Androgens Increase Accumulation of Advanced Glycation End Products in Granulosa Cells by Activating ER Stress in PCOS

Role of advanced glycation end-products in age-associated kidney dysfunction in naturally aging mice

AIMS

Advanced glycation end-products (AGEs) are implicated in the age-related decline of renal function, exacerbated by conditions, such as hyperglycemia and oxidative stress. The accumulation of AGEs in the kidneys contributes to the progressive decline in renal function observed with aging. However, the precise role and mechanisms of AGEs in the age-related decline of renal function remain unclear. In this study, we investigated the impact and potential mechanisms of AGEs on aging kidneys in naturally aging mice.

MATERIALS AND METHODS

Male C57BL/6 mice were divided into three groups: 6-, 57-, and 107-week-old. First, the 6- and 107-week-old mice were euthanized. The remaining mice were divided into young (6 weeks) and old (57 weeks) groups. The 57-week-old mice were orally administered aminoguanidine (100 mg/kg/day), an AGEs inhibitor, or vehicle for 13 weeks, resulting in a final age of 70 weeks. The serum and kidney tissues were collected for biochemical measurement, histological examination, immunohistochemistry staining, and immunoblotting analysis.

KEY FINDINGS

Our findings revealed a notable accumulation of AGEs in both serum and kidney tissue specimens and renal dysfunction in naturally aging mice. Aminoguanidine not only reversed AGEs accumulation but also ameliorated renal dysfunction. Additionally, aminoguanidine attenuated the upregulation of fibrosis markers (phosphorylated p38/α-SMA and C/EBP homologous protein, CHOP), senescence markers (p53 and p21), and oxidative stress marker (4-HNE) in the aging kidneys.

SIGNIFICANCE

These findings underscore the critical role of AGEs in age-related renal dysfunction and highlight the therapeutic potential of aminoguanidine in mitigating fibrosis and senescence, offering prospective avenues for combating age-associated renal ailments.

Endoplasmic Reticulum Stress in Myometrial Smooth Muscle Cells and Spontaneous Contraction Changes in the Uterus of Dehydroepiandrosterone-induced Polycystic Ovary Syndrome Rats

Myometrial changes in polycystic ovary syndrome (PCOS) are poorly investigated. Thus, we aimed to investigate endoplasmic reticulum (ER) stress in myometrial smooth muscle cells and changes in spontaneous uterine contraction in PCOS. Twenty-one female Sprague-Dawley rats (21 days old) were divided into control (n = 7), vehicle (n = 7) and PCOS (n = 7) groups. While the control group was not injected subcutaneously, the vehicle group was injected subcutaneously with sesame oil (0.2 ml/day) for 20 consecutive days. The PCOS group was injected subcutaneously with dehydroepiandrosterone (6 mg/100 g/day dissolved in 0.2 ml sesame oil) for 20 consecutive days. Blood samples were collected for the measurement of follicle stimulating-hormone (FSH), luteinizing hormone (LH), testosterone (T), estradiol (E2) and glucose-regulated protein 78 (GRP78). The mRNA expression of GRP78 in the uterine tissue samples was analysed by quantitative real-time polymerase chain reaction. GRP78 protein expression was assessed by immunohistochemistry. Myometrial smooth muscle cells were examined by transmission electron microscopy. Uterine contractions were evaluated with isolated organ bath experiments. In the PCOS group, T and LH levels increased significantly, although FSH and E2 levels decreased, but this decrease was not statistically significant. Additionally, GRP78 levels increased significantly in the PCOS group. In the PCOS group, the mRNA level, immunostaining intensity of GRP78, and ER damage grade increased, but the uterine tissue calcium levels, and the frequency and amplitude of spontaneous uterine contractions decreased. The results indicated that increased ER stress in myometrial smooth muscle cells may play a causative role in the decreased spontaneous uterine contractions in PCOS.

Alpha-Lipoic Acid Ameliorates Impaired Steroidogenesis in Human Granulosa Cells Induced by Advanced Glycation End-Products

Background

Ovarian granulosa cells (GCs) are essential for follicular development. Ovarian advanced glycation end-products (AGEs) accumulation is related to GCs dysfunction. Alpha-lipoic acid (ALA) illustrates therapeutic capabilities for infertility-related disorders. Therefore, this study assessed the effects of ALA on AGEs-induced GCs hormonal dysfunction.

Methods

The study was conducted from October 2021 to September 2022 at the Department of Medical Genetics, Shiraz University of Medical Sciences. Isolated GCs (n=50) were divided into control, human glycated albumin (HGA), HGA+ALA, and ALA treatments. Steroidogenic enzymes and AGE receptor (RAGE) genes were assessed by qRT-PCR. Steroid hormones and RAGE protein were evaluated using ELISA and Western blotting. Data were analyzed using GraphPad Prism software (ver. 9), and P<0.05 was considered significant.

Results

Our findings showed that HGA treatment significantly (P=0.0001) increased RAGE (by 140.66%), STAR (by 117.65%), 3β-HSD (by 165.68%), and 17β-HSD (by 122.15%) expression, while it decreased CYP19A1 (by 68.37%) expression. RAGE protein level (by 267.10%) was also increased in HGA-treated GCs. A significant decrease in estradiol (by 59.66%) and a slight and sharp elevation in progesterone (by 30.40%) and total testosterone (by 158.24%) levels was also observed. ALA treatment ameliorated the HGA-induced changes in steroidogenic enzyme mRNA levels (P=0.001) and steroid hormone secretion (P=0.010).

Conclusion

This work shows that ALA therapy likely corrects hormonal dysfunctions caused by AGEs in luteinized GCs. This effect is probably achieved by decreased RAGE expression. Clinical research is needed to understand how AGEs and ALA interact in the ovary, which might lead to a more targeted ovarian dysfunction therapy.

