Bisphenol A-elicited miR-146a-5p impairs murine testicular steroidogenesis through negative regulation of Mta3 signaling

Bisphenol A: Epigenetic effects on the male reproductive system and male offspring

Bisphenol A (BPA) is a commonly used organic compound. Over the past decades, many studies have examined the mechanisms of BPA toxicity, with BPA-induced alterations in epigenetic modifications receiving considerable attention. Particularly in the male reproductive system, abnormal alterations in epigenetic markers can adversely affect reproductive function. Furthermore, these changes in epigenetic markers can be transmitted to offspring through the father. Here, we review the effects of BPA exposure on various epigenetic markers in the male reproductive system, including DNA methylation, histone modifications, and noncoding RNA, as well as associated changes in the male reproductive function. We also reviewed the effects of father's exposure to BPA on offspring epigenetic modification patterns.

Emerging regulatory roles of noncoding RNAs induced by bisphenol a (BPA) and its alternatives in human diseases

Bisphenols (BPs), including BPA, BPF, BPS, and BPAF, are synthetic phenolic organic compounds and endocrine-disrupting chemicals. These organics have been broadly utilized to produce epoxy resins, polycarbonate plastics, and other products. Mounting evidence has shown that BPs, especially BPA, may enter into the human body and participate in the development of human diseases mediated by nuclear hormone receptors. Moreover, BPA may negatively affect human health at the epigenetic level through processes such as DNA methylation and histone acetylation. Recent studies have demonstrated that, as part of epigenetics, noncoding RNAs (ncRNAs), including microRNAs (miRNAs), long noncoding RNAs (lncRNAs), circular RNAs (circRNAs), and small nucleolar RNAs (snoRNAs), have vital impacts on BP-related diseases, such as reproductive system diseases, nervous system diseases, digestive system diseases, endocrine system diseases, and other diseases. Moreover, based on the bioinformatic analysis, changes in ncRNAs may be relevant to normal activities and functions and BP-induced diseases. Thus, we conducted a meta-analysis to identify more promising ncRNAs as biomarkers and therapeutic targets for BP exposure and relevant human diseases. In this review, we summarize the regulatory functions of ncRNAs induced by BPs in human diseases and latent molecular mechanisms, as well as identify prospective biomarkers and therapeutic targets for BP exposure and upper diseases.

Adverse effects of bisphenol A and its analogues on male fertility: An epigenetic perspective

In recent years, there has been growing concern about the adverse effects of endocrine disrupting chemicals (EDCs) on male fertility. Epigenetic modification is critical for male germline development, and has been suggested as a potential mechanism for impaired fertility induced by EDCs. Bisphenol A (BPA) has been recognized as a typical EDC. BPA and its analogues, which are still widely used in various consumer products, have garnered increasing attention due to their reproductive toxicity and the potential to induce epigenetic alteration. This literature review provides an overview of studies investigating the adverse effects of bisphenol exposures on epigenetic modifications and male fertility. Existing studies provide evidence that exposure to bisphenols can lead to adverse effects on male fertility, including declined semen quality, altered reproductive hormone levels, and adverse reproductive outcomes. Epigenetic patterns, including DNA methylation, histone modification, and non-coding RNA expression, can be altered by bisphenol exposures. Transgenerational effects, which influence the fertility and epigenetic patterns of unexposed generations, have also been identified. However, the magnitude and direction of certain outcomes varied across different studies. Investigations into the dynamics of histopathological and epigenetic alterations associated with bisphenol exposures during developmental stages can enhance the understanding of the epigenetic effects of bisphenols, the implication of epigenetic alteration on male fertility, and the health of successive generation.

Attenuated AKT signaling by miR-146a-5p interferes with chicken granulosa cell proliferation, lipid deposition and progesterone biosynthesis

Steroid hormones play a crucial role in the growth and maturation of poultry ovarian follicles, with progesterone secretion by granulosa cells (GC) being essential. According to our previous transcriptome analysis, it apparented that miR-146a-5p expressions were upregulated in the follicles undergoing atresia. In this study, we delved the depth to explore the underlying mechanisms by miR-146a-5p in the regulation of follicle functions in chicken. The study demonstrated that miR-146a-5p suppressed cell growth, lipids accumulation, and progesterone biosynthesis in chicken GC. Through targeting association validations, we identified delta 4-desaturase, sphingolipid 1 (DEGS1) as capable of interacting with miR-146a-5p. Co-transfection experiments further confirmed that DEGS1 reversed the impairment of GC functions by miR-146a-5p. Moreover, we discovered that miR-146a-5p suppressed AKT phosphorylation, while DEGS1 enhanced AKT phosphorylation. Phosphatidylinositol-3 kinase (PI3K) inhibitor (LY294002) studies showed that miR-146a-5p would inhibit AKT phosphorylation by governing the DEGS1/AKT pathway, which in turn regulates GC function. In summary, the findings revealed that miR-146a-5p suppressed cell growth, lipid deposition, and progesterone biosynthesis via the DEGS1/AKT pathway. These results may further enrich our understandings of how non-coding RNA regulates productive performance in chickens.

Human Umbilical Cord Mesenchymal Stem Cell-Derived Exosomes Rescue Testicular Aging

BACKGROUND

Testicular aging is associated with diminished fertility and certain age-related ailments, and effective therapeutic interventions remain elusive. Here, we probed the therapeutic efficacy of exosomes derived from human umbilical cord mesenchymal stem cells (hUMSC-Exos) in counteracting testicular aging.

