NMDA receptor-mediated Ca(2+) influx triggers nucleocytoplasmic translocation of diacylglycerol kinase ζ under oxygen-glucose deprivation conditions, an in vitro model of ischemia, in rat hippocampal slices
NMDA receptor-mediated Ca(2+) influx triggers nucleocytoplasmic translocation of diacylglycerol kinase ζ under oxygen-glucose deprivation conditions, an in vitro model of ischemia, in rat hippocampal slices
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NMDA 受体介导的 Ca(2+) 内流在缺氧-葡萄糖条件下（体外缺血模型）大鼠海马切片中触发二酰甘油激酶 z 的核质转位
DOI：
10.1007/s00418-011-0907-y
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发表时间：
2012
期刊：
影响因子：
--
通讯作者：
Goto K.
中科院分区：
文献类型：
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作者：
Suzuki Y;Yamazaki Y;Hozumi Y;Okada M;Tanaka T;Iseki K;Ohta N;Aoyagi M;Fujii S;Goto K.
甘油二酯激酶（DGK）通过调节脂质信使甘油二酯的水平在病理生理细胞反应中起关键作用。在DGK同工酶中，DGK β定位于各种细胞如神经元的细胞核。我们以前报道过，短暂性前脑缺血20分钟后，海马CA 1区锥体神经元中的DGK β从细胞核易位到细胞质。在这项研究中，我们研究了潜在的机制，DGK β易位海马脑片暴露于氧-葡萄糖剥夺（OGD）模拟缺血模型的大脑。缺氧20 min后，DG κ B免疫阳性反应逐渐由胞核向胞浆转移，复氧后，DG κ B免疫阳性反应在胞核消失。有趣的是，DGK β在OGD 10分钟时在细胞核中检测到，而随后的60分钟复氧诱导DGK β完全胞质易位。形态计量学分析显示，DGK-β胞质易位与核收缩相关，表明神经元变性的早期过程。在OGD条件下的易位被NMDA受体（NMDAR）抑制剂阻断，并通过激活NMDAR来诱导。螯合的细胞外Ca 2+阻断OGD条件下的易位。这些结果表明，DGK β胞质易位是由NMDAR的激活引发的，随后细胞外Ca 2+内流。此外，在OGD条件下抑制PKC活性导致约三分之一的神经元中DGK β的核滞留，表明PKC活性部分调节DGK β胞质易位。这些发现为进一步研究谷氨酸对海马神经元的兴奋毒性机制提供了线索。
Diacylglycerol kinase (DGK) plays a key role in pathophysiological cellular responses by regulating the levels of a lipid messenger diacylglycerol. Of DGK isozymes, DGKζ localizes to the nucleus in various cells such as neurons. We previously reported that DGKζ translocates from the nucleus to the cytoplasm in hippocampal CA1 pyramidal neurons after 20 min of transient forebrain ischemia. In this study, we examined the underlying mechanism of DGKζ translocation using hippocampal slices exposed to oxygen-glucose deprivation (OGD) to simulate an ischemic model of the brain. DGKζ-immunoreactivity gradually changed from the nucleus to the cytoplasm in CA1 pyramidal neurons after 20 min of OGD and was never detected in the nucleus after reoxygenation. Intriguingly, DGKζ was detected in the nucleus at 10 min OGD whereas the following 60 min reoxygenation induced complete cytoplasmic translocation of DGKζ. Morphometric analysis revealed that DGKζ cytoplasmic translocation correlated with nuclear shrinkage indicative of an early process of neuronal degeneration. The translocation under OGD conditions was blocked by NMDA receptor (NMDAR) inhibitor, and was induced by activation of NMDAR. Chelation of the extracellular Ca2+blocked the translocation under OGD conditions. These results show that DGKζ cytoplasmic translocation is triggered by activation of NMDAR with subsequent extracellular Ca2+influx. Furthermore, inhibition of PKC activity under OGD conditions led to nuclear retention of DGKζ in about one-third of the neurons, suggesting that PKC activity partially regulates DGKζ cytoplasmic translocation. These findings provide clues to guide further investigation of glutamate excitotoxicity mechanisms in hippocampal neurons.