Document Detail


Influence of class B scavenger receptors on cholesterol flux across the brush border membrane and intestinal absorption.
MedLine Citation:
PMID:  19454765     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
To learn more about how the step of cholesterol uptake into the brush border membrane (BBM) of enterocytes influences overall cholesterol absorption, we measured cholesterol absorption 4 and 24 h after administration of an intragastric bolus of radioactive cholesterol in mice with scavenger receptor class B, type 1 (SR-BI) and/or cluster determinant 36 (CD36) deleted. The cholesterol absorption efficiency is unaltered by deletion of either one or both of the receptors. In vitro determinations of the cholesterol uptake specific activity of the BBM from the mice reveal that the scavenger receptors facilitate cholesterol uptake into the proximal BBM. It follows that cholesterol uptake into the BBM is not normally rate-limiting for the cholesterol absorption process in vivo; a subsequent step, such as NPC1L1-mediated transfer from the BBM into the interior of the enterocyte, is rate-limiting. The absorption of dietary cholesterol after 4 h in mice lacking SR-BI and/or CD36 and fed a high-fat/high-cholesterol diet is delayed to more distal regions of the small intestine. This effect probably arises because ATP binding cassette half transporters G5 and G8-mediated back flux of cholesterol from the BBM to the lumen of the small intestine limits absorption and causes the local cholesterol uptake facilitated by SR-BI and CD36 to become rate-limiting under this dietary condition.
Authors:
David V Nguyen; Victor A Drover; Martin Knopfel; Padmaja Dhanasekaran; Helmut Hauser; Michael C Phillips
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural     Date:  2009-05-19
Journal Detail:
Title:  Journal of lipid research     Volume:  50     ISSN:  0022-2275     ISO Abbreviation:  J. Lipid Res.     Publication Date:  2009 Nov 
Date Detail:
Created Date:  2009-12-07     Completed Date:  2010-03-16     Revised Date:  2010-11-02    
Medline Journal Info:
Nlm Unique ID:  0376606     Medline TA:  J Lipid Res     Country:  United States    
Other Details:
Languages:  eng     Pagination:  2235-44     Citation Subset:  IM    
Affiliation:
Gastroenterology, Hepatology, and Nutrition Division, Children's Hospital of Philadelphia and University of Pennsylvania School of Medicine, Philadelphia, PA 19104-4318, USA.
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MeSH Terms
Descriptor/Qualifier:
ATP-Binding Cassette Transporters / genetics
Animals
Antigens, CD36 / genetics,  metabolism
Biological Transport
Carbon Radioisotopes
Cholesterol / metabolism*
Enterocytes / cytology,  metabolism
Gene Expression
Intestinal Absorption*
Intestine, Small / cytology,  metabolism
Lipoproteins / genetics
Membrane Transport Proteins / genetics
Mice
Mice, Inbred C57BL
Mice, Knockout
Microvilli / metabolism*
Reverse Transcriptase Polymerase Chain Reaction
Scavenger Receptors, Class B / genetics,  metabolism*
Grant Support
ID/Acronym/Agency:
HL-22633/HL/NHLBI NIH HHS
Chemical
Reg. No./Substance:
0/ABCG5 protein, mouse; 0/ATP-Binding Cassette Transporters; 0/Antigens, CD36; 0/Carbon Radioisotopes; 0/Lipoproteins; 0/Membrane Transport Proteins; 0/Npc1l1 protein, mouse; 0/Scarb1 protein, mouse; 0/Scavenger Receptors, Class B; 57-88-5/Cholesterol

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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