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Amato CM, Xu X, Yao HHC. An extra-genital cell population contributes to urethra closure during mouse penis development. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.09.564741. [PMID: 37986842 PMCID: PMC10659392 DOI: 10.1101/2023.11.09.564741] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2023]
Abstract
Hypospadias, or incomplete closure of the urethra along the penis, is the second most common birth defect in the United States. We discovered a population of extra-genital mesenchymal cells that are essential for proper penile urethra closure in mouse embryos. This extra-genital population first appeared in the mesenchyme posterior to the hindlimb of the fetus after the onset of penis formation. These extra-genital cells, which transiently express a lineage marker Nr5a1, migrated centrally and colonized the penis bilateral to the urethra epithelium. Removal of the Nr5a1+ extra-genital cells, using a cell-type specific ablation model, resulted in severe hypospadias. The absence of extra-genital cells had the most significant impacts on another mesenchymal cells, the peri-urethra that were immediately adjacent to the Nr5a1+ extra-genital cells. Single cell mRNA sequencing revealed that the extra-genital cells extensively interact with the peri-urethra, particularly through Neuregulin 1, an epidermal Growth Factor (EGF) ligand. Disruption of Neuregulin 1 signaling in the ex-vivo slice culture system led to failure of urethra closure, recapitulating the phenotypes of extra-genital cell ablation. These results demonstrate that the Nr5a1+ extra-genital mesenchymal cells from outside of the fetal penis are indispensable for urethra closure through their interaction with the peri-urethra mesenchymal cells. This discovery provides a new entry point to understand the biology of penis formation and potential causes of hypospadias in humans.
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Affiliation(s)
- Ciro Maurizio Amato
- Reproductive Developmental Biology Group, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA
| | - Xin Xu
- Epigenetics and Stem Cell Biology Laboratory, National Institute of Environmental Health Sciences, Research Triangle Park, NC, US
| | - Humphrey Hung-Chang Yao
- Reproductive Developmental Biology Group, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA
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2
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Tarulli GA, Cripps SM, Pask AJ, Renfree MB. Spatiotemporal map of key signaling factors during early penis development. Dev Dyn 2021; 251:609-624. [PMID: 34697862 PMCID: PMC9539974 DOI: 10.1002/dvdy.433] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Revised: 08/27/2021] [Accepted: 09/28/2021] [Indexed: 12/31/2022] Open
Abstract
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.
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Affiliation(s)
- Gerard A Tarulli
- School of BioSciences, The University of Melbourne, Melbourne, Victoria, Australia
| | - Samuel M Cripps
- School of BioSciences, The University of Melbourne, Melbourne, Victoria, Australia
| | - Andrew J Pask
- School of BioSciences, The University of Melbourne, Melbourne, Victoria, Australia
| | - Marilyn B Renfree
- School of BioSciences, The University of Melbourne, Melbourne, Victoria, Australia
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3
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Development of a putative adverse outcome pathway network for male rat reproductive tract abnormalities with specific considerations for the androgen sensitive window of development. Curr Res Toxicol 2021; 2:254-271. [PMID: 34401750 PMCID: PMC8350458 DOI: 10.1016/j.crtox.2021.07.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2021] [Revised: 07/13/2021] [Accepted: 07/14/2021] [Indexed: 02/06/2023] Open
Abstract
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.
