Hepatic nuclear factor 3- and hormone-regulated expression of the phosphoenolpyruvate carboxykinase and insulin-like growth factor-binding protein 1 genes

Mol Cell Biol. 1995 Mar;15(3):1747-58. doi: 10.1128/MCB.15.3.1747.

Abstract

The rate of transcription of the hepatic phosphoenolpyruvate carboxykinase (PEPCK) and insulin-like growth factor-binding protein 1 (IGFBP-1) genes is stimulated by glucocorticoids and inhibited by insulin. In both cases, the effect of insulin is dominant, since it suppresses both basal and glucocorticoid-stimulated PEPCK or IGFBP-1 gene transcription. Analyses of both promoters by transfection of PEPCK or IGFBP-1-chloramphenicol acetyltransferase fusion genes into rat hepatoma cells has led to the identification of insulin response sequences (IRSs) in both genes. The core IRS, T(G/A)TTTTG, is the same in both genes, but the PEPCK promoter has a single copy of this element whereas the IGFBP-1 promoter has two copies arranged as an inverted palindrome. The IGFBP-1 IRS and PEPCK IRS both bind the alpha and beta forms of hepatic nuclear factor 3 (HNF-3), although the latter does so with a sixfold-lower relative affinity. Both the PEPCK and the IGFBP-1 IRSs also function as accessory factor binding sites required for the full induction of gene transcription by glucocorticoids. A combination of transient transfection and DNA binding studies suggests that HNF-3 is the accessory factor that supports glucocorticoid-induced gene transcription. In both genes, the HNF-3 binding site overlaps the IRS core motif(s). A model in which insulin is postulated to mediate its negative effect on glucocorticoid-induced PEPCK and IGFBP-1 gene transcription indirectly by inhibiting HNF-3 action is proposed.

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

  • Animals
  • Base Sequence
  • Binding Sites
  • Carcinoma, Hepatocellular
  • Carrier Proteins / biosynthesis*
  • Cell Line
  • DNA / chemistry
  • DNA / metabolism
  • DNA-Binding Proteins / metabolism*
  • Dexamethasone / pharmacology*
  • Gene Expression Regulation* / drug effects
  • Hepatocyte Nuclear Factor 3-alpha
  • Hepatocyte Nuclear Factor 3-beta
  • Hepatocyte Nuclear Factor 3-gamma
  • Humans
  • Insulin / pharmacology*
  • Insulin-Like Growth Factor Binding Protein 1
  • Kinetics
  • Liver / metabolism*
  • Liver Neoplasms
  • Liver Neoplasms, Experimental
  • Molecular Sequence Data
  • Mutagenesis, Site-Directed
  • Nuclear Proteins / metabolism*
  • Oligodeoxyribonucleotides
  • Phosphoenolpyruvate Carboxykinase (GTP) / biosynthesis*
  • Promoter Regions, Genetic
  • Rats
  • Receptors, Glucocorticoid / biosynthesis
  • Receptors, Glucocorticoid / physiology
  • Recombinant Fusion Proteins / biosynthesis
  • Regulatory Sequences, Nucleic Acid
  • Transcription Factors / metabolism*
  • Transcription, Genetic
  • Transfection
  • Tumor Cells, Cultured

Substances

  • Carrier Proteins
  • DNA-Binding Proteins
  • FOXA1 protein, human
  • FOXA2 protein, human
  • FOXA3 protein, human
  • Foxa1 protein, rat
  • Foxa2 protein, rat
  • Foxa3 protein, rat
  • Hepatocyte Nuclear Factor 3-alpha
  • Insulin
  • Insulin-Like Growth Factor Binding Protein 1
  • Nuclear Proteins
  • Oligodeoxyribonucleotides
  • Receptors, Glucocorticoid
  • Recombinant Fusion Proteins
  • Transcription Factors
  • Hepatocyte Nuclear Factor 3-gamma
  • Hepatocyte Nuclear Factor 3-beta
  • Dexamethasone
  • DNA
  • Phosphoenolpyruvate Carboxykinase (GTP)