Stabilizing effects of eicosapentaenoic acid on Kv1.5 channel protein expressed in mammalian cells.
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.
Koshida
Shunya
S
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.
Kurata
Yasutaka
Y
Notsu
Tomomi
T
Hirota
Yutaka
Y
Kuang
Ting Y
TY
Li
Peili
P
Bahrudin
Udin
U
Harada
Shingo
S
Miake
Junichiro
J
Yamamoto
Yasutaka
Y
Hoshikawa
Yoshiko
Y
Igawa
Osamu
O
Higaki
Katsumi
K
Soma
Masaaki
M
Yoshida
Akio
A
Ninomiya
Haruaki
H
Shiota
Goshi
G
Shirayoshi
Yasuaki
Y
Hisatome
Ichiro
I
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
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