Single-Cell Transcriptomic Atlas of Primate Ovarian Aging

Integration of single-cell sequencing and bulk transcriptome data develops prognostic markers based on PCLAF+ stem-like tumor cells using artificial neural network in gastric cancer

Background

Gastric cancer stem cells (GCSCs) are important tumour cells involved in tumourigenesis and gastric cancer development. However, their clinical value remains unclear due to the limitations of the available technologies. This study aims to explore the clinical significance of GCSCs, their connection to the tumour microenvironment, and their underlying molecular mechanisms.

Methods

Stem-like tumour cells were identified by mining single-cell transcriptomic data from multiple samples. Integrated analysis of single-cell and bulk transcriptome data was performed to analyse the role of stem-like tumour cells in predicting clinical outcomes by introducing the intermediate variable mRNA stemness degree (SD). Consensus clustering analysis was performed to develop an SD-related molecular classification strategy to assess the clinical characteristics in gastric cancer. A prognostic model was constructed using a customized approach that comprehensively considered SD-related gene signatures based on an artificial neural network.

Results

By analysing single-cell data and validating immunofluorescence results, we identified a PCLAF+ stem-like tumour cell population in GC. By calculating SD, we observed that PCLAF+ stem-like tumour cells were associated with poor prognosis and certain clinical features. The SD was negatively correlated with the abundance of most immune cell types. Furthermore, we proposed an SD-related classification method and prognostic model. In addition, the customised prognostic model can be used to predict whether a patient respond to PD-1/PD-L1 immunotherapy.

Conclusion

We identified a cluster of stem-like cells and elucidated their clinical significance, highlighting the possibility of their use as immunotherapeutic targets.

Identification of apelin/APJ signaling dysregulation in a human iPSC-derived granulosa cell model of Turner syndrome

The interaction between germ cells and somatic cells in the ovaries plays a crucial role in establishing the follicle reserve in mammals. Turner syndrome (TS) predominantly affects females who have a partial or complete loss of one X chromosome. Our understanding of the role that granulosa cells (GCs) play in TS disease progression and pathogenesis remains limited. In this study, we achieved GC differentiation efficiency of up to 80% from iPSCs. When attempting to replicate the differentiation process of embryonic granulosa cells, we observed the downregulation of specific genes-GATA4, FOXL2, AMHR2, CYP19A1, and FSH-in Turner syndrome-derived granulosa cells (TS-GCs). Additionally, we identified dysregulation of the cell cycle in TS-GCs. To uncover the endogenous defects in TS-GCs, we compared global transcriptome patterns between iPSC-derived granulosa cells from healthy individuals and those with Turner syndrome. The apelin/APJ pathway exhibited differential signaling between the healthy and TS groups. Supplementation with apelin ligands and activation of apelin/APJ downstream signaling via Akt/PKB restored cell cycle progression and marker gene expression. We hypothesize that during early embryonic development, failures in apelin/APJ signaling in GCs of Turner syndrome patients lead to abnormalities in ovarian development, ultimately resulting in early oocyte loss and infertility.

The assembly and activation of the PANoptosome promote porcine granulosa cell programmed cell death during follicular atresia

BACKGROUND

Follicular atresia significantly impairs female fertility and hastens reproductive senescence. Apoptosis of granulosa cells is the primary cause of follicular atresia. Pyroptosis and necroptosis, as additional forms of programmed cell death, have been reported in mammalian cells. However, the understanding of pyroptosis and necroptosis pathways in granulosa cells during follicular atresia remains unclear. This study explored the effects of programmed cell death in granulosa cells on follicular atresia and the underlying mechanisms.

RESULTS

The results revealed that granulosa cells undergo programmed cell death including apoptosis, pyroptosis, and necroptosis during follicular atresia. For the first time, we identified the formation of a PANoptosome complex in porcine granulosa cells. This complex was initially identified as being composed of ZBP1, RIPK3, and RIPK1, and is recruited through the RHIM domain. Additionally, we demonstrated that caspase-6 is activated and cleaved, interacting with RIPK3 as a component of the PANoptosome. Heat stress may exacerbate the activation of the PANoptosome, leading to programmed cell death in granulosa cells.

CONCLUSIONS

Our data identified the formation of a PANoptosome complex that promoted programmed cell death in granulosa cells during the process of follicular atresia. These findings provide new insights into the molecular mechanisms underlying follicular atresia.

Stem cell transplantation extends the reproductive life span of naturally aging cynomolgus monkeys

The ovary is crucial for female reproduction and health, as it generates oocytes and secretes sex hormones. Transplantation of mesenchymal stem cells (MSCs) has been shown to alleviate pathological ovarian aging. However, it is unclear whether MSCs could benefit the naturally aging ovary. In this study, we first examined the dynamics of ovarian reserve of Chinese women during perimenopause. Using a naturally aging cynomolgus monkey (Macaca fascicularis) model, we found that transplanting human embryonic stem cells-derived MSC-like cells, which we called M cells, into the aging ovaries significantly decreased ovarian fibrosis and DNA damage, enhanced secretion of sex hormones and improved fertility. Encouragingly, a healthy baby monkey was born after M-cell transplantation. Moreover, single-cell RNA sequencing analysis and in vitro functional validation suggested that apoptosis, oxidative damage, inflammation, and fibrosis were mitigated in granulosa cells and stromal cells following M-cell transplantation. Altogether, these findings demonstrate the beneficial effects of M-cell transplantation on aging ovaries and expand our understanding of the molecular mechanisms underlying ovarian aging and stem cell-based alleviation of this process.

Elevated N-glycosylated cathepsin L impairs oocyte function and contributes to oocyte senescence during reproductive aging

Age-related declines in oocyte quality and ovarian function are pivotal contributors to female subfertility in clinical settings. Yet, the mechanisms driving ovarian aging and oocyte senescence remain inadequately understood. The present study evaluated the alterations in N-glycoproteins associated with ovarian aging and noted a pronounced elevation in N221 glycopeptides of cathepsin L (Ctsl) in the ovaries of reproductive-aged mice (8-9 months and 11-12 months) compared to younger counterparts (6-8 weeks). Subsequent analysis examined the involvement of Ctsl in oocyte aging and demonstrated a significant elevation in Ctsl levels in aged oocytes. Further, it was revealed that the overexpression of Ctsl in young oocytes substantially diminished their quality, while oocytes expressing an N221-glycosylation mutant of Ctsl did not suffer similar quality degradation. This finding implies that the N221 glycosylation of Ctsl is pivotal in modulating its effect on oocyte health. The introduction of a Ctsl inhibitor into the culture medium restored oocyte quality in aged oocytes by enhancing mitochondrial function, reducing accumulated reactive oxygen species (ROS), lowering apoptosis, and recovering lysosome capacity. Furthermore, the targeted downregulation of Ctsl using siRNA microinjection in aged oocytes enhanced fertilization capability and blastocyst formation, affirming the role of Ctsl knockdown in fostering oocyte quality and embryonic developmental potential. In conclusion, these findings underscore the detrimental effects of high expression of N-glycosylated Ctsl on oocyte quality and its contribution to oocyte senescence, highlighting it as a potential therapeutic target to delay ovarian aging and enhance oocyte viability.

Investigation of human aging at the single-cell level

Human aging is characterized by a gradual decline in physiological functions and an increased susceptibility to various diseases. The complex mechanisms underlying human aging are still not fully elucidated. Single-cell sequencing (SCS) technologies have revolutionized aging research by providing unprecedented resolution and detailed insights into cellular diversity and dynamics. In this review, we discuss the application of various SCS technologies in human aging research, encompassing single-cell, genomics, transcriptomics, epigenomics, and proteomics. We also discuss the combination of multiple omics layers within single cells and the integration of SCS technologies with advanced methodologies like spatial transcriptomics and mass spectrometry. These approaches have been essential in identifying aging biomarkers, elucidating signaling pathways associated with aging, discovering novel aging cell subpopulations, uncovering tissue-specific aging characteristics, and investigating aging-related diseases. Furthermore, we provide an overview of aging-related databases that offer valuable resources for enhancing our understanding of the human aging process.

Exploring the anti-ovarian aging mechanism of He's Yangchao formula: Insights from multi-omics analysis in naturally aged mice

BACKGROUND

The rapid acceleration of female reproductive aging has become a major public health concern. He's Yangchao formula (HSYC), a compound comprising eight herbs, has demonstrated efficacy in enhancing ovarian function. Thus, an in-depth study of its anti-ovarian aging mechanism is required.

PURPOSE

To evaluate the anti-ovarian aging effect of HSYC in naturally aged mice and investigate the underlying mechanism by analyzing the gut microbiota (GM), metabolome, and transcriptome.

METHODS

Young and advanced maternal age (AMA) mice were selected for this study. Hematoxylin and eosin staining, fluorescence staining, western blotting, and qPCR analyses were used to detect the phenotypes associated with ovarian aging. Subsequently, analyses of the GM, transcriptome, and metabolome analyses were performed to explore the potential mechanisms of action of HSYC. Finally, in vivo and in vitro experiments were performed to verify potential therapeutic mechanisms.

