Reduced neurotrophin receptor tropomyosin-related kinase A expression in human granulosa cells: a novel marker of diminishing ovarian reserve

β-NGF Stimulates Steroidogenic Enzyme and VEGFA Gene Expression, and Progesterone Secretion via ERK 1/2 Pathway in Primary Culture of Llama Granulosa Cells

The beta-nerve growth factor (β-NGF) from llama seminal plasma exerts ovulatory and luteotrophic effects following intramuscular or intrauterine infusion in llamas and alpacas. In this study, we investigate the in vitro effect of llama β-NGF on the expression of genes involved in angiogenesis and progesterone synthesis as well as progesterone release in preovulatory llama granulosa cells; we also determine whether these changes are mediated via the ERK1/2 signaling pathway. From adult female llamas, we collected granulosa cells from preovulatory follicles by transvaginal ultrasound-guided follicle aspiration; these cells were pooled and incubated. After 80% confluence, the cultured granulosa cells were treated with β-NGF, β-NGF plus the MAPK inhibitor U0126, or luteinizing hormone, and the abundance of angiogenic and steroidogenic enzyme mRNA transcripts were quantified after 10 and 20 h by RT-qPCR. We also quantified the progesterone concentration in the media after 48 h by radioimmunoassay. We found that application of β-NGF increases the abundance of mRNA transcripts of the vascular endothelial growth factor (VEGFA) and the steroidogenic enzymes cytochrome P450 side-chain cleavage (P450scc/CYP11A1), steroidogenic acute regulatory protein (STAR), and 3β-hydroxysteroid dehydrogenase (HSD3B1) at 10 and 20 h of treatment. Application of the MAPK inhibitor U0126 resulted in downregulation of the genes encoding these enzymes. β-NGF also enhanced progesterone synthesis, which was prevented by the prior application of the MAPK inhibitor U0126. Finally, western blot analysis confirmed that β-NGF activates the ERK1/2 signaling pathway. In conclusion, our results indicate that β-NGF exerts direct luteotropic effects on llama ovarian tissue via the ERK 1/2 pathway.

Transcriptomic and proteomic analyses of ovarian follicles reveal the role of VLDLR in chicken follicle selection

Background

Follicle selection in chickens refers to the process of selecting one follicle from a group of small yellow follicles (SY, 6–8 mm in diameter) for development into 12–15 mm hierarchical follicles (usually F6 follicles), which is an important process affecting laying performance in the poultry industry. Although transcriptomic analysis of chicken ovarian follicles has been reported, integrated analysis of chicken follicles for selection by using both transcriptomic and proteomic approaches is still rarely performed. In this study, we compared the proteomes and transcriptomes of SY and F6 follicles in laying hens and identified several genes involved in chicken follicle selection.

Results

Transcriptomic analysis revealed 855 differentially expressed genes (DEGs) between SY follicles and F6 follicles in laying hens, among which 202 were upregulated and 653 were downregulated. Proteomic analysis revealed 259 differentially expressed proteins (DEPs), including 175 upregulated and 84 downregulated proteins. Among the identified DEGs and DEPs, changes in the expression of seven genes, including VLDLR1, WIF1, NGFR, AMH, BMP15, GDF6 and MMP13, and nine proteins, including VLDLR, VTG1, VTG3, PSCA, APOB, APOV1, F10, ZP2 and ZP3L2, were validated. Further analysis indicated that the mRNA level of chicken VLDLR was higher in F6 follicles than in SY follicles and was also higher in granulosa cells (GCs) than in thecal cells (TCs), and it was stimulated by FSH in GCs.

Conclusions

By comparing the proteomes and transcriptomes of SY and F6 follicles in laying hens, we identified several differentially expressed proteins/genes that might play certain roles in chicken follicle selection. These data may contribute to the identification of functional genes and proteins involved in chicken follicle selection.

Neurotrophins and glial cell line-derived neurotrophic factor in the ovary: physiological and pathophysiological implications

BACKGROUND

Neurotrophins [nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3), and neurotrophin-4 (NT-4)] and glial cell line-derived neurotrophic factor (GDNF) are soluble polypeptide growth factors that are widely recognized for their roles in promoting cell growth, survival and differentiation in several classes of neurons. Outside the nervous system, neurotrophin (NT) and GDNF signaling events have substantial roles in various non-neural tissues, including the ovary.

OBJECTIVE AND RATIONALE

The molecular mechanisms that promote and regulate follicular development and oocyte maturation have been extensively investigated. However, most information has been obtained from animal models. Even though the fundamental process is highly similar across species, the paracrine regulation of ovarian function in humans remains poorly characterized. Therefore, this review aims to summarize the expression and functional roles of NTs and GDNF in human ovarian biology and disorders, and to describe and propose the development of novel strategies for diagnosing, treating and preventing related abnormalities.

SEARCH METHODS

Relevant literature in the English language from 1990 to 2018 describing the role of NTs and GDNF in mammalian ovarian biology and phenotypes was comprehensively selected using PubMed, MEDLINE and Google Scholar.

OUTCOMES

Studies have shown that the neurotrophins NGF, BDNF, NT-3 and NT-4 as well as GDNF and their functional receptors are expressed in the human ovary. Recently, gathered experimental data suggest putative roles for NT and GDNF signaling in the direct control of ovarian function, including follicle assembly, activation of the primordial follicles, follicular growth and development, oocyte maturation, steroidogenesis, ovulation and corpus luteum formation. Additionally, crosstalk occurs between these ovarian regulators and the endocrine signaling system. Dysregulation of the NT system may negatively affect ovarian function, leading to reproductive pathology (decreased ovarian reserve, polycystic ovary syndrome and endometriosis), female infertility and even epithelial ovarian cancers.

