The Hair Follicle Infundibulum: A Potential Mediator of Skin Barrier Function

描述(申请人提供)：皮肤的一个主要功能是产生一种保护屏障，使我们免受环境的影响。这一过程是由角质形成干细胞介导的，其后代分层并分化，最终形成由死亡细胞和交联型蛋白质物质组成的不溶支架。这种屏障的形成是在胚胎发育过程中完成的，是生命所必需的。虽然皮肤在屏障功能中的作用已经得到了很好的证实，但毛囊是否也在这一过程中发挥作用还没有研究。特别是，毛囊漏斗是一个特征不佳的领域 看起来与皮肤上皮连续的细胞。位于毛囊的嘴上， 漏斗细胞是多层的，暴露在外部环境中。这些特征表明漏斗细胞需要和能力形成屏障。NIAMS的使命之一是支持深入研究皮肤病的原因、治疗和预防的研究。这一建议与这一使命是一致的，因为我们的长期目标是研究胚胎发育、成人动态平衡和疾病扰动过程中漏斗细胞的特征。事实上，包括寻常痤疮在内的各种皮肤病特别发生在漏斗处，在更严重的情况下，可能会导致这一区域的破裂(并可能破坏屏障功能)，从而导致炎症性疾病。这项建议试图阐明漏斗，着眼于阐明粉刺的机制原因。在特定的目标1中，我们将分离新生和成年小鼠肾漏斗细胞，并通过RNA测序鉴定它们的基因表达模式。我们还将详细分析这些细胞在形成漏斗的分化的基底层上时的运动情况。这一开放目标的结果将增进我们对这一领域的理解，并为后续目标的使用提供工具和标记。在特定的目标2中，我们将通过破坏引起小鼠漏斗的干细胞中的Notch通路组件来测试Notch信号在漏斗中的作用。重要的是，这将使我们能够评估毛囊本身是否在屏障功能中发挥作用，并可能导致改进的粉刺小鼠模型的产生。在特定的目标3中，我们将检查Notch信号和分化缺陷是否是人类痤疮形成的基础。这将通过分析痤疮治疗前后患者的Notch信号和漏斗的一组标志物来完成。这些翻译研究将补充我们在小鼠身上的基本实验，并有望为这种疾病的病因提供机械性的见解。

DESCRIPTION (provided by applicant): A major function of the skin is to generate a protective barrier that shields us from our environment. This process is mediated by keratinocyte stem cells whose progeny stratify and differentiate, eventually forming an insoluble scaffold of dead cells and cross-linked proteinaceous material. Formation of this barrier is completed during embryonic development and is essential for life. Although the skin's role in barrier function is well-established, whether the hair follicle also plays a role in this process hs not been studied. In particular, the hair follicle infundibulum is a poorly characterized domain of cells that appears continuous with the skin epithelium. Situated at the mouth of the hair follicle, infundibular cells are multi-layered and exposed to the outer environment. These characteristics suggest both the need and capacity for infundibular cells to form a barrier. One of the missions of NIAMS is to support research that delves into the causes, treatment, and prevention of skin diseases. This proposal is concordant with that mission since our long-term objective is to characterize infundibular cells during embryonic development, adult homeostasis and disease perturbation. Indeed, a variety of skin disorders, including acne vulgaris, arises specifically at the infundibulum, and in more severe cases may cause rupture of this domain (and, presumably, disrupt barrier function), leading to inflammatory disease. This proposal seeks to shed light on the infundibulum, with an eye towards elucidating the mechanistic causes of acne. In Specific Aim 1, we will isolate both nascent and adult mouse infundibular cells, and characterize their gene expression patterns by RNA-Sequencing. We will also analyze in detail the movement of these cells as they form the differentiated, suprabasal layers of the infundibulum. Results from this opening Aim will improve our understanding of this domain, and provide tools and markers for use in the subsequent Aims. In Specific Aim 2, we will test the role of Notch signaling in the infundibulum by disrupting Notch pathway components specifically in the stem cells that give rise to the infundibulum in mice. Importantly, this will enable us to assess whether the hair follicle itself plays a role in barrier function, and may lead to the generation of improved mouse models of acne. In Specific Aim 3, we will examine whether Notch signaling and differentiation defects underlie acne formation in humans. This will be accomplished by analyzing a panel of markers, both for Notch signaling and the infundibulum, in patients prior to and after acne therapy. These translational studies will complement our basic experiments in mice, and will hopefully provide mechanistic insights into the causes of this disease