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

干细胞(SC)的激活和自我更新的调节对于成功的组织发育和 动态平衡。在许多组织中，这是由微环境中的支持细胞发出的信号来协调的 被称为SC利基市场。彻底了解哺乳动物干细胞龛细胞是如何编程和 在发育过程中调节干细胞的功能是未来组织特异性再生的关键要求 治疗。虽然从无脊椎动物的研究中获得了许多知识，但分子上的理解 哺乳动物干细胞壁龛中的细胞，如骨髓、脑、肠和毛囊， 由于组织的复杂性和缺乏方法，获得它们的专门地位是未知的 分离并鉴定细胞。我们最近开发了新的遗传工具来研究毛乳头 (DP)毛囊SC龛中的细胞，被认为决定毛囊SC的命运。我们已经提纯了这些 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。这就确立了 这是一个亟需的哺乳动物模型，可以用来研究SC生态位的形成和功能。我们的长- 学期目标是了解支配SC生态位命运规范的分子机制，使用 以毛囊形态发生与再生为模型系统。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)。在这项提案中，我们将 检验DP签名TF包含调节SC所必需且充分的活动的假设 激活，毛发诱导DP利基命运。我们将系统地操作DP细胞中的签名Tf表达 在体外和体内，以确定转录控制机制，指定分子身份和 DP壁龛细胞的功能活性。我们将进一步建立一个新的可诱导的体内DP特异性基因 瞄准目前在现场失踪的鼠标型号。最后，我们将使用以下可用鼠标进行测试 以条件性基因消融为靶点，候选DP签名TF对DP生态位命运的必要性 规范，使用这一新的体内基因消融模型，并与我们建立的体外/体内基因消融模型并行 杂交基因敲除试验。我们的工作将确定头发SC生态位命运的核心转录调控 毛囊DP细胞。在分离的DP细胞和正常的成纤维细胞中激活转录程序 承诺扩大全功能细胞，用于皮肤重建的治疗。这些发现将 与其他再生组织具有全球相关性，在这些组织中，SC利基的作用是维持组织的动态平衡， 并有可能导致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.