METHODS

We employed a model of 22-month-old mice and administered intratesticular injections of hUMSC-Exos. Comprehensive analyses encompassing immunohistological, transcriptomic, and physiological assessments were conducted to evaluate the effects on testicular aging. Concurrently, we monitored alterations in macrophage polarization and the oxidative stress landscape within the testes. Finally, we performed bioinformatic analysis for miRNAs in hUMSC-Exos.

RESULTS

Our data reveal that hUMSC-Exos administration leads to a marked reduction in aging-associated markers and cellular apoptosis while promoting cellular proliferation in aged testis. Importantly, hUMSC-Exos facilitated the restoration of spermatogenesis and elevated testosterone synthesis in aged mice. Furthermore, hUMSC-Exos could attenuate inflammation by driving the phenotypic shift of macrophages from M1 to M2 and suppress oxidative stress by reduced ROS production. Mechanistically, these efficacies against testicular aging may be mediated by hUMSC-Exos miRNAs.

CONCLUSIONS

Our findings suggest that hUMSC-Exos therapy presents a viable strategy to ameliorate testicular aging, underscoring its potential therapeutic significance in managing testicular aging.

MicroRNA‑30a‑5p regulates cypermethrin-induced apoptosis of Sertoli cells by targeting KLF9 in vitro

Cypermethrin (CYP) has been identified as one kind of endocrine-disrupting chemicals (EDCs) to induce male reproduction damage. This study aimed to investigate the effects and mechanisms of miR-30a-5p on CYP induced apoptosis of TM4 mouse Sertoli cells in vitro. In the present study, 0 μM, 10 μM, 20 μM, 40 μM and 80 μM CYP were used to treat TM4 cells for 24 h. The apoptosis of TM4 cells, the expression level of miR-30a-5p, the protein expressions and the interaction between miR-30a-5p and KLF9 were detected by flow cytometry, quantitative Real-Time PCR, Western blot and luciferase reporter assays. CYP induced apoptosis of TM4 cells, inhibited expression of miR-30a-5p in TM4 cells, and overexpression of miR-30a-5p partially recovered CYP induced cells apoptosis. Furthermore, KLF9 was a potential downstream target of miR-30a-5p predicted by publicly available databases. KLF9 expression level in TM4 cells was significantly elevated after treatment with CYP, and the induction was inhibited by miR-30a-5p mimics transfection. Meanwhile, dual-luciferase reporter assay demonstrated that miR-30a-5p directly targeted KLF9-3'UTR. Moreover, in the presence of CYP, the apoptosis regulator p53 expression was also increased in TM4 cells. Overexpression miR-30a-5p or down-regulation of KLF9 both attenuated the induction of CYP on p53 expression. Overall, the present study demonstrated that miR-30a-5p regulated CYP induced TM4 cells apoptosis by targeting KLF9/p53 axis.

The State of Research and Weight of Evidence on the Epigenetic Effects of Bisphenol A

Bisphenol A (BPA) is a high-production-volume chemical with numerous industrial and consumer applications. BPA is extensively used in the manufacture of polycarbonate plastics and epoxy resins. The widespread utilities of BPA include its use as internal coating for food and beverage cans, bottles, and food-packaging materials, and as a building block for countless goods of common use. BPA can be released into the environment and enter the human body at any stage during its production, or in the process of manufacture, use, or disposal of materials made from this chemical. While the general population is predominantly exposed to BPA through contaminated food and drinking water, non-dietary exposures through the respiratory system, integumentary system, and vertical transmission, as well as other routes of exposure, also exist. BPA is often classified as an endocrine-disrupting chemical as it can act as a xenoestrogen. Exposure to BPA has been associated with developmental, reproductive, cardiovascular, neurological, metabolic, or immune effects, as well as oncogenic effects. BPA can disrupt the synthesis or clearance of hormones by binding and interfering with biological receptors. BPA can also interact with key transcription factors to modulate regulation of gene expression. Over the past 17 years, an epigenetic mechanism of action for BPA has emerged. This article summarizes the current state of research on the epigenetic effects of BPA by analyzing the findings from various studies in model systems and human populations. It evaluates the weight of evidence on the ability of BPA to alter the epigenome, while also discussing the direction of future research.

Re-evaluation of the risks to public health related to the presence of bisphenol A (BPA) in foodstuffs

In 2015, EFSA established a temporary tolerable daily intake (t-TDI) for BPA of 4 μg/kg body weight (bw) per day. In 2016, the European Commission mandated EFSA to re-evaluate the risks to public health from the presence of BPA in foodstuffs and to establish a tolerable daily intake (TDI). For this re-evaluation, a pre-established protocol was used that had undergone public consultation. The CEP Panel concluded that it is Unlikely to Very Unlikely that BPA presents a genotoxic hazard through a direct mechanism. Taking into consideration the evidence from animal data and support from human observational studies, the immune system was identified as most sensitive to BPA exposure. An effect on Th17 cells in mice was identified as the critical effect; these cells are pivotal in cellular immune mechanisms and involved in the development of inflammatory conditions, including autoimmunity and lung inflammation. A reference point (RP) of 8.2 ng/kg bw per day, expressed as human equivalent dose, was identified for the critical effect. Uncertainty analysis assessed a probability of 57-73% that the lowest estimated Benchmark Dose (BMD) for other health effects was below the RP based on Th17 cells. In view of this, the CEP Panel judged that an additional uncertainty factor (UF) of 2 was needed for establishing the TDI. Applying an overall UF of 50 to the RP, a TDI of 0.2 ng BPA/kg bw per day was established. Comparison of this TDI with the dietary exposure estimates from the 2015 EFSA opinion showed that both the mean and the 95th percentile dietary exposures in all age groups exceeded the TDI by two to three orders of magnitude. Even considering the uncertainty in the exposure assessment, the exceedance being so large, the CEP Panel concluded that there is a health concern from dietary BPA exposure.

