Phosphorylation of human insulin receptor substrate-1 at serine 629 plays a positive role in insulin signaling

Moulun Luo, Paul Langlais, Zhengping Yi, Natalie Lefort, Elena A. De Filippis, Hyonson Hwang, Christine Y. Christ-Roberts, Lawrence J. Mandarino

    Research output: Contribution to journalArticle

    41 Citations (Scopus)

    Abstract

    The function of insulin receptor substrate-1 (IRS-1) is regulated by both tyrosine and serine/threonine phosphorylation. Phosphorylation of some serine/threonine residues in IRS-1 dampens insulin signaling, whereas phosphorylation of other serine/threonine residues enhances insulin signaling. Phosphorylation of human IRS-1 at Ser629 was increased by insulin in Chinese hamster ovary cells expressing the insulin receptor (1.26 ± 0.09-fold; P < 0.05) and L6 cells (1.35 ± 0.29-fold; P < 0.05) expressinghuman IRS-1. Sequence analysis surrounding Ser629 revealed conformity to the consensus phosphorylation sequence recognized by Akt. Phosphorylation of IRS-1 at Ser629 in cells was decreased upon treatment with either an Akt inhibitor or by coexpression with kinase dead Akt, whereas Ser629 phosphorylation was increased by coexpression with constitutively active Akt. In addition, Ser629 of IRS-1 is directly phosphorylated by Akt in vitro. In cells, preventing phosphorylation of Ser 629 by a Ser629Ala mutation resulted in increased phosphorylation of Ser636, a known negative regulator of IRS-1, without affecting phosphorylation of Tyr632 or Ser616. Cells expressing the Ser629Ala mutation, along with increased Ser636 phosphorylation, had decreased insulin-stimulated association of the p85 regulatory subunit of phosphatidylinositol 3′-kinase with IRS-1 and decreased phosphorylation of Akt at Ser473. Finally, in vitro phosphorylation of a Ser629-containing IRS-1 fragment with Akt reduces the subsequent ability of ERK to phosphorylate Ser636/639. These results suggest that a feed-forward mechanism may exist whereby insulin activation of Akt leads to phosphorylation of IRS-1 at Ser629, resulting in decreased phosphorylation of IRS-1 at Ser636 and enhanced downstream signaling. Understanding the complex phosphorylation patterns of IRS-1 is crucial to elucidating the factors contributing to insulin resistance and, ultimately, the pathogenesis of type 2 diabetes.

    Original languageEnglish (US)
    Pages (from-to)4895-4905
    Number of pages11
    JournalEndocrinology
    Volume148
    Issue number10
    DOIs
    StatePublished - Oct 2007

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    Insulin Receptor Substrate Proteins
    Serine
    Phosphorylation
    Insulin
    Threonine
    human INSR protein
    Phosphatidylinositol 3-Kinase
    Mutation
    Insulin Receptor
    Consensus Sequence

    ASJC Scopus subject areas

    • Endocrinology
    • Endocrinology, Diabetes and Metabolism

    Cite this

    Luo, M., Langlais, P., Yi, Z., Lefort, N., De Filippis, E. A., Hwang, H., ... Mandarino, L. J. (2007). Phosphorylation of human insulin receptor substrate-1 at serine 629 plays a positive role in insulin signaling. Endocrinology, 148(10), 4895-4905. https://doi.org/10.1210/en.2007-0049

    Phosphorylation of human insulin receptor substrate-1 at serine 629 plays a positive role in insulin signaling. / Luo, Moulun; Langlais, Paul; Yi, Zhengping; Lefort, Natalie; De Filippis, Elena A.; Hwang, Hyonson; Christ-Roberts, Christine Y.; Mandarino, Lawrence J.

    In: Endocrinology, Vol. 148, No. 10, 10.2007, p. 4895-4905.

    Research output: Contribution to journalArticle

    Luo, M, Langlais, P, Yi, Z, Lefort, N, De Filippis, EA, Hwang, H, Christ-Roberts, CY & Mandarino, LJ 2007, 'Phosphorylation of human insulin receptor substrate-1 at serine 629 plays a positive role in insulin signaling', Endocrinology, vol. 148, no. 10, pp. 4895-4905. https://doi.org/10.1210/en.2007-0049
    Luo, Moulun ; Langlais, Paul ; Yi, Zhengping ; Lefort, Natalie ; De Filippis, Elena A. ; Hwang, Hyonson ; Christ-Roberts, Christine Y. ; Mandarino, Lawrence J. / Phosphorylation of human insulin receptor substrate-1 at serine 629 plays a positive role in insulin signaling. In: Endocrinology. 2007 ; Vol. 148, No. 10. pp. 4895-4905.
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    abstract = "The function of insulin receptor substrate-1 (IRS-1) is regulated by both tyrosine and serine/threonine phosphorylation. Phosphorylation of some serine/threonine residues in IRS-1 dampens insulin signaling, whereas phosphorylation of other serine/threonine residues enhances insulin signaling. Phosphorylation of human IRS-1 at Ser629 was increased by insulin in Chinese hamster ovary cells expressing the insulin receptor (1.26 ± 0.09-fold; P < 0.05) and L6 cells (1.35 ± 0.29-fold; P < 0.05) expressinghuman IRS-1. Sequence analysis surrounding Ser629 revealed conformity to the consensus phosphorylation sequence recognized by Akt. Phosphorylation of IRS-1 at Ser629 in cells was decreased upon treatment with either an Akt inhibitor or by coexpression with kinase dead Akt, whereas Ser629 phosphorylation was increased by coexpression with constitutively active Akt. In addition, Ser629 of IRS-1 is directly phosphorylated by Akt in vitro. In cells, preventing phosphorylation of Ser 629 by a Ser629Ala mutation resulted in increased phosphorylation of Ser636, a known negative regulator of IRS-1, without affecting phosphorylation of Tyr632 or Ser616. Cells expressing the Ser629Ala mutation, along with increased Ser636 phosphorylation, had decreased insulin-stimulated association of the p85 regulatory subunit of phosphatidylinositol 3′-kinase with IRS-1 and decreased phosphorylation of Akt at Ser473. Finally, in vitro phosphorylation of a Ser629-containing IRS-1 fragment with Akt reduces the subsequent ability of ERK to phosphorylate Ser636/639. These results suggest that a feed-forward mechanism may exist whereby insulin activation of Akt leads to phosphorylation of IRS-1 at Ser629, resulting in decreased phosphorylation of IRS-1 at Ser636 and enhanced downstream signaling. Understanding the complex phosphorylation patterns of IRS-1 is crucial to elucidating the factors contributing to insulin resistance and, ultimately, the pathogenesis of type 2 diabetes.",
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