondria pyruvate carrier that is targeted by UK5099. These results suggest that insufficient Gdf9 expression induced by abnormal pyruvate metabolism in oocytes results in early follicular dysgenesis, which is a possible cause of defective folliculogenesis in humans.

A case of ovarian stimulation for fertility preservation in a patient with Philadelphia chromosome-positive acute lymphoblastic leukemia after treatment with dasatinib

Tyrosine kinase inhibitors (TKIs) are effective for treating Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ALL). However, the use of TKIs may decrease the number of collected oocytes during fertility preservation procedures. We report the case of a 19-year-old patient with Ph+ALL for whom 21 oocytes were frozen after controlled ovarian stimulation was initiated 2 days after the completion of 28 days of remission induction therapy with dasatinib. After collecting the oocytes, consolidation therapy was initiated immediately, and a hematopoietic stem cell transplant from her younger brother was scheduled. It is believed that a 2-day withdrawal period is sufficient for fertility preservation or that the effect of dasatinib on the number of oocytes obtained is minimal.

Risks of molecular targeted therapies to fertility and safety during pregnancy: a review of current knowledge and future needs

INTRODUCTION

As the population of young cancer survivors is increasing and a trend toward postponing pregnancy later in life is reported, more efforts are focused toward understanding treatment-induced sequelae, in particular, the effects of cancer and/or treatment on fertility.

AREA COVERED

Whereas the fertility risk of cytotoxic agents for both men and women is well recognized, the impact of molecular-targeted therapy (MTT) on fertility parameters, their teratogenic potential and pregnancy outcome/management in case of an accidental exposure are not established. We update available clinical data on the impact of new MTTs on fertility in both sexes, their potential teratogenic effects and the outcome of pregnancy during accidental exposure. Agents are categorized by class and the potential relevance of their target signaling pathways to gonadal maturation.

EXPERT OPINION

The majority of MTTs have worrying preclinical data discouraging their use during pregnancy and reinforcing the idea that they can induce impairment in gonadal function. However, it does not mean that all MTTs result in permanent infertility and that they should be completely avoided during pregnancy. The current review provides a critical evaluation on the most commonly used MTTs, offering a possible guide for clinicians.

An overview of neuroblastoma cell lineage phenotypes and in vitro models

This review was conducted to present the main neuroblastoma (NB) clinical characteristics and the most common genetic alterations present in these pediatric tumors, highlighting their impact in tumor cell aggressiveness behavior, including metastatic development and treatment resistance, and patients' prognosis. The distinct three NB cell lineage phenotypes, S-type, N-type, and I-type, which are characterized by unique cell surface markers and gene expression patterns, are also reviewed. Finally, an overview of the most used NB cell lines currently available for in vitro studies and their unique cellular and molecular characteristics, which should be taken into account for the selection of the most appropriate model for NB pre-clinical studies, is presented. These valuable models can be complemented by the generation of NB reprogrammed tumor cells or organoids, derived directly from patients' tumor specimens, in the direction toward personalized medicine.

A novel variant in the promoter region of miR-9 gene strongly affects litter size in Markhoz goats

This study aimed to identify and evaluate the effects of single nucleotide polymorphisms (SNPs) within miR-9 and miR-27a genes and their promoters, as well as 3'UTR regions of KITLG and IGF1 genes on litter size in Markhoz goats. PCR-SSCP analysis revealed different band patterns and sequencing results confirmed four SNPs including a C/A, a A/G, a C/T and a A/G substitution located in the promoter region of miR-9 gene, 48 bp upstream of miR-9 seed region within the 3'UTR of KITLG gene, 37 bp downstream of miR-27a gene and 39 bp upstream of miR-9 seed region within the 3'UTR of IGF1 gene, respectively. The results of the least-square analyses indicated that AA genotype of miR-9 gene strongly and positively affects litter size in Markhoz goats (P < 0.01). Furthermore, the results of the logistic regression analyses confirmed that the A allele of miR-9 gene has a tremendous impact on litter size in Markhoz goats (P < 0.01). Scanning the promoter region of miR-9 gene showed that changing C allele to A may prevent HES1, HES2, NRF1 and TCFL5 transcription factors (TFs) from binding to the promoter, which can reduce the expression of miR-9 gene. Principle component analysis (PCA) showed that approximately 60% of the variation of the data set was explained by two of four SNPs. Also, the biplot from the PCA showed a strong association between litter size and C/A polymorphism of miR-9 promoter. Linkage disequilibrium analysis revealed a very slight linkage among investigated loci.

Successful ovarian stimulation and pregnancy in an infertile woman with chronic myeloid leukemia

BACKGROUND

Tyrosine kinase inhibitors (TKI) treatment has transformed chronic myeloid leukemia (CML) from a fatal neoplasm to a chronic disease with normal life expectancies. Indeed, half of CML patients are able to discontinue TKI without relapse. However, it seems clearly demonstrated that exposure to TKI may result in fetal malformations. Regarding its effects on fertility, preclinical studies and clinical case reports provide inconclusive evidence. Furthermore, due to the risk of CML relapse after TKI discontinuation, the optimal time to stop TKI represents a real dilemma.

