The role of FoxA1 and FoxA2 in development of the anogenital system

描述（由申请人提供）：肛门生殖系统的发育需要精确调节生长和模式，这些过程中的缺陷会导致几种先天性出生缺陷。这些疾病包括尿道下裂（尿道管闭合失败导致尿道口异位）和持续性泄殖腔（消化道和泌尿生殖系统只有一个出口）。尽管肛门直肠畸形的发生率与发育过程中的问题有关，但对肛门生殖系统发育的胚胎学和分子调控知之甚少。该项目的目标是确定FoxA1和FoxA2，两个参与内胚层发育和分化的转录因子，在肛门生殖系统发育中的作用。我们的具体目标是（1）测试早期FoxA1和FoxA2是肛门生殖系统发育所必需的假设。我们将确定FoxA1; FoxA2条件性复合突变小鼠中持续泄殖腔的形态学和发育原因。此外，我们打算确定泄殖腔中的细胞命运是否在不存在FoxA1和FoxA2的情况下得以维持。（2）检验晚期FoxA1和FoxA2是外生殖器图案化所需的假设。我们将删除FoxA2在发育中的生殖器在稍后的图案化阶段，以确定时间的作用FoxA1和FoxA2的尿道的形态发生。为了检验FoxA1和FoxA2在外生殖器内启动分子模式化的假设，我们将检查FoxA1; FoxA2条件突变体在生殖器结节中表达的模式化基因的表达变化。最后，我们将确定FoxA1和FoxA2以及Sonic Hedgehog（Shh）之间的遗传关系。Shh在外生殖器的发育中至关重要，并且已经在Shh与其他内胚层来源的组织中的FoxA1和FoxA2之间建立了遗传关系。我们将通过检查Shh在FoxA1、FoxA2条件突变体中的表达来检验FoxA1和FoxA2调节Shh在结节中的表达和功能的假设。这项研究建议中提出的实验对理解人类肛门生殖器出生缺陷的基础具有重要意义。

DESCRIPTION (provided by applicant): The development of the anogenital system requires precise regulation of growth and patterning, and defect in these processes result in several congenital birth defects. These range from hypospadias, a failure in urethral tube closure resulting in ectopic urethral openings, to persistent cloaca, in which a single outlet exists for the alimentary and urogenital systems. Despite the incidence of anorectal malformations associated with problems during development, very little is known about the embryology and molecular regulation of the development of the anogenital system. The goal of this project is to define the role of FoxAl and FoxA2, two transcription factors involved in endoderm development and differentiation, in the development of the anogenital system. Our specific aims are to (1) Test the hypothesis that early FoxA1 and FoxA2 are required for development of the anogenital system. We will determine the morphological and developmental causes for persistent cloaca in FoxAl; FoxA2 conditional compound mutant mice. In addition, we intend to determine whether cell fate in cloaca is maintained in the absence of FoxAl and FoxA2. (2)Test the hypothesis that late FoxAl and FoxA2 are required for patterning the external genitalia. We will delete FoxA2 in the developing genitalia during later patterning stages to determine temporal role of FoxAl and FoxA2 in morphogenesis of the urethra. To test the hypothesis that FoxAl and FoxA2 initiate molecular patterning within the external genitalia, we will examine FoxAl; FoxA2 conditional mutants for changes in expression of patterning genes expressed in the genital tubercle. Finally, we will determine the genetic relationship between FoxAl and FoxA2, and Sonic Hedgehog (Shh). Shh is critical in development of the external genitalia, and a genetic relationship has been established between Shh and FoxAl and FoxA2 in other endodermally-derived tissues. We will test the hypothesis that FoxAl and FoxA2 regulate expression and function of Shh in the tubercle by examining the expression of Shh in FoxAl; FoxA2 conditional mutants. The experiments proposed in this research proposal have important implications for understanding the basis of human anogenital birth defects.