Role of Granulosa Cells in the Aging Ovarian Landscape: A Focus on Mitochondrial and Metabolic Function

Long non-coding ribonucleic acid SNHG18 induced human granulosa cell apoptosis via disruption of glycolysis in ovarian aging

BACKGROUND

In-depth understanding of dynamic expression profiles of human granulosa cells (GCs) during follicular development will contribute to the diagnostic and targeted interventions for female infertility. However, genome-scale analysis of long non-coding ribonucleic acid (lncRNA) in GCs across diverse developmental stages is challenging. Meanwhile, further research is needed to determine how aberrant lncRNA expression participates in ovarian diseases.

METHODS

Granulosa cell-related lncRNAs data spanning five follicular development stages were retrieved and filtered from the NCBI dataset (GSE107746). Stage-specific lncRNA expression patterns and mRNA-lncRNA co-expression networks were identified with bioinformatic approaches. Subsequently, the expression pattern of SNHG18 was detected in GCs during ovarian aging. And SNHG18 siRNA or overexpression plasmids were transfected to SVOG cells in examining the regulatory roles of SNHG18 in GC proliferation and apoptosis. Moreover, whether PKCɛ/SNHG18 signaling take part in GC glycolysis via ENO1 were verified in SVOG cells.

RESULTS

We demonstrated that GC-related lncRNAs were specifically expressed across different developmental stages, and coordinated crucial biological functions like mitotic cell cycle and metabolic processes in the folliculogenesis. Thereafter, we noticed a strong correlation of PRKCE and SNHG18 expression in our analysis. With downregulated SNHG18 of GCs identified in the context of ovarian aging, SNHG18 knockdown could further induce cell apoptosis, retard cell proliferation and exacerbate DNA damage in SVOG cell. Moreover, downregulated PKCɛ/SNHG18 pathway interrupted the SVOG cell glycolysis by lowering the ENO1 expression.

CONCLUSIONS

Altogether, our results revealed that folliculogenesis-related lncRNA SNHG18 participated in the pathogenesis of ovarian aging, which may provide novel biomarkers for ovarian function and new insights for the infertility treatment.

Targeting Cell Senescence and Senolytics: Novel Interventions for Age-Related Endocrine Dysfunction

Multiple changes occur in hormonal regulation with aging and across various endocrine organs. These changes are associated with multiple age-related disorders and diseases. A better understanding of responsible underling biological mechanisms could help in the management of multiple endocrine disorders over and above hormone replacement therapy (HRT). Cellular senescence is involved in multiple biological aging processes and pathologies common in elderly individuals. Cellular senescence, which occurs in many older individuals but also across the lifespan in association with tissue damage, acute and chronic diseases, certain drugs, and genetic syndromes, may contribute to such endocrine disorders as osteoporosis, metabolic syndrome, and type 2 diabetes mellitus. Drugs that selectively induce senescent cell removal, "senolytics,", and drugs that attenuate the tissue-destructive secretory state of certain senescent cells, "senomorphics," appear to delay the onset of or alleviate multiple diseases, including but not limited to endocrine disorders such as diabetes, complications of obesity, age-related osteoporosis, and cancers as well as atherosclerosis, chronic kidney disease, neurodegenerative disorders, and many others. More than 30 clinical trials of senolytic and senomorphic agents have already been completed, are underway, or are planned for a variety of indications. Targeting senescent cells is a novel strategy that is distinct from conventional therapies such as HRT, and thus might address unmet medical needs and can potentially amplify effects of established endocrine drug regimens, perhaps allowing for dose decreases and reducing side effects.

Reproductive Ageing: Metabolic contribution to age-related chromosome missegregation in mammalian oocytes

In brief

Chromosome missegregation and declining energy metabolism are considered to be unrelated features of oocyte ageing that contribute to poor reproductive outcomes. Given the bioenergetic cost of chromosome segregation, we propose here that altered energy metabolism during ageing may be an underlying cause of age-related chromosome missegregation and aneuploidy.

