Birth defects in children of men exposed in utero to diethylstilbestrol (DES)

Genome-wide methylation analysis in patients with proximal hypospadias - a pilot study and review of the literature

In patients with proximal hypospadias, often no genetic cause is identified despite extensive genetic testing. Many genes involved in sex development encode transcription factors with strict timing and dosing of the gene products. We hypothesised that there might be recurrent differences in DNA methylation in boys with hypospadias and that these might differ between patients born small versus appropriate for gestational age. Genome-wide Methylated DNA sequencing (MeD-seq) was performed on 32bp LpnPI restriction enzyme fragments after RE-digestion in leucocytes from 16 XY boys with unexplained proximal hypospadias, one with an unexplained XX testicular disorder/difference of sex development (DSD) and twelve, healthy, sex- and age-matched controls. Five of seven differentially methylated regions (DMRs) between patients and XY controls were in the Long Intergenic Non-Protein Coding RNA 665 (LINC00665; CpG24525). Three patients showed hypermethylation of MAP3K1. Finally, no DMRs in XX testicular DSD associated genes were identified in the XX boy versus XX controls. In conclusion, we observed no recognizable epigenetic signature in 16 boys with XY proximal hypospadias and no difference between children born small versus appropriate for gestational age. Comparison to previous methylation studies in individuals with hypospadias did not show consistent findings, possibly due to the use of different inclusion criteria, tissues and methods.

Pressures of the urban environment on the endocrine system: Adverse effects and adaptation

With an increasing collective awareness of the rapid environmental changes, questions and theories regarding the adaptability of organisms are emerging. Global warming as well as chemical and non-chemical pollution have been identified as triggers of these adaptative changes, but can we link different kinds of stressors to certain phenotypic traits? The physiological adaptation, and particularly endocrine system adaptation, of living beings to urban environments is a fascinating way of studying urban endocrinology, which has emerged as a research field in 2007. In this paper, we stress how endocrine disruption in humans and environment can be studied in the urban environment by measuring the levels of pollution, endocrine activities or adversity. We broaden the focus to include not only exposure to the chemicals that have invaded our private spheres and their effects on wild and domestic species but also non-chemical effectors such as light, noise and climate change. We argue that taking into account the various urban stress factors and their effects on the endocrine system would enable the adoption of new approaches to protect living organisms.

The adverse role of endocrine disrupting chemicals in the reproductive system

Reproductive system diseases pose prominent threats to human physical and mental well-being. Besides being influenced by genetic material regulation and changes in lifestyle, the occurrence of these diseases is closely connected to exposure to harmful substances in the environment. Endocrine disrupting chemicals (EDCs), characterized by hormone-like effects, have a wide range of influences on the reproductive system. EDCs are ubiquitous in the natural environment and are present in a wide range of industrial and everyday products. Currently, thousands of chemicals have been reported to exhibit endocrine effects, and this number is likely to increase as the testing for potential EDCs has not been consistently required, and obtaining data has been limited, partly due to the long latency of many diseases. The ability to avoid exposure to EDCs, especially those of artificially synthesized origin, is increasingly challenging. While EDCs can be divided into persistent and non-persistent depending on their degree of degradation, due to the recent uptick in research studies in this area, we have chosen to focus on the research pertaining to the detrimental effects on reproductive health of exposure to several EDCs that are widely encountered in daily life over the past six years, specifically bisphenol A (BPA), phthalates (PAEs), polychlorinated biphenyls (PCBs), parabens, pesticides, heavy metals, and so on. By focusing on the impact of EDCs on the hypothalamic-pituitary-gonadal (HPG) axis, which leads to the occurrence and development of reproductive system diseases, this review aims to provide new insights into the molecular mechanisms of EDCs' damage to human health and to encourage further in-depth research to clarify the potentially harmful effects of EDC exposure through various other mechanisms. Ultimately, it offers a scientific basis to enhance EDCs risk management, an endeavor of significant scientific and societal importance for safeguarding reproductive health.