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Key Words
- AGD, Anogenital distance
- AO, Adverse Outcome
- AOP, Adverse Outcome Pathway
- Adverse outcome pathway
- Adverse outcome pathway network
- DBP, Dibutyl phthalate
- DEHP, Di(2-ethylhexyl)phthalate
- DHT, 5α-dihydrotestosterone
- DPP, Dipentyl phthalate
- E, Embryonic day (ED1=GD1 gestational day 1)
- GD, Gestational day (GD1=ED1 embryonic day 1)
- KE, Key event
- KER, Key event relationship
- LMWP, low molecular weight phthalate straight chain length of the esterified alcohols between 3 and 6 carbon atoms
- MPW, male programming window
- Male programming window
- Phthalate
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4
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Wang S, Lawless J, Zheng Z. Prenatal low-dose methyltestosterone, but not dihydrotestosterone, treatment induces penile formation in female mice and guinea pigs†. Biol Reprod 2020; 102:1248-1260. [PMID: 32219310 PMCID: PMC7253790 DOI: 10.1093/biolre/ioaa035] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Revised: 12/04/2019] [Accepted: 03/24/2020] [Indexed: 02/06/2023] Open
Abstract
Genital tubercle has bisexual potential before sex differentiation. Females exposed to androgen during sex differentiation show masculinized external genitalia, but the effects of different androgens on tubular urethral and penile formation in females are mostly unknown. In this study, we compared the masculinization effects of commonly used androgens methyltestosterone, dihydrotestosterone, and testosterone on the induction of penile formation in females. Our results suggested that prenatal treatment with low doses of methyltestosterone, but not same doses of dihydrotestosterone or testosterone, could induce penile formation in female mice. The minimum dose of dihydrotestosterone and testosterone for inducing tubular urethral formation in female mice was, respectively, 50 and 20 times higher than that of methyltestosterone. In vivo methyltestosterone treatment induced more nuclear translocation of androgen receptors in genital tubercles of female mice, affected Wnt signaling gene expressions, and then led to similar patterns of cell proliferation and death in developing genital tubercles to those of control males. We further revealed that low-dose methyltestosterone, but not same dose of dihydrotestosterone or testosterone, treatment induced penile formation in female guinea pigs. Exposure of female mouse genital tubercle organ culture to methyltestosterone, dihydrotestosterone, or testosterone could induce nuclear translocation of androgen receptors, suggesting that the differential effect of the three androgens in vivo might be due to the hormonal profile in mother or fetus, rather than the local genital tissue. To understand the differential role of these androgens in masculinization process involved is fundamental to androgen replacement therapy for diseases related to external genital masculinization.
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Affiliation(s)
- Shanshan Wang
- Department of Physiology, School of Medicine, Southern Illinois University Carbondale, Carbondale, IL, USA
| | - John Lawless
- Department of Physiology, School of Medicine, Southern Illinois University Carbondale, Carbondale, IL, USA
| | - Zhengui Zheng
- Department of Physiology, School of Medicine, Southern Illinois University Carbondale, Carbondale, IL, USA
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5
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Abstract
On January 21, 2017, I received an E-mail from Herb Tabor that I had been simultaneously hoping for and dreading for several years: an invitation to write a "Reflections" article for the Journal of Biological Chemistry On the one hand, I was honored to receive an invitation from Herb, a man I have admired for over 40 years, known for 24 years, and worked with as a member of the Editorial Board and Associate Editor of the Journal of Biological Chemistry for 17 years. On the other hand, the invitation marked the waning of my career as an academic scientist. With these conflicting emotions, I wrote this article with the goals of recording my career history and recognizing the many mentors, trainees, and colleagues who have contributed to it and, perhaps with pretension, with the desire that students who are beginning a career in research will find inspiration in the path I have taken and appreciate the importance of luck.
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Affiliation(s)
- David W Russell
- From the Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9046
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6
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Savchuk I, Morvan ML, Antignac JP, Gemzell-Danielsson K, Le Bizec B, Söder O, Svechnikov K. The human genital tubercle is steroidogenic organ at early pregnancy. Mol Cell Endocrinol 2018; 477:148-155. [PMID: 29928928 DOI: 10.1016/j.mce.2018.06.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Revised: 05/31/2018] [Accepted: 06/16/2018] [Indexed: 11/19/2022]
Abstract
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.
