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XB-ART-41190
J Biol Chem 2010 May 28;28522:16504-12. doi: 10.1074/jbc.M109.072140.
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Inhibition of Na+-taurocholate Co-transporting polypeptide-mediated bile acid transport by cholestatic sulfated progesterone metabolites.

Abu-Hayyeh S , Martinez-Becerra P , Sheikh Abdul Kadir SH , Selden C , Romero MR , Rees M , Marschall HU , Marin JJ , Williamson C .


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Sulfated progesterone metabolite (P4-S) levels are raised in normal pregnancy and elevated further in intrahepatic cholestasis of pregnancy (ICP), a bile acid-liver disorder of pregnancy. ICP can be complicated by preterm labor and intrauterine death. The impact of P4-S on bile acid uptake was studied using two experimental models of hepatic uptake of bile acids, namely cultured primary human hepatocytes (PHH) and Na(+)-taurocholate co-transporting polypeptide (NTCP)-expressing Xenopus laevis oocytes. Two P4-S compounds, allopregnanolone-sulfate (PM4-S) and epiallopregnanolone-sulfate (PM5-S), reduced [(3)H]taurocholate (TC) uptake in a dose-dependent manner in PHH, with both Na(+)-dependent and -independent bile acid uptake systems significantly inhibited. PM5-S-mediated inhibition of TC uptake could be reversed by increasing the TC concentration against a fixed PM5-S dose indicating competitive inhibition. Experiments using NTCP-expressing Xenopus oocytes confirmed that PM4-S/PM5-S are capable of competitively inhibiting NTCP-mediated uptake of [(3)H]TC. Total serum PM4-S + PM5-S levels were measured in non-pregnant and third trimester pregnant women using liquid chromatography-electrospray tandem mass spectrometry and were increased in pregnant women, at levels capable of inhibiting TC uptake. In conclusion, pregnancy levels of P4-S can inhibit Na(+)-dependent and -independent influx of taurocholate in PHH and cause competitive inhibition of NTCP-mediated uptake of taurocholate in Xenopus oocytes.

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Species referenced: Xenopus laevis
Genes referenced: slc10a1

References [+] :
Arrese, Down-regulation of the Na+/taurocholate cotransporting polypeptide during pregnancy in the rat. 2003, Pubmed