Paraoxon induces apoptosis in EL4 cells via activation of mitochondrial pathways
Paraoxon induces apoptosis in EL4 cells via activation of mitochondrial pathways
复制标题
DOI：
10.1016/s0041-008x(03)00126-1
复制
发表时间：
2003-07-01
影响因子：
3.8
通讯作者：
Kambal, A
中科院分区：
文献类型：
--
作者：
Saleh, AM;Vijayasarathy, C;Kambal, A
有机磷化合物的毒性，如对氧磷（POX），是由于它们的抗胆碱酯酶作用。最近，我们已经证明，在非合并剂量（1至10 nM）下，POX（对硫磷的生物活性代谢物）通过激活caspase-3导致小鼠EL4 t淋巴细胞白血病细胞系的凋亡细胞死亡。在这项研究中，通过使用caspase特异性抑制剂，我们扩展了我们的观察，以阐明pox刺激的细胞凋亡所涉及的事件序列。用caspase-9特异性抑制剂zLEHD-fmk预处理EL4细胞，以剂量依赖的方式减弱pox诱导的凋亡，而caspase-8抑制剂zIETD-fmk则没有作用。此外，在zLEHD-ftnk的存在下，caspase-9、-8和-3在痘处理下的激活完全被抑制，这表明caspase-9依赖的线粒体通路参与了痘刺激的细胞凋亡。事实上，在体外和体内条件下，正如Western blot分析所评估的那样，POX触发了细胞色素c从线粒体到细胞质的剂量和时间依赖性易位。细胞色素c释放机制的研究表明，天花破坏了线粒体跨膜电位。这种作用和细胞色素c的释放都不依赖于caspase的激活，因为caspase家族的一般抑制剂zVAD-ftnk不影响这两个过程。最后，痘处理还导致促凋亡分子Bax的时间依赖性上调和易位到线粒体。zad -fmk对这一事件的抑制表明，在caspase级联激活之后，Bax的激活和转运到线粒体。结果表明，POX通过破坏线粒体的跨膜电位，直接影响线粒体，导致细胞色素c释放到细胞质中，随后激活caspase-9，从而诱导EL4细胞凋亡。抑制这一特定途径可能为减少有机磷中毒提供了一种有用的策略。(C) 2003 Elsevier Science（美国）版权所有。
The toxicity of organophosphorus compounds, such as paraoxon (POX), is due to their anticholinesterase action. Recently, we have shown that, at nonchotmergic doses (1 to 10 nM), POX (the bioactive metabolite of parathion) causes apoptotic cell death in murine EL4 T-lymphocytic leukemia cell line through activation of caspase-3. In this study, by employing caspase-specific inhibitors, we extend our observations to elucidate the sequence of events involved in POX-stimulated apoptosis. Pretreatment of EL4 cells with the caspase-9-specific inhibitor zLEHD-fmk attenuated POX-induced apoptosis in a dose-dependent manner, whereas the caspase-8 inhibitor zIETD-fmk had no effect. Furthermore, the activation of caspase-9, -8, and -3 in response to POX treatment was completely inhibited in the presence of zLEHD-ftnk, implicating the involvement of caspase 9-dependent mitochondrial pathways in POX-stimulated apoptosis. Indeed, under both in vitro and in vivo conditions, POX triggered a dose- and time-dependent translocation of cytochrome c from mitochondria into the cytosol, as assessed by Western blot analysis. Investigation of the mechanism of cytochrome c release revealed that POX disrupted mitochondrial transmembrane potential. Neither this effect nor cytchrome c release was dependent on caspase activation, since the general inhibitor of the caspase family zVAD-ftnk did not influence both processes. Finally, POX treatment also resulted in a time-dependent up-regulation and translocation of the proapoptotic molecule Bax to mitochondria. Inhibition of this event by zVAD-fmk suggests that the activation and translocation of Bax to mitochondria is subsequent to activation of the caspase cascades. The results indicate that POX induces apoptosis in EL4 cells through a direct effect on mitochondria by disrupting its transmembrane potential, causing the release of cytochrome c into the cytosol and subsequent activation of caspase-9. Inhibition of this specific pathway might provide a useful strategy to minimize organophosphate-induced poisoning. (C) 2003 Elsevier Science (USA). All rights reserved.