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Affiliation(s)
- I Savchuk
- Department of Women's and Children's Health, Pediatric Endocrinology Unit, Karolinska Institutet & University Hospital, SE-17176, Stockholm, Sweden
| | - M L Morvan
- LUNAM Université, École nationale vétérinaire, agroalimentaire et de l'alimentation Nantes-Atlantique (Oniris), Laboratoire d'Étude des Résidus et Contaminants dans les aliments (LABERCA), UMR INRA, 1329, Nantes, France
| | - J P Antignac
- LUNAM Université, École nationale vétérinaire, agroalimentaire et de l'alimentation Nantes-Atlantique (Oniris), Laboratoire d'Étude des Résidus et Contaminants dans les aliments (LABERCA), UMR INRA, 1329, Nantes, France
| | - K Gemzell-Danielsson
- Department of Women's and Children's Health, Divivision of Obstetrics and Gynecology, Karolinska Institutet & University Hospital, Stockholm, Sweden
| | - B Le Bizec
- LUNAM Université, École nationale vétérinaire, agroalimentaire et de l'alimentation Nantes-Atlantique (Oniris), Laboratoire d'Étude des Résidus et Contaminants dans les aliments (LABERCA), UMR INRA, 1329, Nantes, France
| | - O Söder
- Department of Women's and Children's Health, Pediatric Endocrinology Unit, Karolinska Institutet & University Hospital, SE-17176, Stockholm, Sweden
| | - K Svechnikov
- Department of Women's and Children's Health, Pediatric Endocrinology Unit, Karolinska Institutet & University Hospital, SE-17176, Stockholm, Sweden.
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7
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Suzuki H, Suzuki K, Yamada G. Systematic analyses of murine masculinization processes based on genital sex differentiation parameters. Dev Growth Differ 2015; 57:639-47. [DOI: 10.1111/dgd.12247] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Revised: 10/08/2015] [Accepted: 10/09/2015] [Indexed: 11/28/2022]
Affiliation(s)
- Hiroko Suzuki
- Department of Developmental Genetics; Institute of Advanced Medicine; Wakayama Medical University; 811-1 Kimiidera Wakayama 641-8509 Japan
| | - Kentaro Suzuki
- Department of Developmental Genetics; Institute of Advanced Medicine; Wakayama Medical University; 811-1 Kimiidera Wakayama 641-8509 Japan
| | - Gen Yamada
- Department of Developmental Genetics; Institute of Advanced Medicine; Wakayama Medical University; 811-1 Kimiidera Wakayama 641-8509 Japan
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8
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Sexually dimorphic expression of Mafb regulates masculinization of the embryonic urethral formation. Proc Natl Acad Sci U S A 2014; 111:16407-12. [PMID: 25362053 DOI: 10.1073/pnas.1413273111] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
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.
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9
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Kim TS, Jung KK, Kim SS, Kang IH, Baek JH, Nam HS, Hong SK, Lee BM, Hong JT, Oh KW, Kim HS, Han SY, Kang TS. Effects of in utero exposure to DI(n-Butyl) phthalate on development of male reproductive tracts in Sprague-Dawley rats. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2010; 73:1544-1559. [PMID: 20954080 DOI: 10.1080/15287394.2010.511579] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The purpose of this study was to determine the effects of di(n-butyl) phthalate (DBP) administration on male reproductive organ development in F1 Sprague-Dawley rats following in utero exposure. During gestation days (GD) 10-19, pregnant rats were administered daily, orally, DBP at 250, 500, or 700 mg/kg or flutamide (1, 12.5, or 25 mg/kg/d) as a positive control. The male offspring were sacrificed at 31 d of age. DBP and flutamide dose-dependently significantly increased the incidence of hypospadias and cryptorchidism in F1 male offspring. The weights of testes and accessory sex organs (epididymides, seminal vesicles, ventral prostate, levator ani plus bulbocavernosus muscles (LABC), and Cowper's glands) were significantly reduced in DBP-treated animals. Furthermore, cauda agenesis of epididymides and ventral prostate atrophy were observed in high-dose 700-mg/kg DBP males. Anogenital distance (AGD) and levels of dihydrotestosterone (DHT) and testosterone were significantly decreased in the DBP (700 mg/kg/d)-treated groups. In particular, the expression of androgen receptor (AR) and 5α-reductase type 2 in the proximal penis was markedly depressed following administration of DBP (700 mg/kg/d) or flutamide (25 mg/kg/d). The expression of sonic hedgehog (Shh) in the urethral epithelium of the proximal penis was significantly less in the DBP (700 mg/kg/d)- or flutamide (25 mg/kg/d)-treated groups. In addition, DBP dose-dependently significantly increased the expression of estrogen receptor (ER α) in the undescended testis. Data demonstrated that in utero exposure to DBP produced several abnormal responses in male reproductive organs, and these effects may be due to disruption of the stage-specific expression of genes related to androgen-dependent organs development.
