System xc- and Thioredoxin Reductase 1 Cooperatively Rescue Glutathione Deficiency
System xc- and Thioredoxin Reductase 1 Cooperatively Rescue Glutathione Deficiency
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DOI：
10.1074/jbc.m110.121327
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发表时间：
2010-07-16
影响因子：
4.8
通讯作者：
Conrad, Marcus
中科院分区：
文献类型：
--
作者：
Mandal, Pankaj Kumar;Seiler, Alexander;Conrad, Marcus
GSH是哺乳动物细胞中外源物质的主要抗氧化剂和解毒剂。细胞内GSH的显著降低经常与诸如缺血/再灌注损伤等病理条件以及包括糖尿病、动脉粥样硬化和神经变性在内的退行性疾病有关。虽然GSH对于生存是必不可少的，但GSH缺乏的有害影响通常可以通过含有硫醇的抗氧化剂来补偿。使用三种基因定义的细胞系统，我们在这里展示了强制表达XCT，半胱氨酸/谷氨酸逆向转运体的底物特异性亚单位，在γ-谷氨酰半胱氨酸合成酶敲除细胞中的强制表达通过增加细胞内的半胱氨酸摄取，导致细胞内和令人惊讶的高的细胞外半胱氨酸水平来拯救GSH缺乏。此外，我们提供的证据表明，在谷胱甘肽缺乏的情况下，胞内硫氧还蛋白/硫氧还蛋白还原酶系统对细胞处理细胞内过量的胱氨酸起着至关重要的作用。我们的研究提供了第一个证据，当设计针对特定氧化还原酶的治疗原理来对抗与GSH缺乏相关的疾病时，可以通过内在的遗传机制来拯救GSH缺乏症。
GSH is the major antioxidant and detoxifier of xenobiotics in mammalian cells. A strong decrease of intracellular GSH has been frequently linked to pathological conditions like ischemia/reperfusion injury and degenerative diseases including diabetes, atherosclerosis, and neurodegeneration. Although GSH is essential for survival, the deleterious effects of GSH deficiency can often be compensated by thiol-containing antioxidants. Using three genetically defined cellular systems, we show here that forced expression of xCT, the substrate-specific subunit of the cystine/glutamate antiporter, in gamma-glutamylcysteine synthetase knock-out cells rescues GSH deficiency by increasing cellular cystine uptake, leading to augmented intracellular and surprisingly high extracellular cysteine levels. Moreover, we provide evidence that under GSH deprivation, the cytosolic thioredoxin/thioredoxin reductase system plays an essential role for the cells to deal with the excess amount of intracellular cystine. Our studies provide first evidence that GSH deficiency can be rescued by an intrinsic genetic mechanism to be considered when designing therapeutic rationales targeting specific redox enzymes to combat diseases linked to GSH deprivation.