AJP - GI Journal of Applied Physiology
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

Am J Physiol Gastrointest Liver Physiol 293: G1155-G1165, 2007. First published October 11, 2007; doi:10.1152/ajpgi.00334.2007
0193-1857/07 $8.00
This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow All Versions of this Article:
293/6/G1155    most recent
00334.2007v1
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Citing Articles
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Nguyen, H. T. T.
Right arrow Articles by Merlin, D.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Nguyen, H. T. T.
Right arrow Articles by Merlin, D.

MUCOSAL BIOLOGY

Association of PepT1 with lipid rafts differently modulates its transport activity in polarized and nonpolarized cells

Hang Thi Thu Nguyen,1 Laetitia Charrier-Hisamuddin,1 Guillaume Dalmasso,1 Abel Hiol,2 Shanthi Sitaraman,1 and Didier Merlin1

1Department of Medicine, Division of Digestive Diseases, Emory University School of Medicine, Atlanta, Georgia; and 2Université Paul Cezanne, Equipe Biochimie Alimentaire, Faculte des Sciences et Techniques, Marseille, France

Submitted 23 July 2007 ; accepted in final form 8 October 2007

The transporter PepT1, apically expressed in intestinal epithelial cells, is responsible for the uptake of di/tripeptides. PepT1 is also expressed in nonpolarized immune cells. Here we investigated the localization of PepT1 in lipid rafts in small intestinal brush border membranes (BBMs) and polarized and nonpolarized cells, as well as functional consequences of the association of PepT1 with lipid rafts. Immunoblot analysis showed the presence of PepT1 in low-density fractions isolated from mouse intestinal BBMs, polarized intestinal Caco2-BBE cells, and nonpolarized Jurkat cells by solubilization in ice-cold 0.5% Triton X-100 and sucrose gradient fractionation. PepT1 colocalized with lipid raft markers GM1 and N-aminopeptidase in intestinal BBMs and Caco2-BBE cell membranes. Disruption of lipid rafts with methyl-β-cyclodextrin (MβCD) shifted PepT1 from low- to high-density fractions. Remarkably, we found that MβCD treatment increased PepT1 transport activity in polarized intestinal epithelia but decreased that in intestinal BBM vesicles and nonpolarized immune cells. Mutational analysis showed that phenylalanine 293, phenylalanine 297, and threonine 281 in transmembrane segment 7 of the human di/tripeptide transporter, hPepT1, are important for the targeting to lipid rafts and transport activity of hPepT1. In conclusion, the association of PepT1 with lipid rafts differently modulates its transport activity in polarized and nonpolarized cells.

brush border; Caco2-BBE; mice


Address for reprint requests and other correspondence: D. Merlin, Emory Univ., Dept. of Medicine, Division of Digestive Diseases, 615 Michael St., Atlanta, GA 30322 (e-mail: dmerlin{at}emory.edu)






HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Visit Other APS Journals Online
Copyright © 2007 by the American Physiological Society.