Role of epigenetics in the etiology of hypospadias through penile foreskin DNA methylation alterations

Abnormal penile foreskin development in hypospadias is the most frequent genital malformation in male children, which has increased dramatically in recent decades. A number of environmental factors have been shown to be associated with hypospadias development. The current study investigated the role of epigenetics in the etiology of hypospadias and compared mild (distal), moderate (mid shaft), and severe (proximal) hypospadias. Penile foreskin samples were collected from hypospadias and non-hypospadias individuals to identify alterations in DNA methylation associated with hypospadias. Dramatic numbers of differential DNA methylation regions (DMRs) were observed in the mild hypospadias, with reduced numbers in moderate and low numbers in severe hypospadias. Atresia (cell loss) of the principal foreskin fibroblast is suspected to be a component of the disease etiology. A genome-wide (> 95%) epigenetic analysis was used and the genomic features of the DMRs identified. The DMR associated genes identified a number of novel hypospadias associated genes and pathways, as well as genes and networks known to be involved in hypospadias etiology. Observations demonstrate altered DNA methylation sites in penile foreskin is a component of hypospadias etiology. In addition, a potential role of environmental epigenetics and epigenetic inheritance in hypospadias disease etiology is suggested.

Integrated Genomic and Bioinformatics Approaches to Identify Molecular Links between Endocrine Disruptors and Adverse Outcomes

Exposure to Endocrine Disrupting Chemicals (EDC) has been linked with several adverse outcomes. In this review, we examine EDCs that are pervasive in the environment and are of concern in the context of human, animal, and environmental health. We explore the consequences of EDC exposure on aquatic life, terrestrial animals, and humans. We focus on the exploitation of genomics technologies and in particular whole transcriptome sequencing. Genome-wide analyses using RNAseq provides snap shots of cellular, tissue and whole organism transcriptomes under normal physiological and EDC perturbed conditions. A global view of gene expression provides highly valuable information as it uncovers gene families or more specifically, pathways that are affected by EDC exposures, but also reveals those that are unaffected. Hypotheses about genes with unknown functions can also be formed by comparison of their expression levels with genes of known function. Risk assessment strategies leveraging genomic technologies and the development of toxicology databases are explored. Finally, we review how the Adverse Outcome Pathway (AOP) has exploited this high throughput data to provide a framework for toxicology studies.

Are the Effects of DES Over? A Tragic Lesson from the Past

Diethylstilbestrol (DES), a transplacental endocrine-disrupting chemical, was prescribed to pregnant women for several decades. The number of women who took DES is hard to know precisely, but it has been estimated that over 10 million people have been exposed around the world. DES was classified in the year 2000 as carcinogenic to humans. The deleterious effects induced by DES are very extensive, such as abnormalities or cancers of the genital tract and breast, neurodevelopmental alterations, problems associated with socio-sexual behavior, and immune, pancreatic and cardiovascular disorders. Not only pregnant women but also their children and grandchildren have been affected. Epigenetic alterations have been detected, and intergenerational effects have been observed. More cohort follow-up studies are needed to establish if DES effects are transgenerational. Even though DES is not currently in use, its effects are still present, and families previously exposed and their later generations deserve the continuity of the research studies.

Evidence of intergenerational transmission of Diethylstilbestrol (DES) health effects: Hindsight and insight

This review summarizes key findings from the US National Cancer Institute (NCI) DES Combined Cohort Study with a focus on the results of the NCI Third Generation Study, a cohort of DES-exposed and unexposed granddaughters. Findings to date from the Third Generation Study are discussed in the context of other research efforts and case reports suggesting an intergenerational heritability of DES-related effects. The DES story serves as a model for the influence of endocrine disrupting chemicals on human health. It also serves as a warning of the special hazards of pregnancy exposures, and more broadly, of the potential for invisible health consequences arising from new or changing exposures.

Praegnatio Perturbatio-Impact of Endocrine-Disrupting Chemicals

The burden of adverse pregnancy outcomes such as preterm birth and low birth weight is considerable across the world. Several risk factors for adverse pregnancy outcomes have been identified. One risk factor for adverse pregnancy outcomes receiving considerable attention in recent years is gestational exposure to endocrine-disrupting chemicals (EDCs). Humans are exposed to a multitude of environmental chemicals with known endocrine-disrupting properties, and evidence suggests exposure to these EDCs have the potential to disrupt the maternal-fetal environment culminating in adverse pregnancy and birth outcomes. This review addresses the impact of maternal and fetal exposure to environmental EDCs of natural and man-made chemicals in disrupting the maternal-fetal milieu in human leading to adverse pregnancy and birth outcomes-a risk factor for adult-onset noncommunicable diseases, the role lifestyle and environmental factors play in mitigating or amplifying the effects of EDCs, the underlying mechanisms and mediators involved, and the research directions on which to focus future investigations to help alleviate the adverse effects of EDC exposure.

Endocrine disrupting chemicals in the pathogenesis of hypospadias; developmental and toxicological perspectives

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Penis development is regulated by a tight balance of androgens and estrogens.

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EDCs that impact androgen/estrogen balance during development cause hypospadias.