Development of an Endoplasmic Reticulum Stress-Related Diagnostic Signature in Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) is a prevalent endocrine and metabolic disorder in premenopausal women. This investigation was to elucidate the underlying mechanism of endoplasmic reticulum stress (ERS) activation in granulosa cells, which has been implicated in the etiology of PCOS. Differentially expressed genes (DEGs) between PCOS and control groups were integrated with ERS gene lists from databases to identify DE-ERS genes, and functional analyses were performed. Univariate regression analysis and the LASSO method were used to select diagnostic factors, followed by establishing a DE-ERS gene-based diagnostic model. A nomogram model was further generated to predict the risk of PCOS. The correlation between ERS gene expression and immune cell proportion was assessed. A total of 14 DE-ERS genes associated with "protein processing in endoplasmic reticulum", "ferroptosis", and "glycerophospholipid metabolism" were selected as PCOS-related factors. An eight-DE-ERS genes-based diagnostic model was developed and displayed satisfactory performance in the training (Area under curve (AUC) = 0.983) and validation datasets (AUC = 0.802). High risk of PCOS can be accurately predicted, which might contribute to clinical decision-making. Moreover, EDEM1 expression was significantly positively correlated with naive B cell infiltration, while PDIA6 was negatively correlated with neutrophil proportion (P < 0.001). We identified eight novel molecules and developed an ERS gene-based diagnostic model in PCOS, which might provide novel insight for finding biomarkers and treatment methods.

Mesencephalic astrocyte-derived neurotrophic factor ameliorates inflammatory response in polycystic ovary syndrome via inhibiting TLR4-NF-κB-NLRP3 pathway

Polycystic ovary syndrome (PCOS) is a common reproductive endocrine disorder in women of reproductive age, which often leads to female infertility. Chronic inflammation is a significant factor in the development of PCOS. Our study aimed to explore the impact of mesencephalic astrocyte-derived neurotrophic factor (MANF), a scientifically validated anti-inflammatory factor, on 99 diagnosed PCOS patients. We also investigated its effects on PCOS mice induced with dehydroepiandrosterone (DHEA) and KGN cells induced with dihydrotestosterone (DHT). Our findings revealed a decrease in serum MANF levels in PCOS patients, which were negatively associated with serum tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) levels. The administration of recombinant human MANF (rhMANF) in PCOS mice demonstrated a decrease in pro-inflammatory cytokines and monocytes/macrophages in both peripheral blood and ovarian tissues. Furthermore, the inclusion of rhMANF notably ameliorated DHEA-induced ovarian dysfunction and fibrosis by negatively regulating the toll-like receptor 4 (TLR4)-nuclear factor kappa B (NF-κB)-NLR family, pyrin domain containing protein 3 (NLRP3) pathway. Additionally, in vitro experiments showed that the up-regulation of MANF offset DHT-induced inhibition of viability and apoptosis in KGN cells. Collectively, this study highlights the anti-inflammatory properties of MANF in PCOS and suggests its potential as a therapeutic approach for the management of PCOS.

Cellular senescence of granulosa cells in the pathogenesis of polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is one of the most common endocrine disorders in women of reproductive age, but its pathology has not been fully characterized and the optimal treatment strategy remains unclear. Cellular senescence is a permanent state of cell-cycle arrest that can be induced by multiple stresses. Senescent cells contribute to the pathogenesis of various diseases, owing to an alteration in secretory profile, termed 'senescence-associated secretory phenotype' (SASP), including with respect to pro-inflammatory cytokines. Senolytics, a class of drugs that selectively eliminate senescent cells, are now being used clinically, and a combination of dasatinib and quercetin (DQ) has been extensively used as a senolytic. We aimed to investigate whether cellular senescence is involved in the pathology of PCOS and whether DQ treatment has beneficial effects in patients with PCOS. We obtained ovaries from patients with or without PCOS, and established a mouse model of PCOS by injecting dehydroepiandrosterone. The expression of the senescence markers p16INK4a, p21, p53, γH2AX, and senescence-associated β-galactosidase and the SASP-related factor interleukin-6 was significantly higher in the ovaries of patients with PCOS and PCOS mice than in controls. To evaluate the effects of hyperandrogenism and DQ on cellular senescence in vitro, we stimulated cultured human granulosa cells (GCs) with testosterone and treated them with DQ. The expression of markers of senescence and a SASP-related factor was increased by testosterone, and DQ reduced this increase. DQ reduced the expression of markers of senescence and a SASP-related factor in the ovaries of PCOS mice and improved their morphology. These results indicate that cellular senescence occurs in PCOS. Hyperandrogenism causes cellular senescence in GCs in PCOS, and senolytic treatment reduces the accumulation of senescent GCs and improves ovarian morphology under hyperandrogenism. Thus, DQ might represent a novel therapy for PCOS.

Oocyte quality is impaired in a hyperandrogenic PCOS mouse model by increased Foxo1 expression

One of the most important characteristics of patients with polycystic ovary syndrome (PCOS) is excess androgen, which has adverse effects on pregnancy outcomes and increases the risk of offspring developing metabolic disorders. Foxo1 has been shown to play an important role in PCOS, but whether it has an affect on oocyte's quality in PCOS remains unclear. The current research investigated the effect of excess androgen exposure on mouse oocyte quality, as well as the possible molecular mechanism. Timelapse incubator was used to culture oocytes in vitro and evaluate the maturation process. The level of reactive oxygen species (ROS) and mitochondrial membrane potential were detected by laser confocal microscope. Immunofluorescence staining assays were performed to examine the expression of Foxo1 and γ-H2AX. Relative mRNA level of Foxo1 and Caspase3 were examined by RT-qPCR. Results showed Germinal vesicle breakdown and maturation rates of oocytes from hyperandrogenic PCOS mice were significantly decreased in vitro, while in vitro maturation showed a marked delay from the germinal vesicle breakdown to metaphase II stage in PCOS group. Expression levels of reactive oxygen species, Foxo1, Caspase3, and γ-H2AX were significantly increased, whereas mitochondrial membrane potential was significantly decreased in oocytes from PCOS mice. These results indicate that excess androgen exposure induced oxidative stress, which further induced high expression of Foxo1, resulting in more DNA damage and apoptosis in oocytes. The current findings provide new knowledge for exploring the mechanism of decreased oocyte quality in hyperandrogenic PCOS.

