title: L539 fs/47, a truncated mutation of human ether-a-go-go-related gene (hERG), decreases hERG ion channel currents in HEK 293 cells.
abstract: Mutations in the human ether-a-go-go-related gene (hERG) are responsible for congenital Type 2 long QT syndrome (LQT2). Previously, we reported a truncated mutation of hERG in a Chinese family with LQT2, namely L539 fs/47, which is composed of a 19 bp deletion mutation and an A1692G polymorphism. This mutation was found to cause an LQT2 phenotype. The aim of the present study was to investigate the functional role of L539 fs/47 at the cellular level and its potential contribution to the loss of function of hERG channels. The function of the truncated mutation L539 fs/47 was evaluated by constructing a mutated plasmid, transfection of the mutated cDNA into HEK 293 cells and subsequent patch-clamp, western blotting and immunostaining experiments. Homologous expression of L539 fs/47 in HEK 293 cells produced a non-functional protein that was detected in cell membranes. When L539 fs/47 was expressed simultaneously with wild-type hERG, it suppressed wild-type hERG currents in a dose-dependent manner and changed the gating properties of the channel. Although L539 fs/47 hERG proteins were detected on plasma membranes, they failed to generate hERG currents. In general, L539 fs/47 dose-dependently decreases hERG ion channel currents and suppresses the function of wild-type channels function. This may explain, in part, the clinical manifestations of LQT2 in the family with this mutation.
authors.affiliation: Department of Cardiovascular Medicine, MOE, Ion Channel Disease Laboratory, MOE Key Laboratory of Environment and Genes Related to Diseases, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi, China.
authors.forename: Aifeng
authors.initials: A
authors.lastname: Zhang
authors.forename: Chaofeng
authors.initials: C
authors.lastname: Sun
authors.forename: Li
authors.initials: L
authors.lastname: Zhang
authors.forename: Ying
authors.initials: Y
authors.lastname: Lv
authors.forename: Xiaolin
authors.initials: X
authors.lastname: Xue
authors.forename: Guoliang
authors.initials: G
authors.lastname: Li
authors.forename: Changcong
authors.initials: C
authors.lastname: Cui
authors.forename: Gan-Xin
authors.initials: GX
authors.lastname: Yan
mesh_terms: D001483:Base Sequence; D002460:Cell Line; D002462:Cell Membrane / Q000235:genetics / Q000378:metabolism; D000072237:ERG1 Potassium Channel; D051638:Ether-A-Go-Go Potassium Channels / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D005260:Female; D057809:HEK293 Cells; D006801:Humans; D008133:Long QT Syndrome / Q000235:genetics / Q000378:metabolism; D008297:Male; D008564:Membrane Potentials / Q000235:genetics; D009154:Mutation; D010375:Pedigree; D010641:Phenotype; D014162:Transfection
chemical_list: D000072237:ERG1 Potassium Channel; D051638:Ether-A-Go-Go Potassium Channels; C000606913:KCNH2 protein, human