Specification of Dermal Papilla Cell Fate in the Hair Follicle Stem Cell Niche

干细胞（SC）激活和自我更新的调节对于组织的成功发育和发育是必要的。 体内平衡。在许多组织中，这是由微环境中支持细胞的信号精心策划的 称为 SC 利基。全面了解哺乳动物 SC 生态位细胞如何被编程和 发育过程中调节 SC 的功能是未来组织特异性再生的关键要求 疗法。虽然从无脊椎动物研究中获得了很多知识，但分子理解 哺乳动物 SC 生态位（例如骨髓、大脑、肠道和毛囊）中的生态位细胞如何 由于组织的复杂性和缺乏方法来获得它们的特殊状态是未知的 分离并表征细胞。我们最近开发了新的遗传工具来研究真皮乳头 毛囊 SC 生态位中的 (DP) 细胞被认为直接指导毛囊 SC 的命运。我们已经净化了这些 细胞，定义了它们的分子身份并建立了分析方法来研究它们的命运规范。这就建立了 一个急需的哺乳动物模型，可以研究 SC 生态位的形成和功能。我们的长期 术语目标是了解控制 SC 生态位命运规范的分子机制，使用 毛囊形态发生和再生作为模型系统。我们的工作已经确定了分子 DP 细胞的特征，包括一组信号和转录因子 (TF)。在本提案中，我们将 检验 DP 特征 TF 包含调节 SC 所需且充分的活动的假设 激活、头发诱导 DP 生态位命运。我们将系统地操纵 DP 细胞中的特征 TF 表达 体外和体内定义转录控制机制，指定分子身份和 DP 微环境细胞的功能活性。我们将进一步建立新型可诱导的DP特异性体内基因 目前该领域缺少针对小鼠模型。最后，我们将使用可用的小鼠进行测试 针对条件基因消融，候选 DP 特征 TF 对于 DP 生态位命运的必要性 规范，使用这种新颖的体内基因消融模型，并与我们建立的体外/体内平行 杂交敲除试验。我们的工作将确定头发 SC 生态位命运的核心转录调控 滤泡 DP 细胞。激活分离的 DP 细胞和常规成纤维细胞中的转录程序具有 有望扩展功能齐全的细胞，用于皮肤重建工作中的治疗用途。这些发现将 与其他再生组织具有全球相关性，其中 SC 生态位可维持组织稳态， 并有可能促进 3D 组织再生疗法的发展。

Regulation of stem cell (SC) activation and self-renewal is necessary for successful tissue development and homeostasis. In many tissues this is orchestrated by signals from supporting cells within the microenvironment called the SC niche. A thorough understanding of how mammalian SC niche cells become programmed and function during development to regulate SCs is a crucial requirement for future tissue-specific regenerative therapies. While much knowledge has been gained from studies in invertebrates, a molecular understanding of how niche cells in mammalian SC niches, such as the bone marrow, brain, intestine and hair follicles, acquire their specialized status is unknown due to the complexity of the tissues and the lack of methods to isolate and characterize the cells. We have recently developed novel genetic tools to study dermal papilla (DP) cells in the hair follicle SC niche, which are thought to direct follicular SC fate. We have purified these cells, defined their molecular identity and established assays to study their fate specification. This establishes a much needed mammalian model where formation and function of the SC niche can be studied. Our long- term goal is to understand the molecular mechanisms that govern SC niche fate specification, using hair follicle morphogenesis and regeneration as a model system. Our work has identified the molecular signature of DP cells, including a battery of signaling and transcription factors (TFs). In this proposal, we will test the hypothesis that the DP signature TFs contain the activity necessary and sufficient to regulate the SC activating, hair inducing DP niche fate. We will systematically manipulate signature TF expression in DP cells in vitro and in vivo to define the transcriptional control mechanisms that specify the molecular identity and functional activity of DP niche cells. We will further establish a novel inducible DP-specific in vivo gene targeting mouse model that is currently missing in the field. Finally, we will test with available mice that are targeted for conditional gene ablation, the necessity of candidate DP signature TFs for DP niche fate specification, using this novel in vivo gene ablation model, and in parallel with our established in vitro/in vivo hybrid knockout assay. Our work will identify the core transcriptional regulation of the SC niche fate of hair follicle DP cells. Activating the transcriptional program in isolated DP cells and in regular fibroblasts bears the promise to expand fully functional cells for therapeutic use in skin reconstructive efforts. These findings will have global relevance for other regenerative tissues, where SC niches operate to maintain tissue homeostasis, and potentially will lead to development of 3D-tissue regenerative therapies.