Transcriptional Control of Submucosal Gland Formation and Function

描述（由申请人提供）：呼吸道不断暴露于微生物病原体和颗粒中，但受到多层宿主防御系统的保护，该系统用于维持肺功能和无菌。常见的慢性肺部疾病，包括囊性纤维化（CF）、慢性阻塞性肺疾病和哮喘，伴随着粘膜纤毛清除、粘液产生和宿主防御的严重缺陷。这些疾病伴有粘液化生、粘液分泌过多或浓稠、炎症和肺部感染易感性。该应用旨在确定与CF患者肺部疾病相关的粘膜纤毛清除缺陷的分子机制。这项工作基于以下初步数据：1)一个新的转录因子网络，该网络决定发育中的气管和支气管内的气道上皮细胞（AECs）的模式和分化，以及分泌大部分液体、电解质的粘膜下腺（smg）的形成。2)囊性纤维化跨膜传导调节剂（CFTR）的缺乏会影响AECs和smg的模式、生长、分化和基因表达。该应用将验证PAX9和相关转录网络在发育和成熟气道中AEC和SMG形态发生和功能调控中起关键作用的假设。本研究将利用转基因小鼠，在体内和体外有条件地删除或添加PAX9和与PAX9相关的基因到发育和成熟的气道上皮中。PAX9和相关蛋白调控AEC和SMG形成和功能的关键基因和过程的分子和细胞机制将被评估。提出的pax9依赖性调控程序在CF肺并发症发病机制中的作用将在cftr缺陷猪和小鼠中确定。本研究旨在确定AEC和SMG形态发生的细胞和分子基础，以及与毛粘清除缺陷引起的复发性感染发病机制相关的功能。

DESCRIPTION (provided by applicant): The respiratory tract is constantly exposed to microbial pathogens and particles, but is protected by a multitiered host defense system that serves to maintain lung function and sterility. Severe defects in mucociliary clearance, mucus production, and host defense accompany common chronic lung diseases, including cystic fibrosis (CF), chronic obstructive pulmonary disease, and asthma. These disorders are complicated by mucus metaplasia, mucus hyperproduction or inspissation, inflammation, and susceptibility to pulmonary infection. This application seeks to determine the molecular mechanisms underlying deficits in mucociliary clearance associated with pulmonary disease in CF. The work is based on preliminary data demonstrating 1) a novel network of transcription factors that determines both the patterning and differentiation of airway epithelial cells (AECs) lining the developing trachea and bronchi, and the formation of submucosal glands (SMGs) that secrete the majority of fluids, electrolytes, and host defense proteins onto the airway surface and 2) that patterning, growth, diferentiation, and gene expression of AECs and SMGs are influenced by the lack of Cystic Fibrosis Transmembrane Conductance Regulator (CFTR). This application will test the hypothesis that PAX9 and an associated transcriptional network play a critical role in the regulation of AEC and SMG morphogenesis and function in the developing and mature airway. This proposal will utilize transgenic mice in which PAX9 and genes associated with PAX9 are conditionally deleted or added to the developing and mature airway epithelium in vivo and in vitro. The molecular and cellular mechanisms by which PAX9 and associated proteins regulate genes and processes critical for AEC and SMG formation and function wil be assessed. The role of the proposed PAX9-dependent regulatory program in the pathogenesis of the pulmonary complications of CF will be determined in CFTR-deficient pigs and mice. This proposal seeks to determine the cellular and molecular basis underlying AEC and SMG morphogenesis and function relevant to the pathogenesis of recurrent infections caused by defects in mucociliary clearance. PUBLIC HEALTH RELEVANCE: Throughout life, the lung is exposed to particles, bacteria, viruses, and other microbial pathogens and toxicants that must be removed from the lung by a mucociliary "escalator." Common, chronic lung diseases, including asthma, chronic obstructive lung disease, and cystic fibrosis (CF) are complicated by mucus hyperproduction and recurrent lung infections, leading to long-term disability and mortality affecting millions of individuals world- wide. This application will identify the mechanisms regulating submucosal gland differentiation and function leading to abnormal airway mucociliary clearance and infection. The grant will identify the processes controlling gene expression that are associated with abnormal submucosal gland formation and function in CF and that are also relevant to the pathogenesis of chronic lung diseases in general. Understanding the processes controlling airway epithelial and submucosal gland function provides a framework for the development of new therapies for chronic lung diseases.