The effect of IL-5 treatment on the stimulation-induced phosphorylation of proteins in blood eosinophils.
Eosinophils are selectively primed and activated by the cytokine IL-5. The aim of this investigation was to study the effects of IL-5 treatment on stimulation-dependent protein phosphorylations, in human peripheral blood eosinophils. After IL-5 treatment, basal phosphorylation patterns showed increases in the phosphorylation of 67, 80 and 93 kDa proteins. Cell stimulations resulted in the following protein phosphorylation increases: 50, 60, 67, 80 and 93 kDa (PMA); 50, 67, 80 and 93 kDa (STZ); and 67, 80 and 93 kDa (IL-5). The phosphorylation of the 50 and 60 kDa proteins was shown to be MEK-independent and dependent on some PKC isoform/s, whereas that of the 67, 80 and 93 kDa proteins was both MEK- and PKC-alpha, beta, delta, gamma, tau and zeta-independent. A phosphoprotein of 50 kDa was identified as p47(phox) and another of 67 kDa protein as the tyrosine phosphatase SHPTP-1. Incubation with IL-5 followed by cell stimulation increased the total phosphorylation of p47(phox). Bidimensional (IEF-SDS/PAGE) analysis showed that the combination of IL-5 treatment followed by stimulation with either PMA or STZ induced the formation of an additional, hyperphosphorylated form of p47(phox). The presence of this form would explain the higher NADPH oxidase activity normally observed after IL-5 priming.
Asthma Research Centre, University of Uppsala, Uppsala, Sweden.
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Woschnagg
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Venge
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Garcia
D004804:Eosinophils / Q000187:drug effects* / Q000378:metabolism*; D005260:Female; D006801:Humans; D047468:Immunoprecipitation; D015848:Interleukin-5 / Q000494:pharmacology*; D047908:Intracellular Signaling Peptides and Proteins / Q000494:pharmacology; D008297:Male; D008970:Molecular Weight; D010750:Phosphoproteins / Q000737:chemistry / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects
D015848:Interleukin-5; D047908:Intracellular Signaling Peptides and Proteins; D010750:Phosphoproteins; C015482:protein kinase modulator