Functional Characterization of the Human Organic Cation Transporter 2 Variant p.270Ala>Ser

Abstract

ABSTRACT:The organic cation transporter 2 (OCT2, SLC22A2) plays an important role for renal drug elimination. Recent clinical studies indicate an impact of the frequent nonsynonymous c.808G>T (p.270Ala>Ser) polymorphism on renal clearance of metformin and the extent of the metformin-cimetidine interaction. The role of this polymorphism for renal disposition of endogenous compounds and drugs other than metformin has not been investigated. In addition, it is unclear whether the observed genotype dependence of an OCT2-mediated drug-drug interaction might occur also with other OCT inhibitors. To address these issues, we generated human embryonic kidney cells stably expressing wild-type OCT2 or the p.270Ala>Ser variant. No differences in protein expression levels and membrane incorporation pattern were observed between the two cell lines. The p.270Ala>Ser variant significantly impaired uptake kinetics of 1-methyl-4-phenylpyridinium, dopamine, norepinephrine, and propranolol. V max values were significantly reduced for uptake of all four compounds mediated by the p.270Ala>Ser variant compared with wild-type OCT2. In addition, a significant difference in the affinity to wild-type and mutant OCT2 was observed for dopamine (K m dopamine: 932 ؎ 77 versus 1285 ؎ 132 M). Moreover, out of a set of 27 compounds p.270Ala>Ser OCT2 was significantly less sensitive to inhibition by cimetidine, flurazepam, metformin, mexiletine, propranolol, and verapamil than wild-type OCT2 (e.g., for propranolol: IC 50 wild type versus p.270Ala>Ser 189 versus 895 M, P < 0.001). Our results indicate that the common OCT2 c.808G>T single nucleotide polymorphism significantly alters uptake of endogenous compounds and drugs. Moreover, for selected compounds the extent of OCT2-mediated drug interactions could depend on OCT2 c.808G>T genotype.

Organic Cation Transporter Variation and Response to Smoking Cessation Therapies

“…77 Consistent with most of the clinical data except the study of Chen et al 73 , the in vitro functional literature suggests that the effect of the rs316019 minor allele is associated with significant reductions in the transport of model OCT2 substrates. 78,79 Thus ~19%-28% of European, East Asian, and Yoruban ancestry populations may be carriers of a reduced function OCT2 protein. Further in vivo and in vitro research on OCT2 variation and effects on drug disposition is needed.…”

SLC22A2is associated with tubular creatinine secretion and bias of estimated GFR in renal transplantation

“…The other, a missense rs316019, is the most frequent coding variant in the SLC22A2 gene and is also the best functionally characterized. This polymorphism in the exon 4 results in an Ala270Ser amino acid substitution with functional consequences for the protein and was associated with impaired transport of OCT2 substrates in vitro (8,15,48,57,61). Because genotyping of rs316019 was technically not possible in this study, we searched for another SNP to use as a proxy.…”

Фармакогенетичні Аспекти Дії Метформіну У Хворих На цукровий Діабет 2-Го Типу

“…У кількох дослідженнях вказується на те, що ген SLC22A2 є ви-сокополіморфним за своєю природою [40][41][42][43]. Zolk et al [44] виявили, що такий варіант гена SLC22A2, як 808G > T (270Ala > Ser), сприяє зниженню біо-трансформації ліків.…”