title: CD14-dependent mechanism for endotoxin-mediated nitric oxide synthesis in murine macrophages.
abstract: Endotoxin-mediated macrophage synthesis of nitric oxide (NO) is associated with immune effector function, intercellular communication, leukocyte adhesion, vascular integrity, and neurotransmission. However, little is known of the cellular receptor and signal transduction pathway by which endotoxin induces NO production. With the use of a model of ANA-1 murine macrophages, we stimulated NO production by incubation with increasing concentrations of endotoxin and 5% fetal calf serum. In selected instances, the anti-CD14 antibody, ED9, was added. Endotoxin-mediated NO synthesis was dependent on CD14 function and the presence of an additional serum factor. Endotoxin treatment increased plasma membrane GTPase activity and 35S-labeled guanosine 5'-O-(3-thiotriphosphate) ([35S]GTP gamma S) binding. Conversely, coincubation of cells with endotoxin and the heterotrimeric G protein inhibitors, suramin and guanosine 5'-O-(2-thiodiphosphate) trilithium salt, was associated with decreased NO synthesis, plasma membrane GTPase activity, and [35S]GTP gamma S binding. Blockade of CD14 or G protein function was associated with ablation of endotoxin-mediated inducible NO synthase (iNOS) protein expression, iNOS mRNA levels, and iNOS gene transcription, as determined by immunoblot, reverse transcriptase-polymerase chain reaction, and nuclear run-on analyses, respectively. These results indicate that endotoxin-mediated NO synthesis is a CD14-heterotrimeric G protein-dependent process.
authors.affiliation: Department of Surgery, University of Maryland Medical System, Baltimore 21201, USA.
authors.forename: R A
authors.initials: RA
authors.lastname: Schroeder
authors.forename: A
authors.initials: A
authors.lastname: delaTorre
authors.forename: P C
authors.initials: PC
authors.lastname: Kuo
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D002460:Cell Line; D002462:Cell Membrane / Q000502:physiology; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D017931:DNA Primers; D004731:Endotoxins / Q000494:pharmacology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004926:Escherichia coli; D020558:GTP Phosphohydrolases / Q000378:metabolism; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000494:pharmacology; D006153:Guanosine Diphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D007700:Kinetics; D018950:Lipopolysaccharide Receptors / Q000276:immunology / Q000502:physiology*; D008070:Lipopolysaccharides / Q000494:pharmacology; D008264:Macrophages / Q000187:drug effects / Q000502:physiology*; D051379:Mice; D009281:Naphthalenes / Q000494:pharmacology; D009569:Nitric Oxide / Q000096:biosynthesis*; D019001:Nitric Oxide Synthase / Q000096:biosynthesis*; D016133:Polymerase Chain Reaction; D011493:Protein Kinase C / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D051381:Rats; D013498:Suramin / Q000494:pharmacology; D013873:Thionucleotides / Q000494:pharmacology
chemical_list: D000911:Antibodies, Monoclonal; D017931:DNA Primers; D004731:Endotoxins; D004791:Enzyme Inhibitors; D018950:Lipopolysaccharide Receptors; D008070:Lipopolysaccharides; D009281:Naphthalenes; D013873:Thionucleotides; C061465:calphostin complex; D006153:Guanosine Diphosphate; C032829:6-thioguanosine 5'-diphosphate; D009569:Nitric Oxide; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D013498:Suramin; D019001:Nitric Oxide Synthase; D011505:Protein-Tyrosine Kinases; D011493:Protein Kinase C; D020558:GTP Phosphohydrolases