The Long-Lived Nature of Clostridium perfringens Iota Toxin in Mammalian Cells Induces Delayed Apoptosis
The Long-Lived Nature of Clostridium perfringens Iota Toxin in Mammalian Cells Induces Delayed Apoptosis
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DOI：
10.1128/iai.00710-09
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发表时间：
2009-12-01
影响因子：
3.1
通讯作者：
Barth, Holger
中科院分区：
文献类型：
--
作者：
Hilger, Hanna;Pust, Sascha;Barth, Holger
细菌毒素，如产气荚膜梭菌毒素或肉毒梭菌C2毒素，使肌动蛋白发生单-ADP核糖基化，导致肌动蛋白细丝快速解聚和细胞变圆。在这里，我们报告了用IOTA毒素处理非洲绿猴肾(Vero)细胞导致caspase依赖的延迟死亡。未经修饰的肌动蛋白在毒素处理的细胞中不再出现，酶活性毒素在胞浆中至少可检测到24小时。C2毒素在细胞中显示出类似的长期效应，而缺乏ADP核糖转移酶活性的C2毒素对照不会诱导细胞死亡。为了解决IOTA和C2毒素在胞浆中的显著稳定性是否对诱导细胞死亡至关重要，我们用肠沙门氏菌SpvB的催化结构域C/SpvB处理细胞。虽然与IOTA和C2毒素一样，C/SpvB也能使肌动蛋白单链ADP核糖化，但用渗透细胞的C/SpvB融合毒素处理的细胞变圆，但恢复并保持活力。此外，未修饰的肌动蛋白在这些细胞中再次出现，24小时后胞浆中检测不到C/SpvB所致的ADP-核糖转移酶活性，这很可能是由于C/SpvB的降解所致。反复应用C/SpvB阻止了细胞的恢复和未修饰肌动蛋白的重新出现。总之，完整但短暂的肌动蛋白ADP核糖化不足以触发细胞凋亡，这意味着胞浆中肌动蛋白-ADP-核糖化毒素(如IOTA和C2)的长期稳定性对于诱导caspase依赖的延迟性细胞死亡至关重要。
Mono-ADP ribosylation of actin by bacterial toxins, such as Clostridium perfringens iota or Clostridium botulinum C2 toxins, results in rapid depolymerization of actin filaments and cell rounding. Here we report that treatment of African green monkey kidney (Vero) cells with iota toxin resulted in delayed caspase-dependent death. Unmodified actin did not reappear in toxin-treated cells, and enzyme-active toxin was detectable in the cytosol for at least 24 h. C2 toxin showed comparable, long-lived effects in cells, while a C2 toxin control lacking ADP-ribosyltransferase activity did not induce cell death. To address whether the remarkable stability of the iota and C2 toxins in cytosol was crucial for inducing cell death, we treated cells with C/SpvB, the catalytic domain of Salmonella enterica SpvB. Although C/SpvB also mono-ADP ribosylates actin as do the iota and C2 toxins, cells treated with a cell-permeating C/SpvB fusion toxin became rounded but recovered and remained viable. Moreover, unmodified actin reappeared in these cells, and ADP-ribosyltransferase activity due to C/SpvB was not detectable in the cytosol after 24 h, a result most likely due to degradation of C/SpvB. Repeated application of C/SpvB prevented recovery of cells and reappearance of unmodified actin. In conclusion, a complete but transient ADP ribosylation of actin was not sufficient to trigger apoptosis, implying that long-term stability of actin-ADP-ribosylating toxins, such as iota and C2, in the cytosol is crucial for inducing delayed, caspase-dependent cell death.