Transcriptional regulation of the human NaPi-IIb cotransporter by EGF in Caco-2 cells involves c-myb

Hua Xu, Michael Inouye, Eric R. Hines, James F. Collins, Fayez K Ghishan

Research output: Contribution to journalArticle

38 Citations (Scopus)

Abstract

The type IIb sodium-phosphate (NaPi-IIb) cotransporter mediates intestinal phosphate absorption. Previous work in our laboratory has shown that EGF inhibited NaPiIIb cotransporter expression through transcriptional regulation. To understand this regulation, progressively shorter human NaPi-IIb promoter constructs were used to define the EGF response region, and gel mobility shift assays (GMSAs) were used to characterize DNA-protein interactions. Promoter analysis determined that the EGF response region was located between -784 and -729 base pair (bp) of the promoter. GMSAs and overexpression studies revealed an interaction between this promoter region and c-myb transcription factor. Inhibition of EGF receptor activation restored promoter function. Further studies suggested that MAPK, PKC, and/or PKA pathways are involved in this regulation. In conclusion, these studies suggest that EGF decreases human NaPi-IIb gene expression by modifying the c-myb protein such that it inhibits transcriptional activation. We further conclude that this downregulation of promoter function is mediated by EGF-activated PKC/PKA and MAPK pathways. This is the first study that demonstrates involvement of c-myb in the regulation of intestinal nutrient absorption.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Cell Physiology
Volume284
Issue number5 53-5
StatePublished - May 1 2003

Fingerprint

Caco-2 Cells
Epidermal Growth Factor
Intestinal Absorption
Electrophoretic Mobility Shift Assay
Proto-Oncogene Proteins c-myb
Assays
Gels
Chemical activation
Epidermal Growth Factor Receptor
Genetic Promoter Regions
Gene expression
Base Pairing
Transcriptional Activation
Nutrients
Transcription Factors
Down-Regulation
Phosphates
Gene Expression
Food
DNA

Keywords

  • Epidermal growth factor
  • Type IIb sodium-phosphate cotransporter

ASJC Scopus subject areas

  • Clinical Biochemistry
  • Cell Biology
  • Physiology

Cite this

Transcriptional regulation of the human NaPi-IIb cotransporter by EGF in Caco-2 cells involves c-myb. / Xu, Hua; Inouye, Michael; Hines, Eric R.; Collins, James F.; Ghishan, Fayez K.

In: American Journal of Physiology - Cell Physiology, Vol. 284, No. 5 53-5, 01.05.2003.

Research output: Contribution to journalArticle

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AU - Collins, James F.

AU - Ghishan, Fayez K

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