RESULTS

HSYC promoted follicular development in AMA mice and ameliorated age-related mitochondrial dysfunction, apoptosis, and defects in DNA damage repair. GM analysis revealed that HSYC treatment significantly increased the abundance of Akkermansia and Turicibacter. Transcriptome and metabolome analyses showed that HSYC might mitigate ovarian aging by regulating metabolic pathways, amino acid metabolism, glutathione metabolism, and the synthesis of pantothenic acid and coenzyme A. Combined transcriptomic and metabolomic analyses identified the glutathione metabolic pathway as the key pathway through which HSYC counteracts ovarian aging. Additional experimental verification confirmed that HSYC upregulated the glutathione metabolic genes GPX8, GSTA1, and GSTA4, increased glutathione-related products (GSH), and reduced ROS levels.

CONCLUSIONS

HSYC exerts beneficial therapeutic effects on ovarian aging by regulating multiple endogenous metabolites, targets, and metabolic pathways, with an emphasis on its anti-ovarian aging effects through the glutathione metabolic pathway. These findings underscore the innovative potential of HSYC in addressing ovarian aging and offer a novel therapeutic approach that targets multiple biological pathways to improve the reproductive health of women with AMA..

A Single-Cell Metabolic Profiling Characterizes Human Aging via SlipChip-SERS

Metabolic dysregulation is a key driver of cellular senescence, contributing to the progression of systemic aging. The heterogeneity of senescent cells and their metabolic shifts are complex and unexplored. A microfluidic SlipChip integrated with surface-enhanced Raman spectroscopy (SERS), termed SlipChip-SERS, is developed for single-cell metabolism analysis. This SlipChip-SERS enables compartmentalization of single cells, parallel delivery of saponin and nanoparticles to release intracellular metabolites and to realize SERS detection with simple slipping operations. Analysis of different cancer cell lines using SlipChip-SERS demonstrated its capability for sensitive and multiplexed metabolic profiling of individual cells. When applied to human primary fibroblasts of different ages, it identified 12 differential metabolites, with spermine validated as a potent inducer of cellular senescence. Prolonged exposure to spermine can induce a classic senescence phenotype, such as increased senescence-associated β-glactosidase activity, elevated expression of senescence-related genes and reduced LMNB1 levels. Additionally, the senescence-inducing capacity of spermine in HUVECs and WRL-68 cells is confirmed, and exogenous spermine treatment increased the accumulation and release of H2O2. Overall, a novel SlipChip-SERS system is developed for single-cell metabolic analysis, revealing spermine as a potential inducer of senescence across multiple cell types, which may offer new strategies for addressing ageing and ageing-related diseases.

Photobiomodulation ameliorates ovarian aging by alleviating oxidative stress and inflammation damage and improving mitochondrial function

Ovarian aging is a serious clinical concern. Few safe and effective methods are currently available to improve ovarian functions. Photobiomodulation (PBM) is a safe and noninvasive physical therapy that can modulate a series of biological processes. Recently, several studies have noted its potential to improve the function of ovary and reproductive cells. However, the effects of PBM treatment on natural ovarian aging remain unclear. In this study, we used a naturally reproductive aging mouse model to observe the effect of PBM on ovarian function. Young and aged female ICR mice were treated with or without PBM for 2 months. PBM was performed using a semiconductor InGaAlP laser emitting at 650 nm (80 mW, 6.7 mW/cm2 for 5 or 10 min, resulting in a dose of 2 or 4 J/cm2, respectively). After treatment, the effects of PBM and its role in oxidative stress, inflammation, and mitochondrial function were investigated. We found that PBM (4 J/cm2) effectively recovered the levels of sex hormones, increased the number of primordial and growing follicles, improved angiogenesis, and decreased cell apoptosis in naturally aged mice. Moreover, PBM reduced oxidative stress, inhibited chronic ovarian inflammation, and improved mitochondrial function in aged ovaries. Similar protective effects of PBM were observed in a hydrogen peroxide-induced oxidative stress model of human granulosa cell line (KGN) in vitro. Increased cell viability, cell proliferation, hormone secretion, mitochondrial membrane potential, and adenosine triphosphate levels and decreased apoptosis and oxidative stress were detected in KGN cells after PBM treatment. Collectively, this study suggest that PBM treatment is beneficial for restoring ovarian function in naturally reproductive aging mice and has a significant protective effect against oxidative stress damage in KGN cells. The mechanisms underlying the benefits of PBM in ovarian aging include antioxidant stress, reduction of inflammation, and preservation of mitochondrial function. Therefore, this study emphasizes the potential of PBM as a therapeutic intervention to ameliorate ovarian aging.

Adolescent exposure to a mixture of per- and polyfluoroalkyl substances (PFAS) depletes the ovarian reserve, increases ovarian fibrosis, and alters the Hippo pathway in adult female mice

Per- and polyfluoroalkyl substances (PFAS) are synthetic chemicals known for their environmental persistence and resistance to biodegradation. This study investigated the impact of adolescent exposure to a PFAS mixture on adult ovarian function. Female CD-1 mice were orally exposed to vehicle control or a PFAS mixture (comprised of perfluorooctanoic acid, perfluorooctanesulfonic acid, undecafluoro-2-methyl-3-oxahexanoic acid, and perfluorobutanesulfonic acid) for 15 d. After a 42-d recovery period, reproductive hormones, ovarian fibrosis, and ovarian gene and protein expression were analyzed using ELISA, Picrosirius red staining, qPCR, and immunoblotting, respectively. Results revealed that PFAS exposure did not affect adult body or organ weight, although ovarian weight slightly decreased. PFAS-exposed mice exhibited a disturbed estrous cycle, with less time spent in proestrus than control mice. Follicle counting indicated a reduction in primordial and primary follicles. Serum analysis revealed no changes in steroid hormones, follicle-stimulating hormone, or anti-Müllerian hormone, but a significant increase in luteinizing hormone was observed in PFAS-treated mice. Ovaries collected from PFAS-treated mice had increased mRNA transcripts for steroidogenic enzymes and fatty acid synthesis-related genes. PFAS exposure also increased collagen content in the ovary. Additionally, serum tumor necrosis factor-α levels were higher in PFAS-treated mice. Finally, transcripts and protein abundance for Hippo pathway components were upregulated in the ovaries of the PFAS-treated mice. Overall, these findings suggest that adolescent exposure to PFAS can disrupt ovarian function in adulthood.

Metformin decelerates aging clock in male monkeys

In a rigorous 40-month study, we evaluated the geroprotective effects of metformin on adult male cynomolgus monkeys, addressing a gap in primate aging research. The study encompassed a comprehensive suite of physiological, imaging, histological, and molecular evaluations, substantiating metformin's influence on delaying age-related phenotypes at the organismal level. Specifically, we leveraged pan-tissue transcriptomics, DNA methylomics, plasma proteomics, and metabolomics to develop innovative monkey aging clocks and applied these to gauge metformin's effects on aging. The results highlighted a significant slowing of aging indicators, notably a roughly 6-year regression in brain aging. Metformin exerts a substantial neuroprotective effect, preserving brain structure and enhancing cognitive ability. The geroprotective effects on primate neurons were partially mediated by the activation of Nrf2, a transcription factor with anti-oxidative capabilities. Our research pioneers the systemic reduction of multi-dimensional biological age in primates through metformin, paving the way for advancing pharmaceutical strategies against human aging.

Zuogui Pills alleviate cyclophosphamide-induced ovarian aging by reducing oxidative stress and restoring the stemness of oogonial stem cells through the Nrf2/HO-1 signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Zuogui Pill (ZGP) is a traditional herbal formula of Chinese Medicine with a long history of use in alleviating ovarian aging.

AIM OF THE STUDY

To examine the impact of ZGP on oxidative stress and the stemness of oogonial stem cells (OSCs) in cyclophosphamide (CTX)-induced ovarian aging, as well as its molecular mechanisms involving the nuclear factor erythroid 2-related factor 2 (Nrf2, NFE2L2)/heme oxygenase-1 (HO-1, Hmox1) pathway.

MATERIALS AND METHODS

Female Sprague-Dawley (SD) rats were randomly divided into seven groups: control, model (CTX), estradiol valerate (EV, 0.103 mg/kg), ZGP-L (low dose Zuogui Pill, 1.851 g/kg), ZGP-H (high dose Zuogui Pill, 3.702 g/kg), ML385 (30 mg/kg), and ML385+ZGP-L. After CTX modeling, the EV, ZGP-L, ZGP-H, and ML385+ZGP-L groups were treated by gavage for 8 weeks, while the ML385 and ML385+ZGP-L groups were administered the Nrf2 antagonist ML385 twice a week. OSCs were isolated after modeling and then treated with drug serum containing 10% ZGP or 10 μM ML385. The general conditions of the rats, including body weight, ovarian weight/body weight ratio, and estrous cycle, were observed. Ovarian ultrastructure, follicle and corpus luteum counts were assessed via hematoxylin and eosin (H&E) staining. Serum hormone levels were measured using enzyme-linked immunosorbent assay (ELISA). Nrf2/HO-1 pathway, stem cell, germ cell, and cell cycle biomarkers were analyzed by qPCR and Western blot. Cell viability was assessed by cell counting kit-8 (CCK-8) assay. Oxidative stress biomarkers were evaluated using flow cytometry and assay kits. Immunofluorescence was employed to detect and locate OSCs in the ovary, quantify the average fluorescence intensity, and identify OSCs.

