Association of Cell Surface Mucins with Galectin-3 Contributes to the Ocular Surface Epithelial Barrier
Association of Cell Surface Mucins with Galectin-3 Contributes to the Ocular Surface Epithelial Barrier
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DOI：
10.1074/jbc.m109.033332
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发表时间：
2009-08-21
影响因子：
4.8
通讯作者：
Panjwani, Noorjahan
中科院分区：
文献类型：
--
作者：
Argueso, Pablo;Guzman-Aranguez, Ana;Panjwani, Noorjahan
维持完整的粘膜屏障对于防止湿表面上皮细胞的损伤和感染至关重要。防御机制一直是许多研究的主题，现在有证据表明上皮细胞表面的O-糖基化粘蛋白。在这里，我们研究了一个新的角色，碳水化合物结合蛋白半乳糖凝集素3在稳定粘膜屏障，通过其相互作用与粘蛋白的顶端糖萼。使用眼睛的表面作为模型系统，我们发现，半乳糖凝集素-3共定位与两个不同的膜相关的粘蛋白，MUC 1和MUC 16，上皮细胞的顶端表面上，这两个粘蛋白结合半乳糖凝集素-3亲和柱在半乳糖依赖性的方式。使用半乳糖凝集素结合的竞争性碳水化合物抑制剂、β-乳糖和改性柑橘果胶消除四种不同粘膜上皮细胞类型中的粘蛋白-半乳糖凝集素相互作用，导致细胞表面上半乳糖凝集素-3水平降低，伴随屏障功能丧失，如对玫瑰红诊断染料的渗透性增加所示。同样，下调粘蛋白O-糖基化，使用稳定的四环素诱导的RNA干扰系统敲低c1 galt 1（T-合成酶），一个关键的半乳糖基转移酶所需的核心1 O-聚糖，导致细胞表面O-糖基化减少，细胞表面半乳糖凝集素-3减少，上皮通透性增加。总之，这些结果表明，半乳糖凝集素-3通过与细胞表面粘蛋白的碳水化合物依赖性相互作用在维持粘膜屏障功能中起关键作用。
Maintenance of an intact mucosal barrier is critical to preventing damage to and infection of wet-surfaced epithelia. The mechanism of defense has been the subject of much investigation, and there is evidence now implicating O-glycosylated mucins on the epithelial cell surface. Here we investigate a new role for the carbohydrate-binding protein galectin-3 in stabilizing mucosal barriers through its interaction with mucins on the apical glycocalyx. Using the surface of the eye as a model system, we found that galectin-3 colocalized with two distinct membrane-associated mucins, MUC1 and MUC16, on the apical surface of epithelial cells and that both mucins bound to galectin-3 affinity columns in a galactose-dependent manner. Abrogation of the mucin-galectin interaction in four different mucosal epithelial cell types using competitive carbohydrate inhibitors of galectin binding, beta-lactose and modified citrus pectin, resulted in decreased levels of galectin-3 on the cell surface with concomitant loss of barrier function, as indicated by increased permeability to rose bengal diagnostic dye. Similarly, down-regulation of mucin O-glycosylation using a stable tetracycline-inducible RNA interfering system to knockdown c1galt1 (T-synthase), a critical galactosyltransferase required for the synthesis of core 1 O-glycans, resulted in decreased cell surface O-glycosylation, reduced cell surface galectin-3, and increased epithelial permeability. Taken together, these results suggest that galectin-3 plays a key role in maintaining mucosal barrier function through carbohydrate-dependent interactions with cell surface mucins.