WNK3 modulates of Cl- transport in and out of cells:: Implications for control of cell volume and neuronal excitability
WNK3 modulates of Cl- transport in and out of cells:: Implications for control of cell volume and neuronal excitability
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DOI：
10.1073/pnas.0508307102
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发表时间：
2005-11-15
影响因子：
11.1
通讯作者：
Lifton, RP
中科院分区：
文献类型：
--
作者：
Kahle, KT;Rinehart, J;Lifton, RP
氯离子进出细胞的调节在维持GABA反应神经元的细胞内容积和兴奋性方面起着关键作用。这些看似不同的过程的分子决定因素是相关的离子共转运蛋白：Cl-内流由Na-K-2Cl共转运蛋白NKCC 1介导，Cl-外流通过K-Cl共转运蛋白KCC 1或KCC 2介导。已经提出了一种Cl-/体积敏感性激酶，通过改变转运蛋白的磷酸化来协调调节这些活动;磷酸化激活NKCC 1，同时抑制KCC，去磷酸化具有相反的作用。我们发现，WNK 3，丝氨酸-苏氨酸激酶的WNK家族的成员，共定位与NKCC 1和KCC 1/2在不同的Cl-转运上皮细胞和表达离子型GABA（A）受体的神经元在海马，小脑，大脑皮层和网状激活系统。通过在非洲爪蟾卵母细胞中的表达研究，我们发现激酶活性WNK 3通过NKCC 1增加Cl-流入，并且它通过KCC 1和KCC 2抑制Cl-退出;激酶失活WNK 3具有相反的作用。WNK 3的作用是通过改变其下游靶点的磷酸化和表面表达来实现的，并绕过了激活这些转运蛋白所需的张力改变的正常要求。总之，这些数据表明，WNK 3可以通过对进入和退出途径的相反作用来调节细胞内Cl-的水平。他们认为，WNK 3是Cl-/体积感应机制的一部分，在渗透胁迫和GABA神经传递的动态调节过程中维持细胞体积是必要的。
The regulation of Cl- transport into and out of cells plays a critical role in the maintenance of intracellular volume and the excitability of GABA responsive neurons. The molecular determinants of these seemingly diverse processes are related ion cotransporters: Cl-influx is mediated by the Na-K-2Cl cotransporter NKCC1 and Cl-efflux via K-Cl cotransporters, KCC1 or KCC2. A Cl-/volume-sensitive kinase has been proposed to coordinately regulate these activities via altered phosphorylation of the transporters; phosphorylation activates NKCC1 while inhibiting KCCs, and dephosphorylation has the opposite effects. We show that WNK3, a member of the WNK family of serine-threonine kinases, colocalizes with NKCC1 and KCC1/2 in diverse Cl--transporting epithelia and in neurons expressing ionotropic GABA(A) receptors in the hippocampus, cerebellum, cerebral cortex, and reticular activating system. By expression studies in Xenopus oocytes, we show that kinase-active WNK3 increases Cl- influx via NKCC1, and that it inhibits Cl- exit through KCC1 and KCC2; kinase-inactive WNK3 has the opposite effects. WNK3's effects are imparted via altered phosphorylation and surface expression of its downstream targets and bypass the normal requirement of altered tonicity for activation of these transporters. Together, these data indicate that WNK3 can modulate the level of intracellular Cl- via opposing actions on entry and exit pathways. They suggest that WNK3 is part of the Cl-/volume-sensing mechanism necessary for the maintenance of cell volume during osmotic stress and the dynamic modulation of GABA neurotransmission.