Estradiol upregulates activating transcription factor 3, a candidate gene in the etiology of hypospadias

Neonatal exposure to bisphenol analogues disrupts genital development in male mice

The public concern and governmental regulations on bisphenol A (BPA) have stimulated the development and production of alternative analogues to replace BPA in a myriad of applications. Given the endocrine disrupting activities of BPA and potentially other analogues, the present study investigated and compared the effects of neonatal exposure to BPA, BPB, BPE, BPF, and BPS on the genital development in male mice. Pups were injected subcutaneously on the right shoulder in the mornings of postnatal days P0.5, P2, P4, and P6, resulting in a low dose of 0.05 μg/g body weight (bw)/day and a high dose of 10 μg/g bw/day. Mice were sacrificed at predetermined time and evaluated for gene expression levels (3 days after birth or P3), steroid hormone levels (P5), and morphological changes (P21). The results demonstrated that BPA, BPB, BPE, or BPF significantly shortened glans penis length and anogenital distance, while BPS didn't. Testis weight and anogenital distance were also significantly affected by BPA, BPE or BPF. The results also revealed that bisphenol analogues exposure significantly reduced testosterone levels, and altered the expression levels of developmental genes networks in developing penis of mice. Our data demonstrate that selected bisphenol analogues may possess similar endocrine disrupting effects compared to BPA, and exposure to these analogues could affect reproductive development of male mice. This raises the concern on the environmental and health safety of bisphenol analogues applied as industrial BPA replacements.

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.

New frontiers on the molecular underpinnings of hypospadias according to severity

Hypospadias, which is characterised by the displacement of the urethral meatus from its typical anatomical location in males, shows various degrees of severity. In this systematic review, we surveyed our current understanding of the genetics of isolated hypospadias in humans according to the severity of the condition. We found that sequencing and genotyping approaches were the preferred methods of study and that single nucleotide polymorphisms were the most common finding associated with hypospadias. Most genes fell into four gene-pathway categories related to androgens, oestrogens, growth factors, or transcription factors. Few hypospadias studies classify their findings by severity. Taken together, we argue that it is advantageous to take into consideration the severity of the condition in search of novel candidates in the aetiology of hypospadias. Abbreviations: AR: androgen receptor; ATF3: activating transcription factor 3; BMP4: bone morphogenetic protein 4; BMP7: bone morphogenetic protein 7; CYP17: steroid 17-alpha-hydroxylase/17,20 lyase; CYP1A1: cytochrome P450 1A1; CYP3A4: cytochrome P450 3A4; CNVs: copy number variants; DGKK: diacylglycerol kinase kappa; ESR1: oestrogen receptor 1; ESR2: oestrogen receptor 2; FGF8: fibroblast growth factor 8; FGF10: fibroblast growth factor 10; FGFR2: fibroblast growth factor receptor 2; HOXA4: homeobox protein Hox-A4; HOXB6: homeobox protein Hox-B6; HSD17B3: hydroxysteroid 17-beta dehydrogenase 3; MAMLD1: mastermind-like domain-containing protein 1; SF-1: splicing factor 1; SHH: sonic hedgehog; SNPs: single nucleotide polymorphisms; SOX9: SRY-box 9; SRD5A2: steroid 5 alpha-reductase 2; SRY: sex-determining region Y protein; STAR: steroidogenic acute regulatory protein; STARD3: StAR-related lipid transfer protein 3; STS: steryl-sulfatase; WT1: Wilms tumour protein; ZEB1: zinc finger oestrogen-box binding homeobox 1.

Androgen Receptor Expression in Hypospadias

Introduction:

The exact mechanism behind the development of hypospadias is unclear. Research studies on androgen receptor (AR) expression are controversial with results stating all possible outcomes – AR elevated, similar, or reduced when compared to normal.

Aims:

The aim is to study the AR expression and hormone levels in hypospadias patients and compare them with children having normal genitalia.

Methods:

Group 1 (controls) involved patients who underwent circumcision for phimosis while Group 2 involved hypospadias patients who did not receive any preoperative testosterone. Preoperative hormonal assay included luteinizing hormone, follicle-stimulating hormone, and free testosterone levels in all the patients. The foreskin specimen was analyzed for AR expression using immunohistochemistry (anti-AR antibody PathnSitu, clone R441, 1/100 dilution). AR staining was expressed as H score. The H score was calculated by multiplying the intensity of staining and the percentage of stained cells showing cytoplasmic positivity at high power (×40).