CASE REPORT

We describe a 23-year-old woman who, after more than 6 years with imatinib and 1 year in deep molecular response [(DMR), MR ≥ 4], interrupted treatment to become pregnant. After 2 failed artificial insemination cycles, she underwent one process of controlled ovarian stimulation, achieving 2 blastocyst-embryos. In the meantime, BCR-ABL1^IS levels increased despite interferon-alpha therapy, she lost the mayor molecular response (MMR), and the 2 embryos had to be cryopreserved. A stable second MR ≥ 4.0 was again obtained with nilotinib, and after stopping it, the 2 blastocyst-embryo transfers were unsuccessfully performed. Under DMR, a second ovarian stimulation and in vitro fertilization (IVF) was performed and 1 blastocyst embryo was transferred. This time, she became pregnant and a healthy baby was born. After more than 3 years of follow-up, she remains in treatment-free remission (TFR).

CONCLUSION

Compared with imatinib, nilotinib achieves earlier and deeper MR that allows safe and timely pregnancies in infertile CML women through IVF process, while patients remain in TFR after delivery.

Regulation of Folliculogenesis by Growth Factors in Piglet Ovary Exposed Prenatally to β-Hydroxy-β-Methylbutyrate (HMB)

Β-hydroxy-β-methylbutyrate (HMB) is one of the leucine metabolites with protein anabolic effects which makes it very popular among athletes. Previously, it was shown that HMB administered during the prenatal period reduced the pool of primordial follicles and increased the proportion of developing follicles in newborn piglets. This work is a further step to understand these morphological alterations. Therefore, the aim of this study was to examine the effect of prenatal HMB treatment on the expression of the Kit ligand, BMP-4, bFGF, and the IGF-1/IGF-1R system which are the main growth factors controlling follicular development. Excised ovaries from 12 newborn piglets, originated from the control (n=6) and HMB-treated (n=6) sows were used for immunohistochemical and western-blot analysis. The tested proteins were localized within egg nests and ovarian follicles. Furthermore, the western-blot assay indicated higher BMP-4, Kit ligand, and IGF-1R expression, while the level of bFGF and IGF-1 proteins decreased after HMB dietary treatment. These findings show that HMB included into sow diet can modulate the expression of growth factors and thereby alter ovarian morphology in offspring. Therefore, this study opens a discussion about the benefits and risks of the diet supplemented with HMB and its potential application in medicine and animal husbandry, and further research is necessary in this area.

Effect of the neuropeptide phoenixin and its receptor GPR173 during folliculogenesis

Folliculogenesis is a complex process, defined by the growth and development of follicles from the primordial population. Granulosa cells (GCs) play a vital role in every stage of follicular growth through proliferation, acquisition of gonadotropic responsiveness, steroidogenesis and production of autocrine/paracrine factors. A recently discovered hypothalamic neuropeptide phoenixin is involved in the regulation of the reproductive system. Phoenixin acts through its receptor, G protein-coupled receptor 173 (GPR173), to activate the cAMP/PKA pathway leading to the phosphorylation of CREB (pCREB). Here, we demonstrated the expression patterns of phoenixin and GPR173 in human ovary and explored its role in folliculogenesis. Phoenixin and GPR173 were both expressed in the human ovarian follicle, with increased expression in GCs as the follicle grows. Phoenixin treatment at 100 nM for 24 h induced the proliferation of human non-luteinized granulosa cell line, HGrC1 and significantly increased the expression levels of CYP19A1, FSHR, LHR and KITL, but decreased NPPC expression levels. These effects were suppressed by GPR173 siRNA. The expression level of CREB1, pCREB and estradiol (E2) production in the culture medium was significantly enhanced by phoenixin treatment in a concentration-dependent manner. Phoenixin also significantly increased the follicular area in a murine ovarian tissue culture model, leading to an increased number of ovulated oocytes with a higher level of maturation. Taken together, our data demonstrate that phoenixin is an intraovarian factor that promotes follicular growth through its receptor GPR173 by accelerating proliferation of GCs, inducing E2 production and increasing the expression of genes related to follicle development.

Long-term imatinib diminishes ovarian reserve and impacts embryo quality

PURPOSE

Tyrosine kinase inhibitors (TKIs) such as imatinib are commonly used chemotherapeutics, but the effects of long-term treatments on reproductive outlook for cancer survivors are unknown. The purpose of this study was to examine the effects of long-term imatinib treatments on follicle development and embryo quality. Since prospective studies are not possible in healthy humans, we have incorporated a commonly used mouse model.

METHODS

Adult female mice were treated with daily IP injections of imatinib for 4-6 weeks. Liquid chromatography-mass spectrometry was used to measure imatinib in serum and ovarian tissues. At the end of treatments, females were superovulated and mated to yield fertilized embryos. Oocytes and embryos were collected from oviducts, assessed for development by microscopy, and fertilized embryos were cultured in vitro. Blastocysts were fixed and stained for differential cell counts.

RESULTS

Long-term imatinib treatments caused a shift in follicle development, with imatinib-treated females having fewer primordial follicles, but an increase in primary and secondary follicles (P < 0.05). There was no effect on ovulation or fertilization rates. However, blastocysts from imatinib-treated females had fewer total cells (P < 0.05) and a significant shift from inner cell mass to increased trophectoderm cells.

CONCLUSION

This pilot study indicates that long-term TKI treatments may have significant impact on ovarian reserve and embryo developmental capacity. More studies are needed in other model systems to determine the long-term impact of TKIs in patients. Knowing the potential effects of chemotherapeutics on reproductive outlook is critical for quality of life and more research is needed.

