Apoptosome-independent pathway for apoptosis -: Biochemical analysis of APAF-1 defects and biological outcomes
Apoptosome-independent pathway for apoptosis -: Biochemical analysis of APAF-1 defects and biological outcomes
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DOI：
10.1074/jbc.m302924200
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发表时间：
2003-08-08
影响因子：
4.8
通讯作者：
Ségal-Bendirdjian, E
中科院分区：
文献类型：
--
作者：
Belmokhtar, CA;Hillion, J;Ségal-Bendirdjian, E
凋亡程序的诱导和执行通常被认为是通过半胱天冬酶激活的层次介导的。通过使用从L1210细胞系获得的两种细胞变体（L1210/S和L1210/0），我们先前已经表明星形孢菌素通过半胱天冬酶依赖性和半胱天冬酶非依赖性途径诱导凋亡性细胞死亡。两种途径通常共存于L1210/S细胞中，而L1210/0细胞缺乏激活半胱天冬酶的能力，尽管证实存在半胱天冬酶原-3和-9。在这里，我们表明，这种缺陷的半胱天冬酶的激活是由于机制，如细胞色素c的释放，非功能性半胱天冬酶的表达，或存在的内源性抑制剂的情况下，但从细胞凋亡蛋白酶激活蛋白-1（APAF-1）的表达的损失的结果。这种APAF-1蛋白的缺失是由于基因组和转录水平的多重改变。然而，尽管APAF-1的缺乏延迟了凋亡程序，但并不妨碍其执行。重要的是，在这些细胞中，凋亡不仅以APAF-1非依赖性方式发生，而且在不存在caspase-3和-9活化的情况下发生。总之，这些研究结果提供了证据，细胞凋亡可能发生通过替代信号通路独立的APAF-1的表达和完全解离的任何半胱天冬酶处理。因此，L1210/0变异亚系为阐明这些途径提供了有价值的工具。
Induction and execution of apoptosis programs are generally believed to be mediated through a hierarchy of caspase activation. By using two cellular variants obtained from the L1210 cell line (L1210/S and L1210/0), we have shown previously that staurosporine induces apoptotic cell death through both caspase-dependent and caspase-independent pathways. Both pathways normally coexisted in L1210/S cells, whereas L1210/0 cells lacked the ability to activate caspases despite the confirmed presence of both procaspase-3 and -9. Here we show that this defect in caspase activation is not due to mechanisms such as an absence of cytochrome c release, the expression of non-functional caspases, or the presence of an endogenous inhibitor but results from the loss of apoptosis protease activator protein-1 (APAF-1) expression. This absence of APAF-1 protein results from multiple alterations at both genomic and transcriptional levels. However, although this lack of APAF-1 delays the apoptotic program, it does not hamper its execution. Importantly, in these cells, apoptosis develops not only in an APAF-1-independent way but also in the absence of caspase-3 and -9 activation. Altogether these findings provide evidence that apoptosis may occur through alternative signaling pathways independent of APAF-1 expression and totally dissociated from any caspase processing. Therefore, the L1210/0 variant subline provides a valuable tool for the elucidation of these pathways.