title: SGK1-dependent stimulation of intestinal SGLT1 activity by vitamin D.
abstract: The serum- and glucocorticoid-inducible kinase SGK1 has previously been shown to mediate the glucocorticoid-dependent stimulation of several intestinal transport systems including the electrogenic glucose transporter SGLT1. In squamous carcinoma cells, SGK1 expression is stimulated by 1,25(OH)₂D₃, the biologically active metabolite of vitamin D. The present study explored whether vitamin D influences the intestinal SGLT1 activity. Jejunal SGLT1 activity was determined by Ussing chamber experiments. Under a normal diet, the electrogenic glucose transport was similar in SGK1 knockout (sgk1 ( -/- )) and wild type mice (sgk1 ( +/+ )). Following a vitamin D-rich diet (14 days 10,000 I.U. vitamin D), the SGK1 transcript levels as well as the SGLT1 protein abundance were increased in sgk1(+/+) mice. Moreover, SGLT1 activity was increased in sgk1(+/+) mice but not in sgk1(-/-) mice following a vitamin D-rich diet. Furthermore, an oral glucose load was followed by an increase in the plasma glucose concentration to significantly higher values in sgk1(+/+) mice treated with a vitamin D-rich diet than in untreated sgk1(+/+) mice. In conclusion, vitamin D treatment upregulates the expression of SGK1, which in turn enhances SGLT1 activity.
authors: Department of Physiology, University of Tübingen, Tübingen, Germany.
authors: Rexhep
authors: R
authors: Rexhepaj
authors: Ioana
authors: I
authors: Alesutan
authors: Shuchen
authors: S
authors: Gu
authors: Lisann
authors: L
authors: Pelzl
authors: Melanie
authors: M
authors: Eichenmüller
authors: Ganesh
authors: G
authors: Pathare
authors: Michael
authors: M
authors: Föller
authors: Dietmar
authors: D
authors: Kuhl
authors: Florian
authors: F
authors: Lang
mesh_terms: D000818:Animals; D018938:Caco-2 Cells; D004032:Diet; D005947:Glucose / Q000378:metabolism; D005951:Glucose Tolerance Test; D006801:Humans; D017874:Immediate-Early Proteins / Q000235:genetics / Q000378:metabolism*; D007413:Intestinal Mucosa / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D051269:Sodium-Glucose Transporter 1 / Q000235:genetics / Q000378:metabolism*; D014807:Vitamin D / Q000008:administration & dosage*; D000099184:Serum-Glucocorticoid Regulated Kinases
chemical_list: D005947:Glucose; D017874:Immediate-Early Proteins; D017346:Protein Serine-Threonine Kinases; D051269:Sodium-Glucose Transporter 1; D014807:Vitamin D; D000099184:Serum-Glucocorticoid Regulated Kinases