title: The function of the ATP-binding cassette (ABC) transporter ABCB1 is not susceptible to actin disruption.
abstract: Previously we have shown that the activity of the multidrug transporter ABCC1 (multidrug resistance protein 1), and its localization in lipid rafts, depends on cortical actin (Hummel I, Klappe K, Ercan C, Kok JW. Mol. Pharm. 2011 79, 229-40). Here we show that the efflux activity of the ATP-binding cassette (ABC) family member ABCB1 (P-glycoprotein), did not depend on actin, neither in ABCB1 over expressing murine National Institutes of Health (NIH) 3T3 MDR1 G185 cells nor in human SK-N-FI cells, which endogenously express ABCB1. Disruption of the actin cytoskeleton, upon treatment of the cells with latrunculin B or cytochalasin D, caused severe changes in cell and membrane morphology, and concomitant changes in the subcellular distribution of ABCB1, as revealed by confocal laser scanning and electron microscopy. Nevertheless, irrespective of actin perturbation, the cell surface pool of ABCB1 remained unaltered. In NIH 3T3 MDR1 G185 cells, ABCB1 is partly localized in detergent-free lipid rafts, which partitioned in two different density gradient regions, both enriched in cholesterol and sphingolipids. Interestingly, disruption of the actin cytoskeleton did not change the density gradient distribution of ABCB1. Our data demonstrate that the functioning of ABCB1 as an efflux pump does not depend on actin, which is due to its distribution in both cell surface-localized non-raft membrane areas and lipid raft domains, which do not depend on actin stabilization.
authors.affiliation: University Medical Center Groningen, University of Groningen, Department of Cell Biology, A. Deusinglaan 1, 9713 AV Groningen, The Netherlands.
authors.forename: Peter
authors.initials: P
authors.lastname: Meszaros
authors.forename: Ina
authors.initials: I
authors.lastname: Hummel
authors.forename: Karin
authors.initials: K
authors.lastname: Klappe
authors.forename: Oana
authors.initials: O
authors.lastname: Draghiciu
authors.forename: Dick
authors.initials: D
authors.lastname: Hoekstra
authors.forename: Jan W
authors.initials: JW
authors.lastname: Kok
mesh_terms: D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000737:chemistry*; D000199:Actins / Q000737:chemistry*; D000255:Adenosine Triphosphate / Q000737:chemistry*; D000818:Animals; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000494:pharmacology; D002784:Cholesterol / Q000737:chemistry; D015638:Cytochalasin D / Q000494:pharmacology; D003599:Cytoskeleton / Q000378:metabolism; D003902:Detergents / Q000494:pharmacology; D005786:Gene Expression Regulation; D006801:Humans; D021962:Membrane Microdomains / Q000737:chemistry; D051379:Mice; D018613:Microscopy, Confocal / Q000379:methods; D041681:NIH 3T3 Cells; D013107:Sphingolipids / Q000737:chemistry; D053778:Thiazolidines / Q000494:pharmacology
chemical_list: C513055:ABCB1 protein, human; D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000199:Actins; D019086:Bridged Bicyclo Compounds, Heterocyclic; D003902:Detergents; D013107:Sphingolipids; D053778:Thiazolidines; D015638:Cytochalasin D; D000255:Adenosine Triphosphate; D002784:Cholesterol; C507084:Abcb1b protein, mouse; C037068:latrunculin B