Characterization of FOXO1, 3 and 4 transcription factors in ovaries of fetal, prepubertal and adult rhesus macaques

Chinese herbal medicine alleviates autophagy and apoptosis in ovarian granulosa cells induced by testosterone through PI3K/AKT1/FOXO1 pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Polycystic ovary syndrome (PCOS) is a common gynecological endocrine and metabolic disorder. Chinese herbal medicine has some advantages in the treatment of PCOS with its unique theoretical system and rich clinical practice experiences.

AIM OF THE STUDY

The present study was to investigate the potential mechanisms of Bu-Shen-Jian-Pi Formula (BSJPF) on the treatment of PCOS.

MATERIAL AND METHODS

The combination of ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC/Q-TOF-MS/MS) rapid analysis, network pharmacology, molecular docking analysis and bio-experiments were firstly conducted to identify the main effective components of BSJPF, and to predict the potential mechanisms. The ovarian granulosa cell line (KGN) was treated with testosterone to construct the PCOS model in vitro, and the cells were further treated with the lyophilized powder of BSJPF. The levels of proliferation, autophagy and apoptosis were detected to explore the mechanisms of BSJPF on treating PCOS.

RESULTS

Firstly, thirty-six active compounds were identified in BSJPF and thirty-one potential targets on PCOS were found. Then, PI3K and PDK1 were verified to have good binding activity with the active compounds through molecular docking analysis. In bio-experiments, BSJPF significantly alleviated the arrested proliferation of KGN cells in G0/G1 phase and reduced the active levels of autophagy and apoptosis of KGN cells induced by testosterone. Additionally, the inhibition of autophagy diminished apoptosis, while the repression apoptosis enhanced autophagy. Finally, BSJPF significantly decreased the FOXO1 expression levels induced by testosterone, especially for nuclear FOXO1, and significantly activated the PI3K/AKT pathway.

CONCLUSIONS

BSJPF significantly alleviated the activated autophagy and apoptosis in KGN induced by testosterone through PI3K/AKT1/FOXO1pathway, which is an effective treatment for PCOS.

Dynamic mRNA expression during chicken ovarian follicle development

Ovarian follicle development is a complex and well-orchestrated biological process of great economic significance for poultry production. Specifically, understanding the molecular mechanisms underlying follicular development is essential for high-efficiency follicular development can benefit the entire industry. In addition, domestic egg-laying hens often spontaneously develop ovarian cancer, providing an opportunity to study the genetic, biochemical, and environmental risk factors associated with the development of this cancer. Here, we provide high-quality RNA sequencing data for chicken follicular granulosa cells across 10 developmental stages, which resulted in a total of 204.57 Gb of clean sequencing data (6.82 Gb on average per sample). We also performed gene expression, time-series, and functional enrichment analyses across the 10 developmental stages. Our study revealed that SWF (small while follicle), F1 (F1 hierarchical follicles), and POFs (postovulatory follicles) best represent the transcriptional changes associated with the prehierarchical, preovulatory, and postovulatory stages, respectively. We found that the preovulatory stage F1 showed the greatest divergence in gene expression from the POF stage. Our research lays a foundation for further elucidation of egg-laying performance of chicken and human ovarian disease.

FOXO family isoforms

FOXO family of proteins are transcription factors involved in many physiological and pathological processes including cellular homeostasis, stem cell maintenance, cancer, metabolic, and cardiovascular diseases. Genetic evidence has been accumulating to suggest a prominent role of FOXOs in lifespan regulation in animal systems from hydra, C elegans, Drosophila, and mice. Together with the observation that FOXO3 is the second most replicated gene associated with extreme human longevity suggests that pharmacological targeting of FOXO proteins can be a promising approach to treat cancer and other age-related diseases and extend life and health span. However, due to the broad range of cellular functions of the FOXO family members FOXO1, 3, 4, and 6, isoform-specific targeting of FOXOs might lead to greater benefits and cause fewer side effects. Therefore, a deeper understanding of the common and specific features of these proteins as well as their redundant and specific functions in our cells represents the basis of specific targeting strategies. In this review, we provide an overview of the evolution, structure, function, and disease-relevance of each of the FOXO family members.

