Related Experiment Videos

Regulation of cholesterologenesis by the oxysterol receptor, LXRalpha

Yongjun Wang1, Pamela M Rogers, Chen Su

  • 1Nuclear Receptor Biology Laboratory, Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, Louisiana 70808, USA.

The Journal of Biological Chemistry
|August 5, 2008
PubMed

Insights

Liver X receptor alpha (LXRalpha) regulates cholesterol biosynthesis by directly silencing key enzymes. Novel negative LXR DNA response elements (nLXREs) mediate this oxysterol-dependent repression, impacting cholesterol metabolism.

Area of Science:

  • Biochemistry
  • Molecular Biology
  • Cellular Biology

Background:

  • Cholesterol is vital for cellular function, but its dysregulation contributes to diseases like atherosclerosis.
  • Cholesterol biosynthesis is tightly controlled by feedback mechanisms involving sterols and oxysterols.
  • Sterol regulatory element-binding protein-2 (SREBP-2) mediates transcriptional responses to lipids in cholesterol metabolism.

Purpose of the Study:

  • To investigate the role of liver X receptor alpha (LXRalpha) in regulating cholesterol biosynthesis.
  • To identify the specific mechanisms by which LXRalpha controls cholesterologenic enzymes.

Main Methods:

  • Analysis of gene expression regulation by LXRalpha.
  • Identification of novel negative LXR DNA response elements (nLXREs) in target genes.
  • Examination of the interplay between SRE and nLXRE in gene repression.

Main Results:

  • LXRalpha directly silences the expression of lanosterol 14alpha-demethylase (CYP51A1) and squalene synthase.
  • Novel nLXREs in the CYP51A1 and squalene synthase genes mediate LXRalpha-dependent repression.
  • Both SRE and nLXRE are crucial for oxysterol-mediated repression of CYP51A1.

Conclusions:

  • LXRalpha plays a significant role in regulating cholesterol biosynthesis.
  • The identification of nLXREs provides new insights into the molecular mechanisms of cholesterol metabolism control.
  • These findings contribute to understanding how LXRalpha influences cellular cholesterol homeostasis.

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