RESULTS

After ZGP treatment, rats with CTX-induced ovarian aging exhibited improved general condition, increased body weight, higher total ovarian weight to body weight ratio, and a restoration of the estrous cycle similar to the control group. Serum levels of estradiol (E2) and follicle stimulating hormone (FSH), two sex hormones, were also improved. Ovarian ultrastructure and follicle count at all stages showed improvement. Moreover, the viability and proliferation capacity of OSCs were enhanced following ZGP intervention. The Nrf2/HO-1 pathway was found to be down-regulated in CTX-induced aging ovarian OSCs. However, ZGP reversed this effect by activating the expression of Nrf2, HO-1, and NAD(P)H oxidoreductase 1 (NQO1), increasing the activity of antioxidant enzymes superoxide dismutase (SOD) and glutathione peroxidase (GSH-PX), and reducing the accumulation of malonaldehyde (MDA) and reactive oxygen species (ROS), thus restoring resistance to oxidative stress. Additionally, ZGP improved the cell cycle of OSCs, up-regulated the expression of Cyclin D1 and Cyclin E1, restored cell stemness, promoted proliferation, enhanced the expression of cell stemness markers octamer-binding transcription factor 4 (Oct4) and mouse VASA homolog (MVH), and down-regulated the expression of P21, thereby inhibiting apoptosis. The therapeutic effects of ZGP against oxidative stress and restoration of cell stemness were attenuated following inhibition of the Nrf2 signaling pathway using ML385.

CONCLUSIONS

ZGP protected against CTX-induced ovarian aging by restoring normal ovarian function, alleviating oxidative stress in aging OSCs, promoting OSCs proliferation, and restoring their stemness in rats, possibly through regulating the Nrf2/HO-1 pathway.

Transcriptomic signatures of WNT-driven pathways and granulosa cell-oocyte interactions during primordial follicle activation

Primordial follicle activation (PFA) is a pivotal event in female reproductive biology, coordinating the transition from quiescent to growing follicles. This study employed comprehensive single-cell RNA sequencing to gain insights into the detailed regulatory mechanisms governing the synchronized dormancy and activation between granulosa cells (GCs) and oocytes with the progression of the PFA process. Wntless (Wls) conditional knockout (cKO) mice served as a unique model, suppressing the transition from pre-GCs to GCs, and disrupting somatic cell-derived WNT signaling in the ovary. Our data revealed immediate transcriptomic changes in GCs post-PFA in Wls cKO mice, leading to a divergent trajectory, while oocytes exhibited modest transcriptomic alterations. Subpopulation analysis identified the molecular pathways affected by WNT signaling on GC maturation, along with specific gene signatures linked to dormant and activated oocytes. Despite minimal evidence of continuous up-regulation of dormancy-related genes in oocytes, the loss of WNT signaling in (pre-)GCs impacted gene expression in oocytes even before PFA, subsequently influencing them globally. The infertility observed in Wls cKO mice was attributed to compromised GC-oocyte molecular crosstalk and the microenvironment for oocytes. Our study highlights the pivotal role of the WNT-signaling pathway and its molecular signature, emphasizing the importance of intercellular crosstalk between (pre-)GCs and oocytes in orchestrating folliculogenesis.

Recent Developments in Single-Cell Metabolomics by Mass Spectrometry─A Perspective

Recent advancements in single-cell (sc) resolution analyses, particularly in sc transcriptomics and sc proteomics, have revolutionized our ability to probe and understand cellular heterogeneity. The study of metabolism through small molecules, metabolomics, provides an additional level of information otherwise unattainable by transcriptomics or proteomics by shedding light on the metabolic pathways that translate gene expression into functional outcomes. Metabolic heterogeneity, critical in health and disease, impacts developmental outcomes, disease progression, and treatment responses. However, dedicated approaches probing the sc metabolome have not reached the maturity of other sc omics technologies. Over the past decade, innovations in sc metabolomics have addressed some of the practical limitations, including cell isolation, signal sensitivity, and throughput. To fully exploit their potential in biological research, however, remaining challenges must be thoroughly addressed. Additionally, integrating sc metabolomics with orthogonal sc techniques will be required to validate relevant results and gain systems-level understanding. This perspective offers a broad-stroke overview of recent mass spectrometry (MS)-based sc metabolomics advancements, focusing on ongoing challenges from a biologist's viewpoint, aimed at addressing pertinent and innovative biological questions. Additionally, we emphasize the use of orthogonal approaches and showcase biological systems that these sophisticated methodologies are apt to explore.

Integrated single-cell and spatial transcriptomics reveal microenvironment disruptions by androgen in mouse ovary

Elevated levels of androgen are risk factors for disrupted follicular maturation in the polycystic ovary syndrome (PCOS), a reproductive disease in women. As essential cell types for follicular maturation, granulosa and thecal cells respond to androgen, but their responses are unclear at the subpopulation level. Using single-cell RNA sequencing and spatial transcriptomics, we examined the subpopulation and function alterations in an androgen-induced PCOS-like mouse model. The results demonstrated that the granulosa cell subset 5 (GC5) was active in inflammation and the thecal cell subtype 2 (TC2) had an enhanced activity in lipid metabolism. The two subsets were expanded in population size and intercellular signaling pathways, such as Ptn-Ncl and Mdk-Ncl. The results reveal that androgen induced landscape and function shifts in the two cell types under the condition of impaired follicular maturation. The study characterizes the ovarian microenvironment in responses to androgen in PCOS mice.

Changes in DNA repair compartments and cohesin loss promote DNA damage accumulation in aged oocytes

Oocyte loss, a natural process that accelerates as women approach their mid-30s, poses a significant challenge to female reproduction. Recent studies have identified DNA damage as a primary contributor to oocyte loss, but the mechanisms underlying DNA damage accumulation remain unclear. Here, we show that aged oocytes have a lower DNA repair capacity and reduced mobility of DNA damage sites compared to young oocytes. Incomplete DNA repair in aged oocytes results in defective chromosome integrity and partitioning, thereby compromising oocyte quality. We found that DNA repair proteins are arranged in spatially distinct DNA repair compartments that form during the late stages of oocyte growth, accompanied by changes in the activity of DNA repair pathways. We demonstrate alterations in these compartments with age, including substantial changes in the levels of key DNA repair proteins and a shift toward error-prone DNA repair pathways. In addition, we show that reduced cohesin levels make aged oocytes more vulnerable to persistent DNA damage and cause changes in DNA repair compartments. Our study links DNA damage accumulation in aged oocytes, a leading cause of oocyte loss, to cohesin deterioration and changes in the organization, abundance, and response of DNA repair machinery.

A cellular identity crisis? Plasticity changes during aging and rejuvenation

Cellular plasticity in adult multicellular organisms is a protective mechanism that allows certain tissues to regenerate in response to injury. Considering that aging involves exposure to repeated injuries over a lifetime, it is conceivable that cell identity itself is more malleable-and potentially erroneous-with age. In this review, we summarize and critically discuss the available evidence that cells undergo age-related shifts in identity, with an emphasis on those that contribute to age-associated pathologies, including neurodegeneration and cancer. Specifically, we focus on reported instances of programs associated with dedifferentiation, biased differentiation, acquisition of features from alternative lineages, and entry into a preneoplastic state. As some of the most promising approaches to rejuvenate cells reportedly also elicit transient changes to cell identity, we further discuss whether cell state change and rejuvenation can be uncoupled to yield more tractable therapeutic strategies.

N-acetylcysteine supplementation improves endocrine-metabolism profiles and ovulation induction efficacy in polycystic ovary syndrome

BACKGROUND

Polycystic ovary syndrome (PCOS) affects 6-20% of women worldwide, with insulin resistance and hyperinsulinemia occurring in 50-70% of patients. Hyperinsulinemia exacerbates oxidative stress, contributing to PCOS pathogenesis. N-acetylcysteine (NAC) is an antioxidant and insulin sensitizer that shows promise as a therapeutic for PCOS. Our current study aimed to investigate the effects of NAC supplementation on endocrine-metabolic parameters in PCOS mice and its effect on ovulation induction (OI) efficacy in women with PCOS.