A Subpathway and Target Gene Cluster-Based Approach Uncovers lncRNAs Associated with Human Primordial Follicle Activation

Long non-coding RNAs (lncRNAs) are emerging as a critical regulator in controlling the expression level of genes involved in cell differentiation and development. Primordial follicle activation (PFA) is the first step for follicle maturation, and excessive PFA results in premature ovarian insufficiency (POI). However, the correlation between lncRNA and cell differentiation was largely unknown, especially during PFA. In this study, we observed the expression level of lncRNA was more specific than protein-coding genes in both follicles and granulosa cells, suggesting lncRNA might play a crucial role in follicle development. Hence, a systematical framework was needed to infer the functions of lncRNAs during PFA. Additionally, an increasing number of studies indicate that the subpathway is more precise in reflecting biological processes than the entire pathway. Given the complex expression patterns of lncRNA target genes, target genes were further clustered based on their expression similarity and classification performance to reveal the activated/inhibited gene modules, which intuitively illustrated the diversity of lncRNA regulation. Moreover, the knockdown of SBF2-AS1 in the A549 cell line and ZFAS1 in the SK-Hep1 cell line further validated the function of SBF2-AS1 in regulating the Hippo signaling subpathway and ZFAS1 in the cell cycle subpathway. Overall, our findings demonstrated the importance of subpathway analysis in uncovering the functions of lncRNAs during PFA, and paved new avenues for future lncRNA-associated research.

Biomechanical forces and signals operating in the ovary during folliculogenesis and their dysregulation: implications for fertility

BACKGROUND

Folliculogenesis occurs in the highly dynamic environment of the ovary. Follicle cyclic recruitment, neo-angiogenesis, spatial displacement, follicle atresia and ovulation stand out as major events resulting from the interplay between mechanical forces and molecular signals. Morphological and functional changes to the growing follicle and to the surrounding tissue are required to produce oocytes capable of supporting preimplantation development to the blastocyst stage.

OBJECTIVE AND RATIONALE

This review will summarize the ovarian morphological and functional context that contributes to follicle recruitment, growth and ovulation, as well as to the acquisition of oocyte developmental competence. We will describe the changes occurring during folliculogenesis to the ovarian extracellular matrix (ECM) and to the vasculature, their influence on the mechanical properties of the ovarian tissue, and, in turn, their influence on the regulation of signal transduction. Also, we will outline how their dysregulation might be associated with pathologies such as polycystic ovary syndrome (PCOS), endometriosis or premature ovarian insufficiency (POI). Finally, for each of these three pathologies, we will highlight therapeutic strategies attempting to correct the altered biomechanical context in order to restore fertility.

SEARCH METHODS

For each area discussed, a systematic bibliographical search was performed, without temporal limits, using PubMed Central, Web of Science and Scopus search engines employing the keywords extracellular matrix, mechanobiology, biomechanics, vasculature, angiogenesis or signalling pathway in combination with: ovary, oogenesis, oocyte, folliculogenesis, ovarian follicle, theca, granulosa, cumulus, follicular fluid, corpus luteum, meiosis, oocyte developmental competence, preimplantation, polycystic ovary syndrome, premature ovarian insufficiency or endometriosis.

OUTCOMES

Through search engines queries, we yielded a total of 37 368 papers that were further selected based on our focus on mammals and, specifically, on rodents, bovine, equine, ovine, primates and human, and also were trimmed around each specific topic of the review. After the elimination of duplicates, this selection process resulted in 628 papers, of which 287 were cited in the manuscript. Among these, 89.2% were published in the past 22 years, while the remaining 8.0%, 2.4% or 0.3% were published during the 1990s, 1980s or before, respectively. During folliculogenesis, changes occur to the ovarian ECM composition and organization that, together with vasculature modelling around the growing follicle, are aimed to sustain its recruitment and growth, and the maturation of the enclosed oocyte. These events define the scenario in which mechanical forces are key to the regulation of cascades of molecular signals. Alterations to this context determine impaired folliculogenesis and decreased oocyte developmental potential, as observed in pathological conditions which are causes of infertility, such as PCOS, endometriosis or POI.

WIDER IMPLICATIONS

The knowledge of these mechanisms and the rules that govern them lay a sound basis to explain how follicles recruitment and growth are modulated, and stimulate insights to develop, in clinical practice, strategies to improve follicular recruitment and oocyte competence, particularly for pathologies like PCOS, endometriosis and POI.

