Organic Anion‐Transporting Polypeptides

Tirona, Rommel G.; Kim, Richard B.

doi:10.1002/9781118705308.ch4

Cited by 5 publications

(4 citation statements)

References 174 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A list of 40 compounds was prepared, summarizing known substrates, ,,,,− known inhibitors, ,,,− and substances without impact on OATP2B1. ,, In addition, 11 molecules were added to the library where interaction with OATP2B1 was unknown. All compounds were tested for inhibition of OATP2B1-mediated uptake of E 1 S in MDCKII-OATP2B1 cells.…”

Section: Resultsmentioning

confidence: 99%

Establishment and Validation of Competitive Counterflow as a Method To Detect Substrates of the Organic Anion Transporting Polypeptide 2B1

2018

View full text Add to dashboard Cite

The organic anion transporting polypeptide (OATP) 2B1 is ubiquitously expressed and known to facilitate cellular entry. It is widely accepted that transport proteins play a pivotal role in pharmacokinetics. Consequently, testing for interaction with drug transporters became an important part in the assessment of new molecular entities in order to predict and prevent drug-drug interactions. Recently, competitive counterflow (CCF), an indirect method allowing the identification of substrates, was successfully applied to the organic cation transporter 2. It was the aim of this study to test whether CCF can be used to identify substrates of OATP2B1. A protocol for CCF experiments using estrone 3-sulfate (E 1 S) as the driven compound in expression-verified MDCKII-OATP2B1 cells was established. The protocol was tested using a substance library, which was prior screened for inhibition of OATP2B1-mediated transport accounting for both E 1 S-binding sites. In CCF experiments, all previously reported OATP2B1 substrates significantly reduced the amount of E 1 S in equilibrium, classifying them as substrates. In addition, we identified and verified novel substrates of OATP2B1, namely, astemizole and domperidone. Results of the CCF were complemented with cytotoxicity assays or cell-based reporter gene assays to validate the finding of etoposide and teniposide or hyperforin being substrates of OATP2B1, respectively. Our study indicates that the method of CCF can be used to identify substrates of OATP2B1, irrespective, whether interacting with binding site A or A and B, but is limited by solubility issues or the amount of transporter that is expressed in the used cellular system.

show abstract

Section: Resultsmentioning

confidence: 99%

Establishment and Validation of Competitive Counterflow as a Method To Detect Substrates of the Organic Anion Transporting Polypeptide 2B1

2018

View full text Add to dashboard Cite

show abstract

“…The molecular basis for the substrate specificity and transport activity of the OATP superfamily is not well understood, despite that OATP transporters are increasingly recognized as important determinants of interindividual variation in response to many drugs in clinical use 7 . Transport by the OATPs appears to be mediated by a Na + -independent and electroneutral process, but the precise details of the transport mechanism, including the identity of the counterion, remain to be elucidated.…”

Section: Discussionmentioning

confidence: 99%

“…The clinical relevance of OATP1B1 to hepatic elimination is also evidenced by the profound effect of single nucleotide polymorphisms (SNPs) on the observed pharmacokinetic profile of drug substrates 7 . Remarkably, a previously identified SNP in SLCO1B1 has been shown to be the single most important predictor of statin-induced muscle myopathy, a relatively rare but potentially fatal side effect of statin therapy 11–12 .…”

Section: Introductionmentioning

confidence: 99%

Interaction of Three Regiospecific Amino Acid Residues Is Required for OATP1B1 Gain of OATP1B3 Substrate Specificity

DeGorter

Leake

et al. 2012

Mol. Pharmaceutics

Self Cite

View full text Add to dashboard Cite

The human organic anion-transporting polypeptides OATP1B1 (SLCO1B1) and OATP1B3 (SLCO1B3) are liver-enriched membrane transporters of major importance to hepatic uptake of numerous endogenous compounds including bile acids, steroid conjugates, hormones, and drugs including the 3-hydroxy-3-methylglutaryl Co-A reductase inhibitor (statin) family of cholesterol-lowering compounds. Despite their remarkable substrate overlap, there are notable exceptions: in particular, the gastrointestinal peptide hormone cholecystokinin-8 (CCK-8) is a high affinity substrate for OATP1B3 but not OATP1B1. We utilized homologous recombination of linear DNA by E. coli to generate a library of cDNA containing monomer size chimeric OATP1B1-1B3 and OATP1B3-1B1 transporters with randomly distributed chimeric junctions to identify three discrete regions of the transporter involved in conferring CCK-8 transport activity. Site-directed mutagenesis of three key residues in OATP1B1 transmembrane helices 1 and 10, and extracellular loop 6, to the corresponding residues in OATP1B3, resulted in a gain of CCK-8 transport by OATP1B1. The residues appear specific to CCK-8, as the mutations did not affect transport of the shared OATP1B substrate atorvastatin or the OATP1B1-specific substrate estrone sulfate. Regions involved in gain of CCK-8 transport by OATP1B1, when mapped to the crystal structures of bacterial transporters from the major facilitator superfamily, suggest these regions could readily interact with drug substrates. Accordingly, our data provide new insight into the molecular determinants of the substrate specificity of these hepatic uptake transporters with relevance to targeted drug design and prediction of drug-drug interactions.

