ADP-ribosylation of actin by the Clostridium botulinum C2 toxin in mammalian cells results in delayed caspase-dependent apoptotic cell death
ADP-ribosylation of actin by the Clostridium botulinum C2 toxin in mammalian cells results in delayed caspase-dependent apoptotic cell death
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DOI：
10.1128/iai.00651-08
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发表时间：
2008-10-01
影响因子：
3.1
通讯作者：
Barth, Holger
中科院分区：
文献类型：
--
作者：
Heine, Karin;Pust, Sascha;Barth, Holger
肉毒梭菌单adp核糖体中的二C2毒素在真核细胞的胞浆中使g -肌动蛋白发生核糖基化。这种修饰会导致肌动蛋白丝的解聚，并在3小时内引起细胞变圆，但不会立即引起细胞死亡。在这里，我们研究了哺乳动物细胞系（HeLa和Vero）在C2毒素处理后的长期反应。即使毒素内化到细胞后被从培养基中移除，细胞仍然保持原状。在C2毒素处理的细胞中，48小时内没有出现未修饰的肌动蛋白。尽管肌动蛋白在约7小时后完全被adp核糖化，但至少48小时内没有观察到肌动蛋白总量的明显减少。因此，adp核糖化不是肌动蛋白加速降解的信号。C2毒素处理导致延迟的凋亡细胞死亡，在毒素应用于部分细胞后约15至24小时可检测到。Poly(ADP)-核糖基转移酶1 （PARP-1）在C2毒素处理的细胞中被切割，这是caspase 3激活的指示和细胞凋亡的标志。此外，特异性的caspase抑制剂阻止了C2毒素诱导的细胞凋亡，这表明caspase 8和9在C2毒素处理的细胞中被激活。C2毒素的adp -核糖基转移酶组分C2I在细胞质中保持活性至少48小时，未观察到C2I的广泛降解。根据我们的数据，我们得出结论，宿主细胞质中C2I的长寿命性质是C2毒素不可逆转的细胞毒性作用所必需的，导致被测试的哺乳动物细胞延迟凋亡。
The binary C2 toxin from Clostridium botulinum mono-ADP-ribosylates G-actin in the cytosol of eukaryotic cells. This modification leads to depolymerization of actin filaments accompanied by cell rounding within 3 h of incubation but does not immediately induce cell death. Here we investigated the long-term responses of mammalian cell lines (HeLa and Vero) following C2 toxin treatment. Cells stayed round even though the toxin was removed from the medium after its internalization into the cells. No unmodified actin reappeared in the C2 toxin-treated cells within 48 h. Despite actin being completely ADP-ribosylated after about 7 h, no obvious decrease in the overall amount of actin was observed for at least 48 h. Therefore, ADP-ribosylation was not a signal for an accelerated degradation of actin in the tested cell lines. C2 toxin treatment resulted in delayed apoptotic cell death that became detectable about 15 to 24 h after toxin application in a portion of the cells. Poly(ADP)-ribosyltransferase 1 (PARP-1) was cleaved in C2 toxin-treated cells, an indication of caspase 3 activation and a hallmark of apoptosis. Furthermore, specific caspase inhibitors prevented C2 toxin-induced apoptosis, implying that caspases 8 and 9 were activated in C2 toxin-treated cells. C2I, the ADP-ribosyltransferase component of the C2 toxin, remained active in the cytosol for at least 48 h, and no extensive degradation of C2I was observed. From our data, we conclude that the long-lived nature of C2I in the host cell cytosol was essential for the nonreversible cytotoxic effect of C2 toxin, resulting in delayed apoptosis of the tested mammalian cells.