Rapid cytochrome c release, activation of caspases 3, 6, 7 and 8 followed by Bap31 cleavage in HeLa cells treated with photodynamic therapy
Rapid cytochrome c release, activation of caspases 3, 6, 7 and 8 followed by Bap31 cleavage in HeLa cells treated with photodynamic therapy
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DOI：
10.1016/s0014-5793(98)01193-4
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发表时间：
1998-10-16
期刊：
影响因子：
3.5
通讯作者：
Hunt, DWC
中科院分区：
文献类型：
--
作者：
Granville, DJ;Carthy, CM;Hunt, DWC
光动力疗法(PDT)是一种利用光激活药物治疗各种病理情况的临床方法。PDT诱导的细胞凋亡的启动事件还不清楚。对于其他促凋亡刺激，研究表明，整合内质网蛋白Bap31被caspase 1和8切割，但不被caspase-3切割，并产生一个20 kDa的Bap31切割片段，可诱导细胞凋亡。在本报告中，我们试图确定Bap31切割和p20的产生是否是PDT诱导的细胞凋亡的早期事件，细胞色素c的线粒体释放，caspase 1，2，3，4，6，7，8和10的参与，以及包括Bap31在内的几种已知caspase底物的状态。光敏剂苯系单酸环A光激活后，细胞色素c立即出现在胞浆中，caspase3、6、7、8在PDT后1~2 h有明显的激活，caspase 1、2、4、10未见加工，Bap31在PDT后2~3 h有裂解。Caspase-3抑制剂DEVD-fmk阻断了caspase-8和Bap31的切割，提示在PDT诱导的细胞凋亡中，caspase-8和Bap31的处理发生在caspase-3激活的下游。这些结果表明，线粒体细胞色素c的释放是PDT后的主要事件，在caspase激活和切割Bap31之前，据我们所知，这是第一个化疗药物诱导caspase-8激活的例子，并证明caspase-8的激活可以发生在细胞色素c释放之后，(C)1998欧洲生化学会联合会。
Photodynamic therapy (PDT) is a clinical approach that utilizes light-activated drugs for the treatment of a variety of pathologic conditions. The initiating events of PDT-induced apoptosis are poorly defined. It has been shown for other pro-apoptotic stimuli that the integral endoplasmic reticulum protein Bap31 is cleaved by caspases 1 and 8, but not by caspase-3, Further, a 20 kDa Bap31 cleavage fragment is generated which can induce apoptosis, In the current report, we sought to determine whether Bap31 cleavage and generation of p20 is an early event in PDT-induced apoptosis, The mitochondrial release of cytochrome c, involvement of caspases 1, 2, 3, 4, 6, 7, 8, and 10 and the status of several known caspase substrates, including Bap31, were evaluated in PDT-treated HeLa cells. Cytochrome c appeared in the cytosol immediately following light activation of the photosensitizer benzoporphyrin derivative monoacid ring A. Activation of caspases 3, 6, 7, and 8 was evident within 1-2 h post PDT, Processing of caspases 1, 2, 4, and 10 was not observed, Cleavage of Bap31 was observed at 2-3 h post PDT. The caspase-3 inhibitor DEVD-fmk blocked caspase-8 and Bap31 cleavage suggesting that caspase-8 and Bap31 processing occur downstream of caspase-3 activation in PDT-induced apoptosis, These results demonstrate that release of mitochondrial cytochrome c into the cytoplasm is a primary event following PDT, preceding caspase activation and cleavage of Bap31, To our knowledge, this is the first example of a chemotherapeutic agent inducing caspase-8 activation and demonstrates that caspase-8 activation can occur after cytochrome c release, (C) 1998 Federation of European Biochemical Societies.