Results:

There were 27 patients in Group 1 while 16 in Group 2 (distal 10; proximal 6).There was no significant difference in the age distribution. The mean H score was significantly higher (189.5) in hypospadias patients compared to controls (97.5) and was significantly higher in proximal (220) compared to distal (159) hypospadias. There was no significant difference in hormone levels between groups.

Conclusion:

AR expression was significantly elevated in hypospadias patients. It was higher in proximal compared to distal hypospadias, probably due to end-organ overexpression. Further larger trials are likely to through light into this controversial subject.

Regulatory roles of epithelial-mesenchymal interaction (EMI) during early and androgen dependent external genitalia development

Development of external genitalia (ExG) has been a topic of long mystery in the field of organogenesis research. Early stage male and female of mouse embryos develop a common genital tubercle (GT) in the perineum whose outgrowth extends distally from the posterior cloacal regions. Concomitant with GT outgrowth, the cloaca is divided into urogenital sinus and anorectum by urorectal septum (URS) internally. The outgrowth of the GT is associated with the formation of endodermal epithelial urethral plate (UP) attached to the ventral epidermis of the GT. Such a common developmental phase is observed until around embryonic day 15.5 (E15.5) morphologically in mouse embryogenesis. Various growth factor genes, such as Fibroblast growth factor (Fgf) and Wnt genes are expressed and function during GT formation. Since the discovery of key growth factor signals and several regulatory molecules, elucidation of their functions has been achieved utilizing mouse developmental models, conditional gene knockout mouse and in vitro culture. Analyses on the phenotypes of such mouse models have revealed that several growth factor families play fundamental roles in ExG organogenesis based on the epithelial-mesenchymal interaction (EMI). More recently, EMI between developing urethral epithelia and its bilateral mesenchyme of later stages is also reported during subsequent stage of androgen-dependent male-type urethral formation in the mouse embryo. Mafb, belonging to AP-1 family and a key androgen-responsive mesenchymal gene, is identified and starts to be expressed around E14.5 when masculinization of the urethra is initiated. Mesenchymal cell condensation and migration, which are regulated by nonmuscle myosin, are shown to be essential process for masculinization. Hence, studies on EMI at various embryonic stages are important not only for early but also for subsequent masculinization of the urethra. In this review, a dynamic mode of EMI for both early and late phases of ExG development is discussed.

Timing of androgen receptor disruption and estrogen exposure underlies a spectrum of congenital penile anomalies

Congenital penile anomalies (CPAs) are among the most common human birth defects. Reports of CPAs, which include hypospadias, chordee, micropenis, and ambiguous genitalia, have risen sharply in recent decades, but the causes of these malformations are rarely identified. Both genetic anomalies and environmental factors, such as antiandrogenic and estrogenic endocrine disrupting chemicals (EDCs), are suspected to cause CPAs; however, little is known about the temporal window(s) of sensitivity to EDCs, or the tissue-specific roles and downstream targets of the androgen receptor (AR) in external genitalia. Here, we show that the full spectrum of CPAs can be produced by disrupting AR at different developmental stages and in specific cell types in the mouse genital tubercle. Inactivation of AR during a narrow window of prenatal development results in hypospadias and chordee, whereas earlier disruptions cause ambiguous genitalia and later disruptions cause micropenis. The neonatal phase of penile development is controlled by the balance of AR to estrogen receptor α (ERα) activity; either inhibition of androgen or augmentation of estrogen signaling can induce micropenis. AR and ERα have opposite effects on cell division, apoptosis, and regulation of Hedgehog, fibroblast growth factor, bone morphogenetic protein, and Wnt signaling in the genital tubercle. We identify Indian hedgehog (Ihh) as a novel downstream target of AR in external genitalia and show that conditional deletion of Ihh inhibits penile masculinization. These studies reveal previously unidentified cellular and molecular mechanisms by which antiandrogenic and estrogenic signals induce penile malformations and demonstrate that the timing of endocrine disruption can determine the type of CPA.

