Thioredoxin 1 downregulates MCP-1 secretion and expression in human endothelial cells by suppressing nuclear translocation of activator protein 1 and redox factor-1.
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.
Chen
Beidong
B
Institute of Biophysics, Chinese Academy of Sciences, Beijing Normal University, Beijing, China.
Guan
Dandan
D
Cui
Zong Jie
ZJ
Wang
Xian
X
Shen
Xun
X
D021581:Active Transport, Cell Nucleus; D018932:Chemokine CCL2 / Q000235:genetics / Q000378:metabolism*; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase / Q000235:genetics / Q000378:metabolism*; D042783:Endothelial Cells / Q000378:metabolism*; D017353:Gene Deletion; D005786:Gene Expression Regulation / Q000502:physiology; D006801:Humans; D017382:Reactive Oxygen Species; D013879:Thioredoxins / Q000378:metabolism*; D018808:Transcription Factor AP-1 / Q000235:genetics / Q000378:metabolism*
C111835:CCL2 protein, human; D018932:Chemokine CCL2; D017382:Reactive Oxygen Species; D018808:Transcription Factor AP-1; D013879:Thioredoxins; C085108:APEX1 protein, human; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase