P-glycoprotein in blood-brain barrier endothelial cells: interaction and oligomerization with caveolins.
P-glycoprotein (P-gp), an adenosine triphosphate (ATP)-binding cassette transporter which acts as a drug efflux pump, is highly expressed at the blood-brain barrier (BBB) where it plays an important role in brain protection. Recently, P-gp has been reported to be located in the caveolae of multidrug-resistant cells. In this study, we investigated the localization and the activity of P-gp in the caveolae of endothelial cells of the BBB. We used an in vitro model of the BBB which is formed by co-culture of bovine brain capillary endothelial cells (BBCEC) with astrocytes. Caveolar microdomains isolated from BBCEC are enriched in P-gp, cholesterol, caveolin-1, and caveolin-2. Moreover, P-gp interacts with caveolin-1 and caveolin-2; together, they form a high molecular mass complex. P-gp in isolated caveolae is able to bind its substrates, and the caveolae-disrupting agents filipin III and nystatin decrease P-gp transport activity. In addition, mutations in the caveolin-binding motif present in P-gp reduced the interaction of P-gp with caveolin-1 and increased the transport activity of P-gp. Thus, P-gp expressed at the BBB is mainly localized in caveolae and its activity may be modulated by interaction with caveolin-1.
Jodoin
Julie
J
Laboratoire de médecine moléculaire, Centre de cancérologie Charles Bruneau, Université du Québec á Montréal, Hôpital Sainte-Justine, Montréal, Québec, Canada.
Demeule
Michel
M
Fenart
Laurence
L
Cecchelli
Roméo
R
Farmer
Sarah
S
Linton
Kenneth J
KJ
Higgins
Christopher F
CF
Béliveau
Richard
R
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D001253:Astrocytes / Q000166:cytology / Q000378:metabolism*; D001665:Binding Sites / Q000235:genetics / Q000502:physiology; D001812:Blood-Brain Barrier / Q000378:metabolism*; D001921:Brain / Q000098:blood supply; D002196:Capillaries / Q000166:cytology; D002417:Cattle; D021941:Caveolae / Q000737:chemistry / Q000378:metabolism; D051242:Caveolin 1; D051243:Caveolin 2; D022461:Caveolins / Q000378:metabolism*; D002478:Cells, Cultured; D018920:Coculture Techniques; D004285:Dogs; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism*; D007668:Kidney / Q000166:cytology / Q000378:metabolism; D046911:Macromolecular Substances; D008954:Models, Biological; D016297:Mutagenesis, Site-Directed; D011485:Protein Binding / Q000502:physiology; D021381:Protein Transport / Q000502:physiology; D051381:Rats
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; C495537:Cav1 protein, rat; D051242:Caveolin 1; D051243:Caveolin 2; D022461:Caveolins; D046911:Macromolecular Substances