A rapid and transient ROS generation by cadmium triggers apoptosis via caspase-dependent pathway in HepG2 cells and this is inhibited through N-acetylcysteine-mediated catalase upregulation
A rapid and transient ROS generation by cadmium triggers apoptosis via caspase-dependent pathway in HepG2 cells and this is inhibited through N-acetylcysteine-mediated catalase upregulation
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DOI：
10.1016/j.taap.2005.07.018
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发表时间：
2006-05-01
影响因子：
3.8
通讯作者：
Lim, Sung-Chul
中科院分区：
文献类型：
--
作者：
Oh, Seon-Hee;Lim, Sung-Chul
虽然活性氧（ROS）参与了镉（Cd）诱导的肝毒性，但ROS在这一途径中的作用仍不清楚。因此，我们试图确定镉诱导的HepG 2细胞死亡的相关分子机制。DNA片段分析和TUNEL染色证实，镉诱导HepG 2细胞凋亡的时间和剂量依赖性的方式。在早期阶段，快速和短暂的ROS生成通过Fas激活和随后的caspase-8依赖性Bid裂解以及钙蛋白酶介导的线粒体Bax裂解触发细胞凋亡。Bid激活的时间与线粒体跨膜电位（MMP）崩溃以及细胞色素c（Cyt c）释放到胞质溶胶中的时间一致。此外，线粒体通透性转换（MPT）孔抑制剂，如环孢素A（CsA）和bongkrekic酸（BA），并没有阻止镉诱导的ROS的产生，MMP的崩溃和细胞色素c的释放。N-乙酰半胱氨酸（NAC）预处理通过过氧化氢酶上调和随后的Fas下调导致完全抑制镉诱导的细胞凋亡。NAC完全阻断了Cd诱导的细胞内ROS的产生、MMP的降解和Cyt c的释放，表明Cd诱导的线粒体功能障碍可能通过ROS介导的信号通路间接调节，Cd诱导的快速、短暂的ROS产生通过caspase依赖的途径和随后的线粒体途径触发细胞凋亡。NAC通过阻断ROS的产生以及过氧化氢酶的上调来抑制镉诱导的细胞凋亡。(c)2005年爱思唯尔公司All rights reserved.
Although reactive oxygen species (ROS) have been implicated in cadmium (Cd)-induced hepatotoxicity, the role of ROS in this pathway remains unclear. Therefore, we attempted to determine the molecular mechanisms relevant to Cd-induced cell death in HepG2 cells. Cd was found to induce apoptosis in the HepG2 cells in a time- and dose-dependent fashion, as confirmed by DNA fragmentation analysis and TUNEL staining. In the early stages, both rapid and transient ROS generation triggered apoptosis via Fas activation and subsequent caspase-8-dependent Bid cleavage, as well as by calpain-mediated mitochondrial Bax cleavage. The timing of Bid activation was coincided with the timing at which the mitochondrial transinembrane potential (MMP) collapsed as well as the cytochrome c (Cyt c) released into the cytosol. Furthermore, mitochondrial permeability transition (MPT) pore inhibitors, such as cyclosporin A (CsA) and bongkrekic acid (BA), did not block Cd-induced ROS generation, MMP collapse and Cyt c release. N-acetylcysteine (NAC) pretreatment resulted in the complete inhibition of the Cd-induced apoptosis via catalase upregulation and subsequent Fas downregulation. NAC treatment also completely blocked the Cd-induced intracellular ROS generation, MMP collapse and Cyt c release, indicating that Cd-induced rnitochondrial dysfunction may be regulated indirectly by ROS-mediated signaling pathway.Taken together, a rapid and transient ROS generation by Cd triggers apoptosis via caspase-dependent pathway and subsequent mitochondrial pathway. NAC inhibits Cd-induced apoptosis through the blocking of ROS generation as well as the catalase upregulation. (c) 2005 Elsevier Inc. All rights reserved.