DAX1 in Testis Determination and Function

描述（由申请人提供）：在过去的8年里，我们发现并鉴定了孤儿核受体DAX1和SF1自然发生突变的患者，并证明DAX1部分通过抑制SF1介导的转录起作用。利用靶向诱变技术，我们建立了小鼠Dax1基因敲除（KO）模型，并确定了Dax1基因在性腺决定、睾丸发育和成年睾丸功能中的作用。在这项资助中，我们建议扩展这些研究，这些研究为性腺发育机制提供了意想不到的见解。我们提出了3个相互关联的目标，重点关注Dax1作为转录抑制因子的结构和功能，确定由Dax1调节的遗传途径，并建立动物模型来揭示Dax1与睾丸发育和功能相关的其他基因的相互作用。具体来说，在Aim 1中，我们将确定介导DAX1转录抑制的分子伙伴。自然发生的DAX1突变将被鉴定和表征，以阐明体内DAX1功能所需的关键结构域。在胚胎性腺文库的酵母双杂交筛选中鉴定的候选蛋白将进一步表征。Aim 2的目标是通过微阵列分析野生型和Dax1缺陷胚胎性腺在12 dpc（雄性和雌性Dax1表达分化的时间点）中表达的基因，确定Dax1调控的遗传途径。Aim 3旨在探索Dax1与体内其他遗传途径的相互作用。利用缺乏Dax1的小鼠，我们将探索选择性拯救Dax1小鼠在各种细胞类型中的性腺表型。此外，Dax1缺陷小鼠将与其他与Dax1交叉的遗传通路发生改变的品系杂交（例如，Sf1, Sry, Ptc）。这些目标的成功应该提供DAX1和转录抑制途径之间的关键联系，而转录抑制途径与性腺发育中涉及的各种其他转录因子有关。

DESCRIPTION (provided by applicant): Over the last 8 years, we identified and characterized patients with naturally occurring mutations in the orphan nuclear receptors, DAX1 and SF1, and demonstrated that DAX1 acts in part by inhibiting SF1- mediated transcription. Using targeted mutagenesis, we developed a murine Dax1 knockout (KO) model and identified roles for Dax1 in gonadal determination, testis development, and adult testis function. In this grant, we propose to extend these studies, which have provided unexpected insight into mechanisms of gonadal development. We propose 3 inter-related aims that focus on Dax1 structure and function as a transcriptional repressor, identify genetic pathways regulated by Dax1, and develop animal models to unravel the interplay of Dax1 with other genes involved in testis development and function. Specifically, in Aim 1 we will identify molecular partners that mediate DAX1 transcriptional repression. Naturally occurring DAX1 mutations will be identified and characterized to elucidate key structural domains required for DAX1 function in vivo. Candidate proteins identified in a yeast two-hybrid screen of an embryonic gonadal library will be further characterized. The goal of Aim 2 is to identify the genetic pathways regulated by Dax1 using microarray analyses of genes expressed in wild type versus Dax1-deficient embryonic gonads at 12 dpc, a timepoint when Dax1 expression diverges in males and females. Aim 3 is designed to explore the interaction of Dax1 with other genetic pathways in vivo. Using mice that lack Dax1, we will explore the gonadal phenotypes of mice with selective rescue of Dax1 in various cell types. In addition, Dax1-deficient mice will be crossed to other strains with alterations in genetic pathways proposed to intersect with Dax1 (e.g., Sf1, Sry, Ptc). Success in these aims should provide a critical link between DAX1 and transcriptional repression pathways that link a variety of other transcription factors involved in gonadal development.