S-nitrosylation of Bcl-2 inhibits its ubiquitin-proteasomal degradation -: A novel antiapoptotic mechanism that suppresses apoptosis
S-nitrosylation of Bcl-2 inhibits its ubiquitin-proteasomal degradation -: A novel antiapoptotic mechanism that suppresses apoptosis
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DOI：
10.1074/jbc.m602551200
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发表时间：
2006-11-10
影响因子：
4.8
通讯作者：
Rojanasakul, Yon
中科院分区：
文献类型：
--
作者：
Azad, Neelam;Vallyathan, Val;Rojanasakul, Yon
Bcl-2是线粒体死亡途径的关键凋亡调节蛋白，其功能依赖于其表达水平。虽然Bcl-2的表达受多种机制控制，但翻译后修饰，如泛素化和蛋白酶体降解，已成为Bcl-2功能的重要调节因子。然而，这种调节的基本机制尚不清楚。我们在这里报告，Bcl-2经历S-亚硝基化内源性一氧化氮（NO）在响应多种凋亡介质，这种修饰抑制泛素-蛋白酶体降解Bcl-2。NO清除剂2-（4-carboxyphenyl）-4，4，5，5-tetramethylimidazoline-1-oxyl-3-oxide和NO合成酶抑制剂aminoguanidine抑制NO的产生可有效抑制Bcl-2的S-亚硝基化，增加其泛素化，促进铬（VI）诱导的细胞凋亡。相反，NO供体二亚丙基三胺NONOate和硝普钠显示相反的效果。NO对Bcl-2稳定性的影响与其去磷酸化无关。Bcl-2的突变分析进一步表明Bcl-2的两个半胱氨酸残基（Cys（158）和Cys（229））在S-亚硝基化过程中是重要的，并且这些半胱氨酸的突变完全抑制Bcl-2的S-亚硝基化。用其他应激诱导剂（包括Fas配体和丁硫醚亚砜）处理细胞也诱导Bcl-2 S-亚硝基化，表明这是在各种应激条件下调节Bcl-2稳定性和功能的普遍现象。这些发现表明NO的新功能及其对Bcl-2的调节，这为控制细胞凋亡和癌症发展提供了关键机制。
Bcl-2 is a key apoptosis regulatory protein of the mitochondrial death pathway whose function is dependent on its expression levels. Although Bcl-2 expression is controlled by various mechanisms, post-translational modifications, such as ubiquitination and proteasomal degradation, have emerged as important regulators of Bcl-2 function. However, the underlying mechanisms of this regulation are unclear. We report here that Bcl-2 undergoes S-nitrosylation by endogenous nitric oxide ( NO) in response to multiple apoptotic mediators and that this modification inhibits ubiquitin-proteasomal degradation of Bcl-2. Inhibition of NO production by the NO scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide and by NO synthase inhibitor aminoguanidine effectively inhibited S-nitrosylation of Bcl-2, increased its ubiquitination, and promoted apoptotic cell death induced by chromium ( VI). In contrast, the NO donors dipropylenetriamine NONOate and sodium nitroprusside showed opposite effects. The effect of NO on Bcl-2 stability was shown to be independent of its dephosphorylation. Mutational analysis of Bcl-2 further showed that the two cysteine residues of Bcl-2 (Cys(158) and Cys(229)) are important in the S-nitrosylation process and that mutations of these cysteines completely inhibited Bcl-2 S-nitrosylation. Treatment of the cells with other stress inducers, including Fas ligand and buthionine sulfoxide, also induced Bcl-2 S-nitrosylation, suggesting that this is a general phenomenon that regulates Bcl-2 stability and function under various stress conditions. These findings indicate a novel function of NO and its regulation of Bcl-2, which provides a key mechanism for the control of apoptotic cell death and cancer development.