Increased gene copy number of VAMP7 disrupts human male urogenital development through altered estrogen action

Vesicle transport is intimately connected with key nuclear functions and transcriptional regulation. Here, children born with congenital genitourinary tract masculinization disorders were analyzed by array-Comparative Genomic Hybridization, which revealed the presence of de novo copy number gains on Xq28 encompassing the VAMP7 gene encoding a vesicle-trafficking protein. Humanized VAMP7 BAC transgenic mice displayed cryptorchidism, urethral defects, and hypospadias. Mutant mice exhibited reduced penile length, focal spermatogenic anomalies, diminished sperm motility, and subfertility. VAMP7 colocalized with estrogen receptor alpha (ESR1) in the presence of ligand. Elevated levels of VAMP7 markedly intensified ESR1 transcriptional activity by increasing ESR1 protein cellular content upon ligand stimulation and up-regulated the expression of estrogen-responsive genes including ATF3, CYR61, and CTGF, all of which are implicated in human hypospadias. Hence, increased gene dosage of the SNARE protein, VAMP7, enhances estrogen receptor action in male genitourinary tissues, affects the virilization of the reproductive tract, and results in genitourinary birth defects in humans.

Twenty-Four Genes are Upregulated in Patients with Hypospadias

Hypospadias is a congenital hypoplasia of the penis, with displacement of the urethral opening along the ventral surface, and has been reported to be one of the most common congenital anomalies, occurring in approximately 1:250 to 1:300 live births. As hypospadias is reported to be an easily diagnosed malformation at the crossroads of genetics and environment, it is important to study the genetic component in order to elucidate its etiology. In this study, the gene expression profiles both in human hypospadias tissues and normal penile tissues were studied by Human Gene Expression Array. Twenty-four genes were found to be upregulated. Among these, ATF3 and CYR61 have been reported previously. Other genes that have not been previously reported were also found to be upregulated: BTG2, CD69, CD9, DUSP1, EGR1, EIF4A1, FOS, FOSB, HBEGF, HNRNPUL1, IER2, JUN, JUNB, KLF2, NR4A1, NR4A2, PTGS2, RGS1, RTN4, SLC25A25, SOCS3 and ZFP36 (p <0.05). Further studies including genome-wide association studies (GWAS) with expression studies in a large patient group will help us for identifiying the candidate gene(s) in the etiology of hypospadias.

Ex vivo absorption of promestriene from oil-in-water emulsion into infant foreskin

Hypospadias is a birth defect in which the urinary tract opening is not at the tip of the penis. Hypospadias surgery is frequently complicated by healing deficiencies. Topical treatments with oestrogens were reported to improve healing. In the present study, ex vivo percutaneous absorption of promestriene, a synthetic oestrogen resulting of the double esterification of estradiol was conducted as a pre-requisite for further clinical trial in infants. Penetration of promestriene into infant foreskin treated with commercial oil in water emulsion (10 μg mg(-1)) for 24 h was characterized showing controlled release properties enabling epidermal concentration more than six times higher than dermal concentration (4.13±2.46 mg g(-1) versus 0.62±0.84 mg g(-1), respectively). Furthermore, apparent promestriene fluxes into and through the skin (i.e., 1.5 μg cm(-2) h(-1) and<0.89 μg cm(-2) h(-1), respectively) were calculated from (i) drug amount retained into epidermis and dermis, or (ii) the limit of detection into the receptor fluid. In conclusion, less than 2% of initial dose were absorbed within 24h which compared well with others steroids applied topically in colloidal systems.

Diethylstilboestrol exposure does not reduce testosterone production in human fetal testis xenografts

In rodents, in utero exposure to exogenous estrogens including diethylstilboestrol (DES) results in major suppression of steroidogenesis in fetal testes. Whether similar effects occur in the human fetal testis is equivocal. Based on the results of the rodent studies, we hypothesised that exposure of human fetal testes to DES would result in a reduction in testosterone production. We show, using a xenograft approach, that testosterone production is not reduced in human fetal testis following DES exposure. Human fetal testes (15–19 weeks’ gestation, n = 6) were xenografted into castrate male nude mice which were then treated for 35 days with vehicle or 100 µg/kg DES three times a week. For comparison, similar treatment was applied to pregnant rats from e13.5–e20.5 and effects on fetal testes evaluated at e21.5. Xenograft testosterone production was assessed by measuring host seminal vesicle (SV) weights as an indirect measure over the entire grafting period, and single measurement of serum testosterone at termination. Human fetal testis xenografts showed similar survival in DES and vehicle-exposed hosts. SV weight (44.3 v 26.6 mg, p = 0.01) was significantly increased in DES compared to vehicle-exposed hosts, respectively, indicating an overall increase in xenograft testosterone production over the grafting period, whilst serum testosterone at termination was unchanged. In contrast intra-testicular testosterone levels were reduced by 89%, in fetal rats exposed to DES. In rats, DES effects are mediated via Estrogen Receptor α (ESR1). We determined ESR1 protein and mRNA expression in human and rat fetal testis. ESR1 was expressed in rat, but not in human, fetal Leydig cells. We conclude that human fetal testis exposure to DES does not impair testosterone production as it does in rats, probably because ESR1 is not expressed in human fetal Leydig cells. This indicates that DES exposure is likely to pose minimal risk to masculinization of the human fetus.

