G protein-coupled receptor kinase 2 mediates endothelin-1-induced insulin resistance via the inhibition of both Galphaq/11 and insulin receptor substrate-1 pathways in 3T3-L1 adipocytes

Mol Endocrinol. 2005 Nov;19(11):2760-8. doi: 10.1210/me.2004-0429. Epub 2005 Jun 30.


G protein-coupled receptor kinases (GRKs) regulate seven-transmembrane receptors (7TMRs) by phosphorylating agonist-activated 7TMRs. Recently, we have reported that GRK2 can function as a negative regulator of insulin action by interfering with G protein-q/11 alpha-subunit (Galphaq/11) signaling, causing decreased glucose transporter 4 (GLUT4) translocation. We have also reported that chronic endothelin-1 (ET-1) treatment leads to heterologous desensitization of insulin signaling with decreased tyrosine phosphorylation of insulin receptor substrate (IRS)-1 and Galphaq/11, and decreased insulin-stimulated glucose transport in 3T3-L1 adipocytes. In the current study, we have investigated the role of GRK2 in chronic ET-1-induced insulin resistance. Insulin-induced GLUT4 translocation was inhibited by pretreatment with ET-1 for 24 h, and we found that this inhibitory effect was rescued by microinjection of anti-GRK2 antibody or GRK2 short interfering RNA. We further found that GRK2 mediates the inhibitory effects of ET-1 by two distinct mechanisms. Firstly, adenovirus-mediated overexpression of either wild-type (WT)- or kinase-deficient (KD)-GRK2 inhibited Galphaq/11 signaling, including tyrosine phosphorylation of Galphaq/11 and cdc42-associated phosphatidylinositol 3-kinase activity. Secondly, ET-1 treatment caused Ser/Thr phosphorylation of IRS-1 and IRS-1 protein degradation. Overexpression of KD-GRK2, but not WT-GRK2, inhibited ET-1-induced serine 612 phosphorylation of IRS-1 and restored activation of this pathway. Taken together, these results suggest that GRK2 mediates ET-1-induced insulin resistance by 1) inhibition of Galphaq/11 activation, and this effect is independent of GRK2 kinase activity, and 2) GRK2 kinase activity-mediated IRS-1 serine phosphorylation and degradation.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • 3T3-L1 Cells
  • Adipocytes / drug effects
  • Adipocytes / metabolism*
  • Animals
  • Antibodies / pharmacology
  • Endothelin-1 / metabolism
  • Endothelin-1 / pharmacology*
  • Endothelin-1 / toxicity
  • GTP-Binding Protein alpha Subunits, Gq-G11 / antagonists & inhibitors*
  • GTP-Binding Protein alpha Subunits, Gq-G11 / metabolism
  • Glucose Transporter Type 4 / metabolism
  • Insulin / pharmacology
  • Insulin Receptor Substrate Proteins
  • Insulin Resistance*
  • Mice
  • Mutation
  • Phosphoproteins / antagonists & inhibitors*
  • Phosphoproteins / metabolism
  • Phosphorylation
  • Protein Transport
  • Protein-Serine-Threonine Kinases / antagonists & inhibitors
  • Protein-Serine-Threonine Kinases / genetics
  • Protein-Serine-Threonine Kinases / metabolism*
  • RNA, Small Interfering / pharmacology
  • Serine / metabolism
  • Transcriptional Activation


  • Antibodies
  • Endothelin-1
  • Glucose Transporter Type 4
  • Insulin
  • Insulin Receptor Substrate Proteins
  • Irs1 protein, mouse
  • Phosphoproteins
  • RNA, Small Interfering
  • Serine
  • Protein-Serine-Threonine Kinases
  • GTP-Binding Protein alpha Subunits, Gq-G11