Expression of the androgen receptor and 5 alpha-reductase type 2 in the developing human fetal penis and urethra

Epigenetic insights to pediatric uropathology: Celebrating the fundamental biology vision of Tony Khoury

INTRODUCTION

Many pediatric urology conditions affect putatively normal tissues or appear too commonly to be based solely on specific DNA mutations. Understanding epigenetic mechanisms in pediatric urology, therefore, has many implications that can impact cell and tissue responses to settings, such as environmental and hormonal influences on urethral development, uropathogenic infections, obstructive stimuli, all of which originate externally or extracellularly. Indeed, the cell's response to external stimuli is often mediated epigenetically. In this commentary, we highlight work on the critical role that epigenetic machinery, such as DNA methyltransferases (DNMTs), Enhancer of Zeste Polycomb Repressive Complex 2 Subunit (EZH2), and others play in regulating gene expression and cellular functions in three urological contexts.

DESIGN

Animal and cellular constructs were used to model clinical pediatric uropathology. The hypertrophy, trabeculation, and fibrosis of the chronically obstructed bladder was explored using smooth muscle cell models employing disorganised vs. normal extracellular matrix (ECM), as well as a new animal model of chronic obstructive bladder disease (COBD) which retains its pathologic features even after bladder de-obstruction. Cell models from human and murine hypospadias or genital tubercles (GT) were used to illustrate developmental responses and epigenetic dependency of key developmental genes. Finally, using bladder urothelial and organoid culture systems, we examined activity of epigenetic machinery in response to non uropathogenic vs. uropathogenic E.coli (UPEC). DNMT and EZH2 expression and function were interrogated in these model systems.

RESULTS

Disordered ECM exerted a principal mitogenic and epigenetic role for on bladder smooth muscle both in vitro and in CODB in vivo. Key genes, e.g., BDNF and KCNB2 were under epigenetic regulation in actively evolving obstruction and COBD, though each condition showed distinct epigenetic responses. In models of hypospadias, estrogen strongly dysregulated WNT and Hox expression, which was normalized by epigenetic inhibition. Finally, DNA methylation machinery in the urothelium showed specific activation when challenged by uropathogenic E.coli. Similarly, UPEC induces hypermethylation and downregulation of the growth suppressor p16INK4A. Moreover, host cells exposed to UPEC produced secreted factors inducing epigenetic responses transmissible from one affected cell to another without ongoing bacterial presence.

DISCUSSION

Microenvironmental influences altered epigenetic activity in the three described urologic contexts. Considering that many obstructed bladders continue to display abnormal architecture and dysfunction despite relief of obstruction similar to after resection of posterior valves or BPH, the epigenetic mechanisms described highlight novel approaches for understanding the underlying smooth muscle myopathy of this crucial clinical problem. Similarly, there is evidence for an epigenetic basis of xenoestrogen on development of hypospadias, and UTI-induced pan-urothelial alteration of epigenetic marks and propensity for subsequent (recurrent) UTI. The impact of mechanical, hormonal, infectious triggers on genitourinary epigenetic machinery activity invite novel avenues for targeting epigenetic modifications associated with these non-cancer diseases in urology. This includes the use of deactivated CRISPR-based technologies for precise epigenome targeting and editing. Overall, we underscore the importance of understanding epigenetic regulation in pediatric urology for the development of innovative therapeutic and management strategies.

Exploring rat corpus cavernosum alterations induced by finasteride treatment and withdrawal

Despite its efficacy for treating androgenetic alopecia, finasteride, an inhibitor of 5α-reductase (i.e., the enzyme converting testosterone, T, into dihydrotestosterone, DHT), is associated with several side effects including sexual dysfunction (e.g., erectile dysfunction). These side effects may persist after drug suspension, inducing the so-called post-finasteride syndrome (PFS). The effects of subchronic treatment with finasteride (i.e., 20 days) and its withdrawal (i.e., 1 month) in rat corpus cavernosum have been explored here. Data obtained show that the treatment was able to decrease the levels of the enzyme 5α-reductase type II in the rat corpus cavernosum with increased T and decreased DHT levels. This local change in T metabolism was linked to mechanisms associated with erectile dysfunction. Indeed, by targeted metabolomics, we reported a decrease in the nitric oxide synthase (NOS) activity, measured by the citrulline/arginine ratio and confirmed by the decrease in NO2 levels, and a decrease in ornithine transcarbamylase (OTC) activity, measured by citrulline/ornithine ratio. Interestingly, the T levels are negatively correlated with NOS activity, while those of DHT are positively correlated with OTC activity. Finasteride treatment also induced alterations in the levels of other molecules involved in the control of penile erection, such as norepinephrine and its metabolite, epinephrine. Indeed, plasma levels of norepinephrine and epinephrine were significantly increased and decreased, respectively, suggesting an impairment of these mediators. Interestingly, these modifications were restored by suspension of the drug. Altogether, the results reported here indicate that finasteride treatment, but not its withdrawal, affects T metabolism in the rat corpus cavernosum, and this alteration was linked to mechanisms associated with erectile dysfunction. Data here reported could also suggest that the PFS sexual side effects are more related to dysfunction in a sexual central control rather than peripheral compromised condition.

Evaluation of androgen receptor markers in erectile dysfunction

BACKGROUND

Steroid hormones, such as testosterone, play a crucial role in modulating the development of male internal and external genitalia as well as secondary sex characteristics by binding to the androgen receptor. Once bound, androgen receptor operates as an inducible transcription factor, interacting with a multitude of co-regulators to initiate various downstream signaling pathways. The androgen saturation hypothesis posits that beyond a specific threshold, androgen receptor binding and functionality remain unaltered despite an increase in serum testosterone levels.

OBJECTIVES

The objective of this study was to explore the expression of these proteins in penile tissue samples from men with severe erectile dysfunction to enhance our understanding of the influence of serum testosterone on androgen receptor function.

MATERIALS AND METHODS

Patients undergoing surgical management for high-grade ED at our institution were invited to participate in the study. During inflatable penile prosthesis surgery, corpus cavernosum biopsy was obtained. Protein was extracted from each sample for western blot analysis which was probed with androgen receptor, heme oxygenase, inducible nitric oxide synthase, and phosphodiesterase type 5 antibodies with GAPDH for protein normalization.

RESULTS

12 men agreed to participate in this study. Serum testosterone levels were obtained from all participants on the morning of their surgery. The median testosterone level was 300.15 ng/dL. Our findings revealed a decrease in androgen receptor and inducible nitric oxide synthase expression at serum testosterone levels below 300 ng/dL (p = 0.022, 0.03). Similarly, hemeoxygenase and phosphodiesterase type 5 expression levels were significantly lower at serum T concentrations below 200 ng/dL (p = 0.017, 0.014).

DISCUSSION AND CONCLUSION

These data showed a significant decrease in the expression of proteins downstream of the androgen receptor at lower serum T levels. This suggests a potential correlation between serum T concentration and androgen receptor signaling and supports a potential saturation value between 200 and 300 ng/dL.

Hormone receptor expression in hypospadias

INTRODUCTION

Sex hormone imbalance in utero is hypothesized to play an important role in the pathogenesis of hypospadias. Due to its easy accessibility, foreskin samples have been used to describe hormone receptor expression in rodents, and both adult and pediatric patients. In this study we conducted a systematic approach to assess hormone receptor expression in pediatric patients with hypospadias compared to healthy controls with a focus on age-matching and differences in severity and degree of hypospadias.

