title: Nedd4-2-dependent ubiquitylation and regulation of the cardiac potassium channel hERG1.
abstract: The voltage-gated cardiac potassium channel hERG1 (human ether-à-gogo-related gene 1) plays a key role in the repolarization phase of the cardiac action potential (AP). Mutations in its gene, KCNH2, can lead to defects in the biosynthesis and maturation of the channel, resulting in congenital long QT syndrome (LQTS). To identify the molecular mechanisms regulating the density of hERG1 channels at the plasma membrane, we investigated channel ubiquitylation by ubiquitin ligase Nedd4-2, a post-translational regulatory mechanism previously linked to other ion channels. We found that whole-cell hERG1 currents recorded in HEK293 cells were decreased upon neural precursor cell expressed developmentally down-regulated 4-2 (Nedd4-2) co-expression. The amount of hERG1 channels in total HEK293 lysates and at the cell surface, as assessed by Western blot and biotinylation assays, respectively, were concomitantly decreased. Nedd4-2 and hERG1 interact via a PY motif located in the C-terminus of hERG1. Finally, we determined that Nedd4-2 mediates ubiquitylation of hERG1 and that deletion of this motif affects Nedd4-2-dependent regulation. These results suggest that ubiquitylation of the hERG1 protein by Nedd4-2, and its subsequent down-regulation, could represent an important mechanism for modulation of the duration of the human cardiac action potential.
authors.affiliation: Department of Clinical Research, University of Bern, Switzerland.
authors.forename: Maxime
authors.initials: M
authors.lastname: Albesa
authors.forename: Liliana Sintra
authors.initials: LS
authors.lastname: Grilo
authors.forename: Bruno
authors.initials: B
authors.lastname: Gavillet
authors.forename: Hugues
authors.initials: H
authors.lastname: Abriel
mesh_terms: D000200:Action Potentials; D000818:Animals; D019921:Biotinylation; D015153:Blotting, Western; D056827:Endosomal Sorting Complexes Required for Transport / Q000235:genetics / Q000378:metabolism*; D051638:Ether-A-Go-Go Potassium Channels / Q000235:genetics* / Q000378:metabolism*; D006168:Guinea Pigs; D057809:HEK293 Cells; D006801:Humans; D047468:Immunoprecipitation; D015640:Ion Channel Gating / Q000235:genetics; D008133:Long QT Syndrome / Q000235:genetics; D009154:Mutation; D009206:Myocardium / Q000378:metabolism; D000075702:Nedd4 Ubiquitin Protein Ligases; D018408:Patch-Clamp Techniques; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism*; D054875:Ubiquitination
chemical_list: D056827:Endosomal Sorting Complexes Required for Transport; D051638:Ether-A-Go-Go Potassium Channels; C496884:KCNH1 protein, human; D000075702:Nedd4 Ubiquitin Protein Ligases; C000618483:Nedd4 protein, human; C000618485:Nedd4L protein, human; D044767:Ubiquitin-Protein Ligases