648 results on '"Organic Cation Transporter 1"'
Search Results
2. Genetic Variation in Organic Cation Transport 1 (OCT1) and Its Significance for Morphine Pharmacokinetics
- Author
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Danish Council for Independent Research, The Faculty of Health Sciences SDU, Region of Southern Denmark, and Ida Kuhlmann, MD, phd student
- Published
- 2020
3. Inter- and Intra-individual Variations in Metformin Pharmacokinetics - The Importance of Genes and Drug Interactions
- Author
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Ida Kuhlmann, Principal investigator
- Published
- 2020
4. Expression status of p53 and organic cation transporter 1 is correlated with poor response to preoperative chemotherapy in esophageal squamous cell carcinoma
- Author
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Masahiro Izutsu, Takanori Domoto, Shingo Kamoshida, Hiroyuki Ohsaki, Hiroshi Matsuoka, Yusuke Umeki, Kazuya Shiogama, Masaya Hirayama, Koichi Suda, and Ichiro Uyama
- Subjects
Cisplatin ,Esophageal squamous cell carcinoma ,Preoperative chemotherapy ,Organic cation transporter 1 ,p53 ,Surgery ,RD1-811 ,Neoplasms. Tumors. Oncology. Including cancer and carcinogens ,RC254-282 - Abstract
Abstract Background Esophageal squamous cell carcinoma (ESCC) is a highly malignant neoplasm. DNA-damaging drugs, such as cisplatin (CDDP) and 5-fluorouracil (5-FU), are most frequently used in preoperative chemotherapy for ESCC. However, the response to preoperative chemotherapy varies among patients. p53, encoded by TP53, participates in apoptotic pathways following chemotherapy with DNA-damaging drugs, and mutation of TP53 contributes to chemoresistance. Organic cation transporter 1 (OCT1) participates in the uptake of CDDP, and its reduced expression is associated with CDDP resistance. The aim of this study was to evaluate the predictive impact of the expression status of p53 and OCT1 in response to preoperative chemotherapy in ESCC. Methods We retrospectively assessed 66 ESCC patients who received preoperative chemotherapy with CDDP/5-FU (CF) or docetaxel/CDDP/5-FU (DCF). p53 and OCT1 expression in pretreatment biopsy specimens was immunohistochemically determined and correlated with histological response to preoperative chemotherapy. Results p53 with wild-type (p53WT-ex) and mutant-type (p53MT-ex) expression patterns was identified in 40.9% and 59.1% of patients, respectively. High expression of OCT1 (OCT1High) was detected in 45.5%, and the remaining 54.5% showed low expression (OCT1Low). In a univariate analysis of the entire cohort, p53MT-ex was significantly correlated with poor response (P = 0.026), whereas OCT1Low showed marginal significance (P = 0.091). In a combined analysis, tumors with either p53MT-ex or OCT1Low showed a significant correlation with poor response compared with tumors with both p53WT-ex and OCT1High (P < 0.001). The sensitivity, specificity, and accuracy of combined p53/OCT1 were 93.9%, 47.1%, and 81.8%, respectively. Multivariate analysis identified p53 (P = 0.017), OCT1 (P = 0.032), and combined p53/OCT1 (P < 0.001) as independent predictors of histological response. When samples were stratified according to chemotherapy regimen in the univariate analysis, combined p53/OCT1 was the only significant factor for poor response in the CF (P = 0.011) and DCF (P = 0.021) groups, whereas p53 showed no statistical significance. Conclusions Our results suggest that either p53MT-ex or OCT1Low expression in pretreatment biopsy specimens may be a potential predictor of poor response to preoperative chemotherapy with the CF-based regimens in ESCC, although the specificity needs to be improved.
- Published
- 2022
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5. IMPACT OF 420DEL (RS72552763) ORGANIC CATION TRANSPORTER 1 POLYMORPHISM ON THERAPEUTIC RESPONSE TO METFORMIN IN TYPE2 DIABETIC PATIENTS IN THE IRAQI POPULATION.
- Author
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Jabaar, Halah Kareem, Khalaf, Ban Hoshi, Abu-Almaaly, Hassan, and Mahdi, Jabbar Fadeel
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METFORMIN ,ORGANIC cation transporters ,PEOPLE with diabetes ,OUTPATIENT medical care ,TYPE 2 diabetes ,GENETIC polymorphisms - Abstract
Metformin is one of the most widely prescribed medications for the treatment of type 2 diabetes (T2DM) but metformin response varies greatly between individuals, polymorphisms in genes that regulate metformin's pharmacokinetics and pharmacodynamics may be to blame for these phenotypic differences in drug disposition and action. In this study, we investigated the association between 420del (rs72552763) organic cation transporter 1 (OCT1) polymorphism and therapeutic response to metformin in type 2 diabetic patients, A total of 200 diabetic patients enrolled in this cross-sectional study, patients were chosen when they visit outpatient clinic for medical care. Fasting serum glucose, fasting serum insulin and HbA1c, which indicate metformin response were measured. The result of the study indicate there was a significant association between the presence of 420del (rs72552763) in diabetic patients and the variability response to metformin, the multinomial logistic regress analysis indicates that most patients with the reference allele (wild type) and heterozygous alleles of OCT1 (420del) had statistically significant metabolic responses to metformin, whereas patients with mutant alleles had less or no response. In conclusion, Genetic polymorphism of OCT1transporter 420del (rs72552763) contributed to the variability of therapeutic response to metformin treatment. [ABSTRACT FROM AUTHOR]
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- 2022
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6. Comprehensive characterization of the OCT1 phenylalanine-244-alanine substitution reveals highly substrate-dependent effects on transporter function.
- Author
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Wittern CI, Schröder S, Jensen O, Brockmöller J, and Gebauer L
- Abstract
Organic cation transporters (OCTs) can transport structurally highly diverse substrates. The molecular basis of this extensive polyspecificity has been further elucidated by cryogenic electron microscopy. Apparently, in addition to negatively charged amino acids, aromatic residues may contribute to substrate binding and substrate selectivity. In this study, we provide a comprehensive characterization of phenylalanine 244 in OCT1 function. We analyzed the uptake of 144 OCT1 substrates for the phenylalanine 244 to alanine substitution compared to wild-type OCT1. This substitution had highly substrate-specific effects ranging from transport reduced to 10% of wild-type activity up to 8-fold increased transport rates. Four percent of substrates showed strongly increased uptake (> 200% of wild type) whereas 39% showed strongly reduced transport (< 50% of wild type). Particularly with larger, more hydrophobic, and more aromatic substrates, the Phe244Ala substitution resulted in higher transport rates and lower inhibition of the transporter. In contrast, substrates with a lower molecular weight and less aromatic rings showed generally decreased uptake rates. A comparison of our data to available transport kinetic data demonstrates that generally, high-affinity low-capacity substrates show increased uptake by the Phe244Ala substitution whereas low-affinity high-capacity substrates are characterized by reduced transport rates. Altogether, our study provides the first comprehensive characterization of the functional role of an aromatic amino acid within the substrate translocation pathway of OCT1. The pleiotropic function further highlights that Phenylalanine 244 interacts in a highly specific manner with OCT1 substrates and inhibitors., Competing Interests: Conflicts of interest The authors declare that they have no conflicts of interest with the contents of this article., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)
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- 2024
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7. Inhibitory effects of flavonoids on organic cation transporter 1: Implications for food/herb-drug interactions and hepatoprotective effects.
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Bai W, Tan H, Duan X, Hu J, Wang F, Wu J, Bai J, and Hu J
- Abstract
Organic cation transporter 1 (OCT1, gene symbol: SLC22A1) is mainly responsible for the hepatic uptake of various cationic drugs, closely associated with drug-induced liver injury (DILI). Screening and identifying potent OCT1 inhibitors with little toxicity in natural products is of great value in alleviating OCT1-mediated liver injury. Flavonoids, a group of polyphenols commonly found in foodstuffs and herbal products, have been reported to cause transporter-mediated food/herb-drug interactions (FDIs). Our objective was to investigate potential inhibitors of OCT1 from 96 flavonoids, evaluate the hepatoprotective effects on retrorsine-induced liver injury, and clarify the structure-activity relationships of flavonoids with OCT1. Thirteen flavonoids exhibited significant inhibition (>50%) on OCT1 in OCT1-HEK293 cells. Among them, the five strongest flavonoid inhibitors (IC
50 < 10 μM), including α-naphthoflavone, apigenin, 6-hydroxyflavone, luteolin, and isosilybin markedly decreased oxaliplatin-induced cytotoxicity. In retrorsine-induced liver injury models, they also reduced alanine aminotransferase (ALT) and aspartate aminotransferase (AST) to different levels, the best of which was 6-hydroxyflavone. The pharmacophore model clarified that hydrogen bond acceptors at the 4,8,5' position might play a vital role in the inhibitory effect of flavonoids on OCT1. Taken together, our findings would pave the way to predicting the potential risks of flavonoid-related FDIs in humans and optimizing flavonoid structure to alleviate OCT1-mediated liver injury., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)- Published
- 2024
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8. Studies from Kanazawa University Yield New Information about Organic Cation Transport Proteins (Functional Expression of Carnitine/organic Cation Transporter 1 In Murine Choroid Plexus).
- Abstract
A study conducted at Kanazawa University in Ishikawa, Japan, investigated the role of organic cation transporter 1 (OCTN1) in the elimination of substances from cerebrospinal fluid (CSF). The researchers used tritium-labeled ergothioneine as a substrate and found that OCTN1 is functionally expressed in the choroid plexus (CP) and is involved in the elimination of ergothioneine from CSF in mice. This research provides new insights into the transport of substances between blood and CSF in the central nervous system. The study was supported by the Ministry of Education, Culture, Sports, Science and Technology, Japan. [Extracted from the article]
- Published
- 2024
9. Discovery of Competitive and Noncompetitive Ligands of the Organic Cation Transporter 1 (OCT1; SLC22A1)
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Chen, Eugene C, Khuri, Natalia, Liang, Xiaomin, Stecula, Adrian, Chien, Huan-Chieh, Yee, Sook Wah, Huang, Yong, Sali, Andrej, and Giacomini, Kathleen M
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Liver Disease ,Digestive Diseases ,Drug Discovery ,HEK293 Cells ,Humans ,Ligands ,Molecular Docking Simulation ,Organic Cation Transporter 1 ,Small Molecule Libraries ,Medicinal and Biomolecular Chemistry ,Organic Chemistry ,Pharmacology and Pharmaceutical Sciences ,Medicinal & Biomolecular Chemistry - Abstract
Organic cation transporter 1 (OCT1) plays a critical role in the hepatocellular uptake of structurally diverse endogenous compounds and xenobiotics. Here we identified competitive and noncompetitive OCT1-interacting ligands in a library of 1780 prescription drugs by combining in silico and in vitro methods. Ligands were predicted by docking against a comparative model based on a eukaryotic homologue. In parallel, high-throughput screening (HTS) was conducted using the fluorescent probe substrate ASP+ in cells overexpressing human OCT1. Thirty competitive OCT1 ligands, defined as ligands predicted in silico as well as found by HTS, were identified. Of the 167 ligands identified by HTS, five were predicted to potentially cause clinical drug interactions. Finally, virtual screening of 29 332 metabolites predicted 146 competitive OCT1 ligands, of which an endogenous neurotoxin, 1-benzyl-1,2,3,4-tetrahydroisoquinoline, was experimentally validated. In conclusion, by combining docking and in vitro HTS, competitive and noncompetitive ligands of OCT1 can be predicted.
- Published
- 2017
10. Expression status of p53 and organic cation transporter 1 is correlated with poor response to preoperative chemotherapy in esophageal squamous cell carcinoma.