METHODS

Foreskin samples were collected from 35 children during hypospadias operations (18 distal and 17 proximal hypospadias) and compared with ventral foreskin samples of a control group of 32 children during circumcision (15 age-matched and 17 older boys). The samples were stained with H/E, androgen (AR), estrogen (ER) and progesterone receptors (PR). The receptor stainings were blindly evaluated. An Allred score was used to evaluate receptor expression in both the epithelium as well as stroma.

RESULTS

AR was detected in all cases. AR expression in the stroma was more evident than in the epithelium. AR expression in the hypospadias groups was significantly less than the age matched controls (p < 0.05). There was no significant difference between the two hypospadias groups nor between the two control groups. Older control group showed significantly elevated levels of AR expression compared to the hypospadias group (p < 0.05). ER was also detected in all cases. The stroma showed more ER than in epithelium. PR was minimal or negative in all samples.

CONCLUSION

Boys with hypospadias showed significantly weaker expression of androgen receptors than age matched controls. The severity of hypospadias did not influence hormone receptor distribution. AR expression is better observed in the stroma than in the epithelium. There was no difference in ER expression between the hypospadias group (distal or proximal) and age matched normal controls. ER was expressed in larger numbers in normal older preputial tissue. The foreskin of prepubertal boys shows little to no expression of PR.

"Exogenous" 5 Alpha Reductase Deficiency: A Case Report

Testosterone and dihydrotestosterone are significant drivers of male external genital development, and therefore teratogens that alter these hormone profiles have been hypothesized to cause aberrations in development. Here, we present the first case report of genitalia anomalies after prenatal exposure to spironolactone and dutasteride through 8-weeks of gestation. The patient was born with abnormal male external genitalia which was surgically managed. Long-term outcomes such as gender identity, sexual function, hormonal maturation through puberty, and fertility remain unknown. These numerous considerations necessitate multi-disciplinary management with close follow-up to address sexual, psychological, and anatomic concerns.

A Genetics Study in the Foreskin of Boys with Hypospadias

Introduction

Hypospadias is a malformation of the genitourinary system in males, characterized by the placement of the urethral opening in the ventral surface of the penis. Although controversies continue about etiology, endocrine disrupting chemicals that disrupt normal endocrine signaling at the receptor or signal transduction level are thought to play an essential role in etiology. This study aimed to investigate the receptor gene expressions of the sex hormones and FGFR2, HOXA13, and TGFB1, which are considered to play an essential role in developing hypospadias.

Methods

The samples from the foreskin of 26 patients with hypospadias and 26 healthy children who underwent circumcision operations were collected. ESR1, AR, FGFR2, HOXA13, and TGFB gene expressions were investigated by real-time PCR in samples obtained during surgery.

Results

In the hypospadias group, ESR1 expression was increased (p = 0.013), and AR and FGFR2 expressions were decreased, which were found to be statistically significant (p = 0.027 and p = 0.003, respectively). There was no statistically significant difference between hypospadias and control groups in TGFBand HOXA13expression levels (p > 0.05).

Discussion

The results suggest that sex hormone receptors and FGFR2 may play an essential role in developing male external genital structures at the gene level. The defects in the expression of these genes can contribute to understanding the development of hypospadias.

Quantification of the Androgen and Estrogen Receptors in the Penile Tissues of Hypospadias in Comparison with Normal Children

INTRODUCTION

Hypospadias is a common congenital abnormality typified by a proximally placed ectopic urethral meatus along the ventral surface of the penis. Androgen receptor (AR) and estrogen receptor (ER) expression in the hypospadias tissues may be altered in hypospadias.

METHODOLOGY

We evaluated by immunohistochemistry the AR and ER expression in 75 tissues from hypospadias repair, and compared this expression to that of tissue from 75 patients undergoing circumcision. We also compared the intensity of AR and ER expression between different severities of hypospadias.

RESULTS

AR quantitative grading score decreased with severity of hypospadias, while the ER score increased as the hypospadias worsened, which was statistically significant (p-value <0.05).

CONCLUSION

The penile tissue AR expression is decreased and ER expression is increased with increasing severity of hypospadias.

Congenital Anterior Urethral Diverticulum in Identical Twins

Congenital anterior urethral diverticulum (CAUD) is an uncommon abnormality of the male urethra. In the literature, cases of CAUD affecting both children within a set of identical twins or presenting concomitantly with another urethral condition are exceedingly rare. We describe 2 cases of CAUD in identical twins: a pair of newborns in which Twin 1A and Twin 1B both present with CAUD, and a second pair of newborns in which only Twin 2A presents with CAUD along with a partial collateral urethral duplication. In doing so, we aim to add to the incomplete literature on the embryological development of CAUD.

Utility of genetic work-up for 46, XY patients with severe hypospadias

OBJECTIVE

Hypospadias is a common congenital abnormality that has been increasing in prevalence over the last decades. Historically, 46, XY patients with severe hypospadias and descended scrotal testes at birth have frequently lacked a genetic diagnosis. Platforms for molecular genetic testing have become more readily available and can offer an insight into underlying genetic causes of severe hypospadias. The goal of this study was to define the anatomical characteristics of severe hypospadias that can accurately define patients with 46, XY severe hypospadias and determine the practical utility of performing molecular genetic testing in this group of patients.

METHODS

Patients who met the criteria for 46, XY severe hypospadias were offered a molecular genetic work-up in consultation with pediatric genetics. Patients were identified through chart review. Data extracted included karyotype, hypospadias phenotype including stretched penile length at diagnosis, age at genetic diagnosis, molecular genetic testing, pathogenic gene variant(s), gender identity, and clinical course. All patients underwent clinical genetic testing via 46, XY Disorders of Sexual Development (DSD) panels offered by Invitae®, GeneDx®, or Blueprint Genetics®.

RESULTS

Of the 14 patients that underwent genetic testing, there were 5 previously 27 published and 3 novel pathogenic or likely pathogenic variants in genes associated with 28 46, XY severe hypospadias Table. Pathogenic variants were identified in AR (3), 29 SRD5A2 [1], NR5A1 [2], WT1 [1], and ARTX [1]. Two patients had a variant of unknown significance, one in FREM2 and another in CEP41. Four had negative gene panels. The patient with the WT1 pathogenic variant was subsequently found to have developed a Wilms tumor and the patients with NR5A1 pathogenic variants are now undergoing adrenal insufficiency surveillance.

DISCUSSION/CONCLUSION

Patients with 46,XY severe hypospadias and descended testes in the scrotum at birth can benefit from molecular genetic testing as their underlying disorders may reveal pathogenic variants that could have potentially life-altering consequences and change surveillance and monitoring.

Spatiotemporal map of key signaling factors during early penis development

The formation of the external genitalia is a highly complex developmental process, considering it involves a wide range of cell types and results in sexually dimorphic outcomes. Development is controlled by several secreted signalling factors produced in complex spatiotemporal patterns, including the hedgehog (HH), bone morphogenic protein (BMP), fibroblast growth factor (FGF) and WNT signalling families. Many of these factors act on or are influenced by the actions of the androgen receptor (AR) that is critical to masculinisation. This complexity of expression makes it difficult to conceptualise patterns of potential importance. Mapping expression during key stages of development is needed to develop a comprehensive model of how different cell types interact in formation of external genitalia, and the global regulatory networks at play. This is particularly true in light of the sensitivity of this process to environmental disruption during key stages of development. The goal of this review is to integrate all recent studies on gene expression in early penis development to create a comprehensive spatiotemporal map. This serves as a resource to aid in visualising potentially significant interactions involved in external genital development.

