Nitric oxide provokes tumor necrosis factor-alpha expression in adult feline myocardium through a cGMP-dependent pathway.
BACKGROUND
The mechanism(s) responsible for the persistent coexpression of tumor necrosis factor-alpha (TNF-alpha) and nitric oxide (NO) in the failing heart is unknown.


RESULTS
To determine whether NO was sufficient to provoke TNF-alpha biosynthesis, we examined the effects of an NO donor, S-nitroso-N-acetyl penicillamine (SNAP), in buffer-perfused Langendorff hearts. SNAP (1 micromol/L) treatment resulted in a time- and dose-dependent increase in myocardial TNF-alpha mRNA and protein biosynthesis in adult cat hearts. The effects of SNAP were completely abrogated by a NO quenching agent, 2-(4-carboxyphenyl)-4, 4,5,5-tetramethylimidazoline-1-oxyl 3-oxide (C-PTIO), and mimicked by sodium nitroprusside. Electrophoretic mobility shift assays demonstrated that SNAP treatment led to the rapid induction of nuclear factor kappa-beta (NF-kappaB) but not AP-1. The importance of the cGMP pathway in terms of mediating NO-induced TNF-alpha biosynthesis was shown by studies that demonstrated that 8-bromo-cGMP mimicked the effects of SNAP and that the effects of SNAP could be completely abrogated using a cGMP antagonist, 1H-(1,2, 4)oxadiazolo(4,3-a)quinoxalin-1-one (ODQ), or protein kinase G antagonist (Rp-8-Br-cGMPS). SNAP and 8-Br-cGMP were both sufficient to lead to the site-specific phosphorylation (serine 32) and degradation of IkappaBalpha in isolated cardiac myocytes. Finally, protein kinase G was sufficient to directly phosphorylate IkappaBalpha on serine 32, a critical step in the activation of NF-kappaB.


CONCLUSIONS
These studies show that NO provokes TNF-alpha biosynthesis through a cGMP-dependent pathway, which suggests that the coincident expression of TNF-alpha and NO may foster self-sustaining positive autocrine/paracrine feedback inflammatory circuits within the failing heart.
Kalra
D
D
Winters Center for Heart Failure Research, Cardiology Section, Department of Medicine, Veterans Administration Medical Center and Baylor College of Medicine, Houston, TX 77030, USA.
Baumgarten
G
G
Dibbs
Z
Z
Seta
Y
Y
Sivasubramanian
N
N
Mann
D L
DL
D000818:Animals; D001565:Benzoates / Q000494:pharmacology; D002415:Cats; D006152:Cyclic GMP / Q000031:analogs & derivatives* / Q000037:antagonists & inhibitors / Q000494:pharmacology / Q000502:physiology*; D017869:Cyclic GMP-Dependent Protein Kinases; D004268:DNA-Binding Proteins / Q000378:metabolism; D004586:Electrophoresis / Q000379:methods; D020672:I-kappa B Proteins; D007093:Imidazoles / Q000494:pharmacology; D066298:In Vitro Techniques; D009206:Myocardium / Q000378:metabolism*; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000096:biosynthesis; D009569:Nitric Oxide / Q000378:metabolism*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D009599:Nitroprusside / Q000494:pharmacology; D010069:Oxadiazoles / Q000494:pharmacology; D010396:Penicillamine / Q000031:analogs & derivatives* / Q000494:pharmacology; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism; D011810:Quinoxalines / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D013873:Thionucleotides / Q000494:pharmacology; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis*
C095284:1H-(1,2,4)oxadiazolo(4,3-a)quinoxalin-1-one; D001565:Benzoates; D004268:DNA-Binding Proteins; D020672:I-kappa B Proteins; D007093:Imidazoles; D016328:NF-kappa B; D020030:Nitric Oxide Donors; D010069:Oxadiazoles; D011810:Quinoxalines; D012333:RNA, Messenger; C110881:S-nitro-N-acetylpenicillamine; D013873:Thionucleotides; D014409:Tumor Necrosis Factor-alpha; D000072000:NF-KappaB Inhibitor alpha; C079393:1,3-dihydroxy-4,4,5,5-tetramethyl-2-(4-carboxyphenyl)tetrahydroimidazole; C083763:8-bromoguanosino-3',5'-cyclic monophosphorothioate; D009599:Nitroprusside; C016276:8-bromocyclic GMP; D009569:Nitric Oxide; D011494:Protein Kinases; D017869:Cyclic GMP-Dependent Protein Kinases; D010396:Penicillamine; D006152:Cyclic GMP