- Author
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Izutsu, Masahiro, Domoto, Takanori, Kamoshida, Shingo, Ohsaki, Hiroyuki, Matsuoka, Hiroshi, Umeki, Yusuke, Shiogama, Kazuya, Hirayama, Masaya, Suda, Koichi, and Uyama, Ichiro
- Subjects
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ORGANIC cation transporters , *NEOADJUVANT chemotherapy , *SQUAMOUS cell carcinoma , *ESOPHAGEAL cancer , *UNIVARIATE analysis - Abstract
Background: Esophageal squamous cell carcinoma (ESCC) is a highly malignant neoplasm. DNA-damaging drugs, such as cisplatin (CDDP) and 5-fluorouracil (5-FU), are most frequently used in preoperative chemotherapy for ESCC. However, the response to preoperative chemotherapy varies among patients. p53, encoded by TP53, participates in apoptotic pathways following chemotherapy with DNA-damaging drugs, and mutation of TP53 contributes to chemoresistance. Organic cation transporter 1 (OCT1) participates in the uptake of CDDP, and its reduced expression is associated with CDDP resistance. The aim of this study was to evaluate the predictive impact of the expression status of p53 and OCT1 in response to preoperative chemotherapy in ESCC. Methods: We retrospectively assessed 66 ESCC patients who received preoperative chemotherapy with CDDP/5-FU (CF) or docetaxel/CDDP/5-FU (DCF). p53 and OCT1 expression in pretreatment biopsy specimens was immunohistochemically determined and correlated with histological response to preoperative chemotherapy. Results: p53 with wild-type (p53WT-ex) and mutant-type (p53MT-ex) expression patterns was identified in 40.9% and 59.1% of patients, respectively. High expression of OCT1 (OCT1High) was detected in 45.5%, and the remaining 54.5% showed low expression (OCT1Low). In a univariate analysis of the entire cohort, p53MT-ex was significantly correlated with poor response (P = 0.026), whereas OCT1Low showed marginal significance (P = 0.091). In a combined analysis, tumors with either p53MT-ex or OCT1Low showed a significant correlation with poor response compared with tumors with both p53WT-ex and OCT1High (P < 0.001). The sensitivity, specificity, and accuracy of combined p53/OCT1 were 93.9%, 47.1%, and 81.8%, respectively. Multivariate analysis identified p53 (P = 0.017), OCT1 (P = 0.032), and combined p53/OCT1 (P < 0.001) as independent predictors of histological response. When samples were stratified according to chemotherapy regimen in the univariate analysis, combined p53/OCT1 was the only significant factor for poor response in the CF (P = 0.011) and DCF (P = 0.021) groups, whereas p53 showed no statistical significance. Conclusions: Our results suggest that either p53MT-ex or OCT1Low expression in pretreatment biopsy specimens may be a potential predictor of poor response to preoperative chemotherapy with the CF-based regimens in ESCC, although the specificity needs to be improved. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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11. Molecular Properties of Drugs Interacting with SLC22 Transporters OAT1, OAT3, OCT1, and OCT2: A Machine-Learning Approach
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Liu, Henry C, Goldenberg, Anne, Chen, Yuchen, Lun, Christina, Wu, Wei, Bush, Kevin T, Balac, Natasha, Rodriguez, Paul, Abagyan, Ruben, and Nigam, Sanjay K
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Pharmacology and Pharmaceutical Sciences ,Biomedical and Clinical Sciences ,Kidney Disease ,Computational Biology ,Hydrogen-Ion Concentration ,Machine Learning ,Membrane Transport Proteins ,Models ,Molecular ,Organic Anion Transport Protein 1 ,Organic Anion Transporters ,Sodium-Independent ,Organic Cation Transporter 1 ,Pharmaceutical Preparations ,Protein Binding ,Protein Conformation ,Substrate Specificity ,Pharmacology & Pharmacy ,Pharmacology and pharmaceutical sciences - Abstract
Statistical analysis was performed on physicochemical descriptors of ∼250 drugs known to interact with one or more SLC22 "drug" transporters (i.e., SLC22A6 or OAT1, SLC22A8 or OAT3, SLC22A1 or OCT1, and SLC22A2 or OCT2), followed by application of machine-learning methods and wet laboratory testing of novel predictions. In addition to molecular charge, organic anion transporters (OATs) were found to prefer interacting with planar structures, whereas organic cation transporters (OCTs) interact with more three-dimensional structures (i.e., greater SP3 character). Moreover, compared with OAT1 ligands, OAT3 ligands possess more acyclic tetravalent bonds and have a more zwitterionic/cationic character. In contrast, OCT1 and OCT2 ligands were not clearly distinquishable form one another by the methods employed. Multiple pharmacophore models were generated on the basis of the drugs and, consistent with the machine-learning analyses, one unique pharmacophore created from ligands of OAT3 possessed cationic properties similar to OCT ligands; this was confirmed by quantitative atomic property field analysis. Virtual screening with this pharmacophore, followed by transport assays, identified several cationic drugs that selectively interact with OAT3 but not OAT1. Although the present analysis may be somewhat limited by the need to rely largely on inhibition data for modeling, wet laboratory/in vitro transport studies, as well as analysis of drug/metabolite handling in Oat and Oct knockout animals, support the general validity of the approach-which can also be applied to other SLC and ATP binding cassette drug transporters. This may make it possible to predict the molecular properties of a drug or metabolite necessary for interaction with the transporter(s), thereby enabling better prediction of drug-drug interactions and drug-metabolite interactions. Furthermore, understanding the overlapping specificities of OATs and OCTs in the context of dynamic transporter tissue expression patterns should help predict net flux in a particular tissue of anionic, cationic, and zwitterionic molecules in normal and pathophysiological states.
- Published
- 2016
12. A phosphotyrosine switch regulates organic cation transporters.
- Author
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Sprowl, Jason A, Ong, Su Sien, Gibson, Alice A, Hu, Shuiying, Du, Guoqing, Lin, Wenwei, Li, Lie, Bharill, Shashank, Ness, Rachel A, Stecula, Adrian, Offer, Steven M, Diasio, Robert B, Nies, Anne T, Schwab, Matthias, Cavaletti, Guido, Schlatter, Eberhard, Ciarimboli, Giuliano, Schellens, Jan HM, Isacoff, Ehud Y, Sali, Andrej, Chen, Taosheng, Baker, Sharyn D, Sparreboom, Alex, and Pabla, Navjotsingh
- Subjects
Ganglia ,Spinal ,Hela Cells ,Animals ,Humans ,Mice ,Organoplatinum Compounds ,Phosphotyrosine ,Organic Anion Transporters ,Organic Cation Transport Proteins ,Organic Cation Transporter 1 ,Antineoplastic Agents ,Protein Kinase Inhibitors ,Models ,Molecular ,Proto-Oncogene Proteins c-yes ,Protein-Tyrosine Kinases ,HEK293 Cells ,Organic Cation Transporter 2 ,Oxaliplatin ,Liver-Specific Organic Anion Transporter 1 ,HeLa Cells - Abstract
Membrane transporters are key determinants of therapeutic outcomes. They regulate systemic and cellular drug levels influencing efficacy as well as toxicities. Here we report a unique phosphorylation-dependent interaction between drug transporters and tyrosine kinase inhibitors (TKIs), which has uncovered widespread phosphotyrosine-mediated regulation of drug transporters. We initially found that organic cation transporters (OCTs), uptake carriers of metformin and oxaliplatin, were inhibited by several clinically used TKIs. Mechanistic studies showed that these TKIs inhibit the Src family kinase Yes1, which was found to be essential for OCT2 tyrosine phosphorylation and function. Yes1 inhibition in vivo diminished OCT2 activity, significantly mitigating oxaliplatin-induced acute sensory neuropathy. Along with OCT2, other SLC-family drug transporters are potentially part of an extensive 'transporter-phosphoproteome' with unique susceptibility to TKIs. On the basis of these findings we propose that TKIs, an important and rapidly expanding class of therapeutics, can functionally modulate pharmacologically important proteins by inhibiting protein kinases essential for their post-translational regulation.
- Published
- 2016
13. Rapid Method To Determine Intracellular Drug Concentrations in Cellular Uptake Assays: Application to Metformin in Organic Cation Transporter 1–Transfected Human Embryonic Kidney 293 Cells
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Chien, Huan-Chieh, Zur, Arik A, Maurer, Tristan S, Yee, Sook Wah, Tolsma, John, Jasper, Paul, Scott, Dennis O, and Giacomini, Kathleen M
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Medical Physiology ,Biomedical and Clinical Sciences ,Biological Transport ,Cell Line ,Endoplasmic Reticulum ,HEK293 Cells ,Humans ,Metformin ,Mitochondria ,Organic Cation Transporter 1 ,Transfection ,Pharmacology and Pharmaceutical Sciences ,Pharmacology & Pharmacy ,Pharmacology and pharmaceutical sciences - Abstract
Because of the importance of intracellular unbound drug concentrations in the prediction of in vivo concentrations that are determinants of drug efficacy and toxicity, a number of assays have been developed to assess in vitro unbound concentrations of drugs. Here we present a rapid method to determine the intracellular unbound drug concentrations in cultured cells, and we apply the method along with a mechanistic model to predict concentrations of metformin in subcellular compartments of stably transfected human embryonic kidney 293 (HEK293) cells. Intracellular space (ICS) was calculated by subtracting the [(3)H]-inulin distribution volume (extracellular space, ECS) from the [(14)C]-urea distribution volume (total water space, TWS). Values obtained for intracellular space (mean ± S.E.M.; μl/10(6) cells) of monolayers of HEK cells (HEK-empty vector [EV]) and cells overexpressing human organic cation transporter 1 (HEK-OCT1), 1.21± 0.07 and 1.25±0.06, respectively, were used to determine the intracellular metformin concentrations. After incubation of the cells with 5 µM metformin, the intracellular concentrations were 26.4 ± 7.8 μM and 268 ± 11.0 μM, respectively, in HEK-EV and HEK-OCT1. In addition, intracellular metformin concentrations were lower in high K(+) buffer (140 mM KCl) compared with normal K(+) buffer (5.4 mM KCl) in HEK-OCT1 cells (54.8 ± 3.8 μM and 198.1 ± 11.2 μM, respectively; P < 0.05). Our mechanistic model suggests that, depending on the credible range of assumed physiologic values, the positively charged metformin accumulates to particularly high levels in endoplasmic reticulum and/or mitochondria. This method together with the computational model can be used to determine intracellular unbound concentrations and to predict subcellular accumulation of drugs in other complex systems such as primary cells.
