Reactive Carbonyl Species Activate Caspase-3-Like Protease to Initiate Programmed Cell Death in Plants
Reactive Carbonyl Species Activate Caspase-3-Like Protease to Initiate Programmed Cell Death in Plants
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DOI：
10.1093/pcp/pcw053
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发表时间：
2016-07-01
影响因子：
4.9
通讯作者：
Mano, Jun'ichi
中科院分区：
文献类型：
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作者：
Biswas, Md. Sanaullah;Mano, Jun'ichi
活性氧（ROS）触发的程序性细胞死亡（PCD）是植物对生物和非生物应激源的典型反应。我们最近发现，脂质过氧化物衍生的反应性羰基物质 (RCS)（ROS 的下游产物）可介导氧化信号以引发 PCD。在这里，我们研究了 RCS 启动 PCD 的机制。 Tobacco Bright Yellow-2 培养细胞用丙烯醛（最有效的 RCS 之一）处理。 0.2 mM 的丙烯醛在 5 小时内引起 PCD（即致死），但 0.1 mM 的丙烯醛则不会（亚致死）。具体来说，这两种剂量对细胞造成了截然不同的影响。致死剂量和亚致死剂量的丙烯醛都会在 30 分钟内耗尽细胞谷胱甘肽池，而致死剂量仅在 1-2 小时内导致抗坏血酸显着减少和 ROS 增加。在这种氧化还原变化之前，我们发现丙烯醛会导致 caspase-1 样蛋白酶 (C1LP) 和 caspase-3 样蛋白酶 (C3LP) 的活性显着增加，这两种蛋白酶会引发 PCD。致死剂量的丙烯醛使C3LP活性比亚致死剂量增加2倍。相比之下，两种剂量引起的 C1LP 活性增量没有不同。丙烯醛和另一种 RCS 4-羟基-(E)-2-壬烯醛可激活未经处理细胞的无细胞提取物中的两种蛋白酶。添加到细胞中的 1mM H2O2 增加了 C1LP 和 C3LP 活性并引起 PCD，而 RCS 清除剂肌肽抑制了它们的激活和 PCD。然而，H2O2 不会激活无细胞提取物中的蛋白酶。因此，RCS 激活 caspase 样蛋白酶，特别是 C3LP，是植物中氧化信号刺激的 PCD 的初始生化事件。
Reactive oxygen species (ROS)-triggered programmed cell death (PCD) is a typical plant response to biotic and abiotic stressors. We have recently shown that lipid peroxide-derived reactive carbonyl species (RCS), downstream products of ROS, mediate oxidative signal to initiate PCD. Here we investigated the mechanism by which RCS initiate PCD. Tobacco Bright Yellow-2 cultured cells were treated with acrolein, one of the most potent RCS. Acrolein at 0.2 mM caused PCD in 5 h (i.e. lethal), but at 0.1 mM it did not (sublethal). Specifically, these two doses caused critically different effects on the cells. Both lethal and sublethal doses of acrolein exhausted the cellular glutathione pool in 30 min, while the lethal dose only caused a significant ascorbate decrease and ROS increase in 1-2 h. Prior to such redox changes, we found that acrolein caused significant increases in the activities of caspase-1-like protease (C1LP) and caspase-3-like protease (C3LP), the proteases which trigger PCD. The lethal dose of acrolein increased the C3LP activity 2-fold more than did the sublethal dose. In contrast, C1LP activity increments caused by the two doses were not different. Acrolein and 4-hydroxy-(E)-2-nonenal, another RCS, activated both proteases in a cell-free extract from untreated cells. H2O2 at 1mM added to the cells increased C1LP and C3LP activities and caused PCD, and the RCS scavenger carnosine suppressed their activation and PCD. However, H2O2 did not activate the proteases in a cell-free extract. Thus the activation of caspase-like proteases, particularly C3LP, by RCS is an initial biochemical event in oxidative signal-stimulated PCD in plants.