Melatonin attenuates palmitic acid-induced mouse granulosa cells apoptosis via endoplasmic reticulum stress

Effects of Melatonin and 3,5,3'-Triiodothyronine on the Development of Rat Granulosa Cells

Melatonin, as an endocrine neurotransmitter, can promote the development of the ovary. Meanwhile, it also has protective effect on the ovary as an antioxidant. Thyroid hormone (TH) is essential for normal human reproductive function. Many studies have shown that 3,5,3'-triiodothyronine (T3) regulates the development of ovarian granulosa cells. However, little is known about the specific mechanisms by which melatonin combines with T3 to regulate granulosa cell development. The aim of present study was to investigate the effects and the possible mechanisms of melatonin and T3 on ovarian granulosa cell development. In the present study, cell development and apoptosis were detected by CCK8, EdU and TUNEL, respectively. The levels of related proteins were analyzed by Western blotting. The results showed that oxidative stress (OS) and reactive oxygen species (ROS) were induced by H2O2 in granulosa cells, and cell apoptosis was also increased accompanied with the decreased cellular proliferation and viability. Melatonin protects granulosa cells from H2O2-induced apoptosis and OS by downregulating ROS levels, especially in the presence of T3. Co-treatment of cell with melatonin and T3 also promotes the expression of GRP78 and AMH, while inhibiting CHOP, Caspase-3, and P16. It was demonstrated that melatonin alone or in combination with T3 had positive effect on the development of granulosa cells. In addition, the AMPK/SIRT1 signaling pathway is involved in the process of melatonin/T3 promoting granulosa cell development.

Melatonin regulates endoplasmic reticulum stress in diverse pathophysiological contexts: A comprehensive mechanistic review

The endoplasmic reticulum (ER) is crucial for protein quality control, and disruptions in its function can lead to various diseases. ER stress triggers an adaptive response called the unfolded protein response (UPR), which can either restore cellular homeostasis or induce cell death. Melatonin, a safe and multifunctional compound, shows promise in controlling ER stress and could be a valuable therapeutic agent for managing the UPR. By regulating ER and mitochondrial functions, melatonin helps maintain cellular homeostasis via reduction of oxidative stress, inflammation, and apoptosis. Melatonin can directly or indirectly interfere with ER-associated sensors and downstream targets of the UPR, impacting cell death, autophagy, inflammation, molecular repair, among others. Crucially, this review explores the mechanistic role of melatonin on ER stress in various diseases including liver damage, neurodegeneration, reproductive disorders, pulmonary disease, cardiomyopathy, insulin resistance, renal dysfunction, and cancer. Interestingly, while it alleviates the burden of ER stress in most pathological contexts, it can paradoxically stimulate ER stress in cancer cells, highlighting its intricate involvement in cellular homeostasis. With numerous successful studies using in vivo and in vitro models, the continuation of clinical trials is imperative to fully explore melatonin's therapeutic potential in these conditions.

Melatonin alleviates endoplasmic reticulum stress to improve ovarian function by regulating the mTOR pathway in aged laying hens

Granular cell apoptosis is a key factor leading to follicular atresia and decreased laying rate in aged laying hens. Endoplasmic reticulum stress (ERS) induced cell apoptosis is a new type of apoptosis pathway. Previous studies have shown that the ERS pathway is involved in the regulation of follicular development and atresia, and can be regulated by mTOR. Melatonin (MEL) can protect the normal development of follicles, but the precise mechanism by which MEL regulates follicular development is not yet clear. So, we investigated the potential relationship between MEL and ERS and mTOR signaling pathway in vivo through intraperitoneal injection of MEL in aged laying hens. The results show that the laying rate, ovarian follicle number, plasma MEL, E2, LH, FSH concentrations, as well as the mRNA expression of mTOR signaling-associated genes TSC1, TSC2, mTOR, 4E-BP1, and S6K in old later-period chicken control (Old-CN) group was significantly decreased (P < 0.01). In contrast, the ERS-related of plasma and granular cell layer mRNA expression of Grp78, CHOP, and Caspase-3 was significantly increased (P < 0.01). While both of the effects were reversed by MEL. Then, aging granulosa cells were treated with MEL in vitro, followed by RNA seq analysis, and it was found that 259 and 322 genes were upregulated and downregulated. After performing GO enrichment analysis, it was found that DEGs significantly contribute to the biological processes including cell growth and apoptosis. Using pathway enrichment analysis, we found significant overrepresentation of cellular processes related to mTOR signaling and endoplasmic reticulum (ER) stress, involving genes such as GRB10, SGK1, PRKCA, RPS6KA2, RAF1, PIK3R3, FOXO1, DERL3, HMOX1, TLR7, VAMP7 and INSIG2. The obtained results of RT-PCR showed consistency with the RNA-Seq data. In summary, the underlined results revealed that MEL has significantly contributed to follicular development via activating the mTOR signaling pathway-related genes and alleviating ERS-related genes in laying hens. The current study provides a theoretical background for enhancing the egg-laying capability of hens and also providing a basis for elucidating the molecular mechanism of follicular selection.

Carboplatin restricts peste des petits ruminants virus replication by suppressing the STING-mediated autophagy

Peste des petits ruminants virus (PPRV) is a morbillivirus that causes the acute and highly pathogenic infectious disease peste des petits ruminants (PPR) in small ruminants and poses a major threat to the goat and sheep industries. Currently, there is no effective treatment for PPRV infection. Here, we propose Carboplatin, a platinum-based regimen designed to treat a range of malignancies, as a potential antiviral agent. We showed that Carboplatin exhibits significant antiviral activity against PPRV in a cell culture model. The mechanism of action of Carboplatin against PPRV is mainly attributed to its ability to block STING mediated autophagy. Together, our study supports the discovery of Carboplatin as an antiviral against PPRV and potentially other closely related viruses, sheds light on its mode of action, and establishes STING as a valid and attractive target to counteract viral infection.

Exploring melatonin's multifaceted role in female reproductive health: From follicular development to lactation and its therapeutic potential in obstetric syndromes

BACKGROUND

Melatonin is mainly secreted by the pineal gland during darkness and regulates biological rhythms through its receptors in the suprachiasmatic nucleus of the hypothalamus. In addition, it also plays a role in the reproductive system by affecting the function of the hypothalamic-pituitary-gonadal axis, and by acting as a free radical scavenger thus contributing to the maintenance of the optimal physiological state of the gonads. Besides, melatonin can freely cross the placenta to influence fetal development. However, there is still a lack of overall understanding of the role of melatonin in the reproductive cycle of female mammals.

AIM OF REVIEW

Here we focus the role of melatonin in female reproduction from follicular development to delivery as well as the relationship between melatonin and lactation. We further summarize the potential role of melatonin in the treatment of preeclampsia, polycystic ovary syndrome, endometriosis, and ovarian aging.

KEY SCIENTIFIC CONCEPTS OF REVIEW

Understanding the physiological role of melatonin in female reproductive processes will contribute to the advancement of human fertility and reproductive medicine research.

New insights into the treatment of polycystic ovary syndrome: HKDC1 promotes the growth of ovarian granulocyte cells by regulating mitochondrial function and glycolysis

Polycystic ovary syndrome (PCOS) is an endocrine disease, and its pathogenesis and treatment are still unclear. Hexokinase domain component 1 (HKDC1) participates in regulating mitochondrial function and glycolysis. However, its role in PCOS development remains unrevealed. Here, female C57BL/6 mice were intraperitoneally injected with dehydroepiandrosterone (DHEA; 60 mg/kg body weight) to establish an in vivo model of PCOS. In vitro, KGN cells, a human ovarian granular cell line, were used to explore the potential mechanisms. DHEA-treated mice exhibited a disrupted estrus cycle, abnormal hormone levels, and insulin resistance. Dysfunction in mitochondria and glycolysis is the main reason for PCOS-related growth inhibition of ovarian granular cells. Here, we found that the structure of mitochondria was impaired, less ATP was generated and more mitochondrial Reactive Oxygen Species were produced in HKDC1-silenced KGN cells. Moreover, HKDC1 knockdown inhibited glucose consumption and decreased the production of glucose-6-phosphate and lactic acid. Conclusively, HKDC1 protects ovarian granulocyte cells from DHEA-related damage at least partly by preserving mitochondrial function and maintaining glycolysis.