Aberrant activation of KRAS in mouse theca-interstitial cells results in female infertility

KRAS plays critical roles in regulating a range of normal cellular events as well as pathological processes in many tissues mediated through a variety of signaling pathways, including ERK1/2 and AKT signaling, in a cell-, context- and development-dependent manner. The in vivo function of KRAS and its downstream targets in gonadal steroidogenic cells for the development and homeostasis of reproductive functions remain to be determined. To understand the functions of KRAS signaling in gonadal theca and interstitial cells, we generated a Kras mutant (tKrasMT) mouse line that selectively expressed a constitutively active KrasG12D in these cells. KrasG12D expression in ovarian theca cells did not block follicle development to the preovulatory stage. However, tKrasMT females failed to ovulate and thus were infertile. The phosphorylated ERK1/2 and forkhead box O1 (FOXO1) and total FOXO1 protein levels were markedly reduced in tKrasMT theca cells. KrasG12D expression in theca cells also curtailed the phosphorylation of ERK1/2 and altered the expression of several ovulation-related genes in gonadotropin-primed granulosa cells. To uncover downstream targets of KRAS/FOXO1 signaling in theca cells, we found that the expression of bone morphogenic protein 7 (Bmp7), a theca-specific factor involved in ovulation, was significantly elevated in tKrasMT theca cells. Chromosome immunoprecipitation assays demonstrated that FOXO1 interacted with the Bmp7 promoter containing forkhead response elements and that the binding activity was attenuated in tKrasMT theca cells. Moreover, Foxo1 knockdown caused an elevation, whereas Foxo1 overexpression resulted in an inhibition of Bmp7 expression, suggesting that KRAS signaling regulates FOXO1 protein levels to control Bmp7 expression in theca cells. Thus, the anovulation phenotype observed in tKrasMT mice may be attributed to aberrant KRAS/FOXO1/BMP7 signaling in theca cells. Our work provides the first in vivo evidence that maintaining normal KRAS activity in ovarian theca cells is crucial for ovulation and female fertility.

The Role of Noncoding RNA in the Pathophysiology and Treatment of Premature Ovarian Insufficiency

Premature ovarian insufficiency (POI) is defined as a loss of ovarian function before the age of 40 years, with a prevalence rate estimated at approximately 1%. It causes infertility and is related to serious long-term health consequences, including reduced life expectancy, increased cardiovascular risk, decreased bone mineral density and neurological disorders. There is currently no effective therapy for POI that is widely available in clinical practice; therefore, the treatment of patients with POI is based on hormone replacement therapy. One of the recent advances in the understanding of the pathophysiology of POI has been the role of microRNAs (miRNAs) and other noncoding RNAs (ncRNAs) in the disease. Moreover, intensive research on human folliculogenesis and reproductive biology has led to the development of novel promising therapeutic strategies with the use of exosomal miRNAs derived from mesenchymal stem cells to restore ovarian function in POI patients. This narrative review focuses on the new studies concerning the role of ncRNAs in the pathogenesis of POI, together with their potential as biomarkers of the disease and targets for therapy.

A kaleidoscopic view of ovarian genes associated with premature ovarian insufficiency and senescence

Ovarian infertility and subfertility presenting with premature ovarian insufficiency (POI) and diminished ovarian reserve are major issues facing the developed world due to the trend of delaying childbirth. Ovarian senescence and POI represent a continuum of physiological/pathophysiological changes in ovarian follicle functions. Based on advances in whole exome sequencing, evaluation of gene copy variants, together with family-based and genome-wide association studies, we discussed genes responsible for POI and ovarian senescence. We used a gene-centric approach to sort out literature deposited in the Ovarian Kaleidoscope database (http://okdb.appliedbioinfo.net) by sub-categorizing candidate genes as ligand-receptor signaling, meiosis and DNA repair, transcriptional factors, RNA metabolism, enzymes, and others. We discussed individual gene mutations found in POI patients and verification of gene functions in gene-deleted model organisms. Decreased expression of some of the POI genes could be responsible for ovarian senescence, especially those essential for DNA repair, meiosis and mitochondrial functions. We propose to set up a candidate gene panel for targeted sequencing in POI patients together with studies on mitochondria-associated genes in middle-aged subfertile patients.