Whole transcriptome analysis of the ERα synthetic fragment P295-T311 (ERα17p) identifies specific ERα-isoform (ERα, ERα36)-dependent and -independent actions in breast cancer cells

ERα17p is a peptide corresponding to the sequence P295LMIKRSKKNSLALSLT311 of the estrogen receptor alpha (ERα) and initially found to interfere with ERα-related calmodulin binding. ERα17p was subsequently found to elicit estrogenic responses in E2-deprived ERα-positive breast cancer cells, increasing proliferation and ERE-dependent gene transcription. Surprisingly, in E2-supplemented media, ERα17p-induced apoptosis and modified the actin network, influencing cell motility. Here, we report that ERα17p internalizes in breast cancer cells (T47D, MDA-MB-231, SKBR3) and induces a massive early (3 h) transcriptional activity. Remarkably, about 75% of significantly modified transcripts were also modified by E2, confirming the pro-estrogenic profile of ERα17p. The different ER spectra of the used cell lines allowed us to identify a specific ERα17p signature related to ERα as well as its variant ERα36. With respect to ERα, the peptide activates nuclear (cell cycle, cell proliferation, nucleic acid and protein synthesis) and extranuclear signaling pathways. In contrast, through ERα36, it mainly triggers inhibitory actions on inflammation. This is the first work reporting a detailed ERα36-specific transcriptional signature. In addition, we report that ERα17p-induced transcripts related to apoptosis and actin modifying effects of the peptide are independent from its estrogen receptor(s)-related actions. We discuss our findings in view of the potential use of ERα17p as a selective peptidomimetic estrogen receptor modulator (PERM).

Androgen receptor is overexpressed in boys with severe hypospadias, and ZEB1 regulates androgen receptor expression in human foreskin cells

INTRODUCTION

ZEB1 is overexpressed in patients with severe hypospadias. We examined the interaction between ZEB1 and the androgen receptor (AR) in vitro and the expression of AR in boys with hypospadias.

RESULTS

ZEB1 and AR colocalize to the nucleus. Estrogen upregulated ZEB1 and AR expression. Chromatin immunoprecipitation (ChIP) demonstrated that ZEB1 binds to an E-box sequence in the AR gene promoter. AR expression is higher in subjects with severe hypospadias than those with mild hypospadias and control subjects (P < 0.05). ZEB1 physically interacts with AR in human foreskin cells.

DISCUSSION

AR is overexpressed in patients with severe hypospadias. Environmental estrogenic compounds may increase the risk of hypospadias by facilitating the interaction between ZEB1 and AR.

METHODS

Hs68 cells, a fibroblast cell line derived from neonatal human foreskin, were exposed to 0, 10, and 100 nmol/l of estrogen, after which the cellular localization of ZEB1 and AR was assessed using immunocytochemistry. To determine if ZEB1 interacted with the AR gene, ChIP was performed using ZEB1 antibody and polymerase chain reaction (PCR) for AR. Second, AR expression was quantified using real-time PCR and western blot in normal subjects (n = 32), and subjects with mild (n = 16) and severe hypospadia (n = 16).

Hypospadias: interactions between environment and genetics

Hypospadias is one of the most common congenital malformations. It is considered to be a mild form of the 46,XY disorders of sex development (DSD), but its precise etiology remains to be elucidated. Compromised androgen synthesis or effects can cause this frequent malformation, although the mutational analyses of the genes involved in androgen actions have identified abnormalities in only a very small portion of patients. The overwhelming majority of cases remain unexplained and hypospadias may be a highly heterogeneous condition subject to multiple genetic and environmental factors. We here review the recent advances in this field and discuss the potential interactions between the environment and genetics.

