Differential modulation by exogenous carbon monoxide of TNF-alpha stimulated mitogen-activated protein kinases in rat pulmonary artery endothelial cells.
Heme oxygenase-1 (HO-1) is an enzyme that is highly inducible by various cellular stressors, especially oxidant injury. Our laboratory and others have demonstrated that induction of HO-1 exerts an antiinflammatory effect both in vitro and in vivo. We hypothesized that carbon monoxide (CO), a major catalytic byproduct of heme catalysis by HO-1, may mediate this antiinflammatory effect by modulating signal transduction pathways, in particular the mitogen-activated protein (MAP) kinase pathway. Confluent primary cultures of rat pulmonary artery endothelial cells (RPAEC) were treated with tumor necrosis factor-alpha (TNF-alpha; 50 ng/ml), and whole-cell extracts were assayed for phosphorylated ERK1/2, JNK1/2, and p38 MAP kinases. These three major MAP kinase pathways were activated by TNF-alpha in a time-dependent manner. RPAEC treated with TNF-alpha in the presence of a low concentration of CO (1%) exhibited marked attenuation of the phosphorylation of ERK1/2 MAP kinase when compared with cells treated with TNF-alpha alone. A similar effect was seen on the upstream MEK 1/2 kinase. Interestingly, CO (1%) accentuated TNF-alpha-induced phosphorylated p38 MAP kinase. These effects of exogenous CO on the ERK1/2 and p38 systems could be replicated by overexpression of HO-1 in RPAEC, using an adenoviral vector. As these MAP kinases are implicated in the regulation of various inflammatory molecules and adhesion molecules, our data provide a potential mechanism by which HO-1, acting via CO, may modulate the inflammatory response by differential activation of the MAP kinase pathway.
Sethi
Jigme M
JM
Department of Medicine, Section of Pulmonary and Critical Care Medicine, Yale University School of Medicine, New Haven, CT, USA.
Otterbein
Leo E
LE
Choi
Augustine M K
AM
D000818:Animals; D002248:Carbon Monoxide / Q000494:pharmacology*; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000201:enzymology*; D006419:Heme Oxygenase (Decyclizing) / Q000235:genetics / Q000378:metabolism; D051547:Heme Oxygenase-1; D007700:Kinetics; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000187:drug effects / Q000378:metabolism*; D010766:Phosphorylation; D011651:Pulmonary Artery; D051381:Rats; D011994:Recombinant Proteins / Q000378:metabolism; D013997:Time Factors; D014162:Transfection; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
D011994:Recombinant Proteins; D014409:Tumor Necrosis Factor-alpha; D002248:Carbon Monoxide; D006419:Heme Oxygenase (Decyclizing); D051547:Heme Oxygenase-1; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases