sigma Receptor ligand-induced up-regulation of the H(+)/peptide transporter PEPT1 in the human intestinal cell line Caco-2.
We determined the effects of (+)pentazocine, a selective sigma(1) ligand, on the uptake of glycylsarcosine (Gly-Sar) in the human intestinal cell line Caco-2 which expresses the low affinity/high capacity peptide transporter PEPT1. Confluent Caco-2 cells were treated with various concentrations of (+)pentazocine for desired time (mostly 24 hr). The activity of PEPT1 was assessed by measuring the uptake of [(14)C]Gly-Sar in the presence of a H(+) gradient. (+)Pentazocine increased the uptake of [(14)C]Gly-Sar mediated by PEPT1 in a concentration- and time-dependent manner. Kinetic analyses have indicated that (+)pentazocine increased the maximal velocity (V(max)) for Gly-Sar uptake in Caco-2 cells without affecting the Michaelis-Menten constant (K(t)). In addition, semi-quantitative RT-PCR revealed that treatment of (+)pentazocine increased PEPT1 mRNA in Caco-2 cells in a concentration-dependent manner. These data suggest that sigma(1) receptor ligand (+)pentazocine up-regulates PEPT1 in Caco-2 cells at the level of increased mRNA, causing an increase in the density of the transporter protein in the cell membrane.
Fujita
T
T
Department of Biopharmaceutical Sciences, Kyoto Pharmaceutical University, Yamashina-ku, Kyoto, 607-8414, Japan. fujita@mb.kyoto-phu.ac.jp
Majikawa
Y
Y
Umehisa
S
S
Okada
N
N
Yamamoto
A
A
Ganapathy
V
V
Leibach
F H
FH
D001483:Base Sequence; D001693:Biological Transport, Active / Q000187:drug effects; D018938:Caco-2 Cells; D002352:Carrier Proteins / Q000235:genetics* / Q000378:metabolism*; D017931:DNA Primers / Q000235:genetics; D004151:Dipeptides / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D008024:Ligands; D010423:Pentazocine / Q000494:pharmacology; D000074011:Peptide Transporter 1; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017480:Receptors, sigma / Q000378:metabolism*; D027981:Symporters; D015854:Up-Regulation / Q000187:drug effects
D002352:Carrier Proteins; D017931:DNA Primers; D004151:Dipeptides; D008024:Ligands; D000074011:Peptide Transporter 1; D012333:RNA, Messenger; D017480:Receptors, sigma; C082186:SLC15A1 protein, human; D027981:Symporters; C004194:glycylsarcosine; D010423:Pentazocine