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

MAFB-mediated CEBPA regulated human urothelium growth through Wnt/β-catenin signaling pathway

MAFB is essential for regulating male-type urethral differentiation, and especially, its variation can contribute to hypospadias in mice. However, the potential mechanism is still unclear. Here we observed that the basic leucine zipper (bZIP) transcription factor MAFB and CCAAT/enhancer-binding protein alpha (CEBPA) could promote human urothelium SV-HUC-1 growth. Moreover, MAFB and CEBPA expression were reduced in the prepuce tissues of hypospadias patients. Based on transcriptome sequencing analysis and Western blot, MAFB knockdown was found to suppress CEBPA protein expression and repress Wnt/β-catenin signaling in urothelium cells. Meanwhile, we observed blocked cell-cycle progression from the G1 to the S phase, inhibited cell proliferation, and activated apoptosis. Furthermore, MAFB could facilitate CEBPA transcription and regulate the proliferation of urothelium. The above results indicated that MAFB-mediated inhibition of urothelial SV-HUC-1 growth resulted from inhibiting the Wnt/β-catenin signaling pathway by down-regulating CEBPA. Our findings provide new insight into the understanding of genes associated with hypospadias and the pathogenic mechanism of this disorder.

Developmental and functional roles of androgen and interactive signals for external genitalia and erectile tissues

Background

Recent progress in molecular and signal analyses revealed essential functions of cellular signals including androgen and related growth factors such as Wnt regulators for external genitalia (ExG) development and its pathogenesis. Accumulated data showed their fundamental functions also for erectile tissue (corporal body) development and its abnormalities. The current review focuses on such signals from developmental and functional viewpoints.

Methods

Experimental strategies including histological and molecular signal analyses with conditional mutant mice for androgen and Wnt signals have been extensively utilized.

Main findings

Essential roles of androgen for the development of male-type ExG and urethral formation are shown. Wnt signals are associated with androgen for male-type ExG organogenesis. Androgen plays essential roles in the development of erectile tissue, the corporal body and it also regulates the duration time of erection. Wnt and other signals are essential for the regulation of mesenchymal cells of erectile tissue as shown by its conditional mutant mouse analyses. Stress signals, continuous erection, and the potential of lymphatic characteristics of the erectile vessels with sinusoids are also shown.

Conclusion

Reiterated involvement of androgen, Wnt, and other regulatory factors is stated for the development and pathogenesis of ExG and erectile tissues.

Novel erectile analyses revealed augmentable penile Lyve-1, the lymphatic marker, expression

Purpose

The pathophysiology of penis extends to erectile dysfunction (ED) to conditions including sexually transmitted diseases (STDs) and cancer. To date, there has been little research evaluating vascular drainage from the penis. We aimed to evaluate penile blood flow in vivo and analyze its possible relationship with the lymphatic maker.

Materials and Methods

We established an in vivo system designed to assess the dynamic blood outflow from the corpus cavernosum (CC) by dye injection. To analyze lymphatic characteristics in the CC, the expression of Lyve-1, the key lymphatic endothelium marker, was examined by the in vitro system and lipopolysaccharide (LPS) injection to mimic the inflammatory conditions.

Results

A novel cavernography methods enable high-resolution morphological and functional blood drainage analysis. The expression of Lyve-1 was detected along the sinusoids. Furthermore, its prominent expression was also observed after penile LPS injection and in the erectile condition.

Conclusions

The current in vivo system will potentially contribute to the assessment of penile pathology from a novel viewpoint. In addition, current analyses revealed inducible Lyve-1 expression for LPS injection and the erection state, which requires further analyses on penile lymphatic system.

hsa_circ_0000417 downregulation suppresses androgen receptor expression and apoptotic signals in human foreskin fibroblasts via sponging miR-6756-5p

BACKGROUND

Dysregulated apoptosis of penile mesenchymal cells during male urethragenesis has been previously demonstrated to underly hypospadiac urethral closure failure, and androgen receptor (AR) has been shown to play a central role in regulating penile mesenchyme cell proliferation and survival. However, the regulatory mechanisms upstream and downstream of AR remain poorly understood. Our clinical data and bioinformatics analysis previously indicated that hsa_circ_0000417, a circRNA significantly downregulated in hypospadias preputial specimens, may act as a ceRNA for AR via sequestering hsa_miR-6756-5p, and that the biological functions of hsa_circ_0000417 may significantly involve the PI3K/AKT pathway. In this study, we employed human foreskin fibroblasts (HFF-1) to experimentally validate this putative hsa_circ_0000417/miR-6756-5p/AR axis and its impact on penile mesenchymal cell proliferation and apoptosis.

