Regulation of intestinal NaPi-IIb cotransporter gene expression by estrogen

Hua Xu, Jennifer K. Uno, Michael Inouye, Liping Xu, Jason B. Drees, James F. Collins, Fayez K Ghishan

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Abstract

The current experiments were designed to study the effect of β-estradiol on type IIb sodium-coupled phosphate (NaPi-IIb) cotransporter gene expression. Uptake studies with intestinal brush-border membrane vesicles (BBMV) showed that estrogen treatment increased sodium-dependent phosphate absorption by ∼45% in rat intestine. Northern blot analysis indicated that NaPi-IIb mRNA expression was increased by ∼50% after estrogen treatment. Western blot analysis also detected an increase in BBMV NaPi-IIb protein expression in estrogen-treated rats. In human intestinal Caco-2 cells, NaPi-IIb mRNA abundance was increased ∼60% after estrogen treatment, and this increase could be abolished by inhibition of gene transcription. Transfection studies with human NaPi-IIb promoter reporter constructs showed that the promoter was responsive to estrogen treatment. These studies demonstrate for the first time that estrogen stimulates intestinal sodium-dependent phosphate absorption in female rats. This stimulation is associated with increased NaPi-IIb mRNA and protein expression. Thus the effect of estrogen on intestinal Pi absorption may be partially due to activation of NaPi-IIb gene transcription.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Gastrointestinal and Liver Physiology
Volume285
Issue number6 48-6
Publication statusPublished - Dec 2003

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Keywords

  • Caco-2 cells
  • Rat intestine
  • SLC34A2
  • Type IIb sodium-phosphate cotransporter

ASJC Scopus subject areas

  • Gastroenterology
  • Physiology

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