Age-related expression of TGF beta family receptors in human cumulus oophorus cells

GDF9His209GlnfsTer6/S428T and GDF9Q321X/S428T bi-allelic variants caused female subfertility with defective follicle enlargement

BACKGROUND

Antral follicles consist of an oocyte cumulus complex surrounding by somatic cells, including mural granulosa cells as the inner layer and theca cells as the outsider layer. The communications between oocytes and granulosa cells have been extensively explored in in vitro studies, however, the role of oocyte-derived factor GDF9 on in vivo antral follicle development remains elusive due to lack of an appropriate animal model. Clinically, the phenotype of GDF9 variants needs to be determined.

METHODS

Whole-exome sequencing (WES) was performed on two unrelated infertile women characterized by an early rise of estradiol level and defect in follicle enlargement. Besides, WES data on 1,039 women undergoing ART treatment were collected. A Gdf9Q308X/S415T mouse model was generated based on the variant found in one of the patients.

RESULTS

Two probands with bi-allelic GDF9 variants (GDF9His209GlnfsTer6/S428T, GDF9Q321X/S428T) and eight GDF9S428T heterozygotes with normal ovarian response were identified. In vitro experiments confirmed that these variants caused reduction of GDF9 secretion, and/or alleviation in BMP15 binding. Gdf9Q308X/S415T mouse model was constructed, which recapitulated the phenotypes in probands with abnormal estrogen secretion and defected follicle enlargement. Further experiments in mouse model showed an earlier expression of STAR in small antral follicles and decreased proliferative capacity in large antral follicles. In addition, RNA sequencing of granulosa cells revealed the transcriptomic profiles related to defective follicle enlargement in the Gdf9Q308X/S415T group. One of the downregulated genes, P4HA2 (a collagen related gene), was found to be stimulated by GDF9 protein, which partly explained the phenotype of defective follicle enlargement.

CONCLUSIONS

GDF9 bi-allelic variants contributed to the defect in antral follicle development. Oocyte itself participated in the regulation of follicle development through GDF9 paracrine effect, highlighting the essential role of oocyte-derived factors on ovarian response.

The Contribution of the Sheep and the Goat Model to the Study of Ovarian Ageing

Ovarian ageing stands as the major contributor towards fertility loss. As such, there is an urge for studies addressing the mechanisms that promote ovarian ageing and new strategies aiming to delay it. Recently, the presence of a unique population of multinucleated giant cells has been identified in the ovaries of reproductively aged mice. These cells have been considered hallmarks of ovarian ageing. However, up to date multinucleated giant cells have only been described in the ovaries of the mice. Therefore, the aim of the present work was to evaluate and characterize the presence of such hallmarks of ovarian ageing in the sheep and the goat. In this study, ovaries from juvenile (6 months) and mature animals (18-24 months) were used. The hematoxylin and eosin technique was performed to describe the ovarian morphology and evaluate the ovarian follicle reserve pool. Sudan black B staining and the detection of autofluorescence emission were used to identify and characterize the presence of multinucleated giant cells. Statistical analyses were performed with GraphPad Prism 9.0.0. A decrease in the follicle reserve pool and the presence of multinucleated giant cells, with lipofuscin accumulation and the emission of autofluorescence, were observed in the ovaries of the mature animals of both species. Our results support the interest in the use of the ovine and the caprine model, that share physiological and pathophysiological characteristics with humans, in future studies addressing ovarian ageing.

Age-associated changes in cumulus cells and follicular fluid: the local oocyte microenvironment as a determinant of gamete quality

