Regulation of neuronal voltage-gated sodium channels by the ubiquitin-protein ligases Nedd4 and Nedd4-2.
Nedd4 and Nedd4-2 are ubiquitin-protein ligases known to regulate a number of membrane proteins including receptors and ion transporters. Regulation of the epithelial Na(+) channel by Nedd4 and Nedd4-2 is mediated via interactions between the PY motifs of the epithelial sodium channel subunits and the Nedd4/Nedd4-2 WW domains. This example serves as a model for the regulation of other PY motif-containing ion channels by Nedd4 and Nedd4-2. We found that the carboxyl termini of the six voltage-gated Na(+) (Na(v)) channels contain typical PY motifs (PPXY), and a further Na(v) contains a PY motif variant (LPXY). Not only did we demonstrate by Far-Western analysis that Nedd4 and Nedd4-2 interact with the PY motif-containing Na(v) channels, but we also showed that these channels have conserved WW domain binding specificity. We further showed that the carboxyl termini fusion proteins of one central nervous system and one peripheral nervous system-derived Na(+) channel (Na(v)1.2 and Na(v)1.7, respectively) are readily ubiquitinated by Nedd4-2. In Xenopus oocytes, Nedd4-2 strongly inhibited the activities of all three Na(v)s (Na(v)1.2, Na(v)1.7, and Na(v)1.8) tested. Interestingly, Nedd4 suppressed the activity of Na(v)1.2 and Na(v)1.7 but was a poor inhibitor of Na(v)1.8. Our results provide evidence that Nedd4 and Nedd4-2 are likely to be key regulators of specific neuronal Na(v) channels in vivo.
Fotia
Andrew B
AB
Hanson Institute, Institute of Medical and Veterinary Science, Frome Road, Adelaide, South Australia 5000, Australia.
Ekberg
Jenny
J
Adams
David J
DJ
Cook
David I
DI
Poronnik
Philip
P
Kumar
Sharad
S
D000595:Amino Acid Sequence; D000818:Animals; D056827:Endosomal Sorting Complexes Required for Transport; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D000075702:Nedd4 Ubiquitin Protein Ligases; D009474:Neurons / Q000378:metabolism*; D009865:Oocytes / Q000502:physiology; D018408:Patch-Clamp Techniques; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D015222:Sodium Channels / Q000235:genetics / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism*; D014981:Xenopus; D029867:Xenopus Proteins
D056827:Endosomal Sorting Complexes Required for Transport; D011993:Recombinant Fusion Proteins; D015222:Sodium Channels; D029867:Xenopus Proteins; D000075702:Nedd4 Ubiquitin Protein Ligases; C000618482:Nedd4 protein, Xenopus; C000618483:Nedd4 protein, human; C000618485:Nedd4L protein, human; C000618461:Nedd4l protein, mouse; C000618460:nedd4l protein, Xenopus; D044767:Ubiquitin-Protein Ligases