title: Activation of beta-catenin signalling by GSK-3 inhibition increases p-glycoprotein expression in brain endothelial cells.
abstract: This study investigates involvement of beta-catenin signalling in regulation of p-glycoprotein (p-gp) expression in endothelial cells derived from brain vasculature. Pharmacological interventions that enhance or that block beta-catenin signalling were applied to primary rat brain endothelial cells and to immortalized human brain endothelial cells, hCMEC/D3, nuclear translocation of beta-catenin being determined by immunocytochemistry and by western blot analysis to confirm effectiveness of the manipulations. Using the specific glycogen synthase kinase-3 (GSK-3) inhibitor 6-bromoindirubin-3'-oxime enhanced beta-catenin and increased p-gp expression including activating the MDR1 promoter. These increases were accompanied by increases in p-gp-mediated efflux capability as observed from alterations in intracellular fluorescent calcein accumulation detected by flow cytometry. Similar increases in p-gp expression were noted with other GSK-3 inhibitors, i.e. 1-azakenpaullone or LiCl. Application of Wnt agonist [2-amino-4-(3,4-(methylenedioxy) benzylamino)-6-(3-methoxyphenyl)pyrimidine] also enhanced beta-catenin and increased transcript and protein levels of p-gp. By contrast, down-regulating the pathway using Dickkopf-1 or quercetin decreased p-gp expression. Similar changes were observed with multidrug resistance protein 4 and breast cancer resistance protein, both known to be present at the blood-brain barrier. These results suggest that regulation of p-gp and other multidrug efflux transporters in brain vasculature can be influenced by beta-catenin signalling.
authors.affiliation: Department of Pharmacology, University of Cambridge, Cambridge, UK.
authors.forename: Joseph C
authors.initials: JC
authors.lastname: Lim
authors.forename: Katarzyna D
authors.initials: KD
authors.lastname: Kania
authors.forename: Hasini
authors.initials: H
authors.lastname: Wijesuriya
authors.forename: Sangeeta
authors.initials: S
authors.lastname: Chawla
authors.forename: Jaswinder K
authors.initials: JK
authors.lastname: Sethi
authors.forename: Lukasz
authors.initials: L
authors.lastname: Pulaski
authors.forename: Ignacio A
authors.initials: IA
authors.lastname: Romero
authors.forename: Pierre O
authors.initials: PO
authors.lastname: Couraud
authors.forename: Babette B
authors.initials: BB
authors.lastname: Weksler
authors.forename: Stephen B
authors.initials: SB
authors.lastname: Hladky
authors.forename: Margery A
authors.initials: MA
authors.lastname: Barrand
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000096:biosynthesis* / Q000235:genetics; D000818:Animals; D001812:Blood-Brain Barrier / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D001921:Brain / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D002461:Cell Line, Transformed; D002478:Cells, Cultured; D015536:Down-Regulation / Q000187:drug effects / Q000502:physiology; D042783:Endothelial Cells / Q000166:cytology / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology*; D038362:Glycogen Synthase Kinase 3 / Q000037:antagonists & inhibitors* / Q000378:metabolism; D000071679:Glycogen Synthase Kinase 3 beta; D006801:Humans; D007211:Indoles / Q000494:pharmacology; D008297:Male; D010091:Oximes / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D015854:Up-Regulation / Q000187:drug effects / Q000502:physiology; D051176:beta Catenin / Q000235:genetics / Q000502:physiology*
chemical_list: C483321:6-bromoindirubin-3'-oxime; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D007211:Indoles; D010091:Oximes; D051176:beta Catenin; D000071679:Glycogen Synthase Kinase 3 beta; D038362:Glycogen Synthase Kinase 3