Identification and functional characterization of the peroxisomal proliferator response element in rat GLUT2 promoter

Diabetes. 2000 Sep;49(9):1517-24. doi: 10.2337/diabetes.49.9.1517.

Abstract

We identified the peroxisomal proliferator response element (PPRE) in the +68/+89 region of the rat GLUT2 gene. To identify whether the putative PPRE in the GLUT2 gene (GLUT2-PPRE) is functional, GLUT2 promoter-luciferase reporter constructs were transfected into CV-1 cells. Promoter activities were increased by coexpression of peroxisomal proliferator-activated receptor (PPAR)-gamma, retinoid X receptor (RXR)-alpha, and treatment of their ligands; troglitazone and 9-cis retinoic acid potentiated the transactivational effects. Introduction of mutations in GLUT2-PPRE resulted in loss of transactivational effects of the PPAR-gamma/RXR-alpha heterodimer. Electrophoretic mobility shift assay using nuclear extracts of CV-1 cells, which were transfected with various combinations of PPARs or RXR-alpha expression plasmids, revealed that heterodimers of PPAR-gamma and RXR-alpha preferentially bound to GLUT2-PPRE. In HIT-T15 cells, promoter activity of the rat GLUT2 gene was increased by troglitazone and 9-cis retinoic acid, and mutations of GLUT2-PPRE resulted in reduction of promoter activity. In addition, we observed increased GLUT2 transcription by troglitazone and 9-cis retinoic acid in isolated rat primary islets. These results suggested that the GLUT2-PPRE is functional and plays a significant role in gene expression of GLUT2 in pancreatic beta-cells. This is the first report identifying PPRE in a gene involved in glucose homeostasis, linking the effect of troglitazone on the regulation of insulin secretion.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alitretinoin
  • Animals
  • Base Sequence
  • Cell Line
  • Cells, Cultured
  • Chromans / pharmacology
  • Consensus Sequence
  • DNA-Binding Proteins / chemistry
  • DNA-Binding Proteins / metabolism
  • Dimerization
  • Gene Expression Regulation* / drug effects
  • Glucose Transporter Type 2
  • Hypoglycemic Agents / pharmacology
  • Islets of Langerhans / drug effects
  • Islets of Langerhans / metabolism*
  • Male
  • Monosaccharide Transport Proteins / genetics*
  • Promoter Regions, Genetic*
  • Protein Multimerization
  • Rats
  • Rats, Sprague-Dawley
  • Receptors, Cytoplasmic and Nuclear / chemistry
  • Receptors, Cytoplasmic and Nuclear / genetics
  • Receptors, Cytoplasmic and Nuclear / metabolism*
  • Receptors, Retinoic Acid / metabolism
  • Recombinant Fusion Proteins / biosynthesis
  • Recombinant Proteins / metabolism
  • Retinoid X Receptors
  • Sequence Alignment
  • Thiazoles / pharmacology
  • Thiazolidinediones*
  • Transcription Factors / chemistry
  • Transcription Factors / genetics
  • Transcription Factors / metabolism*
  • Transcription, Genetic / drug effects
  • Transfection
  • Tretinoin / pharmacology
  • Troglitazone

Substances

  • Chromans
  • DNA-Binding Proteins
  • Glucose Transporter Type 2
  • Hypoglycemic Agents
  • Monosaccharide Transport Proteins
  • Receptors, Cytoplasmic and Nuclear
  • Receptors, Retinoic Acid
  • Recombinant Fusion Proteins
  • Recombinant Proteins
  • Retinoid X Receptors
  • Thiazoles
  • Thiazolidinediones
  • Transcription Factors
  • Alitretinoin
  • Tretinoin
  • Troglitazone