METHODS

Female C57BL/6 mice were orally administered letrozole (LE) to induce PCOS and then randomly divided into groups receiving daily oral administration of 160 mg/kg NAC (PCOS + NAC group), 200 mg/kg metformin (PCOS + Met group), or 0.5% carboxymethyl cellulose (drug solvent) (pure PCOS group) for 12 days. Healthy female mice served as pure controls. Estrous cycles were monitored during the intervention. Metabolic and hormone levels, ovarian phenotypes, antioxidant activity in ovarian tissues, and oxidative stress levels in oocytes were assessed post-intervention. Furthermore, a pragmatic, randomized, controlled clinical study was conducted with 230 PCOS women, randomly assigned to the NAC group (1.8 g/day oral NAC, n = 115) or the control group (n = 115). Patients in both groups underwent ≤ 3 cycles of OI with sequential LE and urinary follicle-stimulating hormone (uFSH). Cycle characteristics and pregnancy outcomes were compared between groups.

RESULTS

Similar to metformin, NAC supplementation significantly improved the estrous cycles and ovarian phenotypes of PCOS mice; reduced the LH concentration, LH/FSH ratio, and T level; and increased glucose clearance and insulin sensitivity. Notably, NAC significantly reduced oocyte ROS levels and increased the mitochondrial membrane potential in PCOS mice. Additionally, NAC significantly enhanced enzymatic and nonenzymatic antioxidant activities in PCOS mouse ovaries, whereas metformin had no such effect. In the clinical trial, compared to women in the control group, women receiving NAC had significantly lower average uFSH dosage and duration (p < 0.005) and significantly greater clinical pregnancy rates per OI cycle and cumulative clinical pregnancy rates per patient (p < 0.005).

CONCLUSION

NAC supplementation improved endocrine-metabolic parameters in PCOS mice and significantly enhanced OI efficacy with sequential LE and uFSH in women with PCOS. Therefore, NAC could be a valuable adjuvant in OI for women with PCOS.

A spotlight on factors influencing the in vitro folliculogenesis of isolated preantral follicles

Female fertility preservation via complete in vitro folliculogenesis is still chimerical. Due to many factors affecting the efficiency of isolation and culture of preantral follicles, the improvement of techniques geared to fertility preservation in higher mammals seems to be at an impasse. We need an objective view of the current stand to understand how to progress further. As such, a survey was conducted to analyze the relative distribution of studies performed in ten mammalian species on preantral follicle culture available on PubMed. Using the bovine as a reference model, we explore some factors influencing data variation that contribute to the difficulty in reproducing studies. While years of research have enabled the recapitulation of folliculogenesis from as modest as the early antral follicle stage ex vivo, in vitro preantral folliculogenesis remains elusive. Herein, we revisit the classical evidence that laid the foundations for understanding preantral folliculogenesis and review the length, breadth, and depth of information that the era of big data has currently levied. Moving forward, we recognize the urgency of synthesizing the multi-disciplinary approaches to mimic folliculogenesis in vitro to achieve a translational landscape of infertility at individual and large-scale conservation levels.

The senolytic drug ABT-263 accelerates ovarian aging in older female mice

Previous studies have reported that senolytic drugs can reverse obesity-mediated accumulation of senescent cells in the ovary and protect against cisplatin-induced ovarian injury by removing senescent cells. Early intervention with ABT-263 has been shown to mitigate ovarian aging. However, it remains unknown whether treatment with ABT-263 could rejuvenate the aged ovary in reproductively old females. Therefore, the current study was aimed to investigate whether advanced age intervention with ABT-263 could ameliorate age-related decline in ovarian function. Fourteen 16-month-old mice with a C57/BL6 background were treated with ABT-263 (N = 7) or vehicle (N = 7) for two weeks. Mice were initially treated with ABT-263 (60 mg/kg/d) or vehicle for 7 consecutive days. After a 7-day break, the treatment was repeated for another 7 consecutive days. Six 2-month-old mice with C57BL/6 were used as a young control. The hormonal levels, estrus cycles, ovarian reserve, ovarian cell proliferation and apoptosis, ovarian fibrosis, and steroidogenic gene expression of ovarian stromal cells were evaluated. ABT-263 treatment did not rescue abnormal estrus cycles and sex hormonal levels, or inhibit the formation of multinucleated giant cells and ovarian stromal cell apoptosis in aged ovaries. However, it reduced ovarian fibrosis and preserved the steroidogenic gene expression of ovarian stromal cells in aged ovaries. Importantly, ABT-263 treatment further depleted ovarian follicles in aged mice. In conclusion, ABT-263 treatment accelerated the depletion of ovarian follicles in aged mice, suggesting that senolytic drugs for reproductively old female may adversely affect female fertility.

Single-cell RNA sequencing reveals transcriptomic landscape and potential targets for human testicular ageing

STUDY QUESTION

What is the molecular landscape underlying the functional decline of human testicular ageing?

SUMMARY ANSWER

The present study provides a comprehensive single-cell transcriptomic atlas of testes from young and old humans and offers insights into the molecular mechanisms and potential targets for human testicular ageing.

WHAT IS KNOWN ALREADY

Testicular ageing is known to cause male age-related fertility decline and hypogonadism. Dysfunction of testicular cells has been considered as a key factor for testicular ageing.

STUDY DESIGN, SIZE, DURATION

Human testicular biopsies were collected from three young individuals and three old individuals to perform single-cell RNA sequencing (scRNA-seq). The key results were validated in a larger cohort containing human testicular samples from 10 young donors and 10 old donors.

PARTICIPANTS/MATERIALS, SETTING, METHODS

scRNA-seq was used to identify gene expression signatures for human testicular cells during ageing. Ageing-associated changes of gene expression in spermatogonial stem cells (SSCs) and Leydig cells (LCs) were analysed by gene set enrichment analysis and validated by immunofluorescent and functional assays. Cell-cell communication analysis was performed using CellChat.

MAIN RESULTS AND THE ROLE OF CHANCE

The single-cell transcriptomic landscape of testes from young and old men was surveyed, revealing age-related changes in germline and somatic niche cells. In-depth evaluation of the gene expression dynamics in germ cells revealed that the disruption of the base-excision repair pathway is a prominent characteristic of old SSCs, suggesting that defective DNA repair in SSCs may serve as a potential driver for increased de novo germline mutations with age. Further analysis of ageing-associated transcriptional changes demonstrated that stress-related changes and cytokine pathways accumulate in old somatic cells. Age-related impairment of redox homeostasis in old LCs was identified and pharmacological treatment with antioxidants alleviated this cellular dysfunction of LCs and promoted testosterone production. Lastly, our results revealed that decreased pleiotrophin signalling was a contributing factor for impaired spermatogenesis in testicular ageing.

LARGE SCALE DATA

The scRNA-seq sequencing and processed data reported in this paper were deposited at the Genome Sequence Archive (https://ngdc.cncb.ac.cn/), under the accession number HRA002349.

LIMITATIONS, REASONS FOR CAUTION

Owing to the difficulty in collecting human testis tissue, the sample size was limited. Further in-depth functional and mechanistic studies are warranted in future.

WIDER IMPLICATIONS OF THE FINDINGS

These findings provide a comprehensive understanding of the cell type-specific mechanisms underlying human testicular ageing at a single-cell resolution, and suggest potential therapeutic targets that may be leveraged to address age-related male fertility decline and hypogonadism.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by the National Key Research and Development Program of China (2022YFA1104100), the National Natural Science Foundation of China (32130046, 82171564, 82101669, 82371611, 82371609, 82301796), the Natural Science Foundation of Guangdong Province, China (2022A1515010371), the Major Project of Medical Science and Technology Development Research Center of National Health Planning Commission, China (HDSL202001000), the Open Project of NHC Key Laboratory of Male Reproduction and Genetics (KF202001), the Guangdong Province Regional Joint Fund-Youth Fund Project (2021A1515110921, 2022A1515111201), and the China Postdoctoral Science Foundation (2021M703736). The authors declare no conflict of interest.

Peroxiredoxin 4 deficiency induces accelerated ovarian aging through destroyed proteostasis in granulosa cells

Ovarian aging, a complex and challenging concern within the realm of reproductive medicine, is associated with reduced fertility, menopausal symptoms and long-term health risks. Our previous investigation revealed a correlation between Peroxiredoxin 4 (PRDX4) and human ovarian aging. The purpose of this research was to substantiate the protective role of PRDX4 against ovarian aging and elucidate the underlying molecular mechanism in mice. In this study, a Prdx4-/- mouse model was established and it was observed that the deficiency of PRDX4 led to only an accelerated decline of ovarian function in comparison to wild-type (WT) mice. The impaired ovarian function observed in this study can be attributed to an imbalance in protein homeostasis, an exacerbation of endoplasmic reticulum stress (ER stress), and ultimately an increase in apoptosis of granulosa cells. Furthermore, our research reveals a noteworthy decline in the expression of Follicle-stimulating hormone receptor (FSHR) in aging Prdx4-/- mice, especially the functional trimer, due to impaired disulfide bond formation. Contrarily, the overexpression of PRDX4 facilitated the maintenance of protein homeostasis, mitigated ER stress, and consequently elevated E2 levels in a simulated KGN cell aging model. Additionally, the overexpression of PRDX4 restored the expression of the correct spatial conformation of FSHR, the functional trimer. In summary, our research reveals the significant contribution of PRDX4 in delaying ovarian aging, presenting a novel and promising therapeutic target for ovarian aging from the perspective of endoplasmic reticulum protein homeostasis.

