Insulin/IGF-1 and TNF-alpha stimulate phosphorylation of IRS-1 at inhibitory Ser307 via distinct pathways

J Clin Invest. 2001 Jan;107(2):181-9. doi: 10.1172/JCI10934.

Abstract

Serine/threonine phosphorylation of IRS-1 might inhibit insulin signaling, but the relevant phosphorylation sites are difficult to identify in cultured cells and to validate in isolated tissues. Recently, we discovered that recombinant NH2-terminal Jun kinase phosphorylates IRS-1 at Ser307, which inhibits insulin-stimulated tyrosine phosphorylation of IRS-1. To monitor phosphorylation of Ser307 in various cell and tissue backgrounds, we prepared a phosphospecific polyclonal antibody designated alphapSer307. This antibody revealed that TNF-alpha, IGF-1, or insulin stimulated phosphorylation of IRS-1 at Ser307 in 3T3-L1 preadipocytes and adipocytes. Insulin injected into mice or rats also stimulated phosphorylation of Ser307 on IRS-1 immunoprecipitated from muscle; moreover, Ser307 was phosphorylated in human muscle during the hyperinsulinemic euglycemic clamp. Experiments in 3T3-L1 preadipocytes and adipocytes revealed that insulin-stimulated phosphorylation of Ser307 was inhibited by LY294002 or wortmannin, whereas TNF-alpha-stimulated phosphorylation was inhibited by PD98059. Thus, distinct kinase pathways might converge at Ser307 to mediate feedback or heterologous inhibition of IRS-1 signaling to counterregulate the insulin response.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Anisomycin / pharmacology
  • CHO Cells
  • Cricetinae
  • Insulin / pharmacology*
  • Insulin Antagonists / pharmacokinetics
  • Insulin Resistance
  • Insulin-Like Growth Factor I / pharmacology*
  • MAP Kinase Kinase 1
  • Mitogen-Activated Protein Kinase Kinases / metabolism
  • Phosphatidylinositol 3-Kinases / metabolism
  • Phosphorylation / drug effects
  • Protein-Serine-Threonine Kinases / chemistry*
  • Protein-Serine-Threonine Kinases / metabolism
  • Receptor, Insulin
  • Serine / chemistry
  • Signal Transduction
  • Tumor Necrosis Factor-alpha / pharmacology*
  • Tyrosine / chemistry

Substances

  • Insulin
  • Insulin Antagonists
  • Tumor Necrosis Factor-alpha
  • Tyrosine
  • Serine
  • Insulin-Like Growth Factor I
  • Anisomycin
  • Phosphatidylinositol 3-Kinases
  • Receptor, Insulin
  • Protein-Serine-Threonine Kinases
  • insulin receptor serine kinase
  • MAP Kinase Kinase 1
  • MAP2K1 protein, human
  • Mitogen-Activated Protein Kinase Kinases