Is activating transcription factor 3 up-regulated in patients with hypospadias?

c-Fos is upregulated in the genital tubercle of DEHP-induced hypospadiac rats and the prepuce of patients with hypospadias

This study aimed to investigate the expression of Fos proto-oncogene, AP-1 transcription factor subunit (c-Fos) in the genital tubercle (GT) of rats with di(2-ethylhexyl) phthalate (DEHP)-induced hypospadias and in the prepuce of patients with hypospadias compared with unaffected controls. Pregnant rats were given 750 mg/kg/day DEHP orally from gestational days 12-19. Western blotting showed that c-Fos expression was increased in DEHP-induced hypospadiac male offspring. In addition, 30 prepuce tissue specimens obtained during hypospadias repair surgery were divided into 2 groups: the mild hypospadias group (n = 15) and the severe hypospadias group (n = 15). Fifteen normal prepuce tissue specimens were harvested during elective circumcision as normal controls. Real-time quantitative polymerase chain reaction, western blotting and immunohistochemistry analyses were used to assess c-Fos expression. c-Fos protein levels were higher in the GT of DEHP-induced rats than in that of control rats. c-Fos mRNA and protein levels were also higher in the hypospadias groups than in the control group (p < 0.05, p < 0.001), and c-Fos protein levels were significantly higher in the severe hypospadias group than in the mild hypospadias group (p < 0.01). The expression of c-Fos was increased in both the GT of DEHP-induced hypospadiac rats and the prepuce of hypospadias patients. Thus, c-Fos overexpression might contribute to hypospadias.Abbreviations: DEHP: di(2-ethylhexyl) phthalate; c-Fos: Fos proto-oncogene, AP-1 transcription factor subunit; Mafb: the masculinization-regulatory gene v-maf musculoaponeurotic fibrosarcoma oncogene family, protein B; GT: genital tubercle; ED: embryonic day; AGD: anogenital distance; AGI: anogenital distance index; ED: embryonic day.

A Proteomics Signature of Mild Hypospadias: A Pilot Study

Background and Objective: Mild hypospadias is a birth congenital condition characterized by the relocation of the male urethral meatus from its typical anatomical position near the tip of the glans penis, to a lower ventral position up to the brim of the glans corona, which can also be accompanied by foreskin ventral deficiency. For the most part, a limited number of cases have known etiology. We have followed a high-throughput proteomics approach to study the proteome in mild hypospadias patients. Methods: Foreskin samples from patients with mild hypospadias were collected during urethroplasty, while control samples were collected during elective circumcision (n = 5/group). A high-throughput, quantitative proteomics approach based on multiplexed peptide stable isotope labeling (SIL) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis was used to ascertain protein abundance changes in hypospadias patients when compared to control samples. Results: A total of 4,815 proteins were quantitated (2,522 with at least two unique peptides). One hundred and thirty-three proteins from patients with mild hypospadias showed significant abundance changes with respect to control samples, where 38 proteins were increased, and 95 proteins were decreased. Unbiased functional biological analysis revealed that both mitochondrial energy production and apoptotic signaling pathways were enriched in mild hypospadias. Conclusions: This first comprehensive proteomics characterization of mild hypospadias shows molecular changes associated with essential cellular processes related to energy production and apoptosis. Further evaluation of the proteome may expand the search of novel candidates in the etiology of mild hypospadias and could also lead to the identification of biomarkers for this congenital urogenital condition.

