Bertrand E, Brouillet E, Caillé I, Bouillot C, Cole G M, Prochiantz A, Allinquant B
Centre National de la Recherche de Scientifique UMR 8542, Ecole normale supérieure, Paris, France.
Mol Cell Neurosci. 2001 Nov;18(5):503-11. doi: 10.1006/mcne.2001.1030.
The amyloid precursor protein presents several cleavage sites leading to the release of its entire C-terminal domain into the cytoplasm. During apoptosis, this C-terminal domain can be cleaved at amino acid 664 by caspases 3, 6, and 8 and can thus generate two peptides N- and C-terminal to amino acid 664 (C31). Recently, it was shown that the C31 induces apoptosis after transfection into N2A and 293 T cell lines. We have analyzed here, by internalization into neurons, the physiological consequences of the entire C-terminal domain (APP-Cter) and of its membrane proximal sequence corresponding to the N-terminal peptide unmasked after caspase cleavage. We find that whereas micromolar concentrations of APP-Cter are harmless, the peptide extending from the membrane (amino acid 649) to the caspase cleavage site (amino acid 664) in the same range of concentrations induces DNA fragmentation, cleavage of actin at a caspase-sensitive site, and activates caspase 3. A mutated version of this sequence (tyrosine 653 replaced by an aspartate) abolishes the effect in vitro and in vivo. Taken together, this report suggests the existence of a new mechanism contributing to Alzheimer's Disease-associated cell death.
淀粉样前体蛋白存在多个切割位点，可导致其整个C末端结构域释放到细胞质中。在细胞凋亡过程中，该C末端结构域可在氨基酸664处被半胱天冬酶3、6和8切割，从而产生氨基酸664（C31）N端和C端的两种肽段。最近研究表明，C31转染到N2A和293 T细胞系后可诱导细胞凋亡。在此，我们通过神经元内化分析了整个C末端结构域（APP-Cter）及其膜近端序列（对应于半胱天冬酶切割后暴露的N端肽段）的生理后果。我们发现，微摩尔浓度的APP-Cter无害，但在相同浓度范围内，从膜（氨基酸649）延伸至半胱天冬酶切割位点（氨基酸664）的肽段可诱导DNA片段化、在半胱天冬酶敏感位点切割肌动蛋白并激活半胱天冬酶3。该序列的突变版本（酪氨酸653被天冬氨酸取代）在体外和体内均消除了这种效应。综上所述，本报告提示存在一种导致阿尔茨海默病相关细胞死亡的新机制。
