Brigelius-Flohé R, Friedrichs B, Maurer S, Schultz M, Streicher R
German Institute of Human Nutrition, Potsdam-Rehbrücke, Germany.
Biochem J. 1997 Nov 15;328 ( Pt 1)(Pt 1):199-203. doi: 10.1042/bj3280199.
Oxygen radicals are commonly accepted mediators in the tumour necrosis factor-mediated nuclear factor kappa B (NF kappa B) signalling cascade, but evidence for their role during interleukin-1 (IL-1) signalling is lacking. To test the involvement of hydroperoxides we investigated whether IL-1-induced NF kappa B activation could be influenced by glutathione peroxidases (GPx). These enzymes remove hydroperoxides with various specificities for the hydroperoxide substrate. By overexpressing phospholipid hydroperoxide glutathione peroxidase (PHGPx), which characteristically reacts with lipophilic hydroperoxides, the roles of H2O2 and lipid hydroperoxides were assessed. A human umbilical endothelial cell line, ECV 304, was stably transfected with the genes for both PHGPx and selenophosphate synthetase (selD), which provides selenophosphate for selenoprotein biosynthesis. When grown in selenium-deficient culture medium, the double-transfected clone (ECVPHGPx+SelD+) expressed 5-fold higher (P<0.005) PHGPx activity (measured by phosphatidylcholine hydroperoxide removal) than controls. The rate of H2O2 removal was also significantly (P<0.01) higher in this clone. When grown with high levels of extracellular selenium (up to 100 nM selenite), PHGPx activity and H2O2 removal were enhanced substantially in control cells and transfected cells. Under these conditions, PHGPx activity was 1.7-fold (P<0.005) higher in ECVPHGPx+SelD+, but H2O2 removal was the same as in controls. IL-1-induced NF kappa B activation was inhibited by selenium supplementation in control cells. In ECVPHGPx+SelD+ under conditions of selenium restriction, IL-1 induced NF kappa B activation only to a similar extent as under conditions of selenium supplementation in controls, and activation was abolished with 50 nM sodium selenite. These results show that overexpressed PHGPx is sufficient to inhibit NF kappa B activation, and suggests that NF kappa B activation by IL-1 is mediated by a preferential substrate of PHGPx, such as a fatty acid hydroperoxide, rather than by H2O2, the preferred substrate of the more abundant cytosolic GPx.
氧自由基是肿瘤坏死因子介导的核因子κB（NFκB）信号级联反应中普遍公认的介质，但在白细胞介素-1（IL-1）信号传导过程中其作用的证据尚缺乏。为了检测氢过氧化物的参与情况，我们研究了IL-1诱导的NFκB激活是否会受到谷胱甘肽过氧化物酶（GPx）的影响。这些酶对氢过氧化物底物具有不同的特异性来清除氢过氧化物。通过过表达磷脂氢过氧化物谷胱甘肽过氧化物酶（PHGPx），其特异性地与亲脂性氢过氧化物反应，来评估H2O2和脂质氢过氧化物的作用。人脐静脉内皮细胞系ECV 304用PHGPx和硒磷酸合成酶（selD）的基因进行稳定转染，selD为硒蛋白生物合成提供硒磷酸。当在缺硒培养基中生长时，双转染克隆（ECVPHGPx + SelD +）的PHGPx活性（通过去除磷脂酰胆碱氢过氧化物来测量）比对照高5倍（P < 0.005）。该克隆中H2O2的清除率也显著更高（P < 0.01）。当在高水平的细胞外硒（高达100 nM亚硒酸盐）中生长时，对照细胞和转染细胞中的PHGPx活性和H2O2清除率均显著提高。在这些条件下，ECVPHGPx + SelD +中的PHGPx活性高1.7倍（P < 0.005），但H2O2清除率与对照相同。对照细胞中补充硒可抑制IL-1诱导的NFκB激活。在缺硒条件下的ECVPHGPx + SelD +中，IL-1诱导的NFκB激活仅达到与对照中补硒条件下相似的程度，并且用50 nM亚硒酸钠可消除激活。这些结果表明，过表达的PHGPx足以抑制NFκB激活，并表明IL-1介导的NFκB激活是由PHGPx的优先底物（如脂肪酸氢过氧化物）介导的，而不是由更丰富的胞质GPx的优先底物H2O2介导的。
