Munc18 Proteins in Airway Mucus Hypersecretion

描述(由申请人提供)： 呼吸道粘液形成一层保护层，防止吸入的颗粒和病原体。然而，对炎症刺激的过度粘液分泌可导致气流阻塞。粘液高分泌可分为两个不同的阶段：上皮化生，主要由纤毛细胞和Clara细胞组成，化生上皮层主要由分泌粘液的杯状细胞组成；其次是从化生上皮调节粘液分泌。在分子水平上，分泌性化生涉及编码三组蛋白质的基因的表达：分泌产物；胞外机制的组成部分；以及连接细胞外分泌信号和胞膜融合的信号转导通路。分泌的大分子和信号转导途径是深入研究的主题，但对胞外机制知之甚少。Munc18蛋白是分泌细胞胞吐机制中普遍存在的成分。它们的缺乏会导致分泌的完全失败，而它们的过度表达也会损害分泌。综上所述，这些数据表明了Munc18蛋白的关键作用，并表明它们的表达受到严格调控。我们已经发现Munc18B在小鼠的化生呼吸道上皮中高度上调，并且它的启动子区域包含已知对炎症刺激做出反应的元件。我们建议抑制Munc18B的表达，以测试粘液分泌在小鼠过敏性和感染性肺部炎症模型中的保护作用和病理生理作用，并分析Munc18B在小鼠和人类中的表达调控，以深入了解粘液化生的分子发病机制。目的1：进一步研究Munc18蛋白在调节小鼠和人细胞呼吸道粘液分泌中的细胞生物学特性。目的：通过降低Munc18B的表达，降低小鼠气道杯状细胞分泌黏液的能力，分析黏液高分泌在过敏性哮喘和细菌性肺炎模型中的保护作用和病理生理作用。目的3：鉴定控制Munc18B基因在小鼠上皮化生中表达的关键顺式作用DNA元件和转录因子。目的：证实控制Munc18B基因表达的顺式作用DNA元件和转录因子在人类呼吸道分泌性化生中的重要性。

DESCRIPTION (provided by applicant): Airway mucus forms a protective layer against inhaled particles and pathogens. However, excessive mucus secretion in response to inflammatory stimuli can lead to airflow obstruction. Mucus hypersecretion can be divided into two distinct stages: metaplasia of an epithelial layer that consists predominantly of ciliated and Clara cells into a layer that consists predominantly of mucus-secreting goblet cells; this is followed by regulated secretion of mucus from the metaplastic epithelium. At a molecular level, secretory metaplasia involves expression of genes encoding three sets of proteins: secretory products; components of an exocytic machinery; and signal transduction pathways connecting extracellular secretory signals to exocytic membrane fusion. Secreted macromolecules and signal transduction pathways are subjects of intensive study, but little is known about the exocytic machinery. Munc18 proteins are ubiquitous components of the exocytic machinery of secretory cells. Their absence leads to a complete failure of secretion, and their overexpression also impairs secretion. Together, these data indicate the critical role played by Munc18 proteins and suggest that their expression is tightly regulated. We have found that Munc18B is highly upregulated in metaplastic airway epithelium of mice, and that its promoter region contains elements known to respond to inflammatory stimuli. We propose to suppress expression of Munc18B to test the protective and pathophysiologic roles of mucus secretion in models of allergic and infectious lung inflammation in mice, and to analyze the control of Munc18B expression in mice and humans to gain insight into the molecular pathogenesis of mucus metaplasia. Aim 1: Further characterize the cellular biology of Munc18 proteins in the regulation of airway mucus secretion in murine and human cells. Aim 2: Analyze the protective and pathophysiologic roles of mucus hypersecretion in murine models of allergic asthma and bacterial pneumonia by reducing the capability of airway goblet cells to secrete mucus through reduction of Munc18B expression. Aim 3: Identify critical cis-acting DNA elements and transcription factors that control expression of the Munc18B gene in metaplastic airway epithelium of mice. Aim 4: Confirm the importance of cis-acting DNA elements and transcription factors that control expression of the Munc18B gene in airway secretory metaplasia of humans.