Resolving the Hierarchy and Regulation of Sebaceous Gland Stem Cells

项目摘要 皮脂腺（SG）是哺乳动物皮肤的附属物，其产生并分泌已知的脂质混合物。 作为皮脂。皮脂生产是至关重要的皮肤保养和偏差在正常的皮脂脂质生产 与包括寻常痤疮和脱发在内的几种皮肤病有关。皮脂生产进行 由皮脂腺细胞，组成的细胞群体的SG。皮脂腺细胞经历独特的成熟过程， 随着细胞膜的破裂而达到高潮。这一过程称为全分泌， 这导致了从SG分泌皮脂，但因此导致皮脂细胞死亡。由于脂质周转是一个函数， 在皮脂细胞周转中，皮脂细胞补充对于SG的功能维持至关重要。终身营业额 皮脂腺细胞的生长需要持续的细胞供应来补充和维持腺体，这表明 干细胞参与SG组织的维持。然而，内在和外在机制 调节假定的SG干细胞活性的机制尚未明确。这部分是由于限制 静态的组织学分析。这种实验方法只能及时捕获单个快照， 不足以描绘一个组织中的快速周转率的层次结构。而且 毛囊和SG之间的干细胞相关基因（如Sox 9）的重叠表达限制了 我们解释这些标记物在SG生理学中的功能作用的能力与头发分离。克服 这些限制，我结合了遗传谱系追踪工具与基于两个实时成像方法- 光子显微镜本研究的总体目标是通过结合一个活的 具有最先进的基因组学工具的成像系统，以1）表征SG稳态中的干细胞动力学 和再生，以及2）分析关键分子信号如何影响皮脂细胞命运， Sox 9。在我的初步实验中，我发现毛囊峡部的细胞，一个相邻的隔间， 皮肤特异性敲除Sox 9导致SG萎缩。我假设 皮脂腺细胞由来自峡部的异质干细胞群补充， 这是其调节和SG生理学所需的。本提案的目的1旨在解决皮脂腺 谱系层次，并测试在SG再生峡的必要性。本提案的目标2将涉及 SOX 9在调节皮脂腺细胞命运中的功能作用。本研究为SG的研究提供了一种新的方法 通过结合尖端成像技术和遗传学， 工具.该提案的目标是通过解决以下问题来揭示SG维护的基本机制： 皮脂细胞谱系和调节皮肤中SG干细胞活性的分子途径。

PROJECT SUMMARY Sebaceous glands (SGs) are appendages of mammalian skin that produce and secrete a mixture of lipids, known as sebum. Sebum production is crucial for skin maintenance and deviations in normal sebaceous lipid production are implicated in several skin pathologies including acne vulgaris and alopecia. Sebum production is carried out by sebocytes, the constituent cell population of SGs. Sebocytes undergo a unique maturation process which culminates with the rupture of the cell membrane. This process, termed holocrine secretion, facilitates the secretion of sebum from SGs, but consequently results in sebocyte death. As lipid turnover is a function of sebocyte turnover, sebocyte replenishment is critical to the functional maintenance of SGs. The lifelong turnover of sebocytes requires a continuous supply of cells to replenish and maintain the gland, which suggests the involvement of stem cells in the maintenance of SG tissues. However, the intrinsic and extrinsic mechanisms that regulate activity of the presumptive SG stem cells are not well defined. This is in part due to the limitations of static histological analyses. Such experimental approaches can only capture single snapshots in time, which are insufficient for delineating a hierarchical organization in a tissue with a rapid turnover rate. Furthermore, the overlapping expression of stem cell-associated genes, like Sox9, between the hair follicle and SGs has limited our ability to interpret the functional role of these markers in SG physiology uncoupled from the hair. To overcome these limitations, I have combined genetic lineage-tracing tools with live imaging approaches based on two- photon microscopy. The overall goal of this study is to implement an integrative approach by combining a live imaging system with state-of-the-art genomics tools to 1) characterize stem cell dynamics in SG homeostasis and regeneration by live imaging, and 2) analyze how sebocyte fate is influenced by the key molecular signal, Sox9. In my preliminary experiments, I found that cells from the hair follicle isthmus, an adjacent compartment, made cell contributions to SGs, and that skin-specific knockouts of Sox9 resulted in SG atrophy. I hypothesize that sebocytes are replenished by a heterogeneous stem cell population from the isthmus and that SOX9 is required for their regulation and SG physiology. Aim 1 of this proposal is designed to resolve the sebocyte lineage hierarchy and test the necessity of the isthmus in SG regeneration. Aim 2 of this proposal will address the functional role of SOX9 in regulating sebocyte fate. This research offers an innovative approach to study SG stem cells within the natural tissue environment by combining cutting-edge imaging technologies and genetic tools. The goal of this proposal is to uncover the fundamental mechanisms of SG maintenance by resolving the sebocyte lineage and molecular pathways that regulate SG stem cell activity in the skin.