Role of DAX1 in Testis Determination and Function

描述(申请人提供)：在过去的8年里，我们鉴定和描述了孤儿核受体DAX1和SF1自然发生突变的患者，并证明DAX1部分通过抑制SF1介导的转录发挥作用。利用定向突变，我们建立了小鼠Dax1基因敲除(KO)模型，并确定了Dax1在性腺决定、睾丸发育和成人睾丸功能中的作用。在这笔赠款中，我们建议延长这些研究，这些研究对性腺发育的机制提供了意想不到的见解。我们提出了三个相互关联的目标，分别关注Dax1的结构和作为转录抑制因子的功能，确定Dax1调控的遗传途径，并建立动物模型来揭示Dax1与其他参与睾丸发育和功能的基因的相互作用。具体地说，在目标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突变将被识别和表征，以阐明DAX1在体内发挥作用所需的关键结构域。在胚胎性腺文库的酵母双杂交筛选中确定的候选蛋白质将被进一步鉴定。目标2的目标是通过对12DPC时野生型和Dax1缺陷胚胎性腺表达的基因进行微阵列分析，确定Dax1调控的遗传途径。12DPC是Dax1在男性和女性中表达分化的时间点。目的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，我们将探索在不同细胞类型中选择性拯救Dax1的小鼠的性腺表型。此外，Dax1缺陷小鼠将与其他品系杂交，这些品系的遗传途径可能与Dax1交叉(例如，SF1、Sry、PTC)。这些目标的成功应该会在DAX1和转录抑制途径之间提供一个关键的联系，转录抑制途径将各种其他参与性腺发育的转录因子联系起来。

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.