Prediction of ovarian aging using ovarian expression of BMP15, GDF9, and C-KIT

IMPACT STATEMENT

Ovarian aging is becoming a more important issue in terms of fertility preservation and infertility treatment. Serum anti-Mullerian hormone (AMH) level and antral follicle count (AFC) are being practically used as markers of ovarian aging as well as ovarian reserve in human. However, these factors have some drawbacks in assessing ovarian aging and reserve. Therefore, the identification of ovarian expressions of BMP15, GDF9, and C-KIT according to female could be applied as a potent predictor of ovarian aging. This work provides new information on the development of diagnosis and treatment strategy of age-related fertility decline and premature ovarian insufficiency.

Autophagy in Female Fertility: A Role in Oxidative Stress and Aging

Significance: The precipitous age-related decline in female fertility is intimately associated with a reduction in both the quantity and quality of the germline (oocytes). Although complex etiologies undoubtedly contribute to the deterioration of oocyte quality, increasing attention has focused on the pervasive impact of oxidative stress. Indeed, the prolonged lifespan of the meiotically arrested oocyte places this cell at heightened risk of oxidative lesions, which commonly manifest in dysregulation of protein homeostasis (proteostasis). Although oocytes are able to mitigate this threat via the mobilization of a sophisticated network of surveillance, repair, and proteolytic pathways, these defenses are themselves prone to age-related defects, reducing their capacity to eliminate oxidatively damaged proteins. Recent Advances: Here, we give consideration to the quality control mechanisms identified within the ovary that afford protection to the female germline. Our primary focus is to review recent advances in our understanding of the autophagy pathway and its contribution to promoting oocyte longevity and modulating pathophysiological responses to oxidative stress. In addition, we explore the therapeutic potential of emerging strategies to fortify autophagic activity. Critical Issues: The complex interplay of oxidative stress and autophagy has yet to be fully elucidated within the context of the aging oocyte and surrounding ovarian environment. Future Directions: Emerging evidence provides a strong impetus to resolve the causal link between autophagy and oxidative stress-driven pathologies in the aging oocyte. Such research may ultimately inform novel therapeutic strategies to combat the age-related loss of female fertility via fortification of intrinsic autophagic activity.

Association of Polymorphisms in Candidate Genes with the Litter Size in Two Sheep Breeds

Hu sheep and Small-tailed Han sheep are the most widely raised and most famous maternal sheep breeds in China, which are known for precocious puberty, perennial oestrus and high fecundity (1-6 lambs each parity). Therefore, it is crucial to increase litter size of these two breeds for intensive sheep industry. The objective of this study was to identify potential genetic markers linked with sheep litter size located at ten genes. This study collected blood sample of 537 Hu sheep and 420 Small-tailed Han sheep with litter size of first parity. The average litter sizes in Hu sheep and Small-tailed Han sheep were 2.21 and 1.93. DNA-pooling sequencing method was used for detecting the potential single nucleotide polymorphisms (SNPs) in ten genes related to follicle development and female reproduction. SNPscan® was used for individually genotyping. As a result, a total of 78 putative SNPs in nine out of ten candidate genes (except NOG) were identified. In total, 50 SNPs were successfully genotyped in Hu sheep and Small-tailed Han sheep. After quality control, a total of 42 SNPs in Hu sheep and 44 SNPs in Small-tailed Han sheep were finally used for further analysis. Association analysis revealed that nine SNPs within six genes (KIT: g.70199073A>G, KITLG: g.124520653G>C, ADAMTS1: g.127753565T>C, ADAMTS1: g.127754640G>T, NCOA1: g.31928165C>T, NCOA1: g.32140565G>A, LIFR: g.35862868C>T, LIFR: g.35862947G>T and NGF: g.91795933T>C) were significantly associated with litter size in Hu sheep or Small-tailed Han sheep. A combined haplotypes analysis of the two loci (LIFR: g.35862868C>T and LIFR: g.35862947G>T) revealed that H2H3 (CTTT) combined haplotypes had the largest litter size than the rest combined haplotypes and more than those with either mutation alone in Small-tailed Han sheep. Taken together, our study suggests that nine significant SNPs in six genes can be served as useful genetic markers for MAS in sheep.

Pregnancy Outcomes in Chronic Myeloid Leukemia: A Single Center Experience

PURPOSE

The aim of the current work was to report the effect of imatinib on pregnancy in patients with chronic myeloid leukemia (CML).

METHODS

Data were collected between January 1998 and December 2014. One hundred four patients met inclusion criteria, and we report the results of 104 pregnancies-conceived by the participant or partner-while being on imatinib therapy for CML.

RESULTS

Fifty-eight patients were male and 46 were female. Eighty-three patients, 20 patients, and one patient were had CML in the chronic phase, accelerated phase, or blast phase, respectively. Of 46 female patients, 21 underwent abortion (spontaneous, n = 36.9; elective termination, n = 8.6%). In the case of full-term pregnancy in the female partners of male patients with CML, all outcomes were uneventful. Of 46 female patients, 25 had full-term pregnancy outcomes. During the pre-imatinib era (total n = 6), patients were treated with hydroxyurea, interferon-alpha, and therapeutic leukapheresis. A total 10 of 19 pregnant patients continued on imatinib until their delivery and experienced the following outcomes: normal full-term deliveries (n = 7), preterm delivery (n = 1), omphalocele (n = 1), and craniosynostosis (n = 1). Of those who discontinued imatinib after counseling (n = 9), eight patients had full-term normal delivery, of which two patients required leukapheresis and one patient expired. All patients who continued on imatinib while pregnant were in complete cytogenetic response and major molecular response (MMR) before pregnancy, during pregnancy, and postpregnancy. Of nine patients who discontinued imatinib, two lost MMR during the third trimester and all of these patients were in complete cytogenetic response and MMR before pregnancy.