The ovary is the first organ to age in humans with functional decline evident already in women in their early 30s. Reproductive aging is characterized by a decrease in oocyte quantity and quality, which is associated with an increase in infertility, spontaneous abortions, and birth defects. Reproductive aging also has implications for overall health due to decreased endocrinological output. Understanding the mechanisms underlying reproductive aging has significant societal implications as women globally are delaying childbearing and medical interventions have greatly increased the interval between menopause and total lifespan. Age-related changes inherent to the female gamete are well-characterized and include defects in chromosome and mitochondria structure, function, and regulation. More recently, it has been appreciated that the extra-follicular ovarian environment may have important direct or indirect impacts on the developing gamete, and age-dependent changes include increased fibrosis, inflammation, stiffness, and oxidative damage. The cumulus cells and follicular fluid that directly surround the oocyte during its final growth phase within the antral follicle represent additional critical local microenvironments. Here we systematically review the literature and evaluate the studies that investigated the age-related changes in cumulus cells and follicular fluid. Our findings demonstrate unique genetic, epigenetic, transcriptomic, and proteomic changes with associated metabolomic alterations, redox status imbalance, and increased apoptosis in the local oocyte microenvironment. We propose a model of how these changes interact, which may explain the rapid decline in gamete quality with age. We also review the limitations of published studies and highlight future research frontiers.

Redox imbalance in age-related ovarian dysfunction and perspectives for its prevention

The age at which women have their first child is increasing. This change represents a major health problem to society because advanced maternal age is related with a decay in fertility and an increase in the incidence of a variety of pregnancy complications and offspring health issues. The ovary stands as the main contributor for female reproductive ageing because of the progressive age-related decrease in follicle number and oocyte quality. Loss of redox homeostasis and establishment of an ovarian oxidative microenvironment are seen as major underlying causes for such downfall and impairment of ovarian function. Thus, the use of antioxidants to preserve fertility became an important field of research. In this review, new insights on mechanisms underlying the establishment of oxidative stress and its repercussions on ovarian ageing are addressed, along with the current state of knowledge on antioxidant supplementation and its contribution for healthy ageing and extension of ovarian lifespan.

Cell-free mitochondrial DNA increases granulosa cell apoptosis and reduces aged oocyte blastocyst development in the mouse

Cell-free mitochondrial DNA (cf-mtDNA) released into the extracellular environment can cause cellular inflammatory responses and damage. Here, we investigated the effects of cf-mtDNA on mouse ovarian granulosa cell function and on the developmental competence of oocytes matured in vitro. Granulosa cells in the cf-mtDNA treatment group had a lower ATP content (P < 0.05), a higher apoptotic cell percentage (P < 0.01), and higher mRNA and protein levels of apoptosis-related factors than the control group (P < 0.01). TLR9, NF-кB p65 and MAPK p38 expression levels in granulosa cells were significantly increased in the cf-mtDNA treatment group (P < 0.05). The blastocyst formation rate of aged mice oocytes matured in vitro decreased significantly (P < 0.05) when cf-mtDNA was added to the media, compared with the control. However, the oocytes from young mice were not affected. Our results suggest that cf-mtDNA may impair granulosa cell function and induce granulosa cell apoptosis, subsequently decreasing blastocyst development in aged oocytes. This role of cf-mtDNA may be associated with the binding to TLR9 and the activation of NF-кB p65 and MAPK p38 signaling pathways.

Effects o follicular fluid oxidative status on human mural granulosa cells, oocyte competency and ICSI parameters

PURPOSE

The aim of the present study was to understand the molecular and genetic alterations involved in follicular fluid oxidative process by investigating human mural granulosa cells and to find possible biomarkers for oocyte competency and ICSI outcome measures.

METHODS

A total of 166 patients were included in the study. Total antioxidant and oxidant levels of follicular fluids were measured on the day of oocyte pick-up and oxidative status were calculated. Expression profiles of three potential target proteins in cases of oxidative stress (Hsp70, Tgf-β, Notch1), DNA status and chromatin integrity of mural granulosa cells were analyzed.

RESULTS

TAS levels were positively correlated with the Hsp70 and Tgf-β expression patterns of mural granulosa cells. Mature oocyte rate and fertilization rates were affected negatively by the presence of oxidative stress and a significant positive correlation was found with the oxidative status and the fertilization rate, whereas no correlation with the remaining ICSI parameters in the overall group.

CONCLUSIONS

Oxidative stress detected in follicular fluid adversely affects fertilization rates post-ICSI however no effect on the remaining parameters including embryo quality, pregnancy, and implantation rates. DNA damage, chromatin integrity were increased, whereas Hsp70 and Tgf-ß were decreased in mural granulosa cells in cases of oxidative stress which may indirectly reflect the oocyte competency and may be used as biomarkers for ICSI outcome measures.

