Mucin biosynthesis - Epidermal growth factor downregulates core 2 enzymes in a human airway adenocarcinoma cell line
Mucin biosynthesis - Epidermal growth factor downregulates core 2 enzymes in a human airway adenocarcinoma cell line
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DOI：
10.1165/rcmb.2002-0147oc
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发表时间：
2003-07-01
影响因子：
6.4
通讯作者：
Cheng, PW
中科院分区：
文献类型：
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作者：
Beum, PV;Bastola, DR;Cheng, PW
表现出核心2 β 1，6 N-乙酰葡糖胺基转移酶（C2 GnT）活性的酶在包括炎症反应和免疫系统功能的生理过程中起重要作用，并且C2 GnT活性在诸如T细胞活化和细胞分化的过程中受到调节。在这项研究中，我们研究了C2 GnT活性的调节H292气道上皮细胞系的表皮生长因子（EGF），这已被证明是上调表达的气道粘蛋白MUCSAC在这个细胞系。我们发现EGF以时间和剂量依赖性方式抑制C2 GnT活性，并且还抑制核心4 PI，6 N-乙酰葡糖胺转移酶（C4 GnT）活性。与C4 GnT活性的抑制一致，北方印迹结果显示EGF优先抑制C2 GnT的M亚型，其形成核心2、核心4和血型I β 1，6分支碳水化合物结构，而仅形成核心2结构的L亚型仅受到适度影响。此外，EGF处理导致细胞中表达的FLAG标记的MUC 1的碳水化合物结构从基于核心2的结构向基于核心I的结构转变，这与EGF对C2 GnT的抑制作用一致。转化生长因子α模拟EGF对C2 GnT的作用，暗示EGF受体（EGF-R）参与C2 GnT抑制，EGF-R酪氨酸激酶抑制剂AG 1478阻断C2 GnT抑制，证实EGF-R在抑制C2 GnT表达中的作用。此外，PD 98059，一种特异性的丝裂原活化蛋白激酶/细胞外信号调节激酶激酶（MEK）1/2的Ras-丝裂原活化蛋白激酶途径的抑制剂，完全阻断EGF的抑制作用，这表明Ras-丝裂原活化蛋白激酶途径可能参与EGF介导的C2 GnT下调。这项研究的结果表明，气道细胞暴露于EGF可能导致粘蛋白碳水化合物结构的重塑，可能改变细胞的生物学特性。
Enzymes which exhibit core 2 beta1,6 N-acetylglucosaminyltransferase (C2GnT) activity play important roles in physiologic processes including the inflammatory response and immune system function, and C2GnT activity is regulated during processes, such as T cell activation and cellular differentiation. In this study, we have examined the regulation of C2GnT activity in the H292 airway epithelial cell line by epidermal growth factor (EGF), which has been previously shown to upregulate expression of the airway mucin MUCSAC in this cell line. We found that EGF suppressed C2GnT activity in a time- and dose-dependent fashion, and also suppressed core 4 PI,6 N-acetylglucosaminyltransferase (C4GnT) activity. Consistent with the suppression of C4GnT activity, Northern blotting results showed that EGF preferentially inhibited the M isoform of C2GnT, which forms core 2, core 4, and blood group I beta1,6 branched carbohydrate structures, while the L isoform, which forms only the core 2 structure, was only modestly affected. Furthermore, EGF treatment resulted in a shift in the carbohydrate structure of FLAG-tagged MUC1 expressed in the cells from core 2-based toward core I-based structures, consistent with the inhibitory effects of EGF on C2GnT. Transforming growth factor alpha mimicked the effect of EGF on C2GnT, implicating the EGF receptor (EGF-R) in C2GnT suppression, and the EGF-R tyrosine kinase inhibitor AG1478 blocked C2GnT suppression, confirming the role of EGF-R in the inhibition of C2GnT expression. Also, PD98059, a specific inhibitor of mitogen-activated protein kinase/extracellular signal-regulated kinase kinase (MEK)1/2 in the Ras-mitogen-activated protein kinase pathway, completely blocked the EGF suppressive effect, suggesting possible involvement of the Ras-mitogen-activated protein kinase pathway in EGF-mediated downregulation of C2GnT. The results of this study suggest that exposure of airway cells to EGF may result in remodeling of mucin carbohydrate structure, potentially altering the biological properties of the cells.