Role of tyrosine kinase activity in signal transduction by the insulin- like growth factor-I (IGF-I) receptor. Characterization of kinase-deficient IGF-I receptors and the action of an IGF-I-mimetic antibody (αIR-3)

H. Kato, T. N. Faria, B. Stannard, C. T. Roberts, D. LeRoith

    Research output: Contribution to journalArticle

    238 Scopus citations

    Abstract

    The insulin-like growth factor-I (IGF-I) receptor is a member of a large family of transmembrane signal transducing molecules. The defining characteristic of this class of receptors is the intrinsic tyrosine kinase activity of the cytoplasmic domain. While it has been demonstrated that this tyrosine kinase activity is necessary for the action of a number of transmembrane tyrosine kinase receptors, no evidence of this type has been adduced to date with respect to the signaling requirement of the IGF-I receptor. We have now shown that stably transfected NIH-3T3 cell lines overexpressing human IGF-I receptors display increased responses to IGF-I and an IGF-I-mimetic antibody, αIR-3, in terms of short, intermediate, and long term actions initiated by activation of the IGF-I receptor. These include receptor autophosphorylation, activation of phosphatidylinositol-3-kinase and 2-deoxyglucose uptake, induction of ornithine decarboxylase gene expression, and stimulation of thymidine incorporation. In short term responses, the kinetics seen with αIR-3 were slower than those seen with IGF-I. These effects were severely decreased in clones expressing human IGF-I receptors in which the lysine residue in the ATP-binding site of the tyrosine kinase domain had been mutated to alanine or arginine. This was true for both IGF-I and αIR-3. These results indicate that, for all parameters tested, the tyrosine kinase activity of the IGF-I receptor is necessary for activation of the IGF-I-stimulated signal transduction cascade. Additionally, the effects of αIR-3 also require tyrosine kinase activity.

    Original languageEnglish (US)
    Pages (from-to)2655-2661
    Number of pages7
    JournalJournal of Biological Chemistry
    Volume268
    Issue number4
    StatePublished - Jan 1 1993

    ASJC Scopus subject areas

    • Biochemistry
    • Molecular Biology
    • Cell Biology

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