Regulation of expression of citrate synthase by the retinoic acid receptor-related orphan receptor α (RORα)

PLoS One. 2012;7(4):e33804. doi: 10.1371/journal.pone.0033804. Epub 2012 Apr 2.

Abstract

The retinoic acid receptor-related orphan receptor α (RORα) is a member of the nuclear receptor superfamily of transcription factors that plays an important role in regulation of the circadian rhythm and metabolism. Mice lacking a functional RORα display a range of metabolic abnormalities including decreased serum cholesterol and plasma triglycerides. Citrate synthase (CS) is a key enzyme of the citric acid cycle that provides energy for cellular function. Additionally, CS plays a critical role in providing citrate derived acetyl-CoA for lipogenesis and cholesterologenesis. Here, we identified a functional RORα response element (RORE) in the promoter of the CS gene. ChIP analysis demonstrates RORα occupancy of the CS promoter and a putative RORE binds to RORα effectively in an electrophoretic mobility shift assay and confers RORα responsiveness to a reporter gene in a cotransfection assay. We also observed a decrease in CS gene expression and CS enzymatic activity in the staggerer mouse, which has a mutation of in the Rora gene resulting in nonfunctional RORα protein. Furthermore, we found that SR1001 a RORα inverse agonist eliminated the circadian pattern of expression of CS mRNA in mice. These data suggest that CS is a direct RORα target gene and one mechanism by which RORα regulates lipid metabolism is via regulation of CS expression.

Publication types

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

MeSH terms

  • Animals
  • Base Sequence
  • Binding Sites
  • Citrate (si)-Synthase / genetics*
  • Citrate (si)-Synthase / metabolism
  • Gene Expression Regulation, Enzymologic*
  • Hep G2 Cells
  • Humans
  • Liver / enzymology
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Mice, Neurologic Mutants
  • Nuclear Receptor Subfamily 1, Group F, Member 1 / metabolism
  • Nuclear Receptor Subfamily 1, Group F, Member 1 / physiology*
  • Promoter Regions, Genetic
  • Protein Binding
  • Transcription, Genetic

Substances

  • Nuclear Receptor Subfamily 1, Group F, Member 1
  • RORA protein, human
  • Citrate (si)-Synthase