The activation of the Jak-STAT 1 signaling pathway by IL-5 in eosinophils

K. Pazdrak, S. Stafford, R. Alam

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    Abstract

    The intracellular signal transduction of IL-5 in eosinophils is unknown. The objective of this study was to investigate the involvement of the newly discovered Jak-STAT pathway in the IL-5 signal transduction mechanism. Eosinophils were purified from peripheral blood by discontinuous Percoll gradients and stimulated with IL-5. The involvement of Jak 2 was investigated by immunoprecipitation followed by immunoblotting for tyrosine phosphorylation. The activation of Jak 2 was studied by autophosphorylation of the immunoprecipitated kinase. Jak 2 was tyrosine phosphorylated within 1 to 3 min after stimulation of eosinophils with IL-5. Further, the immunoprecipitated Jak 2 obtained from IL-5-stimulated cells underwent autophosphorylation. Jak 2 coprecipitated with the β-subunit of the IL-5 receptor, suggesting a physical association of the kinase with the receptor. The nuclear factor STAT-1 (p91) was investigated by immunoprecipitation followed by immunoblotting for tyrosine phosphorylation. STAT-1 was tyrosine phosphorylated within 15 min of IL-5 stimulation. The presence of STAT-1 in the nuclear extract was studied by electrophoretic mobility shift assay. IL- 5 induced two proteins that bound to the γ-activating sequence. In the presence of an anti-STAT-1 Ab, the band was supershifted. Thus, we demonstrated that IL-5 activated the Jak 2-STAT 1 signaling pathway in eosinophils. We speculate that the Jak 2-STAT 1 pathway may be involved in the activation of IL-5 inducible genes in eosinophils.

    Original languageEnglish (US)
    Pages (from-to)397-402
    Number of pages6
    JournalJournal of Immunology
    Volume155
    Issue number1
    StatePublished - Jan 1 1995

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    ASJC Scopus subject areas

    • Immunology and Allergy
    • Immunology

    Cite this

    Pazdrak, K., Stafford, S., & Alam, R. (1995). The activation of the Jak-STAT 1 signaling pathway by IL-5 in eosinophils. Journal of Immunology, 155(1), 397-402.