RT Journal Article
SR Electronic
T1 Modification of OATP2B1-Mediated Transport by Steroid Hormones
JF Molecular Pharmacology
JO Mol Pharmacol
FD American Society for Pharmacology and Experimental Therapeutics
SP 1735
OP 1741
DO 10.1124/mol.106.026450
VO 70
IS 5
A1 Markus Grube
A1 Kathleen Köck
A1 Susanne Karner
A1 Sebastian Reuther
A1 Christoph A. Ritter
A1 Gabriele Jedlitschky
A1 Heyo K. Kroemer
YR 2006
UL http://molpharm.aspetjournals.org/content/70/5/1735.abstract
AB The family of the organic anion transporting polypeptides forms an increasing group of uptake transport proteins with a wide substrate spectrum. Although the expression of some members of this group, such as organic anion transporting polypeptide (OATP)-A or C, is limited to special tissues (such as liver or brain), the organic anion transporting polypeptide 2B1 (OATPB/SLCO2B1) is expressed in many organs, including liver, placenta, mammary gland, brain, and intestine. However, little is known about its function in those tissues because only a limited number of compounds, such as dehydroepiandrosterone-sulfate (DHEAS) and estrone-3-sulfate (E3S), have been characterized as OATP2B1 substrates. To further elucidate the role of OATP2B1 on steroid transport, we examined the influence of steroid hormones on OATP2B1-mediated E3S and DHEAS uptake using OATP2B1-overexpressing Madin-Darby canine kidney II cells. We identified unconjugated androgens (e.g., testosterone) as potent inhibitors for OATP2B1. In contrast, gestagenes such as progesterone enhanced E3S uptake in a concentration-dependent manner to up to 300% of the control, accompanied by a significant decrease in the OATP2B1 Km value for E3S (control, Km = 14 μM; in the presence of 31.6 μM progesterone, Km = 3.6 μM). Moreover, we demonstrated that testosterone and progesterone are not substrates of OATP2B1, indicating an allosteric mechanism for the observed effects. Furthermore, we showed that progesterone enhances the OATP2B1-dependent pregnenolone sulfate transport. Taken together, the results indicate functional modification of OATP2B1-mediated E3S and DHEAS as well as pregnenolone sulfate transport through steroid hormones such as progesterone. These effects can have physiological consequences for the organ-specific uptake of steroids. The American Society for Pharmacology and Experimental Therapeutics