Role of MUC5AC Mucins in Airway Disease

性状（由申请方提供）：分泌性粘蛋白糖蛋白是肺粘液的主要大分子组分，其覆盖并保护呼吸道。粘蛋白在急性和慢性肺病中分泌过多和过度产生，从而导致气道中的粘液阻塞以及哮喘和其他慢性阻塞性肺病患者的疾病发病率和死亡率。MUC 5AC是一种主要的气道粘蛋白，定位于传导气道上皮的杯状细胞，并且在哮喘气道中过表达。我们的长期目标是在分子水平上更好地确定MUC 5AC粘蛋白基因表达的激活和抑制之间的联系，以便为开发新的药物以规避粘蛋白过度生产提供更好的基础。MUC 5AC基因可以在肺细胞中以病理学和免疫学相关的方式被转录激活（IL-1？）或抑制（Dex）。然而，很少有人知道的机制，调节粘蛋白基因顺式阻遏，这可能涉及重塑染色质，更高水平的基因调控，或有关染色质修饰粘蛋白基因。在本申请中，我们将关注Dex介导的染色质重塑在MUC 5AC基因表达的顺式抑制中的作用，以及IL-1？诱导的染色质修饰在上调MUC 5AC基因表达中的作用。我们将在三个目标中研究肺细胞中这些事件的潜在机制。将在分化的NHBE细胞和A549细胞中进行体外评价，并在过敏性哮喘小鼠模型和人体组织中进行体内评价。在目标1中，我们将在染色质水平上表征GR诱导的MUC 5AC顺式抑制，以检验Dex通过染色质重塑顺式抑制MUC 5AC基因表达的假设。在目标2中，我们将描述IL-1？诱导的MUC 5AC基因激活，以检验MUC 5AC基因属于一类具有可调控和晚期可及性启动子的基因的假设，例如，需要刺激依赖性修饰染色质结构以使转录因子位点可用于转录的启动子。在目标3中，我们将确定炎症介质（IL-1？）和抗炎剂（Dex）是否介导对暴露于两种介质的肺细胞中MUC 5AC染色质结构的相反作用。这将最终影响炎症性肺病的皮质类固醇治疗期间MUC 5AC粘蛋白的产生。公共卫生相关性。粘蛋白在慢性肺病中分泌过多和过度产生，从而导致气道中的粘液阻塞以及哮喘和其他慢性阻塞性肺病患者的疾病发病率和死亡率。MUC 5AC是一种主要的肺粘蛋白，在哮喘气道中过度产生。MUC 5AC基因在肺细胞中以病理学和免疫学相关的方式被转录激活（IL-1？）或抑制（Dex）。了解糖皮质激素抑制MUC 5AC基因表达的机制将有助于理解为什么类固醇维持在减少严重哮喘患者急性发作的数量和严重程度方面很重要，并且对于制定粘蛋白过度产生的肺部疾病的治疗干预措施至关重要。

DESCRIPTION (provided by applicant): Secretory mucin glycoproteins are the major macromolecular component of lung mucus, which coats and protects the respiratory tract. Mucins are hypersecreted and overproduced in acute and chronic lung disease, thereby contributing to mucus obstruction in the airways and to disease morbidity and mortality in patients with asthma and other chronic obstructive pulmonary diseases. MUC5AC, one of the major airway mucins, is localized to goblet cells in the conducting airway epithelium, and is overexpressed in asthmatic airways. Our long term objective is to better define the link between activation and repression of MUC5AC mucin gene expression at the molecular level in order to provide a better foundation for developing novel pharmaceutical agents to circumvent mucin overproduction. The MUC5AC gene can be transcriptionally activated (IL-1¿) or repressed (Dex) in lung cells in a pathologically and pharmacologically relevant fashion. However, little is known about mechanisms that regulate mucin gene cis-repression, which likely involve remodeling of chromatin, a higher level of gene regulation, or about chromatin modification of mucin genes. In this application, we will focus on Dex-mediated chromatin remodeling in cis- repression of MUC5AC gene expression and on IL-1¿-induced chromatin modifications in upregulating MUC5AC gene expression. We will investigate mechanisms underlying these events in lung cells in three Aims. They will be evaluated in vitro in differentiated NHBE cells and A549 cells and in vivo in a murine model of allergic asthma and in human tissue. In Aim 1 we will characterize the GR-induced cis-repression of MUC5AC at the chromatin level to test the hypothesis that Dex cis-represses MUC5AC gene expression by chromatin remodeling. In Aim 2 we will characterize the IL-1¿-induced activation of the MUC5AC gene to test the hypothesis that the MUC5AC gene belongs to a class of genes with promoters with regulated and late accessibility, e.g. promoters that require stimulus-dependent modifications in chromatin structure to make transcription factors sites accessible for transcription. In Aim 3 we will determine whether inflammatory mediators (IL-1¿) and anti-inflammatory agents (Dex) mediate opposing effects on MUC5AC chromatin structure in lung cells exposed to both mediators. This would ultimately impact on MUC5AC mucin production during corticosteroid treatment of inflammatory lung disease. PUBLIC HEALTH RELEVANCE. Mucins are hypersecreted and overproduced in chronic lung disease, thereby contributing to mucus obstruction in the airways and to disease morbidity and mortality in patients with asthma and other chronic obstructive pulmonary diseases. MUC5AC is a major lung mucin and is overproduced in asthmatic airways. The MUC5AC gene has been shown to be transcriptionally activated (IL-1¿) or repressed (Dex) in lung cells in a pathologically and pharmacologically relevant fashion. Understanding the mechanisms whereby MUC5AC gene expression is repressed by glucocorticoids will prove useful in understanding why steroid maintenance is important in reducing the number and severity of exacerbations in severe asthmatic patients and is fundamental for formulating therapeutic interventions in lung diseases with mucin overproduction.