Up-regulation of low-density lipoprotein receptor in human hepatocytes is induced by sequestration of free cholesterol in the endosomal/lysosomal compartment

Biochem Pharmacol. 2004 Jun 15;67(12):2281-9. doi: 10.1016/j.bcp.2004.03.006.

Abstract

Up-regulation of low-density lipoprotein receptor (LDLr) is a key mechanism to control elevated plasma LDL-cholesterol levels. In the present paper, we compare the ability of four distinct pharmacological drugs to up-regulate LDLr expression in human hepatocytes. HepG2 cells were treated with the steroidal analog GW707, the oxidosqualene cyclase inhibitor U18666A, the 3beta-hydroxysterol Delta(7)-reductase inhibitor AY-9944 and the vacuolar-type ATPase inhibitor bafilomycin A1. We found that the four compounds induced sequestration of free cholesterol in the endosomal/lysosomal compartment leading to a positive filipin staining pattern and a complete inhibition of cholesteryl ester synthesis. As a consequence of the sequestration of cholesterol, the expression and the activity of LDLr were strongly induced resulting from a transcriptional effect which was measured by a reporter gene assay. These effects were fully abolished when an exogenous water soluble cholesterol analog was added to the cells. These findings have led to the identification of a common mechanism to up-regulate LDLr expression in human hepatocytes and may represent an interesting alternative approach to identify new hypolipidemic drugs.

MeSH terms

  • Androstenes / pharmacology
  • Anticholesteremic Agents / pharmacology
  • Cholesterol / biosynthesis
  • Cholesterol / metabolism*
  • Endosomes / drug effects
  • Endosomes / metabolism*
  • Gene Expression / drug effects
  • Hepatocytes / drug effects
  • Hepatocytes / metabolism*
  • Humans
  • Lysosomes / drug effects
  • Lysosomes / metabolism*
  • Macrolides / pharmacology
  • Receptors, LDL / biosynthesis*
  • Steroids / pharmacology
  • Tumor Cells, Cultured
  • Up-Regulation
  • trans-1,4-Bis(2-chlorobenzaminomethyl)cyclohexane Dihydrochloride / pharmacology

Substances

  • Androstenes
  • Anticholesteremic Agents
  • GW 707
  • Macrolides
  • Receptors, LDL
  • Steroids
  • 3-beta-(2-(diethylamino)ethoxy)androst-5-en-17-one
  • trans-1,4-Bis(2-chlorobenzaminomethyl)cyclohexane Dihydrochloride
  • bafilomycin A1
  • Cholesterol