Tonicity-responsive enhancer binding protein is an essential regulator of aquaporin-2 expression in renal collecting duct principal cells
Tonicity-responsive enhancer binding protein is an essential regulator of aquaporin-2 expression in renal collecting duct principal cells
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DOI：
10.1681/asn.2005121317
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发表时间：
2006-06-01
影响因子：
13.6
通讯作者：
Martin, Pierre-Yves
中科院分区：
文献类型：
--
作者：
Hasler, Udo;Jeon, Un Sil;Martin, Pierre-Yves
张力反应增强子结合蛋白（TonEBP）通过刺激特定基因的转录，在保护肾细胞免受高渗应激中起关键作用。在高渗条件下，TonEBP活性通过增加核转位、反式激活和丰度而增强。以往的研究表明，高渗对永生化小鼠集合管主细胞（mp-kCCD（c14））中加压素诱导的水通道蛋白-2（AQP 2）表达具有双重的时间依赖性影响。高渗刺激3 h后AQP 2丰度降低，高渗刺激24 h后AQP 2丰度升高。本研究通过对mpkCCD（c14）细胞进行3或24 It的高渗激发来研究TonEBP在这些事件中可能发挥的作用。过度扭转刺激增加了TonEBP mRNA和蛋白质含量，并增强了TonEBP活性，如TonEBP依赖性荧光素酶活性增加和TonEBP靶向的几个基因的mRNA表达增加所示。无论加压素的存在或不存在，TonEBP的小干扰RNA或抑制形式的TonEBP转染细胞中的TonEBP活性降低，强烈降低AQP 2 mRNA和蛋白质含量在等渗条件下，并钝化AQP 2丰度的增加，诱导高渗24小时后的挑战。相反，TonEBP活性降低并没有显着改变AQP 2 mRNA的表达减少，诱导3小时的高渗挑战。位于AQP 2转录起始位点上游489 bp的TonE增强子元件的突变废除了表达AQP 2启动子-荧光素酶质粒构建体的细胞中高渗诱导的荧光素酶活性增加，表明TonEBP至少部分通过直接作用于AQP 2启动子来影响AQP 2转录活性。这些结果表明，在集合管主细胞，TonEBP通过增强AQP 2基因转录调节AQP 2的表达发挥了核心作用。
Tonicity-responsive enhancer binding protein (TonEBP) plays a key role in protecting renal cells from hypertonic stress by stimulating transcription of specific genes. Under hypertonic conditions, TonEBP activity is enhanced via increased nuclear translocation, transactivation, and abundance. It was reported previously that hypertonicity exerted a dual, time-dependent effect on vasopressin-inducible aquaporin-2 (AQP2) expression in immortalized mouse collecting duct principal cells (mp-kCCD(c14)) Whereas AQP2 abundance decreased after 3 h of hyperosmotic challenge, it increased after 24 It of hypertonic challenge. This study investigated the role that TonEBP may play in these events by subjecting mpkCCD(c14) cells to 3 or 24 It of hypertonic challenge. Hypertortic challenge increased TonEBP mRNA and protein content and enhanced TonEBP activity as illustrated by both increased TonEBP-dependent lucif erase activity and mRNA expression of several genes that are targeted by TonEBP. Irrespective of the absence or presence of vasopressin, decreased TonEBP activity in cells that were transfected with either TonEBP small interfering RNA or an inhibitory form of TonEBP strongly reduced AQP2 mRNA and protein content under iso-osmotic conditions and blunted the increase of AQP2 abundance that was induced after 24h of hypertonic challenge. Conversely, decreased TonEBP activity did not significantly alter reduced expression of AQP2 mRNA that was induced by 3 h of hypertonic challenge. Mutation of a TonE enhancer element located 489 bp upstream of the AQP2 transcriptional start site abolished the hypertonicity-induced increase of luciferase activity in cells that expressed AQP2 promoter-lucif erase plasmid constructs, indicating that TonEBP influences AQP2 transcriptional activity at least partially by acting directly on the AQP2 promoter. These findings demonstrate that in collecting duct principal cells, TonEBP plays a central role in regulating AQP2 expression by enhancing AQP2 gene transcription.