Zinc finger transcription factors as molecular targets for nitric oxide-mediated immunosuppression:: Inhibition of IL-2 gene expression in murine lymphocytes
Zinc finger transcription factors as molecular targets for nitric oxide-mediated immunosuppression:: Inhibition of IL-2 gene expression in murine lymphocytes
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DOI：
10.1007/bf03402096
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发表时间：
1999-11-01
影响因子：
5.7
通讯作者：
Kröncke, KD
中科院分区：
文献类型：
--
作者：
Berendji, D;Kolb-Bachofen, V;Kröncke, KD
背景：一氧化氮(NO)经常被证明具有免疫抑制活性。材料和方法：用生理刺激IL-1β激活小鼠T细胞淋巴瘤EL4-6.1细胞，在亚毒性浓度的生理自发NO供体S-亚硝基半胱氨酸(SNOC)存在或不存在的情况下，表达IL-2mRNA。结果：NO可抑制IL-1β诱导的EL4-6.1细胞IL-2mRNA的表达。NO的抑制作用呈浓度依赖性，且是完全可逆的。重要的是，所用浓度的NO既不会诱导细胞凋亡，也不会导致细胞坏死。已知IL-2基因表达的显性调控存在于锌指转录因子Sp1或EGR-1以及非锌指蛋白NFAT中。NO取消重组Sp1和EGR-1的DNA结合活性。更重要的是，凝胶漂移分析也显示，来自未处理核提取液的天然Sp1和来自未处理的活淋巴细胞的天然Sp1缺乏DNA结合。结论：NO对锌指转录因子的失活可能是哺乳动物体内NO免疫抑制活性的分子机制之一，从而参与了生理刺激后NO对IL-2基因表达的抑制。对导致NO介导的、完全可逆的免疫反应抑制的分子机制的准确理解可能导致将这种自然发生的工具用作炎症性疾病的辅助工具。
Background: Nitric oxide (NO) has frequently been shown to display immunosuppressive activities. We describe here a molecular mechanism contributing to this effect.Materials and Methods: Murine T cell lymphoma EL4-6.1 cells were activated with the physiological stimulus interleukin (IL)-1 beta to express IL-2 mRNA in the presence or absence of subtoxic concentrations of the physiological spontaneous NO donor S-nitrosocysteine (SNOC). subsequently, semiquantitative RT-PCR and gel shift assays with nuclear extracts were performed to analyze the effects of NO on IL-2 mRNA expression and on the activity of the dominant regulating transcription factors Sp1, EGR-1, and NFATc.Results: NO inhibits IL-1 beta-induced IL-2 mRNA expression in EL4-6.1 cells. The suppressive activity of NO was concentration dependent and found to be completely reversible. Importantly, NO at the concentrations used induced neither apoptosis nor necrosis. Dominant regulation of IL-2 gene expression is known to reside in the zinc finger transcription factors Sp1 or EGR-1 and in the non-zinc finger protein NFAT. NO abrogates the DNA binding activities of recombinant Sp1 and EGR-1. More importantly, gel shift assays also showed a lack of DNA binding of native Sp1 derived from NO-treated nuclear extracts and that from NO-treated viable lymphocytes. This effect is selective, as the DNA binding activity of recombinant NFATc was not affected by NO.Conclusion: Inactivation of zinc finger transcription factors by NO appears to be a molecular mechanism in the immunosuppressive activity of NO in mammals, thus contributing to NO-mediated inhibition of IL-2 gene expression after physiological stimuli. The exact understanding of the molecular mechanism leading to NO-mediated, fully reversible suppression of immune reactions may lead to use of this naturally occuring tool as an aid in inflammatory diseases.