- Published
- 2016
14. No significant influence of OCT1 genotypes on the pharmacokinetics of morphine in adult surgical patients.
- Author
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Kuhlmann, Ida, Hjelmar Petersen, Rasmus, Overgaard, Morten, Dornonville de la Cour, Kenn, Zwisler, Stine, Bjerregaard Stage, Tore, Hougaard Christensen, Mette Marie, Bergmann, Troels K., Damkier, Per, Gadegaard Jensen, Anders, Nielsen, Flemming, and Brøsen, Kim
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MORPHINE , *PHARMACOKINETICS , *GENETIC variation , *GENOTYPES , *ORGANIC cation transporters , *OPIOIDS - Abstract
We investigated the impact of genetic variants in OCT1 (SLC22A1) on morphine, morphine‐3‐glucuronide (M3G) and morphine‐6‐glucuronide (M6G) pharmacokinetics in adult patients scheduled for major surgery. Blood samples were taken before and 5, 10, 15, 30, 45, 60 and 90 min after a bolus of morphine (0.15 mg/kg). Patients were genotyped for the genetic variants (rs12208357, rs34059508, rs72552763 and rs34130495) in OCT1. Eighty‐six patients completed the trial. The mean difference (95% confidence interval) for dose adjusted morphine, M3G and M6G AUC was 0.9 (−0.7–2.4), −5.9 (−11.8 to −0.03) and −1.1 (−2.5–0.4) h/L*10−6, respectively, in patients with two reduced function alleles compared to patients with no reduced function alleles in OCT1. Accordingly, the (AUCM3G/Dose)/(AUCmorphine/Dose) and (AUCM6G/Dose)/(AUCmorphine/Dose) ratio was reduced, −1.8 (−3.2 to −0.4) and −0.4 (−0.7 to −0.03), respectively, when comparing the same groups. OCT1 variants had no influence on the experience of pain, adverse events or the number of PCA doses used. In conclusion, genetic variants in OCT1 had a small and clinically unimportant impact on the exposure of morphine after intravenous administration. Our results do not support pre‐emptive genotyping for OCT1 prior to morphine administration in patients scheduled for major surgery. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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15. Intronic Variants in OCT1 are Associated with All-Cause and Cardiovascular Mortality in Metformin Users with Type 2 Diabetes
- Author
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Schweighofer N, Genser B, Maerz W, Kleber ME, Trummer O, Pieber TR, and Obermayer-Pietsch B
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organic cation transporter 1 ,snp ,t2dm ,cardiovascular death ,metformin ,Specialties of internal medicine ,RC581-951 - Abstract
Natascha Schweighofer,1,2 Bernd Genser,3,4 Winfried Maerz,5,6 Marcus E Kleber,5 Olivia Trummer,1 Thomas R Pieber,1,2 Barbara Obermayer-Pietsch1,2 1Department of Internal Medicine, Division of Endocrinology and Diabetology, Medical University Graz, Graz, Austria; 2CBmed GmbH, Center for Biomarker Research in Medicine, Graz, Austria; 3BG Stats Consulting, Vienna, Austria; 4Institute of Public Health, Social and Preventive Medicine, Medical Faculty of Mannheim, University of Heidelberg, Mannheim, Germany; 5Medical Clinic V (Nephrology, Hypertensiology, Rheumatology, Endocrinology, Diabetology), Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany; 6SynLaboratory Academy, SynLaboratory Holding Deutschland GmbH, Mannheim and Augsburg, GermanyCorrespondence: Barbara Obermayer-PietschDepartment of Internal Medicine, Division of Endocrinology and Diabetology, Medical University Graz, Auenbruggerplatz 15, Graz A-8036, AustriaTel +43 316 385 80253Fax +43 316 385 13428Email barbara.obermayer@medunigraz.atPurpose: Organic cation transporters (Octs) use cations like endogenous compounds, toxins, and drugs, such as metformin, as substrates. Therefore, these proteins determine the pharmacokinetics and -dynamics of metformin and thus its efficacy. Of note, metformin is today the most commonly used pharmaceutical in the treatment of type 2 diabetes (T2DM) with nevertheless a great variability in clinical response, which attributes to genetic variances. The aim of this study was to determine the influence of intronic OCT1 SNPs on prevalence of all-cause and cardiovascular death.Patients and Methods: Genotypes of 27 intronic SNPs in OCT1 were investigated in the LURIC study, a prospective cohort of 3316 participants scheduled for coronary angiography. We investigated whether these variants were associated with all-cause and cardiovascular death in 73 individuals with T2DM under metformin therapy, in individuals without diabetes, individuals with T2DM and individuals with T2DM without metformin therapy.Results: In a multivariate Cox regression analysis adjusted for classical cardiovascular risk factors, 4 intronic OCT1 SNPs were significantly associated with all-cause and cardiovascular mortality in individuals with T2DM on metformin therapy.Conclusion: According to their OCT1 genotype, some individuals with T2DM on metformin therapy might be prone to an increased risk of cardiovascular death.Keywords: organic cation transporter 1, SNP, T2DM, cardiovascular death, metformin
- Published
- 2020
16. Prediction and validation of enzyme and transporter off-targets for metformin
- Author
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Yee, Sook Wah, Lin, Lawrence, Merski, Matthew, Keiser, Michael J, Gupta, Aakash, Zhang, Youcai, Chien, Huan-Chieh, Shoichet, Brian K, and Giacomini, Kathleen M
- Subjects
Pharmacology and Pharmaceutical Sciences ,Biomedical and Clinical Sciences ,Digestive Diseases ,5.1 Pharmaceuticals ,Development of treatments and therapeutic interventions ,Amine Oxidase (Copper-Containing) ,Biological Transport ,Cell Line ,Diabetes Mellitus ,Type 2 ,HEK293 Cells ,Humans ,Intestinal Mucosa ,Kinetics ,Membrane Transport Proteins ,Metformin ,Octamer Transcription Factor-3 ,Organic Cation Transporter 1 ,Serotonin Plasma Membrane Transport Proteins ,Organic cation transporter ,Histamine ,Serotonin ,Putrescine ,Diamine oxidase ,Pharmacology & Pharmacy ,Pharmacology and pharmaceutical sciences - Abstract
Metformin, an established first-line treatment for patients with type 2 diabetes, has been associated with gastrointestinal (GI) adverse effects that limit its use. Histamine and serotonin have potent effects on the GI tract. The effects of metformin on histamine and serotonin uptake were evaluated in cell lines overexpressing several amine transporters (OCT1, OCT3 and SERT). Metformin inhibited histamine and serotonin uptake by OCT1, OCT3 and SERT in a dose-dependent manner, with OCT1-mediated amine uptake being most potently inhibited (IC50 = 1.5 mM). A chemoinformatics-based method known as Similarity Ensemble Approach predicted diamine oxidase (DAO) as an additional intestinal target of metformin, with an E-value of 7.4 × 10(-5). Inhibition of DAO was experimentally validated using a spectrophotometric assay with putrescine as the substrate. The Ki of metformin for DAO was measured to be 8.6 ± 3.1 mM. In this study, we found that metformin inhibited intestinal amine transporters and DAO at concentrations that may be achieved in the intestine after therapeutic doses. Further studies are warranted to determine the relevance of these interactions to the adverse effects of metformin on the gastrointestinal tract.
- Published
- 2015
17. OCT1 in hepatic steatosis and thiamine disposition
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Chen, Ligong, Yee, Sook Wah, and Giacomini, Kathleen M
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Biochemistry and Cell Biology ,Biological Sciences ,Animals ,Energy Metabolism ,Fatty Liver ,Humans ,Metformin ,Mice ,Models ,Biological ,Organic Cation Transporter 1 ,Thiamine ,Developmental Biology ,Biochemistry and cell biology - Published
- 2015
18. University of Sao Paulo Researcher Publishes New Study Findings on Hepatitis C Virus (Liver Fibrosis Stages Affect Organic Cation Transporter 1/2 Activities in Hepatitis C Virus-Infected Patients).
- Abstract
A new study conducted by researchers at the University of Sao Paulo in Brazil explores the impact of liver fibrosis stages on the activity of organic cation transporters in patients with chronic hepatitis C virus (HCV) infection. The study found that the in vivo activity of these transporters was reduced by approximately 25% in participants with advanced liver fibrosis and cirrhosis after achieving sustained virologic response. The findings suggest that the activity of organic cation transporters depends on the stage of liver fibrosis in individuals with chronic HCV infection. This research provides valuable insights into the relationship between liver fibrosis and HCV infection. [Extracted from the article]
- Published
- 2024
19. Effects of a Common Eight Base Pairs Duplication at the Exon 7-Intron 7 Junction on Splicing, Expression, and Function of OCT1
- Author
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Sarah Römer, Marleen J. Meyer, Kathrin Klein, Lennart V. Schneider, Johannes Matthaei, Ana Tzvetkova, Joanna Łapczuk-Romańska, Jochen Gaedcke, Marek Droździk, Jürgen Brockmöller, Anne T. Nies, and Mladen V. Tzvetkov
- Subjects
ins/del variant ,organic cation transporter 1 ,SLC22A1 ,minigene ,allelic expression imbalance (AEI) ,fenoterol ,Therapeutics. Pharmacology ,RM1-950 - Abstract
Organic cation transporter 1 (OCT1, SLC22A1) is localized in the sinusoidal membrane of human hepatocytes and mediates hepatic uptake of weakly basic or cationic drugs and endogenous compounds. Common amino acid substitutions in OCT1 were associated with altered pharmacokinetics and efficacy of drugs like sumatriptan and fenoterol. Recently, the common splice variant rs35854239 has also been suggested to affect OCT1 function. rs35854239 represents an 8 bp duplication of the donor splice site at the exon 7-intron 7 junction. Here we quantified the extent to which this duplication affects OCT1 splicing and, as a consequence, the expression and the function of OCT1. We used pyrosequencing and deep RNA-sequencing to quantify the effect of rs35854239 on splicing after minigene expression of this variant in HepG2 and Huh7 cells and directly in human liver samples. Further, we analyzed the effects of rs35854239 on OCT1 mRNA expression in total, localization and activity of the resulting OCT1 protein, and on the pharmacokinetics of sumatriptan and fenoterol. The 8 bp duplication caused alternative splicing in 38% (deep RNA-sequencing) to 52% (pyrosequencing) of the minigene transcripts when analyzed in HepG2 and Huh7 cells. The alternatively spliced transcript encodes for a truncated protein that after transient transfection in HEK293 cells was not localized in the plasma membrane and was not able to transport the OCT1 model substrate ASP+. In human liver, however, the alternatively spliced OCT1 transcript was detectable only at very low levels (0.3% in heterozygous and 0.6% in homozygous carriers of the 8 bp duplication, deep RNA-sequencing). The 8 bp duplication was associated with a significant reduction of OCT1 expression in the human liver, but explained only 9% of the general variability in OCT1 expression and was not associated with significant changes in the pharmacokinetics of sumatriptan and fenoterol. Therefore, the rs35854239 variant only partially changes splicing, causing moderate changes in OCT1 expression and may be of only limited therapeutic relevance.
- Published
- 2021
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20. Effects of Genetic Polymorphism in CYP2D6, CYP2C19, and the Organic Cation Transporter OCT1 on Amitriptyline Pharmacokinetics in Healthy Volunteers and Depressive Disorder Patients.
- Author
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Matthaei, Johannes, Brockmöller, Jürgen, Steimer, Werner, Pischa, Konstanze, Leucht, Stefan, Kullmann, Maria, Jensen, Ole, Ouethy, Typhaine, Tzvetkov, Mladen Vassilev, and Rafehi, Muhammad
- Subjects
MENTAL depression ,ORGANIC cation transporters ,AMITRIPTYLINE ,GENETIC polymorphisms ,ANTIPSYCHOTIC agents ,GENETIC variation ,ANTIDEPRESSANTS ,DULOXETINE - Abstract
The tricyclic antidepressant amitriptyline is frequently prescribed but its use is limited by its narrow therapeutic range and large variation in pharmacokinetics. Apart from interindividual differences in the activity of the metabolising enzymes cytochrome P450 (CYP) 2D6 and 2C19, genetic polymorphism of the hepatic influx transporter organic cation transporter 1 (OCT1) could be contributing to interindividual variation in pharmacokinetics. Here, the impact of OCT1 genetic variation on the pharmacokinetics of amitriptyline and its active metabolite nortriptyline was studied in vitro as well as in healthy volunteers and in depressive disorder patients. Amitriptyline and nortriptyline were found to inhibit OCT1 in recombinant cells with IC
50 values of 28.6 and 40.4 µM. Thirty other antidepressant and neuroleptic drugs were also found to be moderate to strong OCT1 inhibitors with IC50 values in the micromolar range. However, in 35 healthy volunteers, preselected for their OCT1 genotypes, who received a single dose of 25 mg amitriptyline, no significant effects on amitriptyline and nortriptyline pharmacokinetics could be attributed to OCT1 genetic polymorphism. In contrast, the strong impact of the CYP2D6 genotype on amitriptyline and nortriptyline pharmacokinetics and of the CYP2C19 genotype on nortriptyline was confirmed. In addition, acylcarnitine derivatives were measured as endogenous biomarkers for OCT1 activity. The mean plasma concentrations of isobutyrylcarnitine and 2-methylbutyrylcarnitine were higher in participants with two active OCT1 alleles compared to those with zero OCT1 activity, further supporting their role as endogenous in vivo biomarkers for OCT1 activity. A moderate reduction in plasma isobutyrylcarnitine concentrations occurred at the time points at which amitriptyline plasma concentrations were the highest. In a second, independent study sample of 50 patients who underwent amitriptyline therapy of 75 mg twice daily, a significant trend of increasing amitriptyline plasma concentrations with decreasing OCT1 activity was observed (p = 0.018), while nortriptyline plasma concentrations were unaffected by the OCT1 genotype. Altogether, this comprehensive study showed that OCT1 activity does not appear to be a major factor determining amitriptyline and nortriptyline pharmacokinetics and that hepatic uptake occurs mainly through other mechanisms. [ABSTRACT FROM AUTHOR]- Published
- 2021
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21. Organic Cation Transporter 1 an Intestinal Uptake Transporter: Fact or Fiction?
