Hepatic flavin-containing monooxygenase activity attenuated by cGMP-independent nitric oxide-mediated mRNA destabilization.
To identify the novel mechanism by which nitric oxide (NO) suppresses flavin-containing monooxygenase (FMO) activity in endotoxemic rat livers, NO-overproducing conditions were induced in primary cultured rat hepatocytes by treatment with a mixture (LCM) of lipopolysaccharide and proinflammatory cytokines (IL-1beta, TNF-alpha, and IFN-gamma), or by the addition of a pure NO donor, spermine-NONOate. mRNA levels of the major hepatic form, FMO1, decreased via a cGMP-independent destabilizing effect of NO rather than by decreased transcription. The decrease in the mRNA levels caused by LCM-induced inducible NO synthase (iNOS) was completely blocked by co-treatment with aminoguanidine, a selective iNOS inhibitor. Furthermore, spermine-NONOate, but not the cGMP analog, 8-bromo-cGMP, dose- and time-dependently attenuated FMO1 mRNA stability in actinomycin-D-pretreated cells, resulting in decreases in protein levels and biochemical activity. These results suggest that NO acts directly in a cGMP-independent mechanism by decreasing the half-life of FMO1 mRNA, thereby inducing impairment of FMO-related functions in endotoxemia.
Department of Pharmacology and Toxicology, College of Medicine, Medicinal Toxicology Research Center, CDIR, Inha University, Incheon 400-103, Republic of Korea.
Seung-Duk
SD
Ryu
Ju-Hee
JH
Kang
Hyeon-Gyu
HG
Yi
Chung-Hyun
CH
Nahm
Chang-Shin
CS
Park
D000818:Animals; D002478:Cells, Cultured; D006152:Cyclic GMP / Q000031:analogs & derivatives / Q000378:metabolism*; D016207:Cytokines / Q000494:pharmacology; D003609:Dactinomycin / Q000494:pharmacology; D006146:Guanidines / Q000494:pharmacology; D022781:Hepatocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D008070:Lipopolysaccharides / Q000494:pharmacology; D008099:Liver / Q000166:cytology / Q000201:enzymology*; D008297:Male; D009569:Nitric Oxide / Q000378:metabolism*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D052247:Nitric Oxide Synthase Type II; D009589:Nitrogen Oxides; D010105:Oxygenases / Q000235:genetics* / Q000378:metabolism*; D046188:Protein Modification, Translational; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D020871:RNA Stability; D051381:Rats; D017207:Rats, Sprague-Dawley; D013096:Spermine / Q000031:analogs & derivatives* / Q000494:pharmacology
D016207:Cytokines; D006146:Guanidines; D008070:Lipopolysaccharides; D020030:Nitric Oxide Donors; D009589:Nitrogen Oxides; D011500:Protein Synthesis Inhibitors; C091861:spermine nitric oxide complex; D003609:Dactinomycin; D013096:Spermine; D009569:Nitric Oxide; D010105:Oxygenases; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496318:Nos2 protein, rat; C020066:dimethylaniline monooxygenase (N-oxide forming); D006152:Cyclic GMP; C004479:pimagedine