Identification of an amino-terminal fragment of apolipoprotein E4 that localizes to neurofibrillary tangles of the Alzheimer's disease brain
Identification of an amino-terminal fragment of apolipoprotein E4 that localizes to neurofibrillary tangles of the Alzheimer's disease brain
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DOI：
10.1016/j.brainres.2012.08.003
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发表时间：
2012-09-26
期刊：
影响因子：
2.9
通讯作者：
Habig, Jeffrey W.
中科院分区：
文献类型：
--
作者：
Rohn, Troy T.;Catlin, Lindsey W.;Habig, Jeffrey W.
虽然载脂蛋白E4 （apoE4）等位基因在晚发性阿尔茨海默病（AD）中的风险因素是众所周知的，但apoE4参与AD发病的机制尚不清楚。相对于其他多态形式，ApoE4亚型的优先切割似乎是显著的，因为产生的片段与AD的特征有关。为了研究apoE4蛋白水解在AD中的可能作用，我们设计了一种针对D172位点的定向抗体，该抗体将产生先前在AD脑提取物中发现的预测氨基末端片段。利用这种新型抗体（称为apoE4的氨基末端裂解片段（nApoE4CF） Ab）进行Western blot分析，在几种从大肠杆菌中纯化的商业形式的人重组apoE4中一致地鉴定出预测的氨基末端片段（类似于18 kDa）。质谱分析证实该18 kDa片段为apoE4的氨基末端片段。免疫组织化学实验表明，nape4cf Ab特异性标记了AD额叶皮层中与成熟缠结标记物PHF-1共定位的神经原纤维缠结（nft）。综上所述，这些结果表明apoE4发生了一种新的裂解事件，产生了一个位于AD大脑nft内的氨基末端片段。(C) 2012 Elsevier B.V.版权所有
Although the risk factor for harboring the apolipoprotein E4 (apoE4) allele in late-onset Alzheimer's disease (AD) is well known, the mechanism by which apoE4 contributes to AD pathogenesis has yet to be clarified. Preferential cleavage of the ApoE4 isoform relative to other polymorphic forms appears to be significant, as the resulting fragments are associated with hallmarks of AD. To examine the possible role of apoE4 proteolysis in AD, we designed a site-directed antibody directed at position D172, which would yield a predicted amino-terminal fragment previously identified in AD brain extracts. Western blot analysis utilizing this novel antibody, termed the amino-terminal apoE4 cleavage fragment (nApoE4CF) Ab, consistently identified the predicted amino-terminal fragment (similar to 18 kDa) in several commercially available forms of human recombinant apoE4 purified from E. coli. Mass spectrometry confirmed the identity of this 18 kDa fragment as being an amino-terminal fragment of apoE4. Immunohistochemical experiments indicated the nApoE4CF Ab specifically labeled neurofibrillary tangles (NFTs) in AD frontal cortex sections that colocalized with the mature tangle marker PHF-1. Taken together, these results suggest a novel cleavage event of apoE4, generating an amino-terminal fragment that localizes within NFTs of the AD brain. (C) 2012 Elsevier B.V. All rights reserved.