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Cross-disciplinary collaborations are needed to define a mechanistic link.

Hypospadias is a defect in penile urethral closure that occurs in approximately 1/150 live male births in developed nations, making it one of the most common congenital abnormalities worldwide. Alarmingly, the frequency of hypospadias has increased rapidly over recent decades and is continuing to rise. Recent research reviewed herein suggests that the rise in hypospadias rates can be directly linked to our increasing exposure to endocrine disrupting chemicals (EDCs), especially those that affect estrogen and androgen signalling. Understanding the mechanistic links between endocrine disruptors and hypospadias requires toxicologists and developmental biologists to define exposures and biological impacts on penis development. In this review we examine recent insights from toxicological, developmental and epidemiological studies on the hormonal control of normal penis development and describe the rationale and evidence for EDC exposures that impact these pathways to cause hypospadias. Continued collaboration across these fields is imperative to understand the full impact of endocrine disrupting chemicals on the increasing rates of hypospadias.

New frontiers of developmental endocrinology opened by researchers connecting irreversible effects of sex hormones on developing organs

In the early 1960's, at Professor Bern's laboratory, University of California, Berkeley) in the US, Takasugi discovered ovary-independent, persistent vaginal changes in mice exposed neonatally to estrogen, which resulted in vaginal cancer later in life. Reproductive abnormalities in rodents were reported as a result of perinatal exposure to various estrogenic chemicals. Ten years later, vaginal cancers were reported in young women exposed in utero to the synthetic estrogen diethylstilbestrol (DES) and this has been called the "DES syndrome". The developing organism is particularly sensitive to developmental exposure to estrogens inducing long-term changes in various organs including the reproductive organs. The molecular mechanism underlying the persistent vaginal changes induced by perinatal estrogen exposure was partly demonstrated. Persistent phosphorylation and sustained expression of EGF-like growth factors, lead to estrogen receptor α (ESR1) activation, and then persistent vaginal epithelial cell proliferation. Agents which are weakly estrogenic by postnatal criteria may have major developmental effects, especially during a critical perinatal period. The present review outlines various studies conducted by four generations of investigators all under the influence of Prof. Bern. The studies include reports of persistent changes induced by neonatal androgen exposure, analyses of estrogen responsive genes, factors determining epithelial differentiation in the Müllerian duct, ESR and growth factor signaling, and polyovular follicles in mammals. This review is then expanded to the studies on the effects of environmental estrogens on wildlife and endocrine disruption in Daphnids.

Regulation of axial and head patterning during planarian regeneration by a commensal bacterium

Some animals, such as planaria, can regenerate complex anatomical structures in a process regulated by genetic and biophysical factors, but additional external inputs into regeneration remain to be uncovered. Microbial communities inhabiting metazoan organisms are important for metabolic, immune, and disease processes, but their instructive influence over host structures remains largely unexplored. Here, we show that Aquitalea sp. FJL05, an endogenous commensal bacterium of Dugesia japonica planarians, and one of the small molecules it produces, indole, can influence axial and head patterning during regeneration, leading to regeneration of permanently two-headed animals. Testing the impact of indole on planaria tissues via RNA sequencing, we find that indole alters the regenerative outcomes in planarians through changes in expression to patterning genes, including a downregulation of Wnt pathway genes. These data provide a unique example of the product of a commensal bacterium modulating transcription of patterning genes to affect the host's anatomical structure during regeneration.

Mini-review: Epigenetic mechanisms that promote transgenerational actions of endocrine disrupting chemicals: Applications to behavioral neuroendocrinology

It is our hope this mini-review will stimulate discussion and new research. Here we briefly examine the literature on transgenerational actions of endocrine disrupting chemicals (EDCs) on brain and behavior and their underlying epigenetic mechanisms including: DNA methylation, histone modifications, and non-coding RNAs. We stress that epigenetic modifications need to be examined in a synergistic manner, as they act together in situ on chromatin to change transcription. Next we highlight recent work from one of our laboratories (VGC). The data provide new evidence that the sperm genome is poised for transcription. In developing sperm, gene enhancers and promoters are accessible for transcription and these activating motifs are also found in preimplantation embryos. Thus, DNA modifications associated with transcription factors during fertilization, in primordial germ cells (PGCs), and/or during germ cell maturation may be passed to offspring. We discuss the implications of this model to EDC exposures and speculate on whether natural variation in hormone levels during fertilization and PGC migration may impart transgenerational effects on brain and behavior. Lastly we discuss how this mechanism could apply to neural sexual differentiation.

