A critical role for the potassium-dependent sodium-calcium exchanger NCKX2 in protection against focal ischemic brain damage
A critical role for the potassium-dependent sodium-calcium exchanger NCKX2 in protection against focal ischemic brain damage
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DOI：
10.1523/jneurosci.4912-07.2008
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发表时间：
2008-02-27
影响因子：
5.3
通讯作者：
Annunziato, Lucio
中科院分区：
文献类型：
--
作者：
Cuomo, Ornella;Gala, Rosaria;Annunziato, Lucio
阳离子/钙离子膜交换器超家族包括两个分支：K+非依赖性Na+-Ca~(2+)交换器(NCXs)和K~+依赖性Na~+-Ca~(2+)交换器(NCKXs)，它们广泛表达于哺乳动物。NCKX2是NCKX成员中主要的神经元表达亚型。尽管NCKX2在维持中枢神经系统内Na+、Ca~(2+)和K~+动态平衡方面具有重要作用，但它在以离子浓度变化为特征的脑缺血中的作用尚未被研究。本研究旨在探讨NCKX2在永久性大脑中动脉闭塞(PMCAO)和短暂性大脑中动脉闭塞(TMCAO)缺血性脑损伤中的作用。此外，为了评估nck x2消融对神经元存活的影响，我们对nck x2-/-原代皮层神经元进行了氧糖剥夺加复氧。观察大鼠大脑中动脉闭塞后不同时间点缺血区及周围缺血区NCKX2基因和蛋白的表达。在缺血中心区和梗死灶周围，NCKX2基因和蛋白表达下调。此外，NCKX2被反义寡核苷酸敲除，NCKX2被基因破坏敲除，显著增加了脑梗塞体积。因此，与nck x2+/+神经元相比，nck x2-/-原代皮质神经元在低氧条件下表现出更高的脆弱性和更大的[Ca~(2+)](I)升高。此外，正向和反向工作模式下的NCKX电流在nCKX2-/-神经元中均显著低于nCKX2+/+细胞。综上所述，这些结果表明NCKX2参与了脑缺血，它可能是研究脑缺血分子机制的一个新的潜在靶点。
The superfamily of cation/Ca2+ plasma-membrane exchangers contains two branches, the K+- independent Na+-Ca2+ exchangers ( NCXs) and the K+- dependent Na+-Ca2+ exchangers ( NCKXs), widely expressed in mammals. NCKX2 is the major neuronally expressed isoform among NCKX members. Despite its importance in maintaining Na+, Ca2+, and K+ homeostasis in the CNS, the role of NCKX2 during cerebral ischemia, a condition characterized by an alteration of ionic concentrations, has not yet been investigated. The present study examines NCKX2 role in the development of ischemic brain damage in permanent middle cerebral artery occlusion ( pMCAO) and transient middle cerebral artery occlusion. Furthermore, to evaluate the effect of nckx2 ablation on neuronal survival, nckx2-/- primary cortical neurons were subjected to oxygen glucose deprivation plus reoxygenation. NCKX2 mRNA and protein expression was evaluated in the ischemic core and surrounding ipsilesional areas, at different time points after pMCAO in rats. In ischemic core and in periinfarctual area, NCKX2 mRNA and protein expression were downregulated. In addition, NCKX2 knock-down by antisense oligodeoxynucleotide and NCKX2 knock-out by genetic disruption dramatically increased infarct volume. Accordingly, nckx2-/- primary cortical neurons displayed a higher vulnerability and a greater [ Ca2+](i) increase under hypoxic conditions, compared with nckx2+/+ neurons. In addition, NCKX currents both in the forward and reverse mode of operation were significantly reduced in nckx2-/- neurons compared with nckx2+/+ cells. Overall, these results indicate that NCKX2 is involved in brain ischemia, and it may represent a new potential target to be investigated in the study of the molecular mechanisms involved in cerebral ischemia.