Role of microRNA in Endocrine Disruptor-Induced Immunomodulation of Metabolic Health

The prevalence of poor metabolic health is growing exponentially worldwide. This condition is associated with complex comorbidities that lead to a compromised quality of life. One of the contributing factors recently gaining attention is exposure to environmental chemicals, such as endocrine-disrupting chemicals (EDCs). Considerable evidence suggests that EDCs can alter the endocrine system through immunomodulation. More concerning, EDC exposure during the fetal development stage has prominent adverse effects later in life, which may pass on to subsequent generations. Although the mechanism of action for this phenomenon is mostly unexplored, recent reports implicate that non-coding RNAs, such as microRNAs (miRs), may play a vital role in this scenario. MiRs are significant contributors in post-transcriptional regulation of gene expression. Studies demonstrating the immunomodulation of EDCs via miRs in metabolic health or towards the Developmental Origins of Health and Disease (DOHaD) Hypothesis are still deficient. The aim of the current review was to focus on studies that demonstrate the impact of EDCs primarily on innate immunity and the potential role of miRs in metabolic health.

Genetic, epigenetic and enviromental influencing factors on the regulation of precocious and delayed puberty

The pubertal development onset is controlled by a network of genes that regulate the gonadotropin releasing hormone (GnRH) pulsatile release and the subsequent increase of the circulating levels of pituitary gonadotropins that activate the gonadal function. Although the transition from pre-pubertal condition to puberty occurs physiologically in a delimited age-range, the inception of pubertal development can be anticipated or delayed due to genetic and epigenetic changes or environmental conditions. Most of the genetic and epigenetic alterations concern genes which encode for kisspeptin, GnRH, LH, FSH and their receptor, which represent crucial factors of the hypothalamic-pituitary-gonadal (HPG) axis. Recent data indicate a central role of the epigenome in the regulation of genes in the hypothalamus and pituitary that could mediate the flexibility of pubertal timing. Identification of epigenetically regulated genes, such as Makorin ring finger 3 (MKRN3) and Delta-like 1 homologue (DLK1), respectively responsible for the repression and the activation of pubertal development, provides additional evidence of how epigenetic variations affect pubertal timing. This review aims to investigate genetic, epigenetic, and environmental factors responsible for the regulation of precocious and delayed puberty.

WGCNA Analysis Identifies Polycystic Ovary Syndrome-Associated Circular RNAs That Interact with RNA-Binding Proteins and Sponge miRNAs

Objective

Dysfunction of cumulus granulosa cells has been suggested as a contributor to abnormal folliculogenesis and the development of polycystic ovary syndrome (PCOS), but the underlying molecular mechanisms remain unclear. Recent studies indicate that circular RNAs (circRNAs) exert important roles for diseases. We aimed to screen crucial circRNAs of PCOS patients and predict their functions.

Methods

The high-throughput datasets of circRNAs (GSE145296), microRNAs (miRNAs; GSE72274) and messenger RNAs (mRNAs; GSE155489) in cumulus cells of PCOS patients and controls were collected from the Gene Expression Omnibus database. Differentially expressed circRNAs (DECs), miRNAs (DEMs) and protein-coding genes (DEGs) were identified by the limma method. The weighted correlation network analysis (WGCNA) was conducted using the DECs to mine PCOS-associated modules. Hub DECs in modules were defined as both of |gene significance| and |module membership| >0.8. The downstream effectors of hub DECs were predicted by constructing DEC-DEM-DEG ceRNA and DEC-RNA binding protein (RBP) networks. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses were performed to explore the functions of circRNAs.

Results

A total of 3614 DECs, 3544 DEGs and 1469 DEMs were identified between PCOS and controls. WGCNA analysis yielded five PCOS-related modules, of which 190 DECs were hub circRNAs. Seventeen hub DECs, nine DEMs, and 315 DEGs were identified to construct the ceRNA network, while 56 hub DECs and two DEGs (MBNL2, RBPMS) constituted the circRNA-RBP network. Five hub DECs (hsa_circ_0063309, hsa_circ_0054275, hsa_circ_0056196, hsa_circ_0018108 and hsa_circ_0070987) were overlapped between ceRNA and DEC-MBNL2 regulatory networks and thus they may be pivotal for PCOS. Furthermore, hsa_circ_0099109 could interact with the RBP gene RBPMS. Function analyses showed these circRNAs were inflammation-, apoptosis- or steroidogenesis-related.

Conclusion

Aberrant expression of six circRNAs that function as RBP regulators or miRNA sponges may be possible mechanisms underlying the pathogenesis of PCOS by affecting apoptosis and steroidogenesis in cumulus cells.

miRNA changes in the mouse placenta due to bisphenol A exposure

Aim: To determine small RNA expression changes in mouse placenta induced by bisphenol A (BPA) exposure. Methods: Exposing female mice to BPA two weeks prior to conception through gestational day 12.5; whereupon fetal placentas were collected, frozen in liquid nitrogen and stored at -80°C. Small RNAs were isolated and used for small RNA-sequencing. Results: 43 small RNAs were differentially expressed. Target mRNAs were closely aligned to those expressed by thymus and brain, and pathway enrichment analyses indicated that such target mRNAs regulate neurogenesis and associated neurodevelopment processes. Conclusions: BPA induces several small RNAs in mouse placenta that might provide biomarkers for BPA exposure. Further, the placenta might affect fetal brain development through the secretion of miRNAs.