METHOD AND RESULTS

We showed that hsa_circ_0000417 knockdown significantly promoted proliferation and suppressed apoptosis of HFF-1 cells. Mechanistically, hsa_circ_0000417 functioned as a molecular sponge for miR-6756-5p in HFF-1 cells and relieved the latter's translational repression on AR mRNA, leading to decreased AKT activation and increased expression of pro-apoptotic proteins BAX and cleaved-caspase 9. Conversely, elevated levels of miR-6756-5p resulted in diminished AR expression concomitant with enhanced AKT activation and HFF-1 cell proliferation.

CONCLUSIONS

Collectively, our data describe for the first time a circRNA-mediated post-transcriptional regulatory mechanism of AR and its functional consequences in penile mesenchymal cells in the context of hypospadias. These findings may contribute to advancing our current understanding of the roles of AR and mesenchymal cell fate decisions during penile morphogenesis.

Innovative Approaches and Advances for Hair Follicle Regeneration

Pathological hair loss (also known as alopecia) and shortage of hair follicle (HF) donors have posed an urgent requirement for HF regeneration. With the revelation of mechanisms in tissue engineering, the proliferation of HFs in vitro has achieved more promising trust for the treatments of alopecia and other skin impairments. Theoretically, HF organoids have great potential to develop into native HFs and attachments such as sweat glands after transplantation. However, since the rich extracellular matrix (ECM) deficiency, the induction characteristics of skin-derived cells gradually fade away along with their trichogenic capacity after continuous cell passaging in vitro. Therefore, ECM-mimicking support is an essential prelude before HF transplantation is implemented. This review summarizes the status of providing various epidermal and dermal cells with a three-dimensional (3D) scaffold to support the cell homeostasis and better mimic in vivo environments for the sake of HF regeneration. HF-relevant cells including dermal papilla cells (DPCs), hair follicle stem cells (HFSCs), and mesenchymal stem cells (MSCs) are able to be induced to form HF organoids in the vitro culture system. The niche microenvironment simulated by different forms of biomaterial scaffold can offer the cells a network of ordered growth environment to alleviate inductivity loss and promote the expression of functional proteins. The scaffolds often play the role of ECM substrates and bring about epithelial-mesenchymal interaction (EMI) through coculture to ensure the functional preservation of HF cells during in vitro passage. Functional HF organoids can be formed either before or after transplantation into the dermis layer. Here, we review and emphasize the importance of 3D culture in HF regeneration in vitro. Finally, the latest progress in treatment trials and critical analysis of the properties and benefits of different emerging biomaterials for HF regeneration along with the main challenges and prospects of HF regenerative approaches are discussed.

A visualization system for erectile vascular dynamics

Erection is an essential process which requires the male penis for copulation. This copulatory process depends on the vascular dynamic regulation of the penis. The corpus cavernosum (CC) in the upper (dorsal) part of the penis plays a major role in regulating blood flow inside the penis. When the CC is filled with blood, the sinusoids, including micro-vessels, dilate during erection. The CC is an androgen-dependent organ, and various genital abnormalities including erectile dysfunction (ED) are widely known. Previous studies have shown that androgen deprivation by castration results in significantly decreased smooth muscles of the CC. Experimental works in erectile biology have previously measured intracavernosal penile pressure and mechanical tension. Such reports analyze limited features without assessing the dynamic aspects of the erectile process. In the current study, we established a novel explant system enabling direct visual imaging of the sinusoidal lumen to evaluate the dynamic movement of the cavernous space. To analyze the alternation of sinusoidal spaces, micro-dissected CC explants by patent blue dye injection were incubated and examined for their structural alternations during relaxation/contraction. The dynamic process of relaxation/contraction was analyzed with various external factors administered to the CC. The system enabled the imaging of relaxation/contraction of the lumens of the sinusoids and the collagen-containing tissues. Histological analysis on the explant system also showed the relaxation/contraction. Thus, the system mimics the regulatory process of dynamic relaxation/contraction in the erectile response. The current system also enabled evaluating the erectile pathophysiology. In the current study, the lumen of sinusoids relaxed/contracted in castrated mice similarly with normal mice. These results suggested that the dynamic erectile relaxation/contraction process was similarly retained in castrated mice. However, the system also revealed decreased duration time of erection in castrated mice. The current study is expected to promote further understanding of the pathophysiology of ED, which will be useful for new treatments in the future. Hence, the current system provides unique information to investigate the novel regulations of erectile function, which can provide tools for analyzing the pathology of ED.