Melatonin regulates autophagy in granulosa cells from patients with premature ovarian insufficiency via activating Foxo3a

Premature ovarian insufficiency (POI) is a diverse form of female infertility characterized by a decline in ovarian function before the age of 40. Melatonin (MT) is a potential clinical treatment for restoring or safeguarding ovarian function in POI. However, the specific therapeutic mechanism underlying this effect remains unclear. To address this, we conducted experiments using human granulosa cells (GCs) from both POI and normal patients. We examined the expression levels of autophagy-related genes and proteins in GCs through qRT-PCR and western blot analysis. Autophagy flux was monitored in GCs infected with GFP-LC3-adenovirus, and the regulatory function of MT in autophagy was investigated. Additionally, we employed pharmacological intervention of autophagy using 3-Methyladenine (3-MA) and RNA interference of Forkhead box O-3A (FOXO3A) to elucidate the mechanism of MT in the autophagy process. Compared to GCs from normal patients, GCs from POI patients exhibited irregular morphology, decreased proliferation, increased apoptosis, and elevated ROS levels. The expression of autophagy-related genes was downregulated in POI GCs, resulting in reduced autophagic activity. Furthermore, MT levels were decreased in POI GCs, but exogenous MT effectively activated autophagy. Mechanistically, melatonin treatment downregulated FOXO3A expression and induced phosphorylation in POI GCs. Importantly, silencing FOXO3A abolished the protective effect of melatonin on GCs. These findings indicate that autophagy is downregulated in POI GCs, accompanied by a deficiency in MT. Moreover, we demonstrated that supplementing MT can rescue autophagy levels and enhance GC viability through the activation of FOXO3A signaling. Thus, MT-FOXO3A may serve as a potential therapeutic target for POI treatment.

Selenium Protects Follicular Granulosa Cells from Apoptosis Induced by Mercury Through Inhibition of ATF6/CHOP Pathway in Laying Hens

The purpose of this research was to explore the effect of selenium on mercury-mediated apoptosis of follicular granulosa cells in laying hens. Moreover, the ATF6/CHOP pathway was investigated to explore the mechanism in this progress. Hg, Se, and 4-phenyl butyric acid were used alone or in combination to treat the cells. Our results showed that the nuclear in cells became condensate after Hg exposure, while Se addition significantly alleviated this change. Hg exposure significantly induced the apoptosis and the reduction of mitochondrial membrane potential in cells (P < 0.05). Nevertheless, co-treatment of Se significantly inhibited these effects (P < 0.05). Additionally, Hg exposure dramatically elevated the gene expressions of Bax/Bcl-2 (P < 0.05), caspase-3 (P < 0.05), caspase-9 (P < 0.05), protein kinase RNA-like endoplasmic reticulum kinase (P < 0.05), activating transcription factor 6 (P < 0.05), C/EBP homologous protein (CHOP; P < 0.05), inositol-requiring enzyme 1α (P < 0.05), tumor necrosis factor-associated factor 2 (P < 0.05), activating transcription factor 6 (ATF6; P < 0.05), and apoptosis signal-regulating kinase 1 (P < 0.05) in cells, whereas Se addition avoided these changes. The exposure to Hg considerably boosted the expression of ATF6 and CHOP protein (P < 0.05), while Se addition significantly alleviated the above-mentioned enhancements (P < 0.05). In summary, Hg exposure induced apoptosis, which was considerably reduced alleviated by Se addition, which was linked to the ATF6/CHOP pathway in follicular granulosa cells in laying hens.

Current Advances in Cellular Approaches for Pathophysiology and Treatment of Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) is a prevalent gynecological and endocrine disorder that results in irregular menstruation, incomplete follicular development, disrupted ovulation, and reduced fertility rates among affected women of reproductive age. While these symptoms can be managed through appropriate medication and lifestyle interventions, both etiology and treatment options remain limited. Here we provide a comprehensive overview of the latest advancements in cellular approaches utilized for investigating the pathophysiology of PCOS through in vitro cell models, to avoid the confounding systemic effects such as in vitro fertilization (IVF) therapy. The primary objective is to enhance the understanding of abnormalities in PCOS-associated folliculogenesis, particularly focusing on the aberrant roles of granulosa cells and other relevant cell types. Furthermore, this article encompasses analyses of the mechanisms and signaling pathways, microRNA expression and target genes altered in PCOS, and explores the pharmacological approaches considered as potential treatments. By summarizing the aforementioned key findings, this article not only allows us to appreciate the value of using in vitro cell models, but also provides guidance for selecting suitable research models to facilitate the identification of potential treatments and understand the pathophysiology of PCOS at the cellular level.

Melatonin Protects the Apoptosis of Sheep Granulosa Cells by Suppressing Oxidative Stress via MAP3K8 and FOS Pathway

Melatonin is not only a highly effective active oxygen scavenger but also an important reproductive hormone. Melatonin has a regulatory effect on animal reproduction, especially on the ovaries. It can affect the proliferation and apoptosis of cells in follicles. However, the mechanisms of the dual antioxidation and anti-apoptosis effects of melatonin on granulosa cells are still not clear, especially in sheep. Therefore, we investigated the mechanisms of the protective effect of melatonin against oxidative damage in granulosa cells. At a concentration of 250 µmol/L, H₂O₂ promoted granulosa cell apoptosis; however, 10 ng/mL melatonin effectively alleviated the pro-apoptotic effect of H₂O₂. Furthermore, through the application of high-throughput sequencing technology, we identified 109 significantly differentially expressed genes (35 upregulated and 74 downregulated genes) involved in the protective effect of melatonin against apoptosis. The expression levels of nine related genes, i.e., ATF3, FIBIN, FOS, HSPA6, MAP3K8, FOSB, PET117, DLX2, and TRIB1, changed significantly. MAP3K8 and FOS gene overexpression impacted the protective effect of melatonin in granulosa cells; the two genes exhibited an upstream and downstream regulatory relationship. Our findings indicated that melatonin alleviated H₂O₂-induced apoptosis in sheep granulosa cells through the MAP3K8-FOS pathway.

PPT1 regulation of HSP90α depalmitoylation participates in the pathogenesis of hyperandrogenism

Ovarian granulosa cells (GCs) in the follicle are the important mediator of steroidogenesis and foster oocyte maturation. Evidences suggested that the function of GCs could be regulated by S-palmitoylation. However, the role of S-palmitoylation of GCs in ovarian hyperandrogenism remains elusive. Here, we demonstrated that the protein from GCs in ovarian hyperandrogenism phenotype mouse group exhibits lower palmitoylation level compared with that in the control group. Using S-palmitoylation-enriched quantitative proteomics, we identified heat shock protein isoform α (HSP90α) with lower S-palmitoylation levels in ovarian hyperandrogenism phenotype group. Mechanistically, S-palmitoylation of HSP90α modulates the conversion of androgen to estrogens via the androgen receptor (AR) signalling pathway, and its level is regulated by PPT1. Targeting AR signaling by using dipyridamole attenuated ovarian hyperandrogenism symptoms. Our data help elucidate ovarian hyperandrogenism from perspective of protein modification and provide new evidence showing that HSP90α S-palmitoylation modification might be a potential pharmacological target for ovarian hyperandrogenism treatment.