Transcriptomics and Other Omics Approaches to Investigate Effects of Xenobiotics on the Placenta

The conceptus is most vulnerable to developmental perturbation during its early stages when the events that create functional organ systems are being launched. As the placenta is in direct contact with maternal tissues, it readily encounters any xenobiotics in her bloodstream. Besides serving as a conduit for solutes and waste, the placenta possesses a tightly regulated endocrine system that is, of itself, vulnerable to pharmaceutical agents, endocrine disrupting chemicals (EDCs), and other environmental toxicants. To determine whether extrinsic factors affect placental function, transcriptomics and other omics approaches have become more widely used. In casting a wide net with such approaches, they have provided mechanistic insights into placental physiological and pathological responses and how placental responses may impact the fetus, especially the developing brain through the placenta-brain axis. This review will discuss how such omics technologies have been utilized to understand effects of EDCs, including the widely prevalent plasticizers bisphenol A (BPA), bisphenol S (BPS), and phthalates, other environmental toxicants, pharmaceutical agents, maternal smoking, and air pollution on placental gene expression, DNA methylation, and metabolomic profiles. It is also increasingly becoming clear that miRNA (miR) are important epigenetic regulators of placental function. Thus, the evidence to date that xenobiotics affect placental miR expression patterns will also be explored. Such omics approaches with mouse and human placenta will assuredly provide key biomarkers that may be used as barometers of exposure and can be targeted by early mitigation approaches to prevent later diseases, in particular neurobehavioral disorders, originating due to placental dysfunction.

Endocrine-disrupting chemicals and their effects on puberty

Sexual maturation in humans is characterized by a unique individual variability. Pubertal onset is a highly heritable polygenic trait but it is also affected by environmental factors such as obesity or endocrine disrupting chemicals. The last 30 years have been marked by a constant secular trend toward earlier age at onset of puberty in girls and boys around the world. More recent data, although more disputed, suggest an increased incidence in idiopathic central precocious puberty. Such trends point to a role for environmental factors in pubertal changes. Animal data suggest that the GnRH-neuronal network is highly sensitive to endocrine disruption during development. This review focuses on the most recent data regarding secular trend in pubertal timing as well as potential new epigenetic mechanisms explaining the developmental and transgenerational effects of endocrine disrupting chemicals on pubertal timing.

What Does CLARITY-BPA Mean for Canadians?

Bisphenol A is an extremely high-volume chemical widely used in polycarbonate plastics, the linings of food and beverage tins, and shopping receipts. Canadians are ubiquitously exposed to bisphenol A and research shows that exposure at environmentally relevant doses causes endocrine disruption. Recent risk assessments and exposure estimates by the European Food Safety Authority have guided increased restrictions around the use of bisphenol A and established a lower tolerable daily intake, while the CLARITY-BPA program in the United States identified several adverse effects below this exposure level. Within the context of bisphenol toxicity and international regulation, this paper describes the need for revised bisphenol A risk assessments in Canada. Completed in 2008, the most recent bisphenol A risk assessment conducted by Health Canada does not include risks from alternative bisphenols or non-dietary exposure. It also does not account for the additive effects caused by simultaneous exposure to multiple endocrine-disrupting chemicals.

Cellular and molecular features of EDC exposure: consequences for the GnRH network

The onset of puberty and the female ovulatory cycle are important developmental milestones of the reproductive system. These processes are controlled by a tightly organized network of neurotransmitters and neuropeptides, as well as genetic, epigenetic and hormonal factors, which ultimately drive the pulsatile secretion of gonadotropin-releasing hormone. They also strongly depend on organizational processes that take place during fetal and early postnatal life. Therefore, exposure to environmental pollutants such as endocrine-disrupting chemicals (EDCs) during critical periods of development can result in altered brain development, delayed or advanced puberty and long-term reproductive consequences, such as impaired fertility. The gonads and peripheral organs are targets of EDCs, and research from the past few years suggests that the organization of the neuroendocrine control of reproduction is also sensitive to environmental cues and disruption. Among other mechanisms, EDCs interfere with the action of steroidal and non-steroidal receptors, and alter enzymatic, metabolic and epigenetic pathways during development. In this Review, we discuss the cellular and molecular consequences of perinatal exposure (mostly in rodents) to representative EDCs with a focus on the neuroendocrine control of reproduction, pubertal timing and the female ovulatory cycle.

Disruption of global hypothalamic microRNA (miR) profiles and associated behavioral changes in California mice (Peromyscus californicus) developmentally exposed to endocrine disrupting chemicals

