Aquaporin-4 in the central nervous system: Cellular and subcellular distribution and coexpression with Kir4.1
Aquaporin-4 in the central nervous system: Cellular and subcellular distribution and coexpression with Kir4.1
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DOI：
10.1016/j.neuroscience.2004.08.053
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发表时间：
2004-01-01
期刊：
影响因子：
3.3
通讯作者：
Ottersen, OP
中科院分区：
文献类型：
--
作者：
Nagelhus, EA;Mathiisen, TM;Ottersen, OP
水通道蛋白-4（AQP 4）是中枢神经系统神经元中的主要水通道。它主要在星形胶质细胞中表达，但也发生在室管膜细胞和内皮细胞中。AQP 4表达的一个显著特征是其在脑星形胶质细胞和视网膜Muller细胞中的极化分布。因此，免疫金分析显示，AQP 4在与脑微血管或蛛网膜下腔接触的终足膜中富集，在非终足膜中浓度低但显著，包括包裹谷氨酸突触的星形胶质细胞膜。AQP 4的亚细胞区室化模拟钾通道Kir4.1的亚细胞区室化，Kir4.1与K+的空间缓冲有关。我们建议AQP 4与Kir4.1和生电碳酸氢盐转运体NBC协同工作，并且通过AQP 4的水通量有助于细胞外空间的活性依赖性体积变化。这种体积变化是重要的，因为它们影响细胞外溶质浓度和电场，因此影响神经元兴奋性。我们的结论是，AQP 4介导的水通量代表了脑容量和离子稳态的一个组成部分。(C)2004年IBRO。由爱思唯尔有限公司出版。保留所有权利。
Aquaporin-4 (AQP4) is the predominant water channel in the neuropil of the central nervous system. It is expressed primarily in astrocytes, but also occurs in ependymocytes and endothelial cells. A striking feature of AQP4 expression is its polarized distribution in brain astrocytes and retinal Muller cells. Thus, immunogold analyses have revealed an enrichment of AQP4 in endfeet membranes in contact with brain microvessels or subarachnoidal space and a low but significant concentration in non-endfeet membranes, including those astrocyte membranes that ensheath glutamate synapses. The subcellular compartmentation of AQP4 mimics that of the potassium channel Kir4.1, which is implicated in spatial buffering of K+. We propose that AQP4 works in concert with Kir4.1 and the electrogenic bicarbonate transporter NBC and that water flux through AQP4 contributes to the activity dependent volume changes of the extracellular space. Such volume changes are important as they affect the extracellular solute concentrations and electrical fields, and hence neuronal excitability. We conclude that AQP4-mediated water flux represents an integral element of brain volume and ion homeostasis. (C) 2004 IBRO. Published by Elsevier Ltd. All rights reserved.