Nucleotide variations in mitochondrial DNA and supra-physiological ROS levels in cytogenetically normal cases of premature ovarian insufficiency

Stem cell-based therapeutic potential in female ovarian aging and infertility

Premature ovarian insufficiency (POI) is defined as onset of menopause characterized by amenorrhea, hypergonadotropism, and hypoestrogenism, before the age of 40 years. The POI is increasing, which seriously affects the quality of patients' life. Due to its diversity of pathogenic factors, complex pathogenesis and limited treatment methods, the search for finding effective treatment of POI has become a hotspot. Stem cells are characterized by the ability of self-renewal and differentiation and play an important role in the regeneration of injured tissues, which is therapy is expected to be used in the treatment of POI. The aim of this review is to summarize the pathogenic mechanisms and the research progress of POI treatment with stem cells from different sources.

Mechanisms of mitochondrial dysfunction in ovarian aging and potential interventions

Mitochondria plays an essential role in regulating cellular metabolic homeostasis, proliferation/differentiation, and cell death. Mitochondrial dysfunction is implicated in many age-related pathologies. Evidence supports that the dysfunction of mitochondria and the decline of mitochondrial DNA copy number negatively affect ovarian aging. However, the mechanism of ovarian aging is still unclear. Treatment methods, including antioxidant applications, mitochondrial transplantation, emerging biomaterials, and advanced technologies, are being used to improve mitochondrial function and restore oocyte quality. This article reviews key evidence and research updates on mitochondrial damage in the pathogenesis of ovarian aging, emphasizing that mitochondrial damage may accelerate and lead to cellular senescence and ovarian aging, as well as exploring potential methods for using mitochondrial mechanisms to slow down aging and improve oocyte quality.

New insights on mitochondrial heteroplasmy observed in ovarian diseases

BACKGROUND

The reportedly high mutation rate of mitochondrial DNA (mtDNA) may be attributed to the absence of histone protection and complete repair mechanisms. Mitochondrial heteroplasmy refers to the coexistence of wild-type and mutant mtDNA. Most healthy individuals carry a low point mutation load (<1 %) in their mtDNA, typically without any discernible phenotypic effects. However, as it exceeds a certain threshold, it may cause the onset of various diseases. Since the ovary is a highly energy-intensive organ, it relies heavily on mitochondrial function. Mitochondrial heteroplasmy can potentially contribute to a variety of significant ovarian disorders.

AIM OF REVIEW

In this review, we have elucidated the close relationship between mtDNA heteroplasmy and ovarian diseases, and summarized novel avenues and strategies for the potential treatment of these ovarian diseases.

KEY SCIENTIFIC CONCEPTS OF REVIEW

Mitochondrial heteroplasmy can potentially contribute to a variety of significant ovarian disorders, including polycystic ovary syndrome, premature ovarian insufficiency, and endometriosis. Current strategies related to mitochondrial heteroplasmy are untargeted and have low bioavailability. Nanoparticle delivery systems loaded with mitochondrial modulators, mitochondrial replacement/transplantation therapy, and mitochondria-targeted gene editing therapy may offer promising paths towards potentially more effective treatments for these diseases, despite ongoing challenges.

β-Nicotinamide Mononucleotide Alleviates Hydrogen Peroxide-Induced Cell Cycle Arrest and Death in Ovarian Granulosa Cells

Maintaining normal functions of ovarian granulosa cells (GCs) is essential for oocyte development and maturation. The dysfunction of GCs impairs nutrition supply and estrogen secretion by follicles, thus negatively affecting the breeding capacity of farm animals. Impaired GCs is generally associated with declines in Nicotinamide adenine dinucleotide (NAD+) levels, which triggers un-controlled oxidative stress, and the oxidative stress, thus, attack the subcellular structures and cause cell damage. β-nicotinamide mononucleotide (NMN), a NAD+ precursor, has demonstrated well-known antioxidant properties in several studies. In this study, using two types of ovarian GCs (mouse GCs (mGCs) and human granulosa cell line (KGN)) as cell models, we aimed to investigate the potential effects of NMN on gene expression patterns and antioxidant capacity of both mGCs and KGN that were exposed to hydrogen peroxide (H2O2). As shown in results of the study, mGCs that were exposed to H2O2 significantly altered the gene expression patterns, with 428 differentially expressed genes (DEGs) when compared with those of the control group. Furthermore, adding NMN to H2O2-cultured mGCs displayed 621 DEGs. The functional enrichment analysis revealed that DEGs were mainly enriched in key pathways like cell cycle, senescence, and cell death. Using RT-qPCR, CCK8, and β-galactosidase staining, we found that H2O2 exposure on mGCs obviously reduced cell activity/mRNA expressions of antioxidant genes, inhibited cell proliferation, and induced cellular senescence. Notably, NMN supplementation partially prevented these H2O2-induced abnormalities. Moreover, these similar beneficial effects of NMN on antioxidant capacity were confirmed in the KGN cell models that were exposed to H2O2. Taken together, the present results demonstrate that NMN supplementation protects against H2O2-induced impairments in gene expression pattern, cell cycle arrest, and cell death in ovarian GCs through boosting NAD+ levels and provide potential strategies to ameliorate uncontrolled oxidative stress in ovarian GCs.

