Bile acids enhance the activity of the insulin receptor and glycogen synthase in primary rodent hepatocytes

Hepatology. 2004 Feb;39(2):456-63. doi: 10.1002/hep.20043.

Abstract

Previously, we demonstrated that deoxycholic acid (DCA)-induced ERK1/2 and AKT signaling in primary hepatocytes is a protective response. In the present study, we examined the regulation of the phosphatidylinositol 3 (PI3) kinase/AKT/glycogen synthase (kinase) 3 (GSK3)/glycogen synthase (GS) pathway by bile acids. In primary hepatocytes, DCA activated ERBB1 (the epidermal growth factor receptor), ERBB2, and the insulin receptor, but not the insulin-like growth factor 1 (IGF-1) receptor. DCA-induced activation of the insulin receptor correlated with enhanced phosphorylation of insulin receptor substrate 1, effects that were both blocked by the insulin receptor inhibitor AG1024 and by expression of the dominant negative IGF-1 receptor (K1003R), which inhibited in trans. Expression of the dominant negative IGF-1 receptor (K1003R) also abolished DCA-induced AKT activation. Bile acid-induced activation of AKT and phosphorylation of GSK3 were blunted by the ERBB1 inhibitor AG1478 and abolished by AG1024. Bile acids caused activation of GS to a similar level induced by insulin (50 nM); both were blocked by inhibition of insulin receptor function and the PI3 kinase/AKT/GSK3 pathway. In conclusion, these findings suggest that bile acids and insulin may cooperate to regulate glucose storage in hepatocytes.

Publication types

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

MeSH terms

  • Adenoviridae / genetics
  • Animals
  • Bile Acids and Salts / pharmacology*
  • Cells, Cultured
  • Enzyme Activation / drug effects
  • Gene Expression Regulation, Enzymologic / drug effects
  • Genes, erbB-1 / physiology
  • Genes, erbB-2 / physiology
  • Genetic Vectors
  • Glucose / metabolism
  • Glycogen Synthase / genetics
  • Glycogen Synthase / metabolism*
  • Glycogen Synthase Kinase 3 / genetics
  • Glycogen Synthase Kinase 3 / metabolism*
  • Hepatocytes / cytology
  • Hepatocytes / drug effects
  • Hepatocytes / enzymology*
  • Male
  • Phosphatidylinositol 3-Kinases / metabolism
  • Protein-Serine-Threonine Kinases*
  • Proto-Oncogene Proteins / metabolism
  • Proto-Oncogene Proteins c-akt
  • Rats
  • Rats, Sprague-Dawley
  • Receptor, IGF Type 1 / genetics
  • Receptor, IGF Type 1 / metabolism*

Substances

  • Bile Acids and Salts
  • Proto-Oncogene Proteins
  • Glycogen Synthase
  • Phosphatidylinositol 3-Kinases
  • Receptor, IGF Type 1
  • Akt1 protein, rat
  • Protein-Serine-Threonine Kinases
  • Proto-Oncogene Proteins c-akt
  • Glycogen Synthase Kinase 3
  • Glucose