title: Localizing a control region in the pathway to leukotriene C(4) secretion following stimulation of human basophils with anti-IgE antibody.
abstract: Mediator release from human basophils is a self-limited process, but down-regulation of the signaling cascades leading to secretion of leukotriene C(4) (LTC(4)) is controlled independently of the pathway leading to IL-4 secretion. In the current studies, we have explored the regulation of upstream signaling events leading to activation of extracellular signal-related kinases (ERKs; previously shown to be required for LTC(4) generation) in human basophils. IgE-, but not FMLP-mediated activation, induced sustained tyrosine phosphorylation of syk, of shc, and an association of shc to the Grb2/son of sevenless 2 complex. In contrast, IgE-mediated activation resulted in transient activation of p21(ras) and mitogen-activated protein/ERK kinase 1, which were kinetically associated with phosphorylation of ERKs. The canonical Shc/Grb2/son of sevenless pathway to activation of p21(ras) is therefore sustained, while p21(ras) activity is not. We have previously shown that phosphatidylinositol 3 kinase activity is required for p21(ras) activity and, in the current studies, we show that of the p85-sensitive forms of p110 possible, basophils express only p110 delta and that there are no changes in association between p21(ras) and p110 delta in stimulated basophils. We used the generation of phospho-Akt as a marker of the presence of phosphatidylinositol-3,4,5-trisphosphate and found that phospho-Akt is transient on a time scale consistent with p21(ras) activity. On the basis of information obtained in these and other studies, we localize down-regulation of IgE-mediated LTC(4) secretion to a region of the signaling cascade antecedent to p21(ras) activation, downstream of phosphatidylinositol 3 kinase activity and probably involving regulation of phosphatidylinositol-3,4,5-trisphosphate levels.
authors.affiliation: Johns Hopkins Asthma and Allergy Center, Baltimore, MD 21224, USA.
authors.forename: K
authors.initials: K
authors.lastname: Miura
authors.forename: S
authors.initials: S
authors.lastname: Lavens-Phillips
authors.forename: D W
authors.initials: DW
authors.lastname: MacGlashan
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; D000888:Antibodies, Anti-Idiotypic / Q000494:pharmacology*; D001491:Basophils / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D007700:Kinetics; D017997:Leukotriene C4 / Q000378:metabolism*; D048369:MAP Kinase Kinase 1; D020935:MAP Kinase Signaling System; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D008954:Models, Biological; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011506:Proteins / Q000378:metabolism; D016283:Proto-Oncogene Proteins p21(ras) / Q000378:metabolism; D011720:Pyrazoles / Q000494:pharmacology; D011743:Pyrimidines / Q000494:pharmacology; D055765:Shc Signaling Adaptor Proteins; D000071425:Src Homology 2 Domain-Containing, Transforming Protein 1; D019061:src-Family Kinases / Q000037:antagonists & inhibitors
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; D000888:Antibodies, Anti-Idiotypic; D004791:Enzyme Inhibitors; D017997:Leukotriene C4; D048369:MAP Kinase Kinase 1; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020929:Mitogen-Activated Protein Kinase Kinases; D020928:Mitogen-Activated Protein Kinases; D009240:N-Formylmethionine Leucyl-Phenylalanine; D019869:Phosphatidylinositol 3-Kinases; D017346:Protein Serine-Threonine Kinases; D011506:Proteins; D016283:Proto-Oncogene Proteins p21(ras); D011720:Pyrazoles; D011743:Pyrimidines; D055765:Shc Signaling Adaptor Proteins; D000071425:Src Homology 2 Domain-Containing, Transforming Protein 1; D019061:src-Family Kinases; C108123:4-amino-5-(4-methylphenyl)-7-(tert-butyl)pyrazolo(3,4-d)pyrimidine; C528024:SHC1 protein, human; C026408:anti-IgE antibodies; C060902:lyn protein-tyrosine kinase; C482125:MAP2K1 protein, human; C501009:HRAS protein, human