Are sirtuins markers of ovarian aging?

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.

Pyrroloquinoline quinone promotes human mesenchymal stem cell-derived mitochondria to improve premature ovarian insufficiency in mice through the SIRT1/ATM/p53 pathway

BACKGROUND

DNA damage and oxidative stress induced by chemotherapy are important factors in the onset of premature ovarian insufficiency (POI). Studies have shown that mitochondria derived from mesenchymal stem cells (MSC-Mito) are beneficial for age-related diseases, but their efficacy alone is limited. Pyrroloquinoline quinone (PQQ) is a potent antioxidant with significant antiaging and fertility enhancement effects. This study aimed to investigate the therapeutic effect of MSC-Mito in combination with PQQ on POI and the underlying mechanisms involved.

METHODS

A POI animal model was established in C57BL/6J mice by cyclophosphamide and busulfan. The effects of MSC-Mito and PQQ administration on the estrous cycle, ovarian pathological damage, sex hormone secretion, and oxidative stress in mice were evaluated using methods such as vaginal smears and ELISAs. Western blotting and immunohistochemistry were used to assess the expression of SIRT1, PGC-1α, and ATM/p53 pathway proteins in ovarian tissues. A cell model was constructed using KGN cells treated with phosphoramide mustard to investigate DNA damage and apoptosis through comet assays and flow cytometry. SIRT1 siRNA was transfected into KGN cells to further explore the role of the SIRT1/ATM/p53 pathway in combination therapy with MSC-Mito and PQQ for POI.

RESULTS

The combined treatment of MSC-Mito and PQQ significantly restored ovarian function and antioxidant capacity in mice with POI. This treatment also reduced the loss of follicles at various stages, improving the disrupted estrous cycle. In vitro experiments demonstrated that PQQ facilitated the proliferation of MitoTracker-labelled MSC-Mito, synergistically restoring mitochondrial function and inhibiting oxidative stress in combination with MSC-Mito. Both in vivo and in vitro, the combination of MSC-Mito and PQQ increased mitochondrial biogenesis mediated by SIRT1 and PGC-1α while inhibiting the activation of ATM and p53, consequently reducing DNA damage-mediated cell apoptosis. Furthermore, pretreatment of KGN cells with SIRT1 siRNA reversed nearly all the aforementioned changes induced by the combined treatment.

CONCLUSIONS

Our research findings indicate that PQQ facilitates MSC-Mito proliferation and, in combination with MSC-Mito, ameliorates chemotherapy-induced POI through the SIRT1/ATM/p53 signaling pathway.

Role of sirtuins in epigenetic regulation and aging control

Advances in modern healthcare in developed countries make it possible to extend the human lifespan, which is why maintaining active longevity is becoming increasingly important. After the sirtuin (SIRT) protein family was discovered, it started to be considered as a significant regulator of the physiological processes associated with aging. SIRT has deacetylase, deacylase, and ADP-ribosyltransferase activity and modifies a variety of protein substrates, including chromatin components and regulatory proteins. This multifactorial regulatory system affects many processes: cellular metabolism, mitochondrial functions, epigenetic regulation, DNA repair and more. As is expected, the activity of sirtuin proteins affects the manifestation of classic signs of aging in the body, such as cellular senescence, metabolic disorders, mitochondrial dysfunction, genomic instability, and the disruption of epigenetic regulation. Changes in the SIRT activity in human cells can also be considered a marker of aging and are involved in the genesis of various age-dependent disorders. Additionally, experimental data obtained in animal models, as well as data from population genomic studies, suggest a SIRT effect on life expectancy. At the same time, the diversity of sirtuin functions and biochemical substrates makes it extremely complicated to identify cause-and-effect relationships and the direct role of SIRT in controlling the functional state of the body. However, the SIRT influence on the epigenetic regulation of gene expression during the aging process and the development of disorders is one of the most important aspects of maintaining the homeostasis of organs and tissues. The presented review centers on the diversity of SIRT in humans and model animals. In addition to a brief description of the main SIRT enzymatic and biological activity, the review discusses its role in the epigenetic regulation of chromatin structure, including the context of the development of genome instability associated with aging. Studies on the functional connection between SIRT and longevity, as well as its effect on pathological processes associated with aging, such as chronic inflammation, fibrosis, and neuroinflammation, have been critically analyzed.

SIRT6 deficiency causes ovarian hypoplasia by affecting Plod1-related collagen formation

SIRT6 is a key member of the mammalian sirtuin family of conserved nicotinamide adenine dinucleotide (NAD+ )-dependent deacetylases. Previous studies have shown that SIRT6 can regulate metabolism, DNA damage repair and aging. Ovarian aging process usually share similar mechanisms with general aging, which is characterized by decreases in both numbers of ovarian follicles and the quality of oocytes. It is reported that the expression level of SIRT6 was significantly decreased in the ovaries of aged mice, and the level of SIRT6 was positively correlated with ovarian reserve, indicating that SIRT6 may be potential markers of ovarian aging. However, its biological roles in follicular development are still unclear. Here, we explored the effect of SIRT6 on follicular development and found that ovarian development was interrupted in SIRT6 knockout (KO) mice, leading to disruptions of puberty and the estrus cycle, significant decreases in numbers of secondary and antral follicles, and decreased collagen in the ovarian stroma. Plod1, a lysyl hydroxylase that is vital for collagen crosslinking and deposition, was decreased at both the mRNA and protein levels in SIRT6-deficient ovaries and granulosa cells (GCs). Additionally, we found abnormal estrogen levels in both SIRT6 KO mice and SIRT6 KD GCs, accompanied by decreases in the levels of the estrogen biosynthesis genes Cyp11a1, Cyp19a1, Mgarp, and increases in the levels of TNF-α and NF-κB. These results confirmed the effect of SIRT6 on follicular development and revealed a possible molecular mechanism for SIRT6 involvement in follicular development via effects on estrogen biosynthesis and collagen formation.

SIRT3 Regulates Levels of Deacetylated SOD2 to Prevent Oxidative Stress and Mitochondrial Dysfunction During Oocyte Maturation in Pigs

Mammalian oocyte maturation relies on mitochondrial ATP production, but this can lead to damaging reactive oxygen species (ROS). SIRT3, a mitochondrial sirtuin, plays a critical role in regulating mitochondrial redox balance in mouse oocytes under stress; however, its specific roles in porcine oocytes remain unclear. In this study, we utilized the SIRT3 inhibitor 3-TYP to investigate SIRT3's importance in porcine oocyte maturation. Our findings revealed that SIRT3 is expressed in porcine oocytes and its inhibition leads to maturation failure. This was evident through reduced polar body extrusion, arrested cell cycle, as well as disrupted spindle organization and actin distribution. Furthermore, SIRT3 inhibition resulted in a decrease in mitochondrial DNA copy numbers, disruption of mitochondrial membrane potential, and reduced ATP levels, all indicating impaired mitochondrial function in porcine oocytes. Additionally, the primary source of damaged mitochondria was associated with decreased levels of deacetylated superoxide dismutase 2 (SOD2) after SIRT3 inhibition, which led to ROS accumulation and oxidative stress-induced apoptosis. Taken together, our results suggest that SIRT3 regulates the levels of deacetylated SOD2 to maintain redox balance and preserve mitochondrial function during porcine oocyte maturation, with potential implications for improving pig reproduction.

Impact of NAD+ metabolism on ovarian aging

Nicotinamide adenine dinucleotide (NAD+), a crucial coenzyme in cellular redox reactions, is closely associated with age-related functional degeneration and metabolic diseases. NAD exerts direct and indirect influences on many crucial cellular functions, including metabolic pathways, DNA repair, chromatin remodeling, cellular senescence, and immune cell functionality. These cellular processes and functions are essential for maintaining tissue and metabolic homeostasis, as well as healthy aging. Causality has been elucidated between a decline in NAD levels and multiple age-related diseases, which has been confirmed by various strategies aimed at increasing NAD levels in the preclinical setting. Ovarian aging is recognized as a natural process characterized by a decline in follicle number and function, resulting in decreased estrogen production and menopause. In this regard, it is necessary to address the many factors involved in this complicated procedure, which could improve fertility in women of advanced maternal age. Concerning the decrease in NAD+ levels as ovarian aging progresses, promising and exciting results are presented for strategies using NAD+ precursors to promote NAD+ biosynthesis, which could substantially improve oocyte quality and alleviate ovarian aging. Hence, to acquire further insights into NAD+ metabolism and biology, this review aims to probe the factors affecting ovarian aging, the characteristics of NAD+ precursors, and the current research status of NAD+ supplementation in ovarian aging. Specifically, by gaining a comprehensive understanding of these aspects, we are optimistic about the prominent progress that will be made in both research and therapy related to ovarian aging.

