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.

抽象的 四年前，Rajagopal Lab确定了Airway Hillock，这是一种新颖的鼠气上皮结构 未知功能。从那以后，丘陵在人类航空公司中报道了，这表明它们是进化的 保守。大多数气道被假性上皮覆盖，主要由基底细胞组成， 分泌俱乐部细胞和纤毛细胞。丘陵与三个主要方式与此上皮区分开：（1） 平面KRT13+（一个细胞角蛋白）细胞的分层表层的存在，该细胞位于基底茎的顶部。 细胞（2）缺乏纤毛细胞，以及（3）丘陵基底干细胞的复制增强。我们有 初步数据表明，小丘对多种形式的气道损伤有抵抗力 萘，烟草烟雾的关键组成部分和二氧化硫气体。我们有证据表明 小丘是储备干细胞的来源。小丘的分层性质类似于病理 发现的鳞状化生症也是特征性分层的，被认为是 鳞状肺癌。 维生素A缺乏代表气管中鳞状化生的可重复模型，子宫宫颈，子宫颈， 和小鼠和人类中的肾脏骨盆。在维生素A缺乏症的情况下，气管发展出扁平的非纤毛细胞 表达经典丘陵标记KRT13的群集。因此，我假设小丘是以前的 鳞状变质的未鉴定来源。我将使用不同细胞类型的遗传谱系跟踪，包括 在维生素A缺乏症的情况下，小丘确定维生素A缺乏症引起的原始细胞 鳞状化生。由于视黄酸（RA）是维生素A的活性代谢产物，因此我将定义RA的作用 关于丘陵扩展和差异化。为了调查小丘是否会响应RA缺乏症，我 将使用丘陵特定的谱系驱动器表达RA受体的主要负等位基因。我也会补充 RA和RA受体抑制剂进行再生测定法，以检查RA对Hillock介导的损伤的影响 维修。 最后，我假设小丘是重新上皮后造成气道伤害后的主要干细胞。的确， 先前的工作显示了各种能够扩展到受伤气道的细胞群体。 因此，目前尚不清楚是否需要丘陵进行有效的上皮维修以及它们是否是主要储备 上皮的干细胞。为了调查这一假设，我将在萘之前遗传灌溉丘陵 受伤是一种在香烟烟雾中发现的化学物质，以确定丘陵是否需要适当再生。