title: Ceramide-mediated stimulation of inducible nitric oxide synthase (iNOS) and tumor necrosis factor (TNF) accumulation in murine macrophages requires tyrosine kinase activity.
abstract: In macrophages, bacterial lipopolysaccharide (LPS) has been noted to mimic certain effects of the sphingolipid ceramide, suggesting that ceramide may be involved in macrophage activation by LPS and/or that LPS utilizes ceramide-related signaling pathways. Putative downstream targets of ceramide include a ceramide-activated (serine/threonine) protein kinase (CAPK) and phosphatase (CAPP). However, the potential role of tyrosine phosphorylation pathways in macrophage response to ceramide has not been examined. Herein we report that cell-permeable analogs of ceramide up-regulate both inducible nitric oxide synthase (iNOS) and tumor necrosis factor (TNF) production in RAW 264.7 murine macrophages. Herbimycin A and genistein, potent natural inhibitors of protein tyrosine (but not serine/threonine) phosphorylation, block ceramide-induced iNOS and TNF production. Furthermore, the highly src-family selective pyrazolopyrimidine inhibitor PP1 also blocks ceramide-induced iNOS and TNF production in RAW 264.7 cells. We found that PP1 also inhibits ceramide-mediated tyrosine phosphorylation of the src-family kinase hck. These data indicate that src-related tyrosine kinases play a critical role in macrophage activation by ceramide.
authors.affiliation: Crippled Children's Foundation Research Center at Le Bonheur Children's Medical Center, Department of Pediatrics, University of Tennessee, Memphis 38103, USA. kknapp@utmem.edu
authors.forename: K M
authors.initials: KM
authors.lastname: Knapp
authors.forename: B K
authors.initials: BK
authors.lastname: English
mesh_terms: D000818:Animals; D016227:Benzoquinones; D002460:Cell Line; D002518:Ceramides / Q000494:pharmacology*; D004790:Enzyme Induction; D004791:Enzyme Inhibitors / Q000494:pharmacology; D019833:Genistein / Q000494:pharmacology; D007371:Interferon-gamma / Q000494:pharmacology; D047029:Lactams, Macrocyclic; D008262:Macrophage Activation / Q000502:physiology; D008264:Macrophages / Q000187:drug effects / Q000276:immunology / Q000502:physiology*; D051379:Mice; D019001:Nitric Oxide Synthase / Q000096:biosynthesis*; D052247:Nitric Oxide Synthase Type II; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D011809:Quinones / Q000494:pharmacology; D011994:Recombinant Proteins; D017828:Rifabutin / Q000031:analogs & derivatives; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000494:pharmacology; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis*
chemical_list: D016227:Benzoquinones; D002518:Ceramides; D004791:Enzyme Inhibitors; D047029:Lactams, Macrocyclic; C064769:N-acetylsphingosine; D011809:Quinones; D011994:Recombinant Proteins; D014409:Tumor Necrosis Factor-alpha; C101954:N-caproylsphingosine; D017828:Rifabutin; C020754:herbimycin; D007371:Interferon-gamma; D019833:Genistein; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse; D011505:Protein-Tyrosine Kinases; D013110:Sphingosine