Munc18 Proteins in Airway Mucus Hypersecretion

描述（由申请人提供）： 气道粘液形成一层保护层，防止吸入颗粒和病原体。然而，响应于炎症刺激的过度粘液分泌可导致气流阻塞。粘液分泌过多可以分为两个不同的阶段：上皮层的化生，主要由纤毛细胞和克拉拉细胞组成的层，主要由分泌粘液的杯状细胞组成;这是其次是调节分泌的粘液从化生上皮。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;细胞外机制的组分;以及连接细胞外分泌信号与细胞外膜融合的信号转导途径。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。Munc 18蛋白是分泌细胞的胞吐机制的普遍存在的组分。它们的缺失导致分泌的完全失败，并且它们的过表达也损害分泌。总之，这些数据表明Munc 18蛋白发挥的关键作用，并表明它们的表达受到严格调控。我们发现Munc 18 B在小鼠气道上皮化生中高度上调，其启动子区含有已知对炎症刺激有反应的元件。我们建议抑制Munc 18 B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和病理生理作用，并分析小鼠和人类中Munc 18 B表达的控制，以深入了解粘液化生的分子发病机制。目的1：进一步表征Munc 18蛋白在小鼠和人细胞中调节气道粘液分泌的细胞生物学。目标二：通过减少Munc 18 B表达，降低气道杯状细胞分泌粘液的能力，分析粘液高分泌在过敏性哮喘和细菌性肺炎小鼠模型中的保护作用和病理生理作用。目标3：确定小鼠气道上皮化生中控制Munc 18 B基因表达的关键顺式作用DNA元件和转录因子。目标4：确认顺式作用DNA元件和转录因子在人类气道分泌性化生中控制Munc 18 B基因表达的重要性。

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.