Diagrams of published RNA and protein localisation data for key secreted signalling factors during early penis development.

Unconventional expression patterns are identified that suggest novel signalling axes during development.

Key research gaps and limitations are identified and discussed.

Development of a putative adverse outcome pathway network for male rat reproductive tract abnormalities with specific considerations for the androgen sensitive window of development

Structured approaches like the adverse outcome pathway (AOP) framework offer great potential for depicting complex toxicological processes in a manner that can facilitate informed integration of mechanistic information in regulatory decisions. While this concept provides a structure for organizing evidence and facilitates consistency in evidence integration; the process, inputs, and manner in which AOPs and AOP networks are developed is still evolving. Following the OECD guiding principles of AOP development, we propose three AOPs for male reproductive tract abnormalities and derive a putative AOP network. The AOPs were developed using a fundamental understanding of the developmental biology of the organs of interest, paying close attention to the gestational timing of key events (KEs) to very specifically inform the domain of life stage applicability for the key event relationships (KERs). Chemical stressor data primarily from studies on low molecular weight phthalates (LMWPs) served to 'bound' the pathways of focus in this dynamic period of development and were integrated with the developmental biology data through an iterative process to define KEs and conclude on the extent of evidence in support of the KERs. The AOPs developed describe the linkage between 1) a decrease in Insl3 gene expression and cryptorchidism, 2) the sustained expression of Coup-tfII and hypospadias and 3) the sustained expression of Coup-tfII and altered Wolffian duct development/ epididymal agenesis. A putative AOP network linking AOP2 and AOP3 through decreased steroidogenic biosynthetic protein expression and converging of all AOPS at the population level impaired fertility adverse outcome is proposed. The network depiction specifies and displays the KEs aligned with their occurrence in gestational time. The pathways and network described herein are intended to catalyze collaborative initiatives for expansion into a larger network to enable effective data collection and inform alternative approaches for identifying stressors impacting this sensitive period of male reproductive tract development.

Molecular genetic analysis of AKR1C2-4 and HSD17B6 genes in subjects 46,XY with hypospadias

BACKGROUND

The formation of the male urethra depends to enzyme-mediated testosterone (T) conversion into 5α-dihydrotestosterone (DHT). Two metabolic pathways could be operating in the fetal testis to synthesize androgens: 1) the "classic" route (T→DHT) mediated by SRD5A2 and 2) a "backdoor" pathway in which DHT is synthesized by aldo-keto reductase family 1, member C2 (AKR1C2), AKR1C3, and AKR1C4 enzymes without formation of a T intermediate.

OBJECTIVE

We studied four genes of the "backdoor" pathway in karyotypic males with hypospadias to ascertain whether gene defects in AKRs impair urethral DHT formation that result in hypospadias.

DESIGN AND PATIENTS

The coding regions of the AKR1C2-4 and HSD17B6 genes were analyzed by PCR-SSCP and sequencing in a cohort of 25 Mexican patients (0.3-9 year-old-children) with 46,XY-hypospadias. Chi-squared tests was performed to evaluate the distribution of genotypes, alleles, and the Hardy-Weinberg (H-W) equilibrium. The effect of the genetic variants was investigated by in silico studies.

RESULTS

Screening studies revealed distinct genotypic patterns at different exons of AKR1C2-4 whereas HSD17B6 presented a wild-type sequence. The DNA analyses detected two synonymous variants (c.327C>T, c.666T>C/unreported) in AKR1C2. The AKR1C3 had two variants (c.15C>G, c.230A>G), two unreported variants (c.538T>C, c.596G>A), and one silent variant (c.312G>A). Two variants (c.434C>G, c.931C>G) were identified in AKR1C4. All variants were in H-W equilibrium without structural changes.

DISCUSSION

Hypospadias have been associated with defects that alter androgen biosynthesis in the human fetal testis, specifically 5α-DHT. We selected four candidate genes involved in the "backdoor" pathway for the formation of 5α-DHT. Molecular assays of the AKR1C2, AKR1C3, and AKR1C4 genes revealed a total of nine genetic single nucleotide variants. Several variants in the AKR1C genes have been associated with a variety of human pathologies. However, our studies suggest that active steroid biosynthesis via AKR1C might not be involved in hypospadias. Additionally, genetic research suggests a low involvement in the "backdoor" 5α-DHT pathway during human sexual development, specifically, the differentiation of male external genitalia.

CONCLUSION

These results indicate that substitutions in AKR1C2-4 are polymorphisms and all genetic variants lacks deleterious significant association with hypospadias. The data suggest that inactivating mutations in the AKR1C2-4 and HSD17B6 genes are an infrequent cause of hypospadias, which might weaken the contribution of the "backdoor" pathway to embryonic urethral masculinization.

Stretched penile length and total serum testosterone in term male neonates

Introduction

the reference values of stretched penile length vary with different ethnic group. There is paucity of data on the reference range of total serum testosterone in neonates especially in Africa. This study therefore was to determine the normal stretched penile length, total serum testosterone levels in term male newborns and to correlate them with anthropometric parameters.

Methods

this was a prospective cross-sectional study. One hundred and twenty-four consecutive healthy term male neonates were recruited in the first 72 hours of postnatal life. The stretched penile length (SPL) was measured with a rigid metric ruler. Weight, length and occipitofrontal circumference were also measured. Total serum testosterone level was determined using Enzyme Linked Immunoassay. Data were analysed using the Statistical Package for Social Sciences for Windows version 20.

Results

a total of 124 term male neonates were recruited. The postnatal age of recruited neonates was one to 70 hours with a mean of 22.8 ± 17.6 hours and the mean of estimated gestation age was 38.5 ± 1.3 weeks. The range of stretched penile length was from 2.1 to 3.9 cm with a mean of 3.2 ± 0.4 cm and SPL less than 2.2 cm was considered as micropenis. The mean total serum testosterone level was 357.4 ± 241.7 ng/dl. The SPL had a positive correlation with the birth weight, length and total serum testosterone. The total serum testosterone and birth length were predictors of stretched penile length.

Conclusion

among the studied population the mean stretched penile length was 3.2 cm and mean total serum testosterone was 357.4 ng/dL.

Effective combinatorial immunotherapy for penile squamous cell carcinoma

Penile squamous cell carcinoma (PSCC) accounts for over 95% of penile malignancies and causes significant mortality and morbidity in developing countries. Molecular mechanisms and therapies of PSCC are understudied, owing to scarcity of laboratory models. Herein, we describe a genetically engineered mouse model of PSCC, by co-deletion of Smad4 and Apc in the androgen-responsive epithelium of the penis. Mouse PSCC fosters an immunosuppressive microenvironment with myeloid-derived suppressor cells (MDSCs) as a dominant population. Preclinical trials in the model demonstrate synergistic efficacy of immune checkpoint blockade with the MDSC-diminishing drugs cabozantinib or celecoxib. A critical clinical problem of PSCC is chemoresistance to cisplatin, which is induced by Pten deficiency on the backdrop of Smad4/Apc co-deletion. Drug screen studies informed by targeted proteomics identify a few potential therapeutic strategies for PSCC. Our studies have established what we believe to be essential resources for studying PSCC biology and developing therapeutic strategies.

Androgen receptor expression in preputial dartos tissue correlates with physiological androgen exposure in congenital malformations of the penis and in controls

INTRODUCTION

The androgen receptor (AR) plays an important role in the development of male genitalia, and impaired androgen signalling has been hypothesised to underlie congenital penile malformations (CPM) such as hypospadias. Previous studies exploring the role of AR expression in the development of CPM have yielded conflicting results.

