Oxidative modification of caspase-9 facilitates its activation via disulfide-mediated interaction with Apaf-1
Oxidative modification of caspase-9 facilitates its activation via disulfide-mediated interaction with Apaf-1
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DOI：
10.1038/cr.2009.19
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发表时间：
2009-04
期刊：
影响因子：
44.1
通讯作者：
Y. Zuo;B. Xiang;Jie Yang;Xuxu Sun;Yumei Wang;Hui Cang;Jing Yi
中科院分区：
文献类型：
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作者：
Y. Zuo;B. Xiang;Jie Yang;Xuxu Sun;Yumei Wang;Hui Cang;Jing Yi
已知细胞内活性氧（ROS）调节细胞凋亡。线粒体凋亡级联中的起始caspase-9的活化与ROS密切相关，但ROS是否通过直接氧化修饰调节caspase-9尚不清楚。本研究旨在阐明ROS介导caspase-9活化的分子机制。我们的研究结果表明，细胞的氧化状态促进caspase-9的激活。过氧化氢处理引起caspase-9的活化和凋亡，并通过二硫键形成促进caspase-9和凋亡蛋白酶活化因子1（Apaf-1）之间的相互作用。此外，在体外无二硫键的系统中，硫醇-氧化剂二酰胺通过促进二硫键连接的复合物的形成来促进胱天蛋白酶-9的自切割和胱天蛋白酶-9/Apaf-1相互作用。最后，caspase-9的C403点突变通过消除二硫键的形成而损害H2 O2促进的caspase-9活化和与Apaf-1的相互作用。细胞色素c和C403 S突变体之间的关联明显弱于细胞色素c和野生型半胱天冬酶-9之间的关联，表明半胱天冬酶-9的氧化修饰有助于氧化应激下的溶酶体形成。总之，ROS对caspase-9的氧化修饰可以介导其与Apaf-1的相互作用，从而促进其自身切割和活化。这一机制可能有助于氧化应激下的溶酶体形成和caspase-9活化。
Intracellular reactive oxygen species (ROS) are known to regulate apoptosis. Activation of caspase-9, the initial caspase in the mitochondrial apoptotic cascade, is closely associated with ROS, but it is unclear whether ROS regulate caspase-9 via direct oxidative modification. The present study aims to elucidate the molecular mechanisms by which ROS mediate caspase-9 activation. Our results show that the cellular oxidative state facilitates caspase-9 activation. Hydrogen peroxide treatment causes the activation of caspase-9 and apoptosis, and promotes an interaction between caspase-9 and apoptotic protease-activating factor 1 (Apaf-1) via disulfide formation. In addition, in an in vitro mitochondria-free system, the thiol-oxidant diamide promotes auto-cleavage of caspase-9 and the caspase-9/Apaf-1 interaction by facilitating the formation of disulfide-linked complexes. Finally, a point mutation at C403 of caspase-9 impairs both H 2 O 2-promoted caspase-9 activation and interaction with Apaf-1 through the abolition of disulfide formation. The association between cytochrome c and the C403S mutant is significantly weaker than that between cytochrome c and wild-type caspase-9, indicating that oxidative modification of caspase-9 contributes to apoptosome formation under oxidative stress. Taken together, oxidative modification of caspase-9 by ROS can mediate its interaction with Apaf-1, and can thus promote its auto-cleavage and activation. This mechanism may facilitate apoptosome formation and caspase-9 activation under oxidative stress.