- Author
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Christoph Wenzel, Marek Drozdzik, and Stefan Oswald
- Subjects
organic cation transporter 1 ,intestine ,human ,gene expression ,protein abundance ,localization ,Therapeutics. Pharmacology ,RM1-950 - Abstract
Intestinal transporter proteins are known to affect the pharmacokinetics and in turn the efficacy and safety of many orally administered drugs in a clinically relevant manner. This knowledge is especially well-established for intestinal ATP-binding cassette transporters such as P-gp and BCRP. In contrast to this, information about intestinal uptake carriers is much more limited although many hydrophilic or ionic drugs are not expected to undergo passive diffusion but probably require specific uptake transporters. A transporter which is controversially discussed with respect to its expression, localization and function in the human intestine is the organic cation transporter 1 (OCT1). This review article provides an up-to-date summary on the available data from expression analysis as well as functional studies in vitro, animal findings and clinical observations. The current evidence suggests that OCT1 is expressed in the human intestine in small amounts (on gene and protein levels), while its cellular localization in the apical or basolateral membrane of the enterocytes remains to be finally defined, but functional data point to a secretory function of the transporter at the basolateral membrane. Thus, OCT1 should not be considered as a classical uptake transporter in the intestine but rather as an intestinal elimination pathway for cationic compounds from the systemic circulation.
- Published
- 2021
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22. Influence of YES1 Kinase and Tyrosine Phosphorylation on the Activity of OCT1
- Author
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Muhammad Erfan Uddin, Dominique A. Garrison, Kyeongmin Kim, Yan Jin, Eric D. Eisenmann, Kevin M. Huang, Alice A. Gibson, Zeping Hu, Alex Sparreboom, and Shuiying Hu
- Subjects
organic cation transporter 1 ,YES1 kinase ,tyrosine kinase inhibitors ,drug-transporter interactions ,post-translational modification ,Therapeutics. Pharmacology ,RM1-950 - Abstract
Organic cation transporter 1 (OCT1) is a transporter that regulates the hepatic uptake and subsequent elimination of diverse cationic compounds. Although OCT1 has been involved in drug-drug interactions and causes pharmacokinetic variability of many prescription drugs, details of the molecular mechanisms that regulate the activity of OCT1 remain incompletely understood. Based on an unbiased phospho-proteomics screen, we identified OCT1 as a tyrosine-phosphorylated transporter, and functional validation studies using genetic and pharmacological approaches revealed that OCT1 is highly sensitive to small molecules that target the protein kinase YES1, such as dasatinib. In addition, we found that dasatinib can inhibit hepatic OCT1 function in mice as evidenced from its ability to modulate levels of isobutyryl L-carnitine, a hepatic OCT1 biomarker identified from a targeted metabolomics analysis. These findings provide novel insight into the post-translational regulation of OCT1 and suggest that caution is warranted with polypharmacy regimes involving the combined use of OCT1 substrates and kinase inhibitors that target YES1.
- Published
- 2021
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23. Effect of 7-ketocholesterol incorporation on substrate binding affinity and turnover rate of the organic cation transporter 2 (OCT2).
- Author
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Xiu F, Console L, Indiveri C, Su S, Wang T, and Visentin M
- Subjects
- Humans, Organic Cation Transporter 2 metabolism, Molecular Docking Simulation, HEK293 Cells, Organic Cation Transporter 1, Ketocholesterols pharmacology, Organic Cation Transport Proteins
- Abstract
The organic cation transporter 2 (OCT2) is pivotal in the renal elimination of several positively charged molecules. OCT2 mode of transport is profoundly influenced by the level of membrane cholesterol. The aim of this study was to investigate the effect of oxidized cholesterol on OCT2 transport activity in human embryonic kidney 293 cells stably transfected with OCT2 (OCT2-HEK293) and in primary renal proximal tubular epithelial cells (RPTEC). Cholesterol was exchanged with 7-ketocholesterol, the main product of cholesterol auto-oxidation, by exposing cells to sterol-saturated methyl-β-cyclodextrin (mβcd). After a 30 min-exposure, approximately 50% of the endogenous cholesterol was replaced by 7-ketocholesterol without significant changes in total sterol level. In the presence of 7-ketocholesterol, [
3 H]1-methyl-4-phenylpyridinium (MPP+ ) uptake was significantly reduced in both cell lines. 7-ketocholesterol incorporation did not affect lipid raft integrity, nor OCT2 surface expression and spatial organization. The inhibitory effect of 7-ketocholesterol on MPP+ uptake was abolished by the presence of MPP+ in the trans-compartment. In the presence of 7-ketocholesterol, both Kt and Vmax of MPP+ influx decreased. Molecular docking using OCT2 structure in outward occluded conformation showed overlapping poses and similar binding energies between cholesterol and 7-ketocholesterol. The thermal stability of OCT2 was not changed when cholesterol was replaced with 7-ketocholesterol. We conclude that 7-ketocholesterol confers a higher rigidity to the carrier by reducing its conformational entropy, arguably as a result of changes in plasma membrane physical properties, thereby facilitating the achievement of a higher affinity state at the expense of the mobility and overall cycling rate of the transporter., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)- Published
- 2024
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24. Role of Organic Cation Transporter 1, OCT1 in the Pharmacokinetics and Toxicity of cis-Diammine(pyridine)chloroplatinum(II) and Oxaliplatin in Mice
- Author
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Li, Shuanglian, Chen, Ying, Zhang, Shuzhong, More, Swati S, Huang, Xiaozhu, and Giacomini, Kathleen M
- Subjects
Biomedical and Clinical Sciences ,Clinical Sciences ,Digestive Diseases ,Liver Disease ,Animals ,Cells ,Cultured ,HEK293 Cells ,Humans ,Kidney ,Male ,Mice ,Mice ,Knockout ,Organic Cation Transporter 1 ,Organoplatinum Compounds ,Oxaliplatin ,Tissue Distribution ,OCT I ,pharmacokinetics ,platinum agent ,toxicity ,transporter ,Pharmacology and Pharmaceutical Sciences ,Pharmacology & Pharmacy ,Pharmacology and pharmaceutical sciences - Abstract
PurposeThe goal of this study was to test the hypothesis that by controlling intracellular uptake, organic cation transporter 1, Oct1 is a key determinant of the disposition and toxicity of cis-diammine(pyridine)chloroplatinum(II)(CDPCP) and oxaliplatin.MethodsPharmacokinetics, tissue accumulation and toxicity of CDPCP and oxaliplatin were compared between Oct1-/- and wild-type mice.ResultsAfter intravenous administration, hepatic and intestinal accumulation of CDPCP was 2.7-fold and 3.9-fold greater in Oct1 wild-type mice (p < 0.001). Deletion of Oct1 resulted in a significantly decreased clearance (0.444 ± 0.0391 ml/min*kg versus 0.649 ± 0.0807 ml/min*kg in wild-type mice, p < 0.05) and volume distribution (1.90 ± 0.161 L/kg versus 3.37 ± 0.196 L/kg in wild-type mice, p < 0.001). Moreover, Oct1 deletion resulted in more severe off-target toxicities in CDPCP-treated mice. Histologic examination of the liver and measurements of liver function indicated that the level of hepatic toxicity was mild and reversible, but was more apparent in the wild-type mice. In contrast, the effect of Oct1 on the pharmacokinetics and toxicity of oxaliplatin in the mice was minimal.ConclusionsOur study suggests that Oct1 plays an important role in the pharmacokinetics, tissue distribution and toxicity of CDPCP, but not oxaliplatin.
- Published
- 2011
25. CO2 Permeability of Rat Hepatocytes and Relation of CO2 Permeability to CO2 Production
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Mariela Arias-Hidalgo, Qinggong Yuan, Fabrizio Carta, Claudiu T. Supuran, Gerolf Gros, and Volker Endeward
- Subjects
Rat hepatocytes ,CO2 permeability ,Oxygen consumption ,Intracellular carbonic anhydrase activity ,Extracellular carbonic anhydrase inhibitor ,Organic cation transporter 1 ,Cholesterol ,Gas channels ,Physiology ,QP1-981 ,Biochemistry ,QD415-436 - Abstract
Background/Aims: It has been described that cells in culture with very low oxidative metabolism possess a low CO2 membrane permeability, PCO2, of ∼ 0.01 cm/s. On the other hand, cardiomyocytes and mitochondria with extremely high rates of O2 consumption exhibit very high CO2 membrane permeabilities of 0.1 and 0.3 cm/s, repectively. To ascertain that this represents a systematic relationship, we determine here PCO2 of hepatocytes, which exhibit an intermediate rate of O2 consumption. Methods: We isolated intact hepatocytes with vitalities of ∼ 70% from rat liver and measured their CO2 permeability by the previously published mass spectrometric 18O exchange technique. Results: We find a PCO2 of hepatocytes of 0.03 cm/s in the presence of FC5-208A and verapamil. FC5-208A was necessary to inhibt extracellular carbonic anhydrase, and verapamil was necessary to inhibit intracellular uptake of FC5-208A by the organic cation transporter OCT1 of hepatocytes. Conclusion: Rat hepatocytes with their intermediate rate of oxygen consumption also possess an intermediate CO2 permeability. From pairs of data for five types of cells/organelles, we find an excellent positive linear correlation between PCO2 and metabolic rate, suggesting an adaptation of PCO2 to the rate of O2 consumption.
- Published
- 2018
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26. Reports from Tsinghua University Describe Recent Advances in Antidiabetic Agents (Structural insights into human organic cation transporter 1 transport and inhibition).
- Abstract
A recent report from Tsinghua University discusses the advances in understanding the human organic cation transporter 1 (hOCT1) and its role in the uptake of various organic cations, including drugs. The study focuses on the interaction between hOCT1 and metformin, a commonly used medication for type 2 diabetes, as well as the inhibitory effects of spironolactone, a steroid analog. The researchers used cryo-electron microscopy to analyze the structures of hOCT1 in different conformational states and provide insights into the transport mechanism of metformin and the inhibition mechanism of spironolactone. The findings contribute to a better understanding of hOCT1's function and may aid in the development of new therapeutic agents targeting this transporter. [Extracted from the article]
- Published
- 2024
27. Citrus fruit‐derived flavonoid naringenin and the expression of hepatic organic cation transporter 1 protein in diabetic rats treated with metformin.
- Author
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Mato Mofo, Edith P., Essop, M. Faadiel, and Owira, Peter M. O.
- Subjects
- *
METFORMIN , *ORGANIC cation transporters , *CARRIER proteins , *HESPERIDIN , *NARINGENIN , *SPRAGUE Dawley rats , *GLUCOSE tolerance tests - Abstract
Naringenin possesses many pharmacological effects and may modulate metformin disposition. The purpose of this study was to evaluate the role of naringenin on hepatic expression of organic cation transporter 1 (OCT1) protein and its associated effects on metformin‐associated hyperlactataemia in diabetes. Forty‐nine male Sprague Dawley rats randomly assigned to seven groups (n = 7) were orally treated daily with 3.0 mL/kg body‐weight (BW) of distilled water (group 1) or 60 mg/kg BW of naringenin (groups 2 and 5) or 250 mg/kg BW of metformin (groups 3 and 6), respectively, dissolved in distilled water. Similarly, group 7 was given metformin and naringenin. Groups 4, 5, 6 and 7 were administered intraperitoneally with streptozotocin at a single dose of 60 mg/kg BW to induce diabetes. Glucose tolerance tests were performed. The animals were killed after 8 weeks of treatment, blood was collected, and livers excised for further biochemical analysis. Lowered body‐weight, increased polydipsia and reduced hepatic glycogen concentrations were observed in diabetic rats compared to controls. Naringenin only significantly decreased plasma lactate levels, while metformin only or with naringenin significantly increased plasma lactate levels in diabetic compared to non‐treated diabetic animals. Metformin only but not naringenin significantly increased plasma lactate levels in non‐diabetic compared to control rats. Furthermore, naringenin with or without metformin but not metformin only significantly increased hepatic organic cation transporter 1 (OCT1) expression in diabetic compared to non‐treated diabetic rats. Contrastingly, metformin only but not naringenin significantly increased hepatic OCT1 expression in non‐diabetic rats compared to controls. Diabetic rats treated with metformin exhibited significantly increased plasma metformin concentrations compared to non‐diabetic but naringenin significantly dropped this parameter. Conversely, hepatic metformin concentrations were significantly lower in diabetic rats treated with metformin compared to non‐diabetic rats but significantly increased when naringenin was added. These results suggest that naringenin ameliorated hyperglycaemia‐induced reduction in hepatic OCT1 expression leading to metformin accumulation and increased lactic acid production. [ABSTRACT FROM AUTHOR]
- Published
- 2020
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28. High affinity of 4‐(4‐(dimethylamino)styryl)‐N‐methylpyridinium transport for assessing organic cation drugs in hepatocellular carcinoma cells.