OBJECTIVES

To assess AR expression in human foreskin of boys/men born with hypospadias, buried penis versus controls.

STUDY DESIGN

Foreskin samples of 428 boys and men undergoing primary penile surgery (198 controls, 197 hypospadias, and 33 buried penis) were collected between October 2013 and July 2018. AR staining was performed in all samples and semi-quantitatively scored by two researchers independently, using a modified quick score (mQuicks) that assesses the proportion and intensity of AR staining in smooth muscle fibres.

RESULTS

The interobserver variability of the mQuicks had a high level of agreement for the total score, as well as for the subscores. Two phases of high AR expression were observed in all groups, the first following the postnatal gonadotropin surge (i.e., mini-puberty) and the second in (pre-) puberty. No differences in AR expression were found in hypospadias or buried penis cases as compared to controls matched for age at time of surgery.

DISCUSSION

This study describes the physiological evolution in AR expression in the human foreskin of boys with CPM and explains the cause of the previously reported, conflicting results. Despite the very large cohort, the limitations of this study are the low number of cases younger than six months at the time of surgery and the lack of Tanner stages to correlate with the mQuicks in adolescents.

CONCLUSIONS

The mQuicks is a straightforward and informative tool to semi-quantitatively assess AR expression in the dartos tissue. In this study, AR expression in human foreskin shows a bimodal distribution in boys with CMP and controls, following physiological androgen exposure. No statistically significant difference in AR expression could be found between both groups. Whether other local mechanisms are affected by these physiological changes is currently unclear. However, strict age-matching should be considered when exploring the mechanisms underlying disturbed penile and urethral development in CMP.

Prenatal bisphenol a and phthalate exposure are risk factors for male reproductive system development and cord blood sex hormone levels

Bisphenol A (BPA) and phthalates can adversely affect the fetal development. However, observational studies on the effects of these chemicals on fetal male reproductive system are still limited. A hundred of umbilical cord blood samples were analyzed for the levels of BPA, di-2-ethylhexyl phthalate (DEHP), mono-2-ethylhexyl phthalate (MEHP), and sex hormones. After birth, male newborns underwent physical examination that included measurements of anogenital distance, stretched penile length (SPL), and penile width. BPA, DEHP and MEHP levels were detectable in ≈99% of cord blood samples. In covariate-adjusted models, cord blood BPA levels were inversely associated with SPL of newborns and positively associated with cord blood estradiol levels. In addition, there was a significant inverse relationship between cord blood DEHP levels and anogenital distance index of newborn males. Our results suggest that in utero BPA and DEHP exposure exerted adverse effects on fetal male reproductive development and cord blood estradiol levels.

The human genital tubercle is steroidogenic organ at early pregnancy

It is generally accepted that androgens produced by fetal Leydig cells (FLC) control proper masculinization of the male external genitalia. Here, we hypothesized that the human genital tubercle (GT) has potential to synthesize androgens independently of FLC at early pregnancy. We observed that human GT of both genders have capacity to synthesize steroids of the Δ⁴, Δ⁵ and alternative pathway of DHT synthesis including the androgen itself. The presence of steroids in the GT was associated with the expression of corresponding steroidogenic enzymes. Levels of steroids and the expression of steroidogenic enzymes were similar in the GT from male and female fetuses. In contrast to the GT, the human fetal testis synthesized DHT from testosterone but not via the alternative pathway. Our findings strongly suggest that the human GT at early pregnancy can synthesize DHT via the alternative pathway, which may play an important role in organogenesis of the urethra.

Molecular genetics of hypospadias and cryptorchidism recent developments

During the last decade, a tremendous amount of work has been devoted to the study of the molecular genetics of isolated hypospadias and cryptorchidism, two minor forms of disorders of sex development (DSD). Beyond the genes involved in gonadal determination and sex differentiation, including those underlying androgen biosynthesis and signaling, new genes have been identified through genome-wide association study and familial clustering. Even if no single genetic defect can explain the whole spectrum of DSD, these recent studies reinforce the strong role of the genetic background in the occurrence of these defects. The timing of signaling disruption may explain the different phenotypes.

Expression of androgen, estrogen, and progesterone hormone receptors in the penile tissues of children with different types of hypospadias

OBJECTIVE:

Androgen (AR), Estrogen (ER) and Progesterone (PR) hormones play an important role in the prenatal and postnatal development of urogenital tract and especially the penis. The expressions of AR, ER and PR receptors in penile tissues in children with hypospadiases had also been shown previously. In this leading study, to demonstrate of the sex hormone receptor expression in cases with different types of hypospadias were aimed.

METHODS:

This study was designed in children operated due to hypospadiases without DSD. Biopsy samples of 3 mm’s were obtained from three different sytes as the lateral parameatal tissue and the anterior corner of the prepuce, and inner layer of posterior prepuce. The presence of AR, ER and PR receptors was investigated immunehistochemically.

RESULTS:

Mean age was 5.4 years in 18 children with hypospadiases; in totally 33 specimens were taken in 5 subcoronal as 5 specimens, and 7 penile as 15 specimens, and 6 penoscrotal as 13 specimens. According to sytes of samples; 13 samples were from lateral para-meatal tissues, and 13 were from anterior corners of prepuces, and 7 were from inner layers of posterior prepuces. In regard to receptor expression; ER and AR receptors were positive in 29 (87.8%) and 12 (36.4%) respectively; PR receptors were negative.

CONCLUSION:

This study emphasized the dominant expression of estrogen receptors in penile tissues of children with hypospadias. Although there was not a manifest correlation of androgen receptors absence in regard to the severity of hypospadias patients, there was a marked estrogen receptors presence in penile tissues. These findings suggest that the disrupted androgen and estrogen receptor interaction and/or balance could play a role during the development of external genitalia in hypospadias patients. Progesterone receptor was not present and therefore the active role in the postnatal development of hypospadias is still debatable.

The genetic factors contributing to hypospadias and their clinical utility in its diagnosis

Hypospadias is among the most common congenital malformations in male neonates. It results from abnormal penile and urethral development, but is a multifactorial disorder that is highly heterogeneous, with several genetic and environmental determinants. Monogenic and chromosomal abnormalities are present in approximately 30% of cases, although the genetic factors contributing to hypospadias remain unknown in 70% of cases. While defects in androgen synthesis can lead to this malformation, mutational analyses have shown several genes, such as sonic hedgehog, fibroblast growth factors, bone morphogenetic proteins, homeobox genes, and the Wnt family, are involved in the normal development of male external genitalia. Mutations in the genes of penile development (e.g., HOX, FGF, Shh) and testicular determination (e.g., WT1, SRY), luteinizing hormone receptor, and androgen receptor have also been proposed to be implicated in hypospadias. Here we review the recent advances in this field and discuss the potential genes that could determine the risk of hypospadias.

