Shekarabi M, Bourbonnière M, Dagenais A, Nalbantoglu J
Department of Neurology and Neurosurgery, McGill Center for Studies in Aging, McGill University, Montreal, Quebec, Canada.
J Neurochem. 1997 Mar;68(3):970-8. doi: 10.1046/j.1471-4159.1997.68030970.x.
Early expression of amyloid precursor protein (APP) during development of the nervous system suggests that this protein may play an important role first in axogenesis and later in synaptogenesis. To study regulation of APP mRNA expression in neuronal cells, NG108-15 neuroblastoma x glioma cells were induced to differentiate in the presence of dibutyryl cyclic AMP. Steady-state levels of APP mRNA and APP isoforms increased gradually, concomitantly with the appearance of differentiated phenotype. Northern blot analysis showed a three-fold increase in APP expression at day 6 of dibutyryl cyclic AMP treatment. Nuclear run-on assays and transient transfections performed using APP promoter/reporter constructs confirmed a twofold increase in the rate of APP gene transcription. The stability of the mRNA was unchanged, with differentiated and nondifferentiated cells having the same half-life of about 21 h. These results strongly suggest that APP mRNA induction in the differentiated NG108-15 cells is due to an increase in the rate of transcription of the gene.
淀粉样前体蛋白(APP)在神经系统发育过程中的早期表达表明,该蛋白可能首先在轴突发生中起重要作用,随后在突触发生中起重要作用。为了研究神经元细胞中APP mRNA表达的调控,在存在二丁酰环磷酸腺苷的情况下诱导NG108 - 15神经母细胞瘤×胶质瘤细胞分化。APP mRNA和APP亚型的稳态水平逐渐增加,同时出现分化表型。Northern印迹分析显示,在二丁酰环磷酸腺苷处理的第6天,APP表达增加了三倍。使用APP启动子/报告基因构建体进行的核转录分析和瞬时转染证实,APP基因转录速率增加了两倍。mRNA的稳定性未发生变化,分化和未分化细胞的半衰期相同,约为21小时。这些结果有力地表明,分化的NG108 - 15细胞中APP mRNA的诱导是由于该基因转录速率的增加。