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Affiliation(s)
- Tae Sung Kim
- Health Effects Analysis Team, National Institute of Food and Drug Safety Evaluation, Korea Food and Drug Administration, Seoul, South Korea
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10
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OGINO YUKIKO, SUZUKI KENTARO, HARAGUCHI RYUMA, SATOH YOSHIHIKO, DOLLE PASCAL, YAMADA GEN. External Genitalia Formation. Ann N Y Acad Sci 2006. [DOI: 10.1111/j.1749-6632.2001.tb03983.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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11
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Petiot A, Perriton CL, Dickson C, Cohn MJ. Development of the mammalian urethra is controlled by Fgfr2-IIIb. Development 2005; 132:2441-50. [PMID: 15843416 DOI: 10.1242/dev.01778] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Development of external genitalia in mammalian embryos requires tight coordination of a complex series of morphogenetic events involving outgrowth,proximodistal and dorsoventral patterning, and epithelial tubulogenesis. Hypospadias is a congenital defect of the external genitalia that results from failure of urethral tube closure. Although this is the second most common birth defect in humans, affecting one in every 250 children, the molecular mechanisms that regulate morphogenesis of the mammalian urethra are poorly understood. We report that mice lacking the IIIb isoform of fibroblast growth factor receptor 2 (Fgfr2) exhibit severe hypospadias. Urethral signaling regions, as indicated by Shh and Fgf8 expression, are established in Fgfr2-IIIb null mice; however, cell proliferation arrests prematurely and maturation of the urethral epithelium is disrupted. Fgfr2-IIIb-/- mutants fail to maintain the progenitor cell population required for uroepithelial renewal during tubular morphogenesis. In addition, we show that antagonism of the androgen receptor (AR) leads to loss of Fgfr2-IIIb and Fgf10 expression in the urethra, and an associated hypospadias phenotype, suggesting that these genes are downstream targets of AR during external genital development. Genitourinary defects resulting from disruption of AR activity, by either genetic or environmental factors, may therefore involve negative regulation of the Fgfr2 pathway. This represents the first example of how the developing genitourinary system integrates cues from systemically circulating steroid hormones with a locally expressed growth factor pathway.
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Affiliation(s)
- Anita Petiot
- Cancer Research UK, Lincoln's Inn Fields, London WC2A 3PX, UK
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12
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Silver RI. Endocrine abnormalities in boys with hypospadias. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2004; 545:45-72. [PMID: 15086020 DOI: 10.1007/978-1-4419-8995-6_4] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/29/2023]
Abstract
The multifactorial etiology of hypospadias is becoming more clearly defined with ongoing investigation. Endogenous endocrine abnormalities identified so far include testosterone biosynthesis defects, 5alpha-reductase type 2 mutations, and androgen receptor mutations (the rarest cause, even in cases of severe hypospadias). Other significant risk factors include IVF (because of progesterone administration or endocrine abnormalities associated with infertility) and environmental agents that can potentially cause testicular dysgenesis, disrupt the male androgen axis, and disturb normal male genital embryology (Table 6). [table; see text] It also seems that the incidence of hypospadias is increasing, both in the United States and in Europe--which may be due to better medical care for those with genital abnormalities and/or infertility problems, as well as environmental endocrine disruptors. Hypospadias is a physical manifestation that may be a consequence of numerous physiological aberrations, and our ability to understand and to potentially prevent this congenital malformation will require a significant amount of additional work. Our challenge for the future remains to identify the various etiologies, provide prenatal counseling for affected families with a history of hypospadias, and minimize or eliminate exposure to environmental agents that may contribute to this problem. Perhaps one day we will be able to offer prenatal therapy to prevent hypospadias when the risk for this birth defect seems high. How might this be possible? Consider the modern management of a family with a child born with the adrenogenital syndrome, another endocrine derangement that can cause abnormal genital development. In this situation, dexamethasone can be administered to the mother in subsequent pregnancies to prevent fetal virilization until the sex of the fetus can be determined or adrenal enzyme mutations can be excluded. Perhaps in the future a similar approach will be taken for those families with strong risk factors for hypospadias.
