Amyloid Precursor Protein Revisited NEURON-SPECIFIC EXPRESSION AND HIGHLY STABLE NATURE OF SOLUBLE DERIVATIVES
Amyloid Precursor Protein Revisited NEURON-SPECIFIC EXPRESSION AND HIGHLY STABLE NATURE OF SOLUBLE DERIVATIVES
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DOI：
10.1074/jbc.m111.315051
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发表时间：
2012-01-20
影响因子：
4.8
通讯作者：
Zheng, Hui
中科院分区：
文献类型：
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作者：
Guo, Qinxi;Li, Hongmei;Zheng, Hui
APP的加工和淀粉样β蛋白的产生在阿尔茨海默病的发病机制中起着核心作用。APP一直被认为是一种普遍表达的蛋白质。除了淀粉样β蛋白外，依赖于α或β分泌酶的APP的切割也会产生可溶的分泌型APP(分别是APPSα或APPSβ)。有趣的是，APPSβ被证明受到进一步的切割，以创建一个N-APP片段，该片段与DR6死亡受体结合，并在营养因子停用的条件下介导轴突修剪和退化。通过进行APP免疫细胞化学染色，我们发现，出人意料的是，在APP阴性的样本中，许多抗体产生了非特异性染色。对一系列抗体的筛选使我们能够鉴定出对APP具有高度特异性的兔单抗Y188，并促使我们分别在野生型和APPSβ敲入小鼠中重新检测内源性APP和APPSβ的表达、定位和稳定性。与早期的研究不同，我们发现APP在神经元中特异表达，在基础或神经炎性条件下无法在主要类型的胶质细胞中检测到它的表达。APPα和APPSβ在中枢神经系统(CNS)中高度稳定，在营养因子支持或不支持的情况下都不会进行进一步的切割。我们的结果阐明了与APP基本特性有关的几个关键问题，并为APP的病理生理学提供了关键的细胞学见解。
APP processing and amyloid-beta production play a central role in Alzheimer disease pathogenesis. APP has been considered a ubiquitously expressed protein. In addition to amyloid-beta, alpha- or beta-secretase-dependent cleavage of APP also generates soluble secreted APP (APPs alpha or APPs beta, respectively). Interestingly, APPs beta has been shown to be subject to further cleavage to create an N-APP fragment that binds to the DR6 death receptor and mediates axon pruning and degeneration under trophic factor withdrawal conditions. By performing APP immunocytochemical staining, we found that, unexpectedly, many antibodies yielded nonspecific staining in APP-null samples. Screening of a series of antibodies allowed us to identify a rabbit monoclonal antibody Y188 that is highly specific for APP and prompted us to re-examine the expression, localization, and stability of endogenous APP and APPs beta in wild-type and in APPs beta knock-in mice, respectively. In contrast to earlier studies, we found that APP is specifically expressed in neurons and that its expression cannot be detected in major types of glial cells under basal or neuroinflammatory conditions. Both APPs alpha and APPs beta are highly stable in the central nervous system (CNS) and do not undergo further cleavage with or without trophic factor support. Our results clarify several key questions with regard to the fundamental properties of APP and offer critical cellular insights into the pathophysiology of APP.