scholarly journals Environmental exposures, fetal testis development and function: phthalates and beyond

Reproduction ◽  
2021 ◽  
Author(s):  
Hui Li ◽  
Daniel J. Spade
Keyword(s):  
Germ Cell ◽  
Germ Cells ◽  
Molecular Mechanisms ◽  
Cell Function ◽  
Current Knowledge ◽  
Environmental Chemicals ◽  
Environmental Toxicants ◽  
Cell Contacts ◽  
Testis Development ◽  
Fetal Testis

Fetal development of the mammalian testis relies on a series of interrelated cellular processes: commitment of somatic progenitor cells to Sertoli and Leydig cell fate, migration of endothelial cells and Sertoli cells, differentiation of germ cells, deposition of basement membrane, and establishment of cell-cell contacts, including Sertoli-Sertoli and Sertoli-germ cell contacts. These processes are orchestrated by intracellular, endocrine, and paracrine signaling processes. Because of this complexity, testis development can be disrupted by a variety of environmental toxicants. Toxicity of phthalic acid esters (phthalates) to the fetal testis has been the subject of extensive research for two decades, and phthalates have become an archetypal fetal testis toxicant. Phthalates disrupt the seminiferous cord formation and maturation, Sertoli cell function, biosynthesis of testosterone in Leydig cells, and impair germ cell survival and development, producing characteristic multinucleated germ cells. However, the mechanisms responsible for these effects are not fully understood. This review describes current knowledge of the adverse effects of phthalates on the fetal testis and their associated windows of sensitivity, and compares and contrasts the mechanisms by which toxicants of current interest, bisphenol A and its replacements, analgesics, and perfluorinated alkyl substances, alter testicular developmental processes. Working towards a better understanding of the molecular mechanisms responsible for phthalate toxicity will be critical for understanding the long-term impacts of environmental chemicals and pharmaceuticals on human reproductive health.

scholarly journals Role of Nodal signalling in testis development and initiation of testicular cancer

Reproduction ◽  
2019 ◽  
Vol 158 (2) ◽  
pp. R67-R77 ◽  
Author(s):  
Katrine Harpelunde Poulsen ◽  
Anne Jørgensen
Keyword(s):  
Testicular Cancer ◽  
Germ Cell ◽  
Sertoli Cell ◽  
Cell Function ◽  
Testicular Development ◽  
Fetal Life ◽  
Cell Specification ◽  
Testis Development ◽  
Fetal Testis ◽  
Cancer Pathogenesis

Testicular development from the initially bipotential gonad is a tightly regulated process involving a complex signalling cascade to ensure proper sequential expression of signalling factors and secretion of steroid hormones. Initially, Sertoli cell specification facilitates differentiation of the steroidogenic fetal Leydig cells and establishment of the somatic niche, which is critical in supporting the germ cell population. Impairment of the somatic niche during fetal life may lead to development of male reproductive disorders, including arrest of gonocyte differentiation, which is considered the first step in the testicular cancer pathogenesis. In this review, we will outline the signalling pathways involved in fetal testis development focusing on the Nodal pathway, which has recently been implicated in several aspects of testicular differentiation in both mouse and human studies. Nodal signalling plays important roles in germ cell development, including regulation of pluripotency factor expression, proliferation and survival. Moreover, the Nodal pathway is involved in establishment of the somatic niche, including formation of seminiferous cords, steroidogenesis and Sertoli cell function. In our outline of fetal testis development, important differences between human and mouse models will be highlighted to emphasise that information obtained from mouse studies cannot always be directly translated to humans. Finally, the implications of dysregulated Nodal signalling in development of the testicular cancer precursor, germ cell neoplasia in situ, and testicular dysgenesis will be discussed – none of which arise in rodents, emphasising the importance of human models in the effort to increase our understanding of origin and early development of these disorders.