show abstract

“…The organic anion-transporting polypeptides (OATPs) are transmembrane proteins that are members of the solute carrier (SLC) superfamily of transporters. − They include OATP1B1 and OATP1B3, which are enriched in the liver, and are responsible for the sodium-independent transport of a variety of amphipathic molecules from the blood into hepatocytes. − Transported substrates include endogenous molecules such as bile acids, hormones, and steroid conjugates, as well as xenobiotics including drugs such as methotrexate, rifampicin, and the statin family of cholesterol-lowering compounds. − OATPs play a central role in the clearance of drugs via their uptake from the hepatic portal vein. ,, Genetic polymorphisms can result in changes in the function and expression of OATPs, which may consequently lead to altered pharmacological effects, such as decreased drug efficacy, and increased risk of adverse effects. , As such, hepatic transporters are now recognized as significant contributors to the disposition, effectiveness, and adverse reactions of drugs. − Importantly, due to their roles in the ADME profiles of drugs, transporters are responsible for mediating certain drug–drug interactions (DDIs), which occur when the transport of one drug is affected by another. − For example, the coadministration of statins with cyclosporine, a potent inhibitor of OATP1B1, can result in increased blood level concentrations of the statins, which in turn may lead to dangerous myotoxic side effects . Early in vitro testing of transporter activity not only sheds insight on DDIs, but can also significantly reduce the failure rates of drugs at the clinical stage. , As a result, it is important that any involvement of transporters be determined during preclinical drug evaluation. , Accordingly, the FDA published a Draft Guidance for Industry in 2012 recommending that all drugs under investigation that are hepatically cleared be tested as substrates for OATP1B1 and OATP1B3.…”

Section: Introductionmentioning

confidence: 99%

Novel No-Wash Luminogenic Probes for the Detection of Transporter Uptake Activity

Mustafa

Zhou

et al. 2016

Bioconjugate Chem.

View full text Add to dashboard Cite

Luminogenic probes were designed and synthesized for the detection of uptake transporter activity in a lytic cell-based assay. These probes rely on a self-cleavable trimethyl lock quinone-cyanobenzothiazole (TMQ-CNBT) or trimethyl lock quinone-luciferin (TMQ-Luc) linked to the anion transporter substrate fluorescein. Upon cellular transport, the TMQ is reduced by viable cells, resulting in the facile intramolecular lactonization and rapid release of the bioluminescent reporter molecule. The uptake transporter activity can then be detected without removing and washing off the extracellular substrates. Six probes were tested with OATP1B1*1a and OATP1B3 overexpressing HEK293 cells, and all compounds showed up to 10.2-fold enhancement in uptake when compared to control cells. Uptake of TMQ-luciferin compounds 2, 4, and 6 increased linearly over time up to 30 min at a concentration ranging from 40 nM to 20 μM. The apparent Km values obtained at different time intervals up to 30 min were nearly identical for a given compound, which validates the 30 min window as appropriate for uptake transporter assays. The average apparent Km values ranged from 0.3 to 0.8 μM and 0.2 to 1.3 μM for OATP1B1*1a and OATP1B3, respectively, indicating good affinities to these anion transporters. Furthermore, uptake of compound 2 was inhibited by two inhibitors of OATP1B1*1a and OATP1B3: rifampicin and ritonavir. The preliminary results obtained from compound 2 exhibited a time-dependent, saturatable, and inhibitable nature of uptake, indicating the feasibility of using the probe for the detection of a transporter-mediated process. This add-and-read homogeneous assay may provide a convenient, rapid, and facile way to detect changes in transporter activity in a high-throughput format, and this assay design strategy could create a new platform for a general cell uptake assay for biomaterials in the future.

show abstract

Organic Anion‐Transporting Polypeptides

Cited by 5 publications

References 174 publications

Establishment and Validation of Competitive Counterflow as a Method To Detect Substrates of the Organic Anion Transporting Polypeptide 2B1

Establishment and Validation of Competitive Counterflow as a Method To Detect Substrates of the Organic Anion Transporting Polypeptide 2B1

Interaction of Three Regiospecific Amino Acid Residues Is Required for OATP1B1 Gain of OATP1B3 Substrate Specificity

Novel No-Wash Luminogenic Probes for the Detection of Transporter Uptake Activity

Contact Info

Product

Resources

About