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https://hdl.handle.net/2440/43768
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Type: | Journal article |
Title: | Differential activation of insulin receptor substrates 1 and 2 by insulin-like growth factor-activated insulin receptors |
Author: | Denley, A. Carroll, J. Brierley, G. Cosgrove, L. Wallace, J. Forbes, B. Roberts, C. |
Citation: | Molecular and Cellular Biology, 2007; 27(10):3569-3577 |
Publisher: | Amer Soc Microbiology |
Issue Date: | 2007 |
ISSN: | 0270-7306 1098-5549 |
Statement of Responsibility: | Adam Denley, Julie M. Carroll, Gemma V. Brierley, Leah Cosgrove, John Wallace, Briony Forbes, and Charles T. Roberts |
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 for 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. |
Keywords: | Cell Line Animals Humans Mice Insulin Receptor, IGF Type 1 Receptor, Insulin Insulin-Like Growth Factor I Insulin-Like Growth Factor II Intracellular Signaling Peptides and Proteins Insulin-Like Growth Factor Binding Proteins Phosphoproteins Recombinant Fusion Proteins RNA, Small Interfering Signal Transduction Cell Survival Alternative Splicing Insulin Receptor Substrate Proteins |
Rights: | © 2007, American Society for Microbiology. All Rights Reserved. |
DOI: | 10.1128/MCB.01447-06 |
Published version: | http://mcb.asm.org/cgi/content/abstract/27/10/3569 |
Appears in Collections: | Aurora harvest Molecular and Biomedical Science publications |
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