Biological therapies for premature ovarian insufficiency: what is the evidence?

Premature Ovarian Insufficiency (POI) is a multi-factorial disorder that affects women of reproductive age. The condition is characterized by the loss of ovarian function before the age of 40 years and several factors have been identified to be implicated in its pathogenesis. Remarkably though, at least 50% of women have remaining follicles in their ovaries after the development of ovarian insufficiency. Population data show that approximately up to 3.7% of women worldwide suffer from POI and subsequent infertility. Currently, the treatment of POI-related infertility involves oocyte donation. However, many women with POI desire to conceive with their own ova. Therefore, experimental biological therapies, such as Platelet-Rich Plasma (PRP), Exosomes (exos) therapy, In vitro Activation (IVA), Stem Cell therapy, MicroRNAs and Mitochondrial Targeting Therapies are experimental treatment strategies that focus on activating oogenesis and folliculogenesis, by upregulating natural biochemical pathways (neo-folliculogenesis) and improving ovarian microenvironment. This mini-review aims at identifying the main advantages of these approaches and exploring whether they can underpin existing assisted reproductive technologies.

The Role of Lifestyle and Dietary Factors in the Development of Premature Ovarian Insufficiency

Premature ovarian insufficiency (POI) is a condition that arises from dysfunction or early depletion of the ovarian follicle pool accompanied by an earlier-than-normal loss of fertility in young women. Oxidative stress has been suggested as an important factor in the decline of fertility in women and POI. In this review, we discuss the mechanisms of oxidative stress implicated in ovarian ageing and dysfunction in relation to POI, in particular mitochondrial dysfunction, apoptosis and inflammation. Genetic defects, autoimmunity and chemotherapy, are some of the reviewed hallmarks of POI that can lead to increased oxidative stress. Additionally, we highlight lifestyle factors, including diet, low energy availability and BMI, that can increase the risk of POI. The final section of this review discusses dietary factors associated with POI, including consumption of oily fish, mitochondria nutrient therapy, melatonin, dairy and vitamins that can be targeted as potential interventions, especially for at-risk women and in combination with personalised nutrition. Understanding the impact of lifestyle and its implications for POI and oxidative stress holds great promise in reducing the burden of this condition.

Deficiency of the mitochondrial ribosomal subunit, MRPL50, causes autosomal recessive syndromic premature ovarian insufficiency

Premature ovarian insufficiency (POI) is a common cause of infertility in women, characterised by amenorrhea and elevated FSH under the age of 40 years. In some cases, POI is syndromic in association with other features such as sensorineural hearing loss in Perrault syndrome. POI is a heterogeneous disease with over 80 causative genes known so far; however, these explain only a minority of cases. Using whole-exome sequencing (WES), we identified a MRPL50 homozygous missense variant (c.335T > A; p.Val112Asp) shared by twin sisters presenting with POI, bilateral high-frequency sensorineural hearing loss, kidney and heart dysfunction. MRPL50 encodes a component of the large subunit of the mitochondrial ribosome. Using quantitative proteomics and western blot analysis on patient fibroblasts, we demonstrated a loss of MRPL50 protein and an associated destabilisation of the large subunit of the mitochondrial ribosome whilst the small subunit was preserved. The mitochondrial ribosome is responsible for the translation of subunits of the mitochondrial oxidative phosphorylation machinery, and we found patient fibroblasts have a mild but significant decrease in the abundance of mitochondrial complex I. These data support a biochemical phenotype associated with MRPL50 variants. We validated the association of MRPL50 with the clinical phenotype by knockdown/knockout of mRpL50 in Drosophila, which resulted abnormal ovarian development. In conclusion, we have shown that a MRPL50 missense variant destabilises the mitochondrial ribosome, leading to oxidative phosphorylation deficiency and syndromic POI, highlighting the importance of mitochondrial support in ovarian development and function.