Human Cumulus Cells in Long-Term In Vitro Culture Reflect Differential Expression Profile of Genes Responsible for Planned Cell Death and Aging-A Study of New Molecular Markers

In the ovarian follicle, maturation of the oocyte increases in the presence of somatic cells called cumulus cells (CCs). These cells form a direct barrier between the oocyte and external environment. Thanks to bidirectional communication, they have a direct impact on the oocyte, its quality and development potential. Understanding the genetic profile of CCs appears to be important in elucidating the physiology of oocytes. Long-term in vitro culture of CCs collected from patients undergoing controlled ovarian stimulation during in vitro fertilization procedure was conducted. Using microarray expression analysis, transcript levels were assessed on day 1, 7, 15, and 30 of culture. Apoptosis and aging of CCs strictly influence oocyte quality and subsequently the outcome of assisted reproductive technologies (ART). Thus, particular attention was paid to the analysis of genes involved in programmed cell death, aging, and apoptosis. Due to the detailed level of expression analysis of each of the 133 analyzed genes, three groups were selected: first with significantly decreased expression during the culture; second with the statistically lowest increase in expression; and third with the highest significant increase in expression. COL3A1, SFRP4, CTGF, HTR2B, VCAM1, TNFRSF11B genes, belonging to the third group, were identified as potential carriers of information on oocyte quality.

Luteinizing Hormone Action in Human Oocyte Maturation and Quality: Signaling Pathways, Regulation, and Clinical Impact

The ovarian follicle luteinizing hormone (LH) signaling molecules that regulate oocyte meiotic maturation have recently been identified. The LH signal reduces preovulatory follicle cyclic nucleotide levels which releases oocytes from the first meiotic arrest. In the ovarian follicle, the LH signal reduces cyclic nucleotide levels via the CNP/NPR2 system, the EGF/EGF receptor network, and follicle/oocyte gap junctions. In the oocyte, reduced cyclic nucleotide levels activate the maturation promoting factor (MPF). The activated MPF induces chromosome segregation and completion of the first and second meiotic divisions. The purpose of this paper is to present an overview of the current understanding of human LH signaling regulation of oocyte meiotic maturation by identifying and integrating the human studies on this topic. We found 89 human studies in the literature that identified 24 LH follicle/oocyte signaling proteins. These studies show that human oocyte meiotic maturation is regulated by the same proteins that regulate animal oocyte meiotic maturation. We also found that these LH signaling pathway molecules regulate human oocyte quality and subsequent embryo quality. Remarkably, in vitro maturation (IVM) prematuration culture (PMC) protocols that manipulate the LH signaling pathway improve human oocyte quality of cultured human oocytes. This knowledge has improved clinical human IVM efficiency which may become a routine alternative ART for some infertile patients.

Variable DNA methylation of aging-related genes is associated with male COPD

Background

Chronic obstructive pulmonary disease (COPD) is a chronic lung inflammatory disease which has a close relationship with aging. Genome-wide analysis reveals that DNA methylation markers vary obviously with age. DNA methylation variations in peripheral blood have the potential to be biomarkers for COPD. However, the specific DNA methylation of aging-related genes in the peripheral blood of COPD patients remains largely unknown.

Methods

Firstly, 9 aging-related differentially expressed genes (DEGs) in COPD patients were screened out from the 25 aging-related genes profile through a comprehensive screening strategy. Secondly, qPCR and multiple targeted bisulfite enrichment sequencing (MethTarget) were used to detect the mRNA level and DNA methylation level of the 9 differentially expressed genes in the peripheral blood of 60 control subjects and 45 COPD patients. The candidate functional CpG sites were selected on the basis of the regulation ability of the target gene expression. Thirdly, the correlation was evaluated between the DNA methylation level of the key CpG sites and the clinical parameters of COPD patients, including forced expiratory volume in one second (FEV1), forced expiratory volume in one second as percentage of predicted volume (FEV1%), forced expiratory volume/ forced vital capacity (FEV/FVC), modified British medical research council (mMRC) score, acute exacerbation frequency and the situation of frequent of acute aggravation (CAT) score. Lastly, differentially methylated CpG sites unrelated to smoking were also determined in COPD patients.

