Redox activation of aldose reductase in the ischemic heart
Redox activation of aldose reductase in the ischemic heart
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DOI：
10.1074/jbc.m600837200
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发表时间：
2006-06-02
影响因子：
4.8
通讯作者：
Bhatnagar, Aruni
中科院分区：
文献类型：
--
作者：
Kaiserova, Karin;Srivastava, Sanjay;Bhatnagar, Aruni
醛糖还原酶(AR)可降低细胞毒性醛和由脂质过氧化产生的醛的谷胱甘肽结合物。它的抑制已被证明增加氧化损伤和取消缺血预适应的晚期阶段。然而，缺血调节AR活性的机制仍不清楚。在此，我们报道了大鼠心脏在体或在体缺血后，AR活性增加了2-4倍。再灌流不能进一步增强AR活性。激活增加了酶的V-max而不影响K-m，并降低了酶对山梨醇抑制的敏感性。用清除自由基的硫醇、N-(2-硫代-固氮基)甘氨酸或超氧化物歧化酶模拟物TIron或用二硫苏糖醇处理匀浆，可以防止酶的激活。在体外，重组酶被H_2O_2激活，被激活的酶，而不是天然的酶，与磺酸特异的试剂二美酮形成共价加合物。对缺血区心脏匀浆的酶活性有抑制作用，但对非缺血区心脏匀浆酶活性无明显影响。通过双向电泳和随后的基质辅助激光解吸电离飞行时间/质谱分析从冠状动脉闭塞的心脏中分离出蛋白质，发现在Cys-298和Cys-303处形成了磺酸。这些数据表明，缺血心脏中形成的活性氧通过将半胱氨酸残基修饰为亚磺酸来激活AR。
Aldose reductase (AR) reduces cytotoxic aldehydes and glutathione conjugates of aldehydes derived from lipid peroxidation. Its inhibition has been shown to increase oxidative injury and abolish the late phase of ischemic preconditioning. However, the mechanisms by which ischemia regulates AR activity remain unclear. Herein, we report that rat hearts subjected to ischemia, in situ or ex vivo, display a 2-4-fold increase in AR activity. The AR activity was not further enhanced by reperfusion. Activation increased V-max of the enzyme without affecting the K-m and decreased the sensitivity of the enzyme to inhibition by sorbinil. Enzyme activation could be prevented by pretreating the hearts with the radical scavenging thiol, N-(2-mercaptoproprionyl) glycine or the superoxide dismutase mimetic, Tiron, or by treating homogenates with dithiothreitol. In vitro, the recombinant enzyme was activated upon treatment with H2O2 and the activated, but not the native enzyme, formed a covalent adduct with the sulfenic acid-specific reagent dimedone. The enzyme activity in the ischemic, but not the non-ischemic heart homogenates was inhibited by dimedone. Separation of proteins from hearts subjected to coronary occlusion by two-dimensional electrophoresis and subsequent matrix-assisted laser desorption ionization time-of-flight/mass spectrometry analysis revealed the formation of sulfenic acids at Cys-298 and Cys-303. These data indicate that reactive oxygen species formed in the ischemic heart activate AR by modifying its cysteine residues to sulfenic acids.