Role of Mucin in Lung Homeostasis and Pathophysiology

粘蛋白在肺稳态和病理生理学中的作用

• 批准号: 8819046
• 负责人: Christopher M Evans
• 金额: $ 40.21万
• 依托单位: UNIVERSITY OF COLORADO DENVER
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-08-01 至 2018-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8819046
• 关键词: Abbreviations; Acute; Affect; Allergens; Allergic; Allergic inflammation; Asthma; Automobile Driving; Biology; Breathing; Cell secretion; Charge; Data; Development; Disease; Disulfides; Economics; Enzymes; Figs - dietary; Fucose; Functional disorder; Gene Expression Regulation; Genes; Genetic; Glycoproteins; Goals; Goblet Cells; Health; Health Care Costs; Homeostasis; Human; Inflammation; Knock-out; Knockout Mice; Lung; Lung diseases; MUC5AC gene; MUC5B gene; Measures; Mediating; Mediator of activation protein; Modeling; Mouse Protein; Mucin 1 protein; Mucins; Mucociliary Clearance; Mucolytics; Mucous body substance; Mus; Muscle Contraction; Mutant Strains Mice; Obstruction; Oryza; Patients; Pattern; Personal Satisfaction; Plug-in; Polymers; Polysaccharides; Positioning Attribute; Production; Property; Proteins; Publishing; Relative (related person); Research; Respiratory physiology; Response to stimulus physiology; Risk; Role; Smooth Muscle; Structure; Surface; Testing; Time; Tissues; Transcript; Transgenic Mice; airway hyperresponsiveness; asthmatic patient; biophysical properties; differential expression; economic impact; gene therapy; glycosylation; health economics; improved; methacholine; mucus hypersecretion; novel strategies; overexpression; polymerization; prevent; public health relevance; response; viscoelasticity

DESCRIPTION (provided by applicant): Asthma has significant human health and economic impacts. Excessive mucus is an important cause of airflow obstruction in fatal asthma. It is also present in mild to moderate disease, but is poorly understood and treated. Mucus overproduction in asthma is associated with the dysregulated expression of two mucin glycoproteins - MUC5AC and MUC5B. Increased MUC5AC is a consistent finding, but MUC5B varies. It remains stably produced in some patients, but is strongly repressed in others (>90%), resulting in as much as 400-times more MUC5AC than MUC5B. This dichotomous expression pattern occurs in patients who display the strongest acute responses to the inhaled bronchoconstricting agent methacholine (MCh). This airway hyperreactivity (AHR) feature can be modeled in mice through allergen exposure. Knockout mice lacking Muc5ac are protected from AHR, indicating that it is a critical mediator of asthma-like airflow obstruction. Thus, determining specific mechanisms of MUC5AC-mediated AHR may reveal important mechanisms of obstruction and potential targets for improving airflow in asthma. As part of a long term goal of elucidating the functions of MUC5AC and MUC5B in the airways, Muc5ac and Muc5b knockout and overexpressing mice will be used to model dichotomous mucin expression in human asthma, and to test the specific effects of each mucin on the biophysical properties of mucus that promote obstruction. In addition to their differential expression, emerging data show that MUC5AC and MUC5B have distinct disulfide polymer structures. They also have specific glycosylation patterns: MUC5B is sialylated, MUC5AC is fucosylated. Fucosylation increases mucus viscoelasticity, and FUT2, the enzyme that catalyzes mucin �1,2-fucosylation, is associated with asthma exacerbation risk. Thus, the concept driving this proposal is that mucins with distinct polymer and glycan structures establish the obstructive potential of airway mucus. Accordingly, the proposed studies test the hypothesis that MUC5AC mediates AHR through specific disulfide and fucosylation mechanisms that cause obstruction by promoting mucus viscoelasticity. Three Specific Aims are proposed: 1) demonstrate that MUC5AC, but not MUC5B, mediates acute AHR in allergic mouse airways; 2) determine whether increased mucus viscoelasticity is caused by MUC5AC-specific polymerization and fucosylation; 3) determine whether MUC5AC disulfide and fucosylation-dependent viscoelastic properties are critical mechanisms of AHR and mucus plugging. Wild type and mucin mutant mice will be studied at baseline, and under conditions of allergic inflammation induced by Apergillus oryzae extract exposure. Lung function, mucociliary clearance, and mucus viscoelasticity will be measured. The effects of pharmacological, enzymatic, and genetic inhibition of polymerization and fucosylation will be determined. Successful completion of these studies will advance our mechanistic understanding of AHR, and could identify novel strategies to prevent obstruction while preserving airway defense in asthma and other lung diseases.

描述（由申请人提供）：哮喘对人类健康和经济有重大影响。粘液过多是致命性哮喘中气流阻塞的一个重要原因。它也存在于轻度至中度疾病中，但对哮喘中粘液过多的了解和治疗却很少。与两种粘蛋白糖蛋白 - MUC5AC 和 MUC5B 的表达失调有关，这是一致的发现，但 MUC5B 在某些患者中仍然稳定产生。在其他人 (>90%) 中受到强烈抑制，导致 MUC5AC 比 MUC5B 多 400 倍，这种二分表达模式发生在对吸入支气管收缩剂乙酰甲胆碱 (MCh) 表现出最强急性反应的患者中。 (AHR) 特征可以通过过敏原暴露在小鼠中进行建模，缺乏 Muc5ac 的敲除小鼠可以免受 AHR 影响，这表明它是一个关键因素。因此，确定 MUC5AC 介导的 AHR 的具体机制可能会揭示阻塞的重要机制和改善哮喘气流的潜在目标，作为阐明 MUC5AC 和 MUC5B 在哮喘中的功能的长期目标的一部分。 Muc5ac 和 Muc5b 敲除和过表达小鼠将用于模拟人类哮喘中的二分粘蛋白表达，并测试每种粘蛋白对生物物理特性的具体影响除了它们的差异表达之外，新出现的数据表明，MUC5AC 和 MUC5B 具有不同的二硫键聚合物结构，它们还具有特定的糖基化模式：MUC5B 被唾液酸化，MUC5AC 被岩藻糖基化，而 FUT2（酶）。催化粘蛋白 1,2-岩藻糖基化与哮喘恶化风险相关。该提议认为，具有不同聚合物和聚糖结构的粘蛋白具有气道粘液的阻塞潜力，因此，拟议的研究测试了 MUC5AC 通过特定的二硫键和岩藻糖基化机制介导 AHR 的假设，并提出了三个特定目标。 ：1) 证明 MUC5AC 而不是 MUC5B 介导过敏性小鼠气道中的急性 AHR；2) 确定粘液粘弹性是否增加； 3）确定MUC5AC二硫化物和岩藻糖基化依赖性粘弹性特性是否是AHR和粘液堵塞的关键机制，将在基线和由MUC5AC诱导的过敏性炎症条件下进行研究。将测量米曲霉提取物的肺功能、粘液纤毛清除率和粘液粘弹性的影响。聚合和岩藻糖基化的基因抑制将得到确定，这些研究的成功完成将促进我们对 AHR 机制的理解，并可能确定预防阻塞同时保持哮喘和其他肺部疾病气道防御的新策略。