Mitochondrial respiratory chain and thioredoxin reductase regulate intermembrane Cu, Zn-superoxide dismutase activity:: implications for mitochondrial energy metabolism and apoptosis
Mitochondrial respiratory chain and thioredoxin reductase regulate intermembrane Cu, Zn-superoxide dismutase activity:: implications for mitochondrial energy metabolism and apoptosis
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DOI：
10.1042/bj20061809
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发表时间：
2007-07-01
影响因子：
4.1
通讯作者：
Cadenas, Enrique
中科院分区：
文献类型：
--
作者：
Inarrea, Pedro;Moini, Hadi;Cadenas, Enrique
IMS（膜间空间）SOD1 （Cu/ zn超氧化物歧化酶）在分离的完整大鼠肝脏线粒体中失活，并在其关键巯基氧化修饰后被激活。本研究旨在确定与IMS SOD1活性调控有关的生化途径，并评估其功能状态对关键线粒体事件的影响。外源H2O3 （5 μ M）激活完整线粒体中的SOD1。然而，无论是单独的H2O2还是线粒体过氧化物还蛋白III存在时的H2O2都不能激活SOD1， SOD1从线粒体中纯化出来，随后被二硫苏糖醇还原为无活性状态。还原酶与超氧化物生成系统、黄嘌呤和黄嘌呤氧化酶孵育后被激活。在完整的线粒体中，SOD1激活的程度和持续时间与线粒体超氧化物的产生呈负相关。Western blotting证实线粒体IMS中存在TxrR-1（硫氧还蛋白还原酶-1）。TxrR-1、CDNB（1-氯-2,4二硝基苯）或金嘌呤抑制剂可延长H(2)O（2-）诱导完整线粒体中SOD1活性的持续时间。TxrR-1灭活了活性氧化状态下从线粒体中纯化的SOD1。外源性H2O2激活IMS SOD1可延迟CaCl2诱导的跨膜电位丧失，降低细胞色素c的释放，并显著防止超氧化物诱导的完整线粒体在状态3呼吸时乌头酶活性丧失。这些发现表明H2O2、超氧化物和txr -1可可逆地调节IMS SOD1活性，并且该活性酶与保护重要的线粒体功能有关。
IMS (intermembrane space) SOD1 (Cu/Zn-superoxide dismutase) is inactive in isolated intact rat liver mitochondria and is activated following oxidative modification of its critical thiol groups. The present study aimed to identify biochemical pathways implicated in the regulation of IMS SOD1 activity and to assess the impact of its functional state on key mitochondrial events. Exogenous H2O3 (5 mu M) activated SOD1 in intact mitochondria. However, neither H2O2 alone nor H2O2 in the presence of mitochondrial peroxiredoxin III activated SOD1, which was purified from mitochondria and subsequently reduced by dithiothreitol to an inactive state. The reduced enzyme was activated following incubation with the superoxide generating system, xanthine and xanthine oxidase. In intact mitochondria, the extent and duration of SOD1 activation was inversely correlated with mitochondrial superoxide production. The presence of TxrR-1 (thioredoxin reductase-1) was demonstrated in the mitochondrial IMS by Western blotting. Inhibitors of TxrR-1, CDNB (1-chloro-2,4dinitrobenzene) or auranofin, prolonged the duration of H(2)O(2-)induced SOD1 activity in intact mitochondria. TxrR-1 inactivated SOD1 purified from mitochondria in an active oxidized state. Activation of IMS SOD1 by exogenous H2O2 delayed CaCl2- induced loss of transmembrane potential, decreased cytochrome c release and markedly prevented superoxide-induced loss of aconitase activity in intact mitochondria respiring at state-3. These findings suggest that H2O2, superoxide and TxrR-1 regulate IMS SOD1 activity reversibly, and that the active enzyme is implicated in protecting vital mitochondrial functions.