Synergistic effect of siRNA-mediated silencing of TGF-β R1 and TGF-β R2 genes on the proliferation and apoptosis of penile urethral epithelial cells in hypospadiac male rats

The study elucidated the effects associated with silencing growth factor-β R1 (TGF-β R1) and TGF-β R2 genes on the proliferation and apoptosis of penile urethral epithelial cells (UECs) in hypospadiac male rats. Seventy-five male rats were distributed into the normal, model, TGF-β R1/2-siRNA, TGF-β R1-siRNA and TGF-β R2-siRNA groups. The UECs of the rats included in the study were cultured in vitro and subsequently divided into the control, blank, TGF-β R1/2-siRNA, TGF-β R1-siRNA and TGF-β R2-siRNA groups. The mRNA and protein expressions of TGF-β R1/R2 were measured by quantitative real-time polymerase chain reaction (qRT-PCR) and western blotting. Cell proliferation and apoptosis were evaluated by cell counting kit-8 (CCK-8) assay as well as by flow cytometry. Compared with the normal group, the apoptotic rate of the UECs in the model, TGF-β R1/2-siRNA, TGF-β R1-siRNA and TGF-β R2-siRNA groups displayed remarkable increases; compared with the model group, the apoptotic rate of the UECs in the TGF-β R1/2-siRNA, TGF-β R1-siRNA and TGF-β R2-siRNA groups displayed significant decreases, similar observations were made regarding mRNA and protein expressions of TGF-β R1 and TGF-β R2. Compared with the TGF-β R1/2-siRNA group, the apoptotic rates of the UECs in the TGF-β R1-siRNA and TGF-β R2-siRNA groups were up regulated, while cell proliferation in the TGF-β R1-siRNA and TGF-β R2-siRNA groups decreased accompanied by an increased rate of apoptosis. This study ultimately demonstrated that the silencing of TGF-β R1 and TGF-β R2 genes could promote cell proliferation and inhibit apoptosis of penile UECs in hypospadiac male rats.

The Genetic and Environmental Factors Underlying Hypospadias

Hypospadias results from a failure of urethral closure in the male phallus and affects 1 in 200-300 boys. It is thought to be due to a combination of genetic and environmental factors. The development of the penis progresses in 2 stages: an initial hormone-independent phase and a secondary hormone-dependent phase. Here, we review the molecular pathways that contribute to each of these stages, drawing on studies from both human and mouse models. Hypospadias can occur when normal development of the phallus is disrupted, and we provide evidence that mutations in genes underlying this developmental process are causative. Finally, we discuss the environmental factors that may contribute to hypospadias and their potential immediate and transgenerational epigenetic impacts.

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.

Aetiology of hypospadias: a systematic review of genes and environment

BACKGROUND

Hypospadias is a common congenital malformation of the male external genitalia. Most cases have an unknown aetiology, which is probably a mix of monogenic and multifactorial forms, implicating both genes and environmental factors. This review summarizes current knowledge about the aetiology of hypospadias.

METHODS

Pubmed was used to identify studies on hypospadias aetiology published between January 1995 and February 2011. Reference lists of the selected manuscripts were also searched to identify additional studies, including those published before 1995.

RESULTS

The search provided 922 articles and 169 articles were selected for this review. Studies screening groups of patients with hypospadias for single gene defects found mutations in WT1, SF1, BMP4, BMP7, HOXA4, HOXB6, FGF8, FGFR2, AR, HSD3B2, SRD5A2, ATF3, MAMLD1, MID1 and BNC2. However, most investigators are convinced that single mutations do not cause the majority of isolated hypospadias cases. Indeed, associations were found with polymorphisms in FGF8, FGFR2, AR, HSD17B3, SRD5A2, ESR1, ESR2, ATF3, MAMLD1, DGKK, MID1, CYP1A1, GSTM1 and GSTT1. In addition, gene expression studies indentified CTGF, CYR61 and EGF as candidate genes. Environmental factors consistently implicated in hypospadias are low birthweight, maternal hypertension and pre-eclampsia, suggesting that placental insufficiency may play an important role in hypospadias aetiology. Exogenous endocrine-disrupting chemicals have the potential to induce hypospadias but it is unclear whether human exposure is high enough to exert this effect. Other environmental factors have also been associated with hypospadias but, for most, the results are inconsistent.

CONCLUSIONS

Although a number of contributors to the aetiology of hypospadias have been identified, the majority of risk factors remain unknown.