APPε, the ε-secretase-derived N-terminal product of the β-amyloid precursor protein, behaves as a type I protein and undergoes α-, β-, and γ-secretase cleavages
APPε, the ε-secretase-derived N-terminal product of the β-amyloid precursor protein, behaves as a type I protein and undergoes α-, β-, and γ-secretase cleavages
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DOI：
10.1111/j.1471-4159.2006.03748.x
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发表时间：
2006-05-01
影响因子：
4.7
通讯作者：
Checler, F
中科院分区：
文献类型：
--
作者：
Lefranc-Jullien, S;Sunyach, C;Checler, F
β-淀粉样肽在受散发性或家族性阿尔茨海默病影响的患者的脑中积累。它来源于β-淀粉样前体蛋白（β APP）通过β-和γ-分泌酶活性的蛋白水解攻击。据报道，在γ-位点的C-末端的几个残基处发生了另外的ATP裂解，导致形成称为APP胞内结构域C50的胞内片段。这种Notch切割受到特别关注，因为它类似于产生Notch胞内结构域的S3 Notch切割。事实上，APP胞内结构域，像它的Notch对应物，似乎介导重要的生理功能。β APP上的γ和γ裂解似乎是时空相关的，但通过诱变方法是不同的和可辨别的。由于这些裂解可以被视为有害的（γ-位点）或有益的（ε-位点），因此似乎最感兴趣的是建立旨在分别研究这些活性的模型，特别是设计特异性和生物可利用的抑制剂。另一方面，重要的是尊重底物的拓扑结构，以检查生理相关的裂解。在这里，我们描述了获得过表达APP β，ε分泌酶衍生的β APP的N-末端片段的细胞。有趣的是，这个N-末端片段的β APP的生物化学和免疫组化方法显示，作为一个真正的膜结合蛋白的行为。APP β经历组成型和蛋白激酶C调节的α-分泌酶裂解。此外，APP β被β-分泌酶β-位点APP裂解酶靶向，随后被γ-分泌酶裂解。所产生的β-淀粉样肽的产生被各种γ-分泌酶抑制剂完全阻止。总之，我们的研究表明，APP β是一个相关的β APP衍生物，研究γ-分泌酶的活动，并设计特定的抑制剂，而不会面临任何速率限制效应的ε-分泌酶衍生的切割。
beta-Amyloid peptide accumulates in the brain of patients affected by sporadic or familial forms of Alzheimer's disease. It derives from the proteolytic attacks of the beta-amyloid precursor protein (beta APP) by beta- and gamma-secretase activities. An additional epsilon cleavage taking place a few residues C-terminal to the gamma-site has been reported, leading to the formation of an intracellular fragment referred to as APP intracellular domain C50. This epsilon cleavage received particular attention because it resembles the S3 Notch cleavage generating Notch intracellular domain. Indeed, APP intracellular domain, like its Notch counterpart, appears to mediate important physiological functions. gamma and epsilon cleavages on beta APP appear spatio-temporally linked but pharmacologically distinct and discriminable by mutagenesis approaches. As these cleavages could be seen as either deleterious (gamma-site) or beneficial (epsilon-site), it appears of most interest to set up models aimed at studying these activities separately, particularly to design specific and bioavailable inhibitors. On the other hand, it is important to respect the topology of the substrates in order to examine physiologically relevant cleavages. Here we describe the obtention of cells overexpressing APP epsilon, the epsilon-secretase-derived N-terminal fragment of beta APP. Interestingly, this N-terminal fragment of beta APP was shown by biochemical and immunohistochemical approaches to behave as a genuine membrane-bound protein. APP epsilon undergoes constitutive and protein kinase C-regulated alpha-secretase cleavages. Furthermore, APP epsilon is targeted by the beta-secretase beta-site APP-cleaving enzyme and is subsequently cleaved by gamma-secretase. The resulting beta-amyloid peptide production is fully prevented by various gamma-secretase inhibitors. Altogether, our study shows that APP epsilon is a relevant beta APP derivative to study gamma-secretase activities and to design specific inhibitors without facing any rate-limiting effect of epsilon-secretase-derived cleavage.