ABSTRACT: Ovarian aging leads to diminished fertility, dysregulated endocrine signaling, and increased chronic disease burden. These effects begin to emerge long before follicular exhaustion. Around 35 years old, women experience a sharp decline in fertility, corresponding to declines in oocyte quality. However, the field lacks a cellular map of the transcriptomic changes in the aging ovary to identify drivers of ovarian decline. To fill this gap, we performed single-cell RNA sequencing on ovarian tissue from young (3-month-old) and reproductively aged (9-month-old) mice. Our analysis revealed a doubling of immune cells in the aged ovary, with T and B lymphocyte proportions increasing most. We also discovered an age-related upregulation of alternative macrophage and downregulation of collagenase pathways in stromal fibroblasts. Overall, follicular cells (especially granulosa and theca) display stress response, immunogenic, and fibrotic signaling pathway inductions with aging. These changes are more exaggerated in the atretic granulosa cells but are also observed in healthy antral and preantral granulosa cells. Moreover, we did not observe age-related changes in markers of cellular senescence in any cellular population with advancing age, despite specific immune cells expressing senescence-related genes across both timepoints. This report raises several new hypotheses that could be pursued to elucidate mechanisms responsible for ovarian aging phenotypes.
Project description:The understanding of how aging affects the cellular and molecular components of the human ovary and contributes to age-related fertility decline is still limited. Here, we systematically characterize human ovarian aging by combining single-cell RNA sequencing and spatial transcriptomics. We provide a comprehensive understanding of human ovarian aging and a resource for the development of new diagnostic biomarkers and therapeutic strategies.
Project description:Molecular mechanisms of ovarian aging and female age-related fertility decline remain unclear. We surveyed the single-cell transcriptomic landscape of ovaries from young and aged non-human primates (NHPs) and identified seven ovarian cell types with distinct gene expression signatures, including oocyte and six types of ovarian somatic cells. In-depth dissection of gene expression dynamics of oocytes revealed four subtypes at sequential and stepwise developmental stages. Further analysis of cell type-specific aging-associated transcriptional changes uncovered the disturbance of antioxidant signaling specific to early-stage oocytes and granulosa cells, indicative of oxidative damage as a crucial factor in ovarian functional decline with age. Additionally, inactivated antioxidative pathways, increased reactive oxygen species and apoptosis were observed in granulosa cells from aged women. This study provides comprehensive understanding of the cell type-specific mechanisms underlying primate ovarian aging at single-cell resolution, revealing new diagnostic biomarkers and potential therapeutic targets for age-related human ovarian disorders.
Project description:FOXL2 is a transcription factor essential for female fertility, expressed in somatic cells of the ovary, notably granulosa cells. In the mouse, Foxl2 deletion leads to partial sex reversal postnatally. However, deletion of the gene in 8-week-old females leads to granulosa to Sertoli cell transdifferentiation. We hypothesised that different outcomes of Foxl2 deletion in embryonic versus adult ovary may depend on a different role played across ovarian development. Therefore, we characterised the dynamics of gene expression and chromatin accessibility changes in purified murine granulosa cells across key developmental stages (E14.5, 1 and 8 weeks). We then performed genome-wide identification of FOXL2 target genes and on-chromatin interacting partners by ChIP-SICAP. We found that FOXL2 regulates more genes at postnatal stages, through the interaction with factors regulating primordial follicle activation (PFA), such as NR5A2, and others regulating steroidogenesis including AR and ESR2. As a proof of principle experiment, we chose one FOXL2 interactor, Ubiquitin specific protease 7 (USP7) and showed that deletion of this gene in granulosa cells leads to a blockage of PFA, impaired ovary development and sterility. Our study constitutes a comprehensive resource for exploration of the molecular mechanisms of ovarian development and causes of female infertility.
Project description:The rising global incidence of inflammatory bowel disease (IBD) is associated with reduced levels of anti-Müllerian hormone (AMH), a key biomarker for premature ovarian insufficiency (POI), highlighting reproductive risks for women of childbearing age. To investigate the connection between IBD and ovarian aging, we used a dextran sodium sulfate (DSS)-induced mouse model of IBD and assessed reproductive outcomes, including ovarian reserve, folliculogenesis, hormone profiles, and estrous cyclicity. Transcriptomic analysis of ovarian tissue showed that IBD upregulates genes associated with aging. Gene Ontology enrichment pointed to signaling pathways involved in cellular senescence, oxidative stress response, and senescence-associated secretory phenotypes. By integrating our ovarian transcriptomic data with single-cell RNA-seq datasets from young (3-month) and aged (9-month) mouse ovaries, we found significant parallels between IBD-induced transcriptional changes and natural ovarian aging. Flow cytometry confirmed elevated levels of T cells, CD8+ T cells, and macrophages in the ovaries, indicating localized immune activation. Similar systemic immune changes were observed in peripheral blood mononuclear cells, with expanded T cell and macrophage populations. TUNEL assays and qPCR further validated accelerated ovarian aging in IBD mice, showing increased granulosa cell apoptosis and upregulated aging-related markers. Notably, even after an 89-day recovery period following DSS treatment, persistent deficits in follicular counts, hormonal balance, and estrous regularity indicated irreversible ovarian dysfunction. Our findings demonstrate that IBD triggers ovarian inflammation, depletes ovarian reserve, and accelerates aging processes, leading to long-term reproductive impairment. This study elucidates the mechanistic links between IBD and POI, providing insights for therapeutic strategies to mitigate fertility risks in affected women.