Stem Cell-Based Therapeutic Strategies for Premature Ovarian Insufficiency and Infertility: A Focus on Aging

Reproductive aging is on the rise globally and inseparable from the entire aging process. An extreme form of reproductive aging is premature ovarian insufficiency (POI), which to date has mostly been of idiopathic etiology, thus hampering further clinical applications and associated with enormous socioeconomic and personal costs. In the field of reproduction, the important functional role of inflammation-induced ovarian deterioration and therapeutic strategies to prevent ovarian aging and increase its function are current research hotspots. This review discusses the general pathophysiology and relative causes of POI and comprehensively describes the association between the aging features of POI and infertility. Next, various preclinical studies of stem cell therapies with potential for POI treatment and their molecular mechanisms are described, with particular emphasis on the use of human induced pluripotent stem cell (hiPSC) technology in the current scenario. Finally, the progress made in the development of hiPSC technology as a POI research tool for engineering more mature and functional organoids suitable as an alternative therapy to restore infertility provides new insights into therapeutic vulnerability, and perspectives on this exciting research on stem cells and the derived exosomes towards more effective POI diagnosis and treatment are also discussed.

The Molecular Quality and Mitochondrial Activity of Porcine Cumulus-Oocyte Complexes Are Affected by Their Exposure to Three Endocrine-Active Compounds under 3D In Vitro Maturation Conditions

Thus far, the potential short- and long-term detrimental effects of a variety of environmental chemicals designated as endocrine-active compounds (EACs) have been found to interfere with histo- and anatomo-physiological functions of the reproductive system in humans and wildlife species. For those reasons, this study sought to examine whether selected EACs, which encompass the fungicide vinclozolin (Vnz), the androgenic anabolic steroid nandrolone (Ndn) and the immunosuppressant cyclosporin A (CsA), affect the developmental competence and molecular quality (MQ) of porcine cumulus–oocyte complexes (COCs) subjected to in vitro maturation (IVM) under 3D culture conditions. The COCs underwent 3D-IVM in the presence of Vnz, Ndn or CsA for 48 h. To explore whether the selected EACs induce internucleosomal DNA fragmentation in cumulus cells (CCs), TUNEL-assisted detection of late apoptotic cells was performed. Additionally, for the detailed evaluation of pro- and antiapoptotic pathways in COCs, apoptosis proteome profiler arrays were used. To determine changes in intracellular metabolism in COCs, comprehensive assessments of mitochondrial ultrastructure and activity were carried out. Moreover, the relative abundances (RAs) of mRNAs transcribed from genes that are involved in scavenging reactive oxygen species (ROS), such as SIRT3 and FOXO3, and intramitochondrial bioenergetic balance, such as ATP synthase subunit (ATP5A1), were ascertained. Finally, to investigate the extent of progression of oocyte maturation, the intraooplasmic levels of cAMP and the RAs of mRNA transcripts encoding regulatory and biocatalytic subunits of a heterodimeric meiosis-promoting factor, termed cyclin B1 (CCNB1) and cyclin-dependent kinase 1 (CDC2), were also estimated. The obtained results provide, for the first time, strong evidence that both Vnz and Ndn decrease the developmental competence of oocytes and stimulate apoptosis processes in CCs. The present study is also the first to highlight that Vnz accelerates the maturation process in immature oocytes due to both increased ROS production and the augmented RA of the CCNB1 gene. Furthermore, Vnz was proven to trigger proapoptotic events in CCs by prompting the activity of the FOXO3 transcription factor, which regulates the mitochondrial apoptosis pathway. In turn, Ndn was shown to inhibit oocyte maturation by inducing molecular events that ultimately lead to an increase in the intraooplasmic cAMP concentration. However, due to the simultaneous enhancement of the expression of TNF-β and HSP27 proteins in CCs, Ndn might be responsible for the onset of their neoplastic transformation. Finally, our current investigation is the first to clearly demonstrate that although CsA did not interfere with the nuclear and cytoplasmic maturation of oocytes, by inducing mitophagy in CCs, it disrupted oocyte metabolism, consequently attenuating the parameters related to the MQ of COCs. Summing up, Vnz, Ndn and CsA reduced not only the processes of growth and IVM but also the MQ of porcine COCs, which might make them unsuitable for assisted reproductive technologies (ARTs) such as in vitro fertilization by either gamete co-incubation or intracytoplasmic sperm injection (ICSI) and cloning by somatic cell nuclear transfer (SCNT).

