Department of Pathology, University of Vermont College of Medicine, Burlington, VT 05405, USA.
Free Radic Biol Med. 2011 Sep 15;51(6):1249-57. doi: 10.1016/j.freeradbiomed.2011.06.025. Epub 2011 Jun 27.
The transcription factor nuclear factor κB (NF-κB) is a critical regulator of inflammation and immunity and is negatively regulated via S-glutathionylation. The inhibitory effect of S-glutathionylation is overcome by glutaredoxin-1 (Grx1), which under physiological conditions catalyzes deglutathionylation and enhances NF-κB activation. The mechanisms whereby expression of the Glrx1 gene is regulated remain unknown. Here we examined the role of NF-κB in regulating activation of Glrx1. Transgenic mice that express a doxycycline-inducible constitutively active version of inhibitory κB kinase-β (CA-IKKβ) demonstrate elevated expression of Grx1. Transient transfection of CA-IKKβ also resulted in significant induction of Grx1. A 2-kb region of the Glrx1 promoter that contains two putative NF-κB binding sites was activated by CA-IKKβ, RelA/p50, and lipopolysaccharide (LPS). Chromatin immunoprecipitation experiments confirmed binding of RelA to the promoter of Glrx1 in response to LPS. Stimulation of C10 lung epithelial cells with LPS caused transient increases in Grx1 mRNA expression and time-dependent increases in S-glutathionylation of IKKβ. Overexpression of Grx1 decreased S-glutathionylation of IKKβ, prolonged NF-κB activation, and increased levels of proinflammatory mediators. Collectively, this study demonstrates that the Glrx1 gene is positively regulated by NF-κB and suggests a feed-forward mechanism to promote NF-κB signaling by decreasing S-glutathionylation.
转录因子核因子 κB（NF-κB）是炎症和免疫的关键调节剂，可通过 S-谷胱甘肽化进行负调控。谷氧还蛋白-1（Grx1）可克服 S-谷胱甘肽化的抑制作用，在生理条件下，Grx1 催化去谷胱甘肽化并增强 NF-κB 的激活。Grx1 基因表达的调控机制尚不清楚。在这里，我们研究了 NF-κB 在调节 Grx1 激活中的作用。表达强力霉素诱导的组成型活性抑制性 κB 激酶-β（CA-IKKβ）的转基因小鼠表现出 Grx1 的高表达。瞬时转染 CA-IKKβ 也导致 Grx1 的显著诱导。Grx1 启动子的 2kb 区域包含两个假定的 NF-κB 结合位点，CA-IKKβ、RelA/p50 和脂多糖（LPS）可激活该区域。染色质免疫沉淀实验证实，LPS 刺激后，RelA 与 Grx1 启动子结合。用 LPS 刺激 C10 肺上皮细胞会导致 Grx1 mRNA 表达的短暂增加和 IKKβ 的 S-谷胱甘肽化的时间依赖性增加。Grx1 的过表达降低了 IKKβ 的 S-谷胱甘肽化，延长了 NF-κB 的激活，并增加了促炎介质的水平。总之，这项研究表明 Grx1 基因受 NF-κB 的正向调节，并提出了一种通过减少 S-谷胱甘肽化来促进 NF-κB 信号转导的正反馈机制。
