Role of claudin 18 in regulation of lung stem/progenitor cell homeostasis

Claudin 18 在调节肺干/祖细胞稳态中的作用

• 批准号: 9212851
• 负责人: Zea Borok
• 金额: $ 17.43万
• 依托单位: UNIVERSITY OF SOUTHERN CALIFORNIA
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-02-01 至 2017-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9212851
• 关键词: AGTR2 gene; AMOT gene; Actins; Address; Adherens Junction; Adhesions; Adult; Alveolar; Apical; Apoptosis; Cell Count; Cell Differentiation process; Cell Nucleus; Cell Proliferation; Cell membrane; Cell physiology; Cell-Matrix Junction; Cells; Complex; Contact Inhibition; Cytoskeleton; Data; Desmosomes; Development; Epithelial; Equilibrium; Exhibits; Extracellular Domain; F-Actin; Family member; G-Protein-Coupled Receptors; Goals; Growth; Growth Factor; Homeostasis; In Vitro; Inhibition of Cell Proliferation; Injury; Intercellular Junctions; Ions; Knock-out; Knockout Mice; LATS1 gene; Lung; Mass Spectrum Analysis; Mechanics; Mediating; Molecular; Natural regeneration; Nuclear; Nuclear Translocation; Organ; Organ Size; Pathway interactions; Permeability; Phenotype; Phosphorylation; Phosphotransferases; Population; Process; Proteins; Regulation; Role; Series; Signal Pathway; Signal Transduction; Site; Stem cells; Stimulus; Stomach; Tight Junctions; Tissues; Transcription Coactivator; Transcriptional Coactivator with PDZ-Binding Motif; Wild Type Mouse; alpha catenin; alveolar epithelium; cell growth; extracellular; in vivo; lung development; lung injury; lung regeneration; lung repair; novel; organ regeneration; prevent; protein E; protein protein interaction; public health relevance; repaired; rho; solute; stem; tissue regeneration; transcription factor; tumor; tumorigenesis; upstream kinase

 DESCRIPTION (provided by applicant): Stem/progenitor cell proliferation and differentiation must be tightly regulated to maintain appropriate cell numbers for normal organ function while preventing tumorigenesis. Elucidation of mechanisms that regulate somatic stem/progenitor cell homeostasis is key to understanding how these populations are maintained and activated to meet demands for tissue regeneration following injury. Intercellular junctions, comprised of tight junctions (TJ), adherens junctions (AJ) and desmosomes, are sites of intercellular adhesion. Claudins are integral TJ proteins that regulate paracellular permeability. Claudin 18 (C18) is one of the most highly expressed Claudin family members in lung alveolar epithelium. We recently generated C18 knockout (KO) mice that exhibit increased lung epithelial permeability to ions and solutes. Intriguingly, C18 KO mice show expansion and increased proliferation of putative lung stem/progenitor cells (including alveolar epithelial type II (AT2) cells) and increased lung (and stomach) size, implicating integral TJ proteins (and C18 in particular) as novel regulators of epithelial stem/progenitor cell homeostasis and organ size. The Hippo signaling pathway regulates stem/progenitor cell function, organ size and regeneration through opposing effects on proliferation and apoptosis. Hippo signaling mediates contact inhibition of cell proliferation in vitro and limits tissue overgrowth in vivo via phosphorylation of upstream kinases that inhibit activity of orthologous downstream transcriptional co-activators, yes-associated protein (YAP) and transcriptional coactivator with PDZ binding motif (TAZ). Upstream regulators of Hippo signaling are not well characterized but include extracellular stimuli via G-protein coupled receptors, actin cytoskeleton, apical-basolateral polarity complexes and interactions with TJ-associated and AJ proteins. Integral TJ proteins (e.g., claudins) have not previously been shown to regulate Hippo signaling or YAP/TAZ activity. Preliminary studies demonstrate YAP/TAZ activation in C18 KO mice and association of YAP with C18 in wild type mice, leading us to hypothesize that C18 is a novel regulator of lung stem/progenitor cell homeostasis via modulation of YAP/TAZ subcellular localization/activity. The overall goal of this project is to investigate the role of C18 in regulating lung stem/progenitor cell homeostasis by addressing the following Specific Aims: 1) explore cellular mechanisms underlying lung phenotype of C18 KO mice: 2) investigate signaling mechanisms regulating stem/progenitor cell homeostasis in C18 KO mice; and, 3) characterize molecular mechanisms whereby C18 regulates YAP/TAZ signaling. Elucidation of mechanisms regulating lung stem/progenitor cell function and identification of novel pathways transducing growth-promoting signals from TJ to the nucleus have important implications for modulating stem/progenitor cell function and augmenting regeneration following lung injury.

 描述(由申请人提供)：干细胞/祖细胞的增殖和分化必须受到严格的调控，以保持正常器官功能所需的适当细胞数量，同时防止肿瘤发生。阐明调控体干/祖细胞动态平衡的机制是理解这些群体如何维持和激活以满足损伤后组织再生需求的关键。细胞间连接由紧密连接(TJ)、黏附连接(AJ)和桥粒组成，是细胞间黏附的部位。Claudins是调节细胞旁通透性的不可或缺的TJ蛋白。Claudin 18(C18)是肺泡上皮细胞中表达最高的Claudin家族成员之一。我们最近产生了C18基因敲除(KO)小鼠，表现出肺上皮对离子和溶质的通透性增加。有趣的是，C18 KO小鼠表现出可能的肺干/祖细胞(包括肺泡上皮II型(AT2)细胞)的扩增和增殖增加，并增加了肺(和胃)的大小，暗示完整的TJ蛋白(特别是C18)是新的调节因子。 上皮干/祖细胞动态平衡和器官大小。河马信号通路通过对增殖和凋亡的相反作用来调节干/祖细胞的功能、器官大小和再生。河马信号在体外介导接触性抑制细胞增殖，并通过磷酸化上游蛋白抑制下游同源转录辅助激活因子、YAP和带有PDZ结合基序的转录辅助激活因子(TAZ)的活性，从而限制体内组织的过度生长。河马信号的上游调控因子尚未得到很好的描述，但包括通过G蛋白偶联受体、肌动蛋白细胞骨架、顶端-基底外侧极性复合体以及与TJ相关蛋白和AJ蛋白的相互作用而产生的细胞外刺激。整合的TJ蛋白(例如，Claudins)以前没有被证明调节河马信号或YAP/TAZ的活性。初步研究表明，在C18KO小鼠中YAP/TAZ被激活，在野生型小鼠中YAP与C18相关，这使我们假设C18是一种通过调节YAP/TAZ亚细胞定位/活性来调节肺干/祖细胞动态平衡的新的调节因子。本项目的总体目标是通过解决以下特定目标来研究C18在调节肺干/祖细胞稳态中的作用：1)探索C18 KO小鼠肺表型的细胞机制：2)研究C18 KO小鼠调节干/祖细胞稳态的信号机制；以及3)表征C18调节YAP/TAZ信号的分子机制。阐明肺干/祖细胞功能的调控机制，识别新的途径将促生长信号从TJ传递到细胞核，对于调节肺损伤后干/祖细胞的功能和促进再生具有重要意义。