Immunohistochemical expression analysis of the human fetal lower urogenital tract

We have studied the ontogeny of the developing human male and female urogenital tracts from 9 weeks (indifferent stage) to 16 weeks (advanced sex differentiation) of gestation by immunohistochemistry on mid-sagittal sections. Sixteen human fetal pelvises were serial sectioned in the sagittal plane and stained with antibodies to epithelial, muscle, nerve, proliferation and hormone receptor markers. Key findings are: (1) The corpus cavernosum in males and females extends into the glans penis and clitoris, respectively, during the ambisexual stage (9 weeks) and thus appears to be an androgen-independent event. (2) The entire human male (and female) urethra is endodermal in origin based on the presence of FOXA1, KRT 7, uroplakin, and the absence of KRT10 staining. The endoderm of the urethra interfaces with ectodermal epidermis at the site of the urethral meatus. (3) The surface epithelium of the verumontanum is endodermal in origin (FOXA1-positive) with a possible contribution of Pax2-positive epithelial cells implying additional input from the Wolffian duct epithelium. (4) Prostatic ducts arise from the endodermal (FOXA1-positive) urogenital sinus epithelium near the verumontanum. (5) Immunohistochemical staining of mid-sagittal and para-sagittal sections revealed the external anal sphincter, levator ani, bulbospongiosus muscle and the anatomic relationships between these developing skeletal muscles and organs of the male and female reproductive tracts. Future studies of normal human developmental anatomy will lay the foundation for understanding congenital anomalies of the lower urogenital tract.

Development of the human penis and clitoris

The human penis and clitoris develop from the ambisexual genital tubercle. To compare and contrast the development of human penis and clitoris, we used macroscopic photography, optical projection tomography, light sheet microscopy, scanning electron microscopy, histology and immunohistochemistry. The human genital tubercle differentiates into a penis under the influence of androgens forming a tubular urethra that develops by canalization of the urethral plate to form a wide diamond-shaped urethral groove (opening zipper) whose edges (urethral folds) fuse in the midline (closing zipper). In contrast, in females, without the influence of androgens, the vestibular plate (homologue of the urethral plate) undergoes canalization to form a wide vestibular groove whose edges (vestibular folds) remain unfused, ultimately forming the labia minora defining the vaginal vestibule. The neurovascular anatomy is similar in both the developing human penis and clitoris and is the key to successful surgical reconstructions.

Expression of Xenobiotic Biomarkers CYP1 Family in Preputial Tissue of Patients with Hypospadias and Phimosis and Its Association with DNA Methylation Level of SRD5A2 Minimal Promoter

Several epidemiological studies have suggested that the incidence of male reproductive organ malformations, including hypospadias or cryptorchidism, has increased due to fetal-stage exposure to environmental pollutants. However, the association of chemical exposure with the expression of target regulatory genes in the tissues of patients has not yet been reported. Because experimental approaches or clinical trials in human studies are limited, especially those using fetal and/or infants, it is difficult to obtain clear physiological evidence of mechanisms underlying male reproductive malformations. Thus, the lack of physiological evidence makes this issue controversial. We analyzed preputial tissues from patients with hypospadias (n = 23) and phimosis (n = 16). The atypical CYP1 family genes, CYP1A1 and CYP1B1, are potential biomarkers of environmental chemical exposure. We then compared the expression levels of CYP1A1 and CYP1B1 between hypospadias and phimosis samples by quantitative RT-PCR analysis. The mRNA expression levels of SRD5A2 and AR also were measured, because the androgen-related genes involved in the onset of disorders of male reproductive system. A significantly higher CYP1B1 expression level and a lower AR expression level were observed in the hypospadias groups than in the phimosis group. Positive correlations (P < 0.001) between the mRNA expression levels of the CYP1 family and SRD5A2 were found in patients with hypospadias but not in those with phimosis. Moreover, the methylation levels of the four genes were determined by bisulfite genomic sequencing. Although the SRD5A2 promoter region showed moderate methylation, no methylation was detected in CYP1A1, CYP1B1, or AR. There was no significant difference in SRD5A2 promoter methylation level between hypospadias and phimosis patients. Negative correlations were found between the methylation level of SRD5A2, especially at the - 221 Sp1 site, and the CYP1 family mRNA expression levels (CYP1A1, p = 0.002; CYP1B1, p = 0.007) in hypospadias patients, but not in phimosis patients. The significant positive association of mRNA expression level and the negative association of methylation level of the SRD5A2 gene with the mRNA expression levels of CYP1 family genes in the preputial tissue seem to indicate the chemical exposure of patients with hypospadias.

A Single Nucleotide Variant in the Promoter Region of 17β-HSD Type 5 Gene Influences External Genitalia Virilization in Females with 21-Hydroxylase Deficiency

BACKGROUND

In 21-hydroxylase deficiency (21-OHD), there is an influence of genotype on the severity of external genitalia virilization. However, females carrying mutations predicting a similar impairment of enzymatic activity present a wide variability of genital phenotypes. In such cases, interindividual variability in genes related to the sex steroid hormone pathway could play a role.

OBJECTIVE

To evaluate the influence of POR, HSD17B5 and SRD5A2 variants on the severity of external genitalia virilization in 21-OHD females.

DESIGN AND PATIENTS

Prader stages were evaluated in 178 females with 21-OHD from a multicenter study. The 21-OHD genotypes were divided into two groups according to their severity: severe and moderate. The influences of the POR p.A503V, HSD17B5 c.-71A>G, HSD17B5 c.-210A>C, and SRD5A2 p.A49T and p.V89L variants on the degree of external genitalia virilization were analyzed.

RESULTS

The POR p.A503V, HSD17B5 c.-71A>G, HSD17B5 c.-210A>C, and SRD5A2 p.A49T and p.V89L variants were found in 25, 33, 17, 1, and 31% of the alleles, respectively. In uni- and multilinear regression, HSD17B5 c.-210A>C has a significant influence on the degree of external genitalia virilization. This variant was also identified with a higher frequency in the most severely virilized females.

CONCLUSION

We demonstrated that a variant in the promoter region of HSD17B5 related to fetal androgen synthesis influences the genital phenotype in 21-OHD females.

Association of SRD5A2 gene mutations with risk of hypospadias in the Iranian population

BACKGROUND

Hypospadias is one of the most common forms of congenital malformation of the male external genitalia worldwide. The ratio in the Iranian population is one in 250 live male births. The conversion of testosterone to dihydrotestosterone (DHT) in the presence of steroid 5α-reductase 2, which is encoded by SRD5A2 gene, plays an important role in the normal development of the male reproductive system.

METHODS

We examined whether SRD5A2 gene mutations (V89L and A49T polymorphisms) are associated with the risk of hypospadias in the Iranian population. We performed exons sequencing for SRD5A2 gene in 109 hypospadias patients.

RESULTS

We identified two new mutations in the subgroups of affected cases: including a substitution of the nucleotide T > A in the codon 73 [c.219T > A (p.Leu73_Ser74insHisPro)] and an insertion of an extra A nucleotide in the codon 77 [c.229insA* (p.Gly77*)]. Additionally, we performed PCR-RFLP for the two identified polymorphisms and revealed that V89L [OR = 5.8, 95% CI (3.8-8.8), p value < 0.001] and A49T [OR = 10.16, 95% CI (3.94-26.25), p value < 0.001] are significantly associated with hypospadias occurrence in patients. Our haplotype analysis further indicated that the Leu-Ala haplotype increases risk of hypospadias; conversely, the Val-Ala haplotype decreases the risk of hypospadias in the studied patients.

CONCLUSIONS

This study demonstrates that polymorphisms in the SRD5A2 gene could be considered as a risk factor for hypospadias disease emergence.

Systematic Review to Compare Urothelium Differentiation with Urethral Epithelium Differentiation in Fetal Development, as a Basis for Tissue Engineering of the Male Urethra

BACKGROUND

Tissue-engineered (TE) urethra is desirable in men with urethral disease (stricture or hypospadias) and shortage of local tissue. Although ideally a TE graft would contain urethral epithelium cells, currently, bladder epithelium (urothelium) is widely used, but morphologically different. Understanding the differences and similarities of urothelium and urethral epithelium could help design a protocol for in vitro generation of urethral epithelium to be used in TE grafts for the urethra.

