Impaired acidification in early endosomes of CIC-5 deficient proximal tubule
Impaired acidification in early endosomes of CIC-5 deficient proximal tubule
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DOI：
10.1016/j.bbrc.2005.02.060
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发表时间：
2005-04-15
影响因子：
3.1
通讯作者：
Verkman, AS
中科院分区：
文献类型：
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作者：
Hara-Chikuma, M;Wang, YH;Verkman, AS
ClC-5氯通道缺乏导致蛋白尿、高钙尿和肾结石（登特病）。近端小管内体酸化受损是由氯离子电导率降低引起的。然而，卵母细胞中ClC-5的功能分析预测，由于其酸性内部pH值和正电位，内体中的ClC-5氯离子电导率较低。在这里，使用荧光传感器偶联转铁蛋白（早期/循环核内体）或α(2)-巨球蛋白（晚期核内体），在野生型和ClC-5缺陷小鼠的近端小管细胞培养物中测量内体pH和氯化物浓度。转铁蛋白标记内体的初始pH值与7.2相似，在野生型和ClC-5缺陷细胞中分别在15分钟降至6.0和6.5；相应的内体氯化物浓度从16 mM增加到47 mM和36 mM。相反，酸化和氯化物积累在晚期内体或高尔基体中没有受到损害。我们的研究结果为ClC-5通过氯离子分流机制参与近端小管早期内体的酸化提供了直接证据。(c) 2005爱思唯尔公司版权所有。
ClC-5 chloride channel deficiency causes proteinuria, hypercalciuria, and nephrolithiasis (Dent's disease). Impaired endosomal acidification in proximal tubule caused by reduced chloride conductance is a proposed mechanism; however, functional analysis of ClC-5 in oocytes predicts low ClC-5 chloride conductance in endosomes because of their acid interior pH and positive potential. Here, endosomal pH and chloride concentration were measured in proximal tubule cell cultures from wildtype vs. ClC-5 deficient mice using fluorescent sensors coupled to transferrin (early/recycling endosomes) or alpha(2)-macroglobulin (late endosomes). Initial pH in transferrin-labeled endosomes was similar to 7.2, decreasing at 15 min to 6.0 vs. 6.5 in wildtype vs. ClC-5 deficient cells, respectively; corresponding endosomal chloride concentration increased from similar to 16 mM to 47 vs. 36 mM. In contrast, acidification and chloride accumulation were not impaired in late endosomes or Golgi. Our results provide direct evidence for ClC-5 involvement in acidification of early endosomes in proximal tubule by a chloride shunt mechanism. (c) 2005 Elsevier Inc. All rights reserved.