Endoplasmic reticulum and trans-Golgi network generate distinct populations of Alzheimer β-amyloid peptides
Endoplasmic reticulum and trans-Golgi network generate distinct populations of Alzheimer β-amyloid peptides
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DOI：
10.1073/pnas.96.2.742
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发表时间：
1999-01-19
影响因子：
11.1
通讯作者：
Xu, HX
中科院分区：
文献类型：
--
作者：
Greenfield, JP;Tsai, J;Xu, HX
40-和42-aa β-淀粉样肽（A β（40）/A β（42））在选择性脆弱的脑区域中的过度产生和积累是阿尔茨海默病的主要神经病理学特征。β-淀粉样前体蛋白（β APP）通过蛋白水解裂解而衍生，通常分泌。然而，最近的证据表明，显着低水平的A β也可能保留在细胞内，在这里，我们已经调查了亚细胞区室，其中不同的淀粉样物质的产生和区室，他们的分泌，使用了三种实验方法：（i）免疫荧光进行完整的皮质神经元;（ii）用稳定表达野生型β APP（695）（N2 a（695））的小鼠神经母细胞瘤细胞进行蔗糖梯度分级分离;和（iii）A β生成和从N2 a695细胞运输的无细胞重建。这些研究表明：（一）A β（40）（A β（1-40）加A β（x-40），其中x是NH 2末端截短）仅在反式高尔基体网络（TGN）内产生并包装到后TGN分泌囊泡中;（ii）A β（x-42）以不溶性状态产生并保留在内质网内;（iii）A β（42）（AP（1-42）加A β（x-42））在TGN中产生并包装到分泌囊泡中;和（iv）在TGN中形成的淀粉样肽由两个库组成（可用洗涤剂萃取的可溶性群体和洗涤剂不溶性形式），确定产生和分泌不同形式A β的细胞器有助于确定负责其形成的蛋白水解酶。
The excessive generation and accumulation of 40- and 42-aa beta-amyloid peptides (A beta(40)/A beta(42)) in selectively vulnerable brain regions is a major neuropathological feature of Alzheimer's disease. A beta, derived by proteolytic cleavage from the beta-amyloid precursor protein (beta APP), is normally secreted. However, recent evidence suggests that significant le levels of A beta also may remain inside cells, Here, we have investigated the subcellular compartments within which distinct amyloid species are generated and the compartments from which they are secreted, Three experimental approaches were used: (i) immunofluorescence performed in intact cortical neurons; (ii) sucrose gradient fractionation performed with mouse neuroblastoma cells stably expressing wild-type beta APP(695) (N2a(695)); and (iii) cell-free reconstitution of A beta generation and trafficking from N2a695 cells. These studies demonstrate that: (i) A beta(40) (A beta(1-40) plus A beta(x-40), where x is an NH2-terminal truncation) is generated exclusively within the trans-Golgi Network (TGN) and packaged into post-TGN secretory vesicles; (ii) A beta(x-42) is made and retained within the endoplasmic reticulum in an insoluble state; (iii) A beta(42) (AP(1-42) plus A beta(x-42)) is made in the TGN and packaged into secretory vesicles; and (iv) the amyloid peptides formed in the TGN consist of two pools (a soluble population extractable with detergents and a detergent-insoluble form), The identification of the organelles in which distinct forms of A beta are generated and from which they are secreted should facilitate the identification of the proteolytic enzymes responsible for their formation.