Localization of the sulfate/anion exchanger in the rat liver.
Although the sulfate/anion transporter (sat-1; SLC26A1) was isolated from a rat liver cDNA library by expression cloning, localization of sat-1 within the liver and its contribution to the transport of sulfate and organo sulfates have remained unresolved. In situ hybridization and immunohistochemical studies were undertaken to demonstrate the localization of sat-1 in liver tissue. RT-PCR studies on isolated hepatocytes and liver endothelial and stellate cells in culture were performed to test for the presence of sat-1 in these cells. In sulfate uptake and efflux experiments, the substrate specificity of sat-1 was evaluated. Sat-1 mRNA was found in hepatocytes and endothelial cells. Sat-1 protein was localized in sinusoidal membranes and along the borders of hepatocytes. The canalicular region and bile capillaries were not stained. Sulfate uptake was only slightly affected by sulfamoyl diuretics or organo sulfates. Sulfate efflux from sat-1-expressing oocytes was enhanced in the presence of bicarbonate, indicating sulfate/bicarbonate exchange. Estrone sulfate was not transported by sat-1. Sat-1 may be responsible for the uptake of inorganic sulfate from the blood into hepatocytes to enable sulfation reactions. In hepatocytes and endothelial cells, sat-1 may also supply sulfate for proteoglycan synthesis.
Quondamatteo
Fabio
F
Abteilung Histologie, Georg August Universität Göttingen, Humboldtallee 23, Göttingen 37073, Germany.
Krick
Wolfgang
W
Hagos
Yohannes
Y
Krüger
Marie-Helen
MH
Neubauer-Saile
Katrin
K
Herken
Rainer
R
Ramadori
Giuliano
G
Burckhardt
Gerhard
G
Burckhardt
Birgitta C
BC
D026924:Amino Acid Transport System A / Q000032:analysis* / Q000502:physiology; D000818:Animals; D001639:Bicarbonates / Q000494:pharmacology; D019314:Dehydroepiandrosterone Sulfate / Q000493:pharmacokinetics; D042783:Endothelial Cells / Q000378:metabolism; D004970:Estrone / Q000031:analogs & derivatives / Q000378:metabolism; D022781:Hepatocytes / Q000378:metabolism; D008099:Liver / Q000737:chemistry* / Q000378:metabolism; D008297:Male; D051381:Rats; D013431:Sulfates / Q000378:metabolism*; D014494:Unithiol / Q000494:pharmacology
D026924:Amino Acid Transport System A; D001639:Bicarbonates; C486716:Slc38a1 protein, rat; D013431:Sulfates; D004970:Estrone; D014494:Unithiol; D019314:Dehydroepiandrosterone Sulfate; C017296:estrone sulfate