Nucleophosmin is a novel Bax chaperone that regulates apoptotic cell death
Nucleophosmin is a novel Bax chaperone that regulates apoptotic cell death
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DOI：
10.1038/sj.onc.1210044
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发表时间：
2007-04-19
期刊：
影响因子：
8
通讯作者：
Sharkey, J.
中科院分区：
文献类型：
--
作者：
Kerr, L. E.;Birse-Archbold, J-L A.;Sharkey, J.
促凋亡b细胞淋巴瘤-2家族蛋白Bax是内在凋亡通路的关键调控点。然而，控制Bax活化和转位到线粒体过程的因素尚未完全确定和表征。我们使用与Bax的线粒体靶向区域相对应的肽进行亲和层析，该区域通常被隔离在非活性结构中。鉴定了分子伴侣核磷蛋白。通过基质辅助激光解吸/电离飞行时间质谱分析发现了一种新的bax结合蛋白。互反共免疫沉淀和接近试验证实了Bax-核蛋白蛋白-蛋白质相互作用，并证实核蛋白仅与激活的构象改变的Bax结合。在细胞凋亡模型中，共聚焦显微镜显示，核磷蛋白从核仁向细胞质转移先于Bax运动。具体。通过线粒体细胞色素c的释放和caspase级联的激活来测量，RNAi抑制核磷蛋白表达可减轻细胞凋亡。在小鼠缺血性中风模型中，亚细胞分离研究证实了这一点。核磷蛋白易位发生在3小时内，在Bax易位之前，但在Bax构象改变发生之后。因此，我们已经阐明了一种新的分子机制，即Bax被激活并易位到线粒体以协调线粒体功能障碍和凋亡细胞死亡，这为治疗干预开辟了新的途径。
The proapoptotic B-cell lymphoma-2 family protein Bax is a key regulatory point in the intrinsic apoptotic pathway. However, the factors controlling the process of Bax activation and translocation to mitochondria have yet to be fully identified and characterized. We performed affinity chromatography using peptides corresponding to the mitochondrial-targeting region of Bax, which is normally sequestered within the inactive structure. The molecular chaperone nucleophosmin was identified. ed as a novel Bax-binding protein by matrix- assisted laser desorption/ionization time-of-flight mass spectrometry. Reciprocal co-immunoprecipitation and proximity assays con. confirmed the Bax-nucleophosmin protein-protein interaction and verified that nucleophosmin only bound to activated conformationally altered Bax. Confocal microscopy in a cell-based apoptosis model, demonstrated that nucleophosmin translocation from nucleolus to cytosol preceded Bax movement. Specific. c knockdown of nucleophosmin expression using RNAi attenuated apoptosis as measured by mitochondrial cytochrome c release and activation of the caspase cascade. In a mouse model of ischaemic stroke, subcellular fractionation studies veri. ed that nucleophosmin translocation occurred within 3 h, at a time before Bax translocation but after Bax conformational changes have occurred. Thus, we have elucidated a novel molecular mechanism whereby Bax becomes activated and translocates to the mitochondria to orchestrate mitochondrial dysfunction and apoptotic cell death, which opens new avenues for therapeutic intervention.