title: Rab11-dependent Recycling of the Human Ether-a-go-go-related Gene (hERG) Channel.
abstract: The human ether-a-go-go-related gene (hERG) encodes the pore-forming subunit of the rapidly activating delayed rectifier potassium channel (IKr). A reduction in the hERG current causes long QT syndrome, which predisposes affected individuals to ventricular arrhythmias and sudden death. We reported previously that hERG channels in the plasma membrane undergo vigorous internalization under low K(+) conditions. In the present study, we addressed whether hERG internalization occurs under normal K(+) conditions and whether/how internalized channels are recycled back to the plasma membrane. Using patch clamp, Western blot, and confocal imaging analyses, we demonstrated that internalized hERG channels can effectively recycle back to the plasma membrane. Low K(+)-enhanced hERG internalization is accompanied by an increased rate of hERG recovery in the plasma membrane upon reculture following proteinase K-mediated clearance of cell-surface proteins. The increased recovery rate is not due to enhanced protein synthesis, as hERG mRNA expression was not altered by low K(+) exposure, and the increased recovery was observed in the presence of the protein biosynthesis inhibitor cycloheximide. GTPase Rab11, but not Rab4, is involved in the recycling of hERG channels. Interfering with Rab11 function not only delayed hERG recovery in cells after exposure to low K(+) medium but also decreased hERG expression and function in cells under normal culture conditions. We concluded that the recycling pathway plays an important role in the homeostasis of plasma membrane-bound hERG channels.
authors.affiliation: Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario K7L 3N6, Canada.
authors.forename: Jeffery
authors.initials: J
authors.lastname: Chen
authors.affiliation: Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario K7L 3N6, Canada.
authors.forename: Jun
authors.initials: J
authors.lastname: Guo
authors.affiliation: Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario K7L 3N6, Canada.
authors.forename: Tonghua
authors.initials: T
authors.lastname: Yang
authors.affiliation: Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario K7L 3N6, Canada.
authors.forename: Wentao
authors.initials: W
authors.lastname: Li
authors.affiliation: Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario K7L 3N6, Canada.
authors.forename: Shawn M
authors.initials: SM
authors.lastname: Lamothe
authors.affiliation: Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario K7L 3N6, Canada.
authors.forename: Yudi
authors.initials: Y
authors.lastname: Kang
authors.affiliation: Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario K7L 3N6, Canada.
authors.forename: John A
authors.initials: JA
authors.lastname: Szendrey
authors.affiliation: Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario K7L 3N6, Canada. Electronic address: shetuan.zhang@queensu.ca.
authors.forename: Shetuan
authors.initials: S
authors.lastname: Zhang
mesh_terms: D000595:Amino Acid Sequence; D002462:Cell Membrane / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*; D003513:Cycloheximide / Q000494:pharmacology; D000072237:ERG1 Potassium Channel; D019286:Endopeptidase K / Q000737:chemistry; D051638:Ether-A-Go-Go Potassium Channels / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression; D057809:HEK293 Cells; D006801:Humans; D017136:Ion Transport; D008969:Molecular Sequence Data; D018408:Patch-Clamp Techniques; D011188:Potassium / Q000378:metabolism*; D021381:Protein Transport; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism*; D020691:rab GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D020695:rab4 GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D000099193:rab11 GTP-Binding Proteins
chemical_list: D003513:Cycloheximide; D000072237:ERG1 Potassium Channel; D019286:Endopeptidase K; D051638:Ether-A-Go-Go Potassium Channels; D011188:Potassium; D012333:RNA, Messenger; D020691:rab GTP-Binding Proteins; D020695:rab4 GTP-Binding Proteins; D000099193:rab11 GTP-Binding Proteins; C000606913:KCNH2 protein, human
keywords: cell-surface protein; electrophysiology; hERG; patch clamp; potassium channel; trafficking