A novel mouse Nedd4 protein suppresses the activity of the epithelial Na+ channel.
Liddle's syndrome is a form of inherited hypertension linked to mutations in the genes encoding the epithelial Na+ channel (ENaC). These mutations alter or delete PY motifs involved in protein-protein interactions with a ubiquitin-protein ligase, Nedd4. Here we show that Na+ transporting cells, derived from mouse cortical collecting duct, express two Nedd4 proteins with different structural organization and characteristics of ENaC regulation: 1) the classical Nedd4 (herein referred to as Nedd4-1) containing one amino-terminal C2, three WW, and one HECT-ubiquitin protein ligase domain and 2) a novel Nedd4 protein (Nedd4-2), homologous to Xenopus Nedd4 and comprising four WW, one HECT, yet lacking a C2 domain. Nedd4-2, but not Nedd4-1, inhibits ENaC activity when coexpressed in Xenopus oocytes and this property correlates with the ability to bind to ENaC, as only Nedd4-2 coimmunoprecipitates with ENaC. Furthermore, this interaction depends on the presence of at least one PY motif in the ENaC complex and on WW domains 3 and 4 in Nedd4-2. Thus, these results suggest that the novel suppressor protein Nedd4-2 is the regulator of ENaC and hence a potential susceptibility gene for arterial hypertension.
Kamynina
E
E
Institute of Pharmacology and Toxicology, University of Lausanne, 1005 Lausanne, Switzerland.
Debonneville
C
C
Bens
M
M
Vandewalle
A
A
Staub
O
O
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002135:Calcium-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D003001:Cloning, Molecular; D056827:Endosomal Sorting Complexes Required for Transport; D008025:Ligases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D009154:Mutation; D000075702:Nedd4 Ubiquitin Protein Ligases; D009865:Oocytes / Q000187:drug effects / Q000378:metabolism; D011485:Protein Binding; D020033:Protein Isoforms / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary; D012333:RNA, Messenger / Q000032:analysis / Q000235:genetics; D051381:Rats; D016415:Sequence Alignment; D026941:Sodium Channel Blockers; D015222:Sodium Channels / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases; D029867:Xenopus Proteins; D014982:Xenopus laevis
D002135:Calcium-Binding Proteins; D056827:Endosomal Sorting Complexes Required for Transport; D020033:Protein Isoforms; D012333:RNA, Messenger; D026941:Sodium Channel Blockers; D015222:Sodium Channels; D029867:Xenopus Proteins; C000618479:NEDD4L protein, rat; D000075702:Nedd4 Ubiquitin Protein Ligases; C000618482:Nedd4 protein, Xenopus; C000618484:Nedd4 protein, rat; C000618461:Nedd4l protein, mouse; C000618460:nedd4l protein, Xenopus; D044767:Ubiquitin-Protein Ligases; D008025:Ligases