Inhibition of endothelial vascular cell adhesion molecule-1 expression by nitric oxide involves the induction and nuclear translocation of IkappaBalpha.
The induction of vascular cell adhesion molecule-1 (VCAM-1) expression by tumor necrosis factor (TNF)-alpha requires the activation of nuclear factor-kappaB (NF-kappaB) via a process involving the phosphorylation and degradation of its cytoplasmic inhibitor, IkappaBalpha. We have shown that nitric oxide (NO) decreases VCAM-1 expression via inhibition of NF-kappaB activation. To determine how NO inhibits NF-kappaB, we studied the fate of IkappaBalpha following TNF-alpha stimulation in the presence of NO donors S-nitrosoglutathione and sodium nitroprusside. Activation of NF-kappaB by TNF-alpha occurred within 15 min and coincided with rapid degradation of IkappaBalpha. Co-treatment with NO donors did not prevent IkappaBalpha phosphorylation or degradation. However, after 2 h of TNF-alpha stimulation, NO donors inhibited NF-kappaB activation and augmented IkappaBalpha resynthesis and nuclear translocation by 2.5- and 3-fold, respectively. This correlated with a 75% reduction in TNF-alpha-induced VCAM-1 expression. In a time-dependent manner, NO donors alone caused the nuclear translocation of IkappaBalpha. To confirm that NO donors have similar effects as endogenously derived NO, murine macrophage-like cells, RAW264.7, were co-cultured with endothelial cells. Induction of RAW264.7-derived NO inhibited lipopolysaccharide-induced endothelial VCAM-1 expression, which was reversed by the NO synthase inhibitor Nomega-monomethyl-L-arginine. These findings indicate that NO inhibits NF-kappaB activation and VCAM-1 expression by increasing the expression and nuclear translocation of IkappaBalpha.
Spiecker
M
M
Vascular Medicine and Atherosclerosis Unit, Cardiovascular Division, Brigham & Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA.
Peng
H B
HB
Liao
J K
JK
D001692:Biological Transport; D002478:Cells, Cultured; D018920:Coculture Techniques; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004730:Endothelium, Vascular / Q000187:drug effects; D005978:Glutathione / Q000031:analogs & derivatives / Q000494:pharmacology; D006801:Humans; D020672:I-kappa B Proteins; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000037:antagonists & inhibitors* / Q000378:metabolism; D009569:Nitric Oxide / Q000494:pharmacology*; D009603:Nitroso Compounds / Q000494:pharmacology; D010766:Phosphorylation; D026422:S-Nitrosoglutathione; D051996:Transcription Factor RelA; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D019010:Vascular Cell Adhesion Molecule-1 / Q000096:biosynthesis*
D004268:DNA-Binding Proteins; D020672:I-kappa B Proteins; D016328:NF-kappa B; C000606204:NFKBIA protein, human; D009603:Nitroso Compounds; D051996:Transcription Factor RelA; D014409:Tumor Necrosis Factor-alpha; D019010:Vascular Cell Adhesion Molecule-1; D000072000:NF-KappaB Inhibitor alpha; D009569:Nitric Oxide; D026422:S-Nitrosoglutathione; D005978:Glutathione