CONCLUSION

It is clear that there is no standard of care for the best treatment of CML in the case of pregnancy. Interferon and/or leukapheresis will be included as treatment options. Patients can have normal pregnancies even with the administration of imatinib at the risk of congenital anomalies, intervention for which can be done after birth.

Control of Mammalian Oocyte Development by Interactions with the Maternal Follicular Environment

Development of animal germ cells depends critically on continuous contact and communication with the somatic compartment of the gonad. In females, each oocyte is enclosed within a follicle, whose somatic cells supply nutrients that sustain basal metabolic activity of the oocyte and send signals that regulate its differentiation. This maternal microenvironment thus plays an indispensable role in ensuring the production of fully differentiated oocytes that can give rise to healthy embryos. The granulosa cells send signals, likely membrane-associated Kit ligand, which trigger oocytes within resting-stage primordial follicles to initiate growth. During growth, the granulosa cells feed amino acids, nucleotides, and glycolytic substrates to the oocyte. These factors are necessary for the oocyte to complete its growth and are delivered via gap junctions that couple the granulosa cells to the oocyte. In a complementary manner, growing oocytes also release growth factors, notably growth-differentiation factor 9 and bone morphogenetic protein 15, which are necessary for proper differentiation of the granulosa cells and for these cells to support oocyte growth. During the late stages of oocyte growth, cyclic GMP that is synthesized by the granulosa cells and diffuses into the oocyte is required to prevent its precocious entry into meiotic maturation. Finally, at the early stages of maturation, granulosa cell signals promote the synthesis of a subset of proteins within the oocyte that enhance their ability to develop as embryos. Thus, the maternal legacy of the follicular microenvironment is witnessed by the fertilization of the ovulated oocyte and subsequent birth of healthy offspring.

Female Fertility Preservation through Stem Cell-based Ovarian Tissue Reconstitution In Vitro and Ovarian Regeneration In Vivo

Historically, approaches designed to offer women diagnosed with cancer the prospects of having a genetically matched child after completion of their cytotoxic treatments focused on the existing oocyte population as the sole resource available for clinical management of infertility. In this regard, elective oocyte and embryo cryopreservation, as well as autologous ovarian cortical tissue grafting posttreatment, have gained widespread support as options for young girls and reproductive-age women who are faced with cancer to consider. In addition, the use of ovarian protective therapies, including gonadotropin-releasing hormone agonists and sphingosine-1-phosphate analogs, has been put forth as an alternative way to preserve fertility by shielding existing oocytes in the ovaries in vivo from the side-effect damage caused by radiotherapy and many chemotherapeutic regimens. This viewpoint changed with the publication of now numerous reports that adult ovaries of many mammalian species, including humans, contain a rare population of oocyte-producing germ cells-referred to as female germline or oogonial stem cells (OSCs). This new line of study has fueled research into the prospects of generating new oocytes, rather than working with existing oocytes, as a novel approach to sustain or restore fertility in female cancer survivors. Here, we overview the history of work from laboratories around the world focused on improving our understanding of the biology of OSCs and how these cells may be used to reconstitute "artificial" ovarian tissue in vitro or to regenerate damaged ovarian tissue in vivo as future fertility-preservation options.

Imatinib treatments have long-term impact on placentation and embryo survival

Imatinib is an oral chemotherapeutic used primarily to treat chronic myeloid leukemia (CML) and gastrointestinal stromal tumors (GIST). The potential effects of cancer treatments on a patient’s future fertility  are a major concern affecting the quality of life for cancer survivors. The effects of imatinib on future fertility are unknown. It is teratogenic. Therefore, patients are advised to stop treatment before pregnancy. Unfortunately, CML and GIST have high rates of recurrence in the absence of the drug, therefore halting imatinib during pregnancy endangers the mother. Possible long-term (post-treatment) effects of imatinib on reproduction have not been studied. We have used a mouse model to examine the effects of imatinib on the placenta and implantation after long-term imatinib exposure. We found significant changes in epigenetic markers of key imprinted genes in the placenta. There was a significant decrease in the labyrinth zone and vasculature of the placenta, which could impact fetal growth later in pregnancy. These effects on placental growth occurred even when imatinib was stopped prior to pregnancy. These results indicate potential long-term effects of imatinib on pregnancy and implantation. A prolonged wash-out period prior to pregnancy or extra monitoring for possible placental insufficiency may be advisable.

Formation and activation induction of primordial follicles using granulosa and cumulus cells conditioned media

Fertility preservation of prepubertal girls subjected to invasive cancer therapy necessitates defining protocols for activation of isolated primordial follicles. Granulosa (GCs) and cumulus cells (CCs) play pivotal role in oocyte development. Although GCs and CCs share some similarities, they differ in growth factors production. The current study was conducted to evaluate the effects of GCs, CCs and their conditioned media on mice primordial follicles activation. One-day-old mice ovaries were subjected to 6-day culture with base medium (BM), GC conditioned medium (GCCM), GC coculture (GCCC), CC conditioned medium (CCCM) or CC coculture (CCCC). Follicular growth and primordial to primary follicle transition was observed during 6-day culture, and follicular activation rate tended to be greater in GCCM than other groups (0.05 <P < 0.10). On Day 6, the expression of phosphatase and tensin homolog (PTEN) in GCCM group was lower than that in BM group (P = 0.020), the expression of phosphoinositide-3-kinase was higher in CCCC group than BM, GCCM and CCCM groups (P < 0.05), and the expression of connexin 37 was greater in the CCCM group as compared with BM, GCCC, and CCCC groups (P < 0.01). In conclusion, the current study showed that condition medium of GCs could enhance in vitro activation of primordial follicles, probably through downregulation of PTEN.

