PDZ-domain interactions and apical expression of type IIa Na/Pi cotransporters
PDZ-domain interactions and apical expression of type IIa Na/Pi cotransporters
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DOI：
10.1073/pnas.182412699
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发表时间：
2002-09-03
影响因子：
11.1
通讯作者：
Murer, H
中科院分区：
文献类型：
--
作者：
Hernando, N;Déliot, N;Murer, H
IIa型Na/P-i共转运蛋白表达于肾近端刷状缘，是无机磷酸盐（P-i）重吸收的主要决定因素。它们的羧基末端尾包含顶端表达的信息，并通过其三个末端氨基酸与几个含有PSD9.5/DgIA/ZO-1样结构域（PDZ）的蛋白相互作用。其中两种蛋白质，NaPi-Cap 1和Na/H交换调节因子1（NHERF 1），与近端刷状缘中的协同转运蛋白共定位。我们使用负鼠肾细胞来测试PDZ相互作用对协同转运蛋白顶端表达的潜在作用的假设。我们发现负鼠肾细胞含有NaPi-Cap 1和NHERF 1 mRNA。对于NHERF 1，可以记录蛋白质的顶端位置;该位置可能反映了通过MERM结合结构域与细胞骨架的相互作用。PDZ结构域的过表达与协同转运蛋白（PDZ-1/NHERF 1和PDZ-3/NaPi-Cap 1）的相互作用具有显性负效应，干扰顶端的协同转运蛋白的表达，而不影响肌动蛋白细胞骨架或Na/K-ATP酶的基底侧表达。这些数据表明参与PDZ相互作用的顶端表达IIa型共转运蛋白。
Type IIa Na/P-i cotransporters are expressed in renal proximal brush border and are the major determinants of inorganic phosphate (P-i) reabsorption. Their carboxyl-terminal tail contains information for apical expression, and interacts by means of its three terminal amino acids with several PSD9.5/DgIA/ZO-1-like domain (PDZ)containing proteins. Two of these proteins, NaPi-Cap1 and Na/H exchanger-regulatory factor 1 (NHERF1), colocalize with the cotransporter in the proximal brush border. We used opossum kidney cells to test the hypothesis of a potential role of PDZ-interactions on the apical expression of the cotransporter. We found that opossum kidney cells contain NaPi-Cap1 and NHERF1 mRNAs. For NHERF1, an apical location of the protein could be documented; this location probably reflects interaction with the cytoskeleton by means of the MERM-binding domain. Overexpression of PDZ domains involved in interaction with the cotransporter (PDZ-1/NHERF1 and PDZ-3/NaPi-Cap1) had a dominant-negative effect, disturbing the apical expression of the cotransporter without affecting the actin cytoskeleton or the basolateral expression of Na/K-ATPase. These data suggest an involvement of PDZ-interactions on the apical expression of type IIa cotransporters.