Involvement of proapoptotic molecules Bax and Bak in tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-induced mitochondrial disruption and apoptosis: differential regulation of cytochrome c and Smac/DIABLO release.
Involvement of proapoptotic molecules Bax and Bak in tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-induced mitochondrial disruption and apoptosis: differential regulation of cytochrome c and Smac/DIABLO release.
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发表时间：
2003-04
期刊：
影响因子：
11.2
通讯作者：
Karthikeyan Kandasamy;S. Srinivasula;E. Alnemri;C. Thompson;S. Korsmeyer;J. Bryant;R. K Srivastava
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作者：
Karthikeyan Kandasamy;S. Srinivasula;E. Alnemri;C. Thompson;S. Korsmeyer;J. Bryant;R. K Srivastava
肿瘤坏死因子相关凋亡诱导配体（TRAIL）/Apo 2L在多种癌症和转化细胞中诱导凋亡。BID是一种“仅含BH 3结构域”的Bcl-2家族成员，其激活可触发促凋亡家族成员巴克或Bax的寡聚化，导致线粒体蛋白释放到胞质溶胶中。在这项研究中，我们通过研究Bax（-/-）和巴克（-/-）动物的小鼠胚胎成纤维细胞（MEFs），显示了Bax和巴克在TRAIL诱导的细胞凋亡中的重要性。在野生型、Bid（-/-）、Bax（-/-）或巴克（-/-）MEFs中，TRAIL诱导细胞色素c释放和凋亡，但在Bax（-/-）巴克（-/-）双敲除（DKO）MEFs中不诱导细胞色素c释放和凋亡。Bid在细胞色素c释放的上游起作用，在除Bid（-/-）MEF之外的所有敲除细胞中被切割。细胞色素c的释放与caspase-9活性相关。TRAIL增加了除DKO细胞外的所有细胞中的caspase-3活性。在DKO MEFs中未观察到TRAIL诱导的线粒体膜电位下降。与细胞色素c释放不同，TRAIL诱导的Smac/DIABLO释放在Bid（-/-）、Bax（-/-）、巴克（-/-）或DKO MEFs中被阻断，表明这些线粒体蛋白在凋亡期间的差异调节。在DKO MEFs中，线粒体下游的凋亡事件是完整的，因为细胞色素c的显微注射，或成熟Smac/DIABLO的异位表达或Smac N7肽的预处理完全恢复了TRAIL的敏感性。总之，数据表明Bax和巴克差异调节细胞色素c和Smac/DIABLO从线粒体的释放，并且Smac/DIABLO可用于致敏Bax和巴克基因缺陷或对TRAIL具有抗性的细胞。
Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)/Apo2L induces apoptosis in a wide variety of cancer and transformed cells. Activation of BID, a "BH3-domain-only" Bcl-2 family member, triggers the oligomerization of proapoptotic family members Bak or Bax, resulting in the release of mitochondrial proteins to cytosol. In this study, we have shown the importance of Bax and Bak in TRAIL-induced apoptosis by studying in murine embryonic fibroblasts (MEFs) from Bax(-/-) and Bak(-/-) animals. TRAIL induced cytochrome c release and apoptosis in wild-type, Bid(-/-), Bax(-/-), or Bak(-/-) MEFs, but not in Bax(-/-) Bak(-/-) double knockout (DKO) MEFs. Bid, which functions upstream of cytochrome c release, was cleaved in all of the knockout cells except in Bid(-/-) MEFs. The release of cytochrome c was correlated with caspase-9 activity. TRAIL increased caspase-3 activity in all of the cells except in DKO cells. TRAIL-induced drop in mitochondrial membrane potential was not observed in DKO MEFs. Unlike cytochrome c release, TRAIL-induced Smac/DIABLO release was blocked in Bid(-/-), Bax(-/-), Bak(-/-), or DKO MEFs, suggesting the differential regulation of these mitochondrial proteins during apoptosis. The apoptotic events downstream of mitochondria were intact in DKO MEFs, because microinjection of cytochrome c, or ectopic expression of mature Smac/DIABLO or pretreatment of Smac N7 peptide completely restored TRAIL sensitivity. In conclusion, the data suggest that Bax and Bak differentially regulate the release of cytochrome c and Smac/DIABLO from mitochondria, and Smac/DIABLO can be used to sensitize cells that are deficient in Bax and Bak genes, or resistant to TRAIL.