MicroRNA 195-5p Targets Foxo3 Promoter Region to Regulate Its Expression in Granulosa Cells

Forkhead box O3 (Foxo3) is a member of the FOXO subfamily within the forkhead box (FOX) family, which has been shown to be essential for ovarian follicular development and maturation. Previous studies have shown the abundant expression of miR-195-5p in the nuclei of porcine granulosa cells (GCs), suggesting its potential role during ovarian follicle growth. In this study, a conditional immortalized porcine granulosa cell (CIPGC) line was used to determine whether the expression of Foxo3 could be regulated by the nuclear-enriched miR-195-5p. Through silico target prediction, we identified a potential binding site of miR-195-5p within the Foxo3 promoter. The over-expression of miR-195-5p increased Foxo3 expression at both mRNA and protein levels, while the knockdown of miR-195-5p decreased the expression of Foxo3. Furthermore, driven by the Foxo3 promoter, luciferase reporter activity was increased in response to miR-195-5p, while the mutation of the miR-195-5p binding site in the promoter region abolished this effect. In addition, the siRNA knockdown of Argonaute (AGO) 2, but not AGO1, significantly decreased Foxo3 transcript level. However, miR-195-5p failed to upregulate Foxo3 expression when AGO2 was knocked down. Moreover, chromatin immunoprecipitation (CHIP) assay showed that anti-AGO2 antibody pulled down both AGO2 and the Foxo3 promoter sequence, suggesting that AGO2 may be required for miR-195-5p to regulate Foxo3 expression in the nucleus. Additionally, Foxo3 expression was significantly increased by valproic acid (VPA), the inhibitor of deacetylase, as well as by methyltransferase inhibitor BIX-01294, indicating the involvement of histone modification. These effects were further enhanced in the presence of miR-195-5p and were decreased when miR-195-5p was knocked down. Overall, our results suggest that nuclear-enriched miR-195-5p regulates Foxo3 expression, which may be associated with AGO2 recruitment, as well as histone demethylation and acetylation in ovarian granulosa cells.

Alpha Lipoic Acid Supplementation Improves Ovarian Tissue Vitrification Outcome: An Alternative to Preserve the Ovarian Function of Morada Nova Ewe

This study evaluated the effect of adding alpha lipoic acid (ALA) to the vitrification solution of sheep ovarian tissue on 7 days of in vitro culture or 15 days of xenotransplantion. ALA was used at two different concentrations (100 μM: ALA100 and 150 μM: ALA150). Ovarian tissue was evaluated by classical histology (follicular morphology, development, and stromal cell density); immunohistochemistry for forkhead box O3a (FOXO3a); Ki67 (cell proliferation); cluster of differentiation 31 (CD31); and alpha smooth muscle actin (α-SMA). Reactive oxygen species (ROS) levels in ovarian tissue, as well as malondialdehyde (MDA) and nitrite levels in the culture medium, were assessed. Similar percentage of morphologically normal follicles was found in the vitrified ovarian tissue in the presence of ALA100 or ALA150 after in vitro culture or xenotransplantation. Follicular development from all treatments was higher (P < 0.05) than the control group. Moreover, an activation of primordial follicles was observed by FOXO3a. Stromal cell density and immunostaining for Ki67 and CD31 were significantly higher (P < 0.05) in ALA150 vitrified tissue. No difference (P > 0.05) was found in α-SMA between ALA concentrations after in vitro culture or xenograft. ROS levels in the ovarian tissue were similar (P > 0.05) in all treatments, as well as MDA and nitrite levels after 7 days of culture. We concluded that the addition of ALA 150 is able to better preserve the stromal cell density favoring granulosa cell proliferation and neovascularization.

Fertility preservation in women with ovarian cancer: Finding new pathways: A case-control study

Background

Surgery and chemotherapy are the two most common treatments for cancers, including ovarian cancer. Although most ovarian cancers occur over the age of 45 yr, it may involve younger women and affect their reproductive ability.

