A naturally occurring human Nedd4-2 variant displays impaired ENaC regulation in Xenopus laevis oocytes

Details

Serval ID
serval:BIB_DBE583EEBA79
Type
Article: article from journal or magazin.
Collection
Publications
Institution
Title
A naturally occurring human Nedd4-2 variant displays impaired ENaC regulation in Xenopus laevis oocytes
Journal
American Journal of Physiology. Renal Physiology
Author(s)
Fouladkou  F., Alikhani-Koopaei  R., Vogt  B., Flores  S. Y., Malbert-Colas  L., Lecomte  M. C., Loffing  J., Frey  F. J., Frey  B. M., Staub  O.
ISSN
0363-6127 (Print)
Publication state
Published
Issued date
09/2004
Volume
287
Number
3
Pages
F550-61
Notes
Journal Article
Research Support, Non-U.S. Gov't --- Old month value: Sep
Abstract
The epithelial Na(+) channel (ENaC) is regulated by the ubiquitin-protein ligase Nedd4-2 via interaction with ENaC PY-motifs. These PY-motifs are mutated/deleted in Liddle's syndrome, resulting in elevated Na(+) reabsorption and hypertension explained partly by impaired ENaC-Nedd4-2 interaction. We hypothesized that Nedd4-2 is a susceptibility gene for hypertension and screened 856 renal patients and healthy controls for mutations in a subset of exons of the human Nedd4-2 gene that are relevant for ENaC regulation by PCR/single-strand conformational polymorphism. Several variants were identified, and one nonsynonymous mutation (Nedd4-2-P355L) was further characterized. This mutation next to the 3' donor site of exon 15 does not affect in vitro splicing of Nedd4-2 mRNA. However, in the Xenopus oocyte expression system, Nedd4-2-P355L-dependent ENaC inhibition was weaker compared with the wild type (Nedd4-2-WT), and this difference depended on the presence of intact PY-motifs on ENaC. This could not be explained by the amount of wild type or mutant Nedd4-2 coimmunoprecipitating with ENaC. When the phosphorylation level of human Nedd4-2 Ser(448) (known to be phosphorylated by the Sgk1 kinase) was determined with a specific anti-pSer(448) antibody, we observed stronger basal phosphorylation of Nedd4-2-P355L. Both the phosphorylation level and the accompanying amiloride-sensitive Na(+) currents could be further enhanced to approximately the same levels by coexpressing Sgk1. In addition, the role of the two other putative Sgk1 phosphorylation sites (S342 and T367) appears also to be affected by the P355L mutation. The differential phosphorylation status between wild-type and mutant Nedd4-2 provides an explanation for the different potential to inhibit ENaC activity.
Keywords
Adolescent Adult Aged Aged, 80 and over Animals Down-Regulation Epithelial Sodium Channel Female Homeostasis Humans Immediate-Early Proteins Kidney Failure, Chronic/*genetics/metabolism Male Middle Aged *Nuclear Proteins Oocytes Phosphorylation Point Mutation Polymorphism, Single-Stranded Conformational Protein Structure, Tertiary Protein-Serine-Threonine Kinases/metabolism RNA Splicing Serine/metabolism Sodium Channels/*metabolism Ubiquitin/metabolism Ubiquitin-Protein Ligases/chemistry/*genetics/*metabolism Xenopus laevis
Pubmed
Web of science
Create date
24/01/2008 13:03
Last modification date
20/08/2019 16:00
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