Mitochondrial superoxide radicals mediate programmed cell death in Trypanosoma cruzi:: cytoprotective action of mitochondrial iron superoxide dismutase overexpression
Mitochondrial superoxide radicals mediate programmed cell death in Trypanosoma cruzi:: cytoprotective action of mitochondrial iron superoxide dismutase overexpression
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DOI：
10.1042/bj20061281
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发表时间：
2007-04-15
影响因子：
4.1
通讯作者：
Radi, Rafael
中科院分区：
文献类型：
--
作者：
Piacenza, Lucia;Irigoin, Florencia;Radi, Rafael
克氏锥虫在适当的刺激下发生程序性细胞死亡，其机制尚不清楚。在本研究中，我们表明，刺激PCD在克氏锥虫外鞭毛体FHS（新鲜人血清）的结果在快速（< 1小时）的磷脂酰丝氨酸和耗尽的低分子量硫醇二氢锥硫酮和谷胱甘肽的外化。同时，通过EPR和使用DMPO（5，5-二甲基吡咯啉-N-氧化物）的自由基的免疫自旋捕获以及通过戊糖磷酸途径的葡萄糖通量的增加建立了氧化剂的增强生成。在早期（< 20分钟），观察到线粒体膜电位的变化和呼吸抑制，可能是由于ADP/ATP与细胞质交换的损害，有利于O-2（中心点-）的产生。线粒体O-2（中心点-）生产的加速率检测的氧化还原敏感的线粒体顺乌头酸酶的失活和氧化的线粒体靶向探针（MitoSOX）。重要的是，过表达线粒体FeSOD（铁超氧化物歧化酶）的寄生虫对PCD刺激的抵抗力更强，明确表明线粒体O-2（中心点-）参与信号传导过程。总之，FHS诱导的T cruzi PCD涉及线粒体功能障碍，导致O-2（中心点-）形成增强，导致细胞氧化应激条件，触发PCD级联反应的启动;此外，线粒体FeSOD的过表达，这也是在metacyclogenesis过程中观察到的，导致细胞保护作用。
Trypanosoma cruzi undergo PCD (programmed cell death) under appropriate stimuli, the mechanisms of which remain to be established. In the present study, we show that stimulation of PCD in T cruzi epimastigotes by FHS (fresh human serum) results in rapid (< 1 h) externalization of phosphatidylserine and depletion of the low molecular mass thiols dihydrotrypanothione and glutathione. Concomitantly, enhanced generation of oxidants was established by EPR and immuno-spin trapping of radicals using DMPO (5,5-dimethylpyrroline-N-oxide) and augmentation of the glucose flux through the pentose phosphate pathway. In the early period (< 20 min), changes in mitochondrial membrane potential and inhibition of respiration, probably due to the impairment of ADP/ATP exchange with the cytosol, were observed, conditions that favour the generation of O-2(center dot-). Accelerated rates of mitochondrial O-2(center dot-) production were detected by the inactivation of the redox-sensitive mitochondrial aconitase and by oxidation of a mitochondrial-targeted probe (MitoSOX). Importantly, parasites overexpressing mitochondrial FeSOD (iron superoxide dismutase) were more resistant to the PCD stimulus, unambiguously indicating the participation of mitochondrial O-2(center dot-) in the signalling process. In summary, FHS-induced PCD in T cruzi involves mitochondrial dysfunction that causes enhanced O-2(center dot-) formation, which leads to cellular oxidative stress conditions that trigger the initiation of PCD cascades; moreover, overexpression of mitochondrial FeSOD, which is also observed during metacyclogenesis, resulted in cytoprotective effects.