Normal function of HERG K+ channels expressed in HEK293 cells requires basal protein kinase B activity.
The potential role of protein kinase B (PKB), a serine/threonine protein kinase, in regulating HERG (human ether-a-go-go related gene) K(+) channel function was investigated. Wortmannin (a phosphoinositide 3-kinase (PI3K) inhibitor) caused approximately 30% reduction of HERG current (I(HERG)) stably expressed in HEK293 cells. Transient transfection with the constitutively active PI3K in HERG-expressing HEK293 cells slightly increased ( approximately 7%) I(HERG) while a dominant negative PI3K significantly reduced I(HERG) ( approximately 25%) relative to results in vehicle-transfected cells. I(HERG) was approximately 35% greater in cells transfected with the constitutively activated PKB (caPKB), whereas it was approximately 47% smaller in cells transfected with dominant negative PKB (dnPKB). Basal activation of PKB was detected by immunocytochemistry. PKB activity was significantly enhanced in caPKB-transfected cells and nearly abolished in dnPKB-transfected cells. We conclude that normal HERG function in HEK293 cells requires basal activity of PKB. Our data represent the first evidence that PKB phosphorylation regulates K(+) channels.
Zhang
Yiqiang
Y
Research Center, Montreal Heart Institute, Montreal, QC, Canada H1T 1C8.
Wang
Huizhen
H
Wang
Jingxiong
J
Han
Hong
H
Nattel
Stanley
S
Wang
Zhiguo
Z
D000730:Androstadienes / Q000494:pharmacology; D016827:CD8 Antigens / Q000378:metabolism; D027682:Cation Transport Proteins; D002460:Cell Line; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D004268:DNA-Binding Proteins; D000072237:ERG1 Potassium Channel; D004791:Enzyme Inhibitors / Q000494:pharmacology; D051638:Ether-A-Go-Go Potassium Channels; D005799:Genes, Dominant; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D007546:Isoquinolines / Q000494:pharmacology; D018408:Patch-Clamp Techniques; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation; D015221:Potassium Channels / Q000378:metabolism*; D024642:Potassium Channels, Voltage-Gated; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt; D013449:Sulfonamides; D015534:Trans-Activators; D000071230:Transcriptional Regulator ERG; D014162:Transfection; D000077191:Wortmannin
D000730:Androstadienes; D016827:CD8 Antigens; D027682:Cation Transport Proteins; D017868:Cyclic AMP-Dependent Protein Kinases; D004268:DNA-Binding Proteins; D000072237:ERG1 Potassium Channel; D004791:Enzyme Inhibitors; D051638:Ether-A-Go-Go Potassium Channels; D007546:Isoquinolines; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D015221:Potassium Channels; D024642:Potassium Channels, Voltage-Gated; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D013449:Sulfonamides; D015534:Trans-Activators; D000071230:Transcriptional Regulator ERG; D000077191:Wortmannin; C072312:ERG protein, human; C000606913:KCNH2 protein, human; C092509:KCNH6 protein, human; C063509:N-(2-(4-bromocinnamylamino)ethyl)-5-isoquinolinesulfonamide