Phenotypic Specification in Skin Organogenesis

 描述(申请人提供)：我们的长期目标是研究皮肤外胚层器官的发育和再生，并将原理应用于再生医学。在过去的二十年里，我的实验室对这一目标做出了长期的承诺；我们已经取得了几项基本的科学发现，并在推进皮肤再生生物学方面取得了概念性的进展。在下一阶段，我们将整合最近完成的两项RO1资助的新发现，专注于破译皮肤器官发生中表型规范的机制，这是下一阶段皮肤再生医学的主要挑战。通过干细胞生物学和重新编程技术的进步，科学家现在能够以分离细胞或角质形成细胞单层的形式产生表皮祖细胞。如何引导这些祖细胞形成具有不同结构的皮肤，目前尚不清楚。了解这些过程对于确保创面移植物的正确再生至关重要。皮肤的一个基本特征是显著的区域差异，不同的皮肤类型(例如，面部皮肤和头皮无毛皮肤等)在不同的身体区域发育，以达到不同的目的。2，3我们假设，有能力的、分离的表皮前体细胞与真皮细胞相互作用形成重组皮肤，这一过程受环境信号的调控，随着发育时间的推移，环境信号会改变，从而产生特定的皮肤附属物表型。我们将重点关注三个基本方面，为每个过程使用最合适的动物模型。在AIM 1中使用小鼠和人类细胞，而在AIM 2和3中使用鸡皮，因为它具有显着的地区差异，非常适合实验分析。在目标1中，我们将采取多学科的方法来研究如何从分离的细胞产生重建的皮肤层。延时成像、转录组分析和分子扰动将被用来研究分离的细胞如何通过一系列多细胞形态转变自组装成分层结构。我们将重点研究MMPs在这一形态发生转变中的作用，并试图通过修改Wnt-MMPECM模块来重新激活成年鼠和人细胞的形态发生能力。在目标2中，我们将研究皮肤祖细胞在区域化过程中是如何被指定的。我们的初步数据表明，鳞片到羽毛的转换是通过一系列信号分子以一种循序渐进的方式进行的。在初步研究的基础上，我们将重点讨论SOX基因在建立这种层次结构中的作用。在目标3中，我们将研究器官成形的形态发生原理。我们将以羽毛为模型，重点研究附肢长度的调节。我们将评估这样一种假设，即复杂的器官形状是由定性定义原型表型的“核心电路”和以时间-空间方式定量修改特定尺寸参数的“调制电路”指定的。我们假设成纤维细胞生长因子和Zic信号分别可能是这种分子回路的例子。

 DESCRIPTION (provided by applicant): Our long term objectives are to study the development and regeneration of skin ectodermal organs and to apply the principles toward regenerative medicine. Over the last two decades, my laboratory has made a long term commitment to this goal; we have produced several basic scientific discoveries and made conceptual progress toward the advancement of skin regenerative biology. In the next phase, we will consolidate new findings from two recently completed RO1 grants to focus on deciphering the mechanism of phenotypic specification in skin organogenesis, a major challenge in the next phase of cutaneous regenerative medicine. Through progress in stem cell biology and reprogramming technology, scientists are now able to generate epidermal progenitors, in the form of dissociated cells or a keratinocyte monolayer. How to guide these progenitors to form skin with different architecture remains unknown. Understanding these processes is crucial to ensure proper regeneration of a wound graft. A fundamental feature of the skin is the striking regional variation, where distinct skin types (e.g., facial skin and scalp glabrous skin, etc) develop at different body regions to serve different purposes.2,3 We postulate that competent, dissociated, epidermal progenitors interact with dermal cells to form reconstituted skin, a process which is regulated by environmental signals which change over developmental time to generate specific skin appendage phenotypes. We will focus on three fundamental aspects, using the most appropriate animal models for each process. Mouse and human cells are used in Aim 1 whereas chicken skin is used for Aims 2 and 3 because it features remarkable regional differences ideal for experimental analyses. In Aim 1, we will take a multi-disciplinary approach to study how the reconstituted skin layer is generated from dissociated cells. Time-lapse imaging, transcriptome analyses and molecular perturbation will be used to study how the dissociated cells can self-assemble into a layered configuration via a series of multicellular morphological transitions. We will focus on the roles of MMPs in this morphogenetic transition and will attempt to reactivate the morphogenetic ability in adult mouse and human cells by modifying the Wnt-MMP-ECM module. In Aim 2, we will study how skin progenitors are specified during regionalization. Our preliminary data suggests that the conversion of scales to feathers proceeds in a stepwise manner via a hierarchy of signaling molecules. Based on preliminary studies, we will focus on the role of Sox genes in establishing this hierarchy. In Aim 3, we will study the morphogenetic principles of organ shaping. We will focus on the regulation of appendage length using feathers as a model. We will evaluate the hypothesis that complex organ shapes are specified by a "core circuit" that defines a prototypic phenotype qualitatively and "modulator circuits" that modify specific dimensional parameters quantitatively in a temporal-spatial manner. We hypothesize that FGF and Zic signaling, respectively, may be examples of such molecular circuits.