Abstract

Advanced reproductive age in women is a major cause of infertility, miscarriage and congenital abnormalities. This is principally caused by a decrease in oocyte quality and developmental competence with age. Oocyte ageing is characterised by an increase in chromosome missegregation and aneuploidy. However, the underlying mechanisms of age-related aneuploidy have not been fully elucidated and are still under active investigation. In addition to chromosome missegregation, oocyte ageing is also accompanied by metabolic dysfunction. In this review, we integrate old and new perspectives on oocyte ageing, chromosome segregation and metabolism in mammalian oocytes and make direct links between these processes. We consider age-related alterations to chromosome segregation machinery, including the loss of cohesion, microtubule stability and the integrity of the spindle assembly checkpoint. We focus on how metabolic dysfunction in the ageing oocyte disrupts chromosome segregation machinery to contribute to and exacerbate age-related aneuploidy. More specifically, we discuss how mitochondrial function, ATP production and the generation of free radicals are altered during ageing. We also explore recent developments in oocyte metabolic ageing, including altered redox reactions (NAD+ metabolism) and the interactions between oocytes and their somatic nurse cells. Throughout the review, we integrate the mechanisms by which changes in oocyte metabolism influence age-related chromosome missegregation.

Enhancing Oocyte Quality in Aging Mice: Insights from Mesenchymal Stem Cell Therapy and FOXO3a Signaling Pathway Activation

Ovarian aging reduced the quality of oocytes, resulting in age-related female infertility. It is reported that mesenchymal stem cells (MSCs) therapy can improve age-related ovarian function decline and the success rate of in vitro maturation (IVM) in assisted reproductive therapy. In order to investigate the effectiveness and mechanisms of MSCs to enhance oocyte quality of cumulus oocyte complexes (COCs) in advanced age, this study focus on the respective functional improvement of oocytes and granulosa cells (GCs) from aging mice and further to explore and verify the possible mechanisms. Here, we studied a popular but significant protein of follicular development, Forkhead box O-3a (FOXO3a), which is a transcription factor that mediates a variety of cellular processes, but the functions of which in regulating oocyte quality in MSCs therapy still remain inconclusive. In this study, the RNA-seq data of metaphase II (MII) oocytes and GCs isolated from COCs confirmed that, GCs of immature follicles show the most potential to be the targeted cells of bone marrow mesenchymal stem cells (BMSCs) by FOXO3a signaling pathway. Furthermore, we demonstrated the effectiveness of BMSCs co-culture with aging COCs to enhance oocyte quality and found its mechanism to function via ameliorating the biological function of GCs by alleviating FOXO3a levels. These results provide significant fundamental research on MSCs therapy on ovarian aging, as well as offering guidance for raising the success rate of assisted reproductive technology such IVM in clinical and non-clinical settings.

Osteoporosis induced by cellular senescence: A mathematical model

Osteoporosis is a disease characterized by loss of bone mass, where bones become fragile and more likely to fracture. Bone density begins to decrease at age 50, and a state of osteoporosis is defined by loss of more than 25%. Cellular senescence is a permanent arrest of normal cell cycle, while maintaining cell viability. The number of senescent cells increase with age. Since osteoporosis is an aging disease, it is natural to consider the question to what extend senescent cells induce bone density loss and osteoporosis. In this paper we use a mathematical model to address this question. We determine the percent of bone loss for men and women during age 50 to 100 years, and the results depend on the rate η of net formation of senescent cell, with η = 1 being the average rate. In the case η = 1, the model simulations are in agreement with empirical data. We also consider senolytic drugs, like fisetin and quercetin, that selectively eliminate senescent cells, and assess their efficacy in terms of reducing bone loss. For example, at η = 1, with estrogen hormonal therapy and early treatment with fisetin, bone density loss for women by age 75 is 23.4% (below osteoporosis), while with no treatment with fisetin it is 25.8% (osteoporosis); without even a treatment with estrogen hormonal therapy, bone loss of 25.3% occurs already at age 65.

