Tissue transglutaminase serves as an inhibitor of aoptosis by cross-linking caspase 3 in thapsigargin-treated cells
Tissue transglutaminase serves as an inhibitor of aoptosis by cross-linking caspase 3 in thapsigargin-treated cells
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DOI：
10.1128/mcb.26.2.569-579.2006
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发表时间：
2006-01-01
影响因子：
5.3
通讯作者：
Wang, HG
中科院分区：
文献类型：
--
作者：
Yamaguchi, H;Wang, HG
Thapsigargin (THG) 是一种内质网 Ca2+-ATPase 抑制剂，可通过 Bax 依赖性途径诱导 HCT116 细胞中 caspase 3 激活和凋亡。然而，在 Bax 缺陷的 HCT116 细胞中，THG 通过未知机制特异性生成另外两种 caspase 3，称为 p40 和 p64，分子量分别约为 40 和 64 kDa。在此，我们报道Ca2+依赖性蛋白交联酶组织转谷氨酰胺酶（tTGase）通过催化caspase 3交联反应参与THG诱导的p40和p64形成，从而使Caspase 3失活并导致Bax缺陷细胞凋亡。 tTGase 的过表达会增加 THG 处理的细胞中的 p40 和 p64，并且纯化的 tTGase 在体外催化 procaspase 3 交联。通过 tTGase 抑制剂 monodansyleadaverine 或短发夹 RNA 抑制 tTGase 活性，可减少交联物质 p40 和 p64，并恢复 THG 处理后的 caspase 3 活化。此外，长时间暴露于 THG 会导致 XIAP 和 cIAP-1 蛋白水平降低，随后 tTGase 蛋白表达和活性增加。胞质 Smac 的表达使 Bax 缺陷细胞对 THG 诱导的细胞凋亡敏感；然而，这种效应会因 tTGase 的共表达而减弱。综上所述，这些结果表明 tTGase 作为新型 caspase 3 抑制剂在 THG 介导的细胞凋亡中具有新的作用。
Thapsigargin (THG) is an inhibitor of the endoplasmic reticulum Ca2+-ATPase that induces caspase 3 activation and apoptosis in HCT116 cells through a Bax-dependent pathway. In Bax-deficient HCT116 cells, however, THG specifically generates two additional species of caspase 3, termed p40 and p64, with molecular masses of approximately 40 and 64 kDa, respectively, through unknown mechanisms. Here, we report that the Ca2+-dependent protein cross-linking enzyme tissue transglutaminase (tTGase) is involved in THG-induced p40 and p64 formation by catalyzing caspase 3 cross-linking reactions, thereby inactivating caspase 3 and apoptosis in Bax-deficient cells. Overexpression of tTGase increases p40 and p64 in THG-treated cells, and purified tTGase catalyzes procaspase 3 cross-linking in vitro. Inhibition of tTGase activity by either the tTGase inhibitor monodansyleadaverine or short-hairpin RNA reduces the cross-linked species p40 and p64 and restores caspase 3 activation in response to THG treatment. Moreover, prolonged exposure to THG results in a decrease in protein levels of XIAP and cIAP-1, which is subsequently followed by an increase in tTGase protein expression and activity. Expression of cytosolic Smac sensitizes Bax-deficient cells to THG-induced apoptosis; however, this effect is diminished by coexpression of tTGase. Taken together, these results suggest a novel role for tTGase as a new type of caspase 3 inhibitor in THG-mediated apoptosis.