TY - JOUR
T1 - Role of organic cation transporter 3 (SLC22A3) and its missense variants in the pharmacologic action of metformin
AU - Chen, Ligong
AU - Pawlikowski, Bradley
AU - Schlessinger, Avner
AU - More, Swati S.
AU - Stryke, Doug
AU - Johns, Susan J.
AU - Portman, Michael A.
AU - Chen, Eugene
AU - Ferrin, Thomas E.
AU - Sali, Andrej
AU - Giacomini, Kathleen M.
PY - 2010/11
Y1 - 2010/11
N2 - Objectives: 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. Methods: 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. Results: 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. Conclusion: 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.
AB - Objectives: 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. Methods: 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. Results: 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. Conclusion: 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.
KW - metformin
KW - monoamines
KW - muscle cells
KW - organic cation transporters
KW - pharmacogenomics
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UR - http://www.scopus.com/inward/citedby.url?scp=78049298630&partnerID=8YFLogxK
U2 - 10.1097/FPC.0b013e32833fe789
DO - 10.1097/FPC.0b013e32833fe789
M3 - Article
C2 - 20859243
AN - SCOPUS:78049298630
SN - 1744-6872
VL - 20
SP - 687
EP - 699
JO - Pharmacogenetics and genomics
JF - Pharmacogenetics and genomics
IS - 11
ER -