Developmental exposure to endocrine disrupting chemicals (EDCs), e.g., bisphenol A (BPA) or genistein (GEN), causes longstanding epigenome effects. MicroRNAs (miRs) regulate which mRNAs will be translated to proteins and thereby serve as the final checkpoint in epigenetic control. Scant amount is known, however, whether EDCs affect neural miRNA (miR) patterns. We aimed to test the hypothesis that developmental exposure of California mice (Peromyscus californicus) to GEN, BPA, or both chemicals influences hypothalamic miR/small RNA profiles and ascertain the extent such biomolecular alterations correlate with behavioral and metabolic changes. California mice were developmentally exposed to GEN (250 mg/kg feed weight, FW), GEN (250 mg/kg FW)+BPA (5 mg/kg FW), low dose (LD) BPA (5 mg/kg FW), or upper dose (UD) BPA (50 mg/kg FW). Adult offspring were tested in a battery of behavioral and metabolic tests; whereupon, mice were euthanized, brains were collected and frozen, small RNAs were isolated from hypothalamic punches, and subsequently sequenced. California mice exposed to one or both EDCs engaged in one or more repetitive behaviors. GEN, LD BPA, and UD BPA altered aspects of ultrasonic and audible vocalizations. Each EDC exposure led to sex-dependent differences in differentially expressed miR/small RNAs with miR7-2, miR146, and miR148a being increased in all female and male EDC exposed groups. Current findings reveal that developmental exposure to GEN and/or BPA affects hypothalamic miR/small RNA expression patterns, and such changes correlate with EDC-induced behavioral and metabolic alterations. miR146 is likely an important mediator and biomarker of EDC exposure in mammals, including humans.

The role of epigenetics in the reproductive toxicity of environmental endocrine disruptors

Environmental endocrine disruptors (EEDs) seriously endanger human health by interfering with the normal function of reproductive systems. In males, EEDs can affect sperm formation and semen quality as well spermatogenesis, ultimately reducing fertility. In females, EEDs can affect uterine development and the expression levels of reproduction-related genes, ultimately reducing female fertility and the normal development of the fetus. There are a large number of putative mechanisms by which EEDs can induce reproductive toxicity, and many studies have shown the involvement of epigenetics. In this review, we summarize the role of DNA methylation, noncoding RNAs, genomic imprinting, chromatin remodeling and histone modification in the reproductive toxicity of EEDs.

Different bisphenols induce non-monotonous changes in miRNA expression and LINE-1 methylation in two cell lines

4,4'-Isopropylidenediphenol (bisphenol A, BPA), a chemical substance that is widely used mainly as a monomer in the production of polycarbonates, in epoxy resins, and in thermal papers, is suspected to cause epigenetic modifications with potentially toxic consequences. Due to its negative health effects, BPA is banned in several products and is replaced by other bisphenols such as bisphenol S and bisphenol F. The present study examined the effects of BPA, bisphenol S, bisphenol F, p,p'-oxybisphenol, and the BPA metabolite BPA β-d-glucuronide on the expression of a set of microRNAs (miRNAs) as well as long interspersed nuclear element-1 methylation in human lung fibroblast and Caco-2 cells. The results demonstrated a significant modulation of the expression of different miRNAs in both cell lines including miR-24, miR-155, miR-21, and miR-146a, known for their regulatory functions of cell cycle, metabolism, and inflammation. At concentrations between 0.001 and 10 µg/ml, especially the data of miR-155 and miR-24 displayed non-monotonous and often significant dose-response curves that were U- or bell-shaped for different substances. Additionally, BPA β-d-glucuronide also exerted significant changes in the miRNA expression. miRNA prediction analysis indicated effects on multiple molecular pathways with relevance for toxicity. Besides, long interspersed nuclear element-1 methylation, a marker for the global DNA methylation status, was significantly modulated by two concentrations of BPA and p,p'-oxybisphenol. This pilot study suggests that various bisphenols, including BPA β-d-glucuronide, affect epigenetic mechanisms, especially miRNAs. These results should stimulate extended toxicological studies of multiple bisphenols and a potential use of miRNAs as markers.

T Lymphocytes and Testicular Immunity: A New Insight into Immune Regulation in Testes

The immune privilege of the testes is necessary to prevent immune attacks to gamete-specific antigens and paternal major histocompatibility complex (MHC) antigens, allowing for normal spermatogenesis. However, infection and inflammation of the male genital tract can break the immune tolerance and represent a significant cause of male infertility. Different T cell subsets have been identified in mammalian testes, which may be involved in the maintenance of immune tolerance and pathogenic immune responses in testicular infection and inflammation. We reviewed the evidence in the published literature on different T subtypes (regulatory T cells, helper T cells, cytotoxic T cells, γδ T cells, and natural killer T cells) in human and animal testes that support their regulatory roles in infertility and the orchitis pathology. While many in vitro studies have indicated the regulation potential of functional T cell subsets and their possible interaction with Sertoli cells, Leydig cells, and spermatogenesis, both under physiological and pathological processes, there have been no in situ studies to date. Nevertheless, the normal distribution and function of T cell subsets are essential for the immune privilege of the testes and intact spermatogenesis, and T cell-mediated immune response drives testicular inflammation. The distinct function of different T cell subsets in testicular homeostasis and the orchitis pathology suggests a considerable potential of targeting specific T cell subsets for therapies targeting chronic orchitis and immune infertility.

Role of GPER-Mediated Signaling in Testicular Functions and Tumorigenesis

Estrogen signaling plays important roles in testicular functions and tumorigenesis. Fifteen years ago, it was discovered that a member of the G protein-coupled receptor family, GPR30, which binds also with high affinity to estradiol and is responsible, in part, for the rapid non-genomic actions of estrogens. GPR30, renamed as GPER, was detected in several tissues including germ cells (spermatogonia, spermatocytes, spermatids) and somatic cells (Sertoli and Leydig cells). In our previous review published in 2014, we summarized studies that evidenced a role of GPER signaling in mediating estrogen action during spermatogenesis and testis development. In addition, we evidenced that GPER seems to be involved in modulating estrogen-dependent testicular cancer cell growth; however, the effects on cell survival and proliferation depend on specific cell type. In this review, we update the knowledge obtained in the last years on GPER roles in regulating physiological functions of testicular cells and its involvement in neoplastic transformation of both germ and somatic cells. In particular, we will focus our attention on crosstalk among GPER signaling, classical estrogen receptors and other nuclear receptors involved in testis physiology regulation.

