Functional role of NF-κB in expression of human endothelial nitric oxide synthase

The transcription factor NE-kappa B has an essential role in inflammation in endothelial cells. Endothelial nitric oxide synthase (eNOS)-derived nitric oxide (NO) prevents vascular inflammation. However, the molecular mechanism underlying NE-kappa B-mediated regulation of eNOS expression has not been clearly elucidated. We here found that NE-KB-activating stimuli, such as lipopolysaccharide, tumor necrosis factor-alpha (TNF-alpha), and interleulcin-1 beta, suppressed eNOS mRNA and protein levels by decreasing mRNA stability, without affecting promoter activity. TNF-alpha-mediated suppression of eNOS expression, mRNA stability, and 3 '-untranslated region (3 ' UTR) activity were inhibited by NE-kappa B inhibitors and Dicer knockdown, but not by p38 MAPK and MEK inhibitors, suggesting the involvement of NE-kappa B-responsive miRNAs in eNOS expression. Moreover, TNF-a increased MIR155HG expression and promoter activity as well as miR-155 biogenesis, and these increases were blocked by NE-kappa B inhibitors. Transfection with antagomiR-155 blocked INF-alpha-mediated suppression of eNOS 3 ' UTR activity, eNOS mRNA and protein levels, and NO and cGMP production. These data provide evidence that NF-kappa B is a negative regulator of eNOS expression via upregulation of miR-155 under inflammatory conditions. These results suggest that NE-kappa B is a potential therapeutic target for preventing vascular inflammation and endothelial dysfunction induced by suppression of miR-155-mediated eNOS expression. (C) 2014 Elsevier Inc. All rights reserved.