Novel regulators of skin development and Foxn1 function

描述（由申请人提供）：本项目的目标是确定Foxn1的分子伴侣，并阐明其对皮肤发育的贡献。Foxn1是一种转录因子，含有一个翼状螺旋DNA结合结构域和一个带负电荷的反式激活结构域。在啮齿类动物中，Foxn1功能的丧失导致裸表型，其特征在于皮肤、胸腺和乳腺的异常形态发生。为了促进皮肤发育，Foxn1执行一种不寻常的功能，我们在以前的研究中描述了这一功能。Foxn1在上皮细胞启动表皮和毛囊的终末分化时被激活。Foxn1以位点依赖的方式发挥三种作用：1）它允许宿主细胞正确分化，2）它刺激宿主细胞的邻居分裂，3）它将黑素细胞招募到宿主细胞中，从而将其宿主识别为色素沉着的目标。通过这种作用的组合，Foxn1使细胞群能够协同工作，并共同驱动上皮细胞的生长、分化和色素沉着。据推测，Foxn1本身与其他因素协同工作，这些因素为它提供信息，决定其活动水平，将其引导到特定目标，或以协同方式与它并肩工作。毫无疑问，Foxn1需要这些伴侣才能发挥功效，这使得Foxn1的伴侣对皮肤和其他器官的形态发生至关重要。在这个项目的过程中，我们将使用两种方法来识别Foxn1的伴侣，一种是遗传学方法，另一种是生物化学方法。在遗传方法中，我们将筛选调节Foxn1活性或输出的突变。屏幕将采用一种新的模型系统，我们已经开发的研究。在生物化学方法中，我们将从角质形成细胞中纯化Foxn1蛋白复合物并解剖单个组分。一旦确定了合作伙伴，我们将确定它们如何促进Foxn1的作用和皮肤的形态发生。在人类中，FOXN1在序列和功能上是保守的，这表明伴侣的相似保守性。因此，通过阐明Foxn1的伙伴关系，该项目应该能够深入了解正常和患病人类皮肤的发育，特别是以上皮细胞异常增殖、分化或色素沉着为标志的疾病。项目叙述：该项目将阐明皮肤发育和再生其保护性上皮特征的基本机制。具体来说，这项工作将描绘一个遗传网络，驱动和协调皮肤外部结构的生长，分化和色素沉着。在短期内，该项目将部分解释皮肤如何产生和组装其对环境的屏障，这提供了对病原体，危险化学品，紫外线和水分流失的基本保护。从长远来看，该项目将深入了解皮肤如何在临床上产生或操纵，从而促进受损和患病皮肤的替换或修复方法。

DESCRIPTION (provided by applicant): The goal of this project is to identify the molecular partners of Foxn1 and to elucidate their contributions to skin development. Foxn1 is a transcription factor containing a winged-helix DNA-binding domain and a negatively charged transactivation domain. In rodents, the loss of Foxn1 function results in the nude phenotype, which is characterized by the abnormal morphogenesis of the skin, thymus, and mammary gland. To promote skin development, Foxn1 performs an unusual function, which was delineated by us in previous studies. Foxn1 becomes activated as epithelial cells initiate terminal differentiation in the epidermis and hair follicles. In a site-dependent manner, Foxn1 then plays up to three roles: 1) it allows its host cell to differentiate properly, 2) it stimulates the host cell's neighbors to divide, and 3) it recruits melanocytes to the host cell, thus identifying its host as a target for pigmentation. Through this combination of actions, Foxn1 enables groups of cells to work in concert and drives epithelial growth, differentiation, and pigmentation forward together. Presumably, Foxn1 itself works in concert with other factors, which provide it with information, determine its level of activity, direct it to specific targets, or function side-by-side with it in synergistic fashion. Undoubtedly, Foxn1 requires these partners for efficacy, making the partners of Foxn1 essential to the morphogenesis of the skin and other organs. During the course of this project, we will identify the partners of Foxn1 using two approaches, one genetic, the other biochemical. In the genetic approach, we will screen for mutations that modulate the activity or output of Foxn1. The screen will employ a novel model system, which we have developed for the study. In the biochemical approach, we will purify Foxn1 protein complexes from keratinocytes and dissect the individual components. Once partners are identified, we will determine how they contribute to the actions of Foxn1 and the morphogenesis of the skin. In humans, FOXN1 is conserved in sequence and function, suggesting a like conservation of partners. Accordingly, by elucidating the partnerships of Foxn1, the project should provide insight into the development of normal and diseased human skin, most especially, the disorders marked by the aberrant proliferation, differentiation, or pigmentation of epithelial cells. Project Narrative: This project will elucidate fundamental mechanisms by which the skin develops and regenerates its protective epithelial traits. Specifically, the work will delineate a genetic network that drives and coordinates the growth, differentiation, and pigmentation of the skin's external structures. In the short term, the project will explain in part how the skin produces and assembles its barrier to the environment, which provides essential protection against pathogens, hazardous chemicals, ultraviolet light, and water loss. Over the long term, the project will provide insight into how skin may be clinically generated or manipulated, thus facilitating methods for the replacement or repair of damaged and diseased skin.