Regulation of meiotic entry and gonadal sex differentiation in the human: normal and disrupted signaling

2014 ◽  
Vol 5 (4) ◽  
pp. 331-341 ◽  
Author(s):  
Anne Jørgensen ◽  
Ewa Rajpert-De Meyts
Keyword(s):  
Germ Cell ◽  
Germ Cells ◽  
Fetal Development ◽  
Molecular Mechanisms ◽  
Current Knowledge ◽  
Sex Differentiation ◽  
Cell Cancer ◽  
Testicular Germ Cell ◽  
Unique Type ◽  
Germ Cell Differentiation

AbstractMeiosis is a unique type of cell division that is performed only by germ cells to form haploid gametes. The switch from mitosis to meiosis exhibits a distinct sex-specific difference in timing, with female germ cells entering meiosis during fetal development and male germ cells at puberty when spermatogenesis is initiated. During early fetal development, bipotential primordial germ cells migrate to the forming gonad where they remain sexually indifferent until the sex-specific differentiation of germ cells is initiated by cues from the somatic cells. This irreversible step in gonadal sex differentiation involves the initiation of meiosis in fetal ovaries and prevention of meiosis in the germ cells of fetal testes. During the last decade, major advances in the understanding of meiosis regulation have been accomplished, with the discovery of retinoic acid as an inducer of meiosis being the most prominent finding. Knowledge about the molecular mechanisms regulating meiosis signaling has mainly been established by studies in rodents, while this has not yet been extensively investigated in humans. In this review, the current knowledge about the regulation of meiosis signaling is summarized and placed in the context of fetal gonad development and germ cell differentiation, with emphasis on results obtained in humans. Furthermore, the consequences of dysregulated meiosis signaling in humans are briefly discussed in the context of selected pathologies, including testicular germ cell cancer and some forms of male infertility.

scholarly journals Phase Transitioned Nuclear Oskar Promotes Cell Division of Drosophila Primordial Germ Cells

2018 ◽  
Author(s):  
Kathryn E. Kistler ◽  
Tatjana Trcek ◽  
Thomas R. Hurd ◽  
Ruoyu Chen ◽  
Feng-Xia Liang ◽  
...  
Keyword(s):  
Germ Cell ◽  
Cell Fate ◽  
Germ Cells ◽  
Cell Function ◽  
Primordial Germ Cells ◽  
Nuclear Localization Sequence ◽  
Cell Systems ◽  
Germ Granules ◽  
Localization Sequence ◽  
Transcriptional Gene Regulation

ABSTRACTGerm granules are non-membranous ribonucleoprotein granules deemed the hubs for post-transcriptional gene regulation and functionally linked to germ cell fate across species. Little is known about the physical properties of germ granules and how these relate to germ cell function. Here we study two types of germ granules in the Drosophila embryo: cytoplasmic germ granules that instruct primordial germ cells (PGCs) formation and nuclear germ granules within early PGCs with unknown function. We show that cytoplasmic and nuclear germ granules are phase transitioned condensates nucleated by Oskar protein that display liquid as well as hydrogel-like properties. Focusing on nuclear granules, we find that Oskar drives their formation in heterologous cell systems. Multiple, independent Oskar protein domains synergize to promote granule phase separation. Deletion of Oskar’s nuclear localization sequence specifically ablates nuclear granules in cell systems. In the embryo, nuclear germ granules promote germ cell divisions thereby increasing PGC number for the next generation.

scholarly journals Hepatocyte growth factor modulates in vitro survival and proliferation of germ cells during postnatal testis development

2006 ◽  
Vol 189 (1) ◽  
pp. 137-146 ◽  
Author(s):  
A Catizone ◽  
G Ricci ◽  
J Del Bravo ◽  
M Galdieri
Keyword(s):  
Growth Factor ◽  
Hepatocyte Growth Factor ◽  
Germ Cell ◽  
Germ Cells ◽  
Cell Types ◽  
Tyrosine Kinase Receptor ◽  
Testis Development ◽  
Pachytene Spermatocytes ◽  
Hepatocyte Growth

The hepatocyte growth factor (HGF) is a pleiotropic cytokine that influences mitogenesis, motility and differentiation of many different cell types by its tyrosine kinase receptor c-Met. We previously demonstrated that the c-Met/HGF system is present and functionally active during postnatal testis development. We found also that spermatozoa express c-Met and that HGF has a positive effect on the maintenance of sperm motility. In the present paper, we extend our study on the germ cells at different stages of differentiation during the postnatal development of the testis. We demonstrate that c-met is present in rat spermatogonia, pachytene spermatocytes and round spermatids and that HGF significantly increases spermatogonial proliferation in 8- to 10-day-old pre-pubertal rats. At this age HGF does not affect Sertoli cells and peritubular myoid cells proliferation. In addition, we studied the effect of the factor on germ cell apoptosis and we show that HGF prevents the germ cell apoptotic process. We also studied the effect of HGF on 18- to 20-day-old and 28- to 30-day-old rat testes. At these ages also the factor significantly increases germ cell duplication and decreases the number of apoptotic cells. However, the effect on programmed cell death is higher in the 8- to 10-day-old rats and declines in the older animals. In conclusion, we report that rat germ cells (spermatogonia, pachytene spermatocytes and round spermatids) express c-met and that HGF modulates germ cell proliferating activity and apoptosis in vitro. These data indicate that the c-Met/HGF system is involved in male germ cell homeostasis and, consequently, has a role in male fertility.

