Ayad O, Stark J M, Fiedler M M, Menendez I Y, Ryan M A, Wong H R
Division of Critical Care Medicine, Children's Hospital Medical Center, Cincinnati, OH 45229, USA.
J Immunol. 1998 Sep 1;161(5):2594-9.
The chemokine RANTES is thought to be involved in the pathophysiology of inflammation-associated acute lung injury. Although much is known regarding signals that induce RANTES gene expression, relatively few data exist regarding signals that inhibit RANTES gene expression. The heat shock response, a highly conserved cellular defense mechanism, has been demonstrated to inhibit a variety of lung proinflammatory responses. We tested the hypothesis that induction of the heat shock response inhibits RANTES gene expression. Treatment of A549 cells with TNF-alpha induced RANTES gene expression in a concentration-dependent manner. Induction of the heat shock response inhibited subsequent TNF-alpha-mediated RANTES mRNA expression and secretion of immunoreactive RANTES. Transient transfection assays involving a RANTES promoter-luciferase reporter plasmid demonstrated that the heat shock response inhibited TNF-alpha-mediated activation of the RANTES promoter. Inhibition of NF-kappaB nuclear translocation with isohelenin inhibited TNF-alpha-mediated RANTES mRNA expression, indicating that RANTES gene expression is NF-kappaB dependent in A549 cells. Induction of the heat shock response inhibited degradation of the NF-kappaB inhibitory protein, I-kappaBalpha but did not significantly inhibit phosphorylation of I-kappaBalpha. We conclude that the heat shock response inhibits RANTES gene expression by a mechanism involving inhibition of NF-kappaB nuclear translocation and subsequent inhibition of RANTES promoter activation. The mechanism by which the heat shock response inhibits NF-kappaB nuclear translocation involves stabilization of I-kappaBalpha, without significantly affecting phosphorylation of I-kappaBalpha.
趋化因子调节激活正常T细胞表达和分泌的因子（RANTES）被认为参与了炎症相关急性肺损伤的病理生理学过程。尽管关于诱导RANTES基因表达的信号已了解很多，但关于抑制RANTES基因表达的信号的数据相对较少。热休克反应是一种高度保守的细胞防御机制，已被证明可抑制多种肺部促炎反应。我们测试了热休克反应的诱导抑制RANTES基因表达这一假说。用肿瘤坏死因子-α（TNF-α）处理A549细胞以浓度依赖的方式诱导RANTES基因表达。热休克反应的诱导抑制了随后TNF-α介导的RANTES mRNA表达和免疫反应性RANTES的分泌。涉及RANTES启动子-荧光素酶报告质粒的瞬时转染实验表明，热休克反应抑制了TNF-α介导的RANTES启动子激活。用异戊烯醇抑制核因子-κB（NF-κB）核转位可抑制TNF-α介导的RANTES mRNA表达，表明在A549细胞中RANTES基因表达是NF-κB依赖性的。热休克反应的诱导抑制了NF-κB抑制蛋白I-κBα的降解，但并未显著抑制I-κBα的磷酸化。我们得出结论，热休克反应通过一种涉及抑制NF-κB核转位以及随后抑制RANTES启动子激活的机制来抑制RANTES基因表达。热休克反应抑制NF-κB核转位的机制涉及I-κBα的稳定，而不显著影响I-κBα的磷酸化。
