Role of Airway Epithelium in Mycoplasma Pathogenesis

粘液高分泌是囊性纤维化、哮喘和慢性阻塞性肺疾病的主要临床症状。其结果是在小呼吸道形成粘液堵塞，这是反复感染的部位。这些塞子还会导致氧气不足。上述每种情况的致命性都与过量粘液的存在直接相关。高分泌的底物是呼吸道粘液腺的病理生长，这反映在这些患者尸检中持续存在的腺壁比增加。分子 启动成人呼吸道腺体生长的机制尚不清楚，但一旦了解，可能会为帮助这些患者的药物开发开辟道路。根据我们的初步数据及其与其他系统中的发现的相似性，我们认为支原体在上皮间充质连接处引起刺激的趋同，导致Lef-1/β连环蛋白的过度表达，并随后在选定的上皮细胞中发生基因表达的变化。受影响的基因包括E-钙粘蛋白和EMMPRIN。虽然E-钙粘附素的下调通过削弱贴壁连接促进了芽的形成，但根据我们的体外观察，EMMPRIN的上调可以增加非贴壁细胞的运动性。 在目标1中，我们将在体外和体内使用针对每种蛋白的选择性siRNA来研究腺芽形成对Lef-1、βcatenin、WNT和EMMPRIN的依赖。在目标2中，我们将检验这样的假设，即腺芽中Lef-1/β连环蛋白的上调直接导致EMMPRIN的上调，EMMPRIN的启动子确实包含假定的Lef1-β连环蛋白反应元件。在目标3中，我们将确定EMMPRIN过度表达的上皮细胞中与过度运动表型有关的分子变化。拟议的研究结果应该为肺部疾病中粘液腺的形成提供一个分子模型，并为开发阻断高分泌和延长生命的药物提供新的靶点。

Mucus hypersecretion is a major clinical symptom of cystic fibrosis, asthma, and COPD. A consequence is the formation of mucus plugs in small airways, which are sites of recurrent infection. These plugs also bring about oxygen insufficiency. The lethality of each of the above conditions is directly linked to the presence of excessive mucus. The substrate for hypersecretion is the pathological growth of airway mucus glands, which is reflected in increased gland:wall ratios consistently found at autopsy in these patients. The molecular mechanisms responsible for initiating gland growth in adult airways are unknown, but once understood, could open the way for drug development to help these patients. Based on our preliminary data and its similarity to findings in other systems, we propose that Mycoplasma elicits a convergence of stimuli at epithelial mesenchymal junctions leading to Lef-1/beta catenin overexpression and subsequent changes in gene expression in select epithelial cells. Among the genes so affected are E-cadherin and EMMPRIN. While downregulation of E-cadherin promotes bud formation by weakening adherens junctions, upregulation of EMMPRIN can be expected, based on our in vitro observations, to increase motility of the non-adherent cells. In Aim 1, we will examine the dependence of gland bud formation on Lef-1, beta catenin, wnt and EMMPRIN, using selective siRNAs directed against each protein both in vitro and in vivo. In Aim 2, we will test the hypothesis that Lef-1/beta catenin upregulation in gland buds is directly responsible for upregulation of EMMPRIN, whose promoter indeed contains putative Lef1-beta catenin response elements. In Aim 3, we will identify the molecular changes in EMMPRIN-overexpressing epithelial cells contributing to the hypermotile phenotype. The results of the proposed studies should provide a molecular model of mucus gland formation in lung disease and suggest novel targets for the development of drugs to block hypersecretion and prolong life.