Trefoil factor TFF1-induced protection of conjunctival cells from apoptosis at premitochondrial and postmitochondrial levels
Trefoil factor TFF1-induced protection of conjunctival cells from apoptosis at premitochondrial and postmitochondrial levels
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DOI：
10.1167/iovs.07-1270
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发表时间：
2008-09-01
影响因子：
4.4
通讯作者：
Solary, Eric
中科院分区：
文献类型：
--
作者：
Buron, Nelly;Guery, Leslie;Solary, Eric
目的。结膜上皮的杯状细胞合成和分泌TFF1(三叶因子1)，这是一种抗蛋白酶的小肽，与粘蛋白一起负责泪膜的流变性。本研究的目的是确定在翼状胬肉等炎症条件下合成增加的TFF1是否可以保护结膜细胞免受凋亡的影响。方法：将野生型或稳定表达TFF1的Chang结膜细胞暴露于苯扎氯铵(BAK)和紫外线(UV)照射，以触发细胞凋亡。采用细胞分级法检测脂筏相关蛋白，免疫共沉淀法检测死亡诱导信号复合体(DISC)的形成，结合免疫荧光、免疫印迹、流式细胞仪、siRNA介导的基因表达下调和凝胶迁移率改变实验，探讨TFF1保护结膜细胞的机制。首先，TFF1可在视盘水平阻止caspase-8的激活，这涉及到质膜筏上的Fas受体，进而减少线粒体细胞色素c的释放。其次，TFF1通过核因子-kappa B诱导的XIAP(X连锁的凋亡抑制蛋白)表达的增加来干扰caspase-9和caspase-3的激活。结论：TFF1上调炎症条件可能是通过抑制线粒体事件上下游的凋亡来限制结膜细胞损失的一种保护机制。这些观察表明，TFF1或相关多肽在预防眼表疾病中的细胞死亡方面具有潜在的兴趣。
PURPOSE. Goblet cells of the conjunctival epithelium synthesize and secrete TFF1 (Trefoil factor 1), a small protease-resistant peptide that, together with mucins, is responsible for the rheologic properties of the tear film. This study aimed to determine whether TFF1, whose synthesis increases in inflammatory conditions such as pterygium, could protect conjunctival cells from apoptosis.METHODS. Chang conjunctival cells, either wild-type or expressing TFF1 through stable transfection, were exposed to benzalkonium chloride (BAK) and ultraviolet (UV) irradiation to trigger apoptosis. The authors used cell fractionation to detect lipid raft-associated proteins, coimmunoprecipitation to explore the formation of a death-inducing signaling complex (DISC), and a combination of immunofluorescence, immuno-blotting, flow cytometry, siRNA-mediated decrease in gene expression, and electrophoretic mobility shift assay to explore the mechanisms of TFF1-protective effects.RESULTS. TFF1 protects Chang conjunctival cells from apoptosis induced by UV irradiation and BAK at two levels. First, TFF1 prevents caspase-8 activation at the level of the DISC that involves Fas receptor in plasma membrane rafts, which in turn decreases the mitochondrial release of cytochrome c. Second, TFF1 interferes with caspase-9 and caspase-3 activation through an NF-kappa B-induced increase in the expression of XIAP (X-linked inhibitor of apoptosis protein).CONCLUSIONS. TFF1 upregulation on inflammatory conditions may be a protective mechanism that limits conjunctival cell loss by inhibiting apoptosis upstream and downstream of the mitochondrial events. These observations suggest a potential interest of TFF1 or related peptides to prevent cell death in ocular surface disorders.