Liver X receptor α is involved in the transcriptional regulation of the 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase gene

Diabetes. 2012 May;61(5):1062-71. doi: 10.2337/db11-1255. Epub 2012 Mar 13.

Abstract

The activity of 6-phosphofructo-1-kinase is strictly controlled by fructose-2,6-bisphosphate, the level of which is regulated by another enzyme, 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase (PFK2/FBP2). PFK2/FBP2 is a bifunctional enzyme, having kinase and phosphatase activities, and regulates both glycolysis and gluconeogenesis. Here, we examined the hormonal regulation of the PFK2/FBP2 gene in vitro using the reporter assay, the electromobility shift assay (EMSA), and the chromatin immunoprecipitation (ChIP) assay in HuH7 cells and also using the mouse liver in vivo. We found that the transcriptional activity of the PFK2/FBP2 gene was stimulated by insulin and inhibited by cAMP and glucocorticoid. Liver X receptor (LXR) α showed a potent and specific stimulatory effect on PFK2/FBP2 gene transcription. Deletion and mutagenesis analyses identified the LXR response element (LXRE) in the 5'-promoter region of the PFK2/FBP2 gene. Binding of LXRα was confirmed by the EMSA and ChIP assay. Endogenous PFK2/FBP2 mRNA in the mouse liver was increased in the fasting/refeeding state compared with the fasting state. Altogether, PFK2/FBP2 gene transcription is found to be regulated in a way that is more similar to other glycolytic enzyme genes than to gluconeogenic genes. Furthermore, our data strongly suggest that LXRα is one of the key regulators of PFK2/FBP2 gene transcription.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Ascorbic Acid
  • Base Sequence
  • Cell Line
  • Cholecalciferol
  • Colforsin / administration & dosage
  • Colforsin / pharmacology
  • Dehydroepiandrosterone / analogs & derivatives
  • Dexamethasone / administration & dosage
  • Dexamethasone / pharmacology
  • Food Deprivation
  • Gene Expression Regulation / drug effects
  • Gene Expression Regulation / physiology
  • Glucose / pharmacology
  • Hepatocytes / drug effects
  • Hepatocytes / metabolism
  • Humans
  • Hydrocarbons, Fluorinated / pharmacology
  • Insulin / administration & dosage
  • Insulin / pharmacology
  • Liver / drug effects
  • Liver / metabolism
  • Liver X Receptors
  • Mice
  • Mice, Inbred C57BL
  • Mutation
  • Nicotinic Acids
  • Orphan Nuclear Receptors / agonists
  • Orphan Nuclear Receptors / genetics
  • Orphan Nuclear Receptors / metabolism*
  • Phosphofructokinase-2 / genetics*
  • Phosphofructokinase-2 / metabolism
  • Plant Extracts
  • Real-Time Polymerase Chain Reaction
  • Reverse Transcriptase Polymerase Chain Reaction
  • Sulfonamides / pharmacology

Substances

  • HUM 5007
  • Hydrocarbons, Fluorinated
  • Insulin
  • Liver X Receptors
  • NR1H3 protein, human
  • Nicotinic Acids
  • Nr1h3 protein, mouse
  • Orphan Nuclear Receptors
  • Plant Extracts
  • Sulfonamides
  • TO-901317
  • Cholecalciferol
  • Colforsin
  • Dehydroepiandrosterone
  • Dexamethasone
  • Phosphofructokinase-2
  • Glucose
  • Ascorbic Acid