Does the early aldosterone-induced SGK1 play a role in early Kaliuresis?

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Version: Final published version
License: CC BY 4.0
Serval ID
serval:BIB_90DE4FDA5B15
Type
Article: article from journal or magazin.
Collection
Publications
Institution
Title
Does the early aldosterone-induced SGK1 play a role in early Kaliuresis?
Journal
Physiological reports
Author(s)
Al-Qusairi L., Basquin D., Stifanelli M., Welling P.A., Staub O.
ISSN
2051-817X (Electronic)
ISSN-L
2051-817X
Publication state
Published
Issued date
02/2022
Peer-reviewed
Oui
Volume
10
Number
4
Pages
e15188
Language
english
Notes
Publication types: Journal Article ; Research Support, Non-U.S. Gov't
Publication Status: ppublish
Abstract
Urinary K <sup>+</sup> potassium excretion rapidly increases after a potassium-rich meal. The early aldosterone-induced sgk1 gene (encoding serum and glucocorticoid-induced kinase 1), activates potassium clearance, but the role of this kinase in the early activation of K <sup>+</sup> secretion has not been clearly defined. Here, we challenged inducible renal-tubule-specific Sgk1 <sup>Pax8</sup> <sup>/</sup> <sup>LC1</sup> knockout mice with an acute high-potassium load (HK:5%K <sup>+</sup> ) and compared the physiological and molecular responses to control mice. We observe that urinary excretion after a K <sup>+</sup> load over the first 3 h is not dependent on SGK1 but is coincident with the rapid dephosphorylation of the Na <sup>+</sup> ,Cl <sup>-</sup> -cotransporter (NCC) to increase distal salt delivery. Molecular analyses indicate that whereas SGK1-mediated phosphorylation of the ubiquitin-protein ligase NEDD4-2 begins to increase by 3h, SGK1-dependent proteolytic activation of ENaC only becomes detectable after 6 h of HK intake. Consistent with SGK1-dependent ENaC activation via inhibition of NEDD4-2-mediated ubiquitylation, Sgk1 <sup>Pax8</sup> <sup>/</sup> <sup>LC1</sup> mice are unable to efficiently inhibit NEDD4-2 or increase ENaC cleavage after 6 h of HK. Nevertheless, no defect in acute K <sup>+</sup> balance was detected in the mutant mice after 6 h of HK. Moreover, we found that Sgk1 <sup>Pax8</sup> <sup>/</sup> <sup>LC1</sup> mice reduce NCC phosphorylation and NCC-mediated salt absorption to a greater extent than control mice after a K <sup>+</sup> load, promoting increased amiloride-sensitive Na <sup>+</sup> -reabsorption via ENaC to maintain adequate kaliuresis. Together, these data indicate that: (a) during the early 3 h of HK intake, K <sup>+</sup> excretion is SGK1-independent even under an extreme K <sup>+</sup> challenge, (b) shortly after, SGK1 inhibits NEDD4-2 and activates ENaC to stimulate K <sup>+</sup> -secretion, (c) SGK1-dependent phosphorylation of NCC occurs, acting more likely as a brake pedal to prevent excessive K <sup>+</sup> loss.
Keywords
Aldosterone, Animals, Epithelial Sodium Channels/genetics, Mice, Nedd4 Ubiquitin Protein Ligases/genetics, Potassium/metabolism, Sodium/metabolism, Sodium Chloride, Dietary/metabolism, Solute Carrier Family 12, Member 3/genetics
Pubmed
Web of science
Open Access
Yes
Create date
07/03/2022 12:22
Last modification date
23/01/2024 8:30
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