Molecular mechanism of Wilms' tumor (Wt1) (+/-KTS) variants promoting proliferation and migration of ovarian epithelial cells by bioinformatics analysis

Epithelial ovarian cancer (EOC) is a gynecological disease with the highest mortality. With the lack of understanding of its pathogenesis, no accurate early diagnosis and screening method has been established for EOC. Studies revealed the multi-faceted function of Wilms' tumor (Wt1) genes in cancer, which may be related to the existence of multiple alternative splices. Our results show that Wt1 (+KTS) or Wt1 (-KTS) overexpression can significantly promote the proliferation and migration of human ovarian epithelial cells HOSEpiC, and Wt1 (+KTS) effects were more evident. To explore the Wt1 (+/-KTS) variant mechanism in HOSEpiC proliferation and migration and ovarian cancer (OC) occurrence and development, this study explored the differential regulation of Wt1 (+/-KTS) in HOSEpiC proliferation and migration by transcriptome sequencing. OC-related hub genes were screened by bioinformatics analysis to further explore the differential molecular mechanism of Wt1 (+/-KTS) in the occurrence of OC. Finally, we found that the regulation of Wt1 (+/-KTS) variants on the proliferation and migration of HOSEpiC may act through different genes and signaling pathways and screened out key genes and differentially regulated genes that regulate the malignant transformation of ovarian epithelial cells. The implementation of this study will provide new clues for the early diagnosis and precise treatment of OC.

High-Fat Diet and Female Fertility across Lifespan: A Comparative Lesson from Mammal Models

Female reproduction focuses mainly on achieving fully grown follicles and competent oocytes to be successfully fertilized, as well as on nourishing the developing offspring once pregnancy occurs. Current evidence demonstrates that obesity and/or high-fat diet regimes can perturbate these processes, leading to female infertility and transgenerational disorders. Since the mechanisms and reproductive processes involved are not yet fully clarified, the present review is designed as a systematic and comparative survey of the available literature. The available data demonstrate the adverse influences of obesity on diverse reproductive processes, such as folliculogenesis, oogenesis, and embryo development/implant. The negative reproductive impact may be attributed to a direct action on reproductive somatic and germinal compartments and/or to an indirect influence mediated by the endocrine, metabolic, and immune axis control systems. Overall, the present review highlights the fragmentation of the current information limiting the comprehension of the reproductive impact of a high-fat diet. Based on the incidence and prevalence of obesity in the Western countries, this topic becomes a research challenge to increase self-awareness of dietary reproductive risk to propose solid and rigorous preventive dietary regimes, as well as to develop targeted pharmacological interventions.

Protective effect of nano-selenium on mercury-induced prehierarchical follicular atresia in laying hens

This study investigated the effect of nano-selenium (nano-Se) in protecting laying hens from mercury (Hg)-induced prehierarchical follicular atresia. Furthermore, the endoplasmic reticulum stress (ERS) was explored to reveal the molecular mechanism. In vivo, 720 Hyline-Brown laying hens were treated with Hg and nano-Se alone or in combination. In vitro, the prehierarchical follicles were treated with Hg, nano-Se and 4-phenyl butyric acid (4-PBA) alone or in combination (Control, 25 μM Hg group, 10 μM nano-Se group, 20 μM nano-Se group, 25 μM Hg + 10 μM nano-Se group, 25 μM Hg + 20 μM nano-Se group, 25 μM Hg + 4-PBA group, and 25 μM Hg + 20 μM nano-Se + 4-PBA group). The GCs were treated with Hg and nano-Se alone or in combination (Control, 15 μM Hg group, 6 μM nano-Se group, 12 μM nano-Se group, 15 μM Hg + 6 μM nano-Se group, 15 μM Hg + 12 μM nano-Se group). The results revealed that dietary Hg significantly reduced laying performance (P < 0.05) and egg quality (P < 0.05), whereas nano-Se addition prevented these reductions (P < 0.05). Hg exposure significantly induced the accumulation of Hg in PHFs (P < 0.05), prehierarchical follicular atresia (P < 0.05) and apoptosis in PHFs, whereas nano-Se addition significantly prevented these effects (P < 0.05). The levels of sex hormones (P < 0.05) were significantly decreased after Hg exposure in vivo and in vitro, while nano-Se addition prevented the reductions. Furthermore, the RNA-Seq results showed that the key factors of the ERS presented differential expression, including C/EBP homologous protein, protein kinase RNA-like endoplasmic reticulum kinase (PERK) and activating transcription factor 6 (ATF6) in GCs. Hg exposure significantly increased the key gene expression of endoplasmic reticulum stress in GCs, whereas nano-Se addition prevented the induction of expression of these genes. In addition, the protein levels of PERK, inositol requiring protein 1α (IRE1α) and ATF6 were significantly increased, whereas nano-Se addition prevented the enhancements of protein expression in GCs. In conclusion, this study shows that Hg exposure can reduce induce prehierarchical follicular atresia, whereas nano-Se can prevent these effects. Our results also elucidate a key role of ERS in these protective effects of nano-Se in laying hens.

Melatonin attenuates LPS-induced ovarian toxicity via modulation of SIRT-1, PI3K/pAkt, pErk1/2 and NFĸB/COX-2 expressions

The association between inflammation and metabolic disturbances leads to various female pathophysiological conditions. Bacterial lipopolysaccharide (LPS), found in the outer membrane of gram-negative bacteria, elicits an oxidative and inflammatory response that profoundly interferes with female reproductive health. We investigated the ameliorative action of melatonin on LPS-induced ovarian pathophysiology in golden hamsters, Mesocricetus auratus. Hamsters were administered with exogenous melatonin (5 mg/kg BW) and LPS (100 μg/kg BW) intraperitoneally for 7 days. LPS treatment impaired ovarian folliculogenesis as evident by histoarchitecture (elevated number of atretic follicles, reduced number of growing follicles and corpus luteum) and steroidogenesis (decreased aromatase/ERα, estradiol and progesterone). On the other hand, LPS administration also perturbed thyroid hormone (T3 and T4) homeostasis, ovarian melatonin receptor (MT-1) expression, antioxidant potential (SOD and catalase) and concomitantly elevated nitro-oxidative stress (decreased SOD, catalase and elevated CRP, TNFα and nitrate/nitrite level) and inflammatory load (NFĸB and COX-2) which culminated into ovarian follicular apoptosis (elevated caspase-3). LPS also disrupted metabolic homeostasis as indicated by hyperinsulinemia with a simultaneous decrease in ovarian IR/GLUT-4 and glucose content. Moreover, LPS treatment decreased expressions of key markers of ovarian physiology (SIRT-1, pErk1/2, PI3K and pAkt). Melatonin co-treatment with LPS improve these detrimental changes proposing melatonin as a potent therapeutic candidate against ovarian dysfunction induced by endotoxin.

Peste des petits ruminants virus induces ERS-mediated autophagy to promote virus replication

Peste des petits ruminants virus (PPRV) has long been a significant threat to small ruminant productivity worldwide. Virus infection-induced endoplasmic reticulum (ER) stress (ERS) and the subsequently activated unfolded protein response (UPR) play significant roles in viral replication and pathogenesis. However, the relationship between ERS and PPRV infection is unknown. In this study, we demonstrated that ERS was induced during PPRV infection in caprine endometrial epithelial cells (EECs). Importantly, we demonstrated that the induction of autophagy by PPRV was mediated by ERS. Furthermore, we found that the PERK/eIF2α pathway but not the ATF6 or IRE1 pathway was activated and that the activated PERK/eIF2α pathway participated in regulating ERS-mediated autophagy. Moreover, virus replication was required for PPRV infection-induced ERS-mediated autophagy and PERK pathway activation. Additionally, we revealed that either the viral nucleocapsid (N) or nonstructural protein C was sufficient to elicit ERS and activate the PERK/eIF2α pathway, which further increased autophagy. Taken together, these results suggest that PPRV N and C protein-induced autophagy enhances viral replication through the induction of ERS and that the PERK pathway may be involved in the activation of ERS-mediated autophagy during PPRV infection.

