Calpain I induces cleavage and release of apoptosis-inducing factor from isolated mitochondria
Calpain I induces cleavage and release of apoptosis-inducing factor from isolated mitochondria
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DOI：
10.1074/jbc.m413269200
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发表时间：
2005-02-25
影响因子：
4.8
通讯作者：
Nicholls, DG
中科院分区：
文献类型：
--
作者：
Polster, BM;Basañez, G;Nicholls, DG
凋亡诱导因子（AIF）从线粒体到细胞核的易位与皮质神经元谷氨酸兴奋毒性的机制有关，并在啮齿动物急性脑损伤后的体内观察到。然而，AIF向细胞核再分布的机制和时间过程仍存在很大争议。由于细胞内钙升高是神经元细胞死亡最普遍的特征之一，本研究验证了钙活化蛋白酶calpain切割AIF介导其从线粒体释放的假设。重组AIF的前体和成熟形式均在体外被钙蛋白酶I在氨基末端附近切割。截断的Bid可通过线粒体外膜诱导离体肝或脑线粒体释放细胞色素c，但仅在活性钙蛋白酶存在时诱导AIF释放。calpeptin对calpain的酶促抑制阻止了AIF的释放，这表明AIF的释放需要蛋白水解活性。Calpeptin和线粒体通透性过渡孔拮抗剂环孢素A也能抑制钙诱导的AIF从小鼠肝脏线粒体释放，提示内源性线粒体calpain参与了通透性过渡过程中AIF的释放。AIF的切割直接降低了其与线粒体内膜组成的纯脂质囊泡的关联。综上所述，这些结果确定了一种涉及钙蛋白酶加工的AIF释放新机制，并确定了细胞保护干预的潜在分子检查点。
The translocation of apoptosis-inducing factor (AIF) from mitochondria to the nucleus has been implicated in the mechanism of glutamate excitotoxicity in cortical neurons and has been observed in vivo following acute rodent brain injuries. However, the mechanism and time course of AIF redistribution to the nucleus is highly controversial. Because elevated intracellular calcium is one of the most ubiquitous features of neuronal cell death, this study tested the hypothesis that cleavage of AIF by the calcium-activated protease calpain mediates its release from mitochondria. Both precursor and mature forms of recombinant AIF were cleaved near the amino terminus by calpain I in vitro. Mitochondrial outer membrane permeabilization by truncated Bid induced cytochrome c release from isolated liver or brain mitochondria but only induced AIF release in the presence of active calpain. Enzymatic inhibition of calpain by calpeptin precluded AIF release, demonstrating that proteolytic activity was required for release. Calpeptin and the mitochondrial permeability transition pore antagonist cyclosporin A also inhibited calcium-induced AIF release from mouse liver mitochondria, implicating the involvement of an endogenous mitochondrial calpain in release of AIF during permeability transition. Cleavage of AIF directly decreased its association with pure lipid vesicles of mitochondrial inner membrane composition. Taken together, these results define a novel mechanism of AIF release involving calpain processing and identify a potential molecular checkpoint for cytoprotective interventions.