Identification and Functional Characterization of Novel Nonsynonymous Variants in the Human Multidrug and Toxin Extrusion 2-K

Abstract

This study was performed to identify genetic polymorphisms in multidrug and toxin extrusion 2-K (MATE2-K, SLC47A2), a proton/ organic cation antiporter that plays a role in the transport of organic cations across the apical membrane in kidney epithelial cells into the urine, and to demonstrate their effects on MATE2-K functions in vitro. Four of the thirty single nucleotide polymorphisms (SNPs) we identified in three ethnic groups (Caucasian, African American, and Japanese) were novel [308C>G (P103R), c.487-8C>T, 818A>G (Y273C), and c.1018+14T>C]. The transport activities of the prototypical substrates, tetraethylammonium and metformin, for four nonsynonymous SNPs (P103R, P162L, G211V, and Y273C) were significantly different from those of the wild-type. In particular, transport activity was higher in P103R than in the wild-type, which is the first time elevated transport activity was demonstrated due to these coding SNPs. Kinetic analysis revealed that P103R had a higher V max value, whereas Y273C had a lower value than that in the wild-type. Cell surface protein expression levels were higher for P103R than for the wild-type, whereas Y273C expression was decreased. Immunofluorescence analysis revealed that the P103R protein was localized to the plasma membrane, whereas Y273C showed cytoplasmic localization. Therefore, the difference in transport activities between P103R and Y273C variants was suggested to be responsible for the different protein expression levels observed at the plasma membrane. Four nonsynonymous SNPs in this study showed relatively low allelic frequencies (0.5 to 2.1%), but these were associated with markedly reduced or increased MATE2-K function.

Nucleosome Positioning and Gene Regulation of the SGLT2 Gene in the Renal Proximal Tubular Epithelial Cells

“…Deletion constructs [22320/118, 21587/118, 2485/118, 2154/118, 244/118, and del-(251/237)] were generated by In-Fusion cloning or the QuikChange II site-directed mutagenesis method (Supplemental Table 1) using the 23185/118 construct as a template. The sequences of these plasmids were confirmed by direct sequencing using primers (Supplemental Table 2) described previously (Nishimura et al, 2014).…”

Population diversity of three variants of the SLC47A2 gene (MATE2-K transporter) in Mexican Mestizos and Native Americans

“…One of the most relevant clinical gene variants is rs12943590 (g.-130G>A), which is in the 5´-UTR promoter region. The presence of the A allele produces a "gain-of-function" and increase of metformin depuration; thus, patients with G/A and A/A genotypes present higher levels of glycated hemoglobin (HbA1c) and higher metformin dose requirements for these patients [5][6][7][8][9][10]. Interestingly, the allele A frequency varies along with worldwide human populations (13.1 to 49.5%) [11].…”

Histone H3 Lysine 4 Trimethylation, Lysine 27 Trimethylation, and Lysine 27 Acetylation Contribute to the Transcriptional Repression of Solute Carrier Family 47 Member 2 in Renal Cell Carcinoma

“…Little is known about the regulation mechanism of SLC47A2. Some single-nucleotide polymorphisms have been found to affect drug transport function of MATE2K (Kajiwara et al, 2009;Choi et al, 2011;Chung et al, 2013;Stocker et al, 2013;Nishimura et al, 2014). Myeloid zinc finger 1 may play a repressive role in SLC47A2 expression (Choi et al, 2011).…”