Intravascular Laser Blood Irradiation (ILIB) Enhances Antioxidant Activity and Energy Metabolism in Aging Ovaries

BACKGROUND

Ovarian aging is characterized by the accumulation of free radicals, leading to tissue damage and affecting reproductive health. Intravascular laser irradiation of blood (ILIB, using a low-energy He-Ne laser) is known for its efficacy in treating vascular-related diseases by reducing free radicals and inflammation. However, its impact on ovarian aging remains unexplored. This study aimed to investigate the effects of ILIB on oxidative stress and energy metabolism in aging ovaries.

METHODS

Genetic analysis was conducted on 75 infertile patients with aging ovaries, divided into ILIB-treated and control (CTRL) groups. Patients underwent two courses of laser treatment, and clinical parameters were evaluated. Cumulus cells were collected for the genetic analysis of oxeiptosis, glycolysis, and the tricarboxylic acid (TCA) cycle.

RESULTS

The analysis of gene expression patterns revealed intriguing findings in ILIB-treated patients compared to the untreated group. Notably, ILIB treatment resulted in significant upregulation of oxeiptosis-related genes AIFM1 and NRF2, suggesting a potential protective effect against oxidative stress-induced cell death. Furthermore, ILIB treatment led to a downregulation of glycolysis-associated gene hexokinase 2 (HK2), indicating a shift away from anaerobic metabolism, along with an increase in PDHA levels, indicative of enhanced mitochondrial function. Consistent with these changes, ILIB-treated patients exhibited elevated expression of the key TCA cycle genes citrate synthase (CS), succinate dehydrogenase complex subunit A (SDHA), and fumarate hydratase (FH), signifying improved energy metabolism.

CONCLUSION

The findings from this study underscore the potential of ILIB as a therapeutic strategy for mitigating ovarian aging. By targeting oxidative stress and enhancing energy metabolism, ILIB holds promise for preserving ovarian function and reproductive health in aging individuals. Further research is warranted to elucidate the underlying mechanisms and optimize the application of ILIB in clinical settings, with the ultimate goal of improving fertility outcomes in women experiencing age-related ovarian decline.

Cellular atlas of the human ovary using morphologically guided spatial transcriptomics and single-cell sequencing

The reproductive and endocrine functions of the ovary involve spatially defined interactions among specialized cell populations. Despite the ovary's importance in fertility and endocrine health, functional attributes of ovarian cells are largely uncharacterized. Here, we profiled >18,000 genes in 257 regions from the ovaries of two premenopausal donors to examine the functional units in the ovary. We also generated single-cell RNA sequencing data for 21,198 cells from three additional donors and identified four major cell types and four immune cell subtypes. Custom selection of sampling areas revealed distinct gene activities for oocytes, theca, and granulosa cells. These data contributed panels of oocyte-, theca-, and granulosa-specific genes, thus expanding the knowledge of molecular programs driving follicle development. Serial samples around oocytes and across the cortex and medulla uncovered previously unappreciated variation of hormone and extracellular matrix remodeling activities. This combined spatial and single-cell atlas serves as a resource for future studies of rare cells and pathological states in the ovary.

Maturation and culture affect the metabolomic profile of oocytes and follicular cells in young and old mares

Introduction: Oocytes and follicular somatic cells within the ovarian follicle are altered during maturation and after exposure to culture in vitro. In the present study, we used a nontargeted metabolomics approach to assess changes in oocytes, cumulus cells, and granulosa cells from dominant, follicular-phase follicles in young and old mares. Methods: Samples were collected at three stages associated with oocyte maturation: (1) GV, germinal vesicle stage, prior to the induction of follicle/oocyte maturation in vivo; (2) MI, metaphase I, maturing, collected 24 h after induction of maturation in vivo; and (3) MIIC, metaphase II, mature with collection 24 h after induction of maturation in vivo plus 18 h of culture in vitro. Samples were analyzed using gas and liquid chromatography coupled to mass spectrometry only when all three stages of a specific cell type were obtained from the same mare. Results and Discussion: Significant differences in metabolite abundance were most often associated with MIIC, with some of the differences appearing to be linked to the final stage of maturation and others to exposure to culture medium. While differences occurred for many metabolite groups, some of the most notable were detected for energy and lipid metabolism and amino acid abundance. The study demonstrated that metabolomics has potential to aid in optimizing culture methods and evaluating cell culture additives to support differences in COCs associated with maternal factors.

