Analysis of opossum kidney NaPi-IIc sodium-dependent phosphate transporter to understand Pi handling in human kidney.
Analysis of opossum kidney NaPi-IIc sodium-dependent phosphate transporter to understand Pi handling in human kidney.
复制标题
分析负鼠肾 NaPi-IIc 钠依赖性磷酸盐转运蛋白，以了解人体肾脏中的 Pi 处理。
DOI：
10.1007/s10157-018-1653-4
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发表时间：
2019
期刊：
影响因子：
2.3
通讯作者：
Miyamoto KI.
中科院分区：
文献类型：
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作者：
Fujii T;Shiozaki Y;Segawa H;Nishiguchi S;Hanazaki A;Noguchi M;Kirino R;Sasaki S;Tanifuji K;Koike M;Yokoyama M;Arima Y;Kaneko I;Tatsumi S;Ito M;Miyamoto KI.
背景Na+依赖性无机磷酸盐（Pi）转运体在人肾脏中的作用尚不完全清楚。遗传性低磷血症佝偻病伴高钙尿症（HHRH）是由IIc Na+依赖性Pi转运蛋白（NPT 2c/Npt 2c/NaPi-IIc）基因的功能缺失突变引起的。另一种Na+依赖性II型转运蛋白（NPT 2A/Npt 2a/NaPi-IIa）对人体肾Pi重吸收也很重要。在小鼠中，Npt 2c缺失不会导致低磷酸盐血症和佝偻病，因为Npt 2a补偿了受损的Pi重吸收。为了阐明小鼠和人类之间的差异，我们研究了负鼠肾（OK）细胞中NaPi-IIa和NaPi-IIc功能之间的关系。我们使用oNaPi-IIc小干扰（si）RNA和调查的作用，NaPi-IIc在Pi运输OK cells.ResultsWe克隆负鼠肾NaPi-IIc cDNA编码622个氨基酸的蛋白质（变体1），并检查其pH值和钠的依赖性。抗体特异性地与75-kDa和150-kDa蛋白条带反应，并且NaPi-IIc的siRNA显著抑制OK细胞中的内源性oNaPi-IIc。用siRNA处理显著抑制NaPi-4（NaPi-IIa）蛋白和mRNA的表达。oNaPi-IIc siRNA也能抑制OK细胞Na+/H+交换调节因子1的表达。结论NaPi-IIc对OK细胞NaPi-IIa（NaPi-4）蛋白的表达具有重要作用。抑制Npt 2c可能下调HHRH患者的Npt 2a功能。
BackgroundThe role of Na+-dependent inorganic phosphate (Pi) transporters in the human kidney is not fully clarified. Hereditary hypophosphatemic rickets with hypercalciuria (HHRH) is caused by loss-of-function mutations in the IIc Na+-dependent Pi transporter (NPT2c/Npt2c/NaPi-IIc) gene. Another Na+-dependent type II transporter, (NPT2A/Npt2a/NaPi-IIa), is also important for renal Pi reabsorption in humans. In mice, Npt2c deletion does not lead to hypophosphatemia and rickets because Npt2a compensates for the impaired Pi reabsorption. To clarify the differences between mouse and human, we investigated the relation between NaPi-IIa and NaPi-IIc functions in opossum kidney (OK) cells.MethodsWe cloned NaPi-IIc from OK cells and created opossum NaPi-IIc (oNaPi-IIc) antibodies. We used oNaPi-IIc small interference (si)RNA and investigated the role of NaPi-IIc in Pi transport in OK cells.ResultsWe cloned opossum kidney NaPi-IIc cDNAs encoding 622 amino acid proteins (variant1) and examined their pH- and sodium-dependency. The antibodies reacted specifically with 75-kDa and 150-kDa protein bands, and the siRNA of NaPi-IIc markedly suppressed endogenous oNaPi-IIc in OK cells. Treatment with siRNA significantly suppressed the expression of NaPi-4 (NaPi-IIa) protein and mRNA. oNaPi-IIc siRNA also suppressed Na+/H+exchanger regulatory factor 1 expression in OK cells.ConclusionThese findings suggest that NaPi-IIc is important for the expression of NaPi-IIa (NaPi-4) protein in OK cells. Suppression of Npt2c may downregulate Npt2a function in HHRH patients.