Oxidative Stress-Induced Growth Inhibitor (OSGIN1), a Target of X-Box-Binding Protein 1, Protects Palmitic Acid-Induced Vascular Lipotoxicity through Maintaining Autophagy

Saturated free fatty acids (FFAs) strongly correlate with metabolic syndromes and are well-known risk factors for cardiovascular diseases (CVDs). The mechanism of palmitic acid (PA)-induced vascular lipotoxicity under endoplasmic reticulum (ER) stress is unknown. In the present paper, we investigate the roles of spliced form of X-box-binding protein 1 (XBP1s) target gene oxidative stress-induced growth inhibitor 1 (OSGIN1) in PA-induced vascular dysfunction. PA inhibited the tube formation assay of primary human umbilical vein endothelial cells (HUVECs). Simultaneously, PA treatment induced the XBP1s expression in HUVECs. Attenuate the induction of XBP1s by silencing the XBP1s retarded cell migration and diminished endothelial nitric oxide synthase (eNOS) expression. OSGIN1 is a target gene of XBP1s under PA treatment. The silencing of OSGIN1 inhibits cell migration by decreasing phospho-eNOS expression. PA activated autophagy in endothelial cells, inhibiting autophagy by 3-methyladenine (3-MA) decreased endothelial cell migration. Silencing XBP1s and OSGIN1 would reduce the induction of LC3 II; therefore, OSGIN1 could maintain autophagy to preserve endothelial cell migration. In conclusion, PA treatment induced ER stress and activated the inositol-requiring enzyme 1 alpha–spliced XBP1 (IRE1α–XBP1s) pathway. OSGIN1, a target gene of XBP1s, could protect endothelial cells from vascular lipotoxicity by regulating autophagy.

Quercetin Alleviates Endoplasmic Reticulum Stress-Induced Apoptosis in Buffalo Ovarian Granulosa Cells

Simple Summary

Granulosa cells are critical components of the ovary that nurture germ cells and sustain oocyte maturation. Apoptosis of granulosa cells leads to follicular atresia, which in turn leads to female infertility. There are many reasons for the apoptosis of granulosa cells, one of which is apoptosis induced by endoplasmic reticulum stress. We found that quercetin could attenuate the effects of endoplasmic reticulum stress on granulosa cells by the PERK/CHOP signaling pathway. The results provide a novel strategy for inhibiting the apoptosis of granulosa cells.

Abstract

Endoplasmic reticulum (ER) stress plays a crucial role in granulosa cell (GCs) apoptosis, which is the main cause of follicular atresia. Quercetin (QC), a plant-derived flavonoid, has antioxidant, anti-inflammatory, and other biological properties. However, whether QC can alleviate the effects of ER stress on buffalo GCs remains unknown. In this study, we constructed an ER stress model in buffalo GCs by using tunicamycin (TM) and pre-treated with QC to explore the effect of QC on cells under ER stress. Apoptosis was detected by Annexin fluorescein 5 isothiocyanate (V-FITC), and the expressions of mRNA and related proteins involved in ER stress and apoptosis were detected via real-time polymerase chain reaction and Western blot. The results revealed that ER stress can cause apoptosis in GCs, whereas QC pre-treatment can prevent apoptosis caused by ER stress. After pre-treatment with QC, the expression levels of ER stress-related genes and proteins significantly decreased, pro-apoptotic genes were significantly down-regulated, and anti-apoptotic genes were significantly up-regulated. Furthermore, the results of Chop gene overexpression suggested that QC alleviated ER stress via the PERK/CHOP signaling pathway. In this study, we preliminarily elucidated that QC alleviates ER stress-induced apoptosis in buffalo GCs, and the results suggest a novel strategy for delaying follicular atresia by inhibiting GCs apoptosis.

Stress associated ovarian dysfunctions in a seasonal breeder Funambulus pennanti: Role of glucocorticoids and possible amelioration by melatonin

Studies have shown that stress caused by lack of physical activity disrupts the normal pattern of glucocorticoid secretion which adversely affects the reproductive axis. We studied the effect of chronic movement restriction on ovarian responses in the Indian Palm Squirrel Funambulus pennanti, a highly active diurnal rodent. Physical restraint of squirrels induced stress that led to a significant increase in plasma cortisol, corticosterone and decreased 17β-estradiol level leading to follicular atresia. Ovarian Reactive Oxygen Species (ROS) content, lipid peroxidation (LPO), activities of superoxide dismutase (SOD) and catalase (CAT) enzymes increased in restrained squirrels. Elevated ROS increased the oxidative load that led to ovarian cell death as evidenced by increased Bax and decreased Bcl2 expression causing further decline in Aromatase and ERα proteins. To elaborate the mechanism(s) involved in stress induced glucocorticoid mediated oxidative damages to the ovary we extended our study by exposing ovaries in vitro to the synthetic glucocorticoid dexamethasone (200 μM). We observed that glucocorticoid receptor (GR) expression was significantly increased in dexamethasone treated ovaries in vitro with a decrease in expression of Nrf2 and HO-1 proteins. Melatonin supplementation (10 nM) along with dexamethasone significantly decreased ovarian ROS production, lipid peroxidation and increased antioxidant enzyme activities by improving the expression of Nrf2 and HO-1, reinstating the cellular redox homeostasis. Therefore, it can be suggested that physical restraint induced glucocorticoid and its receptor activation interfered with the ovarian antioxidant defense mechanism. Melatonin via its receptor MT1 significantly alleviated ovarian damages acting as a cytoprotective agent.

Melatonin alleviates insulin resistance through the PI3K/AKT signaling pathway in ovary granulosa cells of polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is a common endocrine gynecological disorder. Insulin resistance (IR) is a major cause of PCOS. Melatonin, a critical endogenous hormone, has beneficial effects on the female reproductive system. This study aims to investigate the molecular effect of melatonin on IR in human ovarian granulosa cells (GCs). Hormone levels of the subjects were determined through clinical examination. The expression levels of insulin receptor substrate (IRS)-1 and glucose transporter (GLUT4) in GCs from PCOS patients and a human granulosa cell line (SVOG) were examined using qRT-PCR and western blot. The IR cell model was established by inducing SVOG cells with palmitic acid (PA). IR was detected in GCs of PCOS patients and SVOG by measuring glucose content and glucose uptake. Cell viability and apoptosis levels were detected by CCK-8 assay and flow cytometry. PI3K/Akt pathway expression in SVOG was assessed by western blot. PCOS patients had higher levels of luteinizing hormone (LH), testosterone, and LH/follicle-stimulating hormone. PA decreased cell viability, promoted apoptosis, and reduced glucose uptake in SVOG cells. IRS-1 and GLUT4 mRNA and protein expression was downregulated, and glucose uptake capacity was reduced in PCOS GCs and SVOG cells. Melatonin significantly upregulated IRS-1 and GLUT4 expression, downregulated p-IRS-1 (Ser307), and improved glucose uptake in PCOS patients' GCs and SVOG cells. PA decreased PI3K and Akt phosphorylation, whereas melatonin increased p-PI3K and p-Akt levels. Melatonin can reduce IR in GCs and PA-induced SVOG cells via the PI3K/Akt signaling pathway, providing more evidence for treating polycystic ovary syndrome.