Pathophysiological Effects of Contemporary Lifestyle on Evolutionary-Conserved Survival Mechanisms in Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) is increasingly being characterized as an evolutionary mismatch disorder that presents with a complex mixture of metabolic and endocrine symptoms. The Evolutionary Model proposes that PCOS arises from a collection of inherited polymorphisms that have been consistently demonstrated in a variety of ethnic groups and races. In utero developmental programming of susceptible genomic variants are thought to predispose the offspring to develop PCOS. Postnatal exposure to lifestyle and environmental risk factors results in epigenetic activation of developmentally programmed genes and disturbance of the hallmarks of health. The resulting pathophysiological changes represent the consequences of poor-quality diet, sedentary behaviour, endocrine disrupting chemicals, stress, circadian disruption, and other lifestyle factors. Emerging evidence suggests that lifestyle-induced gastrointestinal dysbiosis plays a central role in the pathogenesis of PCOS. Lifestyle and environmental exposures initiate changes that result in disturbance of the gastrointestinal microbiome (dysbiosis), immune dysregulation (chronic inflammation), altered metabolism (insulin resistance), endocrine and reproductive imbalance (hyperandrogenism), and central nervous system dysfunction (neuroendocrine and autonomic nervous system). PCOS can be a progressive metabolic condition that leads to obesity, gestational diabetes, type two diabetes, metabolic-associated fatty liver disease, metabolic syndrome, cardiovascular disease, and cancer. This review explores the mechanisms that underpin the evolutionary mismatch between ancient survival pathways and contemporary lifestyle factors involved in the pathogenesis and pathophysiology of PCOS.

Roles of endoplasmic reticulum stress in the pathophysiology of polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is the most common endocrine disorder among reproductive-age women, affecting up to 15% of women in this group, and the most common cause of anovulatory infertility. Although its etiology remains unclear, recent research has revealed the critical role of endoplasmic reticulum (ER) stress in the pathophysiology of PCOS. ER stress is defined as a condition in which unfolded or misfolded proteins accumulate in the ER because of an imbalance in the demand for protein folding and the protein-folding capacity of the ER. ER stress results in the activation of several signal transduction cascades, collectively termed the unfolded protein response (UPR), which regulates various cellular activities. In principle, the UPR restores homeostasis and keeps the cell alive. However, if the ER stress cannot be resolved, it induces programmed cell death. ER stress has recently been recognized to play diverse roles in both physiological and pathological conditions of the ovary. In this review, we summarize current knowledge of the roles of ER stress in the pathogenesis of PCOS. ER stress pathways are activated in the ovaries of both a mouse model of PCOS and in humans, and local hyperandrogenism in the follicular microenvironment associated with PCOS is responsible for activating these. The activation of ER stress contributes to the pathophysiology of PCOS through multiple effects in granulosa cells. Finally, we discuss the potential for ER stress to serve as a novel therapeutic target for PCOS.

Modulation of the Inflammatory Response in Polycystic Ovary Syndrome (PCOS)-Searching for Epigenetic Factors

Polycystic ovary syndrome (PCOS) is the most common endocrine disorder in women of reproductive age. Despite its incidence, the syndrome is poorly understood and remains underdiagnosed, and female patients are diagnosed with a delay. The heterogenous nature of this complex disorder results from the combined occurrence of genetic, environmental, endocrine, and behavioral factors. Primary clinical manifestations of PCOS are derived from the excess of androgens (anovulation, polycystic ovary morphology, lack of or scanty, irregular menstrual periods, acne and hirsutism), whereas the secondary manifestations include multiple metabolic, cardiovascular, and psychological disorders. Dietary and lifestyle factors play important roles in the development and course of PCOS, which suggests strong epigenetic and environmental influences. Many studies have shown a strong association between PCOS and chronic, low-grade inflammation both in the ovarian tissue and throughout the body. In the vast majority of PCOS patients, elevated values of inflammatory markers or their gene markers have been reported. Development of the vicious cycle of the chronic inflammatory state in PCOS is additionally stimulated by hyperinsulinemia and obesity. Changes in DNA methylation, histone acetylation and noncoding RNA levels are presented in this review in the context of oxidative stress, reactive oxygen species, and inflammatory signaling in PCOS. Epigenetic modulation of androgenic activity in response to inflammatory signaling is also discussed.

Contribution of Advanced Glycation End Products to PCOS Key Elements: A Narrative Review

In the last decade, data has suggested that dietary advanced glycation end products (AGEs) play an important role in both reproductive and metabolic dysfunctions associated with polycystic ovary syndrome (PCOS). AGEs are highly reactive molecules that are formed by the non-enzymatic glycation process between reducing sugars and proteins, lipids, or nucleic acids. They can be formed endogenously under normal metabolic conditions or under abnormal situations such as diabetes, renal disease, and other inflammatory disorders. Bodily AGEs can also accumulate from exogenous dietary sources particularly when ingested food is cooked and processed under high-temperature conditions, such as frying, baking, or grilling. Women with PCOS have elevated levels of serum AGEs that are associated with insulin resistance and obesity and that leads to a high deposition of AGEs in the ovarian tissue causing anovulation and hyperandrogenism. This review will describe new data relevant to the role of AGEs in several key elements of PCOS phenotype and pathophysiology. Those elements include ovarian dysfunction, hyperandrogenemia, insulin resistance, and obesity. The literature findings to date suggest that targeting AGEs and their cellular actions could represent a novel approach to treating PCOS symptoms.

Potential role of endoplasmic reticulum stress in the pathophysiology of polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is an endocrine disorder that affects million women worldwide, presenting a complex pathophysiology that has not been fully elucidated yet. Recently, it has been suggested that PCOS triggers the endoplasmic reticulum (ER) stress, thus being associated with unfolded protein response (UPR) activation. Indeed, the UPR response has been associated with several pathological conditions, including in the reproductive system. Several studies demonstrated that ovarian UPR markers are upregulated in PCOS, being associated with worst ovarian outcomes, and this was ameliorated by ER stress inhibition. In this review, we aim to summarize the main findings from previous studies covering this topic, in an attempt to clarify the potential role of ER stress and the UPR response in the pathophysiology of PCOS.