WIDER IMPLICATIONS

A comprehensive understanding of the expression, actions and underlying molecular mechanisms of the NT/GDNF system in the human ovary is essential for novel approaches to therapeutic and diagnostic interventions in ovarian diseases and to develop more safe, effective methods of inducing ovulation in ART in the treatment of female infertility.

Pro-nerve growth factor in the ovary and human granulosa cells

BACKGROUND

Pro-nerve growth factor must be cleaved to generate mature NGF, which was suggested to be a factor involved in ovarian physiology and pathology. Extracellular proNGF can induce cell death in many tissues. Whether extracellular proNGF exists in the ovary and may play a role in the death of follicular cells or atresia was unknown.

MATERIALS AND METHODS

Immunohistochemistry of human and rhesus monkey ovarian sections was performed. IVF-derived follicular fluid and human granulosa cells were studied by RT-PCR, qPCR, Western blotting, ATP- and caspase-assays.

RESULTS AND CONCLUSION

Immunohistochemistry of ovarian sections identified proNGF in granulosa cells and Western blotting of human isolated granulosa cells confirmed the presence of proNGF. Ovarian granulosa cells thus produce proNGF. Recombinant human proNGF even at high concentrations did not affect the levels of ATP or the activity of caspase 3/7, indicating that in granulosa cells proNGF does not induce death. In contrast, mature NGF, which was detected previously in follicular fluid, may be a trophic molecule for granulosa cells with unexpected functions. We found that in contrast to proNGF, NGF increased the levels of the transcription factor early growth response 1 and of the enzyme choline acetyl-transferase. A mechanism for the generation of mature NGF from proNGF in the follicular fluid may be extracellular enzymatic cleavage. The enzyme MMP7 is known to cleave proNGF and was identified in follicular fluid and as a product of granulosa cells. Thus the generation of NGF in the ovarian follicle may depend on MMP7.

Bu Shen Tiao Chong recipe restores diminished ovary reserve through the BDNF pathway

PURPOSE

The purpose of this study was to explore the molecular pathway of BSTCR (Bu Shen Tiao Chong recipe) in retrieving diminished ovary reserve (DOR).

METHODS

The DOR model was established through injecting cyclophosphamide and the effect of BSTCR was examined under this background.

RESULTS

BSTCR was shown to restore depleted brain-derived neurotrophic factor (BDNF), CDC2, cyclin B, GSH1, and P38 levels as well as impaired oocyte maturation and the higher apoptosis induced in DOR. BSTCR also enhances the response of oocytes to in vitro fertilization, with higher implantation rate, birth rate, and placenta weight.

CONCLUSION

BSTCR might exert its beneficial role in oocyte maturation and restore DOR through regulating the BDNF pathway. And this pathway itself is probably through the consequence on several serum hormones such as FSH, E2, Inhibin B, etc.

Effects of brain-derived neurotrophic factor on oocyte maturation and embryonic development in a rat model of polycystic ovary syndrome

Brain-derived neurotrophic factor (BDNF) is expressed extensively in the mammalian female reproductive system and has been implicated in the development of follicles and oocytes. However, BDNF expression patterns in the ovary and its effects on oocyte maturation and embryonic development in polycystic ovary syndrome (PCOS) have not been established. In the present study, we established a PCOS model by treating the rats with insulin and human chorionic gonadotropin (hCG). Rats treated with insulin + hCG had heavier bodyweight and ovarian weight, higher circulating concentrations of luteinising hormone (LH) and testosterone (T), and greater homeostatic model assessment of insulin resistance (HOMA-IR) values compared with control rats (P < 0.05). BDNF and its receptor tyrosine kinase type B (TrkB) were located in cyst walls, granulosa and theca cells, and BDNF protein levels were lower in ovaries of insulin + hCG-treated rats (P < 0.05). The rate of oocyte maturation and formation of blastocysts and morulae was greatest in rats treated with 5 ng mL–1 BDNF (P < 0.05) compared to other BDNF groups (1 and 10 ng mL–1) and the control. The control rats were also PCOS rats and were treated without BDNF. There were no significant differences in the rate of germinal vesicle breakdown (GVBD) and fertilisation among the various treatment groups (1, 5 and 10 ng mL–1) and the control group (P > 0.05). The results indicate that in vitro treatment with an appropriate concentration of BDNF not only promotes oocyte maturation, but also rescues embryonic development in rats treated with insulin + hCG as a model of PCOS.

Viability of cumulus cells is associated with basal AMH levels in assisted reproduction

OBJECTIVE(S)

An interesting non-invasive approach to select embryos for transfer is analyzing the health state of somatic granulosa cells surrounding the oocyte addressing their mutual dependence. This prospective study was set up to analyse whether the DNA integrity of cumulus cells correlates with preimplantation development and basal AMH levels.

STUDY DESIGN

Therefore, 56 patients who gave written consent were enrolled. Sequential denudation of the cumulus-oocyte-complexes was performed in order to separate corona radiata from outer cumulus cells. DNA integrity of both cell types was analysed using a modified chromatin dispersion test.

RESULTS

The percentage of viable corona radiata cells per patient showed a linear correlation to blastulation (P<0.05). These innermost cells showed significantly lower rates of strand breaks (P<0.01) as compared to outer cumulus cells. Age-corrected AMH was significantly associated with the DNA integrity of outer cumulus cells (P<0.05).

CONCLUSION(S)

For the first time it could be shown that in fact clinical embryologists deal with two different entities of cumulus cells, inner and outer ones. It seems that any protective mechanism of the female gamete follows an outward gradient, so that negative effects, e.g. apoptosis, may impair outer cumulus cells first. Age-corrected AMH reflects quality of these outer cumulus cells.

KEYWORDS

AMH; Corona radiata cells; DNA fragmentation; Outer cumulus cells; SCD test.