scholarly journals Effects of environmental Bisphenol A exposures on germ cell development and Leydig cell function in the human fetal testis

PLoS ONE ◽  
2018 ◽  
Vol 13 (1) ◽  
pp. e0191934 ◽  
Author(s):  
Soria Eladak ◽  
Delphine Moison ◽  
Marie-Justine Guerquin ◽  
Gabriele Matilionyte ◽  
Karen Kilcoyne ◽  
...  
Keyword(s):  
Bisphenol A ◽  
Germ Cell ◽  
Leydig Cell ◽  
Cell Function ◽  
Cell Development ◽  
Germ Cell Development ◽  
Fetal Testis ◽  
Leydig Cell Function

scholarly journals The dog as a sentinel species for environmental effects on human fertility

Reproduction ◽  
2020 ◽  
Vol 159 (6) ◽  
pp. R265-R276 ◽  
Author(s):  
Rebecca Nicole Sumner ◽  
Imogen Thea Harris ◽  
Morne Van der Mescht ◽  
Andrew Byers ◽  
Gary Crane William England ◽  
...  
Keyword(s):  
Current Knowledge ◽  
Sperm Quality ◽  
Analytical Data ◽  
Real Life ◽  
Biological Tissues ◽  
Environmental Chemicals ◽  
Human Reproduction ◽  
Sentinel Species ◽  
Environmental Toxicants ◽  
Long Term Effects

Despite the vast body of evidence that environmental toxicants adversely affect reproductive development and function across species, demonstrating true cause and effect in the human remains a challenge. Human meta-analytical data, showing a temporal decline in male sperm quality, are paralleled by a single laboratory study showing a similar 26-year decline in the dog, which shares the same environment. These data are indicative of a common cause. Environmental chemicals (ECs) detected in reproductive tissues and fluids induce similar, short term, adverse effects on human and dog sperm. Both pre- and post-natal stages of early life development are sensitive to chemical exposures and such changes could potentially cause long term effects in the adult. The environmental ‘pollutome’ (mixtures of ECs) is determined by industrialisation, atmospheric deposition and bioaccumulation and characterises real-life exposure. In Arctic ecosystems, dietary and non-dietary chemical contaminants are detectable in biological tissues and linked with adverse health effects in both dogs and their handlers. In the female, such exposure could contribute to disorders such as ovarian insufficiency, dysregulated follicle development, ovarian cancer, and polycystic ovarian syndrome. In the dog, ovarian chemical concentrations are greater in the testis. In addition, preliminary studies indicate that dietary exposures may influence the sex ratio in the offspring in favour of females. Within this article, we review current knowledge on chemical effects on human reproduction and suggest that the dog, as a sentinel species for such effects, is an essential tool for addressing critical data gaps in this field.

scholarly journals Effect of environmental and pharmaceutical exposures on fetal testis development and function: a systematic review of human experimental data

2019 ◽  
Vol 25 (4) ◽  
pp. 397-421 ◽  
Author(s):  
Karen R Kilcoyne ◽  
Rod T Mitchell
Keyword(s):  
Systematic Review ◽  
Meta Analysis ◽  
Experimental Studies ◽  
Epidemiological Studies ◽  
Environmental Chemicals ◽  
Testicular Development ◽  
Human Tissues ◽  
Testis Development ◽  
Fetal Testis ◽  
And Function