Therapeutic options for premature ovarian insufficiency: an updated review

Primary ovarian insufficiency (POI) is a rare gynecological condition. This disease causes menstrual disturbances, infertility, and various health problems. Historically, hormone replacement therapy is the first-line treatment for this disorder. Women diagnosed with POI are left with limited therapeutic options. In order to remedy this situation, a new generation of therapeutic approaches, such as in vitro activation, mitochondrial activation technique, stem cell and exosomes therapy, biomaterials strategies, and platelet-rich plasma intra-ovarian infusion, is being developed. However, these emerging therapies are yet in the experimental stage and require precise design components to accelerate their conversion into clinical treatments. Thus, each medical practitioner bears responsibility for selecting suitable therapies for individual patients. In this article, we provide a timely analysis of the therapeutic strategies that are available for POI patients and discuss the prospects of POI therapy.

A case-control study of thallium exposure with the risk of premature ovarian insufficiency in women

Thallium exposure has been associated with female reproductive health, but little is known about its potential association with premature ovarian insufficiency (POI). In this study, a total of 169 patients with POI and 209 healthy women were recruited from Zhejiang province, China. Urinary thallium concentrations were significantly positively associated with the risk of POI [adjusted odds ratio (OR) = 1.63, 95% CI: 1.25-2.13, p < 0.001], geometric mean values of which were significantly higher in POI cases (0.213 μg/L, 0.302 μg/g for creatinine adjustment) than those of controls (0.153 μg/L, 0.233 μg/g for creatinine adjustment). Furthermore, the serum levels of follicle-stimulating hormone and luteinizing hormone were positively associated with urinary thallium concentrations, whereas anti-Mullerian hormone and estradiol were negatively correlated with thallium. To the best of our knowledge, this is the first study to provide evidence that thallium exposure at currently environmental levels is the potential risk factor for POI in women.

Long non-coding RNA lnc-CCNL1-3:1 promotes granulosa cell apoptosis and suppresses glucose uptake in women with polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is a common endocrine and metabolic disease in premenopausal women. Long non-coding RNAs (lncRNAs) constitute important factors in numerous biological processes. However, their roles in PCOS pathogenesis require further clarification. Our study aims to elucidate the roles of lncRNA lnc-CCNL1-3:1 (CCNL) in PCOS. CCNL expression in human luteinized granulosa cells (hLGCs) derived from women with and without PCOS was detected. The full length of CCNL was obtained by 5' and 3' rapid amplification of cDNA ends. CCNL roles in granulosa cell apoptosis, mitochondrial function, and glucose uptake were evaluated. The binding relationship between CCNL and forkhead box O1 (FOXO1) was determined by RPISeq, RNA immunoprecipitation, subcellular fractionation, and immunofluorescence. In KGN cells and hLGCs, CCNL overexpression upregulated FOXO1 expression, promoted cell apoptosis, reduced glucose transport capability, and impaired mitochondrial function, and these effects were partially abolished by silencing FOXO1. The interaction of CCNL with FOXO1 might prevents FOXO1 exclusion from the nucleus and subsequent degradation in the cytosol. We determined that CCNL serve as a facilitator in the processes of PCOS. CCNL might participate in PCOS pathologies such as follicular atresia and insulin resistance.

Autophagy Contributes to Oxidative Stress-Induced Apoptosis in Porcine Granulosa Cells

Oxidative stress-induced granulosa cell (GC) death is a major cause of follicular atresia. As the major types of programmed cell death, autophagy and apoptosis have been observed in response to H₂O₂-mediated oxidative stress and have been demonstrated to be responsible for porcine GC death. To date, however, the cellular reactions linking autophagy to the apoptosis of porcine GC under oxidative stress are still poorly understood. Porcine GC were treated with H₂O₂, and autophagic flux was examined by western blotting. Cell viability and cell death assays were performed after cotreatment of porcine GC with autophagy activator (rapamycin) or inhibitor (3-methyladenine, 3-MA) together with H₂O₂. We revealed that short exposure (1-3 h) of porcine GC to H₂O₂ dramatically increased autophagic flux (1.8- to 2.5-fold over that in the control), whereas 6-12 h prolonged treatment decreased autophagy but elevated the caspase-3 activity and GC apoptotic rate. Furthermore, we showed that pretreatment with rapamycin exacerbated H₂O₂-mediated cytotoxicity and caspase-3 activation but that 3-MA or siRNAs specific for Beclin 1 and Atg7 genes ameliorated H₂O₂-mediated GC apoptosis. Together, our results indicate that autophagy plays a pivotal role in H₂O₂-mediated porcine GC apoptosis. Importantly, we show that the early induction of autophagic flux contributes to oxidative stress-induced apoptosis in porcine GC. The results also suggest that regulating the autophagy response in porcine GC under oxidative stress might be a new strategy for abnormal follicular atresia.