Making a good egg: human oocyte health, aging, and in vitro development

Mammalian eggs (oocytes) are formed during fetal life and establish associations with somatic cells to form primordial follicles that create a store of germ cells (the primordial pool). The size of this pool is influenced by key events during the formation of germ cells and by factors that influence the subsequent activation of follicle growth. These regulatory pathways must ensure that the reserve of oocytes within primordial follicles in humans lasts for up to 50 years, yet only approximately 0.1% will ever be ovulated with the rest undergoing degeneration. This review outlines the mechanisms and regulatory pathways that govern the processes of oocyte and follicle formation and later growth, within the ovarian stroma, through to ovulation with particular reference to human oocytes/follicles. In addition, the effects of aging on female reproductive capacity through changes in oocyte number and quality are emphasized, with both the cellular mechanisms and clinical implications discussed. Finally, the details of current developments in culture systems that support all stages of follicle growth to generate mature oocytes in vitro and emerging prospects for making new oocytes from stem cells are outlined.

Nonylphenol Exposure-Induced Oocyte Quality Deterioration Could be Reversed by Boric Acid Supplementation in Rats

In this study, we reported boric acid's protective effects on the quality of nonylphenol (NP)-exposed oocytes. Female rats were classified into 4 groups: control, boric acid, NP, and NP+boric acid. Histopathological studies and immunohistochemical analysis of anti-müllerian hormone (AMH), mechanistic target of rapamycin (mTOR), Sirtuin1 (SIRT1), stem cell factor (SCF) studies were done. The comet assay technique was utilized for DNA damage. The ELISA method was used to determine the concentrations of oxidative stress indicators (SOD, CAT, and MDA), ovarian hormone (INH-B), and inflammation indicators (IL-6 and TNF-α). Boric acid significantly reduced the histopathological alterations and nearly preserved the ovarian reserve. With the restoration of AMH and SCF, boric acid significantly improved the ovarian injury. It downregulated SIRT1 and upregulated the mTOR signaling pathway. It provided DNA damage protection. Ovarian SOD, CAT levels were decreased by boric acid. Boric acid co-administration significantly reduced NP's MDA, IL-6, and TNF-activities. This results imply that boric acid has a protective role in ovarian tissue against NP-mediated infertility.

The Aging Ovary and the Tales Learned Since Fetal Development

BACKGROUND

While the term "aging" implies a process typically associated with later life, the consequences of ovarian aging are evident by the time a woman reaches her forties, and sometimes earlier. This is due to a gradual decline in the quantity and quality of oocytes which occurs over a woman's reproductive lifespan. Indeed, the reproductive potential of the ovary is established even before birth, as the proper formation and assembly of the ovarian germ cell population during fetal life determines the lifetime endowment of oocytes and follicles. In the ovary, sophisticated molecular processes have been identified that regulate the timing of ovarian aging and these are critical to ensuring follicular maintenance.

SUMMARY

The mechanisms thought to contribute to overall aging have been summarized under the term the "hallmarks of aging" and include such processes as DNA damage, mitochondrial dysfunction, telomere attrition, genomic instability, and stem cell exhaustion, among others. Similarly, in the ovary, molecular processes have been identified that regulate the timing of ovarian aging and these are critical to ensuring follicular maintenance. In this review, we outline critical processes involved in ovarian aging, highlight major achievements for treatment of ovarian aging, and discuss ongoing questions and areas of debate.

KEY MESSAGES

Ovarian aging is recognized as what may be a complex process in which age, genetics, environment, and many other factors contribute to the size and depletion of the follicle pool. The putative hallmarks of reproductive aging outlined herein include a diversity of plausible processes contributing to the depletion of the ovarian reserve. More research is needed to clarify if and to what extent these putative regulators do in fact govern follicle and oocyte behavior, and how these signals might be integrated in order to control the overall pattern of ovarian aging.

SIRT6 reduces the symptoms of premature ovarian failure and alleviates oxidative stress and apoptosis in granulosa cells by degrading p66SHC via H3K9AC

CONTEXT

Substantial evidence suggests that ovarian oxidative stress can result in severe ovarian dysfunction.

OBJECTIVE

The purpose of this article is to investigate the potential of SIRT6 in alleviating premature ovarian failure (POF) by inhibiting oxidative stress.

METHODS

To mimic POF, mice were administered daily subcutaneous injections of d-galactose. The levels of E2, FSH, LH, AMH, and progesterone in serum were measured, along with changes in follicles and SIRT6 levels. Mice were treated with the SIRT6 agonist MDL-800, SIRT6 levels, follicles, and aforementioned hormones were reassessed. The effects of MDL-800 on oxidative stress and apoptosis were subsequently identified. Primary granulosa cells were isolated from mice, and the effects of H2O2 and MDL-800 on cell viability, oxidative stress, SIRT6 level, and apoptosis were evaluated. In addition, the regulation of SIRT6 on H3K9AC/p66SHC was verified by examining changes in protein levels, promoter activity, and the reversal effects of p66SHC overexpression.

RESULTS

MDL-800 mitigated hormone fluctuations, reduced follicle depletion in ovarian tissue, and attenuated oxidative stress and apoptosis in mice. In vitro experiments demonstrated that MDL-800 enhanced the resilience of primary granulosa cells against H2O2, as evidenced by increased cell viability and reduced oxidative stress and apoptosis. Furthermore, SIRT6 was found to decrease H3K9AC and p66SHC levels, as well as attenuate p66SHC promoter activity. The protective effects of MDL-800 on cells were reversed upon p66SHC overexpression.

CONCLUSION

In summary, this study highlights that activation of SIRT6 can alleviate POF and reduce oxidative stress by degrading H3K9AC and suppressing p66Shc levels in granulosa cells.

Premature ovarian insufficiency: a review on the role of oxidative stress and the application of antioxidants

Normal levels of reactive oxygen species (ROS) play an important role in regulating follicular growth, angiogenesis and sex hormone synthesis in ovarian tissue. When the balance between ROS and antioxidants is disrupted, however, it can cause serious consequences of oxidative stress (OS), and the quantity and quality of oocytes will decline. Therefore, this review discusses the interrelationship between OS and premature ovarian insufficiency (POI), the potential mechanisms and the methods by which antioxidants can improve POI through controlling the level of OS. We found that OS can mediate changes in genetic materials, signal pathways, transcription factors and ovarian microenvironment, resulting in abnormal apoptosis of ovarian granulosa cells (GCs) and abnormal meiosis as well as decreased mitochondrial Deoxyribonucleic Acid(mtDNA) and other changes, thus accelerating the process of ovarian aging. However, antioxidants, mesenchymal stem cells (MSCs), biological enzymes and other antioxidants can delay the disease process of POI by reducing the ROS level in vivo.

The effect and mechanism of Zigui-Yichong-Fang on improving ovarian reserve in premature ovarian insufficiency by activating SIRT1/Foxo3a pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Zigui-Yichong-Fang (ZGYCF) is a traditional Chinese medicine prescription for the treatment of infertility. It is clinically used to regulate the hormone level of patients, improve ovarian reserve function and increase pregnancy rate. However, the exact mechanism of action is not yet clear.

AIMS OF THE STUDY

This study aims to explore the potential impact of ZGYCF on POI and its mechanism.

MATERIALS AND METHODS

Ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) was used to identify the main compounds of ZGYCF. After confirming the therapeutic effect of ZGYCF on cyclophosphamide-induced POI mice, RNA sequencing (RNA-seq) analysis was carried out to explore the mechanism. Then, the effects of ZGYCF on SIRT1 deacetylated Foxo3a and apoptosis were verified from multiple perspectives by serum hormone level, mRNA validation, histomorphology and protein expression, acetylation modification and other experiments.

RESULTS

ZGYCF can improve the morphological changes of ovarian tissue in POI model mice, reduce the damage of primordial follicles and other follicles at all stages, and protect ovarian reserve. The results of transcriptome sequencing showed that the genes expression of PI3K signal and apoptosis signal pathway were increased in POI model mice; ZGYCF can up-regulate the expression of SIRT1 gene and the expression of estradiol, apoptosis inhibition and other signal pathway genes. In addition, ZGYCF can reduce follicular damage and ovarian cell apoptosis in POI model mice through activating the deacetylation of Foxo3a by SIRT1, and improve ovarian reserve function.

CONCLUSIONS

ZGYCF may improve ovarian reserve function of CTX-induced POI mice by activating SIRT1-mediated deacetylation of Foxo3a, and play a role in the treatment of POI.

