Article: article from journal or magazin.
Salt-sensitive hypertension and cardiac hypertrophy in mice deficient in the ubiquitin ligase Nedd4-2.
American Journal of Physiology. Renal physiology
Nedd4-2 has been proposed to play a critical role in regulating epithelial Na+ channel (ENaC) activity. Biochemical and overexpression experiments suggest that Nedd4-2 binds to the PY motifs of ENaC subunits via its WW domains, ubiquitinates them, and decreases their expression on the apical membrane. Phosphorylation of Nedd4-2 (for example by Sgk1) may regulate its binding to ENaC, and thus ENaC ubiquitination. These results suggest that the interaction between Nedd4-2 and ENaC may play a crucial role in Na+ homeostasis and blood pressure (BP) regulation. To test these predictions in vivo, we generated Nedd4-2 null mice. The knockout mice had higher BP on a normal diet and a further increase in BP when on a high-salt diet. The hypertension was probably mediated by ENaC overactivity because 1) Nedd4-2 null mice had higher expression levels of all three ENaC subunits in kidney, but not of other Na+ transporters; 2) the downregulation of ENaC function in colon was impaired; and 3) NaCl-sensitive hypertension was substantially reduced in the presence of amiloride, a specific inhibitor of ENaC. Nedd4-2 null mice on a chronic high-salt diet showed cardiac hypertrophy and markedly depressed cardiac function. Overall, our results demonstrate that in vivo Nedd4-2 is a critical regulator of ENaC activity and BP. The absence of this gene is sufficient to produce salt-sensitive hypertension. This model provides an opportunity to further investigate mechanisms and consequences of this common disorder.
Animals, Blood Pressure/drug effects, Blood Pressure/physiology, Cardiomegaly/genetics, Cardiomegaly/metabolism, Disease Models, Animal, Endosomal Sorting Complexes Required for Transport, Epithelial Sodium Channel/metabolism, Hypertension/genetics, Hypertension/metabolism, Mice, Mice, Inbred C57BL, Mice, Knockout, Sodium Chloride, Dietary/pharmacology, Ubiquitin-Protein Ligases/genetics, Ubiquitin-Protein Ligases/metabolism
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