Genital tract and reproductive characteristics in daughters of women and men prenatally exposed to diethylstilbestrol (DES)

OBJECTIVE

Prenatal exposure of women to diethylstilbestrol (DES) has been associated with reproductive tract anomalies, menstrual irregularity, infertility and pregnancy complications. In prenatally exposed men, adverse effects included genital anomalies and possible risk of infertility. In children of prenatally exposed women, i.e the third generation, an increased incidence of genital defects was observed in sons (hypospadias), but not in daughters. In daughters of prenatally exposed men, the incidence of genital anomalies was in the normal range. Experimental studies in mice evidenced an increased incidence of reproductive tract anomalies in the female descendants of females and males prenatally exposed to DES, indicative of transgenerational transmission of DES defects. The aim of this study is to assess genital tract defects, fertility and pregnancy outcome, in daughters of women and men prenatally exposed to DES.

METHODS

In a retrospective observational analysis, 759 daughters of prenatally exposed women and men reported their genital and reproductive characteristics that were compared with those of: 1) general population in France; 2) two cohorts of daughters of exposed women reported in previous publications; 3) women prenatally exposed to DES.

RESULTS

An increased incidence of uterine defects was observed, with both doubling of uterus and bicornuate and aplastic uterus which constitutes the Mayer-Rokitansky-Küster-Hauser syndrome (MRKHS). No specific anomalies described in prenatally exposed women such as T-shape or hypoplastic uterus were reported. Infertility appeared to be in the normal range. Pregnancy outcomes of our 121 pregnancies of women born to DES exposed mothers and two other published cohorts presented inconsistent results for ectopic pregnancy, miscarriage and preterm delivery. Early and late miscarriages were higher than expected in general population in our cohort but not in the two others.

CONCLUSION

These results must be considered as preliminary, due to the small numbers of patients, limited follow-up duration after birth due to young age of the studied population, and observational methods. An important point is that the high risk of reproductive dysfunction of women prenatally exposed to DES was not observed in their daughters. There is a signal on the high incidence of uterine defects, especially aplastic uterus, and its possible link with DES exposure through epigenetic effects is discussed in our findings. Inconsistent findings regarding pregnancy outcomes in the third generation are worthy of further examination.

Microtia epigenetics: An overview of review and new viewpoint

INTRODUCTION

Microtia is a congenital malformation of the external and middle ear caused by the abnormal development of the first and second zygomatic arch and the first sulcus. There is currently no consensus concerning the pathogenesis and etiology of microtia; genetic and environmental factors may play a role. Gene-based studies have focused on finding the genes that cause microtia and on gene function defects. However, no clear pathogenic genes have so far been identified. Microtia is multifactorial; gene function defects cannot completely explain its pathogenesis. In recent years, the epigenetic aspects of microtia have begun to receive attention.

CONCLUSIONS

Analysis of the existing data suggests that certain key genes and pathways may be the underlying cause of congenital microtia. However, further exploration is needed.

Endocrine disruption through membrane estrogen receptors and novel pathways leading to rapid toxicological and epigenetic effects

Estrogen binding to estrogen receptors (ESR) triggers signaling cascades within cells. Historically, a major emphasis has been characterizing estrogen-induced genomic actions resulting from binding to nuclear estrogen receptor 1 (nESR1). However, recent evidence indicates the first receptors estrogens encounter as they enter a cell, membrane ESR1 (mESR1), also play crucial roles. Membrane and nuclear ESR are derived from the same transcripts but the former are directed to the membrane via palmitoylation. Binding and activation of mESR1 leads to rapid fluctuations in cAMP and Ca+2 and stimulation of protein kinase pathways. Endocrine disrupting chemicals (EDC) that mimic 17β-estradiol can signal through mESR1 and elicit non-genomic effects. Most current EDC studies have focused on genomic actions via nESR1. However, increasing number of studies have begun to examine potential EDC effects mediated through mESR1, and some EDC might have higher potency for signaling through mESR1 than nESR1. The notion that such chemicals might also affect mESR1 signaling via palmitoylation and depalmitoylation pathways has also begun to gain currency. Recent development of transgenic mice that lack either mESR1 or nESR1, while retaining functional ESR1 in the other compartment, will allow more precise in vivo approaches to determine EDC effects through nESR1 and/or mESR1. It is increasingly becoming apparent in this quickly evolving field that EDC directly affect mESR and estrogen signaling, but such chemicals can also affect proportion of ESR reaching the membrane. Future EDC studies should be designed to consider the full range of effects through mESR alone and in combination with nESR.