Chito-oligosaccharides and macrophages have synergistic effects on improving ovarian stem cells function by regulating inflammatory factors

BACKGROUND

Chronic low-grade inflammation and ovarian germline stem cells (OGSCs) aging are important reasons for the decline of ovarian reserve function, resulting in ovarian aging and infertility. Regulation of chronic inflammation is expected to promote the proliferation and differentiation of OGSCs, which will become a key means for maintaining and remodeling ovarian function. Our previous study demonstrated that Chitosan Oligosaccharides (Cos) promoted the OGSCs proliferation and remodelled the ovarian function through improving the secretion of immune related factors,but the mechanism remains unclear, and the role of macrophages, the important source of various inflammatory mediators in the ovary needs to be further studied. In this study, we used the method of macrophages and OGSCs co-culture to observe the effect and mechanism of Cos on OGSCs, and explore what contribution macrophages give during this process. Our finding provides new drug treatment options and methods for the prevention and treatment of premature ovarian failure and infertility.

METHODS

We used the method of macrophages and OGSCs co-culture to observe the effect and mechanism of Cos on OGSCs, and explore the important contribution of macrophages in it. The immunohistochemical staining was used to locate the OGSCs in the mouse ovary. Immunofluorescent staining, RT-qPCR and ALP staining were used to identify the OGSCs. CCK-8 and western blot were used to evaluate the OGSCs proliferation. β-galactosidase(SA-β-Gal) staining and western blot were used to detect the changing of cyclin-dependent kinase inhibitor 1A(P21), P53, Recombinant Sirtuin 1(SIRT1) and Recombinant Sirtuin 3(SIRT3). The levels of immune factors IL-2, IL-10, TNF-α and TGF-β were explored by using Western blot and ELISA.

RESULTS

We found that Cos promoted OGSCs proliferation in a dose-and time-dependent manner, accompanied by IL-2, TNF-α increase and IL-10, TGF-β decrease. Mouse monocyte-macrophages Leukemia cells(RAW) can also produce the same effect as Cos. When combined with Cos, it can enhance the proliferative effect of Cos in OGSCs, and further increase IL-2, TNF-α and further decrease IL-10, TGF-β. The macrophages can enhance the proliferative effect of Cos in OGSCs is also associated with the further increase in IL-2, TNF-α and the further decrease in IL-10, TGF-β. In this study, we determined that the anti-aging genes SIRT-1 and SIRT-3 protein levels were increased by Cos and RAW respectively, whereas the senescence-associated SA-β-Gal and aging genes P21 and P53 were decreased. Cos and RAW had a protective effect on OGSCs delaying aging. Furthermore, RAW can further decrease the SA-β-Gal and aging genes P21 and P53 by Cos, and further increase SIRT1 and SIRT3 protein levels in OGSCs by Cos.

CONCLUSION

In conclusion, Cos and macrophages have synergistic effects on improving OGSCs function and delaying ovarian aging by regulating inflammatory factors.

Extremely Active Nano-formulation of Resveratrol (XAR™) attenuates and reverses chemotherapy-induced damage in mice ovaries and testes

BACKGROUND

Fertility preservation and restoration in cancer patients/survivors is the need of present times when increased numbers of patients get cured of cancer but face infertility as a serious side effect. Resveratrol has beneficial effects on chemoablated ovaries and testes in mice but has failed to enter the clinics because of extremely poor bioavailability. The present study was undertaken to evaluate the protective and curative effects of Extremely active Resveratrol (XAR™)- a nano-formulation of resveratrol with significantly improved bioavailability- on mouse ovary and testis after chemotherapy. Effects of XAR™ and FSH were compared on stimulation of follicle growth in adult mice ovaries. XAR™ (25 mg/kg) was administered for two days prior to chemotherapy to study the protective effects on the mouse gonads. XAR™ was also administered for 14 days post chemoablation to study the regenerative effects. Besides effect on numbers of primordial and growing follicles and spermatogenesis, the effect of XAR™ was also evaluated on the transcripts specific for ovarian/testicular stem/progenitor/germ cells, their proliferation, differentiation, meiosis, and the antioxidant indices.

RESULTS

Similar to FSH, XAR™ increased the numbers of primordial follicles (PF) as well as growing follicles. It protected the gonads from the adverse effects of chemotherapy and showed the ability to regenerate non-functional, chemoablated gonads. Besides stimulating follicle growth in adult ovaries similar to FSH, XAR™ also protected the testes from the adverse effects of chemotherapy and improved spermatogenesis. This was accompanied by improved anti-oxidant indices.

CONCLUSIONS

The results of the present study potentiate the use of XAR™ in pilot clinical studies to protect gonadal function during oncotherapy and also regenerate non-functional gonads in cancer survivors by improving antioxidant indices and stem cell-based tissue regeneration.

Epigenetics, ovarian cell plasticity, and platelet-rich plasma: Mechanistic theories

Ovarian platelet-rich plasma (PRP) is claimed to restore the fertility potential by improving reserve, an effect perhaps mediated epigenetically by platelet-discharged regulatory elements rather than gonadotropin-activated G-protein coupled receptors, as with stimulated in vitro fertilization (IVF). The finding that fresh activated platelet releasate includes factors able to promote developmental signaling networks necessary to enable cell pluripotency tends to support this theory. The mechanistic uncertainty of intraovarian PRP notwithstanding, at least two other major challenges confront this controversial intervention. The first challenge is to clarify how perimenopausal ovarian function is reset to levels consistent with ovulation. Perhaps a less obvious secondary problem is to confine this renewal such that any induced recalibration of cellular plasticity is kept within acceptable physiologic bounds. Thus, any 'drive' to ovarian rejuvenation must incorporate both accelerator and brake. Ovarian aging may be best viewed as a safeguard against pathologic overgrowth, where senescence operates as an evolved tumor-suppression response. While most ovary cells reach the close of their metabolic life span with low risk for hypertrophy, enhanced lysosomal activity and the proinflammatory 'senescence-associated secretory phenotype' usually offsets this advantage over time. But is recovery of ovarian fitness possible, even if only briefly prior to IVF? Alterations in gap junctions, bio-conductive features, and modulation of gene regulatory networks after PRP use in other tissues are discussed here alongside early data reported from reproductive medicine.

Melatonin enhances autologous adipose-derived stem cells to improve mouse ovarian function in relation to the SIRT6/NF-κB pathway

Background

Premature ovarian insufficiency (POI) is the main cause of female infertility. Adipose-derived stem cells (ADSCs) are ideal candidates for the treatment of POI. However, some deficient biological characteristics of ADSCs limit their utility. This study investigated whether melatonin (MLT)-pretreated autologous ADSCs were superior to ADSCs alone in the treatment of the POI mouse model.

Methods

Autologous ADSCs were isolated and cultured in MLT-containing medium. Surface markers of ADSCs were detected by flow cytometry. To determine the effect of MLT on ADSCs, CCK-8 assay was used to detect ADSCs proliferation and enzyme-linked immunosorbent assay (ELISA) was used to detect the secretion of cytokines. The POI model was established by intraperitoneal injection of cyclophosphamide and busulfan. Then, MLT-pretreated autologous ADSCs were transplanted into mice by intraovarian injection. After 7 days of treatment, ovarian morphology, follicle counts, and sex hormones levels were evaluated by hematoxylin and eosin (H&E) staining and ELISA, and the recovery of fertility was also observed. The expressions of SIRT6 and NF-κB were detected by immunohistochemical (IHC) staining and quantitative real-time polymerase chain reaction (qRT-PCR).

Results

Flow cytometry showed that autologous ADSCs expressed CD90 (99.7%) and CD29 (97.5%). MLT can not only promote the proliferation of ADSCs but also boost their secretory function, especially when ADSCs were pretreated with 5 µM MLT for 3 days, improving the interference effect. After transplantation of autologous ADSCs pretreated with 5 µM MLT, the serum hormone levels and reproductive function were significantly recovered, and the mean counts of primordial follicle increased. At the same time, the expression of SIRT6 was remarkably increased and the expression of NF-κB was significantly decreased in this group.

Conclusions

MLT enhances several effects of ADSCs in restoring hormone levels, mean primordial follicle counts, and reproductive capacity in POI mice. Meanwhile, our results suggest that the SIRT6/NF-κB signal pathway may be the potential therapeutic mechanism for ADSCs to treat POI.

SIRT6 Widely Regulates Aging, Immunity, and Cancer

SIRT6 is a member of the Sir2-like family in mammals. Recent structural and biochemical studies have characterized SIRT6 as having deacetylation, defatty-acylation, and mono-ADP-ribosylation activities, which determine its important regulatory roles during physiological and pathological processes. This review focuses mainly on the regulatory functions of SIRT6 in aging, cancer, and, especially, immunity. Particular attention is paid to studies illustrating the critical role of SIRT6 in the regulation of immune cells from the viewpoints of immunesenescence, immunometabolism, and tumor immunology. Owing to its role in regulating the function of the immune system, SIRT6 can be considered to be a potential therapeutic target for the treatment of diseases.

