Levrand Sandra, Pesse Benoît, Feihl François, Waeber Bernard, Pacher Pal, Rolli Joëlle, Schaller Marie-Denise, Liaudet Lucas
Division of Critical Care, Division of Clinical Pathophysiology, Department of Internal Medicine, University Hospital, 1011 Lausanne, Switzerland.
J Biol Chem. 2005 Oct 14;280(41):34878-87. doi: 10.1074/jbc.M501977200. Epub 2005 Aug 3.
Peroxynitrite is a potent oxidant and nitrating species proposed as a direct effector of myocardial damage in numerous cardiac pathologies. Whether peroxynitrite also acts indirectly, by modulating cell signal transduction in the myocardium, has not been investigated. Therefore, we examined a possible role for peroxynitrite on the activation of NF-kappaB, a crucial pro-inflammatory transcription factor, in cultured H9C2 cardiomyocytes. H9C2 cells were stimulated with tumor necrosis factor-alpha or lipopolysaccharide following a brief (20-min) exposure to peroxynitrite. NF-kappaB activation (phosphorylation and degradation of its inhibitor IkappaBalpha, nuclear translocation of NF-kappaB p65, and NF-kappaB DNA binding) triggered by lipopolysaccharide or tumor necrosis factor-alpha was abrogated by peroxynitrite. Peroxynitrite also inhibited NF-kappaB in two human endothelial cell lines activated with tumor necrosis factor-alpha or interleukin-1beta. These effects were related to oxidative but not nitrative chemistry and were still being observed while nitration was suppressed by epicatechin. The mechanism of NF-kappaB inhibition by peroxynitrite was a complete blockade of phosphorylation and activation of the upstream kinase IkappaB kinase (IKK) beta, required for canonical, pro-inflammatory NF-kappaB activation. At the same time, peroxynitrite activated phosphorylation of NF-kappaB-inducing kinase and IKKalpha, considered as part of an alternative, noncanonical NF-kappaB activation pathway. Suppression of IKKbeta-dependent NF-kappaB activation translated into a marked inhibition of the transcription of NF-kappaB-dependent genes by peroxynitrite. Thus, peroxynitrite has a dual effect on NF-kappaB, inhibiting canonical IKKbeta-dependent NF-kappaB activation while activating NF-kappaB-inducing kinase and IKKalpha phosphorylation, which suggests its involvement in an alternative pathway of NF-kappaB activation. These findings offer new perspectives for the understanding of the relationships between redox stress and inflammation.
过氧亚硝酸盐是一种强效氧化剂和硝化物质，在众多心脏疾病中被认为是心肌损伤的直接效应物。过氧亚硝酸盐是否也通过调节心肌细胞信号转导间接发挥作用，尚未得到研究。因此，我们研究了过氧亚硝酸盐在培养的H9C2心肌细胞中对关键促炎转录因子NF-κB激活的可能作用。在短暂（20分钟）暴露于过氧亚硝酸盐后，用肿瘤坏死因子-α或脂多糖刺激H9C2细胞。过氧亚硝酸盐消除了脂多糖或肿瘤坏死因子-α引发的NF-κB激活（其抑制剂IκBα的磷酸化和降解、NF-κB p65的核转位以及NF-κB与DNA的结合）。过氧亚硝酸盐还抑制了用肿瘤坏死因子-α或白细胞介素-1β激活的两个人内皮细胞系中的NF-κB。这些作用与氧化而非硝化化学有关，并且在表儿茶素抑制硝化作用时仍可观察到。过氧亚硝酸盐抑制NF-κB的机制是完全阻断经典促炎NF-κB激活所需的上游激酶IκB激酶（IKK）β的磷酸化和激活。同时，过氧亚硝酸盐激活了NF-κB诱导激酶和IKKα的磷酸化，它们被认为是替代的非经典NF-κB激活途径的一部分。IKKβ依赖性NF-κB激活的抑制转化为过氧亚硝酸盐对NF-κB依赖性基因转录的显著抑制。因此，过氧亚硝酸盐对NF-κB有双重作用，抑制经典的IKKβ依赖性NF-κB激活，同时激活NF-κB诱导激酶和IKKα磷酸化，这表明其参与了NF-κB激活的替代途径。这些发现为理解氧化还原应激与炎症之间的关系提供了新的视角。
