Forced expression of survivin-2B abrogates mitotic cells and induces mitochondria-dependent apoptosis by blockade of tubulin polymerization and modulation of Bcl-2, Bax, and survivin
Forced expression of survivin-2B abrogates mitotic cells and induces mitochondria-dependent apoptosis by blockade of tubulin polymerization and modulation of Bcl-2, Bax, and survivin
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DOI：
10.1074/jbc.m705161200
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发表时间：
2007-09-14
影响因子：
4.8
通讯作者：
Li, Fengzhi
中科院分区：
文献类型：
--
作者：
Ling, Xiang;Cheng, Qiuying;Li, Fengzhi
先前已经表明，生存素和生存素剪接变体生存素-2B都定位于线粒体中。尽管生存素阻断线粒体介导的细胞凋亡的机制已得到广泛研究，但生存素-2B在调节细胞凋亡中的作用尚未得到很好的定义。在本研究中，我们报告说，除了线粒体，生存素-2B也定位于微管组织中心（MTOC），并在其他生存素亚型（即生存素和生存素-三角洲Ex 3）相比，作为一个促凋亡分子的行为。我们发现，生存素-2B的强制表达阻断微管蛋白聚合，消融有丝分裂细胞，并诱导凋亡依赖性细胞凋亡。Survivin-2B诱导的凋亡由线粒体Smac释放、caspase-9和3的激活以及线粒体电位的丧失指示，而caspase-8保持无活性。对由生存素-2B的强制表达诱导的凋亡相关事件的机制的进一步分析揭示了线粒体中促生存因子Bcl-2的下调和促凋亡因子Bax的上调，而凋亡诱导因子（AIF）保持不变。我们的研究进一步表明，紫杉醇（紫杉醇）治疗癌细胞不仅上调生存素，而且下调生存素-2B，生存素-2B的强制表达使细胞对紫杉醇诱导的细胞生长抑制和细胞死亡敏感，而通过生存素-2B特异性siRNA沉默内源性生存素-2B转录本使细胞对紫杉醇治疗产生抗性。这些发现推进了我们目前对生存素-2B的认识，并可能有助于开发癌症治疗的新方法。
It has been previously shown that both survivin and the survivin splice variant survivin-2B are localized in mitochondria. Whereas the mechanism involved in blockade of mitochondria-mediated apoptosis by survivin has been extensively studied, the role of survivin-2B in regulation of apoptosis has not been well defined. In the present study, we report that in addition to mitochondria, survivin-2B is also localized in the microtubule organization center (MTOC) and, in contrast to other survivin isoforms (i.e. survivin and survivin-Delta Ex3), behaves as a proapoptotic molecule. We show that forced expression of survivin-2B blocks tubulin polymerization, ablates mitotic cells, and induces mitochondria-dependent apoptosis. The mitochondria-mediated apoptosis induced by survivin-2B was indicated by Smac release from mitochondria, activation of caspases 9 and 3, and loss of mitochondrial potential, while caspase-8 remained inactive. Further analysis of the mechanism for the mitochondria-associated events of apoptosis induced by forced expression of survivin-2B revealed down-regulation of the pro-survival factor Bcl-2 and up-regulation of the pro-apoptotic factor Bax in mitochondria, while the apoptosis-inducing factor (AIF) remains unchanged. Our studies further showed that taxol (paclitaxel) treatment of cancer cells not only up-regulates survivin but also down-regulates survivin-2B and that forced expression of survivin-2B sensitizes cells to taxol-induced cell growth inhibition and cell death, while silencing of endogenous survivin-2B transcripts by survivin-2B-specific siRNA made cells resistant to taxol treatment. These findings advance our current knowledge about survivin-2B and may help to develop novel approaches for cancer treatment.