title: Cell surface expression of human ether-a-go-go-related gene (hERG) channels is regulated by caveolin-3 protein via the ubiquitin ligase Nedd4-2.
abstract: The human ether-a-go-go-related gene (hERG) encodes the rapidly activating delayed rectifier potassium channel (I(Kr)) which plays an important role in cardiac repolarization. A reduction or increase in hERG current can cause long or short QT syndrome, respectively, leading to fatal cardiac arrhythmias. The channel density in the plasma membrane is a key determinant of the whole cell current amplitude. To gain insight into the molecular mechanisms for the regulation of hERG density at the plasma membrane, we used whole cell voltage clamp, Western blotting, and immunocytochemical methods to investigate the effects of an integral membrane protein, caveolin-3 (Cav3) on hERG expression levels. Our data demonstrate that Cav3, hERG, and ubiquitin-ligase Nedd4-2 interact with each other and form a complex. Expression of Cav3 thus enhances the hERG-Nedd4-2 interaction, leading to an increased ubiquitination and degradation of mature, plasma-membrane localized hERG channels. Disrupting Nedd4-2 interaction with hERG by mutations eliminates the effects of Cav3 on hERG channels. Knockdown of endogenous Cav3 or Nedd4-2 in cultured neonatal rat ventricular myocytes using siRNA led to an increase in native I(Kr). Our data demonstrate that hERG expression in the plasma membrane is regulated by Cav3 via Nedd4-2. These findings extend our understanding of the regulation of hERG channels and cardiac electrophysiology.
authors.affiliation: Department of Biomedical and Molecular Sciences, Queen’s University, Kingston, Ontario, Canada.
authors.forename: Jun
authors.initials: J
authors.lastname: Guo
authors.forename: Tingzhong
authors.initials: T
authors.lastname: Wang
authors.forename: Xian
authors.initials: X
authors.lastname: Li
authors.forename: Heidi
authors.initials: H
authors.lastname: Shallow
authors.forename: Tonghua
authors.initials: T
authors.lastname: Yang
authors.forename: Wentao
authors.initials: W
authors.lastname: Li
authors.forename: Jianmin
authors.initials: J
authors.lastname: Xu
authors.forename: Michael D
authors.initials: MD
authors.lastname: Fridman
authors.forename: Xiaolong
authors.initials: X
authors.lastname: Yang
authors.forename: Shetuan
authors.initials: S
authors.lastname: Zhang
mesh_terms: D000818:Animals; D051244:Caveolin 3 / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D056827:Endosomal Sorting Complexes Required for Transport / Q000378:metabolism*; D051638:Ether-A-Go-Go Potassium Channels / Q000378:metabolism*; D005260:Female; D005786:Gene Expression Regulation; D057809:HEK293 Cells; D006352:Heart Ventricles / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D008297:Male; D032342:Muscle Cells / Q000166:cytology; D000075702:Nedd4 Ubiquitin Protein Ligases; D018408:Patch-Clamp Techniques; D017354:Point Mutation; D034741:RNA, Small Interfering / Q000378:metabolism; D051381:Rats; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism*
chemical_list: C417736:CAV3 protein, human; D051244:Caveolin 3; D056827:Endosomal Sorting Complexes Required for Transport; D051638:Ether-A-Go-Go Potassium Channels; C092509:KCNH6 protein, human; C109500:Kcnh6 protein, rat; D034741:RNA, Small Interfering; C000618479:NEDD4L protein, rat; D000075702:Nedd4 Ubiquitin Protein Ligases; C000618483:Nedd4 protein, human; C000618484:Nedd4 protein, rat; C000618485:Nedd4L protein, human; D044767:Ubiquitin-Protein Ligases