Objective

To assess the expression of Leucine-rich repeat-containing G-protein coupled receptor 5 (LGR5), Forkhead Box O1 (FOXO1), and miR-340 genes in the ovarian cancer tissues as well as ovarian cancer cell lines.

Materials and Methods

In this case-control study, 30 ovarian cancer samples (with the average age of 37 ± 2.5 years) coupled with their non-tumor marginal tissue (as a control) were collected. Proliferated cell lines were treated with several concentrations of cisplatin, and the half maximal inhibitory concentration (IC50) of cisplatin was quantified by MTT-assay. After RNA extraction, cDNA synthesis and qRT-PCR were done. Finally, the results were analyzed.

Results

While the expression levels of miR-340 and FOXO1 genes in tumor samples displayed a significant reduction (p ≤ 0.001), the LGR5 gene presented a significant increase in expression (p ≤ 0.0001). However, conversely, the expression levels of miR-340 and FOXO1 genes in cisplatin-sensitive cell lines, after 24, 48, and 72 hr of cisplatin treatment, indicated a significant increase (p ≤ 0.001) while the expression of LGR5 gene showed a significant decrease in the cisplatin-sensitive cell line (p < 0.05).

Conclusion

The LGR5, FOXO1, and miR-340 genes can be targeted for early diagnosis and more accurate treatment of ovarian cancer and may prevent some of the ovarian cancer complications such as infertility.

PTEN and FOXO3 expression in the prenatal and postnatal human ovary

PURPOSE

The objective of this study was to analyse the expression and cellular localization of FOXO3, pFOXO3 and PTEN throughout human ovary development both before and after birth.

METHODS

Foetal, pubertal and adult paraffin-embedded ovarian samples were analysed by immunohistochemistry for cellular localization of FOXO3, pFOXO3 and PTEN proteins. Protein and mRNA expression were analysed by western blot and real time PCR, respectively, from fresh biopsies.

RESULTS

PTEN was not detected by immunohistochemistry in germ cells and follicles of foetal, pubertal and adult ovaries. Occasional PTEN immunoreactive granulosa cells were found in atretic antral follicles in the adult ovary. Western blot analysis showed low levels of PTEN protein. Nuclear FOXO3-expressing primordial follicles represented a variable proportion of the ovarian reserve. The presence of FOXO3-expressing primordial follicles was very low in foetal ovary; although always represented in a low proportion, prevalence increased during pubertal and adult life.

CONCLUSION

Our results seem to indicate that two subpopulations of primordial follicles, i.e. nuclear FOXO3-expressing and no FOXO3-expressing primordial follicles are found in the postnatal human ovary. This scenario suggests that FOXO3 could be acting as in the mouse model, preventing primordial follicle activation. However, the strategy would not be an "all or nothing" system as in mouse ovary but rather a selected subpopulation of primordial follicles preserved to ensure long-term fertility.

Demographic and evolutionary trends in ovarian function and aging

BACKGROUND

The human female reproductive lifespan is regulated by the dynamics of ovarian function, which in turn is influenced by several factors: from the basic molecular biological mechanisms governing folliculogenesis, to environmental and lifestyle factors affecting the ovarian reserve between conception and menopause. From a broader point of view, global and regional demographic trends play an additional important role in shaping the female reproductive lifespan, and finally, influences on an evolutionary scale have led to the reproductive senescence that precedes somatic senescence in humans.

OBJECTIVE AND RATIONALE

The narrative review covers reproductive medicine, by integrating the molecular mechanisms of ovarian function and aging with short-term demographic and long-term evolutionary trends.

SEARCH METHODS

PubMed and Google Scholar searches were performed with relevant keywords (menopause, folliculogenesis, reproductive aging, reproductive lifespan and life history theory). The reviewed articles and their references were restricted to those written in English.

OUTCOMES

We discuss and summarize the rapidly accumulating information from large-scale population-based and single-reproductive-cell genomic studies, their constraints and advantages in the context of female reproductive aging as well as their possible evolutionary significance on the life history trajectory from foetal-stage folliculogenesis until cessation of ovarian function in menopause. The relevant environmental and lifestyle factors and demographic trends are also discussed in the framework of predominant evolutionary hypotheses explaining the origin and maintenance of menopause.