Sirt6 reprograms myofibers to oxidative type through CREB-dependent Sox6 suppression

Expanding the exercise capacity of skeletal muscle is an emerging strategy to combat obesity-related metabolic diseases and this can be achieved by shifting skeletal muscle fibers toward slow-twitch oxidative type. Here, we report that Sirt6, an anti-aging histone deacetylase, is critical in regulating myofiber configuration toward oxidative type and that Sirt6 activator can be an exercise mimetic. Genetic inactivation of Sirt6 in skeletal muscle reduced while its transgenic overexpression increased mitochondrial oxidative capacity and exercise performance in mice. Mechanistically, we show that Sirt6 downregulated Sox6, a key repressor of slow fiber specific gene, by increasing the transcription of CREB. Sirt6 expression is elevated in chronically exercised humans, and mice treated with an activator of Sirt6 showed an increase in exercise endurance as compared to exercise-trained controls. Thus, the current study identifies Sirt6 as a molecular target for reprogramming myofiber composition toward the oxidative type and for improving muscle performance.

Decrease in ovarian reserve through the inhibition of SIRT1-mediated oxidative phosphorylation

OBJECTIVE

To establish an oxidative stress-induced model of premature ovarian insufficiency (POI) and to explore the effect of SIRT1 and mitochondrial oxidative phosphorylation on the ovarian reserve.

METHODS

Mice were treated with intraperitoneal injections of 3-nitropropionic acid (3-NPA) at different doses and for different time periods to induce a model of POI. Subsequently, the efficiency of each regimen was evaluated. The expression of SIRT1 in ovarian tissue was examined. Then, SIRT1 was knocked down in human luteinized granulosa cells (GCs), and its function and related receptor and gene expression were examined. Finally, a SIRT1 antagonist and agonist were used to explore the effects of SIRT1 on ovarian function in vivo and on the change in mitochondrial oxidative phosphorylation complexes (OXPHOS).

RESULTS

Decreases in ovarian reserve were successfully induced through the intraperitoneal injection of 40 mg/kg 3-NPA for 3 weeks, and SIRT1 was down-regulated in the model group. The knockdown of SIRT1 impaired the estrogen synthesis capacity of human GCs and decreased the expression of related genes. 3-NPA and SIRT1 antagonist Ex-527 decreased ovarian function and inhibited OXPHOS. In contrast, the SIRT1 agonist resveratrol promoted the recovery of ovarian function in the model group and improved OXPHOS. Additionally, P53, CASPASE 3, and BAX were down-regulated and BCL2 was up-regulated in the 3-NPA and Ex-527 groups; opposite trends were observed after resveratrol treatment.

CONCLUSIONS

The intraperitoneal injection of 40 mg/kg 3-NPA for 3 weeks could effectively induce POI. The increase in oxidative stress inhibited SRIT1 and mitochondrial oxidative phosphorylation, inducing follicular apoptosis.

Protective effect of small peptides from Periplaneta americana on cyclophosphamide-induced premature ovarian failure

AIM

To investigate the protective effect of small peptides from Periplaneta americana (SPPA) on cyclophosphamide (CP)-induced premature ovarian failure (POF) in mice. Silent mating type information regulation 2 homolog 1 (SIRT1) /tumor-associated protein 53 (p53) signaling pathway plays an important role in delaying POF. Hematopoietic progenitor cell antigen (CD34) reflects ovarian aging from the side. However, whether SPPA inhibits POF in mice by influencing the SIRT1/p53 pathway and CD34 expression remains to be studied.

METHODS

Forty female Kun Ming (KM) mice were divided into four groups: a control group (normal saline, n = 10), POF model group (160 mg/kg CP, n = 10), SPPA low-dosage group (160 mg/kg CP + 100 mg/kg SPPA, n = 10), and SPPA high-dosage group (160 mg/kg CP + 200 mg/kg SPPA, n = 10). CP administration route is intraperitoneal injection, and SPPA administration route is intragastric. Eyeball enucleation blood samples and the ovaries of mice were collected by midline laparatomy and oopherectomy, and the malondialdehyde (MDA), nitric oxide (NO), superoxide dismutase (SOD), follicle-stimulating hormone (FSH), and anti-Müllerian hormone (AMH) concentrations were tested. Immunohistochemical tests for the expressions of SIRT1, p53, and CD34 were carried out. Finally, ovarian mRNA levels of SIRT1 and p53 were detected with real-time fluorescence quantification PCR (qRT-PCR).

RESULTS

A mouse model of POF was generated using 160 mg/kg of CP. Compared with POF group, we found that plasma NO, MDA, and FSH decreased, while AMH and SOD increased in the SPPA low-dose group. Compared with the POF group, the SPPA low- and high-dosage groups achieved significant growth in the number of primordial, primary, and total number of healthy follicles at all levels, but sharp reductions in the number of atretic follicles. In addition, we found downregulated protein and mRNA expression of SIRT1, and upregulated that of p53 were observed in ovarian tissues of treated mice with POF, in immunohistochemistry experiments and qPCR experiments. In contrast, high protein and mRNA expression of SIRT1, and low that of p53 were observed in SPPA treatment groups. And the results of CD34 protein expression were consistent with that of SIRT1.

CONCLUSION

In total, SPPA significantly inhibited POF caused by CP in mice via activation of the SIRT1/p53 signaling pathway in the mouse ovary.

Photoperiodic modulation of ovarian metabolic, survival, proliferation and gap junction markers in adult golden hamster, Mesocricetus auratus

Female reproductive physiology is greatly dependent on tight regulation of metabolic and survival factors. Photoperiod regulates female reproductive rhythms but very less information exists explaining whether photoperiod could modulate thyroid hormone homeostasis, metabolic/energy parameters along with survival, proliferation and gap junction proteins in the ovary of a long-day breeder, Mesocricetus auratus. Adult female hamsters were exposed to different photoperiodic regimes i.e., critical photoperiod (CP; 12.5L:11.5D), short photoperiod (SP; 8L:16D) and long photoperiod (LP; 16L:8D) for 12 weeks. LP upregulated thyroidal and gonadal activity as apparent by histoarchitecture, thyroid hormone profile [triiodothyronine (T3), thyroxin (T4) and thyroid stimulating hormone (TSH)], luteinizing hormone (LH), follicle stimulating hormone (FSH), estradiol (E2) and progesterone (P4) levels when compared with SP exposed hamsters. Further, LP increased thyroid hormone receptor-α/deiodinase-2 (TRα/Dio-2), estrogen receptor-α (ERα)/aromatase and insulin receptor/glucose transporter-4 (IR/GLUT-4) expressions in ovary. Interestingly, ovarian sirtuin-1 (SIRT-1) expression was also upregulated under LP condition along with cell proliferation (proliferating cell nuclear antigen or PCNA), survival (B cell lymphoma-2 or Bcl-2) and gap junction (connexin-43) markers when compared to SP exposed hamsters. We also noted elevated levels of circulatory leptin, insulin along with melatonin and its receptor (MT-1) in ovary under SP condition. Thus, we suggest that photoperiod plays a vital role in regulation of thyroid and reproductive hormone homeostasis along with key metabolic and survival markers in the ovary of adult golden hamsters, M. auratus providing further insight into the regulation of female reproductive seasonality in a long-day breeder.

Reproductive Longevity and Aging: Geroscience Approaches to Maintain Long-Term Ovarian Fitness

Increases in delayed childbearing worldwide have elicited the need for a better understanding of the biological underpinnings and implications of age-related infertility. In women 35 years and older the incidences of infertility, aneuploidy, and birth defects dramatically increase. These outcomes are a result of age-related declines in both ovarian reserve and oocyte quality. In addition to waning reproductive function, the decline in estrogen secretion at menopause contributes to multisystem aging and the initiation of frailty. Both reproductive and hormonal ovarian function are limited by the primordial follicle pool, which is established in utero and declines irreversibly until menopause. Because ovarian function is dependent on the primordial follicle pool, an understanding of the mechanisms that regulate follicular growth and maintenance of the primordial follicle pool is critical for the development of interventions to prolong the reproductive life span. Multiple pathways related to aging and nutrient-sensing converge in the mammalian ovary to regulate quiescence or activation of primordial follicles. The PI3K/PTEN/AKT/FOXO3 and associated TSC/mTOR pathways are central to the regulation of the primordial follicle pool; however, aging-associated systems such as the insulin-like growth factor-1/growth hormone pathway, and transsulfuration/hydrogen sulfide pathways may also play a role. Additionally, sirtuins aid in maintaining developmental metabolic competence and chromosomal integrity of the oocyte. Here we review the pathways that regulate ovarian reserve and oocyte quality, and discuss geroscience interventions that leverage our understanding of these pathways to promote reproductive longevity.

