title: Acute IL-3 priming up-regulates the stimulus-induced Raf-1-Mek-Erk cascade independently of IL-3-induced activation of Erk.
abstract: IL-3 is a potent priming cytokine for human basophils, inducing an increase of mediator release after stimulation. The mechanism of IL-3 priming of the basophil response to FcepsilonRI aggregating stimuli remains unknown. We explored the regulation of several elements of IgE-mediated signaling by a short priming with IL-3. Early signaling events such as phosphorylation of Syk, Shc, linker for activation of T cells, and the calcium signal were not statistically affected by acute IL-3 priming. Downstream in the signaling cascade, a point of up-regulation was found at the level of Raf-1-Mek-Erk. Although the phosphorylation of Raf-1 was not changed by IL-3 priming, IL-3-primed anti-IgE-stimulated basophils showed a strong synergism for Mek and Erk phosphorylation when compared with either IL-3 or anti-IgE alone; pre-exposure to IL-3 induced a final 13-fold average increase over anti-IgE-induced Erk phosphorylation (6-fold above the sum of anti-IgE and IL-3 alone). The kinetics, dose response, and pharmacologic characteristics of the IL-3 priming of stimulus-induced Erk phosphorylation support the involvement of a yet unknown mechanism that is independent of IL-3-induced Erk and PI3K activation. This type of preactivation can be mimicked by incubation with the Ser-Thr kinase inhibitors, Ro-81-3220, or bisindoylmaleimide II.
authors.affiliation: Johns Hopkins Asthma and Allergy Center, Baltimore, MD 21224, USA.
authors.forename: Natalia
authors.initials: N
authors.lastname: Vilariño
authors.forename: Katsushi
authors.initials: K
authors.lastname: Miura
authors.forename: Donald W
authors.initials: DW
authors.lastname: MacGlashan
mesh_terms: D002867:Chromones / Q000494:pharmacology; D004789:Enzyme Activation; D048049:Extracellular Signal-Regulated MAP Kinases / Q000502:physiology*; D006801:Humans; D007211:Indoles / Q000494:pharmacology; D007377:Interleukin-3 / Q000494:pharmacology*; D017997:Leukotriene C4 / Q000378:metabolism; D020930:MAP Kinase Kinase Kinases / Q000502:physiology*; D009025:Morpholines / Q000494:pharmacology; D010766:Phosphorylation; D019908:Proto-Oncogene Proteins c-raf / Q000502:physiology*; D015398:Signal Transduction / Q000502:physiology*; D015854:Up-Regulation
chemical_list: D002867:Chromones; D007211:Indoles; D007377:Interleukin-3; D009025:Morpholines; D017997:Leukotriene C4; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; D019908:Proto-Oncogene Proteins c-raf; D048049:Extracellular Signal-Regulated MAP Kinases; D020930:MAP Kinase Kinase Kinases; C064758:Ro 31-8220