Project description:The ovary is the first organ to age in the human body, affecting both fertility and overall health. However, the biological mechanisms underlying human ovarian aging remain poorly understood. Here we present a comprehensive single-nuclei multi-omics atlas of four young (ages 23–29 years) and four reproductively aged (ages 49–54 years) human ovaries. Our analyses reveal coordinated changes in transcriptomes and chromatin accessibilities across cell types in the ovary during aging, notably mTOR signaling being a prominent ovary-specific aging pathway. Cell-type-specific regulatory networks reveal enhanced activity of the transcription factor CEBPD across cell types in the aged ovary. Integration of our multi-omics data with genetic variants associated with age at natural menopause demonstrates a global impact of functional variants on gene regulatory networks across ovarian cell types. We nominate functional non-coding regulatory variants, their target genes and ovarian cell types and regulatory mechanisms. This atlas provides a valuable resource for understanding the cellular, molecular and genetic basis of human ovarian aging.
Project description:Depletion of oocytes and follicles and reduced oocyte quality contribute to age-associated ovarian senescence and infertility. Telomere shortening and altered methylation make two major contributions to general aging. Resveratrol acts as anti-oxidant and Sirt1 activator to alleviate aging including reproductive aging. It remains elusive whether resveratrol can reprogram the aging epigenome. We sought to examine aging ovarian epigenome and the potential effects of resveratrol by combined analysis of telomere length, transcriptome and methylome mainly in oocytes and also in granulosa cells, two major cell types in the ovary.
Project description:Depletion of oocytes and follicles and reduced oocyte quality contribute to age-associated ovarian senescence and infertility. Telomere shortening and altered methylation make two major contributions to general aging. Resveratrol acts as anti-oxidant and Sirt1 activator to alleviate aging including reproductive aging. It remains elusive whether resveratrol can reprogram the aging epigenome. We sought to examine aging ovarian epigenome and the potential effects of resveratrol by combined analysis of telomere length, transcriptome and methylome mainly in oocytes and also in granulosa cells, two major cell types in the ovary.
Project description:Chromosome aneuploidy increases in oocytes with maternal age, and is considered the leading cause for the increased incidence of infertility, miscarriage, and birth defects. Using mRNA-Sequencing of oocytes from 12 month old mouse versus 3 month young mouse, we identified a spindle assembly checkpoint gene, BubR1, whose expression was significantly decreased. We employed a mRNA microinjection based approach to increase BubR1 expression in aging oocytes. We find that increased expression of BubR1 protects against aneuploidy and chromosome misalignment in aging oocytes. After in vitro fertilization, the embryos derived from BubR1 increased expression aging oocytes exhibited chromosome stability as robust as those of the young ones. Furthermore, following embryo transfer, these embryos showed greatly improved developmental competency, with comparable levels of full-term development to those of the young ones. These results indicate that the decline in oocyte quality may be reversible and could lead to treatments that prolong female fertility. Examination of the effect of maternal aging on the mRNA expression in the mature oocytes of the female mice. Naturally ovulated mature oocytes (MII stage) were collected from 6 young (3 month) and 6 aging (12 month) female mice (3 oocytes per mice, 18 oocytes for each group).
Project description:The ovarian function decreases in parallel with aging. So do the quantity of follicles, which is about 1-2 million at birth, while only about 1000 primordial follicles are left at menopause. Folliculogenesis is vital for ovary function, no matter the synthesis of female hormones or ovulation, yet the mechanisms for its changing with increasing age are not fully understood. To further understand the age-related molecular changes in the process of folliculogenesis, we performed microarray gene expression profile analysis using total RNA extracted from young (9 weeks old) and old (32 weeks old) mouse ovarian secondary follicles. The results of our current microarray study revealed that there were 371 (≥2 fold, q-value ≤0.05) genes differentially expressed in which 174 genes were up-regulated and 197 genes were down-regulated in old mouse ovarian secondary follicles compared to young mouse ovarian secondary follicles. The gene ontology and KEGG pathway analysis of differentially expressed genes uncovered critical biological functions such as immune system process, aging, transcription, DNA replication, DNA repair, protein stabilization and apoptotic process were affected in the process of aging. The considerable changes in gene expression profile may have an adverse influence on follicle quality and folliculogenesis. Our study provided information on the processes that may contribute to age-related decline in ovarian function.
Project description:Samul-tang (SM), a traditional herbal medicine is used to treat menstrual irregularities and infertility. The mechanism underlying the role of SM in ovary function needs elucidation. In this study, the influence of SM administration on the ovarian reserve of aged mice was investigated. Female BALB/c mice (8 and 40 weeks-old) were administered with distilled water (young or old group) or SM for 4 weeks. SM administration prevented age-related ovarian follicle loss in mice. Quality of oocytes and blastocysts were enhanced in SM-administrated mice compared to those of non-treated old mice. Further, SM administration increased the pregnancy rate and number of litters. SM triggered changes in aging-related genes that are linked to the RAS-mediated pathway. Thus, we demonstrate that SM can be used to increase the oocyte yield in aged women, potentially improving age-related cognitive decline in the ovarian reserve.