Mitochondrial Sirtuins in Reproduction

Mitochondria act as hubs of numerous metabolic pathways. Mitochondrial dysfunctions contribute to altering the redox balance and predispose to aging and metabolic alterations. The sirtuin family is composed of seven members and three of them, SIRT3-5, are housed in mitochondria. They catalyze NAD+-dependent deacylation and the ADP-ribosylation of mitochondrial proteins, thereby modulating gene expression and activities of enzymes involved in oxidative metabolism and stress responses. In this context, mitochondrial sirtuins (mtSIRTs) act in synergistic or antagonistic manners to protect from aging and aging-related metabolic abnormalities. In this review, we focus on the role of mtSIRTs in the biological competence of reproductive cells, organs, and embryos. Most studies are focused on SIRT3 in female reproduction, providing evidence that SIRT3 improves the competence of oocytes in humans and animal models. Moreover, SIRT3 protects oocytes, early embryos, and ovaries against stress conditions. The relationship between derangement of SIRT3 signaling and the imbalance of ROS and antioxidant defenses in testes has also been demonstrated. Very little is known about SIRT4 and SIRT5 functions in the reproductive system. The final goal of this work is to understand whether sirtuin-based signaling may be taken into account as potential targets for therapeutic applications in female and male infertility.

NAD+ Repletion Rescues Female Fertility during Reproductive Aging

Reproductive aging in female mammals is an irreversible process associated with declining oocyte quality, which is the rate-limiting factor to fertility. Here, we show that this loss of oocyte quality with age accompanies declining levels of the prominent metabolic cofactor nicotinamide adenine dinucleotide (NAD⁺). Treatment with the NAD⁺ metabolic precursor nicotinamide mononucleotide (NMN) rejuvenates oocyte quality in aged animals, leading to restoration in fertility, and this can be recapitulated by transgenic overexpression of the NAD⁺-dependent deacylase SIRT2, though deletion of this enzyme does not impair oocyte quality. These benefits of NMN extend to the developing embryo, where supplementation reverses the adverse effect of maternal age on developmental milestones. These findings suggest that late-life restoration of NAD⁺ levels represents an opportunity to rescue female reproductive function in mammals.

Declining oocyte quality is considered an irreversible feature of aging and is rate limiting for human fertility. Bertoldo et al. show that reversing an age-dependent decline in NAD(P)H restores oocyte quality, embryo development, and functional fertility in aged mice. These findings may be relevant to reproductive medicine.

Developmental programming: intrauterine caloric restriction promotes upregulation of mitochondrial sirtuin with mild effects on oxidative parameters in the ovaries and testes of offspring

According to the developmental origins of health and disease (DOHaD) hypothesis, changes in the maternal environment are known to reprogram the metabolic response of offspring. Known for its redox modulation, caloric restriction extends the lifespan of some species, which contributes to diminished cellular damage. Little is known about the effects of gestational caloric restriction, in terms of antioxidant parameters and molecular mechanisms of action, on the reproductive organs of offspring. This study assessed the effects of moderate (20%) caloric restriction on redox status parameters, molecular expression of sirtuin (SIRT) 1 and SIRT3 and histopathological markers in the ovaries and testes of adult rats that were subjected to gestational caloric restriction. Although enzyme activity was increased, ovaries from female pups contained high levels of oxidants, whereas testes from male pups had decreased antioxidant enzyme defences, as evidenced by diminished glyoxalase I activity and reduced glutathione content. Expression of SIRT3, a deacetylase enzyme related to cellular bioenergetics, was increased in both ovaries and testes. Previous studies have suggested that, in ovaries, diminished antioxidant metabolism can lead to premature ovarian failure. Unfortunately, there is little information regarding the redox profile in the testis. This study is the first to assess the redox network in both ovaries and testes, suggesting that, although intrauterine caloric restriction improves molecular mechanisms, it has a negative effect on the antioxidant network and redox status of reproductive organs of young adult rats.

Value of serum and follicular fluid sirtuin (SIRT)1 and SIRT2 protein levels in predicting the outcome of assisted reproduction

Background

To explore whether serum and follicular fluid (FF), sirtuin 1 (SIRT1), and SIRT2 could predict the outcome of assisted reproduction.

Methods

All patients underwent in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI) for the first time in the Reproductive Medicine Center of the First Affiliated Hospital of Zhejiang University Medical College from March 2018 to December 2018. According to cumulative clinical pregnancy outcomes, the patients were divided into a pregnancy group and non-pregnancy group. We measured the serum levels of SIRT1, SIRT2, anti-Müllerian hormone (AMH), follicle-stimulating hormone (FSH), luteinizing hormone (LH), and estradiol (E2) from the second to the fifth day of menstruation, and the levels of SIRT1 and SIRT2 in serum and FF on the day of human chorionic gonadotropin (HCG) injection and oocyte retrieval.

Results

A total of 125 patients met the inclusion criteria. The pregnancy group comprised 56 cases and non-pregnancy group 69 cases. There were significant differences in basal level SIRT2 (bSIRT2), AMH, antral follicle count (AFC), number of oocytes obtained, number of mature eggs, number of fertilized eggs, number of excellent embryos, number of blastocyst formations, and number of transferred high-quality embryos between the two groups. The area under the curve (AUC) values of bSIRT2, AFC, AMH, and age were significantly different from those under the opportunity reference line (P<0.05). In the subsequent correlation analysis, FFSIRT2, and HCG day serum SIRT2 were negatively correlated with age (r=−0.35, r=−0.19), and positively correlated with AFC (r=0.2, r=0.02). Serum SIRT1 on HCG day was negatively correlated with the number of blastocysts and the number of frozen embryos (r=−0.18, r=−0.21). Levels of FF SIRT1 and FF SIRT2 were significantly lower than those in serum SIRT1 and SIRT2, and there was no significant difference in serum SIRT1 and SIRT2 before and after ovulation promotion.

Conclusions

The results suggest that bSIRT2 has significant statistical significance in predicting the cumulative number of pregnancies. When combined with AMH, AFC, and age, bSIRT2 can predict the cumulative pregnancy outcome. In addition, the level of serum SIRT1 and SIRT2 were not affected by ovulation promotion.

Caloric restriction in female reproduction: is it beneficial or detrimental?

Caloric restriction (CR), an energy-restricted intervention with undernutrition instead of malnutrition, is widely known to prolong lifespan and protect against the age-related deteriorations. Recently it is found that CR significantly affects female reproduction via hypothalamic (corticotropin releasing hormone, neuropeptide Y, agouti-related peptide) and peripheral (leptin, ghrelin, insulin, insulin-like growth factor) mediators, which can regulate the energy homeostasis. Although CR reduces the fertility in female mammals, it exerts positive effects like preserving reproductive capacity. In this review, we aim to discuss the comprehensive effects of CR on the central hypothalamus-pituitary-gonad axis and peripheral ovary and uterus. In addition, we emphasize the influence of CR during pregnancy and highlight the relationship between CR and reproductive-associated diseases. Fully understanding and analyzing the effects of CR on the female reproduction could provide better strategies for the management and prevention of female reproductive dysfunctions.

The evolutionary ecology of age at natural menopause: implications for public health

Evolutionary perspectives on menopause have focused on explaining why early reproductive cessation in females has emerged and why it is rare throughout the animal kingdom, but less attention has been given to exploring patterns of diversity in age at natural menopause. In this paper, we aim to generate new hypotheses for understanding human patterns of diversity in this trait, defined as age at final menstrual period. To do so, we develop a multilevel, interdisciplinary framework, combining proximate, physiological understandings of ovarian ageing with ultimate, evolutionary perspectives on ageing. We begin by reviewing known patterns of diversity in age at natural menopause in humans, and highlight issues in how menopause is currently defined and measured. Second, we consider together ultimate explanations of menopause timing and proximate understandings of ovarian ageing. We find that ovarian ageing is highly constrained by ageing of the follicle - the somatic structure containing the oocyte - suggesting that menopause timing might be best understood as a by-product of ageing rather than a facultative adaptation. Third, we investigate whether the determinants of somatic senescence also underpin menopause timing. We show that diversity in age at menopause can be, at least partly, explained by the genetic, ecological and life-history determinants of somatic ageing. The public health implications of rethinking menopause as the by-product rather than the catalyst of biological ageing are discussed.

