Subcellular compartment and molecular subdomain of β-amyloid precursor protein relevant to the Aβ42-promoting effects of Alzheimer mutant presenilin 2
Subcellular compartment and molecular subdomain of β-amyloid precursor protein relevant to the Aβ42-promoting effects of Alzheimer mutant presenilin 2
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DOI：
10.1074/jbc.m007989200
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发表时间：
2001-06-15
影响因子：
4.8
通讯作者：
Iwatsubo, T
中科院分区：
文献类型：
--
作者：
Iwata, H;Tomita, T;Iwatsubo, T
终止于 42 位的淀粉样β肽（Aβ42）的产生增加是由与家族性阿尔茨海默病相关的早老素（PS）突变形式引起的致病表型之一。为了确定家族性阿尔茨海默氏病突变体 PS2 (mt PS2) 影响 β APP 的 γ 裂解以增加 A β 42 的亚细胞区室，我们将标记有分选信号的 β APP (C100) 的 C 端 99 个氨基酸片段与内质网 (C100/ER) 或反式高尔基体网络 (C100/TGN) 一起共表达N2a 细胞中的 mt PS2。与 mt PS2 共转染的 C100/TGN 增加了细胞内和分泌的 A beta 42 的水平或比率，其水平与没有信号的 C100 (C100/WT) 相似，而 C100/ER 产生的 A beta 水平可忽略不计，这不受 mt PS2 共转染的影响。共表达的 C100 与 mt PS2 一起在 C 端胞质结构域进行不同的截短，所有类型的 C 端截短的 C100 变体（包括缺乏整个胞质结构域的变体）产生的 A β 分泌形式的水平与 C100/WT 相当，并且 mt PS2 的共转染增加了 A β 42 的分泌。这些结果表明，（i）包括 TGN 在内的晚期细胞内区室是Aβ42 产生并被 mt PS2 上调的主要位点，并且 (ii) 缺乏整个细胞质结构域的 C100 前半部分足以导致 mt PS2 引起的 Aβ42 过量产生。
Increased production of amyloid beta peptides ending at position 42 (A beta 42) is one of the pathogenic phenotypes caused by mutant forms of presenilins (PS) linked to familial Alzheimer's disease. To identify the subcellular compartment(s) in which familial Alzheimer's disease mutant PS2 (mt PS2) affects the gamma -cleavage of beta APP to increase A beta 42, we co-expressed the C-terminal 99-amino acid fragment of beta APP (C100) tagged with sorting signals to the endoplasmic reticulum (C100/ER) or to the trans-Golgi network (C100/TGN) together with mt PS2 in N2a cells. C100/TGN co-transfected with mt PS2 increased levels or ratios of intracellular as well as secreted A beta 42 at similar levels to those with C100 without signals (C100/WT), whereas C100/ER yielded a negligible level of A beta, which was not affected by co-transfection of mt PS2, To identify the molecular subdomain of beta APP required for the effects of mt PS2, we next co-expressed C100 variously truncated at the C-terminal cytoplasmic domain together with mt PS2, All types of C-terminally truncated C100 variants including that lacking the entire cytoplasmic domain yielded the secreted form of A beta at levels comparable with those from C100/WT, and cotransfection of mt PS2 increased the secretion of A beta 42, These results suggest that (i) late intracellular compartments including TGN are the major sites in which A beta 42 is produced and up-regulated by mt PS2 and that (ii) the anterior half of C100 lacking the entire cytoplasmic domain is sufficient for the overproduction of A beta 42 caused by mt PS2.