Expression of various multidrug resistance-associated protein (MRP) homologues in brain microvessel endothelial cells.
Multidrug resistance-associated protein (MRP) actively transports a broad range of anionic compounds out of the cell. To date, six different homologues of MRP (i.e. MRP1-MRP6) have been identified. The current study examines the expression of the various MRP homologues in both primary cultured bovine brain microvessel endothelial cells (BBMEC) and the capillary-enriched fraction from bovine brain homogenates. RT-PCR analysis demonstrated the presence of MRP1, MRP4, MRP5 and MRP6 in both BBMEC and the capillary-enriched fractions of brain homogenates. While low levels of MRP3 were detected in the BBMEC, it was not observed in the capillary-enriched fraction. In addition, RT-PCR and Western blot studies indicated an absence of MRP2 expression in both blood-brain barrier preparations. The presence of several different MRP homologues in the brain microvessel endothelial cells may be important in controlling the permeability of the blood-brain barrier to organic anions.
Zhang
Y
Y
Department of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska, 986025 Nebraska Medical Center, Omaha, NE 68198-6025, USA.
Han
H
H
Elmquist
W F
WF
Miller
D W
DW
D018528:ATP-Binding Cassette Transporters / Q000378:metabolism*; D000818:Animals; D002417:Cattle; D002478:Cells, Cultured; D002560:Cerebrovascular Circulation / Q000502:physiology*; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism*; D006801:Humans; D006822:Hybrid Cells; D008833:Microcirculation / Q000502:physiology; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D020033:Protein Isoforms / Q000378:metabolism; D051381:Rats; D014407:Tumor Cells, Cultured
D018528:ATP-Binding Cassette Transporters; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D020033:Protein Isoforms