The molecular characteristic analysis of TRIB2 gene and its expressional patterns in Bos grunniens tissue and granulosa cells

Tribbles homolog 2 (TRIB2) plays an important role in the follicular development of female mammals. However, its expression and function in the yak (Bos grunniens) are still unclear. In this study, we predicted the molecular characteristics of TRIB2, and revealed its expression pattern in yak (Bos grunniens) tissues and ovarian granulosa cells. We cloned the full length of the yak TRIB2 gene obtained by RT-PCR was 1368 bp and the coding sequence (CDS) was 624 bp, encoding 207 amino acids (AA). Homology analysis showed that the yak TRIB2 is highly conserved among species. TRIB2 was detected to be extensively expressed in seven tissues of the yak liver, spleen, lung, kidney, ovary, oviduct and uterus by qPCR. The expression of TRIB2 mRNA in the ovary during gestation was significantly lower than that in the non-pregnant (p < 0.05). At each stage of follicle development, the TRIB2 mRNA in granulosa cells showed a significant upward trend with the development of follicles. The expression of TRIB2 gradually decreased with the increase of the culture time of the granulosa cells in vitro. In conclusion, these results suggest that TRIB2 may play an important role in the follicular development of yaks.

Polyamines in Ovarian Aging and Disease

Ovarian aging and disease-related decline in fertility are challenging medical and economic issues with an increasing prevalence. Polyamines are a class of polycationic alkylamines widely distributed in mammals. They are small molecules essential for cell growth and development. Polyamines alleviate ovarian aging through various biological processes, including reproductive hormone synthesis, cell metabolism, programmed cell death, etc. However, an abnormal increase in polyamine levels can lead to ovarian damage and promote the development of ovarian disease. Therefore, polyamines have long been considered potential therapeutic targets for aging and disease, but their regulatory roles in the ovary deserve further investigation. This review discusses the mechanisms by which polyamines ameliorate human ovarian aging and disease through different biological processes, such as autophagy and oxidative stress, to develop safe and effective polyamine targeted therapy strategies for ovarian aging and the diseases.

Equine maternal aging affects the metabolomic profile of oocytes and follicular cells during different maturation time points

Introduction: Oocyte quality and fertility decline with advanced maternal age. During maturation within the ovarian follicle, the oocyte relies on the associated somatic cells, specifically cumulus and granulosa cells, to acquire essential components for developmental capacity. Methods: A nontargeted metabolomics approach was used to investigate the effects of mare age on different cell types within the dominant, follicular-phase follicle at three time points during maturation. Metabolomic analyses from single oocytes and associated cumulus and granulosa cells allowed correlations of metabolite abundance among cell types. Results and Discussion: Overall, many of the age-related changes in metabolite abundance point to Impaired mitochondrial metabolic function and oxidative stress in oocytes and follicular cells. Supporting findings include a higher abundance of glutamic acid and triglycerides and lower abundance of ceramides in oocytes and somatic follicular cells from old than young mares. Lower abundance of alanine in all follicular cell types from old mares, suggests limited anaerobic energy metabolism. The results also indicate impaired transfer of carbohydrate and free fatty acid substrates from cumulus cells to the oocytes of old mares, potentially related to disruption of transzonal projections between the cell types. The identification of age-associated alterations in the abundance of specific metabolites and their correlations among cells contribute to our understanding of follicular dysfunction with maternal aging.