Lycium barbarum berry extract improves female fertility against aging-related oxidative stress in the ovary

Reproductive aging in female mammals is characterized by ovarian senescence, leading to a significant fertility decline. Lycium barbarum berry, or goji berry, is a food and medicine that appears in various formulas for treating infertility in traditional Chinese medicine. We investigated the function of an aqueous extract of Lycium barbarum berry (LB extract) to improve health status, fertility, and offspring development during female aging. Aged female mice were supplemented with LB extract, and its effects on fertility, locomotor activity, and offspring development were assessed. The results demonstrated that LB extract significantly increased pregnancy and live birth rates in naturally aged female mice. It also effectively improved aged animals' locomotor activity. Moreover, LB extract promoted the growth and development of offspring delivered from the aged animals and reduced the offspring's anxiety. During aging, fertility-related hormones gradually decline. However, the decline of anti-Müllerian hormone (AMH) and estradiol (E2) in the serum of aged mice was restored by LB extract supplementation. Immunohistochemical analysis revealed that the levels of oxidation and the inflammatory IL-6 in intra-ovarian cells were reduced by LB extract, while the antioxidant-associated proteins peroxiredoxin 4 (PRDX4) and nuclear factor erythroid 2-related factor 2 (NRF2) were increased. Bioinformatics analysis revealed a decline in egg PRDX4 expression with age across various species. This suggests that the antioxidant function protected by LB extract through PRDX4 may consistently promote fertility enhancement by improving ovarian function across different species. Importantly, LB extract did not induce significant adverse effects on aged female mice and their offspring. These findings highlight the potential of LB as a protective agent against ovarian oxidative stress, which preserves ovarian function and improves fertility rates in naturally senescent females.

Hyperplastic ovarian stromal cells express genes associated to tumor progression: a case study

The current study presents the analysis of stromal cells obtained from an hyperplastic left-ovary of a Holstein cow. Cultured hyperplastic stromal cells displayed a fibroblast-like morphology and ceased proliferation after the 8th passage. The non-cancerous nature of stromal cells was confirmed by in vitro cell proliferation and migration assays. Negligible amounts of E2 were detected in the spent media of cultured stromal cells, which suggests that stromal cells were non-estradiol synthesizing cells. As revealed in immunofluorescence and gene expression analysis, the hyperplastic stromal cells explicitly expressed vimentin in their cytoskeleton. Upon hematoxylin staining, a highly dense population of stromal cells was observed in the stromal tissue of the hyperplastic ovary. To explore genome-wide alterations, mRNA microarray analysis was performed using Affymetrix Bovine Gene 1.0ST Arrays compared to normal ovarian derived stromal cells. The microarray identified 1396 differentially expressed genes, of which 733 were up- and 663 down-regulated in hyperplastic stromal cells. Importantly, asporin (ASPN) and vascular cell adhesion molecule 1 (VCAM1) were among the highly up-regulated genes. Higher expression of ASPN was also confirmed by immunohistochemistry and RT-qPCR analysis. Ingenuity pathway analysis (IPA) identified about 98 significantly enriched (-log (p value ≥ 1.3) canonical pathways, importantly of which the "Sirutin Signaling Pathway" and "Mitochondrial Dysfunction" were highly activated while "Oxidative phosphorylation" was inhibited. Additionally, higher proportion of hyperplastic stromal cells in the S-phase of cell cycle, could be attributed to higher expression levels of cell proliferation genes such as CCND2 and CDK6.

Can ultrasound elastography be useful in the diagnosis of poor ovarian response?

OBJECTIVES

This study aims to compare the elastographic properties of the ovaries of patients with poor ovarian response (POR) with healthy controls by using real-time ultrasound tissue elastography and to investigate the predictive value of ovarian strain ratio (OSR) in the diagnosis of POR.

MATERIALS AND METHODS

A cross-sectional study was conducted among infertility patients. OSR measurements of 46 women diagnosed with POR and 41 healthy controls with male infertility were performed by real-time ultrasound tissue elastography. Ovarian volume, OSR, antral follicle count (AFC), age, body mass index (BMI), anti-mullerian hormone (AMH), follicle stimulating hormone (FSH), and estradiol (E2) values, were compared between the groups. A receiver operating characteristic curve was used to compare the sensitivity and specificity of OSR, AFC, AMH, FSH, and E2 for POR diagnosis.

RESULTS

Patients with POR were significantly older, had a lower duration of infertility, lower AMH, higher FSH, higher E2, lower AFC and ovarian volume (p < 0.01, p = 0.02, p < 0.01, p < 0.01, p < 0.01, p < 0.01, p < 0.01, respectively). The mean OSR of both ovaries was similar between the groups. For the diagnosis of POR, the sensitivity and specificity for AMH were 97.5% and 100%, for AFC were 86.7% and 97.6%; for FSH were 66.7% and 80.5%, for E2 were 53.3% and 90.2%, respectively.

CONCLUSIONS

The significant independent predictors of the POR were AMH, AFC, and FSH, with no additional significant contribution from OSR. However, considering the relationship between POR and ovarian fibrosis, it is recommended to investigate this issue in more comprehensive studies.

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.

SMARTdb: An Integrated Database for Exploring Single-cell Multi-omics Data of Reproductive Medicine

Single-cell multi-omics sequencing has greatly accelerated reproductive research in recent years, and the data are continually growing. However, utilizing these data resources is challenging for wet-lab researchers. A comprehensive platform for exploring single-cell multi-omics data related to reproduction is urgently needed. Here, we introduce the single-cell multi-omics atlas of reproduction (SMARTdb), an integrative and user-friendly platform for exploring molecular dynamics of reproductive development, aging, and disease, which covers multi-omics, multi-species, and multi-stage data. We curated and analyzed single-cell transcriptomic and epigenomic data of over 2.0 million cells from 6 species across the entire lifespan. A series of powerful functionalities are provided, such as "Query gene expression", "DIY expression plot", "DNA methylation plot", and "Epigenome browser". With SMARTdb, we found that the male germ cell-specific expression pattern of RPL39L and RPL10L is conserved between human and other model animals. Moreover, DNA hypomethylation and open chromatin may collectively regulate the specific expression pattern of RPL39L in both male and female germ cells. In summary, SMARTdb is a powerful platform for convenient data mining and gaining novel insights into reproductive development, aging, and disease. SMARTdb is publicly available at https://smart-db.cn.

Building a Human Ovarian Antioxidant ceRNA Network "OvAnOx": A Bioinformatic Perspective for Research on Redox-Related Ovarian Functions and Dysfunctions

The ovary is a major determinant of female reproductive health. Ovarian functions are mainly related to the primordial follicle pool, which is gradually lost with aging. Ovarian aging and reproductive dysfunctions share oxidative stress as a common underlying mechanism. ROS signaling is essential for normal ovarian processes, yet it can contribute to various ovarian disorders when disrupted. Therefore, balance in the redox system is crucial for proper ovarian functions. In the present study, by focusing on mRNAs and ncRNAs described in the ovary and taking into account only validated ncRNA interactions, we built an ovarian antioxidant ceRNA network, named OvAnOx ceRNA, composed of 5 mRNAs (SOD1, SOD2, CAT, PRDX3, GR), 10 miRNAs and 5 lncRNAs (XIST, FGD5-AS1, MALAT1, NEAT1, SNHG1). Our bioinformatic analysis indicated that the components of OvAnOx ceRNA not only contribute to antioxidant defense but are also involved in other ovarian functions. Indeed, antioxidant enzymes encoded by mRNAs of OvAnOx ceRNA operate within a regulatory network that impacts ovarian reserve, follicular dynamics, and oocyte maturation in normal and pathological conditions. The OvAnOx ceRNA network represents a promising tool to unravel the complex dialog between redox potential and ovarian signaling pathways involved in reproductive health, aging, and diseases.

Comparative single-cell transcriptomic analysis across tissues of aging primates reveals specific autologous activation of ZNF281 to mitigate oxidative stress in cornea

Reactive oxygen species (ROS) and oxidative stress accelerate cellular aging, but their impact on different tissues varies. The cornea, known for its robust antioxidant defense systems, is relatively resistant to age-related diseases like cancer. However, the precise mechanisms by which the cornea maintains ROS homeostasis during aging remain unclear. Through comparative single-cell transcriptomic analysis of the cornea and other tissues in young and old nonhuman primates, we identified that a ZNF281 coding transcriptomic program is specifically activated in cornea during aging. Further investigation revealed that ZNF281 forms a positive feedback loop with FOXO3 to sense elevated levels of ROS and mitigate their effects potentially by regulating the mitochondrial respiratory chain and superoxide dismutase (SOD) expression. Importantly, we observed that overexpression of ZNF281 in MSCs prevented cellular senescence. In summary, these findings open up possibilities for understanding tissue-specific aging and developing new therapies targeting ROS damage.