Abstract BACKGROUND Overall, the incidence of male reproductive disorders has increased in recent decades. Testicular development during fetal life is crucial for subsequent male reproductive function. Non-genomic factors such as environmental chemicals, pharmaceuticals and lifestyle have been proposed to impact on human fetal testicular development resulting in subsequent effects on male reproductive health. Whilst experimental studies using animal models have provided support for this hypothesis, more recently a number of experimental studies using human tissues and cells have begun to translate these findings to determine direct human relevance. OBJECTIVE AND RATIONALE The objective of this systematic review was to provide a comprehensive description of the evidence for effects of prenatal exposure(s) on human fetal testis development and function. We present the effects of environmental, pharmaceutical and lifestyle factors in experimental systems involving exposure of human fetal testis tissues and cells. Comparison is made with existing epidemiological data primarily derived from a recent meta-analysis. SEARCH METHODS For identification of experimental studies, PubMed and EMBASE were searched for articles published in English between 01/01/1966 and 13/07/2018 using search terms including ‘endocrine disruptor’, ‘human’, ‘fetal’, ‘testis’, ‘germ cells’, ‘testosterone’ and related search terms. Abstracts were screened for selection of full-text articles for further interrogation. Epidemiological studies involving exposure to the same agents were extracted from a recent systematic review and meta-analysis. Additional studies were identified through screening of bibliographies of full-texts of articles identified through the initial searches. OUTCOMES A total of 25 experimental studies and 44 epidemiological studies were included. Consistent effects of analgesic and phthalate exposure on human fetal germ cell development are demonstrated in experimental models, correlating with evidence from epidemiological studies and animal models. Furthermore, analgesic-induced reduction in fetal testosterone production, which predisposes to the development of male reproductive disorders, has been reported in studies involving human tissues, which also supports data from animal and epidemiological studies. However, whilst reduced testosterone production has been demonstrated in animal studies following exposure(s) to a variety of environmental chemicals including phthalates and bisphenol A, these effects are not reproduced in experimental approaches using human fetal testis tissues. WIDER IMPLICATIONS Direct experimental evidence for effects of prenatal exposure(s) on human fetal testis development and function exists. However, for many exposures the data is limited. The increasing use of human-relevant models systems in which to determine the effects of environmental exposure(s) (including mixed exposures) on development and function of human tissues should form an important part of the process for assessment of such exposures by regulatory bodies to take account of animal–human differences in susceptibility.

scholarly journals Counteracting Environmental Chemicals with Coenzyme Q10: An Educational Primer for Use with “Antioxidant CoQ10 Restores Fertility by Rescuing Bisphenol A-Induced Oxidative DNA Damage in the Caenorhabditis elegans Germline”

Genetics ◽  
2020 ◽  
Vol 216 (4) ◽  
pp. 879-890
Author(s):  
Beatrix R. Bradford ◽  
Nicole E. Briand ◽  
Nina Fassnacht ◽  
Esabelle D. Gervasio ◽  
Aidan M. Nowakowski ◽  
...  
Keyword(s):  
Dna Damage ◽  
Caenorhabditis Elegans ◽  
Bisphenol A ◽  
Coenzyme Q10 ◽  
Oxidative Dna Damage ◽  
Molecular Mechanisms ◽  
Fluorescent Microscopy ◽  
Environmental Chemicals ◽  
Background Information ◽  
Environmental Toxicants

Environmental toxicants are chemicals that negatively affect human health. Although there are numerous ways to limit exposure, the ubiquitous nature of certain environmental toxicants makes it impossible to avoid them entirely. Consequently, scientists are continuously working toward developing strategies for combating their harmful effects. Using the nematode Caenorhabditis elegans, a model with many genetic and physiological similarities to humans, researchers in the Colaiácovo laboratory have identified several molecular mechanisms by which the toxic agent bisphenol A (BPA) interferes with reproduction. Here, we address their recent discovery that a widely available compound, Coenzyme Q10 (CoQ10), can rescue BPA-induced damage. This work is significant in that it poses a low-cost method for improving reproductive success in humans. The goal of this primer is to assist educators and students with navigating the paper entitled “Antioxidant CoQ10 Restores Fertility by Rescuing Bisphenol A-Induced Oxidative DNA Damage in the Caenorhabditis elegans Germline.” It is ideally suited for integration into an upper-level undergraduate course such as Genetics, Cell and Molecular Biology, Developmental Biology, or Toxicology. The primer provides background information on the history of BPA, the utility of the C. elegans germ line as a model for studying reproductive toxicity, and research methods including assessment of programmed cell death, fluorescent microscopy applications, and assays to quantify gene expression. Questions for deeper exploration in-class or online are provided.Related article in GENETICS: Hornos Carneiro MF, Shin N, Karthikraj R, Barbosa F Jr, Kannan K, Colaiácovo MP. Antioxidant CoQ10 restores fertility by rescuing bisphenol A-induced oxidative DNA damage in the Caenorhabditis elegans Germline. Genetics 214:381–395.

scholarly journals Elevated expression of the Sertoli cell androgen receptor disrupts male fertility