Results

Of the 9 differentially expressed aging-related genes, the mRNA expression of 8 genes were detected to be significantly down-regulated in COPD group, compared with control group. Meanwhile, the methylated level of all aging-related genes was changed in COPD group containing 219 COPD-related CpG sites in total. Notably, 27 CpG sites of FOXO3 gene showed a lower False Discovery Rate (FDR) and higher methylation difference values. Also, some variable DNA methylation is associated with the severity of COPD. Additionally, of the 219 COPD-related CpG sites, 147 CpG sites were not related to smoking.

Conclusion

These results identified that the mRNA expression and DNA methylation level of aging-related genes were changed in male COPD patients, which provides a molecular link between aging and COPD. The identified CpG markers are associated with the severity of COPD and provide new insights into the prediction and identification of COPD.

Genes responsible for proliferation, differentiation, and junction adhesion are significantly up-regulated in human ovarian granulosa cells during a long-term primary in vitro culture

The human ovarian granulosa cells (GCs) surround the oocyte and form the proper architecture of the ovarian follicle. The ability of GCs to proliferate and differentiate in the conditions of in vitro culture has been proven. However, there is still a large field for extensive investigation of molecular basics, as well as marker genes, responsible for these processes. This study aimed to find the new marker genes, encoding proteins that regulate human GCs in vitro capability for proliferation and differentiation during long-term primary culture. The human follicular GCs were collected from hyper-stimulated ovarian follicles during IVF procedures and transferred to a long-term in vitro culture. The culture lasted for 30 days, with RNA samples isolated at days 1, 7, 15, 30. Transcriptomic analysis was then performed with the use of Affymetrix microarray. Obtained results were then subjected to bioinformatical evaluation and sorting. After subjecting the datasets to KEGG analysis, three differentially expressed ontology groups "cell differentiation" (GO:0030154), "cell proliferation" (GO:0008283) and "cell-cell junction organization" (GO:0045216) were chosen for further investigation. All three of those ontology groups are involved in human GCs' in vitro lifespan, proliferation potential, and survival capability. Changes in expression of genes of interest belonging to the chosen GOs were validated with the use of RT-qPCR. In this manuscript, we suggest that VCL, PARVA, FZD2, NCS1, and COL5A1 may be recognized as new markers of GC in vitro differentiation, while KAT2B may be a new marker of their proliferation. Additionally, SKI, GLI2, FERMT2, and CDH2 could also be involved in GC in vitro proliferation and differentiation processes. We demonstrated that, in long-term in vitro culture, GCs exhibit markers that suggest their ability to differentiate into different cells types. Therefore, the higher expression profile of these genes may also be associated with the induction of cellular differentiation processes that take place beyond the long-term primary in vitro culture.

Micro-RNAs involved in cellular proliferation have altered expression profiles in granulosa of young women with diminished ovarian reserve

PURPOSE

The study aims to determine differences in micro-RNA (miRNA) expression in granulosa (GC) and cumulus cells (CC) between young women with diminished ovarian reserve (DOR) or normal ovarian reserve (NOR). Secondary objective was to identify downstream signaling pathways that could ultimately indicate causes of lower developmental competence of oocytes from young women with DOR.

METHODS

The method of the study is prospective cohort study.

RESULTS

Of the miRNA, 125 are differentially expressed in GC between DOR and NOR. Only nine miRNA were different in CC; therefore, we focused analysis on GC. In DOR GC, miR-100-5p, miR-16-5p, miR-30a-3p, and miR-193a-3p were significantly downregulated, while miR-155-5p, miR-192-5p, miR-128-3p, miR-486-5p, miR130a-3p, miR-92a-3p, miR-17-3p, miR-221-3p, and miR-175p were increased. This pattern predicted higher cell proliferation in the DOR GC. The primary pathways include MAPK, Wnt, and TGFbeta.

CONCLUSIONS

The miRNA pattern identified critical functions in cell proliferation and survival associated with DOR. GC in women with DOR seems to respond differently to the LH surge.