Nitric oxide sustains nuclear factor kappaB activation in cytokine-stimulated chondrocytes.
OBJECTIVE
In the current studies we have examined the effects of nitric oxide, and its redox derivatives peroxynitrite and S-nitrosothiol, S-nitrosocysteine, on nuclear factor kappaB (NF-kappaB) activation in cytokine-stimulated bovine chondrocytes.


METHODS
The kinetics of NF-kappaB activation (p65 nuclear translocation) were assessed by immunofluorescence and immunoblot assays.


RESULTS
We observed that the two nitric oxide redox species, peroxynitrite and S-nitrosocysteine, exert opposing effects on NF-kappaB activation. However, in lipopolysaccharide (LPS)/cytokine-stimulated chondrocytes (LPS, IL-1beta and TNF-alpha (LIT)) in the presence or absence of the NOS inhibitor L-NG-monomethyl arginine citrate (L-NMMA), the results indicate that nitric oxide causes persistent activation of NF-kappaB, most likely via generation of the free radical derivative peroxynitrite.


CONCLUSIONS
The studies indicate that while nitric oxide is not required for immediate NF-kappaB activation in cytokine-stimulated chondrocytes, its effect is to sustain nuclear translocation of p65 and thereby provide a persistent "on signal" to NF-kappaB dependent gene transcription. Persistent activation of NF-kappaB may represent a mechanism by which nitric oxide sustains catabolic processes and promotes cartilage degeneration in osteoarthritis.
Clancy
R M
RM
Department of Rheumatology, Hospital for Joint Diseases, New York University School of Medicine, New York, NY 10003, USA. bobdclancy@aol.com
Gomez
P F
PF
Abramson
S B
SB
D000818:Animals; D002417:Cattle; D002478:Cells, Cultured; D019902:Chondrocytes / Q000187:drug effects* / Q000378:metabolism; D003545:Cysteine / Q000031:analogs & derivatives* / Q000494:pharmacology; D016207:Cytokines / Q000378:metabolism; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005455:Fluorescent Antibody Technique / Q000379:methods; D016166:Free Radical Scavengers / Q000494:pharmacology*; D015151:Immunoblotting / Q000379:methods; D016328:NF-kappa B / Q000378:metabolism*; D009569:Nitric Oxide / Q000494:pharmacology*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D019001:Nitric Oxide Synthase / Q000032:analysis; D052247:Nitric Oxide Synthase Type II; D009603:Nitroso Compounds / Q000494:pharmacology; D030421:Peroxynitrous Acid / Q000494:pharmacology; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D019323:omega-N-Methylarginine / Q000494:pharmacology
D016207:Cytokines; D004791:Enzyme Inhibitors; D016166:Free Radical Scavengers; D016328:NF-kappa B; D020030:Nitric Oxide Donors; D009603:Nitroso Compounds; C429310:S-nitrosocysteine ethyl ester; D030421:Peroxynitrous Acid; D019323:omega-N-Methylarginine; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; D003545:Cysteine