The Effect of Melatonin on OCT4 Expression and Granulosa Cell Growth in Female Mice

Melatonin is mainly secreted by the pineal gland as a neurotransmitter. Moreover, melatonin is also produced by the ovary and plays important roles in female reproduction. However, it is unclear whether melatonin has any effect on the transition from the preantral follicle to the early antral follicle. Octamer-binding transcription factor 4 (OCT4) is important to granulosa cells development, which is regulated by gonadotropin. And these regulations are mediated by the GSK3β/β-catenin pathway via the activated PI3K/Akt signaling. The aim of the present study was to determine the effects and the possible mechanisms of melatonin on ovarian cells development. The results showed that melatonin inhibited granulosa cells development, which was accompanied by the downregulation of OCT4 expression. Meanwhile, melatonin also decreased the expression of p-GSK3β (glycogen synthase kinase 3 beta), p-Akt, β-catenin, and its translocation to the nucleus in granulosa cells. Moreover, melatonin attenuated the effects of FSH in vitro and eCG in vivo on these regulations. In conclusion, this study shows that melatonin inhibits ovarian cell development by downregulating the OCT4 expression level, which is possibly mediated by inhibiting the PI3K/Akt and GSK3β/β-catenin pathway. Melatonin attenuates the effects of gonadotropin on ovarian granulosa cells as a negative regulator.

Cocultured porcine granulosa cells respond to excess non-esterified fatty acids during in vitro maturation

Background

Non-esterified fatty acids (NEFAs) are one of the main lipid components of follicular fluid at concentrations that depend on circulating levels. Elevated levels of NEFAs impair oocyte quality, development potential, and may subsequently influence the metabolism and reproductive fitness of offspring. Granulosa cells (GCs) are the follicular cells that are closely communicating with the oocyte. However, the responses of GCs exposed to high levels of NEFAs when cocultured with cumulus-oocyte complexes (COCs), and how they attenuate the negative effects of NEFAs on oocytes, are unclear.

Results

To better understand this protective effect, monolayers of porcine GCs were cocultured with COCs during in vitro maturation (IVM) in the presence of elevated levels of NEFAs. Genomic expression analysis was conducted to explore the responses of the GCs to the elevated levels of NEFAs. After limma algorithm analysis, 1,013 genes were differentially expressed between GCs cultured with and without elevated NEFAs. Among them, 438 genes were upregulated and 575 were downregulated. The differentially expressed genes were enriched in pathways related to metabolism, inflammation, and epithelial-mesenchymal transition.

Conclusions

The pathways and upstream regulators suggested that the cocultured GCs responded to the elevated NEFAs with (1) inhibition of the transition from granulosa to luteal cell, (2) interactions of metabolism change, anti-inflammation, mitochondrial function, and cell transition, (3) intercommunication with cocultured COCs of anti-inflammatory factors.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13048-021-00904-y.

5-Aminolevulinic Acid Attenuates Glucose-Regulated Protein 78 Expression and Hepatocyte Lipoapoptosis via Heme Oxygenase-1 Induction

Endoplasmic reticulum (ER) stress plays a pivotal role in the progression of steatohepatitis. 5-aminolevulinic acid (5-ALA), a precursor in the heme biosynthetic pathway, has recently been reported to induce heme oxygenase (HO)-1. HO-1 exerts important cytoprotective actions. In this study, we aimed to explore the therapeutic potential of 5-ALA on palmitate-induced ER stress and lipoapoptosis. Huh-7 cells were treated with palmitic acid (PA) (800 μM) to induce steatosis for eight hours. Steatosis was evaluated by Lipi-green staining. 5-ALA (200 μM) was added with PA. The gene expression levels of the nuclear factor erythroid 2-related factor 2 (NRF2), HO-1, Glucose-regulated protein 78 (GRP78), activating transcription factor 6 (ATF6), PKR-like endoplasmic reticulum kinase (PERK), inositol-requiring enzyme 1 (IRE1), C/EBP homologous protein (CHOP), and B-cell lymphoma 2 (BCL-2) were evaluated by RT-PCR. Caspase-3/7 activity was evaluated by fluorescein active Caspase-3/7 staining. Cell death was evaluated by Annexin V/SYTOX green staining. PA significantly induced steatosis and increased GRP78 expression in Huh-7 cells. 5-ALA significantly induced HO-1 and decreased GRP78 expression. ATF6 was subsequently decreased. However, NRF2 and CHOP expression were not altered. Anti-apoptotic BCL-2 expression significantly increased, and Caspase 3/7 activity and cell death also decreased. 5-ALA has a therapeutic potential on hepatic steatosis by suppressing ER stress and lipoapoptosis by attenuating GRP78 via HO-1 induction.

Integration of transcriptomics and non-targeted metabolomics reveals the underlying mechanism of follicular atresia in Chinese buffalo

Follicular atresia is a complex physiological process, which results in the waste of follicles and oocytes from the ovary. Elucidating the physiological mechanism of follicular atresia will hopefully reverse the fate of follicles, thereby improve the reproductive efficiency of female animals. However, there are still many gaps to be filled during the follicular atresia process. In this study, we first comprehensively summarized and compared a variety of methods to classify Chinese buffalo follicles with different extent of atresia. Then follicular fluid and granulosa cells from the corresponding follicles with different extent of atresia were collected for non-targeted metabolomics and transcriptomics analysis, respectively. After the detection and analysis of 129 follicles, a reasonable classification standard was formed: on the basis of morphological classification, the relative concentrations of estradiol (E2) and progesterone (PROG) in the follicular fluid were determined, follicles with an estradiol-to-progesterone (E2/PROG) ratio >5 were classified as healthy follicles (HF), 1≤ E2/PROG ≤5 as early atretic follicles (EF) and E2/PROG <1 as late atretic follicles (LF). Correspondingly, follicles with granulosa cells apoptosis rate less than 15 % were divided into HF, 15%-25% were classified as EF and more than 25 % were classified as LF. The integration analysis of non-targeted metabolomics and transcriptomics highlights the following three aspects: (1) Atresia seriously damaged the lipid metabolism homeostasis of follicle, in which PPARγ play important roles. (2) Energy metabolism and nucleotide metabolism of atretic follicles were inhibited. (3) Bilirubin is involved in follicular atresia, and it may be the main force to prevent lipid peroxidation in follicular cells. In summary, results of this study provide new understanding of the molecular mechanisms of Chinese buffalo follicular atresia.

Melatonin Represses Mitophagy to Protect Mouse Granulosa Cells from Oxidative Damage

Various environmental stimuli, including oxidative stress, could lead to granulosa cell (GC) death through mitophagy. Recently, it was reported that melatonin (MEL) has a significant effect on GC survival during oxidative damage. Here, we found that MEL inhibited oxidative stress-induced mitophagy to promote GC survival. The loss of cell viability upon H₂O₂ exposure was significantly restored after MEL treatment. Concomitantly, MEL inhibited the activation of mitophagy during oxidative stress. Notably, blocking mitophagy repressed GC death caused by oxidative stress. However, MEL cannot further restore viability of cells treated with mitophagy inhibitor. Moreover, PTEN-induced putative kinase 1 (PINK1), a mitochondrial serine/threonine-protein kinase, was inhibited by MEL during oxidative stress. As a result, the E3 ligase Parkin failed to translocate to mitochondria, leading to impaired mitochondria clearance. Using RNAi to knock down PINK1 expression, we further verified the role of the MEL-PINK1-Parkin (MPP) pathway in maintaining GC survival by suppressing mitophagy. Our findings not only clarify the protective mechanisms of MEL against oxidative damage in GCs, but also extend the understanding about how circadian rhythms might influence follicles development in the ovary. These findings reveal a new mechanism of melatonin in defense against oxidative damage to GCs by repressing mitophagy, which may be a potential therapeutic target for anovulatory disorders.