MicroRNA-181a promotes follicular granulosa cell apoptosis via sphingosine-1-phosphate receptor 1 expression downregulation†

Oxidative stress induces granulosa cell (GC) apoptosis and subsequent follicular atresia. Since our previous studies indicate that microRNA-181a (miR-181a) expression is increased in GCs undergoing apoptosis, the present study was designed to define the relationship between exposure to oxidative stressors in GCs and changes in miR-181a expression and function. To achieve this, we employed an H2O2-induced in vitro model and a 3-nitropropionic acid-induced in vivo model of ovarian oxidative stress. We demonstrated that in vitro miR-181a overexpression promoted GC apoptosis in a dose-dependent manner; sphingosine-1-phosphate (S1P) significantly reversed both H2O2-induced and miR-181a-induced apoptosis in GCs. Moreover, we identified sphingosine-1-phosphate receptor 1 (S1PR1), a critical receptor of S1P, as a novel target of miR-181a in GCs. MicroRNA-181a induced GC apoptosis by repressing S1PR1 expression in vitro. Importantly, increased miR-181a expression and decreased S1PR1 expression were detected in the in vivo ovarian oxidative stress model by Western blot analysis and immunohistochemistry. Furthermore, we found similar expression patterns of miR-181a and S1PR1 in GCs from patients with premature ovarian insufficiency. In conclusion, our results suggest that miR-181a directly suppresses expression of S1PR1, which has critical roles in mediating oxidative stress-induced GC apoptosis both in vitro and in vivo.

The role of oxidative stress on subclinical atherosclerosis in premature ovarian insufficiency and relationship with carotid intima-media thickness

Objective: We aimed to investigate the relationship between oxidative stress (OS) and subclinical atherosclerosis in patients with premature ovarian insufficiency (POI), by analyzing the dynamic thiol/disulfide homeostasis (TDH) parameters as an OS marker and carotid intima-media thickness (CIMT).Materials and methods: A total of 69 women, 34 with POI and 35 healthy controls were included in this prospective cross-sectional study. TDH parameters (plasma native thiol, total thiol, disulfide, disulfide/native thiol, native thiol/total thiol, and disulfide/total thiol ratios) and CIMT were measured and compared between the two groups.Results: In primary ovarian insufficiency group, native thiol (p=.009) and total thiol (p=.010) levels were significantly decreased, and CIMT values were significantly increased (p= <.001). CIMT values were negatively correlated with native thiol (r=-0.553, p=.001) and total thiol levels (r=-0.565, p=.001); and positively correlated with age (r = 0.457, p=.007), BMI (r = 0.408, p=.017), and total cholesterol (r = 0.605, p<.001) in POI group.Conclusions: Decreased native thiol and total thiol levels demonstrate the defective anti-oxidant mechanism in POI. Negative correlation between native thiol, total thiol levels, and CIMT means the presence of abnormal anti-oxidant mechanisms may play a role in the development of subclinical atherosclerosis in patients with POI. This is a novel report on the mechanism of subclinical atherosclerosis in women with POI, which needs to be supported with further studies evaluating the pathophysiology of OS.

A case-control study of arsenic exposure with the risk of primary ovarian insufficiency in women

Arsenic, a well-known toxic metalloid, is ubiquitously existed in environment. Arsenic exposure has been associated with female reproductive health. However, a potential association between arsenic exposure and primary ovarian insufficiency (POI) in women has not been recognized yet. In this case-control study, a total of 169 POI cases and 209 healthy controls were recruited to determine urinary concentrations of arsenic and serum levels of reproductive hormones (follicle-stimulating hormone (FSH), luteinizing hormone (LH), anti-Mullerian hormone (AMH) and estradiol). The median concentration of urinary arsenic in cases (21.5 μg/L, 28.0 μg/g for creatinine adjustment) was significantly higher than that of controls (13.8 μg/L, 19.3 μg/g for creatinine adjustment). Urinary arsenic concentrations were significantly positively associated with the risk of POI (adjusted odds ratio (OR) = 2.66, 95% CI: 1.43-4.95 for the highest vs lowest tertile of arsenic, p = 0.002; p for trend = 0.004). We also assessed the associations between arsenic exposure and reproductive hormones that are important for ovarian functions. FSH and LH levels were positively associated with urinary arsenic, whereas AMH and estradiol levels were negatively correlated with this element. This study provided evidence that arsenic exposure could be the potential risk factor for POI in women.

