title: Induction of aquaporin 1 by dexamethasone in lipid rafts in immortalized brain microvascular endothelial cells.
abstract: Water homeostasis in the brain is essential for brain function. We have studied how aquaporin (AQP) 1 expression in GP8 immortalized rat brain microvascular endothelial cells is regulated by glucocorticoid. AQP1 protein level was raised by dexamethasone treatment in a time- and concentration-dependent manner. The up-regulation of AQP1 protein by dexamethasone was associated with an increase of AQP1 mRNA level, with no change in the degradation rate of AQP1 mRNA. AQP1 was concentrated in detergent-insoluble fractions in the cells treated with or without dexamethasone, suggesting that function/trafficking of AQP1 may be regulated via the interaction with lipid rafts. Since glucocorticoid therapy has well known beneficial effects in the treatment of brain edema, the induction of AQP1 by dexamethasone raises a possibility that AQP1 plays a role in ameliorating brain edema.
authors.affiliation: Department of Pharmacology, Miyazaki Medical College, University of Miyazaki, 5200 Kihara, Kiyotake, Miyazaki 889-1692, Japan. hkobayas@med.miyazaki-u.ac.jp
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Kobayashi
authors.forename: Hiroki
authors.initials: H
authors.lastname: Yokoo
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Yanagita
authors.forename: Shinya
authors.initials: S
authors.lastname: Satoh
authors.forename: Bela
authors.initials: B
authors.lastname: Kis
authors.forename: Maria
authors.initials: M
authors.lastname: Deli
authors.forename: Masami
authors.initials: M
authors.lastname: Niwa
authors.forename: Akihiko
authors.initials: A
authors.lastname: Wada
mesh_terms: D000818:Animals; D051398:Aquaporin 1 / Q000235:genetics / Q000378:metabolism*; D001921:Brain / Q000098:blood supply / Q000166:cytology; D002196:Capillaries / Q000166:cytology / Q000378:metabolism; D002460:Cell Line; D003907:Dexamethasone / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D042783:Endothelial Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D005938:Glucocorticoids / Q000494:pharmacology*; D008297:Male; D021962:Membrane Microdomains / Q000187:drug effects / Q000378:metabolism*; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors; D015854:Up-Regulation
chemical_list: D005938:Glucocorticoids; D012333:RNA, Messenger; D051398:Aquaporin 1; D003907:Dexamethasone