Inhibition of visfatin/NAMPT affects ovarian proliferation, apoptosis, and steroidogenesis in pre-pubertal mice ovary

Pubertal ovarian function might be dependent on the factors present in the pre-pubertal stages. Visfatin regulates ovarian steroidogenesis in adult. To date, no study has investigated the role of visfatin either in pre-pubertal or pubertal mice ovary. Thus, we investigated the role of visfatin in pre-pubertal mice ovary in relation to steroidogenesis and proliferation and apoptosis in vitro by inhibiting the endogenous visfatin by a specific inhibitor, FK866. Inhibition of visfatin increased the estrogen secretion and also up-regulated the expression of CYP11A1, 17βHSD and CYP19A1 in mice ovary. Furthermore, active caspase3 was up-regulated along with the down-regulation of BAX and BCL2 in the pre-pubertal ovary after visfatin inhibition. The expression of GCNA, PCNA, and BrdU labeling was also decreased by FK866 treatment. These results suggest that visfatin inhibits steroidogenesis, increases proliferation, and suppresses apoptosis in the pre-pubertal mice ovary. So, visfatin is a new regulator of ovary function in pre-pubertal mice.

MicroRNA-572/hMOF/Sirt6 regulates the progression of ovarian cancer

Human males absent on the first (hMOF) is a histone acetyltransferase (HAT) and is involved in the pathogenesis of various cancers. This article aimed to reveal the potential mechanism of the miR-572/hMOF/Sirt6 axis in ovarian cancer (OC). In this study, we found that the mRNA and protein levels of hMOF and Sirt6 were abnormally down-regulated in OC tissues and cells. Further study indicated that the overexpression of hMOF increased the level of H4 histone acetylation in the Sirt6 promoter region and enhanced the ability of hMOF to bind to the Sirt6 promoter in OC cells, and repressed the proliferation of SKOV3 cells and promoted the apoptosis of SKOV3 cells via up-regulating Sirt6. Moreover, it was found that miR-572 negatively regulated hMOF luciferase activity. After the transfection of miR-572 inhibitor into SKOV3 cells, the cell proliferation was significantly repressed, while this repression was reversed after the transfection of shRNA-hMOF. Besides, the overexpression of hMOF could significantly inhibit the growth of tumors. Overall, our findings uncovered a novel regulatory pattern of hMOF in OC progression and provided new insights for relieving OC.

Expression of sirtuins in ovarian follicles of postnatal mice

Mammalian ovarian follicular development is an intricate, elaborate, and well-organized phenomenon regulated by various signaling pathways; however, the underlying mechanism remains unclear. Mammalian sirtuins (sirtuin 1 to sirtuin 7) are a group of NAD⁺ -dependent deacetylases implicated in various physiological processes including cell proliferation, apoptosis, cell cycle progression, and insulin signaling. Mammalian ovarian sirtuins have been studied using adult and aged bovine, porcine, and murine models. However, limited information is available regarding their precise expression patterns and the localization of follicle development in mice. This study aimed to assess the dynamic expression and localization of all seven sirtuins in early postnatal mouse ovaries through real-time polymerase chain reaction analysis and immunohistochemistry, respectively. During postnatal ovarian follicle development, sirtuin 1, sirtuin 4, and sirtuin 6 were downregulated compared with those in 1-day postnatal mouse ovaries (p < .05), indicating that these three sirtuin genes may be markers of follicular development. Combining their localization in granulosa cells through immunohistochemical studies, sirtuin 1, sirtuin 4, and sirtuin 6 are suggested to play negative regulatory roles in mammal ovarian follicular granulosa cell development. Furthermore, we found that sirtuin 2 (p < .05) and sirtuin 7 (p < .05) mRNA were constantly upregulated relative to sirtuin 1, although limited information is available regarding sirtuin 7. Among all sirtuins in mouse ovaries, sirtuin 1 was relatively and steadily downregulated. Upon sirtuin 1 overexpression in 1-day postnatal mouse ovaries via sirtuin 1-harboring adenoviruses in vitro, the emergence of primary follicles was delayed, as was the emergence of secondary follicles in 4-day postnatal ovaries. Further studies on KGN cell lines reported that interfering with sirtuin 1 expression in granulosa cell significantly affected granulosa cell proliferation and the expression of mitochondrial genes. This study presents the first systemic analysis of dynamic patterns of sirtuin family expression in early postnatal mice ovaries, laying the foundation for further studies on less discussed sirtuin subtypes, such as sirtuin 5 and sirtuin 7.

Sirt1 sustains female fertility by slowing age-related decline in oocyte quality required for post-fertilization embryo development

The NAD⁺‐dependent sirtuin deacetylase, Sirt1, regulates key transcription factors strongly implicated in ageing and lifespan. Due to potential confounding effects secondary to loss of Sirt1 function from the soma in existing whole‐animal mutants, the in vivo role of Sirt1 in oocytes (oocyte‐Sirt1) for female fertility remains unknown. We deleted Sirt1 specifically in growing oocytes and study how loss of oocyte‐Sirt1 affects a comprehensive range of female reproductive parameters including ovarian follicular reservoir, oocyte maturation, oocyte mitochondrial abundance, oxidative stress, fertilization, embryo development and fertility during ageing. Surprisingly, eliminating this key sirtuin from growing oocytes has no effect in young females. During a 10‐month‐long breeding trial, however, we find that 50% of females lacking oocyte‐Sirt1 become prematurely sterile between 9 and 11 months of age when 100% of wild‐type females remain fertile. This is not due to an accelerated age‐related decline in oocyte numbers in the absence of oocyte‐Sirt1 but to reduced oocyte developmental competence or quality. Compromised oocyte quality does not impact in vivo oocyte maturation or fertilization but leads to increased oxidative stress in preimplantation embryos that inhibits cleavage divisions. Our data suggest that defects emerge in aged females lacking oocyte‐Sirt1 due to concurrent age‐related changes such as reduced NAD⁺ and sirtuin expression levels, which compromise compensatory mechanisms that can cover for Sirt1 loss in younger oocytes. In contrast to evidence that increasing Sirt1 activity delays ageing, our data provide some of the only in vivo evidence that loss of Sirt1 induces premature ageing.

Metformin prevents murine ovarian aging

A number of studies have shown that metformin can delay aging process and extend healthy lifespan in animals. However, its role in female reproductive lifespan is unclear. This study was aimed to explore the potential anti-aging effect of metformin on the ovary and its possible mechanisms. Female C57BL/6 mice of 27-week old were divided into two groups, the control group (CON) and metformin-treated group (MET). CON mice were fed ad libitum, while MET mice were fed on chows supplied with 100mg/kg metformin for half a year. Ovarian reserve and function were assessed by ovarian follicle counts, estrous cycle and sex hormones levels. The expressions of oxidized metabolites, such as 8-hydroxy-2´-deoxyguanosine (8-OHdG), 4-hydroxynonenal (4-HNE), nitrotyrosine (NTY), and ovarian aging associated proteins P16, SIRT1, p-rpS6 and Bcl2 were examined. The MET mice exhibited increased level of serum E2 hormone and higher percentage of regular estrous cycles after 6 months' feeding, compared to the CON mice. The amount of primordial and primary follicles and the expression of SIRT1 were significantly increased, but the levels of P16, 8-OHdG, 4-HNE and p-rpS6 were decreased in the MET mice. These results indicate that metformin can delay ovarian aging process, probably by inducing the expression of SIRT1 and reducing the oxidative damage.

The roles of cirRNA in the development of germ cells

Circular RNA (CircRNA), a type of endogenous non-coding RNAs (ncRNAs), is generally generated from precursor mRNA (pre-mRNA) by canonical splicing and head-to-tail back splicing. The structure without a polyA tail renders circRNA highly insensitive to ribonuclease. Simultaneously, the distribution of circRNAs is tissue and developmental stage-specific. There are five potential biological functions of circRNAs: 1) promote transcription of their parental genes; 2) function as a miRNA sponge; 3) RNA binding protein (RBP) sponge; 4) encode protein; 5) act as an mRNA trap. Recently, circRNA has attracted attention because studies have shown that circRNAs are associated with follicular development, ovarian senescence, spermatogenesis, and germ cell development process, suggesting that circRNAs may function in germ cells regulation. The investigation of circRNAs in germ cells will provide an excellent opportunity to understand its potential molecular basis, and potentially improving reproduction status in human. In this article, the relationship between circRNA and germ cell development will be discussed.

