Hyperosmolarity-Mediated Mitochondrial Dysfunction Requires Transglutaminase-2 in Human Corneal Epithelial Cells
Hyperosmolarity-Mediated Mitochondrial Dysfunction Requires Transglutaminase-2 in Human Corneal Epithelial Cells
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DOI：
10.1002/jcp.22389
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发表时间：
2011-03-01
影响因子：
5.6
通讯作者：
Tong, Louis
中科院分区：
文献类型：
--
作者：
Png, Evelyn;Samivelu, G. K.;Tong, Louis
高渗诱导的眼表细胞死亡是炎症性眼病中线粒体介导的关键事件。转谷氨酰胺酶(TGM)-2是一种交联酶，据称可介导细胞死亡，但其与线粒体的关系尚不清楚。在角膜中，上皮细胞的完整性对于维持角膜的透明度和功能性视力至关重要。我们评估了TGM-2在高渗透压刺激的人角膜上皮细胞（HCE-T）线粒体细胞死亡中的作用及其参与。构建了稳定表达靶向TGM-2 shRNA （shTG）或重组shRNA （shRNA）的HCE-T细胞系。高渗透压条件降低了shRNA细胞的活力并增加了线粒体去极化。然而，在shTG细胞中，高渗透压未能同样程度地诱导线粒体去极化。TGM-2的瞬时过表达导致shTG和shRNA细胞中TGM-2的表达水平非常高。在过表达TGM-2后的shTG细胞中，高渗透压诱导的线粒体去极化程度与类似处理的shRNA细胞相同。TGM-2过表达也会提高转氨酶活性，降低生存能力。它还诱导线粒体去极化，增加caspase-3/7和-9的活性，这些增加被泛caspase抑制剂Z-VAD-FMK部分抑制。高渗刺激后通过线粒体功能障碍引起的角膜上皮细胞凋亡部分依赖于TGM-2。这种依赖于tgm -2的机制部分通过caspase-3/7和-9发生。针对TGM-2的眼表线粒体应激保护可能对高渗应激下细胞的存活具有重要意义。j .细胞。中国生物医学工程学报，2011,25(6):693-699。(C) 2010 Wiley-Liss, Inc。
Hyperosmolar-induced ocular surface cell death is a key mitochondria-mediated event in inflammatory eye diseases. Transglutaminase (TGM)-2, a cross-linking enzyme, is purported to mediate cell death, but its link to mitochondria is unclear. In the cornea, the integrity of the epithelial cells is important for maintaining transparency of the cornea and therefore functional vision. We evaluated the role of TGM-2 and its involvement in hyperosmolarity-stimulated mitochondrial cell death in human corneal epithelial (HCE-T) cells. HCE-T cell lines stably expressing either shRNA targeting TGM-2 (shTG) or scrambled shRNA (shRNA) were constructed. Hyperosmolar conditions reduced viability and increased mitochondrial depolarization in shRNA cells. However, hyperosmolarity failed to induce mitochondrial depolarization to the same extent in shTG cells. Transient overexpression of TGM-2 resulted in very high levels of TGM-2 expression in shTG and shRNA cells. In the case of shTG cells after overexpression of TGM-2, hyperosmolarity induced the same extent of mitochondrial depolarization as similarly treated shRNA cells. Overexpression of TGM-2 also elevated transamidase activity and reduced viability. It also induced mitochondrial depolarization, increased caspase-3/7 and -9 activity, and these increases were partially suppressed by pan-caspase inhibitor Z-VAD-FMK. Corneal epithelial apoptosis via mitochondrial dysfunction after hyperosmolar stimulation is partially dependent on TGM-2. This TGM-2-dependent mechanism occurs in part via caspase-3/7 and -9. Protection against mitochondrial stress in the ocular surface targeting TGM-2 may have important implications in the survival of cells in hyperosmolar stress. J. Cell. Physiol. 226: 693-699, 2011. (C) 2010 Wiley-Liss, Inc.