PURPOSE

To understand the development toward urethral epithelium or urothelium to improve TE of the urethra.

METHODS

A literature search was done following PRISMA guidelines. Articles describing urethral epithelium and bladder urothelium development in laboratory animals and humans were selected.

RESULTS

Twenty-nine studies on development of urethral epithelium and 29 studies on development of urothelium were included. Both tissue linings derive from endoderm and although adult urothelium and urethral epithelium are characterized by different gene expression profiles, the signaling pathways underlying their development are similar, including Shh, BMP, Wnt, and FGF. The progenitor of the urothelium and the urethral epithelium is the early fetal urogenital sinus (UGS). The urethral plate and the urothelium are both formed from the p63+ cells of the UGS. Keratin 20 and uroplakins are exclusively expressed in urothelium, not in the urethral epithelium. Further research has to be done on unique markers for the urethral epithelium.

CONCLUSION

This review has summarized the current knowledge about embryonic development of urothelium versus urethral epithelium and especially focuses on the influencing factors that are potentially specific for the eventual morphological differences of both cell linings, to be a basis for developmental or tissue engineering of urethral tissue.

Ancestral androgenic differentiation pathways are repurposed during the evolution of adult sexual plasticity

Although early exposure to androgens is necessary to permanently organize male phenotype in many vertebrates, animals that exhibit adult sexual plasticity require mechanisms that prevent early fixation of genital morphology and allow for genital morphogenesis during adult transformation. In Lythrypnus dalli, a teleost fish that exhibits bi-directional sex change, adults display dimorphic genitalia morphology despite the absence of sex differences in the potent fish androgen 11-ketotestosterone. Based on conserved patterns of vertebrate development, two steroid-based mechanisms may regulate the early development and adult maintenance of dimorphic genitalia; local androgen receptor (AR) and steroidogenic enzyme expression. Consistent with the ancestral pattern of AR expression during the multipotential phase of differentiation, juvenile differentiation into either sex involved high mesenchymal AR expression. In adults, AR expression was high throughout the male genitalia, but low or absent in females. Consistent with the hypothesis that adult sexual plasticity repurposes pathways from primary differentiation, we show that adults with transitioning genitalia also exhibited higher AR expression relative to females. Local androgen biosynthesis may also participate in genitalia transformation, as transitioning adults had greater 11β-HSD-like immunoreactivity in the epithelial layer of the dorsal lumen compared to both sexes. By administering an AR antagonist to adult males, we show AR is necessary to maintain male-typical morphology. In a species that is resistant to early sexual canalization, early androgenic differentiation mechanisms are consistent with other vertebrates and the tissue-specific regulation of AR expression appears to be repurposed in adulthood to allow for transitions between sexual phenotypes.

Immunohistochemistry Study on Androgen and Estrogen Receptors of Rat Seminal Vesicle Submitted to Simultaneous Alcohol-Nicotine Treatment

Objective

Alcohol consumption is habitually accompanied by the use of other psychoactive substances, mostly tobacco. Nicotine and alcohol affect male accessory reproductive glands function. Most studies have been done on pathologic features of prostate, but there has been no systematic study on the seminal vesicle. Therefore, the aim of current study was to investigate the distribution of androgen receptor (AR) and estrogen receptors-beta (ER-β) immune reactivities following long-term treatment of alcohol, nicotine or a combination of both substances.

Materials and Methods

In this experimental study, a total of 40 adult Wistar rats, nine weeks of age, were used. Animals were randomly divided into four groups, including: i. Control group receiving normal saline 0.09%, ii. Ethanol group receiving ethanol 20% (2 ml/kg, via gavage), iii. Nicotine group receiving nicotine (0.1 mg/kg, subcutaneous injection), and iv. Ethanol-nicotine group receiving simultaneous ethanol 20% (2 ml/kg) and nicotine (0.1 mg/kg) treatment. All treatment lasted for eight weeks. Prior to intracardiac perfusion, blood sample was collected from left ventricle. The seminal vesicles were isolated and processed for paraffin blocking. The sample tissues were then studied for distribution of AR and ER-β immunereactivities using immunohistochemical (IHC) staining method. One way analysis of variance (ANOVA) and Tukey’s test were performed for data analysis. A value of P<0.05 was considered significant.

Results

Our results revealed that the lowest mean number of positive cells belonged to the animals of ethanol-nicotine group that was followed by the ethanol, nicotine, and control groups, respectively. However, there was no significant difference regarding serum testosterone level among experimental groups.

Conclusion

It was concluded that combination of both ethanol and nicotine may be a crucial factor in the expression levels of AR and ER-β.

Challenges in Testosterone Measurement, Data Interpretation, and Methodological Appraisal of Interventional Trials

INTRODUCTION

Male hypogonadism is a common condition, with an increasing body of literature on diagnosis, implications, and management. Given the significant variability in testosterone (T) from a physiologic and assay perspective, a thorough understanding of factors affecting T values and study methodology is essential to interpret reported study outcomes appropriately. However, despite the large number of publications on T, there are no reference materials consolidating all relevant and potentially confounding factors necessary to interpret T studies appropriately.

AIMS

To create a resource document that reviews sources of T variability, free vs total T, assay techniques and questionnaires, and study methodology relevant to interpreting outcomes.

METHODS

A PubMed search was performed of all the T literature published on T variability, assay techniques, and T-specific questionnaires. Results were summarized in the context of their impact on interpreting T literature outcomes and methodology.

MAIN OUTCOME MEASURES

Effect of various factors on T variability and their relevance to study methodology and outcomes.

RESULTS

Several factors affect measured T levels, including aging, circadian rhythms, geography, genetics, lifestyle choices, comorbid conditions, and intraindividual daily variability. The utility of free T over total T is debatable and must be compared using appropriate threshold levels. Among various assay techniques, mass spectrometry and equilibrium dialysis are gold standards. Calculated empirical estimates of free T also are commonly used and accepted. Hypogonadism-specific questionnaires have limited utility in screening for hypogonadism, and their role as objective end points for quantifying symptoms remains unclear. Numerous aspects of study methodology can directly or indirectly affect reported outcomes, including design (randomized, prospective, retrospective), duration, populations studied (age, comorbid conditions), low T threshold, therapeutic agent used, objective measurements and end points selected, and statistical interpretation.

CONCLUSION

Critical appraisal of the T literature requires an understanding of numerous factors resulting in T variability, study design and methodology, and limitations of assay techniques and objective measurement scales.

Perineal raphe with special reference to its extension to the anus: a histological study using human fetuses

The raphe of the human penis and scrotum is considered to develop secondarily after disappearance of the initial midline seam by fusion of the bilateral genital folds. However, the fetal development was still obscure. We examined histological sections of 30 fetuses (17 males and 13 females) at 10–15 weeks. In male fetuses, the scrotum was not yet clearly identified because of no descent of testis. The perineal raphe was thin and wavy at 10 weeks, and it was continuous with and took a direction same as the inferior wall of the closed penile urethra after physiological hypospadias. Depending on growth of the bulbospongiosus muscle and corpus spongiosus penis, the midline intermuscular septum obtained a connection to the subcutaneous wavy raphe and made the latter thick and straight at 12–15 weeks. Notably, the perineal raphe extended posteriorly to attach to the external anal sphincter. In female fetuses, an epithelial fusion occurred along a short distance at the posterior end of the vestibule. However, in front of the external anal sphincter, a large midline mesenchymal tissue from the urorectal septum did not contain a raphe-like structure. Moreover, since the bilateral bulbospongiosus muscles were separated widely by the vestibule, they did not provide a midline septum. Fetal development of the perineal raphe was accelerated by reinforcement from the muscular septum. In contrast, without such a muscular support, the female raphe could not maintain its growth even if the seed appeared at the posterior end of the vestibule.

