Identification, expression, and functional characterization of full-length and splice variants of murine organic anion transporting polypeptide 1b2.
The family of organic anion transporting polypeptides (OATPs) plays an important role in mediating the cellular uptake of numerous endogenous and exogenous compounds. Members of this family include human OATP1B1 and OATP1B3, which have been widely studied and shown to be involved in the hepatic uptake of hormones, bile acids, and many clinically used drugs. However, little is known about the murine orthologue, Oatp1b2. We determined expression of mouse oatp1b2 mRNA and protein using real-time PCR and Western blot analysis. Interestingly, mRNA transcripts and protein were detectable in a number of tissues including kidney and stomach, and, not surprisingly, the highest expression was noted in liver. Cloning of the full coding region of oatp1b2 revealed the presence of two novel splice variants. Interestingly, these splice variants were significantly expressed in organs such as the kidney, but much less in liver. Heterologous expression of the full-length Oatp1b2 cDNA revealed that taurocholic acid, estrone 3-sulfate, estradiol 17beta-glucuronide and pravastatin are substrates of this transporter. The newly identified splice variants were unable to significantly transport substrate compounds due to defects in cell surface trafficking. Our findings of murine Oatp1b2 expression and function will likely aid in better defining species related differences in OATP transporter function and the use of mouse models to predict hepatic drug disposition in humans.
Meyer Zu Schwabedissen
Henriette E
HE
Division of Clinical Pharmacology, Department of Medicine, University of Western Ontario, London, Ontario, Canada.
Ware
Joseph A
JA
Tirona
Rommel G
RG
Kim
Richard B
RB
D017398:Alternative Splicing; D000818:Animals; D015153:Blotting, Western; D004970:Estrone / Q000031:analogs & derivatives / Q000378:metabolism; D020719:Glucuronides / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D007668:Kidney / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D027381:Liver-Specific Organic Anion Transporter 1; D051379:Mice; D008856:Microscopy, Fluorescence; D008957:Models, Genetic; D027361:Organic Anion Transporters; D029362:Organic Anion Transporters, Sodium-Independent / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D016133:Polymerase Chain Reaction; D017035:Pravastatin / Q000378:metabolism; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D000074542:Solute Carrier Organic Anion Transporter Family Member 1B3; D013656:Taurocholic Acid / Q000378:metabolism
D020719:Glucuronides; D027381:Liver-Specific Organic Anion Transporter 1; D027361:Organic Anion Transporters; D029362:Organic Anion Transporters, Sodium-Independent; D020033:Protein Isoforms; C503999:SLCO1B1 protein, human; C421209:SLCO1B3 protein, human; C498887:Slco1b2 protein, mouse; D000074542:Solute Carrier Organic Anion Transporter Family Member 1B3; D004970:Estrone; D013656:Taurocholic Acid; D017035:Pravastatin; C017296:estrone sulfate