Notch Signaling Induced by Endoplasmic Reticulum Stress Regulates Cumulus-Oocyte Complex Expansion in Polycystic Ovary Syndrome

Endoplasmic reticulum (ER) stress activated in granulosa cells contributes to the pathophysiology of polycystic ovary syndrome (PCOS). In addition, recent studies have demonstrated that Notch signaling plays multiple roles in the ovary via cell-to-cell interactions. We hypothesized that ER stress activated in granulosa cells of antral follicles in PCOS induces Notch signaling in these cells, and that activated Notch signaling induces aberrant cumulus-oocyte complex (COC) expansion. Expression of Notch2 and Notch-target transcription factors was increased in granulosa cells of PCOS patients and model mice. ER stress increased expression of Notch2 and Notch-target transcription factors in cultured human granulosa-lutein cells (GLCs). Inhibition of Notch signaling abrogated ER stress-induced expression of genes associated with COC expansion in cultured human GLCs, as well as ER stress-enhanced expansion of cumulus cells in cultured murine COCs. Furthermore, inhibition of Notch signaling reduced the areas of COCs in PCOS model mice with activated ER stress in the ovary, indicating that Notch signaling regulates COC expansion in vivo. Our findings suggest that Notch2 signaling is activated in granulosa cells in PCOS and regulates COC expansion. It remains to be elucidated whether aberrant COC expansion induced by the ER stress-Notch pathway is associated with ovulatory dysfunction in PCOS patients.

Targeted metabolomics analysis of bile acids and cell biology studies reveal the critical role of glycodeoxycholic acid in buffalo follicular atresia

The follicular fluid of mammals has a high abundance of bile acids and these have proven to be closely related to the follicular atresia. However, the origin and content of bile acids in follicular fluid and its mechanisms on follicular atresia remain largely unknown. In this work, we analyzed the origin of bile acids in buffalo follicles by using cell biology studies, and quantified the subspecies of bile acids in follicular fluid from healthy follicles (HF) and atretic follicles (AF) by targeted metabolomics. The function of differential bile acids on follicular granulosa cells was also studied. The results showed that the bile acids transporters were abundantly expressed in ovarian tissues, but the rate-limiting enzymes were not, which was consistent with the inability of cultured follicular cells to convert cholesterol into bile acids. Targeted metabolomics analysis revealed thirteen differential subspecies of bile acids between HF and AF. The free bile acids were significant down-regulated and their conjugated forms were significantly up-regulated in AF as compared to HF. Finally, cell biological validation found a specific differentially conjugated bile acid, glycodeoxycholic acid (GDCA), which could promote follicular granulosa cell apoptosis and reduce steroid hormone secretion. In summary, our studies suggest that bile acids in buffalo follicles are transported from the blood rather than being synthesized within the follicles. The conjugated bile acids such as GDCA, accumulate in buffalo follicles, and may accelerate atresia by promoting apoptosis of granulosa cells and inhibiting steroid hormone production. These results will provide new clues for studying the physiological role and mechanism of bile acids involved in buffalo follicular atresia.

Metabolic and Molecular Mechanisms of Diet and Physical Exercise in the Management of Polycystic Ovarian Syndrome

Polycystic ovary syndrome (PCOS) is an endocrine systemic disorder mainly characterized by a hormonal and metabolic disbalance that leads to oligo/anovulation, hyperandrogenism and the formation of ovarian cysts. Despite the progress that has been reached in its diagnosis and management, little is known about the molecular mechanisms and signaling pathways underlying the pathogenic mechanisms. In this sense, recent research has suggested that the influence of multiple factors, including age, environment, lifestyle and the disease state environment can change the clinical presentation of PCOS via epigenetic modifications. Variants in the genes encoding for proteins involved in steroidogenesis and glucose homeostasis play a crucial role in the development of the disease. Other genes involved in inflammation and cell proliferation seem to undergo an epigenetic control. Moreover, lifestyle factors influence the PCOS course and prognosis, including diet and physical activity, which are fundamental in reducing oxidative stress, inflammation and in improving metabolic and hormonal parameters. In the present review, literature evidence on molecular and epigenetic mechanisms related to PCOS etiology will be discussed, with a particular attention on the positive influence of diet and physical activity as nonpharmacological ways of intervention in the management of the disease.

Advanced Glycation End-Products (AGEs): Formation, Chemistry, Classification, Receptors, and Diseases Related to AGEs

Advanced glycation end-products (AGEs) constitute a non-homogenous, chemically diverse group of compounds formed either exogeneously or endogeneously on the course of various pathways in the human body. In general, they are formed non-enzymatically by condensation between carbonyl groups of reducing sugars and free amine groups of nucleic acids, proteins, or lipids, followed by further rearrangements yielding stable, irreversible end-products. In the last decades, AGEs have aroused the interest of the scientific community due to the increasing evidence of their involvement in many pathophysiological processes and diseases, such as diabetes, cancer, cardiovascular, neurodegenerative diseases, and even infection with the SARS-CoV-2 virus. They are recognized by several cellular receptors and trigger many signaling pathways related to inflammation and oxidative stress. Despite many experimental research outcomes published recently, the complexity of their engagement in human physiology and pathophysiological states requires further elucidation. This review focuses on the receptors of AGEs, especially on the structural aspects of receptor-ligand interaction, and the diseases in which AGEs are involved. It also aims to present AGE classification in subgroups and to describe the basic processes leading to both exogeneous and endogeneous AGE formation.

Endoplasmic Reticulum Stress: A New Research Direction for Polycystic Ovary Syndrome?

Polycystic ovary syndrome (PCOS) is one of the most common gynecological endocrine disorders, with sporadic ovulation, excessive androgens, and polycystic ovarian changes as the main clinical manifestations. Due to the high heterogeneity of its clinical manifestations, the discussion on its pathogenesis has not been unified. Current research has found that genetic factors, hyperandrogenism, chronic inflammation and oxidative stress, insulin resistance, and obesity are strongly associated with PCOS. Recently, when studying the specific mechanisms of the abovementioned factors in PCOS, the biological response process of endoplasmic reticulum stress (ERS) has gradually come to researchers' attention, and several studies have confirmed the involvement of ERS in the pathogenesis of PCOS and the improvement of a series of pathological manifestations of PCOS after the application of ERS inhibitors, which may be a new entry point for the treatment of PCOS. In this article, we review the relationship between ERS and various pathogenic factors of PCOS.

