Dataset Information

Role of organic cation transporter 3 (SLC22A3) and its missense variants in the pharmacologic action of metformin.

ABSTRACT: The goals of this study were to determine the role of organic cation transporter 3 (OCT3) in the pharmacological action of metformin and to identify and functionally characterize genetic variants of OCT3 with respect to the uptake of metformin and monoamines.For pharmacological studies, we evaluated metformin-induced activation of AMP-activated protein kinase, a molecular target of metformin. We used quantitative PCR and immunostaining to localize the transporter and isotopic uptake studies in cells transfected with OCT3 and its nonsynonymous genetic variants for functional analyses.Quantitative PCR and immunostaining showed that OCT3 was expressed high on the plasma membrane of skeletal muscle and liver, target tissues for metformin action. Both the OCT inhibitor, cimetidine, and OCT3-specific short hairpin RNA significantly reduced the activating effect of metformin on AMP-activated protein kinase. To identify genetic variants in OCT3, we used recent data from the 1000 Genomes and the Pharmacogenomics of Membrane Transporters projects. Six novel missense variants were identified. In functional assays, using various monoamines and metformin, three variants, T44M (c.131C>T), T400I (c.1199C>T) and V423F (c.1267G>T) showed altered substrate specificity. Notably, in cells expressing T400I and V423F, the uptakes of metformin and catecholamines were significantly reduced, but the uptakes of metformin, 1-methyl-4-phenylpyridinium and histamine by T44M were significantly increased more than 50%. Structural modeling suggested that these two variants may be located in the pore lining (T400) or proximal (V423) membrane-spanning helixes.Our study suggests that OCT3 plays a role in the therapeutic action of metformin and that genetic variants of OCT3 may modulate metformin and catecholamine action.

SUBMITTER: Chen L

PROVIDER: S-EPMC2976715 | biostudies-literature | 2010 Nov

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Role of organic cation transporter 3 (SLC22A3) and its missense variants in the pharmacologic action of metformin.

Chen Ligong L Pawlikowski Bradley B Schlessinger Avner A More Swati S SS Stryke Doug D Johns Susan J SJ Portman Michael A MA Chen Eugene E Ferrin Thomas E TE Sali Andrej A Giacomini Kathleen M KM

Pharmacogenetics and genomics 20101101 11

<h4>Objectives</h4>The goals of this study were to determine the role of organic cation transporter 3 (OCT3) in the pharmacological action of metformin and to identify and functionally characterize genetic variants of OCT3 with respect to the uptake of metformin and monoamines.<h4>Methods</h4>For pharmacological studies, we evaluated metformin-induced activation of AMP-activated protein kinase, a molecular target of metformin. We used quantitative PCR and immunostaining to localize the transport ...[more]

PMID: 20859243

Similar Datasets

Project description:The organic cation transporter (OCT) 3 is widely expressed in various organs in humans, and involved in the disposition of many exogenous and endogenous compounds. Several lines of evidence have suggested that OCT3 expressed in the brain plays an important role in the regulation of neurotransmission. Relative to wild-type (WT) animals, Oct3 knockout (KO) mice have displayed altered behavioral and neurochemical responses to psychostimulants such as amphetamine (AMPH) and methamphetamine. In the present study, both in vitro and in vivo approaches were utilized to explore potential mechanisms underlying the disparate neuropharmacological effects observed following AMPH exposure in Oct3 KO mice. In vitro uptake studies conducted in OCT3 transfected cells indicated that dextroamphetamine (d-AMPH) is not a substrate of OCT3. However, OCT3 was determined to be a high-capacity and low-affinity transporter for the neurotransmitters dopamine (DA), norepinephrine (NE), and serotonin (5-HT). Inhibition studies demonstrated that d-AMPH exerts relatively weak inhibitory effects on the OCT3-mediated uptake of DA, NE, 5-HT, and the model OCT3 substrate 4-(4-(dimethylamino)styryl)-N-methylpyridinium iodide. The IC(50) values were determined to be 41.5 +/- 7.5 and 24.1 +/- 7.0 microM for inhibiting DA and 5-HT uptake, respectively, while 50% inhibition of NE and 4-(4-(dimethylamino)styryl)-N-methylpyridinium iodide uptake was not achieved by even the highest concentration of d-AMPH applied (100 microM). Furthermore, the disposition of d-AMPH in various tissues including the brain, liver, heart, kidney, muscle, intestine, spleen, testis, uterus, and plasma were determined in both male and female Oct3 KO and WT mice. No significant difference was observed between either genotypes or sex in all tested organs and tissues. Our findings suggest that OCT3 is not a prominent factor influencing the disposition of d-AMPH. Additionally, based upon the inhibitory potency observed in vitro, d-AMPH is unlikely to inhibit the uptake of monoamines mediated by OCT3 in the brain. Differentiated neuropharmacological effects of AMPHs noted between Oct3 KO and WT mice appear to be due to the absence of Oct3 mediated uptake of neurotransmitters in the KO mice.

Dataset Information

Role of organic cation transporter 3 (SLC22A3) and its missense variants in the pharmacologic action of metformin.

Publications

Role of organic cation transporter 3 (SLC22A3) and its missense variants in the pharmacologic action of metformin.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets