Institute of Biophysics, Chinese Academy of Sciences, Beijing Normal University, Beijing, China.
Am J Physiol Cell Physiol. 2010 May;298(5):C1170-9. doi: 10.1152/ajpcell.00223.2009. Epub 2009 Dec 30.
To know whether thioredoxin 1 (Trx1) works for an antioxidant defense mechanism in atherosclerosis, the effect of Trx1 on the release of monocyte chemoattractant protein-1 (MCP-1), a potent chemoattractant for recruitment and accumulation of monocytes/macrophages in the intima of artery vessel, was investigated in human endothelial-like EA.hy 926 cells. It was found that overexpression of Trx1 suppressed, whereas knockdown of endogenous Trx1 enhanced, oxidized low-density lipoprotein (oxLDL)-stimulated MCP-1 release and expression in the cells. It was also observed that overexpression of Trx1 suppressed, whereas depletion of endogenous Trx1 greatly promoted, nuclear translocation of c-Jun and the redox factor-1 (Ref-1). Electrophoretic mobility shift assay showed significantly reduced DNA-binding activity of activator protein-1 (AP-1) in Trx1-overexpressing cells but apparently enhanced DNA binding activity of AP-1 in Trx1-knockdown cells, indicating that nuclear Ref-1 rather than Trx1 itself finally dominates the regulation of AP-1 activity, although Trx1 is considered to upregulate AP-1 activity. It was also observed that Trx1 depressed intracellular generation of reactive oxygen species (ROS). Diphenyleneiodonium (DPI), the inhibitor of NADPH oxidase, suppressed MCP-1 secretion, whereas transient expression of Nox1 enhanced transcription of MCP-1 in endothelial cells. Assays with AP-1 and MCP-1 luciferase reporters further demonstrated that transient expression of Trx1 significantly depressed the transcriptional activity of c-Jun/c-Fos and consequent MCP-1 transcription. This study suggests that Trx1 inherently suppresses MCP-1 expression in vascular endothelium and may prevent atherosclerosis by depressing MCP-1 release. Besides the suppression of intracellular ROS generation, the inhibition of nuclear translocation of AP-1 and Ref-1 are mainly responsible for the downregulation of MCP-1 by Trx1.
为了探究硫氧还蛋白 1（Trx1）是否在动脉粥样硬化的抗氧化防御机制中发挥作用，研究人员在人内皮样 EA.hy 926 细胞中研究了 Trx1 对单核细胞趋化蛋白-1（MCP-1）释放的影响，MCP-1 是一种强有力的趋化因子，可招募和积累单核细胞/巨噬细胞到动脉血管内膜中。结果发现，过表达 Trx1 可抑制氧化型低密度脂蛋白（oxLDL）刺激的 MCP-1 释放和表达，而敲低内源性 Trx1 则增强了这一过程。研究还观察到，过表达 Trx1 可抑制 c-Jun 和氧化还原因子-1（Ref-1）的核易位，而耗尽内源性 Trx1 则大大促进了这一过程。电泳迁移率变动分析显示，在 Trx1 过表达细胞中，激活蛋白-1（AP-1）的 DNA 结合活性显著降低，而在 Trx1 敲低细胞中，AP-1 的 DNA 结合活性明显增强，表明核 Ref-1 最终支配着 AP-1 活性的调节，尽管 Trx1 被认为可上调 AP-1 活性。研究还观察到，Trx1 可抑制细胞内活性氧（ROS）的产生。NADPH 氧化酶抑制剂二苯基碘（DPI）可抑制 MCP-1 的分泌，而瞬时表达 Nox1 可增强内皮细胞中 MCP-1 的转录。用 AP-1 和 MCP-1 荧光素酶报告基因进行的检测进一步表明，瞬时表达 Trx1 可显著抑制 c-Jun/c-Fos 的转录活性及其随后的 MCP-1 转录。本研究表明，Trx1 内在地抑制血管内皮细胞中 MCP-1 的表达，并可能通过抑制 MCP-1 的释放来预防动脉粥样硬化。除了抑制细胞内 ROS 的产生外，AP-1 和 Ref-1 的核易位抑制主要负责 Trx1 下调 MCP-1。
