Fisk Lilia, Nalivaeva Natalia N, Turner Anthony J
Institute of Molecular and Cellular Biology, Faculty of Biological Sciences, Mount Preston Street, University of Leeds, Leeds LS2 9JT, United Kingdom.
Exp Biol Med (Maywood). 2006 Jun;231(6):1048-53.
In recent years endothelin-converting enzyme (ECE-1) has been suggested to play an important role in amyloid-beta peptide metabolism as one of the amyloid-degrading enzymes. In this connection, the analysis of the levels of expression and distribution of ECE-1 in the brain under normal and pathologic conditions could be important in neurodegeneration and pathogenesis of Alzheimer disease. In our previous studies, we have demonstrated that expression of ECE-1 was significantly reduced in the cortex of adult rats after 15 mins of global ischemia. It was also significantly reduced in the striatum of rats subjected to prenatal hypoxia. In the present study, we analyzed effects of hypoxia and oxidative stress on ECE-1 in human neuroblastoma NB7 cells and effects of the cholinergic agonist carbachol and the phorbol ester, phorbol 12-myristate 13-acetate (PMA). We have found that chronic (24 hrs) hypoxia and oxidative stress resulted in 30% and 20% decrease in expression of ECE-1 at the protein level, respectively, although at the level of ECE-1 mRNA there were no statistically significant changes. Serum withdrawal from the incubation medium as well as addition of carbachol or PMA for 24 hrs also led to a significant reduction of the levels of ECE-1 protein in NB7 cells. Further study of the downstream signaling cascades involved in downregulation of ECE expression in NB7 cells and primary neuronal cells might provide us with new insights into possible therapeutic strategies for prevention or treatment of Alzheimer disease in elderly patients and those who suffer from stroke or cerebrovascular disorders.
近年来，内皮素转化酶（ECE - 1）作为淀粉样蛋白降解酶之一，被认为在β淀粉样肽代谢中发挥重要作用。就此而言，分析正常和病理条件下大脑中ECE - 1的表达水平和分布，对于神经退行性变和阿尔茨海默病的发病机制可能具有重要意义。在我们之前的研究中，我们已经证明，成年大鼠全脑缺血15分钟后，其皮质中ECE - 1的表达显著降低。在产前缺氧的大鼠纹状体中，ECE - 1的表达也显著降低。在本研究中，我们分析了缺氧和氧化应激对人神经母细胞瘤NB7细胞中ECE - 1的影响，以及胆碱能激动剂卡巴胆碱和佛波酯（佛波醇12 - 肉豆蔻酸酯13 - 乙酸酯，PMA）的影响。我们发现，慢性（24小时）缺氧和氧化应激分别导致ECE - 1蛋白水平下降30%和20%，尽管在ECE - 1 mRNA水平上没有统计学显著变化。从孵育培养基中撤出血清以及添加卡巴胆碱或PMA 24小时也导致NB7细胞中ECE - 1蛋白水平显著降低。进一步研究NB7细胞和原代神经元细胞中ECE表达下调所涉及的下游信号级联反应，可能会为我们提供新的见解，以制定预防或治疗老年患者以及中风或脑血管疾病患者阿尔茨海默病的可能治疗策略。
