Pharmacological rescue of trafficking defective HERG channels formed by coassembly of wild-type and long QT mutant N470D subunits.
Mutations in the human ether-a-go-go-related gene (HERG) cause long QT syndrome. We previously showed that the HERG N470D mutation expressed as homotetrameric channels causes a protein trafficking defect, and this can be corrected by the HERG channel blocking drug E-4031. The N470D mutant also has been reported to cause dominant negative suppression of HERG current when coexpressed with wild-type channel subunits. The aims of this study were 1). to investigate the molecular mechanism responsible for the dominant negative effect of the N470D mutant coexpressed with wild-type subunits and 2). to test whether the trafficking defective heteromeric channels could be pharmacologically rescued by E-4031. Using a combination of immunoprecipitation and Western blot methods, we showed that N470D mutant and wild-type HERG subunits were physically associated in the endoplasmic reticulum as heteromeric channels. The coassembly resulted in the retention of both wild-type and N470D subunits in the endoplasmic reticulum. Culturing cells in E-4031 increased the cell surface expression of these channels, although with an altered electrophysiological phenotype. These results suggest that the dominant negative effect of the N470D wild-type coassembled channels is caused by retention of heteromeric channels in the endoplasmic reticulum and that the trafficking defect of these channels can be corrected by specific pharmacological strategies.
Gong
Qiuming
Q
Deparrtment of Medicine, Oregon Health and Science University, Portland, OR 97239, USA.
Anderson
Corey L
CL
January
Craig T
CT
Zhou
Zhengfeng
Z
D027682:Cation Transport Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism; D051638:Ether-A-Go-Go Potassium Channels; D005799:Genes, Dominant; D006801:Humans; D008133:Long QT Syndrome / Q000235:genetics*; D009154:Mutation; D018408:Patch-Clamp Techniques; D010641:Phenotype; D010880:Piperidines / Q000494:pharmacology; D015221:Potassium Channels / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D024642:Potassium Channels, Voltage-Gated; D011725:Pyridines / Q000494:pharmacology
D027682:Cation Transport Proteins; D051638:Ether-A-Go-Go Potassium Channels; C092509:KCNH6 protein, human; D010880:Piperidines; D015221:Potassium Channels; D024642:Potassium Channels, Voltage-Gated; D011725:Pyridines; C063968:E 4031