title: Stabilizing effects of eicosapentaenoic acid on Kv1.5 channel protein expressed in mammalian cells.
abstract: We investigated the effects of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) on the stability of Kv1.5 channel protein. The expression and function of Kv1.5 (Kv1.5-FLAG) in transfected African green monkey kidney fibroblast cells as well as rat atrium were estimated by immunoblotting, immunoprecipitation, immunofluorescence and patch-clamp techniques. Both EPA and DHA immediately blocked Kv1.5 channel current in a dose-dependent manner, accompanied by reduction of their phosphorylation. Chronic treatment (for 12 h) with EPA at lower concentrations (0.3-10 muM) increased the level of Kv1.5-FLAG protein as well as Kv1.5 channel current without changes in its gating kinetics, prolonging its half-life; in contrast, both EPA and DHA at higher concentrations (30-100 muM) decreased the expression of Kv1.5-FLAG. EPA at the higher concentrations also decreased mRNA of Kv1.5 and synapse-associated protein 97 expression. EPA at the lower concentrations increased Kv1.5 expression in the endoplasmic reticulum, Golgi apparatus and cell membrane. EPA-induced increase of Kv1.5 channel expression and current was abolished by pretreatment with the protein transport inhibitor brefeldin A or colchicines, and by the Kv1.5 channel blocker 4-aminopyridine. Oral administration of EPA (30 mg/kg) increased the level of endogenous Kv1.5 in rat atria. These results indicate that chronic treatment with EPA at lower concentrations stabilizes Kv1.5 channel protein in the endoplasmic reticulum and Golgi apparatus thereby enhancing the Kv1.5 channel current on the cell membrane.
authors.affiliation: Division of Regenerative Medicine and Therapeutics, Department of Genetic Medicine and Regenerative Therapeutics, Institute of Regenerative Medicine and Biofunction, Tottori University Graduate School of Medical Science, Nishimachi 86, Yonago 683, Japan.
authors.forename: Shunya
authors.initials: S
authors.lastname: Koshida
authors.forename: Yasutaka
authors.initials: Y
authors.lastname: Kurata
authors.forename: Tomomi
authors.initials: T
authors.lastname: Notsu
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Hirota
authors.forename: Ting Y
authors.initials: TY
authors.lastname: Kuang
authors.forename: Peili
authors.initials: P
authors.lastname: Li
authors.forename: Udin
authors.initials: U
authors.lastname: Bahrudin
authors.forename: Shingo
authors.initials: S
authors.lastname: Harada
authors.forename: Junichiro
authors.initials: J
authors.lastname: Miake
authors.forename: Yasutaka
authors.initials: Y
authors.lastname: Yamamoto
authors.forename: Yoshiko
authors.initials: Y
authors.lastname: Hoshikawa
authors.forename: Osamu
authors.initials: O
authors.lastname: Igawa
authors.forename: Katsumi
authors.initials: K
authors.lastname: Higaki
authors.forename: Masaaki
authors.initials: M
authors.lastname: Soma
authors.forename: Akio
authors.initials: A
authors.lastname: Yoshida
authors.forename: Haruaki
authors.initials: H
authors.lastname: Ninomiya
authors.forename: Goshi
authors.initials: G
authors.lastname: Shiota
authors.forename: Yasuaki
authors.initials: Y
authors.lastname: Shirayoshi
authors.forename: Ichiro
authors.initials: I
authors.lastname: Hisatome
mesh_terms: D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D015153:Blotting, Western; D019556:COS Cells; D002522:Chlorocebus aethiops; D004281:Docosahexaenoic Acids / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D015118:Eicosapentaenoic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology; D005347:Fibroblasts / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D047468:Immunoprecipitation; D051666:Kv1.5 Potassium Channel / Q000096:biosynthesis*; D009842:Oligopeptides; D018408:Patch-Clamp Techniques; D010455:Peptides / Q000378:metabolism; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D055550:Protein Stability; D051381:Rats; D011921:Rats, Inbred WKY; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D008063:Thioctic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology; D014162:Transfection
chemical_list: D051666:Kv1.5 Potassium Channel; D009842:Oligopeptides; D010455:Peptides; D011993:Recombinant Fusion Proteins; C455277:eicosapentaenoate-lipoate; D004281:Docosahexaenoic Acids; D008063:Thioctic Acid; C085706:FLAG peptide; D015118:Eicosapentaenoic Acid; D046988:Proteasome Endopeptidase Complex