title: A new role for monoamine oxidases in the modulation of macrophage-inducible nitric oxide synthase gene expression.
abstract: This report focuses on the modulatory role of endogenous H(2)O(2) on lipopolysaccharide (LPS)/interferon-gamma (IFN-gamma)-induced inducible nitric oxide synthase (NOS2) gene expression in rat peritoneal macrophages. Exogenously added H(2)O(2) was initially found to inhibit the synthesis of NOS2, which prompted us to assess the effect of the activity of monoamine oxidase (MAO) and semicarbazide-sensitive amine oxidase (SSAO) as H(2)O(2)-forming enzymes on NOS2 gene expression. In the presence of their substrates, tyramine for MAO and benzylamine for SSAO, intracellular synthesis of H(2)O(2) took place with concomitant inhibition of LPS/IFN-gamma-induced NOS2 protein synthesis, as detected by Western blotting, flow cytometry, and immunofluorescence microscopy analyses. Pargyline and semicarbazide, specific inhibitors of MAO and SSAO, respectively, canceled this negative effect of MAO substrates on NOS2 expression. In the presence of Fe(2+) and Cu(2+) ions, inhibition of NOS2 expression was enhanced, suggesting the participation in this regulation of species derived from Fenton chemistry. In addition, the negative effect of H(2)O(2), generated by MAOs, was found to be exerted on NOS2 mRNA levels. These data offer a new insight in the control of NOS2 expression through the intracellular levels of H(2)O(2) and other reactive oxygen species (ROS). The hypothesis can be raised that the inhibition of NOS by H(2)O(2) could constitute a protective mechanism against the cytotoxic consequences of the activation of ROS-generating enzymes, thus providing a new, singular role for the MAO family of proteins.
authors.affiliation: Facultad de Medicina, Universidad de Sevilla, Avda. Sánchez Pizjuán 4, 41009-Sevilla, Spain.
authors.forename: Antonio
authors.initials: A
authors.lastname: Vega
authors.forename: Pedro
authors.initials: P
authors.lastname: Chacón
authors.forename: Javier
authors.initials: J
authors.lastname: Monteseirín
authors.forename: Rajaa
authors.initials: R
authors.lastname: El Bekay
authors.forename: Moisés
authors.initials: M
authors.lastname: Alvarez
authors.forename: Gonzalo
authors.initials: G
authors.lastname: Alba
authors.forename: José
authors.initials: J
authors.lastname: Conde
authors.forename: José
authors.initials: J
authors.lastname: Martín-Nieto
authors.forename: Francisco J
authors.initials: FJ
authors.lastname: Bedoya
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Pintado
authors.forename: Francisco
authors.initials: F
authors.lastname: Sobrino
mesh_terms: D006631:Amine Oxidase (Copper-Containing) / Q000235:genetics / Q000378:metabolism; D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology; D015153:Blotting, Western; D004357:Drug Synergism; D005434:Flow Cytometry; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology*; D006861:Hydrogen Peroxide / Q000378:metabolism / Q000494:pharmacology; D007371:Interferon-gamma / Q000494:pharmacology; D008070:Lipopolysaccharides / Q000494:pharmacology; D017737:Macrophages, Peritoneal / Q000201:enzymology*; D008297:Male; D008856:Microscopy, Fluorescence; D008995:Monoamine Oxidase / Q000502:physiology*; D009569:Nitric Oxide / Q000037:antagonists & inhibitors; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors / Q000235:genetics*; D052247:Nitric Oxide Synthase Type II; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D014638:Vanadates / Q000494:pharmacology
chemical_list: D000970:Antineoplastic Agents; D008070:Lipopolysaccharides; D012333:RNA, Messenger; D009569:Nitric Oxide; D014638:Vanadates; D007371:Interferon-gamma; D006861:Hydrogen Peroxide; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496318:Nos2 protein, rat; D006631:Amine Oxidase (Copper-Containing); D008995:Monoamine Oxidase