Cholesterol-regulated translocation of NPC1L1 to the cell surface facilitates free cholesterol uptake

J Biol Chem. 2006 Mar 10;281(10):6616-24. doi: 10.1074/jbc.M511123200. Epub 2005 Dec 30.

Abstract

Although NPC1L1 is required for intestinal cholesterol absorption, data demonstrating mechanisms by which this protein facilitates the process are few. In this study, a hepatoma cell line stably expressing human NPC1L1 was established, and cholesterol uptake was studied. A relationship between NPC1L1 intracellular trafficking and cholesterol uptake was apparent. At steady state, NPC1L1 proteins localized predominantly to the transferrin-positive endocytic recycling compartment, where free cholesterol also accumulated as revealed by filipin staining. Interestingly, acute cholesterol depletion induced with methyl-beta-cyclodextrin stimulated relocation of NPC1L1 to the plasma membrane, preferentially to a newly formed "apical-like" subdomain. This translocation was associated with a remarkable increase in cellular cholesterol uptake, which in turn was dose-dependently inhibited by ezetimibe, a novel cholesterol absorption inhibitor that specifically binds to NPC1L1. These findings define a cholesterol-regulated endocytic recycling of NPC1L1 as a novel mechanism regulating cellular cholesterol uptake.

Publication types

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

MeSH terms

  • Animals
  • Anticholesteremic Agents / pharmacology
  • Azetidines / pharmacology
  • Cell Line, Tumor
  • Cell Membrane / metabolism*
  • Cholesterol / chemistry*
  • Cholesterol / metabolism*
  • Endocytosis / physiology
  • Ezetimibe
  • Genes, Reporter
  • Golgi Apparatus / metabolism
  • Haplorhini
  • Humans
  • Liver / metabolism
  • Mannosyl-Glycoprotein Endo-beta-N-Acetylglucosaminidase / physiology
  • Membrane Proteins / antagonists & inhibitors
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism*
  • Membrane Transport Proteins
  • Protein Transport / physiology
  • Proteins / antagonists & inhibitors
  • Proteins / genetics
  • Proteins / metabolism*
  • Rats
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • Transferrin / metabolism

Substances

  • Anticholesteremic Agents
  • Azetidines
  • Membrane Proteins
  • Membrane Transport Proteins
  • NPC1L1 protein, human
  • Proteins
  • Recombinant Fusion Proteins
  • Transferrin
  • Cholesterol
  • Mannosyl-Glycoprotein Endo-beta-N-Acetylglucosaminidase
  • Ezetimibe