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Open AccessArticle

Impact of Promoter Polymorphisms on the Transcriptional Regulation of the Organic Cation Transporter OCT1 (SLC22A1)

1
Institute of Clinical Pharmacology, University Medical Center, Georg-August-University, 37075 Göttingen, Germany
2
Institute of Pharmacology, Center of Drug Absorption and Transport (C_DAT), University Medicine Greifswald, 17487 Greifswald, Germany
*
Author to whom correspondence should be addressed.
J. Pers. Med. 2018, 8(4), 42; https://doi.org/10.3390/jpm8040042
Received: 14 September 2018 / Revised: 20 November 2018 / Accepted: 5 December 2018 / Published: 11 December 2018
(This article belongs to the Special Issue Personalized Medicine Based on Drug Transporter Genetic Heterogeneity)
The organic cation transporter 1 (OCT1, SLC22A1) is strongly expressed in the human liver and facilitates the hepatic uptake of drugs such as morphine, metformin, tropisetron, sumatriptan and fenoterol and of endogenous substances such as thiamine. OCT1 expression is inter-individually highly variable. Here, we analyzed SNPs in the OCT1 promoter concerning their potential contribution to the variability in OCT1 expression. Using electrophoretic mobility shift and luciferase reporter gene assays in HepG2, Hep3B, and Huh7 cell lines, we identified the SNPs −1795G>A (rs6935207) and −201C>G (rs58812592) as having effects on transcription factor binding and/or promoter activity. The A-allele of the −1795G>A SNP showed allele-specific binding of the transcription factor NF-Y leading to 2.5-fold increased enhancer activity of the artificial SV40 promoter. However, the −1795G>A SNP showed no significant effects on the native OCT1 promoter activity. Furthermore, the −1795G>A SNP was not associated with the pharmacokinetics of metformin, fenoterol, sumatriptan and proguanil in healthy individuals or tropisetron efficacy in patients undergoing chemotherapy. Allele-dependent differences in USF1/2 binding and nearly total loss in OCT1 promoter activity were detected for the G-allele of −201C>G, but the SNP is apparently very rare. In conclusion, common OCT1 promoter SNPs have only minor effects on OCT1 expression. View Full-Text
Keywords: OCT1; SNP; promoter; EMSA; luciferase reporter gene assay; expression; NF-Y OCT1; SNP; promoter; EMSA; luciferase reporter gene assay; expression; NF-Y
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Bokelmann, K.; Brockmöller, J.; Tzvetkov, M.V. Impact of Promoter Polymorphisms on the Transcriptional Regulation of the Organic Cation Transporter OCT1 (SLC22A1). J. Pers. Med. 2018, 8, 42.

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