Regulation of cytokine-induced nitric oxide synthesis by asymmetric dimethylarginine: role of dimethylarginine dimethylaminohydrolase.
In response to vascular insults, inflammatory cytokines stimulate vascular smooth muscle cells (SMCs) to express an inducible isoform of nitric oxide synthase (iNOS). Asymmetric dimethylarginine (ADMA), an endogenous NO synthase inhibitor, is metabolized by dimethylarginine dimethylaminohydrolase (DDAH). To determine whether the ADMA-DDAH system regulates cytokine-induced NO production, cultured rat SMCs were exposed to interleukin-1beta (IL-1beta). IL-1beta (1 to 100 U/mL) dose-dependently stimulated not only iNOS but also DDAH expression and enzyme activity, accompanied by an increase in NO metabolite and by a decrease in ADMA content in culture media. A DDAH inhibitor (4124W, 5 mmol/L) augmented ADMA production (P<0.01) and decreased NO synthesis (P<0.01) in IL-1beta-stimulated SMCs. On the other hand, an adenovirus-mediated overexpression of DDAH reduced ADMA and enhanced NO production. Exogenous administration of NO donors (SNAP and SIN-1) dose-dependently increased NO metabolite in the culture media but had no effect on ADMA. Our results indicate two mechanisms of IL-1beta-induced NO synthesis: the direct stimulation of the expression of iNOS and the indirect stimulation of iNOS activity by upregulating DDAH and reducing ADMA. The ADMA-DDAH system may be another regulatory mechanism of inflammation-mediated NO production for human vascular diseases.
Ueda
Seiji
S
Department of Internal Medicine III and the Cardiovascular Research Institute, Kurume University School of Medicine, Kurume, Japan.
Kato
Seiya
S
Matsuoka
Hidehiro
H
Kimoto
Masumi
M
Okuda
Seiya
S
Morimatsu
Minoru
M
Imaizumi
Tsutomu
T
D000581:Amidohydrolases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives* / Q000378:metabolism* / Q000494:pharmacology; D002478:Cells, Cultured; D017077:Culture Media, Conditioned / Q000737:chemistry / Q000378:metabolism; D016207:Cytokines / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007375:Interleukin-1 / Q000494:pharmacology*; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D009569:Nitric Oxide / Q000096:biosynthesis*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D019001:Nitric Oxide Synthase / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II; D051381:Rats; D017207:Rats, Sprague-Dawley; D014162:Transfection
D017077:Culture Media, Conditioned; D016207:Cytokines; D004791:Enzyme Inhibitors; D007375:Interleukin-1; D020030:Nitric Oxide Donors; D009569:Nitric Oxide; C018524:N,N-dimethylarginine; D001120:Arginine; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496318:Nos2 protein, rat; D000581:Amidohydrolases; C059999:dimethylargininase