Effects of BPA on zebrafish gonads: Focus on the endocannabinoid system

Bisphenol A (BPA), a monomer used for polycarbonate manufacture, has been widely reported as an endocrine-disrupting chemical (EDC). Among other alterations, BPA induces reproductive dysfunctionalities. Changes in the endocannabinoid system (ECS) have been recently shown to be associated with reproductive disorders. The ECS is a lipid-based signaling system (cannabinoid receptors, endocannabinoids and enzymatic machinery) involved in several physiological functions. The main goal of the present study was to assess the effects of two environmental concentrations of BPA (10 and 20 μg/L) on the ECS in 1-year old zebrafish gonads. In males, BPA increased the gonadosomatic index (GSI) and altered testicular levels of endocannabinoids as well as reduced the testicular area occupied by spermatogonia. In male liver, exposure to 20 μg/L BPA significantly increased vitellogenin (vtg) transcript levels. In female zebrafish, BPA altered ovarian endocannabinoid levels, elevated hepatic vtg mRNA levels as well as increased the percentage of vitellogenic oocytes in the ovaries. In conclusion, exposure to two environmentally relevant concentrations of BPA altered the ECS and consequently, gonadal function in both male and female zebrafish.

A systematic review of microRNA expression studies with exposure to bisphenol A

Bisphenol A (BPA), as a common industrial component, is generally consumed in the synthesis of polymeric materials. To gain a deeper understanding of the detrimental effects of BPA, BPA-induced microRNA (miRNA) alterations were investigated. A systematic search was performed in the PubMed, SCOPUS and Web of Science databases to evoke relevant published data up to August 10, 2019. We identified altered miRNAs that have been repeated in at least three studies. Moreover, miRNA homology analysis between human and nonhuman species was performed to determine the toxicity signatures of BPA in human exposure. In addition, to reflect the effects of environmental exposure levels of BPA, the study designs were categorized into two groups, including low and high doses according to the previous definitions. In total, 28 studies encountered our criteria and 17 miRNAs were identified that were differentially expressed in at least three independent studies. Upregulating miR-146a and downregulating miR-192, miR-134, miR-27b and miR-324 were found in three studies. MiR-122 and miR-29a were upregulated in four studies after BPA exposure, and miR-21 was upregulated in six studies. The results indicate that BPA at low-level exposures can also alter miRNA expression in response to toxicity. Finally, the miRNA-related pathways showed that BPA seriously can affect human health through various cell signaling pathways, which were predictable and consistent with existing studies. Overall, our findings suggest that further studies should be conducted to examine the role of miRNA level changes in human BPA exposure.

The effects of maternal exposure to BPA during pregnancy on the male reproductive system and the testicular microRNA expression profile

The effect of prenatal bisphenol A (BPA) exposure is increasingly concerned. We investigated the effect of maternal BPA exposure during pregnancy on male offspring and its potential mechanism. Thirty pregnant Sprague Dawley (SD) rats were randomly divided into exposed and control groups. At PND56, the number of sperm, luteinizing hormone, and testosterone in the BPA-exposed group decreased, and testicular tissue structure was damaged in offsprings. At GD20, the miRNA profile in the testis of male offspring was examined and the expression levels of 28 deregulated miRNAs were validated by qRT-PCR. We found that miR-361-5p, miR-203a-3p, and miR-19b-2-5p had significantly different expression levels in the testis. These results suggest that maternal exposure to BPA can lead to differential changes in progeny miRNAs, which will provide direction for future in-depth mechanisms of reproductive injury.

Endocrine disruption of gene expression and microRNA profiles in hippocampus and hypothalamus of California mice: Association of gene expression changes with behavioural outcomes

The hypothalamus and hippocampus are sensitive to early exposure to endocrine disrupting chemicals (EDCs). Two EDCs that have raised particular concerns are bisphenol A (BPA), a widely prevalent chemical in many common household items, and genistein (GEN), a phyto-oestrogen present in soy and other plants. We hypothesised that early exposure to BPA or GEN may lead to permanent effects on gene expression profiles for both coding RNAs (mRNAs) and microRNAs (miRs), which can affect the translation of mRNAs. Such EDC-induced biomolecular changes may affect behavioural and metabolic patterns. California mice (Peromyscus californicus) male and female offspring were developmentally exposed via the maternal diet to BPA (5 mg kg^-1 feed weight low dose [LD] and 50 mg kg^-1 feed weight upper dose [UD]), GEN (250 mg kg^-1 feed weight) or a phyto-oestrogen-free diet (AIN) control. Behavioural and metabolic tests were performed at 180 days of age. A quantitative polymerase chain reacttion analysis was performed for candidate mRNAs and miRs in the hypothalamus and hippocampus. LD BPA and GEN exposed California mice offspring showed socio-communication impairments. Hypothalamic Avp, Esr1, Kiss1 and Lepr were increased in LD BPA offspring. miR-153 was elevated but miR-181a was reduced in LD BPA offspring. miR-9 and miR-153 were increased in the hippocampi of LD BPA offspring, whereas GEN decreased hippocampal miR-7a and miR-153 expression. Correlation analyses revealed neural expression of miR-153 and miR-181a was associated with socio-communication deficits in LD BPA individuals. The findings reveal a cause for concern such that developmental exposure of BPA or GEN in California mice (and potentially by translation in humans) can lead to long standing neurobehavioural consequences.

