Thioredoxin Reductase-2 Is Essential for Keeping Low Levels of H2O2 Emission from Isolated Heart Mitochondria
Thioredoxin Reductase-2 Is Essential for Keeping Low Levels of H2O2 Emission from Isolated Heart Mitochondria
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DOI：
10.1074/jbc.m111.284612
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发表时间：
2011-09-23
影响因子：
4.8
通讯作者：
Paolocci, Nazareno
中科院分区：
文献类型：
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作者：
Stanley, Brian A.;Sivakumaran, Vidhya;Paolocci, Nazareno
呼吸线粒体持续产生H2 O2。当生产超过清除，H2 O2排放发生，危及细胞功能。线粒体过氧化物酶peroxiredoxin-3使用硫氧还蛋白-2（Trx 2）和硫氧还蛋白还原酶-2（TrxR 2）提供的NADPH的还原当量将H2 O2还原为水。在这里，这个线粒体硫氧还蛋白系统的控制过氧化氢排放的贡献进行了研究，在分离的线粒体和心肌细胞从小鼠或豚鼠心脏。通过添加谷氨酸/苹果酸使线粒体通电导致氧化与还原Trx 2的比率降低10倍。这种氧化还原状态的转变伴随着NAD（P）H的增加，并且依赖于TrxR 2活性。金诺芬在分离的线粒体中抑制TrxR 2导致H2 O2排放增加，这是在正向和反向电子传递下观察到的效果。这种效应不依赖于NAD（P）H或膜电位的变化。金诺芬的作用在心肌细胞中重现;超氧化物和H2 O2水平增加，但类似地，对NAD（P）H或膜电位没有影响。这些数据表明，线粒体的破坏增加了TrxR 2/Trx 2系统的抗氧化潜力，并且TrxR 2的抑制通过与其他氧化还原对的变化无关的机制导致H2 O2排放增加。
Respiring mitochondria produce H2O2 continuously. When production exceeds scavenging, H2O2 emission occurs, endangering cell functions. The mitochondrial peroxidase peroxiredoxin-3 reduces H2O2 to water using reducing equivalents from NADPH supplied by thioredoxin-2 (Trx2) and, ultimately, thioredoxin reductase-2 (TrxR2). Here, the contribution of this mitochondrial thioredoxin system to the control of H2O2 emission was studied in isolated mitochondria and cardiomyocytes from mouse or guinea pig heart. Energization of mitochondria by the addition of glutamate/malate resulted in a 10-fold decrease in the ratio of oxidized to reduced Trx2. This shift in redox state was accompanied by an increase in NAD(P) H and was dependent on TrxR2 activity. Inhibition of TrxR2 in isolated mitochondria by auranofin resulted in increased H2O2 emission, an effect that was seen under both forward and reverse electron transport. This effect was independent of changes in NAD(P) H or membrane potential. The effects of auranofin were reproduced in cardiomyocytes; superoxide and H2O2 levels increased, but similarly, there was no effect on NAD(P) H or membrane potential. These data show that energization of mitochondria increases the antioxidant potential of the TrxR2/Trx2 system and that inhibition of TrxR2 results in increased H2O2 emission through a mechanism that is independent of changes in other redox couples.