- Author
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Jinakote, Metee, Ontawong, Atcharaporn, Soodvilai, Sunhapas, Pimta, Jeerawat, Pasachan, Tipthida, Chatsudthipong, Varanuj, and Srimaroeng, Chutima
- Subjects
- *
ORGANIC cation transporters , *HEPATOCELLULAR carcinoma , *CATIONS , *METFORMIN , *DRUG interactions , *LIVER cells - Abstract
Human organic cation transporter 1 (hOCT1) and human organic cation transporter 3 (hOCT3) are highly expressed in hepatocytes and play important roles in cationic drug absorption, distribution, and elimination. A previous study demonstrated that downregulation of hOCT1 and hOCT3 mRNA was related to hepatocellular carcinoma (HepG2) prognosis and severity. Whether these transporters expressed in HepG2 cells serve for cationic drug delivery has not been investigated. Besides radioactive transport, options for assessing hOCTs in hepatocytes are limited. This study clarified the significant roles of hOCTs in HepG2 by comparing cationic fluorescent 4‐(4‐(dimethylamino)styryl)‐N‐methylpyridinium (ASP+) with traditional [3H]‐1‐methyl‐4‐phenylpyridinium (MPP+). The results showed ASP+ was preferably transported into HepG2 compared to [3H]‐MPP+ with high affinity and a high maximal transport rate. Selective transport of ASP+ mediated by hOCTs was influenced by extracellular pH, temperature, and membrane depolarization, corresponding to hOCT1 and hOCT3 expressions. Furthermore, transport of cationic drugs, metformin, and paclitaxel in HepG2 cells was blunted by OCT inhibitors, suggesting that hOCT1 and hOCT3 expressed in HepG2 cells exhibit notable impacts on cationic drug actions. The fluorescent ASP+‐based in vitro model may also provide a rapid and powerful analytical tool for further screening of cationic drug actions and interactions with hOCTs, particularly hOCT1 and hOCT3 in hepatocellular carcinoma. [ABSTRACT FROM AUTHOR]
- Published
- 2020
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29. Substrates and Inhibitors of the Organic Cation Transporter 3 and Comparison with OCT1 and OCT2
- Author
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Lukas Gebauer, Ole Jensen, Jürgen Brockmöller, and Christof Dücker
- Subjects
Organic Cation Transport Proteins ,Cations ,Drug Discovery ,Organic Cation Transporter 1 ,Organic Cation Transporter 2 ,Molecular Medicine ,Biological Transport - Abstract
Organic cation transporters (OCTs) 1, 2, and 3 facilitate cellular uptake of structurally diverse endogenous and exogenous substances. However, their substrate and inhibitor specificity are not fully understood. We performed a broad
- Published
- 2022
30. Effects of single-nucleotide polymorphism on the pharmacokinetics and pharmacodynamics of metformin
- Author
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Shaoqian Li, Bo Xu, Shangzhi Fan, Bo Kang, Lijing Deng, Danjun Chen, Bo Yang, Fan Tang, Zunbo He, Yong Xue, and Jie-Can Zhou
- Subjects
Glucose ,Diabetes Mellitus, Type 2 ,Organic Cation Transporter 1 ,Humans ,Hypoglycemic Agents ,Membrane Transport Proteins ,Organic Cation Transporter 2 ,Pharmacology (medical) ,General Medicine ,General Pharmacology, Toxicology and Pharmaceutics ,Polymorphism, Single Nucleotide ,Metformin - Abstract
Metformin has been recognized as the first-choice drug for type 2 diabetes mellitus (T2DM). The potency of metformin in the treatment of type 2 diabetes has always been in the spotlight and shown significant individual differences. Based on previous studies, the efficacy of metformin is related to the single-nucleotide polymorphisms of transporter genes carried by patients, amongst which a variety of gene polymorphisms of transporter and target protein genes affect the effectiveness and adverse repercussion of metformin.Here, we reviewed the current knowledge about gene polymorphisms impacting metformin efficacy based on transporter and drug target proteins.The reason for the difference in clinical drug potency of metformin can be attributed to the gene polymorphism of drug transporters and drug target proteins in the human body. Substantial evidence shows that genetic polymorphisms in transporters such as organic cation transporter 1 (OCT1) and organic cation transporter 2 (OCT2) affect the glucose-lowering effectiveness of metformin. However, optimization of individualized dosing regimens of metformin is necessary to clarify the role of several polymorphisms.
- Published
- 2022
31. Functional Expression of Carnitine/Organic Cation Transporter 1 in Murine Choroid Plexus.
- Author
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Ishimoto T, Nakamichi N, Taguchi T, Nishiyama M, and Kato Y
- Subjects
- Animals, Mice, Male, Mice, Inbred C57BL, Symporters, Choroid Plexus metabolism, Mice, Knockout, Organic Cation Transport Proteins metabolism, Organic Cation Transport Proteins genetics, Ergothioneine metabolism, Ergothioneine cerebrospinal fluid
- Abstract
Membrane transporters expressed in the choroid plexus (CP) are involved in the transport of substances between the blood and cerebrospinal fluid (CSF). Carnitine/organic cation transporter 1 (OCTN1, also known as SLC22A4) is expressed in rodent CP; however, its specific roles in blood-CSF transport remain unclear. Therefore, in this study, we aimed to evaluate the potential role of OCTN1 in the elimination of substances from CSF. Tritium-labeled ergothioneine ([
3 H]ERGO), a typical in vivo substrate of OCTN1, was injected into the lateral ventricles of wild-type and octn1 gene knockout (octn1-/- ) mice. Clearance of [3 H]ERGO from CSF was higher than that of the bulk flow marker, [14 C]mannitol, in wild-type mice. However, [3 H]ERGO clearance was significantly lower in octn1-/- mice than in wild-type mice. Furthermore, OCTN1 expression in CP was determined via immunohistochemical analysis. CP/CSF ratio of [3 H]ERGO was significantly lower in octn1-/- mice than in wild-type mice. These results suggest that OCTN1 is functionally expressed in CP and involved in the elimination of ERGO from CSF in mice.- Published
- 2024
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32. Structural basis of organic cation transporter-3 inhibition
- Author
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Basavraj Khanppnavar, Julian Maier, Freja Herborg, Ralph Gradisch, Erika Lazzarin, Dino Luethi, Jae-Won Yang, Chao Qi, Marion Holy, Kathrin Jäntsch, Oliver Kudlacek, Klaus Schicker, Thomas Werge, Ulrik Gether, Thomas Stockner, Volodymyr M. Korkhov, and Harald H. Sitte
- Subjects
Catecholamines ,Multidisciplinary ,Organic Cation Transport Proteins ,Cations ,Organic Cation Transporter 1 ,Humans ,Organic Cation Transporter 2 ,General Physics and Astronomy ,Biological Transport ,General Chemistry ,Corticosterone ,General Biochemistry, Genetics and Molecular Biology - Abstract
Organic cation transporters (OCTs) facilitate the translocation of catecholamines, drugs and xenobiotics across the plasma membrane in various tissues throughout the human body. OCT3 plays a key role in low-affinity, high-capacity uptake of monoamines in most tissues including heart, brain and liver. Its deregulation plays a role in diseases. Despite its importance, the structural basis of OCT3 function and its inhibition has remained enigmatic. Here we describe the cryo-EM structure of human OCT3 at 3.2 Å resolution. Structures of OCT3 bound to two inhibitors, corticosterone and decynium-22, define the ligand binding pocket and reveal common features of major facilitator transporter inhibitors. In addition, we relate the functional characteristics of an extensive collection of previously uncharacterized human genetic variants to structural features, thereby providing a basis for understanding the impact of OCT3 polymorphisms., Nature Communications, 13 (1), ISSN:2041-1723
- Published
- 2022
33. No significant influence of OCT1 genotypes on the pharmacokinetics of morphine in adult surgical patients
- Author
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Ida Kuhlmann, Kim Brøsen, Kenn Dornonville de la Cour, Troels K Bergmann, Mette Marie Hougaard Christensen, Tore Bjerregaard Stage, Stine Thorhauge Zwisler, Per Damkier, Anders Gadegaard Jensen, Rasmus Hjelmar Petersen, Flemming Nielsen, and Morten Overgaard
- Subjects
Male ,medicine.medical_specialty ,Time Factors ,Genotype ,Toxicology ,Gastroenterology ,M6G ,Bolus (medicine) ,Pharmacokinetics ,Internal medicine ,pharmacodynamics ,medicine ,Humans ,organic cation transporter 1 ,Adverse effect ,Genotyping ,Aged ,Pharmacology ,Morphine Derivatives ,Pain, Postoperative ,Morphine ,business.industry ,Genetic Variation ,morphine ,General Medicine ,Middle Aged ,Confidence interval ,Analgesics, Opioid ,Area Under Curve ,Pharmacodynamics ,Female ,business ,pharmacokinetics ,Octamer Transcription Factor-1 ,medicine.drug - Abstract
We investigated the impact of genetic variants in OCT1 (SLC22A1) on morphine, morphine-3-glucuronide (M3G) and morphine-6-glucuronide (M6G) pharmacokinetics in adult patients scheduled for major surgery. Blood samples were taken before and 5, 10, 15, 30, 45, 60 and 90 min after a bolus of morphine (0.15 mg/kg). Patients were genotyped for the genetic variants (rs12208357, rs34059508, rs72552763 and rs34130495) in OCT1. Eighty-six patients completed the trial. The mean difference (95% confidence interval) for dose adjusted morphine, M3G and M6G AUC was 0.9 (−0.7–2.4), −5.9 (−11.8 to −0.03) and −1.1 (−2.5–0.4) h/L*10 −6, respectively, in patients with two reduced function alleles compared to patients with no reduced function alleles in OCT1. Accordingly, the (AUC M3G/Dose)/(AUC morphine/Dose) and (AUC M6G/Dose)/(AUC morphine/Dose) ratio was reduced, −1.8 (−3.2 to −0.4) and −0.4 (−0.7 to −0.03), respectively, when comparing the same groups. OCT1 variants had no influence on the experience of pain, adverse events or the number of PCA doses used. In conclusion, genetic variants in OCT1 had a small and clinically unimportant impact on the exposure of morphine after intravenous administration. Our results do not support pre-emptive genotyping for OCT1 prior to morphine administration in patients scheduled for major surgery.
- Published
- 2021
34. Evaluation of Drug-Drug Interactions of Ensitrelvir, a SARS-CoV-2 3CL Protease Inhibitor, With Transporter Substrates Based on In Vitro and Clinical Studies.