Neuro-toxic and Reproductive Effects of BPA

Background:

Bisphenol A (BPA) is one of the highest volume chemicals produced worldwide. It has recognized activity as an endocrine-disrupting chemical and has suspected roles as a neurological and reproductive toxicant. It interferes in steroid signaling, induces oxidative stress, and affects gene expression epigenetically. Gestational, perinatal and neonatal exposures to BPA affect developmental processes, including brain development and gametogenesis, with consequences on brain functions, behavior, and fertility.

Methods:

This review critically analyzes recent findings on the neuro-toxic and reproductive effects of BPA (and its ana-logues), with focus on neuronal differentiation, synaptic plasticity, glia and microglia activity, cognitive functions, and the central and local control of reproduction.

Results:

BPA has potential human health hazard associated with gestational, peri- and neonatal exposure. Beginning with BPA’s disposition, this review summarizes recent findings on the neurotoxicity of BPA and its analogues, on neuronal dif-ferentiation, synaptic plasticity, neuro-inflammation, neuro-degeneration, and impairment of cognitive abilities. Furthermore, it reports the recent findings on the activity of BPA along the HPG axis, effects on the hypothalamic Gonadotropin Releas-ing Hormone (GnRH), and the associated effects on reproduction in both sexes and successful pregnancy.

Conclusion:

BPA and its analogues impair neuronal activity, HPG axis function, reproduction, and fertility. Contrasting re-sults have emerged in animal models and human. Thus, further studies are needed to better define their safety levels. This re-view offers new insights on these issues with the aim to find the “fil rouge”, if any, that characterize BPA’s mechanism of action with outcomes on neuronal function and reproduction.

The role of miRNAs in regulating adrenal and gonadal steroidogenesis

miRNAs are endogenous noncoding single-stranded small RNAs of ~22 nucleotides in length that post-transcriptionally repress the expression of their various target genes. They contribute to the regulation of a variety of physiologic processes including embryonic development, differentiation and proliferation, apoptosis, metabolism, hemostasis and inflammation. In addition, aberrant miRNA expression is implicated in the pathogenesis of numerous diseases including cancer, hepatitis, cardiovascular diseases and metabolic diseases. Steroid hormones regulate virtually every aspect of metabolism, and acute and chronic steroid hormone biosynthesis is primarily regulated by tissue-specific trophic hormones involving transcriptional and translational events. In addition, it is becoming increasingly clear that steroidogenic pathways are also subject to post-transcriptional and post-translational regulations including processes such as phosphorylation/dephosphorylation, protein‒protein interactions and regulation by specific miRNAs, although the latter is in its infancy state. Here, we summarize the recent advances in miRNA-mediated regulation of steroidogenesis with emphasis on adrenal and gonadal steroidogenesis.

Effects of Bisphenols on Testicular Steroidogenesis

Over the last decades, the adverse effects of human exposure to the so-called "endocrine disruptors" have been a matter of scientific debate and public attention. Bisphenols are synthetic chemicals, widely used in the manufacture of hard plastic products. Bisphenol A (BPA) is one of the best-known environmental toxicants proven to alter the reproductive function in men and to cause other health problems. Consumer concern resulted in "BPA free" products and in the development of bisphenol analogs (BPA-A) to replace BPA in many applications. However, these other bisphenol derivatives seem to have effects similar to those of BPA. Although a number of reviews have summarized the effects of BPA on human reproduction, the purpose of this article is to review the effects of bisphenols on testicular steroidogenesis and to explore their mechanisms of action. Testicular steroidogenesis is a fine-regulated process, and its main product, testosterone (T), has a crucial role in fetal development and maturation and in adulthood for the maintenance of secondary sexual function and spermatogenesis. Contradictory outcomes of both human and animal studies on the effects of BPA on steroid hormone levels may be related to various factors that include study design, dosage of BPA used in in vitro studies, timing and route of exposure, and other confounding factors. We described the main possible molecular target of bisphenols on this complex pathway. We report that Leydig cells (LCs), the steroidogenic testicular component, are highly sensitive to BPA and several mechanisms concur to the functional impairment of these cells.

Global and region-specific post-transcriptional and post-translational modifications of bisphenol A in human prostate cancer cells

Bisphenol A (BPA), as synthetic monomer used in the production of polycarbonate plastic and epoxy resins, has endocrine disruptor properties and high risk on human health. Epigenetic alterations could act an important role in BPA-induced toxicity, but its mechanism has not been fully understood. We investigated the effects of BPA on gene expression of chromatin modifying enzymes, promoter methylation of tumor suppressor genes and histone modifications in human prostate carcinoma cells (PC-3). IC₅₀ value of BPA was determined as 217 and 190 μM in PC-3 cells by MTT and NRU tests, respectively. We revealed an increase in global levels of 5-methylcytocine and 5-hydroxymethylcytocine at 10 μM of BPA for 96 h. We observed a significant increase on promoter DNA methylation and decrease on gene expression of p16 gene while no change was observed for Cyclin D2 and Rassf1. Significant changes were observed in global histone modifications (H3K9ac, H3K9me3, H3K27me3, and H4K20me3) in PC-3 cells. According to these results, we investigated wide-range epigenetic modifications using PCR arrays. After 96 h BPA exposure, chromatin modifying enzymes including KDM5B and NSD1 were significantly downregulated. Also, promoter methylation of tumor suppressor genes including BCR, GSTP1, LOX, MGMT, NEUROG1, PDLIM4, PTGS2, PYCARD, TIMP3, TSC2 and ZMYDN10 altered significantly. ChIP results showed that H3K9ac, H3K9me3 and H3K27me3 modifications on p16 gene showed significant increases after 1 and 10 μM of BPA exposure. In conclusion, epigenetic signatures such as DNA methylation and histone modifications could be proposed as molecular biomarkers of BPA-induced prostate cancer progression.