Exosomal miRNA-17-5p derived from human umbilical cord mesenchymal stem cells improves ovarian function in premature ovarian insufficiency by regulating SIRT7

Premature ovarian insufficiency (POI) is clinically irreversible in women aged over 40 years. Although numerous studies have demonstrated satisfactory outcomes of mesenchymal stem cell therapy, the underlying therapeutic mechanism remains unclear. Exosomes were collected from the culture medium of human umbilical cord mesenchymal stem cells (hUMSCs) and assessed by electron microscopy and Western blot (WB) analysis. Then, exosomes were added to the culture medium of cyclophosphamide (CTX)-damaged human granulosa cells (hGCs), and the mixture was injected into the ovaries of CTX-induced POI model mice before detection of antiapoptotic and apoptotic gene expression. Next, the microRNA expression profiles of hUMSC-derived exosomes (hUMSC-Exos) were detected by small RNA sequencing. The ameliorative effect of exosomal microRNA-17-5P (miR-17-5P) was demonstrated by miR-17-5P knockdown before assessment of ovarian phenotype and function, reactive oxygen species (ROS) levels and SIRT7 expression. Finally, SIRT7 was inhibited or overexpressed by RNA interference or retrovirus transduction, and the protein expression of PARP1, γH2AX, and XRCC6 was analyzed. The ameliorative effect of hUMSC-Exos on POI was validated. Our results illustrated that hUMSC-Exos restored ovarian phenotype and function in a POI mouse model, promoted proliferation of CTX-damaged hGCs and ovarian cells, and alleviated ROS accumulation by delivering exosomal miR-17-5P and inhibiting SIRT7 expression. Moreover, our findings elucidated that miR-17-5P repressed PARP1, γH2AX, and XRCC6 by inhibiting SIRT7. Our findings suggest a critical role for exosomal miR-17-5P and its downstream target mRNA SIRT7 in hUMSC transplantation therapy. This study indicates the promise of exosome-based therapy for POI treatment.

Grape Seed Procyanidin B2 Protects Porcine Ovarian Granulosa Cells against Oxidative Stress-Induced Apoptosis by Upregulating let-7a Expression

Oxidative stress is a causal factor and key promoter of all kinds of reproductive disorders related to granulosa cell (GC) apoptosis that acts by dysregulating the expression of related genes. Various studies have suggested that grape seed procyanidin B2 (GSPB2) may protect GCs from oxidative injury, though the underlying mechanisms are not fully understood. Therefore, whether the beneficial effects of GSPB2 are associated with microRNAs, which have been suggested to play a critical role in GC apoptosis by regulating the expression of protein-coding genes, was investigated in this study. The results showed that GSPB2 treatment protected GCs from a H₂O₂-induced apoptosis, as detected by an MTT assay and TUNEL staining, and increased let-7a expression in GCs. Furthermore, let-7a overexpression markedly increased cell viability and inhibited H₂O₂-induced GC apoptosis. Furthermore, the overexpression of let-7a reduced the upregulation of Fas expression in H₂O₂-treated GCs at the mRNA and protein levels. Dual-luciferase reporter assay results indicated that let-7a directly targets the Fas 3′-UTR. Furthermore, the overexpression of let-7a enhanced the protective effects of GSPB2 against GC apoptosis induced by H₂O₂. These results indicate that GSPB2 inhibits H₂O₂-induced apoptosis of GCs, possibly through the upregulation of let-7a.

Mitochondrial Dysfunction in Primary Ovarian Insufficiency

Primary ovarian insufficiency (POI) is defined by the loss or dysfunction of ovarian follicles associated with amenorrhea before the age of 40. Symptoms include hot flashes, sleep disturbances, and depression, as well as reduced fertility and increased long-term risk of cardiovascular disease. POI occurs in ∼1% to 2% of women, although the etiology of most cases remains unexplained. Approximately 10% to 20% of POI cases are due to mutations in a single gene or a chromosomal abnormality, which has provided considerable molecular insight into the biological underpinnings of POI. Many of the genes for which mutations have been associated with POI, either isolated or syndromic cases, function within mitochondria, including MRPS22, POLG, TWNK, LARS2, HARS2, AARS2, CLPP, and LRPPRC. Collectively, these genes play roles in mitochondrial DNA replication, gene expression, and protein synthesis and degradation. Although mutations in these genes clearly implicate mitochondrial dysfunction in rare cases of POI, data are scant as to whether these genes in particular, and mitochondrial dysfunction in general, contribute to most POI cases that lack a known etiology. Further studies are needed to better elucidate the contribution of mitochondria to POI and determine whether there is a common molecular defect in mitochondrial function that distinguishes mitochondria-related genes that when mutated cause POI vs those that do not. Nonetheless, the clear implication of mitochondrial dysfunction in POI suggests that manipulation of mitochondrial function represents an important therapeutic target for the treatment or prevention of POI.

