Expression of a Human Npt1/Slc17a1 Missense Variant Which Increases Urate Export
Expression of a Human Npt1/Slc17a1 Missense Variant Which Increases Urate Export
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增加尿酸盐输出的人类 Npt1/Slc17a1 错义变体的表达
DOI：
10.1080/15257770.2016.1149192
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发表时间：
2016
期刊：
影响因子：
--
通讯作者：
Y. Kanai and N. Shinomiya
中科院分区：
文献类型：
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作者：
Sakiyama;M.;H. Matsuo;S. Nagamori;W. Ling;Y. Kawamura;A. Nakayama;T. Higashino;T. Chiba;K. Ichida;Y. Kanai and N. Shinomiya
人钠依赖性磷酸共转运蛋白1型（NPT1/SLC17A1）是肾脏中的尿酸转运蛋白之一。我们最近的研究表明，npt1的常见错义变体I269T （rs1165196）可降低肾脏排泄不足痛风的风险。此外，我们证明了人类NPT1定位于肾近端小管的顶膜，I269T是增加NPT1介导的尿酸输出的功能获得变体。然而，I269T变异体增加尿酸出口量的机制尚不清楚。因此，我们使用xenopusoocyte表达系统进行了人类NPT1的免疫染色和功能分析。为了比较269I（野生型）和269T（变异型）人NPT1在卵母细胞膜上的表达水平，用抗人NPT1抗体进行免疫染色。因此，我们发现NPT1 I269T变体没有改变人类NPT1膜表达水平，尽管与NPT1野生型相比，NPT1 I269T变体增加了尿酸转运。结合之前的报道，I269T变异不诱导改变，但增加了蛋白脂质体系统中尿酸盐运输的vmax，我们的研究结果表明，I269T变异增加了NPT1介导的尿酸盐输出，而不增加膜上NPT1的表达水平。因此，就转运体的交替通路模型而言，NPT1常见的错义变体I269T可能比NPT1野生型有更快的构象变化，并增加人类肾尿酸输出。
Human sodium-dependent phosphate cotransporter type 1 (NPT1/SLC17A1) is one of the urate transporters in the kidney. Our recent study revealed that a common missense variant, I269T (rs1165196), ofNPT1decreases the risk of renal underexcretion gout. Moreover, we demonstrated that human NPT1 is localized to the apical membrane of the renal proximal tubule, and that I269T is the gain-of-function variant which increases the NPT1-mediated urate export. However, the mechanism by which I269T variant increases the urate export remains to be clarified. Thus, we performed immunostaining and functional analysis of human NPT1 using theXenopusoocyte expression system. For comparison of human NPT1 expression levels of oocyte membrane between 269I (wild type) and 269T (variant), immunostaining was performed with anti-human NPT1 antibodies. As a result, we showed that NPT1 I269T variant did not change the human NPT1 membrane expression levels, although NPT1 I269T variant increased the urate transport compared with NPT1 wild type. Combined with the previous report that I269T variant did not induceKmchanges but increased theVmaxof urate transport in a proteoliposome system, our findings suggest that I269T variant increases NPT1-mediated urate export without increase of NPT1 expression levels on the membrane. Thus, I269T, a common missense variant of NPT1, might have faster conformation changes than NPT1 wild type in terms of the alternating-access model of transporters, and increases renal urate export in humans.