Expression profiling of c-kit and its impact after esiRNA silencing during gonadal development in catfish

Receptor, c-Kit is a member of a family of growth factor receptors that have tyrosine kinase activity, and are involved in the transduction of growth regulatory signals across plasma membrane by activation of its ligand, kitl/scf. The present study analyzed mRNA and protein expression profiles of c-kit in the gonads of catfish, Clarias gariepinus, using real time PCR, in situ hybridization and immunohistochemistry. Tissue distribution analysis revealed higher expression mainly in the catfish gonads. Ontogeny studies showed minimal expression during early developmental stages and highest during 50-75 days post hatch, and the dimorphic expression in gonads decreased gradually till adulthood, which might suggest an important role for this gene around later stages of sex differentiation and gonadal development. Expression of c-kit was analyzed at various phases of gonadal cycle in both male and female, which showed minimal expression during the resting phase, and higher expression during the pre-spawning phase in male compared to females. In vitro and in vivo induction using human chorionic gonadotropin elevated the expression of c-kit indicating the regulatory influence of hypothalamo-hypophyseal axis. In vivo transient gene silencing using c-kit-esiRNA in adult catfish during gonadal recrudescence showed a decrease in c-kit expression, which affected the expression levels of germ cell meiotic marker sycp3, as well as several factors and steroidogenic enzyme genes that are involved in germ cell development. Decrease in the levels of 11-ketotestosterone and testosterone in serum were also observed after esiRNA silencing. The findings suggests that c-kit has an important role in the process of germ cell proliferation, development and maturation during gonadal development and recrudescence in catfish.

Folliculogenic factors in photoregressed ovaries: Differences in mRNA expression in early compared to late follicle development

The early stages of ovarian folliculogenesis generally progress independent of gonadotropins, whereas later stages require signaling initiated by FSH. In Siberian hamsters, cycles of folliculogenesis are mediated by changes in photoperiod which depress the hypothalamic pituitary gonadal axis. Reduced gonadotropins lead to decreases in mature follicle development and ovulation; however, early stages of folliculogenesis have not been explored in regressed ovaries. We hypothesized that intraovarian factors that contribute predominantly to later stages of folliculogenesis would react to changes in photoperiod, whereas factors contributing to earlier stages would not change. To probe if the early stages of folliculogenesis continue in the photoinhibited ovary while late stages decline, we measured the mRNA abundance of factors that interact with FSH signaling (Fshr, Igf1, Cox2) and factors that can function independently of FSH (c-Kit, Kitl, Foxo3, Figla, Nobox, Sohlh1, Lhx8). While plasma FSH, antral follicles, and corpora lutea numbers declined with exposure to inhibitory photoperiod, the numbers of primordial, primary, and secondary follicles did not change. Expression of factors that interact with FSH signaling changed with changes in photoperiod; however, expression of factors that do not interact with FSH were not significantly altered. These results suggest that the photoinhibited ovary is not completely quiescent, as factors important for follicle selection and early follicle growth are still expressed in regressed ovaries. Instead, the lack of gonadotropin support that characterizes the non-breeding season appears to inhibit only final stages of folliculogenesis in Siberian hamsters.

Copy number variation in livestock: A mini review

Copy number variation (CNV) is a phenomenon in which sections of the genome, ranging from one kilo base pair (Kb) to several million base pairs (Mb), are repeated and the number of repeats vary between the individuals in a population. It is an important source of genetic variation in an individual which is now being utilized rather than single nucleotide polymorphisms (SNPs), as it covers the more genomic region. CNVs alter the gene expression and change the phenotype of an individual due to deletion and duplication of genes in the copy number variation regions (CNVRs). Earlier, researchers extensively utilized SNPs as the main source of genetic variation. But now, the focus is on identification of CNVs associated with complex traits. With the recent advances and reduction in the cost of sequencing, arrays are developed for genotyping which cover the maximum number of SNPs at a time that can be used for detection of CNVRs and underlying quantitative trait loci (QTL) for the complex traits to accelerate genetic improvement. CNV studies are also being carried out to understand the evolutionary mechanism in the domestication of livestock and their adaptation to the different environmental conditions. The main aim of the study is to review the available data on CNV and its role in genetic variation among the livestock.

