Role of Mucin in Lung Homeostasis and Pathophysiology

项目摘要/摘要 虽然粘液是一种防御屏障，对维持健康的肺部至关重要，但过量的粘液是一种重要的 肺部疾病的病理因素。粘液功能和功能障碍的不同面孔集中体现了 需要严格控制呼吸道粘液中的主要大分子--聚合粘蛋白MUC5AC和 MUC5B。在哮喘中，粘液粘弹性增加并引起气流和粘液纤毛清除(MCC)。 没有得到充分治疗的损伤。我们假设，通过确定特定的分子机制， MUC5AC和MUC5B的生物合成，我们将确定新的机制和潜在的治疗方法来改进 呼吸道粘液功能和功能障碍。我们之前演示了Muc5ac和MUC5B的重要功能 在基因敲除的小鼠中。现在，我们将探讨MUC5AC和MUC5B作为聚合物的功能。MUC5AC和MUC5B 通过分子间二硫键在其富含半胱氨酸的羧基(C-)和氨基(N-)末端组装，导致 形成大量的糖共聚物。最近，我们用吸入剂治疗过敏性炎症小鼠 破坏了粘蛋白聚合物的硫键，我们发现粘液的粘弹性、MCC和气流都有功能 改进了。虽然吸入粘液药物可能有用，但目前还没有安全或有效的选择来治疗 治疗用途。因此，进一步需要确定MUC5AC和MUC5B亚型的特定聚合物功能。 我们假设粘液的功能和功能障碍是由特定的粘蛋白亚型表达和 二硫化物聚合机制，调节粘液的粘弹性凝胶和传输特性。我们将测试 具体目标如下：1)亚型特异性粘蛋白聚合物介导AHR和MCC；2) 聚合是由N-端和C-端保守的半胱氨酸残基之间的二硫键介导的 MUC5AC/Muc5ac和MUC5B/MUC5B；3)粘蛋白需要保守的N-末端和C-末端半胱氨酸 体内异构体专一性聚合和功能。我们将在粘蛋白突变的小鼠和人类身上进行研究 粘液样本，在呼吸道上皮细胞培养中，以及使用生物工程人类小气道芯片设备。 成功完成这里提出的目标将进一步促进我们对粘蛋白聚合物的理解 在呼吸道中的形成和功能。我们的研究还可以确定预防梗阻的改进策略 同时保留肺部健康所需的防御性粘液功能。

PROJECT SUMMARY/ABSTRACT Although mucus is a defensive barrier that is critical for maintaining healthy lungs, excessive mucus is a significant pathological contributor to lung diseases. The disparate faces of mucus function and dysfunction epitomize the need for tightly controlling the predominant macromolecules in airway mucus - the polymeric mucins MUC5AC and MUC5B. In asthma, mucus viscoelasticity increases and causes airflow and mucociliary clearance (MCC) impairments that are not adequately treated. We postulate that by determining specific molecular mechanisms of MUC5AC and MUC5B biosynthesis, we will identify novel mechanisms and potential treatments for improving airway mucus function and dysfunction. We previously demonstrated significant functions for Muc5ac and Muc5b in knockout mice. We now seek to interrogate how Muc5ac and Muc5b function as polymers. Muc5ac and Muc5b assemble by inter-molecular disulfide bonding at their cysteine-rich carboxyl (C-) and amino (N-) termini, resulting in the formation of massive glycopolymers. Recently, we treated allergically inflamed mice with inhaled agents that disrupted mucin polymer disulfide bonds, and we found that mucus viscoelasticity, MCC, and airflow function all improved. While inhaled mucolytics could be useful, there are currently no safe or effective options available for therapeutic use. Thus, there is further need to determine MUC5AC and MUC5B isoform specific polymer functions. We hypothesize that mucus function and dysfunction are dictated by specific mucin isoform expression and disulfide polymerization mechanisms that regulate mucus viscoelastic gel and transport properties. We will test the following hypotheses in thee Specific Aims: 1) that isoform specific mucin polymers mediate AHR and MCC; 2) that polymerization is mediated by disulfide bonds between conserved cysteine residues in the N- and C-termini of MUC5AC/Muc5ac and MUC5B/Muc5b; and 3) that conserved N- and C-terminal cysteines are required for mucin isoform-specific polymerization and function in vivo. We will conduct studies in mucin mutant mice, in human mucus samples, in airway epithelial cell cultures, and with bioengineered Human Small Airway-on-a-Chip devices. Successful completion of the Aims proposed here will further advance our understanding of mucin polymer formation and function in the airways. Our studies could also identify improved strategies for preventing obstruction while preserving defensive mucus functions that are required for lung health.