Differential effects of the Swedish mutant amyloid precursor protein on β-amyloid accumulation and secretion in neurons and nonneuronal cells
Differential effects of the Swedish mutant amyloid precursor protein on β-amyloid accumulation and secretion in neurons and nonneuronal cells
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DOI：
10.1074/jbc.272.51.32247
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发表时间：
1997-12-19
影响因子：
4.8
通讯作者：
Lee, VMY
中科院分区：
文献类型：
--
作者：
Forman, MS;Cook, DG;Lee, VMY
淀粉样前体蛋白（APP Delta NL）中瑞典Delta NL突变的表达显著增加了非神经元细胞中A β的产生。细胞系，尽管尚不清楚在APP Delta NL表达后β-淀粉样蛋白（A β）的细胞内水平是否也升高。此外，在神经元中表达APP Delta NL对A β-（1-40）和A β-（1-42）的产生和分泌的影响尚不清楚。为了解决这些问题，我们研究了在人神经元NT 2N细胞、原代大鼠星形胶质细胞和使用重组Semliki Forest病毒表达系统工程化以表达野生型APP或APP Delta NL的中国仓鼠卵巢细胞中细胞内和分泌的A β-（1-40）和A β-（1-42）的产生。在所有测试的细胞中，APP Delta NL的表达导致APP β和含有整个A β序列（C99）的C末端片段显著增加。然而，仅在星形胶质细胞和中国仓鼠卵巢细胞中观察到细胞内和分泌的A β-（1-40）和A β-（1-42）的显著升高。Delta NL突变未导致NT 2N细胞中细胞内或分泌的A β-（1-40）或A β-（1-42）显著增加。由于表达APP Delta NL的NT 2N细胞比表达野生型APP的细胞积累更高水平的C99，我们得出结论，A β产生的限速步骤可能是这些细胞中γ-分泌酶对C99的进一步加工。这些结果表明，瑞典Delta NL突变导致非神经元细胞通过与神经元中野生型APP代谢更常见的途径处理APP。
Expression of the Swedish Delta NL mutation in the beta-amyloid precursor protein (APP Delta NL) dramatically increases A beta generation in nonneuronal cell. lines, although it is unclear whether intracellular levels of beta-amyloid (A beta) are also elevated after APP Delta NL expression. Furthermore, the effects of expressing APP Delta NL in neurons on the production and secretion of A beta-(1-40) and A beta-(1-42) are unknown. To address these issues, we examined the generation of both intracellular and secreted A beta-(1-40) and A beta-(1-42) in human neuronal NT2N cells, in primary rat astrocytes, and in Chinese hamster ovary cells engineered to express wild-type APP or APP Delta NL using a recombinant Semliki Forest virus expression system. Expression of APP Delta NL led to a marked increase in APP beta and the C-terminal fragment containing the entire A beta sequence (C99) in all cells tested. However, a dramatic elevation of intracellular and secreted A beta-(1-40) and A beta-(1-42) was seen only in astrocytes and Chinese hamster ovary cells. The Delta NL mutation did not cause a significant increase in intracellular or secreted A beta-(1-40) or A beta-(1-42) in NT2N cells. Since NT2N cells expressing APP Delta NL accumulate much higher levels of C99 than cells expressing wild-type APP, we conclude that the rate-limiting step in A beta production could be the further processing of C99 by gamma-secretase in these cells. These results show that the Swedish Delta NL mutation causes nonneuronal cells to process APP via pathways more in common with the metabolism of wild-type APP in neurons.