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13
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Cunha GR, Baskin L. Development of the Penile Urethra. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2004; 545:87-102. [PMID: 15086022 DOI: 10.1007/978-1-4419-8995-6_6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/06/2023]
Affiliation(s)
- Gerald R Cunha
- Department of Anatomy, University of California, San Francisco, CA 94143-0452, USA.
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14
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Yamada G, Satoh Y, Baskin LS, Cunha GR. Cellular and molecular mechanisms of development of the external genitalia. Differentiation 2003; 71:445-60. [PMID: 14641326 DOI: 10.1046/j.1432-0436.2003.7108001.x] [Citation(s) in RCA: 133] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The limb and external genitalia are appendages of the body wall. Development of these structures differs fundamentally in that masculine development of the external genitalia is androgen dependent, whereas development of the limb is not. Despite this fundamental difference in developmental regulation, epithelial-mesenchymal interactions play key roles in the development of both structures, and similar regulatory molecules are utilized as mediators of morphogenetic cell-cell interactions during development of both the limb and external genitalia. Given the relatively high incidence of hypospadias, a malformation of penile development, it is appropriate and timely to review the morphological, endocrine, and molecular mechanisms of development of the genital tubercle (GT), the precursor of the penis in males and the clitoris in females. Morphological observations comparing development of the GT in humans and mouse emphasize the validity of the mouse as an animal model of GT development and validate the results of experimental studies. Accordingly, the use of mutant mice provides important insights into the roles of specific regulatory molecules in development of the external genitalia. While our current understanding of the morphological and molecular mechanisms of mammalian external genitalia development is still rudimentary, this review summarizes the current state of our knowledge and whenever possible draws from the rich experimental embryology literature on other relevant organs such as the developing limb. Future research on the hormonal and molecular mechanisms of GT development may yield strategies to prevent or reduce the incidence of hypospadias and to elucidate the molecular genetic mechanisms of GT morphogenesis, especially in relation to common organogenetic pathways utilized in other organ systems.
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Affiliation(s)
- Gen Yamada
- Center for Animal Resources and Development (CARD) and Graduate School of Medical and Pharmaceutical Sciences, Kumamoto University, Honjo, Kumamoto 860-0811, Japan
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15
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Suzuki K, Ogino Y, Murakami R, Satoh Y, Bachiller D, Yamada G. Embryonic development of mouse external genitalia: insights into a unique mode of organogenesis. Evol Dev 2002; 4:133-41. [PMID: 12004962 DOI: 10.1046/j.1525-142x.2002.01061.x] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The mammalian external genitalia are specialized appendages for efficient copulation, internal fertilization and display marked morphological variation among species. In this paper, we described the embryonic development of mouse genital tubercle (GT), an anlage of the external genitalia utilizing the scanning electron microscope (SEM) analysis. It has been shown that the Distal Urethral Epithelium (DUE) may fulfill an essential role in the outgrowth control of the GT. Our present SEM analysis revealed a small distal protrusion at the tip of the GT of normal embryos as well as some morphological differences between male and female embryonic external genitalia. Previous analysis shows that the teratogenic dose of Retinoic Acid (RA) induces a drastic marformation of the urethral plate, but not gross abnormalities for GT outgrowth. Interestingly, a small distal protrusion at the tip of GT was clearly observed also after RA treatement. Furthermore, we showed that treatment with anti-androgen flutamide resulted in the demasculinization of the GT in males. The unique character of GT development and the sexual dimorphism are discussed.
