Epidermal growth factor inhibits glycylsarcosine transport and hPepT1 expression in a human intestinal cell line

C U Nielsen, J Amstrup, B Steffansen, S Frokjaer, Birger Brodin

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    Abstract

    The human intestinal cell line Caco-2 was used as a model system to study the effects of epidermal growth factor (EGF) on peptide transport. EGF decreased apical-to-basolateral fluxes of [(14)C]glycylsarcosine ([(14)C]Gly-Sar) up to 50.2 +/- 3.6% (n = 6) of control values. Kinetic analysis of the fluxes showed that maximal flux (V(max)) of transepithelial transport decreased from 3.00 +/- 0.17 nmol x cm(-2) x min(-1) in control cells to 0.50 +/- 0.07 nmol x cm(-2) x min(-1) in cells treated with 5 ng/ml EGF (n = 6, P <0.01). The apparent Michaelis-Menten constant (K(m)) was 2.71 +/- 0.31 mM (n = 6) in control cells and 1.89 +/- 0.28 mM (n = 6, not significantly different from control) in EGF-treated cells. Similarly, apical uptake of [(14)C]Gly-Sar decreased in cells treated with EGF, with an ED(50) value of 0.36 +/- 0.06 ng/ml (n = 6) EGF and a maximal inhibition of 80 +/- 0.02% (n = 6). V(max) decreased from 2.61 +/- 0.4 to 1.06 +/- 0.1 nmol x cm(-2) x min(-1) (n = 3, P <0.05), whereas K(m) remained constant. Basolateral Gly-Sar uptake showed no changes in V(max) or K(m) after EGF treatment (n = 3). RT-PCR showed a decrease in hPepT1 mRNA (using glucose-6-phosphate dehydrogenase mRNA as control) in cells treated with EGF. Western blotting indicated a decrease in hPepT1 protein in cell lysates. We conclude that EGF treatment decreases Gly-Sar transport in Caco-2 cells by decreasing the number of peptide transporter molecules in the apical membrane.
    Original languageEnglish
    JournalAmerican Journal of Physiology: Gastrointestinal and Liver Physiology
    Volume281
    Issue number1
    Pages (from-to)G191-9
    ISSN0193-1857
    Publication statusPublished - 2001

    Keywords

    • Biological Transport
    • Caco-2 Cells
    • Carbon Radioisotopes
    • Carrier Proteins
    • Dipeptides
    • Dose-Response Relationship, Drug
    • Epidermal Growth Factor
    • Gene Expression
    • Humans
    • Immunohistochemistry
    • Intestinal Mucosa
    • Microscopy, Confocal
    • RNA, Messenger
    • Symporters

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