Knockdown of DPP4 promotes the proliferation and the activation of the CREB/aromatase pathway in ovarian granulosa cells

Dipeptidyl peptidase 4 (DPP4) has been revealed to be upregulated in women suffering from polycystic ovary syndrome (PCOS), which is a common reproductive disorder. The present study was designed to investigate the effects of inhibition of DPP4 expression on the proliferation of ovarian granulosa cells as well as on the activation of the cAMP response element‑binding protein (CREB)/aromatase pathway. The expression levels of DPP4 in rat serum samples with or without PCOS and ovarian granulosa cells (KGN cells) were detected using reverse transcription‑quantitative PCR (RT‑qPCR) and western blot analyses. Cell viability and cell cycle progression were detected using the Cell Counting Kit‑8 assay and flow cytometric analysis, respectively. The 5‑ethynyl‑2'‑deoxyuridine assay was employed to detect the proliferation of glycolaldehyde‑bovine serum albumin (GOA‑BSA)‑treated KGN cells. In addition, RT‑qPCR and western blot analyses were applied to detect the expression levels of CREB, specific cell cycle‑associated proteins and cytochrome P450 (CYP) 19A1 and CYP11A1 enzymes in KGN cells. The expression levels of DPP4 were upregulated in rats with PCOS. Inhibition of DPP4 expression promoted the proliferation and cell cycle arrest of KGN cells. It was also revealed that the expression levels of cell cycle‑associated proteins were upregulated in DPP4‑silenced KGN cells. In addition, their proliferation was decreased following treatment with GOA‑BSA, while the addition of sitagliptin partially reversed these effects. Additionally, sitagliptin reversed the inhibitory effects caused by GOA‑BSA treatment on the cell cycle progression and on the activation of the CREB/aromatase pathway in KGN cells, as determined by the increased expression levels of the cell cycle‑associated proteins as well as those of the CREB protein and the CYP19A1 and CYP11A1 enzymes. In conclusion, inhibition of DPP4 expression promoted the proliferation of KGN cells and the activation of the CREB/aromatase pathway.

Comprehensive Assessment of the STIMs and Orais Expression in Polycystic Ovary Syndrome

BACKGROUND

Polycystic ovary syndrome (PCOS) is a heterogeneous endocrine disease characterized by irregular menstrual, hyperandrogenism, and polycystic ovaries. The definitive mechanism of the disorder is not fully elucidated. Store-operated Ca2+ entry (SOCE) plays a role in glucose and lipid metabolism, inflammation, hormone secretion, and cell proliferation. STIMs and Orais are the main elements of SOCE. The potential role of SOCE in PCOS pathogenesis remains unclear.

METHODS

The expression of STIMs and Orais in granulosa cells (GCs) derived from 83 patients with PCOS and 83 controls were analyzed, respectively, by using quantitative reverse transcription polymerase chain reaction. Binary regression analysis was used to identify the factors affecting PCOS after adjusted by body mass index and age. Pearson correlation analysis was used to determine the association between PCOS phenotypes and SOCE genes expression.

RESULTS

Significantly increased expression of STIM1, STIM2, Orai1, and Orai2 were observed in patients with PCOS compared with controls (P = 0.037, P = 0.004, P ≤ 0.001, and P = 0.013, respectively), whereas the expression of Orai3 was decreased (P = 0.003). In addition, the expression levels of STIMs and Orais were identified as the factors affecting PCOS (P < 0.05). The expressions of these genes were correlated with hormone level and antral follicle count (P < 0.05).

CONCLUSIONS

For the first time, our findings indicated that the elements of SOCE were differently expressed, where STIM1, STIM2, Orai1, and Orai2 significantly increased, whereas Orai3 decreased in PCOS GCs, which might be dominantly involved in dysfunction of ovarian GCs and hormonal changes in PCOS.

Pathophysiology of polycystic ovary syndrome revisited: Current understanding and perspectives regarding future research

Background

Polycystic ovary syndrome (PCOS) is the most common endocrine disorder among reproductive-age women and has lifelong effects on health.

Methods

In this review, I discuss the pathophysiology of PCOS. First, I summarize our current understanding of the etiology and pathology of PCOS, then, discuss details of two representative environmental factors involved in the pathogenesis of PCOS. Finally, I present perspectives regarding the directions of future research.

Main findings

The pathophysiology of PCOS is heterogeneous and shaped by the interaction of reproductive dysfunction and metabolic disorders. Hyperandrogenism and insulin resistance exacerbate one another during the development of PCOS, which is also affected by dysfunction of the hypothalamus-pituitary-ovarian axis. PCOS is a highly heritable disorder, and exposure to certain environmental factors causes individuals with predisposing genetic factors to develop PCOS. The environmental factors that drive the development of PCOS pathophysiology make a larger contribution than the genetic factors, and may include the intrauterine environment during the prenatal period, the follicular microenvironment, and lifestyle after birth.

Conclusion

On the basis of this current understanding, three areas are proposed to be subjects for future research, with the ultimate goals of developing therapeutic and preventive strategies and providing appropriate lifelong management, including preconception care.

Effects of Androgen Excess-Related Metabolic Disturbances on Granulosa Cell Function and Follicular Development

Polycystic ovary syndrome (PCOS) is a common reproductive endocrine disease in women of reproductive age. Ovarian dysfunction including abnormal steroid hormone synthesis and follicular arrest play a vital role in PCOS pathogenesis. Hyperandrogenemia is one of the important characteristics of PCOS. However, the mechanism of regulation and interaction between hyperandrogenism and ovulation abnormalities are not clear. To investigate androgen-related metabolic state in granulosa cells of PCOS patients, we identified the transcriptome characteristics of PCOS granulosa cells by RNA-seq. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis of differentially expressed genes (DEGs) revealed that genes enriched in lipid metabolism pathway, fatty acid biosynthetic process and ovarian steroidogenesis pathway were abnormally expressed in PCOS granulosa cells in comparison with that in control. There are close interactions among these three pathways as identified by analysis of the protein-protein interaction (PPI) network of DEGs. Furthermore, in vitro mouse follicle culture system was established to explore the effect of high androgen and its related metabolic dysfunction on follicular growth and ovulation. RT-qPCR results showed that follicles cultured with dehydroepiandrosterone (DHEA) exhibited decreased expression levels of cumulus expansion-related genes (Has2, Ptx3, Tnfaip6 and Adamts1) and oocyte maturation-related genes (Gdf9 and Bmp15), which may be caused by impaired steroid hormone synthesis and lipid metabolism, thus inhibited follicular development and ovulation. Furthermore, the inhibition effect of DHEA on follicle development and ovulation was ameliorated by flutamide, an androgen receptor (AR) antagonist, suggesting the involvement of AR signaling. In summary, our study offers new insights into understanding the role of androgen excess induced granulosa cell metabolic disorder in ovarian dysfunction of PCOS patients.

