The N-terminal 34 kDa fragment of Helicobacter pylori vacuolating cytotoxin targets mitochondria and induces cytochrome c release
The N-terminal 34 kDa fragment of Helicobacter pylori vacuolating cytotoxin targets mitochondria and induces cytochrome c release
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DOI：
10.1093/emboj/19.23.6361
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发表时间：
2000-12-01
期刊：
影响因子：
11.4
通讯作者：
Boquet, P
中科院分区：
文献类型：
--
作者：
Galmiche, A;Rassow, J;Boquet, P
致病细菌幽门螺杆菌产生细胞毒素VacA，它与胃上皮病变的发生有关。通过用编码VacA的N端(P34)或C端(P58)片段的DNA转染Hep-2细胞，发现p34特异性地定位于线粒体，而p58是胞质的。在体外与纯化的线粒体孵育，VacA和p34而不是p58移位到线粒体中，显微注射编码VacA-GFP和p34-GFP的DNA，而不是GFP-VacA或GFP-p34，通过诱导细胞凋亡来诱导细胞死亡。用p34-GFP或VacA-GFP瞬时转染HeLa细胞，通过裂解多聚ADP-核糖聚合酶(PARP)，诱导细胞色素c从线粒体释放，并激活执行因子caspase3。PARP的裂解可以通过共转染编码Bcl2的DNA而被特异性地拮抗，已知Bcl2可以阻断线粒体依赖的凋亡信号。这些观察结果与VacA作用的体内机制的相关性得到了以下事实的支持：纯化的活性VacA外加到细胞外，诱导细胞色素c释放到胞浆中。
The pathogenic bacterium Helicobacter pylori produces the cytotoxin VacA, which is implicated in the genesis of gastric epithelial lesions. By transfecting HEp-2 cells with DNAs encoding either the N-terminal (p34) or the C-terminal (p58) fragment of VacA, p34 was found localized specifically to mitochondria, whereas p58 was cytosolic. Incubated in vitro with purified mitochondria, VacA and p34 but not p58 translocated into the mitochondria, Microinjection of DNAs encoding VacA-GFP and p34-GFP, but not GFP-VacA or GFP-p34, induced cell death by apoptosis. Transient transfection of HeLa cells with p34-GFP or VacA-GFP induced the release of cytochrome c from mitochondria and activated the executioner caspase 3, as determined by the cleavage of poly(ADP-ribose) polymerase (PARP). PARP cleavage was antagonized specifically by co-transfection of DNA encoding Bcl-2, known to block mitochondria-dependent apoptotic signals. The relevance of these observations to the in viva mechanism of VacA action was supported by the fact that purified activated VacA applied externally to cells induced cytochrome c release into the cytosol.