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.

Side Effects of 5-Alpha Reductase Inhibitors: A Comprehensive Review

INTRODUCTION

5α-reductase inhibitors (5ARI) include finasteride and dutasteride, and are commonly prescribed in the treatment of benign prostatic hyperplasia and androgenic alopecia. 5ARIs are associated with several known adverse effects (AEs), with varying reported prevalence rates.

AIM

The aim was to review and summarize findings from published literature detailing AEs associated with 5ARI use. A secondary aim was to review potential mechanisms of action, which may account for these observed and reported AEs.

METHODS

A PubMed search was conducted on articles published from 1992 to 2012, which reported AEs with 5ARIs. Priority was given to randomized, placebo-controlled trials. Studies investigating potential mechanisms of action for 5ARIs were included for review.

MAIN OUTCOME MEASURES

AE data reported from available trials were summarized and reviewed.

RESULTS

Reported AEs with 5ARIs include sexual dysfunction, infertility, mood disorders, gynecomastia, high-grade prostate cancer, breast cancer, and cardiovascular morbidity/risk factors, although their true association, prevalence, causality, and clinical significance remain unclear. A pooled summary of all randomized, placebo-controlled trials evaluating 5ARIs (N = 62,827) revealed slightly increased rates over placebo for decreased libido (1.5%), erectile dysfunction (ED) (1.6%), ejaculatory dysfunction (EjD) (3.4%), and gynecomastia (1.3%). The limited data available on the impact of 5ARIs on mood disorders demonstrate statistically significant (although clinically minimal) differences in rates of depression and/or anxiety. Similarly, there are limited reports of reversible, diminished fertility among susceptible individuals. Post-marketing surveillance reports have questioned the actual prevalence of AEs associated with 5ARI use and suggest the possibility of persistent symptoms after drug discontinuation. Well-designed studies evaluating these reports are needed.

CONCLUSIONS

5ARIs are associated with slightly increased rates of decreased libido, ED, EjD, gynecomastia, depression, and/or anxiety. Further studies directed at identifying prevalence rates and persistence of symptoms beyond drug discontinuation are required to assess causality. Trost L, Saitz TR, and Hellstrom WJG. Side effects of 5-alpha reductase inhibitors: A comprehensive review. Sex Med Rev 2013;1:24-41.

Bulbocavernosus muscle area measurement: a novel method to assess androgenic activity

Serum testosterone does not correlate with androgen tissue activity, and it is critical to optimize tools to evaluate such activity in males. Ultrasound measurement of bulbocavernosus muscle (BCM) was used to assess the relationship between the number of CAG repeats (CAGn) in the androgen receptor (AR) and the BCM size; the changes in the number of CAGn over age were also evaluated. Transperineal ultrasound measurement of the BCM was also performed. AR CAGn were determined by high performance liquid chromatography, and morning hormone levels were determined using immunoassays. Forty-eight men had CAG repeat analysis. Twenty-five were <30 years of age, mean 23.7 years (s.d. = 3.24) and 23 were >45 years of age, mean 53 years (s.d. = 5.58). The median CAGn was 21 (13-29). BCM area was greater when the number of CAGn were <18 as compared to the number of CAGn >24 (P = 0.04). There was a linear correlation between the number of CAGn and the BCM area R 2 = 16% (P = 0.01). In the 45 to 65-years-old group, a much stronger negative correlation (R 2 = 29%, P = 0.01) was noticed. In the 19 to 29-years-old group, no such correlation was found (R 2 = 4%, P = 0.36). In older men, the number of CAGn increased with age (R 2 = 32%, P = 0.01). The number of CAGn in the AR correlates with the area of the BCM. Ultrasound assessment of the BCM is an effective surrogate to evaluate end-organ activity of androgens. The number of CAGn may increase with age.

Determinants of Receptor- and Tissue-Specific Actions in Androgen Signaling

The physiological androgens testosterone and 5α-dihydrotestosterone regulate the development and maintenance of primary and secondary male sexual characteristics through binding to the androgen receptor (AR), a ligand-dependent transcription factor. In addition, a number of nonreproductive tissues of both genders are subject to androgen regulation. AR is also a central target in the treatment of prostate cancer. A large number of studies over the last decade have characterized many regulatory aspects of the AR pathway, such as androgen-dependent transcription programs, AR cistromes, and coregulatory proteins, mostly in cultured cells of prostate cancer origin. Moreover, recent work has revealed the presence of pioneer/licensing factors and chromatin modifications that are important to guide receptor recruitment onto appropriate chromatin loci in cell lines and in tissues under physiological conditions. Despite these advances, current knowledge related to the mechanisms responsible for receptor- and tissue-specific actions of androgens is still relatively limited. Here, we review topics that pertain to these specificity issues at different levels, both in cultured cells and tissues in vivo, with a particular emphasis on the nature of the steroid, the response element sequence, the AR cistromes, pioneer/licensing factors, and coregulatory proteins. We conclude that liganded AR and its DNA-response elements are required but are not sufficient for establishment of tissue-specific transcription programs in vivo, and that AR-selective actions over other steroid receptors rely on relaxed rather than increased stringency of cis-elements on chromatin.

Canalization of the urethral plate precedes fusion of the urethral folds during male penile urethral development: the double zipper hypothesis

PURPOSE

We describe the "double zipper" mechanism of human male urethral formation, where the distal zipper opens the urethral groove through canalization of the urethral plate, and a second closing zipper follows behind and closes the urethral groove to form the tubular urethra.

MATERIALS AND METHODS

Anonymous human fetal genital specimens were acquired and gender was determined by polymerase chain reaction of the Y chromosome. Specimens were processed for optical projection tomography, stained with E-cadherin, Ki67 and caspase 3, and imaged.

RESULTS

Eight developing male fetal specimens from 6.5 to 16.5 weeks of gestation were analyzed by optical projection tomography, and an additional 5 specimens by serial sections. Phallus length ranged from 1.3 to 3.7 mm. The urethral plate canalized into a groove with 2 epithelial edges that subsequently fused. Ki67 staining was localized to the dorsal aspect of the urethral plate. In contrast, caspase 3 staining was not observed. The entire process was completed during a 10-week period.

CONCLUSIONS

The human male urethra appears to form by 2 mechanisms, an initial "opening zipper" that facilitates distal canalization of the solid urethral plate to form the urethral groove, which involves a high rate of epithelial proliferation (apoptosis not observed), and a "closing zipper" facilitating fusion of the 2 epithelial surfaces of the urethral groove, and thus extending the penile urethra distally. Improved knowledge of the molecular mechanisms of these processes is critical to understanding mechanisms of abnormal urethral development, such as hypospadias.

Penile length, digit length, and anogenital distance according to birth weight in newborn male infants

PURPOSE

Anogential distance (AGD) and the 2:4 digit length ratio appear to provide a reliable guide to fetal androgen exposure. We intended to investigate the current status of penile size and the relationship between penile length and AGD or digit length according to birth weight in Korean newborn infants.

MATERIALS AND METHODS

Between May 2013 and February 2014, among a total of 78 newborn male infants, 55 infants were prospectively included in this study. Newborn male infants with a gestational age of 38 to 42 weeks and birth weight>2.5 kg were assigned to the NW group (n=24) and those with a gestational age<38 weeks and birth weight<2.5 kg were assigned to the LW group (n=31). Penile size and other variables were compared between the two groups.

