Mucin sialylation drives epithelial cell senescence and severe asthma

这个应用程序探索了范式转换假设，即翻译后修饰(唾液酸化) 细胞表面粘蛋白，MUC4，驱动呼吸道上皮细胞的终末分化和衰老 (AECS)通过抑制表皮生长因子受体(EGFR)家族通路，使上皮恶化 伤口修复和哮喘严重程度。我们提议的研究将是第一个专门测试系留粘蛋白和 其翻译后N-糖基化/唾液酸化在AEC终末分化和衰老中的作用。我们的 已发表的数据(周等人)证明系留粘蛋白MUC4β，即MUC4αβSA的唾液酸化控制 杯状细胞的终末分化与β-半乳糖苷α2，6-唾液酸转移酶-1(ST6GAL1)活性有关。 ST6GAL1和MUC4β都严重降低了血管内皮细胞的增殖能力，并公布了更多的数据(井上等人 A1)AEC增殖减少与体外创面异常修复有关。AEC增殖能力降低 可能反映了表皮生长因子受体家族成员ErbB2的激活减少，ErbB2是MUC4β的已知受体。新数据 确认MUC4和ST6GAL1的升高在严重的易加重哮喘和室内存在 尘螨对小鼠构成了挑战。两者在生物学上都与低细胞内谷胱甘肽(GSH)相关 氧化谷胱甘肽(GSSG)比率(氧化应激)以及降低线粒体和衰老基因的表达。 平行的体外AEC数据显示T2炎症/IL-13改变了细胞内代谢和线粒体， 降低GSH/GSSG，进一步降低伤口修复。然而，MUC4β和/或其 唾液酸化对上皮细胞表型、细胞衰老的影响及其作用机制 严重哮喘的原因尚不清楚。这里提出的研究将全面评估 粘蛋白、粘蛋白唾液酸化和衰老途径(S)，同时使用 原代培养人血管内皮细胞和转基因小鼠模型。提出的三个目标将：1)阐明 MUC4β和MUC4βSA对血管内皮细胞终末分化、衰老和功能的影响 2)检测MUC4-βSA-AEC相互作用对粘蛋白分泌、杯状细胞功能的影响 哮喘小鼠模型中的增殖/终末分化、衰老和伤口修复，3)定义 哮喘患者MUC4AECSA与衰老及β表型的关系这些同时存在的目标 将反复开发将粘蛋白及其唾液酸化与基本衰老相关的上皮细胞联系起来的数据 确定治疗严重哮喘的高度新颖靶点的过程。

This application explores the paradigm shifting hypothesis that post-translational modification (sialylation) of a cell surface (tethered) mucin, MUC4, drives terminal differentiation and senescence of airway epithelial cells (AECs) through inhibition of epidermal growth factor receptor (EGFR) family pathways, worsening epithelial wound repair and asthma severity. Our proposed studies will be the first to specifically test tethered mucins and their post-translational N-glycosylation/sialylation for a role in AEC terminal differentiation and senescence. Our published data (Zhou et al) demonstrate that sialylation of the tethered mucin, MUC4β, i.e., MUC4α βSA, controls goblet cell terminal differentiation as a function of β-galactoside α2,6-sialyltransferase-1 (ST6GAL1) activity. Both ST6GAL1 and MUC4β critically lower AEC proliferative capacity, with additional published data (Inoue et al) linking diminished AEC proliferation to abnormal wound repair in vitro. Reduced AEC proliferative capacity may reflect reduced activation of the EGFR family member, ErbB2, a known receptor for MUC4β. New data confirm that elevations in MUC4 and ST6GAL1 are present in severe exacerbation-prone asthma and in house dust mite challenged mice. Elevations in both biologically associate with low intracellular glutathione (GSH) to oxidized glutathione (GSSG) ratios (oxidative stress) and lower mitochondrial and senescence gene expression. Parallel in vitro AEC data show T2 inflammation/IL-13 alters intracellular metabolism and mitochondria, decreases GSH/GSSG, and further decreases wound repair. Yet, the overall impact of MUC4β and/or its sialylation to epithelial cell phenotypes, cell senescence, and the mechanisms by which these changes contribute to severe asthma are unclear. The studies proposed here will comprehensively evaluate the intersection of mucins, mucin sialylation, and senescence pathway(s), while robustly testing their functional importance using primary human AEC cell cultures and transgenic mouse models. The three proposed aims will: 1) elucidate the mechanistic and functional impact of MUC4β and MUC4βSA on AEC terminal differentiation, senescence and wound repair in vitro, 2) test the functional impact of Muc4βSA-AEC interactions on mucin secretion, goblet cell hyperplasia/terminal differentiation, senescence, and wound repair in an asthma mouse model and 3) define the relationship of MUC4βSA to senescence and AEC phenotypes in human asthma patients. These concurrent aims will iteratively develop data that link mucins, their sialylation and fundamental senescence-related epithelial processes to identify highly novel targets for treatment of severe asthma.