Aldosterone induces rapid apical translocation of ENaC in early portion of renal collecting system: possible role of SGK
Details
Serval ID
serval:BIB_7F99A1948989
Type
Article: article from journal or magazin.
Collection
Publications
Institution
Title
Aldosterone induces rapid apical translocation of ENaC in early portion of renal collecting system: possible role of SGK
Journal
American Journal of Physiology. Renal Physiology
ISSN
0363-6127
Publication state
Published
Issued date
04/2001
Peer-reviewed
Oui
Volume
280
Number
4
Pages
F675-82
Notes
In Vitro
Journal Article
Research Support, Non-U.S. Gov't --- Old month value: Apr
Journal Article
Research Support, Non-U.S. Gov't --- Old month value: Apr
Abstract
Aldosterone controls sodium reabsorption and potassium secretion in the aldosterone-sensitive distal nephron (ASDN). Although clearance measurements have shown that aldosterone induces these transports within 30--60 min, no early effects have been demonstrated in vivo at the level of the apical epithelial sodium channel (ENaC), the main effector of this regulation. Here we show by real-time RT-PCR and immunofluorescence that an aldosterone injection in adrenalectomized rats induces alpha-ENaC subunit expression along the entire ASDN within 2 h, whereas beta- and gamma-ENaC are constitutively expressed. In the proximal ASDN portions only, ENaC is shifted toward the apical cellular pole and the apical plasma membrane within 2 and 4 h, respectively. To address the question of whether the early aldosterone-induced serum and glucocorticoid-regulated kinase (SGK) might mediate this apical shift of ENaC, we analyzed SGK induction in vivo. Two hours after aldosterone, SGK was highly induced in all segment-specific cells of the ASDN, and its level decreased thereafter. In Xenopus laevis oocytes, SGK induced ENaC activation and surface expression by a kinase activity-dependent mechanism. In conclusion, the rapid in vivo accumulation of SGK and alpha-ENaC after aldosterone injection takes place along the entire ASDN, whereas the translocation of alpha,beta,gamma-ENaC to the apical plasma membrane is restricted to its proximal portions. Results from oocyte experiments suggest the hypothesis that a localized activation of SGK may play a role in the mediation of ENaC translocation.
Keywords
Aldosterone/*pharmacology
Animals
Biological Transport/drug effects/physiology
Cell Membrane/metabolism
Cell Polarity/physiology
Epithelial Sodium Channel
Gene Expression/drug effects/physiology
Immediate-Early Proteins
Kidney Tubules, Collecting/drug effects/*enzymology
Male
*Nuclear Proteins
Oocytes/physiology
Patch-Clamp Techniques
Protein-Serine-Threonine Kinases/genetics/*metabolism
RNA, Messenger/analysis
Rats
Rats, Wistar
Sodium/metabolism
Sodium Channels/genetics/*metabolism
Xenopus laevis
Pubmed
Web of science
Create date
24/01/2008 13:00
Last modification date
20/08/2019 14:40