RESULTS

Stretched penile length of the NW group was 3.3 ± 0.2 cm, which did not differ significantly from that reported in 1987. All parameters including height, weight, penile length, testicular size, AGD, and digit length were significantly lower in the LW group than in the NW group. However, there were no significant differences in AGD ratio or 2:4 digit length ratio between the two groups.

CONCLUSIONS

The penile length of newborn infants has not changed over the last quarter century in Korea. With normal penile appearance, the AGD ratio and 2:4 digit length ratio are consistent irrespective of birth weight, whereas AGD, digit length, and penile length are significantly smaller in newborns with low birth weight.

Sexually dimorphic expression of Mafb regulates masculinization of the embryonic urethral formation

Masculinization of external genitalia is an essential process in the formation of the male reproductive system. Prominent characteristics of this masculinization are the organ size and the sexual differentiation of the urethra. Although androgen is a pivotal inducer of the masculinization, the regulatory mechanism under the control of androgen is still unknown. Here, we address this longstanding question about how androgen induces masculinization of the embryonic external genitalia through the identification of the v-maf avian musculoaponeurotic fibrosarcoma oncogene homolog B (Mafb) gene. Mafb is expressed prominently in the mesenchyme of male genital tubercle (GT), the anlage of external genitalia. MAFB expression is rarely detected in the mesenchyme of female GTs. However, exposure to exogenous androgen induces its mesenchymal expression in female GTs. Furthermore, MAFB expression is prominently down-regulated in male GTs of androgen receptor (Ar) KO mice, indicating that AR signaling is necessary for its expression. It is revealed that Mafb KO male GTs exhibit defective embryonic urethral formation, giving insight into the common human congenital anomaly hypospadias. However, the size of Mafb KO male GTs is similar with that of wild-type males. Moreover, androgen treatment fails to induce urethral masculinization of the GTs in Mafb KO mice. The current results provide evidence that Mafb is an androgen-inducible, sexually dimorphic regulator of embryonic urethral masculinization.

The power and perils of animal models with urogenital anomalies: handle with care

Congenital abnormalities of the urogenital tracts form a major part of clinical practice for paediatric urologists, but their knowledge of normal and abnormal development is often limited. Advances in understanding frequently come from studying experimental findings from animal models, however, most clinicians underestimate both the power and perils of extrapolating scientific knowledge from animals. In this review, the key issues that urologists need to understand in order to link animal studies to clinical practice are discussed. Urologists must avoid the traps of anthropomorphism (assuming humans are always the same as animal models) or anthropocentrism (assuming humans are too different from animal models). This review used two common disorders: hypospadias and undescended testes.

Androgens and mammalian male reproductive tract development

One of the main functions of androgen is in the sexually dimorphic development of the male reproductive tissues. During embryogenesis, androgen determines the morphogenesis of male specific organs, such as the epididymis, seminal vesicle, prostate and penis. Despite the critical function of androgens in masculinization, the downstream molecular mechanisms of androgen signaling are poorly understood. Tissue recombination experiments and tissue specific androgen receptor (AR) knockout mouse studies have revealed epithelial or mesenchymal specific androgen-AR signaling functions. These findings also indicate that epithelial-mesenchymal interactions are a key feature of AR specific activity, and paracrine growth factor action may mediate some of the effects of androgens. This review focuses on mouse models showing the interactions of androgen and growth factor pathways that promote the sexual differentiation of reproductive organs. Recent studies investigating context dependent AR target genes are also discussed. This article is part of a Special Issue entitled: Nuclear receptors in animal development.

Seasonal variation of urinary microRNA expression in male goats (Capra hircus) as assessed by next generation sequencing

Testosterone plays a key role in preparation of a male domesticated goat (Capra hircus) to breeding season including changes in the urogenital tract of a male goat (buck). microRNAs are important regulators of cellular metabolism, differentiation and function. They are powerful intermediaries of hormonal activity in the body, including the urogenital tract. We investigated seasonal changes in expression of microRNAs in goat buck urine and their potential consequences using next generation sequencing (microRNA-Seq). We determined the location of each microRNA gene in the goat genome. Testosterone was measured by radioimmunoassay and the androgen receptor binding sites (ARBS) in the promoters of the microRNA genes were determined by MatInspector. The overall impact of regulated microRNAs on cellular physiology was assessed by mirPath. We observed high testosterone levels during the breeding season and changes in the expression of forty microRNAs. Nineteen microRNAs were upregulated, while twenty-one were downregulated. We identified several ARBS in the promoters of regulated microRNAs. Notably, the mostly inhibited microRNA, miR-1246, has a unique set of several gene copy variants associated with a cluster of androgen receptor binding sites. Concomitant changes in regulated microRNA expression could promote transcription, proliferation and differentiation of urogenital tract cells. Together, these findings indicate that in a domesticated goat (Capra hircus), there are specific changes in the microRNA expression profile in buck urine during breeding season, which could be attributable to high testosterone levels during breeding, and could help in preparation of the urogenital tract for high metabolic demands of that season.

Low androgen induced penile maldevelopment involves altered gene expression of biomarkers of smooth muscle differentiation and a key enzyme regulating cavernous smooth muscle cell tone

PURPOSE

We determined the effects of low androgens in the neonatal period on biomarkers of smooth muscle cell differentiation, Myh11 and Acta2, and on Pde5A expression in the penis.

MATERIALS AND METHODS

One-day-old pups were treated daily with the gonadotropin-releasing hormone antagonist antide with or without dihydrotestosterone for 1 to 6 days. Tissues were collected at age day 7 and at adulthood at age 120 days. Penes were examined by quantitative reverse transcriptase-polymerase chain reaction, Western blot and immunohistochemistry. Testes were assayed for the intratesticular testosterone and steroidogenic enzymes Cyp17α1 and StAR.

RESULTS

Gonadotropin-releasing hormone antagonist exposure suppressed the neonatal testicular testosterone surge 70% to 80%. Quantitative reverse transcriptase-polymerase chain reaction revealed 80% to 90% reductions in Cyp17α1 and StAR protein, and 40% to 60% reductions in Myh11 and ACTA2 as a result of gonadotropin-releasing hormone antagonist compared to controls. Dihydrotestosterone co-administration mitigated these decreases. Western blot confirmed the Myh11 decrease at the protein level. Immunohistochemistry of Acta2 confirmed cavernous smooth muscle cell loss at the tissue level. Also, gonadotropin-releasing hormone antagonist exposure decreased Pde5a expression and dihydrotestosterone co-administration mitigated the decrease. Comparison of data between 2 parts of the penis body (corpora cavernosa and corpus spongiosum) showed that antagonist induced decreases in Myh11, Acta2 and Pde5a expression occurred only in the corpora cavernosa, implying that the latter is the target site of low androgen action.

CONCLUSIONS

As evidenced by gonadotropin-releasing hormone antagonist induced suppression of the neonatal testosterone surge and reduced steroidogenesis, low androgens in the neonatal period altered gene expression of biomarkers of smooth muscle cell differentiation. This led to loss of cavernous smooth muscle cells and consequently to penile maldevelopment.

Congenital absence of preputial foreskin: an extremely uncommon anomaly

The part of the penile skin that covers the glans penis is named prepuce or foreskin. The embryologic development of the prepuce and urethra is related. Several congenital anomalies of the prepuce have been previously reported, but the absence of the prepuce with a normal development of the urethra is a very rare association. We report a sporadic case with absence of the prepuce and normal urethral development.