Characteristics of thiamine uptake by the BeWo human trophoblast cell line.
Little is known concerning the mechanisms responsible for the transplacental transfer of thiamine. So, the aim of this work was to characterize the placental uptake of thiamine from the maternal circulation, by determining the characteristics of 3H-thiamine uptake by a human trophoblast cell line (BeWo). Uptake of (3)H-thiamine (50-100 nM) by BeWo cells was: 1) temperature-dependent and energy-independent; 2) pH-dependent (uptake increased as the extracellular medium pH decreased); 3) Na(+)-dependent and Cl(-)-independent; 4) not inhibited by the thiamine structural analogs amprolium, oxythiamine and thiamine pyrophosphate; 5) inhibited by the unrelated organic cations guanidine, N-methylnicotinamide, tetraethylammonium, clonidine and cimetidine; 6) inhibited by the organic cation serotonin, and by two selective inhibitors of the serotonin plasmalemmal transporter (hSERT), fluoxetine and desipramine. We conclude that (3)H-thiamine uptake by BeWo cells seems to occur through a process distinct from thiamine transporter-1 (hThTr-1) and thiamine transporter-2 (hThTr-2). Rather, it seems to involve hSERT. Moreover, chronic (48 h) exposure of cells to caffeine (1 microM) stimulated and chronic exposure to xanthohumol and iso-xanthohumol (1 and 0.1 microM, respectively) inhibited (3)H-thiamine uptake, these effects being not mediated through modulation of the expression levels of either hThTr-1 or hSERT mRNA.
Keating
Elisa
E
Department of Biochemistry (U38-FCT), Faculty of Medicine, University of Porto, 4200-319 Porto, Portugal.
Lemos
Clara
C
Azevedo
Isabel
I
Martel
Fátima
F
D001692:Biological Transport / Q000187:drug effects; D002110:Caffeine / Q000494:pharmacology; D045744:Cell Line, Tumor; D021961:Cell Membrane Structures; D000431:Ethanol / Q000378:metabolism / Q000494:pharmacology; D005260:Female; D005419:Flavonoids / Q000494:pharmacology; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases / Q000235:genetics; D006801:Humans; D006863:Hydrogen-Ion Concentration; D026901:Membrane Transport Proteins / Q000235:genetics; D010636:Phenols / Q000494:pharmacology; D010920:Placenta / Q000378:metabolism; D059808:Polyphenols; D011247:Pregnancy; D050486:Serotonin Plasma Membrane Transport Proteins / Q000235:genetics; D013696:Temperature; D013806:Theophylline / Q000494:pharmacology; D013831:Thiamine / Q000378:metabolism*; D014327:Trophoblasts / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*
D005419:Flavonoids; D026901:Membrane Transport Proteins; D010636:Phenols; D059808:Polyphenols; C120043:SLC19A2 protein, human; C492291:SLC19A3 protein, human; D050486:Serotonin Plasma Membrane Transport Proteins; D002110:Caffeine; D000431:Ethanol; D013806:Theophylline; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases; D013831:Thiamine