WIDER IMPLICATIONS

The high speed at which new data are generated has so far raised more questions than it has provided solid answers and has been paralleled by a lack of satisfactory interpretations of the findings in the context of human life history theory. Therefore, the recent flood of data could offer an unprecedented tool for future research to possibly confirm or rewrite human evolutionary reproductive history, at the same time providing novel grounds for patient counselling and family planning strategies.

Role of the PI3K and Hippo pathways in follicle activation after grafting of human ovarian tissue

PURPOSE

Our aim was to elucidate the mechanisms involved in follicle activation of the ovarian reserve after human ovarian tissue transplantation, with specific focus on the role of the effectors of the PI3K (mTOR and FOXO1) and Hippo (YAP) signaling pathways and whether they are somehow altered.

METHODS

Frozen-thawed ovarian tissue was collected from six women (age 25-35 years) undergoing surgery for non-ovarian pathologies and divided into 4 fragments in each case: one for non-grafted controls and three for grafting to immunodeficient mice for 3, 7 and 21 days. The tissue was processed for hematoxylin and eosin staining, immunohistochemistry and immunofluorescence at different timepoints before and after grafting. Activation of the PI3K and Hippo signaling pathways was investigated by analysis of mTOR phosphorylation, FOXO1 cytoplasmic localization and YAP nuclear localization.

RESULTS

No change in mTOR levels was observed in primordial follicles post-transplantation, but a significant upturn was recorded in growing follicles compared with primordial follicles, irrespective of grafting time. A higher percentage of primordial follicles was also found with FOXO1 in the cytoplasm after 3 days of transplantation than in non-grafted controls. Finally, a greater proportion of primordial follicles was detected with YAP in the nucleus at all timepoints after grafting.

CONCLUSIONS

This study supports the hypothesis that follicle activation may occur as an early event after transplantation, with follicle growth and death both contributing to the burnout phenomenon. This is the first time that the effectors of the PI3K and Hippo pathways have been investigated in grafted human ovarian tissue and their role in burnout documented.

Identification and expression of forkhead box genes in the Chinese giant salamander Andrias davidianus

In the present study, 21 forkhead box (Fox) genes were identified in Andrias davidianus, including 13 full-length genes and eight partial sequences. Phylogenetic analysis showed that most were conserved in other investigated amphibians, whereas the Foxk1 gene was found exclusively in A. davidianus. Molecular evolution analysis indicated that most Fox genes underwent purifying selection, whereas two sites of the adFoxp4 gene showed positive selection and were located on the adFoxp4 protein surface. Expression profiles of all Fox genes identified were analysed in the hypothalamic-pituitary-gonad axis by reverse transcription-quantitative polymerase chain reaction. Eighteen genes exhibited sexually dimorphic expression (15 ovary-biased and three testis-biased genes), whereas two genes showed no difference between ovary and testis. Further investigation of 12 selected sexually dimorphic Fox genes showed changes in the expression profile of 11 genes in the ovary of larvae reared at high temperatures (28°C). The results of the present study provide information on Fox genes in an amphibian and suggest that they play key roles in sexual development and reproduction in A. davidianus.

FOXO3a is essential for murine endometrial decidualization through cell apoptosis during early pregnancy

Embryo implantation is essential for normal pregnancy, and the process of decidualization is critical for embryo implantation. However, the mechanism of decidualization during early pregnancy is still unknown. Forkhead box O3a (FOXO3a) is the most important functional transcription factor of the forkhead box family and is a highly conserved transcription factor of apoptosis-related genes. In the mouse uterus, FOXO3a was found to be expressed regularly from Days 1-7 of early pregnancy. Upon further exploration, it was found that FOXO3a was expressed at significantly higher levels at the implantation site than at the interimplantation site on Days 5-7 of pregnancy. Under artificial decidualization, FOXO3a was highly expressed in the first and second decidual zones. After decidualization, the expression of FOXO3a was significantly increased both in vivo and vitro. In primary stromal cells, apoptosis was reduced by decreased expression of FOXO3a after inducing decidualization. Moreover, when FOXO3a-small interfering RNA was transfected into the uteri of mice, the expression of decidualization- and apoptosis-related factors was impaired. Thus, FOXO3a might play an important role in decidualization during early pregnancy, and cell apoptosis might be one of pathways for FOXO3a-regulated decidualization.