ZEB1 is estrogen responsive in vitro in human foreskin cells and is over expressed in penile skin in patients with severe hypospadias

PURPOSE

We determined the effect of estrogen on ZEB1 in vitro and tested the hypothesis that ZEB1 is over expressed in the penile skin of subjects with hypospadias.

MATERIALS AND METHODS

Hs68 cells, a fibroblast cell line derived from human foreskin, were exposed to 0, 1, 10 and 100 nM estrogen, and the expression level of ZEB1 was assessed using reverse transcription real-time polymerase chain reaction, Western blot and immunocytochemical analysis. Next, preputial skin was prospectively collected from case and control subjects at hypospadias repair (37 cases) and circumcision (11). Hypospadias was classified as severe (13 cases) or mild (24) based on the position of the urethral meatus. ZEB1 expression was quantified using reverse transcription real-time polymerase chain reaction, Western blot and immunohistochemical analysis.

RESULTS

Estrogen increased ZEB1 expression at the mRNA and protein levels in Hs68 cells in a concentration dependent fashion (p <0.01). Subjects with severe hypospadias had significantly higher ZEB1 mRNA levels and protein expression compared to controls or subjects with mild hypospadias (both p <0.01). Subjects with severe hypospadias had increased expression of ZEB1 in the basal layers of the preputial epidermis.

CONCLUSIONS

Estrogen increases ZEB1 expression in a human foreskin fibroblast cell line in vitro. Furthermore, ZEB1 is significantly over expressed in the penile skin of subjects with severe hypospadias. We propose that ZEB1 overexpression may contribute to development of hypospadias and may mediate the effect of estrogen on developing external male genitalia.

Genetic pathway of external genitalia formation and molecular etiology of hypospadias

Hypospadias is one of the most common congenital disorders in males. Impaired fetal androgen action interferes with masculinization, including external genitalia formation, and can result in this anomaly; however, the molecular etiology remains unknown. Recent molecular approaches, including gene-targeting approaches in mice and single nucleotide polymorphisms analyses in humans, might provide an opportunity to identify the causative and risk factors of this anomaly. Several genes, such as sonic hedgehog, fibroblast growth factors, bone morphogenetic proteins, homeobox genes, and the Wnt family regulate external genitalia formation. Mastermind-like domain containing 1/chromosome X open reading frame 6 mutation and activating transcription factor 3 variants have been shown to be associated with the incidence of isolated hypospadias. In addition, this anomaly may be associated with a specific haplotype of the gene for estrogen receptor alpha, which mediates the estrogenic effects of environmental endocrine disruptors, and the effects of these disruptors on external genitalia formation might depend on individual genetic susceptibility. These molecular studies will refine our knowledge of the genetic mechanism involved in external genitalia formation, and lead to new strategies for the clinical management of hypospadias.

Estrogen effects on fetal penile and urethral development in organotypic mouse genital tubercle culture

PURPOSE

We developed an organotypic genital tubercle culture system in vitro and used it to investigate the direct effects of the hyperestrogenic state on fetal mouse penile and urethral development.

MATERIALS AND METHODS

Genital tubercles were dissected from embryonic day 14.5 C57B/L6 male mouse fetuses and cultured using an air-liquid interface on a microporous membrane support soaked in synthetic medium. Cultures were separated into 4 groups. Groups 1 to 3 were supplied with 10 nM dihydrotestosterone, estradiol and 10 nM dihydrotestosterone plus estradiol, respectively. Group 4 was cultured in hormone-free medium. After 36 to 72-hour culture morphological, histological, proliferation, apoptosis, androgen signaling and activating transcription factor 3 analyses were done.

RESULTS

The physiological concentration of 10 nM dihydrotestosterone was essential for genital tubercle growth in vitro. Androgen induced growth and urethral development were significantly suppressed by high dose estrogen. Concurrently we observed increased apoptosis and decreased proliferation in the mesenchyma. Androgen signaling was disrupted and activating transcription factor 3, a factor related to hypospadias genesis, was up-regulated.

CONCLUSIONS

High dose estrogen suppressed male genital tubercle development in vitro. The organotypic genital tubercle culture system in vitro consisting of urethral epithelial and mesenchymal cells can recapitulate the hormonal sensitivity of fetal penile and urethral development. This method is potentially useful for studying the effects of various factors, particularly endocrine disruptors.

