Digestive Diseases and Sciences

, Volume 53, Issue 8, pp 2113–2125

In Human Entrocytes, GLN Transport and ASCT2 Surface Expression Induced by Short-Term EGF are MAPK, PI3K, and Rho-Dependent

Authors

    • Department of SurgerySchool of Medicine and Dentistry, University of Rochester
  • Harry C. Sax
    • Department of SurgerySchool of Medicine and Dentistry, University of Rochester
    • Department of SurgeryThe Miriam Hospital
  • Liana Toia
    • Department of SurgerySchool of Medicine and Dentistry, University of Rochester
Original Paper

DOI: 10.1007/s10620-007-0120-y

Cite this article as:
Avissar, N.E., Sax, H.C. & Toia, L. Dig Dis Sci (2008) 53: 2113. doi:10.1007/s10620-007-0120-y

Abstract

Glutamine, a key nutrient for the enterocyte, is transported among other proteins by ASCT2. Epidermal growth factor (EGF) augments intestinal adaptation. We hypothesized that short-term treatment of human enterocytes with EGF enhances glutamine transport by increasing membranal ASCT2. To elucidate EGF-induced mechanisms, monolayers of C2BBe1 w/wo siRho transfection were treated w/wo EGF and w/wo tyrphostin AG1478 (AG1478), wortmanin, or PD98059. Total and system-specific 3H-glutamine transports were determined w/wo 5 mmol/l amino acid inhibitors. Total and membranal ASCT2 proteins were measured by Westerns. EGF doubled glutamine transport by increasing B0/ASCT2 and B0,+ activities. Despite the doubling of membranal ASCT2 protein with EGF treatment, total ASCT2 did not change. The increases in B0/ASCT2 activity and ASCT2 protein were eliminated by AG1478, PD98059, wortmanin, and siRho, while transport by B0,+ was inhibited only by PD98059 and siRho. Thus, differential pathways are involved in EGF-induced increase in B0/ASCT2 glutamine transport and membranal ASCT2 compared to those involved in B0,+ activity.

Keywords

Intestinal cell lineGlutamine transportEpidermal growth factorSignal-transduction pathwaysASCT2 surface expression

Abbreviations

Gln

Glutamine

EGF

Epidermal growth factor

C2

C2BBe1

PI3K

Phosphatidyl inositol-3 kinase

Erk

Extracellular regulated kinase

EGFR

EGF receptor

AG1478

Tyrphostin AG1478

AG9

Tyrphostin AG9

PBS

Phosphate-buffered saline

PPI

Protease and phosphatase inhibitors

PMSF

Phenyl methyl sulfonyl fluoride

DTT

Dithiothreitol

MAPK

Mitogen-activated protein kinase

BPB

Bromphenol blue

OAT3

Organic anion transporter 3

Copyright information

© Springer Science+Business Media, LLC 2007