Molecular mechanism of dihydropyrazine-induced cytotoxicity: the possibility of an independent pathway from the receptor for advanced glycation end products

Dihydropyrazines (DHPs) are one of glycation products that are non-enzymatically generated in vivo and in food. We had previously revealed that 3-hydro-2,2,5,6-tetramethylpyrazine (DHP-3), a methyl-substituted DHP, elicited redox imbalance and cytotoxicity in cultured cells. However, the molecular mechanisms underlying DHP-3-induced cytotoxicity remain unclear. To address this issue, we examined the involvement of the receptor for advanced glycation end products (RAGE) in DHP-3-induced cytotoxicity. To evaluate the role of RAGE, we prepared HeLa cells that constitutively expressed RAGE and its deletion mutant, which lacks the cytoplasmic domain (RAGE_Δcyto), using an episomal vector. After transfection with the vector, cells were selected following incubation with multiple concentrations of hygromycin to remove non-transfected cells. The expression of RAGE and RAGE_Δcyto in the cells was confirmed by immunoblotting. RAGE and RAGE_Δcyto were apparently expressed in transfected cells; however, there were no significant differences in DHP-3-induced cytotoxicity between these cells and mock vector-transfected cells. These results suggested that DHP-3 elicits cytotoxicity in a RAGE-independent manner.

MiR-1224-5p attenuates polycystic ovary syndrome through inhibiting NOD-like receptor protein 3 inflammasome activation via targeting Forkhead box O 1

Polycystic ovary syndrome (PCOS) is a common endocrine disorder that poses a great threat to women's health. MiR-1224-5p is downregulated in the follicular fluid of patients with PCOS, but its role remains largely unknown. In this study, mice were treated with dehydroepiandrosterone (DHEA) to establish an in vivo model of PCOS. We found that enhanced activation of NLRP3 inflammasome was accompanied by downregulation of miR-1224-5p in ovarian tissue of PCOS mice. The effect of miR-1224-5p was further explored in TNF-α-treated human granulosa-like tumor (KGN) cells. Upregulation of miR-1224-5p suppressed TNF-α-induced secretion of DHEA and testosterone. MiR-1224-5p attenuated TNF-α-induced inflammation by inhibiting NLRP3 inflammasome activation, IL-1β synthesis, and nuclear factor kappa B (NF-κB) p65 nuclear translocation. Notably, miR-1224-5p decreased the expression of Forkhead box O 1 (FOXO1) and its downstream gene thioredoxin interaction protein (TXNIP). Luciferase reporter assay confirmed FOXO1 as a target of miR-1224-5p. Upregulation of FOXO1 abolished miR-1224-5p-induced activation of NLRP3 inflammasome, demonstrating that miR-1224-5p might inhibit NLRP3 inflammasome activation through regulating FOXO1. This study provided novel insights into the pathogenesis of PCOS and suggested that miR-1224-5p might be a promising target for treating PCOS.

Luteinizing Hormone Regulation of Inter-Organelle Communication and Fate of the Corpus Luteum

The corpus luteum is an endocrine gland that synthesizes the steroid hormone progesterone. luteinizing hormone (LH) is a key luteotropic hormone that stimulates ovulation, luteal development, progesterone biosynthesis, and maintenance of the corpus luteum. Luteotropic and luteolytic factors precisely regulate luteal structure and function; yet, despite recent scientific progress within the past few years, the exact mechanisms remain largely unknown. In the present review, we summarize the recent progress towards understanding cellular changes induced by LH in steroidogenic luteal cells. Herein, we will focus on the effects of LH on inter-organelle communication and steroid biosynthesis, and how LH regulates key protein kinases (i.e., AMPK and MTOR) responsible for controlling steroidogenesis and autophagy in luteal cells.

Inflammatory cytokines as key players of apoptosis induced by environmental estrogens in the ovary

Natural and synthetic environmental estrogens (EEs), interfering with the physiological functions of the body's estrogens, are widespread and are rising much concern for their possible deleterious effects on human and animal health, in particular on reproduction. In fact, increasing evidence indicate that EEs can be responsible for a variety of disfunctions of the reproductive system especially in females such as premature ovarian insufficiency (POI). Because of their great structural diversity, the modes of action of EEs are controversial. One important way through which EEs exert their effects on reproduction is the induction of apoptosis in the ovary. In general, EEs can exert pro-and anti-apoptotic effects by agonizing or antagonizing numerous estrogen-dependent signaling pathways. In the present work, results concerning apoptotic pathways and diseases induced by representative EEs (such as zearalenone, bisphenol A and di-2-ethylhexyl phthalate), in ovaries throughout development are presented into an integrated network. By reviewing and elaborating these studies, we propose inflammatory factors, centered on the production of tumor necrosis factor (TNF), as a major cause of the induction of apoptosis by EEs in the mammalian ovary. As a consequence, potential strategies to prevent such EE effect are suggested.

Resveratrol and endoplasmic reticulum stress: A review of the potential protective mechanisms of the polyphenol

The endoplasmic reticulum (ER) is an organelle that performs a set of essential functions in cellular biology. These include synthesis of lipids, homeostasis of calcium, and controlling the folding of proteins. Inflammation and oxidative stress are two important reasons behind the accumulation of misfolded or unfolded proteins in the ER. In such circumstances, a series of measures are undertaken in the cell which are collectively called unfolded protein response (UPR). The aim of UPR is to reduce the burden of protein aggregates and promote survival. However, extended and unrestricted ER stress (ERS) can induce further inflammation and apoptosis. ERS and the UPR are involved in different diseases such as neurodegenerative and cardiovascular diseases. Resveratrol (RSV), a natural polyphenol, has well-documented evidence supporting its numerous biological properties including antioxidant, antiinflammatory, antiobesity, antidiabetic, and antiischemic activities. The compound is also known for its potential beneficial effects on cognitive function and liver, kidney, and lung health. In this review, the role of ERS in several pathological conditions and the potential protective effects of RSV are discussed. However, the scarcity of clinical data means that more research needs to be conducted to gain a lucid understanding of RSV's effects on endoplasmic reticulum stress (ERS) in humans.

