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PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
2005-1-11
pubmed:abstractText
Intestinal cholesterol absorption is an important regulator of serum cholesterol levels. Ezetimibe is a specific inhibitor of intestinal cholesterol absorption recently introduced into medical practice; its mechanism of action, however, is still unknown. Ezetimibe neither influences the release of cholesterol from mixed micelles in the gut lumen nor the transfer of cholesterol to the enterocyte brush border membrane. With membrane-impermeable Ezetimibe analogues we could demonstrate that binding of cholesterol absorption inhibitors to the brush border membrane of small intestinal enterocytes from the gut lumen is sufficient for inhibition of cholesterol absorption. A 145-kDa integral membrane protein was identified as the molecular target for cholesterol absorption inhibitors in the enterocyte brush border membrane by photoaffinity labeling with photoreactive Ezetimibe analogues (Kramer, W., Glombik, H., Petry, S., Heuer, H., Schafer, H. L., Wendler, W., Corsiero, D., Girbig, F., and Weyland, C. (2000) FEBS Lett. 487, 293-297). The 145-kDa Ezetimibe-binding protein was purified by three different methods and sequencing revealed its identity with the membrane-bound ectoenzyme aminopeptidase N ((alanyl)aminopeptidase; EC 3.4.11.2; APN; leukemia antigen CD13). The enzymatic activity of APN was not influenced by Ezetimibe (analogues). The uptake of cholesterol delivered by mixed micelles by confluent CaCo-2 cells was partially inhibited by Ezetimibe and nonabsorbable Ezetimibe analogues. Preincubation of confluent CaCo-2 cells with Ezetimibe led to a strong decrease of fluorescent APN staining with a monoclonal antibody in the plasma membrane. Independent on its enzymatic activity, aminopeptidase N is involved in endocytotic processes like the uptake of viruses. Our findings suggest that binding of Ezetimibe to APN from the lumen of the small intestine blocks endocytosis of cholesterol-rich membrane microdomains, thereby limiting intestinal cholesterol absorption.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jan
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
14
pubmed:volume
280
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1306-20
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed-meshheading:15494415-Absorption, pubmed-meshheading:15494415-Animals, pubmed-meshheading:15494415-Anticholesteremic Agents, pubmed-meshheading:15494415-Antigens, CD13, pubmed-meshheading:15494415-Azetidines, pubmed-meshheading:15494415-Caco-2 Cells, pubmed-meshheading:15494415-Carrier Proteins, pubmed-meshheading:15494415-Cell Membrane, pubmed-meshheading:15494415-Cholesterol, pubmed-meshheading:15494415-Chromatography, Affinity, pubmed-meshheading:15494415-Colon, pubmed-meshheading:15494415-Enterocytes, pubmed-meshheading:15494415-Glycoside Hydrolases, pubmed-meshheading:15494415-Glycosylation, pubmed-meshheading:15494415-Humans, pubmed-meshheading:15494415-Intestine, Small, pubmed-meshheading:15494415-Kidney, pubmed-meshheading:15494415-Micelles, pubmed-meshheading:15494415-Microvilli, pubmed-meshheading:15494415-Molecular Weight, pubmed-meshheading:15494415-Photoaffinity Labels, pubmed-meshheading:15494415-Protein Binding, pubmed-meshheading:15494415-Rabbits, pubmed-meshheading:15494415-Spectrometry, Mass, Electrospray Ionization, pubmed-meshheading:15494415-Stomach
pubmed:year
2005
pubmed:articleTitle
Aminopeptidase N (CD13) is a molecular target of the cholesterol absorption inhibitor ezetimibe in the enterocyte brush border membrane.
pubmed:affiliation
Aventis Pharma Deutschland GmbH, ein Unternehmen der sanofi-aventis-Gruppe, D-65926 Frankfurt am Main, Germany. Werner.Kramer@aventis.com
pubmed:publicationType
Journal Article