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Journal of Lipid Research, Vol. 48, 1735-1745, August 2007
Copyright © 2007 by American Society for Biochemistry and Molecular Biology

Ezetimibe interferes with cholesterol trafficking from the plasma membrane to the endoplasmic reticulum in CaCo-2 cells

F. Jeffrey Field¹, Kim Watt and Satya N. Mathur

Department of Internal Medicine, University of Iowa, Iowa City, IA 52242

Published, JLR Papers in Press, May 1, 2007.

¹ To whom correspondence should be addressed. e-mail: f-jeffrey-field{at}uiowa.edu

Niemann-Pick C1-like 1 protein (NPC1L1) is the putative intestinal sterol transporter and the molecular target of ezetimibe, a potent inhibitor of cholesterol absorption. To address the role of NPC1L1 in cholesterol trafficking in intestine, the regulation of cholesterol trafficking by ezetimibe was studied in the human intestinal cell line, CaCo-2. Ezetimibe caused only a modest decrease in the uptake of micellar cholesterol, but markedly prevented its esterification. Cholesterol trafficking from the plasma membrane to the endoplasmic reticulum was profoundly disrupted by ezetimibe without altering the trafficking of cholesterol from the endoplasmic reticulum to the plasma membrane. Cholesterol oxidase-accessible cholesterol at the apical membrane was increased by ezetimibe. Cholesterol synthesis was modestly increased. Although the amount of cholesteryl esters secreted at the basolateral membrane was markedly decreased by ezetimibe, the transport of lipids and the number of lipoprotein particles secreted were not altered. NPC1L1 gene and protein expression were decreased by sterol influx, whereas cholesterol depletion enhanced NPC1L1 gene and protein expression. These results suggest that NPC1L1 plays a role in cholesterol uptake and cholesterol trafficking from the plasma membrane to the endoplasmic reticulum. Interfering with its function will profoundly decrease the amount of cholesterol transported into lymph.

Supplementary key words Niemann-Pick type C1 • Niemann-Pick C1-like 1 • lipoproteins

Abbreviations: ABC, ATP-binding cassette; apoB, apolipoprotein B; BB, brush-border membranes; DMEM, Dulbecco's Modified Eagle's Medium; LDH, lactate dehydrogenase; NBBM, nonbrush-border membranes; NPC1, Niemann-Pick type C1; NPC1L1, Niemann-Pick C1-like 1 protein

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