3D reconstruction and histopathological analyses on murine corporal body

PURPOSE

Erectile dysfunction (ED) is one of the increasing diseases with aging society. The basis of ED derived from local penile abnormality is poorly understood because of the complex three-dimensional (3D) distribution of sinusoids in corpus cavernosum (CC). Understanding the 3D histological structure of penis is thus necessary. Analyses on the status of regulatory signals for such abnormality are also performed.

METHODS

To analyze the 3D structure of sinusoid, 3D reconstruction from serial sections of murine CC were performed. Histological analyses between young (2 months old) and aged (14 months old) CC were performed. As for chondrogenic signaling status of aged CC, SOX9 and RBPJK staining was examined.

RESULTS

Sinusoids prominently developed in the outer regions of CC adjacent to tunica albuginea. Aged CC samples contained ectopic chondrocytes in such regions. Associating with the appearance of chondrocytes, the expression of SOX9, chondrogenic regulator, was upregulated. The expression of RBPJK, one of the Notch signal regulators, was downregulated in the aged CC.

CONCLUSIONS

Prominent sinusoids distribute in the outer region of CC which may possess important roles for erection. A possibility of ectopic chondrogenesis induced by alteration of SOX9/Notch signaling with aging is indicated.

Expression of Mafb is down-regulated in the foreskin of children with hypospadias

BACKGROUND

Hypospadias is the second most common congenital malformation in males. Although the aetiology of hypospadias is not clear, it is generally thought to be affected by both genetic and environmental endocrine-disrupting factors that affect the development of the urethra, leading to deformity.

OBJECTIVE

To investigate the difference in expression of the transcription factor Mafb in hypospadias and normal penile tissues and to assess whether it is related to the occurrence of hypospadias.

STUDY DESIGN

Penile tissue was obtained from children with hypospadias who underwent surgical repair at the Children's Hospital of Chongqing Medical University. Patients diagnosed with undescended testicles, intersex status or endocrine abnormalities were excluded from the study. Twenty-five cases with hypospadias (average 3.5 years old) and 15 cases with circumcisions (as control) (average 5 years old) were included in this study. Real-time quantitative polymerase chain reaction, Immunochemistry and Western blot were used to detect the expression of Mafb.

RESULTS

Mafb mRNA expressions in the prepuce of cases with hypospadias was significantly reduced compared with that in the controls [(1.179 ± 0.1275), (0.6652 ± 0.07506), p < 0.05)]. Hypospadias cases also showed decreased Mafb protein expression in the preputial subcutaneous mesenchymal cell layer. Mafb protein levels were significantly decreased in those with hypospadias compared with controls [(1.932 ± 0.1139), (1.006 ± 0.03312), p < 0.05]. However, no such differences were found in Mafb expression between subjects with mild and severe hypospadias.

DISCUSSION

Compared to the normal foreskin, expression of the Mafb gene was down-regulated at both mRNA and protein levels, which was consistent with our RNA-seq sequencing results in Diethylhexyl phthalate (DEHP)-induced hypospadias rats. This study is the first to report abnormal expression of Mafb in the preputial tissue of hypospadias cases. An in-depth study of the relationship between Mafb and cell proliferation, apoptosis, and urethra development may reveal the pathogenesis of hypospadias.

