Interaction of serum- and glucocorticoid regulated kinase 1 (SGK1) with the WW-domains of Nedd4-2 is required for epithelial sodium channel regulation.

The epithelial sodium channel (ENaC) is an integral component of the pathway for Na(+) absorption in epithelial cells. The ubiquitin ligases Nedd4 and Nedd4-2 bind to ENaC and decrease its activity. Conversely, Serum- and Glucocorticoid regulated Kinase-1 (SGK1), a downstream mediator of aldosterone, increases ENaC activity. This effect is at ...
least partly mediated by direct interaction between SGK and Nedd4-2. SGK binds both Nedd4 and Nedd4-2, but it is only able to phosphorylate Nedd4-2. Phosphorylation of Nedd4-2 reduces its ability to bind to ENaC, due to the interaction of phosphorylated Nedd4-2 with 14-3-3 proteins, and hence increases ENaC activity. WW-domains in Nedd4-like proteins bind PY-motifs (PPXY) present in ENaC subunits, and SGK also has a PY-motif.Here we show that single or tandem WW-domains of Nedd4 and Nedd4-2 mediate binding to SGK and that different WW-domains of Nedd4 and Nedd4-2 are involved. Our data also show that WW-domains 2 and 3 of Nedd4-2 mediate the interaction with SGK in a cooperative manner, that activated SGK has increased affinity for the WW-domains of Nedd4-2 in vitro, and a greater stimulatory effect on ENaC Na(+) transport compared to wildtype SGK. Further, SGK lacking a PY motif failed to stimulate ENaC activity in the presence of Nedd4-2.Binding of Nedd4-2 WW-domains to SGK is necessary for SGK-induced ENaC activity.
Mesh Terms:
Amino Acid Motifs, Animals, COS Cells, Cercopithecus aethiops, Dose-Response Relationship, Drug, Endosomal Sorting Complexes Required for Transport, Enzyme Activation, Epithelial Sodium Channel, Immediate-Early Proteins, Models, Molecular, Peptide Fragments, Protein Binding, Protein Structure, Tertiary, Protein-Serine-Threonine Kinases, Tryptophan, Ubiquitin-Protein Ligases
PLoS ONE
Date: Aug. 24, 2010
Download Curated Data For This Publication
139504
Switch View:
  • Interactions 2