Cleavage of Bcl-2 is an early event in chemotherapy-induced apoptosis of human myeloid leukemia cells
Cleavage of Bcl-2 is an early event in chemotherapy-induced apoptosis of human myeloid leukemia cells
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DOI：
10.1038/sj.leu.2401411
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发表时间：
1999-05-01
期刊：
影响因子：
11.4
通讯作者：
Zhivotovsky, B
中科院分区：
文献类型：
--
作者：
Fadeel, B;Hassan, Z;Zhivotovsky, B
原癌基因产物 Bcl-2 通过迄今未知的机制保护多种细胞类型免于凋亡。 Bcl-2 已被证明在某些（但不是全部）细胞凋亡事件中在死亡蛋白酶（半胱天冬酶）的上游发挥作用。使用髓系白血病细胞系 P39，我们报告了化疗诱导的内源性 Bcl-2 的 caspase 依赖性裂解。这些细胞的依托泊苷处理引发了 II 型和 III 型半胱天冬酶的时间依赖性激活以及 Bcl-2 的裂解，产生 23 kDa 的裂解片段。这种裂解产物的出现被通用 caspase 抑制剂 zVAD-fmk、III 型 caspase 抑制剂 IETD-fmk 和 caspase-9 选择性抑制剂 LEHD-fmk 阻断，而 II 型 caspase 抑制剂 DEVD-fmk 被证明效率相当低。 Bcl-2 裂解先于已知的 caspase-3 底物聚（ADP-核糖）聚合酶 (PARP) 以及 caspase-6 底物 iamin B 的裂解，表明在该实验模型中，Bcl-2 裂解是细胞凋亡级联中相对较早的事件。虽然获得了依托泊苷处理细胞的几个亚细胞区室中 Bcl-2 裂解的证据，但这种裂解主要在线粒体部分中检测到，从而为线粒体在细胞凋亡中的核心作用提供了进一步的支持。对这些骨髓性白血病细胞进行依托泊苷处理后，Caspase 介导的裂解可能是诱导凋亡时减弱 Bcl-2 功能的一种方法。
The proto-oncogene product Bcl-2 protects a wide variety of cell types from apoptosis via a hitherto unknown mechanism. Bcl-2 has been shown to function upstream of the death proteases (caspases) in some, but not all, occurrences of apoptotic cell death. Using the myeloid leukemic cell line P39 we report the chemotherapy-induced caspase-dependent cleavage of endogenous Bcl-2. Etoposide treatment of these cells triggered a time-dependent activation of type II and type III caspases and cleavage of Bcl-2 yielding a 23 kDa cleavage fragment. The emergence of this cleavage product was blocked by the general caspase inhibitor zVAD-fmk, as well as the type ill caspase inhibitor IETD-fmk and the caspase-9-selective inhibitor LEHD-fmk, while the type II caspase inhibitor DEVD-fmk proved considerably less efficient. Bcl-2 cleavage preceded cleavage of the known caspase-3 substrate, poly(ADP-ribose) polymerase (PARP), as well as that of the caspase-6 substrate, iamin B, indicating that Bcl-2 cleavage is a relatively early event in the apoptosis cascade in this experimental model. While evidence for cleavage of Bcl-2 in several subcellular compartments of etoposide-treated cells was obtained, this cleavage was detected predominantly in the mitochondrial fraction, thus providing further support for the central role of mitochondria in apoptosis. Caspase-mediated cleavage following etoposide treatment of these myeloid leukemic cells may represent a means for the attenuation of Bcl-2 function upon apoptosis induction.