Premature ovarian insufficiency may be associated with the mutations in mitochondrial tRNA genes

Premature ovarian insufficiency (POI) is a common endocrine disorder featured by the triad constituting of amenorrhea for at least four months, to date, the molecular pathogenesis of POI is largely undetermined. Despite several investigations have reported an increase in reactive oxygen species (ROS) content in idiopathic POI, the role of mitochondrial DNA (mtDNA) mutations/variants in the progression of POI has not been widely investigated. The current study aimed to explore the association between mt-tRNA mutations/variants and POI; we first used the PCR-Sanger sequencing to detect the mutations/variants in mt-tRNA genes from 50 POI patients and 30 healthy subjects. In addition, we evaluated the mitochondrial functions by using trans-mitochondrial cybrid cells containing these potential pathogenic mt-tRNA mutations. Consequently, five mutations: tRNA^Leu(UUR) C3303T, tRNA^Met A4435G, tRNA^Gln T4363C, tRNA^Cys G5821A and tRNA^Thr A15951G were identified. Notably, these mutations occurred at the extremely conserved nucleotides of the corresponding mt-tRNAs and may result the failure in mt-tRNA metabolism and subsequently lead to the impairment in mitochondrial protein synthesis. Furthermore, biochemical and molecular analyses of the cybrid cells containing these mutations showed a significantly lower level of ATP production when compared with the controls, whereas the ROS levels were much higher in POI patients carrying these mt-tRNA mutations, strongly indicated that these mt-tRNA mutations may cause the mitochondrial dysfunction, and play active roles in the progression and pathogensis of POI. Together, this study shaded additional light on the molecular mechanism of POI that was manifestated by mt-tRNA mutations.

MicroRNA-145 protects follicular granulosa cells against oxidative stress-induced apoptosis by targeting Krüppel-like factor 4

Oxidative stress-induced follicular granulosa cell (GC) apoptosis plays an essential role in abnormal follicular atresia, which may trigger ovarian dysfunction. To investigate the role of microRNA (miR)-145 in the regulation of GC apoptosis and modulation of the apoptotic pathway in the setting of oxidative stress, we employed an H2O2-induced in vitro model and a 3-nitropropionic acid (NP)-induced in vivo model of ovarian oxidative stress. We demonstrated in vitro that miR-145 expression was significantly down-regulated in KGN cells and mouse granulosa cells (mGCs) treated with H2O2, whereas miR-145 over-expression attenuated H2O2-induced apoptosis in GCs. Moreover, miR-145 protected GCs against H2O2-induced apoptosis by targeting KLF4, which promoted H2O2-induced GC apoptosis via the BAX/BCL-2 pathway. Importantly, decreased miR-145 expression in the in vivo ovarian oxidative stress model promoted apoptosis by up-regulating KLF4 expression, whereas GC-specific miR-145 over-expression attenuated apoptosis by targeting KLF4. In conclusion, miR-145 protects GCs against oxidative stress-induced apoptosis by targeting KLF4.

Cigarette smoke is associated with altered expression of antioxidant enzymes in granulosa cells from women undergoing in vitro fertilization

This study was undertaken to evaluate whether cigarette smoke is associated with changes in the expression of antioxidant enzymes in granulosa cells of women undergoing IVF treatments. For this aim, the expression of three antioxidant enzymes (SOD1, SOD2 and catalase) in non-smokers (n = 20) and smokers (n = 20) was analyzed. There was a statistically significant overexpression of SOD2 and catalase mRNA levels in smokers in comparison with non-smokers. Cigarette smoking was associated with a lower fertilization rate, implantation rate and pregnancy rate in comparison with non-smokers. There was no effect on retrieved oocytes number, metaphase II oocytes number, quality of embryos transferred and live birth rate. These findings suggest that cigarette smoke initiates oxidative stress in granulosa cells.

Role of inflammation and oxidative stress in the etiology of primary ovarian insufficiency

Objective:

The aim of this study was to elucidate the etiology and treatment of primary ovarian insufficiency, which is of unknown cause in 95% of the cases.

