Department of Pathology, University of Otago, Christchurch, Christchurch, New Zealand.
Antioxid Redox Signal. 2012 Aug 1;17(3):411-21. doi: 10.1089/ars.2011.4348. Epub 2012 Mar 2.
Reactive oxygen species released from neutrophils during vascular inflammation could contribute to endothelial dysfunction seen in diseases such as atherosclerosis. Activated neutrophils generate hydrogen peroxide (H(2)O(2)) and hypochlorous acid (HOCl), as well as chloramines that are formed when HOCl reacts with amino compounds. These oxidants preferentially target thiol groups and thiol-containing proteins. The peroxiredoxins (Prxs) are thiol proteins that have high reactivity with H(2)O(2) and may also be sensitive to HOCl and chloramines.
We have investigated human umbilical vein endothelial cells and shown that their cytoplasmic (Prx1 and Prx2) and mitochondrial (Prx3) Prxs are oxidized when they are exposed to H(2)O(2), HOCl, or cell-permeable chloramines. H(2)O(2) converted the Prxs to hyperoxidized, inactive forms, with little accumulation of disulfide-linked dimers. The oxidized Prxs were reduced over hours, presumably due to the action of endothelial sulfiredoxin. In contrast to the hyperoxidation seen with H(2)O(2), HOCl and the chloramine derivatives of glycine and ammonia converted the Prxs to disulfide-linked dimers and dimerization was reversed within 10-30 min of oxidant removal. HOCl treatment caused thioredoxin reductase (TrxR) inhibition with no reversal of dimerization. The cytotoxicity of ammonia chloramine was increased when cells were pretreated with H(2)O(2) to hyperoxidize the Prxs, or when the chloramine was added in the presence of the TrxR inhibitor, auranofin.
We describe the novel observation that exposure of nucleated cells to inflammatory oxidants results in the accumulation of Prxs in the dimeric form.
Endothelial cell Prxs are sensitive targets for neutrophil-derived oxidants and may protect against their damaging effects.
血管炎症期间中性粒细胞释放的活性氧可能导致动脉粥样硬化等疾病中观察到的内皮功能障碍。活化的中性粒细胞产生过氧化氢 (H2O2) 和次氯酸 (HOCl)，以及当 HOCl 与氨基酸化合物反应时形成的氯胺。这些氧化剂优先靶向巯基基团和含巯基的蛋白质。过氧化物酶 (Prx) 是一种巯基蛋白，对 H2O2 具有高反应性，也可能对 HOCl 和氯胺敏感。
我们研究了人脐静脉内皮细胞，并表明当它们暴露于 H2O2、HOCl 或细胞通透的氯胺时，它们的细胞质 (Prx1 和 Prx2) 和线粒体 (Prx3) Prx 被氧化。H2O2 将 Prx 转化为超氧化、无活性形式，几乎没有二硫键连接的二聚体积累。氧化的 Prx 在数小时内被还原，大概是由于内皮硫氧还蛋白的作用。与 H2O2 引起的超氧化形成对比的是，HOCl 和甘氨酸和氨的氯胺衍生物将 Prx 转化为二硫键连接的二聚体，并且在氧化剂去除后的 10-30 分钟内二聚体化得到逆转。HOCl 处理导致硫氧还蛋白还原酶 (TrxR) 抑制，二聚体化没有逆转。当细胞用 H2O2 预处理以超氧化 Prx 时，或当氯胺在 TrxR 抑制剂金诺芬存在下添加时，氨氯胺的细胞毒性增加。
我们描述了一个新的观察结果，即核细胞暴露于炎症性氧化剂会导致 Prx 积累为二聚体形式。
内皮细胞 Prx 是中性粒细胞衍生的氧化剂的敏感靶标，并可能防止其损伤作用。
