title: Inducible nitric oxide synthase gene deletion exaggerates MAPK-mediated cyclooxygenase-2 induction by inflammatory stimuli.
abstract: Cyclooxygenase (COX)-2 and inducible nitric oxide (NO) synthase (iNOS) are responsive to a wide array of inflammatory stimuli, have been localized to vascular smooth muscle cells (SMCs), and are intimately linked to the progression of vascular disease, including atherosclerotic lesion formation. We and others have shown that the production and subsequent impact of COX products appear to be correlative with the status of NO synthesis. This study examined the impact of inflammation-driven NO production on COX-2 expression in SMCs. Concurrent stimulation of quiescent rat aortic SMCs with lipopolysaccharide (LPS) and interferon (IFN)-gamma increased COX-2, iNOS, and nitrite production. Pharmacological inhibition of NO synthase (N(G)-monomethyl-l-arginine) concentration- and time-dependently magnified LPS + IFN-gamma-mediated COX-2 mRNA and protein induction in a cGMP-independent manner. COX-2 induction was associated with activation of the ERK, p38, and JNK mitogen-activated protein kinase (MAPK) pathways. Interestingly, NO synthase inhibition enhanced ERK, p38, and to a lesser extent JNK phosphorylation but suppressed MAPK phosphatase (MKP)-1 induction in response to LPS + IFN-gamma. Similarly, the exposure of SMCs from iNOS(-/-) mice to LPS + IFN-gamma produced an enhancement of COX-2 induction, p38, and JNK phosphorylation and an attenuated upregulation of MKP-1 versus their wild-type counterparts. Taken together, our data indicate that NO, in part derived from iNOS, negatively regulates the immediate early induction of COX-2 in response to inflammatory stimuli.
authors.affiliation: Department of Pathology and Laboratory Medicine, Center of Vascular Biology, Weill Cornell Medical College of CornellUniversity, New York, New York 10065, USA. bdl2001@med.cornell.edu
authors.forename: Brian D
authors.initials: BD
authors.lastname: Lamon
authors.forename: Rita K
authors.initials: RK
authors.lastname: Upmacis
authors.forename: Ruba S
authors.initials: RS
authors.lastname: Deeb
authors.forename: Hilal
authors.initials: H
authors.lastname: Koyuncu
authors.forename: David P
authors.initials: DP
authors.lastname: Hajjar
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001011:Aorta / Q000378:metabolism*; D015153:Blotting, Western; D002478:Cells, Cultured; D051546:Cyclooxygenase 2 / Q000378:metabolism*; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism; D007249:Inflammation / Q000378:metabolism*; D007371:Interferon-gamma / Q000494:pharmacology; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism; D008070:Lipopolysaccharides / Q000494:pharmacology; D051379:Mice; D018345:Mice, Knockout; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000378:metabolism*; D032389:Myocytes, Smooth Muscle / Q000166:cytology / Q000378:metabolism*; D052247:Nitric Oxide Synthase Type II / Q000235:genetics* / Q000378:metabolism; D010766:Phosphorylation; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors
chemical_list: D008070:Lipopolysaccharides; D007371:Interferon-gamma; D052247:Nitric Oxide Synthase Type II; D051546:Cyclooxygenase 2; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases