Functional characterization of pendrin in a polarized cell system - Evidence for pendrin-mediated apical iodide efflux
Functional characterization of pendrin in a polarized cell system - Evidence for pendrin-mediated apical iodide efflux
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DOI：
10.1074/jbc.m313648200
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发表时间：
2004-03-26
影响因子：
4.8
通讯作者：
Kopp, P
中科院分区：
文献类型：
--
作者：
Gillam, MP;Sidhaye, AR;Kopp, P
彭德氏综合征是一种常染色体隐性遗传病，以感觉神经性耳聋、甲状腺肿大和碘化物组织受损为特征。它是由编码pendin的PDS/ SLC26A4基因突变引起的。在功能上，penddrin是爪蟾卵母细胞和异源哺乳动物细胞中氯离子和碘离子的转运体，也是肾皮质集管β -插层细胞中的氯离子/碱交换剂。Pendred综合征中甲状腺碘组织部分受损提示penddrin可能在甲状腺滤泡细胞顶膜碘转运中起作用，但缺乏实验证据。在表达碘化钠同调体（NIS）、pendrin或NIS和pendrin的极化Madin- Darby犬肾细胞中，使用两院制系统测定了pendrin的碘离子转运特性，该系统允许测量基底室、细胞内室和根尖室的碘离子含量。此外，我们确定了两个自然发生的突变（L676Q和FS306> 309X）的功能后果。在极化的Madin- Darby犬肾细胞中，NIS介导基底外膜的摄取。只有极少量的碘离子在没有管腔的情况下到达根尖室。在表达NIS和penddrin的细胞中，penddrin介导碘离子进入顶室的运输。野生型pendrin在瞬时转染的细胞中也介导碘化物外排。相反，两种penddrin突变体都失去了促进碘化物外排的能力。这些结果提供了证据，证明penddrin介导碘离子负载极化哺乳动物细胞的顶端外排。与在彭德雷德综合征患者中观察到的部分组织缺陷一致，自然发生的彭德雷德基因突变导致碘离子运输受损。
Pendred's syndrome is an autosomal recessive disorder characterized by sensorineural deafness, goiter, and impaired iodide organification. It is caused by mutations in the PDS/ SLC26A4 gene that encodes pendrin. Functionally, pendrin is a transporter of chloride and iodide in Xenopus oocytes and heterologous mammalian cells and a chloride/ base exchanger in beta- intercalated cells of the renal cortical collecting duct. The partially impaired thyroidal iodide organification in Pendred's syndrome suggests a possible role of pendrin in iodide transport at the apical membrane of thyroid follicular cells, but experimental evidence for this concept is lacking. The iodide transport properties of pendrin were determined in polarized Madin- Darby canine kidney cells expressing the sodium iodide symporter ( NIS), pendrin, or NIS and pendrin using a bicameral system- permitting measurement of iodide content in the basal, intracellular, and apical compartments. Moreover, we determined the functional consequences of two naturally occurring mutations ( L676Q and FS306> 309X). In polarized Madin- Darby canine kidney cells, NIS mediates uptake at the basolateral membrane. Only minimal amounts of iodide reach the apical compartment in the absence of pendrin. In cells expressing NIS and pendrin, pendrin mediates transport of iodide into the apical chamber. Wild type pendrin also mediates iodide efflux in transiently transfected cells. In contrast, both pendrin mutants lose the ability to promote iodide efflux. These results provide evidence that pendrin mediates apical iodide efflux from polarized mammalian cells loaded with iodide. Consistent with the partial organification defect observed in patients with Pendred's syndrome, naturally occurring mutations of pendrin lead to impaired transport of iodide.