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Affiliation(s)
- Kentaro Suzuki
- Center for Animal Resources and Development and Graduate School of Molecular and Genomic Pharmacy, Kumamoto University, Japan
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16
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Mahendroo MS, Cala KM, Hess DL, Russell DW. Unexpected virilization in male mice lacking steroid 5 alpha-reductase enzymes. Endocrinology 2001; 142:4652-62. [PMID: 11606430 PMCID: PMC4446976 DOI: 10.1210/endo.142.11.8510] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Mice lacking steroid 5 alpha-reductase 1 and 2 were produced by gene targeting and breeding. Male mice without 5 alpha-reductase 2 or without both enzymes had fully formed internal and external genitalia and were fertile, but had smaller prostates and seminal vesicles than controls. T accumulated to high levels in the reproductive tissues of the mutant mice. DHT administration increased seminal vesicle and coagulating gland weights in mice deficient in 5 alpha-reductase 2 and increased the weights of the prostate, seminal vesicle, and coagulating gland in animals deficient in both enzymes. An inhibitor of both 5 alpha-reductases (GI 208335X) decreased prostate and coagulating gland weights of control mice, but had no effect in those lacking 5 alpha-reductase 1 and 2. Castration reduced the sizes of these tissues in animals of all genotypes. Androgen-dependent gene expression was decreased in the seminal vesicles of mice lacking one or more 5 alpha-reductases and was restored by administration of T or DHT. Female mice missing both enzymes exhibited parturition and fecundity defects similar to those of animals without 5 alpha-reductase 1. We conclude that T is the only androgen required for differentiation of the male urogenital tract in mice and that the synthesis of DHT serves largely as a signal amplification mechanism.
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Affiliation(s)
- M S Mahendroo
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
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Cao G, Zhao L, Stangl H, Hasegawa T, Richardson JA, Parker KL, Hobbs HH. Developmental and hormonal regulation of murine scavenger receptor, class B, type 1. Mol Endocrinol 1999; 13:1460-73. [PMID: 10478838 DOI: 10.1210/mend.13.9.0346] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The scavenger receptor, class B, type I (SR-BI), is the predominant receptor that supplies plasma cholesterol to steroidogenic tissues in rodents. We showed previously that steroidogenic factor-1 (SF-1) binds a sequence in the human SR-BI promoter whose integrity is required for high-level SR-BI expression in cultured adrenocortical tumor cells. We now provide in vivo evidence that SF-1 regulates SR-BI. During mouse embryogenesis, SR-BI mRNA was initially expressed in the genital ridge of both sexes and persisted in the developing testes but not ovary. This sexually dimorphic expression profile of SR-BI expression in the gonads mirrors that of SF-1. No SR-BI mRNA was detected in the gonadal ridge of day 11.5 SF-1 knockout embryos. Both SR-BI and SF-1 mRNA were expressed in the cortical cells of the nascent adrenal glands. These studies directly support SF-1 participating in the regulation of SR-BI in vivo. We examined the effect of cAMP on SR-BI mRNA and protein in mouse adrenocortical (Y1-BS1) and testicular carcinoma Leydig (MA-10) cells. The time courses of induction were strikingly similar to those described for other cAMP- and SF-1-regulated genes. Addition of lipoproteins reduced SR-BI expression in Y1-BS1 cells, an effect that was reversed by administration of cAMP analogs. SR-BI mRNA and protein were expressed at high levels in the adrenal glands of knockout mice lacking the steroidogenic acute regulatory protein; these mice have extensive lipid deposits in the adrenocortical cells and high circulating levels of ACTH. Taken together, these studies suggest that trophic hormones can override the suppressive effect of cholesterol on SR-BI expression, thus ensuring that steroidogenesis is maintained during stress.
