title: Long term myriocin treatment increases MRP1 transport activity.
abstract: We investigated the effect of myriocin treatment, which extensively depletes sphingolipids from cells, on multidrug resistance-related protein 1 (MRP1) efflux activity in MRP1 expressing cells and isolated plasma membrane vesicles. Our data reveal that both short term (3 days) and long term (7 days) treatment effectively reduce the cellular sphingolipid content to the same level. Intriguingly, a two-fold increase in MRP1-mediated efflux activity was observed following long term treatment, while short term treatment had no impact. Very similar data were obtained with plasma membrane vesicles isolated from myriocin-treated cells. Exploiting the cell-free vesicle system, Michaelis-Menten analysis revealed that the intrinsic MRP1 activity remained unaltered; however, the fraction of active transporter molecules increased. We demonstrate that the latter effect is due to an enhanced recruitment of MRP1 into lipid raft fractions, thereby promoting MRP1 activity.
authors.affiliation: Department of Cell Biology, University Medical Center Groningen, University of Groningen, A. Deusinglaan 1, 9713 AV Groningen, The Netherlands.
authors.forename: Peter
authors.initials: P
authors.lastname: Meszaros
authors.forename: Karin
authors.initials: K
authors.lastname: Klappe
authors.forename: Annie
authors.initials: A
authors.lastname: van Dam
authors.forename: Pavlina T
authors.initials: PT
authors.lastname: Ivanova
authors.forename: Stephen B
authors.initials: SB
authors.lastname: Milne
authors.forename: David S
authors.initials: DS
authors.lastname: Myers
authors.forename: H Alex
authors.initials: HA
authors.lastname: Brown
authors.forename: Hjalmar
authors.initials: H
authors.lastname: Permentier
authors.forename: Dick
authors.initials: D
authors.lastname: Hoekstra
authors.forename: Jan W
authors.initials: JW
authors.lastname: Kok
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism; D000818:Animals; D022461:Caveolins / Q000378:metabolism; D006224:Cricetinae; D005229:Fatty Acids, Monounsaturated / Q000494:pharmacology*; D006801:Humans; D007700:Kinetics; D017997:Leukotriene C4 / Q000378:metabolism; D021962:Membrane Microdomains / Q000187:drug effects / Q000378:metabolism; D051379:Mice; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000378:metabolism*; D041681:NIH 3T3 Cells; D010718:Phosphatidylserines / Q000378:metabolism; D021381:Protein Transport; D013107:Sphingolipids / Q000378:metabolism
chemical_list: D000251:Adenosine Triphosphatases; D022461:Caveolins; D005229:Fatty Acids, Monounsaturated; D017997:Leukotriene C4; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D010718:Phosphatidylserines; D013107:Sphingolipids; C421109:multidrug resistance-associated protein 1; C001996:thermozymocidin