Competitive endogenous RNA (ceRNA) regulation network of lncRNA-miRNA-mRNA during the process of the nickel-induced steroidogenesis disturbance in rat Leydig cells

Nickel (Ni) is a ubiquitous environmental pollutant, which can disrupt the production of steroid in rat Leydig cells. Steroidogenesis can be affected by non-coding RNAs (ncRNAs), which operate in normal physiological processes. To date, however, very few studies have focused on whether ncRNAs are involved in Ni-induced steroidogenesis disturbance. The present study was designed to investigate the impact of NiSO₄ on the regulation of RNA networks including long non-coding RNA (lncRNA), microRNA (miRNA), and mRNA in rat Leydig cells. After treatment with 1000 μmol/L NiSO₄ for 24 h, 372 lncRNAs, 27 miRNAs (fold change>2, p < .05) and 3666 mRNAs (fold change>2, p < .01, and FDR < 0.01) were identified to be markedly altered by high-throughput sequencing analysis in rat Leydig cells. Functional analysis showed that the differentially expressed mRNAs were annotated into some steroid-related pathways. A dysregulated competing endogenous RNA (ceRNA) network of lncRNA-miRNA-mRNA was constructed based on bioinformatic analysis. Furthermore, a ceRNA network related to steroidogenesis was selected to analyze further and after the validation by qRT-PCR. The LOC102549726/miR-760-3p/Atf6, LOC102549726/miR-760-3p/Ets1, LOC102549726/miR-760-3p/Sik1 and AABR07037489.1/miR-708-5p/MAPK14 ceRNA networks were eventually confirmed. Collectively, our study provided a systematic perspective on the potential role of ncRNAs in steroidogenesis disturbance induced by Ni in rat Leydig cells.

Do G-protein coupled estrogen receptor and bisphenol A analogs influence on Leydig cell epigenetic regulation in immature boar testis ex vivo?

Organotypic culture of testicular fragments from 7-day-old male pigs (Polish White Large) was used. Tissues were treated with an antagonist of G-protein coupled estrogen receptor (GPER) (G-15; 10 nM), and bisphenol A (BPA), and its analogs (TBBPA, TCBPA; 10 nM) alone or in combination and analyzed using electron and light (stainings for collagen fibers, lipid droplet and autophagy markers) microscopes. In addition, mRNA and protein abundances and localization of molecules required for miRNA biogenesis and function (Drosha, Exportin 5; EXPO5, Dicer, and Argonaute 2; AGO2) were assessed together with calcium ion (Ca²⁺) and estradiol concentrations. Regardless of GPER blockade and/or treatment with BPA, TBBPA and TCBPA, there were no changes in Leydig cell morphology. Also, there were no changes in lipid droplet content and distribution but there were changes in lipid and autophagy protein abundance. In the interstitial tissue, there was an increase of collagen content, especially after treatment with BPA analogs and G-15 + BPA. Independent of the treatment, there was downregulation of EXPO5 and Dicer genes but the Drosha and AGO2 genes were markedly upregulated as a result of treatment with G-15 + BPA and TCBPA, respectively. There was always a lesser abundance of EXPO5 and AGO2 proteins regardless of treatment. There was markedly greater abundances of Drosha after G-15 + BPA treatment, and this also occurred for Dicer after treatment with G-15 + TCBPA. Immunolocalization of miRNA proteins indicated there was a cytoplasmic-nuclear pattern in control and treated cells. There was an increase of Ca²⁺ concentrations after treatment with G-15 and BPA analogs. Estradiol secretion decreased after antagonist and chemical treatments when these were administered alone, however, there was an increase in estradiol secretion after treatment with combinations of these compounds.

Replacement Bisphenols Adversely Affect Mouse Gametogenesis with Consequences for Subsequent Generations

20 years ago, accidental bisphenol A (BPA) exposure caused a sudden increase in chromosomally abnormal eggs from our control mice [1]. Subsequent rodent studies demonstrated developmental effects of exposure with repercussions on adult health and fertility (e.g., [2-9]; reviewed in [10-17]). Studies in monkeys, humans, fish, and worms suggest BPA effects extend across species (e.g., [18-30]; reviewed in [31-33]). Widespread use has resulted in ubiquitous environmental contamination and human BPA exposure. Consumer concern resulted in "BPA-free" products produced using structurally similar bisphenols that are now detectable environmental and human contaminants (e.g., [34-41]). We report here studies initiated by meiotic changes mirroring our previous BPA experience and implicating exposure to BPS (a common BPA replacement) from damaged polysulfone cages. Like with BPA [1, 2, 5], our data show that exposure to common replacement bisphenols induces germline effects in both sexes that may affect multiple generations. These findings add to growing evidence of the biological risks posed by this class of chemicals. Rapid production of structural variants of BPA and other EDCs circumvents efforts to eliminate dangerous chemicals, exacerbates the regulatory burden of safety assessment, and increases environmental contamination. Our experience suggests that these environmental contaminants pose a risk not only to reproductive health but also to the integrity of the research environment. EDCs, like endogenous hormones, can affect diverse processes. The sensitivity of the germline allows us to detect effects that, although not immediately apparent in other systems, may induce variability that undermines experimental reproducibility and impedes scientific advancement.