Banning Antje, Schnurr Kerstin, Böl Gaby Fleur, Kupper Dagmar, Müller-Schmehl Katrin, Viita Helena, Ylä-Herttuala Seppo, Brigelius-Flohé Regina
Department of Vitamins and Atherosclerosis, German Institute of Human Nutrition, Potsdam-Rehbrücke, Germany.
Free Radic Biol Med. 2004 Jan 15;36(2):135-44. doi: 10.1016/j.freeradbiomed.2003.10.027.
Cytokines or hydroperoxides upregulate cell adhesion molecules (CAM) in early stages of atherosclerosis. VCAM-1 expression was therefore investigated in rabbit aortic smooth muscle cells (SMC) stably transfected either with phospholipid hydroperoxide glutathione peroxidase (PHGPx; SMCPHGPx) as a hydroperoxide-reducing enzyme or with 15-lipoxygenase (15-LOX; SMCLOX) as a hydroperoxide-producing enzyme. Transfected cells showed up to 3-fold enhanced PHGPx and a marked LOX activity, respectively, that was absent in controls. Intracellular hydroperoxides were 6-fold higher in SMCLOX than in SMC or SMCPHGPx. Intracellular protein thiols were decreased by 50 and 90% in SMCPHGPx and SMCLOX, respectively. Glutathione mixed disulfides were tentatively increased from SMC via SMCPHGPx to SMCLOX, accordingly. Thiol reduction with tris(2-carboxyethyl)phosphine completely restored protein thiols in SMCPHGPx, whereas in SMCLOX only 60% of control values were recovered. Basal VCAM-1 mRNA levels were decreased by 50% in SMCPHGPx and 75% in SMCLOX. VCAM-1-inducibility was abrogated in SMCLOX but not in SMCPHGPx. Accordingly, NFkappaB-driven reporter gene activation by IL-1 was unaffected in SMCPHGPx but abolished in SMCLOX. The data confirm that PHGPx overexpression dampens CAM expression either by lowering stimulatory hydroperoxides or by using hydroperoxides for protein modification. But hydroperoxides, when constitutively overproduced as in SMCLOX, inhibit CAM expression and render cells refractory to IL-1 stimulation likely due to oxidation of protein thiols of the signaling system.
细胞因子或氢过氧化物在动脉粥样硬化早期会上调细胞黏附分子（CAM）。因此，研究了磷脂氢过氧化物谷胱甘肽过氧化物酶（PHGPx；SMCPHGPx）作为一种氢过氧化物还原酶或15-脂氧合酶（15-LOX；SMCLOX）作为一种氢过氧化物生成酶稳定转染的兔主动脉平滑肌细胞（SMC）中VCAM-1的表达。转染细胞分别显示出高达3倍的PHGPx增强和显著的LOX活性，而对照细胞中则没有。SMCLOX中的细胞内氢过氧化物比SMC或SMCPHGPx高6倍。SMCPHGPx和SMCLOX中的细胞内蛋白质硫醇分别减少了50%和90%。相应地，谷胱甘肽混合二硫化物从SMC经SMCPHGPx到SMCLOX呈逐渐增加趋势。用三（2-羧乙基）膦进行硫醇还原可使SMCPHGPx中的蛋白质硫醇完全恢复，而在SMCLOX中仅恢复到对照值的60%。基础VCAM-1 mRNA水平在SMCPHGPx中降低了50%，在SMCLOX中降低了75%。SMCLOX中VCAM-1的诱导性被消除，但SMCPHGPx中未被消除。相应地，IL-1对NFκB驱动的报告基因激活在SMCPHGPx中未受影响，但在SMCLOX中被消除。数据证实，PHGPx的过表达通过降低刺激性氢过氧化物或利用氢过氧化物进行蛋白质修饰来抑制CAM表达。但是，当像在SMCLOX中那样组成性地过度产生氢过氧化物时，会抑制CAM表达，并使细胞对IL-1刺激产生抗性，这可能是由于信号系统蛋白质硫醇的氧化所致。
