Differential activation of insulin receptor substrates 1 and 2 by insulin-like growth factor-activated insulin receptors

Adam Denley, Julie M. Carroll, Gemma V. Brierley, Leah Cosgrove, John Wallace, Briony Forbes, Charles Roberts

    Research output: Contribution to journalArticle

    75 Citations (Scopus)

    Abstract

    The insulin-like growth factors (insulin-like growth factor I [IGF-I] and IGF-II) exert important effects on growth, development, and differentiation through the IGF-I receptor (IGF-IR) transmembrane tyrosine kinase. The insulin receptor (IR) is structurally related to the IGF-IR, and at high concentrations, the IGFs can also activate the IR, in spite of their generally low affinity tor the latter. Two mechanisms that facilitate cross talk between the IGF ligands and the IR at physiological concentrations have been described. The first of these is the existence of an alternatively spliced IR variant that exhibits high affinity for IGF-II as well as for insulin. A second phenomenon is the ability of hybrid receptors comprised of IGF-IR and IR hemireceptors to bind IGFs, but not insulin. To date, however, direct activation of an IR holoreceptor by IGF-I at physiological levels has not been demonstrated. We have now found that IGF-I can function through both splice variants of the IR, in spite of low affinity, to specifically activate IRS-2 to levels similar to those seen with equivalent concentrations of insulin or IGF-II. The specific activation of IRS-2 by IGF-I through the IR does not result in activation of the extracellular signal-regulated kinase pathway but does induce delayed low-level activation of the phosphatidylinositol 3-kinase pathway and biological effects such as enhanced cell viability and protection from apoptosis. These findings suggest that IGF-I can function directly through the IR and that the observed effects of IGF-I on insulin sensitivity may be the result of direct facilitation of insulin action by IGF-I costimulation of the IR in insulin target tissues.

    Original languageEnglish (US)
    Pages (from-to)3569-3577
    Number of pages9
    JournalMolecular and Cellular Biology
    Volume27
    Issue number10
    DOIs
    StatePublished - May 2007

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    Insulin Receptor Substrate Proteins
    Insulin Receptor
    Somatomedins
    Insulin-Like Growth Factor I
    IGF Type 1 Receptor
    Insulin-Like Growth Factor II
    Insulin
    Phosphatidylinositol 3-Kinase
    Cytoprotection
    Extracellular Signal-Regulated MAP Kinases
    Growth and Development
    Protein-Tyrosine Kinases
    Insulin Resistance
    Cell Survival
    Apoptosis
    Ligands

    ASJC Scopus subject areas

    • Molecular Biology
    • Genetics
    • Cell Biology

    Cite this

    Differential activation of insulin receptor substrates 1 and 2 by insulin-like growth factor-activated insulin receptors. / Denley, Adam; Carroll, Julie M.; Brierley, Gemma V.; Cosgrove, Leah; Wallace, John; Forbes, Briony; Roberts, Charles.

    In: Molecular and Cellular Biology, Vol. 27, No. 10, 05.2007, p. 3569-3577.

    Research output: Contribution to journalArticle

    Denley, Adam ; Carroll, Julie M. ; Brierley, Gemma V. ; Cosgrove, Leah ; Wallace, John ; Forbes, Briony ; Roberts, Charles. / Differential activation of insulin receptor substrates 1 and 2 by insulin-like growth factor-activated insulin receptors. In: Molecular and Cellular Biology. 2007 ; Vol. 27, No. 10. pp. 3569-3577.
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