In human entrocytes, GLN transport and ASCT2 surface expression induced by short-term EGF are MAPK, PI3K, and Rho-dependent.
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 C2(BBe)1 w/wo siRho transfection were treated w/wo EGF and w/wo tyrphostin AG1478 (AG1478), wortmanin, or PD98059. Total and system-specific (3)H-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 B(0)/ASCT2 and B(0,+) activities. Despite the doubling of membranal ASCT2 protein with EGF treatment, total ASCT2 did not change. The increases in B(0)/ASCT2 activity and ASCT2 protein were eliminated by AG1478, PD98059, wortmanin, and siRho, while transport by B(0,+) was inhibited only by PD98059 and siRho. Thus, differential pathways are involved in EGF-induced increase in B(0)/ASCT2 glutamine transport and membranal ASCT2 compared to those involved in B(0,+) activity.
D026962:Amino Acid Transport System ASC / Q000378:metabolism*; D000730:Androstadienes / Q000494:pharmacology; D015153:Blotting, Western; D018938:Caco-2 Cells; D002462:Cell Membrane / Q000378:metabolism; D020895:Enterocytes / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D004815:Epidermal Growth Factor / Q000378:metabolism*; D066246:ErbB Receptors / Q000037:antagonists & inhibitors / Q000378:metabolism; D048049:Extracellular Signal-Regulated MAP Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D005419:Flavonoids / Q000494:pharmacology; D005973:Glutamine / Q000378:metabolism*; D006801:Humans; D015778:Minor Histocompatibility Antigens; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D021381:Protein Transport; D017027:Protein Tyrosine Phosphatases / Q000037:antagonists & inhibitors / Q000378:metabolism; D011799:Quinazolines; D034622:RNA Interference; D015398:Signal Transduction / Q000187:drug effects; D012964:Sodium / Q000378:metabolism; D013997:Time Factors; D020032:Tyrphostins / Q000494:pharmacology; D015854:Up-Regulation; D000077191:Wortmannin; D020741:rho GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*
D026962:Amino Acid Transport System ASC; D000730:Androstadienes; D004815:Epidermal Growth Factor; D066246:ErbB Receptors; D048049:Extracellular Signal-Regulated MAP Kinases; D005419:Flavonoids; D005973:Glutamine; D015778:Minor Histocompatibility Antigens; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D047428:Protein Kinase Inhibitors; D017027:Protein Tyrosine Phosphatases; D011799:Quinazolines; D012964:Sodium; D020032:Tyrphostins; D000077191:Wortmannin; D020741:rho GTP-Binding Proteins; C420506:SLC1A5 protein, human; C101044:RTKI cpd; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one