CONCLUSION

Expression of the Mafb gene and protein in the foreskin of children with hypospadias is lower than that in normal foreskin. We postulate that such abnormal expression of the Mafb gene may be related to the occurrence of hypospadias and that this abnormal expression may affect the development of the urethra during the embryonic period.

Hedgehog signal disruption, gonadal dysgenesis and reproductive disorders: Is there a link to endocrine disrupting chemicals?

Developmental exposure to chemicals that can disrupt sex hormone signaling may cause a broad spectrum of reproductive disorders. This is because reproductive development is tightly regulated by steroid sex hormones. Consequently, non-animal screening methods currently used to test chemicals for potential endocrine disrupting activities typically include steroidogenesis and nuclear receptor assays. In many cases there is a correlation between in vitro and in vivo data examining endocrine disruption, for example between blocked androgen receptor activity and feminized male genitals. However, there are many examples where there is poor, or no, correlation between in vitro data and in vivo effect outcomes in rodent studies, for various reasons. One possible, and less studied, reason for discordance between in vitro and in vivo data is that the mechanisms causing the in vivo effects are not covered by those typically tested for in vitro. This knowledge gap must be addressed if we are to elaborate robust testing strategies that do not rely on animal experimentation. In this review, we highlight the Hedgehog (HH) signaling pathway as a target for environmental chemicals and its potential implications for reproductive disorders originating from early life exposure. A central proposition is that, by disrupting HH signal transduction during critical stages of mammalian development, the endocrine cells of the testes or ovaries fail to develop normally, which ultimately will lead to disrupted sex hormone synthesis and sexual development in both sexes. If this is the case, then such mechanism must also be included in future test strategies aimed at eliminating chemicals that may cause reproductive disorders in humans.

Hormonal and Molecular Regulation of Phallus Differentiation in a Marsupial Tammar Wallaby

Congenital anomalies in phalluses caused by endocrine disruptors have gained a great deal of attention due to its annual increasing rate in males. However, the endocrine-driven molecular regulatory mechanism of abnormal phallus development is complex and remains largely unknown. Here, we review the direct effect of androgen and oestrogen on molecular regulation in phalluses using the marsupial tammar wallaby, whose phallus differentiation occurs after birth. We summarize and discuss the molecular mechanisms underlying phallus differentiation mediated by sonic hedgehog (SHH) at day 50 pp and phallus elongation mediated by insulin-like growth factor 1 (IGF1) and insulin-like growth factor binding protein 3 (IGFBP3), as well as multiple phallus-regulating genes expressed after day 50 pp. We also identify hormone-responsive long non-coding RNAs (lncRNAs) that are co-expressed with their neighboring coding genes. We show that the activation of SHH and IGF1, mediated by balanced androgen receptor (AR) and estrogen receptor 1 (ESR1) signalling, initiates a complex regulatory network in males to constrain the timing of phallus differentiation and to activate the downstream genes that maintain urethral closure and phallus elongation at later stages.

Hedgehog Signaling for Urogenital Organogenesis and Prostate Cancer: An Implication for the Epithelial-Mesenchyme Interaction (EMI)

Hedgehog (Hh) signaling is an essential growth factor signaling pathway especially in the regulation of epithelial-mesenchymal interactions (EMI) during the development of the urogenital organs such as the bladder and the external genitalia (EXG). The Hh ligands are often expressed in the epithelia, affecting the surrounding mesenchyme, and thus constituting a form of paracrine signaling. The development of the urogenital organ, therefore, provides an intriguing opportunity to study EMI and its relationship with other pathways, such as hormonal signaling. Cellular interactions of prostate cancer (PCa) with its neighboring tissue is also noteworthy. The local microenvironment, including the bone metastatic site, can release cellular signals which can affect the malignant tumors, and vice versa. Thus, it is necessary to compare possible similarities and divergences in Hh signaling functions and its interaction with other local growth factors, such as BMP (bone morphogenetic protein) between organogenesis and tumorigenesis. Additionally, this review will discuss two pertinent research aspects of Hh signaling: (1) the potential signaling crosstalk between Hh and androgen signaling; and (2) the effect of signaling between the epithelia and the mesenchyme on the status of the basement membrane with extracellular matrix structures located on the epithelial-mesenchymal interface.