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MESH Headings
- Adrenal Glands/embryology
- Adrenal Glands/metabolism
- Animals
- Animals, Newborn
- CD36 Antigens/genetics
- CD36 Antigens/metabolism
- Cholesterol/metabolism
- Cyclic AMP/analogs & derivatives
- Cyclic AMP/pharmacology
- DNA-Binding Proteins/genetics
- Embryo, Mammalian/metabolism
- Embryonic and Fetal Development/genetics
- Female
- Fushi Tarazu Transcription Factors
- Gene Expression Regulation, Developmental
- Genitalia/embryology
- Genitalia/metabolism
- Homeodomain Proteins
- Hormones/physiology
- Humans
- In Situ Hybridization
- Liver/embryology
- Liver/metabolism
- Male
- Membrane Proteins
- Mice
- Mice, Knockout
- Phosphoproteins/genetics
- Pregnancy
- RNA, Messenger/drug effects
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Receptors, Cytoplasmic and Nuclear
- Receptors, Immunologic
- Receptors, Lipoprotein/genetics
- Receptors, Lipoprotein/metabolism
- Receptors, Scavenger
- Scavenger Receptors, Class B
- Steroidogenic Factor 1
- Transcription Factors/genetics
- Transcription, Genetic
- Tumor Cells, Cultured
- Urogenital System/metabolism
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Affiliation(s)
- G Cao
- Department of Molecular Genetics, University of Texas Southwestern Medical Center at Dallas, 75235, USA
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Kurzrock EA, Baskin LS, Li Y, Cunha GR. Epithelial-mesenchymal interactions in development of the mouse fetal genital tubercle. Cells Tissues Organs 1999; 164:125-30. [PMID: 10352344 DOI: 10.1159/000016650] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Epithelial-mesenchymal interactions play a central role in the development of urogenital organs. We hypothesized that normal development of the external genitalia depends upon proper mesenchymal-epithelial signaling. The mesenchyme of the adult mouse penis consists of a corpus cavernosum and proximal and distal bones. The differentiation of penile mesenchyme into bone and cartilage begins after birth and can be accelerated by androgens. After determining the sex, genital tubercles of fetal mice at gestational day 15 were removed. The genital tubercles were trypsinized and microdissected to remove the epidermis and urethra from the mesenchyme. Recombinant specimens were created by combining genital tubercle mesenchyme with genital tubercle epithelium, bladder epithelium or tail epidermis. Tissues were grafted under the renal capsule of male athymic mice. After 3 weeks of growth, grafts were removed from the kidney, weighed and stained with hematoxylin and eosin, Alcian blue and peanut agglutinin. Male and female grafts showed no difference in growth or differentiation. Intact grafts and recombinant grafts, irrespective of the epithelial source, grew significantly more than grafts of the mesenchyme only. Recombinant grafts demonstrated a significantly higher prevalence of cartilage formation and mesenchymal differentiation compared to grafts of the mesenchyme without epithelium. Since heterologous epithelium is able to induce equivalent growth and differentiation of phallic mesenchyme, epithelium carries a permissive, but critical, role in genital mesenchyme development.
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Affiliation(s)
- E A Kurzrock
- Departments of Urology and Anatomy, University of California, San Francisco, Calif. 94143-0738, USA
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Sato T, Sonoda T, Itami S, Takayasu S. Predominance of type I 5alpha-reductase in apocrine sweat glands of patients with excessive or abnormal odour derived from apocrine sweat (osmidrosis). Br J Dermatol 1998; 139:806-10. [PMID: 9892945 DOI: 10.1046/j.1365-2133.1998.02504.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
High levels of 5alpha-reductase activity have been detected in human apocrine glands, and the concentration of dihydrotestosterone has been found to be higher than that of testosterone in the nuclear fraction of the skin of patients who suffer from excessive or abnormal odour derived from apocrine sweat (osmidrosis). Although these results suggest that 5alpha-reductase may play a central role in the action of androgens in the apocrine gland, the isozyme responsible is not known. We therefore assayed 5alpha-reductase type I and type II activity and mRNA expression in isolated apocrine glands from four patients with osmidrosis. When we incubated gland homogenates with [3H]testosterone, we found that the biochemical properties of the apocrine gland enzyme were consistent with those of type I 5alpha-reductase: at substrate concentrations of both 50 nmol/L and 1 micromol/L, the optimum pH was in the range 6.0-7.5, and the apparent Km was 21.1 micromol/L. The apocrine gland enzyme was inhibited by MK386, a specific inhibitor of type I 5alpha-reductase, in a dose-dependent manner, but it was hardly affected by finasteride, a specific inhibitor of type II isozyme, in that a nanomolar concentration of finasteride produced only a slight inhibition. Reverse transcriptase-polymerase chain reaction showed that the apocrine gland expressed type I 5alpha-reductase mRNA exclusively, except for a faint band of type II isozyme in a few preparations. These data indicate that the type I isozyme is the predominant form of 5alpha-reductase in the apocrine gland and may play a central role in the anabolic activity of androgens, as reported for the sebaceous gland. In addition, a small amount of type II isozyme may be expressed by mesenchymal cells that surround the apocrine glands and also contribute to their development.
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Affiliation(s)
- T Sato
- Department of Dermatology, Oita Medical University, 1-1, Idaiga-oka, Hazama-machi, Oita-gun, Oita 879-55, Japan
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