An in vitro screening system for genitalia development

About This Grant

Project Summary/Abstract Genital malformation including hypospadias represents the second most common male birth defect after cardiac defect. In the past 50 years, hypospadias incidence has doubled along with other male reproductive abnormalities. It is suspected that fetal exposure to endocrine disruptors may have contributed to this increase. However, the etiology of hypospadias is still largely unclear. Both environmental and genetic factors are involved. Thus, there is an urgent need to understand genetic pathways regulating urethral closure as well as lower urinary tract development in general. Unfortunately, insufficient prospective screening tools have prevented the rapid identification of causative genes. We have recently developed a streamlined forward genetic screening technology combining in vivo and in vitro approaches to rapidly identify crucial regulators of genital masculinization and lower urinary tract development. As a result, we have identified 31 high priority candidate transcription factors downstream of androgen receptor, regulating genital masculinization. In light of recent discovery that an extra-genital cell population migrates into the developing genitalia and is required for urethral closure, this proposal will use two purified GT mesenchymal populations to increase the cellular and functional resolution of our established high-throughput screening system. We will use these novel screening systems to reevaluate the function of transcription factors during urethral closure. In Aim I, we will use two tissue-specific mouse Cre lines to isolate pure populations of mesenchymal cells in the developing GT and test their cellular response to androgen stimulation. In Aim II, we will perform a proof-of-concept screen for transcription factors governing either their proliferation or migration. Together, these studies should greatly accelerate the discovery progress for master regulators of urethral closure. Our long-term goal is to use mouse molecular genetics to understand the process of urethral closure and the etiology of genital malformations, such as hypospadias.