- Author
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Shimizu R, Matsuzaki T, Oka R, Sonoyama T, Fukuhara T, Kuwata A, Matsuo Y, and Kubota R
- Subjects
- Humans, ATP Binding Cassette Transporter, Subfamily G, Member 2 metabolism, SARS-CoV-2, Rosuvastatin Calcium pharmacokinetics, Protease Inhibitors, Neoplasm Proteins metabolism, Membrane Transport Proteins metabolism, Drug Interactions, ATP Binding Cassette Transporter, Subfamily B, Member 1 metabolism, Digoxin pharmacokinetics, Enzyme Inhibitors, Organic Cation Transporter 1, Biological Transport, Solute Carrier Organic Anion Transporter Family Member 1B3 metabolism, COVID-19, Organic Anion Transporters, Metformin pharmacokinetics
- Abstract
Drug-drug interaction potentials of ensitrelvir, a novel oral inhibitor of 3C-like protease of severe acute respiratory syndrome coronavirus 2, for drug transporters were evaluated by in vitro and clinical studies. The target drug transporters assessed were P-glycoprotein (P-gp), breast cancer resistance protein (BCRP), organic anion transporting polypeptide (OATP) 1B1, OATP1B3, organic anion transporter (OAT) 1, OAT3, organic cation transporter (OCT) 1, OCT2, and multidrug and toxin extrusion 1 and 2K. In vitro study revealed that ensitrelvir is a substrate for P-gp and BCRP and inhibits P-gp, BCRP, OATP1B1, OATP1B3, OCT1, and OAT3. Based on these results, a clinical drug-drug interaction study to evaluate the effect of ensitrelvir on the pharmacokinetics of P-gp, BCRP, OATP1B1, OATP1B3, and OCT1 substrates was conducted with a cocktail approach using digoxin (P-gp substrate), rosuvastatin (BCRP, OATP1B1, and OATP1B3 substrate), and metformin (OCT1 substrate). The cocktail was administered first, and after the washout period, the cocktail was coadministered with 500 mg of ensitrelvir. No treatment-emergent adverse events were observed. Pharmacokinetic analyses demonstrated that the ratios (90% confidence intervals) of "cocktail with ensitrelvir" to "cocktail without ensitrelvir" for maximum plasma concentration and area under the plasma concentration-time curve were, respectively, 2.17 (1.72-2.73) and 1.31 (1.13-1.52) for digoxin, 1.97 (1.73-2.25) and 1.65 (1.47-1.84) for rosuvastatin, and 1.03 (0.91-1.16) and 1.02 (0.94-1.11) for metformin. The results indicate that the exposure levels of digoxin and rosuvastatin increased when coadministered with ensitrelvir, but those of metformin were not changed. In conclusion, ensitrelvir has an impact on the exposure levels of P-gp, BCRP, OATP1B1, and OATP1B3 substrates., (© 2023 The Authors. The Journal of Clinical Pharmacology published by Wiley Periodicals LLC on behalf of American College of Clinical Pharmacology.)
- Published
- 2023
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35. Stereoselectivity in the Membrane Transport of Phenylethylamine Derivatives by Human Monoamine Transporters and Organic Cation Transporters 1, 2, and 3
- Author
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Lukas Gebauer, Muhammad Rafehi, and Jürgen Brockmöller
- Subjects
Norepinephrine ,Phenylephrine ,Catecholamines ,Epinephrine ,Synephrine ,Cations ,Organic Cation Transporter 1 ,Humans ,Membrane Transport Proteins ,Molecular Biology ,Biochemistry ,Octopamine ,monoamine transporters ,organic cation transporters ,stereoselective drug transport ,chiral HPLC ,phenylethylamines ,neurotransmitter transport - Abstract
Stereoselectivity is well known and very pronounced in drug metabolism and receptor binding. However, much less is known about stereoselectivity in drug membrane transport. Here, we characterized the stereoselective cell uptake of chiral phenylethylamine derivatives by human monoamine transporters (NET, DAT, and SERT) and organic cation transporters (OCT1, OCT2, and OCT3). Stereoselectivity differed extensively between closely related transporters. High-affinity monoamine transporters (MATs) showed up to 2.4-fold stereoselective uptake of norepinephrine and epinephrine as well as of numerous analogs. While NET and DAT preferentially transported (S)-norepinephrine, SERT preferred the (R)-enantiomer. In contrast, NET and DAT showed higher transport for (R)-epinephrine and SERT for (S)-epinephrine. Generally, MAT stereoselectivity was lower than expected from their high affinity to several catecholamines and from the high stereoselectivity of some inhibitors used as antidepressants. Additionally, the OCTs differed strongly in their stereoselectivity. While OCT1 showed almost no stereoselective uptake, OCT2 was characterized by a roughly 2-fold preference for most (R)-enantiomers of the phenylethylamines. In contrast, OCT3 transported norphenylephrine and phenylephrine with 3.9-fold and 3.3-fold preference for their (R)-enantiomers, respectively, while the para-hydroxylated octopamine and synephrine showed no stereoselective OCT3 transport. Altogether, our data demonstrate that stereoselectivity is highly transporter-to-substrate specific and highly diverse even between homologous transporters.
- Published
- 2022
- Full Text
- View/download PDF
36. CO2 Permeability of Rat Hepatocytes and Relation of CO2 Permeability to CO2 Production.
- Author
-
Arias-Hidalgo, Mariela, Yuan, Qinggong, Carta, Fabrizio, Supuran, Claudiu T., Gros, Gerolf, and Endeward, Volker
- Subjects
- *
CARBON dioxide analysis , *ORGANIC cation transporters , *CARBONIC anhydrase , *LIVER disease diagnosis , *LABORATORY rats - Abstract
It has been described that cells in culture with very low oxidative metabolism possess a low CO2 membrane permeability, PCO2, of ∼ 0.01 cm/s. On the other hand, cardiomyocytes and mitochondria with extremely high rates of O2 consumption exhibit very high CO2 membrane permeabilities of 0.1 and 0.3 cm/s, repectively. To ascertain that this represents a systematic relationship, we determine here PCO2 of hepatocytes, which exhibit an intermediate rate of O2 consumption.Background/Aims: We isolated intact hepatocytes with vitalities of ∼ 70% from rat liver and measured their CO2 permeability by the previously published mass spectrometric 18O exchange technique.Methods: We find a PCO2 of hepatocytes of 0.03 cm/s in the presence of FC5-208A and verapamil. FC5-208A was necessary to inhibt extracellular carbonic anhydrase, and verapamil was necessary to inhibit intracellular uptake of FC5-208A by the organic cation transporter OCT1 of hepatocytes.Results: Rat hepatocytes with their intermediate rate of oxygen consumption also possess an intermediate CO2 permeability. From pairs of data for five types of cells/organelles, we find an excellent positive linear correlation between PCO2 and metabolic rate, suggesting an adaptation of PCO2 to the rate of O2 consumption. [ABSTRACT FROM AUTHOR]Conclusion: - Published
- 2018
- Full Text
- View/download PDF
37. Substrates of the Human Brain Proton-Organic Cation Antiporter and Comparison with Organic Cation Transporter 1 Activities
- Author
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David A. Doetsch, Salim Ansari, Ole Jensen, Lukas Gebauer, Christof Dücker, Jürgen Brockmöller, and Alexandra Sachkova
- Subjects
organic cation transporter ,proton-organic cation antiporter ,hCMEC/D3 cells ,blood–brain barrier ,orphan transporter ,Organic Cation Transport Proteins ,Organic Chemistry ,Organic Cation Transporter 1 ,Brain ,Biological Transport ,General Medicine ,Antiporters ,Catalysis ,Computer Science Applications ,Inorganic Chemistry ,Cations ,Humans ,Protons ,Physical and Theoretical Chemistry ,Molecular Biology ,Spectroscopy ,Octamer Transcription Factor-1 - Abstract
Many organic cations (OCs) may be transported through membranes by a genetically still uncharacterized proton-organic cation (H + OC) antiporter. Here, we characterized an extended substrate spectrum of this antiporter. We studied the uptake of 72 drugs in hCMEC/D3 cells as a model of the human blood–brain barrier. All 72 drugs were tested with exchange transport assays and the transport of 26 of the drugs was studied in more detail concerning concentration-dependent uptake and susceptibility to specific inhibitors. According to exchange transport assays, 37 (51%) drugs were good substrates of the H + OC antiporter. From 26 drugs characterized in more detail, 23 were consistently identified as substrates of the H + OC antiporter in six different assays and transport kinetic constants could be identified with intrinsic clearances between 0.2 (ephedrine) and 201 (imipramine) mL × minute−1 × g protein−1. Excellent substrates of the H + OC antiporter were no substrates of organic cation transporter OCT1 and vice versa. Good substrates of the H + OC antiporter were more hydrophobic and had a lower topological polar surface area than non-substrates or OCT1 substrates. These data and further research on the H + OC antiporter may result in a better understanding of pharmacokinetics, drug–drug interactions and variations in pharmacokinetics.
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- 2022
- Full Text
- View/download PDF
38. Free Cholesterol Affects the Function and Localization of Human Na
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Jessica Y, Idowu and Bruno, Hagenbuch
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Bile Acids and Salts ,Taurocholic Acid ,Cholesterol ,Liver ,Symporters ,Non-alcoholic Fatty Liver Disease ,Organic Cation Transporter 1 ,Humans ,Organic Anion Transporters, Sodium-Dependent ,Peptides ,Octamer Transcription Factor-1 - Abstract
Non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH) are associated with obesity. They are accompanied by increased levels of free cholesterol in the liver. Most free cholesterol resides within the plasma membrane. We assessed the impact of adding or removing free cholesterol on the function and localization of two hepatocellular uptake transporters: the Na
- Published
- 2022
39. Localization of Xenobiotic Transporters Expressed at the Human Blood-Testis Barrier
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Raymond K. Hau, Robert R. Klein, Stephen H. Wright, and Nathan J. Cherrington
- Subjects
Pharmacology ,Male ,Cations ,Organic Cation Transporter 1 ,Pharmaceutical Science ,Humans ,Articles ,Blood-Testis Barrier ,Xenobiotics - Abstract
The blood-testis barrier (BTB) is formed by basal tight junctions between adjacent Sertoli cells (SCs) of the seminiferous tubules and acts as a physical barrier to protect developing germ cells in the adluminal compartment from reproductive toxicants. Xenobiotics, including antivirals, male contraceptives, and cancer chemotherapeutics, are known to cross the BTB, although the mechanisms that permit barrier circumvention are generally unknown. This study used immunohistological staining of human testicular tissue to determine the site of expression for xenobiotic transporters that facilitate transport across the BTB. Organic anion transporter (OAT) 1, OAT2, and organic cation transporter, novel (OCTN) 1 primarily localized to the basal membrane of SCs, whereas OCTN2, multidrug resistance protein (MRP) 3, MRP6, and MRP7 localized to SC basal membranes and peritubular myoid cells (PMCs) surrounding the seminiferous tubules. Concentrative nucleoside transporter (CNT) 2 localized to Leydig cells (LCs), PMCs, and SC apicolateral membranes. Organic cation transporter (OCT) 1, OCT2, and OCT3 mostly localized to PMCs and LCs, although there was minor staining in developing germ cells for OCT3. Organic anion transporting polypeptide (OATP) 1A2, OATP1B1, OATP1B3, OATP2A1, OATP2B1, and OATP3A1-v2 localized to SC basal membranes with diffuse staining for some transporters. Notably, OATP1C1 and OATP4A1 primarily localized to LCs. Positive staining for multidrug and toxin extrusion protein (MATE) 1 was only observed throughout the adluminal compartment. Definitive staining for CNT1, OAT3, MATE2, and OATP6A1 was not observed. The location of these transporters is consistent with their involvement in the movement of xenobiotics across the BTB. Altogether, the localization of these transporters provides insight into the mechanisms of drug disposition across the BTB and will be useful in developing tools to overcome the pharmacokinetic and pharmacodynamic difficulties presented by the BTB. SIGNIFICANCE STATEMENT: Although the total mRNA and protein expression of drug transporters in the testes has been explored, the localization of many transporters at the blood-testis barrier (BTB) has not been determined. This study applied immunohistological staining in human testicular tissues to identify the cellular localization of drug transporters in the testes. The observations made in this study have implications for the development of drugs that can effectively use transporters expressed at the basal membranes of Sertoli cells to bypass the BTB.
