Molecular mechanisms controlling skin heterogeneity

皮肤的不同区域在它们的特性方面不同，例如厚度、色素沉着、神经支配和 毛囊和汗腺的存在，大小和密度，反映在对 伤害和疾病。例如，雄激素性脱发仅限于头皮;痤疮在面部占主导地位。 皮肤;银屑病通常在伸肌区域最突出;掌跖角化病仅限于手掌， 脚底;和白癜风可以出现在对称的模式。在建立皮肤的区域特征的同时， 在胎儿发育期间，位置信息必须在整个生命过程中保留在皮肤中， 局部特征的维持及其在伤口愈合中的重建。位置信息 已知存在于皮肤真皮中，但其分子基础知之甚少。为了解决这个问题，我们 提出以下具体目标。目的1：确定参与的候选因子和染色质区域， 在胚胎发生中建立皮肤异质性，我们将通过单细胞分析转录谱， RNA-seq和染色质结构，通过单细胞ATAC-seq，在发育中的皮肤的不同区域，以确定 分别表现出区域特定表达或开放性的那些。目标2：（一）确定其中哪些 候选因子和染色质区域也可能是维持局部皮肤异质性的原因， 在成人生活中，我们将对成人皮肤的相应区域进行相同的分析。(ii)我们假设 表观遗传机制有助于维持局部皮肤特征。为了验证这一点，我们将首先 鉴定DNA甲基化和组蛋白修饰的模式，这些模式表征了特定的 通过进行亚硫酸氢盐测序来揭示DNA甲基化的位点，并对组蛋白进行CUT&RUN， 标记增强子和活性、抑制或准备基因的修饰。然后我们会问， 在相同区域的成体真皮细胞中保持着这种模式。目的3：测试候选人的功能 在指导和维持区域特异性分化程序的调节，我们将使用诱导遗传 工具删除相应的基因在发育或成年小鼠真皮在体内。所有这些 实验提供了一种全面和公正的方法，以确定新的机制，建立和 维持皮肤异质性。对这些机制的进一步理解有可能揭示新的 伤口愈合以及影响特定皮肤区域的常见和罕见疾病中的治疗靶点， 对生活质量产生重大负面影响;本项目中获得的数据还将为以下战略提供信息： 产生特定的皮肤类型，包括带有毛囊和汗腺的皮肤，用于修复性皮肤移植。

Different regions of the skin vary in their characteristics such as thickness, pigmentation, innervation, and presence, size and density of hair follicles and sweat glands, that are reflected in differential responses to injury and disease. As examples, androgenetic alopecia is limited to the scalp; acne predominates in facial skin; psoriasis is often most prominent in extensor regions; palmoplantar keratoderma is limited to palms and soles; and vitiligo can appear in symmetrical patterns. While regional characteristics of the skin are established during fetal development, positional information must be retained in the skin throughout life to allow for maintenance of regional characteristics and their re-establishment in wound healing. Positional information is known to reside in the skin dermis, but its molecular basis is poorly understood. To address this question, we propose the following Specific Aims. AIM 1: To identify candidate factors and areas of chromatin involved in establishing skin heterogeneity in embryogenesis we will analyze transcriptional profiles through single cell RNA-seq, and chromatin structure via single cell ATAC-seq, in distinct regions of developing skin to identify those that show region-specific expression or openness, respectively. AIM 2: (i) To determine which of these candidate factors and chromatin areas may also be responsible for maintaining regional skin heterogeneity in adult life, we will perform the same analyses on the corresponding areas of adult skin. (ii) We hypothesize that epigenetic mechanisms contribute to maintenance of regional skin characteristics. To test this, we will first identify patterns of DNA methylation and histone modifications that characterize developing dermis in specific skin regions by carrying out Bisulfite-seq to reveal sites of DNA methylation, and CUT&RUN for histone modifications that mark enhancers and active, repressed, or poised genes. We will then ask which of these patterns are maintained in adult dermal cells from the same regions. AIM 3: To test the functions of candidate regulators in directing and maintaining region-specific differentiation programs, we will use inducible genetic tools to delete the corresponding genes in developing or adult mouse dermis in vivo. Together, these experiments provide a comprehensive and unbiased approach to identify novel mechanisms that establish and maintain skin heterogeneity. Improved understanding of these mechanisms has potential to reveal new therapeutic targets in wound healing and in common and rare diseases that affect specific skin regions and have a major negative impact on quality of life; data obtained in this project will also inform strategies for generating specific skin types, including hair follicle- and sweat gland-bearing skin, for reparative skin grafting.