Exendin-4 exhibits a tumour suppressor effect in SKOVR-3 and OVACR-3 ovarian cancer cells lines by the activation of SIRT1 and inhibition of NF-κB

This study investigated if EX-527 has an anti-tumour effect in SKOV-3 and OVCAR-3 ovarian cancer (OC) cell lines and if this effect involves the SIRT1/NF-κB axis. Cells were cultured in the presence or absence of EX-527, a selective SIRT-1 inhibitor. Exendin-4 significantly induced cell death in both cell lines and inhibited cell migration and invasion. Also, it decreased protein levels of Bcl-2, MMP-9, and ICAM-1 and increased those of Bax, cyclin D1 and cleaved caspase-3. Mechanistically, Exendin-4 increased the activity and nuclear accumulation of SIRT1 and decreased nuclear levels of NF-κB p65; acetylated levels of NF-κB p65, and cytoplasmic levels of p-IKKα and p-IκBα. EX-527 partially ameliorated the effect of Exendin-4 on cell death, migration, and invasion, as well as on the expression of Bcl-2, MMP-9, Bax, cleaved caspase-3 and ICAM-1. In addition, EX-527 did not affect the levels of nuclear p65 and p-p65 (Ser536); p-IκBα (Ser32) and p-IKKαβ. In conclusion, Exendin-4 can suppress OC by inhibiting NF-kB through SIRT1 dependent and independent mechanisms.

Identification and characterization of human ovary-derived circular RNAs and their potential roles in ovarian aging

Circular RNAs (circRNAs) have recently been shown to exert effects on multiple pathological processes by acting as miRNA sponges. However, the roles of circRNAs in ovarian senescence are largely unknown. The objective of this study was to identify the circRNAs involved in ovarian aging and predict their potential biological functions. We first performed RNA-sequencing to generate ovarian circRNA expression profiles from young (n = 3) and aging (n = 3) groups. In total, 48,220 circRNAs were identified, of which 194 circRNAs were significantly up-regulated and 207 circRNAs were down-regulated during aging (fold change > 2, P < 0.05). Bioinformatics analysis demonstrated that the metabolic process, regulated secretory pathway, oxidation-reduction process, steroid hormone biosynthesis, and insulin secretion pathways, which may be associated with ovarian aging, were significantly enriched (P < 0.05). The biological characteristics of ovary-derived circRNA, such as back-splicing, RNase R resistance, stability, and alternative splicing, were further validated. Bioinformatics predicted that most of the circRNAs harboured miRNA binding sites, of which circDDX10-miR-1301-3p/miR-4660-SIRT3 axis may be involved in the regulation of ovarian function. Our study indicates that circRNAs are aberrantly expressed in the aging ovary and may play potential roles in the development of ovarian senescence.

Sirtuins and SIRT6 in Carcinogenesis and in Diet

Sirtuins are a highly conserved family of nicotinamide adenine dinucleotide (NAD)-dependent protein lysine modifying enzymes. They are key regulators for a wide variety of cellular and physiological processes such as cell proliferation, differentiation, DNA damage and stress response, genome stability, cell survival, metabolism, energy homeostasis, organ development and aging. Aging is one of the major risk factors of cancer, as many of the physiological mechanisms and pathologies associated with the aging process also contribute to tumor initiation, growth and/or metastasis. This review focuses on one the mammalian sirtuins, SIRT6, which has emerged as an important regulator of longevity and appears to have multiple biochemical functions that interfere with tumor development and may be useful in cancer prevention and for site-specific treatment. The recent evidence of the role of SIRT6 in carcinogenesis is also discussed, focusing on the potential use of SIRT6 modulators in cancer nanomedicine.

Heterosis extends the reproductive ability in aged female mice†

Heterosis is the beneficial effect of genetical heterogeneity in animals and plants. Although heterosis induces changes in the cells and individual abilities, few reports have described the effect of heterosis on the female reproductive ability during aging. In this study, we investigated the reproductive capability of genetically heterogeneous (HET) mice established by the four-way crossing of C57BL/6N, BALB/c, C3H/He, and DBA/2. We found the HET females naturally and repeatedly produced offspring, even in old age (14-18 months of age). We also found that HET females showed a significantly enlarged body and organ sizes in both youth and old age. In histological analyses, the numbers of primordial follicles, primary follicles, secondary follicles, and corpora lutea were significantly increased in the old ovaries of HET females compared with those in inbred C57BL/6 mice of the same age. In vitro fertilization experiments revealed that aged HET oocytes showed identical rates of fertilization, early development, and birth compared to those of young and old C57BL/6 oocytes. We further found the significantly increased expression of sirtuin genes concomitant with the up-regulation of R-spondin2 in old HET ovaries. These results confirm the novel phenotype, characterized by fertility extension and follicular retention due to heterosis, in old HET females. The HET female will be a valuable model for clarifying the mechanism underlying the effect of heterosis in the field of reproduction.

Effects of icariin on ovarian function in d-galactose-induced aging mice

In this study, effects of icariin (Ica) on were examined in a mouse model of d-galactose (D-gal)-induced ovarian aging. Kunming white mice were divided into three groups: aging group induced with D-gal, experiment group treated with Ica at low (50 mg/kg), middle (100 mg/kg) and high (200 mg/kg) concentrations, and control group with no treatment. Ovarian histomorphology, serum FSH, LH and E2 levels, and reproductive function were compared among the groups. Ovarian expression of Amh, Bax and Bcl-2 was examined by qPCR and western blotting. Our results showed that diameters of secondary and tertiary follicles were significantly reduced in the aging group when compared with control group (P < 0.01), and were restored to normal in Ica 100 and Ica 200 treatment groups. The diameter of atretic follicles was significantly smaller in the aging group compared with control group and Ica 200 treatment group (P < 0.05). The proportion of secondary and atretic follicles was higher in the aging group compared with control group, Ica 100 and 200 treatment groups, whereas the proportion of tertiary and mature follicles was reduced in the aging group versus control, Ica 100 and 200 groups. The aging group lacked mature follicles, whereas Ica treatment induced mature follicle development. Primary and secondary follicles exhibited similar theca cell numbers and theca interna and externa cell layers in all groups examined, whereas theca interna and externa cell layers were decreased and increased, respectively, in tertiary follicles of aging group compared with control and I 200 groups. In the aging group, FSH and LH levels were significantly higher than those in control and Ica 200 groups (P < 0.05), and the E2 level was significantly reduced compared with control (P < 0.01), Ica 200 (P < 0.01), and Ica 100 (P < 0.05) groups. Serum hormone levels were equivalent in the control, Ica 100 and Ica 200 groups. The pregnancy rate was reduced in the aging group compared with other groups. The average litter size per birth, birth litter weight, and weaning weight of litters were all significantly lower in the aging group compared with control, Ica 100 and 200 groups (P < 0.05). The ovarian expression of AMH and Bcl-2 mRNA was significantly reduced in the aging group compared with those in control and Ica-treated groups (P < 0.01). In contrast, Bax expression was significantly higher in the aging group compared with all other groups (P < 0.01), and the Bcl-2/Bax ratio was markedly reduced in aging group compared with control, Ica 100 and 200 groups (P < 0.01), and Ica 50 group (P < 0.05). Ovarian expression of AMH protein was elevated in the Ica 100 group compared with the aging, control and Ica 50 groups (P < 0.01) and Ica 200 group (P < 0.05). Ovarian Bcl-2 protein levels and the Bcl-2/Bax ratio were significantly higher in the Ica 100 group than those in the Ica 50, 200 and aging groups (P < 0.05), and were similar or reduced (P < 0.05), respectively, compared to those in control group. Ovarian Bax expression was similar in each group. These findings suggest that Ica can improve ovarian follicular development, inhibit follicular atresia, decrease FSH and LH levels and increase E2, upregulate ovarian AMH expression and increase the Bcl-2/Bax ratio in aging mice. Therefore, Ica can partially restore ovarian function of aging mice and enhance their fertility. Optimal reproductive effects were obtained with the Ica 100 group.

Serum and follicular fluid levels of sirtuin 1, sirtuin 6, and resveratrol in women undergoing in vitro fertilization: an observational, clinical study

Objective

This observational, clinical study was designed to assess the role of sirtuin 1 (SIRT1), sirtuin 6 (SIRT6), and resveratrol in in vitro fertilization (IVF).

Methods

Paired serum and follicular fluid (FF) samples were obtained from 30 consecutive patients (age: 36.43 ± 4.17 years, body mass index: 22.90 ± 2.05 kg/m², duration of infertility: 5.10 ± 2.80 years) who received IVF treatment. SIRT1, SIRT6, and resveratrol levels were measured by enzyme-linked immunosorbent assay.