Regulation of germ cell development by intercellular signaling in the mammalian ovarian follicle

Prior to ovulation, the mammalian oocyte undergoes a process of differentiation within the ovarian follicle that confers on it the ability to give rise to an embryo. Differentiation comprises two phases-growth, during which the oocyte increases more than 100-fold in volume as it accumulates macromolecules and organelles that will sustain early embryogenesis; and meiotic maturation, during which the oocyte executes the first meiotic division and prepares for the second division. Entry of an oocyte into the growth phase appears to be triggered when the adjacent granulosa cells produce specific growth factors. As the oocyte grows, it elaborates a thick extracellular coat termed the zona pellucida. Nonetheless, cytoplasmic extensions of the adjacent granulosa cells, termed transzonal projections (TZPs), enable them to maintain contact-dependent communication with the oocyte. Through gap junctions located where the TZP tips meet the oocyte membrane, they provide the oocyte with products that sustain its metabolic activity and signals that regulate its differentiation. Conversely, the oocyte secretes diffusible growth factors that regulate proliferation and differentiation of the granulosa cells. Gap junction-permeable products of the granulosa cells prevent precocious initiation of meiotic maturation, and the gap junctions also enable oocyte maturation to begin in response to hormonal signals received by the granulosa cells. Development of the oocyte or the somatic compartment may also be regulated by extracellular vesicles newly identified in follicular fluid and at TZP tips, which could mediate intercellular transfer of macromolecules. Oocyte differentiation thus depends on continuous signaling interactions with the somatic cells of the follicle. WIREs Dev Biol 2018, 7:e294. doi: 10.1002/wdev.294 This article is categorized under: Gene Expression and Transcriptional Hierarchies > Cellular Differentiation Signaling Pathways > Cell Fate Signaling Early Embryonic Development > Gametogenesis.

Notch Signaling Regulates Differentiation and Steroidogenesis in Female Mouse Ovarian Granulosa Cells

The Notch pathway is a highly conserved juxtacrine signaling mechanism that is important for many cellular processes during development, including differentiation and proliferation. Although Notch is important during ovarian follicle formation and early development, its functions during the gonadotropin-dependent stages of follicle development are largely unexplored. We observed positive regulation of Notch activity and expression of Notch ligands and receptors following activation of the luteinizing hormone-receptor in prepubertal mouse ovary. JAG1, the most abundantly expressed Notch ligand in mouse ovary, revealed a striking shift in localization from oocytes to somatic cells following hormone stimulation. Using primary cultures of granulosa cells, we investigated the functions of Jag1 using small interfering RNA knockdown. The loss of JAG1 led to suppression of granulosa cell differentiation as marked by reduced expression of enzymes and factors involved in steroid biosynthesis, and in steroid secretion. Jag1 knockdown also resulted in enhanced cell proliferation. These phenotypes were replicated, although less robustly, following knockdown of the obligate canonical Notch transcription factor RBPJ. Intracellular signaling analysis revealed increased activation of the mitogenic phosphatidylinositol 3-kinase/protein kinase B and mitogen-activated protein kinase/extracellular signal-regulated kinase pathways following Notch knockdown, with a mitogen-activated protein kinase kinase inhibitor blocking the enhanced proliferation observed in Jag1 knockdown granulosa cells. Activation of YB-1, a known regulator of granulosa cell differentiation genes, was suppressed by Jag1 knockdown. Overall, this study reveals a role of Notch signaling in promoting the differentiation of preovulatory granulosa cells, adding to the diverse functions of Notch in the mammalian ovary.

Transcriptomic Analysis for Differentially Expressed Genes in Ovarian Follicle Activation in the Zebrafish

In teleosts, the onset of puberty in females is marked by the appearance of the first wave of pre-vitellogenic (PV) follicles from the pool of primary growth (PG) follicles (follicle activation) in the ovary during sexual maturation. To understand the mechanisms underlying follicle activation and therefore puberty onset, we undertook this transcriptomic study to investigate gene expression profiles in the event. Our analysis revealed a total of 2,027 up-regulated and 859 down-regulated genes during the PG-PV transition. Gene Ontology (GO) analysis showed that in addition to basic cellular functions such as gene transcription, cell differentiation, and cell migration, other biological processes such as steroidogenesis, cell signaling and angiogenesis were also enriched in up-regulated genes; by comparison, some processes were down-regulated including piRNA metabolism, gene silencing and proteolysis. Further Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis identified a variety of signaling pathways that might play pivotal roles in PG-PV transition, including MAPK, TGF-β, Hedgehog, FoxO, VEGF, Jak-STAT, and phosphatidylinositol signaling pathways. Other pathways of particular interest included endocytosis and glycosaminoglycan biosynthesis. We also analyzed expression changes of genes expressed in different compartments viz. oocytes and follicle cells. Interestingly, most oocyte-specific genes remained unchanged in expression during follicle activation whereas a great number of genes specifically expressed in the follicle cells showed significant changes in expression. Overall, this study reported a comprehensive analysis for genes, biological processes and pathways involved in follicle activation, which also marks female puberty onset in the zebrafish when occurring for the first time in sexual maturation.

Successful Ovarian Stimulation for Fertility Preservation in a Patient with Chronic Myeloid Leukemia: Switch from Nilotinib to Interferon-α

The development of tyrosine-kinase inhibitors (TKIs) has improved survival of patients with chronic myeloid leukemia (CML). Some patients may become resistant to TKIs and require hematopoietic stem cell transplant (HSCT) that is highly gonadotoxic. Fertility preservation with ovarian stimulation might be indicated but is challenging if patients need to remain on TKIs until HSCT because TKIs may compromise follicular development and response to ovarian stimulation. We report the case of a patient with CML resistant to TKI and planned for an HSCT, in which treatment by TKI was replaced by interferon-α before and during ovarian stimulation for fertility preservation. Successful ovarian stimulation was performed, allowing cryopreservation of nine zygotes. Hematopoietic stem cell transplantation was performed, and at present, 3 years later, the patient presents a sustained major molecular response.

