Rab proteins regulate epithelial sodium channel activity in colonic epithelial HT-29 cells
Rab proteins regulate epithelial sodium channel activity in colonic epithelial HT-29 cells
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DOI：
10.1016/j.bbrc.2005.09.186
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发表时间：
2005-12-02
影响因子：
3.1
通讯作者：
Kaur, S
中科院分区：
文献类型：
--
作者：
Saxena, S;Singh, M;Kaur, S
ENaC，钠选择性阿米洛利敏感上皮通道，介导紧致上皮中的电致钠再吸收，并与人类高血压密切相关。ENaC在质膜上的表达需要以一种明确和高度区隔的方式进行调控的运输、加工和大分子组装。ras相关的Rab gtpase在胞吞过程中调节细胞内运输，调节胞吐和分泌。为了评估这些蛋白在调节酰胺敏感钠通道活性中的作用，我们在HT-29细胞中表达了多种rabb异构体3、5、6和Rab27a。Rab3和Rab27a抑制ENaC电流，而其他Rab亚型的表达对酰胺敏感电流没有统计学意义上的显著影响。免疫沉淀实验提示Rab3和Rab27a与上皮钠通道存在蛋白-蛋白相互作用。生物素化研究表明ENaC功能的调节是由于通道蛋白的顶端表达减少。研究还表明，Rabs似乎不影响细胞ENaC的稳态水平。或者，引入同种异构体特异性小抑制RNA （SiRNA）逆转了rab依赖的对阿米洛利敏感电流的抑制。这些观察结果表明，多种Rab蛋白参与ENaC通过胞外作用、内质网再循环到质膜或降解等细胞内途径的运输，从而成为人类高血压的潜在靶点。(c) 2005爱思唯尔公司版权所有。
ENaC, the sodium-selective amiloride-sensitive epithelial channel, mediates electrogenic sodium re-absorption in tight epithelia and is deeply associated with human hypertension. The ENaC expression at plasma membrane requires the regulated transport, processing, and macromolecular assembly in a defined and highly compartmentalized manner. Ras-related Rab GTPases regulate intracellular trafficking during endocytosis, regulated exocytosis, and secretion. To evaluate the role of these proteins in regulating amiloride-sensitive sodium channel activity, multiple Rab isoforrns 3, 5, 6, and Rab27a were expressed in HT-29 cells. Rab3 and Rab27a inhibited ENaC currents, while the expression of other Rab isoforms failed to elicit any statistically significant effect on amiloride-sensitive currents. The immunoprecipitation experiments suggest protein-protein interaction of Rab3 and Rab27a with epithelial sodium channel. Biotinylation studies revealed that modulation of ENaC function is due to the reduced apical expression of channel proteins. Study also indicates that Rabs do not appear to affect the steady-state level of total cellular ENaC. Alternatively, introduction of isoform-specific small inhibitory RNA (SiRNA) reversed the Rab-dependent inhibition of amiloride-sensitive currents. These observations point to the involvement of multiple Rab proteins in ENaC transport through intracellular routes like exocytosis, recycling from ER to plasma membrane or degradation and thus serve as potential target for human hypertension. (c) 2005 Elsevier Inc. All rights reserved.