TY - JOUR T1 - Evaluation of Organic Anion Transporter 1A2-knockin Mice as a Model of Human Blood-Brain Barrier JF - Drug Metabolism and Disposition JO - Drug Metab Dispos DO - 10.1124/dmd.118.081877 SP - dmd.118.081877 AU - Yamato Sano AU - Tadahaya Mizuno AU - Tatsuki Mochizuki AU - Yasuno Uchida AU - Mina Umetsu AU - Tetsuya Terasaki AU - Hiroyuki Kusuhara Y1 - 2018/01/01 UR - http://dmd.aspetjournals.org/content/early/2018/08/28/dmd.118.081877.abstract N2 - The present study aimed to establish a humanized mouse model with which to explore OATP1A2-mediated transcellular transport of drug substrates across the blood - brain barrier (BBB), and to evaluate the usefulness of the humanized mice in preclinical studies. Sulpiride, amisulpride, sultopride, and triptans were used as probes to discriminate OATP1A2 and Oatp1a4. We generated a mouse line humanized for OATP1A2 by introducing the coding region downstream of the Oatp1a4 promoter using the CRISPR/Cas9 technique. In the mice generated, OATP1A2 mRNA in the brain was increased corresponding to disappearance of Oatp1a4. OATP1A2 was enriched in the BBB fraction where OATP1A2 was localized on both the luminal and abluminal sides of the BBB. Unfortunately, study in vivo employing sulpiride and zolmitriptan as probes did not indicate any difference in their brain-to-plasma ratio between the control and humanized mice. Quantitative targeted absolute proteomic analysis of the BBB fraction from the humanized mice revealed that almost all analyzed transporters and membrane proteins except for P-glycoprotein were expressed at similar levels to those in control mice. The quantitative levels of OATP1A2 differed depending on the peptide quantified, which suggests that incomplete translation or posttranslational modification may occur. The blood-to-brain transport of zolmitriptan, determined by brain perfusion in situ, was 1.6-fold higher in the humanized mice than in the controls, whereas that of sulpiride was not significantly changed. To our knowledge, we established a mouse line humanized for a BBB uptake transporter for the first time, and succeeded in detecting OATP1A2-mediated uptake across the BBB. ER -