N-acetyl-L-cysteine Improves the Developmental Competence of Bovine Oocytes and Embryos Cultured In Vitro by Attenuating Oxidative Damage and Apoptosis

Oxidative stress has been suggested to negatively affect oocyte and embryo quality and developmental competence, resulting in failure to reach full term. In this study, we investigated the effect of N-acetyl-L-cysteine (NAC), a cell-permeating antioxidant, on developmental competence and the quality of oocytes and embryos upon supplementation (0.1–10 mM) in maturation and culture medium in vitro using slaughterhouse-derived oocytes and embryos. The results show that treating oocytes with 1.0 mM NAC for 8 h during in vitro maturation attenuated the intracellular reactive oxygen species (ROS) (p < 0.05) and upregulated intracellular glutathione levels (p < 0.01) in oocytes. Interestingly, we found that NAC affects early embryonic development, not only in a dose-dependent, but also in a stage-specific, manner. Significantly (p < 0.05) decreased cleavage rates (90.25% vs. 81.46%) were observed during the early stage (days 0–2), while significantly (p < 0.05) increased developmental rates (38.20% vs. 44.46%) were observed during the later stage (from day 3) of embryonic development. In particular, NAC supplementation decreased the proportion of apoptotic blastomeres significantly (p < 0.05), resulting in enhanced hatching capability and developmental rates during the in vitro culture of embryos. Taken together, our results suggest that NAC supplementation has beneficial effects on bovine oocytes and embryos through the prevention of apoptosis and the elimination of oxygen free radicals during maturation and culture in vitro.

Melatonin alleviates deoxynivalenol-induced apoptosis of human granulosa cells by reducing mutually accentuated FOXO1 and ER stress‡

Deoxynivalenol (DON) is one of the most prevalent Fusarium mycotoxins, which cause detrimental effects on human and animal reproductive systems by inducing oxidative stress. Increasing evidence has suggested the potential roles of melatonin in protecting granulosa cells from oxidative injury, but the underlying mechanisms remain largely elusive. Here, we demonstrated that suppression of FOXO1 and endoplasmic reticulum (ER) stress was engaged in melatonin-mediated protection against oxidative damage in human granulosa cells upon DON exposure in vitro. DON induced excess reactive oxygen species accumulation, cells viability loss, reduced estradiol-17β, and progesterone production in human granulosa cells, whereas melatonin ameliorated these phenotypes. Next, we found that the protective effect of melatonin against apoptosis was via reducing ER stress because the inhibition of ER stress displayed similar protective effects during DON treatment. Moreover, melatonin provided no additional protection when ER stress was inhibited. We further found that FOXO1 is a pivotal downstream effector of melatonin and ER stress in regulating DON-induced apoptosis in human granulosa cells. Blocking of FOXO1 reduced DON-induced cells death and FOXO1 activation could be suppressed by melatonin or ER stress inhibitor. However, melatonin failed to further restore cells viability in the presence of FOXO1 inhibitor. Collectively, our results reveal a new mechanism of melatonin in protecting against DON-induced apoptosis and dysfunction by suppressing ER stress and FOXO1 in human granulosa cells.

ER stress modulates apoptosis in A431 cell subjected to EtNBSe-PDT via the PERK pathway

Photodynamic therapy (PDT) is a promising modality against various cancers including squamous cell carcinoma (SCC) with which the induction of apoptosis is an effective mechanism. Here, we initially describe the preclinical activity of 5-ethylamino-9-diethylaminobenzo [a] phenoselenazinium(EtNBSe)-mediated PDT treatment in SCC. Results of our studies suggest that EtNBSe-PDT provokes a cellular state of endoplasmic reticulum (ER) stress triggering the PERK/ eIF2α signaling pathway and induces the appearance of apoptosis in A431 cells at the meantime. With ER stress inhibitor 4-PBA or eIF2α inhibitor ISRIB, suppressing the EtNBSe-PDT induced ER stress substantially promotes apoptosis of A431 cells. Furthermore, we demonstrate that ATF4, whose expression is ER-stress-inducible and elevated in response to the PERK/eIF2α signaling pathway activation, contributes to cytoprotection against EtNBSe-PDT induced apoptosis. In a mouse model bearing A431 cells, EtNBSe shows intense phototoxicity and when associated with decreased ER stress, EtNBSe-PDT ameliorates tumor growth. Taken together, our study reveals an antagonistic activity of ER stress against EtNBSe-PDT treatment via inhibiting apoptosis in A431 cells. With further development, these results provide a proof-of-concept that downregulation of ER stress response has a therapeutic potential to improve EtNBSe-PDT sensitivity in SCC patients via the promotion of induced apoptosis.

5-ALA Attenuates the Palmitic Acid-Induced ER Stress and Apoptosis in Bovine Mammary Epithelial Cells

The conservation of mammary gland physiology by maintaining the maximum number of mammary epithelial cells (MECs) is of the utmost importance for the optimum amount of milk production. In a state of negative energy balance, palmitic acid (PA) reduces the number of bovine MECs. However, there is no effective strategy against PA-induced apoptosis of MECs. In the present study, 5-aminolevulinic acid (5-ALA) was established as a remedial agent against PA-induced apoptosis of MAC-T cells (an established line of bovine MECs). In PA-treated cells, the apoptosis-related genes BCL2 and BAX were down- and upregulated, respectively. The elevated expression of major genes of the unfolded protein response (UPR), such as CHOP, a proapoptotic marker (C/EBP homologous protein), reduced the viability of PA-treated MAC-T cells. In contrast, 5-ALA pretreatment increased and decreased BCL2 and BAX expression, respectively. Moreover, cleaved caspase-3 protein expression was significantly reduced in the 5-ALA-pretreated group in comparison with the PA group. The downregulation of major UPR-related genes, including CHOP, extended the viability of MAC-T cells pretreated with 5-ALA and also reduced the enhanced intensity of the PA-induced expression of phospho-protein kinase R-like ER kinase. Moreover, the enhanced expression of HO-1 (antioxidant gene heme oxygenase) by 5-ALA reduced PA-induced oxidative stress (OxS). HO-1 is not only protective against OxS but also effective against ER stress. Collectively, these findings offer new insights into the protective effects of 5-ALA against PA-induced apoptosis of bovine MECs.

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.

Porcine epidemic diarrhea virus infections induce autophagy in Vero cells via ROS-dependent endoplasmic reticulum stress through PERK and IRE1 pathways

Porcine epidemic diarrhea virus (PEDV), the causative agent of PED, belongs to the genus Alphacoronavirus in the family Coronaviridae. Reactive oxygen species (ROS), endoplasmic reticulum (ER) stress, and autophagy play crucial roles in regulating a variety of cellular processes during viral infection. However, the precise role of autophagy in PEDV-infected Vero cells remains largely elusive. To elucidate how PEDV infection induces autophagy, this study ascertained whether ER stress was present in PEDV-infected Vero cells. The results showed PEDV infection significantly increased the expression of GRP78 and LC3Ⅱ. Treatment with the ER stress inhibitor 4-phenylbutyrate (4-PBA) could significantly inhibit PEDV-induced autophagy. Antioxidants, such as N-acetylcysteine (NAC), could significantly inhibit PEDV-induced ER stress and autophagy, indicating that ROS act as an upstream regulator of ER stress-mediated autophagy. Further research found that activation of ER stress triggered the unfolded protein response (UPR) through PERK, IRE1, and ATF6 pathways during PEDV infection. However, treatment with the PERK inhibitor GSK2606414, IRE1 inhibitor STF-083010 but not ATF6 inhibitor AEBSF reversed PEDV-induced autophagy. Taken together, the results of this study showed that accumulated ROS played an essential role in regulating ER stress-mediated autophagy during PEDV infection. We also found that PERK and IER1 pathways of UPR signalling were involved in PEDV-induced autophagy. Furthermore, PEDV induced autophagy to promote viral replication via PERK and IER1 pathways in Vero cells. These results provide the mechanism of PEDV-induced ROS-dependent ER stress-mediated autophagy in Vero cells through activating PERK and IRE1 pathways.

