Reproductive Developmental Biology Laboratory, National Institute of Environmental Health Sciences, Research Triangle Park, Durham, North Carolina, USA.
Department of Surgery, Division of Urology, University of Missouri, Columbia, Missouri, USA.
Reproduction. 2024 Sep 26;168(5). doi: 10.1530/REP-24-0239. Print 2024 Nov 1.
Female hypospadias is a little-known and poorly studied birth defect. This research establishes an anatomical and molecular foundation for future research to investigate the origins of this defect.
Hypospadias is a congenital anomaly of the external genitalia where the urethra does not properly close. In humans, hypospadias is mostly reported in male newborns, whereas in females hypospadias is rare, although it is generally considered to be under-reported. Improper urethra closure in the female genitalia can cause recurrent genitourinary tract infections and infertility. In mice, female hypospadias was induced by exposure to exogenous estrogenic compounds. Aside from the link between estrogen exposure and female hypospadias, the process of female urethra closure is largely unstudied, with the precise timing of urethra closure and associated molecular mechanisms remaining poorly understood. To address this gap, we determined when urethra closure occurs and identified gene expression patterns during the process of urethra closure in female neonatal mice from postnatal day (PND) 5 to 10. Using whole mount imaging and histology, we discovered that the initiation of urethra closure begins at PND7, and urethra closure is fully completed by PND10. To identify the genes associated with urethra closure, we conducted bulk RNA sequencing on female external genitalia prior to and after urethra closure. Gene ontology analyses revealed an increase in steroidogenic gene expression (Star, Hsd3b6, and Cyp17a1) during urethra closure, suggesting that the female genitalia locally produce steroids which could facilitate steroid signaling within the genitalia. With this study, we establish an anatomical timeline of female urethra closure and hypothesize a paracrine steroid signaling mechanism of urethra closure. These observations provide entry points to aid in further understanding external genital abnormalities, like hypospadias, in females.
女性尿道下裂是一种鲜为人知且研究不足的出生缺陷。本研究为未来研究探讨该缺陷的起源奠定了解剖学和分子基础。
尿道下裂是一种外生殖器先天畸形，尿道未能正常闭合。在人类中，尿道下裂主要发生在男性新生儿中，而女性尿道下裂则很少见，尽管它通常被认为是漏报的。女性外生殖器尿道闭合不当会导致反复泌尿道感染和不孕。在小鼠中，外源性雌激素化合物的暴露会诱发雌性尿道下裂。除了雌激素暴露与女性尿道下裂之间的联系外，女性尿道闭合的过程在很大程度上尚未得到研究，尿道闭合的确切时间和相关的分子机制仍知之甚少。为了解决这一差距，我们确定了尿道闭合发生的时间，并在雌性新生小鼠（出生后第 5 天至 10 天）的尿道闭合过程中确定了基因表达模式。通过全胚胎成像和组织学，我们发现尿道闭合的起始始于 PND7，PND10 时尿道完全闭合。为了鉴定与尿道闭合相关的基因，我们在尿道闭合前后对雌性外生殖器进行了 bulk RNA 测序。基因本体论分析显示，在尿道闭合过程中，类固醇生成基因（Star、Hsd3b6 和 Cyp17a1）的表达增加，这表明女性生殖器局部产生类固醇，这可能有助于生殖器内的类固醇信号转导。通过这项研究，我们建立了女性尿道闭合的解剖学时间表，并假设了尿道闭合的旁分泌类固醇信号机制。这些观察结果为进一步理解女性外生殖器异常（如尿道下裂）提供了切入点。
