Substrate specificity of MATE1 and MATE2-K, human multidrug and toxin extrusions/H+-organic cation antiporters

Abstract

The substrate specificities of human (h) multidrug and toxin extrusion (MATE) 1 and hMATE2-K were examined to find functional differences between these two transporters by the transfection of the cDNA of hMATE1 and hMATE2-K into HEK293 cells. Western blotting revealed specific signals for hMATE1 and hMATE2-K consistent with a size of 50 and 40kDa, respectively, in the transfectants as well as human renal brush-border membranes under reducing conditions. In the presence of oppositely directed H(+)-gradient, the transport activities of various compounds such as tetraethylammonium, 1-methyl-4-phenylpyridinium, cimetidine, metformin, creatinine, guanidine, procainamide, and topotecan were stimulated in hMATE1- and hMATE2-K-expressing cells. In addition to cationic compounds, anionic estrone sulfate, acyclovir, and ganciclovir were also recognized as substrates of these transporters. Kinetic analyses demonstrated the Michaelis-Menten constants for the hMATE1-mediated transport of tetraethylammonium, 1-methyl-4-phenylpyridinium, cimetidine, metformin, guanidine, procainamide, topotecan, estrone sulfate, acycrovir, and ganciclovir to be (in mM) 0.38, 0.10, 0.17, 0.78, 2.10, 1.23, 0.07, 0.47, 2.64, and 5.12, respectively. Those for hMATE2-K were 0.76, 0.11, 0.12, 1.98, 4.20, 1.58, 0.06, 0.85, 4.32, and 4.28, respectively. Although their affinity for hMATE1 and hMATE2-K was similar, the zwitterionic cephalexin and cephradine were revealed to be specific substrates of hMATE1, but not of hMATE2-K. Levofloxacin and ciprofloxacin were not transported, but were demonstrated to be potent inhibitors of these transporters. These results suggest that hMATE1 and hMATE2-K function together as a detoxication system, by mediating the tubular secretion of intracellular ionic compounds across the brush-border membranes of the kidney.

Identification of multidrug and toxin extrusion (MATE1 and MATE2-K) variants with complete loss of transport activity

“…[15][16][17] On the other hand, Shikata et al 25 reported that OCT1 and OCT2 polymorphisms contribute little to the clinical efficacy of metformin in Japanese. Previously, we demonstrated that metformin is a good substrate not only for OCT2 but also for MATE1 and MATE2-K. 19,26 Therefore, the SNPs of MATE1 and MATE2-K genes identified in this study may be involved in the interindividual difference in the renal clearance of metformin in Japanese. However, as the allelic frequencies of MATE1 and MATE2-K SNPs are not very high, these SNPs cannot fully account for the large interindividual variation in the renal clearance of metformin.…”

“…[15][16][17] Metformin showed large interindividual variation in renal clearance, and a potential genetic contribution by the renal transporter was speculated. 18 Because metformin is also a superior substrate for MATE1 and MATE2-K, 10,19 polymorphisms of MATE1 and MATE2-K genes may be involved in the interindividual difference in the renal clearance. We have recently identified a single nucleotide polymorphism (SNP) in the promoter region of MATE1 (À32G4A), which causes a decrease in Sp1 binding and promoter activity of approximately 50%.…”

Characterization of the Inhibitory Effects ofN-Butylpyridinium Chloride and Structurally Related Ionic Liquids on Organic Cation Transporters 1/2 and Human Toxic Extrusion Transporters 1/2-K In Vitro and In Vivo

“…Metformin is a comparatively low-affinity substrate for hOCT1, hOCT2, hMATE1, and hMATE2-K, with K t values of 1.47, 0.99, 0.78, and 1.98 mM, respectively (Koepsell et al, 2007;Tanihara et al, 2007). As determined here, NBuPy-Cl blocks both OCTs and MATEs with IC 50 values in the low micromolar range.…”

Targeting Effect of Traditional Chinese Medicine

“…This may be one of the reasons for its toxicity reducing effect. In spite of above well known transporters there are some transporters such as Mate1-2, RLIP76, and aquaporin, may play a role in meridian guide effect (Tanihara 2007, Ohta et al, 2009Singhal, 2009). For example, carbamazepine is an active drug for epilepsy, and it has drug-resistant phenomenon.…”