Ricin A-chain requires c-Jun N-terminal kinase to induce apoptosis in nontransformed epithelial cells
Ricin A-chain requires c-Jun N-terminal kinase to induce apoptosis in nontransformed epithelial cells
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DOI：
10.1016/j.biocel.2009.08.007
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发表时间：
2009-12-01
影响因子：
4
通讯作者：
Cohick, Wendie S.
中科院分区：
文献类型：
--
作者：
Jetzt, Amanda E.;Cheng, Ju-Shun;Cohick, Wendie S.
蓖麻毒素是从蓖麻子中分离出来的一种毒素，有可能成为生物恐怖主义的武器。这种糖蛋白由破坏核糖体并抑制蛋白质合成的 A 链 (RTA) 和在细胞摄取中发挥作用的 B 链组成。蓖麻毒素激活 c-Jun N 末端激酶 (JNK) 和 p38 信号通路；然而，这些途径在蓖麻毒素诱导的细胞死亡中的作用尚未得到研究。我们的目标是确定仅 RTA 是否可以激活细胞凋亡，以及该反应是否需要 JNK 和 p38 途径。在永生化、非转化上皮细胞系 MAC-T 中，用蓖麻毒素和 RTA 处理观察到类似的 caspase 激活。用1μg/ml RTA在2-4小时内诱导核糖体脱嘌呤和蛋白质合成的抑制，用0.1μg/ml RTA在4-6小时内诱导。直到用任一 RTA 浓度处理 4 小时后才观察到细胞凋亡。 RTA 以时间和浓度依赖性方式激活 JNK 和 p38，随后细胞凋亡增加。 JNK 通路的抑制减少了 RTA 诱导的 caspase 激活和聚 (ADP-核糖) 聚合酶裂解。相反，p38 通路的抑制对 RTA 诱导的 caspase 3/7 激活几乎没有影响。这些研究首次证明了 JNK 信号通路在蓖麻毒素诱导的细胞死亡中的作用。此外，MAC-T 细胞系被证明是一种敏感的体外模型系统，可供未来研究使用 RTA 突变体来确定 RTA 诱导的脱嘌呤、核糖应激和正常上皮细胞凋亡之间的关系。 (C) 2009 Elsevier Ltd. 保留所有权利。
Ricin is a toxin isolated from castor beans that has potential as a weapon of bioterrorism. This glycoprotein consists of an A-chain (RTA) that damages the ribosome and inhibits protein synthesis and a B-chain that plays a role in cellular uptake. Ricin activates the c-Jun N-terminal kinase (JNK) and p38 signaling pathways; however, a role for these pathways in ricin-induced cell death has not been investigated. Our goals were to determine if RTA alone could activate apoptosis and if the JNK and p38 pathways were required for this response. Comparable caspase activation was observed with both ricin and RTA treatment in the immortalized, nontransformed epithelial cell line, MAC-T. Ribosome depurination and inhibition of protein synthesis were induced in 2-4 h with 1 mu g/ml RTA and within 4-6 h with 0.1 mu g/ml RTA. Apoptosis was not observed until 4h of treatment with either RTA concentration. RTA activated JNK and p38 in a time- and concentration-dependent manner that preceded increases in apoptosis. Inhibition of the JNK pathway reduced RTA-induced caspase activation and poly(ADP-ribose) polymerase cleavage. In contrast, inhibition of the p38 pathway had little effect on RTA-induced caspase 3/7 activation. These studies are the first to demonstrate a role for the JNK signaling pathway in ricin-induced cell death. In addition, the MAC-T cell line is shown to be a sensitive in vitro model system for future studies using RTA mutants to determine relationships between RTA-induced depurination, ribotoxic stress, and apoptosis in normal epithelial cells. (C) 2009 Elsevier Ltd. All rights reserved.