The Hillock: A Newly Discovered Airway Epithelial Structure and its Relationship with Squamous Metaplasia

小丘：新发现的气道上皮结构及其与鳞状上皮化生的关系

• 批准号: 10665873
• 负责人: Chaim Zev Chernoff
• 金额: $ 3.81万
• 依托单位: HARVARD MEDICAL SCHOOL
• 依托单位国家: 美国
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-09-30 至 2026-09-29
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10665873
• 关键词: Ablation; Adult; Alleles; Alveolus; Asthma; Atmosphere; Basal Cell; Biological Assay; Biology; Cells; Cellular Structures; Cervix Uteri; Chemicals; Chronic Obstructive Pulmonary Disease; Cystic Fibrosis; Cytokeratin; Data; Differentiation and Growth; Disease; Distal; Dominant-Negative Mutation; Environment; Epithelium; Gases; Genetic; Gland; Homeostasis; Human; Injury; Lesion; Lung; Maintenance; Malignant Squamous Cell Neoplasm; Mediating; Modeling; Molecular; Mus; Myoepithelial; Naphthalene; Natural regeneration; Nature; Oxygen; Pathologic; Pathway interactions; Population; Process; Proliferating; Pseudostratified Epithelium; Reagent; Renal pelvis; Reporting; Reproducibility; Reserve Stem Cell; Resistance; Retinoic Acid Receptor; Role; Signal Transduction; Smoking; Source; Squamous Cell Lung Carcinoma; Squamous Epithelium; Squamous Metaplasia; Structure; Sulfur Dioxide; Surface; Testing; Tissues; Tobacco smoke; Trachea; Tracheal Epithelium; Tretinoin; Vitamin A; Vitamin A Deficiency; Work; airway epithelium; airway regeneration; cell type; cigarette smoke; epithelial repair; epithelial stem cell; epithelium regeneration; inhibitor; injured airway; injury and repair; novel; premalignant; response; single-cell RNA sequencing; small molecule; stem cells

Abstract Four years ago, the Rajagopal lab identified the airway hillock, a novel murine airway epithelial structure of unknown function. Hillocks have since been reported in human airways, suggesting that they are evolutionarily conserved. Most of the airway is covered by pseudostratified epithelium, composed primarily of basal cells, secretory club cells, and ciliated cells. The hillock is distinguished from this epithelium in three major ways: (1) the presence of stratified-appearing layers of flat KRT13+ (a cytokeratin) cells which sit atop hillock basal stem cells (2) the lack of ciliated cells, and (3) the enhanced replication of the hillock basal stem cells. We have preliminary data demonstrating that the hillock is resistant to multiple forms of airway injury including naphthalene, a key component of tobacco smoke, and sulfur dioxide gas. We have evidence to suggest that hillocks serve as a source of reserve stem cells. The stratified nature of the hillock resembles the pathologic finding of squamous metaplasia that is also characteristically stratified, and which is thought to be a precursor of squamous lung cancer. Vitamin A deficiency represents a reproducible model of squamous metaplasia in the trachea, uterine cervix, and renal pelvis in mice and humans. In the setting of vitamin A deficiency, trachea develop flat non-ciliated cell clusters that express the classic hillock marker KRT13. I therefore hypothesize that hillocks are the previously unidentified source of squamous metaplasia. I will use genetic lineage tracing of different cell types including the hillock in the setting of vitamin A deficiency to determine the cell of origin of vitamin A deficiency-induced squamous metaplasia. Since retinoic acid (RA) is the active metabolite of vitamin A, I will define the role of RA on hillock expansion and differentiation. To investigate whether hillocks expand in response to RA deficiency, I will express a dominant negative allele of the RA receptor using a hillock specific lineage driver. I will also add RA and RA receptor inhibitor to regeneration assays to examine the effects of RA on hillock-mediated injury repair. Finally, I hypothesize that hillocks are the primary stem cell that re-epithelializes the airway post-injury. Indeed, previous work has shown a variety of cell populations capable of expanding to resurface the injured airway. Therefore, it is unclear if hillocks are required for efficient epithelial repair and if they are the primary reserve stem cell of the epithelium. To investigate this hypothesis, I will genetically ablate hillocks prior to naphthalene injury, a chemical found in cigarette smoke, to determine if hillocks are necessary for proper regeneration.

摘要 四年前，拉贾戈帕尔实验室发现了呼吸道丘，这是一种新的小鼠呼吸道上皮结构 未知函数。自那以后，人类呼吸道中出现了山丘，这表明它们在进化上是 保守的。大部分呼吸道被假性复层上皮覆盖，主要由基底细胞组成， 分泌杆状细胞和纤毛细胞。丘状上皮与这种上皮有三个主要的区别：(1) 位于丘状基干顶部的扁平KRT13+(一种细胞角蛋白)细胞层层的存在 细胞(2)缺乏纤毛细胞，(3)丘状基底干细胞复制增强。我们有 初步数据表明，丘状结构能抵抗多种形式的呼吸道损伤，包括 萘是烟草烟雾的关键成分，也是二氧化硫气体。我们有证据表明 山丘是储备干细胞的来源。山丘的分层性质类似于病理上的 鳞状化生的发现，也是典型的分层，被认为是 肺鳞癌。 维生素A缺乏代表了一种可复制的气管、宫颈、 以及小鼠和人类的肾盆。在维生素A缺乏的情况下，气管发育成扁平的无纤毛细胞 表达经典丘陵标记KRT13的簇。因此，我假设丘陵是以前的 来源不明的鳞状化生。我将使用不同细胞类型的遗传谱系追踪，包括 希洛克在维生素A缺乏症背景下确定维生素A缺乏症细胞来源的研究 鳞状化生。由于维甲酸(RA)是维生素A的活性代谢物，我将定义RA的作用 论丘陵的扩展与分化。为了研究山丘是否因RA缺乏而扩大，我 将使用山丘特有的谱系驱动程序表达RA受体的显性负等位基因。我还会补充一句 RA和RA受体阻断剂再生试验检测RA对丘脑损伤的影响 修理。 最后，我假设丘状细胞是损伤后呼吸道重新上皮化的主要干细胞。的确， 以前的工作已经表明，各种细胞群能够扩张，使受损的呼吸道重新浮出水面。 因此，尚不清楚丘状结构是否是有效的上皮修复所必需的，以及它们是否是主要的储备。 上皮干细胞。为了研究这一假设，我将先于萘对山丘进行基因切割。 损伤，一种在香烟烟雾中发现的化学物质，用来确定山丘是否对正常的再生是必要的。