TMT-based proteomic and bioinformatic analyses of human granulosa cells from obese and normal-weight female subjects

BACKGROUND

Increasing evidence supports a relationship between obesity and either infertility or subfertility in women. Most previous omics studies were focused on determining if the serum and follicular fluid expression profiles of subjects afflicted with both obesity-related infertility and polycystic ovary syndrome (PCOS) are different than those in normal healthy controls. As granulosa cells (GCs) are essential for oocyte development and fertility, we determined here if the protein expression profiles in the GCs from obese subjects are different than those in their normal-weight counterpart.

METHODS

GC samples were collected from obese female subjects (n = 14) and normal-weight female subjects (n = 12) who were infertile and underwent in vitro fertilization (IVF) treatment due to tubal pathology. A quantitative approach including tandem mass tag labeling and liquid chromatography tandem mass spectrometry (TMT) was employed to identify differentially expressed proteins. Gene Ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were then conducted to interrogate the functions and pathways of identified proteins. Clinical, hormonal, and biochemical parameters were also analyzed in both groups.

RESULTS

A total of 228 differentially expressed proteins were noted, including 138 that were upregulated whereas 90 others were downregulated. Significant pathways and GO terms associated with protein expression changes were also identified, especially within the mitochondrial electron transport chain. The levels of free fatty acids in both the serum and follicular fluid of obese subjects were significantly higher than those in matched normal-weight subjects.

CONCLUSIONS

In GCs obtained from obese subjects, their mitochondria were damaged and the endoplasmic reticulum stress response was accompanied by dysregulated hormonal synthesis whereas none of these changes occurred in normal-weight subjects. These alterations may be related to the high FFA and TG levels detected in human follicular fluid.

Androgens impair β-cell function in a mouse model of polycystic ovary syndrome by activating endoplasmic reticulum stress

BACKGROUND

Androgens excess results in endoplasmic reticulum (ER) stress, which is an important cause of β cells dysfunction. Here, we investigated the molecular regulation of androgens excess, ER stress, and β-cell function in polycystic ovary syndrome (PCOS).

METHODS

PCOS mouse model was established by injection of DHEA. Primary cultured mouse islets were used to detect testosterone (TE)-induced ER stress. The response of ER stress, apoptosis, and hyperinsulinemia were analyzed in INS-1 cells with or without TE exposure. Androgen receptor (AR) antagonist and ER stress inhibitor treatment was performed to evaluate the role of TE in ER stress and proinsulin secretion of PCOS mice.

RESULTS

PCOS mice had higher ER stress in islets. TE exposure induced ER stress and apoptosis significantly through sustaining insulin overexpression in β cells, which in turn impaired proinsulin maturation and secretion. Blocking this process could significantly relieve ER stress and apoptosis and improve insulin homeostasis.

CONCLUSION

ER stress activated by androgens excess in PCOS contributes to β cell dysfunction and hyperinsulinemia.

Induction of aryl hydrocarbon receptor in granulosa cells by endoplasmic reticulum stress contributes to pathology of polycystic ovary syndrome

Recent studies have uncovered the critical role of aryl hydrocarbon receptor (AHR) in various diseases, including obesity and cancer progression, independent of its previously identified role as a receptor for endocrine-disrupting chemicals (EDCs). We previously showed that endoplasmic reticulum (ER) stress, a newly recognized local factor in the follicular microenvironment, is activated in granulosa cells from patients with polycystic ovary syndrome (PCOS) and a mouse model of the disease. By affecting diverse functions of granulosa cells, ER stress contributes to PCOS pathology. We hypothesized that expression of AHR and activation of its downstream signaling were upregulated by ER stress in granulosa cells, irrespective of the presence of EDCs, thereby promoting PCOS pathogenesis. In this study, we found that AHR, AHR nuclear translocator (ARNT), and AHR target gene cytochrome P450 1B1 (CYP1B1) were upregulated in the granulosa cells of PCOS patients and model mice. We examined CYP1B1 as a representative AHR target gene. AHR and ARNT were upregulated by ER stress in human granulosa-lutein cells (GLCs), resulting in an increase in the expression and activity of CYP1B1. Administration of the AHR antagonist CH223191 to PCOS mice restored estrous cycling and decreased the number of atretic antral follicles, concomitant with downregulation of AHR and CYP1B1 in granulosa cells. Taken together, our findings indicate that AHR activated by ER stress in the follicular microenvironment contributes to PCOS pathology, and that AHR represents a novel therapeutic target for PCOS.

Endoplasmic reticulum stress: a key regulator of the follicular microenvironment in the ovary

Intra-ovarian local factors regulate the follicular microenvironment in coordination with gonadotrophins, thus playing a crucial role in ovarian physiology as well as pathological states such as polycystic ovary syndrome (PCOS). One recently recognized local factor is endoplasmic reticulum (ER) stress, which involves the accumulation of unfolded or misfolded proteins in the ER related to various physiological and pathological conditions that increase the demand for protein folding or attenuate the protein-folding capacity of the organelle. ER stress results in activation of several signal transduction cascades, collectively termed the unfolded protein response (UPR), which affect a wide variety of cellular functions. Recent studies have revealed diverse roles of ER stress in physiological and pathological conditions in the ovary. In this review, we summarize the most current knowledge of the regulatory roles of ER stress in the ovary, in the context of reproduction. The physiological roles of ER stress and the UPR in the ovary remain largely undetermined. On the contrary, activation of ER stress is known to impair follicular and oocyte health in various pathological conditions; moreover, ER stress also contributes to the pathogenesis of several ovarian diseases, including PCOS. Finally, we discuss the potential of ER stress as a novel therapeutic target. Inhibition of ER stress or UPR activation, by treatment with existing chemical chaperones, lifestyle intervention, or the development of small molecules that target the UPR, represents a promising therapeutic strategy.

