title: Intestinal function of gene-targeted mice lacking serum- and glucocorticoid-inducible kinase 1.
abstract: In vitro experiments have revealed the ability of serum- and glucocorticoid-inducible kinase 1 (SGK1) to stimulate intestinal Na(+)-coupled glucose cotransporter 1 (SGLT1) and intestinal Na(+)/H(+) exchanger 3 (NHE3). The present study explored the contribution of SGK1 to the regulation of intestinal transport in vivo. SGK1 transcript levels were determined by real-time PCR and glucose-induced currents (I(g)) reflecting SGLT1 activity by Ussing chamber experiments. BCECF fluorescence was utilized for the determination of Na(+)-dependent pH recovery from an ammonium pulse (DeltapH(NHE)) reflecting NHE activity. As a result, intestinal SGK1 transcript levels were significantly enhanced by a 4-day treatment with 10 microg.mg body wt(-1).day(-1) dexamethasone (Dex). I(g) was, under control conditions, virtually identical in sgk1 knockout mice (sgk1(-/-)) and their wild type littermates (sgk1(+/+)). A 4-day treatment with Dex, however, increased I(g) approximately threefold in sgk1(+/+) mice but not in sgk1(-/-) mice. DeltapH(NHE) was similar in sgk1(-/-) and sgk1(+/+) mice before treatment. Dex increased DeltapH(NHE) approximately threefold in sgk1(+/+) mice and approximately twofold in sgk1(-/-)mice, an effect significantly blunted in the presence of the specific NHE3 blocker S-3226 (10 microM). According to Western blot analysis, Dex significantly enhanced SGLT1 and NHE3 protein abundance in brush-border membranes of sgk1(+/+) mice but not of sgk1(-/-)mice. In conclusion, basic functions of SGLT1 and NHE3 in the intestine do not require stimulation by SGK1. However, the effects of glucocorticoids on SGLT1 are fully, and on NHE3 partially, dependent on SGK1.
authors.affiliation: Department of Physiology, University of Tübingen, Germany. florian.lang@uni-tuebingen.de
authors.forename: Florian
authors.initials: F
authors.lastname: Grahammer
authors.forename: Guido
authors.initials: G
authors.lastname: Henke
authors.forename: Ciprian
authors.initials: C
authors.lastname: Sandu
authors.forename: Rexhep
authors.initials: R
authors.lastname: Rexhepaj
authors.forename: Azeemudeen
authors.initials: A
authors.lastname: Hussain
authors.forename: Björn
authors.initials: B
authors.lastname: Friedrich
authors.forename: Teut
authors.initials: T
authors.lastname: Risler
authors.forename: Marco
authors.initials: M
authors.lastname: Metzger
authors.forename: Lothar
authors.initials: L
authors.lastname: Just
authors.forename: Thomas
authors.initials: T
authors.lastname: Skutella
authors.forename: Peer
authors.initials: P
authors.lastname: Wulff
authors.forename: Dietmar
authors.initials: D
authors.lastname: Kuhl
authors.forename: Florian
authors.initials: F
authors.lastname: Lang
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D018390:Gene Targeting; D017874:Immediate-Early Proteins / Q000378:metabolism*; D007422:Intestines / Q000502:physiology*; D051379:Mice; D008822:Mice, Transgenic; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D051269:Sodium-Glucose Transporter 1 / Q000235:genetics / Q000378:metabolism*; D000074083:Sodium-Hydrogen Exchanger 3; D017923:Sodium-Hydrogen Exchangers / Q000378:metabolism*; D000099184:Serum-Glucocorticoid Regulated Kinases
chemical_list: D017874:Immediate-Early Proteins; D017346:Protein Serine-Threonine Kinases; D051269:Sodium-Glucose Transporter 1; D000074083:Sodium-Hydrogen Exchanger 3; D017923:Sodium-Hydrogen Exchangers; D000099184:Serum-Glucocorticoid Regulated Kinases; C495675:Slc5a1 protein, mouse; C000613386:Slc9a3 protein, mouse