The reactive oxygen species- and Michael acceptor-inducible human aldo-keto reductase AKR1C1 reduces the α,β-unsaturated aldehyde 4-hydroacy-2-nonenal to 1,4-dihydroxy-2-nonene
The reactive oxygen species- and Michael acceptor-inducible human aldo-keto reductase AKR1C1 reduces the α,β-unsaturated aldehyde 4-hydroacy-2-nonenal to 1,4-dihydroxy-2-nonene
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DOI：
10.1074/jbc.m006655200
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发表时间：
2001-01-26
影响因子：
4.8
通讯作者：
Penning, TM
中科院分区：
文献类型：
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作者：
Burczynski, ME;Sridhar, GR;Penning, TM
人的醛酮还原酶AKR1C1(20α(3α)-羟基类固醇脱氢酶)是由亲电的Michael受体和通过假定的抗氧化反应元件(Burczynski，M.E.，Lin，H.K.，和Penning，T.M.(1999)癌症研究报告59,607-614)诱导的。生理上，AKR1C1通过将激素转化为非活性代谢产物20α-羟基孕酮来调节孕酮的作用，在毒理学上，该酶将多环芳烃反式二氢二醇激活为氧化还原循环邻苯二酚，然而，其被Michael受体和氧化应激有效诱导的意义尚不清楚。AKR1C1能高效还原脂质过氧化过程中产生的4-羟基-8-壬烯醛(HNE)等α，β-不饱和醛。动力学研究表明，AKR1C1可还原HNE(K-m=34um，k(Cat)=8.8min(-1))，其k(Cat)/K-m与20个α-羟基类固醇相似。另外6个同源重组AKR被检测其降低HNE的能力。其中，AKR1C1具有最高的比活性之一，也是唯一由氧化应激和耗尽谷胱甘肽(乙氰酸)的试剂诱导的异构体。AKR1C亚家族的几种羟基类固醇脱氢酶比醛还原酶(AKR1A1)具有更高的活性。核磁共振波谱分析表明，HNE的NADPH还原产物为1，4-二羟基-2-壬烯。重组烟酰胺辅因子AKR1c1的K-m值(K-m NADPH类似于6微米，K-m(APP)NADH和GT；6 mm)表明它适合于HNE的还原代谢。同型异构体逆转录聚合酶链式反应显示，HNE暴露于HeppG2细胞后，AKR1C1mRNA水平升高。因此，HNE通过AKR1C1诱导自己的新陈代谢，这种酶可能在对抗氧化应激的反应中发挥迄今未被认识的作用。AKRs代表了GSH非依赖/NADPH依赖的还原消除HNE的替代途径。其中，AKR1C1为ROS暴露后的HNE提供了一种可诱导的胞质屏障。
The human aldo-keto reductase AKR1C1 (20 alpha (3 alpha)-hydroxysteroid dehydrogenase) is induced by electrophilic Michael accepters and reactive oxygen species (ROS) via a presumptive antioxidant response element (Burczynski, M. E., Lin, H. K., and Penning, T. M. (1999) Cancer Res. 59, 607-614). Physiologically, AKR1C1 regulates progesterone action by converting the hormone into its inactive metabolite 20 alpha -hydroxyprogesterone, and toxicologically this enzyme activates polycyclic aromatic hydrocarbon trans-dihydrodiols to redox-cycling o-quinones, However, the significance of its potent induction by Michael accepters and oxidative stress is unknown. 4-Hydroxy-8-nonenal (HNE) and other alpha,beta -unsaturated aldehydes produced during lipid peroxidation were reduced by AKR1C1 with high catalytic efficiency. Kinetic studies revealed that AKR1C1 reduced HNE (K-m = 34 muM, k(cat) = 8.8 min(-1)) with a k(cat)/K-m similar to that for 20 alpha -hydroxysteroids. Six other homogeneous recombinant AKRs were examined for their ability to reduce HNE. Of these, AKR1C1 possessed one of the highest specific activities and was the only isoform induced by oxidative stress and by agents that deplete glutathione (ethacrynic acid). Several hydroxysteroid dehydrogenases of the AKR1C subfamily catalyzed the reduction of HNE with higher activity than aldehyde reductase (AKR1A1). NMR spectroscopy identified the product of the NADPH-dependent reduction of HNE as 1,4-dihydroxy-2-nonene. The K-m of recombinant AKR1C1 for nicotinamide cofactors (K-m NADPH similar to6 muM, K-m(app) NADH >6 mM) suggested that it is primed for reductive metabolism of HNE. Isoformspecific reverse transcription-polymerase chain reaction showed that exposure of HeppG2 cells to HNE resulted in elevated levels of AKR1C1 mRNA. Thus, HNE induces its own metabolism via AKR1C1, and this enzyme may play a hitherto unrecognized role in a response mounted to counter oxidative stress. AKRs represent alternative GSH-independent/NADPH-dependent routes for the reductive elimination of HNE. Of these, AKR1C1 provides an inducible cytosolic barrier to HNE following ROS exposure.