High impact information on Nedd4l

• The kinase Grk2 regulates Nedd4/Nedd4-2-dependent control of epithelial Na+ channels [1].
• Participation of the ubiquitin-conjugating enzyme UBE2E3 in Nedd4-2-dependent regulation of the epithelial Na+ channel [2].
• In Xenopus laevis oocytes, UBE2E3 reduces ENaC activity marginally, consistent with Nedd4-2 being the rate-limiting factor in this process, whereas a catalytically inactive mutant of UBE2E3 (UBE2E3-CS) causes elevated ENaC activity by increasing cell surface expression [2].
• Previously we showed that these PY motifs serve as binding sites for the E3 enzyme Nedd4-2, implying ubiquitination as a regulatory mechanism of ENaC [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 [3].

Biological context of Nedd4l

• Incubation of cell extracts with a selective phospho-Nedd4-2 antibody blocked the aldosterone-induced association of 14-3-3beta with Nedd4-2, implicating SGK1 phosphorylation at Ser-328 as the primary site of 14-3-3beta binding [4].
• These findings indicate that AMPK-dependent ENaC inhibition is mediated through a decrease in the number of active channels at the plasma membrane (N), presumably through enhanced Nedd4-2-dependent ENaC endocytosis [5].
• Because there are four WW domains in Nedd4-2, we analyzed binding kinetics and affinity between individual WW domains and ENaC subunits [6].

Anatomical context of Nedd4l

• 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 [3].
• Here it is shown, with the use of an anti-phospho-Ser328-mNedd4-2 antibody, that 2 to 6 h of aldosterone treatment induces an increase in Nedd4-2 phosphorylation, both in a mouse cortical collecting duct cell line (mpkCCDcl4) and in kidneys of adrenalectomized rats [7].

Associations of Nedd4l with chemical compounds

• We evaluated the hypothesis that 14-3-3 proteins participate in the aldosterone-mediated regulation of ENaC by associating with phosphorylated Nedd4-2 [4].

Physical interactions of Nedd4l

• We were also unable to confirm that Sgk directly interacts with Nedd4-2 in vitro [8].

Other interactions of Nedd4l

• Channels containing the T635(D/E) substitution in gamma-mENaC did not have increased basal activity and responded to Nedd4-2 but not K44A [9].
• Hence, these data provide evidence in cortical collecting duct cells in vitro and in vivo that Sgk1-dependent phosphorylation of Nedd4-2 is part of the aldosterone response [7].
• Our studies show that aldosterone increases the expression of 14-3-3beta, which interacts with phospho-Nedd4-2 to block its interaction with ENaC, thus enhancing sodium absorption by increasing apical membrane ENaC density [4].
• Aldosterone-induced serum and glucocorticoid-induced kinase 1 expression is accompanied by Nedd4-2 phosphorylation and increased Na+ transport in cortical collecting duct cells [7].

References