Different contribution of BH3-only proteins and caspases to doxorubicin-induced apoptosis in p53-deficient leukemia cells
Different contribution of BH3-only proteins and caspases to doxorubicin-induced apoptosis in p53-deficient leukemia cells
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DOI：
10.1016/j.bcp.2010.02.010
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发表时间：
2010-06-15
影响因子：
5.8
通讯作者：
Marzo, Isabel
中科院分区：
文献类型：
--
作者：
Lopez-Royuela, Nuria;Perez-Galan, Patricia;Marzo, Isabel
Bcl-2家族蛋白是内在凋亡途径的关键调节因子，促进（Bax、巴克、仅BH 3）或抑制（Bcl-2、Bcl-x（L）、Mcl-1、A1）致凋亡因子的线粒体释放。半胱天冬酶在这一过程中的作用是一个有争议的问题。我们分析了在两个p53缺陷型白血病细胞系Jurkat和U937中，多柔比星引发的细胞凋亡诱导阶段中半胱天冬酶和Bcl-2家族蛋白的相对贡献。首先，我们已经发现，半胱天冬酶是阿霉素诱导的细胞凋亡的诱导阶段，在两个细胞系，但他们需要加快在Jurkat细胞，不表达Bax的执行阶段。因此，下调巴克表达的siRNA显着阻止阿霉素诱导的Jurkat细胞凋亡，但不是在U937细胞。用siRNA降低Mcl-1蛋白水平增加了两种细胞系对凋亡的敏感性。此外，我们的研究结果表明，BH 3-only蛋白对细胞凋亡的贡献是细胞系特异性的。在Jurkat细胞中，同时沉默Bim和CD 4A对于减少阿霉素诱导的细胞凋亡是必要的。在U937细胞中，Bim或Noxa的沉默降低了对阿霉素的敏感性。免疫沉淀实验放弃了Mcl-1和巴克在两种细胞系之间的相互作用，并强调了Bim和Bak A作为Bax/巴克激活介质的作用。(C)2010年爱思唯尔公司All rights reserved.
Bcl-2 family proteins are key regulators of the intrinsic apoptotic pathway, either facilitating (Bax, Bak, BH3-only) or inhibiting (Bcl-2, Bcl-x(L), Mcl-1, A1) mitochondrial release of apoptogenic factors. The role of caspases in this process is a matter of controversy. We have analyzed the relative contribution of caspases and Bcl-2 family of proteins in the induction phase of apoptosis triggered by doxorubicin in two p53-deficient leukemia cell lines, Jurkat and U937. First, we have found that caspases are dispensable for the induction phase of doxorubicin-induced apoptosis in both cell lines but they are needed to speed up the execution phase in Jurkat cells, not expressing Bax. Thus, down-regulation of Bak expression by siRNA significantly prevented doxorubicin-induced apoptosis in Jurkat but not in U937 cells. Reduction of Mcl-1 protein levels with siRNA increased sensitivity to apoptosis in both cell lines. Moreover, our results indicate that the contribution of BH3-only proteins to apoptosis is cell line specific. In Jurkat cells simultaneous silencing of Bim and PUMA was necessary to reduce doxorubicin-induced apoptosis. In U937 cells silencing of Bim or Noxa reduced sensitivity to doxorubicin. Immunoprecipitation experiments discarded an interaction between Mcl-1 and Bak in both cell lines and underscored the role of Bim and PUMA as mediators of Bax/Bak activation. (C) 2010 Elsevier Inc. All rights reserved.