Continuous treatment with cisplatin induces the oocyte death of primordial follicles without activation

Chemotherapy directly or indirectly affects organs in a short-term or continuous manner. Endocrine organs are especially sensitive to cancer treatment, leading to concerns among patients regarding their quality of life afterward. Side effects to the ovary include damage to the ovarian reserve, resulting in follicle loss, endocrine hormone deficiency, and infertility. It has been previously demonstrated that continuous treatment with 2 mg/kg cisplatin for 15 days can activate primordial follicles, suggesting that the response in the oocytes of primordial follicles was dependent on cisplatin concentration and administration frequency. However, our results demonstrate that continuous treatment with 2 mg/kg cisplatin for 15 days leads to the same consequence as with the continuous treatment of 5 mg/kg cisplatin: the death of oocytes in primordial follicles without indication of activation. Moreover, animals co-injected with melatonin and cisplatin did not display any significant differences from those treated with cisplatin only contrary to the known results. 6-hydroxymelatonin, a metabolite of melatonin, could not prevent follicle destruction, implying that melatonin does not confer the protection of ovarian follicles, either directly or indirectly. Altogether, our data support that fertoprotectants against cisplatin must target molecules that control cell death pathways in the oocytes of primordial follicles.

Rosiglitazone ameliorates palmitic acid-induced endoplasmic reticulum stress and steroidogenic capacity in granulosa cells

Granulosa cells play essential roles in follicular development, oocyte maturation and sex hormone secretion. The exposure of granulosa cells to palmitic acid (PA), the main component of dietary saturated fat, inhibits cell viability. However, the mechanism underlying PA-induced cytotoxicity in granulosa cells has not been deeply investigated. Rosiglitazone (RSG) is a member of the thiazolidinedione family and is reported to protect cells from cytotoxicity and endoplasmic reticulum (ER) stress in other cell types, but whether RSG protects granulosa cells remain unknown. In this study, KGN cell line and primary granulosa cells were used as models of granulosa cells to explore the effects of PA and RSG and the underlying mechanisms. The results showed that PA inhibits cell viability and estradiol secretion through inducing ER stress and cAMP/PKA/CREB pathway. CCAAT/enhancer-binding protein homologous protein (CHOP), an ER stress marker, was demonstrated to participate in PA-induced cytotoxicity. RSG treatment rescued granulosa cells from PA-induced cell death and ER stress. Moreover, RSG was identified to ameliorate ER stress induced by tunicamycin in granulosa cells. In addition, RSG treatment rescued granulosa cells from PA-induced decrease of estrogen secretion by cAMP/PKA/CREB pathway. In conclusion, RSG can protect granulosa cells against PA-induced cytotoxicity by inhibiting ER stress, and can recover steroidogenic capacity, indicating a potential use of RSG in the treatment of granulosa cell dysfunction.

Non-esterified fatty acids in the ovary: friends or foes?

A majority of common metabolic diseases can result in excessive lipolysis, leading to elevated levels of non-esterified fatty acids (NEFAs) in the body fluids. In females, increased NEFA levels in the follicular fluid markedly alter the functions of intrafollicular cells such as granulosa cells (GCs) and oocytes. Therefore, elevated levels of NEFAs have been suggested to be a significant player of subfertility in females of both human and economically important animal species such as cattle, buffalo, sheep, pig, chicken, and dog. However, the effects imposed by saturated and unsaturated fatty acids (SFAs and UFAs) on ovarian follicles are controversial. The present review emphasizes that SFAs induce apoptosis in granulosa and cumulus cells of ovarian follicles in different species. They further could adversely affect oocyte maturation and developmental competence. Many types of UFAs affect steroidogenesis and proliferation processes and could be detrimental for follicular cells, especially when at elevated concentrations. Interestingly, monounsaturated fatty acids (MUFAs) appear to contribute to the etiology of the polycystic ovarian syndrome (PCOS) as they were found to induce the transcription and translation of the androgenic transcription factor SOX9 while downregulating its estrogenic counterpart FOXL2 in GCs. Overall, this review presents our revised understanding of the effects of different fatty acids on the female reproductive success, which may allow other researchers and clinicians to investigate the mechanisms for treating metabolic stress-induced female infertility.

Protective effect of melatonin against methotrexate-induced testicular damage in the rat model: An experimental study

Background

Methotrexate (MTX) has been shown to affect the testes adversely, especially the seminiferous epithelium. As melatonin, an endocrine hormone, has been shown to normalize testicular function, its ability to prevent MTX-induced testicular damage should be considered.

Objective

Based on the antioxidant, anti-inflammatory, and antiapoptotic activities of melatonin, this study aimed to investigate its protective effect against testicular damage induced by MTX.

Materials and Methods

Forty adult male rats (200-230 g) were divided into five groups (n = 8/each). The rats in group I were injected with vehicle as a control. In group II, the rats were received intraperitoneal injections of melatonin (8 mg/kg) for 15 consecutive days. The rats in group III were intravenously injected with MTX (75 mg/kg) for 15 consecutive days. The remaining two groups received melatonin (8 mg/kgBW) for 15 (group IV) and 30 (group V) consecutive days, intraperitoneally, and then intravenously received MTX (75 mg/kgBW) on days 8 and 15 of the experimental period. Reproductive parameters, including epididymal sperm concentration, testicular tyrosine-phosphorylated protein expression, steroidogenic acute regulatory (StAR) protein expression, and caspase-3 and malondialdehyde levels, were examined.

Results

The sperm concentrations ( × 10 6 /ml) of groups IV (58.75 ± 1.28) and V (55.93 ± 2.57) were improved significantly (p = 0.032) compared with that of group II (32.92 ± 2.14). The seminiferous epithelium in groups IV and V also increased, while caspase-3 expression decreased. In the melatonin-treated groups, the expression of tyrosine-phosphorylated proteins at 32 kDa was decreased and that of proteins at 47 kDa was increased compared with the MTX group. StAR protein expression was not altered in any of the groups.

Conclusion

Our results indicate that melatonin improves the epididymal sperm concentration by decreasing the expression of caspase-3 and increasing that of tyrosine-phosphorylated proteins in MTX-treated testes.