Hormones and Aging: An Endocrine Society Scientific Statement

Multiple changes occur across various endocrine systems as an individual ages. The understanding of the factors that cause age-related changes and how they should be managed clinically is evolving. This statement reviews the current state of research in the growth hormone, adrenal, ovarian, testicular, and thyroid axes, as well as in osteoporosis, vitamin D deficiency, type 2 diabetes, and water metabolism, with a specific focus on older individuals. Each section describes the natural history and observational data in older individuals, available therapies, clinical trial data on efficacy and safety in older individuals, key points, and scientific gaps. The goal of this statement is to inform future research that refines prevention and treatment strategies in age-associated endocrine conditions, with the goal of improving the health of older individuals.

A Role of PI3K/Akt Signaling in Oocyte Maturation and Early Embryo Development

A serine/threonine-specific protein kinase B (PKB), also known as Akt, is a key factor in the phosphoinositide 3-kinase (PI3K)/Akt signaling pathway that regulates cell survival, metabolism and proliferation. Akt phosphorylates many downstream specific substrates, which subsequently control the nuclear envelope breakdown (NEBD), centrosome maturation, spindle assembly, chromosome segregation, and cytokinesis. In vertebrates, Akt is also an important player during oogenesis and preimplantation development. In the signaling pathways regulating mRNA translation, Akt is involved in the control of mammalian target of rapamycin complex 1 (mTORC1) and thereby regulates the activity of a translational repressor, the eukaryotic initiation factor 4E (eIF4E) binding protein 1 (4E-BP1). In this review, we summarize the functions of Akt in mitosis, meiosis and early embryonic development. Additionally, the role of Akt in the regulation of mRNA translation is addressed with respect to the significance of this process during early development.

miR-200b/MYBL2/CDK1 suppresses proliferation and induces senescence through cell cycle arrest in ovine granulosa cells

Normal growth of granulosa cells (GCs) is essential for follicular development. miR-200b plays a vital role in litter size, estrous cycle, ovulation, and follicular development in sheep. However, it is unclear that the specific effect and regulatory mechanism of miR-200b on ovine GCs. miR-200b mimic inhibited GCs proliferation and induced cellular senescence through downregulating mitochondrial membrane potential (MMP), concentration of ATP and mitochondrial respiratory chain complex Ⅰ, and upregulating SA-β-gal positive rate and ROS production. A total of 597 differentially expressed genes were identified by RNA-Seq in GCs transfected with miR-200b mimic and mimic NC, and they were involved in cell cycle and cellular senescence. miR-200b directly targeted and downregulated MYBL2 and CDK1. Overexpression of MYBL2 promoted GCs proliferation and genes expression (CDK1, CDC20, MAD2L1 and FOXM1), which were suppressed by miR-200b mimic. Furthermore, MYBL2 negatively regulated miR-200b-induced GC senescence. In conclusion, miR-200b/MYBL2/CDK1 regulated proliferation and senescence through cell cycle pathway in ovine granulosa cells. Our study provides a novel insight that miR-200b regulates ovine follicular development.

The role of oxidative stress in ovarian aging: a review

Ovarian aging refers to the process by which ovarian function declines until eventual failure. The pathogenesis of ovarian aging is complex and diverse; oxidative stress (OS) is considered to be a key factor. This review focuses on the fact that OS status accelerates the ovarian aging process by promoting apoptosis, inflammation, mitochondrial damage, telomere shortening and biomacromolecular damage. Current evidence suggests that aging, smoking, high-sugar diets, pressure, superovulation, chemotherapeutic agents and industrial pollutants can be factors that accelerate ovarian aging by exacerbating OS status. In addition, we review the role of nuclear factor E2-related factor 2 (Nrf2), Sirtuin (Sirt), mitogen-activated protein kinase (MAPK), protein kinase B (AKT), Forkhead box O (FoxO) and Klotho signaling pathways during the process of ovarian aging. We also explore the role of antioxidant therapies such as melatonin, vitamins, stem cell therapies, antioxidant monomers and Traditional Chinese Medicine (TCM), and investigate the roles of these supplements with respect to the reduction of OS and the improvement of ovarian function. This review provides a rationale for antioxidant therapy to improve ovarian aging.