title: Cholesterol-regulated translocation of NPC1L1 to the cell surface facilitates free cholesterol uptake.
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.
authors.affiliation: Department of Pathology, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27157-1040, USA. lyu@wfubmc.edu
authors.forename: Liqing
authors.initials: L
authors.lastname: Yu
authors.forename: Shantaram
authors.initials: S
authors.lastname: Bharadwaj
authors.forename: J Mark
authors.initials: JM
authors.lastname: Brown
authors.forename: Yinyan
authors.initials: Y
authors.lastname: Ma
authors.forename: Wei
authors.initials: W
authors.lastname: Du
authors.forename: Matthew A
authors.initials: MA
authors.lastname: Davis
authors.forename: Peter
authors.initials: P
authors.lastname: Michaely
authors.forename: Pingsheng
authors.initials: P
authors.lastname: Liu
authors.forename: Mark C
authors.initials: MC
authors.lastname: Willingham
authors.forename: Lawrence L
authors.initials: LL
authors.lastname: Rudel
mesh_terms: D000818:Animals; D000924:Anticholesteremic Agents / Q000494:pharmacology; D001384:Azetidines / Q000494:pharmacology; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000378:metabolism*; D002784:Cholesterol / Q000737:chemistry* / Q000378:metabolism*; D004705:Endocytosis / Q000502:physiology; D000069438:Ezetimibe; D017930:Genes, Reporter; D006056:Golgi Apparatus / Q000378:metabolism; D000882:Haplorhini; D006801:Humans; D008099:Liver / Q000378:metabolism; D017038:Mannosyl-Glycoprotein Endo-beta-N-Acetylglucosaminidase / Q000502:physiology; D008565:Membrane Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D026901:Membrane Transport Proteins; D021381:Protein Transport / Q000502:physiology; D011506:Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D014168:Transferrin / Q000378:metabolism
chemical_list: D000924:Anticholesteremic Agents; D001384:Azetidines; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; C410800:NPC1L1 protein, human; D011506:Proteins; D011993:Recombinant Fusion Proteins; D014168:Transferrin; D002784:Cholesterol; D017038:Mannosyl-Glycoprotein Endo-beta-N-Acetylglucosaminidase; D000069438:Ezetimibe