title: Methyl-beta-cyclodextrin reversibly alters the gating of lipid rafts-associated Kv1.3 channels in Jurkat T lymphocytes.
abstract: The voltage-dependent Kv1.3 potassium channels mediate a variety of physiological functions in human T lymphocytes. These channels, along with their multiple regulatory components, are localized in cholesterol-enriched microdomains of plasma membrane (lipid rafts). In this study, patch-clamp technique was applied to explore the impact of the lipid-raft integrity on the Kv1.3 channel functional characteristics. T lymphoma Jurkat cells were treated for 1 h with cholesterol-binding oligosaccharide methyl-beta-cyclodextrin (MbetaCD) in 1 or 2 mM concentration, resulting in depletion of cholesterol by 63 +/- 5 or 75 +/- 4%, respectively. Treatment with 2 mM MbetaCD did not affect the cells viability but retarded the cell proliferation. The latter treatment caused a depolarizing shift of the Kv1.3 channel activation and inactivation by 11 and 6 mV, respectively, and more than twofold decrease in the steady-state activity at depolarizing potentials. Altogether, these changes underlie the depolarization of membrane potential, recorded in a current-clamp mode. The effects of MbetaCD were concentration- and time-dependent and reversible. Both development and recovery of the MbetaCD effects were completed within 1-2 h. Therefore, cholesterol depletion causes significant alterations in the Kv1.3 channel function, whereas T cells possess a potential to reverse these changes.
authors.affiliation: Centro Universitario de Investigaciones Biomédicas (CUIB), Universidad de Colima, Av. 25 de Julio 965, Villa San Sebastian, 28045 Colima, Colima, Mexico.
authors.forename: Igor I
authors.initials: II
authors.lastname: Pottosin
authors.forename: Georgina
authors.initials: G
authors.lastname: Valencia-Cruz
authors.forename: Edgar
authors.initials: E
authors.lastname: Bonales-Alatorre
authors.forename: Sergey N
authors.initials: SN
authors.lastname: Shabala
authors.forename: Oxana R
authors.initials: OR
authors.lastname: Dobrovinskaya
mesh_terms: D002462:Cell Membrane / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D002784:Cholesterol / Q000378:metabolism; D004558:Electric Stimulation; D004594:Electrophysiology; D006801:Humans; D015640:Ion Channel Gating / Q000187:drug effects*; D019169:Jurkat Cells; D007700:Kinetics; D051664:Kv1.3 Potassium Channel / Q000378:metabolism / Q000502:physiology*; D021962:Membrane Microdomains / Q000378:metabolism*; D013601:T-Lymphocytes / Q000187:drug effects / Q000378:metabolism; D047392:beta-Cyclodextrins / Q000494:pharmacology*
chemical_list: D051664:Kv1.3 Potassium Channel; D047392:beta-Cyclodextrins; C108732:methyl-beta-cyclodextrin; D002784:Cholesterol