Mucin sialylation drives epithelial cell senescence and severe asthma

本申请探讨了范式转换假说，即蛋白质的翻译后修饰（唾液酸化）， 细胞表面粘蛋白MUC 4驱动气道上皮细胞的终末分化和衰老 通过抑制表皮生长因子受体（EGFR）家族途径，恶化上皮细胞 伤口修复和哮喘严重程度。我们提出的研究将是第一个专门测试系留粘蛋白， 它们的翻译后N-糖基化/唾液酸化在AEC终末分化和衰老中起作用。我们 公开的数据（Zhou等）证明栓系粘蛋白MUC 4 β，即，MUC 4 α βSA，对照 杯状细胞终末分化作为β-半乳糖苷α 2，6-唾液酸转移酶-1（ST 6 GAL 1）活性的函数。 ST 6 GAL 1和MUC 4 β均严重降低AEC增殖能力，具有额外的公开数据（Inoue et al）将减少的AEC增殖与体外异常伤口修复联系起来。AEC增殖能力降低 可能反映了EGFR家族成员ErbB 2（一种已知的MUC 4 β受体）的活化减少。新数据 证实MUC 4和ST 6 GAL 1升高存在于重度急性发作倾向性哮喘和室内哮喘患者中， 尘螨攻击的小鼠。两者的升高在生物学上与细胞内谷胱甘肽（GSH）的降低有关， 氧化型谷胱甘肽（GSSG）比率（氧化应激）和较低的线粒体和衰老基因表达。 平行的体外AEC数据显示T2炎症/IL-13改变细胞内代谢和线粒体， 降低GSH/GSSG，并进一步降低伤口修复。然而，MUC 4 β和/或其 唾液酸化对上皮细胞表型、细胞衰老以及这些变化的作用机制 严重哮喘还不清楚。本文提出的研究将全面评估以下方面的交叉点： 粘蛋白、粘蛋白唾液酸化和衰老途径，同时使用 原代人AEC细胞培养物和转基因小鼠模型。这三个拟议目标将：1）阐明 MUC 4 β和MUC 4 βSA对AEC终末分化、衰老和凋亡的机制和功能影响 体外伤口修复，2）测试Muc 4 βSA-AEC相互作用对粘蛋白分泌、杯状细胞 在哮喘小鼠模型中的增生/终末分化、衰老和伤口修复，以及3）定义 哮喘患者MUC 4 βSA与衰老和AEC表型的关系这些共同的目标 将反复开发数据，将粘蛋白，其唾液酸化和基本的衰老相关上皮细胞 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.