Materials and Methods:

Thirty patients aged 18-40 years who presented to Dicle University Faculty of Medicine Clinic of Obstetrics and Gynecology between June 2012 and January 2014 and were diagnosed as having primary ovarian insufficiency based on their clinical and endocrinologic data, and 30 healthy controls were included in this study.

Results:

No significant differences were found between patients with primary ovarian insufficiency and control subjects in demographic data and lipid profile levels, thyroid- stimulating hormone, prolactin, and glucose. However, the neutrophil to lymphocyte ratio and levels of follicle-stimulating hormone, luteinizing hormone, total antioxidant status, total oxidant status, and oxidative stress index were significantly higher in patients with primary ovarian insufficiency than in control subjects. In the correlation analysis, follicle-stimulating hormone exhibited a positive correlation with total oxidant status, oxidative stress index, and the neutrophil to lymphocyte ratio (r=0.573** p<0.001, r=0.584** p<0.001, r=0.541 p<0.001, respectively) and correlated negatively with total antioxidant status (r=-0.437** p<0.001).

Conclusion:

The neutrophil to lymphocyte ratio, total oxidant status, and oxidative stress index levels are elevated in primary ovarian insufficiency. Therefore, anti-oxidative and anti-inflammatory treatment might be administered to patients in the early stage of primary ovarian insufficiency. However, larger studies are needed to clarify whether these elevated levels are a cause or a consequence of primary ovarian insufficiency.

Chromosomal abnormalities & oxidative stress in women with premature ovarian failure (POF)

Background & objectives:

Premature ovarian failure (POF) is defined as the cessation of ovarian function under the age of 40 yr and is characterized by amenorrhoea, hypoestrogenism and elevated serum gonadotrophin levels. The cause of POF remains undetermined in majority of the cases. This study was aimed to investigate the type and frequency of cytogenetic abnormalities in patients with idiopathic POF and also to study the role of oxidative stress in such cases.

Methods:

Seventy five women with idiopathic POF were included in this study. Chromosome analysis was done in peripheral blood lymphocytes by conventional GTG banding to identify numerical or structural abnormalities. Cytogenetically normal cases were investigated for reactive oxygen species (ROS) levels in their blood by luminol-chemiluminescence assay.

Results:

Eighteen chromosomal anomalies were identified in POF patients (24%). Majority of the cases were found to have X-chromosome abnormalities (28%). Overall median ROS range was found to be significantly higher (P<0.01) in POF patients [50480 (120,132966) RLU/min] compared to controls [340 (120,5094) RLU/min]. Among these, 50 per cent of the POF patients had higher ROS levels, 20 per cent had medium elevation and 30 per cent were found to have normal values comparable to controls.

Interpretation & conclusions:

X-chromosome anomalies were found to be the major contributor of POF. Oxidative stress may be the underlying aetiology in idiopathic premature ovarian failure. Thus the results of this study highlight the role of cytogenetic abnormalities and supraphysiological levels of ROS in causation of idiopathic POF. But the role of oxidative stress needs to be confirmed by other studies on patients from different geographical areas and from different ethnicities.

Involvement of the up-regulated FoxO1 expression in follicular granulosa cell apoptosis induced by oxidative stress

Follicular atresia is common in female mammalian ovaries, where most follicles undergo degeneration at any stage of growth and development. Oxidative stress gives rise to triggering granulosa cell apoptosis, which has been suggested as a major cause of follicular atresia. However, the underlying mechanism by which the oxidative stress induces follicular atresia remains unclear. FoxO transcription factors are known as critical mediators in the regulation of oxidative stress and apoptosis. In this study, the involvement of FoxO1 in oxidative stress-induced apoptosis of mouse follicular granulosa cells (MGCs) was investigated in vivo and in vitro. It was observed that increased apoptotic signals correlated with elevated expression of FoxO1 in MGCs when mice were treated with the oxidant. Correspondingly, the expressions of FoxO1 target genes, such as proapoptotic genes and antioxidative genes, were also up-regulated. In primary cultured MGCs, treatment with H(2)O(2) led to FoxO1 nuclear translocation. Further studies with overexpression and knockdown of FoxO1 demonstrated the critical role of FoxO1 in the induction of MGC apoptosis by oxidative stress. Finally, inactivation of FoxO1 by insulin treatment confirmed that FoxO1 induced by oxidative stress played a pivotal role in up-regulating the expression of downstream apoptosis-related genes in MGCs. Our results suggest that up-regulation of FoxO1 by oxidative stress leads to apoptosis of granulosa cells, which eventually results in follicular atresia in mice.