2016 ◽  
Vol 311 (2) ◽  
pp. E396-E404 ◽  
Author(s):  
Rasmani Hazra ◽  
Dannielle Upton ◽  
Reena Desai ◽  
Omar Noori ◽  
Mark Jimenez ◽  
...  
Keyword(s):  
Androgen Receptor ◽  
Germ Cell ◽  
Sertoli Cell ◽  
Germ Cells ◽  
Male Fertility ◽  
Leydig Cells ◽  
Cell Function ◽  
Pubertal Development ◽  
Receptor Expression ◽  
Testis Size

Recently, we created a unique gain-of-function mouse model with Sertoli cell-specific transgenic androgen receptor expression (TgSCAR) showing that SCAR activity controls the synchronized postnatal development of somatic Sertoli and Leydig cells and meiotic-postmeiotic germ cells. Moderate TgSCAR (TgSCARm) expression reduced testis size but had no effect on male fertility. Here, we reveal that higher TgSCAR expression (TgSCARH) causes male infertility. Higher SCAR activity, shown by upregulated AR-dependent transcripts ( Rhox5, Spinw1), resulted in smaller adult TgSCARH testes (50% of normal) despite normal or elevated circulating and intratesticular testosterone levels. Unlike fertile TgSCARm males, testes of adult TgSCARH males exhibited focal regions of interstitial hypertrophy featuring immature adult Leydig cells and higher intratesticular dihydrotestosterone and 5α-androstane 3α,17β-diol levels that are normally associated with pubertal development. Mature TgSCARH testes also exhibited markedly reduced Sertoli cell numbers (70%), although meiotic and postmeiotic germ cell/Sertoli cell ratios were twofold higher than normal, suggesting that elevated TgSCAR activity supports excessive spermatogenic development. Concurrent with the higher germ cell load of TgSCARH Sertoli cells were increased levels of apoptotic germ cells in TgSCARH relative to TgSCARm testes. In addition, TgSCARH testes displayed unique morphological degeneration that featured accumulated cellular and spermatozoa clusters in dilated channels of rete testes, consistent with reduced epididymal sperm numbers. Our findings reveal for the first time that excessive Sertoli cell AR activity in mature testes can reach a level that disturbs Sertoli/germ cell homeostasis, impacts focal Leydig cell function, reduces sperm output, and disrupts male fertility.

scholarly journals BMP4 promotes mouse iPS cell differentiation to male germ cells via Smad1/5, Gata4, Id1 and Id2

Reproduction ◽  
2017 ◽  
Vol 153 (2) ◽  
pp. 211-220 ◽  
Author(s):  
Shi Yang ◽  
Qingqing Yuan ◽  
Minghui Niu ◽  
Jingmei Hou ◽  
Zijue Zhu ◽  
...  
Keyword(s):  
Cell Differentiation ◽  
Germ Cell ◽  
Germ Cells ◽  
Real Time Pcr ◽  
Molecular Mechanisms ◽  
Ips Cells ◽  
Male Germ Cell ◽  
Western Blots ◽  
Male Germ Cells ◽  
Downstream Effectors

Generation of male germ cells from pluripotent cells could provide male gametes for treating male infertility and offer an ideal model for unveiling molecular mechanisms of spermatogenesis. However, the influence and exact molecular mechanisms, especially downstream effectors of BMP4 signaling pathways, in male germ cell differentiation of the induce pluripotent stem (iPS) cells, remain unknown. This study was designed to explore the role and mechanism of BMP4 signaling in the differentiation of mouse iPS cells to male germ cells. Embryoid body (EB) formation and recombinant BMP4 or Noggin were utilized to evaluate the effect of BMP4 on male germ cell generation from mouse iPS cells. Germ cell-specific genes and proteins as well as the downstream effectors of BMP4 signaling pathway were assessed using real-time PCR and Western blots. We found that BMP4 ligand and its multiple receptors, including BMPR1a, BMPR1b and BMPR2, were expressed in mouse iPS cells. Real-time PCR and Western blots revealed that BMP4 could upregulate the levels of genes and proteins for germ cell markers in iPS cells-derived EBs, whereas Noggin decreased their expression in these cells. Moreover, Smad1/5 phosphorylation, Gata4 transcription and the transcripts of Id1 and Id2 were enhanced by BMP4 but decreased when exposed to Noggin. Collectively, these results suggest that BMP4 promotes the generation of male germ cells from iPS cells via Smad1/5 pathway and the activation of Gata4, Id1 and Id2. This study thus offers novel insights into molecular mechanisms underlying male germ cell development.

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