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XB-ART-43736
J Am Soc Nephrol 2011 Sep 01;229:1707-19. doi: 10.1681/ASN.2011020132.
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Nedd4-2 modulates renal Na+-Cl- cotransporter via the aldosterone-SGK1-Nedd4-2 pathway.

Arroyo JP , Lagnaz D , Ronzaud C , Vázquez N , Ko BS , Moddes L , Ruffieux-Daidié D , Hausel P , Koesters R , Yang B , Stokes JB , Hoover RS , Gamba G , Staub O .


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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.

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Species referenced: Xenopus laevis
Genes referenced: dct nedd4 nedd4l sgk1 slc12a3

References [+] :
Abdallah, Loop diuretic infusion increases thiazide-sensitive Na(+)/Cl(-)-cotransporter abundance: role of aldosterone. 2001, Pubmed