- Published
- 2022
40. Cloning and Functional Characterization of Dog OCT1 and OCT2: Another Step in Exploring Species Differences in Organic Cation Transporters
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Marleen Julia Meyer, Simon Falk, Sarah Römer, Clarissa Prinzinger, Sabine Tacke, Joachim Geyer, Stefan Simm, and Mladen Vassilev Tzvetkov
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Organic Cation Transport Proteins ,Organic Chemistry ,Organic Cation Transporter 1 ,Organic Cation Transporter 2 ,General Medicine ,Catalysis ,Computer Science Applications ,Inorganic Chemistry ,Mice ,Dogs ,HEK293 Cells ,Species Specificity ,Cations ,Animals ,Humans ,Cloning, Molecular ,Physical and Theoretical Chemistry ,organic cation transporter ,SLC22A1 ,SLC22A2 ,species differences ,ortholog comparison ,gene structure ,metformin ,trospium ,fenoterol ,ipratropium ,butylscopolamine ,Molecular Biology ,Spectroscopy ,Fenoterol - Abstract
OCT1 and OCT2 are polyspecific membrane transporters that are involved in hepatic and renal drug clearance in humans and mice. In this study, we cloned dog OCT1 and OCT2 and compared their function to the human and mouse orthologs. We used liver and kidney RNA to clone dog OCT1 and OCT2. The cloned and the publicly available RNA-Seq sequences differed from the annotated exon-intron structure of OCT1 in the dog genome CanFam3.1. An additional exon between exons 2 and 3 was identified and confirmed by sequencing in six additional dog breeds. Next, dog OCT1 and OCT2 were stably overexpressed in HEK293 cells and the transport kinetics of five drugs were analyzed. We observed strong differences in the transport kinetics between dog and human orthologs. Dog OCT1 transported fenoterol with 12.9-fold higher capacity but 14.3-fold lower affinity (higher KM) than human OCT1. Human OCT1 transported ipratropium with 5.2-fold higher capacity but 8.4-fold lower affinity than dog OCT1. Compared to human OCT2, dog OCT2 showed 10-fold lower transport of fenoterol and butylscopolamine. In conclusion, the functional characterization of dog OCT1 and OCT2 reported here may have implications when using dogs as pre-clinical models as well as for drug therapy in dogs.
- Published
- 2022
- Full Text
- View/download PDF
41. Regulation of host and virus genes by neuronal miR-138 favours herpes simplex virus 1 latency
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Fujun Hou, Dongli Pan, Jean M. Pesola, George M. Church, Xuewei Yang, Jenna Morris-Love, Priya Raja, David M. Knipe, Qiongyan Wang, Hyung Suk Oh, Emilia A. H. Vanni, Boqiang Sun, Xiaofeng Yu, Seamus McCarron, Donald M. Coen, and Alex Hay-Man Ng
- Subjects
Gene Expression Regulation, Viral ,Male ,Microbiology (medical) ,Small interfering RNA ,Ubiquitin-Protein Ligases ,viruses ,Immunology ,Herpesvirus 1, Human ,Biology ,medicine.disease_cause ,Applied Microbiology and Biotechnology ,Microbiology ,Article ,Immediate-Early Proteins ,Mice ,03 medical and health sciences ,Transcription (biology) ,Gene expression ,Virus latency ,Genetics ,medicine ,Animals ,Humans ,Gene silencing ,030304 developmental biology ,Neurons ,0303 health sciences ,Gene knockdown ,030306 microbiology ,Organic Cation Transporter 1 ,Herpes Simplex ,Cell Biology ,medicine.disease ,eye diseases ,Virus Latency ,Cell biology ,MicroRNAs ,Herpes simplex virus ,Lytic cycle ,Host-Pathogen Interactions ,RNA, Viral ,sense organs - Abstract
MicroRNA miR-138, which is highly expressed in neurons, represses herpes simplex virus 1 (HSV-1) lytic cycle genes by targeting viral ICP0 messenger RNA, thereby promoting viral latency in mice. We found that overexpressed miR-138 also represses lytic processes independently of ICP0 in murine and human neuronal cells; therefore, we investigated whether miR-138 has targets besides ICP0. Using genome-wide RNA sequencing/photoactivatable ribonucleoside-enhanced crosslinking and immunoprecipitation followed by short interfering RNA knockdown of candidate targets, we identified the host Oct-1 and Foxc1 messenger mRNAs as miR-138’s targets, whose gene products are transcription factors important for HSV-1 replication in neuronal cells. OCT-1 has a known role in the initiation of HSV transcription. Overexpression of FOXC1, which was not known to affect HSV-1, promoted HSV-1 replication in murine neurons and ganglia. CRISPR–Cas9 knockout of FOXC1 reduced viral replication, lytic gene expression and miR-138 repression in murine neuronal cells. FOXC1 also collaborated with ICP0 to decrease heterochromatin on viral genes and compensated for the defect of an ICP0-null virus. In summary, miR-138 targets ICP0, Oct-1 and Foxc1 to repress HSV-1 lytic cycle genes and promote epigenetic gene silencing, which together enable favourable conditions for latent infection. Genome-wide RNA sequencing/PAR-CLIP and short interfering RNA knockdown are combined to show that neuronal microRNA miR-138 targets ICP0, Oct-1 and Foxc1 to repress HSV-1 lytic cycle genes and promote epigenetic gene silencing, thereby favouring viral latency.
- Published
- 2021
42. Role of human organic cation transporter-1 (OCT-1/SLC22A1) in modulating the response to metformin in patients with type 2 diabetes
- Author
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Fizalah Kawoosa, Zafar A. Shah, Shariq R. Masoodi, Asif Amin, Roohi Rasool, Khalid M. Fazili, Abid Hamid Dar, Asif Lone, and Samir ul Bashir
- Subjects
Molecular Docking Simulation ,Diabetes Mellitus, Type 2 ,Endocrinology, Diabetes and Metabolism ,Cations ,Organic Cation Transporter 1 ,Humans ,Hypoglycemic Agents ,General Medicine ,Polymorphism, Single Nucleotide ,Metformin - Abstract
Background Organic cation transporter 1 primarily governs the action of metformin in the liver. There are considerable inter-individual variations in metformin response. In light of this, it is crucial to obtain a greater understanding of the influence of OCT1 expression or polymorphism in the context of variable responses elicited by metformin treatment. Results We observed that the variable response to metformin in the responders and non-responders is independent of isoform variation and mRNA expression of OCT-1. We also observed an insignificant difference in the serum metformin levels of the patient groups. Further, molecular docking provided us with an insight into the hotspot regions of OCT-1 for metformin binding. Genotyping of these regions revealed SNPs 156T>C and 1222A>G in both the groups, while as 181C>T and 1201G>A were found only in non-responders. The 181T>C and 1222A>G changes were further found to alter OCT-1 structure in silico and affect metformin transport in vitro which was illustrated by their effect on the activation of AMPK, the marker for metformin activity. Conclusion Taken together, our results corroborate the role of OCT-1 in the transport of metformin and also point at OCT1 genetic variations possibly affecting the transport of metformin into the cells and hence its subsequent action in responders and non-responders.
- Published
- 2022
43. Evaluation of the Impact of Ritlecitinib on Organic Cation Transporters Using Sumatriptan and Biomarkers as Probes.
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Wang X, Purohit V, Dowty ME, Rodrigues D, Luo L, Mathialagan S, Carey W, Plotka A, Kalluru H, Melissa O, Kaplan J, Huh Y, Vourvahis M, and Wolk RM
- Subjects
- Adult, Humans, Organic Cation Transporter 1, Biomarkers, Cations metabolism, HEK293 Cells, Organic Cation Transport Proteins, Sumatriptan
- Abstract
Ritlecitinib, an inhibitor of Janus kinase 3 and hepatocellular carcinoma family kinases, is in development as potential treatment for several inflammatory diseases. In vitro studies presented ritlecitinib as an inhibitor of hepatic organic cation transporter (OCT) 1, renal transporters OCT2 and multidrug and toxin extrusion (MATE) proteins 1/2K using multiple substrates, and ritlecitinib's major inactive metabolite M2, as an inhibitor of OCT1. A clinical interaction study with an OCT1 drug probe (sumatriptan) and relevant probe biomarkers for OCT/MATE was conducted to assess the effect of ritlecitinib on these transporters in healthy adult participants. The selectivity of sumatriptan for OCT1 was confirmed through a series of in vitro uptake assays. A simple static model was used to help contextualize the observed changes in sumatriptan area under the plasma concentration-time curve (AUC). Coadministration of a single 400-mg dose of ritlecitinib increased sumatriptan AUC from time 0 to infinity (AUC
inf ) by ≈30% relative to a single 25-mg sumatriptan administration alone. When administered 8 hours after a ritlecitinib dose, sumatriptan AUCinf increased by ≈50% relative to sumatriptan given alone. Consistent with OCT1 inhibition, the AUC from time 0 to 24 hours of isobutyryl-L-carnitine decreased by ≈15% after ritlecitinib. Based on the evaluation of the renal clearance of N1 -methylnicotinamide, ritlecitinib does not exert clinically meaningful inhibition on renal OCT2 or MATE1/2K. This study confirmed that ritlecitinib and M2 are inhibitors of OCT1 but not OCT2 or MATE1/2K in healthy adults., (© 2023 Pfizer Inc. The Journal of Clinical Pharmacology published by Wiley Periodicals LLC on behalf of American College of Clinical Pharmacology.)- Published
- 2023
- Full Text
- View/download PDF
44. Differences in Metformin and Thiamine Uptake between Human and Mouse Organic Cation Transporter 1: Structural Determinants and Potential Consequences for Intrahepatic Concentrations
- Author
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Tina Seitz, Barbara Zdrazil, Sarah Römer, Jürgen Brockmöller, Stefan Oswald, Christoph Wenzel, Jochen Gaedcke, Mladen V. Tzvetkov, Alzbeta Tuerkova, and Marleen Julia Meyer
- Subjects
Male ,Protein Conformation, alpha-Helical ,Recombinant Fusion Proteins ,Drug Evaluation, Preclinical ,Pharmaceutical Science ,Pharmacology ,030226 pharmacology & pharmacy ,Mice ,Structure-Activity Relationship ,03 medical and health sciences ,0302 clinical medicine ,Species Specificity ,Pharmacokinetics ,medicine ,Animals ,Humans ,Thiamine ,Organic cation transport proteins ,Sequence Homology, Amino Acid ,biology ,Chemistry ,HEK 293 cells ,Organic Cation Transporter 1 ,Transporter ,Transfection ,Metformin ,Recombinant Proteins ,Rats ,3. Good health ,Transmembrane domain ,HEK293 Cells ,Liver ,030220 oncology & carcinogenesis ,Hepatocytes ,biology.protein ,medicine.drug - Abstract
The most commonly used oral antidiabetic drug, metformin, is a substrate of the hepatic uptake transporter OCT1 (gene name SLC22A1). However, OCT1 deficiency leads to more pronounced reductions of metformin concentrations in mouse than in human liver. Similarly, the effects of OCT1 deficiency on the pharmacokinetics of thiamine were reported to differ between human and mouse. Here, we compared the uptake characteristics of metformin and thiamine between human and mouse OCT1 using stably transfected human embryonic kidney 293 cells. The affinity for metformin was 4.9-fold lower in human than in mouse OCT1, resulting in a 6.5-fold lower intrinsic clearance. Therefore, the estimated liver-to-blood partition coefficient is only 3.34 in human compared with 14.4 in mouse and may contribute to higher intrahepatic concentrations in mice. Similarly, the affinity for thiamine was 9.5-fold lower in human than in mouse OCT1. Using human-mouse chimeric OCT1, we showed that simultaneous substitution of transmembrane helices TMH2 and TMH3 resulted in the reversal of affinity for metformin. Using homology modeling, we suggest several explanations, of which a different interaction of Leu155 (human TMH2) compared with Val156 (mouse TMH2) with residues in TMH3 had the strongest experimental support. In conclusion, the contribution of human OCT1 to the cellular uptake of thiamine and especially of metformin may be much lower than that of mouse OCT1. This may lead to an overestimation of the effects of OCT1 on hepatic concentrations in humans when using mouse as a model. In addition, comparative analyses of human and mouse orthologs may help reveal mechanisms of OCT1 transport. SIGNIFICANCE STATEMENT: OCT1 is a major hepatic uptake transporter of metformin and thiamine, but this study reports strong differences in the affinity for both compounds between human and mouse OCT1. Consequently, intrahepatic metformin concentrations could be much higher in mice than in humans, impacting metformin actions and representing a strong limitation of using rodent animal models for predictions of OCT1-related pharmacokinetics and efficacy in humans. Furthermore, OCT1 transmembrane helices TMH2 and TMH3 were identified to confer the observed species-specific differences in metformin affinity.
