U18666A-mediated apoptosis in cultured murine cortical neurons: Role of caspases, calpains and kinases
U18666A-mediated apoptosis in cultured murine cortical neurons: Role of caspases, calpains and kinases
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DOI：
10.1016/j.cellsig.2005.12.006
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发表时间：
2006-10-01
影响因子：
4.8
通讯作者：
Cheung, Nam Sang
中科院分区：
文献类型：
--
作者：
Koh, Chor Hui Vivien;Qi, Robert Z.;Cheung, Nam Sang
研究表明，大脑中的胆固醇失衡可能与神经系统疾病的发展有关，如阿尔茨海默病和C型尼曼-皮克病。以前，我们已经报道，U18666 A，胆固醇转运抑制剂，导致细胞凋亡和细胞内胆固醇积累在原代皮层神经元。在这项研究中，我们研究了U18666 A介导的神经元凋亡的影响，发现长期暴露于U18666 A导致半胱天冬酶和钙蛋白酶的激活和tau蛋白的过度磷酸化。Tau蛋白的过度磷酸化受几种在体外磷酸化Tau蛋白特定位点的激酶的调节。令人惊讶的是，在U18666 A处理的皮质神经元中，细胞周期蛋白依赖性激酶5的激酶活性降低，而其蛋白水平保持不变。糖原合成酶激酶3和丝裂原活化蛋白激酶的量被发现减少其磷酸化状态的蛋白质印迹分析。使用微阵列分析进一步研究基因转录。编码激酶和磷酸酶的基因在U18666 A处理后差异表达，其中大部分表达上调，一些表达下调。半胱氨酸蛋白酶的激活和胆固醇积累与tau蛋白病可能提供线索的细胞机制的抑制胆固醇转运介导的细胞死亡的神经退行性疾病。(c)2005年爱思唯尔公司All rights reserved.
Studies have suggested that cholesterol imbalance in the brain might be related to the development of neurological disorders such as Alzheimer's disease and Niemann-Pick disease type C. Previously, we have reported that U18666A, a cholesterol transport-inhibiting agent, leads to apoptosis and intracellular cholesterol accumulation in primary cortical neurons. In this study, we examined the effects of U18666A-mediated neuronal apoptosis, and found that chronic exposure to U18666A led to the activation of caspases and calpains and hyperphosphorylation of tau. Tau hyperphosphorylation is regulated by several kinases that phosphorylate specific sites of tau in vitro. Surprisingly, the kinase activity of cyclin-dependent kinase 5 decreased in U18666A-treated cortical neurons whereas its protein level remained unchanged. The amount of glycogen synthase kinase 3 and mitogen-activated protein kinases were found to decrease in their phosphorylated states by Western blot analysis. Gene transcription was further studied using microarray analysis. Genes encoding for kinases and phosphatases were differentially expressed with most up-regulated and some down-regulated in expression upon U18666A treatment. The activation of cysteine proteases and cholesterol accumulation with tauopathies may provide clues to the cellular mechanism of the inhibition of cholesterol transport-mediated cell death in neurodegenerative diseases. (c) 2005 Elsevier Inc. All rights reserved.