N-Acetylcysteine Compared to Metformin, Improves The Expression Profile of Growth Differentiation Factor-9 and Receptor Tyrosine Kinase c-Kit in The Oocytes of Patients with Polycystic Ovarian Syndrome

Background

Paracrine disruption of growth factors in women with polycystic ovarian syndrome (PCOS) results in production of low quality oocyte, especially following ovulation induction. The aim of this study was to investigate the effects of metformin (MET), N-acetylcysteine (NAC) and their combination on the hormonal levels and expression profile of GDF-9, BMP-15 and c-kit, as hallmarks of oocyte quality, in PCOS patients.

MATERIALS AND METHODS

This prospective randomized, double-blind, placebo controlled trial aims to study the effects of MET, NAC and their combination (MET+NAC) on expression of GDF-9, BMP-15 and c-kit mRNA in oocytes [10 at the germinal vesicle (GV) stage, 10 at the MI stage, and 10 at the MII stage from per group] derived following ovulation induction in PCOS. Treatment was carried out for six weeks, starting on the third day of previous cycle until oocyte aspiration. The expression of GDF9, BMP15 and c-kit were determined by quantitative real time polymerase chain reaction (RT-qPCR) and western blot analysis. Data were analyzed with one-way ANOVA.

RESULTS

The follicular fluid (FF) level of c-kit protein significantly decreased in the NAC group compared to the other groups. Significant correlations were observed between the FF soluble c-kit protein with FF volume, androstenedione and estradiol. The GDF-9 expression in unfertilized mature oocytes were significantly higher in the NAC group compared to the other groups (P<0.001). Similar difference was not observed between the MET, NAC+MET and control groups. The c-kit expression in unfertilized mature oocytes were significantly lower in the NAC group compared to the other groups (P<0.001). Similar difference was not observed between the MET, NAC+MET and control groups (Registration number: IRCT201204159476N1).

CONCLUSION

We concluded that NAC can improve the quality of oocytes in PCOS.

Regulation of androgen receptor signaling by ubiquitination during folliculogenesis and its possible dysregulation in polycystic ovarian syndrome

Although chronic hyperandrogenism suppresses antral follicular development, a phenomenon often observed in polycystic ovarian syndrome (PCOS), whether and how deregulation of androgen receptor (AR) signaling is involved, is not well understood. In the present study, we examined the role of ring finger protein 6 (RNF6) in AR ubiquitination and the possible dysregulation in the expression and actions of growth differentiation factor 9 (GDF9) and kit-ligand (Kitlg) in a chronic androgenized PCOS rat model. 5α-dihydrotestosterone (DHT) treatment in vivo inhibited antral follicle growth, a response mediated through increased RNF6 content, suppressed K63- but increased K48-linked AR ubiquitination as well as the mRNA expression and content of soluble KIT-L (sKitlg) and content of GDF9. These androgenic responses were attenuated by gonadotropin treatment in vivo. Growth of antral follicles from DHT-treated rats in vitro was significantly slower when compared to those of control but was significantly enhanced by exogenous GDF9, suggesting the DHT-induced antral follicular growth arrest is in part the results of GDF9 suppression. Our findings indicate how hyperandrogenism modulates RNF6 content and subsequently AR ubiquitination, resulting in antral follicle growth arrest in a chronically androgenized PCOS rat model.

Molecular evidence that follicle development is accelerated in vitro compared to in vivo

In this study, we systematically compared the morphological, functional and molecular characteristics of granulosa cells and oocytes obtained by a three-dimensional in vitro model of ovine ovarian follicular growth with those of follicles recovered in vivo. Preantral follicles of 200 µm diameter were recovered and cultured up to 950 µm over a 20-day period. Compared with in vivo follicles, the in vitro culture conditions maintained follicle survival, with no difference in the rate of atresia. However, the in vitro conditions induced a slight decrease in oocyte growth rate, delayed antrum formation and increased granulosa cell proliferation rate, accompanied by an increase and decrease in CCND2 and CDKN1A mRNA expression respectively. These changes were associated with advanced granulosa cell differentiation in early antral follicles larger than 400 µm diameter, regardless of the presence or absence of FSH, as indicated by an increase in estradiol secretion, together with decreased AMH secretion and expression, as well as increased expression of GJA1, CYP19A1, ESR1, ESR2, FSHR, INHA, INHBA, INHBB and FST. There was a decrease in the expression of oocyte-specific molecular markers GJA4, KIT, ZP3, WEE2 and BMP15 in vitro compared to that in vivo. Moreover, a higher percentage of the oocytes recovered from cultured follicles 550 to 950 µm in diameter was able to reach the metaphase II meiosis stage. Overall, this in vitro model of ovarian follicle development is characterized by accelerated follicular maturation, associated with improved developmental competence of the oocyte, compared to follicles recovered in vivo.

RNA-binding proteins in human oogenesis: Balancing differentiation and self-renewal in the female fetal germline

Primordial germ cells undergo three significant processes on their path to becoming primary oocytes: the initiation of meiosis, the formation and breakdown of germ cell nests, and the assembly of single oocytes into primordial follicles. However at the onset of meiosis, the germ cell becomes transcriptionally silenced. Consequently translational control of pre-stored mRNAs plays a central role in coordinating gene expression throughout the remainder of oogenesis; RNA binding proteins are key to this regulation. In this review we examine the role of exemplars of such proteins, namely LIN28, DAZL, BOLL and FMRP, and highlight how their roles during germ cell development are critical to oogenesis and the establishment of the primordial follicle pool.

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RNA-binding proteins (RBPs) are key regulators of gene expression during oogenesis.

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RBPs LIN28, DAZL, BOLL and FMRP display stage-specific expression in fetal oocytes.

