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（适用提供）：哮喘具有重大的人类健康和经济影响。过度粘液是致命哮喘气流反对的重要原因。它也存在于轻度至中度疾病中，但知之甚少和治疗。哮喘中的粘液过量生产与两种粘蛋白糖蛋白-MUC5AC和MUC5B的表达失调有关。 MUC5AC增加是一个一致的发现，但MUC5B各种。它仍然在某些患者中牢固地产生，但在其他患者中受到强烈抑制（> 90％），导致MUC5AC的MUC5AC高400倍。这种二分表达模式发生在对遗传支气管收缩剂方法（MCH）的强烈急性反应的患者中。该气道高反应性（AHR）特征可以通过过敏原暴露在小鼠中建模。缺乏MUC5AC的敲除小鼠免受AHR的保护，表明它是类似哮喘的气流对象结构的关键介体。这是确定MUC5AC介导的AHR的特定机制可能揭示物体构建的重要机制和改善哮喘气流的潜在目标。作为阐明MUC5AC和MUC5B在气道中的功能的长期目标的一部分，MUC5AC和MUC5B敲除和过表达的小鼠将用于模拟人哮喘中二分法粘蛋白的表达，并测试每种粘蛋白对伴有粘液物质的特定作用的特定作用。除了它们的差异表达外，新兴数据还表明，MUC5AC和MUC5B具有不同的二硫化物聚合物结构。它们还具有特定的糖基化模式：MUC5B被溶解，MUC5AC是偶联的。岩藻糖基化增加了粘液粘弹性，而FUT2（催化粘蛋白-1,2-葡萄糖基化的酶）与哮喘恶化风险有关。这是推动该建议的概念是，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性潜力。根据彼此，提出的研究检验了MUC5AC通过特定的二硫键和岩藻糖基化机制介导AHR的假设，该机制通过促进粘液粘弹性而导致阻塞。提出了三个具体目的：1）证明MUC5AC而非MUC5B介导过敏小鼠气道中的急性AHR； 2）确定粘液粘弹性增加是否是由MUC5AC特异性聚合和构造化引起的； 3）确定MUC5AC二硫化物和岩藻糖基化依赖性粘弹性是否是AHR和粘液塞的关键机制。野生型和突变小鼠将在基线时进行研究，并在因过敏性炎症的条件下由Apergillus oryzae提取物暴露。将测量肺功能，粘膜缩减清除率和粘液粘弹性。将确定药理，酶促和遗传抑制聚合和构造的影响。这些研究的成功完成将提高我们对AHR的机械理解，并可以确定在保留哮喘和其他肺部疾病中气道防御的新型策略。