Graduate School of Life Science, University of Hyogo, 3-2-1 Kouto, Kamigori, Hyogo 678-1297, Japan.
Neurosci Lett. 2010 Mar 26;472(3):188-93. doi: 10.1016/j.neulet.2010.01.081. Epub 2010 Feb 4.
Phospholipase C-delta1 (PLCdelta1) is the most fundamental form of the eukaryotic PLC and thought to play important roles in the regulation of cells. We previously reported that PLCdelta1 shuttles between the cytoplasm and nucleus, and an influx of Ca2+ triggers the nuclear import of PLCdelta1 via Ca2+-dependent interaction with importin beta1, although the physiological meaning of this is unclear. Here we have examined the distribution of PLCdelta1 using primary cultures of rat hippocampal neurons. Treatment of 7DIV neurons with ionomycin or thapsigargin caused the nuclear localization of PLCdelta1 as has been observed in other cell lines. Similar results were obtained with neurons treated with glutamate, suggesting that the nuclear localization of PLCdelta1 plays some roles in excitotoxicity associated with ischemic stress. Generally, cells undergoing ischemic or hypoxic cell death show nuclear shrinkage. We confirmed that a massive influx of Ca2+ caused similar results. Furthermore, overexpression of GFP-PLCdelta1 facilitated ionomycin-induced nuclear shrinkage in embryonic fibroblasts derived from PLCdelta1 gene-knockout mice (PLCdelta1KO-MEF). By contrast, an E341A mutant that cannot bind with importin beta1 and be imported into the nucleus by ionomycin and also lacks enzymatic activity did not cause nuclear shrinkage in PLCdelta1KO-MEF. Nuclear translocation and the PLC activity of PLCdelta1, therefore, may regulate the nuclear shape by controlling the nuclear scaffold during stress-induced cell death caused by high levels of Ca2+.
磷酯酶 C-δ1（PLCδ1）是真核生物 PLC 中最基本的形式，被认为在细胞调节中发挥重要作用。我们之前曾报道 PLCδ1 在细胞质和细胞核之间穿梭，钙离子流入通过与 importinβ1 的钙离子依赖性相互作用触发 PLCδ1 的核内输入，尽管其生理意义尚不清楚。在这里，我们使用原代培养的大鼠海马神经元检查了 PLCδ1 的分布。用离子霉素或 thapsigargin 处理 7DIV 神经元会导致 PLCδ1 的核定位，这与在其他细胞系中观察到的情况相同。用谷氨酸处理的神经元也得到了类似的结果，这表明 PLCδ1 的核定位在与缺血应激相关的兴奋性毒性中发挥一些作用。一般来说，经历缺血或缺氧细胞死亡的细胞显示核收缩。我们证实大量钙离子流入会导致类似的结果。此外，GFP-PLCδ1 的过表达促进了 PLCδ1 基因敲除小鼠（PLCδ1KO-MEF）来源的胚胎成纤维细胞中离子霉素诱导的核收缩。相比之下，不能与 importinβ1 结合并且不能被离子霉素导入核内的 E341A 突变体在 PLCδ1KO-MEF 中不会引起核收缩。因此，PLCδ1 的核易位和 PLC 活性可能通过在由高浓度钙离子引起的应激诱导的细胞死亡过程中控制核支架来调节核形状。