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LIN28 and DAZL may regulate self-renewal and progression into meiosis respectively.

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BOLL and FMRP may be involved in the later stages of prophase I and oocyte growth.

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RBPs may have critical roles in establishing the ovarian reserve during fetal life.

Ring Finger Protein 6 Mediates Androgen-Induced Granulosa Cell Proliferation and Follicle Growth via Modulation of Androgen Receptor Signaling

The destiny of the ovarian follicle (growth or atresia) is tightly regulated by the actions and interactions of endocrine, paracrine, and autocrine factors. Although androgens are known to be important in the regulation of folliculogenesis, whether they facilitate or suppress follicular growth has been controversial, and the mechanisms involved are not fully understood. Moreover, the role and regulation of androgen receptor (AR) in mediating androgen signaling during follicular development is not clear. Here, we report that the active androgen dihydrotestosterone upregulates the expression of AR and its E3 ligase ring finger protein 6 (RNF6), increasing site-specific AR polyubiquitination and AR transcriptional activity for soluble Kit ligand (sKit-L) expression in preantral follicle growth. RNF6 silencing suppressed dihydrotestosterone-induced AR ubiquitination (lysine residue 63) and proliferation and suppressed apoptosis in preantral granulosa cells, with these responses being overcome by the presence of exogenous sKit-L. Taken together, our findings support the notion that RNF6 plays an important role in androgen-induced, follicle-stage-dependent follicle growth and that it acts by facilitating AR-mediated granulosa cell sKit-L expression and proliferation. Our findings offer insights into the regulatory mechanism of androgen action in ovarian follicular growth.

Expression of kit ligand and insulin-like growth factor binding protein 3 during in vivo or in vitro development of ovarian follicles in sheep

Expression of Kit ligand (KL) and insulin-like growth factor binding protein (IGFBP3) genes was studied at different in vivo and corresponding in vitro stages of development of the ovarian follicles in sheep. The expression of both KL and IGFBP3 was significantly higher in the primordial follicles relative to any other stage of development. Compared to the other stages, the KL expression in the cumulus cells from in vivo grown large antral follicles and that of IGFBP3 in COCs' isolated from large antral follicles matured in vitro for 24 hr were significantly higher. In the oocytes from in vivo grown ovarian follicles, the expression of KL was the same at all the stages of development. Insulin-like growth factor binding protein 3 expression was also the same in the oocytes at all the stages of the development except for a significantly lower expression in those from antral follicles. The expression of KL in the cumulus cells decreased significantly in the in vitro grown early antral follicles but did not change further as the development progressed. The expression of IGFBP3 in the cumulus cells from in vitro grown ovarian follicles appeared to increase as the development progressed although the increase was not significant between any two consecutive stages of development. In the oocytes in in vitro grown ovarian follicles, the expression levels of KL and IGFBP3 genes did not change with development. It is concluded that (i) KL and IGFBP3 genes follow specific patterns of expression during ovarian folliculogenesis and (ii) in vitro culture of preantral follicles compromises the development potential through alterations in the stage-specific patterns of expression of these and other developmentally important genes.

Ovarian Folliculogenesis

The ovary, the female gonad, serves as the source for the germ cells as well as the major supplier of steroid sex hormones. During embryonic development, the primordial germ cells (PGCs) are specified, migrate to the site of the future gonad, and proliferate, forming structures of germ cells nests, which will eventually break down to generate the primordial follicles (PMFs). Each PMF contains an oocyte arrested at the first prophase of meiosis, surrounded by a flattened layer of somatic pre-granulosa cells. Most of the PMFs are kept dormant and only a selected population is activated to join the growing pool of follicles in a process regulated by both intra- and extra-oocyte factors. The PMFs will further develop into secondary pre-antral follicles, a stage which depends on bidirectional communication between the oocyte and the surrounding somatic cells. Many of the signaling molecules involved in this dialog belong to the transforming growth factor β (TGF-β) superfamily. As the follicle continues to develop, a cavity called antrum is formed. The resulting antral follicles relay on the pituitary gonadotropins, follicle-stimulating hormone (FSH), and luteinizing hormone (LH) for their development. Most of the follicles undergo atretic degeneration and only a subset of the antral follicles, known as the dominant follicles, will reach the preovulatory stage at each reproductive cycle, respond to LH, and subsequently ovulate, releasing a fertilizable oocyte. The remaining somatic cells in the raptured follicle will undergo terminal differentiation and form the corpus luteum, which secretes progesterone necessary to maintain pregnancy.

Inside the granulosa transcriptome

The somatic component of follicular structure is a mixture of different cell types, represented by Granulosa cells (GCs) that are the paracrine regulators of the oocyte growth. GCs finely support this process by a continuous bidirectional talk with oocyte, which ensure oocyte quality and competence. Specific pathways are involved in the cross-talk and in both GCs and oocyte development. This review summarizes data from GCs gene expression analysis concerning both their physiological role and their interaction with oocyte. We also explore the CGs transcriptome modifications induced by controlled ovarian stimulation (COS) or pathological conditions and their impact in reproduction. The transcriptome analysis of GCs could be a powerful tool to improve our knowledge about the pathways involved in oocyte development. This approach, associated with new technologies as RNA-seq could allow the identifications of new noninvasive biological markers of oocyte quality to increase the efficiency of clinical IVF. Moreover, GCs expression analysis could be useful to shed light on new therapeutic targets by providing new options for the treatment of infertility.