Induced nitric oxide inhibits IL-6-induced stat3 activation and type II acute phase mRNA expression.
Inducible nitric oxide synthase (iNOS) can be coexpressed with acute phase reactants in hepatocytes; however, it is unknown if NO can regulate the acute phase response. We tested the hypothesis that iNOS-derived nitric oxide (NO) attenuates the acute phase response by inhibiting IL-6-enhanced Stat3 DNA-binding activity and type II acute phase mRNA expression. iNOS was overexpressed in cultured rat hepatocytes via transduction with a replication defective adenovirus containing cDNA for human iNOS (AdiNOS), and Stat3 DNA-binding activity was determined by electrophoretic mobility shift assay (EMSA). EMSAs demonstrated that AdiNOS inhibits IL-6-induced Stat3 activation and that this inhibition is reversible in the presence of the NOS inhibitor N(G)-monomethyl-L-arginine (L-NMA). The induction of beta-fibrinogen mRNA by IL-6, a Stat3 dependent process, is attenuated in AdiNOS-transduced cells and partially reversed by L-NMA. Thus, iNOS overexpression suppresses IL-6-induced Stat3 activation and type II acute phase mRNA expression in cultured hepatocytes. This suppression may represent a mechanism by which NO down-regulates the acute phase response.
Villavicencio
R T
RT
Department of Surgery, University of Pittsburgh, Pennsylvania 15261, USA.
Liu
S
S
Kibbe
M R
MR
Williams
D L
DL
Ganster
R W
RW
Dyer
K F
KF
Tweardy
D J
DJ
Billiar
T R
TR
Pitt
B R
BR
D000210:Acute-Phase Reaction / Q000235:genetics*; D000818:Animals; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005340:Fibrinogen / Q000235:genetics; D005786:Gene Expression Regulation / Q000187:drug effects*; D006801:Humans; D008099:Liver / Q000187:drug effects / Q000378:metabolism; D008297:Male; D009566:Nitrates / Q000378:metabolism; D009569:Nitric Oxide / Q000494:pharmacology*; D019001:Nitric Oxide Synthase / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D052247:Nitric Oxide Synthase Type II; D009573:Nitrites / Q000378:metabolism; D010766:Phosphorylation; D011499:Protein Processing, Post-Translational; D012333:RNA, Messenger / Q000096:biosynthesis* / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D050796:STAT3 Transcription Factor; D015534:Trans-Activators / Q000378:metabolism*; D014162:Transfection; D019323:omega-N-Methylarginine / Q000494:pharmacology; D000093242:Interleukin-6 Inhibitors
D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D005340:Fibrinogen; D009566:Nitrates; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; D009573:Nitrites; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D050796:STAT3 Transcription Factor; D015534:Trans-Activators; D019323:omega-N-Methylarginine; D000093242:Interleukin-6 Inhibitors; C494086:STAT3 protein, human; C494088:Stat3 protein, rat; C496319:NOS2 protein, human; C496318:Nos2 protein, rat