- Published
- 2020
45. A Multiplexed HILIC-MS/HRMS Assay for the Assessment of Transporter Inhibition Biomarkers in Phase I Clinical Trials: Isobutyryl-Carnitine as an Organic Cation Transporter (OCT1) Biomarker
- Author
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Lina Luo, Manoli Vourvahis, Sumathy Mathialagan, Christopher L Holliman, A. David Rodrigues, Lauren Horlbogen, Chester Costales, and Ragu Ramanathan
- Subjects
Drug ,Analyte ,Organic Cation Transport Proteins ,media_common.quotation_subject ,Pharmacology ,010402 general chemistry ,01 natural sciences ,Analytical Chemistry ,Carnitine ,medicine ,Humans ,Drug Interactions ,Enzyme Inhibitors ,media_common ,Organic cation transport proteins ,Clinical Trials, Phase I as Topic ,biology ,Chemistry ,Hydrophilic interaction chromatography ,010401 analytical chemistry ,Organic Cation Transporter 1 ,Organic Cation Transporter 2 ,Transporter ,Metformin ,0104 chemical sciences ,Valid Biomarker ,biology.protein ,Biomarker (medicine) ,Biomarkers ,medicine.drug - Abstract
There is a growing interest in using endogenous compounds as drug transporter biomarkers to facilitate drug-drug interaction (DDI) risk assessment in early phase I clinical trials. Compared to other drug transporters, however, no valid biomarker for hepatic organic cation transporter (OCT) 1 has been described to date. The present work represents the first report of an endogenous compound, isobutyryl-l-carnitine (IBC), as a potential clinical OCT1 biomarker for DDI assessment. A hydrophilic interaction chromatography (HILIC)-mass spectrometry/high resolution mass spectrometry (MS/HRMS) assay with a simple sample preparation method was developed. The assay is capable of simultaneously quantifying multiple endogenous compounds, including IBC, thiamine, N1-methylnicotinamide (1-NMN), creatinine, carnitine, and metformin, which is a probe for OCT1 and OCT2 and MATE1 and MATE2K (multidrug and toxin extrusion proteins) in clinical studies. The HRMS assay was fit-for-purpose validated in human plasma and demonstrated good linearity, accuracy, and precision for all analytes. It was further applied to two phase I clinical trials to evaluate potential biomarkers for OCT1 and additional cation transporters (renal OCT2, MATE1, and MATE2K). The clinical data demonstrated that plasma IBC changes correlated well with in vitro data and supported its use as a liver OCT1 biomarker. The described HILIC-MS/HRMS assay can be used as a "biomarker cocktail" to simultaneously assess clinical DDI risk for the inhibition of OCT1/2 and MATEs in clinical studies with new drug candidates.
- Published
- 2020
46. Citrus fruit‐derived flavonoid naringenin and the expression of hepatic organic cation transporter 1 protein in diabetic rats treated with metformin
- Author
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M. Faadiel Essop, Peter M. O. Owira, and Edith P. Mato Mofo
- Subjects
Blood Glucose ,Male ,Naringenin ,Citrus ,medicine.medical_specialty ,endocrine system diseases ,Toxicology ,030226 pharmacology & pharmacy ,Streptozocin ,Diabetes Mellitus, Experimental ,Rats, Sprague-Dawley ,03 medical and health sciences ,chemistry.chemical_compound ,0302 clinical medicine ,Internal medicine ,Diabetes mellitus ,medicine ,Animals ,Hypoglycemic Agents ,Lactic Acid ,Flavonoids ,Pharmacology ,Organic cation transport proteins ,biology ,Organic Cation Transporter 1 ,nutritional and metabolic diseases ,food and beverages ,General Medicine ,Streptozotocin ,medicine.disease ,Metformin ,Rats ,Lactic acid ,Endocrinology ,Liver ,chemistry ,Lactic acidosis ,Flavanones ,biology.protein ,medicine.symptom ,Polydipsia ,030217 neurology & neurosurgery ,medicine.drug - Abstract
Naringenin possesses many pharmacological effects and may modulate metformin disposition. The purpose of this study was to evaluate the role of naringenin on hepatic expression of organic cation transporter 1 (OCT1) protein and its associated effects on metformin-associated hyperlactataemia in diabetes. Forty-nine male Sprague Dawley rats randomly assigned to seven groups (n = 7) were orally treated daily with 3.0 mL/kg body-weight (BW) of distilled water (group 1) or 60 mg/kg BW of naringenin (groups 2 and 5) or 250 mg/kg BW of metformin (groups 3 and 6), respectively, dissolved in distilled water. Similarly, group 7 was given metformin and naringenin. Groups 4, 5, 6 and 7 were administered intraperitoneally with streptozotocin at a single dose of 60 mg/kg BW to induce diabetes. Glucose tolerance tests were performed. The animals were killed after 8 weeks of treatment, blood was collected, and livers excised for further biochemical analysis. Lowered body-weight, increased polydipsia and reduced hepatic glycogen concentrations were observed in diabetic rats compared to controls. Naringenin only significantly decreased plasma lactate levels, while metformin only or with naringenin significantly increased plasma lactate levels in diabetic compared to non-treated diabetic animals. Metformin only but not naringenin significantly increased plasma lactate levels in non-diabetic compared to control rats. Furthermore, naringenin with or without metformin but not metformin only significantly increased hepatic organic cation transporter 1 (OCT1) expression in diabetic compared to non-treated diabetic rats. Contrastingly, metformin only but not naringenin significantly increased hepatic OCT1 expression in non-diabetic rats compared to controls. Diabetic rats treated with metformin exhibited significantly increased plasma metformin concentrations compared to non-diabetic but naringenin significantly dropped this parameter. Conversely, hepatic metformin concentrations were significantly lower in diabetic rats treated with metformin compared to non-diabetic rats but significantly increased when naringenin was added. These results suggest that naringenin ameliorated hyperglycaemia-induced reduction in hepatic OCT1 expression leading to metformin accumulation and increased lactic acid production.
- Published
- 2020
47. The Role of
- Author
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Sweny de S M, Fernandes, Luciana P C, Leitão, Amanda de N, Cohen-Paes, Laura P A, Gellen, Lucas F, Pastana, Darlen C, de Carvalho, Antônio A C, Modesto, Ana C A, da Costa, Alayde V, Wanderley, Carlos H V de, Lima, Esdras E B, Pereira, Marianne R, Fernandes, Rommel M R, Burbano, Paulo P, de Assumpção, Sidney E B Dos, Santos, and Ney P C Dos, Santos
- Subjects
Polymorphism, Genetic ,Adolescent ,Organic Cation Transporter 1 ,Black People ,Humans ,Precursor Cell Lymphoblastic Leukemia-Lymphoma ,Pyrophosphatases ,Child - Abstract
In Brazil, Acute lymphoid leukemia (ALL) is the leading cause of cancer deaths in children and adolescents. Treatment toxicity is one of the reasons for stopping chemotherapy. Amerindian genomic ancestry is an important factor for this event due to fluctuations in frequencies of genetic variants, as in the
- Published
- 2021
48. Amino acids in transmembrane helix 1 confer major functional differences between human and mouse orthologs of the polyspecific membrane transporter OCT1
- Author
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Marleen J. Meyer, Pascale C.F. Schreier, Mert Basaran, Stefaniia Vlasova, Tina Seitz, Jürgen Brockmöller, Barbara Zdrazil, and Mladen V. Tzvetkov
- Subjects
drug transport ,species differences ,molecular modeling ,membrane transport ,Organic Cation Transporter 1 ,Cell Biology ,transmembrane domain ,Biochemistry ,structure-function ,Molecular Docking Simulation ,Mice ,HEK293 Cells ,transporter ,Animals ,Humans ,Amino Acid Sequence ,Catecholamine Plasma Membrane Transport Proteins ,Molecular Biology ,SLC22A1 ,Fenoterol - Abstract
Organic cation transporter 1 (OCT1) is a membrane transporter that affects hepatic uptake of cationic and weakly basic drugs. OCT1 transports structurally highly diverse substrates. The mechanisms conferring this polyspecificity are unknown. Here, we analyzed differences in transport kinetics between human and mouse OCT1 orthologs to identify amino acids that contribute to the polyspecificity of OCT1. Following stable transfection of HEK293 cells, we observed more than twofold differences in the transport kinetics of 22 out of 28 tested substrates. We found that the β2-adrenergic drug fenoterol was transported with eightfold higher affinity but at ninefold lower capacity by human OCT1. In contrast, the anticholinergic drug trospium was transported with 11-fold higher affinity but at ninefold lower capacity by mouse Oct1. Using human-mouse chimeric constructs and site-directed mutagenesis, we identified nonconserved amino acids Cys36 and Phe32 as responsible for the species-specific differences in fenoterol and trospium uptake. Substitution of Cys36 (human) to Tyr36 (mouse) caused a reversal of the affinity and capacity of fenoterol but not trospium uptake. Substitution of Phe32 to Leu32 caused reversal of trospium but not fenoterol uptake kinetics. Comparison of the uptake of structurally similar β2-adrenergics and molecular docking analyses indicated the second phenol ring, 3.3 to 4.8 Å from the protonated amino group, as essential for the affinity for fenoterol conferred by Cys36. This is the first study to report single amino acids as determinants of OCT1 polyspecificity. Our findings suggest that structure-function data of OCT1 is not directly transferrable between substrates or species.
- Published
- 2021
49. MPP
- Author
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Tamara A M, Mocking, Hubert J, Sijben, Yimé W, Vermeulen, Adriaan P, IJzerman, and Laura H, Heitman
- Subjects
1-Methyl-4-phenylpyridinium ,HEK293 Cells ,Gene Expression Regulation ,Organic Cation Transport Proteins ,Herbicides ,Electric Impedance ,Organic Cation Transporter 1 ,Biological Transport, Active ,Humans ,Organic Cation Transporter 2 ,Biological Transport - Abstract
The organic cation transporters OCT1-3 (
- Published
- 2021
50. Atypical Substrates of the Organic Cation Transporter 1
- Author
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Kyra-Elisa Maria Redeker, Ole Jensen, Lukas Gebauer, Marleen Julia Meyer-Tönnies, and Jürgen Brockmöller
- Subjects
HEK293 Cells ,Liver ,Cations ,Organic Cation Transporter 1 ,Humans ,Biological Transport ,OCT1 ,SLC22A1 ,organic cation transporter ,substrates ,genetic polymorphisms ,Molecular Biology ,Biochemistry - Abstract
The human organic cation transporter 1 (OCT1) is expressed in the liver and mediates hepatocellular uptake of organic cations. However, some studies have indicated that OCT1 could transport neutral or even anionic substrates. This capability is interesting concerning protein-substrate interactions and the clinical relevance of OCT1. To better understand the transport of neutral, anionic, or zwitterionic substrates, we used HEK293 cells overexpressing wild-type OCT1 and a variant in which we changed the putative substrate binding site (aspartate474) to a neutral amino acid. The uncharged drugs trimethoprim, lamivudine, and emtricitabine were good substrates of hOCT1. However, the uncharged drugs zalcitabine and lamotrigine, and the anionic levofloxacin, and prostaglandins E2 and F2α, were transported with lower activity. Finally, we could detect only extremely weak transport rates of acyclovir, ganciclovir, and stachydrine. Deleting aspartate474 had a similar transport-lowering effect on anionic substrates as on cationic substrates, indicating that aspartate474 might be relevant for intra-protein, rather than substrate-protein, interactions. Cellular uptake of the atypical substrates by the naturally occurring frequent variants OCT1*2 (methionine420del) and OCT1*3 (arginine61cysteine) was similarly reduced, as it is known for typical organic cations. Thus, to comprehensively understand the substrate spectrum and transport mechanisms of OCT1, one should also look at organic anions.
- Published
- 2022
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