Unraveling the impact of hyperleptinemia on female reproduction: insights from transgenic pig model

BACKGROUND

Infertility is a growing global health concern affecting millions of couples worldwide. Among several factors, an extreme body weight adversely affects reproductive functions. Leptin is a well-known adipokine that serves as an endocrine signal between adiposity and fertility. However, the exact mechanisms underlying the effects of high leptin level on female reproduction remain unclear.

METHODS

Transgenic pigs overexpressing leptin (♀) were produced by backcrossing and screened for leptin overexpression. The growth curve, fat deposition, reproductive performance, apoptosis, serum hormones and cholesterol production, RNA sequencing, and single-nucleus RNA sequencing (snRNA-seq) of the leptin-overexpressing pigs and wild-type group were evaluated.

RESULTS

Transgenic pigs overexpressing leptin (♀) were obtained, which exhibited significantly reduced body weight, body size, and back fat thickness. These pigs manifested a late onset of puberty (330 ± 54.3 vs. 155 ± 14.7 days), irregular estrous behavior characterized by increased inter-estrous interval (29.2 ± 0 vs. 21.3 ± 0.7 days), and more number of matings until pregnancy (at least 3 times). This reproductive impairment in leptin pigs was related to hormonal imbalances characterized by increased levels of FSH, LH, prolactin, E2, P4, and TSH, altered steroidogenesis such as increased levels of serum cholesterol esters along with steroidogenic markers (StAR, CYP19A), and ovarian dysfunctions manifested by neutrophilic infiltration and low expression of caspase-3 positive cells in the ovaries. Moreover, bulk RNA sequencing of the ovaries also revealed neutrophilic infiltration followed by upregulation of inflammation-related genes. Furthermore, snRNA-seq reflected that leptin overexpression triggered immune response, suppressed follicle development and luteinization, resulting in metabolic dysfunction and hormone imbalance in the ovary.

CONCLUSIONS

Low body weight in leptin overexpressing pigs adversely affects the reproductive performance, causing delayed puberty, irregular estrous cycles, and reduced breeding efficiency. This is linked to metabolic imbalances, an increased immune response, and altered ovarian functions. This study provides a theoretical basis for the complex mechanisms underlying leptin, and infertility by employing leptin-overexpressing female pigs.

Rejuvenation of aged oocyte through exposure to young follicular microenvironment

Reproductive aging is a major cause of fertility decline, attributed to decreased oocyte quantity and developmental potential. A possible cause is aging of the surrounding follicular somatic cells that support oocyte growth and development by providing nutrients and regulatory factors. Here, by creating chimeric follicles, whereby an oocyte from one follicle was transplanted into and cultured within another follicle whose native oocyte was removed, we show that young oocytes cultured in aged follicles exhibited impeded meiotic maturation and developmental potential, whereas aged oocytes cultured within young follicles were significantly improved in rates of maturation, blastocyst formation and live birth after in vitro fertilization and embryo implantation. This rejuvenation of aged oocytes was associated with enhanced interaction with somatic cells, transcriptomic and metabolomic remodeling, improved mitochondrial function and higher fidelity of meiotic chromosome segregation. These findings provide the basis for a future follicular somatic cell-based therapy to treat female infertility.

Single-cell sequencing reveals the transcriptional alternations of 17β-estradiol suppressing primordial follicle formation in neonatal mouse ovaries

Estrogen has been implicated in multiple biological processes, but the variation underlying estrogen-mediated primordial follicle (PF) formation remains unclear. Here, we show that 17β-estradiol (E2) treatment of neonatal mice led to the inhibition of PF formation and cell proliferation. Single-cell RNA sequencing (scRNA-seq) revealed that E2 treatment caused significant changes in the transcriptome of oocytes and somatic cells. E2 treatment disrupted the synchronised development of oocytes, pre-granulosa (PG) cells and stromal cells. Mechanistically, E2 treatment disrupted several signalling pathways critical to PF formation, especially down-regulating the Kitl and Smad1/3/4/5/7 expression, reducing the frequency and number of cell communication. In addition, E2 treatment influenced key gene expression, mitochondrial function of oocytes, the recruitment and maintenance of PG cells, the cell proliferation of somatic cells, as well as disordered the ovarian microenvironment. This study not only revealed insights into the regulatory role of estrogen during PF formation, but also filled in knowledge of dramatic changes in perinatal hormones, which are critical for the physiological significance of understanding hormone changes and reproductive protection.

Regulatory Mechanism of Autophagy in Premature Ovarian Failure

Premature ovarian failure (POF) is intricately linked to cellular fates such as senescence, apoptosis, and impaired granulosa cell (GC) differentiation, each of which contributes to ovarian dysfunction and follicular depletion. Autophagy is essential in preventing POF by maintaining cellular homeostasis through the degradation and recycling of damaged organelles and proteins, thereby preserving ovarian function and preventing follicular depletion. Recent studies have revealed that the targeted regulation and disruption of autophagy through various molecular mechanisms ultimately lead to the pathogenesis of POF. In this review, we provide a comprehensive analysis of the disruption in regulatory mechanisms of autophagy contributing to POF. Specifically, we elucidate the molecular mechanisms that can be targeted to restore autophagy homeostasis, offering therapeutic potential for the treatment of POF.

Dynamic changes in cellular atlases and communication patterns within yak ovaries across diverse reproductive states unveiled by single-cell analysis

Yaks (Bos grunniens) exhibit exceptional adaptation to the challenging high-altitude environment of the Qinghai-Tibetan plateau, making them the sole bovine species capable of thriving in such exreme conditions. Investigating the cellular and molecular characteristics of yak ovaries across different reproductive states is crucial for gaining insight into their ovarian functions. Herein, the cellular atlases of yak ovaries in different reproductive states were depicted by single-cell RNA-sequencing (scRNA-seq). The cellular atlases of the ovaries were established by identifying specific gene expression patterns of various cell types, including granulosa cells, theca cells, stromal cells, smooth muscle cells, endothelial cells, glial cell, macrophages, natural killer cells, and proliferating cells. The cellular compositions of the ovaries vary among different reproductive states. Furthermore, the granulosa cells comprise six cell subtypes, while theca cells consist of eight cell subtypes. The granulosa cells and theca cells exhibit distinct biological functions throughout different reproductive states. The two cell types were aligned along their respective pseudotime trajectories. Moreover, a cell-to-cell communication network was constructed among distinct cell types within the ovary, spanning the three reproductive states. Notably, during the estrus period, the granulosa cells demonstrated more prominent interactions with other cell types compared to the remaining reproductive states.

Exploring the heterogeneous targets of metabolic aging at single-cell resolution

Our limited understanding of metabolic aging poses major challenges to comprehending the diverse cellular alterations that contribute to age-related decline, and to devising targeted interventions. This review provides insights into the heterogeneous nature of cellular metabolism during aging and its response to interventions, with a specific focus on cellular heterogeneity and its implications. By synthesizing recent findings using single-cell approaches, we explored the vulnerabilities of distinct cell types and key metabolic pathways. Delving into the cell type-specific alterations underlying the efficacy of systemic interventions, we also discuss the complexity of integrating single-cell data and advocate for leveraging computational tools and artificial intelligence to harness the full potential of these data, develop effective strategies against metabolic aging, and promote healthy aging.

Unique features of KGN granulosa-like tumour cells in the regulation of steroidogenic and antioxidant genes

The ovarian KGN granulosa-like tumour cell line is commonly used as a model for human granulosa cells, especially since it produces steroid hormones. To explore this further, we identified genes that were differentially expressed by KGN cells compared to primary human granulosa cells using three public RNA sequence datasets. Of significance, we identified that the expression of the antioxidant gene TXNRD1 (thioredoxin reductase 1) was extremely high in KGN cells. This is ominous since cytochrome P450 enzymes leak electrons and produce reactive oxygen species during the biosynthesis of steroid hormones. Gene Ontology (GO) analysis identified steroid biosynthetic and cholesterol metabolic processes were more active in primary granulosa cells, whilst in KGN cells, DNA processing, chromosome segregation and kinetochore pathways were more prominent. Expression of cytochrome P450 cholesterol side-chain cleavage (CYP11A1) and cytochrome P450 aromatase (CYP19A1), which are important for the biosynthesis of the steroid hormones progesterone and oestrogen, plus their electron transport chain members (FDXR, FDX1, POR) were measured in cultured KGN cells. KGN cells were treated with 1 mM dibutyryl cAMP (dbcAMP) or 10 μM forskolin, with or without siRNA knockdown of TXNRD1. We also examined expression of antioxidant genes, H2O2 production by Amplex Red assay and DNA damage by γH2Ax staining. Significant increases in CYP11A1 and CYP19A1 were observed by either dbcAMP or forskolin treatments. However, no significant changes in H2O2 levels or DNA damage were found. Knockdown of expression of TXNRD1 by siRNA blocked the stimulation of expression of CYP11A1 and CYP19A1 by dbcAMP. Thus, with TXNRD1 playing such a pivotal role in steroidogenesis in the KGN cells and it being so highly overexpressed, we conclude that KGN cells might not be the most appropriate model of primary granulosa cells for studying the interplay between ovarian steroidogenesis, reactive oxygen species and antioxidants.