Clinical dilemmas and surgical treatment of penoscrotal, scrotal and perineal hypospadias

Hypospadia is the most common congenital malformation of the urinary tract. It is a malformation with the opening of the urethra proximally from the usual site. The meatal opening can be anywhere alone the shaft of the penis, or in more severe forms, within the scrotum, or in the perineum. Consequently the hypospadias can be distal, medial and proximal. The proximal ones can be penoscrotal (PS), scrotal (SC) and perineal (PE). The cause of hypospadias is largely unknown; however, current epidemiology and laboratory studies have shed new light into the etiology of hypospadias. With recent advancements in molecular biology, microarray technology, it appears that hypospadias is potentially related to disrupted gene expression. Currently, the only available treatment is surgery. The aim of this study was to present our results of the surgical correction of hypospadias and methods used to answer the clinical dilemmas about the gender. Authors have used two methods for a surgical resolution of the hypospadia - one-step operation suggested by Snodgrass and two-step operation, employing free graft suggested by Bracka. Clinical dilemmas regarding the gender were answered using cytogenetic assessment through lymphocyte cultivation method, suggested by Seabright. The cytogenetic assessment was carried in 23 patients with proximal hypospadia (penoscrotal, scrotal and perineal). Characteristic male cariotype (46, XY) was found in 22 patients. In one patient, with scrotal hypospadia, we found the characteristic female cariotype. This patient had testicles. The patient with female cariotype had a TDG gene that determines the differentiation of the testicles. Although surgery remains the only therapy for the treatment of the hypospadias, better understanding of the molecular and hormonal mechanisms behind the diseases may contribute to the prevention and the decrease in the incidence of the malformation. Cytogenetic testing in patients with unclear gender is important in planning further treatment.

Di-(2-ethylhexyl) phthalate upregulates ATF3 expression and suppresses apoptosis in mouse genital tubercle

OBJECTIVES

To investigate the effect of di-(2-ethylhexyl) phthalate (DEHP) on the expression of activating transcription factor 3 (ATF3) and apoptosis of fetal mouse genital tubercle (GT).

METHODS

In this developmental toxicity study, pregnant C57BL/6 mice were exposed to corn oil or DEHP (100 or 500 mg/kg/day) from embryonic day 12 (ED12) to ED16. Apoptosis was characterized by Terminal transferase dUTP nick end labeling (TUNEL) assay. Using RT-PCR and western blot, the expressions of ATF3 and apoptosis-related genes (P53, Bcl-2 and Bax) were investigated.

RESULTS

Apoptosis of fetal mouse GT cells notably decreased after DEHP treatment. DEHP activated ATF3 both at the mRNA and protein levels in GT. Furthermore, pro-apoptotic P53 was downregulated and the ratio of anti-apoptotic (Bcl-2)/pro-apoptotic (Bax) was not significantly changed.

CONCLUSIONS

These results suggest that DEHP may induce external genital defects via a mechanism involving apoptosis, which might correlate with the regulation of ATF3 and P53 expressions.

Is hypospadias a genetic, endocrine or environmental disease, or still an unexplained malformation?

Hypospadias is one of the most frequent genital malformations in the male newborn and results from an abnormal penile and urethral development. This process requires a correct genetic programme, time- and space-adapted cellular differentiation, complex tissue interactions, and hormonal mediation through enzymatic activities and hormonal transduction signals. Any disturbance in these regulations may induce a defect in the virilization of the external genitalia and hypospadias. This malformation thus appears to be at the crossroads of various mechanisms implicating genetic and environmental factors. The genes of penile development (HOX, FGF, Shh) and testicular determination (WT1, SRY) and those regulating the synthesis [luteinizing hormone (LH) receptor] and action of androgen (5alpha reductase, androgen receptor) can cause hypospadias if altered. Several chromosomal abnormalities and malformative syndromes include hypospadias, from anterior to penoscrotal forms. More recently, CXorf6 and ATF3 have been reported to be involved. Besides these genomic and hormonal factors, multiple substances found in the environment can also potentially interfere with male genital development because of their similarity to hormones. The proportion of hypospadias cases for which an aetiology is detected varies with the authors but it nevertheless remains low, especially for less severe cases. An interaction between genetic background and environment is likely.