title: Nedd4-2 modulates renal Na+-Cl- cotransporter via the aldosterone-SGK1-Nedd4-2 pathway.
abstract: Regulation of renal Na(+) transport is essential for controlling blood pressure, as well as Na(+) and K(+) homeostasis. Aldosterone stimulates Na(+) reabsorption by the Na(+)-Cl(-) cotransporter (NCC) in the distal convoluted tubule (DCT) and by the epithelial Na(+) channel (ENaC) in the late DCT, connecting tubule, and collecting duct. Aldosterone increases ENaC expression by inhibiting the channel's ubiquitylation and degradation; aldosterone promotes serum-glucocorticoid-regulated kinase SGK1-mediated phosphorylation of the ubiquitin-protein ligase Nedd4-2 on serine 328, which prevents the Nedd4-2/ENaC interaction. It is important to note that aldosterone increases NCC protein expression by an unknown post-translational mechanism. Here, we present evidence that Nedd4-2 coimmunoprecipitated with NCC and stimulated NCC ubiquitylation at the surface of transfected HEK293 cells. In Xenopus laevis oocytes, coexpression of NCC with wild-type Nedd4-2, but not its catalytically inactive mutant, strongly decreased NCC activity and surface expression. SGK1 prevented this inhibition in a kinase-dependent manner. Furthermore, deficiency of Nedd4-2 in the renal tubules of mice and in cultured mDCT(15) cells upregulated NCC. In contrast to ENaC, Nedd4-2-mediated inhibition of NCC did not require the PY-like motif of NCC. Moreover, the mutation of Nedd4-2 at either serine 328 or 222 did not affect SGK1 action, and mutation at both sites enhanced Nedd4-2 activity and abolished SGK1-dependent inhibition. Taken together, these results suggest that aldosterone modulates NCC protein expression via a pathway involving SGK1 and Nedd4-2 and provides an explanation for the well-known aldosterone-induced increase in NCC protein expression.
authors.affiliation: Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Instituto Mexico City, Mexico.
authors.forename: Juan Pablo
authors.initials: JP
authors.lastname: Arroyo
authors.forename: Dagmara
authors.initials: D
authors.lastname: Lagnaz
authors.forename: Caroline
authors.initials: C
authors.lastname: Ronzaud
authors.forename: Norma
authors.initials: N
authors.lastname: Vázquez
authors.forename: Benjamin S
authors.initials: BS
authors.lastname: Ko
authors.forename: Lauren
authors.initials: L
authors.lastname: Moddes
authors.forename: Dorothée
authors.initials: D
authors.lastname: Ruffieux-Daidié
authors.forename: Pierrette
authors.initials: P
authors.lastname: Hausel
authors.forename: Robert
authors.initials: R
authors.lastname: Koesters
authors.forename: Baoli
authors.initials: B
authors.lastname: Yang
authors.forename: John B
authors.initials: JB
authors.lastname: Stokes
authors.forename: Robert S
authors.initials: RS
authors.lastname: Hoover
authors.forename: Gerardo
authors.initials: G
authors.lastname: Gamba
authors.forename: Olivier
authors.initials: O
authors.lastname: Staub
mesh_terms: D043209:11-beta-Hydroxysteroid Dehydrogenase Type 2 / Q000378:metabolism; D000450:Aldosterone / Q000378:metabolism*; D000818:Animals; D015536:Down-Regulation; D056827:Endosomal Sorting Complexes Required for Transport / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D017874:Immediate-Early Proteins / Q000378:metabolism*; D007686:Kidney Tubules, Distal / Q000201:enzymology*; D051379:Mice; D018345:Mice, Knockout; D000075702:Nedd4 Ubiquitin Protein Ligases; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D015398:Signal Transduction; D049992:Sodium Chloride Symporters / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism*; D054875:Ubiquitination; D029867:Xenopus Proteins; D014982:Xenopus laevis; D000099184:Serum-Glucocorticoid Regulated Kinases
chemical_list: D043209:11-beta-Hydroxysteroid Dehydrogenase Type 2; D000450:Aldosterone; D056827:Endosomal Sorting Complexes Required for Transport; D017874:Immediate-Early Proteins; D000075702:Nedd4 Ubiquitin Protein Ligases; D017346:Protein Serine-Threonine Kinases; D049992:Sodium Chloride Symporters; D044767:Ubiquitin-Protein Ligases; D029867:Xenopus Proteins; D000099184:Serum-Glucocorticoid Regulated Kinases; C000618482:Nedd4 protein, Xenopus; C000618483:Nedd4 protein, human; C000618485:Nedd4L protein, human; C000618461:Nedd4l protein, mouse; C000618460:nedd4l protein, Xenopus