ClC-5 chloride channel alters expression of the epithelial sodium channel (ENaC).
ClC-5 chloride channel alters expression of the epithelial sodium channel (ENaC).
复制标题
ClC-5 氯通道改变上皮钠通道 (ENaC) 的表达。
DOI：
10.1007/s00232-004-0717-4
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发表时间：
2004
期刊：
影响因子：
--
通讯作者：
Wills,NK
中科院分区：
文献类型：
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作者：
Mo,L;Wills,NK
ClC-5氯离子通道和上皮钠离子通道（ENaC）存在于许多细胞类型中，包括气道和视网膜上皮。由于已知ENaC活性受氯化物转运的影响，我们将编码ENaC和ClC-5的crna共同注射到xenopusoocytes中，以研究这些蛋白的异种共表达是否会影响通道电流。与ENaC共表达对ClC-5电流没有明显影响，而与单独表达ENaC的对照卵母细胞相比，阿米洛利敏感的ENaC电流明显降低。ENaC与编码ClC-5非导电片段的cRNA序列共表达表明，位置347和647之间的氨基酸序列区域足以抑制ENaC电流。ENaC与另一种转运蛋白二羧酸钠共转运蛋白（NaDC-1）的共表达不影响ENaC电流。为了检验ClC-5的抑制作用是否对ENaC具有特异性，我们还将ClC-5与CFTR共表达。CFTR电流也被与ClC-5共表达抑制，而ClC-5电流不受影响。生物素化卵母细胞表面膜的Western blot分析显示，ClC-5与ENaC、CFTR或NaDC-1的共表达降低了这些蛋白在表面膜上的丰度。我们得出的结论是，过表达的ClC-5，特别是氨基酸347-647，可以改变ENaC和其他离子转运蛋白的正常翻译或运输，其机制与ClC-5的氯离子电导无关。
ClC-5 chloride channels and epithelial sodium channels (ENaC) are present in many cell types including airway and retinal epithelia. Since ENaC activity is known to be affected by chloride transport, we co-injectedXenopusoocytes with cRNAs encoding ENaC and ClC-5 to investigate whether channel currents are impacted by heterologous co-expression of these proteins. ClC-5 currents were not detectably affected by co-expression with ENaC, whereas amiloride-sensitive ENaC currents were significantly lower compared to control oocytes expressing ENaC alone. Co-expression of ENaC with cRNA sequences encoding non-conducting fragments of ClC-5 revealed that the amino acid sequence region between positions 347 and 647 was sufficient for inhibition of ENaC currents. Co-expression of ENaC and another transport protein, the sodium dicarboxylate co-transporter (NaDC-1), did not affect ENaC currents. To test whether the inhibitory effects of ClC-5 were specific for ENaC, ClC-5 was also co-expressed with CFTR. CFTR currents were also inhibited by co-expression with ClC-5, whereas ClC-5 currents were unaffected. Western blot analysis of biotinylated oocyte surface membranes revealed that the co-expression of ClC-5 with ENaC, CFTR, or NaDC-1 decreased the abundance of these proteins at the surface membrane. We conclude that overexpression of ClC-5, specifically amino acids 347–647, can alter the normal translation or trafficking of ENaC and other ion transport proteins by a mechanism that is independent of the chloride conductance of ClC-5.