Quercetin Protects Against Lipopolysaccharide-Induced Intestinal Oxidative Stress in Broiler Chickens through Activation of Nrf2 Pathway

We investigated the potential ability of quercetin to protect against lipopolysaccharide (LPS)-induced intestinal oxidative stress in broiler chickens and the potential role of the Nrf2 (nuclear factor erythroid 2-related factor 2) signaling pathway. One-day-old broiler chickens (n = 240) were randomized into four groups: saline-challenged broiler chickens fed a basal diet (Con), LPS-challenged broiler chickens on a basal diet (LPS), and LPS-treated broiler chickens on a basal diet containing either 200 or 500 mg/kg of quercetin (Que200+LPS or Que500+LPS). Quercetin (200 mg/kg) significantly alleviated LPS-induced decreased duodenal, jejunal, and illeal villus height and increased the crypt depth in these regions. Quercetin significantly inhibited LPS-induced jejunal oxidative stress, including downregulated reactive oxygen species (ROS), malondialdehyde (MDA), and 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels, and it upregulated superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) levels. Quercetin relieved LPS-induced jejunal mitochondria damage and upregulated mitochondrial DNA copy number-related gene expression, including cytochrome c oxidase subunit 1 (COX1), ATP synthase F0 subunit 6 (ATP6), and NADH dehydrogenase subunit 1 (ND1). Quercetin attenuated the LPS-induced inhibition of Nrf2 activation, translocation, and downstream gene expression, including heme oxygenase-1 (HO-1), NAD (P) H dehydrogenase quinone 1 (NQO1), and manganese superoxide dismutase (SOD2). Additionally, quercetin attenuated the LPS-inhibition of c-Jun N-terminal kinase (JNK), Extracellular Regulated protein Kinases (ERK), and p38MAPK (p38) phosphorylation in the MAPK pathway. Thus, quercetin attenuated LPS-induced oxidative stress in the intestines of broiler chickens via the MAPK/Nrf2 signaling pathway.

Excessive oxidative stress in cumulus granulosa cells induced cell senescence contributes to endometriosis-associated infertility

Endometriosis an important cause of female infertility and seriously impact physical and psychological health of patients. Endometriosis is now considered to be a public health problem that deserves in-depth investigation, especially the etiopathogenesis of endometriosis-associated infertility. We aimed to illuminate the etiopathogenesis of endometriosis-associated infertility that involve excessive oxidative stress (OS) induced pathological changes of ovary cumulus granulosa cell (GCs). Senescence-associated β-galactosidase (SA β-gal) activity in GCs from endometriosis patients, soluble isoform of advanced glycation end products receptor (sRAGE) expression in follicular fluid from endometriosis patients and differentially expressed senescence-associated secretory phenotype factors (IL-1β, MMP-9, KGF and FGF basic protein) are all useful indexes to evaluate oocyte retrieval number and mature oocyte number. RNA-sequencing and bioinformatics analysis indicated senescent phenotype of endometriosis GCs and aggravated endoplasmic reticulum (ER) stress in endometriosis GCs. Targeting ER stress significantly alleviated OS-induced GCs senescence as well as mitochondrial membrane potential (MMP) and adenosine triphosphate (ATP) reduction in GCs. Moreover, melatonin administration rescued OS-enhanced ER stress, cellular senescence, and MMP and ATP abnormities of endometriosis GCs in vitro and in vivo. In conclusion, our results indicated excessive reactive oxygen species induces senescence of endometriosis GCs via arouse ER stress, which finally contributes to endometriosis-associated infertility, and melatonin may represent a novel adjuvant therapy strategy for endometriosis-associated infertility.

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Endometriosis patients ovary cumulus granulosa cells (GCs) show senescence phenotype.

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Excessive oxidative stress in GCs drives cellular senescence via activating ER stress.

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Melatonin alleviates ER stress and GCs senescence in vitro and in vivo.

P65 Targets FGFR1 to Regulate the Survival of Ovarian Granulosa Cells

In female mammals, the abnormal apoptosis of ovarian granulosa cells (GCs) impairs follicular development and causes reproductive dysfunction. Many studies have indicated that the FGFR1 gene of the PI3K signaling pathway and the p65 subunit of the transcription factor NF-κB may regulate the proliferation and apoptosis of GCs involved in follicular development. However, little is known about whether p65 regulates the transcription of FGFR1, as well as the biological effects of p65 and FGFR1 on the survival of GCs and follicular development. In porcine follicles and GCs, we found that p65 and FGFR1 were exclusively expressed in the GCs of follicles, and the mRNA and protein levels of p65 and FGFR1 significantly increased from small to large follicles. Both p65 and FGFR1 were found to activate the PI3K signaling pathway, and the expressions of proliferation markers (PCNA and MKI67) and the anti-apoptotic gene BCL2 were significantly increased by p65 and FGFR1. Furthermore, both p65 and FGFR1 were observed to promote cell proliferation and inhibit the cell apoptosis of GCs, and p65 was confirmed to bind at the −348/−338 region of FGFR1 to positively regulate its transcription. Moreover, p65 was further found to enhance the pro-proliferation and anti-apoptotic effects of FGFR1. Taken together, p65 may target the −348/−338 region of FGFR1, promote the transcription of FGFR1, and enhance the pro-proliferation effect and anti-apoptotic effect of FGFR1 to facilitate the growth of follicles. This study will provide useful information for further investigations on the p65-mediated-FGFR1 signaling pathway during folliculogenesis in mammals.

Melatonin Inhibits Apoptosis and Oxidative Stress of Mouse Leydig Cells via a SIRT1-Dependent Mechanism

The purpose of the present study is to examine the effects of melatonin on apoptosis and oxidative stress in mouse Leydig cells and to elucidate the mechanisms responsible for these effects. Our results indicated that 10 ng/mL of melatonin significantly promoted cell viability, the ratio of EdU-positive (5-Ethynyl-2'-deoxyuridine) cells, and increased the mRNA expression of proliferating cell nuclear antigen (PCNA), cyclin D1(CCND1), and cell division control protein 42 (CDC42) (p < 0.05). We also observed that melatonin inhibited apoptosis of mouse Leydig cells, accompanied with increased B-cell lymphoma-2 (BCL-2) and decreased BCL2 associated X (BAX) mRNA and protein expression. Moreover, addition of melatonin significantly decreased the reactive oxygen species (ROS) production and malondialdehyde (MDA) and 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels, while it increased superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) levels (p < 0.05). In addition, we also found that melatonin increased the expression of SIRT1 (Silent information regulator 1) (p < 0.05). To explore the role of SIRT1 signaling in melatonin-induced cells, mouse Leydig cells were pretreated with EX527, an inhibitor of SIRT1. The protective effects of melatonin on mouse Leydig cells were reversed by EX527, as shown by decreased cell proliferation and increased cell apoptosis and oxidative stress. In summary, our results demonstrated that melatonin inhibited apoptosis and oxidative stress of mouse Leydig cells through a SIRT1-dependent mechanism.

Role of endoplasmic reticulum stress in lipopolysaccharide-inhibited mouse granulosa cell estradiol production

The decrease in the level of estradiol (E₂) in granulosa cells caused by lipopolysaccharide (LPS) is one of the major causes of infertility underlying postpartum uterine infections; the precise molecular mechanism of which remains elusive. This study investigated the role of endoplasmic reticulum (ER) stress in LPS-induced E₂ decrease in mouse granulosa cells. Our results showed that LPS increased the pro-inflammatory cytokines [(interleukin (IL)-1β, IL-6, IL-8, and tumor necrosis factor (TNF)-α)], activated ER stress marker protein expression [(glucose-regulated protein 78 (GRP78) and CCAAT/enhancer-binding protein homologous protein (CHOP)], and decreased cytochrome P450 family 19 subfamily A member 1 (Cyp19a1) expression and E₂ production. Moreover, inhibition of ER stress by 4-phenylbutyrate (4-PBA) attenuated thapsigargin-(TG, ER stress agonist) or LPS-induced reduction of Cyp19a1 and E₂, pro-inflammatory cytokines expression (IL-1β, IL-6, IL-8, and TNF-α), and the expression of CHOP and GRP78. Additionally, inhibition of toll-like receptor 4 (TLR4) by resatorvid (TAK-242) reversed the inhibitory effects of LPS on Cyp19a1 expression and E₂ production, activation of GRP78 and CHOP, and expression of IL-1β, IL-6, IL-8, and TNF-α. In summary, our study suggests that ER stress is involved in LPS-inhibited E₂ production in mouse granulosa cells.