Excitotoxic calcium overload in a subpopulation of mitochondria triggers delayed death in hippocampal neurons
Excitotoxic calcium overload in a subpopulation of mitochondria triggers delayed death in hippocampal neurons
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DOI：
10.1523/jneurosci.0531-04.2004
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发表时间：
2004-06-16
影响因子：
5.3
通讯作者：
Andrews, SB
中科院分区：
文献类型：
--
作者：
Pivovarova, NB;Nguyen, HV;Andrews, SB
在神经元中，兴奋性毒性刺激诱导线粒体钙超载和促凋亡蛋白的释放，其触发延迟的细胞死亡。然而，对促性腺激素释放的确切机制仍存在争议。为了表征线粒体钙负荷和细胞脆弱性之间的联系，并测试的假设，只有一个亚群的线粒体受损的钙超载释放aptogens，我们直接测量的浓度总钙（自由加结合）在个别线粒体和监测平行结构的变化和亚细胞定位的促凋亡细胞色素c NMDA过度刺激后，在培养的海马神经元。除了短暂的胞浆钙离子升高和Na+/K+稳态的扰动，NMDA刺激诱导线粒体发生剧烈的，但主要是可逆的变化，包括强烈的钙离子升高、膜电位去极化和可变的肿胀。大约三分之一的线粒体中基质Ca的升高（强烈肿胀），以及当Ca 2+进入被消除时没有肿胀，表明Ca超载的重要作用。NMDA暴露后不久，细胞色素c，通常定位于线粒体，成为弥漫性分布在细胞质中，符合外观严重肿胀的线粒体破裂外膜，在这些条件下，细胞色素c保留在完整的线粒体，这意味着它主要是从受损的线粒体释放。与线粒体Ca超载的作用一致，羰基氰化物对-（三氟甲氧基）苯腙减少Ca积累，阻止细胞色素c释放，并具有神经保护作用。这些结果支持了一种机制，其中延迟兴奋性毒性死亡涉及从钙超载线粒体的亚群释放糖原，而其他未受损的线粒体保持正常功能。
In neurons, excitotoxic stimulation induces mitochondrial calcium overload and the release of pro-apoptotic proteins, which triggers delayed cell death. The precise mechanisms of apoptogen release, however, remain controversial. To characterize the linkage between mitochondrial calcium load and cell vulnerability, and to test the hypothesis that only a subpopulation of mitochondria damaged by calcium overload releases apoptogens, we have measured directly the concentrations of total Ca ( free plus bound) in individual mitochondria and monitored in parallel structural changes and the subcellular localization of pro-apoptotic cytochrome c after NMDA overstimulation in cultured hippocampal neurons. Beyond transient elevation of cytosolic calcium and perturbation of Na+/K+ homeostasis, NMDA stimulation induced dramatic, but mainly reversible, changes in mitochondria, including strong calcium elevation, membrane potential depolarization, and variable swelling. Elevation of matrix Ca in the approximately one-third of mitochondria that were strongly swollen, as well as the absence of swelling when Ca2+ entry was abolished, indicate an essential role for Ca overload. Shortly after NMDA exposure, cytochrome c, normally localized to mitochondria, became diffusely distributed in the cytoplasm, coincident with the appearance of severely swollen mitochondria with ruptured outer membranes; under these conditions, cytochrome c was retained in intact mitochondria, implying that it was released mainly from damaged mitochondria. Consistent with the role of mitochondrial Ca overload, carbonyl cyanide p-(trifluoromethoxy) phenylhydrazone decreased Ca accumulation, prevented cytochrome c release, and was neuroprotective. These results support a mechanism in which delayed excitotoxic death involves apoptogen release from a subpopulation of calcium-overloaded mitochondria, whereas other, undamaged mitochondria maintain normal function.