Unveiling the role of chronic inflammation in ovarian aging: insights into mechanisms and clinical implications

Ovarian aging, a natural process in women and various other female mammals as they age, is characterized by a decline in ovarian function and fertility due to a reduction in oocyte reserve and quality. This phenomenon is believed to result from a combination of genetic, hormonal, and environmental factors. While these factors collectively contribute to the shaping of ovarian aging, the substantial impact and intricate interplay of chronic inflammation in this process have been somewhat overlooked in discussions. Chronic inflammation, a prolonged and sustained inflammatory response persisting over an extended period, can exert detrimental effects on tissues and organs. This review delves into the novel hallmark of aging-chronic inflammation-to further emphasize the primary characteristics of ovarian aging. It endeavors to explore not only the clinical symptoms but also the underlying mechanisms associated with this complex process. By shining a spotlight on chronic inflammation, the aim is to broaden our understanding of the multifaceted aspects of ovarian aging and its potential clinical implications.

Pterostilbene, a Resveratrol Derivative, Improves Ovary Function by Upregulating Antioxidant Defenses in the Aging Chickens via Increased SIRT1/Nrf2 Expression

Oxidative stress is recognized as a prominent factor contributing to follicular atresia and ovarian aging, which leads to decreased laying performance in hens. Reducing oxidative stress can improve ovarian function and prolong the laying period in poultry. This study investigates the impact of Pterostilbene (PTS), a natural antioxidant, on ovarian oxidative stress in low-laying chickens. Thirty-six Hy-Line White laying chickens were evenly divided into four groups and fed diets containing varying doses of PTS for 15 consecutive days. The results showed that dietary supplementation with PTS significantly increased the laying rate, with the most effective group exhibiting a remarkable 42.7% increase. Furthermore, PTS significantly enhanced the antioxidant capacity of aging laying hens, as evidenced by increased levels of glutathione, glutathione peroxidase, superoxide dismutase, catalase, and total antioxidant capacity in the ovaries, livers, and serum. Subsequent experiments revealed decreased expressions of Bax, Caspase-3, and γ-H2AX, along with an increased expression of BCL-2 in the ovaries and livers of laying hens. PTS supplementation also positively affects fat metabolism by reducing abdominal fat accumulation and promoting fat transfer from the liver to the ovary. To elucidate the mechanism underlying the effects of PTS on ovarian function, a series of in vitro experiments were conducted. These in vitro experiments revealed that PTS pretreatment restored the antioxidant capacity of D-galactose-induced small white follicles by upregulating SIRT1/Nrf2 expression. This protective effect was inhibited by EX-527, a specific inhibitor of SIRT1. These findings suggest that the natural antioxidant PTS has the potential to regulate cell apoptosis and fat metabolism in laying chickens by ameliorating oxidative stress, thereby enhancing laying performance.

Single-nucleus transcriptomics uncovers a geroprotective role of YAP in primate gingival aging

Aging has a profound impact on the gingiva and significantly increases its susceptibility to periodontitis, a worldwide prevalent inflammatory disease. However, a systematic characterization and comprehensive understanding of the regulatory mechanism underlying gingival aging is still lacking. Here, we systematically dissected the phenotypic characteristics of gingiva during aging in primates and constructed the first single-nucleus transcriptomic landscape of gingival aging, by which a panel of cell type-specific signatures were elucidated. Epithelial cells were identified as the most affected cell types by aging in the gingiva. Further analyses pinpointed the crucial role of YAP in epithelial self-renew and homeostasis, which declined during aging in epithelial cells, especially in basal cells. The decline of YAP activity during aging was confirmed in the human gingival tissues, and downregulation of YAP in human primary gingival keratinocytes recapitulated the major phenotypic defects observed in the aged primate gingiva while overexpression of YAP showed rejuvenation effects. Our work provides an in-depth understanding of gingival aging and serves as a rich resource for developing novel strategies to combat aging-associated gingival diseases, with the ultimate goal of advancing periodontal health and promoting healthy aging.

The maintenance of oocytes in the mammalian ovary involves extreme protein longevity

Women are born with all of their oocytes. The oocyte proteome must be maintained with minimal damage throughout the woman's reproductive life, and hence for decades. Here we report that oocyte and ovarian proteostasis involves extreme protein longevity. Mouse ovaries had more extremely long-lived proteins than other tissues, including brain. These long-lived proteins had diverse functions, including in mitochondria, the cytoskeleton, chromatin and proteostasis. The stable proteins resided not only in oocytes but also in long-lived ovarian somatic cells. Our data suggest that mammals increase protein longevity and enhance proteostasis by chaperones and cellular antioxidants to maintain the female germline for long periods. Indeed, protein aggregation in oocytes did not increase with age and proteasome activity did not decay. However, increasing protein longevity cannot fully block female germline senescence. Large-scale proteome profiling of ~8,890 proteins revealed a decline in many long-lived proteins of the proteostasis network in the aging ovary, accompanied by massive proteome remodeling, which eventually leads to female fertility decline.

Iron accumulation in ovarian microenvironment damages the local redox balance and oocyte quality in aging mice

Accumulating oxidative damage is a primary driver of ovarian reserve decline along with aging. However, the mechanism behind the imbalance in reactive oxygen species (ROS) is not yet fully understood. Here we investigated changes in iron metabolism and its relationship with ROS disorder in aging ovaries of mice. We found increased iron content in aging ovaries and oocytes, along with abnormal expression of iron metabolic proteins, including heme oxygenase 1 (HO-1), ferritin heavy chain (FTH), ferritin light chain (FTL), mitochondrial ferritin (FTMT), divalent metal transporter 1 (DMT1), ferroportin1(FPN1), iron regulatory proteins (IRP1 and IRP2) and transferrin receptor 1 (TFR1). Notably, aging oocytes exhibited enhanced ferritinophagy and mitophagy, and consistently, there was an increase in cytosolic Fe2+, elevated lipid peroxidation, mitochondrial dysfunction, and augmented lysosome activity. Additionally, the ovarian expression of p53, p21, p16 and microtubule-associated protein tau (Tau) were also found to be upregulated. These alterations could be phenocopied with in vitro Fe2+ administration in oocytes from 2-month-old mice but were alleviated by deferoxamine (DFO). In vivo application of DFO improved ovarian iron metabolism and redox status in 12-month-old mice, and corrected the alterations in cytosolic Fe2+, ferritinophagy and mitophagy, as well as related degenerative changes in oocytes. Thereby in the whole, DFO delayed the decline in ovarian reserve and significantly increased the number of superovulated oocytes with reduced fragmentation and aneuploidy. Together, our findings suggest that aging-related disturbance in ovarian iron homeostasis contributes to excessive ROS production and that iron chelation may improve ovarian redox status, and efficiently delay the decline in ovarian reserve and oocyte quality in aging mice. These data propose a novel intervention strategy for preserving the ovarian reserve function in elderly women.

Deleterious variants in RNF111 impair female fertility and induce premature ovarian insufficiency in humans and mice

Premature ovarian insufficiency (POI) is a heterogeneous female disorder characterized by the loss of ovarian function before the age of 40. It represents a significant detriment to female fertility. However, the known POI-causative genes currently account for only a fraction of cases. To elucidate the genetic factors underlying POI, we conducted whole-exome sequencing on a family with three fertile POI patients and identified a deleterious missense variant in RNF111. In a subsequent replication study involving 1,030 POI patients, this variant was not only confirmed but also accompanied by the discovery of three additional predicted deleterious RNF111 variants. These variants collectively account for eight cases, representing 0.78% of the study cohort. A further study involving 500 patients with diminished ovarian reserve also identified two additional RNF111 variants. Notably, RNF111 encodes an E3 ubiquitin ligase with a regulatory role in the TGF-β/BMP signaling pathway. Our analysis revealed that RNF111/RNF111 is predominantly expressed in the oocytes of mice, monkeys, and humans. To further investigate the functional implications of RNF111 variants, we generated two mouse models: one with a heterozygous missense mutation (Rnf111+/M) and another with a heterozygous null mutation (Rnf111+/-). Both mouse models exhibited impaired female fertility, characterized by reduced litter sizes and small ovarian reserve. Additionally, RNA-seq and quantitative proteomics analysis unveiled that Rnf111 haploinsufficiency led to dysregulation in female gonad development and negative regulation of the BMP signaling pathway within mouse ovaries. In conclusion, our findings strongly suggest that monoallelic deleterious variants in RNF111 can impair female fertility and induce POI in both humans and mice.

