Ordering of caspases in cells undergoing apoptosis by the intrinsic pathway
Ordering of caspases in cells undergoing apoptosis by the intrinsic pathway
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DOI：
10.1038/cdd.2009.29
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发表时间：
2009-07-01
影响因子：
12.4
通讯作者：
Cohen, G. M.
中科院分区：
文献类型：
--
作者：
Inoue, S.;Browne, G.;Cohen, G. M.
半胱氨酸蛋白酶是一类天冬氨酸特异性半胱氨酸蛋白酶家族，负责细胞凋亡执行阶段发生的生化和形态变化。使用dATP激活的细胞裂解产物来模拟初始线粒体扰动诱导的内在途径，已经清楚地建立了caspase的层级排序。在这个模型中，顶端的caspase-9直接处理和激活效应caspase，caspase-3和-7，然后激活caspase-3，而不是caspase-7，处理caspase-2和-6，然后激活的caspase-6处理caspase-8和-10。为了解决这个体外模型系统可能不能反映完整细胞中caspase的精确排序的可能性，我们在通过激活内在途径诱导细胞凋亡的情况下研究了这种可能性。我们使用了caspase缺陷细胞，caspase-6和caspase-7的小干扰RNA，以及特异性的caspase-3抑制剂。与早期的体外研究相比，我们现在发现，在完整的细胞中，caspase-7也可以直接处理和激活caspase-2和-6。Caspase-2和-6的处理发生在细胞质内，然后活性的caspase-6负责caspase-8的处理和caspase-6底物的切割，包括层蛋白A/C。
Caspases are a family of aspartate-specific cysteine proteases responsible for the biochemical and morphological changes that occur during the execution phase of apoptosis. The hierarchical ordering of caspases has been clearly established using dATP-activated cell lysates to model the intrinsic pathway induced by initial mitochondrial perturbation. In this model, caspase-9, the apical caspase, directly processes and activates the effector caspases, caspase-3 and -7, and then active caspase-3 but not caspase-7, processes caspase-2 and -6, and subsequently the activated caspase-6 processes caspase-8 and -10. To address the possibility that this model in vitro system might not reflect the precise ordering of caspases in intact cells, we have examined this possibility in cells induced to undergo apoptosis by activation of the intrinsic pathway. We have used caspase deficient cells, small interference RNA for caspase-6 and -7, and a specific caspase-3 inhibitor. In contrast to the earlier in vitro studies, we now show that in intact cells caspase-7 can also directly process and activate caspase-2 and -6. The processing of caspase-2 and -6 occurs within the cytoplasm and active caspase-6 is then responsible for both the processing of caspase-8 and the cleavage of caspase-6 substrates, including lamin A/C.