FPS-ZM1 Alleviates Neuroinflammation in Focal Cerebral Ischemia Rats via Blocking Ligand/RAGE/DIAPH1 Pathway

Receptor for advanced glycation end products (RAGEs), a multiligand receptor belonging to the cell-surface immunoglobulin superfamily, has been reported to play a crucial role in neuroinflammation and neurodegenerative diseases. Here, we tested our hypothesis that the RAGE-specific antagonist FPS-ZM1 is neuroprotective against ischemic brain injury. Distal middle cerebral artery occlusion (MCAO) or sham operation was performed on anesthetized Sprague-Dawley male rats (n = 60), which were then treated with FPS-ZM1 or vehicle (four groups in total = Vehicle + MCAO, FPS-ZM1 + MCAO, Vehicle + sham, and FPS-ZM1 + sham). After 1 week, neurological function was evaluated, and then, brain tissues were collected for 2,3,5-triphenyltetrazolium chloride staining, Nissl staining, TUNEL staining, Western blotting, and immunohistochemical analyses. FPS-ZM1 treatment after MCAO markedly attenuated neurological deficits and reduced the infarct area. More interestingly, FPS-ZM1 inhibited ischemia-induced astrocytic activation and microgliosis and decreased the elevated levels of proinflammatory cytokines. Furthermore, FPS-ZM1 blocked the increase in the level of RAGE and, notably, of DIAPH1, the key cytoplasmic hub for RAGE-ligand-mediated activation of cellular signaling. Accordingly, FPS-ZM1 also reversed the MCAO-induced increase in phosphorylation of NF-κB targets that are potentially downstream from RAGE/DIAPH1. Our findings reveal that FPS-ZM1 treatment reduces neuroinflammation in rats with focal cerebral ischemia and further suggest that the ligand/RAGE/DIAPH1 pathway contributes to this FPS-ZM1-mediated alleviation of neuroinflammation.

The role of androgen and its related signals in PCOS

Polycystic ovary syndrome (PCOS) is the most common endocrine disorder in women at reproductive age. However, the underlying pathogenic mechanisms have not been completely understood. Hyperandrogenism is an important clinic feature in patients with PCOS, suggesting its pathologic role in the development and progression of PCOS. However, the actual role of androgen and the related signals in PCOS and PCOS-related complications have not yet been clarified. In this review, we surveyed the origin and effects of androgen on PCOS and the related complications, highlighted the cellular signals affecting androgen synthesis and summarized the pathological processes caused by hyperandrogenism. Our review well reveals the important mechanisms referring the pathogenesis of PCOS and provides important clues to the clinic strategies in patients with PCOS.

In Search of New Therapeutics-Molecular Aspects of the PCOS Pathophysiology: Genetics, Hormones, Metabolism and Beyond

In a healthy female reproductive system, a subtle hormonal and metabolic dance leads to repetitive cyclic changes in the ovaries and uterus, which make an effective ovulation and potential implantation of an embryo possible. However, that is not so in the case of polycystic ovary syndrome (PCOS), in which case the central mechanism responsible for entraining hormonal and metabolic rhythms during the menstrual cycle is notably disrupted. In this review we provide a detailed description of the possible scenario of PCOS pathogenesis. We begin from the analysis of how a set of genetic disorders related to PCOS leads to particular malfunctions at a molecular level (e.g., increased enzyme activities of cytochrome P450 (CYP) type 17A1 (17α-hydroxylase), 3β-HSD type II and CYP type 11A1 (side-chain cleavage enzyme) in theca cells, or changes in the expression of aquaporins in granulosa cells) and discuss further cellular- and tissue-level consequences (e.g., anovulation, elevated levels of the advanced glycation end products in ovaries), which in turn lead to the observed subsequent systemic symptoms. Since gene-editing therapy is currently out of reach, herein special emphasis is placed on discussing what kinds of drug targets and which potentially active substances seem promising for an effective medication, acting on the primary causes of PCOS on a molecular level.

Electroacupuncture alleviates polycystic ovary syndrome-like symptoms through improving insulin resistance, mitochondrial dysfunction, and endoplasmic reticulum stress via enhancing autophagy in rats

BACKGROUND

Electroacupuncture (EA), a treatment derived from traditional Chinese medicine, can effectively improve hyperandrogenism and insulin resistance in patients with polycystic ovary syndrome (PCOS), however, its underlying mechanisms remain obscure. This study aimed to investigate whether EA could mitigate PCOS-like symptoms in rats by regulating autophagy.

METHODS

A rat model of PCOS-like symptoms was established by subcutaneous injection with dehydroepiandrosterone (DHEA), and then EA treatment at acupoints (ST29 and SP6) was carried out for 5 weeks. To inhibit autophagy in rats, intraperitoneal injection with 0.5 mg/kg 3-MA (an autophagy inhibitor) was performed at 30 min before each EA treatment.

RESULTS

EA intervention alleviated PCOS-like symptoms in rats, which was partly counteracted by the combination with 3-MA. Moreover, DHEA-exposure-induced deficient autophagy in skeletal muscle was improved by EA treatment. EA-mediated improvements in insulin resistance, mitochondrial dysfunction, and endoplasmic reticulum (ER) stress in PCOS-like rats were counteracted by 3-MA pretreatment. Mechanically, EA attenuated autophagy deficiency-mediated insulin resistance in PCOS-like rats via inactivating mTOR/4E-BP1 signaling pathway.

CONCLUSIONS

Taken together, our findings indicate that EA treatment ameliorates insulin resistance, mitochondrial dysfunction, and ER stress through enhancing autophagy in a PCOS-like rat model. Our study provides novel insight into the mechanisms underlying the treatment of EA in PCOS, which offers more theoretic foundation for its clinical application.

The role of advanced glycation end products in human infertility

Advanced glycation end products (AGEs) are heterogeneous products of the non-enzymatic interaction between proteins and reducing sugars. Numerous studies have shown that AGEs are associated with senescence, diabetes, vascular disease, aging and kidney disease. Infertility has been affected approximately 10 to15% of couples of reproductive ages. AGEs accumulation has been shown to play a crucial role in pathogenesis of infertility-related diseases. The present review provides the generation process, mechanism and pathological significance of AGEs and the novel treatment targeting AGEs for infertility.