Enhanced prostatic Esr1+ luminal epithelial cells in the absence of SRD5A2

Steroid 5α reductase 2 (SRD5A2) converts testosterone to dihydrotestosterone and is crucial for prostatic development. 5α reductase inhibitors (5ARI) reduce prostate size in benign prostate hyperplasia (BPH) and ameliorate lower urinary tract symptoms secondary to BPH. However, the mechanisms of 5ARI functioning are still not fully understood. Here, we used a Srd5a2-/- mouse model and employed single-cell RNA sequencing to explore the impact of SRD5A2 absence on prostate cellular heterogeneity. Significant alterations in luminal epithelial cell (LE) populations were observed, alongside an increased proportion and proliferative phenotype of estrogen receptor 1 (ESR1)+ LE2 cells, following an SRD5A2-independent ESR1 differentiation trajectory. LE2 cells exhibited enhanced estrogen response gene signatures, suggesting an alternative pathway for prostate growth when SRD5A2 is absent. Human prostate biopsy analysis revealed an inverse correlation between the expressions of SRD5A2 and LE2 markers (ESR1/PKCα), and an inverse correlation between SRD5A2 and the clinical efficiency of 5ARI. These findings provide insights into 5ARI resistance mechanisms and potential alternative therapies for BPH-related lower urinary tract symptoms. © 2024 The Pathological Society of Great Britain and Ireland.

Single-cell analysis of ovarian myeloid cells identifies aging associated changes in macrophages and signaling dynamics

The aging of mammalian ovary is accompanied by an increase in tissue fibrosis and heightened inflammation. Myeloid cells, including macrophages, monocytes, dendritic cells, and neutrophils, play pivotal roles in shaping the ovarian tissue microenvironment and regulating inflammatory responses. However, a comprehensive understanding of the roles of these cells in the ovarian aging process is lacking. To bridge this knowledge gap, we utilized single-cell RNA sequencing (scRNAseq) and flow cytometry analysis to functionally characterize CD45+ CD11b+ myeloid cell populations in young (3 months old) and aged (14-17 months old) murine ovaries. Our dataset unveiled the presence of five ovarian macrophage subsets, including a Cx3cr1 low Cd81 hi subset unique to the aged murine ovary. Most notably, our data revealed significant alterations in ANNEXIN and TGFβ signaling within aged ovarian myeloid cells, which suggest a novel mechanism contributing to the onset and progression of aging-associated inflammation and fibrosis in the ovarian tissue.

Machine learning in time-lapse imaging to differentiate embryos from young vs old mice†

Time-lapse microscopy for embryos is a non-invasive technology used to characterize early embryo development. This study employs time-lapse microscopy and machine learning to elucidate changes in embryonic growth kinetics with maternal aging. We analyzed morphokinetic parameters of embryos from young and aged C57BL6/NJ mice via continuous imaging. Our findings show that aged embryos accelerated through cleavage stages (from 5-cells) to morula compared to younger counterparts, with no significant differences observed in later stages of blastulation. Unsupervised machine learning identified two distinct clusters comprising of embryos from aged or young donors. Moreover, in supervised learning, the extreme gradient boosting algorithm successfully predicted the age-related phenotype with 0.78 accuracy, 0.81 precision, and 0.83 recall following hyperparameter tuning. These results highlight two main scientific insights: maternal aging affects embryonic development pace, and artificial intelligence can differentiate between embryos from aged and young maternal mice by a non-invasive approach. Thus, machine learning can be used to identify morphokinetics phenotypes for further studies. This study has potential for future applications in selecting human embryos for embryo transfer, without or in complement with preimplantation genetic testing.

Honghua Xiaoyao tablet combined with estradiol improves ovarian function in D-galactose-induced aging mice by reducing apoptosis and affecting the release of reproductive hormones: an in vivo study

Context: It is very necessary to delay ovarian aging and prevent age-related health problems. The active ingredient in Honghua Xiaoyao tablet (HHXYT) has the effects of anti-oxidation, anti-inflammation, immune regulation and so on. Objective: To explore the effect and mechanism of Honghua Xiaoyao tablet on aging model mice. Materials and methods: The aging model was established by intraperitoneal injection of D-galactose in model mice. The mice in the HHXYT-L,M,H group were given 0.3 g/kg, 0.6 g/kg and 1.2 g/kg Honghua Xiaoyao tablet suspension respectively, and the HHXYT-M + E2 group was given 0.6 g/kg HHXYT +0.13 mg/kg estradiol valerate for 30 days. In this study, ELISA, HE, Western blot, IH and TUNEL were used. Results: HHXYT + E2 can improve the gonadal index, estrous cycle of aging mice. In HHXYT-M + E2 group, the level of FSH and LH decreased, while E2 and AMH increased significantly. The number of growing follicles in HHXYT-M + E2 group increased, which was better than that of HHXYT alone. Western blot results showed that HHXYT-M + E2 group decreased the expression of Bax, cleaved-Parp, cleaved-Casp-3 and CytC molecules and increased the expression of Bcl-2 in ovarian tissue. FSHR expression decreased in model group and increased in HHXYT group. TUNEL staining showed that the number of apoptotic cells in HHXYT group was reduced, and the HHXYT-M + E2 group was the most significantly. Discussion and conclusion: HHXYT can improve the level of sex hormones and increase the number of growing follicles in aging mice. HHXYT-M + E2 group has the best effect, and its mechanism may be related to reducing ovarian granulosa cell apoptosis.

Single-cell and spatiotemporal profile of ovulation in the mouse ovary

Ovulation is a spatiotemporally coordinated process that involves several tightly controlled events, including oocyte meiotic maturation, cumulus expansion, follicle wall rupture and repair, and ovarian stroma remodeling. To date, no studies have detailed the precise window of ovulation at single-cell resolution. Here, we performed parallel single-cell RNA-seq and spatial transcriptomics on paired mouse ovaries across an ovulation time course to map the spatiotemporal profile of ovarian cell types. We show that major ovarian cell types exhibit time-dependent transcriptional states enriched for distinct functions and have specific localization profiles within the ovary. We also identified gene markers for ovulation-dependent cell states and validated these using orthogonal methods. Finally, we performed cell-cell interaction analyses to identify ligand-receptor pairs that may drive ovulation, revealing previously unappreciated interactions. Taken together, our data provides a rich and comprehensive resource of murine ovulation that can be mined for discovery by the scientific community.

Understanding oocyte ageing

Females are born with a finite and non-renewable reservoir of oocytes, which therefore decline both in number and quality with advancing age. A striking characteristic of oocyte quality is that "ageing" effects manifest whilst women are in their thirties and are therefore still chronologically and physically young. Furthermore, this decline is unrelenting and not modifiable to any great extent by lifestyle or diet. Since oocyte quality is rate-limiting for pregnancy success, as the proportion of good-quality oocytes progressively deteriorate, the chance of successful pregnancy during each 6-12-month period also decreases, becoming exponential after 37 years. Unlike oocyte quality, age-related attrition in the size of the ovarian reservoir is less impactful for natural fertility since only one mature oocyte is typically ovulated per menstrual cycle. In contrast, oocyte numbers are pivotal for in-vitro fertilization success, since larger numbers enable better-quality oocytes to be found and is important for buffering the inefficiencies of the IVF process. The ageing trajectory is accelerated in ~10% of women, so-called premature ovarian ageing, with ~1% of women at the extreme end of this spectrum with loss of ovarian function occurring before 40 years of age, termed premature ovarian insufficiency. The aim of this review was to analyze how ageing impacts the size and quality of the oocyte pool along with emerging interventions for combating low oocyte numbers and improving quality.

Umbilical cord mesenchymal stem cells: A novel approach to intervention of ovarian ageing

Ovarian aging leads to endocrine disorders and systemic degeneration of tissue and organ structure and function, seriously affecting women's physical and mental health. Safe and effective treatments for this condition are lacking. Umbilical cord mesenchymal stem cells (UCMSCs), which have multidirectional differentiation potential, show strong self-renewal, secrete bioactive factors and release exosomes, can undergo homing, colonization, integration and differentiation into supporting and functional cells in tissues and organs through direct manipulation and can also improve the tissue microenvironment through paracrine action, promoting cell division, proliferation and microangiogenesis, inhibiting inflammation and apoptosis, reducing oxidative stress, and mediating two-way immune regulation. These processes activate dormant cells, repaired damaged cells, replace necrotic cells, and regenerate fresh cells, restoring the structure and function of the ageing ovary. Furthermore, with the increasing development of UCMSC research and technology, the therapeutic use of UCMSCs is expected to become an effective means for the treatment of ovarian ageing caused by tissue cell ageing, degeneration, and necrosis.

The impact of maternal age on aneuploidy in oocytes: Reproductive consequences, molecular mechanisms, and future directions

Age-related aneuploidy in human oocytes is a major factor contributing to decreased fertility and adverse reproductive outcomes. As females age, their oocytes are more prone to meiotic chromosome segregation errors, leading primarily to aneuploidy. Elevated aneuploidy rates have also been observed in oocytes from very young, prepubertal conceptions. A key barrier to developing effective treatments for age-related oocyte aneuploidy is our incomplete understanding of the molecular mechanisms involved. The challenge is becoming increasingly critical as more people choose to delay childbearing, a trend that has significant societal implications. In this review, we summarize current knowledge regarding the process of oocyte meiosis and folliculogenesis, highlighting the relationship between age and chromosomal aberrations in oocytes and embryos, and integrate proposed mechanisms of age-related meiotic disturbances across structural, protein, and genomic levels. Our goal is to spur new research directions and therapeutic avenues.