Solute Carrier Family of the Organic Anion-Transporting Polypeptides 1A2– Madin-Darby Canine Kidney II: A Promising In Vitro System to Understand the Role of Organic Anion-Transporting Polypeptide 1A2 in Blood-Brain Barrier Drug Penetration

Abstract

Organic anion-transporting polypeptide (OATP) 1A2 has the potential to be a target for central nervous system drug delivery due to its luminal localization at the human blood-brain barrier and broad substrate specificity. We found OATP1A2 mRNA expression in the human brain to be comparable to breast cancer resistance protein and OATP2B1 and much higher than P-glycoprotein (P-gp), and confirmed greater expression in the brain relative to other tissues. The goal of this study was to establish a model system to explore OATP1A2-mediated transcellular transport of substrate drugs and the interplay with P-gp. In vitro (human embryonic kidney 293 cells stably expressing Oatp1a4, the closest murine isoform) and in vivo (naïve and Oatp1a4 knock-out mice) studies with OATP1A2 substrate triptan drugs demonstrated that these drugs were not Oatp1a4 substrates. This species difference demonstrates that the rodent is not a good model to investigate the active brain uptake of potential OATP1A2 substrates. Thus, we constructed a novel OATP1A2 expressing Madin-Darby canine kidney (MDCK) II wild type and an MDCKII-multidrug resistance protein 1 (MDR1) system using BacMam virus transduction. The spatial expression pattern of OATP1A2 after transduction in MDCKII-MDR1 cells was superimposed to P-gp, confirming apical membrane localization. OATP1A2-mediated uptake of zolmitriptan, rosuvastatin, and fexofenadine across monolayers increased with increasing OATP1A2 protein expression. OATP1A2 counteracted P-gp efflux for cosubstrates zolmitriptan and fexofenadine. A three-compartment model incorporating OATP1A2-mediated influx was used to quantitatively describe the time-and concentration-dependent apical-to-basolateral transcellular transport of rosuvastatin across OATP1A2 expressing the MDCKII monolayer. This novel, simple and versatile experimental system is useful for understanding the contribution of OATP1A2-mediated transcellular transport across barriers, such as the bloodbrain barrier.

The 5′-AMP-Activated Protein Kinase Regulates the Function and Expression of Human Organic Anion Transporting Polypeptide 1A2

“…OATP1A2 is abundantly located in the epithelium of many tissues and influences the disposition of numerous drugs, xenobiotics, and endobiotics (Kullak-Ublick et al, 1995;Steckelbroeck et al, 2004;Liu and Li, 2014). At the apical membrane of renal tubular cells, OATP1A2 mediates the reabsorption of xenobiotics (Lee et al, 2005); in the biliary epithelium, OATP1A2 facilitates the excretion of xenobiotics into bile; and at the luminal membrane of the blood-brain barrier, OATP1A2 modulates the uptake of opioid analgesic peptides and other central nervous system-active agents into the brain (Liu et al, 2015). More recently, OATP1A2 has been detected on the apical membrane of the retinal pigment epithelium, where it facilitates the uptake of retinoids (Chan et al, 2015b;Gao et al, 2015).…”

In vitro acute and developmental neurotoxicity screening: an overview of cellular platforms and high-throughput technical possibilities

“…Since differences between human and rodent isoforms of the transport proteins expressed by ECs mean that certain compounds can be substrates for the human isoform, but not for the rodent counterpart, it is important to use cells of human origin for BBB models to get results that translate to human safety (Liu et al 2015).…”

“…Also, due to the presence of some nonconserved histidine residues in the human sequence, TLR4 triggers for instance contact hypersensitivity to nickel in humans, but not in mice (Schmidt et al 2010). Differences in the primary sequences between orthologs can also lead to differences in the selectivity of the transport proteins of the blood-brain barrier leading to differences in the uptake of certain compounds (Liu et al 2015).…”

Correlation between Membrane Protein Expression Levels and Transcellular Transport Activity for Breast Cancer Resistance Protein

“…MDCKII-WT cells express canine P-gp but not BCRP. In addition, endogenous P-gp expression can be impacted by BacMam virus load (Liu et al, 2015). In previous studies, the BCRP-expressing in vitro transwell system was not found to be predictive of in vivo transport activity (Enokizono et al, 2008;Zhao et al, 2009), likely because P-gp/BCRP cosubstrates were included and the activity of endogenous P-gp was ignored.…”