Results

Ovarian hyperstimulation resulted in significantly higher serum SIRT1 levels in pregnant women (8 patients) compared with non-pregnant women (22 patients). SIRT6 levels remained unchanged after ovarian hyperstimulation, but were significantly lower in pregnant women compared with non-pregnant women before and after hyperstimulation. Both SIRTs were detected in FF, but they appeared to be independent of their serum levels. After correction for confounders, FF SIRT6 levels were positively related to mature oocytes (F = 6.609), whereas serum SIRT1 and SIRT6 levels were related to clinical pregnancy (F = 10.008, F = 5.268, respectively).

Conclusions

Our study shows that SIRT1 and SIRT6, but not resveratrol, are involved in human reproduction and they may have a role in oocyte maturation and clinical pregnancy in IVF.

Small molecule natural compound agonist of SIRT3 as a therapeutic target for the treatment of intervertebral disc degeneration

Oxidative stress-induced mitochondrial dysfunction is implicated in the pathogenesis of intervertebral disc degeneration (IVDD). Sirtuin 3 (SIRT3), a sirtuin family protein located in mitochondria, is essential for mitochondrial homeostasis; however, the role of SIRT3 in the process of IVDD has remained elusive. Here, we explored the expression of SIRT3 in IVDD in vivo and in vitro; we also explored the role of SIRT3 in senescence, apoptosis, and mitochondrial homeostasis under oxidative stress. We subsequently activated SIRT3 using honokiol to evaluate its therapeutic potential for IVDD. We assessed SIRT3 expression in degenerative nucleus pulposus (NP) tissues and oxidative stress-induced nucleus pulposus cells (NPCs). SIRT3 was knocked down by lentivirus and activated by honokiol to determine its role in oxidative stress-induced NPCs. The mechanism by which honokiol affected SIRT3 regulation was investigated in vitro, and the therapeutic potential of honokiol was assessed in vitro and in vivo. We found that the expression of SIRT3 decreased with IVDD, and SIRT3 knockdown reduced the tolerance of NPCs to oxidative stress. Honokiol (10 μM) improved the viability of NPCs under oxidative stress and promoted their properties of anti-oxidation, mitochondrial dynamics and mitophagy in a SIRT3-dependent manner. Furthermore, honokiol activated SIRT3 through the AMPK-PGC-1α signaling pathway. Moreover, honokiol treatment ameliorated IVDD in rats. Our study indicated that SIRT3 is involved in IVDD and showed the potential of the SIRT3 agonist honokiol for the treatment of IVDD.

From Implantation to Birth: Insight into Molecular Melatonin Functions

Melatonin is a lipophilic hormone synthesized and secreted mainly in the pineal gland, acting as a neuroendocrine transducer of photoperiodic information during the night. In addition to this activity, melatonin has shown an antioxidant function and a key role as regulator of physiological processes related to human reproduction. Melatonin is involved in the normal outcome of pregnancy, beginning with the oocyte quality, continuing with embryo implantation, and finishing with fetal development and parturition. Melatonin has been shown to act directly on several reproductive events, including folliculogenesis, oocyte maturation, and corpus luteum (CL) formation. The molecular mechanism of action has been investigated through several studies which provide solid evidence on the connections between maternal melatonin secretion and embryonic and fetal development. Melatonin administration, reducing oxidative stress and directly acting on its membrane receptors, melatonin thyroid hormone receptors (MT1 and MT2), displays effects on the earliest phases of pregnancy and during the whole gestational period. In addition, considering the reported positive effects on the outcomes of compromised pregnancies, melatonin supplementation should be considered as an important tool for supporting fetal development, opening new opportunities for the management of several reproductive and gestational pathologies.

Molecular and phenotypic biomarkers of aging

Individuals of the same age may not age at the same rate. Quantitative biomarkers of aging are valuable tools to measure physiological age, assess the extent of ‘healthy aging’, and potentially predict health span and life span for an individual. Given the complex nature of the aging process, the biomarkers of aging are multilayered and multifaceted. Here, we review the phenotypic and molecular biomarkers of aging. Identifying and using biomarkers of aging to improve human health, prevent age-associated diseases, and extend healthy life span are now facilitated by the fast-growing capacity of multilevel cross-sectional and longitudinal data acquisition, storage, and analysis, particularly for data related to general human populations. Combined with artificial intelligence and machine learning techniques, reliable panels of biomarkers of aging will have tremendous potential to improve human health in aging societies.

Multiple pathways of SIRT6 at the crossroads in the control of longevity, cancer, and cardiovascular diseases

Sirtuin 6 (SIRT6) is a member of the sirtuin family NAD⁺-dependent deacetylases with multiple roles in controlling organism homeostasis, lifespan, and diseases. Due to its complex and opposite functional roles, this sirtuin is considered a two-edged sword in health and disease. Indeed, SIRT6 improves longevity, similarly to the founding yeast member, silent information regulator-2 (Sir2), and modulates genome stability, telomere integrity, transcription, and DNA repair. Its deficiency is associated with chronic inflammation, diabetes, cardiac hypertrophy, obesity, liver dysfunction, muscle/adipocyte disorders, and cancer. Besides, pieces of evidence showed that SIRT6 is a promoter of specific oncogenic pathways, thus disclosing its dual role regarding cancer development. Collectively, these findings suggest that multiple mechanisms, to date not entirely known, underlie the intriguing roles of SIRT6. Here we provide an overview of the current molecular mechanisms through which SIRT6 controls cancer and heart diseases, and describe its recent implications in the atherosclerotic plaque development.

Transcriptomic features of Pecten maximus oocyte quality and maturation

The king scallop Pecten maximus is a high valuable species of great interest in Europe for both fishery and aquaculture. Notably, there has been an increased investment to produce seed for enhancement programmes of wild scallop populations. However, hatchery production is a relatively new industry and it is still underdeveloped. Major hurdles are spawning control and gamete quality. In the present study, a total of 14 scallops were sampled in the bay of Brest (Brittany, France) to compare transcriptomic profiles of mature oocytes collected by spawning induction or by stripping. To reach such a goal, a microarray analysis was performed by using a custom 8x60K oligonucleotide microarray representing 45,488 unique scallop contigs. First we identified genes that were differentially expressed depending on oocyte quality, estimated as the potential to produce D-larvae. Secondly, we investigated the transcriptional features of both stripped and spawned oocytes. Genes coding for proteins involved in cytoskeletal dynamics, serine/threonine kinases signalling pathway, mRNA processing, response to DNA damage, apoptosis and cell-cycle appeared to be of crucial importance for both oocyte maturation and developmental competence. This study allowed us to dramatically increase the knowledge about transcriptional features of oocyte quality and maturation, as well as to propose for the first time putative molecular markers to solve a major bottleneck in scallop aquaculture.

Long-term melatonin treatment delays ovarian aging

Ovarian aging is characterized by gradual declines in oocyte quantity and quality. Melatonin is considered an anti-aging agent due to its cytoprotective actions as an antioxidant. This study examined whether long-term melatonin treatment would delay ovarian aging in mice. Female ICR mice (10 weeks old) were given melatonin-containing water (100 μg/mL; melatonin) or water only until 43 weeks of age. Their oocytes were recovered from the oviduct, and in vitro fertilization was performed. The ovaries were used for a histological analysis of the number of follicles. The mRNA expression of the aging-related sirtuin genes (SIRT1, SIRT3) and the autophagy-related gene (LC3) and the telomere length of the ovarian chromosomes were analyzed. Transcriptome changes in the ovaries were also characterized using microarray. The number of ovulated oocytes decreased with age; however, it was greater in melatonin-treated mice than that from control animals. The decreased fertilization rate and blastocyst rate during aging also were higher in the melatonin-treated mice than in the controls, as were the numbers of primordial, primary, and antral follicles. The mRNA expression of SIRT1 and LC3 and telomere length were enhanced due to melatonin treatment. Seventy-eight genes that were downregulated during aging and upregulated by melatonin were identified by a microarray analysis. Forty of these 78 genes were ribosome-related genes, and a free radical scavenging network was identified. The present results indicate that melatonin delays ovarian aging by multiple mechanisms including antioxidant action, maintaining telomeres, stimulating SIRT expression and ribosome function, and by reducing autophagy.

The Role and Application of Sirtuins and mTOR Signaling in the Control of Ovarian Functions

The present short review demonstrates the involvement of sirtuins (SIRTs) in the control of ovarian functions at various regulatory levels. External and endocrine factors can affect female reproduction via SIRTs-mammalian target of rapamycin (mTOR) system, which, via hormones and growth factors, can in turn regulate basic ovarian functions (proliferation, apoptosis, secretory activity of ovarian cells, their response to upstream hormonal regulators, ovarian folliculo- and oogenesis, and fecundity). SIRTs and SIRTs-related signaling molecules and drugs regulating mTOR can be used for characterization, prediction, and regulation of ovarian functions, as well as for diagnostics and treatment of ovarian disorders.